GB2263765A

GB2263765A - Touch screen systems

Info

Publication number: GB2263765A
Application number: GB9201824A
Authority: GB
Inventors: Paul Philip Oliver
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-01-25
Filing date: 1992-01-25
Publication date: 1993-08-04
Also published as: GB9201824D0

Abstract

A touch screen system includes a display screen 1 behind a window 4, beam transmitters 7, beam detectors 14, and reflective surfaces 9, 11 mounted in front of the window. A matrix of beams 5 passes from the transmitters 7, through the window 4, and are reflected across the face of the window, back through the window, and detected by the detectors 14. The beams intersect in a matrix array in front of the window, and breaking of the beams at any point of intersection is detected. <IMAGE>

Description

Title: Imorovements in or relating to Touch Screen Svstems Field of the Invention: The invention relates to touch screen systems. Particularly systems which are located in explosive or hazardous environments. However, the invention is also applicable to touch screen systems in which it is desirable to isolate the person interacting with the systems from the electronics of the system.

Background to the Invention Touch screen systems are known in which a matrix of optical beams are arranged to traverse the face of a television or computer screen so that when two of the beams are interrupted this occurrence is sensed and the interrupted x and y coordinates which are interrupted identify a unique location on the screen. The unique location is associated with information or options which may be selected by pointing a finger at the relevant unique location.

Generally, a bank of infra-red or light emitting diodes (LED) direct a series of parallel beams across the face of the screen so that the signals are detected by a bank of light-signal receivers which are monitored to detect when the beam from the corresponding LED is interrupted.

The LED and light receivers are in "line-of-sight" in front of the screen.

It will be appreciated that if the touch screen system is located in an explosive or hazardous environment the electronics of the LED and light receivers is in front of the screen and, under fault conditions, this can cause an explosion or fire.

Such an arrangement also provides the opportunity for the electronics of the system to be interfered with by a user.

The present invention seeks to provide a touch screen system which isolates the electronics of the system from the user and the local environment.

Summarv of the Invention According to a first aspect of the invention there is provided a touch screen system including a screen upon which information is arranged to be displayed at preset locations, which are arranged to be uniquely identified by a matrix of beams. Said beam being reflected across the face of a transparent window in front of the screen and reflected onto receivers located behind the window.

According to a second aspect of the invention there is provided a touch screen system including a screen upon which information is arranged to be displayed at preset locations, which are arranged to be uniquely identified by a matrix of beams emanating from a number of beam transmitters located behind a transparent window which isolates the touch screen system from the environment, and a number of beam receivers each arranged to receive one of the beams and to provide an output to a detector circuit which identifies when the beam has been interrupted, characterised in that the beam from each of the light transmitters is directed onto a reflecting surface which redirects the beam across the face of the screen to impinge on a second reflective surface arranged to redirect the beam onto a corresponding one of the beam receivers.

Summarv of the Drawings The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing in which:- Figure 1 shows a schematic view of a touch screen system; and, Figure 2 shows a perspective cut away view of part of the system.

Specific Description Referring now to the drawings, figure 1 shows a screen 1 of a cathode ray tube 2 which is arranged to display information in a known manner from a driver circuit and associated electronics 3. The screen 1 is located immediately adjacent a transparent window 4. A matrix of beams 5 is arranged to traverse the face of the window 4.

The beams are emitted by a set of light emitting diodes (LED) 6 mounted on a unit 7 and powered from a control circuit 8. The beams from the LED 6 are directed through the window 4 to a mirror 9 held in a mounting 10 at 45" to the window 4. The beam is reflected from the mirror 9 across the face of the screen 1 to impinge on a mirror 11 mounted at 45 in a mounting 12. The beam is reflected from the mirror 11 onto a corresponding one of beam receiving detectors 13 mounted in a unit 14 which is coupled to a detecting circuit 15. The entire electronics of the touch screen system is sealed by a casing 16 onto the window 4.

It will be appreciated that the system is shown schematically and that there is a further set of LED and receivers to provide the orthogonal grid or matrix of beams necessary to uniquely distinguish the positions adjacent to relevant information on the screen. The similar set of transmitters, receivers and mirrors have been given the same reference numerals but with a superscript to indicate the y coordinate.

Referring now to figure 2 it will be seen that the beams 5 and 5' intersect at a point 17. When the beams are interrupted by a finger the light paths are prevented from reaching the receivers 13 and 13' and this uniquely identified point 17 and the relevant screen information associated with this point It will be appreciated that the system may be used in a shop or banking premises as it permits the isolation of the customer from the electronic circuitry of the touch screen system by the interposition of the window 4. The system also has a particular application in hazardous and explosive environment as it permits the complete electronics to be incased by the casing 16 and window 4 so that any hot or sparking components within the system are isolated from the hazardous environment.

Care should be taken in positioning the mirrors so that the beam can be maintained as a narrow beam accurately reflected by the mirrors onto the receivers. The mirrors may be incorporated within a frame mounted on a window and the frame may be substantially the size of the screen 1. If necessary the light emitting diodes need not be located directly below the mirror but offset so that the beams emerge obliquely from the window 4. In such cases the angle of the mirror will not be 45" but adjusted so that the beam is parallel to the surface of the window and just above it.

In certain applications it may be advantageous to stagger the set of LEDs and beam receivers so that two or more grid patterns are created at differentiating heights above the window 4. Such an arrangement may be used to confirm the unique location and to prevent false signals which may occur by flies or other material falling on the window.

It will be appreciated that the principle of isolating the user from the touch screen system may be adapted for many applications which permit mirrors to be located on the user side of the window so that the user may be isolated from the electronics of the touch screen according to the principle of the invention.

Claims

1 A touch screen system which includes a screen upon which information is to be displayed at preset locations, which locations are arranged to be uniquely identified by a matrix of beams, said beams being reflected across the face of a transparent window in front of the screen and reflected onto receivers located behind the window.

2 A system according to claim 1 wherein the matrix of beams emanates from a plurality of beam transmitters located behind a transparent window which isolates the touch screen from its environment, and the beam receivers are each arranged to receive one of the beams to provide an output to a detector circuit which identifies where the beam has been interrupted, characterised in that the beam from each of the beam transmitters is directed onto a reflecting surface which redirects the beam across the face of the screen to impinge on a second reflective surface arranged to redirect the beam onto a corresponding one of the beam receivers.

3 A system according to claims 1 or 2 wherein the beam transmitters are light emitting diodes.

4 A system according to claims 1 or 2 wherein the beam transmitters are infra-red emitting diodes.

5 A system according to any of the preceeding claims wherein the reflecting surfaces are mounted at an angle of 45 degrees to the front surface of the window.

6 A system according to any of the preceeding claims wherein the beams are parallel with the front surface of the window on passing from the first reflective surface to the second reflective surface.

7 A system according to any of the preceeding claims wherein the beams intersect orthogonally.

8 A system according to any of the preceeding claims wherein the electronic circuitry and cathode ray tube are isolated from the environment by a casing.

9 A system according to any of the preceeding claims wherein the beam detector circuit is operatively connected to the cathode ray tube.

10 A touch screen substantially as herein described with reference to the accompanying drawings.