WIDE DYNAMIC RANGE CAPACITIVE SENSING

• US 20130285971A1
• Filed: 04/30/2012
• Published: 10/31/2013
• Est. Priority Date: 04/30/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: John Greer Elias, Steven Porter Hotelling
• Inventors: ELIAS, John Greer, HOTELLING, Steven Porter
• Granted Patent: US 9,201,547 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04101 2.5D-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 and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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: H03K 17/955 using a capacitive detector

Abstract

A touch sensor panel configured to detect objects touching the panel as well as objects that are at a varying proximity to the touch sensor panel. The touch sensor panel includes circuitry that can configure the panel in a mutual capacitance (near field) architecture or a self-capacitance (far field and super far field) architecture. The touch sensor panel can also include circuitry that works to minimize an effect that a parasitic capacitance can have on the ability of the touch sensor panel to reliably detect touch and proximity events.

Claims

1. :

A method of sensing proximity events, comprising;

configuring a touch sensor panel to a self-capacitance architecture;

reducing an effect of a parasitic capacitance on one or more touch signals received from the touch sensor panel; and

determining if a proximity event has occurred based on the one or more reduced parasitic capacitance effect touch signals.

2. The method of claim 1, wherein reducing the effect of the parasitic capacitance includes offsetting the effect of the parasitic capacitance on a phase of the one or more touch signals.

3. :

The method of claim 1, wherein reducing the effect of parasitic capacitance includes attenuating an amount of parasitic capacitance in the touch sensor panel.

4. :

The method of claim 3, wherein attenuating the amount of parasitic capacitance includes placing a shield in proximity to one or more touch sensor panel components and configuring the shield to carry a signal.

5. :

The method of claim 1, wherein reducing the effect of parasitic capacitance includes both offsetting the effect that the parasitic capacitance has on a phase of the one or more touch signals and attenuating an amount of parasitic capacitance in the touch sensor panel.

6. :

The method of claim 1, wherein configuring the touch sensor panel to the self-capacitance architecture includes switching a mutual capacitance touch detection hardware configuration into a self-capacitance touch detection hardware configuration.

7. :

The method of claim 1, further comprising;

scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals.

8. :

The method of claim 7, wherein determining if a proximity event has occurred further comprises;

determining a touch signal level of one or more of the reduced parasitic capacitance effect touch signals;

computing an average touch signal for one or more of the reduced parasitic capacitance effect touch signals; and

comparing the average touch signal with a pre-determined threshold value.

9. :

An apparatus for detecting proximity events, comprising;

a touch sensor panel configured to detect changes in self-capacitance;

a parasitic capacitance reduction system configured for reducing an effect of parasitic capacitance on one or more touch signals received from the touch sensor panel; and

sensing circuitry capable of determining if a proximity event has occurred based on the one or more reduced parasitic capacitance effect touch signals.

10. :

The apparatus of claim 9, wherein the touch sensor panel is further configured to be switchable to detect changes in mutual capacitance.

11. :

The apparatus of claim 9, wherein the parasitic capacitance reduction system includes a phase noise calibration system for calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals.

12. :

The apparatus of claim 9, wherein the parasitic capacitance reduction system includes a parasitic capacitance attenuation system for lowering a magnitude of the parasitic capacitance present in the touch sensor panel.

13. :

The apparatus of claim 12, wherein the parasitic capacitance reduction system includes one or more conductive shields in proximity to one or more touch sensor panel components and configured to carry a signal.

14. :

The apparatus of claim 9, wherein the parasitic capacitance reduction system includes;

a phase noise calibration system for calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals; and

a parasitic capacitance reduction system for lowering a magnitude of the parasitic capacitance present in the touch sensor panel.

15. :

The apparatus of claim 9, wherein the sensing circuitry is further capable of scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals.

16. :

The apparatus of claim 9, wherein the sensing circuitry is further capable of determining the occurrence of the proximity event by determining a touch signal level indicative of a proximity event, computing an average touch sensor panel signal level, and comparing the computed average touch panel signal level with the determined touch signal level.

17. :

A non-transitory computer readable storage medium having stored thereon a set of instructions for detecting proximity events in a touch sensor panel, that when executed by a processor causes the processor to;

configure a touch sensor panel to detect changes in a self-capacitance on a plurality of electrodes in the touch sensor panel;

reduce a parasitic capacitance effect on one or more touch signals received from the plurality of electrodes; and

determine if a proximity event has occurred based on the one or more reduced parasitic capacitive effect touch signals.

18. :

The non-transitory computer readable storage medium of claim 17, wherein configuring the touch sensor panel includes switching the touch sensor panel from a mutual capacitance touch sensor panel to a self-capacitance touch sensor panel.

19. :

The non-transitory computer readable storage medium of claim 17, wherein reducing the parasitic capacitance effect includes calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals.

20. :

The non-transitory computer readable storage medium of claim 17, wherein reducing the parasitic capacitance effect includes attenuating an amount of parasitic capacitance in a touch sensor panel.

21. :

The non-transitory computer readable storage medium of claim 20, wherein reducing the parasitic capacitance effect includes transmitting a signal on one or more conductive shields in proximity to one or more touch sensor panel components.

22. :

The non-transitory computer readable storage medium of claim 17, wherein reducing the parasitic capacitance effect include both attenuating an amount of parasitic capacitance in the touch sensor panel and calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals.

23. :

The non-transitory computer readable storage medium of claim 17, further comprising scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals.

24. :

The non-transitory computer readable storage medium of claim 17, wherein determining if the proximity event has occurred includes;

determining a touch signal value indicative of a proximity event;

computing an average electrode signal value for one or more of the reduced parasitic capacitance effect touch signals; and

comparing the average signal value with the determined touch signal value.