Hitachi Koki Co., Ltd.

Kozi Kato

Masayasu Anzai

Yoshihiro Gunji

Teruaki Mitsuya

Takao Umeda

Hiroyuki Mabuchi

Nobuyoshi Hoshi

Shin-ichi Nishino

Shinji Asai

A dielectric belt 24 is retracted from a photoreceptor 2 before printing, and electrophotographic processes including a process of forming an electrostatic latent image, a developing process and a cleaning process except for a transferring process are repeated. During the repetition of the electrophotographic processes, a surface electric potential in the background of the photoreceptor 2 is measured by the electric potential sensor 10. Alternatively, a quantity of toner adhering to the background of the photoreceptor 2 is measured by the toner sensor 37 and the toner electric charge sensor 36. When the measured values are lower than the reference values, it is judged that no fringe image is generated in the recording condition, and the printing operation is carried out.

Color image forming apparatus and color image forming method thereof

An electrostatic recording control method wherein there are provided a single surface potential sensor between a first and second developer units, a detector for detecting the characteristic of a factor influencing the dark attenuation characteristic of the sensitive body, comprising the steps of: irradiating the surface of a charged sensitive body with the test pattern having prescribed exposure energy by an exposure system to form a test electrostatic image on the photosensitive body; passing the test electrostatic latent image with the developing function of the first developer unit stopping to measure the surface potential of the test electrostatic latent image by the sensor; changing the control setting potential at a position where the sensor is set according to the output from the detector; comparing the potential measured by the passing step with the control setting potential changed by the changing step to control one of the voltage to be applied to the latent image forming charger and the exposure energy for forming the test pattern so that the measurement potential is a control setting potential; forming a test electrostatic latent image on the photosensitive body after the comparing step; applying a prescribed bias to the first developer unit to form the first toner image corresponding to the test electrostatic latent image; and measuring the surface potential of the first toner image to set the bias voltage of the second developer unit according to the value measured.

Electrostatic recording control method and electrostatic recording

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Ibaraki, Japan

Kozi Kato