Methods and systems for detecting a position-based attribute of an object using digital codes

• US 9,012,793 B2
• Filed: 09/11/2013
• Issued: 04/21/2015
• Est. Priority Date: 11/15/2005
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Reynolds, J. Kurth
• Primary Examiner(s): Nguyen, Kevin M
• Application Number:
  US14/024,302
• Publication Number:
  US 20140168144A1
• Time in Patent Office: 587 Days
• Field of Search: 345/173, 178/18.06, 178/19.07
• US Class Current: 178/18.06
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• 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 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

Methods, systems and devices are described for detecting a position-based attribute of a finger, stylus or other object with a touchpad or other sensor having a touch-sensitive region that includes a plurality of electrodes. Modulation signals for one or more electrodes are produced as a function of any number of distinct digital codes. The modulation signals are applied to an associated at least one of the plurality of electrodes to obtain a resultant signal that is electrically affected by the position of the object. The resultant signal is demodulated using the plurality of distinct digital codes to discriminate electrical effects produced by the object. The position-based attribute of the object is then determined with respect to the plurality of electrodes from the electrical effects.

Claims

1. A controller for simultaneously detecting the presence of multiple input objects within a sensing region of a capacitive position sensor, the controller comprising:

drive circuitry configured to simultaneously transmit a first signal with a first transmitter electrode and a second signal with a second transmitter electrode, wherein the first and second signals are distinct signals based on distinct digital codes, respectively; and

receiver circuitry configured to receive resultant signals from a plurality of receiver electrodes proximate to and capacitively coupled with the first transmitter electrode and the second transmitter electrode;

wherein the controller is configured to detect the simultaneous presence of multiple input objects within the sensing region based on the resultant signals; and

wherein the controller is configured to adjust a frequency of the first and second signals based on observed noise in the resultant signals.

2. The controller of claim 1, wherein the controller is further configured to determine a position-based attribute of an input object proximate the capacitive position sensor based on the resultant signals.

3. The controller of claim 1, wherein the drive circuitry is configured to simultaneously transmit the first signal with the first transmitter electrode and transmit the second signal with the second transmitter electrode by one of:

frequency modulating a carrier signal according to the distinct digital codes; and

amplitude modulating a carrier signal according to the distinct digital codes.

4. The controller of claim 1, wherein the drive circuitry is configured to simultaneously transmit the first signal with the first transmitter electrode and transmit the second signal with the second transmitter electrode by phase modulating a carrier signal according to the distinct digital codes.

5. The controller of claim 1, wherein the distinct digital codes are mathematically independent.

6. The controller of claim 1, wherein the distinct digital codes comprise a code selected from the group consisting of Walsh-Hadamard codes, Gold codes, Kasami Codes, and Barker Codes.

7. The controller of claim 1, wherein the distinct digital codes comprise Pseudo-Random codes.

8. The controller of claim 1, wherein the distinct digital codes are binary.

9. The controller of claim 1, further configured to generate the distinct digital codes by shifting a digital bit sequence.

10. The controller of claim 1, wherein the drive circuitry comprises respective connections between the controller and the first and second transmitter electrodes.

11. The controller of claim 10, wherein the respective parallel connections comprise a first signal path between the controller and the first transmitter electrode, and a second signal path between the controller and the second transmitter electrode.

12. The controller of claim 11, wherein the first and second signal paths each comprise at least one of an amplifier and a driver.

13. A method of simultaneously detecting the presence of multiple input objects within a sensing region of a capacitive sensor, the method comprising:

simultaneously transmitting a first signal with a first transmitter electrode and a second signal with a second transmitter electrode, wherein the first and second signals are distinct signals based on distinct digital codes, respectively;

receiving resultant signals with a plurality of receiver electrodes proximate to and capacitively coupled with the first transmitter electrode and the second transmitter electrode;

detecting the simultaneous presence of multiple input objects based on the resultant signals; and

adjusting a frequency of the first and second signals based on observed noise in the resultant signals.

14. The method of claim 13, further comprising determining a position-based attribute of the at least one input object proximate a surface of the capacitive position sensor based on the resultant signals.

15. The method of claim 13, wherein the distinct digital codes are generated by shifting a digital bit sequence.

16. The method of claim 13, wherein simultaneously transmitting comprises:

transmitting the first signal using a first signal path coupled to the first transmitter electrode; and

transmitting the second signal using a second signal path coupled to the second transmitter electrode.

17. The method of claim 16, wherein the first and second signal paths each comprise at least one of an amplifier and a driver.

18. The method of claim 13, wherein simultaneously transmitting comprises one of:

frequency modulating a carrier signal according to the distinct digital codes; and

amplitude modulating a carrier signal according to the distinct digital codes.

19. An input device for simultaneously detecting the presence of multiple input objects within a sensing region of a capacitive position sensor, the input device comprising:

a first transmitter electrode, a second transmitter electrode, and a plurality of receiver electrodes proximate to and configured to be capacitively coupled with the first transmitter electrode and the second transmitter electrode; and

a controller configured to simultaneously transmit a first signal with the first transmitter electrode and a second signal with the second transmitter electrode, and to receive resultant signals from the plurality of receiver electrodes, wherein the first and second signals are distinct signals based on distinct digital codes, respectively;

wherein the controller is configured to detect the simultaneous presence of multiple input objects within a sensing region based on the resultant signals; and

wherein the controller is configured to adjust a frequency of the first and second signals based on observed noise in the resultant signals.

20. The input device of claim 19, wherein the controller is further configured to determine a position-based attribute of the at least one input object proximate a surface of the capacitive position sensor based on the resultant signals.