Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.