| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a tandem type image forming apparatus where the abutting conditions of a transfer medium and a latent image carrier differ between a monochrome mode and a color mode, and which adjusts the variation of a rotation phase state caused between the latent image carriers when shifting from the monochrome mode to the color mode accurately in a short time. <P>SOLUTION: Frequency generators are respectively provided corresponding to a drive motor for color and a drive motor for black. Each frequency generator detects the rotational frequency of the drive motor corresponding to the generator itself and outputs an FG signal corresponding to the rotational frequency. A rotation phase difference between a black photoreceptor drum and a color photoreceptor drum is obtained based on the FG signal, and further the relation of the rotation phase between both photoreceptor drums is adjusted by controlling the drive motor for color so as to accelerate or decelerate based on the rotation phase difference. <P>COPYRIGHT: (C)2008,JPO&INPIT |
