JP3908478B2 - Optical disc having convex portions - Google Patents

Optical disc having convex portions Download PDF

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Publication number
JP3908478B2
JP3908478B2 JP2001128022A JP2001128022A JP3908478B2 JP 3908478 B2 JP3908478 B2 JP 3908478B2 JP 2001128022 A JP2001128022 A JP 2001128022A JP 2001128022 A JP2001128022 A JP 2001128022A JP 3908478 B2 JP3908478 B2 JP 3908478B2
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Japan
Prior art keywords
substrate
optical disc
curable resin
radiation curable
thickness
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Expired - Fee Related
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JP2001128022A
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JP2002184037A (en
JP2002184037A5 (en
Inventor
和也 久田
林  一英
和夫 井上
鋭二 大野
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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Publication of JP2002184037A5 publication Critical patent/JP2002184037A5/ja
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/1429Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation characterised by the way of heating the interface
    • B29C65/1435Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation characterised by the way of heating the interface at least passing through one of the parts to be joined, i.e. transmission welding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/1477Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation making use of an absorber or impact modifier
    • B29C65/1483Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation making use of an absorber or impact modifier coated on the article
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/48Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using adhesives, i.e. using supplementary joining material; solvent bonding
    • B29C65/4805Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using adhesives, i.e. using supplementary joining material; solvent bonding characterised by the type of adhesives
    • B29C65/483Reactive adhesives, e.g. chemically curing adhesives
    • B29C65/4845Radiation curing adhesives, e.g. UV light curing adhesives
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/48Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using adhesives, i.e. using supplementary joining material; solvent bonding
    • B29C65/52Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using adhesives, i.e. using supplementary joining material; solvent bonding characterised by the way of applying the adhesive
    • B29C65/521Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using adhesives, i.e. using supplementary joining material; solvent bonding characterised by the way of applying the adhesive by spin coating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/01General aspects dealing with the joint area or with the area to be joined
    • B29C66/05Particular design of joint configurations
    • B29C66/10Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112Single lapped joints
    • B29C66/1122Single lap to lap joints, i.e. overlap joints
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/40General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/41Joining substantially flat articles ; Making flat seams in tubular or hollow articles
    • B29C66/45Joining of substantially the whole surface of the articles
    • B29C66/452Joining of substantially the whole surface of the articles the article having a disc form, e.g. making CDs or DVDs
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/70General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/1403Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation characterised by the type of electromagnetic or particle radiation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/14Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
    • B29C65/1403Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation characterised by the type of electromagnetic or particle radiation
    • B29C65/1406Ultraviolet [UV] radiation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/70General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29LINDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2017/00Carriers for sound or information
    • B29L2017/001Carriers of records containing fine grooves or impressions, e.g. disc records for needle playback, cylinder records
    • B29L2017/003Records or discs
    • B29L2017/005CD''s, DVD''s

Description

【0001】
【発明の属する技術分野】
本発明は、光ディスクおよびその製造方法に関し、特にたとえば、レーザ光が入射する側の基板を薄くした光ディスクおよびその製造方法に関する。
【0002】
【従来の技術】
近年、情報記録の分野では様々な光情報記録に関する研究が進められている。この光情報記録は高密度化が可能であり、また、非接触で記録・再生が行え、それを安価に実現できる方式として幅広い用途での応用が実現されつつある。現在の光ディスクとしては、厚さ1.2mmの透明樹脂基板に情報層を設け、それをオーバーコートによって保護した構造、あるいは0.6mmの透明樹脂基板の一方もしくは両方に情報層を設け、それら2枚を貼り合わせた構造が用いられている。
【0003】
近年、光ディスクの記録密度を上げる方法として、対物レンズの開口数(NA)を大きくする方法や、使用するレーザの波長を短くする方法が検討されている。このとき記録・再生側基板(レーザ光が入射する側の基板)の厚みが薄いほうが、レーザスポットが受ける収差の影響を小さくでき、ディスクの傾き角度(チルト)の許容値を大きくできる。このことから、記録・再生側基板の厚さを0.1mm程度にし、NAを0.85程度、レーザの波長を400nm程度にすることが提案されている。
【0004】
現在のDVD(デジタル バーサタイル ディスク)では、成膜等の処理を行った厚さ0.6mmの2枚の透明樹脂基板を放射線硬化性樹脂で貼り合わせるという方法が主に用いられている。高密度化のために記録・再生側基板の厚みが0.1mm程度になったときも、現在と同様の設備を用いて同様の方法で貼り合わせることが望ましい。
【0005】
【発明が解決しようとする課題】
しかしながら、2枚の基板を貼りあわせる光ディスクでは、高密度記録のために記録・再生側基板の厚みが薄くなると、記録・再生側基板の剥離や割れが生じやすいという課題があり、耐久性を向上させることが求められている。また、2枚の基板を貼りあわせる際にその中心がずれると、回転させたときにぶれが生じるため、2枚の基板の中心を高精度で一致させることが求められている。さらに、これらの光ディスクを容易に製造する方法も求められている。
【0006】
そのため、本発明は、2枚の基板を貼りあわせることによって高密度記録が可能な光ディスクおよびその製造方法を提供することを目的とする。
【0007】
【課題を解決するための手段】
上記目的を達成するため、本発明の光ディスクは、一主面に信号領域を備え中心孔Aを有する第1の基板と、前記第1の基板の前記一主面側に貼り合わされた、前記第1の基板よりも薄い透光性の第2の基板とを備える光ディスクであって、前記第2の基板は前記中心孔Aよりも直径が大きい中心孔Bを有し、前記第1の基板と前記第2の基板とが、前記第1の基板と前記第2の基板との間に配置された接着部材によって貼り合わされており、
前記第1の基板は、前記一主面側に、前記第中心孔Aを囲むように円環状に形成され且つ外径が前記中心孔Bの直径以下である凸部と、前記凸部を囲むように円環状に形成された凹部とを備え、前記凸部の前記一主面からの高さが、前記第2の基板の厚さと前記接着部材の厚さとの和よりも大きいことを特徴とする。この光ディスクによれば、高密度記録が可能であると共にハンドリングが容易な光ディスクが得られる。これによって、ディスクをハンドリングした時に接触部分が割れたり剥がれたりすることを防止できる。なお、本明細書で用いる「放射線」は、電子線および紫外線などの粒子波および電磁波を含む。
【0008】
【0009】
上記光ディスクでは、前記凸部の前記一主面からの高さが、0.05mm以上0.5mm以下であることが好ましい。
【0010】
上記光ディスクでは、前記接着部材は、少なくとも前記第2の基板の内周端から外周端にかけて配置されていることが好ましい。
【0011】
上記光ディスクでは、前記第2の基板の厚さが、0.03mm以上0.3mm以下であってもよい。この構成によれば、特に高密度に情報を記録することが可能な光ディスクが得られる。
【0012】
上記光ディスクでは、前記第1の基板の前記信号領域に、複数の信号記録層が形成されていることが好ましい
また、上記光ディスクでは、前記接着部材が放射線硬化性樹脂であってもよい。その構成によれば、製造が容易になる。
【0013】
【0014】
【0015】
上記光ディスクでは、前記接着部材の平均厚さが、0.5μm以上30μm以下であってもよい。
上記光ディスクでは、情報の再生のために照射されるレーザの波長が、450nm以下であることが好ましい。
【0016】
【0017】
【0018】
【0019】
【0020】
【0021】
【0022】
【0023】
【0024】
【0025】
【0026】
【0027】
【0028】
【0029】
【0030】
【0031】
【0032】
【0033】
【0034】
【0035】
【0036】
【0037】
【0038】
【0039】
【0040】
【0041】
【0042】
【0043】
【0044】
【0045】
【0046】
【0047】
【発明の実施の形態】
以下、図面を参照しながら本発明の実施の形態について説明する。なお、同様の部分については、同一の符号を付して重複する説明を省略する場合がある。
【0048】
参考例
まず、凸部を備えない光ディスクについて一例を説明する。図1(A)に平面図を、図1(B)に断面図を示す。
【0049】
図1を参照して、光ディスク10は、第1の基板11(ハッチングを省略する。以下、第1の基板のハッチングは同様に省略する場合がある。)と、第1の基板11に貼り合わされた第2の基板12とを備える。そして、第1の基板11と第2の基板12とは、第1の基板11と第2の基板12との間に配置された放射線硬化性樹脂(接着部材)13によって貼り合わされている。
【0050】
第1の基板11は、一主面11aに信号領域SAを備える。信号領域SAには、信号記録層14が形成されている。信号領域SAの構造は、光ディスクの用途などによって異なる。光ディスク10が再生専用のディスクである場合には、たとえば、一主面11aのうち信号領域SAの部分には凹凸形状のピットが形成され、ピット上には信号記録層としてAlなどからなる膜が形成される。また、光ディスク10が記録・再生用のディスクである場合には、信号領域SAには、記録・再生が可能なように、相変化材料や色素などから構成される記録膜が形成される。
【0051】
第1の基板11は、その中央部に、直径がdA(たとえば15mm)の円形の中心孔Aを備える。第1の基板11の厚さは、特に限定がないが、第2の基板12の厚さとの合計が、0.5mm〜0.7mmまたは1.1mm〜1.3mmの範囲内となることが好ましい。第1の基板11の外径については特に限定はなく、たとえば120mmである。第1の基板11は、たとえば、ポリカーボネート樹脂やアクリル樹脂などの熱可塑性樹脂、またはビニルエステル樹脂やポリエステル樹脂などの熱硬化性樹脂などからなる。
【0052】
第2の基板12は、第1の基板11よりも薄い基板であり、透光性である。第2の基板12の厚さは、0.03mm〜0.3mmの範囲内であり、0.03mm〜0.12mmの範囲内であることがより好ましい。具体的には、第2の基板12の厚さは、たとえば、0.05mmや0.1mmである。第1の基板11の厚さと第2の基板12の厚さとの合計を、1.1mm〜1.3mmの範囲内とすることによって、既存の光ディスクとの互換性を確保できる。また、厚さの合計を、0.5mm〜0.7mm、または1.1mm〜1.3mmの範囲内とすることによって、光ディスクの従来の製造装置を利用できる。
【0053】
第2の基板12は、信号を記録・再生するために照射されるレーザ光(好ましくは波長が450nm以下)が照射される側の基板であり、透光性の材料からなる。具体的には、第2の基板12は、たとえば、ポリカーボネート樹脂やアクリル樹脂などの熱可塑性樹脂、またはビニルエステル樹脂やポリエステル樹脂などの熱硬化性樹脂などからなる。第2の基板12は、その中央部に、直径がdBの円形の中心孔Bを備える。図1(A)に示すように、中心孔Bは、クランプ領域Cよりも大きいことが好ましい。
【0054】
ここで、クランプ領域Cは、記録・再生のために光ディスク10を搬送したり回転させたりする際に保持される領域である。第1の基板11のクランプ領域Cの厚さは1.1mm以上1.3mm以下であることが好ましい。
【0055】
接着部材である放射線硬化性樹脂13は、少なくとも第2の基板の内周端12sから外周端12tまで配置されている。すなわち、放射線硬化性樹脂13は、第2の基板12の主面のうち、第1の基板11側の主面の全面に少なくとも配置されている。なお、放射線硬化性樹脂13は、第1の基板の内周端11sまで配置されていてもよい。放射線硬化性樹脂13は、放射線によって硬化する樹脂である。放射線硬化性樹脂13には、たとえば、紫外線照射によって硬化する紫外線硬化性樹脂や、電子線照射によって硬化する樹脂などを用いることができる。図1(A)に示すように、放射線硬化性樹脂13は、クランプ領域Cよりも外周側に配置されているか、または、クランプ領域Cのすべてを覆うように配置されていることが好ましい。放射線硬化性樹脂13の平均厚さは、0.5μm〜30μmの範囲内であることが好ましい。なお、放射線硬化性樹脂13の代わりに、両面テープなどの接着部材を用いてもよい。
【0056】
上記実施形態1の光ディスク10では、光入射側の第2の基板12が薄いため、高密度記録が可能である。また、第2の基板12の中心孔Bの直径が第1の基板11の中心孔Aの直径よりも大きいため、第2の基板12の剥離や割れが生じにくくハンドリングが容易である。さらに、第2の基板12の内周端12sにまで放射線硬化性樹脂が配置されているため、第2の基板12の剥離や割れが生じにくくハンドリングが容易である。
【0057】
なお、第1の基板11は、一主面11a側に、中心孔Aを囲むように円環状に形成され且つ外径が中心孔Bの直径以下である凸部、および、中心孔Aを囲むように円環状に形成され且つ直径が中心孔Bの直径以下である凹部から選ばれる少なくとも1つを備えることが好ましい。
【0058】
(実施形態1)
第1の基板が、上記円環状の凸部を備える場合の光ディスク20について、平面図を図2(A)に、断面図を図2(B)に示す。また、第1の基板が他の形状の凸部を備える場合の光ディスク30について、平面図を図3(A)に、断面図を図3(B)に示す。また、第1の基板が、円環状の凸部と円環状の凹部とを備える場合の第1の基板51および56について、断面図をそれぞれ図(A)および(B)に示す。なお、第1の基板21、31、51および56は、凸部および凹部以外の部分については第1の基板11と同様である。すなわち、一主面21a、31a、51aおよび56aは、一主面11aに対応する。また、光ディスク20および0は、それぞれ、第1の基板21および1を除いて光ディスク10と同様であるため、重複する説明は省略する。
【0059】
図2(A)および(B)に示すように、光ディスク20の第1の基板21は、信号領域SAが形成された一主面21a側に、中心孔Aを囲むように円環状に形成され且つ外径L1が中心孔Bの直径dBと等しい凸部22を備える。凸部22によって、以下説明するように光ディスクの製造が容易になる。また、凸部22の高さ(一主面21aからの高さ)は、0.05mm以上0.5mm以下であることが好ましい。また、凸部22の高さは、図2(B)に示すように、第2の基板の厚さと放射線硬化性樹脂13の厚さとの和よりも大きいことが好ましい(以下の凸部においても同様である)。これによって、光ディスク20を重ね合わせて保持・保存する際に、再生面が他の光ディスクに直接触れることがなくなり、再生面が傷つくことがなくなる。また、図2(B)に示すように、凸部22は、第2の基板12の内周端に接するように形成する(凸部22の外径L1と中心孔Bの直径dBとを等しくする)ことが好ましい(以下の凸部においても同様である)。これによって、第1の基板11と第2の基板12との偏心を抑制できる。さらに、記録・再生時に、クランプのセンターコーンやモーターターンテーブルが第2の基板12と接触しないため、第2の基板12の薄形化による強度の低下にも対応でき、また、チルトが大きくなることを抑制できる。
【0060】
図3(A)および(B)に示すように、光ディスク30の第1の基板31は、信号領域SAが形成された一主面31a側に、中心孔Aを囲むように円環状に形成され且つ外径L1が中心孔Bの直径dBと等しい凸部(段差)32を備える。この場合の凸部32は、第1の基板31の内周端にまで形成されている。
【0061】
【0062】
(A)に示すように、第1の基板51は、信号領域SAが形成された一主面51a側に、中心孔Aを囲むように円環状に形成され且つ外径が中心孔Bの直径以下である凸部22と、凸部22を囲むように円環状に配置された凹部42とを備える。これによって、凸部および凹部の効果が得られる。
【0063】
(B)に示すように、第1の基板56は、信号領域SAが形成された一主面56a側に、中心孔Aを囲むように円環状に形成され且つ外径が中心孔Bの直径以下である凸部32と、凸部32を囲むように円環状に配置された凹部42とを備える。これによって、凸部および凹部の効果が得られる。
【0064】
なお、上述した光ディスク20および0も、光ディスク10と同様の効果を有することはいうまでもない。
【0065】
なお、実施形態では、第1の基板のみに信号記録層が形成されている光ディスクについて説明した。しかし、本発明の光ディスクおよびその製造方法では、第2の基板に信号記録層が形成されていてもよい(以下同様である)。たとえば、本発明の光ディスクおよびその製造方法では、第2の基板にも半透明の信号記録層を形成し、第1の基板および第2の基板がともに信号記録層を備えてもよい。また、第1の基板に、複数の信号記録層を形成してもよい(以下同様である)。これらの構成によって、2層構造の光ディスクが得られる。この場合には、第2の基板側から入射させたレーザ光によって、両方の信号記録層に記録された情報を再生できる。
【0066】
光ディスクの製造方法
ここでは、本発明の光ディスクの製造方法について一例を説明する。参考例で説明した光ディスク10を製造する場合の製造工程を図に示すが、上述した光ディスク20および30を製造する場合も同様である。
【0067】
ここで説明する製造方法では、図(A)に示すように、一主面11aに信号領域SAを備え中心孔Aを有する第1の基板11と、中心孔Aよりも直径が大きい中心孔Bを有し第1の基板11よりも薄い透光性の第2の基板12とを、一主面11aが内側になるように硬化前の放射線硬化性樹脂13aを挟んで密着させる(工程(a))。このとき、第2の基板12の少なくとも内周端12sから外周端12tまで、放射線硬化性樹脂13aを配置する。なお、放射線硬化性樹脂13aは、第1の基板11の内周端11sまで配置されてもよい参考例で説明したように、クランプ領域Cにかからないように配置されてもよい
【0068】
第1の基板11の信号領域SAは、たとえば、射出成形法やフォトポリマー法によって樹脂を成形して凹凸形状のピットを形成したのち、膜厚がたとえば50nmのAlからなる反射膜(信号記録層14)をスパッタリング法で形成することによって形成できる。また、信号領域SAを相変化膜や色素膜などで形成する場合には、スパッタリング法や蒸着法によって形成できる。第1の基板11は、たとえば、厚さが1.1mm、直径が120mm、中心孔径が15mmのポリカーボネート製基板である。
【0069】
第2の基板12は、たとえば、厚さが90μm、外径が120mm、中心孔径が40mmのポリカーボネート製またはアクリル製基板である。第2の基板12は、射出成形法やキャスティング法によって形成することができる。第2の基板12の厚さは、0.03mm〜0.3mmの範囲内である。
【0070】
その後、図(B)に示すように、放射線硬化性樹脂13aに放射線(紫外線や電子線など)を照射することによって、放射線硬化性樹脂13aを硬化させて硬化後の放射線硬化性樹脂13とし、第1の基板11と第2の基板12とを貼り合わせる(工程(b))。放射線は、連続的に照射してもよいし、パルス的に照射してもよい(以下の製造方法においても同様である)。このようにして、光ディスク10を製造できる。
【0071】
以下に、上記第1の工程において、放射線硬化性樹脂13aを挟んで第1の基板11と第2の基板12とを密着させる方法について、2通りの方法を説明する。
【0072】
第1の方法は、第1の基板11と第2の基板12とによって放射線硬化性樹脂13aを挟んで一体としたのち、一体となった第1の基板11と第2の基板12とを回転させることによって、放射線硬化性樹脂13aを延伸する方法である。この方法について、工程の一例を図に示す。図の工程では、まず、図(A)に示すように、第1の基板11上にノズル71によって円環状に放射線硬化性樹脂13aを塗布する。この際、第1の基板11またはノズル71を低速(20rpm〜120rpm)で回転させる。また、第2の基板12の内周端12sまできっちりと接着するために、放射線硬化性樹脂13aを第1の基板11上であって内周端12sが配置される位置(たとえば、半径20mm〜25mmの位置)に塗布する。
【0073】
次に、図(B)に示すように、第1の基板11と第2の基板12とを、同心円になるように対向させ重ね合わせる。ただし、クランプ領域Cに放射線硬化性樹脂13aが付着するとチルトへの影響が大きくなるため、図(C)に示すように、クランプ領域Cの外周側に円環状に紫外線などの放射線72を照射して、これ以上内周に放射線硬化性樹脂13aが浸入するのを防ぐことが好ましい。すなわち、工程(a)は、第1の基板11を回転させる前に、信号領域SAよりも内側に配置された放射線硬化性樹脂13aの少なくとも一部を硬化させる工程を含んでもよい(以下の第2の方法においても同様である)。なお、放射線硬化性樹脂13aは、第2の基板12上に塗布してもよい。
【0074】
その後、図(D)に示すように、第1の基板11と第2の基板12とを重ね合わせたままの状態で、2枚の基板を高速(1000rpm〜10000rpm)で回転させ、外周部分まで放射線硬化性樹脂13aを拡散させる。これによって、接着部分に気泡が入りにくく、また余分な放射線硬化性樹脂13aが振り切られて第1の基板11と第2の基板12との間から排出される。このようにして、工程(a)を行うことができる。
【0075】
なお、上記工程において、放射線硬化性樹脂13aの厚さを均一にするためには、樹脂拡散のための基板の回転数・回転時間や放射線硬化性樹脂13aの厚さに応じて放射線硬化性樹脂13aの粘度を選択することが好ましい。一般に、上記方法では放射線硬化性樹脂13aの厚さは内周側で薄くなり、外周側で厚くなりやすい。光ディスクの高密度化のために検討されているような波長400nmのレーザ、対物レンズのNA0.85といった条件での記録・再生を行うためには、放射線硬化性樹脂13の膜厚バラツキは、その中心値(第2の基板12の厚さと放射線硬化性樹脂13の厚さとの和であり、たとえば0.1mm)に対して±3μm程度の範囲に収めることが要求される。
【0076】
上記第1の方法における、放射線硬化性樹脂13aの粘度と硬化後の放射線硬化性樹脂13の面内ばらつきとの関係を表1に示す。
【0077】
【表1】

Figure 0003908478
【0078】
表1から明らかなように、放射線硬化性樹脂13aの粘度を10mPa・s以上1500mPa・s以下とすることによって、硬化後の放射線硬化性樹脂13の膜厚のばらつきを6μm以下、すなわち±3μm以下とすることができる。
【0079】
また、上記第1の方法における放射線硬化性樹脂13aの粘度とタクトタイムとの関係を表2に示す。
【0080】
【表2】
Figure 0003908478
【0081】
表2から明らかなように、タクトタイムを短縮するためには放射線硬化性樹脂13aの粘度を10mPa・s〜600mPa・sの範囲内とすることが好ましい。
【0082】
次に、第1の工程を行うための第2の方法について説明する。第2の方法は、放射線硬化性樹脂13aを第1の基板11上に滴下したのち、第1の基板11を回転させることによって放射線硬化性樹脂13aを第1の基板11上に塗布し、次いで、第1の基板11と第2の基板12とを放射線硬化性樹脂13aを挟んで密着させる方法である。この方法について、工程の一例を図に示す。第2の方法では、まず、図(A)に示すように、第1の基板11上にノズル71によって円環状に放射線硬化性樹脂13aを塗布する。この工程は、図(A)で説明した工程と同様である。
【0083】
次に、図(B)に示すように、第1の基板11を高速(1000rpm〜10000rpm)で回転することによって、放射線硬化性樹脂13aを外周部まで延伸する。このとき、図(C)の工程で説明したように、クランプ領域Cの外周側の放射線硬化性樹脂13aに円環状にレーザ光を照射してもよい。
【0084】
その後、図(C)に示すように、第1の基板11と第2の基板12とを同心円となるように重ね合わせ、密着させる。このようにして、上記工程(a)を行うことができる。なお、重ね合わせの際に適当な圧力を均一に加えてやることで、放射線硬化性樹脂13aの分布をさらに均一にすることができる。このとき、気泡が入らないように注意する必要がある。気泡が入らないようにするためには、図に示すように、基板を密着させる工程を真空チャンバ90内、すなわち真空雰囲気中で行うことが好ましい。
【0085】
上記第2の方法における、放射線硬化性樹脂13aの粘度と硬化後の放射線硬化性樹脂13の面内ばらつきとの関係を表3に示す。
【0086】
【表3】
Figure 0003908478
【0087】
表3から明らかなように、放射線硬化性樹脂13aの粘度を10mPa・s以上15000mPa・s以下とすることによって、硬化後の放射線硬化性樹脂13の膜厚のばらつきを6μm以下(±3μm以下)とすることができる。
【0088】
また、上記第1の方法における放射線硬化性樹脂13aの粘度とタクトタイムとの関係を表4に示す。
【0089】
【表4】
Figure 0003908478
【0090】
表4から明らかなように、タクトタイムを短縮するためには放射線硬化性樹脂13aの粘度を10mPa・s〜1000mPa・sの範囲内とすることが好ましい。
【0091】
以上のように、上記の光ディスクの製造方法によれば、光ディスクを容易に製造できる。なお、上記第2の方法では、第2の基板に放射線硬化性樹脂を塗布してから、第1の基板と密着させるようにしてもよい。
【0092】
なお、上記製造方法では、第1の基板11の代わりに、実施形態1で説明した第1の基板21、31、51または56を用いてもよい。これらの基板を用いることによって、円環状の凸部よりも内周側に放射線硬化性樹脂13aが塗布されることを防止できる。この場合、円環状に放射線を照射する工程は行わなくてもよくなるため、生産が容易になる。また、凸部の外径L1を第2の基板12の直径dBと同じ大きさとすることによって、第1の基板と第2の基板とを貼り合わせる際に、偏心が生じることを防止できる。
【0093】
【0094】
【0095】
【0096】
【0097】
【0098】
【0099】
【0100】
【0101】
【0102】
【0103】
【0104】
【0105】
【0106】
【0107】
【0108】
【0109】
【0110】
【0111】
【0112】
【0113】
【0114】
【0115】
【0116】
【0117】
【0118】
【0119】
【0120】
【0121】
【0122】
【0123】
【0124】
【0125】
【0126】
【0127】
【0128】
【0129】
【0130】
【0131】
【0132】
【0133】
【0134】
【0135】
【0136】
以上、本発明の実施の形態について例を挙げて説明したが、本発明は、上記実施の形態に限定されず本発明の技術的思想に基づき他の実施形態に適用することができる。
【0137】
【発明の効果】
以上説明したように、本発明の光ディスクによれば、高密度記録が可能であると共にハンドリングが容易な光ディスクが得られる。
【0138】
また、本発明の製造方法によれば、高密度記録が可能な光ディスクを容易に製造できる。
【0139】
【図面の簡単な説明】
【図1】 参考例の光ディスクについて一例を示す(A)平面図および(B)断面図である。
【図2】 本発明の光ディスクについて一例を示す(A)平面図および(B)断面図である。
【図3】 本発明の光ディスクについてその他の一例を示す(A)平面図および(B)断面図である。
【図4】 本発明の光ディスクに用いる基板について(A)一例および(B)他の一例を示す断面図である。
【図5】本発明の光ディスクの製造方法について一例を示す工程断面図である。
【図6】本発明の光ディスクの製造方法について一部の工程を示す工程断面図である。
【図7】本発明の光ディスクの製造方法について一部の工程を示す工程断面図である。
【図8】本発明の光ディスクの製造方法について一部の工程を示す断面図である
【符号の説明】
10、20、3光ディスク
11、21、31、51、5 第1の基板
11a、12a、21a、31a、51a、56a 一主面
第2の基板
12s 内周端
12t 外周端
13、13放射線硬化性樹脂(接着部材)
14 信号記録層
22、32 凸部
42 凹
71 ノズル
、B 中心孔
C クランプ領域
SA 信号領域
dA、dB、L直径[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc and a manufacturing method thereof, and more particularly to an optical disc having a thin substrate on which laser light is incident and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, research on various optical information recording has been advanced in the field of information recording. This optical information recording can be densified, can be recorded / reproduced in a non-contact manner, and is being realized in a wide range of applications as a method that can be realized at low cost. As an optical disk at present, an information layer is provided on a transparent resin substrate having a thickness of 1.2 mm, and the information layer is protected by an overcoat, or an information layer is provided on one or both of a 0.6 mm transparent resin substrate. A structure in which sheets are bonded together is used.
[0003]
In recent years, methods for increasing the numerical aperture (NA) of an objective lens and methods for shortening the wavelength of a laser to be used have been studied as methods for increasing the recording density of an optical disk. At this time, if the thickness of the recording / reproducing side substrate (the substrate on which the laser beam is incident) is thinner, the influence of the aberration received by the laser spot can be reduced, and the allowable value of the disc tilt angle (tilt) can be increased. For this reason, it has been proposed that the thickness of the recording / reproducing side substrate is about 0.1 mm, the NA is about 0.85, and the laser wavelength is about 400 nm.
[0004]
In the current DVD (Digital Versatile Disc), a method is mainly used in which two transparent resin substrates having a thickness of 0.6 mm subjected to processing such as film formation are bonded with a radiation curable resin. Even when the thickness of the recording / reproducing side substrate becomes about 0.1 mm due to high density, it is desirable to use the same equipment as in the present method to bond them together.
[0005]
[Problems to be solved by the invention]
However, with optical discs that bond two substrates together, there is a problem that if the recording / reproducing side substrate becomes thin for high-density recording, the recording / reproducing side substrate tends to peel off or crack , which improves durability. It is demanded to make it. Further, when two of its in attaching the substrate center is shifted, since the blur occurs when rotating, it is possible to match the center of the two substrates with high accuracy are required. Further, a method for easily manufacturing these optical discs is also required.
[0006]
Therefore, an object of the present invention is to provide an optical disc capable of high-density recording by bonding two substrates and a manufacturing method thereof.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an optical disc of the present invention includes a first substrate having a signal region on one principal surface and having a center hole A, and the first substrate bonded to the one principal surface side of the first substrate. An optical disc comprising a light- transmitting second substrate thinner than the first substrate , the second substrate having a central hole B having a diameter larger than that of the central hole A; The second substrate is bonded by an adhesive member disposed between the first substrate and the second substrate ,
Said first substrate, on the one main surface side, and the convex portion and the outer diameter is formed in an annular shape so as to surround the first center hole A is less than the diameter of the central hole B, surrounds the protrusion And the height of the convex portion from the one main surface is larger than the sum of the thickness of the second substrate and the thickness of the adhesive member. To do. According to this optical disc, it is possible to obtain an optical disc that can be recorded at high density and is easy to handle. This prevents the contact portion from being cracked or peeled off when the disc is handled. The “radiation” used in the present specification includes particle waves such as electron beams and ultraviolet rays, and electromagnetic waves.
[0008]
[0009]
In the above optical disc, the height from the main surface of the front Kitotsu portion is preferably not 0.05mm or 0.5mm or less.
[0010]
In the optical disc, it is preferable that the adhesive member is disposed at least from the inner peripheral end to the outer peripheral end of the second substrate.
[0011]
In the optical disc, the thickness of the second substrate may be not less than 0.03 mm and not more than 0.3 mm. According to this configuration, an optical disc capable of recording information at a particularly high density can be obtained.
[0012]
In the optical disc, it is preferable that a plurality of signal recording layers are formed in the signal region of the first substrate .
In the optical disc, the adhesive member may be a radiation curable resin. According to the structure, manufacture becomes easy.
[0013]
[0014]
[0015]
In the optical disc, an average thickness of the adhesive member may be not less than 0.5 μm and not more than 30 μm.
In the optical disc, the wavelength of the laser irradiated for information reproduction is preferably 450 nm or less.
[0016]
[0017]
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
[0028]
[0029]
[0030]
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
[0045]
[0046]
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same part, the same code | symbol may be attached | subjected and the overlapping description may be abbreviate | omitted.
[0048]
( Reference example )
First, an example of an optical disc that does not have a convex portion will be described . FIG. 1A is a plan view and FIG. 1B is a cross-sectional view.
[0049]
Referring to FIG. 1, an optical disc 10 is bonded to a first substrate 11 (hatching is omitted. Hereinafter, hatching of the first substrate may be omitted in the same manner) and the first substrate 11. And a second substrate 12. Then, the first substrate 11 and the second substrate 12 are bonded together by a radiation curable resin (adhesive member) 13 disposed between the first substrate 11 and the second substrate 12.
[0050]
The first substrate 11 includes a signal area SA on one main surface 11a. A signal recording layer 14 is formed in the signal area SA. The structure of the signal area SA differs depending on the use of the optical disk. When the optical disk 10 is a read-only disk, for example, a pit having an uneven shape is formed in the signal area SA of the main surface 11a, and a film made of Al or the like is formed on the pit as a signal recording layer. It is formed. When the optical disk 10 is a recording / reproducing disk, a recording film made of a phase change material, a dye, or the like is formed in the signal area SA so as to enable recording / reproducing.
[0051]
The first substrate 11 includes a circular center hole A having a diameter of dA (for example, 15 mm) at the center thereof. Although the thickness of the 1st board | substrate 11 does not have limitation in particular, The sum total with the thickness of the 2nd board | substrate 12 may be in the range of 0.5 mm-0.7 mm or 1.1 mm-1.3 mm. preferable. There is no limitation in particular about the outer diameter of the 1st board | substrate 11, For example, it is 120 mm. The first substrate 11 is made of, for example, a thermoplastic resin such as polycarbonate resin or acrylic resin, or a thermosetting resin such as vinyl ester resin or polyester resin.
[0052]
The second substrate 12 is a substrate thinner than the first substrate 11 and is translucent. The thickness of the second substrate 12 is in the range of 0.03 mm to 0.3 mm, and more preferably in the range of 0.03 mm to 0.12 mm. Specifically, the thickness of the second substrate 12 is, for example, 0.05 mm or 0.1 mm. By making the sum of the thickness of the first substrate 11 and the thickness of the second substrate 12 within a range of 1.1 mm to 1.3 mm, compatibility with an existing optical disc can be ensured. Moreover, the conventional manufacturing apparatus of an optical disk can be utilized by making the total thickness into the range of 0.5 mm-0.7 mm or 1.1 mm-1.3 mm.
[0053]
The second substrate 12 is a substrate irradiated with laser light (preferably having a wavelength of 450 nm or less) irradiated for recording / reproducing signals, and is made of a light-transmitting material. Specifically, the second substrate 12 is made of, for example, a thermoplastic resin such as a polycarbonate resin or an acrylic resin, or a thermosetting resin such as a vinyl ester resin or a polyester resin. The second substrate 12 includes a circular center hole B having a diameter of dB at the center thereof. As shown in FIG. 1A, the center hole B is preferably larger than the clamp region C.
[0054]
Here, the clamp area C is an area held when the optical disk 10 is transported or rotated for recording / reproduction. The thickness of the clamp region C of the first substrate 11 is preferably 1.1 mm or greater and 1.3 mm or less.
[0055]
The radiation curable resin 13 as an adhesive member is disposed at least from the inner peripheral end 12s to the outer peripheral end 12t of the second substrate. That is, the radiation curable resin 13 is disposed at least on the entire main surface of the second substrate 12 on the first substrate 11 side. The radiation curable resin 13 may be disposed up to the inner peripheral end 11s of the first substrate. The radiation curable resin 13 is a resin that is cured by radiation. As the radiation curable resin 13, for example, an ultraviolet curable resin that is cured by ultraviolet irradiation, a resin that is cured by electron beam irradiation, or the like can be used. As shown in FIG. 1A, it is preferable that the radiation curable resin 13 is disposed on the outer peripheral side of the clamp region C or is disposed so as to cover the entire clamp region C. The average thickness of the radiation curable resin 13 is preferably in the range of 0.5 μm to 30 μm. In place of the radiation curable resin 13, an adhesive member such as a double-sided tape may be used.
[0056]
In the optical disc 10 of the first embodiment, since the second substrate 12 on the light incident side is thin, high-density recording is possible. In addition, since the diameter of the center hole B of the second substrate 12 is larger than the diameter of the center hole A of the first substrate 11, the second substrate 12 is not easily peeled or cracked, and handling is easy. Furthermore, since the radiation curable resin is disposed up to the inner peripheral end 12s of the second substrate 12, the second substrate 12 is not easily peeled or cracked, and handling is easy.
[0057]
The first substrate 11 is formed in an annular shape so as to surround the center hole A on the one main surface 11a side, and surrounds the center hole A and the convex portion whose outer diameter is equal to or smaller than the diameter of the center hole B. Thus, it is preferable to include at least one selected from concave portions formed in an annular shape and having a diameter equal to or smaller than the diameter of the center hole B.
[0058]
(Embodiment 1)
FIG. 2A shows a plan view and FIG. 2B shows a cross-sectional view of the optical disc 20 in the case where the first substrate has the above-described annular convex portion. FIG. 3A shows a plan view and FIG. 3B shows a cross-sectional view of the optical disc 30 in the case where the first substrate has convex portions of other shapes . Also, the first substrate, the first substrate 51 and 56 in the case and a recess of the projecting portion and the annular toric, shown in Figure 4 a cross-sectional view, respectively, (A) and (B). The first substrates 21 , 31 , 51 , and 56 are the same as the first substrate 11 except for the convex portions and the concave portions. That is, the one principal surface 21a, 31a , 51a, and 56a correspond to the one principal surface 11a. The optical disk 2 0 Contact and 3 0, respectively, is the same as the optical disc 10, except the first substrate 2 1 Contact and 3 1, a repetition of the same explanation is avoided.
[0059]
As shown in FIGS. 2A and 2B, the first substrate 21 of the optical disc 20 is formed in an annular shape so as to surround the center hole A on the one main surface 21a side where the signal area SA is formed. And the outer diameter L1 is provided with the convex part 22 equal to the diameter dB of the center hole B. By the convex portion 22, manufacture of the optical disk can be easily as described below. Moreover, it is preferable that the height (height from one main surface 21a) of the convex part 22 is 0.05 mm or more and 0.5 mm or less. Further, as shown in FIG. 2B, the height of the convex portion 22 is preferably larger than the sum of the thickness of the second substrate and the radiation curable resin 13 (even in the following convex portions). The same). As a result, when the optical disk 20 is superposed and held and stored, the reproduction surface does not directly touch another optical disk, and the reproduction surface is not damaged. Further, as shown in FIG. 2B, the convex portion 22 is formed so as to be in contact with the inner peripheral end of the second substrate 12 (the outer diameter L1 of the convex portion 22 is equal to the diameter dB of the center hole B). (It is the same for the following convex portions). Thereby, the eccentricity between the first substrate 11 and the second substrate 12 can be suppressed. Furthermore, since the center cone of the clamp and the motor turntable do not come into contact with the second substrate 12 during recording / reproduction, it is possible to cope with a decrease in strength due to the thinning of the second substrate 12, and the tilt increases. This can be suppressed.
[0060]
As shown in FIGS. 3A and 3B, the first substrate 31 of the optical disc 30 is formed in an annular shape so as to surround the center hole A on the one principal surface 31a side where the signal area SA is formed. In addition, a convex portion (step) 32 having an outer diameter L1 equal to the diameter dB of the center hole B is provided. The convex portion 32 in this case is formed up to the inner peripheral end of the first substrate 31.
[0061]
[0062]
Figure 4 (A), the first substrate 51, on one main surface 51a side of the signal area SA is formed, the central hole is formed in an annular shape to surround the A and outer diameter of the central hole B A convex portion 22 having a diameter equal to or smaller than the diameter of the convex portion 22 and a concave portion 42 arranged in an annular shape so as to surround the convex portion 22. Thereby , the effect of a convex part and a recessed part is acquired.
[0063]
Figure 4 (B), the first substrate 56, on one main surface 56a side of the signal area SA is formed, the central hole is formed in an annular shape to surround the A and outer diameter of the central hole B The convex part 32 which is below this diameter, and the recessed part 42 arrange | positioned annularly so that the convex part 32 may be enclosed. Thereby , the effect of a convex part and a recessed part is acquired.
[0064]
It should be noted that the optical disc 2 0 Contact and 3 0 the materials given above, it is needless to say that the same effects as the optical disc 10.
[0065]
In the present exemplary type condition it has been described an optical disk signal recording layer only on the first substrate is formed. However, in the optical disc of the present invention and the manufacturing method thereof, a signal recording layer may be formed on the second substrate ( the same applies hereinafter). For example, in the optical disk of the present invention and the manufacturing method thereof, a semitransparent signal recording layer may be formed on the second substrate, and both the first substrate and the second substrate may be provided with the signal recording layer. Further, a plurality of signal recording layers may be formed on the first substrate ( the same applies hereinafter). With these configurations, an optical disk having a two-layer structure can be obtained. In this case, the information recorded in both signal recording layers can be reproduced by the laser light incident from the second substrate side.
[0066]
( Optical disk manufacturing method )
Here , an example of the manufacturing method of the optical disk of the present invention will be described . Shows a manufacturing process in the case of producing an optical disk 10 described in Reference Example 5, the same applies to the case of manufacturing the optical disc 20 and 30 described above.
[0067]
Here will be described the manufacturing method, as shown in FIG. 5 (A), first and first substrate 11 having a center hole A includes a signal area SA on the main surface 11a, the center hole A central hole is also larger in diameter than the A light-transmitting second substrate 12 having B and thinner than the first substrate 11 is brought into close contact with the radiation curable resin 13a before curing so that the one principal surface 11a is on the inner side (step ( a)). At this time, the radiation curable resin 13a is disposed from at least the inner peripheral end 12s to the outer peripheral end 12t of the second substrate 12. Incidentally, the radiation-curable resin 13a is the inner peripheral end 11s to may be located in the first substrate 11, as described in Reference Example, it may be arranged so as not to clamp area C.
[0068]
The signal area SA of the first substrate 11 is formed by, for example, molding a resin by an injection molding method or a photopolymer method to form concave and convex pits, and then forming a reflective film (signal recording layer) made of Al having a film thickness of, for example, 50 nm. 14) can be formed by sputtering. Further, when the signal region SA is formed of a phase change film or a dye film, it can be formed by a sputtering method or a vapor deposition method. The first substrate 11 is, for example, a polycarbonate substrate having a thickness of 1.1 mm, a diameter of 120 mm, and a center hole diameter of 15 mm.
[0069]
The second substrate 12, For example other, is 90 [mu] m, an outer diameter of 120 mm, a center hole diameter is polycarbonate or acrylic substrates of 40mm thickness. The second substrate 12 can be formed by an injection molding method or a casting method. The thickness of the second substrate 12 is in the range of 0.03 mm to 0.3 mm.
[0070]
Thereafter, as shown in FIG. 5 (B), the radiation curable resin 13a is cured by irradiating the radiation curable resin 13a with radiation (such as ultraviolet rays and electron beams) to form a radiation curable resin 13 after curing. Then, the first substrate 11 and the second substrate 12 are bonded together (step (b)). Radiation may be irradiated continuously or in pulses (the same applies to the following manufacturing method ). In this way, the optical disk 10 can be manufactured.
[0071]
Hereinafter, in the first step, two methods will be described with respect to the method of bringing the first substrate 11 and the second substrate 12 into close contact with each other with the radiation curable resin 13a interposed therebetween.
[0072]
In the first method, the first substrate 11 and the second substrate 12 are integrated with the radiation curable resin 13a interposed therebetween, and then the integrated first substrate 11 and second substrate 12 are rotated. This is a method of stretching the radiation curable resin 13a. This method, an example of a step in FIG. In the step of FIG. 6, first, as shown in FIG. 6 (A), applying a radiation-curable resin 13a in an annular shape by the nozzle 71 on the first substrate 11. At this time, the first substrate 11 or the nozzle 71 is rotated at a low speed (20 rpm to 120 rpm). Further, in order to firmly adhere to the inner peripheral end 12s of the second substrate 12, the radiation curable resin 13a is placed on the first substrate 11 and the inner peripheral end 12s is disposed (for example, a radius of 20 mm to 20 mm). Apply to 25mm position).
[0073]
Next, as shown in FIG. 6 (B), the first substrate 11 and second substrate 12 is superimposed are opposed so as to concentrically. However, since the radiation-curable resin 13a in the clamping area C adheres influence on the tilt increases, as shown in FIG. 6 (C), the radiation 72, such as ultraviolet annularly on the outer peripheral side of the clamping area C irradiation Then, it is preferable to prevent the radiation curable resin 13a from entering the inner periphery any more. That is, the step (a) may include a step of curing at least a part of the radiation curable resin 13a disposed on the inner side of the signal area SA before rotating the first substrate 11 (the following first step). The same applies to the method 2). The radiation curable resin 13a may be applied on the second substrate 12.
[0074]
Thereafter, as shown in FIG. 6 (D), the two substrates are rotated at a high speed (1000 rpm to 10000 rpm) while the first substrate 11 and the second substrate 12 are overlapped, and the outer peripheral portion. The radiation curable resin 13a is diffused up to. As a result, it is difficult for bubbles to enter the bonded portion, and excess radiation curable resin 13 a is shaken off and discharged from between the first substrate 11 and the second substrate 12. In this way, step (a) can be performed.
[0075]
In the above process, in order to make the thickness of the radiation curable resin 13a uniform, the radiation curable resin depends on the number of rotations / rotation time of the substrate for resin diffusion and the thickness of the radiation curable resin 13a. It is preferred to select a viscosity of 13a. Generally, in the above method, the thickness of the radiation curable resin 13a tends to be thin on the inner peripheral side and thick on the outer peripheral side. In order to perform recording / reproduction under conditions such as a laser with a wavelength of 400 nm and an objective lens having an NA of 0.85, which are being studied for increasing the density of optical disks, the variation in film thickness of the radiation curable resin 13 is The central value (the sum of the thickness of the second substrate 12 and the thickness of the radiation curable resin 13, for example, 0.1 mm) is required to be within a range of about ± 3 μm.
[0076]
In the first method, Table 1 shows the relationship between the in-plane variation of the radiation curable resin 13 after curing and the viscosity of the radiation-curable resin 13a.
[0077]
[Table 1]
Figure 0003908478
[0078]
As apparent from Table 1, the viscosity of the radiation curable resin 13a by less 10 mPa · s or more 1500 mPa · s, 6 [mu] m or less variation in the thickness of the radiation curable resin 13 after curing, i.e. ± 3 [mu] m or less It can be.
[0079]
Table 2 shows the relationship between the viscosity of the radiation curable resin 13a and the tact time in the first method.
[0080]
[Table 2]
Figure 0003908478
[0081]
As is apparent from Table 2, in order to shorten the tact time, it is preferable that the viscosity of the radiation curable resin 13a is in the range of 10 mPa · s to 600 mPa · s.
[0082]
Next, the 2nd method for performing a 1st process is demonstrated. In the second method, after the radiation curable resin 13a is dropped onto the first substrate 11, the first substrate 11 is rotated to apply the radiation curable resin 13a onto the first substrate 11, and then In this method, the first substrate 11 and the second substrate 12 are adhered to each other with the radiation curable resin 13a interposed therebetween. This method, an example of a step in FIG. In the second method, first, as shown in FIG. 7 (A), applying a radiation-curable resin 13a in an annular shape by the nozzle 71 on the first substrate 11. This process is similar to the process described in FIG. 6 (A).
[0083]
Next, as shown in FIG. 7 (B), the first substrate 11 is rotated at a high speed (1000 rpm to 10000 rpm) to extend the radiation curable resin 13a to the outer periphery. At this time, as explained in the step of FIG. 6 (C), the laser light may be irradiated to the annular radiation curable resin 13a of the outer circumference side of the clamping area C.
[0084]
Thereafter, as shown in FIG. 7 (C), the first substrate 11 and second substrate 12 overlapped such that the concentric circles, brought into close contact. Thus, the said process (a) can be performed. In addition, the distribution of the radiation curable resin 13a can be made more uniform by applying an appropriate pressure uniformly at the time of superposition. At this time, care must be taken so that bubbles do not enter. To ensure that no air bubbles, as shown in FIG. 8, it is preferable to perform the step of adhering the substrate vacuum chamber 90 within, i.e. in a vacuum atmosphere.
[0085]
Table 3 shows the relationship between the viscosity of the radiation curable resin 13a and the in-plane variation of the radiation curable resin 13 after curing in the second method.
[0086]
[Table 3]
Figure 0003908478
[0087]
As is apparent from Table 3, by setting the viscosity of the radiation curable resin 13a to 10 mPa · s or more and 15000 mPa · s or less, variation in the film thickness of the radiation curable resin 13 after curing is 6 μm or less (± 3 μm or less). It can be.
[0088]
Table 4 shows the relationship between the viscosity of the radiation curable resin 13a and the tact time in the first method.
[0089]
[Table 4]
Figure 0003908478
[0090]
As is apparent from Table 4, in order to shorten the tact time, it is preferable that the viscosity of the radiation curable resin 13a is in the range of 10 mPa · s to 1000 mPa · s.
[0091]
As described above, according to the method of manufacturing the above SL of the optical disc, the optical disc can be easily manufactured. In the second method, a radiation curable resin may be applied to the second substrate and then adhered to the first substrate.
[0092]
In the above manufacturing method, instead of the first substrate 11, the first substrate 21 and 31 described in Embodiment 1 may be used 5 1 or 56. By using such a substrate, it is possible to prevent the radiation-curable resin 13a is applied to the O protrusion of annular remote peripheral side. In this case, since it is not necessary to perform the step of irradiating radiation in an annular shape, production is facilitated. Further, by making the outer diameter L1 of the convex portion the same as the diameter dB of the second substrate 12, it is possible to prevent eccentricity from occurring when the first substrate and the second substrate are bonded together.
[0093]
[0094]
[0095]
[0096]
[0097]
[0098]
[0099]
[0100]
[0101]
[0102]
[0103]
[0104]
[0105]
[0106]
[0107]
[0108]
[0109]
[0110]
[0111]
[0112]
[0113]
[0114]
[0115]
[0116]
[0117]
[0118]
[0119]
[0120]
[0121]
[0122]
[0123]
[0124]
[0125]
[0126]
[0127]
[0128]
[0129]
[0130]
[0131]
[0132]
[0133]
[0134]
[0135]
[0136]
Although the embodiments of the present invention have been described above by way of examples, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.
[0137]
【The invention's effect】
As described above, according to the optical disc of the present invention, an optical disc capable of high-density recording and easy to handle can be obtained.
[0138]
Further, according to the manufacturing method of the present invention can be easily produced capable of high-density recording optical disk.
[0139]
[Brief description of the drawings]
1A is a plan view and FIG. 1B is a cross-sectional view showing an example of an optical disc of a reference example .
Figure 2 shows an example with the optical disk of the present invention (A) a plan view and (B) is a cross-sectional view.
3A is a plan view and FIG. 3B is a sectional view showing another example of the optical disc of the present invention.
4A and 4B are cross-sectional views showing (A) an example and (B) another example of a substrate used in the optical disc of the present invention.
FIG. 5 is a process cross-sectional view illustrating an example of a method of manufacturing an optical disc according to the present invention .
FIG. 6 is a process cross-sectional view showing a part of the process of the optical disk manufacturing method of the present invention .
FIG. 7 is a process cross-sectional view showing a part of the process of the optical disk manufacturing method of the present invention.
8 is a view to cross-sectional view a part of a process for optical disc manufacturing method of the present invention.
[Explanation of symbols]
10,20,3 0 optical disk 11, 21, 31, 5 1, 5 6 1st board | substrate 11a, 12a, 21a, 31a , 5 1a, 56a One main surface 1 2 Second substrate 12s Inner peripheral edge 12t Outer peripheral edge 13, 13 a Radiation curable resin (adhesive member)
14 signal recording layers 22 and 32 convex portion 42 concave portion
71 nozzles
A , B Center hole C Clamp area SA Signal area dA, dB, L 1 diameter

Claims (8)

一主面に信号領域を備え中心孔Aを有する第1の基板と、前記第1の基板の前記一主面側に貼り合わされた、前記第1の基板よりも薄い透光性の第2の基板とを備える光ディスクであって、
前記第2の基板は前記中心孔Aよりも直径が大きい中心孔Bを有し、
前記第1の基板と前記第2の基板とが、前記第1の基板と前記第2の基板との間に配置された接着部材によって貼り合わされており、
前記第1の基板は、前記一主面側に、前記第中心孔Aを囲むように円環状に形成され且つ外径が前記中心孔Bの直径以下である凸部と、前記凸部を囲むように円環状に形成された凹部とを備え、
前記凸部の前記一主面からの高さが、前記第2の基板の厚さと前記接着部材の厚さとの和よりも大きいことを特徴とする光ディスク。
A first substrate having a signal region on one main surface and having a central hole A, and a light- transmitting second thin film bonded to the one main surface side of the first substrate and thinner than the first substrate An optical disc comprising a substrate,
The second substrate has a central hole B having a diameter larger than that of the central hole A,
The first substrate and the second substrate are bonded together by an adhesive member disposed between the first substrate and the second substrate ;
Said first substrate, on the one main surface side, and the convex portion and the outer diameter is formed in an annular shape so as to surround the first center hole A is less than the diameter of the central hole B, surrounds the protrusion And a concave portion formed in an annular shape ,
An optical disc, wherein a height of the convex portion from the one main surface is larger than a sum of a thickness of the second substrate and a thickness of the adhesive member.
前記凸部の前記一主面からの高さが、0.05mm以上0.5mm以下であることを特徴とする請求項1に記載の光ディスク。The optical disc according to claim 1 , wherein a height of the convex portion from the one principal surface is 0.05 mm or more and 0.5 mm or less. 前記接着部材は、少なくとも前記第2の基板の内周端から外周端にかけて配置されていることを特徴とする請求項1または2に記載の光ディスク。The optical disk according to claim 1, wherein the adhesive member is disposed at least from an inner peripheral end to an outer peripheral end of the second substrate. 前記第2の基板の厚さが、0.03mm以上0.3mm以下であることを特徴とする請求項1〜3のいずれか一項に記載の光ディスク。4. The optical disk according to claim 1, wherein the thickness of the second substrate is 0.03 mm or more and 0.3 mm or less. 前記第1の基板の前記信号領域に、複数の信号記録層が形成されていることを特徴とする請求項1〜4のいずれか一項に記載の光ディスク。5. The optical disc according to claim 1, wherein a plurality of signal recording layers are formed in the signal area of the first substrate. 6. 前記接着部材が放射線硬化性樹脂であることを特徴とする請求項1〜5のいずれか一項に記載の光ディスク。The optical disk according to claim 1, wherein the adhesive member is a radiation curable resin. 前記接着部材の平均厚さが、0.5μm以上30μm以下であることを特徴とする請求項1〜のいずれか項に記載の光ディスク。Optical disk according to any one of claims 1 to 6, the average thickness of the adhesive member, characterized in that at 0.5μm or 30μm or less. 情報の再生のために照射されるレーザの波長が、450nm以下であることを特徴とする請求項1〜7のいずれか一項に記載の光ディスク。The optical disk according to any one of claims 1 to 7, wherein a wavelength of a laser irradiated for reproducing information is 450 nm or less.
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