Patent US4309255A successfully refreshed from Google Patents.
US4309255A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrochromic recording paper
Assignee: IBM Information Products Corp
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Filing: 1980-09-10
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Granted: 1982-01-05
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Expires: 2000-09-10
Abstract
Abstract A medium for electrochromic recording is provided by treating paper with a water soluble leuco methylene blue compound having the formula ##STR1## wherein R is a sulfonated aromatic or sulfonated aliphatic moiety.
Inventors
- 👤 Paul L. Gendler
- 👤 Barbara D. Grant
- 👤 Clinton D. Snyder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:02
CPC Classifications
B; B41; B41M; B41M5/00; B41M5/20
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
23 words
A substrate for use in electrochromic recording comprising paper containing a water soluble leuco methylene blue compound which is a salt of 3,7-bis-(dimethylamino)-10-(2-sulfobenzoyl)-phenothiazine.
Claim 2
Dependent Claim
23 words
A substrate for use in electrochromic recording comprising paper containing a water soluble leuco methylene blue compound which is a salt of 3,7-bis-(dimethylamino)-10-(2-sulfobenzoyl)-phenothiazine.
Claim 3
Dependent Claim
22 words
A substrate as claimed in claim 1 wherein the paper contains approximately 10 mg of leuco methylene blue material per standard page.
Claim 4
Dependent Claim
21 words
A substrate as claimed in claim 1 wherein the water soluble leuco methylene blue compound is the potassium salt of 3,7-bis-(dimethylamino)-10-(2-sulfobenzoyl)-phenothiazine.
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) | 1985-01-04 | 1985-07-06 | 1986-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-01-04 | 1989-07-06 | 1990-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-01-04 | 1993-07-06 | 1994-01-05 | $7700.00 | Window Closed / Lapsed |