Sensing circuit and display device having the same

• US 20070030255A1
• Filed: 05/24/2006
• Published: 02/08/2007
• Est. Priority Date: 08/05/2005
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Cho, Man-Seung, Lee, Joo-Hyung, Choi, Young-Jun, Lee, Myung-Woo, Pak, San-Jin
• Granted Patent: US 7,839,392 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A sensing circuit is provided that senses an externally provided pressure on a panel, and includes a sensing capacitor, a first switching element, a second switching element and a third switching element; where the sensing capacitor includes a sensing electrode on the first substrate, the insulating layer and the opposite electrode; the sensing capacitor varies a capacitance based on the externally provided pressure; the first switching element is electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal; the second switching element outputs a current based on a second switching signal and a first voltage; the third switching element is electrically connected to the sensing electrode to control the current based on the variation of the capacitance of the sensing capacitor to generate a sensing signal; and where a thickness is decreased, and an image display quality is improved.

Claims

1. A sensing circuit for sensing an externally provided pressure on a panel including a first substrate, a second substrate corresponding to the first substrate to have an opposite electrode, and an insulating layer interposed between the first and second substrates, the sensing circuit comprising:

a sensing capacitor including a sensing electrode on the first substrate, the insulating layer and the opposite electrode, the sensing capacitor varying a capacitance based on the externally provided pressure;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element outputting a current based on a second switching signal and a first voltage; and

a third switching element electrically connected to the sensing electrode to control the current outputted from the second switching element based on the variation of the capacitance of the sensing capacitor to generate a sensing signal corresponding to the externally provided pressure.

2. The sensing circuit of claim 1, wherein the second switching signal has a substantially opposite phase to the first switching signal.

3. The sensing circuit of claim 1, further comprising:

a first voltage line electrically connected to the second switching element to transmit the first voltage;

a second voltage line electrically connected to the first switching element to transmit a second voltage;

a third voltage line electrically connected to the third switching element to transmit a third voltage;

a first switching line electrically connected to the first switching element to transmit the first switching signal; and

a second switching line electrically connected to the second switching element to transmit the second switching signal.

4. The sensing circuit of claim 3, wherein the first switching element comprises:

a first electrode receiving the second voltage;

a second electrode receiving the first switching signal; and

a third electrode electrically connected to the sensing electrode.

5. The sensing circuit of claim 3, wherein the second switching element comprises:

a first electrode receiving the first voltage;

a second electrode receiving the second switching signal; and

a third electrode electrically connected to the third switching element.

6. The sensing circuit of claim 3, wherein the third switching element comprises:

a first electrode electrically connected to the sensing element;

a second electrode receiving the third voltage; and

a third electrode electrically connected to the second switching element.

7. The sensing circuit of claim 1, further comprising an operational amplifier that amplifies the sensing signal.

8. A display device comprising:

a display panel including;

an array substrate;

an opposite substrate corresponding to the array substrate to have a common electrode receiving a common voltage; and

a liquid crystal layer interposed between the array substrate and the opposite substrate, the liquid crystal layer varying a thickness based on an externally provided pressure on the display panel;

a sensing array in the display panel to generate a sensing signal based on the variation of the thickness of the liquid crystal layer, the sensing array including;

a sensing capacitor including a sensing electrode on the array substrate, the liquid crystal layer and the common electrode, the sensing capacitor varying a capacitance based on the variation of the thickness of the liquid crystal layer;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element outputting a current based on a second switching signal and a first voltage; and

a third switching element electrically connected to the sensing electrode to control the current outputted from the second switching element based on the variation of the capacitance of the sensing capacitor to generate the sensing signal; and

a controlling part on the array substrate to generate location data based on the sensing signal.

9. The display device of claim 8, wherein the second switching signal has a substantially opposite phase to the first switching signal.

15. The display device of claim 8, wherein the sensing array further comprises:

a first voltage line electrically connected to the second switching element to transmit the first voltage;

a second voltage line electrically connected to the first switching element to transmit a second voltage;

a third voltage line electrically connected to the third switching element to transmit a third voltage;

a first switching line electrically connected to the first switching element to transmit the first switching signal; and

a second switching line electrically connected to the second switching element to transmit the second switching signal.

16. The display device of claim 8, further comprising an operational amplifier that amplifies a level of the sensing signal to apply the amplified sensing signal to the controlling part.

10. The display device of claim 10, wherein the array substrate further comprises:

a substrate including a display region in which the sensing electrode is formed and a peripheral region adjacent to the display region, the first, second and third switching elements being formed in the peripheral region; and

a pixel array on the substrate corresponding to the display region.

11. The display device of claim 10, wherein the pixel array comprises:

a gate line;

a data line crossing the gate line, the data line being electrically insulated from the gate line;

a pixel switching element electrically connected to the gate and data lines; and

a pixel electrode electrically connected to the pixel switching element.

12. The display device of claim 11, wherein the sensing electrode comprise a substantially same material as the gate line or the data line.

13. The display device of claim 11, wherein the sensing electrode is substantially in parallel with the data line,

the first switching element is in a first region of the peripheral region adjacent to a first end portion of the data line, and

the second and third switching elements are in a second region of the peripheral region adjacent to a second end portion of the data line.

14. The display device of claim 11, wherein the sensing electrode comprises a substantially same material as the pixel electrode.

17. A sensing circuit for sensing an externally provided pressure on a panel including a first substrate, a second substrate corresponding to the first substrate to have an opposite electrode, and an insulating layer interposed between the first and second substrates, the sensing circuit comprising:

a sensing capacitor including a sensing electrode on the first substrate, the insulating layer and the opposite electrode, the sensing capacitor varying a capacitance based on the externally provided pressure;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element electrically connected to the sensing electrode to generate a first current based on the variation of the capacitance of the sensing capacitor; and

a third switching element electrically connected to the second switching element to output a second current that has a constant level, thereby generating a third current corresponding to a variation of the first current.

18. The sensing circuit of claim 17, wherein the second switching signal has a substantially opposite phase to the first switching signal.

19. The sensing circuit of claim 17, wherein the sensing array further comprises:

a first voltage line electrically connected to the first switching element to transmit a first voltage;

a first switching line electrically connected to the first switching element to transmit the first switching signal;

a second voltage line electrically connected to the second switching element to transmit a second voltage;

a third voltage line electrically connected to the third switching element to transmit a third voltage; and

a second switching line electrically connected to the third switching element to transmit the second switching signal.

20. The sensing circuit of claim 19, wherein the first switching element comprises:

a first electrode receiving the first voltage;

a second electrode receiving the first switching signal; and

a third electrode electrically connected to the sensing electrode.

21. The sensing circuit of claim 19, wherein the second switching element comprises:

a first electrode electrically connected to the sensing electrode;

a second electrode receiving the second voltage; and

a third electrode electrically connected to the third switching element.

22. The sensing circuit of claim 19, wherein the third switching element comprises:

a first electrode receiving the second switching signal;

a second electrode receiving the third switching signal; and

a third electrode electrically connected to the second switching element.

23. The sensing circuit of claim 17, further comprising an operational amplifier that amplifies the third current.

24. A display device comprising:

a display panel including;

an array substrate;

an opposite substrate corresponding to the array substrate to have a common electrode receiving a common voltage; and

a liquid crystal layer interposed between the array substrate and the opposite substrate, the liquid crystal layer varying a thickness based on an externally provided pressure on the display panel;

a sensing array in the display panel to generate a sensing signal based on the variation of the thickness of the liquid crystal layer, the sensing array including;

a sensing capacitor including a sensing electrode on the array substrate, the liquid crystal layer and the common electrode, the sensing capacitor varying a capacitance based on the variation of the thickness of the liquid crystal layer;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element electrically connected to the sensing electrode to generate a first current based on the variation of the capacitance of the sensing capacitor; and

a third switching element electrically connected to the second switching element to output a second current that has a constant level, thereby generating the sensing signal corresponding to a variation of the first current; and

a controlling part on the array substrate to generate location data based on the sensing signal.

25. A sensing circuit for sensing an externally provided pressure on a panel including a first substrate, a second substrate corresponding to the first substrate to have an opposite electrode and an insulating layer interposed between the first and second substrates, the sensing circuit comprising:

a sensing capacitor including a sensing electrode on the first substrate, the insulating layer and the opposite electrode, the sensing capacitor varying a capacitance based on the externally provided pressure;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element electrically connected to the sensing electrode to generate a current based on the variation of the capacitance of the sensing capacitor; and

a third switching element controlling the current outputted from the second switching element based on a second switching signal.

26. The sensing circuit of claim 25, wherein the second switching signal has a substantially opposite phase to the first switching signal.

27. The sensing circuit of claim 25, further comprising an operational amplifier that amplifies the current to generate a sensing voltage.

28. The sensing circuit of claim 27, wherein the operational amplifier outputs the sensing voltage based on a readout signal that has a substantially same phase as the second switching signal.

29. The sensing circuit of claim 25, wherein the sensing array comprises:

a first voltage line electrically connected to the first switching element to transmit a first voltage;

a first switching line electrically connected to the first switching element to transmit a first switching signal;

a second switching line electrically connected to the second switching element to transmit a second voltage; and

a second switching line electrically connected to the third switching element to transmit a second switching signal.

30. The sensing circuit of claim 29, wherein the first switching element comprises:

a first electrode receiving the first voltage;

a second electrode receiving the first switching signal; and

a third electrode electrically connected to the sensing electrode.

31. The sensing circuit of claim 29, wherein the second switching element comprises:

a first electrode electrically connected to the sensing electrode;

a second electrode receiving the second voltage; and

a third electrode electrically connected to the third switching element.

32. The sensing circuit of claim 29, wherein the third switching element comprises:

a first electrode receiving the second switching signal;

a second electrode electrically connected to the second switching element; and

a third electrode outputting the current corresponding to the variation of the capacitance.

33. A display device comprising:

a display panel including;

an array substrate;

an opposite substrate corresponding to the array substrate to have a common electrode receiving a common voltage; and

a liquid crystal layer interposed between the array substrate and the opposite substrate, the liquid crystal layer varying a thickness based on an externally provided pressure on the display panel;

a sensing array in the display panel to generate a sensing signal based on the variation of the thickness of the liquid crystal layer, the sensing array including;

a sensing capacitor including a sensing electrode on the array substrate, the liquid crystal layer and the common electrode, the sensing capacitor varying a capacitance based on the thickness of the liquid crystal layer;

a first switching element electrically connected to the sensing electrode to charge the sensing capacitor based on a first switching signal;

a second switching element electrically connected to the sensing electrode to generate the sensing signal based on the variation of the capacitance of the sensing capacitor; and

a third switching element controlling the sensing signal outputted from the second switching element based on a second switching signal; and

a controlling part on the array substrate to generate location data based on the sensing signal.