US 3603983 A
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Primary Examiner+Robert L. Richardson Att0mey-Westell & Hanley  MECH ANlCAL-ELECTRICAL CODE GENERATING DEVICE EMPLOYING FLUID SWITCHING ABSTRACT: A mechanical-electrical code generating device d, fluid carrying tubes, each having in which a plurality of close 340/365, pressure responsive means for producing a unique electrical 178/17 C, ZOO/81.4, 235/145 R, 235/200 signal, are selectively compressible to generate a selected pat- G08c 19/00 tern of signals.
ll Claims, 7 Drawing Figs.
[5 1] Int. Cl.
PATENIEDSEP 7I97l 35039 3 SHEET 1 OF 2 FIG. 1
WILLIAM MITCHELL PATENTEDSEP mn (503,9 3
sum 2 or 2 I N VLiN'l'OR.
WILLIAM MITCHELL MECHANICAL-ELECTRICAL CODE GENERATING DEVICE EMPLOYING FLUID SWITCHING The present invention relates to a mechanical-electrical code generating device and more particularly to the digitally selective generation of coded electrical signals.
In the manual transcribing of information onto paper it is usual to use a keyboard, for example a typewriter. The same keyboard concept has been used to transduce mechanical energy into electrical energy for information storage and transmission, for example in a teletype machine. Keyboards presently in use for the mechanical-electrical transduction of energy are relatively expensive to produce and maintain. Furthermore, variations in the arrangement of the keys on the keyboard are obtainable only at considerable further expense.
It is an object of the present invention to provide an improved device, using fluid-pressure means, for the digitally selective generations of coded electrical signals.
It is another object of the invention to provide an improved keyboard device for generating a unique code for each operated key.
A further object of the invention is to provide a keyboard device, for generating coded electrical signals, in which the replacement of keys is simplified.
An example embodiment of the invention as shown in the accompanying drawings in which:
FIG. 1 is a schematic plan view of a keyboard employing the present invention; 1
FIG. 2 is a face view in elevation taken along the line 2-2 of FIG. 1, showing a key and tube arrangement;
FIG. 3 is a side view in elevation taken along the line 33 of FIG. 2;
FIG. 4 is a view similar to FIG. 2 showing the key depressed to generate a coded signal and a bumper tube;
FIG. 5 is a side view in elevation taken along the line 55 of FIG. 4, showing in phantom the further depression of the key 'to generate a strobe signal;
FIG. 6 is a side view of a pressure-actuated switch for use with the invention, connected to a signal tube; and
FIG. 7 is a side view in elevation showing a bumper tube.
In the drawings, FIG. 1 shows a keyboard 10 comprising a housing 11 carrying on its upper portion a faceplate l2 and rows of keys or pushbuttons 13, for example as used in teletype operations. As shown in FIGS. 2 and 3, each key 13 is loosely retained in an aperture 14 of faceplate 12 and projects both above and below the faceplate with the upper projecting portion carrying indicia.
A belt 15' underlies faceplate 12 within housing 11 and consists of a plurality of closed signal tube 16 lying parallel one to another in a horizontal plane and each terminating in a fluidactuated, pressure-sensitive switch 17. As seen in FIG. 1, belt 15 follows a sinuous path in order to pass beneath all keys 13 of keyboard 10.
As shown in FIGS. 2 and 3 of the drawings, key 13 comprises a cap 18 resting in aperture 14, and a key plate 19 extending downwardly from the cap into lower portion 20 of housing 11 and transverse to belt 15. Cap 18 consists of an inverted cup 21 having a circumscribing lip 22 which engages the underside of faceplate I2, and a guide member 23 fixed to cup 21 to form a chamber 24 in the cap. Guide member 23 projects downwardly to form a shoulder 25. Key plate 19 slides vertically in a slot 26 formed in member 23 and in the wall of chamber 24, and is urged downwardly by compressive means comprising a compression spring 27 which bears at one end against a depression 28 in the bottom of cup 21 and at the other end against a shoulder 29 on the key plate. A vertical slot 30 is carried by key plate 19 and accommodates a pin 31 mounted in member 23 transverse to slot 30, which retains the key plate in slot 26 against the action of spring 27.
The lower portion of key plate 19 is crenellated to provide a plurality of fingers 32 defining slots 33 of two different lengths in predetermined sequence, the sequence being different for each key. Each slot 33 accommodates a tube 16 of belt 15 which rests in a passage 34 in lower portion 20 of housing 11. Fingers 32 of key plate 19 are vertically slidable, along with the lower portion of the key plate, in a slot 35 in body portion 20 which terminates at its lower end in a further passage 36 carrying a bumper tube 37. One of fingers 32, preferably a central finger 32a, is positioned to move against bumper tube 37 which runs parallel to belt 15 and beneath the belt. Bumper tube 37 is sealed at both ends as shown in FIG. 7, and is filled with noncompressible fluid in an amount which allows squeezing of the tube by only one key at a time. A strobe tube 38 rests on base portion 20 of housing 11 above belt 15 and parallel to it, and passes through a vertical slot 39 in each key plate 19.
In the described embodiment, central finger 32a rests against bumper tube 37 and hence key 13 rides on the bumper tube when the key is in a position of rest. Compression spring 27 is of sufficient stiffness to yield only after tubes 16 have been compressed by key plate 19 and, conversely, tubes 16 are of sufficient transverse resilience that they yield to compression by key plate 19 before spring 27 yields. Bumper tube 37 must be of sufficient transverse stiffness to hold each key 13 in a position of rest but resilient enough to yield to compression by one key. Each tube 16 is closed at both ends, one end terminating in a flexible membrane 40 which contacts a plunger 41 in fluid-actuated switch 17, as seen in FIG. 6. Plunger 41 in turn bears against a spring contact 42 of a pair of normally open contacts 43 of switch 17. Tube 16 is filled with a noncompressible fluid 44 such as water (i.e. noncompressible under normal operating pressure of key 13). Strobe tube I 38 is also closed and filled with noncompressible fluid, and carries a pressure-sensitive switch 17 at one end, in the same manner as tubes 16 shown in FIGS. 6 of the drawings.
In the operation of cause example embodiment, the depression of a key 13 will cause certain of tubes 16 to be squeezed as shown in FIGS. 4 and 5, leaving the remainder of the tubes unaffected. The squeezing of any one of tubes 16 by its associated key plate 19 displaces fluid 44 laterally in the tube and the pressure of displacement acts against membrane 40 to force plunger 41 against spring contact 42, thus closing contacts 43 of switch 17. The depression of key 13 at the same time squeezes bumper tube 37 as shown in FIG. 4, 5 and 7. Because bumper tube 37 is sealed at both ends and can be compressed only to a certain extent, not more than one key 13 can be depressed at any one time, thus preventing overlapping signals from being generated in switches 17.
Because of the resistance of tubes 16 and 17 after they have been squeezed, the further depression of key 13 causes further compression of spring 27 and brings shoulder 25 of member 23 into contact with strobe tube 38. Continued downward depression of key 13, and increased compression of spring 37 during completion of the key stroke, causes the strobe tube 38 to be squeezed by shoulder 25 of member 23, as seen in phantom lines in FIG. 5 of the drawings, and a strobe signal is generated to indicate that the operation of the key is completed. The presence of the strobe signal also indicates that the code signal corresponding to the operated key should be read from the state of allswitches 17 associated with tubes 16 during the time that the strobe signal is present. This ensures that false code signals are not generated due to partial key operations which operate some of the switches 17 associated with tubes 16 but which are not sufficient to generate the strobe signal.
By providing different patterns of slots 33 inv keys 13, different signal patterns may be generated in switches 17. The example embodiment described above, illustrated key 13 generates an 8-bit code with the pattern of FIG. 4 signalling 10101011 to identify the particular character carried by the face of that key.
It will be seen that the device of the present invention enables keys 13 to bearranged in any suitable manner since each key generates a unique code when operated. For the same reason individual keys 13 can-be removed and replaced in keyboard without any adjustment in base portion carrying tubes 16 in housing 11 and this allows the keyboard to be adapted to any desired code arrangement with little expense in parts and labor.
l. A mechanical-electrical code generating device comprising:
a plurality of substantially parallel, contiguous, transversely resilient, closed tubes, each of the tubes carrying a noncompressible fluid;
means responsive to a change of pressure of the fluid in each of the tubes to produce, for each tube, an electrical signal; and l a plurality of actuating means positioned transversely to the tubes and each adapted to compress the tubes selectively whereby the pressure responsive means is actuated.
2. A device as claimed in claim 1 in which the actuating means comprises a key having a member positioned transversely to the tubes and crenellated to provide slots receiving the tubes, the slots being of different lengths for selectively compressing the tubes on depression of the key.
3. A device as claimed in claim 2 in which the crenellated member comprises a plate slidable in the key and movable against compressive means mounted on the key and remote from the slots, the compressive means being yieldable when the selected tubes have been compressed, and including a closed, transversely resilient strobe tube carrying a noncompressible fluid and compressible by the key when the compressive means yields, the strobe tube having means connected therewith adapted to produce an electrical signal on compression of the strobe tube by the key.
4. A device claimed in claim 1 in which the pressure-responsive means comprises a plurality of pressure-actuated switches, one switch being connected with each of the tubes.
5. A device as claimed in claim 1 including a closed, transversely resilient bumper tube actuable by any of the actuating means and substantially filled with a noncompressible fluid whereby only one of the actuating means is operable at one time.
6. A device as claimed in claim 1 including a closed, transversely resilient strobe tube carrying a noncompressible fluid and actuable by any one of the actuating means, and means responsive to a change in pressure of the fluid in the strobe tube to produce an electrical signal, the strobe tube being actuable after the selected ones of the plurality of tubes have been compressed.
7. A mechanical-electrical device for the digital selection of coded electrical signals, comprising:
a plurality of transversely resilient, closed tubes lying in parallel relationship one with another, each of the tubes carrying a noncompressible fluid therein;
a keyboard having a plurality of keys each having a member located transverse to the tubes and crenellated to receive the tubes one in each slot formed thereby, the slots being of a selected pattern of lengths whereby on depression of the key and movement of the member transverse to the tubes selected ones of the tubes are simultaneously compressed; and
means actuable on a change of pressure of the fluid in each of the tubes to generate a code unique to the selected combination of tubes compressed.
8. A mechanical-electrical device for the digital selection of coded electrical signals, comprising:
a housing having a base portion and a keyboard mounted on the base portion;
a plurality of transversely resilient, closed tubes lying in parallel relationship in a common plane and supported by the base portion of the housing, each of the tubes carrying a noncompressible fluid therein;
a plurality of keys mounted on the keyboard, each key having a member positioned transverse to the tubes and crenellated to receive the tubes one in each slot formed thereb the slots being of a selected pattern of depth where y on depression of the key and movement of the member across the plane of the tubes selected ones of the tubes are simultaneously compressed; and
a plurality of pressure-actuated switches one connected with an end of each of the tubes and actuable on a change of pressure of the fluid in each of the tubes to generate a code unique to the selected combination of tubes compressed.
9. A device in claim 8 including compressive means mounted on the key and bearing against the crenellated member remote from the slots, the crenellated member being slidable in the key and the compressive means being yieldable when the selected tubes have been compressed, and a closed, transversely resilient strobe tube supported by the base portion of the housing and carrying a noncompressible fluid, the Strobe tube being compressible by the key when the compressive means yields and having means connected therewith adapted to produce an electrical signal on compression of the strobe tube by the key.
10. A device as claimed in claim 9 in which the key comprises a cap having a chamber therein and a guide member mounted on the cap, the crenellated member being slidable in the guide member and into the chamber, and the compressive means comprises a compression spring mounted in the chamber with one end of the spring bearing against the cap and the other end of the spring bearing against the crenellated member, the guide member having a shoulder engageable with the strobe tube on compression of the spring.
1 1. A device as claimed in claim 8, including a closed, transversely resilient bumper tube supported by the base portion of the housing the bumper tube being compressible by any one of the keys and being substantially filled with a noncompressible fluid whereby only one the keys is operable at one time.