Passive Touch System And Method Of Detecting User Input

• US 20070075982A1
• Filed: 08/31/2006
• Published: 04/05/2007
• Est. Priority Date: 07/05/2000
• Status: Active Grant

• Current Assignee: Smart Technologies Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Smart Technologies Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Morrison, Gerald, Singh, Manvinder
• Granted Patent: US 7,755,613 B2
• Time in Patent Office: Days
• 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 method of aligning a plurality of digital cameras in a touch system, each digital camera having a selectable pixel array with respect to a region of interest in front of a touch surface of the touch system on which a pointer contact is made, said method comprising the steps of:

acquiring an image of said region of interest;

examining pixels within a subset of said pixel array to determine if the pixel subset is substantially looking along the plane of said touch surface; and

if not,

adjusting the position of said pixel subset and repeating said acquiring and said examining steps until a pixel subset is determined that looks substantially along the plane of said touch surface.

2. The method of claim 1, wherein during said examining, pixels within said pixel subset are examined to determine if said pixels include data referencing said touch surface.

3. The method of claim 2, wherein said data comprises a tip of said pointer in contact with said touch surface.

4. The method of claim 2, further comprising the step of determining the row of pixels within said pixel subset when data corresponding to the tip of said pointer in contact with said touch surface exists.

5. A touch system comprising:

a substantially rectangular touch surface;

a region of interest that is in front of, and at least partially includes, said touch surface; and

a digital camera mounted adjacent at least three corners of said touch surface, said digital cameras being oriented to capture overlapping images of said region of interest.

6. A touch system according to claim 5, wherein each said digital camera comprises a CMOS digital camera.

7. A touch system according to claim 6, wherein each digital camera has a selectable pixel array.

8. A touch system according to claim 7, wherein said digital cameras are oriented so that the field of view of each digital camera extends beyond a peripheral edge of said touch surface.

9. A touch system according to claim 8, further including a processor associated with each of said digital cameras, each digital camera and associated processor being mounted on a common board.

10. A touch system according to claim 9, wherein a subset of pixels in the selectable pixel array of each digital camera provides pixel data to said associated processor.

11. A touch system according to claim 10, wherein each pixel subset includes contiguous rows of pixels.

12. A touch system according to claim 11, 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.

13. A touch system according to claim 12, wherein the row 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.