JPH09180248A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the track access time and to rapidly and stably recording/ reproduce massive information when a ROM layer is regenerated, and is written in a ROM layer in a process processing it by inter-layer movement processing and recording a focal point of a light beam. SOLUTION: The light beam 206 is focused on a track of the ROM layer 202, and an information signal is regenerated by the modulation data obtained from a pit. Further, the recording and erasing for the RAM layer is carried out by focusing the light beam 206 through ROM layer 202 and intermediate layer 204 on the track of the RAM layer 203. The reproduction is carried out by detecting the optical signal which is reflected and returns through the intermediate layer 204 and the ROM layer 202. When the light beam 206 is written in the RAM layer 203 in a process processing a regenerative signal on the track of the ROM layer 202, the focal point of the light beam 206 is subjected to inter-layer movement processing, and is recorded on the track of the RAM layer 203 existing in the same radius. Thus, the track access time is shortened, and a large volume of the information can be recorded/reproduced rapidly and stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc, and more particularly, to an optical disc having at least two or more layers capable of reading out a signal by irradiating a light beam in a direction perpendicular to a light beam incident surface. The present invention relates to a partial ROM disk in which a RAM section capable of recording / reproducing / erasing an information signal and a ROM section capable of only reproducing are provided on the optical disk.

[0002]

2. Description of the Related Art In recent years, RAM capable of recording / reproducing and erasing signals
A so-called partial ROM disc, which has a read-only portion, and a ROM portion in which a signal is recorded in advance and which can only read the signal, has been proposed and is generally used. According to Japanese Industrial Standard JIS X 6272 “90 mm rewritable and read-only optical disk cartridge”, the partially embossed disk corresponds to the partial ROM disk. (The international standard is ISO / IEC
Corresponding to 10090. In a conventional partial ROM disc, the information track of the RAM section is arranged on the inner peripheral side of the ROM as shown in FIG.
It is known that some information tracks have a structure in which they are located on the same layer on the outer peripheral side (for example, Japanese Patent Publication No.
(See Japanese Patent Publication No. 59494). In the figure, 901 is a partially embossed disk, 902 is a RAM section, that is, an area having an information track capable of recording / reproducing information signals, and 903 is R.
An OM portion, that is, an area having a track in which information is recorded and which can only be reproduced is shown. A partial radial cross-section of such a disc is shown in FIG. 1001 is a substrate made of transparent resin such as polycarbonate or PMMA, 1
Reference numeral 002 denotes a RAM section having an information track capable of recording / reproducing information signals, 1003 denotes a ROM section having a pre-recorded information-only track, and 1004 denotes a protective layer.

Further, as shown in FIG. 11, a RAM disk having a RAM section capable of recording a signal and a ROM disk having a ROM section to which a signal is previously fixed are fitted through a hollow portion, and 1 There is an optical disc having a structure of one disc (for example, Japanese Patent Publication No. 44106/1993). In FIG. 11, reference numeral 1101 denotes a substantially transparent ROM disk having concave and convex pits with a reflectance of 3 to 4%, 1102 a RAM disk having a recording film 1104 containing Te, for example, and 1103 a hollow portion. The surfaces of the ROM disk 1101 and the RAM disk 1102 on which the information signals are recorded are opposed to each other, and the ROM disk and the RAM disk are connected to each other at the outer periphery and the inner peripheral edge via a hollow portion 1103. The ROM disk and the RAM disk are detachably configured and can be combined with various disks according to the application.

Further, as a well-known example that has been conventionally known, there is a multi-layer optical disk as shown in FIG. 12, in which two or more recording layers whose optical constants change by irradiation of a light beam are laminated. This is intended to improve the recording density.

[0005]

In the first known example among those described in the prior art, firstly, since the RAM portion and the ROM portion are provided on the same layer, one surface of the disc Storage capacity is RAM area or RO
Secondly, when the information relating to the information in the ROM portion is to be recorded in the RAM portion without going over the disk having the M portion, the track to the RAM portion at a position distant from the ROM portion in the radial direction is formed. There is a problem in that access is required and it takes time until a recordable state occurs due to this physical distance. This problem can be solved by using a linear motor for high-speed access in the optical disk recording / reproducing apparatus, but in that case, there is a problem that the apparatus becomes complicated and the cost becomes high.

In the second known example of the prior art, since the ROM part and the RAM part are manufactured separately, the structure is different from that of the present invention in that the structure is not multi-layered and complicated. However, the ROM disk and the R disk have a high manufacturing cost, and the ROM disk and the RAM disk are detachable.
When replacing the AM disk, there is a problem that dust may be mixed into the hollow portion.

In the third known example of the prior art, a multi-layered structure is used only for the purpose of improving the recording density, and a partial ROM disk using a RAM part and a ROM part together is used. It is needless to say that no means for solving the above-mentioned problem that track access from the ROM section to the RAM section takes time is not provided.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is to reduce the storage capacity of the disk and to provide a RAM portion for recording signals. The present invention intends to provide an optical disc that shortens the time for which data can be recorded, eliminates the possibility of dust and the like entering between layers of each RAM and ROM, and enables large-capacity high-speed stable recording / reproducing / erasing of signals. It is a thing.

[0009]

In order to achieve the above object, an optical disk according to the present invention has a plurality of layers (ROM layer or RAM layer) from which a signal can be read by irradiating a light beam, At least one of the layers is a layer capable of recording / reproducing and erasing (RAM layer), and the other layer is a layer capable of only reproducing (ROM layer), and has a multilayer structure.

Then, a layer (R
As for the AM layer), since the energy of the light beam must be strong when recording and erasing the signal, the layer capable of recording / reproducing / erasing is a layer in which at least two or more layers are arranged in the direction perpendicular to the light beam incident surface. Of these, it is preferable to be provided at a position closest to the surface on which the light beam is incident.

The recording / reproducing erasable layer has a phase in which a crystalline state and an amorphous state undergo a reversible phase change due to heating or cooling, thereby changing an optical constant and recording or erasing information. A changing film can also be used.

When the phase change film as described above is used for the recording / reproducing / erasable layer, the recording / reproducing / erasable layer is previously formed on the entire surface of the layer for the reason described later.
It is desirable to record the signal. The information content of the signal may or may not have meaning.

Further, the layer capable of recording / reproducing / erasing a signal is
The magneto-optical film may be configured to change the optical characteristics by setting the direction of the magnetic poles upward or downward to enable recording / reproducing / erasing of signals.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial radial cross-sectional view of an optical disk according to an embodiment of the present invention, which particularly corresponds to claim 1 and other claims 8, 9, and 13. In the figure, 101 is a substrate made of transparent resin such as polycarbonate or PMMA, and its thickness is about 0.58 mm. The substrate 10
On the surface of the No. 1 102 side, by molding beforehand,
Fine information pits are formed. 102 is formed on the information pit. Reference numeral 102 denotes a ROM layer made of a thin film such as aluminum or gold that can only reproduce a signal, and is formed by sputtering or vapor deposition. Reference numeral 105 denotes a protective layer, which is made of a transparent resin such as polycarbonate or PMMA similar to that of the substrate 101, and has a thickness of about 0.58 mm. When forming a guide groove (groove) for guiding the light beam to a predetermined position at the time of recording / reproducing / erasing an information signal, the surface of the protective layer 105 is formed on the surface of the protective layer 105 on the 103 side by molding. The groove is formed in advance. Such a protective layer 105
Form 103 on top. Reference numeral 103 is a RAM layer composed of a recording film capable of recording / reproducing / erasing a signal. That ram
Each of the layer 103 and each of the ROM layers 102 has a very small thickness, which is on the order of nm. A transparent substrate 101 on which the ROM layer 102 is formed,
The protection layer 105 on which the RAM layer 103 is formed is
104 so that the layer 102 and the RAM layer 103 face each other.
And bonded to form one optical disk. 104
Is an intermediate layer that separates and adheres the ROM layer 102 and the RAM layer 103, is formed of a transparent member having a high light beam transmittance, and has a thickness of about 40 μm. An example of the transparent member is an ultraviolet curable resin. For example, an ultraviolet curable adhesive model number KZ86 made by Japan Synthetic Rubber is used.
11 J (in the case of a light beam having a wavelength of 650 nm, its transmittance is 99% or more) is used. As described above, the respective layers are laminated to form a layered structure, and the total disc thickness is designed to be 1.2 mm. The ROM layer 102, RA
The M layer 103 and the intermediate layer 104 are formed over the entire effective surface of the optical disc. Alternatively, the RAM layer 10
A ROM portion in which ROM data is previously recorded by information pits may be provided in part of 3 to form a partial RAM layer.

A light beam 106 is emitted from the substrate 101 side. When the signal is reproduced by the ROM layer 102, the light beam 106 is controlled so as to focus on the ROM layer 102. Further, when recording, reproducing, or erasing a signal in the RAM layer 103, the light beam 106 is controlled so as to focus on the RAM layer 103.

FIG. 2 shows the RA of the optical disc of FIG.
When recording, reproducing, or erasing a signal in the M layer,
It is a figure which shows the state of irradiation of a light beam at the time of reproducing a signal by an OM layer. The state of FIG. 2 (a) is RO
The case of reproducing the M layer is shown, and the state of FIG.
The case of recording, reproducing, or erasing on a layer is shown. 2 in the figure
01 is a substrate, 202 is a ROM layer, 203 is a RAM layer, 2
Reference numeral 04 is an intermediate layer, 205 is a protective layer, and 206 is a light beam, and the characteristics of the respective constituent elements are the same as in the case of FIG.

The reproduction of the signal by the ROM layer is shown in FIG.
As shown in FIG. 3, by focusing the light beam 206 on the information track of the ROM layer 202 and reproducing the modulated data obtained from the information pits formed on the information track of the ROM layer 202, Reproduce the information signal. In addition, recording / erasing or reproducing to / from the RAM layer is performed as shown in FIG.
As shown in (b), the light beam 206 is focused on the information track of the RAM layer 203 via the ROM layer 202 and the intermediate layer 204. When reproducing from the RAM layer 203, the light beam focused on the RAM layer is reflected,
This is performed by detecting an optical signal returning via the intermediate layer 204 and the ROM layer 202.

The light beam 206 is emitted from the ROM layer 2 of FIG.
In the process of reproducing the information track No. 02 and processing the data of the reproduced signal, when the related data is recorded in the RAM layer 203, the focus of the light beam 206 is moved between layers, and In this state, the information is recorded on the information track on the RAM layer 203 located at the substantially same radius of the ROM layer 202. By performing such processing, the moving distance of the light beam can be set to several tens of μm at most, and the track access between the information track of the ROM layer and the information track of the related RAM layer can be performed in a short time. . And
In this case, it is not necessary to use a linear motor for high speed access as in a conventional partial ROM disc having a ROM section and a RAM section in the same plane.

As a method of using the RAM layer, the data relating to the data of the reproduction signal from the information track of the ROM layer as described above is located at substantially the same radius of the ROM layer.
In addition to recording in the information track of the AM layer, the versioned data can be stored in the RAM layer when the computer software is upgraded.

FIG. 3 illustrates the invention, in particular claim 11 and claim 12, as well as claim 1, claim 2 and claim 13.
FIG. 6 is a partial cross-sectional view in the radial direction of the optical disc according to the embodiment corresponding to FIG. In the figure, 301 is a transparent substrate made of a transparent resin capable of transmitting a light beam, 302 is a RAM layer composed of a recording film capable of recording / reproducing signals, and 303 is a first ROM layer capable of only reproducing signals, 304 Is the RAM layer 30
2 is a first intermediate layer separating the first ROM layer 303 from the second ROM layer, and 305 is a second ROM layer capable of reproducing only a signal, 3
Reference numeral 06 is a second intermediate layer that separates the first ROM layer 303 from the second ROM layer 305, 307 is a third ROM layer that can only reproduce signals, and 308 is a second ROM layer 305.
Is a third intermediate layer for isolating the third ROM layer 307 and 309 is a protective layer. 310 is a light beam,
Irradiation is performed from the substrate 301 side.

An example of a method of manufacturing the optical disc shown in FIG. 3 will be described below. First, the substrate 301 is made of transparent resin such as polycarbonate or PMMA to a thickness of about 0.54 mm. R of the substrate 301
When the above-mentioned guide groove (groove) is provided on the surface of the AM layer 302 side, the groove is previously formed on the surface by molding. On such a transparent substrate 301, RA
The M layer 302 is formed. Subsequently, an intermediate layer 304 made of photopolymer having fine information pits formed on the ROM layer 303 side is formed on the RAM layer 302 by the 2P (photopolymer) method. Then, the intermediate layer 304
The ROM layer 303 is formed thereon. A member of the optical disc manufactured in this manner is referred to as a member A. on the other hand,
The protective layer 309 is made of the same transparent resin as the substrate 301 and has a thickness of about 0.54 mm. Its protective layer 3
On the surface of the 09 of the ROM layer 307 side, fine information pits are formed in advance by embossing by molding. Then, the ROM layer 307 is formed on the information pit. Then, an intermediate layer 308 having fine information pits formed on the ROM layer 305 side is formed on the ROM layer 307 by the same 2P method as described above. And the intermediate layer 30
The ROM layer 305 is formed on the upper surface 8. The member of the optical disc manufactured in this manner is referred to as member B. The member A and the member B are adhered to each other by the intermediate layer 306 made of the ultraviolet curable resin to manufacture one optical disk. The intermediate layers 304, 306, and 3 described above are used.
08 is made to have a thickness of about 40 μm. Also, R
The OM layers 303, 305, and 307 are made of a thin film of aluminum or gold and are produced by sputtering or vapor deposition. RAM layer 302 and 303, 305, 30
The thickness of each ROM layer of No. 7 is very small and is on the order of nm. Each of these layers described above is laminated to form a layered structure and is designed so that the total disc thickness is 1.2 mm. In the optical disc configured as described above, it is possible to record the information related to the data reproduced from the information tracks on the first, second and third ROM layers on the RAM layer 302 at substantially the same radius. Become.

FIG. 4 is a partial radial cross-sectional view of an optical disk according to an embodiment of the present invention, particularly claim 2 and others corresponding to claim 1, claim 8, claim 10 and claim 13. Is. In the figure, 401 is polycarbonate or PMM.
The substrate is made of a transparent resin such as A, and the thickness of the layer is about 0.58 mm. When forming the above-mentioned guide groove (groove) on the surface of the transparent substrate 401 on the 402 side,
The groove is formed in advance by molding. On the substrate 401, a RAM layer 402 composed of a recording film capable of recording / reproducing / erasing signals is formed. 405
Is a protective layer having a thickness of about 0.58 mm, and is made of the same material as the substrate 401. In addition,
Fine information pits are formed in advance on the surface of the protective layer 405 on the 403 side by molding. On the information pit, a ROM layer 403 capable of only reproducing a signal
Is formed. The ROM layer 403 and the above RA
Each of the M layers 402 has a very small thickness on the order of nm. The transparent substrate 401 on which the RAM layer 402 is formed and the protective layer 40 on which the ROM layer 403 is formed
5 are bonded by 404 so that the RAM layer 402 and the ROM layer 403 face each other. Reference numeral 404 denotes an intermediate layer that adheres the RAM layer 402 and the ROM layer 403 to each other and separates them from each other. The intermediate layer 404 is formed of a transparent member such as an ultraviolet curing resin and has a thickness of about 40 μm. Of the layers arranged in the direction perpendicular to the light beam incident surface as shown in FIG. 4, by setting the position of the RAM layer at a position close to the light beam incident surface, the energy of the strong light beam is generally increased. It is possible to efficiently record information on the required information track of the RAM layer. The RAM layer 4
02, the ROM layer 403, and the intermediate layer 404 are formed over the entire effective surface of the optical disc. Or R
A ROM portion in which ROM data by information pits is recorded in advance may be provided in a part of the AM layer 402 to form a partial RAM layer. A light beam 406 is emitted from the substrate 401 side. When recording, reproducing, or erasing a signal in the RAM layer 402, the light beam 406 is applied to the RAM layer 402.
Controlled to focus on. In addition, the ROM layer 40
In the case of regenerating a signal by means of 3, the light beam 40
6 is controlled to focus on the ROM layer 403.

FIG. 5 shows the RA of the optical disk of FIG.
When recording, reproducing, or erasing a signal in the M layer,
It is a figure which shows the irradiation state of a light beam at the time of reproducing a signal by an OM layer. The state of FIG. 5A shows the case where the signal is reproduced by the ROM layer, and the state of FIG. 5B shows the case where the signal is recorded, reproduced, or erased in the RAM layer. In the figure, 501 is a substrate, 502 is a RAM layer, 503.
Is a ROM layer, 504 is an intermediate layer, 505 is a protective layer, 506
Is a light beam, and the characteristics of each component are the same as in the case of FIG.

The reproduction of the signal by the ROM layer is shown in FIG.
As shown in FIG. 7, the light beam 506 is focused on the information track of the ROM layer 503 through the RAM layer 502 and the intermediate layer 504, and reflected from the information pit formed on the information track of the ROM layer 503. The detected optical signal is detected via the intermediate layer 504 and the RAM layer 502, and the modulated data is reproduced to reproduce the information signal from the ROM layer 503. Further, recording / erasing or reproduction of a signal to / from the RAM layer is performed by focusing the light beam 506 on the information track of the RAM layer 502, as shown in FIG. 5B. RA
The reproduction of the signal from the M layer 502 is performed by detecting the optical signal that returns when the light beam focused on the RAM layer is reflected.

Of the layers arranged at least two or more in the direction perpendicular to the light beam incident surface, the recording / reproducing / erasable layer is
By providing the position closest to the light beam incident surface,
It is possible to accurately record a signal in a layer capable of recording / reproducing and erasing.

The light beam 506 is emitted from the ROM layer 5 of FIG.
In the process of reproducing the signal of the information track No. 03 and processing the data of this reproduced signal, the related data is recorded in the RAM layer 50.
In the case of recording to No. 2, the focal point of the light beam 506 is subjected to interlayer movement processing so as to be in the state of FIG. 5B, and recording is performed to the information track on the RAM layer 502 located at substantially the same radius of the ROM layer 503. By performing such processing, the moving distance of the light beam can be set to several tens of μm at most, and the track access between the information track of the ROM layer and the information track of the related RAM layer can be performed in a short time. .

As described above, among the layers arranged at least two or more in the direction perpendicular to the light beam incident surface, the recording / reproducing erasable layer is provided at the position closest to the light beam incident surface, thereby recording / reproducing / erasing. It is possible to efficiently record a signal on a possible layer.

FIG. 6 shows a radial direction of an optical disk according to an embodiment of the present invention, particularly claim 4 and others corresponding to claim 1, claim 2, claim 8, claim 10 and claim 13. FIG. In FIG. 6A, 601
Is a substrate made of transparent resin such as polycarbonate or PMMA, 602 is a RAM layer capable of recording / reproducing / erasing signals,
Reference numeral 603 is a ROM layer capable of only reproducing signals, and 604 is RA.
An intermediate layer that separates the M layer 602 and the ROM layer 603,
Reference numeral 605 is a protective layer. The characteristic of this figure is that RA
That is, the M layer 602 is formed of a phase change film. This phase change film causes a reversible phase change between, for example, a crystalline state and an amorphous state by heating and cooling by irradiation of a light beam with output control, and changes optical constants such as reflectance. As a result, signals can be recorded and erased. When reading a signal, the output of the light beam is reduced to about 1/10 of that at the time of recording. When this phase change film is used as a RAM layer, the phase change film has a high CN ratio even when a light beam of a short wavelength is used, and a magnetic field required when a magneto-optical film or the like is used as a RAM layer. Since the generation device is not required, the structure of the optical disk recording / reproducing device can be simplified, and the operation of recording another signal in the RAM layer in which the signal is recorded is performed only by controlling the output of the light beam. It becomes possible to make it easy. The features of the other components are the same as those in the case of FIG. A light beam 606 is emitted from the substrate 601 side. When recording, reproducing, or erasing a signal in the RAM layer 602, the light beam 606 is used.
Are controlled to focus on the RAM layer 602. Further, when a signal is reproduced by the ROM layer 603,
The light beam 606 is controlled to focus on the ROM layer 603.

FIG. 6B shows an embodiment in which FIG. 6A is put to practical use. In FIG. 6B, R
The AM layer 602 is accompanied by a protective layer 607 and a reflective layer 608 formed by sputtering or vapor deposition to form a RAM layer having a multilayer structure. ZnS is used as the protective layer 607.
-SiO2 or the like, the reflective layer 608 is an aluminum alloy or the like, and the phase change film 602 is Ge2Sb2Te5 or the like.
For example, use.

As described above, by using the phase change film as the recordable / erasable layer, the CN ratio is high even when a light beam of a short wavelength is used, and a magneto-optical film or the like is used as the RAM layer. When used, a necessary magnetic field generator is not required, so that the structure of the optical disk recording / reproducing apparatus can be simplified and the RA in which a signal is recorded is used.
The operation of further recording a signal in the M layer can be easily performed only by controlling the output of the light beam.

Next, the description of FIG. 7 relating to claim 3 and claim 5 will be made in the case of the embodiment shown in FIG.
The reproduction signal level from the layer is performed. The vertical axis of FIG. 7 is R
The horizontal axis represents the HF reproduction signal level reproduced from the ROM layer via the AM layer, and the horizontal axis represents time. FIG. 7A shows an example of the ROM layer reproduction signal level when the information signal is recorded only on a part of the RAM layer. Further, FIG. 7B shows an example of the ROM layer reproduction signal level when a random information signal is recorded in advance on the entire surface of the RAM layer. FIG. 7 (a)
As shown in, when the information signal is recorded only in a part of the RAM layer, the transmittance changes when passing through the RAM layer in which the information signal is recorded, and the ROM layer reproduction signal level changes. However, stable signal reproduction becomes difficult. On the other hand, when the information signal is recorded on the entire surface of the RAM layer, as shown in FIG. 7B, the transmittance does not change, and the ROM layer reproduction signal level does not change.
Stable signal reproduction is possible. Therefore, as described in claim 5, it is meaningless to the optical disk shown in FIG. 6 over the entire surface of the recordable / rewritable erasable layer when the optical disk is first used by a person who first uses the optical disk. Signal has already been recorded, in other words, before reproducing or recording / erasing the information signal from the optical disc,
Insignificant meaningless data in the RAM layer, for example, a signal that becomes a pattern that repeats the minimum mark or an irregular random signal that does not have meaning is recorded on the entire surface of the RAM layer, and information to the RAM layer is recorded. Only when recording becomes necessary, the data recorded in advance is overwritten. Note that the meaningless data signal described above is, for example, a RAM
When substituting a layer as a temporary ROM layer,
Of course, it may be a signal of data having meaningful information property.

As described above, when the recording / reproducing / erasable layer is composed of the phase change film, the signal from the layer only capable of reproducing the signal by previously recording the signal on the entire surface of the layer. Can be detected stably and accurately.

FIG. 8 is a radial direction of an optical disk according to an embodiment of the present invention, particularly claim 7, and other embodiments corresponding to claim 1, claim 2, claim 8, claim 10, and claim 13. FIG. In the figure, 801 is a substrate made of transparent resin such as polycarbonate or PMMA, 802
Is a RAM layer capable of recording / reproducing signals and erasing, 803 is a ROM layer capable of only reproducing signals, and 804 is a RAM layer 802 and RO.
An intermediate layer that adheres and separates the M layer 803, and 805 is a protective layer. A feature of FIG. 8 is that a RAM
That is, the layer 802 is composed of a magneto-optical film. The magneto-optical film can reproduce or record / erase information by setting the direction of its magnetic pole upward or downward. The features of the other constituent elements are the same as those in FIG.

A light beam 806 is emitted from the substrate 801 side. When recording, reproducing, or erasing a signal in the RAM layer 802, the light beam 806 emits light to the RAM layer 8.
Controlled to focus on 02. Further, when the signal is reproduced by the ROM layer 803, the light beam 806 is controlled so as to focus on the ROM layer 803. When the RAM layer 802 formed of a magneto-optical film is used, the transmittance and the reflectance of the RAM layer 802 hardly change between the case where information is recorded and the case where information is not recorded, and the ROM The information reproduction signal of the layer 803 is hardly affected.

By thus forming the recording / reproducing / erasable layer with the magneto-optical film, it is possible to record a signal in the recording / reproducing / erasable layer in advance, which is required in the case of the phase change film. It is possible to stably read a signal from a layer that can only reproduce the signal.

[0036]

Since the present invention is configured as described above, it has the following effects. In a multilayer optical disc in which at least two layers (RAM layer or ROM layer) capable of reading a signal by irradiating a light beam are arranged in a direction perpendicular to the light beam incident surface, the above signal can be read. At least one recording / reproducing / erasable layer (RAM layer) capable of recording and erasing a signal in addition to reading a signal from a possible layer (RAM layer or ROM layer), and reading a signal. By configuring with a layer that can only be read (ROM layer), the recording capacity from the ROM layer to the RAM layer for recording signals can be shortened without reducing the storage capacity of the disk, and further, each RAM Layer and R
It is possible to eliminate the risk of dust and the like being mixed between the OM layers, and to perform high-speed and stable recording / reproduction / erasure of a signal with a large capacity.

[Brief description of the drawings]

1 is a sectional view showing an embodiment of the present invention, particularly according to claim 1;

FIG. 2 is a diagram for explaining reproduction of an optical disc according to an embodiment of the present invention, particularly claim 1;

FIG. 3 is a sectional view showing an embodiment of the present invention, particularly according to claims 11 and 12;

FIG. 4 is a sectional view showing an embodiment according to claim 2 of the present invention.

FIG. 5 is a diagram for explaining reproduction of an optical disc according to an embodiment of the present invention, particularly claim 2;

FIG. 6 is a sectional view showing an embodiment according to claim 4 of the present invention.

FIG. 7 is a diagram for explaining signal reproduction in an embodiment according to claim 5 of the present invention;

FIG. 8 is a sectional view showing an embodiment according to claim 7 of the present invention.

FIG. 9 is a schematic diagram showing a first conventional example.

FIG. 10 is a partial sectional view showing a first conventional example.

FIG. 11 is a partial sectional view showing a second conventional example.

FIG. 12 is a partial sectional view showing a third conventional example.

[Explanation of symbols]

101, 401, 1001, 1203 Substrate 102, 303, 403 RO
M layer 103, 302, 402 RA
M layer 104, 304, 404, 1202 Intermediate layer 105, 405, 607, 1004, 1204 Protective layer 608 Reflective layer 106, 310, 406 Light beam 901 Partial ROM disk 902, 1002 RA
M part 903, 1003 RO
M part 1101 RO
M disk 1102 RA
M disk 1103 Hollow part 1104, 1201 Recording film

Claims (13)

[Claims] 1. A multilayer optical disc in which at least two layers capable of reading a signal by irradiating a light beam are arranged in a direction perpendicular to a light beam incident surface, and the signal can be read. An optical disc, wherein the layer is composed of at least one recording / reproducing / erasable layer capable of recording / erasing a signal in addition to reading a signal, and a layer only capable of reading a signal. . 2. The recording / reproducing / erasable layer is provided at a position closest to the light beam incident surface among at least two layers arranged in a direction perpendicular to the light beam incident surface. The optical disc according to claim 1. 3. A recording / reproducing / erasable layer capable of recording / erasing a signal in addition to reading a signal by irradiating a light beam, and a recording / reproducing / erasable layer. In a multi-layer optical disc comprising a layer capable of only reading out a signal by irradiating a light beam, a layer capable of recording / reproducing and erasing is a layer of the multi-layered optical disc. An optical disc in which a meaningless signal is already recorded over the entire surface of the recordable / reproducible erasable layer when first used by a person who first uses. 4. The optical disc according to claim 2, wherein the recordable / reproducible layer is a phase change film. 5. The signal can be read in a multi-layered optical disc in which at least two layers capable of reading the signal by irradiating the light beam are arranged in a direction perpendicular to the light beam incident surface. The layer is composed of at least one recording / reproducing / erasable layer capable of recording / erasing a signal in addition to reading a signal, and a layer only capable of reading a signal. The layer is a layer formed of a phase change film, which is provided at a position closest to the light beam incident surface among at least two layers arranged in a direction perpendicular to the light beam incident surface, and the multilayer optical disc is A structure in which a meaningless signal is already recorded over the entire surface of the recordable / erasable layer when first used by a person who uses the multilayer optical disk for the first time. An optical disc comprising: 6. The method according to claim 3, wherein instead of the meaningless signal, a signal having meaningful information property is recorded over the entire surface of the recording / reproducing / erasable layer. Item 5. The optical disk according to item 5. 7. The optical disc according to claim 2, wherein the recording / reproducing / erasable layer is composed of a magneto-optical film. 8. A transparent substrate capable of transmitting light, a first layer formed on one surface of the transparent substrate and capable of reading a signal, and a first layer capable of reading the signal. An intermediate layer made of an ultraviolet curable resin which is formed on one surface and is opposite to the surface on which the transparent substrate is formed, can transmit light, and is cured by irradiation of ultraviolet rays, and the intermediate layer. A second layer capable of reading a signal formed on one surface of the first layer capable of reading the signal and a surface opposite to the surface having the first layer capable of reading the signal; and reading the signal. 2. The optical disc according to claim 1, further comprising a protective layer formed on one surface of the second layer that is capable of being formed and on a surface opposite to the surface on which the intermediate layer is formed. 9. The information signal is expressed on the one surface of the transparent substrate where the first layer from which the signal can be read is formed and the surface on which the first layer from which the signal can be read is formed. Second layer which is formed of a metal reflective layer capable of reflecting the light formed on the information pit with the information pit formed by molding in advance as a shape to be read, and capable of reading the signal Is constituted by the layer capable of recording / reproducing and erasing.
The described optical disc. 10. The first layer from which the signal can be read is constituted by the recording / reproducing / erasable layer,
In addition, the second layer from which the signal can be read has a shape for expressing an information signal on one surface of the protective layer on which the second layer from which the signal can be read is formed. 9. A metal reflective layer capable of reflecting the light formed on the information pit together with the information pit formed by molding in advance.
The described optical disc. 11. A multilayer optical disc in which at least three layers from which a signal can be read by irradiating a light beam are arranged in a direction perpendicular to a light beam incident surface are arranged as one outermost layer. It is possible to read out the signal, which is disposed between the transparent substrate capable of transmitting the generated light, the protective layer disposed as the other outermost layer, and at least three or more disposed between the transparent substrate and the protective layer. And a plurality of intermediate layers made of a material capable of transmitting light while isolating each of the layers capable of reading the signal, and a layer capable of reading the signal. A read / write erasable layer of at least one layer capable of recording and erasing the signal in addition to reading the signal, and a layer only capable of reading the signal. Optical disc. 12. The optical disk according to claim 11, wherein the intermediate layer includes one intermediate layer made of an ultraviolet curable resin and at least one intermediate layer made of a photopolymer. . 13. The intermediate layer has a thickness of about 40 μm, and the optical disc has a total thickness of about 1.2 mm.
The optical disc according to claim 8 or 11, wherein the optical disc is configured to: