| US 7,383,003 B2 | ||
| Developing apparatus for preventing ghost images and uneven image density | ||
| Naoto Kichijima, Mishima (Japan); Koichi Okuda, Tokyo (Japan); Yasushi Shimizu, Shizuoka-ken (Japan); Kenya Ogawa, Susono (Japan); Shuji Moriya, Shizuoka-ken (Japan); and Kazunari Hagiwara, Numazu (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Apr. 12, 2006, as Appl. No. 11/402,054. | ||
| Claims priority of application No. 2005-119983 (JP), filed on Apr. 18, 2005. | ||
| Prior Publication US 2006/0233573 A1, Oct. 19, 2006 | ||
| Int. Cl. G03G 15/09 (2006.01) | ||
| U.S. Cl. 399—270 [399/55; 399/150; 399/267] | 12 Claims |
| 1. 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 an 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 at the abutting position 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 an 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.
|