US3890148A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure of light-sensitive materials
Assignee: Howson Algraphy Ltd
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Filing: 1973-02-15
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Granted: 1975-06-17
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Expires: 1993-02-15
Abstract
Abstract In a method of exposing light sensitive materials, particularly positive working presensitised lithographic printing plates, an additional exposure is given either before, or after, the imagewise exposure. The additional exposure is given using a mask provided with a light-transmitting pattern conforming to those areas of the light sensitive material which are not struck by light during the image-wise exposure but which are desired to be struck by light. The mask comprises a light transmitting sheet coated with a non-light transmitting composition and the lighttransmitting pattern is produced by treating parts of the coating with a liquid.
Inventors
- 👤 Leslie Edward Lawson
- 👤 Peter John Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:39
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2022
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
125 words
A METHOD OF EXPOSING A LAYER OF POSITIVE-WORKING PHOTOSENSITIVE MATERIAL WHICH COMPRISES ASSEMBLING TOGETHER A PLURALITY OF POSITIVE FILMS TO PRODUCE AN IMAGE, PREPARING A MASK BY PROVIDING A SHEET OF ACTINIC LIGHT TRANSMITTING MATERIAL COATED WITH A COMPOSITION WHICH DOES NOT TRANSMIT ACTINIC LIGHT, SAID COATED SHEET BEING VISIBLE LIGHT TRANSMITTING, AND PAINTING PARTS OF SAID COMPOSITION WITH A LIQUID WHICH INTERACTS WITH SAID COMPOSITION TO PERMITACTINIC LIGHT TO BE TRANSMITTED THROUGH SAID SHEET AND THEREBY TO FORM ON THE SHEET AN ACTINIC LIGHT TRANSMITTING PATTERN CORRESPONDING TO THE PATTERN DEFINED BY THE EDGES OF THE FILMS IN THE ASSEMBLY, AND EXPOSING THE LAYERS TO ACTINIC LIGHT THROUGH SAID MASK EITHER BEFORE OR AFTER SUBJECTING THE LAYER TO AN IMAGE-FORMING EXPOSURE THROUGH THE ASSEMBLY.
Claim 2
Independent Claim
125 words
A METHOD OF EXPOSING A LAYER OF POSITIVE-WORKING PHOTOSENSITIVE MATERIAL WHICH COMPRISES ASSEMBLING TOGETHER A PLURALITY OF POSITIVE FILMS TO PRODUCE AN IMAGE, PREPARING A MASK BY PROVIDING A SHEET OF ACTINIC LIGHT TRANSMITTING MATERIAL COATED WITH A COMPOSITION WHICH DOES NOT TRANSMIT ACTINIC LIGHT, SAID COATED SHEET BEING VISIBLE LIGHT TRANSMITTING, AND PAINTING PARTS OF SAID COMPOSITION WITH A LIQUID WHICH INTERACTS WITH SAID COMPOSITION TO PERMITACTINIC LIGHT TO BE TRANSMITTED THROUGH SAID SHEET AND THEREBY TO FORM ON THE SHEET AN ACTINIC LIGHT TRANSMITTING PATTERN CORRESPONDING TO THE PATTERN DEFINED BY THE EDGES OF THE FILMS IN THE ASSEMBLY, AND EXPOSING THE LAYERS TO ACTINIC LIGHT THROUGH SAID MASK EITHER BEFORE OR AFTER SUBJECTING THE LAYER TO AN IMAGE-FORMING EXPOSURE THROUGH THE ASSEMBLY.
Claim 3
Dependent Claim
19 words
A method as claimed in claim 1, wherein the composition comprises a binder and an actinic light absorbing dye.
Claim 4
Dependent Claim
26 words
A method according to claim 2, wherein said dye is a bleachable dye and said liquid is a bleaching agent capable of rendering the dye colourless.
Claim 5
Dependent Claim
15 words
A method according to claim 2, wherein said liquid is a solvent for the binder.
Claim 6
Dependent Claim
22 words
A method according to claim 2, wherein said binder is an alkali soluble resin and the said liquid is an alkaline liquid.
Claim 7
Dependent Claim
19 words
A method according to claim 1, wherEin said sheet of actinic light transmitting material is formed of polyethylene terephthalate.
Claim 8
Dependent Claim
27 words
A METHOD ACCORDING TO CLAIM 1, WHEREIN THE LAYER OF PHOTO-SENSITIVE MATERIAL FORMS PART OF A PHOTO-SENSITIVE PLATE SUITABLE FOR THE PRODUCTION OF A LITHOGRAPHIC PRINTING PLATE.
Claim 9
Dependent Claim
14 words
A method according to claim 1, wherein the photo-sensitive material is a quinone diazide.
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) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |