Patent Publication Number: US-7896514-B2

Title: Light emitting device and display device using same

Description:
TECHNICAL FIELD 
     The present invention relates to a large variety of light-emitting devices typified by a backlight device such as a liquid crystal display device, for example, also relates to a display device using the light-emitting device, and the like. 
     BACKGROUND ART 
     Recently, display devices such as liquid crystal display devices, typified by, for example, a liquid crystal display television and a liquid crystal display monitor, have adopted a backlight as a light-emitting device for emitting light from the back, side or the like of a display panel. As the backlight, there is what is called a direct-lighting type in which a light source is disposed on a plane surface beneath the liquid crystal panel (a rear surface), for example. In addition, what is called an edge-lighting type exists in which a light source is disposed on two or one side of a light guide plate made of a transparent resin so that light incident on the light guide plate is reflected by a reflector disposed on the back surface of the light guide plate, and illuminates, for example, the surface of a liquid crystal display panel. Here, the direct-lighting type has an advantage of securing high brightness, but has a disadvantage of difficulty in achieving a thinner backlight. On the other hand, the edge-lighting type has an advantage of achieving a thinner backlight than the direct-lighting type, but has a disadvantage of difficulty in obtaining uniformity in the luminance for a large display. 
     A fluorescent tube such as a hot-cathode fluorescent tube or a cold-cathode fluorescent tube is widely used as the above-mentioned backlight device. On the other hand, technologies of backlight devices using light-emitting diodes (LEDs), which are one type of solid-state light-emitting elements, as a light source, have been recently developed as a substitute for the backlight devices using the fluorescent tubes. 
     Here, the backlight device is generally provided with a reflection plate (a reflector) configured to reflect light emitted from, for example, the LED toward, for example, an observer. 
     The related art disclosed in a Patent Official Gazette includes a technique that involves: the provision of a light guide plate having a light exit surface, a reflecting surface and a light entrance surface; the provision of a bottom plate and a sidewall under the light guide plate; the disposition of plural light-emitting diodes on the bottom plate; and the use of the sidewall as the reflecting surface (see Patent Document 1, for example). This Patent Document discloses that a film, sheet or the like made of resin such as white PET (polyethyleneterephthalate) or formed by a plating deposition of metal such as silver or aluminum is used, giving a specular reflection or high-reflectivity function to the sidewall in order to reflect light emitted from the light-emitting diodes. 
     Also, another Patent Official Gazette discloses a light emitting device provided with a reflector adapted to direct light toward the top face of an optical component in order to improve light extraction efficiency (see Patent Document 2, for example). 
     Patent Document 1: Japanese Patent Application Laid Open Publication No. 2005-108675 
     Patent Document 2: Japanese Patent Application Laid Open Publication No. 2005-57266 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The light-emitting diodes (LEDs), as adopted here, for example, as the direct-lighting type backlight for the liquid crystal display panel, are arranged, for example, in rows (in two-dimensional arrays) on the underside of a casing to form a surface light source. Such rows (two-dimensional arrays) are often formed, for example, lengthwise and widthwise at predetermined spaced intervals. Then, a diffusion plate or a prism sheet is typically formed at a distance on the order of 1 to 5 cm from the light-emitting diodes (LEDs) in the direction of the liquid crystal display panel. 
     Then, when the light-emitting diodes (LEDs) are driven to emit light, the emitted light travels directly to the diffusion plate or bounces off the reflector (a reflecting sheet) and sent to the diffusion plate. Thereafter, the light undergoes irregular reflections in the diffusion plate, and then, the light rays travel through the prism sheet and thus the light rays perpendicularly enter the liquid crystal display panel. At this time, light beams emitted from different light-emitting diodes (LEDs) are mixed together in the space formed between the light-emitting diodes (LEDs) and the diffusion plate, and further undergo irregular reflections in the diffusion plate, so that their mixing is promoted. This makes luminance and chromaticity uniform. Also, the diffusion plate generally has high luminance in a portion directly above the light-emitting diodes (LEDs), and therefore, the degree of diffusion in this portion is enhanced by using the diffusion plate for improving uniformity in the luminance. 
     However, the conventional device having the surface light source has a problem as given below: the device is still high in luminance in the portion directly above the light-emitting diodes (LEDs), although the diffusion plate is provided and also disposed at a given distance from the light-emitting diodes (LEDs) in order to render the luminance and the chromaticity uniform, as mentioned above. In particular, the use of multi-color (e.g., RGB) light-emitting diodes (LEDs), rather than monochromatic light-emitting diodes (LEDs), for color mixing leads to a problem as given below: inadequate color mixing takes place, and, in some cases, an unevenness of color may possibly develop. Methods for reducing the occurrence of nonuniformity in the luminance or the unevenness of color include enhancing the degree of diffusion of the diffusion plate in the portion directly above the light-emitting diodes (LEDs), and providing a lighting curtain for partial light shielding; however, these approaches lead to a decrease in the efficiency of light utilization. Also, the methods include the approach of further increasing the distance between the light-emitting diodes (LEDs) and the diffusion plate; however, this approach leads to an increase in the thickness of the surface light source device. 
     The present invention has been made in order to address the above technological problems. An object of the present invention is to provide a light emitting device using a solid-state light-emitting element such as an LED, and, by using such a device, capable of reducing nonuniformity in the luminance to achieve uniformity in the luminance. 
     An other object of the present invention is to provide a light emitting device and a display device capable of contributing to any one of thickness reduction, weight reduction, and cost reduction of the devices. 
     Still another object of the present invention is to provide a light emitting device and a display device excellent in heat radiation characteristics. 
     Means for Solving the Problems 
     In order to attain the above objects, according to one feature of the present invention, there is provided a light emitting device such as a direct-lighting type backlight device for use in a display device, in which light emitted from a luminous source disposed directly under a liquid crystal display panel is laterally reflected to achieve good light diffusion and color mixing. That is to say, a light emitting device to which the present invention is applied has a mounting substrate, a plurality of solid-state light-emitting elements that are mounted on the mounting substrate and a reflector. The reflector is mounted on the mounting substrate, has a first surface and a second surface opposite to the first surface, causes the first surface to reflect light emitted from any one of the plurality of solid-state light-emitting elements, and causes the second surface to reflect light from an adjacent one of the plurality of solid-state light-emitting elements to the one of the plurality of solid-state light-emitting elements. 
     Here, the reflector has a mounting portion for mounting the reflector so as to face a surface of the mounting substrate, and a bending portion that is bent from the mounting portion to form the first surface and the second surface. 
     The reflector has the bending portion corresponding to each of the plurality of solid-state light-emitting elements. 
     Moreover, the first surface of the reflector is disposed vertically above each of the plurality of solid-state light-emitting elements, when the mounting substrate is taken as a horizontal surface and the plurality of solid-state light-emitting elements is arranged so as to emit light upward. Then, it is preferable, for example, in a point to be able to reduce the luminance directly above the light source. 
     According to another aspect of the present invention, a light emitting device to which the present invention is applied has amounting substrate, a solid-state light-emitting element that is mounted on the mounting substrate and a reflector. The reflector has a mounting portion for mounting the reflector so as to face a surface of the mounting substrate and a bending portion bent from the mounting portion and disposed in a location so as to directly receive and reflect light from the solid-state light-emitting element. In addition, the reflector reflects the light emitted from the solid-state light-emitting element. 
     The bending portion is formed by cutting and bending up a part of the reflector, and the mounting portion is formed from an uncut part of the reflector. The reflector is mounted on the surface of the mounting substrate directly or with a different material interposed in between. 
     Further, the bending portion of the reflector has a first surface that directly receives and reflects light emitted from any one of a plurality of the solid-state light-emitting elements, and a second surface that receives and reflects light emitted from another one of the plurality of solid-state light-emitting elements adjacent to the one of the plurality of solid-state light-emitting elements. 
     Furthermore, the bending portion of the reflector has a first surface that directly receives and reflects light emitted from solid-state light emitting elements in a first row of a plurality of the solid-state light-emitting elements, and a second surface that receives and reflects light emitted from solid-state light emitting elements in a second row in the plurality of solid-state light-emitting elements, the second row being adjacent to the first row. Then, it is excellent in a point to be able to simplify the structure of the reflector. 
     On the other hand, according to a further aspect of the present invention, there is provided a display device including a display panel that displays an image and a backlight that is disposed on a back side of the display panel and that irradiates the display panel with light from the back side of the display panel. The backlight has a plurality of solid-state light-emitting elements and a reflector. The reflector has a first surface and a second surface opposite to the first surface, causes the first surface to reflect light emitted from any one of the plurality of solid-state light-emitting elements, and causes the second surface to reflect light from an adjacent one of the plurality of solid-state light-emitting elements to the one of the plurality of solid-state light-emitting elements. 
     Here, the reflector has a mounting portion for mounting the reflector so as to face a surface of the mounting substrate, and a bending portion that is bent from the mounting portion to form the first surface and the second surface. 
     The reflector has the bending portion corresponding to each of the plurality of solid-state light-emitting elements. 
     The backlight further has a mounting substrate on which the plurality of solid-state light-emitting elements is mounted. The reflector covers the solid-state light emitting elements at least in a vertical direction from a surface of the mounting substrate, and forms the first surface and the second surface at a certain angle with respect to any one of the surface of the mounting substrate and a plane parallel to the mounting substrate. The certain angle particularly lies between 10 and 45 degrees inclusive. 
     The first surface and the second surface of the reflector are disposed corresponding to each of the plurality of solid-state light-emitting elements. The light reflected on the second surface is light emitted from the adjacent one of the plurality of solid-state light-emitting elements and reflected on a first surface of another reflector adjacent to the reflector. Then, even though color mixing occurs, for example, with double length (length of an optical path) for pitch between solid-state light-emitting elements adjacent to each other as a light source, this configuration is preferable in a point that the necessary length of an optical path is secured. 
     Moreover, the first surface of the reflector directly receives and reflects light from solid-state light-emitting elements in a certain row of the plurality of solid-state light-emitting elements. 
     Advantages Of The Invention 
     According to the present invention having the above-mentioned configuration, it is possible to reduce nonuniformity in the luminance and to achieve uniformity in the luminance with the light emitting device using a solid-state light-emitting element such as an LED. 
     BEST MODES FOR CARRYING OUT THE INVENTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an entire configuration of a liquid crystal display device to which an exemplary embodiment is applied. The liquid crystal display device to which the present exemplary embodiment is applied, as a direct lighting type backlight device (backlight)  10 , includes a backlight frame  11  that contains a light-emitting portion, and a LED substrate (mounting substrate)  12  as a substrate on which plural light-emitting diodes (LEDs) that are one type of a solid-state light-emitting element as a light-emitting source are arrayed. Moreover, the backlight device  10  includes, as a laminate of optical films, a diffusion plate  13  which is a transparent plate for scattering and diffusing light to equalize the lightness over the entire surface, and prism sheets  14  and  15  as a diffraction grating film that has a light collection effect to the front. A diffusion film may further be set on the diffusion plate  13 . The backlight device  10  includes a brightness improvement film  16  with a diffusion and reflection type, for improving the brightness. Furthermore, the liquid crystal display module  30  includes a liquid crystal panel  31  that is configured by two glass plates sandwiching liquid crystal in between, and polarization plates (polarization filters)  32  and  33  for restricting the oscillation of optical wave to a given direction, which are each laminated on each glass plate of the liquid crystal panel  31 . The liquid crystal display device includes peripheral members (not shown in the figure) such as an LSI (Large Scale Integration) for driving. 
     The liquid crystal panel  31  includes various components not shown in the figure. For example, the two glass plates have display electrodes, active elements such as a thin film transistor (TFT), liquid crystal, a spacer, sealant, an orientation film, a common electrode, a protective film, a color filter, and others, none of which is shown in the figure. 
     Incidentally, the structural unit of the backlight device  10  is selected in an arbitrary way. For example, the unit including only the backlight frame  11  with the LED substrate  12  may be called as the “backlight device (backlight)” and distributed so as not to include the laminate of the optical films such as the diffusion plate  13  and the prism sheets  14  and  15 . 
       FIG. 2  is a view for explaining a partial structure of the backlight device  10  as a light emitting device. In an instance shown in  FIG. 2 , a direct-lighting type backlight configuration is adopted in which light sources are disposed directly beneath the rear of the liquid crystal display module  30 . In this backlight configuration, LED chips are arrayed in such a manner that they are almost uniformly distributed over the entire rear surface of the liquid crystal display module  30 . This is different from what is called a side-lighting type in which light sources are placed along one or two sides of a light guide plate and uniform light on a plane surface is obtained by a reflecting plate, the light guide plate and the like. 
     The backlight frame  11  has a casing structure made of, for example, aluminum, magnesium, iron, or a metallic alloy including these materials. For example, a polyester film or the like having a high performance of reflecting white light adheres to the inside of the casing structure. It also functions as a reflector. The casing structure is composed of a rear portion corresponding to the size of the liquid crystal display module  30  and side portions enclosing the four sides of the rear portion. On the rear portion or the side portions, a heat sink configuration including a cooling fin for exhaust heat may be provided as necessary. 
     In the instance shown in  FIG. 2 , plural LED substrates  12  (eight as employed in  FIG. 2 ) are provided, and each of the LED substrates  12  is fixed to a backlight frame  11  by plural screws (not shown in the figure). Also, the LED substrates  12  are each provided with a reflector  50  having a configuration characteristic of the present exemplary embodiment. The reflector  50  is mounted on the LED substrates  12  so that the bending direction of a bending portion (to be described later) is the same. A double-sided tape, an adhesive, a solder reflow, a screw or the like is used for mounting of the reflector  50 . 
       FIG. 3  is a view of assistance in explaining the structure of the LED substrate  12  with the reflector  50  not mounted thereon. Plural light-emitting diodes (LEDs)  21  are mounted on the LED substrate  12  shown in  FIG. 3 , and each of them forms a package. Also, the LED substrate  12  is provided with a wiring circuit  22  for supplying a drive current to the light-emitting diodes (LEDs)  21 , and with penetration hole portions  24  for fixing of the screws. Further, the LED substrate  12  includes a terminal  25  for supplying the drive current to the light-emitting diodes (LEDs)  21 . The wiring circuit  22  is made of, for example, copper or a copper-base metal material, and the light-emitting diodes (LEDs)  21  mounted on the LED substrate  12  are electrically connected to the wiring circuit  22 . A surface on which the wiring circuit  22  is formed is given a white resist process, and a reflectance of, for example, 80% or more is ensured. Incidentally, the wiring circuit  22  shown in  FIG. 3  does not reflect actual wiring and is not necessarily accurate one. Also, for example, a wiring circuit disposed under a package of the light-emitting diodes (LEDs)  21  and the like is omitted from  FIG. 3 . 
     The plural light-emitting diodes (LEDs)  21  are formed out of red LEDs emitting red light, green LEDs emitting green light, and blue LEDs emitting blue light, and the red, green and blue (RGB) LEDs are disposed on the LED substrates  12  in accordance with a given rule. By mixing light beams from the RGB LEDs (or equivalently, color mixing), a light source having a wide range of color reproducibility can be achieved. Then, the plural LED substrates  12  are mounted on the backlight frame  11 , and thereby, the light-emitting diodes (LEDs)  21  are uniformly disposed in the overall backlight structure. This enables providing a backlight device capable of achieving uniform luminance and chromaticity, by using all of the light-emitting diodes (LEDs)  21  present on the backlight frame  11 . Incidentally, in the instance shown in  FIG. 2 , the plural LED substrates  12  are provided; however, one LED substrate  12  may be adopted on which all light-emitting diodes (LEDs)  21  to be used as the light source for the backlight are collectively formed. 
     Description will now be given with regard to the reflectors  50  mounted on the LED substrates  12 . 
       FIGS. 4A and 4B  are views showing examples of the reflector  50  to which the exemplary embodiment is applied. The reflector  50  shown in the figures is formed, for example, by processing a thin sheet of phosphor bronze of about 0.3 mm thick. Also, the reflector  50  may be made of a thin sheet of aluminum, magnesium, iron, a metallic alloy including these materials, or the like. The reflector  50  includes a mounting portion  51  for mounting the reflector  50  in a manner facing a surface of the LED substrate  12  being a mounting substrate, and a bending portion  52  forming first and second faces, to be described later, by cutting and bending the mounting portion  51 . An uncut portion is the mounting portion  51 . In the instance shown in  FIG. 4A , the bending portion  52  is provided for each set of light-emitting diodes (LEDs)  21 . On the other hand, in the instance shown in  FIG. 4B , the bending portion  52  is provided for each row. 
     Desirably, the bending portion  52 , after bent, has a reflectance of, for example, 90% or more on both surfaces (namely, the first and second surfaces to be described later). Also, the reflectors to be formed on both surfaces may be formed by a deposition of aluminum or the like; however, attachment of an aluminum tape may substitute for the deposition. Also, the reflectors may be formed by plating or by coating white ink. Preferably, a bending angle lies between 10 to 45 degrees, or more preferably, the bending angle is 45 degrees in order to improve reflection efficiency. A bending angle less than 10 degrees is not desirable because the reflection efficiency is reduced. On the other hand, it is preferable that the bending angle is reduced in order to reduce the thickness of the light emitting device. Therefore, the optimum angle is determined by the tradeoff between the thickness reduction of the device and the reflection efficiency. Incidentally, as described in detail later, the configuration is such that a part of each bending portion  52  of the reflector  50  covers the light-emitting diodes (LEDs)  21  disposed on the LED substrate  12  (as placed horizontally) vertically upward. 
       FIGS. 5A to 5C  are views showing other examples of the reflector  50 . These examples of the reflector  50  are adapted for the LED substrate  12  on which the 4 by 8 light-emitting diodes (LEDs)  21  are arranged, as distinct from the structure shown in  FIG. 3 .  FIG. 5C  shows a middle plate  53 , and the middle plate  53  is provided with middle plate hole portions  53   a  for passing light from the light-emitting diodes (LEDs)  21  when the middle plate  53  is mounted on the LED substrate  12 . Two plates shown in  FIG. 5A  or four plates shown in  FIG. 5B  may be laid on top of the middle plate  53  to form the reflector  50  having substantially the same function as the reflector  50  shown in  FIG. 4B . 
     More specifically, in  FIG. 5A , the plate is concavely bent at a predetermined angle so as to be provided with the bending portions  52  at both end sides of the bent plate, and with the mounting portion  51  at the center thereof. The mounting portion  51  is provided with hole portions  51   a  for passing light from the light-emitting diodes (LEDs)  21  when the mounting portion  51  is mounted on the LED substrate  12  with the middle plate  53  as a different member in between. Also, in  FIG. 5B , the plate is bent in an L shape at an internal angle of 135 degrees (180 degrees minus 45 degrees) to 170 degrees (180 degrees minus 10 degrees) to form the mounting portion  51  and the bending portion  52 . As in the case of  FIG. 5A , the mounting portion  51  is provided with hole portions  51   a  for passing light from the light-emitting diodes (LEDs)  21  when the mounting portion  51  is mounted on the LED substrate  12  with the middle plate  53  as the different member in between. 
     If the plate shown in  FIG. 5A  and the middle plate  53  shown in  FIG. 5C  are used to form the reflector  50 , two plates shown in  FIG. 5A  are used, and the mounting portions  51  shown in  FIG. 5A  are attached to the middle plate  53 , at an interval of a row of the middle plate  53  shown in  FIG. 5C , that is, attached every two rows. 
     If the plate shown in  FIG. 5B  and the middle plate  53  shown in  FIG. 5C  are used to form the reflector  50 , four plates shown in  FIG. 5B  are used, and the mounting portion  51  of each of the plates shown in  FIG. 5B  are attached to the middle plate  53  for each row. Here, the hole portions  51   a  and the middle plate hole portions  53   a  are aligned thereby to prevent cutoff of light from the light-emitting diodes (LEDs)  21  mounted on the LED substrate  12 . A double-sided tape, an adhesive, a solder reflow, vacuum brazing or the like is used for the bonding of the middle plate  53  shown in  FIG. 5C  and the plates shown in  FIG. 5A  or  5 B. 
     Incidentally, the plates shown in  FIG. 5A  or  5 B may be mounted directly on the LED substrate  12  without the use of the plate shown in  FIG. 5C . 
       FIGS. 6A and 6B  are partial sectional views each showing a state where the certain reflectors  50  are mounted on the LED substrate  12 .  FIG. 6A  shows an example where the light-emitting diodes (LEDs)  21  are mounted in a protruding relation on the LED substrate  12  as shown in  FIG. 3 .  FIG. 6B  shows an example where a substrate laminated reflector  26  is formed on a surface of the LED substrate  12 , and the light-emitting diodes (LEDs)  21  are disposed in an opening portion  27  of the substrate laminated reflector  26 . Then, the opening portion  27  is filled with a transparent resin, after the mounting of the light-emitting diodes (LEDs)  21 . The substrate laminated reflector  26  is made of, for example, a film made of resin such as white PET or a film formed by a plating deposition of metal such as silver or aluminum, or the like to impart a specular reflection or high-reflectivity function to the first and second surfaces. 
     In the instance shown in  FIG. 6A , the light-emitting diodes (LEDs)  21  protrude from the surface of the LED substrate  12 , and thus, a bending angle α of the bending portion  52  is relatively large. On the other hand, in the instance shown in  FIG. 6B , the light-emitting diodes (LEDs)  21  are mounted in the opening portion  27  of the substrate laminated reflector  26  of the LED substrate  12  and thus, a bending angle β of the bending portion  52  may be set small. 
     In the instances shown in  FIGS. 6A and 6B , each of the mounting portions  51  of the reflector  50  is mounted directly on the surface of the LED substrate  12 . Each of the bending portions  52  cut and bent up from the mounting portion  51  includes a first surface  52   a  and a second surface  52   b  having a front-rear relationship with the first surface  52   a . In any of the instances shown in  FIGS. 6A and 6B , when the light-emitting diodes (LEDs)  21  are arranged so as to emit light upward, provided that the LED substrate  12  is a horizontal surface, the bending portions  52  are located vertically above the light-emitting diodes (LEDs)  21 , and the first surfaces  52   a  face the light-emitting diodes (LEDs)  21 . Thereby, each of the first surfaces  52   a  directly reflects mainly light emitted from the light-emitting diode (LED)  21  directly under the first surface  52   a . On the other hand, each of the second surfaces  52   b  reflects light emitted from the light-emitting diodes (LED)  21  adjacent to the light-emitting diode (LED)  21  directly under the second surface  52   b  and reflected by the first surfaces  52   a  of the adjacent reflectors  50 , or the like. Reflection other than the above-mentioned reflection may possibly occur, depending on the bending angle of the reflector  50 , diffraction of light, or the like; however, the above-mentioned reflection behavior is mainly obtained. 
       FIG. 7  is a view showing a modified example of the reflector  50 . Each of the reflectors  50  shown in  FIG. 7  is provided with a middle portion  52   c  in the bending portion  52  bent from the mounting portion  51 . A cross section of the middle portion  52   c  extends in vertical direction provided that the LED substrate  12  is a horizontal surface, or equivalently, extends vertically from the mounting portion  51 . The middle portion  52   c  also has the above-mentioned first surface  52   a  and second surface  52   b , and has the above-mentioned reflection function. Accordingly, light reflected by the middle portion  52   c  is also effectively utilized. The provision of the middle portion  52   c  increases degree of freedom of selecting the bending angle of the bending portions  52  in design, even if the light-emitting diodes (LEDs)  21  are mounted so as to protrude from the surface of the LED substrate  12 . 
       FIGS. 8A and 8B  are views showing other modified examples of the reflector  50 . In the instance shown in  FIG. 8A , sidewall portions  51   b  formed by vertically bending the mounting portion  51  are provided on both sides (one of which is shown in  FIG. 8A ). In the present exemplary embodiment, the mounting portion  51  includes the sidewall portion  51   b , and the bending portion  52  is bent from the sidewall portion  51   b  of the mounting portion  51 . Likewise, in the instance shown in  FIG. 8B , sidewall portions  51   c  formed by vertically bending the mounting portion  51  are provided on both sides (one of which is shown in  FIG. 8B ). In the present exemplary embodiment, the mounting portion  51  includes the sidewall portion  51   c , and the bending portion  52  is bent from the sidewall portion  51   c  of the mounting portion  51 . The instance shown in  FIG. 8A  is different from that shown in  FIG. 8B  in the shape of the sidewall portions  51  band  51   c . In  FIG. 8A , the reflector  50  is in a floating state as viewed only in cross section, while, in  FIG. 8B , the bending portion  52  is formed continuously with the LED substrate  12  or the substrate laminated reflector  26 . 
       FIGS. 9A to 9D  are views of assistance in each explaining a state where another modified example of the reflector  50  is mounted on the LED substrate  12 , inclusive of the modified examples shown in  FIGS. 8A and 8B . FIGS.  9 A and  9 B show partial sectional views of the modified examples in states where the reflectors  50  shown in  FIGS. 8A and 8B  are mounted on the LED substrates  12 , respectively. The reflectors  50  are the same as described above in that each of the reflectors  50  has the first surface  52   a  and the second surface  52   b , and has the function of reflecting light emitted from the light-emitting diodes (LEDs)  21 . 
     In  FIGS. 9C and 9D , end bending portions  56  and  57  are provided on each end of the bending portions  52 . Bending the bending portion  52  upward as shown in  FIG. 9C  is preferable in that the luminance is improved. Bending the bending portion  52  laterally as shown in  FIG. 9D  is excellent in that the degree of color mixing is improved. Also in these instances, the reflectors  50  are the same as described above in that each of the reflectors  50  has the first surface  52   a  and the second surface  52   b , and has the function of reflecting light emitted from the light-emitting diodes (LEDs)  21 . 
     Description will now be given with regard to functions of the light emitting device to which the present exemplary embodiment is applied. Incidentally, herein after, the terms “above” and “lateral” will be adopted, assuming the light-emitting diodes (LEDs)  21  are arranged to emit light upward provided that the LED substrate  12  is a horizontal surface, as shown in  FIGS. 6A and 6B , regardless of the orientation of the light emitting device. 
     When a voltage is applied to the light-emitting diodes (LEDs)  21 , light emitted from the light-emitting diodes (LEDs)  21  is guided to the first surface  52   a  of the bending portion  52 , which is an inclined surface above, and is reflected, as shown, for example, by the arrows in  FIGS. 6A and 6B . Then, the reflected light is dispersed in a lateral direction in  FIGS. 6A and 6B . 
     The first surfaces  52   a  of the bending portions  52  are disposed above (vertically above) the light-emitting diodes (LEDs)  21 , and thus, for example, if a liquid crystal display module  30  is disposed above in  FIGS. 6A and 6B , light emitted from the light-emitting diodes (LEDs)  21  does not directly reach the liquid crystal display module  30 . For example, if red, green and blue LEDs are used as the light-emitting diodes (LEDs)  21 , lateral reflection increases the length of an optical path and thus yields adequate color mixing. As a result, good white light having little unevenness of color is provided to the liquid crystal display module  30 . 
     As described in detail above, in the present exemplary embodiment, when the light-emitting diodes (LEDs)  21  are disposed to emit light upward provided that the LED substrate  12  is a horizontal surface, the use of the reflector  50  as mentioned above allows lateral reflection of light emitted upward from the light-emitting diodes (LEDs)  21 . As a result, good color mixing is achieved, and also, the uniformity in the luminance and the thinner design of the light emitting device are achieved. Also, directly above the light source, the amount of light transmission can be reduced, and thus, when the light emitting device is used as the surface light source device or the like, the luminance directly above the light source can be reduced, thereby the nonuniformity in the luminance and the unevenness of color are suppressed. 
     Also, a light emitting device having high heat radiation characteristics and low cost can be provided, as compared to an instance where a reflecting film is formed on a light guide plate. Enhancement of this heat radiation effect permits improving response speed of the liquid crystal panel  31  (see  FIG. 1 ), for example, when the light emitting device is used as the backlight for a liquid crystal display device such as a liquid crystal display. When the reflector  50  is made of a thin sheet (a thin film), weight reduction is achieved. Further, elimination of resin such as the light guide plate allows weight reduction. Also, collectively mounting the reflectors  50  by solder reflow or the like yields an improvement in assembly characteristics and thus achieves cost reduction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an entire configuration of a liquid crystal display device to which an exemplary embodiment is applied; 
         FIG. 2  is a view for explaining a partial structure of the backlight device; 
         FIG. 3  is a view of assistance in explaining the structure of the LED substrate with the reflector not mounted thereon; 
         FIGS. 4A and 4B  are views showing examples of the reflector to which the exemplary embodiment is applied; 
         FIGS. 5A to 5C  are views showing other examples of the reflector to which the exemplary embodiment is applied; 
         FIGS. 6A and 6B  are partial sectional views each showing a state where the reflectors to which the exemplary embodiment is applied are mounted on the LED substrate; 
         FIG. 7  is a view showing a modified example of the reflector to which the exemplary embodiment is applied; 
         FIGS. 8A and 8B  are views showing other modified examples of the reflector; and 
         FIGS. 9A to 9D  are views of assistance in each explaining a state where another modified example of the reflector is mounted on the LED substrate. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS AND SIGNS 
       10  . . . backlight device (backlight),  11  . . . backlight frame,  12  . . . LED substrate (mounting substrate),  13  . . . diffusion plate,  14 ,  15  . . . prism sheets,  21  . . . light-emitting diode (LED),  26  . . . substrate laminated reflector,  27  . . . opening portion,  30  . . . liquid crystal display module,  31  . . . liquid crystal panel,  32 ,  33  . . . polarization plates (polarization filters),  50  . . . reflector,  51  . . . mounting portion,  51   b ,  51   c  . . . sidewall portions,  52  . . . bending portion,  52   a  . . . first surface,  52   b  . . . second surface,  52   c  . . . middle portion,  56 ,  57  . . . end bending portions.