| 摘要 |
In electrophotographic copying apparatus utilizing a photoconductive belt having markings regularly spaced apart on its back side for control of the copying operations by moving past a detector comprising a light source and a photoelement to generate signal pulses, the detector is made to perform reliably notwithstanding variations of the sensitivity of the photoelement, or of the light emission, by the provision of a circuit for emitting a detector signal proportional to the amount of light sensed by the photoelement together with a signal modifying circuit that maintains an output signal level corresponding to the average value of the detector signal and a control circuit responsive to the output signal level for controlling the intensity of the light source. |
