Electrophotography – Image formation – Charging
Reexamination Certificate
2008-03-04
2008-03-04
Deb, Anjan (Department: 2858)
Electrophotography
Image formation
Charging
C399S168000, C399S050000, C361S221000
Reexamination Certificate
active
11028611
ABSTRACT:
A charging unit is disclosed capable of reducing undue variation and fluctuation margin of a charging gap, and controlling accurately the proper gap durably over the change of environmental conditions, which is suitably incorporated into an image forming apparatus. The charging unit is configured to charge an image bearing member in a non-contact arrangement, including a charging roller provided with a core shaft, a charging member formed of electroconductive resin integrally disposed on the periphery of the core shaft, and gap holding members formed of insulating resin each disposed at respective ends of the charging member outside an image forming region. The control of the charging gap is feasible by either forming the gap with a charging member having such a materials condition as to satisfy the relation, |G30−G10|×5<G20, where G10, G20and G30are the gap averages at 10°, 20° and 30° C., respectively; or providing the charging roller with gears mounted on respective ends to be engaged with further gears mounted on flanges of the image bearing member to be driven along the rotation, and forming these gears such that the least common multiple of numbers, Nc and Np, is Nc×Np, where Nc and Np are the numbers of gear teeth for the charging roller and image bearing member, respectively.
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Deb Anjan
Zhu John
LandOfFree
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