Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 ?g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.

Abstract: A charging device includes a charging member disposed opposite to a surface of an image carrier. The image carrier is charged by applying a voltage to the charging member, and the charging member includes a substrate and a resistor layer thereon. The resistor layer is disposed with two spacers contacting with the image carrier, so that a gap is created between the image carrier and the resistor layer between the two spacers, wherein width variation of the gap with time is prevented. The end portions of the resistor layer of the charging member protrude above the resistor layer between them, and the spacers are constituted by protrudent fractions of the end portions of the resistor layer.

Abstract: A charging device includes a charging member disposed opposite to a surface of an image carrier. The image carrier is charged by applying a voltage to the charging member, and the charging member includes a substrate and a resistor layer thereon. The resistor layer is disposed with two spacers contacting with the image carrier, so that a gap is created between the image carrier and the resistor layer between the two spacers, wherein width variation of the gap with time is prevented. The end portions of the resistor layer of the charging member protrude above the resistor layer between them, and the spacers are constituted by protrudent fractions of the end portions of the resistor layer.

Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 ?g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.

Abstract: An intermediate image transfer type, tandem color image forming apparatus of the present invention includes four photoconductive drums assigned to black, yellow, magenta and cyan, respectively. In a black mode, the drums assigned to the colors other than black are released from an intermediate image transfer belt. As soon as the trailing edge of a black toner image is transferred to the intermediate image transfer belt, the above drums are again brought into contact with the belt. The drums and intermediate image transfer belt therefore wear little despite contact thereof and deteriorate little despite pressure acting therebetween.

Abstract: A charging device is described, including a charging member 40BK disposed opposite to a surface of an image carrier 60BK. The image carrier 60BK is charged by applying a voltage to the charging member 40BK, and the charging member 40BK comprises a substrate 101BK and a resistor layer 104BK thereon. The resistor layer 104BK is disposed with two spacers 105BK contacting with the image carrier 60BK, so that a gap is created between the image carrier 60BK and the resistor layer 104BK between the two spacers 105BK, wherein width variation of the gap with time is prevented. The end portions of the resistor layer 104BK of the charging member 60BK protrude above the resistor layer 104BK between them, and the spacers 105BK are constituted by protrudent fractions of the end portions of the resistor layer 104BK.

Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 &mgr;g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.

Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 &mgr;g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.

Abstract: An electrophotographic photoreceptor including an electroconductive substrate and a photoreceptive layer, which is formed overlying the substrate, wherein the photoreceptive layer includes a charge carrier generation layer including a charge carrier generation material and a charge carrier transport layer including a charge carrier transport material, and wherein when an electric field of from 2.5×105 V/cm to 5.5×105 V/cm is applied to the charge carrier transport layer, the relationship, tCTL/&mgr;CTL≦1.5×103 V·s/m, is satisfied, wherein tCTL represents a thickness of the charge carrier transport layer and &mgr;CTL represents a charge mobility of the charge carrier transport layer.

Abstract: An intermediate image transfer type, tandem color image forming apparatus of the present invention includes four photoconductive drums assigned to black, yellow, magenta and cyan, respectively. In a black mode, the drums assigned to the colors other than black are released from an intermediate image transfer belt. As soon as the trailing edge of a black toner image is transferred to the intermediate image transfer belt, the above drums are again brought into contact with the belt. The drums and intermediate image transfer belt therefore wear little despite contact thereof and deteriorate little despite pressure acting therebetween.

Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 &mgr;g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.