US4748147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Writing set
Assignee: Sakura Color Products Corp
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Filing: 1985-11-29
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Granted: 1988-05-31
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Expires: 2005-11-29
Abstract
Abstract A writing set comprising a combination of paper printed thereon with two or more coloring bands using two or more types of leuco dye which develop different colors and a writing means which contains a solution of acid materials which develops the color of the leuco dyes. When characters, pictures, etc. are written on the paper, the colorless leuco dyes in the written portion develop color to form colorful characters, pictures, etc.
Inventors
- 👤 Masa-aki Sumi-i
- 👤 Hikoshiro Nushimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:00
CPC Classifications
B; B41; B41M; B41M3/00; B41M3/001; B44; B44D; B44D3/00; B44D3/18
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
75 words
A combination writing device comprising a sheet substrate having printed thereon a plurality of proximate areas of different color leuco dyes in an undeveloped colorless state and a writing instrument containing a dye developing composition including and acid solution whereby when said writing instrument is drawn over said substrate along any desired path said dyes are developed along said path in accordance with the traversed dye areas to produce correspondingly colored image of said path.
Claim 2
Dependent Claim
75 words
A combination writing device comprising a sheet substrate having printed thereon a plurality of proximate areas of different color leuco dyes in an undeveloped colorless state and a writing instrument containing a dye developing composition including and acid solution whereby when said writing instrument is drawn over said substrate along any desired path said dyes are developed along said path in accordance with the traversed dye areas to produce correspondingly colored image of said path.
Claim 3
Dependent Claim
18 words
The combination of claim 1 wherein said proximate dye areas are contiguous bands of said undeveloped leuco dyes.
Claim 4
Dependent Claim
13 words
A writing set as claimed in claim 2 wherein said bands are linear.
Claim 5
Dependent Claim
14 words
A writing set as claimed in claim 2 wherein said bands form wavy curve.
Claim 6
Dependent Claim
14 words
A writing set as claimed in claim 2 wherein said bands form concentric curves.
Claim 7
Dependent Claim
30 words
A writing set as claimed in any of claims 2 to 5 wherein said bands are printed with solutions of said undeveloped leuco dyes all over the surface of paper.
Claim 8
Dependent Claim
23 words
A writing set as claimed in any of claims 2 to 5 wherein a mark is attached to each boundary of parallel bands.
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) | 1991-05-31 | 1991-11-30 | 1992-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-31 | 1995-11-30 | 1996-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-31 | 1999-11-30 | 2000-05-31 | $7700.00 | Window Closed / Lapsed |