US4990955A
Expired / Lapsed
US
⏱️ 0.0 years remaining
White level stabilization for tri-level imaging
Assignee: Xerox Corp
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Filing: 1989-04-10
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Granted: 1991-02-05
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Expires: 2009-04-10
Abstract
Abstract Stabilization of the white or background discharge voltage level of tri-level images is accomplished by monitoring photoreceptor white discharge level in the inter-document area of the photoreceptor using an electrostatic voltmeter. The information obtained thereby is utilized to control the output of a raster output scanner so as to maintain the white discharge level at a predetermined level.
Inventors
- 👤 Jerome E. May
- 👤 Delmer G. Parker
- 👤 Howard M. Stark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:08
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/50; G03G15/5033; G03G15/5037; G03G15/01
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
124 words
A method of creating tri-level images on a charge retentive surface, said method including the steps of: uniformly charging said charge retentive surface; exposing said uniformly charged surface to form charged-area images, discharged-area images and white discharge areas; generating signals representative of the white discharge level on said charge retentive surface; utilizing said signals for controlling said exposing step for maintaining said white discharge level at a predetermined level said step of exposing comprising exposing said uniformly charged surface to a three level raster output scanner to form tri-level images spaced apart by an inter-document white discharge level area; and said signal generating step comprising monitoring the interdocument white discharge level voltage level and generating an output signal representing said white discharge level voltage.
Claim 2
Independent Claim
124 words
A method of creating tri-level images on a charge retentive surface, said method including the steps of: uniformly charging said charge retentive surface; exposing said uniformly charged surface to form charged-area images, discharged-area images and white discharge areas; generating signals representative of the white discharge level on said charge retentive surface; utilizing said signals for controlling said exposing step for maintaining said white discharge level at a predetermined level said step of exposing comprising exposing said uniformly charged surface to a three level raster output scanner to form tri-level images spaced apart by an inter-document white discharge level area; and said signal generating step comprising monitoring the interdocument white discharge level voltage level and generating an output signal representing said white discharge level voltage.
Claim 3
Dependent Claim
32 words
The method according to claim 1 wherein said signal output utilizing step comprises utilizing said output signals for controlling said exposing step for maintaining said white discharge level at a predetermined level.
Claim 4
Dependent Claim
40 words
The method according to claim 2 wherein said output signal is utilized such that the white level output of said scanner is not varied while a tri-level image is being formed thereby avoiding white level gradients in the image areas.
Claim 5
Dependent Claim
14 words
The method according to claim 3 wherein said predetermined level is approximately 400 volts.
Claim 6
Dependent Claim
129 words
Apparatus for creating tri-level images on a charge retentive surface, said apparatus comprising: means for uniformly charging said chargere tentive surface; means for exposing said uniformly charged surface to form charged-area images, discharged-area images and white discharge level areas; means for generating signals representative of the white discharge level on said charge retentive surface; means for utilizing said signals for controlling said exposing means for maintaining said white discharge level at a predetermined level said exposing means comprising means for exposing said uniformly charged surface to a three-level raster output scanner to form trilevel images spaced apart by an inter-document white discharge level area; and said signal generating means comprising means for monitoring the inter-document white discharge level voltage and generating output signals representing said white discharge level voltage
Claim 7
Dependent Claim
129 words
Apparatus for creating tri-level images on a charge retentive surface, said apparatus comprising: means for uniformly charging said chargere tentive surface; means for exposing said uniformly charged surface to form charged-area images, discharged-area images and white discharge level areas; means for generating signals representative of the white discharge level on said charge retentive surface; means for utilizing said signals for controlling said exposing means for maintaining said white discharge level at a predetermined level said exposing means comprising means for exposing said uniformly charged surface to a three-level raster output scanner to form trilevel images spaced apart by an inter-document white discharge level area; and said signal generating means comprising means for monitoring the inter-document white discharge level voltage and generating output signals representing said white discharge level voltage
Claim 8
Dependent Claim
39 words
Apparatus according to claim 5 wherein said output signals are utilized such that the white level output of said scanner is not varied while a tri-level image is being formed thereby avoiding white level gradients in the image areas.
Claim 9
Dependent Claim
13 words
Apparatus according to claim 6 wherein said predetermined level is approximately 400 volts.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |