Patent US4111702A successfully refreshed from Google Patents.
US4111702A
Expired / Lapsed
US
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Hidden entry or latent image methods and systems
Assignee: 3M Co
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Filing: 1973-01-11
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Granted: 1978-09-05
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Expires: 1993-01-11
Abstract
Abstract The disclosed paper-based feedback systems employ thermographic processes which transfer a pattern of vaporized reactant material such as dithiooxamide (DTO) or DTO derivatives to a treated or untreated paper-like receptor sheet to form a storable latent image, i.e. a hidden entry, on the sheet. The latent image can be developed weeks or months later with a co-reactant metal salt.
Inventors
- 👤 Robert D. Fraik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:13
CPC Classifications
A; A63; A63F; A63F3/00; A63F3/06; A63F3/065; A63F3/0685; B; B41; B41M; B41M5/00; B41M5/025; B41M5/035; B41M5/0356; C; C09; C09D; C09D13/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
109 words
A crayon means for dispensing an image-forming co-reactant metal salt capable of forming a colored complex with a reactant material selected from the group consisting of dithiooxamide, N,N'-disubstituted derivatives of dithiooxamide, and an iron-complexing compound capable of forming a colored complex when reacted with the ions of an iron salt, said iron-complexing compound having a benzene ring and at least two hydroxyl groups substituted in adjacent positions on said ring, said means comprising a solid wax matrix having the shape of a wax crayon, said matrix containing said coreactant material and further containing an image-forming reaction accelerator compound selected from the group consisting of trialkyl phosphates and triaryl phosphates.
Claim 2
Dependent Claim
109 words
A crayon means for dispensing an image-forming co-reactant metal salt capable of forming a colored complex with a reactant material selected from the group consisting of dithiooxamide, N,N'-disubstituted derivatives of dithiooxamide, and an iron-complexing compound capable of forming a colored complex when reacted with the ions of an iron salt, said iron-complexing compound having a benzene ring and at least two hydroxyl groups substituted in adjacent positions on said ring, said means comprising a solid wax matrix having the shape of a wax crayon, said matrix containing said coreactant material and further containing an image-forming reaction accelerator compound selected from the group consisting of trialkyl phosphates and triaryl phosphates.
Claim 3
Dependent Claim
27 words
A crayon according to claim 1 wherein the metal of said coreactant metal salt is selected from the group consisting of nickel, copper, cobalt, cadmium and iron.
Claim 4
Dependent Claim
34 words
A crayon for dispensing an image-forming, metal salt co-reactant comprising a solid wax matrix having the shape of a wax crayon, said matrix containing ferric benzoate and an image-forming reaction accelerator comprising trialkyl phosphate.
Claim 5
Dependent Claim
34 words
A crayon for dispensing an image-forming, metal salt co-reactant comprising a solid wax matrix having the shape of a wax crayon, said matrix containing ferric benzoate and an image-forming reaction accelerator comprising trialkyl phosphate.
References Cited (Backward Citations)
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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) | 1981-09-04 | 1982-03-06 | 1982-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-04 | 1986-03-06 | 1986-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-04 | 1990-03-06 | 1990-09-05 | $7700.00 | Window Closed / Lapsed |