Deformable touch sensitive surface

• US 4,542,375 A
• Filed: 02/11/1982
• Issued: 09/17/1985
• Est. Priority Date: 02/11/1982
• Status: Expired due to Term

• Current Assignee: NCR Corporation
• Original Assignee: AT&T, Inc.
• Inventors: Alles, Harold G., Kubik, Peter S.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/347,877
• Time in Patent Office: 1,314 Days
• Field of Search: 340/712, 340/365 P, 340/709, 340/815.31, 340/365 VL
• US Class Current: 345/176
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/037 using the raster scan of a cathode-ray tube [CRT] for detecting the position of the member, e.g. light pens cooperating with CRT monitors
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A touch sensitive device is arranged with substantially parallel surfaces inside which light from a synchronized source, such as a CRT, can become trapped by total internal reflection. The screen is fitted with photodetectors which respond to the entrapment of light within the surfaces. The device is compliant so that a touch of the device at a particular point will cause an inward deflection of the surface at that point. The deflection causes light to become entrapped within the surface by total internal reflection thus making it possible, by comparing the photodetector output with the CRT raster position, to determine the exact surface position of the touch.

Claims

1. A touch sensitive device for use in conjunction with a signal source, said device comprising

spaced apart surfaces arranged such that signals are introduced between said surfaces so as to become entrapped within said device by total internal reflection between said surfaces as a result of a deformation of one of said surfaces of said device relative to the other of said surfaces, and

signal utilization means adapted to provide a distinctive output when said signals are so introduced between said surfaces.

2. The invention set forth in claim 1 wherein a portion of said signals pass through said surfaces.

3. The invention set forth in claim 1 wherein said surfaces are substantially parallel to each other prior to said touch and wherein the inner side of said deformed surface forms a convex surface with respect to said signals.

4. The invention set forth in claim 1 further comprising

means for coordinating the position of said signal across said surfaces of said device with said distinctive output to determine the exact position on said surface of said touch.

5. The invention set forth in claim 1 wherein said signal source is a CRT and wherein said signals which are introduced into said device are light signals from said CRT and wherein means are positioned between said device and CRT to insure the presence of an air gap even when said surface is touched.

6. The invention set forth in claim 2 wherein said light utilization means includes at least one light detecting diode.

7. The invention set forth in claim 2 wherein said light utilization means includes optic fibers.

8. Deflection detection apparatus for use with a signal source, said apparatus comprising

a compliant structure having spaced apart surfaces such that signals from said signal source are introduced by total internal reflection between said surfaces as a result of a compression of said structure.

9. Deflection detection apparatus comprising, in combination, a signal source, and

a compliant structure having spaced apart surfaces such that signals from said signal source are introduced by total internal reflection between said surfaces, as a result of a compression of said structure.

10. A position sensitive total internally reflective device for use in conjunction with a source of light, said device comprising

substantially parallel surfaces arranged such that light from said light source impinging upon one of said surfaces is subject to a changeable light ray angle within said surfaces due to an inward deformation of said one surface, and

light utilization means arranged to provide a distinctive output only when said impinging light is subjected to said changed light ray angle so as to become entrapped within said device by total internal reflection between said surfaces of said device.

11. The invention set forth in claim 10 further comprising

means for coordinating the position of said light across said surfaces of said device with said distinctive output to determine the exact position on said one surface of said touch.

12. The invention set forth in claim 10 wherein said utilization means includes at least one light detecting diode.

13. The invention set forth in claim 10 wherein said detecting diode is mounted adjacent an edge of said parallel surfaces and where said edge is coated white.

14. The invention set forth in claim 10 wherein said device is a deformable material at least 1/8 inch thick having the property that one surface may be deformed inward while the opposite surface remains relatively undeflected.

15. A touch position sensitive total internally reflective device adapted for mating with the screen of a CRT operable for generating light patterns on the surface thereof, said light patterns being coordinately positioned under control of repetitive vertical and horizontal inputs, said device comprising

a flexible sheet of transparent material having inner and outer surfaces substantially parallel to each other through which light from said mated CRT screen passes,

at least one light utilization means operable for providing outputs indicative of the magnitude of the light impinging on said utilization means and positioned so that light which impinges thereupon comes substantially from within said device between said parallel surfaces, and so that when said outer surface of said device is flexed inward at a point thereon said utilization means output reflects such deflection for a period of time corresponding to the time when said light is being generated at said point of flexure.

16. The invention set forth in claim 15 wherein said device is a flexible material at least 1/8 inch thick having the property that one surface may be deflected inward while the opposite surface remains relatively undeflected.

17. A device for use in combination with the screen of a CRT, said CRT operable for generating light images on the screen thereof, said light images occurring as a result of a horizontal and vertical scan of an electron beam directed against said screen, said device including

a sheet of material having inner and outer surfaces through which light generated at said CRT screen will pass with a refraction angle φ

1 at said inner surface next to said CRT screen and with a refraction angle φ

2 at said outer surface,

light utilization means operable for providing an output representative of the magnitude of light which impinges on said light utilization means, and

positioned such that said impinging light comes substantially from between said surfaces of said device and such that when said refraction angle φ

2 is changed to refraction angle φ

3 said light utilization means output reflects said angle change, said refraction angle φ

3 being such that total internal reflection occurs, said refraction angle φ

3 being a result of an inward flexure of said outer surface of said device.

18. The invention set forth in claim 17 wherein said photodetecting means includes first and second photodiodes having different spectral sensitivities.

19. The invention set forth in claim 17 further comprising means positioned between said CRT and said device for maintaining an air gap between said inner surface and said CRT even when said outer surface is flexed.

20. A CRT having a touch position sensitive total internally reflective screen, said screen comprising

substantially parallel outer and inner surfaces arranged such that signals are introduced between said surfaces as a result of a flexure of said outer surface relative to said inner surface of said screen, and,

signal communicating means arranged to provide a distinctive output when said signals are introduced between said surfaces by a touch of said outer-surface so as to become entrapped within said screen by total internal reflection of said surfaces of said screen.

21. The invention set forth in claim 20 further comprising

means for coordinating the ordinate position of said signal across said screen with said distinctive output to determine said position on said screen of said touch.

22. A CRT operable for generating light images on the screen thereof, said light images occurring as a result of a horizontal and vertical scan of an electron beam directed against said screen, said CRT including

a screen having inner and outer parallel surfaces through which light generated by said electron beam will pass with a refraction angle φ

1 at said inner surface and with a refraction angle φ

2 at said outer surface,

light utilization means arranged for providing an output representative of the magnitude of light which impinges on said utilization means, and positioned such that said impinging light comes substantially from between said surfaces of said screen and such that when said refraction angle φ

2 is changed to a refraction angle φ

3 said utilization means output reflects said angle change, said refraction angle φ

3 being the critical angle for total internal reflection to occur, and said refraction angle φ

3 being a result of a flexure of said outer surface of said screen relative to said inner surface.

23. A touch sensitive device for use in conjunction with a signal source, said device comprising

a layer bounded by two spaced apart surfaces arranged such that signals may be introduced between said surfaces, said layer having one of said surfaces deformable with respect to the other of said surfaces whereby signals introduced via one of said surfaces and having an angle φ

1 with respect to said surfaces as a result of a deformation of the other of said surfaces relative to said one surface, said deformation changing the angle of said signal from φ

1 to φ

2 with respect to said other surface, and

means for detecting said entrapped signals and producing a signal in response thereto.