Mita Industrial Co., Ltd.

Toshimitsu Ikeda

Nobuyasu Honda

Toshikazu Matsui

Tatsuo Aizawa

Shoji Matsumoto

Nobuhiko Kozuka

Hitoshi Nishihama

Toshiro Yamakawa

Akira Fushida

Tetsuya Nakano

Yasushi Kamezaki

Takashi Teshima

Hideo Fukuda

Nobuyoshi Hisao

Kaoru Sakata

Kenji Takahashi

Disclosed is a magnetic brush development method comprising supplying a two-component type developer comprising a mixture of magnetic carrier particles with toner particles chargeable by friction with the magnetic carrier particles onto a developing sleeve consisting of a non-magnetic sleeve having a magnet installed therein to form a magnetic brush of the developer, and bringing the magnetic brush in sliding contact with the surface of a photosensitive material having an electrostatic latent image formed thereon in the state where a bias voltage is applied between the photosensitive material and the sleeve, whereby a toner image corresponding to the electrostatic latent image is formed, wherein the two-component type developer comprises a ferrite carrier and electroscopic toner particles at a weight ratio of from 4/1 to 20/1.

Magnetic brush development method

Disclosed is a pressure-fixing toner for the electrophotography, which comprises electroscopic particles having an indeterminate shape and comprising as a pressure-fixing binder component a composite binder component comprising a wax component and a resin component composed mainly of a styrene-acrylic copolymer at a weight ratio of from 54/46 to 20/80, wherein the wax component is present in the form of spherical particles having a particle size smaller than 10 microns in a continuous phase of the resin component.

Pressure-fixing toner for electrophotography and process for preparation

Disclosed is a method for developing electrostatic latent images, which comprises frictionally contacting the surface of a substrate having an electrostatic latent image formed thereon with a magnetic brush of a developer formed on a developer-delivering sleeve having a magnet disposed therein, wherein a magnetic brush is formed on the sleeve with an earing promoting component comprising sintered ferrite particles having a particle size of 20 to 100 microns and a developer component comprising particles of a dispersion of a magnetic powder in a binder medium having a particle size of 5 to 50 microns.

Method for developing electrostatic latent images

Disclosed is a magnetic toner having an improved humidity dependency, which comprises as main ingredients a magnetic material composed of magnetite and a binder medium, wherein the water-soluble component content in the magnetite is lower than 0.15% by weight and the water content of the magnetite at a temperature of 20.degree. C. and a relative humidity of 60% is lower than 0.3% by weight. If this magnetic toner is used for developing an electrostatically charged image, a sharp and clear copy having a high image density with no fogging can be obtained even under a high humidity condition.

Magnetic toner having improved humidity dependency

Disclosed is a method of developing an electrostatic image by bringing an electrostatic image-carrying surface of a substrate into sliding contact with a magnetic brush of a developer formed on a developer-feeding sleeve having a magnet arranged in the interior thereof, wherein the magnetic brush is formed from an earing-promoting component comprising particles of a dispersion of a powder of a magnetic material in a resin, which have a relatively large diameter of 70 to 300 microns, and a developer component comprising particles of a dispersion of a powder of a magnetic material in a binder medium, which have a relatively small diameter of 5 to 50 microns.

Method of developing electrostatic image with magnetic brush ear promoter

In a method and apparatus for developing a latent electrostatic image formed on the surface of an image-bearing material by applying a powdery developer thereto, which includes magnetically retaining a layer of a relatively conductive one-component developer having a resistivity of not more than 10.sup.13 ohms-cm on the surface of a developer-retaining member, and bringing the developer on the surface of the developer-retaining member into contact with the surface of the image bearing material, the improvement wherein the developer-retaining member has a resistance, measured by a point-plane resistance measuring method in an environment kept at a temperature of 20.degree. C. and a humidity of 50%, of from 3.times.10.sup.7 ohms to 1.times.10.sup.10 ohms. The improved method makes possible good development without causing a background fog or a tail effect.

Method and apparatus for developing latent electrostatic images

Disclosed is a dry developer for an electrostatic image, which comprises molded particles of a dispersion of a binder medium, a wax and a pigment, wherein a combination or partial reaction product of (A) a copolymer of an olefin with a polar group-containing, ethylenically unsaturated monomer and (B) a metal alkoxide of aluminum or titanium is incorporated as a crosslinking agent into said molded particles. In this dry developer, the mutual dispersibility of the respective developer components is highly improved, and the developer particles are uniform and homogeneous in the composition. This dry developer for an electrostatic image is prepared by a process which comprises kneading a mixture of a binder resin, a wax and a pigment at a temperature higher than the softening points of the binder resin and wax and molding the kneaded composition into fine particles, wherein prior to, simultaneously with or after addition of the pigment, a combination or partial reaction product of (A) a copolymer of an olefin with a polar group-containing, ethylenically unsaturated monomer and (B) a metal alkoxide of aluminum or titanium is incorporated into the binder resin and wax and the composition is reacted in the molten state.

Dry developer for electrostatic image with Al or Ti alkoxide

A composite magnetic developer having a self-friction-chargeability is in the form of fixable magnetic particles having a particle size of 5 to 30 microns and comprising a finely divided magnetic material dispersed in a binder medium which shows an adhesiveness under application of heat and pressure, in which the fixable magnetic particles contain fine particles of a magnetic material embedded in the surface of the fixable magnetic particles in an amount of 1 to 10% by weight based on the fixable magnetic particles and fine particles of a magnetic material adhering to the surface of the fixable magnetic particles without being embedded therein in an amount of 1 to 20% by weight based on the fixable magnetic particles. This developer provides a sharp and clear transfer image having a high density without fogging or edge effects on a transfer sheet having a low electric resistance such as a plain paper. When this developer is used for development of electrostatic latent images, any particular charging operation need not be performed and any carrier need not be used. Even if this developer is used repeatedly for the copying operation, the composition is not substantially changed and good developing characteristics are retained.

Magnetic developer and process for preparation thereof

An electrophotograhic copying process forms an electrostatic latent image on the surface of a photosensitive member, developes the image by applying a monocomponent developer to the latent image to form a toner image, transfers the thus formed toner image by contacting a receptor sheet with the photosensitive member to transfer the toner image to the surface of the receptor sheet, fixes the toner image onto the surface of the receptor sheet, eliminates electrostatic charge from the photosensitive member by irradiating the surface of the photosensitive member with an electrostatic eliminating lamp after the toner image has been transferred to the receptor sheet, and cleans the surface of the photosensitive member by removing the developer remaining on the surface thereof. A developer-holding member holds the same kind of developer as used in the developing step on the surface of said developer-holding member by a stationary magnet disposed within the developer-holding member, and the surface of the developer-holding member is moved in a direction opposite to the direction of movement of the surface of the photosensitive member while contacting the two surfaces through the layer of the developer to mechanically brush the surface of the photosensitive member by the layer of the developer. The magnet having a plurality of poles, and the magnetic pole which is located closest to a position at which the surface of the developer-holding member is closest to the surface of the photosensitive member is downstream in the rotation direction of the developer-holding member by a certain angle with respect to the position at which the two surfaces are closest to each other.

Cleaning process for an electrostatic copying apparatus

An electrostatic copying apparatus has a housing having at its top surface a transparent plate on which to place an original to be copied, a rotary drum disposed within the housing and having a photosensitive member on its surface, a charging, a developing, a transferring and a cleaning mechanism which are successively arranged around the rotary drum in the moving direction of its surface, an optical system for projecting the image of the original onto the surface of the rotary drum between the charging mechanism and the developing mechanism, and a receptor sheet conveying system for transporting a receptor sheet through a transfer station defined between the surface of the rotary drum and the transferring mechanism. A support is mounted on the housing so that it is slidable in the forward and rearward directions between its operating position within the housing and its pulled-out position ahead of the housing, and the rotary drum and the developing device are mounted on the support so that they can be separately and independently detached from the support. An electrostatic copying process can be efficiently practiced by using this apparatus.

Electrostatic copying process and apparatus

An electrostatic copying apparatus has a housing having at its top surface a transparent plate on which to place an original to be copied, a rotary drum disposed within the housing and having a photosensitive member on its surface, a charging, a developing, a transferring and a cleaning mechanism which are successively arranged around the rotary drum in the moving direction of its surface, an optical system for projecting the image of the original onto the surface of the rotary drum between the charging means and the developing means, and a receptor sheet conveying system for transferring a receptor sheet through a transfer station defined between the surface of the rotary drum and the transferring mechanism: A support is mounted on the housing so that it is slidable in the forward and rearward directions between its operating position within the housing and its pulled-out position ahead of the housing, and the rotary drum and the developing device are mounted on the support so that they can be separately and independently detached from the support. An electrostatic copying process can be efficiently practiced by using this apparatus.

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Himeji, Japan

Toshimitsu Ikeda