JP4632589B2 - Transparent touch panel with antireflection function and display device using the same - Google Patents

Description

【００２７】
となる。その結果、有効屈折率（ｎ_ef）の分布はｚのみの関数ｎ_ef（ｚ）となる（図４参照）。
【００２８】
よって、もしも、微細凹凸に於ける透明基材の凸部の断面積が、凹部に向かって連続的に増大する様な形状であれば（ＸＹ平面内に於ける）透明基材部分と空気部分との面積比がＺ軸方向に向かって連続的に変化する為、有効屈折率ｎ_ef（ｚ）はｚに付いての連続関数になる。
【００２９】
一方、屈折率ｎ₀の媒質から、屈折率ｎ₁の媒質に光が入射する場合を考える。今、簡単の為に、入射角θ＝０°（垂直入射）を考える。但し、入射角は入射面の法線に対する角度とする。
この場合、媒質界面での反射率Ｒは、偏光、及び入射角には依存せず、下記の〔式２〕となる。
【００３０】
【数２】

【００３１】
従って、（有効）屈折率のＺ方向への変化が連続関数であるということは、Ｚ方向（光の進行方向）に微小距離Δｚ隔てた２点、Ｚ＝ｚに於ける屈折率をｎ₀、Ｚ＝ｚ＋Δｚに於ける屈折率をｎ₁、としたときに、
【００３２】
Δｚ→０ ならば、 ｎ₁→ｎ₀
【００３３】
となり（連続関数の定義より）、よって、〔式２〕より、
【００３４】
Ｒ→０
【００３５】
となる。
【００３６】
なお、ここで、より厳密に言うと、物体中での光の波長は、真空中の波長をλ、物体の屈折率をｎとしたときに、λ／ｎとなり、λよりは一般に或る程度小となる。但し、物体が空気の場合の屈折率はｎ≒１の為、λ／ｎ≒λと考えて良い。但し、硝子、アクリル樹脂等の透明基材に使われる材料は、通常１．５前後の屈折率である為、屈折率ｎ_bの透明基材中の波長（λ／ｎ_b）は、０．７λ程度となる。この点を考慮すると、微細凹凸の部分に於いて、空気の側の部分（微細凹凸の凹部）について見れば、
【００３７】
Ｐ_MAX≦λ_MIN
【００３８】
の条件を満たすとき、屈折率平均化による反射率低減効果が期待出来る。但し、
【００３９】
λ_MIN／ｎ_b≦Ｐ_MAX≦λ_MIN
【００４０】
である場合は、透明基材の部分（微細凹凸の凸部）の寄与について見れば、屈折率平均化による反射率低減効果は、少なくとも完全には期待出来ないことになる。
しかし、それでも、空気部分に於ける寄与の為、全体としては反射防止効果を有する。
そして、
【００４１】
Ｐ_MAX≦λ_MIN／ｎ_b
【００４２】
の条件までも満たす場合は、空気部分、透明基材部分とも、周期Ｐ_MAXが、最短波長よりも小さいと言う条件が完全に満たされる為、屈折率平均化による反射防止効果は、より完全となる。
具体的には、λ_MINを可視光波長帯域の下限３８０ｎｍ、ｎ_bを仮に１．５とすれば、λ_MIN／ｎ_bは２５０ｎｍ、つまりＰ_MAXは２５０ｎｍ以下とすれば良い。
【００４３】
次に、微細凹凸の形状は、微細凹凸をその凹凸方向と直交する面（ＸＹ平面）で切断したと仮定したときの断面（水平断面）内に於ける透明基材の材料部分の断面積占有率が、該微細凹凸の最凸部から最凹部に行くに従って連続的に漸次増加して行き、最凹部に於いて１となる様な形状であれば、どんな形状でも良い。この為には、微細凹凸の山は少なくともその一部の側面が斜めの斜面を有するものとすれば良いが、下記する図５（Ｃ）の様に斜面と共に垂直側面がある形状の微細凹凸２でも良い。
【００４４】
例えば、個々の微細凹凸２の垂直断面形状は、図５（Ａ）の如き正弦波等の曲線のみによる波状の形状〔図２も参照〕、図５（Ｂ）及び図５（Ｃ）の如き三角形等の直線のみによる形状、或いは、図５（Ｄ）の如き三角形の最凸部が平坦面を成す形状である台形の形状、図５（Ｅ）の如き隣接する三角形間の最凹部が平坦面を成す形状等である。但し、図５（Ｄ）や図５（Ｅ）の如く、最凸部或いは最凹部に平坦面を有する形状では、最凸部或いは最凹部の平坦面の部分で、その平坦面の占める面積割合が大きい程、有効屈折率の変化がより大きく不連続となる。その点で性能的には劣るものとなる。しかし、この場合でも、微細凹凸の最凸部から最凹部に行くに従って有効屈折率を連続的に変化させることは出来る。従って、反射防止性能の点では、最凸部或いは最凹部の平坦面の面積割合は少ない程好ましい。
なお、水平断面内での透明基材の断面積占有率が、微細凹凸の最凹部に於いて１となる形状とは、図５（Ｅ）の如く最凹部に於いて不連続な形状、すなわち、２値（その内の片方の断面積占有率が１）を取る形状も含む。
有効屈折率ｎ_ef（ｚ）を空気中から透明基材中に向かうＺ方向の関数として、ｎ_aからｎ_bに連続的に変化する様にする為には、最凸部に於いて断面積占有率が０に収束する図５（Ｂ）或いは図５（Ｃ）の如き形状（すなわち、尖った形状）で且つ最凹部に於いて断面積占有率が連続的に１に収束する形状が好ましい。
【００４５】
次に、個々の微細凹凸の水平断面形状は、円形（例えば図２）、楕円形、三角形、四角形、長方形、其の他多角形等任意である。なお、水平断面形状は、微細凹凸の最凸部から最凹部の全てにわたって同じである必要は無い。従って、微細凹凸の立体形状は、例えば、水平断面形状が円形で垂直断面形状が正三角形の場合の微細凹凸の立体形状は円錐に、水平断面形状が円形で垂直断面形状が三角形の場合の微細凹凸の立体形状は斜円錐に、水平断面形状が台形で垂直断面形状が正三角形の場合の微細凹凸の立体形状は円錐台に、水平断面形状が四角形で垂直断面形状が三角形の場合の微細凹凸の立体形状は四角錐になる。
【００４６】
また、微細凹凸の、水平面内に於ける配置は、図２で例示した如く二次元的配置の他に、図６（Ａ）の斜視図で例示の直線溝状の微細凹凸２の如く、一次元的配置でも良く、どちらも効果は得られる。但し、一次元的配置の場合は、光の波の振幅方向との関係で、反射防止効果が得られる方向と得られない方向とが出る、異方性が発生する。従って、図２の斜視図や図６（Ｂ）及び（Ｃ）の平面図で例示の様な二次元的配置の方が、方向性が全く無い点で好ましい。
【００４７】
なお、個々の微細凹凸の立体形状は全て同一でも良いが、全て同一で無くても良い。また、個々の微細凹凸を二次元配置する場合に、周期は、個々の微細凹凸に於いて全て同一でも良いが、全て同一で無くても良い。
【００４８】
また、微細凹凸の高さＨは、可視光帯域での反射率を、２％（硝子の半分）以下に低減させることを目標とするならば、その最小高さＨ_MINが０．２λ_MAX以上、すなわち、
【００４９】
Ｈ_MIN≧０．２λ_MAX
【００５０】
また、可視光帯域での反射率を０．５％以下にまで低減させることを目標とするならば、
【００５１】
Ｈ_MIN≧０．４λ_MAX
【００５２】
とするのが好ましい。なお、ここで、λ_MAXは、可視光波長帯域の真空中に於ける最大波長である。微細凹凸の高さＨは、ゼロから高くなるに従って反射率が低下して行くが、上記不等号条件を満足させる高さまで達すると、有為な効果が得られる様になる。具体的には、例えば、発光スペクトルの最大波長が、λ_MAX＝６４０ｎｍの蛍光灯を用いたとすれば、Ｈ_MIN≧０．２λ_MAX＝１２８ｎｍとなる。すなわち、Ｈ_MINは１２８ｎｍ以上とすれば良い。また、スペクトルの最大波長がλ_MAX＝７８０ｎｍの太陽光線を考えるならば、Ｈ_MIN≧０．２λ_MAX＝１５６ｎｍ、すなわち、Ｈ_MINは１５６ｎｍ以上とすれば良い。また、最小高さＨ_MINと周期Ｐ_MAXとの関係では、最小高さＨ_MIN／周期Ｐ_MAXの比を、１／２〜４／１程度とする。
【００５３】
ここで、微小凹凸の具体的形状及び大きさを例示すれば、形状は垂直断面が正弦波状で水平断面が円形の円錐状の形状のものを多数、二次元的に規則的配置した集合体であり、周期期Ｐ_MAXが５０〜２５０ｎｍ、最小高さＨ_MINを前記周期Ｐ_MAXの１．５倍としたもの等がある。
【００５４】
ところで、以上の如き本発明特有の微細凹凸は、特開昭５０−７００４０号公報、或いはＵＳＰ４，０１３，４６５号公報にて、「放射に対する表面の反射率を減少させる方法」として開示された技術を、透明タッチパネルに応用したものである。但し、この様な微細凹凸を、外光反射防止の為に透明タッチパネルに適用すべく、外光が最初に当たる透明タッチパネルの表面に設けただけでは、実用性能上、満足できる性能が得られなかった。それは、極めて微細な凹凸であるが故に、入力時にペンや指が触れる事によって、傷、手垢等による汚れが付き易い表面では、微細凹凸形状が鈍ってしまい効果が長続きしないからである。そこで、本発明では、表側にでは無くあえて裏側に設けた構成とすれば、ペンや指入力時の傷や手垢等による汚れに対しても耐性が得られ、尚且つ相応の反射防止効果が得られることを見出した。また、透明タッチパネルの裏面に設けることにより、表示パネルと透明タッチパネルとの間の多重反射によるコントラスト低下防止効果に於いては、むしろ、表面に該微細凹凸を設けた場合よりも良好であることを見出し、本発明に至ったものである。
【００５５】
〔透明基材〕
先ず、透明タッチパネルに用いる最裏面を成す透明基材１としては、透明で強度があれば、用途次第では樹脂シートの様に可撓性を有するものでも良いが、通常は、入力時のペンや指による押圧力を効果的に受け止める為、下側に配置される表示パネルを該押圧力から保護する為等の点で、剛体のものが好ましくは使用される。特に、ＬＣＤの表示パネルと透明タッチパネルとを組合わせた表示装置とする場合には、上記押圧力がＬＣＤに加わると、ＬＣＤ内部の液晶が部分的に変移し、その部分での表示が乱れるので、透明基材には剛体のものを用いて、これを防ぐのが好ましい。また、本発明特有の微細凹凸の形状の耐久性の点でも、最裏面を成す透明基材としては、剛体のものが好ましい。
なお、本発明の透明タッチパネルの入力方式としては、抵抗膜方式、接触方式、静電容量方式、（磁）歪方式、電磁誘導方式、光学（赤外線）方式、超音波方式等、従来公知の透明性を確保できる方式のいずれの方式でも良く、従って、最裏面を成す透明基材１には、適用する方式に合せた物を使用すれば良い。
【００５６】
剛体で透明性及び強度を有する透明基材の素材としては、例えば、ソーダガラス、ホウ珪酸ガラス、石英ガラス等のガラス、ＰＬＺＴ〔＝Ｌａ添加ジルコン・チタン酸鉛。超音波方式で使われる。〕等の無機材料、或いは、ポリ（メタ）アクリル酸メチル、ポリ（メタ）アクリル酸エチル、（メタ）アクリル酸メチル−（メタ）アクリル酸ブチル共重合体等のアクリル樹脂〔但し、（メタ）アクリルとはアクリル、或いはメタクリルを意味する。〕、ポリカーボネート樹脂、ポリプロピレン、ポリメチルペンテン、環状オレフィン系高分子（代表的にはノルボルネン系樹脂等があるが、例えば、日本ゼオン株式会社製の製品名「ゼオノア」、ＪＳＲ株式会社製の「アートン」等がある）等のポリオレフィン系樹脂、ポリエチレンテレフタレート、ポリエチレンナフタレート等の熱可塑性ポリエステル樹脂、ポリアミド樹脂、ポリスチレン、アクリロニトリル−スチレン共重合体、ポリエーテルスルフォン、ポリスルフォン、セルロース系樹脂、塩化ビニル樹脂、ポリエーテルエーテルケトン、ポリウレタン等の熱可塑性樹脂等の有機高分子材料等が挙げられる。
【００５７】
上記の如き素材からなる透明基材の厚さは、剛性を確保する為には、通常は０．５〜２ｍｍ程度とする。
【００５８】
なお、表側にも透明基材１ａを積層する構成となる抵抗膜方式の透明タッチパネルでは、表側の透明基材１ａには、可撓性のものを使用する。この様な透明基材１ａとしては、上記した樹脂素材が使用できる。但し、厚さは、可撓性が得られる程度の厚さとする。従って、厚さは、可撓性を確保しつつ、表面強度も確保する為に、通常、０．０５〜０．５ｍｍ程度である。
【００５９】
微細凹凸２は透明基材１の一部を構成するものであるが、該微細凹凸２を含む透明基材１は、図１（Ｂ）に例示の如く、全て同一材質からなる連続の物体として構成する以外に、図７に例示の透明タッチパネル１０の如く、その透明基材１を、微細凹凸２を含む部分（基材凹凸部１Ｂ）と、微細凹凸を含まない部分（透明基材本体１Ａ）とからなる例えば２層が密着した構成等としても良い。
但し、その場合、基材凹凸部１Ｂと透明基材本体１Ａとは、極力屈折率差を０に近づける様に材料を選択する。そうしないと、両者の界面で光反射を生じるからである。
【００６０】
〔微細凹凸の形成方法〕
ここで、上記の如き微細凹凸２を形成する方法について、更に説明する。なお、本発明では、該形成方法は、次の述べる方法に限定されるものでない。
【００６１】
微細凹凸２は、透明基材とする既に有形の物、一つ一つに、後から直接形成する事も可能である。しかし実用上、工業製品として大量生産するには、いずれにしても、一旦、（賦形）型を作り、この型（マザー版）から、或いは更に該型から作製した複数の型（マスター版）を経て、微細凹凸を形成するのが、量産性、コスト等の点で好ましい。これらの型を作った後は、それを用いた各種複製技術によって、透明基材に微細凹凸を形成できる。なお、型による微細凹凸の形成段階では、透明基材とする既に有形の物となった透明基材に対して、微細凹凸を形成したり、或いは、有形の物として透明基材を造形すると同時に、微細凹凸を形成することができる。
【００６２】
そして、型等として、微細凹凸となる凹凸形状を最初に造形する方法としては、半導体分野等に於ける微細加工技術を流用できる。但し、半導体の場合は、凹凸形状はその側面が通常垂直面で良く、本発明の如く斜面にする必要は特に無いため、本発明では、斜面が形成できる様にして微細加工する。
【００６３】
上記の如き微細加工技術としては、電子線描画法を利用できる。この方法では、先ず、ガラス基板の上にレジスト層を形成した後、電子線描画法により該レジスト層を露光し現像してパターニングしてレジストパターン層とする。この後、腐蝕マスクに該レジストパターン層を利用してガラス基板をドライエッチング法等により腐蝕することで、ガラス基板に微細凹凸形状が形成される。この際、エッチング時にサイドエッチングさせて、斜面を形成する。また、ガラス基板腐蝕時の腐蝕マスクとしてはレジストパターン層自体を直接用いても良いが、斜面を有する深い凹凸形状を形成するには、好ましくは、ガラス基板上にクロム等による金属層を設けた後、レジスト膜を形成してレジストパターン層を得、前記金属層をこのレジストパターン層を利用して金属パターン層としてたものを、腐蝕マスクとして用いるのが良い。
【００６４】
また、レジスト膜へのパターン形成に際しては、電子線描画法の他に、レーザー描画法も利用できる。レーザ描画法では、ホログラム、回折格子等の作製等に利用されているレーザ干渉法が利用できる。回折格子の場合は、一次元的配置であるが、角度を変えて多重露光すれば、二次元配置も可能となる。但し、レーザ干渉法では、得られる微細凹凸は、通常規則的配置となるが、電子線描画法では、規則配置の他にも、不規則配置も可能である。また、レーザー描画法であるレーザー干渉法では、レーザービームの指向性の制限があり、広い面積で安定したパターニング条件を得ることが難しいが、電子線を用いる電子線描画法ではこの様な問題は解消できるという利点がある。
【００６５】
以上の様にして得られた型を、透明基材に対する微細凹凸の形成に直接用いても良いが、量産の場合、通常は、該型はマザー版として使用して、該マザー版から作製したマスター版を型として利用する。
なお、マスター版の作製は、公知の方法、例えば、マザー版にニッケル等の金属めっきを行って、めっき層を剥がし金属マスター版を作製する（電鋳法）。或いは、このマスター版にもう一度めっきして、再度作製したマスター版を型として使用する。なお、最終的に透明基材に微細凹凸を形成する型としては、板状、シート状、或いは円筒状のものがあり得る。
【００６６】
以上の如き、マスター版（或いはマザー版）を（賦形）型として用いて、透明基材に対して微細凹凸を形成（複製）する具体的な方法としては、例えば、熱プレス法（エンボス法）、射出成形法、２Ｐ法（Ｐｈｏｔｏ Ｐｏｌｙｍｅｒ法）等の公知の複製法、或いは、微細凹凸賦形シートのラミネート法を、透明基材の材質等に応じて適宜選択すれば良い。
【００６７】
これらのうち、既に有形の透明基材に対する、微細凹凸の形成方法は、熱プレス法（エンボス法）、２Ｐ法（Ｐｈｏｔｏ Ｐｏｌｙｍｅｒ法）、ゾルゲル法、微細凹凸賦形シートのラミネート法等が挙げられ。このうち、熱プレス法（エンボス法）は、透明基材が一般に熱可塑性樹脂等の塑性変形可能な状態を呈することができる樹脂等の材料からなる場合に適用される。一方、２Ｐ法（ＰｈｏｔｏＰｏｌｙｍｅｒ法）、ゾルゲル法、微細凹凸賦形シート（或いは板）のラミネート法は、透明基材がガラス等の無機材料からなる場合でも適用できる方法である。
【００６８】
なお、ゾルゲル法（特開平６−６４９０７号公報等参照）は、金属アルコキシド等と増粘剤としてポリエチレングリコール等を含む組成物を、塗工し、ゾルが軟らかいうちに型押しして凹凸を賦形して、その後に最終的な乾燥、熱処理を行って、無機質の塗膜として微細凹凸を形成する方法である。
また、微細凹凸賦形シート（或いは板）とは、樹脂のシート或いは板に、前述型を使用する等して微細凹凸を既に賦形しておいた物である。該樹脂には、透明基材の材料として列記した樹脂等が使用できる。該凹凸賦形シート（或いは板）は、接着剤や熱融着で、板材やシート材からなる透明基材に貼着する。
【００６９】
次に、透明基材自体の造形時に同時に形成する、微細凹凸の形成方法は、射出成形法の他、２Ｐ法（Ｐｈｏｔｏ Ｐｏｌｙｍｅｒ法）等が挙げられる。
射出成形法は、型面に微細凹凸形状を設けてなる射出成形型を用い、微細凹凸を射出成形法によって形成する。この方法によれば、樹脂を用いて、透明基材自体と微細凹凸とを同時に成形にて形成する事が出来るので、極めて量産性に優れた方法となる。射出成形型に、微細凹凸形成用の微細凹凸形状を設けるには、前述の如くして得たマスター版（或いはマザー版）を、型面に装着する等すれば良い。
また、ここでの２Ｐ法では、透明基材自体も微細凹凸の同時に造形してしまう方法となる。
【００７０】
また、透明基材自体の造形時に同時に形成する微細凹凸の形成方法としては、透明基材がガラスの場合でも、ガラスは加熱より塑性変形可能な状態を呈することができるので、熱プレス法を適用して、透明基材の造形と同時に微細凹凸を形成しても良い。
【００７１】
なお、以上述べた各種形成方法のうち、図１（Ｂ）の如く透明基材１と微細凹凸２とが一体となった構造のものは、熱プレス法（エンボス法）、射出成形法、２Ｐ法（Ｐｈｏｔｏ Ｐｏｌｙｍｅｒ法）等の場合に得られ、また、図７の如く透明基材１Ａ本体に、微細凹凸２を含む基材凹凸部１Ｂが積層された構造のものは、射出成形法（本体と凹凸部との２色成形法）、２Ｐ法（Ｐｈｏｔｏ Ｐｏｌｙｍｅｒ法）、ゾルゲル法、微細凹凸賦形シート（或いは板）のラミネート法等の場合に得られる。
【００７２】
〔その他の構成要素〕
本発明の透明タッチパネルは、最裏面を成す透明基材の裏面に本発明特有の微細凹凸を有する構成であれば良く、その他の部分は、従来公知の各種方式の透明タッチパネルの各種構成を採用することができる。
【００７３】
例えば、同じ反射防止機能として、従来公知の単層或いは多層構成の反射防止層を、透明基材の他の面に設けた構成でも良い。また、光拡散による防眩性（或いは反射防止）を付与する層を表面に設けても良い。また、透明基材の面には、該反射防止層の有無に拘らず、傷付き防止等の為に従来公知のハードコート層を設ても良い。なお、反射防止層はハードコート層の上に設けるのが効果的である。
【００７４】
例えば、図８の断面図は、抵抗膜方式で例示した図１（Ａ）の構成に対して、透明タッチパネル１０の表面側の面に、本発明とは異なる形式による反射防止機能を付与した構成の透明タッチパネル１０であり、最表面を成す透明基材１ａの表面には、ハードコート層５、多層膜等による反射防止層６がこの順に形成された構成を示す。
【００７５】
〔表示装置〕
本発明の表示装置は、上述の如き本発明の透明タッチパネルの裏側に、表示パネルを配置して成る構成の、表示装置である。なお、当然であるが、該表示装置では、透明タッチパネル裏面と表示パネル表面とは、接着層等で完全に密着させずに、間に空隙を設けた配置である。それは、密着させた場合には、特定の微細凹凸による本発明特有の反射防止効果の意味が殆ど無いからである。
【００７６】
なお、本発明の表示装置にあっては、単に表示機能のみを有する装置（例えば、ＬＣＤモニター、ＣＲＴモニター等）でも良いが、装置の機能の一部として表示機能を有する装置も該当する。例えば、後述する用途で述べる如く、ＰＤＡ乃至は携帯情報端末、カーナビゲーションシステム等である。
【００７７】
ここで、図９の要部断面図で上記の如き表示装置１００の一形態を例示する。
同図の表示装置１００は、例えば、ＰＤＡ乃至は携帯情報端末等の表示部分を中心とした配置を概念的に示す断面図である。同図の表示装置１００では、透明タッチパネル１０は、その最裏面を成す透明基材の裏面に微細凹凸を有し、この透明タッチパネル１０の裏側に間に空隙を空けて、ＬＣＤ等のフラットパネルディスプレイによる表示パネル３０が配置されている構造である。なお、表示パネル３０は、その透明タッチパネル１０と対面する表側面に、上述した本発明特有の微細凹凸２からなる反射防止機能を付与したものとしても良い。これによって、表示装置１００としての反射防止機能は更に向上する。
【００７８】
〔透明タッチパネルの用途〕
本発明による透明タッチパネルは、各種表示装置の表示部に於ける入力手段（透明タブレットも含む）として使用され得る。この様な入力機能付きの表示装置は、例えば、ＬＣＤ（液晶ディスプレイ）、ＥＬＤ（エレクトロルミネッセントディスプレイ）、ＰＤＰ（プラズマディスプレイ）等のＦＰＤ（フラットパネルディスプレイ）、或いは、ＣＲＴ等を表示パネルに用いた装置である。なかでも、自己発光型では無い為に、相対的に外光による表示性能の低下が起きやすいＬＣＤは、本発明による効果がより大きく得られる点で好適である。なお、本発明に於ける表示装置としては、文字盤上に指針を有する時計に代表される機械式のアナログメータ等の様な機械的手段で情報を表示するものも包含するものとする。
【００７９】
上記の様な入力機能付き表示装置を有する各種製品としては、例えば、電子手帳等のＰＤＡ乃至は携帯情報端末（機器）、或いは、カーナビゲーションシステム、ＰＯＳ（販売時点情報管理）端末、携帯型オーダー入力端末、ＡＴＭ（現金自動預金支払兼用機）、ファクシミリ、固定電話端末、携帯電話端末、デシタルカメラ、ビデオカメラ、パソコン、パソコン用ディスプレイ、テレビジョン受像機、テレビ用モニターディスプレイ、券売機、計測機器、電卓、電子楽器等の電子機器、複写機、ＥＣＲ（金銭登録機）等の事務機器、或いは、洗濯機、電子レンジ等の電気製品がある。
【００８０】
【実施例】
以下、実施例により本発明を更に詳述する。
【００８１】
〔実施例１〕
ガラス基板上にスピンコート法により感光性樹脂のレジスト層を形成し、レーザ干渉露光装置により、アルゴンイオンレーザーを５０°の角度で２方向から露光する操作を、基板の縦横を９０度回転させて２回行った。次いで、現像液で現像して、レジストパターン層を形成した。
【００８２】
次に、ドライエッチング法によりガラス基板の腐蝕を行って、所望の微細凹凸形状が形成されたガラス基板からなる型（マザー版）を作製した。このマザー版に、コンパクトディスクの製造ライン等で用いられているニッケル電鋳法によって、ニッケルからなる型（マスター版）を作製した。
【００８３】
そして、抵抗膜方式の透明タッチパネル用に、その最裏面を構成する透明基材１として、片面（表側面）に抵抗膜としてＩＴＯを形成済みの厚さ１ｍｍのガラス板の最裏面とする面に、２Ｐ法によって微細凹凸２を形成した。具体的には、該透明基材の裏側とする面にシランカップリング処理したのち、その表面上に、下記組成の紫外線硬化性樹脂をポッティングした（塗工量換算２ｇ／ｍ²）。
【００８４】
〔紫外線硬化性樹脂〕
テトラブロムビスフェノールＡ型エポキシアクリレート ‥‥‥ ３２質量部
２−フェニル−２−（４−アクリロイルオキシエトキシフェニル）プロパン
‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ １８質量部
２，４，６−トリブロモフェニルエトキシアクリレート ‥‥‥ ５０質量部
１−ヒドロキシシクロヘキシルフェニルケトン ‥‥‥‥‥‥‥ ３質量部
【００８５】
次に、透明基材上の上記樹脂塊の上から、前記の如くして作製したマスター版を押し付けて樹脂を板面に行き渡らせて圧着させたままの状態で、透明基材側から高圧水銀灯で紫外線を照射して樹脂を硬化させ、マスター版を剥がし、ガラス板からなる透明基材の裏面に所望の微細凹凸を形成した。
【００８６】
上記透明基材の裏面には、原子間力顕微鏡での観察により、高さＨ_MINが２００ｎｍ、周期Ｐ_MAXが３００ｍの、図２の如き形状が多数縦横に正方格子状に規則的に配列された微細凹凸が形成されていた。
【００８７】
上記透明基材について、反射率測定を行った。先ず、反射防止処理をしていない側の面に、黒いビニール粘着テープを貼り付け、分光光度計にて、反射防止処理面に対して、垂直法線から５°の入射角にて測定したところ、視感反射率で０．１％と低い値に到達した。なお、微細凹凸による反射防止は未処理とした透明基材について、同様に視感反射率を測定したところ、４％であった。
【００８８】
そして、上記反射防止処理を施した透明基材と、ＩＴＯ膜を形成済みの厚さ０．１８ｍｍのポリエチレンテレフタレートシートとを組合わせて、抵抗膜方式の透明タッチパネルとして組み立てた。この透明タッチパネルの（裏面から表面へ透過する）全光線透過率は、パネル裏面の反射防止処理未処理の場合の８３％に対して、８８％と向上した。
更に、この透明タッチパネルを、ＬＣＤの表示パネルの前面に配置する構造の表示装置として組み立てた。
【００８９】
そして、上記反射防止処理を施した透明タッチパネルを、ＬＣＤの表示パネルの前面に配置した構造の表示装置と、上記反射防止処理は未処理の透明タッチパネルを同じく前面に表示パネルの配置した表示装置とを、同一の表示画像の輝度、及び、同一の室内光源の表示部面上照度と室内光入射角に於いて、目視比較した。その結果、反射防止処理未処理の透明タッチパネルを組合わせた表示装置と比較して、本発明の透明タッチパネルを用いた表示装置の方が、各種光源の照度、角度を変えても常に、表示が明るく見え、表示画像のコントラストも鮮明で、表示の視認性が良好であることが確認された。
【００９０】
【発明の効果】
（１）本発明の表示装置の透明タッチパネルによれば、透明タッチパネル裏面に於ける光反射を減らすことができる。すなわち、表示の視認に影響する波長成分として、透明タッチパネルの外側から来る外光の透明タッチパネル表裏両面（及び方式によっては内部構成面）による全反射光のうち、裏面からの反射光が除去され得る為、反射光の全量を、その分低減できる。従って、外光反射による表示の視認性低下を改善できる。しかも、反射防止の為に設けた本発明特定の微細凹凸は裏面に有り、透明タッチパネルの表面（表側面）には露出させて無い為、微細凹凸であるが故の、ペンや指での押圧による摩耗、油汚れ（の凹部充填）等による反射防止効果の低下も起きない。
また、本発明の透明タッチパネルを用いて表示装置を構成するときに、透明タッチパネル裏側に配置する表示パネルからの表示光（観察光）に対する透明タッチパネル裏面での反射も防止されるので、表示のコントラストが低下し表示が白化するのも防止できる。従って、この点でも表示の視認性を向上できる。また、視認性を向上できる為、例えば、液晶パネルのバックライトやフロントライト、或いはＥＬパネル等の表示パネルの電力を減らして、省エネルギー化、省電力化にも貢献する。
【００９１】
（２）更に、微細凹凸の周期と透明基材の屈折率とを特定の関係とすれば、特定形状の微細凹凸による反射防止効果が、より完全に得られる。
【００９２】
（３）また、本発明の表示装置によれば、透明タッチパネルの効果である前記（１）或いは更に（２）の効果を享受できる。その結果、表示の視認性が向上し、また、表示装置の省エネルギー化、省電力化にも貢献する。
【図面の簡単な説明】
【図１】本発明の透明タッチパネルを概念的に示す断面図。
【図２】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その１）。
【図３】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その２）。
【図４】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その３）。
【図５】微細凹凸の（垂直）断面形状の幾つかを例示する断面図。
【図６】微細凹凸の水平面内での配置の幾つかを例示する断面図。
【図７】透明タッチパネルに於ける透明基材の別の一形態を例示する断面図。
【図８】透明タッチパネルの別の一形態を例示する断面図。
【図９】表示装置の或る一形態を、その表示部について概念的に例示する断面図。
【符号の説明】
１ （最裏面を成す）透明基材
１ａ （最表面を成す）透明基材
１Ａ 透明基材本体
１Ｂ 基材凹凸部
２ 微細凹凸
２ｔ （微細凹凸の）最凸部
３、３ａ 抵抗膜
４ スペーサ
５ ハードコート層
６ （微細凹凸によらない）反射防止層
１０ 透明タッチパネル
３０ 表示パネル
１００ 表示装置
ｎ 屈折率
ｎ_a 屈折率（空気）
ｎ_b 屈折率（透明基材）
ｎ₀ 屈折率
ｎ₁ 屈折率
ｎ_ef（Ｚ） 有効屈折率
Ｈ_MIN （微細凹凸の）最小高さ
Ｉ₀ 入射光
Ｉ_R 表裏両面の反射光
Ｉ_Rsurf 表面の反射光
Ｉ_Rrear 裏面の反射光
Ｐ_MAX （微細凹凸の最凸部に於ける）周期
Ｒ 反射率
λ_MIN 最小波長
λ_MAX 最大波長[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transparent touch panel used in a display unit of various electronic devices such as a PDA or a portable information terminal (device), a car navigation system, and a display device using the same.
[0002]
[Prior art]
Currently, among various electronic devices having a display unit using a liquid crystal display (LCD) or the like as a display panel, for example, PDA (Personal Digital Assistants) or portable information terminals, car navigation systems, POS (sales point information management) Terminals, ATMs (automatic cash deposit / payment machines) and the like have a structure in which a transparent touch panel is arranged on the front surface of the display panel to form a display unit with an input function.
[0003]
[Problems to be solved by the invention]
By the way, as a transparent touch panel, there are conventionally known various types such as a resistive film method, a contact method, a capacitance method, a (magnetism) strain method, an electromagnetic induction method, an optical (infrared) method, an ultrasonic method, and the like. However, in any method, due to the arrangement on the front surface of the display panel, a certain amount of external light reflection is unavoidable on the transparent touch panel, which reduces the display visibility. Or the use efficiency of light from the display panel is reduced. Among them, the transparent touch panel of the resistive film type in which the transparent base material has two or more layers with a gap and the reflective surface increases correspondingly has a great influence on the visibility of reflected light.
[0004]
Therefore, for example, an antireflection layer composed of a single layer or a multilayer film of a low refractive index layer and a high refractive index layer is provided by a method such as vapor deposition, sputtering, or coating, or the reflective surface is treated with a satin finish. And the like (see Japanese Patent Application Laid-Open No. 2000-241794) have been developed. However, the antireflection film by vapor deposition, sputtering, etc. needs to form a thin film with a controlled refractive index by one or many batch processes, so there is a problem in product stability, yield rate, etc. Is low. Further, the satin treatment has a problem that the light use efficiency cannot be increased in terms of diffusing light.
[0005]
That is, an object of the present invention is to reduce reflection of light on a transparent touch panel, improve display visibility, and increase use efficiency of display light. It is another object of the present invention to provide a display device using such a transparent touch panel with an antireflection function.
[0006]
[Means for Solving the Problems]
Therefore, in order to solve the above problems, the transparent touch panel according to the present invention is provided on the back surface of the transparent base material forming the back surface, and in the transparent touch panel having an antireflection function, the antireflection function is provided on the back surface of the transparent base material. Anti-reflective fine irregularities are formed, and the fine irregularities have a minimum wavelength λ in a vacuum in the wavelength band of visible light._MIN, The period at the most convex part of the fine irregularities is P_MAXP_MAX≦ λ_MINAnd the cross-sectional area occupancy of the material portion of the transparent substrate in the cross section when the fine unevenness is assumed to be cut by a plane orthogonal to the unevenness direction is the most convex of the fine unevenness. It is a concavo-convex shape that gradually increases gradually from the part to the most concave part and becomes 1 in the most concave part.In other words, the fine irregularities are formed using a mold.The configuration.
[0007]
By adopting such a configuration, the refractive index change between the transparent touch panel and the air on the back surface of the transparent touch panel can be changed continuously and gradually, not discontinuously and rapidly. Since the reflection of light at the material interface is caused by a sudden change in refractive index, the change in the refractive index on the back surface of the transparent touch panel is changed gradually and gradually. Light reflection on the back of the touch panel can be reduced. That is, as the wavelength component that affects the visual recognition of the display, both the front and back surfaces of the transparent touch panel (to the viewer side) of external light (more strictly, wavelength light in the visible light region of the external light) coming from the outside of the transparent touch panel (and Depending on the method, the reflection on the back surface of the transparent touch panel can be removed among the reflections due to the internal configuration surface), so that the total amount of reflected light from the transparent touch panel can be reduced accordingly. Accordingly, it is possible to improve the visibility reduction of the display due to reflection of external light. In addition, the specific fine irregularities are present on the back surface of the touch panel, and are not exposed on the surface (front side) of the transparent touch panel. The reduction of the antireflection effect due to the filling of the concave portions of the film does not occur.
In addition, when a display device is configured using this transparent touch panel, reflection of the display light (observation light) from the display panel arranged on the back side of the transparent touch panel on the back surface of the transparent touch panel is also prevented, and light on the transparent touch panel is prevented. Since the transmittance is also increased, it is possible to prevent the display light from being reflected multiple times between the back surface of the transparent touch panel and the display panel surface, thereby reducing the display contrast and whitening the display. Therefore, the visibility of display can be improved. In addition, since the visibility is improved, for example, the power of a display panel such as a backlight of a liquid crystal panel, a front light, or an EL panel is reduced, thereby contributing to energy saving and power saving of an electronic device.
[0008]
In the transparent touch panel of the present invention, the refractive index of the transparent substrate is further set to n._bAnd when
P_MAX≦ λ_MIN/ N_b
The configuration has the following relationship.
[0009]
By having such a configuration, P_MAXAnd λ_MINThe definition of the relationship with the above also takes into consideration the wavelength size in the transparent base material that is shorter than in vacuum, and the antireflection effect due to specific fine irregularities can be obtained more completely.
[0010]
The display device of the present invention has a configuration in which a display panel is further arranged on the back side of the transparent touch panel with an antireflection function of any one of the present invention.
[0011]
By setting it as the display apparatus of such a structure, the effect of the transparent touch panel mentioned above can be enjoyed. As a result, the visibility of the display is improved, and it contributes to energy saving and power saving of the display device.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0013]
〔Overview〕
First, FIG. 1A is a sectional view conceptually showing a transparent touch panel 10 according to the present invention as a form of a resistive film system which is also a representative system. In the case of a resistive film type transparent touch panel, the transparent substrate 1 on the front side is used in combination with the transparent substrate 1 on the back side that is on the display panel side, that is, on the outermost surface. Resistive films 3 and 3a are formed on the inner surfaces of 1 and 1a, respectively, and a space is maintained between the resistive film 3 and the resistive film 3a by a spacer 4 formed in a dot shape. And, in the transparent touch panel 10 of the present invention, as shown in the figure, for the purpose of preventing reflection, specific fine irregularities 2 are formed on the back surface (lower side of the drawing) of the transparent base material 1 on the back side which is the display panel side. In other words, at least the back surface is provided with an antireflection function.
[0014]
Although FIG. 1A shows a resistance film method, the transparent touch panel of the present invention may be any method such as a resistance film method, an ultrasonic method, a capacitance method, or an electromagnetic induction method. . In the resistive film system, since the transparent base material has a structure in which two sheets are stacked, the side on which the fine unevenness of the present invention is provided is specified as the one that forms the outermost surface. In this case, the single transparent substrate itself is the transparent substrate that forms the outermost surface.
[0015]
FIG. 1B is a cross-sectional view conceptually showing only the portion of the transparent substrate 1 in the resistive film system illustrated in FIG. It is a figure which shows the structure by which the said specific fine unevenness | corrugation 2 is formed in the back surface side of the transparent base material 1 to comprise.
[0016]
The fine unevenness 2 unique to the present invention is a conventionally known antireflection treatment that scatters (diffuse reflection) light using a mat surface (matte) formed by unevenness having a size equal to or greater than the light wavelength (JP 2000- Unlike the anti-glare treatment (see, for example, Japanese Patent Application Laid-Open No. 2000-241794, etc.), the irregularities have a specific shape with a size equal to or smaller than the wavelength of visible light. By such fine irregularities, the sudden and discontinuous refractive index change between the transparent substrate and the outside (air) on the fine irregularity forming surface is changed into a continuous and gradually changing refractive index change. Is possible. Since light reflection is a phenomenon caused by a sudden and rapid change in refractive index at the material interface, a light reflection preventing effect can be obtained by changing the refractive index so as to change spatially continuously. . In addition, since the fine irregularities are formed on the back surface of the transparent base material that forms the backmost surface, the fine irregularities can be formed without any contact with the pen or fingers during use, due to wear from these presses, oil stains (filling of the depressions), etc. It is not dull and the antireflection effect is not lowered.
[0017]
As a result of the above, in FIG. 1B, the incident light I incident on the transparent base material 1 constituting the outermost surface from the front (side) surface above the drawing.₀Is partially reflected on the surface of the transparent substrate 1, and the reflected light I on the surface_RsurfAnd part of the light reaching the back surface is reflected light I on the back surface._RrearThus, the sum of both reflected lights is reflected on the observer side by reflected light I._RIn the present invention, the reflected light on the back surface is I_RrearIs removed (or reduced) so that the reflected light I_RThe total amount of light can be reduced accordingly, and the reflected light I on the back surface_RrearIs zero, the surface reflected light I_RsurfIt becomes only.
[0018]
In addition, it is possible to provide fine irregularities on the surface side of the transparent touch panel as well as the back surface for the purpose of preventing reflection of the surface on the inner surface of the two-layer transparent base material. When the unevenness is provided, the uneven shape is easily damaged due to scratches or dirt by a pen or a finger, or the recesses of the unevenness are easily filled. Therefore, in the transparent touch panel 10 of the present invention, the specific fine unevenness is not provided on the surface. . However, if necessary, the surface may be uneven, or may have unevenness as a mat surface (anti-glare treatment surface) for anti-glare purposes. Further, a conventionally known antireflection layer such as a low refractive index layer or a hard coat layer may be provided on the surface of the transparent touch panel.
In addition, in a transparent touch panel composed of two or more transparent substrates such as a resistance film type, these layers are inner surfaces (the surface of the transparent substrate 1 constituting the outermost surface, that is, the inner surface. It may be on the back surface of the transparent substrate 1a forming the surface, that is, the inner back surface.
[0019]
In addition, when the fine unevenness | corrugation of this invention is provided in the inner surface of the transparent base material 1 or 1a, since the transparent base material 1 and the transparent base material 1a approach at the time of input, and a pressing force is added to the fine unevenness | corrugation of an inner surface, Is preferably not provided in terms of shape durability.
As described above, the transparent base material that forms the outermost surface on which the fine irregularities unique to the present invention are formed is not a flexible body that deforms by the pressing force at the time of input, but is made of a rigid body. This is preferable.
[0020]
In the present invention, the surface refers to a side where a pen or finger is touched for input, and the display device refers to a surface on the side where the display is observed, that is, a surface outside the display device. Moreover, a back surface means the surface by the side of a display panel as a transparent touch panel, ie, the surface of the internal direction of a display apparatus. Speaking of these as transparent substrates, the front surface refers to the surface facing the input side by touching a pen or finger, and the back surface refers to the surface facing the display panel side.
[0021]
In addition, the formation method of the fine unevenness 2 in the present invention is not particularly limited. For example, the uneven shape is duplicated by using a mold produced using an electron beam drawing method or a laser drawing method. By doing so, mass production of a transparent touch panel (a transparent base material with an antireflection function used for) becomes easy. In the case of a resin-made transparent base material, replication may be performed by a hot press method, an injection molding method, a 2P method, a laminating method of a fine uneven shape forming sheet, etc., and in the case of a transparent base material made of glass or the like. May be based on the 2P method, the lamination method of the fine unevenness shaping sheet, the sol-gel method, or the like.
[0022]
[Fine unevenness]
Next, FIGS. 2 to 4 are conceptual diagrams for conceptually explaining the refractive index distribution obtained by the fine unevenness 2. First, in FIG. 2, the transparent base material 1 occupies a space of a portion where Z ≦ 0, and on the surface of the transparent base material, that is, the XY plane at Z = 0, a large number of Z-axis directions are uneven directions. The state where the fine unevenness | corrugation 2 is arrange | positioned is shown. 2 to 4, for the convenience of explanation, the back surface side of the transparent base material is on the upper side of the drawing, contrary to FIG. 1.
[0023]
In the present invention, the fine unevenness 2 is set to P as the period at the most convex portion 2t._MAXWhen this P_MAXIs the minimum wavelength in vacuum in the visible light wavelength band._MINBecause of the following, for the light reaching the surface with fine irregularities, even if there is a spatial distribution in the refractive index of the medium (transparent substrate and air), it is a distribution with a size below the wavelength of interest. Therefore, the distribution does not act directly on the light, but acts as an average. Therefore, if the distribution is such that the averaged refractive index (effective refractive index) changes continuously as the light travels, reflection of light can be prevented.
In the present invention, the period P at the most convex part 2t._MAXIs the maximum distance between the most convex portions 2t of the adjacent fine irregularities 2, and each fine irregularity is regularly arranged and has periodicity (the distance between adjacent fine irregularities is the same). ) Structure, but may have a structure with no periodicity (the distance between adjacent fine irregularities is not uniform).
[0024]
In FIG. 2, as an orthogonal coordinate system, the Z axis is taken in the normal direction set up on the envelope surface of the transparent substrate, and the X axis and the Y axis are taken in a plane perpendicular to the Z axis. And now, light enters the transparent base material from the front surface side, proceeds inside the transparent base material, and proceeds in the vicinity of the back surface of the transparent base material in the positive direction of the Z axis. Is present at z.
[0025]
Then, for the light at Z = z here, the refractive index of the medium is strictly the XY plane (cross section) orthogonal to the Z axis at Z = z because the transparent substrate has specific fine irregularities. : Horizontal cross section), it appears to have a distribution f (x, y, z). That is, in the XY plane, the cross-sectional portion of the transparent substrate 1 has a refractive index n._b(About 1.5), the other part, specifically the part of air a is the refractive index n_a(= About 1.0) (see FIG. 3).
However, in practice, for light, its wavelength (if the wavelength of light related to visual recognition of the display device has a distribution, the minimum wavelength λ of the wavelength band)_MINAs a result, the effective refractive index of the averaged result is the refractive index distribution f (x, y) in the XY plane. , Z) integrated in the XY plane,
[0026]
[Expression 1]

[0027]
It becomes. As a result, the effective refractive index (n_ef) Distribution is a function n of z only_ef(Z) (see FIG. 4).
[0028]
Therefore, if the cross-sectional area of the convex portion of the transparent base material in the fine unevenness is a shape that continuously increases toward the concave portion (in the XY plane), the transparent base portion and the air portion The effective refractive index n is continuously changed in the Z-axis direction._ef(Z) is a continuous function for z.
[0029]
On the other hand, refractive index n₀From the medium of the refractive index n₁Consider the case where light is incident on the medium. For the sake of simplicity, consider an incident angle θ = 0 ° (normal incidence). However, the incident angle is an angle with respect to the normal of the incident surface.
In this case, the reflectance R at the medium interface does not depend on the polarization and the incident angle, and is expressed by the following [Equation 2].
[0030]
[Expression 2]

[0031]
Therefore, the fact that the (effective) change in the refractive index in the Z direction is a continuous function means that the refractive index at Z = z at two points separated by a small distance Δz in the Z direction (light traveling direction) is n.₀, The refractive index at Z = z + Δz is n₁, And when
[0032]
If Δz → 0, n₁→ n₀
[0033]
(From the definition of the continuous function)
[0034]
R → 0
[0035]
It becomes.
[0036]
Strictly speaking, the wavelength of light in the object is λ / n where λ is the wavelength in vacuum and n is the refractive index of the object. Become small. However, since the refractive index when the object is air is n≈1, it can be considered that λ / n≈λ. However, since the materials used for transparent substrates such as glass and acrylic resin usually have a refractive index of around 1.5, the refractive index n_bWavelength in transparent substrate (λ / n_b) Is about 0.7λ. Considering this point, in the fine uneven part, if you look at the air side part (fine concave part),
[0037]
P_MAX≦ λ_MIN
[0038]
When the above condition is satisfied, the effect of reducing the reflectance by averaging the refractive index can be expected. However,
[0039]
λ_MIN/ N_b≦ P_MAX≦ λ_MIN
[0040]
In this case, if the contribution of the transparent base material portion (protrusions of fine irregularities) is seen, the reflectance reduction effect due to the refractive index averaging cannot be expected at least completely.
However, it still has an anti-reflection effect as a whole because of its contribution in the air portion.
And
[0041]
P_MAX≦ λ_MIN/ N_b
[0042]
If both conditions are satisfied, both the air portion and the transparent substrate portion have a period P_MAXHowever, since the condition that the wavelength is smaller than the shortest wavelength is completely satisfied, the antireflection effect by the refractive index averaging becomes more complete.
Specifically, λ_MINThe lower limit of the visible light wavelength band is 380 nm, n_bIs 1.5, λ_MIN/ N_bIs 250 nm, ie P_MAXMay be 250 nm or less.
[0043]
Next, the shape of the fine irregularities occupies the cross-sectional area occupied by the material portion of the transparent substrate in the cross section (horizontal cross section) when it is assumed that the fine irregularities are cut by a plane (XY plane) perpendicular to the irregular direction. Any shape may be used as long as the rate gradually increases gradually from the most convex portion of the fine unevenness to the most concave portion and becomes 1 in the most concave portion. For this purpose, at least a part of the ridges of the fine irregularities may have an inclined slope. However, as shown in FIG. But it ’s good.
[0044]
For example, the vertical cross-sectional shape of each fine unevenness 2 is a wave-like shape only by a curve such as a sine wave as shown in FIG. 5 (A) (see also FIG. 2), as shown in FIG. 5 (B) and FIG. 5 (C). A shape formed only by a straight line such as a triangle, or a trapezoidal shape in which the most convex part of the triangle forms a flat surface as shown in FIG. 5D, and the most concave part between adjacent triangles as shown in FIG. The shape of the surface. However, as shown in FIG. 5D and FIG. 5E, in the shape having a flat surface in the most convex portion or the most concave portion, the area ratio occupied by the flat surface in the flat surface portion of the most convex portion or the most concave portion. The larger the is, the greater the change in effective refractive index becomes discontinuous. In that respect, performance is inferior. However, even in this case, the effective refractive index can be continuously changed from the most convex part to the most concave part of the fine irregularities. Therefore, in terms of antireflection performance, the smaller the area ratio of the flat surface of the most convex part or the most concave part, the better.
Note that the shape in which the cross-sectional area occupation ratio of the transparent base material in the horizontal cross section is 1 in the most concave portion of the fine unevenness is a discontinuous shape in the most concave portion as shown in FIG. It also includes a shape that takes a binary value (one of which has a cross-sectional area occupation ratio of 1).
Effective refractive index n_ef(Z) as a function of the Z direction from the air into the transparent substrate, n_aTo n_bIn order to change continuously, the cross-sectional area occupancy rate converges to 0 at the most convex part, as shown in FIG. 5B or FIG. 5C (that is, a sharp shape). In addition, a shape in which the cross-sectional area occupation ratio continuously converges to 1 in the most concave portion is preferable.
[0045]
Next, the horizontal sectional shape of each fine unevenness is arbitrary such as a circle (for example, FIG. 2), an ellipse, a triangle, a quadrangle, a rectangle, and other polygons. The horizontal cross-sectional shape does not have to be the same from the most convex part to the most concave part of the fine irregularities. Therefore, the three-dimensional shape of the fine unevenness is, for example, a fine three-dimensional shape of the fine unevenness when the horizontal cross-sectional shape is circular and the vertical cross-sectional shape is equilateral triangle, and the fine shape when the horizontal cross-sectional shape is circular and the vertical cross-sectional shape is triangular. The three-dimensional shape of the unevenness is an oblique cone, the three-dimensional shape of the fine unevenness when the horizontal cross-sectional shape is trapezoid and the vertical cross-sectional shape is an equilateral triangle, the three-dimensional shape of the fine unevenness is the truncated cone, and the fine unevenness when the horizontal cross-sectional shape is a quadrangle The three-dimensional shape becomes a quadrangular pyramid.
[0046]
Further, the arrangement of the fine irregularities in the horizontal plane is not limited to the two-dimensional arrangement as illustrated in FIG. 2, but also as the linear groove-shaped fine irregularities 2 illustrated in the perspective view of FIG. The original arrangement may be used, and both are effective. However, in the case of the one-dimensional arrangement, anisotropy occurs in which a direction in which an antireflection effect is obtained and a direction in which the antireflection effect is not obtained are generated in relation to the amplitude direction of the light wave. Accordingly, the two-dimensional arrangement illustrated in the perspective view of FIG. 2 and the plan views of FIGS. 6B and 6C is preferable in that there is no directivity.
[0047]
In addition, although all the solid shapes of each fine unevenness | corrugation may be the same, it does not need to be all the same. In addition, when the individual fine irregularities are arranged two-dimensionally, the period may be the same for each fine irregularity, or not all.
[0048]
The height H of the fine unevenness is the minimum height H if the goal is to reduce the reflectance in the visible light band to 2% (half the glass) or less._MINIs 0.2λ_MAXThat is,
[0049]
H_MIN≧ 0.2λ_MAX
[0050]
If the goal is to reduce the reflectance in the visible light band to 0.5% or less,
[0051]
H_MIN≧ 0.4λ_MAX
[0052]
Is preferable. Where λ_MAXIs the maximum wavelength in a vacuum in the visible light wavelength band. Although the reflectance decreases as the height H of the fine irregularities increases from zero, a significant effect can be obtained when the height reaches a height that satisfies the above inequality condition. Specifically, for example, the maximum wavelength of the emission spectrum is λ_MAX= If a fluorescent lamp of 640 nm is used, H_MIN≧ 0.2λ_MAX= 128 nm. That is, H_MINMay be 128 nm or more. The maximum wavelength of the spectrum is λ_MAX= If you consider 780nm sunlight, H_MIN≧ 0.2λ_MAX= 156 nm, ie H_MINMay be 156 nm or more. Minimum height H_MINAnd period P_MAXThe minimum height H_MIN/ Cycle P_MAXThe ratio is about 1/2 to 4/1.
[0053]
Here, as an example of the specific shape and size of the micro unevenness, the shape is an aggregate in which a plurality of conical shapes having a sine wave vertical section and a circular horizontal section are regularly arranged two-dimensionally. Yes, period P_MAX50-250nm, minimum height H_MINThe period P_MAXThere are some that are 1.5 times larger.
[0054]
By the way, the fine irregularities peculiar to the present invention as described above are disclosed in Japanese Patent Application Laid-Open No. 50-70040 or US Pat. No. 4,013,465 as “a method for reducing the reflectance of a surface with respect to radiation”. Is applied to a transparent touch panel. However, in order to apply such fine irregularities to the transparent touch panel to prevent reflection of external light, it was not possible to obtain satisfactory performance in terms of practical performance simply by providing it on the surface of the transparent touch panel to which external light first hits. . The reason for this is that since the surface is very fine unevenness, the fine uneven shape is dulled on the surface that is easily soiled by scratches, dirt, etc. when touched by a pen or a finger during input, and the effect does not last long. Therefore, in the present invention, if the configuration is provided on the back side, not on the front side, it is possible to obtain resistance against dirt due to scratches and dirt when pens or fingers are input, and a corresponding antireflection effect is obtained. I found out that In addition, by providing on the back surface of the transparent touch panel, the effect of preventing the reduction in contrast due to multiple reflection between the display panel and the transparent touch panel is rather better than the case where the fine unevenness is provided on the surface. This is the headline and the present invention.
[0055]
(Transparent substrate)
First, as the transparent base material 1 that forms the outermost surface used for the transparent touch panel, as long as it is transparent and strong, it may be flexible like a resin sheet depending on the application. In order to effectively receive the pressing force by the finger, a rigid one is preferably used in terms of protecting the display panel disposed below from the pressing force. In particular, in the case of a display device that combines an LCD display panel and a transparent touch panel, when the above pressing force is applied to the LCD, the liquid crystal inside the LCD partially shifts and the display at that portion is disturbed. It is preferable to prevent this by using a rigid substrate for the transparent substrate. Also, from the viewpoint of durability of the shape of fine irregularities unique to the present invention, the transparent base material forming the outermost surface is preferably a rigid body.
In addition, as an input method of the transparent touch panel of the present invention, a conventionally known transparent method such as a resistive film method, a contact method, a capacitance method, a (magnetism) strain method, an electromagnetic induction method, an optical (infrared) method, an ultrasonic method, etc. Any of the methods that can secure the properties may be used, and therefore, the transparent substrate 1 that forms the outermost surface may be a material that matches the method to be applied.
[0056]
As a material of a transparent base material that is rigid and has transparency and strength, for example, glass such as soda glass, borosilicate glass, quartz glass, PLZT [= La-added zircon / lead titanate. Used in the ultrasonic method. ] Inorganic materials such as poly (meth) acrylate, poly (meth) ethyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, etc. (however, (meth) Acrylic means acrylic or methacrylic. ], Polycarbonate resin, polypropylene, polymethylpentene, cyclic olefin polymer (typically norbornene resin, etc., for example, product name “ZEONOR” manufactured by ZEON CORPORATION, “ARTON” manufactured by JSR Corporation Etc.), thermoplastic polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resin, polystyrene, acrylonitrile-styrene copolymer, polyether sulfone, polysulfone, cellulose resin, vinyl chloride resin And organic polymer materials such as thermoplastic resins such as polyetheretherketone and polyurethane.
[0057]
In order to ensure rigidity, the thickness of the transparent substrate made of the material as described above is usually about 0.5 to 2 mm.
[0058]
In the resistive touch panel transparent touch panel in which the transparent substrate 1a is laminated on the front side, a flexible material is used for the transparent substrate 1a on the front side. The resin material described above can be used as such a transparent substrate 1a. However, the thickness is set to such a degree that flexibility can be obtained. Therefore, the thickness is usually about 0.05 to 0.5 mm in order to ensure flexibility while ensuring surface strength.
[0059]
Although the fine irregularities 2 constitute a part of the transparent substrate 1, the transparent substrate 1 including the fine irregularities 2 is a continuous object made of the same material as illustrated in FIG. In addition to the configuration, like the transparent touch panel 10 illustrated in FIG. 7, the transparent substrate 1 is divided into a portion including the fine irregularities 2 (substrate irregularity portion 1B) and a portion not including the fine irregularities (transparent substrate main body 1A). For example, a structure in which two layers are in close contact with each other.
However, in that case, the material of the substrate uneven portion 1B and the transparent substrate body 1A is selected so that the refractive index difference is as close to 0 as possible. Otherwise, light reflection occurs at the interface between the two.
[0060]
[Method for forming fine irregularities]
Here, the method for forming the fine irregularities 2 as described above will be further described. In the present invention, the formation method is not limited to the following method.
[0061]
The fine irregularities 2 can be directly formed later on each of the already tangible objects as transparent substrates. However, for practical mass production as an industrial product, in any case, once a (shaped) mold is made, this mold (mother version) or a plurality of molds (master version) made from the mold It is preferable in terms of mass productivity, cost, and the like to form fine irregularities through the above. After these molds are made, fine irregularities can be formed on the transparent substrate by various replication techniques using the molds. In addition, at the formation stage of the fine irregularities by the mold, the fine irregularities are formed on the transparent substrate that has already become a tangible material as the transparent substrate, or at the same time the transparent substrate is shaped as a tangible object Fine irregularities can be formed.
[0062]
Then, as a method for first forming a concave-convex shape as a mold or the like, a fine processing technique in the semiconductor field or the like can be used. However, in the case of a semiconductor, the side surface of the concavo-convex shape may be a normal vertical surface, and it is not particularly necessary to have a slope as in the present invention. Therefore, in the present invention, fine processing is performed so that a slope can be formed.
[0063]
As the fine processing technique as described above, an electron beam drawing method can be used. In this method, first, a resist layer is formed on a glass substrate, and then the resist layer is exposed and developed by an electron beam drawing method and patterned to form a resist pattern layer. Thereafter, by using the resist pattern layer as a corrosion mask and corroding the glass substrate by a dry etching method or the like, a fine uneven shape is formed on the glass substrate. At this time, side etching is performed at the time of etching to form a slope. In addition, the resist pattern layer itself may be used directly as a corrosion mask when the glass substrate is corroded, but in order to form a deep uneven shape having a slope, a metal layer made of chromium or the like is preferably provided on the glass substrate. Thereafter, a resist film is formed to obtain a resist pattern layer, and the metal layer is formed as a metal pattern layer using this resist pattern layer, and it is preferable to use it as a corrosion mask.
[0064]
In forming a pattern on the resist film, a laser drawing method can be used in addition to the electron beam drawing method. In the laser drawing method, a laser interference method used for producing a hologram, a diffraction grating, or the like can be used. In the case of a diffraction grating, it is a one-dimensional arrangement, but a two-dimensional arrangement is also possible if multiple exposures are performed at different angles. However, in the laser interference method, the fine unevenness obtained is usually regularly arranged, but in the electron beam drawing method, in addition to the regular arrangement, irregular arrangement is also possible. Also, laser interferometry, which is a laser drawing method, has limitations on the directivity of the laser beam, and it is difficult to obtain stable patterning conditions over a large area. There is an advantage that it can be eliminated.
[0065]
The mold obtained as described above may be used directly for forming fine irregularities on a transparent substrate, but in the case of mass production, the mold is usually used as a mother plate and produced from the mother plate. Use the master version as a mold.
The master plate is produced by a known method, for example, metal plating such as nickel is performed on the mother plate, and the plating layer is peeled off to produce a metal master plate (electroforming method). Alternatively, the master plate is plated again and the master plate prepared again is used as a mold. In addition, as a type | mold which finally forms a fine unevenness | corrugation in a transparent base material, there can be a plate shape, a sheet shape, or a cylindrical shape.
[0066]
As a specific method for forming (duplicating) fine irregularities on a transparent substrate using the master plate (or mother plate) as a (shaping) mold as described above, for example, a hot press method (embossing method) ), An injection molding method, a 2P method (Photo Polymer method), or a known replication method, or a method of laminating a fine uneven shape forming sheet may be appropriately selected according to the material of the transparent substrate.
[0067]
Among these, the method for forming fine irregularities on an already tangible transparent substrate includes a hot press method (embossing method), a 2P method (Photo Polymer method), a sol-gel method, a laminating method of fine irregularities shaping sheet, and the like. . Among these, the hot press method (embossing method) is applied when the transparent substrate is generally made of a material such as a resin that can exhibit a plastically deformable state such as a thermoplastic resin. On the other hand, the 2P method (PhotoPolymer method), the sol-gel method, and the laminating method of the fine concavo-convex shaped sheet (or plate) can be applied even when the transparent substrate is made of an inorganic material such as glass.
[0068]
The sol-gel method (see Japanese Patent Application Laid-Open No. 6-64907) applies a composition containing metal alkoxide and the like and polyethylene glycol as a thickener, and embosses it by embossing while the sol is soft. This is a method of forming fine irregularities as an inorganic coating film by performing final drying and heat treatment after forming.
Further, the fine unevenness shaped sheet (or plate) is a product in which fine unevenness is already formed on a resin sheet or plate by using the above-mentioned mold or the like. As the resin, resins listed as materials for transparent substrates can be used. The concavo-convex shaped sheet (or plate) is adhered to a transparent substrate made of a plate material or a sheet material by an adhesive or heat fusion.
[0069]
Next, examples of the method for forming fine irregularities that are simultaneously formed during modeling of the transparent substrate itself include an injection molding method and a 2P method (Photo Polymer method).
The injection molding method uses an injection mold in which a fine concavo-convex shape is provided on the mold surface, and the fine concavo-convex shape is formed by the injection molding method. According to this method, since the transparent substrate itself and the fine irregularities can be simultaneously formed by molding using a resin, the method is extremely excellent in mass productivity. In order to provide the injection mold with a fine uneven shape for forming fine unevenness, the master plate (or mother plate) obtained as described above may be mounted on the mold surface.
In addition, the 2P method here is a method in which the transparent substrate itself is also shaped with fine irregularities at the same time.
[0070]
In addition, as a method of forming fine irregularities that are formed simultaneously with the modeling of the transparent base material itself, even when the transparent base material is glass, the glass can exhibit a state that can be plastically deformed by heating, so the hot press method is applied. And you may form a fine unevenness simultaneously with modeling of a transparent substrate.
[0071]
Of the various forming methods described above, those having a structure in which the transparent substrate 1 and the fine irregularities 2 are integrated as shown in FIG. 1B are the hot press method (embossing method), injection molding method, 2P. Obtained by the photopolymer method (Photo Polymer method), etc. Also, as shown in FIG. 7, the structure in which the substrate uneven portion 1B including the fine unevenness 2 is laminated on the transparent substrate 1A main body is an injection molding method (main body And 2P method (Photo Polymer method), sol-gel method, laminating method of fine concavo-convex shaped sheet (or plate), and the like.
[0072]
[Other components]
The transparent touch panel of the present invention only needs to have a structure with fine irregularities peculiar to the present invention on the back surface of the transparent base material constituting the outermost surface, and other parts adopt various structures of conventionally known various types of transparent touch panels. be able to.
[0073]
For example, as the same antireflection function, a conventionally known single layer or multilayer antireflection layer may be provided on the other surface of the transparent substrate. In addition, a layer imparting antiglare property (or antireflection) by light diffusion may be provided on the surface. Moreover, you may provide a conventionally well-known hard-coat layer in order to prevent a damage | wound on the surface of a transparent base material irrespective of the presence or absence of this antireflection layer. It is effective to provide the antireflection layer on the hard coat layer.
[0074]
For example, the cross-sectional view of FIG. 8 is a configuration in which an antireflection function in a form different from that of the present invention is provided on the surface of the transparent touch panel 10 with respect to the configuration of FIG. This is a transparent touch panel 10 in which a hard coat layer 5 and an antireflection layer 6 made of a multilayer film or the like are formed in this order on the surface of the transparent substrate 1a which is the outermost surface.
[0075]
[Display device]
The display device of the present invention is a display device having a configuration in which a display panel is disposed on the back side of the transparent touch panel of the present invention as described above. As a matter of course, in the display device, the back surface of the transparent touch panel and the surface of the display panel are arranged in such a manner that a gap is provided between the transparent touch panel back surface and the display panel surface without being completely adhered by an adhesive layer or the like. This is because there is almost no meaning of the antireflection effect peculiar to the present invention due to specific fine unevenness when they are brought into close contact.
[0076]
In the display device of the present invention, a device having only a display function (for example, an LCD monitor, a CRT monitor, etc.) may be used, but a device having a display function is also applicable as a part of the function of the device. For example, as described later in the application, it is a PDA or a portable information terminal, a car navigation system, or the like.
[0077]
Here, one embodiment of the display device 100 as described above is illustrated in the cross-sectional view of the main part of FIG.
The display device 100 in the figure is a cross-sectional view conceptually showing an arrangement centering on a display portion of a PDA or a portable information terminal, for example. In the display device 100 of the figure, the transparent touch panel 10 has fine irregularities on the back surface of the transparent base material that forms the backmost surface, and a flat panel display such as an LCD is provided with a space between the back side of the transparent touch panel 10. The display panel 30 is arranged. In addition, the display panel 30 is good also as what gave the antireflection function which consists of the fine unevenness | corrugation 2 peculiar to this invention to the front side surface which faces the transparent touch panel 10 mentioned above. Thereby, the antireflection function as the display device 100 is further improved.
[0078]
[Use of transparent touch panel]
The transparent touch panel according to the present invention can be used as input means (including a transparent tablet) in a display unit of various display devices. Such a display device with an input function includes, for example, an LCD (liquid crystal display), an ELD (electroluminescent display), an FPD (flat panel display) such as a plasma display (PDP), or a CRT as a display panel. The device used. In particular, since the display is not a self-luminous type, an LCD that is relatively susceptible to deterioration in display performance due to external light is preferable in that the effect of the present invention can be obtained more greatly. The display device according to the present invention includes a display device that displays information by mechanical means such as a mechanical analog meter represented by a timepiece having hands on a dial.
[0079]
Examples of various products having a display device with an input function as described above include PDAs such as electronic notebooks or portable information terminals (devices), car navigation systems, point-of-sale (POS) terminals, portable orders Input terminal, ATM (automatic cash deposit payment machine), facsimile, landline phone terminal, mobile phone terminal, digital camera, video camera, personal computer, PC display, television receiver, TV monitor display, ticket vending machine, measuring instrument There are electronic devices such as calculators and electronic musical instruments, office machines such as copiers and ECRs (cash register machines), and electrical products such as washing machines and microwave ovens.
[0080]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0081]
[Example 1]
An operation of forming a photosensitive resin resist layer on a glass substrate by spin coating, and exposing an argon ion laser from two directions at a 50 ° angle with a laser interference exposure apparatus is performed by rotating the substrate vertically and horizontally by 90 degrees. We went twice. Subsequently, it developed with the developing solution and the resist pattern layer was formed.
[0082]
Next, the glass substrate was corroded by a dry etching method to produce a mold (mother plate) made of a glass substrate on which a desired fine uneven shape was formed. On this mother plate, a die (master plate) made of nickel was produced by a nickel electroforming method used in a compact disc production line or the like.
[0083]
And for the transparent touch panel of the resistance film type, as the transparent base material 1 constituting the outermost surface, on the surface to be the outermost surface of the 1 mm thick glass plate on which ITO is formed as the resistance film on one surface (front side surface) The fine irregularities 2 were formed by the 2P method. Specifically, after the silane coupling treatment was performed on the back surface of the transparent substrate, an ultraviolet curable resin having the following composition was potted on the surface (coating amount conversion 2 g / m).²).
[0084]
[UV curable resin]
Tetrabromobisphenol A type epoxy acrylate 32 parts by mass
2-Phenyl-2- (4-acryloyloxyethoxyphenyl) propane
……………………………………………………………………………………………………………… 18 parts by mass
2,4,6-tribromophenyl ethoxy acrylate 50 parts by mass
1-hydroxycyclohexyl phenyl ketone 3 parts by mass
[0085]
Next, the master plate prepared as described above is pressed from above the resin mass on the transparent base material, and the resin is spread over the plate surface and remains in the pressure-bonded state. Then, the resin was cured by irradiating with ultraviolet rays, the master plate was peeled off, and desired fine irregularities were formed on the back surface of the transparent substrate made of a glass plate.
[0086]
On the back surface of the transparent substrate, the height H is determined by observation with an atomic force microscope._MIN200nm, period P_MAX2 were 300 m, and fine irregularities were formed in which a large number of shapes as shown in FIG.
[0087]
The reflectance of the transparent substrate was measured. First, a black vinyl adhesive tape was applied to the surface not subjected to antireflection treatment, and the spectrophotometer was measured at an incident angle of 5 ° from the normal to the antireflection treatment surface. The luminous reflectance reached a low value of 0.1%. In addition, the reflection prevention by fine unevenness | corrugation was 4% when the luminous reflectance was similarly measured about the transparent base material which was not processed.
[0088]
And the transparent base material which performed the said anti-reflective process, and the polyethylene terephthalate sheet | seat of 0.18 mm in thickness in which ITO film | membrane was formed were combined, and it assembled as a resistive film type transparent touch panel. The total light transmittance (transmitted from the back surface to the front surface) of this transparent touch panel was improved to 88%, compared with 83% in the case where the antireflection treatment was not performed on the back surface of the panel.
Further, this transparent touch panel was assembled as a display device having a structure arranged on the front surface of the LCD display panel.
[0089]
And the display device of the structure which has arranged the transparent touch panel which gave the above-mentioned antireflection processing in the front of the LCD display panel, and the display device which arranged the display panel on the front in the same way the above-mentioned anti-reflection processing untreated transparent touch panel Were visually compared in terms of the brightness of the same display image, the illuminance on the display surface of the same indoor light source and the incident angle of indoor light. As a result, the display device using the transparent touch panel of the present invention always displays even if the illuminance and angle of various light sources are changed, as compared with the display device combined with the anti-reflection treated untouched transparent touch panel. It was confirmed that the image looked bright, the contrast of the displayed image was clear, and the visibility of the display was good.
[0090]
【The invention's effect】
(1) According to the transparent touch panel of the display device of the present invention, light reflection on the back surface of the transparent touch panel can be reduced. That is, as the wavelength component that affects the visual recognition of the display, the reflected light from the back surface can be removed from the total reflected light from the front and back surfaces of the transparent touch panel (and the internal component surface depending on the method) of the external light coming from the outside of the transparent touch panel. Therefore, the total amount of reflected light can be reduced accordingly. Accordingly, it is possible to improve the visibility reduction of the display due to reflection of external light. In addition, the fine irregularities specific to the present invention provided for antireflection are present on the back surface and are not exposed on the surface (front side) of the transparent touch panel. The antireflection effect is not lowered due to wear due to wear, oil stains (filling of recesses), and the like.
In addition, when the display device is configured using the transparent touch panel of the present invention, reflection on the back surface of the transparent touch panel with respect to display light (observation light) from the display panel disposed on the back side of the transparent touch panel is also prevented, so that the display contrast. It is possible to prevent the display from decreasing and whitening of the display. Therefore, the visibility of display can be improved also in this respect. In addition, since visibility can be improved, for example, power of a display panel such as a backlight of a liquid crystal panel, a front light, or an EL panel is reduced, which contributes to energy saving and power saving.
[0091]
(2) Furthermore, if the relationship between the period of the fine irregularities and the refractive index of the transparent substrate is a specific relationship, the antireflection effect due to the fine irregularities having a specific shape can be obtained more completely.
[0092]
(3) Further, according to the display device of the present invention, the effect (1) or further (2) which is the effect of the transparent touch panel can be enjoyed. As a result, the visibility of the display is improved, and it contributes to energy saving and power saving of the display device.
[Brief description of the drawings]
FIG. 1 is a sectional view conceptually showing a transparent touch panel of the present invention.
FIG. 2 is a diagram (part 1) for conceptually explaining the distribution of effective refractive index obtained by fine unevenness.
FIG. 3 is a diagram (part 2) for conceptually explaining an effective refractive index distribution obtained by fine unevenness.
FIG. 4 is a diagram (part 3) for conceptually explaining the distribution of effective refractive index obtained by fine unevenness.
FIG. 5 is a cross-sectional view illustrating some of (vertical) cross-sectional shapes of fine irregularities.
FIG. 6 is a cross-sectional view illustrating some of arrangements of fine irregularities in a horizontal plane.
FIG. 7 is a cross-sectional view illustrating another embodiment of a transparent substrate in a transparent touch panel.
FIG. 8 is a cross-sectional view illustrating another embodiment of a transparent touch panel.
FIG. 9 is a cross-sectional view conceptually illustrating one form of a display device with respect to a display portion thereof.
[Explanation of symbols]
1 Transparent substrate (the backmost)
1a Transparent substrate (forms the outermost surface)
1A transparent substrate body
1B Uneven part of base material
2 Fine irregularities
2t The most convex part (of fine unevenness)
3, 3a resistive film
4 Spacers
5 Hard coat layer
6 Antireflective layer (not based on fine irregularities)
10 Transparent touch panel
30 Display panel
100 Display device
n Refractive index
n_a  Refractive index (air)
n_b  Refractive index (transparent substrate)
n₀  Refractive index
n₁  Refractive index
n_ef(Z) Effective refractive index
H_MIN  Minimum height (of fine irregularities)
I₀        Incident light
I_R      Reflected light on both sides
I_Rsurf    Surface reflected light
I_Rrear  Back side reflected light
P_MAX  Period (at the most convex part of fine irregularities)
R reflectance
λ_MIN  Minimum wavelength
λ_MAX  Maximum wavelength

Claims (3)

In the transparent touch panel having the antireflection function on the back surface of the transparent base material forming the outermost surface,
The antireflection function is formed by forming anti-reflection fine irregularities on the back surface of the transparent substrate, and the fine irregularities have a minimum wavelength λ _MIN in the vacuum in the wavelength band of visible light and the fine irregularities. When the period at the most convex part of the unevenness is P _MAX ,
P _MAX ≦ λ _MIN
Have the relationship
In addition, the cross-sectional area occupation ratio of the material portion of the transparent base material in the cross section when it is assumed that the fine unevenness is cut by a plane orthogonal to the unevenness direction goes from the most convex portion to the most concave portion. continuously go gradually increased in accordance with, and 1 at the top recess, Ri irregularities der,
The fine unevenness is formed using a mold . A transparent touch panel with an antireflection function. Further, the refractive index of the transparent substrate when the n _b,
P _MAX ≦ λ _MIN / n _b
The transparent touch panel with an antireflection function according to claim 1, wherein   A display device, further comprising a display panel disposed on the back side of the transparent touch panel with an antireflection function according to claim 1.

Images