DOWNSAMPLING DATA FOR CROSSTALK COMPENSATION

• US 20120113064A1
• Filed: 11/05/2010
• Published: 05/10/2012
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yousefpor, Marduke, Krah, Christoph Horst, Hotelling, Steven Porter, WHITE, Kevin J.
• Granted Patent: US 8,913,040 B2
• Time in Patent Office: Days
• US Class Current: 345/178
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally

Abstract

A touch sensitive device having circuitry to compensate for crosstalk from the device display to the device touch sensor panel is disclosed. The crosstalk compensation circuitry can include a downsampler and a crosstalk compensator. The downsampler can downsample a display image to a manageable size for transmission and processing and can then send the downsampled image to the crosstalk compensator so as to provide information about the display operation that can be used to estimate the expected amount of crosstalk caused by the display. The crosstalk compensator can estimate the amount of crosstalk based on the downsampled image and can then compensate a touch image captured by the touch sensor panel for the estimated amount, the touch image being indicative of a touch or hover event at the panel.

Claims

1. A touch sensitive device comprising:

a display configured to show a display image;

a touch sensor panel configured to capture a touch image; and

logic configured to

downsample the display image,

generate at least one compensation value based on the downsampled display image, the compensation value being indicative of interference between the display and the panel, and

apply the compensation value to the captured touch image to compensate the captured touch image for the interference.

2. The device of claim 1, wherein the logic comprises a downsampler configured to downsample the display image to a size at least as small as the size of the captured touch image.

3. The device of claim 1, wherein the logic comprises a compensator configured to generate the compensation value and apply the compensation value to the captured touch image.

4. The device of claim 1, wherein downsampling the display image comprises selectively sampling the display image to provide portions therefrom that are indicative of the interference.

5. The device of claim 1, wherein applying the compensation value comprises selectively applying the compensation value to portions of the captured touch image determined to having the interference.

6. The device of claim 1, comprising:

a memory configured to periodically store the compensation value prior to the applying.

7. The device of claim 1 incorporated into at least one of mobile phone, a digital media player, or a computer.

8. A method of compensating for crosstalk in a touch sensitive device, the method comprising:

generating a display image and a touch image;

downsampling the display image;

estimating an amount of crosstalk in the touch sensitive device based on the downsampled image; and

adjusting the touch image based on the estimated amount of crosstalk to compensate for the crosstalk.

9. The method of claim 8, wherein downsampling the display image comprises:

selecting predetermined portions of the display image indicative of the crosstalk;

downsampling the rows of the selected portions to form row-downsampled portions;

downsampling the columns of the row-downsampled portions to form single values for the selected portions; and

outputting the single values for the estimating.

10. The method of claim 9, wherein outputting the single values comprises outputting either a group of the single values or all of the single values at a time for the display image.

11. The method of claim 8, wherein estimating an amount of crosstalk comprises:

applying a crosstalk model to the downsampled image, the model correlating crosstalk amounts with display image values; and

outputting the estimated amount of crosstalk from the model.

12. The method of claim 8, wherein adjusting touch image comprises subtracting the estimated amount of crosstalk from the touch image.

13. A touch sensitive device comprising:

a display configured to display an image; and

a downsampler configured to

downsample the display image to a predetermined size for outputting, the display image indicative of crosstalk in the device, and

output the downsampled image for estimating the crosstalk and compensating therefor in the device.

14. The device of claim 13, wherein the downsampler selects portions of the display image to downsample, the selected portions indicative of the crosstalk in the device.

15. The device of claim 13, wherein the downsampler comprises a row accumulator configured to downsample the rows of the display image to form a row-downsampled image.

16. The device of claim 13, wherein downsampler comprises a column accumulator configured to downsample the columns of the display image to form a column-downsampled image.

17. The device of claim 13, wherein downsampler comprises a shift register configured to truncate the downsampled image values to a predetermined length for the outputting.

18. A touch sensitive device comprising:

a touch sensor panel configured to capture an image indicative of a touch or hover at the panel; and

a crosstalk compensator configured to

input information indicative of crosstalk at the panel,

calculate a compensation factor based on the inputted information, and

apply the compensation factor to the captured image to compensate for the crosstalk.

19. The device of claim 18, wherein crosstalk compensator comprises a crosstalk model configured to correlate crosstalk amounts with the inputted information.

20. The device of claim 18, wherein crosstalk compensator comprises a crosstalk image calculator configured to calculate the compensation factor, the compensation factor being a crosstalk image, each pixel in the crosstalk image representative of the crosstalk in a corresponding pixel in the captured image.

21. The device of claim 18, wherein crosstalk compensator comprises an image compensator configured to apply the compensation factor to the captured image, the compensation factor being a crosstalk image, each pixel in the crosstalk image representative of the crosstalk in a corresponding pixel in the captured image, and each pixel value in the crosstalk image being applied to the corresponding pixel value in the captured image.

22. The device of claim 18, wherein the compensator selects portions of the captured image to compensate for the crosstalk, the selected portions experiencing substantial crosstalk.

23. A method of compensating for crosstalk in a touch sensitive device, the method comprising:

mapping display pixels to touch pixels experiencing crosstalk;

capturing a display image from the mapped display pixels;

calculating a crosstalk compensation factor based on the captured display image;

capturing a touch image from the mapped touch pixels; and

applying the calculated compensation factor to the captured touch image to compensate for the crosstalk.

24. The method of claim 23, wherein the mapping comprises mapping multiple rows of display pixels to a corresponding row of touch pixels.

25. The method of claim 23, wherein the mapping comprises mapping selective groups of display pixels to selective groups of touch pixels proximate to the selected groups of display pixels.