Hitachi, Ltd.

Hitachi Koki Co., Ltd.

Hitachi Printing Solutions, Ltd.

Ricoh Printing Systems, Ltd.

Hitachi Metals, Ltd.

Ricoh Company, Ltd.

Hitachi Chemical Company, Ltd.

Dainichiseika Color & Chemicals Mfg. Co., Ltd.

Hitachi Metals Co., Ltd.

Tsuneaki Kawanishi

Ryuuichi Shimizu

Teruaki Mitsuya

Toshiya Satoh

Takashi Suzuki

Hisao Okada

Masayasu Anzai

Shigenori Yaguchi

Nobuyoshi Hoshi

Junji Kobayashi

Akio Mukoh

Hirosada Morishita

Yasuki Mori

Masayoshi Ishii

Shigeo Suzuki

Katsuya Kawai

Hiroyoshi Matsumoto

Ryuichi Shimizu

Koji Kato

Keisuke Kubota

Akio Tsujita

Tomonari Hokkyo

Tadahiro Kaneko

Natsuki Kuribayashi

Yutaka Ito

Sukekazu Aratani

Toshikazu Narahara

Koji Noguchi

Noriyuki Kinjo

Hiroyoshi Kokaku

Yoshitaka Fujinuma

Hiroyuki Mabuchi

Akira Kageyama

Takayuki Nakakawaji

Yasuo Takuma

Atsushi Kakuta

Akira Shimada

Toshiro Saito

Katuo Sugawara

Masayuki Ainoya

Shigeki Komatsuzaki

Katsumi Kumada

Tsutomu Iimura

Tsutomu Nakagawa

Yuichiro Suzuki

Katsuhiko Suzuki

Osamu Isoo

Yasuo Katsuya

Hirobumi Ouchi

Akira Hosoya

Masami Ishikawa

Shigeo Hosaka

Mitsuoshi Shoji

Tooru Hosoda

An electrophotographic apparatus includes: a photoconductor; and two developing rollers facing the photoconductor. A developer fed out from between the two developing rollers is supplied to the photoconductor by the two developing rollers to form a toner image on the photoconductor. The developer includes a carrier having a volume-average particle size smaller than 70 &#x3bc;m and a volume resistivity not lower than 10&#x3a9;&#xb7;cm. A volume ratio of the carrier in a facing portion between the photoconductor and the developing rollers is not lower than 30% and not higher than 46%.

Developing device and electrophotographic apparatus using the same

The invention provides an electrostatic charge image developing toner containing a fixing resin and a wax, characterized in that in a DSC curve measured by a differential scanning calorimeter for the wax, a maximum endothermic peak of endothermic peaks at temperature up is less than 70&#xb0; C., on-set temperature attributable to the maximum endothermic peak is above 50&#xb0; C., and lowest on-set temperature of on-set temperatures attributable to endothermic peaks except the maximum endothermic peak is in a range of from 30&#xb0; C. to 40&#xb0; C.

Electrostatic charge image developing toner, and developer, image forming apparatus and image forming method using the same toner

In an image forming method, when viewed from the moving direction of a photosensitive bodythere is disposed, on the upstream side, a first developing rolleropposed to and adjacent to the photosensitive bodyand rotatable in the opposite direction to the photosensitive bodywhile the peripheral speed ratio of the rollerto the photosensitive bodyranges from 0.8 to 2.0; on the downstream side of the rollerthere is disposed a second developing rollerrotatable in the same direction to the photosensitive bodywhile the peripheral speed ratio of the rollerto the photosensitive bodyranges from 1.05 to 2.0; and the shape coefficient SFof the toners of two-component developing agent ranges from 120 to 170, while the shape coefficient SFranges from 110 to 130.

Image forming method and image forming apparatus

An electrophotographic toner containing: a fixing resin, a colorant, and wax. The wax at least contains hydrocarbon wax having a number-average molecular weight of not higher than 600, and polyethylene wax having a number-average molecular weight of not higher than 600, a melting viscosity of lower than 15 mPa&#xb7;s at 140&#xb0; C. and a crystallinity of lower than 95%. A ratio of the hydrocarbon wax to the polyethylene wax is in a range of from 1:10 to 2:1. A maximum of absorption peaks in a heat-up time absorption calorie curve in a DSC curve of the toner measured by a differential scanning calorimeter is at a temperature not higher than 75&#xb0; C. An onset temperature in absorption of heat is not higher than 65&#xb0; C.

Electrophotographic toner and image-forming system

A transfer member transporting section is disposed so as to bring a tip end of a transfer member into contact with a peripheral face of a transfer rotary member before the tip end of the transfer member enters a nip area. A bias power supply has a polarity inverting function of, during a period from a timing when the tip end of the transfer member is brought into contact with the transfer rotary member by the transfer member transporting section, to that when the tip end of the transfer member enters the nip area, applying a voltage of a polarity which is identical with that of a toner, to the transfer rotary member, and after the tip end of the transfer member enters the nip area, applying a voltage of a polarity which is opposite to that of the toner, to the transfer rotary member.

Image forming apparatus with transfer bias inverting function

A developing unit in an electro-photographic apparatus such as a printer, a facsimile and a copier for actualizing an image employing colored particles such as toner, and more particularly to a developing unit for forming a toner image on the surface of a photosensitive body. The developing unit includes a plurality of developing rollers each having a core and a sleeve. The sleeve accommodates the core. The plurality of developing rollers include a first developing roller and a second developing roller. The sleeve for the first developing roller is rotated to move in the same direction as a moving direction of the surface of the photosensitive body. The sleeve for the second developing roller is rotated to move in an opposite direction to the moving direction of the surface of the photosensitive body. The core of only one of the plurality of developing rollers is driven in rotation while the other core is fixed. Alternatively, a magnetic pole of one of the developing rollers is placed at an opposing position where the developing rollers mutually oppose while an intermediate portion between two poles of the second developer roller is placed at the opposing position.

Electro-photographic developing unit

Electrostatic image developing toner includes fixing resin; and wax. The wax is hydrocarbon-based wax. The wax is containing, as its constitutional components, first wax and second wax. The first wax is higher than 1.5 in ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), lower than 10 mPa&middot;s in melt viscosity at 140&deg; C. and higher than 75% and not higher than 85% in degree of crystallinity. The second wax is not higher than 1.5 in ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), lower than 10 mPa&middot;s in melt viscosity at 140&deg; C. and higher than 85% and not higher than 95% in degree of crystallinity.

Electrostatic image developing toner and image forming method

Electrostatic charge developing toner contains at least fixing resin, a coloring agent and wax. Wax having number average molecular weight of not higher than 600 is contained as a component of the wax. A volume average particle size of the toner is in a range of from 5 &mgr;m to 10 &mgr;m. Toner particles each having a particle size of not larger than 4 &mgr;m are contained by 10% or lower by number of the total number of toner particles.

Electrostatic charge developing toner and image forming method using the same

An electrostatic recording apparatus including: an image carrier including an organic photoconductive photoreceptor having an abrasion-resisting outermost periphery; an exposing unit which exposes the image carrier to form an electrostatic latent image thereon; a developing unit which contains a toner and develops the electrostatic latent image with the toner to form a toner image; a transferring unit which transfers the toner image thus formed onto a recording medium; and a fixing unit which fixes the transferred toner image on said recording medium, wherein the toner contained in said developing unit includes an electrically conductive fine powder attached to the surface thereof.

Electrostatic recording apparatus

A uniform image is obtained by matching the sliding friction force, the moving speed and the developing agent in a developing region of two developing rollers and an electric characteristic of a photosensitive body used for image development. Two developing rollers rotating in directions opposite to each other are used, the moving direction of the first developing roller being opposite to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the first developing roller to a circumferential speed of the photosensitive body is within a rage of 0.5 to 2.5; and the moving direction of the second developing roller is equal to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the second developing roller to a circumferential speed of the photosensitive body is within a range of 1.5 to 3.5. A ratio of the sliding friction force between a magnetic brush for developing agent and the photosensitive body formed in the first developing roller and the sliding friction force between a magnetic brush for developing agent and the photosensitive body formed in the second developing roller is within a range of 0.9 to 2.1.

Electrophotographic apparatus

A toner for recording electrostatic image having a volume-average particle diameter of from 6 to 10 .mu.m, which exhibits a compression stress of from 50 to 500 kgf/cm.sup.2 at the middle temperature between room temperature and the glass transition temperature of the toner, and a compression stress of from 0.2 to 10 kgf/cm.sup.2 at the middle temperature intermediate between the glass transition temperature and the softening temperature of the toner.

Toner for recording electrostatic image and electrostatic recording

In an image forming apparatus forming an electrostatic latent image on a surface of a photosensitive body by exposing the charged photosensitive body, developing the latent image using a toner to form a toner image, transferring the toner image to a image holding body, and erasing the remaining charge on the surface of the photosensitive body after completion of the transferring, the photosensitive body is formed of a base material consisting of As.sub.2 Se.sub.3 or a-Si, and wherein the wavelength .lambda..sub.0 of the writing light used for the exposure is limited to a wavelength not larger than 780 nm, the wavelength .lambda..sub.1 of charge erasing light used for the charge erasing is limited to a wavelength smaller than 680 nm, and the time T.sub.1 from completion of the exposure to initiation of the development is limited within the range of 70 milliseconds to 300 milliseconds.

Image forming apparatus having a photosensitive body formed of a base

Image fixing device for use in electrophotographic apparatus, capable of suppressing gloss of fixed toner image, thus stably producing images of high quality and high level of fixing intensity over a long period of time. The fixing device is composed of a belt-type heating member and a pressing roller which are contacted with each other and rotate to form therebetween a nip through which a paper supporting unfixed toner image is passed to have the toner image fixed to the paper. The belt-type heating member comprises a metallic endless belt having fine irregularities formed on its surface and a surface layer made of a resin. The surface roughness of the fine irregularities ranges between 10 and 45 .mu.m, when measured by a ten-point averaging method.

Belt-type fixing device having an irregular surface contour

Image fixing device for use in electrophotographic apparatus, capable of suppressing gloss of fixed toner image, thus stably producing images of high quality and high level of fixing intensity over a long period of time. The fixing device has a fixing roller and a pressing roller which are contacted with each other and rotate to form therebetween a nip through which a paper supporting unfixed toner image is passed to have the toner image fixed to the paper. The fixing roller has a cylindrical core having fine irregularities formed on its surface and a surface layer made of a resin. The surface of the cylindrical core has a greater elastic modulus than that of the surface layer.

Fixing device for electrophotography and electrophotographic apparatus

Growing community of inventors

Ibaraki, Japan

Tsuneaki Kawanishi