US4907903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Representing utensil
Assignee: Individual
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Filing: 1988-08-16
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Granted: 1990-03-13
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Expires: 2008-08-16
Abstract
Abstract A representing utensil for use in making an invisibly depicted matter visible again which houses a coloring assistant in its own container is disclosed, wherein the coloring assistant is able to make a colorlessly depicted matter develop color and, after its coloring, do the short-time fading at which time the color is losen of itself in a relatively short time by acting on the depicted matter with the aid of a coloring agent, and further is able to make the depicted matter do repeat the recoloring and the short-time fading each time when the coloring assistant acts on the depicted matter a plural number of times.
Inventors
- 👤 Kiyoharu Kawashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:27
CPC Classifications
G; G09; G09B; G09B3/00; G09B3/02; G09B3/04; C; C09; C09D; C09D11/00; C09D11/50
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
70 words
Representing utensil containing a coloring assistant, in its own container, for repeatedly developing color of a depicted matter which is invisibly depicted with a coloring agent including an alkaline ph-indicator; wherein said container is provided with activated charcoal therein, and said coloring assistant consists of 4 to 20 weight % N,N-dimethylethanol amine, 0.05 to 3 weight % of citric acid, 0.05 to 3 weight % of sodium chloride, and water.
Claim 2
Dependent Claim
70 words
Representing utensil containing a coloring assistant, in its own container, for repeatedly developing color of a depicted matter which is invisibly depicted with a coloring agent including an alkaline ph-indicator; wherein said container is provided with activated charcoal therein, and said coloring assistant consists of 4 to 20 weight % N,N-dimethylethanol amine, 0.05 to 3 weight % of citric acid, 0.05 to 3 weight % of sodium chloride, and water.
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) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |