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:
Apr. 27, 1999
Filed:
Mar. 24, 1997
Keitaro Yamashita, Saitama-ken, JP;
Hitachi Metals, Ltd., Tokyo, JP;
Hitachi Metals Kiko, Ltd., Gunma-Ken, JP;
Abstract
A magnet roll including a cylindrical permanent magnet having a surface thereon a plurality of magnetic poles which extend along an axis of the magnet roll and an electroconductive ceramic layer formed at least on a circumferential surface of the cylindrical permanent magnet. The electroconductive ceramic layer may be TiC, WC, TiN, TiCN, CrN, ZrN, HfN, Ti+TiN, and Cr+CrN. The magnet roll is used in a developing method of developing a latent image on a photosensitive drum by a magnetic developer while applying a bias voltage to a developing zone, in which the number of the magnetic poles (N) satisfies the relation: N.gtoreq.(V.sub.1 /V.sub.2).times..pi.D/6, wherein V.sub.1 is a peripheral speed (mm/s) of the photosensitive drum, V.sub.2 is a peripheral speed of the magnet roll and D is an outer diameter (mm) of the magnet roll.