JPH08271892A - Polarized light forming method, device therefor and liquid crystal display device - Google Patents
Polarized light forming method, device therefor and liquid crystal display deviceInfo
- Publication number
- JPH08271892A JPH08271892A JP7096306A JP9630695A JPH08271892A JP H08271892 A JPH08271892 A JP H08271892A JP 7096306 A JP7096306 A JP 7096306A JP 9630695 A JP9630695 A JP 9630695A JP H08271892 A JPH08271892 A JP H08271892A
- Authority
- JP
- Japan
- Prior art keywords
- light
- polarization
- polarized light
- liquid crystal
- reflection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133504—Diffusing, scattering, diffracting elements
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
- G02F1/133536—Reflective polarizers
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
- G02F1/133543—Cholesteric polarisers
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/13362—Illuminating devices providing polarized light, e.g. by converting a polarisation component into another one
Landscapes
- Liquid Crystal (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光の利用効率に優れる
偏光形成方法及びその装置、並びにそれを利用した明る
さに優れる液晶表示装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization forming method and a device therefor having excellent light utilization efficiency, and a liquid crystal display device using the same and having excellent brightness.
【０００２】[0002]
【従来の技術】従来、偏光形成方法としては、底面がプ
リズム状の導光板に側面より光を入射させて上面より出
射させ、その出射光を山形の干渉層からなる内部構造を
有する偏光分離手段を介し処理して偏光を得る方法が知
られていた（米国特許明細書第５３５９６９１号）。し
かしながら、視野角が狭く、色調の変化も大きくて直視
型の液晶表示装置等への適用は困難であり、光の反射ロ
スも多くて光の利用効率に乏しい問題点があった。2. Description of the Related Art Conventionally, as a method of forming polarized light, polarized light separating means having an internal structure in which light is incident on a light guide plate having a prism-shaped bottom surface from the side surface and emitted from the upper surface, and the emitted light is composed of a chevron interference layer. There has been known a method of obtaining polarized light by processing through (US Pat. No. 5,359,691). However, since the viewing angle is narrow and the change in color tone is large, it is difficult to apply to a direct-viewing type liquid crystal display device and the like, and there is a problem that light reflection loss is large and light utilization efficiency is poor.
【０００３】そのため、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等を用いた液晶セルを利用
する液晶表示装置では、表示に必要な偏光を専ら偏光板
を用いて形成している現状である。しかしながら、偏光
板では光量の約６０％程度が吸収されて熱等に変換さ
れ、光の利用効率としては３５〜４０％が通例で、理論
的にも５０％を超えることがないから光の利用効率に劣
る問題点があった。光の吸収を防止した偏光板の提案も
あるが、光の反射ロスが多くて光利用効率の実質的な向
上には至っていない（特開平１−１３３００３号公
報）。Therefore, in a liquid crystal display device using a liquid crystal cell using a twisted nematic liquid crystal, a super twisted nematic liquid crystal, or the like, the polarized light required for display is formed exclusively by using a polarizing plate. However, in the polarizing plate, about 60% of the light amount is absorbed and converted into heat, etc., and the light utilization efficiency is usually 35-40%, and theoretically it does not exceed 50%. There was a problem of poor efficiency. Although there is a proposal of a polarizing plate that prevents the absorption of light, it has not been able to substantially improve the light utilization efficiency due to a large amount of light reflection loss (JP-A-1-133003).
【０００４】従って、前記した光の利用効率に劣る偏光
形成方法や偏光板による方法では、それを用いて液晶表
示装置を形成した場合、バックライト等の光源系の明る
さを増す必要があり、装置の消費電力を増大させる問題
を誘発する。Therefore, in the above-described polarization forming method or polarizing plate method which is inferior in light utilization efficiency, when a liquid crystal display device is formed by using the method, it is necessary to increase the brightness of a light source system such as a backlight. It causes problems that increase the power consumption of the device.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、反射光の再
利用で反射ロスの発生を防止して光の利用効率に優れ、
明るさに優れる液晶表示装置を形成できる偏光形成方法
及びその装置の開発を課題とする。SUMMARY OF THE INVENTION The present invention prevents the occurrence of reflection loss by reusing reflected light and is excellent in light utilization efficiency.
An object of the present invention is to develop a polarization forming method and a device for forming a liquid crystal display device having excellent brightness.
【０００６】[0006]
【課題を解決するための手段】本発明は、偏光分離手段
を介して入射光における所定状態の偏光を透過させると
共に所定状態以外の偏光を反射させ、その反射光を反射
手段を介して再び前記偏光分離手段に入射させると共
に、その再入射前に偏光変換手段を介して前記反射光の
偏光状態を変化させることを特徴とする偏光形成方法、
及び板状発光層の片側に所定状態の偏光は透過し所定状
態以外の偏光は反射する偏光分離手段を有し、前記板状
発光層の他方側に反射手段を有すると共に、前記の偏光
分離手段と反射手段との間に偏光状態を変化させる偏光
変換手段を有することを特徴とする偏光形成装置を提供
するものである。According to the present invention, polarized light in a predetermined state of incident light is transmitted through polarized light separating means and polarized light other than the predetermined state is reflected, and the reflected light is again reflected through the reflecting means. A polarization forming method, characterized in that the polarization state of the reflected light is changed through the polarization conversion means before the light is incident on the polarization separation means again.
And a polarization separating means that transmits polarized light in a predetermined state and reflects polarized light other than the predetermined state on one side of the plate-like light emitting layer, and has a reflecting means on the other side of the plate-like light emitting layer, and the above-mentioned polarization separating means. The present invention provides a polarization forming device characterized in that it has a polarization conversion means for changing the polarization state between the reflection means and the reflection means.
【０００７】[0007]
【作用】上記の構成により、偏光分離手段で反射された
所定状態以外の偏光が反射手段との間に閉じ込められ、
偏光分離手段と反射手段との間で反射を繰り返す内に、
偏光変換手段を介し所定状態の偏光に変換されて偏光分
離手段より目的の偏光として、入射光における当初より
所定状態にある偏光と共に出射される。With the above structure, the polarized light other than the predetermined state reflected by the polarized light separating means is trapped between the reflecting means and
While repeating the reflection between the polarized light separating means and the reflecting means,
The polarized light is converted into polarized light in a predetermined state via the polarization converting means, and is emitted as the target polarized light from the polarization separating means together with the polarized light in the predetermined state from the beginning of the incident light.
【０００８】前記の結果、従来では反射光として利用さ
れず反射ロスとなっていた光も有効利用でき、光の利用
効率を向上させることができる。また偏光分離手段より
出射される光は、所定状態に偏光していることからパラ
レルな偏光板を用いることで８０％を超える透過量を実
現することが可能であり、偏光状態がより高度に揃って
いる場合には、偏光板を用いることなくそのまま液晶セ
ルに供給して明るさに優れる液晶表示装置を達成するこ
とも可能である。As a result, it is possible to effectively use the light which has not been used as the reflected light and causes the reflection loss in the related art, and it is possible to improve the light use efficiency. Further, since the light emitted from the polarization separating means is polarized in a predetermined state, it is possible to realize a transmission amount of more than 80% by using parallel polarizing plates, and the polarization state is more highly aligned. In this case, it is possible to supply a liquid crystal cell as it is without using a polarizing plate to achieve a liquid crystal display device having excellent brightness.
【０００９】[0009]
【実施例】本発明方法は、偏光分離手段を介して入射光
における所定状態の偏光を透過させると共に所定状態以
外の偏光を反射させ、その反射光を反射手段を介して再
び前記偏光分離手段に入射させると共に、その再入射前
に偏光変換手段を介して前記反射光の偏光状態を変化さ
せて所定状態の偏光を形成するものである。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, the polarized light in the predetermined state of the incident light is transmitted through the polarized light separating means and the polarized light other than the predetermined state is reflected, and the reflected light is returned to the polarized light separating means through the reflecting means. The polarized state of the reflected light is changed via the polarization conversion means before the incident light is made incident again to form polarized light in a predetermined state.
【００１０】前記偏光形成方法の実施は、例えば板状発
光層の片側に所定状態の偏光は透過し所定状態以外の偏
光は反射する偏光分離手段を有し、前記板状発光層の他
方側に反射手段を有すると共に、前記の偏光分離手段と
反射手段との間に偏光状態を変化させる偏光変換手段を
有する装置にて行うことができる。図１、図２に偏光形
成装置を例示した。１が偏光分離手段、２が板状発光
層、３が偏光変換手段、４が反射手段である。To carry out the above-described polarization forming method, for example, one side of the plate-like light emitting layer has polarization separating means for transmitting polarized light in a predetermined state and reflecting polarized light other than the predetermined state, and the other side of the plate-like light emitting layer is provided. This can be performed by an apparatus having a reflection means and a polarization conversion means for changing the polarization state between the polarization separation means and the reflection means. The polarization forming device is illustrated in FIGS. 1 and 2. Reference numeral 1 is a polarized light separating means, 2 is a plate-like light emitting layer, 3 is a polarization converting means, and 4 is a reflecting means.
【００１１】図例の装置によれば、板状発光層２に基づ
く光のうち所定状態の偏光は、板状発光層２の片側に配
置した偏光分離手段１を介して外部に透過する。一方、
所定状態以外の偏光は、偏光分離手段１で反射され、そ
の反射光は、板状発光層の他方側に配置した反射手段４
に入射し、その反射手段にて反射されて再び偏光分離手
段１に入射する。According to the apparatus shown in the figure, the polarized light in the predetermined state out of the light from the plate-shaped light emitting layer 2 is transmitted to the outside through the polarization splitting means 1 arranged on one side of the plate-shaped light emitting layer 2. on the other hand,
The polarized light other than the predetermined state is reflected by the polarized light separating means 1, and the reflected light is reflected by the reflecting means 4 arranged on the other side of the plate-like light emitting layer.
To the polarized light separating means 1 again.
【００１２】前記の偏光分離手段による反射光は、反射
手段にて反射されて再び偏光分離手段に入射するまでの
間に、その間に配置した偏光変換手段３を介して偏光状
態が変化させられ、一部又は全部の反射光が偏光分離手
段を透過しうる所定状態の偏光となる。従って前記の反
射光は、偏光分離手段を透過しうる所定状態の偏光とな
るまで偏光分離手段と反射手段との間に閉じ込められて
反射を繰り返す。The light reflected by the polarization splitting means has its polarization state changed by the polarization converting means 3 arranged between the reflection light and the polarization splitting means until it is incident on the polarization splitting means again. A part or all of the reflected light becomes polarized light in a predetermined state that can be transmitted through the polarized light separating means. Therefore, the reflected light is confined between the polarized light separating means and the reflecting means and repeatedly reflected until it becomes polarized light in a predetermined state which can be transmitted through the polarized light separating means.
【００１３】本発明の装置において、偏光分離手段、板
状発光層、偏光変換手段及び反射手段の各部品は、積層
一体化されていてもよいし、分離状態にあってもよい。
また偏光変換手段は、偏光分離手段と反射手段の間に１
層又は２層以上あればよく、反射手段が偏光変換手段を
兼ねるものとすることもできる。In the device of the present invention, the components of the polarization separating means, the plate-like light emitting layer, the polarization converting means and the reflecting means may be laminated and integrated, or may be in a separated state.
In addition, the polarization conversion means is provided between the polarization separation means and the reflection means.
The number of layers or two or more layers may be sufficient, and the reflection means may also serve as the polarization conversion means.
【００１４】板状発光層としては、適宜なものを用いう
る。好ましくは、光を吸収なく板状発光層の一方の面側
に効率的に出射するようにしたものが用いられる。
（冷，熱）陰極管等の線状光源や発光ダイオード等の光
源２１を導光板の側面に配し、その導光板に導光板内を
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はその例である。As the plate-like light emitting layer, an appropriate one can be used. It is preferable to use a material that efficiently emits light to one surface side of the plate-like light emitting layer without absorbing light.
A linear light source such as a (cold or heat) cathode tube or a light source 21 such as a light emitting diode is arranged on the side surface of the light guide plate, and the light transmitted through the light guide plate is diffused, reflected, diffracted or interfered with by the light guide plate. An example is a side-light type backlight, which is known in liquid crystal display devices, which emits light to one side of the plate.
【００１５】前記において内部の伝送光を片面側に出射
するようにした導光板は、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を付与
したものなどとして得ることができる。The above-mentioned light guide plate for emitting the transmitted light to the one side is, for example, a transparent or semi-transparent resin plate provided with a diffuser in a dot shape or a stripe shape on the light emitting surface or the back surface thereof. Alternatively, it can be obtained as a resin plate having an uneven structure on its back surface.
【００１６】板状発光層の形成に際しては、均一な発光
を得るための拡散板、ブライトネス・エンハンスド・フ
ィルム（スリーＭ社製）の如き光の出射方向を制御する
ためのプリズムシート、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、フレームなどの補助手段を必要に応じて所定位
置に配置して適宜な組合せ体とされる。In forming the plate-shaped light emitting layer, a diffusion sheet for obtaining uniform light emission, a prism sheet for controlling the light emitting direction such as a brightness enhanced film (manufactured by Three M), and a leak light are used. Reflective means for returning,
A suitable combination is formed by arranging auxiliary means such as a light source holder and a frame for guiding the light emitted from the linear light source to the side surface of the light guide plate at a predetermined position as necessary.
【００１７】板状発光層の光出射側に配置する偏光分離
手段としては、所定状態の偏光は透過し、所定状態以外
の偏光は反射する適宜なものが用いられる。ある方位の
振動方向の直線偏光は透過し、それに直交する方位の振
動方向の直線偏光は反射するもの、左右の円偏光を透過
・反射により分離するものなどはその例である。本発明
においては、完全な分離機能を有することは要しない
が、透過又は反射により分離された偏光中に含まれる他
の状態の偏光が少ないほど好ましい。As the polarized light separating means arranged on the light emitting side of the plate-like light emitting layer, an appropriate one that transmits polarized light in a predetermined state and reflects polarized light in a state other than the predetermined state is used. Examples thereof include one that transmits linearly polarized light in the vibration direction of a certain azimuth and reflects linearly polarized light in the vibration direction of the azimuth orthogonal to that, and one that separates left and right circularly polarized light by transmission and reflection. In the present invention, it is not necessary to have a complete separation function, but it is preferable that the polarized light separated by transmission or reflection contains less polarized light in other states.
【００１８】好ましく用いうる偏光分離手段としては、
コレステリック液晶相を有する層、就中コレステリック
相を呈する液晶ポリマーからなる層を有するシートや、
平滑な透明基板上に誘電体の多層膜を設けたものなどが
あげられる。ちなみに、コレステリック液晶相によれば
透過・反射により左右の円偏光に分離でき、前記誘電体
の多層膜によれば入射方向と平板の関係で決められるＰ
偏光成分（透過）とＳ偏光成分（反射）に分離できる。
視野角の広さの点よりは、コレステリック液晶相に基づ
くものが特に好ましい。As a polarized light separating means which can be preferably used,
A layer having a layer having a cholesteric liquid crystal phase, and particularly a sheet having a layer made of a liquid crystal polymer exhibiting a cholesteric phase,
An example thereof is one in which a dielectric multilayer film is provided on a smooth transparent substrate. By the way, according to the cholesteric liquid crystal phase, left and right circularly polarized light can be separated by transmission and reflection, and according to the multi-layered film of the dielectric, it is determined by the relationship between the incident direction and the flat plate.
It can be separated into a polarization component (transmission) and an S polarization component (reflection).
Those based on the cholesteric liquid crystal phase are particularly preferable from the viewpoint of wide viewing angle.
【００１９】偏光分離手段は、分離性能の均一化等の点
より平坦な層として形成されていることが好ましく、２
層以上の重畳層として形成されている場合でも各層は平
坦なものであることが好ましい。ちなみに、頂角が９０
度の断面山形のシートの間に多層干渉層を形成しそれを
別途のシートでカバーして平坦化したような板状物の如
く（1992 SID International Symposium Digest of Tec
hnical Papers／Volume XXIII／ISSN−0097−966X p42
7）、見掛け上は平坦でも内部に凹凸層が介在すると斜
め入射光に対する偏光分離機能、特に波長域による分離
性能が大きく変化して低下し、液晶表示装置への使用が
不向きなものとなる。また斜め入射光の透過状態も、凹
凸部に対する通過経路によって異なることとなり、均一
化を阻害する。The polarized light separating means is preferably formed as a flat layer from the viewpoint of uniformizing the separating performance.
Even when formed as a superposed layer of layers or more, each layer is preferably flat. By the way, the apex angle is 90
Like a plate-like object in which a multi-layer interference layer is formed between sheets having a chevron cross section and is covered with a separate sheet to be flattened (1992 SID International Symposium Digest of Tec
hnical Papers / Volume XXIII / ISSN-0097-966X p42
7) Even if the surface is apparently flat, the presence of an uneven layer inside makes the polarization separation function for obliquely incident light, especially the separation performance depending on the wavelength range, greatly deteriorate and deteriorates, making it unsuitable for use in liquid crystal display devices. Further, the transmission state of the obliquely incident light also differs depending on the passage route to the uneven portion, which hinders the uniformization.
【００２０】偏光分離手段は、前記の如く２層以上の重
畳層として形成することもできる。重畳化は、分離機能
の広波長域化に有利であり、その場合には所定状態以外
の偏光として反射する光の中心波長が異なる組合せで重
畳することが好ましい。ちなみにコレステリック液晶層
の場合、その液晶相に基づく選択反射の中心波長が３０
０〜９００nmのものを同じ偏光方向の円偏光を反射する
組合せで、かつ選択反射の中心波長が異なる、就中それ
ぞれ５０nm以上異なる組合せで用いて、その２〜６種類
を重畳することで広い波長域をカバーできる偏光分離手
段を効率的に形成することができる。コレステリック液
晶層の重畳には、製造効率や薄膜化などの点より液晶ポ
リマーの使用が特に有利である。The polarized light separating means can be formed as a superposed layer of two or more layers as described above. The superimposition is advantageous in widening the wavelength range of the separation function, and in that case, it is preferable to superimpose in a combination in which the central wavelengths of light reflected as polarized light other than the predetermined state are different. By the way, in the case of a cholesteric liquid crystal layer, the central wavelength of selective reflection based on the liquid crystal phase is 30.
Wide wavelength range by overlapping 2 to 6 types by using 0 to 900 nm in a combination that reflects circularly polarized light of the same polarization direction and different in the central wavelength of selective reflection, each of which is different by 50 nm or more. The polarized light separating means capable of covering the area can be efficiently formed. For the superposition of the cholesteric liquid crystal layer, the use of a liquid crystal polymer is particularly advantageous in terms of production efficiency and thinning.
【００２１】従って偏光分離手段としては、それが所定
状態以外の偏光として反射しうる光の波長域が板状発光
層に基づく出射光の波長域と可及的に一致したものが好
ましく用いうる。当該出射光に輝線スペクトル等の主波
長がある場合には、その１種又は２種以上の主波長に対
してコレステリック液晶相等に基づく反射光の波長を一
致させることが偏光分離の効率性等の点より次善策とな
り、必要重畳数の減少化等による偏光分離手段の薄層化
にも有利である。その場合、反射光の波長の一致の程度
は、板状発光層の１種又は２種以上の主波長光に対して
それぞれ２０nm以内の範囲とすることが好ましい。Therefore, as the polarized light separating means, one in which the wavelength range of the light which can be reflected as polarized light other than the predetermined state matches the wavelength range of the emitted light based on the plate-like light emitting layer as much as possible can be preferably used. When the emitted light has a dominant wavelength such as an emission line spectrum, it is possible to match the wavelength of the reflected light based on the cholesteric liquid crystal phase or the like with one or more dominant wavelengths of the polarized light, such as the efficiency of polarization separation. From the point, it is a second best measure, and it is also advantageous for thinning the polarization splitting means by reducing the required number of superpositions. In that case, it is preferable that the degree of coincidence of the wavelengths of the reflected light is within 20 nm for one or more main wavelengths of the plate-like light emitting layer.
【００２２】前記において、偏光分離手段をコレステリ
ック液晶の重畳層として形成する場合、同じ偏光方向の
円偏光を反射するものの組合せで用いることを指摘し
た。これは、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。In the above description, it was pointed out that when the polarized light separating means is formed as a superposed layer of cholesteric liquid crystal, it is used in combination with those which reflect circularly polarized light of the same polarization direction. This aims to increase the amount of polarized light in a usable state by preventing the circularly polarized light reflected by each layer from having different phase states in each wavelength range by aligning the phase states.
【００２３】なおコレステリック液晶としては、適宜な
ものを用いてよく、特に限定はない。位相差の大きいコ
レステリック液晶分子ほど選択反射の波長域が広くなっ
て好ましく用いうる。コレステリック液晶層の形態は、
例えば低分子量体をガラスや樹脂等の透明基材で挾持し
たセル形態、高分子による膜形態などの適宜な形態とす
ることができる。高分子を用いる方式が重さや自立性等
の点より好ましい。As the cholesteric liquid crystal, an appropriate one may be used without any particular limitation. A cholesteric liquid crystal molecule having a larger retardation has a wider wavelength range of selective reflection and can be preferably used. The form of the cholesteric liquid crystal layer is
For example, an appropriate form such as a cell form in which a low molecular weight substance is sandwiched by a transparent base material such as glass or resin, or a film form made of a polymer can be used. The method using a polymer is preferable in terms of weight and self-supporting property.
【００２４】コレステリック液晶層は、強度や操作性な
どに応じて１層又は２層以上の支持体で保持することが
できる。２層以上の支持体を用いる場合には、偏光の状
態変化を防止する点などより位相差が可及的に小さいも
のが好ましく用いうる。The cholesteric liquid crystal layer can be held by one or two or more supports depending on strength and operability. When a support having two or more layers is used, a support having a phase difference as small as possible is preferably used in order to prevent a change in the polarization state.
【００２５】板状発光層の偏光分離手段を設ける側とは
反対側に設ける反射手段については特に限定はなく、適
宜な反射層として形成することができる。反射が繰り返
された場合にもその反射光を効率的に偏光分離手段に入
射させて強度の低下を防止する点よりは、反射方向が大
きく変化しないものが好ましい。かかる点より好ましい
反射手段は、反射強度が最大となる方向が入射光の正反
射方向に対して３０度のコーン範囲内にあるものであ
る。The reflecting means provided on the side of the plate-like light emitting layer opposite to the side on which the polarized light separating means is provided is not particularly limited and can be formed as an appropriate reflecting layer. Even when the reflection is repeated, it is preferable that the reflection direction does not largely change from the viewpoint of efficiently causing the reflected light to enter the polarization splitting means and preventing the decrease in intensity. From this point of view, the preferred reflection means is one in which the direction of maximum reflection intensity is within the cone range of 30 degrees with respect to the regular reflection direction of incident light.
【００２６】偏光分離手段と反射手段の間に１層又は２
層以上が配置される偏光変換手段についても特に限定は
なく、偏光の状態を変えうる適宜なものを用いうる。そ
の例としては、偏光解消機能を有するもの、反射等に基
づいて偏光の位相状態を変化させうるものなどがあげら
れる。ちなみに偏光解消機能を有するものとしては、複
屈折性の微結晶粉末を含有するシート状物の如く光軸が
ランダムな微小複屈折体の集合体などを例示できる。ま
た偏光の位相を変化させうるものとしては、延伸繊維を
配列したシート状物などがあげられる。One layer or two layers are provided between the polarized light separating means and the reflecting means.
There is also no particular limitation on the polarization conversion means in which the layers or more are arranged, and an appropriate means that can change the polarization state can be used. Examples thereof include those having a depolarization function and those capable of changing the phase state of polarized light based on reflection and the like. By the way, as a material having a depolarizing function, an aggregate of minute birefringent bodies having random optical axes such as a sheet-like material containing birefringent microcrystalline powder can be exemplified. Examples of the material that can change the phase of polarized light include a sheet-shaped material in which stretched fibers are arranged.
【００２７】本発明においては、反射手段と偏光変換手
段とを一体化することもできるし、反射手段が偏光変換
手段を兼ねる同体物とすることもできる。その同体物と
しては、例えば拡散反射層や鏡面反射層などがあげられ
る。凹凸面等で代表される拡散反射層は、入射光の正反
射方向に最大の反射強度を示し、その拡散に基づいて偏
光状態がランダムに混在し偏光の解消状態を形成する。
仮に偏光が完全に解消しているとすると、次の偏光分離
手段への入射でその５０％が透過し、新たに板状発光層
に入射して所定状態の偏光として出射する光に付加さ
れ、光量が増大する。In the present invention, the reflection means and the polarization conversion means may be integrated, or the reflection means may be the same body which also serves as the polarization conversion means. Examples of the congener include a diffuse reflection layer and a specular reflection layer. The diffuse reflection layer represented by an uneven surface or the like exhibits maximum reflection intensity in the regular reflection direction of incident light, and polarization states are randomly mixed based on the diffusion to form a depolarized state.
If the polarized light is completely eliminated, 50% of the polarized light is transmitted by the next incident on the polarized light separating means, and is added to the light newly incident on the plate-like light emitting layer and emitted as the polarized light in a predetermined state, The amount of light increases.
【００２８】またアルミニウムや銀等の金属面で代表さ
れる鏡面反射層は、入射光の正反射方向に最大の反射強
度を示し、円偏光が反射されるとその偏光状態が反転す
る。従って、コレステリック液晶層からなる偏光分離手
段との組合せが特に好ましく、偏光状態の反転で理論的
には次の偏光分離手段への入射でその１００％が透過し
うる所定状態の偏光となる。Further, the specular reflection layer typified by a metal surface such as aluminum or silver exhibits the maximum reflection intensity in the specular reflection direction of incident light, and when circularly polarized light is reflected, its polarization state is inverted. Therefore, the combination with the polarization splitting means composed of the cholesteric liquid crystal layer is particularly preferable, and when the polarization state is inverted, theoretically, 100% of the polarized light can be transmitted when it enters the next polarization splitting means.
【００２９】拡散反射層や鏡面反射層は、板状物などと
してそれぞれ単独に用いることもできるし、それらが混
在した反射手段とすることもできる。また拡散反射層
は、導光板の裏面に設けて板状発光層が反射手段を兼
ね、従って偏光変換手段も兼ねるものとすることもでき
る。さらに板状発光層の裏面に拡散反射層や鏡面反射層
を付加して、板状発光層の裏面を含む全体が反射手段を
形成するものとすることもできる。The diffuse reflection layer and the specular reflection layer may be used individually as a plate-like material or may be a reflection means in which they are mixed. Further, the diffuse reflection layer may be provided on the back surface of the light guide plate so that the plate-like light emitting layer also serves as the reflection means, and thus also serves as the polarization conversion means. Further, a diffuse reflection layer or a specular reflection layer may be added to the back surface of the plate-like light emitting layer so that the entire surface including the back surface of the plate-like light emitting layer forms the reflecting means.
【００３０】上記のように本発明は、偏光分離手段によ
る反射光を偏光変換して出射光として利用し、これによ
り光の有効利用効率の増大をはかるものである。一方、
偏光分離手段からの出射光を光源として利用する点より
は、所定状態の偏光の比率が高いほど光利用効率の向上
に有利である。かかる観点より本発明においては、吸収
等による光損失等を考慮して、偏光分離手段を介して出
射する所定状態の偏光成分の強度が全出射光量の６５％
以上、就中７０％以上であることが好ましい。As described above, according to the present invention, the light reflected by the polarization separating means is polarized and used as outgoing light, thereby increasing the effective use efficiency of light. on the other hand,
The higher the ratio of polarized light in a predetermined state is, the more advantageous it is to improve the light use efficiency, rather than using the light emitted from the polarized light separating means as a light source. From this point of view, in the present invention, in consideration of light loss due to absorption and the like, the intensity of the polarized component in a predetermined state emitted through the polarization separation means is 65% of the total emitted light amount.
Above all, it is preferably 70% or more.
【００３１】本発明の装置は、光の利用効率に優れて明
るさに優れた所定状態の偏光を提供し、大面積化等も容
易であることより液晶表示装置等におけるバックライト
システムなどとして種々の装置に好ましく適用すること
ができる。図３に本発明装置をバックライトシステムに
用いた液晶表示装置を例示した。６は光拡散板、７は偏
光板、８は位相差板、９はカラー表示式の液晶セル、５
はバックライトシステムである。The device of the present invention provides polarized light in a predetermined state which is excellent in light utilization efficiency and brightness and can be easily enlarged to have a large area. Therefore, it can be used as a backlight system in liquid crystal display devices. It can be preferably applied to the above device. FIG. 3 illustrates a liquid crystal display device using the device of the present invention in a backlight system. 6 is a light diffusion plate, 7 is a polarizing plate, 8 is a retardation plate, 9 is a color display type liquid crystal cell, 5
Is a backlight system.
【００３２】液晶表示装置は一般に、偏光板、位相差
板、液晶セル、バックライト等の構成部品を適宜に組立
てて駆動回路を組込むことなどにより構成されるが、本
発明においては上記した偏光形成装置を光源に用いる点
を除いて特に限定はなく、従来に準じて形成することが
できる。すなわち、偏光状態の光を液晶セルに入射させ
る必要のある液晶表示装置であればよく、就中ツイスト
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、二色性染料を液晶中に分散させたゲスト
ホスト方式の液晶セルを用いた液晶表示装置などに好ま
しく用いうる。液晶の駆動方式については特に限定はな
く、いずれの駆動方式のものにも適用することができ
る。A liquid crystal display device is generally constituted by appropriately assembling components such as a polarizing plate, a retardation plate, a liquid crystal cell and a backlight and incorporating a drive circuit. In the present invention, the above-mentioned polarization formation is performed. There is no particular limitation except that the device is used as a light source, and it can be formed according to a conventional method. That is, any liquid crystal display device may be used as long as it is necessary to allow light in a polarized state to enter the liquid crystal cell. Among them, a liquid crystal cell using a twist nematic liquid crystal or a super twist nematic liquid crystal, a dichroic dye is dispersed in the liquid crystal. It can be preferably used for a liquid crystal display device using a guest-host type liquid crystal cell. The liquid crystal driving system is not particularly limited, and any driving system can be applied.
【００３３】なお液晶表示装置の形成に際し、偏光形成
装置による光の偏光状態が高度に均一化されている場合
には、それを液晶セルに直接入射させてセル入射側の偏
光板を省略することもできる。また位相差板は、必要に
応じて液晶セルの視認側や裏面側の適宜な位置に１層又
は２層以上を配置することができる。When the liquid crystal display device is formed, if the polarization state of the light by the polarization forming device is highly uniformed, it is directly incident on the liquid crystal cell and the polarizing plate on the cell incident side is omitted. You can also Further, the retardation plate may be provided with one layer or two or more layers at appropriate positions on the viewing side or the back side of the liquid crystal cell, if necessary.
【００３４】参考例１ アクリル系の主鎖を有するガラス転移温度が７５℃の側
鎖型コレステリック液晶ポリマーを、トリアセテートフ
ィルムのポリイミドラビング処理面にスピンコート方式
で成膜後、１３０℃で２分間アニールして鏡面状の選択
反射状態を呈する偏光分離板を得た。これは、４９０〜
５６０nmの波長範囲で選択反射領域を示し、この領域で
左円偏光を９０％以上反射する高い円偏光二色性を示し
た。Reference Example 1 A side chain type cholesteric liquid crystal polymer having an acrylic main chain and a glass transition temperature of 75 ° C. was formed on a polyimide rubbing-treated surface of a triacetate film by spin coating, and then annealed at 130 ° C. for 2 minutes. Thus, a polarization separation plate exhibiting a specular selective reflection state was obtained. This is 490
A selective reflection region was shown in the wavelength range of 560 nm, and high circular dichroism was observed in which 90% or more of left circularly polarized light was reflected.
【００３５】参考例２ アクリル系の主鎖を有するガラス転移温度が５７℃の側
鎖型コレステリック液晶ポリマーを、トリアセテートフ
ィルムのポリイミドラビング処理面にスピンコート方式
で成膜後、１００℃で２分間アニールして鏡面状の選択
反射状態を呈する偏光分離板を得た。これは、４３０〜
５１０nmの波長範囲で選択反射領域を示し、この領域で
左円偏光を９０％以上反射する高い円偏光二色性を示し
た。Reference Example 2 A side chain type cholesteric liquid crystal polymer having an acrylic main chain and a glass transition temperature of 57 ° C. was spin-coated on the polyimide rubbing-treated surface of a triacetate film, and then annealed at 100 ° C. for 2 minutes. Thus, a polarization separation plate exhibiting a specular selective reflection state was obtained. This is 430-
A selective reflection region was shown in a wavelength range of 510 nm, and high circular dichroism was observed in which 90% or more of left circularly polarized light was reflected.
【００３６】参考例３ アクリル系の主鎖を有するガラス転移温度が６４℃の側
鎖型コレステリック液晶ポリマーを、トリアセテートフ
ィルムのポリイミドラビング処理面にスピンコート方式
で成膜後、１２０℃で２分間アニールして鏡面状の選択
反射状態を呈する偏光分離板を得た。これは、５０５〜
６００nmの波長範囲で選択反射領域を示し、この領域で
左円偏光を９０％以上反射する高い円偏光二色性を示し
た。Reference Example 3 A side chain type cholesteric liquid crystal polymer having an acrylic main chain and a glass transition temperature of 64 ° C. was formed by spin coating on the polyimide rubbing treated surface of a triacetate film, and then annealed at 120 ° C. for 2 minutes. Thus, a polarization separation plate exhibiting a specular selective reflection state was obtained. This is 505
The selective reflection region was shown in the wavelength range of 600 nm, and high circular dichroism was observed in which 90% or more of the left circularly polarized light was reflected.
【００３７】参考例４ アクリル系の主鎖を有するガラス転移温度が７５℃の側
鎖型コレステリック液晶ポリマーを、トリアセテートフ
ィルムのポリイミドラビング処理面にスピンコート方式
で成膜後、１３５℃で３分間アニールして鏡面状の選択
反射状態を呈する偏光分離板を得た。これは、５９５〜
７１０nmの波長範囲で選択反射領域を示し、この領域で
左円偏光を９０％以上反射する高い円偏光二色性を示し
た。Reference Example 4 A side chain type cholesteric liquid crystal polymer having an acrylic main chain and a glass transition temperature of 75 ° C. was spin-coated on the polyimide rubbing-treated surface of a triacetate film, and then annealed at 135 ° C. for 3 minutes. Thus, a polarization separation plate exhibiting a specular selective reflection state was obtained. This is 595-
A selective reflection region was shown in the wavelength range of 710 nm, and in this region, high circular dichroism showing 90% or more of left circularly polarized light was shown.
【００３８】参考例５ 参考例２，３及び４で得た偏光分離板を積層して、選択
反射領域が４３０〜７１０nmで、前記同様の高い円偏光
二色性を示す重畳型の偏光分離板を得た。Reference Example 5 The polarization separation plates obtained in Reference Examples 2, 3 and 4 are laminated to form a superposition type polarization separation plate having a selective reflection region of 430 to 710 nm and exhibiting the same high circular dichroism as described above. Got
【００３９】参考例６ 底面幅が３００μmで頂角が９０度の二等辺三角形から
なる断面形を有する構造単位が連続したストライプ状の
凹凸面を片面に有するポリカーボネートシートの凹凸面
に、シートを１００℃に加熱しながら蒸着方式にてシー
ト平面の垂直方向に基づき厚さが１８６nmのフッ化マグ
ネシウム層と１１８nmの酸化ジルコニウム層を交互に１
１層重畳させ、その上に前記の凹凸面を有するポリカー
ボネートシートを凹凸面側を介して積層し、偏光分離板
を得た。この偏光分離板は、シート平面に垂直な方向の
入射光に対して、４２０〜６７０nmの波長範囲で選択反
射領域を示し、ストライプと平行な方向の偏光成分を９
０％以上反射する選択反射性を示した。Reference Example 6 A polycarbonate sheet having, on one side, a stripe-shaped uneven surface in which structural units each having a cross-sectional shape of an isosceles triangle having a bottom width of 300 μm and an apex angle of 90 degrees are continuous, is coated with 100 sheets of the uneven surface. While heating to ℃, by vapor deposition method, based on the vertical direction of the sheet plane, a magnesium fluoride layer having a thickness of 186 nm and a zirconium oxide layer having a thickness of 118 nm are alternately formed.
One layer was superposed, and the polycarbonate sheet having the irregular surface was laminated on the laminated sheet with the irregular surface side interposed therebetween to obtain a polarization separation plate. This polarization separation plate shows a selective reflection region in the wavelength range of 420 to 670 nm with respect to the incident light in the direction perpendicular to the sheet plane, and the polarization component in the direction parallel to the stripe is 9
It exhibited a selective reflectivity of reflecting 0% or more.
【００４０】実施例１ ポリメチルメタクリレートからなる厚さ５mmの導光板の
側面に直径４mmの冷陰極管を配置し、アルミニウム蒸着
フィルムにてその導光板の側面と冷陰極管を包囲した
後、導光板の片面を粗面化処理して光出射側とし、その
上に参考例３で得た偏光分離板を配置し、導光板の他面
に、ポリエステルフィルム上にチタン白を塗布した反射
板を配置して偏光形成装置を得た。前記の反射板は、そ
れに直線偏光のヘリウムネオンレーザを法線方向に対し
て１０度の角度で照射した場合、正反射方向に最大の反
射ピークを示し、反射光における元の直線偏光成分の強
度は、それと直交する方向の直線偏光成分の約１．３倍
を示し、偏光変換手段を兼ねるものであった。Example 1 A cold cathode tube having a diameter of 4 mm was arranged on the side surface of a light guide plate made of polymethylmethacrylate having a thickness of 5 mm, and the side surface of the light guide plate and the cold cathode tube were surrounded by an aluminum vapor-deposited film. One surface of the light plate was roughened to be the light emitting side, the polarization separation plate obtained in Reference Example 3 was placed on it, and the other surface of the light guide plate was a reflection plate in which titanium white was coated on a polyester film. It was arranged to obtain a polarization forming device. When the above-mentioned reflector plate is irradiated with a linearly polarized helium neon laser at an angle of 10 degrees with respect to the normal direction, it shows a maximum reflection peak in the regular reflection direction, and the intensity of the original linearly polarized light component in the reflected light. Shows about 1.3 times the linearly polarized light component in the direction orthogonal to that, and also serves as a polarization conversion means.
【００４１】実施例２ 反射板として、ポリエステルフィルム上に銀の蒸着膜を
設けた鏡面反射型のものを用いたほかは実施例１に準じ
て偏光形成装置を得た。Example 2 A polarization forming apparatus was obtained in the same manner as in Example 1 except that a specular reflection type in which a silver vapor deposition film was provided on a polyester film was used as the reflection plate.
【００４２】実施例３ 偏光分離板として、参考例５で得たものを用いたほかは
実施例１に準じて偏光形成装置を得た。Example 3 A polarization forming device was obtained in the same manner as in Example 1 except that the one obtained in Reference Example 5 was used as the polarization separation plate.
【００４３】実施例４ ポリメチルメタクリレートの平板からなる厚さ４mmの導
光板の片面にドットを設けて拡散反射面とし、その上に
実施例１で得た偏光解消型の偏光変換手段を兼ねる反射
板を配置し、その導光板の側面に直径３mmの冷陰極管を
配置してアルミニウム蒸着フィルムにてその導光板の側
面と冷陰極管を包囲した後、導光板の残る他面に拡散板
とプリズムシートを配置して光出射側とし、その上に参
考例５で得た偏光分離板を配置して偏光形成装置を得
た。Example 4 Dots were provided on one surface of a light guide plate having a thickness of 4 mm made of a flat plate of polymethylmethacrylate to form a diffuse reflection surface, and the reflection also serving as the depolarization-type polarization conversion means obtained in Example 1 was performed. A plate is arranged, a cold cathode tube having a diameter of 3 mm is arranged on the side surface of the light guide plate, the side surface of the light guide plate and the cold cathode tube are surrounded by an aluminum vapor deposition film, and then a diffusion plate is formed on the other surface of the light guide plate. A polarization sheet was obtained by arranging a prism sheet on the light emitting side, and disposing the polarization separation plate obtained in Reference Example 5 on the prism sheet.
【００４４】実施例５ 偏光分離板として、参考例６で得たものを用いてそのス
トライプが冷陰極管と平行になるように配置したほかは
実施例１に準じて偏光形成装置を得た。Example 5 A polarized light forming device was obtained in the same manner as in Example 1 except that the polarized light separating plate obtained in Reference Example 6 was used and the stripes were arranged in parallel with the cold cathode tubes.
【００４５】比較例１ 偏光分離板を配置しない以外は実施例１に準じて装置を
得た。Comparative Example 1 An apparatus was obtained in the same manner as in Example 1 except that the polarization separation plate was not arranged.
【００４６】比較例２ 反射板を配置しない以外は実施例１に準じて装置を得
た。Comparative Example 2 An apparatus was obtained in the same manner as in Example 1 except that the reflection plate was not arranged.
【００４７】比較例３ 偏光分離板を配置しない以外は実施例４に準じて装置を
得た。Comparative Example 3 An apparatus was obtained in the same manner as in Example 4 except that the polarization separation plate was not arranged.
【００４８】評価試験 実施例、比較例で得た装置につき、その冷陰極管と平行
な方向を左右方向、垂直な方向を上下方向として、かつ
冷陰極管配置側を上側として、主偏光成分に基づく正面
方向の輝度と、下４０度方向の輝度を輝度計（ミノルタ
カメラ社製）にて測定した。その結果を表１に示した。Evaluation Test For the devices obtained in the Examples and Comparative Examples, the direction parallel to the cold cathode tubes was the left-right direction, the vertical direction was the up-down direction, and the cold-cathode tube arrangement side was the upper side. The luminance in the front direction and the luminance in the lower 40 degree direction were measured with a luminance meter (Minolta Camera Co., Ltd.). The results are shown in Table 1.
【００４９】前記において主偏光成分は、実施例１〜４
においては位相差が１３０nmの位相差板をヨウ素系偏光
板（日東電工社製、ＮＰＦ Ｇ１２２９ＤＵ）と光学軸
が４５度又は１３５度で交差する角度で積層したものを
装置の前面に配置し、輝度の高い方を主偏光方向とし
た。また実施例５及び比較例では、前記に加えてヨウ素
系偏光板の単独物をその軸に基づいて回転させる方式で
輝度を調べ、それらの内で最大輝度を示した場合を主偏
光方向とした。In the above description, the main polarization component is the first to fourth embodiments.
In the above, a retardation plate having a retardation of 130 nm and an iodine-based polarizing plate (NPF G1229DU manufactured by Nitto Denko Corporation) are laminated at the angle where the optical axis intersects at 45 degrees or 135 degrees, and they are placed in front of the device to obtain the luminance. The higher one was taken as the main polarization direction. In addition, in Example 5 and Comparative Example, in addition to the above, in addition to the above, the iodine-based polarizing plate alone was rotated around its axis to examine the luminance, and the case where the maximum luminance was shown was taken as the main polarization direction. .
【００５０】[0050]
【表１】 [Table 1]
【００５１】前記の主偏光方向の輝度測定において実施
例１，２の場合、薄い緑色を呈していた。実施例５及び
比較例においては偏光板を単独使用したときに、いずれ
の場合も最大輝度を示し、その最大輝度は実施例５の場
合では偏光板の透過軸が上下方向のときに、比較例の場
合には左右方向のときにいずれの場合も現れた。In the above-mentioned luminance measurement in the main polarization direction, Examples 1 and 2 exhibited a light green color. In Example 5 and the comparative example, when the polarizing plate was used alone, the maximum luminance was shown in each case, and the maximum luminance is the comparative example when the transmission axis of the polarizing plate is in the vertical direction in the comparative example. In the case of, both cases appeared in the horizontal direction.
【００５２】前記の表１から、実施例１，２，３では、
比較例１，２と比較して、また実施例４では比較例３と
比較して主偏光方向の輝度が大きく向上していることが
わかる。これより、本発明における偏光分離手段及び反
射手段のいずれかが欠けても輝度の向上は達成されず、
輝度の向上にはそれらの両方が必要であることがわか
る。また実施例３の場合には主偏光方向の輝度が特に大
きく、これより偏光分離手段の対応できる波長域を広げ
ることで光の利用効率を向上させうることがわかる。From Table 1 above, in Examples 1, 2 and 3,
It can be seen that the luminance in the main polarization direction is significantly improved in comparison with Comparative Examples 1 and 2 and in Example 4 as compared with Comparative Example 3. From this, even if any one of the polarized light separating means and the reflecting means in the present invention is lacking, the improvement of the brightness is not achieved,
It can be seen that both of them are necessary to improve the brightness. Further, in the case of Example 3, it is found that the luminance in the main polarization direction is particularly large, and thus the utilization efficiency of light can be improved by widening the wavelength range that can be supported by the polarization separation means.
【００５３】さらに実施例３の場合には、実施例５との
比較より下４０度方向等の斜視方向における輝度にも優
れて視野角の変化による色調の変化も殆ど認めらず、ま
た正面方向での視認性もニュートラルな色調であり液晶
表示装置に適していることがわかる。なお実施例５の場
合、視野角の変化で色付きが認められ下４０度方向では
青色を呈して液晶表示装置には不向きであるが、正面方
向における輝度では実施例３の場合に匹敵する性能を示
し、正面用として有用な偏光形成装置であることがわか
る。Further, in the case of the third embodiment, compared with the fifth embodiment, the luminance in the oblique direction such as the lower 40 ° direction is excellent, the change in the color tone due to the change in the viewing angle is hardly recognized, and the front direction is observed. It can be seen that the visibility is also neutral and is suitable for liquid crystal display devices. In the case of Example 5, coloring was recognized due to a change in the viewing angle, and blue was shown in the lower 40 ° direction, which is unsuitable for a liquid crystal display device. However, with respect to the brightness in the front direction, a performance comparable to that of Example 3 was obtained. As shown, it can be seen that the polarizing device is useful for the front surface.
【００５４】実施例６ セルの上下面に偏光板を所定の角度で配置し、下面側の
偏光板の下面に偏光軸に対し４５度の光学軸で位相差が
１３５nmの位相差板を配置してなるノーマリーホワイト
の白黒表示式液晶セルを、実施例４で得た偏光形成装置
の上面に配置して液晶表示装置を形成し、非選択状態に
おける表示装置正面の輝度を調べた。Example 6 Polarizing plates are arranged on the upper and lower surfaces of the cell at a predetermined angle, and a retardation plate having an optical axis of 45 ° and a phase difference of 135 nm is arranged on the lower surface of the lower polarizing plate. The normally white black-and-white display type liquid crystal cell as described above was placed on the upper surface of the polarization forming device obtained in Example 4 to form a liquid crystal display device, and the brightness of the front face of the display device in the non-selected state was examined.
【００５５】比較例４ 比較例３で得た装置を用いて実施例６に準じ液晶表示装
置を形成して正面輝度を調べた。Comparative Example 4 Using the device obtained in Comparative Example 3, a liquid crystal display device was formed according to Example 6 and the front luminance was examined.
【００５６】比較例５ 位相差板を配置しない液晶セルを用いて比較例４に準じ
液晶表示装置を形成して正面輝度を調べた。Comparative Example 5 A liquid crystal display device was formed according to Comparative Example 4 using a liquid crystal cell in which no retardation plate was arranged, and the front luminance was examined.
【００５７】前記の結果を表２に示した。The above results are shown in Table 2.
【表２】 [Table 2]
【００５８】表２より、比較例４，５に比較して実施例
６の場合には輝度に優れる明るい表示の液晶表示装置が
実現されていることがわかる。また比較例４，５より、
位相差板の有無による輝度の変化は微差であることがわ
かる。From Table 2, it can be seen that, in comparison with Comparative Examples 4 and 5, in the case of Example 6, a bright display liquid crystal display device having excellent brightness was realized. Also, from Comparative Examples 4 and 5,
It can be seen that the change in luminance with or without the retardation plate is a slight difference.
【００５９】[0059]
【発明の効果】本発明によれば、偏光分離手段で反射さ
れる、従って従来法では利用されなかった光を目的の偏
光成分に変換して有効利用でき、光の利用効率に優れて
いる。また所定状態に偏光した光を多量に含む光が得ら
れて明るさに優れる液晶表示装置を得ることができる。According to the present invention, the light reflected by the polarization splitting means, which is not used in the conventional method, can be converted into the desired polarization component and can be effectively used, and the light utilization efficiency is excellent. Further, it is possible to obtain a light containing a large amount of light polarized in a predetermined state and obtain a liquid crystal display device having excellent brightness.
【図面の簡単な説明】[Brief description of drawings]
【図１】偏光形成装置例の断面図FIG. 1 is a cross-sectional view of an example of a polarization forming device.
【図２】他の偏光形成装置例の断面図FIG. 2 is a cross-sectional view of another example of a polarization forming device.
【図３】液晶表示装置例の断面図FIG. 3 is a sectional view of an example of a liquid crystal display device.
１：偏光分離手段 ２：板状発光層 ３：偏光変換手段 ４：反射手段 ５：バックライトシステム ７：偏光板 ９：液晶セル 1: Polarization separating means 2: Plate-shaped light emitting layer 3: Polarization converting means 4: Reflecting means 5: Backlight system 7: Polarizing plate 9: Liquid crystal cell
───────────────────────────────────────────────────── フロントページの続き (72)発明者 本村 弘則 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 (72)発明者 正田 位守 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 (72)発明者 中野 秀作 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 (72)発明者 吉見 裕之 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) Hironori Motomura 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Co., Ltd. (72) Inori Inori Mori 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Issue Nitto Denko Corporation (72) Inventor Shusaku Nakano 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Electric Works Ltd. (72) Hiroyuki Yoshimi 1-2 1-2 Shihohozumi, Ibaraki City, Osaka Nitto Electric Works Co., Ltd.
Claims (8)
定状態の偏光を透過させると共に所定状態以外の偏光を
反射させ、その反射光を反射手段を介して再び前記偏光
分離手段に入射させると共に、その再入射前に偏光変換
手段を介して前記反射光の偏光状態を変化させることを
特徴とする偏光形成方法。1. The polarized light in the incident light is transmitted through the polarized light separating means and the polarized light in a state other than the predetermined state is reflected, and the reflected light is incident on the polarized light separating means again through the reflecting means, A polarization forming method characterized in that the polarization state of the reflected light is changed via a polarization conversion means before the re-incident.
過し所定状態以外の偏光は反射する偏光分離手段を有
し、前記板状発光層の他方側に反射手段を有すると共
に、前記の偏光分離手段と反射手段との間に偏光状態を
変化させる偏光変換手段を有することを特徴とする偏光
形成装置。2. The plate-like light emitting layer has polarization separating means for transmitting polarized light in a predetermined state and reflecting polarized light in a state other than the predetermined state on one side, and has a reflecting means on the other side of the plate-like light emitting layer. A polarization forming device having a polarization conversion means for changing the polarization state between the polarization separation means and the reflection means.
て前記導光板の一方の面側に光を出射するようにしたも
のからなり、偏光分離手段がコレステリック液晶相を有
する層からなり、反射手段が入射光の正反射方向に対し
て３０度のコーン範囲内に最大の反射強度を示すもので
ある請求項２に記載の偏光形成装置。3. A layer in which a plate-shaped light emitting layer has a light source on a side surface of a light guide plate so as to emit light to one surface side of the light guide plate, and the polarization separation means has a cholesteric liquid crystal phase. 3. The polarization forming apparatus according to claim 2, wherein the reflecting means has a maximum reflection intensity within a cone range of 30 degrees with respect to the specular reflection direction of the incident light.
に基づく選択反射の中心波長が３００〜９００nmで同じ
偏光方向の円偏光を反射するコレステリック液晶ポリマ
ーの２〜６種類を選択反射の中心波長が異なる組合せで
重畳したものからなる請求項２又は３に記載の偏光形成
装置。4. The polarization separating means has a central wavelength of selective reflection based on a cholesteric liquid crystal phase of 300 to 900 nm and 2 to 6 kinds of cholesteric liquid crystal polymers which reflect circularly polarized light of the same polarization direction. The polarization forming device according to claim 2, wherein the polarization forming device is formed by combining and superimposing the combination.
光として反射する光の波長を板状発光層の主波長光に対
して２０nm以内の範囲で一致させたものである請求項２
〜４に記載の偏光形成装置。5. The polarization splitting means matches the wavelength of light reflected as polarized light other than the predetermined state with the main wavelength light of the plate-like light emitting layer within a range of 20 nm.
4. The polarization forming device described in 4 above.
射層又は拡散反射層であり、偏光分離手段を介して出射
する所定状態の偏光成分の強度が全出射光量の６５％以
上である請求項２〜５に記載の偏光形成装置。6. The reflection means is a specular reflection layer or a diffuse reflection layer that also serves as polarization conversion means, and the intensity of the polarized component in a predetermined state emitted through the polarization separation means is 65% or more of the total emitted light amount. The polarization forming device according to any one of 2 to 5.
源に用いたことを特徴とする液晶表示装置。7. A liquid crystal display device using the polarization forming device according to claim 2 as a light source.
ーパーツイストネマチック液晶又は二色性染料含有液晶
を用いたものである請求項７に記載の液晶表示装置。8. The liquid crystal display device according to claim 7, wherein the liquid crystal cell uses a twist nematic liquid crystal, a super twist nematic liquid crystal, or a dichroic dye-containing liquid crystal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7096306A JPH08271892A (en) | 1995-03-28 | 1995-03-28 | Polarized light forming method, device therefor and liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7096306A JPH08271892A (en) | 1995-03-28 | 1995-03-28 | Polarized light forming method, device therefor and liquid crystal display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08271892A true JPH08271892A (en) | 1996-10-18 |
Family
ID=14161352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7096306A Pending JPH08271892A (en) | 1995-03-28 | 1995-03-28 | Polarized light forming method, device therefor and liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08271892A (en) |
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| JPH10321025A (en) * | 1997-05-19 | 1998-12-04 | Nitto Denko Corp | Circularly polarized light-separating layer, optical element, polarized light source device, and liquid crystal display device |
| JPH1184370A (en) * | 1997-06-09 | 1999-03-26 | Seiko Epson Corp | Display element and electronic timepiece |
| WO1999024852A1 (en) * | 1997-10-16 | 1999-05-20 | Matsushita Electric Industrial Co., Ltd. | Hologram element polarization separating device, polarization illuminating device, and image display |
| JPH11160701A (en) * | 1997-11-27 | 1999-06-18 | Sanyo Electric Co Ltd | Back light device and liquid crystal display device |
| WO2000016154A1 (en) * | 1998-09-16 | 2000-03-23 | Teijin Limited | Application of light source including light guide for emanating linearly polarized light to liquid crystal display |
| EP0996025A1 (en) * | 1997-07-10 | 2000-04-26 | Citizen Watch Co., Ltd. | Liquid crystal display |
| KR20020009202A (en) * | 2000-07-25 | 2002-02-01 | 김순택 | Transflective type liquid crystal display |
| WO2002014740A1 (en) * | 2000-07-31 | 2002-02-21 | Matsushita Electric Industrial Co., Ltd. | Illuminator, image display, liquid crystal monitor, liquid crystal television, liquid crystal information terminal, and method for producing light guide plate |
| EP1424739A2 (en) | 2002-11-26 | 2004-06-02 | Nitto Denko Corporation | Organic elctroluminescence cell, planar light source and display device |
| US7722965B2 (en) | 2003-12-26 | 2010-05-25 | Nitto Denko Corporation | Electroluminescence device, planar light source and display using the same |
| JP2014509413A (en) * | 2011-03-09 | 2014-04-17 | ドルビー ラボラトリーズ ライセンシング コーポレイション | High contrast grayscale and color display |
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1995
- 1995-03-28 JP JP7096306A patent/JPH08271892A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10321025A (en) * | 1997-05-19 | 1998-12-04 | Nitto Denko Corp | Circularly polarized light-separating layer, optical element, polarized light source device, and liquid crystal display device |
| JPH1184370A (en) * | 1997-06-09 | 1999-03-26 | Seiko Epson Corp | Display element and electronic timepiece |
| EP0996025A1 (en) * | 1997-07-10 | 2000-04-26 | Citizen Watch Co., Ltd. | Liquid crystal display |
| EP0996025A4 (en) * | 1997-07-10 | 2004-03-10 | Citizen Watch Co Ltd | Liquid crystal display |
| WO1999024852A1 (en) * | 1997-10-16 | 1999-05-20 | Matsushita Electric Industrial Co., Ltd. | Hologram element polarization separating device, polarization illuminating device, and image display |
| JPH11160701A (en) * | 1997-11-27 | 1999-06-18 | Sanyo Electric Co Ltd | Back light device and liquid crystal display device |
| US6559909B1 (en) | 1998-09-16 | 2003-05-06 | Teijin Limited | Application of light source including light guide for emanating linearly polarized light to liquid crystal display with haze anisotropy |
| WO2000016154A1 (en) * | 1998-09-16 | 2000-03-23 | Teijin Limited | Application of light source including light guide for emanating linearly polarized light to liquid crystal display |
| KR20020009202A (en) * | 2000-07-25 | 2002-02-01 | 김순택 | Transflective type liquid crystal display |
| WO2002014740A1 (en) * | 2000-07-31 | 2002-02-21 | Matsushita Electric Industrial Co., Ltd. | Illuminator, image display, liquid crystal monitor, liquid crystal television, liquid crystal information terminal, and method for producing light guide plate |
| US7525531B2 (en) | 2000-07-31 | 2009-04-28 | Toshiba Matsushita Display Technology Co., Ltd. | Method for manufacturing lighting device, image display, liquid crystal monitor, liquid crystal television, liquid crystal information terminal, and light guide plate |
| EP1424739A2 (en) | 2002-11-26 | 2004-06-02 | Nitto Denko Corporation | Organic elctroluminescence cell, planar light source and display device |
| US7109651B2 (en) | 2002-11-26 | 2006-09-19 | Nitto Denko Corporation | Organic electroluminescence cell, planar light source and display device |
| US7722965B2 (en) | 2003-12-26 | 2010-05-25 | Nitto Denko Corporation | Electroluminescence device, planar light source and display using the same |
| JP2014509413A (en) * | 2011-03-09 | 2014-04-17 | ドルビー ラボラトリーズ ライセンシング コーポレイション | High contrast grayscale and color display |
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