System and method for diagnostics of a grid based digitizer

• US 20090025987A1
• Filed: 07/23/2008
• Published: 01/29/2009
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: N-Trig Ltd (Microsoft Corporation)
• Inventors: Moore, Jonathan, Narkiss, Niv, Tamir, Oran, Shmulevich, Roman, Perski, Haim
• Granted Patent: US 9,041,659 B2
• Time in Patent Office: Days
• US Class Current: 178/18.30
• CPC Class Codes: G06F 11/2221 to test input/output devices or peripheral units
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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

A method for testing a digitizer to determine an operative property of the digitizer, wherein the digitizer includes a sensor grid, comprises providing an input signal on a first portion of the sensor grid, detecting at least one output signal in a second portion of the sensor grid responsive to the input signal in the first portion, and determining at least one operative property of the sensor based on the at least one output signal, wherein at least the transmitting, detecting and determining is performed autonomously by the digitizer.

Claims

1. A method for testing a digitizer to determine an operative property of the digitizer, wherein the digitizer includes a sensor grid, the method comprising:

providing an input signal on a first portion of the sensor grid;

detecting at least one output signal in a second portion of the sensor grid responsive to the input signal in the first portion; and

determining at least one operative property of the sensor based on the at least one output signal, wherein at least the transmitting, detecting and determining is performed autonomously by the digitizer.

2. The method according to claim 1, wherein the method for testing a digitizer to determine an operative property of the digitizer is performed in the absence of user interaction with the digitizer.

3. The method according to claim 1 wherein the method is performed by firmware of the digitizer.

4. The method according to claim 1, wherein the sensor grid includes a first set of parallel conductive gridlines and a second set of parallel conductive gridlines, wherein the second set is positioned orthogonally from the first set to form the sensor grid.

5. The method according to claim 4, wherein the input signal is provided over one or more parallel gridlines.

6. The method according to claim 5, wherein the at least one output signal is detected from at least one gridline orthogonal to the one or more parallel gridlines on which the input signal is provided.

7. The method according to claim 5, wherein the at least one output signal is detected from at least one gridline parallel to the one or more parallel gridlines through on the input signal is provided.

8. The method according to claim 1, wherein the output signal is effected by capacitive coupling between the first portion and the second portion of the sensor grid.

9. The method according to claim 8 wherein the output signal is effected by capacitive coupling at grid junctions formed between the first and second set of parallel gridlines.

10. The method according to claim 4, wherein pairs of parallel gridlines are input to a differential amplifiers and wherein output from the differential amplifiers is sampled to produce the outputs from the sensor.

11. The method according to claim 10 comprising grounding a first input of at least one differential amplifier to detect a signal propagating on a second input of the at least one differential amplifier.

12. The method according to claim 1, comprising:

providing an input signal on all gridlines along a first axis of the grid; and

detecting output from at least one gridlines along a second axis of the grid.

13. The method according to claim 1 wherein the input signal is an AC signal.

14. The method according to claim 13, wherein the input signal is provided at a frequency used during user interaction with the digitizer for finger detection.

15. The method according to claim 1, wherein detecting includes comparing the amplitude of the output from the sensor grid to a pre-defined threshold.

16. The method according to claim 1, wherein detecting includes comparing the energy of the output from the sensor grid in a pre-defined frequency band to a pre-defined threshold.

17. The method according to claim 1, wherein detecting includes comparing the output of the sensor grid to properties of the input signal.

18. The method according to claim 1, comprising detecting a plurality of output signals of the second portion and comparing the amplitude of each output from the plurality to an average output of the plurality.

19. The method according to claim 18, comprising comparing the amplitude of each output of the plurality to an average output and a standard deviation of the average.

20. The method according to claim 8, comprising determining connectivity between gridlines of the sensor grid and circuitry of the digitizer.

21. The method according to claim 20 comprising:

providing an AC input signal on at least one first gridline of the sensor grid;

sampling an output signal from at least one second gridline crossing the at least one first gridline utilizing output circuitry of the at least one second gridline;

comparing the output signal to a threshold; and

determining that the at least one second gridline is connected to output circuitry of the digitizer responsive to the output signal being above the threshold.

22. The method according to claim 8, comprising detecting electrical breaks in gridlines of the sensor grid.

23. The method according to claim 22 comprising:

providing an AC input signal on a first end of a first gridline of the sensor grid, the first gridline including a first end and a second end;

sampling an output signal from at least one second gridline crossing the at least one first gridline closest to the second end;

comparing the output signal to a threshold; and

determining that the first gridline includes a break responsive to the output signal being below the threshold.

24. The method according to claim 1, comprising determining cross-talk between gridlines of the sensor grid.

25. The method according to claim 24 comprising:

providing an AC input signal on a gridline of the sensor grid;

sampling output signals from at least neighboring gridlines parallel the first gridline;

comparing the output signals to a threshold; and

determining that there is cross talk between the gridline on which an input signal is provided and the neighboring gridlines responsive to at least one output signal from the output signals sampled being above the threshold.

26. The method according to claim 1, comprising determining shorts between gridlines of the sensor grid.

27. The method according to claim 26 comprising:

providing an AC input signal on a gridline of the sensor grid;

sampling output signals from neighboring gridlines parallel to the first gridline;

comparing the output signals to a threshold; and

determining that there is a short between the gridline through which an input signal is transmitted and a neighboring gridline responsive to an output signal from the neighboring gridline being above the threshold.

28. The method according to claim 8, comprising determining an imbalance between gridlines of the sensor grid.

29. The method according claim 28 comprising:

providing an AC input signal on at least one first gridline of the sensor grid;

sampling an output signal from at least one differential amplifier having input from two parallel gridline crossing the at least one first gridline;

comparing the output signal to a threshold; and

determining that there is an imbalance between the two gridlines serving as input to the differential amplifier responsive to the output signal being above the threshold.

30. The method according to claim 1, comprising reporting the determined at least one operative property to a host computer associated with the digitizer.

31. The method according claim 30 comprising reporting the determined at least one operative property to a user interacting with the host computer.

32. The method according to claim 30 comprising determining if the sensor grid is operable and reporting operability of the sensor grid.

33. The method according to claim 1 comprising compensating for at least on malfunctioning property of the digitizer.

45. The method according to claim 1, comprising detecting electrical breaks in gridlines of the grid.

46. The method according to claim 45 comprising:

propagating an AC signal through a first end of an input gridline of the sensor grid associated with a first axis of the grid, the gridline including a first end and a second end; and

determining that the input gridline does not include a break responsive to the detecting from the output, a signal responsive to capacitive coupling from a gridline closest to the second end.

34. A method for determining an operative property of a sensor grid, the method comprising:

providing an AC signal on at least one first gridline of the sensor grid, the at least one first gridline associated with a first axis of the grid;

sampling output from at least one second gridline of the sensor grid, the at least one second gridline associated with a second axis of the grid, wherein the first axis and second axis cross to form the grid;

determining output signals responsive to capacitive coupling between the at least one first gridline and the at least one second gridline; and

determining an operative property of the sensor grid based on the detected signals.

35. The method according to claim 34, wherein the sampling is performed in the absence of user interaction with the digitizer.

36. The method according to claim 34, wherein the method is performed autonomously by the digitizer.

37. The method according to claim 34, comprising determining an operative property of the at least one first gridline based on the sampled output from the at least one second gridline.

38. The method according to claim 34, comprising determining an operative property of the at least one second gridline responsive to input to the at least one first gridline.

39. The method according to claim 34, wherein at least one pair of parallel conductive gridlines is input to a differential amplifier and wherein output from the differential amplifier is sampled to obtain the output from the gridlines.

40. The method according to claim 39 comprising grounding one of the inputs of the at least one differential amplifier to detect a signal propagating on the other input of the at least one differential amplifier.

41. The method according to claim 34, wherein the input signal is transmitted at a frequency used during user interaction with the digitizer for finger detection.

42. The method according to claim 34 wherein the first axis and the second axis are orthogonal to each other.

43. The method according to claim 34, comprising determining connectivity between gridlines of the sensor grid and circuitry of the digitizer.

44. The method according to claim 43 comprising:

determining that the at least one second gridline is connected responsive detecting in the output, a signal responsive to capacitive coupling between the at least one first gridline and the at least one second gridline.

47. The method according to claim 34, comprising reporting the determined at least one operative property to a host computer associated with the digitizer.

48. The method according to claim 47 comprising reporting the determined at least one operative property to a user interacting with a host computer associated with the digitizer.

49. The method according to claim 47 comprising determining if the sensor grid is operable and reporting operability of the sensor grid.

50. The method according to claim 34 comprising compensating for at least on malfunctioning property of the digitizer.

51. A method for testing a digitizer including an excitation coil configured for triggering circuitry of an object used for user interaction with the digitizer to self-determine an operative property of the excitation coil, wherein the digitizer includes a sensor grid, the method comprising:

providing an AC signal in the excitation coil, the excitation coil at least partially surrounding the sensor grid, the excitation coil configured for transmitting an excitation signal at, at least one excitation frequency;

sampling output from at least one gridline of the senor grid; and

determining that the excitation coil is connected at least on one end to connecting circuitry responsive to the output from the at least one gridline exceeding a first threshold.

52. The method according to claim 51 comprising:

determining that the excitation coil is connected on both ends to connecting circuitry responsive to the output from the at least one gridline exceeding a second threshold and displaying a peak at the at least one excitation frequency of the excitation coil.