JPS5936346A - Recording carrier - Google Patents

Abstract

PURPOSE:To prevent deformations of a substrate due to elevated temp. of a recording film at the time of recording and eliminating and to improve the thermal conductivity upon the formation of the recording film, by providing a stable inorg. interlayer under the specified temp. and forming the photorecording thin film on it. CONSTITUTION:As a photodisc substrate 1, a plastic substrate composed of polymethacrylates or the like is used and an inorg. interlayer consisting of SiO2, SiO, Al or the like, being stable at <=500 deg.C, and having 100-1,000Angstrom thickness is formed on the substrate 1. A photomagnetic thin film 3 of an amorphous alloy consisting of one or more among Gd, Td and Dy whose Curie point or the working temp. at the recording time is >=90 deg.C and the balance Fe, or one among Ge, Sn and Bi in addition to these elements is formed on the interlayer 2 by sputter- vapor depositing. The disc having track-guide grooves being capable of fitting grooves similarly at any case of recordation, regeneration and elimination, producing no deformation due to heat, and hence making no noise due to the deformation is obtd.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is suitable for recording, reproducing, and erasing information by irradiating a light beam onto a magneto-optical recording thin film provided on an information record carrier, especially a plastic substrate. It concerns record carriers.

Conventional structure and its problems Commonly used optical disks are reproduced by converting the unevenness formed on a substrate into signal strength by interference of light, and the reflectance by the presence or absence of a thin film. believe in the difference between
There is a method to convert the strength of These recording phases are achieved by changing the shape of the surface of the recording medium during recording, but the user's use is limited to playback, so the servo mechanism for the tracking method is also a three-bit system. Methods have been devised to obtain error signals from recorded information and footbank them, such as the system system and the ring system.

However, these tracking methods require track guide grooves to be provided on the disc, since mechanical precision is not sufficient for track alignment during recording for record/play discs (hereinafter referred to as DRAW discs) that have the function of being recorded by the user. A method has been devised to obtain an error signal for trunk alignment during recording and playback from the guide groove. At this time, it is safe to use a board with a trunk guide groove, but due to manufacturing technology constraints, it is preferable that the track guide groove be molded from plastic. It is easy to imagine that it could be used in a magneto-optical disk with high performance. However, in reality, it is difficult to realize a magneto-optical disk provided with rank guide grooves. One of the reasons for this is that when recording information in a magneto-optical memory is generated by irradiating a light beam from the substrate side, it is necessary to detect a minute rotation angle of the polarization plane, so the plastic 4'A that makes up the guide groove is separated. As such, only polymethyl methacrylate (hereinafter referred to as PMM) with a small birefringence can be applied. On the other hand, PMMA melts at about 130'C, whereas when recording and erasing on a magneto-optical recording film, the film surface temperature is kept at 150-300°C.
It is safe to keep the temperature around 0℃. Therefore, during recording F and erasing, the PMMA forming the guide groove undergoes a thermal shape change. If this -1 inch is repeatedly recorded, erased, and played back,
The change in shape causes noise, and as a result, track alignment becomes unstable, which is extremely inconvenient for a magneto-optical disk that can be erased. Another reason why magneto-optical disks with i-rack guide grooves have not been realized d2
Sputtering deposition is used to form many magneto-optical thin films, but plastic substrates have extremely poor thermal conductivity and electrical conductivity, resulting in high temperatures and charge-up phenomena at the extreme surface of the substrate, making it difficult to use under vacuum. Due to outgassing, it has been difficult to obtain a magneto-optical thin film with desired properties.

For these reasons, magneto-optical disks are currently
: 1.11, When recording, the servo for track alignment was not installed and the track servo was used for the track servo from the information recorded only during IIJ production. The error signal is limited to 1, and it has not been possible to provide a magneto-optical disk that can be repeatedly recorded, reproduced, and erased.

The first object of the present invention is to realize a magneto-optical disk having a track guide groove by forming a magneto-optical thin film on a substrate whose surface is made of plastic, thereby realizing recording and recording. P
) An object of the present invention is to provide a magneto-optical recording medium which enables similar track alignment in both recording and erasing.

Structure of the Invention The record carrier of the present invention has a plastic base (50Q
An inorganic intermediate layer is formed which is stable at temperatures above .degree. C., and a recording thin film is formed thereon. Due to this /<-, when recording/erasing is performed using light beam heating, the temperature of the recording film is -! 1) It is possible to prevent the shape of the substrate from changing, and it is also possible to improve the heat conduction of the extreme surface when forming a thin film by sputter deposition. A magnetic f1 film having J properties can be easily produced (i). In particular, when recording by light beam heating, the recording operating temperature is 150~
Even at 200'C, the beam can be irradiated.
Temperature exceeds 3o○℃ at the end to prevent deformation during recording/ξ
Therefore, it is desirable that the interlayer particles be stable at temperatures of 600° C. or higher.

Due to constraints on the storage film of the shredded record carrier, it is desirable to irradiate the light beam from the substrate surface.Especially in magneto-optical recording, groove formation is required because the birefringence must be small. PMM as a plastic material for
A (refractive index 1.49) L is not suitable for practical use. Silicon oxide is desirable as the intermediate layer, and among silicon oxides, Si02 (refractive index 1.45) has a refractive index close to that of PMMA.
It is desirable to use This is because if there is a large refractive index difference between the substrate and the silicon oxide layer, the influence of reflection at the interface between the two layers not only reduces the input power to the magnetic thin film during recording, but also reduces the apparent power that determines the reproduction characteristics. This is because the magnetic Kerr rotation angle decreases.

The thickness of SiO2 is preferably 1,008 or more, more preferably 1,008 to 1,000.

The reason for this is that when a magnetic thin film is formed directly on PMMA soil, substrate damage occurs at the same time as thermomagnetic recording is performed on the magnetic film, whereas when SiO2 of 100% or more is provided between the plastic substrate and the magnetic film. This is because, even if twice the recording critical energy is applied, substrate distortion does not occur. On the contrary, as shown in FIG. 2, the recording critical energy decreases when the thickness of S s 02 is 1000 mm or less, which has the advantage of significantly improving recording sensitivity.

This tendency was the same even when SiO and Aλ having different refractive indexes were used.

DESCRIPTION OF EXAMPLES Hereinafter, examples of the present invention will be described in detail.
] By press-molding PMMA, as shown in FIG.

On a substrate 1 having a diameter of 120mm and provided with a track guide groove 5 having a track depth of 700mm, 100 Si02 films 2 were deposited by electron beam evaporation. Furthermore, after that, (Gdo12TbO, 12FeO
,76) 0.95 GeO,05 recording layer 3 was formed by 400 people. As a result, a disk with a magnetic Kerr rotation angle of 0.4 degrees could be manufactured.

This disk was irradiated with light from the substrate side, and recording was performed with a light beam spot diameter of 1.2 μm, disk rotation speed of 1100 Orp + recording frequency of I MHz, and recording bias magnetic field of 2000 e. As a result, the recording pattern was not formed when the disk input power was 2.2 mW or more. This was confirmed, and no change in the shape of the substrate was observed even when 6 mW was applied. 5102 layer is not provided, PMM
In the case where the Gd Tb Fe Ge film is directly sputter deposited on the A substrate, the Kerr rotation angle is . If you record under similar conditions, you can only get 2.5m.
With W, a shape change was observed in a part of the substrate at the same time as recording, and this example was more than twice as effective in terms of substrate damage during recording.

[Example 2] Using a substrate similar to that described in Example 1, a disk similar to that of Example 1 was manufactured except for Kokichi, in which 300 Sio2 films were formed by electron beam evaporation.As a result, the Kerr rotation angle o , obtained a 4 degree magneto-optical disk.

Further, as a result of recording under the same conditions as in Example 1, it was possible to record 7 mW with disc insertion puff-2, and 6.
No change in the shape of the substrate was observed even when mW was applied.

[Example 3:] A disk similar to that of Example 1 was prepared except that the film thickness of S x O2 was set to 1000, and the same recording was performed.As a result, recording was performed with a disk input power of 4 mW or more. Even when 8 mW was applied, no change in the shape of the substrate was observed.

[Example 4] The Si02 film was replaced with a SiO film. A disk similar to that shown in Example 2 was manufactured except for this point. As a result, a magneto-optical disk with a magnetic Kerr rotation angle of 0.35 degrees was produced. knee
Furthermore, as a result of recording under the same conditions, 11 fruits were obtained with the same ruled results as in 2.

[Example 5] A9. A disk similar to that shown in Example 2 was prepared except that the magneto-optical layer was replaced with a film and that Gdo, 12TbO012Feo, and 76 mm were used.

As a result of performing the same recording as in Example 1 except that the light beam was incident from the thin film side using this disk, 3
, the recorded pattern was confirmed at 6 mW or more, and no change in the shape of the substrate was observed at 6 mW.

As described in the embodiments above, the intermediate layer 2 is A Q r S
t02.

Since similar effects can be obtained regardless of SiC, S
SiOx consisting of a mixture of iC2I810 (1<, ×
2) Odor-C is also effective, especially when the film thickness is 100 to 1
If the incident direction is on the recording film side, the intermediate layer 2 is stable at 600'C or higher. A thin metal film is also effective. In this interaction, the optical beam enters from the board side, r1 and 'Jv', and 4) J' of the track guide full formation part.
7'j i, J, Jolt 4jF Since it is not affected by F, you can choose a glass material that is stable at high temperatures without being limited to PMMA. The peace of mind of choosing a plastic that is stable at high temperatures for the Samurai is gone.
As shown in FIG. 3, a plastic substrate is used in the 1st embodiment and C is a substrate coated with glass on the 2nd side of the glass substrate 4. The material of the substrate can be freely selected. The method of using is also self-effective.

- In the example, a plastic substrate with track guide grooves was used, but in addition to the track guide grooves, for example, positioning/column address numbers, music signals such as BGM, accompaniment, and backing chorus etc. Alternatively, it is also effective to use a substrate on which five recordings such as ``Delivery'' and ``Speech'' in language kidnappings are formed with unevenness and -1 knee).

1. In the examples, as a magneto-optical recording film ("dO, 12
TbO, 12”80.76 ) 0,95 Geo, o5
2 used/ζ is the li of the plastic substrate during recording.
t11. ．． Effect 1↓ of 5 is all optomagnetic +
4 #:'l, 1.・It is not only possible to use light, but also to utilize the change of state between amorphous and crystalline materials, such as light and memory.
3. The effects of the invention are summarized in 1-1. 1. According to the present invention, when recording and When erasing with the same input power, you can prevent thermal scratches on the PMMA substrate, and as a result, it is always stable even after repeated recording, IIJ, and erasure (7). Track servo can be realized.It is possible to increase heat conduction on the surface of the substrate during recording film production, so it is effective in preventing chi- This has the advantage that a magnetic film having desired characteristics can be easily obtained.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an embodiment of a record carrier according to the present invention, and Fig. 2 shows the relationship between the thickness of S IO2 and the energy required for recording. The figure shown in FIG. 3 is a sectional view showing another embodiment of the recording body 411 according to the present invention. 1... Substrate, 2... Intermediate layer, 3... Recording film, 4 Glass substrate. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 87θ2 Enoki thickness (/4'2

Claims (1)

[Scope of Claims] (1) Recording, reproduction and erasing are performed by irradiation with an optical vino. Recording carrier 1, (2) characterized in that an intermediate layer made of an inorganic material that is stable at 500° C. or lower is provided between the recording thin film and the substrate.
Information recording carrier 3 according to item 1, (3) characterized in that the intermediate layer is made of silicon oxide or SiO2. (4) Claims 1 and 2, characterized in that the thickness of the intermediate layer is less than or equal to ioo. or the record carrier according to paragraph 3. (5) Feature π [Claim 1, 2 or 3] characterized in that the middle class is 100 to 1,000 people
Record carrier as described in section. (6) Item 1 of the scope of the invention, characterized in that the reversible recording thin film is a magneto-optical thin film that records or reproduces information using a light beam as a heat source and reproduces information through interaction between magnetism and light. Record carrier as described. (7) Single point of magneto-optical thin film or operation during recording i
? lt,,l characterized by a purity of 90°C or higher
lπ1□Y! (8) The magneto-optical thin film has at least one of Gd, Tb, DV, or an amorphous alloy of I- and Fe; Add any of Ge, Sn, or Bi to crystalline T1 alloy/Here! 1. ! Claim 6 or 7, which is characterized as I', Record of Precepts J[,! body. (9) The recording Jim body according to claim 1, wherein the substrate has a track guide groove. 01 Special i'rl', +% 111g characterized in that the matrix of the substrate consists of polymethyl methacrylate-1.
The record carrier according to item 1 below.