Ricoh Company, Ltd.

Kazuchika Saeki

Yoshiki Hozumi

Naomi Sugimoto

Masaharu Furuya

Mitsuru Takahashi

Kazuosa Kuma

Takeshi Fukao

Yuuji Sawai

Tsutomu Katoh

Naoki Iwaya

Yasufumi Takahashi

Yoshiharu Kishi

Nobuto Yokokawa

Akira Asaoka

Toshitaka Yamaguchi

Takuya Sekine

Shinya Tanaka

Shinji Aoki

Keigo Nakamura

Haruo Iimura

Yasuhiko Ogino

Takahiro Nakayama

Hiroyoshi Haga

Tsutomu Kato

Satoru Uchida

Atsushi Tano

Ryuuichi Minbu

Kiyoshi Horikawa

An image forming apparatus includes a transfer member configured to abut against an image carrier for carrying a toner image to form a transfer nip; and a power supply configured to output a bias voltage for transferring the toner image on the image carrier onto a recording medium nipped in the transfer nip. The bias voltage includes a first voltage for transferring the toner image from the image carrier onto the recording medium in a transfer direction and a second voltage having an opposite polarity of the first voltage, the first and the second voltages being alternately output. A time-averaged value of the bias voltage is set to a polarity in the transfer direction and is set in the transfer direction side with respect to a median between a maximum and a minimum of the bias voltage.

Image forming apparatus and image forming method

A belt device for an image forming apparatus, includes an endless belt; a first and second support rollers, each including a rotary shaft, that support the belt with tension; a contacted member that contacts the belt; a shaft displacement device to displace any of the rotary shafts of the support rollers; and a main rotary shaft disposed at a side of the rotary shaft of the first support roller moved by the shaft displacement device along a stretching direction of the stretched surface of the endless belt that the contacted member contacts, relative to a contact portion between the endless belt and the contacted member, and at an opposite side of the contacted member in a direction perpendicular to the stretching direction of the endless belt. As the first support roller and the second roller rotate about the main rotary shaft, the endless belt is separated from the contacted member.

Belt device and image forming apparatus including same

An image forming apparatus includes a toner image forming device to form a toner image on a rotatable toner image bearer, a looped belt to carry a recording medium, a support roller to rotate the belt, a pressing member to press the belt against the toner image bearer, a transfer electric field generator to form an electric field to transfer the toner image onto the recording medium, and a contact member to contact an end surface of the belt as the belt moves to one side in a belt width direction. The belt includes a first portion pressed against the toner image bearer by the pressing member and a second portion adjoining the first portion. A relative position of the support roller relative to the toner image bearer and the pressing member is determined such that the second portion of the belt contacts the toner image bearer.

Image forming apparatus having an angle adjuster for a tiltable support roller

A belt tracking system for controlling the lateral position of a movable belt entrained about a plurality of generally parallel rollers for moving in a trans-axial direction perpendicular to an axial direction in which the rollers extend parallel to each other includes a roller shaft, a slidable member, and a rotation restrictor. The roller shaft extends outward in the axial direction from an axial end of a specific one of the plurality of generally parallel rollers. The slidable member is slidably disposed around the roller shaft to move along the roller shaft as the belt moves laterally outward in the axial direction. The rotation restrictor is disposed adjacent to the slidable member to restrict rotation of the slidable member around the roller shaft.

Belt tracking system, multi-roller assembly and image forming apparatus employing same

A recording medium conveying device includes an endless belt to convey a recording medium, a plurality of support rollers around which the belt is wound, to rotate the belt, and a cleaner in contact with the belt to clean the belt. One of the plurality of support rollers is a separation support roller, mounted on a tiltable rotary shaft, to separate the recording medium from the belt using a curvature of the separation support roller. The separation support roller includes a contact member to contact an edge of the belt when the belt laterally moves toward one side of the belt.

Recording medium conveying device with a separation support roller and image forming apparatus incorporating the same

A conveyor system includes a first conveyor belt entrained about a separation roller and a support roller disposed upstream from the separation roller, a second conveyor belt entrained about a first roller disposed at an uppermost stream in a transport direction of a sheet-type medium and a second roller disposed downstream therefrom, a belt alignment device to tilt a rotary shaft of the separation roller to restrict a range of belt mistracking of the first conveyor belt in a width direction thereof within a predetermined range, and a restriction member to restrict an amount of inclination of the rotary shaft such that a hypothetical extended plane, which is a hypothetical extension of the outer circumferential surface of the first conveyor belt between the separation roller and the support roller to a downstream side in the transport direction, does not contact a rotational center axis of the first roller.

Conveyor system and image forming apparatus including same

[Problem to be solved] To provide an image forming apparatus for suppressing formations of white spots and achieving high quality images, while obtaining sufficient image densities in both of the recessed parts and the projected parts of a recording medium surface. [Solution] An image forming apparatus includes a transfer memberthat abuts against a surface of an image carrier carrying a toner image and forms a transfer nip, and a power supplythat outputs a voltage (transfer bias) for causing the toner image on the image carrier to be transferred onto a recording medium P nipped in the transfer nip. The voltage is switched alternatingly between a transfer direction voltage for causing the toner image to be transferred from the image carrier onto the recording medium and a voltage having an opposite polarity of the transfer direction voltage when the toner image on the image carrier is to be transferred onto the recording medium. A time-averaged value (V) of the voltage is set to a transfer direction polarity that causes the toner image to be transferred from the image carrier onto the recording medium, and is set more in the transfer direction than a median voltage (V) between a maximum and a minimum of the voltage.

A belt assembly includes a belt formed into an endless loop, a plurality of support rollers with a rotary shaft, a shaft-end retainer, a movable supporting member, and a drive transmission device. The plurality of support rollers includes a first support roller and a second support roller. The shaft-end retainer is disposed at each end of the rotary shaft of the plurality of support rollers. The movable supporting member supports the first support roller and is movably disposed relative to the shaft-end retainer. The drive transmission device transmits a driving force to one of the plurality of support rollers. The drive transmission device and the movable supporting member are disposed on a same side as the shaft-end retainer in an axial direction of the plurality of support rollers. The drive transmission device is disposed between the shaft-end retainer and the movable supporting member in the axial direction.

Belt assembly and image forming apparatus including same

A belt positioning system for positioning a movable belt entrained about a plurality of generally parallel rollers for moving in a trans-axial direction perpendicular to an axial direction in which the rollers extend parallel to each other includes a flange. The flange is operatively connected to an axial end of a specific one of the plurality of generally parallel rollers to define a contact surface therealong which extends generally perpendicular to the axial direction to contact an adjoining edge of the belt. The contact surface of the flange is spaced apart from the axial end of the roller in the axial direction.

Belt positioning system, multi-roller assembly and image forming apparatus employing same

A belt assembly includes a belt, a plurality of support rollers, and a shaft-end retainer. The belt is formed into an endless loop, entrained about and stretched taut between the plurality of support rollers with a rotary shaft. The plurality of support rollers includes a first support roller and a second support roller. The shaft-end retainer including a first retainer and a second retainer is disposed at each end of the rotary shaft of the plurality of support rollers. The first retainer detachably holds an end of the rotary shaft of the first support roller. The second retainer detachably holds an end of the rotary shaft of the second support roller and includes a second-retainer opening from which the end of the rotary shaft of the second roller is detachable from and attachable to the second retainer in a direction perpendicular to the rotary shaft of the second support roller.

A belt tracking system for adjusting misalignment of a movable belt in an axial direction of a plurality of rollers about which the movable belt is entrained includes a slope member and a stationary shaft guide. The slope member is disposed at both ends of at least one of the plurality of rollers in the axial direction, to tilt the roller as the belt moves in the axial direction. The stationary shaft guide contacts the slope member. A distance between a contact point of the slope member that contacts the stationary shaft guide and an end portion of the slope member in the axial direction is longer than a maximum traveling distance that the slope member travels in the axial direction.

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Kanagawa, Japan

Kazuchika Saeki