JP4452725B2 - Surface lighting device - Google Patents

Surface lighting device Download PDF

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JP4452725B2
JP4452725B2 JP2007000532A JP2007000532A JP4452725B2 JP 4452725 B2 JP4452725 B2 JP 4452725B2 JP 2007000532 A JP2007000532 A JP 2007000532A JP 2007000532 A JP2007000532 A JP 2007000532A JP 4452725 B2 JP4452725 B2 JP 4452725B2
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rod
shaped
light
light source
lens
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JP2008166234A (en
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孝浩 伊藤
俊幸 近藤
嘉史 川口
貞一郎 高野
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Stanley Electric Co Ltd
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Description

本発明は、面照明装置に関するものであり、詳しくは、いわゆる直下型と呼ばれる面照明装置に関する。   The present invention relates to a surface illumination device, and more particularly, to a surface illumination device called a so-called direct type.

従来、液晶表示パネル等の非発光表示素子あるいは看板、写真フィルム等の透光性表示体の照明用光源となる面照明装置として、導光板の側面から入射した光で該導光板の平面側に載置された非発光表示素子あるいは透光性表示体を照射する、いわゆるサイドライト型と呼ばれる面照明装置と、光拡散板の一方の平面側から入射した光で該光拡散板の他方の平面側に載置された非発光表示素子あるいは透光性表示体を照射する、いわゆる直下型と呼ばれる面照明装置がある。以下、非発光表示素子あるいは透光性表示体のうち、非発光表示素子である液晶表示パネルを例に取る。   Conventionally, as a surface illumination device serving as a light source for illuminating a non-light emitting display element such as a liquid crystal display panel or a translucent display body such as a signboard or a photographic film, light incident from the side surface of the light guide plate is applied to the plane side of the light guide plate. A so-called side light type surface illumination device that irradiates a mounted non-light emitting display element or translucent display, and the other plane of the light diffusion plate by light incident from one plane side of the light diffusion plate There is a so-called direct-type surface illumination device that irradiates a non-light emitting display element or a translucent display placed on the side. Hereinafter, a liquid crystal display panel which is a non-light-emitting display element among non-light-emitting display elements or translucent displays is taken as an example.

前者の場合は、光源を導光板の側面に沿って配設するために面照明装置の厚みを薄くでき、その結果、面照明装置を備えた液晶表示装置が搭載された各種機器の薄型化を図ることが可能となる。   In the former case, since the light source is arranged along the side surface of the light guide plate, the thickness of the surface illumination device can be reduced, and as a result, various devices equipped with the liquid crystal display device equipped with the surface illumination device can be made thinner. It becomes possible to plan.

ところで、液晶表示パネルの大型化、および液晶表示パネルのカラー化による透過率の低下などに伴い、液晶表示パネルによって鮮明な表示を得るためには該液晶表示パネルを全面に亘って均一に且つ明るく照射する面照明装置が必要となる。この点、サイドライト型の面照明装置は光源の配設領域に制約があり、液晶表示パネルによって鮮明な表示を得るための十分な光量を導光板内に導入することが困難になってきた。   By the way, in order to obtain a clear display by the liquid crystal display panel as the liquid crystal display panel is enlarged and the transmittance is lowered due to the color of the liquid crystal display panel, the liquid crystal display panel is uniformly and brightly provided over the entire surface. A surface illumination device for irradiation is required. In this respect, the sidelight type surface illumination device has a limitation in the light source arrangement region, and it has become difficult to introduce a sufficient amount of light for obtaining a clear display by the liquid crystal display panel into the light guide plate.

これに対し、直下型の面照明装置は、光拡散板の一方の平面側に載置された液晶表示パネルを光拡散板の他方の平面側に配設された光源によって照明するものであり、サイドライト型に比べて多くの照射光量の確保が可能となると共に導光板が不要な分だけ軽量化を図ることが可能となるために、液晶表示パネルの大型化、およびカラー化に対応できる照明装置である。   On the other hand, the direct type surface illumination device illuminates a liquid crystal display panel placed on one plane side of the light diffusion plate with a light source disposed on the other plane side of the light diffusion plate, Compared to the sidelight type, it is possible to secure a large amount of irradiation light and to reduce the weight of the light guide plate as much as necessary. Device.

直下型の面照明装置の具体例としては、従来、図9に示すような構成のものが提案されている。それは、単数または平行に並設された複数の線状光源30の夫々の周囲の一部を囲むように連続するリフレクタ31が配設され、光源30およびリフレクタ31の上方に該光源30およびリフレクタ31を覆うように光拡散板32およびプリズムシート33が配設されたものである。   As a specific example of the direct type surface illumination device, a structure having a configuration as shown in FIG. 9 has been proposed. The reflector 31 is arranged so as to surround a part of the periphery of each of the plurality of linear light sources 30 arranged in parallel or in parallel, and the light source 30 and the reflector 31 are disposed above the light source 30 and the reflector 31. A light diffusion plate 32 and a prism sheet 33 are disposed so as to cover the surface.

そして、リフレクタ31の光源30に対向する側の面には光反射面34が形成され、該光反射面34は一般的に白色塗装を施したり、あるいは発泡樹脂シート等を貼付した光拡散反射面となっている。   A light reflecting surface 34 is formed on the surface of the reflector 31 that faces the light source 30, and the light reflecting surface 34 is generally white-coated or a light diffusing reflecting surface to which a foamed resin sheet or the like is attached. It has become.

この場合、光源30から発せられて直接光拡散板32に至った直接光、および光源30から発せられてリフレクタ31の光反射面34で反射されて光拡散板32に至った反射光は共に、光拡散板32によって拡散され、更にプリズムシート33によって集光性される。   In this case, both the direct light emitted from the light source 30 and directly reaching the light diffusion plate 32 and the reflected light emitted from the light source 30 and reflected by the light reflecting surface 34 of the reflector 31 and reaching the light diffusion plate 32 are both: The light is diffused by the light diffusion plate 32 and further condensed by the prism sheet 33.

つまり、光拡散板32は面輝度分布の均一化を図り、プリズムシート33は正面輝度の向上を担うものである(例えば、特許文献1参照。)。   That is, the light diffusing plate 32 makes the surface luminance distribution uniform, and the prism sheet 33 is responsible for improving the front luminance (for example, see Patent Document 1).

また、図10に示すように、光源30から発せられて光拡散板32に至る光の光量分布を均一化するために、光源30に反射、屈折、拡散等の複数の光学機能面を備えたレンズ35を取付けた構成のものもある(例えば、特許文献2参照。)。
特開平09−33706号公報 特開2006−196458号公報
As shown in FIG. 10, the light source 30 is provided with a plurality of optical function surfaces such as reflection, refraction, and diffusion in order to make the light quantity distribution of the light emitted from the light source 30 and reaching the light diffusion plate 32 uniform. There is also a configuration in which a lens 35 is attached (for example, see Patent Document 2).
JP 09-33706 A JP 2006-196458 A

しかしながら「特許文献1」で提案された方法は、材料費の削減および生産性の向上等によって製造コストの低減を図る場合、光源の数を減らすことも手法の一つになる。但し、光源の数が減ると互いに隣接する光源同士の間隔を広げる必要があり、その際、光源から発せられて光拡散板に至る光の光量分布を均一化するためには光源と光拡散板の距離を長くする必要がある。   However, the method proposed in “Patent Document 1” is one of the methods for reducing the number of light sources when the manufacturing cost is reduced by reducing the material cost and improving the productivity. However, if the number of light sources is reduced, it is necessary to widen the distance between adjacent light sources. At that time, in order to make the light quantity distribution of light emitted from the light sources and reaching the light diffusion plate uniform, the light source and the light diffusion plate It is necessary to lengthen the distance.

すると、光源から光拡散板に至る光路長が長くなって光拡散板に至る光量が減衰すると共に、面照明装置の厚みが増大することになる。   Then, the optical path length from the light source to the light diffusing plate becomes longer, the amount of light reaching the light diffusing plate is attenuated, and the thickness of the surface illumination device is increased.

また、「特許文献2」で提案された方法は、レンズ内および面照明装置の空間内で複数回の反射が繰返され、その間の導光損失によって光拡散板に至る光量が減衰する。   In the method proposed in “Patent Document 2”, reflection is repeated a plurality of times in the lens and in the space of the surface illumination device, and the amount of light reaching the light diffusion plate is attenuated due to light guide loss therebetween.

その結果、上記構成の従来の面照明装置は、寸法、形状、光源数などの制約によって面照明装置の光出射面となる、光拡散板の光源の反対側の面において、所望の輝度および輝度均斉度などの光学特性が得られない可能性がある。   As a result, the conventional surface illumination device having the above-described configuration has desired luminance and luminance on the surface opposite to the light source of the light diffusing plate, which becomes the light emission surface of the surface illumination device due to restrictions such as size, shape, and the number of light sources. Optical properties such as uniformity may not be obtained.

また、上記いずれの面照明装置においても、光源直上近傍の輝度が最も高く、光源の直上から離れるにつれて輝度が低下していく輝度勾配が形成され、面内輝度分布の均一性が損なわれて所望する輝度均斉度を得ることが難しい。   In any of the above surface illumination devices, a luminance gradient is formed in which the luminance in the vicinity immediately above the light source is the highest, and the luminance decreases as the distance from directly above the light source decreases, and the uniformity of the in-plane luminance distribution is impaired and desired. It is difficult to obtain brightness uniformity.

そこで、本発明は上記問題に鑑みて創案なされたもので、その目的とするところは、非発光表示素子あるいは透光性表示体を照明する直下型の面照明装置において、比較的簡易な構造で生産性に優れると共に、光源光の利用効率の向上で輝度が高く且つ所望の輝度均斉度を容易に得ることができ、光学的にも優れた特性を有する面照明装置を提供することにある。   Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to provide a relatively simple structure in a direct type surface illumination device that illuminates a non-light emitting display element or a translucent display. An object of the present invention is to provide a surface illumination device that is excellent in productivity, has high luminance by improving the utilization efficiency of light source light, can easily obtain desired luminance uniformity, and has excellent optical characteristics.

上記課題を解決するために、本発明の請求項1に記載された発明は、単数または平行に並設された複数の棒状光源と、前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、 前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L(θ/Θ)の関数に基づいて形成されていることを特徴とするものである。 In order to solve the above-described problems, the invention described in claim 1 of the present invention includes a plurality of bar-shaped light sources arranged in parallel or singularly and in parallel and fixed in a state of being substantially in close contact with the respective bar-shaped light sources. And a reflector disposed so as to surround a part of the rod-shaped light source and the rod-shaped lens, and the rod-shaped lens is obtained by cutting the rod-shaped lens along a plane perpendicular to the longitudinal direction of the rod-shaped lens. When the cross-section of the circular arc and the straight line passing through the center of the circular arc located on the outer side of the circular arc, the curve is in the opposite direction to the center of the circular arc and connected on the symmetrical axis a curve with a convex shape, Ri Do two straight lines connecting the ends to each other of each of the arcs and the curves, the rod-shaped light sources, the bar lens, and above the reflector, the light diffusion plate, a light diffusion sheet and a prism Sheet Out with a light distribution control unit consisting of at least one surface of the linear light source side of the light distribution control unit the light distribution control unit with a linear light source located the rod-shaped light sources in the center of the rod-shaped light sources Is positioned so as to be substantially perpendicular to the axis of symmetry passing through the center of the rod-shaped light source, L is a distance that is half of the interval between the linear light sources adjacent to each other, and the rays emitted from the linear light source The angle with respect to the axis of symmetry is θ, the angle with respect to the axis of symmetry of the light beam that is emitted from the linear light source and reaches the end of the cross-section arc of the rod-shaped lens is Θ, and the angle from the linear light source to the axis of symmetry A light exit surface that is emitted at an angle of θ, is incident on the rod lens from the light incident surface formed by the cross-section arc of the rod-shaped lens, is guided in the rod-shaped lens, and is formed by the cross-section convex curve of the rod-shaped lens. Out of When the distance from the symmetry axis at the position where the light beam reaches the surface on the linear light source side of the light distribution control unit is L (θ), the cross-sectional convex curve of the rod-shaped lens is L (θ) = L (θ / Θ) is formed based on the function .

また、本発明の請求項2に記載された発明は、単数または平行に並設された複数の棒状光源と、前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L√(θ/Θ)の関数に基づいて形成されていることを特徴とするものである。 Further, the invention described in claim 2 of the present invention includes a plurality of rod-shaped light sources arranged in parallel or in parallel, and rod-shaped lenses arranged and fixed in parallel in a state of being substantially in close contact with the respective rod-shaped light sources, The rod-shaped light source and a reflector disposed so as to surround a part of the rod-shaped lens are provided, and the rod-shaped lens has a circular cross section when the rod-shaped lens is cut by a plane perpendicular to the longitudinal direction of the rod-shaped lens. And a curve having two convex shapes which are located outside the arc and have a straight line passing through the center of the arc as a symmetric axis, curved in the opposite direction to the center of the arc and connected on the symmetric axis. And at least one of a light diffusing plate, a light diffusing sheet, and a prism sheet above the rod-shaped light source, the rod-shaped lens, and the reflector. A light distribution control unit, wherein the rod-shaped light source is a linear light source located at the center of the rod-shaped light source, and the light distribution control unit is a surface on the linear light source side of the light distribution control unit. When positioned so as to be substantially perpendicular to the symmetry axis passing through the center of the light source, L is a distance that is half the interval between the linear light sources adjacent to each other, and the light beam emitted from the linear light source is relative to the symmetry axis. The angle is θ, the angle with respect to the symmetry axis of the light beam that is emitted from the linear light source and reaches the end of the cross-section arc of the rod-shaped lens is Θ, and the angle from the linear light source to the symmetry axis is θ Light emitted from the light incident surface formed by the cross-section arc of the rod-shaped lens and incident on the rod-shaped lens, guided through the rod-shaped lens, and emitted from the light emission surface formed by the convex curve of the cross-section of the rod-shaped lens. However, When the distance from the symmetry axis at the position of the control unit that reaches the surface of the linear light source is L (θ), the cross-sectional convex curve of the rod-shaped lens is L (θ) = L√ (θ / Θ ) it is characterized in that you have been formed based on a function of.

また、本発明の請求項3に記載された発明は、単数または平行に並設された複数の棒状光源と、前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L[3(θ/Θ)exp{−7(θ/Θ)}+(θ/Θ)]の関数に基づいて形成されていることを特徴とするものである。 The invention described in claim 3 of the present invention includes a plurality of rod-shaped light sources arranged in parallel or in parallel, and rod-shaped lenses arranged in parallel and fixed in a state of being in close contact with each of the rod-shaped light sources, The rod-shaped light source and a reflector disposed so as to surround a part of the rod-shaped lens are provided, and the rod-shaped lens has a circular cross section when the rod-shaped lens is cut by a plane perpendicular to the longitudinal direction of the rod-shaped lens. And a curve having two convex shapes which are located outside the arc and have a straight line passing through the center of the arc as a symmetric axis, curved in the opposite direction to the center of the arc and connected on the symmetric axis. And at least one of a light diffusing plate, a light diffusing sheet, and a prism sheet above the rod-shaped light source, the rod-shaped lens, and the reflector. A light distribution control unit, wherein the rod-shaped light source is a linear light source located at the center of the rod-shaped light source, and the light distribution control unit is a surface on the linear light source side of the light distribution control unit. When positioned so as to be substantially perpendicular to the symmetry axis passing through the center of the light source, L is a distance that is half the interval between the linear light sources adjacent to each other, and the light beam emitted from the linear light source is relative to the symmetry axis. The angle is θ, the angle with respect to the symmetry axis of the light beam that is emitted from the linear light source and reaches the end of the cross-section arc of the rod-shaped lens is Θ, and the angle from the linear light source to the symmetry axis is θ Light emitted from the light incident surface formed by the cross-section arc of the rod-shaped lens and incident on the rod-shaped lens, guided through the rod-shaped lens, and emitted from the light emission surface formed by the convex curve of the cross-section of the rod-shaped lens. However, When the distance from the symmetry axis at the position of the control unit that reaches the surface of the linear light source is L (θ), the convex cross-sectional curve of the rod-shaped lens is L (θ) = L [3 (θ / Θ) exp {−7 (θ / Θ)} + (θ / Θ)] .

また、本発明の請求項4に記載された発明は、請求項1から3のいずれか1項において、前記棒状レンズは、該棒状レンズの前記円弧の中心が前記棒状光源の外周円の中心と略同一位置となるように前記棒状光源に並設、固定されていることを特徴とするものである。 The invention described in claim 4 of the present invention is the rod lens according to any one of claims 1 to 3 , wherein the center of the arc of the rod lens is the center of the outer circumference of the rod light source. It is characterized by being arranged and fixed to the rod-shaped light source so as to be in substantially the same position .

また、本発明の請求項5に記載された発明は、請求項1から4のいずれか1項において、前記棒状レンズは前記棒状光源と略同一の長さを有していることを特徴とするものである。 Further, the invention described in claim 5 of the present invention is characterized in that, in any one of claims 1 to 4 , the rod-shaped lens has substantially the same length as the rod-shaped light source. Is.

また、本発明の請求項6に記載された発明は、請求項1から5のいずれか1項において、前記棒状レンズが形成する照度分布は、前記夫々の棒状光源の直上近傍において低く、互いに隣接する前記棒状光源方向に向かうにつれて徐々に高くなり、互いに隣接する前記棒状光源同士の間隔の半分の位置の直上近傍において最高となり、最外側に位置する棒状光源の外側では一端上昇した後、急速に減衰することを特徴とするものである。 Further, in the invention described in claim 6 of the present invention, in any one of claims 1 to 5, the illuminance distribution formed by the rod-shaped lens is low in the vicinity immediately above each of the rod-shaped light sources and adjacent to each other. Gradually increases toward the direction of the rod-shaped light source, becomes highest in the vicinity immediately above half of the interval between the rod-shaped light sources adjacent to each other, rises at one end outside the rod-shaped light source located on the outermost side, and then rapidly It is characterized by attenuation .

また、本発明の請求項7に記載された発明は、請求項1から6のいずれか1項において、前記棒状光源は熱陰極蛍光ランプであることを特徴とするものである。 According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the rod-shaped light source is a hot cathode fluorescent lamp .

本発明の面照明装置は、棒状光源に、断面形状が円弧と、円弧の外側に位置し、円弧の中心を通る直線を対称軸とする、夫々円弧の中心と反対方向に湾曲し且つ対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線で形成された棒状レンズを並設、固定した。   The surface illumination device according to the present invention has a bar-shaped light source that is curved in a direction opposite to the center of the arc, with the cross-sectional shape being an arc and a straight line passing outside the arc and passing through the center of the arc. A rod-shaped lens formed by two curved lines having two convex shapes connected to each other and two straight lines connecting the respective ends of the circular arc and the curved line are arranged and fixed.

そして、棒状光源から出射した光は棒状レンズの断面円弧の光入射面から棒状レンズ内に入射し、棒状レンズ内を導光されて断面凸形状曲面の光出射面で屈折されて外部に出射され、所望の照度分布を形成する。   Then, the light emitted from the rod-shaped light source enters the rod-shaped lens from the light incident surface of the cross-sectional arc of the rod-shaped lens, is guided through the rod-shaped lens, is refracted by the light emitting surface of the convex curved surface, and is emitted to the outside. , To form a desired illuminance distribution.

その結果、比較的簡易な構造で生産性に優れると共に、光源光の利用効率の向上で輝度が高く且つ所望の輝度均斉度を容易に得ることができ、光学的にも優れた特性を有する面照明装置を実現することができた。   As a result, it has a relatively simple structure and is excellent in productivity, and can be easily obtained with high luminance and desired luminance uniformity by improving the utilization efficiency of light source light, and has excellent optical characteristics. A lighting device could be realized.

以下、この発明の好適な実施形態を図1から図8を参照しながら、詳細に説明する(同一部分については同じ符号を付す)。尚、以下に述べる実施形態は、本発明の好適な具体例であるから、技術的に好ましい種々の限定が付されているが、本発明の範囲は、以下の説明において特に本発明を限定する旨の記載がない限り、これらの実施形態に限られるものではない。   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIG. 1 to FIG. 8 (the same parts are given the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

図1は本発明の面照明装置に係わる実施形態の斜視図である。面照明装置1は光源2、レンズ3、リフレクタ4、光拡散板5、光拡散シート6およびプリズムシート7から構成されており、面照明装置1を構成する各部材により以下に説明するような構造を有している。   FIG. 1 is a perspective view of an embodiment according to the surface illumination device of the present invention. The surface illumination device 1 includes a light source 2, a lens 3, a reflector 4, a light diffusion plate 5, a light diffusion sheet 6, and a prism sheet 7, and has a structure described below with each member constituting the surface illumination device 1. have.

光源2は熱陰極蛍光ランプからなる棒状光源であり、該棒状の光源2が複数本略平行に並設されている。なお、棒状光源としては従来、細径化の容易さ、長寿命、低コストといった理由から冷陰極蛍光ランプが使用されてきたが、本実施形態においては発光効率の高さから熱陰極蛍光ランプを採用した。勿論、冷陰極蛍光ランプを使用してもよい。   The light source 2 is a rod-shaped light source composed of a hot cathode fluorescent lamp, and a plurality of the rod-shaped light sources 2 are arranged substantially in parallel. Conventionally, cold cathode fluorescent lamps have been used as rod-shaped light sources for reasons of easy diameter reduction, long life, and low cost. However, in this embodiment, hot cathode fluorescent lamps are used because of their high luminous efficiency. Adopted. Of course, a cold cathode fluorescent lamp may be used.

光源2には、光源2に沿って延びる棒状のレンズ3が設けられている。レンズ3を該レンズ3の長手方向に垂直な面で切断したときの断面形状は図2に示すように、光源2の外周円8の曲率半径R1以上の曲率半径R2を有する円弧9と、円弧9の外側に位置し、円弧9の中心Pを通る直線を対称軸Aとする夫々円弧9の中心Pと反対方向に湾曲し且つ対称軸A上で繋がった2つの凸形状を有する曲線10と、円弧9と曲線10の夫々の端同士を結ぶ2つの直線11からなっている。なお、円弧9は後述する光入射面の断面形状、曲線10は光出射面の断面形状である。また、棒状の光源2と棒状のレンズ3は、光源2の外周円8の中心とレンズ3の円弧9の中心が同一位置で中心Pを共有するように位置すると共に、略同一の長さに設定されている。   The light source 2 is provided with a rod-shaped lens 3 extending along the light source 2. The cross-sectional shape when the lens 3 is cut by a plane perpendicular to the longitudinal direction of the lens 3 is an arc 9 having a radius of curvature R2 equal to or greater than the radius of curvature R1 of the outer circumferential circle 8 of the light source 2, as shown in FIG. A curve 10 having two convex shapes which are located outside the center 9 and are curved in opposite directions to the center P of the arc 9 with a straight line passing through the center P of the arc 9 as a symmetry axis A and connected on the symmetry axis A; , Consisting of two straight lines 11 connecting the ends of the arc 9 and the curve 10. In addition, the circular arc 9 is a cross-sectional shape of a light incident surface described later, and the curve 10 is a cross-sectional shape of a light emitting surface. The rod-shaped light source 2 and the rod-shaped lens 3 are positioned so that the center of the outer peripheral circle 8 of the light source 2 and the center of the arc 9 of the lens 3 share the center P at the same position, and have substantially the same length. Is set.

図1に戻って、夫々レンズ3が設けられた各光源2には該光源2の下方および側方を光源2の長手方向に沿って覆うように板状のリフレクタ4が配設され、リフレクタ4の少なくとも光源2に対向する側の面には光反射面12が形成されている。   Returning to FIG. 1, each light source 2 provided with a lens 3 is provided with a plate-like reflector 4 so as to cover the lower side and the side of the light source 2 along the longitudinal direction of the light source 2. A light reflecting surface 12 is formed on at least the surface facing the light source 2.

光源2の上方には、光線を360°の範囲内のいずれかの方向に拡散する光拡散板5および光拡散シート6が順次配設されており、光拡散シート6の上面側には更に、該光拡散シート6からの拡散光の向かう方向を制御するプリズムシート7が配設されている。   Above the light source 2, a light diffusing plate 5 and a light diffusing sheet 6 for sequentially diffusing light rays in any direction within a range of 360 ° are disposed, and further on the upper surface side of the light diffusing sheet 6, A prism sheet 7 for controlling the direction of diffused light from the light diffusion sheet 6 is disposed.

プリズムシート7は例えば、厚みが100μm程度であり、光源2の反対側の面が夫々90°の頂角を有す複数の連続する三角形からなるプリズム形状を呈している。   For example, the prism sheet 7 has a thickness of about 100 μm, and has a prism shape composed of a plurality of continuous triangles each having an apex angle of 90 ° on the opposite surface of the light source 2.

なお、光拡散シート6は光の拡散度を高めて面輝度分布の均一性を向上させ、プリズムシート7は集光性を高めて照明輝度を向上させる機能を有するものであり、場合によっては面照明装置に求められる光学仕様に基づいて削除される場合もある。反対に、プリズムシート7以外の光学フィルムを追加したり、あるいはプリズムシート7に替わる他の光学フィルムを用いる場合もある。   The light diffusion sheet 6 has a function of increasing the light diffusion degree to improve the uniformity of the surface luminance distribution, and the prism sheet 7 has a function of improving the light collecting property and improving the illumination luminance. In some cases, it may be deleted based on optical specifications required for the illumination device. Conversely, an optical film other than the prism sheet 7 may be added, or another optical film that replaces the prism sheet 7 may be used.

次に、レンズの設計方法について図3および図4を参照して詳細に説明する。まず、レンズ設計にあたって図3のようなモデルを設定する。   Next, a lens design method will be described in detail with reference to FIGS. First, when designing a lens, a model as shown in FIG. 3 is set.

光源2を線状光源とし、線状光源は棒状光源2の中心Pに位置するものとする。棒状レンズ3の光入射面16は、レンズ3を該レンズの長手方向に垂直な面で切断したときの断面形状が棒状光源2の中心Pを中心とする円弧9を呈し、断面円弧9を延長した円柱面の一部からなる。   Assume that the light source 2 is a linear light source, and the linear light source is located at the center P of the rod-shaped light source 2. The light incident surface 16 of the rod-shaped lens 3 has a cross-sectional shape when the lens 3 is cut by a surface perpendicular to the longitudinal direction of the lens, and exhibits an arc 9 centering on the center P of the rod-shaped light source 2, and extends the cross-sectional arc 9 It consists of a part of the cylindrical surface.

また、棒状光源2の中心Pを原点Qとし、原点Qを通って光拡散板5の光入射面13に平行な線をX軸、原点Qを通って光拡散板5の光入射面13に垂直な線をY軸とする。そして、Lは互いに隣接する光源2同士の間隔の半分の距離、L(θ)は棒状光源2の中心P(線状光源)からY軸に対してθの角度で出射した光線Bが光拡散板5の光入射面13に到達した位置のY軸からX方向の距離、Dは棒状光源2の中心PからY軸上の光入射面13までの距離、Θは棒状光源2の中心Pから出射した光線Bがレンズ3に入射する限界角度(Y軸に対する角度)、(X,Y)は棒状光源2の中心PからY軸に対してθの角度で出射した光線Bがレンズ3の光出射面14と交わる点の座標である。   Further, the center P of the rod-shaped light source 2 is defined as the origin Q, a line parallel to the light incident surface 13 of the light diffusing plate 5 through the origin Q is passed through the X axis and the origin Q to the light incident surface 13 of the light diffusing plate 5. Let the vertical line be the Y-axis. L is half the distance between the adjacent light sources 2, L (θ) is the light beam B emitted from the center P (linear light source) of the rod-like light source 2 at an angle θ with respect to the Y axis. The distance in the X direction from the Y axis at the position where the light incident surface 13 of the plate 5 is reached, D is the distance from the center P of the rod-shaped light source 2 to the light incident surface 13 on the Y axis, and Θ is from the center P of the rod-shaped light source 2. The limit angle (angle with respect to the Y axis) at which the emitted light beam B is incident on the lens 3 is (X, Y) is the light beam B emitted from the center P of the rod-shaped light source 2 at an angle θ with respect to the Y axis. It is the coordinates of the point that intersects the exit surface 14.

そして、棒状レンズ2の中心PからY軸に対して+Θ〜−Θの範囲内の角度で出射した光線Bが、光拡散板5の光入射面13の+L〜−Lの領域内に任意の照度分布を形成するようにレンズ3の光出射面14の断面曲線の軌跡(X,Y)を求める。   A light beam B emitted from the center P of the rod-shaped lens 2 at an angle within a range of + Θ to −Θ with respect to the Y axis is arbitrarily placed in a region of + L to −L of the light incident surface 13 of the light diffusion plate 5. The locus (X, Y) of the cross-sectional curve of the light exit surface 14 of the lens 3 is obtained so as to form an illuminance distribution.

なお、レンズ3の光出射面14の断面曲面は上述のように左右対称であるので、対称軸(Y軸)の一方Xの+方向(右側)の形状を求める。   Since the cross-sectional curved surface of the light emitting surface 14 of the lens 3 is bilaterally symmetric as described above, the shape of the + direction (right side) of one X of the symmetry axis (Y axis) is obtained.

図4はレンズの光出射面の断面曲線の具体的な求め方について示している。図中、αはレンズ3の光出射面14の座標(X,Y)の位置から出射する光線BがX軸となす角、θは棒状光源2の中心から出射してレンズ3の光出射面14の座標(X,Y)の位置に達する光線BがY軸となす角、φはレンズ3の光出射面14の座標(X,Y)の位置における接線がX軸となす角を夫々示している。   FIG. 4 shows a specific method for obtaining the cross-sectional curve of the light exit surface of the lens. In the figure, α is an angle formed by the light beam B emitted from the position of the coordinates (X, Y) of the light emitting surface 14 of the lens 3 and the X axis, and θ is emitted from the center of the rod-shaped light source 2 and is emitted from the lens 3. 14 represents the angle formed by the light beam B reaching the position of the coordinate (X, Y) of 14 with the Y axis, and φ represents the angle formed by the tangent at the position of the coordinate (X, Y) of the light exit surface 14 of the lens 3 with the X axis. ing.

そこで、レンズの屈折率をnとすると、座標(X,Y)における法線に対する入射角はθφとなり、出射角は(π/2)−αφとなり、以下の式が成り立つ。
n・sin(θφ)=sin{(π/2)-αφ} (1)
θ=tan -1(X/Y) (2)
φ=tan -1(-dX/dY) (3)
α=tan -1(D-Y)/{L(θ)-X} (4)
Therefore, when the refractive index of the lens is n, the incident angle with respect to the normal line at the coordinates (X, Y) is θ φ, and the emission angle is (π / 2) −α φ, and the following equation is established.
n · sin (θ φ) = sin {(π / 2) −α φ} (1)
θ = tan -1 (X / Y) (2)
φ = tan -1 (- dX / dY) (3)
α = tan -1 (DY) / {L (θ) -X} (4)

ここで、L(θ)は上述のようには棒状光源2の中心PからY軸に対してθの角度で出射した光線Bが光拡散板5の光入射面13のどの位置に到達したかを表す関数である。   Here, L (θ) is the position on the light incident surface 13 of the light diffusing plate 5 where the light beam B emitted from the center P of the rod-shaped light source 2 at an angle θ with respect to the Y-axis has reached as described above. Is a function that represents

なお、図3に示すように、レンズ3に限界角度Θで入射した光線Bがレンズ3の光出射面14から出射して光拡散板3の光入射面13のY軸からLの距離(レンズ3の光出射面14から出射された光線Bの光拡散板5の光入射面13におけるY軸からの最大到達距離)の位置に到達するものとすると、レンズ3の光出射面14から出射した光が光拡散板5の光入射面13に等照度で照射されるためには、レンズ3に入射する限界角度Θに対する実際にレンズ3に入射する角度θの比率と、光拡散板5の光入射面13に到達した光線Bの最大到達距離Lに対する実際に光拡散板5の光入射面13に到達した位置の比率との間に関連性をもたせればよい。   As shown in FIG. 3, the light beam B incident on the lens 3 at the limit angle Θ is emitted from the light exit surface 14 of the lens 3 and is a distance L from the Y axis of the light entrance surface 13 of the light diffusion plate 3 (lens If the light beam B emitted from the third light exit surface 14 reaches the position of the maximum arrival distance from the Y axis on the light incident surface 13 of the light diffusion plate 5, the light B exits from the light exit surface 14 of the lens 3. In order for light to irradiate the light incident surface 13 of the light diffusing plate 5 with equal illuminance, the ratio of the angle θ actually incident on the lens 3 to the limit angle Θ incident on the lens 3 and the light of the light diffusing plate 5 What is necessary is just to have relationship with the ratio of the position which actually reached | attained the light-incidence surface 13 of the light diffusing plate 5 with respect to the maximum reach | attainment distance L of the light ray B which reached | attained the incident surface 13.

従って、光拡散板5の光入射面13における到達光光線位置を、棒状光源2の中心Pから出射した光線Bの角度θを変数とした関数で表すと、
L(θ)=L・(θ/Θ) (5)
となる。この場合、L(θ)はリフレクタ4の光反射面12、光拡散板5、光拡散シート6、プリズムシート7など、夫々の光学特性によって様々に変化する。
Therefore, when the reaching light beam position on the light incident surface 13 of the light diffusing plate 5 is expressed by a function using the angle θ of the light beam B emitted from the center P of the rod-shaped light source 2 as a variable,
L (θ) = L ・ (θ / Θ) (5)
It becomes. In this case, L (θ) varies depending on the optical characteristics of the light reflecting surface 12, the light diffusing plate 5, the light diffusing sheet 6, the prism sheet 7, etc. of the reflector 4.

次に、上記式(1)を加法定理により展開すると、
n・sinθcosφ-n・cosθsinφ=sin{(π/2)-α}cosφ- cos{(π/2)-α}sinφ (6)
となり、式(6)の両辺をcosφで割ると
tanφ=[n・sinθ-sin{(π/2)-α}]/[n・cosθ-cos{(π/2)-α}] (7)
となる。
Next, when the above equation (1) is expanded by the addition theorem,
n · sinθcosφ n · cosθsinφ = sin {(π / 2) −α} cosφ cos {(π / 2) −α} sinφ (6)
When both sides of equation (6) are divided by cosφ
tanφ = [n · sin θ-sin {(π / 2) -α}] / [n · cos θ-cos {(π / 2) -α}] (7)
It becomes.

そこで、レンズ3の光出射面14の断面曲線の軌跡は、式(3)および式(7)より以下の微分方程式で表される。
dY/dX=tanφ=[sin{(π/2)-α}-n・sinθ]/[n・cosθ-cos{(π/2)-α}] (8)
Therefore, the locus of the cross-sectional curve of the light exit surface 14 of the lens 3 is expressed by the following differential equation from the equations (3) and (7).
dY / dX = tanφ = [sin {(π / 2) -α} -n · sinθ] / [n · cosθ-cos {(π / 2) -α}] (8)

但し、(8)式は実際には解析的に求めることができないので、差分近似によって求める。そこで、Xの刻み幅をΔとすると、
Xn+1=Xn+ΔX
Yn+1=[sin{(π/2)-α}-n・sinθ]/[n・cosθ-cos{(π/2)-α}]・ΔX+Yn (9)
となる。
However, since equation (8) cannot actually be obtained analytically, it is obtained by difference approximation. Therefore, if the step size of X is ΔX,
X n + 1 = X n + ΔX
Y n + 1 = [sin {(π / 2) -α} -n · sin θ] / [n · cos θ-cos {(π / 2) -α}] · Δ X + Y n (9)
It becomes.

線状光源の直上(Y軸上)のレンズ3の光出射面14の座標(X,Y)とし、順次式(9)を求める。そして、求めた座標(X,Y)、(X,Y)、・・・、(X,Y)を繋ぐことにより、レンズ3の光出射面14の断面曲線の形状を求めることができる。 Using the coordinates (X 0 , Y 0 ) of the light exit surface 14 of the lens 3 directly above the linear light source (on the Y axis), Equation (9) is obtained sequentially. Then, by connecting the obtained coordinates (X 0 , Y 0 ), (X 1 , Y 1 ),..., (X N , Y N ), the shape of the cross-sectional curve of the light exit surface 14 of the lens 3 is obtained. Can be sought.

図5および図6は、1つの線状光源から出射されてレンズ内を導光されてレンズの光出射面から出射された光が照射面に形成する照射分布をシミュレーションによって検証した条件および結果を示している。   5 and 6 show the conditions and results obtained by verifying the irradiation distribution formed on the irradiation surface by the light emitted from one linear light source and guided through the lens and emitted from the light emitting surface of the lens by simulation. Show.

シミュレーションの対象となるレンズを、図5のように夫々の光出射面の形状が異なる3種類のレンズ(a)〜(c)とした。図中、(a)のレンズ1は光出射面の形状が、
L(θ)=L(θ/Θ)
(b)のレンズ2は光出射面の形状が、
L(θ)=L√(θ/Θ)
(c)のレンズ3は光出射面の形状が、
L(θ)=L[3(θ/Θ)exp{-7(θ/Θ)}+(θ/Θ)]
の夫々の関数に基づくものである。
The lenses to be simulated were three types of lenses (a) to (c) having different light exit surfaces as shown in FIG. In the figure, the lens 1 in FIG.
L (θ) = L (θ / Θ)
In the lens 2 of (b), the shape of the light exit surface is
L (θ) = L√ (θ / Θ)
The lens 3 in (c) has a light exit surface shape.
L (θ) = L [3 (θ / Θ) exp {-7 (θ / Θ)} + (θ / Θ)]
It is based on each function.

その結果、図6で示されるように、レンズ1は−L〜+Lの範囲内に亘ってほぼ均一な照射分布を示しており、レンズ2は棒状光源の直上近傍の照度が低く、そこから遠ざかるにつれて照度が高くなり、距離Lの位置でほぼピークに達する。レンズ3は前記レンズ1とレンズ2の中間の照度分布を示している。   As a result, as shown in FIG. 6, the lens 1 exhibits a substantially uniform irradiation distribution over a range of −L to + L, and the lens 2 has a low illuminance immediately above the rod-shaped light source and moves away from it. As the illuminance increases, it reaches a peak at a distance L. The lens 3 shows an illuminance distribution intermediate between the lens 1 and the lens 2.

棒状光源から出射されてレンズ内を導光されて光拡散板の光入射面に到達した光は、光拡散板、光拡散シート、およびプリズムシートなどを導光されて面照明装置の光出射面から外部に出射されるが、面照明装置の光出射面における輝度分布は光拡散板、光拡散シート、およびプリズムシートなどの夫々が有する光学特性によって異なるものとなる。   The light emitted from the rod-shaped light source and guided through the lens to reach the light incident surface of the light diffusing plate is guided through the light diffusing plate, the light diffusing sheet, the prism sheet, etc., and the light emitting surface of the surface illumination device However, the luminance distribution on the light exit surface of the surface illumination device differs depending on the optical characteristics of the light diffusing plate, the light diffusing sheet, the prism sheet, and the like.

そのため、面照明装置の光出射面において所望の輝度分布を得るためには、光拡散板、光拡散シート、およびプリズムシートなどの光学特性に対応したレンズ設計(レンズの光出射面の形状設計)を行なう必要があるが、棒状光源から出射してレンズ内を導光された光が光拡散板の光入射面に形成する照度分布は、概ね図6に示すように棒状光源の直上近傍で低下し、X軸方向に広がるにつれて徐々に照度が高くなり、位置L、−Lの近傍で照度が最大となる。   Therefore, in order to obtain a desired luminance distribution on the light exit surface of the surface illumination device, the lens design corresponding to the optical characteristics of the light diffusing plate, the light diffusing sheet, the prism sheet, etc. (shape design of the light emitting surface of the lens) However, the illuminance distribution formed on the light incident surface of the light diffusing plate by the light emitted from the rod-shaped light source and guided through the lens is reduced in the vicinity of the portion directly above the rod-shaped light source as shown in FIG. However, the illuminance gradually increases as it spreads in the X-axis direction, and the illuminance becomes maximum in the vicinity of the positions L and -L.

従って、このような光学特性を備えたレンズを棒状光源に取付けることにより、面輝度分布の均一性の高い面照明装置を実現することが可能となる。   Therefore, by attaching a lens having such optical characteristics to a rod-shaped light source, it is possible to realize a surface illumination device with high uniformity of surface luminance distribution.

図7は本発明の面照明装置に係わる実施例の断面図、図8は実施例の輝度分布である。   FIG. 7 is a cross-sectional view of an embodiment of the surface illumination device according to the present invention, and FIG.

図7に示す実施例の面照明装置の基本構成は図1と同様であり、面照明装置1の光出射面15の寸法は、棒状光源2の長手方向(紙面の奥行き方向)が355mm、棒状光源2の長手方向に垂直な方向(X方向)が210mmである。光源2は管径がφ8mmの熱陰極蛍光ランプ(全光束642lm)を3本70mmの間隔で配設した。光拡散板5はRM803(住友化学株式会社製)、光拡散シート6はBS702(恵和株式会社製)、プリズムシート7はRBEF(住友スリ−エム株式会社製)を使用した。リフレクタ4の光源2と対向する側の面を酸化チタン微粒子を塗布した反射率を90%以上の光反射面12とした。レンズ3は材質がアクリルで、形状は図5(c)のレンズ3の形状とした。   The basic configuration of the surface illumination device of the embodiment shown in FIG. 7 is the same as that of FIG. 1, and the dimension of the light emitting surface 15 of the surface illumination device 1 is 355 mm in the longitudinal direction of the rod-shaped light source 2 (depth direction of the paper surface). The direction perpendicular to the longitudinal direction of the light source 2 (X direction) is 210 mm. As the light source 2, three hot cathode fluorescent lamps having a tube diameter of φ8 mm (total luminous flux of 642 lm) were arranged at intervals of 70 mm. The light diffusion plate 5 was RM803 (manufactured by Sumitomo Chemical Co., Ltd.), the light diffusion sheet 6 was BS702 (manufactured by Eiwa Co., Ltd.), and the prism sheet 7 was RBEF (manufactured by Sumitomo 3M Limited). The light reflecting surface 12 having a reflectance of 90% or more applied to the surface of the reflector 4 on the side facing the light source 2 was coated with titanium oxide fine particles. The material of the lens 3 is acrylic, and the shape thereof is the shape of the lens 3 in FIG.

図8は上記実施例の輝度分布と、実施例の構成からレンズを取り除いた比較例の輝度分布を、夫々の輝度分布の最大値で正規化したグラフである。グラフの表示範囲は、中央に位置する光源2を中心としたX方向の−35mm〜+35mmの範囲に亘っている。このグラフからわかるように、比較例は面照明装置の中央部近傍の輝度が他の部分に比べて高くなっているが、実施例は中央近傍の輝度が抑制されており、その分他の部分の輝度が改善されている。   FIG. 8 is a graph obtained by normalizing the luminance distribution of the above example and the luminance distribution of the comparative example in which the lens is removed from the configuration of the example with the maximum value of each luminance distribution. The display range of the graph covers a range of −35 mm to +35 mm in the X direction with the light source 2 located at the center as the center. As can be seen from this graph, the brightness in the vicinity of the central portion of the surface illumination device is higher than that in the other portions in the comparative example, but the brightness in the vicinity of the center is suppressed in the embodiment, and accordingly, the other portions. The brightness has been improved.

下記表1に実施例と比較例の輝度ムラの評価結果を示している。   Table 1 below shows the evaluation results of the luminance unevenness of the example and the comparative example.

Figure 0004452725
Figure 0004452725

表1のMAXはX方向の−35mm〜+35mmの範囲における輝度の最大値、MINは最小値、AVEは平均値である。また、(MAX−AVE)/AVE、および、(MIN−AVE)/AVEは共に輝度ムラの指標を示している。   MAX in Table 1 is the maximum luminance value in the range of −35 mm to +35 mm in the X direction, MIN is the minimum value, and AVE is the average value. Further, (MAX-AVE) / AVE and (MIN-AVE) / AVE both indicate indicators of luminance unevenness.

そこで、輝度ムラの指標となる(MAX−AVE)/AVE、および、(MIN−AVE)/AVEを実施例と比較例についてみてみると、(MAX−AVE)/AVEについては比較例が5.80%であるのに対し実施例は3.27%であり、(MIN−AVE)/AVEについては比較例が−5.91%であるのに対し実施例は−4.82%となっている。   Accordingly, when (MAX-AVE) / AVE and (MIN-AVE) / AVE, which are indicators of luminance unevenness, are examined in the example and the comparative example, the comparative example is 5. In contrast to 80%, the example is 3.27%, and for (MIN-AVE) / AVE, the comparative example is -5.91%, while the example is -4.82%. Yes.

従って、いずれの指標も実施例が比較例よりも輝度ムラが少ないことを示しており、レンズの光学的に優れた効果をもたらすことを示している。   Accordingly, any of the indexes indicates that the example has less luminance unevenness than the comparative example, and indicates that the optical effect of the lens is brought about.

以上説明したように、本発明の直下型の面照明装置は、従来の直下型面照明装置の問題点となっていた、光源の直上近傍の輝度と周囲の輝度との輝度勾配で生じる輝度ムラを改善し、輝度均斉度に優れた面照明装置を実現した。   As described above, the direct type surface illumination device according to the present invention has the problem of luminance unevenness caused by the luminance gradient between the luminance immediately above the light source and the surrounding luminance, which has been a problem of the conventional direct type surface illumination device. Improved surface brightness device with excellent brightness uniformity.

しかも、輝度ムラの改善方法は、光源にレンズを設けるだけの至って簡易な方法であり、これにより輝度ムラ改善に伴う製造コストの上昇を抑制することができる。   In addition, the method for improving luminance unevenness is a simple method in which a lens is simply provided on the light source, thereby suppressing an increase in manufacturing cost due to the luminance unevenness improvement.

また、レンズは、光源と組み合わせることによって均一な配光分布を形成するように設計されており、光源の並設間隔が広がったとしても光源にレンズを設けることによって面照明装置の厚みを変えることなく所望の輝度均斉度を得ることが可能となる。   In addition, the lens is designed to form a uniform light distribution by combining with the light source, and even if the interval between the light sources is widened, the thickness of the surface illumination device can be changed by providing the lens to the light source. Therefore, it is possible to obtain a desired luminance uniformity.

また、レンズは、該レンズの光出射面のみで光線を屈折させて配光分布を制御している。そのため、余計な迷光の発生がないために光の利用効率が高く、高輝度の面照明装置の実現に大いに寄与するものとなっている。   Further, the lens controls the light distribution by refracting light rays only on the light exit surface of the lens. For this reason, since no extra stray light is generated, the use efficiency of light is high, which greatly contributes to the realization of a high-luminance surface illumination device.

更に、光源に光束の多い熱陰極蛍ランプを使用することにより、上記本発明の効果が更に向上し、少ない光源で広範囲な領域を均一に照射する薄型で簡易な構造の面照明装置を提供することが可能になる。   Furthermore, by using a hot cathode fluorescent lamp with a large luminous flux as a light source, the effect of the present invention is further improved, and a surface illumination device having a thin and simple structure that uniformly irradiates a wide area with a small number of light sources is provided. It becomes possible.

本発明の面照明装置の斜視図である。It is a perspective view of the surface illumination device of the present invention. 本発明の面照明装置に係わる光源とレンズの関係を示す断面図である。It is sectional drawing which shows the relationship between the light source and lens concerning the surface illumination apparatus of this invention. 本発明の面照明装置の部分断面図である。It is a fragmentary sectional view of the surface illumination device of the present invention. 本発明の面照明装置に係わるレンズ設計の基になる参考図である。It is a reference figure used as the basis of lens design concerning the surface illumination device of the present invention. 本発明の面照明装置に係わるレンズの断面図である。It is sectional drawing of the lens concerning the surface illumination apparatus of this invention. 本発明の面照明装置に係わるレンズの照度分布を示すグラフである。It is a graph which shows the illumination intensity distribution of the lens concerning the surface lighting apparatus of this invention. 本発明の面照明装置に係わる実施例1の断面図である。It is sectional drawing of Example 1 concerning the surface illumination apparatus of this invention. 本発明の面照明装置に係わる実施例1の輝度分布を示すグラフである。It is a graph which shows the luminance distribution of Example 1 regarding the surface lighting apparatus of this invention. 従来の面照明装置の断面図である。It is sectional drawing of the conventional surface illumination apparatus. 従来の他の面照明装置の断面図である。It is sectional drawing of the other conventional surface illumination apparatus.

符号の説明Explanation of symbols

1 面照明装置
2 光源
3 レンズ
4 リフレクタ
5 光拡散板
6 光拡散シート
7 プリズムシート
8 外周円
9 円弧
10 曲線
11 直線
12 光反射面
13 光入射面
14 光出射面
15 光出射面
16 光入射面
DESCRIPTION OF SYMBOLS 1 Surface illumination device 2 Light source 3 Lens 4 Reflector 5 Light diffusing plate 6 Light diffusing sheet 7 Prism sheet 8 Peripheral circle 9 Arc 10 Curve 11 Straight line 12 Light reflecting surface 13 Light incident surface 14 Light emitting surface 15 Light emitting surface 16 Light incident surface

Claims (7)

単数または平行に並設された複数の棒状光源と、
前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、
前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、
前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、
前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、
前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L(θ/Θ)の関数に基づいて形成されていることを特徴とする面照明装置。
A plurality of rod-shaped light sources arranged in parallel or singularly;
A rod-shaped lens arranged in parallel and fixed in close contact with the respective rod-shaped light sources;
A reflector disposed so as to surround a part of the rod-shaped light source and the rod-shaped lens;
The rod-shaped lens has a cross-section when the rod-shaped lens is cut by a plane perpendicular to the longitudinal direction of the rod-shaped lens, an arc and a straight line that is located outside the arc and passes through the center of the arc as a symmetry axis. , respectively and the circular arc and the center of the curve with two convex led curved and on the symmetry axis in the opposite direction, Ri Do two straight lines connecting the ends to each other of each of said arcs and said curve,
A light distribution control unit comprising at least one of a light diffusing plate, a light diffusing sheet, and a prism sheet is provided above the rod-shaped light source, the rod-shaped lens, and the reflector,
The rod-shaped light source is a linear light source located at the center of the rod-shaped light source, and the light distribution control unit is substantially aligned with the axis of symmetry passing through the center of the rod-shaped light source. When positioned so as to be perpendicular, L is a distance that is half of the interval between the linear light sources adjacent to each other, θ is the angle of the light beam emitted from the linear light source with respect to the symmetry axis, and The angle of the light beam that exits and reaches the end of the cross-section arc of the rod-shaped lens with respect to the symmetry axis Θ is emitted from the linear light source at an angle θ with respect to the symmetry axis, and the cross-section of the rod-shaped lens A light beam incident on the rod-shaped lens from a light incident surface made of an arc, guided through the rod-shaped lens, and emitted from the light emitting surface formed of the convex cross-sectional curve of the rod-shaped lens is the light distribution control unit. On the linear light source side If the distance from the axis of symmetry to the position that reaches is L (θ), the cross-sectional convex curve of the rod-shaped lens is formed based on a function of L (θ) = L (θ / Θ) A surface illumination device.
単数または平行に並設された複数の棒状光源と、A plurality of rod-shaped light sources arranged in parallel or singularly;
前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、A rod-shaped lens arranged in parallel and fixed in close contact with the respective rod-shaped light sources;
前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、A reflector disposed so as to surround a part of the rod-shaped light source and the rod-shaped lens;
前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、The rod-shaped lens has a cross-section when the rod-shaped lens is cut by a plane perpendicular to the longitudinal direction of the rod-shaped lens, an arc and a straight line that is located outside the arc and passes through the center of the arc as a symmetry axis. A curve having two convex shapes each curved in a direction opposite to the center of the arc and connected on the axis of symmetry, and two straight lines connecting the ends of the arc and the curve,
前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、A light distribution control unit comprising at least one of a light diffusion plate, a light diffusion sheet, and a prism sheet is provided above the rod-shaped light source, the rod-shaped lens, and the reflector,
前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L√(θ/Θ)の関数に基づいて形成されていることを特徴とする面照明装置。The rod-shaped light source is a linear light source positioned at the center of the rod-shaped light source, and the light distribution control unit is substantially aligned with the axis of symmetry passing through the center of the rod-shaped light source. When positioned so as to be perpendicular, L is a distance that is half of the interval between the linear light sources adjacent to each other, θ is the angle of the light beam emitted from the linear light source with respect to the symmetry axis, and The angle of the light beam that exits and reaches the end of the cross-section arc of the rod-shaped lens with respect to the symmetry axis Θ is emitted from the linear light source at an angle θ with respect to the symmetry axis, and the cross-section of the rod-shaped lens A light beam incident on the rod-shaped lens from a light incident surface made of an arc, guided through the rod-shaped lens, and emitted from the light emitting surface formed of the convex cross-sectional curve of the rod-shaped lens is the light distribution control unit. On the linear light source side If the distance from the axis of symmetry at the position that reaches is L (θ), the cross-sectional convex curve of the rod-shaped lens is formed based on a function of L (θ) = L√ (θ / Θ). A surface illumination device.
単数または平行に並設された複数の棒状光源と、A plurality of rod-shaped light sources arranged in parallel or singularly;
前記夫々の棒状光源に略密着した状態で並設、固定された棒状レンズと、A rod-shaped lens arranged in parallel and fixed in close contact with the respective rod-shaped light sources;
前記棒状光源および前記棒状レンズの一部を囲むように配設されたリフレクタを備え、A reflector disposed so as to surround a part of the rod-shaped light source and the rod-shaped lens;
前記棒状レンズは、前記棒状レンズを該棒状レンズの長手方向に垂直な面で切断したときの断面が、円弧と、前記円弧の外側に位置し、前記円弧の中心を通る直線を対称軸とする、夫々前記円弧の中心と反対方向に湾曲し且つ前記対称軸上で繋がった2つの凸形状を有する曲線と、前記円弧および前記曲線の夫々の端同士を結ぶ2つの直線からなり、The rod-shaped lens has a cross-section when the rod-shaped lens is cut by a plane perpendicular to the longitudinal direction of the rod-shaped lens, an arc and a straight line that is located outside the arc and passes through the center of the arc as a symmetry axis. A curve having two convex shapes each curved in a direction opposite to the center of the arc and connected on the axis of symmetry, and two straight lines connecting the ends of the arc and the curve,
前記棒状光源、前記棒状レンズ、および前記リフレクタの上方に、光拡散板、光拡散シートおよびプリズムシートのうち少なくとも1つからなる配光制御ユニットを備え、A light distribution control unit comprising at least one of a light diffusing plate, a light diffusing sheet, and a prism sheet is provided above the rod-shaped light source, the rod-shaped lens, and the reflector,
前記棒状光源を該棒状光源の中心に位置する線状光源とすると共に前記配光制御ユニットを該配光制御ユニットの前記線状光源側の面が前記棒状光源の中心を通る前記対称軸に略垂直になるように位置させたときに、互いに隣接する前記線状光源同士の間隔の半分の距離をL、前記線状光源から出射した光線の前記対称軸に対する角度をθ、前記線状光源から出射して前記棒状レンズの前記断面円弧の端部に到達する光線の前記対称軸に対する角度をΘ、前記線状光源から前記対称軸に対してθの角度で出射し、前記棒状レンズの前記断面円弧からなる光入射面から前記棒状レンズに入射し、前記棒状レンズ内を導光されて前記棒状レンズの前記断面凸形状曲線からなる光出射面から出射した光線が、前記配光制御ユニットの前記線状光源側の面に到達する位置の前記対称軸からの距離をL(θ)とすると、前記棒状レンズの前記断面凸形状曲線はL(θ)=L[3(θ/Θ)exp{−7(θ/Θ)}+(θ/Θ)]の関数に基づいて形成されていることを特徴とする面照明装置。The rod-shaped light source is a linear light source located at the center of the rod-shaped light source, and the light distribution control unit is substantially aligned with the axis of symmetry passing through the center of the rod-shaped light source. When positioned so as to be perpendicular, L is a distance that is half of the interval between the linear light sources adjacent to each other, θ is the angle of the light beam emitted from the linear light source with respect to the symmetry axis, and The angle of the light beam that exits and reaches the end of the cross-section arc of the rod-shaped lens with respect to the symmetry axis Θ is emitted from the linear light source at an angle θ with respect to the symmetry axis, and the cross-section of the rod-shaped lens A light beam incident on the rod-shaped lens from a light incident surface made of an arc, guided through the rod-shaped lens, and emitted from the light emitting surface formed of the convex cross-sectional curve of the rod-shaped lens is the light distribution control unit. On the linear light source side L (θ) is the distance from the axis of symmetry at the position reaching the position L (θ) = L [3 (θ / Θ) exp {−7 (θ / Θ) )} + (Θ / Θ)] is formed based on the function.
前記棒状レンズは、該棒状レンズの前記円弧の中心が前記棒状光源の外周円の中心と略同一位置となるように前記棒状光源に並設、固定されていることを特徴とする請求項1から3のいずれか1項に記載の面照明装置。 The bar lens from claim 1, characterized in that the center of the circular arc of the rod-shaped lens arranged on the rod-shaped light source such that the center and the substantially the same position of the outer circumference of the rod-shaped light sources are fixed surface lighting device according to any one of 3. 前記棒状レンズは前記棒状光源と略同一の長さを有していることを特徴とする請求項1から4のいずれか1項に記載の面照明装置。 The bar lens surface lighting device according to any one of claims 1 to 4, characterized in that it has the rod-shaped light sources is substantially the same length. 前記棒状レンズが形成する照度分布は、前記夫々の棒状光源の直上近傍において低く、互いに隣接する前記棒状光源方向に向かうにつれて徐々に高くなり、互いに隣接する前記棒状光源同士の間隔の半分の位置の直上近傍において最高となり、最外側に位置する棒状光源の外側では一端上昇した後、急速に減衰することを特徴とする請求項1から5のいずれか1項に記載の面照明装置。 The illuminance distribution formed by the rod-shaped lens is low in the vicinity immediately above each of the rod-shaped light sources, gradually increases toward the rod-shaped light sources adjacent to each other, and is located at a position that is half the distance between the rod-shaped light sources adjacent to each other. 6. The surface illumination device according to claim 1 , wherein the surface illumination device is highest in the vicinity immediately above, and is rapidly attenuated after rising one end outside the rod-shaped light source located on the outermost side. 前記棒状光源は熱陰極蛍光ランプであることを特徴とする請求項1から6のいずれか1項に記載の面照明装置。 The rod-shaped light source surface lighting device according to any one of claims 1 to 6, characterized in that the hot cathode fluorescent lamp.
JP2007000532A 2007-01-05 2007-01-05 Surface lighting device Expired - Fee Related JP4452725B2 (en)

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