Touch sensitive display device and method thereof

• US 20070091078A1
• Filed: 10/25/2006
• Published: 04/26/2007
• Est. Priority Date: 10/26/2005
• 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, Park, Jong-Woung, Uh, Kee-Han, Choi, Young-Jun
• Granted Patent: US 7,868,875 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

The present invention relates to a touch sensitive display device, the display device including a display panel unit, a sensing unit formed on the display panel unit, receiving a sensor control signal, and generating a sensor data signal based on a touch exerted on the display panel unit, an output unit generating a sensing signal based on the sensor data signal from the sensing unit, and a compensation unit adjusting the sensor control signal such that the sensing signal is bounded in a predetermined range.

Claims

1. A display device comprising:

a display panel unit;

a sensing unit formed on the display panel unit, receiving a sensor control signal, and generating a sensor data signal based on a touch exerted on the display panel unit;

an output unit generating a sensing signal based on the sensor data signal from the sensing unit; and

a compensation unit adjusting the sensor control signal such that the sensing signal is bounded in a predetermined range.

2. The display device of claim 1, further comprising a detecting unit generating a feedback signal based on the sensing signal and supplying the feedback signal to the compensation unit.

3. The display device of claim 2, wherein the compensation unit adjusts the sensor control signal based on an operating signal, and the operating signal is a difference between a target value and the feedback signal.

4. The display device of claim 3, wherein the compensation unit adjusts the sensor control signal such that the sensing signal is substantially equal to the target value.

5. The display device of claim 3, wherein the sensor control signal Vc is determined by:

$\mathrm{Vc}={\mathrm{Vc}}^{\mathrm{\prime <br><br>}}+\mathrm{Kp}\times <br><br>\mathrm{ev}<br><br>\left(t\right)+\mathrm{Ki}\times <br><br>{\int <br><br>}_0^t<br><br>\mathrm{ev}<br><br>\left(\mathrm{\tau <br><br>}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\mathrm{\tau <br><br>}+\mathrm{Kd}\times <br><br>\frac{d<br><br>\mathrm{ev}<br><br>\left(\mathrm{\tau <br><br>}\right)}{d<br><br>\left(\mathrm{\tau <br><br>}\right)},$

where Vc′

denotes a previous value of the control signal, Kp denotes a proportional gain, Ki denotes an integral gain, Kd denotes a derivative gain, and ev denotes the operating signal.

6. The display device of claim 3, wherein the compensation unit does not adjust the sensor control signal when the target value is equal to the feedback signal.

7. The display device of claim 1, wherein the compensation unit controls the sensing signal when the sensing signal is outside of the predetermined range.

8. The display device of claim 1, wherein the compensation unit performs one of proportional control, proportional-integral control, and proportional-integral-derivative control.

9. The display device of claim 1, wherein the compensation unit is implemented as an analog circuit or a digital circuit.

10. The display device of claim 1, wherein the sensing unit comprises a variable capacitor Cv and a reference capacitor Cp connected to the variable capacitor Cv, and the variable capacitor Cv has a capacitance depending on a pressure following a touch.

11. The display device of claim 10, further comprising a sensor data line transmitting the sensor data signal and connected between the variable capacitor Cv and the reference capacitor Cp.

12. The display device of claim 11, further comprising a reset transistor connected to the sensor data line and supplying the sensor control signal to the sensor data line.

13. The display device of claim 11, wherein the output unit comprises an output transistor connected to the sensor data line and generating an output signal based on the sensor data signal.

14. The display device of claim 13, wherein the output unit further comprises an amplifier generating the sensing signal based on the output signal of the output transistor.

15. The display device of claim 10, wherein the display panel unit comprises a first panel, a second panel facing the first panel, and an LC layer interposed between the first panel and the second panel.

16. The display device of claim 15, wherein the variable capacitor comprises a first electrode disposed on the first panel and a second capacitive electrode formed on the second panel.

17. The display device of claim 1, wherein the sensing unit comprises a photo-sensing element sensing light following a touch to generate a photocurrent.

18. The display device of claim 17, wherein the photo-sensing element has an input terminal connected to an input line, a control terminal connected to the sensor control signal, and an output terminal, and the photo-sensing unit outputs the photocurrent through the output terminal.

19. The display device of claim 17, further comprising:

a sensor data line transmitting the sensor data signal; and

a switching element sending the photocurrent from the photo-sensing element to the sensor data line as the sensor data signal.

20. A method of improving a touch sensing operation in a touch sensitive display device, the method comprising:

applying a sensor control signal to a sensor data line;

generating a sensor data signal from a sensing unit connected to the sensor data line based on a touch exerted on the display device;

generating a sensing signal based on the sensor data signal; and

,

bounding the sensing signal within a preset range by adjusting the sensor control signal applied to the sensor data line.

21. The method of claim 20, wherein adjusting the sensor control signal includes calculating the sensor control signal based on a previous value of the sensor control signal and an operating signal, the operating signal being a difference between a feedback signal based on the sensing signal and a target value of the sensing signal.