Patent US4306804A successfully refreshed from Google Patents.
US4306804A
Expired / Lapsed
US
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Exposure control and other component control for electrostatic copying machine
Assignee: Ricoh Co Ltd
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Filing: 1979-08-06
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Granted: 1981-12-22
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Expires: 1999-08-06
Abstract
Abstract An exposure unit radiates a light image of an original document onto a charged photoconductive member to form an electrostatic image through localized photoconduction. A developing unit applies a powdered developing substance comprising carrier particles and toner particles to the photoconductive member to develop the electrostatic image and produce a toner image which is transferred and fixed to a copy sheet to produce a permanent reproduction of the original document. Prior to exposure with the light image a reference electrostatic image is formed on the photoconductive member and the electrostatic potential thereof is measured. The intensity of the light image of the original document and/or a developing bias voltage are regulated in accordance with the sensed electrostatic potential. The reference image may be of a reference surface having a predetermined optical density or a portion of the original document produced by reverse optical scanning.
Inventors
- 👤 Koji Sakamoto
- 👤 Seiichi Miyakawa
- 👤 Susumu Tatsumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:14
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/50; G03G15/5033; G03G15/5037; G03G15/06; G03G15/08; G03G15/0822; G03G15/0848; G03G15/0849; G03G15/0853; Y; Y10; Y10S; Y10S222/00; Y10S222/01
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
215 words
In an electrostatic copying machine including a photoconductive member, a charging unit for applying a uniform electrostatic charge to the photoconductive member and an exposure means for radiating a light image of an original document onto the photoconductive member to form an electrostatic image thereon through localized photoconduction, the improvement comprising: first control means for controlling the exposure unit to radiate a reference light image onto the photoconductive member to form a reference electrostatic image thereon; sensor means for sensing an electrostatic potential of the reference electrostatic image; and second control means for controlling the exposure unit in such a manner as to regulate an intensity of the light image of the original document in accordance with the sensed electro-potential of the reference electrostatic image; said exposure means comprising a scan member movable in a scan and a return direction for radiating the light image of the original document onto the photoconductive member, the first control means controlling said exposure means to move the scan member by a predetermined distance in the return direction for radiating the reference light image onto the photoconductive member, the reference light image being constituted by a light image of a portion of the original document corresponding to the predetermined distance the scan member is moved in the return direction.
Claim 2
Dependent Claim
215 words
In an electrostatic copying machine including a photoconductive member, a charging unit for applying a uniform electrostatic charge to the photoconductive member and an exposure means for radiating a light image of an original document onto the photoconductive member to form an electrostatic image thereon through localized photoconduction, the improvement comprising: first control means for controlling the exposure unit to radiate a reference light image onto the photoconductive member to form a reference electrostatic image thereon; sensor means for sensing an electrostatic potential of the reference electrostatic image; and second control means for controlling the exposure unit in such a manner as to regulate an intensity of the light image of the original document in accordance with the sensed electro-potential of the reference electrostatic image; said exposure means comprising a scan member movable in a scan and a return direction for radiating the light image of the original document onto the photoconductive member, the first control means controlling said exposure means to move the scan member by a predetermined distance in the return direction for radiating the reference light image onto the photoconductive member, the reference light image being constituted by a light image of a portion of the original document corresponding to the predetermined distance the scan member is moved in the return direction.
Claim 3
Dependent Claim
56 words
A copying machine as in claim 1, further comprising developing means and bias source means for applying a bias voltage to the developing means, the second control means further controlling the bias source means in such a manner as to regulate the bias voltage in accordance with the sensed electrostatic potential of the reference electrostatic image.
Claim 4
Dependent Claim
26 words
A copying machine as in claim 1, in which said exposure means moves the scan member faster in the return direction than in the scan direction.
Claim 5
Dependent Claim
34 words
A copying machine as in claim 1, in which said exposure means comprises a diaphragm means controlled by said second control means to regulate the intensity of the light image of the original document.
References Cited (Backward Citations)
US3788739A
Cited
US4050806A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-21 | 1985-06-22 | 1985-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-21 | 1989-06-22 | 1989-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-21 | 1993-06-22 | 1993-12-22 | $7700.00 | Window Closed / Lapsed |