Patent ID: 6075547
Filing Date: 2000-06-13
Classification: G03G

Abstract:
A color image forming apparatus comprising:an image forming unit for forming a multicolor image on a second image support by sequentially transferring toner images related to a plurality of colors from a first image support to the second image support in an overlaying manner;a reference position detecting unit for detecting a reference mark signal every time a reference mark at a reference position on the second image support is sensed during rotation of the second image support;a laser scan start timing control unit for controlling a laser scan start timing for the image forming unit to start scanning the first image support by a laser beam, based on the reference mark signal detected by the reference position detecting unit;a phase error measurement unit for measuring a phase error between a line sync signal from the image forming unit and the reference mark signal from the reference position detecting unit by counting system clocks before the laser scan start timing; anda drive speed control unit for adjusting a rotating speed of the second image support to a controlled speed by outputting a drive pulse to a motor which rotates the second image support, the drive speed control unit determining an ON-state period of the drive pulse depending on the phase error measurement such that a timing for the reference mark detecting unit to detect the reference mark signal matches the laser scan start timing of the image forming unit.