Equalizing parasitic capacitance effects in touch screens

• US 9,285,909 B2
• Filed: 04/09/2010
• Issued: 03/15/2016
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Chang, Shih Chang, Hotelling, Steven Porter, Yu, Cheng Ho
• Primary Examiner(s): Moon, Seokyun
• Application Number:
  US12/757,896
• Publication Number:
  US 20110248949A1
• Time in Patent Office: 2,167 Days
• Field of Search: 345/174
• US Class Current: 1/1
• 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 respective common electrode and a respective second element, wherein the plurality of display pixels includes;

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

a second display pixel lacking the third element and including a fourth element, the fourth element contributing to a second parasitic capacitance between the respective common electrode and the respective second element of the second display pixel such that the first and second parasitic capacitances are substantially equal.

2. The touch screen of claim 1, wherein one of the respective common electrode and the respective 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 respective second element of the first display pixel and the respective second element of the second display pixel are electrically separated from each other.

4. The touch screen of claim 3, wherein the respective 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 respective 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 1, wherein the fourth element is connected to one of the respective common electrode and the respective second element of the second display pixel.

6. The touch screen of claim 5, wherein the respective second element of the first display pixel includes a portion of a first data line of a display system of the touch screen, the respective 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.

7. The touch screen of claim 5, wherein the fourth element includes an extension connected to the respective common electrode of the second display pixel.

8. The touch screen of claim 1, wherein the respective second element of the first display pixel and the third element are in different material layers of the stackup, and the third element overlaps the respective second element.

9. The touch screen of claim 1, wherein a first plurality of electrically connected second elements includes the respective second element of the first display pixel and the respective 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.

10. The touch screen of claim 9, 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.

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

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

forming, at a first placement in the layout, a first display pixel including a first configuration that includes the respective common electrode and the respective second element and a third element, the first configuration being associated with a first parasitic capacitance between the respective common electrode and the respective second element of the first display pixel, the third element contributing to the first parasitic capacitance; and

forming, at a second placement in the layout, a second display pixel including a second configuration that lacks the third element and includes the respective common electrode and the respective second element and a fourth element, the second configuration being associated with a second parasitic capacitance between the respective common electrode and the respective second element of the second display pixel, the fourth element contributing to the second parasitic capacitance such that the first and second parasitic capacitances are substantially equal.

13. The method of claim 12, wherein forming the first display pixel includes connecting the third element to the respective common electrode of the first display pixel, and forming the second display pixel includes connecting the fourth element to one of the respective common electrode and the respective second element of the second display pixel.

14. The method of claim 13, wherein the respective second element includes a data line of a display system of the touch screen, and total parasitic capacitances of a plurality of second elements are balanced among the data lines of different columns of the display pixels.

15. The method of claim 12, wherein a first plurality of electrically connected second elements includes the respective second element of the first display pixel and the respective 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.

16. The method of claim 15, 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 are balanced.

17. 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 and including a second element, the second element contributing to a second parasitic capacitance between the common electrode of the second display pixel and the data line portion such that the first and second parasitic capacitances are substantially equal.

18. The touch screen of claim 17, wherein the second element is connected to one of the common electrode of the second display pixel and the data line portion.

19. The touch screen of claim 17, wherein the data line portions of the first and second display pixels are portions of the same data line.

20. A touch screen comprising:

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

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

a second display pixel lacking the third element and including a fourth element, the second display pixel having a second parasitic capacitance that includes a first portion independent of a second portion,

wherein;

the first portion of the second parasitic capacitance of the second display pixel is different from the first parasitic capacitance of the first display pixel, and

the fourth element contributes to the second portion of the second parasitic capacitance such that the first and second parasitic capacitances are substantially equal.

21. The touch screen of claim 20, wherein one of the respective first element and the respective second element includes a touch sensing element of touch sensing circuitry that senses a touch on or near the touch screen.

22. The touch screen of claim 20, wherein the respective second element of the first display pixel and the respective second element of the second display pixel are electrically separated from each other.

23. The touch screen of claim 22, wherein the respective 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 respective second element of the second display pixel includes a portion of a second data line of the display system.

24. The touch screen of claim 22, wherein the respective first element of the first display pixel includes a common electrode of the first display pixel, and the respective first element of the second display pixel includes a common electrode of the second display pixel.

25. The touch screen of claim 20, wherein the fourth element is connected to one of the respective first element and the respective second element of the second display pixel, the first parasitic capacitance is between the respective first and respective second elements of the first display pixel, and the second parasitic capacitance is between the respective first and respective second elements of the second display pixel.

26. The touch screen of claim 25, wherein the respective second element of the first display pixel includes a portion of a first data line of a display system of the touch screen, the respective 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.

27. The touch screen of claim 25, wherein the respective first element of the first display pixel includes a common electrode of the first display pixel, the respective 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 respective common electrode of the second display pixel.

28. The touch screen of claim 20, wherein the respective second element of the first display pixel and the third element are in different material layers of the stackup, and the third element overlaps the respective second element.

29. The touch screen of claim 20, wherein a first plurality of electrically connected second elements includes the respective second element of the first display pixel and the respective 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.

30. The touch screen of claim 29, 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.

31. The touch screen of claim 20, the touch screen incorporated within a computing system.

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

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

forming, at a second placement in the layout, a second display pixel including a second configuration that lacks the third element and includes the respective first and second elements and a fourth element, the second configuration being associated with a second parasitic capacitance that includes a first portion independent of a second portion,

wherein;

the first portion of the second parasitic capacitance is different from the first parasitic capacitance, and

the fourth element contributes to the second portion of the second parasitic capacitance such that the first and second parasitic capacitances are substantially equal.

33. The method of claim 32, wherein forming the first display pixel includes connecting the third element to the respective first element of the first display pixel, and forming the second display pixel includes connecting the fourth element to one of the respective first and second elements of the second display pixel.

34. The method of claim 33, wherein the respective second element includes a data line of a display system of the touch screen, and total parasitic capacitances of a plurality of second elements are balanced among the data lines of different columns of the display pixels.

35. The method of claim 32, wherein a first plurality of electrically connected second elements includes the respective second element of the first display pixel and the respective 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.

36. The method of claim 35, 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 are balanced.