US 2006/0233573 A1Published application

Developing apparatus

AssigneeCanon Kabushiki Kaisha

InventorsNaoto Kichijima, Koichi Okuda, Yasushi Shimizu, Kenya Ogawa, Shuji Moriya, Kazunari Hagiwara

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Abstract

A developing apparatus having: a rotatable developing roller for developing an electrostatic image with a mono-component magnetic developer at a developing position; a non-rotary magnet roll inside the roller; a blade for regulating the amount of the developer at a developer regulating position; and an abutting member abutting against the roller downstream of the developing position and upstream of the developer regulating position, wherein the following expressions are satisfied: |Vs|>|Vdev|, |Br|/|B|≦0.5, and L/(BH×R)≧0.1, where |Vdev|: a DC component Vdev of a voltage applied to the roller, |Vs|: a DC component Vs of a voltage applied to the member, B(G): the magnetic flux density formed on the surface of the roller at the abutting position by the magnet roll, Br(G): the component of the magnetic flux density B(G) perpendicular to the surface of the roller, and L(mm): the abutting width between the roller and the member, BH(rad): the half value width of the component Bθ(G) horizontal to the surface of the roller, and R(mm): the radius of the roller.

A developing apparatus comprising:

a rotatable developer carrying member carrying a mono-component magnetic developer to develop an electrostatic image formed on an image bearing member with the mono-component magnetic developer at a developing position, said developer carrying member being provided with an elastic layer on a surface of said developer carrying member, said developer carrying member being urged against said image bearing member;
non-rotary magnetic field generating means provided inside said developer carrying member for magnetically attracting the developer to said developer carrying member;
a developer amount regulating member for contacting with said developer carrying member to regulate an amount of the developer carried on said developer carrying member at a developer regulating position;
and
an abutting member abutting against said developer carrying member downstream of said developing position and upstream of said developer regulating position with respect to a rotation direction of said developer carrying member,
wherein the developer is supplied to said developer carrying member downstream of the abutting position of said abutting member against said developer carrying member and upstream of said developer regulating position with respect to the rotation direction of said developer carrying member,
and when a magnitude of a DC component Vdev of a voltage applied to said developer carrying member is defined as |Vdev|, and a magnitude of a DC component Vs of a voltage applied to said abutting member is defined as |Vs|, and a magnitude of magnetic flux density formed on the surface of said developer carrying member by said magnetic field generating means is defined as B(G), and a component of the magnetic flux density B(G) in a direction perpendicular to the surface of said developer carrying member is defined as Br(G), and a abutting width between said developer carrying member and said abutting member is defined as L(mm), and a half value of width of a component Bθ(G) of the magnetic flux density B(G) in a direction horizontal to the surface of said developer carrying member is defined as BH(rad), and a radius of said developer carrying member is defined as R(mm), the following expressions are satisfied:
|Vs|>|Vdev|,
|Br|/|B|≦0.5, and
L/(BH×R)≧0.1.

7 more elements

Abstract

Claims12