Developing device for an image forming apparatus
US5489747A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 1995 |
| Grant date | Feb 6, 1996 |
| Priority date | — |
| Expiry date | Apr 28, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G2215/0861
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A developing device for an image forming apparatus and having a relatively hard first developing roller formed with fine N-S magnetic poles on the periphery thereof, and a relatively soft second developing roller for conveying toner electrostatically transferred thereto from the first roller toward a photoconductive drum. The toner is charged by friction while being passed through between the first roller and a blade, and then magnetically deposited on the first roller. At a position where the first and second rollers contact each other, only the adequately charged toner is electrostatically transferred from the first roller to the second roller. The second roller conveys the toner toward the drum. As a result, the toner is brought to a developing position in an amount corresponding to a saturation or maximum image density. The second roller is made up of a metallic conductive core, a semiconductive foam layer, and an insulative surface layer implemented by resin. The real resistance between the core and the surface is selected to be higher than 10.sup.3 .OMEGA. but lower than 10.sup.13 .OMEGA.. The ratio of the real resistance associated with the maximum temperature change to the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.