JPS63166050A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve the productivity and yield of a magneto-optical recording medium preformatted with a means for guiding a laser head and to reduce the cost thereof by preformatting magnetic domain tracks for guiding on a recording film. CONSTITUTION:An enhancement film 2, the recording film 3, a protective film 4 and the magnetic domain tracks 5 for guiding are provided on a substrate 1. The magnetic domain tracks 5 are recorded on the recording film 3 by a magnetical means and are formed to intermittent spiral or concentrical shapes in the circumferential direction at the intervals at which a recording and reproducing head (excitation coil) does not cause off-tracking or said tracks can be continuously formed from the beginning end to the terminal of the recording region. The guiding means (magnetic domain tracks for guiding) are thus formed not by a transfer technique but by the magnetic means and, therefore, generation of defective media is substantially prevented and the productivity and more particularly yield are improved to a greater extent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium on which information can be repeatedly erased and rewritten, similar to a magnetic recording medium.

[Prior art]

2. Description of the Related Art Magneto-optical recording media in which a laser head guiding means is preformatted are conventionally known.

FIGS. 6(a) to 6(1) show the conventionally known manufacturing process of this type of magneto-optical recording medium.

First, as shown in FIG. 6(a), a silane coupling agent layer 32 is formed on the surface of a glass disk 31 that has been polished to a mirror finish and highly cleaned.

Next, as shown in No. 61!1(b), a photoresist 33 is uniformly applied on the silane coupling agent layer 32 to prepare a disk master 34.

Next, as shown in FIG. 6(c), while rotating the disk master 34, the photoresist layer 33 is irradiated with a laser beam 35 modulated by a tracking signal to be recorded.

Next, the exposed disk is subjected to development processing, and the image shown in FIG. 6(d) is
As shown in FIG. 3, guides [36] are formed in the laser beam irradiated portion of the photoresist layer 33 in an array corresponding to the tracking signal.

Next, as shown in FIG. 6(e), conductive nickel 1138 is formed by vacuum deposition, sputtering, etc. on the signal surface of the recorded master disk 37 on which the tracking signal has been recorded in the form of a guide groove as described above. do.

Next, as shown in FIG. 6(f), nickel is electroplated to a thickness of about 0.2 mm using the nickel conductor 1138 as a cathode to form a nickel stump bar 39.

Next, as shown in FIG. 6(g), the nickel conductor f
l! Peel off the interface between l1j38 and photoresist layer 33,
A nickel stamper 39 having a concavo-convex pattern opposite to that of the recorded master 37 is obtained.

Next, the nickel stumper 39 obtained as described above is
After ashing the remaining photoresist and performing necessary machining, the guide grooves 36 are transferred to the transparent substrate 40 using the nickel stumper 39 as a model, as shown in FIG. 6(h).

Furthermore, as shown in FIG. 6(i), on the guide groove forming surface of the transparent substrate 40 to which the guide grooves 36 have been transferred, the apparent Kerr rotation angle is increased to improve the reproduction characteristics. enhancement 1141, magneto-optical recording film 42, and protective film 4
3 are sequentially stacked to form a desired magneto-optical recording medium.

[Problem that the invention seeks to solve]

By the way, tracking of the magneto-optical recording medium reproduced as described above is carried out by directing a laser 45 and an optical circuit from an optical head 44 arranged on the outer surface of the transparent substrate 40 to the guide groove 36, as shown in FIG. The laser beam 47 guided through the recorder 46 is irradiated with the reflected light 47 from the recording [43].
A is detected by a photodetector 49 such as a photodiode divided into four parts, for example, through a cylindrical lens 48. That is, if the beam spot is adjusted so that the output difference of each element of the four-split photodiode 49 is zero when it is on-track to the guide groove 36, when the beam spot is off-track, the beam spot will not be incident on each of the elements. This is because the amount of reflected light changes.

This causes a difference in the output of each element. Therefore, the optical head 44 can be tracked along the guide groove 36 by applying tracking servo so that the output difference between the respective elements becomes zero.

Further, the information recorded in the same uneven form on the transparent substrate 40 is transmitted through a focusing lens 47a by the reflected light 47a from the recording film 43.
This is done by detecting with the photodetector D51 via the photodetector D51.

In this way, the guide groove 36 formed on the transparent substrate 40 is irradiated with the laser beam 47, and the reflected light 4 from the guide groove 36 is
In a magneto-optical distribution medium in which tracking servo is applied by detecting 7a, the tracking accuracy depends on the machining accuracy of the guide groove 36, and the machining accuracy of the guide groove 3G is poor.

Problems such as crosstalk occur, and in the worst case, the optical head goes off track, making it impossible to record or reproduce information.

However, the guide groove 36 transferred to the transparent substrate 40 is
The width is 0.4μm to 0.6μm, and the depth is approximately 0.1μ■
1. It is formed with high accuracy because it is formed by ultra-fine processing with a pitch of about 1.6 μm, it is formed over the entire area of the disk, and it is formed by repeating transfer multiple times. is in trouble. For this reason, the yield of magneto-optical recording media is poor and manufacturing costs are high.

[Means for solving the dizziness point]

The present invention solves the problems of the prior art described above.

A magneto-optical recording medium in which a laser head guide means is preformatted in order to improve productivity and yield as well as reduce manufacturing costs.

This is characterized by preformatting guiding magnetic domain tracks on the recording film. [Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a plan view of a magneto-optical recording medium showing an example of a guiding magnetic domain track, and FIG. 2 is a cross-sectional view schematically showing the film structure of the magneto-optical recording medium, where 1 is a substrate.

2 is an enhancement film, 3 is a recording film, 4 is a Wi-retention film, 5 is a guiding magnetic domain track, and 6 is a recording bit.

The substrate 1 is made of glass, polymethyl methacrylate (
It is made of a transparent material such as PMMA), polycarbonate (PC), or epoxy, and is formed into a disk shape with smooth front and back surfaces.

The enhancement [2] is apparently intended to increase the above Kerr rotation angle, and is formed on one side of the substrate 1 using a dielectric material such as SiN.

The recording film 3 is made of a material such as TbFeCo, GdTbFe, T
bFe-GdTbFe, GdTbFeGe, GdTbC
It is made of any magneto-optical recording material such as O, and is formed on the enhancement film 2.

Tamotsu: f! ! One film 4 is formed on the recording film 3 using a material such as SiN that does not transmit two layers.

The guiding magnetic domain track 5 is recorded on the recording film 3 by magnetic means. The guiding magnetic domain track 5 can be recorded in a spiral shape or in a concentric circle that is intermittent in the circumferential direction with intervals that prevent the recording/reproducing head (excitation coil) from off-tracking, or as shown in FIG. It can also be formed continuously from the start end to the end of the @ area. In the case of continuous magnetic recording in the circumferential direction, when the eccentricity of the substrate 1 is 30 to 100 μm, the interval between the reversing magnetic domains that are in contact with l# can be set to 0, 8 mm to 2, 6 mm. Although it is possible, from the viewpoint of reliability, it is preferable to make it approximately 1 mm.

Recording pit 6 is 1st I3! As shown in I, the information is recorded in the intermediate region between the two guiding magnetic domain tracks 5, 5. Further, when the guiding magnetic domain tracks are formed intermittently, it is also possible to record between the reversal magnetic domains.

The magneto-optical recording medium of the embodiment can track the guiding magnetic domain track 5 by irradiating a laser beam along the guiding magnetic domain track 5 and reading the Kerr rotation angle of the reflected light. This allows information to be recorded, played back,
Erasing and rewriting are performed.

In the magneto-optical recording medium of the above embodiment, the guiding means (guiding magnetic domain tracks) are formed by magnetic means and do not rely on transfer technology, so there is almost no occurrence of defective products, and productivity, especially yield, is significantly improved. be able to. In addition, when the guiding magnetic domain tracks are formed intermittently, 231! Compared to the case where the guiding magnetic domain tracks are formed in succession, the time required to form the guiding magnetic domain tracks is shorter, and this is more practical.

A first example of a method for manufacturing a magneto-optical distribution medium according to the present invention will be described below.

FIG. 3 shows the first part of the manufacturing apparatus for a magneto-optical recording medium according to the present invention.
FIG. 2 is a cross-sectional view showing an example, mainly showing a spindle II, an excitation coil 12, a laser 13, an optical modulator 14,
It consists of an input circuit 15 of the optical variable 111614, a reflecting mirror 16 placed opposite the excitation coil 12, and an objective lens F. In this figure, 18 indicates a magneto-optical v2@ medium mounted on the spindle 11.

When a guide track is magnetically recorded on the recording film of the magneto-optical recording medium 18 using the manufacturing apparatus.

The spindle 11 is rotated to drive the magneto-optical recording medium 18, whose entire surface is magnetized in a certain direction, at a constant angular velocity. Further, the excitation coil 12 is energized to apply a magnetic field in a desired recording direction to the recording film of the magneto-optical recording medium 18 6
Next, the laser 13 is operated and the reflector *16 is rotated, so that the laser beam 19 irradiated from the objective lens 17 is swung at a constant speed from the start end to the end of the marked region of the magneto-optical recording medium 18. Of course, the swing speed of the laser beam 19 is adjusted so that the guiding magnetic domain tracks 5 are continuously formed at a predetermined pitch. As a result, a spiral guiding magnetic domain track 5 is formed in the radial direction of the film.

Next, a second example of the method for manufacturing a magneto-optical recording medium according to the present invention will be described.

FIG. 4 shows a magneto-optical recording medium according to the present invention! FIG. 3 is a sectional view showing a second example of the R-formatting device, in which numeral 21 indicates a mask, and other members and devices that are the same as those shown in FIG. 3 are designated by the same reference numerals.

As shown in FIG. 5, the mask 21 is formed of a rectangular flat plate having a length slightly longer than the radius of the magneto-optical recording material 18, and has the spindle 11 at one end.
A through hole 22 for fitting is provided. Further, a large number of slits 23 are opened at positions corresponding to the recording areas of the magneto-optical recording medium 18 with the through hole 22 at the center, and spaced at intervals equal to a desired track pitch.

When magnetically recording guide tracks on the recording film of the magneto-optical recording medium 17 using the manufacturing apparatus, the spindle 11 is rotated and the excitation coil 12 is rotated as in the first example.
energizes and further activates the laser 13. In this state, a drive signal is input to the optical modulator 14 from the input circuit @tS, and the reflecting mirror 16 is rotated to direct the laser beam 19 irradiated from the objective lens 17 onto the magneto-optical recording medium. The recording film is irradiated through the slit 23 of the mask 21 while being swung in the radial direction of the mask 21 .

As a result, short inverted magnetic domains corresponding to the track pitch are formed in the radial direction of the recording film. By performing this continuously in the circumferential direction of the magneto-optical recording medium, it is possible to form concentric guiding magnetic domain tracks 5 that are discontinuous in one circumferential direction.

The gist of the present invention is that guiding magnetic domain tracks are magnetically recorded on a magneto-optical film.

The means for forming the guiding magnetic domain tracks are not limited to those shown in the first and second examples.

For example, a plurality of reflecting mirrors and optical heads may be arranged in the radial direction of the magneto-optical recording medium 18, and each optical head may record a small portion of the recording area. In this case, the amplitude of each reflected light beam can be reduced, so that the formation speed of the public guiding magnetic domain track can be improved.

In addition, by producing a magnetic stamper having the same magnetic track as the desired guiding magnetic domain track and pressing the magneto-optical recording medium against the magnetic stamper, the guiding magnetic domain track can be transferred to the magneto-optical recording medium. It is also possible to use the following means.

Further, in the above-mentioned embodiments, a single magneto-optical recording medium was explained, but the gist of the present invention is not limited to one that is used in this state.

For example, by bonding two of the above-mentioned units with the recording film inside,
It can be applied to a magneto-optical recording medium of any structure, such as a double-sided recording type magneto-optical distribution medium.

〔Effect of the invention〕

As explained above, in the magneto-optical recording medium of the present invention, the guide means is formed by magnetic means and does not rely on transfer technology, so there is almost no occurrence of defective products and productivity, especially yield, is significantly improved. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a magneto-optical recording medium according to the present invention. FIG. 2 is a sectional view of a magneto-optical recording medium according to the present invention. FIG. 3 is a sectional view showing a first example of a magneto-optical recording medium manufacturing apparatus, FIG. 4 is a sectional view showing a second example of a magneto-optical recording medium manufacturing apparatus, and 5vR is a sectional view showing a second example of a magneto-optical recording medium manufacturing apparatus. A perspective view of a mask applied to the device, FIGS. 6 (8) to (1) are process explanatory diagrams showing the manufacturing process of a conventionally known magneto-optical recording medium, and FIG. 7 is a conventionally known optical method. FIG. 3 is a circuit diagram showing a track servo system. 1... Board, 2... Enhancement meditation, 3
...recording film, 4...ho 1IIIl[,
5...Magnetic domain track for guidance. 6... Recording pit, 11... Spindle, 12... Excitation coil, 13... Laser, 14... Optical modulator, 15 ...Input circuit, 16...Reflector, 17...Objective lens, 18...Magneto-optical recording medium, 19...
・・・Laser beam, 21...Mask 1 Figure 1: Substrate 5 "f internal 3rd section 7 5a:/fil can 1 6:1 @c", yt- Figure 2 Figure 3, Figure 4] 2 Figure 5 (a) 1st floor

Claims (1)

[Claims] 1. A magneto-optical recording medium in which guiding means for a laser head is preformatted, characterized in that a magnetic domain track for guiding is preformatted on a recording film.