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:
Mar. 26, 1996
Filed:
Jun. 17, 1994
Naoki Iwata, Tokyo, JP;
Takeshi Saito, Tokyo, JP;
Hidetoshi Yano, Yokohama, JP;
Hiromitsu Takagaki, Yokohama, JP;
Kazuhiro Nishido, Tokyo, JP;
Ichiro Komuro, Yokohama, JP;
Shigeki Sawa, Yokohama, JP;
Nobuhiro Shima, Gotenba, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
In a developing device for an image forming apparatus, a developing roller has dielectric portions and conductive portions distributed regularly or irregularly over the surface thereof. The surfaces of the dielectric portions are smaller in height than the surfaces of the conductive portions. The difference in height is greater than one-half of the volumetric mean particle size of a toner. A charge opposite in polarity to a charge to be deposited on the toner is deposited on the dielectric portions. The dielectric portions, or recesses, each has a width more than three times as great as the volumetric mean particle size of the toner and a depth less than five times the volumetric particle size. The dielectric portions may be greater in height than the conductive portions and may be implemented as spiral grooves inclined more than 30 degrees relative to the axis of rotation of the developing roller. The developing roller may be moved at a higher linear velocity than a photoconductive drum.