Mita Industrial Co., Ltd.

Yumiko Sano

Nobuhiro Miyakawa

Masatomi Funato

Kazuhito Takaoka

Akiyoshi Urano

Teruaki Higashiguti

Kazushige Inoue

Masatoshi Uehara

Teruyo Morimoto

Eiji Nimura

Mamoru Kato

Teruaki Higashiguchi

Tatsuo Maeda

Kouji Maekawa

Seiji Kado

Syoji Nakagama

Yosinobu Umetani

Uehara Masatoshi

Yuji Tomii

Hiroyuki Yamaji

A black photoconductive toner having sensitivity to light in the wavelength range of semiconductor lasers, the toner containing a resinous binder, photoconductive material, a sensitizer, and a perylene black pigment or yellow, magenta, or cyan quinone dyes.

Black photoconductive toner having sensitivity to light in the

A photoconductive toner of the present invention contains a resin binder, zinc oxide, and a dye for sensitization of the zinc oxide, the sensitizer dye being represented by the following formula (1): ##STR1## wherein, X.sup.1 to X.sup.8 represent hydrogen or methoxy groups with a proviso that at least one of X.sup.1 to X.sup.8 represents a methoxy group, R.sup.1 and R.sup.2 are independently alkyl groups or derivatives thereof, and n is an integer. A photoconductive toner of the present invention satisfies requirements for both sensitivity and coloration, and, moreover, possesses high photosensitivity in the laser wavelength region as compared with conventional toners.

Photoconductive toner comprising a sensitizer dye

An image-forming method including the steps of forming a thin layer of a photosensitive toner charged to have a given polarity on a conductive drum, exposing said thin layer to light according to image information, and pressing a roller-type electrode against said toner thin layer through a transfer material after said exposing step to transfer a part of said photosensitive toner onto said transfer material. The method further includes the step of continuing contact between said conductive drum and said transfer material after said transfer material passes said roller-type electrode. Accordingly, a sharp toner image having a high density can be formed without the generation of fog.

Electrophotographic image-forming method

An image-forming method including the steps of forming a thin layer of a photosensitive toner charged to have a given polarity on a conductive drum, exposing the thin layer to light according to image information, and transferring a part of the photosensitive toner onto a transfer material. The transferring step includes contacting the transfer material with the thin layer after the exposing step as applying a pressure to the transfer material, and irradiating a corona ion from a back side of the transfer material to the thin layer by using a corona charger. Thus, the transfer material is maintained in pressure contact with the thin layer of the toner during the transferring step, thereby improving a transfer efficiency of the toner to the transfer material to obtain a satisfactory image having a high density and no void.

Disclosed is a photosensitive toner sensitive to light with wavelengths in the range of 600 to 700 nm, which includes zinc oxide, a sensitizing dye, and a resinous binder. The sensitizing dye is a cyanine dye which is represented by the following general formula (I): ##STR1## R is CH.sub.3, C.sub.2 H.sub.5, n-C.sub.4 H.sub.9, n-C.sub.7 H.sub.15, CH.sub.2 COOH, C.sub.2 H.sub.4 COOH or allyl, and X is I, Cl, Br, NO.sub.3 or tolylsulfonyl.

Cyan-colored photosensitive toner containing zinc oxide

Disclosed is an image forming apparatus in which photosensitive toner remaining on an electrically-conductive drum after the formation of an image is collected and then used again for the subsequent process of forming an image. The apparatus comprises a toner storage unit including a toner feed system and a toner collecting system both disposed within a single housing. The toner feed system feeds toner onto an electrically-conductive drum for the formation of an image. The toner collecting system includes a blade for removing the toner remaining on the conductive drum after the formation of the image, and also includes a transporting paddle or a feeder for delivering the removed toner back to the toner feed system, the toner then being supplied again onto the electrically-conductive drum for the subsequent image-forming process.

Image forming apparatus using photosensitive toner

Disclosed in an image-forming process which comprises arranging two electrode surfaces, at least one having a curvature face and at least the other being transparent, to confront each other, forming a layer of a photosensitive toner on one of the electrode surfaces, applying a bias voltage so that the polarity of the toner layer-supporting electrode surface is the same as the polarity of charges on the toner and the polarity of the confronting electrode surface is reverse to the polarity of charges on the toner, irradiating the toner layer with light at a part where both the electrode surfaces are contacted with each other through the photosensitive toner layer, and transferring the unexposed toner toward the confronting electrode surface.

Image-forming process using photosensitive toner

Disclosed is a photoconductive toner comprising as a main component a photoconductive substance dissolved or dispersed in a binder resin medium, wherein when the photoconductive substance is a p-type semiconductor, it is combined with a binder resin having a positive tribochargeability and when the photoconductive substance is an n-type semiconductor, it is combined with a binder resin having a negative tribochargeability.

Photoconductive toner

A method for the formation of images comprising: (1) feeding a photoconductive toner, having a particle diameter of on the average 6 .mu.m or less, to a conductive substrate to form a toner layer of 1 to 8 layers on said conductive substrate, (2) uniformly charging said toner layer, and (3) exposing said toner layer to form an electrostatic latent image thereon corresponding to the original.

Method for the formation of electrophotographic images

A photosensitive material for electrophotography, which comprises an electroconductive substrate and a photosensitive layer formed on the substrate. The photosensitive layer comprising a charge transfer medium and a charge-generating pigment dispersed in the mediums. The photosensitive layer contains as the matrix resin a thermoplastic polyester consisting essentially of recurring units represented by the following general formula: ##STR1## wherein R.sup.1 stands for a phenylene group or an ethylene group, R.sup.2 stands for a group represented by the formula ##STR2## R.sup.3 stands for a direct bond or a divalent bridging atom or group, and the ring A may have a substituent not participating in the reaction. In another embodiment a photosensitive material for electrophotography includes an electroconductive substrate, a photoconductive organic pigment-containing, charge-generating layer formed on the substrate and a charge transfer layer formed on the charge-generating layer, wherein the charge transfer layer contains as the matrix resin the above-mentioned thermoplastic polyester. These thermoplastic polyesters provide improvements in adhesion to the substrate, surface hardness and abrasion resistance.

Photosensitive material for electrophotography

An electrophotographic method for the formation of two-colored images comprising: (1) uniformly charging the surface of a photoreceptor having a conductive substance and a photoconductive layer formed on the conductive substance, said photoconductive layer being sensitive to a first color, (2) exposing a two-colored original, to form on said photoconductive layer an electrostatic latent image, which corresponds to a second color region in the original, with the same polarity as the electric charges on the surface of said photoconductive layer, (3) subjecting the surface of said photoreceptor to a reversal development treatment by the use of a photoconductive color toner charged with the same polarity as the electric charges constituting said electrostatic latent image, to develop the non-charged region with the photoconductive color toner, (4) subjecting said electrostatic latent image to a normal development treatment by the use of an insulative toner having a color different from the color of said photoconductive color toner, and (5) charging the color toners on said photoconductive layer with a different polarity from the charging polarity in process (1) and simultaneously exposing said original through a filter shielding against said first color, thereby providing a practical method for the formation of a desired two colored distinct image corresponding to the original.

Electrophotographic method for the formation of two-colored images

Disclosed is a photosensitive material for electrophotography comprising an organic polymeric photoconductive material and a thermoplastic polyester composed mainly of recurring units represented by the general formula ##STR1## wherein R.sup.1 represents a phenylene, ethylene or vinylene group, R.sup.2 represents a group of the formula ##STR2## R.sup.3 represents a direct bond or a divalent bridging atom or group, and the ring A may have a substituent inert to the polyester-forming reaction, provided that R.sup.1 and R.sup.2 are selected such that one of them contains an aromatic ring and the other does not.

Electrophotographic photosensitive material with polyester binder

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.

Disclosed is an electrophotographic photosensitive material comprising a photosensitive layer containing a tris-azo pigment represented by the following formula: ##STR1## wherein the ring A.sub.1 and A.sub.2 may have a halogen atom, an alkyl group or alkoxy group as a substituent at the ortho-position to the azo group, Z stands for a benzene ring, naphthalene ring, indole ring, carbazole ring or benzofuran ring fused to the benzene ring B, and R stands for an unsubstituted or substituted phenyl, naphthyl or heterocyclic group. This photosensitive material has a high sensitivity to rays in a broad wavelength region and is excellent in the resistance in the printing operation.

Growing community of inventors

Ibaraki, Japan

Yumiko Sano