Patent US4444874A successfully refreshed from Google Patents.
US4444874A
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Photographic elements containing direct-positive emulsions and processes for their use
Assignee: Eastman Kodak Co
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Filing: 1982-09-15
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Granted: 1984-04-24
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Expires: 2002-09-15
Abstract
Abstract Photographic elements particularly adapted for forming direct-positive images are disclosed in which a radiation-sensitive core-shell emulsion layer and a silver halide emulsion layer incapable of forming a surface latent image within the direct-positive exposure latitude of the first emulsion layer and containing a grain population capable of internally trapping photolytically generated electrons are both present. The photographic elements are capable of exhibiting increased covering power, greater maximum density, and increased speed.
Inventors
- 👤 Robert A. Silverman
- 👤 Harry A. Hoyen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:17
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/005; G03C1/485; G03C1/48538; G03C1/48569; Y; Y10; Y10S; Y10S430/00; Y10S430/141
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
114 words
A photographic element particularly adapted to forming a direct-positive image comprised of a support and, located on said support, a first, radiation-sensitive emulsion layer containing core-shell silver halide grain population having a coefficient of variation of less than 20%, and a second silver halide emulsion layer substantially incapable of forming a surface latent image within the direct-positive exposure latitude of the first emulsion layer and containing a second grain population capable of internally trapping photolytically generated electrons, said second grain population having an average diameter less than 70% that of said first grain population, and said first and second silver halide grain populations being present in a weight ratio of from 5:1 to 1:5.
Claim 2
Dependent Claim
114 words
A photographic element particularly adapted to forming a direct-positive image comprised of a support and, located on said support, a first, radiation-sensitive emulsion layer containing core-shell silver halide grain population having a coefficient of variation of less than 20%, and a second silver halide emulsion layer substantially incapable of forming a surface latent image within the direct-positive exposure latitude of the first emulsion layer and containing a second grain population capable of internally trapping photolytically generated electrons, said second grain population having an average diameter less than 70% that of said first grain population, and said first and second silver halide grain populations being present in a weight ratio of from 5:1 to 1:5.
Claim 3
Dependent Claim
14 words
A photographic element according to claim 1 additionally including a nucleating agent incorporated therein.
Claim 4
Dependent Claim
24 words
A photographic element according to claim 1 wherein said first, core-shell grain population is sensitized with at least one of sulfur, selenium, and gold.
Claim 5
Dependent Claim
21 words
A photographic element according to claim 1 wherein said second silver halide grain population is comprised of core-shell silver halide grains.
Claim 6
Dependent Claim
23 words
A photographic element according to claim 4 wherein said core-shell grains of said second grain population are substantially free of surface chemical sensitization.
Claim 7
Dependent Claim
22 words
A photographic element according to claim 1 wherein at least said core-shell grains of said first grain population are comprised of bromide.
Claim 8
Dependent Claim
19 words
A photographic element according to claim 6 wherein said bromide containing silver halide grains are additionally comprised of iodide.
Claim 9
Dependent Claim
25 words
A photographic element according to claim 1 wherein said second grain population has an average diameter less than 50% that of said first grain population.
Claim 10
Dependent Claim
25 words
A photographic element according to claim 8 wherein said second grain population has an average diameter less than 40% total of said first grain population.
Claim 11
Dependent Claim
27 words
A photographic element according to claim 1 wherein said first and second silver halide grain populations are present in a weight ratio of from 2:1 to 1:3.
Claim 12
Dependent Claim
18 words
A photographic element according to claim 1 wherein said first, core-shell grain population is comprised of tabular grains.
Claim 13
Dependent Claim
55 words
A photographic element according to claim 11 wherein said grains of said first grain population having a thickness of less than 0.5 micron and a diameter greater than 0.6 micron have an average aspect ratio greater than 8:1 and account for greater than 50% of the total projected surface area of said first grain population.
Claim 14
Dependent Claim
20 words
A photographic element according to claim 1 wherein said second emulsion layer nearer said support than said first emulsion layer.
Claim 15
Dependent Claim
16 words
A photographic element according to claim 13 wherein said first emulsion layer contains a nucleating agent.
Claim 16
Dependent Claim
31 words
A photographic element according to claim 1 wherein said second emulsion layer is positioned to be contacted during processing with a nucleating agent no later than being contacted with an antifoggant.
Claim 17
Dependent Claim
25 words
A photographic element according to claim 15 wherein said second emulsion layer contains a nucleating agent adsorbed to the surfaces of said second grain population.
Claim 18
Dependent Claim
31 words
A photographic element according to claim 1 in which said second core-shell grain population increases the minimum density of said emulsion layers to no more than 20% of their maximum density.
Claim 19
Dependent Claim
38 words
A photographic element according to claim 1 in which said first core-shell grain population contains a divalent or trivalent metal ion chosen from the group consisting of cadmium, lead, and erbium in an amount sufficient to reduce rereversal.
Claim 20
Dependent Claim
37 words
A photographic element according to claim 1 in which said first core-shell grain population exhibits a coefficient of variation of less than 10% and said photographic element is capable of producing a contrast of greater than 10.
Claim 21
Dependent Claim
31 words
A photographic element according to claim 1 in which said second core-shell grain population increases the minimum density of the photographic element to no more than 5% of its maximum density.
Claim 22
Dependent Claim
21 words
A photographic element according to claim 1 in which said second grain population is comprised of converted halide silver halide grains.
Claim 23
Dependent Claim
21 words
A photographic element according to claim 1 in which said second grain population is comprised of internally fogged silver halide grains.
Claim 24
Dependent Claim
39 words
Processing in a surface developer an imagewise exposed photographic element according to any one of claims 1 through 22 (a) in the presence of a nucleating agent, or (b) with light flashing of the exposed photographic element during processing.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-04-24 | 1987-10-24 | 1988-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-24 | 1991-10-24 | 1992-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-24 | 1995-10-24 | 1996-04-24 | $7700.00 | Window Closed / Lapsed |