Ricoh Company, Ltd.

Takashi Hodoshima

Toshiyuki Andoh

Takashi Hashimoto

Seiji Hoshino

Hidetaka Noguchi

Katsuhiro Aoki

Tatsuhiko Oikawa

Hajime Oyama

Satoshi Muramatsu

Nobuo Kasahara

Tsukuru Kai

Yasuo Miyoshi

Junichi Matsumoto

Makoto Komatsu

Hiromichi Matsuda

Hisashi Shoji

Tetsuo Watanabe

Ichiro Kadota

Osamu Ariizumi

Hiroyuki Matsushiro

Hiroshi Ishii

Koichi Kudo

Nobutaka Takeuchi

Noriyoshi Tarumi

Hiroshi Saitoh

Koji Suzuki

Shunji Katoh

Toshihiro Sugiyama

Fumio Kishi

Kouji Ishigaki

Masahiko Kato

Kazuyuki Nakahara

Yuichi Hirose

Teiichiro Takano

Ichirou Komuro

Jun-ichi Matsumoto

An image formation apparatus includes an image carrier; a driving source generating a driving force for the image carrier; a drive transmission unit; a driving control unit controlling the driving source; an image formation unit forming an image on a surface of the image carrier; a transfer nip between a transfer member and the surface of the image carrier; a driving-force exerting unit exerting a driving force on any one of the image carrier and a first drive transmission member on a drive transmission path, and a specific drive transmission member imparting weakest spring characteristics among drive transmission members to a drive transmission system; a detecting unit detecting an estimation parameter used in estimating a driving-load-torque variation amount of the image carrier; a torque-variation-amount estimation unit; and a driving-force control unit controlling the driving force to cancel the driving-load-torque variation.

Image formation apparatus, driving control method, and computer program product

A load torque variation upon entry or exit of a sheet into a nipping portion is reduced while a nipping force necessary for image formation is provided. An image transfer apparatus, an image fixing apparatus, or a registration apparatus comprises an opposite roller, a transfer roller, and a compression spring for pressing the opposite roller onto the transfer roller. A sheet of transfer material is transported into a nipping portion between the opposite roller and the transfer roller, where an image on the opposite roller is transferred to the transfer material. The apparatus includes a retaining unit configured to retain a certain distance between the first rotating body and the second rotating body as long as the thickness of the transfer material that passes through the nipping portion remains the same.

Image transfer apparatus, image fixing apparatus, and registration apparatus which prevent a load torque variation upon entry or exit of a sheet into a nipping portion

In an image forming apparatus, a distance adjusting unit adjusts an inter-unit distance between a contact unit and an image carrier by moving the image carrier or the contact unit by applying an opposing force to the image carrier or the contact unit against a biasing force applied by a biasing unit based on thickness information of a recording sheet acquired by a thickness-information acquiring unit and data indicating a relationship between the thickness information and an inter-unit distance change amount stored in a data storage unit.

Image forming apparatus

A belt meandering preventing device includes a belt displacement detection unit detecting the amount of displacement in a belt width direction of an endless belt rotatably stretched over support parts; and a belt meandering correction unit correcting the displacement in the belt width direction of the endless belt based on the amount of displacement detected by the belt displacement detection unit. The belt displacement detection unit includes a moving part moving in association with the displacement of the endless belt or an edge of the endless belt in the belt width direction and optical sensors outputting signals with output levels corresponding to the proportions of the moving part in optical paths of the optical sensors. The optical sensors are arranged such that the output levels of the optical sensors change as the endless belt is displaced in the belt width direction in a predetermined high-resolution detection range.

Belt meandering preventing device and image forming apparatus including the same

A transfer roller lies opposite to a supporting roller across an image carrying belt and abuts against the outer surface of the image carrying belt to form a transfer nip. A driving force transmission unit transmits driving force from a driving source to a driving roller. A drive control unit performs drive control of the driving source. A feedforward control unit performs feedforward control on the driving source via the drive control unit. An entry detecting unit detects entry of a sheet in the transfer nip. The feedforward control unit considers an entry detection signal output by the entry sensor as a trigger for performing feedforward control after a predetermined time.

Transfer device and image forming apparatus

A sheet conveying device includes a pair of upstream rollers and a pair of downstream rollers each including a drive roller and a driven roller, a calculating unit, and a control unit. The upstream rollers include a measuring unit that obtains speed information of the upstream rollers. The calculating unit calculates a target value based on the speed information. The control unit controls the speed of the drive roller of the downstream rollers based on the target value.

Image forming apparatus and sheet conveying device having upstream and downstream rollers

An image-carrier driving unit drives an image carrier. An image forming unit forms an image on the image carrier. A moving-member driving unit drives a moving member that is movable towards and away from the image carrier. A detecting unit detects a position of the moving member at predetermined sampling times while the moving member is moving. A movement control unit performs a feedback control on the moving-member driving unit such that a detection result of the detecting unit follows a target value corresponding to each of the predetermined sampling times when the moving member moves while the image forming unit is forming the image on the image carrier.

Image forming apparatus for controlling movement of a moving member

An image forming device is disclosed that is able to enlarge a gap of a nipping portion with a simple and inexpensive structure, and able to reduce impact when a front end of a recording sheet runs into or a back end of the recording sheet passes through the nipping portion. The image forming device includes an image carrying unit, an image forming unit, a transfer unit, a conveyance unit, a determination unit that determines whether a thickness of the recording sheet is greater than a threshold value, and a cam member that rotates to enlarge or reduce the gap of the nipping portion between the image carrying unit and the transfer unit according to rotational positions of the cam member. When the thickness of the recording sheet is greater than the threshold, the cam member rotates so that the gap of the nipping portion is enlarged.

Image forming device

A driving apparatus includes a driving unit, a driven unit driven by the driving unit, a driving control unit configured to control the driving unit by performing feed-forward control based on feed-forward target data determined in advance to reduce a speed change of the driven unit. The speed change of the driven unit is expressed substantially as a positive half cycle of a sinusoidal waveform having an amplitude and a time duration, and the feed-forward target data is calculated from the amplitude and the time duration to represent a rectangular waveform approximating the positive half cycle of the sinusoidal waveform.

Driving apparatus and image forming apparatus

A fluctuation detecting unit detects a fluctuation of an endless belt generated when a sheet is brought into contact with a predetermined position of the endless belt at an upstream side in a conveying direction from a nip portion based on fluctuation information acquired by a fluctuation information acquiring unit. An entry timing estimating unit estimates entry timing of the sheet into the nip portion based on a detection of the fluctuation. A correction control unit corrects a speed fluctuation of the endless belt generated when the sheet enters the nip portion by performing a feedforward control of a first driving unit based on the entry timing.

Sheet conveying device and image forming apparatus

A second rotary member is arranged opposite to a first rotary member to form a nip between them. A driving unit drives the first rotary member. A sheet-width measuring unit measures a width of a sheet to be fed into the nip. A speed compensating unit compensates a fluctuation of a rotation speed of the first rotary member occurring when the sheet is fed into the nip. The speed compensating unit adjusts a compensation target value for compensating the fluctuation of the rotation speed of the first rotary member based on the width of the sheet measured by the sheet-width measuring unit.

An image forming apparatus includes an image transfer belt, a first pressure member, a second pressure member, and an adjustable tension member. The image transfer belt is trained around multiple rollers for rotation along an endless belt travel path to convey an image for transfer to a recording sheet. The first pressure member is disposed on an outer surface of the image transfer belt. The second pressure member is disposed on an inner surface of the image transfer belt opposite the first pressure member. The first and second pressure members define an image transfer gap therebetween. The adjustable tension member is disposed on the image transfer belt adjacent the image transfer gap to adjust tension on the image transfer belt when the recording sheet enters and exits the image transfer gap.

A sheet conveying device includes a torque estimation unit that, based upon a first load torque generated at a time that a sheet-like member passes through a first nip between a first driving roller and a first driven roller of an upstream sheet conveying unit, estimates a second load torque generated at a time that the sheet-like member passes through a second nip between a second driving roller and a second driven roller of a downstream sheet conveying unit; and a control unit that controls the driving torque such that the second load torque is counterbalanced by applying a counterbalancing torque in synchronization with a timing of entry of the sheet-like member into the second nip.

An image forming apparatus of the present invention includes a bias power supply for applying a bias Vto a developer carrier on which a developer is deposited. A charge potential deposited on an image carrier, which faces the developer carrier for forming a latent image thereon, is 400 V or below in absolute value. Assume that the potential of the image carrier is lowered to Vafter exposure, that a development potential is |V&#x2212;V|, that the maximum set value of the development potential for development is |V&#x2212;V|max, and that the development potential varies in a range satisfying relations:||max+||max&#xd7;0.2||max&#x2212;||max&#xd7;0.2||max&#x2266;300 VThen image density varies by a width of 10% of image density corresponding to the maximum set value of the development potential or less.

A developing method of the present invention uses a sleeve accommodating a stationary magnet roller formed with a plurality of magnetic poles and facing an image carrier. The sleeve is rotated to convey a developer, which is made up of toner grains and magnetic carrier grains and deposited on the sleeve, to a developing zone for thereby feeding the toner grains from a magnet brush formed by the developer to a latent image formed on the image carrier. When the developing zone is seen from the image carrier side, the ratio of the total area of voids present at the tips of the magnet brush to the total area of the developing zone is selected to be 25% or less.

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Kanagawa, Japan

Takashi Hodoshima