Optical touch display device, optical touch sensing device and touch sensing method

• US 20100085329A1
• Filed: 07/18/2009
• Published: 04/08/2010
• Est. Priority Date: 10/03/2008
• Status: Abandoned Application

• Current Assignee: National Chiao Tung University (Government of The Republic of China)
• Original Assignee: National Chiao Tung University (Government of The Republic of China)
• Inventors: Tseng, Ping-Chen, Tien, Chung-Hao
• Application Number:
  US12/505,476
• Publication Number:
  US 20100085329A1
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

The present invention provides an optical touch display device, an optical touch sensing device, and a method for calculating a touch position. The optical touch sensing device can be detachably attached on a display panel using adhesive or other method. The present invention includes a first light source, a second light source, a light sensing element, and a processing unit. When an object blocks the path of light, some light sensing elements will receive some or no light. The processing unit will then compute two line segments based on the positions of light sensing elements receiving some or no light. The two line segments cross each other and their intersection is defined as the position of object or the touch position.

Claims

1. An optical touch display device, comprising:

a display panel;

at least a first light source and a second light source disposed close to a periphery of the display panel for substantially simultaneously emitting a light, wherein a traveling direction of the light is substantially parallel to the display panel, the light emitted from the light sources substantially covers the display panel;

at least one light sensing element disposed close to the periphery of the display panel, the light sensing element detects a strength of the light and outputs a sensing signal based on the strength of the light; and

a processing unit electrically coupled to the light sensing element, wherein the processing unit receives the sensing signal and generates a position signal based on the sensing signal.

2. The optical touch display device of claim 1, wherein the display panel includes an element disposition end and a light source end, the light sensing element is disposed at the element disposition end.

3. The optical touch display device of claim 2, wherein the first light source and the second light source are disposed on different parts of the light source end, the first light source and the second light source emit the light substantially toward the element disposition end.

4. The optical touch display device of claim 1, wherein the display panel is rectangular, the first light source and the second light source are respectively disposed on two opposite corners of the display panel.

5. The optical touch display device of claim 4, wherein the light emitted from the first light source travels toward two sides of the display panel next to the second light source, the light emitted from the second light source travels toward two sides of the display panel adjacent to the first light source.

6. The optical touch display device of claim 1, wherein an amplitude of the sensing signal of the light sensing element is directly proportional to the strength of the light, each light sensing element has a corresponding signal level, the processing unit selectively generates the position signal based on a difference between the amplitude of the sensing signal and the signal level of the light sensing element.

7. The optical touch display device of claim 1, wherein the light sensing element has an element position, the first light source and the second light source respectively have a first light source position and a second light source position;

the element position, the first light source position, and the second light source position together form a coordinate system, the element position, the first light source position and the second light source position respectively correspond to coordinates of the coordinate system, the processing unit has a storage section for storing the element position, the first light source position and the second light source position.

8. The optical touch display device of claim 7, wherein an amplitude of the sensing signal is directly proportional to the strength of the light, each light sensing element has a corresponding signal level, the processing unit calculates the position signal based on a difference between the sensing signal and the signal level of the light sensing element to obtain the element position of the light sensing element from the storage section based on the position signal.

9. The optical touch display device of claim 8, wherein the at least one of the light sensing element includes a first light sensing element and a second light sensing element respectively corresponding to the first light source or the second light source, if the sensing signals generated by the first light sensing element and the second light sensing element vary with respect to the corresponding signal level, the processing unit calculates a reference location based on the element positions of the first light sensing element and the second light sensing element, the processing unit then calculates a line segment across the display panel.

10. The optical touch display device of claim 9, wherein the reference location is located between the first light sensing element and the second light sensing element.

11. The optical touch display device of claim 9, wherein when the processing unit has at least two line segments crossing each other, the processing unit outputs the position signal based on an intersection position of the line segments.

12. The optical touch display device of claim 9, wherein when the amplitudes of the sensing signals generated by the light sensing elements vary with respect to the corresponding signal levels, the processing unit calculates the reference location based on two element positions of the light sensing elements.

13. The optical touch display device of claim 1, wherein the first light source is disposed on a side or a corner of the display panel, the second light source is disposed on an opposite side or an opposite corner of the display panel.

14. The optical touch display device of claim 1, further comprising a light diffusion device, wherein the light diffusion device has a light incident surface and a light exit surface, the light emitted from the light sources enters the light incident surface and then exits from the light exit surface according to a diffusion angle.

15. The optical touch display device of claim 1, wherein the light includes a visible light or an invisible light.

16. An optical touch sensing device disposed close to a display panel, the optical touch sensing device comprising:

a frame disposed near an edge of the display panel;

at least a first light source and a second light source disposed close to an edge of the frame for substantially simultaneously emitting a light, wherein a traveling direction of the light substantially parallel to the display panel, the light emitted from the light sources substantially covers the display panel;

at least one light sensing element disposed on the display panel and disposed near an edge of the display panel, the light sensing element detects a strength of the light and outputs a sensing signal based on the strength of the light; and

a processing unit electrically coupled to the light sensing element, wherein the processing unit receives the sensing signal and generates a position signal based on the sensing signal.

17. A method for calculating a touch position on a touch panel, comprising the following steps:

emitting a light toward at least one light sensing element using a first light source and a second light source, wherein the first light source, the second light source, and the light sensing element are disposed close to a periphery of a display panel or an edge of a frame;

comparing a sensing signal generated by each light sensing element with a corresponding signal level of the light sensing element to obtain a first reference position and a second reference position;

calculating a first line segment based on the first reference position and a position of the first light source and calculating a second line segment based on the second reference position and a position of the second light source, wherein the first line segment intersects the second line segment; and

calculating a touch position based on the first line segment and the second line segment.

18. The method of claim 17, wherein the step of obtaining the first reference position and the second reference position further includes the following steps:

comparing the sensing signal generated by each light sensing element with the corresponding signal level of the light sensing element;

classifying the light sensing elements into a first non-illuminated group and a second non-illuminated group based on the comparison result; and

obtaining the first reference position and the second reference position respectively from the light sensing elements in the first non-illuminated group and the second non-illuminated group.

19. The method of claim 17, further comprising a step of generating a position signal based on the touch position.

20. The method of claim 17, further comprising the following steps:

forming a coordinate system, wherein coordinates of the coordinate system respectively correspond to positions of the first light source, the second light source, and the light sensing element; and

storing positions of the first light source, the second light source, and the light sensing element.