WO2011029107A1

WO2011029107A1 - Display mechanism

Info

Publication number: WO2011029107A1
Application number: PCT/ZA2009/000079
Authority: WO
Inventors: Warren Grobbellar
Original assignee: Integrated Pricing Technologies (Pty) Ltd.
Priority date: 2009-09-03
Filing date: 2009-09-03
Publication date: 2011-03-10

Abstract

A price label which includes a housing with a plurality of indicators which carry symbols and which are individually movable, in a controlled manner, by means o elements of shape memory alloy thereby to present selected symbols through respective windows in the housing.

Description

DISPLAY MECHANISM

BACKGROUND OF THE INVENTION

[0001] This invention relates to a display mechanism.

[0002] In the specification of international application number PCT/ZA2008/000083, there is described a display mechanism which, in one embodiment, makes use of an electric motor, optionally working through a gearbox, which is guided for movement in a selective manner to any of a plurality of indicators and then operated to cause controlled movement of the selected indicator and so vary information displayed by the indicator. This technique is fairly cost effective for it enables a single motor to be used with a plurality of indicators. Nonetheless the cost and reliability of the motor and gearbox, and the requirement for structure to guide movement of the motor to any of a plurality of selected positions, coupled with the provision of appropriate control circuitry, increase the cost and complexity of the final product.

[0003] An object of the present invention is to provide a low cost display mechanism of an alternative and simple construction.

SUMMARY OF THE INVENTION

[0004] The invention provides a display mechanism which includes at least one indicator which is mounted for controlled movement to each of a plurality of discrete positions, a plurality of symbols on the indicator, each symbol being presented for display with the indicator at a respective, associated position, and an actuator to move the indicator, wherein the actuator includes an element formed from a shape memory alloy, and a control circuit for passing current through the element thereby to cause the element to change from a first shape to a second shape and, in the process, to cause movement of the indicator thereby to present a selected symbol for display.

[0005] The element may be connected directly or indirectly to the indicator.

[0006] The actuator may include a restoring device which, upon interruption of current flow through the element, causes the element to revert to the first shape.

[0007] The element may be elongate and, in the first shape, the element may have a first length while, in the second shape, the element may have a second length which is less than the first length.

[0008] The element may lie on a straight line, or follow any appropriate non-linear path and be guided for direction or orientation changes by means of one or more suitably mounted or located devices.

[0009] The restoring device may be a biasing element such as a spring, a weight or the like. The invention is not limited in this regard.

[0010] The indicator may be caused to move in any appropriate way. In one example of the invention, optionally through the use of a plurality of actuators, the indicator is caused to move linearly in one direction or with a reciprocating action, according to requirement. The indicator is however preferably mounted for rotatable movement about an axis. [0011] The indicator may include a disc or similar mechanism mounted for rotation about an axis, with a plurality of ratchet-type formations at a peripheral or exposed surface of the disc and with the actuator positioned to engage selectively with successive ratchet formations thereby to cause rotation of the disc. This arrangement is exemplary only and is non-limiting for the indicator could be in the nature of an elongate flexible band which is mounted between two reels with each reel being selectively movable in a controlled manner by an appropriate respective actuator.

[0012] The symbols on the indicator may be of any appropriate type but, in most applications, will be of an alphanumeric nature.

[0013] The invention also extends to a label or sign which includes a plurality of the display mechanisms positioned within a housing or in appropriate support structure so that selected symbols on the respective indicators are presented for display through one or more windows to make up desired information e.g. a price, a word or the like. The invention is not limited in this respect.

[0014] Techniques described in the specification of international application number PCT/ZA2008/000083 can be used, adopted as appropriate, for transferring data to one or more display mechanisms in order to regulate and control the operation thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is further described by way of examples with reference to the accompanying drawings in which : Figure 1 schematically represents a display mechanism according to one form of the invention,

Figures 2 and 3 illustrate variations of the invention,

Figure 4 shows a display device in the form of an electromechanical price label or the like suitable for use in a retail or similar outlet, and

Figures 5 and 6 illustrate details of an indicator suitable for use in the price label of Figure 4.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0016] Figure 1 of the accompanying drawings illustrates a display mechanism 10 according to one form of the invention which includes a disc-like indicator 12 which is mounted for rotation about a central axis 14. A peripheral surface 16 of the indicator is formed with a plurality of evenly spaced, saw tooth or ratchet formations 18. A plurality of symbols 20 are precisely positioned on a suitable surface 22 of the indicator. In this instance, merely by way of example, the symbols include the numerical characters 0 to 9.

[0017] A designated location 24, referred to herein for the sake of convenience as a window, is defined on appropriate structure which is not affected by movement of the indicator.

[0018] The mechanism includes an actuator 30. An essential part of the actuator is an element 32 formed from an elongate strip of a shape memory alloy. One end of the element is fixed to an anchor point 34. A small ratchet lever 36 is mounted for pivotal movement, to and fro, about a centrally positioned pivot point 38. The pivot point is attached to external structure which is not affected by the movement of the indicator. An end 40 of the element is fixed at an appropriate location to the ratchet lever 36.

[0019] A restoring device 44 acts between the lever 36 and an anchor point. The restoring device is any appropriate component and conveniently is a weight or a simple coil spring.

[0020] The mechanism includes a control circuit 50 which includes a microprocessor, a memory 52 and a power source in the nature of a long-life, low cost battery 54. An external controller 56 which may be hand held by a user, not shown, is capable of transmitting data in a wireless manner e.g. through the use of transmitting techniques operating at infrared or any other suitable frequency, to a receiver 58 which is associated with the processor. If appropriate, data can be transferred from the controller to the control circuit 50 or in the reverse direction.

[0021] Rotation of the indicator disc about the axis 14 will ultimately bring one of the symbols to the window 24. If the remaining portion of the disc is obscured from view then only the selected symbol is available for viewing.

[0022] The control circuit is designed to apply current to the element 32 through flexible electrical conductors 64 and 66 respectively which are connected to opposing ends of the element and to the control circuit. When current flows through the element it contracts, thus altering in shape from a first length to a second length which is shorter than the first length. A force which is thereby exerted is applied to the lever 36 which thus pivots about the point 38 in a rotational direction indicated by an arrow 68. An end of the lever engages with one of the formations 18 and imparts a small angular movement to the disc which moves about the axis 14. At the same time the spring 44 is extended. The control circuit then interrupts the flow of current through the element 32 and the element tends to expand. This action is aided by the restoring effect of the spring 44 which causes the ratchet lever to counter rotate through a small angle in a direction which is opposite to that indicated by the arrow 68. A plurality of current pulses can be given in a controlled manner, regulated by the circuit 50, to the element in order to cause the ratchet lever to engage successively with formations 18. The indicator disc is thus rotated (in this example in a clockwise direction 70) and a desired symbol is then presented for viewing through the window 24.

[002.3] Optical or other sensors 72 responsive to markings on the indicator disc and connected to the control circuit 50 keep track of the actual position of the disc relative to the window 24 and in this way it is possible for the control circuit, using a suitable control program executed by the processor inside the circuit, to regulate movement of the disc so that a desired symbol, consistent with data transmitted to the control circuit from the controller 56, is presented for information.

[0024] The memory 52 is used to store data relating to all aspects of the display mechanism e.g. battery life, an identity number for the mechanism, positional data of the disc, and so on.

[0025] A second ratchet arrangement 74 is, optionally, employed. This ratchet includes a lever 76 which is mounted for a slight degree of reciprocating pivotal movement about a pivot point 78. A small biasing force is exerted on the lever by an external spring 80. The ratchet mechanism allows clockwise rotation of the indicator disc, for the described type of operation. When the restoring device 44 functions there may however be a tendency, due to frictional forces, for the disc to counter rotate. The ratchet arrangement 74 prevents this from happening.

[0026] The rotational movement of the indicator disc is thus accomplished by repeatedly causing the element 32 to contract and expand. The element is significantly cheaper than a miniature motor of the kind used in the electromechanical price label described in the specification of international application number PCT/ZA2008/000083. It is completely silent in operation and has a robust nature and a long life. The contraction/expansion of the element is readily controlled and this property can thus be used in an effective way to cause rotational movement of the indicator disc.

[0027] Figure 2 shows a mechanical arrangement 90 which forms part of a display mechanism according to a variation of the invention. An indicator 12B, which in one embodiment is disc-like, is mounted for rotation about an axis, not shown. At a peripheral or exposed location a plurality of evenly-spaced saw-tooth formations 18B are provided. Symbols are carried by the indicator and, upon movement of the. indicator in a manner which is described hereinafter, a selected symbol is presented for viewing through a window, not shown. In this respect the invention is similar to what has been described in connection with Figure 1.

[0028] An elongate element 32B of shape memory alloy is anchored to fixed structure at one end 34B and is then passed over a number of pins or rollers 92, mounted to fixed structure. An end 40B of the element is fixed to an end of a ratchet lever 36B which, in turn, is mounted for pivotal movement about a pivot point 38B. 000079

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[0029] An electric circuit, not shown, which is similar to that shown in Figure 1 , is connected to the mechanical arrangement. The circuit generates a voltage under controlled conditions which is applied between the ends 34B and 40B of the element. When this occurs the element contracts and the ratchet lever is pivoted in a direction 94 against the action of a spring 44B which is thereby extended. A free end 96 of the ratchet lever engages with one of the teeth 18B and the indicator 12B is thereby moved though a small increment in the direction of an arrow 98. When the electric current is interrupted the restoring action of the spring causes the ratchet lever to return to the position shown in Figure 2.

[0030] The teeth 18B can be provided on a peripheral edge of a rotatable disc or on a side of a disc. Alternatively the indicator 12B can be elongate and can be mounted for reciprocating sliding movement along a linear path. In this instance repeated actuations of the ratchet lever cause the indicator 12B to move further and further in the direction 98.

[0031] If the indicator is to be moved in a direction which is opposite to the direction 98 then the indicator is provided with a plurality of saw-tooth formations 18BB which are oppositely disposed to the formations 18B. In addition, components which are counterparts to those shown in the upper half of Figure 2 are provided on the lower side so that, when actuated, the indicator is moved to the left. In this movement the free end 96 of the ratchet lever 36B rides over the tips of the saw-tooth formations 18B. Frictional drag which could be created in this respect can be obviated entirely by arranging the ratchet lever 36B to be moved by the restoring action of the spring 44B to a position at which the ratchet lever is sufficiently displaced from the indicator so that movement of the indicator is not obstructed.

[0032] The convoluted shape memory alloy element 32B has a considerable length, which enables greater movement to be obtained when contraction takes place. The pins/rollers 92 however provide a space-efficient mounting configuration for the element.

[0033] Figure 3 illustrates another arrangement 10C which makes use of the movement principle which has been described but which is of a more complex nature. In this instance two reels 120 and 122 respectively are mounted for rotation about respective axes 124 and 126. An elongate flexible band 128 of any appropriate material carries a plurality of desired symbols 130. Upon rotation of the reels in one direction or the other the band is moved correspondingly and a selected symbol can thus be positioned for viewing through a window 132 formed in adjacent fixed structure 34.

[0034] The reel 120 can be moved in one direction by an actuator 30C which is similar to the actuator 30 described in connection with Figure 1. Similarly the reel 122 can be counter rotated, to cause the band to move in an opposing direction by means of an actuator 30D which is positioned to cause counter movement of the band.

[0035] Figure 4 shows a practical implementation of the principles of the invention in the construction of an electromechanical price label 150. The price label includes a small housing 152 in which are positioned a number of display mechanisms 154A, 154B ...154N. Each display mechanism is generally of the kind shown in Figure 5 (front view) and Figure 6 (side view) and includes a main circular body 156 which is mounted for rotation about a horizontal axis 158. The body has a fairly broad peripheral edge 160 on which symbols of any appropriate kind are marked at spaced intervals. A relatively smaller circular body 62 is formed integrally with, or otherwise is attached to, the body 156. Saw-tooth formations 164 are formed on a periphery of this body. An electric circuit 166, generally of the kind shown in Figure 1 , is positioned to act on the formations 164 in order to cause rotation of the indicator in a controlled manner about the axis 158.

[0036] A front side 170 of the housing has a number of spaced windows 172 and the indicators 154A ...154N of the display mechanisms are positioned so that a selected symbol on each respective indicator can be presented for viewing through an associated window. Each display mechanism is independently actuable by its respective control circuit and shape memory alloy element. This can be done using the principles described in the specification of PCT/2IA2008/000083, the content of which is hereby incorporated into this specification.

[0037] The electromechanical price label shown in Figure 4 is significantly cheaper than a label which makes use of an electrical motor and gearbox arrangement to cause selected symbols to be displayed. The label requires energy only to position the symbols for display and thereafter the display is continuous without further energy consumption.

Claims

1. A display mechanism which includes at least one indicator which is mounted for controlled movement to each of a plurality of discrete positions, a plurality of symbols on the indicator, each symbol being presented for display with the indicator at a respective, associated position, and an actuator to move the indicator, wherein the actuator includes an element formed from a shape memory alloy, and a control circuit for passing current through the element thereby to cause the element to change from a first shape to a second shape and, in the process, to cause movement of the indicator thereby to present a selected symbol for display.

2. A display mechanism according to claim 1 wherein the actuator includes a restoring device which, upon interruption of current flow through the element, causes the element to revert to the first shape.

3. A display mechanism according to claim 1 wherein the element is elongate and follows a non-linear path.

4. A display mechanism according to claim 1 wherein the indicator is mounted for rotatable movement about an axis.

5. A display mechanism according to claim 4 wherein the indicator includes a disc mounted for rotation about an axis, with a plurality of ratchet-type formations at a peripheral or exposed surface of the disc and with the actuator positioned to engage selectively with successive ratchet formations thereby to cause rotation of the disc. A display mechanism according to claim 1 wherein the indicator is an elongate flexible band which is mounted between two reels with each reel being selectively movable in a controlled manner by an appropriate respective actuator.

A label which includes a plurality of display mechanisms, each display mechanism being according to claim 1 , and a housing to which the display mechanisms are mounted so that selected symbols on the respective indicators are presented for display through one or more windows in the housing to make up desired information.

A price label which includes a housing with a plurality of indicators which carry symbols and which are individually movable, in a controlled manner, by means of elements of shape memory alloy thereby to present selected symbols through respective windows in the housing.