Mita Industrial Co., Ltd.

Sharp Kabushiki Kaisha Corporation

Mita Industrial

Shoji Tomita

Masahiko Maeda

Masao Uyama

Masayuki Nakashima

Shuhichi Morikuni

Kenichiro Kitajima

Akihiro Watanabe

Tsutomu Nagata

Mitsushi Kuroki

Takashi Hirota

Toshio Nishino

Tsutomu Uezono

Toru Yosioka

Kouji Unemo

Provided is an image forming apparatus including a charging device for charging a photoreceptor drum, a developing device for developing an electrostatic latent image formed on the photoreceptor drum, a developing bias applying device for applying a developing bias voltage to the developing device, a toner image density sensor for detecting an image density of a toner image formed on the photoreceptor drum, and a control portion for controlling an output value of the developing bias applying device, in which the control portion adjusts the developing bias voltage based on an average print coverage of document in previous printing jobs.

Image forming apparatus and image forming method and developing bias voltage adjustment therein

An image forming apparatus is provided having a mechanism that toner density of a toner image is automatically adjusted based on a toner patch. In an image forming apparatus including a document conveying section, a document reading section, an image forming section, a sheet discharging section, a sheet feeding section, a patch density detecting section, and a toner density adjusting section for adjusting density of a toner image depending on a result detected by the patch density detecting section, there are further provided a patch forming section for forming a toner patch, an operation detecting section for detecting an operating state of the patch density detecting section, and a patch printing section for printing the toner patch in response to such a result detected by the operation detecting section that the patch density detecting section does not properly operate, thereby adjusting the toner density based on the patch image.

Image forming apparatus and method with process control for stably forming images

A latent electrostatic image developing device for use in developing a latent electrostatic image to a toner image in an image forming machine. The device includes a developing roller within a development housing for holding a developer on its surface in a developer holding zone and conveying the developer, which is held to a developing zone, in order to apply it to a latent electrostatic image. A restricting portion has a blade which includes a rigid part for acting on the surface of the developing roller in a developer restricting zone located between the developer holding zone and the developing zone in order to restrict the amount of the developer held on the surface. The blade is caused to protrude to the upstream side as viewed in the direction of movement of the developing roller, and that border of its protrusion facing the developing roller is provided with a C 0.1 to 0.6 mm chamfer (C being the JIS designation for a 45 degree chamfer).

Latent electrostatic image developing device having regulating blade

An apparatus for developing an electrostatic latent image includes a developing agent application device which holds the developing agent on the surface thereof in the developing agent-holding zone, and conveys the thus held developing agent into a developing zone to apply it onto the electrostatic latent image. A limiting device is included for limiting the amount of the developing agent held on the surface of the developing agent application device in a developing agent limiting zone located between the developing agent holding zone and the developing zone. The limiting device includes a blade made of a rigid member that is brought into forced contact with the surface of the developing agent application device, a blade support device for supporting the blade in a manner such that a first surface thereof is forced into contact with the surface of the developing agent application device, and a resilient urging device which is disposed on a side of a second surface of the blade. The blade support device includes lower support members for supporting the lower end at the blade. The application device has an Asker C hardness between 67 to 85, the blade exerts a line pressure of 40 to 90 g/cm, and the developing agent thickness is limited in the range of 20 to 27 .mu.m.

Apparatus for developing an electrostatic latent image having limiting

An apparatus for developing an electrostatic latent image which includes a developing agent application assembly and a limiting device for limiting the amount of the developing agent held on the surface of the developing agent application assembly. The limiting device is made of a rigid member such as a sheet glass and its one surface is brought into forced contact with the surface of the developing agent application assembly.

Developing device with rigid member toner limiting means

A developing process excellent in the reproducibility of images is disclosed. In reproducing multiple fine lines, the line width can be kept uniform in the respective lines and front end chipping or rear end chipping can be prevented, and a high-density and high-quality image can be formed, by comprehensively setting developing conditions so that the relaxation time measured under dynamic conditions in an electric circuit comprising a developing sleeve, a surface of a photosensitive material and a developing layer interposed therebetween is set within a certain range; carrying out the sliding contact between the magnetic brush of the developer and the surface of the photosensitive material so that the frequency of the contact of a carrier with the photosensitive material is set within a certain range; or establishing a specific relation among the rotation number of the developing sleeve, the saturation magnetization of the magnetic carrier and the flux density of magnetic poles in the developing sleeve or further setting the contacting frequency of the carrier within a certain range.

Developing process excellent in image reproducibility

A developing sleeve for a magnetic brush developing unit, which is provided with a plurality of axially parallel grooves formed at a predetermined pitch in the circumferential direction on the surface thereof, is disclosed. Each of the grooves and the interfacing portion between each groove and its adjacent circumferential surface curve gradually and gently in section in the circumferential direction of the developing sleeve. The pitch for the formation of the grooves is set to be equal to or larger than the difference in travel length between the surface of the developing sleeve and that of a photosensitive drum during the time required for a point on the photosensitive drum to move along the full length of a developing area.

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Yao, Japan

Shoji Tomita