PURPOSE: To obtain a timer device having satisfactory characteristic of a copying machine by supplying a set signal and a clock from a CPU to a timer IC to easily control setting and stop of pulses.
CONSTITUTION: The output of a timer 1 and the output of a timer 2 are generated based on the clock from a CPU 11 of the timer device, and at this time, timers 1 and 2 are set by the set signal from the CPU 11. A bias voltage is changed by a developing bias circuit for the purpose of adjusting the copy density, and the output of the timer 1 is applied to a transistor TR 16 through a NAND circuit, and the collector current flowing to the TR 16 is made flow to a transformer 17 by the output pulse. The AC voltage boosted by the transformer 17 is rectified by diodes 18 and 19 to output a bias voltage Vout. The bias voltage is changed when the duty of the output of the timer 1 is changed, and the output of a TR 14 is turned on. When the bias voltage is stopped, the output of an IC 13 is set to 0 by the stop signal from the CPU 11 and the TR 14 is turned off.
SUZUKI SEIICHI
KUMAMOTO YASUHIRO
