Ricoh Company, Ltd.

Asahi Glass Company, Limited

Naohiro Kumagai

Junpei Fujita

Kazuki Yogosawa

Yuuji Wada

Kenji Sugiura

Seiichi Kogure

Takeshi Shintani

Masato Yanagida

Masami Tomita

Toshio Koike

Masanori Kawasumi

Eisaku Murakami

Takeshi Uchitani

Hiroyuki Nagashima

Atsushi Sampe

Takehide Mizutani

Hirokazu Ishii

Satoshi Hatori

Kaoru Yoshino

Akira Fujimori

Nobuyuki Taguchi

Shinya Tanaka

Yutaka Takahashi

Takayuki Sasaki

Takaaki Tawada

Shinichi Kawahara

Yuji Arai

Takahiro Suzuki

Yuusuke Furuichi

Shin Hasegawa

Daisuke Tomita

Ken Amemiya

Yoshiyuki Kimura

Takatsugu Fujishiro

Yoshiki Hozumi

Nobuo Kuwabara

Masanari Fujita

Shuji Tanaka

Masaharu Furuya

Hiroshi Hosokawa

Kazuhiko Watanabe

Hideo Yoshizawa

Keigo Nakamura

Tomoya Adachi

Takashi Ito

Tatsuya Ohsugi

Hiroyoshi Haga

Hideyasu Seki

Ryohta Gotoh

Yusuke Mitani

Hiromichi Ninomiya

Yuta Azeyanagi

Yasuhito Kuboshima

Naoto Kochi

Takeshi Tabuchi

Tokuya Ohjimi

Hiroki Nakamatsu

Takuji Yoneda

Atsushi Nagata

Toshitaka Yamaguchi

Kenji Honjoh

Jyunya Sakuraba

Masayoshi Nakayama

Katsuya Kawagoe

Mugijiroh Uno

Norio Kudo

Kazunori Karasawa

Hiroya Hirose

Hiroomi Harada

Daisuke Kaku

Kentaroh Matsumoto

Tsutomu Yamakami

Atsuhsi Sampe

Yoshio Hattori

Mitsuru Takahashi

Eiji Kurimoto

Takeo Suda

Ryo Hasegawa

Hideki Zemba

Kenji Sengoku

Hiroshi Mizusawa

Junichi Ichikawa

Shinya Karasawa

Tokuya Ojimi

Chitoshi Suzuki

Hiroki Matsuura

Yoshinori Ozawa

Norio Kudoh

Yoshinori Toyota

Takeaki Arai

Shigeru Ikai

Akio Horie

Daisuke Hirano

Teruyuki Kasuga

Chohtaroh Kataoka

Yasuyuki Sasao

Hideo Sakurai

Hisakazu Harada

Masahito Furumi

An image forming apparatus includes a fixing device, a power supply, and a transfer device. The fixing device includes a fixing belt grounded via a protective resistor, a heater contacting the fixing belt, and a pressure rotator grounded and facing the fixing belt to form a nip. The power supply applies an alternating current voltage to the heater. The transfer device includes a transferor grounded and an opposed rotator facing the transferor to form a nip. The transferor has a transfer resistance Rt satisfying a following expression, where Rf is a resistance value of the protective resistor, Rp is a resistance value of a recording medium, jXs is an impedance of the fixing belt, and jXh is an impedance of the heater.

Image forming apparatus having transfer member with specific resistance

An image forming apparatus includes a heating device, a rotator, and a blade. The heating device includes a heater extending in a direction orthogonal to a conveyance direction of a recording medium. The heater includes a heat generator and generates a larger heat amount at one end than at a center. The blade includes a rubbing portion extending in the direction. Both ends of the rubbing portion face both ends of the heater. The rotator and the blade are configured such that a friction force between the rotator and one end of the rubbing portion is smaller than a friction force between the rotator and the center of the rubbing portion in the direction.

Image forming apparatus

An image forming apparatus includes a plurality of image bearers and a rotatable transferor. Images borne on the plurality of image bearers are transferred to the transferor. The transferor has an elastic power larger than an elastic power of each of the plurality of image bearers, and a difference in elastic power between the transferor and a most upstream image bearer in a rotation direction of the transferor is smaller than a difference in elastic power between the transferor and any other image bearer except the most upstream image bearer of the plurality of image bearers.

A belt device includes a belt wound around a plurality of rollers, one of the plurality of rollers, and a belt contact member disposed on the one of the plurality of rollers. The belt rotates along with the plurality of rollers. The belt contact member faces an edge of the belt in an axial direction of the one of the plurality of rollers and includes a flat portion and a separation portion. The flat portion forms a plane perpendicular to the axial direction of the one of the plurality of rollers. The separation portion is disposed outboard of the flat portion in a radial direction of the one of the plurality of rollers and has a surface located farther from the edge of the belt than the flat portion in the axial direction of the one of the plurality of rollers.

Belt device, belt regulator, roller unit, and image forming apparatus

A belt control device includes a plurality of rollers, a belt wound around the plurality of rollers and configured to rotate along with the plurality of rollers, a belt contact member that the belt contacts when the belt moves in an axial direction of the plurality of rollers, and a shaft displacement member movable in the axial direction and including an inclined face inclined with respect to a surface of the belt to control movement of the belt in the axial direction. The belt, the belt contact member, and the shaft displacement member are configured to make a frictional force between an edge of the belt and the belt contact member greater than a frictional force between the belt contact member and the shaft displacement member.

Belt control device and image forming apparatus incorporating same

An improved image forming apparatus includes an image bearer, a nip forming member, a transfer power source, and a controller. The controller switches a transfer mode between a first mode to transfer the toner image onto a first type sheet having a surface smoothness higher than a surface smoothness of a second type sheet and a second mode to transfer the toner image onto the second type sheet. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of greater than or equal to 50% that is a duty on the side of the opposite-peak value in the first mode. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of less than 50%, which is different from the opposite-peak duty of the first mode, in the second mode.

Image forming apparatus and image forming method

An image forming apparatus includes a belt-shaped image bearer, a transferer, a guide, two rotators, and a support. The image bearer has an image bearing surface to bear an image thereon. The transferer forms a transfer section between the transferer and the image bearer, to transfer the image onto a recording medium. The guide is disposed upstream from the transfer section in a delivery direction of the recording medium, to guide the recording medium toward the transfer section. The two rotators are disposed upstream from the transfer section in a moving direction of the image bearer and in contact with a non-image bearing surface of the image bearer opposite to the image bearing surface, a first rotator being closer to the transfer section than a second rotator. The support supports the first rotator and the guide and adjusts a position of the first rotator and a position of the guide.

Image forming apparatus with a support to adjust a rotator and a guide

An image forming apparatus includes an image bearer to bear a toner image, a nip forming member contacting the image bearer to form a transfer nip, and a transfer power source. The transfer bias has a transfer peak value to electrostatically move toner from the image bearer to the recording sheet and an opposite-peak value to electrostatically move less toner from the image bearer to the recording sheet than the transfer peak value. An opposite-peak duty of the transfer bias is less than 50%. The opposite-peak duty is tr/T&#xd7;100% where T is one cycle of the transfer bias and tr is a time period during which the transfer bias is on a side of the opposite-peak value relative to an offset voltage of the transfer bias in the one cycle T.

Image forming apparatus and image forming method for controlling a secondary transfer bias according to recording sheet type

An image forming apparatus includes an image bearer, an intermediate transferor, a secondary transferor, a plurality of rotators including a secondary driving rotator, and a detector. The image bearer bears a detection image. The detection image is transferred from the image bearer to the intermediate transferor at a primary transfer position. The secondary transferor is looped around the plurality of rotators and disposed in contact with the intermediate transferor at a secondary transfer position where the detection image is transferred from the intermediate transferor to the secondary transferor. The secondary driving rotator drives the secondary transferor. The detector detects the detection image on the secondary transferor at a detection position. With this configuration, a distance from the secondary transfer position to the detection position on the secondary transferor is an integral multiple of a circumference of the secondary driving rotator.

A belt device includes a belt unit including a plurality of rotators and a belt looped around the plurality of rotators. The belt device further includes a frame including a plurality of support portions to support the belt unit, a biasing member to bias the belt unit supported by the frame in a predetermined direction, and an adjuster to adjust a position of at least one of the plurality of support portions.

Belt device including support portions and an adjuster to adjust positions of the support portions

An image forming apparatus includes an image bearer including a first image portion to bear a first toner image, a second image portion to bear a second toner image, and a non-image portion to bear an adjustment pattern. A transferor forms a transfer nip with the image bearer. A controller controls the power source to output an image bias as a transfer bias to transfer the first toner image and the second toner image onto a first recording medium and a second recording medium, respectively, in the transfer nip when the first image portion and the second image portion pass through the transfer nip and output a non-image bias as the transfer bias when the non-image portion passes through the transfer nip. The controller performs a constant current control on the image bias and performs a constant voltage control when the image bias switches to the non-image bias.

A belt unit is detachably attachable to a body of an image forming apparatus. The belt unit includes a belt, a pressing member, and a frame. The belt is wound around a plurality of supports to travel in a belt travel direction. The belt includes a base layer and an elastic layer. The pressing member presses warping on an edge of the belt. The frame supports the plurality of supports. The pressing member is positioned on the frame.

Belt unit, transfer unit, and image forming apparatus including a pressing member that presses an edge of a belt

An image forming apparatus includes an image bearer; a toner image forming device; an intermediate transferor; a primary transfer power source; a secondary transfer nip forming device; and a secondary transfer power source to output a secondary transfer bias. One of two peak values of the secondary transfer bias is a transfer peak value to provide a greater transfer-directional force to move toner from the intermediate transferor toward the recording medium in the secondary transfer nip. An absolute value of the transfer peak value is greater than an absolute value of the primary transfer bias.

Image forming apparatus and transfer bias control

An image forming apparatus includes a plurality of image bearers, a transfer bias member, and a power source. When the transfer bias member transfers a color toner image onto a recording sheet, a second peak value of a peak-to-peak of a transfer bias, which is smaller than a first peak value of the peak-to-peak in an electrostatic force to move toner from the image bearers or an intermediate transfer body to the recording sheet, is zero or has a first polarity to generate the electrostatic force in a transfer direction to move toner from the image bearers or the intermediate transfer body to the recording sheet. When the transfer bias member transfers a monochromatic toner image including only black toner onto the recording sheet, the second peak value is zero or has a second polarity to generate an electrostatic force in an opposite direction to the transfer direction.

An endless rotatable belt device including an endless rotatable belt, a scale tape bonded on the belt, at least one optical sensor to detect a scale pattern, and auxiliary tape to cover at least one of the first end and the second end of the scale tape of the belt. The scale tape has a first end and a second end and includes at least one scale pattern. The auxiliary tape has a lower surface friction coefficient than the surface friction coefficient of the scale tape.

Belt device and image forming apparatus including same

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Kanagawa, Japan

Naohiro Kumagai