JP4341010B2 - Surface light source device and light guide member - Google Patents

Description

【数２】

で与えられ、さらに点Ｏ2 ，Ｏ3 の座標から、拡散ドット１４の両端の点即ち点Ｏ1 ，Ｏ4 の座標は、各部分１４ａ，１４ｃの長さをぞれぞれｌｅｎｇｔｈ1 ，ｌｅｎｇｔｈ2 として、
【数３】

【数４】

で与えられることになる。
そして、このような構成の拡散ドット１４が、導光部材１１の下面全体に亘って、前述したように導光部材１１の一側１１ａから他側１１ｂに向かって密度が高くなるようにランダムに配置されている。
【００５１】
図５及び図６は、このような拡散ドット１４の配置状態をシミュレーションした結果を示している。
図５（Ａ）における導光部材１１の一側１１ａの片隅の領域Ｒ１と、導光部材１１のｘ方向に関して左側及び中央にて、ｙ方向に関して一側付近，中央付近及び他側付近の各領域Ｒ２乃至Ｒ７について、前述した数式（１）乃至（４）に基づいて各拡散ドット１４の配置のシミュレーションにより、領域Ｒ１については、部５（Ｂ）に示すように、また他の領域Ｒ２乃至Ｒ７については、それぞれ図６（Ａ）乃至（Ｆ）に示すような配置が得られた。
【００５２】
本発明実施形態による面光源装置１０は、以上のように構成されており、光源１３の各点光源１３ａ，１３ｂ，１３ｃからそれぞれ出射した光は、導光部材１１の一側の端面１１ａから導光部材１１内に入射する。
そして、導光部材１１内に入射した光は、導光部材１１の内部に沿って他側１１ｂに向かって進む。その際、光の一部が、導光部材１１の下面に形成された拡散ドット１４に入射し、拡散されると共に、導光部材１１の下方の反射部材１３により反射され、再び導光部材１１内に入射した後、導光部材１１の上面から上方に向かって、出射する。
【００５３】
このようにして、導光部材１１の上面から上方に向かって出射する光は、拡散ドット１４により拡散して反射されることにより、全体として均一に上方に向かって進むことになり、導光部材１１の上方に配置された面状の被照明物（図示せず）を照射する。これにより、被照明物の表面全体がほぼ均一な明るさで照明されることになる。
【００５４】
この場合、各拡散ドット１４は、それぞれ第一の点光源１３ａ，第二の点光源１３ｂ及び第三の点光源１３ｃに対してほぼ垂直な部分１４ａ，１４ｂ，１４ｃを有していることから、各点光源１３ａ，１３ｂ，１３ｃからの光が効率良く入射して拡散されることになり、光の利用効率及び拡散効率が向上するので、導光部材１１の上面全体から均一な光が照射されることになる。
また、各拡散ドット１４がランダムに配置されていることにより、被照明物としての液晶表示装置やさらに光学的作用を付与するためのプリズムシートが導光部材１１の光出射面に対向してが配置される場合に、これらと干渉するようなことはない。
【００５５】
図７は、上述した面光源装置１０における拡散ドット１４の変形例を示している。
まず、図７（Ａ）においては、拡散ドット１４は、中央の部分１４ｂが、幅方向に関して膨らんで、紡錘形状に形成されている。
また、図７（Ｂ）においては、拡散ドット１４は、各部分１４ａ，１４ｂ及び１４ｃの長さ及び幅が互いに異なるように形成されている。
さらに、図７（Ｃ）においては、拡散ドット１４は、中央の部分１４ｂが、光源１３ｂに向かって凹状の円弧状に形成されている。
【００５６】
図７（Ｄ）においては、拡散ドット１４は、図４に示した場合と比較して、各部１４ａ，１４ｂ及び１４ｃの配置順が逆になっている。
図７（Ｅ）においては、拡散ドット１４は、各部分１４ａ，１４ｂ，１４ｃが、互いにその一側が同じ位置に重なって配置されている。
最後に、図７（Ｆ）においては、拡散ドット１４は、各部分１４ａ，１４ｂ，１４ｃが、互いに連続的なスプライン曲線により形成されている。
【００５７】
このようにして、各拡散ドット１４は、互いに光学的な影響を与えない限り、上記線分Ｏ1 Ｏ2 ，Ｏ2 Ｏ3 ，Ｏ3 Ｏ4 を基礎として、微小なずれが許されることにより、種々に変形され得る。
特に、最後に示した図７（Ｆ）のスプライン曲線により連続的に形成された各部分１４ａ，１４ｂ及び１４ｃから成る拡散ドット１４の場合には、拡散ドット１４を構成する各部１４ａ，１４ｂ，１４ｃが不連続な角部を構成しないので、角部による拡散光の輝度ムラの発生が抑制され得ることになる。
【００５８】
上述した実施形態においては、上記導光部材１１は、所定の厚さの扁平な直方体状に形成されているが、これに限らず、一側の端面１１ａから反対側に向かって徐々に薄くなるように、断面が楔形状に形成されていてもよい。
また、上述した実施形態においては、導光部材１１の下面に拡散ドット１４が形成されているが、これに限らず、導光部材１１の上面に、あるいは下面及び上面に拡散ドット１４が形成されていてもよい。
【００５９】
さらに、上述した実施形態においては、光源１３として点光源が使用されているが、これに限らず、導光部材１１の一側の端面１１ａに対して、発光部がその長手方向に分散配置された断続的な光源や、長手方向に関して短い光源であってもよいことは明らかである。
【００６０】
上述した実施形態においては、導光部材１１の下方に反射部材１２が配置されているが、これに限らず、反射部材１２は省略されてもよい。
さらに、上述した実施形態においては、面光源装置１０は、バック照明用の光源装置として構成されているが、フロント照明用の光源装置として構成されていてもよい。
【００６１】
【発明の効果】
以上述べたように、本発明によれば、拡散ドットが一側から他側に向かって密度が高くなるように配置されていると共に、各拡散ドットが、それぞれ個々の光源に対して横向きに拡る部分を有していることから、各光源からの光が、それぞれ各拡散ドットに対して効率良く入射し、拡散されることになるので、光の利用効率が向上すると共に、拡散効率が上昇して、光出射面から出射する光がより均一になり、ムラのない面発光が得られることになる。
このようにして、本発明によれば、簡単な構成により、複数の光源に対して、モアレ等が発生することなく、より均一な面発光を得ることができるようにした面光源装置と、この面光源装置に使用される導光部材が提供され得る。
【図面の簡単な説明】
【図１】本発明による面光源装置の一実施形態の構成を示す（Ａ）平面図及び（Ｂ）側面図である。
【図２】図１の面光源装置における拡散ドットの配置を示す概略平面図である。
【図３】図１の面光源装置における一つの拡散ドットの位置座標を示す平面図である。
【図４】図３に示した拡散ドットの詳細を示す拡大平面図である。
【図５】図３及び図４に示した拡散ドットのシミュレーションにおける（Ａ）領域Ｒ１乃至Ｒ７を示す概略平面図及び（Ｂ）領域Ｒ１における拡散ドットのシミュレーションによる配置を示す拡大平面図である。
【図６】図５（Ａ）の各領域Ｒ２乃至Ｒ７における拡散ドットのシミュレーションによる配置を示す拡大平面図である。
【図７】図４に示した拡散ドットの変形例を示す拡大平面図である。
【図８】従来の面光源装置の一例の構成を示す概略断面図である。
【符号の説明】
１０ 面光源装置
１１ 導光部材
１１ａ 一側の端面
１１ｂ 他側の端面
１２ 反射部材
１３，１３ａ，１３ｂ，１３ｃ 光源
１４ 拡散ドット
１４ａ，１４ｂ，１４ｃ 部分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, for example, a surface light source device used as a front light device or a backlight device for illuminating a liquid crystal display device or the like from the front surface or the back surface, and a light guide member used therefor.
[0002]
[Prior art]
Conventionally, such a surface light source device is configured, for example, as shown in FIG.
In FIG. 8, the surface light source device 1 includes a light guide member 2, a reflection member 3, and a light source 4.
[0003]
The light guide member 2 is made of a translucent material and is formed in a flat rectangular parallelepiped shape having a predetermined thickness.
[0004]
The reflection member 3 is disposed so as to face the entire lower surface of the light guide member 2, and its upper surface is configured as a reflection surface.
As a result, when light emitted downward from the lower surface of the light guide member 2 enters the reflection member 3, the light is reflected by the reflection member 3 and enters the light guide member 2 again from the lower surface of the light guide member 2. Yes.
[0005]
The light source 4 is configured to include a point light source such as an LED or a long light emitting unit such as a cold cathode tube, and is disposed so as to face along the end surface 2a on one side of the light guide member 2. Has been.
[0006]
According to the surface light source device 1 having such a configuration, part of the light emitted from the light source 4 directly enters the light guide member 2 from the end surface 2 a on one side of the light guide member 2.
A part of the light incident on the light guide member 2 is directly emitted upward from the upper surface 2b, and the other part is emitted from the lower surface of the light guide member 2 and reflected by the reflecting member 3. Thereafter, the light enters the light guide member 2 again and exits upward from the upper surface 2b.
Thus, the light emitted from the upper surface of the light guide member 2 irradiates an object to be illuminated (not shown) arranged above the light guide member 2. As a result, the entire surface of the object to be illuminated is back-lit with substantially uniform brightness.
[0007]
Furthermore, in such a surface light source device 1, in order to make light emitted upward from the upper surface 2b of the light guide member 2 substantially uniform over the entire surface, the upper surface or the lower surface of the light guide member 2 (in the case of illustration, On the lower surface, circular diffusion dots 2c are formed by, for example, printing or etching.
Here, the diffusion dots 2c are randomly arranged so that the density gradually increases from the light source side end surface 2a of the light guide member 2 toward the opposite end surface.
When light enters the diffusing dots 2c, the light diffuses and is transmitted or reflected so that light emitted upward from the upper surface of the light guide member 2 has uniform brightness.
However, in the case of the surface light source device 1 provided with such a circular diffusion dot 2c, the directivity with respect to the light source 4 does not occur because each diffusion dot 2c is formed in a circle, but the light from the light source 4 is used. It is not optimal for diffusion, and luminance unevenness occurs in the surface light source.
[0008]
On the other hand, in order to obtain a more uniform surface light emission, the surface light source device by patent documents 1-3 is disclosed.
According to the surface light source device according to Patent Document 1, in order to improve the luminance variation of the directivity distribution of light incident on the light guide member and obtain uniform surface light emission, the directivity distribution of incident light on the light guide member is By providing a pattern for extracting light at an angular position that is too high and guiding light in the angular direction to the outside, the directivity distribution is made more uniform.
[0009]
Moreover, according to the surface light source device by patent document 2, in order to diffuse the light from a light source more favorably, while arrange | positioning a diffusion dot in the fan shape centering on a light source, the angle which looks at each diffusion dot from a light source is set. The distance from the light source increases.
[0010]
Furthermore, according to the surface light source device according to Patent Document 3, in order to diffuse light from the light source better, the direction of the diffusing dots is aligned with a direction substantially perpendicular to the light source.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-260139 [Patent Document 2]
Japanese Patent Laid-Open No. 11-250714 [Patent Document 3]
International Publication No. WO 98/19105 [0012]
[Problems to be solved by the invention]
However, in these surface light source devices according to Patent Documents 1 to 3, the light source is configured as one point light source, and the diffusion dots are also formed and arranged corresponding to one light source. For this reason, when there are two or more light sources, it cannot respond.
Further, in the surface light source devices according to Patent Documents 2 and 3, since the diffusing dots are arranged on the circumference centered on the light source, it is inevitable that periodicity is generated in the arrangement of the diffusing dots. There are problems such as moiré.
[0013]
In view of the above, the present invention provides a surface light source device capable of obtaining more uniform surface light emission without generating moire or the like with respect to a plurality of light sources with a simple configuration, and the surface light source. It aims at providing the light guide member used for an apparatus.
[0014]
According to the first configuration of the present invention, the above object is achieved by a light guide member made of a flat translucent material, and a plurality of light sources distributed and disposed along one end face of the light guide member. And the light guide member includes a plurality of diffusion dots dispersedly arranged on the upper or lower light emitting surface or the opposite surface, and the respective portions of the diffusion dots are continuously connected to each other. Are arranged randomly so that the density increases from one side of the light guide member to the other side, and the light from each light source enters from one end face of the light guide member and is diffused by the diffusion dots A surface light source device that emits light from a light exit surface and uniformly illuminates an object to be illuminated, wherein each of the diffusion dots is substantially perpendicular to a line extending toward each light source. A surface light source device having a portion extending in a direction Ri, is achieved.
[0015]
In the surface light source device according to the present invention, preferably, the light source is arranged at least at two corners on one side of the light guide member.
[0016]
In the surface light source device according to the present invention, preferably, each portion of the diffusing dots has a curved shape with a relatively large radius of curvature.
[0019]
In the surface light source device according to the present invention, preferably, the respective portions of the diffusion dots are arranged so as to partially overlap each other.
[0021]
According to the second configuration of the present invention, the above object includes a plurality of diffusing dots made of a flat translucent material and distributed on the upper or lower light emitting surface or the opposite surface. The diffusion dots are randomly arranged so that the density increases from one side to the other side, and light from a plurality of light sources dispersedly arranged along the end surface of the one side A light guide member for a surface light source device that is diffused by the diffusion dots by being incident from an end surface and is emitted from a light exit surface to uniformly illuminate an object to be illuminated. Are surface light sources characterized in that they have portions formed so as to extend in a direction substantially perpendicular to the lines extending toward the respective light sources and so as not to affect the optical properties of each other. Achieved by the light guide member for the device That.
[0022]
In the light guide member for the surface light source device according to the present invention, each part of the diffusion dots preferably has a curved shape with a relatively large radius of curvature.
[0023]
In the light guide member for the surface light source device according to the present invention, preferably, each portion of the diffusion dots is continuously connected to each other.
[0024]
In the light guide member for the surface light source device according to the present invention, preferably, the portions of the diffusion dots are separated from each other.
[0025]
In the light guide member for the surface light source device according to the present invention, preferably, the portions of the diffusion dots are arranged so as to partially overlap each other.
[0027]
According to said 1st structure, the light radiate | emitted from each light source injects from the end surface of the one side of a light guide member, and advances toward the other side of a light guide member. At that time, a part of the light is directly emitted from the light emitting surface, and the other part is diffused and reflected by the diffusion dots formed on the upper surface or the lower surface of the light guiding member. The light is emitted from the surface to illuminate the object to be illuminated.
[0028]
In this case, the diffusion dots are arranged so that the density increases from one side to the other side, and each diffusion dot has a portion that extends laterally with respect to each light source. Since the light from each light source efficiently enters and diffuses to each diffusion dot, the light utilization efficiency is improved and the diffusion efficiency is increased and emitted from the light exit surface. The light becomes more uniform, and surface emission without unevenness can be obtained.
[0029]
When the light source is disposed at least at two corners on one side of the light guide member, light from each light source enters the light guide member from the entire end surface on one side of the light guide member. As a result, the directivity distribution of incident light becomes even more uniform, the luminance distribution of light emitted from the light exit surface of the light guide member becomes even more uniform, and even more uniform surface light emission can be obtained.
[0030]
When each part of the diffusing dots has a curved shape with a relatively large radius of curvature, each of the parts is formed in an arc shape centering on the corresponding light source. Therefore, the light use efficiency and the diffusion efficiency of the light from the light source are further improved.
[0031]
When the portions of the diffusing dots are continuously connected to each other, the entire diffusing dots are formed smaller.
[0032]
When the portions of the diffusing dots are separated from each other, the individual portions can be easily formed.
[0033]
When the portions of the diffusing dots are arranged so as to partially overlap each other, the entire diffusing dots are each further reduced in size.
[0034]
When each part of the diffusing dots is formed from a continuous spline curve, the connecting part of each part does not form a corner, so that uneven brightness of diffused light due to the corner can be suppressed.
[0035]
Moreover, according to said 2nd structure, when a surface light source device is comprised by disperse | distributing and arrange | positioning a several light source along the end surface of the one side using this light guide member, the above-mentioned 1st As in the case of the configuration, light emitted from each light source enters from one end face of the light guide member and proceeds toward the other side of the light guide member. At that time, a part of the light is directly emitted from the light emitting surface, and the other part is diffused and reflected by the diffusion dots formed on the upper surface or the lower surface of the light guiding member. The light is emitted from the surface to illuminate the object to be illuminated.
[0036]
Here, the diffusion dots are arranged so that the density increases from one side to the other side, and each diffusion dot has a portion that extends laterally with respect to each individual light source. Since the light from each light source efficiently enters and diffuses to each diffusion dot, the light utilization efficiency is improved and the diffusion efficiency is increased and emitted from the light exit surface. The light becomes more uniform, and surface emission without unevenness can be obtained.
[0037]
When each part of the diffusing dots has a curved shape with a relatively large radius of curvature, each of the parts is formed in an arc shape centering on the corresponding light source. Therefore, the light use efficiency and the diffusion efficiency of the light from the light source are further improved.
[0038]
When the portions of the diffusing dots are continuously connected to each other, the entire diffusing dots are formed smaller.
[0039]
When the portions of the diffusing dots are separated from each other, the individual portions can be easily formed.
[0040]
When the portions of the diffusing dots are arranged so as to partially overlap each other, the entire diffusing dots are each further reduced in size.
[0041]
When each part of the diffusing dots is formed from a continuous spline curve, the connecting part of each part does not form a corner, so that uneven brightness of diffused light due to the corner can be suppressed.
[0042]
Thus, according to the present invention, light incident on one end face of the light guide member from a plurality of light sources is formed on the light emitting surface above or below the light guide member or on the opposite surface. By diffusing and reflecting by the diffusion dots, substantially uniform light is emitted from the entire light exit surface of the light guide member.
Then, the diffusion dots have portions formed so as to extend in a direction substantially perpendicular to the lines extending toward the individual light sources and do not affect the optical characteristics of each other, Light from each light source efficiently enters and diffuses to each diffusing dot, so that the light utilization efficiency improves and the diffusion efficiency increases, and the light exits from the light exit surface. Becomes more uniform, and surface emission without unevenness can be obtained.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 7.
The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.
[0044]
FIG. 1 shows a configuration of an embodiment of a surface light source device including a light guide member according to the present invention.
In FIG. 1, a surface light source device 10 is a light source device for back illumination, and includes a light guide member 11, a reflection member 12, and a plurality (three in the illustrated example) of light sources 13. Yes.
[0045]
The light guide member 11 is made of a translucent material, and is formed in a flat rectangular parallelepiped shape with a predetermined thickness, similar to the light guide member 2 in the conventional surface light source device 1 shown in FIG. Yes.
Furthermore, the light guide member 11 has an end surface 11a on one side configured as a light incident surface on which light from the light source is incident, and on the upper surface or the lower surface (lower surface in the case of illustration) as shown in FIG. In addition, diffusion dots 14 that diffuse light are formed by printing, etching, or the like.
Here, the diffusion dots 14 are randomly arranged on the lower surface of the light guide member 11 so that the density gradually increases from the light source side end surface 11a of the light guide member 11 toward the opposite end surface 11b. ing.
[0046]
The reflection member 12 is disposed so as to face the entire lower surface of the light guide member 11, extends from an end surface 11 a on one side of the light guide member 11 to the light source 13, which will be described later, and extends to the lower side thereof. It is formed so as to rise upward on the opposite side of the light source 13 so as to surround the light source 13, and its inner surface is formed as a reflection surface.
Thereby, the light emitted downward from the lower surface of the light guide member 11 is reflected by the reflecting member 12 and returns to the light guide member 11 again, and the light emitted from the light source 13 to the opposite side of the light guide member 11. Is reflected by the rising portion 12 a of the reflecting member 12 and enters from the end surface 11 a on one side of the light guide member 11.
[0047]
Each said light source 13 is comprised from point light sources, such as LED, for example, and is disperse | distributed and arrange | positioned along with the predetermined space | interval so that it may oppose along the end surface 11a of the one side of the said light guide member 11. FIG.
[0048]
The above configuration is substantially the same as that of the conventional surface light source device 1 shown in FIG. 8, but the surface light source device 10 according to the embodiment of the present invention is different in the following points.
That is, in the surface light source device 10, in more detail, each diffusion dot 14 formed on the upper surface or the lower surface of the light guide member 12 has an optimal diffusion surface for each light source 13. As shown in FIGS. 3 and 4, the portions 14a are formed so as to extend in a substantially vertical direction, that is, in a lateral direction with respect to the three light sources 13a, 13b, and 13c, and not to optically influence each other. , 14b, 14c.
[0049]
The first portion 14a of the diffusion dot 14 corresponds to the first light source 13a, the second portion 14b corresponds to the second light source 13b, and the third portion 14c corresponds to the third light source 13c. It corresponds.
Each of the portions 14a, 14b, and 14c is actually formed in a long and narrow rectangle, but in FIG. 4, it is represented by line segments O1 O2, O2 O3, and O3 O4.
[0050]
Here, the center coordinates of the diffusing dots 14, that is, the center coordinates of the central portion 14b are (Xg, Yg), and the positions of the light sources 13a, 13b, 13c are (Lx0, Ly0), (Lx1, Ly1), ( Lx2, Ly2), and the angles of the light sources 13a, 13b, 13c with respect to the central coordinates are α0, α1, α2, respectively. Where the length of the portion 14b is length,
[Expression 1]

[Expression 2]

Further, from the coordinates of the points O2 and O3, the coordinates of the points at both ends of the diffusing dot 14, that is, the coordinates of the points O1 and O4, are the lengths 1 and 2 respectively of the lengths 14a and 14c, respectively.
[Equation 3]

[Expression 4]

Will be given.
The diffusion dots 14 having such a configuration are randomly distributed over the entire lower surface of the light guide member 11 so that the density increases from one side 11a to the other side 11b of the light guide member 11 as described above. Is arranged.
[0051]
5 and 6 show the results of simulating the arrangement state of such diffusion dots 14.
In FIG. 5 (A), a region R1 at one corner of one side 11a of the light guide member 11, the left side and the center with respect to the x direction of the light guide member 11, and the vicinity of one side, the vicinity of the center, and the other side with respect to the y direction. With respect to the regions R2 to R7, the simulation of the arrangement of the diffusion dots 14 based on the above formulas (1) to (4) shows that the region R1 has another region R2 to R2, as shown in the section 5 (B). For R7, the arrangements shown in FIGS. 6A to 6F were obtained.
[0052]
The surface light source device 10 according to the embodiment of the present invention is configured as described above, and light emitted from each of the point light sources 13a, 13b, and 13c of the light source 13 is guided from the end surface 11a on one side of the light guide member 11. The light enters the optical member 11.
Then, the light incident on the light guide member 11 travels along the inside of the light guide member 11 toward the other side 11b. At that time, a part of the light enters the diffusion dots 14 formed on the lower surface of the light guide member 11 and is diffused, and is reflected by the reflection member 13 below the light guide member 11, and again. Then, the light is emitted upward from the upper surface of the light guide member 11.
[0053]
In this way, the light emitted upward from the upper surface of the light guide member 11 is diffused and reflected by the diffusion dots 14, and thus travels upward uniformly as a whole. 11 is irradiated with a planar object to be illuminated (not shown) disposed above 11. As a result, the entire surface of the object to be illuminated is illuminated with substantially uniform brightness.
[0054]
In this case, each diffusion dot 14 has portions 14a, 14b, and 14c that are substantially perpendicular to the first point light source 13a, the second point light source 13b, and the third point light source 13c, respectively. Light from each point light source 13a, 13b, 13c is efficiently incident and diffused, and light utilization efficiency and diffusion efficiency are improved. Therefore, uniform light is irradiated from the entire upper surface of the light guide member 11. Will be.
Further, since each diffusing dot 14 is randomly arranged, the liquid crystal display device as an object to be illuminated and the prism sheet for imparting an optical action are opposed to the light emitting surface of the light guide member 11. When placed, there is no interference with these.
[0055]
FIG. 7 shows a modification of the diffusing dots 14 in the surface light source device 10 described above.
First, in FIG. 7A, the diffusion dot 14 is formed in a spindle shape with the central portion 14b bulging in the width direction.
In FIG. 7B, the diffusing dots 14 are formed such that the lengths and widths of the portions 14a, 14b, and 14c are different from each other.
Further, in FIG. 7C, the diffusion dot 14 has a central portion 14b formed in a concave arc shape toward the light source 13b.
[0056]
In FIG. 7D, the arrangement order of the portions 14a, 14b, and 14c of the diffusing dots 14 is reversed compared to the case shown in FIG.
In FIG. 7 (E), the diffused dots 14 are arranged such that the portions 14a, 14b, and 14c overlap each other at the same position.
Finally, in FIG. 7F, each portion 14a, 14b, 14c of the diffusing dot 14 is formed by a continuous spline curve.
[0057]
In this way, each diffusing dot 14 can be variously deformed by allowing a slight shift based on the line segments O1 O2, O2 O3, O3 O4 as long as they do not optically affect each other. .
In particular, in the case of the diffusing dot 14 composed of the portions 14a, 14b and 14c continuously formed by the spline curve shown in FIG. 7F shown at the end, the portions 14a, 14b and 14c constituting the diffusing dot 14 are provided. Does not constitute a discontinuous corner, so that the occurrence of uneven brightness of diffused light due to the corner can be suppressed.
[0058]
In the embodiment described above, the light guide member 11 is formed in a flat rectangular parallelepiped shape having a predetermined thickness. However, the present invention is not limited to this, and the light guide member 11 gradually becomes thinner from the one end surface 11a toward the opposite side. Thus, the cross section may be formed in a wedge shape.
In the above-described embodiment, the diffusion dots 14 are formed on the lower surface of the light guide member 11. However, the present invention is not limited thereto, and the diffusion dots 14 are formed on the upper surface of the light guide member 11 or on the lower surface and the upper surface. It may be.
[0059]
Furthermore, in the above-described embodiment, a point light source is used as the light source 13, but the present invention is not limited to this, and the light emitting units are dispersedly arranged in the longitudinal direction with respect to the end surface 11 a on one side of the light guide member 11. Obviously, the light source may be an intermittent light source or a light source that is short in the longitudinal direction.
[0060]
In the embodiment described above, the reflecting member 12 is disposed below the light guide member 11, but the present invention is not limited thereto, and the reflecting member 12 may be omitted.
Furthermore, in the embodiment described above, the surface light source device 10 is configured as a light source device for back illumination, but may be configured as a light source device for front illumination.
[0061]
【The invention's effect】
As described above, according to the present invention, the diffusing dots are arranged so as to increase in density from one side to the other side, and each diffusing dot spreads laterally with respect to each light source. Since the light from each light source efficiently enters and diffuses into each diffusing dot, the light utilization efficiency is improved and the diffusion efficiency is increased. Thus, the light emitted from the light emitting surface becomes more uniform, and surface emission without unevenness can be obtained.
Thus, according to the present invention, a surface light source device that can obtain more uniform surface light emission without generating moire or the like with respect to a plurality of light sources with a simple configuration, and this A light guide member used in the surface light source device may be provided.
[Brief description of the drawings]
FIG. 1A is a plan view and FIG. 1B is a side view showing a configuration of an embodiment of a surface light source device according to the present invention.
2 is a schematic plan view showing the arrangement of diffusing dots in the surface light source device of FIG. 1. FIG.
3 is a plan view showing position coordinates of one diffusing dot in the surface light source device of FIG. 1. FIG.
4 is an enlarged plan view showing details of the diffusing dots shown in FIG. 3;
FIGS. 5A and 5B are a schematic plan view showing (A) regions R1 to R7 in the simulation of diffusion dots shown in FIGS. 3 and 4, and an enlarged plan view showing an arrangement of the diffusion dots in the region R1 by simulation.
6 is an enlarged plan view showing an arrangement of diffusion dots by simulation in each of the regions R2 to R7 in FIG.
7 is an enlarged plan view showing a modified example of the diffusing dots shown in FIG. 4. FIG.
FIG. 8 is a schematic cross-sectional view showing a configuration of an example of a conventional surface light source device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Surface light source device 11 Light guide member 11a End surface 11b on one side End surface 12 on the other side Reflective member 13, 13a, 13b, 13c Light source 14 Diffusion dot 14a, 14b, 14c part

Claims (9)

  A light guide member made of a flat translucent material, and a plurality of light sources distributed along one end face of the light guide member. It has a large number of diffusion dots dispersedly arranged on the light emission surface or the opposite surface, and each portion of the diffusion dots is connected continuously to each other and has a density from one side of the light guide member to the other side. The light from each light source enters from the end surface on one side of the light guide member, is diffused by the diffusion dots, and exits from the light exit surface. A surface light source device that uniformly illuminates, wherein each of the diffusion dots has a portion extending in a direction substantially perpendicular to a line extending toward each light source. , Surface light source device.   The surface light source device according to claim 1, wherein the light source is disposed at least at two corners on one side of the light guide member.   3. The surface light source device according to claim 1, wherein each portion of the diffusion dot has a curved shape having a relatively large radius of curvature. 4. The surface light source device according to claim 1, wherein each part of the diffusing dots is disposed so as to partially overlap each other. It is made of a flat translucent material, and has a large number of diffusion dots dispersedly arranged on the upper or lower light emitting surface or the opposite surface, and the diffusion dots have a density from one side to the other side. The light from a plurality of light sources dispersed and arranged along one end face is diffused by the diffusing dots and emitted from the light. A light guide member for a surface light source device that emits from a surface and uniformly illuminates an object to be illuminated,
Each of the diffusing dots has a portion formed so as to extend in a direction substantially perpendicular to a line extending toward the individual light source and so as not to affect the optical characteristics of each other. A light guide member for the surface light source device. 6. The light guide member for a surface light source device according to claim 5, wherein each portion of the diffusion dots has a curved shape having a relatively large radius of curvature. The light guide member for a surface light source device according to claim 5, wherein each portion of the diffusion dots is continuously connected to each other. The light guide member for a surface light source device according to claim 5, wherein each portion of the diffusion dots is separated from each other. The light guide member for a surface light source device according to claim 5 or 6, wherein each part of the diffusing dots is arranged so as to partially overlap each other.

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