JP2005347208A - Flat light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat light source device having a light guide plate on which, the light emitted from a plurality of point-like light sources is incident, restraining generation of emission line, enhancing the utilization rate of the light emitted from the point-like light sources incident on the light guide plate. <P>SOLUTION: The light guide plate has a guiding part 18 diffusing an incident light, and a plate-shaped light collection part 21 formed continuous to the guiding part 18 having a reflection part 20 formed on opposite side of an emission face 19. A plurality of prism-shaped protrusion 27 extending in a direction perpendicular to a virtual end face 21a of the light collection part 21 having a vertex angle of 135°to 150° are formed on the emission face 19. The guiding part 18 is formed into a symmetrical shape widening from light incident side toward the light collection part 21, and the angle between both side faces of the guiding part and a face orthogonal to the virtual end face 21a is 15°to 45°. A plurality of V-shaped grooves 22b extending in thickness direction of the light guide plate 14 are formed in the guiding part 18. The vertex angle α of the V-shaped groove is 60°to 90°, and the ratio of the width of an open end M to the pitch P of adjacent V-shaped groove 22b M/P is 0.3 to 0.7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Translated fromJapanese

本発明は、面光源装置に係り、詳しくはＬＥＤ（発光ダイオード）等の点状光源からの出射光を入射して面状に出射する面光源装置に関する。  The present invention relates to a surface light source device, and more particularly to a surface light source device that emits light emitted from a point light source such as an LED (light emitting diode) and emits the light in a planar shape.

液晶表示装置として液晶表示パネル（液晶パネル）の背面（表示面と反対側の面）に面光源装置をバックライトとして配置したものがある。この種の面光源装置として、ＬＥＤが導光板の端面と対向して配置され、導光板の表面（液晶パネルと対向する側の面）から光が面状に出射されるエッジライト方式（サイドライト型）の装置が提案されている。１個又は少ない数のＬＥＤを使用して導光板から光を均一な面状で出射させる方法としては、導光板の採光手段としての拡散ドットと拡散シートで拡散させることによって指向性を緩和し、プリズムシートで集光して必要な輝度を得る方法がある。散乱ドットは、輝度の均一性を図るために、その密度分布を変化させて形成されている。しかし、ＬＥＤは指向性が強いため、輝線、明部、暗部などが生じやすい。  As a liquid crystal display device, there is one in which a surface light source device is disposed as a backlight on the back surface (surface opposite to the display surface) of a liquid crystal display panel (liquid crystal panel). As this type of surface light source device, an LED is disposed so as to face an end face of a light guide plate, and an edge light system (side light) in which light is emitted in a planar shape from the surface of the light guide plate (the surface facing the liquid crystal panel). Type) devices have been proposed. As a method of emitting light from the light guide plate in a uniform plane using one or a small number of LEDs, the directivity is relaxed by diffusing with diffusion dots and a diffusion sheet as the light collecting means of the light guide plate, There is a method for obtaining necessary luminance by condensing light with a prism sheet. The scattering dots are formed by changing the density distribution in order to achieve uniform brightness. However, since LEDs have strong directivity, bright lines, bright parts, dark parts, etc. are likely to occur.

また、ＬＥＤ等の点状光源を使用した場合に、入射面近傍で輝度ムラが発生するのを抑制するため、導光板の点状光源に対向する領域に、出射面から裏面に延びる（導光板の厚さ方向に延びる）複数の溝を設けた面光源装置が提案されている（例えば、特許文献１参照。）。特許文献１に記載の面光源装置は、図９に示すように、導光板６１と、点状光源としてのＬＥＤ６２とを備えている。導光板６１のＬＥＤ６２と対向する端面には、光出射面６３から裏面（光出射面６３と反対側の面）に延びる複数の溝６４が設けられている。溝６４はＬＥＤ６２の中心軸と直交する面に対して傾いた平面又は曲面により形成された一対の斜面６４ａ，６４ｂを曲面６４ｃにより滑らかに接続して形成されている。
特開平１０−２９３２０２号公報（明細書の段落［００２４］〜［００３０］、図１）In addition, when a point light source such as an LED is used, in order to suppress the occurrence of luminance unevenness in the vicinity of the incident surface, the light guide plate extends from the exit surface to the back surface in a region facing the point light source (light guide plate). A surface light source device provided with a plurality of grooves (extending in the thickness direction) has been proposed (see, for example, Patent Document 1). As shown in FIG. 9, the surface light source device described inPatent Document 1 includes alight guide plate 61 and anLED 62 as a point light source. A plurality ofgrooves 64 extending from thelight emitting surface 63 to the back surface (surface opposite to the light emitting surface 63) are provided on the end surface of thelight guide plate 61 facing theLED 62. Thegroove 64 is formed by smoothly connecting a pair of inclined surfaces 64a and 64b formed by a flat surface or a curved surface with respect to a surface orthogonal to the central axis of theLED 62 by acurved surface 64c.
JP-A-10-293202 (paragraphs [0024] to [0030] of FIG. 1, FIG. 1)

ところが、拡散ドットは導光板の出射面からの出射光の集光性を弱くする。また、特許文献１のように、入射面に導光板の厚さ方向に延びる複数の溝を設けることにより、入射面近傍の輝度ムラを低減させることはできる。しかし、面光源として高輝度化を図ろうとすると輝線が発生し易い。  However, the diffusion dots weaken the condensing property of the outgoing light from the outgoing surface of the light guide plate. Further, as inPatent Document 1, by providing a plurality of grooves extending in the thickness direction of the light guide plate on the incident surface, luminance unevenness in the vicinity of the incident surface can be reduced. However, bright lines are likely to occur when the luminance is increased as a surface light source.

本発明は前記の問題に鑑みてなされたものであって、その目的は複数の点状光源から出射された光を入射するとともに、面状に変換して出射する導光板を備えた面光源装置において、輝線の発生を抑制するとともに点状光源から導光板に入射された入射光の利用率を高めることができる面光源装置を提供することにある。  The present invention has been made in view of the above problems, and an object thereof is a surface light source device including a light guide plate that receives light emitted from a plurality of point light sources and converts the light into a planar shape and emits the light. The present invention provides a surface light source device capable of suppressing the generation of bright lines and increasing the utilization rate of incident light incident on a light guide plate from a point light source.

前記の目的を達成するため、請求項１に記載の発明は、複数の点状光源から出射された光を入射するとともに、面状に変換して出射する導光板を備えた面光源装置である。前記導光板は、入射された光を拡散させる導入部と、前記導入部に連続して形成され、前記導入部から導入された光を出射する出射面及び出射面の反対側に形成された反射部を有する板状の採光部とを備えている。前記出射面には前記採光部の導入部側の仮想端面と直交する方向に延びるとともに頂角が１３５度〜１５０度のプリズム状の突条が複数設けられている。前記導入部は、光の入射側から前記採光部側に向かって拡がる対称形状に形成されるとともにその両側面が前記仮想端面と直交する面との成す角度が１５度〜４５度に形成されている。また、前記導入部の前記点状光源と対向する面には、導光板の厚さ方向に延びる複数のＶ溝が形成され、前記Ｖ溝は頂角が６０度〜９０度、開放端の幅Ｍと隣接するＶ溝のピッチＰとの比Ｍ／Ｐが０．３〜０．７に形成されている。ここで、「プリズム状の突条」とは、断面三角形のプリズムだけでなく、断面三角形のプリズムの二つの斜面の基部側が曲面に形成された形状や、断面三角形のプリズムの頂角の部分が曲面に形成された形状あるいは前記二つの斜面全体が曲面で構成されているものも含む。  In order to achieve the above object, the invention according toclaim 1 is a surface light source device including a light guide plate that receives light emitted from a plurality of point light sources and converts the light into a planar shape and emits the light. . The light guide plate is formed continuously with the introduction part for diffusing incident light, the emission surface for emitting the light introduced from the introduction part, and a reflection formed on the opposite side of the emission surface. And a plate-shaped daylighting unit having a part. The exit surface is provided with a plurality of prismatic protrusions extending in a direction orthogonal to the virtual end surface on the introduction portion side of the daylighting portion and having an apex angle of 135 to 150 degrees. The introduction part is formed in a symmetrical shape that spreads from the light incident side toward the daylighting part side, and an angle formed between the side surfaces of the introduction part and a surface orthogonal to the virtual end face is 15 degrees to 45 degrees. Yes. A plurality of V-grooves extending in the thickness direction of the light guide plate are formed on a surface of the introduction portion facing the point light source, and the V-groove has an apex angle of 60 to 90 degrees and an open end width. A ratio M / P between M and the pitch P of the adjacent V groove is formed to be 0.3 to 0.7. Here, the “prism-shaped protrusion” is not only a prism having a triangular section, but also a shape in which the base sides of the two inclined surfaces of the prism having a triangular section are formed in a curved surface, or a vertex angle portion of a prism having a triangular section. It includes a shape formed on a curved surface or one in which the entire two slopes are formed of a curved surface.

この発明では、点状光源から出射され、導光板の端面から入射された光は、導光板内を前記端面と反対側の端面に向かって導波される間に採光面で反射して、出射面に向かってその進行方向が変更される。そして、出射面に設けられたプリズム状の突条を経て出射される。従って、拡散ドットを使用して点状光源から出射された光の指向性を緩和する構成に比較して、出射面からの出射光の集光性が高められる。また、点状光源からの光が、導入部によって拡散されるため、導光板全体に光を導波させることが容易になる。そして、複数の点状光源の間と対応する箇所に暗部ができたり、逆に点状光源の正面に明部ができたりすることが抑制され、導光板から出射される光の点状光源近傍に発生する輝度ムラが低減する。そして、プリズム状の突条の頂角の値及び導入部の形状を前記のように特定することにより、複数の点状光源から出射された光を入射するとともに、面状に変換して出射する導光板を備えた面光源装置において、輝線の発生を抑制するとともに点状光源から導光板に入射された入射光の利用率を高めることができる。  In this invention, the light emitted from the point light source and incident from the end face of the light guide plate is reflected by the light collecting surface while being guided toward the end face opposite to the end face within the light guide plate, and is emitted. The traveling direction is changed toward the surface. And it is radiate | emitted through the prism-shaped protrusion provided in the output surface. Therefore, the condensing property of the emitted light from the exit surface is enhanced as compared with the configuration in which the directivity of the light emitted from the point light source is relaxed using the diffusion dots. Further, since the light from the point light source is diffused by the introducing portion, it is easy to guide the light through the entire light guide plate. And it is suppressed that a dark part is made in a place corresponding to between a plurality of point light sources, and conversely a bright part is made in front of the point light source, and the vicinity of the point light source of light emitted from the light guide plate The luminance unevenness that occurs is reduced. Then, by specifying the value of the apex angle of the prism-shaped protrusion and the shape of the introduction portion as described above, the light emitted from the plurality of point light sources is incident and converted into a planar shape and emitted. In the surface light source device including the light guide plate, generation of bright lines can be suppressed and the utilization rate of incident light incident on the light guide plate from the point light source can be increased.

請求項２に記載の発明は、請求項１に記載の発明において、前記比Ｍ／Ｐは０．５〜０．７に形成されている。この発明では、輝線が目立たずに輝度を高めるのが容易になる。
請求項３に記載の発明は、請求項１又は請求項２に記載の発明において、前記プリズム状の突条は前記採光部と別体に形成されたプリズムシートで構成されている。この発明では、プリズム状の突条を導光板の出射面に直接形成する場合に比較して、導光板を射出成形等で製造するための金型の構造が簡単になり、導光板の製造が容易になる。The invention according toclaim 2 is the invention according toclaim 1, wherein the ratio M / P is formed to be 0.5 to 0.7. According to the present invention, it becomes easy to increase the luminance without making the bright line noticeable.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the prism-shaped protrusion is formed of a prism sheet formed separately from the daylighting unit. In this invention, the structure of the mold for manufacturing the light guide plate by injection molding or the like is simplified as compared with the case where the prismatic protrusions are directly formed on the light exit surface of the light guide plate. It becomes easy.

請求項４に記載の発明は、請求項１又は請求項２に記載の発明において、前記採光部は前記プリズム状の突条が一体に形成されている。この発明では、プリズムシートを用いる必要がないため、面光源装置を構成する部品点数が少なくなって、組立工数を低減できる。  The invention described in claim 4 is the invention described inclaim 1 or 2, wherein the prism-shaped protrusion is integrally formed in the daylighting unit. In this invention, since it is not necessary to use a prism sheet, the number of parts constituting the surface light source device is reduced, and the number of assembling steps can be reduced.

本発明によれば、複数の点状光源から出射された光を入射するとともに、面状に変換して出射する導光板を備えた面光源装置において、輝線の発生を抑制するとともに点状光源から導光板に入射された入射光の利用率を高めることができる。  According to the present invention, in a surface light source device that includes a light guide plate that receives light emitted from a plurality of point light sources, converts the light into a surface shape, and emits the light. The utilization factor of the incident light incident on the light guide plate can be increased.

以下、本発明を液晶表示装置のサイドライト型のバックライトに使用される面光源装置に具体化した一実施形態を図１〜図７に従って説明する。図１（ａ）は導光板と点状光源の関係を示す模式斜視図、（ｂ）は導入部と点状光源の関係を示す模式平面図、（ｃ）は液晶表示装置の模式図、図２（ａ）は導光板の模式平面図、（ｂ）は模式側面図、（ｃ）は採光部の部分模式側面図である。  Hereinafter, an embodiment in which the present invention is embodied in a surface light source device used for a sidelight type backlight of a liquid crystal display device will be described with reference to FIGS. 1A is a schematic perspective view showing the relationship between the light guide plate and the point light source, FIG. 1B is a schematic plan view showing the relationship between the introducing portion and the point light source, and FIG. 1C is a schematic view of the liquid crystal display device. 2 (a) is a schematic plan view of a light guide plate, (b) is a schematic side view, and (c) is a partial schematic side view of a daylighting unit.

図１（ｃ）に示すように、液晶表示装置１１は、液晶パネル１２と、その背面（表示面と反対側の面）側に配置されたバックライトとしての面光源装置１３とを備えている。面光源装置１３は、導光板１４と、導光板１４の一方の（入射側の）端部と対向する位置に配置された複数の点状光源１５とを備えている。点状光源１５としてはＬＥＤ（発光ダイオード）が使用されている。  As shown in FIG. 1C, the liquidcrystal display device 11 includes aliquid crystal panel 12 and a surfacelight source device 13 as a backlight disposed on the back surface (surface opposite to the display surface). . The surfacelight source device 13 includes alight guide plate 14 and a plurality ofpoint light sources 15 arranged at positions facing one end (incident side) of thelight guide plate 14. As thepoint light source 15, an LED (light emitting diode) is used.

面光源装置１３には、導光板１４を挟んで液晶パネル１２と反対側に位置し、導光板１４から漏れた光を導光板１４に戻して出射光として利用するための反射部材（反射シート）１６が設けられている。また、導光板１４と液晶パネル１２との間には、拡散シート１７が配置されている。  The surfacelight source device 13 is located on the opposite side of theliquid crystal panel 12 with thelight guide plate 14 interposed therebetween, and a reflective member (reflective sheet) for returning the light leaking from thelight guide plate 14 to thelight guide plate 14 and using it asoutgoing light 16 is provided. Adiffusion sheet 17 is disposed between thelight guide plate 14 and theliquid crystal panel 12.

次に導光板１４について詳細に説明する。導光板１４は透明性の高い材料、例えばアクリル樹脂で形成されている。図１（ａ），（ｂ）に示すように、導光板１４は、点状光源１５から入射された光を拡散させる導入部１８と、導入部１８に連続して形成され、導入部１８から導入された光を面状に出射する出射面１９及び出射面１９の反対側に形成された反射部２０を有する板状の採光部２１とを備えている。  Next, thelight guide plate 14 will be described in detail. Thelight guide plate 14 is made of a highly transparent material such as an acrylic resin. As shown in FIGS. 1A and 1B, thelight guide plate 14 is formed continuously with theintroduction portion 18 that diffuses the light incident from thepoint light source 15 and theintroduction portion 18. Anemission surface 19 for emitting the introduced light in a planar shape and a plate-shaped daylighting portion 21 having areflection portion 20 formed on the opposite side of theemission surface 19 are provided.

導入部１８は複数（図１（ａ）では４個図示）隣接して形成されている。導入部１８は、入射部２２及び反射部２３を備えている。導入部１８は、光の入射側から導光板１４の採光部２１側に向かって拡がる対称形状に形成されるとともに、入射側端部の幅Ｗ１（図１（ｂ）における左右方向の長さ）が点状光源１５の幅よりも大きく形成されている。入射部２２は、点状光源１５と対向するとともに、導入部１８の幅方向に延びる面２４と平行な平面２２ａと、点状光源１５からの光を拡散させる拡散部としてのＶ溝２２ｂとが交互に等間隔で繰り返すように構成されている。Ｖ溝２２ｂは、開放端の幅Ｍと、Ｖ溝２２ｂのピッチＰとの比Ｍ／Ｐが０．３〜０．７、好ましくは０．５〜０．７で、頂角αが６０度〜９０度の範囲の所定の値となるように形成されている。  A plurality of introduction portions 18 (four shown in FIG. 1A) are formed adjacent to each other. Theintroduction unit 18 includes an incident unit 22 and areflection unit 23. Theintroduction portion 18 is formed in a symmetrical shape that spreads from the light incident side toward thedaylighting portion 21 side of thelight guide plate 14, and the width W1 of the incident side end portion (the length in the left-right direction in FIG. 1B). Is formed larger than the width of the pointlight source 15. The incident portion 22 is opposed to the pointlight source 15, and includes aplane 22 a parallel to thesurface 24 extending in the width direction of theintroduction portion 18, and aV groove 22 b as a diffusion portion that diffuses light from the pointlight source 15. It is configured to repeat alternately at equal intervals. TheV groove 22b has a ratio M / P between the width M of the open end and the pitch P of theV groove 22b of 0.3 to 0.7, preferably 0.5 to 0.7, and the apex angle α is 60 degrees. It is formed to have a predetermined value in a range of ˜90 degrees.

反射部２３は、導入部１８の両側面で構成され、Ｖ溝２２ｂで拡散された光を採光部２１に向けて反射するように形成されている。反射部２３は平面状であり、反射部２３と導入部１８の幅方向に延びる面２４と直交する面とのなす角度γの値が１５度〜４５度の範囲の所定の値となるように形成されている。  Thereflection portion 23 is configured on both side surfaces of theintroduction portion 18 and is formed so as to reflect the light diffused by theV groove 22 b toward thedaylighting portion 21. Thereflection part 23 is planar, and the value of the angle γ formed by thereflection part 23 and thesurface 24 extending in the width direction of theintroduction part 18 and a surface orthogonal to thereflection part 23 is a predetermined value in the range of 15 degrees to 45 degrees. Is formed.

採光部２１はほぼ四角板状に形成され、導入部１８から入射された光を出射する出射面１９と、出射面１９の反対側の裏面に形成された反射部２０とを有する。反射部２０は、採光部２１の導入部１８側の仮想端面２１ａ（図１（ｂ），（ｃ）に図示）に沿って延びるように形成された複数の平行な溝２６により構成されている。なお、図１（ｂ）においては仮想端面２１ａが面２４と一致している。  Thedaylighting unit 21 is formed in a substantially square plate shape, and includes anemission surface 19 that emits light incident from theintroduction unit 18 and areflection unit 20 that is formed on the back surface opposite to theemission surface 19. Thereflection unit 20 includes a plurality ofparallel grooves 26 formed so as to extend along avirtual end surface 21a (illustrated in FIGS. 1B and 1C) on theintroduction unit 18 side of thedaylighting unit 21. . In FIG. 1B, thevirtual end surface 21 a coincides with thesurface 24.

溝２６は、仮想端面２１ａ側から対向面２１ｂ側に向かって上昇傾斜する採光面２６ａと、仮想端面２１ａ側から対向面２１ｂ側に向かって下降傾斜する傾斜面２６ｂとが交互に連なるように設けられている。即ち、各溝２６は仮想端面２１ａと直交する平面による断面形状が鋸歯状となるように隣接して形成されている。各溝２６は同一形状に形成されている。  Thegroove 26 is provided so that adaylighting surface 26a that rises and slopes from thevirtual end surface 21a side toward the opposingsurface 21b side and aninclined surface 26b that slopes down from thevirtual end surface 21a side and faces the opposingsurface 21b side are alternately arranged. It has been. That is, thegrooves 26 are formed adjacent to each other so that a cross-sectional shape by a plane orthogonal to thevirtual end surface 21a is a sawtooth shape. Eachgroove 26 is formed in the same shape.

採光面２６ａは、導入部１８から採光部２１に入射され、採光面２６ａに到達した光を、出射面１９に形成された後記する各突条２７の頂点と接する仮想平面Ｐ１（図１（ａ）に鎖線で図示）に対してほぼ直角に近い角度で出射面１９の方向に全反射させる角度に形成されている。溝２６は、採光面２６ａが仮想平面Ｐ１と平行な平面と成す角度θ１が例えば３５度〜５０度、好ましくは４０度〜４５度の範囲の所定の角度に、傾斜面２６ｂが仮想平面Ｐ１と平行な平面と成す角度θ２が例えば０．３度〜２．５度の範囲の所定の角度に形成されている。  Thedaylighting surface 26 a is incident on thedaylighting unit 21 from theintroduction unit 18, and the light reaching thedaylighting surface 26 a is contacted with the apex of eachprotrusion 27 formed on theexit surface 19, which will be described later (see FIG. 1A ) Is formed at an angle that causes total reflection in the direction of theexit surface 19 at an angle that is substantially perpendicular to the line). In thegroove 26, the angle θ1 formed by thedaylighting surface 26a and a plane parallel to the virtual plane P1 is, for example, a predetermined angle in the range of 35 ° to 50 °, preferably 40 ° to 45 °, and theinclined surface 26b is connected to the virtual plane P1. The angle θ2 formed with the parallel plane is formed at a predetermined angle in a range of 0.3 degrees to 2.5 degrees, for example.

採光部２１は、板厚ｔが仮想端面２１ａ側から対向面２１ｂ側に向かって次第に小さくなるように形成されている。ここでの板厚ｔは、各溝２６の最深部から出射面までの距離（厳密には、突条２７の基端を含む面までの距離）で定義される。そして、この実施形態では板厚ｔは、指数関数的に減少し、次式の関数Ｆにおいて、ｎ＝１．５としたときに図２（ｂ）に示す初期板厚ｔ０等が次式を満たすように設定されている。  Thedaylighting portion 21 is formed so that the plate thickness t gradually decreases from thevirtual end surface 21a side toward the facingsurface 21b side. The plate thickness t here is defined by the distance from the deepest part of eachgroove 26 to the exit surface (strictly, the distance from the surface including the base end of the protrusion 27). In this embodiment, the sheet thickness t decreases exponentially. When n = 1.5 in the function F of the following expression, the initial sheet thickness t0 shown in FIG. It is set to meet.

関数Ｆ：板厚（ｔ）＝ｔ０−（ｔ０−ｔｅ）（Ｌｉ／Ｌ）^ｎ…（１）
但し、ｔ０：初期板厚、ｔｅ：最終板厚、Ｌｉ：仮想端面から溝までの距離、Ｌ：導光板長さである。Function F: plate thickness (t) = t0− (t0−te) (Li / L)ⁿ (1)
Where t0: initial plate thickness, te: final plate thickness, Li: distance from the virtual end face to the groove, and L: light guide plate length.

出射面１９には、プリズム状の突条２７が採光面２６ａの延びる方向と直交する方向に延びるように、即ち仮想端面２１ａと直交する方向に延びるように複数設けられている。各突条２７は長手方向と直交する切断面での断面形状が二等辺三角形状に形成され、かつ高さが同じに形成されている。各突条２７は端面が仮想平面Ｐ１とほぼ垂直になるように形成されている。また、各突条２７は互いに隣接するように形成され、出射面１９は仮想端面２１ａと直交する方向に延びる一対の斜面を有する突条２７が繰り返し形成された構成となっている。突条２７は、頂角Ｋが１３５度〜１５０度の範囲の所定の角度で、ピッチが５０〜３００μｍの範囲の所定の大きさに形成されている。点状光源１５の幅は例えば２．５ｍｍに形成されている。なお、点状光源１５、導入部１８、溝２６及び突条２７等の大きさの比は、図示の都合上実際とは異なっている。また、図示の都合上、図１（ｂ）及び図２では突条２７の図示を省略している。  A plurality of prism-shapedprotrusions 27 are provided on theemission surface 19 so as to extend in a direction orthogonal to the direction in which thedaylighting surface 26a extends, that is, in a direction orthogonal to thevirtual end surface 21a. Eachprotrusion 27 is formed in the shape of an isosceles triangle in the cross section at the cutting plane orthogonal to the longitudinal direction, and is formed in the same height. Eachprotrusion 27 is formed so that the end face is substantially perpendicular to the virtual plane P1. Eachprotrusion 27 is formed so as to be adjacent to each other, and theemission surface 19 has a structure in which protrusions 27 having a pair of inclined surfaces extending in a direction orthogonal to thevirtual end surface 21a are repeatedly formed. Theridges 27 are formed at a predetermined angle in which the apex angle K is in the range of 135 degrees to 150 degrees and the pitch is in the predetermined range of 50 to 300 μm. The width of the pointlight source 15 is, for example, 2.5 mm. In addition, the ratio of the size of the pointlight source 15, theintroduction part 18, thegroove 26, theprotrusion 27, and the like is different from the actual for convenience of illustration. For convenience of illustration, theprotrusion 27 is not shown in FIGS. 1B and 2.

次に前記のように構成された面光源装置１３の作用について説明する。
点状光源１５が点灯されると、点状光源１５から出射した光が導入部１８から導光板１４に入射し、入射した光は導光板１４の出射面１９から液晶パネル１２に向かって出射され、拡散シート１７を経て液晶パネル１２に入射される。そして、液晶表示装置１１の使用者は液晶パネル１２の表示をその出射光により視認する。Next, the operation of the surfacelight source device 13 configured as described above will be described.
When the pointlight source 15 is turned on, the light emitted from the pointlight source 15 enters thelight guide plate 14 from theintroduction portion 18, and the incident light is emitted from thelight exit surface 19 of thelight guide plate 14 toward theliquid crystal panel 12. Then, the light enters theliquid crystal panel 12 through thediffusion sheet 17. The user of the liquidcrystal display device 11 visually recognizes the display on theliquid crystal panel 12 by the emitted light.

導光板１４における作用を詳しく説明すると、点状光源１５から出射した光の大部分は入射部２２に到達する。入射部２２に到達した光のうち一部は、導入部１８の幅方向に延びる面２４と平行な平面２２ａから導入部１８に入射される。導入部１８の幅方向に延びる面２４と平行な平面２２ａから導入部１８に入射された光の多くは、平面２２ａにおいてその進行方向が平面２２ａと垂直な方向に近づくように屈折し、採光部２１に入射する。  The operation of thelight guide plate 14 will be described in detail. Most of the light emitted from the pointlight source 15 reaches the incident portion 22. A part of the light reaching the incident part 22 is incident on theintroduction part 18 from aplane 22 a parallel to thesurface 24 extending in the width direction of theintroduction part 18. Most of the light incident on theintroduction unit 18 from theplane 22a parallel to thesurface 24 extending in the width direction of theintroduction unit 18 is refracted so that the traveling direction of theplane 22a approaches a direction perpendicular to the plane 22a. 21 is incident.

一方、入射部２２に到達した光のうち残りの一部は、Ｖ溝２２ｂによって、反射部２３に向けて屈折されて導入部１８に入射される。そして、反射部２３において、その多くは採光部２１の幅方向と垂直な方向に近づくように反射され、反射された光は採光部２１に入射する。採光部２１に入射された光は採光部２１内を導波する。そのうち、採光面２６ａに到達した光は、図２（ｃ）に示すように、出射面１９の方向に全反射し、出射面１９から出射する。  On the other hand, the remaining part of the light reaching the incident part 22 is refracted toward thereflection part 23 by theV groove 22b and is incident on theintroduction part 18. In thereflection unit 23, most of the light is reflected so as to approach a direction perpendicular to the width direction of thedaylighting unit 21, and the reflected light enters thedaylighting unit 21. The light incident on thedaylighting unit 21 is guided in thedaylighting unit 21. Of these, the light that has reached thedaylighting surface 26 a is totally reflected in the direction of theexit surface 19 and exits from theexit surface 19 as shown in FIG.

仮想端面２１ａから採光部２１内に入射した光が全て採光面２６ａに向かって直進するとは限らず、採光面２６ａに到達する光には、傾斜面２６ｂや出射面１９で全反射しながら採光部２１内を導波した後、採光面２６ａに到達する光もある。傾斜面２６ｂが仮想端面２１ａ側から対向面２１ｂ側に向かって下降傾斜するように形成されている。そのため、直接採光面２６ａに向かって導波する以外の光が導波を繰り返すうちに、仮想平面Ｐ１と平行な方向に近づき、結果として採光面２６ａで効率良く、出射面１９の方向に全反射させることができる。  The light that has entered thedaylighting unit 21 from thevirtual end surface 21 a does not always travel straight toward thedaylighting surface 26 a, and the light that reaches thedaylighting surface 26 a is totally reflected by theinclined surface 26 b or theexit surface 19, and the daylighting unit There is also light that reaches thedaylighting surface 26 a after being guided through the light 21. Theinclined surface 26b is formed so as to be inclined downward from thevirtual end surface 21a side toward the opposingsurface 21b side. Therefore, as light other than being guided directly toward thedaylighting surface 26a is repeatedly guided, the light approaches the direction parallel to the virtual plane P1, and as a result, is efficiently reflected by thedaylighting surface 26a and totally reflected in the direction of theexit surface 19. Can be made.

点状光源１５から正面に向かって出射された光と、点状光源１５から採光面２６ａに対して斜めに出射された光とを比較すると、後者の方が採光面２６ａで全反射して突条２７内に進んだ後、突条２７の表面から液晶パネル１２に向かって出射される割合が大きい。これは、次の理由による。  Comparing the light emitted from the pointlight source 15 toward the front and the light emitted obliquely from the pointlight source 15 with respect to thelighting surface 26a, the latter is totally reflected by thelighting surface 26a and protrudes. After proceeding into thestripe 27, the ratio of light emitted from the surface of theprotrusion 27 toward theliquid crystal panel 12 is large. This is due to the following reason.

点状光源１５から正面に出射された光は、採光面２６ａで仮想平面Ｐ１に略垂直に反射され、点状光源１５から斜めに出射された光は、採光面２６ａで仮想平面Ｐ１に対して斜めに反射される。前者の光は、突条２７の斜面の法線とのなす角が大きいため、突条２７で反射され、内部に導波するものの割合が大きい。後者の光は、突条２７の斜面の法線とのなす角が小さいため、突条２７から外部に出射されるものの割合が大きい。そして、突条２７から外部に出射されるとき、突条２７の斜面における屈折により、後者の光の進行方向は仮想平面Ｐ１と垂直な方向に近づく。  The light emitted to the front from the pointlight source 15 is reflected substantially perpendicularly to the virtual plane P1 by thelighting surface 26a, and the light emitted obliquely from the pointlight source 15 to the virtual plane P1 by thelighting surface 26a. Reflected diagonally. Since the former light has a large angle with the normal of the slope of theridge 27, the ratio of the light reflected by theridge 27 and guided to the inside is large. Since the latter light has a small angle with the normal of the slope of theridge 27, the ratio of the light emitted from theridge 27 to the outside is large. And when it radiates | emits outside from theprotrusion 27, the advancing direction of the latter light approaches the direction perpendicular | vertical to the virtual plane P1 by the refraction in the slope of theprotrusion 27.

このため、点状光源１５から斜めの方向では、突条２７が存在する場合には、出射面１９の正面に出射する光の割合が大きくなり、突条２７が存在しない場合には、出射面１９の正面に出射する光の割合が小さくなる。反対に、点状光源１５の正面方向では、突条２７が存在する場合には、出射面１９の正面に出射する光の割合が小さくなり、突条２７が存在しない場合には、出射面１９の正面に出射する光の割合が大きくなる。  For this reason, in the oblique direction from the pointlight source 15, when theprotrusion 27 is present, the ratio of the light emitted to the front surface of theemission surface 19 is increased, and when theprotrusion 27 is not present, the emission surface is provided. The ratio of the light emitted to the front of 19 is reduced. On the contrary, in the front direction of the pointlight source 15, when theprotrusion 27 is present, the ratio of the light emitted to the front surface of theemission surface 19 decreases, and when theprotrusion 27 does not exist, theemission surface 19. The ratio of the light emitted to the front of is increased.

そのため、点状光源１５の指向性と関連して、突条２７の頂角Ｋ、Ｖ溝２２ｂの頂角α、反射部２３の角度γの値やＶ溝２２ｂの開放端の幅Ｍと、Ｖ溝２２ｂのピッチＰとの比Ｍ／Ｐが出射面１９から出射される光の輝度や輝度ムラに大きく影響する。また、反射部２０の形状も前記輝度や輝度ムラに影響を与える。  Therefore, in relation to the directivity of the pointlight source 15, the value of the apex angle K of theridge 27, the apex angle α of theV groove 22b, the angle γ of the reflectingportion 23, and the width M of the open end of theV groove 22b, The ratio M / P with the pitch P of the V-groove 22b greatly affects the luminance and luminance unevenness of the light emitted from theemission surface 19. Further, the shape of the reflectingportion 20 also affects the luminance and luminance unevenness.

本願発明者らは、光学シミュレーションにより、突条２７の頂角Ｋ、Ｖ溝２２ｂの頂角α、反射部２３の角度γ、Ｖ溝２２ｂの幅ＭとピッチＰとの比Ｍ／Ｐが前記特定の組合せの場合に、面光源装置１３において、輝線の発生を抑制するとともに点状光源１５から導光板１４に入射された入射光の利用率を高めることを見いだした。  The inventors of the present application determined by optical simulation that the ratio M / P of the apex angle K of theridge 27, the apex angle α of theV groove 22b, the angle γ of the reflectingportion 23, the width M of theV groove 22b and the pitch P is In the case of a specific combination, the surfacelight source device 13 was found to suppress generation of bright lines and increase the utilization rate of incident light incident on thelight guide plate 14 from the pointlight source 15.

シミュレーションは図２（ａ），（ｂ）に示すように、４個の点状光源１５を備え、出射面１９と反対側の面に鋸歯状の溝２６を備えた導光板１４において、輝線輝度比及び中心輝度に対する、突条２７の頂角Ｋ、Ｖ溝２２ｂの頂角α、反射部２３の角度γ、Ｖ溝２２ｂの幅ＭとピッチＰとの比Ｍ／Ｐを変更して行った。結果を表１〜表４及び図４〜図７に示す。  In the simulation, as shown in FIGS. 2A and 2B, the brightness of the emission line is obtained in thelight guide plate 14 having four pointlight sources 15 and having asawtooth groove 26 on the surface opposite to theemission surface 19. The ratio M / P of the apex angle K of theridge 27, the apex angle α of theV groove 22b, the angle γ of the reflectingportion 23, and the width M and pitch P of theV groove 22b with respect to the ratio and the center luminance was changed. . The results are shown in Tables 1 to 4 and FIGS.

なお、図２（ａ）〜（ｃ）及び図１（ｂ）に示す導光板１４及び点状光源１５の各部の値を次のように設定した。
導光板長さ：Ｌ＝５６ｍｍ、導光板幅：Ｗ＝５６ｍｍ、導入部の長さ：Ｌ２＝５．６ｍｍ、導入部の基端幅：Ｗ２＝１４ｍｍ、突条のピッチ＝２５０μｍ、導光板の初期板厚：ｔ０＝０．９６ｍｍ、導光板の最終板厚：ｔｅ＝０．４ｍｍ、点状光源の幅＝２．５ｍｍ、点状光源の長さ＝１．０ｍｍ、鋸歯長さ：Ｌ３＝０．２４ｍｍ、採光面の角度：θ１＝４３度、傾斜面の角度：θ２＝０．７度。In addition, the value of each part of the light-guide plate 14 shown in FIG. 2 (a)-(c) and FIG.1 (b) and the pointlight source 15 was set as follows.
Light guide plate length: L = 56 mm, light guide plate width: W = 56 mm, introduction portion length: L2 = 5.6 mm, introduction portion base end width: W2 = 14 mm, protrusion pitch = 250 μm, light guide plate length Initial plate thickness: t0 = 0.96 mm, final light guide plate thickness: te = 0.4 mm, point light source width = 2.5 mm, point light source length = 1.0 mm, sawtooth length: L3 = 0.24 mm, angle of the lighting surface: θ1 = 43 degrees, angle of the inclined surface: θ2 = 0.7 degrees.

表１はＶ溝２２ｂの頂角αを６０度に設定し、突条２７（縦プリズム）の頂角Ｋ、反射部２３の角度γ、Ｖ溝２２ｂの開放端の幅ＭのピッチＰに対する割合を％として表したβ（＝（Ｍ／Ｐ）×１００）を変更した場合の輝線輝度比の値を示し、図４（ａ），（ｂ），（ｃ）はそれらをグラフに表したものである。表２は同じく中心輝度の値を示し、図５（ａ），（ｂ），（ｃ）はそれらをグラフに表したものである。

Table 1 shows that the apex angle α of theV groove 22b is set to 60 degrees, the apex angle K of the protrusion 27 (vertical prism), the angle γ of the reflectingportion 23, and the ratio of the width M of the open end of theV groove 22b to the pitch P. Fig. 4 (a), (b), and (c) are graphs showing the values of the bright line luminance ratio when β (= (M / P) x 100) is expressed as a percentage. It is. Table 2 shows the values of the central luminance, and FIGS. 5A, 5B, and 5C are graphs showing them.

表３は反射部２３の角度γを３０度に設定し、突条２７の頂角Ｋ、Ｖ溝２２ｂの頂角α、Ｖ溝２２ｂの開放端の幅ＭのピッチＰに対する割合を％として表したβ（＝（Ｍ／Ｐ）×１００）を変更した場合の輝線輝度比の値を示し、図６（ａ），（ｂ），（ｃ）はそれらをグラフに表したものである。表４は同じく中心輝度の値を示し、図７（ａ），（ｂ），（ｃ）はそれらをグラフに表したものである。  Table 3 shows that the angle γ of the reflectingportion 23 is set to 30 degrees, and the ratio of the apex angle K of theridge 27, the apex angle α of theV groove 22b, and the width M of the open end of theV groove 22b to the pitch P is expressed as%. The bright line luminance ratio values when β (= (M / P) × 100) is changed are shown in FIGS. 6 (a), 6 (b), and 6 (c). Table 4 also shows the value of the central luminance, and FIGS. 7A, 7B, and 7C are graphs showing them.

なお、輝線輝度比とは、出射面１９の輝度ムラの最も大きな箇所、一般に採光部２１の仮想端面２１ａからの距離が導光板長さＬの２〜３割の位置において、導光板１４の幅方向における各点の輝度を測定した際の、輝度の極大値と極小値との比を意味する。即ち、図３に示すように、導光板１４の幅方向の端部からの距離を横軸ｘとし、輝度を縦軸にして測定値を表示すると、輝度は極大値と極小値を有するように変化するので、その極大値Ａと極小値Ｂとの比Ａ／Ｂが輝線輝度比となる。輝線輝度比の値が１に近いほど輝度ムラが小さいことを意味する。そして、輝線輝度比が１．１未満であれば実用上問題とならない。また、中心輝度は、出射面１９の輝度の最大値を１としたときの中心部の輝度の相対値を表す。そして、中心輝度が０．７未満では突条２７による輝度向上効果がないと見なせる。  The bright line luminance ratio is the width of thelight guide plate 14 at a position where the luminance unevenness of theemission surface 19 is the largest, generally at a position where the distance from thevirtual end surface 21a of thedaylighting portion 21 is 20-30% of the light guide plate length L. It means the ratio between the maximum value and the minimum value of luminance when the luminance of each point in the direction is measured. That is, as shown in FIG. 3, when the measured value is displayed with the horizontal axis x as the distance from the end of thelight guide plate 14 in the width direction and the luminance as the vertical axis, the luminance has a maximum value and a minimum value. Since it changes, the ratio A / B between the maximum value A and the minimum value B becomes the bright line luminance ratio. The closer the value of the bright line luminance ratio is to 1, the smaller the luminance unevenness. If the bright line luminance ratio is less than 1.1, there is no practical problem. The center luminance represents a relative value of the luminance of the central portion when the maximum luminance value of theemission surface 19 is 1. If the center luminance is less than 0.7, it can be considered that there is no luminance improvement effect by theprotrusion 27.

表１，２及び図４，５から、Ｖ溝２２ｂの頂角αを６０度に設定した場合、反射部２３の角度γが１５度〜４５度、突条２７の頂角Ｋが１３５度〜１５０度、Ｖ溝２２ｂの開放端の幅ＭのピッチＰに対する割合βが３０％〜７０％の範囲の組み合わせで、輝線が実用上問題とならず、突条２７の輝度向上効果が得られることが確認できる。また、βが５０％〜７０％のときには、輝度ムラがより小さくなる。  From Tables 1 and 2 and FIGS. 4 and 5, when the apex angle α of theV groove 22 b is set to 60 degrees, the angle γ of the reflectingportion 23 is 15 degrees to 45 degrees, and the apex angle K of theprotrusions 27 is 135 degrees to When the ratio β is 150 ° and the ratio β of the width M of the open end of theV groove 22b to the pitch P is in the range of 30% to 70%, the bright line does not become a practical problem, and the brightness improvement effect of theprotrusion 27 can be obtained. Can be confirmed. Further, when β is 50% to 70%, the luminance unevenness becomes smaller.

表３，４及び図６，７から、反射部２３の角度γを３０度に設定した場合、Ｖ溝２２ｂの頂角αが６０度〜９０度、突条２７の頂角Ｋが１３５度〜１５０度、Ｖ溝２２ｂの開放端の幅ＭとピッチＰとの割合βが３０％〜７０％のときに、輝線が実用上問題とならず、突条２７の輝度向上効果があることが確認できる。  From Tables 3 and 4 and FIGS. 6 and 7, when the angle γ of thereflection portion 23 is set to 30 degrees, the vertex angle α of theV groove 22 b is 60 degrees to 90 degrees, and the vertex angle K of theprotrusion 27 is 135 degrees to When the ratio β between the open end width M and the pitch P of the V-groove 22b is 30% to 70% at 150 degrees, it is confirmed that the bright line is not a problem in practice and the brightness of theprotrusion 27 is improved. it can.

また、表１〜４及び図４〜７から、突条２７の頂角Ｋが大きくなると輝度ムラが小さくなり、突条２７の頂角Ｋが小さくなると中心輝度が高くなることが確認できる。
この実施形態では以下の効果を有する。Further, from Tables 1 to 4 and FIGS. 4 to 7, it can be confirmed that the luminance unevenness decreases as the apex angle K of theridge 27 increases, and the central luminance increases as the apex angle K of theridge 27 decreases.
This embodiment has the following effects.

（１）導光板１４は、入射された光を拡散させる導入部１８と、導入部１８に連続して形成され、導入部１８から導入された光を出射する出射面１９及び出射面１９の反対側に形成された反射部２０を有する板状の採光部２１とを備えている。出射面１９には採光部２１の導入部１８側の仮想端面２１ａと直交する方向に延びるとともに頂角が１３５度〜１５０度のプリズム状の突条２７が複数設けられている。従って、拡散ドットを使用して点状光源１５から出射された光の指向性を緩和する構成に比較して、出射面１９からの出射光の集光性が高められる。  (1) Thelight guide plate 14 is formed continuously with theintroduction portion 18 for diffusing incident light, theemission surface 19 for emitting the light introduced from theintroduction portion 18, and the opposite of theemission surface 19. And a plate-shapeddaylighting portion 21 having areflection portion 20 formed on the side. Theexit surface 19 is provided with a plurality ofprismatic protrusions 27 extending in a direction orthogonal to thevirtual end surface 21a on theintroduction portion 18 side of thedaylighting portion 21 and having an apex angle of 135 degrees to 150 degrees. Therefore, the condensing property of the emitted light from theemission surface 19 is enhanced as compared with the configuration in which the directivity of the light emitted from the pointlight source 15 is reduced using the diffusion dots.

（２）導入部１８は、光の入射側から採光部２１側に向かって拡がる対称形状に形成されるとともにその両側面が端面と直交する面との成す角度γが１５度〜４５度に形成され、導入部１８の点状光源１５と対向する面は頂角αが６０度〜９０度のＶ溝２２ｂが形成されている。そして、Ｖ溝２２ｂの開放端の幅Ｍと、隣接するＶ溝２２ｂのピッチＰとの比Ｍ／Ｐが０．３〜０．７、即ちＭ／Ｐの割合βが３０％〜７０％に形成されている。従って、点状光源１５からの光が、導入部１８によって適度に拡散されるため、複数の点状光源１５の間と対応する箇所に暗部ができたり、逆に点状光源１５の正面に明部ができたりすることが抑制され、導光板１４から出射される光の点状光源１５近傍に発生する輝度ムラが低減する。そして、プリズム状の突条２７の頂角Ｋを１３５度〜１５０度とする構成を加えることで、複数の点状光源１５から出射された光を入射するとともに、面状に変換して出射する導光板１４を備えた面光源装置１３において、輝線の発生を抑制するとともに点状光源１５から導光板１４に入射された入射光の利用率を高めることができる。  (2) Theintroduction portion 18 is formed in a symmetrical shape that spreads from the light incident side toward thedaylighting portion 21 side, and an angle γ formed by a side surface of theintroduction portion 18 that is orthogonal to the end face is formed at 15 degrees to 45 degrees. In addition, a surface of the introducingportion 18 facing the pointlight source 15 is formed with aV groove 22b having an apex angle α of 60 degrees to 90 degrees. The ratio M / P between the width M of the open end of theV groove 22b and the pitch P of theadjacent V groove 22b is 0.3 to 0.7, that is, the ratio β of M / P is 30% to 70%. Is formed. Accordingly, since the light from the pointlight source 15 is appropriately diffused by the introducingportion 18, a dark portion is formed at a position corresponding to between the plurality of pointlight sources 15, or conversely, the light is bright in front of the pointlight source 15. The generation of a portion is suppressed, and luminance unevenness generated in the vicinity of the pointlight source 15 of the light emitted from thelight guide plate 14 is reduced. Then, by adding a configuration in which the apex angle K of the prism-shapedprotrusion 27 is set to 135 degrees to 150 degrees, the light emitted from the plurality of pointlight sources 15 is incident, converted into a planar shape, and emitted. In the surfacelight source device 13 including thelight guide plate 14, generation of bright lines can be suppressed and the utilization rate of incident light incident on thelight guide plate 14 from the pointlight source 15 can be increased.

（３）前記比Ｍ／Ｐを０．５〜０．７、即ち割合βを５０％〜７０％にすることにより、輝線が目立たずに輝度を高めるのが容易になる。
（４）採光部２１はプリズム状の突条２７が一体に形成されている。従って、プリズムシートを用いる必要がないため、面光源装置１３を構成する部品点数が少なくなって、組立工数を低減でき、製造コストを低減できる。導光板１４に突条２７を形成する必要があるが、導光板１４は金型を使用して射出成形等で製造されるため、金型のコストが多少高くなるが、多数の導光板１４を製造することにより、一枚当たりの導光板１４の製造コストは、突条２７を設けない導光板の製造コストと、プリズムシートの単価との合計より低くできる。(3) By setting the ratio M / P to 0.5 to 0.7, that is, the ratio β to 50% to 70%, it becomes easy to increase the luminance without making the bright line noticeable.
(4) Thedaylighting unit 21 is integrally formed with a prism-shapedprotrusion 27. Therefore, since it is not necessary to use a prism sheet, the number of parts constituting the surfacelight source device 13 is reduced, the number of assembling steps can be reduced, and the manufacturing cost can be reduced. Although it is necessary to form theprotrusions 27 on thelight guide plate 14, since thelight guide plate 14 is manufactured by injection molding or the like using a mold, the cost of the mold is slightly increased. By manufacturing, the manufacturing cost of thelight guide plate 14 per sheet can be made lower than the sum of the manufacturing cost of the light guide plate without theprotrusions 27 and the unit price of the prism sheet.

（５）採光部２１の裏面には、仮想端面２１ａに沿って延びるとともに導入部１８から入射された光を出射面１９から出射する方向に反射させる採光面２６ａを構成する溝２６が複数形成されている。従って、裏面にドットを設ける場合に比較して、出射面１９から出射される光の向きのばらつきを小さくすることができる。  (5) On the back surface of thedaylighting unit 21, a plurality ofgrooves 26 are formed that constitute thedaylighting surface 26a that extends along thevirtual end surface 21a and reflects the light incident from theintroduction unit 18 in the direction of exiting from theexit surface 19. ing. Therefore, the variation in the direction of the light emitted from theemission surface 19 can be reduced as compared with the case where dots are provided on the back surface.

（６）採光部２１の裏面に形成される溝２６が、反射部２０の断面形状が鋸歯状で、導光板１４の板厚ｔが、仮想端面２１ａ側から対向面２１ｂ側に指数関数的に減少するように形成されているため、採光部２１に入射した光をより効率良く、かつ出射面１９全体でのばらつきを抑制した状態で出射面１９から出射させることができる。また、板厚ｔが、前記関数Ｆでｎ＝１．５としたときの各部の値を満たすように設定されている場合は、より効率良く、かつ出射面１９全体でのばらつきを抑制した状態で出射面１９から出射させることができる。  (6) Thegroove 26 formed on the back surface of thedaylighting unit 21 has a sawtooth cross-sectional shape of thereflection unit 20, and the thickness t of thelight guide plate 14 is exponentially from thevirtual end surface 21a side to the opposingsurface 21b side. Since it is formed so as to decrease, the light incident on thedaylighting unit 21 can be emitted from theemission surface 19 in a more efficient manner while suppressing variations in theentire emission surface 19. Further, when the plate thickness t is set so as to satisfy the value of each part when n = 1.5 in the function F, the state where the variation in theentire emission surface 19 is suppressed more efficiently. Can be emitted from theemission surface 19.

（７）面光源装置１３は拡散シート１７を備えている。従って、導光板１４において輝線が完全には防止できない場合でも、導光板１４から出射された光が拡散シート１７を通過して液晶パネル１２に入射する際には、輝線を肉眼で判別できない状態にすることができる。  (7) The surfacelight source device 13 includes adiffusion sheet 17. Therefore, even when the bright line cannot be completely prevented in thelight guide plate 14, when the light emitted from thelight guide plate 14 passes through thediffusion sheet 17 and enters theliquid crystal panel 12, the bright line cannot be distinguished with the naked eye. can do.

実施の形態は前記に限定されるものではなく、例えば、次のように具体化してもよい。
○ 入射部２２に形成される複数のＶ溝２２ｂの開放端の幅Ｍ及びＶ溝２２ｂのピッチＰの値は同じに限らず異なる値のＶ溝２２ｂが混在してもよい。その場合は、幅ＭのピッチＰに対する割合β％を算出する際に、平均値で算出し、平均値が３０％〜７０％、好ましくは５０％〜７０％であればよい。The embodiment is not limited to the above, and may be embodied as follows, for example.
The values of the width M of the open ends of the plurality ofV grooves 22b formed in the incident portion 22 and the pitch P of theV grooves 22b are not limited to the same, andV grooves 22b having different values may be mixed. In that case, when calculating the ratio β% of the width M to the pitch P, it is calculated as an average value, and the average value may be 30% to 70%, preferably 50% to 70%.

○ 突条２７は断面が二等辺三角形状のプリズムに限らず、プリズム状であればよい。ここでプリズム状とは、断面が二等辺三角形状のプリズム及び該プリズムに近い形状を意味し、例えば、図８（ａ）に示すように、断面二等辺三角形状のプリズムの二つの斜面２７ａの基部側が曲面に形成された形状や、図８（ｂ）に示すように、断面二等辺三角形のプリズムの頂角の部分が曲面に形成された形状としてもよい。図８（ｂ）に示す突条２７の場合、頂角Ｋは二つの斜面２７ａの平面部分が成す角度となる。これらの突条２７を設けた場合も、三角プリズムで構成された突条２７を設けた場合とほぼ同様な効果が得られる。  Theridge 27 is not limited to a prism having a cross section of an isosceles triangle, but may be a prism shape. Here, the prism shape means a prism having a cross section of an isosceles triangle and a shape close to the prism. For example, as shown in FIG. A shape in which the base side is formed in a curved surface or a shape in which the apex angle portion of a prism having an isosceles triangle cross section is formed in a curved surface as shown in FIG. In the case of theridge 27 shown in FIG. 8B, the apex angle K is an angle formed by the plane portions of the twoinclined surfaces 27a. When theseprotrusions 27 are provided, substantially the same effect as that when theprotrusions 27 formed of triangular prisms are provided can be obtained.

○ プリズム状には、図８（ｃ），（ｄ）に示すように、二つの斜面２７ａ全体が曲面で構成された形状も含む。図８（ｃ）に示すシリンドリカルな突条２７では、長手方向と直交する断面において、突条２７の基端の両側における２本の接線ＣＬの成す角度が頂角Ｋとなり、図８（ｄ）に示す逆シリンドリカルな突条２７では、長手方向と直交する断面において、隣接する突条２７の頂部における接線ＣＬの成す角度が頂角Ｋとなる。これらの突条２７を設けた場合も、三角プリズムで構成された突条２７を設けた場合とほぼ同様な効果が得られる。  As shown in FIGS. 8C and 8D, the prism shape includes a shape in which the entire twoinclined surfaces 27a are curved surfaces. In thecylindrical ridge 27 shown in FIG. 8C, in the cross section orthogonal to the longitudinal direction, the angle formed by the two tangent lines CL on both sides of the base end of theridge 27 becomes the apex angle K, and FIG. In the reversecylindrical ridge 27 shown in FIG. 2, the angle formed by the tangent line CL at the apex of theadjacent ridge 27 is the apex angle K in the cross section orthogonal to the longitudinal direction. When theseprotrusions 27 are provided, substantially the same effect as that when theprotrusions 27 formed of triangular prisms are provided can be obtained.

○ 突条２７は採光部２１、即ち導光板１４と一体に形成されている構成に限らない。例えば、プリズム状の突条２７が所定ピッチで形成されたプリズムシートを採光部２１の出射面１９に接着剤で接着してもよい。接着剤には、透明な紫外線硬化型接着剤や高分子系接着剤等が使用される。また、プリズムシートを採光部２１の出射面１９に接着剤で接着せずに、出射面１９上に載置する構成としてもよい。  Theridge 27 is not limited to the structure formed integrally with thedaylighting unit 21, that is, thelight guide plate 14. For example, a prism sheet in which theprismatic protrusions 27 are formed at a predetermined pitch may be bonded to theemission surface 19 of thedaylighting unit 21 with an adhesive. As the adhesive, a transparent ultraviolet curable adhesive, a polymer adhesive, or the like is used. Alternatively, the prism sheet may be placed on theemission surface 19 without being bonded to theemission surface 19 of thedaylighting unit 21 with an adhesive.

○ 採光部２１は、板厚ｔがマクロ的に見て仮想端面２１ａ側から対向面２１ｂ側に向かって次第に薄くなるほぼ楔状に限らず、マクロ的に見て一定な形状としてもよい。
○ 採光部２１の出射面１９と反対側に設けられる反射部２０は、採光面２６ａと傾斜面２６ｂとが交互に連続する鋸歯状の溝２６を備えた構成に限らず、導入部１８から入射されて板厚方向と直交する方向に進む光を出射面１９に向けて全反射させる斜面を備えた構成であればよい。例えば、仮想端面２１ａと平行に延びるＶ溝や断面直角三角形状の溝が複数平行に形成された構成や、出射面１９と反対側の面に円錐状あるいは角錐状の凹部を設けることで形成された複数のマイクロレンズを備えた構成としてもよい。Thedaylighting unit 21 is not limited to a substantially wedge shape in which the plate thickness t gradually decreases from thevirtual end surface 21a side to the opposingsurface 21b side when viewed macroscopically, but may have a constant shape when viewed macroscopically.
The reflectingpart 20 provided on the side opposite to theemission surface 19 of thedaylighting unit 21 is not limited to the configuration provided with the sawtooth-shapedgrooves 26 in which the daylighting surfaces 26a and theinclined surfaces 26b are alternately continuous, and is incident from theintroduction unit 18. Any configuration may be used as long as it has an inclined surface that totally reflects the light traveling in the direction orthogonal to the plate thickness direction toward theemission surface 19. For example, it is formed by a configuration in which a plurality of V-grooves extending in parallel with thevirtual end surface 21a or grooves having a right-angled triangular section are formed in parallel, or by providing a conical or pyramidal concave portion on the surface opposite to theemission surface 19. Alternatively, a configuration including a plurality of microlenses may be employed.

〇 面光源装置１３において拡散シート１７を省略してもよい。拡散シート１７を設ける方が、面光源装置１３の出射面全体の輝度ムラを低くすることができる。しかし、面光源装置１３が使用される表示装置に要求される表示部の精細度によっては、拡散シート１７を省略しても、輝度ムラが気にならない状態に抑制できる。  Thediffusion sheet 17 may be omitted from the surfacelight source device 13. The provision of thediffusion sheet 17 can reduce the luminance unevenness of the entire emission surface of the surfacelight source device 13. However, depending on the definition of the display unit required for the display device using the surfacelight source device 13, even if thediffusion sheet 17 is omitted, it is possible to suppress the brightness unevenness from being noticed.

○ 導光板１４に使用される材料としては、透明で成形型を使用して加工をすることができるものが好ましく、例えば、アクリル樹脂に限らず、ポリカーボネート、ポリスチレン、ＭＳ樹脂（メタクリルスチレン樹脂）、シクロオレフィン樹脂等が使用される。  ○ The material used for thelight guide plate 14 is preferably a transparent material that can be processed using a mold, for example, not only acrylic resin, but also polycarbonate, polystyrene, MS resin (methacrylstyrene resin), A cycloolefin resin or the like is used.

○ 導光板１４をガラス板で形成してもよい。しかし、ガラス板に突条２７や溝２６等をエッチングで加工するのはコストが高くなる。
○ 面光源装置１３はバックライト用に限らず、他の照明装置やディスプレイ装置の発光源として使用してもよい。○ Thelight guide plate 14 may be formed of a glass plate. However, it is expensive to process theprotrusions 27 and thegrooves 26 on the glass plate by etching.
The surfacelight source device 13 is not limited to the backlight, but may be used as a light source for other illumination devices or display devices.

以下の技術的思想（発明）は前記実施の形態から把握できる。
（１）請求項１〜請求項４のいずれか一項に記載の発明において、前記採光部は反射部として、採光部の入射側仮想端面と平行に延びるとともに前記入射された光を前記出射面から出射する方向に反射させる採光面を構成する溝が複数形成されている。The following technical idea (invention) can be understood from the embodiment.
(1) In the invention according to any one ofclaims 1 to 4, the daylighting unit is a reflection unit, and extends in parallel with an incident side virtual end surface of the daylighting unit and transmits the incident light to the emission surface. A plurality of grooves constituting a daylighting surface to be reflected in the direction of emission from the light source are formed.

（２）前記技術的思想（１）に記載の発明において、前記採光部における導光板の各溝の最深部から前記出射面まで距離としての板厚ｔが、前記仮想端面側から対向面側へと指数関数的に単調減少するように設定されている。  (2) In the invention described in the technical idea (1), a plate thickness t as a distance from the deepest part of each groove of the light guide plate in the daylighting unit to the emission surface is from the virtual end surface side to the opposing surface side. And is set to decrease monotonically exponentially.

（３）入射された光を拡散させる導入部と、前記導入部に連続して形成され、前記導入部から導入された光を出射する出射面及び出射面の反対側に形成された反射部を有する板状の採光部とを備え、前記出射面には前記採光部の導入部側の仮想端面と直交する方向に延びるとともに頂角が１３５度〜１５０度のプリズム状の突条が複数設けられ、前記導入部は、光の入射側から前記採光部側に向かって拡がる対称形状に形成されるとともにその両側面が前記仮想端面と直交する面との成す角度が１５度〜４５度に形成され、前記導入部の前記点状光源と対向する面には導光板の厚さ方向に延びる複数のＶ溝が形成され、前記Ｖ溝は頂角が６０度〜９０度、開放端の幅Ｍと隣接するＶ溝のピッチＰとの比Ｍ／Ｐが０．３〜０．７に形成されている導光板。  (3) An introduction part that diffuses incident light, an emission surface that is formed continuously from the introduction part, emits light introduced from the introduction part, and a reflection part that is formed on the opposite side of the emission surface. A plurality of prismatic protrusions extending in a direction perpendicular to the virtual end surface on the introduction portion side of the daylighting section and having an apex angle of 135 degrees to 150 degrees. The introduction part is formed in a symmetric shape that spreads from the light incident side toward the daylighting part side, and an angle formed between a side surface of the introduction part and a surface orthogonal to the virtual end face is 15 degrees to 45 degrees. A plurality of V-grooves extending in the thickness direction of the light guide plate are formed on a surface of the introducing portion facing the point light source, and the V-groove has an apex angle of 60 to 90 degrees and an open end width M. The ratio M / P with the pitch P of the adjacent V groove is 0.3 to 0.7. The light guide plate.

（ａ）は一実施形態の導光板と点状光源の関係を示す模式斜視図、（ｂ）は導入部と点状光源の関係を示す模式平面図、（ｃ）は液晶表示装置の模式図。(A) is a schematic perspective view which shows the relationship between the light-guide plate of one Embodiment, and a point light source, (b) is a schematic top view which shows the relationship between an introducing | transducing part and a point light source, (c) is a schematic diagram of a liquid crystal display device. .（ａ）は導光板の模式平面図、（ｂ）は模式側面図、（ｃ）は採光部の部分模式側面図。(A) is a schematic plan view of a light-guide plate, (b) is a schematic side view, (c) is a partial schematic side view of a lighting part.輝線輝度比の求め方を示すグラフ。The graph which shows how to obtain | require an emission line luminance ratio.（ａ）〜（ｃ）は輝線輝度比とプリズム状突条の頂角との関係を示すグラフ。(A)-(c) is a graph which shows the relationship between a bright line luminance ratio and the apex angle of a prismatic protrusion.（ａ）〜（ｃ）は中心輝度とプリズム状突条の頂角との関係を示すグラフ。(A)-(c) is a graph which shows the relationship between center brightness | luminance and the apex angle of a prism-shaped protrusion.（ａ）〜（ｃ）は輝線輝度比とプリズム状突条の頂角との関係を示すグラフ。(A)-(c) is a graph which shows the relationship between a bright line luminance ratio and the apex angle of a prismatic protrusion.（ａ）〜（ｃ）は中心輝度とプリズム状突条の頂角との関係を示すグラフ。(A)-(c) is a graph which shows the relationship between center brightness | luminance and the apex angle of a prism-shaped protrusion.（ａ）〜（ｄ）は突条の別の実施形態を示す模式図。(A)-(d) is a schematic diagram which shows another embodiment of a protrusion.従来技術の面光源装置の分解模式斜視図。The disassembled model perspective view of the surface light source device of a prior art.

符号の説明Explanation of symbols

α，Ｋ…頂角、γ，θ１，θ２…角度、Ｍ…幅、Ｐ…ピッチ、１３…面光源装置、１４…導光板、１５…点状光源、１８…導入部、１９…出射面、２０…反射部、２１…採光部、２１ａ…仮想端面、２２ｂ…Ｖ溝、２３…側面としての反射部、２４…面、２７…突条。  α, K ... vertex angle, γ, θ1, θ2 ... angle, M ... width, P ... pitch, 13 ... surface light source device, 14 ... light guide plate, 15 ... point light source, 18 ... introduction part, 19 ... exit surface, DESCRIPTION OFSYMBOLS 20 ... Reflection part, 21 ... Daylighting part, 21a ... Virtual end surface, 22b ... V-groove, 23 ... Reflection part as side, 24 ... Surface, 27 ... Projection.

Claims (4)

Translated fromJapanese

複数の点状光源から出射された光を入射するとともに、面状に変換して出射する導光板を備えた面光源装置であって、
前記導光板は、入射された光を拡散させる導入部と、前記導入部に連続して形成され、前記導入部から導入された光を出射する出射面及び出射面の反対側に形成された反射部を有する板状の採光部とを備え、前記出射面には前記採光部の導入部側の仮想端面と直交する方向に延びるとともに頂角が１３５度〜１５０度のプリズム状の突条が複数設けられ、前記導入部は、光の入射側から前記採光部側に向かって拡がる対称形状に形成されるとともにその両側面が前記仮想端面と直交する面との成す角度が１５度〜４５度に形成され、前記導入部の前記点状光源と対向する面には導光板の厚さ方向に延びる複数のＶ溝が形成され、前記Ｖ溝は頂角が６０度〜９０度、開放端の幅Ｍと隣接するＶ溝のピッチＰとの比Ｍ／Ｐが０．３〜０．７に形成されている面光源装置。A surface light source device that includes a light guide plate that receives light emitted from a plurality of point light sources, converts the light into a planar shape, and emits the light.
The light guide plate is formed continuously with the introduction part for diffusing incident light, the emission surface for emitting the light introduced from the introduction part, and a reflection formed on the opposite side of the emission surface. A plurality of prismatic ridges extending in a direction perpendicular to the virtual end surface on the introduction portion side of the daylighting section and having an apex angle of 135 degrees to 150 degrees. The introduction part is formed in a symmetric shape that spreads from the light incident side toward the daylighting part side, and the angle formed between the side surfaces of the introduction part and the surface perpendicular to the virtual end face is 15 degrees to 45 degrees. A plurality of V-grooves extending in the thickness direction of the light guide plate are formed on a surface of the introducing portion facing the point light source, and the V-groove has an apex angle of 60 degrees to 90 degrees and an open end width. The ratio M / P between M and the pitch P of the adjacent V groove is 0.3 to 0.7. It is to have the surface light source device. 前記比Ｍ／Ｐは０．５〜０．７に形成されている請求項１に記載の面光源装置。  The surface light source device according to claim 1, wherein the ratio M / P is formed to be 0.5 to 0.7. 前記プリズム状の突条は前記採光部と別体に形成されたプリズムシートで構成されている請求項１又は請求項２に記載の面光源装置。  The surface light source device according to claim 1, wherein the prism-shaped protrusion is formed of a prism sheet formed separately from the daylighting unit. 前記採光部は前記プリズム状の突条が一体に形成されている請求項１又は請求項２に記載の面光源装置。  The surface light source device according to claim 1, wherein the daylighting unit is integrally formed with the prism-shaped protrusions.

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