JPH0576707B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical recording disks, particularly heat mode optical recording disks.

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.
Development research on various optical recording media is being conducted.

Among such optical recording disks, heat mode optical recording disks are being actively developed because they do not require development in a dark room.

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

Until now, most of these pit-forming type disks, especially those using a semiconductor laser as a light source that allows for miniaturization of the device, have a recording layer made of a material mainly composed of Te.

However, in recent years, it has become clear that Te-based materials are harmful.
Furthermore, due to the need for higher sensitivity and lower manufacturing costs,
There have been an increasing number of proposals and reports on media using 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 such a recording layer made of a dye or the like, it is preferable to have a so-called air sand arch structure in order to increase the number of recording layers.

In this case, the air sandwich structure uses a pair of optical recording parts each 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. It is.

Conventionally, in order to integrate both optical recording parts in a disk with an air sandwich structure, a ring-shaped connecting member made of resin as a spacer is interposed in the center and the peripheral part, and this and the substrate of both optical recording parts are connected. This is done by gluing 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 substrates tend to shift, and if this shifts, the dynamic balance during disk rotation will be disturbed.

OBJECT OF THE INVENTION The object of the present invention is to integrate a pair of optical recording parts each having a recording layer formed by coating a dye or a composition of dyes on a disk-shaped substrate so that the recording layers face each other with an air space in between. To provide an optical recording disk which has sufficient strength, has good dynamic balance during rotation, and is easy to assemble and can improve work efficiency. It's about doing.

These objects are achieved by the invention described below.

That is, in the present invention, a pair of optical recording parts each having a recording layer on the recording layer formation surface of a disk-shaped substrate having a hole in the center are integrated so that the recording layers face each other with an air space in between. In the optical recording disk, a plurality of rod-shaped protrusions are protruded from the recording layer forming surface of the inner peripheral edge of the central hole of the substrate of at least one optical recording portion, and the protrusions are brought into contact with the recording layer forming surface of the other substrate. This optical recording disk is characterized in that the inner circumferential edge of the central hole of the disk is integrated by fixing the disk with the disk.

Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below.

The optical recording disk 1 of the present invention is shown in FIGS.
As shown in FIGS. 8, 11, and 12, a pair of optical recording portions 21 have recording layers 41, 45 on disk-shaped substrates 31, 35 having a hole in the center into which a rotating shaft is inserted. , 25.

The substrates 31 and 35 used are disk-shaped and have a hole in the center into which a rotating shaft is inserted, and are made of resin that is substantially transparent (preferably with a transmittance of 80% or more) to writing light and reading light. This allows writing and reading from the back side of the substrate.

Note that the resin material used may be any of acrylic resin, polycarbonate resin, nylon, etc.

Such substrates 31 and 35 are shown in FIGS.
As shown in FIG. 8, FIG. 11, and FIG. 12, a plurality of rod-shaped protrusions 61, 62 are provided on the inner peripheral edge of the central hole.

The rod-like protrusions 61 and 62 are connected to the substrate 21,
It extends almost perpendicularly to the recording layer formation surface of No. 25.

Examples of the formation of rod-like protrusions in the present invention include:
The protrusion may have a cylindrical shape as shown in FIG. 3 or a conical shape as shown in FIG. 4, but there is no particular restriction on the shape of the protrusion; for example, it may be a triangular pyramid or a quadrangular pyramid. Further, it is not necessary to limit the shape to one type of shape in particular, and a combination of several of these shapes, such as a triangular prism, a quadrangular prism, a triangular pyramid, etc., may be combined and arranged.

The diameter of such rod-shaped projections 71 and 72 is 0.2 to 6.
Approximately mm.

As an example of the arrangement of the plurality of bar-like protrusions 61, 62 on the inner peripheral edge of the central hole of the substrates 21, 25, the fifth
As shown in the figure, they may be distributed almost uniformly over the entire inner peripheral edge of the center hole of the substrate.

Further, as shown in FIG. 6, a collection of protrusions 61 may be arranged partially, particularly periodically, at the inner peripheral edge of the center hole of the substrate. In this case, in the example of FIG. 6, areas where no protrusions 61 are provided are periodically provided, but as shown in FIG.
1 may be provided sparsely. In this case, it is usually preferable that the protrusions 61 be partially arranged symmetrically on the substrate.

In addition, as in each of the illustrated examples, whether the protrusions 61 and 62 are uniformly disposed over the whole or partially disposed, the protrusions 61 and 62 may be disposed at the inner circumferential edge of the central part of the board in the radial direction 2 to 8.
Preferably, the protrusions 61 and 62 are arranged within a range of mm.

When integrating the substrates 31 and 35 using such a protrusion, as shown in FIG. There are no protrusions on the
These may be integrated. In this case, the arrangement of the protrusions may be any of those shown in FIGS. 5 to 7.

Furthermore, as shown in FIG. 2, two substrates 31 and 35 on which projections as shown in FIG. They may also be integrated together. Alternatively, two substrates on which protrusions are periodically arranged as shown in FIGS. 6 and 7 may be used, and the protrusion provided portion and non-protrusion portion may be opposed so that the protrusions 61 and 62 do not overlap. May be integrated.

In each of these cases, the protrusions 61, 6
For example, ultrasonic welding may be used for the integration via 2.

When performing ultrasonic fusion, rod-shaped protrusions 61,
62 is heated effectively, the fusion efficiency is good, the workability is good, the adhesive strength is high, and the gap can be controlled with precision.

When such ultrasonic fusion is used, the rod-shaped projections 61 and 62 are usually accompanied by various deformations.

The deformation may be performed so that an airtight inner circumferential wall is formed over the entire surface.

Fixing can also be achieved by injecting adhesive.

When injecting the adhesive, since it is injected between the protrusions, the adhesive is uniformly filled in the entire gap by capillary development, and there is no overflow of the adhesive, resulting in a good finish. Furthermore, the recording layer is not damaged. It also has extremely high mechanical strength.

In this case as well, if necessary, adhesive is injected over the entire surface to form an airtight inner circumferential wall over the entire surface.

In addition, due to strength issues, the number of protrusions is 500 ~
It will be around 3500.

In order to form such a plurality of rod-shaped protrusions, it is sufficient to process the master or stamper and integrally mold them when molding the substrate.

Such substrates 31, 35 have both recording layers 41,
45 are connected and integrated by the plurality of bar-like protrusions on the inner circumferential edge of the central hole and the plurality of bar-like protrusions on the outer circumferential edge of the substrate or the outer connecting member, etc., so that they face each other.

As a method for connecting the outer peripheral parts of the substrates 31 and 35,
Various methods are possible, and in Figures 1 to 7,
Different embodiments are shown in which the substrates 31 and 35 are connected by a plurality of bar-like protrusions provided on the outer peripheral edges thereof.

Similar to the plurality of bar-shaped protrusions 61 and 62 provided on the inner peripheral edge of the central hole on the substrate, these bar-shaped protrusions extend almost perpendicularly to the formation surfaces of the recording layers 41 and 45 on the substrates 31 and 35. ing.

Examples of the shape of the rod-like protrusion in the present invention include:
Although there are cylindrical shapes as shown in FIG. 5 and conical shapes as shown in FIG.
It may be a polygonal prism such as a quadrangular prism, a triangular pyramid, or a quadrangular pyramid. Further, it is not necessary to specifically limit the shape to one type, and a combination of several types of shapes such as a triangular prism, a quadrangular prism, a triangular pyramid, etc. may be arranged.

The diameter of such rod-shaped projections 71 and 72 is 0.2 to 0.6
Approximately mm.

Furthermore, as an example of the arrangement of the plurality of bar-like protrusions 71 and 72 on the outer peripheral edge of the substrate, they may be distributed almost uniformly over the entire outer peripheral edge of the substrate, as shown in FIG.

Further, as shown in FIG. 6, a collection of protrusions 71 may be arranged partially, particularly periodically, at the peripheral edge of the substrate. In this case, in the example of FIG. 6, areas where no protrusions are provided are periodically provided, but as shown in FIG. 7, protrusions 71 may be provided sparsely and periodically. In this case, it is usually preferable that the protrusions 71 are partially arranged symmetrically on the substrate.

In addition, as in each of the illustrated examples, whether the protrusions 71 are arranged uniformly over the whole or partially, the protrusions 71 and 72 are arranged within a range of 2 to 8 mm in the radial direction at the outer peripheral edge of the substrate. It is preferable to do so.

When integrating the substrates 31 and 35 using such a protrusion, as shown in FIG. There are no protrusions on the
These may be integrated. In this case, the arrangement of the protrusions may be any of those shown in FIGS. 5 to 7.

Furthermore, as shown in FIG. 2, two substrates 31 and 35 on which projections as shown in FIG. They may also be integrated together. Alternatively, by using two substrates on which protrusions are periodically arranged as shown in FIG. 5, both protrusions 7
The protrusion provided portion and the non-protrusion portion may be opposed and integrated so that the protrusion portions 1 and 72 do not overlap.

In this way, by fixing the protrusion and the substrate forming surface, alignment in the disk rotation direction becomes easy.

Furthermore, in addition to the embodiments shown in FIGS. 1 and 2, the connecting shape of the inner peripheral edge of the center hole and the connecting shape of the outer peripheral edge shown in FIGS. It may be a combination of

In each of these cases, the protrusions 71, 7
For example, ultrasonic welding may be used for integration via 2.

When performing ultrasonic fusion, rod-shaped protrusions 71,
72 is heated effectively, the fusion efficiency is good, the workability is good, the adhesive strength is high, and the gap can be controlled with precision.

When such ultrasonic fusion is used, the rod-shaped projections 71 and 72 are usually accompanied by various deformations.

When the deformation is large and the protrusion density is high,
A sensitive peripheral wall may be formed on the entire surface.

However, as will be described later, it is usually preferable that vent holes be formed between the partition walls.

In the example shown in Fig. 6, the ventilation holes are located between the protrusions and the 5th hole.
In the example shown in FIGS. 7 and 7, the protrusions are formed in a portion where no protrusions are provided or a portion where protrusions are sparsely provided.

Fixing can also be achieved by injecting an adhesive.

When injecting the adhesive, since it is injected between the protrusions, the adhesive is uniformly filled in the entire gap by capillary development, and there is no overflow of the adhesive, resulting in a good finish. It also has extremely high mechanical strength.

In this case, an airtight outer peripheral wall can be formed over the entire surface by injecting the adhesive over the entire surface, if necessary.

However, usually the adhesive is injected only in the desired area,
Preferably, a vent is left.

In such a case, as described above, only the desired portions can be bonded accurately, which is extremely advantageous in terms of manufacturing.

In addition, due to strength issues, the number of protrusions is 100~
It will be around 2000.

Further, the vent hole formed between the protrusions 71 and 72 has a total size of about 0.01 to 100 mm ² .

By providing a plurality of rod-shaped protrusions on the substrate in this manner, gaps are created between the protrusions, and the occurrence of distortion in the substrate can be prevented in the same manner as described above.

Further, a filter may be placed close to the protrusions 71, 72, etc. to prevent the influence of dust and dirt.

In order to form such a plurality of rod-shaped protrusions, it is sufficient to process the master or stamper and integrally mold them when molding the substrate.

FIGS. 8, 9, and 10 show an embodiment in which an outer connecting member 5 is used as a method of connecting the outer peripheral portion of the substrate.

The substrates 31 and 35 are shown in FIGS. 8, 9 and 1.
As shown in FIG. 0, it has a plurality of grooves 8.

In the examples in these figures, the shape of the groove is a sector with a tapered surface. The dimensions of groove 7 are usually the radius
The length is approximately 0.3 cm to 1.0 cm, but it is sufficient as long as it is longer than the radial length of the connecting member 5. The fan-shaped opening angle is about 5° to 60°. From the viewpoint of strength, the depth of the groove is approximately 1/2 to 1/10 of the thickness of the substrate.

The shape of the groove may be other than the above-mentioned example, and the dimensions of the groove may be appropriately determined in consideration of the possibility that dust and dirt may enter the inside of the cavity.

Although it is not always necessary to provide a groove on the substrate, by providing a groove on the substrate in this way, the outside and the inside communicate, and it is possible to prevent the occurrence of distortion in the substrate due to pressure differences. , it is more preferable to provide a groove.

Further, a filter may be placed inside the groove to prevent the influence of dust and dirt.

Although one such groove 7 may be provided on only one substrate, usually a plurality of such grooves 7 are arranged symmetrically on both substrates 21 and 25.

To form such grooves, stamper processing, grinding processing, or formation at the time of substrate molding may be used.

Such substrates 31, 35 have both recording layers 41,
The outer connecting member 5 and a plurality of rod-shaped protrusions 61 and 62 on the inner circumferential edge of the central hole are connected to each other so that the outer connecting members 5 and 45 face each other and are integrated.

In this case, the shapes of the plurality of bar-like protrusions 61, 62 may be any shape as shown in FIGS. 1 to 4.

The outer connecting member 5 is ring-shaped, and as shown in FIG. 8, its outer diameter is equal to that of the substrate.

Thereby, when the two substrates 31, 35 and the connecting member 5 are connected, the inside and outside are communicated through the groove 8.

The connecting member 5 used may have various shapes and may be made of various materials, but is usually made of resin and is bonded or fused to the substrates 31 and 35 of the optical recording portions 21 and 25. It is worn.

FIG. 11 shows an embodiment in which a ring-shaped protrusion is provided on the peripheral edge of one of the substrates to connect them, as yet another method of connecting the outer peripheral portions of the substrates.

In the example shown in FIG. 11, the substrate 31 has a ring-shaped protrusion 311 along the peripheral edge. This protrusion 3
Although the cross-sectional shape of 11 is shown as a rectangle in this figure, there is no need to limit it in particular, and various shapes can be considered, and it may be determined as appropriate. For example, when performing ultrasonic fusion, it is preferable that the shape of the portion in contact with the fusion surface is an edge shape (for example, a triangular tip) so that the ultrasonic waves are concentrated.

In addition, the cross-sectional shape of the protrusion at any position in the radial direction usually has the same shape, but if necessary, the ring-shaped protrusion shape can be set so that it has a different cross-sectional shape at a predetermined position. Good too.

It is preferable that such a ring-shaped protrusion 311 be provided in a range of 2 to 8 mm in the radial direction at the peripheral edge of the substrate.

Further, on one of the substrates 35, the above-mentioned FIGS.
As in the case of FIG. 0, it has a plurality of grooves 8.

It is preferable to provide a groove on the substrate because it allows communication between the outside and the inside and prevents distortion of the substrate due to pressure differences. The length of the groove 8 in the radial direction is usually about 0.3 cm to 1 cm, but it is sufficient as long as it is longer than the length of the ring-shaped protrusion 311 in the radial direction. The width and depth of the groove are the same as in the previous case.

Such substrates 31, 35 have both recording layers 41, 4.
5 are connected to each other by a ring-shaped protrusion 311 and a plurality of rod-shaped protrusions 61 and 62 on the inner peripheral edge of the central hole so that they are integrated.

In this case, the shape of the plurality of bar-shaped protrusions 61, 62 is as follows.
As in the case described above, it may have any of the shapes shown in FIG. 1 and FIG. 2.

As a result, when the two substrates 31 and 35 are connected, the inside and outside communicate with each other through the groove 8.

Furthermore, FIGS. 12 to 15 show an embodiment of another method of connecting the outer peripheral portion of the substrate.

As shown in FIGS. 12 to 15, the substrates 31 and 35 have a plurality of protrusions 91 integrally formed on their peripheral edges. In the illustrated example, the shape of the protrusion is a fan-like shape with the center on the inside, but there is no particular restriction on the shape of the protrusion. , its upper surface may be convex.

Further, unlike the illustrated example, the protrusions 91 are not provided in an upright, continuous and scattered manner, but are provided in a continuous ring shape as a whole, and one or more notches are provided in a part of the protrusions 91. It is also possible to provide one.

However, as shown in the figure, if the protrusions 91 are provided integrally with the substrate to form a fan-shaped column and the center of the fan-shape is directed toward the center of the disk, the recording layer 41 of a dye-based material, etc.
When spinner coating 45, the protrusion 7 of the substrate
This is preferable because it can easily prevent the coating material from remaining and scattering around the recording area and contaminating the recording area.

In this case, the opening angle of the fan-shaped protrusion 91 is approximately 5° to 90°.

A plurality of such protrusions 91 are provided integrally with at least one of the substrates.

In this case, the protrusion 91 may be provided only on one substrate. At this time, the protrusion 9 provided on the board
The number and size of the vents are determined according to the number of vents, their spacing, and their height.

Further, the protrusion 91 may be provided on both substrates.

At this time, the protrusions 91 and 92 may be provided on both substrates so as to be mirror images, and the protrusions on both substrates may be fixed to each other.

Alternatively, as shown in FIG. 15, the protrusions 91 and 92 provided on both substrates may be integrated so that the protrusions 91 and 92 provided on both substrates do not overlap each other, and the adjacent protrusions 91 and 9
The vent hole 10 may be formed between two spaces.

In each of these cases, it is preferable to provide about 2 to 8 vent holes and to arrange them symmetrically over the entire disk. Also, the dimensions of the ventilation hole are height (usually equal to length) 0.1 to 0.8
mm, and the width is preferably about 0.1 to 10 mm.

Note that in some cases, both substrates 31 and 35
When the protrusions 91, 92 are provided, the protrusions 91, 92
A ring-shaped spacer may also be interposed between them.

In this manner, by providing the protrusions 91 and 92 on the substrate and forming the vent 10, the outside and the inside are communicated with each other, and distortion of the substrate due to pressure difference can be prevented.

Further, a filter may be placed in the space (ventilation port 8) created by the protrusion to prevent the influence of dust and dirt.

In order to form such a protrusion, the master or stamper may be processed and integrally molded when molding the substrate.

Such substrates 31, 35 have both recording layers 41,
45 are opposed to each other, the protrusion 91 on the peripheral edge of the substrate
and multiple rod-shaped protrusions 61, 6 on the inner peripheral edge of the central hole.
2 and are integrated. In this case as well, the plurality of rod-shaped protrusions 61, 62
The shape may be any of the shapes shown in FIGS. 1 and 2.

Recording layers 41, 45 of such substrates 31, 35
It is preferable that tracking grooves be formed on the forming surface.

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

The recording layer 41 located in the recessed part of this groove,
It is preferable that writing light and reading light are irradiated from the back side of the substrate by using 45 as a recording track section.

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, it is preferable to use a semiconductor laser as the light source since the device can be made smaller, so the dye may be cyanine-based, phthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based, pyrylium or thiapyrylium salt-based. etc. 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 bisphenyldithiol is particularly preferred.

It is also preferable to use them as ionic combinations of the cations of these dyes and the anions of quenchers.

The recording layer may be formed by spinner coating or the like using a ketone, ester, ether, aromatic, halogenated alkyl, or alcohol solvent.

Such recording layers 41 and 45 have a thickness of 0.01 to 10 μm.
It is preferable to set the thickness to .

In addition, when coating the recording layer, the viscosity of the coating solution is
0.5~10cp, spinner rotation speed is 500~1000rpm
degree.

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 or less, more preferably 0.05 to 0.15 μm.
It is preferable that

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 becomes large, making tracking control easier.

A layer above the recording layer or an underlayer can also be provided on such an optical recording portion.

Specific Effects of the Invention The optical disk of the present invention irradiates writing light from the back side of the substrate while rotating. As a result, pits are preferably formed in a track shape in the recording track portion located in the groove recess.

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

Additionally, to control tracking,
While writing and reading, the reflected light is divided and introduced into a pair of divided sensors. At this time, when the beam spot begins to deviate from the recording track section, the primary light due to the interference effect due to the phase difference due to the step in the groove is biased towards one sensor, so the signals from both sensors are detected and a track error signal is detected. Ru.

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

In addition, various lasers can be used as the light source used for writing and reading, but
In particular, it is preferable to use a semiconductor laser.

Specific Effects of the Invention According to the present invention, when the substrates are bonded or fused, there is no displacement of the spacer or displacement between the two substrates, so the dynamic balance during rotation is improved.

Moreover, the strength at the center of the disk is extremely high, and its life is significantly increased.

Furthermore, since the disk according to the present invention is easy to manufacture, accuracy can be improved and mass production can be achieved, thereby reducing costs.

In the present invention, since a plurality of rod-shaped protrusions are integrally molded on the inner peripheral edge of the center hole of the substrate, the number of parts can be reduced, and as a result, manufacturing costs can be reduced.

Furthermore, it can be manufactured without adversely affecting the coating properties of the recording layer.

Further, according to the present invention, since rod-shaped protrusions are used, if these are ultrasonically fused, the strength is high and it is advantageous in terms of manufacturing.

Furthermore, when injecting the adhesive, the injection is uniform, the strength is high, and the finish is good.

In each of these cases, the recording layer is not damaged.

Further, vent holes can be formed very easily in the outer peripheral edge of the substrate using various methods.

At this time, since the air pressure inside and outside the air are equalized, deformation of the substrate due to distortion can be prevented and good recording or reproduction can be achieved.

[Brief explanation of the drawing]

Figure 1, Figure 2, Figure 8, Figure 11 and Figure 1
FIG. 2 is a sectional view showing different embodiments of the optical recording disk of the present invention. Figures 3 and 4
10 and 14 are partially enlarged perspective views of a substrate, which is a component of the optical recording disk of the present invention. FIG. 5, FIG. 6, FIG. 7, FIG. 9, and FIG. 13 are respectively plan views of substrates that are parts of the optical recording disk of the present invention. 15th
The figure is a plan view showing an embodiment of the optical recording disk of the present invention. Explanation of symbols, 1... Optical recording disk, 21, 2
5... Optical recording part, 31, 35... Substrate, 311
...Ring-shaped protrusion, 41, 45...Recording layer, 6
1, 62... Rod-shaped projection (inside), 71, 72...
Rod-shaped projection (outside), 8... groove, 91... protrusion,
10...time.

Claims (1)

[Claims] 1. A pair of optical recording parts each having a recording layer on the recording layer formation surface of a disk-shaped substrate having a hole in the center are integrated so that the recording layers face each other with an air space in between. In this optical recording disk, a plurality of rod-shaped protrusions are protruded from the recording layer forming surface of the inner peripheral edge of the central hole of the substrate of at least one optical recording portion, and the protrusions are brought into contact with the recording layer forming surface of the other substrate. 1. An optical recording disk characterized in that an inner peripheral edge of a center hole of the disk is integrated with the inner peripheral edge of the disk by fixing the disk in a fixed manner.