Method of detecting touch position, touch position detecting apparatus for performing the method and display apparatus having the touch position detecting apparatus

• US 8,633,918 B2
• Filed: 12/17/2010
• Issued: 01/21/2014
• Est. Priority Date: 03/09/2010
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Jin-Hwan, Cho, Hyun-Min, Kim, Guk-Hyun, Kim, Jong-Hee, Cho, Hyun-Jin
• Primary Examiner(s): NGUYEN, KIMNHUNG T
• Application Number:
  US12/971,251
• Publication Number:
  US 20110221997A1
• Time in Patent Office: 1,131 Days
• Field of Search: 345173-179, 359/487, 359/529, 359/652, 178 1801- 1804
• US Class Current: 345/176
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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

A light waveguide has a rectangular plate shape and is configured to totally reflect internal light arriving at an angle greater than a critical angle. Light emitting parts are disposed at corners of the light waveguide. Each of the light emitting parts emits light once in a period. A first light receiving part is disposed along a first side surface of the light waveguide, and receives light emitted from the light emitting parts adjacent to a second side surface facing the first side surface of the light waveguide. The second light receiving part is disposed along the second side surface of the light waveguide, and receives light emitted from the light emitting parts adjacent to the first side surface. A detecting part detects a touch position based on an amount of the light received by the first and second light receiving parts.

Claims

1. A method of detecting a touch position on a touch-sensitive panel, the method comprising:

emitting light from each of a plurality of light emitting parts respectively disposed exclusively at four corners of a light waveguide having a rectangular plate shape, wherein each of the plurality of light emitting parts emits light once in a period;

receiving a quantity of light by light receiving parts disposed along first and second side surfaces of the light waveguide, the second side surface facing the first side surface, wherein the quantity of light received depends upon the presence of a touch; and

detecting a position of the touch based on the quantity of the light received in the light receiving parts.

2. The method of claim 1, wherein the light receiving part disposed along the first side surface of the light waveguide receives the light emitted from the light emitting parts adjacent to the second side surface of the light waveguide, and the light receiving part disposed along the second side surface of the light waveguide receives the light emitted from the light emitting parts adjacent to the first side surface of the light waveguide.

3. The method of claim 1, wherein the light emitting parts are driven to emit light in sequence.

4. A method of detecting a touch position on a touch-sensitive panel, the method comprising:

emitting light from each of a plurality of light emitting parts respectively disposed at corners of a light waveguide having a rectangular plate shape, wherein each of the plurality of light emitting parts emits light once in a period;

receiving a quantity of light by light receiving parts disposed along first and second side surfaces of the light waveguide, the second side surface facing the first side surface, wherein the quantity of light received depends upon the presence of a touch; and

detecting a position of the touch based on the quantity of the light received in the light receiving parts, wherein detecting the touch position comprises;

obtaining 2N coordinates from the quantity of the received light within a coordinate system having a first axis substantially parallel with a longitudinal side of the first side surface of the light waveguide and a second axis substantially parallel with a longitudinal side of a third side surface of the light waveguide, the third side surface being substantially perpendicular to the first side surface; and

calculating the 2N coordinates to detect N touch positions, wherein N is a positive integer.

5. The method of claim 4, wherein detecting the touch position further comprises detecting the touch position using a position which is symmetric to the touch position with respect to a center of the light waveguide.

6. The method of claim 4, wherein coordinates having the smallest quantity of the received light in each light receiving range are obtained when the 2N coordinates are obtained from the quantity of the received light.

7. The method of claim 4, wherein detecting the touch position further comprises:

matching the 2N coordinates based on light modulating intensity widths respectively corresponding to the 2N coordinates when N is greater than or equal to 2.

8. The method of claim 7, wherein matching the 2N coordinates comprises:

converting the light modulating intensity widths respectively corresponding to the 2N coordinates into digital values;

arranging the 2N coordinates according to light receiving time of the light receiving parts and sizes of the light modulating intensity widths which are converted into the digital values; and

cross-matching the arranged 2N coordinates to output N coordinates.

9. A touch position detecting apparatus comprising:

a light waveguide having a rectangular plate shape and having an index of refraction greater than an index of refraction of air;

a plurality of light emitting parts respectively disposed exclusively at four corners of the light waveguide, wherein each of the plurality of light emitting parts emits light once in a period;

a first light receiving part disposed along a first side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to a second side surface of the light waveguide wherein the quantity of light received depends upon the presence of a touch, the second side surface facing the first side surface;

a second light receiving part disposed along the second side surface of the light waveguide, and receiving a quantity light emitted from the light emitting parts adjacent to the first side surface of the light waveguide, wherein the quantity of light received depends upon the presence of a touch; and

a detecting part detecting a position of the touch based on the quantity of the light received by the first and second light receiving parts.

10. The touch position detecting apparatus of claim 9, wherein the light emitting parts are driven to emit light in sequence.

11. The touch position detecting apparatus of claim 9, wherein the corners of the light waveguide are chamfered to create the light emitting parts.

12. The touch position detecting apparatus of claim 9, wherein each of the light emitting parts comprises an infrared light emitting diode (LED).

13. A touch position detecting apparatus comprising:

a light waveguide having a rectangular plate shape and having an index of refraction greater than an index of refraction of air;

a plurality of light emitting parts respectively disposed at corners of the light waveguide, wherein each of the plurality of light emitting parts emits light once in a period;

a first light receiving part disposed along a first side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to a second side surface of the light waveguide wherein the quantity of light received depends upon the presence of a touch, the second side surface facing the first side surface;

a second light receiving part disposed along the second side surface of the light waveguide, and receiving a quantity light emitted from the light emitting parts adjacent to the first side surface of the light waveguide, wherein the quantity of light received depends upon the presence of a touch; and

a detecting part detecting a position of the touch based on the quantity of the light received by the first and second light receiving parts, wherein the detecting part comprises;

an obtaining part obtaining 2N coordinates from the quantity of the received light, within a coordinate system having a first axis substantially parallel with a longitudinal side of the first side surface of the light waveguide and a second axis substantially parallel with a longitudinal side of a third side surface of the light waveguide, the third side surface being substantially perpendicular to the first side surface; and

a calculating part calculating the 2N coordinates to detect N touch positions, wherein N is a positive integer.

14. The touch position detecting apparatus of claim 13, wherein each of the 2N coordinates is coordinates having the smallest quantity of the received light in each light receiving range.

15. The touch position detecting apparatus of claim 13, wherein the detecting part further comprises a matching part matching the 2N coordinates based on light modulating intensity widths respectively corresponding to the 2N coordinates when N is greater than or equal to 2.

16. The touch position detecting apparatus of claim 15, wherein the matching part comprises:

a converting part converting the light modulating intensity widths respectively corresponding to the 2N coordinates into digital values;

an arranging part arranging the 2N coordinates according to light receiving time of the light receiving parts and sizes of the light modulating intensity widths which are converted into the digital values; and

an outputting part cross-matching the arranged 2N coordinates to output N coordinates.

17. A display apparatus comprising:

a light waveguide having a rectangular plate shape and having an index of refraction greater than an index of refraction of air;

a plurality of light emitting parts respectively disposed exclusively at four corners of the light waveguide, wherein each of the plurality of light emitting parts emits light once in a period;

a first light receiving part disposed along a first side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to a second side surface of the light waveguide wherein the quantity of light received depends upon the presence of a touch, the second side surface facing the first side surface;

a second light receiving part disposed along the second side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to the first side surface of the light waveguide, wherein the quantity of light received depends upon the presence of a touch;

a detecting part detecting a position of the touch based on the quantity of light received by the first and second light receiving parts;

a thin-film transistor (TFT) substrate disposed under the light waveguide to receive an image signal according to the touch position; and

a liquid crystal layer formed between the light waveguide and the TFT substrate.

18. The display apparatus of claim 17, wherein the corners of the light waveguide are chamfered to create the light emitting parts.

19. A display apparatus comprising:

a light waveguide having a rectangular plate shape and having an index of refraction greater than an index of refraction of air;

a plurality of light emitting parts respectively disposed at corners of the light waveguide, wherein each of the plurality of light emitting parts emits light once in a period;

a first light receiving part disposed along a first side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to a second side surface of the light waveguide wherein the quantity of light received depends upon the presence of a touch, the second side surface facing the first side surface;

a second light receiving part disposed along the second side surface of the light waveguide, and receiving quantity of light emitted from the light emitting parts adjacent to the first side surface of the light waveguide, wherein the quantity of light received depends upon the presence of a touch;

a detecting part detecting a position of the touch based on the quantity of light received by the first and second light receiving parts;

a thin-film transistor (TFT) substrate disposed under the light waveguide to receive an image signal according to the touch position;

a liquid crystal layer formed between the light waveguide and the TFT substrate,

a color filter disposed over the TFT substrate;

a low refraction layer disposed between the liquid crystal layer and a first surface of the light waveguide; and

a polarizing plate disposed on a second surface of the light waveguide facing the first substrate.

20. A display apparatus comprising:

a light waveguide having a rectangular plate shape and having an index of refraction greater than an index of refraction of air;

a plurality of light emitting parts respectively disposed at corners of the light waveguide, wherein each of the plurality of light emitting parts emits light once in a period;

a first light receiving part disposed along a first side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to a second side surface of the light waveguide wherein the quantity of light received depends upon the presence of a touch, the second side surface facing the first side surface;

a second light receiving part disposed along the second side surface of the light waveguide, and receiving a quantity of light emitted from the light emitting parts adjacent to the first side surface of the light waveguide, wherein the quantity of light received depends upon the presence of a touch;

a detecting part detecting a position of the touch based on the quantity of light received by the first and second light receiving parts;

a thin-film transistor (TFT) substrate disposed under the light waveguide to receive an image signal according to the touch position;

a liquid crystal layer formed between the light waveguide and the TFT substrate,

a color filter substrate disposed between the light waveguide and the liquid crystal layer; and

a polarizing plat disposed between the light waveguide and the color filter substrate.