JPS63144439A - Optical recording disk and its production - Google Patents

Abstract

PURPOSE:To easily and accurately attach an optical recording disk magnetically onto a disk mounting board by unifying a hub part having a center hole part and containing a magnetizing member with the disk inner peripheral part of a substrate containing a record layer. CONSTITUTION:An optical recording disk 1 has a pair of optical recording parts 21 and 25 including record layers 41 and 45 on the disk-shaped substrates 31 and 35 having projecting hub parts 5 at the center parts respectively. The parts 5 include the hole parts 55 and the resin substantially transparent to the write/read beams (with preferably >=80% transmission factor) is used to both substrates 31 and 35. Thus the write/read actions are possible through the rear sides of these substrates and therefore the production yield is improved for both substrates 31 and 35 together with an easy assembling job and high accuracy. As a result, the disk 1 has a satisfactory dynamic balance in its working mode. In addition, the disk 1 can be fixed easily and accurately onto a disk mounting board.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording disk, particularly a heat mode optical recording disk and a method for manufacturing the same.

Prior art optical recording disks have the characteristic that the recording disk does not deteriorate due to wear and tear because the medium and the writing or reading head are not in contact with each other, and for this reason, research and development of various optical recording media are being carried out.

Among such optical recording discs, in the darkroom.

Heat mode optical recording disks are being actively developed because they do not require any development processing.

This heat mode optical recording disk is an optical recording disk that uses recording light as a force. For example, a part of the medium is melted or removed using recording light such as a laser, and a part of the medium is melted or removed to form a pit. There is a pit-forming type in which writing is performed by forming small holes, information is recorded using the pits, and reading is performed by detecting the pits with a readout light.

Most of these bit-forming type disks, particularly those using a semiconductor laser as a light source that can make the device smaller, have a recording layer made of a material mainly composed of Te.

However, in recent years, it has been discovered that Te-based materials are harmful, and
Due to the need for higher sensitivity and lower manufacturing costs, an increasing number of proposals and reports are being made about media that use recording layers made of organic materials, mainly dyes, instead of Te-based ones. (Japanese Patent Application No. 59-019715, etc.).

In an optical recording medium having a recording layer made of such a dye, S
In order to improve the /N ratio, a so-called air sandwich structure is preferable.

In this case, the air sand inch structure uses a pair of optical recording parts having a recording layer on a transparent resin substrate, and integrates them so that the recording layers face each other with a predetermined gap in between. .

Conventionally, in order to integrate both optical recording parts in a disc with an air sand inch structure, a resin ring-shaped connecting member was interposed as a spacer in the center and the peripheral part, and this was bonded to the substrate of both optical recording parts. This is done by fusing or fusing.

However, when such a spacer is used, its strength may be insufficient depending on its shape.

Furthermore, during adhesion, the spacer tends to shift, especially in the center, and the two plates tend to shift, and if this shifts, the dynamic balance during disk rotation will be disturbed.

Therefore, as a technique for dealing with this problem, the present inventors proposed a method in which a plurality of rod-shaped protrusions are first provided on the outer and/or inner circumference of the substrate, and the two substrates are integrated via the protrusions. (Japanese Patent Application No. 59-203284, etc.).

However, since this method uses bar-shaped protrusions, stress is applied to the bar-shaped protrusions when the substrate is separated from the mold after injection molding, causing cracks to occur at the bottom of the bar-shaped protrusions, which reduces the manufacturing yield of the substrate. Deteriorate.

Furthermore, when the substrates are integrated through the rod-shaped protrusion by ultrasonic fusion, it is not easy to precisely control the gap length between the two substrates. Note that the same applies to the case of single-sided recording in which the optical recording portion and the protection plate are integrated.

In order to solve such problems, the present inventors provided a protrusion or convex part on the substrate having a base and a melted part provided on the base, and integrated the disks via this melted part. (Patent application 15491/1982)
No. 2, Patent Application No. 1983-53206, Patent Application No. 1983-262
No. 450).

According to this method, an optical recording disk with extremely good rotational characteristics etc. can be manufactured at a high production yield without causing the above-mentioned problems.

Currently, there is a demand for the development of such an optical recording disk that can be magnetically fixed to a disk mounting plate, especially a magnetic chuck.
In order to meet this demand, the present inventors have proposed integrating the disks via a magnetically attachable hub member (patent application dated December 5, 1988).

As shown in FIG. 15, this optical recording disc has a pair of optical recording parts 121 and 125, each having a recording layer 41 and 45 on disc-shaped substrates 131 and 135 having a hole in the center into which a hub member 150 is fitted. and a hub member 150.

The hub member 150 has a magnetically attracted member 61 as shown in FIG.
．． The main body 157 is ring-shaped and has a hole in the center into which a rotating shaft is inserted, and ring-shaped rib portions 158 and 159 are provided at both ends of the outer periphery in the thickness direction.

However, in this method, the magnetically attached member 61 is attached to the hub member 150.
．． The process of attaching the magnetic member 65 is increased, and the magnetic attachment member 61
．． 65 has a problem in that it is complicated to increase the accuracy of the position.

■Object of the Invention The object of the present invention is to integrate a pair of optical recording portions each having a recording layer on a disc-shaped substrate so that the recording layer faces each other with a gap in between, or to form a pair of optical recording portions that have a recording layer on a disc-shaped substrate, or to In an optical recording disk formed by integrating a protective plate and a recording layer so as to seal the recording layer with a gap, the manufacturing yield of the substrate is high;
An optical recording disk that is easy to assemble, has high precision, has good dynamic balance during use, and can be magnetically fixed easily and reliably on a disk mounting plate, and a method for manufacturing the same. Our goal is to provide the following.

■Disclosure of invention Such objects are achieved by the invention described below.

That is, the first invention has a pair of disk-shaped substrates, has a recording layer on at least one of the substrates, and arranges both substrates so that the recording layer is located inside and a gap exists on the recording layer. An integrated optical recording disk, characterized in that the substrate having the recording layer has a magnetically attachable hub portion having a hole in the center and having a built-in magnetic member on the inner circumference of the disk. It is an optical recording disc.

Further, the second invention includes a pair of disk-shaped substrates,
A method for manufacturing an optical recording disk in which a recording layer is provided on at least one substrate, both substrates are integrated such that the recording layer is located inside and a gap exists above the recording layer, the hub portion being integrally formed. During injection molding, a magnetic member is built into the hub, and a hole is formed in the center of the hub during or after the injection molding, and furthermore, recording is performed on the substrate. A method for manufacturing an optical recording disk, characterized by including a step of coating a layer.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

Embodiments of the optical recording disk of the present invention are shown in FIGS. 1-14.

As shown in FIG. 4, the optical recording disk 1 includes a pair of optical recording portions 21.2 having a recording layer 41.45 on a disk-shaped substrate 31.35 having a convex hub portion 5 in the center.
5.

As shown in FIGS. 1 to 7, the substrate 31.35 to be used has a disk shape that integrally has a convex hub portion 5 with a hole 55 in the center, and is resistant to writing light and reading light. , made of a substantially transparent (preferably transmittance of 80% or more) resin. This allows writing and reading from the back side of the substrate.

The diameter of the substrate 31.35 is usually about 90 to 300 mmφ.

Note that the resin material used may be any of acrylic resin, polycarbonate resin, TPX, nylon, and the like.

As shown in FIGS. 1 to 7, such a substrate 31 has a convex hub portion 5 at the center of the disk.

The hub portion 5 includes a main body 51 protruding toward the side opposite to the surface on which the recording layer is formed of the substrate 31, and a hole portion 55 at the center of the substrate 31.35.
A magnetic member 61 is provided on the end surface of the protruding surface of the main body 51 opposite to the surface on which the recording layer is formed.

The main body 51 is usually ring-shaped, but may have various shapes as necessary.

The dimensions of the hub portion 5 are such that the diameter of the main body 51 is 20 to 40 mm.
mm, and the protrusion height of the main body 51 from the substrate 31 is 0.6 mm.
~2.0mm, the diameter of the hole 55 is 2~6rnll+
That's about it. Moreover, the shape of the hole 55 may be cylindrical or prismatic.

The hole 55 may completely penetrate the substrate 31, and the hole 55 may be formed on the protruding surface side of the main body 51 and has a depth that allows the center position defining protrusion 101 of the magnetic chuck 100, which will be described later, to be inserted therein. It may also be a concave portion with a hole in it. The depth of the hole 55 in this case is about 1 to 15 mm.

Further, the thickness of the portion of the board 31 excluding the hub portion 5 is 1. 2
~1. It is about 5111111.

Such a hub portion 5 has the magnetic member 61 built in near the end surface of the protruding portion of the main body 51, as described above.

The magnetic member 61 is integrally attached to the hub portion 5 at the same time as the substrate 31 is manufactured.

That is, the substrate 31 is usually formed by injection molding.

When injection molding is performed, a stand bar is usually housed in a mold with a predetermined shape, the protruding surface side of the hub portion 5 of the substrate 31 is molded, and the side of the recording layer forming surface of the substrate 31 is processed with a stand bar. The central part of the disk on the side of the hub protruding surface of the mold (Figures 1 to 3)
In the example shown in the figure, a gate is provided either at the arrow a) or at the center of the disc on the stanbar side (arrow b in the examples shown in Figures 1 to 3), and the molten resin is injected from this gate. .

In the present invention, when forming the substrate by such injection molding, the magnetic member is also integrally attached at the same time.

That is, the magnetic member 61 is installed in advance on the bottom surface of the recess of the mold corresponding to the end surface of the protrusion of the main body 51 of the hub portion 5, and then injection molding is performed, and the molten resin injected into the mold is attached to this magnetic material. By cooling and solidifying the attachment member 61 while holding it, the attachment member 61 is attached and formed in one piece.

like this! The material of the fi attachment member 61 is not particularly limited as long as it is a soft magnetic material, and for example, iron, stainless steel, etc. are preferably used.

Further, the magnetically attracting member 61 is usually in the shape of a flat ring, and only needs to have a thickness of about 0.1 to 1 mm and an area of about 1 cm2 or more, and even if it is a continuous ring, the width changes periodically. It may be of any shape.

Further, the magnetically attracting member 61 only needs to have the above-mentioned area,
As shown in FIGS. 1 and 2, it may be attached to the entire end surface of the protrusion of the main body 51, or as shown in FIG. 3, it may be attached to a part of the end surface of the protrusion of the main body 51. may have been done.

However, if the mounting position of the magnetically attracted member 61 is offset in one direction with respect to the center of the disk, the dynamic balance during rotation of the optical recording disk will be significantly degraded. Therefore, the position at which the magnetically attracting member 61 is previously installed in the mold is extremely important.

In this way, in the present invention, since the WL attachment member 61 is integrated at the same time when forming the substrate 31, for example, the outer diameter and/or inner diameter of the flat ring shape of the magnetic attachment member 61 is adjusted to the shape of the main body 51 of the mold.
By aligning the outer diameter and/or inner diameter of the bottom surface of the recess corresponding to the protrusion, the magnetic member 61 can be installed very accurately and easily in the center of the disk. In particular, the center of the disk and the center of the hub are aligned, and the eccentricity of the group is reduced.

In addition, as shown in FIGS. 1 to 7, the part of the magnetic member 61 that is in close contact with the resin material of the substrate 31 is provided in order to strengthen the adhesion between the magnetic member 61 and the resin material. It is preferable to provide various claw-like irregularities, protrusions, etc. for the purpose of forming part of the anchor.

In such a case, the hole 55 is formed as follows.

That is, when the hole 55 is not provided as a through hole but as a recess as shown in FIG. 2, the gate position is set on the side opposite to the hub protruding surface, that is, on the side where the recording layer is formed (arrow b in the figure).
If so, the holes 55 are formed during injection molding.

Then, as shown in FIGS. 1 and 3, the hole 5
When 5 is a through hole, the through hole may be formed at the same time as the spool is removed after injection molding is performed from the gates indicated by arrows a and b.

Gate dimensions, NfA degree during injection, injection speed, etc. may be within normal conditions.

Furthermore, as shown in FIG. 3, convex portions 71 and 81 may be provided on the outer and/or inner circumferential portions of the recording layer forming surface of the substrate 31 (the side opposite to the hub protruding surface).

The optical recording disk 1 of the present invention is manufactured by forming a recording layer on a substrate having such a hub portion 5 by coating as described below, and then integrating the layer by various methods as described below.
is magnetically fixed by a magnetic chuck 100 via a magnetic member 61, as in the example shown in FIG.

Moreover, the fixed position is a protrusion for defining the center position of the magnetic chuck 100! It is precisely regulated by 01.

When integrating the substrates used in the present invention, various known methods may be followed, and protrusions, spacers, etc. provided on the substrates may be used.

However, in the case of double-sided recording in terms of productivity and accuracy, it is necessary to provide multiple convex portions on the outer and/or inner periphery of at least one substrate, or to provide a disc-shaped or spoke-like shape between the two substrates. It is preferable that a spacer is disposed, a plurality of convex portions are provided on the outer and/or inner circumferential portions of both sides of the spacer, and the spacers are integrated via these convex portions.

In the case of single-sided recording, it is preferable that a plurality of convex portions be provided on the outer and/or inner circumferential portions of at least one of the substrate and the protection plate, and the substrate and the protective plate be integrated via the convex portions.

In FIG. 4, among the substrates 31°35 having the hub portion 5,
A convex portion 75.85 is provided on the substrate 35.

In FIG. 5, a spacer 91 is arranged between the substrates 31° 35 having the hub portion 5, and convex portions 71, 75.8'l, 85 are provided on the outer and inner peripheries of both sides of the spacer 91. It is something.

Roughly speaking, in FIG. 6, a protection plate 95 is arranged on the recording layer 41 formation side of the substrate 31 having the hub portion 5, and convex portions 75.85 are provided on the outer and inner circumferences of this protection plate 95. It is.

Although not shown in the illustrated example, in the case where the convex portions 71, 81 and the convex portions 75.85 are provided on both of the substrates 31.35, the convex portions 7
1 and 75 and the protrusions 81 and 85 may be provided so as to mesh with each other, or may be provided so as to have a mirror surface relationship with each other.

Such convex portions 71, 75, 81.85 are formed on the substrate 31.3.
No. 5 recording layer forming surface or spacer 91, protective plate 95
extends almost perpendicularly to the surface facing the substrate.

Furthermore, the shape of the convex portion used in a preferred embodiment of the present invention will be explained using FIGS. 8 to 14. FIG. 8 shows an example of the shape of the convex portion. In the figure, a convex portion 71 provided on the outer periphery of the substrate 31 has a base portion 711 in the shape of a truncated cone. And this base 7
11 is provided with a conical or truncated conical protrusion-like melting part 715 that rises steeply from the base 711.

The base portion 711 does not substantially deform during fusion bonding, which will be described later, and primarily plays the role of maintaining the gap length.

Further, the melting portion 715 effectively generates heat during M-sonic welding to perform melting and bonding, and has a steep slope and a small cross-sectional diameter.

The shape of the base 711 of the convex portion 71 and the melted portion 715 is similar to that of the substrate 3.
Any shape may be used as long as it does not generate unnecessary stress on the convex portion 71 when the substrate 31 is separated from the mold after injection molding in step 1.

As such, the base 711 extends from the substrate 31 at a gentle angle, and the top planar shape of the base 711 and the bottom planar shape of the melting part 715 match, and the melting part 7
15 is preferably one that rises steeply from the base 711 with respect to the substrate 31.

Further, in this case, the top of the protruding fused portion 715 is sharp,
It may have either a curved or flat shape. For example, in addition to the truncated cone-cone combination as shown in FIG. 8, combinations such as truncated pyramid-pyramid, hemisphere-cone, truncated cone-truncated cone, hemisphere-truncated cone, etc. may be used.

On the other hand, if the base has a flat top surface and a melted part is present in the center, stress will be applied to the melted part during molding, which is undesirable. That is, it is preferable that the top surface of the base portion and the bottom surface of the melting portion are connected and coincident with each other.
It is also necessary that the slope of the melted part be larger than the slope of the base.

Note that the base portion 711 and the melting portion 715 are usually continuous in a broken line shape.

In addition, a steep melting part 7 gradually rises from the base 711.
It may form a series of continuous curves transitioning to 15.

The diameter of the bottom of the base 711 of such a convex portion 71 is 0.5~
The diameter of the top of the base 711 and the bottom of the melting part 715 is preferably about 0.1 to 3 mm.

Further, the height of the base portion 711 is preferably about 0.3 to 0.8[+[11], and the height of the melting portion 715 is preferably about 0.2 to 0.511 Im.

As an example of the arrangement of a plurality of convex portions on the substrate, spacer or protective plate, they may be distributed almost uniformly over the entire outer circumference and/or inner circumference; They may be arranged partially, particularly periodically, in the circumferential direction of the . In this case, it is usually preferable that the convex portions are partially arranged symmetrically on the substrate.

In addition, whether the protrusions are arranged uniformly throughout or partially, the protrusions should be arranged within a range of 2 to 8 mm in the radial direction on the inner and outer peripheries of the substrate, spacer, or protective plate. It is preferable.

In addition, FIGS. 9 and 10 also show other shapes of the convex portions.
An example is shown.

The convex portion 71 shown in the figure is formed by arranging truncated conical protrusions on a certain inner circumference on the substrate 31 so that their bottom surfaces overlap.

As a result, the bottoms of the truncated cones overlap each other, and their top surfaces touch, forming a base 7 that continues in a ring shape in the circumferential direction.
11 is formed.

Further, on the top surface of each truncated cone of the base 711, a molten portion 715 in the form of a cone or truncated cone-shaped protrusion is provided that steeply rises from the base 711, with the bottom surfaces touching each other in the circumferential direction. It turns out.

Other shapes of the convex portion 71 are shown in FIGS. 11 and 12.

In the convex portion 71 shown in the figure, the bottom surfaces of the truncated conical bases 711 overlap, but the top surfaces thereof do not overlap, and the fused portions 715 are arranged on the top surfaces without their bottom surfaces touching each other in the circumferential direction. has been done.

Note that, unlike this case, depending on the case, if the tops of the melting portions 715 do not overlap with each other, the bottom surfaces thereof may be configured to overlap.

In this way, the convex part 71 includes a base part 711 that continues in the circumferential direction, and a plurality of protrusion-shaped melted parts 71 that are integrally provided on this base part 711 so as to rise steeply from the base part 711.
5.

The base portion 711 generally has only to be continuous in a song shape, and its cross-sectional shape is not particularly limited. However, the base 71
1 preferably has a larger cross section than the fused portion 715 and functions as a spacer during fusion as described below.

Note that, if necessary, a part of it can be cut out to form a vent.

Further, the melting portion 715 effectively generates heat during ultrasonic welding to perform melting and bonding, and has a steep slope and a small cross-sectional diameter.

The shape of the base 711 of the convex portion 71 and the melted portion 715 is similar to that of the substrate 3.
When the substrate 31 is separated from the mold after injection molding in step 1, any shape is sufficient as long as it does not generate unnecessary stress on the convex portion 71, and the base portion 711 as shown in FIGS. 31 at a gentle angle, and this base 711
The top planar shape of the melting portion 715 matches the bottom planar shape of the melting portion 715, and the melting portion 715 rises steeply from the base portion 711 with respect to the substrate 31.

In this case, the inclination angle of the base 711 with respect to the substrate 31 is 30
A culm degree of ~60°, particularly about 40 to 50° is preferred. Further, the inclination angle of the melted part 715 with respect to the substrate 31 is 45 to 8
It is preferably about 0°, particularly about 50 to 70°.

Further, in this case, the top of the melted portion 715 may have any shape of a sharp point, a curved shape, or a flat shape. For example, the shapes of the base portion 711 and the melting portion 715 include, in addition to the truncated cone-truncated cone combination as shown in FIGS. It may be a combination of truncated cones and the like.

On the other hand, a material in which the base has a flat top surface and a melted part in the center is not preferable because stress is applied to the melted part during molding. That is, it is preferable that the top surface of the base portion and the bottom surface of the melting portion are connected and coincident with each other.
It is also necessary that the slope of the melted part be larger than the slope of the base.

Note that the base portion 711 and the melting portion 715 are usually continuous in a broken line shape. Alternatively, it may form a series of continuous curves that gradually rise from the base portion 711 and transition to a steep melting portion 715.

In addition to the preferred examples described above, the shape of the convex portion may be as shown in FIGS. 13 and 14.

That is, for example, as shown in FIG.
The inclination angles of the melting part 1 and the melting part 715 with respect to the substrate 51 may be the same.

Further, the convex portion 71 shown in FIG. 14 is formed on the substrate 31.
It has a ring-shaped base 711 with a trapezoidal cross section. and,
On the upper surface of this base 711, a plurality of conical protrusion-shaped melting portions 715 are arranged in the circumferential direction with their bottom surfaces touching each other.

Generally, the convex portions 71 may be arranged in one row on a constant circumference as shown in the illustrated example. If the bottom surfaces of the melting portions 715 are arranged so as to be in contact with each other, melt adhesion can be ensured.

However, depending on the case, it is of course possible to arrange a plurality of rows of convex portions 71 concentrically or to change the density of the fused portions 715 periodically or non-periodically on the circumference. .

In such a case, in order to integrate the substrates via the convex portion 71, fusion bonding, particularly ultrasonic fusion bonding, is performed as described later.

During this fusion, the protruding molten portion 715 effectively generates heat, melts itself, and performs fusion bonding. On the other hand, the wide-diameter base 711 at the lower part of the melting part 715 is hardly deformed and functions as a spacer.

Therefore, the height of the base 711 is approximately the same as the gap length in the air sandwich structure, and is generally 0.1
It should be about 2 mm. Further, the diameter of the base 711 in the disk radial direction may generally be about 1 to 5 mm.

On the other hand, the melting part 715 usually has a height of 0.1 to 0.3 mm.
The bottom diameter is approximately 0.1 to 0.3 mm.

The integration of the substrates 31 and 35 through such a convex portion is as follows.
Generally, ultrasonic fusion may be used.

When performing ultrasonic welding, the melted portion 715 of the convex portion 71 is effectively heated and subjected to welding, and the base portion 711 remains in its original shape.

Therefore, the fusion efficiency is good, the workability is good, and the adhesive strength is also high.Furthermore, since the gap distance is determined by the height of the base 711, it can be controlled by the stacking density.

Note that when the above-mentioned vent hole is provided, a filter may be provided to prevent the influence of dust and dirt.

In order to form such a convex portion, a mold, a master disk, or a stub bar may be processed and integrally molded at the time of substrate molding.

It is preferable that a tracking groove be formed on the surface of the substrate 31, 35 on which the recording layer 41.degree. 45 is formed.

The depth of the groove is about λ/8n, especially λ/7n~λ
/ 12 n (where n is the refractive index of the substrate). Further, the width of the groove is approximately the width of a track.

It is preferable to use the recording layers 41 and 45 located in the recessed portions of the grooves as recording track portions, and to irradiate the writing light and the reading light from the back side of the substrate.

With this configuration, the writing sensitivity and the reading S/N ratio are improved, and the tracking control signal is also increased.

The recording layer of the present invention preferably consists of a dye alone or a dye composition.

The dye to be used may be appropriately determined from among those that effectively absorb the wavelengths of the writing light and reading light. In this case, these light sources are
Since it is preferable to use a semiconductor laser because the device can be made smaller, the dyes may be cyanine-based, phthalocyanine-based, anthraquinone-based, azo-based, or triphenylmethane-based.
．． Byrylium or thiapyrylium salts are preferred.

Further, when the dye composition is used as a recording layer, it can contain a self-oxidizing resin such as nitrocellulose, or a thermoplastic resin such as polystyrene or nylon. Furthermore, a quencher may be included in order to prevent oxidative deterioration of the dye. Furthermore, other additives may also be included.

In such a case, a mixture of an indolenine cyanine dye and a quencher such as Ni-bisphenyldithiol is particularly preferred. It is also preferable to use these as an ionic bond between a dye cation and a quencher anion.

The recording layer can be made of ketone type, ester type, ether type,
Application such as a spinner coat may be performed using an aromatic solvent, a halogenated alkyl solvent, an alcohol solvent, or the like.

Such a recording layer 41.45 preferably has a thickness of 0.01 to 10 μm.

In addition, when coating the recording layer, the viscosity of the coating solution is 0.5~
10cp, spinner rotation speed 500~1.00Or
Approximately pm.

In addition, when providing grooves for tracking control as described above, the thickness of the recording track portion in the recording layer is 0.2 μm.
The thickness is preferably 0.05 to 0.15 μm, more preferably 0.05 to 0.15 μm.

At this time, writing sensitivity is improved. Further, due to multiple reflections in the recording layer, the reflectance becomes extremely high, and the read S/N ratio becomes extremely high. Then, the difference in reflectance based on the difference in thickness between the recording track portion and other areas increases, making tracking control easier.

In such an optical recording part, the upper layer of the recording layer or
A base layer can also be provided.

In addition, although the case of double-sided recording has been described above,
In the present invention, a single-sided recording medium may be used in which a recording layer is provided only on one substrate. In this case, one of the substrates may be opaque.

(2) Specific Effects of the Invention The optical recording disk of the present invention is magnetically attached to a magnetic chuck, and is irradiated with writing light from the back side of the substrate while being rotated.

As a result, bits are preferably formed in a track shape in the recording track portion located in the groove recess.

The bits formed in this manner are detected by emitting readout light from the back side of the substrate while rotating and detecting the reflected light.

Further, in order to control tracking, normally, while writing and reading are being performed, the reflected light is divided and introduced into a pair of divided sensors. At this time, if the beam spot begins to miss the recording track section,
Since the primary light due to the interference effect due to the phase difference due to the step of the groove is biased towards one sensor, the signals from both sensors are detected and a tracking error signal is detected.

Note that if the recording layer is formed from a dye composition containing a thermoplastic resin, the bits formed with the negative bits can be erased by light or heat, and writing can be performed again.

In addition, the light source used for writing and reading is
Although extrapolation lasers can be used, it is particularly preferred to use semiconductor lasers.

(2) Specific Effects of the Invention According to the present invention, it is possible to magnetically fix an optical recording disk to a disk mounting plate very easily and accurately, and handling is greatly improved.

Furthermore, since the magnetically attractable member is attached to the hub portion of the substrate at the same time as the substrate is formed, the process can be simplified, and furthermore, since only the deviation of the magnetically attractable member occurs when the device is installed, the dynamic balance during rotation is improved.

Since the hub member is integrated with the substrate, assembly accuracy is extremely high, dynamic balance is good, and disks with small eccentricity can be supplied, which is advantageous in manufacturing.

Further, according to a preferred embodiment of the present invention, the convex portion used to integrate the substrates has a base and a fused portion, and the protruding fused portion is formed on the base that extends upward from the substrate at a gentle angle. , the occurrence of damage due to stress applied to the convex portion during substrate formation is extremely small, and the production yield of the substrate is greatly improved.

Moreover, when the substrates are integrated, the melted parts of the convex parts fuse together,
Since the gap is determined by the base of the protrusion, assembly accuracy is improved, mass production is possible, and costs are reduced.

In addition, if the fused part of the convex part is ultrasonically fused, the strength will be high.
It is also advantageous in terms of manufacturing.

In these cases, the recording layer is not damaged.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are cut end views showing different embodiments of substrates that are components of the optical recording disk of the present invention. FIG. 4, FIG. 5, and FIG. 6 are cut end views showing different embodiments of the optical recording disk of the present invention, respectively. FIG. 7 is a cut end view showing an example in which the optical recording disk of the present invention is magnetically fixed to a magnetic chuck of a disk mounting plate. FIG. 8, FIG. 10, FIG. 12, FIG. 13, and FIG. 14 are partially enlarged perspective views of a substrate that is a component of the optical recording disk of the present invention. 9 and 11 are plan views of the substrates shown in FIGS. 10 and 12, respectively. FIG. 15 is a cut end view showing an example of a conventional optical recording disk. Explanation of symbols 1.10... Optical recording disk, 21.25, 121, 125... Optical recording portion, 31.
35,131,135...Substrate, 41.45...Recording layer, 5...Hub portion, 51...Main body, 55...Hole portion, 61.65-...Magnetic member, 71 .75,81.85--Convex portion, 711--Base, 715--Melted portion, 91--Spacer, 95--Protection plate, 100--Magnetic chuck, 101--Center Position regulating projection, 150... Hub member, 157... Ring-shaped main body, 158.159-... Ring-shaped protrusion FIG, 4 FIG, 6 FIG, 8 FIG, 10 FIG, 11 FIG , 12 F I G, 13

Claims (2)

[Claims] (1) A light beam that has a pair of disk-shaped substrates, has a recording layer on at least one substrate, and integrates both substrates so that the recording layer is located inside and there is a gap above the recording layer. What is claimed is: 1. An optical recording disk, characterized in that a magnetically attachable hub portion having a hole in the center and having a built-in magnetic member is integrally formed on the inner peripheral portion of the disk of a substrate having a recording layer. (2) A light beam that has a pair of disc-shaped substrates, has a recording layer on at least one substrate, and integrates both substrates so that the recording layer is located inside and a gap exists above the recording layer. In a method for manufacturing a recording disk, a disk-shaped substrate integrally having a hub portion is injection molded, a magnetic member is built into the hub during this injection molding, and the center of the hub portion is fixed during or after the injection molding. 1. A method of manufacturing an optical recording disk, comprising the steps of forming holes in the substrate and coating the recording layer on the substrate.