JPS6369048A - Optical recording medium - Google Patents
Optical recording mediumInfo
- Publication number
- JPS6369048A JPS6369048A JP61214332A JP21433286A JPS6369048A JP S6369048 A JPS6369048 A JP S6369048A JP 61214332 A JP61214332 A JP 61214332A JP 21433286 A JP21433286 A JP 21433286A JP S6369048 A JPS6369048 A JP S6369048A
- Authority
- JP
- Japan
- Prior art keywords
- optical recording
- nitride
- thickness
- medium
- 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 16
- 239000011347 resin Substances 0.000 claims abstract description 22
- 229920005989 resin Polymers 0.000 claims abstract description 22
- 239000000758 substrate Substances 0.000 claims abstract description 13
- 239000010419 fine particle Substances 0.000 claims description 14
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 239000002131 composite material Substances 0.000 abstract description 10
- 239000004417 polycarbonate Substances 0.000 abstract description 8
- 229920000515 polycarbonate Polymers 0.000 abstract description 8
- 239000002245 particle Substances 0.000 abstract description 5
- 239000011248 coating agent Substances 0.000 abstract description 2
- 238000000576 coating method Methods 0.000 abstract description 2
- 150000004767 nitrides Chemical class 0.000 abstract 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract 4
- 238000003848 UV Light-Curing Methods 0.000 abstract 3
- 229910052681 coesite Inorganic materials 0.000 abstract 2
- 229910052906 cristobalite Inorganic materials 0.000 abstract 2
- 239000000377 silicon dioxide Substances 0.000 abstract 2
- 235000012239 silicon dioxide Nutrition 0.000 abstract 2
- 229910052682 stishovite Inorganic materials 0.000 abstract 2
- 229910052905 tridymite Inorganic materials 0.000 abstract 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 6
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 239000011859 microparticle Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- -1 rare-earth transition metal Chemical class 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
Landscapes
- Optical Record Carriers And Manufacture Thereof (AREA)
Abstract
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は光記録媒体の構造に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of an optical recording medium.
光学的に記録−再生あるいは消去可能な光記録媒体は、
従来より研究開発がさかんにおこなわれてきた。特に近
年磁気光学効果金利用した光磁気記録媒体は、消去書き
換え可能な光記、録媒体として実用化寸前の状態である
。ところが、光磁気記録媒体の記録膜（は希土類遷移金
属膜であるため、耐候性に劣っていた。そこで本発明者
らは鋭意研究努力の結果、保護膜である誘電体膜の複合
化（特願昭６ｌ−７４７９４）、及び貼合せ構造（％願
昭６１−１２２７６７ ）の開発を経て実用に十分材え
うる長期信頼性のある光磁気記録媒体を提供できるよう
になつ念。Optical recording media that can be optically recorded, reproduced or erased are:
Research and development has been actively conducted. In particular, in recent years, magneto-optical recording media using magneto-optic gold are on the verge of being put into practical use as erasable and rewritable optical recording media. However, since the recording film of magneto-optical recording media is a rare-earth transition metal film, it has poor weather resistance.Thus, as a result of intensive research efforts, the present inventors have developed a composite dielectric film (specially Through the development of the patent application No. 61-74794) and the laminated structure (No. 61-122767), we hope to be able to provide magneto-optical recording media with sufficient long-term reliability for practical use.
しかし前述の従来技術では、長期信頼性のある媒体は提
供できる様になったが、基板に透光性樹脂基板（ＰＣ，
ＰＭＭＡ、エポキシ樹脂等）を用いているため、湿度温
度膨張が大力・＜一度書き込んだ信号のズレ（ジッター
）が大きくなるという重大な欠点を有していた。そこで
以前は、加速試験音おこなう場合、媒体を恒温恒湿槽か
ら取り出し１昼夜常温湿下に放置しておかなければなら
なかった。However, with the above-mentioned conventional technology, it has become possible to provide a medium with long-term reliability, but the substrate is a translucent resin substrate (PC,
PMMA, epoxy resin, etc.), it had serious drawbacks such as large humidity and temperature expansion and increased signal deviation (jitter) once written. Previously, when conducting accelerated sound testing, it was necessary to take the medium out of the constant temperature and humidity chamber and leave it at room temperature and humidity all day and night.
さらに、基板表面は透光性樹脂が露出しているため耐擦
傷性が悪く、すぐ傷ついてしまうという欠点を有してい
た。Furthermore, since the transparent resin is exposed on the surface of the substrate, it has poor scratch resistance and is easily scratched.
そこで本発明はこのような問題点を解決するもので、そ
の目的とするところは、使用環境湿度の変化があっても
信号のジッター量の変化が無く、しかも傷つきにくい光
記録媒体を提供するところにある。The present invention is intended to solve these problems, and its purpose is to provide an optical recording medium that does not change the amount of signal jitter even when the humidity of the environment in which it is used changes, and that is not easily damaged. It is in.
透光性樹脂基板上に形成しｔ光記録ｊａに、光を照射し
記録・再生あるいは消去全行う光記録媒体において、光
記録媒体の外界と接触する部位を、誘電体微粒子が含有
された紫外線硬化樹脂で被覆したことを特徴とする。In an optical recording medium formed on a transparent resin substrate and in which recording, reproduction, or erasing is performed by irradiating the optical recording medium with light, the portion of the optical recording medium that comes into contact with the outside world is exposed to ultraviolet light containing dielectric fine particles. It is characterized by being coated with a hardened resin.
本発明の上記構成によれば、光記録媒体の外界と接触す
る部位を、誘電体微粒子入り紫外線硬化樹脂で被覆する
ことによう、透光性樹脂箔版内への湿気（水分）の侵入
全防止する。さらに媒体全被覆している紫外線硬化樹脂
は誘電体（セラミック〕を含有している几め熱膨張率が
小さく、透光性樹脂基板の熱膨張全押え込むことにより
信号のジッター量の変化を無くすることができるのであ
る。そして、媒体表面硬度も増すことから耐擦傷性が向
上する。According to the above structure of the present invention, the portion of the optical recording medium that comes into contact with the outside world is coated with the ultraviolet curing resin containing dielectric fine particles, thereby preventing moisture (moisture) from penetrating into the translucent resin foil plate. To prevent. Furthermore, the ultraviolet curable resin that covers the entire medium has a small coefficient of thermal expansion because it contains a dielectric (ceramic), and by suppressing all of the thermal expansion of the translucent resin substrate, changes in the amount of jitter in the signal are eliminated. Furthermore, since the medium surface hardness also increases, the scratch resistance improves.
以下本発明を実施例をもとに詳述する。The present invention will be described in detail below based on examples.
第１図は、本発明の光磁気記録媒体の断面概略図である
。１は案内溝付きポリカーボネート（ｐｃ）基板であり
、この上に２として窒化アルミニウムと窒化シリコンの
複合誘電体膜１０００Ａｉスパツタ法にて成膜しく以下
成膜は全てスパッタ法）、そして３のＮｄＤｙＦｅ０ｏ
Ｔｉ光磁気記録膜４００Ａｉ成膜し、さらに４の窒化ア
ルミニウムと窒化シリコンの複合誘電体膜１０００Ａ’
ｉ成膜し九〇次に５の溝無しｐｃ基板上に６の窒化アル
ミニウムと窒化シリコンの複合酵電体膜５００Ａｉ成膜
し、これら成膜された案内溝付３ｐｃ基板と溝無しＰＣ
基板全７の紫外線（Ｕ／Ｖ ）硬化樹脂を用いて密着貼
合せした。そして最後に、この貼合せ光磁気記録媒体の
外界と接している部位全面を８として５１０２微粒子入
り紫外線硬化樹脂層を塗布し被覆した。膜みは１５μｍ
厚であシ、ＢＬＯ２微粒子は５０Ｖｏｔ％入っている。FIG. 1 is a schematic cross-sectional view of the magneto-optical recording medium of the present invention. 1 is a polycarbonate (PC) substrate with guide grooves, on which a composite dielectric film 2 of aluminum nitride and silicon nitride of 1000Ai is formed by sputtering (all films are formed by sputtering), and 3 NdDyFe0o.
A Ti magneto-optical recording film of 400 Ai was formed, and a composite dielectric film of 4 aluminum nitride and silicon nitride of 1000 A' was formed.
90 Next, 500Ai composite electrolyte film of aluminum nitride and silicon nitride was formed on the grooveless PC board of No. 5, and these films were formed on the 3PC substrate with guide grooves and the PC without groove.
All seven substrates were closely bonded using ultraviolet (U/V) curing resin. Finally, the entire surface of the bonded magneto-optical recording medium in contact with the outside world was coated with an ultraviolet curable resin layer containing 5102 fine particles. Film thickness is 15μm
It is thick and contains 50Vot% of BLO2 fine particles.
この様にして作成した本発明媒体と、被覆無し従米媒体
全用い、記録・再生しその信号のジッター量を見た。記
録時の温度は２５℃湿度は５０％である。そして、これ
らの本発明及び従来の媒体を２５℃一定の条件にし、湿
度を変えてそのジッター量の変化を見たのが第２図であ
り、ジッター量の湿度依存性図である。２１が本発明に
よる８１０□微粒子入り紫外線硬化樹脂被覆有媒体、２
２が従来の被覆無し媒体であり、この図より明らかなよ
うに本発明媒体のジッターは湿度によらず５０ｎθθＣ
と一定であるが、従来媒体は湿度の変化とともジッター
は増加する、これは湿度膨張（収縮）に併う信号のズレ
が生じ之ためである。The amount of jitter in the signal was measured by recording and reproducing the medium of the present invention prepared in this way and the uncoated conventional American medium. The temperature during recording was 25° C. and the humidity was 50%. FIG. 2 is a diagram showing the humidity dependence of the jitter amount when the media of the present invention and the conventional media are kept at a constant temperature of 25° C. and the humidity is changed to see the changes in the amount of jitter. 21 is 810□ microparticle-containing ultraviolet curing resin coated medium according to the present invention, 2
2 is a conventional uncoated medium, and as is clear from this figure, the jitter of the present invention medium is 50nθθC regardless of humidity.
However, in conventional media, the jitter increases as the humidity changes. This is because a signal shift occurs due to humidity expansion (contraction).
几だし湿度５０ＣＸ時のジッターは本発明媒体と同じ３
０ ｎＢ＠Ｑであるが、これは、記録時の湿度が５０Ｘ
であった念めである。Jitter at reduced humidity of 50CX is 3, the same as the inventive media.
0 nB@Q, but this is because the humidity at the time of recording is 50X
This is a reminder.
次に、これら２つの媒体を絶対湿度一定にして、温度上
昇させてジッター量を測定したものが第３図であり、ジ
ッター量の温度依存性図である。Next, the jitter amount of these two media was measured by raising the temperature while keeping the absolute humidity constant, and FIG. 3 shows the temperature dependence of the jitter amount.
２１′が本発明被覆有媒体、２２′が従来の被覆無し媒
体である。この図からも明らかな様に本発明媒体はジッ
ター量の変化が少ないことがわかる。21' is a coated medium of the present invention, and 22' is a conventional uncoated medium. As is clear from this figure, it can be seen that the medium of the present invention shows little change in the amount of jitter.
−万、従来の媒体はジッター量に大きな温度依存性があ
ることがわかる。本発明媒体と従来媒体のジッター量か
２５℃で同じでおるのは、記録時の温度が２５℃である
念めである。- It can be seen that the amount of jitter in conventional media has a large temperature dependence. The reason why the amount of jitter between the medium of the present invention and the conventional medium is the same at 25°C is due to the fact that the recording temperature is 25°C.
これら第２図及び第３図より本発明媒体は、外部環境の
温湿度変化に対して極めて安定した媒体であることがわ
かる。It can be seen from these FIGS. 2 and 3 that the medium of the present invention is extremely stable against changes in temperature and humidity in the external environment.
次に、Ｓｉｎ、微粒子入り紫外線硬化樹脂の５１０２微
粒子ｉｋ変えた媒体全種々用意しく塗布厚は１５μｍ一
定とし之）、ジッター量の温度上昇による変化を見た。Next, we examined the changes in the amount of jitter due to temperature rise using a variety of media (with a constant coating thickness of 15 μm) using different types of media, including Sin and 5102 microparticles of ultraviolet curable resin containing microparticles.
つまり、２５℃で記録し念信号全８０℃で再生しジッタ
ー量を測定した。That is, the amount of jitter was measured by recording at 25°C and reproducing the signal at a total temperature of 80°C.
第４図かそれで、ジッター量の８１０を微粒子量依存性
図である。横軸が微粒子ｔ （Ｖｏｔ％）である。FIG. 4 is a diagram showing the dependence of the jitter amount 810 on the amount of fine particles. The horizontal axis is the fine particles t (Vot%).
この図に示し念ものは、微粒子量が８０ ＶｏｔＸＯも
のまでであるが、これは８０ Ｖｏｔ％を超える含有率
の紫外線硬化樹脂は均一に塗布できない之めである。What is important to note in this figure is that the amount of fine particles is up to 80 VotXO, but this is because an ultraviolet curable resin having a content exceeding 80 Vot% cannot be uniformly coated.
この図よシ、微粒子量がｚｖｏｚＸ以上であればジッタ
ー量の温度依存性がないことがわかる。しかし２７ｏｔ
％未満でも、その効果は大きい。This figure shows that if the amount of fine particles is zvozX or more, there is no temperature dependence of the amount of jitter. But 27ot
Even if it is less than %, the effect is large.
本実施例に用い之全ての８１０．微粒子の平均粒径は１
０００Ａである。そして、本発明媒体の表面硬度は、鉛
筆硬度で２Ｈとなり、従来の被覆無し媒体のＢ−ＨＢと
比較して耐擦傷性が向上した。All 810. used in this example. The average particle size of fine particles is 1
It is 000A. The surface hardness of the medium of the present invention was 2H on a pencil hardness, and the scratch resistance was improved compared to the conventional uncoated medium B-HB.
伺、本実施例に用いた紫外線硬化樹脂に含有する誘電体
はＳ１０．であるが、Ｓｉｎ、に限定されるものでなく
Ａｌｔｏｚ 、 Ｃ！ａＦ！、 ＯｅＦ、 ＫＢｒ、
Ｋｃ４ＬａＦ１ 、 ＮｄＦｌ 、 ８１０． Ｔｈ
Ｆ４． ＷＯｓ、 ０ｓＢｒ。The dielectric material contained in the ultraviolet curing resin used in this example was S10. However, it is not limited to Sin, Altoz, C! aF! , OeF, KBr,
Kc4LaF1, NdFl, 810. Th
F4. WOs, 0sBr.
Ｃ８工、 ＭｇＯ，ＮａＦ、 Ｔｈｅ、 、 ＭｇＦ！
、 ＡｔＮ、 Ｂｉ、＠Ｎ、 。C8 Engineering, MgO, NaF, The, , MgF!
, AtN, Bi, @N, .
８１Ｎ、ＺｎＳ、ＳｉＣ！、ＴｉＮ等の微粒子あるいは
それらの混合の微粒子を用いても何らさしつかえない。81N, ZnS, SiC! There is no problem in using fine particles such as , TiN, or a mixture thereof.
又、平均粒径も１０００Ａに限定されるものでな（１０
０Ａ径、１μｍ径等でも何ら問題ない。Also, the average particle size is not limited to 1000A (10
There is no problem with a diameter of 0A, a diameter of 1 μm, etc.
さらに、本実施例に用いた記録媒体の構造は密着貼合せ
構造であるが、エアーサンドインチ構造及び単板でも本
発明は有効であり、又光磁気記録媒体でなく、追記型光
記録媒体にも本発明は有効でるる。さらに、本実施例の
記録層側の構造は、光磁気記録層を誘電体膜でサンドイ
ンチする３層構造であるが、これ以外の反射膜をさらに
つけ念４層構造あるいは、３層目の誘電体膜を反射膜に
かえた３層構造のものでも有効である。Furthermore, although the structure of the recording medium used in this example is a closely bonded structure, the present invention is also effective with an air sandwich structure and a single plate, and is applicable to write-once optical recording media instead of magneto-optical recording media. The present invention is also effective. Furthermore, the structure on the recording layer side of this example is a three-layer structure in which the magneto-optical recording layer is sandwiched between dielectric films, but it is possible to add a reflective film other than this to a four-layer structure or a third layer structure. A three-layer structure in which the dielectric film is replaced with a reflective film is also effective.
以上述べたように本発明によれば、光記録媒体の外界と
接触する部位を誘電体微粒子が含有された紫外線硬化樹
脂で被覆したことにより、外部環境の温湿度変化に対し
信号のジッターｉｋヲ少なくでき、ひいてはＢｉ −１
−’Ｆ、ｒｒｏｒ Ｒａｔθの変化も少なくできる。又
、基板表面が硬くなることから耐擦傷性も向上する。As described above, according to the present invention, the part of the optical recording medium that contacts the outside world is coated with an ultraviolet curable resin containing dielectric fine particles, thereby reducing signal jitter and noise due to changes in temperature and humidity in the external environment. Bi -1
-'F, rror Changes in Ratθ can also be reduced. Furthermore, since the substrate surface becomes hard, scratch resistance is also improved.
第１図は、本発明の光磁気記録媒体の断面概略図。
第２図は、ジッター量の湿度依存性図。
第３図は、ジッター量の温度依存性図。
第４図は、ジッター量の８１０！微粒子量依存性図。
１・・・案内溝付きポリカーボネート（ＰＣ）基板２・
・・窒化アルミニウムと窒化シリコンの複合誘電体膜１
０００Ａ厚
３−・−ＮｄＤｙＦ’ｅＣｏＴｉ光磁気記録膜４００Ａ
厚４・・・窒化アルミニウムと窒化シリコンの複合誘電
体膜１０００Ａ厚
５・・・溝無しｐｃ基板
６・・・窒化アルミニウムと窒化シリコンの複合誘電体
膜５００Ａ厚
７・・・紫外線（Ｕ／Ｖ ）硬化樹脂層８・・・Ｓｉｎ
、微粒子入り紫外線硬化樹脂層２１・・・本発明による
Ｓ１０．被覆布媒体２２・・・従来の被覆無し媒体
２１’・・・本発明によるＳ１０．被覆布媒体２２′・
・・従来の被覆無し媒体。
第 ２ 図
易３図FIG. 1 is a schematic cross-sectional view of the magneto-optical recording medium of the present invention. FIG. 2 is a humidity dependence diagram of the amount of jitter. FIG. 3 is a temperature dependence diagram of the amount of jitter. Figure 4 shows the jitter amount of 810! Fine particle amount dependence diagram. 1... Polycarbonate (PC) board with guide groove 2.
...Composite dielectric film of aluminum nitride and silicon nitride 1
000A thickness 3--NdDyF'eCoTi magneto-optical recording film 400A
Thickness 4... Composite dielectric film of aluminum nitride and silicon nitride 1000A Thickness 5... Grooveless PC board 6... Composite dielectric film of aluminum nitride and silicon nitride 500A Thickness 7... Ultraviolet (U/V) ) Cured resin layer 8...Sin
, fine particle-containing ultraviolet curable resin layer 21...S10. according to the present invention. Covered cloth medium 22...Conventional uncoated medium 21'...S10. according to the present invention. Covered cloth medium 22'・
...Conventional uncoated media. Part 2 Diagram 3
Claims (1)
録・再生あるいは消去を行う光記録媒体において、前記
光記録媒体の外界と接触する部位を、誘電体微粒子が含
有された紫外線硬化樹脂で被覆したことを特徴とする光
記録媒体。In an optical recording medium in which recording, reproduction, or erasing is performed by irradiating an optical recording layer formed on a transparent resin substrate with light, the portion of the optical recording medium that comes into contact with the outside world is exposed to ultraviolet light containing dielectric fine particles. An optical recording medium characterized by being coated with a cured resin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61214332A JPH0754591B2 (en) | 1986-09-11 | 1986-09-11 | Optical recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61214332A JPH0754591B2 (en) | 1986-09-11 | 1986-09-11 | Optical recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6369048A true JPS6369048A (en) | 1988-03-29 |
| JPH0754591B2 JPH0754591B2 (en) | 1995-06-07 |
Family
ID=16654000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61214332A Expired - Lifetime JPH0754591B2 (en) | 1986-09-11 | 1986-09-11 | Optical recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0754591B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6430041A (en) * | 1987-07-24 | 1989-01-31 | Hitachi Ltd | Optical disk |
| JPH03132935A (en) * | 1989-10-18 | 1991-06-06 | Hitachi Ltd | Optical disk |
| WO1991016708A1 (en) * | 1990-04-17 | 1991-10-31 | Mitsui Petrochemical Industries, Ltd. | Production method of magnetooptical recording medium and magnetooptical recording medium |
| US5490131A (en) * | 1990-07-20 | 1996-02-06 | Sharp Kabushiki Kaisha | Optical disk |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5859254A (en) * | 1981-10-02 | 1983-04-08 | Asahi Glass Co Ltd | Transparent plastic material |
| JPS5862841A (en) * | 1981-10-09 | 1983-04-14 | Seiko Epson Corp | Disc material |
-
1986
- 1986-09-11 JP JP61214332A patent/JPH0754591B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5859254A (en) * | 1981-10-02 | 1983-04-08 | Asahi Glass Co Ltd | Transparent plastic material |
| JPS5862841A (en) * | 1981-10-09 | 1983-04-14 | Seiko Epson Corp | Disc material |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6430041A (en) * | 1987-07-24 | 1989-01-31 | Hitachi Ltd | Optical disk |
| JPH03132935A (en) * | 1989-10-18 | 1991-06-06 | Hitachi Ltd | Optical disk |
| WO1991016708A1 (en) * | 1990-04-17 | 1991-10-31 | Mitsui Petrochemical Industries, Ltd. | Production method of magnetooptical recording medium and magnetooptical recording medium |
| US5490131A (en) * | 1990-07-20 | 1996-02-06 | Sharp Kabushiki Kaisha | Optical disk |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0754591B2 (en) | 1995-06-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |