Canon Kabushiki Kaisha

Koshi Suematsu

Eiichi Imai

Masanori Takenouchi

Takeshi Ikeda

Motoo Urawa

Katsuhiko Tanaka

Hiroshi Fukumoto

Kenji Okado

Masaki Uchiyama

Yasuo Mitsuhashi

Koji Goto

Atsuko Yamamoto

A triboelectrically chargeable composition for use in development of electrostatic latent images. The composition comprises a positively chargeable compound and a base material carrying the positively chargeable compound. The positively chargeable compound has an oxidation potential of 750 mV or below, a whiteness W of 0.5 or above and an average particle size of 5.0 microns or smaller. The composition is embodied typically as a positively chargeable toner and also as a charge-imparting material for charging a toner. The positively chargeable toner is especially adapted for development of digital latent images, e.g., as produced by laser beam scanning.

Positively chargeable electrostatic toner containing organic metal

An electrostatic image is developed by disposing an electrostatic image bearing member which holds an electrostatic image on its surface and a developer carrying member which carries an insulating developer on its surface with a certain gap provided therebetween, at a developing section bringing an insulating developer containing a nitrogen-containing compound to a thickness thinner than the gap on the developer carrying member and transferring said developer onto the above electrostatic image bearing member at the developing section. The nitrogen-containing compound has nitrogen in the form of a heterocyclic ring and imparts stable positive chargeability to the developer.

Electrophotographic positively chargeable developer containing silica

A method for developing electrostatic latent images formed on an electrostatic image bearing member, particularly by a thin and uniform layer of toner formed on a toner carrying member. In the method, good images can be stably obtained by controlling the packing density within the range of 0.1 to 0.6 g/cm.sup.3 with respect to the toner layer carried on the toner carrying member at the developing station.

Method for developing electrostatic latent image with non-magnetic toner

A triboelectrically chargeable composition for use in development of electrostatic latent images. The composition contains a substituted guanidine compound having at least one substituent group. The substituted guanidine compound is preferably one represented by the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different groups including hydrogen atom, alkyl, cycloalkyl, alkenyl, aryl, aralkyl, alkaryl, and heterocyclic groups, of which a hydrogen atom may be further replaced by a substituent group, and at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is a group other than hydrogen. The composition is embodied typically as a positively chargeable toner and also as a charge-imparting material for charging a toner.

Toner, charge-imparting material and composition containing substituted

A substantially nonmagnetic toner comprising a colorant and a binder comprising a homopolymer or copolymer having a ratio (Mw/Mn) of a weight-average molecular weight (Mw) of a number average molecular weight (Mn) of less than 5.0 is formed in a thin layer on a toner carrying member. The layer of toner is carried to a developing zone at which an image bearing member is disposed to face the toner carrying member with a clearance larger than the toner layer thickness and an electrostatic image on the image bearing member is developed with the thin layer of toner. The toner binder resin preferably comprises a copolymer of a vinyl monomer and an amonoacrylic monomer.

Process for developing electrostatic images and toner therefor

A method for applying a toner comprising: forming, in a container containing a toner and magnetic particles for application of the toner, a magnetic brush of the magnetic particles; circulating the magnetic particles in the container; and forming a thin layer of the toner electrically charged on the toner carrying member; wherein the magnetic particles have a particle size distribution of 30 wt. % or more in the range of 150 to 200 mesh and 5 wt. % or less of under 250 mesh, and the weight ratio of the toner to the magnetic particles is from 5:95 to 50:50 in the region where the magnetic brush is formed.

Toner application method and developer composition

A thin layer of triboelectrically charged toner for developing an electrostatic latent image is formed by forming a magnetic brush of magnetic particles in a container containing the toner and the magnetic particles, and circulating the magnetic brush in the container on a toner carrying member. In this case, a uniform layer of toner adapted for development is obtained, if the magnetic particles have specific shape characteristics such that, where each magnetic particle is assumed to be circumscribed with a rectangular parallelopiped having edge length of a, b and c satisfying a.gtoreq.b.gtoreq.c with the proviso that all of a, b and c are not the same, the average of b/a is from 0.4 to 1.0 and the average of c/a is from 0.4 to 0.95.

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Kawasaki, Japan

Koshi Suematsu