JP7208548B2 - Planar light source and method for manufacturing planar light source - Google Patents

Description

The present disclosure relates to a planar light source and a manufacturing method of the planar light source.

2. Description of the Related Art As a backlight for a liquid crystal display device, for example, Japanese Unexamined Patent Application Publication No. 2002-100001 discloses a direct type planar light source that includes a light guide member and a plurality of light sources that are two-dimensionally arranged.

JP 2008-59786 A

An object of the present disclosure is to provide a planar light source having a structure in which at least one of color tone and brightness of the light source can be adjusted during manufacturing, and a manufacturing method thereof.

A planar light source according to an embodiment of the present disclosure includes a first principal surface, a second principal surface located on the opposite side of the first principal surface, and a plurality of unit regions arranged one-dimensionally or two-dimensionally. and a plurality of through holes opened in the first main surface and the second main surface and positioned in the plurality of unit regions respectively; and arranged in the plurality of through holes of the light guide plate a plurality of light sources, wherein at least one of the plurality of light sources is arranged in the through hole corresponding to one of the plurality of unit regions; and a second main surface of the light guide plate. a wiring board positioned on the side and on which the plurality of light sources are arranged; and a second translucent member arranged in the through-hole covering at least the upper surface of the first translucent member in each of the plurality of unit regions.

According to the embodiments of the present disclosure, it is possible to obtain a planar light source with a structure that allows at least one of color tone and brightness of the light source to be adjusted during manufacturing.

FIG. 1 is a schematic perspective view showing one embodiment of a planar light source. 2 is a schematic top view of the planar light source shown in FIG. 1. FIG. 3A is a schematic cross-sectional view of one light-emitting unit in the planar light source shown in FIG. 1, taken along line IIIA-IIIA in FIG. 2. FIG. 3B is a schematic cross-sectional view of another light-emitting unit in the planar light source shown in FIG. 1, taken along line IIIB-IIIB in FIG. 2. FIG. 4 is a schematic cross-sectional view of a light source used in the planar light source shown in FIG. 1. FIG. 5A is a schematic cross-sectional view of a main part of one light emitting unit in the planar light source shown in FIG. 1. FIG. 5B is a schematic cross-sectional view of a main part of another form of one light emitting unit in the planar light source shown in FIG. 1. FIG. FIG. 6 is a flow chart showing an embodiment of a method for manufacturing a planar light source. 7A is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 6. FIG. 7B is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 6. FIG. 7C is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 6. FIG. FIG. 7D is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 7E is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 6. FIG. FIG. 7F is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. FIG. 7G is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 7H is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. 6. FIG. FIG. 7I is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. FIG. 7J is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. FIG. 7K is a schematic cross-sectional view showing a method of manufacturing the planar light source 301 shown in FIG. FIG. 8 is a schematic top view of a light guide plate used in the manufacturing method of the planar light source 301 shown in FIG. FIG. 9 is a schematic top view showing the position of the light emitting unit in which the phosphor is added to the second translucent member in the manufacturing method of the planar light source 301 shown in FIG. FIG. 10 is a schematic cross-sectional view showing a main part of another form of the planar light source. FIG. 11A is a schematic cross-sectional view showing another form example of a through hole of a light guide plate. FIG. 11B is a schematic cross-sectional view showing another form example of the through hole of the light guide plate. FIG. 11C is a schematic cross-sectional view showing another form example of the through hole of the light guide plate. FIG. 11D is a schematic cross-sectional view showing another form example of the through hole of the light guide plate.

Embodiments of the present disclosure will be described in detail with reference to the drawings. The following embodiments are examples, and the planar light source and the method for manufacturing a planar light source according to the present disclosure are not limited to the following embodiments. For example, numerical values, shapes, materials, steps, order of steps, and the like shown in the following embodiments are merely examples, and various modifications are possible as long as there is no technical contradiction. Each embodiment described below is merely an example, and various combinations are possible as long as there is no technical contradiction.

The dimensions, shapes, etc. of components shown in the drawings may be exaggerated for clarity, and may not reflect the dimensions, shapes, and size relationships between components in an actual planar light source. Also, in order to avoid making the drawing overly complicated, illustration of some elements may be omitted, or an end view showing only a cut surface may be used as a cross-sectional view.

In the following description, constituent elements having substantially the same functions are denoted by common reference numerals, and their description may be omitted. Also, terms that indicate a particular direction or position (eg, "upper", "lower", "right", "left", and other terms that include those terms) may be used. However, these terms are used only for clarity of relative orientation or position in the referenced drawings. If the relative direction or positional relationship of terms such as “upper” and “lower” in the referenced drawings is the same, drawings other than the present disclosure, actual products, manufacturing equipment, etc. are the same as the referenced drawings. It does not have to be placement. In the present disclosure, “parallel” includes cases where two straight lines, sides, planes, etc. are in the range of about 0° to ±5°, unless otherwise specified. In the present disclosure, "perpendicular" or "perpendicular" includes cases where two straight lines, sides, planes, etc. are in the range of about 90° to ±5° unless otherwise specified. Furthermore, the positional relationship expressed as "above" includes the case of being in contact and the case of not being in contact but being positioned above.

(Structure of planar light source 301)
FIG. 1 is a schematic perspective view of a planar light source 301 of this embodiment, and FIG. 2 is a schematic top view of the planar light source 301. As shown in FIG. A planar light source 301 includes a light emitting module 101 and a wiring board 201 . An insulating layer 80 that protects the wiring substrate 201 of the planar light source 301 may be further provided.

The light emitting module 101 includes a plurality of light emitting units U arranged one-dimensionally or two-dimensionally. In this embodiment, as shown in FIG. 2, the plurality of light emitting units U are arranged two-dimensionally in the x and y directions. In the example shown in FIG. 1 and the like, the light emitting module 101 includes 25 light emitting units U arranged in 5 rows and 5 columns in the x direction and the y direction. However, the number of light-emitting units U included in the light-emitting module 101 is arbitrary and may be another number. One light emitting unit U has, for example, a square or rectangular shape with a side of 1 mm to 20 mm, preferably a side of 4 mm to 10 mm. The light emitting module 101 may correspond to the screen size of the display device used, or may correspond to the screen size of the display device by arranging a plurality of light emitting modules 101 .

3A and 3B are schematic cross-sectional views of one light emitting unit U of the planar light source 301 taken along lines IIIA-IIIA and IIIB-IIIB in FIG. FIG. 5A is a schematic cross-sectional view of a main part of FIG. 3A.

Each light emitting unit U includes a light source 20 , and light emitted from the light source 20 is emitted from the upper surface 101 a of the light emitting module 101 . A wiring board 201 is arranged on the lower surface 101 b of the light emitting module 101 , and the light source 20 of each light emitting unit U is electrically connected to the wiring board 201 . By supplying electric power to the wiring board 201 from the outside, it is possible to simultaneously turn on the plurality of light sources 20 or to selectively turn on some of the light sources 20 . As shown in FIG. 3A, at least one of the plurality of light emitting units U may be doped with a phosphor 35 . By adding the phosphor 35, it is possible to adjust the color tone of the light emitted from each light emitting unit U during manufacturing. FIG. 3B shows a cross-section of the light-emitting unit U that does not contain the phosphor 35. FIG.

As shown in FIGS. 3A and 3B, the light emitting module 101 of the planar light source 301 includes a light guide plate 10, a plurality of light sources 20, a first translucent member 31, and a second translucent member 32. . Further, as detailed below, the light emitting module 101 of the planar light source 301 may further include a light reflecting member 41, a light shielding member 42, a light reflecting sheet 43, and a phosphor 35. . Hereinafter, the structure of the planar light source 301 will be described in more detail by dividing into each component.

[Light guide plate 10]
The light guide plate 10 causes the light emitted from the light source 20 of each light emitting unit U to propagate at least within each light emitting unit U and emit from the upper surface 101 a of the light emitting module 101 . The light guide plate 10 includes a first main surface 10a, a second main surface 10b located on the opposite side of the first main surface 10a, a plurality of unit regions 10U arranged one-dimensionally or two-dimensionally, and a first main surface 10U. and a plurality of through holes 11 that open to the surface 10a and the second main surface 10b and are located in the plurality of unit regions 10U. The first major surface 10a is also the top surface 101a of the light emitting module 101 . A unit area 10U is a unit area of the light guide plate 10 included in one light emitting unit U. As shown in FIG. In this embodiment, in the light guide plate 10, the unit regions 10U are arranged in 5 rows and 5 columns. When viewed from above, the unit region 10U has, for example, a rectangular shape, and as shown in FIG. 2, two sets of sides of the rectangle are parallel to the x direction and the y direction.

The through-hole 11 has openings in the first principal surface 10a and the second principal surface 10b, and is positioned at the center of each unit region 10U on the xy plane as shown in FIG. Furthermore, in plan view, the center of the through-hole 11 preferably coincides with the center of each unit region 10U. In this embodiment, the through hole 11 has a cylindrical shape and has circular openings on the first main surface 10a and the second main surface 10b. At this time, the width (diameter) of the through-hole 11 is sufficient as long as at least the light source 20 can be arranged in the through-hole 11. For example, it is preferably 1.5 mm to 15 mm, more preferably 2 mm to 6 mm. . The distance between the through holes 11 arranged in each adjacent unit region 10U is preferably the same as one side of the light emitting unit U, for example, preferably 1 mm to 20 mm, more preferably 4 mm to 10 mm. .

Moreover, the opening of the through-hole 11 is not limited to a circle, and may have an elliptical shape or a polygonal shape. Also, the size of the opening in the first main surface 10a and the opening in the second main surface 10b may be different. For example, the through-hole 11 has a truncated cone shape in which the opening of the second main surface 10b is larger than the opening of the first main surface 10a, or the opening of the second main surface 10b is smaller than the opening of the first main surface 10a. You may have Moreover, the through-hole 11 may have a shape in which a cylindrical shape and a truncated cone shape are combined, or a shape in which two truncated cone shapes are combined. 11A to 11D show other shape examples of the through hole 11. FIG. 11A is an example of a through hole 11 having a shape in which a cylinder is connected to the bottom surface of a truncated cone, FIG. 11B is an example of a through hole 11 having a shape in which a cylinder is connected to the top surface of a truncated cone, and FIG. An example of a through-hole 11 having a shape in which two truncated cones are connected at the bottom surface, and FIG. 11D respectively show an example of a through-hole 11 having a shape in which two truncated cones are connected at the top surface. The shape of a combination of a truncated cone and a cylinder is not limited to the examples shown in FIGS. 11A and 11B, and each shape may be inverted upside down and formed on the light guide plate 10 .

As will be described later, when each light emitting unit U is partitioned by the light reflecting member 41, the light guide plate 10 may include partitioning grooves 12 in which the light reflecting member 41 is arranged. The dividing grooves 12, for example, have openings in the first main surface 10a and extend along the x-direction or the y-direction on the boundaries between adjacent unit regions 10U. The width of such partition grooves 12 can be set to about 10% or less of the width of one light emitting unit U, for example. More specifically, the width of the dividing grooves 12 is preferably 0.03 mm to 1 mm, more preferably 0.05 mm to 0.8 mm. In this embodiment, the dividing grooves 12 reach the light reflecting sheet 43, and the light guide plate 10 is divided into unit regions 10U. However, the bottom of the dividing groove 12 may not reach the second main surface 10b, and the light guide plate 10 may be partially connected. When viewed from above, the dividing grooves 12 are arranged on the outer periphery of each unit region 10U, and each unit region 10U is a region surrounded by the dividing grooves 12. As shown in FIG.

In addition, the upper surface of the light guide plate 10 may have a convex portion and/or a concave portion, for example, in a low luminance area in order to reduce luminance unevenness.

The light guide plate 10 is made of a translucent material such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, thermoplastic resin such as polyethylene terephthalate resin or polyester resin, thermosetting resin such as epoxy resin or silicone resin, or Materials such as glass can be used. The thickness of the light guide plate 10 is, for example, 200 μm or more and 800 μm or less.

[Light source 20]
Each of the plurality of light sources 20 is arranged in the through hole 11 of the light guide plate 10 corresponding to one of the plurality of unit regions 10U. Although one light source 20 is arranged in one through hole 11 in this embodiment, two or more light sources 20 may be arranged in the through hole 11 . The light source 20 has an upper surface 20a, a lower surface 20b and side surfaces 20c. The shape of the light source 20 when viewed from above is, for example, a rectangle, and has four side surfaces 20c. As shown in FIG. 2, for example, in top view, each side of the rectangle of the light source 20 is non-parallel to each side of the rectangle of the unit region 10U. In the example of FIG. 2, since the light source 20 and the unit area 10U have a square shape when viewed from above, each side of the rectangle of the light source 20 is +45 degrees or 135 degrees with respect to each side of the unit area 10U ( −45 degrees). According to such an arrangement, since the four side surfaces of the light source 20 face the four corners of the unit region when viewed from the top, the brightness near the four corners farthest from the center of the unit region 10U is reduced. Decrease can be suppressed.

FIG. 4 is a cross-sectional view of the light source 20. As shown in FIG. The light source 20 may be a single light-emitting element, or may have a structure in which an optical member such as a wavelength conversion member is combined with a light-emitting element. In this embodiment, the light source 20 includes a light emitting element 21, a translucent member 22, a light adjusting member 23, a covering member 24, and an electrode 25, as shown in FIG. Moreover, the electrode 25 can be omitted as appropriate when the p-side electrode and the n-side electrode of the light emitting element 21 to be described later are used as the electrodes of the light source 20 .

A typical example of the light emitting element 21 is an LED. The light emitting element 21 includes, for example, a support substrate such as sapphire or gallium nitride, and a semiconductor laminate on the support substrate. The semiconductor laminate includes an n-type semiconductor layer, a p-type semiconductor layer, a light-emitting layer sandwiched therebetween, and a p-side electrode and an n-side electrode electrically connected to the n-type semiconductor layer and the p-type semiconductor layer. . The semiconductor laminate may contain a nitride semiconductor (In _x Al _y Ga _1-xy N, 0≦x, 0≦y, x+y≦1) capable of emitting light in the ultraviolet to visible region.

The light emitting layer may have a structure such as a double heterojunction or a single quantum well (SQW), or may have a structure with a group of light emitting layers such as a multiple quantum well (MQW). good. Further, the semiconductor laminate may have a structure including one or more light emitting layers between the n-type semiconductor layer and the p-type semiconductor layer, or the n-type semiconductor layer, the light emitting layer and the p-type semiconductor layer. You may have a structure in which a structure containing and in order is repeated multiple times. When the semiconductor laminate includes a plurality of light-emitting layers, it may include light-emitting layers with different emission peak wavelengths, or may include light-emitting layers with the same emission peak wavelength. In addition, the same emission peak wavelength includes the case where there is a variation of about several nanometers. When the semiconductor stack comprises two light-emitting layers, for example, blue light and blue light, green light and green light, red light and red light, ultraviolet light and ultraviolet light, blue light and green light, blue light and red light, Alternatively, the light-emitting layer can be selected with a combination of green light and red light. Each light-emitting layer may include a plurality of active layers with different emission peak wavelengths, or may include a plurality of active layers with the same emission peak wavelength.

The light emitting element 21 may be a light emitting element that emits blue light, or may be a light emitting element that emits a color other than blue light, such as red light or green light. Further, one light emitting unit U may include a light emitting element that emits red light, a light emitting element that emits blue light, and a light emitting element that emits green light. In this embodiment, as the light emitting element 21 of each light emitting unit U, an LED that emits blue light is exemplified.

The top view shape of the light emitting element 21 is typically rectangular. The length of one side of the rectangular shape of the light emitting element 21 is, for example, 1000 μm or less. The vertical and horizontal dimensions of the rectangular shape of the light emitting element 21 may be 500 μm or less. A light-emitting element with vertical and horizontal dimensions of 500 μm or less can be easily procured at low cost. Alternatively, the vertical and horizontal dimensions of the rectangular shape of the light emitting element 21 may be 200 μm or less. If the length of one side of the rectangular shape of the light emitting element 21 is short, it is advantageous for expression of high-definition images, local dimming operation, etc. in application to a backlight unit of a liquid crystal display device. In particular, a light-emitting element having both vertical and horizontal dimensions of 250 μm or less has a small upper surface area, so that the amount of light emitted from the side surfaces of the light-emitting element is relatively large. Therefore, it is easy to obtain a batwing type light distribution characteristic. Here, in a broad sense, the batwing type light distribution characteristic means light emission with high emission intensity at an angle where the absolute value of the light distribution angle is larger than 0°, with the optical axis perpendicular to the upper surface of the light emitting element being 0°. It refers to the light distribution characteristics as defined by the intensity distribution.

The light emitting element 21 includes an emission surface 21a, an electrode surface 21b, and side surfaces 21c. A pair of electrodes 25 electrically connected to the p-side electrode and the n-side electrode are positioned on the electrode surface 21b.

Translucent member 22 is arranged to cover emission surface 21 a and side surface 21 c of light emitting element 21 . The translucent member 22 protects the light emitting element 21 and has functions such as wavelength conversion and light diffusion according to the particles added to the translucent member 22 . Specifically, the translucent member 22 contains a translucent resin and may further contain a phosphor. When phosphor is included, the translucent member 22 is also a wavelength converting member. Examples of phosphors include yttrium-aluminum-garnet-based phosphors (eg, Y ₃ (Al, Ga) ₅ O ₁₂ :Ce), lutetium-aluminum-garnet-based phosphors (eg, Lu ₃ (Al, Ga) ₅ O ₁₂ :Ce), terbium-aluminum-garnet-based phosphors (e.g., _{Tb3 (} Al, Ga) _5O12 :Ce), CCA _- based phosphors (e.g., _{Ca10 (} PO4) _6C12 :Eu), SAE phosphors (eg, Sr ₄ Al ₁₄ O ₂₅ :Eu), chlorosilicate phosphors (eg, Ca ₈ MgSi ₄ O _{16 Cl 2} :Eu), β-sialon phosphors (eg, (Si, Al) ₃ (O, N) ₄ :Eu), α-sialon-based phosphors (for example, M _z (Si, Al) ₁₂ (O, N) ₁₆ :Eu (where 0<z≦2, M is Li, Mg, Ca, Y, and lanthanide elements excluding La and Ce)), SLA phosphors (eg SrLiAl ₃ N ₄ :Eu), CASN phosphors (eg CaAlSiN ₃ :Eu) or SCASN phosphors ( For example, nitride-based phosphors such as (Sr, Ca)AlSiN ₃ :Eu), KSF-based phosphors (eg, K ₂ SiF ₆ :Mn), KSAF-based phosphors (eg, K ₂ (Si, Al) F ₆ :Mn) or fluoride-based phosphors such as MGF-based phosphors (e.g., _{3.5MgO.0.5MgF2.GeO2} :Mn), phosphors having a perovskite structure (e.g., CsPb (F, Cl, Br, I) ₃ ), or quantum dot phosphors (eg, CdSe, InP, AgInS ₂ or AgInSe ₂ ), or the like can be used.

The translucent member 22 may contain a plurality of types of phosphors, for example, a phosphor that absorbs blue light and emits yellow light, and a phosphor that absorbs blue light and emits red light. may contain a phosphor that Thereby, for example, white light can be emitted from the light source 30 . Further, the translucent member 22 may contain a light diffusing material to the extent that it does not block light. The content of the light diffusing material contained in the translucent member 22 is such that the transmittance of the translucent member 22 with respect to the light emitted from the light emitting element 21 is 50% or more and 99% or less, preferably 70% or more and 90% or less. can be adjusted to be As the light diffusing material, for example, titanium oxide, silica, alumina, zinc oxide, glass, or the like can be used.

The covering member 24 is arranged on the electrode surface 21 b excluding the electrode 25 electrically connected to the light emitting element 21 and further covers the lower surface of the translucent member 22 . The coating member 24 has a light reflectivity, and reflects the light emitted from the light emitting layer of the light emitting element 21 and then the light directed toward the electrode surface 21b toward the emission surface 21a. The covering member 24 is made of, for example, a resin material containing a light diffusing material. Specifically, the covering member 24 is silicone resin or epoxy resin containing a light diffusing material made of particles such as titanium oxide, silica, alumina, zinc oxide, or glass. Also, the covering member 24 may be an inorganic member.

The light adjusting member 23 is positioned on the upper surface 22 a of the translucent member 22 and controls the amount and direction of light emitted from the upper surface 22 a of the translucent member 22 . The light adjusting member 23 can be made of, for example, a translucent resin material, a metal thin film, or an inorganic member in which the above-described light diffusing material is dispersed. Part of the light emitted from the upper surface 22 a of the translucent member 22 is reflected by the light diffusing material, metal thin film, or the like of the light adjusting member 23 , and the other part passes through the light adjusting member 23 . The transmittance of the light adjustment member 23 is, for example, preferably 1% or more and 50% or less, and more preferably 3% or more and 30% or less. As a result, the luminance directly above the light source 20 is reduced, and the in-plane variation in the luminance of the planar light source 301 is reduced.

[First translucent member 31]
As shown in FIG. 5A, the first translucent member 31 is arranged in the through hole 11 so as to cover at least part of the side surface of the light source 20 in each of the plurality of unit regions 10U of the light guide plate 10. there is More specifically, the first translucent member 31 is positioned on the second main surface 10b side within the through hole 11 , is in contact with a translucent adhesive sheet 51 described later, and defines the through hole 11 . It is in contact with the side surface 11 c and the side surface 20 c of the light source 20 . The first translucent member 31 may be in contact with part or all of the side surface 11c that defines the through hole 11 . This allows the light emitted from the side surface 20 c of the light source 20 to enter the light guide plate 10 efficiently. The first translucent member 31 can cover at least one of the four sides 20c of the light source 20, and covers the four sides 20c of the light source 20 in this embodiment. Moreover, it is preferable that the first translucent member 31 is in contact with the translucent member 22 forming part of the side surface 20 c of the light source 20 . In order for the light from the light source 20 to enter the light guide plate 10 more efficiently, the refractive index of the first translucent member 31 is adjusted to that of the member forming the side surface 20c of the light source 20 (translucent member 22) is preferably larger than the refractive index. Also, the refractive index of the first translucent member 31 is preferably smaller than the refractive index of the light guide plate 10 .

Further, when manufacturing the planar light source 301 , the light source 20 is arranged in the through hole 11 of the light guide plate 10 and filled with the first translucent member 31 to fix the light source 20 and attach each light source to the wiring substrate 201 . 20 can be electrically connected. Therefore, the light source 20 is turned on in this state, and the lighting inspection of the light source 20 is performed, such as checking the color of the light emitted from the light source 20, the spread in the light guide plate 10, and the balance of the color tone of the entire planar light source. becomes possible.

When the planar light source 301 includes the light shielding member 42, the first translucent member 31 preferably does not cover the upper surface 20a of the light source 20 and is not positioned on the upper surface 20a. Since the first translucent member 31 does not cover the upper surface 20a of the light source 20, the light incident on the first translucent member 31 from the side surface 20c of the light source 20 is directed toward the upper surface 20a of the light source 20 during the lighting inspection. is suppressed. Therefore, even if the lighting inspection is performed before forming the light shielding member 42, the light distribution equivalent to that when the light shielding member 42 is formed, in other words, the light distribution closer to the light distribution of the completed planar light source 301 can be obtained. It can be realized by lighting inspection. Therefore, as will be described later, based on the results of the lighting inspection, when adding a phosphor or a light diffusion member to the second translucent member 32 to adjust the color tone and light distribution, the color tone can be adjusted more accurately. , it becomes possible to more easily determine the amount of the phosphor and the light diffusion material.

In the lighting inspection, as long as a light distribution close to that of the completed planar light source 301 is obtained, the first translucent member 31 covers part of the upper surface 20a of the light source 20 in some or all of the plurality of unit regions 10U. may be covered. Further, if the first translucent member 31 covering the upper surface 20a of the light source 20 is sufficiently thin, the first translucent member 31 covers the upper surface 20a of the light source 20 in some or all of the plurality of unit regions 10U. It may cover the whole.

Moreover, it is preferable that the upper surface 31a of the first translucent member 31 has a recess 31d that is recessed toward the second main surface 10b of the light guide plate 10 . As a result, the light from the light source 20 can be diffused by the curved upper surface 31a of the first translucent member 31, and the luminance near the light source 20 can be prevented from becoming too high.

As described above, in the through hole 11 in which the first translucent member 31 is arranged, at least a space for arranging the second translucent member 32 is left. Therefore, based on the results of the lighting inspection, the second translucent member 32 added with a phosphor or light diffusing material is placed inside the through hole 11 and above the upper surface 20 a of the light source 20 and the first translucent member 31 . , the color and distribution of the light emitted from the light source 20 can be adjusted for each light emitting unit U. As described above, since the upper surface 20a of the first translucent member 31 has the concave portion 31d, the phosphor or the light diffusing material added to the second translucent member 32 depending on the position and size of the concave portion 31d can be used. It is possible to adjust the position and amount of , and it is possible to widen the range of adjustment of the color and distribution of the light emitted from the light source 20 . For example, the concave portion 31d in the present embodiment is positioned lower than the upper surface 20a of the light source 20 so that the phosphor or light diffusing material added to the second translucent member 32 is arranged near the side surface 20C of the light source 20. It is recessed on the second main surface side of the light guide plate 10 . This makes it easier for the light emitted from the light source 20 to irradiate the phosphor and the light diffusing material arranged in the second translucent member 32 .

More preferably, the first translucent member 31 covers as much area of the side surface 20c of the light source 20 as possible. Specifically, the first translucent member 31 preferably covers 60% or more of each side surface 20c of the light source 20, and more preferably covers 80% or more. As a result, the light emitted from the side surface 20c of the light source 20 can enter the light guide plate 10 more efficiently during the lighting inspection, and the spread of light on the light guide plate 10 can be evaluated more accurately. In the example shown in FIG. 5B , the first translucent member 31 covers the entire covering member 24 exposed on the side surface 20 c of the light source 20 and the entire translucent member 22 . The first translucent member 31 may further cover the light adjusting member 23 .

As shown in FIGS. 5A and 5B, the position of the outer edge of upper surface 31a of first translucent member 31 in contact with light guide plate 10 and the position of the inner edge in contact with side surface 20c of light source 20 can be set arbitrarily. In particular, the outer edge of the upper surface 31 a of the first translucent member 31 is preferably set at a position higher than the inner edge, so that the light from the light source 20 can be easily incident on the light guide plate 10 .

The first translucent member 31 contains, for example, translucent resin such as silicone resin, epoxy resin, or a resin mixture thereof. In addition, the first translucent member 31 may further contain a light diffusing material made of particles such as titanium oxide, silica, alumina, zinc oxide, or glass.

[Second Translucent Member 32, Phosphor 35]
The second translucent member 32 is arranged in the through hole 11 covering at least the upper surface 31a of the first translucent member 31 in each of the plurality of unit regions 10U of the light guide plate 10 . In this embodiment, the second translucent member 32 is positioned on the upper surface 20 a of the light source 20 and the upper surface 31 a of the first translucent member 31 and is in contact with the side surface 11 c that defines the through hole 11 . The second translucent member 32 does not have to be in contact with the side surface 11c that defines the through hole. When the upper surface 31a of the first translucent member 31 has the recessed portion 31d, the lower surface 32b of the second translucent member 32 is in contact with the upper surface 31a of the first translucent member 31. It has a first projection 32d extending toward the second main surface 10b. Further, when the second translucent member 32 contains a light diffusing material, part of the light emitted from the upper surface 20 a of the light source 20 can also enter the light guide plate 10 .

The position of the upper surface 32a of the second translucent member 32 may be the same as that of the first main surface 10a of the light guide plate 10, or the upper surface 32a may have a concave portion or a convex portion so that the light can be guided. The bottom of the concave portion of the upper surface 32a may be lower than the first main surface 10a of the light plate 10, or the convex portion of the upper surface 32a may be higher than the first main surface 10a.

As with the first translucent member 31, the second translucent member 32 contains, for example, a translucent resin such as silicone resin, epoxy resin, or a resin mixture thereof.

As shown in FIG. 3A, the planar light source 301 may include the phosphor 35, and the phosphor 35 may be arranged inside the second translucent member 32 in at least one of the plurality of unit regions 10U. In this case, within the second translucent member 32, the phosphor 35 may be unevenly distributed on the lower surface 32b side. Here, uneven distribution means that, for example, when the second translucent member 32 is divided into two parts in the height direction, the density of the phosphors 35 in the lower part is higher than the density of the phosphors 35 in the upper part. .

The phosphor 35 is added based on the result of lighting inspection. For example, if it is determined from the result of the lighting inspection that the light emission in a certain unit region lacks a red component, the phosphor 35 that emits red light is added. The phosphor 35 added to the second translucent member 32 may be of one type, or may be of two or more types that emit light of different colors. Also, the amount of the phosphor 35 added may be adjusted based on the result of the lighting inspection. Further, if the result of the lighting inspection shows that it is not necessary to add the phosphor 35, the second translucent member 32 of any unit region 10U may not contain the phosphor 35. FIG. Furthermore, a light diffusing material may be added based on the results of the lighting inspection. For example, when it is determined that the brightness of a certain unit region 10U is low, light diffusing material is added to increase the amount of light extracted from the upper surface 10a of the light guide plate 10 and the upper surface 32a of the second translucent member 32. , and the luminance distribution of the planar light source 301 can be adjusted.

The translucent resin contained in the second translucent member 32 may be the same as or different from the translucent resin contained in the first translucent member 31 . When the second translucent member 32 contains the same kind of translucent resin as the first translucent member 31, the second translucent member 32 and the first translucent member 31 have almost the same refractive index. Therefore, since the refractive index difference at the interface between the upper surface 31a of the first translucent member 31 and the lower surface 32b of the second translucent member 32 is zero or small, reflection at the interface is suppressed, and the first translucent member 31 and the second translucent member 32, the light is efficiently transmitted therethrough.

On the other hand, when it is desired to prevent the brightness in the vicinity of the light source 20 from becoming too high by reflecting the light propagating through the first translucent member 31 on the upper surface 31a of the first translucent member 31, the second The refractive index of the translucent member 32 is preferably smaller than that of the first translucent member 31 .

As described above, the phosphor 35 in the second translucent member 32 can be added during manufacturing based on the color tone of the light emitted from the light source 20 in each unit region 10U. As shown in FIG. 3B, the second translucent member 32 may not contain the phosphor 35 in the unit region 10U where the phosphor 35 does not need to be added.

The second translucent member 32 may further contain a light diffusing material made of particles such as titanium oxide, silica, alumina, zinc oxide, or glass.

[Light Reflective Member 41]
The light reflective member 41 is arranged in the partition groove 12 of the light guide plate 10 . As a result, the light reflecting member 41 is arranged on the outer periphery of each unit region 10U of the light guide plate 10, and each unit region 10U is surrounded by the light reflecting member 41 when viewed from above. The light reflecting member 41 reflects part or all of the light emitted from the light source 20 and incident on the light guide plate 10 . Therefore, the light emitted from the light source 20 is suppressed from entering the adjacent unit region 10U.

For the light reflecting member 41, for example, a resin containing a light diffusing material or a metal can be used. As the resin used for the light reflective material, thermoplastic resin such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin or polyester resin, or thermosetting resin such as epoxy resin or silicone resin can be used. can. Particles of titanium oxide, silica, alumina, zinc oxide, glass, or the like can be used as the light diffusing material. Moreover, as the metal used for the light-reflecting material, for example, platinum (Pt), silver (Ag), rhodium (Rh), or aluminum (Al) can be used. 3A and 3B, the light-reflecting member 41 fills the inside of the dividing groove 12, but for example, the light-reflecting member 41 covers only the inner surface of the dividing groove 12 in a layered manner. A space may be formed in a part of 12 .

The reflectance of the light reflecting member 41 is preferably 20% to 95%, more preferably 50% to 90%, with respect to the light from the light source 20, and is arbitrarily determined according to the specifications required for the planar light source 301. can. For example, when the light-emitting units U of the planar light source 301 are driven by local dimming, if a light-emitting characteristic with a large contrast is required at the boundary between the light-emitting units U that are lit and the light-emitting units U that are not lit. , the reflectance of the light reflecting member 41 is preferably high. On the other hand, when a light emission characteristic in which the luminance gradually changes at the boundary between the light emitting unit U and the light emitting unit U not lit is desired, it is preferable that the reflectance of the light reflecting member 41 is small. .

[Light shielding member 42]
The light shielding member 42 is arranged on at least part of the upper surface 32a of the second translucent member 32 in the through hole 11 of each unit region 10U. The light shielding member 42 reflects a portion of the light emitted from the light source 30 and transmitted through the second translucent member 32 and transmits the other portion. The thickness of such light shielding member 42 is preferably 0.005 mm to 0.2 mm, more preferably 0.01 mm to 0.075 mm. Further, the reflectance of the light shielding member 42 is preferably set lower than the reflectance of the light adjustment member 23 of the light source 20, and is preferably 20% to 90%, more preferably 20% to 90% of the light from the light source 20. is between 30% and 85%. The light shielding member 42 may be made of, for example, a resin material containing a light diffusing material, or may be made of a metal material. For example, as the resin material, a silicone resin, an epoxy resin, or a resin mixture thereof can be used. Particles of titanium oxide, silica, alumina, zinc oxide, glass, or the like can be used as the light diffusing material. Also, the light shielding member 42 may be composed of a dielectric multilayer film. In the present embodiment, the light shielding member 42 is provided in the form of a film, but may be provided in the form of dots.

As shown in FIGS. 2, 3A, and 3B, in the present embodiment, the light blocking member 42 has a rectangular shape when viewed from above. Two sets of sides of the rectangle are parallel to the light reflecting member 41 positioned on the outer circumference of the light emitting unit U. As shown in FIG. The light shielding member 42 is a part of the upper surface 32 a of the second translucent member 32 and preferably covers a region located above the upper surface 20 a of the light source 20 . In the present embodiment, the light shielding member 42 covers the region above the light source 20 and is positioned inside the through hole 11 when viewed from above. A portion of the upper surface 32a of the second translucent member 32 is not covered with the light shielding member 42 and is exposed to the outside. The shape of the light shielding member 42 when viewed from above may be a circle or other shape, is larger than the upper surface 32a of the second translucent member 32, covers the entire upper surface 32a, and has an outer edge portion extending from the light guide plate 10. may be located on the first main surface 10a of the

In addition to the upper surface 32a of the second light-transmitting member 32, the light shielding members 42 are scattered in high-luminance regions of the first main surface 10a of the light guide plate 10 in order to reduce luminance unevenness. good too.

[Light reflective sheet 43]
The light reflective sheet 43 is located between the wiring board 201 and the light guide plate 10 and covers the second main surface 10b of the light guide plate 10 . In this embodiment, in order to adhere the light reflective sheet 43 to the second main surface 10 b of the light guide plate 10 , the light transmissive adhesive sheet 51 is placed between the light reflective sheet 43 and the second main surface 10 b of the light guide plate 10 . placed in between. As shown in FIGS. 3A and 3B, the light reflective sheet 43 is also arranged inside the through hole 11 of the light guide plate 10, and inside the through hole 11, the lower surface 20b of the light source 20 and the first translucent member. 31 also covers the lower surface 31b. As shown in FIGS. 3A and 3B, the dividing grooves 12 provided in the light guide plate 10 may reach the translucent adhesive sheet 51 and the light reflecting sheet 43 .

The light reflective sheet 43 reflects the light that propagates through the light guide plate 10 toward the outside from the second main surface 10b toward the first main surface 10a.

As the light-reflective sheet 43, a resin sheet containing a large number of air bubbles (for example, a foamed resin sheet), a resin sheet containing a light diffusing material, or the like can be used. Examples of resins used for these light-reflecting sheets 43 include thermoplastic resins such as acrylic resins, polycarbonate resins, cyclic polyolefin resins, polyethylene terephthalate resins and polyester resins, and thermosetting resins such as epoxy resins and silicone resins. can be used. Particles of titanium oxide, silica, alumina, zinc oxide, glass, or the like can be used as the light diffusing material.

[Wiring board 201]
The wiring board 201 has a first principal surface 201a and a second principal surface 201b positioned opposite to the first principal surface 201a. there is The wiring board 201 has a wiring pattern for electrically connecting the plurality of light sources 20 therein. is electrically connected to the terminal 61 located at the . The wiring pattern may be located on the first main surface 201 a or the second main surface 201 b of the wiring board 201 .

The wiring substrate 201, the adhesive sheet 52, the light reflective sheet 43, and the translucent adhesive sheet 51 have holes 65 through which parts of the electrodes 25 are exposed, and the wirings 70 are arranged in the holes 65. FIG. One end of the wiring 70 is in contact with the electrode 25 . The other end of the wiring 70 is connected to the terminal 61 on the second main surface 201 b of the wiring board 201 . The wiring board 201 is thereby electrically connected to the plurality of light sources 20 .

[Insulating layer 80]
The insulating layer 80 is provided on the second main surface 201b of the wiring substrate 201 so as to cover the terminals 61 and the wirings 70 located on the second main surface 201b. By covering the second main surface 201b of the wiring board 201, the insulating layer 80 suppresses electrical shorting of the terminals of the second main surface 201b and protects the second main surface 201b from the external environment. do.

(Manufacturing method of planar light source 301)
An embodiment of a method for manufacturing the planar light source 301 will be described. FIG. 6 is a flow chart showing an example of the manufacturing method of the planar light source 301, and FIGS. 7A to 7K are process cross-sectional views in the manufacturing method of the planar light source 301 shown in FIG. Since FIGS. 7A to 7K show the cross section of one light emitting unit U, reference numerals indicating the light emitting unit U are not attached in each figure. The manufacturing method of the planar light source 301 of the present embodiment comprises a step of preparing a wiring board (S1), a step of arranging a light guide plate (S3), and a step of arranging the light source and the first translucent member (S4). and a step (S8) of arranging the second translucent member. The method of manufacturing planar light source 301 further includes a step of placing a light reflective sheet (S2), a step of forming partition grooves (S5), and a step of electrically connecting the light source and the wiring board (S6). Then, a step of performing a lighting inspection of the light source (S7), a step of arranging the light shielding member and the light reflecting member (S9), a step of arranging the insulating layer (S10), and a cutting step of the assembly (S11). may further include

[Step of preparing wiring board (S1)]
As shown in FIG. 7A, a wiring substrate 201 is prepared which has a first main surface 201a and a second main surface 201b opposite to the first main surface 201a. A terminal 61 is arranged on the second main surface 201 b , and a wiring pattern is formed inside the wiring substrate 201 . Wiring patterns may be formed on the first main surface 201a and the second main surface 201b.

[Step of Arranging Light Reflective Sheet (S2)]
A light reflective sheet 43 is arranged on the first main surface 201 a of the wiring board 201 . The adhesive sheet 52 is placed on the first main surface 201 a of the wiring board 201 , and the light reflective sheet 43 is placed on the adhesive sheet 52 to attach the light reflective sheet 43 to the wiring board 201 . A wiring board in which the light reflective sheet 43 is arranged on the first principal surface 201a may be prepared in advance, or a wiring board having a light reflective first principal surface 201a may be prepared. In these cases, this step can be omitted.

[Step of Arranging Light Guide Plate (S3)]
A light guide plate 10 is prepared. FIG. 8 is a plan view of the light guide plate 10. FIG. The light guide plate 10 has a first main surface 10a, a second main surface 10b located opposite to the first main surface 10a, and a plurality of unit regions 10U arranged one-dimensionally or two-dimensionally. Light guide plate 10 also includes a plurality of through-holes 11 that open to first main surface 10a and second main surface 10b and are located in a plurality of unit regions 10U. The plurality of unit regions 10U are arranged, for example, in 5 rows and 5 columns in the x direction and the y direction. In FIG. 8, the dashed lines indicate the positions of the boundaries of the unit regions 10U, but the light guide plate 10 may not be provided with grooves or the like at the positions indicated by the dashed lines.

Also, in FIG. 8, the light guide plate 10 has a size corresponding to the number of the light emitting units U included in the planar light source 301 to be finally manufactured. A light guide plate assembly having more unit areas 10U than the number of unit areas 10U may be prepared. For example, a light guide plate assembly in which four light guide plates 10 are integrated may be used. In this case, the light guide plate assembly includes, for example, unit regions 10U arranged in 10 rows and 10 columns.

As shown in FIG. 7C, the prepared light guide plate 10 is placed on the first main surface 201a side of the wiring board 201 with the translucent adhesive sheet 51 interposed therebetween, and the light guide plate 10 is fixed to the wiring board 201 . In this embodiment, the light-reflecting sheet 43 is arranged on the first main surface 201a of the wiring board 201, so that the light-reflecting sheet 43 is arranged on the second main surface 10b of the light guide plate 10 with the translucent adhesive sheet 51 interposed therebetween. glued to.

Subsequently, as shown in FIG. 7D, holes 65 for forming wirings 70 connecting the light source 20 and the terminals 61 of the wiring board 201 are formed. Specifically, holes 65 are formed in the translucent adhesive sheet 51, the light reflective sheet 43, the adhesive sheet 52, and the wiring substrate 201 by punching, drilling, laser processing, or the like so as to continuously penetrate these members. . Further, by laminating sheets having holes 65 formed therein in advance, the holes 65 may be formed so as to continuously penetrate the sheets.

[Step of Arranging Light Source and First Translucent Member (S4)]
As shown in FIGS. 7E and 7F, the light source 20 and the first translucent member 31 are arranged in each of the through holes 11 of the plurality of unit regions 10U of the light guide plate. Specifically, as shown in FIG. 7E , one of the plurality of light sources 20 is arranged on the first major surface 201 a of the wiring substrate 201 within the through hole 11 of the light guide plate 10 . Since a part of the translucent adhesive sheet 51 is exposed in the through-hole 11 , the light source 20 is in contact with the wiring substrate 201 by the contact between the lower surface 20 b of the light source 20 and the translucent adhesive sheet 51 . Temporarily fixed. The light source 20 is aligned with the through hole 11 so that the electrode 25 of the light source 20 overlaps the hole 65 of the translucent adhesive sheet 51 .

Subsequently, as shown in FIG. 7F, an uncured first translucent member is applied so as to cover the side surface 20c of the light source 20, the side surface of the through hole 11, and the upper surface of the translucent adhesive sheet 51 exposed in the through hole 11. As shown in FIG. 31 ′ is placed in the through hole 11 . After that, the uncured first translucent member 31' is cured. As a result, the uncured first translucent member 31' shrinks, and the cured first translucent member 31 having the concave portion 31d formed in the upper surface 31a is obtained. The position of the upper surface 31a and the depth of the recess 31d can be adjusted by the amount of the uncured first translucent member 31' filled. The heating temperature for curing the uncured first translucent member 31' is preferably 30°C to 150°C, more preferably 40°C to 130°C.

[Step of forming partition grooves (S5)]
As shown in FIG. 7G, dividing grooves 12 are formed in the light guide plate 10 when the light reflecting member 41 that divides the unit area 10U is provided. On the first main surface 10a of the light guide plate 10, division grooves 12 are formed at the boundaries between the plurality of unit regions 10U using, for example, a dicing saw equipped with a rotary blade, a laser processing device, or the like.

[Step of electrically connecting the light source and the wiring board (S6)]
As shown in FIG. 7H, the plurality of light sources 20 and the wiring board 201 are electrically connected. Specifically, for example, the wiring board 201 to which the light guide plate 10 is joined is held with the second main surface 201b facing upward, and a conductive paste is applied, for example, inside the hole 65 and on the second main surface 201b. 70' is arranged, and a wiring pattern is formed to connect the electrode 25 of the light source 20 and the terminal 61 on the second main surface 201b. After that, the wiring 70 is formed by removing the solvent and the like from the conductive paste 70' and hardening it.

Since the position of the light source 20 is fixed by the cured first translucent member 31, the position of the electrode 25 of the light source 20 and the hole 65 may be misaligned when the conductive paste 70' is formed. ' is suppressed from leaking from between the hole 65 and the electrode 25 . Moreover, disconnection of the formed wiring 70 due to movement of the light source 20 is also suppressed.

[Step of inspecting lighting of light source (S7)]
A plurality of light sources 20 are turned on and emitted light is inspected. The wiring board 201 to which the light guide plate 10 is joined is held so that the light guide plate 10 is positioned upward, power is supplied to the wiring board 201 to turn on the light source 20, and the emitted light is inspected. For example, all of the plurality of light sources 20 are turned on at the same time, an image of the light guide plate 10 viewed from above is captured, and the captured image is analyzed to inspect the chromaticity distribution.

At this time, since the first translucent member 31 is arranged in the through hole 11 and is in contact with the light source 20 and the light guide plate 10, the light emitted from the light source 20 passes through the first translucent member 31. It is possible to inspect the light distribution in a state close to the completed planar light source 301 . Even if the first translucent member 31 is not arranged, the light source 20 can be turned on. As a result, the light from the light source 20 is reflected or refracted by the side surface 20c of the light source 20 and the side surface defining the through hole 11 of the light guide plate 10, and the light distribution of the planar light source 301 and the light distribution during the lighting inspection. can vary greatly.

[Step of Arranging Second Translucent Member (S8)]
A second translucent member 32 is arranged in the through hole 11 . As shown in FIG. 7I, in the through holes 11 of the plurality of unit regions U, uncured second translucent members 32' are arranged so as to cover at least the upper surfaces 31a of the first translucent members 31, respectively. At this time, at least one of the phosphor 35 and the light diffusing material may be added to the uncured second translucent member 32' in at least one of the plurality of unit regions based on the result of the lighting inspection described above. . For example, as shown in FIG. 9, among the through holes 11 of the unit region U arranged in 5 rows and 5 columns, in the hatched through holes 11, the uncured second translucent member 32' is coated with the phosphor. 35 is added. The type and amount of phosphor 35 may be determined based on the result of lighting inspection.

After that, the second translucent member 32 is arranged in the through-hole 11 by curing the uncured second translucent member 32 ′. The heating temperature for curing the uncured second translucent member 32' is preferably 30°C to 150°C, more preferably 40°C to 130°C.

[Step of arranging light shielding member and light reflecting member (S9)]
As shown in FIG. 7J, the light reflecting member 41 is arranged on the light guide plate 10 and the light shielding member 42 is arranged on the second translucent member 32 . An uncured light-reflecting member 41 ′ is arranged in the dividing groove 12 of the light guide plate 10 . Similarly, an uncured light blocking member 42 ′ is arranged so as to cover the upper surface 32 a of the second translucent member 32 . After that, by curing the uncured light-reflecting member 41 ′ and the uncured light-shielding member 42 ′, the light-reflecting member 41 is arranged in the partition groove 12 of the light guide plate 10 , and the second light-transmitting member 32 A light shielding member 42 is arranged on the upper surface 32a of the .

[Step of arranging an insulating layer (S10)]
As shown in FIG. 7K, an insulating layer 80 is formed on the second main surface 201b of the wiring board 201 so as to cover the terminals 61 and the wirings . Thereby, the planar light source 301 is completed.

[Aggregate cutting step (S11)]
When the light guide plate 10 forms an assembly, a structure in which a plurality of planar light sources 301 are connected is obtained by the above process. Therefore, the obtained structure is cut to obtain individual planar light sources 301 . This completes a plurality of planar light sources 301 separated from each other.

[Features of Planar Light Source and Production Method of Planar Light Source]
According to the planar light source and the manufacturing method of the planar light source of the present embodiment, the first translucent member 31 and the second translucent member 32 are provided in the through hole 11 of the light guide plate 10 where the light source 20 is positioned. are placed. Therefore, when the first translucent member 31 is arranged and the light source 20 is electrically connected to the wiring board 201, the light source 20 is caused to emit test light, and the through hole of the unit region requiring adjustment according to the test result is detected. 11, at least one of the phosphor 35 and the light diffusing material can be added to the second translucent member 32 and arranged. Therefore, it is possible to obtain a planar light source having a structure in which at least one of the color tone distribution and the luminance distribution can be adjusted during manufacturing.

For example, even if the color tone of a light source is controlled within a predetermined standard, when a plurality of light sources are arranged on a wiring board, two light sources with biased chromaticity within the standard are arranged adjacent to each other. There is a possibility that In such a case, when all of the plurality of light sources are turned on, the units of the two light sources with uneven chromaticity are adjacent to each other, resulting in a wide distribution of regions with large uneven chromaticity. Even in such a case, according to the planar light source of the present embodiment, by adding a phosphor to the second translucent member of one or both of the two light sources of which the chromaticity is biased, the chromaticity bias can be corrected. can be reduced.

In addition, since the light from the light source 20 can enter the light guide plate 10 through the first translucent member 31 during the test emission, the test emission can be performed in a state closer to the emission of the completed planar light source 302. can be evaluated.

[Other forms]
Various modifications are possible for the planar light source of the present disclosure. For example, the planar light source may further include a third translucent member 33 . FIG. 10 shows a cross-sectional view of the planar light source 302 at a position corresponding to FIG. 3A. The planar light source 302 includes the first translucent member 31, the second translucent member 32, and the third translucent member 33 arranged in the through hole 11 in at least one of the plurality of unit regions 10U. include. Like the planar light source 301 , the first translucent member 31 is positioned on the second main surface 10 b side in the through hole 11 , is in contact with the translucent adhesive sheet 51 , and defines the through hole 11 . 11 c and the side surface 20 c of the light source 20 .

The second translucent member 32 is arranged in the through hole 11 so as to cover the upper surface 31 a of the first translucent member 31 . In the form shown in FIG. 10 , the second translucent member 32 is not located on the upper surface 20a of the light source 20. In the embodiment shown in FIG. The upper surface 32a of the second translucent member 32 is generally flat. A phosphor 35 is arranged in the second translucent member 32 . The second translucent member 32 may or may not be in contact with the side surface 11c of the through hole 11 .

The third translucent member 33 covers the upper surface 32 a of the second translucent member 32 and the upper surface 20 a of the light source 20 and is positioned inside the through hole 11 . The third translucent member 33 is in contact with the side surface 11 c that defines the through hole 11 . A lower surface 33 b of the third translucent member 33 is in contact with the upper surface 32 a of the second translucent member 32 and the upper surface 20 a of the light source 20 .

The position of the upper surface 33a of the third translucent member 33 may be the same as that of the first main surface 10a of the light guide plate 10, or the upper surface 33a may have a concave portion or a convex portion so that the light can be guided. The bottom of the concave portion of the upper surface 33a may be positioned lower than the first principal surface 10a of the light plate 10, or the convex portion of the upper surface 33a may be positioned higher than the first principal surface 10a.

A light blocking member 42 is positioned on at least a portion of the upper surface 33 a of the third translucent member 33 .

The planar light source 302 can be manufactured in the same manner as the planar light source 301 . For example, as with the planar light source 301, in the step of arranging the second translucent members (S8), the uncured second translucent members are respectively placed so as to cover at least the upper surfaces 31a of the first translucent members 31. Deploy. At this time, the phosphor 35 may be added to the uncured second translucent member in at least one of the plurality of unit regions 10U based on the results of the lighting inspection. Thereafter, the uncured second translucent member is cured to obtain the second translucent member 32 on which the phosphor 35 is arranged.

Next, an uncured third translucent member is arranged in the through hole 11 so as to cover the upper surface 32 a of the second translucent member 32 and the upper surface 20 a of the light source 20 . After that, the first translucent member 31, the second translucent member 32 and the uncured third translucent member are cured. The heating temperature for curing the uncured third translucent member is preferably 30°C to 150°C, more preferably 40°C to 130°C. Other steps can be performed in the same manner as the planar light source 301 .

According to the planar light source 302 , the first translucent member 31 , the second translucent member 32 and the third translucent member 33 are arranged inside the through hole 11 of the light guide plate 10 . Therefore, the height occupied by the third translucent member 33 in the through hole 11 can be reduced. Further, when the planar light source 302 is manufactured, the first translucent member 31 and the second translucent member 32 are cured when the uncured third translucent member 33 is arranged in the through hole 11. Therefore, the position of the lower surface 33b of the third translucent member 33 hardly decreases when the uncured third translucent member 33 is cured. For these reasons, the lowering amount of the upper surface of the uncured third translucent member 33 arranged in the through hole 11 can be reduced and can be made uniform. A member 33 can be arranged in the through hole 11 . As a result, the lower surface 42b of the light shielding member 42 can also be made flat, and the light reflected by the lower surface 42b of the light shielding member 42 can be made uniform. Therefore, the distribution of light in each light emitting unit U can be made more uniform.

A planar light source according to an embodiment of the present disclosure is useful as a planar light source for various uses. In particular, it can be advantageously applied to a backlight unit for a liquid crystal display device, and is suitable for, for example, a backlight for a display device of a mobile device where thickness reduction is strictly required, a surface emitting device capable of local dimming control, and the like. can be used.

10 Light guide plate 10U Unit area 10a First main surface 10b Second main surface 11 Through hole 11c Side surface 12 Division groove 20 Light source 20a Upper surface 20b Lower surface 20c Side surface 21 Light emitting element 21a Output surface 21b Electrode surface 21c Side surface 22 Translucent member 22a Upper surface 23 Light adjusting member 24 Coating member 25 Electrode 30 Light source 31 First translucent member 31' First translucent member 31a Upper surface 31b Lower surface 31d Concave portion 32 Second translucent member 32a Upper surface 32b Lower surface 32d First convex portion 33 3 translucent member 35 phosphor 41 light reflective material 42 light shielding member 43 light reflective sheet 51 translucent adhesive sheet 52 adhesive sheet 61 terminal 65 hole 70 wiring 80 insulating layer 101 light emitting module 101a upper surface 101b lower surface 201 wiring board 201a First main surface 201b Second main surface 301 Planar light source

Claims (14)

a first principal surface, a second principal surface located on the side opposite to the first principal surface, a plurality of unit regions arranged one-dimensionally or two-dimensionally, the first principal surface and the second principal surface a light guide plate including a plurality of through-holes that are open to and located in the plurality of unit areas;
A plurality of light sources arranged within a plurality of through holes of the light guide plate, wherein at least one of the plurality of light sources is arranged within the through hole corresponding to one of the plurality of unit areas. a light source of
a wiring board located on the second main surface side of the light guide plate and on which the plurality of light sources are arranged;
a first translucent member arranged in the through hole so as to cover at least part of a side surface of the light source in each of the plurality of unit regions;
a second translucent member arranged in the through hole covering at least the upper surface of the first translucent member in each of the plurality of unit regions;
with
In at least one of the plurality of unit regions,
the top surface of the first translucent member has a recess recessed toward the second main surface of the light guide plate at a position lower than the top surface of the light source;
A planar light source , wherein the lower surface of the second translucent member is in contact with the upper surface of the first translucent member and has a first convex portion extending toward the second main surface of the light guide plate . 2. The planar light source according to claim 1 , wherein in each of said plurality of unit areas, said first translucent member covers the entire side surface of said light source. further comprising a phosphor,
3. The planar shape according to claim 1 , wherein the phosphor is unevenly distributed on the lower surface side of the second translucent member in at least one of the plurality of unit regions. light source. 4. The planar light source according to claim 1 , wherein said second translucent member further covers the upper surface of said light source in each of said plurality of unit regions. including a plurality of light shielding members,
5. The planar light source according to claim 4 , wherein one of said plurality of light shielding members is arranged on the upper surface of said second translucent member in said through hole of said plurality of unit regions. 6. The planar light source according to claim 1 , further comprising a light reflective sheet located between said wiring board and said light guide plate and covering said second main surface of said light guide plate. the light guide plate has an opening in the first main surface and has, in a top view, partition grooves surrounding the outer peripheries of the plurality of unit regions,
7. The planar light source according to any one of claims 1 to 6 , further comprising a light reflecting member arranged in said dividing groove. preparing a wiring board having a first main surface and a second main surface opposite to the first main surface;
a first principal surface and a second principal surface located opposite to the first principal surface; a plurality of unit regions arranged one-dimensionally or two-dimensionally; arranging, on the first main surface side of the wiring board, a light guide plate including a plurality of through-holes that are open and located in the plurality of unit areas;
In the through holes of the plurality of unit regions, a plurality of light sources are arranged on the first main surface of the wiring substrate, respectively, and first translucent members are respectively arranged so as to cover at least part of side surfaces of the light sources. arranging;
disposing a second translucent member in each of the through holes of the plurality of unit regions so as to cover at least an upper surface of the first translucent member;
including
In at least one of the plurality of unit regions,
the top surface of the first translucent member has a recess recessed toward the second main surface of the light guide plate at a position lower than the top surface of the light source;
A method for manufacturing a planar light source , wherein the lower surface of the second translucent member is in contact with the upper surface of the first translucent member and has a first convex portion extending toward the second main surface of the light guide plate . Between the step of arranging the first translucent member and the step of arranging the second translucent member,
electrically connecting the plurality of light sources and the wiring board;
turning on the plurality of light sources and inspecting light emitted from the plurality of light sources;
including
9. The step of disposing the second translucent member includes adding a phosphor to the second translucent member in at least one of the plurality of unit regions based on the results of the inspecting step. 2. The method for manufacturing the planar light source according to 1. 10. The method of manufacturing a planar light source according to claim 9, wherein in said second translucent member, said phosphor is unevenly distributed on the lower surface side of said second translucent member. a step of forming, in the light guide plate, partition grooves that have openings in the first main surface of the light guide plate and surround outer peripheries of the plurality of unit regions when viewed from above;
arranging a light reflecting member in the dividing groove;
11. The method of manufacturing a planar light source according to any one of claims 8 to 10 , further comprising 12. The method of manufacturing a planar light source according to claim 8 , further comprising the step of placing a light shielding member on the upper surface of the second translucent member after the step of placing the second translucent member. 13. The method of manufacturing a planar light source according to claim 8 , wherein in each of said plurality of unit regions, said first translucent member covers the entire side surface of said light source. 14. The method of manufacturing a planar light source according to claim 8 , wherein in each of said plurality of unit regions, said second translucent member further covers the upper surface of said light source.

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