Firmware Methods and Devices for a Mutual Capacitance Touch Sensing Device

• US 20110050618A1
• Filed: 08/25/2009
• Published: 03/03/2011
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Murphy, Thomas, Leong, Keen Hun, Rathburn, Kevin
• Granted Patent: US 8,334,849 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 1/3215 Monitoring of peripheral devices
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

Disclosed are various embodiments of methods and devices for operating a processor or host controller in a mutual capacitance sensing device. Methods and devices for sorting motion reports provided to a host controller or other processor in a mutual capacitance sensing device, reporting touch points to a host controller or other processor in a mutual capacitance sensing device, improving noise robustness and navigation performance in a mutual capacitance sensing device, determining a touch area of a user'"'"'s finger on a touch panel or touchpad of a mutual capacitance sensing device, and avoiding false wakeups and minimizing power consumption in a mutual capacitance sensing device having a touch panel or touchpad are described.

Claims

1. A method of sorting motion reports in a processor of a mutual capacitance sensing device, comprising:

(a) tracking individual touch points of a user on a touch panel or touchpad of the sensing device;

(b) reporting a plurality of individual touch points to registers of the sensing device;

(c) sorting, in the processor, the plurality of individual touch points according to touch identification (“

Touch ID”

) or to touch force (“

Touch Force”

);

(d) if Touch ID is employed to sort touch points, mapping a first touch point having a smallest Touch ID associated therewith to a first register location and mapping a second touch point having a largest Touch ID associated therewith to a last register location, and

(e) if Touch Force is employed to sort touch points, mapping the first touch point having a highest force associated therewith to the first register location, and mapping the second touch point having a lowest force associated therewith to the last register location.

2. The method of claim 1, further comprising repeating steps (d) and (e) for additional touch points.

3. The method of claim 1, wherein steps (a) through (e) are carried out by firmware embedded in the processor.

4. The method of claim 3, wherein the firmware comprises computer code loaded into on-chip ROM.

5. The method of claim 4, wherein the firmware further comprises patch code loaded into on-chip RAM by a host controller after power up.

6. The method of claim 4, wherein a firmware reset is performed after power up.

7. The method of claim 1, further comprising determining a number of touch point data packets that have been stored in the registers.

8. The method of claim 1, wherein touch point data packets are employed to organize data associated with the touch points.

9. The method of claim 8, wherein data associated with individual touch point data packets include one or more of Touch ID, Touch Force, touch point state, X positions, Y positions, and area values.

10. The method of claim 1, wherein Touch Force is pre-selected by a user or the manufacturer of the processor.

11. The method of claim 1, wherein Touch ID is pre-selected by a user or the manufacturer of the processor.

12. A method of reporting touch points in a mutual capacitance sensing device, comprising:

(a) tracking individual touch points of a user on a touch panel or touchpad of the sensing device;

(b) reporting a plurality of individual touch points to registers of a processor;

(c) determining, in the processor, whether a particular touch point from among the reported plurality of individual touch points is a new touch point or an existing touch point;

(d) if the touch point is determined to be a new touch point, determining in the processor whether a touch force value associated with the new touch point is greater than a first threshold and then identifying the new touch point in the processor as a touch, and if the touch force value is less than the first threshold then identifying the touch point in the processor as a hover;

(e) if the touch point was previously detected as a hover, determining in the processor whether the touch force value associated with the touch point is greater than the first threshold and then identifying the touch point in the processor as a touch, and if the touch force value is less than the first threshold then identifying the touch point in the processor as a hover;

(f) if the touch point was previously detected as a touch, determining in the processor whether the touch force value associated with the touch point is greater than a second threshold and then identifying the touch point in the processor as a touch, and if the touch force value is less than the second threshold then identifying the touch point in the processor as a hover, and

(g) repeating steps (a) through (f) in the registers and processor until all the reported individual touch points have been identified as touches or hovers.

13. The method of claim 12, wherein the reported individual touch points are processed in the processor to identify swipes.

14. The method of claim 12, wherein the reported individual touch points are processed in the processor to identify flings.

15. The method of claim 12, wherein steps (a) through (g) are carried out by firmware embedded in the processor.

16. The method of claim 15, wherein the firmware comprises computer code loaded into on-chip ROM.

17. The method of claim 16, wherein the firmware further comprises patch code loaded into on-chip RAM by a host controller after power up.

18. The method of claim 16, wherein a firmware reset is performed after power up.

19. The method of claim 12, wherein the first and second thresholds are updated and adjusted by the processor in accordance with the touch force values associated with the identified touches and hovers.

20. The method of claim 12, wherein the plurality of individual touch points are reported to the processor by the registers.

21. A method of improving noise robustness and navigation performance in a mutual capacitance sensing device, comprising:

(a) determining, in a processor, whether noise levels in touch point data acquired from a touch panel or touchscreen forming a portion of the sensing device exceed a noise threshold, and

(b) if the noise levels exceed the threshold, increasing the rate at which touch point data are acquired for a predetermined period of time.

22. The method of claim 21, further comprising reducing the rate at which touch point data are acquired after the predetermined period of time has elapsed.

23. The method of claim 21, further comprising determining if the touch point data are representative of touch point jittering or flickering, and if not terminating increasing the rate at which touch point data are acquired for the predetermined period of time.

24. The method of claim 21, wherein a user can selectively enable and disable increasing the rate at which touch point data are acquired for the predetermined period of time when noise levels exceed the threshold.

25. A method of improving noise robustness and navigation performance in a mutual capacitance sensing device, comprising:

(a) determining, in a processor, whether noise levels in touch point data acquired from a touch panel or touchscreen forming a portion of the sensing device exceed a noise threshold, and

(b) if the noise levels exceed the threshold, increasing the number of touch point values employed to calculate an average touch value for a given x, y position on a touch panel of the sensing device.

26. The method of claim 25, further comprising reducing the number of touch point values employed to calculate the average touch value for the x, y position on the touch panel when noise levels fall below the threshold.

27. The method of claim 25, further comprising determining if the touch point data are representative of touch point jittering or flickering, and if not, terminating increasing the number of touch point values employed to calculate the average touch value.

28. The method of claim 25, wherein a user can selectively enable and disable increasing the number of touch point values employed to calculate the average touch value for the given x, y position on the touch panel of the sensing device.

29. A method of improving noise robustness and navigation performance in a mutual capacitance sensing device, comprising:

(a) determining, in a processor, whether noise levels in touch point data acquired from a touch panel or touchscreen forming a portion of the sensing device exceed a noise threshold, and

(b) if the noise levels exceed the threshold, decreasing the rate at which darkframe reference values associated with the sensing device are adapted.

30. The method of claim 29, further comprising increasing the rate at which darkframe reference values associated with the sensing device are adapted when noise levels fall below the threshold.

31. The method of claim 29, further comprising determining if the touch point data are representative of touch point jittering or flickering, and if not, terminating decreasing the rate at which darkframe reference values associated with the sensing device are adapted.

32. The method of claim 29, wherein a user can selectively enable and disable reducing the rate at which darkframe reference values associated with the sensing device are adapted according to noise levels.

33. A method of improving noise robustness and navigation performance in a mutual capacitance sensing device, comprising:

(a) determining, in a processor, whether noise levels in touch point data acquired from a touch panel or touchscreen forming a portion of the sensing device exceed a noise threshold, and

(b) if the noise levels exceed the threshold, prolonging for a predetermined period of time the duration over which a touch point remains indicated as a current touch point.

34. The method of claim 33, wherein the predetermined period of time is host controlled using register settings.

35. The method of claim 33, further comprising determining if the touch point data are representative of touch point jittering or flickering, and if not, terminating prolonging for the predetermined period of time the duration over which the touch point remains indicated as the current touch point.

36. The method of claim 33, wherein a user can selectively enable and disable prolonging for the predetermined period of time the duration over which the touch point remains indicated as the current touch point.

37. A method of determining a touch area of a user'"'"'s finger on a touch panel or touchpad in a mutual capacitance sensing device, comprising:

(a) determining, in a processor of the sensing device, which center sense cell in the touch panel or touchpad is generating a highest touch point signal level and determining such highest touch point signal level;

(b) determining touch point signal levels corresponding to cells adjacent to the center cell;

(c) for those adjacent cells where signal levels corresponding thereto meet or exceed a predetermined percentage of the highest touch point signal level, designating such cells as touch cells together with the center cell, and

(d) determining a touch area of the touch panel or touchpad on the basis of the touch cells.

38. The method of claim 37, wherein the adjacent cells are disposed vertically and horizontally to either side of the center cell.

39. The method of claim 38, further comprising determining a first value proportional to the number of horizontal touch cells having signal levels exceeding the threshold.

40. The method of claim 39, further comprising determining a second value proportional to the number of vertical touch cells having signal levels exceeding the threshold.

41. The method of claim 40, wherein the first and second values are scaled in respect of one another to produce a number representative of the touch area.

42. A method of avoiding false wakeups and minimizing power consumption in a mutual capacitance sensing device having a touch panel or touchpad, comprising:

(a) operating the sensing device in a rest mode having a first power consumption mode associated therewith where a processor periodically searches for touches on the touch panel or touchscreen s at a first predetermined rate, and

(b) in an absence of detecting a touch on the touch panel or touchpad over a first predetermined period of time, shifting the sensing device using the processor to a second power consumption mode that is lower than the first power consumption mode where the processor periodically searches for touches on the touch panel or touchscreen at a second predetermined rate that is lower than the first predetermined rate.

43. The method of claim 42, wherein the first predetermined period of time ranges between about 15 seconds and about 60 seconds.

44. The method of claim 42, further comprising in the absence of detecting a touch on the touch panel or touchpad over a second predetermined period of time that is longer than the first predetermined period of time, shifting the sensing device using the processor to a third power consumption mode that is lower than the second power consumption mode where the processor periodically searches for touches on the touch panel or touchscreen at a third predetermined rate that is lower than the second predetermined rate.

45. The method of claim 44, wherein the second predetermined period of time ranges between about 15 seconds and about 60 seconds.

46. The method of claim 42, further comprising shifting the sensing device to a run mode using the processor when a touch is detected.

47. The method of any of claims 42, 43, 44 or 45, further comprising shifting the sensing device to a provisional run mode when a touch is detected.

48. The method of claim 47, further comprising shifting the sensing device to a run mode when a predetermined number of touches have been detected over a preset period of time.

49. The method of claim 47, further comprising shifting the sensing device to the last rest mode in which it was operating prior to operating in the provisional run mode when a predetermined number of touches have not been detected over a preset period of time.