JP2021166133A - Planar light source and planar light source manufacturing method - Google Patents

Abstract

To provide a planar light source and a planar light source manufacturing method capable of reducing light absorption near a light source.SOLUTION: A planar light source includes: a wiring board; a light guide plate which is arranged on the wiring board and includes a first main surface, a second main surface, and a first hole part penetrating from the first main surface to the second main surface; a light source which is arranged on the wiring board located in the first hole part; a first light reflective member which is arranged on the wiring board located between an inner side surface of the first hole part and a side surface of the light source in a plan view; and a second light reflective member which is arranged on a second main surface side of the light guide plate. The diffuse reflectance of light emitted by the light source of the first light reflective member is higher than the diffuse reflectance of light emitted by the light source of the second light reflective member.SELECTED DRAWING: Figure 2

Description

The present invention relates to a planar light source and a method for manufacturing a planar light source.

A light emitting module in which a light emitting element such as a light emitting diode and a light guide plate are combined is widely used as a planar light source such as a backlight of a liquid crystal display. For example, Patent Document 1 discloses a structure including a light guide plate, a light source arranged in a through hole formed in the light guide plate, and a reflection member arranged on the light source.

Korean Publication No. 10-2009-0117419

An object of the present invention is to provide a planar light source and a method for manufacturing a planar light source capable of reducing light absorption in the vicinity of the light source.

According to one aspect of the present invention, the planar light source is a wiring board and a light guide plate arranged on the wiring board, which is opposite to the first main surface and the first main surface. A light source including a second main surface arranged to face the wiring board, a first hole portion penetrating from the first main surface to the second main surface, and the wiring located in the first hole portion. A light source arranged on a substrate, a first light reflective member arranged on the wiring board located between the inner side surface of the first hole portion and the side surface of the light source in a plan view, and the light guide plate. A second light-reflecting member arranged on the second main surface side of the above. The diffuse reflectance of the first light-reflecting member with respect to the light emitted by the light source is higher than the diffuse reflectance of the second light-reflecting member with respect to the light emitted by the light source.

According to one aspect of the present invention, the method for manufacturing a planar light source is a wiring substrate and a light guide plate arranged on the wiring substrate, on the first main surface and the opposite side of the first main surface. A light guide plate including a second main surface arranged to face the wiring board and a first hole portion penetrating from the first main surface to the second main surface, and located in the first hole portion. A step of preparing a structure including a light source arranged on the wiring substrate, a step of supplying a liquid containing a light diffusing agent, a translucent resin, and a solvent to the first hole portion, and the above-mentioned step. A light-reflecting member containing the light diffusing agent and the translucent resin on the wiring substrate located between the inner side surface of the first hole portion and the side surface of the light source in a plan view by evaporating the solvent. It is provided with a step of forming the above.

It is possible to reduce the light absorption in the light emitting surface in the vicinity of the light source.

It is a schematic plan view of the planar light source of one Embodiment of this invention. FIG. 5 is a schematic cross-sectional view taken along the line II-II of FIG. It is a schematic cross-sectional view of the light source of one Embodiment of this invention. It is a schematic cross-sectional view of the light source of another embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the laminated body of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the laminated body of one Embodiment of this invention. It is a schematic plan view which shows the manufacturing method of the laminated body of one Embodiment of this invention. It is a schematic plan view which shows the manufacturing method of the laminated body of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic plan view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic plan view which shows the manufacturing method of the planar light source of one Embodiment of this invention. It is a schematic cross-sectional view of a part of the planar light source of another embodiment of this invention.

Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same elements are designated by the same reference numerals.

FIG. 1 is a schematic plan view of a planar light source 100 according to an embodiment of the present invention. FIG. 1 shows a plan view of the light emitting surface of the planar light source 100. In FIG. 1, two directions parallel to the light emitting surface of the planar light source 100 and orthogonal to each other are defined as the X direction and the Y direction.

The planar light source 100 may include one or more light sources 20. When the planar light source 100 includes a plurality of light sources 20, each light source 20 is partitioned by a partition groove 14. This partitioned area is also referred to as a light emitting area 1. Further, in the case of a planar light source including one light source 20, one planar light source includes one light emitting region. As described above, by arranging a plurality of planar light sources including one light source 20 and a plurality of planar light sources 100 including a plurality of light sources 20, a planar light source device having a larger area can be obtained.

The planar light source 100 shown in FIG. 1 has a quadrangular outer shape having two sides extending along the X direction and two sides extending along the Y direction.

One light emitting region 1 can be, for example, a drive unit for local dimming. FIG. 1 illustrates a planar light source 100 having six light emitting regions 1 partitioned in 2 rows and 3 columns. The number of light emitting regions 1 constituting the planar light source 100 is not limited to the number shown in FIG.

FIG. 2 is a schematic cross-sectional view taken along the line II-II of FIG. 1, and represents a schematic cross section of a portion including one light source 20. The planar light source 100 includes a wiring board 50, a laminated structure 111, and a light source 20.

The laminated structure 111 includes a light guide plate 10 and a second light reflecting member 41. As shown in FIG. 5, the light guide plate 10 includes a first hole portion 15. The second light reflecting member 41 includes a second hole portion 41a at a position overlapping the first hole portion 15. That is, the laminated structure 111 includes a through hole 13 including a first hole portion 15 and a second hole portion 41a. The first hole portion 15 and the second hole portion 41a can have the same width (diameter). Alternatively, the width (diameter) of the first hole portion 15 can be larger or smaller than the width (diameter) of the second hole portion 41a.

The inner surface of the first hole portion 15 and the second hole portion 41a may be a surface perpendicular to the first main surface 11 or the second main surface 12 of the light guide plate 10 or an inclined surface inclined. .. Further, the inner side surfaces of the first hole portion 15 and the second hole portion 41a have a shape in which a surface perpendicular to the first main surface 11 or the second main surface 12 of the light guide plate 10 or an inclined surface that is inclined is combined. Can be.

The first hole portion 15 and the second hole portion 41a can be circular or elliptical in a plan view. The first hole portion 15 and the second hole portion 41a can be made into a square shape such as a triangle, a quadrangle, a hexagon, or an octagon in a plan view. It is preferable that the centers of the first hole portion 15 and the second hole portion 41a coincide with each other in a plan view.

The light guide plate 10 has translucency with respect to the light emitted by the light source 20. The light source 20 has a light emitting element 21. The light emitted by the light source 20 represents the light emitted by the light emitting element 21. When the light source 20 includes a phosphor, the light emitted by the light source 20 also includes the light emitted by the phosphor. The transmittance of the light guide plate 10 with respect to the light from the light source 20 is, for example, preferably 80% or more, and more preferably 90% or more.

As the material of the light guide plate 10, for example, acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, thermoplastic resin such as polyester, epoxy, thermosetting resin such as silicone, glass or the like can be used. ..

The light guide plate 10 has a first main surface 11 that serves as a light emitting surface of the planar light source 100, and a second main surface 12 on the opposite side of the first main surface 11. As described above with reference to FIG. 5, the light guide plate 10 has a first hole portion 15 penetrating from the first main surface 11 to the second main surface 12.

The thickness of the light guide plate 10 is preferably 200 μm or more and 800 μm or less, for example. The light guide plate 10 may be composed of a single layer or a laminated body of a plurality of layers in the thickness direction thereof. When the light guide plate 10 is composed of a laminated body, a translucent adhesive member may be arranged between the layers. Different types of main materials may be used for each layer of the laminate. As the material of the adhesive member, for example, acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, a thermoplastic resin such as polyester, an epoxy, or a thermosetting resin such as silicone can be used.

One planar light source 100 can include a plurality of light sources 20. That is, one light guide plate 10 can include a plurality of first hole portions 15. In that case, as shown in FIG. 1, the light guide plate 10 preferably includes a grid-like partition groove 14 composed of a partition groove 14 extending linearly in the X direction and a partition groove 14 extending in the Y direction. .. The partition groove 14 partitions each light emitting region 1. In other words, the region surrounded by the partition groove 14 is one light emitting region 1.

FIG. 2 illustrates a bottomed partition groove 14 having an opening on the first main surface 11 side and whose bottom does not reach the second main surface 12. In the case of the partition groove 14, the position of the bottom can be any position in the thickness direction of the light guide plate 10. For example, when it is desired to suppress light leakage to the adjacent light emitting region 1, 50% or more, more preferably 70%, and particularly preferably 90% or more of the thickness of the light guide plate 10. That is, it is preferable that the bottom of the partition groove 14 is close to the second main surface 12.

Further, the partition groove 14 may be a bottomed groove having an opening on the second main surface 12 side and whose bottom does not reach the first main surface 11.

The partition groove 14 may be separated from the first main surface 11 and the second main surface 12. For example, the light guide plate 10 uses a laminated structure in which two plates, a first light guide plate including a surface to be the first main surface 11 and a second light guide plate including a surface to be the second main surface 12, are laminated. be able to. The lower surface of the first light guide plate is provided with a bottomed first groove, and the upper surface of the second light guide plate is provided with a bottomed second groove. Then, by arranging the first groove and the second groove so as to overlap each other in a plan view, the first groove and the second groove are formed at positions separated from the first main surface 11 and the second main surface 12. It can be a light guide plate provided with a partition groove to be formed.

Further, the partition groove 14 may penetrate from the first main surface 11 to the second main surface 12. Further, the partition groove penetrating the light guide plate 10 may be connected to the groove arranged in the second light reflective member 41 constituting the laminated structure 111 together with the light guide plate 10. That is, it can be a partition groove including a through groove penetrating the light guide plate 10 and a bottomed through groove arranged in the second light reflecting member 41.

The plan-view shape of the partition groove 14 can be determined by the shape of the light emitting region 1. For example, when the adjacent light emitting regions 1 are quadrangular, the partition grooves 14 arranged between them have a linear shape having a constant width in a plan view. The width of the partition groove 14 can be, for example, 0.2% to 10%, more preferably 3% to 7% of the width of the light emitting region 1. When the third light-reflecting member 42 is arranged in the partition groove 14, it is preferable that the partition groove 14 has an opening width in which the third light-reflecting member 42 can be arranged. For example, when a resin member containing a light diffusing agent is used as the third light-reflecting member 42, the opening width of the partition groove 14 can be appropriately selected according to the viscosity of the resin member and the like. In particular, when the content of the light diffusing agent is increased in order to increase the reflectance of the third light reflecting member 42, the viscosity of the third light reflecting member 42 tends to be increased. Therefore, if the opening width of the partition groove 14 is too narrow, it becomes difficult to arrange the third light reflecting member 42 at an appropriate position on the inner surface of the partition groove 14. In such a case, it is preferable to use a partition groove 14 having an appropriately wide opening width.

As shown in FIG. 2, the third light reflecting member 42 can be arranged in the partition groove 14. The third light-reflecting member 42 preferably has reflectivity to the light emitted by the light source 20. As the third light-reflecting member 42, for example, a white resin member containing a light diffusing agent can be used. Examples of the light diffusing agent include fine particles such as _{TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO.} Further, as the third light-reflecting member 42, a light-reflective metal member such as Al or Ag may be used. Further, a member having a refractive index lower than that of the light guide plate 10 may be arranged in the partition groove 14. Examples of the member having a low refractive index include air and the like.

When the third light reflective member 42 is arranged in the partition groove 14, for example, as shown in FIG. 2, it can be arranged so as to follow the shape of the inner side surface of the partition groove 14. In other words, a part of the upper surface of the third light reflective member 42 can be arranged so as to be lower than the first main surface 11 of the light guide plate 10. Here, an example is shown in which the cross section of the partition groove 14 is V-shaped, and the cross section of the third light reflecting member 42 is also V-shaped. Further, it is preferable that the third light reflecting member 42 is arranged so as to cover the entire inner side surface of the partition groove 14.

Further, the third light reflecting member 42 arranged in the partition groove 14 can be formed so as to fill the entire space in the partition groove 14.

Further, the third light reflective member 42 may include a portion extending from the inside of the partition groove 14 onto the first main surface 11 of the light guide plate 10.

The third light reflective member 42 suppresses the light guide between the adjacent light emitting regions 1. For example, the light guide from the light emitting region 1 in the light emitting state to the light emitting region 1 in the non-light emitting state is restricted. This enables local dimming with each light emitting region 1 as a drive unit.

The light source 20 is arranged on the wiring board 50 in the through hole 13 of the laminated structure 111. The second light reflective member 41 is arranged on the second main surface 12 of the light guide plate 10.

The laminated structure 111 is arranged on the wiring board 50. The second main surface 12 of the light guide plate 10 faces the wiring board 50, and the second light reflective member 41 is arranged between the second main surface 12 and the wiring board 50.

The second light-reflecting member 41 has reflectivity to the light emitted by the light source 20. For example, as the second light-reflecting member 41, a sheet-shaped resin member can be used. As the second light-reflecting member 41, a white resin member containing a large number of bubbles can be used. Alternatively, as the second light-reflecting member 41, a white resin member containing a light diffusing agent can be used. Examples of the light diffusing agent include fine particles such as _{TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO.} As the resin material contained in the second light-reflecting member 41, for example, a thermoplastic resin such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate and polyester, a thermosetting resin such as epoxy and silicone, and the like can be used.

The second light reflective member 41 is adhered to the wiring board 50 via the adhesive layer 62. The adhesive layer 62 is, for example, a resin layer such as an epoxy resin, an acrylic resin, or an olefin resin. That is, the light guide plate 10 is arranged on the wiring board 50 via the adhesive layer 62 and the second light reflective member 41.

FIG. 3A is a schematic cross-sectional view showing an example of the light source 20.

The light source 20 includes a light emitting element 21 and a first translucent member 22. The light source 20 may further include at least one of a covering member 24 and a first light adjusting member 25.

The light emitting element 21 has a semiconductor laminate 29 and a pair of positive and negative electrodes 23. The light emitting element 21 can emit ultraviolet light or visible light. The light emitting element 21 can emit light from blue to red as visible light. As the semiconductor laminate 29, for example, In _x Al _y Ga _1-x-y N (0 ≦ x, 0 ≦ y, x + y ≦ 1) can be included.

The semiconductor laminate 29 of the light emitting element 21 includes an element upper surface 21a, an element lower surface 21b, and an element side surface 21c between the element upper surface 21a and the element lower surface 21b. The pair of positive and negative electrodes 23 are arranged on the lower surface 21b of the element. The pair of positive and negative electrodes 23 may be arranged on the upper surface 21a of the element.

The first translucent member 22 covers the element upper surface 21a and the element side surface 21c of the light emitting element 21. The first translucent member 22 has a translucent resin and a phosphor dispersed and contained in the translucent resin. The translucent resin is, for example, a silicone resin or an epoxy resin. The phosphor is a wavelength conversion substance that is excited by the light emitted by the light emitting element 21 and emits light having a wavelength different from the wavelength of the light emitted by the light emitting element 21. For example, as phosphors, ittrium-aluminum-garnet-based phosphors (Y ₃ (Al, Ga) ₅ O ₁₂ : Ce) and lutetium-aluminum-garnet-based phosphors (Lu ₃ (Al, Ga) ₅ O ₁₂ : Ce) ), Terbium-aluminum-garnet-based phosphor (Tb ₃ (Al, Ga) ₅ O ₁₂ : Ce) -based phosphor, β-sialon-based phosphor (Si _6-z Al _z O _z N _8-z : Eu (0) <Z <4.2)), α-sialon-based phosphor (Mz (Si, Al) ₁₂ (O, N) ₁₆ (where 0 <z ≦ 2 and M is Li, Mg, Ca, Y, and Lantanide elements excluding La and Ce), nitride phosphors such as nitrogen-containing calcium aluminosilicate (CASN or SCASN) phosphors (for example, (Sr, Ca) AlSiN ₃ : Eu), KSF phosphors (K ₂ SiF ₆₎ : Mn) or fluoride-based fluorescent materials such as MGF-based phosphors (3.5 MgO, 0.5 MgF ₂ , GeO ₂ : Mn), silicate-based fluorescent materials (for example, (Ba, Sr) ₂ SiO ₄ : Eu), chloro A nitride phosphor such as a silicate-based phosphor (for example, Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu) can be used. The first translucent member 22 contains a plurality of types of phosphors. Further, the first translucent member 22 may have a configuration in which a plurality of layers of different types of phosphors are laminated.

The light source 20 may include a covering member 24. The covering member 24 is arranged on the element lower surface 21b of the light emitting element 21. The covering member 24 is arranged so that at least a part of the surface (lower surface in FIG. 3A) of the electrode 23 is exposed from the covering member 24. The covering member 24 can also be arranged on the lower surface of the first translucent member 22 that covers the element side surface 21c of the light emitting element 21.

The covering member 24 has reflectivity to the light emitted by the light source 20. The covering member 24 is, for example, a white resin member containing a light diffusing agent. Examples of the light diffusing agent include fine particles such as _{TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO.}

The light source 20 may include a first light adjusting member 25. The first light adjusting member 25 is arranged on the upper surface of the first translucent member 22. The first light adjusting member 25 is arranged so as to cover the upper surface of the first translucent member 22. The first light adjusting member 25 has reflectivity and translucency with respect to the light emitted by the light emitting element 21 and the phosphor.

The first light adjusting member 25 can have a translucent resin and a light diffusing agent dispersed and contained in the translucent resin. The translucent resin is, for example, a silicone resin or an epoxy resin. Examples of the light diffusing agent include fine particles such as _{TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO.} The first light adjusting member 25 may be, for example, a light-reflecting metal member such as Al or Ag, or a DBR (Distributed Bragg Reflector).

As shown in FIG. 2, the first light reflecting member 31a is arranged on the wiring board 50 around the light source 20 in the through hole 13. The first light-reflecting member 31a has reflectivity to the light emitted by the light source 20. The first light-reflecting member 31a is, for example, a white resin member containing fine particles such _{as TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO as a light diffusing agent.}

As shown in FIG. 1, the first light reflecting member 31a is arranged on the wiring board 50 between the inner side surface 13a of the through hole 13 and the side surface 20a of the light source 20 in a plan view.

The fourth light reflective member 31b may be arranged on the upper surface of the light source 20. As will be described later, the fourth light-reflecting member 31b and the first light-reflecting member 31a can be formed of the same material and at the same time by utilizing the evaporation of the solvent.

The second translucent member 70 is arranged in the through hole 13 of the laminated structure 111. The second translucent member 70 has translucency with respect to the light emitted by the light source 20, and uses, for example, the same resin as the material of the light guide plate 10 or a resin having a small difference in refractive index from the material of the light guide plate 10. Can be done. Glass may be used as the material of the second translucent member 70.

The second translucent member 70 is arranged between the side surface 20a of the light source 20 and the inner side surface 13a of the through hole 13. Arranged so that a space such as an air layer is not formed between the side surface 20a of the light source 20 and the second translucent member 70, and between the inner side surface 13a of the through hole 13 and the second translucent member 70. can do.

The second light-transmitting member 70 is arranged on the first light-reflective member 31a and the fourth light-reflective member 31b, and covers the first light-reflective member 31a and the fourth light-reflective member 31b. The upper surface of the second translucent member 70 can be a flat surface. Alternatively, the upper surface of the second translucent member 70 can be a concave or convex curved surface. The second translucent member 70 can come into contact with the entire inner surface of the through hole 13. Alternatively, the second translucent member 70 can be arranged so that a part of the inner side surface of the first hole portion 15 of the light guide plate 10 is exposed. Further, the second translucent member 70 may include a portion extending from the inside of the through hole 13 onto the first main surface 11 of the light guide plate 10.

The wiring board 50 includes an insulating base material 51 and a wiring layer 52 arranged on the insulating base material 51. The wiring board 50 may further include an insulating coating layer 53 that covers the wiring layer 52. Further, the wiring board 50 can include a pad portion 54 that is electrically connected to the wiring layer 52. The insulating base material 51 and the coating layer 53 can contain, for example, resins such as polyimide, polyethylene naphthalate, and polyethylene terephthalate. The wiring layer 52 and the pad 54 may include a metal material such as copper or aluminum.

The electrode 23 of the light source 20 is joined to the pad 54 via the conductive joining member 61. For the joining member 61, for example, solder such as Au-Sn, Au-Ag-Cu, and Au-Bi can be used.

The second translucent member 70 may be arranged between the light source 20 and the wiring board 50, and also around the joining member 61.

A second light adjusting member 80 is arranged on the second light transmissive member 70. The second light adjusting member 80 has reflectivity and translucency to the light emitted by the light source 20. The second light adjusting member 80 can be a resin member containing a light diffusing agent. The second light adjusting member 80 can be arranged so as to cover all or a part of the upper surface of the second light transmissive member 70. The second light adjusting member 80 is preferably arranged at a position overlapping the light source 20 in a plan view. In the examples shown in FIGS. 1 and 2, the second light adjusting member 80 is arranged at a position overlapping the light source 20 in a plan view. Further, as shown in FIG. 1, the second light adjusting member 80 is a quadrangle having a plan view larger than that of the quadrangular light source 20. The second light adjusting member 80 may have a shape such as a circle, a triangle, a hexagon, or an octagon in a plan view. Further, the second light adjusting member 80 may be extended to the upper surface of the second translucent member 70 and the first main surface 11 of the light guide plate 10 around the upper surface of the second light transmissive member 70. Examples of the second light adjusting member 80 light diffusing agent include _{fine particles such as TiO 2} , SiO ₂ , Al ₂ O ₃ , and ZnO.

A second translucent member 70 is arranged between the first light adjusting member 25 and the second light adjusting member 80. The second translucent member 70 has a higher transmittance for the light emitted by the light source 20 than the first light adjusting member 25 and the second light adjusting member 80. The transmittance of the second translucent member 70 with respect to the light emitted by the light source 20 can be 2 to 100 times the transmittance of the first light adjusting member 25 and the second light adjusting member 80.

The first light adjusting member 25 diffusely reflects a part of the light emitted in the direction directly above the light source 20 and transmits the other part. As a result, in each light emitting region 1 of the planar light source 100, it is possible to prevent the brightness of the region directly above the light source 20 from becoming extremely high as compared with the brightness of the other regions. That is, it is possible to reduce the uneven brightness of the light emitted from one light emitting region 1 partitioned by the partition groove 14.

When the fourth light-reflecting member 31b is formed on the first light adjusting member 25, the fourth light-reflecting member 31b also diffusely reflects a part of the light emitted in the direction directly above the light source 20. It functions as a light adjusting member that transmits other parts. The second light-transmitting member 70 has a higher transmittance for the light emitted by the light source 20 than the fourth light-reflecting member 31b.

Further, in the present embodiment, the second light adjusting member 80 can be arranged on the second translucent member 70 so as to be separated from the first light adjusting member 25. In other words, a second translucent member 70 having a higher transmittance than the first light adjusting member 25 and the second light adjusting member 80 is interposed between the first light adjusting member 25 and the second light adjusting member 80. ing. The light emitted from the light source 20 and the light emitted from the light source 20 and reflected by the first light reflecting member 31a around the light source 20 are reflected by the second translucent member 70 between the first light adjusting member 25 and the second light adjusting member 80. Light is guided. A part of the light guided to the second light transmissive member 70 is diffusely reflected by the second light adjusting member 80, and the other part is transmitted through the second light adjusting member 80. As a result, the region directly above the light source 20 is not too bright and not too dark, and as a result, the uneven brightness in the light emitting surface of the light emitting region can be reduced.

In the covering member 24 arranged on the lower surface of the light source 20 and the first light reflective member 31a arranged on the wiring board 50 around the light source 20, the wiring board 50 in the vicinity of the light source 20 is emitted from the light source 20. It is possible to suppress exposure to light and prevent deterioration of the wiring board 50. Further, the covering member 24 and the first light reflecting member 31a reflect the light directed from the light source 20 toward the second main surface 12 side to the first main surface 11 side which is the light emitting surface of the planar light source 100, and the first 1 The brightness of the light extracted from the main surface 11 is improved.

For example, the second light-reflecting member 41 is a resin member containing air bubbles and does not contain a light diffusing agent. Alternatively, the content of the light diffusing agent (weight percent) in the second light reflecting member 41 is lower than the content of the light diffusing agent (weight percent) in the first light reflecting member 31a. The diffuse reflectance of the first light-reflecting member 31a with respect to the light emitted by the light source 20 is higher than the diffuse reflectance of the second light-reflecting member 41 with respect to the light emitted by the light source 20. Further, the normal reflectance of the second light-reflecting member 41 located away from the light source 20 is higher than the normal reflectance of the first light-reflecting member 31a located in the vicinity of the light source 20.

By arranging the first light reflecting member 31a having a high diffuse reflectance in the vicinity of the light source 20, the light emitted to the outside from the vicinity of the light source 20 can be brightened. Further, by arranging the second light reflecting portion 41 having a high specular reflectance at a position away from the light source 20, the light emitted to the outside from between the light sources 20 can be brightened. Diffuse reflectance and specular reflectance can be measured by, for example, a high-speed spectrocolorimeter (CMS-35SP) manufactured by Murakami Color Technology Laboratory.

The first light-reflecting member 31a, which has higher diffuse reflectance, can suppress the brightness concentration around the light source 20.

In the region between the second light-reflecting member 41 arranged on the second main surface 12 of the light guide plate 10 and the first main surface 11, the reflection by the second light-reflecting member 41 and the first main surface While the reflection at 11 is repeated, the light from the light source 20 is guided in the light guide plate 10 toward the partition groove 14. In the region between the second light reflecting member 41 and the first main surface 11, a part of the light directed to the first main surface 11 is taken out from the first main surface 11 to the outside of the light guide plate 10.

As the second light-reflecting member 41, a member having a lower diffuse reflectance than the first light-reflecting member 31a, in other words, a member having a high specular reflectivity, is used to guide light to a region farther from the light source 20. It can be done easily. Even if the distance between the light source 20 and the end portion (partition groove 14) of each light emitting region 1 or the distance between the plurality of light sources 20 becomes long, it is easy to guide the light to the entire region of the light emitting region 1. Become. This can reduce the uneven brightness in the light emitting surface (first main surface 11). In addition, the number of light sources 20 arranged on the light guide plate 10 can be reduced.

Next, a method of manufacturing the planar light source 100 will be described.

The method for manufacturing the planar light source 100 of the embodiment includes a step of preparing the structure 400 shown in FIG. The structure 400 can be prepared by purchase. Alternatively, the structure 400 can be prepared by going through some steps.

When the structure 400 is manufactured and prepared, the following steps can be mentioned.
1) Step to prepare the laminated structure 2) Step to prepare the wiring board 3) Step to prepare the light source

1) Step of preparing the laminated structure 111 FIGS. 4 and 5 are schematic cross-sectional views showing a step of preparing the laminated structure 111, and FIGS. 6A and 6B show a step of preparing the laminated structure 111. It is a schematic plan view. 6A represents the top view of FIG. 4, and FIG. 6B represents the top view of FIG.

The step of preparing the laminated structure 111 includes a step of preparing the first laminated structure 110 as shown in FIGS. 4 and 6A. The first laminated structure 110 includes a first light guide plate 10'including a first main surface 11 and a second main surface 12 on the opposite side of the first main surface 11, and a second main surface of the first light guide plate 10'. Includes a second light-reflecting member 41'arranged on the surface 12.

As shown in FIGS. 5 and 6B, a through hole 13 including a first hole portion 15 and a second hole portion 41a is formed in the first laminated structure 110. As a result, a laminated structure including a light guide plate 10 on which the first hole portion 15 is formed and a second light reflective member 41 arranged on the second main surface 12 of the light guide plate 10 and having the second hole portion 41a. 111 is obtained.

The first hole portion 15 penetrates the light guide plate 10. The second hole portion 41a is arranged at the same position (overlapping position) as the first hole portion 15 of the light guide plate 10 in a plan view, and penetrates the second light reflecting member 41.

The laminated structure 111 provided with the through hole 13 may be purchased and prepared. Further, the laminated structure 111 may be prepared by purchasing the first laminated structure 110 having no through hole and performing the step of forming the through hole 13. Alternatively, a first light guide plate 10'which does not have the first hole portion 15 or a second light reflecting member 41' which does not have the second hole portion 41a is purchased, and they are laminated to form the first laminated structure 110. The laminated structure 111 may be prepared by performing the step of forming and forming the through hole 13.

Next, the wiring board 50 is prepared. Then, as shown in FIG. 7, the joining member 61 is supplied on the pad 54 of the wiring board 50. As the joining member 61, for example, solder is supplied by a method such as printing or a jet dispenser.

The light source 20 is prepared. The light source 20 can be purchased and prepared. Alternatively, it can be prepared by going through a part or all of known steps using the members constituting the light source 20.

As shown in FIG. 8, the light source 20 is arranged on the wiring board 50 so that the electrode 23 of the light emitting element 21 is in contact with the joining member 61. In this state, the joining member 61 is melted in the reflow furnace, and the electrode 23 of the light emitting element 21 and the pad 54 of the wiring board 50 are connected.

After arranging the light source 20 on the wiring board 50, the laminated structure 111 is attached to the wiring board 50 so that the light source 20 is located in the through hole 13 of the laminated structure 111 as shown in FIG. An adhesive layer 62 is interposed between the second light-reflecting member 41 of the laminated structure 111 and the coating layer 53 of the wiring board 50. As a result, the structure 400 including the wiring board 50, the laminated structure 111, and the light source 20 is obtained. The adhesive layer 62 may be an adhesive sheet previously bonded to the laminated structure 111. In that case, a laminated structure having a three-layer structure including an adhesive sheet and not having through holes may be prepared to form through holes 13 penetrating these three layers.

There is a gap between the side surface 20a of the light source 20 arranged in the through hole 13 and the inner side surface 13a of the through hole 13. FIG. 14A is a top view of the structure 400 shown in FIG. As shown in FIG. 14A, the upper surface of the coating layer 53 of the wiring board 50 is exposed around the light source 20 in the through hole 13.

After preparing the structure 400, the liquid 31 is supplied to the through hole 13 as shown in FIG. The liquid 31 contains a light diffusing agent, a translucent resin, and a solvent. The liquid 31 is supplied to the through hole 13 by, for example, a dispense method.

The light diffusing agent is, for example, fine particles such as _{TiO 2} , SiO ₂ , Al ₂ O _{3, and ZnO.} The translucent resin is, for example, a liquid thermosetting resin such as epoxy or silicone. The solvent is a liquid of an organic compound. The solvent can be appropriately selected in consideration of the solubility and volatility of the translucent resin. For example, one or two or more selected from hexane, xylene, heptane, acetone, ethanol, isopropyl alcohol, decane, dodecane, tridecane, nonanal, decanal, triethylene glucol and the like can be mixed and used.

A part of the solvent in the liquid 31 evaporates (volatilizes) at room temperature, and then the liquid 31 is heated to evaporate the remaining solvent and cure the translucent resin. As a result, as shown in FIG. 11, the first light reflecting member 31a is formed on the wiring board 50 around the light source 20 in the through hole 13. The first light-reflecting member 31a contains a light diffusing agent and a translucent resin remaining due to evaporation of the solvent in the liquid 31. The cured translucent resin functions as a binder between the light diffusing agents.

The first light reflecting member 31a is formed on the wiring board 50 located between the inner side surface 13a of the through hole 13 and the side surface 20a of the light source 20 in a plan view. That is, the surface of the coating layer 53 of the wiring board 50 exposed in the through hole 13 in the plan view of FIG. 14A is covered with the first light reflecting member 31a formed in a film shape. In the plan view of FIG. 14B, the first light reflecting member 31a in the through hole 13 is represented by hatching.

When the fluidity is low in the state of only the light diffusing agent and the translucent resin, and it is difficult to form a thin and uniform film-like light reflecting member on the surface of the wiring board 50 exposed in the through hole 13. There is. In the present embodiment, the liquid 31 obtained by diluting the light diffusing agent and the translucent resin with a solvent is supplied to the through holes 13, and then the solvent is evaporated. As a result, the entire surface of the wiring board 50 in the through hole 13 can be uniformly covered with the first light-reflecting member 31a which is thin and has a high light diffusing agent concentration (that is, high reflectance). For example, it is preferable to dilute the light diffusing agent and the translucent resin 1.5 to 3 times with a solvent.

By suppressing the thickness of the first light-reflecting member 31a, it is possible to make it difficult for the first light-reflecting member 31a to cover the side surface of the first light-transmitting member 22. Further, when the solvent evaporates, the light diffusing agent tends to be deposited downward due to gravity, and is unlikely to be deposited on the side surface of the first translucent member 22. Therefore, it is difficult for the light-reflecting member to be formed in a film shape on the side surface of the first translucent member 22 at a high concentration, and a sufficient amount of light can be emitted from the side surface of the first translucent member 22.

The liquid 31 can also enter the gap between the lower surface of the light source 20 and the wiring board 50. Depending on the concentration of the light diffusing agent in the liquid 31 that has entered the gap, at least one of the upper surfaces of the wiring substrate 50 under the light source 20 is the first light reflecting member 31a containing the light diffusing agent remaining after the solvent evaporates. Can cover the part.

Depending on the thickness of the liquid 31 on the upper surface of the light source 20 and the concentration of the light diffusing agent, a fourth light reflecting member 31b containing the light diffusing agent may be formed on the upper surface of the light source 20 after the solvent evaporates. The fourth light reflecting member 31b, together with the first light adjusting member 25 formed on the upper surface of the first translucent member 22, has an extremely high brightness in the region directly above the light source 20 as compared with the brightness in the other regions. It functions as a light adjusting member that suppresses the occurrence.

The difference between the thickness of the liquid 31 on the region where the first light-reflecting member 31a is formed and the thickness of the liquid 31 on the region where the fourth light-reflecting member 31b is formed in the through hole 13 is light diffusion. Corresponds to the difference in the amount of agent. The thickness of the liquid 31 on the region where the fourth light-reflecting member 31b is formed is thinner than the thickness of the liquid 31 on the region where the first light-reflecting member 31a is formed, and the thickness of the liquid 31 is smaller than the thickness of the liquid 31 on the region where the first light-reflecting member 31a is formed. The amount of the light diffusing agent in the liquid 31 on the region where the first light reflecting member 31a is formed is smaller than the amount of the light diffusing agent in the liquid 31 on the region where the first light reflecting member 31a is formed. Therefore, the thickness of the fourth light-reflecting member 31b is smaller than the thickness of the first light-reflecting member 31a.

After forming the light-reflecting members 31a and 31b, the second light-transmitting member 70 is arranged in the space inside the through hole 13 as shown in FIG. The second translucent member 70 is formed on the light-reflecting members 31a and 31b and covers the light-reflecting members 31a and 31b. The second translucent member 70 covers the inner side surface 13a of the through hole 13 and the side surface 20a of the light source 20.

After forming the second translucent member 70, a partition groove 14 is formed in the light guide plate 10 as shown in FIG. For example, a partition groove 14 is formed by using a rotary blade such as a dicing saw or a cutter such as a Thomson blade.

As shown in FIG. 2, a step of forming the third light reflecting member 42 in the partition groove 14 may be provided. Further, a step of forming the second light adjusting member 80 on the second light transmissive member 70 may be provided. The third light reflecting member 42 and the second light adjusting member 80 can be formed of the same material at the same time. The third light reflective member 42 and the second light adjusting member 80 can be formed by, for example, printing or inkjet.

FIG. 3B is a schematic cross-sectional view of another example of the light source.

The covering member 124 covers the element side surface 21c and the element lower surface 21b of the semiconductor laminate of the light emitting element 21. The covering member 124 has reflectivity to the light emitted by the light source 20. The covering member 124 can be used, for example, with the same material as the covering member 24 used in the light source 20 shown in FIG. 3A.

The first translucent member 22 is arranged on the element upper surface 21a of the semiconductor laminate of the light emitting element 21. The first translucent member 22 is also arranged on the covering member 124 that covers the element side surface 21c of the light emitting element 21.

FIG. 15 is a schematic cross-sectional view of a portion of the planar light source of another embodiment in which the light source 20 is arranged.

The light source 20 includes a first translucent member 122 that covers the element upper surface 21a and the element side surface 21c of the semiconductor laminate of the light emitting element 21. The first translucent member 122 is a translucent resin member having translucency with respect to the light emitted by the light emitting element 21, and does not substantially contain a phosphor. A phosphor is contained in the second translucent member 170 which is arranged in the through hole 13 and covers the light source 20 and the light reflecting members 31a and 31b. The second translucent member 170 has a translucent resin having translucency with respect to the light emitted by the light emitting element 21, and a phosphor dispersedly contained in the translucent resin.

In the example shown in FIG. 15, the third translucent member 171 is arranged on the second translucent member 170 in the through hole 13. The third translucent member 171 is a translucent resin member having translucency with respect to the light emitted by the light emitting element 21. The second light adjusting member 80 is arranged on the third light transmissive member 171. The third translucent member 171 may or may not contain a fluorescent substance substantially. In the through hole 13, only the second translucent member 170 may be arranged between the light source 20 and the second light adjusting member 80.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. All embodiments that can be implemented by those skilled in the art with appropriate design changes based on the above-described embodiments of the present invention also belong to the scope of the present invention as long as the gist of the present invention is included. In addition, within the scope of the idea of the present invention, those skilled in the art can come up with various modified examples and modified examples, and it is understood that these modified examples and modified examples also belong to the scope of the present invention. ..

1 ... light emitting region, 10 ... light guide plate, 11 ... first main surface, 12 ... second main surface, 13 ... through hole, 20 ... light source, 21 ... light emitting element, 22 ... first translucent member, 23 ... electrode , 24 ... Covering member, 25 ... First light adjusting member, 31 ... Liquid, 31a ... First light reflecting member, 31b ... Fourth light reflecting member, 41 ... Second light reflecting member, 42 ... Third light Reflective member, 50 ... Wiring substrate, 70 ... Second translucent member, 80 ... Second light adjustment member, 100 ... Planar light source, 111 ... Laminated structure

Light absorption near the light source can be reduced.

By arranging the first light-reflecting member 31a having a high diffuse reflectance in the vicinity of the light source 20, it is possible to reduce the light absorption in the vicinity of the light source 20. As a result, the light emitted to the outside from the vicinity of the light source 20 can be brightened. Further, by arranging the second light reflecting portion 41 having a high specular reflectance at a position away from the light source 20, the light emitted to the outside from between the light sources 20 can be brightened. Diffuse reflectance and specular reflectance can be measured by, for example, a high-speed spectrocolorimeter (CMS-35SP) manufactured by Murakami Color Technology Laboratory.

Claims (7)

Wiring board and
A light guide plate arranged on the wiring board, a first main surface, a second main surface opposite to the first main surface and arranged to face the wiring board, and the first main surface. A light guide plate including a first hole portion penetrating from the main surface to the second main surface, and
A light source arranged on the wiring board located in the first hole, and
A first light-reflecting member arranged on the wiring board located between the inner side surface of the first hole portion and the side surface of the light source in a plan view.
A second light-reflecting member arranged on the second main surface side of the light guide plate, and
With
A planar light source in which the diffuse reflectance of the first light-reflecting member with respect to the light emitted by the light source is higher than the diffuse reflectance of the second light-reflecting member with respect to the light emitted by the light source. The planar light source according to claim 1, wherein the first light-reflecting member is a resin member containing a light diffusing agent, and the second light-reflecting member is a resin member containing air bubbles. The light source has a light emitting element and a translucent member that covers the upper surface and the side surface of the light emitting element.
The planar light source according to claim 1 or 2, wherein at least a part of the side surface of the translucent member is exposed from the first light reflecting member. The planar light source according to any one of claims 1 to 3, wherein the translucent member includes a phosphor. A wiring board, a light source plate arranged on the wiring board, a first main surface, and a second main surface on the opposite side of the first main surface and facing the wiring board. A structure including a light guide plate including a first hole portion penetrating from the first main surface to the second main surface, and a light source arranged on the wiring board located in the first hole portion. The process of preparation and
A step of supplying a liquid containing a light diffusing agent, a translucent resin, and a solvent to the first pore portion,
Light reflectivity containing the light diffusing agent and the translucent resin on the wiring substrate located between the inner side surface of the first hole portion and the side surface of the light source in a plan view by evaporating the solvent. The process of forming members and
A method for manufacturing a planar light source. The method for manufacturing a planar light source according to claim 5, wherein the light reflecting member is also formed between the lower surface of the light source and the upper surface of the wiring board. The method for manufacturing a planar light source according to claim 5 or 6, further comprising a step of filling the space in the first hole with a light-transmitting member after forming the light-reflecting member.

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