Charge member, charge apparatus, process cartridge, and image forming apparatus

A process cartridge used in an image forming apparatus, wherein the following are unified and assembled into a single cartridge:

• a charge member which is arranged electrically without making contact with a member to be charged, and which charges the member to be charged by applying AC voltage superimposed on DC voltage, and which is formed of a rotatable roller, is arranged electrically without making contact with the member to be charged having circumferential fluctuations of 4 to 80 μm within an image formation area, has a plurality of stage differences with a height difference of 2 to 30 μm on a surface of the roller, and in which the stage differences in the area opposing the member to be charged are five to thirty in relation to a distance of 0.5 mm in the circumferential direction of the roller;
• a charge apparatus that comprises a power source which applies voltage to the charge member, and which charges the member to be charged by applying AC voltage superimposed on DC voltage to the charge member;
• and
• an image support that is the member to be charged.

An image forming apparatus comprising an image forming unit that has an image support that is a member to be charged, charge means that charges the image support, and means to form an image on the image support, wherein

• the charge means comprises:
• a charge member which is arranged electrically without making contact with a member to be charged, and which charges the member to be charged by applying AC voltage superimposed on DC voltage, and which is formed of a rotatable roller, is arranged electrically without making contact with the member to be charged having circumferential fluctuations of 4 to 8 μm within an image formation area, has a plurality of stage differences with a height difference of 2 to 30 μm on a surface of the roller, and in which the stage differences in the area opposing the member to be charged are five to thirty in relation to a distance of 0.5 mm in the circumferential direction of the roller;
• and
• a charge apparatus which comprises a power source that applies voltage to the charge member, and which charges the member to be charged by applying AC voltage superimposed on DC voltage to the charge member.

An image forming apparatus comprising an image forming unit that has an image support that is a member to be charged, a charge member that charges the image support, and means to form an image on the image support, wherein

• the image forming unit comprises a process cartridge in which the following are unified and assembled into a single cartridge:
• a charge member which is arranged electrically without making contact with a member to be charged, and which charges the member to be charged by applying AC voltage superimposed on DC voltage, and which is formed of a rotatable roller, is arranged electrically without making contact with the member to be charged having circumferential fluctuations of 4 to 80 μm within the image formation area, has a plurality of stage differences with a height difference of 2 to 30 μm on a surface of the roller, and in which the stage differences in the area opposing the member to be charged are five to thirty in relation to a distance of 0.5 mm in the circumferential direction of the roller;
• a charge apparatus which comprises a power source that applies voltage to the charge member, and which charges the member to be charged by applying AC voltage superimposed on DC voltage to the charge member;
• and
• an image support which is the member to be charged.

A process cartridge that can be mounted in an image forming apparatus, wherein

• the image forming apparatus conducts a charging process by applying AC voltage superimposed on DC voltage to an image support and a charge roller arranged electrically without making contact with the image support,
• circumferential fluctuations in the image forming area of the image support are 4 to 80 μm,
• the charge roller has a plurality of continuous stage differences on the surface thereof that have height differences of 2 to 30 μm and lengths of 400 μm or more, and
• when plotting the stage differences respectively by extracting to an XY plane taking the longitudinal axis of the roller as the X axis and conducting collinear approximation by the least squares method, the correlation coefficient is 0.9 or less, and the slope is −0.5 to 0.5.