Integrated computer display and graphical input apparatus and method

• US 6,061,177 A
• Filed: 12/19/1996
• Issued: 05/09/2000
• Est. Priority Date: 12/19/1996
• Status: Expired due to Fees

• Current Assignee: Kenneth Noboru Fujimoto
• Original Assignee: Kenneth Noboru Fujimoto
• Inventors: Fujimoto, Kenneth Noboru
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): Mahoney, Christopher E.
• Application Number:
  US08/769,997
• Time in Patent Office: 1,237 Days
• Field of Search: 345/157, 345/158, 345/173, 345/175, 345/176, 359/443, 359/453, 359/455, 359/456, 359/457, 359/400
• US Class Current: 359/443
• 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 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

A touch screen input device and method for use with a rear-mounted video output projection system incorporates a transparent sheet preferably having substantially parallel top and bottom surfaces as the touch screen panel. A rear-mounted light source projects light onto the rear surface of the touch screen panel, on which a diffusing surface is imposed, with the result that some of the light from the light source is totally internally reflected within the touch screen panel and is imaged by a rear-mounted video camera. When the front surface of the touch screen panel is touched by a finger or rubbery object, total internal reflection is interrupted and the video camera images the touch as a dark spot. Because the touch screen panel is a sheet having substantially parallel surfaces, the video output system with which the input device is designed to be used is a projection system, and the technology used to detect touches is optical imaging, the touch screen input device can be readily scaled up to desktop or large work-surface sizes. The touch screen input device operates equally well in an environment with any level of ambient light or no ambient light and can simultaneously detect multiple touches. The touch screen input device remains operative while books or other common desktop objects are left resting on portions of the touch screen panel.

Claims

1. A touch screen input device, which comprises:

a transparent sheet having a first surface and a second surface, the transparent sheet having an index of refraction greater than that of air, and the first surface being a smooth surface defining a touch surface of the touch screen input device;

a diffusing surface imposed on the second surface of the transparent sheet;

a light source positioned in proximity to the second surface so that the second surface is closer than the first surface to the light source, and positioned to project light onto the diffusing surface of the transparent sheet, and so that when light is projected onto the diffusing surface some light refracts as said some light passes through the diffusing surface and reflects within the transparent sheet when said some light reaches the first surface; and

a camera positioned in proximity to the second surface so that the second surface is closer than the first surface to the camera, and positioned to image light emanating from the second surface of the transparent sheet;

whereby reflection of light within the transparent sheet is interrupted where the touch surface is being touched and light emanating from the second surface is thereby reduced.

2. The touch screen input device of claim 1, further comprising a video projection system located off the second surface of the transparent sheet and positioned to project light images onto the diffusing surface of the transparent sheet.

3. The touch screen input device of claim 2, further comprising a data computing machine, an interface for performing image processing functions to identify the locations of touches on the touch surface of the transparent sheet, a first data-link connecting the camera to the interface, a second data-link connecting the interface to the data computing machine, and a third data-link connecting the data computing machine to the video projection system so that the data computing machine can provide output data to the video projection system.

4. The touch screen input device of claim 2, wherein the light source is an infrared light source and the camera is an infrared camera.

5. The touch screen input device of claim 2, wherein the light source is an ultraviolet light source and the camera is an ultraviolet camera.

6. The touch screen input device of claim 4, further comprising an infrared blocking filter interposed between the video projection system and the diffusing surface, whereby the infrared blocking filter prevents light from the video projection system from affecting the image data received by the camera.

7. The touch screen input device of claim 5, further comprising an ultraviolet blocking filter interposed between the video projection system and the diffusing surface, whereby the ultraviolet blocking filter prevents light from the video projection system from affecting the image data received by the camera.

8. The touch screen input device of claim 2, further comprising synchronized controllers connected to the light source, camera, and video projection system that turn on and off the light source and the camera, on the one hand, and the video projection system, on the other, in alternating fashion, whereby light from the video projection system does not affect the image data received by the camera.

9. The touch screen input device of claim 2, wherein the light source emits, and the camera receives, only light of a frequency range outside the frequency range projected by the video projection system.

10. The touch screen input device of claim 2, wherein the light source emits, and the camera receives, only light of a given frequency range, and further comprising a blocking filter that blocks light of the given frequency range interposed between the video projection system and the diffusing screen, whereby the light from the video projection system does not affect the image data received by the camera.

11. The touch screen input device of claim 1, further comprising an opaque covering located adjacent the transparent sheet on some portion of the smooth surface of the transparent sheet.

12. The touch screen input device of claim 11, further comprising a processor and a data-link connecting the camera to the processor, wherein the processor includes means for comparing image data from the camera corresponding to the portion of the transparent sheet adjacent the opaque covering with image data from the camera corresponding to the portion of the transparent sheet not adjacent the opaque covering, and means for identifying touches only where the image data corresponding to the portion of the transparent sheet not adjacent the opaque covering represent spots darker than the light level represented by the image data corresponding to the portion of the transparent sheet adjacent the opaque covering.

13. The touch screen input device of claim 1, wherein the transparent sheet is a glass sheet and the diffusing surface is created by sandblasting the second surface of the transparent sheet.

14. The touch screen input device of claim 1, wherein the diffusing surface comprises a plurality of concave lenses formed in the second surface of the transparent sheet.

15. The touch screen input device of claim 1, wherein the diffusing surface comprises a plurality of hemispherical indentations formed in the second surface of the transparent sheet.

16. The touch screen input device of claim 1, wherein the diffusing surface comprises a plurality of convex lenses formed on the second surface of the transparent sheet.

17. The touch screen input device of claim 1, wherein the diffusing surface comprises a plurality of hemispherical bumps formed on the second surface of the transparent sheet.

18. The touch screen input device of claim 1, wherein the diffusing surface is a coating with particles suspended in it applied to the second surface of the transparent sheet.

19. The touch screen input device of claim 18, wherein the particles suspended in the coating are spherical beads.

20. The touch screen input device of claim 1, wherein the diffusing surface is a coating with a varying refractive index.

21. The touch screen input device of claim 20, wherein the coating is a holographic optical element.

22. The touch screen input device of claim 21, wherein the holographic optical element is a photographic emulsion upon which a hologram is exposed.

23. The touch screen input device of claim 21, wherein the holographic optical element is a transparent material upon which a hologram is embossed.

24. The touch screen input device of claim 1, wherein the diffusing surface breaks some of the light rays from the light source into pluralities of rays as the rays refract through the diffusing surface.

25. The touch screen input device of claim 24, wherein the diffusing surface causes some rays of the pluralities of rays to strike the touch surface at angles resulting in total internal reflection within the transparent sheet where the rays strike points on the touch surface adjacent to a layer of air, but does not cause the rays to strike the touch surface at angles resulting in total internal reflection where the rays strike points on the touch surface where a layer of adjacent air has been displaced by a touch.

26. The touch screen input device of claim 25, wherein the total internal reflection within the transparent sheet causes some rays to pass back through the diffusing surface and to be imaged by the camera.

27. The touch screen input device of claim 26, wherein the camera receives images of the areas corresponding to touch spots that are darker than the images the camera receives corresponding to other areas.

28. The touch screen input device of claim 27, wherein the camera provides data that represent the images to an interface for an operating system of a data computing machine.

29. The touch screen input device of claim 1, further comprising a polarizer disposed between the camera and the transparent sheet.

30. The touch screen input device of claim 1, wherein the diffusing surface is created by abrading the second surface of the transparent sheet.

31. A method for identifying where a touch screen of a touch screen input device is being touched, the touch screen input device having a screen panel with substantially parallel top and bottom surfaces, the top surface forming a touch surface and the bottom surface forming a diffusing surface, a light source for projecting light onto the diffusing surface, and an imaging means for imaging light from the bottom surface, the method comprising the steps of:

projecting light onto the diffusing surface of the screen panel using the light source, such that some of the projected light passes through the diffusing surface and is totally internally reflected within the screen panel; and

imaging the projected light that is totally internally reflected within the screen panel and that passes back through the bottom surface of the screen panel with the imaging means, such that areas on the bottom surface that are imaged as relatively dark compared to other areas on the bottom surface are identified as touch areas.

32. A method for providing a reference light level to an imaging means in a touch screen input device, the touch screen input device having a screen panel with substantially parallel top and bottom surfaces, the top surface forming a touch surface having central areas and perimeter areas, and the bottom surface forming a diffusing surface having central areas and perimeter areas that correspond to the central areas and perimeter areas of the touch surface;

a light source for projecting light onto the diffusing surface;

the imaging means for imaging light from the bottom surface; and

an opaque covering positioned on some portion of the perimeter areas of the touch surface such that ambient light does not transmit through the opaque covering, the method comprising the steps of;

projecting light onto the perimeter areas of the diffusing surface of the screen panel corresponding to the portion of the perimeter areas of the touch surface on which the opaque covering is positioned using the light source, such that some of the projected light passes through the diffusing surface and is totally internally reflected within the screen panel and some of the projected light reflects directly off the perimeter areas of the diffusing surface corresponding to the portion of the perimeter areas of the touch surface on which the opaque covering is positioned; and

imaging the projected light that is totally internally reflected within the screen panel and that passes back through the perimeter areas of the diffusing surface corresponding to the portion of the perimeter areas of the touch surface on which the opaque covering is positioned and the projected light that reflects directly off the perimeter areas of the diffusing surface corresponding to the portion of the perimeter areas of the touch surface on which the opaque covering is positioned with the imaging means, such that the imaged light from the perimeter areas of the diffusing surface corresponding to the portion of the perimeter areas of the touch surface on which the opaque covering is positioned provides a reference light level for comparison with imaged light from the central areas of the diffusing surface.