GB2317490A

GB2317490A - Matrix display; Controllable valve

Info

Publication number: GB2317490A
Application number: GB9619543A
Authority: GB
Inventors: Ivan Nicholas White
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-09-19
Filing date: 1996-09-19
Publication date: 1998-03-25
Anticipated expiration: 2016-09-19
Also published as: GB2317490B; GB9619543D0

Abstract

A matrix display comprises an array of rods 12 each of which is has one end that is visible. Each rod 12 is associated with a linear actuator arranged to cause controlled longitudinal motion of an associated rod. The linear actuator is a return spring 18 acting on the rod in opposition to pressure applied to the rod by a variable flow gas supply. The return spring can be a coiled spring or a silicone rubber or other elastomeric member. A constant pressure air supply operating through a controllable valve provides the variable flow rate gas supply. The valve comprises two plates 28,32 each having slits 30, 34 the plates being relatively movable so that the slits can be moved into and out of register with each other. The plates are moved against a spring bias 36 by a nickel titanium wire 38 which expands and contracts in dependence on an electric current flowing therein.

Description

DISPLAY APPARATUS The present invention relates to display apparatus. It provides a new form of display intended to allow visual effects that were not previously possible. The display can be used for a wide range of purposes, such as advertising, corporate displays, and artistic presentations.

It therefore provides a display apparatus comprising an array of elongate rods, and an array of linear actuators, one actuator being associated with each rod, each actuator being adapted to cause controlled longitudinal motion of the rod.

The cross-sectional shape of the rod is not particularly important, but a circular or hexagonal shape is usually easiest to embody. For reasons which will become apparent, the invention is easier to embody if the rods are lightweight, and this is therefore a preferred feature. More preferably, the rods are formed of a plastics material.

Preferably, the array of rods is supported in a corresponding array of elongate recesses of compatible cross-section.

The linear actuator of a preferred form of the invention comprises a return spring acting on the rod in opposition to a variable displacement force. Preferably, the return spring acts to withdraw the rod into the recess. The return spring can be a coil spring1 or an elastomeric member such as an elongate length of silicone or other rubber material.

In a particularly preferred form of the invention, the variable displacement force is provided by a variable flow rate gas supply applied to the rear of the rod. The variable flow rate gas supply can be provided by a constant pressure air supply which communicates with the rear of the rod via a controllable valve. The constant pressure air supply is preferably in the form of a chamber maintained at a constant pressure.

The valve referred to above preferably comprises a first valve member containing apertures and a second valve member movable relative to the first and which also contains apertures which are hence movable into and out of register with those on the first, the second valve member being biased relative to the first by a biasing means, for example a spring, and a variable force member acting in opposition to the biasing means. The variable force member can be nickel-titanium wire through which a variable current is passed. Nickel-titanium wire expands and contracts with changing temperature, and therefore will expand and contract as the current therein changes.

An embodiment of the present invention will now be described by way of example, with reference to the accompanying Figures, in which: Figure 1 is a front view of the device; Figure 2 is a section on II-II of Figure 1; Figure 3 is an enlarged view of an individual element of Figure 2; and Figure 4 is an illustration of a valve.

Referring to Figure 1, this shows a display apparatus 10 which comprises a large array of rods 12 which protrude slightly from the front of the display 10. Figure 2 shows the display 10 and rods in section, and it can be seen that the circular rods 12 are retained in elongate recesses 14. The recesses 14 have a rear stop 16 which limits the rearward movement of the rods 12. The rear face of the rods 12 are connected to an elongate silicone rubber band which is fixed to an anchoring point 20 deeper within the recess 14.

The recesses 14 communicate with a chamber 22 which is supplied via an inlet 24 with air at a constant pressure. Such could be supplied by a centrifugal fan, for instance.

Figure 4 shows details of the valve 26. This consists of a back plate 28 in which is formed an array of slits 30. A blanking plate 32 overlies the slits, but itself has a second array of slits 34 formed therein in a corresponding fashion. The blanking plate 32 can slide back and forth relative to the back plate 28, by virtue of overlapping guides 31, 33. In its rest position, shown in Figure 4, the two pairs of slits are not in register and hence the valve is closed. The blanking plate 32 is held in its rest position by a return spring 36 which is attached at one end to the blanking plate 32 and at another end to the back plate 28. It can be pulled away from its rest position by a nickel-titanium (NiTi) wire 38. NiTi wire contracts longitudinally with increasing temperature, and can therefore be used as a simple mechanical actuator. The shape change can be up to 4.5%, which through suitable design of dimensions is capable of providing a sufficient effect.

Changes in temperature in the NiTi wire are achieved by passing an electric current therethrough. Therefore, the spring 36, blanking plate 32 and NiTi wire 38 are electrically connected and conductive thereby to form a single flow path for electric current between two terminals 40, 42.

It may be advisable to add a flexible wire between the blanking plate 32 and the terminal 40, to short circuit the spring. Terminal 40 is grounded to the base plate 28, enabling a single wire connected to terminal 42 to allow for control of temperature of the NiTi wire and hence positioning of the valve.

To use the apparatus, a supply of air at constant pressure is introduced at the inlet 24. When it is desired to extend a particular rod, current is supplied to the terminal 42 associated with that particular rod and this causes the unstressed length of the NiTi wire 38 to reduce. This causes the blanking plate 32 to be pulled against the action of the spring 36 until the spring 36 and NiTi wire 38 achieve a balance at which the tensions in each element are equal. At this point, the respective slats 30, 34 will overlap to a greater or lesser extent, allowing an air flow into the region behind a rod 12 (Figure 3). This air flow will escape via outlet valve 17, but the predetermined dimension of outlet 17 means that a certain pressure will form in that region. The pressure that forms will be that which is sufficient to cause an air flow out of the outlet 17 equal to the air flow in via valve 20. This pressure will be exerted on the rear face of the rod 12, and will exert an outward force thereon. The rod 12 will hence move outward, increasing the tension in the band 18, until the air pressure on the rear of rod 12 equals that tension. At this point, the rod will be in equilibrium.

As the current in the NiTi wire 38 is varied, so the position of the blanking plate 32 will vary and hence the flow rate achieved will vary.

This will hence vary the pressure behind the rod, and therefore the extent of its extension.

It is then a simple matter to provide for computer control of the current flowing in each NiTi wire 38 of the entire array. This then provides control of the extent of projection of each rod 12 in that array.

Control of the current in the NiTi wires 38 can be via control of the magnitude of that current, or preferably, by pulse width modulation of a constant current.

It can be seen from Figure 2 that the region 22 is sufficiently large to provide a reservoir of air under pressure which will therefore be unaffected by the opening and closing of an individual valve 20. The region is also sufficiently large to allow access to the array of valves for repair or replacement of an individual valve at the end of its working life.

As illustrated, the array is vertical with the rods extending horizontally. This is the simplest arrangement, since the weight of the rods is supported. However, the apparatus can be adapted for use in other orientations. If vertical, some compensation for the weight of the rods will ideally be provided. If the rods project upward, this could be done by forming a permanently open aperture in parallel to the valve 20 which will provide a permanent baseline air flow to support the rod weight.

If the rods project vertically downward, then a pre-tensioning of the bands 18 should be sufficient.

The above embodiment is described by way of example only, and many variations can be made thereto whilst remaining within the scope of the present invention. Thus, whilst it is intended that the apparatus be about 3m square and contain approximately 6,000 rods of about 35mm diameter, each able to extend by approximately one metre, this is not essential and the apparatus can be built to any design size.

Claims

1. Display apparatus comprising an array of elongate rods, and an array of linear actuators, one actuator being associated with each rod, each actuator being adapted to cause controlled longitudinal motion of the rod.

2. Display apparatus according to claim 1 wherein the cross-sectional shape of the rod is circular or hexagonal.

3. Display apparatus according to claim 1 or claim 2 wherein the rods are formed of a plastics material.

4. Display apparatus according to any preceding claim wherein the array of rods is supported in a corresponding array of elongate recesses of compatible cross-section.

5. Display apparatus according to any preceding claim wherein the linear actuator comprises a return spring acting on the rod in opposition to a variable displacement force.

6. Display apparatus according to claim 5 wherein the return spring acts to withdraw the rod into the recess.

7. Display apparatus according to claim 5 or claim 6 wherein the return spring is a coil spring.

8. Display apparatus according to claim 5 or claim 6 wherein the return spring is an elastomeric member.

9. Display apparatus according to claim 5 or claim 6 wherein the return spring is an elongate length of silicone.

10. Display apparatus according to any one of claims 5 to 9 wherein the variable displacement force is provided by a variable flow rate gas supply applied to the rear of the rod.

11. Display apparatus according to claim 10 wherein the variable flow rate gas supply is provided by a constant pressure air supply which communicates with the rear of the rod via a controllable valve.

1 2. Display apparatus according to claim 11 wherein the constant pressure air supply is provided by a chamber maintained at a constant pressure.

1 3. Display apparatus according to claim 11 or claim 1 2 wherein the valve referred comprises a first valve member containing apertures and a second valve member movable relative to the first and which also contains apertures which are hence movable into and out of register with those on the first, the second valve member being biased relative to the first by a biasing means and a variable force member acting in opposition to the biasing means.

14. Display apparatus according to claim 13 wherein the variable force member is a nickel-titanium wire through which a variable current is passed.

1 5. Display apparatus substantially as herein described with reference to and/or as illustrated in the accompanying figures.