Individual channel phase delay scheme

• US 20080157867A1
• Filed: 01/03/2007
• Published: 07/03/2008
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krah, Christoph Horst
• Granted Patent: US 8,493,330 B2
• Time in Patent Office: Days
• US Class Current: 329/304
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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

Abstract

Embodiments of the present invention are directed to processing an incoming signal by using a demodulation signal, while controlling the phase of the demodulation signal in relation to the incoming signal. The incoming signal can be processed by being mixed with the modulation signal at a mixer. The mixing may thus cause various beneficial modifications of the incoming signal, such as noise suppression of the incoming signal, rectification of the incoming signal, demodulation of the incoming signal, etc.

Claims

1. An electronic device, comprising:

stimulation circuitry configured to generate a stimulation signal and to send it to one or more traversal circuits, the one or more traversal circuits configured to receive the stimulation signal and to modify it by changing at least its phase, and output the modified stimulation signal as a first signal; and

a processing module configured to receive the first signal, the processing module further comprising a demodulation circuit including a memory configured to store a processing module specific value, and configured to generate a demodulation signal associated with the first signal and having the same phase and frequency as the first signal;

wherein the demodulation circuit controls the phase of the demodulation signal by referring to the processing module specific value.

2. The electronic device of claim 1, wherein the one or more traversal circuits include a multi-touch panel.

3. The electronic device of claim 1, wherein the one or more traversal circuits include a proximity sensor panel.

4. The electronic device of claim 1, wherein the processing module further includes a mixer and is configured to mix the first signal and the demodulation signal.

5. The electronic device of claim 4, wherein mixing the first and the demodulation signals results in a signal selected from the group consisting of:

a rectified version of the first signal, a demodulated version of the first signal, a noise suppressed version of the first signal, and a demodulated, rectified and noise suppressed version of the first signal.

6. The electronic device of claim 1, further comprising an initialization circuit configured to test various versions of the processing module specific values to determine a version for which the demodulation module produces a match to within predetermined limits between the phases of the demodulation and first signals, and save the version in the memory of the demodulation circuit.

7. The electronic device of claim 1, wherein:

the traversal circuits through which the stimulation signal travels when being modified to the first signal change over time causing the phase difference between the stimulation signal and the first signal to change over time;

the electronic device further comprises a plurality of timing specific values associated with the changes of phase difference between the stimulation and first signals over time, each timing specific value being associated with one or more time periods; and

the demodulation circuit is configured to control the phase of the demodulation signal by referring to the timing specific values as well as the processing module specific value.

8. The electronic device of claim 7, further comprising a test circuit configured to test various versions of the processing module specific value and the timing specific values in order to determine the versions of said values which result in a match to within predetermined limits between the phases of the first signal and the demodulation signal.

9. The electronic device of claim 7, further comprising a plurality of processing modules, wherein:

a different version of the first signal arrives at each processing module, at least two of said different versions having different phases; and

each processing module comprises a respective demodulation circuit whose memory includes a respective processing module specific value associated with the phase of the version of the first signal arriving at said processing module.

10. The electronic device of claim 1, wherein the electronic device is a mobile telephone.

11. The electronic device of claim 1, wherein the electronic device is a portable music player.

12. An electronic device comprising:

a multi touch panel;

a driver circuit for sending a stimulation signal to the multi touch panel; and

at least one analog channel for receiving an incoming signal from the multi touch panel, the incoming signal being related to the stimulation signal, the analog channel further comprising a demodulation circuit for generating a demodulation signal and controlling the phase of the demodulation signal so that it matches the phase of the incoming signal.

13. The electronic device of claim 12, wherein the demodulation circuit further comprises a memory, the memory comprising a channel specific phase delay value related to the phase of the incoming signal at the multi touch panel, wherein the demodulation circuit uses the channel specific phase delay value to control the phase of the demodulation signal.

14. The electronic device of claim 13, wherein the electronic device further comprises an initialization circuit, configured to test various versions of the channel specific phase delay value to determine a version which results in a demodulation signal whose phase matches the phase of the incoming signal to within predetermined limits, and save the version in the memory of the demodulation circuit.

15. The electronic device of claim 14, wherein the initialization circuit comprises a generally programmable processor running an initialization program.

16. The electronic device of claim 12, wherein the incoming signal results from the passing of the stimulation signal through the multi touch panel.

17. The electronic device of claim 12, wherein

the driver circuit is configured to send the stimulation signal to one or more of a plurality of electrodes of the multi touch panel and to periodically change the electrodes of the multi touch panel through which the stimulation signal is sent, said changing of electrodes causing a change in the phase of the incoming signal;

and

the demodulation circuit is configured to periodically change the phase of the demodulation signal to reflect the changes of phase of the incoming signal.

18. The electronic device of claim 17, wherein:

the electronic device comprises a register including a plurality of time specific phase delay values;

each time specific phase delay value is associated with one or more electrodes through which the stimulation signal can be sent and is related to the resulting phase of the incoming signal if the stimulation signal is sent to said one or more electrodes; and

the demodulation circuit is configured to periodically access different time specific phase delay values in order to control the phase of the demodulation signal in accordance with periodic changes of the incoming signal.

19. The electronic device of claim 18, wherein the electrodes to which the stimulation signal is sent by the driver circuit are row electrodes and the time specific phase delay values are row specific phase delay values.

20. The electronic device of claim 12, further comprising a plurality of analog channels, each analog channel receiving a respective incoming signal, the incoming signals of at least two of the analog channels having different phase, each analog channel comprising a respective demodulation circuit which generates a respective demodulation signal and controls its phase based on a respective channel specific phase delay value.

21. The electronic device of claim 20 wherein each demodulation circuit controls the phase of its respective demodulation signal based on a combination of a channel specific phase delay value and a plurality of row specific phase delay values.

22. The electronic device of claim 20, wherein the each demodulation circuit controls the phase of its respective demodulation signal based on one or more pixel specific phase delay values obtained from a table of pixel specific phase delay values, wherein each pixel specific phase delay value is associated with a desired phase delay for a particular row and channel combination.

23. The electronic device of claim 22, wherein the table of pixel specific phase delay values is held in RAM.

24. The electronic device of claim 12, wherein the electronic device is a mobile telephone.

25. The electronic device of claim 12, wherein the electronic device is a portable music player.

26. The electronic device of claim 12, wherein the analog channel further includes a mixer configured to mix the incoming signal with the demodulation signal.

27. A method for processing a signal comprising:

sending a stimulation signal across one or more traversal circuits;

modifying the stimulation signal by the one or more traversal circuits to form a first signal, the modification including at least a change in phase;

receiving the first signal at a processing module;

generating a demodulation signal by a demodulation circuit comprised by the processing module, the demodulation signal having the same phase as the first signal; and

processing the first signal with reference to the demodulation signal.

28. The method of claim 27, wherein the processing of the first signal with reference to the demodulation signal is performed by mixing the first signal and the demodulation signal.

29. The method of claim 28, wherein the mixing produces a signal selected from the group consisting of:

a demodulated version of the first signal, a rectified version of the first signal, a noise suppressed version of the first signal and a demodulated, rectified and noise suppressed version of the first signal.

30. The method of claim 27, the generating the demodulation signal is performed with reference to a processing module specific value associated with the phase of the first signal.

31. The method of claim 30, further including:

testing a plurality of versions of the processing module value;

discovering a version that results in a match to within predetermined limits of the phases of the demodulation signal and the first signal; and

saving the version as the processing module specific value.

32. The method of claim 28, further comprising:

changing the traversal circuits periodically so that the phase of the first signal changes periodically; and

changing the phase of the demodulation signal periodically by the demodulation circuit so that the phase of the demodulation signal matches the phase of the first signal.

33. The method of claim 32, wherein the changing of the phase of the demodulation signal periodically is performed by referring to one of a plurality of time specific values, the time specific values being associated with the periodic changes of the phase of the first signal, in combination with the processing module specific value.

34. A method for processing information on a sensor panel, the method comprising:

sending a stimulation signal to the panel;

receiving an incoming signal at an analog channel, the incoming signal being related to the stimulation signal, but having a different phase than the stimulation signal;

generating a demodulation signal at a demodulation circuit;

controlling the phase of the demodulation signal to ensure it matches that of the incoming signal; and

processing the incoming signal with reference to the demodulation signal.

35. The method of claim 34, wherein the processing of the incoming signal includes mixing the incoming signal with the demodulation signal at a mixer.

36. The method of claim 34, wherein the controlling the phase of the demodulation signal is performed by referring to a channel specific phase delay value associated with the phase of the incoming signal at the analog channel.

37. The method of claim 36, further including:

testing a plurality of versions of the channel specific phase delay value;

discovering a version that results in a match to within predetermined limits of the phases of the demodulation signal and the incoming signal; and

saving the version as the channel specific phase delay value.

38. The method of claim 34, wherein

sending a stimulation signal to the panel further comprises periodically sending the stimulation signal to different groups of one more electrodes the groups being selected from a plurality of electrodes of the panel;

said stimulation of different groups of electrodes results in periodic changes of the phase of the incoming signal, depending on which group is being stimulated; and

controlling the phase of the demodulation signal further includes periodically changing the phase of the demodulation signal to match the periodic changes of the phase of the incoming signal.

39. The method of claim 38, wherein the periodically changing the phase of the demodulation signal is performed by referring to a plurality of time specific phase delay values, each time specific phase delay value being associated with a phase of the incoming signal caused by the stimulation of a respective group of electrodes.

40. The method of claim 39, further including the step of interpolating an unknown time specific phase delay value from one or more known time specific phase delay values.

41. The method of claim 39, wherein the method is performed by a plurality of analog channels, each analog channel experiencing different phase delay at a given time, and the controlling the phase of the demodulation signal further includes referring to one of a plurality of channel specific phase delay values associated with the analog channel by which the method is performed.

42. The method of claim 41, further including the step of interpolating an unknown channel specific phase delay value from one or more known channels specific phase delay values.

43. The method of claim 39, further including:

testing a plurality of versions of each of the time specific phase delay value from the plurality of time specific phase delay values;

discovering a version for each respective time specific phase delay value that results in a match to within predetermined limits of the phases of the demodulation signal and the incoming signal; and

saving the discovered versions as the plurality of time specific phase delay values.

44. The method of claim 34, wherein the sensor panel is a multi touch panel.

45. The method of claim 34, wherein the sensor panel is a proximity sensor panel.

46. The method of claim 34, wherein the controlling the phase of the demodulation signal further comprises:

placing a digital representation of a single wave iteration of the demodulation signal in a shift register, having multiple tap points;

shifting the values within the shift register periodically, so that different values defining a digital representation of a demodulation wave appear at each tap point;

inserting values shifted out of one end of the shift register into the other end of the shift register; and

selecting one of the multiple tap points based on a desired phase of the demodulation signal.

47. A mobile telephone comprising:

a multi touch panel;

a driver circuit for sending a stimulation signal to the multi touch panel;

at least one analog channel for receiving an incoming signal from the multi touch panel, the incoming signal being related to the stimulation signal, the analog channel further comprising a demodulation circuit for generating a demodulation signal and controlling the phase of the demodulation signal so that it matches the phase of the incoming signal.

48. A portable music player comprising:

a multi touch panel;

a driver circuit for sending a stimulation signal to the multi touch panel;

at least one analog channel for receiving an incoming signal from the multi touch panel, the incoming signal being related to the stimulation signal, the analog channel further comprising a demodulation circuit for generating a demodulation signal and controlling the phase of the demodulation signal so that it matches the phase of the incoming signal.

49. A method for controlling the phase of a demodulation signal comprising:

placing a digital representation of at least part of the demodulation signal in a shift register including a plurality of tap points;

shifting the values within the shift register according to a phase clock, so that different values defining a digital representation of a demodulation wave appear at each tap point;

selecting a tap point as a source of a demodulation wave, the selection being based on a desired phase of the demodulation signal; and

changing the frequency of the clock in order to control the granularity of the digital representation of at least part of the demodulation signal as well as the size of the portion of the demodulation signal whose digital representation is placed in the shift register.

50. A method for initializing a plurality of desired phase delay values in an electronic device featuring a multi touch panel comprising a plurality of rows and a plurality of channels intersecting the rows, a stimulation circuitry for sending a stimulation signal to one or more of the rows, and analog channels for detecting signals from respective channels of the multi-touch panel, the method comprising performing the following steps for each row of the plurality of rows:

sending a stimulation signal to the row;

generating a demodulation signal by each analog channel;

sweeping the phase of each demodulation signal so that demodulation signals of plurality of different phases are generated by each analog channel;

detecting at each analog channel a plurality of results, each result being based on the stimulation signal and the demodulation signal applied at a particular time;

determining at each analog channel the highest result, and the phase of the demodulation signal associated with the highest result; and

saving the determined phase by each analog channel as a desired phase delay value associated with the combination of the row and the respective analog channel,

wherein the method results in plurality of desired phase delay values, which are usable during ordinary operation of the device to control the phase of the demodulation signal for each analog channel.

51. The method of claim 50, further including processing the plurality of desired phase delay values to obtain a decreased number of phase delay values, wherein said processing step is performed once for each initialization.

52. The method of claim 51, wherein the processing includes obtaining a plurality of row specific phase delay values and a plurality of channel specific phase delay values.