JP7029077B2 - Luminescent device - Google Patents

Description

The present disclosure relates to a light emitting device.

A surface light emitting device is known as a direct type backlight used in liquid crystal televisions and the like. For example, as an example of the surface light emitting device, in the light emitting device described in Cited Document 1, a plurality of light sources are arranged in a matrix, and a convex portion protruding in a curved shape is integrally formed above the plurality of light sources. It has a diffuser plate. This makes it possible to suppress the occurrence of uneven luminance when viewed from the display surface side of the surface light emitting device.

Japanese Unexamined Patent Publication No. 2012-221779

However, when the light source is locally dimmed by such a light emitting device, the light emitted from the light source in the lighting area and scattered and guided by the diffuser plate or the like is incident on the non-lighting area adjacent to the lighting area and is not lit. The contrast ratio between the area and the lighting area may decrease. Further, when viewed from the display surface side of the surface light emitting device, it is still not possible to sufficiently eliminate the uneven brightness, and there is a demand for measures to obtain more uniform surface light emission.
The present disclosure has been made in view of the above problems, and is a light emitting device capable of effectively suppressing luminance unevenness and further improving the contrast ratio between a lit area and a non-lit area. I will provide a.

The present application includes the following inventions.
A board with multiple light sources and
A division member that surrounds each of the light sources and has a wall portion having a top portion and an inclined surface, the area surrounded by the wall portion is defined as one division, and a plurality of the divisions are provided.
A light emitting device having a diffuser plate having a first convex portion surrounding the light source in a region arranged above the light source and facing the substrate and overlapping the inclined surface in a plan view.

According to the light emitting device according to the embodiment of the present invention, the uneven brightness can be effectively suppressed, and the contrast ratio between the lit area and the non-lit area can be further improved.

It is a schematic sectional drawing of the light emitting device of one Embodiment of this invention. It is a schematic plan view of the light emitting device of FIG. 1A. It is a partially enlarged schematic cross-sectional view around the light emitting element of the light emitting device of FIG. 1A. FIG. 3 is a schematic plan view for explaining the positional relationship between the diffuser plate and the division member in one division of the light emitting device of FIG. 1A. FIG. 1A is a partially enlarged schematic cross-sectional view of the vicinity of the division member of the light emitting device of FIG. 1A. It is a schematic sectional drawing of the light emitting device of another embodiment of this invention. It is a schematic sectional drawing of the light emitting device of still another embodiment of this invention. 2A and 2C are schematic plan views for explaining the positional relationship between the diffusion plate and the division member in one division of the 2C light emitting device. FIG. 2 is a partially enlarged schematic cross-sectional view of a diffuser plate in the light emitting device of FIG. 2A. It is a schematic sectional drawing of the light emitting device of still another embodiment of this invention. It is a schematic sectional drawing of the light emitting device of still another embodiment of this invention. FIG. 3 is a partially enlarged schematic cross-sectional view of the vicinity of another section member of the light emitting device of FIG. 1A.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as appropriate. However, the embodiments described below are for embodying the technical idea of the present disclosure, and the present disclosure is not limited to the following unless otherwise specified. Further, the contents described in one embodiment and the embodiment can be applied to other embodiments and the embodiments. The size and positional relationship of the members shown in each drawing may be exaggerated for the sake of clarity.
In the present embodiment, the light extraction surface of the light source may be referred to as the upper surface, and the light extraction surface side may be referred to as the upper surface.

As shown in FIGS. 1A and 1B, the light emitting device according to the embodiment of the present invention includes a plurality of light sources 11, a substrate 12, a dividing member 13, and a diffusion plate 14. The plurality of light sources 11 are arranged on the substrate 12. The dividing member 13 surrounds each of the light sources 11 and has a wall portion 13A having a top portion 13a and an inclined surface 13b. The range surrounded by the wall portion 13A including the top portion 13a (that is, the area and the space) is defined as one division C, and the division member 13 includes a plurality of divisions C. The diffusion plate 14 is arranged above the light source 11 and has a first convex portion 14a surrounding the light source 11 in a region M on a surface facing the substrate 12 and overlapping the inclined surface 13b in a plan view. This light emitting device functions as a surface light emitting device.
In this way, in the region of the diffuser plate 14 where the light emitted from the light source 11 and irradiated and reflected on the inclined surface 13b of the dividing member 13 is concentrated, that is, in the region M overlapping the inclined surface in a plan view, the first convex portion. By arranging the light sources, the concentrated light can be effectively dispersed. As a result, when the light emitting device is viewed from the light extraction surface side, uneven brightness can be effectively suppressed. Further, by arranging the dividing member 13 at an appropriate position, it is possible to prevent the light emitted from the specific light source 11 from entering the adjacent region. Thereby, it is possible to effectively prevent or reduce the invasion of light into the adjacent region. As a result, the contrast ratio can be further improved when the adjacent area is a non-lighting area.

(Light source 11)
The light source 11 is a member that emits light, for example, a light emitting element itself that emits light by itself, a light emitting element sealed with a translucent resin or the like, or a surface-mounted light emitting device (LED) in which the light emitting element is packaged. Also called) etc.
For example, as the light source 11, as shown in FIG. 1C, a light emitting element 15 coated with a sealing member 21 can be mentioned. The light source may be one using one light emitting element 15, but may be one using a plurality of light emitting elements as one light source.
The light source 11 may have any light distribution characteristic, but has a wide light distribution in order to illuminate with less luminance unevenness in each division C surrounded by the wall portion 13A of the division member 13 described later. Is preferable. In particular, it is preferable that each of the light sources 11 has a butt wing light distribution characteristic. As a result, the amount of light emitted in the direction directly above the light source 11 is suppressed, the light distribution of each light source is expanded, and the expanded light is applied to the wall portion 13A and the bottom surface 13c, thereby being surrounded by the wall portion 13A. Brightness unevenness in each category C can be suppressed.
Here, the bat wing light distribution characteristic is defined as having a light emission intensity distribution in which the light emission intensity is stronger than 0 ° at an angle where the absolute value of the light distribution angle is larger than 0 °, where the optical axis L is 0 °. .. As shown in FIG. 1C, the optical axis L is defined by a line that passes through the center of the light source 11 and intersects a line on the plane of the substrate 12, which will be described later, perpendicularly.
In particular, as the light source 11 having the butt wing light distribution characteristic, for example, as shown in FIG. 1C, a light source 15 using a light emitting element 15 having a light reflecting film 20 on the upper surface can be mentioned. As a result, the upward light of the light emitting element 15 is reflected by the light reflecting film 20, the amount of light directly above the light emitting element 15 is suppressed, and the butt wing light distribution characteristic can be obtained. Since the light reflecting film 20 can be formed directly on the light emitting element 15, it is not necessary to separately combine a special lens for bat wing light distribution, and the thickness of the light source 11 can be reduced.

The light reflecting film 20 formed on the upper surface of the light emitting element 15 may be a metal film such as silver or copper, a dielectric multilayer film (DBR film), a combination thereof, or the like. The light reflecting film 20 preferably has a reflectance angle dependence on the incident angle with respect to the emission wavelength of the light emitting element 15. Specifically, it is preferable to set the reflectance of the light reflecting film 20 so that the oblique incident is lower than the vertical incident. As a result, the change in brightness directly above the light emitting element becomes gradual, and it is possible to suppress extremely darkening such as a dark spot directly above the light emitting element.
Examples of the light source 11 include those having a height of the light emitting element 15 directly mounted on the substrate of 100 μm to 500 μm. The thickness of the light reflecting film 20 may be 0.1 μm to 3.0 μm. The thickness of the light source 11 can be about 0.5 mm to 2.0 mm even if the sealing member 21 described later is included.
It is preferable that the plurality of light sources 11 are mounted on a substrate 12 described later so that they can be driven independently of each other and dimming control (for example, local dimming or HDR) for each light source is possible.

(Light emitting element 15)
As the light emitting element 15, a known one can be used. For example, it is preferable to use a light emitting diode as the light emitting element. The light emitting element can be selected from any wavelength. For example, as the blue and green light emitting elements, those using a nitride semiconductor can be used. Further, as the red light emitting element, GaAlAs, AlInGaP and the like can be used. Further, a semiconductor light emitting device made of a material other than this may be used. The composition, emission color, size, number, etc. of the light emitting element to be used can be appropriately selected according to the purpose.
As shown in FIG. 1C, the light emitting element 15 may be flip-chip mounted via a joining member 19 so as to straddle a pair of positive and negative conductor wirings 18A and 18B provided on the upper surface of the substrate 12. However, the light emitting element 15 may be face-up mounted as well as flip-chip mounted. The joining member 19 is a member for fixing the light emitting element 15 to the substrate or the conductor wiring, and examples thereof include an insulating resin or a conductive member. When the light emitting element 15 is flip-chip mounted on a substrate, a conductive member is used. Specifically, 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, Sn- Examples thereof include Cu—Ag-containing alloys, Au—Ge-containing alloys, Au—Si-containing alloys, Al-containing alloys, Cu—In-containing alloys, and mixtures of metals and fluxes.

(Sealing member 21)
The sealing member 21 covers the light emitting element for the purpose of protecting the light emitting element from the external environment and optically controlling the light output from the light emitting element. The sealing member 21 is made of a translucent material. As the material, a translucent resin such as an epoxy resin, a silicone resin, or a resin mixed thereof, glass, or the like can be used. Of these, it is preferable to use a silicone resin in consideration of light resistance and ease of molding. The sealing member 21 includes a wavelength conversion material such as a phosphor that absorbs light from the light emitting element and emits light having a wavelength different from that of the output light from the light emitting element, and a diffuser for diffusing the light from the light emitting element. , A colorant or the like corresponding to the emission color of the light emitting element may be contained.
As the phosphor, diffuser, colorant and the like, those known in the art can be used.
The sealing member 21 may be in direct contact with the substrate 12.
The sealing member 21 is adjusted to a viscosity capable of printing, applying a dispenser, and the like, and can be cured by heat treatment and light irradiation. The shape of the sealing member 21 is, for example, a substantially hemispherical shape, a vertically long convex shape in a cross-sectional view (a shape in which the length in the Z direction is longer than the length in the X direction in the cross-sectional view), and a flat convex shape in the cross-sectional view. (A shape in which the length in the X direction is longer than the length in the Z direction in the cross-sectional view), and may be formed so as to have a circular shape or an elliptical shape in the top view.
The sealing member 21 may be arranged as an underfill 21a between the lower surface of the light emitting element 15 and the upper surface of the substrate 12.

(Board 12)
The substrate 12 is a member for mounting a plurality of light sources 11, and as shown in FIG. 1C, conductor wirings 18A and 18B for supplying electric power to the light sources 11 such as the light emitting element 15 are provided on the upper surface thereof. Have. Of the conductor wirings 18A and 18B, it is preferable that the covering member 28 is coated on the region where the electrical connection is not performed.
The material of the substrate 12 may be any material that can insulate and separate at least a pair of conductor wirings 18A and 18B. For example, ceramics, resins, composite materials and the like can be mentioned. Examples of the ceramics include alumina, mullite, forsterite, glass ceramics, nitride-based (for example, AlN), carbide-based (for example, SiC), and LTCC. Examples of the resin include phenol resin, epoxy resin, polyimide resin, BT resin, polyphthalamide (PPA), polyethylene terephthalate (PET) and the like. As the composite material, the above-mentioned resin is mixed with an inorganic filler such as glass fiber, SiO ₂ , TiO ₂ , Al ₂ O ₃ , a glass fiber reinforced resin (glass epoxy resin), and an insulating layer is formed on a metal member. Examples include metal substrates.
The thickness of the substrate 12 can be appropriately selected, and may be either a flexible substrate or a rigid substrate that can be manufactured by a roll-to-roll method. The rigid substrate may be a bendable thin rigid substrate.
The conductor wirings 18A and 18B may be made of any material as long as they are conductive members, and those usually used as a wiring layer such as a circuit board can be used. A plating film, a light reflection film, or the like may be formed on the surface of the conductor wiring.
The covering member 28 is preferably made of an insulating material. Examples of the material include the same materials as those exemplified as the substrate material. By using the above-mentioned resin containing a white filler or the like as the covering member, it is possible to prevent light leakage or absorption and improve the light extraction efficiency of the light emitting device.

(Division member 13)
As shown in FIGS. 1A, 1B, 1D, and the like, the dividing member 13 has a wall portion 13A that surrounds each of the light sources 11 and has a top portion 13a and an inclined surface 13b. The division member 13 is a member having a plurality of divisions C, with the range (region and space) surrounded by the wall portion 13A including the top portion 13a as one division C. In the plan view, the top portion 13a can be regarded as the boundary of the adjacent division C.
The division member 13 preferably has a bottom surface 13c in the division C. In other words, the division member 13 constitutes the division C by the bottom surface 13c and the wall portion 13A. In the bottom surface 13c, a through hole 13d is arranged substantially in the center in the division C. As shown in FIG. 1A and the like, it is preferable that the light source 11 is arranged in the through hole 13d. The shape and size of the through hole 13d may be any shape and size in which the entire light source 11 is exposed, and it is preferable to set the outer edge of the through hole 13d so as to be located only in the vicinity of the light source 11. As a result, when the dividing member 13 has reflectivity, the light from the light source can be reflected even on the bottom surface 13c, and the light extraction efficiency can be improved.

The top 13a is the highest portion of the wall 13A and is preferably composed of at least two wall 13A surrounding adjacent regions. The top portion 13a may be flat, but is preferably in the shape of a ridge composed of at least two wall portions 13A surrounding adjacent regions. That is, as shown in FIG. 1A and the like, it is preferable that the vertical cross section of at least two wall portions 13A constituting the top portion 13a constitutes an acute-angled triangle, and more preferably an acute-angled isosceles triangle. The acute angle of the acute triangle or the acute isosceles triangle, that is, the angle of the apex (α in FIG. 1E) is preferably, for example, 30 ° or more and less than 90 °. By setting such a range, the space and area occupied by the dividing member 13 can be reduced, the height of the dividing member 13 can be reduced, and the light emitting device can be made smaller and thinner.
The pitch P between the top portions 13a of the dividing member 13 can be appropriately adjusted depending on the size of the light source used, the size and performance of the intended light emitting device, and the like. For example, 1 mm to 50 mm is mentioned, 5 mm to 20 mm is preferable, and 6 mm to 15 mm is more preferable.

The inclined surface 13b of the wall portion 13A surrounding the light source 11 is preferably formed by an inclined surface so as to spread from the vicinity of the bottom surface 13c and the upper surface of the substrate 12 toward the upper surface. The angle of the wall portion 13A (γ in FIG. 1E) may be, for example, 45 ° to 60 °. Further, for example, as shown in FIG. 4, the inclined surface may have an upper inclined surface 13b1 (U) and a lower inclined surface 13b2 (L) having different inclination angles in the vertical direction. The angles of these inclined surfaces can be appropriately set within the above range. For example, the angle of the upper inclined surface 13b1 (an angle equivalent to γ in FIG. 1E) may be smaller than the angle of the lower inclined surface 13b2, but as shown in FIG. 4, the angle of the upper inclined surface 13b1 is the lower part. It is preferably larger than the angle of the inclined surface 13b2.
The height of the dividing member 13 itself, that is, the length from the lower surface of the bottom surface 13c of the dividing member 13 to the top 13a is preferably 8 mm or less, and preferably about 1 mm to 4 mm in the case of a thinner light emitting device. The distance to the plate 14 is preferably about 8 mm or less, and when a thinner light emitting device is used, it is preferably about 2 mm to 4 mm. As a result, the backlight unit including the optical member such as the diffuser plate 14 can be made extremely thin.
The thickness of the dividing member 13 may be constant or may vary depending on the portion, but it is preferable that the dividing member 13 constituting the upper inclined surface is thinner than the dividing member 13 constituting the lower inclined surface. The thickness of the dividing member 13 may be, for example, 100 μm to 300 μm.

The shape of the division C formed by the division member 13 surrounding the light source 11, that is, the shape of the region divided by the wall portion 13A may be, for example, a circular shape, an elliptical shape, or the like in a plan view, but a plurality of shapes may be formed. In order to efficiently arrange the light source, a polygon such as a triangle, a quadrangle, or a hexagon is preferable. As a result, it becomes easy to divide the light emitting area into an arbitrary number by the wall portion 13A according to the area of the light emitting surface of the surface light emitting device, and the light emitting area can be arranged at a high density. The number of divisions C classified by the wall portion 13A can be arbitrarily set, and the shape and arrangement of the wall portion 13A, the number of divisions C, and the like can be changed according to the desired size of the light emitting device.
The division member 13 is shown in FIG. 1B in a plan view, for example, in which three divisions C are adjacent to each other and the ends of the three tops are concentrated at one point, depending on the number and position of the light sources 11 arranged on the substrate 12. As described above, various shapes can be obtained, such as those in which the four divisions C are adjacent to each other and the four tops are concentrated, and those in which the six divisions C are adjacent to each other and the six tops are concentrated at one point.

The dividing member 13 is preferably arranged on the substrate 12, and preferably the lower surface of the bottom surface 13c of the dividing member 13 and the upper surface of the substrate 12 are fixed. In particular, it is preferable to fix the periphery of the through hole 13d with a light-reflecting adhesive member so that the light emitted from the light source 11 does not enter between the substrate 12 and the dividing member 13. For example, it is more preferable to arrange the light-reflecting adhesive member in a ring shape along the outer edge of the through hole 13d. The adhesive member may be a double-sided tape, a hot melt type adhesive sheet, or a resin-based adhesive such as a thermosetting resin and a thermoplastic resin. These adhesive members preferably have high flame retardancy. However, screwing or the like may be used to fix the dividing member 13 on the substrate 12.

The dividing member 13 is preferably a member having reflectivity. As a result, the light emitted from the light source 11 can be efficiently reflected by the wall portion 13A and the bottom surface 13c. In particular, when the wall portion 13A has an inclination as described above, the light emitted from the light source 11 is applied to the wall portion 13A, and the light can be reflected upward. Therefore, even when the adjacent division C is not lit, the contrast ratio can be further improved. In addition, the light can be reflected upward more efficiently.
The classification member 13 may be molded using a resin containing a reflective material composed of metal oxide particles such as titanium oxide, aluminum oxide, and silicon oxide, or after molding using a resin not containing a reflective material. , A reflective material may be provided on the surface. It is preferable that the reflectance with respect to the light emitted from the light source 11 is set to be 70% or more.

The dividing member 13 can be formed by molding using a mold, a molding method by stereolithography, or the like. 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 vacuum forming using a reflective sheet formed of PET or the like, it is possible to form a dividing member 13 in which the bottom surface 13c and the wall portion 13A are integrally formed.
The division member 13 arranges a plurality of divisions C in a row direction, a column direction, or a matrix. For example, as shown in FIG. 1B, each light source 11 is surrounded by a wall portion 13A on a substrate in which five light sources 11 are arranged in the X direction, five in the Y direction, and a total of 25 light sources are arranged in a matrix, and the upper surface thereof is formed. Twenty-five divisions C having a substantially square view are defined, and it is possible to have a through hole 13d for mounting the light source 11 on the bottom surface 13c at the substantially center of the division C.

(Diffusion plate 14)
The diffuser plate 14 is a member that diffuses and transmits incident light, and it is preferable to arrange one above the plurality of light sources 11. The diffusion plate 14 has a first convex portion 14a surrounding the light source 11 in a region M on a surface facing the substrate 12 and overlapping the inclined surface 13b in a plan view. As described above, when the inclined surface 13b has an upper inclined surface and a lower inclined surface, it is preferable that the first convex portion is provided in a region overlapping the upper inclined surface in a plan view. In other words, the first convex portion may be arranged in the central portion of the region M overlapping the inclined surface 13b in a plan view, but it is preferable that the first convex portion is unevenly distributed closer to the top portion 13a. In the present specification, the surrounding may be one that continuously and completely surrounds the light source 11, or one that is divided into a plurality of parts and surrounds the light source 11.

The first convex portion 14a follows the shape of the division C, that is, when the shape of the region divided by the wall portion 13A is a polygon such as a triangle, a quadrangle, or a hexagon in a plan view. It is preferable to form a polygonal shape. For example, as shown in FIG. 1B, when the wall portions 13A constituting one section are arranged in a quadrangle so as to surround the light source 11, the first convex portion 14a is continuous or divided. Then, the one arranged in a quadrangular ring can be mentioned.
The height (thickness, T in FIG. 1E) of the first convex portion 14a is 5% to 30% of the thickness of the thinnest portion of the diffusion plate constituting one section (for example, t in FIG. 1E). It can be, preferably 9% to 20%. The width of the first convex portion 14a (FIG. 1E, W in FIG. 1E) may be 10% to 90% of the width of the region M, preferably 20% to 70%. For example, the thickness of the diffusion plate 14 is such that the thickness t of the thinnest portion in the division is 0.2 mm to 5 mm, preferably 0.5 mm to 2 mm, and the height T of the first convex portion 14a is 0.05 mm to 2 mm. The width W of the first convex portion 14a is preferably 0.1 mm to 0.6 mm, and the width W of the first convex portion 14a is preferably 0.1 mm to 1 mm, preferably 0.2 mm to 0.7 mm.

The first convex portion 14a may have various shapes such as a dome shape, a ridge shape, a columnar shape, and a frustum shape. For example, the first convex portion 14a has a symmetrical cross-sectional shape along the center line of the first convex portion. Is preferable, and as shown in FIG. 1E and the like, those having a symmetrical dome shape are more preferable.

It is preferable that the diffuser plate 14 is arranged substantially parallel to the substrate 12. For example, the surface of the diffuser plate 14 on the light extraction surface side may have irregularities, but it is more preferable that the surface is flat and the surface is substantially parallel to the substrate 12. When it has irregularities, it can be, for example, 0.01 mm to 0.1 mm. The incident light can be diffused by the unevenness.

The diffuser plate 14 can be made of a material having less light absorption with respect to visible light, such as a polycarbonate resin, a polystyrene resin, an acrylic resin, and a polyethylene resin. In order to diffuse the incident light, the diffuser plate 14 may disperse materials having different refractive indexes in the diffuser plate 14.
As the material having a different refractive index, for example, a polycarbonate resin, an acrylic resin, or the like can be selected and used.
The thickness of the diffuser plate 14 and the degree of light diffusion can be appropriately set, and commercially available members such as a light diffusion sheet and a diffuser film can be used.

For example, as shown in FIGS. 2A to 2D, in addition to the first convex portions 34a and 44a, the diffusion plates 34 and 44 are on a surface facing the substrate 12 and in a region overlapping the light source 11 in a plan view. It may have the second convex portions 34b, 44b. The planar shape of the second convex portions 34b and 44b may be arranged only in the region overlapping the light source or in a shape corresponding thereto, or the region overlapping the light source is arranged in the center and has a similar shape corresponding to the region. be able to. Examples of the planar shape of the second convex portion include a circular shape, a polygonal shape, a polygonal shape with rounded corners, and the like. Further, the position of the outer edge of the second convex portion in the plan view can be, for example, a position surrounding the light source with an area of 110% or more when the area of the region overlapping the light source is 100%. The outer edge of the second convex portion is preferably separated from the first convex portion. Among them, the second convex portions 34b and 44b have a region overlapping with the light source 11 in the center and have a similar shape corresponding to the region, and the first convex portion is separated from the first convex portion by a distance D. It is preferable that the shape has a portion close to the portion, and it is more preferable that the outer edge thereof is circular as shown in FIG. 2C. For example, the size of the second convex portion in a plan view has a diameter (WW in FIG. 2D) of 10% to 80% of the pitch P and 30% to 70%. Specifically, 0.3 mm to 35 mm is mentioned, 1.5 mm to 15 mm is preferable, and 1.8 mm to 10 mm is more preferable. The distance D is, for example, 0 mm to 4 mm, and is preferably 1 mm to 3 mm.

The second convex portions 34b and 44b preferably have a shape in which the region overlapping with the light source has the thickest thickness, and more preferably a shape having the thickest wall directly above the center of the light source. For example, various shapes such as a bowl shape, a cone shape, a cone shape, and a columnar shape can be mentioned, but it is preferable that the center or substantially the center of the light source is a cone shape or a cone shape having the thickest wall thickness. In this case, the surface from the center or substantially the center of the light source toward the outer periphery thereof may be a curve convex toward the substrate side in a cross-sectional view, or a curve recessed toward the light extraction surface side as shown in FIG. 2A. It may be (34b) in FIGS. 2A and 2D, or it may be a straight line (44b in FIG. 2B) as shown in FIG. 2B. Further, the second convex portion preferably has a symmetrical cross-sectional shape passing through the thickest film.
The thickness of the diffuser plate in the thickest portion of the second convex portions 34b, 44b (TT in FIG. 2D) is the thickness of the thinnest portion of the diffuser plate constituting one section (for example, in FIGS. 1E and 2D, t). ) Can be 200% to 600%, preferably 400% to 600%. From another viewpoint, the thickness TT of the diffuser plate at the thickest portion of the second convex portion 34 is 2 mm to 5 mm, and is preferably 2 mm to 3.5 mm.

(Other parts)
The light emitting device of the present embodiment may include a reflective member or the like.
(Reflective member)
For example, on the upper surface of the diffuser plate 14, as shown in FIG. 3A, the first reflecting portion 26 may be arranged above the light source 11, preferably directly above the light source 11. As shown in FIG. 3B, the first reflecting portion 26 may be provided on the surface of the diffuser plate 14 facing the substrate. In the region above the light source 11, particularly in the region directly above, the distance between the diffuser plate 14 and the light source 11 is the shortest. Therefore, the brightness in this region becomes high. The shorter the distance between the diffuser plate 14 and the light source 11, the more remarkable the luminance unevenness with the region directly above the region where the light source 11 is not arranged. Therefore, by providing the first reflecting portion 26 on the surface of the diffuser plate 14, it is possible to alleviate the luminance unevenness by reflecting a part of the highly directional light of the light source 11 and returning it to the direction of the light source 11.

The first reflecting portion 26 can be formed of a material containing a light reflecting material. For example, a resin containing a light reflecting material and / or an organic solvent may be mentioned. Examples of the light reflecting material include metal oxide particles such as titanium oxide, aluminum oxide, and silicon oxide. The resin and the organic solvent can be appropriately selected in consideration of the metal oxide particles to be used, the characteristics required for the manufactured light emitting device, and the like. Among them, as the resin, it is preferable to use a translucent and photocurable resin containing an acrylate resin, an epoxy resin or the like as a main component.
The first reflecting unit 26 may further contain a pigment, a light absorber, a phosphor, or the like in the material constituting the first reflecting unit 26.
The first reflecting portion 26 can have various shapes or patterns such as a predetermined stripe shape and an island shape. The method for forming the first reflecting portion 26 may be any method known in the art, such as a printing method, an inkjet method, or a spraying method.
The thickness of the first reflective portion is, for example, 10 μm to 100 μm.

The light emitting device may be provided above the diffuser plate with at least one selected from the group consisting of a wavelength conversion sheet, a prism sheet, and a polarizing sheet that convert light from a light source into light having a different wavelength. Specifically, as shown in FIG. 3B, the wavelength conversion sheet 22 and the prism sheet (first prism sheet 23) are directly or indirectly above the diffuser plate 14 at a predetermined distance or on the upper surface of the diffuser plate 14. An optical member such as the second prism sheet 24) and the polarizing sheet 25 can be arranged, and a liquid crystal panel can be arranged on the optical member to form a surface emitting light emitting device used as a light source for a direct backlight. The stacking order of these optical members can be set arbitrarily.

(Wavelength conversion sheet 22)
The wavelength conversion sheet 22 may be arranged on either the upper surface or the lower surface of the diffuser plate 14, but it is preferably arranged on the upper surface as shown in FIG. 3B. The wavelength conversion sheet 22 absorbs a part of the light emitted from the light source 11 and emits light having a wavelength different from the wavelength of the light emitted from the light source 11. For example, the wavelength conversion sheet 22 can be a light emitting device that absorbs a part of the blue light from the light source 11 to emit yellow light, green light and / or red light, and emits white light. Since the wavelength conversion sheet 22 is separated from the light emitting element of the light source 11, it is possible to use a phosphor or the like having poor resistance to heat or light intensity, which is difficult to use in the vicinity of the light emitting element. This makes it possible to improve the performance of the light emitting device as a backlight. The wavelength conversion sheet 22 has a sheet shape or a layer shape, and includes the above-mentioned phosphor and the like.

(1st prism sheet 23 and 2nd prism sheet 24)
The first and second prism sheets 23 and 24 have a shape in which a plurality of prisms extending in a predetermined direction are arranged on the surface thereof. For example, the first prism sheet 23 has a plurality of prisms extending in the y direction when the plane of the sheet is viewed two-dimensionally in the x direction and the y direction perpendicular to the x direction, and the second prism sheet 24 has x. It can have a plurality of prisms extending in a direction. The prism sheet can refract light incident from various directions toward the display panel facing the light emitting device. As a result, the light emitted from the light emitting surface of the light emitting device can be emitted mainly in the direction perpendicular to the upper surface, and the brightness when the light emitting device is viewed from the front can be increased.

(Polarizing sheet 25)
The polarizing sheet 25 selectively transmits light in a polarization direction that matches the polarization direction of a display panel, for example, a polarizing plate arranged on the backlight side of a liquid crystal display panel, and is polarized in a direction perpendicular to the polarization direction. Can be reflected toward the first and second prism sheets 23 and 24. A part of the polarized light returned from the polarizing sheet 25 is reflected again by the first and second prism sheets 23 and 24, the wavelength conversion sheet 22, and the diffusing plate 14. At this time, the polarization direction changes, and for example, it is converted into polarization having the polarization direction of the polarizing plate of the liquid crystal display panel, is incident on the polarizing sheet 25 again, and is emitted to the display panel. As a result, the polarization directions of the light emitted from the light emitting device can be aligned, and the light in the polarization direction effective for improving the brightness of the display panel can be emitted with high efficiency. As the polarizing sheet 25, the first and second prism sheets 23, 24 and the like, commercially available optical members for the backlight can be used.

The light emitting device of the present invention can be used for various light emitting devices such as a light source for a backlight of a display device and a light source of a lighting device.

11 Light source 12 Substrate 13 Division member 13a Top 13b Wall 13b1 Upper inclined surface 13b2 Lower inclined surface 13c Bottom surface 13d Through hole 14, 34, 44 Diffuse plate 14a, 34a, 44a First convex part 34b, 44b Second convex part 15 Light emission Elements 18A, 18B Conductor wiring 19 Joining member 20 Light reflecting film 21 Encapsulating member 21a Underfill 22 Wavelength conversion sheet 23 1st prism sheet 24 2nd prism sheet 25 Polarizing sheet 26 1st reflecting part 28 Covering member

Claims (9)

A board with multiple light sources and
A division member that surrounds each of the light sources and has a wall portion having a top portion and an inclined surface, the area surrounded by the wall portion is defined as one division, and a plurality of the divisions are provided.
Located above the light source and on a surface facing the substrate.
Only in the region overlapping the inclined surface in the plan view, the light source has a first convex portion that surrounds the light source in a quadrangle in the plan view.
A light emitting device including a diffuser plate having a circular second convex portion whose outer edge surrounds the light source in a plan view, which is a region overlapping the light source in the plan view. The light emitting device according to claim 1, wherein the first convex portion has a thickness of 10% to 30% of the thinnest thickness of the diffuser plate. The light emitting device according to claim 1 or 2, wherein the first convex portion has a symmetrical cross-sectional shape along the center line of the first convex portion. The light emitting device according to any one of claims 1 to 3, wherein the one division is a quadrangle in a plan view, and the first convex portion is an annular shape of the quadrangle in a plan view within the one division. The inclined surface has an upper inclined surface and a lower inclined surface having different inclination angles in the vertical direction, and any of claims 1 to 4 having the first convex portion in a region overlapping the upper inclined surface in a plan view. The light emitting device according to item 1. The light emitting device according to any one of claims 1 to 5, wherein the second convex portion has an outer edge isolated from the first convex portion. The light emitting device according to claim 6, wherein the second convex portion has a thickness of 400% to 600% of the thinnest thickness of the diffuser plate. The light emitting device according to claim 6 or 7, wherein the second convex portion is a thickest film directly above the center of the light source. The light emitting device according to claim 8, wherein the second convex portion has a symmetrical cross-sectional shape passing through the thickest film.

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