Focused capacitive sensing

Patent metadata

Field	Value
Publication number	US-10684728-B2
Application number	US-201515517135-A
Country	US
Kind code	B2
Filing date	Sep 16, 2015
Priority date	Oct 7, 2014
Publication date	Jun 16, 2020
Grant date	Jun 16, 2020

Abstract

Capacitive sensing can be used to measure electrostatic features of a space. Rudimentary capacitive sensing can be blurry. For instance, the resolution of a capacitive sensor generating a simple electric field is not very high, and the response to the simple electric field is also not very high. Using many capacitive sensors and special sets of excitation signals exciting the capacitive sensors, the capacitive sensors can generate specialized electrostatic fields. Because the specialized electrostatic fields provide different views of the space, enhanced inferences can be made from measurements of responses to those specialized electrostatic fields. Selecting certain specialized electrostatic fields can allow capacitive sensors to sense a focused region of the space. Repeating the steps with varied electrostatic fields can allow capacitive sensors to make enhanced inferences for many focused regions of the space, thereby increasing the resolution of capacitive sensing.

First claim

The invention claimed is:

1. A method for focused capacitive sensing of a space using capacitive sensors, the method comprising:
exciting the capacitive sensors using a first set of aperiodic excitation signals to generate a first electrostatic field, wherein the first set of aperiodic excitation signals excite some capacitive sensor(s) to have an on average positive polarity and some capacitive sensor(s) to have an on average negative polarity;
taking a first measurement using the capacitive sensors to capacitively sense a first response of the space to the first electrostatic field;
exciting the capacitive sensors using a second set of aperiodic excitation signals different from the first set of aperiodic excitation signals to generate a second electrostatic field different from the first electrostatic field, wherein the second set of aperiodic excitation signals excite some capacitive sensor(s) to have an on average positive polarity and some capacitive sensor(s) to have an on average negative polarity; and
taking a second measurement using the capacitive sensors to capacitively sense a second response of the space to the second electrostatic field;
wherein, at least two adjacent capacitive sensors are excited to have the same on average polarity.

2. A method for focused capacitive sensing of a space using capacitive sensors, the method comprising:
signaling to an excitation source to excite the capacitive sensors using a first set of aperiodic excitation signals to generate a first electrostatic field, wherein the first set of aperiodic excitation signals excite some capacitive sensor(s) to have a positive polarity and some capacitive sensor(s) to have a negative polarity;
receiving a first measurement taken by the capacitive sensors to capacitively sense a first response of the space to the first electrostatic field;
signaling to the excitation source to excite the capacitive sensors using a second set of aperiodic excitation signals to generate a second electrostatic field different from the first electrostatic field, wherein the second set of aperiodic excitation signals excite some capacitive sensor(s) to have a positive polarity and some capacitive sensor(s) to have a negative polarity; and
receiving a second measurement taken by the capacitive sensors to capacitively sense a second response of the space to the second electrostatic field;
wherein, at least two adjacent capacitive sensors are signaled to have the same polarity.

3. The method of claim 2 , the method further comprising:
deriving one or more features of the space based on the first measurement and the second measurement.

4. The method of claim 2 , the method further comprising:
repeating the signaling and receiving steps for a plurality of other electrostatic fields generated by the capacitive sensors using other sets of excitation signals; and
deriving one or more features of the space based on further measurements from the repeated receiving step.

5. The method of claim 3 , wherein the one or more features of the space corresponds to a first region in the space.

6. The method of claim 3 , wherein the one or more features of the space corresponds to a first region in the space and a second region in the space.

7. The method of claim 3 , wherein the one or more features of the space corresponds to one or more dielectric constants of one or more regions in the space.

8. The method of claim 3 , wherein deriving one or more features of the space comprises:
performing inference based on a model of different features of the space using at least the first measurement and the second measurement.

9. The method of claim 3 , wherein deriving one or more features of the space comprises:
applying belief propagation using at least the first measurement and the second measurement to infer the one or more features of the space.

10. The method of claim 3 , wherein performing inference comprises applying Markov random fields processing using at least the first measurement and the second measurement to infer the one or more features of the space.

11. The method of claim 3 , wherein performing inference comprises applying Bayesian network processing using at least the first measurement and the second measurement to infer the one or more features of the space.

12. The method of claim 3 , wherein the one or more features of the space corresponds to one or more values of an image representative of the space.

13. The method of claim 3 , wherein the one or more features of the space corresponds to one or more densities of regions in the space.

14. The method of claim 3 , wherein the one or more features of the space corresponds to one or more characteristics of materials or surfaces present in the space.

15. The method of claim 3 , further comprising:
determining a third set of aperiodic excitation signals based on the first measurement, wherein the third set of aperiodic excitation signals excite some capacitive sensor(s) to have a positive polarity and some capacitive sensor(s) to have a negative polarity;
signaling to the excitation source to excite the capacitive sensors using the third set of aperiodic excitation signals to generate a third electrostatic field different from the first electrostatic field; and
receiving a third measurement taken by the capacitive sensors to capacitively sense a third response of the space to the third electrostatic field.

16. An apparatus for focused capacitive sensing of a space using capacitive sensors, the apparatus comprising:
an excitation source to excite the capacitive sensors using a different sets of aperiodic excitation signals to generate different electrostatic fields, wherein the sets of aperiodic excitation signals excite some capacitive sensor(s) to have an on average positive polarity and some capacitive sensor(s) to have an on average negative polarity; and
a sampling circuit to take measurements using the capacitive sensors to capacitively sense responses of the space to the different electrostatic fields;
wherein, the excitation source is configured to excite at least two adjacent capacitive sensors to have the same on average polarity.

17. The apparatus of claim 16 , wherein:
the excitation source excites a first subset of the capacitive sensors; and
the sampling circuit takes measurements using a second subset of the capacitive sensors different from the first subset of the capacitive sensors.

18. The apparatus of claim 16 , wherein:
at least some of the capacitive sensors are physically arranged according to one or more of the following spatial arrangements: a linear array, a grid comprising row(s) and column(s), circular arrangement, elliptical arrangement, curved arrangement, random arrangement, fractal arrangement, symmetrical arrangement, and geometric pattern.

19. The apparatus of claim 16 , wherein:
at least some of the capacitive sensors are movable an actuator to different spatial arrangements to generate different electrostatic fields and/or take measurements in response to the different electrostatic fields.

20. The apparatus of claim 16 , wherein:
at least some of the capacitive sensors are movable by an actuator to different spatial arrangements according to one or more of the following: a predetermined sequence of spatial arrangements, a randomized sequence of spatial arrangements, a sequence of spatial arrangements determined based on previous measurements.

Assignees

• Analog Devices Inc

Inventors

• Wingate David

Classifications

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/041661 Primary

  using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window · CPC title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title