Touch system and method for determining pointer contacts on a touch surface

• US 20040178993A1
• Filed: 03/11/2003
• Published: 09/16/2004
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Smart Technologies Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Morrison, Gerald D., Singh, Manvinder, McCharles, Randy, Tseng Su, Scott Yu
• Granted Patent: US 6,947,032 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

A system and method for determining pointer contacts on a touch surface includes a touch surface to be contacted by a pointer. At least one imaging device having a field of view looks generally along the touch surface. At least one processor communicates with the at least one imaging device and analyzes images acquired by the at least one imaging device to detect the relative positions of a pointer and a reflection of the pointer therein and thereby determine if a pointer contact with the touch surface has been made.

Claims

1. A method of determining pointer contact with a touch surface comprising the steps of:

capturing an image using an imaging device having a field of view oriented obliquely with respect to said touch surface; and

processing the captured image to detect a pointer and a reflection of the pointer therein and determine if the detected pointer and reflection meet signifying pointer contact with said touch surface.

2. The method of claim 1 wherein during said processing, pixels in said captured image are examined to determine if empty pixels separating the detected pointer and said reflection exist signifying non-pointer contact with said touch surface.

3. The method of claim 2 wherein during said processing, rows of said pixels are examined to determine if empty pixel rows separating the detected pointer and said reflection exist signifying non-pointer contact with said touch surface.

4. The method of claim 3 wherein said imaging device has a field of view looking across said touch surface and wherein said rows of pixels are horizontal.

5. The method of claim 2 further including the step of providing backlighting for said imaging device during image capture, said pointer and reflection being represented by non-illuminated pixels in said captured image, empty pixels being illuminated.

6. The method of claim 1 wherein during said processing a pixel subset of said captured image is processed.

7. The method of claim 6 wherein during said processing, pixels in said pixel subset are examined to determine if empty pixels separating the detected pointer and said reflection exist signifying non-pointer contact with said touch surface.

8. The method of claim 7 wherein during said processing, rows of said pixels are examined to determine if empty pixel rows separating the detected pointer and said reflection exist signifying non-pointer contact with said touch surface

9. The method of claim 8 wherein said imaging device has a field of view looking across said touch surface and wherein said rows of pixels are horizontal.

10. The method of claim 7 further including the step of providing backlighting for said imaging device during image capture, said pointer and reflection being represented by non-illuminated pixels in said pixel subset, empty pixels being illuminated.

11. The method of claim 10 wherein said imaging device has a field of view looking across said touch surface and wherein said rows of pixels are horizontal.

13. The method of claim 10 wherein during said processing, pixels in said captured images are examined to determine if empty pixels exist between a detected pointer and reflection signifying pointer hover.

14. The method of claim 13 wherein during said processing, rows of pixels in said captured images are examined.

15. The method of claim 13 wherein pointer contact is determined when images captured by each of said imaging devices signify pointer contact with said touch surface.

16. The method of claim 13 wherein pointer contact is determined when images captured by one of said imaging devices signifies pointer contact with said touch surface.

17. The method of claim 16 wherein said one imaging device is the imaging device closest to said pointer that captures images including said pointer and reflection.

18. The method of claim 14 wherein said imaging devices have fields of view looking across said touch surface and wherein said rows of pixels are horizontal.

19. The method of claim 13 further including the step of providing backlighting for said imaging devices during image capture, said pointer and reflection being represented by non-illuminated pixels in said captured images, empty pixels being illuminated

12. A method of determining pointer contact with a touch surface comprising the steps of:

capturing images looking across said touch surface using a plurality of imaging devices positioned at different locations relative to said touch surface that have overlapping fields of view; and

processing the captured images to detect a pointer and a reflection of the pointer therein and to determine the relative positions of said detected pointer and reflection and thereby determine pointer contact with said touch surface and pointer hover.

20. A touch system comprising:

a touch surface to be contacted by a pointer;

at least one imaging device having a field of view looking generally across said touch surface; and

at least one processor communicating with said at least one imaging device and analyzing images acquired by said at least one imaging device to detect the relative positions of a pointer and a reflection of the pointer therein and thereby determine if a pointer contact with the touch surface has been made.

21. A touch system according to claim 20 wherein said at least one processor analyzes the acquired images to detect a gap between the pointer and its reflection signifying pointer hover relative to said touch surface.

22. A touch system according to claim 21 further including a source of backlighting for said at least one imaging device, said gap between constituted by illuminated pixels separating non-illuminated pixels representing said pointer and reflection.

23. A camera-based touch system comprising:

at least one pair of cameras positioned at spaced locations and having overlapping fields of view encompassing a touch surface on which pointer contacts are made, said cameras looking obliquely across said touch surface and acquiring images; and

a processor receiving and processing image data generated by the cameras to determine the location of a pointer relative to the area when the pointer is captured in images acquired by the cameras and analyzing the image data to detect the relative positions of the pointer and its reflection thereby to determine pointer contact or pointer hover relative to said touch surface.

24. A touch system according to claim 23 wherein said at least one processor analyzes the acquired images to detect a gap between the pointer and its reflection signifying pointer hover relative to said touch surface.

25. A touch system according to claim 24 further including a source of backlighting for said at least one imaging device, said gap between constituted by illuminated pixels separating non-illuminated pixels representing said pointer and reflection.