Ricoh Company, Ltd.

Ricoh Printing Systems, Ltd.

Hitachi, Ltd.

Toshio Ogiso

Chikara Hiraoka

Shigeru Obata

Tamotsu Ikeda

Toru Hanashima

Masahiro Yagi

Shin Yamamoto

Shunichi Oohara

Yoshiharu Takahashi

Kazuo Kikuchi

Masahiro Samei

Osamu Saito

Shigeo Nanno

Yoshihiro Fukuhata

Masaru Nakano

Shogo Matsumoto

Kenji Asuwa

Tetsuji Takegoshi

Hiromitsu Fukuda

Katsuyoshi Onose

Shoji Ukei

Akira Shimizu

Hiroyuki Seki

Masahiko Saito

Kazuhiro Wakamatsu

Kenji Mori

Yasuhide Ohkubo

Junichi Matsuno

Kohta Sakaya

Yutaka Naitoh

Kazutaka Sato

Taisaku Seino

Katsumi Kumada

Keiji Kamio

Kazushige Oonishi

Yasushi Kinoshita

Akira Mori

Yukio Yamamoto

Hiroyoshi Matsumoto

Akinobu Nakamura

Chiharu Kamoshida

Yutaka Naito

Kohichi Ono

Toru Ohashi

Tsuyoshi Koyama

Kazumi Takahashi

Takashi Kakuhashi

Hitoshi Furuyama

Tuyoshi Koyama

Shunjchi Oohara

A fixing device includes a fixing rotator, a pressure rotator, a pressure plate, a pressing force adjuster, an entrance guide, an exit guide, and a guide. The pressure rotator presses the fixing rotator to form a nip between the fixing rotator and the pressure rotator. The pressure plate rotates about a fulcrum to press the pressure rotator. The pressing force adjuster adjusts a pressing force of the pressure rotator. The entrance guide guides a recording medium entering the nip. The exit guide guides the recording medium ejected from the nip. The guide guides the pressure rotator in a direction inclined from a line connecting a rotation center of the fixing rotator and a rotation center of the pressure rotator toward downstream in a conveyance direction of the recording medium.

Fixing device including a pressure rotator setting an exit guide angle and image forming apparatus incorporating same

A fixing device includes a fixing rotator, a pressure rotator, a pressure plate, a pressing force, an entrance guide, an exit guide, and a transmission. The pressure rotator presses the fixing rotator to form a nip between the fixing rotator and the pressure rotator. The pressure plate rotates about a fulcrum to press the pressure rotator. The pressing force adjuster adjusts a pressing force of the pressure rotator. The entrance guide guides a recording medium entering the nip. The exit guide guides the recording medium ejected from the nip. The transmission transmits a displacement of the pressure plate to the entrance guide and the exit guide.

Fixing device and image forming apparatus incorporating same

A fixing device includes a heater, a heating rotator, a nip formation rotator, and an entry guide. The entry guide guides each of a first recording medium having a predetermined length or more and a second recording medium having a length less than the predetermined length to the fixing nip. The entry guide includes a first and second entry guide portion. The first entry guide portion guides the first recording medium toward a harder one of the heating rotator and the nip formation rotator and has an opening. The second entry guide portion guides the second recording passing through the opening to the fixing nip along a reference line connecting an entry and exit of the fixing nip or guides the second recording medium from an area including a softer one of the heating rotator and the nip formation rotator with respect to the reference line to the fixing nip.

A fixing device includes a fixing rotator including a primary portion and a secondary portion disposed outboard from the primary portion in an axial direction of the fixing rotator. A pressure rotator contacts the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, through which a recording medium is conveyed. A primary heater heats the primary portion of the fixing rotator. A secondary heater heats the secondary portion of the fixing rotator. A primary temperature detector is isolated from the fixing rotator and detects a temperature of the primary portion of the fixing rotator. A secondary temperature detector contacts the fixing rotator and detects a temperature of the secondary portion of the fixing rotator. The primary temperature detector has a thermal time constant that is smaller than a thermal time constant of the secondary temperature detector.

Fixing device and image forming apparatus

A fixing device is removably installed inside an apparatus body including an apparatus guide. The fixing device includes a convex guide guided along the apparatus guide and a heater to heat a recording medium to fix a toner image on the recording medium. The heater includes a lateral end in a longitudinal direction of the heater. The lateral end is disposed inside the convex guide.

Removable fixing device having a convex guide and image forming apparatus

A fixing device is operable through start-up and warm-up stages and has a rotatable fixing member to fix an unfixed toner image borne on a recording medium, an opposing member to press against the fixing member and form a nip on the fixing member, a temperature detector to detect temperature of the fixing member, and a heater controlled in accordance with the temperature of the fixing member to heat the fixing member. The heater is further controlled during the warm-up stage in accordance with at least one of if the fixing member is rotating and if the detected temperature has ever arrived at a prescribed target temperature in the warm-up stage.

Fixing device capable of minimizing overshoot and image forming apparatus with same

A mechanism for guiding a recording medium into a nip formed between a first rotary member subjected to heating, and a second rotary member pressed against the first rotary member includes a guide member and a biasing member. The guide member is disposed upstream from the nip to guide the recording medium therealong. The biasing member is connected to the guide member to mechanically bias the guide member. The guide member is subjected to a constant biasing force from the biasing member and to a pressure force from the recording medium. The pressure force is opposite the biasing force and variable with a stiffness of the recording medium being guided. The guide member is movable to different operational positions depending on the biasing and pressure forces acting thereon.

Media guide mechanism, fixing device and image forming apparatus incorporating same

A fixing device is disclosed, including: a fixing rotative body, a heat source, and a control part. The control part conducts a printing temperature control which varies an ON ratio per unit time of the heat source based on a detection result of the temperature detecting part to maintain a printing target temperature in a printing state, conducts a waiting temperature control which performs an ON/OFF control based on the detection result of the temperature detecting part to maintain a waiting target temperature in a waiting state after a printing operation ends, and conducts a forcible ON control which forcibly turns on the heat source for a predetermined time before starting the ON/OFF control when the detection result of the temperature detecting part after the printing operation ends is lower than the waiting target temperature.

A fixing device includes a temperature controller that controls a temperature of a fixing rotary body based on the temperature of the fixing rotary body detected by a temperature detector so as to heat the fixing rotary body to a plurality of preset target temperatures that includes a first target standby temperature, a target fixing temperature, a target idle temperature, and a second target standby temperature. When the target fixing temperature is lower than the first target standby temperature, the temperature controller separates a pressing rotary body from the fixing rotary body to idle the fixing rotary body for a predetermined idle time period before a fixing operation starts. After the fixing operation, the temperature controller controls a heater to change the temperature of the fixing rotary body to the second target standby temperature.

Fixing device, image forming apparatus incorporating same, and fixing method

A fixing device includes a rotary fixing member, a counter member to contact the rotary fixing member, a first heater to heat the rotary fixing member, a driving unit to rotate the rotary fixing member, a temperature detector to detect a temperature of the rotary fixing member, and a contact-and-separation unit to switch between contact and separation states of the rotary fixing member relative to the counter member. In a temperature-raising operation, the driving unit causes the rotary fixing member to rotate when the temperature detector detects that the temperature of the rotary fixing member has reached a first setting temperature. The contact-and-separation unit causes the rotary fixing member in rotation and the counter member to contact each other when the temperature detector detects that the temperature of the rotary fixing member has reached a second setting temperature that is higher than the first setting temperature.

Fixing device and image forming apparatus employing the fixing device

A temperature control method for use in a fixing device that fixes a toner image on a recording sheet by passing the recording sheet through a fixing nip defined between a fixing member and a pressure member includes temperature detection, heater control, and duty control execution. The temperature detection detects a temperature of the fixing member with a temperature detector. The heater control controls operation of a heater of the fixing device by changing a duty thereof according to the detected temperature. The duty control execution executes a heater duty control to change a heater duty for a current control cycle discontinuously from that for a previous control cycle when the current control cycle precedes entry of the recording sheet into the fixing nip by a given period of time.

Temperature control method for fixing device and image forming apparatus incorporating same

In a fixing apparatus, an internal temperature detection device is arranged within a heat generation region and detects temperature of a fixing device. An external temperature detection device is arranged at the outside of the heat generation region and detects temperature of the fixing device. Heat generation in the heat generating device is stopped when temperature reaches a prescribed first high temperature detection limit and a temperature rising amount in a prescribed time period after the first high temperature detection limit is reached exceeds a prescribed threshold.

Fixing device, image forming apparatus, and method of controlling fixing device

An image forming apparatus, such as a printer, includes an image forming unit forming a toner image on an image carrier, a transfer unit for transferring the toner image onto a recording medium, a pair of a fusing rotating body and a pressure rotating body, a fusing unit for fusing the toner image on the recording medium, a temperature detecting unit for detecting the temperature on the surface of the fusing rotating body, and a control unit. An amount of decrease in the temperature of the fusing rotating body surface is measured at a predetermined time, and the time between an image formation request and the arrival of the recording medium, with the toner image formed thereon, at a fusing/nipping portion formed between the fusing rotating body and the pressure rotating body is extended when the temperature decrease amount is greater than a threshold value.

Image forming apparatus and image forming method for controlling image formation based on a temperature of a fusing rotating body

The fixing device includes a fixing unit, a pressure unit that comes into pressure-contact with the fixing unit to form a nip, and control guides. The fixing unit includes a heat roller. The pressure unit includes a pressure belt, and a pressure pad. The pressure pad is attached to a holder and pressed by a spring through a stay, thereby bringing the pressure belt into pressure-contact with the heat roller. The control guides on both sides of the pressure pad control deformation of the pressure pad in an axial direction of the heat roller to make a nip shape uniform.

A pressurizing member includes an elastic member having a uniform elastic modulus of K=EA/t, where E is a Young's modulus, A is an area of the nip portion, and t is a thickness of the elastic member in the direction of application of load. A supporting member that supports the pressurizing member has an entering portion, an exit portion, and a center portion between the entering portion and the exit portion. The thickness of the center portion in a direction of application of load is larger than thicknesses of the entering portion and the exit portion in the direction of application of load so that the supporting unit has a convex portion.

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Ibaraki, Japan

Toshio Ogiso