US3521630A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Respirator face mask with replaceable filter
Assignee: 3M Co
•
Filing: 1967-04-07
•
Granted: 1970-07-28
•
Expires: 1987-04-07
Abstract
No abstract record available.
Inventors
- 👤 Walter M Westberg
- 👤 Patrick H Carey Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:07
CPC Classifications
A; A62; A62B; A62B23/00; A62B23/02; A62B23/025
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
CA673268A
Cited
US1925764A
Cited
US3137296A
Cited
US3170461A
Cited
US3330273A
Cited
US3333585A
Cited
US3388651A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-07-27 | 1974-01-26 | 1974-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-07-27 | 1978-01-26 | 1978-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-07-27 | 1982-01-26 | 1982-07-28 | $7700.00 | Window Closed / Lapsed |