Patent US3921571A successfully refreshed from Google Patents.
US3921571A
Expired / Lapsed
US
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Multiple development method and apparatus for electrophotographic copiers
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1974-06-24
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Granted: 1975-11-25
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Expires: 1994-06-24
Abstract
Abstract Electrophotographic copying apparatus having a multiple development capability for more completely developing and, hence, improving the quality of images which contain extended solid areas. This multiple development capability is attained by designing the development station in such a manner that the latent electrostatic image to be developed and the developer mixture will move through the development station at a substantially identical velocity as distinguished from conventional systems in which the developer passes through the development station much faster than the image. By matching the velocities of the image and the developer, degradation of the developed, or partially developed, image by the rubbing or sweeping of the carrier beads across the image will be substantially eliminated, and, accordingly, multiple development becomes possible. The substantial matching of velocities is preferably accomplished by significantly reducing the width of the gap between the latent image bearing medium and the development plate through which the developer falls. This increases the density of developer in the gap and the degree of developer agitation and, hence, causes it to fall much slower while still ensuring an adequate supply for effective development of all areas of the image. With a system designed in this way, copies having a quality equal or superior to those obtainable with conventional systems can be achieved with a single development step and at speeds comparable to those available in todays high speed machines. When, however, the image to be developed contains large extended solid areas, any needed number of additional development cycles can be selectively carried out to better develop such images and, hence, provide superior quality copies.
Inventors
- 👤 Robert A Moore
- 👤 Daniel J Sullivan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:01
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/0801
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
121 words
In an electrophotographic copying apparatus including: a first support medium carrying a latent electrostatic image to be developed thereon; a second support medium for receiving the developed image from said first support medium; transfer means for transferring said developed image from said first support medium to said second support medium; and, developing means for developing said latent electrostatic image on said first support medium prior to the transfer thereof to said second support medium by said transfer means, the improvement comprising: wherein said developing means includes control means for selectively controlling the number of times that said latent electrostatic image is developed prior to the transfer thereof from said first support medium to said second support medium by said transfer means.
Claim 2
Dependent Claim
121 words
In an electrophotographic copying apparatus including: a first support medium carrying a latent electrostatic image to be developed thereon; a second support medium for receiving the developed image from said first support medium; transfer means for transferring said developed image from said first support medium to said second support medium; and, developing means for developing said latent electrostatic image on said first support medium prior to the transfer thereof to said second support medium by said transfer means, the improvement comprising: wherein said developing means includes control means for selectively controlling the number of times that said latent electrostatic image is developed prior to the transfer thereof from said first support medium to said second support medium by said transfer means.
Claim 3
Dependent Claim
55 words
Apparatus as recited in claim 1 wherein said control means further includes selection means for selecting the number of times that said latent electrostatic image is to be developed prior to the transfer thereof from said first support medium to said second support medium, said number of times being from one to at least three.
Claim 4
Dependent Claim
101 words
Apparatus as recited in claim 1 wherein said developing means further includes: a. a development station; b. drive means coupled to said first support medium for passing said latent electrostatic image through said development station; c. means for supplying developer to said development station as said latent electrostatic image is passed therethrough for developing said latent electrostatic image; and, d. wherein said control means includes means coupled to said drive means for passing said latent electrostatic image through said development station said selected number of times prior to the transfer thereof from said first support medium to said second support medium.
Claim 5
Dependent Claim
44 words
Apparatus as recited in claim 3 wherein said developer supplying means includes means for passing said developer through said development station at a velocity substantially equal to the velocity that said latent electrostatic image is passed through said development station by said drive means.
Claim 6
Dependent Claim
88 words
Apparatus as recited in claim 4 wherein said development station further includes a development plate spaced from said first support medium to define a narrow gap therebetween, at least a portion of said gap having a width of less than about 100 mils. and wherein said means for passing said developer through said development station compriseS means for dropping said developer through said gap, the narrow width of said gap causing said developer to fall at a velocity substantially equal to the velocity of said latent electrostatic image.
Claim 7
Dependent Claim
26 words
Apparatus as recited in claim 5 wherein said first support medium comprises a rotatable drum having a surface upon which said latent electrostatic image is formed.
Claim 8
Dependent Claim
14 words
Apparatus as recited in claim 6 wherein said development plate includes a knurled surface.
Claim 9
Dependent Claim
50 words
Apparatus as recited in claim 1 wherein said transfer means includes means coupled to said control means for bringing said second support medium into contact with said first support medium after said selected number of developing steps for transferring said developed image from said first medium to said second medium.
Claim 10
Dependent Claim
113 words
Electrophotographic copying apparatus comprising: a. a first support medium carrying a latent electrostatic image to be developed; b. a second support medium for receiving the developed image from said first support medium; c. means for transferring said developed image from said first support medium to said second support medium; d. developing means for developing said latent electrostatic image on said first support medium prior to the transfer thereof to said second support medium by said transfer means; and, e. control means for controlling the number of times that said latent electrostatic image is developed prior to the transfer thereof from said first support medium to said second support medium by said transfer means.
Claim 11
Dependent Claim
113 words
Electrophotographic copying apparatus comprising: a. a first support medium carrying a latent electrostatic image to be developed; b. a second support medium for receiving the developed image from said first support medium; c. means for transferring said developed image from said first support medium to said second support medium; d. developing means for developing said latent electrostatic image on said first support medium prior to the transfer thereof to said second support medium by said transfer means; and, e. control means for controlling the number of times that said latent electrostatic image is developed prior to the transfer thereof from said first support medium to said second support medium by said transfer means.
Claim 12
Dependent Claim
54 words
Apparatus as recited in claim 9 wherein said control means includes selection means for selecting the number of times that said latent electrostatic image is to be developed prior to the transfer thereof from said first support medium to said second support medium, said number of times being from one to at least two.
Claim 13
Dependent Claim
100 words
Apparatus as recited in claim 9 wherein said developing means further includes: a. a development station; b. drive means coupled to said support medium for passing said latent electrostatic image through said development station; c. means for supplying developer to said development station as said latent electrostatic image is passed therethrough for developing said latent electrostatic image; and, d. wherein said control means includes means coupled to said drive means for passing said latent electrostatic image through said development station a selected number of times prior to the transfer thereof from said first support medium to said second support medium.
Claim 14
Dependent Claim
44 words
Apparatus as recited in claim 11 wherein said developer supplying means includes means for passing said developer through said development station at a velocity substantially equal to the velocity that said latent electrostatic image is passed through said development station by said drive means.
Claim 15
Dependent Claim
88 words
Apparatus as recited in claim 12 wherein said development station further includes a development plate spaced from said support medium to define a narrow gap therebetween, at least a portion of said gap having a width of less than about 100 mils. and wherein said means for passing said developer through said development station comprises means for dropping said developer through said gap by gravity, the narrow width of said gap causing said developer to fall at velocity substantially equal to the velocity of said latent electrostatic image.
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) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |