US3740736A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spiral recording with error checking
Assignee: Memorex Corp
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Filing: 1972-02-28
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Granted: 1973-06-19
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Expires: 1992-02-28
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
2026-11-06 04:06
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/36
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
133 words
A disc certifier comprising: a spindle for supporting a magnetic recording disc and rotating the disc about a central axis, a carriage mounted adjacent to the spindle for movement generally radially of said axis, three magnetic recording heads mounted on said carriage adjacent to each other and adapted to be positioned over the same recordIng surface of the disc with the heads mounted on the carriage in fixed position with respect to each other at substantially equal radii from said axis, drive means for moving said carriage continuously radially of the axis while a disc is rotating on the spindle to move the recording heads along a continuous spiral path over the disc, and control means connected to said recording heads for writing data with one head and reading with the other heads.
Claim 2
Dependent Claim
133 words
A disc certifier comprising: a spindle for supporting a magnetic recording disc and rotating the disc about a central axis, a carriage mounted adjacent to the spindle for movement generally radially of said axis, three magnetic recording heads mounted on said carriage adjacent to each other and adapted to be positioned over the same recordIng surface of the disc with the heads mounted on the carriage in fixed position with respect to each other at substantially equal radii from said axis, drive means for moving said carriage continuously radially of the axis while a disc is rotating on the spindle to move the recording heads along a continuous spiral path over the disc, and control means connected to said recording heads for writing data with one head and reading with the other heads.
Claim 3
Dependent Claim
62 words
The apparatus of claim 1 characterized further by the inclusion of D.C. erase means mounted adjacent to the path of discs on the spindle for D.C. erasing the recording layer on the disc before the recording layer reaches the three heads whereby the first head reading the erased disc detects extra bits and the second head reading the disc detects missing bits.
Claim 4
Dependent Claim
123 words
The apparatus of claim 1 in which: said recording heads are flying heads adapted to be supported over the disc on an air-bearing layer generated by rotation of the disc, and said drive means comprises a cam for limiting the radially inward movement of the carriage, a cam follower mounted on the carriage and engaging the cam means for moving the cam with respect to the axis of the spindle to permit the carriage to approach the axis, and a voice coil motor connected to the carriage for urging the carriage toward the axis thereby keeping the cam follower on the cam with the voice coil motor adapted to pull the carriage away from the axis separating the cam follower from the cam.
Claim 5
Dependent Claim
97 words
The apparatus of claim 2 in which said control means comprises: an integrator connected to the second reading head for generating a comparison signal which is a parameter of the average signal output of the second head over a substantial length of said spiral path, a drop-out comparator connected to the integrator and the second reading head for comparing the instantaneous output of the second head to the comparison signal, and a noise comparator connected to the integrator and the first reading head for comparing the instantaneous output of the first reading head to the comparison signal.
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) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |