EQUALIZING PARASITIC CAPACITANCE EFFECTS IN TOUCH SCREENS

• US 20160179252A1
• Filed: 02/25/2016
• Published: 06/23/2016
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: CHANG, Shih-Chang, HOTELLING, Steven P., YU, Cheng-Ho
• Granted Patent: US 10,488,980 B2
• Time in Patent Office: Days
• 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 first element and a second element, the first element disposed in a first material layer of the stackups and the second element disposed in a second material layer of the stackups, 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 of the first display pixel, the third element disposed in a third material layer of the stackups, different from the first material layer and the second material layer; and

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

2. The touch screen of claim 1, wherein the fourth element is disposed in the second material layer of the stackups.

3. The touch screen of claim 1, wherein one of the first layer and the second layer is for sensing a touch on the touch screen.

4. 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.

5. The touch screen of claim 4, further comprising a second plurality of electrically connected second elements, wherein the first and second pluralities of second elements include an equal number of second elements of first display pixels, such that the total parasitic capacitances of the first and second pluralities of second elements are balanced.

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

7. The touch screen of claim 1, wherein:

the first element is a touch electrode in a touch phase of the touch screen and a common electrode in a display phase of the touch screen;

the second element is a portion of a data line configured to transmit touch data in the touch phase and transmit image data in the display phase;

the third element is a conductive line configured to electrically connect the first display pixel to one or more other display pixels on the touch screen; and

the fourth element is a conductive extension electrically connected to the second element of the second display pixel.

8. A method for generating an image on a touch screen including a plurality of display pixels, the method comprising:

operating a first display pixel of the plurality of display pixels to display the image, the plurality of display pixels having stackups that each include a first element and a second element, the first element disposed in a first material layer of the stackups and the second element disposed in a second material layer of the stackups, the first display pixel including;

a third element connected to the first element, the third element contributing to a first parasitic capacitance of the first display pixel, the third element disposed in a third material layer of the stackup of the first display pixel, different from the first material layer and the second material layer; and

operating a second display pixel of the plurality of display pixels to display the image, the second display pixel lacking the third element and including a fourth element, the fourth element contributing to a second parasitic capacitance of the second display pixel such that the first and second parasitic capacitances are substantially equal.

9. The method of claim 8, wherein the fourth element is disposed in the second material layer of the stackups.

10. The method of claim 8, wherein one of the first layer and the second layer is for sensing a touch on the touch screen.

11. The method of claim 8, wherein the touch screen comprises a first plurality of electrically connected second elements including 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.

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

13. The method of claim 8, wherein:

the first element is a touch electrode in a touch phase of the touch screen and a common electrode in a display phase of the touch screen;

the second element is a portion of a data line configured to transmit touch data in the touch phase and transmit image data in the display phase;

the third element is a conductive line configured to electrically connect the first display pixel to one or more other display pixels on the touch screen; and

the fourth element is a conductive extension electrically connected to the second element of the second display pixel.

14. 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 of the first display pixel;

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

a third display pixel electrically connected to the first display pixel via the third element of the first display pixel.

15. The touch screen of claim 14, wherein:

the first element is a touch electrode in a touch phase of the touch screen and a common electrode in a display phase of the touch screen;

the second element is a portion of a data line configured to transmit touch data in the touch phase and transmit image data in the display phase; and

the fourth element is a conductive extension electrically connected to the second element of the second display pixel.

16. The touch screen of claim 14, 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.

17. The touch screen of claim 16, further comprising a second plurality of electrically connected second elements, wherein the first and second pluralities of second elements include an equal number of second elements of first display pixels, such that the total parasitic capacitances of the first and second pluralities of second elements are balanced.

18. The touch screen of claim 14, incorporated within a computing system.

19. The touch screen of claim 14, wherein the third element of the first display pixel electrically connects a common electrode of the first display pixel with one or more respective common electrodes of one or more other display pixels on the touch screen, including the third display pixel.

20. A method for generating an image on a touch screen including a plurality of display pixels, the method comprising:

operating a first display pixel of the plurality of display pixels to display the image, the plurality of display pixels having stackups that each include a first element and a second element, the first display pixel including a third element, the third element connected to the first element, the third element contributing to a first parasitic capacitance of the first display pixel;

operating a second display pixel of the plurality of display pixels to display the image, the second display pixel lacking the third element, the second display pixel including a fourth element, the fourth element contributing to a second parasitic capacitance of the second display pixel such that the first and second parasitic capacitances are substantially equal; and

operating a third display pixel of the plurality of display pixels to display the image, the third display pixel electrically connected to the first display pixel via the third element of the first display pixel.

21. The method of claim 20, wherein:

the first element is a touch electrode in a touch phase of the touch screen and a common electrode in a display phase of the touch screen;

the second element is a portion of a data line configured to transmit touch data in the touch phase and transmit image data in the display phase; and

the fourth element is a conductive extension electrically connected to the second element of the second display pixel.

22. The method of claim 20, wherein the touch screen comprises 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.

23. The method of claim 20, wherein the touch screen further comprises a second plurality of connected second elements, wherein the first and second pluralities of second elements include an equal number of second elements of first display pixels, such that the total parasitic capacitances of the first and second plurality of second elements are balanced.

24. The method of claim 20, wherein the third element of the first display pixel electrically connects a common electrode of the first display pixel with one or more respective common electrodes of one or more other display pixels on the touch screen, including the third display pixel.