Optical touch panel system and positioning method thereof

• US 9,189,106 B2
• Filed: 06/15/2012
• Issued: 11/17/2015
• Est. Priority Date: 09/07/2011
• Status: Active Grant

• Current Assignee: Pixart Imaging Incorporation ROC
• Original Assignee: Pixart Imaging Incorporation ROC
• Inventors: Su, Tzung-Min, Lin, Chih-Hsin, Kao, Ming-Tsan
• Primary Examiner(s): Hicks, Charles
• Assistant Examiner(s): Castiaux, Brent D
• Application Number:
  US13/525,213
• Publication Number:
  US 20130147763A1
• Time in Patent Office: 1,250 Days
• Field of Search: 345173-178, 362600-634
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• 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

Abstract

An optical touch panel system includes: a reflective element disposed on a first side of the touch control area; two lighting elements respectively disposed on a second side and a third side of the touch control area , wherein the second side and the third side are adjacent to each other, and the third side is opposite the first side; a first light projection apparatus including a mirror and a light generator, disposed on the first side and at a location adjacent to a fourth side of the touch control area; an image sensor capturing a first picture and a second picture respectively when the light generator is inactivated and activated; and a processor calculating a coordinate of the object according to geometrical information of an projected object image and a projected mirror image of the object in the first picture and the second picture.

Claims

1. An optical touch panel system for positioning an object in a touch control area, the system comprising:

a reflective element disposed on a first side of the touch control area for reflecting light from the touch control area;

two lighting elements respectively disposed on a second side and a third side of the touch control area, wherein the second side and the third side are adjacent to each other, and the third side is opposite the first side;

a first light projection apparatus including a planar mirror and a light generator, disposed on the first side and at a location adjacent to a fourth side of the touch control area, wherein the planar mirror and the reflective element are adjacent to each other and at a same side of the touch control area;

an image sensor capturing a first picture and a second picture respectively when the light generator is inactivated and activated, the light generator being inactivated and activated when the object is between the first light projection apparatus and the image sensor, wherein when the light generator is inactivated, the planar mirror reflects light external to the first light projection apparatus, and when the light generator is activated, light generated from the light generator goes through the planar mirror, the first light projection apparatus selectively operating to reflect light or to let light pass; and

a processor calculating a coordinate of the object according to optical information of an object and a mirror image of the object in the first picture and the second picture, wherein the optical information of the object is a projected image of the object (projected object image) and the optical information of the mirror image is a projected image of the mirror image (projected mirror image).

2. The optical touch panel system of claim 1, wherein the processor calculates the coordinate of the object according to geometrical information of the optical information, and wherein the geometrical information includes centers, gravity centers, representative positions, or borders of the projected object image and the projected mirror image.

3. The optical touch panel system of claim 1, wherein the first light projection apparatus is adjacent to the fourth side, and the image sensor is disposed at the corner between the third side and the fourth side.

4. The optical touch panel system of claim 1, wherein the first picture includes an overlapped imaging region in which the projected object image overlaps the projected mirror image, or two separate imaging regions one including the projected object image and the other including the projected mirror image;

the second picture includes an imaging region of the projected object image.

5. The optical touch panel system of claim 4, wherein the processor obtains the coordinate of the object according to the border of the overlapped imaging region of the first picture and the gravity center of the imaging region of the second picture.

6. The optical touch panel system of claim 4, wherein the processor obtains the coordinate of the object according to the gravity centers of the two imaging regions of the first picture.

7. The optical touch panel system of claim 1, further comprising a second light projection apparatus disposed on the second side and at a location adjacent to the third side, wherein the second light projection apparatus includes a mirror and a light generator.

8. The optical touch panel system of claim 7, further comprising a lighting element disposed on the fourth side.

9. The optical touch panel system of claim 7, wherein the first picture is captured by the image sensor when the first light projection apparatus inactivates its light generator and the second light projection apparatus activates its light generator, the first picture including one overlapped imaging region in which the projected object image overlaps the projected mirror image, or two separate imaging regions one including the projected object image and the other including the projected mirror image;

the second picture is captured by the image sensor when the first light projection apparatus activates its light generator and the second light projection apparatus inactivates its light generator, wherein the second picture includes two separate imaging regions one including the projected object image and the other including the projected mirror image.

10. The optical touch panel system of claim 7, wherein the length of the first light projection apparatus is smaller than the length of the first side, and the length of the second light projection apparatus is smaller than the length of the second side.

11. The optical touch panel system of claim 9, wherein the processor obtains the coordinate of the object according to the gravity centers of the two imaging regions of the second picture when the first picture includes only one imaging region.

12. The optical touch panel system of claim 9, wherein the processor obtains the coordinate of the object according to the gravity centers of the two imaging regions of the first picture.

13. The optical touch panel system of claim 1, wherein the first light projection apparatus includes a light guide unit, and the planar mirror of the first light projection apparatus is disposed on a side of the light guide unit opposite the touch control area;

when the light generator is activated, the first light projection apparatus serves as a bright light source;

when the light generator is inactivated, light entering the first projection apparatus is reflected by the planar mirror.

14. The optical touch panel system of claim 1, wherein the first projection apparatus includes a light guide unit, and the planar mirror of the first projection apparatus is disposed on a side of the light guide unit opposite the touch control area;

the planar mirror being a transflective lens, and when the light generator is activated, light generated by the light generator passes through the planar mirror so that the first light projection apparatus serves as a bright light source;

when the light generator is inactivated, light entering the first projection apparatus is reflected by the planar mirror.

15. A method of positioning an object in an optical touch panel system, the optical touch panel system including an image sensor for capturing a projected image of an object (projected object image) and a projected image of a mirror image of the object (projected mirror image) in a touch control area, the method comprising:

providing a first light projection apparatus capable of switching between a light emitting mode and a light reflecting mode, the first light projection apparatus switching between the light reflecting mode and the light emitting mode when the object is between the first light projection apparatus and the image sensor, the first light projection apparatus including a planar mirror and a light generator, wherein when the light generator is in the light reflecting mode, the planar mirror reflects light external to the first light projection apparatus, and when the light generator is in the light emitting mode, light generated from the light generator goes through the planar mirror, the first light projection apparatus selectively operating to reflect light or to let light pass;

respectively capturing a first picture and a second picture by the image sensor when the first light projection apparatus is in the light emitting mode and the light reflecting mode, wherein the first picture and the second picture include imaging regions of the projected object image or the projected mirror image;

checking a number of the imaging region or image regions of the first picture;

if the number of the imaging region of the first picture is 1, obtaining the coordinate of the object according to geometrical information of imaging regions in the first picture and the second picture or according to geometrical information of imaging regions in the second picture; and

if the number of the imaging regions of the first picture is 2, obtaining the coordinate of the object according to geometrical information of imaging regions in the first picture;

wherein the planar mirror and a reflective element are disposed at a same side of the touch control area, and have same normal directions, the reflective element reflecting light from the touch control area.

16. The method of positioning an object in an optical touch panel system of claim 15, wherein the geometrical information includes centers, gravity centers, representative positions, or borders of the projected object image and the projected mirror image.

17. The method of positioning an object in an optical touch panel system of claim 15, wherein the imaging region of the first picture has brightness lower than brightness of a rest region of the first picture, and the imaging region of the second picture has brightness lower than brightness of a rest region of the second picture.

18. The method of positioning an object in an optical touch panel system of claim 15, wherein the first picture is captured by the image sensor when the first light projection apparatus inactivates the light generator, the first picture including one overlapped imaging region in which the projected object image overlaps the projected mirror image, or two separate imaging regions one including the projected object image and the other including the projected mirror image;

and wherein the second picture is captured by the image sensor when the first light projection apparatus activates the light generator, the second picture including an imaging region of the projected object image.

19. The method of positioning an object in an optical touch panel system of claim 18, wherein the coordinate of the object is obtained according to the border of the overlapped imaging region of the first picture and the gravity center of the imaging region of the second picture.

20. The method of positioning an object in an optical touch panel system of claim 18, wherein the coordinate of the object is obtained according to the gravity centers of the two imaging regions of the first picture.

21. The method of positioning an object in an optical touch panel system of claim 15, further comprising a step of providing a second light projection apparatus capable of switching between a light emitting mode and a light reflecting mode.

22. The method of positioning an object in an optical touch panel system of claim 21, wherein the first picture is captured by the image sensor when the first light projection apparatus inactivates its light generator and the second light projection apparatus activates its light generator, the first picture including one overlapped imaging region in which the projected object image overlaps the projected mirror image, or two separate imaging regions one including the projected object image and the other including the projected mirror image;

and wherein the second picture is captured by the image sensor when the first light projection apparatus activates its light generator and the second light projection apparatus inactivates its light generator, the second picture including two separate imaging regions of the projected object image and the projected mirror image.

23. The method of positioning an object in an optical touch panel system of claim 22, wherein the coordinate of the object is obtained according to the gravity centers of the two imaging regions of the second picture when the first picture includes only one imaging region.

24. The method of positioning an object in an optical touch panel system of claim 22, wherein the coordinate of the object is obtained according to the gravity centers of the two imaging regions of the first picture.