CHIRP SIGNAL TOUCH SENSOR

• US 20140118290A1
• Filed: 10/31/2012
• Published: 05/01/2014
• Est. Priority Date: 10/31/2012
• Status: Abandoned Application

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Bakken, Vemund Kval
• Application Number:
  US13/665,756
• Publication Number:
  US 20140118290A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

In one embodiment, an apparatus includes a drive electrode, a sense electrode, a detector, and a controller. The drive electrode is stimulated by an electric signal that has a frequency that varies in time. The sense electrode is capacitatively coupled to the drive electrode. The detector performs a measurement associated with the sense electrode. The controller determines whether a touch on the touch sensor occurred by determining whether the measurement deviates from an expected value by more than an amount.

Claims

1. An apparatus comprising:

a signal generator operable to generate an electric signal having a frequency that varies in time;

a drive electrode of a touch sensor operable to be stimulated by the electric signal;

a sense electrode of a touch sensor capacitatively coupled to the drive electrode;

a detector electrically coupled to the sense electrode and operable to perform a measurement associated with the sense electrode; and

a controller operable to determine whether a touch on the touch sensor occurred by determining whether the measurement deviates from an expected value by more than an amount.

2. The apparatus of claim 1 further comprising a filter associated with a variable pass band, wherein the pass band varies according to the frequency of the electric signal.

3. The apparatus of claim 2, wherein the filter is operable to vary the pass band in order to pass the frequency of the electric signal.

4. The apparatus of claim 1 further comprising a filter operable to filter out a frequency associated with a noise signal.

5. The apparatus of claim 1, wherein an amplitude of the electric signal varies according to the frequency of a noise signal.

6. The apparatus of claim 5, wherein the amplitude of the electric signal is greatest when the frequency of the electric signal is a harmonic of the frequency of the noise signal.

7. The apparatus of claim 1, wherein the detector measures a capacitance associated with the drive electrode and the sense electrode.

8. A method comprising:

generating, by a signal generator, an electric signal having a frequency that varies in time;

stimulating a drive electrode of a touch sensor with the electric signal;

performing, by a detector, a measurement associated with a sense electrode capacitatively coupled to the drive electrode;

determining, by a controller, whether a touch occurred in response to a determination whether the measurement deviated from an expected value by an amount.

9. The method of claim 9 further comprising the step of varying a variable pass band associated with a filter in order to pass the frequency of the electric signal.

10. The method of claim 9 further comprising the step of filtering out, by a filter, a frequency associated with a noise signal.

11. The method of claim 9, wherein an amplitude of the electric signal varies in time according to the frequency of a noise signal.

13. The method of claim 9, wherein the measurement is of a capacitance associated with the drive electrode and the sense electrode.

12. The method of claim 12, wherein the amplitude of the electric signal is greatest when the frequency of the electric signal is a harmonic of the frequency of the noise signal.

14. A system comprising:

a generator element operable to generate an electric signal having a frequency that varies in time;

a drive element operable to be stimulated by the electric signal;

a sense element capacitatively coupled to the drive element;

a detecting element electrically coupled to the sense element and operable to perform a measurement associated with the sense element; and

a control element operable to determine whether a touch occurred by determining whether the measurement deviates from an expected value by more than an amount.

15. The system of claim 14 further comprising a filter element associated with a variable pass band, wherein the pass band varies according to the frequency of the electric signal.

16. The system of claim 15, wherein the filter element is operable to vary the pass band in order to pass the frequency of the electric signal.

17. The system of claim 14 further comprising a filter element operable to filter out a frequency associated with a noise signal.

18. The system of claim 14, wherein an amplitude of the electric signal varies according to the frequency of a noise signal.

19. The system of claim 18, wherein the amplitude of the electric signal is greatest when the frequency of the electric signal is a harmonic of the frequency of the noise signal.

20. The system of claim 14, wherein the measurement is of a capacitance associated with the drive element and the sense element.