Hitachi, Ltd.

Akiko Oikawa

Toshiya Satoh

Toru Miyasaka

Tomoji Kitagishi

Katsuyoshi Onose

Masahiko Saito

Akira Shimada

Keijiro Yagi

Keiziro Yagi

A toner for use in a color electrophotographic system ensures a sufficient offset resistance without oil being supplied, and meets requirements for color development, transparency and durability to withstand commercial use. The toner for an electrophotographic system has a resin consisting of two or more resin mixtures having a different degree of crosslinking, the overall occupancy rate of mold releasing agent present as a domain in one particle of the toner is 1 to 10%, and the average dispersion diameter of the mold releasing agent is 10 to 50% of the toner particle diameter.

Electrophotographic toner, production method thereof and electrophotographic image forming system

An image forming apparatus for an electrophotographic process utilizes an agglomerate of toner powder so as to avoid scattering of toner powder. When the agglomerate is crushed or de-agglomerated to fine toner powder, only toner powder having a proper particle size for electrophotography is selected by a mesh member through which the toner must pass. The process can be utilized for a single component toner developing system and a component toner developing system.

Developing apparatus and process for an electrophotographic process

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.

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Hitachi, Japan

Akiko Oikawa