Injected touch noise analysis

• US 9,547,399 B2
• Filed: 10/27/2014
• Issued: 01/17/2017
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Parade Technologies, Ltd.
• Inventors: Olson, Dana, Maharyta, Andriy, Kolokowsky, Steve
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US14/525,025
• Publication Number:
  US 20150199046A1
• Time in Patent Office: 813 Days
• Field of Search: 702/69, 345/173, 345/174
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04809 Textured surface identifying touch areas, e.g. overlay structure for a virtual keyboard
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• 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 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe

Abstract

A processing device configured to induce, during a listening scan of a sense array, an injected touch to produce similar data as would be present during a touch scan of the sense array with a conductive object at a known location on the sense array. The processing device is further configured to compute, using the data, an estimate of a noise metric based on the injected touch.

Claims

1. A method of detecting a touch proximate to a touch sensing surface, comprising:

at a processing device coupled to the touch sensing surface, wherein the touch sensing surface includes a capacitive sense array that is configured to generate touch data associated with the detected touch, and the processing device is configured to operate a scanning sequence including a listening scan and a touch scan of the capacitive sense array;

measuring noise during the listening scan, including;

disabling stimulus signals that drive the capacitive sense array; and

simulating a touch event by inducing a surrogate touch current in the processing device to produce data that mimics the touch scan with a conductive object disposed at a known location on the capacitive sense array;

computing, using the produced data, an estimate of a noise metric based on the injected touch;

in accordance with the computed estimate of the noise metric, selecting a stimulus signal from a plurality of stimulus signals for the touch scan; and

while driving the capacitive sensing array with the selected stimulus signal, collecting touch data indicative of the touch detected proximate to the capacitive sense array during the touch scan of the capacitive sense array.

2. The method of claim 1, wherein the known location comprises one or more cells of a plurality of cells of the capacitive sense array where the detected touch proximate to the sense array occurs.

3. The method of claim 1, wherein measuring noise during the listening scan further includes measuring the noise in accordance with a plurality of frequencies, and the estimate of the noise metric is computed in accordance with the plurality of frequencies.

4. The method of claim 3, wherein the noise is measured for the plurality of frequencies in parallel.

5. The method of claim 1, wherein simulating the touch event comprises inducing an injected touch internal to a receiving circuit, and wherein the produced data of the touch event is processed in an equivalent signal path to touch data from a touch proximate to the sense array present during the touch scan of the sense array.

6. The method of claim 5, wherein the receiving circuit is used in a capacitance-sensing circuit.

7. The method of claim 1, wherein the noise metric is indicative of noise characteristics of noise on the sense array.

8. The method of claim 7, wherein the selected stimulus signal has a minimum noise response.

9. An apparatus, comprising

a processing device coupled to a touch sensing surface, wherein the touch sensing surface includes a capacitive sense array that is configured to generate touch data associated with a touch proximate to the touch sensing surface, and the processing device is configured to:

operate a scanning sequence including a listening scan and a touch scan of the capacitive sense array;

measure noise during the listening scan, including;

disabling stimulus signals that drive the capacitive sense array; and

simulating a touch event by inducing a surrogate touch current in the processing device to produce data that mimics the touch scan with a conductive object disposed at a known location on the capacitive sense array;

compute, using the produced data, an estimate of a noise metric based on the injected touch;

in accordance with the computed estimate of the noise metric, selecting a stimulus signal from a plurality of stimulus signals for the touch scan; and

while driving the capacitive sensing array with the selected stimulus signal, collecting touch data indicative of the touch detected proximate to the capacitive sense array during the touch scan of the capacitive sense array.

10. The apparatus of claim 9, wherein the known location comprises one or more cells of a plurality of cells of the capacitive sense array where the detected touch proximate to the sense array occurs.

11. The apparatus of claim 9, wherein measuring noise during the listening scan, further includes measuring the noise for a plurality of frequencies, and the estimate of the noise metric is computed in accordance with the plurality of frequencies.

12. The apparatus of claim 11, wherein during the listening scan, the noise is measured for the plurality of frequencies in parallel.

13. The apparatus of claim 9, wherein the processing device is further configured to induce an injected touch internal to a receiving circuit, and wherein the processing device is further configured to process the produced data of the touch event in an equivalent signal path to touch data from a touch proximate to the sense array present during the touch scan of the sense array.

14. The apparatus of claim 13, wherein the receiving circuit is used in a capacitance-sensing circuit.

15. The apparatus of claim 9, wherein the noise metric is indicative of noise characteristics of noise on the sense array.

16. The apparatus of claim 15, wherein the selected stimulus signal has a minimum noise response.

17. An electronic system, comprising:

a capacitive sense array configured to generate touch data for a touch detected proximate to the capacitive sense array, the touch data represented as a plurality of cells; and

a processing device coupled to the capacitive sense array, wherein the processing device is configured to;

operate a scanning sequence including a listening scan and a touch scan of the capacitive sense array;

measure noise during the listening scan, including;

disabling stimulus signals that drive the capacitive sense array; and

simulating a touch event by inducing a surrogate touch current in the processing device to produce data that mimics the touch scan with a conductive object disposed at a known location on the capacitive sense array;

compute, using the produced data, an estimate of a noise metric based on the injected touch;

in accordance with the computed estimate of the noise metric, selecting a stimulus signal from a plurality of stimulus signals for the touch scan; and

while driving the capacitive sensing array with the selected stimulus signal, collecting touch data indicative of the touch detected proximate to the capacitive sense array during the touch scan of the capacitive sense array.

18. The electronic system of claim 17, wherein the processing device is further configured to induce an injected touch internal to a receiving circuit, and wherein the processing device is further configured to process the produced data of the touch event in an equivalent signal path to touch data from a touch proximate to the sense array present during the touch scan of the sense array.

19. The electronic system of claim 17, wherein measuring noise during the listening scan includes measuring the noise in accordance with a plurality of frequencies, and the estimate of the noise metric is computed in accordance with the plurality of frequencies.

20. The electronic system of claim 19, wherein during the listening scan, the noise is measured for the plurality of frequencies in parallel.