Fujitsu Corporation

Kouichi Kobayashi

Hirofumi Nakayasu

Youji Houki

Tsutomu Nagatomi

Takeo Kojima

Morihisa Kawahara

Hiroji Uchimura

Yoshihiko Taira

Masahiro Wanou

Masakazu Kinoshita

Takao Sugano

Hidenori Fujioka

Tsutomu Kawai

Kazuhiro Tamada

Hiroyuki Kaneda

Kazuhiko Hamazoe

Akihisa Sota

Kaneastu Uchiyama

Masakazu Kanaka

Shinichirou Yamamoto

Masao Konisi

Electrostatic developing units are arranged in the record paper conveyance direction, form dot latent images in conformity with image dot data through the issue of scanning light on photosensitive drums in rotation, and after developing by toner components, transfer dots onto record paper for development. For each lighting noticeable dot amount image dot data, a quantity-of-light control unit provides control and output of optical energy of the noticeable dot on the basis of peripheral dots which may have influence on the size of the noticeable dot on the record paper, for example, in response to the distance from the peripheral dots.

Electrophotographic apparatus with quantity-of-light control

An image forming apparatus includes a transport mechanism transporting a recording medium on a belt which is transported at a constant speed in a transport direction, a plurality of electrostatic recording units arranged in the transport direction of the recording medium and transferring toner images of different colors, a positional error detecting part using the toner image of a reference color transferred by one of the electrostatic recording units as a reference image, and relatively detecting positional error information related to positional errors of the toner images of remaining colors transferred by the remaining electrostatic recording units with respect to the reference image, and a positional error correcting part relatively correcting the positional errors of the toner images transferred by the remaining electrostatic recording units based on the positional error information. The positional error detecting part includes a part for controlling the electrostatic recording units to transfer at least two resist marks on the belt at a scan starting end and a scan terminating end of the belt in a main scan direction which is perpendicular to the transport direction of the recording medium, with respect to each of the colors, and a second part, including a sensor detecting the resist marks, for detecting positional error quantities of the resist marks of each of the remaining colors with respect to the resist marks of the reference color based on detection times of the resist marks of reference color and the remaining colors.

Positional error correction for color image forming apparatus

A drum phase correction unit for detecting rotational positions of a plurality of photosensitive drums by means of a plurality of drum position sensors and corrects to set rotational phases of the drums to predetermined phases in such a manner that transfer positions on drum circumferential surfaces relative to a belt when employing the thus detected rotational positions as their respective references have a specific relationship including coincidence. A positional offset detection unit detects positional offsets of transfer image on recording paper attributable to the wow and flutter in a drive system including the belt and the photosensitive drums. On the basis of the thus detected positional offsets, a wow and flutter correction unit corrects the positional offsets of the transfer images on the recording paper attributable to the wow and flutter.

Printing apparatus

A toner developing quantity detection unit operates a plurality of electrostatic recording units to transfer Y, M, C and K color component toner marks onto a belt. A toner developing quantity correction unit detects toner developing quantities per unit area of color toners on the basis of detection signals of the color component toner marks on the belt optically detected by a sensor. The toner developing quantity correction unit corrects the toner developing quantities so as to allow the toner consuming quantities of the plurality of electrostatic recording units to be substantially the same level, on the basis of the thus detected toner developing quantities.

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Kawasaki, Japan

Kouichi Kobayashi