EMI resistant balanced touch sensor and method
First Claim
1. A low impedance, EMI resistant touch sensor apparatus for detecting human, metal or liquid contact and capable of activating a controlled device, said touch sensor apparatus comprising:
- a dielectric substrate having first and second opposing surfaces;
a first conductive electrode pad disposed on said first surface of said substrate in a continuous form defining a selected pad surface area of conductive material;
a second conductive electrode disposed on said first surface of said substrate in a spaced, coplanar and substantially surrounding relationship to said first electrode pad, and defining a selected surface area of conductive material;
wherein said first electrode pad surface area is substantially equal to said second electrode surface area; and
an active electrical component disposed on said substrate proximate said first and second electrodes and electrically coupled to said first and second electrodes, such that human, metal or liquid contact with said substrate activates the controlled device.
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Accused Products
Abstract
An EMI resistant, low impedance touch sensor detects contact of a dielectric substrate by an operator'"'"'s appendage or body part, a metal object, or the proximity of a moving fluid/gas interface. The touch sensor includes a first conductive electrode pad and a second conductive electrode of substantially equal area which is spaced from the first electrode by a channel of non-conductive dielectric. The first and second electrodes are optionally disposed on the same surface of the substrate. An active electrical component including an oscillator and a differential sensing circuit is located on the substrate proximate the first and second electrodes and is electrically coupled to the first and second electrodes. Noise or interference signals appearing on both the first and second electrodes, being of substantially equal area, are subtracted from one another through to provide common mode rejection of EMI.
84 Citations
26 Claims
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1. A low impedance, EMI resistant touch sensor apparatus for detecting human, metal or liquid contact and capable of activating a controlled device, said touch sensor apparatus comprising:
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a dielectric substrate having first and second opposing surfaces;
a first conductive electrode pad disposed on said first surface of said substrate in a continuous form defining a selected pad surface area of conductive material;
a second conductive electrode disposed on said first surface of said substrate in a spaced, coplanar and substantially surrounding relationship to said first electrode pad, and defining a selected surface area of conductive material;
wherein said first electrode pad surface area is substantially equal to said second electrode surface area; and
an active electrical component disposed on said substrate proximate said first and second electrodes and electrically coupled to said first and second electrodes, such that human, metal or liquid contact with said substrate activates the controlled device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A low impedance, EMI resistant touch sensor apparatus for detecting contact by a human or contact by metal or a liquid and capable of activating a controlled device, said touch sensor apparatus comprising:
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a dielectric substrate having first and second opposite surfaces;
a first conductive electrode pad disposed on said substrate in a closed, continuous form having a selected conductive surface area to provide a region of contact;
a second conductive electrode disposed on said carrier in a spaced relationship to said first electrode and defining a selected second electrode conductive surface area;
wherein said first electrode'"'"'s conductive surface area is substantially equal to said second electrode'"'"'s conductive surface area;
an active electrical component disposed on said carrier proximate said first and second electrodes and electrically coupled to said first and second electrodes; and
such that human, metal or liquid contact with said substrate activates the controlled device. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A sensor for detecting a human being'"'"'s touch and capable of generating a control input detected signal for activating a controlled device, said sensor comprising:
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a dielectric substrate of substantially uniform thickness having first and second opposite surfaces;
a first conductive electrode pad covering a selected area on said first surface of said substrate in a closed, continuous form having an area which affords substantial coverage for human contact with said substrate second surface;
a second conductive electrode covering a selected area on said first surface of said substrate in a spaced and substantially surrounding relationship to said first electrode pad;
an active electrical component disposed on said substrate proximate said first and second electrodes and electrically coupled to said first and second electrodes, such that human contact with said substrate second surface activates the controlled device;
wherein said first thin, conductive electrode pad disposed on said first surface of said substrate comprises a balanced pad electrode having a surface area that is substantially equal with the surface area of said second conductive electrode. - View Dependent Claims (18, 19, 20)
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21. A sensor for detecting a human being'"'"'s touch and capable of generating a control input detected signal for activating a controlled device, said sensor comprising:
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a dielectric substrate of substantially uniform thickness having first and second opposite surfaces;
a first conductive electrode pad covering a selected area on said first surface of said substrate in a closed, continuous form having an area which affords substantial coverage for human contact with said substrate second surface;
a second conductive electrode covering a selected area on said second surface of said substrate in a spaced and substantially surrounding relationship to said first electrode pad, when seen in plan view;
an active electrical component disposed on said substrate proximate said first and second electrodes and electrically coupled to said first and second electrodes, such that human contact with said substrate second surface activates the controlled device;
wherein said first conductive electrode pad comprises a balanced pad electrode having a surface area that is substantially equal with the surface area of said second conductive electrode. - View Dependent Claims (22, 23, 24, 25)
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26. A method for processing touch sensor field effect signals, comprising:
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(a) providing a dielectric substrate;
(b) providing a first conductive electrode pad covering a selected surface area on said substrate in a closed, continuous geometric form;
(c) providing a second conductive electrode pad covering a selected surface area on said substrate in a spaced relationship to said first electrode pad;
wherein said first conductive electrode pad has a surface area that is substantially equal with the surface area of said second conductive electrode;
(d) generating an arc-shaped electric field between said first electrode and said second electrode;
(e) sensing changes in said electric field;
(f) sensing spurious or EMI signals on said first electrode and said second electrode; and
(g) rejecting said spurious or EMI signals when said spurious or EMI signals appear on both of said first and second electrodes.
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Specification