METHODS AND APPARATUS FOR A CAPACITIVE SENSOR
Various embodiments of the present technology may provide methods and apparatus for a capacitive sensor. The capacitive sensor may include two sensor pads that have overlapping electric fields and operate independent from each other. The capacitive sensor may also include a ground electrode positioned adjacent to the sensor pads.
1 . A mutual capacitance proximity sensor, comprising:
a first sensor pad comprising a first electrode capable of forming a first electric field with a second electrode;
a second sensor pad positioned adjacent to the first sensor pad and comprising a third electrode capable of forming a second electric field with a fourth electrode; wherein a first portion of the first electric field overlaps with a second portion of the second electric field; and
a fifth electrode positioned adjacent to the first and second sensor pads, wherein the fifth electrode is configured to change a distribution of:
the first portion of the first electric field; and
the second portion of the second electric field.
2 . The mutual capacitance proximity sensor according to claim 1 , wherein the fifth electrode has a voltage potential that is between zero volts and one-half of a supply voltage.
3 . The mutual capacitance proximity sensor according to claim 1 , wherein the fifth electrode maintains a ground potential.
4 . The mutual capacitance proximity sensor according to claim 1 , wherein the first and second sensor pads are formed on a first surface of a single, continuous substrate.
5 . The mutual capacitance proximity sensor according to claim 4 , wherein the fifth electrode is formed on the first surface of the single, continuous substrate and positioned directly between the first and second sensor pads.
6 . The mutual capacitance proximity sensor according to claim 4 , wherein the fifth electrode is formed on a second surface of the substrate, wherein the second surface is opposite from and in parallel with the first surface.
7 . The mutual capacitance proximity sensor according to claim 1 , wherein the first and second sensor pads and the fifth electrode are each formed on separate and distinct substrates.
8 . A method for detecting an object using a mutual capacitance proximity sensor, comprising:
forming a first electric field between a first electrode and a second electrode;
forming a second electric field between a third electrode and a fourth electrode;
forming an overlapping region of electric fields;
changing a distribution of the electric fields in the overlapping region;
measuring a change in the first electric field;
measuring a change in the second electric field; and
determining a presence of the object based on the measured change in at least one of the first and second electric fields.
9 . The method according to claim 8 , wherein the overlapping region of electric fields comprises a first portion of the first electric field that overlaps a second portion of the second electric field.
10 . The method according to claim 8 , wherein changing the electric fields in the overlapping region comprises providing a ground electrode in the overlapping region.
11 . A proximity sensor system, comprising:
a capacitive sensor comprising:
a first sensor pad capable of generating a first electric field;
a second sensor pad positioned adjacent to the first sensor pad and capable of generating a second electric field;
a fifth electrode positioned adjacent to the first and second sensor pads, wherein the fifth electrode is configured to change a distribution of:
a first portion of the first electric field; and
a second portion of the second electric field;
a sensing circuit connected to the capacitive sensor and configured to measure a change in the first and second electric fields; and
a microcontroller connected to the sensing circuit and configured to generate a control signal according to the measured change in the first and second electric fields.
12 . The proximity sensor system according to claim 11 , wherein:
the first sensor pad comprises a first electrode in communication with a second electrode; and
the second sensor pad comprises a third electrode in communication with a fourth electrode.
13 . The proximity sensor system according to claim 11 , wherein the sensing circuit is configured to receive a supply voltage.
14 . The proximity sensor system according to claim 11 , wherein the fifth electrode has a voltage potential that is between zero volts and one-half of the supply voltage.
15 . The proximity sensor system according to claim 11 , wherein the fifth electrode maintains a ground potential.
16 . The proximity sensor system according to claim 11 , wherein the first and second sensor pads are formed on a first surface of a single, continuous substrate.
17 . The proximity sensor according to claim 16 , wherein the fifth electrode is formed on the first surface of the single, continuous substrate and is positioned directly between the first and second sensor pads.
18 . The proximity sensor according to claim 16 , wherein the fifth electrode is formed on a second surface of the substrate, wherein the second surface is opposite from and in parallel with the first surface.
19 . The proximity sensor system according to claim 11 , wherein the first and second sensor pads are formed on separate and distinct substrates.
20 . The proximity sensor system according to claim 11 , wherein the first portion of the first electric field overlaps with the second portion of the second electric field.