JP2006185628A - Backlight - Google Patents

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JP2006185628A
JP2006185628A JP2004374898A JP2004374898A JP2006185628A JP 2006185628 A JP2006185628 A JP 2006185628A JP 2004374898 A JP2004374898 A JP 2004374898A JP 2004374898 A JP2004374898 A JP 2004374898A JP 2006185628 A JP2006185628 A JP 2006185628A
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light
reflecting
light guide
led
light emitting
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JP2004374898A
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Japanese (ja)
Inventor
Yoji Kawasaki
要二 川崎
Yuji Azuma
祐二 我妻
Ryuji Tsuchiya
竜二 土屋
Hirokazu Nakamura
浩積 中村
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Toshiba Lighting and Technology Corp
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Harison Toshiba Lighting Corp
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Priority to JP2004374898A priority Critical patent/JP2006185628A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight in which brightness unevenness of light emitted from a light emitting face can be adjusted easily without inducing reduction of brightness. <P>SOLUTION: On a reflecting face 31b of a light guide plate 31, a light reflecting recess part 50 is arranged tapered toward the light emitting face 31a side having a flat inclined face 50a composed of a flat face to reflect an incident light from an LED 10 to the light emitting face 31a side, and having a curved inclined face 50b composed of a curved face of partially circular-arc continuously installed at this flat inclined face 50a. The respective light reflecting recess parts 50 are formed relatively the larger when the more separated against the LED 10, and formed relatively the larger when the more separated from the light guide path of the LED 10. Furthermore, the light reflecting recess part 50 positioned in a region in which a plurality of light guide paths of the LEDs 10 are overlapped is formed relatively smaller than that on the light guide path of the single LED 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、複数の発光ダイオード等の発光素子を光源として用いたバックライトに関する。   The present invention relates to a backlight using a light emitting element such as a plurality of light emitting diodes as a light source.

近年、複数の発光ダイオード等の発光素子を、光源として導光板の入射面に配列したバックライトが提案されている。この種のバックライトでは、各発光素子が点発光する点光源であるため、光源に対して垂直な方向（すなわち、奥行き方向）のみならず、光源に対して水平な方向（すなわち、光源の配列方向）にも輝度ムラが発生し易い。   In recent years, backlights in which light emitting elements such as a plurality of light emitting diodes are arranged as light sources on the incident surface of a light guide plate have been proposed. In this type of backlight, since each light emitting element is a point light source that emits point light, not only a direction perpendicular to the light source (that is, the depth direction) but also a direction that is horizontal to the light source (that is, the arrangement of the light sources) (Direction), luminance unevenness is likely to occur.

そこで、例えば特許文献１には、導光板の反射面上に、ドット印刷等によって導光板の反射面上に円形の光反射パターン或いは円錐形の光反射凹部（以下、これらを総称して光反射部と称す）を配列し、各光反射部の面積率を、各光源に対して垂直方向に離間する程大きく形成し、且つ、各光源に対して水平方向に離間する程大きく形成する技術が開示されている。
特開２００１−４３７１４公報 Therefore, for example, in Patent Document 1, a circular light reflection pattern or a conical light reflection concave portion (hereinafter collectively referred to as light reflection on the reflection surface of the light guide plate by dot printing or the like on the reflection surface of the light guide plate. And the area ratio of each light reflecting portion is formed so as to increase in the vertical direction with respect to each light source, and to increase in the horizontal direction with respect to each light source. It is disclosed.
JP 2001-43714 A

しかしながら、上述の特許文献１に開示された技術では、円形或いは円錐形とすることによって面積率の異なる光反射部を反射面上に容易に形成することが可能であるものの、これらの光反射部は光源からの光を拡散反射させるものであるため（すなわち、導光板の発光面側に全反射させるものではないため）、その反射光の制御が困難である。   However, in the technique disclosed in Patent Document 1 described above, although it is possible to easily form light reflecting portions having different area ratios on the reflecting surface by using a circular or conical shape, these light reflecting portions Since the light from the light source is diffusely reflected (that is, not totally reflected on the light emitting surface side of the light guide plate), it is difficult to control the reflected light.

しかも、上述のように光反射部で乱反射した光は、発光面から出光するまでの間に不要な反射を繰り返すため、光のエネルギーロスを生じやすく、発光面から出光する光の輝度を低下させる虞がある。   In addition, as described above, the light irregularly reflected by the light reflecting portion repeats unnecessary reflections until it is emitted from the light emitting surface, so that it easily causes light energy loss and lowers the luminance of the light emitted from the light emitting surface. There is a fear.

本発明は、輝度の低下を招くことなく、発光面から出光する光の輝度ムラを容易に調整することのできるバックライトを提供することを目的とする。   An object of the present invention is to provide a backlight capable of easily adjusting luminance unevenness of light emitted from a light emitting surface without causing a decrease in luminance.

本発明は、発光面と反射面とが互いに対向する平面矩形形状の導光板の少なくとも一端面に設定した入射面に沿って、点発光する光源を複数配列したバックライトであって、前記導光板は、前記点光源からの入射光を前記発光面側に反射する平坦面よりなる平坦傾斜面と、当該平坦傾斜面に連設する部分円弧状の湾曲面よりなる湾曲傾斜面と、を有する前記発光面側へ向けて先細の光反射凹部を前記反射面上に複数具備し、前記各光反射凹部を前記光源に対して離間する程相対的に大きく形成し、且つ、前記光源の導光路から外れたもの程相対的に大きく形成したことを特徴とする。   The present invention is a backlight in which a plurality of light sources that emit point light are arranged along at least one end face of a planar rectangular light guide plate in which a light emitting surface and a reflective surface face each other, Includes a flat inclined surface formed of a flat surface that reflects incident light from the point light source toward the light emitting surface, and a curved inclined surface formed of a partially arcuate curved surface provided continuously to the flat inclined surface. A plurality of light reflecting concave portions tapered toward the light emitting surface are provided on the reflecting surface, each light reflecting concave portion is formed relatively large as being separated from the light source, and from the light guide path of the light source. It is characterized in that it is formed relatively larger as it comes off.

本発明のバックライトによれば、輝度の低下を招くことなく、発光面から出光する光の輝度ムラを容易に調整することができる。   According to the backlight of the present invention, it is possible to easily adjust the luminance unevenness of light emitted from the light emitting surface without causing a decrease in luminance.

以下、図面を参照して本発明の実施形態を説明する。図面は本発明の一実施形態に係わり、図１はバックライトの分解斜視図、図２はバックライトの要部断面図、図３は導光板の反射面に配列される代表的な各光反射凹部を示す説明図、図４は導光板を図３のＹ１−Ｙ１線、Ｙｏ−Ｙｏ線、及び、Ｙｐ−Ｙｐ線に相当する各線に沿ってそれぞれ示す要部断面図、図５は光反射凹部の形成方法の一例を示す部分拡大図、図６は光反射凹部の拡大図である。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is an exploded perspective view of a backlight, FIG. 2 is a cross-sectional view of the main part of the backlight, and FIG. 3 is a representative light reflection arranged on the reflection surface of the light guide plate. FIG. 4 is an explanatory view showing the concave portion, FIG. 4 is a cross-sectional view of the main part showing the light guide plate along each line corresponding to the Y1-Y1 line, Yo-Yo line, and Yp-Yp line in FIG. 3, and FIG. FIG. 6 is a partially enlarged view showing an example of a method for forming the recess, and FIG. 6 is an enlarged view of the light reflecting recess.

図１，２において符号１は液晶テレビ等に好適なバックライトを示し、このバックライト１は、上面が開口した扁平な略箱形形状のケース２を有する。ケース２は、例えば射出成型による樹脂成型品で構成され、背面板２ａの内側一側寄りには隔壁３が立設している。そして、この隔壁３は、ケース２の内部を、ＬＥＤ収容室５と、導光室６とに画成している。   1 and 2, reference numeral 1 denotes a backlight suitable for a liquid crystal television or the like. The backlight 1 has a flat, substantially box-shaped case 2 having an upper surface opened. The case 2 is made of, for example, a resin molded product by injection molding, and a partition wall 3 stands on the inner side of the back plate 2a. The partition 3 defines the inside of the case 2 into an LED storage chamber 5 and a light guide chamber 6.

ＬＥＤ収容室５は、例えば、点発光する複数（例えば、３個）の表面実装型の発光ダイオード（以下、ＬＥＤと称す）１０を光源として収容する。具体的には、ＬＥＤ収容室５の長手方向両端部には互いに対向する一対の基板保持溝５ａが凹設しており、これら基板保持溝５ａは、各ＬＥＤ１０をＬＥＤ基板１１上に等間隔毎に実装した光源ユニット２０をＬＥＤ収容室５内に保持する。そして、図１，２に示すように、ＬＥＤ収容室５内に収容保持された各ＬＥＤ１０は、隔壁３に凹設された連通溝７を介して、その発光面を導光室６に露呈する。   The LED storage chamber 5 stores, for example, a plurality of (for example, three) surface-mounted light-emitting diodes (hereinafter referred to as LEDs) 10 that emit point light as light sources. Specifically, a pair of substrate holding grooves 5a facing each other are recessed at both ends in the longitudinal direction of the LED storage chamber 5, and these substrate holding grooves 5a are arranged on the LED substrate 11 at regular intervals. The light source unit 20 mounted on the LED storage chamber 5 is held in the LED storage chamber 5. As shown in FIGS. 1 and 2, each LED 10 housed and held in the LED housing chamber 5 exposes its light emitting surface to the light guide chamber 6 through a communication groove 7 recessed in the partition wall 3. .

ここで、本実施形態において、各ＬＥＤ１０は、所定色温度の白色光を発光する白色ＬＥＤである。このようなＬＥＤ１０は、例えば、Ｒ、Ｇ、Ｂの３つの発光体を１つのパッケージにして構成してもよく、また、例えば、単色のＬＥＤに蛍光物質を塗布して出射光を白色光に変換するよう構成してもよい。   Here, in the present embodiment, each LED 10 is a white LED that emits white light having a predetermined color temperature. Such an LED 10 may be configured, for example, by using three light emitters of R, G, and B in one package. For example, a single-color LED is coated with a fluorescent material to convert emitted light into white light. You may comprise so that it may convert.

導光室６は、例えば、一方の面に反射面３０ａを有する平面矩形形状の反射シート３０と、発光面３１ａと反射面３１ｂとが互いに平行に対向する平面矩形形状の導光板３１と、一方の面に拡散シート３３を貼着した平面矩形形状のレンズシート３２と、を背面板２ａ側から順に積層して収容する。さらに、導光室６は、一方の面に反射面３４ａを有する短冊状の反射シート３４を、各ＬＥＤ１０に対向する側面板２ｂに沿って収容する。   The light guide chamber 6 includes, for example, a planar rectangular reflective sheet 30 having a reflective surface 30a on one surface, a planar rectangular light guide plate 31 in which a light emitting surface 31a and a reflective surface 31b face each other in parallel, A flat rectangular lens sheet 32 having a diffusion sheet 33 attached to the surface thereof is stacked and accommodated in order from the back plate 2a side. Furthermore, the light guide chamber 6 accommodates a strip-shaped reflection sheet 34 having a reflection surface 34 a on one surface along the side plate 2 b facing each LED 10.

なお、図中符号３６は、ケース２に冠設するベゼルである。このベゼル３６には、レンズシート３２に貼着された拡散シート３３を外部に露呈するための矩形の開口部３６ａが開口しており、図２に示すように、ベゼル３６は、ケース２に冠設することにより、ＬＥＤ収容室５の上面開口部を閉塞し、さらに、レンズシート３２（及び、拡散シート３３）の縁辺部をケース２との間に挟持する。   Reference numeral 36 in the figure denotes a bezel that is provided on the case 2. The bezel 36 has a rectangular opening 36a for exposing the diffusion sheet 33 attached to the lens sheet 32 to the outside. As shown in FIG. By providing, the upper surface opening of the LED storage chamber 5 is closed, and the edge of the lens sheet 32 (and the diffusion sheet 33) is sandwiched between the case 2 and the case 2.

図２〜４に示すように、各ＬＥＤ１０に対向する導光板３１の一端面は各ＬＥＤ１０からの出射光を入射する入射面３１ｃとして設定されており、この入射面３１ｃから入射した光を反射して発光面３１ａに導く反射面３１ｂ上には、複数の光反射凹部５０が凹設している。   As shown in FIGS. 2 to 4, one end surface of the light guide plate 31 facing each LED 10 is set as an incident surface 31 c on which light emitted from each LED 10 is incident, and reflects light incident from the incident surface 31 c. A plurality of light reflecting recesses 50 are formed on the reflecting surface 31b leading to the light emitting surface 31a.

図６に示すように、各光反射凹部５０は、発光面３１ａに向けて先細の半月状凹部（ムーンカット）であり、具体的には、各光反射凹部５０は、反射面３１ｂに対して所定角度（例えば、４５°）で傾斜する平坦面よりなる平坦傾斜面５０ａと、当該平坦傾斜面５０ａに連設し、反射面３１ｂに対して所定角度（例えば、４５°）で傾斜する部分円弧状の湾曲面よりなる湾曲傾斜面５０ｂとを有する。   As shown in FIG. 6, each light reflecting recess 50 is a half-moon-shaped recess (moon cut) that is tapered toward the light emitting surface 31a. Specifically, each light reflecting recess 50 is located on the reflecting surface 31b. A flat inclined surface 50a composed of a flat surface inclined at a predetermined angle (for example, 45 °), and a partial circle connected to the flat inclined surface 50a and inclined at a predetermined angle (for example, 45 °) with respect to the reflecting surface 31b. A curved inclined surface 50b made of an arcuate curved surface.

ここで、光反射凹部５０は、例えば図５に示すように、円柱状のエンドミル５１等の工具を用いて容易に削成することが可能である。すなわち、各光反射凹部５０は、導光板３１の反射面３１ｂに対し、エンドミル５１を所定角度α（例えば、α＝４５°）傾斜させた状態で押し当て、その先端面の一部を接触させることなく反射面３１ｂを削ることにより、形成することができる。   Here, for example, as shown in FIG. 5, the light reflecting recess 50 can be easily cut using a tool such as a cylindrical end mill 51. That is, each light reflecting recess 50 presses the end mill 51 against the reflecting surface 31b of the light guide plate 31 in a state where the end mill 51 is inclined at a predetermined angle α (for example, α = 45 °), and contacts a part of the tip surface thereof. The reflective surface 31b can be formed without shaving.

各光反射凹部５０は、例えば図３に示すように、平坦傾斜面５０ａが入射面３１ｃにそれぞれ正対した状態で、反射面３１ｂ上にマトリクス状に配列している。   For example, as shown in FIG. 3, each light reflecting recess 50 is arranged in a matrix on the reflecting surface 31b with the flat inclined surface 50a facing the entrance surface 31c.

さらに、各光反射凹部５０は、発光面３１ａから均斉度の高い光を出射すべく、その大きさが反射面３１ｂ上での配設位置に応じて異なっている。具体的に説明すると、原則として、各光反射凹部５０は、ＬＥＤ１０に対して離間するもの程、相対的に大きく形成されている。ここで、ＬＥＤ１０に対しての離間とは、ＬＥＤ１０に対する垂直方向への離間、及び、ＬＥＤ１０に対する水平方向への離間を含む。また、各光反射凹部５０は、ＬＥＤ１０に対して等しく離間するものであっても、各ＬＥＤ１０から導光板３１に入射する光の導光路（図３中において一点鎖線で囲まれた領域）から外れたもの程、相対的に大きく形成されている。さらに、ＬＥＤ１０に対して等しく離間するものであっても、各光反射凹部５０は、各ＬＥＤ１０の導光路が重なる領域に位置するものが、単一のＬＥＤ１０の導光路上のものよりも相対的に小さく形成されている。   Furthermore, the size of each light reflecting recess 50 varies depending on the position on the reflecting surface 31b in order to emit light with high uniformity from the light emitting surface 31a. Specifically, in principle, each light reflecting recess 50 is formed to be relatively large as it is separated from the LED 10. Here, the separation with respect to the LED 10 includes a separation in the vertical direction with respect to the LED 10 and a separation in the horizontal direction with respect to the LED 10. Moreover, even if each light reflection recessed part 50 is equally spaced with respect to LED10, it will remove | deviate from the light guide path (area | region enclosed with the dashed-dotted line in FIG. 3) of the light which injects into the light-guide plate 31 from each LED10. It is relatively large. Further, even if the light reflection recesses 50 are equally spaced from the LED 10, the light reflecting recesses 50 are positioned in the region where the light guide paths of the respective LEDs 10 overlap with each other rather than those on the light guide path of the single LED 10. It is formed small.

すなわち、例えば、図３に示すＸ−Ｙ座標系（但し、Ｘ１＜Ｘｌ＜Ｘｍ＜Ｘｎ，Ｙ１＜Ｙｏ＜Ｙｐ＝Ｙmax）において、反射面３１ｂ上の座標（Ｘ１，Ｙ１）に位置する光反射凹部５０は、最も小さく形成されている。   That is, for example, in the XY coordinate system shown in FIG. 3 (where X1 <Xl <Xm <Xn, Y1 <Yo <Yp = Ymax), the light reflection located at the coordinates (X1, Y1) on the reflecting surface 31b. The recess 50 is formed to be the smallest.

また、座標（Ｘ１，Ｙ１）に位置する光反射凹部５０よりも、座標（Ｘ１，Ｙｌ）に位置する光反射凹部５０が相対的に大きく形成され、さらに、座標（Ｘ１，Ｙｍ）に位置する光反射凹部５０が相対的に大きく形成され、さらに、座標（Ｘ１，Ｙｎ）に位置する光反射凹部５０が相対的に大きく形成されている。   Further, the light reflecting recess 50 positioned at the coordinates (X1, Yl) is formed relatively larger than the light reflecting recess 50 positioned at the coordinates (X1, Y1), and further positioned at the coordinates (X1, Ym). The light reflecting recess 50 is formed relatively large, and the light reflecting recess 50 located at the coordinates (X1, Yn) is formed relatively large.

また、ＬＥＤ１０の導光路から最も外れた座標（Ｘ１，Ｙｐ）に位置する光反射凹部５０は最も大きく形成されており、この光反射凹部５０よりも、座標（Ｘｌ，Ｙｐ）に位置する光反射凹部５０が相対的に小さく形成され、さらに、座標（Ｘｍ，Ｙｐ）に位置する光反射凹部５０が相対的に小さく形成されている。   Further, the light reflection concave portion 50 located at the coordinates (X1, Yp) farthest from the light guide path of the LED 10 is formed to be the largest, and the light reflection located at the coordinates (X1, Yp) is larger than the light reflection concave portion 50. The recess 50 is formed to be relatively small, and the light reflection recess 50 located at the coordinates (Xm, Yp) is formed to be relatively small.

また、２つのＬＥＤ１０の導光路が重なる領域の座標（Ｘｎ，Ｙｐ）に位置する光反射凹部５０は、ＬＥＤ１０から同等の距離だけ離間する光反射凹部５０よりも相対的に小さく形成されている。特に、この座標（Ｘｎ，Ｙｐ）に位置する光反射凹部５０は、座標（Ｘｍ，Ｙｐ）に位置する光反射凹部５０よりもＬＥＤ１０から離間するにも拘わらず、相対的に小さく形成されている。また、この座標（Ｘｎ，Ｙｐ）に位置する光反射凹部５０は、座標（Ｘｎ，Ｙｏ）に位置する光反射凹部５０よりもＬＥＤ１０から離間するにも拘わらず、相対的に小さく形成されている。   Further, the light reflecting recess 50 located at the coordinates (Xn, Yp) of the region where the light guide paths of the two LEDs 10 overlap is formed to be relatively smaller than the light reflecting recess 50 that is separated from the LED 10 by an equal distance. In particular, the light reflecting recess 50 positioned at the coordinates (Xn, Yp) is formed to be relatively smaller than the light reflecting recess 50 positioned at the coordinates (Xm, Yp), despite being separated from the LED 10. . Further, the light reflecting recess 50 located at the coordinates (Xn, Yp) is formed to be relatively smaller than the light reflecting recess 50 positioned at the coordinates (Xn, Yo), despite being separated from the LED 10. .

ここで、各光反射凹部５０の大きさは、同一径の円柱状のエンドミル５１を用いて、その削成深さｔ（図５参照）によって容易に規定することが可能である。なお、各光反射凹部５０の大きさは、上述の各原則に従ってそれぞれ設定されるものであるが、実験やシミュレーション等の結果に基づいて適宜補正してもよいことは勿論である。   Here, the size of each of the light reflecting recesses 50 can be easily defined by the cutting depth t (see FIG. 5) using a cylindrical end mill 51 having the same diameter. The size of each light reflecting recess 50 is set according to the above-described principles, but it is needless to say that the size may be appropriately corrected based on the results of experiments and simulations.

次に、各光反射凹部５０のより具体的な一例について、図４を参照して説明する。図４（ａ）〜（ｃ）は、例えば、直径０．８ｍｍのエンドミル５１を用いて削成深さｔ＝０．０８ｍｍ〜０．４ｍｍの範囲内で形成した各光反射凹部５０が、反射面３１ｂ上において、ＬＥＤ１０の水平方向（図３のＸ軸方向）に１．５ｍｍピッチ、垂直方向（図３のＹ軸方向）に１ｍｍピッチでマトリクス状に配列された対角長が約８インチの導光板３１を示す。   Next, a more specific example of each light reflecting recess 50 will be described with reference to FIG. 4 (a) to 4 (c) show, for example, that each light reflecting recess 50 formed by using an end mill 51 having a diameter of 0.8 mm within a cutting depth t = 0.08 mm to 0.4 mm is reflected. On the surface 31b, the diagonal length of the LED 10 arranged in a matrix at a pitch of 1.5 mm in the horizontal direction (X-axis direction in FIG. 3) and 1 mm pitch in the vertical direction (Y-axis direction in FIG. 3) is about 8 inches. The light guide plate 31 is shown.

図４（ａ）は、図３のＹ１−Ｙ１線に相当する位置での要部断面図であり、同図において、領域Ａ〜Ｃは何れも単一のＬＥＤ１０の導光路上の領域に相当する。従って、各光反射凹部５０は、入射面３１ｃに最近のものが最も小さく（深さｔ＝０．０８ｍｍ）、入射面３１ｃから離間するにつれて段階的に等比で大きくなっている。   4A is a cross-sectional view of the main part at a position corresponding to the Y1-Y1 line in FIG. 3, and in this figure, the areas A to C all correspond to areas on the light guide path of the single LED 10. To do. Accordingly, each of the light reflecting recesses 50 is the smallest on the incident surface 31c (depth t = 0.08 mm), and gradually increases in proportion as the distance from the incident surface 31c increases.

図４（ｂ）は、図３のＹｏ−Ｙｏ線に相当する位置での要部断面図であり、同図において、領域ＡはＬＥＤ１０の導光部から外れた領域に相当し、領域Ｂ，Ｃは単一のＬＥＤ１０の導光路上の領域に相当する。従って、領域Ａにおいて、各光反射凹部５０は、入射面３１ｃから離間するにつれて段階的に等比で小さくなっている。また、領域Ｂにおいて、入射面３１ｃに最も近い光反射凹部５０は、入射面３１ｃから最も離間する領域Ａの光反射凹部５０よりも相対的に小さく、且つ、領域Ｂ，Ｃにおいて、各光反射凹部５０は、入射面３１ｃから離間するにつれて段階的に等比で大きくなっている。   4B is a cross-sectional view of a main part at a position corresponding to the Yo-Yo line in FIG. 3, in which the region A corresponds to a region removed from the light guide portion of the LED 10, and the regions B, C corresponds to a region on the light guide path of the single LED 10. Accordingly, in the region A, each light reflecting recess 50 is gradually reduced in an equal ratio as the distance from the incident surface 31c increases. In the region B, the light reflecting recess 50 closest to the incident surface 31c is relatively smaller than the light reflecting recess 50 in the region A farthest from the incident surface 31c, and each of the light reflecting recesses 50 in the regions B and C is reflected. The concave portion 50 increases in a step-wise manner at an equal ratio as the distance from the incident surface 31c increases.

図４（ｃ）は、図３のＹｐ−Ｙｐ線に相当する位置での要部断面図であり、同図において、領域Ａ，ＢはＬＥＤ１０の導光路から外れた領域に相当し、領域Ｃは２つのＬＥＤ１０の導光路が重なる領域に相当する。また、領域Ａにおいて、入射面３１ｃに最も近い光反射凹部５０は、ＬＥＤ１０の導光部から最も外れた遠方に位置する。従って、領域Ａ，Ｂにおいて、各光反射凹部５０は、入射面３１ｃに最近のものが最も大きく（深さｔ＝０．４ｍｍ）、入射面３１ｃから離間するにつれて段階的に等比で小さくなっている。また、領域Ｃにおいて、入射面３１ｃに最も近い光反射凹部５０は、入射面３１ｃから最も離間する領域Ｂの光反射凹部５０よりも相対的に小さく、各光反射凹部５０は、入射面３１ｃから離間するにつれて段階的に大きくなっている。   FIG. 4C is a cross-sectional view of the main part at a position corresponding to the Yp-Yp line in FIG. 3. In FIG. 4, regions A and B correspond to regions out of the light guide path of the LED 10, and region C Corresponds to a region where the light guide paths of the two LEDs 10 overlap. In the region A, the light reflecting recess 50 closest to the incident surface 31 c is located farthest away from the light guide of the LED 10. Accordingly, in the regions A and B, the light reflecting recesses 50 are the largest on the incident surface 31c (depth t = 0.4 mm), and gradually decrease in proportion as the distance from the incident surface 31c increases. ing. In the region C, the light reflecting recess 50 closest to the incident surface 31c is relatively smaller than the light reflecting recess 50 in the region B farthest from the incident surface 31c, and each light reflecting recess 50 is separated from the incident surface 31c. Increasing in steps as the distance increases.

このような構成において、各ＬＥＤ１０から導光板３１に入射された光は、そのほとんどが各光反射凹部５０の平坦傾斜面５０ａによって発光面３１ａ側に全反射する（図４（ａ）〜（ｃ）参照）。また、平坦傾斜面５０ａで反射されずに反射シート３４に到達し、当該反射シート３４の反射面３４ａで反射した入射光の一部（戻り光）も、各光反射凹部５０の湾曲傾斜面５０ｂで発光面３１ａ側に無駄なく反射する。   In such a configuration, most of the light incident on the light guide plate 31 from each LED 10 is totally reflected on the light emitting surface 31a side by the flat inclined surface 50a of each light reflecting recess 50 (FIGS. 4A to 4C). )reference). Further, a part of the incident light (return light) that reaches the reflection sheet 34 without being reflected by the flat inclined surface 50 a and is reflected by the reflection surface 34 a of the reflection sheet 34 is also the curved inclined surface 50 b of each light reflecting recess 50. Thus, the light is reflected to the light emitting surface 31a side without waste.

このような実施形態によれば、導光板３１の反射面３１ｂに形成する各光反射凹部５０を、入射面３１ｃに正対する平坦面よりなる平坦傾斜面５０ａと、この平坦傾斜面５０ａに連設する部分円弧状の湾曲面よりなる湾曲傾斜面５０ｂとを有する発光面３１ａ側に先細の凹部で構成し、各ＬＥＤ１０から導光板３１への入射光のほとんどを平坦傾斜面５０ａによって発光面３１ａ側に全反射させることにより、導光板３１に入射した光が発光面３１ａから出光するまでの間に不要な反射を繰り返すことを低減することができる。従って、入射光のエネルギーロスを低減することができ、発光面３１ａから出光する光の輝度を格段に向上させることができる。   According to such an embodiment, the light reflecting recesses 50 formed on the reflecting surface 31b of the light guide plate 31 are connected to the flat inclined surface 50a, which is a flat surface facing the incident surface 31c, and the flat inclined surface 50a. The light-emitting surface 31a having a curved inclined surface 50b made of a partially arcuate curved surface is formed with a tapered recess, and most of the incident light from each LED 10 to the light guide plate 31 is formed on the light-emitting surface 31a side by the flat inclined surface 50a. By totally reflecting the light, it is possible to reduce repetition of unnecessary reflection until the light incident on the light guide plate 31 is emitted from the light emitting surface 31a. Therefore, the energy loss of incident light can be reduced, and the luminance of light emitted from the light emitting surface 31a can be significantly improved.

また、平坦傾斜面５０ａはＬＥＤ１０からの入射光を全反射させるものであるため、各平坦傾斜面５０ａの面積比の設定により反射面３１ｂ上の各部で発光面３１ａ側に反射させる光量を容易に制御することができ、発光面３１ａから出向する光の輝度ムラを容易に調整することができる。すなわち、各光反射凹部５０を、各ＬＥＤ１０に対して離間する程相対的に大きく形成し、且つ、各ＬＥＤ１０の導光路から外れたもの程相対的に大きく形成することにより、均斉度の高い光を発光面３１ａから出光させることができる。   Further, since the flat inclined surface 50a totally reflects the incident light from the LED 10, the amount of light reflected on the light emitting surface 31a side by each part on the reflecting surface 31b can be easily set by setting the area ratio of each flat inclined surface 50a. It is possible to control the brightness unevenness of the light emitted from the light emitting surface 31a. That is, each light reflecting recess 50 is formed to be relatively large as it is separated from each LED 10, and the light reflecting recess 50 is formed to be relatively large as it is separated from the light guide path of each LED 10. Can be emitted from the light emitting surface 31a.

さらに、導光板３１内において、各ＬＥＤ１０の導光路が重なる領域に位置する各光反射凹部５０を、単一のＬＥＤ１０の導光路上のものよりも相対的に小さく形成することにより、より均斉度の高い光を発光面３１ａから出光させることができる。   Furthermore, in the light guide plate 31, each light reflecting recess 50 located in a region where the light guide paths of the respective LEDs 10 overlap is formed to be relatively smaller than that on the light guide path of the single LED 10, so that the degree of uniformity is further increased. High light can be emitted from the light emitting surface 31a.

また、各光反射凹部５０を同一径の円柱状のエンドミル５１によって削成し、各光反射凹部５０の大きさをエンドミル５１による削成深さで規定することにより、平坦傾斜面５０ａの面積比を容易に制御することができる。特に、大きな平坦傾斜面５０ａを必要とする領域においては、エンドミル５１による削成深さが深く、平坦傾斜面５０ａを導光板３１内のより深い位置まで臨ませることができるので、入射光をより効果的に発光面３１ａ側に反射させることができる。   Further, each light reflecting recess 50 is cut by a cylindrical end mill 51 having the same diameter, and the size of each light reflecting recess 50 is defined by the cutting depth by the end mill 51, whereby the area ratio of the flat inclined surface 50a. Can be easily controlled. In particular, in a region that requires a large flat inclined surface 50a, the cutting depth by the end mill 51 is deep, and the flat inclined surface 50a can be brought to a deeper position in the light guide plate 31, so that incident light is more It can be effectively reflected to the light emitting surface 31a side.

なお、上述の実施形態においては、反射面上に各光反射凹部を格子状に配列した一例について説明したが、本発明はこれに限定されるものではなく、例えば、反射面上に各光反射凹部を千鳥状に配列してもよい。   In the above-described embodiment, an example in which the light reflecting recesses are arranged in a lattice shape on the reflecting surface has been described. However, the present invention is not limited to this, and for example, each light reflecting on the reflecting surface. The recesses may be arranged in a staggered pattern.

また、上述の実施形態においては、導光板の一端面に入射面を設定し、この単一の入射面に沿ってＬＥＤを配列した一例について説明したが、本発明はこれに限定されるものではなく、導光板の複数の端面に入射面を設定し、各入射面に沿ってＬＥＤをそれぞれ配列してもよいことは勿論である。この場合、反射面上には、各入射面にそれぞれ対応した指向性を有する各光反射凹部（すなわち、各入射面毎にそれぞれ正対する各光反射凹部）が形成される。   In the above-described embodiment, an example in which an incident surface is set on one end surface of the light guide plate and LEDs are arranged along the single incident surface has been described. However, the present invention is not limited to this. Of course, incident surfaces may be set on a plurality of end surfaces of the light guide plate, and LEDs may be arranged along the respective incident surfaces. In this case, each light reflecting recess having directivity corresponding to each incident surface is formed on the reflecting surface (that is, each light reflecting recess facing each incident surface).

また、上述の実施形態においては、円柱状のエンドミルを用いて反射面上に光反射凹部を直接的に削成した一例について説明したが、本発明はこれに限定されるものではなく、例えば、予めエンドミルで光反射凹部を削成した導光板を用いて金型を作成し、当該金型を用いた射出成型等によって導光板を成型することで反射面上に光反射凹部を形成してもよい。勿論、このように金型を介して反射面上に光反射凹部を形成することも、エンドミルを用いて反射面上に光反射凹部を削成するという概念に含まれるものである。   Moreover, in the above-described embodiment, an example in which the light reflecting concave portion is directly cut on the reflecting surface using a cylindrical end mill has been described, but the present invention is not limited thereto, for example, Even if the light reflection recess is formed on the reflection surface by creating a mold using the light guide plate in which the light reflection recess has been cut in advance by an end mill, and molding the light guide plate by injection molding using the mold. Good. Of course, the formation of the light reflecting recesses on the reflecting surface through the mold as described above is also included in the concept of cutting the light reflecting recesses on the reflecting surface using an end mill.

また、上述の実施形態においては、光源としてＬＥＤを採用した一例について説明したが、本発明はこれに限定されるものではなく、点発光する他の発光素子を光源として用いてもよいことは勿論である。   In the above-described embodiment, an example in which an LED is used as a light source has been described. However, the present invention is not limited thereto, and other light emitting elements that emit point light may be used as a light source. It is.

バックライトの分解斜視図Exploded perspective view of backlight バックライトの要部断面図Cross section of the main part of the backlight 導光板の反射面に配列される代表的な各光反射凹部を示す説明図Explanatory drawing which shows each typical light reflection recessed part arranged in the reflective surface of a light-guide plate 導光板を図３のＹ１−Ｙ１線、Ｙｏ−Ｙｏ線、及び、Ｙｐ−Ｙｐ線に相当する各線に沿ってそれぞれ示す要部断面図FIG. 3 is a cross-sectional view of the principal part showing the light guide plate along lines corresponding to the Y1-Y1 line, the Yo-Yo line, and the Yp-Yp line in FIG. 光反射凹部の形成方法の一例を示す部分拡大図Partial enlarged view showing an example of a method of forming a light reflecting recess 光反射凹部の拡大図Enlarged view of light reflecting recess

符号の説明Explanation of symbols

１…バックライト、１０…発光ダイオード（光源）、３１…導光板、３１ａ…発光面、３１ｂ…反射面、３１ｃ…入射面、５０…光反射凹部、５０ａ…平坦傾斜面、５０ｂ…湾曲傾斜面、５１…エンドミル（工具）
代理人 弁理士 伊 藤 進 DESCRIPTION OF SYMBOLS 1 ... Backlight, 10 ... Light emitting diode (light source), 31 ... Light guide plate, 31a ... Light emission surface, 31b ... Reflection surface, 31c ... Incident surface, 50 ... Light reflection recessed part, 50a ... Flat inclined surface, 50b ... Curved inclined surface 51 ... End mill (tool)
Agent Patent Attorney Susumu Ito

Claims (3)

発光面と反射面とが互いに対向する平面矩形形状の導光板の少なくとも一端面に設定した入射面に沿って、点発光する光源を複数配列したバックライトであって、
前記導光板は、前記点光源からの入射光を前記発光面側に反射する平坦面よりなる平坦傾斜面と、当該平坦傾斜面に連設する部分円弧状の湾曲面よりなる湾曲傾斜面と、を有する前記発光面側へ向けて先細の光反射凹部を前記反射面上に複数具備し、
前記各光反射凹部を前記光源に対して離間する程相対的に大きく形成し、且つ、前記光源の導光路から外れたもの程相対的に大きく形成したことを特徴とするバックライト。 A backlight in which a plurality of light sources emitting point light are arranged along an incident surface set to at least one end surface of a planar rectangular light guide plate in which a light emitting surface and a reflective surface are opposed to each other,
The light guide plate includes a flat inclined surface formed of a flat surface that reflects incident light from the point light source toward the light emitting surface, a curved inclined surface formed of a partially arcuate curved surface connected to the flat inclined surface, and A plurality of tapered light reflecting recesses on the reflecting surface toward the light emitting surface side,
The backlight is characterized in that each of the light reflecting concave portions is formed to be relatively large as it is separated from the light source, and the light reflecting recess is formed to be relatively large as it is separated from the light guide path of the light source. 複数の前記光源の導光路が重なる領域に位置する前記各光反射凹部を、単一の前記光源の導光路上のものよりも相対的に小さく形成したことを特徴とする請求項１記載のバックライト。   2. The back according to claim 1, wherein each of the light reflection concave portions located in a region where the light guide paths of the plurality of light sources overlap is formed to be relatively smaller than one on the light guide path of the single light source. Light. 前記各光反射凹部は、設定角度傾斜させた同一径の円柱状の工具によって前記反射面上に削成したものであって、
前記各光反射凹部の大きさを、前記エンドミルによる削成深さで規定したことを特徴とする請求項１または請求項２記載のバックライト。 Each of the light reflecting recesses is formed on the reflecting surface by a cylindrical tool having the same diameter inclined at a set angle,
3. The backlight according to claim 1, wherein the size of each of the light reflecting recesses is defined by a cutting depth by the end mill.
JP2004374898A 2004-12-24 2004-12-24 Backlight Abandoned JP2006185628A (en)

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US7611274B2 (en) 2006-08-22 2009-11-03 Chunghwa Picture Tubes, Ltd. Light-source fixing structure for backlight module
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CN108333663A (en) * 2017-01-20 2018-07-27 中华映管股份有限公司 The backlight module of light guide plate and its manufacturing method and application light guide plate
CN110364515A (en) * 2018-03-26 2019-10-22 日亚化学工业株式会社 The manufacturing method and light emitting module of light emitting module
CN115793133A (en) * 2023-02-09 2023-03-14 苏州天禄光科技股份有限公司 Side-in light guide plate with obliquely-cut cylindrical mesh points and backlight module

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