US 2008/0304843 A1 · IMAGE FORMING APPARATUS AND PROCESS CARTRIDGE

Abstract

An image forming apparatus including an image bearing member the moving surface of which travels, a charging device including a charging member located facing the moving surface of the image bearing member, which uniformly charges the moving surface of the image bearing member to form a latent electrostatic image thereon by applying a charging bias in which an AC voltage is overlapped with a DC voltage to the charging member, a developing device to develop the latent electrostatic image with toner to form a toner image on the moving surface of the image bearing member, a transfer device to transfer the toner image on the moving surface of the image bearing member to a recording medium, a fixing device to fix the toner image on the recording medium, an image formation speed switching device to switch from one image formation speed to another image formation speed among multiple image formation speeds by changing a surface traveling speed of the image bearing member according to a particular switching condition, a storage device to store a charging current target of the charging bias applied to the charging member for each of the multiple image formation speeds, an electric current detection device to detect an electric current flown through the charging member and an AC voltage adjustment device to adjust an AC voltage of the charging bias applied to the charging member such that the electric current detected by the electric current detection device approaches the charging current target stored at the storage device which corresponds to the image formation speed when the electric current is detected. With regard to at least two image formation speeds among the multiple image speeds, the charging current target is set for each of the at least two image formation speeds such that each AC voltage adjusted by the AC voltage adjustment device is substantially the same.

Claims17

Dependent claims

An image forming apparatus comprising:

an image bearing member with a moving surface which travels;
a charging device comprising a charging member located facing the moving surface of the image bearing member, the charging device being configured to uniformly charge the moving surface of the image bearing member to form a latent electrostatic image thereon by applying a charging bias in which an AC voltage is overlapped with a DC voltage to the charging member;
a developing device configured to develop the latent electrostatic image with toner to form a toner image on the moving surface of the image bearing member;
a transfer device configured to transfer the toner image on the moving surface of the image bearing member to a recording medium;
a fixing device configured to fix the toner image on the recording medium;
an image formation speed switching device configured to switch from one image formation speed to another image formation speed among multiple image formation speeds by changing a surface traveling speed of the image bearing member according to a particular switching condition;
a storage device configured to store a charging current target of the charging bias applied to the charging member for each of the multiple image formation speeds;
an electric current detection device configured to detect an electric current flown through the charging member;
and
an AC voltage adjustment device configured to adjust an AC voltage of the charging bias applied to the charging member such that the electric current detected by the electric current detection device approaches the charging current target stored at the storage device which corresponds to the image formation speed when the electric current is detected,
wherein with regard to at least two image formation speeds among the multiple image speeds, the charging current target is set for each of the at least two image formation speeds such that each AC voltage adjusted by the AC voltage adjustment device is substantially the same.

8 more elements

A method of forming images comprising:

charging a moving surface of an image bearing member with a charging device comprising a charging member located facing the moving surface of the image bearing member, the charging device being configured to uniformly charge the moving surface of the image bearing member to form a latent electrostatic image thereon by applying a charging bias in which an AC voltage is overlapped with a DC voltage to the charging member;
irradiating the moving surface of the image bearing member to form a latent electrostatic image thereon;
developing the latent electrostatic image with toner to form a toner image on the moving surface of the image bearing member with a developing device;
transferring the toner image on the moving surface of the image bearing member to a recording medium with a transfer device;
fixing the toner image on the recording medium with a fixing device;
switching from one image formation speed to another image formation speed among multiple image formation speeds by changing a surface traveling speed of the image bearing member according to a particular switching condition with an image formation speed switching device;
storing a charging current target of the charging bias applied to the charging member for each of the multiple image formation speeds by a storage device;
detecting an electric current flown through the charging member with an electric current detection device;
and
adjusting an AC voltage of the charging bias applied to the charging member with an AC voltage adjustment device such that the electric current detected by the electric current detection device approaches the charging current target stored at the storage device which corresponds to the image formation speed when the electric current is detected,
wherein with regard to at least two image formation speeds among the multiple image speeds, the charging current target is set for each of the at least two image formation speeds such that each AC voltage adjusted by the AC voltage adjustment device is substantially the same.

8 more elements

Dependencies are inferred from the claim text.

Image forming apparatus and process cartridge

Life of this patent

Image forming apparatus and process cartridge

Life of this patent

Abstract

Claims17