Fujitsu Corporation

Akihiro Komuro

Yoji Houki

Tomokazu Akuta

Yoshihiro Tonomoto

Kazunori Hirose

Yoshihiro Takamatsuya

Takashi Maekawa

Keisuke Nakamura

Kazuo Shimada

Nobuyuki Hayashida

Mitsuo Nakamura

Takashi Matsuya

Yutaka Yamauchi

Tokio Muta

Hiroki Ohba

Kiyohisa Yanagita

Hirofumi Nakayasu

Shigeki Sakakura

Masato Kawashima

Hideyuki Nanba

Yasuhiro Ite

Mamoru Hokari

Minoru Takano

Makoto Matsuoka

Nobuo Fujita

Mitsuru Yamazaki

Toshihiro Matsui

Susumu Fujishima

An image forming apparatus includes a fixing unit having a heat source, a temperature detecting unit for detecting a temperature of the fixing unit, an initial operation necessity detecting unit for determining whether an initial operation should be performed in the image forming apparatus, an initial operation selecting control unit for selecting an initial operation from among a plurality of predetermined initial operations based on the temperature detected by the temperature detecting unit when the initial operation necessity detecting unit detects that the initial operation should be performed, and a control unit for controlling the fixing unit so that the fixing unit performs the initial operation selected by the initial operation selecting control unit. Furthermore, a temperature control apparatus includes a determination unit for determining, based on the detected temperature of the body, whether the temperature of the body should be increased or decreased, a temperature increasing control unit for applying an AC voltage from the AC power supply to the heater so that the temperature of the body is increased when the determination unit determines that the temperature of the body should be increased, and a temperature decreasing control unit for applying to the heater a pulse-shaped AC voltage which is repeatedly turned on and off at a frequency so that the temperature of the body is decreased when the determination unit determined that the temperature of the body should be decreased, the frequency being generally not perceived by people.

Image forming apparatus, control method for controlling the same and

A heat roller fixing device which can substantially make uniform the amount of deflection of a backup roller over the axial length thereof to improve a paper feed force at an axially central portion of the backup roller. The heat roller fixing device includes a heat roller rotatably mounted to a frame, and a backup roller pressed against a heat roller by coil springs to follow rotation of the heat roller. The backup roller includes a hollow cylinder, a solid metal shaft inserted in the hollow cylinder and having a pair of large-diameter portions spaced a given distance from each other. One of the large-diameter portions of the solid metal shaft is fixed to the hollow cylinder such as by a pin therethrough, and the solid metal shaft is biased toward the heat roller by the coil springs.

Pressure roller having deflection compensating shaft

A computer controlled printer is capable of printing at different print densities. This makes it possible to automatically determine an optimum print density according to a normal operational mode with serious consideration given to print quality and an economy operational mode with serious consideration given to operating costs, thereby decreasing the print consumables. The printer has a print mechanism section for printing papers according to print data and a print controlling section for controlling the print mechanism section. The print controlling section selects either a print density in a normal mode or a print density in an economy mode according to the normal/economy instructions and controls the print density of the print mechanism section correspondingly.

Printer with print density switching means

A toner image fixing device includes a heat roller, and a backup roller engaged with the heat roller to form a nip therebetween. A paper carrying a toner image is passed through the nip whereby the toner image is thermally fused and fixed on the paper. The heat roller, which is stained by a part of the fused toner during the fixing process, should be cleaned before a toner image is fixed on a successive paper without staining. To this end, a cleaning roller made of a felt material is pressed against the heat roller so as to be rotated together with the heat roller by a frictional force acting therebetween. The cleaning roller must be periodically replaced. The fixing device is constituted such that the replacement of the cleaning roller can be easily and quickly carried out.

Heat roller type toner image fixing device having cleaning roller

The present invention relates to an optical scanning unit used for exposing a photosensitive drum of an image forming apparatus to light, and an image forming apparatus using this optical scanning unit. This optical scanning unit comprises a light source; an optical scanning mechanism for scanning with light from the light source; a start detecting mechanism for detecting scan light of the optical scanning mechanism at an end portion of a scanning range of the scan light to detect beginning of light scanning; and a frame which has a higher rigidity than that of a frame of an image forming apparatus and to which the light source, the optical scanning mechanism and the start detecting mechanism are attached. The image forming apparatus comprises an endless photosensitive body; charging unit for charging the photosensitive body; an optical scanning unit for exposing the photosensitive body to light, including a light source, an optical scanning mechanism having the same structure as the aforementioned optical scanning unit; a developing unit for developing an electrostatic latent image formed on the photosensitive body by light exposure by the optical scanning unit; and a transfer unit for transferring a toner image on the photosensitive body onto a sheet. Alteration of the optical path of the optical scanning unit by external force applied is made smaller by making the frame of the optical scanning unit more rigid than that of the image forming apparatus.

Optical scanning unit and image forming apparatus using the same with

There is disclosed a process cartridge exchangeably provided to an image forming apparatus provided with an endless light-sensitive carrier, a mechanism for charging the light-sensitive carrier, a cleaner for cleaning residual toner on the light-sensitive carrier, a cartridge frame installed with at least the light-sensitive carrier, the charging mechanism and the cleaner, the cartridge frame having a fulcrum hole, and wherein a developing unit is detachably provided to the cartridge frame for developing an electrostatic image on the light-sensitive carrier, the developing unit including a developing unit frame having a free fit hole and connection rod freely fitted into the fulcrum hole and as well freely fitted to the free fit hole of the developing unit frame for installing the developing unit to the cartridge frame such that the developing unit is rotatably movable with respect to the cartridge frame.

Process cartridge and image forming apparatus

A printer capable of operation in an economy mode as well as in a normal mode. The printer includes a print mechanism for printing in accordance with print data. The printer also includes a print controller which controls the print mechanism. The printer is provided with a mode of operation selector for selecting between a normal mode of operation in which the print quality is relatively emphasized and an economy mode of operation in which operating costs are relatively emphasized. The print controller controls the print density at a first level when the normal mode of operation has been selected and at a second reduced level when the economy mode of operation has been selected.

Disclosed is an image forming apparatus in which separation unit for electrostatically separating a sheet from a latent image carrier is provided on an openable and closable frame. This image forming apparatus comprises a feeding path for feeding a sheet on which an image is to be formed; an endless latent image carrier; image forming unit for forming a toner image on the latent image carrier; transfer unit for transferring the toner image on the latent image carrier onto the sheet that is conveyed in the feeding path; separation unit for supplying electric charges of an opposite polarity to that of electric charges on a back of the sheet to the back of the sheet in the feeding path at a position downstream of the transfer unit, thereby separating the sheet from the latent image carrier; an openable and closable frame on which at least the separation unit is movably provided and which is to be opened to free the feeding path; a main body frame on which at least the latent image carrier is provided; and a positioning member, provided on the main body frame, for positionin the separation unit by engagement with the separation unit when the frame is closed. With this structure, even when the frame is open or closed, the precision of the position of the separation unit with respect to the latent image carrier can be improved, thus ensuring stable sheet separation.

Positioning member for a separation electrode mounted on a

In an electrographic printer which comprises a photoconductive drum (5), a precharger (7), an LED array (11), a developer (8), a cleaner (9), a transfer-charger (3) and a fuser unit (4), in which the photoconductiver drum (5), the precharger (3), the developer (8) and the cleaner are built-in in a casing to form a process cartridge (2), a housing (1) of the printer is a clam-shell type having of a lower frame (1a) and an upper frame (1b) hinged to the lower frame at the rear end thereof so that an opening is formed between both frames (1a, 1b) when the upper frame (1b) is separated from the lower frame (1a), through which opening the process cartridge (2) is inserted into and removed from the housinhg (1).

Image-forming apparatus

Growing community of inventors

Kawasaki, Japan

Akihiro Komuro