Patent US3726732A successfully refreshed from Google Patents.
US3726732A
Expired / Lapsed
US
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Multi-step etching projection system
Assignee: NEW FRANKLIN MINT
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Filing: 1970-07-09
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Granted: 1973-04-10
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Expires: 1990-07-09
Abstract
Abstract An optical projection system employing ultraviolet light for step projection and repeat projection of imagery to the surface of a photoresist coated coining die so that the die may be etched to various levels in registration with other projections. This permits photofabrication of dies of various sizes from a single series of step and repeat photographic negatives, each of which is in photographic registration to each other and to the respective etched surface of the coining die being fabricated. Filtered light permits visual examination of the projected imagery prior to exposure of the photoresist surface on the die. Enlargements and reductions are also possible with suitable lens systems.
Inventors
- 👤 R Richardson
- 👤 J Keegan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:13
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2022; C; C23; C23F; C23F1/00; C23F1/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
30 words
A method in accordance with claim 1 wherein said step of projecting a second image includes projecting the second image so that it at least partially overlies the first cavity.
Claim 2
Dependent Claim
29 words
A method in accordance with claim 1 including using a tool steel as the metal from which the die is made, and using an acid to etch the cavities.
Claim 3
Dependent Claim
20 words
A method in accordance with claim 1 including the step of coining coins by use of said etched die face.
Claim 4
Dependent Claim
29 words
A method in accordance with claim 1 wherein application of the photoresist material includes pouring it onto the die face while the die face rotates about a vertical axis.
Claim 5
Dependent Claim
26 words
A method in accordance with claim 1 including baking the photoresist material on the die face before each exposure, to reduce sensitivity of the photographic resist.
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) | 1976-04-09 | 1976-10-09 | 1977-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-09 | 1980-10-09 | 1981-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-09 | 1984-10-09 | 1985-04-10 | $7700.00 | Window Closed / Lapsed |