Ricoh Company, Ltd.

Junichiro Hashimoto

Kazuo Tsubuko

Taro Kimura

Tsuneo Kurotori

Shinichi Kuramoto

Manabu Mochizuki

Seiichi Miyakawa

Mitsuru Seto

Motoo Tasaka

Takashi Rokutanzono

Shinji Nousho

Makoto Okawara

Hideki Akiyoshi

Izumi Aiso

An electrophotographic photoconductor is composed of an electroconductive support, a photoconductive layer formed on the electroconductive support, and a protective layer formed on the photoconductive layer which is composed of a polyol curing-type urethane resin, and satisfies the condition of b/a.ltoreq.0.2, wherein a is the absorbance at 2920 cm.sup.- and b is the absorbance at 2260 cm.sup.-1 in an IR spectrum of the protective layer.

Electrophotographic photoconductor with overlayer of polyol-curing

This invention relates to a layered type photosensitive material for electrophotography, which comprises a charge generating layer and a charge transfer layer on an electroconductive substrate, characterized by containing a trivalent organic phosphite compound as an agent for preventing light-degradation.

Photosensitive material for electrophotography contains organic

A liquid developer for electrophotography is disclosed, which comprises a highly electrically insulating carrier liquid with a low dielectric constant and a colorant comprising a pigment component treated with a humic acid component selected from the group consisting of humic acid, a humic acid salt and a humic acid derivative, and then coated with a resin component, which colorant is dispersed in the highly electrically insulating carrier liquid.

Liquid developer for electrophotography

A liquid developer for use in electrophotography is disclosed which is prepared by dispersing a toner consisting essentially of a pigment or dye and a resin in a carrier liquid having a high insulating property and a low dielectric constant, wherein said resin is a nonaqueous dispersed resin obtained by effecting, in a nonaqueous solvent comprising an aliphatic hydrocarbon, the steps of:

Liquid developer for use in electrophotography

First and second sensors (37), (39) are provided in a developing tank (36) containing a liquid developer consisting of a liquid carrier or dispersant and toner particles dispersed in the carrier. The first sensor (37) measures the electrical resistivity of the developer whereas the second sensor (39) measures the optical transmissibility thereof. Additional toner is supplied into the developer to maintain the transmissivity at a value which is a predetermined function of the resistivity. The transmissibility value is reduced as the resistivity increases, thereby maintaining the copy image density constant. The first sensor (37) includes two electrodes immersed in the developer and an A.C. or D.C. voltage is applied thereacross. The current flow through the electrodes (37) and thereby the developer is measured to determine the resistivity of the developer. Where the applied voltage is D.C., an arrangement is provided to mechanically scrape accumulated developer off the electrodes (37) at intermittent intervals.

Electrostatic copying apparatus

A liquid developer for use in electrophotography which is prepared by making a carrier liquid comprising a non-aqueous solvent having a highly insulating property and a low dielectric constant contain a coloring agent and a resin dispersed therein, characterized in that said resin contains the following components (A) and (B):

Liquid electrostatic developer having pigment or dyestuff dispersed in a non-aqueous dispersion containing a graftcopolymer and at least one substance selected from the group consisting of polyethylene, polyethylene wax and paraffin wax in a liquid carrier having a high resistivity and a low dielectric constant.

Growing community of inventors

Numazu, Japan

Junichiro Hashimoto