US4839751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Track-following servo for disk drive with multiple reference windows and time dependent logic circuitry
Assignee: Unisys Corp
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Filing: 1987-03-10
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Granted: 1989-06-13
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Expires: 2007-03-10
Abstract
Abstract Disclosed is a Fine positioning arrangement for track-follow servo means in a disk drive arrangement wherein servo head output is processed logically to indicate violation by the head of a near-boundry or a far-boundry for prescribed times to indicate whether the transducer is truly "on-center" or not and to logically exclude noise and other error conditions that might compromise this indication.
Inventors
- 👤 William R. Revels
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:15
CPC Classifications
G; G11; G11B; G11B21/00; G11B21/02; G11B21/10; G11B21/106; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59605
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
198 words
A disk drive servo system for controlling positioning of a servo actuator, based, in part, on servo signals "ss" from servo transducer means T S , read-out from recorded servo data, this system including: a plurality of servo referencing means R n , each adapted to indicate whether said transducer means T s has deviated from track-center T-C by one of several different respective deviation-distances ±dn, each referencing means R n , being arranged and adapted to issue a respective positive output deviation signal S n , indicating that transducer means has so deviated beyond its respective deviation distance ±dn, or to issue a negative output deviation signal Sn indicating that it has not so deviated; a plurality of timer stages TT n , each adapted to receive a respective deviation signal Sn or Sn and each issue a respective deviation-time output signal t-S n indicating that a respective positive deviation Sn has been continuously applied thereto for a prescribed respective time t n ; and logic circuit means, including a logic output stage L-0 adapted to issue negative output signals f-p indicating that said transducer means T s is OFF-CENTER as defined by the logic circuit means.
Claim 2
Dependent Claim
198 words
A disk drive servo system for controlling positioning of a servo actuator, based, in part, on servo signals "ss" from servo transducer means T S , read-out from recorded servo data, this system including: a plurality of servo referencing means R n , each adapted to indicate whether said transducer means T s has deviated from track-center T-C by one of several different respective deviation-distances ±dn, each referencing means R n , being arranged and adapted to issue a respective positive output deviation signal S n , indicating that transducer means has so deviated beyond its respective deviation distance ±dn, or to issue a negative output deviation signal Sn indicating that it has not so deviated; a plurality of timer stages TT n , each adapted to receive a respective deviation signal Sn or Sn and each issue a respective deviation-time output signal t-S n indicating that a respective positive deviation Sn has been continuously applied thereto for a prescribed respective time t n ; and logic circuit means, including a logic output stage L-0 adapted to issue negative output signals f-p indicating that said transducer means T s is OFF-CENTER as defined by the logic circuit means.
Claim 3
Dependent Claim
87 words
The invention of claim 1 where at least two such deviation-distances ±d 1 , ±d 2 , are so established, with associated referencing means R 1 , R 2 ; respective outputs S 1 or S 1 and S 2 or S 2 , therefrom; and with associated respective timer stages TT, TT 2 adapted to issue respective output signals T-S, T-S 2 , representing presence of a respective deviation-indicating signal S 1 , S 2 for a respective time period T 1 , T 2 .
Claim 4
Dependent Claim
58 words
The invention of claim 2 where output stage L-0 comprises gate means adapted to issue said OFF-CENTER indicating signals f-p when transducer T s deviates by ±d, for T 1 seconds; or when T s deviates by ±d 2 for T 2 seconds, where ±d 3 >±d 2 , and thereafter T s further deviates by ±d, also.
Claim 5
Dependent Claim
40 words
The invention of claim 3 where the system is farther adapted and arranged to NOT issue ON-CENTER output signals f-p, but to issue OFF-CENTER output signals f-p, unless and until transducer means T s comes with ±d, of absolute track-center.
Claim 6
Dependent Claim
27 words
The invention of claim 4 where the system is further arranged and adapted to apply said OFF-CENTER output signals f-p to inhibit operation of associated recording means.
Claim 7
Dependent Claim
34 words
The invention of claim 5 where are included write-control means W-C whereby said OFF-CENTER output signals f-p, or contrary ON-CENTER output signals f-p, are applied to inhibit said recording means, or to enable it.
Claim 8
Dependent Claim
12 words
The invention of claim 6 wherein said Write-Control means W-C is microprocessor.
Claim 9
Dependent Claim
19 words
The invention of claim 1 where said referencing means each comprise a like comparator circuit together with reference-signal means.
Claim 10
Dependent Claim
42 words
The invention of claim 5 where said deviation-indicating signals S 1 , S 2 are logically combined to set an output-latch means LL o and said output stage L-0 comprises gate means controlled, in part, by said latch means LL o .
Claim 11
Dependent Claim
23 words
The invention of claim 9 where said distance d 1 constitutes several dozen uin. and d 2 is at least l.25d 1 .
Claim 12
Dependent Claim
150 words
A disk drive servo system for controlling positioning of a servo actuator, based, in part, on servo signals "ss" from servo transducer means T S , read-out from recorded servo data, this system including: a plurality of servo referencing means R n , each adapted to indicate whether said transducer means T s has deviated from track-center T-C by one of several different respective deviation-distances dn, each referencing means R n , being arranged and adapted to issue a respective positive output deviation signal S n , indicating that transducer means has so deviated beyond its respective deviation distance dn, and to issue a negative output deviation signal Sn indicating that it has not so deviated; and output-logic means adapted to receive and combine the outputs S n , S n of said referencing means, process them and responsively indicate the "on-track" status of said transducer means T s .
Claim 13
Dependent Claim
150 words
A disk drive servo system for controlling positioning of a servo actuator, based, in part, on servo signals "ss" from servo transducer means T S , read-out from recorded servo data, this system including: a plurality of servo referencing means R n , each adapted to indicate whether said transducer means T s has deviated from track-center T-C by one of several different respective deviation-distances dn, each referencing means R n , being arranged and adapted to issue a respective positive output deviation signal S n , indicating that transducer means has so deviated beyond its respective deviation distance dn, and to issue a negative output deviation signal Sn indicating that it has not so deviated; and output-logic means adapted to receive and combine the outputs S n , S n of said referencing means, process them and responsively indicate the "on-track" status of said transducer means T s .
Claim 14
Dependent Claim
28 words
The system of claim 11, wherein said logic means is arranged and adapted to exclude noise and other error conditions apt to comprise this indication of "on-track" status.
References Cited (Backward Citations)
US4553182A
Cited
US4734851A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-12 | 1992-12-12 | 1993-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-12 | 1996-12-12 | 1997-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-12 | 2000-12-12 | 2001-06-13 | $7700.00 | Window Closed / Lapsed |