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:
Oct. 20, 1998
Filed:
Jun. 06, 1997
Takayuki Maruta, Tokyo, JP;
Hiroshi Takashima, Yono, JP;
Tomoji Ishikawa, Yokohama, JP;
Kazuyuki Sugihara, Yokohama, JP;
Shinji Kato, Kawasaki, JP;
Katsuhiro Kosuge, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller. The second developing bias generates an electric field where the developer on the developer carrying roller is more reluctant to move toward the photosensitive drum as compared with the first developing bias. The second developing bias may include only a d.c. component.