JP3746403B2 - Liquid crystal display - Google Patents

Description

表１に示したように、具体例１の構成（レンズピッチ０．１ｍｍ）では、傾斜角θ２が５゜〜８５゜の範囲においてモアレ縞の発生を実質的に防止することができる。また、具体例１の構成において０．１１ｍｍピッチのレンズを用いると、傾斜角θ２が６゜〜８４゜の範囲においてモアレ縞の発生を実質的に防止することができる。このように、レンズピッチが変わると、モアレ縞の発生を抑制できる傾斜角範囲が変わる。さらに、レンズピッチが０．１４ｍｍの場合には、モアレ縞が実質的に発生しない傾斜角θ２の範囲が不連続となっている。例えば、傾斜角θ２が小さい側では、６゜〜１０゜および２０゜〜２５゜ではモアレ縞の発生は実質的に防止されるが、１０゜〜２０゜（両端を含まない）の範囲ではモアレ縞の発生が確認される。このように、モアレ縞の発生を抑制する条件が、レンズピッチと傾斜角に大きく依存している。
【００４６】
また、モアレ縞の発生を実質的に防止できる傾斜角の範囲の幅は、例えば、具体例１の構成において１４０ｍｍピッチのレンズを用いた場合、最小でも４゜（傾斜角６゜〜１０゜）が得られる。従って、所定の傾斜角範囲の相対配置を有するように液晶セルとレンズアレイとを貼り合わせる工程において要求される傾斜角の精度は、±２゜であり、現有のプロセス精度で十分に実現できる。
【００４７】
モアレ縞の発生と傾斜角θ２との関係を他の液晶表示装置（具体例２）について調べた結果を表１に合わて示す。具体例２は、液晶セルとして、対角１８インチ、ストライプ配列の水平絵素数１２４０（Ｒ、Ｇ、Ｂのそれぞれに対して１２４０）、垂直絵素数９６０、絵素ピッチ（水平方向Ｐｈが、０．０９５ｍｍ、垂直方向Ｐｖが０．２８６ｍｍ）を用いた。表１において具体例１と具体例２とを比較すると明らかなように、液晶セルの周期構造が変化すると、レンズアレイの周期構造が同じでも、モアレ縞の発生を抑制できる傾斜角θ２の範囲は異なる。
【００４８】
上述したように、モアレ縞の発生を抑制するための傾斜角θ２の範囲は、液晶セルの周期構造およびレンズアレイの周期構造に大きく依存する。モアレ縞の発生を抑制できる条件、すなわち、それぞれの周期構造（絵素ピッチ、レンズピッチ）と傾斜角との関係を数式を用いて一般化するのは困難であるが、モアレ縞の発生を抑制できる傾斜角θ２（θ２＞０）の範囲は、実験的に容易に見いだすことができる。また、モアレ縞の発生を抑制できる傾斜角θ２（θ２＞０）の範囲は、数度（表１に示した例では、少なくとも４゜）あるので、液晶セルとレンズアレイとの貼り合わせ工程における位置あわせ精度は、現行プロセスで十分に実現できる範囲内にある。
【００４９】
モアレ縞の発生を抑制するためには、表示面全面に亘って（ｄ２方向において）絵素とレンズが一対一で対応することが無いように設定することが好ましく、Ｐ３・ｃｏｓθ２≦Ｐ２の関係を満することが好ましい。表示面における均一性を考慮すると、Ｐ３・ｃｏｓθ２≦Ｐ２／２、さらに好ましくは、Ｐ３・ｃｏｓθ２≦Ｐ２／６であることが好ましい。ただし、Ｐ３があまり小さくなくると、レンズ幅Ｐｗも小さくなり、レンズアレイの形成が困難（精度の低下等による）となるので、Ｐ３は約１０μｍ以上であることが好ましいが、特に制限は無い。
【００５０】
次に、本実施形態１の液晶表示装置の視角特性を調べた結果を図３に示す。図３は、具体例１の液晶表示装置（傾斜角８゜；レンズピッチ０．１ｍｍ）の視角依存性を示すグラフであり、横軸は視角（表示面法線と観察方向とのなす角）を縦軸はコントラスト比を示す。なお、視角は、表示面内の６時方向（下側）を正（グラフ右側）、１２時方向（上側）を負（グラフ左側）として表している。すなわち、図３は、レンズによって視角を広げたい方向における視角依存性を示している。比較のために、レンズアレイを設けていない従来のＴＮモードの液晶表示装置（比較例）の視角特性を図３に合わせ示している。
【００５１】
図３から明らかなように、具体例１の液晶表示装置の視角依存性は、比較例の液晶表示装置の視角依存性に比較し、著しく小さくなっており、広い視角範囲（視角範囲±８０゜）に亘って高いコントラスト比（ＣＲ≧１０）を実現している。なお、傾斜角θ２が大きくなると、レンズによって視角が広がる方向が本来視角を広げたい方向からずれるので、傾斜角があまり大きくなると所望の視角特性が得られない場合がある。傾斜角θ２が３０゜以下であれば、表示の観察に影響を与えないことを実験的に確認した。従って、視角依存性の方位角（表示面内方向）依存性を考慮すると、傾斜角θ２の範囲は、モアレ縞の発生を抑制する範囲で、且つ３０゜以下であることが好ましい。なお、液晶表示装置に要求される視角特性は、液晶表示装置の用途にもよるので、傾斜角の範囲（特に上限値）は上記の範囲外であってもよい場合がある。
【００５２】
上述の具体例では、ストライプ配列の絵素を有する液晶セルに対してレンチキュラーレンズ有するレンズアレイを配設した構成を例示したが、本発明はこれらに限定されない。例えば、図４に示したように、図２のｄ３方向に直交するｄ４方向にピッチＰ４で周期的に配列され、ｄ４方向を含む面内から入射する光に対してレンズ機能を有するレンズ（レンズ幅Ｐｗ’）を用いてもよい。この場合、液晶セルのｄ１方向の周期構造（ピッチＰ１）とレンズアレイのｄ４方向との周期構造（ピッチＰ４）との干渉に起因するモアレ縞の発生を抑制・防止するためには、θ４＞０で、表示面全面に亘って、ｄ１方向において、絵素とレンズが一対一で対応することが無いように、Ｐ４・ｃｏｓθ３≦Ｐ１の関係を満足することが好ましい。また、表示面における均一性を考慮すると、上述と同様に、Ｐ４・ｃｏｓθ３≦Ｐ１／２、さらに好ましくは、Ｐ４・ｃｏｓθ３≦Ｐ１／６であることが好ましい。ただし、Ｐ４があまり小さくなくると、レンズ幅Ｐｗ’も小さくなり、レンズアレイの形成が困難（精度の低下等による）となるので、Ｐ４は約１０μｍ以上であることが好ましいが、特に制限は無い。また、上述したように、傾斜角が大きいと視角特性の方位角依存性が大きくなるので、傾斜角θ３は３０゜以下であることが好ましい。
【００５３】
上述のように、本実施形態によると、レンズアレイを液晶表示パネルに接着層を介して接合した構成においても、効果的にモアレ縞の発生を抑制・防止することができるので、高品位の表示が可能な広視野角液晶表示装置を提供することができる。なお、レンズアレイと液晶表示パネルとを接着層を介することなく、例えば周辺部において接着する構造に対して、本実施形態を適用してもモアレ縞の発生を抑制・防止できることは言うまでもない。
【００５４】
（参考実施形態２）
図５に参考実施形態２の透過型液晶表示装置５００の模式的な断面図を示す。液晶表示装置３００は、液晶表示パネル１００ａと、液晶表示パネル１００ａに光を照射する面光源１０１と、レンズアレイ５０３とを有している。液晶表示パネル１００ａと面光源１０１は実施形態１の液晶表示装置１００と同じものが用いられるので、それぞれの構成要素を同じ参照符号で示し、ここでは説明を省略する。また、液晶表示装置５００において、レンズアレイ５０３と液晶表示パネル１００ａとの接合に接着層（図１の１０６）を用いていない。液晶表示パネル１００ａおよびレンズアレイ６０３の接合は、液晶表示パネル１００ａおよびレンズアレイ６０３の周辺部において、接着剤等を用いて接合されている（不図示）。
【００５５】
本参考実施形態の液晶表示装置５００においては、レンズアレイ６０３のレンズ６０３ａは、液晶表示パネル１００ａの絵素に対して面光源１０１とは反対側に焦点を有するように配置されている。実施形態１のように粘着層を用いることなく、液晶表示パネル１００ａおよびレンズアレイ５０３の周辺部で接合すると、モアレ縞は比較的観察され難い。レンズアレイのレンズが液晶表示パネル１００ａの絵素に対して面光源１０１とは反対側に焦点を有するように配置し、実施形態１の構成と組み合わせることによって、より効率的にモアレ縞の発生を防止することができる。
【００５６】
以下では、絵素の周期構造に対するレンズアレイの周期構造の傾斜角を０゜とした例について説明する。
【００５７】
図６は、液晶表示パネル１００ａの絵素の配置と、レンズアレイ６００（図５のレンズアレイ６０３の一例）のレンズ６０１の配置との関係を説明するための模式図である。図６（ａ）は上面図であり、図６（ｂ）は図６（ａ）のｄ３方向（ピッチＰ３方向）に沿った断面図である。
【００５８】
レンズアレイ６００は、ピッチＰ３（＝レンズ幅Ｐｗ）で規則的配列された複数のレンチキュラーレンズ６０３を有している。この周期方向ｄ３は、絵素の列方向ｄ２の周期Ｐ２（Ｐｖ）と同じである（傾斜角が零度）。
【００５９】
具体例３の液晶表示装置として、実施形態１の具体例１で用いた液晶表示パネル１００ａ（２０インチ）に対し、レンズピッチ（Ｐ３）が０．１４ｍｍ、レンズ高さＲｈが０．０４ｍｍ、焦点距離ｆが０．１４ｍｍの凸レンズを有するレンズアレイを用いた。この具体例３の液晶表示装置において、レンズアレイから絵素までの空気換算距離ｄａは、０．６６ｍｍ（０．７／１．５２＋０．３／１．５２）であり、焦点距離ｆ（＝０．１４）はレンズアレイから絵素までの空気換算距離ｄａ（＝０．６６ｍｍ）よりも短くなっている。従って、絵素を透過した光はレンズによって拡散され、複数の絵素が形成する像はぼやけるので、絵素の周期構造が目立たなくなり、その結果、モアレ縞の発生が抑制される。レンズの焦点距離ｆの下限値は、レンズ幅をＰｗ、屈折率ｎ１とすると、Ｐｗ／｛２・（ｎｌ−１）｝となる。これよりも焦点距離ｆを短かくするためには、レンズの幅よりもレンズの高さが大きなレンズを形成する必要があり、レンズの形成が困難となる。
【００６０】
具体例３の構成において、焦点距離を変化させてモアレ縞の発生を目視で評価した結果を示す。
【００６１】
【表２】

表２中において、×はモアレ縞の周期が０．５ｍｍ以上の幅で観察され、表示品位の低下が認められたものを示し、△は、モアレ縞の周期が０．３ｍｍ〜１．０ｍｍの幅で観察され、表示品位が若干低下したものを示し、○はモアレ縞の周期が０．０９ｍｍ以下となり表示品位の低下が認められなかったものを示す。なお、評価結果が△の液晶表示装置も用途によって使用できる。
【００６２】
表２の結果から明らかなように、焦点距離ｆが上記空気換算距離ｄａとほぼ等しい場合には、モアレ縞が観察され表示品位が低下することがわかる。表２から、焦点距離ｆは０．５ｍｍ以下が好ましいこと、すなわち空気換算距離ｄａの約０．７５倍以下であることが好ましいことがわかる。レンズアレイのレンズの焦点距離ｆは、用いる液晶表示パネル１００ａの空気換算距離ｄａ（カラーフィルタ基板の厚さや屈折率など）に応じて、上記の条件を満足するように適宜設定すればよい。
【００６３】
図７に具体例３の液晶表示装置の視角特性を示す。図７は、図３と同様の視角特性を示すグラフであり、比較のために実施形態１の比較例と同じ液晶表示装置の視角特性を合わせて示してある。図７から明らかなように、具体例３の液晶表示装置の視角依存性は、比較例の液晶表示装置の視角依存性に比較し、著しく小さくなっており、広い視角範囲（視角範囲±８０゜）に亘って高いコントラスト比（ＣＲ≧１０°）を実現している。
【００６４】
本参考実施形態の液晶表示装置に用いられるレンズアレイは、上述の例に限られない。焦点距離が上述の関係を満たせば、図４を参照しながら実施形態１で説明したように、ｄ３方向に直交するｄ４方向にもレンズ機能を有するレンズを用いてもよいことは勿論である。
【００６５】
さらに、図６（ｃ）に示すように、図６（ｂ）に示したレンズアレイ６００に代えて、複数の凹レンズ７０１を有する用いることもできる。例えば、凹レンズ７０１のピッチＰ３を０．１４ｍｍ、高さＲｈを−０．０４ｍｍとすることによって、具体例３と同等の表示特性を得ることができる。凹レンズ７０１は、観察者側に焦点を有するので、液晶表示パネル１００ａの絵素の像をぼかす作用を有するので、モアレ縞の発生を抑制・防止する効果がある。
【００６６】
凹レンズ７０１を有するレンズアレイ６００は、例えば、以下の方法で作製できる。所定の形状の凹部が複数形成されたマスター金型を用いて、アクリル樹脂を射出成形することによって、複数の凸部を有するアクリル樹脂板を形成する。このアクリル樹脂板の表面に電鋳法を用いてニッケル層を形成し、成形型を得る。このニッケル層は、成形型の表面硬度を向上させる。次に、成形型に紫外線硬化樹脂（例えば、日本合成ゴム（株）社製Ｚ９００１；屈折率１．５９）を滴下し、紫外線を照射（例えば、約１．０Ｊ／ｃｍ２）することによって紫外線硬化樹脂を硬化し、レンズシート基材（例えば、日本合成ゴム（株）社製のアートンフィルム）に所定の形状の凹部が転写形成されたレンズアレイを得る。
【００６７】
上述の実施形態１及び参考実施形態２では、ＴＮ型の液晶表示パネルを用いた液晶表示装置を例に本発明を説明したが、ＳＴＮ型やＥＣＢモードなど他の表示モードの液晶表示パネルを用いることができる。また、絵素の配列もストライプ配列に限られず、デルタ配列の絵素を有する液晶表示パネルを用いてもよい。また、レンズによって視角を拡大する方向は、用いる液晶表示パネルの表示モードや偏光板の配置などを考慮して適宜設定すればよい。また、レンズアレイの製造方法は例示した方法に限られず、公知の方法で製造できる。なお、例示の方法を用いると本願発明のレンズアレイを効率よく製造することができる。
【００６８】
【発明の効果】
本発明によると、液晶表示装置の液晶表示パネルの複数の絵素の周期方向とレンズアレイの複数のレンズの周期方向とが互いに交差するように配置されているので、干渉によるモアレ縞の発生が抑制される。また、レンズアレイと液晶表示パネルとをレンズの一部に接触する接着層を介して貼り合わせた構造であるが、モアレ縞の発生を抑制・防止することができる。さらに、絵素とレンズとの間に特定の位置関係が要求されないので、絵素ピッチやレンズピッチの高精度な制御や高い貼り合わせ精度は要求されず、従来の製造装置を用いて従来のプロセスで製造することができる。
【００６９】
このように、本発明によると、視角特性に優れかつモアレ縞の発生が抑制・防止された、表示品位の優れた液晶表示装置が提供される。本発明は、特に大型の直視型液晶表示装置に好適に適用される。
【図面の簡単な説明】
【図１】本発明による実施形態１の透過型液晶表示装置１００の模式的な断面図である。
【図２】実施形態１の液晶表示装置１００における、液晶表示パネルの絵素の配置とレンズアレイのレンズの配置との関係を説明するための模式図である。
【図３】実施形態１の液晶表示装置の視角特性を示すグラフである。
【図４】本発明で用いられるレンズアレイの断面図（図２（ｂ）と直交する方向に沿った断面図）である。
【図５】本発明による参考実施形態２の透過型液晶表示装置５００の模式的な断面図である。
【図６】参考実施形態２の液晶表示装置５００における、液晶表示パネルの絵素の配置とレンズアレイのレンズの配置との関係を説明するための模式図である。
【図７】参考実施形態２の液晶表示装置の視角特性を示すグラフである。
【符号の説明】
１００、５００ 液晶表示装置
１００ａ 液晶表示パネル
１０１ 面光源
１０２ａ、１０２ｂ 偏光素子
１０３、２００、５０３、６００、７００ レンズアレイ
１０４ａ、１０４ｂ 基板
１０５ 液晶層
１０５ａ シール剤[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly to a transmissive liquid crystal display device having wide viewing angle characteristics.
[0002]
[Prior art]
A liquid crystal display device is a display device that represents a flat panel display, like a cathode ray tube (CRT), a plasma display panel (Plasma Display Panel: PDP), or an electroluminescent display device (Electro Luminescence Display: EL). . Since the liquid crystal display device has features such as light weight, thinness, and low power consumption, it is widely used for OA equipment, in-vehicle TVs, car navigation, video camera monitors, and the like. Among liquid crystal display devices, a transmissive liquid crystal display device is often used because the contrast ratio is superior to that of a reflective type.
[0003]
However, the liquid crystal display device has a problem that the viewing angle dependency of display quality is large. The viewing angle dependency means, for example, that when the display surface is observed from a direction inclined at a certain angle or more, the image that should be displayed in black is observed whitish, or the gradation is reversed in the halftone display. Say to change by. A viewing angle range in which the observer can normally observe the display (for example, at a predetermined contrast ratio or higher) is called a viewing angle. The viewing angle of a liquid crystal display device having a large viewing angle dependency is narrow.
[0004]
The viewing angle dependency is caused by various causes. Twisted orientation of liquid crystal molecules (spiral direction and pretilt direction), refractive index anisotropy of liquid crystal molecules (difference in retardation depending on the light traveling direction), polarizing plate characteristics (degree of polarization selectivity), orientation of surface light source Sex can be cited as the cause.
[0005]
In general, a transmissive liquid crystal display device is designed so that the direction in which the display is most easily seen falls within the normal use range of an observer in consideration of viewing angle dependency. For example, it is designed so that the contrast ratio when viewed from the normal direction of the center of the display surface or the direction inclined slightly below (6 o'clock direction) is higher than the contrast ratio when viewed from other directions. ing.
[0006]
A lens having a plurality of lenses on the viewer side of the liquid crystal display panel in order to improve the viewing angle characteristics of the transmissive liquid crystal display device, in particular to reduce the viewing angle dependency in the vertical direction (12 o'clock direction and 6 o'clock direction). A liquid crystal display device in which an array (or a lens sheet) is arranged is disclosed in, for example, Japanese Patent Laid-Open Nos. 9-127309, 7-120743, 8-76120, and 6-230358. Is disclosed.
[0007]
[Problems to be Solved by the Invention]
However, as a result of examination by the inventors of the present application, in the liquid crystal display device disclosed in the above-mentioned publication, although the viewing angle characteristics are improved by arranging the lens array on the viewer side of the liquid crystal display panel, moire fringes are not observed. There is a problem that it is likely to occur and as a result, the display quality is degraded.
[0008]
In general, when two objects having a periodic structure such as a slit are overlapped, the periodic structures interfere with each other, and light and dark stripes called moire fringes are generated. In the liquid crystal display device disclosed in the above publication, a periodic structure formed by a plurality of picture elements of a liquid crystal display panel and a periodic structure formed by a plurality of lenses of a lens array arranged in front of the liquid crystal display panel interfere with each other. Then, moire fringes are generated. Furthermore, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-127309 etc., when the lens array and the liquid crystal display panel are bonded together via an adhesive layer that contacts a part of the lens, the lens is refracted at the adhesive portion. Moire fringes become conspicuous when the rate change is reduced and the lens effect at that portion is reduced.
[0009]
In the above Japanese Patent Laid-Open No. 9-127309, the pitch of the lens of the lens array is made smaller than the pixel pitch (arranged so that a plurality of lenses correspond to one picture element), thereby moire fringes. It can be reduced. However, in order to reduce moire fringes by adjusting the pitch, it is necessary to control the pixel pitch and the lens pitch with high accuracy, respectively, and high accuracy is required for bonding the lens array and the liquid crystal display panel. There is a problem that.
[0010]
Further, as disclosed in the above Japanese Patent Laid-Open No. 6-230358, when a concave lens is arranged for each picture element, there is a problem that the light distribution within one picture element is distorted and the display quality is lowered. .
[0011]
The present invention has been made to solve the above-mentioned problems, and its main object is to provide a liquid crystal display device with excellent display quality, which has excellent viewing angle characteristics and suppresses / prevents the generation of moire fringes. There is.
[0012]
[Means for Solving the Problems]
The liquid crystal display device of the present invention includes a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates and a pair of polarizing elements disposed so as to sandwich the liquid crystal layer, and irradiating the liquid crystal display panel with light. And a lens array disposed on the opposite side of the liquid crystal display panel from the surface light source, the liquid crystal display panel having a first pitch (P1) in a first direction. ), And a plurality of picture elements regularly arranged at a second pitch (P2) in a second direction intersecting the first direction, and the lens array has a third pitch in the third direction. A plurality of lenses regularly arranged in (P3) and having a function of changing a traveling direction of light incident from within a plane including the third direction, and a periodic structure of the plurality of lenses and the liquid crystal display panel It does not interfere with the periodic structure of Are arranged such that the third direction intersects the first and second directions And an adhesive layer that joins the lens array and one of the pair of polarizing elements, wherein the adhesive layer is in contact with a part of the surface of each lens of the plurality of lenses. This achieves the above objective.
[0013]
The second angle (θ2) between the third direction and the second direction is the same as the first angle (θ1) between the third direction and the first direction, or The third pitch (P3) is preferably small (θ2 ≦ θ1) and the second pitch (P2) preferably satisfies the relationship P3 · cos θ2 ≦ P2.
[0014]
Each of the plurality of lenses may be a lenticular lens extending in a fourth direction orthogonal to the third direction.
[0015]
The plurality of lenses are regularly arranged at a fourth pitch (P4) in a fourth direction orthogonal to the third direction and forming a third angle (θ3) with the first direction, Further having a function of changing the traveling direction of light incident from within the plane including the direction of four, and
The fourth pitch (P4) may satisfy the relationship of the first pitch (P1) and P4 · cos θ3 ≦ P1.
[0016]
It is preferable that the second angle θ2 formed by the third direction and the second direction is 30 ° or less.
[0017]
The plurality of lenses are preferably disposed so as to have a focal point on the opposite side of the surface light source with respect to the plurality of picture elements of the liquid crystal display panel.
[0018]
Each of the plurality of lenses is a convex lens having a focal length f, a lens width Pw, and a refractive index nl, from a surface on which the plurality of lenses are formed to a surface on which the plurality of picture elements are formed. It is preferable that the air conversion distance da satisfies the relationship of Pw / {2 · (nl−1)} ≦ f <da.
[0019]
The operation of the present invention will be described below.
[0020]
In the liquid crystal display device of the present invention, the periodic directions of the plurality of picture elements formed on the liquid crystal display panel and the periodic directions of the plurality of lenses formed on the lens array are arranged to intersect each other. That is, the lens is arranged so that the periodic direction of the lens is inclined with respect to the periodic direction of the picture element (inclination angles: θ, θ> 0). With this arrangement, the positional relationship (overlapping, etc.) between the picture element and the lens differs depending on the position of the picture element, so that the generation of moire fringes due to interference is suppressed. Also, Since the direction of the periodic structure of the lens is inclined with respect to the direction of the periodic structure of the picture element, the lens array and the liquid crystal display panel are bonded together via an adhesive layer that contacts part of the lens. Thus, the generation of moire fringes can be suppressed and prevented, and therefore a liquid crystal display device that can be manufactured by a simple method and has a simple structure can be realized. further Since no specific positional relationship is required between the picture element and the lens, high-precision control of the picture element pitch and lens pitch and high bonding accuracy are not required.
[0021]
In this specification, “picture element” refers to a minimum unit in which an optical state is controlled in order to perform display. In color display, typically, the minimum display units of R, G, and B are referred to as R picture element, G picture element, and B picture element, respectively. A set of R picture elements, G picture elements, and B picture elements form a pixel. The picture element is defined for each picture element electrode of the liquid crystal display device. The plurality of picture elements are typically arranged in a matrix. Accordingly, the plurality of picture elements are periodically arranged in the row direction and the column direction orthogonal thereto. The row direction and the column direction are called “periodic directions” of picture elements. Each picture element typically has a substantially rectangular shape, and therefore the period (referred to as “picture element pitch”) differs between the row direction and the column direction. Similar to the picture elements, the lenses of the lens array are generally arranged at different lens pitches in the row direction and the column direction. As described above, the row direction and the column direction are typically orthogonal to each other, but the arrangement of the picture elements and the lenses is not limited to this, and may be different directions. For example, in a delta arrangement color liquid crystal display device, the column direction can be set in a direction inclined with respect to the row direction.
[0022]
When generalized, the plurality of picture elements of the liquid crystal display panel are regularly arranged at the first pitch (P1) in the first direction and at the second pitch (P2) in the second direction intersecting the first direction. ing. With respect to this liquid crystal display panel, for example, the plurality of lenticular lenses are regularly arranged at the third pitch (P3) in the third direction intersecting the first and second directions, whereby the effect of the present invention is achieved. can get. The lenticular lens is typically a hemi-cylindrical lens having a semicircular cross section along the third direction, and has a function of changing (refracting) the traveling direction of light incident from within the plane including the third direction. Therefore, the in-plane viewing angle characteristics including the third direction can be improved (the viewing angle can be increased).
[0023]
In addition, the inclination angle θ is preferably set so that there is no one-to-one correspondence between picture elements and lenses over the entire display surface. When the inclination angle of P3 with respect to P1 is θ1, the inclination angle of P3 with respect to P2 is θ2, and θ2 ≦ θ1, the relationship of P3 · cos θ2 ≦ P2 may be satisfied. That is, if the second direction (inclination angle θ2) is closer to the third direction out of the first and second directions, the relationship of P3 · cos θ2 ≦ P2 may be satisfied.
[0024]
Instead of the lenticular lens, a lens array having a structure regularly arranged at a fourth pitch (P4) in a fourth direction different from the third direction (typically orthogonal) may be used. By using a lens further having a curved surface along the fourth direction, it is possible to improve the viewing angle characteristics in the plane including the fourth direction (widen the viewing angle). At this time, in order to suppress / prevent the occurrence of moire fringes due to interference between the periodic structure in the fourth direction and the periodic structure of the picture element, the fourth direction is a direction intersecting the first direction (inclination angle θ3 > 0), and the fourth pitch (P4) more preferably satisfies the relationship of the first pitch (P1) of the picture element and P4 · cos θ3 ≦ P1. When the first and second directions are orthogonal to each other and the third and fourth directions are orthogonal to each other, the relationship P4 · cos θ2 ≦ P1 is automatically satisfied if the relationship P3 · cos θ2 ≦ P2 is satisfied. .
[0025]
If the above relationship is satisfied, the occurrence of moire fringes can be prevented, but the symmetry of the viewing angle characteristics may be lost and the display quality may deteriorate. The inventor has found that the inclination angle (θ2) is preferably 30 ° or less in order to reduce moiré fringes and to ensure sufficient symmetry of the azimuth angle dependency of the viewing angle characteristics.
[0026]
Furthermore, by arranging the plurality of lenses of the lens array so as to have a focal point on the side opposite to the surface light source with respect to the plurality of picture elements of the liquid crystal display panel, generation of moire fringes can be suppressed / prevented. . When a convex lens is used in the lens array and the lens is focused on the picture element (between the color filter and the liquid crystal layer), the periodic structure of the picture element is emphasized by the lens. there were. As described above, by setting the focal point of the lens to the observer side of the picture element, the periodic structure of the picture element can be optically blurred, so that the generation of moire fringes can be suppressed / prevented. Specifically, a convex lens with a short focal length or a concave lens may be used. Even if a convex lens with a long focal length (focused on the light source side of the picture element) is used, the periodic structure of the picture element can be optically blurred, but the lens effect is reduced, so the effect of wide viewing angle is short. Since it is inferior to a focal length lens, it is not preferable.
[0027]
Consider the conditions for preventing moiré fringes from being observed. The resolution of a human eye with a visual acuity of 1.0 is represented by an index called a Randle ring, and is defined as a visual acuity that can identify a 1.5 mm break from a distance of 5 m. Based on this index, if the period of the moire fringes is less than 0.09 mm, even if an observer with a visual acuity of 1.0 observes the display surface (surface on which the picture element is formed) from a position 300 mm away, the moire pattern is observed. The stripes cannot be identified. Therefore, generally, if the above conditions are satisfied, it is considered that a high-quality display in which moire fringes are not recognized by an observer can be provided.
[0028]
In order to satisfy the above condition, when using a convex lens, each of the plurality of lenses has a focal length f, a lens width Pw, a refractive index nl, and a plurality of pictures from the surface on which the plurality of lenses are formed. It is preferable that the air equivalent distance da to the surface where the element is formed satisfies the relationship of Pw / {2 · (nl−1)} ≦ f <da.
[0029]
The configuration in which the lens is arranged so as to have a focal point opposite to the surface light source with respect to the plurality of picture elements of the liquid crystal display panel is a configuration in which the direction of the periodic structure of the lens is inclined with respect to the direction of the periodic structure of the picture element It is used in combination.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below with reference to the drawings.
[0031]
(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of a transmissive liquid crystal display device 100 according to the first embodiment. The liquid crystal display device 100 includes a liquid crystal display panel 100a, a surface light source 101 that irradiates light to the liquid crystal display panel 100a, and a lens array 103.
[0032]
The liquid crystal display panel 100a includes a liquid crystal layer 105 sandwiched between a pair of substrates 104a and 104b, and a pair of polarizing elements (typically polarizing plates or polarizing films) disposed so as to sandwich the liquid crystal layer 105. Prepare. A plurality of pixel electrodes (not shown) made of a transparent conductive material (eg, indium tin oxide: ITO) are formed in a matrix on the surface of one substrate (eg, active matrix substrate) 104a on the liquid crystal layer 105 side. Has been. Each of the pixel electrodes is ON / OFF controlled by a thin film transistor (TFT). A counter electrode (common electrode) and a color filter layer made of a transparent conductive material are formed on the surface of the other substrate (for example, color filter substrate) 104b on the liquid crystal layer 105 side (both not shown). For example, a nematic liquid crystal material prepared to have a twist angle of 90 ° is injected between both the substrates 104a and 104b and sealed with a sealant 105a. In order to obtain a predetermined alignment, alignment films (not shown) may be formed on the surfaces of the substrates 104a and 104b on the liquid crystal layer 105 side. The liquid crystal display panel 100a is not limited to the above example, and a wide variety of known liquid crystal display panels can be used. Note that it is preferable to use a TN mode liquid crystal display panel from the viewpoint of contrast ratio and response speed. As the surface light source 101, a known surface light source can be widely used.
[0033]
A lens array 103 is bonded to the viewer side (the side opposite to the surface light source 101) of the liquid crystal display panel 100 a through an adhesive layer 106. The lens array 103 includes a plurality of lenses 103a. The adhesive layer is in contact with a part of the surface of each of the plurality of lenses Yes. The lens 103a may be formed on the glass substrate 103b. The lens array 103 is typically formed in a sheet shape and may be called a lens sheet. In this specification, “lens” refers to an optical element having a function of changing (refracting) the traveling direction of light, and does not need to have a focal point. Typically, as shown in FIG. 1, a lens array having a plurality of lenticular lenses (or hemi-cylindrical lenses) 103a having a semicircular cross section is used.
[0034]
In the liquid crystal display device 100, the periodic structure of the picture elements of the liquid crystal display panel 100a and the periodic structure of the lenses 103a of the lens array 103 are arranged so as not to interfere with each other. This arrangement relationship will be described with reference to FIG.
[0035]
FIG. 2 is a schematic diagram for explaining the relationship between the arrangement of the picture elements of the liquid crystal display panel 100a and the arrangement of the lenses 201 of the lens array 200 (an example of the lens array 103 of FIG. 1). 2A is a top view, and FIG. 2B is a cross-sectional view along the d3 direction (pitch P3 direction) in FIG. 2A. FIG. 2C shows another example of the cross section shown in FIG.
[0036]
As shown in FIG. 2A, the liquid crystal display panel 100a includes a plurality of picture elements 100b arranged in a matrix in a row direction (d1 direction) and a column direction (d2 direction) orthogonal to each other. . In the illustrated example, a typical pixel array arranged in a matrix is shown, but the present invention is not limited to this, and is periodically (regularly) in two different directions (d1 direction and d2 direction). ) A liquid crystal display panel having arranged picture elements can be used. Each picture element 100b has a rectangular shape with a pitch P1 (typically a horizontal pitch Ph) in the row direction (d1 direction) and a pitch P2 (typically a vertical direction) in the column direction (d2 direction). Are periodically arranged at a pitch Pv).
[0037]
Diagonal 20 inches (vertical: 304.8 mm, horizontal: 406.4 mm), striped array of horizontal picture elements 640 (640 for each of R, G, B), vertical picture element count 480, picture element pitch (horizontal direction) Ph is 0.212 mm, the vertical direction Pv is 0.635 mm), the thickness of the color filter substrate (stripe arrangement) is 0.7 mm, the refractive index is 1.52, and the thickness of the polarizing plate 102b on the viewer side is 0.00. The lens array 200 is bonded to the liquid crystal display panel 100a having a thickness of 30 mm and a refractive index of 1.52 using an adhesive layer 106 made of acrylic resin and having a thickness of 0.02 mm and a refractive index of 1.50. A display device was produced.
[0038]
In the lens array 200, a plurality of lenticular lenses 201 are periodically arranged at a pitch P3 in the d3 direction. In the example shown in FIG. 2B, the lens width Pw of each lens 201 is the same as the lens pitch P3. However, the present invention is not limited to this, and a lens array 200 ′ shown in FIG. A lens 201 ′ having a width Pw smaller than the lens pitch P3 may be used. From the viewpoint of light use efficiency, the ratio (Pw / P3) of the lens width Pw to the lens pitch P3 is preferably 0.9 or more.
[0039]
Specifically, the lens 201 is an ultraviolet curable resin (for example, manufactured by Nippon Synthetic Rubber Co., Ltd.) filled and cured in a mold having a predetermined recess on a transparent substrate (for example, Arton film manufactured by Nippon Synthetic Rubber Co., Ltd.) 202, for example. Z9001, refractive index 1.59, ultraviolet irradiation with 1 J / cm 2) can be transferred.
[0040]
The lens array 200 of the liquid crystal display device of Example 1 includes a plurality of lenses 201 having a lens pitch P3 = lens width Pw of 0.1 mm, a lens height Rh of 0.04 mm, and a focal length f = 0.087 mm. A lens array 200 was formed.
[0041]
Furthermore, by forming an antireflection film (light shielding layer) 203 made of, for example, a black resin on the surface of the lens 201 on the liquid crystal display panel 100a side, reflection on the surface of the lens 201 can be prevented. Specifically, an ultraviolet curable resin in which a black pigment was dispersed was spin-coated and cured by 1.5 J / cm 2 ultraviolet irradiation. The thickness of the antireflection film 203 was set to 0.005 mm so that the transmittance of the lens array 200 was 70%.
[0042]
Each lens of the lens array 200 shown in FIG. 2 is a lenticular lens extending in a direction orthogonal to the d3 direction, and is regularly arranged in the d3 direction. The d3 direction forms an angle of 8 ° (θ2 = 8 °) with respect to the d2 direction. As described above, since the periodic directions d1 and d2 of the plurality of picture elements of the liquid crystal display panel and the periodic directions d3 of the plurality of lenses of the lens array intersect with each other, generation of moire fringes due to interference is suppressed.・ Prevented. In addition, since a specific positional relationship is not required between the picture element and the lens, high-precision control of the picture element pitch and the lens pitch and high bonding accuracy are not required.
[0043]
Here, a method of defining the tilt angle that defines the relationship between the periodic direction of the picture element and the periodic direction of the lens will be described. The inclination angle θ1 formed by the d1 direction and the d3 direction and the inclination angle θ2 formed by the d2 direction and the d3 direction are defined so that the respective inclination angles are smaller than 90 °. That is, the d1, d2, and d3 directions can be independently defined as directions different from the directions indicated by arrows in FIG. 2A by 180 °, but the inclination angles θ1 and θ2 are 90 ° or less. Select to define as the angle. The definitions of the d1 direction and the d2 direction are arbitrary, and the column direction may be the d1 direction and the row direction may be the d2 direction.
[0044]
The angle (θ2) formed by the periodic direction of the picture element (d2 direction) and the periodic direction of the lens (d3 direction) is not limited to 8 °. Regarding the 20-inch liquid crystal display panel of Example 1 described above, the occurrence of moire fringes in a liquid crystal display device obtained by arranging the lens array 200 having a different lens pitch P3 with various inclination angles θ2 was visually evaluated. . The results obtained are shown in Table 1 (first column).
[0045]
[Table 1]

As shown in Table 1, with the configuration of specific example 1 (lens pitch 0.1 mm), it is possible to substantially prevent the occurrence of moire fringes when the inclination angle θ2 is in the range of 5 ° to 85 °. In addition, when a lens having a pitch of 0.11 mm is used in the configuration of the first specific example, the generation of moire fringes can be substantially prevented when the inclination angle θ2 is in the range of 6 ° to 84 °. As described above, when the lens pitch changes, the tilt angle range in which the generation of moire fringes can be suppressed changes. Further, when the lens pitch is 0.14 mm, the range of the inclination angle θ2 in which moire fringes are not substantially generated is discontinuous. For example, on the side where the inclination angle θ2 is small, the generation of moire fringes is substantially prevented at 6 ° to 10 ° and 20 ° to 25 °, but the moire is within a range of 10 ° to 20 ° (not including both ends). Generation of stripes is confirmed. As described above, the condition for suppressing the generation of moire fringes greatly depends on the lens pitch and the inclination angle.
[0046]
The width of the tilt angle range that can substantially prevent the occurrence of moire fringes is at least 4 ° (inclination angle of 6 ° to 10 °) when a lens with a pitch of 140 mm is used in the configuration of Example 1, for example. Is obtained. Therefore, the accuracy of the tilt angle required in the step of bonding the liquid crystal cell and the lens array so as to have a relative arrangement within a predetermined tilt angle range is ± 2 °, which can be sufficiently realized with the existing process accuracy.
[0047]
Table 1 shows the results of examining the relationship between the generation of moire fringes and the inclination angle θ2 for another liquid crystal display device (specific example 2). Specific example 2 is a liquid crystal cell having a diagonal size of 18 inches, horizontal arrangement of 1240 horizontal picture elements (1240 for each of R, G, and B), vertical picture element count of 960, and picture element pitch (horizontal direction Ph is 0). 095 mm, vertical direction Pv is 0.286 mm). As is clear from the comparison between specific example 1 and specific example 2 in Table 1, when the periodic structure of the liquid crystal cell changes, the range of the inclination angle θ2 that can suppress the occurrence of moire fringes is the same even if the periodic structure of the lens array is the same. Different.
[0048]
As described above, the range of the inclination angle θ2 for suppressing the generation of moire fringes greatly depends on the periodic structure of the liquid crystal cell and the periodic structure of the lens array. Although it is difficult to generalize the conditions that can suppress the occurrence of moiré fringes, that is, the relationship between each periodic structure (pixel pitch, lens pitch) and the tilt angle, using mathematical formulas, the occurrence of moiré fringes is suppressed. The range of possible tilt angles θ2 (θ2> 0) can be easily found experimentally. In addition, since the range of the inclination angle θ2 (θ2> 0) that can suppress the occurrence of moire fringes is several degrees (in the example shown in Table 1, at least 4 °), in the bonding process between the liquid crystal cell and the lens array The alignment accuracy is in a range that can be sufficiently realized by the current process.
[0049]
In order to suppress the occurrence of moiré fringes, it is preferable to set the picture element and the lens so that they do not have a one-to-one correspondence over the entire display surface (in the d2 direction), and the relationship of P3 · cos θ2 ≦ P2 It is preferable to satisfy Considering the uniformity on the display surface, it is preferable that P3 · cos θ2 ≦ P2 / 2, more preferably P3 · cos θ2 ≦ P2 / 6. However, if P3 is not too small, the lens width Pw also becomes small and it becomes difficult to form a lens array (due to a decrease in accuracy, etc.). Therefore, P3 is preferably about 10 μm or more, but there is no particular limitation. .
[0050]
Next, FIG. 3 shows the result of examining the viewing angle characteristics of the liquid crystal display device of the first embodiment. FIG. 3 is a graph showing the viewing angle dependence of the liquid crystal display device of Example 1 (tilt angle 8 °; lens pitch 0.1 mm), and the horizontal axis is the viewing angle (angle formed between the normal to the display surface and the viewing direction). The vertical axis indicates the contrast ratio. The viewing angle is expressed as 6 o'clock direction (lower side) in the display surface as positive (right side of the graph) and 12 o'clock direction (upper side) as negative (left side of the graph). That is, FIG. 3 shows the viewing angle dependency in the direction in which the viewing angle is desired to be widened by the lens. For comparison, FIG. 3 shows the viewing angle characteristics of a conventional TN mode liquid crystal display device (comparative example) in which no lens array is provided.
[0051]
As is apparent from FIG. 3, the viewing angle dependency of the liquid crystal display device of Example 1 is significantly smaller than the viewing angle dependency of the liquid crystal display device of the comparative example, and a wide viewing angle range (viewing angle range ± 80 °). ), A high contrast ratio (CR ≧ 10) is realized. When the tilt angle θ2 increases, the direction in which the viewing angle spreads by the lens deviates from the direction in which the viewing angle is originally desired to be widened. Therefore, if the tilt angle becomes too large, the desired viewing angle characteristics may not be obtained. It was experimentally confirmed that if the inclination angle θ2 is 30 ° or less, the display observation is not affected. Therefore, in consideration of the dependency of the viewing angle on the azimuth angle (direction in the display surface), the range of the inclination angle θ2 is preferably a range that suppresses the generation of moire fringes and is 30 ° or less. Note that the viewing angle characteristics required for the liquid crystal display device depend on the use of the liquid crystal display device, and therefore the tilt angle range (particularly the upper limit value) may be outside the above range.
[0052]
In the above-described specific example, a configuration in which a lens array having a lenticular lens is disposed in a liquid crystal cell having stripe-arranged picture elements is illustrated, but the present invention is not limited to these. For example, as shown in FIG. 4, a lens (lens) that is periodically arranged at a pitch P4 in the d4 direction orthogonal to the d3 direction in FIG. 2 and has a lens function with respect to light incident from the plane including the d4 direction. The width Pw ′) may be used. In this case, in order to suppress / prevent the generation of moire fringes caused by interference between the periodic structure (pitch P1) in the d1 direction of the liquid crystal cell and the periodic structure (pitch P4) in the d4 direction of the lens array, θ4> It is preferable that the relationship P4 · cos θ3 ≦ P1 is satisfied so that there is no one-to-one correspondence between the picture element and the lens in the d1 direction over the entire display surface. In consideration of the uniformity on the display surface, it is preferable that P4 · cos θ3 ≦ P1 / 2, more preferably P4 · cos θ3 ≦ P1 / 6, as described above. However, if P4 is not too small, the lens width Pw ′ also becomes small and it becomes difficult to form a lens array (due to a decrease in accuracy, etc.). Therefore, P4 is preferably about 10 μm or more, but there is a particular limitation. No. Further, as described above, since the azimuth angle dependency of the viewing angle characteristic increases when the tilt angle is large, the tilt angle θ3 is preferably 30 ° or less.
[0053]
As described above, according to the present embodiment, even in the configuration in which the lens array is bonded to the liquid crystal display panel via the adhesive layer, the generation of moire fringes can be effectively suppressed / prevented. It is possible to provide a wide viewing angle liquid crystal display device capable of achieving the above. It goes without saying that the occurrence of moire fringes can be suppressed / prevented even if the present embodiment is applied to a structure in which the lens array and the liquid crystal display panel are bonded to each other without using an adhesive layer, for example, at the periphery.
[0054]
( reference Embodiment 2)
In FIG. reference FIG. 4 is a schematic cross-sectional view of a transmissive liquid crystal display device 500 of Embodiment 2. The liquid crystal display device 300 includes a liquid crystal display panel 100a, a surface light source 101 that irradiates light to the liquid crystal display panel 100a, and a lens array 503. Since the liquid crystal display panel 100a and the surface light source 101 are the same as those of the liquid crystal display device 100 of the first embodiment, the respective constituent elements are denoted by the same reference numerals, and description thereof is omitted here. Further, in the liquid crystal display device 500, an adhesive layer (106 in FIG. 1) is not used for joining the lens array 503 and the liquid crystal display panel 100a. The liquid crystal display panel 100a and the lens array 603 are bonded using an adhesive or the like at the peripheral portions of the liquid crystal display panel 100a and the lens array 603 (not shown).
[0055]
Book reference In the liquid crystal display device 500 of the embodiment, the lens 603a of the lens array 603 is disposed so as to have a focal point on the opposite side of the surface light source 101 with respect to the picture element of the liquid crystal display panel 100a. If the liquid crystal display panel 100a and the lens array 503 are joined together without using an adhesive layer as in the first embodiment, moire fringes are relatively difficult to observe. By arranging the lens of the lens array so as to have a focal point on the opposite side of the surface light source 101 with respect to the picture element of the liquid crystal display panel 100a and combining with the configuration of the first embodiment, the generation of moire fringes can be more efficiently generated. Can be prevented.
[0056]
Hereinafter, an example in which the inclination angle of the periodic structure of the lens array with respect to the periodic structure of the picture element is 0 ° will be described.
[0057]
FIG. 6 is a schematic diagram for explaining the relationship between the arrangement of the picture elements of the liquid crystal display panel 100a and the arrangement of the lenses 601 of the lens array 600 (an example of the lens array 603 in FIG. 5). 6A is a top view, and FIG. 6B is a cross-sectional view along the d3 direction (pitch P3 direction) of FIG. 6A.
[0058]
The lens array 600 has a plurality of lenticular lenses 603 regularly arranged at a pitch P3 (= lens width Pw). This periodic direction d3 is the same as the period P2 (Pv) of the pixel column direction d2 (the inclination angle is zero degree).
[0059]
As the liquid crystal display device of specific example 3, the lens pitch (P3) is 0.14 mm, the lens height Rh is 0.04 mm, and the focal point is different from the liquid crystal display panel 100a (20 inches) used in specific example 1 of the first embodiment. A lens array having a convex lens with a distance f of 0.14 mm was used. In the liquid crystal display device of the specific example 3, the air conversion distance da from the lens array to the picture element is 0.66 mm (0.7 / 1.52 + 0.3 / 1.52), and the focal length f (= 0). .14) is shorter than the air equivalent distance da (= 0.66 mm) from the lens array to the picture element. Accordingly, the light transmitted through the picture element is diffused by the lens, and the image formed by the plurality of picture elements is blurred, so that the periodic structure of the picture element becomes inconspicuous, and as a result, the generation of moire fringes is suppressed. The lower limit value of the focal length f of the lens is Pw / {2 · (nl−1)} where the lens width is Pw and the refractive index is n1. In order to make the focal length f shorter than this, it is necessary to form a lens having a lens height larger than the width of the lens, which makes it difficult to form the lens.
[0060]
The result of having evaluated the generation | occurrence | production of a moire fringe by changing a focal distance in the structure of the specific example 3 is shown.
[0061]
[Table 2]

In Table 2, “x” indicates that the period of moire fringes was observed with a width of 0.5 mm or more and a decrease in display quality was observed, and “Δ” indicates that the period of moire fringes was 0.3 mm to 1.0 mm. Observed by the width, it indicates that the display quality is slightly reduced, and ◯ indicates that the period of moire fringes is 0.09 mm or less and the display quality is not decreased. Note that a liquid crystal display device having an evaluation result of Δ can be used depending on the application.
[0062]
As is apparent from the results in Table 2, it can be seen that when the focal length f is substantially equal to the air conversion distance da, moire fringes are observed and the display quality is deteriorated. From Table 2, it can be seen that the focal length f is preferably 0.5 mm or less, that is, about 0.75 times or less the air equivalent distance da. The focal length f of the lens of the lens array may be set as appropriate so as to satisfy the above conditions according to the air conversion distance da (the thickness, refractive index, etc. of the color filter substrate) of the liquid crystal display panel 100a to be used.
[0063]
FIG. 7 shows the viewing angle characteristics of the liquid crystal display device of Example 3. FIG. 7 is a graph showing the viewing angle characteristics similar to those in FIG. 3, and the viewing angle characteristics of the same liquid crystal display device as that of the comparative example of the first embodiment are also shown for comparison. As apparent from FIG. 7, the viewing angle dependency of the liquid crystal display device of the specific example 3 is significantly smaller than the viewing angle dependency of the liquid crystal display device of the comparative example, and a wide viewing angle range (viewing angle range ± 80 °). ), A high contrast ratio (CR ≧ 10 °) is realized.
[0064]
Book reference The lens array used in the liquid crystal display device of the embodiment is not limited to the above example. Of course, if the focal length satisfies the above relationship, a lens having a lens function in the d4 direction orthogonal to the d3 direction may be used as described in the first embodiment with reference to FIG.
[0065]
Further, as shown in FIG. 6C, a plurality of concave lenses 701 can be used instead of the lens array 600 shown in FIG. For example, by setting the pitch P3 of the concave lenses 701 to 0.14 mm and the height Rh to −0.04 mm, display characteristics equivalent to those of the specific example 3 can be obtained. Since the concave lens 701 has a focal point on the viewer side, it has the effect of blurring the image of the picture element of the liquid crystal display panel 100a, and therefore has the effect of suppressing / preventing the occurrence of moire fringes.
[0066]
The lens array 600 having the concave lens 701 can be manufactured, for example, by the following method. An acrylic resin plate having a plurality of convex portions is formed by injection molding of an acrylic resin using a master mold having a plurality of concave portions having a predetermined shape. A nickel layer is formed on the surface of the acrylic resin plate using an electroforming method to obtain a mold. This nickel layer improves the surface hardness of the mold. Next, an ultraviolet curable resin (for example, Z9001 manufactured by Nippon Synthetic Rubber Co., Ltd .; refractive index 1.59) is dropped on the mold and irradiated with ultraviolet rays (for example, about 1.0 J / cm 2) to cure the ultraviolet rays. The resin is cured to obtain a lens array in which a concave portion having a predetermined shape is transferred and formed on a lens sheet substrate (for example, Arton film manufactured by Nippon Synthetic Rubber Co., Ltd.).
[0067]
Embodiment 1 described above And Reference Embodiment 2 In the above, the present invention has been described by taking a liquid crystal display device using a TN liquid crystal display panel as an example, but a liquid crystal display panel of another display mode such as an STN type or an ECB mode can be used. Further, the arrangement of picture elements is not limited to the stripe arrangement, and a liquid crystal display panel having picture elements in a delta arrangement may be used. In addition, the direction in which the viewing angle is enlarged by the lens may be appropriately set in consideration of the display mode of the liquid crystal display panel to be used, the arrangement of the polarizing plates, and the like. Moreover, the manufacturing method of a lens array is not restricted to the illustrated method, It can manufacture by a well-known method. In addition, if the illustrated method is used, the lens array of this invention can be manufactured efficiently.
[0068]
【The invention's effect】
According to the present invention, the periodic direction of the plurality of picture elements of the liquid crystal display panel of the liquid crystal display device and the periodic direction of the plurality of lenses of the lens array are arranged so as to intersect with each other. It is suppressed. Also, Although the lens array and the liquid crystal display panel are bonded together via an adhesive layer that contacts a part of the lens, the occurrence of moire fringes can be suppressed / prevented. further, Since a specific positional relationship is not required between the picture element and the lens, high-precision control of the picture element pitch and lens pitch and high bonding accuracy are not required, and it is manufactured by a conventional process using a conventional manufacturing apparatus. can do.
[0069]
Thus, according to the present invention, there is provided a liquid crystal display device with excellent display quality, which has excellent viewing angle characteristics and suppresses / prevents the generation of moire fringes. The present invention is particularly suitably applied to a large direct-view liquid crystal display device.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a transmissive liquid crystal display device 100 according to a first embodiment of the present invention.
2 is a schematic diagram for explaining the relationship between the arrangement of picture elements of a liquid crystal display panel and the arrangement of lenses of a lens array in the liquid crystal display device 100 of Embodiment 1. FIG.
3 is a graph showing viewing angle characteristics of the liquid crystal display device of Embodiment 1. FIG.
4 is a cross-sectional view (a cross-sectional view along a direction orthogonal to FIG. 2B) of a lens array used in the present invention. FIG.
FIG. 5 is according to the present invention. reference 6 is a schematic cross-sectional view of a transmissive liquid crystal display device 500 of Embodiment 2. FIG.
[Fig. 6] reference FIG. 10 is a schematic diagram for explaining a relationship between an arrangement of picture elements of a liquid crystal display panel and an arrangement of lenses of a lens array in the liquid crystal display device 500 of Embodiment 2.
[Fig. 7] reference 6 is a graph showing viewing angle characteristics of the liquid crystal display device of Embodiment 2.
[Explanation of symbols]
100, 500 liquid crystal display device
100a liquid crystal display panel
101 Surface light source
102a, 102b Polarizing element
103, 200, 503, 600, 700 Lens array
104a, 104b substrate
105 Liquid crystal layer
105a Sealant

Claims (7)

A liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates and a pair of polarizing elements disposed so as to sandwich the liquid crystal layer, a surface light source for irradiating the liquid crystal display panel with light, and the liquid crystal display A liquid crystal display device comprising a lens array disposed on the opposite side of the surface light source of the panel,
The liquid crystal display panel includes a plurality of picture elements regularly arranged at a first pitch (P1) in a first direction and at a second pitch (P2) in a second direction intersecting the first direction. And the lens array is regularly arranged in a third direction at a third pitch (P3), and has a function of changing a traveling direction of light incident from within a plane including the third direction. The periodic structure of the plurality of lenses and the periodic structure of the picture element of the liquid crystal display panel do not interfere with each other, and the third direction intersects the first and second directions. It is,
The liquid crystal display device further includes an adhesive layer that joins the lens array and one of the pair of polarizing elements, and the adhesive layer is in contact with a part of a surface of each lens of the plurality of lenses . The second angle (θ2) between the third direction and the second direction is the same as the first angle (θ1) between the third direction and the first direction, or Small (θ2 ≦ θ1), and
2. The liquid crystal display device according to claim 1, wherein the third pitch (P3) satisfies the relationship of P3 · cos θ2 ≦ P2 with the second pitch (P2). 3. The liquid crystal display device according to claim 1, wherein each of the plurality of lenses is a lenticular lens extending in a fourth direction orthogonal to the third direction. The plurality of lenses are regularly arranged at a fourth pitch (P4) in a fourth direction orthogonal to the third direction and forming a third angle (θ3) with the first direction, Further having a function of changing the traveling direction of light incident from within the plane including the direction of four, and
The liquid crystal display device according to claim 2, wherein the fourth pitch (P4) satisfies the relationship of the first pitch (P1) and P4 · cos θ3 ≦ P1. 5. The liquid crystal display device according to claim 1, wherein a second angle θ <b> 2 formed by the third direction and the second direction is 30 ° or less. Wherein the plurality of lenses, the liquid crystal display device according to any one of 5 from the liquid crystal display wherein the plurality of claim 1 which is arranged to have a focal point on the opposite side to the surface light source with respect to the picture elements of the panel . Each of the plurality of lenses is a convex lens having a focal length f, a lens width Pw, and a refractive index nl.
An air conversion distance da from the surface on which the plurality of lenses are formed to the surface on which the plurality of picture elements are formed satisfies the relationship Pw / {2 · (nl−1)} ≦ f <da. The liquid crystal display device according to claim 6 .

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