Methods and systems for detecting a position-based attribute of an object using digital codes
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.
1. A controller for a position sensor, wherein the controller comprises:
drive circuitry configured to simultaneously transmit a first signal with a first transmitter electrode and a second signal with a second transmitter electrode, where the first and second signals are distinct signals based on distinct digital codes; and
receiver circuitry configured to receive electrical effects with at least one receiver electrode, wherein the electrical effects are associated with the first and second signals, wherein the controller is configured to determine a position-based attribute of at least one input object based on the electrical effects.
2. The controller of claim 1 , wherein the distinct digital codes are mathematically independent.
3. The controller of claim 1 , wherein the distinct 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.
4. The controller of claim 3 , wherein the distinct digital codes comprise Walsh-Hadamard codes.
5. The controller of claim 1 , wherein the distinct digital codes comprise one of Gold codes, Kasami Codes, and Barker Codes.
6. The controller of claim 1 , wherein the distinct digital codes comprise Pseudo-Random Digital codes.
7. The controller of claim 1 , wherein the controller further comprises a code generation module configured to generate each of the distinct digital codes.
8. The controller of claim 1 , wherein the drive circuitry is further configured to simultaneously transmit the first signal with a third transmitter electrode.
9. The controller of claim 1 , wherein the controller is configured to adjust at least one of the distinct digital codes based on the electrical effects.
10. The controller of claim 1 , wherein the drive circuitry is configured to simultaneously transmit a first signal with a first transmitter electrode and a second signal with a second transmitter electrode by:
amplitude modulating a carrier signal according to the distinct digital codes.
11. The controller of claim 1 , wherein the drive circuitry is configured to simultaneously transmit a first signal with a first transmitter electrode and a second signal with a second transmitter electrode by:
frequency modulating a carrier signal according to the distinct digital codes.
12. The controller of claim 1 , wherein the drive circuitry is configured to simultaneously transmit a first signal with a first transmitter electrode and a second signal with a second transmitter electrode by:
phase modulating a carrier signal according to the distinct digital codes.
13. The controller of claim 1 , wherein the drive circuitry is further configured to couple a third transmitter electrode with an electrical reference as a shield.
14. A position sensor comprising:
a plurality of transmitter electrodes disposed in a first direction;
a plurality of receiver electrodes disposed in a second direction, where the first direction is substantially orthogonal to the second direction; and
a controller coupled to the plurality of transmitter electrodes and to the plurality of receiver electrodes, the controller configured to:
simultaneously transmit a first signal with a first transmitter electrode of the plurality of transmitter electrodes and a second signal with a second transmitter electrode of the plurality of transmitter electrodes, wherein the first and second signals are distinct signals based on distinct digital codes;
receive electrical effects associated with the first and second signals with at least one receiver electrode of the plurality of receiver electrodes; and
determine a position-based attribute of at least one input object based on the electrical effects.
15. The position sensor of claim 14 , wherein the controller is further configured to determine at least a partial image.
16. The position sensor of claim 14 , wherein determining the position-based attribute of the at least one input object using the electrical effects comprises:
determining the position-based attribute of the at least one input object based on the electrical effects by determining a first measurement and a second measurement based on the electrical effects, wherein the first measurement reflects a change in capacitance between the first transmitter electrode and the at least one receiver, and wherein the second measurement reflects a change in capacitance between the second transmitter electrode and the at least one receiver electrode.
17. The position sensor of claim 14 , wherein the distinct digital codes are mathematically independent.
18. The position sensor of claim 14 , wherein the distinct 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.
19. A method of capacitive sensing with a position sensor, said method comprises:
simultaneously transmitting a first signal with a first transmitter electrode and a second signal with a second transmitter electrode, where the first and second signals are distinct signals based on distinct digital codes;
receiving electrical effects with at least one receiver electrode, wherein the electrical effects are associated with the first and second signals; and
determining a position-based attribute of at least one input object based on the electrical effects.
20. The method of claim 19 , wherein the distinct digital codes are mathematically independent.
21. The method of claim 19 , wherein the distinct 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.
22. The method of claim 19 , wherein the method further comprises simultaneously transmitting the first signal with a third transmitter electrode.
23. The method of claim 19 , wherein the method further comprises determining the position-based attribute of the at least one input object based on the electrical effects by determining a first measurement and a second measurement based on the electrical effects, wherein the first measurement reflects a change in capacitance between the first transmitter electrode and the at least one receiver, and wherein the second measurement reflects a change in capacitance between the second transmitter electrode and the at least one receiver electrode.
24. A method of detecting input with respect to a touch-sensitive region comprising a plurality of electrodes, the method comprising:
simultaneously modulating first and second electrodes of the plurality of electrodes by applying a first modulation signal to the first electrode and a second modulation signal to the second electrode, wherein the first and second modulation signals are based on first and second distinct digital codes, and wherein the applying produces a resultant signal;
demodulating the resultant signal using at least the first and second distinct digital codes to discriminate electrical effects caused by the input; and
determining a position of the input with respect to the touch-sensitive region using the electrical effects.
25. The method of claim 24 , wherein the applying produces the resulting signal in a third electrode; and wherein the determining the position of the input with respect to the touch-sensitive region using the electrical effects comprises determining a first measurement and a second measurement based on the electrical effects wherein the first measurement reflects a change in capacitance between the first electrode and the third electrode and wherein the second measurement reflects a change in capacitance between the second electrode and the third electrode.
26. A method of detecting input with respect to a touch-sensitive region comprising a plurality of electrodes, the method comprising:
simultaneously modulating first and second electrodes of the plurality of electrodes based on first and second distinct digital codes, and wherein the modulating produces a resultant signal;
demodulating the resultant signal using at least the first and second distinct digital codes to discriminate electrical effects caused by the input; and
determining a position of the input with respect to the touch-sensitive region using the electrical effects.