Differential windshield capacitive moisture sensor
First Claim
1. A differential capacitive moisture sensor having first and second surfaces for sensing moisture on the first surface of the moisture sensor, comprising at least three non-reference active electrodes located in an electrode plane parallel to, and between the planes of said first and second surfaces, defining two sensing regions on the first surface of the sensor, whereby a differential output signal is developed, which depends on the difference between the amounts of moisture in said two sensing regions, thereby enabling detection of the presence of moisture on said first surface.
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Abstract
A differential capacitive moisture sensor, relying for its operation on the time-varying couplings in two moisture-sensing regions to provide indication of presence of moisture, with selectivity of sensing surface provided by a shielding electrode, and with temperature information provided by a simultaneously-fabricated resistive temperature sensor. Various electrode connections and sensor electronics may be used.
85 Citations
40 Claims
- 1. A differential capacitive moisture sensor having first and second surfaces for sensing moisture on the first surface of the moisture sensor, comprising at least three non-reference active electrodes located in an electrode plane parallel to, and between the planes of said first and second surfaces, defining two sensing regions on the first surface of the sensor, whereby a differential output signal is developed, which depends on the difference between the amounts of moisture in said two sensing regions, thereby enabling detection of the presence of moisture on said first surface.
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28. A method for sensing moisture on a surface, comprising the steps of:
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a) providing a differential capacitive moisture sensor having first and second surfaces for sensing moisture on the first surface of the moisture sensor, comprising at least three non-reference active electrodes located in an electrode plane parallel to, and between the planes of said first and second surfaces, defining two sensing regions on the first surface of the sensor, whereby a differential output signal is developed, which depends on the difference between the amounts of moisture in said two sensing regions, thereby enabling detection of the presence of moisture on said first surface; b) applying excitation to one or more of said electrodes; c) measuring signal output at one or more of said electrodes. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A differential capacitive moisture sensor assembly for sensing moisture on two substantially parallel surfaces, comprising at least a first and second directional sensors, each of said directional sensors including:
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(a) at least three non-reference active electrodes. (b) a shield electrode, said shield electrode serving to provide directionality, said shield electrode being substantially parallel to the plane of said non-reference active electrodes; each of said sensors being structured as a laminated assembly, including, (a) a first glass laminate, having two substantially parallel surfaces, with a first surface containing said sensing regions; (b) said non-reference active electrodes located on the second surface of said first glass laminate; (c) a plastic laminate, having two substantially parallel surfaces, with a first surface of said plastic laminate adjacent to said second surface of said first glass laminate; (d) a second glass laminate, having two substantially parallel surfaces; (e) a shield electrode on a first surface of said second glass laminate; and
,(f) said first surface of said second glass laminate adjacent to a second surface of said plastic laminate; and
,wherein said first glass laminate of said first sensor serving as said second glass laminate of said first sensor.
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40. A differential capacitive moisture sensor assembly for sensing moisture on two substantially parallel surfaces, comprising at least a first and second directional sensors, each of said directional sensors including:
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(a) at least three non-reference active electrodes, (b) a shield electrode, said shield electrode serving to provide directionality, said shield electrode being substantially parallel to the plane of said non-reference active electrodes; each of said sensors being structured as a laminated assembly, including, (a) a first glass laminate, having two substantially parallel surfaces, with a first surface containing said sensing regions; (b) a plastic laminate, having two substantially parallel surfaces, with a first surface of said plastic laminate adjacent to a second surface of said first glass laminate; (c) said non-reference active electrodes located on said first surface of said plastic laminate; (d) a second glass laminate, having two substantially parallel surfaces; (e) a shield electrode on a second surface of said plastic laminate; and
,(f) a first surface of said second glass laminate adjacent to said second surface of said plastic laminate; and
,wherein said first glass laminate of said first sensor serving as said second glass laminate of said first sensor.
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Specification