Passive touch system and method of detecting user input

• US 8,378,986 B2
• Filed: 07/01/2010
• Issued: 02/19/2013
• Est. Priority Date: 07/05/2000
• Status: Expired due to Term

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Morrison, Gerald, Singh, Mavinder
• Primary Examiner(s): Liang, Regina
• Application Number:
  US12/829,175
• Publication Number:
  US 20100265202A1
• Time in Patent Office: 964 Days
• Field of Search: 345/156, 345/157, 345/168, 345173-179, 178/18.01, 178/18.09
• US Class Current: 345/173
• CPC Class Codes: G06F 3/042 by opto-electronic means
• 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
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A passive touch system includes a passive touch surface and at least two cameras associated with the touch surface. The at least two cameras acquire images of the touch surface from different locations and have overlapping fields of view. A processor receives and processes images acquired by the at least two cameras to detect the existence of a pointer therein and to determine the location of the pointer relative to the touch surface. Actual pointer contact with the touch surface and pointer hover above the touch surface can be determined.

Claims

1. A touch system comprising:

a substantially rectangular frame configured to surround a region of interest in front of a display surface;

at least two digital cameras, each digital camera having a selectable pixel array and being mounted adjacent a different corner of said frame, each digital camera having a field of view that extends at least beyond a peripheral edge of said frame, said digital cameras being oriented to capture overlapping images of said region of interest; and

at least one processor processing a subset of pixel data of images captured by the digital cameras to detect the existence of a pointer therein, said at least one processor further processing image data of each digital camera to compensate for an angle between a field of view of each digital camera and at least a portion of said periphery of said frame as a reference.

2. A touch system according to claim 1, wherein each said digital cameras comprises a CMOS digital camera.

3. A touch system according to claim 2, further including a processor associated with each of said digital cameras, each digital camera and associated processor being mounted on a common board.

4. A touch system according to claim 3, wherein a subset of pixels in the selectable pixel array of each digital camera provides pixel data to said associated processor.

5. A touch system according to claim 4, wherein each pixel subset includes contiguous rows of pixels.

6. A touch system according to claim 5, wherein the pixel subset of each digital camera is aligned so that the pixel subset of each digital camera looks substantially along the plane of said touch surface.

7. A touch system according to claim 6, wherein the rows of pixels in the pixel subset of each digital camera, that acquires pixel data corresponding to a tip of said pointer on said touch surface, is determined to enable said processor to detect pointer contact with said touch surface and pointer hover within said region of interest.

8. A touch system according to claim 1, wherein said at least one processor controls image-taking parameters of said digital cameras.

9. A touch system according to claim 8, wherein the controlled image-taking parameters comprise at least one of exposure, gain, array configuration, reset, initialization, and frame rate.

10. A touch system according to claim 1, wherein the at least one processor further locates the pointer by triangulation.

11. A touch system comprising:

a substantially rectangular frame configured to surround a region of interest in front of a display surface;

at least two imaging devices, each imaging device having a selectable pixel array and being mounted adjacent a different corner of said frame, said imaging devices being oriented so that the field of view of each imaging device extends at least beyond an adjacent peripheral edge of said frame, said imaging devices capturing overlapping images of said region of interest; and

at least one processor processing a subset of pixel data of images captured by the imaging devices to detect the existence of a pointer therein, said at least one processor further processing image data of each imaging device to compensate for an angle between a field of view of each imaging device and at least a portion of said periphery of said frame as a reference.

12. A touch system according to claim 11, wherein each imaging device comprises a CMOS digital camera.

13. A touch system according to claim 12, further including a processor associated with each of said imaging devices, each imaging device and associated processor being mounted on a common board.

14. A touch system according to claim 13, wherein a subset of pixels in the selectable pixel array of each digital camera imaging device provides pixel data to, said associated processor.

15. A touch system according to claim 14, wherein each pixel subset includes contiguous rows of pixels.

16. A touch system according to claim 15, wherein the pixel subset of each imaging device is aligned so that the pixel subset of each imaging device looks substantially along the plane of said touch surface.

17. A touch system according to claim 16, wherein the row of pixels in the pixel subset of each imaging device, that acquired pixel data corresponding to a tip of said pointer on said touch surface, is determined to enable said processor to detect pointer contact with said touch surface and pointer hover within said region of interest.

18. A touch system according to claim 11, further including a processor associated with each of said imaging devices, each imaging device and associated processor being mounted on a common board.

19. A touch system according to claim 11, wherein said at least one processor controls image-taking parameters of said imaging devices.

20. A touch system according to claim 19, wherein the controlled image-taking parameters comprise at least one of exposure, gain, array configuration, reset, initialization, and frame rate.

21. A touch system according to claim 11, wherein the at least one processor further locates the pointer by triangulation.