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

• US 9,348,477 B2
• Filed: 12/23/2014
• Issued: 05/24/2016
• 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:
  US14/580,914
• Publication Number:
  US 20150185920A1
• Time in Patent Office: 518 Days
• US Class Current: 1/1
• 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 capacitive sensing with a position sensor, the method comprising:

simultaneously transmitting a first modulation signal with a first transmit electrode and a second modulation signal with a second transmit electrode, wherein the first and modulation signal and the second modulation signal are distinct modulation signals based on different distinct digital codes of a plurality of distinct digital codes and a carrier signal, and further wherein at least one distinct digital code of the plurality of distinct digital codes indicates driven and un-driven states;

receiving a resultant signal from a receive electrode, wherein the resultant signal comprises electrical effects associated with the first modulation signal and the second modulation signal; and

determining a first position of a first object and a second position of a second object based on the electrical effects resultant.

2. The method of claim 1 wherein each of the plurality of distinct digital codes comprises a code selected from the set of codes consisting of;

binary codes and ternary codes.

3. The method of claim 1 wherein the simultaneously transmitting the first modulation signal with the first transmit electrode and the second modulation signal with the second transmit electrode comprises modulating at least one characteristic of the carrier signal, the modulating the at least one characteristic the carrier signal selected from the group consisting of:

frequency modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes;

amplitude modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes; and

phase modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes.

4. The method of claim 1, wherein each distinct digital code of the plurality of distinct digital codes is mathematically independent from all other distinct digital code of the plurality of distinct digital codes.

5. The method of claim 1, wherein each of the plurality of distinct digital codes comprises a code selected from the group consisting of Walsh-Hadamard codes, Gold codes, Kasami Codes, Barker Codes and Pseudo-Random Digital Codes.

6. The method of claim 1, wherein the first position comprises a position of the first object with respect to a sensing region of the position sensor.

7. A controller for a capacitive position sensor, the controller comprising:

drive circuitry configured to simultaneously apply a first modulation signal to a first transmit electrode and a second modulation signal to a second transmit electrode, wherein the first modulation signal and the second modulation signal are distinct signals based on different distinct digital codes of a plurality of distinct digital codes and a carrier signal, and further wherein at least one distinct digital code of the plurality of distinct digital codes indicates driven and un-driven states; and

receive circuitry configured to receive a resultant signal from a receive electrode, the resultant signal comprising electrical effects associated with the first modulation signal and the second modulation signal;

wherein the controller is configured to determine a first position of a first object and a second position of a second object based on the electrical effects.

8. The controller of claim 7, wherein the plurality of distinct digital codes comprise a code selected from the set of codes consisting of:

binary codes and ternary codes.

9. The controller of claim 7, wherein the drive circuitry is configured to simultaneously apply the first modulation signal to the first transmit electrode and the second modulation signal to the second transmit electrode by modulating at least one characteristic of the carrier signal, the modulating the at least one characteristic the carrier signal selected from the group consisting of:

frequency modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes;

amplitude modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes; and

phase modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes.

10. The controller of claim 7, wherein each distinct digital code of the plurality of distinct digital codes is mathematically independent from all other distinct digital code of the plurality of distinct digital codes.

11. The controller of claim 7, wherein each of the plurality of distinct digital codes comprises a code selected from the group consisting of Walsh-Hadamard codes, Gold codes, Kasami Codes, and Barker Codes.

12. The controller of claim 7, wherein the plurality of distinct digital codes comprises a Pseudo-Random codes.

13. The controller of claim 7, wherein the controller is further configured to generate the plurality of distinct digital codes by shifting a digital bit sequence.

14. The controller of claim 7, wherein the controller is further configured to demodulate the resultant signal to remove effects of the carrier signal and the effects of the plurality of distinct digital codes to thereby discriminate electrical effects produced by the first object and the second object.

15. The controller of claim 7, wherein the controller is further configured to adjust a frequency of the carrier signal in response to electrical noise.

16. A capacitive position sensor comprising:

a plurality of transmit electrodes;

a plurality of receive electrodes; and

a controller coupled to the plurality of transmit electrodes and to the plurality of receive electrodes and configured to;

simultaneously apply a first modulation signal to a first transmit electrode and a second modulation signal to a second transmit electrode, wherein the first modulation signal and the second modulation signal are distinct modulation signals based different distinct digital codes of a plurality of distinct digital codes and a carrier signal, and further wherein at least one of the plurality of distinct digital codes indicates driven and un-driven states;

receiving resultant signals from the plurality of receive electrodes, wherein the resultant signals comprise electrical effects associated with the first modulation signal and the second modulation signal; and

determining a first position-based attribute of a first object and a second position-based attribute of a second object based on the electrical effects.

17. The position sensor of claim 16, wherein each distinct digital code of the plurality of distinct digital codes is mathematically independent fromt the other distinct digital code of the plurality of distinct digital codes.

18. The position sensor of claim 16, wherein each of the plurality of distinct digital codes comprises a code selected from the set consisting of:

binary codes and ternary codes.

19. The position sensor of claim 16, wherein the controller is configured to simultaneously apply the first modulation signal to the first transmit electrode and the second modulation signal to the second transmit electrode by modulating at least one characteristic of the carrier signal, the modulating the at least one characteristic the carrier signal selected from the group consisting of:

frequency modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes;

amplitude modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes; and

phase modulating the carrier signal according to the different distinct digital codes of the plurality of distinct digital codes.

20. The position sensor of claim 16, wherein each of the distinct digital codes comprises a code selected from the group consisting of Walsh-Hadamard codes, Gold codes, Kasami Codes, Barker Codes and Pseudo-Random codes.

21. The position sensor of claim 16, wherein the controller is further configured to generate the plurality of distinct digital codes by shifting a digital bit sequence.

22. The position sensor of claim 16, wherein the plurality of transmit electrodes is disposed in a first direction and the plurality of receive electrodes is disposed in a second direction substantially orthogonal to the first direction.

23. The position sensor of claim 16, wherein the controller is further configured to determine at least a partial image for an input object interacting with the position sensor.

24. A controller for a capacitive position sensor, the controller comprising:

drive circuitry configured to simultaneously apply a first modulation signal to a first transmit electrode and a second modulation signal to a second transmit electrode, wherein the first modulation signal comprises a carrier signal modulated according to a first distinct digital code of a plurality of distinct digital codes and the second modulation signal comprises the carrier signal modulated according to a second distinct digital code of the plurality of distinct digital codes; and

receive circuitry configured to receive a plurality of resultant signals from a plurality of receive electrodes, a first resultant signal of the plurality of resultant signals comprising first electrical effects associated with the first modulation signal and the second modulation signal,

wherein the controller is configured to determine a first position of a first object using at least the first electrical effects.

25. The controller of claim 24, further comprising a code generation module for producing the plurality of distinct digital codes.

26. The controller of claim 24, further comprising a signal generator for generating the carrier signal.

27. The controller of claim 26, wherein the signal generator comprises an oscillator.

28. The controller of claim 24, wherein the carrier signal has a periodically varying voltage.

29. The controller of claim 28, wherein the first modulation signal comprises the carrier signal amplitude modulated according to the first distinct digital code.

30. The controller of claim 28, wherein the first modulation signal comprises the carrier signal phase modulated according to the first distinct digital code.

31. The controller of claim 24, wherein the receive circuitry is further configured to determine the first position of the first object using the first electrical effects by demodulating the first resultant signal to remove effects of the carrier signal and effects of using the plurality of distinct digital codes.

32. The controller of claim 24, wherein the demodulating the first resultant signal further comprises filtering the first resultant signal.

33. The controller of claim 24, wherein the controller is further configured to be coupled to the plurality of transmit electrodes and the plurality of receive electrodes, wherein the plurality of transmit electrodes are disposed in a first direction and the plurality of receive electrodes are disposed in a second direction substantially orthogonal to the first direction.

34. The controller of claim 24, wherein the controller is further configured to determine a two-dimensional image using at least the first electrical effects.

35. The controller of claim 24, wherein the receive circuitry is further configured to receive a second resultant signal from a second receive electrode of the plurality of receive electrodes, the second resultant signal comprising second electrical effects associated with the first modulation signal and the second modulation signal, wherein the controller is further configured to determine a second position of a second object using at least the second resultant signal.

36. The controller of claim 35, wherein the controller is further configured to perform one action selected from a group of actions consisting of a scrolling action and a mode selection action in response to determining at least the first position of the first object and the second position of the second object.

37. The controller of claim 35, wherein the controller is further configured to:

identifying a user'"'"'s palm in the two-dimensional image; and

not reporting information about the user'"'"'s palm.

38. The controller of claim 35, wherein the first object is a first pointer and the second object is a second pointer and wherein the first pointer and the second pointer are each a pointing object selected from a group consisting of:

a finger and a stylus.

39. The controller of claim 35, wherein the controller is further configured to report the first position as first object coordinates and the second position as second object coordinates.

40. The controller of claim 35, wherein the first resultant signal and the second resultant signal are simultaneously received.

41. A method of capacitive sensing with a position sensor, the method comprising:

simultaneously transmitting a first modulation signal with a first transmit electrode of a plurality of transmit electrodes and a second modulation signal with a second transmit electrode of the plurality of transmit electrodes,

wherein the first modulation signal comprises a carrier signal modulated according to a first distinct digital code of a plurality of distinct digital codes and the second modulation signal comprises the carrier signal modulated according to a second distinct digital code of the plurality of distinct digital codes, and wherein the carrier signal has a periodically varying voltage;

receiving a first resultant signal from a first receive electrode, wherein the first resultant signal comprises first electrical effects associated with the first modulation signal and the second modulation signal;

receiving a second resultant signal from a second receive electrode, wherein the second resultant signal comprises second electrical effects associated with the first modulation signal and the second modulation signal;

demodulating the first and second resultant signals to remove effects of the carrier signal and effects of using the first and second distinct digital codes, and extract the first and second electrical effects; and

determining a first position of a first object and second position of a second object based on the electrical effects.

42. The method of claim 41, wherein the method further comprises adjusting a frequency of the carrier signal in response to electrical noise.

43. A controller for a capacitive position sensor, the controller comprising:

drive circuitry configured to simultaneously apply a first modulation signal to a first transmit electrode and a second modulation signal to a second transmit electrode, wherein the first modulation signal comprises a carrier signal modulated using a first distinct digital code and the second modulation signal comprises the carrier signal modulated using a second distinct digital code, and wherein the carrier signal has a periodically varying voltage; and

receive circuitry configured to;

receive a first resultant signal from a first receive electrode, the first resultant signal comprising first electrical effects associated with the first modulation signal and the second modulation signal; and

receive a second resultant signal from a second receive electrode, the second resultant signal comprising second electrical effects associated with the first modulation signal and the second modulation signal,

wherein the controller is configured to;

demodulate the first and second resultant signals to remove effects of the carrier signal and effects of using the first and second distinct digital codes, and extract the first and second electrical effects;

define a two-dimensional image using at least the first and second electrical effects; and

determine positions of a first object and a second object in a sensing region of the capacitive position sensor using the first and second electrical effects.

44. The controller of claim 43, wherein the controller is further configured to adjust a frequency of the carrier signal in response to electrical noise.