JPS5731011A - Temperature control device - Google Patents

Abstract

PURPOSE:To elevate a copying speed and to effectively utilize electric power, by applying full voltage to a heater immediately after the electric power supply is turned on, and applying to the heater a pulse of duty ratio which is varied depending on whether an exposure lamp is lighted or not in the course of copying. CONSTITUTION:Immediately after an electric power supply 8 is turned on, an output of a temperature detector 3 is lower than that of a reference temperature setting circuit 4, therefore, full voltage is applied to a heater 10 by operating a heater pulse controlling circuit 2 by an output of a comparing circuit 5. When a temperature of the heater 10 rises and an output of the detector 3 coincides with that of the circuit 4, the circuit 5 stops an output of full voltage of the circuit 2. In this case, since an output of an exposure lamp controlling circuit 1 is in a low level, a pulse controlling circuit 7 supplies a pulse, for instance, corresponding to duty ratio 4/5, to a circuit 11, therefore, voltage is applied to the heater only in the pulse period whose duty ratio is 4/5. Subsequently, when an exposure lamp 9 is turned on, an output of the circuit 1 becomes high, the circuit 7 supplies a pulse, for instance, corresponding to duty ratio 2/5, to the circuit 11, and in this period, voltage is applied.