Neutralizing electromagentic noise for a capacitive input device

• US 8,121,806 B2
• Filed: 12/16/2009
• Issued: 02/21/2012
• Est. Priority Date: 11/28/2005
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP (Singapore) PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Mahowald, Peter H., Elsheimer, Robert, Misek, Brian J., Thelen, Robert M., Deitz, Zachary T.
• Primary Examiner(s): Nghiem, Michael
• Assistant Examiner(s): Ngon, Ricky
• Application Number:
  US12/639,323
• Publication Number:
  US 20100188362A1
• Time in Patent Office: 797 Days
• Field of Search: 345173-176, 345/178, 178/18.06, 178/19.03, 375130-153, 375219-223, 375/224, 375/227, 375/242, 375/254, 375/244, 375/354, 324/686, 324612-613, 324/658, 702/104, 702/127, 702/69, 702/57, 702/33, 702/38
• US Class Current: 702/104
• CPC Class Codes: G06F 3/03548 Sliders, in which the moving part moves in a plane
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation

Abstract

A method of capturing user control inputs for an electronic device comprises sampling an input measurement signal at a capacitive input sensor of the electronic device to capture user control inputs for operating the electronic device. Electromagnetic interference affecting the sampling or the input measurement signal is electronically neutralized.

Claims

1. A method of capturing user control inputs for an electronic device, comprising:

sampling a measurement signal at a capacitive input sensor of the electronic device to capture user control inputs for operating the electronic device; and

neutralizing an electromagnetic noise with the measurement signal adjacent the time the measurement signal is sampled,

wherein the electromagnetic noise comprises a pulsed radiofrequency signal emitted by the electronic device and neutralizing the electromagnetic noise comprises synchronizing sampling the measurement signal with pulses of the pulsed radiofrequency signal, the synchronizing sampling comprising sampling the measurement signal only during pulses of the pulsed radiofrequency signal and in between the pulses of the pulsed radiofrequency signal.

2. The method of claim 1, wherein the electromagnetic noise comprises ambient electromagnetic noise coupled to the capacitive input sensor and neutralizing the electromagnetic noise further comprises providing a parallel capacitive structure arranged in a mirrored orientation adjacent to the capacitive input sensor to enable sampling the measurement signal via differential signaling.

3. The method of claim 1, wherein the electromagnetic noise comprises ambient electromagnetic noise coupled to the capacitive input sensor and neutralizing the electromagnetic noise further comprises substantially randomly varying the sampling of the measurement signal via at least one of:

randomly varying a frequency of the sampling of the measurement signal; and

introducing random time delays in the sampling the measurement signal.

4. A method of capturing user control inputs for an electronic device, comprising:

sampling, within a presence of a pulsed radiofrequency signal, a position measurement signal at a capacitive position sensor of the electronic device to capture user control inputs for operating the electronic device; and

synchronizing the sampling of the position measurement signal relative to individual pulses of the pulsed radiofrequency signal;

wherein synchronizing the sampling of the position measurement signal comprises sampling the position measurement signal only during pulses of the pulsed radiofrequency signal and in between the pulses of the pulsed radiofrequency signal.

5. The method of claim 4, wherein synchronizing the sampling comprises tracking the pulsed radiofrequency pulses via an antenna associated with the capacitive position sensor.

6. The method of claim 4, wherein the electronic device comprises a wireless mobile phone and the pulsed radiofrequency signal is transmitted according to a time domain communication access protocol.

7. A method of capturing user control inputs for an electronic device, comprising:

sampling, within a presence of a pulsed radiofrequency signal, a position measurement signal at a capacitive position sensor of the electronic device to capture user control inputs for operating the electronic device; and

synchronizing the sampling of the position measurement signal relative to individual pulses of the pulsed radiofrequency signal;

wherein synchronizing the sampling of the position measurement signal comprises sampling the position measurement signal only in between adjacent pulses of the pulsed radiofrequency signal.

8. A method of capturing user control inputs for an electronic device, comprising:

sampling, within a presence of a pulsed radiofrequency signal, a position measurement signal at a capacitive position sensor of the electronic device to capture user control inputs for operating the electronic device;

synchronizing the sampling of the position measurement signal relative to individual pulses of the pulsed radiofrequency signal; and

wirelessly transmitting the pulsed radiofrequency signal from a radiofrequency transceiver of the electronic device; and

wherein synchronizing the sampling comprises providing an electronic communication link between the radiofrequency transceiver and the capacitive position sensor to enable the radiofrequency transceiver to control the synchronizing of the sampling of the position measurement signal.