JP7054018B2 - Light emitting device - Google Patents

Description

The present disclosure relates to a light emitting device.

As a backlight used in a liquid crystal display device or the like, a direct type light emitting device is known (for example, Patent Document 1 below). The direct type light emitting device generally has a structure in which a plurality of semiconductor light emitting elements are arranged two-dimensionally, and it is easy to obtain a high contrast ratio as compared with an edge type light emitting device in which light is incident from the side surface of a light guide plate. ..

Japanese Unexamined Patent Publication No. 2016-406262 Japanese Unexamined Patent Publication No. 2012-06447

In the field of display devices, in addition to improving the contrast ratio, there is a demand for reducing the thickness.

The light emitting device of the present disclosure is located at least between a substrate, a plurality of light sources located on the substrate, a light diffusing plate located above the plurality of light sources, the plurality of light sources, and the light diffusing plate. A wavelength conversion layer that absorbs at least a part of light from a plurality of light sources and emits light having a wavelength different from that of the light from the plurality of light sources, and provided on the surface of the wavelength conversion layer on the light diffusing plate side. Each comprises a plurality of scattering and reflecting portions located above at least a part of the upper surface of the plurality of light sources.

According to the embodiment of the present disclosure, a direct type light emitting device having a smaller thickness is provided.

FIG. 3 is a schematic cross-sectional view of a light emitting device according to the first embodiment of the present disclosure. It is a schematic cross-sectional view which shows the part of FIG. 1 enlarged. It is a figure which shows an example of the wiring pattern in a conductor wiring layer 12. It is a figure which shows an example of the light distribution characteristic of the light emitted from a light source 20. It is a top view schematically showing an example of the positional relationship between the scattering reflection unit 50 and the upper surface of the light source 20. It is a top view which shows the other example of a scattering reflection part. It is a top view schematically showing the details of the structure of the scattering reflection part 50'shown in FIG. 6A. It is a schematic cross-sectional view which shows the other example of the structure of the scatter reflection part 50'. FIG. 3 is a schematic cross-sectional view of a light emitting device according to a second embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view of a light emitting device according to another embodiment of the present disclosure. It is a schematic sectional view schematically showing one of the light emitting spaces 17 shown in FIG. 8 and the periphery thereof in an enlarged manner. It is a top view when the section member 15 and the light source 20 are seen along the z direction. FIG. 3 is a schematic cross-sectional view of a light emitting device according to still another embodiment of the present disclosure.

Hereinafter, embodiments of the light emitting device of the present disclosure will be described in detail with reference to the drawings. The following embodiments are examples, and the light emitting device of the present disclosure is not limited to the following embodiments. In the following description, terms indicating a specific direction or position (eg, "top", "bottom", "right", "left" and other terms including those terms) may be used. These terms are only used to clearly indicate the relative orientation or position in the referenced drawing. If the relative directions or positional relationships in terms such as "top" and "bottom" in the referenced drawings are the same, the layout is not the same as the referenced drawings in drawings other than the present disclosure, actual products, etc. You may. In addition, the size and positional relationship of the components shown in the drawings may be exaggerated for the sake of clarity, and may be the size in the actual light emitting device or the size between the components in the actual light emitting device. It may not exactly reflect the relationship. In addition, in order to avoid the drawing from becoming excessively complicated, the illustration of some elements may be omitted in a schematic cross-sectional view or the like.

(First Embodiment)
FIG. 1 schematically shows a cross section of a light emitting device according to the first embodiment of the present disclosure. For reference, in FIG. 1, arrows indicating the x-direction, y-direction, and z-direction orthogonal to each other are drawn. Other drawings of the present disclosure may also indicate these arrows. The light emitting device 100A shown in FIG. 1 includes a substrate 10, a plurality of light sources 20, a wavelength conversion layer 30A, a scattering / reflecting unit 50, and a light diffusing plate 70. The light emitting device 100A is used, for example, as a backlight for a liquid crystal display device or the like. Hereinafter, each component will be described in detail.

[Board 10]
The substrate 10 has an upper surface 10a and a lower surface 10b. The plurality of light sources 20 are located on the upper surface 10a of the substrate 10.

As the material of the substrate 10, for example, ceramics and resin can be used. Resin may be selected as the material of the substrate 10 from the viewpoint of low cost and ease of molding. Examples of the resin include phenol resin, epoxy resin, polyimide resin, bismaleimide triazine resin (BT resin), polyphthalamide (PPA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like. The substrate 10 may be a rigid substrate or a flexible substrate that can be manufactured by a roll-to-roll method. The thickness of the substrate 10 can be appropriately selected. The rigid substrate may be a bendable thin rigid substrate.

Further, ceramics may be selected as the material of the substrate 10 from the viewpoint of excellent heat resistance and light resistance. Examples of the ceramics include alumina, mulite, forsterite, glass ceramics, nitride-based (for example, AlN), carbide-based (for example, SiC), and LTCC (Low Temperature Co-fired Ceramics).

The substrate 10 may be formed of a composite material, and for example, the above-mentioned resin may be mixed with an inorganic filler such as glass fiber, SiO ₂ , TiO ₂ , or Al ₂ O ₃ . As a result, it is possible to improve the mechanical strength of the substrate 10, reduce the coefficient of thermal expansion, improve the light reflectance, and the like. For example, a glass fiber reinforced resin (glass epoxy resin) or the like may be used as the material of the substrate 10.

The substrate 10 may be a wiring board having a conductor wiring layer for supplying power to the light source 20 on its upper surface 10a. The substrate 10 may have at least the upper surface 10a having an electrical insulating property, and for example, a metal plate having an insulating layer on the surface thereof can be used as the substrate 10. The substrate 10 may have a laminated structure.

[Conductor wiring layer 12]
FIG. 2 schematically shows a part of FIG. 1 in an enlarged manner. In the configuration exemplified in FIG. 2, the light emitting device 100A has a conductor wiring layer 12 provided on the upper surface 10a of the substrate 10. The conductor wiring layer 12 has a wiring pattern for supplying electric power to each light source 20 from the outside. Here, each light source 20 is electrically connected to and fixed to the conductor wiring layer 12 by connecting the positive electrode and the negative electrode to the conductor wiring layer 12 by a joining member 26 described later.

The material of the conductor wiring layer 12 can be appropriately selected depending on the material of the substrate 10, the manufacturing method, and the like. When, for example, ceramics are used as the material of the substrate 10, a refractory metal capable of simultaneous firing with the ceramics of the substrate 10 can be used as the material of the conductor wiring layer 12. For example, the conductor wiring layer 12 can be formed of a refractory metal such as tungsten or molybdenum. When, for example, a glass epoxy resin is used as the material of the substrate 10, it is beneficial to select a material that is easy to process as the material of the conductor wiring layer 12. For example, a metal layer such as copper or nickel formed by plating, sputtering, vapor deposition, or pasting by pressing can be used as the conductor wiring layer 12. If printing, photolithography, or the like is applied as a method for forming the conductor wiring layer 12, a metal layer having a predetermined wiring pattern can be relatively easily formed.

The conductor wiring layer 12 may include a plurality of wiring patterns. Each wiring pattern may be connected to a driver driving the light source 20. For example, each wiring pattern electrically connects one of the plurality of light sources 20 to the driver. Each of the wiring patterns may connect two or more light sources 20 in series. The driver may be arranged on a substrate separate from the substrate 10 and electrically connected to the conductor wiring layer 12, or may be arranged on the substrate 10 and electrically connected to the conductor wiring layer 12. .. By connecting a driver to the conductor wiring layer 12 including a wiring pattern in which two or more light sources 20 are connected in series, a plurality of light sources 20 are connected in units of one, or in units of segments including a plurality of light sources 20. It can be driven and the light source 100A can be operated by local dimming.

FIG. 3 shows an example of a wiring pattern in the conductor wiring layer 12. In the configuration exemplified in FIG. 3, each of the conductor wiring layers 12 has a plurality of wiring patterns 12p connected to n * m light sources 20 (“*” represents multiplication). In each wiring pattern 12p, n light sources 20 are connected in series, and m groups of light sources 20 connected in series are connected in parallel. These wiring patterns 12p are connected to the driver 29 and are driven in units of region DM including n * m light sources 20. That is, under such a circuit configuration, local dimming operation in units of region DM including n * m light sources 20 is possible.

The form of wiring of the conductor wiring layer 12 is not limited to a specific form. The driving method of the light source 20 via the conductor wiring layer 12 by the driver may be a passive matrix method or an active matrix method.

The conductor wiring layer 12 may have a multi-layer structure. For example, the conductor wiring layer 12 includes a pattern of a refractory metal formed by the above-mentioned method and a layer containing other metals such as nickel, gold, and silver formed on the pattern by plating, sputtering, vapor deposition, or the like. May have.

[Metal layer 14]
As shown in FIG. 2, a metal layer 14 may be provided on the lower surface 10b of the substrate 10. The metal layer 14 is provided on the entire lower surface 10b, for example, to improve the heat dissipation of the substrate 10. The metal layer 14 may have wiring or the like, and may include, for example, a circuit pattern of a drive circuit for driving the light source 20. The components constituting the drive circuit (for example, the driver described above) may be mounted on the circuit pattern of the metal layer 14. In this case, the metal layer 14 is electrically connected to the conductor wiring layer 12 by a via conductor or the like provided in the substrate 10.

[Light source 20]
The plurality of light sources 20 are arranged and supported on the upper surface 10a side of the substrate 10. Each light source 20 includes at least a light emitting element 22 having an upper surface 22a. As the light emitting element 22, a known semiconductor light emitting element such as a semiconductor laser or a light emitting diode can be used. In this embodiment, a light emitting diode is exemplified as the light emitting element 22.

The light emitting element 22 has, for example, a translucent substrate and a semiconductor laminated structure laminated on the substrate. The semiconductor laminated structure includes an active layer, an n-type semiconductor layer and a p-type semiconductor layer sandwiching the active layer, and the n-side electrode and the p-side electrode are electrically connected to the n-type semiconductor layer and the p-type semiconductor layer, respectively. To. In the present embodiment, the n-side electrode and the p-side electrode are located on the surface opposite to the upper surface 22a. The n-side electrode and the p-side electrode are electrically connected to and fixed to the conductor wiring layer 12 provided on the upper surface 10a of the substrate 10 by the joining member 26. That is, here, the light source 20 is mounted on the substrate 10 by flip-chip bonding. The n-side electrode and the p-side electrode may be arranged on the same surface side as in this example, or may be arranged on different surfaces. The light emitting element 22 may be a bare chip or may be provided with a package having a reflector on the side surface side. Further, the light emitting element 22 may have a lens or the like for widening the range of the emission angle of the light emitted from the upper surface 22a.

As schematically shown in FIG. 2, the light source 20 may have a light reflecting layer 24 on the upper surface 22a of the light emitting element 22. When the light reflecting layer 24 that covers the entire upper surface 22a of the light emitting element 22 is provided as in the example shown in FIG. 2, the light is taken out from the side surface of the light emitting element 22. By providing the light reflecting layer 24 on the upper surface 22a of the light emitting element 22, the light in the upward direction (here, the z direction) of the light emitting element 22 is reflected by the light reflecting layer 24, and the amount of light directly above the light emitting element 22 is suppressed. Ru. As a result, a bat wing type light distribution characteristic can be realized. According to such a configuration, it is possible to omit a lens or the like for imparting a butt wing type light distribution characteristic, which is advantageous in reducing the thickness of the light source 20. The light reflecting layer 24 is, for example, a dielectric multilayer film. The light reflecting layer 24 may be a metal film.

FIG. 4 shows an example of the light distribution characteristics of the light emitted from the light source 20. The light source 20 may have a butt wing type light distribution characteristic. When the light source 20 has a bat wing type light distribution characteristic, the amount of light directly above the light source 20 can be suppressed, the light distribution of each light source can be expanded, and uneven luminance can be reduced. The bat wing type light distribution characteristic is, in a broad sense, light emission at an angle in which the absolute value of the light distribution angle (φ in FIG. 2) is larger than 0 °, where the optical axis L perpendicular to the upper surface of the light source 20 is 0 °. It is defined by the emission intensity distribution with high intensity. In particular, in a narrow sense, it is defined by the emission intensity distribution in which the emission intensity is highest in the vicinity of 45 ° to 90 °. That is, in the bat wing type light distribution characteristic, the central portion is darker than the outer peripheral portion.

As the light emitting element 22, an element that emits light having an arbitrary wavelength can be selected. For example, as an element that emits blue and green light, a nitride semiconductor (In _x Aly Ga _{1-xy N} ,
A light emitting device using 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) can be used. Further, as an element that emits red light, a light emitting element containing a semiconductor such as GaAlAs, AlInGaP, GaAsP, or GaP can be used. Further, a semiconductor light emitting device made of a material other than these can also be used. Various emission wavelengths can be selected depending on the material of the semiconductor layer in the semiconductor laminated structure and the mixed crystal ratio thereof. The composition, emission color, size, number, etc. of the light emitting element to be used may be appropriately selected according to the purpose. Here, an element that emits blue light is used as the light emitting element 22, and a light source that emits blue light is exemplified as the light source 20. However, this is just an example for convenience of explanation. Needless to say, the plurality of light sources 20 may include light sources that emit light of other colors. For example, it does not matter if three types of light sources that emit red, blue, and green light are arranged on the substrate 10. For example, if a light source that emits blue light and a light source that emits another color are arranged on the substrate 10, it is possible to improve the color rendering property of the light emitted from the light emitting device 100A.

[Joining member 26]
The joining member 26 (see FIG. 2) fixes the light emitting element 22 to the conductor wiring layer 12. Here, the joining member 26 also has a function of electrically connecting the light emitting element 22 to the conductor wiring layer 12. The joining member 26 includes Au-containing alloys, Ag-containing alloys, Pd-containing alloys, In-containing alloys, Pb-Pd-containing alloys, Au-Ga-containing alloys, Au-Sn-containing alloys, Sn-containing alloys, Sn-Cu-containing alloys, and Sn. -Cu-Ag-containing alloy, Au-Ge-containing alloy, Au-Si-containing alloy, Al-containing alloy, Cu-In-containing alloy, or a mixture of metal and flux. When the p-side electrode and the n-side electrode and the conductor wiring layer 12 are electrically connected by a wire or the like, the joining member 26 covers a region of the light emitting element 22 other than the p-side electrode and the n-side electrode. It suffices if it can be fixed to the upper surface 10a of the substrate 10, and the light emitting element 22 and the conductor wiring layer 12 do not have to be electrically connected to each other.

As the joining member 26, a liquid, paste-like or solid-like (sheet-like, block-like, powder-like, wire-like) member can be used, and an appropriate member can be used according to the composition of the light emitting element, the shape of the substrate, and the like. It may be selected as appropriate. The joining member 26 may be composed of a single member, or may be used as a joining member 26 by combining several kinds of members.

See FIG. 1 again. The plurality of light sources 20 have a two-dimensional arrangement on the upper surface 10a of the substrate 10. As shown in FIG. 1, here, a plurality of light sources 20 are arranged along the x direction. Although it does not appear on the drawing because the zx cross section is shown in FIG. 1, the light source 20 is also arranged along the y direction. That is, here, the plurality of light sources 20 are arranged two-dimensionally along two orthogonal directions, that is, the x-direction and the y-direction. The light emitting device 100A may have, for example, several thousand or more light sources 20 on the substrate 10. Of course, not limited to this example, the plurality of light sources 20 may have any arrangement.

The arrangement pitch P of the light sources 20 is the distance between the centers of the two light sources 20 adjacent to each other (may be referred to as the distance between the optical axes L), and the size thereof is, for example, 0.1 mm or more and less than 5 mm. possible. The size of the arrangement pitch P is appropriately determined according to the application of the light emitting device 100A, the size of the light emitting element 22, the configuration of the scattering reflection unit 50 described later, the distance H from the upper surface 10a of the substrate 10 to the scattering reflection unit 50, and the like. Can be changed. The arrangement pitch P may be in the range of 0.2 mm or more and less than 2 mm. Alternatively, it may be in the range of 2 mm or more and less than 4 mm. The arrangement of the light sources 20 along the x direction may be evenly spaced or unequally spaced. For example, the light sources 20 may be arranged so that the distance becomes wider from the center to the periphery. The arrangement pitch P of the light source 20 along the x direction and the arrangement pitch P of the light source 20 along the y direction may be common or different from each other.

[Wavelength conversion layer 30A]
The wavelength conversion layer 30A absorbs at least a part of the light emitted from the light source 20 and emits light having a wavelength different from the wavelength of the light emitted from the light source 20. The wavelength conversion layer 30A includes a wavelength conversion member such as a phosphor and a colorant, and absorbs a part of blue light from the light source 20 to emit yellow light. Alternatively, the wavelength conversion layer 30A may absorb a part of the blue light from the light source 20 and emit green light and red light.

As schematically shown in FIG. 1, the wavelength conversion layer 30A is located at least between a plurality of light sources 20 and a light diffusing plate 70 described later, and in the present embodiment, the wavelength conversion layer 30A is each light source 20. It covers not only the upper surface of the light source but also the entire surface including the side surface. In other words, here, a part of the wavelength conversion layer 30A is also located between the two light sources 20 adjacent to each other.

As mentioned above, the arrangement of the light sources 20 on the substrate 10 can be a narrow pitch of less than 5 mm. Since the arrangement pitch P is a narrow pitch of less than about 5 mm, sufficient brightness can be secured as a backlight on the upper surface 70a side of the light diffusing plate 70 while reducing the power applied to each light source 20. Since the power applied to each light source 20 can be reduced by reducing the arrangement pitch P, even if the wavelength conversion layer 30A covers the entire light source 20, the wavelength conversion member due to the heat generated by each light source 20 can be used. Deterioration can be suppressed. In embodiments of the present disclosure, it is not essential that the wavelength conversion member have high resistance to heat or light intensity.

The wavelength conversion layer 30A can be formed by applying a material in which a wavelength conversion member is dispersed to an epoxy resin, a silicone resin, or a resin obtained by mixing them on a substrate 10 on which a light source 20 is arranged and curing the material. .. From the viewpoint of light resistance and ease of molding, it is beneficial to select a silicone resin as a material for dispersing the wavelength conversion member. The material for forming the wavelength conversion layer 30A may further include a light diffusing member or the like. In addition to adjusting the viscosity of the material that disperses the wavelength conversion member, it is also possible to adjust the viscosity of the material for forming the wavelength conversion layer 30A by adding a light diffusing member or the like.

The wavelength conversion layer 30A includes, for example, a wavelength conversion member that converts blue light into yellow light. In this case, a part of the blue light from the light source 20 is absorbed by the wavelength conversion layer 30A, and yellow light is emitted from the wavelength conversion layer 30A. White light is obtained by mixing the blue light from the light source 20 and the yellow light from the wavelength conversion layer 30A. The wavelength conversion layer 30A may include a wavelength conversion member that converts blue light into green light and a wavelength conversion member that converts blue light into red light. In this case, white light is obtained by combining blue light, green light, and red light.

Examples of the wavelength conversion member that converts blue light into yellow light include a YAG-based phosphor. Examples of the wavelength conversion member that converts blue light into green light include β-sialon phosphors, and examples of the wavelength conversion member that converts blue light into red light include fluoride-based phosphors such as KSF-based phosphors and CASN. Nitride-based fluorescent materials can be mentioned. By including the β-sialon phosphor and the fluoride-based phosphor such as the KSF-based phosphor as the wavelength conversion member in the wavelength conversion layer 30A, the color reproduction range of the light emitting device 100A can be expanded. As the phosphor, a quantum dot phosphor may be used. When the wavelength conversion layer 30A includes a wavelength conversion member, the light emitting device 22 can emit light having a short wavelength capable of efficiently exciting the wavelength conversion member (In _x Ally Ga _{1-xy N} , It is beneficial to include 0 ≦ X, 0 ≦ Y, X + Y ≦ 1).

[Scattering reflection unit 50]
The light emitting device 100A has a plurality of scattering and reflecting units 50 on the light diffusing plate 70 side of the wavelength conversion layer 30A. Here, the plurality of scattering / reflecting units 50 are arranged on the upper surface 30a of the wavelength conversion layer 30A, and each of the plurality of scattering / reflecting units 50 is the upper surface of the light source 20 (here, the surface 24a of the light reflecting layer 24). Located above at least part of. At least a part of each scattering reflection unit 50 is located, for example, on the optical axis L of the light source 20. Here, the scattering reflection unit 50 is arranged at a plurality of locations on the wavelength conversion layer 30A corresponding to the plurality of light sources 20, and scatters and reflects the incident light.

FIG. 5 shows an example of the positional relationship between the scattering reflection unit 50 and the upper surface of the light source 20 in the top view of the light emitting device 100A. For example, the scattering reflection unit 50 is provided at a plurality of locations corresponding to each light source 20, and in this example, each scattering reflection unit 50 is located above the upper surface of each light source 20.

For example, the diffuse reflection unit 50 is located in a first region R1 located at the center of the scattering reflection unit 50 and a second region R2 including a portion located outside the first region R1 in the top view. The light emitted from the light source 20 generally has a high emission intensity on the optical axis L, and the optical axis L of each light source 20 is 0 °, and the light is relatively at an angle where the absolute value of the light distribution angle is larger than 0 °. The emission intensity is low. Therefore, by providing the scattering reflection unit 50 and scattering and reflecting the light directly above the light source 20, the distance H from the upper surface 10a of the substrate 10 to the scattering reflection unit 50 is reduced, while the upper surface of the light diffuser plate 70 is used. The uneven brightness in 70a can be suppressed. Here, the distance H is equal to the distance from the upper surface 10a of the substrate 10 to the upper surface 30a of the wavelength conversion layer 30A, and may be, for example, 1 mm or less. However, this value is merely an example. The distance H may have other values depending on the application of the light emitting device 100A, the arrangement pitch P of the light source, the configuration of the scattering reflection unit 50, and the like. For example, in the use of a display device of a tablet computer, the distance H is, for example, in the range of 0.5 mm or more and 1.2 mm or less, preferably 0.8 mm or more and 1 mm or less. In applications of laptop computer display devices, the distance H is, for example, in the range of 0.5 mm or more and 1.5 mm or less, preferably 0.8 mm or more and 1.2 mm or less. In applications of display devices such as smartphones, the distance H is, for example, in the range of 0.3 mm or more and 0.8 mm or less, preferably 0.4 mm or more and 0.6 mm or less. The ratio (H / P) of the distance H to the arrangement pitch P is, for example, in the range of 0.1 or more and 0.5 or less, and preferably in the range of 0.2 or more and 0.3 or less.

In FIG. 5, the diffuse reflection unit 50 has a circular shape centered on the optical axis of each light source 20 in the top view, but the shape of the scattering reflection unit 50 is not limited to a circle. The shape of the scattering reflection unit 50, such as an ellipse or a rectangle, can be appropriately determined so that the light can be scattered more uniformly according to the light distribution characteristics of the light source 20. Further, in this example, a plurality of scattering / reflecting units 50 are separately arranged, but some of them may be shared among the scattering / reflecting units 50 adjacent to each other. Alternatively, by arranging the plurality of scattering / reflecting units 50 in close proximity to each other, a scattering / reflecting layer including the plurality of scattering / reflecting units 50 may be formed on the entire upper surface 30a of the wavelength conversion layer 30A. When the light emission intensity on the optical axis of the light source 20 is weaker than that around the optical axis because the light source 20 has a butt-wing type light distribution characteristic, for example, the diffuse reflection unit 50 may be used. It may have a ring shape when viewed from above. The diffuse reflection unit 50 may be located above at least a part of the upper surface of each light source 20.

The diffuse reflection unit 50 may be a pattern formed of a material capable of scattering and reflecting light emitted from the light source 20 (here, blue light). The scattering reflection unit 50 is, for example, a metal pattern formed by a vapor deposition method, a printing method, photolithography, or the like. Alternatively, the diffuse reflection unit 50 may be a pattern formed of a material containing the resin and the particles of the reflective material dispersed in the resin. As the particles dispersed in the resin, particles of oxides such as titanium oxide, aluminum oxide, zirconium dioxide, and silicon dioxide can be used. The average particle size of the oxide particles is, for example, about 0.05 μm or more and 30 μm or less. If a photocurable resin containing acrylate or epoxy as a main component is used as the resin for dispersing the particles of the reflective material, the resin before curing including the reflective material is applied to the upper surface 30a of the wavelength conversion layer 30A, and then, for example, ultraviolet rays are applied. The scattered reflection unit 50 can be formed by irradiating. The resin may be photo-cured by the light emitted from the light source 20. The uncured resin in which the particles of the reflective material are dispersed can be directly applied to the upper surface 30a of the wavelength conversion layer 30A by, for example, a printing method or an inkjet method.

The particles of the reflective material that scatter the light in the scattering reflection unit 50 may be uniformly distributed, and in the region where the absolute value of the light distribution angle of the light source 20 is small, compared to the region where the absolute value of the light distribution angle is large. It may be arranged at a high density. The diffuse reflection unit 50'shown in FIG. 6A includes a first portion 50a and a second portion 50b. The first portion 50a and the second portion 50b may be arranged in the first region R1 and the second region R2 (see FIG. 5) described above, respectively. For example, the first portion 50a and the second portion 50b may be located directly above the light source 20 and around the first portion, respectively.
In top view, the first region R1 can be formed to have a size equal to or larger than that of the light source 20.

The density of the reflector particles in the first portion 50a is higher than the density of the reflector particles in the second portion 50b. Here, the particle density is represented by, for example, a number density represented by the number of particles per unit area in a plane in a top view, that is, in an xy plane. By arranging the first portion 50a, which has a relatively high particle density of the reflector, in a region with higher illuminance, such as the diffuse reflector 50', the uniformity of light on the light emitting surface of the light emitting device is more effective. Can be enhanced to.

In the scattering reflection unit 50', for example, by a printing method or an inkjet method, as shown in FIG. 6B, the minute region 50c made of the uncured resin in which the particles of the reflective material are dispersed is densely arranged in the first portion 50a, and the second portion 50a is densely arranged. It can be formed by arranging the two portions 50b at a lower density than the first portion 50a. Alternatively, as shown in FIG. 6C, a first layer 50d made of an uncured resin in which particles of the reflective material are dispersed is formed in the first portion 50a and the second portion 50b, and the first layer 50d is formed only in the first portion 50a. A second layer 50e may be formed on the layer 50d. The scatter-reflecting unit 50'with the structure shown in FIG. 6B or FIG. 6C satisfies the above-mentioned relationship in the density of the particles of the reflector in the scatter-reflecting unit 50'in the xy plane. However, when the light source 20 has a light reflection layer 24 that covers the entire upper surface 22a of the light emitting element 22, the light distribution angle becomes 0 ° when the distance H from the upper surface 10a of the substrate 10 to the scattering reflection portion 50 becomes small to some extent. Areas in the vicinity may be dark. In such a case, it is not essential that the density of the reflector particles in the first portion 50a is higher than the density of the reflector particles in the second portion 50b.

[Light diffuser 70]
See FIG. The light emitting device 100A has a light diffusing plate 70 located above the plurality of light sources 20. In this example, the light transmitting layer 60 is formed on the wavelength conversion layer 30A covering the light source 20, and the light diffusing plate 70 is arranged on the light transmitting layer 60. The translucent layer 60 is, for example, a layer of a silicone resin, a silicone-modified resin, an epoxy resin, a phenol resin, a polycarbonate resin, an acrylic resin, a trimethylpentene resin or a polynorbornene resin, or a resin containing two or more of these resins. be. A flat surface is obtained by forming the translucent layer 60 so as to cover the scattering reflection portion 50. The formation of a flat surface facilitates the placement of the light diffusing plate 70 above the plurality of light sources 20.

The light diffusing plate 70 has an upper surface 70a and a lower surface 70b, and the lower surface 70b is arranged on the translucent layer 60 with the lower surface 70b facing the light source 20. When the light emitting device 100A is used, for example, as a backlight of a liquid crystal display device, the liquid crystal panel is arranged on the upper surface 70a side of the light diffusing plate 70.

The light diffusing plate 70 diffuses and transmits incident light. The light diffusing plate 70 is made of a material having little light absorption with respect to visible light, such as a polycarbonate resin, a polystyrene resin, an acrylic resin, and a polyethylene resin. The structure for diffusing light is provided on the light diffusing plate 70 by providing irregularities on the surface of the light diffusing plate 70 or by dispersing materials having different refractive indexes in the light diffusing plate 70. As the light diffusing plate 70, a member commercially available under the name of a light diffusing sheet, a diffuser film, or the like can be used. A translucent adhesive is applied to the lower surface 70b side of the light diffusing plate 70, the layer of the translucent adhesive is directed toward the upper surface 30a of the wavelength conversion layer 30A, and the phosphor sheet is attached to the wavelength conversion layer 30A. The scattering and reflecting portion 50 can be embedded in the layer of the translucent adhesive. By curing the translucent adhesive in this state, it is possible to obtain a structure in which the translucent layer 60 and the light diffusing plate 70 are laminated on the wavelength conversion layer 30A as shown in FIG.

Along with the light diffusing plate 70, other commercially available optical members for the backlight may be used. The light emitting device 100A may further include, for example, a prism array layer, a reflective polarizing layer, and the like. The prism array layer has a shape in which a plurality of prisms extending in a predetermined direction are arranged, and light incident from various directions is directed toward a display panel (for example, a liquid crystal panel) facing the light emitting device 100A (here, a liquid crystal panel). Refract in the positive direction of z). For example, by arranging the prism array layer on the upper surface 70a side of the light diffusing plate 70, it is possible to increase the brightness when the light emitting device 100A is viewed from the front (z direction). The reflective polarizing layer is arranged at a position farther from the light diffusing plate 70 than, for example, the prism array layer, and the light in the polarization direction coincides with the transmission axis of the polarizing plate attached to the backlight side of the display panel such as a liquid crystal panel. Is selectively transmitted, and the polarized light in the direction perpendicular to the transmission axis is reflected toward the substrate 10. A part of the return light from the reflective polarizing layer is reflected again by the prism array layer, the light diffusing plate 70, or the wavelength conversion layer 30A. At this time, the polarization direction changes, and a component whose polarization direction is parallel to the transmission axis of the polarizing plate of the liquid crystal panel passes through the reflective polarizing layer and is incident on the liquid crystal panel. By providing the reflective polarizing layer in this way, the polarization directions of the light emitted from the light emitting device 100A can be aligned, and the polarized light effective for improving the brightness of the display panel can be emitted with high efficiency.

The light emitting device 100A sequentially forms a wavelength conversion layer 30A, a scattering reflection unit 50, and a light transmitting layer 60 on a substrate 10 on which a plurality of light sources 20 are arranged, and arranges a light diffusing plate 70 on the light transmitting layer 60. Can be made by. The scattering reflection unit 50 can be formed directly on the upper surface 30a of the wavelength conversion layer 30A by a printing method or the like. The prism array layer, the reflective polarizing layer, and the light diffusing plate 70 may be arranged at intervals along the z direction, and at least one interface of these layers is in contact with each other. May be good. However, from the viewpoint of reducing the thickness of the light emitting device 100A, it is advantageous that two optical members adjacent to each other are in contact with each other.

(Operation and effect of light emitting device 100A)
When the light emitting device 100A is used as a surface light source, it is required that the brightness unevenness and the color unevenness on the upper surface 70a of the light diffusing plate 70, which is the emission surface from the light emitting device 100A, are small. Further, the display device is generally required to reduce the thickness from the viewpoint of design, aesthetics, or functionality. Therefore, when the light emitting device 100A is used as a backlight, it is beneficial if the thickness (height) of the light emitting device 100A is small. However, if the distance between the light emitting element and the light diffusing plate is simply reduced in the direct type light emitting device, the light directly incident on the light diffusing plate from the light emitting element increases, and generally, the brightness on the upper surface of the light diffusing plate is increased. The unevenness increases.

As described with reference to FIG. 1 and the like, in the above-described embodiment, the plurality of light sources 20 are densely mounted on the upper surface 10a side of the substrate 10 and the wavelength conversion layer covers the entire set of the light sources 20. 30A is formed on the substrate 10. Therefore, the arrangement pitch P of the light source 20 is reduced as compared with the case where a plurality of light emitting elements individually sealed with a material containing, for example, a resin and a phosphor dispersed in the resin are arranged on the substrate 10. Can be done. For example, the arrangement pitch P of the light source 20 can be reduced to about several mm. Since the luminance unevenness on the upper surface 70a of the light diffusing plate 70 is suppressed by reducing the arrangement pitch P of the light source 20, the light emitting device is compared with the case where a plurality of individually sealed light emitting elements are arranged on the substrate 10. The thickness of the light source can be reduced. As described above, the dense arrangement of the plurality of light sources 20 makes it possible to reduce the power input to each light source 20 while ensuring sufficient brightness. Therefore, it is possible to suppress the influence of heat generation of the light source 20 on the wavelength conversion layer 30A while ensuring sufficient brightness. Further, since the wavelength conversion layer 30A covering the entire plurality of light sources 20 exerts the functions of wavelength conversion and protection of the light emitting element 22, the plurality of light emitting elements are individually sealed and wavelength conversion is performed by a support above them. It is not necessary to fix the layer, and the embodiments of the present disclosure are advantageous in reducing the thickness of the light emitting device.

A scattering reflection unit 50 is provided on the upper surface 30a of the wavelength conversion layer 30A. For example, by providing the scattering reflection unit 50 containing the resin and the particles dispersed in the resin on the upper surface 30a of the wavelength conversion layer 30A, the light from the wavelength conversion layer 30A is scattered and reflected by the particles in the scattering reflection unit 50. Can be done. Further, since the scattering reflection unit 50 can be formed directly on the upper surface 30a of the wavelength conversion layer 30A, the alignment deviation between the light source 20 on the substrate 10 and the scattering reflection unit 50 can be reduced, and the upper surface of the light source 20 can be formed. The diffuse reflector 50 can be more reliably arranged above at least a part.

The light source 20 is a point light source, and the illuminance of the surface illuminated by the light emitted from the light source 20 is inversely proportional to the square of the distance. Therefore, the illuminance of the light incident on the translucent layer 60 is higher than that of the second region R2 (see FIG. 5) in which the first region R1 in the vicinity directly above the light source 20 is located around the first region R1 in the top view. Is also expensive. This is because the distance between the light source 20 and the upper surface 30a of the wavelength conversion layer 30A in the first region R1 is larger than the distance between the light source 20 and the upper surface 30a of the wavelength conversion layer 30A in the second region R2. Because it is also short. By arranging the plurality of scattering reflection units 50 at a plurality of locations on the wavelength conversion layer 30A corresponding to the plurality of light sources 20 so that at least a part of each is located on the optical axis L of the light source 20, for example. Light directly above and near the light source 20 can be scattered and reflected. Therefore, it is possible to selectively diffuse the light having a high luminous flux density in the vicinity of the optical axis L of the light source 20 and further reduce the luminance unevenness.

The light source 20 may have a butt wing type light distribution characteristic. Since the light source 20 has a butt-wing type light distribution characteristic, the illuminance in the first region R1 can be reduced, so that uneven brightness on the upper surface 70a of the light diffusion plate 70, which is the emission surface from the light emitting device 100A, is suppressed. can do. In particular, since the light source 20 has a light distribution characteristic in which the amount of light having an elevation angle of less than 20 ° with respect to the horizontal direction is 30% or more of the total amount of light, uneven brightness can be further suppressed. When the light source 20 has a butt-wing type light distribution characteristic, the reflectance in the second portion 50b located in the second region R2 of the scattered reflector is set in the first portion 50a located in the first region R1. It may be higher than the reflectance.

According to the embodiment of the present disclosure, since the scattering reflection portion 50 is formed on the wavelength conversion layer 30A, the distance H from the upper surface 10a of the substrate 10 to the scattering reflection portion 50 is set to about 1 mm while suppressing the luminance unevenness. Can be reduced to. That is, according to the embodiment of the present disclosure, a direct type light emitting device having a reduced thickness is provided. The embodiments of the present disclosure can be particularly advantageously applied to the backlight of a display device of a mobile device having a strict demand for reduction in thickness, such as a display device used in a tablet computer, a smartphone, a smart watch, or the like.

In the configuration illustrated in FIG. 1, the wavelength conversion layer 30A includes a portion that covers the side surface of each light source 20. According to such a configuration, not only the light emitted from the upper surface of the light emitting element 22 but also the light emitted from the side surface can be effectively used.

A conductor wiring layer 12 may be formed on the substrate 10, each of which includes a plurality of wiring patterns connecting two or more light sources 20 in series. By connecting a driver to the wiring pattern, a plurality of light sources 20 can be driven in units of one or a plurality of segments, and the light emitting device 100A can be operated by local dimming.

(Second embodiment)
FIG. 7 schematically shows a cross section of a light emitting device according to the second embodiment of the present disclosure. The light emitting device 100B shown in FIG. 7 has a protective layer 40 covering the side surfaces of a plurality of light sources 20 and wavelength conversion on the protective layer 40, instead of the wavelength conversion layer 30A of the light emitting device 100A described with reference to FIG. It has a layer 30B. Hereinafter, the details of the protective layer 40 and the wavelength conversion layer 30B will be described.

[Protective layer 40]
The protective layer 40 is a layer that covers at least the side surface of the light source 20, and is a transparent resin layer here. Here, the upper surface 40a of the protective layer 40 is aligned with the upper surface 20a of the light source 20 (for example, the upper surface 22a of the light emitting element 22 or the surface 24a of the light reflecting layer 24). The protective layer 40 can be formed by applying an epoxy resin, a silicone resin, or a resin in which these are mixed to the substrate 10 on which the light source 20 is arranged and curing the resin. After the translucent resin material is cured, the resin layer obtained by curing the resin material is ground from the side opposite to the substrate 10 to form a protective layer 40 on the upper surface 40a where the upper surface 20a of the light source 20 is exposed. can do.

[Wavelength conversion layer 30B]
In the configuration exemplified in FIG. 7, the wavelength conversion layer 30B has a sheet shape (or layer shape) and is located on the protective layer 40. As shown in FIG. 7, the wavelength conversion layer 30B is arranged on the protective layer 40 so that the lower surface 30b thereof is in contact with the upper surface 20a of the light source 20.

As described above, according to the embodiments of the present disclosure, the light sources 20 can be arranged at a narrow pitch, and therefore sufficient brightness can be ensured while reducing the power applied to each light source 20. By reducing the electric power applied to the light source 20, the heat generated from the light source 20 can be reduced, and the deterioration of the wavelength conversion member due to the heat can be suppressed. Therefore, as shown in FIG. 7, it is possible to adopt a configuration in which the wavelength conversion layer 30B is in contact with the upper surface 20a of the light source 20.

Similar to the wavelength conversion layer 30A described above, the wavelength conversion layer 30B absorbs at least a part of the light emitted from the light source 20 and emits light having a wavelength different from the wavelength of the light emitted from the light source 20. The wavelength conversion layer 30B can be formed by using the material for forming the wavelength conversion layer 30A described above. For example, as a material for forming the wavelength conversion layer 30B, a resin material in which a wavelength conversion member such as a phosphor is dispersed can be used. The wavelength conversion layer 30B can be formed directly on the protective layer 40, for example, by applying a material for forming the wavelength conversion layer 30B to the upper surface 40a of the protective layer 40 and the upper surface 20a of the light source 20. .. Alternatively, separately from the substrate 10 on which the protective layer 40 is formed, a phosphor sheet in which the resin in the resin material in which the wavelength conversion member such as a phosphor is dispersed is in the B stage state is prepared, and the sheet is protected. It is also possible to form the wavelength conversion layer 30B by arranging it on the layer 40. When a sheet containing a wavelength conversion member (for example, a fluorescent material sheet) is prepared separately from the substrate 10, ceramics containing, for example, glass, alumina, etc. should be used instead of the resin as a material for dispersing the wavelength conversion member. Is also possible.

Also in the second embodiment, the scattering reflection unit 50 is arranged on the upper surface 30a of the wavelength conversion layer (here, the wavelength conversion layer 30B). By providing the diffuse reflection unit 50 on the wavelength conversion layer 30B, the effect of reducing the luminance unevenness can be obtained as in the first embodiment. The structure exemplified in FIG. 7 has, for example, a pattern formed from a material containing a resin and particles of a reflective material dispersed in the resin on one surface of a sheet including a wavelength conversion member, and / or a metal pattern. It is obtained by arranging a sheet formed by a printing method and having a pattern formed on the protective layer 40. However, when the sheet on which the pattern is formed is arranged on the protective layer 40, the substrate 10 is compared with the first embodiment in which the scattering reflection unit 50 can be directly formed on the wavelength conversion layer 30A covering the light source 20. There is a possibility that an alignment shift will occur between the above light source 20 and the scattering reflection unit 50 on the wavelength conversion layer 30B. However, in the second embodiment, as described in Patent Document 2, a sheet-like phosphor layer having a pattern of a reflective layer on one main surface is arranged away from the upper surface of the LED chip. However, the wavelength conversion layer 30B can be arranged close to the upper surface 20a of the light source 20. Therefore, it can be said that it is more advantageous than the conventional configuration in terms of reducing the alignment deviation. The wavelength conversion layer 30B is formed on the protective layer 40 by applying the material for forming the wavelength conversion layer 30B to the upper surface 40a of the protective layer 40 and the upper surface 20a of the light source 20, and then on the wavelength conversion layer 30B. If the scattering reflection unit 50 is formed on the surface, it is possible to suppress the occurrence of alignment misalignment as in the first embodiment.

(Modification example)
FIG. 8 schematically shows a cross section of a light emitting device according to another embodiment of the present disclosure. The light emitting device 100C shown in FIG. 8 further has a dividing member 15 located between the substrate 10 and the wavelength conversion layer 30B as compared with the light emitting device 100B described with reference to FIG. 7. Hereinafter, the details of the division member 15 will be described.

[Division member 15]
The dividing member 15 has a bottom portion 15b and a wall portion 15ay extending in the y direction. As shown in FIG. 8, the wall portion 15ay is located between two light sources 20 adjacent to each other in the x direction. Further, although not shown in FIG. 8, the dividing member 15 has a wall portion extending in the x direction (wall portion 15ax, see FIG. 10 described later) between two light sources 20 adjacent to each other in the y direction. A light emitting space 17 having an opening 17h is formed by a bottom portion 15b, two wall portions 15ay facing each other in the x direction, and two wall portions 15ax facing each other in the y direction (not shown in FIG. 8). In the configuration illustrated in FIG. 8, each light source 20 is located in the light emitting space 17. Above the light source 20, a wavelength conversion layer 30B is arranged so as to cover the opening 17h of the light emitting space 17.

FIG. 9 schematically shows one of the light emitting spaces 17 shown in FIG. 8 and its surroundings in an enlarged manner. The wall portion 15ay extending in the y direction includes a pair of inclined surfaces 15t extending in the y direction. As shown in FIG. 9, the pair of inclined surfaces 15t face the opening 17h of the light emitting space 17 in the zx cross section. The wall portion 15ay has a top portion 15c, and in this example, the top portion 15c of the wall portion 15ay is in contact with the lower surface 30b of the wavelength conversion layer 30B. Similarly, the wall portion 15ax extending in the x direction (not shown in FIG. 8) also includes a pair of inclined surfaces 15s extending in the x direction, and the pair of inclined surfaces 15s also have an opening of the light emitting space 17 in the yz cross section (not shown). Facing 17h. The wall portion 15ax (not shown) also has a top portion 15c like the wall portion 15ay, and in this example, the top portion 15c of the wall portion 15ax is also in contact with the lower surface 30b of the wavelength conversion layer 30B. It is not essential that the top 15c of the wall 15ay or the top 15c of the wall 15ax is in contact with the wavelength conversion layer. However, when the wall portion 15ay and the top portion 15c of the wall portion 15ax are in contact with the wavelength conversion layer, it is possible to suppress the incident of the light emitted from the light source 20 in one light emitting space 17 into the adjacent light emitting space 17.

The classification member 15 is formed of, for example, a resin containing a reflective material and has light reflectivity. The dividing member 15 reflects the light emitted from the light source 20 toward the opening 17h of the light emitting space 17 on the inclined surface 15s of the wall portion 15ax and the inclined surface 15t of the wall portion 15ay. Further, the light incident on the bottom portion 15b is also reflected to the opening 17h side of the light emitting space 17. By providing the dividing member 15 surrounding each of the plurality of light sources 20 on the substrate 10, the light emitted from the light source 20 can be efficiently incident on the wavelength conversion layer (here, the wavelength conversion layer 30B), and the light is diffused. The brightness on the upper surface 70a of the plate 70 (see, for example, FIG. 8) can be improved.

As shown in FIG. 9, a through hole 15e is provided in the center of the bottom portion 15b, and the light source 20 is located in the through hole 15e. The shape and size of the through hole 15e are not particularly limited, and may be any shape and size as long as the light source 20 can be located inside. From the viewpoint of utilizing the reflection at the bottom portion 15b of the dividing member 15, it is advantageous that the outer edge of the through hole 15e is located in the vicinity of the light source 20. That is, it is advantageous that the gap generated between the through hole 15e and the light source 20 is narrow in the top view because the light utilization efficiency can be improved.

As described above, the partitioning member 15 has light reflectivity. For example, the classification member 15 may be formed by using a resin containing a reflective material composed of oxide particles such as titanium oxide, aluminum oxide, and silicon oxide, or after molding using a resin not containing a reflective material, the partitioning member 15 may be formed. A reflective material may be provided on the surface. The reflectance of the dividing member 15 with respect to the light emitted from the light source 20 is, for example, 70% or more.

The dividing member 15 can be formed by molding using a mold or by stereolithography. As a molding method using a mold, a molding method such as injection molding, extrusion molding, compression molding, vacuum molding, pressure molding, press molding or the like can be applied. For example, by applying vacuum forming to a reflective sheet formed of PET or the like, a shape in which the bottom portion 15b and the wall portions 15ax and 15ay are integrally formed can be obtained. The thickness of the reflective sheet is, for example, 100 to 500 μm.

In this example, the insulating member 16 is provided on the conductor wiring layer 12, and the lower surface of the bottom portion 15b of the dividing member 15 is fixed to the upper surface 16a of the insulating member 16 described later. The portion surrounded by the insulating member 16 and the two inclined surfaces 15t of the wall portion 15ay (or the two inclined surfaces 15s of the wall portion 15ax) may be hollow or may be filled with resin or the like. You may. For example, a portion surrounded by the insulating member 16 and the two inclined surfaces 15t of the wall portion 15ay may be filled with a material for forming the dividing member 15.

FIG. 10 is a top view of the dividing member 15 and the light source 20 when viewed along the z direction. In FIG. 10, nine light emitting spaces 17 arranged in 3 rows and 3 columns are shown. As shown in the figure, each light source 20 is surrounded by two wall portions 15ax extending in the x direction and two wall portions 15ay extending in the y direction. In this example, the arrangement pitch Px in the x direction and the arrangement pitch Py in the y direction of the light source 20 are equal to each other. Therefore, here, the outer shape of the bottom portion 15b is a square.

As described above, the wall portion 15ax includes a pair of inclined surfaces 15s extending in the x direction, and the wall portion 15ay includes a pair of inclined surfaces 15t extending in the y direction. Each of the pair of inclined surfaces 15s is connected to each other on one of the two sides extending in the x direction, forming a top portion 15c. The other of the two sides extending in the x direction is connected to the bottom 15b. Similarly, each of the pair of inclined surfaces 15t is connected to each other on one of the two sides extending in the y direction, forming a top portion 15c. The other of the two sides extending in the y direction is connected to the bottom 15b. The bottom portion 15b is located in a region 15r surrounded by two wall portions 15ax and two wall portions 15ay.

The light emitting space 17 partitioned by the dividing member 15 is the minimum unit of the light emitting region when a plurality of light sources 20 are independently driven. Therefore, when a plurality of light sources 20 are independently driven, the light emitting space 17 becomes the minimum unit of local dimming when the light emitting device 100C is viewed from the upper surface 70a side of the light diffusing plate 70 as a surface light emitting device, and a plurality of light sources 20 are driven independently. If the light source 20 is driven independently, a light emitting device capable of local dimming drive in the smallest unit is realized. If a plurality of adjacent light sources 20 are simultaneously driven and driven so as to synchronize the ON / OFF timings, it is possible to drive by local dimming in a larger unit.

[Insulation member 16]
As described above, in this example, the insulating member 16 is interposed between the dividing member 15 and the conductor wiring layer 12. The insulating member 16 is provided with a through hole 16e, and as shown in FIG. 10, the light source 20 in each region 15r is located in the through hole 16e.

See FIG. 9 again. The insulating member 16 covers a region of the conductor wiring layer 12 other than the region electrically connected to the light source 20 and other elements. The insulating member 16 functions as a resist that imparts insulating properties to a region of the conductor wiring layer 12 in which the light source 20 and other elements are not arranged.

The insulating member 16 can be formed by using a resin material such as an epoxy resin, a urethane resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an oxetane resin, a silicone resin, or a modified silicone resin. The insulating member 16 may be formed from a material in which a reflective material composed of oxide particles such as titanium oxide, aluminum oxide, and silicon oxide is dispersed in a resin material. By using such a material and providing an insulating member 16 having light reflectivity on the conductor wiring layer 12, the light from the light source 20 is reflected on the upper surface 10a side of the substrate 10, and the light on the substrate 10 side is reflected. It is possible to prevent leakage and absorption and improve the light extraction efficiency of the light emitting device 100C. The reflectance of the insulating member 16 with respect to the light emitted from the light source 20 is, for example, 70% or more.

From the viewpoint of increasing the light utilization efficiency by reflecting the light incident on the light-reflecting insulating member 16 toward the upper side of the light source 20, it occurs between the outer edge of the through hole 16e and the light source 20 in the top view. It is advantageous that the gap is narrow. However, if the gap generated between the outer edge of the through hole 16e and the light source 20 is made small, the proportion of light reflected directly above the light source 20 increases, and uneven brightness is likely to occur. In the embodiment of the present disclosure, a scattering reflection unit 50 located above at least a part of the upper surface of the light source 20 is provided on the wavelength conversion layer (here, the wavelength conversion layer 30B). Therefore, the light directly above and in the vicinity of the light source 20 can be scattered and reflected by the scattering reflection unit 50, and even when the gap generated between the through hole 16e and the light source 20 is reduced, the light directly above the light source 20 It is possible to reduce the brightness and suppress the uneven brightness.

The dividing member 15 is fixed to the upper surface 16a of the insulating member 16 by, for example, an adhesive member. The adhesive member may be a double-sided tape, a hot-melt type adhesive sheet, or a thermosetting resin or a thermoplastic resin adhesive liquid. It is beneficial if the adhesive member has high flame retardancy. By arranging the adhesive member around the through hole 15e, it is possible to suppress the incident light emitted from the light source 20 between the insulating member 16 and the dividing member 15. For example, the adhesive member may be arranged in a ring shape along the outer edge of the through hole 15e. The fixing of the dividing member 15 is not limited to the fixing by the adhesive member, and the dividing member 15 may be fixed to the insulating member 16 by other connecting members such as screws and pins.

In this example, the light emitting space 17 defined by the wall portions 15ay and 15ax is filled with the material of the protective layer 40. The partitioning member 15 is fixed to the upper surface 16a of the insulating member 16, the material of the protective layer 40 is applied from the partitioning member 15 side to cure the material of the protective layer 40, and then the cured material is applied to the wall portions 15ay and 15ax. By grinding to the position of the top 15c, the protective layer 40 covering the side surface of the light source 20 can be formed. After that, the wavelength conversion layer 30B and the scattering reflection unit 50 are sequentially formed on the protective layer 40, or the scattering reflection unit 50 is provided on one of the main surfaces to protect the sheet in which the wavelength conversion member is dispersed. By arranging it on the layer 40, the structure as shown in FIG. 9 can be obtained.

Alternatively, the light emitting space 17 may be filled with a material in which a wavelength conversion member is dispersed in a resin. The light emitting device 100D shown in FIG. 11 is common to the light emitting device 100A described with reference to FIG. 1 in that the wavelength conversion layer 30D in which the scattering reflection unit 50 is arranged on the upper surface 30a covers the plurality of light sources 20. However, the light emitting device 100D has a division member 15, and the wavelength conversion layer 30D covers the division member 15. Even with such a configuration, the brightness on the upper surface 70a of the light diffusing plate 70 can be improved. The distance from the upper surface 10a of the substrate 10 to the top 15c (height of the top 15c) may be appropriately adjusted according to the distance H or the like from the upper surface 10a of the substrate 10 to the scattering reflection portion 50. The top 15c may be exposed from the wavelength conversion layer 30D.

The light emitting device according to the embodiment of the present disclosure can be used as a surface light emitting device capable of local dimming control, for example, a backlight of a liquid crystal display device, a light source for various lightings, and the like.
It can be suitably used for an in-vehicle light source or the like. Since the light emitting device according to the embodiment of the present disclosure can suppress the luminance unevenness while reducing the thickness, it can be particularly advantageously applied to a backlight for a display device of a mobile device where the demand for thickness reduction is strict. ..

10 Substrate 12 Conductor wiring layer 12p Wiring pattern 14 Metal layer 15 Division member 15ax, 15ay Wall part 15b Bottom 15c Top 15e Through hole 16 Insulation member 17 Light emitting space 20 Light source 22 Light emitting element 24 Light reflecting layer 26 Joining member 30A, 30B Layer 30a Upper surface 30b Lower surface 40 Protective layer 50, 50'Scattering reflector 60 Translucent layer 70 Light diffuser 100A-100D Light emitting device

Claims (10)

With the board
A plurality of light sources located on the substrate, each of which has an upper surface provided with a light reflecting layer and two or more side surfaces , and is configured to be capable of emitting light from the two or more side surfaces. , With multiple light sources,
A light diffusing plate located above the plurality of light sources,
A wavelength conversion layer that is located at least between the plurality of light sources and the light diffusing plate, absorbs at least a part of the light from the plurality of light sources, and emits light having a wavelength different from the light from the plurality of light sources. , A wavelength conversion layer that integrally covers the plurality of light sources over the entire light diffuser .
A plurality of scattering and reflecting portions provided on the surface of the wavelength conversion layer on the light diffusing plate side, each of which is located above at least a part of the upper surface of the plurality of light sources.
Each diffuse reflector has a circle centered on the optical axis of the corresponding light source in top view.
Each of the scattering and reflecting portions is located in a first region located in the center of each scattering and reflecting portion and a second region including a portion located outside the first region in a top view.
A light emitting device in which each of the scattering and reflecting portions contains particles of the reflective material, and the density of the particles of the reflective material in the first region is higher than the density of the particles of the reflective material in the second region . The light emitting device according to claim 1, wherein the wavelength conversion layer has a portion that covers the side surface of each light source. Further with a protective layer covering at least the sides of each light source,
The light emitting device according to claim 1, wherein the wavelength conversion layer is located on the protective layer. The light emitting device according to any one of claims 1 to 3, further comprising a conductor wiring layer including a plurality of wiring patterns, each of which is connected to one or more light sources. The light emitting device according to any one of claims 1 to 4, wherein the plurality of light sources have an arrangement pitch of 0.1 mm or more and less than 5 mm. The distance from the surface of the substrate on which the plurality of light sources are located to the plurality of scattering and reflecting portions is 1.
.. The light emitting device according to any one of claims 1 to 5, which is 5 mm or less. The light emission according to any one of claims 1 to 6, wherein the ratio of the distance from the surface of the substrate to the plurality of scattering and reflecting portions to the arrangement pitch of the light source is 0.1 or more and 0.5 or less. Device. The light emitting device according to any one of claims 1 to 7, wherein the plurality of scattering and reflecting portions further contain a resin, and the particles of the reflecting material are dispersed in the resin. The light emitting device according to any one of claims 1 to 8, further comprising a partitioning member having a plurality of regions formed by a wall portion having a top and surrounding each of the plurality of light sources on the substrate. The light emitting device according to any one of claims 1 to 9 , wherein the wavelength conversion layer has a portion covering two or more side surfaces of each of the light sources.

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