METHOD FOR RAPIDLY TESTING CAPACITANCE SENSING ARRAY FAULT CONDITIONS

• US 20090250268A1
• Filed: 09/25/2008
• Published: 10/08/2009
• Est. Priority Date: 02/08/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: STATON, Kenneth L., LIM, Richard Wei Kwang
• Granted Patent: US 8,692,777 B2
• Time in Patent Office: Days
• US Class Current: 178/18.60
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

The testing of a multi-touch sensor panel for opens and shorts on its drive and sense lines is disclosed by placing a substantially ungrounded conductor diagonally over the touch sensor panel so that at least a portion of every drive line and every sense line is covered by the substantially ungrounded conductor. Pixels under the substantially ungrounded conductor can have strongly positive pixels, while pixels outside the substantially ungrounded conductor can have negative pixels. With the substantially ungrounded conductor in place, a backdrop of negative pixels is formed, and an image of touch can be obtained. By analyzing the image of touch, any opens and shorts on the drive and sense lines, any shorts between a drive and a sense line, or any open drive and sense lines can be quickly identified against the backdrop of negative pixels.

Claims

1. A method for detecting faults in a touch sensor panel, comprising:

placing a substantially ungrounded conductor diagonally across the touch sensor panel so that a plurality of drive and sense lines in the touch sensor panel are covered by the conductor;

obtaining an image of touch from the touch sensor panel; and

analyzing the image of touch to detect any faults in the touch sensor panel.

2. The method of claim 1, further comprising detecting faults by identifying drive or sense lines with strongly positive or strongly negative pixels relative to a baseline of negative pixels.

3. The method of claim 1, further comprising detecting faults by performing a histogram on the drive and sense lines to identify those drive and sense lines with anomalous pixel values.

4. The method of claim 1, further comprising detecting faults by identifying shorts between drive lines, shorts between sense lines, shorts between a drive and a sense line, open drive lines and open sense lines.

5. The method of claim 4, further comprising identifying shorts between drive lines by locating two or more drive lines with strongly positive pixel values.

6. The method of claim 4, further comprising identifying shorts between sense lines by locating two or more sense lines with strongly positive pixel values.

7. The method of claim 4, further comprising identifying an open drive line by locating a single drive line with strongly positive pixel values.

8. The method of claim 4, further comprising identifying an open sense line by locating a single sense line with strongly positive pixel values.

9. The method of claim 4, further comprising identifying a short between a drive line and a sense line by locating a single sense line with strongly negative pixel values.

10. A method for detecting faults in a touch sensor panel, comprising:

placing a substantially ungrounded conductor diagonally across the touch sensor panel to generate a expected baseline of negative pixels in an image of touch captured from the touch sensor panel; and

contrasting an actual image of touch obtained from the touch sensor panel against the expected baseline to detect any faults in the touch sensor panel.

11. The method of claim 10, further comprising detecting faults by identifying drive or sense lines with strongly positive or strongly negative pixels relative to a baseline of negative pixels.

12. The method of claim 10, further comprising detecting faults by performing a histogram on the drive and sense lines to identify those drive and sense lines with anomalous pixel values.

13. The method of claim 10, further comprising detecting faults by identifying shorts between drive lines, shorts between sense lines, shorts between a drive and a sense line, open drive lines and open sense lines.

14. The method of claim 13, further comprising identifying shorts between drive lines by locating two or more drive lines with strongly positive pixel values.

15. The method of claim 13, further comprising identifying shorts between sense lines by locating two or more sense lines with strongly positive pixel values.

16. The method of claim 13, further comprising identifying an open drive line by locating a single drive line with strongly positive pixel values.

17. The method of claim 13, further comprising identifying an open sense line by locating a single sense line with strongly positive pixel values.

18. The method of claim 13, further comprising identifying a short between a drive line and a sense line by locating a single sense line with strongly negative pixel values.

19. A test system for detecting faults in a touch sensor panel, comprising:

a support structure coupled to a substantially ungrounded conductor and configured for placing the conductor diagonally across the touch sensor panel so that a plurality of drive and sense lines in the touch sensor panel are covered by the conductor; and

test circuitry communicatively coupled for receiving an image of touch from the touch sensor panel and configured for analyzing the image of touch to detect any faults in the touch sensor panel.

20. The test system of claim 19, the test circuitry further configured for detecting faults by identifying drive or sense lines with strongly positive or strongly negative pixels relative to a baseline of negative pixels.

21. The test system of claim 19, the test circuitry further configured for detecting faults by performing a histogram on the drive and sense lines to identify those drive and sense lines with anomalous pixel values.

22. The test system of claim 19, the test circuitry further configured for detecting faults by identifying shorts between drive lines, shorts between sense lines, shorts between a drive and a sense line, open drive lines and open sense lines.

23. The test system of claim 22, the test circuitry further configured for identifying shorts between drive lines by locating two or more drive lines with strongly positive pixel values.

24. The test system of claim 22, the test circuitry further configured for identifying shorts between sense lines by locating two or more sense lines with strongly positive pixel values.

25. The test system of claim 22, the test circuitry further configured for identifying an open drive line by locating a single drive line with strongly positive pixel values.

26. The test system of claim 22, the test circuitry further configured for identifying an open sense line by locating a single sense line with strongly positive pixel values.

27. The test system of claim 22, the test circuitry further configured for identifying a short between a drive line and a sense line by locating a single sense line with strongly negative pixel values.

28. The test system of claim 19, the test circuitry at least partially integrated into a device including the touch sensor panel.

29. An apparatus for detecting faults in a touch sensor panel, comprising:

a substantially ungrounded conductor configured for placement diagonally across the touch sensor panel, the conductor shaped and sized to extend to opposite corners of the touch sensor panel so that a plurality of drive and sense lines in the touch sensor panel are covered by the conductor.

30. The apparatus of claim 29, the apparatus communicatively coupled to test circuitry configured for detecting faults by identifying drive or sense lines with strongly positive or strongly negative pixels relative to a baseline of negative pixels.

31. The apparatus of claim 29, the apparatus communicatively coupled to test circuitry configured for receiving an image of touch from the touch sensor panel and analyzing the image of touch to detect any faults in the touch sensor panel.

32. The apparatus of claim 31, the test circuitry further configured for detecting faults by performing a histogram on the drive and sense lines to identify those drive and sense lines with anomalous pixel values.

33. The apparatus of claim 31, the test circuitry further configured for detecting faults by identifying shorts between drive lines, shorts between sense lines, shorts between a drive and a sense line, open drive lines and open sense lines.

34. The apparatus of claim 33, the test circuitry further configured for identifying shorts between drive lines by locating two or more drive lines with strongly positive pixel values.

35. The apparatus of claim 33, the test circuitry further configured for identifying shorts between sense lines by locating two or more sense lines with strongly positive pixel values.

36. The apparatus of claim 33, the test circuitry further configured for identifying an open drive line by locating a single drive line with strongly positive pixel values.

37. The apparatus of claim 33, the test circuitry further configured for identifying an open sense line by locating a single sense line with strongly positive pixel values.

38. The apparatus of claim 33, the test circuitry further configured for identifying a short between a drive line and a sense line by locating a single sense line with strongly negative pixel values.

39. The apparatus of claim 33, the test circuitry at least partially integrated into a device including the touch sensor panel.