Mita Industrial Co., Ltd.

Teruaki Higashiguchi

Nobuhiro Miyakawa

Koji Yano

Kazuo Yamamoto

Kaname Nakatani

Yoshinobu Kawakami

Junko Mizuno

Yumiko Sano

Shoji Matsumoto

Masanori Matsuda

Masatomi Funato

Eiji Goto

Kouji Maekawa

Akinori Nishida

Takeshi Hori

Syoji Nakagama

Tomiyasu Matsuda

Tomomi Edo

Isao Iwagawa

An electrifying method which uses a electrifying a material wherein the contact-type electrifying member comprises a flexible and electrically conducting endless sheet and a brush which supports said endless sheet and imparts a pressing force thereto at a position where said endless sheet is in contact with the material to be electrified, said endless sheet which is impressed with an electrification voltage is driven or is moved at a speed which is substantially in synchronism with the material to be electrified, and the brush and the endless sheet are maintained at dissimilar speeds. This method makes it possible that homogeneously and uniformly electrifying a material to be electrified such as a photosensitive material or a like material without causing it to be damaged or worn out, even when the material electrifying member is rugged or even when a foreign matter is adhered on the surface of the photosensitive material, and a toner filming is not formed on the surface of the photosensitive material, and maintaining a uniformly contacting state between the electrifying member and the photosensitive material even with a relatively small force, as a result, accomplishes homogeneous electrification while preventing the photosensitive material from being worn out.

Electrifying method and electrifying apparatus used therefor

The present invention relates to a developing process for forming a high-quality image in the electrophotography. In this developing process, a two-component type developer is used and the moving direction of a developing sleeve is the same as the moving direction of a photosensitive material drum at the position of the sliding contact of the photosensitive material drum with a magnetic brush of the developer. In carrying out this forward direction sliding contact developing process, by setting the angle .theta. of a fixed main developing pole to the direction reverse to the moving direction of the sleeve from the line connecting the centers of the drum and sleeve and the drum/sleeve diameter ratio within certain specific ranges, the reproducibility of fine lines and the image density can be simultaneously improved very effectively in a well-balanced state, and a toner image having a high quality can be formed.

Developing process for forming image having high quality

An optimum image can be obtained by carrying out the development while using a two-component type developer comprising an electroscopic toner and a magnetic carrier and having a specific toner concentration and maintaining the peripheral speed ratio of the magnet sleeve to the photosensitive material drum within a certain range according to the average particle size, saturation magnetization and electric resistance value of the magnetic carrier.

Development process for formation of high-quality image

An optimum image can be obtained by carrying out the development while using a two-component type developer comprising an electroscopic toner and a magnetic carrier and maintaining the peripheral speed ratio of the magnet sleeve to the photosensitive material drum within a certain range according to the average particle size and saturation magnetization of the magnetic carrier.

Magnetic brush development process

In an electrophotographic developing method using a magnetic brush consisting of a mixture of magnetic carrier and an electroscopic toner, development is carried out at a toner concentration (Ct. %) in the mixture, which satisfies the requirement represented by the following formula: ##EQU1## wherein Sc stands for the specific surface area (cm.sup.2 /g) of the carrier, St stands for the specific surface area (cm.sup.2 /g) of the toner, and k is a number of from 0.90 to 1.14. A toner image having a high quality can be obtained according to this method.

Method for developing electrostatic images using magnetic brush

An optimum image can be obtained by carrying out the development while using a two-component type developer comprising an electroscopic toner and a magnetic carrier and maintaining the peripheral speed ratio of the magnet sleeve to the photosensitive material drum within a certain range according to the average particle size and saturation magnetization of the magnetic carrier and the dynamic friction coefficient of the magnetic brush.

A two-component electrophotographic developer for use in developing a latent electrostatic image of a low potential. The developer is composed of a mixture of a magnetic carrier of spherical sintered ferrite particles having raised and depressed portions attributed to the primary particles on their surface, a median size of from 30 to 50 micrometers, an apparent density of less than 2.6 g/cc and an electric resistance, measured in the form of a magnetic brush, of from 6.times.10.sup.4 to 2.5.times.10.sup.6 ohms and chargeable toner particles having a volume inherent resistivity of at least 1.times.10.sup.13 ohms-cm and a specific inductive capacity of from 4 to 6. In a preferred embodiment, the chargeable toner particles have a median size of from 10 to 14 micrometers and are substantially free from particles having a particle diameter of not more than 5 micrometers. The developer can give an image of a high density, a high resolution and excellent gradation without brush marks.

Two-component electrophotographic developer with magnetic carrier

Disclosed is an electrophotographic apparatus comprising a photosensitive drum comprising an amorphous silicon type photoconductor layer formed on an electroconductive substrate, a main charging mechanism for charging the surface of the drum with charges having a predetermined polarity, an imagewise exposure mechanism for forming an electrostatic image corresponding to an image of an original on the surface of the drum, a toner development mechanism for forming a toner image corresponding to the electrostatic image, a toner image transfer mechanism for transferring the toner image formed on the surface of the photosensitive drum to a predetermined paper sheet, a toner cleaning mechanism for removing the residual toner adhering to the surface of the photosensitive drum and a fixing mechanism for fixing the transferred toner image to said paper sheet, wherein a heating mechanism is arranged to heat the surface of the photosensitive drum at a temperature of 30.degree. to 40.degree. C. The problem of the flow of an image inherent to the use of an amorphous silicon type photoconductive layer is effectively solved if this electrophotographic apparatus is employed.

Electrophotographic apparatus comprising photosensitive layer of

In a copying machine comprising a photosensitive drum having an amorphous silicon type photoconductive layer, if an image of an original is focussed on the photoconductive layer with a light having a wavelength shorter than 600 nm, the light fatigue of the amorphous silicon photoconductive layer is prevented, and the image memory phenomenon owing to the light fatigue is effectively obviated.

Copying machine having reduced image memory

A toner for electrophotography, comprising an azoic pigment having a silica core as a coloring component, said azoic pigment comprising a core of a fine powder of silica and a coating of a mono- or polyazoic dye chemically bound to the surface of the silica core through an aminosilane coupling agent.

Toner for electrophotography comprising azoic pigment having silica core

An azoic pigment having a silica core comprising a core of a fine powder of silica having a particle diameter of not more than 10 microns and a coating of a mono- or polyazoic dye chemically bound to the surface of the silica core through an aminosilane coupling agent.

Azoic pigments having a silica core

Disclosed is a photosensitive material for electrophotography containing a pentakisazo pigment of the following formula: ##STR1## wherein the rings A.sub.1 and A.sub.2 may have halogen atoms, alkyl groups or alkoxy groups as substituents at the ortho-positions to the azo groups, the ring B may have a halogen atom, an alkyl group or an alkoxy group as a substituent or may contain the ring Z.sub.1, Z.sub.1 which is an aromatic or hetero ring fused to the benzene ring B, and Y stands for a group of the following formula: ##STR2## in which Z.sub.2 stands for an aromatic ring or a hetero ring, Ar.sub.1 stands for an aromatic ring or a hetero ring, Ar.sub.2 and Ar.sub.3 stand for an aromatic ring, R.sub.0 stands for a hydrogen atom, a lower alkyl group or a phenyl group, R.sub.1 stands for a lower alkyl group, a carboxyl group or an ester thereof, and R.sub.2 and R.sub.3 stand for a hydrogen atom, a lower alkyl group, a phenyl group or a substituted derivative thereof.

Photosensitive material for electrophotography containing photosensitive

Electrophotographic photosensitive material comprising an electroconductive substrate and a layer of a photoconductive composition composed of a dispersion of a charge generating pigment in a charge transporting medium, which is formed on the electroconductive substrate, wherein said photoconductive composition contains an N,N-di-substituted-carbamic acid salt in an amount of 20 to 200% by weight based on the charge generating pigment. This electrophotographic electrophotosensitive material has excellent ozone resistance and shows a high initial charge retention ratio and sensitivity retention ratio when the cycle of charging and light exposure is repeated many times.

Electrophotographic photosensitive material with ozone inhibitor

Disclosed is a photosensitive material for electrophotography, which comprises a photosensitive layer containing a disazo pigment represented by the following formula: ##STR1## wherein R.sub.1 stands for a lower alkyl group or a lower alkoxy group, n is a number of zero, 1 or 2, R.sub.2 stands for a lower alkyl group, a lower alkoxy group, a di-lower-alkylamino group, a nitro group or a halogen atom, m is a number of zero, 1 or 2, Z stands for a benzene ring or a naphthalene ring, and Y stands for a group represented by the following formula: ##STR2## in which B stands for a benzene, naphthalene, indole, carbazole or benzofuran ring or a substitution product thereof, which is fused to the benzene ring, Ar.sub.1 and Ar.sub.2 stand for a benzene ring, a naphthalene ring, a dibenzofuran ring or a substitution product thereof, R.sub.3 stands for a lower alkyl group, a carboxyl group or a carboxyl ester group, and R.sub.4 stands for a hydrogen atom, a lower alkyl group, a phenyl group or a substituted phenyl group.

Electrophotographic photosensitive material

Disclosed is a photosensitive material for electrophotography, which comprises a photosensitive layer containing a tetrakis-azo pigment represented by the following formula: ##STR1## wherein X.sub.1 stands for a lower alkyl group, a lower alkoxy group or a halogen atom, X.sub.2 and X.sub.3 stand for a lower alkyl group, a lower alkoxy group, a halogen atom or a hydrogen atom, and Y stands for a group represented by the following group: ##STR2## in which Z stands for an aromatic ring such as a benzene or naphthalene ring, a substitution product thereof, a hetero ring such as an indole, carbazole or benzofuran ring, or substitution product thereof, Ar.sub.1 stands for an aromatic ring such as a benzene or naphthalene ring, a substitution product thereof, a hetero ring such as a dibenzofuran ring, or a substitution product thereof, Ar.sub.2 and Ar.sub.3 stand for an aromatic ring such as a benzene or naphthalene ring or a substitution product thereof, R.sub.1 stands for a lower alkyl group, a carboxyl group or an ester thereof, and R.sub.2 and R.sub.3 stand for a hydrogen atom, a lower alkyl group, a phenyl group or a substitution product thereof.

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Tokyo, Japan

Teruaki Higashiguchi