US20060213070A1 - Method of sensing tilt, tilt sensor, and method of manufacturing same - Google Patents
Method of sensing tilt, tilt sensor, and method of manufacturing same Download PDFInfo
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- US20060213070A1 US20060213070A1 US11/089,187 US8918705A US2006213070A1 US 20060213070 A1 US20060213070 A1 US 20060213070A1 US 8918705 A US8918705 A US 8918705A US 2006213070 A1 US2006213070 A1 US 2006213070A1
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- tilt sensor
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- tilt
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C9/00—Measuring inclination, e.g. by clinometers, by levels
- G01C9/02—Details
- G01C9/06—Electric or photoelectric indication or reading means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C9/00—Measuring inclination, e.g. by clinometers, by levels
- G01C9/18—Measuring inclination, e.g. by clinometers, by levels by using liquids
- G01C9/20—Measuring inclination, e.g. by clinometers, by levels by using liquids the indication being based on the inclination of the surface of a liquid relative to its container
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C9/00—Measuring inclination, e.g. by clinometers, by levels
- G01C9/02—Details
- G01C9/06—Electric or photoelectric indication or reading means
- G01C2009/068—Electric or photoelectric indication or reading means resistive
Definitions
- the present invention relates generally to tilt sensors. More particularly, the present invention relates to a low-cost, high-volume electrolytic tilt sensor.
- Electrolytic tilt sensors are devices that provide output signals proportional to the angle or direction of tilt in conjunction with a corresponding electrical circuit. Tilt sensors were originally used in weapons delivery and aircraft navigation, but are now used in a wide variety of applications, such as drilling, laser guidance, automotive wheel alignment, geophysical monitoring, virtual reality, and robotic systems.
- Conventional electrolytic tilt sensors also typically incorporate precious metal electrodes, which are sealed and attached by hand and account for a majority of the manufacturing cost of the completed sensor.
- the cost of manufacturing tilt sensors is substantially proportional to the number of electrodes required for each sensor.
- the present invention which addresses the needs of the prior art, relates to a method of sensing tilt, which includes applying an electrical signal to at least one electrode of a first set of spaced-apart electrodes and measuring a first electrical parameter using at least one electrode of a second set of spaced-apart electrodes.
- the first and second sets of electrodes are disposed in a conductive medium and the conductive medium is disposed in an envelope.
- the first electrical parameter is responsive to the applied electrical signal and represents an angle of tilt relative to a first axis, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- the electrical signal can be applied in the form of a voltage or a current and can be applied as a continuous or time-varying signal, such as but not limited to an alternating current (ac) or direct current (dc) signal.
- the electrical roles of the first and second sets of electrodes may be reversed to include applying an electrical signal to at least one electrode of the second set of electrodes, and measuring a second electrical parameter using at least one electrode of the first set of electrodes.
- the second electrical parameter is responsive to the applied electrical signal and represents an angle of tilt relative to a second axis.
- the first set of electrodes and the second set of electrodes may be positioned such that the first axis is substantially non-parallel with the second axis, and the spacing between the first set of electrodes is equal to the spacing separating the second set of electrodes.
- the first electrical parameter may include at least one of voltage, current, resistance, capacitance, impedance, and inductance, and the first and second sets of electrodes each preferably include two electrodes.
- the present invention further relates to a method of sensing tilt relative to a plurality of axes, which may include measuring the first electrical parameter from a first electrode, measuring the first electrical parameter from a second electrode, and combining the first electrical parameter measured from the first electrode and the second electrode.
- the combined first electrical parameter represents the angle of tilt relative to the first axis.
- the present invention still further relates to a tilt sensor, which includes an envelope, a conductive medium disposed in the envelope in an amount adapted to provide a free liquid surface, and at least four electrodes disposed in the envelope such that a portion of each electrode is in contact with the conductive medium.
- the electrodes are electrically insulated from each other to provide at least a first set of spaced-apart electrodes and at least a second set of spaced-apart electrodes.
- At least one electrode of at least one of the first set of electrodes and the second set of electrodes is adapted to be selectively connected to an electrical source such that an electrical signal is applied thereto. At least one electrode of at least one of the first set of electrodes and the second set of electrodes is adapted to be used to provide an electrical parameter in response to the applied electrical signal, wherein the electrical parameter is representative of an angle of tilt relative to at least one axis. No more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- the first set of electrodes defines a first axis
- the second set of electrodes defines a second axis
- the first axis is substantially non-parallel with the second axis.
- the electrodes in each set of electrodes are disposed on substantially opposing sides of a non-conductive projection or envelope, and the tilt sensor preferably includes four electrodes.
- the present invention yet further relates to a tilt sensing system, which includes the tilt sensor, an electrical source adapted to be connected to at least one electrode of at least one of the first set of electrodes and the second set of electrodes such that an electrical signal is applied thereto.
- the system may include one or more mixers adapted to combine at least one of the first electrical parameter and the second electrical parameter.
- the mixer is adapted to provide a tilt parameter representing an angle of tilt relative to at least one axis.
- the electrical source may include a first signal generator and a second signal generator adapted to be connected to electrodes disposed on opposing sides of the non-conductive projection.
- the system may include amplifiers and three-state drivers.
- the present invention still further relates to a method of making a tilt sensor, which includes providing at least four electrodes, forming an envelope adapted to receive at least a portion of the electrodes, placing a conductive medium into the envelope, and sealing the conductive medium in the envelope to be in contact with at least a portion of each electrode.
- the electrodes include at least two sets of spaced-apart electrodes, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- the electrodes may be formed on an electrode stud or an inner surface of the envelope.
- the electrode stud may include a plurality of spaced-apart longitudinal slots, in which the electrodes are disposed.
- the envelope may be adapted to receive at least a portion of a header disk, and the method may include forming the header disk to include an aperture adapted to receive the electrode stud, inserting the electrode stud in the aperture of the header disk, and inserting the header disk in the aperture of the envelope.
- the method may also include forming a seal, which can be a poured or preformed seal made from epoxy or other known sealant material, around the electrode stud in the aperture of the header disk, and applying the seal around the electrode stud in the aperture of the header disk. Sealing the conductive medium in the envelope may include curing the seal.
- the method may also include forming a molded header including the electrode stud and the header disk integral therewith.
- the molded header may include spaced-apart slots extending through apertures in the header disk, or spaced-apart slots substantially aligned with spaced-apart slots disposed on an exterior surface of the header disk.
- the envelope, electrode stud, header disk, seal, and molded header may include at least one of polyphenyleneoxide (PPO®) resin, polypropylene, Vectra®, Peak®, Ultem®, or the like and epoxy.
- PPO® polyphenyleneoxide
- At least two of the envelope, electrode stud, header disk, seal, and molded header may have substantially the same temperature coefficient of expansion.
- the envelope may include a raised boss with an aperture therethrough, and the method may include applying the conductive medium through the aperture in the raised boss, and sealing the aperture in the raised boss.
- the present invention yet further relates to a tilt sensor, which includes at least four electrodes, an envelope adapted to receive at least a portion of the electrodes, and a conductive medium sealed in the envelope.
- the conductive medium is in contact with at least a portion of each electrode.
- the electrodes include at least two sets of spaced-apart electrodes, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- the tilt sensor may include means for connecting the tilt sensor to a circuit board, in which the connecting means includes cantilevered contact arms adapted to connect the electrodes to conductive portions of the circuit board.
- the contact arms may initially be connected to each other and adapted for separation following application to the circuit board.
- the present invention provides electrolytic tilt sensors that are small, lightweight, rugged, simple, inexpensive to manufacture, applicable by various automated and non-automated assembly processes, and require fewer electrodes than conventional tilt sensors.
- the subject tilt sensors are also readily adaptable to mass production techniques within acceptable tolerances for use in a variety of different applications, including, but not limited to applications requiring the measurement of tilt relative to any reference acceleration, such as gravity.
- FIG. 1 is a simplified schematic diagram of a five-pin tilt sensor.
- FIG. 2 is a simplified top view of a four-pin tilt sensor formed in accordance with the present invention.
- FIG. 3 is a simplified schematic diagram of a first embodiment of a signal conditioner circuit that incorporates the tilt sensor shown in FIG. 2 .
- FIG. 3 a is a simplified schematic diagram of a second embodiment of the signal conditioner circuit that incorporates the tilt sensor shown in FIG. 2 .
- FIG. 4 is a portion of the schematic diagram shown in FIG. 3 that is enabled during measurement of tilt with respect to a first axis.
- FIG. 5 is a portion of the schematic diagram shown in FIG. 3 that is enabled during measurement of tilt with respect to a second axis.
- FIG. 6 is a timing diagram for signals shown in the schematic diagram of FIG. 3 .
- FIG. 7 is a cross-sectional view of a first embodiment of the tilt sensor formed in accordance with the present invention.
- FIG. 8 a is a view of an electrode stud for use in barrel plating.
- FIG. 8 b is a top view of an electrode stud for use in the tilt sensor shown in FIG. 7 .
- FIGS. 8 c and 8 d are views of electrode studs adapted for various methods of selective metallization.
- FIGS. 9 a and 9 b are side cross-sectional and top views, respectively, of a header disk for use in the tilt sensor shown in FIG. 7 .
- FIGS. 10 a and 10 b are side cross-sectional and top views, respectively, of a seal for use in the tilt sensor shown in FIG. 7 .
- FIG. 11 is a side cross-sectional view of an envelope for use in the tilt sensor shown in FIG. 7 .
- FIG. 12 is a side cross-sectional view of a second embodiment of the tilt sensor formed in accordance with the present invention.
- FIGS. 13 a and 13 b are side and top views, respectively, of the header disk for use in the tilt sensor shown in FIG. 12 .
- FIG. 14 is a side cross-sectional view of the second embodiment of the envelope for use in the tilt sensor shown in FIG. 12 .
- FIG. 15 a is an isometric view of a molded header for use in a third embodiment of the tilt sensor formed in accordance with the present invention.
- FIG. 15 b is an isometric view of a second embodiment of the molded header shown in FIG. 15 a.
- FIG. 15 c is an isometric view of a third embodiment of the molded header shown in FIG. 15 a.
- FIG. 16 a is an isometric view of a fourth embodiment of the molded header shown in FIG. 15 a.
- FIG. 16 b is a side cross-sectional view of the third embodiment of the tilt sensor including the molded header shown in FIG. 16 a.
- FIG. 17 a is a top view of the molded header shown in FIG. 16 a.
- FIG. 17 b is a side cross-sectional view of the third embodiment of the tilt sensor including the molded header shown in FIG. 16 a.
- FIGS. 18 a and 18 b are bottom views of first and second embodiments of an electrode stud portion of the molded headers shown in FIGS. 15 a , 15 b , 15 c , and 16 a.
- FIGS. 19 a and 19 b are side cross-sectional and top views, respectively, of a fourth embodiment of the tilt sensor formed in accordance with the present invention.
- FIGS. 20 a and 20 b are side cross-sectional views of a fifth embodiment of the tilt sensor formed in accordance with the present invention.
- FIGS. 21 a and 21 b are side and bottom views, respectively, of a sixth embodiment of the tilt sensor formed in accordance with the present invention.
- FIGS. 22 a and 22 b are top and side cross-sectional views, respectively, of a first embodiment of a connector for the tilt sensor formed in accordance with the present invention.
- FIGS. 23 a and 23 b are top and side cross-sectional views, respectively, of a second embodiment of a connector for the tilt sensor formed in accordance with the present invention.
- FIGS. 24 a and 24 b are top and side cross-sectional views, respectively, of a third embodiment of a connector for the tilt sensor formed in accordance with the present invention.
- FIGS. 25 a and 25 b are top and side cross-sectional views, respectively, of a fourth embodiment of a connector for the tilt sensor formed in accordance with the present invention.
- FIG. 1 shows a simplified schematic diagram of a tilt sensing system, which incorporates a five-pin electrolytic tilt sensor 10 .
- the tilt sensor 10 typically includes a housing 12 made of a non-conductive material, such as glass.
- the housing 12 is partially filled with an electrolytic solution 14 such that there is a free liquid surface therein.
- the housing 12 encloses a plurality of electrodes 16 , 18 , 20 , 22 , 24 , which are partially immersed in the electrolytic solution 14 when the tilt sensor 10 is in an upright, zero tilt, or electrical null position.
- One of the electrodes is a common electrode, and the remaining electrodes 16 , 18 , 20 , 22 are sensing electrodes, which are grouped in one or more pairs that define one or more distinct tilt axes 26 , 28 in conjunction with the center common electrode 24 .
- each of the sensing electrodes 16 , 18 , 20 , 22 becomes more or less immersed in the electrolytic solution 14 as the surface of the electrolytic solution 14 is forced to remain parallel to the horizontal plane.
- the increase or decrease in electrode immersion results in a corresponding change in impedance between any one of the sensing electrodes 16 , 18 , 20 , 22 and the common electrode 24 .
- This impedance change is measured as an output signal 30 from the common electrode 24 and correlated to a tilt angle or direction by an electrical conditioning circuit.
- tilt sensors since the cost of manufacturing tilt sensors is substantially proportional to the number of electrodes required for each sensor, it would be advantageous if a tilt sensor could be developed that could function with fewer electrodes. Accordingly, high-volume applications would greatly benefit from such a tilt sensor.
- the present invention solves each of these problems by providing an easy to manufacture, four pin, dual-axis tilt sensor that was not previously known or available.
- FIG. 2 shows a simplified top view of a dual-axis, four-pin tilt sensor 32 formed in accordance with the present invention.
- the reduction from five electrodes in the conventional sensor shown in FIG. 1 to four electrodes shown in FIG. 2 substantially simplifies the design reducing the complexity of testing and enabling a cost-efficient method of manufacturing the sensor.
- the four-pin design of the present invention is also rugged enough for use in the most demanding applications. It is envisioned that the tilt sensor of the present invention could be used in any capacity in which it is desirable to measure tilt in relation to an acceleration, such as the earth's gravity.
- the novel four-pin dual-axis tilt sensor 32 preferably includes four (4) spaced-apart electrodes 16 , 18 , 20 , 22 .
- the electrodes 16 , 18 , 20 , 22 are preferably disposed in a conductive medium 14 , such as an electrolyte or electrolytic fluid, within an envelope 12 .
- Each of the electrodes 16 , 18 , 20 , 22 is also accessible outside the envelope 12 at, for instance, nodes 34 , 36 , 38 , 40 , respectively, which are preferably conductive extensions of the electrodes within the envelope 12 .
- a first electrode 18 is connected to node 36
- a second electrode 22 is connected to node 40
- a third electrode 16 is connected to node 34
- a fourth electrode 20 is connected to node 38 .
- the second electrode 22 and fourth electrode 20 are preferably disposed across from each other on opposite sides of the envelope 12 and form a line that is substantially parallel with a first axis 42 .
- the first electrode 18 and third electrode 16 are preferably disposed across from each other on opposite sides of the envelope 12 and form a line that is substantially parallel with a second axis 44 .
- the first axis 42 is preferably non-parallel with or perpendicular to the second axis 44 .
- FIG. 3 shows a simplified schematic diagram of a signal conditioner circuit 46 , which incorporates the dual-axis four-pin tilt sensor 32 shown in FIG. 2 .
- the signal conditioner circuit 46 preferably includes a first signal generator 48 and a second signal generator 50 , which provide a first excitation signal and a second excitation signal, respectively.
- the signal generators may take any known form, such as but not limited to a voltage source or a current generator.
- An output of the first signal generator 48 is preferably connected to a three-state driver 52 , the output of which is connected to the first electrode 18 of the tilt sensor 32 .
- the second signal generator 50 is preferably connected to a second driver 54 , the output of which is connected to the second electrode 22 .
- the second signal generator 50 is also preferably connected to a third three-state driver 56 , the output of which is connected to the third electrode 16 of the tilt sensor 32 .
- the first signal generator 38 is preferably connected to a fourth three-state driver 58 , the output of which is connected to the fourth electrode 20 .
- the second and fourth three-state drivers 54 , 58 are selectively enabled by a first enable signal 50 .
- the first and third three-state drivers 52 , 56 are preferably enabled by a second enable signal 62 .
- the first electrode 18 is preferably connected to a first amplifier 64 , the output of which is connected to a first mixer 66 .
- the second electrode 22 is preferably connected to a second amplifier 68 , the output of which is connected to a second mixer 70 .
- the third electrode 16 is preferably connected to a third amplifier 72 , the output of which is connected to the first mixer 66 .
- the fourth electrode 18 is preferably connected to a fourth amplifier 74 , the output of which is connected to the second mixer 70 .
- the amplifiers 64 , 68 , 72 , 74 preferably have a relatively high input impedance in comparison to the sensor output resistance.
- the first signal generator 48 is preferably connected to the fourth electrode 20
- the second signal generator 50 is connected to the second electrode 22
- the outputs of the first electrode 18 and third electrode 16 are connected through the first amplifier 64 and the third amplifier 72 , respectively, to the first mixer 66 .
- the first mixer 66 combines outputs from the first and third electrodes 18 , 16 and provides a first tilt signal 78 , which is then used to determine the amount of tilt with respect to the first axis 44 .
- FIG. 4 shows only those components that are enabled by the first enable signal 60 , that is, the second driver 54 and the fourth driver 58 .
- the first amplifier 64 and third amplifier 72 provide signals to the first mixer 66 , the output of which is used to determine the amount of tilt with respect to the first axis 44 .
- the amount of tilt can be determined with respect to the second axis 42 .
- the first signal generator 48 is connected to the first electrode 18
- the second signal generator 50 is connected to the third electrode 16
- the outputs of the second electrode 22 and fourth electrode 20 are connected through the second amplifier 68 and the fourth amplifier 74 , respectively, to the second mixer 70 .
- the second mixer 70 combines the outputs of the second and fourth electrodes 22 , 20 and provides a second tilt signal 76 , which is then used to determine the amount of tilt with respect to the second axis 42 .
- FIG. 5 shows only those components that are enabled by the second enable signal 62 , that is, the first driver 52 and the third driver 56 .
- the second amplifier 68 and fourth amplifier 74 provide signals to the second mixer 70 , the output of which is used to determine the amount of tilt with respect to the second axis 42 .
- FIG. 6 shows a timing diagram for signals associated with the schematic diagram of FIG. 3 .
- Tilt with respect to the first axis 44 shown in FIG. 3 is measured when the first enable signal is high 60 and the second enable signal 62 is low during a period 61 .
- a first excitation signal 80 which is generated by the first signal generator 48
- a second excitation signal 82 which is generated by the second signal generator 50
- is low which is defined as a period 63 .
- a voltage difference which is preferably a time-varying signal, such as an alternating current (ac) signal to substantially eliminate electrode and electrolyte degradation (but may also be a voltage, current, or substantially constant signal) is imposed across the second electrode 22 and the fourth electrode 20 .
- the first signal generator 48 and the second signal generator 50 are preferably disconnected from the first electrode 18 and third electrode 16 , respectively, by keeping the second enable signal 62 low, which keeps the third driver 56 and first driver 52 in the three-state mode.
- a first amplified output signal 84 which is output from the first amplifier 64
- a third amplified output signal 86 which is output from the third amplifier 72 , are summed in the first mixer 66 .
- the first mixer 66 outputs a first tilt signal 78 , which represents the degree of tilt relative to the first axis 44 .
- the voltage appearing across the first electrode 18 and third electrode 16 is proportional to the tilt of the sensor 32 since there is substantially no influence thereon by the first amplifier 64 and third amplifier 72 , due to their high input impedance in comparison with their output impedance, and the first and third electrodes 18 , 16 being equidistant from the second and fourth electrodes 22 , 20 .
- a second amplified output signal 88 which is output from the second amplifier 68
- a fourth amplified output signal 90 which is output from the fourth amplifier 74 , follow the second excitation signal 82 and the first excitation signal 80 , respectively.
- the result is substantially zero, which correctly represents a null measurement with respect to the second axis 42 during measurement of tilt with respect to the first axis 44 .
- tilt with respect to the second axis 44 shown in FIG. 3 is measured when the first enable signal is low 60 and the second enable signal 62 is high during a period 65 .
- the first excitation signal 80 is high, and the second excitation signal 82 is low, which is defined as period 67 .
- period 67 a voltage difference is imposed across the first electrode 18 and third electrode 16 .
- the first signal generator 48 and second signal generator 50 are preferably disconnected from the second electrode 22 and fourth electrode 20 , respectively, by keeping the first enable signal 60 low, which keeps the second driver 54 and fourth driver 58 in the three-state mode.
- the second amplified output signal 88 which is output from the second amplifier 68
- the fourth amplified output signal 90 which is output from the fourth amplifier 74
- the second mixer 70 outputs the second tilt signal 76 , which represents the degree of tilt relative to the second axis 42 .
- the voltage appearing across the second electrode 22 and fourth electrode 20 is proportional to the tilt of the sensor 32 since there is substantially no influence thereon by the second amplifier 68 and fourth amplifier 74 , due to their high input impedance in comparison with their output impedance, and the second and fourth electrodes 22 , 20 being equidistant from the first and third electrodes 18 , 16 .
- the first amplified output signal 84 which is output from the first amplifier 64
- the third amplified output signal 86 which is output from the third amplifier 72 , follow the first excitation signal 80 and the second excitation signal 82 , respectively.
- the result is substantially zero, which correctly represents a null measurement with respect to the first axis 44 during the measurement of tilt with respect to the second axis 42 .
- tilt sensor 32 formed in accordance with the present invention has been described in terms of measuring a variable voltage caused by variations in resistance between electrodes as representing tilt, it is anticipated that the sensor may respond to variations in voltage, current, capacitance, inductance, impedance, and/or other electrical parameters between electrodes to indicate tilt while remaining within the scope of the present invention.
- FIG. 3 a shows a schematic diagram of a second embodiment of the signal conditioner circuit 47 , which incorporates the tilt sensor 32 shown in FIG. 2 .
- the second embodiment 47 is similar to the first embodiment 46 , except that there is preferably only one signal generator 48 , which is connected to each of the three-state drivers 52 , 54 , 56 , 58 , and the mixers 66 , 70 have been eliminated.
- the first signal generator 48 By activating the first enable signal 60 , the first signal generator 48 is connected to the fourth electrode 20 and the second electrode 22 .
- the amount of current is then obtained from the first amplified output signal 84 and the third amplified output signal 86 to determine tilt with respect to the first axis 44 .
- the tilt is such that it causes more electrolytic fluid to be in contact with the first electrode 18 than the third electrode 16 , then the current reading from the first amplified output signal 84 will be correspondingly greater than the current reading from the third amplified output signal 86 , the difference between which is calibrated to provide the angle of tilt relative to the first axis 44 .
- FIG. 7 shows a cross-section of a first embodiment of a tilt sensor 92 formed in accordance with the present invention, which includes an electrode stud 94 , header disk 96 , seal 98 , envelope 100 , and conductive medium, such as an electrolyte or electrolytic solution 102 .
- An ultrasonic seal 103 preferably seals the header disk 96 to the envelope 100 .
- the seal 98 is preferably shaped to fit a counter sunk hole in the header disk 96 to ensure a longer contact with the electrode stud 94 , but may also be shaped to fill a counter bored hole in the header disk 96 , as shown by dotted lines 101 .
- FIG. 8 a shows a side view of the electrode stud 94 for use in barrel plating
- FIG. 8 b shows a bottom view of the electrode stud 94 shown in FIG. 7
- the electrode stud 94 is preferably manufactured or molded from conductive and non-conductive materials, such as polyphenyleneoxide (PPO®) resin, by a two-shot molding process.
- the first shot preferably forms a body 104 of the electrode stud 94 , which includes four (4) spaced-apart slots 106 that preferably run the length of the electrode stud 94 .
- the slots 106 preferably form a mold for the second shot of the process, which includes filling the slots 106 with a conductive material, such as a conductive PPO® resin.
- the second shot preferably forms four (4) separate conductive traces 108 along the length of the electrode stud 94 .
- FIG. 8 c shows the electrode stud 94 with an attached break-off stem 91 .
- the break-off stem 91 is preferably used to position the electrode stud 94 during metallization of the conductive traces 108 by, for example, masking the non-conductive material with a photoresistive material and applying conductive material by vapor deposition or sputtering.
- FIG. 8 d shows a rectangular electrode stud 95 with an attached break-off stem 93 , which may also have a square or rectangular configuration.
- the break-off stem 93 is preferably used to position the electrode stud 94 during metallization of the conductive traces 108 by, for instance electroplating the conductive material.
- the conductive traces may be formed by applying a conductive paint, coating, or other similarly conductive material to the electrode stud, or conductive tape may be applied to form the electrodes.
- a conductive paint, coating, or other similarly conductive material to the electrode stud, or conductive tape may be applied to form the electrodes.
- the described methods of forming the electrodes are not intended to limit the scope of the invention and other methods know to those of ordinary skill in the art are contemplated herein.
- FIGS. 9 a and 9 b show a side cross-sectional view and a top view, respectively, of the header disk 96 , which is preferably shaped as a round disc with a square hole 110 at its center that may be countersunk or counter bored.
- the hole 110 is preferably sized to accept insertion of the electrode stud 94 therethrough.
- the hole 110 is also preferably countersunk or counter bored, as shown in region 112 to accept insertion of the properly dimensioned seal 98 , as shown in FIG. 7 .
- An energy director 105 which is preferably a raised portion of an upper surface of the header disk 96 that mates with the envelope, is shown in FIGS. 9 a , 9 b , 15 a , 15 b , 16 b , 17 b , and 19 a .
- the energy director 105 is melted during the ultrasonic welding process to form a seal between the header disk and envelope.
- dimension 111 is about 0.100
- dimension 113 is about 0.010
- dimension 115 is about 0.050
- dimension 117 is about 0.200
- dimension 119 is about 0.321
- dimension 121 is about 0.110.
- dimension 123 is about 0.203
- dimension 125 is about 0.040.
- dimension 127 is about 0.300
- dimension 129 is about 0.250
- dimension 131 is about 0.322
- dimension 133 is about 0.372
- dimension 135 is about 0.155
- dimension 137 is about 0.120
- dimension 139 is about 0.025.
- FIGS. 10 a and 10 b show a side cross-sectional view and a top view, respectively, of the seal 98 .
- the seal 98 preferably includes a hole 114 , which is dimensioned to fit within the countersunk or counter bored region 112 as indicated by dotted lines 111 , of the header disk 96 and around the electrode stud 94 , which is preferably inserted through the header disk 96 .
- the seal 98 is also preferably manufactured from a curable material, such as epoxy, and formulated such that when cured it will exhibit approximately the same temperature coefficient of expansion as the electrode stud 94 and header disk 96 .
- a header assembly which includes the electrode stud 94 , header disk 96 , and seal 98 , is preferably formed by inserting the electrode stud 94 through the hole 110 in the header disk 96 so that the electrode stud 94 extends from both faces of the header disk 96 at a proper distance and is positioned such that the header disk 96 faces upward.
- the seal 98 is then preferably oriented to fit around the electrode stud 94 and into the countersunk region 112 of the header disk 96 .
- the header assembly is then preferably placed into an environment having a suitable temperature to cure the seal 98 given an appropriate period of time. Curing of the seal 98 preferably produces a hermetic seal between the electrode stud 94 and the header disk 96 in order to retain the electrolytic solution 102 within the envelope 100 .
- the assembly of the electrode stud 94 , header disk 96 , and seal are described above as but one example of a method of forming the electrode assembly for the dual-axis, tilt sensor of the present invention. It is contemplated that variations and different manufacturing techniques may be used to form the electrode assembly, which variations fall within the scope of the invention.
- the stud and header disk may be formed as a single component, or other combinations of these components may be combined to form the electrode assembly.
- FIG. 11 shows a side cross-sectional view of the envelope 100 , which is preferably manufactured from a non-conductive material, such as non-conductive PPO® resin.
- the envelope 100 is preferably formed with a cylindrical shape having a round hollow chamber that is closed at one end with a counter bored or tapered hole 116 at the other end.
- the counter bored or tapered hole 116 is preferably sized to tightly accept the outside circumference of the header disk 96 .
- the first embodiment shown in FIGS. 7-11 is preferably manufactured by positioning the envelope 100 so that its open end is facing up and injecting the electrolytic solution 102 into the open space defined by the envelope 100 .
- the header assembly which includes the electrode stud 94 , header disk 96 , and seal 98 , is then preferably properly oriented and forced onto the shoulder of the counter bored hole 116 in the envelope 100 .
- the header disk 96 is then preferably ultrasonically welded around the periphery of the counter bored hole 116 of the envelope 100 . This hermetically seals the electrolyte 102 within the volume defined by the envelope 100 and the header assembly.
- Other methods of sealing the electrode assembly to the envelope or enclosure known to those of ordinary skill in the art, such as adhesives, epoxies, or the like are contemplated by the present invention.
- FIG. 12 A side cross-sectional view of a second embodiment of a tilt sensor 118 formed in accordance with the present invention is shown in FIG. 12 .
- the second embodiment is similar to the first embodiment shown in FIG. 7 , except that the top end of the envelope 120 includes a small hole 122 centrally or eccentrically located therethrough, which preferably runs through the top wall of the envelope 120 and a raised boss 124 in the envelope 120 .
- the second embodiment is also different in that the header disk 96 and electrode stud 94 are preferably inserted into the counter bored hole 116 of the envelope and a seal 127 is positioned around the electrode stud 94 and forms a hermetic seal against an outer surface of the header disk 126 within the counter bored hole 116 .
- FIGS. 13 a and 13 b show a side cross-sectional view and top view, respectively, of the header disk 126 .
- the header disk 126 includes a hole 128 , which is preferably sized to accept the electrode stud 94 therethrough.
- the header disk 126 shown in FIG. 12 may also include a counter bored, as shown by dotted lines 125 , or countersunk region to accept the correspondingly shaped seal 127 as it forms a hermetic seal against an outer surface of the header disk 126 within the counter bored hole 116 of the envelope 120 .
- FIG. 14 shows a side cross-sectional view of the envelope 120 , which also includes the counter bored hole 116 sized to accept the outside diameter of the header disk 126 and seal 127 therein.
- the second embodiment is preferably manufactured by positioning the envelope 120 such that the open counter bored end is facing up so that the electrode stud 94 and header disk 126 may be properly oriented and forced into the counter bored hole 116 of the envelope 120 , as shown in FIG. 12 .
- the header disk 126 may then be ultrasonically welded around the periphery of the counter bored hole 116 .
- the seal 127 may then be applied to the outer surface of the header disk 126 and cured to provide a hermetic seal.
- the electrolyte 102 is then preferably injected into the envelope 120 through the top hole 122 in the center of the raised boss 124 .
- the hole 122 is then preferably hermetically sealed with, for instance, heat to retain the electrolyte 102 within the envelope 120 .
- FIG. 15 a shows an isometric view of a unitary molded header 130 for use in a third embodiment of the tilt sensor formed in accordance with the present invention.
- the tilt sensor is produced by a two-shot process.
- the first shot includes forming the unitary molded header 130 to include an electrode stud portion 132 and a header disk portion 134 from a non-conductive material, such as PPO® resin.
- the stud portion 132 preferably includes spaced-apart slots 136 that run the entire length of the electrode stud portion 132 and tunnel through the header disk portion 134 .
- the spaced-apart slots 136 preferably form a mold for the second shot of the process, which includes an application of conductive material, such as PPO® resin, to fill each of the preferably four (4) slots 136 .
- the second shot preferably forms four (4) spaced-apart conductive traces 138 through the header disk portion 134 .
- the conductive traces 138 may or may not be selectively plated or metallized.
- the remaining components of the third embodiment of the tilt sensor and its assembly may be substantially the same as that described in relation to the first embodiment.
- FIG. 15 b shows an isometric view of a second embodiment of a unitary molded header 131 for use in the third embodiment of the tilt sensor formed in accordance with the present invention.
- the second embodiment of the molded header 131 is similar to that shown in FIG. 15 a , except that rather than the slots 133 tunneling through the header disk portion 135 , the slots 133 are preferably directed and form channels along the outside of the header disk portion 135 as they connect with the slots 133 on opposing sides of the header disk portion 135 .
- FIG. 15 c shows an isometric view of a third embodiment of a unitary molded header 137 for use in the third embodiment of the tilt sensor formed in accordance with the present invention.
- the third embodiment of the molded header 137 is similar to that shown in FIG. 15 a , except that the electrode stud portion 139 and header disk portion 141 are rectangular or square rather than rounded.
- FIG. 16 b shows a side cross-sectional view of a fourth embodiment of the tilt sensor 140 formed in accordance with the present invention.
- FIG. 16 a shows a top isometric view of a molded header 142 for use in the fourth embodiment of the tilt sensor 140 shown in FIG. 16 b .
- the fourth embodiment is similar to the third embodiment, except that the molded header 142 includes an electrode stud portion 144 that extends from only one side of the header disk portion 146 .
- the opposite side of the header disk portion, from which the electrode stud portion 146 does not extend, preferably includes conductive pads 148 , which are manufactured from, for instance, conductive PPO® resin, that are electrically connected to each of the conductive traces 138 on the electrode stud portion 144 .
- the header disk portion 146 preferably also includes orientation studs 150 that extend from the face of the header disk portion 146 , from which the electrode stud portion 144 does not protrude.
- the orientation studs 150 are preferably mounted within corresponding apertures in, for instance, a printed circuit board to maintain the alignment of the tilt sensor with respect thereto.
- FIG. 16 a shows a side cross-sectional view of the molded header 142 mounted within an envelope 152 , in which the electrically conductive pads 148 face upwards.
- FIG. 17 a shows a top view of the molded header 142 including the orientation studs 150 and conductive pads 148 .
- FIG. 17 b shows a side cross-sectional view of the molded header 142 mounted within the envelope 152 .
- FIGS. 18 a and 18 b show bottom end views of alternative embodiments for the electrode stud portion 144 shown in FIG. 16 a.
- FIGS. 19 a and 19 b show a side cross-sectional view and a top view, respectively, of a fifth embodiment of the tilt sensor 154 formed in accordance with the present invention.
- the tilt sensor 154 preferably includes an envelope 156 produced by a two-shot molding process.
- the first shot forms the non-conductive cylindrical envelope 156 having a round hollow chamber that is closed at one end 151 and counter bored at the other end 153 .
- the envelope 156 also preferably includes spaced-apart vertical voids 158 that run the length of the envelope 156 .
- the walls 157 of the envelope 156 are held in place between the voids 158 by their attachment to the closed end 151 of the envelope 156 .
- the voids 158 preferably form a mold for the second-shot, which includes placement of a conductive material, such as PPO® resin, to fill the spaced-apart voids 158 .
- a conductive material such as PPO® resin
- This preferably forms spaced-apart conductive traces 160 along the inside and outside lengths of the envelope 156 .
- the conductive traces may or may not be selectively plated or metallized.
- the electrodes may be formed in the envelope by applying a conductive material thereto in the form of paint, coating, tape, or other suitable method of application known to those of ordinary skill in the art.
- the envelope 156 may also include a protruding orientation stud 162 adapted to be inserted into a corresponding aperture in, for instance, a printed circuit board, to maintain the position of the tilt sensor 154 after mounting.
- the tilt sensor 154 preferably also includes a non-conductive header disk 164 that is sized to fit tightly into the counter bored hole of the envelope 156 .
- the tilt sensor 154 is preferably assembled by positioning the envelope 156 such that its open end 153 is facing upward.
- the electrolyte 86 is then preferably injected into the volume defined by the envelope 156 and the cover disk or header disk 164 is forced into and seated onto the shoulder of the counter bored end 153 of the envelope 156 .
- the header disk 164 is then preferably ultrasonically welded around the periphery of the counter bored shoulder to hermetically seal the electrolyte 86 within the envelope 156 .
- FIG. 20 a shows a side cross-sectional view of a sixth embodiment of the tilt sensor 165 mounted to a printed circuit board 167 .
- the tilt sensor 165 is similar to the fifth embodiment, except that the voids of the fifth embodiment have been replaced with slots 169 on an interior surface of the envelope 156 that preferably extend through only a bottom surface of the envelope 156 .
- the slots 169 are preferably filled with conductive material 171 that protrudes from the bottom surface of the envelope 156 to make electrical contact with a contact arm 173 positioned on the board 167 .
- the tilt sensor 165 also differs from the fourth embodiment in that it includes at least one stud 175 , which is preferably molded with the envelope 156 and protrudes from the bottom surface thereof.
- the stud 175 is preferably positioned at the center of the bottom surface of the envelope 156 , as shown in FIG. 20 b , but may be positioned at any other location thereon, as shown in FIG. 20 a , while remaining within the scope of the present invention.
- Each of the studs 175 includes a reduced portion 177 , which is sized to fit through a hole in the printed circuit board 167 , such that the tilt sensor 165 is held above the board 167 .
- An end of the reduced portion 177 that extends from the printed circuit board 167 is preferably heated to form a knob 179 thereon, thereby retaining the tilt sensor 165 in its intended position on the board 167 .
- the contact arm 173 is preferably jogged or elevated from the upper surface of the printed circuit board 167 by an amount greater than the distance between the protruding conductive material 171 , such that the contact arm 173 is biased against the protruding conductive material 171 to ensure adequate electrical connection therewith.
- FIGS. 21 a and 21 b show side and bottom views, respectively, of a sixth embodiment of the four-pin tilt sensor 155 in accordance with the present invention, which includes a glass envelope 159 , four (4) wire electrodes 156 , and electrolytic fluid 163 .
- the tilt sensor 155 is preferably manufactured by methods well known to those skilled in the art, except that the tilt sensor requires only four (4) electrodes to determine tilt with respect to two axes (as discussed above with respect to the signal conditioning circuits shown in FIGS. 3, 3 a , and 4 - 6 .
- the electrolytic tilt sensors formed in accordance with the present invention preferably include one or more of the following features:
- tilt sensor embodiments described above are intended as examples without limiting the scope of the present invention in any way, which may incorporate any or all of the features of the exemplary embodiments, as well as the following:
- FIG. 22 a shows a top view of a first embodiment of a tilt sensor connector 166 that includes four (4) contact arms 168 , which are adapted to electrically connect the conductive traces 108 on the electrode stud 94 with additional circuitry on, for example, a printed circuit board.
- FIG. 22 b shows a side cross-sectional view of the tilt sensor 118 inserted into the sensor connector 166 and applied to the printed circuit board 170 .
- Each of the contact arms 168 preferably includes a sensor portion 172 , which makes contact with one of the conductive traces 108 on the electrode stud 94 , and a board portion 174 , which makes contact with circuitry on the printed circuit board 170 .
- the sensor portion 172 and board portion 174 are connected by a length of the contact arm 168 that is preferably positioned along a surface of the printed circuit board 170 .
- the board portion 174 is bent such that it can be inserted into an aperture in the printed circuit board 170 for retention therein by, for example, soldering.
- the sensor portion 172 is bent or cantilevered such that it exerts a spring-like tension, as indicated by a dotted phantom 173 of the sensor portion 172 , to maintain electrical conductivity with the conductive trace 108 when the electrode stud 94 is inserted into the sensor connector 166 .
- FIG. 23 a shows a top view of a second embodiment of a tilt sensor connector 176 , which includes four (4) contact arms 178 that are adapted to electrically connect the conductive traces 108 on the electrode stud 94 with additional circuitry on the printed circuit board 170 shown in FIG. 23 b .
- the tilt sensor connector 176 is preferably manufactured and applied to the printed circuit board 170 as a single piece with v-notches 180 , which can thereafter be stamped to electrically isolate the contact arms 178 from each other.
- FIG. 23 b shows a side cross-sectional view of the electrode stud 94 of a tilt sensor mounted in the connector 176 , which has been applied to the printed circuit board 170 .
- Each of the contact arms 168 preferably includes a sensor portion 182 , which makes contact with one of the conductive traces 108 .
- the sensor connector also includes one or more tabs 184 that are, for example, adapted for being push-fit into holes in the printed circuit board 170 to maintain the orientation of the tilt sensor.
- the sensor portion 182 is preferably bent such that it exerts a spring-like tension, as indicated by a dotted phantom 173 of the sensor portion 172 , to maintain electrical conductivity with the conductive trace 108 when the electrode stud 94 is inserted into the sensor connector 176 .
- the v-notches 180 are preferably positioned over depressions in the printed circuit board 170 such that when stamped with a minimal amount of force, the quadrants of the sensor connector 176 are electrically isolated from each other.
- FIG. 24 a shows a top view of a third embodiment of a tilt sensor connector 186 , which includes four (4) contact arms 188 that are adapted to electrically connect the conductive traces 108 on the electrode stud 94 with additional circuitry.
- FIG. 24 b shows a side cross-sectional view of the electrode stud 94 of a tilt sensor mounted in the connector 186 .
- the third embodiment of the sensor connector 186 is similar to the second embodiment of the sensor connector 176 , except that rounded edges in the second embodiment have been replaced by straight edges in the third embodiment.
- FIG. 25 a shows a top view of a fourth embodiment of a tilt sensor connector 190 adapted for use with the sixth embodiment of the tilt sensor 165 shown in FIGS. 20 a and 20 b .
- the tilt sensor connector 190 includes four (4) contact arms 192 that are adapted to electrically connect the conductive material 171 protruding from the bottom surface of the envelope 156 with additional circuitry.
- the tilt sensor connector 190 is preferably manufactured and applied to the printed circuit board 170 as a single piece with v-notches 180 , which can thereafter be stamped to electrically isolate the contact arms 192 from each other.
- FIG. 25 b shows a side cross-sectional view of the tilt sensor 165 mounted in the connector 190 .
- Each of the contact arms 192 preferably includes a sensor portion 194 , which makes contact with the protruding conductive material 171 .
- the sensor connector also includes one or more tabs 196 that are, for example, adapted for being push-fit into holes 198 in the printed circuit board 170 to maintain the orientation of the tilt sensor.
- the sensor portion 194 is preferably bent such that it exerts a spring-like tension, as indicated by a dotted phantom 200 of the sensor portion 194 , to maintain electrical conductivity with the conductive material 171 .
- the v-notches 180 are preferably positioned over depressions in the printed circuit board 170 , such that when stamped with a minimal amount of force, the quadrants of the sensor connector 190 are electrically isolated from each other.
- the sensor connectors 166 , 176 , 186 are adaptable to being reel fed and placed onto a printed circuit board, soldered (hand or wave) in place, and, in the case of sensor connectors 176 , 186 , separated into individual contacts to accept the electrode stud 94 .
- the tilt sensor is preferably fixed in place using, for example, an adhesive or laminate.
- the present invention provides electrolytic tilt sensors that are small, lightweight, rugged, simple, inexpensive to manufacture, applicable by various automated and non-automated mounting processes, and require fewer electrodes than conventional tilt sensors.
- the subject tilt sensors are also readily adaptable to mass production techniques within acceptable tolerances for use in a variety of different applications.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates generally to tilt sensors. More particularly, the present invention relates to a low-cost, high-volume electrolytic tilt sensor.
- 2. Description of the Related Art
- Electrolytic tilt sensors are devices that provide output signals proportional to the angle or direction of tilt in conjunction with a corresponding electrical circuit. Tilt sensors were originally used in weapons delivery and aircraft navigation, but are now used in a wide variety of applications, such as drilling, laser guidance, automotive wheel alignment, geophysical monitoring, virtual reality, and robotic systems.
- Disadvantages commonly associated with conventional electrolytic tilt sensors include difficulties in manufacturing the sensor. Moreover, sensor manufacture requires a significant degree of skill, fixturing, labor-intensive handwork, and art by highly trained operators to achieve the desired parameters. In addition, tolerances of the glass housing during its processing can vary greatly, which results in either a higher reject rate and/or a greater range of mechanical and electrical tolerances in the end product. Further, tilt sensor components are relatively fragile due to their construction and must be handled with extreme caution.
- With respect to glass electrolytic tilt sensors, great care must be afforded to the thermal and mechanical stress related characteristics of the glass during installation and alignment. This significantly limits the range of application of such sensors.
- Conventional electrolytic tilt sensors also typically incorporate precious metal electrodes, which are sealed and attached by hand and account for a majority of the manufacturing cost of the completed sensor. Thus, the cost of manufacturing tilt sensors is substantially proportional to the number of electrodes required for each sensor.
- Therefore, there is a need in the prior art for an electrolytic tilt sensor that is small, lightweight, rugged, simple, inexpensive to manufacture, applicable by various automated mounting processes, and requires fewer electrodes than conventional sensors. The need also exists for a tilt sensor that is readily adaptable to mass production techniques within acceptable tolerances.
- The present invention, which addresses the needs of the prior art, relates to a method of sensing tilt, which includes applying an electrical signal to at least one electrode of a first set of spaced-apart electrodes and measuring a first electrical parameter using at least one electrode of a second set of spaced-apart electrodes. The first and second sets of electrodes are disposed in a conductive medium and the conductive medium is disposed in an envelope. The first electrical parameter is responsive to the applied electrical signal and represents an angle of tilt relative to a first axis, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes. The electrical signal can be applied in the form of a voltage or a current and can be applied as a continuous or time-varying signal, such as but not limited to an alternating current (ac) or direct current (dc) signal.
- The electrical roles of the first and second sets of electrodes may be reversed to include applying an electrical signal to at least one electrode of the second set of electrodes, and measuring a second electrical parameter using at least one electrode of the first set of electrodes. The second electrical parameter is responsive to the applied electrical signal and represents an angle of tilt relative to a second axis.
- The first set of electrodes and the second set of electrodes may be positioned such that the first axis is substantially non-parallel with the second axis, and the spacing between the first set of electrodes is equal to the spacing separating the second set of electrodes. The first electrical parameter may include at least one of voltage, current, resistance, capacitance, impedance, and inductance, and the first and second sets of electrodes each preferably include two electrodes.
- The present invention further relates to a method of sensing tilt relative to a plurality of axes, which may include measuring the first electrical parameter from a first electrode, measuring the first electrical parameter from a second electrode, and combining the first electrical parameter measured from the first electrode and the second electrode. The combined first electrical parameter represents the angle of tilt relative to the first axis.
- The present invention still further relates to a tilt sensor, which includes an envelope, a conductive medium disposed in the envelope in an amount adapted to provide a free liquid surface, and at least four electrodes disposed in the envelope such that a portion of each electrode is in contact with the conductive medium. The electrodes are electrically insulated from each other to provide at least a first set of spaced-apart electrodes and at least a second set of spaced-apart electrodes.
- At least one electrode of at least one of the first set of electrodes and the second set of electrodes is adapted to be selectively connected to an electrical source such that an electrical signal is applied thereto. At least one electrode of at least one of the first set of electrodes and the second set of electrodes is adapted to be used to provide an electrical parameter in response to the applied electrical signal, wherein the electrical parameter is representative of an angle of tilt relative to at least one axis. No more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- The first set of electrodes defines a first axis, the second set of electrodes defines a second axis, and the first axis is substantially non-parallel with the second axis. The electrodes in each set of electrodes are disposed on substantially opposing sides of a non-conductive projection or envelope, and the tilt sensor preferably includes four electrodes.
- The present invention yet further relates to a tilt sensing system, which includes the tilt sensor, an electrical source adapted to be connected to at least one electrode of at least one of the first set of electrodes and the second set of electrodes such that an electrical signal is applied thereto. The system may include one or more mixers adapted to combine at least one of the first electrical parameter and the second electrical parameter. The mixer is adapted to provide a tilt parameter representing an angle of tilt relative to at least one axis.
- The electrical source may include a first signal generator and a second signal generator adapted to be connected to electrodes disposed on opposing sides of the non-conductive projection. The system may include amplifiers and three-state drivers.
- The present invention still further relates to a method of making a tilt sensor, which includes providing at least four electrodes, forming an envelope adapted to receive at least a portion of the electrodes, placing a conductive medium into the envelope, and sealing the conductive medium in the envelope to be in contact with at least a portion of each electrode. The electrodes include at least two sets of spaced-apart electrodes, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- The electrodes may be formed on an electrode stud or an inner surface of the envelope. The electrode stud may include a plurality of spaced-apart longitudinal slots, in which the electrodes are disposed. The envelope may be adapted to receive at least a portion of a header disk, and the method may include forming the header disk to include an aperture adapted to receive the electrode stud, inserting the electrode stud in the aperture of the header disk, and inserting the header disk in the aperture of the envelope.
- The method may also include forming a seal, which can be a poured or preformed seal made from epoxy or other known sealant material, around the electrode stud in the aperture of the header disk, and applying the seal around the electrode stud in the aperture of the header disk. Sealing the conductive medium in the envelope may include curing the seal.
- The method may also include forming a molded header including the electrode stud and the header disk integral therewith. The molded header may include spaced-apart slots extending through apertures in the header disk, or spaced-apart slots substantially aligned with spaced-apart slots disposed on an exterior surface of the header disk. The envelope, electrode stud, header disk, seal, and molded header may include at least one of polyphenyleneoxide (PPO®) resin, polypropylene, Vectra®, Peak®, Ultem®, or the like and epoxy.
- At least two of the envelope, electrode stud, header disk, seal, and molded header may have substantially the same temperature coefficient of expansion. The envelope may include a raised boss with an aperture therethrough, and the method may include applying the conductive medium through the aperture in the raised boss, and sealing the aperture in the raised boss.
- The present invention yet further relates to a tilt sensor, which includes at least four electrodes, an envelope adapted to receive at least a portion of the electrodes, and a conductive medium sealed in the envelope. The conductive medium is in contact with at least a portion of each electrode. The electrodes include at least two sets of spaced-apart electrodes, such that no more than four electrodes provide electrical parameters representative of angles of tilt relative to two non-parallel axes.
- The tilt sensor may include means for connecting the tilt sensor to a circuit board, in which the connecting means includes cantilevered contact arms adapted to connect the electrodes to conductive portions of the circuit board. The contact arms may initially be connected to each other and adapted for separation following application to the circuit board.
- As a result, the present invention provides electrolytic tilt sensors that are small, lightweight, rugged, simple, inexpensive to manufacture, applicable by various automated and non-automated assembly processes, and require fewer electrodes than conventional tilt sensors. The subject tilt sensors are also readily adaptable to mass production techniques within acceptable tolerances for use in a variety of different applications, including, but not limited to applications requiring the measurement of tilt relative to any reference acceleration, such as gravity.
- These and other objects, features, and advantages of this invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
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FIG. 1 is a simplified schematic diagram of a five-pin tilt sensor. -
FIG. 2 is a simplified top view of a four-pin tilt sensor formed in accordance with the present invention. -
FIG. 3 is a simplified schematic diagram of a first embodiment of a signal conditioner circuit that incorporates the tilt sensor shown inFIG. 2 . -
FIG. 3 a is a simplified schematic diagram of a second embodiment of the signal conditioner circuit that incorporates the tilt sensor shown inFIG. 2 . -
FIG. 4 is a portion of the schematic diagram shown inFIG. 3 that is enabled during measurement of tilt with respect to a first axis. -
FIG. 5 is a portion of the schematic diagram shown inFIG. 3 that is enabled during measurement of tilt with respect to a second axis. -
FIG. 6 is a timing diagram for signals shown in the schematic diagram ofFIG. 3 . -
FIG. 7 is a cross-sectional view of a first embodiment of the tilt sensor formed in accordance with the present invention. -
FIG. 8 a is a view of an electrode stud for use in barrel plating. -
FIG. 8 b is a top view of an electrode stud for use in the tilt sensor shown inFIG. 7 . -
FIGS. 8 c and 8 d are views of electrode studs adapted for various methods of selective metallization. -
FIGS. 9 a and 9 b are side cross-sectional and top views, respectively, of a header disk for use in the tilt sensor shown inFIG. 7 . -
FIGS. 10 a and 10 b are side cross-sectional and top views, respectively, of a seal for use in the tilt sensor shown inFIG. 7 . -
FIG. 11 is a side cross-sectional view of an envelope for use in the tilt sensor shown inFIG. 7 . -
FIG. 12 is a side cross-sectional view of a second embodiment of the tilt sensor formed in accordance with the present invention. -
FIGS. 13 a and 13 b are side and top views, respectively, of the header disk for use in the tilt sensor shown inFIG. 12 . -
FIG. 14 is a side cross-sectional view of the second embodiment of the envelope for use in the tilt sensor shown inFIG. 12 . -
FIG. 15 a is an isometric view of a molded header for use in a third embodiment of the tilt sensor formed in accordance with the present invention. -
FIG. 15 b is an isometric view of a second embodiment of the molded header shown inFIG. 15 a. -
FIG. 15 c is an isometric view of a third embodiment of the molded header shown inFIG. 15 a. -
FIG. 16 a is an isometric view of a fourth embodiment of the molded header shown inFIG. 15 a. -
FIG. 16 b is a side cross-sectional view of the third embodiment of the tilt sensor including the molded header shown inFIG. 16 a. -
FIG. 17 a is a top view of the molded header shown inFIG. 16 a. -
FIG. 17 b is a side cross-sectional view of the third embodiment of the tilt sensor including the molded header shown inFIG. 16 a. -
FIGS. 18 a and 18 b are bottom views of first and second embodiments of an electrode stud portion of the molded headers shown inFIGS. 15 a, 15 b, 15 c, and 16 a. -
FIGS. 19 a and 19 b are side cross-sectional and top views, respectively, of a fourth embodiment of the tilt sensor formed in accordance with the present invention. -
FIGS. 20 a and 20 b are side cross-sectional views of a fifth embodiment of the tilt sensor formed in accordance with the present invention. -
FIGS. 21 a and 21 b are side and bottom views, respectively, of a sixth embodiment of the tilt sensor formed in accordance with the present invention. -
FIGS. 22 a and 22 b are top and side cross-sectional views, respectively, of a first embodiment of a connector for the tilt sensor formed in accordance with the present invention. -
FIGS. 23 a and 23 b are top and side cross-sectional views, respectively, of a second embodiment of a connector for the tilt sensor formed in accordance with the present invention. -
FIGS. 24 a and 24 b are top and side cross-sectional views, respectively, of a third embodiment of a connector for the tilt sensor formed in accordance with the present invention. -
FIGS. 25 a and 25 b are top and side cross-sectional views, respectively, of a fourth embodiment of a connector for the tilt sensor formed in accordance with the present invention. -
FIG. 1 shows a simplified schematic diagram of a tilt sensing system, which incorporates a five-pinelectrolytic tilt sensor 10. Thetilt sensor 10 typically includes ahousing 12 made of a non-conductive material, such as glass. Thehousing 12 is partially filled with anelectrolytic solution 14 such that there is a free liquid surface therein. Thehousing 12 encloses a plurality ofelectrodes electrolytic solution 14 when thetilt sensor 10 is in an upright, zero tilt, or electrical null position. One of the electrodes, typically acenter electrode 24, is a common electrode, and the remainingelectrodes common electrode 24. - As the
sensor 10 is tilted with respect to a horizontal plane, each of thesensing electrodes electrolytic solution 14 as the surface of theelectrolytic solution 14 is forced to remain parallel to the horizontal plane. The increase or decrease in electrode immersion results in a corresponding change in impedance between any one of thesensing electrodes common electrode 24. This impedance change is measured as an output signal 30 from thecommon electrode 24 and correlated to a tilt angle or direction by an electrical conditioning circuit. - However, since the cost of manufacturing tilt sensors is substantially proportional to the number of electrodes required for each sensor, it would be advantageous if a tilt sensor could be developed that could function with fewer electrodes. Accordingly, high-volume applications would greatly benefit from such a tilt sensor. The present invention solves each of these problems by providing an easy to manufacture, four pin, dual-axis tilt sensor that was not previously known or available.
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FIG. 2 shows a simplified top view of a dual-axis, four-pin tilt sensor 32 formed in accordance with the present invention. The reduction from five electrodes in the conventional sensor shown inFIG. 1 to four electrodes shown inFIG. 2 substantially simplifies the design reducing the complexity of testing and enabling a cost-efficient method of manufacturing the sensor. The four-pin design of the present invention is also rugged enough for use in the most demanding applications. It is envisioned that the tilt sensor of the present invention could be used in any capacity in which it is desirable to measure tilt in relation to an acceleration, such as the earth's gravity. - The novel four-pin dual-
axis tilt sensor 32 preferably includes four (4) spaced-apartelectrodes electrodes conductive medium 14, such as an electrolyte or electrolytic fluid, within anenvelope 12. Each of theelectrodes envelope 12 at, for instance,nodes envelope 12. - Specifically, a
first electrode 18 is connected tonode 36, asecond electrode 22 is connected tonode 40, athird electrode 16 is connected tonode 34, and afourth electrode 20 is connected tonode 38. Thesecond electrode 22 andfourth electrode 20 are preferably disposed across from each other on opposite sides of theenvelope 12 and form a line that is substantially parallel with afirst axis 42. Likewise, thefirst electrode 18 andthird electrode 16 are preferably disposed across from each other on opposite sides of theenvelope 12 and form a line that is substantially parallel with asecond axis 44. Thefirst axis 42 is preferably non-parallel with or perpendicular to thesecond axis 44. -
FIG. 3 shows a simplified schematic diagram of asignal conditioner circuit 46, which incorporates the dual-axis four-pin tilt sensor 32 shown inFIG. 2 . Thesignal conditioner circuit 46 preferably includes afirst signal generator 48 and asecond signal generator 50, which provide a first excitation signal and a second excitation signal, respectively. The signal generators may take any known form, such as but not limited to a voltage source or a current generator. An output of thefirst signal generator 48 is preferably connected to a three-state driver 52, the output of which is connected to thefirst electrode 18 of thetilt sensor 32. Thesecond signal generator 50 is preferably connected to asecond driver 54, the output of which is connected to thesecond electrode 22. - The
second signal generator 50 is also preferably connected to a third three-state driver 56, the output of which is connected to thethird electrode 16 of thetilt sensor 32. Thefirst signal generator 38 is preferably connected to a fourth three-state driver 58, the output of which is connected to thefourth electrode 20. The second and fourth three-state drivers first enable signal 50. The first and third three-state drivers signal 62. - The
first electrode 18 is preferably connected to afirst amplifier 64, the output of which is connected to afirst mixer 66. Thesecond electrode 22 is preferably connected to asecond amplifier 68, the output of which is connected to asecond mixer 70. Thethird electrode 16 is preferably connected to athird amplifier 72, the output of which is connected to thefirst mixer 66. Thefourth electrode 18 is preferably connected to afourth amplifier 74, the output of which is connected to thesecond mixer 70. Theamplifiers - By activating the first enable
signal 60, thefirst signal generator 48 is preferably connected to thefourth electrode 20, thesecond signal generator 50 is connected to thesecond electrode 22, and the outputs of thefirst electrode 18 andthird electrode 16 are connected through thefirst amplifier 64 and thethird amplifier 72, respectively, to thefirst mixer 66. Thefirst mixer 66 combines outputs from the first andthird electrodes first tilt signal 78, which is then used to determine the amount of tilt with respect to thefirst axis 44. - This situation is simplified in
FIG. 4 , which shows only those components that are enabled by the first enablesignal 60, that is, thesecond driver 54 and thefourth driver 58. In this case, thefirst amplifier 64 andthird amplifier 72 provide signals to thefirst mixer 66, the output of which is used to determine the amount of tilt with respect to thefirst axis 44. - Likewise, referring back to
FIG. 3 , the amount of tilt can be determined with respect to thesecond axis 42. Specifically, by activating the second enablesignal 62, thefirst signal generator 48 is connected to thefirst electrode 18, thesecond signal generator 50 is connected to thethird electrode 16, and the outputs of thesecond electrode 22 andfourth electrode 20 are connected through thesecond amplifier 68 and thefourth amplifier 74, respectively, to thesecond mixer 70. Thesecond mixer 70 combines the outputs of the second andfourth electrodes second tilt signal 76, which is then used to determine the amount of tilt with respect to thesecond axis 42. - This situation is simplified in
FIG. 5 , which shows only those components that are enabled by the second enablesignal 62, that is, thefirst driver 52 and thethird driver 56. In this case, thesecond amplifier 68 andfourth amplifier 74 provide signals to thesecond mixer 70, the output of which is used to determine the amount of tilt with respect to thesecond axis 42. -
FIG. 6 shows a timing diagram for signals associated with the schematic diagram ofFIG. 3 . Tilt with respect to thefirst axis 44 shown inFIG. 3 is measured when the first enable signal is high 60 and the second enablesignal 62 is low during aperiod 61. During a portion ofperiod 61, afirst excitation signal 80, which is generated by thefirst signal generator 48, is high, and asecond excitation signal 82, which is generated by thesecond signal generator 50, is low, which is defined as aperiod 63. Duringperiod 63, a voltage difference, which is preferably a time-varying signal, such as an alternating current (ac) signal to substantially eliminate electrode and electrolyte degradation (but may also be a voltage, current, or substantially constant signal) is imposed across thesecond electrode 22 and thefourth electrode 20. During theperiod 63, thefirst signal generator 48 and thesecond signal generator 50 are preferably disconnected from thefirst electrode 18 andthird electrode 16, respectively, by keeping the second enablesignal 62 low, which keeps thethird driver 56 andfirst driver 52 in the three-state mode. - This essentially places the
second electrode 22 andfourth electrode 20 in a Wheatstone bridge configuration, the output of which is provided on thefirst electrode 18 andthird electrode 16 through thefirst amplifier 64 andthird amplifier 72, respectively. A first amplifiedoutput signal 84, which is output from thefirst amplifier 64, and a third amplifiedoutput signal 86, which is output from thethird amplifier 72, are summed in thefirst mixer 66. Thefirst mixer 66 outputs afirst tilt signal 78, which represents the degree of tilt relative to thefirst axis 44. - During
period 63, the voltage appearing across thefirst electrode 18 andthird electrode 16 is proportional to the tilt of thesensor 32 since there is substantially no influence thereon by thefirst amplifier 64 andthird amplifier 72, due to their high input impedance in comparison with their output impedance, and the first andthird electrodes fourth electrodes period 63, a second amplifiedoutput signal 88, which is output from thesecond amplifier 68, and a fourth amplifiedoutput signal 90, which is output from thefourth amplifier 74, follow thesecond excitation signal 82 and thefirst excitation signal 80, respectively. Thus, when the second amplifiedoutput signal 88 and fourth amplifiedoutput signal 90 are combined in thesecond mixer 70, the result is substantially zero, which correctly represents a null measurement with respect to thesecond axis 42 during measurement of tilt with respect to thefirst axis 44. - Similarly, tilt with respect to the
second axis 44 shown inFIG. 3 is measured when the first enable signal is low 60 and the second enablesignal 62 is high during aperiod 65. During a portion ofperiod 65, thefirst excitation signal 80 is high, and thesecond excitation signal 82 is low, which is defined asperiod 67. Duringperiod 67, a voltage difference is imposed across thefirst electrode 18 andthird electrode 16. Also duringperiod 67, thefirst signal generator 48 andsecond signal generator 50 are preferably disconnected from thesecond electrode 22 andfourth electrode 20, respectively, by keeping the first enablesignal 60 low, which keeps thesecond driver 54 andfourth driver 58 in the three-state mode. - This essentially places the
first electrode 18 andthird electrode 16 in a Wheatstone bridge configuration, the output of which is provided on thesecond electrode 22 andfourth electrode 20 through thesecond amplifier 68 andfourth amplifier 74, respectively. The second amplifiedoutput signal 88, which is output from thesecond amplifier 68, and the fourth amplifiedoutput signal 90, which is output from thefourth amplifier 74, are summed in thesecond mixer 70. Thesecond mixer 70 outputs thesecond tilt signal 76, which represents the degree of tilt relative to thesecond axis 42. - During
period 67, the voltage appearing across thesecond electrode 22 andfourth electrode 20 is proportional to the tilt of thesensor 32 since there is substantially no influence thereon by thesecond amplifier 68 andfourth amplifier 74, due to their high input impedance in comparison with their output impedance, and the second andfourth electrodes third electrodes period 67, the first amplifiedoutput signal 84, which is output from thefirst amplifier 64, and the third amplifiedoutput signal 86, which is output from thethird amplifier 72, follow thefirst excitation signal 80 and thesecond excitation signal 82, respectively. Thus, when the first amplifiedoutput signal 84 and third amplifiedoutput signal 86 are combined in thefirst mixer 66, the result is substantially zero, which correctly represents a null measurement with respect to thefirst axis 44 during the measurement of tilt with respect to thesecond axis 42. - Although the
tilt sensor 32 formed in accordance with the present invention has been described in terms of measuring a variable voltage caused by variations in resistance between electrodes as representing tilt, it is anticipated that the sensor may respond to variations in voltage, current, capacitance, inductance, impedance, and/or other electrical parameters between electrodes to indicate tilt while remaining within the scope of the present invention. - For example,
FIG. 3 a shows a schematic diagram of a second embodiment of thesignal conditioner circuit 47, which incorporates thetilt sensor 32 shown inFIG. 2 . Thesecond embodiment 47 is similar to thefirst embodiment 46, except that there is preferably only onesignal generator 48, which is connected to each of the three-state drivers mixers - By activating the first enable
signal 60, thefirst signal generator 48 is connected to thefourth electrode 20 and thesecond electrode 22. The amount of current, for instance, is then obtained from the first amplifiedoutput signal 84 and the third amplifiedoutput signal 86 to determine tilt with respect to thefirst axis 44. For example, if the tilt is such that it causes more electrolytic fluid to be in contact with thefirst electrode 18 than thethird electrode 16, then the current reading from the first amplifiedoutput signal 84 will be correspondingly greater than the current reading from the third amplifiedoutput signal 86, the difference between which is calibrated to provide the angle of tilt relative to thefirst axis 44. -
FIG. 7 shows a cross-section of a first embodiment of atilt sensor 92 formed in accordance with the present invention, which includes anelectrode stud 94,header disk 96,seal 98,envelope 100, and conductive medium, such as an electrolyte orelectrolytic solution 102. Anultrasonic seal 103 preferably seals theheader disk 96 to theenvelope 100. Theseal 98 is preferably shaped to fit a counter sunk hole in theheader disk 96 to ensure a longer contact with theelectrode stud 94, but may also be shaped to fill a counter bored hole in theheader disk 96, as shown by dottedlines 101. -
FIG. 8 a shows a side view of theelectrode stud 94 for use in barrel plating, andFIG. 8 b shows a bottom view of theelectrode stud 94 shown in FIG. 7. Theelectrode stud 94 is preferably manufactured or molded from conductive and non-conductive materials, such as polyphenyleneoxide (PPO®) resin, by a two-shot molding process. The first shot preferably forms abody 104 of theelectrode stud 94, which includes four (4) spaced-apartslots 106 that preferably run the length of theelectrode stud 94. Theslots 106 preferably form a mold for the second shot of the process, which includes filling theslots 106 with a conductive material, such as a conductive PPO® resin. The second shot preferably forms four (4) separateconductive traces 108 along the length of theelectrode stud 94. - The conductive traces 108 may or may not be selectively metallized or plated.
FIG. 8 c shows theelectrode stud 94 with an attached break-offstem 91. The break-offstem 91 is preferably used to position theelectrode stud 94 during metallization of theconductive traces 108 by, for example, masking the non-conductive material with a photoresistive material and applying conductive material by vapor deposition or sputtering. Similarly,FIG. 8 d shows arectangular electrode stud 95 with an attached break-offstem 93, which may also have a square or rectangular configuration. The break-offstem 93 is preferably used to position theelectrode stud 94 during metallization of theconductive traces 108 by, for instance electroplating the conductive material. - Alternative methods of making the conductive traces fall within the scope of the invention. For example, the conductive traces may be formed by applying a conductive paint, coating, or other similarly conductive material to the electrode stud, or conductive tape may be applied to form the electrodes. The described methods of forming the electrodes are not intended to limit the scope of the invention and other methods know to those of ordinary skill in the art are contemplated herein.
-
FIGS. 9 a and 9 b show a side cross-sectional view and a top view, respectively, of theheader disk 96, which is preferably shaped as a round disc with asquare hole 110 at its center that may be countersunk or counter bored. Thehole 110 is preferably sized to accept insertion of theelectrode stud 94 therethrough. Thehole 110 is also preferably countersunk or counter bored, as shown inregion 112 to accept insertion of the properly dimensionedseal 98, as shown inFIG. 7 . Anenergy director 105, which is preferably a raised portion of an upper surface of theheader disk 96 that mates with the envelope, is shown inFIGS. 9 a, 9 b, 15 a, 15 b, 16 b, 17 b, and 19 a. Theenergy director 105 is melted during the ultrasonic welding process to form a seal between the header disk and envelope. - The following dimensions are provided in inches and are intended only as an example of an embodiment of the invention and do not in any way limit the scope of the present invention. As shown in
FIGS. 9 a and 9 b,dimension 111 is about 0.100,dimension 113 is about 0.010,dimension 115 is about 0.050,dimension 117 is about 0.200,dimension 119 is about 0.321, anddimension 121 is about 0.110. As shown inFIGS. 10 a and 10 b,dimension 123 is about 0.203, anddimension 125 is about 0.040. As shown inFIG. 11 ,dimension 127 is about 0.300,dimension 129 is about 0.250,dimension 131 is about 0.322,dimension 133 is about 0.372,dimension 135 is about 0.155,dimension 137 is about 0.120, anddimension 139 is about 0.025. -
FIGS. 10 a and 10 b show a side cross-sectional view and a top view, respectively, of theseal 98. Theseal 98 preferably includes ahole 114, which is dimensioned to fit within the countersunk or counterbored region 112 as indicated bydotted lines 111, of theheader disk 96 and around theelectrode stud 94, which is preferably inserted through theheader disk 96. Theseal 98 is also preferably manufactured from a curable material, such as epoxy, and formulated such that when cured it will exhibit approximately the same temperature coefficient of expansion as theelectrode stud 94 andheader disk 96. - A header assembly, which includes the
electrode stud 94,header disk 96, and seal 98, is preferably formed by inserting theelectrode stud 94 through thehole 110 in theheader disk 96 so that theelectrode stud 94 extends from both faces of theheader disk 96 at a proper distance and is positioned such that theheader disk 96 faces upward. Theseal 98 is then preferably oriented to fit around theelectrode stud 94 and into the countersunkregion 112 of theheader disk 96. The header assembly is then preferably placed into an environment having a suitable temperature to cure theseal 98 given an appropriate period of time. Curing of theseal 98 preferably produces a hermetic seal between theelectrode stud 94 and theheader disk 96 in order to retain theelectrolytic solution 102 within theenvelope 100. - The assembly of the
electrode stud 94,header disk 96, and seal are described above as but one example of a method of forming the electrode assembly for the dual-axis, tilt sensor of the present invention. It is contemplated that variations and different manufacturing techniques may be used to form the electrode assembly, which variations fall within the scope of the invention. By way of example, the stud and header disk may be formed as a single component, or other combinations of these components may be combined to form the electrode assembly. -
FIG. 11 shows a side cross-sectional view of theenvelope 100, which is preferably manufactured from a non-conductive material, such as non-conductive PPO® resin. Theenvelope 100 is preferably formed with a cylindrical shape having a round hollow chamber that is closed at one end with a counter bored ortapered hole 116 at the other end. The counter bored ortapered hole 116 is preferably sized to tightly accept the outside circumference of theheader disk 96. - The first embodiment shown in
FIGS. 7-11 is preferably manufactured by positioning theenvelope 100 so that its open end is facing up and injecting theelectrolytic solution 102 into the open space defined by theenvelope 100. The header assembly, which includes theelectrode stud 94,header disk 96, and seal 98, is then preferably properly oriented and forced onto the shoulder of the counterbored hole 116 in theenvelope 100. Theheader disk 96 is then preferably ultrasonically welded around the periphery of the counterbored hole 116 of theenvelope 100. This hermetically seals theelectrolyte 102 within the volume defined by theenvelope 100 and the header assembly. Other methods of sealing the electrode assembly to the envelope or enclosure known to those of ordinary skill in the art, such as adhesives, epoxies, or the like are contemplated by the present invention. - A side cross-sectional view of a second embodiment of a
tilt sensor 118 formed in accordance with the present invention is shown inFIG. 12 . The second embodiment is similar to the first embodiment shown inFIG. 7 , except that the top end of theenvelope 120 includes asmall hole 122 centrally or eccentrically located therethrough, which preferably runs through the top wall of theenvelope 120 and a raisedboss 124 in theenvelope 120. The second embodiment is also different in that theheader disk 96 andelectrode stud 94 are preferably inserted into the counterbored hole 116 of the envelope and aseal 127 is positioned around theelectrode stud 94 and forms a hermetic seal against an outer surface of theheader disk 126 within the counterbored hole 116. -
FIGS. 13 a and 13 b show a side cross-sectional view and top view, respectively, of theheader disk 126. As in the first embodiment, theheader disk 126 includes ahole 128, which is preferably sized to accept theelectrode stud 94 therethrough. Theheader disk 126 shown inFIG. 12 may also include a counter bored, as shown by dottedlines 125, or countersunk region to accept the correspondingly shapedseal 127 as it forms a hermetic seal against an outer surface of theheader disk 126 within the counterbored hole 116 of theenvelope 120.FIG. 14 shows a side cross-sectional view of theenvelope 120, which also includes the counterbored hole 116 sized to accept the outside diameter of theheader disk 126 and seal 127 therein. - The second embodiment is preferably manufactured by positioning the
envelope 120 such that the open counter bored end is facing up so that theelectrode stud 94 andheader disk 126 may be properly oriented and forced into the counterbored hole 116 of theenvelope 120, as shown inFIG. 12 . Theheader disk 126 may then be ultrasonically welded around the periphery of the counterbored hole 116. Theseal 127 may then be applied to the outer surface of theheader disk 126 and cured to provide a hermetic seal. Theelectrolyte 102 is then preferably injected into theenvelope 120 through thetop hole 122 in the center of the raisedboss 124. Thehole 122 is then preferably hermetically sealed with, for instance, heat to retain theelectrolyte 102 within theenvelope 120. -
FIG. 15 a shows an isometric view of a unitary moldedheader 130 for use in a third embodiment of the tilt sensor formed in accordance with the present invention. In the third embodiment, the tilt sensor is produced by a two-shot process. The first shot includes forming the unitary moldedheader 130 to include anelectrode stud portion 132 and aheader disk portion 134 from a non-conductive material, such as PPO® resin. Thestud portion 132 preferably includes spaced-apartslots 136 that run the entire length of theelectrode stud portion 132 and tunnel through theheader disk portion 134. - The spaced-apart
slots 136 preferably form a mold for the second shot of the process, which includes an application of conductive material, such as PPO® resin, to fill each of the preferably four (4)slots 136. The second shot preferably forms four (4) spaced-apartconductive traces 138 through theheader disk portion 134. The conductive traces 138 may or may not be selectively plated or metallized. The remaining components of the third embodiment of the tilt sensor and its assembly may be substantially the same as that described in relation to the first embodiment. -
FIG. 15 b shows an isometric view of a second embodiment of a unitary moldedheader 131 for use in the third embodiment of the tilt sensor formed in accordance with the present invention. The second embodiment of the moldedheader 131 is similar to that shown inFIG. 15 a, except that rather than theslots 133 tunneling through theheader disk portion 135, theslots 133 are preferably directed and form channels along the outside of theheader disk portion 135 as they connect with theslots 133 on opposing sides of theheader disk portion 135. -
FIG. 15 c shows an isometric view of a third embodiment of a unitary moldedheader 137 for use in the third embodiment of the tilt sensor formed in accordance with the present invention. The third embodiment of the moldedheader 137 is similar to that shown inFIG. 15 a, except that theelectrode stud portion 139 andheader disk portion 141 are rectangular or square rather than rounded. -
FIG. 16 b shows a side cross-sectional view of a fourth embodiment of thetilt sensor 140 formed in accordance with the present invention.FIG. 16 a shows a top isometric view of a moldedheader 142 for use in the fourth embodiment of thetilt sensor 140 shown inFIG. 16 b. The fourth embodiment is similar to the third embodiment, except that the moldedheader 142 includes anelectrode stud portion 144 that extends from only one side of theheader disk portion 146. - The opposite side of the header disk portion, from which the
electrode stud portion 146 does not extend, preferably includesconductive pads 148, which are manufactured from, for instance, conductive PPO® resin, that are electrically connected to each of the conductive traces 138 on theelectrode stud portion 144. Theheader disk portion 146 preferably also includesorientation studs 150 that extend from the face of theheader disk portion 146, from which theelectrode stud portion 144 does not protrude. Theorientation studs 150 are preferably mounted within corresponding apertures in, for instance, a printed circuit board to maintain the alignment of the tilt sensor with respect thereto. -
FIG. 16 a shows a side cross-sectional view of the moldedheader 142 mounted within anenvelope 152, in which the electricallyconductive pads 148 face upwards.FIG. 17 a shows a top view of the moldedheader 142 including theorientation studs 150 andconductive pads 148.FIG. 17 b shows a side cross-sectional view of the moldedheader 142 mounted within theenvelope 152.FIGS. 18 a and 18 b show bottom end views of alternative embodiments for theelectrode stud portion 144 shown inFIG. 16 a. -
FIGS. 19 a and 19 b show a side cross-sectional view and a top view, respectively, of a fifth embodiment of thetilt sensor 154 formed in accordance with the present invention. Thetilt sensor 154 preferably includes anenvelope 156 produced by a two-shot molding process. The first shot forms the non-conductivecylindrical envelope 156 having a round hollow chamber that is closed at oneend 151 and counter bored at theother end 153. Theenvelope 156 also preferably includes spaced-apartvertical voids 158 that run the length of theenvelope 156. Thewalls 157 of theenvelope 156 are held in place between thevoids 158 by their attachment to theclosed end 151 of theenvelope 156. - The
voids 158 preferably form a mold for the second-shot, which includes placement of a conductive material, such as PPO® resin, to fill the spaced-apart voids 158. This preferably forms spaced-apartconductive traces 160 along the inside and outside lengths of theenvelope 156. The conductive traces may or may not be selectively plated or metallized. Alternatively, as discussed previously, the electrodes may be formed in the envelope by applying a conductive material thereto in the form of paint, coating, tape, or other suitable method of application known to those of ordinary skill in the art. - The
envelope 156 may also include a protrudingorientation stud 162 adapted to be inserted into a corresponding aperture in, for instance, a printed circuit board, to maintain the position of thetilt sensor 154 after mounting. As shown inFIG. 19 a, thetilt sensor 154 preferably also includes anon-conductive header disk 164 that is sized to fit tightly into the counter bored hole of theenvelope 156. - The
tilt sensor 154 is preferably assembled by positioning theenvelope 156 such that itsopen end 153 is facing upward. Theelectrolyte 86 is then preferably injected into the volume defined by theenvelope 156 and the cover disk orheader disk 164 is forced into and seated onto the shoulder of the counterbored end 153 of theenvelope 156. Theheader disk 164 is then preferably ultrasonically welded around the periphery of the counter bored shoulder to hermetically seal theelectrolyte 86 within theenvelope 156. -
FIG. 20 a shows a side cross-sectional view of a sixth embodiment of thetilt sensor 165 mounted to a printedcircuit board 167. Thetilt sensor 165 is similar to the fifth embodiment, except that the voids of the fifth embodiment have been replaced withslots 169 on an interior surface of theenvelope 156 that preferably extend through only a bottom surface of theenvelope 156. Theslots 169 are preferably filled withconductive material 171 that protrudes from the bottom surface of theenvelope 156 to make electrical contact with acontact arm 173 positioned on theboard 167. - The
tilt sensor 165 also differs from the fourth embodiment in that it includes at least onestud 175, which is preferably molded with theenvelope 156 and protrudes from the bottom surface thereof. Thestud 175 is preferably positioned at the center of the bottom surface of theenvelope 156, as shown inFIG. 20 b, but may be positioned at any other location thereon, as shown inFIG. 20 a, while remaining within the scope of the present invention. Each of thestuds 175 includes a reducedportion 177, which is sized to fit through a hole in the printedcircuit board 167, such that thetilt sensor 165 is held above theboard 167. An end of the reducedportion 177 that extends from the printedcircuit board 167 is preferably heated to form aknob 179 thereon, thereby retaining thetilt sensor 165 in its intended position on theboard 167. Thecontact arm 173 is preferably jogged or elevated from the upper surface of the printedcircuit board 167 by an amount greater than the distance between the protrudingconductive material 171, such that thecontact arm 173 is biased against the protrudingconductive material 171 to ensure adequate electrical connection therewith. -
FIGS. 21 a and 21 b show side and bottom views, respectively, of a sixth embodiment of the four-pin tilt sensor 155 in accordance with the present invention, which includes aglass envelope 159, four (4)wire electrodes 156, andelectrolytic fluid 163. Thetilt sensor 155 is preferably manufactured by methods well known to those skilled in the art, except that the tilt sensor requires only four (4) electrodes to determine tilt with respect to two axes (as discussed above with respect to the signal conditioning circuits shown inFIGS. 3, 3 a, and 4-6. - Thus, the electrolytic tilt sensors formed in accordance with the present invention preferably include one or more of the following features:
-
- 1. components of the tilt sensor are formed from plastics and the like which are readily available, and easy to handle and mold, such as, but not limited to PPO® resin, polypropylene, Vectra® (Celanese Corporation, 1211 Avenue of the Americas, New York, N.Y. 10036), Peak® (Peak Technologies, 9200 Berger Road, Columbia, Md., 21046), Ultem® (General Electric Corporation, One Plastics Avenue, Pittsfield, Mass. 01201), or other suitable materials, and epoxy;
- 2. two-shot molded electrode configurations including a non-conductive first shot to form a base and a conductive second shot to form electrodes, opposing pairs of electrodes being substantially equidistant from each other;
- 3. electrodes may or may not be selectively metallized;
- 4. unitary, integral, or multi-component electrode assembly including the electrode stanchion or stud fitted into the header disk and sealed with an epoxy seal having a temperature coefficient of expansion matched with that of the header disk within a service temperature range of interest, or electrodes molded integrally in the walls of the envelope using a two-shot molding process, thereby reducing the tilt sensor to an envelope and header disk;
- 5. applying the electrodes to the stud or envelope by painting, depositing, and/or taping a conductive material thereto; and
- 6. envelope filled with an electrolyte of suitable volume and hermetically sealed using any known technique, including an ultrasonic weld, adhesive, epoxy, or heating the components to form a seal.
- The tilt sensor embodiments described above are intended as examples without limiting the scope of the present invention in any way, which may incorporate any or all of the features of the exemplary embodiments, as well as the following:
-
- 1. an envelope, electrode stud, header disk, and/or seal having a curvilinear or rectangular, which includes square configuration;
- 2. any or all of the envelope, electrode stud, header disk, and/or seal having the same temperature coefficient of expansion; and
- 3. application of the conductive material to form electrodes by any process known in the art, such as plating, painting, brushing, adhesive, and the like.
- The tilt sensor of the present invention may be mounted to a printed circuit board in any known manner. Several preferred methods for mounting the tilt sensors are shown in
FIGS. 22-25 . Specifically,FIG. 22 a shows a top view of a first embodiment of atilt sensor connector 166 that includes four (4) contactarms 168, which are adapted to electrically connect the conductive traces 108 on theelectrode stud 94 with additional circuitry on, for example, a printed circuit board.FIG. 22 b shows a side cross-sectional view of thetilt sensor 118 inserted into thesensor connector 166 and applied to the printedcircuit board 170. Each of thecontact arms 168 preferably includes asensor portion 172, which makes contact with one of the conductive traces 108 on theelectrode stud 94, and aboard portion 174, which makes contact with circuitry on the printedcircuit board 170. - The
sensor portion 172 andboard portion 174 are connected by a length of thecontact arm 168 that is preferably positioned along a surface of the printedcircuit board 170. Theboard portion 174 is bent such that it can be inserted into an aperture in the printedcircuit board 170 for retention therein by, for example, soldering. Thesensor portion 172 is bent or cantilevered such that it exerts a spring-like tension, as indicated by a dottedphantom 173 of thesensor portion 172, to maintain electrical conductivity with theconductive trace 108 when theelectrode stud 94 is inserted into thesensor connector 166. -
FIG. 23 a shows a top view of a second embodiment of atilt sensor connector 176, which includes four (4) contactarms 178 that are adapted to electrically connect the conductive traces 108 on theelectrode stud 94 with additional circuitry on the printedcircuit board 170 shown inFIG. 23 b. Thetilt sensor connector 176 is preferably manufactured and applied to the printedcircuit board 170 as a single piece with v-notches 180, which can thereafter be stamped to electrically isolate thecontact arms 178 from each other. -
FIG. 23 b shows a side cross-sectional view of theelectrode stud 94 of a tilt sensor mounted in theconnector 176, which has been applied to the printedcircuit board 170. Each of thecontact arms 168 preferably includes asensor portion 182, which makes contact with one of the conductive traces 108. The sensor connector also includes one ormore tabs 184 that are, for example, adapted for being push-fit into holes in the printedcircuit board 170 to maintain the orientation of the tilt sensor. - The
sensor portion 182 is preferably bent such that it exerts a spring-like tension, as indicated by a dottedphantom 173 of thesensor portion 172, to maintain electrical conductivity with theconductive trace 108 when theelectrode stud 94 is inserted into thesensor connector 176. The v-notches 180 are preferably positioned over depressions in the printedcircuit board 170 such that when stamped with a minimal amount of force, the quadrants of thesensor connector 176 are electrically isolated from each other. -
FIG. 24 a shows a top view of a third embodiment of atilt sensor connector 186, which includes four (4) contactarms 188 that are adapted to electrically connect the conductive traces 108 on theelectrode stud 94 with additional circuitry.FIG. 24 b shows a side cross-sectional view of theelectrode stud 94 of a tilt sensor mounted in theconnector 186. The third embodiment of thesensor connector 186 is similar to the second embodiment of thesensor connector 176, except that rounded edges in the second embodiment have been replaced by straight edges in the third embodiment. -
FIG. 25 a shows a top view of a fourth embodiment of atilt sensor connector 190 adapted for use with the sixth embodiment of thetilt sensor 165 shown inFIGS. 20 a and 20 b. Thetilt sensor connector 190 includes four (4) contactarms 192 that are adapted to electrically connect theconductive material 171 protruding from the bottom surface of theenvelope 156 with additional circuitry. Thetilt sensor connector 190 is preferably manufactured and applied to the printedcircuit board 170 as a single piece with v-notches 180, which can thereafter be stamped to electrically isolate thecontact arms 192 from each other. -
FIG. 25 b shows a side cross-sectional view of thetilt sensor 165 mounted in theconnector 190. Each of thecontact arms 192 preferably includes asensor portion 194, which makes contact with the protrudingconductive material 171. The sensor connector also includes one ormore tabs 196 that are, for example, adapted for being push-fit intoholes 198 in the printedcircuit board 170 to maintain the orientation of the tilt sensor. - The
sensor portion 194 is preferably bent such that it exerts a spring-like tension, as indicated by a dottedphantom 200 of thesensor portion 194, to maintain electrical conductivity with theconductive material 171. The v-notches 180 are preferably positioned over depressions in the printedcircuit board 170, such that when stamped with a minimal amount of force, the quadrants of thesensor connector 190 are electrically isolated from each other. - The
sensor connectors sensor connectors electrode stud 94. Following insertion of theelectrode stud 94 in thesensor connectors - Therefore, the present invention provides electrolytic tilt sensors that are small, lightweight, rugged, simple, inexpensive to manufacture, applicable by various automated and non-automated mounting processes, and require fewer electrodes than conventional tilt sensors. The subject tilt sensors are also readily adaptable to mass production techniques within acceptable tolerances for use in a variety of different applications.
- Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention
Claims (73)
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US11/089,187 US7100294B1 (en) | 2005-03-24 | 2005-03-24 | Method of sensing tilt, tilt sensor, and method of manufacturing same |
PCT/US2006/010889 WO2006107622A1 (en) | 2005-03-24 | 2006-03-23 | Method of sensing tilt, tilt sensor, and method of manufacturing same |
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US11/089,187 US7100294B1 (en) | 2005-03-24 | 2005-03-24 | Method of sensing tilt, tilt sensor, and method of manufacturing same |
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US7100294B1 US7100294B1 (en) | 2006-09-05 |
US20060213070A1 true US20060213070A1 (en) | 2006-09-28 |
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US7616100B2 (en) * | 2005-09-16 | 2009-11-10 | Denso Corporation | Antitheft system |
US20070103278A1 (en) * | 2005-09-16 | 2007-05-10 | Denso Corporation | Antitheft system |
US8547662B2 (en) | 2007-08-22 | 2013-10-01 | Kabushiki Kaisha Toshiba | Magnetic recording head and magnetic recording apparatus |
US8654480B2 (en) | 2007-09-25 | 2014-02-18 | Kabushiki Kaisha Toshiba | Magnetic head with spin torque oscillator and magnetic recording head |
US20090316303A1 (en) * | 2008-06-19 | 2009-12-24 | Kabushiki Kaisha Toshiba | Magnetic head assembly |
US8687321B2 (en) | 2008-06-19 | 2014-04-01 | Kabushiki Kaisha Toshiba | Magnetic head assembly |
US8995085B2 (en) | 2008-11-28 | 2015-03-31 | Kabushiki Kaisha Toshiba | Magnetic recording head, magnetic head assembly, magnetic recording apparatus, and magnetic recording method |
US8767346B2 (en) | 2008-11-28 | 2014-07-01 | Kabushiki Kaisha Toshiba | Magnetic recording head, magnetic head assembly, magnetic recording apparatus, and magnetic recording method |
US9129617B2 (en) | 2008-11-28 | 2015-09-08 | Kabushiki Kaisha Toshiba | Magnetic recording head, magnetic head assembly, magnetic recording apparatus, and magnetic recording method |
US9378756B2 (en) | 2008-11-28 | 2016-06-28 | Kabushiki Kaisha Toshiba | Magnetic recording head, magnetic head assembly, magnetic recording apparatus, and magnetic recording method |
US8261458B2 (en) * | 2011-01-26 | 2012-09-11 | Sae Magnetics (H.K.) Ltd. | Geomagnetic sensor device and digital compass with the same |
US20120186091A1 (en) * | 2011-01-26 | 2012-07-26 | Sae Magnetics (H.K.) Ltd. | Geomagnetic sensor device and digital compass with the same |
US9196268B2 (en) | 2012-03-26 | 2015-11-24 | Kabushiki Kaisha Toshiba | Magnetic head manufacturing method forming sensor side wall film by over-etching magnetic shield |
Also Published As
Publication number | Publication date |
---|---|
WO2006107622A1 (en) | 2006-10-12 |
US7100294B1 (en) | 2006-09-05 |
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