METHOD AND CIRCUIT FOR CONTROLLING PROPORTIONAL TEMPERATURE FOR ELECTROPHOTOGRAPHIC APPARATUS

摘要

PROBLEM TO BE SOLVED: To perform temperature control by which quick response can be realized with reduced overshoot and temperature ripple by coping with various kinds of heater capacities in an electrophotographic apparatus.

SOLUTION: This method and circuit for controlling a proportional temperature is provided with: a differential amplifier circuit for amplifying a difference between detected voltage proportional to the temperature of a body to be heated and reference voltage for performing temperature setting with an amplification degree variable; and a low frequency oscillator which has output rising from the value of a triangle wave or a saw-tooth wave which is offset a little bit from zero volt. Then, proportional temperature control by which a proportional band width and a control period are variable is performed by turning on and off a heater for heating the body to be heated on the basis of the magnitude correlation of the output of the low frequency and that of the differential amplifier circuit. Though the proportional band width is varied, the upper limit of a proportional band is made to be nearly equal to a set temperature.

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