OVERSAMPLED STEP AND WAIT SYSTEM FOR CAPACITIVE SENSING

• US 20170090609A1
• Filed: 09/25/2015
• Published: 03/30/2017
• Est. Priority Date: 09/25/2015
• Status: Abandoned Application

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: PETROVIC, Vladan, SOBEL, David
• Application Number:
  US14/866,142
• Publication Number:
  US 20170090609A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

Embodiments described herein include a method, input device, and processing system for capacitive sensing. The input device comprises a plurality of transmitter electrodes and a plurality of receiver electrodes. The method comprises transmitting, on one or more of the plurality of transmitter electrodes, a capacitive sensing signal comprising a plurality of sensing half-cycles. The method further comprises sampling, two or more times during each sensing half-cycle, effects of the transmitted capacitive sensing signal on one or more of the plurality of receiver electrodes to produce half-cycle sensing data, filtering the half-cycle sensing data, and determining positional information for an input object using the filtered half-cycle sensing data.

Claims

1. A method of capacitive sensing using an input device comprising a plurality of transmitter electrodes and a plurality of receiver electrodes, the method comprising:

transmitting, on one or more of the plurality of transmitter electrodes, a capacitive sensing signal comprising a plurality of sensing half-cycles;

sampling, two or more times during each sensing half-cycle, effects of the transmitted capacitive sensing signal on one or more of the plurality of receiver electrodes to produce half-cycle sensing data;

filtering the half-cycle sensing data; and

determining positional information for an input object using the filtered half-cycle sensing data.

2. The method of claim 1, wherein filtering the half-cycle sensing data comprises a weighted averaging of the sampled effects of the half-cycle sensing data.

3. The method of claim 1, wherein each of the plurality of sensing half-cycles comprises a respective integration period and a respective stretch period, wherein sampling the effects of the transmitted capacitive sensing signal is performed during each integration period.

4. The method of claim 3, wherein the capacitive sensing signal is transmitted in at least first and second bursts, wherein each burst includes a respective plurality of sensing half-cycles, wherein the sensing half-cycles of the first burst have a stretch period of a first length, and wherein the sensing half-cycles of the second burst have a stretch period of a second length different from the first length.

5. The method of claim 3, further comprising:

updating, during each integration period, an integration count reflecting charge that is measured during the integration period, wherein the sampled effects correspond to the integration count;

resetting, during each stretch period, the integration count to a predetermined value; and

applying a reset correction value to the half-cycle sensing data prior to filtering the half-cycle sensing data.

6. The method of claim 1, comprising performing absolute capacitive sensing techniques to obtain the sampled effects of the transmitted capacitive sensing signal.

7. The method of claim 1, comprising performing transcapacitive sensing techniques to obtain the sampled effects of the transmitted capacitive sensing signal.

8. The method of claim 1, wherein the filter applied to the half-cycle sensing data is a digital windowing filter.

9. An input device, comprising:

a plurality of transmitter electrodes;

a plurality of receiver electrodes; and

a processing system coupled with the plurality of transmitter electrodes and the plurality of receiver electrodes, and comprising circuitry configured to;

transmit, on one or more of the plurality of transmitter electrodes, a capacitive sensing signal comprising a plurality of sensing half-cycles;

sample, two or more times during each sensing half-cycle, effects of the transmitted capacitive sensing signal on one or more of the plurality of receiver electrodes to produce half-cycle sensing data;

filtering the half-cycle sensing data; and

determine positional information for an input object using the filtered half-cycle sensing data.

10. The input device of claim 9, wherein filtering the half-cycle sensing data comprises a weighted averaging of the sampled effects of the half-cycle sensing data.

11. The input device of claim 9, wherein the processing system is configured to:

transmit the capacitive sensing signal with each of the plurality of sensing half-cycles comprising a respective integration period and a respective stretch period, and

sample the effects of the transmitted capacitive sensing signal during each integration period.

12. The input device of claim 11, wherein the capacitive sensing signal is transmitted in at least first and second bursts, wherein each burst includes a respective plurality of sensing half-cycles, wherein the sensing half-cycles of the first burst have a stretch period of a first length, and wherein the sensing half-cycles of the second burst have a stretch period of a second length different from the first length.

13. The input device of claim 11, wherein the processing system comprises a charge integrator having a reset switch, and wherein the processing system is further configured to:

update, using the charge integrator and during each integration period, an integration count reflecting charge that is measured during the integration period, wherein the sampled effects correspond to the integration count;

close, during each stretch period, the reset switch to reset the integration count to a predetermined value; and

apply a reset correction value to the half-cycle sensing data prior to filtering the half-cycle sensing data.

14. The input device of claim 9, wherein the processing system is configured to perform absolute capacitive sensing techniques to obtain the sampled effects of the transmitted capacitive sensing signal.

15. The input device of claim 9, wherein the processing system is configured to perform transcapacitive sensing techniques to obtain the sampled effects of the transmitted capacitive sensing signal.

16. The input device of claim 9, wherein the processing system comprises a digital windowing filter configured to filter the half-cycle sensing data.

17. A processing system for capacitive sensing, comprising:

touch controller circuitry configured to;

couple with a plurality of transmitter electrodes and a plurality of receiver electrodes;

transmit, on one or more of the plurality of transmitter electrodes, a capacitive sensing signal comprising a plurality of sensing half-cycles;

sample, two or more times during each sensing half-cycle, effects of the transmitted capacitive sensing signal on one or more of the plurality of receiver electrodes to produce half-cycle sensing data;

filtering the half-cycle sensing data; and

determine positional information for an input object using the filtered half-cycle sensing data.

18. The processing system of claim 17, wherein the touch controller circuitry is configured to:

transmit the capacitive sensing signal with each of the plurality of sensing half-cycles comprising a respective integration period and a respective stretch period, and

sample the effects of the transmitted capacitive sensing signal during each integration period.

19. The processing system of claim 18, wherein the touch controller circuitry further comprises a charge integrator having a reset switch, and wherein the touch controller circuitry is further configured to:

update, using the charge integrator and during each integration period, an integration count reflecting charge that is measured during the integration period, wherein the sampled effects correspond to the integration count;

close, during each stretch period, the reset switch to reset the integration count to a predetermined value; and

apply a reset correction value to the half-cycle sensing data prior to filtering the half-cycle sensing data.

20. The processing system of claim 17, wherein the touch controller circuitry further comprises a digital windowing filter configured to filter the half-cycle sensing data.