Capacitive body proximity sensor system
View Patent ↗Described herein are systems, methods and apparatuses that can detect the proximity of an object and differentiate between a human body and a non-human object. The detection and differentiation are facilitated by a first capacitive sensor of a first shape and a second capacitive sensor of a second shape. The detection and determination can be made based on a comparison between a first capacitance from the first sensor and a second capacitance from the second sensor.
1. A system, comprising:
a first sensor having a first shape, wherein the first sensor detects a first capacitance related to an object located at a specified non-zero distance from the first sensor;
a second sensor having a second shape different from the first shape, wherein the second sensor detects a second capacitance related to the object, wherein the first sensor and the second sensor are concentric, and the second sensor fully encircles the first sensor, and wherein a first size of the first sensor and a second size of the second sensor are adapted based on a third size of the object and a distance detection criterion;
an electronic component, operatively arranged for measuring the capacitances of the first sensor and the second sensor in a multiplexed manner, that performs a mathematical operation that employs the first capacitance and the second capacitance to generate an output, wherein the output facilitates discrimination of whether the object is a human body or a non-human object based on capacitance profiles associated with different dielectric properties of the human body and the non-human object; and
an active bias shield comprising an active bias driver that tracks respective voltages on the first sensor and the second sensor, wherein the active bias shield is configured to provide sensing directionality associated with detection of the object.
2. The system of claim 1 , wherein
the first sensor has a first area and a first perimeter, and wherein
the second sensor has a second area and a second perimeter, and further wherein
the first area is different from the second area.
3. The system of claim 1 , wherein
the first sensor has a first area and a first perimeter, and wherein
the second sensor has a second area and a second perimeter, and further wherein
the first perimeter is different from the second perimeter.
4. The system of claim 1 , wherein the electronic component determines a sum of the first capacitance and the second capacitance to facilitate the discrimination.
5. The system of claim 1 , wherein the electronic component determines a difference between the first capacitance and the second capacitance to facilitate the discrimination.
6. The system of claim 1 , further comprising a radiation source that limits electromagnetic radiation power or exposure time from the radiation source in response to a determination, based on the first capacitance and the second capacitance, that the object is the human body.
7. The system of claim 1 , wherein the first sensor and the second sensor are configured in a partially symmetrical arrangement or in a fully-symmetrical arrangement.
8. The system of claim 1 , wherein the first sensor comprises a first conductive material and the second sensor comprises of a second conductive material.
9. The system of claim 1 , wherein the electronic component comprises a time-multiplexed capacitance-to-digital converter.
10. The system of claim 1 , further comprising a radiation source that modifies an emission of radiation in response to a determination, based on the first capacitance and the second capacitance, that the object is the human body.
11. A method, comprising:
processing a first signal indicative of a first capacitance from a first sensor having a first shape;
processing a second signal indicative of a second capacitance from a second sensor having a second shape that encircles the first shape, wherein the first capacitance and the second capacitance are acquired in a multiplexed fashion, and wherein a first size of the first sensor and a second size of the second sensor are selected based on a third size of an object that is to be detected and a distance detection criterion associated with a non-zero distance between the object and at least one of the first sensor or the second sensor;
determining a type of the object of a set of objects having different dielectric properties that is in proximity of the first sensor and the second sensor based on capacitance profile data associated with the different dielectric properties of the set of objects;
tracking, by an active bias driver, respective voltages on the first sensor and the second sensor; and
based on the respective voltages, configuring sensing directionality associated with detection of the object.
12. The method of claim 11 , wherein
the first sensor has a first area and a first perimeter, and wherein
the second sensor has a second area and a second perimeter, and further wherein
the first area is different from the second area.
13. The method of claim 11 , wherein
the first sensor has a first area and a first perimeter, and wherein
the second sensor has a second area and a second perimeter, and further wherein
the first perimeter is different from the second perimeter.
14. The method of claim 11 , wherein the determining further comprises calculating a difference between the first capacitance and the second capacitance, and determining the type of object based on the difference.
15. The method of claim 11 , wherein the determining comprises determining that the object is a human body and the method further comprises:
in response to the determining, instructing a controller device to reduce a radio-frequency (RF) electromagnetic field (EMF) emission.
16. An apparatus, comprising:
a first sensor that detects a first capacitance;
a second sensor that detects a second capacitance, the second sensor is concentric with and fully encircles the first sensor, wherein a first size of the first sensor and a second size of the second sensor are selected based on a third size of an object to be detected and a distance detection criterion associated with a non-zero distance between the object and at least one of the first sensor or the second sensor;
an electronic component configured to measure the first capacitance and the second capacitance in a multiplexed manner, and configured to generate an output based on a mathematical operation that employs the first capacitance and the second capacitance, wherein the output is employed to determine that the object in proximity of the apparatus is a human body based on a capacitance profile associated with a dielectric property of the human body; and
an active bias shield comprising an active bias driver configured to track respective voltages on the first sensor and the second sensor, wherein the respective voltages are employed to provide sensing directionality associated with detection of the object.
17. The apparatus of claim 16 , further comprising a radiation emitter that reduces emitted radiation in response to the determination that the object in proximity to the apparatus is the human body.
18. The apparatus of claim 16 , wherein the electronic component processes a first time-dependent profile of the first capacitance and a second time-dependent profile of the second capacitance to facilitate the determination of whether the object in proximity of the apparatus is the human body or a non-human object.