TOUCH PANEL AND CONTROL METHOD THEREOF

• US 20090091552A1
• Filed: 05/08/2008
• Published: 04/09/2009
• Est. Priority Date: 10/05/2007
• Status: Abandoned Application

• Current Assignee: InnoLux Corporation
• Original Assignee: CHI MEI Optoelectronics Corporation
• Inventors: LEE, Kuo-Sheng
• Application Number:
  US12/117,350
• Publication Number:
  US 20090091552A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/044 by capacitive means
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

In a touch panel having at least one pixel and/or in accordance with a method of controlling the touch panel, a first bias signal is sent to a touch-sensitive sensing capacitor of the pixel during a first time period to charge the sensing capacitor with a sensing charge. The charged sensing capacitor discharges the sensing charge, as an outputted second bias signal, during a second time period. Based on the second bias signal, a determination is made as to whether the capacitance of the sensing capacitor has changed between the first and second periods, thereby indicating whether the pixel of the touch panel has been touched.

Claims

1. A touch panel, comprising:

a controller;

at least one pixel which comprises

a touch choosing switch coupled to and controlled by the controller to turn on during a first time period and turn off during a second time period;

a read switch coupled to and controlled by the controller to turn off during the first time period and turn on during the second time period; and

a sensing capacitor having a touch-sensitive capacitance and being electrically connected with the touch choosing switch and the read switch to be charged, via the touch choosing switch, with a sensing charge during the first time period and to discharge the sensing charge, via the read switch during the second time period; and

a sense reading unit electrically connected with the sensing capacitor via the read switch for outputting a sensed output value during the second time period;

wherein the sensed output value is indicative of the whether the capacitance of the sensing capacitor has changed between the first and second periods, thereby indicating whether said pixel of the touch panel has been touched.

2. The touch panel according to claim 1, wherein a gap of the sensing capacitor is changeable by an external force applied to said pixel.

3. The touch panel according to claim 1, wherein the sense reading unit is an integrator.

4. The touch panel according to claim 1, wherein the sense reading unit comprises:

an operational amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the negative input terminal is connected with the sensing capacitor via the read switch for receiving a second bias signal generated by the sensing capacitor discharging said sensing charge, the positive input terminal receives a reference signal, and the operational amplifier outputs the sensed output value according to the second bias signal and the reference signal;

an operational capacitor connected between the negative input terminal and the output terminal of the operational amplifier; and

a controllable switch connected in parallel with the operational capacitor for resetting the operational capacitor after the switch turns on.

5. The touch panel according to claim 1, further comprising:

a position judging unit coupled to the sense reading unit for judging the touched position according to the sensed output value.

6. A touch panel, comprising at least one pixel having a first scan line, a second scan line, and a bias line, said at least one pixel further comprising:

a touch choosing switch,

a read switch, and

a sensing capacitor having a touch-sensitive capacitance,

wherein

the touch choosing switch is electrically connected with the first scan line and the bias line,

the read switch is electrically connected with the second scan line, and

the sensing capacitor is electrically connected with both the touch choosing switch and the read switch, for receiving a first bias signal from the bias line through the touch choosing switch during a first period and for outputting a second bias signal through the read switch during a second period different from the first period, wherein the second bias signal is indicative of the whether the capacitance of the sensing capacitor has changed between the first and second periods, thereby indicating whether said pixel of the touch panel has been touched.

7. The touch panel according to claim 6, wherein a gap of the sensing capacitor is changeable by an external force applied to said pixel.

8. The touch panel according to claim 6, wherein said pixel further comprises

a pixel switch electrically connected to the second scan line and a data line of the touch panel;

and

a pixel capacitor electrically connected to the pixel switch for displaying image data received from the data line via the pixel switch during the second period.

9. The touch panel according to claim 8, further comprising:

a scan control circuit electrically connected with the touch choosing switch, the read switch and the pixel switch through the first scan line, the second scan line and the bias line;

a data control circuit electrically connected with the pixel switch through the data line.

10. The touch panel according to claim 8, wherein the sensing capacitor comprises a liquid crystal capacitor and a varactor electrically connected with each other, and the pixel capacitor comprises another liquid crystal capacitor and a storage capacitor electrically connected with each other.

11. The touch panel according to claim 6, further comprising:

a scan control circuit electrically connected with the pixel switch and the touch choosing switch through the second scan line and the first scan line, respectively;

a data control circuit electrically connected with the pixel switch through the bias line which is also a data line;

wherein said sensing capacitor is configured as pixel capacitor for displaying image data received from the data line via the pixel switch during a third period different from the first and second periods.

12. The touch panel according to claim 11, wherein the sensing capacitor comprises a liquid crystal capacitor and a storage capacitor electrically connected with each other.

13. The touch panel according to claim 6, further comprising:

a sense reading unit electrically connected with the read switch for outputting a sensed output value according to the second bias signal.

14. The touch panel according to claim 13, wherein the sense reading unit is an integrator.

15. The touch panel according to claim 13, wherein the sense reading unit comprises:

an operational amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the negative input terminal is connected with the sensing capacitor via the read switch for receiving the second bias signal, the positive input terminal receives a reference signal, and the operational amplifier outputs the sensed output value according to the second bias signal and the reference signal;

an operational capacitor connected between the negative input terminal and the output terminal of the operational amplifier; and

a controllable switch connected in parallel with the operational capacitor for resetting the operational capacitor after the switch turns on.

16. The touch panel according to claim 12, wherein the liquid crystal capacitor and the storage capacitor are connected in series or in parallel.

17. A control method of a touch panel, the touch panel having at least one pixel that comprises a sensing capacitor having a touch-sensitive capacitance, the control method comprising:

transmitting a first bias signal to the sensing capacitor during a first time period to charge the sensing capacitor with a sensing charge;

causing the sensing capacitor to discharge the sensing charge as an outputted second bias signal during a second time period different from the first time period; and

based on the second bias signal, determining whether the capacitance of the sensing capacitor has changed between the first and second periods, thereby indicating whether said pixel of the touch panel has been touched.

18. The control method according to claim 17, further comprising transmitting an image data signal to a pixel capacitor of said at least one pixel during the second time period.

19. The control method according to claim 17, further comprising transmitting an image data signal to the sensing capacitor, which is also a pixel capacitor, during a third time period different from the first and second periods.

20. The control method according to claim 17, wherein an external force is applied for changing a gap of the sensing capacitor.