JPH05334725A - Optical information recording medium - Google Patents
Optical information recording mediumInfo
- Publication number
- JPH05334725A JPH05334725A JP4140815A JP14081592A JPH05334725A JP H05334725 A JPH05334725 A JP H05334725A JP 4140815 A JP4140815 A JP 4140815A JP 14081592 A JP14081592 A JP 14081592A JP H05334725 A JPH05334725 A JP H05334725A
- Authority
- JP
- Japan
- Prior art keywords
- recording
- wavelength
- layer
- protective layer
- recording medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 23
- 239000010410 layer Substances 0.000 claims abstract description 34
- 239000011241 protective layer Substances 0.000 claims abstract description 27
- 230000008033 biological extinction Effects 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 239000000758 substrate Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000673 Indium arsenide Inorganic materials 0.000 description 1
- 229910019018 Mg 2 Si Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
Landscapes
- Optical Record Carriers And Manufacture Thereof (AREA)
Abstract
(57)【要約】
【目的】 波長の異なるレーザ光に対して情報の記録・
消去を可能とする。
【構成】 レーザ光の照射による昇温・冷却の熱履歴の
違いにより光学的性質の変化する記録層を有する光学情
報記録媒体において、波長λ1 に対する消衰係数ｋ
1 と、波長λ2 に対する消衰係数ｋ2 との間に、ｋ1 ＜
ｋ2 の関係を有する保護層を記録層に隣接して設ける。
(57) [Abstract] [Purpose] Recording of information for laser beams of different wavelengths
Enables erasure. [Structure] In an optical information recording medium having a recording layer whose optical properties change due to the difference in thermal history of temperature rise / cooling by irradiation of laser light, an extinction coefficient k with respect to wavelength λ 1
1, between the extinction coefficient k 2 with respect to the wavelength lambda 2, k 1 <
A protective layer having a relationship of k 2 is provided adjacent to the recording layer.
Description
【０００１】[0001]
【産業上の利用分野】本発明は、熱履歴の違いにより誘
起される相変化にともなう光学定数の変化を利用して情
報の記録及び消去を行う光学情報記録媒体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium for recording and erasing information by utilizing the change of optical constants accompanying the phase change induced by the difference of thermal history.
【０００２】[0002]
【従来の技術】レーザ光の照射によって情報の記録・消
去・再生を行う光学情報記録媒体としては、光磁気ディ
スクや相変化型光ディスクなどが知られている。このう
ち、相変化型光ディスクでは、基板１上に下部保護層
２、記録層３、上部保護層４、反射層５がこの順に設け
られた図１に示すような４層構成が通常用いられる。情
報の記録消去は、レーザ光の照射による昇温・冷却の熱
履歴の違いによって誘起される記録層の非晶質・結晶間
などの相変化を利用して行われる。すなわち、記録層を
溶融し、急冷することにより非晶質化させ、記録を行
い、また、結晶化温度以上に一定時間保持することによ
り結晶化させ、消去を行う。下部保護層２、記録層３、
上部保護層４及び反射層５の膜厚は、感度、Ｃ／Ｎ、消
去率、書換え可能繰り返し回数などの観点から最適化さ
れる。2. Description of the Related Art Magneto-optical disks and phase-change optical disks are known as optical information recording media for recording / erasing / reproducing information by irradiating laser light. Among them, in a phase change type optical disc, a four-layer structure as shown in FIG. 1 in which a lower protective layer 2, a recording layer 3, an upper protective layer 4, and a reflective layer 5 are provided in this order on a substrate 1 is usually used. Recording and erasing of information is performed by utilizing a phase change such as between an amorphous state and a crystalline state of the recording layer, which is induced by a difference in thermal history of temperature rising and cooling due to laser light irradiation. That is, the recording layer is melted and rapidly cooled to be made amorphous, and recording is performed. Further, the recording layer is kept at a temperature equal to or higher than the crystallization temperature for a certain time to be crystallized and erased. Lower protective layer 2, recording layer 3,
The film thicknesses of the upper protective layer 4 and the reflective layer 5 are optimized from the viewpoints of sensitivity, C / N, erasing rate, number of rewritable repetitions, and the like.
【０００３】[0003]
【発明が解決しようとする課題】波長８３０ｎｍの半導
体レーザを用いた書換え可能な光ディスクが現在市販さ
れているが、光ディスクにはさらなる高速化・高密度化
が要求されている。波長の短いレーザ光を用いること
は、高密度化の有力な手段の１つであるが、レーザ光の
短波長化に対して相変化光ディスクが有している大きな
問題点の１つは、結晶化温度以上に保持される時間が短
くなることである。つまり、情報の消去が確実に行えな
くなることである。したがって、情報の消去を確実に行
うには、レーザ光の短波長化にともない、上部保護層の
膜厚を十分に厚くしなければならない。その結果、従来
に比べ成膜時間が増加することになる。Rewritable optical discs using semiconductor lasers having a wavelength of 830 nm are currently on the market, but optical discs are required to have higher speed and higher density. Using a laser beam having a short wavelength is one of the effective means for increasing the density, but one of the major problems that a phase change optical disc has with respect to the shortening of the wavelength of a laser beam is a crystal. That is, the time for which the temperature is kept above the oxidation temperature is shortened. That is, information cannot be erased reliably. Therefore, in order to surely erase the information, the film thickness of the upper protective layer must be made sufficiently thick as the wavelength of the laser beam becomes shorter. As a result, the film formation time will be longer than in the conventional case.
【０００４】さらに、短波長レーザに対して上部保護層
や反射層の膜厚を最適化した媒体では、長波長レーザに
対しては溶融後の冷却速度が小さくなり、記録層を非晶
質化させること、すなわち、情報の記録を行うことが困
難となる。その結果、現在市販されているドライブでは
記録を行うことができず、互換性を保つことができなく
なる。Further, in the medium in which the film thickness of the upper protective layer and the reflective layer is optimized for the short wavelength laser, the cooling rate after melting is small for the long wavelength laser, and the recording layer is made amorphous. It is difficult to do so, that is, to record information. As a result, recording cannot be performed with the drives currently on the market, and compatibility cannot be maintained.
【０００５】本発明の目的は、波長の異なるレーザ光に
対して情報の記録・消去が可能な光学情報記録媒体を提
供することにある。It is an object of the present invention to provide an optical information recording medium capable of recording / erasing information with respect to laser beams having different wavelengths.
【０００６】[0006]
【課題を解決するための手段】本発明は、レーザ光の照
射による昇温・冷却の熱履歴の違いにより光学的性質の
変化する記録層と、記録層に接する保護層および反射層
とからなる光学情報記録媒体において、波長の異なる
（波長λ1 ，波長λ2 ）２種類のレーザ光に対して記録
・消去が可能なことを特徴としている。SUMMARY OF THE INVENTION The present invention comprises a recording layer whose optical properties change due to the difference in heat history of temperature rise / cooling by irradiation of laser light, and a protective layer and a reflective layer which are in contact with the recording layer. The optical information recording medium is characterized by being capable of recording / erasing with respect to two types of laser light having different wavelengths (wavelength λ 1 and wavelength λ 2 ).
【０００７】また、本発明によれば、前記保護層は、波
長λ1 に対する消衰係数ｋ1 と波長λ2 に対する消衰係
数ｋ2 との間にｋ1 ＜ｋ2 の関係を有する保護層である
のが好ましい。Further, according to the present invention, the protective layer, a protective layer having a relationship of k 1 <k 2 between the extinction coefficient k 2 for the extinction coefficient k 1 and wavelength lambda 2 for the wavelength lambda 1 Is preferred.
【０００８】[0008]
【作用】８３０ｎｍの光に対してはほとんど透明であ
り、５００ｎｍ付近の光に対して吸収のある物質である
Ｓｉ、Ｍｇ2 Ｓｉ、Ｍｇ2 Ｇｅ、ＩｎＡｓ等の物質を保
護層として用いると、波長５００ｎｍの光に対しては、
上部保護層で光を吸収し、温度が上昇するので、記録層
から反射層への熱の逃げが緩やかになり、記録層が結晶
化温度以上に保持される時間を長くすることができる。When a substance such as Si, Mg 2 Si, Mg 2 Ge, InAs, which is a substance that is almost transparent to light of 830 nm and absorbs light near 500 nm, is used as the protective layer, For 500 nm light,
Since the upper protective layer absorbs light and the temperature rises, the heat escape from the recording layer to the reflective layer becomes slower, and the time for which the recording layer is kept at the crystallization temperature or higher can be lengthened.
【０００９】また、波長８３０ｎｍの光に対しては、上
部保護層で光の吸収がほとんどないので、記録層から反
射層への熱の逃げは大きく、十分な冷却速度を確保する
ことができる。Further, with respect to the light having the wavelength of 830 nm, since the upper protective layer hardly absorbs the light, the heat is largely released from the recording layer to the reflective layer, and a sufficient cooling rate can be secured.
【００１０】[0010]
【実施例】次に、本発明の実施例について図面を参照し
て説明する。Embodiments of the present invention will now be described with reference to the drawings.
【００１１】図１は、本発明に係る光学情報記録媒体の
一実施例の断面図である。本実施例は、基板１上に下部
保護層２、記録層３、上部保護層４、反射層５を順次積
層した構成となっており、基板１としてポリカーボネイ
ト（ＰＣ）を用い、下部保護層２としてＳｉＮを１００
ｎｍ、記録層３としてＧｅ2 Ｓｂ2 Ｔｅ5 を２５ｎｍ、
上部保護層４としてＭｇ2 Ｓｅを１２０ｎｍ、反射層５
としてＡｌを５０ｎｍを順次スパッタリングにより積層
して作成されている。Ｍｇ2 Ｓｅは６００ｎｍ付近に吸
収端を有し、８３０ｎｍの光に対しては透明である。FIG. 1 is a sectional view of an embodiment of an optical information recording medium according to the present invention. In this embodiment, a lower protective layer 2, a recording layer 3, an upper protective layer 4 and a reflective layer 5 are sequentially laminated on a substrate 1. Polycarbonate (PC) is used as the substrate 1 and the lower protective layer 2 is used. As SiN 100
nm, Ge 2 Sb 2 Te 5 as the recording layer 3 is 25 nm,
120 nm of Mg 2 Se is used as the upper protective layer 4, and the reflective layer 5
Is formed by sequentially stacking 50 nm of Al by sputtering. Mg 2 Se has an absorption edge near 600 nm and is transparent to light of 830 nm.
【００１２】以上のような構成とすることにより、波長
５００ｎｍ付近の光に対しては、上部保護層４で光を吸
収し、温度が上昇するので、記録層３から反射層５への
熱の逃げが緩やかになり、記録層３が結晶化温度以上に
保持される時間を長くすることができ、また、波長８３
０ｎｍの光に対しては、上部保護層４で光の吸収がほと
んどないので、記録層３から反射層５への熱の逃げは大
きく、十分な冷却速度を確保することができる。With the above-mentioned structure, the upper protective layer 4 absorbs the light having a wavelength of about 500 nm and the temperature rises. Therefore, heat from the recording layer 3 to the reflective layer 5 is absorbed. The escape becomes gentle, the time during which the recording layer 3 is kept at the crystallization temperature or higher can be lengthened, and the wavelength 83
As for 0 nm light, the upper protective layer 4 hardly absorbs the light, so that the heat escape from the recording layer 3 to the reflective layer 5 is large and a sufficient cooling rate can be secured.
【００１３】上記ディスクを線速１１．３ｍ／ｓで回転
させ、波長８３０ｎｍの半導体レーザ及び固体レーザの
２次高調波光を利用した波長５３２ｎｍのレーザ光を用
いて記録消去を行った。The disk was rotated at a linear velocity of 11.3 m / s, and recording / erasing was performed using laser light of wavelength 532 nm utilizing the second harmonic light of a semiconductor laser of wavelength 830 nm and solid-state laser.
【００１４】周波数２．１２ＭＨｚ、ｄｕｔｙ＝５０％
及び周波数８．４７ＭＨｚ、ｄｕｔｙ＝５０％の信号を
用いてオーバライトを行った結果を図２及び図３に示
す。８３０ｎｍのレーザ光に対しては、記録パワ１０ｍ
Ｗ、消去パワ５〜６ｍＷの時に、両周波数に対してＣ／
Ｎ４５ｄＢ以上、消去率２８ｄＢ以上の特性を示した。
また、５３２ｎｍのレーザ光に対しては、記録パワ７ｍ
Ｗ、消去パワ３〜４ｍＷの時に、両周波数に対してＣ／
Ｎ４８ｄＢ以上、消去率２５ｄＢ以上の特性を示した。Frequency 2.12 MHz, duty = 50%
2 and 3 show the results of overwriting using a signal having a frequency of 8.47 MHz and a duty of 50%. Recording power of 10 m for laser light of 830 nm
W, C / C for both frequencies when the erase power is 5-6 mW
The characteristics are N45 dB or more and an erasing rate of 28 dB or more.
In addition, the recording power is 7 m for a laser beam of 532 nm.
W / Elimination power 3-4 mW C / C for both frequencies
The characteristics are N48 dB or more and an erasing rate of 25 dB or more.
【００１５】このように、本実施例は、波長λ1 に対す
る消衰係数ｋ1 と、波長λ2 に対する消衰係数ｋ2 との
間に、ｋ1 ＜ｋ2 の関係を有する保護層を用いることに
より、異なる波長に対して記録消去を行うことが可能に
なる。[0015] Thus, the present embodiment uses the extinction coefficient k 1 for the wavelength lambda 1, between the extinction coefficient k 2 with respect to the wavelength lambda 2, the protective layer having a relationship of k 1 <k 2 As a result, it becomes possible to perform recording / erasing for different wavelengths.
【００１６】[0016]
【発明の効果】以上説明したように本発明は、波長λ1
に対する消衰係数ｋ1 と、波長λ2 に対する消衰係数ｋ
2 との間に、ｋ1 ＜ｋ2 の関係を有する保護層を用いる
ことにより、λ1 およびλ2 両波長に対して記録・消去
が可能になるという効果を有する。As described above, according to the present invention, the wavelength λ 1
Extinction coefficient k 1 for λ 2 and extinction coefficient k for wavelength λ 2
Between the 2, by using a protective layer having a relationship of k 1 <k 2, it has the effect that the recording and erasing with respect to lambda 1 and lambda 2 both wavelengths is possible.
【００１７】また、上部保護層を厚くする必要がないの
で成膜時間の増加を防ぐことができるという効果を有す
る。Further, since it is not necessary to thicken the upper protective layer, it is possible to prevent an increase in film forming time.
【図１】本発明の光学情報記録媒体の断面図である。FIG. 1 is a sectional view of an optical information recording medium of the present invention.
【図２】本発明の相変化光ディスクの８３０ｎｍレーザ
光に対する記録消去特性を示す図である。FIG. 2 is a diagram showing recording / erasing characteristics of a phase change optical disc of the present invention with respect to 830 nm laser light.
【図３】本発明の相変化光ディスクの５３２ｎｍレーザ
光に対する記録消去特性を示す図である。FIG. 3 is a diagram showing recording / erasing characteristics of a phase change optical disc of the present invention with respect to a 532 nm laser beam.
１ 基板 ２ 下部保護層 ３ 記録層 ４ 上部保護層 ５ 反射層 1 substrate 2 lower protective layer 3 recording layer 4 upper protective layer 5 reflective layer
Claims (2)
の違いにより光学的性質の変化する記録層と、記録層に
接する保護層および反射層とからなる光学情報記録媒体
において、波長の異なる（波長λ1 ，波長λ2 ）２種類
のレーザ光に対して記録・消去が可能なことを特徴とす
る光学情報記録媒体。1. An optical information recording medium comprising a recording layer whose optical properties change due to a difference in thermal history of temperature rise / cooling by irradiation of laser light, and a protective layer and a reflective layer in contact with the recording layer An optical information recording medium characterized by being capable of recording / erasing with respect to two different types of laser light (wavelength λ 1 , wavelength λ 2 ).
て、前記保護層は、波長λ1 に対する消衰係数ｋ1 と波
長λ2 に対する消衰係数ｋ2 との間にｋ1 ＜ｋ2 の関係
を有する保護層であることを特徴とする光学情報記録媒
体。2. A optical information recording medium according to claim 1, wherein the protective layer is provided between the extinction coefficient k 2 for the extinction coefficient k 1 and wavelength lambda 2 for the wavelength lambda 1 k 1 of <k 2 An optical information recording medium, which is a protective layer having a relationship.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4140815A JP2795057B2 (en) | 1992-06-02 | 1992-06-02 | Optical information recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4140815A JP2795057B2 (en) | 1992-06-02 | 1992-06-02 | Optical information recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05334725A true JPH05334725A (en) | 1993-12-17 |
| JP2795057B2 JP2795057B2 (en) | 1998-09-10 |
Family
ID=15277381
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4140815A Expired - Lifetime JP2795057B2 (en) | 1992-06-02 | 1992-06-02 | Optical information recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2795057B2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03286432A (en) * | 1990-03-31 | 1991-12-17 | Taiyo Yuden Co Ltd | Optical information recording medium |
| JPH0562248A (en) * | 1991-09-04 | 1993-03-12 | Nippon Telegr & Teleph Corp <Ntt> | Dual-wavelength optical disk medium |
| JPH05242524A (en) * | 1992-02-28 | 1993-09-21 | Victor Co Of Japan Ltd | Optical recording medium |
-
1992
- 1992-06-02 JP JP4140815A patent/JP2795057B2/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03286432A (en) * | 1990-03-31 | 1991-12-17 | Taiyo Yuden Co Ltd | Optical information recording medium |
| JPH0562248A (en) * | 1991-09-04 | 1993-03-12 | Nippon Telegr & Teleph Corp <Ntt> | Dual-wavelength optical disk medium |
| JPH05242524A (en) * | 1992-02-28 | 1993-09-21 | Victor Co Of Japan Ltd | Optical recording medium |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2795057B2 (en) | 1998-09-10 |
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