GB2161266A

GB2161266A - Switch device

Info

Publication number: GB2161266A
Application number: GB08515584A
Authority: GB
Inventors: Antonis Chris Ioannides
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-07-02
Filing date: 1985-06-19
Publication date: 1986-01-08
Also published as: GB8515584D0; GB2161266B

Abstract

A switch device mounts a radiation source 7 and a radiation sensor 9 so that when the device is placed against a screen 12 transparent to the radiation the presence or absence of a finger F or other operating element at a predetermined location on the other side of the screen determines whether or not the sensor 9 receives sufficient radiation to provide an electrical output. The finger or operating element may itself create the path for the radiation between the source and the sensor directly or it may move a reflective element (Fig 3) to create or destroy such path. Fixed reflective elements on the other side of the screen (Fig 4) may provide a portion of a radiation path which can be interrupted by the finger or operating element; and an array of such path portions may be provided and the associated sensors repetitively scanned so that a symbol traced within the array can be recognised. <IMAGE>

Description

SPECIFICATION Switch device The invention relates to a switch device and more specifically to a switch device arranged to be actuated in response to the presence or absence of an operating element from a predetermined location.

A variety of switch devices which do not depend on a mechanical drive input from the operator to change condition have been developed, but such devices are self-contained and are ill-adapted to installation in locations in which the devices could be usefully employed.

According to the present invention there is provided a switch device comprising a support which mounts a radiation source and a radiation sensor so that when the device is placed at one side of a screen or window transparent to the radiation, the radiation sensor provides, or ceases to provide, an electrical output,or changes its electrical condition, in dependence on the presence or absence at a predetermined location on the other side of the screen of a finger or other operating element.

The invention can embodied in a switch device in which light or other radiation is emitted from the source through the transparent sheet continuously or in pulses during use of the device and is received by the sensor, or is received by the sensor in significant intensity, only when an operating element is so located at the other side of the sheet as to reflect light from the source onto the sensor.

The support means can mount a plurality of such associated sources and sensors in adjacency to provide a keyboard or data entry device. The device is conveniently arranged so that the operating element is the user's forefinger. The keyboard device can be readily located on the inner side of an existing transparent screen, for example a shop window or a window of a building or a vehicle, and the user can input data by way of the device to associated equipment for example display and/ or control equipment. Thus when installed in a shop window, the device of the invention can respond to predetermined inputs to cause the associated equipment to display information and/or to responde in any of a variety of ways. Installed in a glazed door, the device can respond to appropriate inputs to open the door or allow it to be opened.

The switch or keyboard device is thus physically separated from the operating location by the transparent sheet material against which the operator can be guided to place his finger at the appropriate location by a mark carried by the device. Although the device of the invention is preferably arranged to be self-contained on one side of the radiation transparent screen, it can include co-operating means for location on the other side of the screen, such means incorporating reflecting elements movable to alter the radiation intensity reaching the sensor or defining a radiation path which can be interrupted by the operator, and an array of the devices can then be arranged so as to respond to predetermined finger positions within a prescribed area.

The invention is further explained in the following illustrative description with reference to the accompanying drawings, in which: Figure 1 shows in schematic sectional side view a first switch device in accordance with the present invention in operative association with a transparent sheet; Figure 2 is a schematic perspective view of an array of switch devices in accordance with the invention again in operative relation with a transparent sheet; Figure 3 is a schematic sectional side view of a modified switch device in accordance with the invention; Figure 4 is a partial schematic sectional side view of a third switch device embodying the invention; and Figure 5 is a partial perspective view of the switch device of Figure 4.

The switch device of the invention shown in Figure 1 comprises support means in the form of a mounting block 2 of opaque material, for example, an opaque plastics material, having a plane face 3.

The mounting block 2 has two bores 5,6 extending therethrough, with adjacent openings at the face 3.

One bore 5 has its axis substantially normal to this face and contains a light emitter or source 7 in the form of a light emitting diode (LED). The axis of the bore 6 is inclined at an acute angle to the axis of the bore 5 and contains, at a position spaced from the face 3, a light detector or sensor 9 in the form of a photodiode. The light source 7 and the sensor 9 are connected to circuitry 10 including a source of pulses by which the light source is energised at an appropriate high frequency. The circuitry 10 also includes means responsive to the output level of the sensor, which depends on the intensity of the light incident on it, to produce an appropriate output signal, applicable for such purposes as have been indicated above.

The switch device and the circuitry 10 together comprise a self-contained unit which unit is however designed to function not on its own, but in association with a screen of transparent material in the form of a sheet 12 of glass or plastics material, against one side of which the face 3 of the support means is located. The switch device can be simply placed in proximity to the sheet 12 or can be secured to it, or to a frame within which it is held,in any suitable way. During the periods of energisation of the light source 7, light is transmitted from the source through the sheet 12 within a divergent cone of say 20 angle. A certain amount of the transmitted light is scattered and internally reflected within the sheet 12 and some of this light will reach the sensor 9 as background noise.

However, the exposed surface of the sheet 12, that is, the surface remote from the mounting block 2, is accessible for operation of the switch device as by application of a finger F to a particular position on the exposed surface as indicated. The axis along which the sensor 9 lies, which corresponds to the axis of the bore 6, is inclined to the face 3 to detect light reflected at the point at which the light beam impinged on the outer surface of the sheet 12. The configuration of the switch device and the thickness of the sheet 12 are such that sufficient scattered light from the source 7 then reaches the sensor 9 for a change in the sensor output to be detected by the circuitry 10. The positions and angular dispositions of the source 7 and sensor 9 are selected to be appropriate to a useful range of thicknesses of the sheet 12.

The use of pulsed energisation of the light source assists in minimising the effects of stray ambient light, and these effects are further minimised by the spacing the light sensor 9 from the face 3 of the mounting block. The light source 7, can be positioned in the mounting block 2 so that the axis of the light beam it emits, instead of being normal to the surface 3 as shown is inclined to that surface, so that light received by the sensor 9 due to spurious reflections and light scattering will be minimised.

Normally, the switch device of the invention will not be used singly but will be in association with a plurality of like devices, in a keyboard or other data input assembly. Thus, Figure 2 shows a keyboard or data input device 20 containing three rows of the switch devices 21 in accordance with the invention, each of which can correspond to the device of Figure 1, so as to be operable by application of the finger F to the exposed side of the sheet 12. The signals derived from the various sensors 9 are supplied to circuitry in the device 20, which can include a microprocessor, in which, after conversion to digital form, they are treated to provide outputs for control andsor display purposes.

Although the outer surface of the sheet 12 can carry appropriate graphics material, such as alphanumeric symbols and the like, to indicate the position which the operator should apply his finger, it is preferred for such material to be carried on the face 3, as indicated at 2 on Figure 2, so that the keyboard or switch device can be put in use simply by being placed with the surface 3 against one side of the sheet 12.

Although the invention is preferably embodied in a switch device which can be put into use by being located simply against one side of an existing transparent sheet, it is within the invention to provide switching means comprising two co-operating units which are secured in use on opposed sides of the transparent sheet. For example, as shown in Figure 3, there is applied to the exposed side of the sheet 12, a member 30 of resiliently deformable plastics material, transparent to the radiation and having embedded therein an element 31 with a reflective surface opposite the sheet. The source 7 and the sensor 9 are received in bores in the mounting block 2 with axes at substantially 45" to the plane face 3 which converge at a position short of the element 31.In the normal condition of the member 30, shown at the upper part of Figure 3, any light the element receives from the source is reflected away from the sensor. However, finger pressure applied to the member 30 resiliently distorts the member, as shown in the lower part of Figure 3, thereby shifting the position of the element 31 so that a substantial amount of the light is reflected onto the sensor. Release of the finger pressure permits the resilience of the member 30 to return the element 31 to its original position, so that the output of the sensor 9 drops to its previous level.An array of such elements 31 can of course be employed with the device 20 of Figure 2 As shown in Figures 4 and 5, a data input device embodying the invention comprises a unit 40 for mounting perpendicular rows of light sources 7 forming two sides of a rectangle 41, the other two sides of which are defined by perpendicular rows of sensors 9. Applied to the exposed side of the sheet 12 is a frame 42 (not shown in Figure 5) positioning a rectangular array of reflective elements in the form of prisms 44 so that a beam of light from a source 7 transmitted normally through the sheet 12 is internally reflected through 90" by one prism 44 or other reflective means so as to traverse the rectangle 41. At the remote side of the rectangle, the beam is reflected by another prism 44 or other means normally through the sheet 12 to a sensor 9.A grid of light beams thus traverses the rectangle 41.

The sources are energised in pulses and the out puts of the sensors 9 are continuously scanned by circuitry included in the unit 40 to detect any interruption of a light beam such as would occur if a finger were placed against the sheet 12 within the rectangle 41. As two light beams are interrupted the position of the finger can be related to the perpendicular axes represented by two perpendicular sides of the rectangle. Repeated scanning of the sensor output enables movement of the finger within the rectangle 41 to be traced and the resultant output can be compared with data stored in the circuitry so that a particular symbol or group c symbols traced by the finger can be recognised to trigger a desired control function.

It will be evident that the invention can be embodied in a variety of ways other than as specifically described and illustrated.

Claims

1. A switch device adapted to be placed again one side of a screen transparent to radiation and t be operable from the other side thereof, the devio comprising support means mounting a radiation source capable of emitting the radiation and a radiation sensor responsive to the radiation to provide an electrical output, the support means mounting the source and the sensor at positions such that with the device juxtaposed to the screer reception of the radiation by the sensor to cause the sensor to provide the output is dependent on the presence of a finger or other operating eleme at a predetermined location on the other side of the screen.

2. A switch device as claimed in claim 1 wherein the support means comprises a block of opaque material having a plane face for juxtaposi tion with the one side of the screen, and first and second holes therein extending to the plane face and receiving therein the sensor and the source n spectively.

3. A switch device as claimed in claim 2 wherein the first hole receiving the sensor has an axis inclined to the plane face and the second hole receiving the source has an axis substantially perpendicular to the plane face.

4. A switch device as claimed in claim 2 wherein the first and second holes have respective axes each inclined at substantially 45" to the plane face.

5. A switch device comprising a source of radiation, a sensor arranged to provide an electrical output in response to incidence of the radiation thereon, and support means having a plane face and mounting the source and the sensor so that the source can emit the radiation through the plane face, the sensor can receive the radiation through the plane face, and, when the device is placed at one side of a screen transparent to the radiation, the sensor provides an output when a finger or other operating element at a predetermined position on the other side of the screen establishes or interrupts a path for the radiation from the source to the sensor by way of the screen.

6. A switch device as claimed in claim 5 so arranged that the sensor output is obtained in response to the juxtaposition of the operating element and the other side of the screen at the predetermined position.

7. A switch device as claimed in claim 5 having at the other side of the screen a pressure responsive unit arranged to establish or interrupt the path in response to pressure from an operating element thereon.

8. A switch device as claimed in claim 7 wherein the pressure responsive unit comprises a reflective element and a resiliently deformable member transparent to the radiation and having the reflective element received therein, the member being deformable by manual pressure to move the reflective element to establish or interrupt the path.

9. A switch device as claimed in claim 5 further comprising two reflective elements being spaced apart at the other side of said screen to define therebetween a portion of the path located for interruption by the operating element.

10. A switch device as claimed in any one of claims 2-9 having graphics material located on the plane face.

11. A switch device as claimed in any one of claims 2 -10 wherein the mounting means mounts the sensor at a position therein spaced from the plane face.

12. A switch device as claimed in any preceding claim having means for energising the source intermittently whereby the radiation is emitted in pulses at high frequency.

13. A switch device as claimed in any one of claims 1 -11 located in adjacency with a plurality of like switch devices, a circuit device being connected to the switch devices to constitute therewith a keyboard or data input device.

14. A switch device comprising a source of radiation, a member transparent to the radiation, means mounting the radiation source on one side of the member for transmission of the radiation through the member, a sensor arranged to change an electrical condition thereof in response to reception of the radiation thereby, means mounting the sensor on the one side of the member for reception of the radiation through the member, and first and second reflective means mounted on another side of the member opposed to the one side in spaced positions such that the first reflective member reflects the radiation received from the source to the second reflective member and the second reflective member reflects the radiation to the sensor, whereby the electrical condition of the sensor can be changed by interruption of the radiation reflected between the first and second reflective means.

15. A switch device as claimed in claim 14 having a plurality of like switch devices located in adjacency thereto with the first and second reflective elements of the switch devices arranged in parallel rows, and circuit means associated with the switch devices for scanning the sensors to recognise a pattern traced by a finger or other operating element moved between the rows.

16. A switch device as claimed in claim 15 having a second plurality of like switch devices located with the first and second reflective elements thereof in spaced parallel rows extending across respective ends of the first-mentioned rows.

17. A switch device substantially as herein described with reference to Figure 1, Figure 2, Figure 3 or Figures 4 and 5 of the accompanying drawings.

18. Any novel feature or novel combination of features herein described.