Charging device and image forming apparatus
US5305177A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1991 |
| Grant date | Apr 19, 1994 |
| Priority date | — |
| Expiry date | Nov 1, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/0283
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A charging device includes a charging member contactable to a member to be charged. A bias source includes an AC source and a DC source and is effective to apply a bias voltage to the charging member. The bias voltage is provided by a superposing a constant current controlled AC voltage and a constant voltage controlled DC voltage. When a DC voltage is applied between the charging member and the member to be charged, the following equation is satisfied. PA1 .vertline.(applied voltage V)-(charge voltage V.sub.D of the member to be charged).vertline.=.vertline.(charge starting voltage V.sub.TH).vertline.. The charge starting voltage is a DC voltage at a level which the member to be charged starts charging when only a DC voltage is applied between the member to be charged and the charging member. When the above relationship is used in the AC voltage application, the charge voltage V.sub.D oscillates in the charge region with a center of DC voltage V.sub.DC. Since the peak-to-peak voltage of the oscillating voltage required for uniform charging changes with ambient conditions, it is necessary to compensate for this change. The electric current supplied to the charging member by the osc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.