JP3985231B2 - Surface lighting device - Google Patents

Surface lighting device Download PDF

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JP3985231B2
JP3985231B2 JP2004065707A JP2004065707A JP3985231B2 JP 3985231 B2 JP3985231 B2 JP 3985231B2 JP 2004065707 A JP2004065707 A JP 2004065707A JP 2004065707 A JP2004065707 A JP 2004065707A JP 3985231 B2 JP3985231 B2 JP 3985231B2
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light
guide plate
light guide
light source
adhesive layer
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JP2005259374A (en
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直行 寺田
利知 鈴木
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Minebea Co Ltd
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本発明は、液晶表示装置等の照明手段として用いられる面状照明装置に関し、特に点状光源を使用したサイドライト型の面状照明装置に関する。   The present invention relates to a planar illumination device used as illumination means such as a liquid crystal display device, and more particularly to a sidelight type planar illumination device using a point light source.

従来、パーソナルコンピュータや携帯電話等の電子装置の表示デバイスとして液晶表示装置が広く使用されている。液晶は、ブラウン管等とは異なり自発光型の表示素子ではないため、たとえば透過型の液晶表示装置では、その液晶パネルに対して光を照射する照明手段が必須であり、外光を利用する反射型および半透過型の液晶表示装置でも、暗所での使用を可能にするために補助的な照明手段を備えている場合が多い。導光板と導光板の側方に配置された光源とを主要な構成要素とするサイドライト型の面状照明装置は、薄型化が容易であるという利点を有するため、このような液晶表示装置の照明手段として好適に使用されるものであり、その光源としては、線状光源である冷陰極管等が使用されてきた。しかし、近年、白色発光ダイオード（ＬＥＤ）の高性能化に伴い、さらなる小型・薄型化および低消費電力化を図るため、点状光源である白色ＬＥＤを光源とする面状照明装置が増加している。   Conventionally, liquid crystal display devices have been widely used as display devices for electronic devices such as personal computers and mobile phones. Since a liquid crystal is not a self-luminous display element unlike a cathode ray tube or the like, for example, in a transmissive liquid crystal display device, illumination means for irradiating light to the liquid crystal panel is indispensable, and reflection using external light is required. In many cases, the liquid crystal display device of the type and the transflective type is also provided with auxiliary illumination means to enable use in a dark place. A sidelight type planar illumination device having a light guide plate and a light source disposed on the side of the light guide plate as main components has an advantage that it can be easily thinned. It is suitably used as an illuminating means, and a cold cathode tube or the like that is a linear light source has been used as the light source. However, in recent years, with the improvement in performance of white light emitting diodes (LEDs), in order to further reduce the size and thickness and reduce power consumption, planar lighting devices using white LEDs as point light sources as light sources have increased. Yes.

図５（ａ）は、このようなサイドライト型の面状照明装置の要部を示す平面図であり、図５（ｂ）は、そのＡ−Ａ線断面図である。図５（ａ）において、面状照明装置１００は、導光板１０１と点状光源１０２とを備え、点状光源１０２は、フレキシブルプリント基板（ＦＰＣ）１０５上に実装されて導光板１０１の側方に配置されている。ここで、導光板１０１は、たとえばメタクリル樹脂やポリカーボネート樹脂を射出成形してなる透明部材であり、点状光源１０２は白色ＬＥＤである。また、導光板１０１の一主面１０１ｂとＦＰＣ１０５との間には、両面粘着テープ等の粘着層１０６が介在し、それによってＦＰＣ１０５は導光板１０１に固着されている。   Fig.5 (a) is a top view which shows the principal part of such a sidelight type planar illuminating device, FIG.5 (b) is the AA sectional view taken on the line. In FIG. 5A, the planar illumination device 100 includes a light guide plate 101 and a point light source 102. The point light source 102 is mounted on a flexible printed circuit board (FPC) 105 so as to be lateral to the light guide plate 101. Are arranged. Here, the light guide plate 101 is a transparent member formed by injection molding of, for example, methacrylic resin or polycarbonate resin, and the point light source 102 is a white LED. In addition, an adhesive layer 106 such as a double-sided adhesive tape is interposed between one main surface 101 b of the light guide plate 101 and the FPC 105, whereby the FPC 105 is fixed to the light guide plate 101.

このような面状照明装置１００は、点状光源１０２からの出射光を入光面１０１ｃから導光板１０１の内部へと入射させ、入射光が一方の主面１０１ａと他方の主面１０１ｂとの間で反射を繰返して導光板１０１内を伝播する過程でその一部を光出射面（たとえば主面１０１ａ）から出射させ、液晶パネルを照射するものである。したがって、面状照明装置１００の十分な輝度を確保するためには、まず点状光源１０２からの出射光の利用効率を高めることが重要である。この点に関し、上述した面状照明装置１００は、ＦＰＣ１０５が導光板１０１に固着されているため、点状光源１０２の入光面１０１ｃに対する位置ずれが小さい点で有利である一方、次のような問題を有している。   Such a planar illumination device 100 causes the light emitted from the point light source 102 to enter the inside of the light guide plate 101 from the light incident surface 101c, and the incident light is incident between the one main surface 101a and the other main surface 101b. In the process of repeatedly reflecting between them and propagating through the light guide plate 101, a part of the light is emitted from the light exit surface (for example, the main surface 101a) to irradiate the liquid crystal panel. Therefore, in order to ensure sufficient luminance of the planar illumination device 100, it is important to first improve the utilization efficiency of the emitted light from the point light source 102. In this regard, the above-described planar illumination device 100 is advantageous in that the positional deviation of the point light source 102 with respect to the light incident surface 101c is small because the FPC 105 is fixed to the light guide plate 101. Have a problem.

すなわち、一般にメタクリル樹脂等の樹脂材料からなる粘着層１０６の屈折率（ｎ2）は、同様な樹脂材料によって成形される導光板１０１の屈折率（ｎ1）に近い値を有するため、点状光源１０２から主面１０１ｂと粘着層１０６との境界に到達した光は、その大部分が透過光として粘着層１０６側に進入し、この境界で反射して導光板１０１の内部へと伝播する光が減少する結果、面状照明装置１００の輝度が低下するという問題があった。特に、図５（ｂ）に示すように、導光板１０１と空気との境界における臨界角（α）以上の入射角を有して主面１０１ｂに到達した光（Ｂ）であっても、ｎ1＞ｎ2の場合には、その入射角が導光板１０１と粘着層１０６との境界における臨界角（β）よりも小さいとき、または、ｎ1＜ｎ2の場合には入射角によらず、全反射は生じないため、反射光（Ｃ）の他に透過光（Ｄ）も発生し、点状光源１０２からの出射光の効率的な利用が妨げられる。このような問題に対処する手段として、フッ素化合物を含有する粘着材のような低屈折率の材料を使用して粘着層を形成することが提案されている（たとえば、特許文献１参照）。
特開２００３−３１５７９２号公報 That is, since the refractive index (n 2 ) of the adhesive layer 106 generally made of a resin material such as methacrylic resin has a value close to the refractive index (n 1 ) of the light guide plate 101 formed of a similar resin material, Most of the light that reaches the boundary between the main surface 101b and the adhesive layer 106 from the light source 102 enters the adhesive layer 106 side as transmitted light, and is reflected at this boundary and propagates into the light guide plate 101. As a result, the luminance of the surface illumination device 100 is reduced. In particular, as shown in FIG. 5B, even if the light (B) reaches the principal surface 101b with an incident angle equal to or greater than the critical angle (α) at the boundary between the light guide plate 101 and air, When 1 > n 2 , the incident angle is smaller than the critical angle (β) at the boundary between the light guide plate 101 and the adhesive layer 106, or when n 1 <n 2 , regardless of the incident angle. Since total reflection does not occur, transmitted light (D) is also generated in addition to reflected light (C), and efficient use of light emitted from the point light source 102 is hindered. As a means for coping with such a problem, it has been proposed to form an adhesive layer using a material having a low refractive index such as an adhesive material containing a fluorine compound (for example, see Patent Document 1).
JP 2003-315792 A

しかしながら、特許文献１に記載されたような手段は、粘着層および導光板に対する材料選択の自由度を制限し、製造コストの増大を招くおそれがあると共に、粘着層として一定の屈折率を有する材料を使用することを許容するものであるため、導光板と粘着層との境界における透過光の発生を抑止する手段として最適なものではなく、光源からの出射光の利用効率の点で改善の余地がある。   However, the means as described in Patent Document 1 limits the degree of freedom of material selection for the adhesive layer and the light guide plate, may increase the manufacturing cost, and has a certain refractive index as the adhesive layer. Therefore, it is not an optimal means for suppressing the generation of transmitted light at the boundary between the light guide plate and the adhesive layer, and there is room for improvement in terms of the efficiency of use of light emitted from the light source. There is.

上記課題に鑑みて、本発明は、容易かつ安価な手段を用いて、点状光源からの出射光の利用効率を改善するサイドライト型の面状照明装置を提供することを目的とする。   In view of the above problems, an object of the present invention is to provide a sidelight type planar illumination device that improves the utilization efficiency of light emitted from a point light source using an easy and inexpensive means.

上記の目的を達成するために、本発明に係る面状照明装置は、一以上の端面を入光面とする導光板と、該導光板の入光面に対向するように配置された点状光源と、該点状光源が実装されるフレキシブルプリント基板と、前記導光板を保持する枠状のハウジングフレームとを備える面状照明装置において、前記フレキシブルプリント基板は、粘着層を介して前記導光板と前記ハウジングフレームとにまたがって一面上に固着され、前記粘着層は、前記点状光源の前方を除いた領域に設けられていることを特徴とする。 In order to achieve the above object, a planar lighting device according to the present invention includes a light guide plate having one or more end faces as a light incident surface, and a spot-like shape disposed so as to face the light incident surface of the light guide plate. In a planar lighting device comprising a light source, a flexible printed circuit board on which the point light source is mounted, and a frame-shaped housing frame that holds the light guide plate , the flexible printed circuit board is arranged on the light guide plate via an adhesive layer. The adhesive layer is provided in a region excluding the front of the point light source.

また、別の態様では、本発明に係る面状照明装置は、前記ハウジングフレームが、前記導光板の入光面に対向する側壁から延在する複数の突出部を有し、前記点状光源は、隣り合う前記突出部の間の空間に配置され、前記粘着層は、前記フレキシブルプリント基板を前記突出部に固着する部分を含むことを特徴とする。   In another aspect, in the planar lighting device according to the present invention, the housing frame has a plurality of protrusions extending from a side wall facing the light incident surface of the light guide plate, and the point light source is The adhesive layer is disposed in a space between the adjacent protruding portions, and the adhesive layer includes a portion that fixes the flexible printed circuit board to the protruding portion.

また、別の態様では、本発明に係る面状照明装置は、前記導光板が、該導光板の入光面から延在する複数の突出部を有し、前記点状光源は、前記導光板の隣り合う前記突出部の間の空間に配置され、前記粘着層の前端は、前記点状光源の光出射面とほぼ同面または前記光出射面よりも後方に配置されていることを特徴とする。   In another aspect, in the planar illumination device according to the present invention, the light guide plate has a plurality of protrusions extending from a light incident surface of the light guide plate, and the point light source is the light guide plate. The front end of the adhesive layer is disposed substantially in the same plane as the light emitting surface of the point light source or behind the light emitting surface. To do.

本発明に係る面状照明装置によれば、点状光源が実装されたフレキシブルプリント基板が粘着層によって導光板に固着されているため、点状光源が導光板の入光面に位置ずれなく配置されるだけでなく、この粘着層は、点状光源の前方を除いた領域に設けられているため、点状光源からの出射光を、粘着層に進入させることなく、導光板と空気との境界における通常の反射により高効率に導光板内部に導くことができ、容易かつ安価な手段によって出射光の利用効率を向上させることが可能となる。   According to the planar illumination device of the present invention, since the flexible printed circuit board on which the point light source is mounted is fixed to the light guide plate by the adhesive layer, the point light source is disposed on the light incident surface of the light guide plate without displacement. In addition, since the adhesive layer is provided in a region excluding the front of the point light source, the light emitted from the point light source does not enter the adhesive layer, and the light guide plate and the air It is possible to guide the inside of the light guide plate with high efficiency by normal reflection at the boundary, and it is possible to improve the utilization efficiency of the emitted light by an easy and inexpensive means.

さらに、本発明に係る面状照明装置において、フレキシブルプリント基板を、導光板を保持する枠上のハウジングフレームにも固着することによって、点状光源の前方の粘着層を削除したことによる固着面積の低下が補われ、点状光源の導光板の入光面に対する位置ずれを効果的に抑制することができ、光源からの出射光の利用効率が向上する。特に、ハウジングフレームの導光板の入光面に対向する側面から複数の突出部を延在させ、フレキシブルプリント基板とハウジングフレームとをこれらの突出部を含めて固着することによって、その密着面積が増大するため、フレキシブルプリント基板とハウジングフレームとがより緊密に固着されることになり、上記位置ずれを抑制する効果が増大する。また、この際、各点状光源を隣合う突出部の間の空間に配置することによって、点状光源から側方または後方に出射された漏れ光が存在する場合でも、それらの漏れ光を点状光源を取り囲む壁により反射し、入光面方向に進路を変更して導光板に入射させることが可能となり、光源からの出射光の利用効率をさらに向上させることができる。   Furthermore, in the planar lighting device according to the present invention, the flexible printed circuit board is also fixed to the housing frame on the frame holding the light guide plate, thereby eliminating the adhesive area due to the removal of the adhesive layer in front of the point light source. The decrease is compensated, and the positional deviation of the point light source with respect to the light incident surface of the light guide plate can be effectively suppressed, and the utilization efficiency of the light emitted from the light source is improved. In particular, by extending a plurality of protrusions from the side facing the light incident surface of the light guide plate of the housing frame and fixing the flexible printed circuit board and the housing frame including these protrusions, the contact area increases. For this reason, the flexible printed circuit board and the housing frame are more closely fixed to each other, and the effect of suppressing the displacement is increased. Also, at this time, by arranging each point light source in the space between the adjacent protrusions, even if there is leakage light emitted from the point light source to the side or rear, the leakage light is turned on. The light is reflected by the wall surrounding the light source, can be changed in the direction of the light incident surface and incident on the light guide plate, and the utilization efficiency of the light emitted from the light source can be further improved.

また、本発明に係る面状照明装置において、導光板の入光面から複数の突出部を延在させ、点状光源を隣り合うこれらの突出部の間の空間に配置することによって、粘着層の前端を点状光源の光出射面とほぼ同面またはそれよりも後方に配置することによって、点状光源からの出射光の指向特性によらず、光出射面から水平方向に広角に出射した光についても、粘着層への進入を確実に回避し、高効率に導光板内部に導くことができる。   Further, in the planar illumination device according to the present invention, the adhesive layer is formed by extending a plurality of protrusions from the light incident surface of the light guide plate and disposing the point light source in a space between the adjacent protrusions. By arranging the front end of the light source approximately on the same plane as the light exit surface of the point light source or behind it, the light is emitted from the light exit surface in a wide angle in the horizontal direction regardless of the directivity characteristics of the light emitted from the point light source. As for light, it is possible to reliably avoid entering the adhesive layer and guide the light into the light guide plate with high efficiency.

以下、本発明の実施の形態を図面に基づいて説明する。図１（ａ）は、本発明の参考例における面状照明装置１０の要部を示す平面図、図１（ｂ）はそのＡ−Ａ線断面図である。この面状照明装置１０は、導光板１１と複数（本参考例では３個）の点状光源１２〜１４とを備え、点状光源１２〜１４は、フレキシブルプリント基板（ＦＰＣ）１５上に実装されて、その光出射面が導光板１１の一端面である入光面１１ｃと対向するように導光板１１の側方に配置されている。また、導光板１１の一主面１１ｂとＦＰＣ１５との間には粘着層１６〜１９が介在し、それによってＦＰＣ１５は導光板１１に固着されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig.1 (a) is a top view which shows the principal part of the planar illuminating device 10 in the reference example of this invention, FIG.1 (b) is the sectional view on the AA line. The planar illumination device 10 includes a light guide plate 11 and a plurality of (three in this reference example ) point light sources 12 to 14. The point light sources 12 to 14 are mounted on a flexible printed circuit board (FPC) 15. Thus, the light emitting surface is disposed on the side of the light guide plate 11 so as to face the light incident surface 11 c that is one end surface of the light guide plate 11. In addition, adhesive layers 16 to 19 are interposed between the one principal surface 11 b of the light guide plate 11 and the FPC 15, whereby the FPC 15 is fixed to the light guide plate 11.

ここで、点状光源１２〜１４は白色ＬＥＤであり、導光板１１は、透明樹脂材料を成形してなる板状の導光体である。導光板として好適な透明樹脂材料には、メタクリル樹脂、ポリカーボネート樹脂、ポリスチレン樹脂、ポレオレフィン樹脂、非晶性ポリオレフィン樹脂、ポリエステル樹脂、ポリスチレン樹脂、透明フッ素樹脂、エポキシ樹脂等が含まれる。なお、本発明における粘着層は、任意の適切な粘着剤または接着剤により形成されるものであるが、好ましくは、たとえばＰＥＴフィルム等の基材の両面にアクリル系やシリコーン系等の粘着剤が塗布されてなるいわゆる両面粘着テープである。この場合、本明細書では、中央の基材部分も含めて粘着層と呼ぶものとする。   Here, the point light sources 12 to 14 are white LEDs, and the light guide plate 11 is a plate-like light guide formed by molding a transparent resin material. Transparent resin materials suitable for the light guide plate include methacrylic resin, polycarbonate resin, polystyrene resin, polyolefin resin, amorphous polyolefin resin, polyester resin, polystyrene resin, transparent fluororesin, epoxy resin and the like. The pressure-sensitive adhesive layer in the present invention is formed of any appropriate pressure-sensitive adhesive or adhesive. Preferably, for example, an acrylic or silicone pressure-sensitive adhesive is provided on both surfaces of a substrate such as a PET film. It is a so-called double-sided adhesive tape that is applied. In this case, in this specification, it shall call an adhesion layer also including the base material part of a center.

図１（ａ）に示すように、本参考例において、粘着層１６〜１９は、点状光源１２〜１４の前方すなわち光出射方向を除いた領域にのみ間欠的に設けられている。したがって、各点状光源の前方において、導光板１１のＦＰＣ１５との固着面である主面１１ｂとＦＰＣ１５との間には空気層が存在するだけであるため、点状光源１２〜１４の前方に出射されて入光面１１ｃに入射し、主面１１ｂに到達した光は、大きな透過率でもって粘着層１６〜１９へ進入することなく、導光板１１と空気との境界における通常の反射によって導光板１１の内部へ導かれる。特に、図１（ｂ）に示すように、導光板１１と空気との境界における臨界角（α）以上の入射角を有して主面１１ｂに到達した光（Ｂ）は、全反射光（Ｃ）としてその全てが導光板１１の内部へ導かれることになる。 As shown to Fig.1 (a), in this reference example , the adhesion layers 16-19 are intermittently provided only in the area | region except the front of the point light sources 12-14, ie, a light-projection direction. Therefore, in front of each point light source, there is only an air layer between the FPC 15 and the main surface 11b, which is a fixed surface with the FPC 15 of the light guide plate 11, and therefore in front of the point light sources 12-14. Light that is emitted and incident on the light incident surface 11c and reaches the main surface 11b is guided by normal reflection at the boundary between the light guide plate 11 and air without entering the adhesive layers 16 to 19 with a large transmittance. Guided into the interior of the light plate 11. In particular, as shown in FIG. 1B, light (B) having an incident angle equal to or greater than the critical angle (α) at the boundary between the light guide plate 11 and air reaches the main surface 11b is totally reflected light ( All of them are guided to the inside of the light guide plate 11 as C).

次に、図２を参照して、本発明の第１の実施形態について説明する。なお、以下の各実施形態の説明において、上述した参考例と同一の部分については同一の符号を付し、その説明を省略する。図２（ａ）は、図１（ａ）に示す面状照明装置１０の構成に加えて、さらにハウジングフレーム２１を備えた面状照明装置２０の要部を示す平面図であり、図２（ｂ）は、図２（ａ）に示す面状照明装置２０を、説明のためハウジングフレーム２１を省略して示した平面図である。ここで、ハウジングフレーム２１は、その中央に導光板１１を収容する領域を有する枠状部材であり、面状照明装置２０を一体のユニットとして保持するものである。ハウジングフレーム２１は、通常、白色顔料を混入した樹脂材料により成形されて高い光反射性を有し、その好適な材料には、白色顔料として酸化チタンを混入したポリカーボネート樹脂が含まれる。なお、導光板１１のハウジングフレーム２１への固定は、任意の接合または係止手段によって実施することができる。 Next, a first embodiment of the present invention will be described with reference to FIG. In the following description of each embodiment, the same parts as those in the reference example described above are denoted by the same reference numerals, and the description thereof is omitted. FIG. 2A is a plan view showing a main part of the planar illumination device 20 having a housing frame 21 in addition to the configuration of the planar illumination device 10 shown in FIG. FIG. 2B is a plan view showing the planar illumination device 20 shown in FIG. 2A with the housing frame 21 omitted for explanation. Here, the housing frame 21 is a frame-like member having a region for accommodating the light guide plate 11 in the center thereof, and holds the planar illumination device 20 as an integral unit. The housing frame 21 is usually molded from a resin material mixed with a white pigment and has high light reflectivity, and suitable materials include polycarbonate resin mixed with titanium oxide as a white pigment. The light guide plate 11 can be fixed to the housing frame 21 by any joining or locking means.

図２（ａ）に示すように、本実施形態において、入光面１１ｃに対向するハウジングフレーム２１の側壁２１ａは、対向する入光面１１ｃに向けて延在する突出部２２〜２５を有し、各点状光源１２〜１４は、隣り合う突出部との間の空間からなる区画２６〜２８にそれぞれ配置されている。また、粘着層３０は、図２（ｂ）に示すように、各点状光源１２〜１４の側方に設けられた領域３１〜３４、および点状光源１２〜１４の後方に設けられた領域３５を有しており、側方領域３１〜３４の先端部３１ａ〜３４ａは導光板１１に、各側方領域３１〜３４の残りの部分は突出部２２〜２５に、後方領域３５は側壁２１ａにそれぞれ対応する。ＦＰＣ１５は、この粘着層３０によって、導光板１１の入光面１１ｃとハウジングフレーム２１の側壁２１ａとを連結して一体化するように、導光板１１およびハウジングフレーム２１の両方に固着されている。   As shown in FIG. 2A, in the present embodiment, the side wall 21a of the housing frame 21 facing the light incident surface 11c has projecting portions 22 to 25 extending toward the opposite light incident surface 11c. Each of the point light sources 12 to 14 is disposed in each of the sections 26 to 28 each including a space between adjacent protrusions. Moreover, as shown in FIG.2 (b), the adhesion layer 30 is the area | regions 31-34 provided in the side of each point light source 12-14, and the area | region provided in the back of the point light source 12-14. 35, the tip portions 31a to 34a of the side regions 31 to 34 are on the light guide plate 11, the remaining portions of the side regions 31 to 34 are on the protrusions 22 to 25, and the rear region 35 is the side wall 21a. Correspond to each. The FPC 15 is fixed to both the light guide plate 11 and the housing frame 21 by the adhesive layer 30 so that the light incident surface 11c of the light guide plate 11 and the side wall 21a of the housing frame 21 are connected and integrated.

ここで、ハウジングフレーム２１は、通常、導光板１１よりも肉厚に形成されて導光板１１よりも高い寸法精度および寸法安定性を有しているため、ＦＰＣ１５を導光板１１のみではなくハウジングフレーム２１にも固着させることは、ＦＰＣ上に実装された点状光源１２〜１４と導光板１１の入光面１１ｃとの位置ずれを抑制する上で有利であり、この際、本実施形態における面状照明装置２０では、ハウジングフレーム２１の側壁２１ａが突出部２２〜２５を有し、粘着層３０が突出部２２〜２５に対応する側方領域３１〜３４を有することによって、ＦＰＣ１５とハウジングフレーム２１との密着面積が増大するため、両者がより緊密に固着されている。ただし、本発明は、粘着層３０のＦＰＣ１５とハウジングフレーム２１とを固着する領域の具体的態様には限定されず、ＦＰＣ１５およびハウジングフレーム２１の形状や粘着領域として使用可能な面積等の条件によって、側方領域３１〜３４のみを有して突出部２２〜２５もしくは突出部２２〜２５と側壁２１ａに固着する場合、または、導光板１１に固着する領域（側方領域３１〜３４の先端部３１ａ〜３４ａに相当する領域）とは別に設けられた後方領域３５によって側壁２１ａに固着する場合を含むものである。   Here, since the housing frame 21 is normally formed thicker than the light guide plate 11 and has higher dimensional accuracy and dimensional stability than the light guide plate 11, the FPC 15 is not only the light guide plate 11 but also the housing frame. 21 is also advantageous in suppressing the positional deviation between the point light sources 12 to 14 mounted on the FPC and the light incident surface 11c of the light guide plate 11, and in this case, the surface in the present embodiment. In the state lighting device 20, the side wall 21 a of the housing frame 21 has protrusions 22 to 25, and the adhesive layer 30 has side regions 31 to 34 corresponding to the protrusions 22 to 25, whereby the FPC 15 and the housing frame 21. Since the contact area with each other increases, both are more closely fixed. However, the present invention is not limited to the specific mode of the region where the FPC 15 and the housing frame 21 of the adhesive layer 30 are fixed, and depending on conditions such as the shape of the FPC 15 and the housing frame 21 and the area that can be used as the adhesive region. When only the side regions 31 to 34 are provided and fixed to the protrusions 22 to 25 or the protrusions 22 to 25 and the side wall 21a, or the region fixed to the light guide plate 11 (the tip 31a of the side regions 31 to 34). To the side wall 21a by a rear region 35 provided separately from the region corresponding to .about.34a).

さらに、本実施形態における面状照明装置２０では、各点状光源１２〜１４は、ハウジングフレーム２１を形成する光反射性の壁に三方を囲まれた各区画２６〜２８にそれぞれ収容されているため、点状光源１２〜１４のパッケージまたは封止材を通じて側方または後方に出射された漏れ光が存在する場合でも、各区画を形成する突出部２２〜２５および側壁２１ａにより漏れ光を反射してその進路を変更し、入光面１１ｃに入射させることができる。ここで、本実施形態では、各区画２６〜２８のハウジングフレーム２１側のコーナー部２６ａ〜２８ａは、図２（ａ）において円弧状の曲線をなす曲面を有するものとした。この形状は、漏れ光の進路を入光面１１ｃ方向へ効果的に変更する上で有利であるが、このコーナー部２０の形状およびサイズは、使用するＬＥＤの発光特性等の条件を勘案の上、適宜設定されるものであり、たとえば、平面による面取り部として形成しても、あるいは、特に曲面化または平面化の処理が施されていないコーナー部としてもよい。さらに、各区画２６〜２８は、点状光源１２〜１４からの漏れ光の入光面１１ｃ方向への反射効率をさらに向上させるため、ハウジングフレーム２１の側壁２１ａ側から導光板１１の入光面１１ｃ側に向けて広がる形状に形成してもよい。   Furthermore, in the planar illumination device 20 according to the present embodiment, the respective point light sources 12 to 14 are respectively accommodated in the sections 26 to 28 surrounded on three sides by the light-reflective walls forming the housing frame 21. Therefore, even when there is leakage light emitted sideways or rearward through the package or sealing material of the point light sources 12 to 14, the leakage light is reflected by the protruding portions 22 to 25 and the side walls 21 a forming each section. Thus, the path can be changed and incident on the light incident surface 11c. Here, in this embodiment, the corner portions 26a to 28a on the housing frame 21 side of the sections 26 to 28 have curved surfaces that form arcuate curves in FIG. This shape is advantageous in effectively changing the path of leakage light in the direction of the light incident surface 11c. However, the shape and size of the corner portion 20 are determined in consideration of conditions such as the light emission characteristics of the LED used. For example, it may be formed as a chamfered portion by a flat surface, or may be a corner portion that is not particularly subjected to curved surface or flattening. Further, each of the sections 26 to 28 has a light incident surface of the light guide plate 11 from the side wall 21a side of the housing frame 21 in order to further improve the reflection efficiency of the leaked light from the point light sources 12 to 14 toward the light incident surface 11c. You may form in the shape which spreads toward 11c side.

上述した第１の実施形態において、一般に、点状光源１２〜１４であるＬＥＤからの出射光は、光出射面から一定の広がりを有する指向特性をもって出射し、その強度は指向角が大きくなる（すなわち前方から逸れる）につれて減少するものの、ＦＰＣ１５と導光板１１とを固着する粘着層は、このような水平方向に広角に出射される光も回避することが望ましい。したがって、図１（ａ）および図２（ｂ）において、粘着層が点状光源１２〜１４の光出射面（入光面１１ｃに対向する面）から突出する部分の長さ（ｌ）、および、点状光源１２〜１４前方における粘着層が形成されない領域の幅（ｗ）、および粘着層の形状は、ＦＰＣ１５と導光板１１の固着強度等も勘案の上、使用する点状光源１２〜１４の指向特性に応じて適宜設定されるものである。 In the first embodiment described above, in general, light emitted from the LEDs that are the point light sources 12 to 14 is emitted with directivity characteristics having a certain spread from the light emission surface, and the intensity thereof has a large directivity angle ( In other words, the adhesive layer that fixes the FPC 15 and the light guide plate 11 desirably avoids light emitted in a wide angle in the horizontal direction. Therefore, in FIGS. 1 (a) and 2 (b), the length (l) of the portion where the adhesive layer protrudes from the light emitting surface of the point light sources 12-14 (the surface facing the light incident surface 11c), and The width (w) of the area where the adhesive layer is not formed in front of the point light sources 12 to 14 and the shape of the adhesive layer are the point light sources 12 to 14 used in consideration of the fixing strength between the FPC 15 and the light guide plate 11 and the like. It is set as appropriate according to the directivity characteristics.

次に、図３を参照して、本発明に係る面状光源装置の第２の実施形態を説明する。図３は、本発明の第２の実施形態である面状照明装置４０の要部を示す平面図である。この面状照明装置４０は、上述した第１の実施形態と同様の構成要素を有してなるものであるが、各点状光源１２〜１４が配置される区画５１〜５３が、導光板４１の入光面４１ｃからハウジングフレーム４２の側壁４２ａに向けて延在する突出部４３〜４６によって形成されている点で相違するものである。また、点状光源１２〜１４の側方に延在する粘着層４７〜５０は、その前側部分が導光板４１の各突出部４３〜４６に、その後側部分がハウジングフレーム４２の側壁４２ａに対応し、ＦＰＣ１５は、この粘着層４７〜５０によって、導光板４１の入光面４１ｃとハウジングフレーム４２の側壁４２ａとを連結して一体化するように、導光板４１およびハウジングフレーム４２の両方に固着されている。 Next, a second embodiment of the planar light source device according to the present invention will be described with reference to FIG. FIG. 3 is a plan view showing a main part of the planar illumination device 40 according to the second embodiment of the present invention. The planar illumination device 40 has the same components as those of the first embodiment described above, but the sections 51 to 53 in which the respective point light sources 12 to 14 are arranged are light guide plates 41. This is different in that it is formed by projecting portions 43 to 46 extending from the light incident surface 41 c toward the side wall 42 a of the housing frame 42. Further, the adhesive layers 47 to 50 extending to the side of the point light sources 12 to 14 have front portions corresponding to the protruding portions 43 to 46 of the light guide plate 41 and rear portions corresponding to the side walls 42 a of the housing frame 42. The FPC 15 is fixed to both the light guide plate 41 and the housing frame 42 so that the light incident surface 41c of the light guide plate 41 and the side wall 42a of the housing frame 42 are connected and integrated by the adhesive layers 47 to 50. Has been.

ここで、本実施形態における面状装置４０では、粘着層４７〜５０の前端４７ａ〜５０ａが点状光源１２〜１４の光出射面（導光板４１の入光面４１ｃに対向する面）とほぼ同面に配置され、図１（ａ）および図２（ｂ）に示すような光出射面から突出する部分（ｌ）を有さないため、図３に示す点状光源１３によって例示するような水平方向に広角に出射される光（Ａ）を、使用する点状光源の指向特性によらずに確実に回避することができる。この際、粘着層４７〜５０の前端４７ａ〜５０ａは、ＦＰＣ１５と導光板４１との十分な密着面積を確保するため、上述したように点状光源１２〜１４の光出射面とほぼ同面に配置することが好ましいが、粘着層４７〜５０の前端４７ａ〜５０ａを点状光源１２〜１４の光出射面よりも後方に配置するものであってもよい。   Here, in the planar device 40 in the present embodiment, the front ends 47a to 50a of the adhesive layers 47 to 50 are substantially the same as the light emitting surfaces of the point light sources 12 to 14 (surfaces facing the light incident surface 41c of the light guide plate 41). Since it is arranged on the same surface and does not have a portion (l) protruding from the light emitting surface as shown in FIGS. 1A and 2B, it is exemplified by the point light source 13 shown in FIG. Light (A) emitted in a wide angle in the horizontal direction can be reliably avoided regardless of the directivity characteristics of the point light source used. At this time, the front ends 47a to 50a of the adhesive layers 47 to 50 are substantially flush with the light emitting surfaces of the point light sources 12 to 14 as described above in order to secure a sufficient contact area between the FPC 15 and the light guide plate 41. Although arrange | positioning is preferable, the front ends 47a-50a of the adhesion layers 47-50 may be arrange | positioned behind the light-projection surface of the point light sources 12-14.

また、本実施形態における面状照明装置は、図４に示す面状照明装置６０のように、導光板６１側の突設部６３〜６６にそれぞれ対向する突設部６７〜７０をハウジングフレーム６２側に形成し、それらの両方の突設部６３〜６６、６７〜７０によって形成される区画７５〜７７に点状光源１２〜１４を配置するものであってもよい。この場合でも、各粘着層４７〜５０は、図３に示す粘着層４７〜５０と同様のものとすることができる。さらに、図３および図４に示す面状照明装置４０、６０において、各区画５１〜５３、７５〜７７の形状、および各区画のハウジングフレーム４２、６２側のコーナー部の形状、粘着層４７〜５０のハウジングフレーム４２、６２側の形状等は、図２に基づいて上述した第１の実施形態の場合と同様に形成することができる。 In addition, the planar illumination device according to the present embodiment includes the projecting portions 67 to 70 facing the projecting portions 63 to 66 on the light guide plate 61 side, like the planar illumination device 60 shown in FIG. The point light sources 12 to 14 may be arranged in the sections 75 to 77 formed on the side and formed by both the projecting portions 63 to 66 and 67 to 70. Even in this case, the adhesive layers 47 to 50 can be the same as the adhesive layers 47 to 50 shown in FIG. Furthermore, in the planar lighting devices 40 and 60 shown in FIG. 3 and FIG. 4, the shape of each section 51 to 53, 75 to 77, the shape of the corner portion on the housing frame 42, 62 side of each section, the adhesive layer 47 to The shape of the 50 housing frames 42, 62 and the like can be formed in the same manner as in the first embodiment described above with reference to FIG.

なお、上述したすべての実施形態を通じて、点状光源は、略四辺形の導光板の一端面に配置されるものとしたが、本発明は、任意の形状の導光板の複数の端面に対して点状光源を配置する場合を含むものである。また、本発明において、点状光源が実装されたフレキシブルプリント基板は、導光板の対向する二つの主面のうちいずれの主面に固着されるものであってもよい。   In addition, although the point light source shall be arrange | positioned at the one end surface of a substantially quadrilateral light-guide plate through all the above-mentioned embodiment, this invention is with respect to the several end surface of the light-guide plate of arbitrary shapes. This includes the case where a point light source is arranged. In the present invention, the flexible printed circuit board on which the point light source is mounted may be fixed to any main surface of the two main surfaces facing the light guide plate.

本発明の参考例における面状照明装置の要部を示す図であり、（ａ）は平面図、（ｂ）は（ａ）のＡ−Ａ線断面図である。It is a figure which shows the principal part of the planar illuminating device in the reference example of this invention, (a) is a top view, (b) is the sectional view on the AA line of (a). 本発明の第１の実施形態における面状照明装置の要部を示す図であり、（ａ）は平面図、（ｂ）は、（ａ）に示す面状照明装置のハウジングフレームを省略して示した平面図である。It is a figure which shows the principal part of the planar illuminating device in the 1st Embodiment of this invention, (a) is a top view, (b) abbreviate | omitted the housing frame of the planar illuminating device shown to (a). It is the shown top view. 本発明の第２の実施形態における面状照明装置の要部を示す平面図である。It is a top view which shows the principal part of the planar illuminating device in the 2nd Embodiment of this invention. 本発明の第２の実施形態における面状照明装置において、点状光源が配置される区画の別の態様を示す平面図である。It is a top view which shows another aspect of the division where a point light source is arrange | positioned in the planar illuminating device in the 2nd Embodiment of this invention. 従来の面状照明装置の典型的な構成を概略的に示す図であり、（ａ）は平面図、（ｂ）はそのＡ−Ａ線断面図である。It is a figure which shows typically the typical structure of the conventional planar illuminating device, (a) is a top view, (b) is the AA sectional view taken on the line.

符号の説明Explanation of symbols

１０，２０，４０，６０ 面状照明装置
１１，４１，６１ 導光板
１２〜１４ 点状光源
１５ フレキシブルプリント基板
１６〜１９，３０，４７〜５０ 粘着層
２２〜２５，６７〜７０ 突出部（ハウジングフレーム側）
４３〜４６，６３〜６６ 突出部（導光板側）

10, 20, 40, 60 Planar illumination device 11, 41, 61 Light guide plate 12-14 Point light source 15 Flexible printed circuit board 16-19, 30, 47-50 Adhesive layer 22-25, 67-70 Projection (housing) Frame side)
43 to 46, 63 to 66 Projection (light guide plate side)

Claims (3)

一以上の端面を入光面とする導光板と、該導光板の入光面に対向するように配置された点状光源と、該点状光源が実装されるフレキシブルプリント基板と、前記導光板を保持する枠状のハウジングフレームとを備える面状照明装置において、
前記フレキシブルプリント基板は、粘着層を介して前記導光板と前記ハウジングフレームとにまたがって一面上に固着され、
前記粘着層は、前記点状光源の前方を除いた領域に設けられていることを特徴とする面状照明装置。 A light guide plate having one or more end faces as a light incident surface, a point light source disposed so as to face the light incident surface of the light guide plate, a flexible printed circuit board on which the point light source is mounted, and the light guide plate In a planar lighting device comprising a frame-shaped housing frame that holds
The flexible printed circuit board is fixed on one surface across the light guide plate and the housing frame via an adhesive layer,
The planar lighting device, wherein the adhesive layer is provided in a region excluding the front of the point light source. 前記ハウジングフレームは、前記導光板の入光面に対向する側壁から延在する複数の突出部を有し、前記点状光源は、隣り合う前記突出部の間の空間に配置され、前記粘着層は、前記フレキシブルプリント基板を前記突出部に固着する部分を含むことを特徴とする請求項１に記載の面状照明装置。 The housing frame has a plurality of protrusions extending from a side wall facing the light incident surface of the light guide plate, and the point light source is disposed in a space between the adjacent protrusions, and the adhesive layer The planar illumination device according to claim 1, further comprising a portion that fixes the flexible printed circuit board to the protruding portion . 前記導光板は、該導光板の入光面から延在する複数の突出部を有し、前記点状光源は、前記導光板の隣り合う前記突出部の間の空間に配置され、前記粘着層の前端は、前記点状光源の光出射面とほぼ同面または前記光出射面よりも後方に配置されていることを特徴とする請求項１または２に記載の面状照明装置。 The light guide plate has a plurality of protrusions extending from a light incident surface of the light guide plate, and the point light source is disposed in a space between the adjacent protrusions of the light guide plate, and the adhesive layer the front end, spread illuminating apparatus according to claim 1 or 2, characterized in that it is arranged to the rear than approximately Domen or the light exit surface and the light emitting surface of the point light source.
JP2004065707A 2004-03-09 2004-03-09 Surface lighting device Expired - Lifetime JP3985231B2 (en)

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