Fujitsu Corporation

Toshio Tooda

Yoshio Yamaguchi

Sachio Sasaki

Akira Nagahara

Takefumi Takahashi

Nobuo Kuwabara

Shigenobu Utaka

Hiroshi Kera

Haruyasu Watanabe

Yoshiya Ishiyama

Mitsuru Sato

Masatoshi Kimura

Kunihiko Sato

Hiroshi Nou

Masao Konishi

Hideki Kamaji

Mitsuhito Furukawa

Hisashi Hanzawa

Akiyoshi Iwamasa

Hideaki Iwasaki

Shizuo Takano

Ryo Kitao

Masanori Nishido

Mituru Sato

An electrophotographic image forming apparatus including a toner circulating mechanism for recovering a residual toner scraped from a photosensitive drum to a developing device. The developing device includes a housing for defining a toner chamber, a developing roller rotatably mounted in the housing, an agitator rotatably mounted in the housing and provided in the toner chamber, and a partition member mounted to the housing to define a carrier chamber between the partition member and the developing roller. The toner circulating mechanism directly returns the residual toner scraped from the photosensitive drum to the toner chamber in the developing device. The toner chamber may contain a foreign matter removing device. The partition member may have various shapes.

Electrophotographic image forming apparatus having a device for

An electrophotographic image forming apparatus includes an electrostatic latent image carrying body, an electrifying unit for electrifying the image carrying body, a light irradiating unit to form an electrostatic latent image in accordance to image information, a developing unit for discharging toner to the image carrying body to develop the latent image, a transfer unit for transferring the toner image to a recording sheet, and a cleaner for removing residual toner on the image carrying body. The toner removed from the image carrying body is recirculated to the developer receiving box. An additional toner image is formed on a position other than a first position where the electrostatic latent image is formed in accordance with the image information. The toner is removed by the cleaner without being transferred to the recording sheet and recirculated from the image carrying body to the developer receiving box.

Electrophotographic image-forming apparatus with uniform toner usage

A developing apparatus is provided for developing an electrostatic latent image on a latent image carrier by supplying the latent image carrier with a developer. This developing apparatus includes a toner accommodating chamber for accommodating magnetic toners. The apparatus also includes a developing roller, having a plurality of fixed magnetic pole members and sleeves provided along peripheries of the fixed magnetic pole members and rotating thereabout, for feeding the developer composed of magnetic carriers and magnetic toners to the latent image carrier. The apparatus further includes a developing chamber having a partition wall formed along the developing roller and assuming a configuration adapted to a shape of the developing roller, and a toner supply port for supplying the magnetic toners to the developing chamber from the toner accommodating chamber. In another mode of the developing apparatus, the center of each magnetic pole of the fixed magnetic pole members is located in a position deviating from the toner supply port. Further, in still another mode of the developing apparatus, there is employed the magnetic carrier the core of which is iron powder exhibiting strong saturation magnetization.

Developing unit having improved toner density control

An electrophotographic apparatus has a plurality of developing rollers arranged in a row in the direction of rotation of a photosensitive member so as to face the surface of the photosensitive member. Each developing roller retains on the surface thereof a developer consisting essentially of an electrically insulating magnetic toner and an electrically conductive magnetic carrier. At least the surface portion of each developing roller is driven to rotate in order to transport the developer to the surface of the photosensitive member. A developing bias voltage is applied to each of the developing rollers. Exposure is carried out by applying image light from the reverse side of the photosensitive member toward the most downstream developing roller as viewed in the direction of rotation of the photosensitive member.

Electrophotographic apparatus

Disclosed are a toner empty detecting method of and a toner empty detecting apparatus for detecting an empty state of toners in a toner hopper. The toner empty detecting method comprises: a step of taking in the output of the detecting element with every constant period; a step of comparing a detected value relative to a take-in value with an average value of the detected values during a detection period of last time; a step of counting the number of times when the detected value is smaller than the average value during a detection cycle of this time; and a step of generating a toner empty output when the count value is larger than the predetermined value. The toner empty detecting apparatus comprises: a toner sensor for detecting the toners in the toner hopper; and a control circuit for comparing a detected value relative to a take-in value when taking in an output of the toner sensor with every constant period with an average value of the detected values during a detection period of last time, comparing the count value with a predetermined value and generating an empty output when the count value is larger than the predetermined value. Even if there is a scatter in output level of the toner detection sensor, the toner empty can be thereby stably detected.

Method of and apparatus for detecting toner empty

A toner image transferring device is applied to, for example, an electrophotographic printer for electrostatically transferring a charged toner image from a photosensitive drum to a sheet or paper. The device encompasses a transfer charger disposed near the drum to form a clearance therebetween for feeding an electric charge to the sheet or paper through which the sheet or paper is passed, an electric source for supplying an electric energy to the transfer charger to give the sheet or paper an electric charge having a polarity opposite to that of the charge of the toner image, and a controller for controlling the electric energy output from the electric source the transfer charger so that a leading edge of the sheet or paper can be prevented from being excessively charged.

Transferring device controlled for preventing the leading edge of a

Growing community of inventors

Kawasaki, Japan

Toshio Tooda