Multipoint touch surface controller

• US 8,816,984 B2
• Filed: 08/27/2012
• Issued: 08/26/2014
• 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 Quentin
• Primary Examiner(s): HORNER, JONATHAN R
• Application Number:
  US13/595,898
• Publication Number:
  US 20120319996A1
• Time in Patent Office: 729 Days
• Field of Search: 345173-178
• US Class Current: 345/173
• 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. An application specific integrated circuit (ASCI) connected to a touch sensor panel including a plurality of drive electrodes and a plurality of sense electrodes, the ASCI is programmed to scan the touch sensor panel, each scan of the touch sensor panel comprising:

stimulating a first drive electrode of the plurality of drive electrodes with a first periodic waveform and consecutively a second periodic waveform, wherein the second periodic waveform has a frequency different from a frequency of the first periodic waveform;

stimulating a second drive electrode of the plurality of drive electrodes with the first periodic waveform and consecutively the second periodic waveform, wherein the second drive electrode is stimulated after the stimulation of the first drive electrode; and

capturing a capacitance measurement from the plurality of sense electrodes in response to each stimulation of the drive electrodes.

2. The ASCI of claim 1, wherein scanning the touch sensor panel further comprising:

stimulating the first drive electrode with a third periodic waveform having a frequency different from the frequencies of the first and second periodic waveforms prior to stimulating the second drive electrode; and

stimulating the second drive electrode with the third periodic waveform after stimulating the first drive electrode with the first, second, and third periodic waveforms.

3. The ASIC of claim 2, further programmed to reject noise by averaging the capacitance measurements from the two frequencies that provide a best amplitude match and disposing of the capacitance measurement from the remaining frequency.

4. The ASCI of claim 1, wherein the frequencies of the waveforms used for stimulating the drive electrodes follow a frequency hopping pattern that minimizes changes to the frequencies between two consecutive stimuli.

5. The ASCI of claim 1, wherein the frequencies of the first and second periodic waveforms are selected based on a noise environment of the touch sensor panel.

6. The ASIC of claim 1, wherein scanning the touch sensor panel further comprises keeping remaining drive electrodes at ground when one of the drive electrodes is stimulated.

7. The ASIC of claim 1, wherein the pass band of the first frequency does not overlap with the pass band at the second frequency.

8. A computer-implemented method for suppressing noise in a touch sensor panel including a plurality of drive electrodes and a plurality of sense electrodes, the method comprising, in a scan of the touch sensor panel:

stimulating a first drive electrode of the plurality of drive electrodes with a first periodic waveform and consecutively a second periodic waveform, wherein the second periodic waveform has a frequency different from a frequency of the first periodic waveform;

stimulating a second drive electrode of the plurality of drive electrodes with the first periodic waveform and consecutively the second periodic waveform, wherein the second drive electrode is stimulated after the stimulation of the first drive electrode; and

capturing a capacitance measurement from the plurality of sense electrodes in response to each stimulation of the drive electrodes.

9. The method of claim 8, further comprising:

stimulating the first drive electrode with a third periodic waveform having a frequency different from the frequencies of the first and second periodic waveforms prior to stimulating the second drive electrode; and

stimulating the second drive electrode with the third periodic waveform after stimulating the first drive electrode with the first, second, and third periodic waveforms.

10. The method of claim 9, further comprising averaging the capacitance measurements from the two frequencies that provide a best amplitude match and disposing of the capacitance measurement from the remaining frequency.

11. The method of claim 8, further comprising setting the frequencies of the waveforms used for stimulating the drive electrodes to follow a frequency hopping pattern that minimizes changes to the frequencies between two consecutive stimuli.

12. The method of claim 8, further comprising selecting the frequencies of the first and second periodic waveforms based on a noise environment of the touch sensor panel.

13. The method of claim 8, further comprising keeping remaining drive electrodes at ground when one of the drive electrodes is stimulated.

14. The method of claim 8, wherein the pass band of the first frequency does not overlap with the pass band at the second frequency.