Display with integrated pressure sensing utilizing capacitive coupling to circuit elements

• US 10,402,000 B2
• Filed: 03/04/2013
• Issued: 09/03/2019
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Jamshidi-Roudbari, Abbas, Chang, Shih Chang, Yu, Cheng-Ho, Chang, Ting-Kuo
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): Nokham, James S
• Application Number:
  US13/784,509
• Publication Number:
  US 20140247239A1
• Time in Patent Office: 2,374 Days
• Field of Search: 345173-174, 349 12, 178 1806
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A touch sensitive device that can detect the amount of pressure being applied to a touch screen from a user or other external object is provided. A spacer of the touch screen can be coated with a layer of conductive material and the change in capacitance between the spacer and various circuit elements of the touch screen can be measured. The change in capacitance can be correlated to the amount of pressure being applied to the touch screen, thus providing a method to determine the pressure being applied. During operation of the device, the system can time multiplex touch, display and pressure sensing operations so as to take advantage of an integrated touch and display architecture.

Claims

1. A display, comprising:

a first layer having a plurality of spacers formed thereon;

a second layer formed with a separation relative to the first layer, the second layer including a plurality of circuit elements,

the plurality of circuit elements including;

guard shield electrodes configurable for coupling to ground in a touch sensing mode and configurable for coupling with at least one of the plurality of spacers in a pressure sensing mode, and

a plurality of common electrodes; and

sense circuitry configured to;

measure a change in a first capacitive coupling, the first capacitive coupling between at least two of the plurality of common electrodes in the touch sensing mode, the first change in capacitive coupling due to objects proximate to the display,

measure a change in a second capacitive coupling, the second capacitive coupling between at least one of the guard shield electrodes and a first spacer of the plurality of spacers in the pressure sensing mode, and

determine an amount of pressure based on at least the change in the second capacitive coupling,

wherein the first spacer is formed over a boundary between the at least one guard shield electrode and at least one of the plurality of common electrodes.

2. The display of claim 1, further comprising conductive material formed over the plurality of spacers for coupling with the plurality of circuit elements in the pressure sensing mode.

4. The display of claim 2, wherein the conductive material formed over the plurality of spacers is electrically connected together.

5. The display of claim 4, wherein the conductive material formed over the plurality of spacers is configured for receiving a stimulation signal.

6. The display of claim 2, wherein the conductive material formed over the plurality of spacers is patterned.

7. The display of claim 1, wherein the plurality of circuit elements are further configurable for operating with the first layer in a display mode.

8. The display of claim 1, wherein the plurality of common electrodes include a plurality of row electrodes and a plurality of column electrodes.

9. The display of claim 1, wherein the sense circuitry is further configured to measure a change in a third capacitive coupling, the third capacitive coupling between the at least one of the plurality of common electrodes and the first spacer of the plurality of spacers, wherein the determination of the amount of pressure is further based on change in the third capacitive coupling.

10. The display of claim 1, wherein the display is a liquid crystal display (LCD), and the second layer includes a common electrode layer of the LCD.

11. The display of claim 10, wherein the first layer is a color filter layer, and the plurality of spacers are sub-photo spacers formed on the color filter layer.

3. The display of clam 2, wherein the conductive material formed over the plurality of spacers is floating.

12. A controller, comprising:

a plurality of drivers configured for stimulating one or more drive lines in a stackup;

a plurality of sense channels configured for detecting changes in capacitive coupling in the stackup; and

a processor capable of

during a touch sensing mode;

configuring the plurality of sense channels for detecting a change in a first capacitive coupling between a plurality of common electrodes located on a layer due to object proximity at the stackup, and

configuring at least one guard shield electrode located on the layer to be grounded, and

during a pressure sensing mode;

configuring the plurality of sense channels for detecting a change in a second capacitive coupling between at least one spacer and the at least one guard shield electrode located on the layer,

configuring the plurality of sense channels for detecting a change in a third capacitive coupling between the at least one spacer and at least one common electrode of the plurality of common electrodes, the changes in the second capacitive coupling and the third capacitive coupling indicative of an amount of object-pressure on the stackup,

wherein the at least one spacer is formed over a boundary between the at least one guard shield electrode and the at least one common electrode.

13. The controller of claim 12, the processor further capable of configuring the plurality of drivers for stimulating those drive lines at which object proximity has been detected.

14. The controller of claim 12, the processor further capable of configuring the plurality of drivers for stimulating conductive material formed over the at least one spacer in the stackup.

15. The controller of claim 12, the processor further capable of configuring the plurality of sense channels for detecting a change in a third capacitive coupling between at least one spacer in the stackup and at least one of a plurality of rows, or at least one of a plurality of columns or both.

16. The controller of claim 15, the processor further capable of determining the amount of object pressure based on the change in the third capacitive coupling.

17. A method for sensing pressure in a display, comprising:

forming conductive material over a plurality of spacers on a first layer of the display;

detecting a change in a first capacitive coupling between a plurality of common electrodes on a second layer of the display in a touch sensing mode;

grounding a plurality of guard shield electrodes in the touch sensing mode;

determining an amount of object proximity based on the detected changes in the first capacitive coupling at the plurality of common electrodes;

detecting a change in a second capacitive coupling between one or more of the plurality of spacers and one or more of the plurality of guard shield electrodes in a pressure sensing mode, the plurality of guard shield electrodes on the second layer of the display and included in a plurality of circuit elements;

detecting a change in a third capacitive coupling between the one or more of the plurality of spacers and one or more of the plurality of common electrodes; and

determining an amount of object pressure on the display based on the detected change in the second capacitive coupling between the one or more of the plurality of spacers and one or more of the plurality of guard shield electrodes and the detected change in the third capacitive coupling between the one or more of the plurality of spacers and the one or more of the plurality of common electrodes.

18. The method of claim 17, further comprising operating the plurality of circuit elements with the first layer in a display mode.

19. The method of claim 17, further comprising:

configuring the plurality of circuit elements to form a plurality of row electrodes, a plurality of column electrodes, and the plurality of guard shield electrodes; and

generating signals at one or more of the plurality of row electrodes, one or more of the plurality of column electrodes, and one or more of the plurality of guard shield electrodes indicative of the amount of object pressure in the pressure sensing mode.

20. The method of claim 17, further comprising forming the plurality of spacers over a boundary between a row electrode, a column electrode, or one or more of the plurality of guard shield electrodes.

21. The method of claim 17, further comprising floating the conductive material formed over each spacer.

22. The method of claim 21, further comprising stimulating the conductive material formed over the plurality of spacers with an AC signal.

23. The method of claim 17, further comprising electrically connecting the conductive material formed over the plurality of spacers.

24. The method of claim 17, further comprising:

driving the common electrodes to display an image on the display,

wherein detecting the change in first capacitive coupling, detecting the second change in capacitive coupling, and driving the common electrodes are time multiplexed.