JP3568273B2

JP3568273B2 - Linear light source

Info

Publication number: JP3568273B2
Application number: JP10440795A
Authority: JP
Inventors: 正美保本; 達也本池; 正康 ▲よし▼浦
Original assignee: Tottori Sanyo Electric Co Ltd; Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1995-04-27
Filing date: 1995-04-27
Publication date: 2004-09-22
Anticipated expiration: 2019-09-22
Also published as: JPH08307607A

Description

【０００１】
【産業上の利用分野】
本発明は、複数の光源部を基板の長手方向に沿って直線状に配置した線状光源に関する。
【０００２】
【従来の技術】
ファクシミリ装置や複写機などの画像読取装置に用いられる線状光源は、一般に、基板上にＬＥＤチップからなる発光素子を直線状に配列し、この配列にそって棒状の集光レンズや反射枠を配置して構成している（特開平５−３０４３１８号公報、特開平２−９４６７３号公報、特開平４−１５１２６７号公報、実願昭６２−１１０３９４号（実開昭６４−１３７５０号）のマイクロフィルム等参照）。
【０００３】
【発明が解決しようとする課題】
上記従来の構成によれば、棒状の集光レンズを備えるので薄型化が図れず、受光ラインセンサと組み合わせた密着型イメ−ジセンサへの搭載が困難である。また、成形部品が多く、組立て後の調節作業も必要であるので、組立て作業性が悪い。
【０００４】
また、光源の全長にわたる照度分布は、中央部分で平坦性が得られるものの、端部分において照度が落ち込むので、例えば光源の全長が２３０ｍｍの場合の有効光源長（照度偏差値±１０％以内）が２１０ｍｍ程度となり、利用に適さない光源長さが２０ｍｍ程度生じてしまう。
【０００５】
また、棒状の集光レンズに替えてＬＥＤチップを直接覆う連続した透光性樹脂を設けることも考えられるが、熱ストレスによって透光性樹脂に反りが発生して照度分布に狂いが生じ易くなる。
【０００６】
そこで本発明は、上記の点を考慮して成されたもので、構成の簡素化、光源長に対する有効光源長の増大、熱ストレスによる影響排除を図ることを主な課題とする。
【０００８】
【課題を解決するための手段】
本発明の線状光源は、長尺基板と、該基板上に配置された発光素子とこれを覆う透光性樹脂とによって構成され前記基板の長手方向に沿って互いに離間して直線状に配置した複数の光源部とから成り、前記複数の光源部は、その透光性樹脂の最大厚みを各々略一定にするとともに、端の前記光源部の透光性樹脂の平面形状を、それよりも内に位置する前記光源部の透光性樹脂の平面形状よりも前記基板の長手方向の長さが短くなるようにすることによって、透光性樹脂の平面形状を端の前記光源部とそれよりも内に位置する前記光源部とで異ならせ、端の光源部の透光性樹脂の集光度をそれよりも内に位置する光源部の透光性樹脂の集光度よりも高めたことを特徴とする。
【０００９】
また、本発明の線状光源は、長尺基板と、該基板上に配置された発光素子とこれを覆う透光性樹脂とによって構成され前記基板の長手方向に沿って互いに離間して直線状に配置した複数の光源部とから成り、前記複数の光源部を、その透光性樹脂の最大厚みを各々略一定にするとともに、その透光性樹脂の平面が長軸が前記基板の長手方向である楕円形状を成して前記基板の略全長に亘って所定ピッチで配置された複数の楕円状光源部と、その透光性樹脂の平面が円形若しくは前記楕円形状よりも円形に近い長軸が前記基板の長手方向である楕円形状を成す円状光源部とで構成した線状光源であって、前記線状光源の端部に前記円状光源部を最も外側の前記楕円状光源部と所定のピッチを有して配置し、端の光源部の透光性樹脂の集光度をそれよりも内に位置する光源部の透光性樹脂の集光度よりも高めたことを特徴とする。
【００１０】
【作用】
本発明によれば、光源部を基板の長手方向に沿って互いに離間して配置したので、透光性樹脂を基板の長手方向に連ねた場合のような熱ストレスによる樹脂の反りを殆ど無くして照度のバラツキを低減することができる。
【００１１】
また、複数の光源部は、基板の端に位置する光源部を構成する樹脂の集光度を他の光源部を構成する樹脂の集光度よりも高めたので、光源端部における照度を発光素子を変更することなく容易に増加して有効光源長を長くすることができる。
【００１２】
また、複数の光源部は、その透光性樹脂の最大厚みを各々略一定にするとともに、その透光性樹脂の平面形状を端の光源部とそれよりも内に位置する光源部とで異ならせたので、樹脂の平面形状の変更のみで集光度を容易に変更することができ、光源端部における照度を発光素子を変更することなく容易に変更することができるとともに、光源部の厚みを薄くしかも略均一にできるので、光源の薄型化を実現することができる。
【００１３】
また、複数の光源部を、その透光性樹脂の平面が楕円形状を成す楕円状光源部と、その透光性樹脂の平面が円形若しくは前記楕円形状よりも円形に近い円形状を成す円状光源部とで構成し、光源の端に円状光源部を配置したので、光緩衝（光の重ね合わせ）作用による照度分布の平坦化を楕円状光源部によって行うことができ、光源部の配置ピッチを長くして光源部の少数化を実現することができる。さらに、透光性樹脂の平面形状を、照度ムラが少なくしかも樹脂の安定な形状を得やすい楕円若しくは円状に変更するので、樹脂成形を容易にかつ安定して行い、光学特性の均一化を図ることができる。
【００１４】
【実施例】
以下、本発明の実施例を図面を参照して説明する。図１に示すように、線状光源１は、ガラスエポキシ等の絶縁性を有する長尺の基板１０（全長２２７ｍｍ）上に複数の光源部２０（この実施例では４０個）を基板１０の長手方向に沿って直線状に配置して構成している。基板１０は、ガラスエポキシ等の絶縁性を有する基材によって構成され、その表面には、各光源部２０用の電極とこれらを配線接続するための銅箔等の導電性パターン（図示せず）が設けられているとともに、この導電性パターンの所定部分（発光素子配置部分やリード線接続部分等）を除く基板１０の表面全体を覆うように光反射性の良い例えば白色の絶縁膜（図示せず）を設けている。基板１０の裏側には、図２に示すように取付用の両面テープなど接着層３０を設けている。
【００１５】
各光源部２０は、図２に示すように、基板１０の表面に施された導電性パターン上に導電性接着剤（いずれも図示せず）を介して同一のＬＥＤチップ等からなる発光素子２１を配置し、ワイヤ−ボンドしたこの発光素子２１を覆うようにエポキシ系樹脂などの透光性を有する樹脂２２を凸レンズ状にモ−ルドして構成している。各光源部２０の発光素子２１は、ＧａＡｌＡｓ（赤色），ＧａＰ（黄緑色）その他から選ばれた１つのＬＥＤチップで構成しているが、多色光源化に対応すべく、各光源部２０にそれぞれ多色発光ＬＥＤチップを配置することもできるし、各光源部２０にそれぞれ同一発光色若しくは異なる発光色の複数個のＬＥＤチップを配置することもできるし、読み取り装置などのマルチカラー化に対応すべく、発光色の異なる２〜３種類（好ましくは３原色に相当する色から選択された発光色を有する）のＬＥＤチップを繰り返して光源部２０に順次配置することもできる。
【００１６】
複数の光源部２０は、基板１０の略全長に亘って例えば５．７３ｍｍのピッチで互いに離間して配置され、その平面形状が楕円形状を成す複数の楕円状光源部２０ａを備えているとともに、基板１０の両端に位置するように最も外側の楕円状光源部２０ａと例えば５．５ｍｍのピッチを有して配置され、その平面形状が円形状を成す円状光源部２０ｂとを備えている。基板１０表面の前記絶縁膜には、樹脂２２の成形時にこれら楕円状光源部２０ａや円状光源部２０ｂの樹脂平面形状を規定するための輪郭処理を施している。
【００１７】
各楕円状光源部２０ａは、光源部の数が少なくそのピッチが長い場合であっても、隣接光源部の光緩衝（光の重なり）を利用した照度分布の平坦化を実現するために、その長軸方向を基板１０の長手方向と同方向（長軸が基板長手方向と若干交差していてもよい）に配置し、隣接する楕円状光源部２０ａの光緩衝度が高められるように構成している。そのため、楕円状光源部２０ａを構成する樹脂２２ａは、図３に示すように、例えばその長軸の長さが４ｍｍ，短軸の長さが３．４ｍｍの平面楕円形とするとともに、最大厚みが１ｍｍ前後の凸レンズ形状に構成している。このように平面楕円形状とすることによって、楕円状光源部２０ａのピッチが若干長くても、有効光源（照射）領域の照度を規定の範囲に保つことができ、楕円状光源部２０ａの数を少なくすることができる。
【００１８】
前記円状光源部２０ｂは、光源（基板）端部における照度分布の低下を防止して有効光源長を長くするために設けられたもので、それを構成する樹脂２２ｂを、図４に示すように、例えばその直径が３．４ｍｍの平面円形とするとともに、最大厚みが１ｍｍ前後の凸レンズ形状に構成している。このように、樹脂２２ｂの最大厚みを略同じにしてその平面形状を楕円状光源部２０ａの樹脂２２ａよりも狭くしているので、発光素子２１から発せられる光量が同じ場合に、その光の集光度を楕円状光源部２０ａにおける場合よりも高めることができ、照度分布の低下が生じる光源端部の照度を増加させて照度分布が平坦な領域の長さを光源端部まで増加させ、光源全長に対する有効光源長の割合を大きくすることができる。なお、円状光源部２０ｂは、発光素子２１から発せられた光の集光度を楕円状光源部２０ａよりも高めることができればよく、樹脂２２ｂの平面形状を前記楕円状光源部２０ａの樹脂２２ａよりも円形に近い楕円平面形状（例えば、長軸の長さが３．５〜３．６ｍｍ，短軸の長さが３．４ｍｍの平面楕円形）とすることもできる。また、光の集光度を増加させるように樹脂の種類を変化させることもできるが、製造工程が複雑化するので同一の樹脂を用いてその平面形状や厚みなどを変化させることによって光集光度を変化させることが同一の製造工程を利用できる点で望ましい。特に、樹脂の厚みを略同じにしてその平面形状を変化させれば、光源の厚みを全範囲に亘って均一に薄くできるので、厚みを変化させる場合に比べて薄型化の点で好ましい。
【００１９】
上記のように、線状光源１は、光源部２０を構成する透光性樹脂を基板１０上に直接形成するので、その構成を簡素化することができるとともに、各光源部２０を離間配置しているので、樹脂２２の熱ストレスによる歪みや反りなどの変形が発生することがなく、照度分布の狂いを防止することができる。また，各光源部２０の厚みを約１ｍｍと極めて薄くかつ均一化できるので、線状光源１の薄型化を実現することができる。
【００２０】
上記の構成によって次の様な特性が得られた。まず、光源の断面方向に沿った光の拡がりを示す断面照度分布特性を図５に示す。この光学特性は、基板１０の長手方向と直交する断面に沿って基板１０の表面から８ｍｍの距離における照度分布を測定したものである。同図（ａ）は、上記断面が楕円状光源部２２の発光素子２１を通過する場合の特性であり、同図（ｂ）は、上記断面が楕円状光源部２２間を通過する場合の特性である。この特性図から明らかなように、楕円状光源部２２のピッチが多少長くても楕円状光源部２２の光緩衝作用によって光源部２２上と光源部２２間上とで同じような照度が得られていることがわかる。特に、８０％の照度が得られる長さ（幅）が両方とも５．６ｍｍと所定の値が得られたので、基板１０の装着精度が多少悪くても被照明部分に所定の照度を確実に与えることができる。
【００２１】
次に、光源（基板）の長手方向に沿った照度分布特性を図６に示す。この光学特性は、各光源部２０を通過するように基板１０の長手方向に沿って基板１０の表面から８ｍｍの距離の照度を測定し、この測定照度に基づいて求めた照度偏差を示している。この特性図から明らかなように、照度偏差±１０％以内の領域は光源のほぼ全長に亘り、２１９ｍｍを実現することができた。したがって、光源全長２２７ｍｍに対して有効光源長を２１９ｍｍとすることができ、光源長に対する有効光源長の割合を高めることができた。
【００２２】
【発明の効果】
本発明によれば、光源部を基板の長手方向に沿って互いに離間して配置したので、透光性樹脂を基板の長手方向に連ねた場合のような熱ストレスによる樹脂の反りを殆ど無くして照度のバラツキを低減することができる。
【００２３】
また、複数の光源部は、基板の端に位置する光源部を構成する樹脂の集光度を他の光源部を構成する樹脂の集光度よりも高めたので、光源端部における照度を発光素子を変更することなく容易に増加して有効光源長を長くすることができる。
【００２４】
また、複数の光源部は、その透光性樹脂の最大厚みを各々略一定にするとともに、その透光性樹脂の平面形状を端の光源部とそれよりも内に位置する光源部とで異ならせたので、樹脂の平面形状の変更のみで集光度を容易に変更することができ、光源端部における照度を発光素子を変更することなく容易に変更することができるとともに、光源部の厚みを薄くしかも略均一にできるので、光源の薄型化を実現することができる。
【００２５】
また、複数の光源部を、その透光性樹脂の平面が楕円形状を成す楕円状光源部と、その透光性樹脂の平面が円形若しくは前記楕円形状よりも円形に近い円形状を成す円状光源部とで構成し、光源の端に円状光源部を配置したので、光緩衝（光の重ね合わせ）作用による照度分布の平坦化を楕円状光源部によって行うことができ、光源部の配置ピッチを長くして光源部の少数化を実現することができる。さらに、透光性樹脂の平面形状を、照度ムラが少なくしかも樹脂の安定な形状を得やすい楕円若しくは円状に変更するので、樹脂成形を容易にかつ安定して行い、光学特性の均一化を図ることができる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す線状光源の斜視図である。
【図２】図１の要部拡大断面図である
【図３】楕円状光源部の構成例を示し、（ａ）は平面図、（ｂ）は断面図である。
【図４】円状光源部の構成例を示し、（ａ）は平面図、（ｂ）は断面図である。
【図５】光源の断面照度分布特性図を示し、（ａ）は光源部上、（ｂ）は光源部間上の分布特性図である。
【図６】光源の長手方向照度分布特性図である。
【符号の説明】
１線状光源
１０基板
２０光源部
２０ａ楕円状光源部
２０ｂ円状光源部
２１発光素子
２２透光性樹脂[0001]
[Industrial applications]
The present invention relates to a linear light source in which a plurality of light source units are linearly arranged along a longitudinal direction of a substrate.
[0002]
[Prior art]
Linear light sources used in image reading devices such as facsimile machines and copiers generally have light emitting elements made up of LED chips arranged linearly on a substrate, and a bar-shaped condenser lens or reflection frame is arranged along this arrangement. Japanese Patent Laid-Open Nos. Hei 5-304318, Hei 2-94673, Hei 4-151267, and Japanese Utility Model Application No. Sho 62-110394 (Japanese Utility Model Application Laid-Open No. 64-13750). See film etc.).
[0003]
[Problems to be solved by the invention]
According to the above-mentioned conventional configuration, since a bar-shaped condensing lens is provided, the thickness cannot be reduced, and it is difficult to mount the lens on a contact image sensor combined with a light receiving line sensor. Also, since there are many molded parts and adjustment work after assembly is necessary, the assembling workability is poor.
[0004]
In the illuminance distribution over the entire length of the light source, although flatness can be obtained at the center portion, the illuminance drops at the end portion. Therefore, for example, when the total length of the light source is 230 mm, the effective light source length (illuminance deviation value ± 10% or less) is reduced. As a result, the length of the light source becomes about 210 mm, which is not suitable for use.
[0005]
It is also conceivable to provide a continuous translucent resin that directly covers the LED chip in place of the rod-shaped condensing lens, but the translucent resin is warped due to thermal stress, and the illuminance distribution is likely to be deviated. .
[0006]
Therefore, the present invention has been made in consideration of the above points, and has as its main objects to simplify the configuration, increase the effective light source length with respect to the light source length, and eliminate the influence of thermal stress.
[0008]
[Means for Solving the Problems]
The linear light source according to the present invention includes a long substrate, a light emitting element disposed on the substrate, and a light-transmitting resin covering the long substrate, and is linearly spaced apart from each other along the longitudinal direction of the substrate. A plurality of light source portions, the plurality of light source portions, the maximum thickness of the light-transmitting resin is substantially constant, respectively, and the planar shape of the light-transmitting resin of the light source portion at the end, by than the planar shape of the translucent resin of the light source unit positioned to make the long side direction of the length of the substrate is reduced within it and the light source portion of the end of planar shape of the translucent resin Different from the light source portion located further inside, that the light-collecting degree of the light- transmitting resin of the light source part at the end is higher than the light-collecting degree of the light-transmitting resin of the light source part located inside. Features.
[0009]
Further, the linear light source of the present invention comprises a long substrate, a light emitting element disposed on the substrate, and a light-transmitting resin covering the same, and is linearly separated from each other along the longitudinal direction of the substrate. A plurality of light source sections arranged in the same direction, and the plurality of light source sections have substantially the same maximum thickness of the light-transmitting resin, and the long axis of the plane of the light-transmitting resin is the longitudinal direction of the substrate. A plurality of elliptical light source portions arranged in a predetermined pitch over substantially the entire length of the substrate, and a long axis whose plane of the translucent resin is circular or more circular than the elliptical shape. Is a linear light source comprising an elliptical circular light source portion that is the longitudinal direction of the substrate, the outermost elliptical light source portion the circular light source portion at the end of the linear light source. place a predetermined pitch, its the light collection of the translucent resin of the light source portion of the end Characterized in that higher than the degree of convergence of the light transmitting resin of a light source unit located on the inner than.
[0010]
[Action]
According to the present invention, since the light source units are arranged apart from each other along the longitudinal direction of the substrate, there is almost no warpage of the resin due to thermal stress as in the case of connecting the translucent resin in the longitudinal direction of the substrate. Variation in illuminance can be reduced.
[0011]
In addition, since the plurality of light sources have a higher light concentration of the resin constituting the light source located at the edge of the substrate than the light constituting of the other light source constituting the light source, the illuminance at the end of the light source is a light emitting element. It is possible to increase the effective light source length easily without changing it.
[0012]
In addition, the plurality of light source sections have substantially the same maximum thickness of the light-transmitting resin, and the light-transmitting resin has a different planar shape between the light source section at the end and the light source section located inside the light source section. The light intensity can be easily changed only by changing the planar shape of the resin, and the illuminance at the end of the light source can be easily changed without changing the light emitting element, and the thickness of the light source portion can be reduced. Since the light source can be made thin and substantially uniform, the thickness of the light source can be reduced.
[0013]
Further, the plurality of light source units may be an elliptical light source unit in which the plane of the translucent resin has an elliptical shape, and a circular shape in which the plane of the translucent resin has a circular shape or a circular shape closer to a circle than the elliptical shape. Since the light source unit and the circular light source unit are arranged at the end of the light source, the illuminance distribution can be flattened by the elliptical light source unit due to the light buffering (superposition of light) action. By increasing the pitch, the number of light source units can be reduced. Furthermore, the planar shape of the translucent resin is changed to an elliptical or circular shape with less unevenness in illuminance and easy to obtain a stable shape of the resin, so that resin molding can be performed easily and stably to make the optical characteristics uniform. Can be planned.
[0014]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a linear light source 1 has a plurality of light source units 20 (40 in this embodiment) on a long substrate 10 (total length of 227 mm) having insulating properties such as glass epoxy. They are arranged in a straight line along the direction. The substrate 10 is formed of an insulating base material such as glass epoxy, and has on its surface an electrode for each light source unit 20 and a conductive pattern (not shown) such as a copper foil for wiring and connecting these. And a light-reflecting, for example, white insulating film (not shown) so as to cover the entire surface of the substrate 10 except for predetermined portions of the conductive pattern (light emitting element arrangement portions, lead wire connection portions, etc.). Z). On the back side of the substrate 10, an adhesive layer 30 such as a double-sided tape for attachment is provided as shown in FIG.
[0015]
As shown in FIG. 2, each light source unit 20 includes a light emitting element 21 made of the same LED chip or the like via a conductive adhesive (neither is shown) on a conductive pattern provided on the surface of the substrate 10. And a light-transmitting resin 22 such as an epoxy resin is molded in a convex lens shape so as to cover the wire-bonded light emitting element 21. The light emitting element 21 of each light source unit 20 is composed of one LED chip selected from GaAlAs (red), GaP (yellow green) and others. A multicolor LED chip can be arranged for each, a plurality of LED chips of the same light emission color or different light emission colors can be arranged for each light source section 20, and it corresponds to a multicolor of a reading device or the like. To this end, two or three types of LED chips having different emission colors (preferably having emission colors selected from the colors corresponding to the three primary colors) may be repeatedly arranged in the light source unit 20 repeatedly.
[0016]
The plurality of light source units 20 are spaced apart from each other at a pitch of, for example, 5.73 mm over substantially the entire length of the substrate 10, and include a plurality of elliptical light source units 20a whose planar shapes are elliptical. An outermost elliptical light source unit 20a and a circular light source unit 20b having a pitch of, for example, 5.5 mm and having a circular planar shape are provided so as to be located at both ends of the substrate 10. The insulating film on the surface of the substrate 10 is subjected to contour processing for defining the resin planar shape of the elliptical light source portion 20a and the circular light source portion 20b when the resin 22 is molded.
[0017]
Even when the number of light source units is small and the pitch is long, each of the elliptical light source units 20a is designed to realize a flat illuminance distribution using light buffering (overlapping light) of adjacent light source units. The major axis direction is arranged in the same direction as the longitudinal direction of the substrate 10 (the major axis may slightly intersect the longitudinal direction of the substrate), so that the light buffering degree of the adjacent elliptical light source unit 20a is increased. ing. Therefore, as shown in FIG. 3, the resin 22a constituting the elliptical light source unit 20a has, for example, a planar elliptical shape having a major axis length of 4 mm and a minor axis length of 3.4 mm, and a maximum thickness. Has a convex lens shape of about 1 mm. With such a planar elliptical shape, the illuminance of the effective light source (irradiation) area can be kept within a specified range even if the pitch of the elliptical light source sections 20a is slightly longer, and the number of elliptical light source sections 20a can be reduced. Can be reduced.
[0018]
The circular light source section 20b is provided to prevent a decrease in the illuminance distribution at the end of the light source (substrate) and to increase the effective light source length. As shown in FIG. In addition, for example, it has a planar circular shape with a diameter of 3.4 mm and a maximum lens thickness of about 1 mm. As described above, since the maximum thickness of the resin 22b is substantially the same and the planar shape is narrower than the resin 22a of the elliptical light source unit 20a, when the light amount emitted from the light emitting element 21 is the same, the light collection The luminous intensity can be increased as compared with the case of the elliptical light source unit 20a, the illuminance at the light source end where the illuminance distribution is reduced is increased, the length of the region where the illuminance distribution is flat is increased to the light source end, and the light source total length Can be increased. Note that the circular light source unit 20b only needs to be able to increase the degree of condensing light emitted from the light emitting element 21 more than the elliptical light source unit 20a, and the planar shape of the resin 22b is higher than that of the resin 22a of the elliptical light source unit 20a. Can also be an elliptical planar shape that is nearly circular (for example, a planar elliptical shape having a major axis length of 3.5 to 3.6 mm and a minor axis length of 3.4 mm). In addition, the type of resin can be changed so as to increase the light condensing degree. However, since the manufacturing process is complicated, the light condensing degree is changed by changing the planar shape and the thickness of the same resin using the same resin. Variation is desirable in that the same manufacturing process can be used. In particular, when the thickness of the resin is made substantially the same and the planar shape thereof is changed, the thickness of the light source can be reduced uniformly over the entire range, which is preferable in terms of thinning as compared with the case where the thickness is changed.
[0019]
As described above, in the linear light source 1, the light-transmitting resin constituting the light source unit 20 is formed directly on the substrate 10, so that the configuration can be simplified and the light source units 20 are separately arranged. Therefore, deformation such as distortion or warpage due to thermal stress of the resin 22 does not occur, and it is possible to prevent the illuminance distribution from being disordered. Further, since the thickness of each light source unit 20 can be made extremely thin and uniform, about 1 mm, the linear light source 1 can be made thinner.
[0020]
The following characteristics were obtained by the above configuration. First, FIG. 5 shows a cross-sectional illuminance distribution characteristic indicating the spread of light along the cross-sectional direction of the light source. The optical characteristics are obtained by measuring the illuminance distribution at a distance of 8 mm from the surface of the substrate 10 along a cross section orthogonal to the longitudinal direction of the substrate 10. FIG. 6A shows the characteristics when the cross section passes through the light emitting element 21 of the elliptical light source unit 22, and FIG. 6B shows the characteristics when the cross section passes between the elliptical light source units 22. It is. As is clear from this characteristic diagram, even if the pitch of the elliptical light source unit 22 is slightly longer, the same illuminance can be obtained on the light source unit 22 and between the light source units 22 by the light buffering action of the elliptical light source unit 22. You can see that it is. In particular, since both the lengths (widths) at which the illuminance of 80% can be obtained are 5.6 mm, which is a predetermined value, even if the mounting accuracy of the substrate 10 is somewhat poor, the predetermined illuminance can be reliably applied to the illuminated portion. Can be given.
[0021]
Next, the illuminance distribution characteristics along the longitudinal direction of the light source (substrate) are shown in FIG. The optical characteristics indicate the illuminance deviation obtained by measuring the illuminance at a distance of 8 mm from the surface of the substrate 10 along the longitudinal direction of the substrate 10 so as to pass through each light source unit 20, and based on the measured illuminance. . As is clear from this characteristic diagram, the area within the illuminance deviation of ± 10% can be realized over almost the entire length of the light source and 219 mm. Therefore, the effective light source length could be 219 mm with respect to the total light source length of 227 mm, and the ratio of the effective light source length to the light source length could be increased.
[0022]
【The invention's effect】
According to the present invention, since the light source units are arranged apart from each other along the longitudinal direction of the substrate, there is almost no warpage of the resin due to thermal stress as in the case of connecting the translucent resin in the longitudinal direction of the substrate. Variation in illuminance can be reduced.
[0023]
In addition, since the plurality of light sources have a higher light concentration of the resin constituting the light source located at the edge of the substrate than the light constituting of the other light source constituting the light source, the illuminance at the end of the light source is a light emitting element. It is possible to increase the effective light source length easily without changing it.
[0024]
In addition, the plurality of light source sections have substantially the same maximum thickness of the light-transmitting resin, and the light-transmitting resin has a different planar shape between the light source section at the end and the light source section located inside the light source section. The light intensity can be easily changed only by changing the planar shape of the resin, and the illuminance at the end of the light source can be easily changed without changing the light emitting element, and the thickness of the light source portion can be reduced. Since the light source can be made thin and substantially uniform, the thickness of the light source can be reduced.
[0025]
Further, the plurality of light source units may be an elliptical light source unit in which the plane of the translucent resin has an elliptical shape, and a circular shape in which the plane of the translucent resin has a circular shape or a circular shape closer to a circle than the elliptical shape. Since the light source unit and the circular light source unit are arranged at the ends of the light source, the illuminance distribution can be flattened by the elliptical light source unit due to the light buffering (overlapping light) action. By increasing the pitch, the number of light source units can be reduced. Furthermore, the planar shape of the translucent resin is changed to an elliptical or circular shape with less unevenness in illuminance and easy to obtain a stable shape of the resin, so that resin molding can be performed easily and stably to make the optical characteristics uniform. Can be planned.
[Brief description of the drawings]
FIG. 1 is a perspective view of a linear light source showing one embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1; FIG. 3 shows a configuration example of an elliptical light source unit, where (a) is a plan view and (b) is a cross-sectional view.
4A and 4B show a configuration example of a circular light source unit, where FIG. 4A is a plan view and FIG. 4B is a cross-sectional view.
FIGS. 5A and 5B are cross-sectional illuminance distribution characteristic diagrams of a light source, wherein FIG. 5A is a distribution characteristic diagram on a light source unit and FIG.
FIG. 6 is a diagram showing a longitudinal illuminance distribution characteristic of a light source.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Linear light source 10 Substrate 20 Light source part 20a Elliptical light source part 20b Circular light source part 21 Light emitting element 22 Translucent resin

Claims

It is composed of a long substrate, a plurality of light source units which are constituted by a light emitting element disposed on the substrate and a translucent resin covering the same and which are linearly arranged apart from each other along the longitudinal direction of the substrate. The plurality of light source units, while making the maximum thickness of the light-transmitting resin substantially constant, and the planar shape of the light-transmitting resin of the light source unit at the end, of the light source unit located thereunder. by so long side direction of the length of the substrate is shorter than the planar shape of the translucent resin, the light source located on the inner and the light source unit of the end of planar shape of the translucent resin than A linear light source characterized in that the light condensing degree of the light transmissive resin of the light source part at the end is made higher than the light condensing degree of the light transmissive resin of the light source part located inside.

It is composed of a long substrate, a plurality of light source units which are constituted by a light emitting element disposed on the substrate and a translucent resin covering the same and which are linearly arranged apart from each other along the longitudinal direction of the substrate. The plurality of light source sections, the maximum thickness of the light-transmitting resin is substantially constant, and the plane of the light-transmitting resin has an elliptical shape whose major axis is the longitudinal direction of the substrate. A plurality of elliptical light sources arranged at a predetermined pitch over substantially the entire length of the substrate, and an elliptical shape in which the major axis of the light-transmitting resin is circular or a longer axis closer to a circle than the elliptical shape is the longitudinal direction of the substrate. A linear light source configured with a circular light source unit forming a circular light source unit, wherein the circular light source unit is disposed at an end of the linear light source with a predetermined pitch with the outermost elliptical light source unit, light source unit located on the inner than the condensing degree of the translucent resin of the light source portion of the end Linear light source, characterized in that it higher than the degree of convergence of the light-transmitting resin.