Optical touch panels and methods of driving the same

• US 20110141060A1
• Filed: 08/17/2010
• Published: 06/16/2011
• Est. Priority Date: 12/10/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sun-il, Song, I-hun, Park, Jae-chul, Kim, Chang-jung, Jeon, Sang-hun
• Granted Patent: US 8,917,260 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0386 for light pen
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

An optical touch panel may include a plurality of light-sensing areas. The plurality of light-sensing areas may be integrally formed with pixels in a display panel or may be formed on the display panel, in order to sense incident light from outside the optical touch panel. A method of driving an optical touch panel may include sensing a change in an output from a plurality of light-sensing areas between two time points and determining that there is an optical input when the change in the output is greater than or equal to a first reference value that is defined in advance. The light-sensing areas may be integrally formed with pixels in a display panel or formed on a surface of the display panel, for sensing incident light from outside the optical touch panel.

Claims

1. An optical touch panel, comprising:

a plurality of light-sensing areas;

wherein the plurality of light-sensing areas are integrally formed with pixels in a display panel or formed on the display panel, in order to sense incident light from outside the optical touch panel.

2. The optical touch panel of claim 1, wherein a plurality of pixels adapted to form images and the plurality of light-sensing areas, disposed on sides of the plurality of pixels at a same layer as that of the pixels, are disposed in the display panel.

3. The optical touch panel of claim 1, wherein a red sub-pixel adapted to emit red light, a green sub-pixel adapted to emit green light, and a blue sub-pixel adapted to emit blue light are associated with each of the light-sensing areas.

4. The optical touch panel of claim 1, wherein the light-sensing areas are integrally fabricated with the display panel on a surface of the display panel, or are fabricated separately from the display panel and attached on a surface of the display panel.

5. The optical touch panel of claim 1, wherein the plurality of light-sensing areas are disposed only on a part of the display panel.

6. The optical touch panel of claim 1, wherein a light-sensitive transparent oxide transistor is used as a light sensor in each of the light-sensing areas.

7. The optical touch panel of claim 6, wherein the light-sensitive transparent oxide transistor comprises:

a gate electrode on a substrate;

a gate insulating layer covering the substrate and the gate electrode;

a light-sensitive transparent oxide semiconductor layer partially covering the gate insulating layer; and

a source electrode and a drain electrode on opposite sides of the light-sensitive transparent oxide semiconductor layer.

8. The optical touch panel of claim 7, wherein the light-sensitive transparent oxide semiconductor layer uses a zinc oxide (ZnO)-based oxide semiconductor or an oxide semiconductor in which one or more of indium (In), gallium (Ga), and hafnium (Hf) is mixed in the ZnO.

9. The optical touch panel of claim 1, further comprising:

an image sensor controller adapted to read signals from the light-sensing areas;

a row decoder adapted to provide the light-sensing areas with reading control signals according to control of the image sensor controller; and

an analog/digital (A/D) converter adapted to receive a light intensity signal from the light-sensing areas and adapted to convert the light intensity signal to a digital signal.

10. The optical touch panel of claim 9, wherein the A/D converter comprises a correlated double sampling (CDS) circuit adapted to remove noise included in the light intensity signal from the light-sensing areas.

11. The optical touch panel of claim 9, wherein the image sensor controller senses a change in an output from a specific light-sensing area between two time points, and determines that there is an optical input to the optical touch panel when the change in the output according to time is greater than or equal to a first reference value that is defined in advance.

12. The optical touch panel of claim 9, wherein the image sensor controller compares information on predicted light intensity of an image displayed on at least one pixel around a corresponding light-sensing area with information on light intensity measured in the corresponding light-sensing area, and determines that there is an optical input to the optical touch panel when the measured light intensity is greater than the predicted light intensity by a second reference value that is defined in advance.

13. The optical touch panel of claim 12, wherein the information on predicted light intensity of the image displayed on the at least one pixel around the corresponding light-sensing area is provided from a display controller that controls the display panel.

14. The optical touch panel of claim 9, wherein the image sensor controller senses a change in an output from a specific light-sensing area between two time points, and wherein the image sensor controller determines that there is an optical input to the optical touch panel when the change in the output according to time is greater than or equal to a first reference value that is defined in advance or a measured light intensity is greater than a predicted light intensity by a second reference value that is defined in advance.

15. The optical touch panel of claim 11, wherein the image sensor controller generates a selection signal when the optical input is maintained in the specific light-sensing area for a reference time.

16. The optical touch panel of claim 11, wherein the image sensor controller generates a selection signal when a measured light intensity, after the optical input is generated, is changed in a reference range.

17. The optical touch panel of claim 11, wherein the image sensor controller senses variation in location of the specific light-sensing area in which the optical input is incident, and generates a selection signal when the location of the specific light-sensing area is changed in a pattern.

18. The optical touch panel of claim 9, wherein the image sensor controller comprises:

a control unit adapted to calculate location information of the light-sensing areas and intensity information in the light-sensing areas;

a time variation determiner adapted to determine whether a change in an output from the light sensing areas according to time is greater than or equal to a first reference value;

an input/output variation determiner adapted to determine whether light intensity measured in the light-sensing areas is greater than a predicted light intensity by a second reference value;

a logic sum circuit adapted to calculate a logic sum of an output from the time variation determiner and an output from the input/output variation determiner; and

a weight logic circuit adapted to count a time of maintaining an optical input to the optical touch panel.

19. A method of driving an optical touch panel, the method comprising:

sensing a change in an output from a plurality of light-sensing areas between two time points; and

determining that there is an optical input when the change in the output is greater than or equal to a first reference value that is defined in advance;

wherein the light-sensing areas are integrally formed with pixels in a display panel or formed on a surface of the display panel, for sensing incident light from outside the optical touch panel.

20. The method of claim 19, further comprising:

comparing information on predicted light intensity of an image displayed on at least one pixel around a corresponding light-sensing area with information on light intensity measured in the corresponding light-sensing area; and

determining that there is an optical input to the optical touch panel when the measured light intensity is greater than the predicted light intensity by a second reference value that is defined in advance.

21. The method of claim 20, wherein the information on predicted light intensity of the image displayed on the at least one pixel around the corresponding light-sensing area is provided from a display controller for controlling the display panel.

22. The method of claim 20, wherein when the change in the output according to time is greater than or equal to the first reference value that is defined in advance or the measured light intensity is greater than the predicted light intensity by the second reference value that is defined in advance, it is determined that there is the optical input to the optical touch panel.

23. The method of claim 19, further comprising:

generating a selection signal when the optical input to a specific light-sensing area is maintained for a reference time.

24. The method of claim 19, further comprising:

generating a selection signal when a measured light intensity, after the optical input is generated, is changed in a reference range.

25. The method of claim 19, further comprising:

generating a selection signal when variation in location of a specific light-sensing area in which the optical input is incident is sensed and the location of the specific light-sensing area is changed in a pattern.