Patent ID: 8436884
Filing Date: 2013-05-07
Classification: B41J

Abstract:
1. An image forming apparatus comprising: a plurality of image holding bodies; an exposure unit which includes a plurality of laser units which emits laser beams and performs main scanning and sub-scanning of the respective image holding bodies by the laser beam emitted from the respective laser units; a laser detecting unit that detects the laser beam emitted from one specific laser unit among the laser units as a reference position of the main scanning; an integrated circuit that includes a plurality of image processing circuits which process input image data in accordance with input first clock signals and output the processed image data at predetermined timing based on main scanning reference signals which is input; a plurality of laser control circuits which momentarily hold the output image data from the respective image processing circuits, output the held image data in accordance with input second clock signals, generate laser control signals for controlling the operation of the laser units in accordance with the main scanning reference signals, and output the laser control signals; a plurality of data processing circuits which are operated in accordance with the laser control signals output from the laser control circuits, convert the image data output from the respective laser control circuits into serial data signals then output the signals, output signals synchronized with detection of the laser detecting unit as the main scanning reference signals, and output clock signals having predetermined frequency as the second clock signals; a selection section which selects any one of the main scanning reference signals output from the data processing circuits and supplies the signals to the respective image processing circuits; a plurality of first gate circuits which allow and block the input of the first clock signals to the respective image processing circuits by opening and closing; a plurality of second gate circuits which allow and block the input of the second clock signals to the respective laser processing circuits by opening and closing; and a selection circuit which has a first selection mode which respectively selects the laser control signals output from the laser control circuits and supplies the selected signals to the respective laser units and the respective data processing circuits, a second selection mode which selects any one of the laser control signals output from the laser control circuits and supplies the selected laser control signals to a plurality of the laser units having the specified laser unit among the laser units and the data processing circuits and to a plurality of data processing circuits corresponding to a plurality of the laser units, and is capable of selectively setting the first selection mode or the second selection mode; and a control section that sets the first selection mode in the selection circuit while opening all of the gate circuits in a case of an image forming mode using the respective image holding bodies and sets the second selection mode in the selection circuit while closing the remaining gate circuits whereas only opening the first gate circuits and the second gate circuits which correspond to the specific image holding bodies among the respective gate circuits in a case of the image forming mode using only one specific image holding body among the respective image holding bodies.