摘要 |
An image forming apparatus has a plurality of image forming units for forming images in various colors, and transfers images formed by these image forming units onto a transfer belt an overlapping manner. The image forming apparatus includes a control unit for outputting a predetermined control signal in order to form a color-shift detecting pattern with respect to the transfer belt by employing a plurality of these image forming units, and a pattern detecting sensor for reading the color-shift detecting pattern formed on the transfer belt by this control unit. Under normal operation, the control unit controls forming operation of color-shift detecting patterns by using only commonly-used color image forming units, while the control unit does not form a color-shift detecting pattern by using a specific-color image forming unit.
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