Photosensor, display device including the same, and driving method thereof

• US 9,142,704 B2
• Filed: 07/03/2012
• Issued: 09/22/2015
• Est. Priority Date: 03/23/2012
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Jung, Suk Won, Seo, Seung Mi, Yang, Sung Hoon
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): Shen, Yuzhen
• Application Number:
  US13/540,677
• Publication Number:
  US 20130249817A1
• Time in Patent Office: 1,176 Days
• Field of Search: 345/173, 345/175, 345/207
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: H01L 31/167 the light sources and the devices sensitive to radiation all being semiconductor devices characterised by potential barriers

Abstract

A photosensor includes a sensing switching element, a sensing element, and a reset switching element. The sensing switching element includes an output terminal connected to a sensing signal line, a control terminal connected to a first gate line, and an input terminal connected to the first node. The sensing element includes an output terminal connected to a first node, a control terminal connected a second gate line disposed next to the first gate line, and an input terminal connected to a source voltage line transmitting a source voltage. The sensing element senses light. The reset switching element includes an output terminal connected to the first node, a control terminal connected to the second gate line, and an input terminal connected to a driving voltage line transmitting a driving voltage.

Claims

1. A photosensor comprising:

a sensing switching element including an output terminal connected to a sensing signal line, a control terminal connected to a first gate line, and an input terminal continuously and directly connected to a first node;

a sensing element including an output terminal connected to the first node, a control terminal connected to a second gate line, and an input terminal connected to a source voltage line transmitting a source voltage, the sensing element configured to sense light; and

a reset switching element including an output terminal connected to the first node, a control terminal connected to the same second gate line, and an input terminal connected to a driving voltage line transmitting a driving voltage.

2. The photosensor of claim 1, wherein the photosensor is configured such that the voltage of the first node corresponds to Vd−

(Rr*((Vd−

Vs)/(Rr+Rp))), where Vd represents the driving voltage, Vs represents the source voltage, Rr represents a resistance of the reset switching element turned on, and Rp represents a resistance of the sensing element turned on.

3. The photosensor of claim 1, wherein the sensing element senses light when the first gate line and the second gate line are supplied with a gate-off voltage, and a sensing signal is output to the sensing signal line according to the voltage of the first node when the first gate line is supplied with a gate-on voltage, after the sensing element senses the light.

4. The photosensor of claim 1, wherein the sensing element is turned on when the second gate line is supplied with the gate-on voltage.

5. The photosensor of claim 1, wherein the control terminal of the sensing element comprises:

a light blocking film positioned on an insulation substrate;

a lower gate electrode connected to the light blocking film; and

an upper gate electrode facing the lower gate electrode with respect to the output terminal and the input terminal of the sensing element.

6. The photosensor of claim 5, wherein the light blocking film transmits light having a wavelength band sensed by the sensing element and blocks light outside of the wavelength band.

7. The photosensor of claim 5, wherein the source voltage line is positioned in a same layer as the upper gate electrode, and the sensing signal line and the driving voltage line are positioned in a same layer.

8. A display device comprising:

a sensing switching element including an output terminal connected to a sensing signal line, a control terminal connected to a first gate line, and an input terminal directly connected to a first node;

a sensing capacitor connected to the first node;

a sensing element including an output terminal connected to the first node, a control terminal connected to a second gate line disposed next to the first gate line, and an input terminal connected to a source voltage line transmitting a source voltage, the sensing element configured to sense light; and

a reset switching element including an output terminal connected to the first node, a control terminal connected to the same second gate line, and an input terminal connected to a driving voltage line transmitting a driving voltage,

wherein the driving voltage line is a line different from the first gate line.

9. The display device of claim 8, wherein the photosensor is configured such that the voltage of the first node corresponds to Vd−

(Rr*((Vd−

Vs)/(Rr+Rp))), wherein Vd represents the driving voltage, Vs represents the source voltage, Rr represents a resistance of the reset switching element turned on, and Rp represents a resistance of the sensing element turned on.

10. The display device of claim 8, wherein the sensing element senses light when the first gate line and the second gate line are supplied with a gate-off voltage, and a sensing signal is output to the sensing signal line according to the voltage of the first node when the first gate line is supplied with a gate-on voltage, after the sensing element senses the light.

11. The display device of claim 8, wherein the sensing element is turned on when the second gate line is supplied with the gate-on voltage.

12. The display device of claim 8, wherein the control terminal of the sensing element comprises:

a light blocking film positioned on an insulation substrate;

a lower gate electrode connected to the light blocking film; and

an upper gate electrode facing the lower gate electrode with respect to the output terminal and the input terminal of the sensing element.

13. The display device of claim 12, wherein the light blocking film transmits light having a wavelength band sensed by the sensing element and blocks light out of the wavelength band.

14. The display device of claim 12, wherein the source voltage line is positioned in a same layer as the upper gate electrode, and the sensing signal line and the driving voltage line are positioned in a same layer.

15. A method of driving a display device, the method comprising:

applying a gate-off voltage to a control terminal of a sensing switching element of the display device;

applying a gate-on voltage to a control terminal of a sensing element of the display device and a control terminal of a reset switching element of the display device, from a same gate line; and

sensing light by applying a gate-off voltage to the control terminal of the sensing element and the control terminal of the reset switching element,

wherein the sensing switching element is connected to the sensing signal line and directly connected to a first node, the sensing element is connected to the first node and a source line transmitting a source voltage, the reset switching element is connected to the first node and a driving voltage line transmitting a driving voltage, and the driving voltage line is different from a gate line connected to the sensing switching element.

16. The method of claim 15, wherein a voltage of the first node corresponds to Vd−

(Rr*((Vd−

Vs)/(Rr+Rp))), wherein Vd represents the driving voltage, Vs represents the source voltage, Rr represents a resistance of the reset switching element turned on, and Rp represents a resistance of the sensing element turned on.

17. The method of claim 15, further comprising outputting a sensing signal to the sensing signal line according to the voltage of the first node when the gate-on voltage is applied to the control terminal of the sensing switching element, after the sensing element senses the light.

18. The method of claim 15, wherein the control terminal of the sensing element comprises:

a light blocking film positioned on an insulation substrate;

a lower gate electrode connected to the light blocking film; and

an upper gate electrode facing the lower gate electrode with respect to the output terminal and the input terminal of the sensing element.

19. A touch panel comprising:

a first gate line;

a second gate line;

a sensing line;

a voltage driving line;

a voltage source line;

a scan driver configured to drive the gate lines;

a photosensor; and

at least one pixel configured to display an image,

wherein the photosensor panel comprises;

a switching transistor including an output terminal connected to the sensing signal line, a control terminal connected to the first gate line, and an input terminal continuously and directly connected to a first node;

a sensing transistor including an output terminal connected to the first node, a control terminal connected to the second gate line, and an input terminal connected to the source voltage line, the sensing transistor configured to sense light; and

a reset transistor including an output terminal connected to the first node, a control terminal connected to the same second gate line, and an input terminal connected to the driving voltage line.

20. The touch panel of claim 19, further comprising a voltage driver configured to provide a source voltage to the source line and a driving voltage to the driving voltage line such that the voltage of the first node corresponds to Vd−

(Rr*((Vd−

Vs)/(Rr+Rp))), wherein Vd represents the driving voltage, Vs represents the source voltage, Rr represents a resistance of the reset transistor turned on, and Rp represents a resistance of the sensing transistor turned on.

21. The touch panel of claim 19, wherein the scan driver is configured to sequentially apply a gate-off voltage to the first and second gate lines to activate the sensing transistor to sense light, a gate-on voltage to the first gate line to cause the photosensor to output contact information to the sensing line, and the gate-on voltage to the second gate line to reduce a leakage current of the sensing transistor.

22. The touch panel of claim 19, wherein the control terminal of the sensing transistor comprises:

a light blocking film positioned on an insulation substrate;

a lower gate electrode connected to the light blocking film; and

an upper gate electrode facing the lower gate electrode with respect to the output terminal and the input terminal of the sensing element.