Multipoint touch surface controller

• US 9,262,029 B2
• Filed: 08/20/2014
• Issued: 02/16/2016
• Est. Priority Date: 05/02/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steven P., Krah, Christoph H., Huppi, Brian Q.
• Primary Examiner(s): HORNER, JONATHAN R
• Application Number:
  US14/464,524
• Publication Number:
  US 20140362048A1
• Time in Patent Office: 545 Days
• Field of Search: 345173-178
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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 multipoint touch surface controller is disclosed herein. The controller includes an integrated circuit including output circuitry for driving a capacitive multi-touch sensor and input circuitry for reading the sensor. Also disclosed herein are various noise rejection and dynamic range enhancement techniques that permit the controller to be used with various sensors in various conditions without reconfiguring hardware.

Claims

1. A method of detecting inputs on a touch sensor panel including a plurality of touch nodes formed at intersections of a first plurality of drive electrodes and a plurality of sense electrodes, comprising:

acquiring a first capacitance image of the touch sensor panel in response to stimulating each of the first plurality of drive electrodes with a first set of periodic waveforms having a first predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes;

acquiring a second capacitance image of the touch sensor panel in response to stimulating each of the first plurality of drive electrodes with a second set of periodic waveforms having a second predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes; and

determining a location of at least one touch based on the acquired first capacitance image and second capacitance image,

wherein at least two of the plurality of drive electrodes are stimulated consecutively with periodic waveforms with different predetermined frequencies in a single scan.

2. The method of claim 1, comprising:

acquiring a third capacitance image of the touch sensor panel in response to stimulating each of the first plurality of drive electrodes with a third set of periodic waveforms having a third predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes.

3. The method of claim 2, comprising:

suppressing noise based on the acquired first capacitance image and second capacitance image.

4. The method of claim 3, wherein suppressing noise comprises applying a majority rules algorithm to the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

5. The method of claim 3, wherein suppressing noise comprises calculating a median value of the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

6. The method of claim 3, wherein suppressing noise comprises calculating an average of the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

7. The method of claim 1, wherein the first plurality of drive electrodes are stimulated row-by-row.

8. The method of claim 1, comprising:

selecting the first predetermined frequency and the second predetermined frequency based on a noise environment.

9. The method of claim 8, wherein the first predetermined frequency and the second predetermined frequency are selected such that a pass band at the first predetermined frequency does not overlap with a pass band at the second frequency.

10. A controller for a touch sensor panel including a plurality of touch nodes formed at intersections of a first plurality of drive electrodes and a plurality of sense electrodes, the controller including one or more programs for comprising:

means for acquiring a first capacitance image of the touch sensor panel in response to stimulating each of the first plurality of drive electrodes with a first set of periodic waveforms having a first predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes;

means for acquiring a second capacitance image of the touch sensor panel in response to stimulating each of the second plurality of drive electrodes with a second set of periodic waveforms having a second predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes; and

means for determining a location of at least one touch based on the acquired first capacitance image and second capacitance image,

wherein at least two of the plurality of drive electrodes are stimulated consecutively with periodic waveforms with different predetermined frequencies in a single scan.

11. The controller of claim 10, comprising:

means for acquiring a third capacitance image of the touch sensor panel in response to stimulating each of the third plurality of drive electrodes with a third set of periodic waveforms having a third predetermined frequency and measuring capacitive couplings of the stimulated first plurality of drive electrodes and at least one of the sense electrodes.

12. The controller of claim 11, comprising:

means for suppressing noise based on the acquired first capacitance image and second capacitance image.

13. The controller of claim 12, wherein means for suppressing noise comprises means for applying a majority rules algorithm to the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

14. The controller of claim 12, wherein means for suppressing noise comprises means for calculating a median value of the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

15. The controller of claim 12, wherein means for suppressing noise comprises means for calculating an average of the measured capacitive couplings of the first, second, and third capacitance images on a per touch node basis.

16. The controller of claim 10, wherein the first plurality of drive electrodes are stimulated row-by-row.

17. The controller of claim 10, comprising:

means for selecting the first predetermined frequency and the second predetermined frequency based on a noise environment.

18. The controller of claim 17, wherein the first predetermined frequency and the second predetermined frequency are selected such that a pass band at the first predetermined frequency does not overlap with a pass band at the second frequency.