Electrophotographic apparatus of improved low image density

An electrophotographic apparatus comprising

• a magnetic developer,
• an electrostatic latent image holding member rotating in a specified direction,
• a removing roller which is placed at a position with a specified distance apart from a surface of said electrostatic latent image holding member and which rotates in a direction opposite to the rotation of said electrostatic latent image holding member,
• a developer reservoir for supplying said magnetic developer to the surface of said electrostatic latent image holding member,
• a means for applying an AC voltage to said removing roller to remove the magnetic developer retained on non-image areas of said electrostatic latent image holding member,
• a magnetic field generating means installed inside said electrostatic latent image holding member for producing two magnetic poles having polarity different from each other on the surface of said electrostatic latent image holding member in a vicinity of developing areas where said electrostatic latent image holding member comes closest to said removing roller, and
• a magnetic field generating means installed inside said removing roller for producing two magnetic poles having polarity different from each other on a surface of said removing roller in the vicinity of developing areas where said electrostatic latent image holding member comes closest to said removing roller,
• wherein one of the two magnetic poles installed inside the electrostatic latent image holding member, which is located at the downstream side of the direction of rotation of the electrostatic latent image holding member, and which has a given polarity, comes opposite to one of the two magnetic poles installed inside the removing roller, which also has said given polarity, and which is located at the upstream side of the rotation of the removing roller, at the vicinity of areas where said electrostatic latent image holding member comes closest to said removing roller.

An electrophotographic apparatus comprising a magnetic developer, an electrostatic latent image holding member rotating in a specified direction, a removing roller comprising a means for increasing friction force against said developer, said removing roller placed at a position with a specified distance apart from a surface of said electrostatic latent image holding member and rotating in a direction opposite to the rotation of said electrostatic latent image holding member, a developer reservoir for supplying said magnetic developer to the surface of said electrostatic latent image holding member, a means for applying an AC voltage to said removing roller to remove the developer retained on non-image areas of said electrostatic latent image holding member, and a magnetic field generating means installed inside said electrostatic latent image holding member for producing a magnetic field on the surface of said electrostatic latent image holding member in a vicinity of developing areas where said electrostatic latent image holding member comes closest to said removing roller wherein said removing roller removes said developer retained on said non-image areas of said electrostatic latent image holding member at the vicinity of developing areas where said electrostatic latent image holding member comes closest to said removing roller without slippage because of the friction force caused by said means for increasing friction force.

A method for forming an image by an electrophotographic apparatus comprising:

• (a) forming an electrostatic latent image on a surface of an electrostatic latent image holding member;
• (b) applying a magnetic developer to the surface of the electrostatic latent image holding member, thereby applying the magnetic developer to image and non-image areas of the surface of the electrostatic latent image holding member;
• (c) attaching the magnetic developer to the surface of the electrostatic latent image holding member by a first magnetic field generating means installed inside the electrostatic latent image holding member, said magnetic field generating means producing two magnetic poles, having polarity different from each other, on the surface of the electrostatic latent image holding member;
• (d) passing a removing roller, comprising a second magnetic field generating means installed therein, to remove the magnetic developer from the non-image areas of the electrostatic latent image holding member, said second magnetic field generating means produces a magnetic pole, having a given polarity, on a surface of the removing roller;
• and
• (e) transferring onto paper the magnetic developer from the image areas, wherein one of the magnetic poles installed inside the electrostatic latent image holding member, which is located at the downstream side of the direction of rotation of the electrostatic latent image holding member, and which has a given polarity, comes opposite to a magnetic pole installed inside the removing roller, which has said given polarity, at a vicinity of area where said electrostatic latent image holding member comes closest to said removing roller.