US2683652A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat treatment of microphonic carbon
Assignee: AT&T Inc
•
Filing: 1951-12-28
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Granted: 1954-07-13
•
Expires: 1971-12-28
Abstract
No abstract record available.
Inventors
- 👤 Merlin L Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:53
CPC Classifications
H; H04; H04R; H04R21/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
61 words
THE METHOD OF TREATING GRANULAR ANTHRACITE TO ADAPT IT FOR MICROPHONIC TRANSMISSION WHICH COMPRISES ROASTING ANTHRACITE IN A NON-OXIDIZING ATMOSPHERE AT FROM ABOUT 800 TO 1400* C., COOLING THE ROASTED ANTHRACITE IN THE NON-OXIDIZING ATMOSPHERE TO BELOW ABOUT 500* C., AND MAINTAINING THE ROASTED ANTHRACITE AT FROM ABOUT 250 TO 500* C. IN AN OXIDIZING ATMOSPHERE FOR AT LEAST AN HOUR.
Claim 2
Independent Claim
61 words
THE METHOD OF TREATING GRANULAR ANTHRACITE TO ADAPT IT FOR MICROPHONIC TRANSMISSION WHICH COMPRISES ROASTING ANTHRACITE IN A NON-OXIDIZING ATMOSPHERE AT FROM ABOUT 800 TO 1400* C., COOLING THE ROASTED ANTHRACITE IN THE NON-OXIDIZING ATMOSPHERE TO BELOW ABOUT 500* C., AND MAINTAINING THE ROASTED ANTHRACITE AT FROM ABOUT 250 TO 500* C. IN AN OXIDIZING ATMOSPHERE FOR AT LEAST AN HOUR.
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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) | 1957-07-12 | 1958-01-11 | 1958-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-07-12 | 1962-01-11 | 1962-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-07-12 | 1966-01-11 | 1966-07-13 | $7700.00 | Window Closed / Lapsed |