Head and disk tester with a thermal drift-compensated closed-loop positioning system
US6023145A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 21, 1999 |
| Grant date | Feb 8, 2000 |
| Priority date | — |
| Expiry date | Apr 21, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/596
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The head/disk tester of the invention has a housing 43 that houses spindle 44 that rotatingly supports a magnetic disk 31. The housing supports a moveable carriage 30 that, in turn, supports a magnetic head 32. Positioning means 39 and 41 are used to move the carriage and the magnetic head across the magnetic disk. These positioning means include stepper motors that realize coarse positioning of the magnetic head, and a piezo actuator 37 that is used for fine positioning. Linear encoders 40 and 42 located at both sides of the carriage provide feedback information to a closed-loop positioning system that controls the piezo actuator. A set of special signals ("servo bursts") pre-written at a given track of the magnetic disk is used as an additional source of feedback information for the same closed-loop positioning system. This positioning system includes a servo analyzer 45 that reads and processes servo burst signals from the magnetic disk, and a position controller 49 that controls the piezo actuator. The controller contains two control loops: a proportional-integral-derivative (PID) loop and an additional servo burst loop. During any movement of the magnetic head to a prescribed …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.