US3619265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rare earth oxide having inert layer thereon and method of making same
Assignee: GTE Sylvania Inc
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Filing: 1969-02-28
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Granted: 1971-11-09
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Expires: 1989-02-28
Abstract
Abstract A rare earth oxide host phosphor has incorporated thereon an outer layer of chemically combined fluoride ion. The coating increases the adherence properties of the phosphor in slurry application techniques for the manufacture of television screens by preventing poisoning of the phosphor particles by dichromate ions present in the slurry. The phosphor is coated by batching in a .05 molar fluoride bath, in acidic solution, about 400 to 500 grams of phosphor per liter of solution, agitating for about 20 to 30 minutes, and decanting the acidic solution, washing and then filtering and drying the phosphor. The drying temperature should be less than 200* C. to prevent disruption of the coating.
Inventors
- 👤 Michael J Hammond
- 👤 Raymond F Herner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:21
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7701
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
17 words
The invention of claim 1 wherein said drying step is carried out at less than 200* C.
Claim 2
Dependent Claim
13 words
The invention of claim 2 wherein said drying temperature is approximately 125* C.
Claim 3
Dependent Claim
10 words
The invention of claim 1 wherein said solution is NH4F.HF.
Claim 4
Dependent Claim
23 words
The invention of claim 1 wherein said phosphor is selected from the group consisting essentially of yttrium oxide, gadolinium oxide, and yttrium-gadolinium oxide.
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) | 1974-11-08 | 1975-05-10 | 1975-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-08 | 1979-05-10 | 1979-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-08 | 1983-05-10 | 1983-11-09 | $7700.00 | Window Closed / Lapsed |