Touch sensing error compensation

• US 9,164,620 B2
• Filed: 09/07/2010
• Issued: 10/20/2015
• Est. Priority Date: 06/07/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steven Porter
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): Lu, William
• Application Number:
  US12/877,061
• Publication Number:
  US 20110298746A1
• Time in Patent Office: 1,869 Days
• Field of Search: 345/156, 345173-179, 345204-215, 345690-699
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

Error compensation of a touch sensing signal is provided. A touch screen can include a drive region that can be driven by a drive signal, and a sense region that can output a sense signal that includes information of a first amount of touch on or near the touch screen and information of a first amount of error. The first amount of touch can be based on the drive signal. The touch screen can include a compensation sensor that can output a compensation signal that includes information of a second amount of error, and an error compensator that can compensate for the first amount of error in the sense signal based on the second amount of error.

Claims

1. A touch screen comprising:

a drive region configured to be driven by a drive signal;

a sense region disposed adjacent to the drive region, the sense region configured to output a sense signal that includes information of a first amount of touch on or near the touch screen and information of a first amount of error, wherein the first amount of touch is based on the drive signal;

a compensation sensor disposed between the drive region and the sense region, the compensation sensor configured to output a compensation signal that includes information of a second amount of error, wherein the second amount of error is based on the drive signal; and

an error compensator configured to compensate for the first amount of error in the sense signal based on the second amount of error in the compensation signal,

wherein at least a portion of each of the first and second amounts of error is introduced into the compensation signal and the sense signal, respectively, by a same error source.

2. The touch screen of claim 1, wherein the compensation signal further includes information of a second amount of touch based on the drive signal, a ratio of the second amount of touch to the second amount of error not exceeding a ratio of the first amount of touch to the first amount of error.

3. The touch screen of claim 2, wherein the drive region includes a first conductive line in a first direction, the sense region includes a second conductive line in a second direction transverse to the first direction, the compensation sensor includes a third conductive line, the information of the first amount of touch is based on a change in a capacitance between first and second conductive lines, and the information of the second amount of touch is based on a change in a capacitance between the first and third conductive lines.

4. The touch screen of claim 1, wherein the error source includes one of an average display pixel luminance, a local temperature, and an amount of ambient light.

5. The touch screen of claim 1, wherein the drive region includes a first conductive line in a first direction, the sense region includes a second conductive line in a second direction transverse to the first direction, and the information of the first amount of touch is based on a change in a capacitance between first and second conductive lines.

6. The touch screen of claim 1, further comprising:

a plurality of sense regions; and

a plurality of compensation sensors,

wherein each compensation sensor is disposed between two sense regions.

7. The touch screen of claim 1, wherein the information of the second amount of error is based on the drive signal.

8. The touch screen of claim 7, further comprising:

a circuit capacitively coupled to the drive region, such that a first portion of the drive signal is coupled into the circuit,

wherein the circuit is further capacitively coupled to each of the sense region and the compensation sensor, such that the information of the first amount of error is based on a second portion of the first portion of the drive signal coupled into the sense region from the circuit, and the information of the second amount of error is based on a third portion of the first portion of the drive signal coupled into the compensation sensor from the circuit.

9. The touch screen of claim 8, wherein the circuit includes a portion of a display system that displays images on the touch screen.

10. The touch screen of claim 9, wherein the circuit includes a gate line of the display system.

11. A method of compensating for error in a touch sensing signal, the method comprising:

obtaining the touch sensing signal from a sense region disposed adjacent to a drive region, the touch sensing signal including information of a first amount of touch and information of a first amount of error, wherein the first amount of touch is based on a drive signal driving the drive region;

obtaining a compensation signal from a compensation sensor disposed between the drive region and the sense region, the compensation signal including information of a second amount of error, wherein the second amount of error is based on the drive signal; and

compensating for the first amount of error in the touch sensing signal based on the second amount of error in the compensation signal,

wherein at least a portion of each of the first and second amounts of error is introduced into the compensation signal and the sense signal, respectively, by a same error source.

12. The method of claim 11, wherein the compensation signal further includes second information of an amount of touch, and a ratio of the second amount of touch to the second amount of error does not exceed a ratio of the first amount of touch to the first amount of error.

13. The method of claim 11, wherein obtaining the touch sensing signal includes driving drive regions of a touch screen with drive signals and obtaining the touch sensing signal from one or more sense regions of the touch screen, the method further comprising:

obtaining information of a state of a display system that displays an image on the touch screen;

determining if the state information satisfies a first criteria; and

in accordance with a determination that the state information satisfies the first criteria, determining the second amount of error based on a predetermined value of error independent of the information of the second amount of error of the compensation signal, wherein compensating for the first amount of error is based on the predetermined value of error.

14. The method of claim 13, wherein the state information includes one of an average display pixel luminance, a local temperature, and an amount of ambient light.

15. The method of claim 13, further comprising:

in accordance with a determination that the state information does not satisfy the first criteria, calibrating the predetermined value of error based on the information of the second amount of error obtained from the compensation signal.

16. The method of claim 14, wherein the state information includes a plurality average display pixel luminances, and the first criteria is based on a difference in average display pixel luminances of two regions of display pixels of the touch screen.