Common electrode connections in integrated touch screens

• US 9,195,331 B2
• Filed: 12/06/2011
• Issued: 11/24/2015
• Est. Priority Date: 12/06/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yu, Cheng-Ho, Ge, Zhibing, Xu, Ming, Chang, Shih Chang
• Primary Examiner(s): Okebato, Sahlu
• Application Number:
  US13/312,940
• Publication Number:
  US 20130141343A1
• Time in Patent Office: 1,449 Days
• Field of Search: 345/173, 345/175
• US Class Current: 1/1
• 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 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]

Abstract

Common electrodes (Vcom) of integrated touch screens can be segmented into electrically isolated Vcom portions that can be operated as drive lines and/or sense lines of a touch sensing system. The touch screen can include high-resistivity connections between Vcom portions. The resistivity of the high-resistivity connections can be high enough so that touch sensing and image display can be performed by the touch screen, and the high-resistivity connections can provide an added functionality by allowing a charge build up on one of the Vcom portions to be spread to other Vcom portions and/or discharged from system by allowing charge to leak through the high-resistivity connections. In this way, for example, visual artifacts that result from charge build up on a Vcom portion can be reduced or eliminated.

Claims

1. An integrated touch screen comprising:

a plurality of display pixels disposed in an active region of the touch screen;

a plurality of common electrodes including first common electrodes and second common electrodes, each display pixel being associated with one of the common electrodes, wherein the first common electrodes are sense common electrodes and the second common electrodes are drive common electrodes;

a plurality of first connections between the sense common electrodes or between the drive common electrodes, each first connection conductively connecting two of the sense common electrodes or two of the drive common electrodes; and

a plurality of second connections between one of the sense common electrodes and one of the drive common electrodes, each second connection conductively connecting two of the common electrodes comprising one of the sense common electrodes and one of the drive common electrodes and configured to allow a charge to leak through the second connection when the touch screen is powered on, wherein each second connection has a resistivity higher than each first connection.

2. The integrated touch screen of claim 1, further comprising:

a pixel material associated with each display pixel, wherein the pixel material is liquid crystal.

3. The integrated touch screen of claim 1, further comprising:

a stackup of material layers, the stackup including the plurality of display pixels, wherein one or more of the first or second connections connecting common electrodes includes a first material disposed in the stackup.

4. The integrated touch screen of claim 3, wherein the first material is disposed in a same material layer of the stackup as the common electrodes.

5. The integrated touch screen of claim 3, wherein the first material is disposed in a different material layer than the common electrodes.

6. The integrated touch screen of claim 1, wherein one or more of the second connections connecting common electrodes is an exclusive connection between two of the common electrodes.

7. The integrated touch screen of claim 1, further comprising:

a border region adjacent to the active region, the border region including no display pixels; and

a plurality of conductive leads, each conductive lead connected to one of the common electrodes, and at least a portion of each conductive lead being disposed in the border region.

8. The integrated touch screen of claim 7, wherein one or more of the connections between common electrodes includes one or more second connections between the conductive leads in the border region.

9. The integrated touch screen of claim 8, wherein the one or more second connections between two of the conductive leads includes a line.

10. The integrated touch screen of claim 8, further comprising:

a common conductive line, at least a portion of the common conductive line being disposed in the border region, wherein the plurality of conductive leads includes first, second, and third conductive leads conductively connected to third, fourth, and fifth common electrodes included in the plurality of first or second common electrodes, respectively, and each of the first, second, and third conductive leads is conductively connected to the common conductive line through a connection between the conductive line and the conductive lead, such that the connection between the third and fourth common electrodes includes two connections between the conductive line and the first and second conductive leads, and the connection between the fourth and fifth common electrodes includes two connections between the conductive line and the second and third conductive leads.

11. The integrated touch screen of claim 10, further comprising:

a ground conductively connected to the conductive line.

12. The integrated touch screen of claim 10, further comprising:

a plurality of data lines, wherein each display pixel includes a pixel electrode and the pixel electrode is electrically connected to one of the data lines;

a display driver that controls voltages of the data lines and the common electrodes to apply a voltage to the pixel material associated with each display pixel, wherein a luminance of each display pixel is controlled based on an amount of the voltage applied to the pixel material, and

wherein the display driver controls a voltage of the common electrodes by setting the voltage of the common electrodes to a first voltage value, the integrated touch screen further comprising;

a display common electrode voltage source that supplies a voltage at the first voltage value, wherein the conductive line is conductively connected to the display common electrode voltage source.

13. The integrated touch screen of claim 10, wherein one or more of the connections between the conductive line and the conductive lead includes a diode.

14. The integrated touch screen of claim 13, wherein the anode of each of the one or more diodes is conductively connected to the conductive line, the integrated touch screen further comprising:

a voltage source electrically connected to the conductive line, wherein a voltage level of the voltage source restricts current from the anode to the cathode of the diode, such that the diode operates as a connection from the conductive line to the conductive lead.

15. The integrated touch screen of claim 14, wherein the voltage source includes one of a ground and a fixed voltage source.

16. The integrated touch screen of claim 10, wherein one or more of the connections between the conductive line and the conductive lead includes a transistor, wherein the source and drain of the transistor are conductively connected to the conductive line and the conductive lead, and the gate of the transistor is electrically connected to a first voltage source that supplies a first voltage to the gate of the transistor, the first voltage maintaining the transistor in the off state, such that the transistor operates as the connection between the conductive line and the conductive lead.

17. The integrated touch screen of claim 16, further comprising:

a ground conductively connected to the conductive line.

18. The integrated touch screen of claim 12, wherein the display driver controls the voltage of the common electrodes by setting the voltage of the common electrodes to a second voltage value, the integrated touch screen further comprising:

a display common electrode voltage source that supplies a voltage at the second voltage value, wherein the conductive line is conductively connected to the display common electrode voltage source.

19. The integrated touch screen of claim 16, wherein the source and drain of each of the one or more transistors are conductively connected to the conductive lead and conductive line, respectively, and wherein the transistor is in the on state at a gate voltage of zero volts.

20. The integrated touch screen of claim 12, further comprising:

a touch controller that applies drive signals to one or more of the common electrodes and that receives sense signals resulting from the drive signals, the sense signals indicating an amount of touch on the touch screen, wherein each conductive lead electrically connects one of the common electrodes to at least one of the display driver and the touch controller.

21. The integrated touch screen of claim 1, wherein the sense signals are generated on one or more of the common electrodes.