Hitachi, Ltd.

Ricoh Printing Systems, Ltd.

Katsuyoshi Onose

Chikara Hiraoka

Toshiya Satoh

Toshio Ogiso

Katsumi Kumada

Masaru Nakano

Kazuo Kikuchi

Tomoji Kitagishi

Hiromitsu Fukuda

Akiko Oikawa

Akira Shimizu

Shigeru Obata

Shogo Matsumoto

Toru Hanashima

Kazushige Oonishi

Shoji Ukei

Takashi Kakuhashi

Hitoshi Furuyama

Keiziro Yagi

Keijiro Yagi

Toru Ohashi

Tsuyoshi Koyama

An image forming and recording apparatus, having a fixing apparatus for fixing unfixed toner image on a recording medium, wherein the fixing apparatus includes a fixing roller integrating a heater therein, an endless belt wound around the fixing roller, and three pressure members for pressing the endless belt onto the fixing roller. A pressure member located nearest to a side of entry of paper among the three pressure members is made up with a non-rotary type pressure member, and other two pressure members are made up with either one of a rotary type pressure member and the non-rotary type pressure member.

Image forming and recording apparatus with three pressure members

A fixing device in an image formation apparatus has a heating roller and a backup roller. These rollers are each coated with single silicone rubber layers around the respective peripheries of their core bars. This silicone rubber has a volume resistance value of 10 &OHgr;&middot;cm or more. The heating roller is charged with electricity of the same polarity as the polarity of toner particles due to frictional electrification caused at the time of feeding of a recording medium. The heating and the backup roller are polarized reverse to the polarity of the recording medium. A quantity of charged electricity on the backup roller is made larger than that on the heating roller. This permits the image formation apparatus to prevent offset from occurring at the time of fixing a toner image onto the recording medium to cope with various types of recording media.

Fixing device improved in offset-prevention

An electrograph apparatus includes a photoconductor, a charging device for uniformly charging the surface of the photoconductor, a developing device, a charge extinguishing device functioning so that a sheet of printed paper can be easily released, and a fixing device in which denatured silicone oil having a mercapto-group as a functional group is used as a releasing agent, for fixing a toner image copied on a printing paper, in which the fixing device is provided above the charging device and the charge extinguishing device. Further, a deodorizing device having a suction fan and a catalyst filter, at least the surface of which has a catalyst of metal oxide, is provided above the fixing device, the deodorizing device promoting reaction of ozone generated at the charging device and the charge extinguishing device with offensive substances containing mercaptan and further decomposing the ozone and the offensive substances, wherein exhaust gas containing the decomposed ozone and offensive substances is expelled in a direction opposite to the direction of the arrangement of the photoconductor and the developing device.

Electrograph apparatus enabling removal of offensive substances

A roller fixing unit for a color electrophotographic apparatus having a fixing roller and a pressing roller rotating in contact with each other, at least one of the rollers acting as a heating roller, as well as a control unit for connecting a power source to the heating device for only a predicted time duration based on a detected surface temperature of the heating roller so that the surface temperature of the heating roller reaches a setting temperature before the time when the top end of a first sheet of print medium having a color image arrives at the fixing roller in a case where the surface temperature of the heating roller in a standby state is lower than the setting temperature. The control unit is set to perform a power source connection for every sheet of print media coming out from an intermediate transfer unit in the color electrophotographic apparatus.

Controller for roller fixing unit for color electrophotographic apparatus

An electrophotographic image fixing device having preventing offsetting and affording images of high quality is provided. The electrophotographic image fixing device has a heating roller 1, made up of a mandrel 5 and an elastic layer 4 of 40-60.degree. in hardness, as measured by a spring type hardness meter of JIS K6301, provided on the mandrel, and a pressure roller 2, arranged in contact with the heating roller 1 and having a surface layer 6 the hardness of which is equal to or higher than the hardness of the elastic layer 4 of the heating roller 1. A heater 8 is provided for heating and fusion-depositing a toner image onto a toner substrate 3, by passing through the nip portion between the two rollers the toner substrate 3 on which the toner image has been formed. The linear speed of the surface of the pressure roller is 1.005-1.05 times that of the surface of the heating roller.

Electrophotographic image fixing device avoiding offset in the image by

Growing community of inventors

Hitachi, Japan

Katsuyoshi Onose