Magnetic pattern forming method, magnetic pattern forming apparatus, magnetic disk, and magnetic recording apparatus

Abstract

A magnetic pattern forming apparatus, which is designed to form a desired magnetic pattern on a magnetic disk having a magnetic layer on a substrate, is made up of a mask having a pattern identical or similar to the desired magnetic pattern, a projection optical system for exposing the magnetic disk to a spot-like energy beam coming through the mask to heat the magnetic layer for projecting the mask pattern to the magnetic disk at a one-to-one ratio or a predetermined reduction ratio, a magnetic field applying device for applying an external magnetic field to the magnetic disk, a control unit for conducting scanning with the spot-like energy beam with respect to the magnetic disk and the mask in their radial directions while rotating the magnetic disk and the mask.

Description

BACKGROUND OF THE INVENTION [0001] (1) Field of the Invention [0002] The present invention relates to a magnetic pattern forming method and apparatus for use in a magnetic recording apparatus (magnetic disk), and more particularly to a magnetic pattern forming method and apparatus, magnetic disk and magnetic recording apparatus suitable for recording / reproduction (readout) by a flying / contact head. [0003] (2) Description of the Related Art [0004] Magnetic recording apparatus represented by a magnetic disk unit (hard disk drive) have come into widespread use as an external storage of information processing equipment such as computers, and in the recent years, they are being used as a moving-picture recording apparatus or a recording apparatus for a set-top box. [0005] The magnetic disk unit (hard disk drive) is usually made up of a shaft for fixing one magnetic disk or a plurality of magnetic disks in a skewering manner, a motor for turning the magnetic disk joined through a bearing ...

AI Technical Summary

Benefits of technology

[0029] The present invention has been developed with a view to eliminating the above-mentioned problems, and it is therefore an object of the invention to provide a magnetic pattern forming method and apparatus pertaining to a technique of forming a magnetic pattern on a magnetic recording medium by means of a combination of local heating and exposure to an external magnetic field, and capable of efficiently forming a minute magnetic pattern with higher precision, and in its turn offer a higher-density magnetic disk and magnetic recording apparatus in a small amount of time and at a low cost.

Problems solved by technology

However, since the center of gravity of the positioning mechanism and the center of gravity of the actuator exist at different positions, difficulty is encountered in executing track position control with high accuracy and recording a servo signal with a high precision.

There are problems which arises with this technique, however, in that an unstable state of a flying head due to the irregularities exerts adverse influence on recording / reproduction, cost rises because there is a need to use a high-power laser beam for the formation of the irregularities, and the one-by-one formation of the irregularities is time-consuming.

Thus, although the above-mentioned technique is relatively applicable to a flexible floppy disk easy to press or a low-corecivity magnetic disk which does not require too great contact, considerable difficulty is experienced in applying it to a high-density recording magnetic disk using a hard substrate, whose corecivity exceeds 3000 Oe.

That is, in the case of the magnetic disk using a hard substrate, there is a possibility that microscopic dirt particles or the like get between the master disk and the medium at the contact to produce defects on the medium or damage the high-priced master disk.

In particular, for a glass substrate, the contact therebetween does not reach satisfaction because the dirt particles get therebetween, which makes the magnetic print impossible or causes cracks on the magnetic recording medium.

Furthermore, with the technique disclosed in U.S. Pat. No. 3,869,711, although a pattern formed obliquely with respect to a track direction of a disk is recordable, the recording is limited to the formation of only a pattern with a low signal strength.

However, in the case of the oblique pattern, a magnetic field for the reverse magnetization becomes perpendicular to a gap defined by the ferromagnetic layer of the master disk, which makes it difficult to tilt the magnetization in a desired direction.

In consequence, a part of the magnetic field escapes to the ferromagnetic layer to make it difficult to expose a desired portion to a sufficient magnetic field at magnetic print so that a sufficient reverse magnetization pattern is difficult to form and a high signal strength is hard to obtain.

Moreover, since the area subjected to recording is limited to the heating area while the recording in other than the heating area cannot be made even if a magnetic field is brought to strike thereon, the recording of a clear magnetic pattern is possible without bringing a mask or the like into contact with the medium.

If the magnetic pattern is made more minute up to 1 to 2 μm or formed in terms of submicron, because of the limit to the processing accuracy, difficulty can be encountered in patterning a mask with high precision, and the alignment precision between the mask and the medium can deteriorate so that a magnetic pattern cannot be formed with sufficiently high accuracy.

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