Image forming device

Abstract

Abstract PURPOSE:To properly control exposure by computing detection signals from plural detecting means with weight corresponding to a weighting means and outputting the mean value or total value of arithmetic result as a density signal. CONSTITUTION:The weighting arithmetic circuit 51 executes an arithmetic operation to the density signals from respective sensors 16a... with the corresponding weight stored in a memory and outputs the means value or the total value of the arithmetic result to an automatic exposure circuit 40 as the density signal. And the automatic exposure circuit 40, that is, a reference voltage generation circuit 43 generates a reference voltage according to the density signal. The reference voltage and an output voltage from a feedback transformer 34 are compared in a differential amplifier 37 and the voltage in accordance with the difference between both voltages is supplied to a trigger pulse generation circuit 44. The trigger pulse generation circuit 44 generates the trigger pulse synchronizing with the frequency of a power source 31 according to the output voltage inputted from the differential amplifier 37. The conduction angle of a thyristor 32 is controlled with the trigger pulse so as to control the effective value of the voltage impressed on both ends of an exposure lamp 8. Thus, proper exposure can be obtained.

Inventors

• 👤 Yasuhiro Iwata

Bibliographic Details