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

• US 8,952,916 B2
• Filed: 09/11/2013
• Issued: 02/10/2015
• 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:
  US14/024,312
• Publication Number:
  US 20140168145A1
• Time in Patent Office: 517 Days
• Field of Search: 178/18.06, 178/19.07, 345/173
• US Class Current: 345/173
• 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 method of detecting a position of an input object with respect to a touch-sensitive region, comprising the steps of:

simultaneously applying a first one of a plurality of distinct modulation signals to a first electrode and a second one of the plurality of distinct modulation signals to a second electrode to obtain resultant signals that are electrically affected by the position of the input object, wherein each of the plurality of distinct modulation signals is based on a different one of a plurality of distinct digital codes;

demodulating the resultant signals using the plurality of distinct digital codes to thereby discriminate electrical effects produced by the input object; and

determining the position of the input object from the electrical effects.

2. The method of claim 1, wherein a first one of the distinct digital codes comprises a shifted digital bit sequence of a second one of the distinct digital codes.

3. The method of claim 1, further comprising adjusting a frequency of the first and second signals based on observed noise in the resultant signals.

4. The method of claim 1, wherein simultaneously applying comprises:

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

applying the second modulation signal using a second signal path coupled to the second transmitter electrode.

5. The method of claim 4, wherein the first and second signal paths each comprise at least one of an amplifier and a driver.

6. The method of claim 1, wherein simultaneously applying comprises frequency modulating a carrier signal according to the distinct digital codes.

7. The method of claim 1, wherein simultaneously applying comprises phase modulating a carrier signal according to the distinct digital codes.

8. The method of claim 1, wherein simultaneously applying comprises amplitude modulating a carrier signal according to the distinct digital codes.

9. The method of claim 1, wherein the distinct digital codes are mathematically independent.

10. The method of claim 1, wherein each of a plurality of the distinct digital codes comprises a shifted digital bit sequence of another one of the plurality of distinct digital codes.

11. The method of claim 1, wherein the distinct digital codes comprise Pseudo-Random codes.

12. The method of claim 1, wherein the distinct digital codes are binary.

13. A controller for a position sensor, comprising:

drive circuitry configured to simultaneously transmit a first signal based on a first one of a plurality of mathematically independent binary codes with a first transmitter electrode, and to transmit a second signal based on a second one of the plurality of mathematically independent binary codes with a second transmitter electrode; and

receiver circuitry coupled to at least one receiver electrode and configured to receive electrical effects associated with the first and second signals;

wherein the controller is configured to determine a position-based attribute of an input object based on the electrical effects.

14. The controller of claim 13, wherein the first and second digital codes define the first signal to be in phase with the second signal during a first time, and the first signal to be out of phase with the second signal during a second time.

15. The controller of claim 13, wherein each of the plurality of mathematically independent binary codes comprises a shifted version of another one of the plurality of mathematically independent binary codes.

16. The controller of claim 13, wherein the drive circuitry is further configured to simultaneously transmit a third signal based on a third one of a plurality of mathematically independent binary codes with a third transmitter electrode.

17. The controller of claim 13, further comprising a code generation module configured to generate each of the distinct digital codes.

18. The controller of claim 13, wherein the drive circuitry comprises 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.

19. The controller of claim 18, wherein the first and second signal paths each comprise at least one of an amplifier and a driver.

20. An 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 apply a first one of a plurality of distinct modulation signals to a first signal path connecting the controller to the first electrode, and a second one of the plurality of distinct modulation signals to a second signal path connecting the controller to the second electrode, wherein each of the plurality of distinct modulation signals is based on a different one of a plurality of distinct digital codes;

receive resultant signals that are electrically affected by the position of the input object from the;

plurality of receiver electrodes;

demodulate the resultant signals using the plurality of distinct digital codes to thereby discriminate electrical effects produced by the input object; and

determine the position of the input object from the electrical effects.