Patent US3781835A successfully refreshed from Google Patents.
US3781835A
Expired / Lapsed
US
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Method of certifying magnetic recording disc
Assignee: Memorex Corp
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Filing: 1973-02-16
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Granted: 1973-12-25
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Expires: 1993-02-16
Abstract
Abstract A certifier for computer disc memories in which a voice coil motor drives cam loaded read-write flying heads radially across a disc restrained by a control cam so that the heads follow a single continuous spiral path over the disc. Three read-write heads examine the disc at a test location on the spiral after D.C. erasure to read for extra bits, write data and read for missing bits. Error comparisons are made against a one revolution integration of the output of the data read head. A modulation test compares the one revolution integration of data head output to a part revolution integration of the data head output.
Inventors
- 👤 C Dion
- 👤 D Maruyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:05
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/1207
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
108 words
The method of certifying a magnetic recording disc which comprises: D.C. erasing the disc; and then continuously along a continuous spiral path on the disc, and at a single test station, reading the magnetic recording disc which has been D.C. erased to generate a noise signal, writing data on the disc, and reading the data which has been written on the disc to generate a data signal; integrating the data signal over a predetermined time interval to generate a comparison signal; comparing the comparison signal to the data signal to detect missing data bits; and comparing the comparison signal to the noise signal to detect extra data bits.
Claim 2
Independent Claim
108 words
The method of certifying a magnetic recording disc which comprises: D.C. erasing the disc; and then continuously along a continuous spiral path on the disc, and at a single test station, reading the magnetic recording disc which has been D.C. erased to generate a noise signal, writing data on the disc, and reading the data which has been written on the disc to generate a data signal; integrating the data signal over a predetermined time interval to generate a comparison signal; comparing the comparison signal to the data signal to detect missing data bits; and comparing the comparison signal to the noise signal to detect extra data bits.
Claim 3
Dependent Claim
55 words
The method of claim 1 characterized further by the inclusion of the steps of integrating the data signal over a second predetermined time interval substantially shorter than the first predetermined time interval to generate a modulation test signal, and comparing the comparison signal to the modulation test signal to detect inherent modulation in the disc.
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) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |