Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
1999-03-23
2001-06-12
Tupper, Robert S. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06246549
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to media drives, such as tape drives that read and write data on a magnetic tape in more than one band, and in particular to the use of a servo controlled read/write head actuator for moving the read/write heads from band to band as well as for track following within each band to precisely align the read heads with the tracks of data that are written in a selected band on the magnetic tape.
Problem
It is a problem in the field of tape drives that read and write data on a magnetic tape in more than one band to have the write heads record adjacent tracks of data without overlapping and have the read heads accurately follow the previously written data tracks that are recorded on the magnetic tape. As the track density becomes higher, a track following servo is required to both keep the write heads from wandering into and writing over adjacent tracks and to keep the read tracks aligned to the written tracks on play back. In high performance tape drives with data written in more than one band, the servo controlled read/write head actuator is used for moving the read/write heads from band to band as well as for track following within each band. This arrangement requires a read/write head actuator that has a long stroke for moving the read/write heads between bands as well as high resolution and high bandwidth for precise track following within a selected band of tracks. These combined requirements result in a relatively massive read/write head carriage and a high performance read/write head actuator. In addition, as the read/write head is forced to follow servo tracks written on the tape, the reaction forces that are generated by this action are taken up by the base of the drive. These reaction forces can cause minute movements in the base of the drive, which movements can couple back to and cause motion in the tape cartridge in which the magnetic tape is housed. The motion of the tape cartridge impacts the operation of the track following servo loop in that the effects of the motion appear as broad band noise in the servo loop, which tends to excite any resonance or instability in the servo loop.
An example of a typical tape drive head adjustment apparatus is disclosed in U.S. Pat. No. 5,414,578 wherein a voice coil servo motor is provided for adjusting a magnetic tape head. This apparatus comprises a head positioning assembly that has a magnet housing and fixed suspension vertically positionable by a worm gear/screw shaft arrangement and is further positional for fine tuning by a magnet mounted within the magnet housing and an electrical coil surrounding the magnet and attached to a head mount structure holding the magnetic head. The head mount structure is fine-tuned, vertically positional with respect to the magnet housing by magnetic force on the coil induced by select and varying electrical current through the coil.
However, there are no systems that address the problem of servo noise induced by the read/write head actuator operation. More specifically, as the read/write head is forced to follow servo tracks written on the tape, reaction forces that are generated by this action are taken up by the base of the drive and coupled back to and cause motion in the tape cartridge.
Solution
The above described problems are solved and a technical advance achieved by the present method and apparatus for reducing the coupling of the reaction force from the read/write head actuator into the track follow servo loop of a media drive, termed “reaction force decoupling system” herein. This is accomplished in a tape drive by reducing the motion that is coupled back into the tape cartridge from the reaction force that is generated by the operation of the read/write head actuator. The read/write head actuator consists of a magnet assembly which produces a large magnetic field in an annular gap and a coil of wire which operates freely in the magnetic field of the gap. The magnet assembly is mounted to the base of the drive and the coil is attached to the read/write head carriage. When current is applied to the coil, a force is produced between the coil and the magnet assembly to move the read/write head carriage. The magnet assembly is disconnected from the base of the drive and mounted on dual flexures arranged in a four bar linkage parallel guide arrangement. The reaction forces that are generated by the operation of the read/write head actuator must deflect the flexures to apply a load to the base of the drive. As the flexures are deflected, the magnet assembly is also guided to remain coaxial with the coil. At low frequencies, the same reaction force is still applied to the base of the drive through this apparatus but above the resonant frequency of this apparatus, the reaction forces are attenuated with the result that the servo loop instability is reduced.
REFERENCES:
patent: 5416658 (1995-05-01), Sega et al.
patent: 59-054077 (1984-03-01), None
patent: 59-210577 (1984-11-01), None
patent: 06-267206 (1994-09-01), None
Goodknight Frank
Janssen Donovan Milo
Todd Christian Allen
Yeakley Lester Marvin
Duft, Graziano & Forest
Storage Technology Corporation
Tupper Robert S.
LandOfFree
Method and apparatus for reducing the coupling of the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for reducing the coupling of the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for reducing the coupling of the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2453406