JPH0544739B2 - - Google Patents

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Publication number
JPH0544739B2
JPH0544739B2 JP59064213A JP6421384A JPH0544739B2 JP H0544739 B2 JPH0544739 B2 JP H0544739B2 JP 59064213 A JP59064213 A JP 59064213A JP 6421384 A JP6421384 A JP 6421384A JP H0544739 B2 JPH0544739 B2 JP H0544739B2
Authority
JP
Japan
Prior art keywords
layer
light
recording medium
light absorption
recording
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 - Lifetime
Application number
JP59064213A
Other languages
Japanese (ja)
Other versions
JPS60209940A (en
Inventor
Nobutoshi Asai
Shinichiro Tamura
Nobuyoshi Seto
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.)
Sony Corp
Original Assignee
Sony Corp
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 Sony Corp filed Critical Sony Corp
Priority to JP59064213A priority Critical patent/JPS60209940A/en
Publication of JPS60209940A publication Critical patent/JPS60209940A/en
Publication of JPH0544739B2 publication Critical patent/JPH0544739B2/ja
Granted 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
    • G11B7/244—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 organic materials only
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/258—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
    • G11B7/2531—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising glass

Landscapes

  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Manufacturing Optical Record Carriers (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

産業上の利用分野 本発明は光学式記録媒体に関する。 背景技術とその問題点 透明な基板と光吸収層と光反射層とからなる光
学式記録媒体において、記録感度および記録信号
の変調度を改善するために干渉効果を利用する方
法は、光吸収層がTeなどの金属薄膜である場合、
あるいは光磁気記録媒体においてよく研究されて
いる（例えば、A.E.Bell、F.W.Spong、IEEE、
J.Quantum Electronics14、p.487）。 光吸収層が光吸収性有機材料あるいは光吸収物
質を分散させた高分子結合剤を用いて形成されて
いる場合、光吸収層は一般に屈折率が1.5に近く、
また吸光度も比較的小さいため、記録感度を向上
させるためには層の厚さをレーザ光の波長程度に
厚くする必要がある。この場合、光吸収層が空気
に面するように構成された光記録媒体では、光吸
収層の２つの界面から反射される光の位相を打ち
消し合うように光吸収層の厚さを調整すれば、こ
の層での吸光率が向上し、反射率が低下して、記
録感度が改善される（例えば、K.Y.Law；Appl.
Phys.Lett.36(11)p.884；D.G.Howe and J.J.
Wrobel、J.Vac.Sci.Technol.18(1)p.92）。しかし、
光吸収層（記録面）を保護するために保護層を設
けたり、あるいは基板を通して記録再生を行う場
合、屈折率が1.5に近い光吸収層は、屈折率がや
はり1.5程度の基板または保護層に面するために、
界面では反射はほとんど起こらず、干渉効果が得
られない。なお、基板または保護層に接する光吸
収層の界面に金属コーテイング層を設ければ、強
い干渉効果は得られるが、金属自身の光吸収が大
きいため好ましくない。 発明の目的 本発明は、前記の点に鑑み、強い干渉効果が得
られ、記録感度および記録信号の変調度が改善さ
れた光学式記録媒体を提供するものである。 発明の概要 本発明の光学式記録媒体は、透明基板と、第１
反射層と、光吸収層と、第２反射層とが積層され
てなり、前記光吸収層は第１反射層と第２反射層
との間にあり、前記第１反射層は光入射側にあつ
て前記透明基板および前記光吸収層の各屈折率よ
り大きい屈折率を有する材料を用いて厚さがλ／4n （１＋2m）（ここで、λはレーザ光の波長、ｎは
第１反射層の屈折率、ｍは０または正の整数を表
わす）であるように形成されている。 このように構成された本発明の光学式記録媒体
においては、第１反射層と光吸収層との界面にお
ける光の反射率が増大しかつ強い干渉効果が得ら
れ、記録感度と記録信号の変調度が大きく改善さ
れる。 実施例 以下、本発明の光学式記録媒体の実施例につき
図面を参照しながら説明する。 第１図は本実施例による記録媒体１の構造を示
す断面図である。記録媒体１は、ガラスを材料と
して作られた厚さ0.2mm、屈折率1.5の基板２を有
する。基板２の片面には反射率強化コーテイング
層として、厚さ860Å、屈折率2.3のZnS蒸着膜の
第１反射層３が設けられている。第１反射層３の
露出面上には記録層としての光吸収層４が設けら
れている。この光吸収層４は、700nｍ以上の波
長域に高い吸収特性を示す次式 のスピロピラン化合物、即ち5′−メトキシ−1′−
ｎ−ヘキシル−3′，3′−ジメチル−６−ニトロ−
８−メトキシスピロ〔2H−１−ペンゾチオピラ
ン−２，2′−インドリン〕と塩化ビニル−塩化ビ
ニリデン共重合体（電気化学工業社製デンカビニ
ル＃1000W）とを重量比１：２で混合し、溶剤
（テトラヒドロフラン：シクロヘキサノン＝１：
１）に溶解させてスピンナ塗布により形成させた
層であり、厚さ0.7μｍおよび屈折率1.5である。
光吸収層４は紫外線照射により発色し、波長780
〜800nｍの半導体レーザ光を吸収して記録を行
い、可視光照射あるいは加熱により消色する。 光吸収層４の露出面上には光反射層として、厚
さ1000Å、屈折率0.085〜i5.35のAg蒸着層の第２
反射層５が設けられている。 このように構成された記録媒体１の諸特性を測
定するため、基板２側から紫外線を照射して光吸
収層４を発色させた。このためには、500W超高
圧水銀灯（ウシオ電気社製）を用い、東芝製フイ
ルター（UV−36C、IRA−25S）を通して360nｍ
付近の紫外線を選択的に照射した。照度は約15ｍ
Ｗ／cm2である。次に、この発色した光吸収層４に
基板２側から半導体レーザ光を照射した。 比較例として、第１図の記録媒体１における第
１反射層３が設けられていないこと以外は前記記
録媒体１と同じ様に構成された記録媒体６（第２
図）についても、前記と同様に紫外線および半導
体レーザ光の照射を行つた。各記録媒体の特性と
して次の結果を得た。 １ 紫外線照射時間に対する半導体レーザ光の反
射率変化（第３図および第４図） 紫外線の照射時間を０、５、15、60秒と変化
させて、光吸収層４でのスピロピ／ラ発色に伴
うレレーザ光の各波長における反射率の変化を
測定し、第３図に本実施例の記録媒体１による
結果を実線で、比較例の記録媒体６による結果
を点線で示した。 第３図から明らかなように、記録媒体１は記
録媒体６に比べて、少ない紫外線照射量で波長
780〜800nｍ付近の反射率が低下し、半導体レ
ーザ光がより吸収され易くなつていることがわ
かる。逆に、記録媒体１は600〜700nｍ付近で
反射率の低下が少なく、この波長範囲の光が吸
収されにくくなつている。 また、第３図における波長780nｍでの反射
率変化を、紫外線照射時間に対してプロツトし
て第４図に示した。第４図からも本実施例の記
録媒体１が比較例の記録媒体６に比べて少ない
紫外線照射量で反射率の低下が大きいことが明
らかである。 ２ 記録感度（第５図） 記録媒体１および６の各試料に前記と同様の
紫外線を照射して光吸収層４を発色させ、次い
で半導体レーザ光を照射し、この照射（記録）
前後の反射率変化を測定した。 記録条件：レーザ光の波長＝780nｍ レーザパワー＝９ｍＷ（試料上） レーザビーム直径＝1.2μｍ（半値幅） パルス幅＝0.1〜7μs 得られた結果を第５図に示す。 第５図から明らかなように、本実施例の記録
媒体１は比較例の記録媒体６に比べて、小さな
エネルギーで大きな反射率変化が得られ、例え
ば反射率変化20％を得るためのエネルギー密度
は第１表に示す通り、比較例の場合の約1/2に
なつている。なお、この結果は各試料につい
て、光吸収層４の発色条件をいろいろに変えて
測定したうちの最良の場合を比較したもので、
第１表にそのときの紫外線照射量と記録前の反
射率が示してある。 FIELD OF INDUSTRIAL APPLICATION The present invention relates to optical recording media. BACKGROUND TECHNOLOGY AND PROBLEMS There is a method of utilizing interference effects to improve recording sensitivity and modulation degree of recorded signals in an optical recording medium consisting of a transparent substrate, a light absorption layer, and a light reflection layer. When is a metal thin film such as Te,
Or magneto-optical recording media are well studied (e.g. AEBell, FWSpong, IEEE,
J.Quantum Electronics 14 , p.487). When the light-absorbing layer is formed using a light-absorbing organic material or a polymeric binder in which a light-absorbing substance is dispersed, the light-absorbing layer generally has a refractive index close to 1.5.
Furthermore, since the absorbance is relatively low, in order to improve the recording sensitivity, it is necessary to increase the thickness of the layer to about the wavelength of the laser beam. In this case, in an optical recording medium configured such that the light absorption layer faces the air, the thickness of the light absorption layer may be adjusted so that the phases of the light reflected from the two interfaces of the light absorption layer cancel each other out. , the absorbance in this layer increases, the reflectance decreases, and the recording sensitivity improves (e.g. KYLaw; Appl.
Phys.Lett. 36 (11)p.884; D.G. Howe and JJ
Wrobel, J.Vac.Sci.Technol. 18 (1)p.92). but,
When providing a protective layer to protect the light absorption layer (recording surface) or recording and reproducing through a substrate, the light absorption layer with a refractive index close to 1.5 is placed on a substrate or protective layer that also has a refractive index of about 1.5. In order to face
Almost no reflection occurs at the interface, and no interference effect is obtained. Note that if a metal coating layer is provided at the interface of the light absorption layer in contact with the substrate or the protective layer, a strong interference effect can be obtained, but this is not preferable because the metal itself has a large light absorption. OBJECTS OF THE INVENTION In view of the above points, the present invention provides an optical recording medium that provides a strong interference effect and has improved recording sensitivity and modulation degree of recorded signals. Summary of the Invention The optical recording medium of the present invention includes a transparent substrate, a first
A reflective layer, a light absorbing layer, and a second reflective layer are laminated, the light absorbing layer is between the first reflective layer and the second reflective layer, and the first reflective layer is on the light incident side. A material having a refractive index larger than each of the transparent substrate and the light absorption layer is used so that the thickness is λ/4n (1+2m) (where λ is the wavelength of the laser beam, and n is the first reflective layer). m is 0 or a positive integer). In the optical recording medium of the present invention configured in this way, the light reflectance at the interface between the first reflective layer and the light absorption layer increases and a strong interference effect is obtained, which improves the recording sensitivity and the modulation of the recording signal. degree is greatly improved. Examples Examples of the optical recording medium of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a recording medium 1 according to this embodiment. The recording medium 1 has a substrate 2 made of glass with a thickness of 0.2 mm and a refractive index of 1.5. On one side of the substrate 2, a first reflective layer 3 of a ZnS vapor-deposited film with a thickness of 860 Å and a refractive index of 2.3 is provided as a reflectance-enhancing coating layer. A light absorption layer 4 as a recording layer is provided on the exposed surface of the first reflective layer 3. This light absorption layer 4 has the following formula showing high absorption characteristics in the wavelength range of 700 nm or more. spiropyran compound, i.e. 5'-methoxy-1'-
n-hexyl-3',3'-dimethyl-6-nitro-
8-Methoxyspiro [2H-1-penzothiopyran-2,2'-indoline] and vinyl chloride-vinylidene chloride copolymer (Denkabinil #1000W manufactured by Denki Kagaku Kogyo Co., Ltd.) were mixed at a weight ratio of 1:2, and a solvent ( Tetrahydrofuran: Cyclohexanone = 1:
This layer is formed by dissolving 1) and coating with a spinner, and has a thickness of 0.7 μm and a refractive index of 1.5.
The light absorption layer 4 develops color by UV irradiation, and has a wavelength of 780.
Recording is performed by absorbing semiconductor laser light of ~800 nm, and the color is erased by visible light irradiation or heating. On the exposed surface of the light absorption layer 4, a second Ag vapor deposited layer with a thickness of 1000 Å and a refractive index of 0.085 to i5.35 is formed as a light reflection layer.
A reflective layer 5 is provided. In order to measure various characteristics of the recording medium 1 configured as described above, ultraviolet rays were irradiated from the substrate 2 side to cause the light absorption layer 4 to develop color. For this purpose, a 500W ultra-high pressure mercury lamp (manufactured by Ushio Electric) was used, and a 360nm light was passed through a Toshiba filter (UV-36C, IRA-25S).
Selectively irradiated nearby areas with ultraviolet light. Illuminance is about 15m
W/ cm2 . Next, this colored light absorption layer 4 was irradiated with semiconductor laser light from the substrate 2 side. As a comparative example, a recording medium 6 (a second
2) was also irradiated with ultraviolet rays and semiconductor laser light in the same manner as above. The following results were obtained regarding the characteristics of each recording medium. 1 Change in reflectance of semiconductor laser light with respect to ultraviolet irradiation time (Figures 3 and 4) By changing the ultraviolet ray irradiation time to 0, 5, 15, and 60 seconds, the spiropy/la color development in the light absorption layer 4 was observed. Changes in reflectance at each wavelength of the accompanying laser light were measured, and in FIG. 3, the results for the recording medium 1 of this example are shown by a solid line, and the results for the recording medium 6 of the comparative example are shown by a dotted line. As is clear from FIG. 3, compared to recording medium 6, recording medium 1 requires a smaller amount of ultraviolet irradiation and wavelengths.
It can be seen that the reflectance in the vicinity of 780 to 800 nm decreases, and the semiconductor laser light is more easily absorbed. On the contrary, in the recording medium 1, the decrease in reflectance is small in the vicinity of 600 to 700 nm, and light in this wavelength range is difficult to be absorbed. Further, the change in reflectance at a wavelength of 780 nm in FIG. 3 is plotted against the ultraviolet irradiation time and is shown in FIG. It is also clear from FIG. 4 that the reflectance of the recording medium 1 of this example is significantly reduced by a smaller amount of ultraviolet irradiation than the recording medium 6 of the comparative example. 2 Recording sensitivity (Fig. 5) Each sample of recording media 1 and 6 is irradiated with ultraviolet rays similar to those described above to cause the light absorption layer 4 to develop color, and then irradiated with semiconductor laser light, and this irradiation (recording)
Changes in reflectance before and after were measured. Recording conditions: Laser light wavelength = 780 nm Laser power = 9 mW (on sample) Laser beam diameter = 1.2 μm (half width) Pulse width = 0.1 to 7 μs The obtained results are shown in FIG. As is clear from FIG. 5, compared to the recording medium 6 of the comparative example, the recording medium 1 of this example can obtain a large change in reflectance with a small amount of energy; for example, the energy density required to obtain a change in reflectance of 20% is As shown in Table 1, it is about 1/2 of that of the comparative example. Note that these results are a comparison of the best cases measured for each sample under various color development conditions of the light absorption layer 4.
Table 1 shows the amount of ultraviolet irradiation and the reflectance before recording.

【表】 本実施例の記録媒体１による記録感度の向上
は、第１反射層３と光吸収層４との界面での反射
率を高めたことにより、光吸収層４と第２反射層
５の界面からの光と強い干渉を起こし、入射した
レーザ光が光吸収層４に一層集中し、反射する光
量が減少するためであると考えられる。 本実施例において、さらに、基板２の厚さを変
えた以外は記録媒体１および６の各種構成を有す
る光デイスクを次のように作製し、キヤリアの記
録、再生特性を測定した。 光デイスクの形状：直径８cm；ガラス製基板厚さ
＝1.3mm；プリグループなし。 記録条件：（紫外線（360nｍ）照射量：1.0J／cm2）
基板側からレーザ光照射；レーザ光の波長＝
780nｍ；レーザパワー＝８ｍＷ（試料上）；レ
ンズNA＝0.5；キヤリア周波数1MHz；デユー
テイ比50％の方形波使用；記録線速度＝2.6
ｍ／ｓ；記録波長＝2.6μｍ；トラツクピツチ＝
約5μｍ。 こうして記録された各光デイスクから、家庭用
コンパクトデイスクプレーヤを利用した再生装置
により得られた再生信号（デイスク１周分）のエ
ンベロープは第６図（実施例の光デイスク；曲線
ａとｂとで示す）および第７図（比較例の光デイ
スク；曲線ｃとｄとで示す）の通りであつた。こ
れらの図において、縦軸の0.5V単位は反射率で
20％に相当する。本実施例の構成を有する光デイ
スクのエンベロープは比較例の光デイスクのエン
ベロープに比べて信号振幅が約２倍であり、キヤ
リアレベルが6dB向上していることがわかる。 第１反射層は、屈折率が通常のガラス、高分子
樹脂などの屈折率と大きく異なる方が効果的であ
り、また透明であることが好ましく、前記実施例
におけるZnSの他に、TiO2、ZrO2、Y2O3などの
蒸着膜を用いることができる。また、第１反射層
は、厚さがλ／4n（１＋2m）（ただし、λ、ｎおよ びｍは前記と同じ意味を有する）の単層構造の他
に、膜厚λ／4n（１＋2m）の高屈折率層と低屈折率 層とを交互に重ねた多層構造であつてもよい。な
お前記ｍの値は特に制限はないが、実用上０〜３
の整数であるのが好ましい。 第２反射層は、本発明において屈折率が1.5に
近い材料で効果が高く、スピロピラン化合物の他
に各種の色素、金属微粒子などを高分子結合剤に
分散させて得た材料を使用することができる。 基板は第１反射層に面しているか、あるいは第
２反射層に面しているか、いずれでもよい。 発明の効果 光学式記録媒体において、光吸収層が従来の反
射層と本発明における新規な反射率強化層との間
に存在するように構成することにより、光吸収層
における記録感度の向上した光学式記録媒体を得
ることができる。また、光吸収層がスピロピラン
系フオトクロミツク化合物を材料として形成され
ている場合、記録に先立つて必要な発色のための
紫外線の量を減少させることができ、光吸収層が
長寿命化し、書き換え回数が増加した光学式記録
媒体を得ることができる。さらに、記録媒体の吸
光度変化だけでなく、屈折率変化や体積変化記録
再生方式においても反射率を大きく変化させるこ
とができる。また、レーザ光の波長以外の波長の
光に対しては、光吸収層の吸光率が低くなるの
で、光化学的変化に基づく記録媒体では記録の保
存性を向上させることができる。[Table] The recording sensitivity of the recording medium 1 of this embodiment was improved by increasing the reflectance at the interface between the first reflective layer 3 and the light absorbing layer 4. It is thought that this is because strong interference occurs with light from the interface, and the incident laser light is further concentrated on the light absorption layer 4, reducing the amount of reflected light. In this example, optical disks having various configurations of the recording media 1 and 6 except that the thickness of the substrate 2 was changed were fabricated as follows, and the recording and reproducing characteristics of the carriers were measured. Optical disk shape: diameter 8cm; glass substrate thickness = 1.3mm; no pregroup. Recording conditions: (Ultraviolet (360nm) irradiation amount: 1.0J/cm 2 )
Laser light irradiation from the substrate side; wavelength of laser light =
780 nm; Laser power = 8 mW (on sample); Lens NA = 0.5; Carrier frequency 1 MHz; Use of square wave with duty ratio of 50%; Recording linear velocity = 2.6
m/s; recording wavelength = 2.6 μm; track pitch =
Approximately 5μm. The envelope of the playback signal (one round of the disk) obtained from each optical disk recorded in this way by a playback device using a household compact disk player is shown in FIG. 6 (optical disk of the example; curves a and b). ) and FIG. 7 (optical disk of comparative example; shown by curves c and d). In these figures, the 0.5V unit on the vertical axis is the reflectance.
Equivalent to 20%. It can be seen that the envelope of the optical disk having the configuration of this example has a signal amplitude approximately twice that of the envelope of the optical disk of the comparative example, and the carrier level is improved by 6 dB. The first reflective layer is more effective if its refractive index is significantly different from that of ordinary glass, polymer resin, etc., and is preferably transparent. A deposited film of ZrO 2 , Y 2 O 3 or the like can be used. In addition, the first reflective layer has a single-layer structure with a thickness of λ/4n (1+2m) (where λ, n, and m have the same meanings as above), or a single-layer structure with a thickness of λ/4n (1+2m). It may have a multilayer structure in which high refractive index layers and low refractive index layers are alternately stacked. Note that the value of m is not particularly limited, but in practice it is 0 to 3.
Preferably, it is an integer of . In the present invention, the second reflective layer is highly effective with a material with a refractive index close to 1.5, and in addition to spiropyran compounds, materials obtained by dispersing various pigments, metal fine particles, etc. in a polymeric binder can also be used. can. The substrate may face either the first reflective layer or the second reflective layer. Effects of the Invention In an optical recording medium, by configuring the light absorption layer to exist between the conventional reflection layer and the novel reflectance-enhancing layer of the present invention, an optical recording medium with improved recording sensitivity in the light absorption layer can be obtained. A type recording medium can be obtained. In addition, when the light absorption layer is made of a spiropyran-based photochromic compound, the amount of ultraviolet rays required for color development prior to recording can be reduced, the life of the light absorption layer is extended, and the number of rewrites is reduced. Increased optical recording media can be obtained. Furthermore, the reflectance can be greatly changed not only by changing the absorbance of the recording medium but also by changing the refractive index or by changing the volume of the recording/reproducing method. Further, since the absorbance of the light absorption layer is low for light having a wavelength other than the wavelength of laser light, the storage stability of recording can be improved in a recording medium based on photochemical change.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例の光学式記録媒体の
構成、第２図は比較例の光学式記録媒体の構成、
第３図〜第５図はレーザ光の反射率変化、第６図
は本発明の一実施例の光デイスクによる再生信号
のエンベロープおよび第７図は比較例の光デイス
クによる再生信号のエンベロープを示す。 なお図面に用いられた符号において、１……記
録媒体、２……基板、３……第１反射層、４……
光吸収層、５……第２反射層、６……記録媒体で
ある。 FIG. 1 shows the configuration of an optical recording medium according to an embodiment of the present invention, and FIG. 2 shows the configuration of an optical recording medium according to a comparative example.
Figures 3 to 5 show changes in the reflectance of laser light, Figure 6 shows the envelope of the reproduced signal from an optical disk according to an embodiment of the present invention, and Figure 7 shows the envelope of the reproduced signal from an optical disk according to a comparative example. . In addition, in the symbols used in the drawings, 1... recording medium, 2... substrate, 3... first reflective layer, 4...
Light absorption layer, 5... second reflective layer, 6... recording medium.

Claims (1)

【特許請求の範囲】 １ 透明基板と、第１反射層と、光吸収層と、第
２反射層とが積層されてなり、前記光吸収層は第
１反射層と第２反射層との間にあり、前記第１反
射層は光入射側にあつて前記透明基板および前記
光吸収層の各屈折率より大きい屈折率を有する材
料を用いて厚さがλ／4n（１＋2m）（ここで、λは レーザ光の波長、ｎは第１反射層の屈折率、ｍは
０または正の整数を表わす）であるように形成さ
れてなることを特徴とする光学式記録媒体。[Claims] 1. A transparent substrate, a first reflective layer, a light absorption layer, and a second reflective layer are laminated, and the light absorption layer is located between the first reflective layer and the second reflective layer. The first reflective layer is located on the light incident side and is made of a material having a refractive index larger than each of the transparent substrate and the light absorption layer, and has a thickness of λ/4n (1+2 m) (here, λ is the wavelength of the laser beam, n is the refractive index of the first reflective layer, and m is 0 or a positive integer.
JP59064213A 1984-03-31 1984-03-31 Optical recording medium Granted JPS60209940A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59064213A JPS60209940A (en) 1984-03-31 1984-03-31 Optical recording medium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59064213A JPS60209940A (en) 1984-03-31 1984-03-31 Optical recording medium

Publications (2)

Publication Number Publication Date
JPS60209940A JPS60209940A (en) 1985-10-22
JPH0544739B2 true JPH0544739B2 (en) 1993-07-07

Family

ID=13251579

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59064213A Granted JPS60209940A (en) 1984-03-31 1984-03-31 Optical recording medium

Country Status (1)

Country Link
JP (1) JPS60209940A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08315422A (en) * 1995-05-15 1996-11-29 Nec Corp Optical recording medium

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4101907A (en) * 1977-08-29 1978-07-18 Rca Corporation Overcoat structure for optical video disc
JPS5778649A (en) * 1980-10-30 1982-05-17 Teijin Ltd Laminated material for optical memory
JPS586541A (en) * 1981-07-02 1983-01-14 Sharp Corp Magnetooptic storage element
JPS598150A (en) * 1982-07-02 1984-01-17 Sharp Corp Magnetooptical storage element
JPH0226299A (en) * 1988-07-15 1990-01-29 Matsushita Electric Works Ltd Stepping motor

Also Published As

Publication number Publication date
JPS60209940A (en) 1985-10-22

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