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Fixing temperature controller for controlling a heater relative to two preset temperature levels

  • US 5,278,394 A
  • Filed: 10/16/1991
  • Issued: 01/11/1994
  • Est. Priority Date: 10/19/1990
  • Status: Expired due to Term
First Claim
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1. A fixing temperature controller comprising:

  • heater means for heating a fixing unit;

    sensing means for sensing a fixing temperature of said fixing unit and for periodically producing temperature data representing a sensed temperature; and

    control means for detecting the temperature data produced by said sensing means, said control means including means for enabling said heater means when said control means detects that the sensed fixing temperature has not increased above a first preset temperature level, and means for disabling said heater means when said control means detects that the sensed fixing temperature has increased above the first preset temperature level, said disabling of the heater means by said control means being continued until the sensed fixing temperature has decreased to a second preset temperature level which is lower than said first preset temperature level;

    said control means further including;

    data generating means for generating first and second reference data respectively representing said first and second preset temperature levels;

    selecting means for selecting one of said first and second reference data, said first reference data being selected initially; and

    a single comparator for comparing the temperature data produced by said sensing means with the one selected reference data selected by said selecting means, for generating a first-level signal when said temperature data produced by said sending means is less than the one selected reference data, and for generating a second-level signal when said temperature data produced by said sensing means is greater then the one selected reference data.

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