Integrated touch screen

• US 8,730,196 B2
• Filed: 03/04/2013
• Issued: 05/20/2014
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steven Porter, Yousefpor, Marduke, Chang, Shih Chang, Zhong, John Z.
• Primary Examiner(s): Chow, Van
• Application Number:
  US13/784,714
• Publication Number:
  US 20130176281A1
• Time in Patent Office: 442 Days
• Field of Search: 345/173, 345/174
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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

Abstract

Displays with integrated touch sensing circuitry are provided. An integrated touch screen can include multi-function circuit elements that form part of the display circuitry of the display system that generates an image on the display, and also form part of the touch sensing circuitry of a touch sensing system that senses one or more touches on or near the display. The multi-function circuit elements can be, for example, capacitors in display pixels of an LCD that are configured to operate as display circuitry in the display system, and that may also be configured to operate as touch circuitry of the touch sensing system. For example, one or more circuit elements of the display pixel stackup can form a conductive portion of the touch sensing system, such as a charge collector, which can be operated with switches and conductive lines to sense touch.

Claims

1. A touch screen comprising:

a group of display pixels, each display pixel including display circuitry that includes a circuit element; and

touch sensing circuitry in one or more of the display pixels including capacitive sensor circuitry that includes a common electrode acting as a charge collector and first and second conductive lines connectable to the charge collector by first and second switches, respectively;

wherein the first and second switches are directly connected to the common electrode and at least a portion of one of the charge collector, the first conductive line, the second conductive line, the first switch, and the second switch includes the circuit element.

2. The touch screen of claim 1, wherein the charge collector is configurable for receiving a charge through one of the first and second switches, and providing an indication of an amount of charge on the charge collector through the other of the first and second switches.

3. The touch screen of claim 2, wherein the charge collector is configurable for forming a self capacitance to ground when charged through one of the first and second switches, and varying its self capacitance when an object is proximate to the charge collector.

4. The touch screen of claim 1, wherein the charge collector and first and second conductive lines are configurable for operating as a common electrode, xVcom line, and data line of a display pixel in a display mode.

5. The touch screen of claim 1, wherein the first and second switches perform non-overlapping switching of the charge collector.

6. The touch screen of claim 1, wherein the charge collector includes common electrodes of a display pixel pair.

7. The touch screen of claim 6, wherein the charge collector further includes conductive structures that connect the common electrodes, the conductive structures being formed in a plane of the common electrodes.

8. The touch screen of claim 1, wherein the second conductive lines include data lines of the display circuitry.

9. The touch screen of claim 1, wherein the first switch is a thin film transistor.

10. A touch screen system including the touch screen of claim 1, the touch screen system comprising:

a voltage drive that outputs a voltage to the second conductive line;

a switch controller that controls the first and second switches in accordance with the output voltage to generate a charge on the charge collector, and to transfer an amount of charge on the charge collector to the first conductive line; and

a charge sensing circuit that detects the amount of charge transferred to the first conductive line;

wherein the amount of charge on the charge collector is based on an object proximate to the conductive portion.

11. The touch screen system of claim 10, wherein the switch controller controls the first and second switches to connect the second conductive line to, and to disconnect the first conductive line from, the conductive portion when the voltage drive outputs the voltage, and controls the first and second switches to disconnect the second conductive line from, and to connect the first conductive line to, the conductive portion to transfer the amount of charge on the charge collector to the first conductive line.

12. The touch screen of claim 1, wherein the conductive portion includes the circuit element of a first display pixel electrically connected by a bridge to the circuit element of a second display pixel.

13. The touch screen of claim 12, wherein the first and second display pixels are adjacent to each other.

14. The touch screen of claim 12, wherein the first switch is located in the first display pixel and the second switch is located in the second display pixel.

15. The touch screen of claim 1, wherein the charge collector is connected to a plurality of charge collectors to form a larger charge collector.

16. The touch screen of claim 15, wherein the plurality of charge collectors are configurable for operating together as touch sensing circuitry in a touch sensing mode.

17. The touch screen of claim 10, wherein the switch controller is configurable for controlling the first and second switches by applying a gate voltage to the first and second switches.

18. The touch screen of claim 17, wherein the gate voltage is applied such that a constant gate to source voltage is maintained while the source voltage is changing.