JPH11125717A - Polarizing element, polarized light source device and liquid crystal display device - Google Patents
Polarizing element, polarized light source device and liquid crystal display deviceInfo
- Publication number
- JPH11125717A JPH11125717A JP9309407A JP30940797A JPH11125717A JP H11125717 A JPH11125717 A JP H11125717A JP 9309407 A JP9309407 A JP 9309407A JP 30940797 A JP30940797 A JP 30940797A JP H11125717 A JPH11125717 A JP H11125717A
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- JP
- Japan
- Prior art keywords
- liquid crystal
- polarized light
- layer
- crystal polymer
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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- Liquid Crystal (AREA)
- Polarising Elements (AREA)
Abstract
Description
【０００１】[0001]
【発明の技術分野】本発明は、光利用効率に優れる偏光
光源装置や明るさに優れて良視認性の液晶表示装置等を
形成しうる偏光素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing element capable of forming a polarized light source device excellent in light use efficiency and a liquid crystal display device excellent in brightness and good visibility.
【０００２】[0002]
【背景技術】従来、側面からの入射光を上下面の片側よ
り出射させるようにしたサイドライト型の導光板の下面
に反射層を設け、出射面にコレステリック液晶層からな
る円偏光分離層を設けて、その円偏光分離層を介し入射
光を左右の円偏光からなる透過光と反射光に分離し、そ
の反射光を下面の反射層を介し反射させて出射面より再
出射させるようにした照明システムが提案されていた
（特開平３−４５９０６号公報、特開平６−３２４３３
３号公報、特開平７−３６０３２号公報）。2. Description of the Related Art Conventionally, a reflection layer is provided on the lower surface of a side light type light guide plate that allows incident light from the side to be emitted from one of upper and lower surfaces, and a circularly polarized light separating layer made of a cholesteric liquid crystal layer is provided on the emission surface. An illumination device that separates incident light into left and right circularly polarized transmitted light and reflected light through the circularly polarized light separating layer, reflects the reflected light through the lower reflective layer, and emits the reflected light again from the emission surface. A system has been proposed (JP-A-3-45906, JP-A-6-32433).
No. 3, JP-A-7-36032).
【０００３】かかる照明システムは、非偏光の通例光で
は偏光板を透過する際に導光板出射光の５５％程度が吸
収されて有効利用できる光に乏しいことから、光を偏光
として供給できるようにして偏光板による吸収ロスを防
止し、光の利用効率を向上して液晶表示装置等の輝度の
向上や消費電力の低減を図りうるようにしたものであ
る。[0003] Such an illumination system is capable of supplying light as polarized light because non-polarized ordinary light absorbs about 55% of the light emitted from the light guide plate when transmitted through the polarizer, and thus is scarcely available light. Thus, absorption loss due to a polarizing plate is prevented, light utilization efficiency is improved, and luminance of a liquid crystal display device or the like can be improved and power consumption can be reduced.
【０００４】前記においては通例、円偏光分離層の上に
１／４波長板を設けて、円偏光分離層より出射した円偏
光を１／４波長板を介し直線偏光化し、それにより偏光
板による吸収ロスをより低減する方策が採られている。
すなわちコレステリック液晶層ではその厚さを増すこと
で偏光度（円偏光二色性）を高めうるが、それには理論
上限界のあることが指摘されている。[0004] In the above, usually, a quarter-wave plate is provided on the circularly polarized light separating layer, and the circularly polarized light emitted from the circularly polarized light separating layer is linearly polarized through the quarter wave plate, whereby the polarizing plate is used. Measures have been taken to further reduce absorption losses.
That is, in the cholesteric liquid crystal layer, the degree of polarization (circular dichroism) can be increased by increasing its thickness, but it has been pointed out that this has a theoretical limit.
【０００５】すなわち二次以上の反射を無視した理論上
の概略計算では、例えば平均屈折率が１．５で左捩じれ
のコレステリック液晶層に左円偏光が入射すると、左円
偏光の９２％と右円偏光の４％が反射され、右円偏光の
４％が透過する。また右円偏光が入射すると、左円偏光
の４％が反射され、右円偏光の９２％と左円偏光の４％
が透過する。従って偏光度は、９１．７％｛（９２−
４）／（９２＋４）｝となり、これが限界となる。That is, in a theoretical rough calculation ignoring the second-order or higher reflection, for example, when left-handed circularly polarized light is incident on a cholesteric liquid crystal layer having an average refractive index of 1.5 and twisting leftward, 92% of the left-handed circularly polarized light becomes 92% of the right-handed circularly polarized light. 4% of the circularly polarized light is reflected and 4% of the right circularly polarized light is transmitted. When right circular polarized light enters, 4% of left circular polarized light is reflected, and 92% of right circular polarized light and 4% of left circular polarized light are reflected.
Is transmitted. Therefore, the degree of polarization is 91.7% ｛(92−
4) / (92 + 4)}, which is the limit.
【０００６】一方、前記において、１／４波長板を介し
コレステリック液晶層の出射光を直線偏光に変換した場
合、コレステリック液晶層を透過する左円偏光に基づく
右円偏光の４％、及び右円偏光に基づく右円偏光の９２
％と左円偏光の４％とで１００％の偏光度となる（透過
率４８％）。On the other hand, in the above, when the light emitted from the cholesteric liquid crystal layer is converted into linearly polarized light via the quarter-wave plate, 4% of the right circularly polarized light based on the left circularly polarized light transmitted through the cholesteric liquid crystal layer and the right circularly polarized light. 92 of right circular polarization based on polarization
% And 4% of the left circularly polarized light, the degree of polarization is 100% (transmittance: 48%).
【０００７】しかしながら、実際上の円偏光分離層は通
例１mm以下、就中１〜１００μm程度のコレステリック
液晶ポリマー層にて形成され、従ってコレステリック液
晶層の厚さ不足のためか１／４波長板を介した場合にも
８５％程度の偏光度としかならない問題点があった。コ
レステリック液晶ポリマー層の厚さを増やすことは、配
向処理や配向精度等の点より困難である。However, the practical circularly polarized light separating layer is usually formed of a cholesteric liquid crystal polymer layer of 1 mm or less, especially about 1 to 100 μm. However, there is a problem that the degree of polarization is only about 85%. It is difficult to increase the thickness of the cholesteric liquid crystal polymer layer from the viewpoint of alignment treatment and alignment accuracy.
【０００８】[0008]
【発明の技術的課題】本発明は、コレステリック液晶ポ
リマー層の厚さが１〜１０μm程度と薄い場合にも、円
偏光分離層と１／４波長板を介して９５％を超える高い
偏光度の直線偏光を得ることができる偏光素子を開発し
て、輝度や視認性に優れる偏光光源装置や液晶表示装置
を得ることを課題とする。SUMMARY OF THE INVENTION The present invention is directed to a method for producing a cholesteric liquid crystal polymer layer having a high degree of polarization exceeding 95% through a circularly polarized light separating layer and a quarter wavelength plate even when the thickness of the cholesteric liquid crystal polymer layer is as thin as about 1 to 10 μm. An object of the present invention is to develop a polarizing element capable of obtaining linearly polarized light and to obtain a polarized light source device and a liquid crystal display device having excellent brightness and visibility.
【０００９】[0009]
【課題の解決手段】本発明は、１層又は２層以上のコレ
ステリック液晶ポリマー層からなる円偏光分離層の上
に、前記コレステリック液晶ポリマー層の平均屈折率ｎ
に対し屈折率がｎ±０．２の接着層を介して１／４波長
板を有してなり、必要に応じ１／４波長板側のコレステ
リック液晶ポリマー層の表面における液晶ポリマーが無
配向状態にあることを特徴とする偏光素子、及び側面か
らの入射光を上下面の一方より出射する導光板の光出射
側に前記の偏光素子を有することを特徴とする偏光光源
装置、並びにその偏光光源装置の光出射側に液晶セルを
有することを特徴とする液晶表示装置を提供するもので
ある。According to the present invention, an average refractive index n of the cholesteric liquid crystal polymer layer is provided on a circularly polarized light separating layer composed of one or more cholesteric liquid crystal polymer layers.
The liquid crystal polymer on the surface of the cholesteric liquid crystal polymer layer on the side of the quarter wave plate, if necessary, in a non-aligned state. And a polarization light source device comprising the polarization element on the light exit side of a light guide plate that emits incident light from the side surface from one of the upper and lower surfaces, and a polarization light source thereof. An object of the present invention is to provide a liquid crystal display device having a liquid crystal cell on the light emission side of the device.
【００１０】[0010]
【発明の効果】本発明によれば、薄いコレステリック液
晶ポリマー層からなる円偏光分離層の場合にも１／４波
長板を介して高い偏光度の直線偏光を出射する偏光素子
が得られ、光利用効率に優れて輝度に優れる偏光光源装
置及び明るくて視認性に優れる液晶表示装置を得ること
ができる。また１／４波長板側表面の液晶ポリマーが無
配向状態にある場合には、より輝度に優れて表示ムラが
少なく、斜視方向の色変化や色ムラも少なくて良視認の
視野角に優れる液晶表示装置が得られる。According to the present invention, even in the case of a circularly polarized light separating layer composed of a thin cholesteric liquid crystal polymer layer, a polarizing element which emits linearly polarized light having a high degree of polarization through a quarter wavelength plate can be obtained. A polarized light source device excellent in use efficiency and excellent in luminance and a liquid crystal display device bright and excellent in visibility can be obtained. In addition, when the liquid crystal polymer on the surface of the quarter-wave plate side is in a non-aligned state, the liquid crystal is more excellent in brightness, has less display unevenness, has less color change and color unevenness in the oblique direction, and has an excellent viewing angle for good visibility. A display device is obtained.
【００１１】前記の輝度向上効果は、特定の屈折率から
なる接着層を介した円偏光分層と１／４波長板との密着
処理に基づく。すなわち本発明者らは、上記の偏光度を
高めるために鋭意研究を重ねた結果、コレステリック液
晶ポリマー層の厚さが薄い場合の透過円偏光は、楕円化
しており、その楕円偏光の向きは、液晶ポリマー層の出
射側表面の液晶ポリマー（メソゲン）の配向方向に依存
していて、前記接着層を介することで楕円偏光を効率よ
く円偏光化して１／４波長板に供給しうることを究明し
た。The above-mentioned brightness improving effect is based on the adhesion treatment between the circularly polarized light separating layer and the quarter-wave plate via an adhesive layer having a specific refractive index. That is, the present inventors have conducted intensive studies to increase the degree of polarization described above, and as a result, when the thickness of the cholesteric liquid crystal polymer layer is thin, the transmitted circularly polarized light is elliptical, and the direction of the elliptically polarized light is It depends on the orientation direction of the liquid crystal polymer (mesogen) on the exit side surface of the liquid crystal polymer layer, and it is determined that the elliptically polarized light can be efficiently converted into circularly polarized light and supplied to the quarter-wave plate through the adhesive layer. did.
【００１２】従って輝度の向上は、１／４波長板への円
偏光性に優れる光の供給による偏光度の向上で光の有効
利用効率が向上したことに基づくと考えられる。また光
の有効利用効率の向上の点では、接着層の屈折率に基づ
く界面での反射ロスの低減も寄与していると考えられ
る。Therefore, it is considered that the improvement in the luminance is based on the improvement in the degree of polarization by the supply of light having excellent circular polarization to the quarter-wave plate, thereby improving the effective use efficiency of light. Further, in terms of improving the effective use efficiency of light, it is considered that the reduction of reflection loss at the interface based on the refractive index of the adhesive layer also contributes.
【００１３】一方、斜視方向の色変化や色ムラを含む表
示ムラの低減の効果は、ランダムに配向した表面の液晶
ポリマーによる色バランスの調節機能に基づく。すなわ
ち前記の如く液晶ポリマー層出射光の楕円偏光化によ
り、波長毎にその方位角や楕円率が相違することとな
り、１／４波長板を介した場合に偏光度が波長毎に異な
ることとなって液晶セルに適用した場合に色バランスが
崩れ、表示の着色化等でニュートラル性が低下する。On the other hand, the effect of reducing display unevenness including color change and color unevenness in the oblique direction is based on the function of adjusting the color balance by the liquid crystal polymer on the randomly oriented surface. That is, as described above, the azimuthal polarization of the light emitted from the liquid crystal polymer layer causes the azimuthal angle and the ellipticity to differ for each wavelength, and the degree of polarization differs for each wavelength when passing through a quarter-wave plate. When applied to a liquid crystal cell, the color balance is lost, and the neutral property is reduced due to coloring of the display.
【００１４】しかし前記の場合に、液晶ポリマーがラン
ダムに配向した表面を介して光を出射させることによ
り、前記した液晶ポリマーの配向方向に依存した楕円偏
光化による波長毎の方位角や楕円率のバラツキを抑制で
き、１／４波長板を介した場合に広い波長域で偏光度を
一定化できて液晶セルに適用した場合の色バランスの崩
れを抑制でき、偏光素子不使用の場合とほぼ同じニュー
トラルな色相を実現できて斜視方向の色ムラ等の発生が
抑制されると共に、光の有効利用効率の向上で輝度も向
上する。However, in the above case, by emitting light through the surface where the liquid crystal polymer is randomly oriented, the azimuthal angle and ellipticity of each wavelength by the elliptically polarized light depending on the orientation direction of the liquid crystal polymer described above. Variation can be suppressed, the degree of polarization can be kept constant over a wide wavelength range through a quarter-wave plate, and the color balance when applied to a liquid crystal cell can be suppressed. This is almost the same as when a polarizing element is not used. A neutral hue can be realized, and the occurrence of color unevenness in the oblique direction can be suppressed, and the luminance can be improved by improving the effective use efficiency of light.
【００１５】[0015]
【発明の実施形態】本発明の偏光素子は、１層又は２層
以上のコレステリック液晶ポリマー層からなる円偏光分
離層の上に、前記コレステリック液晶ポリマー層の平均
屈折率ｎに対し屈折率がｎ±０．２の接着層を介して１
／４波長板を有してなり、必要に応じ１／４波長板側の
コレステリック液晶ポリマー層の表面における液晶ポリ
マーが無配向状態にあるものからなる。その例を図１、
図２に示した。１が円偏光分離層、２が接着層、３が１
／４波長板である。BEST MODE FOR CARRYING OUT THE INVENTION The polarizing element of the present invention has a refractive index of n with respect to the average refractive index n of the cholesteric liquid crystal polymer layer on a circularly polarized light separating layer comprising one or more cholesteric liquid crystal polymer layers. 1 through an adhesive layer of ± 0.2
It has a 波長 wavelength plate, and if necessary, the liquid crystal polymer on the surface of the cholesteric liquid crystal polymer layer on the 波長 wavelength plate side is in a non-aligned state. An example is shown in FIG.
As shown in FIG. 1 is a circularly polarized light separating layer, 2 is an adhesive layer, 3 is 1
/ 4 wavelength plate.
【００１６】円偏光分離層は、グランジャン配向により
自然光を透過光と反射光として左右の円偏光に分離する
適宜なコレステリック液晶ポリマーの１種又は２種以上
を用いて形成しうる。従ってコレステリック液晶ポリマ
ーとしては、液晶配向性を付与する共役性の直線状原子
団（メソゲン）がポリマーの主鎖や側鎖に導入された主
鎖型や側鎖型などの種々のものを用いうる。The circularly polarized light separating layer can be formed by using one or more appropriate cholesteric liquid crystal polymers that separate natural light into left and right circularly polarized light as transmitted light and reflected light by means of Grandian orientation. Therefore, as the cholesteric liquid crystal polymer, various types such as a main chain type or a side chain type in which a conjugated linear atomic group (mesogen) imparting liquid crystal orientation is introduced into a main chain or a side chain of the polymer can be used. .
【００１７】複屈折率差の大きいコレステリック液晶ポ
リマーほど円偏光二色性の波長域が広くなり、大視野角
時の波長シフトに対する余裕などの点より好ましく用い
うる。また液晶ポリマーとしては、取扱い性や実用温度
での配向の安定性などの点より、ガラス転移温度が３０
〜１５０℃のものが好ましく用いうる。A cholesteric liquid crystal polymer having a larger birefringence difference has a wider wavelength range of circular dichroism, and can be preferably used in view of a margin for a wavelength shift at a large viewing angle. The liquid crystal polymer has a glass transition temperature of 30 from the viewpoint of handleability and stability of alignment at a practical temperature.
１５０150 ° C. can be preferably used.
【００１８】ちなみに前記した主鎖型のコレステリック
液晶ポリマーの例としては、屈曲性を付与するスペーサ
部を必要に応じ介してパラ置換環状化合物等からなるメ
ソゲン基を結合した構造を有する、例えばポリエステル
系やポリアミド系、ポリカーボネート系やポリエステル
イミド系などのポリマーがあげられる。Incidentally, examples of the above-mentioned main-chain type cholesteric liquid crystal polymer include a structure in which a mesogen group composed of a para-substituted cyclic compound or the like is bonded via a spacer portion for imparting flexibility, if necessary, such as a polyester-based cholesteric liquid crystal polymer. And polyamide-based, polycarbonate-based and polyesterimide-based polymers.
【００１９】また側鎖型のコレステリック液晶ポリマー
の例としては、ポリアクリレートやポリメタクリレー
ト、ポリシロキサンやポリマロネート等を主鎖骨格と
し、側鎖として共役性の原子団からなるスペーサ部を必
要に応じ介してパラ置換環状化合物等からなる低分子液
晶化合物（メソゲン部）を有するもの、低分子カイラル
剤含有のネマチック系液晶ポリマー、キラル成分導入の
液晶ポリマー、ネマチック系とコレステリック系の混合
液晶ポリマーなどがあげられる。Examples of the side-chain type cholesteric liquid crystal polymer include polyacrylate, polymethacrylate, polysiloxane, polymalonate, and the like having a main chain skeleton and a spacer portion comprising a conjugated atomic group as a side chain, if necessary. And low molecular weight liquid crystal compounds (mesogenic parts) composed of para-substituted cyclic compounds, etc., nematic liquid crystal polymers containing low molecular weight chiral agents, liquid crystal polymers introduced with chiral components, mixed liquid crystal polymers of nematic and cholesteric types, etc. Can be
【００２０】前記の如く、例えばアゾメチン形やアゾ
形、アゾキシ形やエステル形、ビフェニル形やフェニル
シクロヘキサン形、ビシクロヘキサン形の如きパラ置換
芳香族単位やパラ置換シクロヘキシル環単位などからな
るネマチック配向性を付与するパラ置換環状化合物を有
するものにても、不斉炭素を有する化合物等からなる適
宜なキラル成分や低分子カイラル剤等を導入する方式な
どによりコレステリック配向性のものとすることができ
る（特開昭５５−２１４７９号公報、米国特許明細書第
５３３２５２２号等）。なおパラ置換環状化合物におけ
るパラ位における末端置換基は、例えばシアノ基やアル
キル基、アルコキシ基などの適宜なものであってよい。As described above, for example, nematic orientation comprising para-substituted aromatic units and para-substituted cyclohexyl ring units such as azomethine, azo, azoxy, ester, biphenyl, phenylcyclohexane, and bicyclohexane forms can be obtained. Even those having a para-substituted cyclic compound to be imparted can be made to have cholesteric orientation by a method of introducing an appropriate chiral component such as a compound having an asymmetric carbon, a low molecular weight chiral agent, etc. No. 55-21479, U.S. Pat. No. 5,332,522). The terminal substituent at the para position in the para-substituted cyclic compound may be an appropriate one such as a cyano group, an alkyl group, or an alkoxy group.
【００２１】またスペーサ部としては、屈曲性を示す例
えばポリメチレン鎖−（ＣＨ2）n−やポリオキシメチレ
ン鎖−（ＣＨ2ＣＨ2Ｏ）m−などがあげられる。スペー
サ部を形成する構造単位の繰返し数は、メソゲン部の化
学構造等により適宜に決定され、一般にはポリメチレン
鎖の場合にはｎが０〜２０、就中２〜１２、ポリオキシ
メチレン鎖の場合にはｍが０〜１０、就中１〜３であ
る。Examples of the spacer portion include a polymethylene chain — (CH 2 ) n — and a polyoxymethylene chain — (CH 2 CH 2 O) m — which exhibit flexibility. The number of repetitions of the structural unit forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion and the like. In general, in the case of a polymethylene chain, n is 0 to 20, especially 2 to 12, and in the case of a polyoxymethylene chain. Has m of 0 to 10, especially 1 to 3.
【００２２】円偏光分離層の形成は、例えば支持基材上
にポリイミドやポリビニルアルコール、ポリエステルや
ポリアリレート、ポリアミドイミドやポリエーテルイミ
ド等の膜を形成してレーヨン布等でラビング処理した配
向膜、又はＳｉＯ2の斜方蒸着層等からなる適宜な配向
膜を設けてその配向膜の上に、あるいは延伸フィルム等
からなる分子配向性の支持基材の上にコレステリック液
晶ポリマーを展開し、それをガラス転移温度以上、等方
相転移温度未満に加熱し、液晶ポリマー分子がグランジ
ャン配向した状態でガラス転移温度未満に冷却してガラ
ス状態とし、当該配向が固定化された固化層とする方法
などにより行うことができる。The circularly polarized light separating layer may be formed, for example, by forming a film of polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, or the like on a support substrate and rubbing it with a rayon cloth or the like, Or, an appropriate alignment film made of an obliquely deposited layer of SiO 2 or the like is provided, and a cholesteric liquid crystal polymer is developed on the alignment film, or on a molecularly-oriented support base material made of a stretched film or the like. A method in which a liquid crystal polymer molecule is heated to a temperature equal to or higher than the glass transition temperature and lower than the isotropic phase transition temperature, and is cooled to a temperature lower than the glass transition temperature in a state in which the liquid crystal polymer molecules are oriented in a Grand-Jan state to form a solidified layer in which the orientation is fixed. Can be performed.
【００２３】前記の支持基材には、透明なプラスチック
フィルムやガラス板などからなる単層物や複層物等の適
宜なものを用いうる。そのプラスチックについては特に
限定はなく、耐湿性や耐熱性や強度等の使用目的に応じ
た物性などにより適宜に選択することができる。ちなみ
に前記プラスチックの例としては、ポリエチレンやポリ
プロピレンの如きポリオレフィン系、ポリエステル系、
ポリイミド系、ポリカーボネート系、ポリエーテルスル
ホン系、ポリスルホン系、セルロース系、ポリアリレー
ト系、ポリスチレン系、ポリビニルアルコール系、ポリ
塩化ビニル系、ポリ塩化ビニリデン系、ポリアクリル
系、ポリアミド系、エポキシ系、液晶ポリマー系のもの
などがあげられる。As the above-mentioned supporting base material, an appropriate material such as a single-layered product or a multi-layered product made of a transparent plastic film or a glass plate can be used. The plastic is not particularly limited, and can be appropriately selected depending on physical properties according to the intended use such as moisture resistance, heat resistance and strength. Incidentally, examples of the plastic include polyolefins such as polyethylene and polypropylene, polyesters,
Polyimide, polycarbonate, polyethersulfone, polysulfone, cellulose, polyarylate, polystyrene, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyacryl, polyamide, epoxy, liquid crystal polymer And the like.
【００２４】液晶ポリマーの展開は、例えば液晶ポリマ
ーの溶媒による溶液をスピンコート法やロールコート
法、フローコート法やプリント法、ディップコート法や
流延成膜法、バーコート法やグラビア印刷法等の適宜な
方法で薄層展開し、それを必要に応じ乾燥処理する方法
などにより行うことができる。前記の溶媒としては、例
えば塩化メチレンやシクロヘキサノン、トリクロロエチ
レンやテトラクロロエタン、Ｎ−メチルピロリドンやテ
トラヒドロフランなどの適宜なものを用いうる。The liquid crystal polymer can be developed, for example, by applying a solution of the liquid crystal polymer in a solvent by a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, a gravure printing method, or the like. The method can be performed by a method of developing a thin layer by an appropriate method described above and drying it as necessary. Suitable solvents such as methylene chloride, cyclohexanone, trichloroethylene, tetrachloroethane, N-methylpyrrolidone, and tetrahydrofuran can be used as the solvent.
【００２５】また液晶ポリマーの加熱溶融物、好ましく
は等方相を呈する状態の加熱溶融物を前記に準じ展開
し、必要に応じその溶融温度を維持しつつ更に薄層に展
開して固化させる方法などの、溶媒を使用しない方法、
従って作業環境の衛生性等が良好な方法によっても液晶
ポリマーを展開させることができる。Further, a method in which a heated melt of a liquid crystal polymer, preferably a heated melt in a state exhibiting an isotropic phase, is developed in accordance with the above, and, if necessary, further developed into a thin layer and solidified while maintaining the melting temperature. Methods that do not use solvents, such as
Therefore, the liquid crystal polymer can be developed by a method having good work environment hygiene and the like.
【００２６】液晶ポリマーの展開層を配向させるための
加熱処理は、上記した如く液晶ポリマーのガラス転移温
度から等方相転移温度までの温度範囲、すなわち液晶ポ
リマーが液晶相を呈する温度範囲に加熱することにより
行うことができる。また配向状態の固定化は、ガラス転
移温度未満に冷却することで行うことができ、その冷却
条件については特に限定はない。通例、前記の加熱処理
を３００℃以下の温度で行いうることから、自然冷却方
式や急冷方式が一般に採られる。In the heat treatment for orienting the spread layer of the liquid crystal polymer, as described above, the liquid crystal polymer is heated to a temperature range from the glass transition temperature to the isotropic phase transition temperature, that is, to a temperature range in which the liquid crystal polymer exhibits a liquid crystal phase. It can be done by doing. The orientation can be fixed by cooling the glass to a temperature lower than the glass transition temperature, and the cooling conditions are not particularly limited. Usually, since the above-mentioned heat treatment can be performed at a temperature of 300 ° C. or less, a natural cooling system or a rapid cooling system is generally employed.
【００２７】形成するコレステリック液晶ポリマー層
は、可及的に均一に配向していることが好ましい。均一
配向のコレステリック液晶ポリマー層は、散乱のない反
射光を提供して、液晶表示装置等の視野角の拡大に有利
であり、特に斜め方向からも直接観察される直視型液晶
表示装置等の形成に適している。ただし上記した如く、
１／４波長板が配置される側のコレステリック液晶ポリ
マー層の表面においては、液晶ポリマーの配向方向がラ
ンダムな無配向状態にあることが表示ムラの防止等の点
より好ましい。かかる片面が無配向状態のコレステリッ
ク液晶ポリマー層の形成は、配向処理時に片面を空気等
に接触させて配向力を作用させない方式や配向層の再加
熱処理で配向を乱す方式などの適宜な方式で行うことが
できる。The cholesteric liquid crystal polymer layer to be formed is preferably oriented as uniformly as possible. The cholesteric liquid crystal polymer layer having a uniform orientation provides reflected light without scattering, which is advantageous for expanding the viewing angle of a liquid crystal display device and the like, and particularly, for forming a direct-view type liquid crystal display device which can be directly observed even from an oblique direction. Suitable for. However, as mentioned above,
On the surface of the cholesteric liquid crystal polymer layer on the side where the quarter-wave plate is disposed, it is preferable that the alignment direction of the liquid crystal polymer is in a random non-alignment state from the viewpoint of preventing display unevenness and the like. The formation of the cholesteric liquid crystal polymer layer in which one surface is non-aligned is performed by an appropriate method such as a method in which one surface is brought into contact with air or the like during the alignment treatment so that the alignment force is not applied or a method in which the alignment layer is reheated to disturb the alignment. It can be carried out.
【００２８】支持基材上に形成したコレステリック液晶
ポリマー層は、その支持基材に付設したまま、あるいは
支持基材より分離して円偏光分離層の形成に用いうる。
また円偏光分離層を形成するコレステリック液晶ポリマ
ー層は、１層であってもよいし、２層以上であってもよ
い。従って本発明の偏光素子は、図１や図２（ａ）〜
（ｅ）に例示した如く、１層又は２層以上のコレステリ
ック液晶ポリマー層１，１２，１３，１６の適宜な位置
に、単層若しくは複層の支持基材１１，１４，１５を有
する形態又は支持基材を有しない形態の適宜な層形態を
有するものであってよい。The cholesteric liquid crystal polymer layer formed on the supporting substrate can be used for forming a circularly polarized light separating layer while being attached to the supporting substrate or separated from the supporting substrate.
The cholesteric liquid crystal polymer layer forming the circularly polarized light separation layer may be a single layer or two or more layers. Therefore, the polarizing element of the present invention has the structure shown in FIGS.
As shown in (e), one or more cholesteric liquid crystal polymer layers 1, 12, 13, 16 have a single-layer or multiple-layer support base material 11, 14, 15 at an appropriate position, or It may have an appropriate layer form in a form without a supporting substrate.
【００２９】前記において２層又は３層以上のコレステ
リック液晶ポリマー層の配置による円偏光分離層の形成
は、反射波長域の拡大等を目的とする。すなわち単層の
コレステリック液晶ポリマー層では通例、円偏光二色性
（選択反射）を示す波長域に限界があり、その限界は約
１００nmの波長域に及ぶ広い範囲の場合もあるが、その
波長範囲でも例えば液晶表示装置等に適用する場合に望
まれる可視光の全域には及ばないから、円偏光二色性
（反射波長域）の異なる２層以上のコレステリック液晶
ポリマー層を設けて可視光域の全域ないし可及的に全域
を反射波長域とする場合などの如く、円偏光二色性を示
す波長域を拡大させることを目的とする。In the above, the formation of the circularly polarized light separating layer by disposing two or three or more cholesteric liquid crystal polymer layers is aimed at expanding the reflection wavelength range and the like. That is, in a single cholesteric liquid crystal polymer layer, there is usually a limit to a wavelength range in which circular dichroism (selective reflection) is exhibited, and the limit may be a wide range up to a wavelength range of about 100 nm. However, since it does not cover the entire range of visible light desired when applied to a liquid crystal display device or the like, for example, two or more cholesteric liquid crystal polymer layers having different circular dichroism (reflection wavelength range) are provided to provide a visible light range. It is an object of the present invention to expand a wavelength region exhibiting circular dichroism, such as a case where the entire region or the entire region is a reflection wavelength region as much as possible.
【００３０】ちなみに円偏光二色性の中心波長が３００
〜９００nmのコレステリック液晶ポリマー層を同じ偏光
方向の円偏光を反射する組合せで、かつ円偏光二色性の
中心波長が異なる組合せで用いて、その２〜６種類を重
畳することで可視光域をカバーできる円偏光分離層を効
率的に形成することができる。本発明においては、可視
光の１５０nm以上の波長域にわたり円偏光二色性を示す
円偏光分離層であることが好ましい。Incidentally, the center wavelength of circular dichroism is 300.
Using a combination of cholesteric liquid crystal polymer layers of up to 900 nm to reflect circularly polarized light in the same polarization direction, and a combination of different central wavelengths of circular dichroism, the visible light range is obtained by superimposing two to six types. A circularly polarized light separating layer that can be covered can be efficiently formed. In the present invention, a circularly polarized light separating layer that exhibits circular dichroism over a wavelength region of visible light of 150 nm or more is preferable.
【００３１】円偏光分離層の薄型化等の点よりは、コレ
ステリック液晶ポリマー層の可及的に少ない配置数、就
中２層の配置数で目的の反射波長域を示すものが好まし
い。ちなみに可視光域では、反射光の中心波長が４００
〜５５０nm未満と５５０以上〜７００nmの範囲にある２
層のコレステリック液晶ポリマー層の配置でその全域な
いし可及的に全域を反射波長域とする円偏光分離層を得
ることができる。そのより好ましい組合せは、反射光の
中心波長が４５０〜５４０nm、就中４８０〜５２０nmの
範囲、特に約５００nmのものと、５６０〜６５０nm、就
中５８０〜６２０nmの範囲、特に約６００nmのものとの
２層である。From the standpoint of reducing the thickness of the circularly polarized light separating layer, it is preferable that the number of the cholesteric liquid crystal polymer layers is as small as possible, particularly the number of the two cholesteric liquid crystal polymer layers, shows the target reflection wavelength range. By the way, in the visible light range, the center wavelength of the reflected light is 400
Less than 550 nm and between 550 and 700 nm
By arranging the cholesteric liquid crystal polymer layers of the layers, a circularly polarized light separating layer having a whole or as much as possible the entire reflection wavelength region can be obtained. A more preferred combination is one having a center wavelength of the reflected light of 450 to 540 nm, particularly in the range of 480 to 520 nm, especially about 500 nm, and 560 to 650 nm, particularly in the range of 580 to 620 nm, especially about 600 nm. It has two layers.
【００３２】前記した２層のコレステリック液晶ポリマ
ー層の組合せは、視角変化、すなわち斜め透過光の出射
角度による色変化が小さい利点なども有している。なお
図２（ｅ）に例示した如き反射波長域の異なる３層以上
のコレステリック液晶ポリマー層１２，１３，１６を設
ける場合には、反射光の中心波長の長短に基づく波長順
序に配置することが、前記視角変化による出射光の色変
化を抑制する点などより好ましい。The combination of the two cholesteric liquid crystal polymer layers described above also has an advantage that a change in viewing angle, that is, a change in color due to an emission angle of obliquely transmitted light is small. When three or more cholesteric liquid crystal polymer layers 12, 13 and 16 having different reflection wavelength ranges as shown in FIG. 2E are provided, they may be arranged in a wavelength order based on the length of the center wavelength of the reflected light. It is more preferable that the color change of the emitted light due to the change in the viewing angle is suppressed.
【００３３】前記した２層以上のコレステリック液晶ポ
リマー層を配置する場合に、同じ偏光方向の円偏光を反
射するものの組合せとする点は、各層で反射される円偏
光の位相状態を揃えて各波長域で異なる偏光状態となる
ことを防止し、利用できる状態の偏光の増量を目的とす
る。When two or more cholesteric liquid crystal polymer layers are arranged as described above, the combination of those that reflect circularly polarized light having the same polarization direction is different in that the phase state of the circularly polarized light reflected by each layer is made uniform and the wavelength is changed. It is intended to prevent different polarization states in different regions, and to increase the amount of polarized light that can be used.
【００３４】前記したコレステリック液晶ポリマーにお
ける反射光の中心波長の相違は、クランジャン配向の螺
旋ピッチの相違に基づくが、本発明にては厚さ方向に螺
旋ピッチが変化する円偏光分離層や、螺旋ピッチ相違の
２層以上のコレステリック液晶ポリマー層が反射光の中
心波長に基づいて長短の順序通りに重畳して厚さ方向に
螺旋ピッチが変化する円偏光分離層などの適宜な形態の
円偏光分離層であってよい。The difference in the center wavelength of the reflected light in the cholesteric liquid crystal polymer is based on the difference in the helical pitch of the clan-jang orientation, but in the present invention, the circularly polarized light separating layer in which the helical pitch changes in the thickness direction, Circularly polarized light of an appropriate form such as a circularly polarized light separating layer in which two or more cholesteric liquid crystal polymer layers having different helical pitches are superimposed in the order of length and length based on the central wavelength of reflected light and the helical pitch changes in the thickness direction. It may be a separation layer.
【００３５】前記した螺旋ピッチが厚さ方向に変化する
構造も反射光の波長域の拡大などに有効である。その場
合、同じ螺旋ピッチのコレステリック液晶ポリマー層間
に、螺旋ピッチの異なるコレステリック液晶ポリマー層
が前記中心波長の長短の順序通りに１層又は２層以上介
在した形態のものの如く、同じ螺旋ピッチのコレステリ
ック液晶ポリマー層を２層以上含む層構造なども許容さ
れる。The above-described structure in which the helical pitch changes in the thickness direction is also effective for expanding the wavelength range of reflected light. In such a case, a cholesteric liquid crystal polymer layer having the same helical pitch is provided between the cholesteric liquid crystal polymer layers having the same helical pitch, and one or more cholesteric liquid crystal polymer layers having different helical pitches are interposed in the order of the central wavelength. A layer structure including two or more polymer layers is also acceptable.
【００３６】なお上記した螺旋ピッチが厚さ方向に変化
する円偏光分離層の製造は、例えば配向処理したコレス
テリック液晶ポリマー層の上に、上記したコレステリッ
ク液晶ポリマー層の形成操作に準じて、液晶ポリマーの
展開及びその加熱配向処理を行うことによりコレステリ
ック液晶ポリマー層を順次重畳する方式や、配向処理し
たコレステリック液晶ポリマー層同士の２枚又は３枚以
上の所定数を熱圧着により接着する操作などにより行う
ことができる。The production of the circularly polarized light separating layer in which the helical pitch changes in the thickness direction is performed, for example, by forming a liquid crystal polymer on an alignment-treated cholesteric liquid crystal polymer layer in accordance with the above-mentioned cholesteric liquid crystal polymer layer forming operation. The cholesteric liquid crystal polymer layer is sequentially superimposed by developing the cholesteric liquid crystal polymer layer by performing the development of the cholesteric liquid crystal polymer layer and the operation of bonding two or three or more predetermined numbers of the aligned cholesteric liquid crystal polymer layers by thermocompression bonding. be able to.
【００３７】支持基材との一体物からなる液晶ポリマー
の固化層の場合には、その固化層同士が密接するように
前記に準じて重畳処理することにより厚さ方向に螺旋ピ
ッチが変化する円偏光分離層、ひいては本発明による偏
光素子を得ることができる。なお熱圧着処理には、ロー
ルラミネータ等の適宜な加熱押圧手段を介してコレステ
リック液晶ポリマー層をガラス転移温度以上、等方相転
移温度未満に加熱して圧着処理する方式などの適宜な方
式を採ることができる。In the case of a solidified layer of a liquid crystal polymer formed integrally with the supporting base material, the solidified layers are superposed in accordance with the above so that the solidified layers are in close contact with each other, so that the helical pitch changes in the thickness direction. The polarization separation layer, and thus the polarization element according to the present invention, can be obtained. The thermocompression bonding process employs an appropriate system such as a system in which the cholesteric liquid crystal polymer layer is heated to a temperature equal to or higher than the glass transition temperature and lower than the isotropic phase transition temperature by an appropriate heating / pressing means such as a roll laminator to perform a compression bonding process. be able to.
【００３８】厚さ方向に螺旋ピッチが変化する円偏光分
離層は、連続した反射光の波長域を示すものであっても
よいし、不連続な反射光の波長域を示すものであっても
よい。色ムラ防止等の点より好ましい円偏光分離層は、
連続した反射光の波長域を示すものである。その製造
は、例えば上記した熱圧着操作等で形成したコレステリ
ック液晶ポリマー層の重畳体をガラス転移温度以上、等
方相転移温度未満に加熱して、その密着界面に上下の層
を形成するコレステリック液晶ポリマーが混合した配向
層を形成する方法などにより行うことができる。The circularly polarized light separating layer in which the helical pitch changes in the thickness direction may have a wavelength range of continuous reflected light or a wavelength range of discontinuous reflected light. Good. A circularly polarized light separating layer, which is preferable from the viewpoint of preventing color unevenness,
It shows the wavelength range of continuous reflected light. The cholesteric liquid crystal is manufactured by heating the cholesteric liquid crystal polymer layer formed by the above-mentioned thermocompression bonding operation or the like to a temperature equal to or higher than the glass transition temperature and lower than the isotropic phase transition temperature, thereby forming upper and lower layers at the adhesion interface. It can be performed by a method of forming an alignment layer in which a polymer is mixed, or the like.
【００３９】前記において、上下の層のコレステリック
液晶ポリマーが混合して形成されたコレステリック液晶
ポリマー層は、螺旋ピッチが上下の層とも異なって厚さ
方向に螺旋ピッチが多段階に変化した円偏光分離層を形
成し、通例その螺旋ピッチは上下の層を形成するコレス
テリック液晶ポリマー層の中間値をとって、上下の層と
共に連続した反射光の波長域を示す領域を形成する。In the above, the cholesteric liquid crystal polymer layer formed by mixing the cholesteric liquid crystal polymer of the upper and lower layers is different from the upper and lower layers in the circularly polarized light separation in which the helical pitch changes in multiple steps in the thickness direction. A layer is formed, and its helical pitch usually takes an intermediate value of the cholesteric liquid crystal polymer layers forming the upper and lower layers, and forms a region showing a continuous reflected light wavelength range together with the upper and lower layers.
【００４０】従って上下の層で反射光の波長域が重複し
ないコレステリック液晶ポリマー層の組合せ、すなわち
反射光の波長域に不連続による欠落域が存在する組合せ
で用いた場合に、上下の層の混合により形成されたコレ
ステリック液晶ポリマー層が前記欠落域を埋めて反射光
の波長域を連続化することができる。Therefore, when the combination of the cholesteric liquid crystal polymer layers in which the wavelength ranges of the reflected light do not overlap in the upper and lower layers, that is, the combination in which there is a discontinuity in the wavelength range of the reflected light, the mixing of the upper and lower layers is performed. The cholesteric liquid crystal polymer layer formed by the above method can fill the missing area to make the wavelength range of the reflected light continuous.
【００４１】よって例えば、反射波長域が５００nm以下
のものと６００nm以上のものの２種のコレステリック液
晶ポリマー層を用いて、反射波長域の不連続域である５
００〜６００nmの波長域の光についても反射する円偏光
分離層を得ることができ、これは少ないコレステリック
液晶ポリマー層の重畳で、広い帯域の反射波長域を示す
円偏光分離層を形成しうることを意味する。Thus, for example, a discontinuous reflection wavelength range is obtained by using two types of cholesteric liquid crystal polymer layers having a reflection wavelength range of 500 nm or less and a reflection wavelength range of 600 nm or more.
It is possible to obtain a circularly polarized light separating layer that reflects light in the wavelength range of 00 to 600 nm, which can form a circularly polarized light separating layer that exhibits a broad band reflection wavelength range by superimposing a small amount of cholesteric liquid crystal polymer layer. Means
【００４２】各コレステリック液晶ポリマー層の厚さ
は、配向の乱れや透過率低下の防止、反射光の波長範囲
（反射波長域）の広さなどの点より、０．５〜１００μ
m、就中１〜５０μm、特に１．５〜１０μmが好まし
い。また円偏光分離層の薄型化等の点よりコレステリッ
ク液晶ポリマー層の合計厚が１〜１００μm、就中２〜
５０μm、特に３〜２０μmであることが好ましい。さら
に支持基材を含めたコレステリック液晶ポリマー層の合
計厚は、２〜５００μm、就中１０〜３００μm、特に２
０〜２００μmであることが好ましい。The thickness of each cholesteric liquid crystal polymer layer is 0.5 to 100 μm in view of prevention of disorder in alignment and decrease in transmittance, and a wide wavelength range of reflected light (reflection wavelength range).
m, preferably 1 to 50 μm, particularly 1.5 to 10 μm. Further, the total thickness of the cholesteric liquid crystal polymer layer is 1 to 100 μm, and
It is preferably 50 μm, particularly preferably 3 to 20 μm. Further, the total thickness of the cholesteric liquid crystal polymer layer including the supporting base material is 2 to 500 μm, preferably 10 to 300 μm, particularly 2
It is preferably from 0 to 200 μm.
【００４３】なおコレステリック液晶ポリマーフィルム
又は液晶ポリマーの固化層と支持基材との一体物の２枚
以上を用いて円偏光分離層を形成するに際しては、図２
（ｅ）に例示の如く必要に応じ接着層２１，２２を介し
て密着処理することができる。また２層以上のコレステ
リック液晶ポリマー層の積層に際しては、各液晶ポリマ
ー層において１／４波長板側となる表面における液晶ポ
リマーが無配向状態にあることが輝度や視認性等の点よ
り好ましい。円偏光分離層の形成に際しては、コレステ
リック液晶ポリマー層に安定剤や可塑剤、あるいは金属
類などからなる種々の添加剤を必要に応じて配合するこ
とができる。When a circularly polarized light separating layer is formed by using two or more cholesteric liquid crystal polymer films or a solidified layer of a liquid crystal polymer and a support substrate, two or more sheets are formed as shown in FIG.
As shown in (e), the adhesion treatment can be performed via the adhesive layers 21 and 22 as necessary. When two or more cholesteric liquid crystal polymer layers are laminated, it is preferable that the liquid crystal polymer on the surface of each liquid crystal polymer layer on the quarter wavelength plate side is in a non-aligned state from the viewpoint of luminance, visibility, and the like. In forming the circularly polarized light separating layer, various additives such as stabilizers, plasticizers, and metals can be added to the cholesteric liquid crystal polymer layer as needed.
【００４４】本発明による偏光素子は、図例の如く円偏
光分離層１の上に、それを形成するコレステリック液晶
ポリマー層の平均屈折率ｎに対し屈折率がｎ±０．２の
接着層２を介して１／４波長板３を密着処理したもので
ある。輝度や色ムラ防止等の点より好ましい接着層の屈
折率は、ｎ±０．１５、就中ｎ±０．１０の範囲であ
る。なお前記した２層以上のコレステリック液晶ポリマ
ー層を接着するための接着層としても、前記屈折率を満
足することが輝度や色ムラ防止等の点より好ましい。The polarizing element according to the present invention comprises an adhesive layer 2 having a refractive index of n ± 0.2 with respect to an average refractive index n of a cholesteric liquid crystal polymer layer forming the circularly polarized light separating layer 1 as shown in the figure. 1/4 wavelength plate 3 is brought into close contact with the substrate. The preferable refractive index of the adhesive layer from the viewpoint of preventing luminance and color unevenness is in the range of n ± 0.15, especially n ± 0.10. In addition, it is preferable that the adhesive layer for bonding the two or more cholesteric liquid crystal polymer layers satisfies the above-mentioned refractive index from the viewpoint of preventing luminance and color unevenness.
【００４５】前記の１／４波長板は、直線偏光変換手段
として機能するものであり、円偏光分離層より出射した
円偏光が１／４波長板に入射して位相変化を受け、その
位相変化が１／４波長に相当する波長の光は直線偏光に
変換され、他の波長光は楕円偏光に変換される。変換さ
れた楕円偏光は、前記の直線偏光に変換された光の波長
に近いほど扁平な楕円偏光となる。かかる結果、偏光板
を透過しうる直線偏光成分を多く含む状態の光が１／４
波長板より出射されることとなる。The quarter-wave plate functions as a linearly polarized light converting means. Circularly polarized light emitted from the circularly polarized light separating layer enters the quarter-wave plate and undergoes a phase change. Is converted to linearly polarized light, and the other wavelength light is converted to elliptically polarized light. The converted elliptically polarized light becomes flat elliptically polarized light as it approaches the wavelength of the light converted into the linearly polarized light. As a result, light in a state containing a large amount of linearly polarized light component that can be transmitted through the polarizing plate is reduced to 1/4.
The light is emitted from the wave plate.
【００４６】直線偏光成分の多い状態に変換することに
より、偏光板を透過しやすい偏光度の高い光とすること
ができる。この偏光板は、例えば液晶表示装置の場合、
液晶セルに対する視野角の変化で発生する偏光特性の低
下を防止して表示品位を維持する光学層や、より高度な
偏光度を実現してよりよい表示品位を達成する光学層な
どとして機能するものである。By converting the light into a state having a large amount of linearly polarized light components, light having a high degree of polarization that can easily be transmitted through the polarizing plate can be obtained. This polarizing plate is, for example, in the case of a liquid crystal display device,
Functions as an optical layer that maintains the display quality by preventing the deterioration of the polarization characteristics caused by a change in the viewing angle with respect to the liquid crystal cell, and functions as an optical layer that achieves a higher degree of polarization and achieves a better display quality. It is.
【００４７】すなわち前記において、偏光板を用いず
に、円偏光分離層と１／４波長板よりの出射偏光をその
まま液晶セルに入射させて表示を達成することは可能で
あるが、偏光板を介することで前記した表示品位の向上
等をはかりうることから必要に応じて偏光板が用いられ
る。その場合に、偏光板に対する透過率の高いほど表示
の明るさの点より有利であり、その透過率は偏光板の偏
光軸（透過軸）と一致する偏光方向の直線偏光成分を多
く含むほど高くなるので、それを目的に１／４波長板を
介して円偏光分離層よりの出射円偏光を直線偏光に変換
するものである。That is, in the above, it is possible to achieve display by directly entering the polarized light emitted from the circularly polarized light separating layer and the quarter-wave plate into the liquid crystal cell without using the polarizing plate. Since the display quality can be improved by interposing the polarizing plate, a polarizing plate is used as necessary. In this case, the higher the transmittance of the polarizing plate, the more advantageous in terms of display brightness, and the higher the transmittance, the more the linear polarization component in the polarization direction coinciding with the polarization axis (transmission axis) of the polarizing plate. Therefore, for that purpose, the circularly polarized light emitted from the circularly polarized light separating layer is converted into linearly polarized light via a quarter wavelength plate.
【００４８】ちなみに、通例のヨウ素系偏光板に自然光
や円偏光を入射させた場合、その透過率は約４３％程度
であるが、直線偏光を偏光軸を一致させて入射させた場
合には８０％を超える透過率を得ることができ、従って
光の利用効率が大幅に向上して明るさに優れる液晶表示
などが可能となる。またかかる偏光板では、９９．９９
％に達する偏光度も達成できる。円偏光分離層の単独で
は、かかる高偏光度の達成は困難で、特に斜めからの入
射光に対する偏光度が低下しやすい。Incidentally, when natural light or circularly polarized light is incident on a usual iodine-based polarizing plate, the transmittance thereof is about 43%. However, when linearly polarized light is incident on the polarization axis coincident, it is 80%. %, So that the light use efficiency is greatly improved, and a liquid crystal display having excellent brightness can be realized. In such a polarizing plate, 99.99
% Can be achieved. It is difficult to achieve such a high degree of polarization by using the circularly polarized light separation layer alone, and particularly the degree of polarization with respect to obliquely incident light tends to decrease.
【００４９】１／４波長板としては、円偏光分離層より
出射した円偏光を、１／４波長の位相差に相当して直線
偏光を多く形成し、かつ他の波長の光を前記直線偏光と
可及的にパラレルな方向に長径方向を有して直線偏光に
近い扁平な楕円偏光に変換しうるものが好ましい。かか
る１／４波長板により、その出射光の直線偏光方向や楕
円偏光の長径方向が偏光板の透過軸と可及的に平行にな
るように配置して、偏光板を透過しうる直線偏光成分の
多い状態の光を得ることができ、液晶表示の明るさを向
上させることができる。As the quarter-wave plate, the circularly-polarized light emitted from the circularly-polarized light separating layer forms a large amount of linearly-polarized light corresponding to the phase difference of the quarter-wavelength, and converts the light of other wavelengths into the linearly-polarized light. It is preferable to use a material which has a major axis direction as parallel as possible and can be converted into flat elliptically polarized light close to linearly polarized light. With such a quarter-wave plate, the linear polarization direction of the emitted light and the major axis direction of the elliptically polarized light are arranged so as to be as parallel as possible to the transmission axis of the polarization plate, and a linear polarization component that can pass through the polarization plate. Light in many states can be obtained, and the brightness of the liquid crystal display can be improved.
【００５０】１／４波長板にて付与する位相差は、円偏
光分離層より出射される円偏光の波長域などに応じて適
宜に決定しうる。ちなみに可視光域では波長範囲や変換
効率等の点より、殆どの位相差板がその材質特性より正
の複屈折の波長分散を示すものであることも加味して、
その位相差が小さいもの、就中１００〜１８０nm、特に
１１０〜１５０nmの位相差を与えるものが好ましく用い
うる。The phase difference imparted by the quarter-wave plate can be appropriately determined according to the wavelength range of the circularly polarized light emitted from the circularly polarized light separating layer. By the way, in the visible light region, from the viewpoint of the wavelength range and conversion efficiency, etc., taking into account that most retardation plates show wavelength dispersion of positive birefringence from their material properties,
Those having a small phase difference, particularly those giving a phase difference of 100 to 180 nm, particularly 110 to 150 nm, can be preferably used.
【００５１】１／４波長板は、適宜な材質で形成でき、
透明で均一な位相差を与えるものが好ましく、一般には
位相差板が用いられる。また１／４波長板は、図２
（ａ）に例示の如く１層又は２層以上の位相差層３１，
３２の重畳層として形成することができる。１層からな
る位相差層の場合には、複屈折の波長分散が小さいもの
ほど波長毎の偏光状態の均一化をはかることができて好
ましい。一方、位相差層の重畳化は、波長域における波
長特性の改良に有効であり、その組合せは波長域などに
応じて適宜に決定してよい。The quarter-wave plate can be formed of an appropriate material.
Preferably, a transparent and uniform retardation is provided, and a retardation plate is generally used. The quarter-wave plate is shown in FIG.
As shown in (a), one or two or more retardation layers 31,
It can be formed as 32 overlapping layers. In the case of a single-layer retardation layer, the smaller the wavelength dispersion of birefringence, the better the polarization state can be made uniform for each wavelength, which is preferable. On the other hand, the superposition of the retardation layers is effective for improving the wavelength characteristics in the wavelength range, and the combination thereof may be appropriately determined according to the wavelength range.
【００５２】なお可視光域を対象に２層以上の位相差層
からなる１／４波長板とする場合、上記の如く１００〜
１８０nmの位相差を与える層を１層以上の奇数層として
含ませることが直線偏光成分の多い光を得る点より好ま
しい。１００〜１８０nmの位相差を与える層以外の層
は、通例２００nm以上の位相差を与える層、就中１／２
波長の位相差を与える層で形成することが波長特性の改
良等の点より好ましいが、これに限定するものではな
い。In the case where a quarter-wave plate comprising two or more retardation layers in the visible light region is used, as described above, 100 to 100
It is preferable to include a layer giving a phase difference of 180 nm as one or more odd-numbered layers from the viewpoint of obtaining light having a large amount of linearly polarized light components. Layers other than the layer giving a phase difference of 100 to 180 nm are usually layers giving a phase difference of 200 nm or more, especially 1/2.
It is preferable to form a layer having a wavelength phase difference from the viewpoint of improving wavelength characteristics, but the present invention is not limited to this.
【００５３】前記した位相差層は、上記の支持基材で例
示したプラスチックからなる延伸フィルムや液晶層、就
中、捩じれ配向の液晶層などとして得ることができる。
発光強度や発光色を広い視野角で均一に維持する点より
は、１／４波長板の面内における位相差の誤差が小さい
ほど好ましく、就中、その誤差が±１０nm以下であるこ
とが好ましい。The above-mentioned retardation layer can be obtained as a stretched film or a liquid crystal layer made of plastic exemplified as the above-mentioned support base material, especially, a liquid crystal layer having a twist orientation.
It is preferable that the error of the phase difference in the plane of the quarter-wave plate is smaller, more preferably the error is ± 10 nm or less, from the viewpoint of maintaining the emission intensity and the emission color uniformly at a wide viewing angle. .
【００５４】１／４波長板は、円偏光分離層の光出射側
に配置されるが、その配置位置は、視角変化による出射
光の色変化を抑制する点などより、円偏光分離層のコレ
ステリック液晶ポリマー層における反射光の中心波長の
大きい側（長波長側）であることが好ましい。１／４波
長板の厚さは、その位相差などに応じて適宜に決定しう
るが、一般には２〜３００μm、就中１０〜２００μm、
特に２０〜１５０μmの厚さとされる。The quarter-wave plate is disposed on the light exit side of the circularly polarized light separating layer. The position of the quarter wave plate is selected from the viewpoint of suppressing the color change of the emitted light due to the change of the viewing angle. It is preferably on the side where the center wavelength of the reflected light in the liquid crystal polymer layer is large (the long wavelength side). The thickness of the 波長 wavelength plate can be appropriately determined according to the phase difference and the like, but is generally 2 to 300 μm, preferably 10 to 200 μm,
In particular, the thickness is 20 to 150 μm.
【００５５】円偏光分離層と１／４波長板等を密着する
接着層としては、上記した屈折率を満足するものであれ
ばよく、その種類については特に限定はない。透明性に
優れるものが好ましい。一般には、例えばアクリル系ポ
リマーやシリコーン系ポリマー、エステル系ポリマーや
ウレタン系ポリマー、ポリエーテル系ポリマーや合成ゴ
ム系ポリマー、エチレン・酢酸ビニル共重合体系ポリマ
ーやエポキシ系樹脂等の適宜なポリマーを用いてなる接
着剤ないし粘着剤などが用いられる。The adhesive layer for adhering the circularly polarized light separating layer and the quarter-wave plate or the like may be any as long as it satisfies the above-mentioned refractive index, and the type thereof is not particularly limited. Those having excellent transparency are preferred. Generally, for example, using an appropriate polymer such as an acrylic polymer, a silicone polymer, an ester polymer, a urethane polymer, a polyether polymer, a synthetic rubber polymer, an ethylene / vinyl acetate copolymer polymer, or an epoxy resin. Adhesives or pressure-sensitive adhesives are used.
【００５６】本発明の偏光素子は、図３に例示した如く
それに拡散層４や偏光板５等の適宜な光学層の１種又は
２種以上を配置して、種々の形態に形成することができ
る。偏光板５は、上記した１／４波長板の機能より図例
の如く、１／４波長板３の上方に配置される。偏光板の
配置角は、その透過軸が１／４波長板を透過した直線偏
光の振動面に可及的に一致していることが輝度の向上等
の点より好ましい。なお偏光板を設けた形態の偏光素子
の場合には、液晶セルの光源側に設ける偏光板を省略す
ることができる。The polarizing element of the present invention can be formed in various forms by arranging one or more suitable optical layers such as the diffusion layer 4 and the polarizing plate 5 thereon as illustrated in FIG. it can. The polarizing plate 5 is disposed above the quarter-wave plate 3 as shown in the figure because of the function of the quarter-wave plate. Regarding the arrangement angle of the polarizing plate, it is preferable that the transmission axis coincides with the vibrating plane of the linearly polarized light transmitted through the quarter-wave plate as much as possible from the viewpoint of improving the luminance. In the case of a polarizing element provided with a polarizing plate, the polarizing plate provided on the light source side of the liquid crystal cell can be omitted.
【００５７】偏光板としては、適宜なものを用いうるが
一般には、偏光フィルムからなるものが用いられる。偏
光フィルムの例としては、ポリビニルアルコール系や部
分ホルマール化ポリビニルアルコール系、エチレン・酢
酸ビニル共重合体系部分ケン化物の如き親水性高分子の
フィルムにヨウ素及び／又は二色性染料を吸着させて延
伸したもの、ポリビニルアルコールの脱水処理物やポリ
塩化ビニルの脱塩酸処理物の如きポリエン配向フィルム
などがあげられる。As the polarizing plate, an appropriate polarizing plate can be used, but generally, a polarizing plate is used. Examples of the polarizing film include a film obtained by adsorbing iodine and / or a dichroic dye onto a hydrophilic polymer film such as a polyvinyl alcohol-based, partially formalized polyvinyl alcohol-based, or partially saponified ethylene / vinyl acetate copolymer. And polyene oriented films such as dehydration products of polyvinyl alcohol and dehydrochlorination products of polyvinyl chloride.
【００５８】偏光フィルムの厚さは通例５〜８０μmで
あるが、これに限定されない。偏光板は、偏光フィルム
の片面又は両面を透明保護層等で被覆したものなどであ
ってもよい。かかる透明保護層等は、偏光フィルムの補
強や耐熱性の向上、偏光フィルムを湿度等より保護する
ことなどの種々の目的を有するものであってよい。透明
保護層は、樹脂の塗布層や樹脂フィルムのラミネート層
などとして形成でき、拡散化や粗面化用等の微粒子を含
有していてもよい。The thickness of the polarizing film is usually 5 to 80 μm, but is not limited to this. The polarizing plate may be one obtained by coating one or both sides of a polarizing film with a transparent protective layer or the like. Such a transparent protective layer or the like may have various purposes such as reinforcing the polarizing film, improving heat resistance, and protecting the polarizing film from humidity and the like. The transparent protective layer can be formed as a resin coating layer or a resin film laminate layer, and may contain fine particles for diffusion or surface roughening.
【００５９】偏光素子に必要に応じて設ける拡散層は、
出射光を平準化して明暗ムラを抑制し、液晶セル等に適
用した場合に画素との干渉でモアレによるギラギラした
視認が生じることの防止などを目的とする。円偏光分離
層や１／４波長板より出射した光の偏光状態の維持性な
どの点より好ましく用いうる拡散層は、位相差が波長６
３３nmの垂直入射光、好ましくは入射角３０度以内の入
射光に基づいて３０nm以下、就中０〜２０nmのものであ
る。The diffusion layer provided on the polarizing element as required
An object of the present invention is to level out emitted light to suppress uneven brightness, and to prevent glare caused by moire due to interference with pixels when applied to a liquid crystal cell or the like. The diffusion layer, which can be preferably used from the viewpoint of maintaining the polarization state of the light emitted from the circularly polarized light separating layer and the quarter-wave plate, has a phase difference of 6
It is 30 nm or less, especially 0 to 20 nm, based on 33 nm vertically incident light, preferably incident light having an incident angle within 30 degrees.
【００６０】拡散層は、例えば粒子分散樹脂層の形成方
式、サンドブラストや化学エッチング等の表面凹凸化処
理による方式、機械的ストレスや溶剤処理等によるクレ
イズ発生方式、所定の拡散構造を設けた金型による転写
形成方式などの任意な方式で、円偏光分離層や１／４波
長板等への塗布層や拡散シートなどとして適宜に形成す
ることができる。拡散層は、円偏光分離層の片面や両
面、１／４波長板と偏光板の間やそれらの上面などの、
円偏光分離層や１／４波長板や偏光板等に隣接した適宜
な位置に１層又は２層以上を配置することができる。The diffusion layer may be formed, for example, by a method of forming a particle-dispersed resin layer, a method of surface roughening treatment such as sandblasting or chemical etching, a craze generation method by mechanical stress or solvent treatment, or a mold provided with a predetermined diffusion structure. In any method such as a transfer forming method, a circularly polarized light separating layer, a coating layer on a 波長 wavelength plate or the like, a diffusion sheet, or the like can be appropriately formed. The diffusion layer is formed on one side or both sides of the circularly polarized light separating layer, between the quarter-wave plate and the polarizing plate, or on the upper surface thereof.
One layer or two or more layers can be arranged at an appropriate position adjacent to a circularly polarized light separating layer, a quarter-wave plate, a polarizing plate, or the like.
【００６１】本発明による偏光素子は、偏光光源装置や
液晶表示装置の形成などに好ましく用いることができ
る。その例を図４に例示した。図は液晶表示装置７を示
しており、６が偏光光源装置である。この偏光光源装置
６によれば、側面からの入射光を上下面の一方より出射
する導光板６１の出射面側に配置した円偏光分離層１に
導光板より出射した光が入射し、左右一方の円偏光が透
過すると共に他方の円偏光が反射され、その反射光は、
戻り光として導光板に再入射する。導光板に再入射した
光は、下面の反射層６２等からなる反射機能部分で反射
されて再び円偏光分離板１に入射し、透過光と反射光
（再々入射光）に再度分離される。The polarizing element according to the present invention can be preferably used for forming a polarized light source device or a liquid crystal display device. An example is shown in FIG. The figure shows a liquid crystal display device 7, and 6 is a polarized light source device. According to the polarized light source device 6, the light emitted from the light guide plate enters the circularly polarized light separating layer 1 disposed on the emission surface side of the light guide plate 61 which emits the incident light from the side surface from one of the upper and lower surfaces. Is transmitted and the other circularly polarized light is reflected, and the reflected light is
The light returns to the light guide plate as return light. The light that has re-entered the light guide plate is reflected by the reflection function portion including the lower reflective layer 62 and the like, re-enters the circularly polarized light separating plate 1, and is again separated into transmitted light and reflected light (re-incident light).
【００６２】従って前記反射光としての再入射光は、円
偏光分離層を透過しうる所定の円偏光となるまで円偏光
分離層と導光板との間に閉じ込められて反射を繰返すこ
ととなるが、本発明においては再入射光の利用効率等の
点より、可及的に少ない繰返し数で、就中、初回の再入
射光が反射の繰返しなく出射するようにしたものが好ま
しい。Accordingly, the re-incident light as the reflected light is confined between the circularly polarized light separating layer and the light guide plate and is repeatedly reflected until the light becomes a predetermined circularly polarized light that can pass through the circularly polarized light separating layer. In the present invention, from the viewpoint of the efficiency of use of the re-incident light, it is preferable that the first re-incident light be emitted with as few repetitions as possible, especially without repetition of reflection.
【００６３】前記の導光板としては、側面からの入射光
を上下面の一方より出射する適宜なものを用いうる。か
かる導光板は、例えば透明又は半透明の樹脂板の光出射
面又はその裏面にドット状やストライプ状に拡散体を設
けたものや、樹脂板の裏面に凹凸構造、就中、微細プリ
ズムアレイからなる凹凸構造を付与したものなどとして
得ることができる。As the light guide plate, an appropriate one that emits incident light from the side surface from one of the upper and lower surfaces can be used. Such a light guide plate is, for example, a transparent or translucent resin plate having a light emitting surface or a diffuser provided in a dot shape or a stripe shape on the back surface thereof, or a concave and convex structure on the back surface of the resin plate, especially from a fine prism array. It can be obtained, for example, as having a concavo-convex structure.
【００６４】従って導光板は通例、一方が出射面となる
上下面、及び上下面間の少なくとも一側端面からなる入
射面を有する板状物からなる。図４の如く（冷，熱）陰
極管等の線状光源や発光ダイオード等の光源６３を側面
に配して光源光を入射させた場合に、板内を伝送される
光を拡散や反射、回折や干渉等により板の片面側に出射
するようにした、液晶表示装置で公知のサイドライト型
バックライトなどにおける導光板６１はその例である。Therefore, the light guide plate is generally formed of a plate-like object having upper and lower surfaces, one of which is an emission surface, and an entrance surface having at least one end surface between the upper and lower surfaces. As shown in FIG. 4, when a linear light source such as a (cold or hot) cathode tube or a light source 63 such as a light emitting diode is arranged on the side and light from the light source is incident, light transmitted through the plate is diffused or reflected. An example is a light guide plate 61 in a sidelight-type backlight or the like known in liquid crystal display devices, which emits light to one side of the plate by diffraction, interference, or the like.
【００６５】円偏光分離層を介して再入射した円偏光を
位相差の影響なくその円偏光状態を良好に維持したまま
下面に導き、また下面で反射した帰路光をその円偏光状
態を維持したまま出射させる点などより好ましく用いう
る導光板は、厚さ方向における複屈折による位相差が上
記した拡散層と同様に可及的に小さいものであり、就中
３０nm以下、特に０〜２０nmのものである。The circularly polarized light re-entered through the circularly polarized light separating layer was guided to the lower surface while maintaining its circularly polarized state satisfactorily without being affected by the phase difference, and the return light reflected by the lower surface was maintained in the circularly polarized state. A light guide plate that can be more preferably used, for example, a point where light is emitted as it is, has a phase difference due to birefringence in the thickness direction as small as possible as in the above-described diffusion layer, and is preferably 30 nm or less, particularly 0 to 20 nm It is.
【００６６】前記した一方の面側に光を出射する導光板
は、それ自体で円偏光分離層で反射された光を偏光変換
する機能を有しうるが、導光板の裏面に反射層６２を設
けることで反射ロスをほぼ完全に防止することができ
る。拡散反射層や鏡面反射層などの反射層は、円偏光分
離層で反射された光を偏光変換する機能に優れ、本発明
においては好ましい。The light guide plate that emits light to the one surface side can itself have a function of converting the light reflected by the circularly polarized light separation layer, but the reflection layer 62 is provided on the back surface of the light guide plate. By providing them, reflection loss can be almost completely prevented. A reflection layer such as a diffuse reflection layer or a specular reflection layer is excellent in the function of converting the light reflected by the circularly polarized light separation layer into a polarized light, and is preferable in the present invention.
【００６７】ちなみに凹凸面等で代表される拡散反射層
は、その拡散に基づいて偏光状態がランダムに混在し、
実質的に偏光状態を解消する。またアルミニウムや銀等
の蒸着層、それを設けた樹脂板、金属箔などからなる金
属面で代表される鏡面反射層は、円偏光が反射されると
その偏光状態が反転する。By the way, in the diffuse reflection layer represented by the uneven surface or the like, the polarization state is randomly mixed based on the diffusion.
Substantially eliminates the polarization state. When a circularly polarized light is reflected, the polarization state of a mirror reflection layer represented by a metal layer made of a vapor deposited layer of aluminum, silver, or the like, a resin plate provided with the layer, a metal foil, or the like is inverted.
【００６８】導光板の形成に際しては、光の出射方向を
制御するためのプリズムシート、均一な発光を得るため
の拡散板、漏れ光を戻すための反射手段、線状光源から
の出射光を導光板の側面に導くための光源ホルダ６４な
どの補助手段を必要に応じ所定位置に１層又は２層以上
配置して適宜な組合せ体とされる。When forming the light guide plate, a prism sheet for controlling the light emission direction, a diffusion plate for obtaining uniform light emission, a reflection means for returning leaked light, and a light guide for emitting light from the linear light source. Auxiliary means such as a light source holder 64 for guiding to the side surface of the light plate may be arranged in one or two or more layers at predetermined positions as necessary to form an appropriate combination.
【００６９】なお２層以上のプリズムシートを配置する
場合には、上下の層でプリズムアレイの配列方向が交差
するように配置することが、面全体での光出射方向の制
御による輝度の均一化などの点より好ましい。導光板の
光出射側に配置したプリズムシートや拡散板、あるいは
導光板に付与したドットなどは拡散効果等で反射光の位
相を変化させる偏光変換手段として機能しうる。When arranging two or more layers of prism sheets, it is preferable to arrange the prism arrays so that the arrangement directions of the prism arrays intersect each other in the upper and lower layers, so as to make the brightness uniform by controlling the light emission direction over the entire surface. It is more preferable than such points. A prism sheet or a diffusion plate disposed on the light exit side of the light guide plate, or a dot or the like provided on the light guide plate can function as a polarization conversion unit that changes the phase of reflected light due to a diffusion effect or the like.
【００７０】図４に例示の液晶表示装置７は、上記の偏
光光源装置６をバックライトシステムに用いたものであ
り、５が下側の偏光板、７１が液晶セル、７２が上側の
偏光板、７３が拡散板である。下側の偏光板５や拡散板
７３は、必要に応じて設けられる。本発明による偏光素
子を用いた偏光光源装置は、光の利用効率に優れて明る
い光を提供し、大面積化等も容易であり、明るくて視認
性に優れる液晶表示装置を形成する。The liquid crystal display device 7 illustrated in FIG. 4 uses the above-mentioned polarized light source device 6 in a backlight system, where 5 is a lower polarizing plate, 71 is a liquid crystal cell, and 72 is an upper polarizing plate. , 73 are diffusion plates. The lower polarizing plate 5 and the diffusion plate 73 are provided as needed. The polarized light source device using the polarizing element according to the present invention provides a bright liquid crystal display device which is excellent in light utilization efficiency, provides bright light, can be easily enlarged, and is bright and has excellent visibility.
【００７１】液晶表示装置は一般に、液晶シャッタとし
て機能する液晶セルとそれに付随の駆動装置、偏光板、
バックライト、及び必要に応じての補償用位相差板等の
構成部品の組立体などとして形成される。本発明におい
ては、上記した偏光素子による偏光光源装置を用いる点
を除いて特に限定はなく、従来に準じて形成でき、特に
直視型の液晶表示装置を好ましく形成しうる。In general, a liquid crystal display device includes a liquid crystal cell functioning as a liquid crystal shutter and a driving device, a polarizing plate,
It is formed as an assembly of components such as a backlight and, if necessary, a compensating phase plate. In the present invention, there is no particular limitation except that the above-mentioned polarized light source device using a polarizing element is used, and it can be formed according to a conventional method, and particularly a direct-view type liquid crystal display device can be preferably formed.
【００７２】従って用いる液晶セルについては特に限定
はなく、適宜なものを用いうる。就中、偏光状態の光を
液晶セルに入射させて表示を行うものに有利に用いら
れ、例えばツイストネマチック液晶やスーパーツイスト
ネマチック液晶を用いた液晶セル等に好ましく用いうる
が、非ツイスト系の液晶や二色性染料を液晶中に分散さ
せたゲストホスト系の液晶、あるいは強誘電性液晶を用
いた液晶セルなどにも用いうる。液晶の駆動方式につい
ても特に限定はない。Accordingly, the liquid crystal cell used is not particularly limited, and an appropriate one can be used. Above all, it is advantageously used for a display in which light in a polarization state is incident on a liquid crystal cell, and can be preferably used for a liquid crystal cell using, for example, a twisted nematic liquid crystal or a super twisted nematic liquid crystal. It can also be used for a guest-host type liquid crystal in which a dichroic dye is dispersed in a liquid crystal, or a liquid crystal cell using a ferroelectric liquid crystal. There is no particular limitation on the driving method of the liquid crystal.
【００７３】液晶表示装置の形成に際しては、例えば視
認側の偏光板の上に設ける拡散板やアンチグレア層、反
射防止膜や保護層や保護板、あるいは液晶セルと偏光板
の間に設ける補償用位相差板などの適宜な光学層を適宜
に配置することができる。In forming a liquid crystal display device, for example, a diffusion plate or an antiglare layer provided on a polarizing plate on the viewing side, an antireflection film, a protective layer or a protective plate, or a compensating retardation plate provided between a liquid crystal cell and a polarizing plate. An appropriate optical layer such as the above can be appropriately arranged.
【００７４】前記の補償用位相差板は、複屈折の波長依
存性などを補償して視認性の向上等をはかることを目的
とするものである。本発明においては、視認側又は／及
びバックライト側の偏光板と液晶セルの間等に必要に応
じて配置される。なお補償用位相差板としては、波長域
などに応じて適宜なものを用いることができ、１層又は
２層以上の重畳層として形成されていてよい。補償用位
相差板は、上記した１／４波長板で例示の延伸フィルム
などとして得ることができる。The purpose of the above-mentioned compensating phase difference plate is to improve the visibility by compensating the wavelength dependence of birefringence and the like. In the present invention, it is arranged as needed between the polarizing plate on the viewing side and / or the backlight side and the liquid crystal cell. As the retardation plate for compensation, an appropriate retardation plate can be used according to a wavelength range and the like, and it may be formed as one or two or more superposed layers. The compensating retardation plate can be obtained as a stretched film or the like exemplified by the above-described quarter-wave plate.
【００７５】本発明において、上記した偏光素子の偏光
板等や偏光光源装置や液晶表示装置を形成する部品は、
全体的又は部分的に積層一体化されて固着されていても
よいし、分離容易な状態に配置したものであってもよ
い。光学系のズレ防止等の点よりは固着されていること
が好ましい。その固着には、適宜な接着剤を用いうる
が、熱による光学歪の発生防止などの点よりは粘着剤が
好ましく用いうる。また接着対象の両部品に対し中間の
屈折率を示す接着剤が界面反射の抑制などの点より好ま
しい。In the present invention, the above-mentioned components such as the polarizing plate of the polarizing element, the polarized light source device, and the liquid crystal display device include:
It may be entirely or partially laminated and integrated and fixed, or may be arranged in an easily separable state. It is preferable to fix the optical system from the viewpoint of preventing the optical system from shifting. An appropriate adhesive may be used for the fixation, but an adhesive is preferably used from the viewpoint of preventing optical distortion due to heat. An adhesive having an intermediate refractive index for both parts to be bonded is preferable from the viewpoint of suppressing interfacial reflection and the like.
【００７６】なお液晶表示装置等の形成に際しては、垂
直性や平行光性に優れる出射光を供給し、円偏光分離層
を介した再入射光も散乱等によるロスや角度変化の少な
い状態で、かつ初期出射光との方向の一致性よく再出射
して、視認性の向上に有効な方向の出射光を効率よく供
給する偏光光源装置が好ましく用いうる。In the formation of a liquid crystal display device or the like, outgoing light having excellent perpendicularity and parallel light is supplied, and re-incident light passing through the circularly polarized light separating layer is reduced in loss and angle change due to scattering and the like. In addition, a polarized light source device that re-emits light with good coincidence with the direction of the initially emitted light and efficiently supplies emitted light in a direction effective for improving visibility can be preferably used.
【００７７】[0077]
実施例１ アクリル系サーモトロピックコレステリック液晶ポリマ
ーの２０重量％テトラヒドロフラン溶液を、厚さ８０μ
mの三酢酸セルロースフィルムからなる支持基材のポリ
ビニルアルコールラビング処理面（厚さ０．１μm）に
ワイヤバーにて塗工して乾燥後、１６０℃で５分間加熱
配向処理して冷却する方式で、厚さ３μmで左円偏光を
鏡面的に反射し、メソゲン比率の相違に基づいて選択反
射の波長域が４００〜４８０nm（青系）、４８０〜５８
０nm（緑系）又は５８０〜７００nm（赤系）の３種の液
晶ポリマー層を得た。その各液晶ポリマー層は、支持基
材側では液晶ポリマーがラビング方向に均一性よく配向
し、反対側の表面では液晶ポリマーがランダムな方向に
向いていて無配向の状態にあった。Example 1 A 20% by weight solution of an acrylic thermotropic cholesteric liquid crystal polymer in tetrahydrofuran was coated to a thickness of 80 μm.
m on a polyvinyl alcohol rubbed surface (thickness 0.1 μm) of a supporting substrate made of a cellulose triacetate film (thickness: 0.1 μm), followed by drying, heating, orientation treatment at 160 ° C. for 5 minutes, and cooling. Reflects left circularly polarized light specularly at a thickness of 3 μm, and has a selective reflection wavelength range of 400 to 480 nm (blue) and 480 to 58 based on the difference in mesogen ratio.
Three types of liquid crystal polymer layers having a thickness of 0 nm (green) or 580 to 700 nm (red) were obtained. In each of the liquid crystal polymer layers, the liquid crystal polymer was uniformly aligned in the rubbing direction on the supporting substrate side, and the liquid crystal polymer was oriented in a random direction on the opposite surface, and was in a non-aligned state.
【００７８】次に前記の青系、緑系及び赤系の液晶ポリ
マー層をその順序で、かつ液晶ポリマーの無配向側が１
／４波長板側となるように、しかも前記赤系の液晶ポリ
マー層の上にポリカーボネートからなる位相差１１５nm
の１／４波長板を有する順序で屈折率が１．５４のエポ
キシ系接着剤を介し密着処理して、円偏光分離層の上に
１／４波長板を有する偏光素子を得た。なお円偏光分離
層を形成する３種の液晶ポリマー層の平均屈折率は１．
６２であった。Next, the blue-based, green-based, and red-based liquid crystal polymer layers are formed in that order, and the non-aligned side of the liquid crystal polymer is 1 layer.
A retardation of 115 nm made of polycarbonate so as to be on the / 4 wavelength plate side and on the red liquid crystal polymer layer.
In the order in which the quarter-wave plate was provided, through an epoxy adhesive having a refractive index of 1.54 to obtain a polarizing element having a quarter-wave plate on the circularly polarized light separating layer. The average refractive index of the three types of liquid crystal polymer layers forming the circularly polarized light separating layer was 1.
62.
【００７９】比較例１ エポキシ系接着剤に代えて、屈折率が１．４１のフッ素
系アクリル接着剤を用いたほかは実施例１に準じて偏光
素子を得た。Comparative Example 1 A polarizing element was obtained in the same manner as in Example 1 except that a fluorine-based acrylic adhesive having a refractive index of 1.41 was used instead of the epoxy-based adhesive.
【００８０】比較例２ 各液晶ポリマー層の支持基材が１／４波長板側となるよ
うに処理したほかは実施例１に準じて偏光素子を得た。Comparative Example 2 A polarizing element was obtained in the same manner as in Example 1 except that each liquid crystal polymer layer was treated so that the supporting base material was on the 波長 wavelength plate side.
【００８１】評価試験 偏光度、透過率、色相 実施例、比較例で得た偏光素子における１／４波長板透
過光の偏光度、透過率及び色相（ａ，ｂ）を調べた。Evaluation Test Degree of Polarization, Transmittance, Hue The degree of polarization, transmittance, and hue (a, b) of the quarter-wave plate transmitted light in the polarizing elements obtained in the examples and comparative examples were examined.
【００８２】実施例、比較例で得た偏光素子をその円偏
光分離層側を介し面光源上に配置し、１／４波長板上の
正面方向の輝度と色相、及び左右斜め４０度方向の色相
を測定し、偏光素子を用いない場合の輝度を１００とし
たときの輝度割合、及び色相変化（△ｘｙ）を調べた。
なお色相変化は、偏光素子を用いない場合の色相を
ｘ0、ｙ0、前記実施例、比較例による偏光素子による場
合の色相をｘ1、ｙ1として次式より算出した。 △ｘｙ＝√｛（ｘ0−ｘ1）2＋（ｙ0−ｙ1）2｝The polarizing elements obtained in the examples and comparative examples were arranged on a surface light source via the circularly polarized light separating layer side, and the luminance and hue in the front direction on the 波長 wavelength plate and the light in the left and right oblique directions of 40 ° were observed. The hue was measured, and the luminance ratio and the hue change (Δxy) when the luminance when the polarizing element was not used were set to 100 were examined.
The hue change was calculated by the following equation, where x 0 and y 0 were the hues when no polarizing element was used, and x 1 and y 1 were the hues when using the polarizing elements according to the examples and the comparative examples. Δxy = {(x 0 −x 1 ) 2 + (y 0 −y 1 ) 2 }
【００８３】前記の結果を次表に示した。 The results are shown in the following table.
【図１】偏光素子例の断面図FIG. 1 is a cross-sectional view of a polarizing element example.
【図２】他の偏光素子例の断面図FIG. 2 is a cross-sectional view of another example of a polarizing element.
【図３】さらに他の偏光素子例の断面図FIG. 3 is a cross-sectional view of yet another example of a polarizing element.
【図４】偏光光源装置及び液晶表示装置例の断面図FIG. 4 is a cross-sectional view of a polarized light source device and an example of a liquid crystal display device.
１：円偏光分離層 １１，１４，１５：支持基材 １２，１３，１６：コレステリック液晶ポリマー層 ２，２１，２２：接着層 ３：１／４波長板 ３１，３２：位相差層 ４：拡散層 ５：偏光板 ６：偏光光源装置 ６１：導光板 ６２：反射層 ６３：光源 ７：液晶表示装置 1: Circularly polarized light separating layer 11, 14, 15: Support substrate 12, 13, 16: Cholesteric liquid crystal polymer layer 2, 21, 22: Adhesive layer 3: Quarter wave plate 31, 32: Retardation layer 4: Diffusion Layer 5: Polarizing plate 6: Polarized light source device 61: Light guide plate 62: Reflecting layer 63: Light source 7: Liquid crystal display device
フロントページの続き (72)発明者 三原 尚史 大阪府茨木市下穂積１丁目１番２号 日東 電工株式会社内Continuation of front page (72) Inventor Naofumi Mihara 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation
Claims (6)
ポリマー層からなる円偏光分離層の上に、前記コレステ
リック液晶ポリマー層の平均屈折率ｎに対し屈折率がｎ
±０．２の接着層を介して１／４波長板を有することを
特徴とする偏光素子。1. A cholesteric liquid crystal polymer layer having a refractive index of n with respect to an average refractive index n of the cholesteric liquid crystal polymer layer on a circularly polarized light separating layer comprising one or more cholesteric liquid crystal polymer layers.
A polarizing element having a quarter-wave plate via an adhesive layer of ± 0.2.
レステリック液晶ポリマー層の表面における液晶ポリマ
ーが無配向状態にある偏光素子。2. The polarizing element according to claim 1, wherein the liquid crystal polymer on the surface of the cholesteric liquid crystal polymer layer on the quarter wavelength plate side is in a non-aligned state.
が可視光の１５０nm以上の波長域にわたり円偏光二色性
を示すものである偏光素子。3. The polarizing element according to claim 1, wherein the circularly polarized light separating layer exhibits circular dichroism over a visible light wavelength range of 150 nm or more.
上方に偏光板を有する偏光素子。4. The polarizing element according to claim 1, further comprising a polarizing plate above the quarter-wave plate.
射する導光板の光出射側に請求項１〜４に記載の偏光素
子を有することを特徴とする偏光光源装置。5. A polarized light source device comprising the polarizing element according to claim 1 on a light emitting side of a light guide plate for emitting incident light from a side surface from one of upper and lower surfaces.
側に液晶セルを有することを特徴とする液晶表示装置。6. A liquid crystal display device having a liquid crystal cell on the light emission side of the polarized light source device according to claim 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30940797A JP3401743B2 (en) | 1997-10-22 | 1997-10-22 | Polarizing element, polarized light source device and liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30940797A JP3401743B2 (en) | 1997-10-22 | 1997-10-22 | Polarizing element, polarized light source device and liquid crystal display device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11125717A true JPH11125717A (en) | 1999-05-11 |
| JP3401743B2 JP3401743B2 (en) | 2003-04-28 |
Family
ID=17992646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30940797A Expired - Lifetime JP3401743B2 (en) | 1997-10-22 | 1997-10-22 | Polarizing element, polarized light source device and liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3401743B2 (en) |
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