Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse...
Reexamination Certificate
1999-12-16
2001-11-06
Dinh, Tan (Department: 2651)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Reexamination Certificate
active
06314062
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to magneto-optical disk apparatuses, and more particularly, to a magneto-optical disk apparatus that can adjust the position of the magnetic head with respect to the optical head.
2. Description of the Background Art
Attention is focused on a magneto-optical recording medium as a rewritable recording medium of great storage capacity and high reliability. The magneto-optical recording media are now applied as computer memories and the like. Standardization of a magneto-optical recording medium having a storage capacity of 6.0 Gbytes (AS-MO (Advanced Storage Magneto-optical Disk) standard) is in progress to be provided for actual usage. This magneto-optical recording medium of high density has the signal reproduced by the MSR (Magnetically Induced Super Resolution) method. More specifically, a laser beam is projected to transfer the magnetic domain of the recording layer of the magneto-optical recording medium to a reproduction layer and also forming a detection window in the reproduction layer to allow detection of only the transferred magnetic domain. The transferred magnetic domain is detected from the formed detection window.
Also, a magnetic domain enlargement reproduction technology has been developed. An alternating magnetic field is applied in reproducing a signal from a magneto-optical recording medium. The magnetic domain of the recording layer is enlarged to the reproduction layer by the laser beam and the alternating magnetic field while transferring to reproduce a signal. A magneto-optical recording medium that can record or reproduce signals of 14 Gbytes by virtue of this technology has been proposed.
It is expected that signals will be recorded or reproduced at further higher density, in which case the frequency of the alternating magnetic field is increased. It is therefore necessary to reduce the diameter of the coil that generates the magnetic field to approximately 20 &mgr;m from the current diameter of approximately 200 &mgr;m. In the case where the diameter of the coil is approximately 200 &mgr;m, which is sufficiently greater than the diameter of the beam spot, it was only required to have the magnetic head roughly follow the optical head. However, in the case where the diameter of the coil becomes as small as approximately 20 &mgr;m, any slight deviation of the center of the magnetic field from the center of the laser beam will impede proper recording or reproduction of signals.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a magneto-optical disk apparatus capable of correct recording and/or reproduction of signals.
Another object of the present invention to provide a magneto-optical disk apparatus that can set the position of the magnetic head in coincidence with the position of the optical head.
According to an aspect of the present invention, a magneto-optical disk apparatus includes an optical head and a magnetic head. The optical head is provided to face a magneto-optical disk. The magnetic head applies a first magnetic field and a second magnetic field of a direction opposite to that of the first magnetic field within a beam spot formed on a magneto-optical disk by a laser beam directed from the optical head towards the magneto-optical disk.
Preferably, the magnetic head includes a first magnetic element and a second magnetic element. The first magnetic element generates a first magnetic field. The second magnetic element is provided apart from the first magnetic element, and generates a second magnetic field.
Preferably, the magneto-optical disk apparatus further includes a position adjustment unit that adjusts the position of the magnetic head in response to a magneto-optical signal output from the optical head.
Further preferably, the position adjustment unit includes a position adjustment circuit and a position adjustment mechanism. The position adjustment circuit generates a drive signal to adjust the position of the magnetic head in response to a magneto-optical signal output from the optical head. The position adjustment mechanism responds to the drive signal from the position adjustment circuit to move the magnetic head in the radial direction of the magneto-optical disk and/or in the direction of the tangent of the track of the magneto-optical disk.
The main advantage of the present invention is that correct signal recording or reproduction is allowed because two magnetic fields in opposite directions are applied in the beam spot to eliminate deviation in the position of the magnetic head with respect to the optical head according to a magneto-optical signal output from the optical head.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5193080 (1993-03-01), Mohri et al.
patent: 5367508 (1994-11-01), Haba
patent: 5471439 (1995-11-01), Katayama et al.
patent: 5485435 (1996-01-01), Matsuda et al.
patent: 6185162 (2001-02-01), Kunimatsu et al.
Suzuki Yoshihisa
Tanaka Sayoko
Armstrong Westerman Hattori McLeland & Naughton LLP
Dinh Tan
Sanyo Electric Co,. Ltd.
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