Patent ID: 6711364
Filing Date: 2004-03-23
Classification: H04N

Abstract:
A color image forming apparatus comprising:a plurality of full-color image processing sections arranged along a conveyer belt, each of the image processing sections forming a toner image of a corresponding color on a recording medium in a superimposed fashion; a driver that drives the image processing sections; a compensation pattern forming unit that forms at least one compensation pattern on the conveyer belt; at least one sensor that detects the compensation pattern and outputs a signal when the compensation pattern is detected; a filter unit including, an analog filter configured to filter out some noise frequency components from the signal output by the sensor, the filtered some noise frequency components not corresponding to frequency components of the compensation pattern, and a digital filter configured to perform a fast digital filtering calculation with steep attenuation to provide a digital filtering function to remove any remaining noise frequency components not corresponding to the components of the compensation pattern not removed by the analogue filter; a compensation pattern position recognizer that recognizes the position of the compensation pattern on the conveyer belt based on the output of the filter unit; a correction value calculator that calculates a correction value based on position of the compensation pattern recognized by the compensation pattern position recognizer; and a drive controller that controls the driver based on the correction value when forming a color image on the recording medium.