Systems and methods for signaling and interference detection in sensor devices

• US 8,847,899 B2
• Filed: 09/15/2011
• Issued: 09/30/2014
• Est. Priority Date: 09/16/2010
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Washburn, Clyde, Bohannon, Eric, Knausz, Imre, Hargreaves, Kirk
• Primary Examiner(s): Abdulselam, Abbas
• Assistant Examiner(s): OLIVER, GERALD L
• Application Number:
  US13/233,790
• Publication Number:
  US 20120068949A1
• Time in Patent Office: 1,111 Days
• Field of Search: 345156-184, 178 1801- 2004
• US Class Current: 345/173
• 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

Abstract

An input device processing system comprises a sensor module that transmits a first transmitter signal with a transmitter electrode and receives a resulting signal with a receiver electrode. The first transmitter signal comprises a first transmitter frequency, and the resulting signal comprises effects corresponding to the first transmitter signal. A demodulation module demodulates the resulting signal to produce a first signal (e.g., an upper sideband signal) and a second signal (a lower sideband signal), selectably determines a first measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode based on at least one of the first and second signals, and determines positional information for an input object based on the first measurement.

Claims

1. A processing system for an input device, the processing system comprising:

a sensor module comprising sensor circuitry, the sensor module configured to transmit a first transmitter signal with a transmitter electrode and receive a resulting signal with a receiver electrode, wherein the first transmitter signal comprises a first transmitter frequency, and the resulting signal comprises effects corresponding to the first transmitter signal; and

a demodulation module configured to acquire the resulting signal on an input, demodulate the resulting signal to produce a pair of output signals including an upper sideband signal and a lower sideband signal, selectably determine a first measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode based on at least one of the upper sideband signal and the lower sideband signal, and determine positional information for an input object based on the first measurement.

2. The processing system of claim 1, wherein a measure of interference is determined based on the lower sideband signal when the first measurement is determined based on the upper sideband signal, and wherein the measure of interference is determined based on the upper sideband signal when the first measurement is determined based on the lower sideband signal.

3. The processing system of claim 2, wherein the sensor module is configured to transmit a second transmitter signal, different from the first transmitter signal, based on the measure of interference.

4. The processing system of claim 1, wherein the demodulation module is configured to demodulate the resulting signal to produce the upper sideband signal and the lower sideband signal by mixing the resulting signal with a harmonic rejection mixer.

5. The processing system of claim 1, wherein the demodulation module is configured to demodulate the resulting signal to produce the upper sideband signal and the lower sideband signal by mixing the resulting signal with a first mixing stage and a second mixing stage;

wherein the first mixing stage comprises a first mixing frequency and a second mixing frequency, the second mixing stage comprises a third mixing frequency and a fourth mixing frequency, and wherein the third mixing frequency corresponds to the first mixing frequency and the first transmitter frequency.

6. The processing system of claim 5, wherein the second mixing frequency is in quadrature with the first mixing frequency, and the fourth mixing frequency is in quadrature with the third mixing frequency.

7. The processing system of claim 5, wherein the first measurement is determined based on the upper sideband signal when the transmitter signal frequency is greater than the first mixing frequency.

8. The processing system of claim 5, wherein the third mixing frequency corresponds to the absolute value of the difference between the first mixing frequency and the first transmitter frequency.

9. The processing system of claim 5, wherein the demodulation module is configured to demodulate the resulting signal to produce the upper sideband signal and the lower sideband signal by filtering the resulting signal with a first filter stage coupled to the first mixing stage and a second filter stage coupled to the second mixing stage.

10. The processing system of claim 9, wherein the first filter stage comprises an image reject filter.

11. The processing system of claim 5, wherein the demodulation module is further configured to demodulate the resulting signal to produce an upper sideband quadrature signal and a lower sideband quadrature signal, wherein the upper sideband quadrature signal is in quadrature with the upper sideband signal, and the lower sideband quadrature signal is in quadrature with the lower sideband signal and wherein the demodulation module is further configured to determine interference of the upper sideband quadrature signal and interference of the lower sideband quadrature signal.

12. The processing system of claim 1, wherein the demodulation module is configured to selectably determine the first measurement of the change in capacitive coupling between the transmitter electrode and the receiver electrode based on the at least one of the upper sideband signal and the lower sideband band signal by:

determining the first measurement of the change in capacitive coupling between the transmitter electrode and the receiver electrode based on the upper sideband signal; and

determining a second measurement of the change in the capacitive coupling between the transmitter electrode and the receive electrode based on the lower side band signal;

wherein the first measurement and the second measurement are determined substantially simultaneously.

13. A method of capacitive sensing, the method comprising:

transmitting a first transmitter signal with a transmitter electrode, the first transmitter signal comprising a first transmitter frequency;

receiving a resulting signal with a receiver electrode, the resulting signal comprising effects corresponding to the first transmitter signal;

demodulating the resulting signal to produce a pair of output signals including an upper sideband signal and a lower sideband signal;

selectably determining a first measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode based on at least one of the upper sideband signal and the lower sideband signal; and

determining positional information for an input object based on the first measurement.

14. The method of claim 13, wherein a measure of interference is based on the lower sideband signal when the first measurement is determined based on the upper sideband signal, and wherein the measure of interference is determined based on the upper sideband signal when the first measurement is determined based on the lower sideband signal.

15. The method of claim 14, further including transmitting a second transmitter signal, different from the first transmitter signal, based on the measure of interference.

16. The method of claim 13, wherein demodulating the resulting signal to produce the upper sideband signal and the lower sideband signal comprises mixing the resulting signal with a first mixing stage and a second mixing stage;

wherein the first mixing stage comprises a first mixing frequency and a second mixing frequency, the second mixing stage comprises a third mixing frequency and a fourth mixing frequency, and the third mixing frequency corresponds to the first mixing frequency and the first transmitter frequency, and wherein the second mixing frequency is in quadrature with the first mixing frequency, and the fourth mixing frequency is in quadrature with the third mixing frequency.

17. A capacitive sensor device comprising:

a transmitter electrode;

a receiver electrode;

a processing system communicatively coupled to the transmitter electrode and the receiver electrode, the processing system configured to;

transmit a first transmitter signal with the transmitter electrode, the first transmitter signal comprising a first transmitter frequency;

receive a resulting signal with the receiver electrode, the resulting signal comprising effects corresponding to the first transmitter signal;

demodulate the resulting signal to produce a pair of output signals including an upper sideband signal and a lower sideband signal;

selectably determine a measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode based on at least one of the upper sideband signal and the lower sideband signal; and

determine positional information for an input object based on the measurement.

18. The capacitive sensor device of claim 17, wherein a measure of interference is determined based on the lower sideband signal when the measurement is determined based on the upper sideband signal, and wherein the measure of interference is determined based on the upper sideband signal when the measurement is determined based on the lower sideband signal.

19. The capacitive sensor device of claim 18, wherein the processing system is configured to transmit a second transmitter signal, different from the first transmitter signal, based on the measure of interference.

20. The capacitive sensor device of claim 17, wherein demodulating the resulting signal to produce the upper sideband signal and the lower sideband signal comprises mixing the resulting signal with a first mixing stage and a second mixing stage;

wherein the first mixing stage comprises a first mixing frequency and a second mixing frequency, the second mixing stage comprises a third mixing frequency and a fourth mixing frequency, and the third mixing frequency corresponds to the first mixing frequency and the first transmitter frequency, and wherein the second mixing frequency is in quadrature with the first mixing frequency, and the fourth mixing frequency is in quadrature with the third mixing frequency.