Patent ID: 8126379
Filing Date: 2012-02-28
Classification: G03G

Abstract:
1. A developing device comprising a fixedly disposed magnet body, and a development sleeve which is rotatably fitted onto the magnet body, the developing device forming and retaining developer brushes comprising a developer containing a toner and magnetic carrier particles on a surface of the development sleeve by a magnetic force of the magnet body, transferring the developer brushes to a development region in which an electrostatic latent image formed on a surface of an electrostatic latent image carrier which is rotationally driven is developed, and bringing the developer brushes into contact with the surface of the electrostatic latent image carrier to develop the electrostatic latent image, wherein the magnet body has a group of annularly arranged magnetic poles comprising a development pole which is a single magnetic pole facing the development region; an angular position which indicates a peak value of a magnetic flux density in a normal direction with respect to the surface of the development sleeve produced by the development pole in the magnet body is shifted downstream from an angular position of a center of the development pole in the magnet body in the development region in a direction of movement of the surface of the electrostatic latent image carrier opposing the development sleeve; angular positions which indicate a magnetic flux density of a predetermined proportion of the peak value of the magnetic flux density in the magnet body are positions which are spaced at equal angular intervals upstream and downstream in the direction of movement of the surface of the electrostatic latent image carrier; and the relationship between an angle X from the angular position in the magnet body which indicates the peak value of the magnetic flux density to a position which is downstream of the angular position indicating the peak value and in which the magnetic flux density in the normal direction becomes 0 in the direction of movement of the surface of the electrostatic latent image carrier and an angle Y from the angular position indicating the peak value to a position which is upstream of the angular position indicating the peak value and in which the magnetic flux density in the normal direction becomes 0 is Y>X.