Ricoh Company, Ltd.

Naoko Morisawa

Daisuke Inoue

Satoshi Kojima

Hideki Sugiura

Fumihiro Sasaki

Osamu Uchinokura

Susumu Matsusaka

Motokazu Hasegawa

Yukari Isoe

A fixing device includes a rotary member comprising a heat generation layer; an excitation coil generating magnetic flux, disposed along an axial direction of the rotary member and opposite the rotary member, to heat by induction the heat generation layer; a first demagnetizing coil layered on the excitation coil and generating magnetic flux in a direction reverse to and cancel the magnetic flux that the excitation coil generates; a sheet size detector to obtain a size of a recording sheet on which an image is to be formed by passing through the rotary member; and a drive controller to control driving of the first demagnetizing coil. The drive controller drives the first demagnetizing coil after information including the sheet size information has been obtained.

Fixing device and image forming apparatus

The toner includes a binder resin; a colorant; and a release agent. The first inter-particle force Fp(A) of the toner, which is measured under an environmental condition of 23&#xb0; C. and 60% RH after the toner is pressed for 1 minute at 25&#xb0; C. under a compression stress of 15 kg/cm, is from 1.0&#xd7;10(N) to 1.0&#xd7;10(N). The difference (Fp(B)&#x2212;Fp(A)) between the second inter-particle force Fp(B) of the toner, which is measured under the environmental condition of 23&#xb0; C. and 60% RH after the toner is pressed for 1 minute at 50&#xb0; C. under a compression stress of 15 kg/cm, and the first inter-particle force Fp(A) is 0 (N) to 1.0&#xd7;10(N).

Toner, method for preparing the toner, and image forming method using the toner

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Kanagawa, Japan

Naoko Morisawa