US3520074A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Instruction system providing permanent records
Assignee: INSTRUCTION SYSTEMS Inc
•
Filing: 1967-10-04
•
Granted: 1970-07-14
•
Expires: 1987-10-04
Abstract
No abstract record available.
Inventors
- 👤 Victor G Severin
- 👤 Leonard J Kobek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 02:08
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06; G09B7/063
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2197306A
Cited
US2970385A
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US2889634A
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US3141244A
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US3177595A
Cited
US3187443A
Cited
US3206871A
Cited
FR1417753A
Cited
US3319359A
Cited
US3401470A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-07-13 | 1974-01-12 | 1974-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-07-13 | 1978-01-12 | 1978-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-07-13 | 1982-01-12 | 1982-07-14 | $7700.00 | Window Closed / Lapsed |