| 摘要 |
PURPOSE:To prevent a reference density pattern formed on an image carrier from being transferred to a transfer means or staining it by making one part or all of a device longer than the transfer means in a vertical direction to the recording material carrying direction of the transfer means. CONSTITUTION:A transfer part 16 which constitutes one of image forming means is provided with a transfer belt which is common to respective image forming stations and transfer chargers 17M, 17C, 17Y and 17K. A full color image is formed by successively transferring the toner images of respective colors formed on a photosensitive drum on a transfer material supported on the transfer belt which constitutes the transfer part 16. Then, the image forming means arranged in the black image station Pk is made longer in a thrust direction (the photosensitive drum 4K and the like are made longer downward) and longer than the transfer belt of the transfer part 16. Thus, the reference density pattern 20 for controlling toner concn. is formed at a position which is out of the transfer belt of the transfer part 16 on the photosensitive drum 4K. |
