Hitachi Koki Co., Ltd.

Hitachi, Ltd.

Kazuo Uno

Junji Shirakawa

Masato Yamada

Masahiro Yamazaki

Teruaki Mitsuya

Takashi Suzuki

Junichi Matsuno

Yasuo Takuma

Shigeru Obata

Masato Miwa

Kimio Nakamura

Junzi Shirakawa

A belt-type transfer device which includes an endless belt rotating in contact with a photosensitive drum, with the belt being electrically charged by a corona discharger in a region of contact between the belt and the drum. A plate is provided for shielding the belt from the corona discharging in a vicinity of an outlet of the contact area to reduce electrostatic traction forces between the drum and the sheet in a vicinity of the outlet. The corona discharger may be located near an inlet of the region of contact with respect to a center thereof or a dielectric or electrically conductive film may be provided on an inner surface of the corona discharger on the contact area outlet side to increase the electrical charge of the belt at the inlet and the central portion of the region of contact. A control system detects an electric resistance value of the sheet and changes the corona discharging intensity in accordance with a detected value to stabilize an electrical charge of the belt or, a control system may be provided for slightly lowering a moving speed of the sheet as compared with a rotational speed of the drum at an outlet of the region of contact. Surface roughness of the belt is 5 .mu.m or less and the sheet delivery guides are provided having a volume resistivity of 10.sup.11 .OMEGA.cm or less, which reduces electrical charge caused on the sheet due to frictional contact.

Belt type transfer device for electrophotographic apparatus

An apparatus fixes a toner image formed on a recording medium and has a fixing roller which is rotated. The fixing roller is heated and the toner image is fixed on the recording medium being in pressed contact with said fixing roller. Offset toner particles formed on the fixing roller are decomposed into particles being too small to be perceived as a picture by an offset toner decomposing device before such large particles to be perceived as a picture are formed, and the small offset toner particles are stuck onto and removed by the recording medium. Preferably, the offset toner decomposing device is a brush roller which is rotated relative to the rotation of the fixing roller such that the brush roller and the fixing roller have equal peripheral speeds. The amount of offset toner being formed is decreased by reducing the creation of offset toner particles on the fixing roller by decreasing a torque fluctuation of a drive motor of the fixing roller.

Apparatus for fixing a toner image, fixing method and

A xerographic printing machine with at least two rollers disposed so that their axes are arranged parallel to each other. An endless belt, supported by the rollers, has a volume resistance within the range of 10.sup.9 to 10.sup.14 .OMEGA.cm. A photoreceptor is disposed adjacent to the endless belt. An endless belt charging device is disposed opposed to the photoreceptor in such a way that the endless belt is located between the endless belt charging device and the photoreceptor. An electrostatically charged toner supported on the surface of the photoreceptor is transferred to a print media. A guide member is disposed between the photoreceptor and the roller located upstream of the endless belt as viewed in the advancing direction of the endless belt. The guide device guides the advancing print media to bring the print media into contact with the endless belt.

Xerographic printing machine with an improved transfer unit

A transfer unit for a xerographic printing machine including at least two rollers and an endless belt supported by the rollers. A frame member supports the rollers. A photoreceptor is disposed adjacent to the endless belt, and a charging means is disposed opposite to the photoreceptor so that the endless belt is locate between the charging means and the photoreceptor. Pressure in the space within the transfer unit, which is surrounded by the endless belt and the frame member and contains the endless belt charging means disposed therein, is slightly higher than atmosphere pressure outside the transfer unit.

Transfer unit for xerographic printing machine with constant ventilating

A paper feed mechanism comprises a feed roller rotatable in one direction at a predetermined timing, which rotates in an overrunning manner if such need arises, a separation roller disposed in contact with the feed roller, which rotates together with the feed roller when a load torque exceeds a predetermined value, and a pickup roller disposed upstream of the feed roller in the direction of rotation of the feed roller for feeding a paper sheet according to a paper feed instruction, a device for varying the pressing force of the separation roller against the feed roller, a detector provided in the vicinity of the feed roller and the separation roller for detecting the speed of the paper sheet fed by the feed roller and the separation roller; and a controller for controlling the pressing force of the separation roller according to the detection signal from the detection.

Paper feed mechanism

A paper feed mechanism for a printing apparatus, comprises a case, a plurality of tables provided in the case for supporting at least two kinds of cut sheets thereon, the two kinds of cut sheets including large-sized cut sheets larger than each table and small-sized cut sheets substantially equal to each table, and a unit for moving the small-sized cut sheets on one table to another table when another table becomes empty of the small-sized cut sheets, wherein when the plurality of tables support the large-sized cut sheets, the plurality of tables function as one table, and when the plurality of tables support the small-sized cut sheets, the plurality of tables function separately independently of each other.

Paper feed mechanism with plural support tables for supplying cut sheets

In an electrophotographic printing machine, the endless belt has a thin protective layer on each of the inner and outer surfaces thereof which is high in mold release characteristic and effective in minimization of the deterioration in electrical characteristic of the endless belt.

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Ibaraki, Japan

Kazuo Uno