JP4632377B2 - Light guide plate, surface light source device, and liquid crystal display device - Google Patents

Light guide plate, surface light source device, and liquid crystal display device Download PDF

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JP4632377B2
JP4632377B2 JP2008128740A JP2008128740A JP4632377B2 JP 4632377 B2 JP4632377 B2 JP 4632377B2 JP 2008128740 A JP2008128740 A JP 2008128740A JP 2008128740 A JP2008128740 A JP 2008128740A JP 4632377 B2 JP4632377 B2 JP 4632377B2
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guide plate
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crystal display
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清司 梅本
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Nitto Denko Corp
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Description

本発明は、光利用効率に優れて輝度やその均一性に優れる面光源装置及び明るくて見やすい反射型や透過型の液晶表示装置を形成でき、発光色変換式などとすることもできる多光源型の導光板に関する。   The present invention is capable of forming a surface light source device having excellent light use efficiency and excellent brightness and uniformity, and a reflective and transmissive liquid crystal display device that is bright and easy to see, and can be a light source color conversion type. It relates to a light guide plate.

従来、導光板としては、板状体における上下面の一方に粗面や白色ドットを設け側面からの入射光を散乱させて上下面の他方に出射させるようにしたサイドライト型のものが知られていた。かかるサイドライト型導光板は、その側面に光源を配置して面光源装置としそれを液晶セルと組み合わせて反射型や透過型等の液晶表示装置の形成に用いられている。   Conventionally, as a light guide plate, a side light type is known in which a rough surface or white dots are provided on one of the upper and lower surfaces of a plate-like body, and incident light from the side surface is scattered and emitted to the other of the upper and lower surfaces. It was. Such a side light type light guide plate is used to form a reflection type or a transmission type liquid crystal display device by arranging a light source on the side surface to form a surface light source device and combining it with a liquid crystal cell.

しかしながら、輝度やその均一性に乏しくて表示品位に乏しい問題点があった。複数の側面に光源を配置して輝度を向上させる提案もあるが輝度のバラツキは改善されにくい。また液晶表示装置は、液晶セルに対する面光源装置の配置位置でバックライト式とフロントライト式に区別されているが、前記の散乱式では表示像を乱すためにフロントライト式で用いることが困難な問題点もあった。かかるフロントライト式では、液晶表示装置の携帯電話などへの普及に伴いバックライト式の場合と同様に発光色を変換できるものも求められている。   However, there is a problem that the display quality is poor due to poor brightness and uniformity. There is also a proposal for improving the luminance by arranging light sources on a plurality of side surfaces, but variations in luminance are difficult to improve. In addition, the liquid crystal display device is distinguished from the backlight type and the front light type in the arrangement position of the surface light source device with respect to the liquid crystal cell, but the scattering type described above is difficult to use in the front light type because the display image is disturbed. There was also a problem. In such a front light type, with the spread of liquid crystal display devices to cellular phones and the like, there is also a demand for a device that can convert the emission color as in the case of the backlight type.

本発明は、光の利用効率に優れて輝度とその均一性に優れる面光源装置を用いた明るくて見やすく、発光色変換式とすることも可能なフロントライト式で反射型液晶表示装置開発を課題とする。 The present invention is excellent in light utilization efficiency of luminance and easy rather look bright using a surface light source device excellent in the uniformity of the reflection type liquid crystal display device in possible front lit be a light emitting color conversion formulas Development is an issue.

本発明は、上面と下面とその上下面間の側面からなる2面の入射側面を少なくとも有する板状体よりなり、その入射側面が板状体の左右方向と前後方向の側面からなると共に、前記上面に各入射側面からの入射光を下面に出射するための光出射手段を有して、その光出射手段が伝送光反射面とその対向面からなり各入射側面に沿う方向の稜線を有するプリズム状凹凸の80μm〜1mmの一定ピッチによる繰返し構造よりなり、前記伝送光反射面が前記下面の基準平面に対し傾斜角30〜45度で入射側面に対面し当該基準平面に対する投影幅が3〜40μmの斜面からなると共に、前記対向面が当該基準平面に対する傾斜角40度以上の斜面よりなる導光板の各入射側面に光源を配置してなる面光源装置における当該導光板の下面側に、反射層具備の液晶セルを有することを特徴とする液晶表示装置を提供するものである。 The present invention comprises a plate-like body having at least two incident side surfaces composed of an upper surface, a lower surface, and a side surface between the upper and lower surfaces. has a light emitting means for emitting incident light from the incident side to the lower surface to the upper surface, a prism to which the light emitting means has a ridge line in a direction along the respective incident side consists opposing faces thereof with the transmission light reflecting surface consists repetitive structure with a constant pitch of 80μm~1mm of Jo irregularities, the projected width the transmission light reflecting surface for facing to the reference plane to the incident side surface at an inclination angle of 30-45 degrees with respect to a reference plane of said lower surface is 3~40μm together with consisting slope on the lower surface of the light guide plate in a surface light source device formed by arranging the light source to the respective incident side of the opposing surface is Ru light guide plate name than the inclination angle of 40 degrees or more slopes with respect to the reference plane, reflector Layering tool There is provided a liquid crystal display device characterized by having a liquid crystal cell.

本発明によれば、導光板の少なくとも2側面より光源からの光を入射させ、その入射光をプリズム状凹凸の繰返し構造よりなる光出射手段を介して同一面より出射させるようにしたので光源からの光を効率よく面光源に変換して輝度とその均一性に優れる面光源装置を得ることができ、それをフロントライトに用いて明るくて見やすい反射型の液晶表示装置を形成することができる。また異色発光の光源の組合せとして発光色の変換が可能なフロントライト式の液晶表示装置も形成することができる。 According to the present invention, the light from the light source is incident from at least two side surfaces of the light guide plate, and the incident light is emitted from the same surface via the light emitting means having a repetitive structure of prismatic irregularities. Can be efficiently converted into a surface light source to obtain a surface light source device having excellent luminance and uniformity, and a bright and easy-to-view reflective liquid crystal display device can be formed by using it as a front light . In addition, a front-light type liquid crystal display device capable of changing the emission color can be formed as a combination of light sources emitting different colors.

本発明の液晶表示装置に用いる導光板は、上面と下面とその上下面間の側面からなる2面の入射側面を少なくとも有する板状体よりなり、その入射側面が板状体の左右方向と前後方向の側面からなると共に、前記上下面の一方に各入射側面からの入射光を上下面の他方に出射するための光出射手段を有して、その光出射手段が各入射側面に沿う方向の稜線を有するプリズム状凹凸の繰返し構造よりなるものである。その例を図1、図2に示した。1が導光板を形成する板状体であり、11が上面、13a、bが入射側面である。なお下面12は、図3の如く上面11の対向位置にある。 The light guide plate used in the liquid crystal display device of the present invention is composed of a plate-like body having at least two incident side surfaces composed of an upper surface, a lower surface, and side surfaces between the upper and lower surfaces, and the incident side surfaces are in the left-right direction and front-back direction And a light emitting means for emitting incident light from each incident side surface to the other of the upper and lower surfaces, the light emitting means in a direction along each incident side surface. It consists of a repeating structure of prismatic irregularities having ridge lines. Examples thereof are shown in FIGS. Reference numeral 1 denotes a plate-like body forming a light guide plate, 11 denotes an upper surface, and 13a and 13b denote incident side surfaces. The lower surface 12 is at a position facing the upper surface 11 as shown in FIG.

入射側面は、それに光源を配置して光を入射させることを目的とし、本発明においては図1、2の例の如く板状体1の左右方向13aと前後方向13bの側面の組合せにて板状体の上下面間における側面の少なくとも2面が入射側面13a、bとして利用される。これにより2面以上の側面より別体の光源を介して光を入射させることができ、輝度の向上や発光色の変換が可能となる。   The incident side surface is intended to allow light to enter by placing a light source on the incident side surface. In the present invention, as shown in the examples of FIGS. At least two of the side surfaces between the upper and lower surfaces of the shaped body are used as the incident side surfaces 13a and 13b. As a result, light can be incident from two or more side surfaces through separate light sources, and luminance can be improved and emission colors can be converted.

一方、板状体の上下面の一方に形成する光出射手段は、入射側面からの入射光を上下面の他方に出射するためのものであり、本発明においては図3、図4に例示のAの如くプリズム状凹凸の繰返し構造にて形成され、かつ図1、2に例示の如くそのプリズム状凹凸の稜線A、Bが入射側面13a、bに沿う方向となるように形成される。なお図4の導光板1では、図2におけるα−β断面、γ−δ断面による概略を示している。   On the other hand, the light emitting means formed on one of the upper and lower surfaces of the plate-like body is for emitting incident light from the incident side surface to the other of the upper and lower surfaces. In the present invention, it is exemplified in FIGS. As shown in FIG. 1 and FIG. 2, the prism-shaped unevenness ridgelines A and B are formed in a direction along the incident side surfaces 13 a and b. In addition, in the light-guide plate 1 of FIG. 4, the outline by the (alpha) -beta cross section in FIG. 2 and a (gamma) -delta cross section is shown.

前記により入射側面のそれぞれに対応した光出射手段を配置でき、上下面の一方を共通の光出射面として光を指向性よく出射させることができて光利用効率の向上等を図ることができる。なお図例では上面11に光出射手段を有して下面12より出射するもの、従って下面が光出射面となるものを示している。導光板の厚さを介し光路長を増大して光出射手段を介した出射光の輝線化を緩和して平準化し、発光の均一性の向上を図る点よりは図例の如く板状体の上面に光出射手段を形成して下面を光出射面としたものが好ましく、特にフロントライト式とする場合に好ましい。   As described above, the light emitting means corresponding to each of the incident side surfaces can be arranged, and one of the upper and lower surfaces can be used as a common light emitting surface to emit light with good directivity, thereby improving the light utilization efficiency. In the example shown in the figure, a light emitting means is provided on the upper surface 11 and the light is emitted from the lower surface 12, so that the lower surface becomes the light emitting surface. From the point of increasing the optical path length through the thickness of the light guide plate and relaxing and leveling the bright line of the outgoing light through the light emitting means, the uniformity of the light emission is improved as shown in the figure. It is preferable that the light emitting means is formed on the upper surface and the lower surface is the light emitting surface, particularly in the case of a front light type.

光利用効率等の点より好ましい光出射手段は、入射側面からの入射光を反射、特に全反射を介して光出射面側に光路制御しうるようにした斜面を有するものである。かかる斜面を有するプリズム状凹凸は、等辺面等からなる適宜な凹凸構造にて形成することができる。   A light emitting means that is preferable from the viewpoint of light use efficiency and the like has an inclined surface that can reflect the incident light from the incident side surface, and in particular, can control the optical path to the light emitting surface side through total reflection. The prism-like unevenness having such a slope can be formed with an appropriate uneven structure composed of equilateral surfaces or the like.

好ましいプリズム状凹凸の構造は、導光板の光出射面よりその基準平面の垂直(法線)方向に可及的に多くの光が出射すると共に、反射型液晶表示装置のフロントライトとする場合には表示光となる前記出射光と導光板よりの漏れ光の方向が可及的に重複しないものである。漏れ光が表示光と重複すると表示像の強さを減殺してコントラストの低下原因となりやすい。   The prism-shaped uneven structure is preferably used when a light is emitted as much as possible in the vertical (normal) direction of the reference plane from the light emitting surface of the light guide plate and is used as a front light of a reflective liquid crystal display device. The direction of the emitted light which becomes display light and the light leakage from the light guide plate do not overlap as much as possible. If the leaked light overlaps with the display light, the strength of the display image is diminished and the contrast tends to be lowered.

前記した出射光の法線方向化や漏れ光と表示光の重複防止性の点より好ましい凹凸は、図3に例示した如く導光板の上下面の光出射手段を有しない側、すなわち光出射面となる側の基準平面に対する傾斜角θ1が30〜45度の伝送光反射面A1と、それに対向する当該傾斜角θ2が40度以上の面A2からなるものである。   The unevenness that is preferable from the viewpoint of normalizing the emitted light and preventing the overlapping of leakage light and display light is the side having no light emitting means on the upper and lower surfaces of the light guide plate as illustrated in FIG. The transmission light reflecting surface A1 having an inclination angle θ1 of 30 to 45 degrees with respect to the reference plane on the opposite side and the surface A2 having an inclination angle θ2 opposite thereto of 40 degrees or more.

前記の伝送光反射面A1は、入射側面よりの入射光の内、その面に入射する光を反射して光出射面に供給する役割をする。その場合に当該傾斜角を30〜45度とすることにより伝送光を光出射面に対し垂直性よく反射して表示に有利な出射光を効率よく得ることができる。スネルの法則に基づく全反射や漏れ光の抑制、それによる視認妨害の抑制等の前記した性能などの点より伝送光反射面の好ましい傾斜角は、35〜44度、就中38〜43度である。   The transmission light reflecting surface A1 serves to reflect the light incident on the incident light from the incident side surface and supply it to the light emitting surface. In this case, by setting the tilt angle to 30 to 45 degrees, the transmitted light can be reflected with good perpendicularity to the light exit surface, and the emitted light that is advantageous for display can be obtained efficiently. From the viewpoint of the above-mentioned performance such as suppression of total reflection and leakage light based on Snell's law, and suppression of visual interference thereby, the preferable inclination angle of the transmission light reflecting surface is 35 to 44 degrees, especially 38 to 43 degrees. is there.

伝送光反射面の傾斜角が30度未満では光出射面よりの出射光の方向が法線に対して大きい角度となり、視認に有効利用できる光量が減少して明るさが低下しやすい。また45度を超えると光出射手段形成面よりの漏れ光が増大して表示像のコントラストが低下しやすくなる。   If the transmission light reflecting surface has an inclination angle of less than 30 degrees, the direction of the emitted light from the light emitting surface becomes a large angle with respect to the normal, and the amount of light that can be effectively used for visual recognition is reduced, so that the brightness tends to decrease. On the other hand, if it exceeds 45 degrees, the leakage light from the light emitting means forming surface increases and the contrast of the display image tends to decrease.

一方、対向面A2は、伝送光反射面の形成に伴って不可避的に発生する面であり、その面の上記基準平面に対する投影幅でプリズム状凹凸間の面部分が可及的に狭くならないことが好ましい。すなわち図上のプリズム状凹凸間の上面部分11aは、反射型液晶表示装置のフロントライトとした場合には液晶セルからの表示像を透過させる部分、透過型液晶表示装置のバックライトとした場合には反射層等を介した反射光を透過させる部分として機能することより対向面A2の当該投影幅で前記の上面部分11aが狭くなると視認性や光利用効率を低下させる。   On the other hand, the facing surface A2 is a surface that is inevitably generated along with the formation of the transmission light reflecting surface, and the surface portion between the prismatic irregularities is not made as narrow as possible with the projection width of the surface with respect to the reference plane. Is preferred. That is, the upper surface portion 11a between the prism-shaped projections and depressions in the figure is a portion that transmits the display image from the liquid crystal cell when the front light of the reflective liquid crystal display device is used, and the backlight portion of the transmissive liquid crystal display device. Functions as a portion that transmits reflected light through a reflective layer or the like, and when the upper surface portion 11a becomes narrower with the projection width of the facing surface A2, visibility and light utilization efficiency are lowered.

従って対向面の当該投影幅は、プリズム状凹凸間の面部分を可及的に狭くしないものであることが好ましい。かかる点より対向面の当該基準平面に対する傾斜角θ2は、40度以上、就中50度以上、特に60度以上とすることが好ましく、90度以上の傾斜角として対向面の当該投影幅が0となるか伝送光反射面の当該投影幅とオーバーラップするようにすることもできる。   Therefore, it is preferable that the projection width of the opposing surface does not make the surface portion between the prism-shaped irregularities as narrow as possible. From this point, the inclination angle θ2 of the opposing surface with respect to the reference plane is preferably 40 degrees or more, more preferably 50 degrees or more, particularly 60 degrees or more, and the projection width of the opposing surface is 0 as an inclination angle of 90 degrees or more. It can also be made to overlap with the projection width of the transmission light reflecting surface.

上記の如く光出射手段を形成するプリズム状凹凸の伝送光反射面とその対向面の当該傾斜角を調節することにより、出射光に高度な指向性をもたせることができて、それにより光出射面に対して垂直方向ないしそれに近い角度で光を出射させることが可能になる。なお光出射手段を形成するプリズム状凹凸の斜面は、直線面や屈折面、湾曲面等を含む適宜な面形態に形成でき、形状等の異なるプリズム状凹凸の繰返し構造とすることもできる。またプリズム状凹凸は、その稜線が連続した一連の凹凸構造に形成されていてもよいし、所定の間隔を有して稜線方向に不連続に配列した断続的な凹凸構造に形成されていてもよい。   By adjusting the angle of inclination of the transmission light reflecting surface of the prism-shaped unevenness and the opposing surface forming the light emitting means as described above, it is possible to give the outgoing light a high degree of directivity, and thereby the light emitting surface. It is possible to emit light in a direction perpendicular to or at an angle close thereto. The slopes of the prismatic irregularities forming the light emitting means can be formed in an appropriate surface form including a straight surface, a refracting surface, a curved surface, etc., and can also have a repeating structure of prismatic irregularities having different shapes. Also, the prism-like unevenness may be formed in a series of uneven structures whose ridge lines are continuous, or may be formed in an intermittent concavo-convex structure arranged discontinuously in the ridge line direction with a predetermined interval. Good.

前記したプリズム状凹凸間の面部分の面積を確保し、液晶セルの画素との干渉によるモアレの発生を防止することやシャープな凹凸の形成性などの点より好ましい伝送光反射面の大きさは、液晶セルの画素ピッチが100〜300μmが一般的であることを考慮して、光出射面の基準平面に対する投影幅に基づいて40μm以下、就中3〜20μm、特に5〜15μmである。   The size of the transmission light reflecting surface that is preferable in terms of securing the area of the surface portion between the prism-like irregularities described above, preventing the occurrence of moire due to interference with the pixels of the liquid crystal cell, and forming sharp irregularities, etc. Considering that the pixel pitch of the liquid crystal cell is generally 100 to 300 μm, it is 40 μm or less, especially 3 to 20 μm, especially 5 to 15 μm based on the projection width of the light emitting surface with respect to the reference plane.

また前記の点より伝送光反射面の間隔は大きいことが好ましいが、一方で伝送光反射面は上記したように側面入射光の実質的な出射機能部分であるから、その間隔が広すぎると照明光が疎となってやはり不自然な表示となる場合があり、それらを鑑みた場合、プリズム状凹凸の繰返しピッチP(図3)は、80μm〜1mmとすることが好ましい。なおピッチは、例えばランダムピッチや所定数のピッチ単位をランダム又は規則的に組合せたものなどの如く不規則であってもよいが、モアレの防止性や外観性等の点よりは一定であることが好ましい。   In addition, it is preferable that the interval between the transmission light reflecting surfaces is larger than the above point, but on the other hand, the transmission light reflecting surface is a substantial emission function part of the side incident light as described above. In some cases, the light becomes sparse and unnatural display may occur. In view of these, it is preferable that the repetitive pitch P (FIG. 3) of the prism-shaped irregularities is 80 μm to 1 mm. The pitch may be irregular, such as a random pitch or a random or regular combination of a predetermined number of pitch units, but the pitch is constant in terms of moire prevention and appearance. Is preferred.

さらに明るい表示像を得る点よりプリズム状凹凸の繰返しピッチは、光出射面の基準平面に対する伝送光反射面の投影幅の8倍以上、就中10倍以上、特に12倍以上であることが好ましい。これにより反射型液晶表示装置のフロントライトとした場合には液晶セルによる表示像の大部分をプリズム状凹凸の繰返しピッチ間における上面又は下面の部分を介して透過させることができる。また透過型液晶表示装置のバックライトとした場合には、大きい面積の反射面や透過面を確保できて光利用効率の向上に有利である。   From the standpoint of obtaining a brighter display image, the repetitive pitch of the prism-shaped irregularities is preferably 8 times or more, more preferably 10 times or more, especially 12 times or more, the projection width of the transmission light reflecting surface with respect to the reference plane of the light emitting surface. . As a result, when the front light of the reflective liquid crystal display device is used, most of the display image by the liquid crystal cell can be transmitted through the upper or lower surface portion between the repetitive pitches of the prismatic irregularities. Further, when a backlight of a transmissive liquid crystal display device is used, a large-area reflective surface and transmissive surface can be secured, which is advantageous in improving light utilization efficiency.

プリズム状凹凸の繰返し構造からなる光出射手段の場合、液晶セルの画素と干渉してモアレを生じる場合がある。モアレの防止は、凹凸のピッチ調節で行いうるが、上記したように凹凸のピッチには好ましい範囲がある。従ってそのピッチ範囲でモアレが生じる場合の解決策としては、画素に対し凹凸を交差状態で配列しうるように凹凸を入射側面の基準平面に対し傾斜状態に形成する方式が好ましい。その場合、傾斜角が大きすぎると伝送光反射面等を介した反射に偏向を生じて出射光の方向に大きな偏りが発生し、導光板の光伝送方向における発光強度の異方性が大きくなって光利用効率も低下し、表示品位の低下原因となりやすい。   In the case of a light emitting means having a prismatic uneven structure, it may interfere with the pixels of the liquid crystal cell to cause moire. Moire can be prevented by adjusting the uneven pitch, but as described above, there is a preferable range for the uneven pitch. Therefore, as a solution when moire occurs in the pitch range, a method in which the unevenness is formed in an inclined state with respect to the reference plane of the incident side surface so that the unevenness can be arranged in a crossing manner with respect to the pixel is preferable. In that case, if the inclination angle is too large, the reflection through the transmission light reflecting surface or the like is deflected, resulting in a large deviation in the direction of the emitted light, and the anisotropy of the emission intensity in the light transmission direction of the light guide plate increases. As a result, the light utilization efficiency is also lowered, and the display quality is likely to be lowered.

前記の点より入射側面の基準平面に対するプリズム状凹凸の配列方向、すなわちプリズム状凹凸の稜線方向の傾斜角θa、bは、±30度以内、就中±25度以内、特に±20度以内とすることが好ましい。なお±の符号は、入射側面を基準とした傾斜の方向を意味する。モアレを無視しうる場合などには図1の例の如くプリズム状凹凸の配列方向は、入射側面に平行なほど好ましい。   The inclination direction θa, b of the prism-shaped unevenness with respect to the reference plane of the incident side surface from the above point, that is, the inclination angle θa, b in the ridge line direction of the prism-shaped unevenness is within ± 30 degrees, in particular within ± 25 degrees, in particular within ± 20 degrees. It is preferable to do. The sign of ± means the direction of inclination with respect to the incident side surface. When moiré can be ignored, the arrangement direction of the prismatic irregularities is preferably as parallel to the incident side surface as in the example of FIG.

上記においては、一の入射側面に対する光出射手段について説明したが、本発明においては各入射側面に対応する各光出射手段が上記を満足することが好ましい。ただしプリズム状凹凸の構造やピッチは、各光出射手段で同じである必要はなく、導光板や画素サイズの左右方向や前後方向の寸法などに応じて適宜に決定することができる。   In the above description, the light emitting means for one incident side surface has been described. In the present invention, it is preferable that each light emitting means corresponding to each incident side surface satisfies the above. However, the structure and pitch of the prismatic unevenness need not be the same for each light emitting means, and can be determined as appropriate according to the light guide plate, the pixel size in the left-right direction, the front-rear direction, and the like.

また本発明においては、図1、2の例の如く板状体1の左右方向の光出射手段Aと前後方向の光出射手段Bが交差することとなるが、その場合、前記したモアレ防止等の点より各入射側面に対して設けた光出射手段としてのプリズム状凹凸の稜線が40度以上、就中60度以上の角度で交差することが好ましい。   In the present invention, the light emitting means A in the left-right direction and the light emitting means B in the front-rear direction of the plate-like body 1 intersect as in the examples of FIGS. From this point, it is preferable that the ridge lines of the prismatic unevenness as the light emitting means provided for each incident side surface intersect at an angle of 40 degrees or more, especially 60 degrees or more.

導光板は、適宜な形態としうるが、一般には左右方向と前後方向の入射側面を確保する点より図例の如く入射側面13a、bとそれに対面する対向端14a、bの厚さが同厚の板とされる。導光板の光出射面、すなわち光出射手段を形成しない上下面の一方は、通例フラット面とされるが、反射型液晶表示装置のフロントライトとして上面から視認した場合に視認方向により、光出射手段とそれが光出射面に映込んだパターン同士が干渉して干渉縞によるモアレ現象を発生するときがあり、そのモアレによる表示品位の低下防止を目的に必要に応じ微細凹凸を付与した光出射面構造などとすることもできる。   The light guide plate can have any suitable form, but in general, the incident side surfaces 13a and 13b and the opposing ends 14a and 14b facing each other have the same thickness as shown in the figure from the viewpoint of securing the left and right and front and rear incident side surfaces. It is made of a board. The light exit surface of the light guide plate, that is, one of the upper and lower surfaces that do not form the light exit means is usually a flat surface, but the light exit means depends on the viewing direction when viewed from the top as a front light of a reflective liquid crystal display device. And the pattern reflected on the light exit surface may interfere with each other to generate a moire phenomenon due to interference fringes. The light exit surface is provided with fine irregularities for the purpose of preventing deterioration of display quality due to the moire. It can also be a structure or the like.

前記した光出射面における微細凹凸の形成は、例えばサンドブラスト等のマット処理による粗面化方式や導光板を形成する際に金型等を介して微細凹凸を付与する方式、透明粒子含有の樹脂層を付設する方式や拡散ドットないしそれを設けたシートを導光板に設ける方式などの従来の拡散層に準じた適宜な方式にて行うことができる。   The formation of the fine irregularities on the light exit surface described above is, for example, a roughening method by mat processing such as sandblasting, a method of giving fine irregularities through a mold or the like when forming a light guide plate, a resin layer containing transparent particles Can be performed by an appropriate method in accordance with a conventional diffusion layer, such as a method of attaching a diffusion dot or a method of providing a diffusion dot or a sheet provided with it on a light guide plate.

導光板における入射側面等の側面の形状についても、特に限定はなく適宜に決定してよい。一般には光源の配置性などの点より光出射面に対して垂直な入射側面とされるが、陰極管の外形に対応した凹形などとすることもできる。また入射側面は、図2に例示した如く透明体15a、bを介して突出した形態に形成することもできる。かかる突出形態は、左右方向13aと前後方向13bに配置することとなる光源の電極部等による非発光部の空間的な干渉を防ぐことや、光路長を増大して光源長の不足(短寸)による端部等での発光ムラの発生を防止することなどを目的とする。   The shape of the side surface such as the incident side surface of the light guide plate is not particularly limited and may be appropriately determined. In general, the incident side surface is perpendicular to the light exit surface from the viewpoint of the arrangement of the light source, but it may be a concave shape corresponding to the outer shape of the cathode tube. Further, the incident side surface can be formed in a form protruding through the transparent bodies 15a and 15b as illustrated in FIG. Such a protruding form prevents spatial interference of the non-light emitting part due to the electrode part of the light source which is disposed in the left-right direction 13a and the front-rear direction 13b, or increases the optical path length and the light source length is insufficient (short dimension). ) To prevent the occurrence of light emission unevenness at the end or the like.

前記した突出形態の場合、そこに配置する光源との関係では前記の如く発光ムラの防止等に寄与するが、他方に配置する光源との関係ではその突出部分に光が入射しにくくなり影が発生しやすくなる。すなわち図2の例では左右方向の突出部15aでは前後方向の光源からの光が入射しにくくなり、前後方向の突出部15bでは左右方向の光源からの光が入射しにくくくなって、その突出部分で影が発生しやすくなる。   In the case of the protruding form described above, the relationship with the light source arranged there contributes to the prevention of uneven emission as described above, but in the relationship with the light source arranged on the other side, it is difficult for light to enter the protruding part and a shadow is formed. It tends to occur. That is, in the example of FIG. 2, the light from the light source in the front-rear direction is less likely to be incident on the protrusion 15a in the left-right direction, and the light from the light source in the left-right direction is less likely to be incident on the protrusion 15b in the front-rear direction. Shadows are likely to occur at the part.

本発明においては、前記に対して光出射手段のプリズム状凹凸の稜線を傾斜させることにより影の発生を防止することができる。すなわち図2に例示した如く左右方向の入射側面13aに対して設けた光出射手段Aについては、そのプリズム状凹凸の稜線がその左右方向の入射側面を基準に前後方向の入射側面13bの側より他端14bの側に遠離る方向に傾斜θaさせることにより、前後方向の入射側面13bに対して設けた光出射手段Bについては、そのプリズム状凹凸の稜線がその前後方向の入射側面を基準に左右方向の入射側面13aの側より他端14aの側に遠離る方向に傾斜θbさせることにより、伝送光反射面を介した出射光を前記した影となる突出部分の方向に出射させて影となることによる発光不足を補うことにより防止することができる。   In the present invention, the occurrence of shadows can be prevented by inclining the ridges of the prismatic irregularities of the light emitting means relative to the above. That is, as illustrated in FIG. 2, with respect to the light emitting means A provided on the left and right incident side surface 13a, the ridge line of the prism-shaped irregularities is from the side of the front and rear direction incident side surface 13b with respect to the left and right direction incident side surface. With respect to the light emitting means B provided on the incident side surface 13b in the front-rear direction by making the inclination θa away from the other end 14b, the ridge line of the prism-shaped unevenness is based on the incident side surface in the front-rear direction. By tilting θb in a direction away from the side of the incident side surface 13a in the left-right direction toward the other end 14a, the outgoing light through the transmission light reflecting surface is emitted in the direction of the protruding portion that becomes the shadow, and the shadow This can be prevented by compensating for the lack of light emission.

導光板の形成には、光源の波長域に応じそれに透明性を示す適宜な材料を用いうる。ちなみに可視光域では、例えばアクリル系樹脂やポリカーボネート系樹脂、ポリエステル系樹脂やノルボルネン系樹脂、ポリオレフィン系樹脂やエポキシ系樹脂等で代表される透明樹脂やガラスなどがあげられる。複屈折を示さないか、複屈折の小さい材料で形成したものが好ましい。   For the formation of the light guide plate, an appropriate material showing transparency can be used according to the wavelength range of the light source. Incidentally, in the visible light range, for example, acrylic resins, polycarbonate resins, polyester resins, norbornene resins, transparent resins represented by polyolefin resins, epoxy resins, and the like can be used. Those formed of a material that does not exhibit birefringence or has low birefringence are preferable.

導光板は、切削法にても形成でき、適宜な方法で形成することができる。量産性等の点より好ましい製造方法としては、熱可塑性樹脂を所定の形状を形成しうる金型に加熱下に押付て形状を転写する方法、加熱溶融させた熱可塑性樹脂あるいは熱や溶媒を介して流動化させた樹脂を所定の形状に成形しうる金型に充填する方法、熱や紫外線ないし放射線等で重合処理しうる液状樹脂を所定の形状を形成しうる型に充填ないし流延して重合処理する方法などがあげられる。   The light guide plate can be formed by a cutting method and can be formed by an appropriate method. As a preferable production method from the viewpoint of mass productivity, etc., a method of transferring a shape by pressing a thermoplastic resin to a mold capable of forming a predetermined shape under heating, a heat-melted thermoplastic resin, or via a heat or solvent A method of filling a fluidized resin into a mold that can be molded into a predetermined shape, filling or casting a liquid resin that can be polymerized with heat, ultraviolet light, radiation, or the like into a mold that can form a predetermined shape Examples thereof include a polymerization method.

導光板の厚さは、使用目的による導光板のサイズや光源の大きさなどにより適宜に決定することができる。反射型や透過型の液晶表示装置等の形成に用いる場合の一般的な導光板の厚さは、その入射側面に基づき20mm以下、就中0.1〜10mm、特に0.3〜5mmである。なお導光板は、例えば光の伝送を担う導光部に光出射手段を形成したシートを接着したものの如く、同種又は異種の材料からなる部品の積層体などとして形成されていてもよく、1種の材料による一体的単層物として形成されている必要はない。   The thickness of the light guide plate can be appropriately determined depending on the size of the light guide plate and the size of the light source depending on the purpose of use. The thickness of a general light guide plate when used to form a reflective or transmissive liquid crystal display device is 20 mm or less, especially 0.1 to 10 mm, especially 0.3 to 5 mm, based on the incident side surface. . The light guide plate may be formed as a laminated body of parts made of the same or different materials, such as a sheet in which a light emitting means is bonded to a light guide portion that carries light transmission. It is not necessary to be formed as an integral single layer of the above materials.

本発明の液晶表示装置用の面光源装置は、反射型や透過型の液晶表示装置等におけるサイドライト型のフロントライトやバックライトなどとして用いることを目的に、図4や図5に例示の如く導光板1における入射側面13a、bのそれぞれに光源21を配置したものである。その光源については、特に限定はなく面光源装置の使用目的などに応じて単色光や各種波長域の発光特性を示す適宜なものを用いうる。 The surface light source device for a liquid crystal display device of the present invention is used as a sidelight type front light or backlight in a reflective or transmissive liquid crystal display device or the like, as illustrated in FIG. 4 or FIG. A light source 21 is disposed on each of the incident side surfaces 13 a and 13 b of the light guide plate 1. The light source is not particularly limited, and a suitable light source that exhibits monochromatic light or light emission characteristics in various wavelength ranges can be used according to the purpose of use of the surface light source device.

ちなみに前記光源の例としては、(冷、熱)陰極管や発光ダイオード等の点状光源、その点状光源のアレイ体や点状光源による光を線状光源化したもの、細長のエレクトロルミネッセンス素子などがあげられる。液晶表示装置の形成に用いる面光源装置では、可視光域の可及的に広い波長域の発光特性を示すものが好ましい。導光板に配置する光源の組合せは、例えば同種のものや発光色が相違するものなどの如く使用目的に応じて適宜に決定することができる。また光源は、適宜な方式にてそれぞれを独立に又は従属的に点灯と消灯を切り替え得るようにすることもできる。   By the way, examples of the light source include point light sources such as (cold and heat) cathode tubes and light emitting diodes, an array of the point light sources, light obtained from the point light source into a linear light source, and an elongated electroluminescence element. Etc. As the surface light source device used for forming the liquid crystal display device, one that exhibits light emission characteristics in a wavelength region as wide as possible in the visible light region is preferable. The combination of the light sources arranged on the light guide plate can be appropriately determined according to the purpose of use, for example, the same type or the different light emission colors. In addition, the light sources can be switched on and off independently or independently by an appropriate method.

就中、低消費電力性や光源駆動装置等の簡便化、点灯/消灯切り替えの方式の簡便化や異色発光光源の組込みの容易性などの点より発光ダイオード、特にそれを用いて線状光源を得るようにしたものが好ましい。ちなみにその例としては、上記の導光板に準じて入射側面に配置し得るように形成した直方体等からなる線状の導光板の背面や側面に点状光源を配置して、点状光源からの入射光を線状光源に変換できるようにしたものなどがあげられる。その場合、線状導光板の側面に点状光源を配置する方式では線状導光板の背面にドット構造やプリズム状凹凸の繰返し構造等からなる適宜な形態の光路変更手段などを設けることもできる。   In particular, light-emitting diodes, especially linear light sources using them, are considered in terms of low power consumption, simplification of light source driving devices, simplification of switching on / off, and ease of incorporation of different color light sources. What was obtained is preferable. By the way, as an example, a point light source is arranged on the back and side of a linear light guide plate made of a rectangular parallelepiped formed so as to be arranged on the incident side surface according to the above light guide plate, and from the point light source For example, it is possible to convert incident light into a linear light source. In that case, in the system in which the point light source is arranged on the side surface of the linear light guide plate, an optical path changing means having an appropriate form including a dot structure or a repetitive structure of prismatic unevenness can be provided on the back surface of the linear light guide plate. .

面光源装置の形成に際しては図4,5の例の如く、光源からの放射光を導光板の入射側面に効率よく導くために光源21を包囲する光源ホルダ22などの適宜な補助手段を配置することもできる。光源ホルダは、高反射率の金属薄膜を付設した樹脂シートや金属箔、白色シートなどが一般に用いられる。またバックライトとして用いる場合、光源ホルダを導光板の光出射面に延設して反射シートを兼ねさすこともできる。   When forming the surface light source device, as shown in FIGS. 4 and 5, appropriate auxiliary means such as a light source holder 22 that surrounds the light source 21 is disposed to efficiently guide the emitted light from the light source to the incident side surface of the light guide plate. You can also As the light source holder, a resin sheet, a metal foil, a white sheet or the like provided with a highly reflective metal thin film is generally used. Moreover, when using as a backlight, a light source holder can be extended to the light-projection surface of a light-guide plate, and can also serve as a reflective sheet.

本発明の液晶表示装置用の面光源装置は、光源からの光を効率よく利用して明るさに優れる面光源を提供し、大面積化等も容易であることより反射型液晶表示装置のフロントライトシステムや透過型液晶表示装置の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。 The surface light source device for a liquid crystal display device of the present invention provides a surface light source excellent in brightness by efficiently using light from the light source, and is easy to increase in area and the like. The present invention can be preferably applied to various devices as a light system or a backlight system of a transmissive liquid crystal display device.

図4に面光源装置をフロントライトシステムに用いた本発明の反射型液晶表示装置を例示した。これは面光源装置2における上面11に光出射手段を有する導光板1の光出射面(下面12)側に液晶セル32の表裏に偏光板31、33を有し、かつ裏面に反射層34を具備する反射型の液晶表示ユニット3を配置して形成したものであり、面光源装置を消灯して外光による反射型液晶表示装置としても用いうるものである。 FIG. 4 illustrates a reflective liquid crystal display device of the present invention in which a surface light source device is used in a front light system. This has polarizing plates 31 and 33 on the front and back of the liquid crystal cell 32 on the light emitting surface (lower surface 12) side of the light guide plate 1 having the light emitting means on the upper surface 11 in the surface light source device 2, and the reflective layer 34 on the rear surface. The reflection type liquid crystal display unit 3 provided is formed and can be used as a reflection type liquid crystal display device using external light by turning off the surface light source device.

一方、図5に、参考例として、面光源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。これは面光源装置2における導光板1の上側に光拡散層4を介して透過型の液晶表示ユニット3を配置して形成したものであり、導光板1がその光出射面に反射層5を有して透過型に加え、反射・透過両用の液晶表示装置として用いうるものである。 On the other hand, FIG. 5 illustrates a liquid crystal display device using a surface light source device in a backlight system as a reference example . This is formed by disposing a transmissive liquid crystal display unit 3 on the upper side of the light guide plate 1 in the surface light source device 2 via a light diffusion layer 4, and the light guide plate 1 has a reflection layer 5 on its light exit surface. It can be used as a liquid crystal display device for both reflection and transmission in addition to the transmission type.

なお図5の例では、上面11に光出射手段を有する導光板1を用いた面光源装置2における導光板の上面側に透過型の液晶セル32を配置したものを例示したが、光出射手段を下面に形成した導光板についても同様にして用い得る。従って導光板は、光出射手段の形成面と非形成面のいずれの側も液晶セル側として配置でき、その場合に導光板の裏面側、すなわち液晶セルを配置しない側に反射層等の光反射手段を配置することで反射・透過両用の液晶表示装置を形成することができる。   In the example of FIG. 5, the surface light source device 2 using the light guide plate 1 having the light emitting means on the upper surface 11 is illustrated as having the transmissive liquid crystal cell 32 arranged on the upper surface side of the light guide plate. The light guide plate formed on the lower surface can be used in the same manner. Therefore, the light guide plate can be arranged on either the liquid crystal cell side of the light emitting means forming surface or non-forming surface. By arranging the means, a liquid crystal display device for both reflection and transmission can be formed.

前記した図例の如く液晶表示装置は、面光源装置と液晶セルを少なくとも用いて、その液晶セルを面光源装置における導光板1の所定面側に配置することにより形成される。その場合、面光源装置をフロントライトに用いる反射型の液晶表示装置では、図4の如く裏面に反射層34を具備する液晶表示ユニット3の視認側に面光源装置2がその導光板1の光出射手段形成面が上側(視認側)となるように配置される。   As described above, the liquid crystal display device is formed by using at least a surface light source device and a liquid crystal cell and disposing the liquid crystal cell on a predetermined surface side of the light guide plate 1 in the surface light source device. In that case, in the reflection type liquid crystal display device using the surface light source device for the front light, the surface light source device 2 is light of the light guide plate 1 on the viewing side of the liquid crystal display unit 3 having the reflective layer 34 on the back surface as shown in FIG. It arrange | positions so that the output means formation surface may become an upper side (viewing side).

従ってフロントライトシステムによる反射型の液晶表示装置では、面光源装置の導光板と反射層との間に少なくとも液晶セルの液晶層が位置して、導光板の光出射手段形成面が視認側となるように配置することが必須とされる。その視認は、外部より面光源装置の導光板における光出射手段間からなる部分11aを透過した外光又は点灯時の導光板による出射光が液晶セルを透過して反射層で反転し、その反転光が再度液晶セルを透過した後、導光板における当該部分11aを透過することにより行われる。なお前記の反射層は、セル基板に付設するなどして液晶セル内に設けることもできる。   Therefore, in the reflective liquid crystal display device using the front light system, at least the liquid crystal layer of the liquid crystal cell is located between the light guide plate of the surface light source device and the reflective layer, and the light emitting means forming surface of the light guide plate is on the viewing side. It is indispensable to arrange in this way. The visual recognition is that the external light transmitted through the portion 11a formed between the light emitting means in the light guide plate of the surface light source device or the light emitted from the light guide plate at the time of lighting passes through the liquid crystal cell and is inverted by the reflective layer. The light is transmitted again through the liquid crystal cell and then transmitted through the portion 11a of the light guide plate. The reflective layer can be provided in the liquid crystal cell by attaching it to the cell substrate.

一方、図5の如く面光源装置をバックライトに用いる透過型等の液晶表示装置では、液晶セルの裏面(視認背面)側に面光源装置の導光板が配置され、視認側に光出射手段形成面を有する導光板を用いるときや反射・透過両用で用いるときには液晶セルと反射層の間に面光源装置の導光板が配置される。それらの場合、上記したように面光源装置はその導光板の光出射手段形成面側を図例の如く液晶セル側として配置することもできるし、図例とは反対に導光板の光出射手段を有しない光出射面側を液晶セル側として配置することもできる。   On the other hand, in a transmissive liquid crystal display device using a surface light source device as a backlight as shown in FIG. 5, a light guide plate of the surface light source device is disposed on the back surface (viewing back surface) side of the liquid crystal cell, and light emitting means is formed on the viewing side. When using a light guide plate having a surface or for both reflection and transmission, the light guide plate of the surface light source device is disposed between the liquid crystal cell and the reflection layer. In those cases, as described above, the surface light source device can be arranged such that the light emitting means forming surface side of the light guide plate is the liquid crystal cell side as shown in the figure, or the light emitting means of the light guide plate is opposite to the figure example. It is also possible to dispose the light emitting surface side without the liquid crystal cell side.

図例の如く導光板の光出射手段形成面側を液晶セル側として光出射面に配置した反射層を介し反転させる方式は、上記したように光出射手段から液晶セルに入射するまでの光路長を増大させて光出射手段による輝線パターンを緩和でき、図例とは反対に導光板の光出射面側を液晶セル側として配置する方式に比べモアレ等の表示不良の発生を抑制できる利点などがある。   As shown in the figure, the method of reversing through the reflection layer arranged on the light emitting surface with the light emitting means forming surface side of the light guide plate as the liquid crystal cell side is the optical path length from the light emitting means to the liquid crystal cell as described above. In contrast to the example shown in the figure, the bright line pattern by the light emitting means can be relaxed and the occurrence of display defects such as moire can be suppressed compared to the method in which the light emitting surface side of the light guide plate is arranged on the liquid crystal cell side. is there.

前記した透過型液晶表示装置による視認は、面光源装置による出射光が直接又は反射層による反転を介し液晶セルに入射して透過することにより行われる。また反射・透過両用の液晶表示装置による視認は、透過モードでは前記の透過型に準じ、反射モードでは外光が液晶セルを透過して導光板裏面の反射層で反転し、その反転光が再度導光板における光出射手段間からなる部分11aと液晶セルを透過することにより行われる。   Visual recognition by the transmissive liquid crystal display device described above is performed when light emitted from the surface light source device enters the liquid crystal cell directly or through inversion by a reflective layer and is transmitted. Further, the visual recognition by the liquid crystal display device for both reflection and transmission is the same as the transmission type in the transmission mode. In the reflection mode, the external light is transmitted through the liquid crystal cell and inverted by the reflection layer on the back surface of the light guide plate. This is performed by transmitting the portion 11a between the light emitting means in the light guide plate and the liquid crystal cell.

液晶表示装置は一般に、前記図4、図5の如く液晶シャッタとして機能する透明電極具備の液晶セル32とそれに付随の駆動装置や偏光板等からなる液晶表示ユニット、必要に応じ点灯/消灯の切り替えスイッチを組み込んだバックライト又はフロントライト及び必要に応じての光拡散層4や反射層5、反射防止層や補償用位相差板等の構成部品を適宜に組立てることなどにより形成される。   In general, the liquid crystal display device is a liquid crystal cell 32 having a transparent electrode functioning as a liquid crystal shutter as shown in FIGS. 4 and 5, a liquid crystal display unit including a driving device and a polarizing plate attached thereto, and switching on / off as necessary. It is formed by appropriately assembling components such as a backlight or a front light incorporating a switch and, if necessary, a light diffusion layer 4 or a reflection layer 5, an antireflection layer or a compensation retardation plate.

本発明においては上記した導光板ないし面光源装置を用いる点を除いて特に限定はなく、図例の如く従来に準じて形成することができる。従って用いる液晶セルについては特に限定はなく、例えば液晶の配向形態に基づく場合、TN液晶セルやSTN液晶セル、垂直配向セルやHANセル、OCBセルの如きツイスト系や非ツイスト系、ゲストホスト系や強誘電性液晶系の液晶セルなどの適宜なものを用いうる。また液晶の駆動方式についても特に限定はなく、例えばアクティブマトリクス方式やパッシブマトリクス方式などの適宜な駆動方式であってよい。   In the present invention, there is no particular limitation except that the above-described light guide plate or surface light source device is used. Accordingly, the liquid crystal cell to be used is not particularly limited. For example, when the liquid crystal cell is based on the alignment form of the liquid crystal, a twist type or non-twist type such as a TN liquid crystal cell, an STN liquid crystal cell, a vertical alignment cell, a HAN cell, or an OCB cell, a guest host type, An appropriate liquid crystal cell such as a ferroelectric liquid crystal cell can be used. Also, there is no particular limitation on the liquid crystal driving method, and an appropriate driving method such as an active matrix method or a passive matrix method may be used.

なお図4、図5において液晶セル32は、セル基板の間に液晶層を封入してなるがその場合、セル基板に導光板を兼ねさすこともできる。また図例では、透明電極とそれに付随の駆動装置の記入を省略している。 4 and 5, the liquid crystal cell 32 is formed by sealing a liquid crystal layer between the cell substrates. In this case, the cell substrate can also serve as a light guide plate . In the example of the figure, the transparent electrode and the accompanying driving device are not shown.

液晶セル表裏の一方又は両方に設ける偏光板についても特に限定はないが、高度な直線偏光の入射による良好なコントラスト比の表示を得る点などより、特にバックライト側やフロントライト側の偏光板として、例えばヨウ素系や染料系の吸収型直線偏光子などの如く偏光度の高いものを用いることが好ましい。   There is no particular limitation on the polarizing plate provided on one or both of the front and back of the liquid crystal cell. However, as a polarizing plate on the backlight side or the front light side, in particular, from the point of obtaining a good contrast ratio display by incidence of highly linear polarized light. For example, it is preferable to use a material having a high degree of polarization such as an iodine type or dye type absorption linear polarizer.

反射層についも、例えばアルミニウムや銀、金や銅やクロム等の高反射率金属の粉末をバインダ樹脂中に含有する塗工層や蒸着方式等による金属薄膜の付設層、その塗工層や付設層を基材で支持した反射シート、金属箔などの従来に準じた適宜な反射層として形成することができる。液晶セルの内部に反射層を設ける場合、その反射層としては前記の高反射率金属等の高導電性材料にて電極パターンを形成する方式や、高反射率金属膜で形成した反射層の上に絶縁層を介して透明電極パターンを設ける方式などによる反射層が好ましい。 Even with the reflective layer, such as aluminum or silver, attached layer of thin metal film of the coating layer, vapor deposition method in which a powder of a highly reflective metal gold or copper or chromium contained in the binder resin, Ya the coating layer It can be formed as an appropriate reflective layer according to the prior art, such as a reflective sheet or a metal foil in which the attachment layer is supported by a base material. When a reflective layer is provided inside the liquid crystal cell, the reflective layer may be a method of forming an electrode pattern with a highly conductive material such as the above-described highly reflective metal or a reflective layer formed of a highly reflective metal film. A reflective layer by a method of providing a transparent electrode pattern through an insulating layer is preferable.

なお反射型液晶表示装置における反射層は、例えばプラスチックフィルム上に高反射率金属膜からなる反射層を設けたものなどとして液晶セルの外側に設けることもできる。また透過型液晶表示装置の場合には、そのバックライトを形成する導光板に直接付設することもできる。その反射層は、上記に例示の適宜な方式で導光板の利用形態に応じ導光板の光出射手段形成面又は光出射面のいずれにも設けることができる。   The reflective layer in the reflective liquid crystal display device can also be provided outside the liquid crystal cell, for example, as a reflective layer made of a highly reflective metal film on a plastic film. In the case of a transmissive liquid crystal display device, it can be directly attached to a light guide plate forming the backlight. The reflection layer can be provided on either the light emitting means forming surface or the light emitting surface of the light guide plate in accordance with the use form of the light guide plate in an appropriate manner exemplified above.

液晶表示装置の形成に際しては、上記の如く例えば視認側の表面に設けるアンチグレア層や反射防止膜、あるい光拡散板や補償用位相差板、偏光分離板や光路制御等を目的としたプリズムシートなどの適宜な光学素子を適宜な位置に配置することができる。なお反射防止膜は、導光板の光出射面などにも設けることができる。   When forming a liquid crystal display device, as described above, for example, an antiglare layer or an antireflection film provided on the surface on the viewing side, a light diffusion plate, a compensation phase difference plate, a polarization separation plate, a prism sheet for the purpose of optical path control, etc. An appropriate optical element such as can be arranged at an appropriate position. The antireflection film can also be provided on the light exit surface of the light guide plate.

前記の補償用位相差板は、複屈折の波長依存性などを補償して視認性の向上等をはかることを目的とするものであり、視認側又は/及びバックライト側の偏光板と液晶セルの間等に必要に応じて配置される。補償用位相差板としては、波長域などに応じて適宜なものを用いることができる。その位相差板は、例えばポリカーボネートやポリスルホン、ポリエステルやポリメチルメタクリレート、ポリアミドやポリビニールアルコール等からなるフィルムを延伸処理してなる複屈折性シートや液晶ポリマー配向層の支持シートなどとして得ることができ、それら位相差シートを2層以上重畳したものなどとして形成することもできる。   The compensation phase difference plate is intended to improve the visibility by compensating the wavelength dependence of birefringence, and the polarizing plate and the liquid crystal cell on the viewing side or / and the backlight side It arrange | positions as needed between. As the compensation phase difference plate, an appropriate one can be used according to the wavelength region or the like. The retardation plate can be obtained, for example, as a birefringent sheet obtained by stretching a film made of polycarbonate, polysulfone, polyester, polymethyl methacrylate, polyamide, polyvinyl alcohol, or the like, or a support sheet for a liquid crystal polymer alignment layer. These retardation sheets can be formed as a laminate of two or more layers.

また光拡散層は、明暗ムラの防止による明るさの均等な面発光を得るためや隣接光線の混交によるモアレの低減などを目的に、必要に応じて液晶表示装置の適宜な位置に1層又は2層以上配置するものである。ちなみに図5の例では、導光板1と液晶表示ユニット3の間に光拡散層4が配置されている。なお導光板出射光の指向性の維持などの点よりは、拡散範囲の狭い拡散層が好ましく用いうる。   In addition, the light diffusing layer is formed as a single layer or an appropriate layer on the liquid crystal display device as necessary for the purpose of obtaining surface light emission with uniform brightness by preventing unevenness of light and dark or reducing moire by mixing adjacent light beams. Two or more layers are arranged. Incidentally, in the example of FIG. 5, the light diffusion layer 4 is disposed between the light guide plate 1 and the liquid crystal display unit 3. Note that a diffusion layer having a narrow diffusion range can be preferably used from the viewpoint of maintaining the directivity of the light emitted from the light guide plate.

光拡散層は、上記した光出射面の微細凹凸に準じて、例えば低屈折率の透明樹脂中に高屈折率の透明粒子を分散させて塗布硬化させる方式や気泡を分散させた透明樹脂を塗布硬化させる方式、基材表面を溶媒を介し膨潤させてクレイズを発生させる方式や不規則な凹凸面を有する透明樹脂層を形成する方式、あるいは前記に準じて形成した拡散シートを用いる方式などの適宜な方式で形成することができる。   The light diffusing layer is coated with, for example, a method of dispersing and curing high refractive index transparent particles in a low refractive index transparent resin or a transparent resin in which bubbles are dispersed in accordance with the fine unevenness of the light exit surface described above. Appropriate methods such as a method of curing, a method of generating a craze by swelling the surface of a substrate through a solvent, a method of forming a transparent resin layer having irregular irregular surfaces, or a method of using a diffusion sheet formed according to the above It can be formed by any method.

なお透過型液晶表示装置の形成に際しては、輝度の向上を目的に面光源装置と偏光板の間に偏光分離板を配置することもできる。偏光分離板は、例えば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、透明基板上に誘電体の多層膜を設けたものなどの如く、自然光を透過と反射を介して偏光に分離する機能を有するものである。ちなみに、コレステリック液晶相によれば透過と反射を介して左右の円偏光に分離でき、前記誘電体の多層膜によれば透過と反射を介してP波とS波の直線偏光に分離することができる。また円偏光は、1/4波長板を介して直線偏光に変換することができる。   In forming a transmissive liquid crystal display device, a polarization separation plate can be disposed between the surface light source device and the polarizing plate for the purpose of improving luminance. The polarization separation plate transmits natural light, such as a layer having a cholesteric liquid crystal phase, a sheet having a layer made of a liquid crystal polymer exhibiting a cholesteric phase, or a dielectric multilayer film on a transparent substrate. It has a function of separating into polarized light through reflection. Incidentally, the cholesteric liquid crystal phase can be separated into left and right circularly polarized light through transmission and reflection, and the dielectric multilayer film can be separated into P wave and S wave linearly polarized light through transmission and reflection. it can. Circularly polarized light can be converted to linearly polarized light through a quarter-wave plate.

そのため偏光分離板を透過した偏光を偏光軸を可及的に一致させて偏光板に入射させることにより、偏光板による吸収ロスを抑制できて輝度の向上を図りうる。また図5の如く裏面に反射層5を設けた導光板1からなる面光源装置では、前記の偏光分離板で反射された偏光を反射層5で反転させて偏光分離板に再入射させることにより反転光の一部又は全部を透過させることができ、その光利用効率の向上により輝度の向上を図りうる。   Therefore, by causing the polarized light that has passed through the polarization separator plate to be incident on the polarizing plate with the polarization axis being matched as much as possible, the absorption loss due to the polarizing plate can be suppressed and the luminance can be improved. Further, in the surface light source device composed of the light guide plate 1 provided with the reflection layer 5 on the back surface as shown in FIG. 5, the polarized light reflected by the polarization separation plate is inverted by the reflection layer 5 and re-entered on the polarization separation plate. A part or all of the inverted light can be transmitted, and the luminance can be improved by improving the light utilization efficiency.

本発明において、上記した面光源装置や液晶表示装置を形成する導光板や液晶セルや偏光板等の光学素子ないし部品は、全体的又は部分的に積層一体化されて固着されていてもよいし、分離容易な状態に配置されていてもよい。界面反射の抑制によるコントラストの低下防止などの点よりは、固着状態にあることが好ましい。その固着密着処理には、粘着剤等の適宜な透明接着剤を用いることができる。   In the present invention, the optical elements or components such as the light guide plate, the liquid crystal cell, and the polarizing plate forming the surface light source device or the liquid crystal display device may be laminated or integrated in whole or in part. , May be arranged in an easily separated state. It is preferable to be in a fixed state from the viewpoint of preventing a decrease in contrast due to suppression of interface reflection. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used for the fixing and adhesion treatment.

実施例1
ポリメチルメタクリレートからなる長方形の同厚平板の上面をダイヤモンドバイトで切削することにより、左右方向及び前後方向に光出射手段を各入射側面に平行に形成して導光板を得た。この導光板は、左右方向38mm、前後方向25mm、肉厚1mmであり左右及び前後方向の入射側面に突出長3mmの透明部分を有し、左右方向の入射側面が前後方向の前側に位置し、前後方向の入射側面が左右方向の右側に位置するものからなる。
Example 1
A light guide plate was obtained by cutting the upper surface of a rectangular plate having the same thickness made of polymethyl methacrylate with a diamond cutting tool so that light emitting means were formed in parallel in the left-right direction and the front-rear direction on each incident side surface. This light guide plate is 38 mm in the left-right direction, 25 mm in the front-rear direction, 1 mm in thickness, has a transparent portion with a projection length of 3 mm on the incident side surface in the left-right and front-rear directions, and the incident side surface in the left-right direction is located on the front side in the front-rear direction. The incident side surface in the front-rear direction is located on the right side in the left-right direction.

また前記した左右方向の光出射手段は、260μmの一定ピッチによるプリズム状凹凸の繰返し構造よりなり、入射側面に対面する伝送光反射面の傾斜角が43度で、その対向面の傾斜角が62度であり、伝送光反射面の下面に対する投影幅が10〜16μmで、プリズム状凹凸のピッチ間における上面部分/プリズム状凹凸の下面に対する投影幅比が10倍以上のものからなる。   The light emitting means in the left-right direction has a repetitive structure of prism-like irregularities with a constant pitch of 260 μm, the transmission light reflecting surface facing the incident side has an inclination angle of 43 degrees, and the opposite surface has an inclination angle of 62. The projection width on the lower surface of the transmission light reflecting surface is 10 to 16 μm, and the projection width ratio between the upper surface portion / the lower surface of the prismatic unevenness between the pitches of the prismatic unevenness is 10 times or more.

また前後方向の光出射手段は、310μmの一定ピッチによるプリズム状凹凸の繰返し構造よりなり、入射側面に対面する伝送光反射面の傾斜角が43度で、その対向面の傾斜角が62度であり、伝送光反射面の下面に対する投影幅が9〜16μmで、プリズム状凹凸のピッチ間における上面部分/プリズム状凹凸の下面に対する投影幅比が12倍以上のものからなる。   Further, the light emitting means in the front-rear direction has a repetitive structure of prismatic irregularities with a constant pitch of 310 μm, the transmission light reflecting surface facing the incident side has an inclination angle of 43 degrees, and the opposite surface has an inclination angle of 62 degrees. The projection width of the transmission light reflecting surface on the lower surface is 9 to 16 μm, and the projection width ratio between the upper surface portion and the lower surface of the prismatic unevenness between the pitches of the prismatic unevenness is 12 times or more.

次に前記の導光板における左右方向の入射側面に幅42mm、奥行2.5mm、厚さ1.5mmの直方体からなる有効発光幅41mmの線状導光板の左右両面に緑色と赤色の発光ダイオードを1個ずつ設けて色別に直流電源と接続した光源1を配置し、前後方向の入射側面に幅29mm、奥行2.5mm、厚さ1.5mmの直方体からなる有効発光幅28mmの線状導光板の前後両面に赤色発光ダイオードを1個ずつ設けて直流電源と接続した光源2を配置して面光源装置を得た。   Next, green and red light emitting diodes are formed on both the left and right sides of a linear light guide plate having an effective light emission width of 41 mm made of a rectangular parallelepiped having a width of 42 mm, a depth of 2.5 mm, and a thickness of 1.5 mm on the incident side surface in the left-right direction of the light guide plate. A linear light guide plate having an effective light emission width of 28 mm, which is a rectangular parallelepiped having a width of 29 mm, a depth of 2.5 mm, and a thickness of 1.5 mm on the incident side surface in the front-rear direction, arranged one by one and connected to a DC power supply for each color. A surface light source device was obtained by disposing one light emitting diode on each of the front and rear surfaces of the light source 2 and connecting the light source 2 connected to a DC power source.

ついで前記の面光源装置における導光板の下面側に反射型のツイストネマチック系液晶表示ユニットを配置して、フロントライト式の反射型液晶表示装置を得た。なお視認は、光出射手段を形成した導光板の上面側を介して行われる。   Then, a reflective twisted nematic liquid crystal display unit was disposed on the lower surface side of the light guide plate in the surface light source device to obtain a front light type reflective liquid crystal display device. The visual recognition is performed via the upper surface side of the light guide plate on which the light emitting means is formed.

実施例2
左右方向の光出射手段を左右方向の入射側面に対してそのプリズム状凹凸の稜線が右上がりに14度の傾斜角となるように形成し、前後方向の光出射手段を前後方向の入射側面に対してそのプリズム状凹凸の稜線が14度の傾斜角で前側に上がるように形成したほかは実施例1に準じて導光板と面光源装置と反射型液晶表示装置を得た。
Example 2
The light emitting means in the left-right direction is formed so that the ridge line of the prism-shaped unevenness with respect to the incident side surface in the left-right direction has an inclination angle of 14 degrees to the right, and the light emitting means in the front-rear direction is formed on the incident side surface in the front-rear direction. On the other hand, a light guide plate, a surface light source device, and a reflective liquid crystal display device were obtained in the same manner as in Example 1 except that the ridge line of the prism-shaped unevenness was formed so as to rise forward with an inclination angle of 14 degrees.

なお前記光出射手段の傾斜化の結果、左右方向の光出射手段ではその伝送光反射面の下面に対する投影幅が10〜18μmに変化し、プリズム状凹凸のピッチ間における上面部分/プリズム状凹凸の下面に対する投影幅比が8倍以上に変化した。また前後方向の光出射手段では、伝送光反射面の下面に対する投影幅が9〜18μmに変化し、プリズム状凹凸のピッチ間における上面部分/プリズム状凹凸の下面に対する投影幅比が10倍以上に変化した。   As a result of the inclination of the light emitting means, the projection width of the light emitting means in the left-right direction to the lower surface of the transmission light reflecting surface changes to 10 to 18 μm, and the upper surface portion / prism-shaped unevenness between the pitches of the prismatic unevenness. The projected width ratio with respect to the lower surface changed to 8 times or more. Further, in the light emitting means in the front-rear direction, the projection width on the lower surface of the transmission light reflecting surface changes to 9 to 18 μm, and the projection width ratio on the upper surface portion / prism-shaped uneven surface between the prism-shaped uneven pitches is more than 10 times. changed.

参考例1
実施例2で得た面光源装置をその導光板の上下面を逆転させて配置し、その光出射手段形成面(元上面)の下側に白色ポリエステルフィルムからなる反射板を配置し、かつ光出射面側(元下面側)に拡散板を介して透過型のツイストネマチック系液晶表示ユニットを配置して、バックライト式の透過型液晶表示装置を得た。
Reference example 1
The surface light source device obtained in Example 2 is disposed with the upper and lower surfaces of the light guide plate reversed, a reflector made of a white polyester film is disposed below the light emitting means forming surface (original upper surface), and light A transmissive twisted nematic liquid crystal display unit was disposed on the light exit surface side (original lower surface side) via a diffusion plate to obtain a backlight type transmissive liquid crystal display device.

参考例2
実施例2で得た面光源装置の下面側に銀蒸着の反射板を配置し、かつ上面側に透過型のツイストネマチック系液晶表示ユニットを配置して、バックライト式の透過型液晶表示装置を得た。
Reference example 2
A backlight-type transmissive liquid crystal display device is provided by disposing a silver-deposited reflector on the lower surface side of the surface light source device obtained in Example 2 and a transmissive twisted nematic liquid crystal display unit on the upper surface side. Obtained.

比較例1
傾斜角43度の二等辺三角形からなるプリズム状凹凸を260μmの一定ピッチによる繰返し構造で左右方向の入射側面に平行な光出射手段を形成し、前後方向の光出射手段を省略したほかは実施例1に準じて導光板と面光源装置と反射型液晶表示装置を得た。なお導光板における光出射手段は、その下面に対する投影幅が12μmで、プリズム状凹凸のピッチ間における上面部分/プリズム状凹凸の下面に対する投影幅比が8倍以上であった。
Comparative Example 1
Example except that prism-like irregularities made of isosceles triangles with an inclination angle of 43 degrees are formed in a repeating structure with a constant pitch of 260 μm and light emitting means parallel to the incident side surface in the left-right direction is formed, and the light emitting means in the front-rear direction is omitted. 1 was obtained, a light guide plate, a surface light source device, and a reflective liquid crystal display device were obtained. The light emitting means of the light guide plate had a projection width of 12 μm on its lower surface, and the projection width ratio of the upper surface portion / prism-shaped uneven surface to the lower surface of the prism-shaped unevenness was 8 times or more.

比較例2
比較例1による面光源装置を用いたほかは実施例3に準じて透過型液晶表示装置を得た。
Comparative Example 2
A transmissive liquid crystal display device was obtained according to Example 3 except that the surface light source device according to Comparative Example 1 was used.

比較例3
サンドブラスト加工による粗面を光出射手段として片面に有する導光板を用いたほかは実施例3に準じて面光源装置と透過型液晶表示装置を得た。なお導光板の粗面が下側となるように配置した。
Comparative Example 3
A surface light source device and a transmissive liquid crystal display device were obtained in the same manner as in Example 3 except that a light guide plate having a rough surface by sandblasting on one side as a light emitting means was used. In addition, it arrange | positioned so that the rough surface of a light-guide plate may become a lower side.

比較例4
比較例1による面光源装置を用いたほかは実施例4に準じて透過型液晶表示装置を得た。
Comparative Example 4
A transmissive liquid crystal display device was obtained according to Example 4 except that the surface light source device according to Comparative Example 1 was used.

比較例5
比較例3による面光源装置を用いたほかは実施例4に準じて透過型液晶表示装置を得た。
Comparative Example 5
A transmissive liquid crystal display device was obtained according to Example 4 except that the surface light source device according to Comparative Example 3 was used.

評価試験1
実施例、比較例で得た反射型又は透過型の液晶表示装置について、液晶セルを電圧無印加の状態で光源1又は光源2を点灯させ、装置中央部、点灯側の入射部及びその対向部における正面輝度を輝度計(トプコン社製、BM7)にて調べた。その結果を次表に示した。なお光源1は緑光による。
Evaluation test 1
In the reflective or transmissive liquid crystal display devices obtained in the examples and comparative examples, the light source 1 or the light source 2 is turned on with no voltage applied to the liquid crystal cell, and the central portion of the device, the incident portion on the lighting side, and the opposing portion thereof The front luminance at was measured with a luminance meter (Topcon, BM7). The results are shown in the following table. The light source 1 is green light.

正面輝度(cd/m
光 源 1 光 源 2
入射部 中央部 対向部 入射部 中央部 対向部
実施例1 23 25 26 13 14 14
実施例2 22 24 26 12 12 14
参考例1 39 34 32 19 20 19
参考例2 35 36 34 17 17 15
比較例1 26 22 18 15 11 8
比較例2 45 31 27 22 16 13
比較例3 30 25 22 17 14 10
比較例4 39 32 29 20 16 13
比較例5 25 23 18 12 12 11
Front brightness (cd / m 2 )
Light source 1 light source 2
Incident part Center part Opposing part Incident part Center part Opposing part
Example 1 23 25 26 13 14 14
Example 2 22 24 26 12 12 14
Reference Example 1 39 34 32 19 20 19
Reference Example 2 35 36 34 17 17 15
Comparative Example 1 26 22 18 15 11 8
Comparative Example 2 45 31 27 22 16 13
Comparative Example 3 30 25 22 17 14 10
Comparative Example 4 39 32 29 20 16 13
Comparative Example 5 25 23 18 12 12 11

評価試験2
実施例、比較例で得た反射型又は透過型の液晶表示装置について外観観察を行った結果、実施例では全面にわたり均一で明るい発光状態が得られたが、比較例では入射部で強く発光して対向部に向かい輝度が大きく低下して発光の均一性に劣り、特に比較例3、5の拡散式のものでは実施例に比べ輝度が大きく劣っていた。
Evaluation test 2
As a result of appearance observation of the reflective or transmissive liquid crystal display devices obtained in the examples and comparative examples, a uniform and bright light emission state was obtained over the entire surface in the examples. As a result, the luminance greatly decreased toward the opposite portion and the uniformity of light emission was inferior, and in particular, the diffusion type of Comparative Examples 3 and 5 was greatly inferior in brightness compared to the examples.

また実施例では、光源1による緑と赤の発光色の変換、及び光源の1と2による緑と赤の発光色の変換が可能であり均一で明るい発光状態が得られた。さらに光源の1と2による赤発光では単灯の場合よりも輝度に優れて均一でより明るい発光状態が得られた。しかし比較例では発光ムラで見にくかった。以上より本発明によれば発光色の切り替えが可能で、表示特性に優れるフロントライト式で反射型の液晶表示装置を形成できることわかる。 In the example, green and red emission colors can be converted by the light source 1, and green and red emission colors can be converted by the light sources 1 and 2, and a uniform and bright emission state can be obtained. Further, the red light emission by the light sources 1 and 2 was superior in brightness to a uniform and brighter light emission state than in the case of a single lamp. However, in the comparative example, it was difficult to see due to uneven light emission. Can be switched between emission colors according to the present invention from the above, it can be seen that a reflective-type liquid crystal display device in front light type having excellent display characteristics.

導光板例の平面説明図Plane explanatory diagram of light guide plate example 他の導光板例の平面説明図Plane explanatory drawing of another example of light guide plate 導光板における光出射手段例の側面説明図Side explanatory view of an example of light emitting means in the light guide plate フロントライト式の反射型液晶表示装置例の説明図Explanatory drawing of an example of a front light type reflective liquid crystal display device バックライト式の透過型液晶表示装置例の説明図Illustration of an example of a backlight type transmissive liquid crystal display device

符号の説明Explanation of symbols

1:導光板
11:上面(光出射手段形成面)
A、B:光出射手段(A1:伝送光反射面)
12:下面(光出射面) 13a、b:入射側面
15a、b:透明体による突出部
2:面光源装置(21:光源)
3:液晶表示ユニット
31、33:偏光板 32:液晶セル 34:反射層
4:光拡散層 5:反射層
1: Light guide plate 11: Upper surface (light emitting means forming surface)
A, B: Light emitting means (A1: Transmission light reflecting surface)
12: Lower surface (light emission surface) 13a, b: Incident side surface 15a, b: Projection part by transparent body 2: Surface light source device (21: Light source)
3: Liquid crystal display unit 31, 33: Polarizing plate 32: Liquid crystal cell 34: Reflective layer 4: Light diffusion layer 5: Reflective layer

Claims (5)

上面と下面とその上下面間の側面からなる2面の入射側面を少なくとも有する板状体よりなり、その入射側面が板状体の左右方向と前後方向の側面からなると共に、前記上面に各入射側面からの入射光を下面に出射するための光出射手段を有して、その光出射手段が伝送光反射面とその対向面からなり各入射側面に沿う方向の稜線を有するプリズム状凹凸の80μm〜1mmの一定ピッチによる繰返し構造よりなり、前記伝送光反射面が前記下面の基準平面に対し傾斜角30〜45度で入射側面に対面し当該基準平面に対する投影幅が3〜40μmの斜面からなると共に、前記対向面が当該基準平面に対する傾斜角40度以上の斜面よりなる導光板の各入射側面に光源を配置してなる面光源装置における当該導光板の下面側に、反射層具備の液晶セルを有することを特徴とする液晶表示装置Consists upper and lower surfaces and the plate-like body having at least an incident side surface of the two surfaces thereof made of the side surface between the upper and lower surfaces, with the incident side surface is formed of a left-right direction and the longitudinal direction of the side surface of the plate, each incident on the upper surface 80 μm of prismatic irregularities having light emitting means for emitting incident light from the side surface to the lower surface , the light emitting means having a ridge line in the direction along each incident side surface, which consists of a transmission light reflecting surface and its opposing surface The transmission light reflecting surface has an inclined angle of 30 to 45 degrees with respect to the reference plane of the lower surface, and has an inclined surface with a projection width of 3 to 40 μm with respect to the reference plane. together with the the opposing surface lower surface side of the light guide plate in a surface light source device formed by arranging the light source to the respective incident side surface of the Ru light guide plate name than the inclination angle of 40 degrees or more slopes with respect to the reference plane, the liquid crystal of the reflective layer comprises SE The liquid crystal display device characterized by having. 請求項において、各入射側面に対して設けた光出射手段におけるプリズム状凹凸の稜線が40度以上の角度で交差する導光板を用いてなる液晶表示装置2. The liquid crystal display device according to claim 1 , wherein the light guide plate includes a light guide plate in which the ridges of the prismatic unevenness in the light emitting means provided for each incident side surface intersect at an angle of 40 degrees or more. 請求項1又は2において、2面の入射側面が透明体にて突出形成されており、かつ左右方向の入射側面に対して設けた光出射手段におけるプリズム状凹凸の稜線がその左右方向の入射側面を基準に前後方向の入射側面側より他端側に遠離る方向に傾斜すると共に、前後方向の入射側面に対して設けた光出射手段におけるプリズム状凹凸の稜線がその前後方向の入射側面を基準に左右方向の入射側面側より他端側に遠離る方向に傾斜する導光板を用いてなる液晶表示装置3. The incident side surface of the prism-like unevenness in the light emitting means provided on the incident side surface in the left-right direction is formed by projecting the two incident side surfaces with a transparent body according to claim 1 or 2 . With respect to the incident side surface in the front-rear direction, and the ridge line of the prism-shaped unevenness in the light emitting means provided for the incident side surface in the front-rear direction is referred to the incident side surface in the front-rear direction. A liquid crystal display device using a light guide plate that is inclined in a direction away from the incident side surface side in the left-right direction to the other end side. 請求項1から3のいずれか一項において、点灯・消灯を切り替えうる異色発光の光源が配置された面光源装置を用いてなる液晶表示装置4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device uses a surface light source device in which a light source of different color light emission that can be switched on and off is disposed. 請求項1から4のいずれか一項において、光源が点状光源とそれからの入射光を線状光源に変換する線状導光板からなる線状光源である面光源装置を用いてなる液晶表示装置5. The liquid crystal display device according to claim 1, wherein the light source is a surface light source device that is a linear light source including a point light source and a linear light guide plate that converts incident light therefrom into a linear light source. .
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