Hitachi Koki Co., Ltd.

Hitachi, Ltd.

Yoshihiro Gunji

Teruaki Mitsuya

Masayasu Anzai

Kozi Kato

Takao Umeda

Hiroyuki Mabuchi

Nobuyoshi Hoshi

Makoto Nakura

Yasuo Takuma

Yasuyuki Tsuji

Akira Terakado

Hiroshi Hakuta

Shinji Asai

Shin-ichi Nishino

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

A development process and a fixing process are carried out on a front side of a recording paper. The paper recorded on the first side is transported toward a returning transportation device. The development process and the fixing process are then carried out on a back side of the paper. A nozzle for blowing out an air flow, an inverter roll for inverting the paper and the returning transportation device are arranged between the fixing station and a reversal station. The paper is deformed by the local cooling due to the air for peeling by the nozzle, the inverter roll and the returning transportation device. The portions (working regions) which receive the local cooling are arranged such that at most two of the working regions occur at any point of the recording medium paper. The inferiority of the local images in the defects in transfer and the local lowering degree in the density of the images are decreased.

Recording apparatus for printing both faces of a recording medium using

An air flow path switching device for a printing apparatus includes a sheet hopper which holds a plurality of sheets, a sheet switchback device for inverting the sheets so that both sides of the sheets can be printed on, sheet pickup devices associated, respectively, with the sheet hopper and the sheet switchback device for picking up sheets, and a blower device for supplying pressurized suction and discharge air to the sheet pickup devices. An air flow resistance existing in the sheet switchback device, when the sheet pickup device associated with the sheet hopper is connected to the blower, and an air flow resistance existing in the sheet switchback device, when the sheet pickup device associated with the sheet hopper is disconnected from the blower, are substantially equivalent.

Air flow path switching device for printing apparatus

Growing community of inventors

Ibaraki, Japan

Yoshihiro Gunji