Optical Position Input System And Method

• US 20120038588A1
• Filed: 08/13/2010
• Published: 02/16/2012
• Est. Priority Date: 08/13/2010
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Liu, Guansong, Wu, Donghui, Shan, Jizhang, Li, Jin
• Granted Patent: US 8,269,750 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• 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

Optical position input systems and methods determine positions of at least one pointing objects within an active touch area. At least three imager modules form images of at least one pointing objects within the active touch area. A processor computes a position of each of the at least one pointing object based upon the images formed by the at least three imager modules.

Claims

1. An optical input system for detecting one or more input positions within an active touch area, comprising:

at least three imager modules peripherally positioned around the active touch area, each imager module capturing images of at least one pointing object within the active touch area; and

a processor for determining each of one or more input positions, relative to the active touch area, based upon the captured images.

2. The system of claim 1, the processor triangulating the one or more input positions based upon images captured by a pair of adjacent image modules, and then determining the one or more input positions as being commonly determined from each pair of adjacent imager modules.

3. The system of claim 1, wherein the active touch area is rectangular and the at least three imager modules are each located proximate to a different one of three corners of the active touch area.

4. The system of claim 1, wherein two adjacent image modules are orthogonal to one another.

5. The system of claim 1, the system further comprising a memory for storing reference images for each of the imager modules, the reference images being subtracted from the captured images to identify position of the at least one pointing object.

6. The system of claim 1, wherein each of the at least three imager modules comprises an image sensor selected from the group including a linear image sensor and a two-dimensional image sensor.

7. The system of claim 1, wherein the at least three imager modules are positioned to provide the most optimum uniformity of position resolution within the active touch area.

8. A method for determining positions of one or more pointing objects within an active touch area, comprising:

simultaneously capturing images of the one or more pointing objects using at least three imager modules peripherally positioned around the active touch area; and

for each pair of images captured from adjacent imager modules;

triangulating potential positions of the one or more pointing objects based upon each pair of images; and

determining the positions of the one or more pointing objects as being common to the potential positions determined from each pair of images.

9. The method of claim 8, further comprising correcting for distortion based upon a calibration process.

10. The method of claim 8, the step of determining the positions comprising:

determining common positions based upon a position resolution of each pair of adjacent imager modules.

11. The method of claim 8, the step of determining the positions comprising:

determining an X coordinate and a Y coordinate of each position for each pair of images at the position;

selecting one of the X-coordinates based upon a highest X-resolution at the position; and

selecting one of the Y-coordinates based upon a highest Y-resolution at the position.

12. The method of claim 8, the step of determining the positions comprising:

determining X and Y coordinates of each position for each pair of adjacent imager modules and selecting one pair of adjacent imager modules based upon an optimal combination of X-resolution and Y-resolution at the position for all pairs of adjacent imager modules.

13. The method of claim 8, the step of determining the positions comprising:

determining X and Y coordinates of each position for each pair of images;

calculating weighted averages of respective X and Y coordinates of each position as final X and Y coordinates, wherein the weight of each X and Y coordinate increases with a respective X-resolution and Y-resolution at the position.

14. The method of claim 8, further comprising:

storing a background image for each of the imager modules;

extracting a differential image between the captured image and the associated background image; and

segmenting the differential image.

15. The method of claim 14, further comprising:

computing and storing a background image texture from each of the stored background images;

computing image texture of the captured images; and

extracting an area having differential texture between the computed image texture of the captured image and the associated background image texture.

16. The method of claim 14, the method further comprising updating the background image if no pointing objects are simultaneously detected by the at least three imager modules.

17. An optical input system for detecting one or more input positions within a rectangular active touch area, comprising:

four imager modules positioned proximate to four corners of the rectangular active touch area, each imager module capturing an image of at least one pointing object within the rectangular active touch area, wherein

a connection between each two adjacent imager modules forms a baseline such that the system comprises four baselines, each of the four baselines being orthogonal to each adjacent baseline and being parallel to the other baseline;

a processor for triangulating the one or more input positions based upon captured images of the at least one pointing object, and determining the one or more input positions as being commonly determined from each pair of adjacent imager modules.

18. The system of claim 17, wherein the processor determines common positions based upon a position resolution of each pair of adjacent imager modules.

19. The system of claim 17, wherein the processor selects the determined positions based upon at least one of the highest X-resolution and the highest Y-resolution among all pairs of adjacent imager modules.

20. The system of claim 17, wherein the determined positions comprise an X coordinate and a Y coordinate, the X coordinate being determined based upon the highest X-resolution for a first pair of adjacent imager modules, and the Y coordinate being determined based upon the highest Y-resolution for a second pair of adjacent imager modules.

21. The system of claim 17, wherein the determined positions comprise an X coordinate and a Y coordinate, the X and Y coordinates being determined based upon an optimum combination of X-resolution and Y-resolution for one pair of adjacent imager modules among all pairs of adjacent imager modules.

22. The method of claim 17, the step of determining the positions comprising:

determining X and Y coordinates of each position for each pair of adjacent imager modules; and

calculating weighted averages of respective X and Y coordinates of each position as final X and Y coordinates, wherein the weight of each X and Y coordinate increases with a respective X-resolution and Y-resolution.

23. A method for determining positions of one or more pointing objects within a rectangular active touch area, comprising:

simultaneously capturing images of the one or more pointing objects using four imager modules peripherally positioned proximate each corner of the rectangular active touch area; and

for each pair of images captured from adjacent imager modules, triangulating potential positions of the one or more pointing objects; and

determining the positions of the one or more pointing objects as being common to the potential positions determined from each pair of images.

24. The method of claim 23, the step of determining the positions comprising determining common positions based upon a position resolution of each pair of adjacent imager modules.

25. The method of claim 23, the step of determining the positions of the one or more pointing objects comprising determining an X coordinate based upon the highest X-resolution at the position for a first pair of the adjacent imager modules and determining a Y coordinate based upon the highest Y-resolution for a second pair of the adjacent imager modules at the position.

26. The method of claim 23, the step of determining the positions of the one or more pointing objects comprising determining X and Y coordinates based upon an optimum combination of X-resolution and Y-resolution at the position within one pair of the adjacent imager modules.

27. The method of claim 23, the step of determining the positions comprising:

determining X and Y coordinates of each position for each pair of images; and

calculating weighted averages of both the X and Y coordinates of each position as final X and Y coordinates, wherein the weight of each X and Y coordinate increases with a respective X-resolution and Y-resolution.