EQUALIZING PARASITIC CAPACITANCE EFFECTS IN TOUCH SCREENS

• US 20110248949A1
• Filed: 04/09/2010
• Published: 10/13/2011
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yu, Cheng Ho, Hotelling, Steven Porter, Chang, Shih Chang
• Granted Patent: US 9,285,909 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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: 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

Reduction of the effects of differences in parasitic capacitances in touch screens is provided. A touch screen can include multiple display pixels with stackups that each include a first element and a second element. For example, the first element can be a common electrode, and the second element can be a data line. The display pixels can include a first display pixel including a third element connected to the first element, and the third element can contribute to a first parasitic capacitance between the first and second elements of the first display pixel, for example, by overlapping with the second element. The touch screen can also include a second display pixel lacking the third element. The second display pixel can include a second parasitic capacitance between the first and second elements of the second display pixel. The first and second parasitic capacitances can be substantially equal, for example.

Claims

1. A touch screen comprising:

a plurality of display pixels with stackups that each include a first element and a second element, wherein the plurality of display pixels includes

a first display pixel including a third element connected to the first element, the third element contributing to a first parasitic capacitance between the first and second elements of the first display pixel, and

a second display pixel lacking the third element, the second display pixel including a second parasitic capacitance between the first and second elements of the second display pixel.

2. The touch screen of claim 1, wherein one of the first element and the second element includes a touch sensing element of touch sensing circuitry that senses a touch on or near the touch screen.

3. The touch screen of claim 1, wherein the second element of first display pixel and the second element of the second display pixel are electrically separated from each other.

4. The touch screen of claim 3, wherein the second element of the first display pixel includes a portion of a first data line of a display system of the touch screen, and the second element of the second display pixel includes a portion of a second data line of the display system.

5. The touch screen of claim 3, wherein the first element of the first display pixel includes a common electrode of the first display pixel, and the first element of the second display pixel includes a common electrode of the second display pixel.

6. The touch screen of claim 1, wherein the second display pixel includes a fourth element connected to one of the first element and the second element, the fourth element contributing to the second parasitic capacitance between the first and second elements of the second display pixel.

7. The touch screen of claim 6, wherein the first and second parasitic capacitances are substantially equal.

8. The touch screen of claim 6, wherein the second element of the first display pixel includes a portion of a first data line of a display system of the touch screen, the second element of the second display pixel includes a portion of a second data line of the display system, and the fourth element includes a wing structure connected to the second data line.

9. The touch screen of claim 6, wherein the first element of the first display pixel includes a common electrode of the first display pixel, the first element of the second display pixel includes a common electrode of the second display pixel, and the fourth element includes an extension connected to the common electrode of the second display pixel.

10. The touch screen of claim 1, wherein the second element and the third element are in different material layers of the stackup, and the third element overlaps the second element.

11. The touch screen of claim 1, wherein a first plurality of electrically connected second elements includes the second element of first display pixel and the second element of the second display pixel, and a total parasitic capacitance of the first plurality of second elements includes the first and second capacitances.

12. The touch screen of claim 11, further comprising a second plurality of connected second elements, wherein the first and second pluralities of second elements include an equal number of first display pixels, such that the total parasitic capacitances of the first and second plurality of second elements are balanced.

13. The touch screen of claim 1, the touch screen incorporated within a computing system.

14. A method of manufacturing a touch screen including a layout of a plurality of display pixels with stackups that each include a first element and a second element, the method comprising:

forming, at a first placement in the layout, a first display pixel including a first configuration that includes the first and second element, the first configuration being associated with a first parasitic capacitance between the first and second elements, and

forming, at a second placement in the layout, a second display pixel including a second configuration that includes the first and second elements, the second configuration being different than the first configuration and associated with a second parasitic capacitance, such that total parasitic capacitances of a plurality of second elements are balanced.

15. The method of claim 14, wherein forming the first display pixel includes forming a third element connected to the first element, the third element contributing to the first parasitic capacitance, and forming the second display pixel includes forming a fourth element connected to one of the first and second elements, the fourth element contributing to the second parasitic capacitance.

16. The method of claim 15, wherein the first and second parasitic capacitances are substantially equal.

17. The method of claim 15, wherein the second element includes a data line of a display system of the touch screen, and the total parasitic capacitances are balanced among the data lines of different columns of the display pixels.

18. The method of claim 14, wherein a first plurality of electrically connected second elements includes the second element of first display pixel and the second element of the second display pixel, and a total parasitic capacitance of the first plurality of second elements includes the first and second capacitances

19. The method of claim 18, further comprising forming a second plurality of connected second elements, wherein the first and second pluralities of second elements include an equal number of first display pixels, such that the total parasitic capacitances of the first and second plurality of second elements is balanced.

20. A touch screen comprising:

a plurality of display pixels with stackups that each include a common electrode and a data line portion, wherein the plurality of display pixels includes

a first display pixel including a first conductive element connected to the common electrode, wherein an overlap of the first conductive element and the data line portion contributes to a first parasitic capacitance between the common electrode of the first display pixel and the data line portion, and

a second display pixel lacking the first conductive element, the second display pixel including a second parasitic capacitance between the common electrode of the second display pixel and the data line portion.

21. The touch screen of claim 20, wherein the second display pixel includes a second element connected to one of the common electrode and the data line portion, the second element contributing to the second parasitic capacitance between the common electrode and the data line portion of the second display pixel.

22. The touch screen of claim 20, wherein the first and second data line portions are portions of the same data line.