Capacitance Measurement Device With Reduced Noise

• US 20170102815A1
• Filed: 10/06/2016
• Published: 04/13/2017
• Est. Priority Date: 10/07/2015
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Portmann, Lionel
• Granted Patent: US 10,444,892 B2
• Time in Patent Office: Days
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G06F 2203/0339 Touch strips, e.g. orthogonal touch strips to control cursor movement or scrolling; single touch strip to adjust parameter or to implement a row of soft keys
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means
• 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
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 2217/960775 Emitter-receiver or "fringe" type detection, i.e. one or more field emitting electrodes and corresponding one or more receiving electrodes

Abstract

A method or sensor arrangement for providing capacitive sensor detection with at least one capacitive sensor comprises a transmitting electrode and a receiving electrode. A stimulus at the transmitting electrode is generated and a signal is received from the receiving electrode and data packets are generated, each packet comprising a plurality of samples. The plurality of samples are weighted by providing less gain at a beginning and end of each packet with respect to a center of each packet; and the weighted samples are integrated to generate an output signal for each packet.

Claims

1. A method for providing capacitive sensor detection with at least one capacitive sensor comprising a transmitting electrode and a receiving electrode, the method comprising:

generating a stimulus at the transmitting electrode,

receiving a signal from the receiving electrode and generating data packets, each packet comprising a plurality of samples;

weighting the plurality of samples by providing less gain at a beginning and end of each packet with respect to a center of each packet; and

integrating the weighted samples to generate an output signal for each packet.

2. The method according to claim 1, wherein a stimulus comprises a sequence of pulses.

3. The method according to claim 2, wherein each pulse alternates between ground and a supply voltage.

4. The method according to claim 1, wherein a gain distribution is symmetrical with respect to the center of each packet and a gain distribution curve is selected from a group of gain curves consisting of a Gaussian curve, a Hamming window, a Hanning window, and a Blackman window.

5. The method according to claim 1, wherein weighting is performed by applying gain to the analog signals received from the columns or rows.

6. The method according to claim 1, wherein weighting is performed by applying gain to the digital signals during post processing of each packet.

7. The method according to claim 1, wherein the capacitive sensor is a touch sensor.

8. The method according to claim 7, wherein a plurality of touch sensors are arranged in a matrix comprising columns and rows and packets of samples are sampled in parallel from each column or row.

9. The method according to claim 7, wherein a plurality of touch sensors are arranged in a matrix comprising columns and rows and packets of samples of different columns/rows are sampled sequentially using multiplexing.

10. The method according to claim 7, wherein a plurality of touch sensors are formed by horizontal and vertical electrodes arranged in a matrix.

11. The method according to claim 7, wherein a plurality of touch sensors are arranged in a matrix and wherein horizontal and vertical electrodes of the matrix are arranged in different layers.

12. The method according to claim 1, wherein four receiving electrodes are associated with the transmitting electrode and form a three-dimensional position detection sensor.

13. The method according to claim 12, wherein the four receiving electrodes are arranged in a frame-like fashion.

14. The method according to claim 13, wherein the four receiving electrodes surround a display or a touchpad sensor.

15. A sensor arrangement with at least one capacitive sensor comprising:

a transmitting electrode configured to receive a stimulus,

a receiving electrode capacitively coupled with the transmitting electrode and configured to receive a signal from the transmitting electrode, and

an evaluation circuit coupled with the receiving electrode and configured to generate data packets, each packet comprising a plurality of samples, wherein the plurality of samples are weighted by providing less gain at a beginning and end of each packet with respect to a center of each packet, and wherein the evaluating circuit is further configured to integrate the weighted samples to generate an output signal for each packet.

16. The sensor arrangement according to claim 15, wherein a packet of the stimulus comprises a sequence of pulses.

17. The sensor arrangement according to claim 16, wherein each pulse alternates between ground and a supply voltage.

18. The sensor arrangement according to claim 15, wherein a gain distribution is symmetrical with respect to the center of each packet and a gain distribution curve is selected from a group of gain curves consisting of a Gaussian curve, a Hamming window, a Hanning window, and a Blackman window.

19. The sensor arrangement according to claim 15, wherein gain is applied to the analog signals received from the receiving electrode.

20. The sensor arrangement according to claim 15, wherein gain is applied to the digital signals during post processing of each packet.

21. The sensor arrangement according to claim 15, wherein a plurality of touch sensors are arranged in a matrix comprising columns and rows and packets of samples are sampled in parallel from each column or row.

22. The sensor arrangement according to claim 15, wherein the capacitive sensor is a touch sensor.

23. The sensor arrangement according to claim 22, wherein a plurality of touch sensors are arranged in a matrix comprising columns and rows and packets of samples of different columns/rows are sampled sequentially using multiplexing.

24. The sensor arrangement according to claim 22, wherein a plurality of touch sensors are formed by horizontal and vertical electrodes arranged in a matrix.

25. The sensor arrangement according to claim 22, comprising a plurality of touch sensors are arranged in a matrix and wherein horizontal and vertical electrodes of the matrix are arranged in different layers.

26. The sensor arrangement according to claim 15, wherein four receiving electrodes are associated with the transmitting electrode and form a three-dimensional position detection sensor.

27. The sensor arrangement according to claim 26, wherein the four receiving electrodes are arranged in a frame-like fashion.

28. The sensor arrangement according to claim 27, wherein the four receiving electrodes surround a display or a touchpad sensor.