JP2003157574A - Optical disk and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that there is a limit for making an optical disk device thin because an optical disk and an optical disk cartridge can not be made thin although making a thin optical disk device is studied by various methods. SOLUTION: The disk substrate of the optical disk 1 where a recording medium layer 4 or a metallic reflecting layer 4' is to be formed is composed of a thin metallic substrate 2 and a resin layer 3 having a rugged pit pattern and/or a rugged guide groove pattern formed on the metallic substrate 2 or a resin layer 3' having a rugged pit pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc for recording or reproducing high-density information, and more specifically, an optical disc, an optical disc cartridge containing the optical disc, and an optical disc. The present invention relates to an optical disk device.

[0002]

2. Description of the Related Art Various attempts have been made to improve the portability of optical disk devices. For example, MD (Mini
Disc), a hologram pickup element in which a semiconductor laser and a photodetector are integrated by using a hologram element, an integrated pickup element in which an optical element is integrated, and the like have been developed to record and reproduce information signals. The optical pickup device is being made smaller and thinner. As a result, an MD recording / reproducing apparatus having a thickness of about 10 mm and using an MD cartridge having a thickness of 5 mm is now commercially available.

In recent years, with the aim of further thinning,
The optical disc substrate is steadily becoming thinner, and a 1.2 mm thick polycarbonate substrate was used in MD, whereas the “Feasibility Study of CAD-MSR with 7
In Gbit / in ² “MORIS'99 p.181, an optical disk with a diameter of 50 mm using a 0.6 mm thick polycarbonate substrate was presented.

[0004]

[Problems to be Solved by the Invention] Laptops and PDs
Portable information terminals such as A (Personal Digital Assistants) have a thickness of 10 mm or less, and an optical disk device that can be inserted into a card slot of such a mobile device needs to have a thickness of 5 mm or less. Become.

In order to meet this requirement, it is necessary to reduce the size of the optical pickup mounted in the optical disc device and to reduce the thickness of the optical disc cartridge and the optical disc.

However, the resin substrate such as polycarbonate used as the disc substrate (base portion of the optical disc) is generally manufactured by injection molding,
For example, when a polycarbonate disc substrate having a plate thickness of about 0.2 mm is injection-molded, the flatness required for the disc substrate cannot be obtained. Further, since the polycarbonate resin has low rigidity, if the plate thickness is about 0.2 mm, the rigidity as a disk substrate becomes insufficient, and stable rotation drive cannot be realized. Furthermore, since the thermal expansion coefficient of the recording film or reflective film made of an inorganic material formed on the disk substrate and the resin that is the material of the disk are greatly different from each other, by forming them on the substrate, the thermal expansion coefficient The difference between the two causes the substrate to warp due to the temperature change.

[0007] Recently, a disc substrate made of resin is formed thin enough to have flexibility to form a flexible optical disc, and the flexible optical disc is stabilized by using a stabilizing plate or the like. Although a technique of rotating the optical disc has been proposed, the present invention relates to an inflexible optical disc that can be stably rotated only by the optical disc without using a stabilizing plate or the like.

[0008]

The optical disc of the present invention comprises:
In order to solve the above problems, a resin layer having a concavo-convex pit pattern and a metal reflective layer are formed at least in sequence on a metal substrate, and the total thickness of the optical disc is 0.3 mm or less.

In order to solve the above-mentioned problems, the optical disc of the present invention comprises a metal substrate on which a resin layer having an uneven pit pattern and / or an uneven guide groove pattern and an optical recording layer are formed at least sequentially. It is characterized in that the thickness of the entire optical disc is 0.3 mm or less.

In order to solve the above-mentioned problems, the optical disk of the present invention has a resin layer having a concave and convex pit pattern and a metal reflective layer which are formed at least in sequence on each of the front and back surfaces of the metal substrate, and the total thickness of the optical disk. Is 0.3m
It is characterized by being m or less.

Further, in order to solve the above-mentioned problems, the optical disk of the present invention is provided on each of the front and back surfaces of the metal substrate.
A resin layer having a concavo-convex pit pattern and / or a concavo-convex guide groove pattern and an optical recording layer are formed at least sequentially, and the total thickness of the optical disc is 0.3 mm or less.

In each of the above constructions,
A disk substrate is formed by using a metal substrate and forming a resin layer having an uneven pit pattern or a resin layer having an uneven pit pattern and / or an uneven guide groove pattern on the metal substrate. Therefore, the metal substrate forming the disc substrate can secure the rigidity required for the optical disc. The necessary rigidity referred to here is a rigidity that can maintain a stable rotation operation when the optical disc is mounted in the optical disc device. More specifically, in order to speed up information recording / reproducing, Even when driven to rotate at high speed, the rigidity is such that stable rotation can be maintained without causing fluttering (vertical movement of the optical disk).

Since the metal itself has a very high rigidity as compared with the resin, it can be made very thin even if it has a rigidity required for the optical disk, and as a result, even when the optical disk itself is made thin. In addition, it is possible to suppress the fluttering of the optical disc during rotation and to perform stable rotation, so that the optical disc itself can be made thinner and the optical disc device can be made thinner.

Especially, in each of the above-mentioned constitutions, the thickness of the entire optical disc is set to 0.3 mm.
As a result, even if the optical disk cartridge is housed in a resin-made optical disk cartridge case that has been often used conventionally, the thickness of the optical disk cartridge is 2.
When the thickness is 5 mm or less, it is possible to realize an optical disk device having a thickness of 5 mm.

The present invention includes a structure in which each of the above-described optical disks of the present invention is housed in an optical disk cartridge case to form an optical disk cartridge for the purpose of suppressing the adhesion of dust to the surface of the optical disk. By using an optical disk cartridge, it is possible to reduce the occurrence of errors.

As the optical disk cartridge,
Since the optical disc cartridge case is made of metal, the thickness of the cartridge case itself can be made thin, so that the optical disc cartridge can be made thinner and the optical disc device can be made thinner.

Furthermore, the thickness of the entire optical disk cartridge is preferably 2.5 mm or less, which makes it possible to realize an optical disk device having a thickness of 5 mm.

In each of the optical disks of the present invention, the resin layer can be formed of an ultraviolet curable resin, and
A phase change recording medium or a magneto-optical recording medium can be used for the optical recording layer. Furthermore, it is desirable to provide a light-transmissive protective layer on the metal reflective layer or the optical recording layer from the viewpoint of protecting the metal reflective layer or the optical recording layer. As the light-transmissive protective layer, an ultraviolet curable resin is used. Layers formed from
It can be a layer made of a transparent resin sheet adhered with a transparent adhesive.

Further, the optical disc of the present invention can be characterized in that the rigidity of the metal substrate is 0.150 kgf · mm or more. By making the rigidity of the metal substrate satisfy the above range, it is possible to easily realize the optical disk of the present invention having the above-described actions and effects.

As the metal substrate, one made of aluminum can be used. In this case, the thickness of the metal substrate is set to 66 μm or more, so that the optical disk of the present invention having the above-described actions and effects can be easily obtained. Can be realized.

Further, as the metal substrate, one made of iron can be used. In this case, the thickness of the metal substrate is 45 μm or more, so that the optical disk of the present invention having the above-described action and effect can be easily obtained. Can be realized.

Further, as the metal substrate, one made of copper can be used. In this case, the thickness of the metal substrate is set to 53 μm or more, whereby the optical disk of the present invention having the above-described action and effect can be easily obtained. Can be realized.

Further, as the metal substrate, one made of nickel can be used, and in this case, the thickness of the metal substrate is set to 44 μm or more, whereby the above-mentioned function
It is possible to easily realize the optical disk of the present invention that exerts the effect.

Further, as the metal substrate, one made of titanium may be used. In this case, the thickness of the metal substrate is set to 55 μm or more, whereby the optical disk of the present invention having the above-described actions and effects can be easily obtained. Can be realized.

Further, as the metal substrate, one made of an iron alloy containing iron as a main component can be used, and one of them is stainless steel made of Fe, Cr and Ni. The thickness of the substrate is 43
When the thickness is at least μm, it is possible to easily realize the optical disc of the present invention that exhibits the above-described actions and effects.

Further, as the metal substrate, one made of a titanium alloy containing titanium as a main component can be used, and a titanium alloy made of Ti, Al and V can be mentioned as one of the examples. When the thickness of the metal substrate is 51 μm or more, the optical disc of the present invention having the above-described actions and effects can be easily realized.

As the metal substrate, it is possible to use a substrate made of an aluminum alloy containing aluminum as a main component, and one example thereof is duralumin composed of Al, Cu, and Mg. By setting the thickness of the substrate to 65 μm or more, it is possible to easily realize the optical disc of the present invention that exhibits the above-described actions and effects.

Further, as the metal substrate, a metal substrate made of a copper alloy containing copper as a main component may be used, and one example thereof is phosphor bronze made of Cu, Sn and P. If the thickness of the metal substrate in this case is 55 μm or more, the above-mentioned action and
It is possible to easily realize the optical disk of the present invention that exerts the effect.

The optical disk device of the present invention is an optical disk device for recording or reproducing data on or from the above-described optical disk of the present invention or the optical disk cartridge of the present invention. It is characterized in that the metal reflection layer or the optical recording layer is irradiated with light.

With such a structure, the optical disc and the optical disc cartridge of the present invention described above are
A device capable of recording or reproducing information can be provided.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical disk and an optical disk device according to the present invention will be described below with reference to FIGS.

First, the optical disc will be described with reference to FIGS.

The optical disc 1 is of a type capable of recording / reproducing and a ROM type capable of reproducing only. An optical disc 1 of a type capable of recording / reproducing is formed on a metal substrate 2 and the metal substrate 2. A resin layer 3 having an uneven pit pattern and / or an uneven guide groove pattern, and the resin layer 3
It is composed of a recording medium layer (optical recording layer) 4 formed thereon and a light transmissive protective layer 5 for protecting the recording medium layer 4. On the other hand, the ROM-type optical disc 1 that is used only for reproduction is provided with a metal substrate 2, a resin layer 3 ′ having an uneven pit pattern formed on the metal substrate 2, and a metal layer formed on the resin layer 3 ′. It is composed of a reflective layer 4'and a light-transmitting protective layer 5 for protecting the metal reflective layer 4 '. In any type of optical disc 1, the total thickness of the optical disc 1 including all the thin layers from the metal substrate 2 to the light-transmitting protective layer 5 formed thereon is 0.3 m.
m or less. The total thickness of the optical disc 1 is 0.
The reason for setting it to 3 mm or less will be described later.

FIG. 3 is a diagram showing a method of forming the optical disc 1 called the 2P method. After the metal substrate 2 is placed on the mirror plate 6 and the ultraviolet curable resin 3a to be the resin layer 3 (or the resin layer 3 ′) is applied onto the metal substrate 2,
A transparent stamper 7 having an uneven pit pattern and / or an uneven guide groove pattern (or a transparent stamper 7'having an uneven pit pattern) is pressure-bonded in the direction of the mirror plate 6 and ultraviolet rays 8 are irradiated from the transparent stamper 7 (7 ') side. Then, the ultraviolet curable resin 3a applied on the metal substrate 2 is cured. Then, by peeling the ultraviolet curable resin 3a that hardens the metal substrate 2 from the transparent stamper 7 (7 ') and the mirror surface plate 6, the uneven pit pattern and / or the unevenness on the metal substrate 2 shown in FIG. Resin layer 3 having guide groove pattern
(Or the resin layer 3 ′ having the concave and convex pit pattern) is formed, and the substrate of the optical disc 1 (disc substrate) is completed. Here, as the transparent stamper 7 (7 ′),
It is desirable that the concave and convex pit pattern and / or the convex guide groove pattern (or the concave and convex pit pattern) be formed on the surface of the glass substrate by dry etching.

5 and 6 show the optical disc 1 shown in FIG.
FIG. 3 is a partial cross-sectional perspective view showing a part of the substrate of FIG. The resin layer 3 on which the optical disc 1 is recordable and reproducible
As shown in FIG. 5, a guide groove 9 for guiding a light beam for recording / reproducing is formed in a spiral shape on the surface of the resin (the resin layer 3 in FIG. 5 has only an uneven guide groove pattern. Type). On the other hand, as shown in FIG. 6, pits 10 forming information are spirally formed on the surface of the resin layer 3'of the ROM type in which the optical disc 1 is only read. In the rewritable optical disc of the present invention, an optical disc of a type in which a tracking signal is obtained along an uneven guide groove and an address signal is obtained by an uneven pit, and a wobble guide groove which obtains both a tracking signal and an address signal only by the uneven guide groove The present invention can be applied to an optical disk of a type called a method and an optical disk of a type called a sample servo method in which both a tracking signal and an address signal are obtained only by uneven pits.

The metal substrate 2 is made of metal and has a thickness without flexibility.
The rigidity of the non-flexible metal substrate is 0.150 kgf
It has been confirmed that it is not less than mm, and more preferably that it is not less than 0.24 kgf · mm. The reason will be described later.

Within the range of the rigidity, the material is, for example, a substrate made of a single metal such as aluminum, iron, copper, nickel and titanium, and an alloy containing these metals as a main component, for example, stainless steel. Examples thereof include iron alloys, titanium alloys, aluminum alloys represented by duralumin, and copper alloys represented by phosphor bronze.

When the metal substrate 2 made of aluminum is used, by setting the thickness to 66 μm or more, the rigidity required for the optical disk 1 can be obtained. In addition, it is more preferably set to 78 μm or more.

When the metal substrate 2 made of iron is used and the thickness thereof is 45 μm or more, the rigidity required for the optical disc 1 can be obtained. Moreover, it is more preferable that the thickness is 53 μm or more.

When a metal substrate 2 made of copper is used, and the thickness thereof is 53 μm or more, the rigidity required for the optical disc 1 can be obtained. Further, it is more preferable that the thickness is 64 μm or more.

When a metal substrate 2 made of nickel is used and the thickness thereof is 44 μm or more, the rigidity required for the optical disc 1 can be obtained. Moreover, it is more preferable that the thickness is 53 μm or more.

When the metal substrate 2 made of titanium is used, the rigidity required for the optical disc 1 can be obtained by setting the thickness to 55 μm or more. Further, it is more preferably 66 μm or more.

Further, as the metal substrate 2, Fe, Cr and N are used.
When stainless steel composed of i is used, the rigidity required for the optical disc 1 can be obtained by setting the thickness to 43 μm or more. Also, more preferably,
It is to be 50 μm or more.

As the metal substrate 2, Ti, Al and V are used.
When a titanium alloy composed of and is used, the rigidity required for the optical disc 1 can be obtained by setting the thickness to 51 μm or more. Also, more preferably,
It is to be 60 μm or more.

As the metal substrate 2, Al, Cu and M are used.
When duralumin composed of g is used, the rigidity required for the optical disc 1 can be obtained by setting the thickness to be 65 μm or more. Also, more preferably,
It is to be 77 μm or more.

As the metal substrate, Cu, Sn and P are used.
When phosphor bronze consisting of and is used, the thickness is
By setting the thickness to 55 μm or more, the rigidity required for the optical disc 1 can be obtained. Also, more preferably, 66
It is to be at least μm.

Resin layer 3 formed on the metal substrate 2
The layer thickness of 3 ′ is preferably 1 μm or more and 150 μm or less. The fine irregularities on the surface of the metal substrate 2 are
The resin layer 3.3 'is covered with the resin layer 3.3'.
The concave-convex pit pattern and / or the concave-convex guide groove pattern on the surface of the transparent stamper 7 having no concave-convex defects will be transferred to the surface of the resin layer. When the thickness is reduced, it becomes impossible to cover the fine irregularities on the surface of the metal substrate 2 with the resin layers 3 and 3 ', and the recording / reproduction error due to the irregularities increases. Further, if the layer thickness of the resin layer 3.3 ′ is larger than 150 μm, it takes a long time to cure the resin layer 3.3 ′, and the process time for manufacturing the optical disc becomes long, and This leads to an increase in cost, leads to an increase in the total plate thickness of the optical disc 1, and prevents the optical disc 1 from becoming thinner.

Recording medium layer 4 formed on the resin layer 3
As the recording medium, a rewritable phase change recording medium, a magneto-optical recording medium, or a write-once type dye recording medium can be used. Further, as the metal reflection layer 4 ′ formed on the resin layer 3 ′ having only the concave-convex pit pattern formed on the surface of the ROM type, an AlTi alloy (Al
₉₀ Ti ₁₀ ) can be used.

FIGS. 7 and 8 are enlarged cross-sectional views of the optical disc 1 when a phase change recording medium and a magneto-optical recording medium are used as the recording medium of the recording medium layer 4, respectively.

In the optical disc 1 using the phase change recording medium shown in FIG. 7, the resin layer 3 having the guide groove (concavo-convex guide groove pattern) 9 is formed on the metal substrate 2 by the 2P method, and then the recording medium layer 4 is formed. As the Al reflection film 11, ZnS-SiO ₂
The interference layer 12, the SiN protective layer 13, the GeSbTe phase change recording layer 14, the SiN protective layer 15, and the ZnS—SiO ₂ interference layer 16 are sequentially formed by sputtering, and further, the light transmitting protective layer 5 made of an ultraviolet curable resin is formed. It has been configured.

The optical disc 1 using the magneto-optical recording medium shown in FIG. 8 is capable of magnetic super-resolution reproduction after the resin layer 3 having the guide groove 9 is formed on the metal substrate 2 by the 2P method. As the recording medium layer 4, AgTi heat dissipation layer 17, Al
N protective layer 18, TbFeCo recording layer 19, Al nonmagnetic intermediate layer 20, GdFeCo reproducing layer 21, AlN interference layer 22.
Are sequentially formed by sputtering, and a transparent protective layer 5 made of an ultraviolet curable resin is further formed.

The light-transmissive protective layer 5 for protecting the recording medium layer 4 is irradiated with light for recording from the light-transmissive protective layer 5 side, and therefore it is necessary that at least light can be transmitted. is there. As the material of the light transmitting protective layer 5, a resin layer such as a resin sheet adhesive layer can be used in addition to the ultraviolet curable resin layer. When the light-transmitting protective layer 5 is formed by adhering a resin sheet, the thickness of the resin sheet can be controlled with high precision, so that the light-condensing characteristics on the recording medium layer 4 or the metal reflective layer 4 ′ can be improved. It becomes possible to make it good.

On the surface of the light-transmitting protective layer 5, a thin film capable of transmitting light and having high hardness, for example, 2 nm to 10 nm is used.
By forming a SiC thin film with a thickness of nm, it is possible to suppress an increase in errors due to the occurrence of scratches on the light incident surface of the optical disc 1.

The layer thickness of the light-transmitting protective layer 5 is 2 μm to
It is desirable to set it in the range of 150 μm. When the layer thickness of the light-transmitting protective layer 5 is less than 2 μm, the light-transmitting protective layer 5 is
Since the diameter of the light beam spot on the light incident surface becomes smaller, the dust adhering to the light-transmitting protective layer 5 causes a recording / reproducing error, which has a significant adverse effect on the replaceability of the optical disc 1. Further, the layer thickness of the light-transmitting protective layer 5 is 150 μm.
If the thickness is made thicker, the light-transmitting protective layer 5 may be hardened.
It takes a long time, the process time for manufacturing the optical disc becomes long, the cost of the optical disc increases, and the total plate thickness of the optical disc 1 increases, which prevents the optical disc 1 from being thin.

In a conventional optical disc such as an MD, a light beam passes through a transparent substrate (= disc substrate) having a thickness of 1.2 mm and is focused on a recording medium layer. Although the shape of the focused spot was deformed and the recording / reproducing characteristics were deteriorated, in the optical disc 1, the light beam is 2 μm to 150 μm.
Since the light passes through the extremely thin light-transmitting protective layer 5 and is condensed on the recording medium layer 4, stable recording and reproduction with little change in the condensed spot shape are realized with almost no coma aberration. be able to.

The thickness of the light-transmitting protective layer 5 increases the dustproof effect of the optical disc 1 when the optical disc 1 is inserted into an optical disc cartridge case (hereinafter referred to as a cartridge case) to improve the dustproof effect of the optical disc device. It can be made even thinner by increasing the error correction capability.

Furthermore, an optical disc having a structure not using the light-transmitting protective layer 5 and a thin film capable of transmitting light and having high hardness, for example, 2 nm to
It is also possible to form a SiC thin film having a thickness of 10 nm.

Next, a description will be given of a double-sided type optical disc 1'in which the recording medium layer 4 or the metal reflection layer 4'is formed on both front and back surfaces of the metal substrate 2. FIG. 9 is a partial cross-sectional view of the optical disc 1 '.

A double-sided optical disk 1'of a type capable of recording and reproducing comprises a metal substrate 2 and a resin layer 3 having an uneven pit pattern and / or an uneven guide groove pattern formed on both front and back surfaces of the metal substrate 2. 3, recording medium layers 4 and 4 respectively formed on the resin layers 3 and 3, and the recording medium layer 4
The light-transmitting protective layers 5 and 5 for protecting 4 respectively. On the other hand, a ROM-type double-sided optical disc 1 ′ that is used only for reproduction includes a metal substrate 2, resin layers 3 ′ and 3 ′ having concave and convex pit patterns formed on both front and back surfaces of the metal substrate 2, and the resin. A metal reflective layer 4 ', 4'formed on each of the layers 3', 3 ', and a light-transmissive protective layer 5, 5 for protecting the metal reflective layer 4', 4 ', respectively. There is. In any type of optical disc 1 ', an optical disc 1'including all thin layers from the metal substrate 2 to the light-transmitting protective layer 5 formed thereon.
Has a total thickness of 0.3 mm or less.

FIG. 10 is a diagram showing a method of forming the above-mentioned double-sided type optical disc 1'called the 2P method. The resin layer 3 (or the resin layer 3 ') on both surfaces of the metal substrate 2
Of the transparent stamper 7 · 7 (or the transparent stamper 7 ′ · 7 ′ having two concave / convex pit patterns) having the concave / convex pit pattern and / or the concave / convex guide groove pattern after applying the ultraviolet curable resin 3a The metal substrate 2 coated with the ultraviolet curable resin 3a is placed in close contact therewith, and ultraviolet rays 8 are respectively applied from both transparent stampers 7 (7 ', 7') side.
Is irradiated to cure the ultraviolet curable resin 3a applied on both sides of the metal substrate 2. After that, the transparent stamper 7.7
By peeling the metal substrate 2 and the cured ultraviolet curable resin 3a from (7 ′ · 7 ′), the resin layer 3 (or the resin layer 3 having an uneven pit pattern and / or an uneven guide groove pattern on both sides of the metal substrate 2 (or A disk substrate is formed on which the resin layer 3 ') having an uneven pit pattern is formed. By forming the recording medium layer 4 (or the reflective metal layer 4 ′) and the light-transmitting protective layer 5 on both sides of the optical disc substrate, a double-sided type optical disc 1 ′ can be manufactured.

Next, an optical disk device capable of recording / reproducing information on / from the optical disk 1 (1 ') will be described with reference to FIGS.

FIG. 11 shows a schematic diagram of an optical disk device. This optical disc apparatus handles a read-only ROM type optical disc 1 (1 ′) and a rewritable optical disc 1 (1 ′) using a phase change recording medium as a recording medium of the recording medium layer 4. FIG. 12 is a schematic diagram of the light emitting / receiving element portion in FIG.

The optical disc 1 (1 ') has a center hub 2
It is fixed to the spider 24 via 3 and is rotationally driven. In the radial direction of the optical disc 1 (1 '), an optical pickup 32 is arranged so as to be movable by a driving means (not shown). The optical pickup 32 includes a light emitting / receiving element portion 29 having a light emitting element 28 for recording / reproducing, a control light receiving element 27 for tracking and focusing, and a reproduction signal detecting light receiving element 26, and a light beam 30. A rising mirror 32 that leads to the condensing means 31 and 2
It is composed of a condensing means 31 supported by an axial actuator 33 so as to be drivable in the focus direction and the track direction.

In the light emitting / receiving element portion 29, the light beam emitted from the light emitting element 28 is collimated by the collimator lens and then reflected by the first beam splitter 34 to be guided to the rising mirror 32. Optical disc 1
The light is focused on the recording medium layer 4 (or the metal reflection layer 4 ′) of (1 ′). Further, the reflected light from the recording medium layer 4 (or the metal reflection layer 4 ′) of the optical disc 1 (1 ′) passes through the first beam splitter 34 and is split by the second beam splitter 35, so that one light The beam is focused on the control light receiving element 27 for tracking and focusing by the focusing lens, and the other light beam is focused on the reproduction signal detecting light receiving element 26 by the focusing lens.

Driving of the light emitting / receiving element section 29 and the biaxial actuator 33 is controlled by a signal processing circuit 36. The signal processing circuit 36 controls the power of the light emitting element 28 of the light emitting and receiving element section 29, and generates a reproduction signal of recorded information from the output from the reproduction signal detecting light receiving element 26. Further, the signal processing circuit 36 drives the biaxial actuator 33 to displace the light converging means 31 based on the output from the control light receiving element 27 of the light emitting and light receiving element section 29 together with the generation of the reproduction signal, and the light converging means 31 is displaced. Focusing is performed so that the light beam 30 that has passed through 31 enters from the light-transmitting protective layer 5 side and is focused on the recording medium layer 4, and at the same time, a focused spot is formed along the guide groove 9 on the resin layer 3. Makes it possible to perform recording and reproduction of information by performing tracking so as to move relatively.

In the case of the ROM type optical disc 1 (1 '), the light beam 30 is applied to the metal reflection layer 4'in the same manner as above.
Focusing is performed so that the light is focused, and tracking is performed so that the focused spot relatively moves along the pit (concave pit pattern) 10 on the resin layer 3 ′ of the optical disc 1 (1 ′). Is played.

In the above optical disk device, in order to reduce the diameter of the light beam spot, a semiconductor laser having a wavelength of 350 nm to 650 nm is used as the light emitting element, and the numerical aperture NA of the condensing means 31 is 0.70 to 1.00. Is desirable. In FIG. 11, the light collecting means 31 is composed of one objective lens. However, when the numerical aperture is increased to 0.80 or more, the light collecting means 31 is divided into two.
By constructing the objective lens group with one or more sheets, it is possible to easily manufacture a condensing means having a large numerical aperture.

FIG. 13 shows a schematic view of another optical disk device. This optical disk device is a read-only ROM
Type optical disc 1 and rewritable optical disc 1 using a phase change recording medium as the recording medium of the recording medium layer 4.
In addition, the present invention deals with a rewritable optical disc using a magneto-optical recording medium as the recording medium of the recording medium layer 4.

Since the main structure is the same as that of the optical disk device shown in FIG. 11, members having the same functions are designated by the same reference numerals and the description thereof will be omitted. The optical disk device shown in FIG. 13 is different from the optical disk device of FIG. 11 in that a magnetic head 4 for applying a recording magnetic field to the magneto-optical recording medium.
2 is provided.

When a magneto-optical recording medium is used as the recording medium of the recording medium layer 4, it is necessary to apply a recording magnetic field for recording, and it is integrated with the optical pickup 25 at a position facing the light converging means 31. A magnetic head 42 for applying a recording magnetic field, which is supported by a movable suspension 41, is arranged. The magnetic head 42 can be mounted on a slider so that the magnetic head 42 travels stably on the optical disc 1. The magnetic head 42 is arranged close to the metal substrate 2 side of the optical disc 1 (1 ′). Here, the magnetic head 42
Is arranged closer to the suspension 41 from the metal substrate side, but since the metal substrate 2 is thin, the magnetic field strength generated from the magnetic head 42 reaches the recording medium layer 4 without being greatly attenuated, A recording magnetic field of sufficient strength can be applied to the recording medium layer 4.

Further, the optical disc 1 (1 ') using the metal substrate 2 is housed in an optical disc cartridge case (hereinafter referred to as a cartridge case) to form an optical disc cartridge in order to protect the optical disc 1 from dust as described above. You can also

Next, referring to FIGS. 14 to 16, an optical disk cartridge in which the optical disk 1 (1 ′) is housed in a cartridge case, and an optical disk device capable of recording / reproducing information on / from the optical disk cartridge are described. explain.

FIG. 14 shows an optical disk cartridge 50 in which the optical disk 1 (1 ′) is housed in a cartridge case 37, and an optical disk device which handles the optical disk cartridge 50. FIG. 15 shows the cartridge case 3
7 shows a plan view of FIG.

The cartridge case 37 includes the spindle 2
4, a first opening 38 for fixing the optical disc 1 (1 ′) and a second opening 39 for exposing the condensing means 31 of the optical pickup 25 to the optical disc 1 (1 ′). It is provided on one side of the cartridge case 37. Although not particularly shown, when the optical disc is a double-sided type optical disc 1 ′, the first opening 38 and the second opening 39 are formed on both sides of the cartridge case 37, respectively.

Further, as shown in FIG. 15, a slide shutter 40 that can be opened and closed is provided in the first opening 38 and the second opening 39 of the cartridge case 37. When the optical disk cartridge 50 is mounted on the optical disk device, the slide shutter 40 is set to the first position.
The opening 38 and the second opening 39 are opened, and when the optical disk cartridge 50 is taken out from the optical disk device, the first opening 38 and the second opening 39 are closed. By providing the slide shutter 40, it becomes possible to prevent dust from adhering to the optical disc 1 (1 ′).

In the case of the optical disc 1 (1 ′), the layer thickness of the light-transmitting protective layer 5 through which the light beam 30 passes is 2 μm to.
The thickness is 150 μm, and dust adheres to the surface of the light-transmitting protective layer 5, whereby accurate recording / reproducing cannot be performed. Therefore, in the optical disc 1 (1 '),
It is preferable to prevent dust from adhering to the surface of the optical disc 1 by the optical disc cartridge case 37 having the slide shutter 40 that can be opened and closed.

As the material of the cartridge case 37,
Resins such as polycarbonate and metallic materials such as stainless steel and duralumin can be used.

When resin is selected as the material, it is necessary to have a certain thickness in order to obtain the rigidity required for the cartridge case 37. When the cartridge case 37 is made of resin, if the thickness of the cartridge case 37 is too thin, the rigidity of the cartridge case 37 decreases, and the cartridge case 37 cannot serve its original role of protecting the optical disc 1 (1 ′). For example, when loading or unloading the optical disk cartridge 50 with respect to the optical disk device, the cartridge case 3
7 is curved and comes into contact with the optical disc 1 (1 ′), causing a problem such as scratching the surface of the optical disc 1 (1 ′) or damaging the cartridge case 37 itself. For this reason, the plate thickness of the resin cartridge case 37 is preferably 0.8 mm or more.

FIG. 16 shows an optical disk cartridge 5 using a resin cartridge case 37 having a plate thickness of 0.8 mm.
0 shows a sectional view of 0. The total thickness of the optical disc 1 (1 ') is a, the plate thickness of the cartridge case 37 is c, and here = 0.8 mm. Optical disc 1
The distance required to prevent contact between (1 ′) and the cartridge case 37 is d, and d is at least 0.3.
mm is required.

Here, the total thickness of the optical disk cartridge 50 is the total thickness a of the optical disk 1 (1 ').
And twice the thickness c of the cartridge case 37, and the distance d
Of the total thickness (a + 2b + 2c = a + 2.
2 mm). Therefore, in order to realize an optical disk device having a thickness of 5 mm, the optical disk cartridge 5
It is necessary to set the thickness of 0 to 2.5 mm or less, that is, the total thickness of the optical disc 1 (1 ') is 0.3 mm.
It is necessary to set it to mm or less.

By setting the total thickness of the optical disc 1 (1 ') to 0.3 mm or less, even if the cartridge case 37 is formed of a resin that has been widely used in the past, an optical disc device having a thickness of 5 mm can be provided. It can be realized.

On the other hand, when a metal material having higher rigidity than resin is used as the material of the cartridge case 37,
Even if the wall thickness is reduced, the rigidity required for the cartridge case 37 can be obtained, and the optical disk cartridge 50, and thus the optical disk device, can be made even thinner.

FIG. 17 shows a metal cartridge case 3
7 is a sectional view of an optical disc cartridge 50 using No. 7. The total thickness of the optical disc 1 (1 ') is a, and the plate thickness of the cartridge case 37 is e. It has been confirmed that when stainless steel is used as the material of the cartridge case 37, e = 0.16 mm and the same rigidity as that of the 0.8 mm-thick polycarbonate resin cartridge case 37 can be realized. Optical disc 1 (1 ')
The distance required to prevent contact between the cartridge case 37 and the cartridge case 37 is d, and d must be at least 0.3 mm.

Here, the total thickness of the optical disk cartridge 50 is the total thickness a of the optical disk 1 (1 ').
And twice the thickness e of the cartridge case 37, and the distance d
Of the total thickness (a + 2b + 2e = a + 0.
92 mm). Therefore, if a is the same,
By using the disk cartridge 37 made of metal, it is possible to realize an optical disk cartridge which is thinner by 1.28 mm as compared with the case of using the one made of polycarbonate resin.

Optical disc cartridge case 3 made of metal
As 7, a metal other than stainless steel can be used. In particular, a thin and lightweight optical disk cartridge can be realized by using a light alloy such as duralumin or a titanium alloy.

The structure of the optical disk device shown in FIG. 14 which handles such an optical disk cartridge 50 is shown in FIG.
Since it is the same as the optical disk device shown in FIG. 1, the members having the same functions are designated by the same reference numerals and the description thereof will be omitted.

FIG. 18 shows the cartridge case 3
Reference numeral 7'denotes a magneto-optical recording type optical disc cartridge 50 'in which an optical disc 1 (1') using a magneto-optical recording medium is contained in a recording medium layer 4, and an optical disc device which handles the optical disc cartridge 50 '. .

When the recording medium layer 4 is the optical disc 1 (1 ') made of a magneto-optical recording medium, a recording magnetic field is required for recording, and as shown in FIG. The third opening 43 for arranging the magnetic head 42 for generating a magnetic field close to the metal substrate 2 side of the optical disc 1 (1 ′) is the second opening 39.
Is provided at a position opposite to. In this case, the slide shutter 40 that can be opened and closed includes the first opening 38 and the second opening 38.
It is desirable to be provided so as to cover the opening 39 and the third opening 43. Further, although not particularly shown, when the optical disk is a double-sided type optical disk 1 ', the first opening 38, the second opening 39, and the third opening 38 are provided.
The openings 43 are formed on both sides of the cartridge case 37 '. In this case, the cartridge case 3
The second opening 39 and the third opening formed on the same surface of 7'are also used, and as a result, the same configuration as the configuration in which the second opening 39 is provided on both surfaces of the cartridge case 37 shown in FIG. Become.

The structure of the optical disk device shown in FIG. 18 for handling such an optical disk cartridge 50 'is basically the same as that of the optical disk device shown in FIG. The reference numerals are attached and the description is omitted.

Further, the optical disk cartridge 50.
The thickness of 50 'is preferably 2.5 mm or less, and the optical disc 1 (1') using the metal substrate 2 is used.
In the above, the thickness of the optical disk cartridge 50/50 'can be 2.5 mm or less.

The present invention is intended to realize an optical disk 1 used in an optical disk device having a thickness of 5 mm or less that can be inserted into a card slot of a portable device such as a notebook computer.
As for the thickness 50 ', it is necessary to be insertable into an optical disk device having a thickness of 5 mm or less. Although there is an MD as an existing optical disc, the thickness of an optical disc device that handles the MD is about 10 mm.
The thickness of the cartridge is 5 mm. From this, by using the current mounting technology, it becomes possible to realize an optical disc device having a thickness approximately twice that of the optical disc cartridge.

Therefore, by setting the thickness of the optical disc cartridges 50 and 50 'to 2.5 mm or less, it is possible to realize an optical disc device having a thickness of 5 mm.

[0093]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 As the metal substrate 2 constituting the disk substrate, a substrate made of stainless steel (Fe ₇₆ Cr ₁₇ Ni ₇ ) having a diameter of 50 mm and a thickness of 37 μm (hereinafter, a metal substrate made of stainless steel is referred to as a stainless substrate). Using
A resin layer 3 ′ having a layer thickness of 10 μm having a concavo-convex pit pattern is formed on the stainless steel substrate 2 by the 2P method, and a metal reflection layer 4 ′ made of an Al ₉₀ Ti ₁₀ alloy is formed by sputtering.
After forming, the light-transmitting protective layer 5 has a layer thickness of 20 μm.
The ultraviolet curable resin layer of No. 1 was formed by a spin coating method to prepare a ROM type optical disc 1 having a diameter of 50 mm.
Similarly, by changing the thickness of the stainless steel substrate 2,
A plurality of ROM type optical disks 1 having a diameter of 50 mm were formed.

The metal substrate 2 has a diameter of 80 mm,
Made of stainless steel with a thickness of 37 μm (Fe ₇₆Cr₁₇Ni₇)of
Using a substrate and following the same procedure on the stainless steel substrate 2,
The resin layer 3 ′, the metal reflection layer 4 ′, and the light transmissive protective layer 5 are
ROM type optical disk 1 with a diameter of 80 mm
It was made. Similarly, the thickness of the stainless steel substrate 2 can be varied.
Changed, ROM type optical disk 1 with a diameter of 80 mm
A plurality of layers were formed.

The metal substrate 2 has a diameter of 130 mm.
And made of stainless steel with a thickness of 37 μm (Fe ₇₆ Cr ₁₇ N
i ₇ ), the resin layer 3 ′, the metal reflection layer 4 ′, and the light-transmitting protective layer 5 are formed on the stainless steel substrate 2 by the same procedure, and the ROM type optical disc 1 having a diameter of 130 mm is formed. Was produced. Similarly, various thicknesses of the stainless steel substrate 2 were changed to form a plurality of ROM type optical disks 1 having a diameter of 80 mm.

Regardless of the diameter size, the concavo-convex pit row in the metal reflection layer 4'has a track pitch of 0.3 μm.
A pit row having a pit diameter of 0.15 μm, a pit period of 0.3 μm, and a pit depth of 25 nm was spirally formed at m. In addition, the total thickness of each optical disc 1 was approximately the thickness of the stainless steel substrate 2 plus the thickness of the resin layer 3 ′ and the light-transmitting protective film 5, regardless of the diameter size.

After the center hub 23 (see FIG. 11) is adhered and fixed to each of the optical discs 1 thus formed, as shown in FIG.
It was mounted on the optical disk device shown in (1) and rotated at 2000 rpm to measure the focus error amount.

In the optical disc 1 having a diameter of 50 mm,
The focus error amount was measured at an inner peripheral position having a diameter of 22 mm (11 mm from the center) and an outer peripheral position having a diameter of 44 mm (22 mm from the center). On the other hand, in the optical disc 1 having a diameter of 80 mm, the diameter 37
The focus error amount was measured at an inner peripheral position of mm (18.5 mm from the center) and an outer peripheral position of 74 mm in diameter (37 mm from the center). For an optical disc 1 with a diameter of 130 mm, the diameter is 30 mm
Inner circumference position (15 mm from center) and diameter 1
The focus error amount was measured at the outer peripheral position which was a position of 20 mm (60 mm from the center). Further, a semiconductor laser having a wavelength of 405 nm was used as the issuing element 28 of the optical disk device used here, and a second group objective lens having an NA of 0.85 was used as the focusing means 31. Also,
After focusing is performed, tracking is performed on the spirally formed pit row and the laser light is adjusted to 0.
The above pit train was reproduced by continuously irradiating with a power of 5 mW. The output from the reproduction signal detecting light receiving element 26 was evaluated by a spectrum analyzer.

Table 1 shows the measurement result of the focus error amount of the optical disc 1 having a diameter of 50 mm, and Table 2 shows the measurement result of the focus error amount of the optical disc 1 having a diameter of 80 mm.
Table 3 shows the measurement results of the focus error amount of the 30 mm optical disc 1.

[0101]

[Table 1]

[0102]

[Table 2]

[0103]

[Table 3]

From Table 1, in the case of the optical disc 1 having a diameter of 50 mm, the focus error in the focus direction is ± 0.2 μ when the thickness of the stainless steel substrate 2 is 43 μm or more.
It becomes m or less, and focusing is possible. When there is a focus error of ± 0.2 μm or more in the focus direction, the expansion of the light beam spot diameter becomes remarkable and focusing becomes impossible. Therefore, the allowable value of the focus error amount is set to less than ± 0.2 μm. It was also confirmed that the uneven pit information of the ROM type optical disc 1 can be accurately reproduced within the range of the plate thickness. Specifically, as a result of evaluating the output from the reproduction signal detecting light receiving element 26 with a spectrum analyzer, it was confirmed that a signal-to-noise ratio of 49 dB was obtained, and it was found that a practical reproduction can be realized.

Also, from Table 2, in the case of the optical disc 1 having a diameter of 80 mm, the stainless steel substrate 2 has a thickness of 43 as well.
Under the condition of μm or more, the focus error in the focus direction is less than ± 0.2 μm, which shows that the focusing is good. It was also confirmed that the uneven pit information of the ROM type optical disc 1 can be accurately reproduced within the range of the plate thickness. Actually, the concave-convex pit information could be accurately reproduced for the optical disc 1 in which the thickness of the stainless steel substrate 2 was within the range.

Further, from Table 3, in the case of the optical disc 1 having a diameter of 130 mm, the thickness of the stainless steel substrate 2 is 4 as well.
Under the condition of 3 μm or more, the focus error in the focus direction is less than ± 0.2 μm, which shows that the focusing is good. Also, within this range of thickness, ROM
It was confirmed that the concave-convex pit information of the optical disc 1 of the type can be accurately reproduced. Actually, the concave-convex pit information could be accurately reproduced for the optical disc 1 in which the thickness of the stainless steel substrate 2 was within the range.

Here, regardless of the diameter size, the reason why the focus error amount exceeds the allowable value when the thickness of the stainless steel substrate 2 is less than 43 μm is that the rigidity of the stainless steel substrate 2 becomes too low and the optical disc 1 is used. This is because the lowering of the rigidity causes the optical disc 1 to move up and down (fluttering), and the stable rotation cannot be achieved.

From these results, it can be said that when a metal substrate is used as the disk substrate, a focus error amount of less than 0.2 μm can be realized and good focusing can be achieved by setting the thickness of the stainless steel substrate 2 to 43 μm or more. .

Therefore, next, the rigidity is determined when the thickness of the stainless steel substrate 2 is 43 μm or more.

Rigidity δ of stainless steel substrate 2 (kgf · m
m) is the Young's modulus E (kgf / mm ² ) of stainless steel,
It can be calculated by the following equation (1) using the Poisson's ratio v and the thickness h (mm).

Δ = E · h ³ (1-v ² ) / 12 (1) In the formula (1), Young's modulus of stainless steel E = 25000 kg
Substituting f / mm ² and Poisson's ratio v = 0.29 of stainless steel, the rigidity δ of the stainless steel substrate 2 is calculated as follows.
The graph of FIG. 19 was obtained as a function of thickness.

From the graph, the stainless steel substrate 2 has a thickness of 4
It can be seen that the rigidity δ of 3 μm or more is 0.15 kgf · mm or more.

From the above, in the case of the optical disc 1 using the metal substrate as the disc substrate, the rigidity of the metal substrate 2 is 0.1.
If it is 5 kgf · mm or more, it can be said that stable focusing becomes possible and the concave and convex pit information of the ROM type optical disc 1 can be reproduced.

Further, more specifically, the focus error amount is ± less than ± 0.2 μm as described above.
It is more preferable that the thickness is 0.1 μm or less. By setting the focus error amount to ± 0.1 μm or less, it is possible to reduce the drive amount of the focusing means 31 required for focusing, and it is possible to make the biaxial actuator 33 that drives the focusing means 31 thin. It will be possible.

From Tables 1, 2 and 3, it can be seen from Tables 1, 2 and 3 that the thickness of the stainless steel substrate 2 with the focus error amount of ± 0.1 μm or less is 50 μm or more. From this,
It can be said that it is more desirable to set the rigidity of the metal substrate 2 to 0.24 kgf · mm or more in the optical disc 1 having a diameter of at least 50 to 130 mm.

In the above optical disc 1, the metal reflection layer 4'has a thickness of about several tens of nanometers, which is significantly smaller than the thickness of the metal substrate 2 and has almost no influence on the rigidity of the optical disc 1. Conceivable. Further, the resin layer 3 ′ formed by the 2P method and the light-transmitting protective layer 5 formed of the ultraviolet curable resin formed by the spin coating method have a Young's modulus of 230 kgf · mm ^2, which is higher than that of the metal substrate 2. It is a value that is two orders of magnitude smaller, and the influence on the rigidity of the optical disc 1 is extremely small and can be ignored. Therefore, here, the rigidity of the metal substrate 2 is treated as the rigidity of the optical disc 1, ignoring the existence of the metal reflection layer 4 ′, the resin layer 3 ′, and the light-transmitting protective layer 5.

Next, the optical disc 1 is inserted into the cartridge case 37 to form an optical disc cartridge 50,
As a result of similarly investigating whether or not the focusing operation is possible by using the optical disk device shown in FIG. 14, when the plate thickness of the stainless steel substrate 2 is 43 μm or more, in the focusing direction as in the case where the optical cartridge case 37 is not used. It was confirmed that the focus error of No. 2 was ± 0.2 μm or less, stable focusing was possible, and the uneven pit information of the ROM type optical disc 1 could be reproduced.

Here, a polycarbonate resin is used for the cartridge case 37. The plate thickness,
Since the thickness is 0.8 mm, when loading or unloading the optical disk cartridge 50 with respect to the optical disk device, the cartridge case 37 is curved, contacts the optical disk 1, and scratches the surface of the optical disk 1. I didn't. Moreover, the cartridge case 37 itself was not damaged.

When a cartridge case 37 made of polycarbonate resin having a plate thickness of 0.8 mm is used, in order to prevent contact between the optical disk 1 and the cartridge case 37, a space between the optical disk 1 and the inner wall surface of the cartridge case 37 is provided. , At least 0.3 mm was required. From these facts, in order to realize an optical disc device having a thickness of 5 mm, the thickness of the optical disc cartridge 50 should be 2.5 m.
It has been confirmed that the thickness is required to be m or less, and the total thickness of the optical disc 1 is required to be 0.3 mm or less.

Further, subsequently, the above diameters of 50 mm and 80 m
For each of the three types of optical disks 1 of m and 130 mm, the focus error amount at the inner peripheral position and the outer peripheral position when the number of rotations of the optical disk 1 was changed at 43 μm, which is the lower limit of the thickness of the stainless steel substrate 2 that enables good focusing. To see how it changes. The inner peripheral position and the outer peripheral position where the focus error amount is measured in the optical disc 1 of each size are the same as those in the first embodiment.

Table 4 shows the result of measuring the focus error amount.
~ Shown in Table 6.

[0122]

[Table 4]

[0123]

[Table 5]

[0124]

[Table 6]

Table 4 shows the measurement results of the stainless steel substrate 2 having a diameter of 50 mm, Table 5 shows the measurement results of the stainless steel substrate 2 having a diameter of 80 mm, and Table 6 shows the stainless steel substrate 2 having a diameter of 130 mm.
Is the measurement result.

As can be seen from Tables 3 to 6, it was confirmed that the focus error amount did not change remarkably even if the rotation speed (rotation speed) was changed in all diameter sizes.

[Embodiment 2] A metal substrate 2 having a diameter of 80
mm, 50 μm thick stainless steel (Fe ₇₆ Cr ₁₇ N
i ₇ ) Using the substrate 2, a layer thickness 10 having a spiral guide groove 9 (see FIG. 5) having a track pitch of 0.3 μm and a width of 0.15 μm and a depth of 20 nm on the stainless steel substrate 2.
The resin layer 3 made of a UV curable resin layer having a thickness of μm was formed by the 2P method. Next, as the recording medium layer 4, a film thickness of 100 n
m Al reflective film 11, 10 nm thick ZnS-SiO2
Interference layer 12, SiN protective layer 13 having a film thickness of 4 nm, film thickness 20
GeSbTe phase change recording layer 14 with a thickness of 4 nm
The iN protective layer 15 and the ZnS-SiO2 interference layer 16 having a film thickness of 40 nm were sequentially formed by sputtering to form a phase change recording medium layer (see FIG. 7). Further, an ultraviolet curable resin was applied by a spin coating method to form a light-transmitting protective layer 5 made of an ultraviolet curable resin having a layer thickness of 20 μm, and an optical disc 1 having a diameter of 50 mm was prepared using a rewritable phase change recording material. . The total thickness of the optical disc 1 was about 80 μm.

As shown in FIG. 14, the optical disk 1 was put in a cartridge case 37 to form an optical disk cartridge 50, and the recording / reproducing characteristics were examined using an optical disk device. Here, the light emitting element 28 of the optical disk device
Is a semiconductor laser having a wavelength of 405 nm, and the condensing unit 31 is a second group objective lens having a numerical aperture of 0.90. I went.

As the cartridge case 37, one made of polycarbonate resin having a plate thickness of 0.8 mm was used.
In the optical disc cartridge 50, the total thickness of the optical disc 1 was as thin as 80 μm, so that the thickness of the optical disc cartridge 50 could be made as thin as about 2.28 mm. By the way, the conventional optical disc MD
The optical disc has a thickness of 1.2 mm and the optical disc cartridge has a thickness of 5.0 mm.

Here, the rotation speed of the optical disk 1 is set to 2000.
In rpm, the diameter of the optical disk 1 is 60 mm (radius 30
(mm) position, the focus error during focusing is 0.08 μm or less. As a result, a stable focusing operation can be achieved in the optical disc device shown in FIG. 14 using the conventional biaxial actuator 33. It was possible.

After focusing, the guide groove 9 is tracked, and a laser beam is irradiated with an optical pulse at a recording power of 5 mW to make the mark length 0.
Recording marks having a thickness of 12 μm and a mark pitch of 0.24 μm were formed, and then laser light was continuously irradiated with a reproducing power of 0.5 mW to reproduce the recorded information. As a result of evaluating the output from the reproduction signal detecting light receiving element 26 with a spectrum analyzer, it was confirmed that a signal-to-noise ratio of 46 dB was obtained, and practical recording and reproduction were realized in the optical disc 1 and the optical disc device of the present invention. I knew I could do it.

Although the thickness of the stainless steel substrate 2 is 50 μm here, as described in Example 1, when the thickness of the stainless steel substrate 2 is 43 μm or more, stable focusing becomes possible and stable. It was confirmed that recording and playback could be realized.

[Embodiment 3] A metal substrate 2 having a diameter of 80
mm, 50 μm thick stainless steel (Fe ₇₆ Cr ₁₇ N
i ₇ ) Using the substrate 2, a layer thickness 10 having a spiral guide groove 9 (see FIG. 5) having a track pitch of 0.3 μm and a width of 0.15 μm and a depth of 20 nm on the stainless steel substrate 2.
The resin layer 3 made of a UV curable resin layer having a thickness of μm was formed by the 2P method. Next, as the recording medium layer 4, the film thickness is 20 nm.
AgTi heat dissipation layer 17 and AlN protective layer 1 with a thickness of 10 nm
8, TbFeCo recording layer 19 having a film thickness of 40 nm, film thickness 5 n
m Al non-magnetic intermediate layer 20, 25 nm thick GdFeC
A reproducing layer 21 and an AlN interference layer 22 having a thickness of 40 nm were sequentially formed by sputtering to form a magneto-optical recording medium layer capable of magnetic super-resolution reproduction (see FIG. 8). further,
UV curable resin is applied by spin coating to give a layer thickness of 2
The optical transparent protective layer 5 made of 0 μm ultraviolet curable resin was formed, and an optical disc 1 having a diameter of 50 mm was prepared using a magneto-optical recording medium capable of rewriting and magnetic super-resolution reproduction. The total thickness of the optical disc 1 was about 80 μm.

As shown in FIG. 18, the optical disc 1 was placed in a cartridge case 37 ', and the recording / reproducing characteristics were examined using an optical disc device. Here, a semiconductor laser having a wavelength of 405 nm is used as the light emitting element 28 of the optical disk device, and the converging means 31 has a numerical aperture of 0.
Recording and reproduction were carried out by converging and irradiating a light beam from the side of the light-transmitting protective layer 5 using a 90-second objective lens.

As the cartridge case 37, one made of polycarbonate resin having a plate thickness of 0.8 mm was used.
In the optical disc cartridge 50, the total thickness of the optical disc 1 was as thin as 80 μm, so that the thickness of the optical disc cartridge 50 could be made as thin as about 2.28 mm. By the way, the conventional optical disc MD
The optical disc has a thickness of 1.2 mm and the optical disc cartridge has a thickness of 5.0 mm.

Here, the rotation speed of the optical disk 1 is set to 2000.
As a result of investigating whether or not the focusing operation is possible at a position where the radius is 30 mm as the rpm, the focus error at the time of focusing is 0.09.
It was less than μm, and stable focusing operation was possible with the optical disk device shown in FIG. 18 using the conventional biaxial actuator 33.

After focusing, the guide groove 9 is tracked to irradiate a laser beam with an optical pulse at a recording power of 7 mW and the magnetic head 42.
The optical disc 1 produces a modulated magnetic field with a maximum strength of 16 kA / m.
When applied to the recording medium surface of, the mark length is 0.08μ
A recording mark having a m and a mark pitch of 0.16 μm was formed. Then, laser light was continuously irradiated with a reproducing power of 1.0 mW to reproduce the recorded information. As a result of evaluating the output from the reproduction signal detecting light receiving element 26 with a spectrum analyzer, it was confirmed that a signal-to-noise ratio of 47 dB was obtained, and practical recording and reproduction were realized in the optical disc 1 and the optical disc apparatus of the present invention. I knew I could do it.

Although the thickness of the stainless steel substrate 2 is 50 μm here, as described in Example 1, when the thickness of the stainless steel substrate 2 is 43 μm or more, stable focusing becomes possible and stable. It was confirmed that recording and playback could be realized.

[Embodiment 4] A metal substrate 2 having a diameter of 80
mm, 50 μm thick stainless steel (Fe ₇₆ Cr ₁₇ N
i ₇ ) A resin layer comprising a substrate 2 and an ultraviolet curable resin layer formed on the stainless steel substrate 2 with 0.30 μm pitch spiral pits having a track pitch of 0.3 μm and a width of 0.15 μm and a depth of 20 nm. 3 was formed by the 2P method. Next, as the metal reflective layer 4, Al having a film thickness of 50 nm is used.
_{A 0.9} Ti _0.1 metal reflective film was formed by double-sided sputtering. Further, an ultraviolet curable resin is applied on each of the metal reflection layers 4 formed on both sides by a spin coating method to form a light transmissive protective layer 5 having a layer thickness of 20 μm, and the ROM
A double-sided optical disc 1'of a type (see FIG. 9) was produced.
The total thickness of the optical disc 1'is about 110 μm.
Met.

Using the optical disk device shown in FIG. 14, the optical disk 1'was similarly examined for the focusing operation. Here, the cartridge case 37 into which the optical disc 1 ′ of the present embodiment is inserted needs to reproduce information from both sides, and the second opening 39 is provided on both sides of the cartridge case 37.

The rotation speed of the optical disk 1'is 2000 rpm.
As a result, as a result of investigating whether or not the focusing operation is possible at the position of the radius 30 mm of the optical disc 1 ′,
Focus error during focusing is 0.05 μm
This is the following, and stable focusing operation was possible with the optical disk device shown in FIG. 14 using the conventional biaxial actuator 33.

The total thickness of the optical disc 1'is 110 μm.
Since the optical disc cartridge 50 is as thin as m, the thickness of the optical disc cartridge 50 is 2.31 mm, which is thinner than the conventional optical disc cartridge. Incidentally, MD, which is a conventional optical disc, has an optical disc thickness of 1.2 mm and an optical disc cartridge case thickness of 5.0 mm, which is a double-sided type that is thinner than a conventional single-sided type optical disc cartridge. It was possible to realize the optical disk cartridge 50.

Here, the single-sided type optical disc 1 shown in Example 1 manufactured by using the stainless steel substrate 2 having the same thickness.
There was a focus error of 0.08 .mu.m during the focusing operation, but in the optical disc 1'of the present embodiment of the double-sided type, the focus error during focusing is as small as 0.05 .mu.m or less. This is because the resin layer 3 ′, the metal reflection layer 4 ′, and the light-transmitting protective layer 5 are symmetrically formed on both surfaces of the metal substrate 2.
It is considered that the stresses of the layers formed on both surfaces of the metal substrate 2 are balanced with respect to the metal substrate 2.

As described above, in the double-sided type optical disc 1'of the present embodiment, the vertical movement in the focus direction is suppressed to be lower than that of the first embodiment, and stable focusing and tracking are realized. Better reproduction characteristics were obtained.

Although the thickness of the stainless steel substrate 2 is 50 μm here, as described in Example 1, when the thickness of the stainless steel substrate 2 is 43 μm or more, stable focusing becomes possible and stable. It was confirmed that recording and playback could be realized.

Further, as shown in Examples 2 and 3, as the recording medium layer 4 instead of the metal reflection layer 4 ', the recordable and reproducible optical disc 1 is the double-sided type optical disc 1'as in the present embodiment. It was confirmed that, by setting the above, the vertical movement of the optical disc 1 in the focus direction is suppressed, and more stable recording / reproducing is realized.

[Embodiment 5] The metal substrate 2 has a diameter of 50.
An aluminum substrate having a thickness of 80 μm and a thickness of 80 μm (hereinafter referred to as an aluminum substrate) is used.
Track pitch 0.3 μm, diameter 0.15 μm depth 2
A resin layer 3 ′ made of an ultraviolet curable resin having a layer thickness of 10 μm, in which spiral pit rows of 0 nm were formed at a pitch of 0.30 μm, was formed by the 2P method shown in FIG. Next, as the metal reflection layer 4 ', an Al _0.9 Ti _0.1 metal reflection film having a film thickness of 50 nm was formed by sputtering. Further, an ultraviolet curable resin is applied by a spin coating method to obtain a layer thickness of 20
A light-transmitting protective layer 5 made of a UV curable resin having a thickness of μm was formed on the metal reflective layer 4 to prepare the ROM type optical disk 1 shown in FIG. The total thickness of the optical disc 1 was about 110 μm.

The optical disk 1 is used in the cartridge case 3
No. 7, and the reproduction characteristics were investigated in the same manner as in Example 1 by using the optical disk device shown in FIG.

As the cartridge case 37, one made of polycarbonate resin having a plate thickness of 0.8 mm was used. In the above optical disc cartridge 50, the total thickness of the optical disc 1 was as thin as 110 μm, so that the thickness of the optical disc cartridge 50 could be made as thin as approximately 2.31 mm. Incidentally, in the MD which is a conventional optical disc, the thickness of the optical disc is 1.2 mm and the thickness of the optical disc cartridge is 5.0 mm.

Then, in the same manner as in Example 1, a light beam was condensed and irradiated from the side of the light-transmitting protective layer 5 and was rotationally driven at 2000 rpm, and whether or not the focusing operation was possible was examined at the position of the radius 30 mm of the optical disk 1. result,
Focus error during focusing is 0.09μm
This is the following, and stable focusing operation was possible with the optical disk device shown in FIG. 14 using the conventional biaxial actuator 33.

After focusing, the pit row formed in a spiral shape is tracked, and laser light is continuously irradiated with a power of 0.5 mW.
The above pit train was reproduced. As a result of evaluating the output from the reproduction signal detecting light receiving element 26 with a spectrum analyzer, it was confirmed that a signal-to-noise ratio of 48 dB was obtained, and practical reproduction can be realized in the optical disc 1 and the optical disc device thereof of the present invention. I understood.

Next, Young's modulus of aluminum E = 703
0 kgf / mm ² , Poisson's ratio of aluminum v = 0.
Substituting 345 into the equation (1), the rigidity δ of the aluminum substrate 2 was obtained as a function of the thickness of the aluminum substrate 2 to obtain the graph of FIG. From the graph, the rigidity δ is 0.15 kgf
・ The thickness of the aluminum substrate 2 which is not less than mm is 66μ.
It can be seen that it is m or more.

From the above, when the aluminum substrate 2 is used as the metal substrate 2, by setting the thickness to 66 μm or more, stable focusing becomes possible,
It can be said that the concave-convex pit information of the ROM type optical disc 1 can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, it was confirmed that when the aluminum substrate 2 was used as the metal substrate 2, by setting the thickness to 66 μm or more, stable focusing becomes possible and stable recording and reproduction can be realized.

Further, the focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is within the range of satisfying gf · mm, when the aluminum substrate 2 is used as the metal substrate 2 as seen from the graph of FIG. 20, the thickness thereof is more preferably set to 78 μm or more.

Example 6 Instead of the aluminum substrate 2 described in Example 5, a metal substrate 2 made of iron (hereinafter referred to as iron substrate 2) was used. The optical disc 1 is manufactured, inserted into the cartridge case 37, and the reproduction characteristics of the optical disc device shown in FIG. 14 are examined in the same manner as in Example 1. As a result, the same result as in Example 5 is obtained. It was

Also, the rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the iron substrate 2 of 5 kgf · mm or more, the Young's modulus of iron E = 21600 kgf / mm ² and the Poisson's ratio of iron v = 0.30 are substituted into the equation (1) to obtain the iron substrate 2
21 was obtained as a function of the thickness of the iron substrate 2 by the rigidity δ of. From the graph, the rigidity δ is 0.15 kgf · m
It can be seen that the thickness of the iron substrate 2 having a thickness of m or more is 45 μm or more.

From the above, in the case of the optical disc 1 using the iron substrate 2 as the metal substrate 2 constituting the disc substrate,
By setting the thickness to 45 μm or more, stable focusing becomes possible, and it can be said that the concave and convex pit information of the ROM type optical disc 1 can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, when the iron substrate 2 is used as the metal substrate 2, by setting the thickness to 45 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG. 21,
When the iron substrate 2 is used as the metal substrate 2, its thickness is 5
More preferably, it is 3 μm or more.

[Embodiment 7] Instead of the aluminum substrate 2 described in Embodiment 5, a metal substrate 2 made of copper (hereinafter referred to as copper substrate 2) is used. The optical disc 1 is manufactured, inserted into the cartridge case 37, and the reproduction characteristics of the optical disc device shown in FIG. 14 are examined in the same manner as in Example 1. As a result, the same result as in Example 5 is obtained. It was

Further, the rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the copper substrate 2 of 5 kgf · mm or more, the Young's modulus of copper E = 13000 kgf / mm ² and the Poisson's ratio of copper v = 0.343 are substituted into the equation (1) to determine the rigidity δ of the copper substrate 2. 22 was obtained as a function of the thickness of the copper substrate 2. From the graph, the rigidity δ is 0.15 kgf
It can be seen that the thickness of the copper substrate 2 that is equal to or greater than mm is 53 μm or greater.

From the above, in the case of the optical disc 1 using the copper substrate 2 as the metal substrate 2 constituting the disc substrate,
It can be said that by setting the thickness to 53 μm or more, stable focusing becomes possible and the concave and convex pit information of the ROM type optical disc 1 can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, when the copper substrate 2 is used as the metal substrate 2, by setting the thickness to 53 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG.
When the copper substrate 2 is used as the metal substrate 2, its thickness is 6
More preferably, it is 4 μm or more.

[Embodiment 8] Instead of the aluminum substrate 2 described in Embodiment 5, a metal substrate 2 made of nickel (hereinafter referred to as nickel substrate 2) is used. The optical disc 1 is formed and is inserted into the cartridge case 37. Using the optical disc device shown in FIG.
As a result of investigating the reproduction characteristic, the same result as in Example 5 was obtained.

Also, the rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the nickel substrate 2 of 5 kgf · mm or more, the Young's modulus of nickel E = 21900 kgf / m
m ² and nickel's Poisson's ratio v = 0.306 are given by the formula (1).
To the rigidity δ of the nickel substrate 2
The graph of FIG. 23 was obtained as a function of thickness. From the graph, it can be seen that the thickness of the nickel substrate 2 having a rigidity δ of 0.15 kgf · mm or more is 44 μm or more.

From the above, in the case of the optical disc 1 using the nickel substrate 2 as the metal substrate 2 constituting the disc substrate, stable focusing becomes possible by setting the thickness to 44 μm or more, and the ROM type optical disc 1 It can be said that the uneven pit information can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, when the nickel substrate 2 is used as the metal substrate 2, by setting the thickness to 44 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG.
When the nickel substrate 2 is used as the metal substrate 2, its thickness is more preferably set to 53 μm or more.

Example 9 Instead of the aluminum substrate 2 described in Example 5, a metal substrate 2 made of titanium is used.
Using (hereinafter, titanium substrate 2) and in the same procedure as in Example 5, an optical disk 1 made of the titanium substrate 2 was prepared, and was inserted into the cartridge case 37, and the optical disk device shown in FIG. As a result of investigating the reproduction characteristics in the same manner as in Example 1, the same results as in Example 5 were obtained.

Further, the rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the titanium substrate 2 of 5 kgf · mm or more, the Young's modulus of titanium E = 11600 kgf / m
Substituting m ² and the Poisson's ratio of titanium v = 0.321 into the equation (1), the rigidity δ of the titanium substrate 2 was obtained as a function of the thickness of the titanium substrate 2 to obtain the graph of FIG. From the graph, it is understood that the thickness of the titanium substrate 2 having a rigidity δ of 0.15 kgf · mm or more is 55 μm or more.

From the above, in the case of the optical disc 1 using the titanium substrate 2 as the metal substrate 2 constituting the disc substrate, stable focusing becomes possible by setting the thickness to 55 μm or more, and the ROM type optical disc 1 It can be said that the uneven pit information can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. However, when the titanium substrate 2 is used as the metal substrate 2, by setting the thickness to 55 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG. 24,
When the titanium substrate 2 is used as the metal substrate 2, the thickness is more preferably 66 μm or more.

Example 10 Instead of the aluminum substrate 2 described in Example 5, a metal substrate 2 made of a titanium alloy of Ti ₉₀ Al ₆ V ₄ (hereinafter, titanium alloy substrate 2).
Using the same procedure as in Example 5, an optical disc 1 made of a titanium alloy substrate 2 was prepared, and the optical disc 1 was inserted into a cartridge case 37. The optical disc device shown in FIG. As a result of investigating the reproduction characteristic, the same result as in Example 5 was obtained.

Also, the rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the titanium alloy substrate 2 of 5 kgf · mm or more, the Young's modulus of the titanium alloy E = 15000 kgf
/ Mm ² and the Poisson's ratio v = 0.33 of the titanium alloy were substituted into the equation (1), and the rigidity δ of the titanium alloy substrate 2 was obtained as a function of the thickness of the titanium alloy substrate 2 to obtain the graph of FIG.
From the graph, it can be seen that the titanium alloy substrate 2 having a rigidity δ of 0.15 kgf · mm or more has a thickness of 51 μm or more.

Therefore, the optical disc 1 using the titanium alloy substrate 2 as the metal substrate 2 constituting the disc substrate.
In this case, by setting the thickness to 51 μm or more, stable focusing becomes possible, and it can be said that the uneven pit information of the ROM type optical disc 1 can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. When the titanium alloy substrate 2 is used as the metal substrate 2,
By setting the thickness to 51 μm or more, stable focusing becomes possible and stable recording / reproduction can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG.
When the titanium alloy substrate 2 is used as the metal substrate 2, its thickness is more preferably 60 μm or more.

Example 11 As described in Example 5.
Instead of the aluminum substrate 2, Al_95.5Cu_FourMg _0.5
Made of duralumin, a type of aluminum alloy
Conducted using a metal substrate 2 (hereinafter, duralumin substrate 2)
In the same procedure as in Example 5, an optical device made of the duralumin substrate 2 was used.
Create the disk 1 and attach it to the cartridge case 37.
Example by inserting the optical disk device shown in FIG.
As a result of investigating the reproduction characteristics in the same manner as in Example 1,
The same result as in No. 5 was obtained.

The rigidity δ of the metal substrate 2 is 0.1.
In order to obtain the thickness of the duralumin substrate 2 of 5 kgf · mm or more, the duralumin Young's modulus E = 7150 kg
f / mm ² , Poisson's ratio of duralumin v = 0.335
Is substituted into the equation (1), and the rigidity δ of the duralumin substrate 2 is
The graph of FIG. 26 was obtained as a function of the thickness of the duralumin substrate 2. From the graph, the rigidity δ is 0.15 kgf · mm
It can be seen that the thickness of the duralumin substrate 2 described above is 65 μm or more.

From the above, in the case of the optical disc 1 using the duralumin substrate 2 as the metal substrate 2 constituting the disc substrate, by setting the thickness to 65 μm or more,
It can be said that stable focusing becomes possible and the concave and convex pit information of the ROM type optical disc 1 can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, when the duralumin substrate 2 is used as the metal substrate 2, by setting the thickness to 65 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG. 26,
When the duralumin substrate 2 is used as the metal substrate 2, the thickness thereof is more preferably 77 μm or more.

[0186] Example 12 instead of the aluminum substrate 2 as described in Example _{5, Cu 91.8 Sn 8 P 0.} 2 of the metal substrate 2 made of phosphor bronze consisting of a type of a copper alloy (hereinafter, phosphor bronze Using the substrate 2) and in the same procedure as in Example 5, an optical disc 1 made of the duralumin substrate 2 was prepared and was inserted into the cartridge case 37.
Using the optical disk device shown in FIG. 4, the reproduction characteristics were investigated in the same manner as in Example 1, and the same result as in Example 5 was obtained.

Also, the rigidity δ of the metal substrate 2 is 0.1.
Young's modulus of phosphor bronze E = 12000 kgf / m in order to obtain the thickness of phosphor bronze substrate 2 of 5 kgf · mm or more
Substituting m ² and Poisson's ratio v = 0.38 of phosphor bronze into the equation (1), the rigidity δ of the phosphor bronze substrate 2 was obtained as a function of the thickness of the phosphor bronze substrate 2 to obtain the graph of FIG. The graph shows that the thickness of the phosphor bronze substrate 2 having a rigidity δ of 0.15 kgf · mm or more is 55 μm or more.

From the above, in the case of the optical disc 1 using the phosphor bronze substrate 2 as the metal substrate 2 constituting the disc substrate, stable focusing becomes possible by setting the thickness to 55 μm or more, and the ROM type optical disc 1 It can be said that the uneven pit information of can be reproduced.

Although only the ROM type optical disc 1 is described here, the recordable and reproducible optical disc 1 shown in the second and third embodiments and the double-sided type optical disc 1'shown in the fourth embodiment. Also, when the phosphor bronze substrate 2 is used as the metal substrate 2, by setting the thickness to 55 μm or more, stable focusing becomes possible and stable recording / reproducing can be realized.

The focus error amount is ± 0.
In order to reduce the thickness to 1 μm or less, the rigidity of the metal substrate 2 is 0.24 k.
Since it is gf · mm or more, as seen from the graph of FIG.
When the phosphor bronze substrate 2 is used as the metal substrate 2, its thickness is more preferably 66 μm or more.

[Example 13] In Examples 1 to 12, a polycarbonate resin was used as the material of the cartridge case 37 (37 ') of the optical disk cartridge 50 (50'). In this embodiment, as shown in FIG. 17, a metal cartridge case 37 is used to further reduce the thickness of the cartridge.

When a polycarbonate resin was used as the material of the cartridge case 37, a wall thickness of at least 0.8 mm was required to maintain its rigidity, but when stainless steel was used, the wall thickness was 0 mm. .16 mm
As a result, it was possible to achieve the same rigidity.

As a result, when the optical discs 1 having the same thickness are used, the metal cartridge case 37 is used, so that the total thickness is 1 as compared with the case where the polycarbonate resin cartridge case 37 is used. .28 m
It was possible to realize a thin optical disk cartridge.

[0194]

As described above, the optical disk of the present invention has the following features.
At least a resin layer having a concavo-convex pit pattern and a metal reflective layer are sequentially formed on a metal substrate, and the total thickness of the optical disc is 0.3 mm or less.

As described above, the optical disc of the present invention has at least the resin layer having the concavo-convex pit pattern and / or the concavo-convex guide groove pattern and the optical recording layer formed at least sequentially on the metal substrate, and the total thickness of the optical disc. Is 0.3 mm or less.

As described above, the optical disc of the present invention has at least the resin layer having the concavo-convex pit pattern and the metal reflection layer formed on each of the front and back surfaces of the metal substrate at least in sequence, and the total thickness of the optical disc is 0.3 mm. It is characterized by the following.

Further, as described above, the optical disc of the present invention has at least the resin layer having the concave-convex pit pattern and / or the concave-convex guide groove pattern and the optical recording layer, which are sequentially formed on both the front and back surfaces of the metal substrate. The entire thickness is 0.3 mm or less.

As a result, even when the optical disc itself is thinned, it is possible to suppress the fluttering when the optical disc is rotated and to perform stable rotation, and not only the optical disc itself can be made thin, but also the optical disc device can be made thin. can do.

In particular, in each of the above-mentioned configurations, since the thickness of the entire optical disc is 0.3 mm,
As a result, even if the optical disk cartridge is housed in a resin-made optical disk cartridge case that has been often used conventionally, the thickness of the optical disk cartridge is 2.
When the thickness is 5 mm or less, it is possible to realize an optical disk device having a thickness of 5 mm.

When an optical disc having a thickness of 0.3 mm or less is formed by using a resin substrate such as polycarbonate which has been conventionally used, fluttering of the optical disc is generated when the optical disc is rotated at a high speed, and the optical disc becomes stable. However, by using a metal substrate as in the present invention, it is possible to perform stable high-speed rotation drive even for an optical disc having a thickness of 0.3 mm or less.

The present invention includes a structure in which each of the above-mentioned optical disks of the present invention is housed in an optical disk cartridge case to form an optical disk cartridge for the purpose of suppressing the adhesion of dust to the surface of the optical disk. By using an optical disk cartridge, it is possible to reduce the occurrence of errors.

As the optical disk cartridge,
Since the optical disc cartridge case is made of metal, the thickness of the cartridge case itself can be made thin, so that the optical disc cartridge can be made thinner and the optical disc device can be made thinner.

Further, the thickness of the entire optical disk cartridge is preferably 2.5 mm or less, which makes it possible to realize an optical disk device having a thickness of 5 mm.

In each of the optical disks of the present invention, the resin layer can be formed of an ultraviolet curable resin, and
A phase change recording medium or a magneto-optical recording medium can be used for the optical recording layer. Furthermore, it is desirable to provide a light-transmissive protective layer on the metal reflective layer or the optical recording layer from the viewpoint of protecting the metal reflective layer or the optical recording layer. As the light-transmissive protective layer, an ultraviolet curable resin is used. Layers formed from
It can be a layer made of a transparent resin sheet adhered with a transparent adhesive.

The optical disc of the present invention may be characterized in that the metal substrate has a rigidity of 0.150 kgf · mm or more. By making the rigidity of the metal substrate satisfy the above range, it is possible to easily realize the optical disk of the present invention having the above-described actions and effects.

As the metal substrate, one made of aluminum can be used. In this case, the thickness of the metal substrate is set to 66 μm or more, so that the optical disk of the present invention having the above-described actions and effects can be easily obtained. The effect that can be realized is achieved.

As the metal substrate, one made of iron may be used. In this case, the thickness of the metal substrate is set to 45 μm or more, whereby the optical disk of the present invention having the above-mentioned actions and effects can be easily obtained. The effect that can be realized is achieved.

Further, as the metal substrate, one made of copper can be used. In this case, the thickness of the metal substrate is set to 53 μm or more, whereby the optical disk of the present invention having the above-described action and effect can be easily obtained. The effect that can be realized is achieved.

Further, as the metal substrate, one made of nickel may be used, and in this case, the thickness of the metal substrate is set to 44 μm or more, whereby
It is possible to easily realize the optical disk of the present invention that has an effect.

As the metal substrate, one made of titanium may be used. In this case, the thickness of the metal substrate is 55 μm or more, so that the optical disk of the present invention having the above-described action and effect can be easily obtained. The effect that can be realized is achieved.

Further, as the metal substrate, a substrate made of an iron alloy containing iron as a main component can be used, and one example thereof is stainless steel made of Fe, Cr and Ni. The thickness of the substrate is 43
By setting the thickness to be equal to or more than μm, it is possible to easily realize the optical disk of the present invention having the above-described actions and effects.

Further, as the metal substrate, one made of a titanium alloy containing titanium as a main component can be used, and a titanium alloy made of Ti, Al, and V can be given as one example, and in that case. By setting the thickness of the metal substrate to be 51 μm or more, it is possible to easily realize the optical disk of the present invention having the above-described actions and effects.

Further, as the metal substrate, one made of an aluminum alloy containing aluminum as a main component can be used, and as a kind thereof, duralumin made of Al, Cu, and Mg can be used. By setting the thickness of the substrate to be 65 μm or more, it is possible to easily realize the optical disk of the present invention having the above-described actions and effects.

Further, as the metal substrate, a metal substrate made of a copper alloy containing copper as a main component can be used, and one example thereof is phosphor bronze made of Cu, Sn and P. If the thickness of the metal substrate in this case is 55 μm or more, the above-mentioned action and
It is possible to easily realize the optical disk of the present invention that has an effect.

The optical disk device of the present invention is an optical disk device for recording or reproducing data on or from the above-mentioned optical disk of the present invention or the optical disk cartridge of the present invention. It is characterized in that the metal reflection layer or the optical recording layer is irradiated with light.

With such a structure, the optical disc and the optical disc cartridge of the present invention described above are
It is possible to provide an apparatus capable of recording or reproducing information.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing a configuration of an optical disc according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the optical disc.

FIG. 3 is a drawing showing a state of a step in a method of manufacturing the optical disc.

FIG. 4 is a cross-sectional view of an optical disc in the process of manufacturing the optical disc.

FIG. 5 is a partial cross-sectional perspective view showing a surface state of a resin layer of the optical disc.

FIG. 6 is a partial cross-sectional perspective view showing another surface state of the resin layer of the optical disc.

FIG. 7 is a partial cross-sectional view showing in detail the structure of a recording medium layer of the optical disc.

FIG. 8 is a partial cross-sectional view showing another configuration of the recording medium layer of the optical disc in detail.

FIG. 9 is a partial cross-sectional view showing the configuration of the optical disc according to the embodiment of the present invention.

FIG. 10 is a drawing showing a state of one step in a method of manufacturing the optical disc of FIG.

FIG. 11 is a drawing schematically showing a configuration of an optical disc device according to an embodiment of the present invention.

12 is a drawing schematically showing a configuration of an optical pickup in the optical disc device of FIG.

FIG. 13 is a drawing schematically showing a configuration of an optical disc device according to an embodiment of the present invention.

FIG. 14 is a diagram schematically showing an optical disc cartridge according to an embodiment of the present invention and a configuration of an optical disc device including the optical disc cartridge.

FIG. 15 is a plan view of an optical disc cartridge.

FIG. 16 is a partial cross-sectional view of an optical disc cartridge.

FIG. 17 is a partial cross-sectional view of another optical disc cartridge.

FIG. 18 is a diagram schematically showing an optical disc cartridge according to an embodiment of the present invention and a configuration of an optical disc device including the optical disc cartridge.

FIG. 19 is a graph showing the relationship between the substrate thickness and the rigidity of a slenless substrate in an optical disc.

FIG. 20 is a graph showing the relationship between the substrate thickness and the rigidity of a substrate made of aluminum in an optical disc.

FIG. 21 is a graph showing the relationship between the substrate thickness and the rigidity of a substrate made of iron in an optical disc.

FIG. 22 is a graph showing the relationship between the substrate thickness and the rigidity of a substrate made of copper in an optical disc.

FIG. 23 is a graph showing the relationship between substrate thickness and rigidity of a substrate made of nickel in an optical disc.

FIG. 24 is a graph showing the relationship between the substrate thickness and the rigidity of a substrate made of titanium in an optical disc.

FIG. 25 is a graph showing the relationship between the substrate thickness and the rigidity of a substrate made of a titanium alloy in an optical disc.

FIG. 26 is a graph showing the relationship between substrate thickness and rigidity of a substrate made of duralumin in an optical disc.

FIG. 27 is a graph showing the relationship between substrate thickness and rigidity of a substrate made of phosphor bronze in an optical disc.

[Explanation of symbols]

1 optical disc 1'optical disc 2 metal substrate 3 resin layers 3'resin layer 4 Recording medium layer (optical recording layer) 4'metal reflective layer 5 Light-transmissive protective layer 6 Mirror plate 7 Transparent stamper 7'Transparent stamper 8 ultraviolet rays 9 Guide groove (concavo-convex guide groove pattern) 10 pits (uneven pit pattern) 23 Center Hub 24 spindles 25 optical pickup 26 Light receiving element for reproducing signal detection 27 Photodetector for control 28 Light emitting element 29 Light emitting and receiving element section 30 light beams 31 light collecting means 33 2-axis actuator 37 Optical disk cartridge case 37 'optical disk cartridge case 38 Inner wall surface on the upper side 39 Inner wall surface on the lower side 38 First opening 39 Second opening 40 slide shutter 41 suspension 42 magnetic head 43 Third opening 50 Optical disk cartridge 50 'optical disk cartridge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI theme code (reference) G11B 7/24 G11B 7/24 535L 571 571Y 7/004 7/004 Z 11/105 501 11/105 501A 521 521B 521C 521D 536 536C 541 541A 23/03 604 23/03 604P 604Z F term (reference) 5D029 JB18 JB32 KA22 KA23 KB14 KC09 LB13 LC08 MA34 PA09 5D075 FF20 FG04 FG14 CC14 DD0201090

Claims (37)

[Claims] 1. An optical disc, wherein a resin layer having a concave-convex pit pattern and a metal reflection layer are formed at least in sequence on a metal substrate, and the total thickness of the optical disc is 0.3 mm or less. 2. A concavo-convex pit pattern and // on a metal substrate.
Alternatively, at least a resin layer having an uneven guide groove pattern and an optical recording layer are sequentially formed, and the total thickness of the optical disk is 0.
An optical disc having a thickness of 3 mm or less. 3. An optical disc, wherein a resin layer having a concave-convex pit pattern and a metal reflective layer are formed at least sequentially on both front and back surfaces of a metal substrate, and the total thickness of the optical disc is 0.3 mm or less. 4. A resin layer having a concavo-convex pit pattern and / or a concavo-convex guide groove pattern and an optical recording layer are formed at least sequentially on each of the front and back surfaces of a metal substrate, and the total thickness of the optical disc is 0.3 mm or less. An optical disc characterized by. 5. The optical disc according to claim 1, wherein the resin layer is made of an ultraviolet curable resin. 6. The optical disc according to claim 2, wherein the optical recording layer is a recording layer using a phase change recording medium. 7. The optical disc according to claim 2 or 4, wherein the optical recording layer is a recording layer using a magneto-optical recording medium. 8. A light transmissive protective layer is provided on the metal reflective layer or the optical recording layer.
4. The optical disc according to any one of 4 to 4. 9. The optical disc according to claim 1, wherein the light-transmitting protective layer is made of an ultraviolet curable resin. 10. The optical disk according to claim 1, wherein the light-transmitting protective layer is made of a transparent resin sheet adhered with a transparent adhesive. 11. The rigidity of the metal substrate is 0.150 kg.
The optical disc according to any one of claims 1 to 10, wherein the optical disc has a length of f · mm or more. 12. The optical disk according to claim 1, wherein the metal substrate is made of aluminum. 13. The optical disk according to claim 12, wherein the metal substrate has a thickness of 66 μm or more. 14. The optical disk according to claim 1, wherein the metal substrate is made of iron. 15. The thickness of the metal substrate made of iron is 45 μm.
The optical disc according to claim 14, wherein the optical disc has a length of m or more. 16. The optical disc according to claim 1, wherein the metal substrate is made of copper. 17. The thickness of the metal substrate made of copper is 53 μm.
17. The optical disc according to claim 16, wherein the optical disc is m. 18. The optical disc according to claim 1, wherein the metal substrate is made of nickel. 19. The optical disk according to claim 18, wherein the metal substrate made of nickel has a thickness of 44 μm or more. 20. The optical disc according to claim 1, wherein the metal substrate is made of titanium. 21. The thickness of the metal substrate made of titanium is 5
The optical disc according to claim 20, which has a thickness of 5 μm or more. 22. The optical disc according to claim 1, wherein the metal substrate is made of an iron alloy containing iron as a main component. 23. The optical disk according to claim 22, wherein the iron alloy is stainless steel composed of Fe, Cr and Ni. 24. The optical disc according to claim 23, wherein the metal substrate made of stainless steel has a thickness of 43 μm or more. 25. The optical disc according to claim 1, wherein the metal substrate is made of a titanium alloy containing titanium as a main component. 26. The optical disc according to claim 25, wherein the titanium alloy is composed of Ti, Al and V. 27. The optical disc according to claim 26, wherein the metal substrate made of a titanium alloy of Ti, Al and V has a thickness of 51 μm or more. 28. The optical disc according to claim 1, wherein the metal substrate is made of an aluminum alloy containing aluminum as a main component. 29. The aluminum alloy comprises Al, Cu and M.
29. The optical disc according to claim 28, which is a duralumin composed of g. 30. The optical disk according to claim 29, wherein the metal substrate made of duralumin has a thickness of 65 μm or more. 31. The optical disk according to claim 1, wherein the metal substrate is made of a copper alloy containing copper as a main component. 32. The optical disk according to claim 31, wherein the copper alloy is phosphor bronze composed of Cu, Sn and P. 33. The optical disc according to claim 32, wherein the metal substrate made of phosphor bronze has a thickness of 55 μm or more. 34. An optical disk cartridge, wherein the optical disk according to any one of claims 1 to 33 is inserted in an optical disk cartridge case. 35. The optical disk cartridge case,
The optical disk cartridge according to claim 34, wherein the optical disk cartridge is made of metal. 36. The optical disk cartridge according to claim 34, wherein the thickness of the entire optical disk cartridge is 2.5 mm or less. 37. An optical disc device for recording or reproducing data on or from the optical disc according to any one of claims 1 to 33 or the optical disc cartridge according to any one of claims 34 to 36. An optical disk device characterized in that light is applied to a metal reflection layer or an optical recording layer from the side opposite to the substrate.