US4578721A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stress test for magnetic disc recording apparatus
Assignee: Seagate Technology LLC
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Filing: 1984-09-10
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Granted: 1986-03-25
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Expires: 2004-09-10
Abstract
Abstract Method and apparatus for testing tracking accuracy in a disc drive are disclosed. Each head and each track is treated as a unique entity. Each track has an inherent window margin. Stored data is read by a head skewed (or delayed) in the window toward one edge of the window until errors are encountered. The data is then advanced toward the center 5% of the bit cell past the point at which errors are not encountered. With the data positioned in the window 5% from it's failure point, any noise or media defects will cause the data bits to fall out of the window and thus cause an error. Any soft errors that repeat in the same byte area are logged as hard errors. This testing method accomplishes both a defect mapping test and soft error rate test in one test in the least amount of time from the interface.
Inventors
- 👤 William L. Brannan, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:40
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/18; G11B20/1816
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
130 words
Apparatus for evaluating recording systems including means coupled to said head for reading data from one of said tracks, means for generating a succession of data windows having leading and trailing edges, a data separator connected to receive said data windows and the read data and serving to separate out data which falls outside the windows, and means for delaying said data from each track on the disc relative to at least one edge of said data windows to provide a more limited effective size window at said separator for testing the effective separation of the data, said delaying means including means for delaying the data until errors are encountered to define a failure point, and for reducing the data delay to a time just less than the failure point.
Claim 2
Dependent Claim
130 words
Apparatus for evaluating recording systems including means coupled to said head for reading data from one of said tracks, means for generating a succession of data windows having leading and trailing edges, a data separator connected to receive said data windows and the read data and serving to separate out data which falls outside the windows, and means for delaying said data from each track on the disc relative to at least one edge of said data windows to provide a more limited effective size window at said separator for testing the effective separation of the data, said delaying means including means for delaying the data until errors are encountered to define a failure point, and for reducing the data delay to a time just less than the failure point.
Claim 3
Dependent Claim
42 words
Apparatus as in claim 1 including means for providing different relative positions between at least one edge of said window and said data, said delay reducing means comprising means for delaying the data to a point within 5% of the failure point.
Claim 4
Independent Claim
97 words
The method of evaluating a recording system which includes passing the data reproduced from each track of a disc drive in said system comprising reading data recorded on each track of said drive, delaying the data read from each track a variable amount, generating a succession of data windows, comparing the read data which occurs within the windows with the raw data recorded on the tracks, comparing the read data with the raw data until a significant error level occurs, reducing the delay on said read data, and rereading said recorded data to generate an error rate.
Claim 5
Independent Claim
97 words
The method of evaluating a recording system which includes passing the data reproduced from each track of a disc drive in said system comprising reading data recorded on each track of said drive, delaying the data read from each track a variable amount, generating a succession of data windows, comparing the read data which occurs within the windows with the raw data recorded on the tracks, comparing the read data with the raw data until a significant error level occurs, reducing the delay on said read data, and rereading said recorded data to generate an error rate.
Claim 6
Dependent Claim
22 words
The method of claim 3 wherein said data is delayed at said rereading step to within about 5% of the failure point.
Claim 7
Dependent Claim
43 words
The method of claim 3 wherein the step of reducing the delay on said read data includes delaying the data until errors are encountered to define a failure point, and reducing the data delay to a time just less than the failure point.
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) | 1989-03-24 | 1989-09-23 | 1990-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-24 | 1993-09-23 | 1994-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-24 | 1997-09-23 | 1998-03-25 | $7700.00 | Window Closed / Lapsed |