device to control the temperature of a heizwalze

摘要

PURPOSE:To prevent temperature to be controlled from being dropped from an target value by increasing the level of a set temperature and increasing the heat value of a heater when the temperature difference between the surface of a heat roller and a portion near a pyroelectric sensor. CONSTITUTION:The electric output of a pyroelectric infrared-ray sensor 23 arranged near the heat roller 4 is outputted to an input terminal ANo of an one-chip microcomputer 40 through a circuit 36 in a processing circuit 35. On the other hand, the output of a reference diode sensor 25 arranged near the roller 4 is sent from a circuit 38 in the circuit 35 to an input terminal AN1 of the computer 40 through a chopper 29. Both the signals are synthesized by a detecting signal synthesizing part. A set signal generating part generates an electric signal with a level corresponding to the surface temperature of the roller 4 to compare the output with the synthesized signal. Current supply to a heater 5 stored in the roller 4 is controlled on the basis of the output of a comparison control part in accordance with compared result.