JP3506914B2 - Liquid crystal display - Google Patents
Liquid crystal displayInfo
- Publication number
- JP3506914B2 JP3506914B2 JP18929698A JP18929698A JP3506914B2 JP 3506914 B2 JP3506914 B2 JP 3506914B2 JP 18929698 A JP18929698 A JP 18929698A JP 18929698 A JP18929698 A JP 18929698A JP 3506914 B2 JP3506914 B2 JP 3506914B2
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- JP
- Japan
- Prior art keywords
- polarized light
- light
- liquid crystal
- crystal display
- prism
- 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.)
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- Liquid Crystal (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、不定偏光である自
然光を用いた外光利用型の直視型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 direct-view type liquid crystal display device utilizing external light, which uses natural light of indefinite polarization.
【０００２】[0002]
【従来の技術】従来の直視型液晶ディスプレイは、液晶
パネル後面にバックライトを配置し、その光を利用して
映像を表示していた。ところが、バックライト光を利用
して映像を表示する場合、直射日光下などの明るいとこ
ろでは輝度が足りず、見えにくい映像となっていた。一
方、外光を光源として利用し、その反射光で映像を表示
するタイプの直視型液晶ディスプレイでは自発光をしな
いかわりに白昼の屋外などでも外光を利用して高輝度の
見やすい映像を表示することができる。その構成を図４
に示す。2. Description of the Related Art In a conventional direct-viewing type liquid crystal display, a backlight is arranged on the rear surface of a liquid crystal panel and the light is used to display an image. However, when an image is displayed using backlight light, the brightness is insufficient in a bright place such as in direct sunlight, which makes the image difficult to see. On the other hand, a direct-view LCD that uses external light as a light source and displays an image with the reflected light does not emit light by itself, but instead of using the external light, it can also use external light to display a high-luminance image that is easy to see. be able to. The structure is shown in FIG.
Shown in.
【０００３】一般的な外光利用型の液晶ディスプレイ
は、図４に概略するように外光入射側の上面から下面に
向けて偏光板７、ガラス８、液晶層９および反射板１０
によって構成されている。偏光板７からガラス８を経て
液晶層９に入射した光は、液晶によって変調された後に
反射板１０で反射され、再びガラス８から偏光板７を通
過して映像を為す。変調された光のうち、偏光板７を透
過する偏光方向を持つ光は白を表示し、偏光板７で吸収
される偏光方向を持つ光は黒となる。In a general liquid crystal display utilizing external light, as shown in FIG. 4, a polarizing plate 7, a glass 8, a liquid crystal layer 9 and a reflecting plate 10 are arranged from the upper surface to the lower surface on the external light incident side.
It is composed by. Light that has entered the liquid crystal layer 9 from the polarizing plate 7 through the glass 8 is modulated by the liquid crystal and then reflected by the reflecting plate 10, and passes through the glass 8 through the polarizing plate 7 again to form an image. Of the modulated light, light having a polarization direction that passes through the polarizing plate 7 displays white, and light having a polarization direction that is absorbed by the polarizing plate 7 becomes black.
【０００４】[0004]
【発明が解決しようとする課題】ところがこのとき偏光
板７に外から入射してくる外光は、一般的に特定の偏光
状態を持たない自然光であり、そのため入射偏光板７を
通過する際に約５０％が吸収され、透過した残りの５０
％の光を反射、変調して映像を作っているため、外光の
利用効率が悪いという問題点があった。However, the external light that is incident on the polarizing plate 7 from the outside at this time is generally natural light that does not have a specific polarization state. Therefore, when passing through the incident polarizing plate 7, About 50% is absorbed and the remaining 50 are transmitted
%, The light is reflected and modulated to create an image, so there is a problem that the utilization efficiency of outside light is poor.
【０００５】本発明は、前記の問題点を解消するために
なされたものであって、不定偏光である例えば自然光を
１方向の偏光方向を持つ直線偏光に変換するこで外光利
用型の直射型液晶ディスプレイの光利用効率を上げ、よ
り明るい画面を提供することを目的とする。The present invention has been made in order to solve the above problems, and converts indefinite polarized light, for example, natural light into linearly polarized light having one polarization direction, thereby directly irradiating external light. The purpose of the present invention is to improve the light utilization efficiency of a liquid crystal display and provide a brighter screen.
【０００６】[0006]
【課題を解決するための手段】本発明は、上記目的を達
成するため、次の構成を有する。第１の発明は、光の偏
光板と反射板の間に液晶層を備えた液晶表示パネルを有
する液晶表示装置であって、前記偏光板に対して傾斜す
るように偏光分離素子を挟み込んだプリズムを前記偏光
板の前面に設け、前記偏光分離素子は光の入射方向によ
って屈折率が異なる複屈折性を有することを特徴とする
液晶表示装置である。In order to achieve the above object, the present invention has the following constitution. A first invention is a liquid crystal display device having a liquid crystal display panel having a liquid crystal layer between a light polarization plate and a reflection plate, wherein a prism having a polarization separation element sandwiched so as to be inclined with respect to the polarization plate is provided. The liquid crystal display device is provided on the front surface of a polarizing plate, and the polarization separation element has a birefringence having a refractive index different depending on a light incident direction.
【０００７】 第２の発明は、画像を表示する液晶表示
パネルと、前記液晶表示パネルの出射側に設けられる一
方のプリズムと、入射光を、入射面に対して４５°傾い
た直線偏光と、前記直線偏光と直交した直線偏光とに、
一方を透過、他方を反射させて分離する偏光分離素子
と、前記一方のプリズムに前記偏光分離素子を挟んで設
ける他方のプリズムとを備える液晶表示装置であって、
前記他方のプリズムは、前記偏光分離素子により反射さ
れた偏光光を、プリズム表面で内部全反射を生じさせる
とともに、内部全反射された偏光光を、前記偏光分離素
子を透過した直線偏光光と長軸方向が一致した楕円偏光
光に偏光する機能を備え、前記分離された偏光光の偏光
方向を揃えるようにしたことを特徴とする液晶表示装置
である。According to a second aspect of the invention, a liquid crystal display panel for displaying an image, one prism provided on the exit side of the liquid crystal display panel, and linearly polarized light with incident light inclined at 45 ° with respect to the incident surface, In the linearly polarized light orthogonal to the linearly polarized light,
A liquid crystal display device comprising a polarization separating element that transmits one and reflects the other by separating, and the other prism provided by sandwiching the polarization separating element in the one prism,
The other prism causes the total internal reflection of the polarized light reflected by the polarization separation element on the prism surface, and the total internally reflected polarized light is longer than the linearly polarized light transmitted through the polarization separation element. A liquid crystal display device having a function of polarizing elliptically polarized light having the same axial direction and aligning the polarization directions of the separated polarized light.
【０００８】 第３の発明は、法線方向を異にする複数
の偏光分離素子を設けたことを特徴とする第１又は第２
の発明に記載の液晶表示装置である。A third aspect of the invention is the first or second aspect characterized in that a plurality of polarization separation elements having different normal directions are provided.
The liquid crystal display device according to the invention.
【０００９】 第４の発明は、偏光分離素子を挟み込ん
だプリズムは、偏光分離素子を挟み込んだプリズムを複
数組、平面状に組み合わせて構成することを特徴とする
第１乃至第３の発明のいずれかに記載の液晶表示装置で
ある。A fourth invention is characterized in that the prism having the polarization separating element sandwiched therein is formed by combining a plurality of pairs of the prisms sandwiching the polarization separating element in a planar shape.
A liquid crystal display device according to any one of the first to third inventions .
【００１０】 第１の発明によれば、プリズムに入射し
た光は、偏光分離素子により透過光と反射光に分離さ
れ、透過した直線偏光光はプリズムを通して偏光板に入
射し、一方、反射した直線偏光光もプリズムの表面にお
いて内部全反射されることで透過した直線偏光光と偏光
方向がほぼ揃えられて偏光板に入射することとなり、入
射光が偏光板にて吸収されるのを減じ、入射光の有効利
用を図ることができた。According to the first aspect of the invention, the light incident on the prism is separated into the transmitted light and the reflected light by the polarization separation element, and the transmitted linearly polarized light is incident on the polarizing plate through the prism, while the reflected linear light is reflected. The polarized light is also totally incident on the surface of the prism, and the polarization direction of the transmitted linearly polarized light is almost aligned with that of the polarized light so that the polarized light is incident on the polarizing plate. We were able to make effective use of light.
【００１１】 第２の発明によれば、２つのプリズムの
間に挟まれた偏光分離素子に入射した光は、偏光方向が
入射面に対して４５°傾いた直線偏光とそれと直交した
直線偏光とに一方を透過、一方を反射させて分離され
る。分離した直線偏光のうち透過した光は、プリズムを
通して液晶表示パネルに入射する一方、反射された光
は、一旦薄型プリズム表面で内部全反射されることで、
透過した直線偏光光とその長軸方向が一致した楕円偏光
光となって液晶表示パネルに入射することとなる。よっ
て、二つの分離された偏光光は、偏光方向を揃えた状態
で液晶表示パネルに入射することとなり、入射光を液晶
表示パネルの画像表示に有効に利用できる。According to the second invention, light incident on the polarization separation element sandwiched between two prisms, and linearly polarized light whose polarization direction is orthogonal to the linearly polarized light inclined 45 ° to the plane of incidence and that One is transmitted, and the other is reflected to be separated. The transmitted light of the separated linearly polarized light enters the liquid crystal display panel through the prism, while the reflected light is totally internally reflected on the surface of the thin prism,
The transmitted linearly polarized light and elliptically polarized light whose long axis direction coincide with each other enter the liquid crystal display panel. Therefore, the two separated polarized lights are incident on the liquid crystal display panel with their polarization directions aligned, and the incident light can be effectively used for image display on the liquid crystal display panel.
【００１２】 第３の発明によれば、複数の入射方向か
ら入射してきた外光を変換することができ、光の利用効
率をさらに上げることができ、第４の発明によれば、偏
光分離素子を挟み込んだプリズムの薄型、軽量化を図れ
るとともに、液晶表示パネルの大きさに限定されずに製
品化が可能となった。According to the third invention, it is possible to convert the external light that has entered from a plurality of incident directions, and it is possible to further improve the utilization efficiency of the light. According to the fourth invention, the polarization separation element It is possible to make the prism that encloses it thin and lightweight, and it is possible to commercialize it without being limited to the size of the liquid crystal display panel.
【００１３】[0013]
【発明の実施の形態】本願発明の実施の形態に係る液晶
表示装置を、図１を参照して説明する。図１は、それぞ
れ所定表面積を有した偏光板７、ガラス８、液晶層９お
よび反射板１０を積層した一般的な外光利用型の液晶表
示パネルの偏光板７の外側に後述する光学素子Ｂを張り
付けた液晶表示装置Ａの概略構成（電気配線等は説明を
省略する）を断面にて示したものである。DETAILED DESCRIPTION OF THE INVENTION A liquid crystal display device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows an optical element B which will be described later on the outside of the polarizing plate 7 of a general liquid crystal display panel utilizing external light in which a polarizing plate 7, a glass 8, a liquid crystal layer 9 and a reflecting plate 10 each having a predetermined surface area are laminated. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display device A to which is attached (an explanation of electric wiring and the like is omitted).
【００１４】光学素子Ｂは、同一傾斜面Ｂ１を有する第
１、第２のプリズム１、２のそれぞれの傾斜面Ｂ１を向
き合わせて、その両傾斜面Ｂ１の間に偏光分離素子３を
光学的なマッチングをとって挟み込み、上面Ｂ２及び下
面Ｂ３がフラットな板状体を形成している。そして光学
素子Ｂの下面Ｂ３が、偏光板７の外側（外光入射側）に
貼付けられている。In the optical element B, the respective inclined surfaces B1 of the first and second prisms 1 and 2 having the same inclined surface B1 are faced to each other, and the polarization separation element 3 is optically arranged between the both inclined surfaces B1. The upper surface B2 and the lower surface B3 form a flat plate-like body by sandwiching them with proper matching. Then, the lower surface B3 of the optical element B is attached to the outside of the polarizing plate 7 (external light incident side).
【００１５】偏光分離素子３は、入射自然光４を、入射
光進行方向と面の法線の為す入射面に対し、略４５度傾
いた偏光方向を持つ２つの直交した直線偏光光に、一方
は透過、他方は反射させて分離する機能を有している。
次に、上記機能を有する偏光分離素子３を詳細に説明す
る。例えば有機系ポリマーフィルムをある一方向で延伸
したとき、延伸方向の屈折率だけが変化し複屈折性（物
質の屈折率が方向によって異なる特性）を生じることか
ら、２種類のフィルムを重ねて１方向に延伸したとき、
２つのフィルム間において延伸方向の屈折率に差が生
じ、延伸方向と直交した方向の屈折率には差が生じない
ように２種類のフィルムを選択すると、このフィルムに
自然光（偏光していない光）をフィルム面に垂直に入射
させたとすると、フィルムの境界面において、延伸軸に
直交した方向の直線偏光は反射されないが、延伸軸方向
に偏光した直線偏光はそれぞれの境界面で反射されるこ
とになる。このような組み合わせのフィルムを（反射光
が干渉して打ち消されないよう厚さなどを選択して）複
数積み重ねれば、ある一方の直線偏光は透過するが、他
方は反射される光学素子である偏光分離素子３を作るこ
とができる。一般に用いられている光学多層膜による偏
光ビームスプリッターは、ｐ，ｓ偏光の斜め入射による
反射率特性の違いを用いているため、入射面（ミラー面
法線と入射光進行方向の為す面）に対して垂直なｓ偏光
と平行なｐ偏光にしか分離できない。これに対してこの
複屈折性多層構造フィルムでは、その延伸軸方向を入射
面に対してどのようにとろうと任意であるので、入射面
に対して任意の角度を持った直交した直線偏光に分離す
ることができる。The polarization separating element 3 converts the incident natural light 4 into two orthogonal linearly polarized lights having a polarization direction inclined by about 45 degrees with respect to the incident surface formed by the incident light traveling direction and the normal to the surface, one of which is one. It has a function of transmitting and the other has a function of reflecting and separating.
Next, the polarization separation element 3 having the above function will be described in detail. For example, when an organic polymer film is stretched in one direction, only the refractive index in the stretching direction changes and birefringence (a characteristic in which the refractive index of a substance varies depending on the direction) is generated. When stretched in the direction
When two kinds of films are selected so that there is a difference in the refractive index in the stretching direction between the two films and there is no difference in the refractive index in the direction orthogonal to the stretching direction, natural light (unpolarized light) ), The linearly polarized light in the direction orthogonal to the stretching axis is not reflected at the boundary surface of the film, but the linearly polarized light polarized in the stretching axis direction is reflected at each boundary surface. become. By stacking multiple films of such a combination (by selecting the thickness etc. so that reflected light does not interfere and cancel the reflected light), one linearly polarized light is transmitted, but the other is an optical element that is reflected. The polarization separation element 3 can be made. Since a polarization beam splitter using an optical multilayer film that is generally used uses the difference in reflectance characteristics due to the oblique incidence of p and s polarized light, it can be used on the incident surface (the surface defined by the mirror surface normal and the incident light traveling direction). On the other hand, it can only be separated into vertical s-polarized light and parallel p-polarized light. On the other hand, in this birefringent multilayer structure film, the stretching axis direction is arbitrary regardless of the direction of incidence, so it is separated into orthogonal linearly polarized light with an arbitrary angle with respect to the plane of incidence. can do.
【００１６】以上説明した構成の液晶表示装置Ａによれ
ば、第１のプリズム１を経て偏光分離素子３に入射した
入射自然光４は、透過偏光光５と反射偏光光６に分離さ
れ、２つに分離された直線偏光のうち反射偏光光６は、
第１のプリズム１の表面で全反射され、その長軸方向が
偏光分離素子３を透過した直線偏光の偏光方向とほぼ一
致した楕円偏光光となって、二つの分離された偏光光の
偏光方向がほぼ揃えられることとなるので、両偏光光が
偏向板７を透過し、入射自然光を有効に利用できる。According to the liquid crystal display device A having the above-described structure, the incident natural light 4 that has entered the polarization separation element 3 through the first prism 1 is separated into the transmitted polarized light 5 and the reflected polarized light 6, and is divided into two. The reflected polarized light 6 of the linearly polarized light separated into
Elliptical polarized light that is totally reflected on the surface of the first prism 1 and has a major axis direction that is substantially the same as the polarization direction of the linearly polarized light that has passed through the polarization splitting element 3 becomes the polarization directions of the two separated polarized lights. Are substantially aligned, both polarized lights pass through the deflecting plate 7, and incident natural light can be effectively used.
【００１７】すなわち、偏光分離素子３に入射した自然
光は、偏光の分離が行われる際に、直線偏光の偏光方向
を入射光進行方向と偏光分離を行なう面の法線の為す入
射面に対して、略４５度傾いた偏光方向の互いに直交し
た偏光光に分離される。尚、この機能は、光学薄膜を用
いた偏光ビームスプリッターなどでは実現できないが、
複屈折性を用いた偏光分離光学素子などにより実現可能
である。That is, the natural light incident on the polarization beam splitting element 3 is incident on the plane of incidence where the polarization direction of linearly polarized light is the normal to the incident light traveling direction and the plane for polarization separation when the polarization is separated. , And are separated into polarized lights that are orthogonal to each other and have a polarization direction inclined by about 45 degrees. It should be noted that this function cannot be realized with a polarizing beam splitter using an optical thin film,
It can be realized by a polarization splitting optical element using birefringence.
【００１８】分離された直線偏光光の一方は、その進行
方向と反射面の法線が為す入射面に対して略４５度傾い
た方向に偏光しており、反射面Ｂ２で全反射されること
でその長軸方向がもう一方の直線偏光の偏光方向とほぼ
平行な楕円偏光光に変換される。屈折率ｎ1の媒質から
ｎ2（ｎ1＞ｎ2）の媒質に入射角度θ1で入射すると、θ
1が下記の式（１）の条件を満たしたとき、One of the separated linearly polarized lights is polarized in a direction inclined by approximately 45 degrees with respect to the incident surface formed by the traveling direction and the normal line of the reflecting surface, and is totally reflected by the reflecting surface B2. Is converted into elliptically polarized light whose major axis direction is substantially parallel to the polarization direction of the other linearly polarized light. When a medium having a refractive index n 1 enters a medium having a refractive index n 2 (n 1 > n 2 ) at an incident angle θ 1 ,
When 1 satisfies the condition of the following formula (1),
【００１９】[0019]
【数１】 [Equation 1]
【００２０】全反射をおこす。このとき、ｐ偏光、ｓ偏
光間には下記の式（２）により求められる位相差δ＝δ
ｐ−δｓが生じる。Total reflection occurs. At this time, the phase difference between the p-polarized light and the s-polarized light is calculated by the following equation (2) δ = δ
p-δs occurs.
【００２１】[0021]
【数２】 [Equation 2]
【００２２】これにより反射後の偏光は楕円偏光になる
が、δが９０°を超えないよう媒質や入射角度を選択す
れば、楕円の長軸方向はもう一方の直線偏光の偏光方向
と平行になる。例えばその進行方向と反射面の法線が為
す入射面に対して４５度傾いて偏光している直線偏光光
が、屈折率ｎ1＝１．５２のガラスの内部から外部の空
気層（ｎ2＝１．０）に向かって入射角度４５°で入射
したとき、臨界角が４１．１°だから、この光は全反射
する。このとき反射光においてｐ偏光成分、ｓ偏光成分
の間にδ＝４０．３°の位相差が生じるので、楕円率
０．３７の楕円偏光となるが、位相差は９０°に満たな
いため、その長軸方向がもう一方の直線偏光の偏光方向
と平行な楕円偏光光に変換されることになる。As a result, the polarized light after reflection becomes elliptically polarized light, but if the medium and incident angle are selected so that δ does not exceed 90 °, the major axis direction of the ellipse becomes parallel to the polarization direction of the other linearly polarized light. Become. For example, linearly polarized light that is polarized at an angle of 45 degrees with respect to the incident surface formed by the traveling direction and the normal line of the reflecting surface is converted from the inside of the glass having the refractive index n 1 = 1.52 to the outside air layer (n 2 = 1.0), the light is totally reflected because the critical angle is 41.1 °. At this time, since a phase difference of δ = 40.3 ° occurs between the p-polarized component and the s-polarized component in the reflected light, the elliptically polarized light has an ellipticity of 0.37, but since the phase difference is less than 90 °, The major axis direction is converted into elliptically polarized light parallel to the polarization direction of the other linearly polarized light.
【００２３】従って、上記手段を用いて分離された入射
面に対して４５度傾いた２つの直交する偏光光のうち、
一方を全反射させてその長軸方向がもう一方の直線偏光
の偏光方向と平行な楕円偏光光に変換したことで、２つ
の分離した偏光光の偏光方向をほぼ揃えることができる
のである。（自然光をある１つの偏光方向に変換する詳
細な原理は後述する。）Therefore, of the two orthogonal polarized lights inclined at 45 degrees with respect to the incident surface separated by the above means,
By totally reflecting one side and converting it into elliptical polarized light whose major axis direction is parallel to the polarization direction of the other linearly polarized light, the polarization directions of the two separated polarized lights can be almost aligned. (The detailed principle of converting natural light into one polarization direction will be described later.)
【００２４】以上説明したように、第２のプリズム２を
経て偏光板７に入射する光はほぼ１方向の偏光方向を持
った偏光となっており、これまで自然光の約５０％を偏
光板７によって吸収されていた場合に比べて外光利用効
率を上げ、より明るい画面を提供することができ、しか
も偏光ビームスプリッターや膜蒸着を行わないので安価
に製造することができた。As described above, the light that enters the polarizing plate 7 through the second prism 2 is polarized light having a polarization direction of approximately one direction, and so far about 50% of natural light has been polarized plate 7. As compared with the case where it is absorbed by, the efficiency of using external light can be improved, a brighter screen can be provided, and since the polarization beam splitter and the film deposition are not performed, it can be manufactured at low cost.
【００２５】（自然光をある１つの偏光方向に変換する
原理）図２を用いて自然光をある１つの偏光方向に変換
する原理について説明する。偏光分離素子３′に入射し
た入射自然光４′は、直線偏光の偏光方向を入射自然光
４′の進行方向と偏光分離素子３′の法線の為す入射面
１１に対して、４５度傾いた偏光方向を持つ互いに直交
した偏光光（透過偏光光５′および反射偏光光６′）に
分離される。(Principle of Converting Natural Light into One Polarization Direction) The principle of converting natural light into one polarization direction will be described with reference to FIG. The incident natural light 4 ', which is incident on the polarization separation element 3', is a polarization that is inclined by 45 degrees with respect to the incident surface 11 that makes the polarization direction of linearly polarized light the traveling direction of the incident natural light 4'and the normal line of the polarization separation element 3 '. It is separated into polarized light (transmissive polarized light 5'and reflected polarized light 6 ') that are orthogonal to each other and have directions.
【００２６】分離された２つの直交する偏光光のうち反
射された反射偏光光６′は、全反射面１２（第１のプリ
ズム１の表面Ｂ２）によって全反射され、これによって
その長軸方向が偏光分離素子３′を透過した透過偏光光
５′の偏光方向とほぼ平行な楕円偏光光となり、透過偏
光光５′の偏光方向の光とほぼ偏光方向が揃えられるこ
とになる。従って自然光をほぼ同一の偏光方向を持つ偏
光光に変換することができる。The reflected polarized light 6'reflected out of the two separated orthogonally polarized lights is totally reflected by the total reflection surface 12 (the surface B2 of the first prism 1), so that its major axis direction is changed. It becomes elliptically polarized light that is substantially parallel to the polarization direction of the transmitted polarized light 5 ′ that has passed through the polarization separation element 3 ′, and the polarization direction of the transmitted polarized light 5 ′ is substantially aligned with that of the transmitted polarized light 5 ′. Therefore, natural light can be converted into polarized light having substantially the same polarization direction.
【００２７】例えば図１に示すように、第１のプリズム
１、第２のプリズム２の屈折率１．５２、両プリズムの
各角度を９０°、１５°、７５°としたとき、第１のプ
リズム１の表面の法線に対し２０°で入射した入射自然
光４は、第１のプリズム１の表面の法線に対し１３°に
屈折し、偏光分離素子３の偏光分離面３Ａの法線に対し
２８°で入射することになる。For example, as shown in FIG. 1, when the refractive indices of the first prism 1 and the second prism 2 are 1.52 and the angles of both prisms are 90 °, 15 ° and 75 °, respectively, The incident natural light 4 incident at 20 ° with respect to the normal line of the surface of the prism 1 is refracted at 13 ° with respect to the normal line of the surface of the first prism 1, and becomes the normal line of the polarization separation surface 3A of the polarization separation element 3. It will be incident at 28 °.
【００２８】偏光分離面３Ａで鏡面反射された反射偏光
光６は、第１のプリズム１の表面法線に対し４３°で入
射することになる。第１のプリズム１の屈折率は１．５
２なので、４１．１°を超える角度で入射した光は全反
射を起こすことになる。この結果反射偏光光は、直交し
た二つの偏光成分の間に３１．６°の位相差を生じ、楕
円率０．２８の楕円偏光光となり、透過偏光光５とほぼ
偏光方向が揃えられることになる。The reflected polarized light 6 specularly reflected by the polarization splitting surface 3 A is incident at 43 ° with respect to the surface normal of the first prism 1. The refractive index of the first prism 1 is 1.5
Since it is 2, light incident at an angle exceeding 41.1 ° will undergo total internal reflection. As a result, the reflected polarized light has a phase difference of 31.6 ° between two orthogonal polarized components, becomes elliptically polarized light with an ellipticity of 0.28, and the polarization direction of the transmitted polarized light 5 is substantially aligned. Become.
【００２９】上記した実施形態の光学素子Ｂは、１つの
偏光分離素子３をプリズム１、２が挟み込んだ場合につ
いて説明したが、それに限定されるものではなく、例え
ば図３に示すようにその法線方向を異にする複数の偏光
分離素子３を有する場合であってもよく、一体的に製造
する場合や、例えば１つの偏光分離素子３をプリズム
１、２で挟み込んだ光学素子Ｂを１セットとして、複数
セットを配列して平面状とする場合であってもよい。The optical element B of the above-described embodiment has been described with respect to the case where one polarization separation element 3 is sandwiched by the prisms 1 and 2, but the invention is not limited to this. For example, as shown in FIG. It may be a case in which a plurality of polarization separation elements 3 having different line directions are provided, and in the case of manufacturing integrally, for example, one set of optical element B in which one polarization separation element 3 is sandwiched between prisms 1 and 2 is used. Alternatively, a plurality of sets may be arrayed to form a flat surface.
【００３０】図３は、光学素子２Ｂの法線方向の断面図
を示している。光学素子２Ｂは、上記した実施の形態に
示された光学素子Ｂをプリズム部の角度Ｄ１からＤ４を
それぞれ変え、偏光分離素子３１から３４の４個配列し
た素子であり、これにより外光が複数方向から入射して
きたときも有効に光を変換することができ、従って外光
の利用効率を上げることができた。FIG. 3 shows a sectional view of the optical element 2B in the normal direction. The optical element 2B is an element obtained by arranging four of the polarization separating elements 31 to 34 by changing the angles D1 to D4 of the prism part of the optical element B shown in the above-mentioned embodiment, whereby a plurality of outside light is emitted. The light can be effectively converted even when the light is incident from the direction, and thus the utilization efficiency of external light can be improved.
【００３１】また同一面積の外光利用型直視液晶ディス
プレイについて、上記の実施の形態に示す光学素子Ｂよ
りも薄型、軽量化が可能なため、持ち運びできる携帯機
器などにも応用できる。また、液晶ディスプレイの大き
さに限定されることなく、汎用的な光学素子を構成でき
た。Further, the direct-view liquid crystal display using external light having the same area can be made thinner and lighter than the optical element B shown in the above-mentioned embodiment, so that it can be applied to a portable device which can be carried. Further, a general-purpose optical element could be constructed without being limited to the size of the liquid crystal display.
【００３２】尚、本実施の形態では、入射光として入射
自然光４により説明したが、それに限定するものではな
く、液晶表示装置外からの外光であればよい。In the present embodiment, the incident natural light 4 is used as the incident light, but the incident light is not limited to this, and may be external light from outside the liquid crystal display device.
【００３３】[0033]
【発明の効果】以上説明したように本発明は、自然光を
入射光進行方向と面の法線の為す入射面に対し、略４５
°の角度を持つ２つの直交した直線偏光光に分離し、分
離された光のうち反射光を全反射させて偏光を変換する
ことで、従来捨てていた一方の偏光方向の光を捨てず
に、高い効率で外光を利用することができるので簡単な
構成で明るく見やすい画面を表示することができるよう
になった。As described above, according to the present invention, the natural light is approximately 45 degrees with respect to the incident surface formed by the incident light traveling direction and the normal to the surface.
By splitting into two orthogonal linearly polarized lights with an angle of ° and totally reflecting the reflected light out of the separated light to convert the polarized light, the light of one polarization direction that was conventionally discarded is not discarded. Since it is possible to use outside light with high efficiency, it is possible to display a bright and easy-to-see screen with a simple configuration.
【図１】本発明の実施形態に係る液晶表示装置の縦断面
で示した説明図である。FIG. 1 is an explanatory diagram showing a vertical cross section of a liquid crystal display device according to an embodiment of the present invention.
【図２】本発明の実施形態に係る液晶表示装置における
原理の説明図である。FIG. 2 is an explanatory diagram of the principle of the liquid crystal display device according to the embodiment of the present invention.
【図３】本発明の実施形態に係る液晶表示装置に用いる
その他の光学素子１０２の縦断面図である。FIG. 3 is a vertical cross-sectional view of another optical element 102 used in the liquid crystal display device according to the embodiment of the present invention.
【図４】従来の液晶表示装置の縦断面図である。FIG. 4 is a vertical sectional view of a conventional liquid crystal display device.
Ａ 液晶表示装置 Ｂ、２Ｂ 光学素子 １ 第１プリズム ２ 第２プリズム ３、３１、３２、３３、３４ 偏光分離素子 ４ 入射自然光 ５ 透過偏光光 ６ 反射偏光光 ７ 偏光板 ８ ガラス ９ 液晶層 １０ 反射板 A liquid crystal display B, 2B optical element 1 first prism 2 second prism 3, 31, 32, 33, 34 Polarization separating element 4 incident natural light 5 Transmitted polarized light 6 Reflected polarized light 7 Polarizer 8 glass 9 Liquid crystal layer 10 Reflector
Claims (3)
ムと、 入射光を、入射面に対して４５°傾いた直線偏光と、前
記直線偏光と直交した直線偏光とに、一方を透過、他方
を反射させて分離する偏光分離素子と、 前記一方のプリズムに前記偏光分離素子を挟んで設ける
他方のプリズムとを備える 液晶表示装置であって、前記他方のプリズムは、前記偏光分離素子により反射さ
れた偏光光を、プリズム表面で内部全反射を生じさせる
とともに、内部全反射された偏光光を、前記偏光分離素
子を透過した直線偏光光と長軸方向が一致した楕円偏光
光に偏光する機能を備え、 前記分離された偏光光の偏光方向を揃えるようにした こ
とを特徴とする液晶表示装置。1. A liquid crystal display panel for displaying an image, and one prism provided on the exit side of the liquid crystal display panel.
And linearly polarized light incident on the incident plane by 45 °
For linearly polarized light and linearly polarized light orthogonal to each other, one is transmitted and the other is transmitted.
And a polarization separation element that reflects and separates the polarization separation element, and the polarization separation element is provided between the one prism.
A liquid crystal display device comprising the other prism , wherein the other prism is reflected by the polarization separation element.
Generated polarized light causes total internal reflection on the prism surface
At the same time, the polarized light totally internally reflected is
Elliptically polarized light whose long axis coincides with linearly polarized light that has passed through the element
A liquid crystal display device having a function of polarizing light so that the polarization directions of the separated polarized light are aligned .
を設けたことを特徴とする請求項１に記載の液晶表示装
置。2. A plurality of polarization separation elements having different normal directions.
The liquid crystal display device according to claim 1, further comprising:
偏光分離素子を挟み込んだプリズムを複数組、平面状に
組み合わせて構成することを特徴とする請求項１又は２
に記載の液晶表示装置。3. A prism in which a polarization separation element is sandwiched,
Multiple sets of prisms that sandwich the polarization separation element,
It is configured by combining them.
The liquid crystal display device according to item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18929698A JP3506914B2 (en) | 1998-07-03 | 1998-07-03 | Liquid crystal display |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18929698A JP3506914B2 (en) | 1998-07-03 | 1998-07-03 | Liquid crystal display |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000019505A JP2000019505A (en) | 2000-01-21 |
| JP3506914B2 true JP3506914B2 (en) | 2004-03-15 |
Family
ID=16238965
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18929698A Expired - Fee Related JP3506914B2 (en) | 1998-07-03 | 1998-07-03 | Liquid crystal display |
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| Country | Link |
|---|---|
| JP (1) | JP3506914B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6609795B2 (en) * | 2001-06-11 | 2003-08-26 | 3M Innovative Properties Company | Polarizing beam splitter |
| US20040227994A1 (en) * | 2003-05-16 | 2004-11-18 | Jiaying Ma | Polarizing beam splitter and projection systems using the polarizing beam splitter |
-
1998
- 1998-07-03 JP JP18929698A patent/JP3506914B2/en not_active Expired - Fee Related
Also Published As
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|---|---|
| JP2000019505A (en) | 2000-01-21 |
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