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Hair styling appliances and heater control circuits therefor

  • US 5,270,520 A
  • Filed: 09/23/1991
  • Issued: 12/14/1993
  • Est. Priority Date: 09/23/1991
  • Status: Expired due to Fees
First Claim
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1. A hair styling appliance comprising:

  • a heat conductive portion for applying heat to the hair;

    an electrically energizable heater element located in thermal relationship with the heat conductive portion for causing it to be heated upon application of energy;

    a temperature sensor located in thermal relationship with the heat conductive portion being connected to the heater element, the temperature sensor having a positive temperature coefficient of resistance characteristic resulting in a variable resistance which changes by no more than about 240k ohm in a temperature range between 100°

    C. and 165°

    C.; and

    pulse switching means operatively coupled to the heater and responsively coupled to the temperature sensor for controlling energization of the heater with temperature, said pulse switching means gating the heater on and off at a rate which decreases with increasing temperature in accordance with said variable resistance.

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