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INTERMITTENT CONTROL DEVICE

  • US 3,643,145 A
  • Filed: 04/18/1969
  • Issued: 02/15/1972
  • Est. Priority Date: 04/18/1969
  • Status: Expired due to Term
First Claim
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1. In combination, wiper drive means including an electric motor for driving a wiper blade over a windshield in repeating wiping cycles, and automatic control means for activating and deactivating said drive means intermittently to drive said wiper blade through repeating wiping cycles interrupted by dwell periods, said control means including variable-resistance means and automatically varying the value of said variable-resistance means in response to the moisture on the windshield while the drive means is activated and controlling the length of time of said dwell periods in response to the value of said variableresistance means, the length of time of the dwell periods varying inversely with the moisture on the windshield, said variableresistance means comprising a thermistor and a heating element for varying the temperature of said thermistor, the temperature of said heating element being responsive to and proportional to the motor current, said control means including a capacitor and connecting said capacitor with said thermIstor to control the length of time of said dwell period.

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