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US4591262A Expired / Lapsed US ⏱️ 0.0 years remaining

Electrostatic copying apparatus

Assignee: Ricoh Co Ltd
•
Filing: 1979-09-17
•
Granted: 1986-05-27
•
Expires: 1999-09-17
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Abstract

Abstract A primary corona charging unit (13) applies a uniform electrostatic charge to a photoconductive drum (12) prior to radiation of the drum (12) with a light image of an original document (26) to form an electrostatic image. The electrostatic image is developed and transferred to a copy sheet (31) by use of a corona transfer charger (14) and separation charger (16). An A.C. corona discharger (17) discharges the drum (12) prior to recharging by the primary charger (13). The primary charger (13) is de-energized prior to the end of a copying operation to prevent charging of non-image areas of the drum (12). The copying operation is terminated by stopping rotation of the drum (12) and simultaneously de-energizing all of the other corona chargers (14), (16), (17). At the beginning of a copying operation, the corona chargers (14), (16), (17) are energized simultaneously with starting rotation of the drum (12). The primary charger (13) is not energized until sufficient time has elapsed for the leading edge of a portion of the drum (12) charged by all of the other chargers (14), (16), (17) to reach the primary charger (13).

Inventors

  • 👤 Seiichi Oseto
  • 👤 Itaru Fujimura
  • 👤 Hitoshi Nakamura

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 08:20
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/02; G03G15/0266; G03G15/0291

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 109 words
An electrostatic copying apparatus including a rotary photoconductive member, primary charging means and secondary charging means operatively disposed adjacent to the photoconductive member, the secondary charging means being disposed downstream of the primary charging means in a direction of movement of the photoconductive member, characterized by comprising: control means for, at a beginning of a copying operation, energizing the secondary charging means and subsequently energizing the primary charging means after a predetermined length of time has elapsed which is greater than a period of time required for a leading edge of a portion of the photoconductive member charged by the secondary charging means to reach the primary charging means.
Claim 2
Dependent Claim 109 words
An electrostatic copying apparatus including a rotary photoconductive member, primary charging means and secondary charging means operatively disposed adjacent to the photoconductive member, the secondary charging means being disposed downstream of the primary charging means in a direction of movement of the photoconductive member, characterized by comprising: control means for, at a beginning of a copying operation, energizing the secondary charging means and subsequently energizing the primary charging means after a predetermined length of time has elapsed which is greater than a period of time required for a leading edge of a portion of the photoconductive member charged by the secondary charging means to reach the primary charging means.
Claim 3
Dependent Claim 30 words
An apparatus as in claim 1, further comprising imaging means disposed between the primary charging means and the secondary charging means for radiating a light image onto the photoconductive member.
Claim 4
Dependent Claim 30 words
An apparatus as in claim 2, in which the secondary charging means comprises at least one of a transfer charging unit, a sheet separation charging unit and a discharging unit.
Claim 5
Dependent Claim 44 words
An apparatus as in claim 2, in which the control means is constructed to energize the primary charging means only for a predetermined period of time sufficient to charge a portion of the photoconductive member on which the imaging means radiates the light image.
Claim 6
Dependent Claim 23 words
An apparatus as in claim 1, in which the primary charging means and the secondary charging means each comprise a corona charging unit.
Claim 7
Dependent Claim 29 words
An apparatus as in claim 1, in which the control means is further constructed to cause the photoconductive member to start rotating simultaneously with energizing the secondary charging means.
Claim 8
Dependent Claim 35 words
An apparatus as in claim 6, in which the control means is further constructed to, at an end of a copying operation, simultaneously de-energize the secondary charging means and stop rotation of the photoconductive member.

References Cited (Backward Citations)

US4017170A Cited
US4017170B1 Cited
DE2609224A1 Cited
US4141648A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1989-05-26 1989-11-25 1990-05-27 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1993-05-26 1993-11-25 1994-05-27 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1997-05-26 1997-11-25 1998-05-27 $7700.00 Window Closed / Lapsed

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