The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 12, 1996
Filed:
Jul. 20, 1995
Takao Kumasaka, Takahagi, JP;
Yasuo Takuma, Hitachi, JP;
Tatsuo Igawa, Kitaibaraki, JP;
Tomio Sugaya, Hitachinaka, JP;
Yasuo Kikuchi, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Koki Co., Ltd., Tokyo, JP;
Abstract
A developing apparatus in which a stationary multipole permanent magnet is placed in a sleeve and in which development is performed by bringing a developer, which contains at least carrier and toner particles and is held on the periphery of a sleeve by use of the magnetic force of the multipole permanent magnet, into contact with a photo-conductive body owing to the rotation of the sleeve. For securing image density and for preventing the deposition of carrier onto the photo-conductive body, two magnetic pieces, each of which is arranged lengthwise in the direction of the axis thereof and which have the same polarity, are placed in a region in the multipole permanent magnet which faces the photo-conductive body in such a manner as to adjoin in the circumferential direction of said permanent magnet. This results in generation of the distribution of a magnetic field which has two peaks of magnetic force. The position at which the second one of the two peaks of the magnetic force is formed, downstream in the direction of rotation of the sleeve, is set at the nearest point between the photo-conductive body and the sleeve. Thereby, even when development is performed by bringing the developer into light contact with the photo-conductive body, the image density can be secured. Further, the carrier can be prevented from depositing on the photo-conductive body.