摘要 |
In an apparatus for forming multi-color image provided with a rotatable image carrying member and a plurality of image forming means each having a charging device, a scanning exposure device and a developing device; each scanning exposure device includes a beam generator and a polygonal mirror. The apparatus is further provided with a first sensor for detecting the beam passing at a start reference position on a peripheral surface of the rotatable image carrying member and for outputting a start reference signal; a second sensor for detecting the beam passing at an end reference position on the peripheral surface and for outputting a stop reference signal; and a controller to measure a time between the start reference signal and the stop reference signal and to control a frequency of clock pulses to transmit image signals for each scanning exposure device on the basis of the measured time of each scanning exposure device.
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