Seiko Epson Corporation

Yoshihiro Nakashima

Yoichi Yamada

Tomoe Aruga

Tahei Ishiwatari

Hidenori Kin

Kazuhiro Ichikawa

Yukio Takayama

Yoshiro Koga

Takashi Suzuki

Hideki Okada

Hidetsugu Shimura

Takashi Hama

Takehiko Okamura

In a density control technique wherein a density of a toner image formed as a patch image is detected for performing density control based on the detected result, detection errors are decreased so as to properly set a density control factor. The density control factor is optimized based on a variation rate of the patch image densities against a varied density control factor. The detected results of the patch image densities are corrected based on information on an image carrier acquired before the formation of the patch images.

Image forming apparatus and image forming method for performing density control of toner images

Image forming apparatus and image method for forming toner images with optimized patch image density

A toner having a medium-resistance external additive, and an image forming apparatus which uses the toner. The medium-resistance external additive coating ratio of particles, of which mother particles have equivalent diameters smaller or larger than a diameter of a mother particle diameter, which is equal to the mean particle diameter of the toner, is set to be higher than a virtual reference curve in synchronous distribution of the particle diameters of synchronous medium-resistance external additive particles, relative to the diameters of mother particles. Further, the medium-resistance external additive coating ratios of particles in a range in which mother particles have diameters smaller than d , and in a range in which mother particles have diameters larger than d , are set to be higher than a virtual reference curve in synchronous distribution of the particle diameters of synchronous medium-resistance external additive particles relative to the diameters of mother particles.

Toner and image forming apparatus

A toner is characterized in that an external additive coating ratio of toner particles of which mother particles have equivalent particle diameters larger than the mean particle diameter of the toner is set to be lower than a virtual reference curve in synchronous distribution of the equivalent particle diameters of synchronous external additive particles relative to the equivalent particle diameters of mother particles, wherein assuming that the external additive coating ratio of a toner particle of which a mother particle has an equivalent particle diameter equal to the mean particle diameter of the toner is a reference value, the virtual reference curve is obtained to satisfy that the external additive coating ratio is constant at the reference value. An image forming apparatus utilizing the above-described toner is also contemplated.

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. The toner is mixed by conveying fins which have phases that are different in such a manner that the loads are uniform in rotation

Developing unit

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. A conveying fin is supported by the case so as to convey toner to the surface of the supply roller wherein the developing roller, the supply roller, and the conveying fin are sequentially disposed in a horizontal direction. The number of revolutions of the conveying fin per unit time is between {fraction (1/50)} and {fraction (1/20)} of the supply roller.

Developing unit having a conveying fin for loading a supply roller with toner

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. The toner contains a first and second additive having a specific covering ratio to the surface matrices in the toner.

Developing unit using specific developer composition

A plurality of developing units each includes a case which accommodates toner containing pigment, a developing roller, a supply roller formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller and a conveying fin. The developing roller, supply roller, and conveying fin for each developing unit are angularly arranged in a particular manner.

Image forming apparatus having a plurality of developing units

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller having chamfered ends and formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. Also a first sealing member is disposed on the side ends faces of the developing roller and supply roller so as to prevent leakage to the outside portion of the case. Further, a second sealing member in the form of a film is pressed against a lower surface of the developing roller in order to prevent leakage of toner, wherein a quantity &dgr; of displacement of the sealing member due to its abutment against the developing roller satisfies 0.1 mm<&dgr;<0.8 mm, and the thickness t of the second sealing member satisfies 50 &mgr;m<t<500 &mgr;m.

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, and a supply roller formed of an elastic material arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. A sealing member is disposed on the side ends of the developing roller and supply roller so as to prevent leakage to the outside portion of the case. A blade at least longer than the developing roller restrains the quantity of toner on the developing roller. The blade has a radius of curvature between 30 .mu.m and 150 .mu.m.

Developing unit having developing roller with restraining blade

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. Moreover, the percentage of open cells in the elastic supply roller is made to be 30% or higher and depth of engagement of the supply roller to the developing roller is made to 0.4 mm or smaller. The toner has shape factors SF-1 of 150 or smaller and SF-2 of 140 or smaller.

Developing unit using elastic supply roller

A developing unit of the present invention includes a case which accommodates toner containing pigment, a developing roller, a supply roller having chamfered ends and formed of an elastic member arranged to be pressed against a surface of the developing roller in such a manner as to supply toner to the surface of the developing roller. The side surfaces of the developing roller have a surface roughness of 0.5 .mu.m or smaller in Rmax.

Developing unit having developing roller with specific side surface

A developing device including a supply member pressingly contacted with a toner carrier, wherein the supply member has a hardness which greater than that of the toner carrier. The supply member is rotated in the same direction as the toner carrier to conduct the peeling and supply of toner. A plate spring-like regulation member is pressed against the toner carrier to charge the toner to a predetermined polarity and thin the toner into one or two layers. The toner carrier is made of a foam material.

Developing device

A developing device including a supply member pressingly contacted with a toner carrier having a hardness which is greater than that of the supply member and smaller than a predetermined hardness. The supply member is rotated in the same direction as the toner carrier to conduct the removing and supply of toner. A plate spring-like regulation member is pressed against the toner carrier to charge the toner to a predetermined polarity and thin the toner into one or two layers.

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Nagano-ken, Japan

Yoshihiro Nakashima