JP2910767B2 - Optical disc and information recording method - Google Patents

Optical disc and information recording method

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Publication number
JP2910767B2
JP2910767B2 JP59251889A JP25188984A JP2910767B2 JP 2910767 B2 JP2910767 B2 JP 2910767B2 JP 59251889 A JP59251889 A JP 59251889A JP 25188984 A JP25188984 A JP 25188984A JP 2910767 B2 JP2910767 B2 JP 2910767B2
Authority
JP
Japan
Prior art keywords
phase
temperature
recording
reflectance
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.)
Expired - Fee Related
Application number
JP59251889A
Other languages
Japanese (ja)
Other versions
JPS61131235A (en
Inventor
哲郎 峯村
佳均 前田
寿 安藤
鉄男 伊藤
正一 永井
隆二 渡辺
誠喜 清水
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP59251889A priority Critical patent/JP2910767B2/en
Priority to US06/801,950 priority patent/US4651172A/en
Priority to CA000496335A priority patent/CA1238489A/en
Priority to EP85308665A priority patent/EP0186329B1/en
Priority to DE8585308665T priority patent/DE3583599D1/en
Priority to KR1019850008929A priority patent/KR920001263B1/en
Publication of JPS61131235A publication Critical patent/JPS61131235A/en
Application granted granted Critical
Publication of JP2910767B2 publication Critical patent/JP2910767B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24304—Metals or metalloids group 2 or 12 elements (e.g. Be, Ca, Mg, Zn, Cd)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24308—Metals or metalloids transition metal elements of group 11 (Cu, Ag, Au)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
    • G11B2007/24302—Metals or metalloids
    • G11B2007/24312—Metals or metalloids group 14 elements (e.g. Si, Ge, Sn)
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0045—Recording
    • G11B7/00454—Recording involving phase-change effects

Description

【発明の詳細な説明】 〔発明の利用分野〕 本発明は、高エネルギーを投入された状態での分光反
射率が、低エネルギーを投入された状態での分光反射率
よりも高い記録媒体、および該記録媒体への消去可能な
情報記録方法に関する。 〔発明の背景〕 近年、情報記録の高密度化、デジタル化が進むにつれ
て種々の情報記録再生方式の開発が進められている。特
にレーザのエネルギーを情報の記録消去，再生に利用し
た光ディスクは鉱業レアメタルNo.80,1983（光ディスク
と材料）に記載されているように磁気ディスクに比べ、
高い記録密度が可能であり、今後の情報記録の有力な方
式である。このうち、レーザによる再生装置はコンパク
ト・ディスク（CD）として実用化されている。一方、記
録可能な方式には追記型と書き換え可能型の大きく２つ
に分けられる。前者は１回の書き込みのみが可能であ
り、消去はできない。後者はくり返しの記録，消去が可
能な方式である。追記型の記録方法はレーザ光により記
録部分の媒体を破壊あるいは成形して凹凸をつけ、再生
にはこの凹凸部分でのレーザ光の干渉による光反射量の
変化を利用する。この記録媒体にはTeやその合金を利用
して、その溶解，昇華による凹凸の成形が一般的に知ら
れている。この種の媒体では毒性など若干の問題を含ん
でいる。書き換え可能型の記録媒体としては光磁気材料
が主流である。この方法は光エネルギーを利用してキュ
リー点あるいは補償点温度付近で媒体の局部的な磁気異
方性を反転させ記録し、その部分での偏光入射光の磁気
ファラデー効果及びカー効果による偏光面の回転量にて
再生する。この方法は書き換え可能型の最も有望なもの
として数年後の実用化を目指し精力的な研究開発が進め
られている。しかし、現在のところ偏光面の回転量の大
きな材料がなく多層膜化などの種々の工夫をしてもS/N,
C/Nなどの出力レベルが小さいという大きな問題があ
る。その他の書き換え可能型方式として記録媒体の非晶
質と結晶質の可逆的相変化による反射率変化を利用した
ものがある。 例えばNational Technical Report Vol.29,No.5（198
3）p.82記載のTeOxに少量のゲルマニウム（Ge）、およ
び（Sn）を添加した薄膜はパワー密度が高くかつ短パル
スのレーザビームを照射することによって非晶質化しレ
ーザビームの非照射部よりも反射率を減少させることに
よって記録するものである。逆に消去はパワー密度の低
いレーザビームを照射して結晶化し記録部よりも反射率
を高くする方法で利用されている。 反射率の低い状態での記録の場合、例えばディスクに
ゴミ、ホコリなどが付着すると、これらは反射率を低下
させる方向にはたらく。したがって記録された信号はゴ
ミ、ホコリなどによって、信号レベルが低下することに
なる。 〔発明の目的〕 本発明の目的は、結晶構造変化を利用した記録媒体を
用い、高エネルギー投入後の状態で高反射率とし、高感
度の再生を可能にした情報記録方法を提供するにある。 〔発明の概要〕 本発明は、所定の強度の高エネルギーを投入後冷却し
た状態と前記強度より低い強度の低エネルギーを投入後
冷却した状態で異つた結晶構造を有する記録媒体への記
録方法において、高エネルギーを投入後冷却した状態の
分光反射率が低エネルギーを投入後冷却した状態の分光
反射率よりも高く変化させて情報を記録することを特徴
とする情報記録方法にある。 本発明に係る記録媒体は固相状態でエネルギーを投入
することにより、同一温度で少なくとも２種の反射率を
有し、可逆的に分光反射率を変えることができるもので
あって、とくに高エネルギーを投入後冷却した状態の分
光反射率が、低エネルギーを投入後冷却した状態の反射
率よりも高く変化できる記録媒体である。 また本発明において、高エネルギー投入後の反射率RW
が低エネルギー投入後の反射率REより大きくなる記録媒
体において、 RE＜RW＜γRE＋（１−γ）,0＜γ＜１ ……（１） （１）式を満足する時、記録，消去可能な記録媒体とな
る。ただし、γは低反射率状態と高反射率状態とを得る
ために必要な実効エネルギーの比である。 この関係は次のようにして導びかれる。すなわち外部
からの投入エネルギーＰと実際に媒体に投入された実効
エネルギーＱとの間には（２）式の関係がある。 Ｐ（１−Ｒ）＝Ｑ ……（２） 反射率Ｒの媒体ではＰ＊Ｒのエネルギーは反射され、
実際に媒体には投入されない。したがって、高エネルギ
ーを投入した状態の高反射率RWと、低エネルギーを投入
した状態の低反射率REとの間には、（３）式が成り立
つ。（３）式において、PWは高エネルギー投入時のエネ
ルギー、また、RWは該高エネルギーPWを投入した後の反
射率である。PEは低エネルギー投入時のエネルギー、ま
た、REは該低エネルギーPEを投入した後の反射率であ
る。 ここでPW＞PEなので （QW/（１−RE））＞（QE/（１−RW）） ゆえに、RW＜γRE＋（１−γ） ただし、γ＝QE/QW これより、（１）式を導くことができる。（１）式か
ら得られる範囲を第１図に示す。第１図の斜線部が記録
消去可能な状態である。 この場合、再生の出力が良好になることを考慮すると
RWとREとの反射率差が大きいことが望ましい。特にRW≧
1.3REの場合、特に良好な再生出力が得られ、大きなS/N
が得られる。この範囲は第１図中の部で示した。γはQE
とQWとの比であるが、実質的にはRW及びREの反射率が得
られる記録媒体の加熱温度と近似することができる。実
質的には反射率変化を起こすことができる温度として近
似できる。 本発明の記録媒体は上記関係が成り立つものに好適で
あるが、この中で結晶−結晶相転移を有する材料におい
ても好適である。 本発明の記録媒体は、周期律表のI b族元素の少なく
とも１種とII b族、III b族、IV b族及びV b族元素から
選ばれた少なくとも１種との合金からなるものが好まし
い。これらの合金のうち、銅を主成分とし、Al,Ga,In,G
e及びSnとの合金が好ましく、更にこれらの合金に第３
元素としてNi,Mn,Fe及びCrを含む合金が好ましい。 また、銀を主成分とし、Al,Cd及びZnを含む合金が好
ましく、更にこれらの合金に第３元素としてCu,Al,Auを
含有する合金が好ましい。 金を主成分とし、Alを含む合金が好ましい。 本発明合金は前記I b族元素とII b族、III b族、IV b
族及びV b族元素との金属間化合物を有するものが好ま
しい。 すなわち本発明に係る上記合金は固相状態で少なくと
も２つの温度領域で結晶構造の異なった相を有し、固相
状態での加熱冷却により同一温度で少なくとも２種の異
なる反射率を有し、可逆的に反射率を変えることができ
る。 本発明はトラッキング用溝が設けられた基板上に記録
媒体の薄膜が設けられるものに適用できる。 記録媒体は、固体状態において、室温より高い第１の
温度状態と、第１の温度よりも低い温度状態と、で異な
った結晶構造を有し、前記第１の温度状態から急冷する
ことによって、室温における平衡相の結晶構造とは異な
った結晶構造を採る、金属または合金で構成されること
が好ましい。 本発明にかかる合金は、高温の固相状態からの冷却の
仕方によって、分光反射率の異なる少なくとも２種の状
態を冷却後のある一の温度において有し、該２種の状態
間を可逆的に移行できるものである。すなわち、本発明
にかかる合金は、少なくとも２つの温度領域で、結晶構
造の異なった相を有し、それらのうち、高温相を急冷す
ることで得られる状態と、高温相を非急冷することで得
られる標準的な状態とで、分光反射率が異なる。そし
て、両状態間は、高温相温度領域での加熱急冷と、低温
相温度領域での加熱冷却と、によって可逆的に行き来で
きる。 以上述べた合金の相変化、分光率変化およびメカニズ
ムについて、第７図を用いてさらに具体的に説明する。 本発明の記録媒体に使用される材料における、分光反
射率の可逆的変化の原理を、第７図を用いて説明する。
第７図は、Ｘ−Ｙ二元系合金の状態図である。該合金に
は、α固溶体と、β金属間化合物と、γ金属間化合物と
が存在する。ここでは、組成ABXの合金を例にとって説
明を行う。該組成ABXの合金は、固相状態において、β
単相、（β＋γ）相と、（α＋γ）相と、のうちのいず
れかの状態をとりうる。α相、β相、γ相の結晶構造
は、それぞれ異なるため、これらβ単相、（β＋γ）相
と、（α＋γ）相とは、それぞれ光学的性質（例えば分
光反射率）も異なる。 第７図によれば、組成ABXの合金は、温度T1（一般的
には室温）では、（α＋γ）相が安定に存在し、また、
温度T4ではβ相が安定に存在することが示されている。
該組成ABXの合金を、温度T4まで加熱すると、該合金の
結晶構造はβ相となる。その後、急冷すると、（α＋
γ）相に移行することなくβ相のままで、温度T1に到
る。そのため、温度T1であっても、β相を採っている状
態と、（α＋γ）相を採っている状態とでは、分光反射
率が異なることとなる。 この温度T1、β相の状態にある該合金を、温度T2まで
加熱し、その後、冷却（注：急冷ではない）すると、該
合金は（α＋γ）相の状態に移行する。これにより、該
合金の分光反射率は、最初の状態に戻る。このように２
種類の加熱冷却処理を繰り返すことによって、分光反射
率の異なる２種類の状態間を可逆的に行き来することが
できる。 本発明の記録媒体の合金例は次の通りである。 銀を主成分とし、亜鉛30〜46wt％、アルミニウム６〜
10wt％の１種を含む合金、銅を主成分とし、アルミニウ
ム10〜20wt％、インジウム20〜40wt％、錫16〜35wt％の
１種を含む合金、金を主成分とし、アルミニウム2.5〜5
wt％を含む合金、又はこれらの合金に少量のVIII,I b,I
I b,III b,IV b,V b,VI a,VII a族の元素の１種以上を
含むことができる。その含有量は好ましくは10wt％以下
である。 記録密度として、20メガビット/cm2以上となるような
微小面積での情報の製作には0.01〜0.2μｍの膜厚とす
るのがよい。記録層として気相あるいは液相から直接急
冷固化させて所定の形状にすることが有効である。これ
らの方法にはPVD法（蒸着、スパッタリング法等）、CVD
法、溶湯を高速回転する高熱伝導性を有する部材からな
る。特に金属ロール円周面上に注湯して急冷凝固させる
溶湯急冷法、電気メッキ、化学メッキ法等がある。粉末
状の材料を利用する場合、基板上に塗布して基板上に接
着することが効果的である。塗布する場合、粉末を加熱
しても反応などを起こさないバインダーがよい。また、
加熱による材料の酸化等を防止するため、材料表面、基
板上に形成した膜あるいは塗布層表面をコーティングす
ることも有効である。 粉末は、溶湯を気体又は液体の冷媒とともに噴霧させ
て水中に投入させて急冷するガイアトマイズ法によって
形成させることが好ましい。その粒径は0.1mm以下が好
ましく、特に粒径１μｍ以下の超微粉が好ましい。 膜は前述の如く蒸着、スパッタリング、CVD電気メッ
キ、化学メッキ等によって形成できる。特に、0.1μｍ
以下の膜厚を形成するにはスパッタリングが好ましい。
スパッタリングは目標の合金組成のコントロールが容易
にできる。 （用途） 情報等の記録の手段として、電圧及び電流の形での電
気エネルギー、電磁波（可視光、輻射熱、赤外線、紫外
線、写真用閃光ランプの光、電子ビーム、陽子線、アル
ゴンレーザ、半導体レーザ等のレーザ光線、熱等）を用
いることができ、特にその照射による分光反射率の変化
を利用した光ディスクに利用するのが好ましい。光ディ
スクには、ディジタルオーディオディスク（DAD又はコ
ンパクトディスク）、ビデオディスク、メモリーディス
クなどがあり、これらに使用可能である。本発明の記録
媒体は再生専用型、追加記録型、書換型ディスク装置に
それぞれ使用でき、特に書換型ディスク装置においてき
わめて有効である。 本発明による光ディスクの記録及び再生の原理の例は
次の通りである。先ず、記録媒体を局部的に加熱、急冷
して高温度領域での結晶構造を低温度領域でも保持させ
ることで、所定の情報を記録する。あるいは、これとは
逆に、予め全体を高温相（高温度領域での結晶構造）に
しておき、これを局部的に加熱することで、高温相中に
局部的に低温相（低温度領域での結晶構造）を形成する
ことで記録する。記録部分に光を照射して加熱部分と非
加熱部分の光学的特性の差を検出して情報を再生するこ
とができる。更に情報として記録された部分を記録時の
加熱温度より低い温度又は高い温度で加熱し記録された
情報を消去することができる。光はレーザ光線が好まし
く、特に短波長レーザが好ましい。本発明の加熱部分と
非加熱部分との反射率が500nm又は800nm付近の波長にお
いて最も大きいので、このような波長を有するレーザ光
を再生に用いるのが好ましい。記録，再生には同じレー
ザ源が用いられ、消去に記録のものよりエネルギー密度
を小さくした他のレーザ光を照射するのが好ましい。 表示として、特に可視光での分光反射率を部分的に変
えることができるので塗料を使用せずに文字、図形、記
号等を記録することができ、それらの表示は目視によっ
て識別することができる。これらの情報は消去すること
ができ、記録と消去のくり返しのほか、永久保存も可能
である。 〔発明の実施例〕 （実施例１） 1.2mmtのSiO2ガラス基板に約100nm厚さの記録媒体を
スパッタリング法で作製した。この２層膜について、記
録媒体膜側からレーザ光を用いて記録し、ついで消去を
行なった。記録及び消去後、200〜1500nmの波長での分
光反射率の一例を第２図に示し、各種合金薄膜について
光源波長830nmにおける記録及び消去時の反射率（％）
を測定した結果を第１表に示す。記録温度が高いのは高
エネルギーの投入に相当し、消去温度が低い場合は低エ
ネルギーの投入に相当するが、第１表に示す合金薄膜は
すべて記録及び消去条件を満足した。表中の合金組成は
重量％である。記録時に記憶媒体の温度が記録時に要求
される所定温度に到達するようにレーザー光のパワーを
調節する。同様に、消去時には、記録媒体の温度を、消
去の際に要求される所定温度となるようにレーザー光を
ディフォーカスした。本実施例によれば、S/N比が高い
ものが得られる。 （実施例２） 記録媒体としてAg−40wt％Zn合金薄膜を用い、第２表
に示す膜構成でディスクを作製した。記録及び消去を83
0nmの波長の半導体レーザによって行い記録後及び消去
後の反射率を光源波長830nmの所で測定した。その結果
を第３図に示すが、No.1〜12までは記録及び消去条件を
満足した。この内でもとくにNo.8〜No.12までは最適な
特性を示した。なお、No.13は記録条件を満足したが、
消去条件を満足しなかった。しかしこのような場合でも
レーザ光の干渉膜としてTa2O5の膜厚を工夫して、No.5
のような状況にすると消去条件を満たすことができる。
この場合はTa2O5の膜厚を最適化することで、第４図の
ような干渉をおこさせ、記録後及び消去後の反射率を低
下できたためである。干渉が生じていることは、第４図
において、反射率が波長に応じて振動していることから
明らかである。なお第２表のNo.10〜12に示した熱吸収
膜としてCrOx膜を用いたものは第５図に示すように反射
率を低下させる効果と熱吸収の効果により、記録及び消
去条件を満足したものである。 記録及び消去温度は実施例１と同様の温度になるよう
にレーザ光を調節することによって行った。 （実施例３） 基板として1.2mmtのガラスを用い、記録膜として70nm
厚さのAg−40wt％Zn膜を用い、熱吸収層として10nm厚さ
のCrOxを透明層としてSiO2を200nm厚さにした第６図に
示すようなディスクを作製し、半導体レーザ５でガラス
基板１に形成された記録媒体について本発明の記録方法
としてその記録と消去とについてくり返し実施した結
果、何回でも問題なく、初期の特性が維持されることが
確認された。図中１はガラス基板、２は記録媒体、３は
熱吸収層、４は保ご膜としての透明層である。 〔発明の効果〕 本発明によれば、再生における感度が高く、容易に書
き換えできる情報の記録方法が得られる。The present invention relates to a recording medium having a higher spectral reflectance in a state where high energy is applied than in a state where low energy is applied, and The present invention relates to a method for recording erasable information on the recording medium. [Background of the Invention] In recent years, as information recording has become higher in density and digitized, various information recording / reproducing methods have been developed. In particular, optical disks that use laser energy for recording, erasing, and reproducing information are compared to magnetic disks, as described in Mining Rare Metals No. 80,1983 (optical disks and materials).
High recording density is possible, and it is a promising method for information recording in the future. Of these, the reproducing apparatus using a laser has been put to practical use as a compact disk (CD). On the other hand, the recordable methods are roughly classified into two types: a write-once type and a rewritable type. The former can only be written once and cannot be erased. The latter is a method that allows repeated recording and erasing. In the write-once recording method, the medium at the recording portion is destroyed or formed by laser light to form irregularities, and reproduction uses the change in the amount of light reflection due to the interference of the laser light at the irregularities. For this recording medium, it is generally known to use Te or an alloy thereof to form irregularities by melting and sublimation. This type of medium has some problems such as toxicity. Magneto-optical materials are mainly used as rewritable recording media. In this method, the local magnetic anisotropy of the medium is inverted near the Curie point or the compensation point temperature using light energy, and the recording is performed. Regenerate with the amount of rotation. This method is the most promising of the rewritable type, and vigorous R & D is being pursued with the aim of commercializing it in a few years. However, at present, there is no material with a large amount of rotation of the polarization plane, and S / N,
There is a big problem that the output level such as C / N is small. As another rewritable type system, there is a system that utilizes a change in reflectance due to a reversible phase change between amorphous and crystalline recording media. For example, National Technical Report Vol.29, No.5 (198
3) The thin film obtained by adding a small amount of germanium (Ge) and (Sn) to TeOx described on p. In this case, the recording is performed by reducing the reflectance. Conversely, erasing is used by irradiating a laser beam with a low power density to crystallize and raise the reflectance higher than that of the recording portion. In the case of recording in a state where the reflectance is low, for example, if dust or dust adheres to the disk, they act in a direction to lower the reflectance. Therefore, the signal level of the recorded signal decreases due to dust, dust and the like. [Object of the Invention] An object of the present invention is to provide an information recording method using a recording medium utilizing a change in crystal structure, having a high reflectance in a state after high energy input, and enabling high sensitivity reproduction. . [Summary of the Invention] The present invention relates to a method for recording on a recording medium having a different crystal structure in a state of cooling after inputting high energy of a predetermined intensity and a state of cooling after inputting low energy of lower intensity than the intensity. The information recording method is characterized in that information is recorded by changing the spectral reflectance in a state of cooling after inputting high energy to be higher than that in a state of cooling after inputting low energy. The recording medium according to the present invention has at least two kinds of reflectances at the same temperature by applying energy in a solid state, and can reversibly change the spectral reflectance. This is a recording medium in which the spectral reflectance in a state of cooling after inputting is higher than the reflectance in a state of cooling after inputting low energy. Further, in the present invention, the reflectance R W after high energy input
In the recording medium but larger than the reflectivity R E after low energy input, R E <R W <γRE + (1-γ), when satisfying 0 <γ <1 ...... (1 ) (1) wherein the recording , An erasable recording medium. Here, γ is the ratio of the effective energy required to obtain the low reflectance state and the high reflectance state. This relationship is derived as follows. That is, there is a relationship of the formula (2) between the externally input energy P and the effective energy Q actually input to the medium. P (1-R) = Q (2) In a medium having a reflectance R, energy of P * R is reflected,
It is not actually put into the medium. Therefore, a high reflectivity R W in a state where charged with high energy, between the low reflectivity R E of state was charged with low energy, (3) it holds. (3) In the equation, P W is the energy in the high energy input also,, R W is reflectance after switching on the high-energy P W. P E is the energy at low energy input, also, R E is the reflectance after switching on the low energy P E. Here, since P W > P E, (Q W / (1−R E ))> (Q E / (1−R W )) Therefore, R W <γR E + (1−γ) where γ = Q E / Q W From this, equation (1) can be derived. FIG. 1 shows the range obtained from equation (1). A hatched portion in FIG. 1 indicates a state where recording and erasing are possible. In this case, considering that the output of reproduction becomes good
It is desirable reflectance difference between the R W and R E is large. In particular, R W ≧
In the case of 1.3R E , particularly good reproduction output is obtained and large S / N
Is obtained. This range is shown by the part in FIG. γ is Q E
And is a ratio of the Q W, in effect can be approximated with the heating temperature of the recording medium the reflectivity of R W and R E are obtained. Substantially, it can be approximated as a temperature at which a change in reflectance can occur. The recording medium of the present invention is suitable for those in which the above relationship is satisfied, but is also suitable for a material having a crystal-crystal phase transition. The recording medium of the present invention comprises an alloy of at least one element selected from Group Ib of the periodic table and at least one element selected from Group IIb, Group IIIb, Group IVb and Group Vb. preferable. Of these alloys, copper is the main component, and Al, Ga, In, G
Alloys with e and Sn are preferred, and these alloys have a third
Alloys containing Ni, Mn, Fe and Cr as elements are preferred. Further, an alloy containing silver as a main component and containing Al, Cd and Zn is preferable, and an alloy containing Cu, Al and Au as a third element in these alloys is preferable. An alloy mainly containing gold and containing Al is preferable. The alloy of the present invention comprises the group Ib element and the group IIb, group IIIb, group IVb
Those having an intermetallic compound with a Group V or Group Vb element are preferred. That is, the alloy according to the present invention has a phase having a different crystal structure in at least two temperature ranges in a solid state, has at least two different reflectivities at the same temperature by heating and cooling in a solid state, The reflectance can be changed reversibly. The present invention can be applied to an apparatus in which a thin film of a recording medium is provided on a substrate provided with a tracking groove. In the solid state, the recording medium has different crystal structures in a first temperature state higher than room temperature and a temperature state lower than the first temperature, and is rapidly cooled from the first temperature state. It is preferable to use a metal or an alloy that has a crystal structure different from the crystal structure of the equilibrium phase at room temperature. The alloy according to the present invention has, at a certain temperature after cooling, at least two states having different spectral reflectances depending on how to cool from a high-temperature solid state, and reversibly switches between the two states. Can be transferred to That is, the alloy according to the present invention has phases having different crystal structures in at least two temperature ranges. Of these, a state obtained by rapidly cooling the high-temperature phase and a state obtained by non-quenching the high-temperature phase. The spectral reflectance differs from the standard state obtained. Then, the two states can be reversibly switched by rapid heating and cooling in the high-temperature phase temperature region and heating and cooling in the low-temperature phase temperature region. The phase change, spectral change, and mechanism of the alloy described above will be described more specifically with reference to FIG. The principle of the reversible change in the spectral reflectance of the material used for the recording medium of the present invention will be described with reference to FIG.
FIG. 7 is a phase diagram of an XY binary alloy. The alloy includes an α solid solution, a β intermetallic compound, and a γ intermetallic compound. Here, a description of the alloy composition AB X as an example. The alloy of the composition AB X in the solid state has β
It can take any one of a single phase, a (β + γ) phase, and a (α + γ) phase. Since the α, β, and γ phases have different crystal structures, the β single phase, (β + γ) phase, and (α + γ) phase also have different optical properties (for example, spectral reflectance). According to FIG. 7, the alloy having the composition AB X has a stable (α + γ) phase at the temperature T 1 (generally room temperature),
In the temperature T 4 beta-phase is shown to exist stably.
The alloy of the composition AB X, when heated to a temperature T 4, the crystal structure of the alloy becomes β phase. Then, when quenched, (α +
remain in β-phase without shifting the gamma) phase, leading to the temperature T 1. Therefore, even at a temperature T 1, and the state adopts a β-phase, in a state in which taking the (alpha + gamma) phase, so that the spectral reflectance is different. When the alloy in the temperature T 1 , β phase state is heated to the temperature T 2 and then cooled (note: not quenched), the alloy transitions to the (α + γ) phase state. Thereby, the spectral reflectance of the alloy returns to the initial state. Thus 2
By repeating the types of heating and cooling processes, it is possible to reversibly switch between two types of states having different spectral reflectances. The alloy examples of the recording medium of the present invention are as follows. Main component is silver, zinc is 30 ~ 46wt%, aluminum is 6 ~
Alloy containing 10wt% of one kind, alloy mainly containing copper, alloy containing one kind of aluminum 10 ~ 20wt%, indium 20 ~ 40wt%, tin 16 ~ 35wt%, mainly containing gold, aluminum 2.5 ~ 5
wt%, or a small amount of VIII, Ib, I
It may include one or more of the elements of groups Ib, IIIb, IVb, Vb, VIa, VIIa. Its content is preferably at most 10% by weight. In order to produce information with a very small area such that the recording density is 20 megabits / cm 2 or more, the film thickness is preferably 0.01 to 0.2 μm. It is effective that the recording layer is directly cooled and solidified from a gas phase or a liquid phase into a predetermined shape. These methods include PVD (evaporation, sputtering, etc.), CVD
The method consists of a member having high thermal conductivity that rotates the molten metal at high speed. In particular, there are a molten metal quenching method in which a molten metal is poured onto a circumferential surface of a metal roll and rapidly solidified, an electroplating method, a chemical plating method and the like. When a powdery material is used, it is effective to apply it on a substrate and adhere it to the substrate. When applying, a binder that does not cause a reaction or the like even when the powder is heated is preferable. Also,
In order to prevent the material from being oxidized due to heating, it is also effective to coat the surface of the material, the film formed on the substrate or the surface of the coating layer. The powder is preferably formed by a gait atomizing method in which a molten metal is sprayed together with a gas or liquid refrigerant, the molten metal is injected into water, and quenched. The particle size is preferably 0.1 mm or less, particularly preferably ultrafine powder having a particle size of 1 μm or less. The film can be formed by vapor deposition, sputtering, CVD electroplating, chemical plating or the like as described above. In particular, 0.1 μm
Sputtering is preferred for forming the following film thickness.
Sputtering can easily control the target alloy composition. (Applications) As means for recording information and the like, electric energy in the form of voltage and current, electromagnetic waves (visible light, radiant heat, infrared rays, ultraviolet rays, light from photographic flash lamps, electron beams, proton beams, argon lasers, semiconductor lasers) Laser light, heat, etc.), and it is particularly preferable to use an optical disc utilizing a change in spectral reflectance due to the irradiation. The optical disk includes a digital audio disk (DAD or compact disk), a video disk, a memory disk, and the like, and can be used for these. The recording medium of the present invention can be used for each of a read-only type, an additional recording type, and a rewritable disk device, and is particularly effective for a rewritable disk device. An example of the principle of recording and reproduction of the optical disk according to the present invention is as follows. First, predetermined information is recorded by locally heating and rapidly cooling the recording medium to maintain the crystal structure in the high temperature region even in the low temperature region. Alternatively, conversely, the whole may be made into a high-temperature phase (crystal structure in a high-temperature region) in advance and locally heated to locally form a low-temperature phase (in a low-temperature region) in the high-temperature phase. Is recorded by forming the crystal structure). By irradiating the recording portion with light, a difference in optical characteristics between the heated portion and the non-heated portion can be detected to reproduce information. Further, the part recorded as information can be heated at a temperature lower or higher than the heating temperature at the time of recording to erase the recorded information. The light is preferably a laser beam, particularly preferably a short wavelength laser. Since the reflectance of the heated portion and the unheated portion of the present invention is the largest at a wavelength near 500 nm or 800 nm, it is preferable to use laser light having such a wavelength for reproduction. The same laser source is used for recording and reproduction, and it is preferable to irradiate another laser beam having a lower energy density than that of the recording for erasing. As the display, in particular, it is possible to partially change the spectral reflectance in visible light, so that characters, figures, symbols, etc. can be recorded without using paint, and those displays can be visually identified. . This information can be erased and can be recorded and erased repeatedly, as well as permanently stored. [Examples of the Invention] (Example 1) A recording medium having a thickness of about 100 nm was formed on a 1.2 mmt SiO 2 glass substrate by a sputtering method. This two-layer film was recorded from the recording medium film side using a laser beam, and then erased. FIG. 2 shows an example of the spectral reflectance at a wavelength of 200 to 1500 nm after recording and erasing, and the reflectance (%) at recording and erasing at a light source wavelength of 830 nm for various alloy thin films.
Table 1 shows the measurement results. A high recording temperature corresponds to high energy input, and a low erasing temperature corresponds to low energy input. All alloy thin films shown in Table 1 satisfy the recording and erasing conditions. The alloy composition in the table is% by weight. The power of the laser beam is adjusted so that the temperature of the storage medium at the time of recording reaches a predetermined temperature required at the time of recording. Similarly, at the time of erasing, the laser beam was defocused so that the temperature of the recording medium became a predetermined temperature required at the time of erasing. According to the present embodiment, a high S / N ratio can be obtained. (Example 2) A disk was produced with a film configuration shown in Table 2 using an Ag-40 wt% Zn alloy thin film as a recording medium. 83 record and erase
The reflectance after recording and after erasing was measured at a light source wavelength of 830 nm using a semiconductor laser having a wavelength of 0 nm. The results are shown in FIG. 3, and the recording and erasing conditions were satisfied for Nos. 1 to 12. Among them, No. 8 to No. 12 showed the optimum characteristics. No. 13 satisfied the recording conditions,
The erase condition was not satisfied. However, even in such a case, the thickness of Ta 2 O 5 was devised as an interference film of the laser beam, and No. 5
In such a situation, the erasing condition can be satisfied.
In this case, by optimizing the thickness of Ta 2 O 5 , interference as shown in FIG. 4 was caused, and the reflectance after recording and after erasing could be reduced. The occurrence of the interference is apparent from the fact that the reflectance oscillates according to the wavelength in FIG. In addition, those using a CrOx film as the heat absorbing film shown in Nos. 10 to 12 in Table 2 satisfy the recording and erasing conditions due to the effect of lowering the reflectance and the effect of heat absorption as shown in FIG. It was done. The recording and erasing temperatures were adjusted by adjusting the laser light so that the temperatures were the same as in Example 1. (Example 3) 1.2 mmt glass was used as a substrate, and 70 nm was used as a recording film.
A disk as shown in FIG. 6 was prepared using an Ag-40 wt% Zn film having a thickness of 10 nm and a transparent layer of CrOx having a thickness of 200 nm and SiO 2 having a thickness of 200 nm as a heat absorbing layer. As a result of repeating the recording and erasing of the recording medium formed on the substrate 1 as the recording method of the present invention, it was confirmed that the initial characteristics were maintained without any problem many times. In the figure, 1 is a glass substrate, 2 is a recording medium, 3 is a heat absorbing layer, and 4 is a transparent layer as a protective film. [Effects of the Invention] According to the present invention, it is possible to obtain a method of recording information which has high sensitivity in reproduction and can be easily rewritten.

【図面の簡単な説明】 第１図は記録消去時の分光反射率の関係を示す線図、第
２図は本発明の記録方法による分光反射率特性を示す線
図、第３図は本発明に係る合金膜の記録・消去時の分光
反射率の関係を示す線図、第４図は干渉膜を有した本発
明の記録方法による分光反射率特性を示す線図、第５図
は熱吸収膜を有する本発明の記録方法による分光反射率
特性を示す線図、第６図は本発明の記録方法に用いたデ
ィスクの一例を示す断面図、第７図は本発明の記録方法
に用いた記録媒体の合金の一例を示す二元状態図であ
る。 １……基板、２……記録媒体、３……熱吸収層、４……
透明層、５……レーザ光。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between the spectral reflectances at the time of recording and erasing, FIG. 2 is a diagram showing the spectral reflectance characteristics according to the recording method of the present invention, and FIG. FIG. 4 is a graph showing the relationship between the spectral reflectances of the alloy film according to the present invention at the time of recording / erasing, FIG. 4 is a graph showing the spectral reflectance characteristics of the recording method of the present invention having an interference film, and FIG. FIG. 6 is a diagram showing the spectral reflectance characteristics of the recording method of the present invention having a film, FIG. 6 is a sectional view showing an example of a disk used in the recording method of the present invention, and FIG. FIG. 3 is a binary phase diagram illustrating an example of an alloy of a recording medium. 1 ... substrate 2 ... recording medium 3 ... heat absorption layer 4 ...
Transparent layer, 5 ... laser light.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 安藤 寿 日立市幸町３丁目１番１号 株式会社日 立製作所日立研究所内 (72)発明者 伊藤 鉄男 日立市幸町３丁目１番１号 株式会社日 立製作所日立研究所内 (72)発明者 永井 正一 日立市幸町３丁目１番１号 株式会社日 立製作所日立研究所内 (72)発明者 渡辺 隆二 日立市幸町３丁目１番１号 株式会社日 立製作所日立研究所内 (72)発明者 清水 誠喜 日立市幸町３丁目１番１号 株式会社日 立製作所日立研究所内 (56)参考文献 特開 昭59−144049（ＪＰ，Ａ)   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hisashi Ando               3-1-1, Sachimachi, Hitachi               Inside Hitachi Research Laboratory (72) Inventor Tetsuo Ito               3-1-1, Sachimachi, Hitachi               Inside Hitachi Research Laboratory (72) Inventor Shoichi Nagai               3-1-1, Sachimachi, Hitachi               Inside Hitachi Research Laboratory (72) Inventor Ryuji Watanabe               3-1-1, Sachimachi, Hitachi               Inside Hitachi Research Laboratory (72) Inventor Seiki Shimizu               3-1-1, Sachimachi, Hitachi               Inside Hitachi Research Laboratory                (56) References JP-A-59-144049 (JP, A)

Claims (1)

(57)【特許請求の範囲】 １．基板と、該基板上に設けられた記録媒体膜とを有
し、 前記記録媒体膜は、その性質として、結晶構造の異なる
第１の相と第２の相とをとり得、前記第２の相は、第１
の温度に達するまでエネルギーの投入を受けた場合、前
記第１の相に変化し、当該第１の相は、前記第１の温度
よりも低い第２の温度に達するまでエネルギーの投入を
受けた場合、前記第２の相に変化するものであり、 前記第１の相の再生に使用する波長の光についての反射
率は、前記第２の相の前記波長の光についての反射率よ
り高く、前記第２の相から第１の相への変化によって情
報を記録し、前記第１の相から第２の相への変化によっ
て前記情報を消去することを特徴とする光ディスク。 ２．特許請求の範囲第１項に記載の光ディスクにおい
て、前記第１の相の前記再生に使用する波長の光につい
ての反射率をRW、前記第２の相の前記再生に使用する波
長の光についての反射率をREとした場合、RWとREは、 RW≧1.3RE の関係を満たすことを特徴とする光ディスク。 ３．再生光の波長において、第１の反射率を有する第１
の相と、前記第１の反射率よりも低い第２の反射率を有
する第２の相とをとり得、前記第２の相は、第１の温度
に達するまでエネルギーの投入を受けた場合、前記第１
の相に変化し、当該第１の相は、前記第１の温度よりも
低い第２の温度に達するまでエネルギーの投入を受けた
場合、前記第２の相に変化する性質の記録媒体を用い、 前記記録媒体の前記第２の相に前記第１の温度に達する
までエネルギーを投入し、前記第２の相を前記第１の相
に変化させることにより情報を記録し、前記記録媒体の
前記第１の相に前記第２の温度に達するまでエネルギー
を投入し、前記第１の相を前記第２の相に変化させるこ
とにより情報を消去することを特徴とする情報記録方
法。(57) [Claims] A substrate, and a recording medium film provided on the substrate, wherein the recording medium film can have, as its properties, a first phase and a second phase having different crystal structures; Phase 1
Changes to the first phase when energy is input until the temperature reaches the first temperature, and the first phase receives energy input until the second temperature lower than the first temperature is reached. In the case, it is changed to the second phase, the reflectance for the light of the wavelength used for reproduction of the first phase is higher than the reflectance for the light of the wavelength of the second phase, An optical disc, wherein information is recorded by a change from the second phase to a first phase, and the information is erased by a change from the first phase to a second phase. 2. An optical disk according to paragraph 1 claims, the reflectivity R W for light of a wavelength to be used for the reproduction of the first phase, the light of the wavelength to be used for the reproduction of the second phase If the reflectance of the set to R E, R W and R E is an optical disc characterized by satisfying the relationship of R W ≧ 1.3R E. 3. At the wavelength of the reproduction light, the first light having the first reflectance
And a second phase having a second reflectance lower than the first reflectance, wherein the second phase receives energy input until a first temperature is reached. , The first
And the first phase uses a recording medium having a property of changing to the second phase when energy is input until the first temperature reaches a second temperature lower than the first temperature. Energy is applied to the second phase of the recording medium until the first temperature is reached, and information is recorded by changing the second phase to the first phase. An information recording method, wherein energy is supplied to a first phase until the temperature reaches the second temperature, and information is erased by changing the first phase to the second phase.
JP59251889A 1984-11-29 1984-11-30 Optical disc and information recording method Expired - Fee Related JP2910767B2 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
JP59251889A JP2910767B2 (en) 1984-11-30 1984-11-30 Optical disc and information recording method
US06/801,950 US4651172A (en) 1984-11-29 1985-11-26 Information recording medium
CA000496335A CA1238489A (en) 1984-11-29 1985-11-27 Information recording medium
EP85308665A EP0186329B1 (en) 1984-11-29 1985-11-28 Information recording medium
DE8585308665T DE3583599D1 (en) 1984-11-29 1985-11-28 INFORMATION RECORDING MEDIUM.
KR1019850008929A KR920001263B1 (en) 1984-11-29 1985-11-29 Recording and removing method of information

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59251889A JP2910767B2 (en) 1984-11-30 1984-11-30 Optical disc and information recording method

Related Child Applications (1)

Application Number Title Priority Date Filing Date
JP10143337A Division JP3034497B2 (en) 1998-05-25 1998-05-25 Information recording / reproducing / erasing device

Publications (2)

Publication Number Publication Date
JPS61131235A JPS61131235A (en) 1986-06-18
JP2910767B2 true JP2910767B2 (en) 1999-06-23

Family

ID=17229451

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59251889A Expired - Fee Related JP2910767B2 (en) 1984-11-29 1984-11-30 Optical disc and information recording method

Country Status (1)

Country Link
JP (1) JP2910767B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0243976B1 (en) * 1986-05-02 1996-09-04 Hitachi, Ltd. Method for recording, reproducing and erasing information and thin film for recording information

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59144049A (en) * 1983-02-07 1984-08-17 Matsushita Electric Ind Co Ltd Optical recording and reproducing system

Also Published As

Publication number Publication date
JPS61131235A (en) 1986-06-18

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