JPH0443332B2 - - Google Patents
Info
- Publication number
- JPH0443332B2 JPH0443332B2 JP59171906A JP17190684A JPH0443332B2 JP H0443332 B2 JPH0443332 B2 JP H0443332B2 JP 59171906 A JP59171906 A JP 59171906A JP 17190684 A JP17190684 A JP 17190684A JP H0443332 B2 JPH0443332 B2 JP H0443332B2
- Authority
- JP
- Japan
- Prior art keywords
- adhesive
- optical
- optical disk
- mixable
- bonded together
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 27
- 239000000758 substrate Substances 0.000 claims description 25
- 239000000853 adhesive Substances 0.000 claims description 23
- 230000001070 adhesive effect Effects 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 2
- 239000010408 film Substances 0.000 description 19
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 8
- 239000012790 adhesive layer Substances 0.000 description 8
- 230000001681 protective effect Effects 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000004528 spin coating Methods 0.000 description 4
- 239000003522 acrylic cement Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000007650 screen-printing Methods 0.000 description 3
- 239000004831 Hot glue Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000007759 kiss coating Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
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
Landscapes
- Manufacturing Optical Record Carriers (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
Description
産業上の利用分野
本発明は、レーザー記録用の光デイスクとその
接着法に関するものである。
従来例の構成とその問題点
レーザー記録用デイスク（以後、光デイスクと
称する）は、直径30cm足らずの円盤上にA4文書
が１万枚分以上も記憶できるほどの大容量のメモ
リー媒体であり、一つのビツトはわずか1μｍ前
後の長さの小さなピツトに対応している。また、
情報の書き込み、読み出しなどは、１分間に1000
回転以上の高速回転しているデイスク上に、直径
1μｍ前後に絞り込んだレーザー光を集光し、位
置検出、焦点調節を行ないながら実行されるもの
であり、極くわずかな基板のソリ、平行度のズ
レ、変形、傷、異物なども、信号エラーにつなが
つてしまう。このため、光デイスクの製造には、
半導体製造時から劣らない程度、細心の注意が要
求されている。光デイスクは従来、信頼性を高め
る目的から、第２図に示すように、レーザー記録
用薄膜３を２枚の透明基板１，２の間にはさみ込
んだ構成となつている。（但し、第１図は光デイ
スクを切断した斜視図であり、以下、断面の一部
Ａを拡大して積層状態を説明する。第２図におい
ては、片面記録用光デイスクの例を示す。）この
ため、これら２枚の透明基板１，２を接着層４を
介して貼り合わせる接着工程が重要であり、この
工程により歩留りや光デイスクの信頼性が左右さ
れることも多い。
従来、この接着法としてはホツトメルト系接着
剤を用いる方式が知られているが、この方法は、
熱と圧力とが同時に加わるため、基板のソリや歪
み傷つきや気泡などが発生しやすく、しかも、記
録膜によつては、熱影響による変質なども発生し
ており、加えて、高湿度下では接着力低下による
剥離も生じるなど、多くの問題点を有していた。
発明の目的
本発明は、上述した従来の接着法の欠点を解決
するものであり、高性能を要求される光デイスク
の接着工程を短時間に能率的に行ない、かつ、工
程上、高温を要さぬため、記録膜への影響もな
く、さらに、強い接着力を与えるため高湿度下に
長時間放置しても剥離を生じないような優れた光
デイスクの接着法を提供することを目的としてい
る。
発明の構成
本発明の光デイスク接着法は、２枚のプラスチ
ツク製透明基板を貼り合わせる構成の光デイスク
板のそれぞれの基板の貼り合わせようとする面上
に、二液非混合型接着剤の混合前の二成分を別々
に塗り分け、接着剤塗布同志を重ね合わせて後、
硬化してなるというものであり、これにより上述
の目的を達成せんとするものである。
実施例の説明
具体例を説明する前に本発明の骨子を図を用い
て説明する。第３図は光デイスクの接着前の状態
にある断面の一部を示したものである。すなわ
ち、あらかじめレーザー記録膜７を形成した透明
基板５の上に、二液非混合型接着剤の一方の成分
を塗布した層８を設け、その一方で、保護となる
透明基板６上には、二液混合型接着剤の他の一成
分を塗布した層９を設け、これら二つの透明基板
を貼り合わせ、室温もしくは70゜〜80℃程度で短
時間に硬化させる。このとき、二液非混合型の接
着剤としては、いわゆる第二世代のアクリル系接
着剤をさすが、これに限定するわけではなく、混
合後、室温もしくは70゜〜80℃で速やかに硬化す
るものであればエポキシ系やシリコン系でも本発
明に適用できる。また、接着剤層８，９の塗布は
スクリーン印刷、回転塗布（スピンコート）、ロ
ールコート、スプレー、キスコートなど、接着剤
の性状に応じて適当な方式を採用してよい。接着
剤塗布時の記録膜の損傷をなくすため、記録膜７
と接着剤層８との間に、薄い保護膜を形成しても
よく、この場合の保護膜形成には、回転塗布が適
している。光デイスクは、透明基板の記録膜を形
成していない側から、集光されたレーザー光によ
り記録膜を変化させ、変化した部分と未変化部分
とのレーザー光の反射率の差によつて読み取りを
行なうというものであるため、記録膜近傍の接着
剤中に気泡が存在すると反射率が変化し、読み取
りのエラーを生じる場合がある。接着剤中への気
泡の混入を防止するためには、貼り合わせ工程を
減圧下で行なうことが適切である。
第４図に減圧貼り合わせ工程の状態図を示す。
すなわち、真空容器１０の中に、上下に動く軸１
３，１４に連結した台１１，１２を設け、この上
に、すでに接着剤８，９を塗布した透明基板１
１，１２を取り付け、ポンプ１５によつて真空容
器１０の内部を減圧にし、この状態で軸１３，１
４を動かし、貼り合わせるというものである。接
着剤の硬化は、減圧状態で行なつても、常圧下に
戻して硬化してもよく、この方法により、気泡の
ない高信頼性の接着状態が得られた。尚、このと
きの減圧度は、約20Torr以下が適当であり、こ
れ以上では気泡が混入することもある。
実施例 １
第３図に示したごとき断面状態になる光デイス
クの製造に当り、あらかじめ光記録膜７を形成し
た直径20cmの透明アクリル基板上に、スピンコー
トにより市販の二液非混合型アクリル系接着剤の
一成分を10μｍ厚に形成して接着剤層８を形成
し、一方で、保護となる透明アクリル基板６上
に、二液非混合型アクリル系接着剤層９を同じく
スピンコート法により10μｍ厚に形成した。これ
らの基板５，６を中心軸を揃えて平行に対向さ
せ、第４図に示した真空密着装置中にて貼り合わ
せ、室温下で５分間放置して硬化させた。真空密
着装置から取り出して後、一日静置して完全に硬
化させた。このようにして完成した光デイスクに
ついて以下に示す試験により評価した。
(1) 60℃−90％RH中200時間放置後、２日間室
中に放置し、接着剤のハクリを目視で調べる。
（湿度ハクリ試験）
(2) 第５図は、接着後の完成デイスク１０の断面
を示すが、接着完了後に基板がどの程度ソリ
ΔDを生じているかを、光学的に測定する。
（ソリ測定）評価結果を表に示す。
実施例 ２
断面の構造を第６図に示すごとく、あらかじめ
光記録膜１９を形成した直径20cmのアクリル基板
１１上に記録膜の保護膜２０をスピンコートによ
り2μｍ形成した。この保護膜とに、紫外線硬化
型アクリル系樹脂を用い、2μｍに塗布後、紫外
線硬化を行なつた。このようにして保護膜２０を
形成した基板上に、二液非混合型アクリル接着剤
の一成分をスクリーン印刷により厚さ30μｍに塗
布し接着層２１とした。他の一方の接着剤成分を
保護用のアクリル基板上に同じくスクリーン印刷
により30μｍ厚に塗布して接着層２２とした後、
２枚のアクリル基板を真空密着装置中にて貼り合
わせ、減圧を解除して常圧下にて、一日放置して
完全硬化した。このようにして作成した光デイス
クの湿中ハクリ性と、初期ソリ量を表に示す。
（比較例）
第２図に示すようにあらかじめ光記録膜３を形
成した直後20cmのアクリル基板上に、ウレタン系
の融点約80℃のホツトメルト接着剤を塗布し、他
方のアクリル基板２と熱プレスにより100℃に熱
圧着した。このようにして完成したデイスクの湿
中ハクリ性と初期ソリ量を表に示す。
INDUSTRIAL APPLICATION FIELD The present invention relates to an optical disk for laser recording and a method for adhering the same. Conventional structure and problems Laser recording disks (hereinafter referred to as optical disks) are large-capacity memory media that can store more than 10,000 A4 documents on a disk with a diameter of less than 30 cm. One bit corresponds to a small pit with a length of only around 1 μm. Also,
Information is written and read at a rate of 1000 per minute.
On a disk that is rotating at high speed than rotation, the diameter
It is executed by focusing a laser beam narrowed down to around 1 μm, detecting the position, and adjusting the focus.Even the slightest warpage of the board, deviation in parallelism, deformation, scratches, foreign objects, etc., can cause signal errors. It leads to For this reason, in the production of optical disks,
This requires the same level of care and attention as when manufacturing semiconductors. Conventionally, for the purpose of increasing reliability, an optical disk has a structure in which a laser recording thin film 3 is sandwiched between two transparent substrates 1 and 2, as shown in FIG. (However, FIG. 1 is a perspective view of an optical disk cut away, and hereinafter, a part A of the cross section will be enlarged to explain the laminated state. FIG. 2 shows an example of a single-sided recording optical disk. ) Therefore, the bonding process of bonding these two transparent substrates 1 and 2 together via the adhesive layer 4 is important, and this process often affects the yield and the reliability of the optical disk. Conventionally, a method using hot melt adhesive is known as this adhesive method, but this method
Because heat and pressure are applied at the same time, the substrate is prone to warping, distortion, scratches, and air bubbles.Furthermore, some recording films may also undergo deterioration due to the effects of heat.In addition, under high humidity conditions, It had many problems, including peeling due to a decrease in adhesive strength. Purpose of the Invention The present invention solves the above-mentioned drawbacks of conventional bonding methods, and enables the process of bonding optical discs, which requires high performance, to be carried out efficiently in a short time, and which also requires high temperatures during the process. Our objective is to provide an excellent adhesive method for optical discs that does not affect the recording film and provides strong adhesive strength that will not cause peeling even when left in high humidity for a long time. There is. Structure of the Invention The optical disk adhesion method of the present invention is based on the method of adhering a two-component non-mixable adhesive onto the surface of each substrate to be bonded in an optical disk plate having a structure in which two plastic transparent substrates are bonded together. After applying the previous two components separately and overlapping the adhesive coatings,
The purpose of this is to achieve the above-mentioned purpose. DESCRIPTION OF EMBODIMENTS Before describing specific examples, the gist of the present invention will be explained using figures. FIG. 3 shows a part of the cross section of the optical disk before it is bonded. That is, on a transparent substrate 5 on which a laser recording film 7 has been formed in advance, a layer 8 coated with one component of a two-component non-mixable adhesive is provided, and on the other hand, on the transparent substrate 6 serving as a protection, A layer 9 coated with another component of the two-component adhesive is provided, and these two transparent substrates are bonded together and cured in a short time at room temperature or about 70° to 80°C. At this time, the two-component non-mixable adhesive refers to the so-called second generation acrylic adhesive, but is not limited to this, and it is one that quickly hardens at room temperature or 70° to 80°C after mixing. If so, epoxy-based or silicon-based materials can also be applied to the present invention. Furthermore, the adhesive layers 8 and 9 may be applied by any suitable method depending on the properties of the adhesive, such as screen printing, spin coating, roll coating, spray coating, or kiss coating. In order to prevent damage to the recording film during adhesive application, the recording film 7
A thin protective film may be formed between the adhesive layer 8 and the adhesive layer 8, and spin coating is suitable for forming the protective film in this case. Optical discs change the recording film using focused laser light from the side of the transparent substrate that does not have a recording film formed on it, and read data based on the difference in reflectance of the laser light between the changed area and the unchanged area. Therefore, if air bubbles are present in the adhesive near the recording film, the reflectance may change and reading errors may occur. In order to prevent air bubbles from entering the adhesive, it is appropriate to carry out the bonding process under reduced pressure. FIG. 4 shows a state diagram of the vacuum bonding process.
That is, in the vacuum container 10, there is a shaft 1 that moves up and down.
3 and 14 are provided, and a transparent substrate 1 on which adhesives 8 and 9 have already been applied is provided.
1 and 12 are attached, the inside of the vacuum container 10 is reduced in pressure by the pump 15, and in this state, the shafts 13 and 1 are attached.
4 and paste them together. The adhesive may be cured under reduced pressure or may be cured under normal pressure. By this method, a highly reliable adhesive state free of bubbles was obtained. Note that the degree of pressure reduction at this time is preferably about 20 Torr or less; if it is more than this, bubbles may be mixed in. Example 1 In manufacturing an optical disk having a cross-sectional state as shown in FIG. 3, a commercially available two-component non-mixable acrylic material was spin-coated onto a transparent acrylic substrate with a diameter of 20 cm on which an optical recording film 7 was previously formed. An adhesive layer 8 is formed by forming one component of the adhesive to a thickness of 10 μm, and on the other hand, a two-component non-mixable acrylic adhesive layer 9 is formed on the protective transparent acrylic substrate 6 by the same spin coating method. It was formed to have a thickness of 10 μm. These substrates 5 and 6 were placed parallel to each other with their central axes aligned, and bonded together in a vacuum bonding apparatus shown in FIG. 4, and left at room temperature for 5 minutes to harden. After taking it out from the vacuum sealing device, it was left to stand for one day to be completely cured. The optical disc thus completed was evaluated by the tests shown below. (1) After being left for 200 hours at 60°C and 90%RH, leave it in a room for 2 days and visually check for peeling of the adhesive.
(Humidity Peeling Test) (2) FIG. 5 shows a cross section of the completed disk 10 after adhesion, and the extent to which the substrate warps ΔD after completion of adhesion is optically measured.
(Warp measurement) The evaluation results are shown in the table. Example 2 As shown in the cross-sectional structure of FIG. 6, a protective film 20 of 2 μm for a recording film was formed by spin coating on an acrylic substrate 11 with a diameter of 20 cm on which an optical recording film 19 had been previously formed. For this protective film, an ultraviolet curing type acrylic resin was used, and after coating to a thickness of 2 μm, ultraviolet curing was performed. On the substrate on which the protective film 20 was formed in this manner, one component of a two-component non-mixable acrylic adhesive was applied to a thickness of 30 μm by screen printing to form an adhesive layer 21. After applying the other adhesive component to a thickness of 30 μm on the protective acrylic substrate by screen printing to form the adhesive layer 22,
Two acrylic substrates were bonded together in a vacuum bonding device, the reduced pressure was released, and the bonding was left for one day under normal pressure to completely cure. The table below shows the peelability in humidity and the amount of initial warpage of the optical disks produced in this way. (Comparative example) As shown in Fig. 2, immediately after forming the optical recording film 3 in advance, a urethane-based hot melt adhesive with a melting point of about 80°C is applied onto a 20 cm acrylic substrate, and the other acrylic substrate 2 is hot-pressed. It was thermocompressed at 100℃. The table shows the wet peelability and initial amount of warpage of the disk thus completed.
【表】
表より、本発明の製造法により形成された光デ
イスクは初期ソリ量も少なく、湿中に長時間置い
てもハクリしないという性能を示した。
発明の効果
以上述べてきたように、本発明は信頼性が高
く、接着力が強い光デイスクの接着法に関するも
ので、比較的簡単な装置で、短時間に貼り合わせ
できるという優れた特徴を有する。[Table] From the table, the optical disk formed by the manufacturing method of the present invention had a small amount of initial warpage and exhibited performance that it did not peel off even when left in humidity for a long time. Effects of the Invention As described above, the present invention relates to a method for adhering optical disks that is highly reliable and has strong adhesive strength, and has the excellent feature that it can be bonded in a short time using a relatively simple device. .
第１図は完成光デイスクを切断した斜視図、第
２図、第３図、第６図は切断面の一部の拡大図、
第４図は減圧接着装置の断面構造を示す図、第５
図はデイスクのソリを説明した断面図を示す。
１，２，５，６，１７，１８……透明基板、
３，７，１９……光記録膜、４，８，９，２１，
２２……接着剤層、１０……真空槽、１１……下
部台座、１２……上部台座、１３，１４……上下
軸、１５……真空ライン、１６……貼り合わせデ
イスク、２０……保護膜。
Fig. 1 is a perspective view of a completed optical disk cut away; Figs. 2, 3, and 6 are enlarged views of a portion of the cut surface;
Figure 4 is a diagram showing the cross-sectional structure of the reduced pressure bonding device, Figure 5
The figure shows a cross-sectional view illustrating the warp of the disk. 1, 2, 5, 6, 17, 18...transparent substrate,
3, 7, 19... optical recording film, 4, 8, 9, 21,
22... Adhesive layer, 10... Vacuum chamber, 11... Lower pedestal, 12... Upper pedestal, 13, 14... Vertical axis, 15... Vacuum line, 16... Bonded disk, 20... Protection film.
Claims (1)
と他のプラスチツク製透明基板とを二液非混合型
接着剤で接合した断面構造を有する光デイスク。 ２ ２枚のプラスチツク製透明基板を貼り合わせ
る構成の光デイスク基板のそれぞれの基板の貼り
合わせようとする面上に、二液非混合型接着剤の
混合前の２成分を別々に塗り分け、接着剤塗布同
志を減圧下で重ね合わせて後、硬化してなる光デ
イスクの接着法方。[Scope of Claims] 1. An optical disk having a cross-sectional structure in which a plastic transparent substrate on which an optical recording film is formed and another plastic transparent substrate are bonded together using a two-component non-mixable adhesive. 2. Apply the two components of the two-component non-mixable adhesive separately on the surface of each of the optical disk substrates to be bonded together in a structure in which two plastic transparent substrates are bonded together. A method of adhering optical discs that is made by overlapping adhesive-coated materials under reduced pressure and then curing them.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59171906A JPS6150231A (en) | 1984-08-18 | 1984-08-18 | Optical disc and its bonding method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59171906A JPS6150231A (en) | 1984-08-18 | 1984-08-18 | Optical disc and its bonding method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6150231A JPS6150231A (en) | 1986-03-12 |
| JPH0443332B2 true JPH0443332B2 (en) | 1992-07-16 |
Family
ID=15932015
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59171906A Granted JPS6150231A (en) | 1984-08-18 | 1984-08-18 | Optical disc and its bonding method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6150231A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2826728B2 (en) * | 1986-10-31 | 1998-11-18 | セイコーエプソン株式会社 | Manufacturing method of optical recording medium |
| JPH02208841A (en) * | 1989-02-07 | 1990-08-20 | Japan Steel Works Ltd:The | Method and device for production of optical disk |
| US5244775A (en) | 1991-03-20 | 1993-09-14 | Hitachi, Ltd. | Method of manufacturing an optical disc |
| JPH06131705A (en) * | 1992-10-16 | 1994-05-13 | Hitachi Ltd | Device for adhering optical disk |
| JP2003085837A (en) * | 2001-09-13 | 2003-03-20 | Tdk Corp | Method of manufacturing optical recording medium and optical recording medium |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5965950A (en) * | 1982-10-05 | 1984-04-14 | Canon Inc | Optical recording element |
-
1984
- 1984-08-18 JP JP59171906A patent/JPS6150231A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5965950A (en) * | 1982-10-05 | 1984-04-14 | Canon Inc | Optical recording element |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6150231A (en) | 1986-03-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4158409B2 (en) | Manufacturing method of optical disc | |
| JPH01217738A (en) | Optical disk | |
| JPH11238255A (en) | Optical disk | |
| JPH0443332B2 (en) | ||
| JPS6150232A (en) | Optical recording medium and its manufacture | |
| JPS61267947A (en) | Optical disk | |
| JP2002170284A (en) | Optical information carrier and its manufacturing method | |
| JPH0370296B2 (en) | ||
| JPH0750035A (en) | Method and apparatus for manufacture of optical disc | |
| JPS61151853A (en) | Optical disk | |
| JPH05151625A (en) | Production of optical disk | |
| JPS6166239A (en) | Optical disk | |
| JPS61182646A (en) | Optical disk and its production | |
| JPH0969239A (en) | Optical disk and its manufacture | |
| JPS6173251A (en) | Manufacture of optical disk | |
| JPH0227538A (en) | Both-face optical disk | |
| JPS613340A (en) | Adhering method of optical disk | |
| JP2519997B2 (en) | Optical recording medium | |
| JPH04344344A (en) | Tight sticking type optical information recording medium | |
| JPS6387631A (en) | Production of optical disk | |
| JP2721655B2 (en) | Composite optical disk structure | |
| JPH11213467A (en) | Lamination type optical information recording medium manufacturing method and double coated adhesive sheet | |
| JPH11328755A (en) | Production of information recording medium | |
| JPS621142A (en) | Optical disk | |
| JPS6180630A (en) | Reflected light disc and its manufacture |