JP2005108396A - Write once type optical recording medium and its recording and reproduction method - Google Patents
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Abstract
Description
本発明は、追記型(WORM:Write Once Read Many)光記録媒体に係り、特に青色レーザ波長領域でも高密度の記録が可能な追記型光記録媒体に関する。 The present invention relates to a write once read many (WORM) optical recording medium, and more particularly to a write once optical recording medium capable of high density recording even in a blue laser wavelength region.
1. 青色レーザ波長以下で記録再生が可能な追記型光記録媒体に関して
超高密度の記録が可能となる青色レーザの開発は急速に進んでおり、それに対応した追記型光記録媒体の開発が行われている。
従来の追記型光記録媒体では、有機材料からなる記録層にレーザ光を照射し、主に有機材料の分解・変質による屈折率変化を生じさせることで記録ピットを形成させており、記録層に用いられる有機材料の光学定数や分解挙動が、良好な記録ピットを形成させるための重要な要素となっている。
従って、青色レーザ対応の追記型光記録媒体の記録層に用いる有機材料としては、青色レーザ波長に対する光学的性質や分解挙動の適切な材料を選択する必要がある。即ち、未記録時の反射率を高め、またレーザの照射によって有機材料が分解し大きな屈折率変化が生じるようにするため(これによって大きな変調度が得られる)、記録再生波長は大きな吸収帯の長波長側の裾に位置するように選択される。何故ならば、有機材料の大きな吸収帯の長波長側の裾は、適度な吸収係数を有し且つ大きな屈折率が得られる波長領域となるためである(図1参照。従来の有機材料を記録層とした追記型光記録媒体では、図中の斜線部分に記録再生波長を設定する)。
1. Write-once type optical recording media capable of recording / reproducing below the wavelength of the blue laser The development of blue lasers capable of ultra-high-density recording is progressing rapidly, and the development of write-once type optical recording media corresponding to it has been carried out. Yes.
In conventional write-once optical recording media, recording pits are formed by irradiating a recording layer made of an organic material with laser light and causing a change in refractive index mainly due to decomposition and alteration of the organic material. The optical constant and decomposition behavior of the organic material used are important factors for forming good recording pits.
Therefore, it is necessary to select an organic material used for the recording layer of the write-once type optical recording medium compatible with blue laser, which has an appropriate optical property and decomposition behavior with respect to the blue laser wavelength. In other words, the recording / reproducing wavelength has a large absorption band in order to increase the reflectivity when unrecorded, and to cause a large change in refractive index due to decomposition of the organic material by laser irradiation (this provides a large degree of modulation). It is selected so as to be located at the bottom of the long wavelength side. This is because the long wavelength side skirt of the large absorption band of the organic material is a wavelength region having an appropriate absorption coefficient and a large refractive index (see FIG. 1. Recording conventional organic materials) In a recordable optical recording medium having a layer, a recording / reproducing wavelength is set in a hatched portion in the figure).
しかしながら、青色レーザ波長に対する光学的性質が従来並みの値を有する有機材料は未だ見出されていない。これは、青色レーザ波長近傍に吸収帯を持つ有機材料を得るためには、分子骨格を小さくするか又は共役系を短くする必要があるが、そうすると吸収係数の低下、即ち屈折率の低下を招くためである。
つまり、青色レーザ波長近傍に吸収帯を持つ有機材料は多数存在し、吸収係数を制御することは可能となるが、大きな屈折率を持たないため、大きな変調度を得ることができなくなる。
また、従来の追記型光記録媒体では、有機材料の分解・変質による屈折率変化と共に、基板変形によっても記録が行われている。例えば、図3〔市販のDVD−Rに記録を行った部分の基板面をAFM(アトミックフォースマイクロスコープ、Atomic force microscope)により観察した図〕に示すように、基板は反射層側に変形しており、この変形によって変調度を発生させている。
However, an organic material having an optical property with respect to a blue laser wavelength that is the same as the conventional value has not yet been found. In order to obtain an organic material having an absorption band in the vicinity of the blue laser wavelength, it is necessary to reduce the molecular skeleton or shorten the conjugated system, but this leads to a decrease in absorption coefficient, that is, a decrease in refractive index. Because.
That is, there are many organic materials having an absorption band near the blue laser wavelength, and the absorption coefficient can be controlled. However, since there is no large refractive index, a large degree of modulation cannot be obtained.
Further, in the conventional write-once type optical recording medium, recording is performed by deformation of the substrate as well as a change in refractive index due to decomposition and alteration of the organic material. For example, as shown in FIG. 3 [the surface of the substrate recorded on a commercially available DVD-R observed with an AFM (Atomic Force Microscope)], the substrate is deformed to the reflective layer side. The degree of modulation is generated by this deformation.
青色レーザ対応の有機材料としては、例えば、特許文献1〜5に記載がある。
しかし、これらの公報では、実施例を見ても溶液と薄膜のスペクトルを測定しているのみで、記録再生に関する記載はない。
特許文献6〜8では、実施例に記録の記載があるものの、記録波長は488nmであり、また記録条件や記録密度に関する記載はなく、良好な記録ピットが形成できた旨の記載があるのみである。
特許文献9では、実施例に記録の記載があるものの、記録波長は430nmであり、また記録条件や記録密度に関する記載はなく、良好な変調度が得られた旨の記載があるのみである。
特許文献10〜19では、実施例に記録波長430nm、NA0.65での記録例があるが、最短ピットが0.4μmという低記録密度条件(DVDと同等の記録密度)である。
特許文献20では、記録再生波長は405〜408nmであるが、記録密度に関する具体的な記載がなく、14T−EFM信号の記録という低記録密度条件である。
For example, Patent Documents 1 to 5 describe organic materials for blue lasers.
However, these publications only measure the spectra of the solution and the thin film even when looking at the examples, and there is no description regarding recording and reproduction.
In Patent Documents 6 to 8, although there is a description of recording in the examples, the recording wavelength is 488 nm, there is no description about recording conditions and recording density, and there is only a description that good recording pits can be formed. is there.
In Patent Document 9, although there is a description of recording in the examples, the recording wavelength is 430 nm, there is no description regarding recording conditions and recording density, and there is only a description that a good modulation degree is obtained.
In Patent Documents 10 to 19, there is a recording example with a recording wavelength of 430 nm and NA of 0.65 in Examples, but the low recording density condition (the recording density equivalent to DVD) is that the shortest pit is 0.4 μm.
In Patent Document 20, the recording / reproducing wavelength is 405 to 408 nm, but there is no specific description about the recording density, and the recording density is a low recording density condition of recording a 14T-EFM signal.
以上の特許文献で開示されている有機材料は、現在実用化されている青色半導体レーザの発振波長の中心である405nm近傍において、従来の追記型光記録媒体の記録層に要求される光学定数と同程度の光学定数を有する材料ではない。また、405nm近傍で記録条件を明確にし、DVDよりも高記録密度で記録された実施例がないため、実際に15〜25GBといったような高密度の記録が行えるかどうか不明である。更に、上記公知技術における実施例の多くは、従来のディスク構成(基板/有機材料層/反射層)での実験であり、そこに用いられる色素は従来と同じ光学特性と機能が要求されている。
従来の有機材料を用いた追記型光記録媒体では、変調度と反射率の確保の点から、記録再生波長に対し大きな屈折率と比較的小さな吸収係数(0.05〜0.07程度)を持つ有機材料しか使用することができない。
The organic materials disclosed in the above patent documents have optical constants required for a recording layer of a conventional write-once optical recording medium in the vicinity of 405 nm, which is the center of the oscillation wavelength of a blue semiconductor laser currently in practical use. It is not a material having the same optical constant. In addition, since there is no example in which recording conditions are clarified in the vicinity of 405 nm and recording is performed at a higher recording density than DVD, it is unclear whether high-density recording such as 15 to 25 GB can actually be performed. Furthermore, many of the examples in the above-mentioned known art are experiments in a conventional disk configuration (substrate / organic material layer / reflection layer), and the dyes used therein are required to have the same optical characteristics and functions as in the past. .
A conventional write-once optical recording medium using an organic material has a large refractive index and a relatively small absorption coefficient (about 0.05 to 0.07) with respect to the recording / reproducing wavelength from the viewpoint of securing the degree of modulation and the reflectance. You can only use organic materials that you have.
従って、従来の有機材料を用いた追記型光記録媒体では、記録再生波長近傍に有機材料の主吸収帯が存在するため、図2に示すように、有機材料の光学定数の波長依存性が大きくなり(波長によって光学定数が大きく変動する)、レーザの個体差や環境温度の変化等による記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等が大きく変化するという問題があった。
更に、有機材料は記録光に対して十分な吸収能を持たないため、有機材料の膜厚を薄膜化することが不可能であり、従って、深い溝を持った基板を使用する必要があった(有機材料は通常スピンコート法によって形成されるため、有機材料を深い溝に埋めて厚膜化している)。そのため、深い溝を有する基板の形成が非常に難しくなり、光記録媒体としての品質を低下させる要因になっている。
また、有機材料の膜厚を薄くすることができないため、記録パワーマージン等が狭くなるといった問題点(記録再生特性の各種マージンが狭いという問題)を有していた。
Therefore, in a write-once type optical recording medium using a conventional organic material, the main absorption band of the organic material exists in the vicinity of the recording / reproducing wavelength, so that the wavelength dependence of the optical constant of the organic material is large as shown in FIG. (Optical constants vary greatly depending on the wavelength), recording characteristics such as recording sensitivity, modulation factor, jitter, error rate, and reflectivity for recording / reproducing wavelength fluctuations due to individual differences in lasers and environmental temperature changes There was a problem that etc. changed greatly.
Furthermore, since the organic material does not have sufficient absorption capability for recording light, it is impossible to reduce the film thickness of the organic material, and thus it is necessary to use a substrate having a deep groove. (Organic materials are usually formed by spin coating, so they are thickened by burying them in deep grooves). Therefore, it becomes very difficult to form a substrate having a deep groove, which is a factor of deteriorating the quality as an optical recording medium.
In addition, since the film thickness of the organic material cannot be reduced, there is a problem that the recording power margin and the like are narrowed (the problem that various margins of the recording / reproducing characteristics are narrow).
また、従来のCD、DVD系光記録媒体と異なる層構成及び記録方法に関して、以下のような技術が公開されている。
特許文献21には、基板/可飽和吸収色素含有層/反射層という層構成で、可飽和吸収色素の消衰係数(本発明でいう吸収係数)の変化により記録を行う技術が開示されている。
特許文献22には、基板/金属蒸着層/光吸収層/保護シ−トという層構成で、光吸収層によって発生した熱によって、金属蒸着層を変色又は変形させることで記録を行う技術が開示されている。
特許文献23には、基板/誘電体層/光吸収体を含む記録層/反射層という層構成で、記録層の膜厚を変えることにより溝部の深さを変えて記録を行う技術が開示されている。
特許文献24には、基板/光吸収体を含む記録層/金属反射層という層構成で、記録層の膜厚を10〜30%変化させることにより記録を行う技術が開示されている。
特許文献25には、基板/有機色素を含有する記録層/金属反射層/保護層という層構成で、基板の溝幅を未記録部に対して20〜40%広くすることにより記録を行う技術が開示されている。
Further, the following technologies are disclosed regarding the layer configuration and recording method different from those of conventional CD and DVD optical recording media.
Patent Document 21 discloses a technique for recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a layer structure of substrate / saturable absorbing dye-containing layer / reflective layer. .
Patent Document 22 discloses a technique for recording by changing the color or deformation of a metal vapor deposition layer by heat generated by the light absorption layer in a layer configuration of substrate / metal vapor deposition layer / light absorption layer / protective sheet. Has been.
Patent Document 23 discloses a technique for recording by changing the depth of the groove portion by changing the film thickness of the recording layer in the layer configuration of substrate / dielectric layer / recording layer including light absorber / reflective layer. ing.
Patent Document 24 discloses a technique for performing recording by changing the film thickness of the recording layer by 10 to 30% in a layer configuration of substrate / recording layer including light absorber / metal reflective layer.
Patent Document 25 discloses a technique for recording by increasing the groove width of a substrate by 20 to 40% with respect to an unrecorded portion in a layer configuration of substrate / recording layer containing organic dye / metal reflective layer / protective layer. Is disclosed.
特許文献26には、基板/中間層/金属薄膜という層構成で、金属薄膜が変形しバブルを形成することにより記録を行う技術が開示されている。
特許文献27には、基板/光吸収層/記録補助層/光反射層という層構成で、記録補助層を凹状に変形させると共に、記録補助層の変形に沿って光反射層を凹状に変形させることで記録を行う技術が開示されている。
特許文献28には、基板/光吸収層/多孔質な記録補助層/光反射層、或いは、基板/多孔質な記録補助層/光吸収層/光反射層という層構成で、記録補助層を凹状に変形させると共に、記録補助層の変形に沿って光反射層を凹状に変形させることで記録を行う技術が開示されている。
特許文献29には、基板/多孔質な光吸収層/光反射層という層構成で、光吸収層を凹状に変形させると共に、光吸収層の変形に沿って光反射層を凹状に変形させることで記録を行う技術が開示されている。
特許文献30には、基板/有機色素を含む記録層/記録補助層という層構成で、記録補助層と有機色素が相溶して、有機色素の吸収スペクトルを短波長側へシフトさせることで記録を行う技術が開示されている。
Patent Document 26 discloses a technique for recording by forming a bubble by deforming a metal thin film with a layer structure of substrate / intermediate layer / metal thin film.
In Patent Document 27, the recording auxiliary layer is deformed into a concave shape in a layer configuration of substrate / light absorption layer / recording auxiliary layer / light reflecting layer, and the light reflecting layer is deformed into a concave shape along with the deformation of the recording auxiliary layer. Thus, a technique for recording is disclosed.
In Patent Document 28, a recording auxiliary layer having a layer structure of substrate / light absorbing layer / porous recording auxiliary layer / light reflecting layer or substrate / porous recording auxiliary layer / light absorbing layer / light reflecting layer is provided. A technique is disclosed in which recording is performed by deforming into a concave shape and deforming the light reflecting layer into a concave shape along with the deformation of the recording auxiliary layer.
In Patent Document 29, the light absorption layer is deformed into a concave shape in a layer configuration of substrate / porous light absorption layer / light reflection layer, and the light reflection layer is deformed into a concave shape along with the deformation of the light absorption layer. A technique for recording with the above is disclosed.
In Patent Document 30, recording is performed by shifting the absorption spectrum of an organic dye to the short wavelength side in a layer structure of a substrate / recording layer containing an organic dye / recording auxiliary layer, in which the recording auxiliary layer and the organic dye are compatible. Techniques for performing are disclosed.
特許文献31には、基板上に反射層と記録層の機能を有する複合機能層、保護層を順次形成した層構成で、基板と複合機能層がバンプを形成することで記録を行う技術が開示されている。なお、複合機能層としては、ニッケル、クロム、チタン等の金属、又はそれらの合金との規定がある。
特許文献32には、基板上に金属薄膜層、変形可能な緩衝層、反射層、保護層を順次形成した層構成で、基板と金属薄膜層を変形させ、同時にこの変形部での緩衝層膜厚を薄くさせることで記録を行う技術が開示されている。なお、金属薄膜層としては、ニッケル、クロム、チタン等の金属、又はそれらの合金との規定がある。また、緩衝層としては、変形し易く適当な流動性を持つ樹脂が用いられ、変形を促進させるために色素を含有させても良いとの記載がある。
特許文献33には、基板上に金属薄膜層、緩衝層、反射層を順次積層した層構成で、基板と金属薄膜層を変形させ、同時にこの変形部での緩衝層膜厚と光学定数とを変化させることで記録を行う技術が開示されている。なお、金属薄膜層としては、ニッケル、クロム、チタン等の金属、又はそれらの合金が好ましいとの記載がある。また、緩衝層は色素と有機高分子の混合物からなり、記録再生波長近傍に大きな吸収帯を有する色素が用いられる。
Patent Document 31 discloses a technique in which recording is performed by forming bumps on a substrate and the composite functional layer in a layer configuration in which a composite functional layer having a function of a reflective layer and a recording layer and a protective layer are sequentially formed on the substrate. Has been. In addition, as a composite functional layer, there exists a prescription | regulation with metals, such as nickel, chromium, titanium, or those alloys.
In Patent Document 32, a metal thin film layer, a deformable buffer layer, a reflective layer, and a protective layer are sequentially formed on a substrate, and the substrate and the metal thin film layer are deformed at the same time. A technique for recording by reducing the thickness is disclosed. In addition, as a metal thin film layer, there exists prescription | regulation with metals, such as nickel, chromium, titanium, or those alloys. In addition, as the buffer layer, there is a description that a resin that is easily deformable and has an appropriate fluidity is used, and a pigment may be contained in order to promote deformation.
In Patent Document 33, a metal thin film layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, and the substrate and the metal thin film layer are deformed. At the same time, the buffer layer thickness and the optical constant at the deformed portion are set. A technique for recording by changing is disclosed. In addition, as a metal thin film layer, there exists a description that metals, such as nickel, chromium, titanium, or those alloys are preferable. The buffer layer is made of a mixture of a dye and an organic polymer, and a dye having a large absorption band near the recording / reproducing wavelength is used.
特許文献34には、基板上に金属記録層、バッファ層、反射層を順次積層した層構成で、基板と金属記録層を変形させ、同時にこの変形部でのバッファ層膜厚と光学定数とを変化させることで記録を行う技術が開示されている。なお、金属記録層としては、ニッケル、クロム、チタン等の金属、又はそれらの合金が好ましいとの記載がある。また、バッファ層は色素と樹脂の混合物からなり、記録再生波長近傍に大きな吸収帯を有する色素が用いられる。
以上の公開技術は、基本的に青色レーザ波長領域での光記録媒体の実現を狙ったものではなく、青色レーザ波長領域で有効となる層構成や記録方法ではない。更に、上述の技術では、記録層中の色素に光吸収機能が必要となるため、色素の主吸収帯が記録再生波長近傍に存在しなければならず、色素の選択に大きな制限が加わる。
また、上述の技術では、その記録原理の主体が変形による場合が殆どである。この変形が記録原理の主体となると、良好なジッタや変調度が得られても、記録マーク間の干渉が大きくなるため、各種記録再生特性のマージンが狭くなるという問題がある。
In Patent Document 34, a metal recording layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, and the substrate and the metal recording layer are deformed. At the same time, the buffer layer thickness and the optical constant at the deformed portion are set. A technique for recording by changing is disclosed. In addition, as a metal recording layer, there exists a description that metals, such as nickel, chromium, titanium, or those alloys are preferable. The buffer layer is made of a mixture of a dye and a resin, and a dye having a large absorption band near the recording / reproducing wavelength is used.
The above disclosed technology is not basically aimed at realizing an optical recording medium in the blue laser wavelength region, and is not a layer configuration or a recording method effective in the blue laser wavelength region. Furthermore, in the above-described technique, since the dye in the recording layer needs to have a light absorption function, the main absorption band of the dye must exist in the vicinity of the recording / reproducing wavelength, which greatly restricts the selection of the dye.
In the above-described techniques, the main subject of the recording principle is mostly due to deformation. If this deformation becomes the main component of the recording principle, there is a problem that even if a good jitter and modulation degree are obtained, the interference between recording marks increases, and the margin of various recording / reproducing characteristics becomes narrow.
2. 多値記録が可能な追記型光記録媒体について
近年、記録容量の増大を目的に多値記録技術が開発されている。最近はホームユーザーでも普通に容量の大きいオーディオデータや画像/動画データを扱うようになり、また一方、ハードディスクも大容量化が進み、CDやDVD系の光記録媒体では記録容量が足りなくなってきている。
そんな中で、従来型の光記録媒体の容量を高める記録方式として、「多値記録技術(Multi Level Technology)」が、米国のベンチャー企業カリメトリクス社(Calimetrics, Inc.)から提案されている。この多値記録技術は、簡単に言えば、記録線密度を向上させるものである。
従来のCDやDVD系の光記録媒体では、記録するデータ列に応じて各記録マーク端部の位置や長さを変えて記録し、再生時に記録マークの長さを判定している(スライス方式)。簡単に現行のスライス方式について説明する。
2. Write-once type optical recording medium capable of multi-value recording In recent years, multi-value recording technology has been developed for the purpose of increasing the recording capacity. Recently, even home users have been handling audio data and image / video data with a large capacity. On the other hand, the capacity of hard disks has been increasing, and the recording capacity of CD and DVD optical recording media has become insufficient. Yes.
Under such circumstances, as a recording method for increasing the capacity of a conventional optical recording medium, “Multi Level Technology” has been proposed by a US venture company, Calimetrics, Inc. In short, this multi-value recording technique improves the recording linear density.
In conventional CD and DVD optical recording media, recording is performed by changing the position and length of the end of each recording mark according to the data string to be recorded, and the length of the recording mark is determined during reproduction (slice method). ). The current slice method will be briefly described.
図4に示すように、まず記録すべき情報である記録データ(a)に対応した記録波形(b)を用いて、光記録媒体に記録マーク列(c)を形成させる。
その記録媒体に記録された記録マーク列(c)に再生光を照射して情報を再生すると、図(d)に示すような再生信号波形が得られる。
この再生信号波形は、(b)で示した記録波形のような矩形波とはならず鈍った波形になるため、再生信号波形を等化器で整形する(具体的には再生信号の高周波成分が増幅される)。
次いで、この等化波形(e)と閾値との交点を検出し、ウインドウ内で交点が検出されれば「1」、交点が検出されなければ「0」として二値データを出力する(f)。
そしてこの交点検出に得られた二値データ(f)をNRZ変換することによって(g)に示すような復号データを得ている。
As shown in FIG. 4, first, a recording mark row (c) is formed on an optical recording medium using a recording waveform (b) corresponding to recording data (a) which is information to be recorded.
When information is reproduced by irradiating the recording mark row (c) recorded on the recording medium with reproduction light, a reproduction signal waveform as shown in FIG.
Since this reproduced signal waveform is not a rectangular wave like the recording waveform shown in (b) but becomes a dull waveform, the reproduced signal waveform is shaped by an equalizer (specifically, a high frequency component of the reproduced signal). Is amplified).
Next, an intersection between the equalized waveform (e) and the threshold is detected, and binary data is output as “1” if an intersection is detected in the window, and “0” if no intersection is detected (f). .
The binary data (f) obtained for the intersection detection is subjected to NRZ conversion to obtain decoded data as shown in (g).
これに対して多値記録では、基本セルと呼ばれる固定長の領域内に、記録するマークの反射率の多値化で情報を表現する。即ち、従来のCDやDVD系の光記録媒体では、記録マークの有無で1ビットを表現しているが、多値記録では、記録マークの大きさを例えば8種類に変えて記録し、8つのレベルの異なる反射率として読出す(図5参照)。従って、1つの記録マークで3ビット分の情報を表わすことができるため、記録密度を高めることができる。
この多値記録では、通常、再生時のレーザー光のビームスポット径は、基本セル長よりも大きい。これによって、1つの記録マークで3ビット分の信号を表現することができるため、トラックピッチを詰めることなく、記録線密度を上げ、記録容量を増加させることができる。
On the other hand, in multi-level recording, information is expressed by multi-leveling of the reflectance of a mark to be recorded in a fixed-length area called a basic cell. That is, in a conventional CD or DVD optical recording medium, one bit is expressed by the presence or absence of a recording mark, but in multi-value recording, recording is performed by changing the size of the recording mark to, for example, eight types. Reading is performed as reflectivity having different levels (see FIG. 5). Therefore, since information for 3 bits can be expressed by one recording mark, the recording density can be increased.
In this multi-value recording, the beam spot diameter of the laser beam during reproduction is usually larger than the basic cell length. As a result, a signal for 3 bits can be expressed by one recording mark, so that the recording linear density can be increased and the recording capacity can be increased without reducing the track pitch.
この多値記録可能な追記型光記録媒体に関しては、特許文献35〜41等に記載がある。また、特許文献35には、有機色素からなる記録層を有する光記録媒体に多値記録を行うという概念、及び、該光記録媒体において記録層の深さ方向に多値記録を行うという概念が示されている。しかし、この文献では、赤色レーザ波長に対応した多値記録可能な追記型光記録媒体を想定しており、層構成や有機色素は従来のCDやDVD系の追記型光記録媒体と何ら変わるところがない。
上記特許文献36には、多値記録が可能な有機色素からなる記録層を有する光記録媒体において、基板のガラス転移点と反射率の熱伝導率を規定する発明が記載されている。
特許文献37には、多値記録が可能な有機色素からなる記録層を有する光記録媒体において、有機色素の熱分解特性を規定する発明が記載されている。
特許文献38〜39には、多値記録が可能なフタロシアニンやシアニン色素からなる記録層を有する光記録媒体において、波長、NA、グルーブ幅の関係を規定した発明が記載されている。
特許文献40には、多値記録が可能な有機色素からなる記録層を有する光記録媒体において、グルーブ上の記録層膜厚とグルーブ深さの関係を規定した発明が記載されている。
特許文献41には、多値記録が可能な有機色素からなる記録層を有する光記録媒体において、未記録時の反射率を40〜80%とする発明が記載されている。
The write-once type optical recording medium capable of multi-value recording is described in Patent Documents 35 to 41 and the like. Further, Patent Document 35 has a concept of performing multilevel recording on an optical recording medium having a recording layer made of an organic dye, and a concept of performing multilevel recording in the depth direction of the recording layer on the optical recording medium. It is shown. However, this document assumes a write-once type optical recording medium capable of multi-value recording corresponding to the red laser wavelength, and the layer configuration and organic dye are different from conventional CD and DVD type write-once optical recording media. Absent.
Patent Document 36 discloses an invention that defines the glass transition point of a substrate and the thermal conductivity of reflectance in an optical recording medium having a recording layer made of an organic dye capable of multilevel recording.
Patent Document 37 describes an invention that defines the thermal decomposition characteristics of an organic dye in an optical recording medium having a recording layer made of an organic dye capable of multilevel recording.
Patent Documents 38 to 39 describe an invention in which a relationship between wavelength, NA, and groove width is defined in an optical recording medium having a recording layer made of phthalocyanine or cyanine dye capable of multilevel recording.
Patent Document 40 describes an invention that defines the relationship between the recording layer thickness on the groove and the groove depth in an optical recording medium having a recording layer made of an organic dye capable of multi-value recording.
Patent Document 41 describes an invention in which an optical recording medium having a recording layer made of an organic dye capable of multilevel recording has a reflectance of 40 to 80% when not recorded.
ところで、多値記録では、従来の二値記録よりも高密度記録を実現させるため、大雑把に言えば基本セル長を従来の二値記録での最短マーク長と同程度に小さくしなければならない。つまり、多値記録における最短マークは二値記録の最短マークよりも非常に小さくなる(短くなる)。
即ち、従来の記録材料、層構成等のままで十分高密度化した多値記録が可能となるのであれば、これは従来の記録材料、層構成等のままでも最短マークを短くできることを意味するため、二値記録でも最短マーク長を短くして高密度化が図れることになる(実際通常の二値記録では、特別な記録再生方法等を利用しない限り現状以上に記録密度を高めることができない)。
従って、二値記録よりも十分高密度化した多値記録可能な追記型光記録媒体を実現させるためには、従来の記録材料、層構成等のままでは実現不可能であって、従来とは異なる記録材料や層構成が新たに必要になる筈である。
By the way, in multi-level recording, in order to realize higher-density recording than in conventional binary recording, roughly speaking, the basic cell length must be made as small as the shortest mark length in conventional binary recording. That is, the shortest mark in multilevel recording is much smaller (shorter) than the shortest mark in binary recording.
That is, if multi-level recording with sufficiently high density can be performed with the conventional recording material, layer structure, etc., this means that the shortest mark can be shortened even with the conventional recording material, layer structure, etc. Therefore, even in binary recording, the shortest mark length can be shortened to increase the density (in actual binary recording, the recording density cannot be increased beyond the current level unless a special recording / reproducing method or the like is used. ).
Therefore, in order to realize a write-once type optical recording medium capable of multi-level recording with a sufficiently higher density than binary recording, it cannot be realized with conventional recording materials, layer configurations, etc. Different recording materials and layer structures should be newly required.
しかし、上記公知技術では、記録層の膜厚や反射層材料等の微調整は行っているものの、殆ど従来の記録材料、層構成等のままで多値記録を行うものであるから、従来に比べて小さい記録マークが形成できるという訳ではなく(従来よりも格段に小さい記録マークが、高い再生信頼性で記録再生できる筈がない)、記録再生技術によって従来よりも短い記録マークを信頼性よく再生できるようにしたに過ぎず、単に記録再生方法の発明を追記型光記録媒体に適用したに過ぎない。
また、上記公知技術では変形を主体として記録マークが形成されている(前述した図3参照)。この変形は、記録マーク間の長さが十分長い場合(記録線密度が低い場合)、或いは多値レベルが記録されたセルの長さが再生光のビーム径以上に連続しない場合は特に問題はないが、記録線密度が高くなる場合、或いは多値レベルが記録されたセルの長さが再生光のビーム径以上の長さで連続する場合は、変形が干渉しあって、その干渉が線形でなくなる(線形から大きく外れる)。
However, in the above known technique, although the film thickness of the recording layer and the reflective layer material are finely adjusted, multi-value recording is performed with almost the same conventional recording material, layer configuration, etc. Compared to conventional recording marks, it does not mean that smaller recording marks can be formed (recording / reproduction is much less reliable than conventional recording marks). The recording / reproducing method is merely applied to a write-once optical recording medium.
Further, in the above known technique, a recording mark is formed mainly by deformation (see FIG. 3 described above). This deformation is particularly problematic when the length between the recording marks is sufficiently long (when the recording linear density is low), or when the length of the cell in which the multilevel level is recorded is not continuous beyond the beam diameter of the reproduction light. However, if the recording linear density is high, or if the length of the cell in which the multilevel level is recorded is longer than the beam diameter of the reproduction light, the deformation interferes and the interference is linear. (Not far from linear).
この干渉が線形であるとは、干渉後の変形形状が、例えば、図6に示すように、あるセルの変形量と次の隣接セルの変形量とのほぼ加算で表されることを意味する〔図6(a)は、連続する3つのセルに変形を主体とする記録マークを形成した様子を平面図として示し、(b)は干渉がない場合のそれぞれの記録マークの変形量を断面図として示したもので、(c)はその変形が加算された様子を示した図である〕。
図7は、3つの連続したセルに変形を主体とする記録マークを形成した場合であって、その記録されたセルの一連の長さが再生ビーム径以下の場合、3つのセルの変形の干渉の違いによる再生信号の変化を模式的に示したものである。変形の干渉が線形であれば図7(b)のような変形状態になるが、変形の干渉が線形でなくなると、図7(c)、(d)のような変形状態を示すようになる。
しかし、この干渉した変形が再生ビーム径以下の長さであるため、変形状態の違いを検出することができず、変形状態が(b)、(c)、(d)のように異なった場合でも、ほぼ(e)に示すような再生信号が得られる。
従って、(e)に示したT1、T2、T3のサンプリングタイムで反射レベルを検出すれば、正しいデータを復元することができる。
The fact that the interference is linear means that the deformed shape after the interference is expressed, for example, by substantially adding the deformation amount of a certain cell and the deformation amount of the next adjacent cell, as shown in FIG. [FIG. 6A is a plan view showing a state in which recording marks mainly composed of deformation are formed in three consecutive cells, and FIG. 6B is a sectional view showing the deformation amount of each recording mark when there is no interference. (C) is a diagram showing how the deformation is added].
FIG. 7 shows a case where a recording mark mainly composed of deformation is formed in three consecutive cells, and when the series of recorded cells has a length equal to or smaller than the reproduction beam diameter, the interference of the deformation of the three cells. The change of the reproduction signal due to the difference is schematically shown. If the deformation interference is linear, the deformation state is as shown in FIG. 7B. If the deformation interference is not linear, the deformation state is shown in FIGS. 7C and 7D. .
However, since the interfering deformation is not longer than the reproduction beam diameter, the difference in deformation state cannot be detected, and the deformation states are different as shown in (b), (c), (d). However, a reproduction signal almost as shown in (e) can be obtained.
Accordingly, if the reflection level is detected at the sampling times T 1 , T 2 , and T 3 shown in (e), correct data can be restored.
一方、図8には、変形を主体とする記録マークが連続して7つ形成された場合であって、記録されたセルが連続し、その一連の長さが再生ビーム径よりも大きくなった場合の、変形の干渉の違いと再生信号の関係を模式的に示したものである。
この場合には、図7の場合に比べて変形の干渉がより線形でなくなり、例えば図8(b)、(c)、(d)のような変形状態を示すようになる(実際はもっと複雑になる)。この干渉した変形が再生ビーム径より大きな長さであるため、変形状態の違いを明瞭に検出することができ、(b)、(c)、(d)の変形状態に合わせて、例えば、それぞれ(e)、(f)、(g)のような再生信号が得られる。
従って、(e)、(f)、(g)に示したT1〜T7のサンプリングタイムで反射レベルを検出すると、干渉の違いによって異なったデータが復元されてしまい、もはや正しいデータを復元することができない。
このように、変形が記録の主体となると、記録パターンによって記録マーク間の干渉が全く異なってしまうため(どのような再生信号が得られるか予測できない)、記録再生特性が悪化する。
On the other hand, FIG. 8 shows a case where seven recording marks mainly composed of deformation are formed in succession, in which recorded cells are continuous, and the series length is larger than the reproduction beam diameter. In this case, the relationship between the difference in deformation interference and the reproduction signal is schematically shown.
In this case, the deformation interference is less linear than in the case of FIG. 7, and for example, the deformation states as shown in FIGS. 8B, 8C, and 8D are shown (actually more complicated). Become). Since this interfering deformation is longer than the reproduction beam diameter, the difference in deformation state can be clearly detected. According to the deformation states of (b), (c), and (d), for example, Playback signals such as (e), (f), and (g) are obtained.
Therefore, when the reflection level is detected at the sampling times T 1 to T 7 shown in (e), (f), and (g), different data is restored due to the difference in interference, and correct data is no longer restored. I can't.
As described above, when the deformation becomes the main subject of recording, the interference between the recording marks is completely different depending on the recording pattern (it is impossible to predict what kind of reproduction signal is obtained), so that the recording / reproduction characteristics are deteriorated.
3. PRML方式を用いた記録再生方法について
多値記録技術とは別の高密度化技術として、現行のスライス方式の代りにPRML(パーシャル・レスポンス・アンド・マキシマム・ライクリフッド、Partial Response and Maximum Likelihood)方式の光記録媒体への利用が検討されている。
高密度化を図るために記録線密度を高めると、再生信号はより鈍った波形となる〔これは図4で説明したように、再生信号波形(d)は記録波形(b)のような矩形波にならないことを意味する〕。再生信号は等化器によって高周波成分が増幅され、等化波形へと変換されるが、高密度化されて波形が鈍ると、より高周波成分を増幅する必要がある。この高周波成分の増幅時には、等化器は信号劣化成分まで増幅を行ってしまうため、再生信号のSNRの大幅な低下を招くという問題がある。PRMLという技術は、この高密度化に伴う再生信号のSNRの低下を抑制するための再生信号処理法方式である。
3. Recording and playback method using the PRML method As a high-density technology different from the multi-value recording technology, a PRML (Partial Response and Maximum Likelihood) method is used instead of the current slice method. Application to optical recording media is being studied.
When the recording linear density is increased in order to increase the density, the reproduction signal becomes a dull waveform. (As described in FIG. 4, the reproduction signal waveform (d) is a rectangle like the recording waveform (b). It means no waves.] The reproduction signal is amplified by a high frequency component by an equalizer and converted into an equalized waveform. However, when the density is increased and the waveform becomes blunt, it is necessary to amplify the high frequency component. When this high frequency component is amplified, the equalizer amplifies even the signal degradation component, which causes a problem that the SNR of the reproduction signal is greatly reduced. The technique called PRML is a reproduction signal processing method for suppressing a decrease in SNR of a reproduction signal due to the increase in density.
以下、簡単にPRML方式について説明する。
図9の(a)〜(d)は、図4の(a)〜(d)と同様であり、それぞれ、記録すべき情報である記録データ(a)、記録波形(b)、記録マーク列(c)、再生信号波形(d)である。
図9(d)の再生波形に対して、等化器でPR(1,1)特性,PR(1,2,1)特性,PR(1,2,2,1)特性に基づく等化を行った場合の等化波形を、それぞれ図9(e)〜(g)に示す。ここで、PR(1,1)特性とは、インパルス応答が、連続する2つの識別点に各々1:1の割合で出現する特性を示し、PR(1,2,1)特性とは、インパルス応答が、連続する3つの識別点に各々1:2:1の割合で出現する特性を示し、PR(1,2,2,1)特性とは、インパルス応答が、連続する4つの識別点に各々1:2:2:1の割合で出現する特性を示す。図9(e)〜(g)に示すように、PR特性が複雑になるほど等化波形が鈍ることが分る。
PRML方式では、再生波形の特性に近いPR特性で波形等化することにより、等化器による再生信号劣化成分の増幅を抑制することが可能となる。
Hereinafter, the PRML system will be briefly described.
9 (a) to 9 (d) are the same as FIGS. 4 (a) to 4 (d), and recording data (a), recording waveform (b), and recording mark string, which are information to be recorded, respectively. (C) Reproduction signal waveform (d).
9D is equalized based on the PR (1, 1) characteristic, the PR (1, 2, 1) characteristic, and the PR (1, 2, 2, 1) characteristic by an equalizer. The equalized waveforms when performed are shown in FIGS. 9 (e) to (g), respectively. Here, the PR (1, 1) characteristic indicates a characteristic in which an impulse response appears at a ratio of 1: 1 at two consecutive identification points, and the PR (1, 2, 1) characteristic indicates an impulse. The response shows a characteristic that appears at a ratio of 1: 2: 1 at three consecutive discrimination points, and the PR (1, 2, 2, 1) characteristic means that the impulse response is at four consecutive discrimination points. Each characteristic appears at a ratio of 1: 2: 2: 1. As shown in FIGS. 9E to 9G, it can be understood that the equalization waveform becomes dull as the PR characteristic becomes more complicated.
In the PRML system, it is possible to suppress amplification of the reproduction signal deterioration component by the equalizer by performing waveform equalization with PR characteristics close to those of the reproduction waveform.
PRML方式の再生信号処理では、等化波形信号の復号にあたって、最尤復号器の代表的な一つであるビタビ復号器が用いられるのが一般的である。例えば、等化器で再生波形がPR(1,2,1)特性に等化された場合、ビタビ復号器はPR(1,2,1)特性を満足する全ての系列の中から、等化波形のサンプル系列との誤差が最も小さい系列を選択し、選択された系列に対応する二値データ(復号データ)を出力する。
このように、PRML技術を用いることで、従来と同等の光学系を用いても高密度化が実現される訳であるが、PRML技術を用いた場合であっても、記録マーク間の干渉(符号間干渉)が大きくなって、その干渉が線形でなくなると(予測できない記録マーク間干渉が起こること)、もはや信頼性の高い記録再生が不能となる。即ち、PRML方式を適用できるのは、予測可能な記録マーク間の干渉が起こることが前提で、実際の記録マーク間干渉が予測と異なるとPRML方式を用いた効果がなくなる。
従って、記録マーク間の干渉を予測可能なレベルに抑制させるためには、記録マークの変形を抑制することが必要である。
In the reproduction signal processing of the PRML method, a Viterbi decoder, which is a representative maximum likelihood decoder, is generally used for decoding an equalized waveform signal. For example, when the reproduced waveform is equalized to the PR (1, 2, 1) characteristic by the equalizer, the Viterbi decoder equalizes from all the sequences that satisfy the PR (1, 2, 1) characteristic. A sequence having the smallest error from the waveform sample sequence is selected, and binary data (decoded data) corresponding to the selected sequence is output.
As described above, by using the PRML technology, a high density can be realized even if an optical system equivalent to the conventional one is used. However, even when the PRML technology is used, interference between recording marks ( When the intersymbol interference becomes large and the interference becomes non-linear (unpredictable inter-record mark interference occurs), highly reliable recording / reproduction is no longer possible. In other words, the PRML method can be applied on the premise that interference between predictable recording marks occurs, and if the actual interference between recording marks is different from the prediction, the effect of using the PRML method is lost.
Therefore, in order to suppress the interference between the recording marks to a predictable level, it is necessary to suppress the deformation of the recording marks.
青色レーザ波長域以下の短波長で多値記録が可能な追記型光記録媒体を実現できれば、先に詳しく説明したように、従来の二値記録よりもより高い品質を有する記録マークを形成することができるため、青色レーザ波長域以下の短波長で従来の二値記録が可能な追記型光記録媒体、及びPRML方式の適用により高密化が図られた追記型光記録媒体を同時に実現できる。そこで、青色レーザ波長域以下に対応した追記型光記録媒体の実現に当っての課題は、青色レーザ波長域以下の短波長で多値記録が可能な追記型光記録媒体を実現するための課題と考えて差し支えない。
青色レーザ波長域以下の短波長で多値記録が可能な追記型光記録媒体を実現するためには、次の(1)〜(3)が課題となる。
(1)小さな記録マークが形成できる。
(2)記録マーク間の干渉が少ない。
(3)記録マークの安定性が高い。
If a write-once type optical recording medium capable of multi-value recording at a short wavelength below the blue laser wavelength range can be realized, a recording mark having higher quality than conventional binary recording can be formed as described in detail above. Therefore, it is possible to simultaneously realize a write-once type optical recording medium that can perform conventional binary recording at a short wavelength below the blue laser wavelength region, and a write-once type optical recording medium that is made dense by applying the PRML method. Therefore, a problem in realizing a write-once type optical recording medium corresponding to the blue laser wavelength range or less is a problem to realize a write-once type optical recording medium capable of multi-value recording at a short wavelength below the blue laser wavelength range. You can think of it.
In order to realize a write-once type optical recording medium capable of multi-value recording at a short wavelength below the blue laser wavelength range, the following (1) to (3) are problems.
(1) A small recording mark can be formed.
(2) There is little interference between recording marks.
(3) The stability of the recording mark is high.
ところで、従来の追記型光記録媒体では、上述の〔従来の技術〕で詳しく説明したように、変形が主体で記録が行われている場合が多い。
従来の二値記録の場合は、最短マークが再生ビーム径に対して十分な大きさを有しているため(おおよそ再生ビーム径の1/2程度)、最短マークから得られる振幅も大きい。つまり、最短マーク部の変形量が大きいことを意味する。
一方、多値記録では、最短マークが再生ビーム径に対して十分な大きさを有しないため、最短マークから得られる振幅が、二値記録の最短マークから得られる振幅の数分の1以下となる。つまり、最短マーク部の変形量が非常に小さくなること意味する。
ところで、従来のCD系やDVD系の追記型光記録媒体では、光吸収機能を有する有機色素が基板に直接接して設けられているため、基板が大きく変形する(有機色素の分解による複素屈折率変化等の寄与もあるが、基板変形が主体となって変調度が発生し易い)。基板変形は、その変形量が大きくなれば弾性変形領域を超えるため変形が固定されるが、弾性変形領域内の変形量である変形は、外部からの熱等によって変形が緩和される恐れがある。また弾性変形領域を越えた変形であっても、隣接した記録マークの形成時の熱や、隣接記録マークの変形によって、変形形状が大きく変わる恐れがある。
By the way, in the conventional write-once type optical recording medium, as described in detail in the above-mentioned [Prior Art], recording is often performed mainly with deformation.
In the case of conventional binary recording, the shortest mark has a sufficient size with respect to the reproduction beam diameter (approximately about ½ of the reproduction beam diameter), and therefore the amplitude obtained from the shortest mark is large. That is, the deformation amount of the shortest mark portion is large.
On the other hand, in multilevel recording, since the shortest mark does not have a sufficient size with respect to the reproduction beam diameter, the amplitude obtained from the shortest mark is less than a fraction of the amplitude obtained from the shortest mark in binary recording. Become. That is, it means that the deformation amount of the shortest mark portion is very small.
By the way, in the conventional CD-type and DVD-type write-once optical recording media, since the organic dye having the light absorption function is provided in direct contact with the substrate, the substrate is greatly deformed (the complex refractive index due to the decomposition of the organic dye). Although there is a contribution such as change, the degree of modulation is likely to occur mainly due to substrate deformation). If the amount of deformation of the substrate increases, the deformation exceeds the elastic deformation region, so that the deformation is fixed. However, the deformation that is the deformation amount in the elastic deformation region may be relaxed by heat from the outside. . Even if the deformation exceeds the elastic deformation region, the deformation shape may change greatly due to heat at the time of forming the adjacent recording mark or deformation of the adjacent recording mark.
この様子を図10〜図11で説明する。
図10は、従来型の構造、即ち基板/色素層/Ag反射層/保護層構成を有する追記型光記録媒体の記録マークの様子を示すものである。
Aは、再生信号の波形を示し、Bは、保護層、Ag反射層、色素層を剥がして基板表面をAFMによって観察した像を示し、Cは、Bで測定した基板のAFM像から得た基板断面の変形量を表示した図である。この図から、記録部は非常に大きな変形を起こしており、その基板変形形状は記録マーク中央部近傍が凹んだ形状を示していることが分る。また、前記図6〜8で説明したように、変形の干渉(記録マーク内の変形の干渉)が線形でないことが明らかである。
This state will be described with reference to FIGS.
FIG. 10 shows a state of a recording mark of a write-once type optical recording medium having a conventional structure, that is, a substrate / dye layer / Ag reflective layer / protective layer configuration.
A shows the waveform of the reproduction signal, B shows an image obtained by detaching the protective layer, Ag reflection layer, and dye layer and observing the substrate surface by AFM, and C is obtained from the AFM image of the substrate measured by B It is the figure which displayed the deformation amount of the board | substrate cross section. From this figure, it can be seen that the recording portion has undergone a very large deformation, and the deformation shape of the substrate shows a concave shape near the central portion of the recording mark. Further, as described with reference to FIGS. 6 to 8, it is clear that the deformation interference (deformation interference in the recording mark) is not linear.
この従来の追記型光記録媒体に、図10と同じ記録を行った後、記録パワーの約1/5程度の弱いDC光を照射した時の記録マークの様子を図11に示す。
図11では、図10と同様に、Aは、再生信号の波形を示し、Bは、保護層、Ag反射層、色素層を剥がして、基板表面をAFMによって観察した像を示し、Cは、Bで測定した基板のAFM像から得た基板断面の変形量を表示した図である。この図から、弱DC光を照射することで基板の変形状態が変化し、これによって再生信号の波形も変化することが分る。これは弱DC光の照射によって基板の変形部における歪が緩和されたためと考えられる。
また、記録マーク部の基板変形形状が、弱いDC光の照射によって変化することから、記録マーク部上にある色素層にはまだ十分な光吸収機能が残っている筈であり、従来型の追記型光記録媒体では、変形が主体となって変調度を発生させていることが分る。
FIG. 11 shows the state of a recording mark when this conventional write-once type optical recording medium is irradiated with weak DC light of about 1/5 of the recording power after performing the same recording as in FIG.
In FIG. 11, similarly to FIG. 10, A shows the waveform of the reproduction signal, B shows the image obtained by observing the substrate surface by AFM after removing the protective layer, Ag reflection layer, and dye layer, and C is It is the figure which displayed the deformation amount of the board | substrate cross section obtained from the AFM image of the board | substrate measured by B. FIG. From this figure, it can be seen that the deformation state of the substrate changes by irradiating weak DC light, and the waveform of the reproduction signal also changes accordingly. This is presumably because the distortion in the deformed portion of the substrate was alleviated by the irradiation of weak DC light.
In addition, since the deformation shape of the substrate of the recording mark portion changes due to weak DC light irradiation, the dye layer on the recording mark portion should still have a sufficient light absorption function. It can be seen that in the type optical recording medium, the modulation is generated mainly by deformation.
このように、変形が主体で記録が行われると、
(1)記録マーク内の変形の干渉が大きくなり、変形状態の違いによって、即ち記録マーク長によって再生信号波形が変化する
(2)記録マーク間の干渉が大きくなり、変形状態の違いによって、即ち記録パターンによって(前後或いは隣接トラック間の記録マークの種類によって)再生信号波形が変化する
(3)再生時、隣接トラックへの記録時、高温環境下での放置、或いは経年放置によって変形が緩和され、再生信号波形が変化する
という問題が発生するため、
(イ)ジッタ、或いはエラー率等が悪化する
(ロ)ジッタ、或いはエラー率等の記録パワーマージンが狭くなる
(ハ)最適ジッタ、或いは最小エラー率が得られる記録状態において、そのアシンメトリが不適正化し易い(アシンメトリがゼロから大きくずれる)
(ニ)小さな記録マークを安定して形成することができない
(ホ)記録マーク間の干渉を予測できない
という弊害が発生する。
これらの弊害は従来の二値記録においても当然発生する問題であるが、従来の二値記録よりも記録線密度を高めた追記型光記録媒体、即ち多値記録やPRML方式を適用した追記型光記録媒体の場合に一層顕著になる。
In this way, when recording is performed mainly with deformation,
(1) Deformation interference in the recording mark is increased, and the reproduction signal waveform changes depending on the deformation state, that is, the recording mark length. (2) Interference between recording marks is increased, and the deformation state is different. The playback signal waveform varies depending on the recording pattern (depending on the type of recording mark between the front and back or adjacent tracks). (3) Deformation is mitigated by playback, recording on adjacent tracks, leaving under high temperature environment, or leaving over time. Because the problem that the playback signal waveform changes,
(B) Jitter or error rate deteriorates (b) Recording power margin such as jitter or error rate becomes narrow (c) Asymmetry is improper in the recording state where optimum jitter or minimum error rate is obtained (Asymmetry deviates greatly from zero)
(D) A small recording mark cannot be formed stably. (E) There is a problem that interference between recording marks cannot be predicted.
These problems are naturally problems in the conventional binary recording, but the write-once type optical recording medium having a higher recording linear density than the conventional binary recording, that is, the write-once type using the multi-level recording or the PRML method. This becomes more remarkable in the case of an optical recording medium.
更に、〔背景技術〕で述べたように、従来の有機材料を記録層とした追記型光記録媒体では、次の(イ)〜(ニ)等の問題があった。
(イ)有機材料の選択の幅が非常に狭い
(ロ)波長依存性が非常に大きい
(ハ)基板の溝深さを深くしないと良好な記録再生特性を実現できない
(ニ)いわゆるランド部(溝間部)には記録ができない
そこで、本発明は、上記問題点、課題を解決するための追記型光記録媒体とその記録再生方法の提供を目的とする。
従来の追記型光記録媒体では、有機材料の分解・変質によって記録再生波長における吸収係数を低下させ、これによる大きな屈折率変化を利用して変調度を発生させていたが、本発明の追記型光記録媒体では、従来、光吸収機能による熱発生層であり、かつ分解・変質に起因した屈折率(複素屈折率の実部)変化による記録層として機能していた有機材料薄膜から、主たる熱発生層の機能を分離させ、有機材料薄膜とは別に光吸収機能を有するRO膜を設けた点に特徴がある。この追記型光記録媒体は、従来の色素を用いた追記型光記録媒体に比べて短マーク形成能力が非常に優れている。
また本発明では、更なる記録再生特性の向上という要求・期待に応えるため、保存安定性が一層優れた追記型光記録媒体の提供も目的とする。
Furthermore, as described in [Background Art], the write-once type optical recording medium using a conventional organic material as a recording layer has the following problems (a) to (d).
(B) The selection range of the organic material is very narrow (b) The wavelength dependence is very large (c) Good recording / reproduction characteristics cannot be realized unless the groove depth of the substrate is increased (d) The so-called land portion ( Therefore, it is an object of the present invention to provide a write-once type optical recording medium and a recording / reproducing method for solving the above problems and problems.
In the conventional write-once type optical recording medium, the absorption coefficient at the recording / reproducing wavelength is lowered by decomposition and alteration of the organic material, and the modulation degree is generated by utilizing a large change in the refractive index. In an optical recording medium, the main heat is generated from an organic material thin film that has conventionally functioned as a heat generation layer by a light absorption function and a recording layer by a change in refractive index (real part of complex refractive index) caused by decomposition and alteration. It is characterized in that the function of the generation layer is separated and an RO film having a light absorption function is provided separately from the organic material thin film. This write-once type optical recording medium is very excellent in the ability to form a short mark as compared with a write-once type optical recording medium using a conventional dye.
Another object of the present invention is to provide a write-once type optical recording medium with further excellent storage stability in order to meet the demand / expectation of further improvement in recording / reproducing characteristics.
上記課題は、次の1)〜31)の発明によって解決される。
1) 基板上に、少なくとも、R及びOの各元素(但し、RはY、Bi、In、Mo、V及びランタン系列元素から選ばれる一種以上の元素を表し、Oは酸素を表す)を含有する薄膜(以下、RO膜という)と、有機材料薄膜を有することを特徴とする追記型光記録媒体。
2) RO膜が、Al、Cr、Mn、Sc、In、Ru、Rh、Co、Fe、Cu、Ni、Zn、Li、Si、Ge、Zr、Ti、Hf、Sn、Pb、Mo、V及びNbの中から選ばれる一種以上の元素Mを含有することを特徴とする1)記載の追記型光記録媒体。
3) RO膜が、RxMyOの組成で表され(x、yは原子数比)、x/(x+y)≧0.3であることを特徴とする2)記載の追記型光記録媒体。
4) RO膜が、R(元素R)とRO(元素Rの酸化物)を含有することを特徴とする1)〜3)の何れかに記載の追記型光記録媒体。
5) RO膜が、R(元素R)とMO(元素Mの酸化物)を含有することを特徴とする2)又は3)記載の追記型光記録媒体。
6) RO膜が、RO(元素Rの酸化物)とMO(元素Mの酸化物)を含有することを特徴とする2)又は3)記載の追記型光記録媒体。
7) RO膜が、R(元素R)、RO(元素Rの酸化物)及びMO(元素Mの酸化物)を含有することを特徴とする2)又は3)記載の追記型光記録媒体。
8) RO膜が酸化ビスマスを含有することを特徴とする1)〜7)の何れかに記載の追記型光記録媒体。
9) RO膜がビスマスと酸化ビスマスを含有することを特徴とする1)〜4)及び7)の何れかに記載の追記型光記録媒体。
10) RO膜のRがBiであると共に4B族の中から選ばれる一種以上の元素を含有し(以下、この薄膜をBiO膜という)、該BiO膜の組成をBia4BbOd(4Bは4B族の元素、a、b、dは組成比)として、
10≦a≦40
3≦b≦20
50≦d≦70
であることを特徴とする1)記載の追記型光記録媒体。
11) BiO膜が、Al、Cr、Mn、In、Co、Fe、Cu、Ni、Zn及びTiの中から選ばれる一種以上の元素Mを含有し(以下、この薄膜をBiOM膜という)、該BiOM膜の組成をBia4BbMcOd(4Bは4B族の元素、a、b、c、dは組成比)として、
10≦a≦40
3≦b≦20
3≦c≦20
50≦d≦70
であることを特徴とする10)記載の追記型光記録媒体。
12) 4B族元素がSi又はGeであることを特徴とする10)又は11)記載の追記型光記録媒体。
13) 基板上に、少なくとも、RO膜、有機材料薄膜、反射層が順次積層されたことを特徴とする1)〜12)の何れかに記載の追記型光記録媒体。
14) 基板上に、少なくとも、有機材料薄膜、RO膜、反射層が順次積層されたことを特徴とする1)〜13)の何れかに記載の追記型光記録媒体。
15) 基板上に、少なくとも、反射層、RO膜、有機材料薄膜、カバー層が順次積層されたことを特徴とする1)〜14)の何れかに記載の追記型光記録媒体。
16) 基板上に、少なくとも、反射層、有機材料薄膜、RO膜、カバー層が順次積層されたことを特徴とする1)〜15)の何れかに記載の追記型光記録媒体。
17) 3種類以上の異なる再生信号レベルを生成する記録マークを形成でき、該再生信号レベルに基づいて記録マークの種類を判断できることを特徴とする1)〜16)の何れかに記載の追記型光記録媒体。
18) PRML方式による信号処理系で記録再生可能であることを特徴とする1)〜17)の何れかに記載の追記型光記録媒体。
19) 有機材料薄膜の主吸収帯が記録再生波長に対して長波長側に位置することを特徴とする1)〜18)の何れかに記載の追記型光記録媒体。
20) 有機材料薄膜の記録再生波長での複素屈折率虚部の値が、RO膜よりも小さいことを特徴とする19)記載の追記型光記録媒体。
21) 有機材料薄膜が、記録再生波長近傍において主吸収帯に帰属しない吸収帯を有することを特徴とする19)又は20)記載の追記型光記録媒体。
22) RO膜の光吸収機能によって、下記イ)〜ル)の少なくとも一つの記録原理により記録マークを形成できることを特徴とする1)〜21)の何れかに記載の追記型光記録媒体。
イ)RO膜を変形させる
ロ)RO膜の複素屈折率を変化させる
ハ)RO膜の組成を変化させる
ニ)RO膜を溶融させる
ホ)RO膜中の構成元素を隣接層へ拡散させる
ヘ)RO膜の結晶状態・結晶構造を変化させる
ト)RO膜中の構成元素を酸化/還元させる
チ)RO膜中の組成分布を変化させる
リ)有機材料薄膜の体積を変化させる
ヌ)有機材料薄膜の複素屈折率を変化させる
ル)有機材料薄膜に空洞部を形成させる
23) RO膜及び/又は有機材料薄膜の面積方向と膜厚方向に、3種類以上の異なる再生信号レベルを生成する記録マークを形成できることを特徴とする22)記載の追記型光記録媒体。
24) 500nm以下の光で記録再生可能であることを特徴とする1)〜23)の何れかに記載の追記型光記録媒体。
25) RO膜の記録再生波長における光吸収機能によって記録部を形成させることを特徴とする1)〜24)の何れかに記載の追記型光記録媒体の記録再生方法。
26) RO膜と有機材料薄膜の記録再生波長における光吸収機能によって記録部を形成させることを特徴とする1)〜24)の何れかに記載の追記型光記録媒体の記録再生方法。
27) 3種類以上の異なる再生信号レベルを生成する記録マークを形成させ、該再生信号レベルに基づいて記録マークの種類を判断することを特徴とする25)又は26)記載の記録再生方法。
28) PRML方式による信号処理系で記録再生を行うことを特徴とする25)〜27)の何れかに記載の記録再生方法。
29) RO膜の光吸収機能によって、下記イ)〜ル)の少なくとも一つの記録原理により記録マークを形成させることを特徴とする25)〜28)の何れかに記載の記録再生方法。
イ)RO膜を変形させる
ロ)RO膜の複素屈折率を変化させる
ハ)RO膜の組成を変化させる
ニ)RO膜を溶融させる
ホ)RO膜中の構成元素を隣接層へ拡散させる
ヘ)RO膜の結晶状態・結晶構造を変化させる
ト)RO膜中の構成元素を酸化/還元させる
チ)RO膜中の組成分布を変化させる
リ)有機材料薄膜の体積を変化させる
ヌ)有機材料薄膜の複素屈折率を変化させる
ル)有機材料薄膜に空洞部を形成させる
30) RO膜及び/又は有機材料薄膜の面積方向と膜厚方向に、3種類以上の異なる再生信号レベルを生成する記録マークを形成させることを特徴とする25)〜29)の何れかに記載の記録再生方法。
31) 500nm以下の波長で記録再生を行うことを特徴とする25)〜30)の何れかに記載の記録再生方法。
The above problems are solved by the following inventions 1) to 31).
1) Containing at least each element of R and O on the substrate (where R represents one or more elements selected from Y, Bi, In, Mo, V and lanthanum series elements, and O represents oxygen) A write-once optical recording medium comprising a thin film (hereinafter referred to as RO film) and an organic material thin film.
2) RO film is made of Al, Cr, Mn, Sc, In, Ru, Rh, Co, Fe, Cu, Ni, Zn, Li, Si, Ge, Zr, Ti, Hf, Sn, Pb, Mo, V and The write-once type optical recording medium according to 1), which contains one or more elements M selected from Nb.
3) The recordable optical recording medium according to 2), wherein the RO film is represented by a composition of RxMyO (x and y are atomic ratios) and x / (x + y) ≧ 0.3.
4) The recordable optical recording medium according to any one of 1) to 3), wherein the RO film contains R (element R) and RO (oxide of element R).
5) The write-once optical recording medium according to 2) or 3), wherein the RO film contains R (element R) and MO (oxide of element M).
6) The write-once type optical recording medium according to 2) or 3), wherein the RO film contains RO (oxide of element R) and MO (oxide of element M).
7) The write-once optical recording medium according to 2) or 3), wherein the RO film contains R (element R), RO (oxide of element R), and MO (oxide of element M).
8) The write once optical recording medium according to any one of 1) to 7), wherein the RO film contains bismuth oxide.
9) The write once optical recording medium according to any one of 1) to 4) and 7), wherein the RO film contains bismuth and bismuth oxide.
10) R of the RO film is Bi and contains one or more elements selected from the group 4B (hereinafter, this thin film is referred to as a BiO film), and the composition of the BiO film is represented by Bi a 4B b O d (4B Is a group 4B element, a, b, d are composition ratios)
10 ≦ a ≦ 40
3 ≦ b ≦ 20
50 ≦ d ≦ 70
The write-once type optical recording medium according to 1), wherein
11) The BiO film contains one or more elements M selected from Al, Cr, Mn, In, Co, Fe, Cu, Ni, Zn, and Ti (hereinafter, this thin film is referred to as a BiOM film) The composition of the BiOM film is Bi a 4B b M c O d (4B is a group 4B element, and a, b, c, and d are composition ratios),
10 ≦ a ≦ 40
3 ≦ b ≦ 20
3 ≦ c ≦ 20
50 ≦ d ≦ 70
10) The recordable optical recording medium according to 10).
12) The write-once type optical recording medium according to 10) or 11), wherein the group 4B element is Si or Ge.
13) The write-once type optical recording medium according to any one of 1) to 12), wherein at least an RO film, an organic material thin film, and a reflective layer are sequentially laminated on a substrate.
14) The write-once optical recording medium according to any one of 1) to 13), wherein at least an organic material thin film, an RO film, and a reflective layer are sequentially laminated on a substrate.
15) The recordable optical recording medium according to any one of 1) to 14), wherein at least a reflective layer, an RO film, an organic material thin film, and a cover layer are sequentially laminated on a substrate.
16) The write-once optical recording medium according to any one of 1) to 15), wherein at least a reflective layer, an organic material thin film, an RO film, and a cover layer are sequentially laminated on a substrate.
17) The write-once type according to any one of 1) to 16), wherein a recording mark for generating three or more different reproduction signal levels can be formed, and the type of the recording mark can be determined based on the reproduction signal level. Optical recording medium.
18) The write-once type optical recording medium according to any one of 1) to 17), which can be recorded and reproduced by a signal processing system using a PRML system.
19) The write-once type optical recording medium according to any one of 1) to 18), wherein the main absorption band of the organic material thin film is located on the long wavelength side with respect to the recording / reproducing wavelength.
20) The write-once type optical recording medium as described in 19), wherein the value of the imaginary part of the complex refractive index at the recording / reproducing wavelength of the organic material thin film is smaller than that of the RO film.
21) The write-once type optical recording medium according to 19) or 20), wherein the organic material thin film has an absorption band that does not belong to the main absorption band in the vicinity of the recording / reproducing wavelength.
22) The write-once type optical recording medium according to any one of 1) to 21), wherein a recording mark can be formed by at least one recording principle of the following a) to b) by the light absorption function of the RO film.
A) Deform the RO film b) Change the complex refractive index of the RO film c) Change the composition of the RO film d) Melt the RO film e) Diffuse the constituent elements in the RO film to the adjacent layers f) Change the crystal state and crystal structure of the RO film g) Oxidize / reduce the constituent elements in the RO film h) Change the composition distribution in the RO film i) Change the volume of the organic material thin film i) Change the organic material thin film A) A cavity is formed in the organic material thin film. 23) A recording mark that generates three or more different reproduction signal levels in the area direction and the film thickness direction of the RO film and / or the organic material thin film. 22) The recordable optical recording medium according to 22).
24) The write-once type optical recording medium according to any one of 1) to 23), wherein recording and reproduction are possible with light of 500 nm or less.
25) The recording / reproducing method for a write-once type optical recording medium according to any one of 1) to 24), wherein the recording part is formed by a light absorption function at a recording / reproducing wavelength of the RO film.
26) The recording / reproducing method for a write-once optical recording medium according to any one of 1) to 24), wherein the recording portion is formed by a light absorption function at a recording / reproducing wavelength of the RO film and the organic material thin film.
27) The recording / reproducing method according to 25) or 26), wherein a recording mark for generating three or more different reproduction signal levels is formed, and the type of the recording mark is determined based on the reproduction signal level.
28) The recording / reproducing method according to any one of 25) to 27), wherein recording / reproduction is performed in a signal processing system using a PRML system.
29) The recording / reproducing method according to any one of 25) to 28), wherein a recording mark is formed by at least one of the following recording principles (a) to (l) by the light absorption function of the RO film.
A) Deform the RO film b) Change the complex refractive index of the RO film c) Change the composition of the RO film d) Melt the RO film e) Diffuse the constituent elements in the RO film to the adjacent layers f) Change the crystal state and crystal structure of the RO film g) Oxidize / reduce the constituent elements in the RO film h) Change the composition distribution in the RO film i) Change the volume of the organic material thin film i) Change the organic material thin film 30) Recording marks that generate three or more different reproduction signal levels in the area direction and the film thickness direction of the RO film and / or organic material thin film The recording / reproducing method according to any one of 25) to 29), wherein:
31) The recording / reproducing method according to any one of 25) to 30), wherein recording / reproducing is performed at a wavelength of 500 nm or less.
以下、上記本発明について詳しく説明する。
本発明の課題である変形量の小さい記録マークで、大きな変調度を発生させることを実現させるためのポイントは、次の(イ)〜(ニ)である。
(イ)光吸収機能を有する層が分解、変質、組成変化、酸化/還元等を起こし、光吸収機能を有する層自体が大きく変形しないようにすること
(ロ)光吸収機能を有する層が分解、変質、組成変化、酸化/還元等を起こし、基板等の変形し易い隣接層に多くの熱を伝えないこと(光吸収機能を有する層で発生した熱を光吸収機能を有する層で消費する。これによって基板等の変形を小さくすることが可能となる。)
(ハ)変形量を低減させても十分な変調度を発生させるために、大きな光学定数変化を起こす層を有すること
(ニ)変形量を低減させても十分な変調度を発生させるために、隣接層との層界面を不明瞭化する記録原理を利用すること
このような機能を有する材料について鋭意検討した結果、本発明1のような特定の材料からなる薄膜と有機材料薄膜の組み合わせが非常に有効であることを発見した。この組み合わせを用いることで、記録マークにおける変形の寄与を従来に比べて非常に小さくすることが可能となり、〔発明が解決しようとする課題〕で説明した課題・問題点を解決することができる。
Hereinafter, the present invention will be described in detail.
The following points (a) to (d) are points for realizing generation of a large degree of modulation with a recording mark having a small deformation amount, which is an object of the present invention.
(B) A layer having a light absorption function causes decomposition, alteration, composition change, oxidation / reduction, and the like so that the layer having the light absorption function itself is not greatly deformed. (B) A layer having a light absorption function is decomposed. Do not transfer a lot of heat to adjacent layers that are easily deformed such as substrate, etc. due to alteration, composition change, oxidation / reduction, etc. (heat generated in a layer having a light absorption function is consumed in a layer having a light absorption function) (This makes it possible to reduce the deformation of the substrate and the like.)
(C) In order to generate a sufficient degree of modulation even if the amount of deformation is reduced, it has a layer that causes a large optical constant change. (D) In order to generate a sufficient degree of modulation even if the amount of deformation is reduced, Utilizing the recording principle that obscure the layer interface with the adjacent layer As a result of intensive studies on materials having such functions, the combination of a thin film made of a specific material and the organic material thin film as in the present invention 1 is extremely I found it effective. By using this combination, it is possible to make the contribution of deformation in the recording mark much smaller than in the past, and the problems and problems described in [Problems to be solved by the invention] can be solved.
ところで、従来の追記型光記録媒体では、有機材料の分解・変質によって記録再生波長における吸収係数を低下させ、これによる大きな屈折率変化を利用して変調度を発生させていた。
これに対し、本発明の追記型光記録媒体では、従来、光吸収機能による熱発生層であり且つ分解・変質に起因した屈折率(複素屈折率の実部)変化による記録層として機能していた有機材料薄膜から、主たる熱発生層の機能を分離させ、有機材料薄膜とは別に光吸収機能を有するRO膜を設けた点に特徴がある。
本発明では、次のイ)〜ル)の記録原理に基づいて記録マークが形成される。
イ)RO膜を変形させる
ロ)RO膜の複素屈折率を変化させる
ハ)RO膜の組成を変化させる
ニ)RO膜を溶融させる
ホ)RO膜中の構成元素を隣接層へ拡散させる
ヘ)RO膜の結晶状態・結晶構造を変化させる
ト)RO膜中の構成元素を酸化/還元させる
チ)RO膜中の組成分布を変化させる
リ)有機材料薄膜の体積を変化させる
ヌ)有機材料薄膜の複素屈折率を変化させる
ル)有機材料薄膜に空洞部を形成させる
By the way, in the conventional write-once type optical recording medium, the absorption coefficient at the recording / reproducing wavelength is lowered by the decomposition and alteration of the organic material, and the degree of modulation is generated by utilizing the large refractive index change.
In contrast, the write-once optical recording medium of the present invention has conventionally functioned as a heat generation layer with a light absorption function and a recording layer with a change in refractive index (real part of complex refractive index) caused by decomposition and alteration. The feature is that the function of the main heat generating layer is separated from the organic material thin film, and an RO film having a light absorption function is provided separately from the organic material thin film.
In the present invention, a recording mark is formed based on the following recording principles (a) to (l).
A) Deform the RO film b) Change the complex refractive index of the RO film c) Change the composition of the RO film d) Melt the RO film e) Diffuse the constituent elements in the RO film to the adjacent layers f) Change the crystal state and crystal structure of the RO membrane. G) Oxidize / reduce the constituent elements in the RO membrane. C) Change the composition distribution in the RO membrane. B) Change the volume of the organic material thin film. Change the complex refractive index of b) Form a cavity in the organic material thin film
特に本発明では、RO膜の各種状態変化〔即ち、上記イ)〜チ)〕を主体として記録マークを形成することが好ましい。中でも好ましいのは、ロ)〜チ)である。例えば、組成の変化や溶融、或いは構成元素の隣接層への拡散を利用することができるため、RO膜の複素屈折率を大きく変えることができ、また隣接層との層界面を不明瞭化することができ、多重反射効果を有効でなくすことができるため、小さな変形であっても大きな変調度を得ることができる。
即ち、これらの記録原理を用いることで、次の(1)〜(7)のような特性を有し、変形量の小さい記録マークで大きな変調度を発生させることができる光記録媒体とその記録再生方法を実現することができる。
(1)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、二値記録の記録再生が容易に行える高密度記録可能な追記型光記録媒体とその記録再生方法。
(2)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、多値記録の記録再生が容易に行える高密度記録可能な追記型光記録媒体とその記録再生方法。
(3)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、PRML方式による信号処理系での記録再生に適した高密度記録可能な追記型光記録媒体とその記録再生方法。
(4)記録パワーの変動に対する、ジッタやエラー率等のマージンの広い追記型光記録媒体とその記録再生方法。
(5)記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等の変化が少ない追記型光記録媒体とその記録再生方法。
(6)転写性のよい浅溝基板でも記録再生が容易に行える追記型光記録媒体とその記録再生方法。
(7)ランド部にも記録が可能な追記型光記録媒体とその記録再生方法。
In particular, in the present invention, it is preferable to form a recording mark mainly using various state changes of the RO membrane [that is, the above a) to h)]. Of these, b) to h) are preferred. For example, the composition can be changed or melted, or the diffusion of constituent elements to the adjacent layer can be used, so that the complex refractive index of the RO film can be greatly changed, and the layer interface with the adjacent layer can be obscured. Since the multiple reflection effect can be made ineffective, a large degree of modulation can be obtained even with a small deformation.
That is, by using these recording principles, an optical recording medium having the following characteristics (1) to (7) and capable of generating a large degree of modulation with a recording mark having a small deformation amount and its recording: A reproduction method can be realized.
(1) A high-density recordable write-once optical recording medium and a recording / reproducing method thereof capable of easily performing binary recording / reproduction even in a blue laser wavelength region (500 nm or less), particularly in a wavelength region near 405 nm.
(2) A high-density recordable write-once optical recording medium and a recording / reproducing method thereof capable of easily performing multi-value recording / reproduction even in a blue laser wavelength region (500 nm or less), particularly in a wavelength region near 405 nm.
(3) Write-once type optical recording medium capable of high-density recording suitable for recording / reproducing in a signal processing system using the PRML system, and recording / reproducing thereof, even in a blue laser wavelength region (500 nm or less), particularly in the wavelength region near 405 nm Method.
(4) A write-once optical recording medium having a wide margin such as jitter and error rate with respect to fluctuations in recording power and a recording / reproducing method thereof.
(5) A write-once optical recording medium in which recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, and reflectivity, etc. change little with respect to fluctuations in recording / reproducing wavelength, and a recording / reproducing method thereof.
(6) A write-once optical recording medium and a recording / reproducing method thereof that can be easily recorded / reproduced even on a shallow groove substrate having good transferability
(7) A write-once optical recording medium capable of recording on a land portion and a recording / reproducing method thereof.
1. RO膜の機能
本発明では、RO膜が主たる光吸収機能を担う。
このRO膜は、正常分散を示す材料であるため(有機材料のように、ある波長範囲内に大きな吸収帯を有する材料でないため、複素屈折率の波長依存性が小さい)、レーザの個体差や、環境温度の変化等による記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等が大きく変化するという従来の問題を大幅に解消することができる。
従来の追記型光記録媒体では、有機材料薄膜が記録層と光吸収層の機能を兼用していたため、記録再生波長に対して大きな屈折率nと比較的小さな吸収係数kを有することが有機材料の必須条件であり、そのため有機材料を分解させる温度まで到達させるには、比較的厚い膜厚が必要となっていた(また相変化型の光記録媒体に対し基板の溝深さが非常に深くなっていた)。
しかし、本発明の光記録媒体では、有機材料薄膜に主たる光吸収機能や記録機能を持たせる必要がないため、有機材料薄膜の膜厚は従来に比べて薄くすることが可能となる。
また、有機材料薄膜の薄膜化が可能となったことにより、転写性(成形性)に優れた溝深さの浅い基板を使用することが可能となり、光記録媒体の信号品質が大幅に向上すると共に従来に比べて基板を容易かつ安価に製造(成形)できる。
また、上記記録原理によるため再生時に基板の溝形状の影響を受け難く、基板形状のばらつきに対する許容度が大きくなり、従来に比べて基板の製造を容易かつ安価に行うことができる。
また、有機材料薄膜を薄くすることが可能なため、記録パワーマージン等を広げることが可能となる。
1. Function of RO Film In the present invention, the RO film has a main light absorption function.
Since this RO film is a material exhibiting normal dispersion (since it is not a material having a large absorption band in a certain wavelength range like an organic material, the wavelength dependency of the complex refractive index is small) The recording characteristics such as recording sensitivity, modulation degree, jitter, error rate, and reflectivity change greatly with respect to fluctuations in recording / reproducing wavelength due to environmental temperature changes, etc. it can.
In the conventional write-once type optical recording medium, since the organic material thin film functions as both the recording layer and the light absorption layer, the organic material has a large refractive index n and a relatively small absorption coefficient k with respect to the recording / reproducing wavelength. Therefore, in order to reach the temperature at which the organic material is decomposed, a relatively thick film thickness is required (and the groove depth of the substrate is very deep with respect to the phase change type optical recording medium). )
However, in the optical recording medium of the present invention, the organic material thin film does not need to have a main light absorption function or recording function, and therefore the organic material thin film can be made thinner than the conventional one.
In addition, since the organic material thin film can be made thinner, it is possible to use a substrate having a shallow groove depth with excellent transferability (moldability), and the signal quality of the optical recording medium is greatly improved. In addition, the substrate can be manufactured (molded) easily and at a lower cost than in the past.
Further, due to the recording principle described above, it is difficult to be affected by the groove shape of the substrate during reproduction, and the tolerance for variations in the substrate shape is increased, so that the substrate can be manufactured easily and inexpensively as compared with the conventional case.
In addition, since the organic material thin film can be thinned, the recording power margin and the like can be increased.
RO膜は、光吸収機能と共に記録機能をも有する。
具体的には、RO膜の光吸収機能によって、RO膜自身が次のような状態変化を起こす。
イ)変形(但し、従来に比べて変形量が小さい)
ロ)複素屈折率の変化〔例えば下記ハ)〜チ)に伴って複素屈折率が変化する〕
ハ)組成の変化
ニ)酸化/還元
ホ)溶融
ヘ)構成元素の隣接層への拡散
ト)組成分布変化
チ)結晶構造の変化
このように、500nm以下の記録再生波長に対して光吸収機能を有すると共に、記録機能をも持たせるために、R又はMに、500nm以下の記録再生波長に対して光吸収機能を有する元素を選択することが好ましい。
また、大きな複素屈折率変化、組成の変化、溶融を起こしたり、或いは隣接層に構成元素を拡散させるために、RO膜において、R、又はRO(Rの酸化物)は比較的低融点を有する元素を選択することが好ましい。
以上の観点から、Rとしては、Y、Bi、In、Mo、V及びランタン系列元素から選ばれる一種以上の元素を用いる。Oは酸素を表す。更に、RO膜には、Al、Cr、Mn、Sc、In、Ru、Rh、Co、Fe、Cu、Ni、Zn、Li、Si、Ge、Zr、Ti、Hf、Sn、Pb、Mo、V、及びNbの中から選ばれる一種以上の元素Mを含有させることが好ましい。
The RO film has a recording function as well as a light absorption function.
Specifically, the RO film itself undergoes the following state change by the light absorption function of the RO film.
B) Deformation (however, the amount of deformation is smaller than conventional)
B) Changes in the complex refractive index (for example, the complex refractive index changes with the following c) to h)
C) Change in composition d) Oxidation / reduction e) Melting f) Diffusion of constituent elements into adjacent layers g) Change in composition distribution h) Change in crystal structure In this way, a light absorption function for a recording / reproducing wavelength of 500 nm or less In order to provide a recording function, it is preferable to select an element having a light absorption function for R or M with respect to a recording / reproducing wavelength of 500 nm or less.
In addition, R or RO (R oxide) has a relatively low melting point in the RO film in order to cause a large complex refractive index change, composition change, melting, or to diffuse constituent elements into adjacent layers. It is preferable to select an element.
From the above viewpoint, as R, one or more elements selected from Y, Bi, In, Mo, V, and lanthanum series elements are used. O represents oxygen. Furthermore, the RO film has Al, Cr, Mn, Sc, In, Ru, Rh, Co, Fe, Cu, Ni, Zn, Li, Si, Ge, Zr, Ti, Hf, Sn, Pb, Mo, V And at least one element M selected from Nb.
RxMyO(x,yは原子数比)で表されるRO膜では、x/(x+y)≧0.3とすることによりRO膜自体の変形或いは基板等の隣接層の変形を抑制することが可能となり、記録マーク間の干渉を小さくすることができる。
また、記録再生特性の一層の向上を図るには、RとしてBiを選択することが好ましい。また、Bia4BbOd又はBia4BbMcOdで表されるBiO膜又はBiOM膜を採用することにより、記録再生特性や保存安定性性等を改善させることができる。4B族元素としてはC、Si、Ge、Sn、Pbが挙げられるが、中でもSiとGeが特に好ましい。
また、BiOM膜の場合には、添加元素Mの作用により、大きな複素屈折率変化、組成の変化、溶融を起こしたり、或いは隣接層に構成元素を拡散させる能力が更に向上する。
For RO membranes expressed as RxMyO (where x and y are atomic ratios), by setting x / (x + y) ≧ 0.3, deformation of the RO membrane itself or deformation of adjacent layers such as the substrate can be suppressed. Thus, the interference between the recording marks can be reduced.
In order to further improve the recording / reproducing characteristics, it is preferable to select Bi as R. Further, by adopting the BiO film or BiOM film represented by Bi a 4B b O d or Bi a 4B b M c O d , it is possible to improve the recording and reproduction characteristics and storage stability and the like. Examples of the group 4B element include C, Si, Ge, Sn, and Pb. Among these, Si and Ge are particularly preferable.
In the case of a BiOM film, the function of the additive element M further improves the ability to cause a large complex refractive index change, composition change, melting, or diffusion of constituent elements in the adjacent layer.
本発明のRO膜は、R元素の完全な酸化物のみからなる膜に限定されるものではなく、R元素とR元素の酸化物を同時に含有してもよい(R+ROと略記する)。
また、RO膜が元素Mを含有する場合は、(1)R−M−Oの三元化合物、(2)R+MO(元素Rと元素Mの酸化物からなる混合物)、(3)RO+MO(元素Rの酸化物と元素Mの酸化物からなる混合物)、(4)R+RO+MO(元素R、元素Rの酸化物、及び元素Mの酸化物からなる混合物)、或いは(1)〜(4)の組み合わせからなる元素、化合物を同時に含有してもよい。逆に言えば、本発明で言うRO膜とは、前記のような混合物を含めた総称である。
そして、例えば元素R(非酸化物状態)を記録によって酸化させ、これに伴ってRO膜の複素屈折率を大きく変化させることができる。この酸化という記録原理を用いれば非変形記録を実現でき、符号間干渉の小さい記録を行なうことができる。
また、例えば元素Rの酸化物を記録によって還元させ、これに伴ってRO膜の複素屈折率を大きく変化させることができる。この還元という記録原理を用いれば非変形記録を実現でき、符号間干渉の小さい記録を行なうことができる。
但し、RO膜において、元素R及び/又は元素Mが非酸化物状態で多く存在する場合は、RO膜の保存安定性を低下させる場合があるので、元素R及び/又は元素M単体の含有量は、元素R及び/又は元素Mの酸化物量に対して少ない方が好ましい場合がある。この割合は、記録感度、ジッタ、保存安定性等の兼ね合いによって適宜調整することが可能である。本発明では、光吸収機能及び記録機能の主体が元素R又はその酸化物であり、本発明で列挙した元素R群が特有な効果を有する。
特に、RO膜が、RxMyOの組成で表される場合(x、yは原子数比)、x/(x+y)≧0.3とすることで、記録再生特性の向上を図ることができる。但し、細かな記録再生特性や、保存安定性の調整にはx/(x+y)≧0.3の範囲外のRO膜を使用することも有効で、本発明はx/(x+y)≧0.3の範囲に限定されるものではない。
なお、RO膜の厚さは20〜500Åの範囲が望ましい。
The RO film of the present invention is not limited to a film made only of a complete oxide of R element, but may contain an R element and an oxide of R element at the same time (abbreviated as R + RO).
In addition, when the RO film contains the element M, (1) R-M-O ternary compound, (2) R + MO (mixture of oxides of the element R and the element M), (3) RO + MO (element A mixture of an oxide of R and an oxide of element M), (4) R + RO + MO (a mixture of an oxide of element R, an oxide of element R, and an oxide of element M), or a combination of (1) to (4) You may contain simultaneously the element and compound which consist of. In other words, the RO membrane referred to in the present invention is a general term including the mixture as described above.
For example, the element R (non-oxide state) can be oxidized by recording, and the complex refractive index of the RO film can be greatly changed accordingly. If this recording principle of oxidation is used, non-deformed recording can be realized, and recording with small intersymbol interference can be performed.
Further, for example, the oxide of the element R can be reduced by recording, and accordingly, the complex refractive index of the RO film can be greatly changed. If the recording principle of reduction is used, non-deformed recording can be realized, and recording with small intersymbol interference can be performed.
However, when the element R and / or element M is present in a non-oxide state in the RO film, the storage stability of the RO film may be lowered, so the content of the element R and / or element M alone. Is preferably smaller than the oxide amount of element R and / or element M. This ratio can be appropriately adjusted depending on the balance of recording sensitivity, jitter, storage stability, and the like. In the present invention, the main component of the light absorption function and the recording function is the element R or an oxide thereof, and the element R group listed in the present invention has a unique effect.
In particular, when the RO film is represented by a composition of RxMyO (x and y are atomic ratios), the recording / reproducing characteristics can be improved by setting x / (x + y) ≧ 0.3. However, it is also effective to use an RO membrane outside the range of x / (x + y) ≧ 0.3 in order to adjust fine recording / reproduction characteristics and storage stability. In the present invention, x / (x + y) ≧ 0. It is not limited to the range of 3.
The thickness of the RO membrane is preferably in the range of 20 to 500 mm.
2. 有機材料薄膜の機能
有機材料薄膜の機能としては、(a)断熱機能〔反射層とRO膜に有機材料薄膜が挟まれる構造の場合〕、(b)変調度の発生機能、(c)再生信号波形を補償する機能、(d)反射率やトラッキング信号等の制御機能、(e)記録感度の制御機能に大別することができる。
反射層を有する追記型光記録媒体の場合、RO膜と反射層が隣接した構造とすると、RO膜で吸収されたエネルギーが効率よく熱に変換されなくなり、適当な記録パワーで記録できなくなる場合が発生する。
この場合、RO膜と反射層の間に有機材料薄膜を導入すると、非常に薄い有機材料薄膜であっても十分な断熱効果を得ることができる。
ところで、通常、有機材料薄膜はスピンコート法によって成膜させる場合が多い。このスピンコート法で有機材料薄膜を形成する場合、ランド部に比べてグルーブ部の有機材料薄膜の膜厚が厚くなるため、グルーブ部では十分な断熱効果を確保できるが、ランド部では熱が逃げ易い構造となる。従って、グルーブ記録の場合、断熱層として有機材料薄膜を用いることにより、記録再生特性の向上を図ることが可能となる。
また、有機材料薄膜は以下の現象を引き起こすことにより、(b)変調度の発生機能を発現する。
・記録によって有機材料薄膜の体積が変化する
・記録によって有機材料薄膜の複素屈折率が変化する
・記録によって有機材料薄膜中に空洞部を形成する
・記録によるRO膜の状態変化を受容する
・反射層の変形を受容する
なお、ここで言う「RO膜の状態変化」とは、変形、複素屈折率の変化、組成の変化、溶融、構成元素の隣接層への拡散(混合)、酸化/還元、結晶構造変化等を指す。
2. Functions of the organic material thin film The functions of the organic material thin film are as follows: (a) heat insulation function (in the case of a structure in which the organic material thin film is sandwiched between the reflective layer and the RO film), (b) modulation generation function, (c) reproduction signal It can be broadly divided into a function for compensating the waveform, (d) a control function for the reflectance and tracking signal, and (e) a control function for the recording sensitivity.
In the case of a write-once type optical recording medium having a reflective layer, if the RO film and the reflective layer are adjacent to each other, the energy absorbed by the RO film cannot be efficiently converted into heat, and recording with an appropriate recording power may not be possible. Occur.
In this case, if an organic material thin film is introduced between the RO film and the reflective layer, a sufficient heat insulating effect can be obtained even with a very thin organic material thin film.
By the way, usually, an organic material thin film is often formed by spin coating. When an organic material thin film is formed by this spin coating method, since the film thickness of the organic material thin film in the groove portion is larger than that in the land portion, a sufficient heat insulating effect can be secured in the groove portion, but heat escapes in the land portion. Easy structure. Therefore, in the case of groove recording, it is possible to improve the recording / reproducing characteristics by using an organic material thin film as the heat insulating layer.
In addition, the organic material thin film exhibits the following phenomenon, and (b) exhibits a function of generating a modulation degree.
・ Recording changes the volume of the organic material thin film. ・ Recording changes the complex refractive index of the organic material thin film. ・ Recording forms a cavity in the organic material thin film. Accepting layer deformation Note that "RO membrane state change" here refers to deformation, change in complex refractive index, change in composition, melting, diffusion of constituent elements to adjacent layers (mixing), oxidation / reduction Refers to changes in crystal structure and the like.
(c)の再生信号波形を補償する機能とは、RO膜のみでは、再生信号波形が乱れる可能性が高いが〔記録極性がHigh to Low(ハイ・トゥー・ロー)の単一極性となり難い〕、有機材料薄膜を隣接層として設けることによって、再生信号波形を所望の波形(一般的には、記録極性をHigh to Low化する)にすることができる機能である。
有機材料薄膜は、その複素屈折率と膜厚を非常に広い範囲で制御することができるため、(d)の反射率やトラッキング信号等の制御機能を有することは明らかである。
また、(e)の機能については、本発明はRO膜に主たる光吸収機能を付与するが、有機材料薄膜の複素屈折率(特に複素屈折率の虚部)を制御することで、有機材料薄膜を光吸収層として補助的に用いることが可能なため、記録感度を制御することができる。
The function of compensating the reproduction signal waveform in (c) is that there is a high possibility that the reproduction signal waveform is disturbed only with the RO film [the recording polarity is unlikely to be a single polarity of High to Low (High to Low)]. By providing an organic material thin film as an adjacent layer, the reproduction signal waveform can be set to a desired waveform (generally, the recording polarity is changed to High to Low).
Since the organic material thin film can control the complex refractive index and the film thickness within a very wide range, it is clear that the organic material thin film has a control function such as the reflectance and tracking signal of (d).
As for the function (e), the present invention provides the main light absorption function to the RO film, but the organic material thin film is controlled by controlling the complex refractive index of the organic material thin film (particularly, the imaginary part of the complex refractive index). Can be used as an auxiliary light absorbing layer, so that the recording sensitivity can be controlled.
本発明では、有機材料の選択の幅を大幅に拡大するため、及び有機材料薄膜を用いた追記型光記録媒体でありながら、記録再生波長近傍での複素屈折率変化を小さくするために(波長依存性を小さくする)、有機材料薄膜は、その主吸収帯が記録再生波長に対して長波長側に位置することが好ましい(図12参照。斜線部分が記録再生波長を示す)。
有機材料薄膜を光吸収層として補助的に用いる場合、有機材料薄膜の記録再生波長での複素屈折率虚部の値は、RO膜の複素屈折率の虚部の値よりも小さいことが好ましい。何故ならば、有機材料薄膜の記録再生波長での複素屈折率虚部の値を必要以上に大きくすることは、波長依存性を悪化させることに繋がるからである。
また、有機材料薄膜を光吸収層として補助的に用いる場合、有機材料薄膜は、その主吸収帯が記録再生波長に対して長波長側に位置し、かつ、記録再生波長近傍に主吸収帯に帰属しない吸収帯を有することが好ましい。
In the present invention, in order to greatly expand the range of selection of the organic material and to reduce the complex refractive index change in the vicinity of the recording / reproducing wavelength while being a write-once type optical recording medium using an organic material thin film (wavelength It is preferable that the organic material thin film has a main absorption band located on the long wavelength side with respect to the recording / reproducing wavelength (see FIG. 12, the hatched portion indicates the recording / reproducing wavelength).
When an organic material thin film is used supplementarily as a light absorption layer, the value of the imaginary part of the complex refractive index at the recording / reproducing wavelength of the organic material thin film is preferably smaller than the value of the imaginary part of the complex refractive index of the RO film. This is because increasing the value of the imaginary part of the complex refractive index at the recording / reproducing wavelength of the organic material thin film more than necessary leads to worsening the wavelength dependency.
When an organic material thin film is used as a light absorption layer as an auxiliary layer, the organic material thin film has a main absorption band located on the long wavelength side with respect to the recording / reproducing wavelength and has a main absorption band near the recording / reproducing wavelength. It is preferable to have an absorption band that does not belong.
なお、本発明でいう「主吸収帯」とは、図13に示すように、可視域の範囲で最も吸収の大きな吸収帯を指し、一般的にはHOMO−LUMO(ホモ−ルモ)の遷移に基づく吸収帯を指す。また、本発明でいう「主吸収帯に帰属せず、主吸収帯よりも短波長側にある吸収帯」とは、図13に示すように、主吸収帯とは別の遷移に基づく吸収帯を指す(HOMO−LUMOの遷移を主体とする吸収帯ではない)。
このように、有機材料薄膜に補助的に光吸収機能を付与する場合であっても、主吸収帯に帰属しない吸収帯を記録再生波長近傍に有する有機材料薄膜を用いるため、波長依存性を小さくすることが可能となる。
以上の説明は、1つの有機材料が主吸収帯と、主吸収帯に帰属しない吸収帯を有する場合であるが、本発明では、2つ以上の有機材料を混合して図13に示すような吸収スペクトルを形成させた有機材料薄膜を用いることもでき、この場合も従来に比べて波長依存性を大幅に改善することができる。
In addition, as shown in FIG. 13, the “main absorption band” in the present invention refers to an absorption band having the largest absorption in the visible range, and generally refers to a transition of HOMO-LUMO. Refers to the absorption band based on. The “absorption band not belonging to the main absorption band and located on the shorter wavelength side than the main absorption band” as used in the present invention is an absorption band based on a transition different from the main absorption band as shown in FIG. (It is not an absorption band mainly composed of a HOMO-LUMO transition).
Thus, even when an organic material thin film is supplementarily provided with a light absorption function, the wavelength dependence is reduced because an organic material thin film having an absorption band that does not belong to the main absorption band in the vicinity of the recording / reproducing wavelength is used. It becomes possible to do.
The above description is a case where one organic material has a main absorption band and an absorption band that does not belong to the main absorption band. In the present invention, two or more organic materials are mixed and as shown in FIG. An organic material thin film in which an absorption spectrum is formed can also be used. In this case, the wavelength dependency can be greatly improved as compared with the conventional case.
本発明では変形を主体としない記録原理を用いるが、変形を排除するものではなく、記録マーク間干渉を予測できるレベルに抑制するため、変形量を低減させるのが狙いである。従って、本発明の追記型光記録媒体においても、例えば、RO膜や反射層の変形を用いることができる。例えば、この追記型光記録媒体では、有機材料薄膜が、RO膜と反射層の変形を受容する層として働くため、有機材料薄膜の膜厚を制御することで変形のし易さを制御することができる。つまり、変形記録を利用する場合、有機材料層の膜厚等によっても記録感度を調節することができる。更に、この追記型光記録媒体では、有機材料薄膜がRO膜で発生した熱が反射層から逃げることを抑制する断熱層としても働く。
以上のように、有機材料薄膜は、複素屈折率や膜厚を変えることで、記録感度を制御することができる。
In the present invention, a recording principle that does not mainly involve deformation is used, but this does not exclude deformation, and the aim is to reduce the deformation amount in order to suppress the interference between recording marks to a predictable level. Therefore, in the write-once type optical recording medium of the present invention, for example, deformation of the RO film or the reflective layer can be used. For example, in this write-once optical recording medium, since the organic material thin film functions as a layer that accepts deformation of the RO film and the reflective layer, the ease of deformation can be controlled by controlling the film thickness of the organic material thin film. Can do. That is, when using deformation recording, the recording sensitivity can be adjusted by the film thickness of the organic material layer. Furthermore, in this write-once type optical recording medium, the organic material thin film also functions as a heat insulating layer that suppresses the heat generated by the RO film from escaping from the reflective layer.
As described above, the organic material thin film can control the recording sensitivity by changing the complex refractive index and the film thickness.
本発明では、記録機能及び光吸収機能の主体をRO膜とするため、有機材料薄膜から主たる記録機能と主たる光吸収機能を排除できる。その結果、基本的に有機材料薄膜の記録再生波長における複素屈折率実部の変化を利用する必要がなくなり(勿論、記録によって複素屈折率実部が変化しても構わない)、また、有機材料薄膜は記録再生波長に対して光吸収機能を有する必要がなくなることから、有機材料の光学定数に関する従来のような厳しい制限が不要になるという顕著な効果を奏する。従って、記録再生が青色レーザ波長領域で行われる場合であっても、有機材料として、赤色レーザ波長領域に大きな吸収帯を有し青色レーザ波長領域に大きな吸収帯を持たない材料、例えばCD−RやDVD−R用の色素を用いることができる。 In the present invention, the main function of the recording function and the light absorption function is the RO film, so that the main recording function and the main light absorption function can be eliminated from the organic material thin film. As a result, it is basically unnecessary to use the change in the real part of the complex refractive index at the recording / reproducing wavelength of the organic material thin film (of course, the real part of the complex refractive index may be changed by recording). Since the thin film does not need to have a light absorption function with respect to the recording / reproducing wavelength, it has a remarkable effect that a strict restriction as in the related art relating to the optical constant of the organic material becomes unnecessary. Therefore, even when recording / reproduction is performed in the blue laser wavelength region, as an organic material, a material that has a large absorption band in the red laser wavelength region and does not have a large absorption band in the blue laser wavelength region, for example, CD-R And a dye for DVD-R can be used.
また従来は、波長制御のために、複雑な置換基や合成上困難性の高い色素を記録層として用いる必要があったが、本発明の有機材料薄膜ではそのような複雑な波長制御は不必要なため、コストの安い有機材料を選択することが可能となる。
更に、本発明における有機材料薄膜には、大きな吸収帯が記録再生波長よりも十分離れて存在する色素などの有機材料を用いることができるため(大きな吸収帯近傍では屈折率が異常分散性を示し、屈折率が波長によって大きく異なるという性質を示すが、大きな吸収帯から十分離れた波長領域では屈折率は正常分散性を示し、屈折率は波長に対し緩やかな変化を示す)、レーザの個体差や、環境温度の変化等による記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等が大きく変化するという従来の問題を大幅に解消することができる。
Conventionally, in order to control the wavelength, it has been necessary to use a complicated substituent or a dye having a high synthesis difficulty as a recording layer. However, the organic material thin film of the present invention does not require such a complicated wavelength control. Therefore, it is possible to select an organic material with a low cost.
Furthermore, since the organic material thin film in the present invention can use an organic material such as a dye having a large absorption band sufficiently away from the recording / reproducing wavelength (the refractive index shows anomalous dispersion near the large absorption band). The refractive index varies greatly depending on the wavelength, but in the wavelength region sufficiently away from the large absorption band, the refractive index shows normal dispersion, and the refractive index shows a gradual change with respect to the wavelength.) In addition, recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, and reflectivity greatly change with respect to fluctuations in recording / reproducing wavelength due to changes in environmental temperature, etc. Can do.
なお、本発明の通常の態様では、有機材料薄膜の主吸収帯と記録再生波長の関係を「記録再生波長に対して有機材料の主吸収帯が長波長側に存在する」ように設定するが、これに限定される訳ではなく、有機材料の主吸収帯と記録再生波長の関係は任意に設定することが可能である。
但し、本発明の実施に際しては、別途光吸収層(RO膜)が存在することから、反射率を高めるために、有機材料薄膜の主吸収帯と記録再生波長を遠ざけることが好ましい。この場合、記録再生波長に対して有機材料薄膜の主吸収帯が長波長側に存在しても、逆に短波長側に存在してもよい。
上記の説明から分るように、本発明は、赤色領域から青色領域まで、更には青色領域以下も含む広い範囲の記録再生波長に対して適用可能であり、用いられる記録再生波長に合わせて、後述するような公知の有機材料(特に色素)の中から上記条件を満たす材料を適宜選択することにより目的とする光記録媒体を得ることができる。
In the normal mode of the present invention, the relationship between the main absorption band of the organic material thin film and the recording / reproducing wavelength is set so that “the main absorption band of the organic material exists on the long wavelength side with respect to the recording / reproducing wavelength”. However, the present invention is not limited to this, and the relationship between the main absorption band of the organic material and the recording / reproducing wavelength can be arbitrarily set.
However, since a separate light absorption layer (RO film) is present in the practice of the present invention, it is preferable to keep the main absorption band of the organic material thin film away from the recording / reproducing wavelength in order to increase the reflectance. In this case, the main absorption band of the organic material thin film may exist on the long wavelength side with respect to the recording / reproducing wavelength, or conversely, may exist on the short wavelength side.
As can be seen from the above description, the present invention can be applied to a wide range of recording / reproducing wavelengths from the red region to the blue region, and even below the blue region, and according to the recording / reproducing wavelength used, A desired optical recording medium can be obtained by appropriately selecting a material satisfying the above conditions from known organic materials (particularly dyes) as described later.
有機材料薄膜に用いられる有機材料としては、いわゆる色素が好ましい。
本発明では、反射率を確保するために、有機材料の主吸収帯と記録再生波長を十分遠ざけることが好ましい。例えば、記録再生波長が赤色領域にある場合は、有機材料の主吸収帯に対して記録再生波長は短波長側にあっても、長波長側にあってもよい。一方、記録再生波長が青色領域以下にある場合は、有機材料の主吸収帯に対して記録再生波長を長波長側に設定することは、有機材料の分子骨格を小さくしなければいけない(共役系を短くする)ことを意味し、これは分解・爆発性の低下を招く恐れがあり、また溶解性の低下や結晶性の向上によって薄膜の形成が困難になる可能性があるため好ましくない。
従って、十分な熱分解特性を確保し、かつ良質な薄膜を形成させるために、記録再生波長が青色レーザ波長領域にある場合は、その主吸収帯が記録再生波長よりも長波長側に存在するような有機材料を選択することが好ましい。
As the organic material used for the organic material thin film, a so-called pigment is preferable.
In the present invention, it is preferable to sufficiently keep the main absorption band of the organic material and the recording / reproducing wavelength sufficiently in order to ensure the reflectance. For example, when the recording / reproducing wavelength is in the red region, the recording / reproducing wavelength may be on the short wavelength side or the long wavelength side with respect to the main absorption band of the organic material. On the other hand, when the recording / reproducing wavelength is below the blue region, setting the recording / reproducing wavelength to the longer wavelength side with respect to the main absorption band of the organic material requires a smaller molecular skeleton of the organic material (conjugated system). This is not preferable because it may lead to degradation of decomposition and explosive properties, and it may become difficult to form a thin film due to a decrease in solubility and an improvement in crystallinity.
Therefore, in order to ensure sufficient thermal decomposition characteristics and form a good quality thin film, when the recording / reproducing wavelength is in the blue laser wavelength region, the main absorption band exists on the longer wavelength side than the recording / reproducing wavelength. It is preferable to select such an organic material.
上記の要件を満足する色素としては、ポリメチン系、ナフタロシアニン系、フタロシアニン系、スクアリリウム系、クロコニウム系、ピリリウム系、ナフトキノン系、アントラキノン(インダンスレン)系、キサンテン系、トリフェニルメタン系、アズレン系、テトラヒドロコリン系、フェナンスレン系、トリフェノチアジン系各色素、及び金属錯体化合物などが挙げられる。
色素層の形成は、蒸着、スパッタリング、CVD、溶剤塗布などの通常の手段によって行なうことができる。塗布法を用いる場合には、上記染料などを有機溶剤に溶解して、スプレー、ローラーコーティング、ディッピング、スピンコーティングなどの慣用のコーティング法で行なうことができる。
用いられる有機溶剤としては、一般にメタノール、エタノール、イソプロパノールなどアルコール類;アセトン、メチルエチルケトン、シクロヘキサノンなどのケトン類;N,N−ジメチルアセトアミド、N,N−ジメチルホルムアミドなどのアミド類;ジメチルスルホキシドなどのスルホキシド類;テトラヒドロフラン、ジオキサン、ジエチルエーテル、エチレングリコールモノメチルエーテルなどのエーテル類;酢酸メチル、酢酸エチルなどのエステル類;クロロホルム、塩化メチレン、ジクロルエタン、四塩化炭素、トリクロルエタンなどの脂肪族ハロゲン化炭素類;ベンゼン、キシレン、モノクロルベンゼン、ジクロルベンゼンなどの芳香族類;メトキシエタノール、エトキシエタノールなどのセロソルブ類;ヘキサン、ペンタン、シクロヘキサン、メチルシクロヘキサンなどの炭化水素類などが挙げられる。
色素層の膜厚は、100Å〜10μm、好ましくは100〜2000Åとする。
The dyes that satisfy the above requirements include polymethine, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, and azulene. , Tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based dyes, metal complex compounds, and the like.
The dye layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, and solvent coating. In the case of using the coating method, the above-described dye or the like can be dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, or spin coating.
As the organic solvent to be used, alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfoxide such as dimethyl sulfoxide Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane; Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane, pentane, Cyclohexane, and hydrocarbons such as methylcyclohexane.
The film thickness of the dye layer is 100 to 10 μm, preferably 100 to 2000 mm.
また、本発明では、RO膜及び/又は有機材料薄膜の面積方向と膜厚方向に、3種類以上の異なる再生信号レベルを生成する記録マークを形成できる。
通常、3種類以上の異なる再生信号レベルを生成するためには、図5のように仮想された基本セルに対して、記録マ−クの面積比(光記録媒体の平面方向の面積比)を変えることが一般的である。しかし、本発明では、この面積比以外に、光記録媒体の断面方向の記録マーク形成領域の大きさを変えることで、3種類以上の異なる再生信号レベルを生成することができる。
本発明で言う、「膜厚方向に3種類以上の異なる再生信号レベルを生成する記録マークを形成する」とは、光記録媒体の断面方向の記録マーク形成領域の大きさを変えることで記録マ−クを形成し、この断面方向の記録マーク形成領域の大きさの違いに基づいて3種類以上の異なる再生信号レベルを生成することを意味する。
なお、本発明では、光記録媒体の断面方向に階調を持たせて記録することが好ましいが、勿論平面方向に階調を持たせて記録することも可能である。
In the present invention, recording marks for generating three or more different reproduction signal levels can be formed in the area direction and the film thickness direction of the RO film and / or the organic material thin film.
Usually, in order to generate three or more different reproduction signal levels, the recording mark area ratio (area ratio in the planar direction of the optical recording medium) is set to the virtual basic cell as shown in FIG. It is common to change. However, in the present invention, in addition to the area ratio, three or more different reproduction signal levels can be generated by changing the size of the recording mark formation region in the cross-sectional direction of the optical recording medium.
In the present invention, “to form a recording mark that generates three or more different reproduction signal levels in the film thickness direction” means to change the size of the recording mark forming area in the cross-sectional direction of the optical recording medium. This means that three or more different reproduction signal levels are generated based on the difference in the size of the recording mark formation region in the cross-sectional direction.
In the present invention, it is preferable to record with a gradation in the cross-sectional direction of the optical recording medium, but it is of course possible to record with a gradation in the plane direction.
本発明の追記型光記録媒体は、基板上に、少なくとも前記RO膜と有機材料薄膜を有することを特徴とするが、以下、他の構成要素について説明する。
基板の素材としては、熱的、機械的に優れた特性を有し、基板側から(基板を通して)記録再生が行われる場合には光透過特性にも優れたものであれば、特別な制限はない。
具体例としては、ポリカーボネート、ポリメタクリル酸メチル、非晶質ポリオレフィン、セルロースアセテート、ポリエチレンテレフタレートなどが挙げられるが、ポリカーボネートや非晶質ポリオレフィンが好ましい。
基板の厚さは用途により異なり、特に制限はない。
The write-once type optical recording medium of the present invention is characterized by having at least the RO film and the organic material thin film on a substrate. Other components will be described below.
As a material of the substrate, there is a special restriction as long as it has excellent thermal and mechanical properties and has excellent light transmission characteristics when recording / reproducing is performed from the substrate side (through the substrate). Absent.
Specific examples include polycarbonate, polymethyl methacrylate, amorphous polyolefin, cellulose acetate, polyethylene terephthalate and the like, and polycarbonate and amorphous polyolefin are preferred.
The thickness of the substrate varies depending on the application and is not particularly limited.
反射層の材料としては、再生光の波長で反射率の十分高いもの、例えば、Au、Al、Ag、Cu、Ti、Cr、Ni、Pt、Ta、Pdなどの金属を単独で或いは合金にして用いることができる。中でもAu、Al、Agは反射率が高く反射層の材料として適している。
また、上記金属を主成分として他の元素を含んでいても良く、他の元素としては、Mg、Se、Hf、V、Nb、Ru、W、Mn、Re、Fe、Co、Rh、Ir、Zn、Cd、Ga、In、Si、Ge、Te、Pb、Po、Sn、Biなどの金属及び半金属を挙げることができる。
中でもAgを主成分とするものは、コストが安く高反射率が出易い点から特に好ましい。
金属以外の材料で低屈折率薄膜と高屈折率薄膜を交互に積み重ねて多層膜を形成し、反射層として用いることも可能である。
反射層を形成する方法としては、例えば、スパッタ法、イオンプレーティング法、化学蒸着法、真空蒸着法等が挙げられる。
反射層の好ましい膜厚は、50〜300nmである。
As a material of the reflective layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, a metal such as Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, Pd, alone or in an alloy is used. Can be used. Among them, Au, Al, and Ag have high reflectivity and are suitable as a material for the reflective layer.
Further, the above metal may be the main component and other elements may be included. Examples of other elements include Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Mention may be made of metals and metalloids such as Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi.
Among these, those containing Ag as a main component are particularly preferable because they are inexpensive and easily provide high reflectivity.
It is also possible to form a multilayer film by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal, and use it as a reflective layer.
Examples of the method for forming the reflective layer include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition.
A preferable film thickness of the reflective layer is 50 to 300 nm.
また、基板の上や反射層の下に反射率の向上、記録特性の改善、密着性の向上等のために公知の無機系又は有機系の上引層、下引層、或いは接着層を設けることもできる。
反射層や干渉層の上に形成する保護層の材料としては、反射層や干渉層を外力から保護するものであれば特に限定されない。有機材料としては、熱可塑性樹脂、熱硬化性樹脂、電子線硬化性樹脂、UV硬化性樹脂等が挙げられる。また、無機材料としては、SiO2、SiN4、MgF2、SnO2等が挙げられる。
熱可塑性樹脂、熱硬化性樹脂は適当な溶剤に溶解した塗布液を塗布し乾燥することによって形成することができる。UV硬化性樹脂は、そのまま又は適当な溶剤に溶解した塗布液を塗布し、UV光を照射して硬化させることによって形成することができる。UV硬化性樹脂としては、例えば、ウレタンアクリレート、エポキシアクリレート、ポリエステルアクリレートなどのアクリレート系樹脂を用いることができる。
これらの材料は単独で用いても混合して用いても良いし、1層だけでなく多層膜にして用いても良い。
Also, a known inorganic or organic overcoat layer, undercoat layer, or adhesive layer is provided on the substrate or under the reflective layer in order to improve reflectivity, improve recording characteristics, improve adhesion, etc. You can also.
The material of the protective layer formed on the reflective layer and the interference layer is not particularly limited as long as it protects the reflective layer and the interference layer from external force. Examples of the organic material include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. Examples of the inorganic material include SiO 2 , SiN 4 , MgF 2 , SnO 2 and the like.
Thermoplastic resins and thermosetting resins can be formed by applying a coating solution dissolved in a suitable solvent and drying. The UV curable resin can be formed by applying a coating solution as it is or dissolved in an appropriate solvent and irradiating with UV light to cure. As the UV curable resin, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used.
These materials may be used alone or in combination, and may be used as a multilayer film as well as a single layer.
保護層の形成方法としては、記録層と同様にスピンコート法やキャスト法等の塗布法、スパッタ法、化学蒸着法等が用いられるが、中でもスピンコート法が好ましい。
保護層の膜厚は、一般に0.1〜100μmの範囲であるが、本発明においては、3〜30μmが好ましい。
また、反射層或いは干渉層面に更に基板を貼り合わせてもよく、また反射層や干渉層面相互を内面とし対向させ光学記録媒体2枚を貼り合わせても良い。
基板鏡面側に、表面保護やゴミ等の付着防止のために紫外線硬化樹脂層や、無機系薄膜等を成膜してもよい。
As a method for forming the protective layer, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used as in the recording layer. Among these, a spin coating method is preferable.
The thickness of the protective layer is generally in the range of 0.1 to 100 μm, but is preferably 3 to 30 μm in the present invention.
Further, the substrate may be further bonded to the reflective layer or the interference layer surface, or two optical recording media may be bonded to each other with the reflective layer or the interference layer surface facing each other.
An ultraviolet curable resin layer, an inorganic thin film, or the like may be formed on the mirror surface side of the substrate in order to protect the surface and prevent the adhesion of dust.
カバー層は、高密度化を図るため高NAのレンズを用いる場合に必要となる。例えば高NA化すると、再生光が透過する部分の厚さを薄くする必要がある。これは、高NA化に伴い、光学ピックアップの光軸に対してディスク面が垂直からズレる角度(いわゆるチルト角、光源の波長の逆数と対物レンズの開口数の積の2乗に比例する)により発生する収差の許容量が小さくなるためであり、このチルト角が基板の厚さによる収差の影響を受け易いためである。
従って、基板の厚さを薄くしてチルト角に対する収差の影響をなるべく小さくするようにしている。
そこで、例えば基板上に凹凸を形成して記録層とし、その上に反射層を設け、更にその上に光を透過する薄膜である光透過性のカバー層を設けるようにし、カバー層側から再生光を照射して記録層の情報を再生するような光記録媒体や、基板上に反射層を設け、その上に記録層を設け、更にこの上に光透過性を有するカバー層を設けるようにし、カバー層側から再生光を照射して記録層の情報を再生するような光記録媒体が提案されている。
このようにすれば、カバー層を薄型化していくことで対物レンズの高NA化に対応可能である。つまり、薄いカバー層を設け、このカバー層側から記録再生することで、更なる高記録密度化を図ることができる。
なお、このようなカバー層は、ポリカーボネートシートや、紫外線硬化型樹脂により形成されるのが一般的である。また、本発明で言うカバー層には、カバー層を接着するための層を含めてもよい。
本発明の追記型光記録媒体に使用されるレーザ光は、高密度記録のため波長が短いほど好ましいが、特に350〜530nmのレーザ光が好ましく、その代表例としては、中心波長405nmのレーザ光が挙げられる。
The cover layer is necessary when using a lens with a high NA in order to increase the density. For example, when the NA is increased, it is necessary to reduce the thickness of the portion through which the reproduction light is transmitted. This is due to the angle at which the disk surface deviates from the optical axis of the optical pickup as the NA increases (so-called tilt angle, proportional to the square of the product of the reciprocal of the wavelength of the light source and the numerical aperture of the objective lens). This is because the allowable amount of generated aberration is reduced, and this tilt angle is easily affected by the aberration due to the thickness of the substrate.
Therefore, the thickness of the substrate is reduced to minimize the influence of aberration on the tilt angle.
Therefore, for example, a recording layer is formed by forming irregularities on a substrate, a reflective layer is provided on the recording layer, and a light-transmitting cover layer, which is a thin film that transmits light, is provided on the recording layer. An optical recording medium that reproduces information on the recording layer by irradiating light, or a reflective layer provided on the substrate, a recording layer provided thereon, and a cover layer having optical transparency thereon. An optical recording medium that reproduces information on a recording layer by irradiating the reproducing light from the cover layer side has been proposed.
In this way, the NA of the objective lens can be increased by reducing the thickness of the cover layer. That is, it is possible to further increase the recording density by providing a thin cover layer and recording / reproducing from the cover layer side.
Such a cover layer is generally formed of a polycarbonate sheet or an ultraviolet curable resin. Further, the cover layer referred to in the present invention may include a layer for adhering the cover layer.
The laser beam used in the write-once type optical recording medium of the present invention is preferably as the wavelength is shorter for high-density recording, but a laser beam with a wavelength of 350 to 530 nm is particularly preferable. Is mentioned.
本発明によれば、次の(1)〜(7)のような追記型光記録媒体とその記録再生方法を実現できる。
(1)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、二値記録の記録再生が容易に行える高密度記録可能な追記型光記録媒体とその記録再生方法。
(2)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、多値記録の記録再生が容易に行える高密度記録可能な追記型光記録媒体とその記録再生方法。
(3)青色レーザ波長領域(500nm以下)、特に405nm近傍の波長領域であっても、PRML方式による信号処理系での記録再生に適した高密度記録可能な追記型光記録媒体とその記録再生方法。
(4)記録パワーの変動に対する、ジッタやエラー率等のマージンの広い追記型光記録媒体とその記録再生方法。
(5)記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等の変化が少ない追記型光記録媒体とその記録再生方法。
(6)転写性のよい浅溝基板を用いても記録再生が容易に行える追記型光記録媒体とその記録再生方法。
(7)ランド部にも記録が可能な追記型光記録媒体とその記録再生方法。
According to the present invention, the following write-once type optical recording medium and the recording / reproducing method thereof can be realized as in the following (1) to (7).
(1) A high-density recordable write-once optical recording medium and a recording / reproducing method thereof capable of easily performing binary recording / reproduction even in a blue laser wavelength region (500 nm or less), particularly in a wavelength region near 405 nm.
(2) A high-density recordable write-once optical recording medium and a recording / reproducing method thereof capable of easily performing multi-value recording / reproduction even in a blue laser wavelength region (500 nm or less), particularly in a wavelength region near 405 nm.
(3) Write-once type optical recording medium capable of high-density recording suitable for recording / reproducing in a signal processing system using the PRML system, and recording / reproducing thereof, even in a blue laser wavelength region (500 nm or less), particularly in the wavelength region near 405 nm Method.
(4) A write-once optical recording medium having a wide margin such as jitter and error rate with respect to fluctuations in recording power and a recording / reproducing method thereof.
(5) A write-once optical recording medium in which recording characteristics such as recording sensitivity, modulation degree, jitter, and error rate, and reflectivity, etc. change little with respect to fluctuations in recording / reproducing wavelength, and a recording / reproducing method thereof.
(6) A write-once optical recording medium and a recording / reproducing method thereof that can be easily recorded / reproduced even with a shallow groove substrate having good transferability.
(7) A write-once optical recording medium capable of recording on a land portion and a recording / reproducing method thereof.
以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらの実施例により限定されるものではない。 EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
実施例1
案内溝(溝深さ50nm)を有するポリカーボネート基板上に、スパッタ法により膜厚15nmのBi3Fe5O12薄膜を設け〔x/(x+y)=0.375>0.3〕、その上に下記〔化1〕で示される色素からなる有機材料薄膜(平均膜厚約30nm)をスピンコート法により形成し、その上にスパッタ法により膜厚150nmのAg反射層を設け、更にその上に、紫外線硬化型樹脂からなる膜厚約5μmの保護層を設けて本発明の追記型光記録媒体を作成した。
なお、〔化1〕の色素は、従来のDVD−RやDVD+Rに用いられる材料であり、青色レーザ領域には吸収が殆どない材料である。
<記録条件>
・記録線密度 : 1T=0.0917(μm)
・記録線速度 : 6.0(m/s)
・波形等化 : ノーマルイコライザー
その結果、図14に示すように、記録パワーが6.1mWで10.2%という良好なジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
変形量は最大でも10nmであることが確認できた。
Example 1
A Bi 3 Fe 5 O 12 thin film having a film thickness of 15 nm is provided on a polycarbonate substrate having a guide groove (groove depth of 50 nm) by a sputtering method [x / (x + y) = 0.375> 0.3], and further thereon. An organic material thin film (average film thickness of about 30 nm) made of a dye represented by the following [Chemical Formula 1] is formed by a spin coating method, and an Ag reflection layer having a film thickness of 150 nm is provided thereon by a sputtering method, and further, A write-once type optical recording medium of the present invention was prepared by providing a protective layer made of an ultraviolet curable resin and having a thickness of about 5 μm.
The dye of [Chemical Formula 1] is a material used for conventional DVD-R and DVD + R, and is a material that hardly absorbs in the blue laser region.
<Recording conditions>
Recording linear density: 1T = 0.0917 (μm)
・ Recording linear velocity: 6.0 (m / s)
-Waveform equalization: Normal equalizer As a result, as shown in FIG. 14, a good jitter value of 10.2% was obtained at a recording power of 6.1 mW, and a good binary recording characteristic could be realized. .
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
It was confirmed that the deformation amount was 10 nm at the maximum.
実施例2
Bi3Fe5O12の代りにBi3Fe4Cu1O12を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 2
Except for using Bi 3 Fe 4 Cu 1 O 12 instead of Bi 3 Fe 5 O 12 , the write-once type optical recording medium of the present invention was prepared in the same manner as in Example 1 and the same recording experiment was performed. . As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例3
Bi3Fe5O12の代りにBi3Fe1Al4O12を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 3
Except for using Bi 3 Fe 1 Al 4 O 12 instead of Bi 3 Fe 5 O 12 , the write-once type optical recording medium of the present invention was prepared in the same manner as in Example 1 and the same recording experiment was performed. . As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例4
Bi3Fe5O12の代りにBi3Al5O12を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 4
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 1 except that Bi 3 Al 5 O 12 was used instead of Bi 3 Fe 5 O 12 , and a similar recording experiment was performed. As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例5
Bi3Fe5O12の代りにBi38Dy8Fe41Ga13O12を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。
その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 5
Except for using Bi 38 Dy 8 Fe 41 Ga 13 O 12 instead of Bi 3 Fe 5 O 12 , the write-once type optical recording medium of the present invention was prepared in the same manner as in Example 1, and the same recording experiment was performed. went.
As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例6
Bi3Fe5O12の代りにIn3Fe5O12を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 6
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 1 except that In 3 Fe 5 O 12 was used instead of Bi 3 Fe 5 O 12 , and a similar recording experiment was performed. As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例7
〔化1〕で示される色素の代りに〔化2〕で示される色素を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。なお、〔化2〕の有機材料は、従来のDVD−RやDVD+Rに用いることのできる材料であるが、前記図13に示すような、青色レーザ領域にも吸収係数の小さなブロードな吸収帯を有する材料である(但し、主吸収帯は記録再生波長よりも長波長側に存在する)。
従って、本実施例では、Bi3Fe5O12膜膜と〔化2〕の有機材料薄膜の両方の光吸収機能で記録を行うことができ、実際、最適記録パワーを約1.0mW低下させることができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 1 except that the dye represented by [Chemical Formula 2] was used instead of the dye represented by [Chemical Formula 1], and the same recording experiment was conducted. went. As a result, as shown in Table 1, good binary recording characteristics could be realized. The organic material of [Chemical Formula 2] is a material that can be used for conventional DVD-R and DVD + R, but has a broad absorption band with a small absorption coefficient in the blue laser region as shown in FIG. (However, the main absorption band exists on the longer wavelength side than the recording / reproducing wavelength).
Therefore, in this embodiment, recording can be performed with the light absorption function of both the Bi 3 Fe 5 O 12 film and the organic material thin film of [Chemical Formula 2], and the optimum recording power is actually reduced by about 1.0 mW. I was able to.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例8
Bi3Fe5O12の代りにBi6Fe5Oz〔zを同定することが困難。x/(x+y)=0.545>0.3〕を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 8
Bi 6 Fe 5 O z [z is difficult to identify instead of Bi 3 Fe 5 O 12 Except for using x / (x + y) = 0.545> 0.3], a write-once type optical recording medium of the present invention was prepared in the same manner as in Example 1, and a similar recording experiment was performed. As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例9
Bi3Fe5O12の代りにBi15Fe5Oz〔zを同定することが困難。x/(x+y)=0.75>0.3〕を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 9
Bi 15 Fe 5 O z [z is difficult to identify instead of Bi 3 Fe 5 O 12 Except for using x / (x + y) = 0.75> 0.3], a write-once optical recording medium of the present invention was prepared in the same manner as in Example 1, and a similar recording experiment was performed. As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
実施例10
Bi3Fe5O12の代りにBi2O3〔x/(x+y)=1.0>0.3〕を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、表1に記すように、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 10
Write-once type optical recording medium of the present invention in the same manner as in Example 1, except that Bi 2 O 3 [x / (x + y) = 1.0> 0.3] was used instead of Bi 3 Fe 5 O 12 The same recording experiment was conducted. As a result, as shown in Table 1, good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
以上の結果を纏めて表1に示す。
比較例1
Bi3Fe5O12の代りにBi1Fe5Oz〔zを同定することが困難。x/(x+y)=0.167<0.3〕を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、ジッタ値は15%を越え、良好な記録を実現することができなかった。
Comparative Example 1
Bi 1 Fe 5 O z [z is difficult to identify instead of Bi 3 Fe 5 O 12 Except for using x / (x + y) = 0.167 <0.3], the write-once type optical recording medium of the present invention was prepared in the same manner as in Example 1, and the same recording experiment was performed. As a result, the jitter value exceeded 15%, and good recording could not be realized.
比較例2
Bi3Fe5O12の代りにBi2Fe5Oz〔zを同定することが困難。x/(x+y)=0.286<0.3〕を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、ジッタ値は15%を越え、良好な記録を実現することができなかった。
Comparative Example 2
Bi 2 Fe 5 O z [z is difficult to identify instead of Bi 3 Fe 5 O 12 Except for using x / (x + y) = 0.286 <0.3], a write-once optical recording medium of the present invention was prepared in the same manner as in Example 1, and the same recording experiment was performed. As a result, the jitter value exceeded 15%, and good recording could not be realized.
実施例11
Bi3Fe5O12の代りにMoO3を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、ジッタ値11%以下の記録が実現できた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.8%以下の劣化(増加)に留まった。
Example 11
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 1 except that MoO 3 was used instead of Bi 3 Fe 5 O 12 and the same recording experiment was performed. As a result, recording with a jitter value of 11% or less was realized.
In addition, a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated. As a result, both archival jitter and shelf jitter were 0.8% or less. Deterioration (increase) remained.
実施例12
Bi3Fe5O12の代りにV2O5を用いた点以外は、実施例1と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、ジッタ値11%以下の記録が実現できた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.8%以下の劣化(増加)に留まった。
Example 12
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 1 except that V 2 O 5 was used instead of Bi 3 Fe 5 O 12 , and the same recording experiment was performed. As a result, recording with a jitter value of 11% or less was realized.
In addition, a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated. As a result, both archival jitter and shelf jitter were 0.8% or less. Deterioration (increase) remained.
実施例13
案内溝(溝深さ50nm)を有するポリカーボネート基板上に、スパッタ法により膜厚12nmのBiaSibOd薄膜(BiO膜)を設け、その上に、実施例1と同じ〔化1〕で示される色素からなる有機材料薄膜(平均膜厚約30nm)をスピンコート法により形成し、その上に、スパッタ法により膜厚100nmのAg反射層を設け、更にその上に、紫外線硬化型樹脂からなる膜厚約5μmの保護層を設けて本発明の追記型光記録媒体を作成した。
上記光記録媒体に対し、パルステック工業(株)製の光ディスク評価装置DDU−1000(波長:405nm、NA:0.65)を用いて、以下の条件で、8−16変調信号の記録を行った(従来の二値記録)。
<記録条件>
・記録線密度 : 1T=0.0917(μm)
・記録線速度 : 6.0(m/s)
・波形等化 : ノーマルイコライザー
本実施例においてBiaSibOd薄膜の組成を種々変化させたところ、12%以下のジッタ値が得られたが、特に、10≦a≦40、3≦b≦20、50≦d≦70である場合に、記録パワーが約7.2mWで10%以下のジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.5%以下の劣化(増加)に留まった。
また、この記録を行った追記型光記録媒体の紫外線硬化型樹脂からなる保護層とAg反射層を剥がし、更に有機材料薄膜をエタノールで洗い流してBiaSibOd薄膜表面の変形状態をAFMにより調べた。その結果、変形量は最大でも17nmであることが確認できた。
Example 13
On a polycarbonate substrate having a guide groove (groove depth of 50 nm), a Bi a Si b O d thin film (BiO film) having a film thickness of 12 nm is provided by a sputtering method. An organic material thin film (average film thickness of about 30 nm) made of the indicated dye is formed by a spin coating method, and an Ag reflection layer having a film thickness of 100 nm is formed thereon by a sputtering method. A write-once type optical recording medium of the present invention was prepared by providing a protective layer having a thickness of about 5 μm.
Using the optical disk evaluation apparatus DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd., 8-16 modulation signal is recorded on the above optical recording medium under the following conditions. (Conventional binary recording).
<Recording conditions>
Recording linear density: 1T = 0.0917 (μm)
・ Recording linear velocity: 6.0 (m / s)
Waveform equalization: normal equalizer In this example, when the composition of the Bi a Si b O d thin film was variously changed, a jitter value of 12% or less was obtained. In particular, 10 ≦ a ≦ 40, 3 ≦ b When ≦ 20 and 50 ≦ d ≦ 70, a jitter value of 10% or less was obtained at a recording power of about 7.2 mW, and good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, the deterioration of jitter was investigated. Deterioration (increase) remained.
Also, remove the protective layer and the Ag reflective layer made of an ultraviolet curable resin of a write-once optical recording medium was subjected to recording, AFM a deformation state of the Bi a Si b O d thin film surface rinse further organic material thin film in ethanol We investigated by. As a result, it was confirmed that the deformation amount was 17 nm at the maximum.
実施例14
BiaSibOdの代りにBiaGebOdを用いた点以外は、実施例13と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、実施例13と同様に、a、b、dが上記数値範囲内にある場合に、記録パワーが約7.2mWで10%以下のジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.8%以下の劣化(増加)に留まった。
Example 14
A write-once optical recording medium of the present invention was produced in the same manner as in Example 13 except that Bi a Ge b O d was used instead of Bi a Si b O d and a similar recording experiment was performed. As a result, as in Example 13, when a, b, and d are within the above numerical range, a jitter value of 10% or less is obtained at a recording power of about 7.2 mW, and good binary recording characteristics are obtained. Could be realized.
In addition, a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated. As a result, both archival jitter and shelf jitter were 0.8% or less. Deterioration (increase) remained.
実施例15
BiaSibOdの代りにBiaSibFecOdを用いた点以外は、実施例13と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、BiaSibFecOd薄膜(BiOM膜)の組成が、10≦a≦40、3≦b≦20、3≦c≦20、50≦d≦70の場合に、記録パワーが約7.5mWで10%以下のジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.5%以下の劣化(増加)に留まった。
Example 15
Bi a Si b O d except using Bi a Si b Fe c O d instead of, create a write-once optical recording medium of the present invention in the same manner as in Example 13 was subjected to the same recording experiments . As a result, when the composition of the BiaSibFecOd thin film (BiOM film) is 10 ≦ a ≦ 40, 3 ≦ b ≦ 20, 3 ≦ c ≦ 20, 50 ≦ d ≦ 70, the recording power is about 7.5 mW and 10%. The following jitter values were obtained, and good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, the deterioration of jitter was investigated. Deterioration (increase) remained.
実施例16
BiaSibFecOdの代りにBi3SiM4O12(Mは、Al、Cr、Mn、In、Co、Cu、Ni、Zn、Tiの何れか)を用いた点以外は、実施例15と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、どの元素の場合も記録パワーが約7.0mWで10%以下のジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.5%以下の劣化(増加)に留まった。
Example 16
Implemented except that Bi 3 SiM 4 O 12 (M is any one of Al, Cr, Mn, In, Co, Cu, Ni, Zn, and Ti) is used instead of Bi a Si b Fe c O d A write-once type optical recording medium of the present invention was prepared in the same manner as in Example 15, and the same recording experiment was conducted. As a result, for any element, a jitter value of 10% or less was obtained at a recording power of about 7.0 mW, and good binary recording characteristics could be realized.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, the deterioration of jitter was investigated. Deterioration (increase) remained.
実施例17
案内溝(溝深さ50nm)を有するポリカーボネート基板上に、実施例1と同じ〔化1〕で示される色素からなる有機材料薄膜(平均膜厚約30nm)をスピンコート法により形成し、その上に、スパッタ法により膜厚25nmのBiaSibOd薄膜(BiO膜)を設け、その上に、スパッタ法により膜厚25nmのAg反射層を設け、更にその上に、紫外線硬化型樹脂からなる膜厚約5μmの保護層を設けて本発明の追記型光記録媒体を作成した。
実施例13と同様にBiaSibOd薄膜の組成を種々変化させたところ、12%以下のジッタ値が得られたが、特に、10≦a≦40、3≦b≦20、50≦d≦70である場合に、記録パワーが約7.4mWで10%以下のジッタ値が得られ、良好な二値記録特性を実現することができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.8%以下の劣化に留まった。
Example 17
On a polycarbonate substrate having guide grooves (groove depth of 50 nm), an organic material thin film (average film thickness of about 30 nm) made of the same dye as shown in Example 1 is formed by spin coating, In addition, a 25 nm-thick Bi a Si b Od thin film (BiO film) is provided by sputtering, and a 25 nm-thick Ag reflective layer is provided thereon by sputtering, and further, an ultraviolet curable resin is formed thereon. A write-once type optical recording medium of the present invention was prepared by providing a protective layer having a thickness of about 5 μm.
When the composition of the Bi a Si b O d thin film was variously changed in the same manner as in Example 13, a jitter value of 12% or less was obtained. In particular, 10 ≦ a ≦ 40, 3 ≦ b ≦ 20, 50 ≦ When d ≦ 70, a jitter value of 10% or less was obtained at a recording power of about 7.4 mW, and good binary recording characteristics could be realized.
In addition, a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated. As a result, both archival jitter and shelf jitter were 0.8% or less. Deterioration remained.
実施例18
〔化1〕で示される色素の代りに実施例7と同じ〔化2〕で示される色素を用いた点以外は、実施例13と同様にして本発明の追記型光記録媒体を作成し、同様の記録実験を行った。その結果、良好な二値記録特性を実現することができた。なお、〔化2〕の有機材料は、前述したように、青色レーザ領域にも吸収係数の小さなブロードな吸収帯を有する材料である(図13参照。但し、主吸収帯は記録再生波長よりも長波長側に存在する)。
従って、本実施例では、BiaSibOd膜膜と〔化2〕の有機材料薄膜の両方の光吸収機能で記録を行うことができ、実際、最適記録パワーを約1.0mW低下させることができた。
また、上記数値範囲を満足する媒体について、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも1.0%以下の劣化(増加)に留まった。
Example 18
A write-once optical recording medium of the present invention was prepared in the same manner as in Example 13 except that the same dye as shown in [Chemical formula 2] was used instead of the dye shown in [Chemical formula 1]. A similar recording experiment was conducted. As a result, good binary recording characteristics could be realized. As described above, the organic material of [Chemical Formula 2] is a material having a broad absorption band with a small absorption coefficient in the blue laser region (see FIG. 13; however, the main absorption band is longer than the recording / reproducing wavelength). It exists on the long wavelength side).
Therefore, in this embodiment, recording can be performed with the light absorption function of both the BiaSibOd film and the organic material thin film of [Chemical Formula 2], and the optimum recording power can actually be reduced by about 1.0 mW.
In addition, when a medium satisfying the above numerical range was subjected to a storage test for 100 hours in an environment of 80 ° C. and a relative humidity of 85%, and the deterioration of jitter was investigated, both archival jitter and shelf jitter were 1.0% or less. Deterioration (increase) remained.
比較例3
案内溝(溝深さ50nm)を有するポリカーボネート基板上に、FOM−559(和光純薬社製フタロシアニン)からなる有機材料薄膜(平均膜厚約80nm)をスピンコート法によって形成し、その上に、スパッタ法により膜厚150nmのAg反射層を設け、更にその上に、紫外線硬化型樹脂からなる膜厚約5μmの保護層を設けて追記型光記録媒体を作成した(従来の層構成を青色領域でも適用した例)。
なお、FOM−559(和光純薬社製フタロシアニン)は、従来型の追記型光記録媒体に用いられる有機材料と同様に、記録再生波長である405nm近傍で比較的小さな複素屈折率虚部(吸収係数)と、比較的大きな複素屈折率実部を有する材料である。
上記光記録媒体に対し、パルステック工業(株)製の光ディスク評価装置DDU−1000(波長:405nm、NA:0.65)を用いて、以下の条件で、8−16変調信号の記録を行った。
<記録条件>
・記録線密度 : 1T=0.0917(μm)
・記録線速度 : 6.0(m/s)
・波形等化 : ノーマルイコライザー
その結果、記録パワー約11.0mWで10.1%というジッタ値が得られた。
また、80℃、相対湿度85%の環境下で100時間の保存試験を行いジッタの劣化を調査したところ、アーカイバルジッタ、シェルフジッタとも0.6%以下の劣化(増加)に留まった。
しかし、この記録を行った追記型光記録媒体の紫外線硬化型樹脂からなる保護層とAg反射層を剥がし、更に有機材料薄膜をエタノールで洗い流して基板表面の変形状態をAFMにより調べたところ、変形量は最大では100nmを超えており、基板溝深さ以上の変形を起こしていることが確認できた。
また、図15に示すように、隣接トラックに記録した記録マークの変形によって(図15のM)、その記録マークよりも時間的に先に記録された記録マークの変形状態(図15のN)が干渉を受け、その形状が大きく変わっていることが確認できた。
従って、更なる高密度化には不利であることが明らかになった。
Comparative Example 3
On a polycarbonate substrate having a guide groove (groove depth of 50 nm), an organic material thin film (average film thickness of about 80 nm) made of FOM-559 (phthalocyanine manufactured by Wako Pure Chemical Industries, Ltd.) is formed by a spin coating method. A write-once optical recording medium was prepared by providing an Ag reflective layer having a thickness of 150 nm by sputtering, and further providing a protective layer having a thickness of about 5 μm made of an ultraviolet curable resin thereon (the conventional layer configuration was changed to a blue region). But example applied).
Note that FOM-559 (phthalocyanine manufactured by Wako Pure Chemical Industries, Ltd.) has a relatively small complex refractive index imaginary part (absorption) in the vicinity of 405 nm, which is the recording / reproducing wavelength, like the organic material used in the conventional write-once optical recording medium. Coefficient) and a relatively large complex refractive index real part.
Using the optical disk evaluation apparatus DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd., 8-16 modulation signal is recorded on the above optical recording medium under the following conditions. It was.
<Recording conditions>
Recording linear density: 1T = 0.0917 (μm)
・ Recording linear velocity: 6.0 (m / s)
-Waveform equalization: Normal equalizer As a result, a jitter value of 10.1% was obtained at a recording power of about 11.0 mW.
Further, when the deterioration of jitter was investigated by conducting a storage test for 100 hours in an environment of 80 ° C. and 85% relative humidity, both the archival jitter and the shelf jitter remained at 0.6% or less (increase).
However, the protective layer made of the ultraviolet curable resin and the Ag reflection layer of the write-once optical recording medium on which this recording was performed were peeled off, and the organic material thin film was washed away with ethanol, and the deformation state of the substrate surface was examined by AFM. The amount exceeded 100 nm at the maximum, and it was confirmed that deformation exceeding the substrate groove depth occurred.
Further, as shown in FIG. 15, the deformation state of the recording mark recorded earlier in time (N in FIG. 15) by the deformation of the recording mark recorded in the adjacent track (M in FIG. 15). It was confirmed that the shape was greatly changed due to interference.
Therefore, it became clear that it was disadvantageous for further densification.
実施例19
実施例1で作成した追記型光記録媒体に対し、パルステック工業(株)製の光ディスク評価装置DDU−1000(波長:405nm、NA:0.65)を用いて、以下の条件で、8値の多値記録を行った。
<記録条件>
・記録線密度 : 基本セル長=0.47(μm)
・記録線速度 : 3.5(m/s)
・記録パターン: 孤立マークと連続マーク(2つの空の基本セルを挟
んで、多値レベルが同一な記録マークが4つ連続した連続マークと
1つの孤立マークを、7つの異なる多値レベルについて記録した)
その結果、図16に示すように、変調度(ダイナミックレンジ)が大きく(変調度60%)、連続記録部においても多値記録レベルの変動が非常に小さな記録を実現できることが分った。
また、上記の実験では、溝部(グルーブ部)に多値記録を行ったが、溝間部(ランド)にも同様に記録が行えた。
Example 19
For the write-once optical recording medium created in Example 1, eight values were used under the following conditions using an optical disk evaluation apparatus DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd. Multi-valued recording was performed.
<Recording conditions>
Recording linear density: Basic cell length = 0.47 (μm)
Recording linear velocity: 3.5 (m / s)
Recording pattern: isolated mark and continuous mark (with two empty basic cells
Then, four consecutive recording marks with the same multi-value level
One isolated mark was recorded for 7 different multilevel levels)
As a result, as shown in FIG. 16, it has been found that the modulation degree (dynamic range) is large (modulation degree 60%), and even in the continuous recording portion, it is possible to realize recording in which the fluctuation of the multilevel recording level is very small.
In the above experiment, multi-value recording was performed on the groove (groove), but recording was also possible on the groove (land).
実施例20
実施例13で作成した追記型光記録媒体に対し、実施例19と同様にして8値の多値記録を行った。
その結果、実施例19の場合と同様に、変調度(ダイナミックレンジ)が大きく(変調度60%)、連続記録部においても多値記録レベルの変動が非常に小さな記録を実現できることが分った。
また、上記の実験では、溝部(グルーブ部)に多値記録を行ったが、溝間部(ランド)にも同様に記録が行えた。
Example 20
Eight-valued multi-value recording was performed on the write-once type optical recording medium created in Example 13 in the same manner as in Example 19.
As a result, as in Example 19, it was found that recording with a large modulation level (dynamic range) (modulation level 60%) and a very small fluctuation of the multilevel recording level could be realized even in the continuous recording unit. .
In the above experiment, multi-value recording was performed on the groove (groove), but recording was also possible on the groove (land).
比較例4
比較例3の追記型光記録媒体に対し、パルステック工業(株)製の光ディスク評価装置DDU−1000(波長:405nm、NA:0.65)を用いて、以下の条件で、8値の多値記録を行った。
<記録条件>
・記録線密度 : 基本セル長=0.47(μm)
・記録線速度 : 3.5(m/s)
・記録パターン: 孤立マークと連続マーク(実施例19と同様)
その結果、図17に示すように、連続記録部において、いわゆる「変調度のひげ」が発生し、多値記録レベルの変動が非常に大きくなり(連続記録部において、再生レベルが同一でなくてはならない)、多値記録に適さないことが確認できた。また、記録パワーを低下させると変調度のひげが発生しなくなることが確認できたが、この時は、変調度(ダイナミックレンジ)が非常に小さくなり(変調度は20%)、またSNRが低下した。
また、この記録を行った追記型光記録媒体の紫外線硬化型樹脂からなる保護層とAg反射層を剥がし、更に有機材料薄膜をエタノールで洗い流して基板表面の変形状態をAFMにより調べた。
その結果、図18に示すように、基本セルにおける記録マークの大きさが大きい連続記録部で〔(d)〜(f)〕、線形でない記録マーク間の干渉が発生しており、「変調度のひげ」が、変形の干渉による変形形状の大幅な劣化に基づくものであることが確認できた。
また、図19に示すように、基板の変形量と変調度のひげ量(連続記録マーク部の先頭と後端との再生レベルの差)の関係を調べた結果、変形量が約50nmを超えると連続記録部のレベル均一性が乱れ、多値記録に適さなくなることが分った。
即ち、変形量を低減させないと多値記録に対応した追記型光記録媒体を実現できないことが明らかとなった(しかし、この比較例4の追記型光記録媒体では、変形量を大きくしないと十分な変調度が発生しない)。
更に、上記の実験では、溝部(グルーブ部)に多値記録を行ったが、溝間部(ランド)には全く記録が行えなかった。
Comparative Example 4
For the write-once optical recording medium of Comparative Example 3, an optical disc evaluation apparatus DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd. Value recording was performed.
<Recording conditions>
Recording linear density: Basic cell length = 0.47 (μm)
Recording linear velocity: 3.5 (m / s)
Recording pattern: isolated mark and continuous mark (same as Example 19)
As a result, as shown in FIG. 17, a so-called “modulation whisker” occurs in the continuous recording portion, and the fluctuation of the multi-level recording level becomes very large (the playback level is not the same in the continuous recording portion). It was confirmed that it was not suitable for multi-value recording. Further, it was confirmed that when the recording power was reduced, the modulation factor was not whisked, but at this time, the modulation factor (dynamic range) was very small (modulation factor was 20%) and the SNR was reduced. did.
Further, the protective layer made of the ultraviolet curable resin and the Ag reflection layer of the write-once type optical recording medium on which this recording was performed were peeled off, and the organic material thin film was washed away with ethanol, and the deformation state of the substrate surface was examined by AFM.
As a result, as shown in FIG. 18, in the continuous recording portion where the size of the recording mark in the basic cell is large [(d) to (f)], interference between non-linear recording marks occurs. It has been confirmed that “the whiskers” are based on the substantial deterioration of the deformed shape due to the deformation interference.
Further, as shown in FIG. 19, as a result of examining the relationship between the deformation amount of the substrate and the whisker amount of the modulation degree (difference in reproduction level between the head and the rear end of the continuous recording mark portion), the deformation amount exceeds about 50 nm. As a result, it was found that the level uniformity of the continuous recording portion was disturbed, making it unsuitable for multi-value recording.
That is, it became clear that the write-once type optical recording medium corresponding to multilevel recording cannot be realized unless the deformation amount is reduced (however, the write-once type optical recording medium of Comparative Example 4 is sufficient unless the deformation amount is increased). The degree of modulation does not occur).
Furthermore, in the above experiment, multi-value recording was performed in the groove portion (groove portion), but no recording was possible in the groove portion (land).
実施例21
基本セル長を更に小さく0.26(μm)とした点以外は、実施例19と同様にして、8値の多値記録を行った。
その結果、図20に示すように、変調度(ダイナミックレンジ)が大きく(変調度は60%)、連続記録部においても多値記録レベルの変動が非常に小さな記録を実現できることが分った。
また、この記録を行った追記型光記録媒体の紫外線硬化型樹脂からなる保護層とAg反射層を剥がし、更に有機材料薄膜をエタノールで洗い流してBiFeO表面の変形状態をSEM(走査型電子顕微鏡)により調べた。
その結果、図21に示すように、殆ど変形を伴わないで記録マークが形成されていることが確認できた(SEM写真では明らかな変形が認められない)。
また、記録部表面と断面のTEM像観察から、本発明の多値記録可能な追記型光記録媒体では、BiFeO薄膜及び/又は有機材料薄膜の面積方向への多値記録と共に、膜厚方向にも多値記録されていた。
Example 21
Eight-valued multi-value recording was performed in the same manner as in Example 19 except that the basic cell length was further reduced to 0.26 (μm).
As a result, as shown in FIG. 20, it has been found that the modulation degree (dynamic range) is large (modulation degree is 60%), and even in the continuous recording portion, it is possible to realize recording in which the fluctuation of the multilevel recording level is very small.
In addition, the protective layer made of the ultraviolet curable resin and the Ag reflection layer of the write-once optical recording medium on which this recording was performed were peeled off, and the organic material thin film was washed away with ethanol to show the deformation state of the BiFeO surface by SEM (scanning electron microscope). We investigated by.
As a result, as shown in FIG. 21, it was confirmed that the recording mark was formed with almost no deformation (no obvious deformation was observed in the SEM photograph).
In addition, from the observation of the TEM image of the surface and cross section of the recording portion, the write-once type optical recording medium capable of multi-value recording of the present invention has multi-value recording in the area direction of the BiFeO thin film and / or organic material thin film in the film thickness direction. Was also multi-valued.
実施例22
基本セル長を更に小さく0.26(μm)とした点以外は、実施例20と同様にして、8値の多値記録を行った。
その結果、実施例21の場合と同様に、変調度(ダイナミックレンジ)が大きく(変調度は60%)、連続記録部においても多値記録レベルの変動が非常に小さな記録を実現できることが分った。
また、この記録を行った追記型光記録媒体の紫外線硬化型樹脂からなる保護層とAg反射層を剥がし、更に有機材料薄膜をエタノールで洗い流してBiaSibOd表面の変形状態をSEM(走査型電子顕微鏡)により調べたところ、実施例21の場合と同様に、殆ど変形を伴わないで記録マークが形成されていることが確認できた。
また、記録部表面と断面のTEM像観察から、本発明の多値記録可能な追記型光記録媒体では、BiaSibOd及び/又は有機材料薄膜の面積方向への多値記録と共に、膜厚方向にも多値記録されていた。
Example 22
Eight-valued multi-value recording was performed in the same manner as in Example 20 except that the basic cell length was further reduced to 0.26 (μm).
As a result, as in the case of Example 21, the modulation degree (dynamic range) is large (modulation degree is 60%), and it is understood that the continuous recording portion can realize recording with very little fluctuation of the multilevel recording level. It was.
Further, a deformation state of the recording made of an ultraviolet curable resin of a write-once optical recording medium was subjected to remove the protective layer and the Ag reflective layer, further wash the organic material thin film in ethanol Bi a Si b O d surface SEM ( As a result of examination using a scanning electron microscope, it was confirmed that the recording marks were formed with almost no deformation as in the case of Example 21.
Further, from the observation of the TEM image of the surface and cross section of the recording part, in the write-once type optical recording medium capable of multi-value recording of the present invention, in addition to multi-value recording in the area direction of BiaSibOd and / or organic material thin film, Multi-valued was recorded.
実施例23
実施例1で作成した追記型光記録媒体に対し、最短マーク長が0.205μmとなる記録線密度でPR(1,2,1)方式を用いて記録再生を行った。
その結果、通常の二値記録におけるジッタ評価ではジッタ値が20%を超えたが、PRML方式で復号した結果、BER(ビットエラーレート)は10−5台となり非常に良好な記録再生が行えることが確認できた。
Example 23
Recording and reproduction were performed on the write-once type optical recording medium prepared in Example 1 using the PR (1, 2, 1) system at a recording linear density at which the shortest mark length was 0.205 μm.
As a result, the jitter value exceeds 20% in the jitter evaluation in the normal binary recording, but as a result of decoding by the PRML method, the BER (bit error rate) becomes 10 −5 units, and very good recording / reproduction can be performed. Was confirmed.
実施例24
実施例13で作成した追記型光記録媒体に対し、最短マーク長が0.205μmとなる記録線密度でPR(1,2,1)方式を用いて記録再生を行った。
その結果、通常の二値記録におけるジッタ評価ではジッタ値が20%を超えたが、PRML方式で復号した結果、BER(ビットエラーレート)は10−5台となり非常に良好な記録再生が行えることが確認できた。
Example 24
Recording / reproduction was performed on the write-once type optical recording medium created in Example 13 using the PR (1, 2, 1) system at a recording linear density with a shortest mark length of 0.205 μm.
As a result, the jitter value exceeds 20% in the jitter evaluation in the normal binary recording, but as a result of decoding by the PRML method, the BER (bit error rate) becomes 10 −5 units, and very good recording / reproduction can be performed. Was confirmed.
比較例5
比較例3で作成した追記型光記録媒体に対し、最短マーク長が0.205μmとなる記録線密度でPR(1,2,1)方式を用いて記録再生を行った。
その結果、通常の二値記録におけるジッタ評価ではジッタ値が20%を超え、PRML方式で復号した結果、BER(ビットエラーレート)も10−3台となり、この記録線密度では、PRML方式を適用しても記録再生が行えないことが確認できた。
Comparative Example 5
Recording / reproduction was performed on the write-once type optical recording medium created in Comparative Example 3 using the PR (1, 2, 1) method at a recording linear density at which the shortest mark length was 0.205 μm.
As a result, in jitter evaluation in normal binary recording, the jitter value exceeds 20%, and as a result of decoding by the PRML method, the BER (bit error rate) is 10 −3 units, and the PRML method is applied at this recording linear density. However, it was confirmed that recording and playback could not be performed.
実施例25
実施例1で作成した追記型光記録媒体の吸収率Qを測定した。具体的には、該光記録媒体の反射率Rと透過率Tを測定し、1−R−Tなる値を吸収率Qとした(図22中のX)。
また比較のため、実施例1の追記型光記録媒体と同様にして、青色レーザ波長域でも記録再生が可能な材料であるフタロシアニン化合物を使用している市販のCD−Rの吸収率Q(図22中のZ)と、比較例3で作成した追記型光記録媒体の吸収率Q(図22中のY)も測定した(フタロシアニン化合物を用いた市販のCD−Rそのままでは、基板のトラックピッチや基板厚の関係で、青色レーザ対応の評価装置では記録再生できないが、市販のCD−Rを破壊してフタロシアニン化合物を溶剤で洗い流し、青色レーザに対応した基板に再度塗布し直すと、青色レーザ対応の評価装置で記録再生が可能である)。
その結果、本発明の追記型光記録媒体は、500nm以下の波長域、特に400nmの近傍で吸収率Qの変動が非常に小さいことが確認できた。
従って、本発明の追記型光記録媒体は、記録再生波長の変動に対し、記録感度、変調度、ジッタ、エラー率といったような記録特性や、反射率等の変化が少ない追記型光記録媒体を実現できることが確認できた。
Example 25
The absorptance Q of the write-once type optical recording medium prepared in Example 1 was measured. Specifically, the reflectance R and transmittance T of the optical recording medium were measured, and the value 1-RT was defined as the absorption factor Q (X in FIG. 22).
For comparison, similarly to the write-once type optical recording medium of Example 1, the absorptivity Q of a commercially available CD-R using a phthalocyanine compound that is a material that can be recorded and reproduced even in the blue laser wavelength region (see FIG. 22) and the absorptivity Q (Y in FIG. 22) of the write-once type optical recording medium prepared in Comparative Example 3 were also measured (the track pitch of the substrate with the commercially available CD-R using the phthalocyanine compound as it was. Due to the relationship between the thickness of the substrate and the thickness of the substrate, recording / reproduction cannot be performed with an evaluation device compatible with blue lasers. However, if a commercially available CD-R is destroyed, the phthalocyanine compound is washed away with a solvent, It can be recorded and played back with a corresponding evaluation device).
As a result, it was confirmed that the write-once type optical recording medium of the present invention has a very small variation in the absorptance Q in the wavelength region of 500 nm or less, particularly in the vicinity of 400 nm.
Therefore, the write-once optical recording medium of the present invention is a write-once optical recording medium with little change in recording characteristics such as recording sensitivity, modulation degree, jitter, error rate, and reflectance, etc., with respect to fluctuations in the recording / reproducing wavelength. It was confirmed that it could be realized.
実施例26
実施例1で作成した追記型光記録媒体に形成された記録マークがどのような原理に基づいて形成されているかを確認する実験を行った。
即ち、実施例1で作成した追記型光記録媒体の記録部分をFIB(集束イオンビーム加工装置)によって切断し、この部分をTEM(透過型電子顕微鏡)で観察した。
その結果、図23に示すように、記録マーク部ではBiFeO薄膜の構成元素が隣接層(基板及び有機材料薄膜)へ拡散していること、BiFeO薄膜の組成が変化している可能性があることが確認できた。また、電子線回折による分析では、記録部では結晶化が起こっており、結晶粒が形成されていることが確認された。
更に、有機材料薄膜にも空洞部の形成が見られる場合があり、複素屈折率が変化していることが確認できた。
以上の結果から、本発明の記録原理が変形を主体とするものでないことが確認できた。
Example 26
An experiment was conducted to confirm on what principle the recording marks formed on the write-once type optical recording medium prepared in Example 1 were formed.
That is, the recording portion of the write-once type optical recording medium prepared in Example 1 was cut by FIB (focused ion beam processing apparatus), and this portion was observed with a TEM (transmission electron microscope).
As a result, as shown in FIG. 23, the constituent elements of the BiFeO thin film are diffused into the adjacent layers (substrate and organic material thin film) in the recording mark portion, and the composition of the BiFeO thin film may be changed. Was confirmed. Further, in the analysis by electron beam diffraction, crystallization occurred in the recording portion, and it was confirmed that crystal grains were formed.
Furthermore, the formation of a cavity portion may be observed in the organic material thin film, and it was confirmed that the complex refractive index was changed.
From the above results, it was confirmed that the recording principle of the present invention is not mainly composed of deformation.
実施例27
実施例13で作成した追記型光記録媒体に形成された記録マークがどのような原理に基づいて形成されているかを確認する実験を行った。
即ち、実施例13で作成した追記型光記録媒体の記録部分をFIB(集束イオンビーム加工装置)によって切断し、この部分をTEM(透過型電子顕微鏡)で観察した。
その結果、実施例26の場合と同様に、記録マーク部ではBiaSibOd薄膜の構成元素が隣接層(基板及び有機材料薄膜)へ拡散していること、BiaSibOd薄膜の組成が変化している可能性があることが確認できた。また、電子線回折による分析では、記録部では結晶化が起こっており、結晶粒が形成されていることが確認された。
更に、有機材料薄膜にも空洞部の形成が見られる場合があり、複素屈折率が変化していることが確認できた。
以上の結果から、本発明の記録原理が変形を主体とするものでないことが確認できた。
Example 27
An experiment was conducted to confirm on what principle the recording marks formed on the write-once type optical recording medium created in Example 13 were formed.
That is, the recording portion of the write-once type optical recording medium prepared in Example 13 was cut by FIB (focused ion beam processing apparatus), and this portion was observed with a TEM (transmission electron microscope).
As a result, as in the case of Example 26, the recording mark portion that Bi a Si b O d thin film of the constituent elements are diffused into the adjacent layers (the substrate and the organic material film), Bi a Si b O d thin It was confirmed that there was a possibility that the composition of was changed. Further, in the analysis by electron beam diffraction, crystallization occurred in the recording portion, and it was confirmed that crystal grains were formed.
Furthermore, the formation of a cavity portion may be observed in the organic material thin film, and it was confirmed that the complex refractive index was changed.
From the above results, it was confirmed that the recording principle of the present invention is not mainly composed of deformation.
n 複素屈折率の実部
k 複素屈折率の虚部
δn 記録再生波長における複素屈折率の実部の変化
δk 記録再生波長における複素屈折率の虚部の変化
δλ 記録再生波長の変動幅
T1〜T7 サンプリングタイム
A 再生信号の波形
B 保護層、Ag反射層、色素層を剥がして基板表面をAFM観察した像
C Bで測定した基板のAFM像から基板断面の変形量を表示した図
M 隣接トラックに記録した記録マーク
N Mよりも時間的に先に記録された記録マーク
a 多値レベル2(図5参照)の連続記録部
b 多値レベル3(図5参照)の連続記録部
c 多値レベル4(図5参照)の連続記録部
d 多値レベル5(図5参照)の連続記録部
e 多値レベル6(図5参照)の連続記録部
f 多値レベル7(図5参照)の連続記録部
X 実施例1の追記型光記録媒体の吸収率
Y 比較例1の追記型光記録媒体の吸収率
Z 市販のCD−Rの吸収率
n real part of complex refractive index k imaginary part of complex refractive index δn change of real part of complex refractive index at recording / reproducing wavelength δk change of imaginary part of complex refractive index at recording / reproducing wavelength δλ fluctuation range of recording / reproducing wavelength T 1 to T 7 Sampling time A Reproduced signal waveform B Image obtained by removing the protective layer, Ag reflection layer, and dye layer and observing the substrate surface with AFM CB Amount of deformation of the substrate cross section measured from the AFM image of the substrate M Recording mark recorded on the track NM Recording mark recorded earlier than M a Continuous recording section of multi-level 2 (see FIG. 5) b Continuous recording section of multi-level 3 (see FIG. 5) c Multi Continuous recording section at value level 4 (see FIG. 5) d Continuous recording section at multi-level level 5 (see FIG. 5) e Continuous recording section at multi-level level 6 (see FIG. 5) f Multi-level level 7 (see FIG. 5) Continuous recording part X Write-once type light of Example 1 Absorption rate of absorptivity Z commercial CD-R of write-once optical recording medium absorptivity Y Comparative Example 1 of the recording medium
Claims (31)
10≦a≦40
3≦b≦20
50≦d≦70
であることを特徴とする請求項1記載の追記型光記録媒体。 R in RO membrane contains one or more elements selected from Group 4B with a Bi (hereinafter, this film is referred BiO film), the Bi a 4B b O d (4B The composition of the BiO film 4B Group elements, a, b and d are composition ratios)
10 ≦ a ≦ 40
3 ≦ b ≦ 20
50 ≦ d ≦ 70
The write-once type optical recording medium according to claim 1, wherein
10≦a≦40
3≦b≦20
3≦c≦20
50≦d≦70
であることを特徴とする請求項10記載の追記型光記録媒体。 The BiO film contains one or more elements M selected from Al, Cr, Mn, In, Co, Fe, Cu, Ni, Zn, and Ti (hereinafter, this thin film is referred to as a BiOM film), and the BiOM film As a composition of Bi a 4B b M c O d (4B is a group 4B element, a, b, c, and d are composition ratios),
10 ≦ a ≦ 40
3 ≦ b ≦ 20
3 ≦ c ≦ 20
50 ≦ d ≦ 70
The write-once type optical recording medium according to claim 10, wherein
イ)RO膜を変形させる
ロ)RO膜の複素屈折率を変化させる
ハ)RO膜の組成を変化させる
ニ)RO膜を溶融させる
ホ)RO膜中の構成元素を隣接層へ拡散させる
ヘ)RO膜の結晶状態・結晶構造を変化させる
ト)RO膜中の構成元素を酸化/還元させる
チ)RO膜中の組成分布を変化させる
リ)有機材料薄膜の体積を変化させる
ヌ)有機材料薄膜の複素屈折率を変化させる
ル)有機材料薄膜に空洞部を形成させる The write-once type optical recording medium according to any one of claims 1 to 21, wherein a recording mark can be formed according to at least one of the following recording principles (a) to (l) by the light absorption function of the RO film.
A) Deform the RO film b) Change the complex refractive index of the RO film c) Change the composition of the RO film d) Melt the RO film e) Diffuse the constituent elements in the RO film to the adjacent layers f) Change the crystal state and crystal structure of the RO membrane. G) Oxidize / reduce the constituent elements in the RO membrane. C) Change the composition distribution in the RO membrane. B) Change the volume of the organic material thin film. Change the complex refractive index of b) Form a cavity in the organic material thin film
イ)RO膜を変形させる
ロ)RO膜の複素屈折率を変化させる
ハ)RO膜の組成を変化させる
ニ)RO膜を溶融させる
ホ)RO膜中の構成元素を隣接層へ拡散させる
ヘ)RO膜の結晶状態・結晶構造を変化させる
ト)RO膜中の構成元素を酸化/還元させる
チ)RO膜中の組成分布を変化させる
リ)有機材料薄膜の体積を変化させる
ヌ)有機材料薄膜の複素屈折率を変化させる
ル)有機材料薄膜に空洞部を形成させる 29. The recording / reproducing method according to claim 25, wherein a recording mark is formed by at least one of the following recording principles (a) to (l) by the light absorption function of the RO film.
A) Deform the RO film b) Change the complex refractive index of the RO film c) Change the composition of the RO film d) Melt the RO film e) Diffuse the constituent elements in the RO film to the adjacent layers f) Change the crystal state and crystal structure of the RO membrane. G) Oxidize / reduce the constituent elements in the RO membrane. C) Change the composition distribution in the RO membrane. B) Change the volume of the organic material thin film. Change the complex refractive index of b) Form a cavity in the organic material thin film
31. A recording / reproducing method according to claim 25, wherein recording / reproducing is performed at a wavelength of 500 nm or less.
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JP2004064452A JP4577872B2 (en) | 2003-04-15 | 2004-03-08 | Write-once optical recording medium |
EP04008899A EP1475793B1 (en) | 2003-04-15 | 2004-04-14 | Write-once-read-many optical recording medium and process for recording and reproducing of the optical medium |
US10/824,227 US6933032B2 (en) | 2003-04-15 | 2004-04-14 | Write-once-read-many optical recording media and process for recording and reproducing information on the media |
DE602004010451T DE602004010451T2 (en) | 2003-04-15 | 2004-04-14 | Write-once, multi-read optical disc and method for writing and reading the disc |
US11/159,920 US7413788B2 (en) | 2003-04-15 | 2005-06-23 | Write-once-read-many optical recording media and process for recording and reproducing information on the media |
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