JP2001134981A - Multilayered optical disk - Google Patents
Multilayered optical diskInfo
- Publication number
- JP2001134981A JP2001134981A JP31399499A JP31399499A JP2001134981A JP 2001134981 A JP2001134981 A JP 2001134981A JP 31399499 A JP31399499 A JP 31399499A JP 31399499 A JP31399499 A JP 31399499A JP 2001134981 A JP2001134981 A JP 2001134981A
- Authority
- JP
- Japan
- Prior art keywords
- signal recording
- recording layer
- signal
- reflection film
- selective reflection
- 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.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、信号記録層を複数
有する多層光ディスクに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer optical disk having a plurality of signal recording layers.
【０００２】[0002]
【従来の技術】光ディスクの記録面にピットを配列し、
このピットの寸法を記録情報に応じて変調させることに
よりデジタルオーディオ信号やビデオ信号を再生できる
ようにした光ディスク（ＣＤ等）が広く普及している。
また、ＣＤと同じようにピット列で信号を記録し、片面
で４．７Ｇｂｙｔｅｓ、両面で８．５Ｇｂｙｔｅｓの記
録容量を有する高密度の再生専用の光ディスクであるＤ
ＶＤも発売されるに到っている。2. Description of the Related Art Pits are arranged on a recording surface of an optical disk,
Optical discs (CDs and the like) that can reproduce digital audio signals and video signals by modulating the dimensions of the pits in accordance with recording information have become widespread.
Similarly to a CD, a high-density read-only optical disk which records signals in a pit row and has a recording capacity of 4.7 Gbytes on one side and 8.5 Gbytes on both sides.
VD has also been released.
【０００３】また更に、ＤＶＤと同じ記録容量を持ち、
記録可能な光ディスクとしてＤＶＤ−ＲＡＭも開発され
ている。また、ＤＶＤより高い記録容量を実現するため
に、信号記録面を２以上形成した多層式光ディスクも開
発されている。Further, it has the same recording capacity as a DVD,
A DVD-RAM has also been developed as a recordable optical disk. Further, in order to realize a recording capacity higher than that of a DVD, a multilayer optical disc having two or more signal recording surfaces has been developed.
【０００４】[0004]
【発明が解決しようとする課題】しかし、従来の多層光
ディスクでは、次のような問題がある。即ち、図７を参
照して、従来の多層光ディスク３０は、透光性基板７０
の一主面に第１の信号記録層７１、第２の信号記録層７
２、第３の信号記録層７３、および第４の信号記録層７
４を順次形成し、第４の信号記録層７４を覆うように保
護層７５を形成した断面構造を有する。そして、第１の
信号記録層７１、第２の信号記録層７２、第３の信号記
録層７３、および第４の信号記録層７４は、ＡｌやＡｕ
等の反射率の高い金属から成る反射層を含むため、入斜
面７６からレーザ光ＬＢを入斜し、第２の信号記録層７
２の信号を再生しようとした場合、第２の信号記録層７
２でのみレーザ光が反射されるのではなく、第１の信号
記録層７１によってもレーザ光が反射され、反射成分Ｌ
ＢＨ１が光検出器により検出される。その結果、再生信
号にクロストークが発生するという問題が生じる。However, the conventional multilayer optical disk has the following problems. That is, referring to FIG. 7, the conventional multilayer optical disc 30 is
The first signal recording layer 71 and the second signal recording layer 7
2, third signal recording layer 73, and fourth signal recording layer 7
4 are formed sequentially, and a protection layer 75 is formed so as to cover the fourth signal recording layer 74. The first signal recording layer 71, the second signal recording layer 72, the third signal recording layer 73, and the fourth signal recording layer 74 are made of Al or Au.
And so on, the laser beam LB is obliquely incident from the oblique surface 76 and the second signal recording layer 7.
2 is to be reproduced, the second signal recording layer 7
2, the laser light is reflected not only by the first signal recording layer 71 but also by the first signal recording layer 71, and the reflected component L
BH1 is detected by the photodetector. As a result, there is a problem that crosstalk occurs in the reproduced signal.
【０００５】このクロストークの問題は、各信号記録面
層の距離を小さくした場合に生じ易いが、クロストーク
を低減するために各信号記録層間の距離を大きくする
と、レーザ光を集光する対物レンズの設計値とのずれが
大きくなり、集光したレーザ光に収差が発生という問題
がある。また、各信号記録層から信号を再生するには、
各信号記録層において、ある程度の反射率が必要である
が、各信号記録層の反射率を大きくすると、レーザ光の
入射側から最も奥側に存在する信号記録層から信号を再
生する場合、手前の信号記録層でもレーザ光が反射して
しまい、本来、信号を再生しようとする信号記録層での
反射率が実質的に小さくなるので、奥側に存在する信号
記録層から信号を再生することが困難であるという問題
がある。The problem of crosstalk is likely to occur when the distance between the signal recording layers is reduced. However, when the distance between the signal recording layers is increased to reduce the crosstalk, the object for condensing the laser light is reduced. There is a problem that the deviation from the design value of the lens becomes large, and aberration occurs in the focused laser light. To reproduce signals from each signal recording layer,
In each signal recording layer, a certain degree of reflectivity is required. However, if the reflectivity of each signal recording layer is increased, when a signal is reproduced from the signal recording layer located farthest from the incident side of the laser beam, the front side Since the laser light is also reflected on the signal recording layer of the first layer and the reflectivity of the signal recording layer from which the signal is originally to be reproduced is substantially reduced, it is necessary to reproduce the signal from the signal recording layer located on the back side. There is a problem that is difficult.
【０００６】一方、各信号信号記録層に波長依存性を有
する反射膜を用いるアイデアもあるが、この方法では、
信号記録層の数と同じ数の半導体レーザが必要になると
いう問題がある。そこで、本願発明は、かかる問題を解
決し、１つの半導体レーザを使用して各信号記録層から
のクロストークを低減した信号再生が可能な多層光ディ
スクを提供することを目的とする。On the other hand, there is an idea to use a reflective film having wavelength dependency for each signal signal recording layer.
There is a problem that the same number of semiconductor lasers as the number of signal recording layers are required. Accordingly, an object of the present invention is to solve the above problem and to provide a multilayer optical disc capable of reproducing signals with reduced crosstalk from each signal recording layer using one semiconductor laser.
【０００７】[0007]
【課題を解決するための手段および発明の効果】請求項
１に係る発明は、ｍ個の信号記録層を有し、ｍ個の信号
記録層の各々が、信号を記録したピット列と、ピット列
を覆うように形成された室温で透明膜であり、所定の温
度以上で反射膜に変化する選択反射膜とから成る多層光
ディスクである。The invention according to claim 1 has m signal recording layers, and each of the m signal recording layers has a pit row in which a signal is recorded and a pit row. This is a multilayer optical disc comprising a transparent film at room temperature formed to cover the rows and a selective reflection film that changes to a reflection film at a predetermined temperature or higher.
【０００８】請求項１に記載された多層光ディスクにお
いては、ｍ個の信号記録層のうち、信号を再生しようと
する信号記録層にレーザ光が集光照射されると、その信
号記録層を構成する選択反射膜のうちレーザ光が集光照
射された領域だけが温度上昇し、反射膜に変化する。一
方、信号を再生しようとする信号記録層以外の信号記録
層にはレーザ光が集光されないので、その信号記録層を
構成する選択反射膜の温度は上昇せず、透明を保持した
ままである。従って、レーザ光は、信号を再生しようと
する信号記録層において、温度が上昇した領域のみで反
射され、信号を再生しようとする信号記録層以外の信号
記録層をそのまま透過して光検出器により検出される。
そして、レーザ光が移動してレーザ光を集光照射した領
域の温度が下がると、反射膜から透明膜に変化する。In the multi-layer optical disc according to the first aspect, when a laser beam is focused and irradiated on a signal recording layer from which signals are to be reproduced out of the m signal recording layers, the signal recording layer is formed. Only the region of the selective reflection film to which the laser light is focused and irradiated rises in temperature and changes to a reflection film. On the other hand, since laser light is not focused on a signal recording layer other than the signal recording layer from which a signal is to be reproduced, the temperature of the selective reflection film constituting the signal recording layer does not rise and remains transparent. . Therefore, the laser light is reflected only in the region where the temperature has risen in the signal recording layer from which the signal is to be reproduced, and passes through the signal recording layer other than the signal recording layer from which the signal is to be reproduced as it is, and is reflected by the photodetector. Is detected.
Then, when the laser light moves and the temperature of the region where the laser light is condensed and irradiated falls, the reflection film changes to a transparent film.
【０００９】従って、請求項１に記載された発明によれ
ば、信号を再生しようとする信号記録層以外の信号記録
層からのクロストークを除去して各信号記録層から信号
を再生できる。また、請求項２に係る発明は、ｍ個の信
号記録面を有し、レーザ光の入射側からｍ−１番目まで
の信号記録層の各々が、信号を記録したピット列と、ピ
ット列を覆うように形成された室温で透明膜であり、所
定の温度以上で反射膜に変化する選択反射膜とから成
り、レーザ光の入射側からｍ番目の信号記録層が、信号
を記録したピット列と、ピット列を覆うように形成され
た反射膜とから成る多層光ディスクである。Therefore, according to the first aspect of the invention, signals can be reproduced from each signal recording layer by removing crosstalk from the signal recording layers other than the signal recording layer from which the signal is to be reproduced. Further, the invention according to claim 2 has m signal recording surfaces, and each of the (m-1) th signal recording layers from the laser beam incident side includes a pit row in which a signal is recorded and a pit row. A m-th signal recording layer from the laser light incident side, which is a pit train on which a signal is recorded, which is a transparent film formed at room temperature, which is a transparent film at room temperature, and which changes into a reflective film at a predetermined temperature or higher. And a reflective film formed so as to cover the pit row.
【００１０】請求項２に記載された多層光ディスクにお
いては、レーザ光の入射側からｍ番目までの信号記録層
のうち、信号を再生しようとする信号記録層にレーザ光
が集光照射されると、その信号記録層を構成する選択反
射膜のうちレーザ光が集光照射された領域だけが温度上
昇し、反射膜に変化する。一方、信号を再生しようとす
る信号記録層以外の信号記録層にはレーザ光が集光され
ないので、その信号記録層を構成する選択反射膜の温度
は上昇せず、透明を保持したままである。従って、レー
ザ光は、信号を再生しようとする信号記録層において、
温度が上昇した領域のみで反射され、信号を再生しよう
とする信号記録層以外の信号記録層をそのまま透過して
光検出器により検出される。そして、レーザ光が移動し
てレーザ光を集光照射した領域の温度が下がると、反射
膜から透明膜に変化する。In the multi-layer optical disc according to the present invention, when the laser beam is focused and irradiated on the signal recording layer from which the signal is to be reproduced, of the m-th signal recording layer from the laser beam incident side. Only the area of the selective reflection film constituting the signal recording layer, on which the laser beam is condensed and irradiated, rises in temperature and changes to a reflection film. On the other hand, since laser light is not focused on a signal recording layer other than the signal recording layer from which a signal is to be reproduced, the temperature of the selective reflection film constituting the signal recording layer does not rise and remains transparent. . Therefore, the laser light is applied to the signal recording layer where the signal is to be reproduced.
The light is reflected only in the region where the temperature has risen, passes through the signal recording layer other than the signal recording layer from which the signal is to be reproduced, and is detected by the photodetector. Then, when the laser light moves and the temperature of the region where the laser light is condensed and irradiated falls, the reflection film changes to a transparent film.
【００１１】また、レーザ光の入射側からｍ番目の信号
記録層、即ち、最も奥に存在する信号記録層は、レーザ
光の照射の有無に無関係に反射膜であるので、その信号
記録層に照射されたレーザ光は反射膜で反射され、他の
ｍ−１個の信号記録層をそのまま透過して光検出器で検
出される。従って、請求項２に記載された発明によれ
ば、信号を再生しようとする信号記録層以外の信号記録
層からのクロストークを除去して各信号記録層から信号
を再生できる。The m-th signal recording layer from the laser beam incident side, that is, the signal recording layer located at the innermost position is a reflection film regardless of whether or not the laser beam is irradiated. The irradiated laser light is reflected by the reflection film, passes through the other m-1 signal recording layers as it is, and is detected by the photodetector. Therefore, according to the second aspect of the invention, signals can be reproduced from each signal recording layer by removing crosstalk from the signal recording layers other than the signal recording layer from which the signal is to be reproduced.
【００１２】また、請求項３に係る発明は、請求項１ま
たは請求項２に記載の多層光ディスクにおいて、選択反
射膜は、Ａｇ2Ｏから成る多層光ディスクである。請求
項３に記載された多層光ディスクにおいては、選択反射
膜はスパッタリング法により形成される。従って、請求
項３に記載された発明によれば、信号を再生しようとす
る信号記録層以外の信号記録層からのクロストークを除
去して各信号記録層から信号を再生できる多層光ディス
クを容易に作製できる。According to a third aspect of the present invention, there is provided the multilayer optical disk according to the first or second aspect, wherein the selective reflection film is made of Ag 2 O. In the multilayer optical disk according to the third aspect, the selective reflection film is formed by a sputtering method. Therefore, according to the third aspect of the present invention, it is possible to easily provide a multi-layer optical disc capable of reproducing signals from each signal recording layer by removing crosstalk from signal recording layers other than the signal recording layer from which signals are to be reproduced. Can be made.
【００１３】[0013]
【発明の実施の形態】本発明の実施の形態を図を参照し
つつ説明する。図１を参照して、本願発明に係る多層光
ディスク１０は、透光性基板１と、第１の信号記録層２
と、第２の信号記録層３と、第３の信号記録層４と、第
４の信号記録層５と、第１の信号記録層２と第２の信号
記録層３との間、第２の信号記録層３と第３の信号記録
層４との間、および第３の信号記録層４と第４の信号記
録層５との間に形成された樹脂６と、保護層７とを備え
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, a multilayer optical disc 10 according to the present invention includes a light-transmitting substrate 1 and a first signal recording layer 2.
, The second signal recording layer 3, the third signal recording layer 4, the fourth signal recording layer 5, the first signal recording layer 2 and the second signal recording layer 3, A resin 6 formed between the third signal recording layer 3 and the third signal recording layer 4 and between the third signal recording layer 4 and the fourth signal recording layer 5, and a protective layer 7. .
【００１４】第１の信号記録層２は、信号を記録したピ
ット２１列と、ピット２１列を覆うように形成された選
択反射膜２２とから成り、第２の信号記録層３は、信号
を記録したピット３１列と、ピット３１列を覆うように
形成された選択反射膜３２とから成り、第３の信号記録
層４は、信号を記録したピット４１列と、ピット４１列
を覆うように形成された選択反射膜４２とから成り、第
４の信号記録層５は、信号を記録したピット５１列と、
ピット５１列を覆うように形成された反射膜５２とから
成る。即ち、レーザ光の入射面８から最も遠い位置に存
在する第４の信号記録層５のみがレーザ光の照射の有無
に無関係に一定の反射率を有する反射膜を含む信号記録
層である。また、選択反射膜２２、３２、４２は、室温
では透明であり、レーザ光が照射されて温度が上昇とす
ると反射膜になるものである。The first signal recording layer 2 includes a row of pits 21 on which signals are recorded, and a selective reflection film 22 formed so as to cover the row of pits 21. The third signal recording layer 4 is composed of 31 rows of recorded pits and a selective reflection film 32 formed so as to cover the 31 rows of pits. The fourth signal recording layer 5 includes a row of pits 51 on which signals are recorded,
And a reflective film 52 formed so as to cover the rows of pits 51. That is, only the fourth signal recording layer 5 located farthest from the laser light incident surface 8 is a signal recording layer including a reflective film having a constant reflectance regardless of whether or not the laser light is irradiated. The selective reflection films 22, 32, and 42 are transparent at room temperature, and become reflection films when the temperature is increased by irradiation with laser light.
【００１５】また、透光性基板１は、ガラス、ポリカー
ボネート等から成り、選択反射膜２２、３２、４２、５
２は、Ａｇ2Ｏから成り、樹脂６は、紫外線硬化樹脂か
ら成り、保護層７もポリカーボネートまたは紫外線硬化
樹脂から成る。選択反射膜２２、３２、４２、５２を構
成するＡｇ2Ｏは、室温で暗褐色または褐黒色をした半
透明膜である。そして、Ａｇ2Ｏは、熱および光に対し
て不安定であり、１６０度以上の温度で次の化学式によ
り分解が起こる。The light-transmitting substrate 1 is made of glass, polycarbonate, or the like, and selectively reflects films 22, 32, 42, 5,
2 is made of Ag 2 O, the resin 6 is made of an ultraviolet curable resin, and the protective layer 7 is also made of polycarbonate or an ultraviolet curable resin. Ag 2 O constituting the selective reflection films 22, 32, 42, and 52 is a translucent film having a dark brown or brown-black color at room temperature. Ag 2 O is unstable to heat and light, and decomposes at a temperature of 160 ° C. or more by the following chemical formula.
【００１６】 ２Ａｇ2Ｏ→４Ａｇ＋Ｏ2・・・・・・・・・・（１） 上記（１）式の化学式は可逆式であるので、温度が下が
るとＡｇ2Ｏに戻る。従って、レーザ光をＡｇ2Ｏに集光
照射することによりＡｇ2Ｏの温度が１６０度以上に上
昇すると上記（１）式のように銀（Ａｇ）に変化するた
め、反射率が大きくなる。2Ag 2 O → 4Ag + O 2 (1) Since the chemical formula of the above formula (1) is a reversible formula, it returns to Ag 2 O when the temperature decreases. Therefore, when the temperature of Ag 2 O rises to 160 ° C. or more by converging and irradiating the laser beam on Ag 2 O, the reflectivity changes to silver (Ag) as shown in the above equation (1), thereby increasing the reflectance.
【００１７】Ａｇ2Ｏは室温で半透明膜であるが、一般
にＤＶＤ等の光ディスクの信号再生に用いられている波
長６３５ｎｍのレーザ光に対する透過率を計算すると、
次のようになる。吸収係数α（１０-2／ｎｍ）、膜厚ｄ
（１０2ｎｍ）の物質の透過率Ｔは一般に次式で表され
る。 Ｔ＝ｅｘｐ（−αｄ）・・・・・・・・・・・（２） また、吸収係数αは、吸収率ｋ、波長λを用いて次式で
表される。Ag 2 O is a translucent film at room temperature. When the transmittance of a laser beam having a wavelength of 635 nm, which is generally used for signal reproduction of an optical disk such as a DVD, is calculated,
It looks like this: Absorption coefficient α (10 -2 / nm), film thickness d
The transmittance T of a (10 2 nm) substance is generally represented by the following equation. T = exp (−αd) (2) The absorption coefficient α is expressed by the following equation using the absorption rate k and the wavelength λ.
【００１８】 α＝４πｋ／λ・・・・・・・・・・・・・・（３） Ａｇ2Ｏの吸収率ｋは０．１であるので、吸収係数αは
次式のようになる。 α＝４πｋ／λ＝４π×０．１／６３５＝０．１９８（１０-2／ｎｍ） ・・・・・・・・・・・・・・・・・・・（４） また、膜厚ｄを０．５×１０2ｎｍとすると、透過率Ｔ
は次式のようになる。Α = 4πk / λ (3) Since the absorption coefficient k of Ag 2 O is 0.1, the absorption coefficient α is as follows: . α = 4πk / λ = 4π × 0.1 / 635 = 0.198 (10 −2 / nm) (4) The film thickness When d is 0.5 × 10 2 nm, the transmittance T
Becomes as follows.
【００１９】 Ｔ＝ｅｘｐ（−αｄ）＝ｅｘｐ（−０．１９８×０．５）＝０．９ ・・・・・・・・・・・・・・・・・・・・（５） 従って、膜厚５０ｎｍのＡｇ2Ｏの透過率は約９０％と
なり、室温においては透明膜として十分に使用できる。
また、選択反射膜２２、３２、４２は、ＡｇＮＯ3で構
成されていても良いが、ＡｇＮＯ3は、室温で無色透明
の物質であり、４４４度に加熱すると、次の化学式によ
り分解が起こり、銀（Ａｇ）が生じる。T = exp (−αd) = exp (−0.198 × 0.5) = 0.9 (5) The transmittance of Ag 2 O having a thickness of 50 nm is about 90%, and it can be sufficiently used as a transparent film at room temperature.
Further, the selective reflection film 22, 32 and 42 may be constituted by AgNO 3 but, AgNO 3 is a colorless transparent material at room temperature, when heated to 444 degrees, occurs decomposed by the following formula, Silver (Ag) is produced.
【００２０】 ＡｇＮＯ3→Ａｇ＋ＮＯ2＋Ｏ・・・・・・・・（６） ＡｇＮＯ3はＡｇより安定であるため、室温ではＡｇＮ
Ｏ3に戻る。ＡｇＮＯ3は、室温で無色透明であるので、
波長６３５ｎｍのレーザ光に対する透過率は約１００％
と考えられる。従って、ＡｇＮＯ3も選択反射膜２２、
３２、４２として十分に使用できる。AgNO 3 → Ag + NO 2 + O (6) Since AgNO 3 is more stable than Ag, it is AgN at room temperature.
Back to O 3. Since AgNO 3 is colorless and transparent at room temperature,
About 100% transmittance for 635 nm wavelength laser light
it is conceivable that. Therefore, AgNO 3 is also used for the selective reflection film 22,
32 and 42 can be sufficiently used.
【００２１】反射膜として、膜厚５０ｎｍのＡｇ2Ｏを
用いて信号記録層を増加した場合、各信号記録層におけ
る反射率を図２に示す。この場合、膜厚５０ｎｍのＡｇ
2Ｏが膜厚５０ｎｍのＡｇに変化するとして計算した。
第２の信号記録層３の反射率は、第１の信号記録層２
（透過率：９０％）を２度通過することになるので、８
０％×（０．９）2＝６５％となる。図２の結果から信
号記録層を６層形成した場合、第６層目でも反射率が２
８％であり、信号を再生するには十分な反射率である。
ＡｇＮＯ3については、Ａｇ2Ｏより透過率が高いので、
５０ｎｍのＡｇＮＯ3を選択反射膜２２、３２、４２と
して用いても、各信号記録層の反射率は、図２に示す反
射率より大きくなるので、信号記録層の数を６層以上に
増加させることができる。When the number of signal recording layers is increased using Ag 2 O having a thickness of 50 nm as the reflection film, the reflectivity of each signal recording layer is shown in FIG. In this case, a 50 nm thick Ag
The calculation was performed on the assumption that 2 O changed to Ag having a thickness of 50 nm.
The reflectance of the second signal recording layer 3 is
(Transmittance: 90%) twice.
0% × (0.9) 2 = 65%. From the results of FIG. 2, when six signal recording layers are formed, the reflectance is 2 even at the sixth layer.
8%, which is a sufficient reflectance to reproduce a signal.
Since AgNO 3 has a higher transmittance than Ag 2 O,
Even if 50 nm of AgNO 3 is used as the selective reflection films 22, 32, and 42, the reflectance of each signal recording layer becomes larger than the reflectance shown in FIG. 2, so the number of signal recording layers is increased to six or more. be able to.
【００２２】また、透光性基板１の膜厚、即ち、レーザ
光の入射面８から第１の信号記録層２までの距離は、
０．６ｍｍ（許容誤差：±０．１ｍｍ）であり、第１の
信号記録層２と第２の信号記録層３との距離、第２の信
号記録層３と第３の信号記録層４との距離、および第３
の信号記録層４と第４の信号記録層５との距離は、１０
μｍ程度であり、保護層７の膜厚は、０．６ｍｍ（許容
誤差：±０．１ｍｍ）である。The thickness of the light-transmitting substrate 1, that is, the distance from the laser light incident surface 8 to the first signal recording layer 2 is:
0.6 mm (tolerance: ± 0.1 mm), the distance between the first signal recording layer 2 and the second signal recording layer 3, the distance between the second signal recording layer 3 and the third signal recording layer 4, The distance of the third
The distance between the signal recording layer 4 and the fourth signal recording layer 5 is 10
μm, and the thickness of the protective layer 7 is 0.6 mm (tolerance: ± 0.1 mm).
【００２３】図３を参照して、多層光ディスク１０に入
射面８からレーザ光ＬＢを照射し、第３の信号記録層４
から信号を再生しようとした場合、第３の信号記録層４
の手前に存在する第１の信号記録層２、および第２の信
号記録層３にはレーザ光が集光されないので、選択反射
膜２２、３２の温度は上昇せず、レーザ光ＬＢをそのま
ま透過する。そして、レーザ光ＬＢは第３の信号記録層
４に集光され、特定の領域４３のみが温度上昇して反射
膜になる。そして、第３の信号記録層４に集光照射され
たレーザ光は特定の領域４３でのみ反射されて、第２の
信号記録層３、第１の信号記録層２、および透光性基板
１をそのまま透過して光検出器（図示省略）で検出され
る。そして、レーザ光ＬＢが移動すると、特定の領域４
３の温度が下がり、透明膜となる。また、第４の信号記
録層５には、室温においてもレーザ光を反射する反射膜
５２が含まれているので、第４の信号記録層５では、温
度上昇に無関係にレーザ光を反射して信号が再生され
る。Referring to FIG. 3, a multilayer optical disc 10 is irradiated with a laser beam LB from an incident surface 8 to form a third signal recording layer 4.
To reproduce a signal from the third signal recording layer 4
The laser light is not condensed on the first signal recording layer 2 and the second signal recording layer 3 existing in front of the above, so that the temperatures of the selective reflection films 22 and 32 do not rise, and the laser light LB is directly transmitted. I do. Then, the laser beam LB is condensed on the third signal recording layer 4, and only the specific region 43 is heated and becomes a reflection film. Then, the laser light focused and irradiated on the third signal recording layer 4 is reflected only in a specific area 43, and the second signal recording layer 3, the first signal recording layer 2, and the light transmitting substrate 1 are reflected. Is transmitted as it is and detected by a photodetector (not shown). Then, when the laser beam LB moves, the specific area 4
The temperature of No. 3 decreases, and a transparent film is formed. Further, since the fourth signal recording layer 5 includes the reflection film 52 that reflects the laser beam even at room temperature, the fourth signal recording layer 5 reflects the laser beam regardless of the temperature rise. The signal is reproduced.
【００２４】従って、多層光ディスク１０においては、
各信号記録層２、３、４に含まれる選択反射膜２２、３
２、４２のうち、レーザ光ＬＢが集光照射された領域の
みが昇温されて反射膜に変化し、その領域のみから信号
を再生でき、他の信号記録層からのクロストークはな
い。図４を参照して、多層光ディスク１０に対して対物
レンズのフォーカスサーボの引き込みを開始した時のフ
ォーカスエラー信号について説明する。多層光ディスク
１０の第１の信号記録層２、第２の信号記録層３、およ
び第３の信号記録層４に、第４の信号記録層５に含まれ
る反射膜５２と同じ反射膜が含まれる場合には、点線で
示すＳ字カーブ１５、１６、１７と、実線で示すＳ字カ
ーブ１４とが検出される。しかし、第１の信号記録層
２、第２の信号記録層３、および第３の信号記録層４に
は、室温で透明膜であり、所定の温度以上で反射膜に変
化する選択反射膜２２、３２、４２が用いられているた
め、レーザ光ＬＢが照射され、選択反射膜２２、３２、
４２の温度が所定の温度以上に昇温されるまでは、第１
の信号記録層２、第２の信号記録層３、および第３の信
号記録層４からはフォーカスエラー信号が検出されず、
所定の温度以上に昇温されてからフォーカスエラー信号
が第１の信号記録層２、第２の信号記録層３、および第
３の信号記録層４から検出される。従って、第１の信号
記録層２、第２の信号記録層３、および第３の信号記録
層４からは、それぞれ、Ｚ字のフォーカスエラー信号１
１、１２、１３が検出される。そして、第４の信号記録
層５からは、通常のＳ字のフォーカスエラー信号１４が
検出される。Ｚ字のフォーカスエラー信号１１の点Ｐ
１、Ｚ字のフォーカスエラー信号１２の点Ｐ３、および
Ｚ字のフォーカスエラー信号１３の点Ｐ５は、それぞ
れ、選択反射膜２２、３２、４２が所定の温度に昇温さ
れた時点であり、Ｚ字のフォーカスエラー信号１１の点
Ｐ２、Ｚ字のフォーカスエラー信号１２の点Ｐ４、およ
びＺ字のフォーカスエラー信号１３の点Ｐ６は、それぞ
れ、選択反射膜２２、３２、４２が所定の温度以下に降
温される時点である。第１の信号記録層２、第２の信号
記録層３、および第３の信号記録層４に室温で透明膜で
あり、所定の温度以上で反射膜に変化する選択反射膜２
２、３２、４２を用いた場合にも、第１の信号記録層
２、第２の信号記録層３、および第３の信号記録層４か
ら、それぞれ、フォーカスエラー信号１１、１２、１３
が検出されるので、各信号記録層２、３、４、５へフォ
ーカスジャンプすることが可能である。Therefore, in the multilayer optical disc 10,
Selective reflection film 22, 3 included in each signal recording layer 2, 3, 4
Of the areas 2, 42, only the area irradiated with the laser beam LB is heated and changes to a reflective film, and signals can be reproduced only from that area, and there is no crosstalk from other signal recording layers. With reference to FIG. 4, a description will be given of a focus error signal when the focus servo of the objective lens is started for the multilayer optical disc 10. The first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4 of the multilayer optical disc 10 include the same reflection film as the reflection film 52 included in the fourth signal recording layer 5. In this case, S-shaped curves 15, 16, and 17 indicated by dotted lines and S-shaped curve 14 indicated by solid lines are detected. However, the first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4 are transparent films at room temperature and are selective reflection films 22 which change to reflection films at a predetermined temperature or higher. , 32, and 42 are used, so that the laser beam LB is irradiated, and the selective reflection films 22, 32, and
Until the temperature of 42 rises to a predetermined temperature or higher, the first
No focus error signal is detected from the signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4,
After the temperature is raised to a predetermined temperature or higher, a focus error signal is detected from the first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4. Accordingly, the first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4 respectively output a Z-shaped focus error signal 1 from the Z signal.
1, 12, and 13 are detected. Then, a normal S-shaped focus error signal 14 is detected from the fourth signal recording layer 5. Point P of Z-shaped focus error signal 11
1, a point P3 of the Z-shaped focus error signal 12 and a point P5 of the Z-shaped focus error signal 13 are points in time when the selective reflection films 22, 32, and 42 are heated to a predetermined temperature, respectively. The point P2 of the focus error signal 11 of the letter, the point P4 of the focus error signal 12 of the letter Z, and the point P6 of the focus error signal 13 of the letter Z have the selective reflection films 22, 32, and 42, respectively, below the predetermined temperature. This is the time when the temperature is lowered. The first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4 are transparent films at room temperature and are selective reflection films 2 which change into reflection films at a predetermined temperature or higher.
2, 32, and 42, the focus error signals 11, 12, 13 from the first signal recording layer 2, the second signal recording layer 3, and the third signal recording layer 4, respectively.
Is detected, it is possible to make a focus jump to each of the signal recording layers 2, 3, 4, and 5.
【００２５】図５、６を参照して、多層光ディスク１０
の作製について説明する。まず、スタンパ６０Ａの信号
が記録された面を樹脂６１で覆い（図５の（ａ））、樹
脂６１にガラスまたはポリカーボネート６２を接触させ
る（図５の（ｂ））。そして、ガラスまたはポリカーボ
ネート６２側から紫外線（図示省略）を照射して樹脂６
１を硬化させる。その後、信号記録面が形成された樹脂
６１とガラスまたはポリカーボネート６２とをスタンパ
６０Ａから取り外すと透光性基板１の一主面にピット２
１列が形成されたものが作製される。ここで、樹脂６１
とガラスまたはポリカーボネート６２とで透光性基板１
が構成される。そして、ピット２１列を覆うように選択
反射膜２２を形成すると、透光性基板１の一主面に第１
の信号記録層２が形成される（図５の（ｃ））。この場
合、選択反射膜２２としてＡｇ2Ｏ、ＡｇＮＯ3がスパッ
タリング法により約５０ｎｍ形成される。その後、スタ
ンパ６０Ａの信号記録面とは異なる信号記録面を有する
スタンパ６０Ｂの信号記録面を樹脂６３で覆い（図５の
（ｄ））、樹脂６３上に図５の（ｃ）の工程で作製した
透光性基板１の一主面に第１の信号記録層２を形成した
ものを接触させ（図５の（ｅ））、透光性基板１側から
紫外線（図示省略）を照射して樹脂６３を硬化させる。
そして、スタンパ６０Ｂを取り外し、選択反射膜３２を
形成すると、透光性基板１に第１の信号記録層２、およ
び第２の信号記録層３が形成されたものが作製される
（図５の（ｆ））。ここで、第１の信号記録層２と第２
の信号記録層３との間には樹脂６が存在し、第１の信号
記録層２と第２の信号記録層３との距離は、約１０μｍ
となるように透光性基板１の一主面に第１の信号記録層
２を形成したものが樹脂６３に接触される。Referring to FIG. 5 and FIG.
Will be described. First, the surface of the stamper 60A on which the signal is recorded is covered with the resin 61 (FIG. 5A), and glass or polycarbonate 62 is brought into contact with the resin 61 (FIG. 5B). Then, ultraviolet rays (not shown) are irradiated from the glass or polycarbonate 62 side to make the resin 6.
1 is cured. Thereafter, when the resin 61 on which the signal recording surface is formed and the glass or polycarbonate 62 are removed from the stamper 60A, the pits 2 are formed on one main surface of the translucent substrate 1.
One in which one row is formed is produced. Here, the resin 61
And a glass or polycarbonate 62 made of a transparent substrate 1
Is configured. When the selective reflection film 22 is formed so as to cover the row of pits 21, the first main surface of the light-transmitting substrate 1 is formed.
Is formed (FIG. 5C). In this case, Ag 2 O and AgNO 3 are formed to a thickness of about 50 nm by the sputtering method as the selective reflection film 22. Thereafter, the signal recording surface of the stamper 60B having a signal recording surface different from the signal recording surface of the stamper 60A is covered with the resin 63 (FIG. 5D), and is formed on the resin 63 in the process of FIG. The first signal recording layer 2 formed on one main surface of the light-transmitting substrate 1 is brought into contact with the light-transmitting substrate 1 (FIG. 5E), and ultraviolet light (not shown) is irradiated from the light-transmitting substrate 1 side. The resin 63 is cured.
Then, when the stamper 60B is removed and the selective reflection film 32 is formed, a structure in which the first signal recording layer 2 and the second signal recording layer 3 are formed on the translucent substrate 1 is manufactured (FIG. 5). (F)). Here, the first signal recording layer 2 and the second signal recording layer 2
The resin 6 exists between the first signal recording layer 2 and the second signal recording layer 3 and the distance between the first signal recording layer 2 and the second signal recording layer 3 is about 10 μm.
The first signal recording layer 2 formed on one main surface of the light-transmitting substrate 1 is brought into contact with the resin 63 such that
【００２６】次に図６を参照して、第２の信号記録層３
まで作製されると、スタンパ６０Ａ、６０Ｂの信号記録
面と異なる信号記録面を有するスタンパ（図示省略）を
用いて、図５の（ｄ）〜（ｆ）の工程と同様の工程を行
うことにより透光性基板１に第１の信号記録層２、第２
の信号記録層３、および第３の信号記録層４が形成され
たものが作製される（図６の（ｇ））。そして、更に異
なる信号記録面を有するスタンパを用いて樹脂を射出成
形し、射出成形した樹脂をスタンパ（図示省略）から取
り外し、信号記録面を覆うようにＡｌをスパッタリング
法により約１００ｎｍ形成すると、保護層７の一主面に
第４の信号記録層５が形成されたものが作製される（図
６の（ｈ））。そして、図６の（ｇ）の工程で作製した
ものと、図６の（ｈ）の工程で作製したものとを貼り合
わせると多層光ディスク１０が完成する（図６の
（ｉ））。Next, referring to FIG. 6, the second signal recording layer 3
5A to 5F, a stamper (not shown) having a signal recording surface different from the signal recording surfaces of the stampers 60A and 60B is used. A first signal recording layer 2 and a second signal recording layer 2
A signal recording layer 3 and a third signal recording layer 4 are formed (FIG. 6 (g)). The resin is injection-molded using a stamper having a different signal recording surface, the injection-molded resin is removed from a stamper (not shown), and Al is formed to a thickness of about 100 nm by a sputtering method so as to cover the signal recording surface. One in which the fourth signal recording layer 5 is formed on one main surface of the layer 7 is manufactured (FIG. 6 (h)). Then, the optical disk manufactured in the step of FIG. 6G and the optical disk manufactured in the step of FIG. 6H are bonded together to complete the multilayer optical disk 10 (FIG. 6I).
【００２７】なお、多層光ディスク１０の作成方法につ
いては、上記説明した図５の（ａ）〜図５の（ｅ）まで
の工程と同じ工程を用いて第１の信号記録層２から第４
の信号記録層５まで形成した後、保護膜として紫外線硬
化樹脂を形成することにより多層光ディスク１０を作製
しても良い。また、本願発明に係る多層光ディスクは、
図１に示すものに限らず、図７に示す多層光ディスク２
０であっても良い。多層光ディスク２０は、多層光ディ
スク１０の第４の信号記録層５をピット５１列と、選択
反射膜５３とで構成したものであり、その他は多層光デ
ィスク１０と同じである。つまり、多層光ディスク２０
は、第１の信号記録層２、第２の信号記録層３、第３の
信号記録層４、および第４の信号記録層５の全てに選択
反射膜を用いたものである。The method for producing the multilayer optical disk 10 is the same as the above-described steps from FIG. 5 (a) to FIG. 5 (e) using the first signal recording layer 2 to the fourth signal recording layer.
After forming up to the signal recording layer 5, the multilayer optical disc 10 may be manufactured by forming an ultraviolet curing resin as a protective film. Further, the multilayer optical disc according to the present invention is:
The multilayer optical disc 2 shown in FIG. 7 is not limited to the one shown in FIG.
It may be 0. The multi-layer optical disc 20 has the same structure as the multi-layer optical disc 10 except that the fourth signal recording layer 5 of the multi-layer optical disc 10 is composed of a row of pits 51 and a selective reflection film 53. That is, the multilayer optical disc 20
The first signal recording layer 2, the second signal recording layer 3, the third signal recording layer 4, and the fourth signal recording layer 5 all use a selective reflection film.
【００２８】多層光ディスク２０も、図５、６の工程を
用いて容易に作製できる。また、多層光ディスク２０に
入射面８から入射したレーザ光ＬＢは、上記図２で説明
したのと同様に各信号記録層２、３、４、５に集光照射
され、温度が上昇して反射膜に変化した領域のみから信
号を検出する。また、多層光ディスク２０から検出され
るフォーカスエラー信号は、図４のＳ字のフォーカスエ
ラー信号１４を、Ｚ字のフォーカスエラー信号に代えた
ものである。即ち、全て信号記録層２、３、４、５から
Ｚ字のフォーカスエラー信号が検出されるため、多層光
ディスク２０においても、各信号記録層２、３、４、５
に容易にフォーカスジャンプできる。The multilayer optical disk 20 can be easily manufactured by using the steps shown in FIGS. The laser beam LB incident on the multilayer optical disc 20 from the incident surface 8 is condensed and irradiated on each of the signal recording layers 2, 3, 4, and 5 as described with reference to FIG. The signal is detected only from the area changed to the film. The focus error signal detected from the multilayer optical disc 20 is obtained by replacing the S-shaped focus error signal 14 in FIG. 4 with a Z-shaped focus error signal. That is, since a Z-shaped focus error signal is detected from all the signal recording layers 2, 3, 4, and 5, even in the multilayer optical disc 20, each of the signal recording layers 2, 3, 4, and 5 is detected.
Easy focus jump.
【００２９】本願においては、選択反射膜２２、３２、
４２、５３の透過率が８０％以上である場合、その選択
反射膜２２、３２、４２、５３は「透明膜である。」と
言う。上記説明においては、信号記録層の数は４層とし
て説明したが、本願発明に係る多層光ディスクは、これ
に限らず、一般にｍ個の信号記録層を有するものであれ
ば良い。その場合、全ての信号記録層が選択反射膜を有
していても良いし、レーザ光の入射面８からｍ−１番目
までの信号記録層には選択反射膜を用い、ｍ番目の信号
記録層には反射膜を用いたものであっても良い。In the present application, the selective reflection films 22, 32,
When the transmittance of the light-reflecting films 42 and 53 is 80% or more, the selective reflection films 22, 32, 42 and 53 are referred to as “transparent films”. In the above description, the number of signal recording layers is four, but the multi-layer optical disc according to the present invention is not limited to this, and generally may have any number m of signal recording layers. In this case, all the signal recording layers may have a selective reflection film, or the m-th signal recording is performed by using a selective reflection film for the m−1th signal recording layers from the laser light incident surface 8. A layer using a reflective film may be used.
【図１】本願発明に係る多層光ディスクの断面図であ
る。FIG. 1 is a sectional view of a multilayer optical disc according to the present invention.
【図２】図１に示す多層光ディスクの各信号記録層から
の反射率を示す図である。FIG. 2 is a diagram showing a reflectance from each signal recording layer of the multilayer optical disc shown in FIG.
【図３】図１に示す多層光ディスクの各信号記録層から
の信号検出を説明する図である。FIG. 3 is a view for explaining signal detection from each signal recording layer of the multilayer optical disc shown in FIG. 1;
【図４】図１に示す多層光ディスクの各信号記録層から
のフォーカスエラー信号を示す図である。FIG. 4 is a diagram showing focus error signals from respective signal recording layers of the multilayer optical disc shown in FIG.
【図５】図１に示す多層光ディスクの作製工程を示す図
である。FIG. 5 is a diagram showing a manufacturing process of the multilayer optical disc shown in FIG.
【図６】図１に示す多層光ディスクの作製工程を示す図
である。FIG. 6 is a diagram showing a manufacturing process of the multilayer optical disc shown in FIG.
【図７】本願発明に係る多層光ディスクの他の断面図で
ある。FIG. 7 is another sectional view of the multilayer optical disc according to the present invention.
【図８】従来の多層光ディスクの断面図である。FIG. 8 is a sectional view of a conventional multilayer optical disc.
１・・・透光性基板 ２・・・第１の信号記録層 ３・・・第２の信号記録層 ４・・・第３の信号記録層 ５・・・第４の信号記録層 ６、６１、６３・・・樹脂 ７・・・保護層 ８・・・入射面 １０、２０、３０・・・多層光ディスク １１、１２、１３・・・Ｚ字のフォーカスエラー信号 ２１、３１、４１、５１・・・ピット ２２、３２、４２、５３・・・選択反射膜 ４３・・・特定の領域 １４、１５、１６、１７・・・Ｓ字のフォーカスエラー
信号 ５２・・・反射膜 ６０Ａ、６０Ｂ・・・スタンパ ６２・・・ポリカーボネートDESCRIPTION OF SYMBOLS 1 ... Translucent board 2 ... 1st signal recording layer 3 ... 2nd signal recording layer 4 ... 3rd signal recording layer 5 ... 4th signal recording layer 6, 61, 63 ... resin 7 ... protective layer 8 ... incident surface 10, 20, 30 ... multilayer optical disk 11, 12, 13 ... Z-shaped focus error signal 21, 31, 41, 51 ... pits 22, 32, 42, 53 ... selective reflection film 43 ... specific area 14, 15, 16, 17 ... S-shaped focus error signal 52 ... reflection film 60A, 60B ..Stamper 62 ・ ・ ・ Polycarbonate
Claims (3)
号記録層の各々が、信号を記録したピット列と、前記ピ
ット列を覆うように形成された室温で透明膜であり、所
定の温度以上で反射膜に変化する選択反射膜とから成る
多層光ディスク。1. A semiconductor device comprising: m signal recording layers; each of the m signal recording layers is a pit row in which a signal is recorded, and a transparent film formed at room temperature to cover the pit row. And a selective reflection film that changes to a reflection film at a predetermined temperature or higher.
斜側からｍ−１番目までの信号記録層の各々が、信号を
記録したピット列と、前記ピット列を覆うように形成さ
れた室温で透明膜であり、所定の温度以上で反射膜に変
化する選択反射膜とから成り、 前記レーザ光の入斜側からｍ番目の信号記録層が、信号
を記録したピット列と、前記ピット列を覆うように形成
された反射膜とから成る多層光ディスク。2. A signal recording layer having m signal recording surfaces, wherein each of m-1st signal recording layers from the oblique side of the laser beam covers a pit row on which a signal is recorded and the pit row. The formed film is a transparent film at room temperature, and comprises a selective reflection film that changes to a reflection film at a predetermined temperature or more, and the m-th signal recording layer from the oblique side of the laser beam has a pit row in which a signal is recorded. And a reflection film formed so as to cover the pit row.
求項１または請求項２記載の多層光ディスク。3. The multilayer optical disc according to claim 1, wherein the selective reflection film is made of Ag 2 O.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31399499A JP4165974B2 (en) | 1999-11-04 | 1999-11-04 | Multi-layer optical disc |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31399499A JP4165974B2 (en) | 1999-11-04 | 1999-11-04 | Multi-layer optical disc |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001134981A true JP2001134981A (en) | 2001-05-18 |
| JP4165974B2 JP4165974B2 (en) | 2008-10-15 |
Family
ID=18047956
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31399499A Expired - Fee Related JP4165974B2 (en) | 1999-11-04 | 1999-11-04 | Multi-layer optical disc |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002031825A1 (en) * | 2000-10-11 | 2002-04-18 | Matsushita Electric Industrial Co., Ltd. | Optical record medium, optical information processing apparatus, and optical recording/reproducing method |
| WO2004114294A2 (en) * | 2003-06-26 | 2004-12-29 | Koninklijke Philips Electronics N.V. | Optical information carrier containing bragg reflectors |
| EP2224444A3 (en) * | 2009-02-11 | 2010-10-13 | Rohm and Haas Electronic Materials, L.L.C. | Optical data storage media and methods of manufacturing |
| US7859983B2 (en) | 2003-07-15 | 2010-12-28 | Sharp Kabushiki Kaisha | Optical disk and optical disk recording and reproducing device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7816601B2 (en) * | 2007-06-08 | 2010-10-19 | David Reginald Carver | Device and method for converting thermal energy into electrical energy |
-
1999
- 1999-11-04 JP JP31399499A patent/JP4165974B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002031825A1 (en) * | 2000-10-11 | 2002-04-18 | Matsushita Electric Industrial Co., Ltd. | Optical record medium, optical information processing apparatus, and optical recording/reproducing method |
| EP1327977A1 (en) * | 2000-10-11 | 2003-07-16 | Matsushita Electric Industrial Co., Ltd. | Optical record medium, optical information processing apparatus, and optical recording/reproducing method |
| US6987721B2 (en) | 2000-10-11 | 2006-01-17 | Matsushita Electric Industrial Co., Ltd. | Optical record medium, optical information processing apparatus, and optical recording/reproducing method |
| EP1327977A4 (en) * | 2000-10-11 | 2008-03-05 | Matsushita Electric Ind Co Ltd | Optical record medium, optical information processing apparatus, and optical recording/reproducing method |
| WO2004114294A2 (en) * | 2003-06-26 | 2004-12-29 | Koninklijke Philips Electronics N.V. | Optical information carrier containing bragg reflectors |
| WO2004114294A3 (en) * | 2003-06-26 | 2005-04-14 | Koninkl Philips Electronics Nv | Optical information carrier containing bragg reflectors |
| US7859983B2 (en) | 2003-07-15 | 2010-12-28 | Sharp Kabushiki Kaisha | Optical disk and optical disk recording and reproducing device |
| EP2224444A3 (en) * | 2009-02-11 | 2010-10-13 | Rohm and Haas Electronic Materials, L.L.C. | Optical data storage media and methods of manufacturing |
| US8389094B2 (en) | 2009-02-11 | 2013-03-05 | Rohm And Haas Electronic Materials Llc | Optical data storage media and methods of formation |
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| Publication number | Publication date |
|---|---|
| JP4165974B2 (en) | 2008-10-15 |
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