Abstract: Magnetic toner involves magnetic powder 1 having the particle shape of an octahedron 2 that is a convex polyhedron surrounded by eight triangles as a basis, each of the vertexes and edges of the octahedron being in a curved surface shape, and having a portion 3 that can be taken as a straight line on the outer periphery of its projected image. Therefore, the magnetic toner is superior in both two contradictory properties, that is the property of making it easy for a charging amount to quickly rise as well as improving the charging amount and the property of making it difficult for charge-up to occur, thereby making it possible to form a good image under a wide environment. In an image forming method, an electrostatic latent image is developed into a toner image by a magnetic one-component jumping developing method using the magnetic toner.

Abstract: The toner of the present invention is characterized in that the charges rise up rapidly, the charge quantity is not insufficient nor excessive, the photoreceptor contamination is minimized and the toner is endurable under harsh conditions and against the high stress usage. The magnetic particle contained in the toner is of average particle size 0.01 ?m through 0.50 ?m, is of octahedron shape that is a convex polyhedron surrounded by eight triangles as a basis, each of vertexes and edges of the octahedron being in a curved surface shape and having a portion that can be taken as a straight line on the outer periphery of a projected image of said octahedron. The sphericity of the toner is 0.94 through 0.98. Here, the sphericity is defined by C2/C1, where C1 is a circumferential length of an image projected on a plane and C2 is a circumferential length of an assumed circle area as same as that of the projected image. Further, a number content of the toner of particle size 0.6 ?m through 2.

Abstract: The object is to provide a magnetic toner with which toner scattering, toner spent to carrier, development of scratch streaks by the magnetic brush on the photoreceptor drum can be prevented for a prolonged period and a good image characteristic (in image density and background fogging) can be maintained for a prolonged period, and an image forming method using the magnetic toner. A two-component developer comprising carriers and toner which contains magnetic particle at least in a binder resin thereof, the magnetic particle being of basically polyhedral shaped shape, vertexes and edges of said polyhedral shape being curved surfaces, said shape having peripheral parts taken as straight lines in a projected image thereof, saturation magnetization of said toner in a magnetic field of 79.6 kA/m being 4.0 to 15.

Abstract: A two-component developing agent retained on the periphery surface of a magnetic roller 11 and a development roller 12 are brought in contact with each other, the nonmagnetic toner in the two-component developing agent is electrostatically adhered to the periphery surface of the development roller 12, and the nonmagnetic toner on the development roller 12 is sprayed on the periphery surface of a photosensitive drum 13, thereby causing an image of an electrostatic latent image to appear on the photosensitive drum 13 as a toner image. The two-component developing agent for an image forming device thus configured comprises a nonmagnetic toner comprising color particles, and a magnetic carrier, wherein the magnetic carrier has a resin coating layer on the magnetic particle surface, and the critical surface tension of this resin coating layer is 25 dyn/cm or less.

Abstract: The developer comprises magnetic toners and the magnetic carriers which forms magnetic ears on the surface of the developing roller. The magnetic toner is of an average particle size 0.01 ?m through 0.50 ?m and is of octahedron shape that is a convex polyhedron surrounded by eight triangles as a basis, each of the vertexes edges of the octahedron shape toner being in a curved surface shape and having a portion that can be taken as a straight line on the outer periphery of a projected image of the octahedron shape toner. The magnetic ears are electrically charged by the friction between the magnetic toner and the magnetic carriers and the magnetic ears on the developing roller are carried to the electrostatic latent image on the photoreceptor. The latent image is developed by the magnetic toners in the magnetic ears, in a small gap between the developing roller and the photoreceptor.

Abstract: A developer used for an image forming apparatus including the step of forming a color image by using a single photoreceptor and removing a toner remaining on the photoreceptor after the transfer step with a cleaning blade, which developer is composed of a black toner having a circularity of 0.96 or less and a color toner having a circularity of 0.96 or more, in which at least inorganic particles containing Si compound particles and Ti compound particles are externally added to both of the black toner and the color toner, and the amount of the inorganic particles externally added to the black toner and the color toner satisfies the expressions (1) and (2). {Si(C)+Ti(C)}?1.5×{Si(Bk)+Ti(Bk)}??(1) Ti(C)?1.5×Ti(Bk)??(2) (In the expressions, Si(C), Ti(C), Si(Bk) and Ti(Bk) are as described in the specifications.

Abstract: Disclosed is a toner for developing an electrostatic charge image, which contains at least a binder resin, a release agent, and a charge control agent. The ratio of an average charge amount of toner developed on an electrostatic charge image carrier to an average charge amount of a toner thin layer on a developer carrier before development satisfies following equation (1), and the toner has a mean roundness of 0.935 to 0.985, 1.0?A/B?3.0??(1) where A is an average charge amount of toner after development; and B is an average charge amount of toner before development.

Abstract: A two-component developing agent retained on the periphery surface of a magnetic roller 11 and a development roller 12 are brought in contact with each other, the nonmagnetic toner in the two-component developing agent is electrostatically adhered to the periphery surface of the development roller 12, and the nonmagnetic toner on the development roller 12 is sprayed on the periphery surface of a photosensitive drum 13, thereby causing an image of an electrostatic latent image to appear on the photosensitive drum 13 as a toner image. The two-component developing agent for an image forming device thus configured comprises a nonmagnetic toner comprising color particles, and a magnetic carrier, wherein the magnetic carrier has a resin coating layer on the magnetic particle surface, and the critical surface tension of this resin coating layer is 25 dyn/cm or less.

Abstract: A magnetic single component toner for electrostatic latent image development, which is used in a magnetic single component toner projection development method using an a-Si photosensitive member having a film thickness of no more than 30 ?m, and a cleaning blade as a cleaning means for removing toner from the surface of this photosensitive member, so as to develop an electrostatic latent image formed on the photosensitive member, with a developing agent bearing member, comprises strontium titanate which has been rendered hydrophobic and has a specific surface area of 8.0 to 30 m2/g, and which is added as an external additive at a ratio of 0.3 to 5.0 parts by mass with respect to 100 parts by mass of the toner particle.

Abstract: When a titanium oxide surface-treated with a titanate-based coupling agent is used as an external additive on the surface of toner particles, titanium oxides are likely to be aggregated with each other and aggregated titanium oxide particles are likely to fall off from the surface of the toner. As a result, since toner particles do not support a required amount of titanium oxide particles, poor charging of the toner may occur and fog increases. Therefore, when a toner for electrostatic latent image development comprises color particles containing at least a binder resin and a colorant, and titanium oxide, as an external additive, formed on the surface of the color particles, the titanium oxide being surface-treated with a titanate-based coupling agent containing 30% or less of a solvent soluble component, aggregation of titanium oxides can be reduced and stable charging of the toner can be achieved, and thus the resulting image is stable for a long period.

Abstract: The toner of the present invention is characterized in that the charges rise up rapidly, the charge quantity is not insufficient nor excessive, the photoreceptor contamination is minimized and the toner is endurable under harsh conditions and against the high stress usage. The magnetic particle contained in the toner is of average particle size 0.01 ?m through 0.50 ?m, is of octahedron shape that is a convex polyhedron surrounded by eight triangles as a basis, each of vertexes and edges of the octahedron being in a curved surface shape and having a portion that can be taken as a straight line on the outer periphery of a projected image of said octahedron. The sphericity of the toner is 0.94 through 0.98. Here, the sphericity is defined by C2/C1, where C1 is a circumferential length of an image projected on a plane and C2 is a circumferential length of an assumed circle area as same as that of the projected image. Further, a number content of the toner of particle size 0.6 ?m through 2.

Abstract: The object is to provide a magnetic toner with which toner scattering, toner spent to carrier, development of scratch streaks by the magnetic brush on the photoreceptor drum can be prevented for a prolonged period and a good image characteristic (in image density and background fogging) can be maintained for a prolonged period, and an image forming method using the magnetic toner. A two-component developer comprising carriers and toner which contains magnetic particle at least in a binder resin thereof, the magnetic particle being of basically polyhedral shaped shape, vertexes and edges of said polyhedral shape being curved surfaces, said shape having peripheral parts taken as straight lines in a projected image thereof, saturation magnetization of said toner in a magnetic field of 79.6 kA/m being 4.0 to 15.

Abstract: The two component developer comprises magnetic toners and the magnetic carriers which forms magnetic ears on the surface of the developing roller. The magnetic toner is of an average particle size 0.01 ?m through 0.50 ?m and is of octahedron shape that is a convex polyhedron surrounded by eight triangles as a basis, each of the vertexes and edges of the octahedron shape toner being in a curved surface shape and having a portion that can be taken as a straight line on the outer periphery of a projected image of the octahedron shape toner. The magnetic ears are electrically charged by the friction between the magnetic toner and the magnetic carriers and the magnetic ears on the developing roller are carried to the electrostatic latent image on the photoreceptor. The latent image is developed by the magnetic toners in the magnetic ears, in a small gap between the developing roller and the photoreceptor.

Abstract: Magnetic toner involves magnetic powder 1 having the particle shape of an octahedron2 that is a convex polyhedron surrounded by eight triangles as a basis, each of the vertexes and edges of the octahedron being in a curved surface shape, and having a portion 3 that can be taken as a straight line on the outer periphery of its projected image. Therefore, the magnetic toner is superior in both two contradictory properties, that is, the property of making it easy for a charging amount to quickly rise as well as improving the charging amount and the property of preventing dielectric breakdown of the photosensitive layer of the amorphous silicon photoreceptor from occurring within a short period due to charge-up, thereby making it possible to form a good image under a wide environment. In an image forming method, an electrostatic latent image is developed into a toner image by a magnetic one-component jumping developing method using the magnetic toner.

Abstract: Magnetic toner involves magnetic powder 1 having the particle shape of an octahedron 2 that is a convex polyhedron surrounded by eight triangles as a basis, each of the vertexes and edges of the octahedron being in a curved surface shape, and having a portion 3 that can be taken as a straight line on the outer periphery of its projected image. Therefore, the magnetic toner is superior in both two contradictory properties, that is the property of making it easy for a charging amount to quickly rise as well as improving the charging amount and the property of making it difficult for charge-up to occur, thereby making it possible to form a good image under a wide environment. In an image forming method, an electrostatic latent image is developed into a toner image by a magnetic one-component jumping developing method using the magnetic toner.

Abstract: A developing apparatus has a developer supporting member 41 with a surface roughness RZ in the range from 3.0 to 5.5 &mgr;m and a one-component developer T with a bulk density in the range from 0.35 to 0.55 g/ml, and an image is developed by forming a layer of the developer T on the developer supporting member 41. This makes it possible to form a thin toner layer stably despite changes in ambient conditions, and to prevent low image density and fogging. The absolute value of the amount of electric charge with which the developer T is charged is preferably in the range from 3.0 to 10.0 &mgr;C/g. The developer supporting member 41 is made preferably of stainless steel.

Abstract: A developing apparatus has a developer supporting member 41 with a surface roughness RZ in the range from 3.0 to 5.5 &mgr;m and a one-component developer T with a bulk density in the range from 0.35 to 0.55 g/ml, and an image is developed by forming a layer of the developer T on the developer supporting member 41. This makes it possible to form a thin toner layer stably despite changes in ambient conditions, and to prevent low image density and fogging. The absolute value of the amount of electric charge with which the developer T is charged is preferably in the range from 3.0 to 10.0 &mgr;C/g. The developer supporting member 41 is made preferably of stainless steel.