Patent Publication Number: US-2011063850-A1

Title: Light box

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a US national stage filing of patent cooperation treaty (PCT) Appln. No. PCT/JP2008/055405 (WO 2008/114882), filed Mar. 24, 2008, which claims priority to Japanese patent application No. 2007-075274, filed on Mar. 22, 2007 and to Japanese patent application No. 2007-220973, filed on Aug. 28, 2007, the entire content of each of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a light box, and in particular, an internal lighting type light box using point like light sources such as LEDs (Light Emitting Diodes), and in more detail, a light box that can be suitably used for electrically illuminated signboards, internal lighting type signs, backlights for liquid crystal displays, and illuminating appliances. 
     BACKGROUND OF THE ART 
     Conventionally, straight tube type light sources such as fluorescent lamps and cold cathode ray tubes have been used for inner-lighting type light boxes. However, the duration life for using the fluorescent lamp is short, and for example, it is said that the duration life of a general straight tube type fluorescent lamp of 40 W is around 12,000 hours, and with respect to light boxes such as signboards at convenience stores and stations mounted at a high level location, it is difficult to change the fluorescent lamps every time the fluorescent lamp becomes out of order, and therefore, all of the fluorescent lamps are changed once in a year, but there are problems such as the need for operations at a high level locations in the night. 
     In directly-underneath type backlights in liquid crystal displays of liquid crystal televisions, they use cold cathode ray tubes that are said to have long duration lives of around 50,000 hours. However, the cold cathode ray tubes have duration lives that end when the brightness becomes half, and consequently, there are problems in that the brightness becomes half after the 50,000 hours. Furthermore, since the cold cathode ray tubes are used by applying a high voltage as high as 1,000V, there are problems in that they tend to be troublesome due to the leakage electricity. 
     Consequently, an inner-lighting type light box which use LEDs as the light source has been proposed, recently (for example, refer to Patent Document 1). The light box that use LEDs as the light source is constructed by arranging a plurality of LEDs densely on a light reflecting surface having a planar shape (LED lamps having a diameter of 3 mm are arranged with 10 mm intervals), and placing a light transparent plastic board in front of the LEDs and the light reflecting surface. By using LEDs as the light source as in the above, it is able to reduce the lowering of the brightness after the 50,000 hours compared with the case that use cold cathode ray tubes, and to reduce the consuming power and the heat by lowering the voltage used. 
     Patent Document 1: Japanese patent un-examined publication 10-83148 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, since the directionality of the radiated light of LEDs are strong, if LEDs are arranged on a planar light reflecting surface, light areas where the LED light directly reaches on the light box surface and dark areas where the light does not reach are originated, and therefore, there was a problem in that an irregularity in the illuminating intensity is observed at the surface of the light box. 
     With only dispersing the emitted light by providing a concave lens or a prism in front of LEDs, or using a light reflecting plate having a light dispersing reflectivity of a visible light 90% or more together with the LEDs, as for light boxes having a thin thickness or light boxes having reduced numbers of LEDs, there was a problem in that it could not prevent irregularities in the illuminating intensity from originating at the surface of the light box. 
     The present invention is achieved in view of the above problems, and its objective is to provide a light box having a thin thickness using light sources with a strong directionality of light, such as LEDs, and a light box that can suppress the irregularities in the illuminating intensity at the surface from originating even when the number of the LEDs is reduced to ¼ to 1/9 of the prior art. 
     Means to Solve the Problems 
     In order to attain the above described object of the invention, the light box of the invention is comprised of: a point like light source; a light reflecting plate arranged around said point like light source; a light diffusion surface plate having light transmissive property and arranged to face said light reflecting plate; a case having an opening formed in a direction of light and for housing at least said point like light source and said light reflecting plate inside; and wherein a receiving concave portion is formed with said light reflecting plate, said point like light source is allocated inside said receiving concave portion, an injection angle of the light from said point like light source is 0°, and a brightness is less than or equal to 15000 cd/m 2  when spaced apart a distance of 350 mm, and a part or all of the light from said point like light source is provided for an illumination after reflecting at an inner surface of a circumferential wall of said receiving concave portion. 
     The point like light source is a light source module, which is arranged in an array on a circuit board, or modularized with a single or a plurality of point like light sources. 
     The point like light source preferably comprises an LED with a point like light emitting portion sealed by a sealing member, and the sealing member is preferably equipped with a light diffusion means. 
     Although the shape of the sealing member is not limited to, but the sealing member preferably comprises a bombshell type sealing member equipped with a light diffusion, or a prism type or a concave lens type sealing member. Furthermore, separate prism or concave lens is preferably arranged in front of the LED. 
     The point like light source is preferably equipped with a light flux control member to scatter the light from the point like light source and emit same. 
     The point like light source preferably comprises a light source module including a LED mounted on a board sealed by a sealing member, and a light flux control member to scatter a light emitted from the LED and to emit same, arranged on a surface of the sealing member through which a light axis emitted from the LED is positioned. 
     The point like light source module is preferably formed such that the light generated from the light emitting portion is emitted through a light flux control member, or the light generated from the light emitting portion is emitted through the sealing member and the light flux control member in this order, the light flux control member includes a light incident face into which the light from the light emitting portion enters the light flux control member, and a light control emitting face to control the light emission from the light emitting portion, concerning the light ranging between a direction to which at least maximum strength light is emitted from the LED and a direction to which one half of strength light of the maximum strength light is emitted, the light control emitting face is formed to satisfy a relation between θ 1  and θ 5  to be (θ 5 /θ 1 )&gt;1 excluding the light in a vicinity of a reference plane, where the angle formed between the light entering the light flux control member and reaching the light control emitting face, and the line parallel to a reference light axis of the light source module and passing the reaching point is represented by the angle θ 1 , and an angle of the emission of the light from the light control emitting face is referred to as the angle θ 5 , and the light control emitting face is formed to be the shape in such fashion that a value of θ 5 /θ 1  is gradually reduced as the θ 1  increases. 
     The receiving concave portion is preferably formed in a reversed multi sided pyramid shape or a reversed multi sided pyramid shape, with a top thereof cut, surrounding said point like light source. Furthermore, if it is formed as a reversed multi sided pyramid shape having its narrow portion cut-off, it is more preferable to have a bottom portion. 
     It is preferable that the apex portion of said receiving concave portion is respectively connected to an apex portion of an adjacent receiving concave portion, and an apex portion of said receiving concave portion is located on a location at or below a bisection point of a distance from an emitting portion of said point like light source to said light diffusion surface plate, and at or above an emitting portion of said point like light source. More specifically, preferably, it is less than or equal to the distance of a bisection point and greater than or equal to a trisection point. 
     The scatter reflectivity of a visible light in the light reflecting plate is preferably at least 80%. The light reflecting plate preferably comprises a thermoplastic resin film or sheet which has fine foams or pores having an average diameter within the range from at least wavelength of the light to 50 μm inside thereof. Furthermore, the thermoplastic film or sheet preferably comprises a thermoplastic polyester foam having a thickness of within the range of from 150 to 2000 μm, and a specific gravity of within the range of from 0.1 to 0.7. 
     The total light ray transmissivity of the light diffusion surface plate is preferably, 20-70%, and more preferably, 30-60%. 
     The depth distance of said case is preferably formed in a range of 40-60 mm, and said plurality of point like light sources are arranged preferably in a matrix having intervals of longitudinal and lateral directions respectively in a range of 80-120 mm. The depth distance in this case means the distance from an inner surface of the bottom of the case to the light diffusion surface plate (hereinafter the same). 
     More preferably, the depth distance of said case is formed in a range of 20-40 mm, and said plurality of point like light sources are arranged in a matrix having intervals of longitudinal and lateral directions respectively in a range of 40-80 mm. 
     EFFECT OF THE INVENTION 
     According to the light box of the present invention, excellent advantageous effects are achieved such as suppressing the origination of the irregularities in the illuminating intensity at the surface, even for a light box having a thin thickness using light sources having strong directionalities of the light, such as LEDs, and even if the number of the LEDs is reduced to ¼- 1/9 of the prior art. 
     Furthermore, since the receiving concave portion of the light reflecting plate is formed in a reversed multiple angle corn shape or a reversed multiple angle corn shape with a top thereof cut, the light reflected at the receiving concave portion reflects effectively at the side surface of the receiving concave portion, and since a large amount of the light even reaches onto the spaces between the light sources where the light intrinsically does not reach much, by producing synergistic effects with the sealing member and the light flux control member provided at forefront of the point like light sources in the present invention, the present invention achieves excellent advantageous effects, such as suppressing the origination of the irregularities in the illuminating intensity at the surface while achieving a thinner light box, even if the number of the point like light source is small. 
     Moreover, since the light reflecting plate of the present invention becomes closer to the light diffusion surface plate as moving away from the light sources, it contributes to reducing the irregularities in the light by making the light that did not transmit the light diffusion surface plate and that returned to the inside to return to the light diffusion surface plate side again effectively. 
    
    
     
       BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS 
         FIG. 1  is a partially-cut top view of the main region of the first embodiment of the light box according to the present invention. 
         FIG. 2  is a cross-sectional view of the main region in  FIG. 1 . 
         FIG. 3  is a cross-sectional view showing a modification example of the light flux control member of the light source module in  FIG. 1 . 
         FIG. 4  is a magnified illustrative cross-sectional view showing another example of the main region of the light source module in  FIG. 1 . 
         FIG. 5  is a similar figure with  FIG. 4 , illustrating the light flux control member in  FIG. 4 . 
         FIG. 6  is a partially-cut top view of the main region of the second embodiment of the light box according to the present invention. 
         FIG. 7  is a cross-sectional view of the main region in  FIG. 6 . 
         FIG. 8  is a partial cross-sectional view showing another example of the main region of the receiving concave portion in  FIG. 6 . 
         FIG. 9  is an illustrative diagram showing an example of the method for manufacturing the light reflecting plate in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, the present invention will be described together with the embodiments shown in the drawings. 
       FIG. 1  and  FIG. 2  show a first embodiment of the light box according to the present invention, and  FIG. 1  is a partially-cut top view of the main region and  FIG. 2  is a cross-sectional view of  FIG. 1 . 
     In the exemplary light box according to the first embodiment, a single point like light source is made into a module, and the modules are arranged in an array as the plurality of point like light sources. 
     As shown in  FIG. 1  and  FIG. 2 , the light box (an illuminating apparatus having a surface light source) according to the first embodiment has a case  2  in which openings are formed in the side where the lights (an upwards direction in  FIG. 2 ). The case  2  is comprised of a planar type bottom board  2   a  forming a rectangular shape, and four side boards  2   b  that stands up on four sides of the bottom board  2   a , and is formed in a box outlook having a rectangular top view in which openings are provided in the upper region in  FIG. 2  which is at the output side of the whole outlook. As for the case  2 , it may be of any kind that is able to receive at least a plurality of point like light sources and a light reflecting plate  21  in its inside. The light diffusion surface plate  26  has preferably, the total light ray transmission rate of 20-70%, and more preferably, 30-60%. 
     Examples of the material for said case  2  include a steel board, an aluminum board, and a thermoplastic resin. Among those, a steel board, an aluminum board, an acrylic board, and a molded product are preferred since they exhibit good mechanical strength, antiweatherability, heat resistivity, impact resistivity, etc. 
     As for the thickness distance (the height of the entire light box), 40-60 mm is preferable since it is a level required for the facade signboards at convenience stores. Furthermore, 20-40 mm is preferable considering that it is a level required for backlights in liquid crystal televisions. 
     Moreover, considering the heat dissipation and the dampening of the expansion and shrinking of each of the members, it is preferable to enlarge the size of the hole of the insertion holes  23  of the light reflecting plate  21 , that will be described later, 1 mm or more larger for each sides compared with the sides of the inserting-through region of the light source. 
     At the bottom of the case  2 , light source modules  3  are arranged in a matrix shape as a plurality of point like light sources. 
     The light source module  3  according to the first embodiment is made by modularizing a single point like light source, and is arranged to include an LED  4  having a single point-type emitting portion  4   a , and more specifically, a board  5  (circuit board) on which an LED chip is implemented is sealed with a sealing member  6  so that it forms a planar shape as a whole, and a light flux control member  7  to scatter the light from the LED  4  on a surface located on a light axis LC of the light from the LED  4  (the forward direction of the light at the center of the three-dimensional light flux output from the LED  4 ; shown with an arrow in  FIG. 2 ). As for the light flux control member  7 , those that can scatter the light from the LED  3  uniformly and smoothly for output are preferable. 
     As for the shape of the light flux control member  7 , it only requires to be a shape that can scatter the light from the LED  4  for output, and For example, the light flux control member has a shape like a disk and the upper face of the upper portion of which looks like a partially defect sphere. In addition, the light flux control member may have a shape like a disk, the upper face of the upper portion of which looks like a partially defect sphere, and the end edge of the upper face of the upper portion of which has a smoothly curbed portion. Further, the light flux control member may have a shape like a disk, and the lower face of the upper portion of which looks like a partially defect sphere. The light flux control member may also have a shape looks like a disk, and the upper face of the upper portion of which has a cone-shaped concave portion with the bottom positioned in the center thereof. The light flux control member may also have a shape looks like a disk, the upper face of the upper portion of which has a parabolic concave curve from the peripheral border of the portion toward the bottom positioned in the center thereof. The light flux control member also may have a shape like a disk, the upper face of the upper portion of which has a sharp concave portion with the bottom positioned in the center thereof, and the side portion of the upper face of which has a respective square corners (refer to  FIG. 3 ). 
     The surface of the light flux control member  7  may be etched to be like a frost glass to allow an additional function of the light scattering. 
     As the material of the light flux control member  7 , such transparent resin material as PMMA (polymethylmethacrylate), PC (polycarbonate), EP (epoxy), or transparent glass are preferable. 
     The module is a circuit component assembling wired circuit elements, and manufactured according to the standardized size, thus having the standardized plug in terminal or the terminal enabling to be soldered. 
     As for the light source module  3 , specific examples include a module that uses Shining Eye (L) (a product name made by Koha Co. Ltd.) or LEC (Light Enhancer Cap; Enplas Display Device Corporation made) as the light flux control member  7 . 
     As for the light source module  3 , it is preferably formed so that the incident angle of the light from the LED  4 , that is, a single point like light source, is 0° and the brightness is 15000 cd/m 2  or less at a location where a distance of 350 mm is spaced apart in a situation where a light diffusion surface plate  26  to be described later is detached (hereinafter simply referred to as the “brightness of LED  4 ”), and a part or all of the light from a single LED  4 , which is a point like light source, is dispersed to be used for the illumination after reflecting at the inner surface of the receiving concave portion  22  of the light reflecting plate  21 , which will be described later. 
     The upper limit of the brightness of the LED  4  is 15000 cd/m 2 , and more preferably, 2000 cd/m 2 , and it is therefore possible to reduce the brightness of the light that directly reaches to the light diffusion surface plate  26 . Furthermore, the lower limit of the brightness of the LED  4  is 100 cd/m 2 , and more preferably, 300 cd/m 2 . Even if the above brightness is low, it only requires that the lights in the diagonal and lateral directions and is dispersion-reflected at the light reflecting plate  21 , that the scattered light reaches to the light diffusion surface plate  26 , and that the irregularities in the light at the surface of the light box  1  is reduced. 
     The light that reached to the light diffusion surface plate  26  transmits to the outside based on the total light ray transmissivity, and almost all of the rest of the light returns back to the inside of the case  2 , but upon the returned backlight is dispersion-reflected at the light reflecting plate  21  to be described below, it contributes to further reducing the irregularities in the light at the surface of the light box  1 , because the farther the light reflecting plate  21  is from the light source, the closer it is to the light diffusion surface plate  26 . 
     The brightness in this context indicates a value measured using a brightness meter by placing a distance L of 350 mm between a location located on the light axis LC of the surface of the sealing member  6  which is the top portion  4   b  of the LED  4  and the measuring segment BMa of the brightness meter BM. It is noted that the light is directly measured by detaching the light diffusion surface plate  26 . 
     As the color of the emitted light from the point like light source, various kind of color such as red, green, blue, yellow, white or the like can be used by itself or in combination with the other. 
     The brightness of the point like light source can be appropriately selected, considering the scope of the invention according to the conditions. 
     Furthermore, as for the light source module  3 , it may be modularized with a plurality of point like light sources. 
     The light source module  3  is arranged in a matrix shape in which its emitting portion  4   a  is oriented to the opening side and the longitudinal and lateral intervals are equally spaced. However, the longitudinal and lateral intervals of the light source module may be different due to the manufacturing reasons of the light box. 
     As for the longitudinal and lateral intervals upon arranging the light source modules  3  in a matrix shape, it is preferable to form each of them equal if the depth distance of the case  2  is formed in a range of 40-60 mm, but even if they cannot be made equal due to the size of the light box, it is preferable to set the intervals such that the maximum interval is in a range of 80-120 mm. As for the longitudinal and lateral intervals, it is preferable to form each of them equal if the depth distance of the case  2  is formed in a range of 20-40 mm, but even if they cannot be made equal due to the size of the light box, it is preferable to set the intervals such that the maximum pitch is in a range of 40-80 mm. As previously described, the depth distance of the case  2  in this context indicates a distance from the inner surface of the bottom of the case  2  to the light diffusion surface plate  26 , that is, the distance between the bottom board  2   a  of the case  2  and the light diffusion surface plate  26 . 
     As for the light source module  3 , the light source module  3 A shown in  FIG. 4  and  FIG. 5  may be used. The light source module  3 A is formed to output the light from the emitting portion  4   a , which is a point like light source of the LED  4  implemented on the board  5  (circuit board), via the light flux control member  9 , or the light from the emitting portion  4   a , which is a point like light source of the LED  4  implemented on the board  5 , via the sealing member  6  and the light flux control member  9  in this order. 
     The sealing member  6  is formed to hemispherically cover the light emitting portion  4   a  of the LED  4  mounted on the board  5 . 
     As the material of the light flux control member  9 , such transparent resin material as PMMA (polymethylmethacrylate), PC (polycarbonate), EP (epoxy), or transparent glass are preferable. 
     The light flux control member  9  has a circular shape in horizontal plane. As depicted in  FIG. 4 , which is a cross sectional view, the light flux control member  9  has a concave portion  11  inside thereof (the lower side in  FIG. 4 ) so as to closely cover the light emitting face  10  of the LED  4 . The concave portion  11  is formed at the inner side of the light flux control member  9  (the lower side in  FIG. 4 ) to be like the hemispherical in the center thereof. The hemispherical shape of the concave portion  11  of the light flux control member  9  corresponds to the shape of the light emitting face  10  of the LED so that the concave portion  11  is closely fit to the light emitting face  10 . The lower side of the light flux control member  9 , which has a flat face portion  12 , is adhesively fixed to the board  5  mounting the LED  4 . Thus, the concave portion  11  of the light flux control member  9  is adhesively fixed to the light emitting face  10  of the LED  4 . 
     The light flux control member  9  has a light control emitting face  13  at the outer surface thereof. The light control emitting face  13  has the first emitting face  13   a , which is located at the prescribed region with the light axis LC as its center, and the second emitting face  13   b  which is continuously formed at the peripheral of the first emitting face  13   a . The first emitting face  13   a  has a smoothly and downwardly protruding curbed shape (i.e., convex downward). In other words, an upper part of the sphere is cut and the concave shape is formed in the center portion thereof. The second emitting face  13   b  is formed continuously to the first emitting face  13   a , which has a curbed shape of smooth and convex. The second emitting face  13   b  has a hollow disk shape in the horizontal plane which surrounds the first emitting face. The first emitting face  13   a  is smoothly connected to the second emitting face  13   b . The connecting portion of the first emitting face  13   a  and the second emitting face  13   b  forms the point of inflexion Po. 
     The third emitting face  13   c  is formed at the outer peripheral side of the second emitting face  13   b  forming the light control emitting face  13 , which connects the second emitting face  13   b  to the flat face portion  12 . Although the third emitting face  13   c  is shown to have a straight slant face in  FIG. 4 , the shape of the third emitting face is not limited to the above described feature. The shape of the third emitting face may be a curved face as far as it does not prevent the wide and smooth emitting of the light flux control member  9 . Here, the angle formed between the light axis LC and the line connecting the light source to the connecting point Pa of the emitting faces  13   b  and  13   c  is represented by δ 1 . The angle formed between the light axis LC and the line connecting the light source to the point of inflexion Po is represented by δ 2 . 
     Here, the light control emitting face  13  of the light flux control member  9  is described in detail with reference to  FIG. 5 . 
     As depicted in  FIG. 5 , the horizontal face perpendicular to the light axis LC of the LED  4  is considered as the reference plane C. The position where the light H emitted from the LED  4  and propagated in the light flux control member  9  emits from the light control emitting face  13  is considered as the position Px (i.e., the intersection of the light control emitting face  13  and the light H). The line drawn parallel to the reference plane C from the position Px is represented by the line A. The angle formed between the light incident in the light flux control member  9  and reaching the light control emitting face  13 , and the line parallel to the light axis LC and passing the point in which the above described light reaches at the light control emitting face  13  is represented by the angle θ 1 . The angle formed between the tangent line B in the contour of the light control emitting face  13  at the position Px, and the line A is referred to as the angle θ 3 . Where the position Px is the position where the light H from the LED  4  emits from the light control emitting face  13 . The angle of the emission of the light H emitting from the light control emitting face  13 , which propagates in the light flux control member  9  from the LED  4 , is referred to as the angle θ 5  (i.e., the angle formed between the light axis LC and the light H emitting from the light control emitting face  13 ), in  FIG. 7 . 
     The light control emitting face  13  depicted in  FIG. 7  is formed to satisfy the relation between θ1 and θ 5  to be (θ 5 /θ 1 )&gt;1, within the prescribed region including the angle region (excluding the light in the vicinity of the normal line (the light axis LC in  FIG. 7 ) between the direction to which at least maximum strength light is emitted from the LED  4  and the direction to which one half of strength light of the maximum strength light is emitted. Where the direction to which at least maximum strength light is emitted means the direction along the light axis LC, as well as the direction along the normal line of the reference plane C, and the prescribed angle region is within the angle region of θ 1 &lt;δ 1 . The light control emitting face is formed to be the shape so that the value of θ 5 /θ 1  is gradually reduced as the θ 1  increases. 
     When the coefficient of the diffusion degree of the light flux control member  9  is represented by α, θ 5  is expressed within the region of θ 1 &lt;δ 1  by (1+((δ 1 −θ 1 )×α)/δ, (θ 1 &lt;δ 1 ). Furthermore, θ 3  is expressed within the region of θ 1 &lt;δ 1  by tan−1((sin θ 5 −n·sin θ 1 )/(cos θ 5 −n·cos θ 1 )), (n is the refraction index of the light flux control member). The vicinity of the above described normal line (i.e., light axis LC in  FIG. 5 ) means that θ1 is preferably within a range of ±5 degrees, for example. 
     Thus obtained θ 3  is gradually reduced, as θ 1  increases from the vicinity of light axis LC until θ 1 =δ 2 . In the region of θ 1 &gt;δ 2 , θ 3  gradually increases, as θ 1  increases. Then, when θ1 becomes to coincide with δ 1 , it satisfies θ 3 =θ 1 . 
     The function of the light control emitting face  13  in the light flux control member  9  is described. As depicted in  FIG. 5 , the light H from LED  4  is propagated inside of the light flux control member  9 , and then emits from the light control emitting face  13  to the outside (in the air) according to Snell&#39;s law. In this case, the light flux of the LED  4  emitted from the light flux control member  9  is not partially emitted at the direct overhead of the LED  4 , but uniformly and smoothly expanded and emitted into the irradiating region, comparing with the light flux emitted from the light flux control member simply formed in hemisphere shape. 
     More specifically, preferably, the light source module  3 A may be formed such that the light generated from the light emitting portion  4   a  as the point like light  3   a  source is emitted through the light flux control member  9 . Alternatively, the light generated from the light emitting portion  4   a  as the point like light  3   a  source is emitted through the sealing member  6  and the light flux control member  9  in this order. The light flux control member  9  may includes the light incident face (the concave face of the concave portion  11 ) into which the light from the light emitting portion  4   a  of the point like light  3   a  source or the light from the light emitting portion  4   a  sealed by the sealing member  6  enters, and light control emitting face  13  to control the light emission from the light emitting portion  4   a . Concerning light ranging between the direction to which at least maximum strength light is emitted from the LED  4  and the direction to which one half of strength light of the maximum strength light is emitted, the light control emitting face  13  may be formed to satisfy the relation between θ 1  and θ 5  to be (θ 5 /θ 1 )&gt;1 excluding the light in the vicinity of the reference plane. Where the angle formed between the light reaching the light control emitting face  13 , and the line parallel to the light axis LC of the light source module  3 A and passing the reaching point is represented by the angle θ 1 , and the angle of the emission of the light from the light control emitting face  13  is referred to as the angle θ 5 . Furthermore, the light control emitting face may be formed to be the shape in such fashion that the value of θ 5 /θ 1  is gradually reduced as the θ 1  increases. 
     As the light source module  3 A, specifically, the module in which LEC (Light Enhancer Cap: the product of Enplas Display Device Corporation) is used as the light flux control member  9  can be exemplified. 
     As for the light source module  3 ,  3 A, it may be modularized with a plurality of point like light sources. 
     Returning back to  FIG. 1  and  FIG. 2 , a light reflecting plate  21  is housed inside of the case  2 . The light reflecting plate  21  is for reflecting the light from the light source module  3  which is a plurality of point like light sources, and is arranged to face the upper surface of the sealing member  6  of the light source module  3 . 
     The light reflecting plate  21  includes a plurality of receiving concave portions  22  that surrounds each of the plurality of point like light sources and that surrounds the circumferences of each of the light flux control members  7  of each of the light source modules  3  in the first embodiment, and insertion holes  23  that can freely insert through the light flux control members  7  of the light source modules  3  formed at the center of the bottom of receiving concave portions  22 . As for the shape of the insertion hole  23 , it can be of any shape although it is a planar circle shape in the first embodiment. 
     The receiving concave portion  22  according to the first embodiment is formed as a reversed multi sided pyramid shape with the narrow portion cut-off (an upside down multi sided pyramid shape with the narrow portion cut-off; hereinafter referred to as a “truncated reversed multi sided pyramid shape”), and more specifically, is formed as a reversed quadrangle pyramid shape with the narrow portion cut-off (an upside down quadrangle pyramid shape with the narrow portion cut-off; hereinafter referred to as a “truncated reversed quadrangle pyramid shape”), and the top portions  22   a  of each of the receiving concave portion  22  are arranged so that they locate in a single plane. Needless to say, the receiving concave portion  22  may be a reversed multi sided pyramid shape. Each of the top portions  22   a  of the plurality of receiving concave portions  22  is preferably connected to the top portion  22   a  of the adjacent receiving concave portion  22 . The top portions  22   a  of the adjacent receiving concave portions  22  may be arranged to push together. 
     In other words, in the light box  1  according to the first embodiment, the light reflecting plate  21  is arranged so that it fits into the space between each of the light source modules  3 , and the light flux control member  7  of each of the optical source modules  3  projects at the insertion hole  23  provided at the bottom of the receiving concave portion  22  which has a truncated reversed multi sided pyramid shape. As for the size of the insertion holes  23 , it is preferable to form them 1 mm or larger at one side of them, compared with the size of the insertion-through region of the light source module  3 . 
     Therefore, the light source modules  3  are arranged and wired in advance at the inner surface of the bottom board  2   a  of the case  2 , in order for the light flux control member  7  of the light source module  3  to project in the direction of the openings of the case  2  from the insertion hole  23  of the bottom of each of the receiving concave portion  22 . 
     As for the shape of the receiving concave portion  22 , it is not limited to the truncated reversed quadrangle pyramid shape, and it may be other truncated reversed multi sided pyramid shape, such as a truncated reversed triangular pyramid shape, a truncated reversed pentangular pyramid shape, and a truncated reversed hexangular pyramid shape. The shape of the receiving concave portion  22  may be appropriately selected among various kinds such as reversed multi-sided pyramid, cup type, pot type, hemisphere type, semielliptical sphere with the through hole in the bottom as insertion hole  23 , depending on the specification or design concept. 
     The vertex angle of the vertex  22   a  of the receiving concave portion  22  formed in a truncated reversed quadrangle pyramid shape according to the first embodiment is 60-120°, and preferably, 80-100°. The height of the vertex  22   a  is greater than or equal to the height of the emitting portion  4   a  of the light source, and is less than or equal to the bisection point of the distance from the emitting portion  4   a  to the light diffusion surface plate  26 , and preferably, less than or equal to the bisection point and greater than or equal to the trisection point. 
     It is preferable to space apart 1 mm or more at a space between the peripheral wall of the insertion hole  23  of the light reflecting plate  21  and the light flux control member  7  of the light source module  3 , for the purpose of dissipating the heat originated at the LED  4 , etc., and relieving the mismatch of the positions of the case  2  and the light reflecting plate  21  due to the differences in the coefficient of thermal expansion. 
     The light reflecting plate  21  is preferably formed by thermoplastic resin film or sheet which has fine foams or pores having an average diameter within the range from at least wavelength of the light to 50 μm inside thereof. 
     As the material of the thermoplastic resin film or sheet, there are exemplified as follows, for example: general purpose resin such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polychlorinated biphenyl, polyethylene terephthalate, polyvinyl alcohol, engineering plastic such as polycarbonate, polybutylene terephthalate, polyethylene naphthalate, polyamide, polyacetal, polyphenylene ether, ultrahigh molecular polyethylene, polysulfone, polyether sulfone, polyphenylene sulfide, polyallylate, polyamide-imide, polyether imide, polyether ether ketone, polyamide, polytetrafluoroethylene, liquid crystal polymer, fluorine resin, or copolymer or mixture of the above. Polyester, polyphenylene sulfide, polypropylene, or cyclopolyolephine is preferable in the above described, since they are excellent in heat resistance, impact resistance or the like. 
     Antioxidant, ultraviolet absorber, lubricant, pigment, enhancement or the like can be added to the thermoplastic resin. In addition, a coating layer containing the above described addition agent may be applied. 
     More specifically, as an example of the thermoplastic resin film or sheet, polyester based foam sheet (for example, MCPET (registered trademark) manufactured by Furukawa Electric Co. Ltd) can be used. The above described polyester based foam sheet is the sheet having a foam diameter of up to 50 μm therein in which an extruded sheet of the thermoplastic polyester is caused to impregnate carbon dioxide gas under high pressure, and then heated and foamed. In addition, cyclopolyolephine based foam sheet having a foam diameter of up to 50 μm therein can be applied. 
     As a preferable example of the material forming the light reflecting plate  21 , there can be exemplified thermoplastic film or sheet containing filler in which a number of voids are formed on the filler functioning as the core. In this case, a porous stretched film or sheet with a number of voids formed on the filler functioning as the core is preferable, in which the film or sheet is manufactured by the processes that an un-stretched film or sheet containing fillers is formed, and then the un-stretched film or sheet is stretched. 
     Thickness of the light reflecting plate  21  is preferably within the range of from 150 to 2000 μm. With the thickness range of 150 to 2000 μm, the light reflecting plate has rigidity, and few light leaks to the back side of the light reflecting plate  21 . 
     The specific gravity of the light reflecting plate  21  is preferably within the range of from 0.1 to 0.7. With the specific gravity of over 0.7, the light reflecting plate becomes transparent, and a lot of light leak to the back side of the light reflecting plate  21 , thus enlarging the light loss. 
     The diffuse reflectivity of the visible light in the light reflecting plate  21  is preferably at least 80%. With the diffuse reflectivity of at least 80% in the light reflecting plate  21 , the scattered reflection effect of the light source is improved. 
     Meanwhile, the diffuse reflectivity of the visible light is a ratio of the diffuse reflective light flux to the incident light flux. More specifically, the diffuse reflectivity is measured by the spectrophotometer with the wavelength of 555 nm, and is obtained as the relative value to the standard value, when the diffuse reflectivity of the white plate with fine powder of barium sulfate fixed thereon is 100%. As the spectrophotometer, UV-3100PC (the product name of Shimadzu Corporation) can be used, for example. 
     As for the manufacturing method of the light reflecting plate  21 , it may be formed integrally by press processing the film or the sheet, as in food trays. In this case, it is formed integrally so that the top portion  22   a  of each of the receiving concave portions  22  is connected to the top portion  22   a  of the adjacent receiving concave portion  22 . Alternatively, it may be assembled as in parquets. Furthermore, since it is housed in the case  1 , each of the receiving concave portions  22  may be formed individually and may be housed in the case  1  so that each top portion  22   a  pushes together. 
     At the upper side of the light reflecting plate  21 , a transmissive light diffusion surface plate  26  is allocated. The light diffusion surface plate  26  is fixed to the opening end of the case  2  with a double-sided adhesive tape, an adhesive agent, screws, etc., so that it shuts the opening of the case  2  and faces the light reflecting plate  21 . Needless to say, it may be mounted onto the opening end of the case  2  freely detachably. 
     As for the light diffusion surface plate  26 , those having a total light ray transmissivity in a range of 20-70% and a reflectivity in a range of 30-80% are used suitably, and examples include an acrylic resin board, a polycarbonate board, a glass cloth, and a vinyl chloride resin sheet. If the total light ray transmissivity is within a range of 20-70%, the amount of the light source required for obtaining the brightness of the light diffusion surface plate  26  is not too large and it does not transmit the light with strong orientation from the light source too much. In a case where the light box  1  is thin, it needs to set the total light ray transmissivity to around 30%, because the light diffusion surface plate  26  above the light source becomes too bright and originates irregularities in the illuminating intensity if the brightness of the LED  4 , which is a light source, is as high as 15,000 cd/m 2 , which is the maximum value and the total light ray transmissivity of the light diffusion surface plate  26  is as high as 70% of the maximum value. In other words, it is advantageous if the total light ray transmissivity approaches to the lower limit when the brightness of the light source is high and the total light ray transmissivity approaches to the upper limit when the brightness of the light source is low. It is noted that the total light ray transmissivity is a value obtained according to JIS K 7105-1981. 
     As shown in  FIG. 2 , the top portion  22   a  of the receiving concave portion  22  locates at a location below or on a bisection point  27  of a distance from the emitting portion  4   a  of the LED  4  to the light diffusion surface plate  26  and above or on the emitting portion  4   a  of the LED  4 . 
     Hereinafter, the present invention will be described in detail with the Examples. However, the present invention is not limited to those examples. 
     Example 1 
     We made a light box  1  shown in  FIG. 1  and  FIG. 2 . 
     The case  2  is made as a planar rectangular shape, which has a longitudinal distance (inner measurement) of 300 mm, shown in the up-and-down directions in  FIG. 1 , and a lateral distance (inner measurement) of 400 mm, shown in the left and right directions in  FIG. 1 , and has an opening in the upper portion having a depth distance of 60 mm, shown in up-and-down directions in  FIG. 2 . The thickness distance of the bottom board  2   a  and the side board  2   b  is made 4 mm each. At the upper surface of the bottom board  2   a  of the case  2  (the inner surface of the bottom of the case  2 ), total twelve of the light source modules  3  with three in the longitudinal direction and four in the lateral direction, which forms a plurality of point like light sources, are arranged in a matrix shape with mutually-crossing intervals of 100 mm in the longitudinal direction and intervals of 100 mm in the lateral direction. 
     As for the light source module  3 , we used Shining Eye (L) (a product name made by Koha Co. Ltd.; Product No. FA003F001—Serial Circuit—Dedicated Power Source 0.3 W/pcs). 
     The brightness of the light source module  3  was 400 cd/m 2 , measured using a brightness meter when one of the light source module  3  was lightened and was spaced apart a distance L with the light diffusion surface plate  26  removed from the top portion  4   b  of the LED  4 . The brightness was measured using a brightness meter made by Topcon Corporation (Model Name: BM7), and spaced apart a distance L of 350 mm from the top portion  4   b  of the LED  4  to the measurement section BMa of the brightness meter BM, as shown in detail in  FIG. 2 . 
     The light reflecting plate  21  has a shape in which the receiving concave portions  22  having truncated reversed quadrangle pyramid shapes are connected continuously in the longitudinal and lateral directions at their top portions  22   a , and an insertion hole  23  is formed on the bottom of the receiving concave portion  22 , and the light flux control member  7  of the light source modules  3  projects from the insertion holes  23 . The top portion  22   a  of the truncated reversed quadrangle pyramid shape may be pushed together by the truncated reversed quadrangle pyramids. 
     The receiving concave portions  22  of the light reflecting plate  21  have truncated reversed quadrangle pyramid shapes, and their top portions  22   a  are successively connected with each other, and insertion holes  23  having circular shapes are opened at their bottom for inserting through the LEDs  4 . As for the size, the longitudinal distance of the upper part of the receiving concave portion  22  of the light reflecting plate  21  is 100 mm, its lateral distance is 100 mm, the longitudinal distance of the bottom is 54 mm, its lateral distance is 54 mm, its depth distance is 23 mm, and the diameter of the insertion holes  23  is 30 mm (the gap between itself and the light flux control member  7  is 3.5 mm). 
     As for the light diffusion surface plate  26 , Acrylite (a product name of Mitsubishi Rayon Co., Ltd.; Color No. #430) was used, which is a milky white colored acrylic resin board having a longitudinal distance of 308 mm, a lateral distance of 408 mm, and a thickness distance of 3 mm. The total light ray transmissivity of the light reflecting plate  21  was 30%. 
     Comparative Example 1 
     A light box was formed which was similar to Example 1 except that the light reflecting plate  21  was not used. The light source modules  3  of Comparative example 1 had a brightness of 400 cd/m 2  measured using a brightness meter when one of them was lightened and spaced apart a distance of 350 mm from its top. Note that the light was directly measured with the light diffusion surface plate  26  removed. 
     Comparative Example 2 
     A light box was formed with a case  2  and a light diffusion surface plate  26  having the same size with those of Example 1 but with changed inside point like light sources. 
     A circuit board was arranged at the bottom of the case  2  (at an upper surface of the bottom board  2   a ), in which point like light sources were arranged in an array at a longitudinal interval of 40 mm and a lateral interval of 40 mm. The point like light sources were used with 70 of them in a matrix with 7 in a longitudinal direction and 10 in the lateral direction. As for the point like light source, Nichia Corporation made LEDs (Product No.: NSPW510CS, Directionality: 50°) were used at a consumption power of 0.104 W/unit. Light dispersing means for the LEDs, such as concave lenses and prisms, or a light reflecting plate were not used. 
     Comparative Example 3 
     The point like light sources of Comparative example 2 were used with 130 of them in a matrix of 10 in a longitudinal direction and 13 in a lateral direction with intervals of 30 mm in a longitudinal direction and intervals of 30 mm in a lateral direction. 
     Thereafter, evaluations were done for Example 1 and Comparative examples 1-3, using the following method. 
     In the evaluation, the illumination intensity at 10 locations were measured by lighting the light sources of the light box  1  of the Example 1 in a dark room and directly contacting the light receiving section of an illumination meter to the light diffusion surface plate  26 . As for the illumination intensity measurement appliance, a General AA Class illumination intensity meter (model name 51002) made by Yokogawa Meters &amp; Instruments Corporation was used for the measurement. As for the 10 measurement locations on the light diffusion surface plate  26 , four locations above the light sources of the second row from the top were referred to as K 1 , K 2 , K 3 , and K 4 , three locations above between the light sources of the second row from the top were referred to as Y 1 , Y 2 , and Y 3 , and the three locations among the top region of the light reflecting plate  21  extending in the lateral direction between the light sources of the first row from the top and the light sources of the second row where it is crossed with the top region of the light reflecting plate  21  extending in the longitudinal direction were referred to as Y 4 , Y 5 , and Y 6 , and all of those locations were measured, respectively. Furthermore, the irregularities in the illumination intensity were observed with the visual observation from a location 3 m vertically spaced apart from the output surface. 
     The results for the measurement for Example 1 were 1104 lux at K 1 , 1120 lux at K 2 , 1124 lux at K 3 , 1105 lux at K 4 , 1101 lux at Y 1 , 1104 lux at Y 2 , 1103 lux at Y 3 , 1101 lux at Y 4 , 1100 lux at Y 5 , and 1105 lux at Y 6 . The irregularities in the illumination intensity were not observed with a visual observation from a location 3 m spaced apart in the dark room. 
     In contrast, the results for the measurement for Comparative example 1 were 1095 lux at K 1 , 1112 lux at K 2 , 1116 lux at K 3 , 1095 lux at K 4 , 812 lux at Y 1 , 812 lux at Y 2 , 814 lux at Y 3 , 801 lux at Y 4 , 810 lux at Y 5 , and 805 lux at Y 6 . Significant irregularities in the illumination intensity were observed with a visual observation from a location 3 m spaced apart in the dark room. 
     With regards to the light box of Comparative example 2, the average illumination intensity was 1004 lux, as a result of measuring the illumination intensity for all of the 70 locations above the point like light sources by lighting the light sources of the light box  1  of Comparative example 2 in the dark room and directly contacting the light receiving section of the illumination intensity meter to the light diffusion surface plate  26 . The average illumination intensity was 877 lux, as a result of measuring the illumination intensity at 54 locations of the center of the mutually adjacent four point like light sources (allocated at the four corners of the rectangular frame), that is, the intersecting points of between the rows and between the columns, such as the center of the total 4 light sources at the first row and the second row from the top and the first column and the second column from the left. Significant irregularities in the illumination intensity were observed with a visual observation from a location 3 m spaced apart in the dark room. 
     With respect to the light box of Comparative example 3, the average illumination intensity was 1540 lux, as a result of measuring at all of the 130 locations above the point like light sources by lighting the light sources of the light box  1  of Comparative example 3 in the dark room and directly contacting the light receiving section of the illumination intensity meter to the light diffusion surface plate  26 . The average illumination intensity was 1140 lux, as a result of measuring the illumination intensity for the 108 locations at the center of the mutually adjacent four point like light sources (allocated at the four corners of the rectangular frame), that is, the intersecting points of between the rows and between the columns, such as the center of the total four light sources at the first row and the second row from the top and the first column and the second column from the left. Significant irregularities in the illumination intensity were observed with a visual observation from a location 3 m spaced apart in the dark room. 
     Generally, requirements for the case where a light box is used for a facade signboard of a convenience store are that the surface illumination intensity at all of the locations at the surface of the light diffusion surface plate  26  exceeds 1000 lux, the ratio of the most bright location to the most dark location is within two, and there are no irregularities in the illumination intensity when visually observed them placed out of doors at the night. 
     Therefore, as is apparent from the above evaluation results, Example 1 fully satisfies the requirements for functioning as a facade signboard, whereas Comparative examples 1-3 could not satisfy the requirements for functioning as a facade signboard. 
       FIG. 6  and  FIG. 7  show a second embodiment of the light box  1  according to the present invention,  FIG. 6  is a partially-cut top view of the main part, and  FIG. 7  is a cross-sectional view of  FIG. 6 . Same numerals are assigned in the figure and the descriptions are omitted for identical or corresponding structures with the light box of the aforementioned first embodiment. 
     In the exemplary light box of the second embodiment, a plurality of point like light sources are arranged on the circuit board. 
     The light box  31  of the second embodiment includes a case  2  in which openings are formed in the direction of the light (upwards in  FIG. 7 ), as is with the light box  1  of the aforementioned first embodiment. 
     A circuit board  41  having a planer shape is arranged at the bottom of the case  2 . At the upper surface of the circuit board  41 , LEDs  42  which consists of a plurality of point like light sources are mounted, and more specifically, the LEDs  42  are formed by molding onto the point-type emitting portion  42   a  to form a bullet shape with the sealing member  42   b , such as epoxy resin and glass, to form LED lamps. These LEDs  42  are arranged in a matrix on the circuit board  41 , and more specifically, on the upper surface of the circuit board  41 , with the same intervals in the mutually crossing longitudinal and lateral directions. On the circuit board  41 , a light reflecting plate  43  for reflecting the light from the LEDs  42  is arranged to face the upper surface of the circuit board  41 . 
     The LEDs  42  as the point like light source of this second embodiment are formed such that the light emitting portion  42   a  is encapsulated by the sealing member  3   b  to be like the molded bombshell, and a light scatter means is provided for the sealing member  42   b  to cover the light emitting portion  42   a . By thus provided light scatter means, the illumination device is formed so that the brightness of one of the plurality of LEDs  42  is to be up to 15000 cd/m 2 , when the brightness is defined as that the incident angle of the light emitted from the LED is zero and 350 mm apart from the LED in a situation where a light diffusion surface plate  26  is detached (hereinafter simply referred to as the “brightness of LED  42 ”). In addition, the illumination device is formed so that a part or all of the light emitted from one of the LEDs  42  as the point like light source is reflected from the inner face of a receiving concave portion  45  described later of the light reflecting plate  43  to be scattered and supplied as the illumination. 
     Although the upper limit of the LED brightness is 15000 cd/m 2 , 2000 cd/m 2  is preferable. With the above described LED brightness, the glare of the light source looked from the direct beneath can be much reduced. The lower limit of the LED brightness is 100 cd/m 2 , 300 cd/m 2  is preferable. Even if the LED brightness is low, it is applicable that the light is scatter-reflected from the light reflecting plate  43  and widely pervaded in the horizontal direction. 
     When the sealing member  42   b  is formed by a transparent resin or glass, the light diffusion means is formed by the sealing member  42   b  with the surface blast-processed, the sealing member  42   b  with the surface etched, or the sealing member  42   b  in which the material forming the sealing member  42   b  is mixed with a scatter material such as light scattering glass. The etching in the present invention means a process to roughen the surface of the material, namely, a surface roughening treatment. As the method of etching, it can be appropriately selected depending on the material of the sealing member  42   b  in the followings: cutting, grinding, ultrasonic machining, laser such as excimer laser, electrical discharging machining, wet and dry etching, electron beam, sandblast, micro blast or the like. 
     The sealing member  42   b  may be formed to a prism type or concave lens type so that a part or all of the light from the light emitting portion  42   a  is scattered in the lateral direction of the sealing member  42   b.    
     The point like light source may be provided with a light flux control member (refer to reference numeral  7 ,  9  in  FIG. 3-5 ) to expand and emit the light from the point like light source. Preferably, the light flux control member may uniformly and smoothly expand the light from the point like light source and emit same. The light flux control member may have the shape to enable to expand the light emitted from the point like light source and emit same. For example, the light flux control member has a shape like a disk and the upper face of the upper portion of which looks like a partially defect sphere. In addition, the light flux control member may have a shape like a disk, the upper face of the upper portion of which looks like a partially defect sphere, and the end edge of the upper face of the upper portion of which has a smoothly curbed portion. Further, the light flux control member may have a shape like a disk, and the lower face of the upper portion of which looks like a partially defect sphere. The light flux control member may also have a shape looks like a disk, and the upper face of the upper portion of which has a cone-shaped concave portion with the bottom positioned in the center thereof. The light flux control member may also have a shape looks like a disk, the upper face of the upper portion of which has a parabolic concave curve from the peripheral border of the portion toward the bottom positioned in the center thereof. The light flux control member also may have a shape like a disk, the upper face of the upper portion of which has a sharp concave portion with the bottom positioned in the center thereof, and the side portion of the upper face of which has a respective square corners (refer to  FIG. 3 ). As an example of the above described light flux control member, LEC (Light Enhancer Cap: the product of Enplas Display Device Corporation) can be exemplified. The light flux control member may be arranged to cover the surface of the sealing member  42   b . In this case, the light flux control member may have a shape in which a concave portion is provided on the lower face to fix the sealing member  42   b  therein. 
     The kind and shape of the point like light source are not specifically limited, and can be selected among the above described bombshell type LED (LED  42 ), surface mounted type LED or the like. 
     As the color of the emitted light from the point like light source, various kind of color such as red, green, blue, yellow, white or the like can be used by itself or in combination with the other. 
     The brightness of the point like light source can be appropriately selected, considering the scope of the invention according to the conditions. 
     The number of the point like light source received in single receiving concave portion  45  may be one or plural. 
     The receiving concave portion  45  to enclose each of the plurality of LEDs  42  is formed by the circuit board  41  and the light reflecting plate  43 . The shape of the bottom of the receiving concave portion  45 , formed by the circuit board  41  is quadrangle in the embodiment, however, any shape is applicable. 
     As for the receiving concave portion  45 , as shown in  FIG. 8 , it may have a truncated reversed multi sided pyramid shape, that is, a shape having an insertion hole  46   a  in which an LED  42  formed at the center of the bottom of the receiving concave portion  45  can be freely inserted through. As for the shape of the insertion hole  46   a , it is typically a planar circle shape but it may be of any shape. 
     The receiving concave portion  45  of the second embodiment is formed in a reversed multi sided pyramid shape, more specifically, a reversed quadrangle pyramid shape, and the top portions  45   a  of the receiving concave portions  45  are arranged to locate in a same plane. The top portions  45   a  of the plurality of receiving concave portions  45  are preferably each connected to the top portion  45   a  of the adjacent receiving concave portion  45 . 
     More specifically, the light reflecting plates  43  are arranged to position between the LEDs  42 , or the light reflecting plates  43  are arranged to place each of the LEDs  42  in the respective receiving concave portions  45  formed to be the reversed multi-sided pyramid. 
     Therefore, the LEDs  42  are arranged and wired to the circuit board  41  in advance so that they project in the direction of the surface located at the opening side of the case  2  from the bottom of each of the receiving concave portions  45 . 
     As for the shape of the receiving concave portion  45 , it is not limited to a reversed quadrangle pyramid shape, and other reversed multi sided pyramid shapes, such as a reversed triangular pyramid shape, a reversed pentangular pyramid shape, and a reversed hexangular pyramid shape may be possible. Furthermore, as for the shape of the receiving concave portion  45 , it may be suitably selected according to the requirements, such as specifications and design concepts, from various shapes, such as a truncated reversed multi sided pyramid shape, a cup shape, a pot shape, a half sphere shape, a half ellipse sphere shape, comprising a through-hole at the bottom shown in  FIG. 8  that forms an insertion hole  46   a.    
     The apex angle of the top portion  45   a  of the receiving concave portion  45  formed in a truncated reversed quadrangle pyramid shape in the second embodiment is 60-120°, and more preferably, 80-100°. The height of the top portion  45   a  is greater than or equal to the height of the emitting portion  42   a  of the light source and is less than or equal to the height of a bisection point of a distance from the emitting portion  42   a  to the light diffusion surface plate  26 , and more preferably, less than or equal to the height of the bisection point and greater than or equal to the height of a trisection point. 
     A manufacturing method of the light reflecting plate  43  of the second embodiment will be described now with reference to  FIG. 9 . 
     As depicted in  FIG. 9 , the film or sheet is stamped out, and then bent at the center thereof along the longitudinal direction to form a mountain like member. First concave fitting portions  51   a  having the depth of a half of height are formed with a specific pitch at the top  45   a  of the mountain-like member toward the bottom in order to produce the first mountain like member  51 . In the same fashion, second concave fitting portions  52   a  having the depth of a half of height are formed with a specific pitch at the top  45   a  of the mountain like member toward the bottom in order to produce the second mountain like member  52 . The first concave fitting portions  51   a  and the corresponding second concave fitting portions  52   a  are fitted each other to form the light reflecting plate with a plurality of reverse four sided pyramid type of the receiving concave portions  45 . Furthermore, engaging members  53  protruding from the bottom are formed with a prescribed pitch at the bottom portion of the respective first and second mountain like member  51 ,  52 . The engaging member  53  may be inserted into the slit (not shown) formed in the circuit board  41  and fixed thereto. Of course, the film or sheet may be pressed like a food tray to integrally form the light reflecting plate. In this case, an apex portion  45   a  of the receiving concave portion  45  is connected to an apex portion  45   a  of an adjacent receiving concave portion, thus integrally formed. 
     As for other arrangements, they are similar to the aforementioned light box  1  according to the first embodiment and the detailed descriptions are omitted. 
     According to such light box  31  of the second embodiment, it was able to confirm similar advantageous effects to the aforementioned light box  1  according to the first embodiment. 
     In other words, according to the light box  31  of the second embodiment, similar to the aforementioned light box  1  according to the first embodiment, there are advantageous effects, such as suppressing the occurrence of the irregularities in the surface illumination intensity even with thin light boxes using light sources having a strong directionality of the light, such as LEDs  42 , and having the number of the LEDs  42  reduced to ¼ to 1/9 of the prior art. 
     The light box of the present invention can be used for a variety of articles, such as for ceiling illuminations, facade signboards, and backlights in liquid crystal televisions. 
     The present invention is not limited to the above-described embodiments and may be modified with a variety of modifications if necessary.