Abstract: A charging roll which is held in contact with an outer circumferential surface of an image bearing medium for charging the surface of the image bearing medium by application of a DC voltage and an AC voltage which is superimposed on the DC voltage, the charging roll comprising: a center shaft; an electrically conductive base layer formed on an outer circumferential surface of the shaft; an outer structure formed on an outer circumferential surface of the conductive base layer; and the charging roll having Asker C hardness of less than 48 degrees as measured upon application of 1 kg load thereto and micro rubber hardness in a range of 65-85 degrees as measured upon application of 33.85 g load thereto.

Abstract: A toner supply roll including a metal shaft and a cylindrical soft polyurethane sponge structure formed on an outer circumferential surface of the metal shaft by foam molding of a polyurethane material in a mold cavity of a mold. The sponge structure having a hardness of 350 g or lower includes a skin layer having generally smooth surface and openings, and a network of cells. The openings are open in the smooth surface and communicate with respective ones of the cells located adjacent to the skin layer, such that the openings are substantially aligned with central portions of the respective ones of the cells in axial and radial directions of the sponge structure. Each opening has a size within a range of 100-800 .mu.m, and a total area of the openings is at least 20% of a total area of the smooth surface of the skin layer. The method of producing the roll is also disclosed.

Abstract: A conductive roll including a conductive shaft, a conductive rubber foam layer formed on an outer circumferential surface of the conductive shaft, and a semi-conductive solid rubber layer formed on an outer circumferential surface of the conductive rubber foam layer. The conductive roll is produced by forming a cylindrical laminar body which gives the conductive rubber foam layer and semi-conductive solid rubber layer, and simultaneously vulcanizing and foaming the laminar body in a mold in which the conductive shaft is placed in position.

Abstract: A conductive roll including a conductive shaft, a conductive rubber foam layer formed on an outer circumferential surface of the conductive shaft, and a semi-conductive solid rubber layer formed on an outer circumferential surface of the conductive rubber foam layer. The conductive roll is produced by forming a cylindrical laminar body which gives the conductive rubber foam layer and semi-conductive solid rubber layer, and simultaneously vulcanizing and foaming the laminar body in a mold in which the conductive shaft is placed in position.

Abstract: An electrically conductive roll is disclosed, which includes: a center shaft; a base layer formed on an outer circumferential surface of the center shaft and including an elastic material as a major component and an ion-conductive material, the base layer having a volume resistivity of 10.sup.6 -10.sup.9 .OMEGA.cm; an electrode layer formed on an outer surface of the base layer and including a synthetic resin material as a major component and an electron-conductive material, the electrode layer having a volume resistivity of not more than 10.sup.3 .OMEGA.cm; a resistance adjusting layer formed on an outer surface of the electrode layer; and a protective layer formed on an outer surface of the resistance adjusting layer.

Abstract: A crowned resilient roll whose diameter is continuously increased from axially opposite ends of the roll toward an axially middle point thereof is disclosed. The resilient roll includes a columnar roll body formed of a resilient material, and a coating layer formed on an outer circumferential surface of the roll body. The thickness of the coating layer is varied in an axial direction of the roll body, such that the coating layer has the largest thickness at an axially middle point of the roll body, and such that the thickness is gradually reduced from the middle point toward axially opposite ends of the roll body. Also disclosed is a method of making such a crowned resilient roll having a coating layer of varying thickness.

Abstract: A crowned resilient roll whose diameter is continuously increased from axially opposite ends of the roll toward an axially middle point thereof is disclosed. The resilient roll includes a columnar roll body formed of a resilient material, and a coating layer formed on an outer circumferential surface of the roll body. The thickness of the coating layer is varied in an axial direction of the roll body, such that the coating layer has the largest thickness at an axially middle point of the roll body, and such that the thickness is gradually reduced from the middle point toward axially opposite ends of the roll body. Also disclosed is a method of making such a crowned resilient roll having a coating layer of varying thickness.