Patent Publication Number: US-10763408-B2

Title: Backlight including light emitting module and light reflective members

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 16/039,197, filed on Jul. 18, 2018, which claims priority to Japanese Patent Application No. 2017-141924, filed on Jul. 21, 2017 and Japanese Patent Application No. 2017-195352, filed on Oct. 5, 2017, the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     The present disclosure relates to a light-emitting device, an integrated light-emitting device and a light-emitting module. 
     In recent years, a subadjacent-type surface light-emitting device using a semiconductor light-emitting device has been proposed in the art for use as a backlight of a display device such as a liquid crystal display device. In view of functionality, design, etc., a display device may be demanded to be thin, and a backlight is also demanded to be thinner. A light-emitting device of a general-purpose lighting application may also be demanded to be thin in view of functionality, design, etc. 
     Typically, when a light-emitting device of such an application is made thinner, brightness non-uniformity on the emission surface is likely to occur. Particularly, when a plurality of light-emitting elements are arranged in a one-dimensional or two-dimensional array, the brightness is higher directly above the light-emitting elements than in regions therearound. Therefore, PCT Publication WO2012/099145, for example, discloses a technique whereby light-emitting elements are encapsulated, and a diffusive member is partially arranged in the vicinity of the region directly above each light-emitting element on the surface of the resin member that functions as a lens, thereby improving the uniformity of light emitted from the light source. 
     SUMMARY 
     The present disclosure provides a light-emitting device whose brightness non-uniformity is suppressed. 
     A light-emitting device of the present disclosure includes: a base member having a conductive pattern; a light-emitting element arranged on the base member so as to be electrically connected to the conductive pattern; and a dielectric multi-layer film provided on an upper surface of the light-emitting element, wherein the dielectric multi-layer film has a first spectral reflectivity in an emission peak wavelength region of the light-emitting element and a second spectral reflectivity in a region that is located at a longer wavelength side by 50 nm than the emission peak wavelength region, and the second spectral reflectivity is greater by 10% or more than the first spectral reflectivity. 
     The present disclosure provides a light-emitting device having a wide spread of light distribution, in which brightness non-uniformity between regions directly above light-emitting elements and other regions therearound is suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view showing an example of a light-emitting device of a first embodiment. 
         FIG. 2  is a graph showing an example of a spectral reflection characteristic of a dielectric multi-layer film of the light-emitting device shown in  FIG. 1 . 
         FIG. 3  shows how light is emitted as seen through a diffuser plate, with an ordinary dielectric multi-layer film provided on the upper surface of a light-emitting element. 
         FIG. 4  is a graph showing the incident angle dependence of the spectral reflection characteristic of the dielectric multi-layer film. 
         FIG. 5  is a schematic diagram showing how light is emitted from a light-emitting element of the light-emitting device shown in  FIG. 1 . 
         FIG. 6A  is a cross-sectional view showing an example of a light-emitting module of a second embodiment. 
         FIG. 6B  is a top view showing an integrated light-emitting device of the light-emitting module shown in  FIG. 6A . 
         FIG. 7A  is a cross-sectional view showing an example of a backlight of a third embodiment. 
         FIG. 7B  is a cross-sectional view showing another example of a backlight of a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A light-emitting device, an integrated light-emitting device and a light-emitting module according to embodiments of the present disclosure will now be described with reference to the drawings. The light-emitting device, the integrated light-emitting device and the light-emitting module to be described below are each an example embodiment, and various modifications can be made to each embodiment. In the following description, terms representing specific directions or positions (e.g., “up/upper”, “down/lower”, “right”, “left”, and other terms including these words) may be used. These terms are used merely for the ease of understanding of relative directions/positions on the accompanying drawings. As long as the directional/positional relationship defined by terms such as “up/upper” and “down/lower” is consistent throughout the drawings, it does not need to coincide with the directional/positional relationship on drawings other than those of the present disclosure and in actual products, etc. The sizes of components, the positional relationships therebetween, etc., shown in the drawings may be exaggerated for the ease of understanding, and may not strictly reflect those of actual light-emitting devices. Note that some elements may be omitted in schematic cross-sectional views, etc., in order not to excessively complicate the drawings. 
     First Embodiment 
       FIG. 1  is a schematic diagram showing a cross-sectional structure of a light-emitting device  101  of the present embodiment. The light-emitting device  101  includes a base member  10 , a light-emitting element  21 , and a dielectric multi-layer film  22 . These components will now be described in detail. 
     [Base Member  10 ] 
     The base member  10  has an upper surface and supports the light-emitting element  21  thereon. The base member  10  supplies electric power to the light-emitting element  21 . The base member  10  includes a base material  11  and a conductive pattern  12 , for example. The base member  10  may further include an insulative layer  13 . 
     The base material  11  is made of a resin such as a phenol resin, an epoxy resin, a polyimide resin, a BT resin, polyphthalamide (PPA), polyethylene terephthalate (PET), a ceramic, or the like, for example. Among others, it is preferred to select an insulative resin in view of the cost and moldability. Alternatively, a ceramic may be selected as the material of the base material  11  in order to realize a light-emitting device having a good heat resistance and a good light resistance . Examples of the ceramic include alumina, mullite, forsterite, a glass ceramic, a nitride-based substance (e.g., AlN), a carbide-based substance (e.g., SiC), and the like, for example. Among these, it is preferred to use a ceramic made of alumina or a ceramic whose main component is alumina. 
     When a resin is used as the material of the base material  11 , the resin may be mixed with an inorganic filler such as glass fiber, SiO 2 , TiO 2  or Al 2 O 3  for purposes such as improving the mechanical strength, reducing the coefficient of thermal expansion, and improving the optical reflectivity. The base material  11  may be a composite plate including an insulative layer formed on a metal plate. 
     The conductive pattern  12  has a predetermined line pattern. The conductive pattern  12  is electrically connected to an electrode of the light-emitting element  21  so as to supply electric power from the outside to the light-emitting element  21 . The line pattern includes a positive electrode line connected to the positive electrode of the light-emitting element  21  and a negative electrode line connected to the negative electrode of the light-emitting element  21 . The conductive pattern  12  is formed at least on an upper surface of the base member  10 , on which the light-emitting element  21  is placed. The material of the conductive pattern  12  may be suitably selected from among conductive materials, depending on the material of the base material  11 , the production method of the base material  11 , etc. For example, when a ceramic is used as the material of the base material  11 , the material of the conductive pattern  12  is preferably a material having a high melting point such that it can withstand the sintering temperature of the ceramic sheet. The material of the conductive pattern  12  is preferably a high-melting metal such as tungsten or molybdenum, for example. A layer of another metal material such as nickel, gold or silver may be further provided by plating, sputtering, vapor deposition, etc., on the line pattern made of a high-melting metal as described above. 
     When a resin is used as the material of the base material  11 , the material of the conductive pattern  12  is preferably a material that is easily machinable. When an injection-molded resin is used, the material of the conductive pattern  12  is preferably a material that can be easily subjected to processes such as a punching process, an etching process and a bending process, and that has a relatively high mechanical strength. Specifically, it is preferred that the conductive pattern  12  is formed from a metal layer, a lead frame, or the like, of a metal such as copper, aluminum, gold, silver, tungsten, iron or nickel, or an iron-nickel alloy, phosphor bronze, iron-containing copper or molybdenum. The conductive pattern  12  may further include a layer of another metal material on the surface of the line pattern made of a metal. Although there is no particular limitation on this material, it may be a layer of silver only, a layer made of an alloy of silver and copper, gold, aluminum, rhodium, or the like, or a multi-layer structure using these materials, silver, and various alloys, for example. The layer of the other metal material may be formed by plating, sputtering, vapor deposition, or the like. 
     [Insulative Layer  13 ] 
     The base member  10  may include the insulative layer  13 . The insulative layer  13  is provided on the base material  11  of the base member  10  so as to cover portions of the conductive pattern  12  to which the light-emitting element  21 , etc., are connected. That is, the insulative layer  13  is electrically insulative, and covers at least a portion of the conductive pattern  12 . Preferably, the insulative layer  13  has light reflectivity. Because the insulative layer  13  has light reflectivity, it is possible to reflect light that is emitted from the light-emitting element  21  toward the base member  10 , thereby improving light extraction efficiency. Because the insulative layer  13  has light reflectivity, a portion of light emitted from the light source to be incident on a transparent laminate including a diffuser plate, a wavelength converting member, etc., that is reflected can also be reflected, thereby improving the light extraction efficiency. Light that is reflected by these base members also passes through the transparent laminate, and it is therefore possible to further suppress the brightness non-uniformity. 
     There is no particular limitation on the material of the insulative layer  13 , as long as it is an insulative material that little absorbs light emitted the light-emitting element  21 . For example, it may be a resin material such as epoxy, silicone, modified silicone, a urethane resin, an oxetane resin, acrylic, polycarbonate or polyimide. To provide light reflectivity to the insulative layer  13 , any of the resin materials of the insulative layer  13  listed above may contain a white filler, which is added to an underfill material to be described later. A white filler will be described later in detail. 
     [Light Emitting Element  21 ] 
     Any of light-emitting elements of various forms may be used as the light-emitting element  21  arranged on the base member  10 . The light-emitting element  21  is a light-emitting diode in the present embodiment. Any wavelength may be selected for light emitted from the light-emitting element  21 . For example, a blue or green light-emitting element may be a light-emitting element using a semiconductor such as a nitride-based semiconductor (In x Al y Ga 1-x-y N, 0≤X, 0≤Y, X+Y≤1), ZnSe or GaP. A red light-emitting element may be a light-emitting element using a semiconductor such as GaAlAs or AlInGaP. A semiconductor light-emitting device using a material other than those listed above may be used. One can select, as necessary, the composition, emission color and size of the light-emitting element, and the number of light-emitting elements to be used. 
     When the light-emitting element  21  includes a wavelength converting member, it is preferred that the light-emitting element  21  uses a nitride semiconductor (In x Al y Ga 1-x-y N, 0≤X, 0≤Y, X+Y≤1) emitting light of a short wavelength that is capable of efficiently exciting the wavelength converting material included in the wavelength converting member. One can select from among a variety of emission wavelengths depending on the material and crystal mix degree of the semiconductor layer. The light-emitting element  21  may include the positive electrode and the negative electrode on the same surface, or may include the positive electrode and the negative electrode on different surfaces. 
     The light-emitting element  21  includes a growth substrate and a semiconductor layer layered on the growth substrate. The semiconductor layer includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer sandwiched therebetween. The negative electrode and the positive electrode are electrically connected to the n-type semiconductor layer and the p-type semiconductor layer, respectively. The growth substrate may be a transparent sapphire substrate, or the like, for example. 
     The n-side electrode and the p-side electrode of the light-emitting element  21  are flip-chip bonded on the base member  10  via a connection member  23  therebetween. Specifically, the positive electrode and the negative electrode of the light-emitting element  21  are connected to a positive electrode line and a negative electrode line included in the conductive pattern  12  of the base member  10  via the connection member  23 . The light-extracting surface is a surface of the light-emitting element  21  that is opposite from a surface thereof where the n-side electrode and the p-side electrode are formed, i.e., an upper surface  21   a  of the light-emitting element  21 , which is the primary surface of the transparent sapphire substrate. In the present embodiment, in order to reduce the brightness directly above the light-emitting element  21 , the dielectric multi-layer film  22  is arranged on the upper surface  21   a.  Therefore, a lateral surface  21   c  of the light-emitting element  21  also serves substantially as the light-extracting surface. 
     [Connection Member  23 ] 
     The connection member  23  is formed from a conductive material. Specifically, the material of the connection member  23  may be an Au-containing alloy, an Ag-containing alloy, a Pd-containing alloy, an In-containing alloy, a Pb—Pd-containing alloy, an Au—Ga-containing alloy, an Au—Sn-containing alloy, an Sn-containing alloy, an Sn—Cu-containing alloy, an Sn—Cu—Ag-containing Alloy, an Au—Ge-containing alloy, an Au—Si-containing alloy, an Al-containing alloy, a Cu—In-containing alloy, a mixture of a metal and a flux, etc. 
     The connection member  23  may be any of those in a liquid form, a paste form or a solid form (a sheet form, a block form, a powder form, a wire form), and the selection can be made appropriately depending on the composition, the shape of the support, etc. The connection member  23  may be formed as a single member or a combination of some members. 
     [Underfill Member  24 ] 
     An underfill member  24  may be arranged between the light-emitting element  21  and the base member  10 . The underfill member  24  contains a filler for purposes such as efficiently reflecting light from the light-emitting element  21  and bringing the coefficient of thermal expansion close to the light-emitting element  21 . Because the lateral surface  21   c  of the light-emitting element  21  is also a light-extracting surface in the present embodiment, as shown in  FIG. 1 , it is preferred that the underfill member  24  does not cover the lateral surface  21   c.    
     The underfill member  24  includes, as the matrix, a material that little absorbs light from the light-emitting element. For example, it may be epoxy, silicone, modified silicone, a urethane resin, an oxetane resin, acrylic, polycarbonate, polyimide, or the like. 
     Using a white filler as the filler of the underfill member  24 , light is more likely to be reflected, and it is possible to improve the light extraction efficiency. It is preferred that the filler is an inorganic compound. White, as used herein, includes what appears to be white because of scattering when there is a refractive index difference between the filler and the material around the filler even if the filler itself is clear. 
     The reflectivity of the filler is preferably 50% or more, and more preferably 70% or more, with respect to light of the emission wavelength of the light-emitting element  21 . With these reflectivities, it is possible to improve the light extraction efficiency of the light-emitting device  101 . The particle size of the filler is preferably 1 nm or more and 10 μm or less. When the particle size of the filler is in this range, the resin fluidity as the underfill material improves, and the material to be the underfill member  24  can desirably fill even small gaps. Note that the particle size of the filler is preferably 100 nm or more and 5 μm or less, and more preferably 200 nm or more and 2 μm or less. The filler may be spherical or scale-shaped. 
     Specifically, examples of the filler material include oxides such as SiO 2 , Al 2 O 3 , Al(OH) 3 , MgCO 3 , TiO 2 , ZrO 2 , ZnO, Nb 2 O 5 , MgO, Mg(OH) 2 , SrO, In 2 O 3 , TaO 2 , HfO, SeO and Y 2 O 3 , nitrides such as SiN, AN and AlON, and fluorides such as MgF 2 . Any of these materials may be used alone or mixed with others. 
     [Dielectric Multi-Layer Film  22 ] 
     The dielectric multi-layer film  22  is a member (e.g., a half mirror) that allows a portion of the incident light to pass therethrough while reflecting another portion of the incident light. The dielectric multi-layer film  22  is provided on the upper surface  21   a  of the light-emitting element  21 . With such a configuration, a portion of the light exiting through the upper surface  21   a  of the light-emitting element  21  is reflected by the dielectric multi-layer film  22  back into the light-emitting element  21  so as to exit through the lateral surface  21   c  of the light-emitting element  21 . As a result, the amount of light to exit through the upper surface  21   a  of the light-emitting element  21  is reduced and the brightness directly above the light-emitting element  21  is lowered, thereby suppressing the brightness non-uniformity in cases in which light-emitting devices  101  are used to make a backlight, or the like. Note however that with a dielectric multi-layer film having a typical spectral reflection characteristic provided on the upper surface  21   a  of the light-emitting element  21 , when light emitted from the light-emitting device  101  is observed through a diffuser plate, the brightness is higher in regions around regions that are directly above the light-emitting elements if the distance between the diffuser plate and the light-emitting element is short, as will be described later. That is, brightness non-uniformity is likely to occur. 
     In order to suppress such brightness non-uniformity, the dielectric multi-layer film  22  has a spectral reflectivity characteristic that includes at least two regions of different spectral reflectivities in the reflection wavelength band.  FIG. 2  shows, by a solid line, a schematic spectral reflectivity characteristic of the dielectric multi-layer film  22 .  FIG. 2  also shows a schematic example of an emission spectrum of light emitted from the light-emitting element  21 . 
     The dielectric multi-layer film  22  has a spectral reflectivity characteristic such that the spectral reflectivity (second spectral reflectivity) in the region R L , which is on the longer wavelength side of the emission peak wavelength region R E  of the light-emitting element  21  by 50 nm, is greater by 10% or more than the spectral reflectivity (firat spectral reflectivity) in the emission peak wavelength region R E  of the light-emitting element  21 . Herein, the spectral reflectivity is a value for vertically incident light. The emission peak wavelength region R E  is a wavelength region of a predetermined width centered about the peak wavelength λ p  of the light-emitting element  21 . For example, it is a wavelength region of λ E1  or more and λ E2  or less (λ E1 &lt;λ E2 ). The band of the emission peak wavelength region R E  is determined depending on the characteristics of light emitted from the light-emitting element  21 . For example, when the light-emitting element  21  is an LED emitting blue light, the band of the emission peak wavelength region R E  may be λ p ±20 nm. 
     The region R L  is a region that includes a region whose upper limit and lower limit are on the longer wavelength side of the upper limit and the lower limit by 50 nm, respectively, of the emission peak wavelength region R E . Specifically, the region R L  is a wavelength region of (λ E1 +50) nm or more and (λ E2 +50) nm or less. The spectral reflectivity in the region R L  being greater, by 10% or more, than the spectral reflectivity in the emission peak wavelength region R E  means that the spectral reflectivity at any wavelength in the region R L  is greater, by 10% or more, than the maximum spectral reflectivity in the emission peak wavelength region R E . The spectral reflectivity in the emission peak wavelength region R E  is 70% or more and 95% or less, and the spectral reflectivity in the region R L  is 80% or more and less than 100%. The emission peak wavelength region R E  and the region R L  do not overlap each other. 
     The reflection wavelength band B upon vertical incidence is defined as a region that includes the emission peak wavelength region R E  and the region R L  and in which the spectral reflectivity is 50% or more. The reflection wavelength band B of the dielectric multi-layer film  22  includes the emission peak wavelength of the light-emitting element, and the band B L  on the longer wavelength side of the emission peak wavelength is wider than the band Bs on the shorter wavelength side thereof. 
     The dielectric multi-layer film  22  is transparent and has a dielectric multi-layer film structure in which a plurality of dielectric layers having different refractive indices are layered together. The material of each dielectric layer is preferably a material that absorbs little light in the wavelength range emitted from the light-emitting element  21 , e.g., a metal oxide film, a metal nitride film, a metal fluoride film or an organic material. An organic layer such as a silicone resin or a fluororesin may be used as each dielectric layer. 
     The spectral reflectivity characteristics of the dielectric multi-layer film  22  (specifically, the positions of the emission peak wavelength region R E  and the region R L , the spectral reflectivity thereof, etc.) can be set to any characteristics by adjusting the thickness of the dielectric layer, the refractive index thereof, the number of layers, etc. The spectral reflectivity, etc., of the emission peak wavelength region R E  and those of the region R L  can be designed separately from each other. 
     [Encapsulation Member  30 ] 
     The light-emitting device  101  may include an encapsulation member  30 . The encapsulation member  30  protects the light-emitting element  21  from the ambient environment, and optically controls the distribution characteristic of the light output from the light-emitting element  21 . That is, the light emission direction is adjusted based primarily on the refraction of light through the outer surface of the encapsulation member  30 . The encapsulation member  30  is arranged on the base member  10  covering the light-emitting element  21 . 
     The surface of the encapsulation member  30  has a curved surface protruding upward. The encapsulation member  30  preferably has a circular or elliptical outer shape as seen from above. For the encapsulation member  30 , the ratio H/W between the height H in the optical axis L direction and the width W as seen from above is preferably less than 0.5. More preferably, H/W is 0.3 or less. The height H of the encapsulation member  30  is defined by the distance in the optical axis L direction from the mounting surface of the base member  10  to the highest portion of the encapsulation member  30 . The width W is based on the shape of the bottom surface of the encapsulation member  30 . The width W is defined as the diameter when the bottom surface is circular, and as the shortest width across the bottom surface when the bottom surface has any other shape. For example, when the outer shape as seen from above is an elliptical shape, the width W is defined as the short axis (between the long axis and the short axis) of the bottom surface. 
     When the encapsulation member  30  has such a shape, light emitted from the light-emitting element  21  refracts through the interface between the encapsulation member  30  and the air, and it is possible to increase the spread of the light distribution. 
     The material of the encapsulation member  30  may be a transparent resin such as an epoxy resin or a silicone resin, or a mixed resin thereof, or a glass, etc. Among others, a silicone resin is preferably selected for its light fastness and moldability. 
     The encapsulation member  30  may include a wavelength converting material and a light diffuser for diffusing light from the light-emitting element  21 . It may also include a colorant corresponding to the emission color of the light-emitting element. The wavelength converting material, the light diffusing material, the colorant, etc., are preferably contained in the encapsulation member  30  in such amounts that the light distribution can be controlled based on the outer shape of the encapsulation member  30 . In order to suppress the influence on the light distribution characteristic, the particle size of each material to be contained is preferably 0.2 μm or less. Note that the particle size, as used herein, means the average particle size (median diameter), and the value of the average particle size can be measured by a laser diffraction method. 
     [Emission and Effects of Light-Emitting Device  101 ] 
     In the light-emitting device  101 , the dielectric multi-layer film  22  is provided on the upper surface  21   a  of the light-emitting element  21 . With such a configuration, a portion of the light exiting through the upper surface  21   a  of the light-emitting element  21  is reflected by the dielectric multi-layer film  22  back into the light-emitting element  21  so as to exit through the lateral surface  21   c  of the light-emitting element  21 . As a result, this reduces the amount of light to exit through the upper surface of the light-emitting element  21  and lowers the brightness directly above the light-emitting element  21 , thereby suppressing the brightness non-uniformity in cases in which light-emitting devices  101  are used to make a backlight, or the like. 
     However, as a result of a study by the present inventor, it has been found that when a dielectric multi-layer film is provided on the upper surface of the light-emitting element and a diffuser plate, or the like, is arranged on the emission side of the light-emitting device to form a backlight, the brightness in the vicinity of the region directly above the light-emitting element becomes lower than the brightness therearound if the gap between the diffuser plate and the light-emitting element is short.  FIG. 3  shows how light is emitted as seen through a diffuser plate, with an ordinary dielectric multi-layer film, i.e., a dielectric multi-layer film that does not have the spectral characteristic of the dielectric multi-layer film  22 , provided on the upper surface of the light-emitting element. It is believed that, if the interval OD (see  FIG. 5 ) between the diffuser plate and the light-emitting element is short, light that vertically exits through the upper surface of the light-emitting element primarily reaches the region directly above the light-emitting element, whereas light that is reflected by the dielectric multi-layer film to exit through the lateral surface of the light-emitting element is unlikely to reach there. In other words, when a dielectric multi-layer film is provided on the upper surface  21   a  of the light-emitting element  21 , the brightness is higher in regions around regions that are directly above the light-emitting elements, thus causing brightness non-uniformity. If the reflectivity of the dielectric multi-layer film is lowered, the brightness in regions directly above the light-emitting elements increases, but the brightness in regions therearound also increases, failing to substantially reduce the brightness non-uniformity. 
     In the light-emitting device  101  of the present disclosure, the incident angle dependence of the spectral reflection characteristic of the dielectric multi-layer film is utilized so as to suppress the brightness non-uniformity described above. Typically, the spectral reflection characteristic of a dielectric multi-layer film varies between when light is incident vertically on the dielectric multi-layer film and when light is incident diagonally. When light is incident diagonally, as compared with when light is incident vertically, the optical path length increases, and the reflection wavelength band shifts toward the short wavelength side. This characteristic is also referred to as blue shift.  FIG. 4  is a graph schematically showing an example of the spectral reflection characteristic of the dielectric multi-layer film, wherein the solid line represents the spectral reflection characteristic with respect to vertically incident light, and the broken line represents the spectral reflection characteristic with respect to light that is incident from a direction inclined by 45° from the vertical direction. While the reflection wavelength band with respect to vertically incident light is about 430 nm to about 550 nm, the reflection wavelength band with respect to incident light inclined by 45° is 350 nm to 500 nm. The amount of shift of the spectral reflection characteristic toward the short wavelength side is about 40 nm at about 400 nm, and about 80 nm at about 700 nm. 
     As shown in  FIG. 4 , with an ordinary dielectric multi-layer film, the spectral reflectivity is substantially constant in the reflection wavelength band. However, the dielectric multi-layer film  22  used in the light-emitting device  101  of the present disclosure has a spectral reflectivity characteristic that includes the emission peak wavelength region R E  and the region R L  having different spectral reflectivities in the reflection wavelength band, as shown in  FIG. 2 . Thus, light beams with the same peak wavelength can be reflected with different spectral reflectivities depending on the incident angle. 
       FIG. 2  schematically shows an example of a reflectivity characteristic of the dielectric multi-layer film  22  in the light-emitting device  101  of the present embodiment. The solid line represents the spectral reflection characteristic of vertically incident light, and the broken line represents the reflection characteristic with respect to light that is incident from a direction inclined by 45° from the vertical direction. In the example shown in  FIG. 2 , the emission peak wavelength of the light-emitting element  21  is about 450 nm, and the emission peak wavelength region R E  is 430 nm to 470 nm. The region R L  is 480 nm to 520 nm. The spectral reflectivity in the emission peak wavelength region R E  is about 75%, and the spectral reflectivity in the region R L  is about 92%. That is, light that is vertically incident on the dielectric multi-layer film  22  is reflected with a spectral reflectivity of about 75%, but light that is diagonally incident on the dielectric multi-layer film  22  is reflected with a spectral reflectivity of about 92% at maximum. 
     As a result of an in-depth study, it has been found that with a light-emitting element  21  that emits blue light, for example, if the amount of shift is set to 50 nm, it is possible to increase the brightness in the region directly above the light-emitting element  21  while lowering the brightness in regions therearound, thereby efficiently reducing the brightness non-uniformity. 
       FIG. 5  schematically shows how light emitted from the light-emitting device  101  travels to reach a diffuser plate  51 . When the distance OD between the light-emitting element  21  and the diffuser plate  51  is short, a region  51   a  of the diffuser plate  51  that is directly above the light-emitting element  21  primarily receives light  23   a  that exits through the upper surface  21   a  of the light-emitting element  21  to be vertically incident on and pass through the dielectric multi-layer film  22 , as shown in  FIG. 5 . In contrast, a region  51   b  around the region  51   a  receives light  23   b  that is diagonally incident on and passes through the dielectric multi-layer film  22  and light  23   e  that exits through the lateral surface  21   c.  As described above, when passing through the dielectric multi-layer film  22 , the spectral reflectivity is 75% for light  23   a,  whereas the spectral reflectivity is 92% for light  23   b.  Therefore, more light  23   b  reaches the diffuser plate  51  than light  23   a,  thereby relatively increasing the brightness in the region  51   b  of the diffuser plate  51  and decreasing the brightness in the region  51   a.  Thus, light emitted from the light-emitting element  21  having the dielectric multi-layer film  22  can have, along a plane including the optical axis L, a batwing-shaped light distribution characteristic having a small brightness difference between the central portion and the peripheral portion. A batwing-shaped light distribution characteristic is generally defined as an emission intensity distribution such that the emission intensity is higher at a light distribution angle whose absolute value is greater than 0°, 0° being the optical axis L. Particularly, in a specific sense, it is defined as an emission intensity distribution such that the emission intensity is highest around 45° to 90°. 
     With the provision of the dielectric multi-layer film  22  described above, the light-emitting device  101  lowers the brightness in the region directly above the light-emitting element  21  and reduces the brightness non-uniformity. This means that the spread of the light distribution for light emitted from the light-emitting device  101  is increased, i.e., more light is emitted even at low angles. For example, 25% or more of the total amount of light emitted from the light-emitting device  101  of the present disclosure can be emitted at elevation angles of less than 20° with respect to the upper surface of the base member  10 . 
     By forming the encapsulation member  30  so that the outer shape thereof is a curved surface protruding upward and making the height-to-width ratio H/W less than 0.5, it is possible to increase the spread of the light distribution for light emitted from the light-emitting element  21 . For example, if the ratio H/W of the height H to the width W of the encapsulation member  30  is set to 0.3 or less, 40% or more of the total amount of light emitted from the light-emitting device  101  can be emitted at elevation angles of less than 20° with respect to the upper surface of the base member  10 . Thus, with these two configurations, it is possible to realize an intended light distribution characteristic without using a secondary lens. That is, with the provision of the dielectric multi-layer film  22 , it is possible to reduce the brightness directly above the light-emitting element  21 . Therefore, the encapsulation member  30  can be provided with the primary function of increasing the spread of the light distribution for light emitted from the light-emitting element  21 . Thus, it is possible to significantly reduce the size of the encapsulation member  30  having a lens function. Therefore, using the light-emitting device  101 , it is possible to realize a thin backlight module (light-emitting module) with improved brightness non-uniformity. 
     With conventional light-emitting devices, the encapsulation member is provided with the function of reducing the brightness directly above the light-emitting element and the function of increasing the spread of the light distribution. Therefore, it is necessary to provide an encapsulation member that has a relatively large outer shape and that functions also as a secondary lens, for example. 
     Second Embodiment 
       FIG. 6A  is a schematic diagram showing a cross-sectional structure of a light-emitting module  102  of the present embodiment. The light-emitting module  102  includes a transparent laminate  50  and an integrated light-emitting device  103 .  FIG. 6B  is a top view of the integrated light-emitting device  103 . 
     The integrated light-emitting device  103  includes the base member  10 , a plurality of light-emitting elements  21  arranged on the base member  10 , and the dielectric multi-layer film  22  provided on the upper surface of each light-emitting element  21 . The structure of the base member  10 , the light-emitting element  21  and the dielectric multi-layer film  22 , and the relationship between these components are as described above in the first embodiment. 
     The plurality of light-emitting elements  21  are arranged in a one-dimensional or two-dimensional array on an upper surface  11   a  of the base member  10 . In the present embodiment, the plurality of light-emitting elements  21  are arranged in two directions perpendicular to each other, i.e., arranged in a two-dimensional array along the x direction and the y direction, wherein the pitch px thereof in the x direction and the pitch py thereof in the y direction are equal to each other. However, the directions of arrangement are not limited thereto. The pitch in the x direction and the pitch in the y direction may be different from each other, and the two directions of arrangement may not be perpendicular to each other. The pitch does is not limited to a regular pitch, but rather may be an irregular pitch. For example, the light-emitting elements  21  may be arranged so that the pitch therebetween gradually increases from the center toward the periphery of the base member  10 . 
     The integrated light-emitting device  103  may include a plurality of light reflective members  15  located between the light-emitting elements  21 . The light reflective member  15  includes wall portions  15   ax  and  15   ay,  and a bottom portion  15   b.  As shown in  FIG. 6B , the wall portion  15   ay  extending in the y direction is arranged between two light-emitting elements  21  adjacent to each other in the x direction, and the wall portion  15   ax  extending in the x direction is arranged between two light-emitting elements  21  adjacent to each other in the y direction. Therefore, each light-emitting element  21  is surrounded by two wall portions  15   ax  extending in the x direction and two wall portions  15   ay  extending in the y direction. The bottom portion  15   b  is located in a region  15   r  that is surrounded by two wall portions  15   ax  and two wall portions  15   ay.  In the present embodiment, because the pitch of the light-emitting elements  21  in the x direction is equal to that in the y direction, the outer shape of the bottom portion  15   b  is square. A through hole  15   e  is provided in the center of the bottom portion  15   b,  and the bottom portion  15   b  is located on the insulative layer  13  so that the light-emitting element  21  is located in the through hole  15   e.  There is no particular limitation on the shape and size of the through hole  15   e  as long as the shape and size are such that the light-emitting element  21  can be located therein. It is preferred that the outer edge of the through hole  15   e  is located in the vicinity of the light-emitting element  21 , i.e., the gap between the through hole  15   e  and the light-emitting element  21  as seen from above is small, so that light from the light-emitting element  21  can also be reflected by the bottom portion  15   b.    
     As shown in  FIG. 6A , along the yz cross section, the wall portion  15   ax  includes a pair of inclined surfaces  15   s  extending in the x direction. The pair of inclined surfaces  15   s  are connected together along one of the two edges thereof extending in the x direction, thereby forming a top portion  15   c.  The other edge of each of the pair of inclined surfaces  15   s  is connected to the bottom portion  15   b  located in the corresponding one of the two adjacent regions  15   r.  Similarly, the wall portion  15   ay  extending in the y direction includes a pair of inclined surfaces  15   t  extending in the y direction. The pair of inclined surfaces  15   t  are connected together along one of the two edges thereof extending in the y direction, thereby forming a top portion  15   c.  The other edge of each of the pair of inclined surfaces  15   t  is connected to the bottom portion  15   b  located in the corresponding one of the two adjacent regions  15   r.    
     The bottom portion  15   b,  two wall portions  15   ax  and two wall portions  15   ay  together form a light-emitting space  17  having an opening therein.  FIG. 6B  shows light-emitting spaces  17  arranged in an array of three rows and three columns. The pair of inclined surfaces  15   s  and the pair of inclined surfaces  15   t  are facing the opening of the light-emitting space  17 . 
     The light reflective member  15  has a light reflectivity, and reflects light emitted from the light-emitting element  21  toward the opening of the light-emitting space  17  by means of the inclined surfaces  15   s  and  15   t  of the wall portions  15   ax  and  15   ay.  Light incident on the bottom portion  15   b  is also reflected toward the opening of the light-emitting space  17 . Thus, light emitted from the light-emitting element  21  can be made to enter the transparent laminate  50  efficiently. 
     The light-emitting spaces  17  partitioned by the light reflective members  15  is the minimum unit of light-emitting space when the plurality of light-emitting elements  21  are driven independently. It is the minimum unit area of local dimming when the upper surface of the transparent laminate  50  of the light-emitting device  101  is observed as a surface light emission source. When the plurality of light-emitting elements  21  are driven independently, a light-emitting device is realized that can be driven with local dimming by the smallest unit of light-emitting space. Local dimming by a larger unit can be realized by simultaneously driving a plurality of light-emitting elements  21  adjacent to each other by syncing ON/OFF thereof. 
     The light reflective member  15  may be formed by using a resin containing a reflective material that is made of particles of a metal oxide such as titanium oxide, aluminum oxide or silicon oxide, or it may be formed by using a resin containing no reflective material and then providing a reflective material on the surface. The reflectivity of the light reflective member  15  with respect to light emitted from the light-emitting element  21  is preferably 70% or more, for example. 
     The light reflective member  15  can be formed by molding using a mold or stereolithography. The molding method using a mold may be a molding method such as an injection molding, an extrusion molding, a compression molding, a vacuum molding, a pressure molding or a press molding. For example, by vacuum molding using a reflective sheet made of PET, or the like, it is possible to obtain the light reflective member  15  including the bottom portion  15   b  and the wall portions  15   ax  and  15   ay  formed integral together. The thickness of the reflective sheet is 100 μm to 500 μm, for example. 
     The lower surface of the bottom portion  15   b  of the light reflective member  15  and the upper surface of the insulative layer  13  are secured together via an adhesive member, or the like. The insulative layer  13  exposed through the through hole  15   e  preferably has a light reflectivity. It is preferred that an adhesive member is arranged around the through hole  15   e  so that light emitted from the light-emitting element  21  does not enter between the insulative layer  13  and the light reflective member  15 . For example, an adhesive member is preferably arranged in a ring shape along the outer edge of the through hole  15   e.  The adhesive member may be a double-sided adhesive tape, a hotmelt-type adhesive sheet, or an adhesive liquid of a thermosetting resin or a thermoplastic resin. Preferably, these adhesive members are highly flame-retarded. Instead of an adhesive member, the securing can be done by using other attachment members such as screws and pins. 
     Each region Ru surrounded by a plurality of light reflective members  15  can be regarded as one light-emitting device  101  having the light-emitting element  21 . That is, the integrated light-emitting device  103  includes a plurality of light-emitting devices  101  arranged at the pitch Px in the x direction and at the pitch Py in the y direction. 
     The height HR of the light reflective member  15  is preferably less than or equal to 0.3 time, and more preferably less than or equal to 0.2 time, the pitch of the light-emitting device  101 . When the light-emitting devices  101  are arranged in a two-dimensional array, the pitch is the shorter one of the two pitches in the two directions. Because the pitch px in the x direction is equal to the pitch py in the y direction in the present embodiment, the height HR is less than or equal to 0.3 times Px and Py, i.e., HR≤0.3Px or HR≤0.3Py. As the height HR of the light reflective member  15  satisfies this condition, it is possible to shorten the distance between the transparent laminate  50  and the integrated light-emitting device  103  and realize a thin light-emitting module. 
     The transparent laminate  50  is arranged on the light-extracting surface side of each light-emitting device  101  of the integrated light-emitting device  103 , i.e., on the upper surface side of the light-emitting element  21  of the base member  10 . The transparent laminate  50  may be in contact with, or spaced apart from, the light reflective member  15 . The transparent laminate  50  includes the diffuser plate  51  and a wavelength converting member  52 . 
     The diffuser plate  51  allows incident light to pass therethrough while diffusing the light. The diffuser plate  51  is formed from a material that little absorbs visible light, such as a polycarbonate resin, a polystyrene resin, an acrylic resin or a polyethylene resin, for example. A light-diffusing structure is provided in the diffuser plate  51  by providing protrusions/depressions on the surface of the diffuser plate  51  or dispersing a material having a different refractive index in the diffuser plate  51 . The diffuser plate  51  may be any of those on the market under the names “light diffusing sheet” or “diffuser film.” 
     The wavelength converting member  52  is located on one of the two primary surfaces of the diffuser plate  51  that is opposite from the surface facing the light-emitting device  101 . The wavelength converting member  52  absorbs a portion of light emitted from the light-emitting device  101  and emits light of a wavelength that is different from the wavelength of the light emitted from the light-emitting device  101 . 
     Because the wavelength converting member  52  is spaced apart from the light-emitting element  21  of the light-emitting device  101 , it is possible to use a light conversion material that is less resistant to heat and light, which is difficult to employ in the vicinity of the light-emitting element  21 . Therefore, it is possible to improve the performance of the light-emitting device  101  as a backlight. The wavelength converting member  52  has a sheet shape or a layer shape, and includes a wavelength converting substance. 
     Examples of the wavelength converting substance include a cerium-activated yttrium aluminum garnet (YAG)-based phosphor, a cerium-activated lutetium aluminum garnet (LAG), a europium- and/or chromium-activated nitrogen-containing alumino calcium silicate (CaO—Al 2 O 3 —SiO 2 )-based phosphor, a europium-activated silicate ((Sr,Ba) 2 SiO 4 )-based phosphor, a β sialon phosphor, a nitride-based phosphor such as a CASN-based or SCASN-based phosphor, a KSF-based phosphor (K 2 SiF 6 :Mn), and a sulfide-based phosphor, for example. In addition to these phosphors, any phosphor may be used that has a similar performance, function and/or effect. 
     The wavelength converting member  52  may include any of light-emitting substances so-called “nanocrystal” and “quantum dot”, for example. These materials may be semiconductor materials, e.g., II-VI group, III-V group and IV-VI group semiconductors, and specific examples thereof include nano-sized high dispersion particles such as CdSe, core-shell-type CdS x Se 1-x /ZnS and GaP. 
     Using the light-emitting module  102 , it is possible to suppress the brightness non-uniformity even with a thin structure. 
     Third Embodiment 
       FIG. 7A  is a schematic diagram showing a cross-sectional structure of a backlight  104  of the present embodiment. The backlight  104  includes a housing  60  and the light-emitting module  102 . 
     The housing  60  includes a bottom portion  60 A and a side portion  60 B. The bottom portion  60 A has a primary surface  60 m supporting the integrated light-emitting device  103  of the light-emitting module  102 , and the base material  11  of the base member  10  is in contact with the primary surface  60 m, for example. The side portion  60 B is arranged on the bottom portion  60 A so as to surround the integrated light-emitting device  103  supported on the primary surface  60   m,  and includes a first flat surface  60   a,  a second flat surface  60   b  and a lateral surface  60   c.  In the present embodiment, because the integrated light-emitting device  103  and the transparent laminate  50  each have a rectangular shape as seen from above, the side portion  60 B is arranged in four locations corresponding to the four sides of the rectangular shape. That is, the housing includes four side portions  60 B corresponding to the four sides of the rectangular shape, and each side portion  60 B includes the first flat surface  60   a,  the second flat surface  60   b  and the lateral surface  60   c.    
     The first flat surface  60   a  of the side portion  60 B supports the end portion of the transparent laminate  50 . Thus, the transparent laminate  50  is arranged on the light-extracting surface side of the light-emitting devices  101  of the integrated light-emitting device  103 , i.e., on the upper surface side of the light-emitting element  21  of the base member  10 . As described above, the transparent laminate  50  may be in contact with, or spaced apart from, the light reflective member  15 . 
     The second flat surface  60   b  is farther away from the primary surface  60   m  of the bottom portion  60 A than the first flat surface  60   a  in the z axis direction. The second flat surface  60   b  is to be in contact with the end portion of a display panel such as a liquid crystal display panel, to which the backlight  104  is attached. Thus, the backlight  104  is attached to a display panel. 
     The lateral surface  60   c  is located between the first flat surface  60   a  and the second flat surface  60   b  in the z axis direction and faces the lateral surface (end face)  50   t  of the transparent laminate  50 . When the laminate  50  has a rectangular shape as described above, the lateral surface  60   c  of the housing  60  faces each of the four lateral surfaces  50   t  of the laminate  50  and surrounds the laminate  50  along the four lateral surfaces  50   t.    
     The backlight  104  preferably includes a reflective film  62  supported on the housing  60 . Specifically, the reflective film  62  is provided as a reflective member on the lateral surface  60   c  of the housing  60 , and the reflective film  62  preferably faces the lateral surface  50   t.  The reflective film  62  preferably has a reflective characteristic to diffusely reflect the incident light. The reflective film  62  can be formed from a similar material to the material of the insulative layer  13 , for example. Specifically, a material obtained by mixing a white filler in a resin such as epoxy, silicone, modified silicone, a urethane resin, an oxetane resin, acrylic, polycarbonate or polyimide can be used as the reflective film  62 . There may be a gap between the reflective film  62  and the lateral surface  50   t  of the laminate  50 , or the reflective film  62  may be in contact with the lateral surface  50   t  with no gap therebetween. 
     In the backlight  104 , the reflective film  62  reflects light emitted from the lateral surface  50   t  of the transparent laminate  50  and have the light travel from the lateral surface  50   t  back into the transparent laminate  50 . Threrefore, the light that is not subject to wave conversion is reduced to tend to emit outide from the side the lateral surface  50   t  of the transparent member  50  or through the peripheral portion of an upper surface  50   a  of the transparent member  50  more than through the central portion of the upper surface  50   a  so that the peripheral portion of an upper surface  50   a  does notappear bluish as compared with the central portion to cause a poor emission color uniformity. As a result, it is possible to realize a backlight that is thin and has a high uniformity of emitted light. 
     The backlight  104  may include, in the transparent laminate  50 , other layers such as a prism sheet and a reflective layer, in addition to the diffuser plate  51  and the wavelength converting layer  52 . For example, another transparent layer  53  such as a prism sheet or a reflective polarizer sheet for increasing the light component that is vertically incident on the display panel may be provided. When the transparent laminate  50  includes the transparent layer  53  having such an optical characteristic, light that propagates through the transparent layer  53  and exits through the lateral surface  50   t  of the transparent laminate  50  may increase, thereby lowering the uniformity of light in the peripheral portion of the upper surface  50   a  as described above. Even in such a case, it is possible with the backlight  104  to increase the uniformity of light emitted from the backlight  104  because of the function of the reflective film  62  described above. 
     As shown in  FIG. 7B , instead of providing the reflective film  62  on the lateral surface  60   c  of the housing  60 , the backlight  104  may include a reflector plate  63  supported on the first flat surface  60   a  as a reflective member between the lateral surface  60   c  and the lateral surface  50   t  of the transparent laminate  50 . The reflector plate  63  may be made entirely of a reflective material, or may include a non-reflective substrate and a reflective film formed on the surface of the substrate. The reflector plate  63  faces the lateral surface  50   t  of the transparent laminate  50 . Also, in a case in which the backlight  104  includes the reflector plate  63 , it is possible to increase the uniformity of emitted light as described above. 
     As described above, a backlight of the present embodiment includes a light-emitting module, a transparent laminate including the wavelength converting member and the dielectric multi-layer film, a housing that supports an integrated light-emitting device of the light-emitting module and the transparent laminate with a predetermined gap therebetween, and a reflective member supported on the housing and facing the lateral surface of the transparent laminate. 
     Another backlight of the present embodiment includes a light-emitting module, a transparent laminate including the wavelength converting member and the dielectric multi-layer film, and a reflective member facing the lateral surface of the transparent laminate. 
     A light-emitting device, an integrated light-emitting device and a light-emitting module of the present disclosure can be used in various light sources such as backlights of liquid crystal displays and lighting apparatuses. 
     While exemplary embodiments of the present invention have been described above, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically described above. Accordingly, it is intended by the appended claims to cover all modifications of the invention that fall within the true spirit and scope of the invention.