Abstract: A rotating part for an image forming apparatus includes a drive member for transmitting power; and a driven member that is rotated by the drive member. The drive member has a male part formed in a direction of a rotation axis, and the driven member has a female part that is formed in the direction of the rotation axis and into which the male part is inserted. The male part is a hexagonal male part whose cross section perpendicular to the rotation axis assumes a hexagonal shape. The female part is a twisted triangular female part that assumes a triangular cross sectional profile in a direction perpendicular to the rotation axis, and a triangle which forms a cross section of a base and a cross section of a top is twisted at a predetermined angle with respect to the rotation axis.

Abstract: The invention provides an electrophotographic photoreceptor for use in an image-forming apparatus comprising a charging unit which charges an electrophotographic photoreceptor, an exposure unit which exposes the charged electrophotographic photoreceptor to light to form an electrostatic latent image on the electrophotographic photoreceptor, and a developing unit which develops the electrostatic latent image, wherein the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer and the photosensitive layer contains a compound represented by the following formula (1).

Abstract: An electrophotographic photoreceptor is provided which comprises a conductive substrate and a photosensitive layer formed thereover, wherein the photosensitive layer contains at least a polyarylate resin having a repeating structure represented by the following formula [1] and a compound represented by the following formula [6]. This photoreceptor has excellent abrasion resistance under practical load, has high mechanical strength, and further has highly excellent electrical properties.

Abstract: The invention provides an electrophotographic photoreceptor for use in an image-forming apparatus comprising a charging unit which charges an electrophotographic photoreceptor, an exposure unit which exposes the charged electrophotographic photoreceptor to light to form an electrostatic latent image on the electrophotographic photoreceptor, and a developing unit which develops the electrostatic latent image, wherein the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer and the photosensitive layer contains a compound represented by the following formula (1).

Abstract: The present invention relates to an electrophotographic photoreceptor having an electroconductive substrate, and a charge transport layer and a charge generation layer formed on the substrate, characterized in that the charge transport layer contains a charge transport material represented by formula (1) and a binder resin, and the mass ratio of the charge transport material to the binder resin is from 5/100 to 45/100: wherein Ar1 is an arylene group which may have a substituent; each of Ar2, Ar3, Ar4 and Ar5 is an aryl group which may have a substituent; and n is an integer of from 3 to 6.

Abstract: An electrophotographic photoreceptor having high sensitivity and hardly affected by the transfer in an electrophotographic process is provided. The electrophotographic photoreceptor includes an undercoat layer containing metal oxide particles and a binder resin and a photosensitive layer disposed on the undercoat layer, wherein the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid of the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3, and the photosensitive layer contains a binder resin having an ester bond.

Abstract: Provided are a coating liquid for forming an undercoat layer exhibiting high stability, a process for forming the coating liquid, a high-performance electrophotographic photoreceptor that is capable of forming a high-quality image under various use environments and exhibiting reduced image defects such as black spots and color spots, and an image-forming apparatus and electrophotographic cartridge including the electrophotographic photoreceptor. In the coating liquid for forming an undercoat layer of an electrophotographic photoreceptor containing metal oxide particles and a binder resin, the metal oxide particles have a number average particle diameter of 0.10 ?m or less and a 10% cumulative particle diameter of 0.060 ?m or less which are measured by a dynamic light-scattering method in the coating liquid for forming an undercoat layer.

Abstract: An electrophotographic photoreceptor having high sensitivity and low residual potential is provided. The electrophotographic photoreceptor includes an undercoat layer containing metal oxide particles and a binder resin on an electroconductive substrate, and a photosensitive layer disposed on the undercoat layer, wherein the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid of the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3; and the photosensitive layer contains crystalline phthalocyanine showing at least one distinct main diffraction peak at a Bragg angle (2?±0.2°) of 27.0° to 29.0° in an X-ray diffraction spectrum.

Abstract: To provide an electrophotographic photoreceptor having a high sensitivity, a good balance of various electric properties such as chargeability and residual potential, a good stability of the coating solution, and an excellent light resistance. An electrophotographic photoreceptor comprising an electroconductive support having thereon a photosensitive layer, wherein the photosensitive layer contains a compound represented by the following formula (1): (wherein R1 represents a group having a chiral center, R2 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent, R3 and R4 each independently represents an alkylene group which may have a substituent, or an arylene group which may have a substituent, and R5, R6, R7 and R8 each independently represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, and at least one member of R5 to R8 is an aryl group having a substituent).

Abstract: Provided is an excellent phthalocyanine crystal having high sensitivity and little fluctuation in sensitivity for a humidity change in a use environment and applicable to the martial for solar battery, electronic paper, electrophotographic photoreceptor, etc. Namely, phthalocyanine crystal obtained by bringing a phthalocyanine crystal precursor into contact with an aromatic aldehyde compound to convert the crystal form. Also, provided is an electrophotographic photoreceptor that not only exhibits high sensitivity but also has little fluctuation in sensitivity for a humidity change in a use environment. Further, provided is an electrophotographic photoreceptor cartridge and an image-forming device, both of which can produce a stable quality images for a humidity change in a use environment by using the electrophotographic photoreceptor.

Abstract: An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies the following formula (1): Dns?0.233 EXP(17.3/Dv50)??(1).

Abstract: An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies the following formula (1): Dns?0.233 EXP(17.3/Dv50)??(1).

Abstract: An image forming apparatus containing an electrophotographic photoreceptor and a toner for developing an electrostatic charge image, where the electrophotographic photoreceptor has an undercoat layer containing metal oxide particles; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies the following formula (1): Dns?0.233EXP(17.3/Dv50)??(1) where Dv50 is the volume median diameter (?m) of the toner, and Dns is the percentage in number of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m.

Abstract: An image forming apparatus containing an electrophotographic photoreceptor and a toner for developing an electrostatic charge image, where the electrophotographic photoreceptor has an electroconductive substrate with a surface roughness Ra of from 0.01 ?m to 0.3 ?m; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies formula (1): Dns?0.233EXP(17.3/Dv50)??(1) where Dv50 is the volume median diameter (?m) of the toner, and Dns is the percentage in number of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m.

Abstract: To provide an image forming apparatus which is able to improve image quality while suppressing soiling of image white parts, scattering in the apparatus, streaks, fading, etc. due to non-uniformity in the particle size distribution of a toner or mismatching between a toner and a photoreceptor, and which has good cleaning properties, and even when a high speed printing machine is used, is able to reduce a problem of soiling, etc. in long-term use and provide excellent image stability.

Abstract: An object of the invention is to provide a toner which is effective in improving image quality while inhibiting white-background fouling, residual-image phenomenon (ghost), blurring (suitability for solid printing), and the like that occur depending on the proportion of a fine powder having a particle diameter not larger than a specific value, and which has satisfactory removability in cleaning, mitigates problems concerning fouling, etc. in long-term use even on a high-speed printer, and attains excellent image stability. Another object is to provide an image-forming apparatus and a toner cartridge each employing the toner. The invention provides a toner for electrostatic-image development satisfying all of the following (1) to (4) or a toner for electrostatic-image development which is a toner containing a charge control agent and satisfying all of the following (5) to (7). The invention further provides an image-forming apparatus and a toner cartridge each employing the toner.

Abstract: To provide an electrophotographic photoreceptor having a high sensitivity, a good balance of various electric properties such as chargeability and residual potential, a good stability of the coating solution, and an excellent light resistance. An electrophotographic photoreceptor comprising an electroconductive support having thereon a photosensitive layer, wherein the photosensitive layer contains a compound represented by the following formula (1): (wherein R1 represents a group having a chiral center, R2 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent, R3 and R4 each independently represents an alkylene group which may have a substituent, or an arylene group which may have a substituent, and R5, R6, R7 and R8 each independently represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, and at least one member of R5 to R8 is an aryl group having a substituent).

Abstract: Subjects for the invention are: to provide an electrophotographic photoreceptor which has excellent electrical characteristics and which, even when repeatedly used over long, can stably form high-quality satisfactory images having high resolution; and to provide an electrophotographic photoreceptor cartridge and an image-forming apparatus each employing the electrophotographic photoreceptor. The invention provides an electrophotographic photoreceptor for use in an image-forming apparatus comprising a charging unit which charges an electrophotographic photoreceptor, an exposure unit which exposes the charged electrophotographic photoreceptor to light to form an electrostatic latent image on the electrophotographic photoreceptor, and a developing unit which develops the electrostatic latent image, wherein the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer and the photosensitive layer contains a compound represented by the following formula (1).

Abstract: An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies the following formula (1): Dns?0.233 EXP(17.

Abstract: An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.0 ?m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 ?m to 3.56 ?m satisfies the following formula (1): Dns?0.233 EXP(17.