WO2003034411A1

WO2003034411A1 - Method and apparatus for initializing multi-layered recording layer type optical recording medium

Info

Publication number: WO2003034411A1
Application number: PCT/JP2002/010497
Authority: WO
Inventors: Tsuyoshi Komaki; Tetsuro Mizushima; Jiro Yoshinari
Original assignee: Tdk Corporation
Priority date: 2001-10-15
Filing date: 2002-10-09
Publication date: 2003-04-24
Also published as: JP2005092902A; TWI220986B

Abstract

A method for initializing a multi-layered recording layer type optical recording medium including a plurality of layers (L1, L0) each containing a recording layer to be initialized by irradiation of light, which layers are stacked in this order on one side of a substrate via a spacer layer (12) formed between the layers (L1, L0). Initialization of one layer (L0) among the plurality of layers (L0, L1) is performed by applying light from the layer (L0) side by using an object lens (31) having numerical aperture NA which satisfies an equation [TH x NA ≥ 9] wherein TH (µm) is thickness of a spacer layer (12) adjacent to the surface of the substrate (2) side in the layer (L0). Thus, it is possible to uniformly initialize the layers (L1, L0) containing the recording layers.

Description

Itoda »

Initialization method of multilayer recording layer type optical recording medium

Device for initializing multi-layer recording optical media

The present invention relates to a multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation are laminated on one surface side of a substrate and a spacer layer is formed between each layer. The present invention relates to an initialization method and an initialization device. Background art

Optical recording media are noted for their high density and large capacity, and are used for various purposes. In particular, rewritable optical recording media that allow erasing and re-recording of recorded information can be used to restore and update data, and can be repeatedly rewritten and used, contributing to expanding the use of optical recording media. It is expected to do. As this type of optical recording medium, a magneto-optical recording medium (MO) and a phase change optical recording medium have been developed and commercialized.

Among them, the inventors have already developed an optical recording medium 1 having a layer structure shown in FIG. 5 as a rewritable phase-change optical recording medium utilizing a phase change (hereinafter, also simply referred to as an optical recording medium). ing. The optical recording medium 1 is configured such that a reflective layer 3, a recording layer 4, and a cover layer 5 as a light transmitting layer are sequentially laminated on one surface (upper surface in FIG. 1) of a substrate 2. In this case, the base material 2 is formed into a flat plate shape (for example, a disk (disc) shape) having a predetermined thickness by injection molding using a resin material such as polycarbonate. On the surface of the substrate 2 (the upper surface in the figure), fine irregularities (not shown) such as groups for tracking servo are formed at the time of molding. The reflective layer 3 is formed on the surface of the base material 2 on which fine irregularities are formed using a metal such as A1, Ag, or Ni. The recording layer 4 has a first protective layer 4a, a phase change material layer 4b, and a second protective layer 4c, and these layers 4c, 4b, and 4a are laminated on the reflective layer 3 in this order. Sa It is composed. The first protective layer 4 a and the second protective layer 4 c of this, For example, formed by using a dielectric material such as aluminum oxide or Z n S- S i O _2, the phase change material layer 4 b is For example, it is formed using GeTeSb, InSbTe, or AgGeInSbTe. The cover layer 7 is formed on the first protective layer 4a using a light-transmitting resin material.

In this optical recording medium 1, the recording layer 4 is irradiated with a laser beam set on the recording layer from the force bar layer 5 side, and the recording layer 4 including the phase change material layer 4b is formed into an amorphous state. The recording mark is formed and erased by reversibly changing the phase with the crystalline state. In other words, when the recording layer 4 (particularly the phase change material layer 4b) is irradiated with a laser beam of recording power, the irradiated part is rapidly cooled (rapidly cooled) after being heated to a temperature higher than its melting point. As a result, the recording mark becomes amorphous according to the recording signal. In addition, when the recording layer 4 is irradiated with a laser beam having a recording power, the irradiated portion is heated to a temperature higher than a crystallization temperature and then gradually cooled (gradually cooled) to be crystallized, thereby forming a recording mark. Will be erased. On the other hand, at the time of reproduction, the light reflectance that changes with the change in the optical constant between the amorphous state and the crystalline state when a laser beam of reproduction power (a laser beam of lower power than during recording) is irradiated. The data is reproduced by determining the presence or absence of a recording mark using the difference between the data.

When manufacturing the optical recording medium 1, first, the base material 2 is formed into a disk shape having fine irregularities such as a groove formed on the surface thereof by injection molding. Next, after forming the reflective layer 3 on one surface side of the substrate 2, the recording layer 4 is formed on the reflective layer 3. At this time, the phase change material layer 4b and the first and second protective layers 4a and 4c are generally formed by a sputtering method. Next, the cover layer 5 is formed on the recording layer 4 by, for example, spin coating. In this case, the phase change material layer 4b in the recording layer 4 is in an amorphous state immediately after its formation, and cannot be recorded by the user as it is. Therefore, the user can immediately start using the optical recording medium 1. In order to ship the optical recording medium 1 in the initialized state, it is necessary to initialize the recording layer 4 (particularly, the phase change material layer 4 b) in the manufacturing process of the optical recording medium 1. For this reason, after forming the force bar layer 5, the recording layer 4 is initialized. In this case, a laser beam set to a high power (initialization power) from the same direction (the direction from the cover layer 5 side) as the irradiation direction of the laser beam irradiated at the time of reproduction or recording (hereinafter, “initialization power”) Of the recording layer 4). At this time, the optical recording medium 1 is normally irradiated with an initialization laser beam through an objective lens having a numerical aperture NA of about 0.4 (for example, a value of 0.34). Thus, the manufacture of the optical recording medium 1 in which the recording layer 4 has been initialized is completed.

However, it is desired to develop and commercialize an optical recording medium having a larger capacity, and the inventor has developed an optical recording medium 11 having a larger capacity based on the optical recording medium 1. The optical recording medium 11 will be described with reference to FIG. Note that the same components as those of the optical recording medium 1 are denoted by the same reference numerals, and redundant description will be omitted.

This optical recording medium 11 is a so-called single-sided multilayer (for example, two layers) recording layer type optical recording medium (hereinafter, also referred to as “multilayer recording layer type optical recording medium”), as shown in FIG. On one side of the material 2 (the upper surface in the figure), an L1 layer including a reflective layer 3 and a recording layer 4, a spacer layer 12 as a light transmitting layer, and a recording layer 14 (hereinafter, referred to as "L 0 layer J") and a cover layer 5 as a light transmitting layer are sequentially laminated. In this case, the spacer layer 12 has a thickness TH of usually 20 μηι. The surface of the L0 layer side has fine irregularities such as groups, etc. The recording layer 14 has a first protective layer 14a, a phase change material layer 14b, and a second protective layer. It has a layer 14c, and these layers 14c, 14b, 14a are laminated on the fine uneven surface of the spacer layer 12 in this order. In this case, each layer 14a, 14b, 14c is formed of a strictly different material or film thickness from the corresponding layer 4a, 4b, 4c, but has the same function. The cover layer 5 is formed on the L0 layer using a resin material. Even in this optical recording medium 11, the recording layers 4 and 14 need to be initialized during the manufacturing process. In this case, as shown in FIG. 7, after forming the power bar layer 5 in the same manner as in the optical recording medium 1, the objective lens 21 having the same numerical aperture NA as that used when the optical recording medium 1 is initialized is used. To initialize. Specifically, the L1 layer including the recording layer 4 is initialized by irradiating the L1 layer from the side of the cover layer 5 with the initialization laser beam LIN, and then, as shown in FIG. The L0 layer is initialized by irradiating the L0 layer with the beam LIN. Thus, the manufacture of the optical recording medium 11 in which the L1 layer and the LO layer have been initialized is completed. Disclosure of the invention

As a result of studying the method of initializing the above-described multilayer recording layer type optical recording medium, the inventors have found the following points to be improved. That is, in this initialization method, as shown in FIG. 7, when the L 0 layer formed on the spacer layer 12 is initialized, the initialization laser beam L IN applied to the LO layer is used. A part of the laser beam LPE passes through the L 0 layer and the spacer layer 12 to reach the L 1 layer, and a part of the laser beam LRE of the laser beam LPE is reflected by the L 1 layer. In this case, interference occurs due to unevenness in the thickness of the spacer layer 12 between the reflected laser beam LRE and the laser beam LIN applied to the L0 layer. For this reason, the amount of light absorbed by the L O layer is partially different, and as a result, the calorific value differs for each part of the L 0 layer (heat generation unevenness occurs in the L 0 layer). Therefore, due to the re-irradiation of the reflected laser beam LRE, the crystal state of the L0 layer, particularly the phase change material layer 14b in the recording layer 14, becomes uneven, and the L0 layer is initialized well. This may not be done, and it is preferable to improve this point.

The present invention has been made in view of the above points to be improved, and has as its main object to provide a method of initializing a multilayer recording layer type optical recording medium capable of uniformly initializing each layer including a recording layer. And Also, a multilayer recording layer capable of uniformly initializing each layer including the recording layer. It is another main object to provide an apparatus for initializing a type optical recording medium.

The method for initializing a multilayer recording layer type optical recording medium according to the present invention comprises a plurality of layers LN, L (N-1),..., L2 each including a recording layer which is initialized by light irradiation. , L

The plurality of layers in a multilayer recording layer type optical recording medium in which 1, LO (N is an integer of 1 or more) are laminated in this order on one surface side of a base material and a spacer layer is formed between the respective layers. For one of the layers LM (N≥M≥1), when the thickness of the spacer layer adjacent to the surface on the substrate side in the layer LM is defined as TH (μιη), Is initialized by irradiating light from the layer L0 side using an objective lens having a numerical aperture NA (Numerical Aperture) that satisfies the following conditions.

THXNA≥ 9

The apparatus for initializing a multilayer recording layer type optical recording medium according to the present invention includes a plurality of layers LN, L (N-1),..., Each including a recording layer initialized by light irradiation. L2, L1, L0 (N is an integer of 1 or more) are laminated in this order on one surface side of a substrate, and a spacer layer is formed between the respective layers. Of the multilayer recording layer type optical recording medium including an objective lens for irradiating one of the plurality of layers LM (N≥M≥1) with light from the layer L0 side and initializing the same. Wherein the objective lens has a numerical aperture NA that satisfies the following equation when the thickness of the spacer layer adjacent to the surface of the layer LM on the substrate side is TH (μηι). It is stipulated and configured.

THXNA≥ 9

According to the initialization method and the initialization apparatus for the multilayer recording layer type optical recording medium, when the layer LM is initialized, the thickness of the spacer layer adjacent to the substrate side surface of the layer LM is set to TH (μνη) By using an objective lens with a numerical aperture を満たすを満たす that satisfies the equation (ΤΗΧΝΑ≥9), the layer L 0 is irradiated with light to initialize the layer, and the layer adjacent to the spacer layer is sandwiched. Since the influence of the reflected light from L (M + 1) can be reduced, the inside of the layer LM can be initialized uniformly. Therefore, a reliable initialized A layer recording layer type optical recording medium can be manufactured.

The method for initializing a multilayer recording layer type optical recording medium according to the present invention includes a plurality of layers LN, L (N-1),..., L2, L2 each including a recording layer initialized by light irradiation.

1, LO (N is an integer of 1 or more) is laminated on one surface side of the base material in this order, and a spacer layer is formed between the layers. One of the layers LM (N≥M≥1) is initialized by irradiating light from the layer L0 side with an objective lens having a numerical aperture NA of 0.55 or more.

The apparatus for initializing a multilayer recording layer type optical recording medium according to the present invention includes a plurality of layers LN, L (N-1),..., Each including a recording layer initialized by light irradiation. L2, L1, L0 (N is an integer of 1 or more) are laminated in this order on one surface side of a base material, and a spacer layer is formed between the respective layers. Initialization of a multilayer recording layer type optical recording medium including an objective lens for irradiating one layer LM (N≥M≥1) of the plurality of layers from the layer L0 side and initializing the same. In the apparatus, the objective lens has a numerical aperture NA defined to have a value of 0.55 or more.

In the initialization method and the initialization apparatus for the multilayer recording layer type optical recording medium, when the layer LM is initialized, light is irradiated from the layer L0 side using an objective lens having a numerical aperture NA of 0.55 or more. Thus, the influence of the reflected light from the layer adjacent to the spacer layer can be reduced, so that the layer LM including the recording layer can be uniformly initialized. Therefore, a highly reliable initialized multi-layer recording layer type optical recording medium can be manufactured.

This disclosure relates to the subject matter included in Japanese Patent Application No. 2001-316126 filed on October 15, 2001, and all of these disclosures are expressly incorporated herein by reference. Incorporated in BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an explanatory diagram for explaining an initialization method for initializing the optical recording medium 11 on which the L1 layer and the L0 layer are formed.

FIG. 2 is a configuration diagram showing a configuration of an initialization apparatus M for initializing the optical recording medium 11 on which the L1 layer and the L0 layer are formed.

FIG. 3 is a diagram showing experimental results when the initialization of the L0 layer was confirmed using various objective lenses having different numerical apertures NA.

FIG. 4 is an explanatory diagram for explaining an initialization method for initializing the optical recording medium 41 on which the L2 layer, the L1 layer, and the L0 layer are formed.

FIG. 5 is a cross-sectional view showing a schematic configuration of the optical recording medium 1 on which one recording layer 4 is formed.

FIG. 6 is a cross-sectional view showing a schematic configuration of the optical recording medium 11 on which the L1 layer and the L0 layer are formed.

FIG. 7 is an explanatory diagram for explaining an initialization method that is already performed by the inventor when initializing the optical recording medium 11 on which the L1 layer and the L0 layer are formed. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of a method for initializing a multilayer recording layer type optical recording medium according to the present invention will be described with reference to the accompanying drawings. Note that components having the same structure as the above-described optical recording media 1 and 11 are denoted by the same reference numerals, and redundant description will be omitted. As shown in FIGS. 1 and 6, the optical recording medium 11 in which the recording layer is initialized by the method for initializing a multilayer recording layer type optical recording medium according to the present invention has a fine uneven surface on the base material 2 (see FIG. On the (upper surface in the figure) side, an L 1 layer, a spacer layer 12, an L 0 layer adjacent to the spacer layer 12, and a cover layer 5 are sequentially laminated.

Next, an initialization device M for the optical recording medium 11 according to the present invention will be described with reference to FIG.

Initializer M is a spindle motor MT, pickup PU, spindle server It has SPS, feed servo TR S, focus tracking servo FTS, and control unit CNT. In this case, the spindle motor MT is driven and controlled by a spindle servo SPS as described later, and rotates the optical recording medium 11 at a constant linear velocity.

The pickup PU has a laser emitting section and a laser receiving section integrated with each other, and a laser (not shown) is driven by a laser driver under the control of the control section CNT, and the optical recording medium 11 The laser beam LIN set to the initialization power is emitted to the optical recording medium 11. Further, the pickup PU includes an objective lens 31 and a half mirror (not shown), and focuses the initialization laser beam L IN on the L 1 layer and the L 0 layer of the optical recording medium 11. Specifically, the objective lens 31 is subjected to focus tracking control by the focus tracking servo FTS, whereby the initialization laser beam LIN is focused on the L1 and L0 layers of the optical recording medium 11. Can be In this case, when the thickness of the spacer layer 12 in the optical recording medium 11 is defined as TH (μτη), the objective lens 31 is configured to have a numerical aperture を満たす that satisfies the following equation (1). ing.

ΤΗΧΝΑ≥ 9 (1)

Generally, the thickness ΤΗ of the spacer layer 12 is set to about 20 μπι, as described above, and at least 16.5 μπι or more. Therefore, even when the spacer layer 12 is formed as the objective lens 31 with a thickness of, for example, 16.5 μη, the numerical aperture ΝΑ has a value of 0.5 so as to satisfy the above equation (1). Use 5 types. When the spacer layer 12 is formed with a small thickness of 13 μηι, a type having a numerical aperture ΝΑ of 0.7 to satisfy the above equation (1) is used. The pickup U is reciprocated by a feed servo TRS between the inner peripheral side and the outer peripheral side thereof along the diameter direction of the optical recording medium 11.

The spindle servo SPS controls the rotation of the spindle motor よう such that the linear velocity of the optical recording medium 11 becomes constant under the control of the control unit C Ν Τ. Control unit C NT Controls the drive of the pickup PU, the spindle servo SPS, the feed servo TRS, and the focus tracking servo FTS.

Next, a method of initializing the optical recording medium 11 will be described with reference to FIG. Note that the method of manufacturing the optical recording medium 11 except for initialization is manufactured according to the above-described manufacturing method, and a description thereof will be omitted.

First, the control unit CNT controls the spindle servo SPS to drive the spindle motor MT, and rotates the optical recording medium 11 so that the linear velocity becomes constant. Next, the control unit CNT moves the pickup PU to the initialization start position by controlling the feed servo TRS, and controls the focus tracking servo FTS to control the optical recording medium 11. Position the objective lens 31 so that the focal position matches the L1 layer. After that, the control unit CNT controls the feed servo TRS and the focus tracking servo FTS, thereby moving the pickup PU from, for example, the inner circumference to the outer circumference, and performing an initializing laser beam to perform IN. The L1 layer including the recording layer 4 is first initialized by irradiating the L1 layer from the cover layer 5 side.

Next, the control unit CNT positions the objective lens 31 so that its focal position coincides with the L0 layer, and then irradiates the initialization laser beam LIN to the LO layer, as in the case of the L1 layer. Then, the L0 layer including the recording layer 14 is initialized. At this time, as shown in Fig. 1, an objective lens 21 with a numerical aperture NA of 0.34 was used for a part of the initialization laser beam L IN irradiated to the L0 layer, as shown in Fig. 1. As before, it passes through the L0 layer and the spacer layer 12 to reach the L1 layer. Then, a part of the laser beam LRE of the laser beam LPE that has reached the L 1 layer is reflected by the L 1 layer (in particular, the reflective layer 3 in the L 1 layer) to irradiate the L 0 layer. In this case, the spot diameter DI of the laser beam LRE irradiating the L0 layer is the spot diameter DI when the objective lens 21 is used because the numerical aperture NA of the objective lens 31 is larger than the numerical aperture NA of the objective lens 21. (See Figures 1 and 7). I mean The laser beam LRE reflected by the L1 layer when the objective lens 31 is used is sufficiently diffused.

Therefore, when the laser beam of the initialization laser beam L IN is specified to be a constant value, when the L 0 layer is initialized, it is reflected by the L 1 layer and irradiates the L 0 layer per unit area. The irradiation amount of the laser beam LRE is sufficiently lower than the irradiation amount of the laser beam LRE per unit area when the objective lens 21 is used. As a result, at the time of initialization using the objective lens 31, the above description was made between the laser beam L RE reflected by the L 1 layer and the initialization laser beam L IN irradiated to the L 0 layer. The interference caused by the unevenness of the thickness of the spacer layer 12 occurs, but the irradiation energy of the laser beam L RE is diffused and sufficiently reduced, so that the amount of light absorbed by the L 0 layer is partially different. Phenomenon does not occur. As a result, it is possible to avoid the occurrence of unevenness in the crystallization state due to the re-irradiation of the laser beam LRE to the already initialized portion of the L 0 layer. There is a monkey.

The inventor has specified the thickness TH of the spacer layer 12 to be a constant value (20 μπι) and used various objective lenses having different numerical apertures の to initialize the L 0 layer. Pass / fail was confirmed. Figure 3 shows the results of this experiment. According to the results of this experiment, it was confirmed that when the numerical aperture Ν 初期 was initialized using an objective lens having a value of 0.45 or less, all of the initialized states were defective. On the other hand, it was confirmed that when the objective lens was initialized using an objective lens having a numerical aperture NA of 0.55 or more, all the initialized states were good. Therefore, as long as the numerical aperture NA of the objective lens is set to a value of 0.55 or more, the L0 layer including the recording layer 14 and the L1 layer including the recording layer 4 can always be properly initialized. Also, considering that the thickness TH of the spacer layer 12 is specified to be at least 16.5 inches or more, as long as the numerical aperture NA of the objective lens is set to a value of 0.55 or more, the above value is always set. Equation (1) holds. Therefore, when the optical recording medium 11 is initialized, as long as an objective lens with a numerical aperture NA of 0.55 or more is used, L 1 The layer and the L0 layer can be satisfactorily initialized, and as a result, a highly-reliable initialized multilayer recording layer type optical recording medium can be manufactured. Also, considering that the spacer layer 12 is formed with a small thickness of 13 / ζπι, the above equation (1) is satisfied as long as the type having a numerical aperture NA of 0.7 is used. As long as an objective lens having a numerical aperture NA of 0.7 or more is used, the L1 layer and the L0 layer can always be properly initialized.

As described above, according to the initialization method and the initialization apparatus, the L0 layer is initialized using the objective lens 31 having a numerical aperture NA of 0.55, so that the lower layer than the L0 layer is formed. It is possible to avoid the occurrence of the initialization unevenness due to the reflection of the initialization laser beam L IN by the L 1 layer located in the (layer far from the incident light). Therefore, the light having the reflective layer 3 formed on one surface side of the base material 2 and the one layer and the L 0 layer formed as the upper layer of the reflective layer 3 with respect to the irradiation direction of the initialization laser beam L IN. When the recording medium 11 is initialized, the crystallization state of the L 0 layer (particularly, the phase change material layer 4 b) can be made uniform, so that the L 0 layer as the upper layer of the L 1 layer can be reliably and reliably formed. It can be initialized well.

It should be noted that the present invention is not limited to the above-described embodiment of the invention, but can be appropriately modified. For example, as shown in FIG. 4, three or more layers having a recording layer were formed (for example, L0 and L1 layers each having a recording layer 14 and L2 layer having a recording layer 4). The present invention can also be applied to the initialization of the L0 layer and the L1 layer in the optical recording medium 41. In this case, the optical recording medium 41 is provided on one surface side of the base material 2 with an L2 layer having the same structure as the L1 layer in the optical recording medium 11 and a spacer layer 12 having a thickness of TH (hereinafter, referred to as “lower layer”). Layer 1 2) of the optical recording medium 11 adjacent to the spacer layer 12 and having substantially the same structure as the L 0 layer of the optical recording medium 11, and substantially the same as the lower spacer layer 12. A spacer layer 12 having the same structure, an L 0 layer adjacent to the spacer layer 12 and having substantially the same structure as the L 1 layer, and a cover layer 5 are stacked in this order.

When the optical recording medium 41 is initialized, the thickness TH of the lower spacer layer 12 must be On the other hand, an objective lens 51 with a numerical aperture NA satisfying the above equation (1) is used. At this time, the laser beam LIN for initialization is irradiated in order of the L2 layer, the L1 layer, and the L0 layer, and the L2 layer including the recording layer 4, the L1 layer including the recording layer 14, and the recording layer 14 are irradiated. Are sequentially initialized. When each spacer layer 12 is formed with a thickness 16. of at least 16.5 μπι, an objective lens having a numerical aperture がが that satisfies the above equation (1) and a value of 0.55 or more is always used. Used for lens 51.

According to this initialization method, as shown in FIG. 4, when the L1 layer is initialized, the spot diameter DI of the laser beam LRE that is reflected by the L2 layer and irradiates the L1 layer can be increased. The irradiation amount per unit area of the laser beam LRE to the L1 layer can be sufficiently reduced. Therefore, the crystallization state of the L 1 layer (particularly, the phase change material layer 14 b in the L 1 layer) can be made uniform, so that the L 1 layer as the upper layer of the L 2 layer can be reliably and well initialized. be able to. When the L0 layer is initialized, the spot diameter DI of the laser beam LRE which irradiates the L0 layer by being reflected by the L2 layer (in particular, the reflective layer 3 in the L2 layer) is set to be the initial value for the L1 layer. It will be even more widespread than in the case of a period. Therefore, the influence of the laser beam LRE irradiation on the already initialized portion in the L0 layer is further reduced than when the L1 layer is initialized. Therefore, the L0 layer can be more properly initialized. Furthermore, when the L0 layer is initialized, the thickness TH of each spacer layer 12, 12 is the same even if some of the laser beam LPE passing through the L0 layer is reflected by the L1 layer. Then, the above expression (1) is satisfied. As a result, the L0 layer can be satisfactorily initialized without being affected by the laser beam LRE reflected by the L1 layer. As a result, a highly-reliable initialized multilayer recording layer type optical recording medium is obtained. Can be manufactured. Industrial applicability

As described above, the method for initializing the multilayer recording layer type optical recording medium according to the present invention and the method for According to the apparatus for initializing a layer recording layer type optical recording medium, when the thickness of the spacer layer adjacent to the substrate-side surface of this layer LM is set to TH (μπι) when the layer LM is initialized, By initializing by irradiating light from the layer L0 side using an objective lens with a numerical aperture を満たす that satisfies the formula (ΤΗΧΝΑ≥9), the layer L (Μ + 1) adjacent to the spacer layer Since the influence of the reflected light from the LM can be reduced, the inside of the layer LM can be initialized uniformly. Therefore, it is possible to manufacture a highly-reliable initialized multilayer recording layer type optical recording medium. Therefore, an initialization method of a multilayer recording layer type optical recording medium and an initialization apparatus of a multilayer recording layer type optical recording medium which can uniformly initialize each layer including a recording layer are realized.

Claims

The scope of the claims

1. Plural layers LN, L (N-1),--, L2, LI, LO (N is an integer of 1 or more) each including a recording layer initialized by light irradiation With respect to one layer LM (N≥M≥1) of the plurality of layers in a multilayer recording layer type optical recording medium in which the layers are stacked in this order and a spacer layer is formed between the respective layers. When the thickness of the spacer layer adjacent to the surface on the base material side of the layer LM is TH (/ zm), the objective lens having a numerical aperture NA that satisfies the following equation is used. Initialization method of a multilayer recording layer type optical recording medium which is initialized by irradiating light.

THXNA≥ 9

2. Multiple layers LN, L (including the recording layer initialized by light irradiation)

N-1),--·, L2, LI, LO (N is an integer of 1 or more) are laminated in this order on one side of the base material, and a spacer layer is formed between the layers. With respect to one layer LM (N≥M≥1) of the plurality of layers in the multilayer recording layer type optical recording medium, the layer L is formed using an objective lens having an aperture NA of 0.55 or more. A method for initializing a multilayer recording layer type optical recording medium which is initialized by irradiating light from the 0 side.

3. Multiple layers LN, L (N-1),--, L2, LI, LO (N is an integer of 1 or more) each including the recording layer initialized by light irradiation With respect to one layer LM (N≥M≥1) of the plurality of layers in a multilayer recording layer type optical recording medium in which the layers are stacked in this order and a spacer layer is formed between the respective layers. An apparatus for initializing a multilayer recording layer type optical recording medium comprising an objective lens for initializing by irradiating light from the layer L0 side,

The objective lens has a numerical aperture を満たす that satisfies the following equation when the thickness of the spacer layer adjacent to the surface of the layer LM on the substrate side is TH (μτη).

V. Initializer for multilayer recording layer type optical recording medium.

ΤΗΧΝΑ≥ 9

4. Multiple layers LN, L (including the recording layer initialized by light irradiation) N-1), · · ·, L2, LI, L0 (N is an integer of 1 or more) are stacked in this order on one side of the base material, and a spacer layer is formed between the respective layers. An objective lens for irradiating one of the plurality of layers LM (N≥M≥1) of the plurality of layers in the multi-layered recording medium with light from the layer L0 side to initialize the layer. An apparatus for initializing a multilayer recording optical recording medium, comprising:

An initialization apparatus for a multilayer recording layer type optical recording medium, wherein the objective lens has a numerical aperture NA of not less than 0.55.