Mita Industrial Co., Ltd.

Kyocera Mita Corporation

Nobuko Akiba

Fumio Sugai

Hirofumi Kawaguchi

Yuji Tanaka

Syunichi Matsumoto

Yasufumi Mizuta

Toshiyuki Fukami

Ichiro Yamazato

Hisakazu Uegaito

Yukimasa Watanabe

Hideki Okada

Kazunari Hamasaki

Hiroaki Iwasaki

Sakae Saito

Yasuyuki Hanatani

Yukikatsu Imanaka

Sakae Saitoh

The present invention relates to a positive charging single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer formed on the conductive layer, the photosensitive layer containing a phthalocyanine compound as an electric charge generating material, wherein a large half-life exposure between a half-life exposure on positive charging and a half-life exposure on negative charging is four times or less as much as that of the other half-life exposure., and a reversal development type digital image forming apparatus, comprising the electrophotosensitive material, said reversal development type digital image forming apparatus being provided with at least a main charging step, an exposure step, a developing step, a transferring step, a charge neutralizing step and a cleaning step in the forward direction of the electrophotosensitive material, characterized in that the voltage to be applied in the transferring step has a polarity reverse to that of the voltage to be applied in the charging step.

Single-layer type electrophotosensitive material and image forming apparatus using the same

Naphthoquinone derivative and electrophotosensitive material using the same

The present invention provides a naphthoquinone derivative represented by the general formula (1): ##STR1## wherein R.sup.1 represents an aryl group which may have a substituent; and R.sup.2 represents an alkylene group which may have a substituent, an arylene group which may have a substituent, etc.

Naphthoquinone derivative

The present invention provides a novel naphthoquinone derivative preferred as an electron transporting agent and an electrophotographic photosensitive material of high sensitivity which contains a novel naphtoquinone derivative having a general formula (1) ##STR1## wherein R.sup.1 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may contain a substituent, and R.sup.2 represents a hydrogen atom, an alkyl group which may have a substituent, a halogenated alkyl group, an aldehyde or a nitro group. The derivative is contained in a photosensitive layer of an electrophotographic photosensitive material as an electron transporting agent.

Naphthoquinone derivative and electrophotographic material using the

The present invention provides a novel tryptanthrine derivative represented by a general formula: ##STR1## wherein R.sup.1 is an oxygen atom, or group represented by a formula: ##STR2## wherein R.sup.2A and R.sup.2B are the same or different and indicate a hydrogen atom, a cyano group, an acyl group, an alkoxycarbonyl group or an alkyl group, provided that R.sup.2A and R.sup.2B are not hydrogen atoms simultaneously; and R.sup.3A, R.sup.3B, R.sup.3C, R.sup.3D, R.sup.4A, R.sup.4B, R.sup.4C and R.sup.4D are the same or different and indicate a hydrogen atom or an alkyl group which may have a substituent, provided that when R.sup.1 is an oxygen atom, any one of R.sup.3A through R.sup.4D is a cyano group. Such a tryptanthrine derivative has an excellent electron transport capability to be suitably used for the electrophotosensitive material.

Tryptanthrine compounds

The present invention provides a tryptoanthrinimine derivative represented by the general formula (Y): ##STR1## wherein R.sup.A to R.sup.M are as defined. Such a derivative of the general formula (Y) is superior in electron transferring capability. Accordingly, an electrophotosensitive material comprising a photosensitive layer containing this derivative (Y) is superior in sensitivity.

Tryptoanthrinimine derivative and electrophotosensitive material using

The present invention provides a novel trinitrofluorenonimine derivative represented by the general formula (1): ##STR1## wherein R.sup.0 is an alkyl group; and R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and indicate a hydrogen atom, an alkyl, an alkoxy, an aryl, an aralkyl, a halogen atom or an alkyl halide. This derivative is superior in electron transferring capability and compatibility with binding resin. Accordingly, an electrophotosensitive material comprising this derivative as an electron transferring material is superior in sensitivity.

Trinitrofluoroenonimine derivative and electrophotosensitive material

According to the present invention, there is provided a novel tryptoanthorine derivative represented by the formula: ##STR1## wherein R.sup.1a, R.sup.1b, R.sup.1c, R.sup.1d, R.sup.2a, R.sup.2b, R.sup.2c, and R.sup.2d are the same or different and indicate a hydrogen atom, an alkyl group or a halogenated alkyl group; provided that R.sup.1a, R.sup.1b, R.sub.1c and R.sup.1d do not indicate a hydrogen atom, simultaneously. Tryptoanthorine and a derivative thereof are suitably used for an electrophotosensitive material because of their excellent electron transferring capability.

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Osaka, Japan

Nobuko Akiba