Ricoh Company, Ltd.

Tatsuhiko Oikawa

Toshiyuki Andoh

Takashi Hashimoto

Seiji Hoshino

Takashi Hodoshima

Hidetaka Noguchi

Makoto Komatsu

Hiromichi Matsuda

Tetsuo Watanabe

Takashi Kimura

Tetsuro Hirota

Hiroyoshi Haga

Toshihito Kamei

Yoshiaki Hanyu

Mikio Ohashi

Sumiaki Aoki

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 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.

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 includes an image carrier that carries an image and rotates, a transfer member that rotates in contact with the image carrier and transfers an image formed on the image carrier to a recording medium, a conveying unit that conveys the recording medium to a contact position where the image carrier and the transfer member come into contact with each other, and a gap forming unit that forms a gap between the image carrier and the transfer member at the contact position. The gap forming unit forms the gap immediately before the recording medium enters the contact position.

Image forming apparatus including a gap forming unit

A head driving unit the generates a driving waveform, each driving waveform including a plurality of driving pulses, and selects one or more driving pulses to be applied to a liquid drop discharging head in response to data corresponding to an image. By selecting a plurality of selection signals that defines the driving pulses to be applied to the liquid discharging head, the head driving unit can change a recording density or record multiple value images.

Head driving unit and an image forming apparatus using the same

In a printing apparatus, a printer control unit transmits image data to an engine control unit for a respective one of a plurality of bands sent by a host computer. The image data of the respective one of the plurality of bands defines a pattern of 'M' dots by 'N' lines related to an image of a corresponding band where both 'M' and 'N' denote an integer. The printer control unit transmits a band information command to the engine control unit prior to the transmission of the image data. The band information command includes a band height, a print start dot position and a print end dot position, the band height indicative of a quantity of the image data transmitted, the print start dot position indicative of a position of a print start dot with respect to all the 'N' lines in the image, and the print end dot position indicative of a position of a print end dot with respect to all the 'N' lines in the image.

Printing apparatus for increasing efficiency in transmitting image data

An automatic sheet feeder for feeding paper sheets one by one toward a body of an image recording apparatus has a feed roller and lap feed preventing device for preventing two or more paper sheets from being fed together. The lap feed preventing device is implemented as a reverse roller which is pressed against the feed roller and provided with a circumferential recess in a predetermined position thereof. When paper sheets each being formed with three holes for filing at spaced locations along the width thereof are used with the sheet feeder, the circumferential recess of the reverse roller coincides with the intermediate hole of each paper sheet being fed.

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Kanagawa, Japan

Tatsuhiko Oikawa