Optical sensing system

• US 8,427,453 B2
• Filed: 04/15/2011
• Issued: 04/23/2013
• Est. Priority Date: 07/10/2008
• Status: Expired due to Fees

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Su, Tzung-Min, Lin, Chih-Hsin, Chen, Hsin-Chia, Lin, Cho-Yi
• Primary Examiner(s): GIESY, ADAM
• Application Number:
  US13/087,392
• Publication Number:
  US 20110193823A1
• Time in Patent Office: 739 Days
• Field of Search: None
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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

An optical sensing system includes a sensing area, a reflective mirror, a first image-sensing device, a second image-sensing device, and a processing circuit. The sensing area is an area in which a plurality of pointing objects may execute touch operation. The reflective mirror generates a mirror image of the sensing area. The first image-sensing device and the second image-sensing device respectively capture images including all or part of the pointing objects in the sensing area, and all or part of the pointing objects in the reflective mirror. The processing circuit generates candidate coordinates according to the images captured by the first and the second image-sensing devices, and obtains the locations of the pointing objects from the candidate coordinates by means of the symmetric relationship between the point objects and the corresponding mirror images with respect to the reflective mirror. In this way, the optical sensing system can perform multi-touch operation.

Claims

1. An optical sensing system, comprising:

a sensing area having a plurality of sides, wherein a plurality of pointing objects execute touch operation within the sensing area;

a reflective mirror generating a mirror image of the sensing area;

a first image-sensing device capturing a first group of real images having all or part of the pointing objects, and a first group of virtual images having all or part of the pointing objects in the reflective mirror;

a second image-sensing device capturing a second group of real images having all or part of the pointing objects, and a second group of virtual images having all or part of the pointing objects in the reflective mirror; and

a processing circuit generating a group of real-image candidate coordinates corresponding to the plurality of pointing objects according to the first group of real images and the second group of real images, and generating a group of virtual-image candidate coordinates corresponding to the plurality of pointing objects according to the first group of virtual images and the second group of virtual images, the processing circuit generating a group of output coordinates corresponding to the plurality of pointing objects according to the group of real-image candidate coordinates and the group of virtual-image candidate coordinates.

2. The optical sensing system of claim 1, wherein the processing circuit determines the first group of real images and the first group of virtual images from images captured by the first image-sensing device according to sequence of the plurality of pointing objects forming images in the images captured by the first image-sensing device, and the processing circuit determines the second group of real images and the second group of virtual images from images captured by the second image-sensing device according to sequence of the plurality of pointing objects forming images in the images captured by the second image-sensing device.

3. The optical sensing system of claim 1, wherein the processing circuit generates a first group of real-image blocking lines according to a location of the first image-sensing device and the first group of real images, and generates a second group of real-image blocking lines according to a location of the second image-sensing device and the second group of real images;

wherein the processing circuit generates a first group of virtual-image blocking lines according to the location of the first image-sensing device and the first group of virtual images, and generates a second group of real-image blocking lines according to the location of the second image-sensing device and the second group of virtual images;

wherein the processing circuit generates the group of real-image candidate coordinates corresponding to the plurality of pointing objects according to crossing points of the first group of real-image blocking lines and the second group of real-image blocking lines, and the processing circuit generates the group of virtual-image candidate coordinates corresponding to the plurality of pointing objects according to crossing points of the first group of virtual-image blocking lines and the second group of virtual-image blocking lines.

4. The optical sensing system of claim 1, wherein the processing circuit detects symmetric relationship between the group of real-image candidate coordinates and the group of virtual-image candidate coordinates with respect to the reflective mirror;

wherein when the processing circuit determines a real-image candidate coordinate of the group of real-image candidate coordinates is symmetrical to a virtual-image candidate coordinate of the group of virtual-image candidate coordinates with respect to the reflective mirror, the processing circuit generates an output coordinate corresponding to a pointing object of the plurality of pointing objects according to the real-image candidate coordinate of the group of real-image candidate coordinates.

5. The optical sensing system of claim 1, further comprising:

a lighting module emitting light to the sensing area;

wherein the lighting module emits infrared light, and both the first image-sensing device and second image-sensing device are infrared light sensing devices.

6. An optical sensing system, comprising:

a sensing area having a plurality of sides, wherein a plurality of pointing objects execute touch operation within the sensing area;

a mirror-surface light-guiding component having a light-emitting surface facing the sensing area, a mirror surface facing the light-emitting surface and generating a mirror image of the sensing area, and a light-receiving surface, the light-emitting surface emitting light to the sensing area when the light-receiving surface receives light;

a light-emitting component emitting light to the light-receiving surface of the mirror-surface light-guiding component in a light-emitting period;

a first image-sensing device capturing a first group of real images having all or part of the pointing objects in the light-emitting period, and capturing the first group of real images and a first group of virtual images having all or part of the pointing objects in the mirror surface in a non-light-emitting period;

a second image-sensing device capturing a second group of real images having all or part of the pointing objects in the light-emitting period, and capturing the second group of real images and a second group of virtual images having all or part of the pointing objects in the mirror surface in the non-light-emitting period; and

a processing circuit generating a group of real-image candidate coordinates corresponding to the plurality of pointing objects according to the first group of real images and the second group of real images, and generating a group of virtual-image candidate coordinates corresponding to the plurality of pointing objects according to the first group of virtual images and the second group of virtual images, the processing circuit generating a group of output coordinates corresponding to the plurality of pointing objects according to the group of real-image candidate coordinates and the group of virtual-image candidate coordinates.

7. The optical sensing system of claim 6, wherein the processing circuit compares the first group of real images captured by the first image-sensing device in the light-emitting period and an image captured by the first image-sensing device in the non-light-emitting period to obtain the first group of virtual images from the image captured by the first image-sensing device in the non-light-emitting period;

wherein the processing circuit compares the second group of real images captured by the second image-sensing device in the light-emitting period and an image captured by the second image-sensing device in the non-light-emitting period to obtain the second group of virtual images from the image captured by the second image-sensing device in the non-light-emitting period.

8. The optical sensing system of claim 6, wherein the processing circuit generates a first group of real-image blocking lines according to a location of the first image-sensing device and the first group of real images, and generates a second group of real-image blocking lines according to a location of the second image-sensing device and the second group of real images;

wherein the processing circuit generates a first group of virtual-image blocking lines according to the location of the first image-sensing device and the first group of virtual images, and generates a second group of real-image blocking lines according to the location of the second image-sensing device and the second group of virtual images;

wherein the processing circuit generates the group of real-image candidate coordinates corresponding to the plurality of pointing objects according to crossing points of the first group of real-image blocking lines and the second group of real-image blocking lines, and the processing circuit generates the group of virtual-image candidate coordinates corresponding to the plurality of pointing objects according to crossing points of the first group of virtual-image blocking lines and the second group of virtual-image blocking lines.

9. The optical sensing system of claim 6, wherein the processing circuit detects symmetric relationship between the group of real-image candidate coordinates and the group of virtual-image candidate coordinates with respect to the reflective mirror;

wherein when the processing circuit determines a real-image candidate coordinate of the group of real-image candidate coordinates is symmetrical to a virtual-image candidate coordinate of the group of virtual-image candidate coordinates with respect to the reflective mirror, the processing circuit generates an output coordinate corresponding to a pointing object of the plurality of pointing objects according to the real-image candidate coordinate of the group of real-image candidate coordinates.

10. The optical sensing system of claim 6, further comprising:

a lighting module emitting light to the sensing area;

wherein the lighting module emits infrared light, and both the first image-sensing device and second image-sensing device are infrared light sensing devices.

11. An optical sensing system, comprising:

a sensing area having a plurality of sides, wherein a plurality of pointing objects execute touch operation within the sensing area;

a reflective mirror generating a mirror image of the sensing area;

a first image-sensing device capturing a first image having all or part of the pointing objects, and a first group of virtual images having all or part of the pointing objects in the reflective mirror;

a second image-sensing device capturing a second image having all or part of the pointing objects and a second group of virtual images having all or part of the pointing objects in the reflective mirror; and

a processing circuit generating a first group of blocking lines according to the first image and a location of the first image-sensing device, and generating a second group of blocking lines according to the second image and a location of the second image-sensing device, the processing circuit generating a group of candidate coordinates corresponding to the plurality of pointing objects according to the first group of blocking lines and the second group of blocking lines, and generating a group of output coordinates corresponding to the plurality of pointing objects according to the group of candidate coordinates and a location of the reflective mirror.

12. The optical sensing system of claim 11, wherein the processing circuit generates a group of real-image candidate coordinates in the sensing area and a group of virtual-image candidate coordinates in the mirror image generated by the reflective mirror according to the group of candidate coordinates corresponding to the plurality of pointing objects and the location of the reflective mirror.

13. The optical sensing system of claim 12, wherein the processing circuit detects symmetric relationship between the group of real-image candidate coordinates and the group of virtual-image candidate coordinates with respect to the reflective mirror;

wherein when the processing circuit determines a real-image candidate coordinate of the group of real-image candidate coordinates is symmetrical to a virtual-image candidate coordinate of the group of virtual-image candidate coordinates with respect to the reflective mirror, the processing circuit generates an output coordinate corresponding to a pointing object of the plurality of pointing objects according to the real-image candidate coordinate of the group of real-image candidate coordinates.

14. The optical sensing system of claim 13, the processing circuit calculates a virtual-image distance between the virtual candidate coordinate of the group of virtual candidate coordinates and the reflective mirror, and generates a candidate line connected between the real-image candidate coordinate of the group of real-image candidate coordinates and the virtual-image candidate coordinate of the group of virtual-image candidate coordinates;

wherein when length of the candidate line is substantially twice that of the virtual-image distance, and the candidate line is perpendicular to the reflective mirror, the processing circuit determines the real-image candidate coordinate of the group of real-image candidate coordinates is symmetrical to the virtual-image candidate coordinate of the group of virtual-image candidate coordinates with respect to the reflective mirror.

15. The optical sensing system of claim 11, wherein the processing circuit generates a first group of mirror-image lines according to the first group of blocking lines and a location of a mirror image of the first image-sensing device, and generates a second group of mirror-image lines according to the second group of blocking lines and a location of a mirror image of the second image-sensing device;

wherein the processing circuit generates a group of first candidate coordinates in the sensing area according to the first group of blocking lines and the second group of blocking lines, and generates a group of second candidate coordinates in the sensing area according to the first group of mirror-image lines and the second group of mirror-image lines;

wherein the processing circuit generates the group of output coordinates corresponding to the plurality of pointing objects according to the group of first candidate coordinates and the group of second candidate coordinates.

16. The optical sensing system of claim 15, wherein the processing circuit calculates a candidate distance between a first candidate coordinate of the group of first candidate coordinates and a second candidate coordinate of the group of second candidate coordinates;

wherein when the candidate distance is shorter than an error distance, the processing circuit generates an output coordinate corresponding to a pointing object of the plurality of pointing objects according to the first candidate coordinate of the group of first candidate coordinates and the second candidate coordinate of the group of second candidate coordinates.

17. The optical sensing system of claim 11, further comprising:

a lighting module emitting light to the sensing area;

wherein the lighting module emits infrared light, and both the first image-sensing device and second image-sensing device are infrared light sensing devices.

18. An optical sensing system, comprising:

a sensing area having a plurality of sides, wherein a plurality of pointing objects execute touch operation within the sensing area;

a reflective mirror generating a mirror image of the sensing area;

a first image-sensing device capturing a first group of real images having all or part of the pointing objects, and a first group of virtual images having all or part of the pointing objects in the reflective mirror;

a second image-sensing device capturing a second group of real images having all or part of the pointing objects, and a second group of virtual images having all or part of the pointing objects in the reflective mirror; and

a processing circuit generating a group of first candidate coordinates corresponding to the plurality of pointing objects according to the first group of real images and the first group of virtual images, and generating a group of second candidate coordinates corresponding to the plurality of pointing objects according to the second group of real images and the second group of virtual images, the processing circuit generating a group of output coordinates corresponding to the plurality of pointing objects according to the group of first candidate coordinates and the group of second candidate coordinates.

19. The optical sensing system of claim 18, wherein the processing circuit determines the first group of real images and the first group of virtual images in images captured by the first image-sensing device according to sequence of the pointing objects forming images in the images captured by the first image-sensing device, and the processing circuit determines the second group of real images and the second group of virtual images from images captured by the second image-sensing device according to sequence of the pointing objects forming images in the images captured by the second image-sensing device.

20. The optical sensing system of claim 18, wherein the reflective mirror is a mirror-surface light-guiding component having a light-emitting surface facing the sensing area, a mirror surface facing the light-emitting surface and generating a mirror image of the sensing area, and a light-receiving surface, wherein the light-emitting surface emits light to the sensing area when the light-receiving surface receives light;

wherein the optical sensing system further comprises;

a light-emitting component emitting light to the light-receiving surface of the mirror-surface light-guiding component in a light-emitting period;

wherein the first image-sensing device captures the first group of real images in the light-emitting period, and captures the first group of real images and the first group of virtual images in a non-light-emitting period;

wherein the second image-sensing device captures the second group of real images in the light-emitting period, and captures the second group of real images and the second group of virtual images in the non-light-emitting period;

wherein the processing circuit compares the first group of real images captured by the first image-sensing device in the light-emitting period and an image captured by the first image-sensing device in the non-light-emitting period to obtain the first group of virtual images from the image captured by the first image-sensing device in the non-light-emitting period;

wherein the processing circuit compares the second group of real images captured by the second image-sensing device in the light-emitting period and an image captured by the second image-sensing device in the non-light-emitting period to obtain the second group of virtual images from the image captured by the second image-sensing device in the non-light-emitting period.

21. The optical sensing system of claim 18, wherein the processing circuit generates a first group of real-image blocking lines according to a location of the first image-sensing device and the first group of real images, and generates a first group of virtual-image blocking lines according to the location of the first image-sensing device and the first group of virtual images;

wherein the processing circuit generates a first group of mirror-image lines symmetrical to the first group of virtual-image blocking lines with respect to the reflective mirror according to the first group of virtual-image blocking lines and a location of a mirror image of the first image-sensing device;

wherein the processing circuit generates the group of first candidate coordinates according to the first group of real-image blocking lines and the first group of mirror-image lines;

wherein the processing circuit generates a second group of real-image blocking lines according to a location of the second image-sensing device and the second group of real images, and generates a second group of virtual-image blocking lines according to the location of the second image-sensing device and the second group of virtual images;

wherein the processing circuit generates a second group of mirror-image lines symmetrical to the second group of virtual-image blocking lines with respect to the reflective mirror according to the second group of virtual-image blocking lines and a location of a mirror image of the second image-sensing device;

wherein the processing circuit generates the group of the second candidate coordinates according to the second group of real-image blocking lines and the second group of mirror-image lines.

22. The optical sensing system of claim 21, wherein the processing circuit generates the group of output coordinates corresponding to the plurality of pointing objects according to coordinates included in an intersection of the group of the first candidate coordinates and the group of the second candidate coordinates.

23. The optical sensing system of claim 21, wherein the processing circuit calculates a candidate distance between a first candidate coordinate of the group of first candidate coordinates and a second candidate coordinate of the group of second candidate coordinates;

wherein when the candidate distance is shorter than an error distance, the processing circuit generates an output coordinate corresponding to a pointing object of the plurality of pointing objects according to the first candidate coordinate of the group of first candidate coordinates and the second candidate coordinate of the group of second candidate coordinates.

24. The optical sensing system of claim 18, further comprising:

a lighting module emitting light to the sensing area;

wherein the lighting module emits infrared light, and both the first image-sensing device and second image-sensing device are infrared light sensing devices.