Proximity sensor
First Claim
1. A capacitive sensor for detecting the presence of an object in a sensing region comprising:
- a ground plane;
a first insulating layer disposed on said ground plane;
a guard layer disposed on said first insulating layer;
a second insulating layer disposed on said guard layer;
a touch plate disposed on said second insulating layer;
an oscillator means for supplying an excitation signal to said touch plate; and
a driving means for supplying an excitation signal to said guard layer such that the capacitance between said guard layer and said ground plane substantially cancels the capacitance between said touch plate and said ground plane.
4 Assignments
0 Petitions
Accused Products
Abstract
An improved capacitive sensor for detecting the presence of objects in a sensing region. The sensor is a multilayer structure with alternating layer of condutive and insulating materials. The sensor structure has three electrodes: a touch plate, a guard layer, a ground plane, each of which are separated from each other by insulating layers. The sensor is operated by detection electronic circuitry which function in a either a self excited mode or an externally excited mode. This sensor is capable of detecting objects in a sensing region several feet away from the sensing surface and is particularly suitable for automobile applications, such as detecting potentially jamming objects in power (auto-closing) windows, doors, and the like.
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Citations
25 Claims
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1. A capacitive sensor for detecting the presence of an object in a sensing region comprising:
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a ground plane; a first insulating layer disposed on said ground plane; a guard layer disposed on said first insulating layer; a second insulating layer disposed on said guard layer; a touch plate disposed on said second insulating layer; an oscillator means for supplying an excitation signal to said touch plate; and a driving means for supplying an excitation signal to said guard layer such that the capacitance between said guard layer and said ground plane substantially cancels the capacitance between said touch plate and said ground plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A capacitive sensor for detecting the presence of an object in a sensing region comprising:
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a ground plane; a first insulating layer disposed on said ground plane; a guard layer disposed on said first insulating layer; a second insulating layer disposed on said guard layer; a touch plate disposed on said second insulating layer; and an inductor in parallel to said sensor, said inductor and said sensor forming an oscillator means to excite said sensor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for detecting the presence of an object in a sensing region comprising:
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providing a ground plane; providing a first insulating layer on said ground plane; providing a guard layer on said first insulating layer; providing a second insulating layer on said guard layer; providing a touch plate on said second insulating layer; exciting said touch plate by an oscillator means; exciting said guard layer by a driving means such that the capacitance between said guard layer and said ground plane substantially cancels the capacitance between said touch plate and said ground plane. - View Dependent Claims (19, 20, 21)
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22. A method for detecting the presence of an object in a sensing region comprising:
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providing a ground plane; providing a first insulating layer on said ground plane; providing a guard layer on said first insulating layer; providing a second insulating layer on said guard layer; providing a touch plate on said second insulating layer; placing an inductor in parallel to said sensor, and exciting said sensor by an oscillator means formed by said inductor and said sensor. - View Dependent Claims (23, 24, 25)
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Specification