Method and apparatus for eliminating apparent offset in the servo code in a magnetic disc drive
Abstract
This method and apparatus for eliminating apparent offset in the servo code adjacent to a guard band on a magnetic memory disc utilizes at least two phases of servo code per magnetic cell for seeking and track centering, or track following, operations and two phases of guard band code per magnetic cell. The two phases of guard band code are each either in phase or similarly out of phase with the respective phases of the servo code in individual magnetic cells. Phase lacking on a selected phase of guard band code is achieved by providing a synchronizing code in the guard band using an irregular pattern of guard band code, providing a timing signal count representing a cell count, for example, decoding the synchronizing code to provide an end of code signal and utilizing the end of code signal and a predetermined cell count signal to achieve phase locking on the correct phase of the guard band code.

Term
Term ended
Projected expiry passed 3 April 2007, 19.5 years ago.
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- Filed
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- Projected expiry
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1 sheet
Sheet 1
7 members in 5 offices
Priority claims4
| Document | Office | Kind | Date |
|---|---|---|---|
| 858996 | United States of America | – | |
| 85899686 | United States of America | A | |
| 858996 | – | – | – |
| US19860858996 | – | – | – |
Members7
| Document | Office | Kind | |
|---|---|---|---|
| US4669003A | United States of America | A | |
| EP0243729A2 | European Patent Office (EPO) | A2 | |
| JPS62264487A | Japan | A | |
| EP0243729A3This record | European Patent Office (EPO) | A3 | |
| EP0243729B1 | European Patent Office (EPO) | B1 | |
| DE3774475D1 | Germany | D1 | |
| CA1295419C | Canada | C |
24 legal events, as 2 offices reported them to INPADOC
Over the term
Point at a mark for the eventEvents
| Event | Code | Office | |
|---|---|---|---|
| Lapsed in a contracting state [announced via postgrant information from national office to epo]LapsedPG25 | PG25 | EP | |
| Notification of lapseLapsedST | ST | FR | |
| Lapsed in a contracting state [announced via postgrant information from national office to epo]LapsedPG25 | PG25 | EP | |
| Lapsed in a contracting state [announced via postgrant information from national office to epo]LapsedPG25 | PG25 | EP | |
| Gb: european patent ceased through non-payment of renewal feeCeasedGBPC | GBPC | EP | |
| Lapsed in a contracting state [announced via postgrant information from national office to epo]LapsedPG25 | PG25 | EP | |
| No opposition filedOpposition26N | 26N | EP | |
| No opposition filed within time limitOppositionORIGINAL CODE: 0009261PLBE | PLBE | EP | |
| Information on the status of an ep patent application or granted ep patentGrantedSTATUS: NO OPPOSITION FILED WITHIN TIME LIMITSTAA | STAA | EP | |
| Annual fee paid to national office [announced via postgrant information from national office to epo]GrantedPGFP | PGFP | EP | |
| Annual fee paid to national office [announced via postgrant information from national office to epo]GrantedPGFP | PGFP | EP | |
| Annual fee paid to national office [announced via postgrant information from national office to epo]GrantedPGFP | PGFP | EP | |
| It: translation for a ep patent filedITF | ITF | EP | |
| It: translation for a ep patent filedITF | ITF | EP | |
| Fr: translation filedET | ET | EP | |
| Corresponds to:REF | REF | EP | |
| Designated contracting statesAK | AK | EP | |
| (expected) grantORIGINAL CODE: 0009210GRAA | GRAA | EP | |
| First examination report despatched17Q | 17Q | EP | |
| Request for examination filed17P | 17P | EP | |
| Designated contracting statesAK | AK | EP | |
| Search report despatchedORIGINAL CODE: 0009013PUAL | PUAL | EP | |
| Designated contracting statesAK | AK | EP | |
| Public reference made under article 153(3) epc to a published international application that has entered the european phaseORIGINAL CODE: 0009012PUAI | PUAI | EP |
Numbers
- Publication
- 0243729
- Publication, DOCDB
- 0243729
- Publication, EPODOC
- EP0243729
- Application
- 87104972
- Application, DOCDB
- 87104972
- Application, EPODOC
- EP19870104972
Titles3
- English
- METHOD AND APPARATUS FOR ELIMINATING APPARENT OFFSET IN THE SERVO CODE IN A MAGNETIC DISC DRIVE
- French
- Méthode et appareil pour éliminer un décalage apparent dans un code d'asservissement dans l'entraînement d'un disque magnétique
- German
- Verfahren und Gerät zum Beseitigen der offensichtlichen Versetzung im Servokode in einem Magnetplattenantrieb
Classification
- CPC, 4
- G11B5/5521
- G11B5/59627
- G11B20/1217
- G11B2020/10916