Windshield wiper rain sensor system
First Claim
1. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
- first and second electrical conductors uniformly spaced in parallel relationship with one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape;
a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; and
an electrical insulator interposed between and coextensive with the first and second parallel, elongated conductors such that the first and second conductors and the insulator together form a thin elongated body resembling in shape a whip-type antenna for a vehicle, the insulator having an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors;
means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that the airflow parts and flows around the conductors and insulator and airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance between the conductors, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors; and
wiper control means coupled to the first conductor for generating a wiper control signal in accordance with the magnitude of the applied voltage and intensity of the rainfall.
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Accused Products
Abstract
A rain sensor system automatically controls windshield wiper action such as the length of time between windshield wiper strokes and/or wiper motor speed and is preferably integrated with a vehicle antenna. The rain sensor system comprises first and second electrical conductors spaced uniformly from one another and an electrical insulator interposed therebetween. A dual network voltage divider circuit couples the first conductor to an applied reference DC voltage level, and the second conductor is coupled to ground potential via a similar network. Airborne raindrops and moisture temporarily adhere to the exposed surfaces of the insulator to electrically couple the exposed surfaces of the first and second conductive surfaces to lower the electrical resistance therebetween. The magnitude of the applied voltage changes in relation to the intensity of rainfall or amount of raindrops adhering to the conductors to affect the rate of windshield wiper action. An rpm speed linearizing circuit may also be employed to compensate the rate of windshield wiper action in response to vehicle speed. The conductor has an elongated shape for providing self-clearing of raindrops or moisture from the sensor.
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Citations
22 Claims
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1. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
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first and second electrical conductors uniformly spaced in parallel relationship with one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape; a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; and an electrical insulator interposed between and coextensive with the first and second parallel, elongated conductors such that the first and second conductors and the insulator together form a thin elongated body resembling in shape a whip-type antenna for a vehicle, the insulator having an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors; means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that the airflow parts and flows around the conductors and insulator and airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance between the conductors, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors; and wiper control means coupled to the first conductor for generating a wiper control signal in accordance with the magnitude of the applied voltage and intensity of the rainfall. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
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first and second electrical conductors uniformly spaced from one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape; a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; an electrical insulator interposed between and coextensive with the first and second conductors whereby the insulator has an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors; a DC voltage reference circuit having an input coupled to a DC supply source for generating a generally fixed reference voltage at an output; a differential amplifier having one input coupled to the first conductor and a second input coupled to the output of the voltage reference circuit for generating a rain factor signal having a DC voltage level indicative of the rain intensity or raindrops electrically coupling the first and second conductors; a speed detector for generating a DC voltage level corresponding to the speed of a vehicle; a voltage multiplier circuit, the multiplier circuit having a first input coupled to an output of the differential amplifier, and a second input coupled to an output of the speed detector, an output of the voltage multiplier circuit producing a rain intensity signal having a DC voltage level corresponding to a speed-sensitized instantaneous rainfall product; and means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance therebetween, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A rain sensor system for detecting rain on a vehicle, comprising:
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first and second electrical elongated conductors having exposed conductive surfaces, the conductors being arranged in spaced parallel relationship with one another; an electrical insulator interposed between the conductors, the insulator having an insulating surface exposed between the exposed conductive surfaces of the conductors, the first and second conductors and the insulator together forming a thin elongated body resembling in shape a whip-type antenna for a vehicle; and means for mounting the elongated conductors and insulator in the airflow over a vehicle in an unobstructed location such that the airflow parts and flows around the conductors and insulator and the conductive and insulating surfaces are wetted by rain, whereby the resistance between the elongated conductors is reduced and used to detect the presence and absence of rain on the vehicle.
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20. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
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first and second electrical conductors uniformly spaced from one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape; a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; an electrical insulator interposed between and coextensive with the first and second conductors whereby the insulator has an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors, the electrical conductors and insulator cooperating to take the general shape of a vehicle antenna; an RF pre-amplifier coupled at one end to one of the electrical conductors and to be coupled at another end to a radio antenna input jack, the RF pre-amplifier boosting lower RF frequencies attenuated by the sensor circuitry; and means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance therebetween, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors.
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21. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
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first and second electrical conductors uniformly spaced from one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape; a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; an electrical insulator interposed between and coextensive with the first and second conductors whereby the insulator has an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors, the insulator being an electrically inert adhesive; and means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance therebetween, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors.
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22. A rain sensor system for automatically controlling windshield wiper action, the rain sensor system comprising:
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first and second electrical conductors uniformly spaced from one another and having first and second exposed conductive surfaces respectively, and each conductor having an elongated shape; a voltage divider circuit coupled to a DC supply voltage for imposing on the first conductor an applied voltage having a magnitude between that of the DC supply voltage and ground potential, the second conductor being coupled to ground potential; an electrical insulator interposed between and coextensive with the first and second conductors whereby the insulator has an exposed insulating surface located between the first and second exposed conductive surfaces of the respective first and second conductors, the insulator having a thermal expansion coefficient similar to that of the first and second electrical conductors; and means for mounting the conductors and insulator to project outwardly from a vehicle exterior surface in an unobstructed location into oncoming airflow such that airborne raindrops temporarily adhere to the exposed insulating surface to electrically couple the first and second conductive surfaces and lower the electrical resistance therebetween, whereby the magnitude of the applied voltage changes in relation to the intensity of rainfall or raindrops adhering to the first and second conductors.
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Specification