Apparatus for determining the location of a pointer within a region of interest

• US 8,456,418 B2
• Filed: 06/13/2007
• Issued: 06/04/2013
• Est. Priority Date: 10/09/2003
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ung, Chi Man Charles, Booth, David Kenneth, Worthington, Stephen, Fletcher, Mark Andrew, Sirotich, Roberto A. L.
• Primary Examiner(s): Amadiz, Rodney
• Application Number:
  US11/762,198
• Publication Number:
  US 20070236454A1
• Time in Patent Office: 2,183 Days
• Field of Search: 178 1801- 1803, 178/18.09, 178/18.11, 250/221, 341/31, 345/173, 345/175, 345/178, 345156-158, 356620-623
• US Class Current: 345/158
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

An apparatus for detecting a pointer within a region of interest includes a first reflective element extending along a first side of the region of interest and reflecting light towards the region of interest. A second reflective element extends along a second side of the region of interest and reflects light towards the region of interest. The second side is joined to the first side to define a first corner. A non-reflective region generally in the plane of at least one of the first and second reflective elements is adjacent the first corner. At least one imaging device captures images of the region of interest including reflections from the first and second reflective elements.

Claims

1. An apparatus for detecting a pointer within a region of interest comprising:

a generally rectangular touch surface having an active sub-area defining said region of interest;

a detecting device entirely spaced from said sub-area by a first margin and looking across said sub-area from one corner of said touch surface;

at least one illumination source adjacent said detecting device and directing light at least across said region of interest; and

a reflective element extending along one side of said touch surface and reflecting light towards said region of interest and towards said detecting device, said reflective element being spaced from said sub-area by a second margin, wherein when a pointer is positioned within said region of interest, said detecting device sees said pointer and a reflection of said pointer appearing in said reflective element, each margin being calculated such that the dimensions of the margins inhibit said detecting device from seeing a pointer within said region of interest that merges with said reflection to an extent that said pointer and reflection cannot be resolved.

2. An apparatus according to claim 1 wherein said detecting device includes an image sensor having an active pixel sub-array, light reflected by said reflective element being directed towards said active pixel sub-array.

3. An apparatus according to claim 2 wherein said reflective element is angled relative to said touch surface to aim reflected light towards said pixel sub-array.

4. An apparatus according to claim 1 further comprising non-reflective material extending along the other sides of said touch surface and facing said detecting device.

5. An apparatus according to claim 4 wherein said active sub-area is delineated by an L-shaped margin about said touch surface, said L-shaped margin having one arm extending along one side of said touch surface generally the length of said reflective element and a second arm extending along another side of said touch surface generally from said reflective surface to said detecting device.

6. An apparatus according to claim 4 wherein said detecting device calculates the location of said pointer within said region of interest via triangulation based on the pointer image and pointer reflection.

7. An apparatus according to claim 1 wherein said detecting device calculates the location of said pointer within said region of interest via triangulation based on the pointer image and pointer reflection.

8. An apparatus for detecting a pointer within a region of interest comprising:

a reflective element extending along a first side of said region of interest and reflecting light towards said region of interest;

non-reflective surfaces extending along the other sides of said region of interest; and

at least one imaging device capturing images of said region of interest including reflections from said reflective element, said at least one imaging device having an active pixel sub-array and said reflective element being configured to aim reflected light towards said active pixel sub-array, wherein said region of interest and said reflective element are separated by a first margin, wherein said region of interest and the non-reflective surface that extends from the reflective element to the at least one imaging device are separated by a second margin and wherein said at least one imaging device is spaced from said region of interest, said margins and spacing between the at least one imaging device and region of interest being calculated so that the dimensions thereof inhibit merging of pointers and pointer reflections in captured images.

9. An apparatus according to claim 8 wherein said at least one imaging device comprises an image sensor having an active pixel sub-array, light reflected by said reflective element being directed towards said active pixel sub-array.

10. An apparatus according to claim 9 wherein said reflective element is angled relative to said region of interest to aim reflected light towards said pixel sub-array.

11. An apparatus according to claim 8 wherein said at least one imaging device is a single imaging device adjacent a corner of said region of interest.

12. An apparatus according to claim 11 further comprising at least one illumination source adjacent said at least one imaging device, said illumination source directing light across said region of interest.

13. An apparatus according to claim 12 wherein said at least one imaging device includes an image sensor having an active pixel sub-array, light reflected by said reflective element being directed towards said active pixel sub-array.

14. An apparatus according to claim 13 wherein said reflective element is angled relative to said region of interest to aim reflected light towards said pixel sub-array.

15. An apparatus for detecting a pointer within a generally rectangular region of interest comprising:

a detecting device looking across said region of interest from one corner thereof, said detecting device being spaced from said region of interest;

a reflective surface extending along one side of said region of interest that is within the field of view of said detecting device and reflecting light towards said region of interest;

non-reflecting surfaces extending along the remaining sides of said region of interest; and

at least one illumination source providing backlight illumination across said region of interest, wherein said region of interest and said reflective surface are separated by a first margin, wherein said region of interest and the non-reflective surface that extends from the reflective surface to the detecting device are separated by a second margin and wherein when a pointer is positioned within said region of interest, said detecting device sees said pointer directly and a reflection of said pointer in said reflective surface, said margins and spacing between the detecting device and region of interest being calculated so that the dimensions thereof inhibit merging of pointers and pointer reflections in image frames captured by said detecting device.

16. An apparatus according to claim 15 wherein said detecting device calculates the location of said pointer within said region of interest via triangulation based on the pointer image and pointer reflection.

17. An apparatus according to claim 16 including a single illumination source disposed adjacent said one corner.

18. An apparatus according to claim 17 wherein said detecting device includes an image sensor having an active pixel sub-array, light reflected by said reflective surface being directed towards said active pixel sub-array.

19. An apparatus according to claim 18 wherein said reflective surface is angled relative to said region of interest to aim reflected light towards said pixel sub-array.