JP2003217117A - Inspecting method for magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assure high quality of a magnetic recording medium wherein a magnetization pattern in accordance with prescribed information is formed by magnetic transfer. <P>SOLUTION: The existence of contamination having ≥30 pieces/cm<SP>2</SP>high density and having ≥0.3 μm diameter or dimple having ≥1 piece/cm<SP>2</SP>high density and having ≥0.3 μm diameter on the surface of the magnetic recording medium 10 wherein magnetic transfer have been performed is detected by an optical surface inspecting instrument. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a magnetic recording medium, and more particularly to a method for inspecting a magnetic recording medium on which information has been transferred by magnetic transfer. It is. 2. Description of the Related Art In general, in a magnetic recording medium, as the amount of information increases, a large capacity for recording a large amount of information, a low cost, and preferably a required portion can be read out in a short time. A medium capable of high-speed access is desired. As an example of this, a high-density magnetic recording medium such as ZIP (Iomega Corporation) composed of a hard disk and a flexible disk is known. In these high-density magnetic recording media, the information recording area is composed of narrow tracks, and a high S / W is obtained by accurately scanning a narrow track width with a magnetic head.
In order to reproduce a signal with N, a so-called tracking servo technique plays a major role. Servo signals for track positioning,
Servo information such as the track address signal and playback clock signal must be recorded in advance on the magnetic recording medium as a preformat when the magnetic recording medium is manufactured. Currently, a dedicated servo recording device (servo track writer) is used. Preformatting has been done. The preformatting by the conventional servo recording apparatus needs to be recorded by the magnetic head one by one on the magnetic recording medium, so that it takes a considerable time and there is a problem in terms of production efficiency. On the other hand, as a method for performing preformatting accurately and efficiently, a method of transferring a pattern carrying servo information formed on a master carrier to a magnetic recording medium by magnetic transfer is disclosed in Japanese Patent Application Laid-Open No. 63-183623. ,
Japanese Patent Laid-Open Nos. 10-40544 and 10-2695
No. 66 is proposed. Magnetic transfer is performed by applying a transfer magnetic field to a master carrier in a state where a master carrier carrying transfer information and a magnetic recording medium as a slave medium receiving the transfer are in close contact with each other by a fine uneven pattern of a magnetic material. Transfers and records the magnetization pattern corresponding to the carried information (for example, servo signal) on the slave medium, and can record statically without changing the relative position of the master carrier and slave medium. Pre-format recording is possible, and the time required for recording is extremely short. However, when magnetic transfer is performed by the above magnetic transfer method, contamination with the magnetic recording medium as a slave medium, generation of dimples, etc. may occur due to contact with the master carrier. There is. If contamination or dimples are present on the surface of the magnetic recording medium, there are problems such as a missing signal in the reproduced servo signal and medium scraping when performing long-time head loading. Therefore, it is desirable that such a problematic magnetic recording medium be detected after magnetic transfer and before shipment. Conventionally, surface inspection of a magnetic recording medium has been performed by loading using a magnetic head, and is performed to determine whether or not it is worth performing servo writing before pre-formatting by servo writing. Yes. It is conceivable to use such a surface inspection with a magnetic head for surface inspection of a magnetic recording medium after magnetic transfer. However, with a surface inspection with a magnetic head, it is difficult to confirm contamination in an attached state. there were. In addition, changes in the reproduction signal are not reflected in the submicron level dimples, and it is difficult to sufficiently evaluate the medium surface level. On the other hand, it is considered that surface inspection using an optical surface inspection machine conventionally used for hard disk surface inspection is effective in analyzing contamination and dimples caused by contact confirmed by magnetic transfer. The present applicant inspects the surface of the magnetic disk using an optical surface inspection machine, and evaluates the transfer signal of the slave medium using the electromagnetic conversion characteristic measuring device (SS-60 manufactured by Kyodo Electronics) for the magnetic disk subjected to the inspection. And the allowable level of the size and density of contamination or dimples on the magnetic disk after magnetic transfer was examined. The present invention has been made in view of the above circumstances, and inspects a magnetic recording medium for assuring high quality for a magnetic recording medium on which a magnetic pattern corresponding to predetermined information is formed by magnetic transfer. It is intended to provide a method. According to the method for inspecting a magnetic recording medium of the present invention, a transfer magnetic field is applied in a state in which a magnetic carrier having a pattern according to information faces a master carrier on the surface. By doing so, a method for inspecting a magnetic recording medium on which the information is magnetically recorded, which is 30 / cm on the surface of the magnetic recording medium using an optical surface inspection machine.
It is characterized in detecting the presence or absence of dimples on the contamination or high density 0.3μm diameter or less than 1 / cm ² or over dense 0.3μm diameter or less than ^2. Here, “more than 0.3 μm diameter” is defined by the size of the maximum diameter of contamination or dimples. As a magnetic recording medium after magnetic transfer, 0.3
Contamination of μm diameter or more is 30 pieces / cm ² or less, or 1 dimple of 0.3 μm diameter or more is 1
The applicant's examination revealed that it is desirable that the number of particles / cm ² or less. Therefore, in the method for inspecting a magnetic recording medium of the present invention, it is detected whether the contamination or dimples having a diameter of 0.3 μm or more exist more than the specified value density or less than the specified value density. According to the magnetic recording medium inspection method of the present invention, the magnetic recording medium on which the magnetic transfer has been performed is performed on the surface of the magnetic recording medium using an optical surface inspection machine.
and detects the presence or absence of dimples density 0.3 [mu] m larger than the diameter than the contamination or 1 / cm ² on the dense 0.3 [mu] m diameter or less than cm ^2, 0.3 [mu] m or more contamination 30 / cm ² or less, Alternatively, it is possible to provide a magnetic recording medium having a good quality in which the dimple having a diameter of 0.3 μm or more is 1 piece / cm ² or less, the reproduction signal failure rate is low, and the medium is hardly scraped even when the head loading is performed for a long time. Can do. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of an optical surface inspection machine, and a specific inspection method for the surface of a magnetic recording medium will be described. Here, the magnetic recording medium 10 to be surface-inspected.
Is a magnetic disk such as a hard disk or a flexible disk, which has been preformatted with a servo signal transferred by magnetic transfer. Magnetic transfer has a magnetic recording medium in which a magnetic recording medium is preliminarily magnetized in advance in a track direction or a vertical direction, and unevenness in a pattern according to information to be transferred to the surface (here, a servo signal). A magnetic pattern corresponding to the transfer information of the master carrier is applied to the slave medium by bringing the master carrier into close contact and applying a magnetic field for transfer substantially opposite to the initial magnetization by a magnetic field application device such as an electromagnet device in this close contact state. It is for transfer recording. The surface inspection is performed as follows. The laser beam L emitted from the laser oscillator 1 is reflected by the dichroic mirror 2, converged by the beam focusing lens 3, and passes through the hole 4 a of the perforated mirror 4 and the hole 5 a of the perforated lens 5. The diameters of the central holes 4a and 5a provided in the perforated mirror 4 and the perforated lens 5 are configured to be larger than the beam diameter, and these holes 4a and 5a are light beams of the light projecting optical system. Since it is provided substantially concentrically with the axis, the laser light L passes through the holes 4a and 5a without being affected by the action of the mirror 4 and the lens 5. Laser light L that has passed through the hole 5a of the lens 5
Is reflected toward the point A on the magnetic disk 10 by the beam irradiation mirror 6. Of the light reflected at the point A, the specular reflection component travels back along the light projecting optical path, and returns to the laser oscillator 1 through the hole lens 5 and the center holes 4a and 5a of the hole mirror 4 again. On the other hand, of the light reflected at the point A, the scattering component indicated by the broken-line arrow in the figure is reflected and diffused by the mirror 6 and is incident on and converged on the portion other than the central hole 5a of the perforated lens 5. The The scattered light converged by the perforated lens 5 is incident on a portion other than the central hole 4 a of the perforated mirror 4. Since the perforated mirror 4 is disposed at an angle of 45 ° with respect to the optical axis of the light projecting optical system, the scattered light is reflected in a direction substantially perpendicular to the incident direction. The light is converged on the light receiving surface of the light receiving element 7. By moving the laser beam irradiation position in the radial direction of the magnetic disk and rotating the magnetic disk 10, the entire surface of the magnetic disk is inspected by scanning the laser beam. As described above, the entire surface of the magnetic disk is inspected by the optical surface inspection machine, and the presence or absence of contamination with a diameter of 0.3 μm or more, higher than 30 / cm ² , or from 1 / cm ² . The presence or absence of high-density dimples having a diameter of 0.3 μm or more is detected. As a result of this inspection, contamination with a diameter of 0.3 μm or more is 30 pieces / cm ² or more, or 0.3
If a dimple having a diameter of μm or more is detected as having no dimple / cm ² or more, it is judged as a good magnetic disk. On the other hand, a magnetic disk that is detected as having contamination or dimples greater than a specified value is subjected to a treatment such as performing an inspection again after being cleaned, or disposing of it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view for explaining a magnetic recording medium inspection method using an optical surface inspection machine. DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Dichroic mirror 3 Converging lens 4 Perforated mirror 5 Perforated lens 6 Beam irradiation mirror 7 Light receiving element 10 Magnetic disk (magnetic recording medium)

Claims (1)

What is claimed is: 1. A magnetic field for transfer is applied in a state of facing a master carrier having a patterned magnetic layer on the surface according to information, thereby recording the information magnetically. A method for inspecting a magnetic recording medium, comprising: using an optical surface inspection machine, contamination on the surface of the magnetic recording medium at a density higher than 30 / cm ^{2 and} having a diameter of 0.3 μm or more, or 1 / A method for inspecting a magnetic recording medium, comprising detecting the presence or absence of dimples having a diameter of 0.3 μm or more of cm ² or more.