JP2022142639A - Surface light source and surface light source module - Google Patents

Abstract

To provide a surface light source in which the occurrence of color unevenness is suppressed.SOLUTION: A surface light source 200A includes: a wiring board 10; at least one light emitting element 20 arranged on the wiring board; a light reflecting member 30A arranged on the wiring board and covering the side surface of the light emitting element; a light guide layer 40 arranged on the light emitting element and the light reflecting member; a wavelength conversion layer 50 arranged above the light guide layer; and a colored layer 60A positioned between the light guide layer and the wavelength conversion layer and positioned around the light emitting element in plan view, and absorbing light having a specific wavelength.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to planar light sources and planar light source modules.

Patent Document 1 below discloses a light-emitting device in which side surfaces of a plurality of light-emitting elements on a substrate are covered with a light-reflecting member. By covering the side surface of the light emitting element with the light reflecting member, leakage of light from the side surface of the light emitting element is suppressed, and as a result, it becomes possible to improve the light extraction efficiency. In the light-emitting device of Patent Document 1, a light-transmitting layer containing a phosphor is arranged above a structure in which the side surface of the light-emitting element is covered with a light-reflecting member.

JP 2015-106641 A

It would be beneficial to be able to suppress the color unevenness from becoming more pronounced as the light extraction efficiency is improved.

In a non-limiting exemplary embodiment, the planar light source of the present disclosure includes a wiring substrate, at least one light-emitting element arranged on the wiring substrate, and the light-emitting element arranged on the wiring substrate. a light reflective member covering a side surface, a light guide layer disposed on the light emitting element and the light reflective member, a wavelength conversion layer disposed above the light guide layer, the light guide layer and the wavelength a colored layer positioned between the conversion layer and around the light emitting element in a plan view, the colored layer absorbing light having a specific wavelength.

According to exemplary embodiments of the present disclosure, it is possible to provide a planar light source in which color unevenness on the light emitting surface is suppressed.

1 is a schematic cross-sectional view of a planar light source according to certain embodiments of the present disclosure; FIG. FIG. 4 is a schematic plan view showing an example of the shape of a colored layer; 2 is a diagram schematically showing a cross section of a planar light source module including the planar light source shown in FIG. 1 as part thereof; FIG. FIG. 4 is a schematic plan view showing another example of the shape of a colored layer; FIG. 4 is a schematic plan view for explaining an example of the arrangement of light emitting elements on a wiring board; FIG. 6 is a diagram schematically showing a wiring pattern of an area including 4×4 segments surrounded by a dashed rectangle shown in FIG. 5; 7 is a diagram for explaining a wiring pattern in the segment area shown in FIG. 6; FIG. It is a typical figure for explaining an example of a plane view shape of a light adjustment layer. FIG. 5 is a schematic diagram for explaining another example of the planar view shape of the light adjustment layer. FIG. 4 is a schematic plan view for explaining an example of a light reflection pattern that can be applied to the light adjustment layer; FIG. 4 is a schematic cross-sectional view of a planar light source according to another embodiment of the present disclosure; FIG. 4 is a schematic plan view showing an example of arrangement of convex portions as a light shielding structure; FIG. 10 is a schematic plan view showing another example of arrangement of convex portions as a light shielding structure; FIG. 10 is a schematic cross-sectional view showing another example of the cross-sectional shape of a convex portion as a light shielding structure; FIG. 10 is a schematic cross-sectional view showing still another example of the cross-sectional shape of the convex portion as the light shielding structure; FIG. 5 is a schematic cross-sectional view of a planar light source according to still another embodiment of the present disclosure; FIG. 5 is a schematic cross-sectional view of a planar light source according to still another embodiment of the present disclosure; 4A to 4D are process cross-sectional views for explaining an exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure; 4A to 4D are process cross-sectional views for explaining an exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure; 4A to 4D are process cross-sectional views for explaining an exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure; 4A to 4D are process cross-sectional views for explaining an exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure; 4A to 4C are process cross-sectional views for explaining another exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure; 4A to 4C are process cross-sectional views for explaining another exemplary manufacturing method of the planar light source according to the embodiment of the present disclosure;

Hereinafter, 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 planar light source module 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 the components shown in the drawings may be exaggerated for clarity, and reflect the dimensions, shapes, and size relationships between the actual planar light source and planar light source module. may not. In addition, in order to avoid making the drawings overly complicated, there are cases where illustration of some elements is omitted and shown schematically, or end views showing only cut surfaces are shown as cross-sectional views.

In the following description, constituent elements having substantially the same functions are denoted by common reference numerals, and descriptions thereof may be omitted. The following description may use terms (eg, "upper", "lower", "right", "left" and other terms that include those terms) that indicate particular directions or positions. However, these terms are only used 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.

[1. Structure of planar light source 200A]
FIG. 1 shows a schematic cross-section of a planar light source according to certain embodiments of the present disclosure. For reference, FIG. 1 shows X, Y and Z directions which are orthogonal to each other. Other drawings in this disclosure may also show these directions.

In an embodiment of the present disclosure, the planar light source includes at least a wiring board, at least one light emitting element arranged on the wiring board, and a light reflecting member. A planar light source 200A shown in FIG. 1 includes a wiring board 10, a plurality of light emitting elements 20 arranged on the wiring board 10, and a light reflecting member 30A covering the side surfaces of the light emitting elements 20. FIG.

FIG. 1 shows an example in which a plurality of light emitting elements 20 including a first light emitting element 21 and a second light emitting element 22 are mounted on a wiring board 10. As shown in FIG. The light reflective member 30A is arranged on the wiring board 10 and covers the side surfaces 20c of the first light emitting element 21 and the second light emitting element 22 collectively. Note that FIG. 1 schematically shows the first light emitting element 21 and the second light emitting element 22 and their surroundings from the cross section of the planar light source 200A. As will be described later, the light emitting elements 20 can be arranged on the wiring substrate 10 not only along the X direction of the drawing, but also along the Y direction of the drawing. In other words, the plurality of light emitting elements 20 can be two-dimensionally arranged on the upper surface 10 a of the wiring board 10 .

200 A of planar light sources further have the light guide layer 40, the wavelength conversion layer 50, and 60 A of coloring layers. The light guide layer 40 is disposed over the first light emitting element 21 and the second light emitting element 22 and the light reflecting member 30A and on the top surface of these members. In other words, the light guide layer 40 collectively covers the upper surface 21a of the first light emitting element 21, the upper surface 22a of the second light emitting element 22, and the upper surface 30a of the light reflecting member 30A. The wavelength conversion layer 50 is located above the light guide layer 40 and contains a wavelength conversion member such as phosphor particles. The thickness of the entire planar light source 200A, that is, the distance in the Z direction from the lower surface 10b of the wiring board 10 to the upper surface 50a of the wavelength conversion layer 50 can be about 1 mm or less. As will be described later, when the planar light source 200A is applied particularly to a backlight, an optical sheet such as a prism sheet may be further arranged above the upper surface 50a of the wavelength conversion layer 50. FIG.

Colored layer 60A is provided between light guide layer 40 and wavelength conversion layer 50 . Here, the colored layer 60A is arranged on the upper surface 40a of the light guide layer 40. As shown in FIG. As will be described in detail later with reference to the drawings, the colored layer 60A has neither a portion overlapping the upper surface 21a of the first light emitting element 21 nor a portion overlapping the upper surface 22a of the second light emitting element 22 in plan view. . In addition, in the configuration illustrated in FIG. 1 , the planar light source 200A further has a light adjustment layer 70A positioned substantially directly above each light emitting element 20 . In the example shown in FIG. 1, the light adjustment layer 70A is arranged between the light guide layer 40 and the wavelength conversion layer 50 in the Z direction in the figure, like the colored layer 60A.

FIG. 2 shows an example of the shape of the colored layer 60A. FIG. 2 schematically shows the appearance of the planar light source 200A shown in FIG. 1 when the wavelength conversion layer 50 and the light adjustment layer 70A are removed and the planar light source 200A is viewed in the direction normal to the upper surface 40a of the light guide layer 40. shown in

In the configuration illustrated in FIG. 2 , the colored layer 60A includes a plurality of island-shaped portions (first dots) arranged on the upper surface 40a of the light guide layer 40 . These multiple portions of the colored layer 60A are arranged around the light emitting elements (here, the first light emitting element 21 and the second light emitting element 22) in plan view.

60 A of colored layers are comprised so that light which has a specific wavelength can be absorbed. For example, the colored layer 60A contains a pigment of a specific color, thereby absorbing components of a certain wavelength range in the light incident on the colored layer 60A. In this case, for example, when white light is incident on the colored layer 60A, the reflected light from the colored layer 60A becomes light in which a component in a specific wavelength range is removed from the white light. That is, in this embodiment, the reflected light from the colored layer 60A is basically not white light.

By arranging the colored layer 60A between the light guide layer 40 and the wavelength conversion layer 50 as in the embodiment of the present disclosure, the optical sheet positioned above the wavelength conversion layer 50 and the light guide layer 40 It is possible to suppress the occurrence of color unevenness due to repeated reflection of the light. This point will be described below with reference to the drawings.

FIG. 3 schematically shows an example of a planar light source module partly including the planar light source shown in FIG. A planar light source module 300 shown in FIG. 3 includes the planar light source 200A described above and a translucent laminate 90 arranged above the wavelength conversion layer 50 . In the configuration illustrated in FIG. 3 , the translucent laminate 90 includes a light diffusion sheet 80 positioned above the wavelength conversion layer 50 and a prism sheet 85 positioned above the light diffusion sheet 80 . In this example, the prism sheet 85 has a laminated structure with prism array layers 81 and 82 .

As described above, the wavelength conversion layer 50 positioned above the first light emitting element 21 and the second light emitting element 22 typically contains wavelength converting members such as phosphor particles. The wavelength conversion layer 50 absorbs at least part of the light emitted from these light emitting elements and passing through the light guide layer 40, and emits light with a wavelength different from the wavelength of the light emitted from the light emitting elements. For example, when the first light emitting element 21 and the second light emitting element 22 are elements that emit blue light, the wavelength conversion layer 50 converts the wavelength of part of the blue light as excitation light from these light emitting elements. emits a yellow light. According to such a configuration, white light is obtained by mixing the blue light that has passed through the wavelength conversion layer 50 and the yellow light emitted from the wavelength conversion layer 50 .

In a structure that obtains white light by mixing blue light and, for example, yellow light obtained by excitation of a phosphor, as the distance traveled through a member (phosphor layer) in which the phosphor is dispersed increases, the amount of light emitted from the member increases. long-wavelength components in the emitted light tend to increase. For example, in a configuration in which a phosphor layer is arranged above a light emitting element, light that is emitted from the light emitting element and obliquely incident on the phosphor layer is incident on the phosphor layer on the optical axis of the light emitting element. It propagates a longer distance inside the phosphor layer compared to light that is normally incident on the surface of the phosphor layer. Therefore, light emitted from a region of the upper surface of the phosphor layer located away from the light emitting element in plan view may be yellowish. In other words, color unevenness may occur between a region of the upper surface of the phosphor layer that is distant from the light emitting element and a region that is near the light emitting element in plan view. This tendency becomes more pronounced as the thickness of the phosphor layer increases.

In particular, if an optical sheet such as a prism sheet is further arranged above the phosphor layer, the light reflected by the lower surface of the optical sheet may enter the phosphor layer again. A component of such light that is reflected, for example, at a position on the lower surface of the phosphor layer and directed toward the upper surface of the phosphor layer propagates a longer distance inside the phosphor layer. That is, the light that is finally extracted from the phosphor layer after being incident on the phosphor layer multiple times contains more components obtained by wavelength conversion (for example, yellow light). Color shifts are more noticeable for light that passes through vertically.

In the configuration illustrated in FIG. 3, the light represented by the solid arrow Ry1 in FIG. is incident. At least part of such light is reflected at positions such as the upper surface 40 a of the light guide layer 40 and directed toward the light-transmitting laminate 90 again. In applications such as a backlight, when light incident from the upper surface 50a side of the wavelength conversion layer 50 is extracted again to the upper surface 50a side of the wavelength conversion layer 50, light having a color temperature lower than the desired color temperature is emitted from the liquid crystal panel. etc. will be introduced.

However, in this embodiment, the colored layer 60A is arranged between the wavelength conversion layer 50 and the light guide layer 40 in a cross-sectional view. Therefore, part of the light incident from the upper surface 50a side of the wavelength conversion layer 50 is reflected by the colored layer 60A and transmitted through the wavelength conversion layer 50 as indicated by the solid arrow Ry2 in FIG. Turn to laminate 90 .

60 A of colored layers absorb the light which has a specific wavelength, for example by containing a pigment, as mentioned above. For example, if the colored layer 60A contains a pigment that absorbs components in the yellow wavelength range, that is, a blue pigment, the colored layer 60A emits light with reduced yellow wavelength components. Therefore, it is possible to obtain the effect of reducing the component of the yellow wavelength region contained in the light emitted from the wavelength conversion layer 50, and it is possible to suppress the occurrence of color unevenness.

Hereinafter, each component of the planar light source and the planar light source module according to the embodiments of the present disclosure will be described in detail. Hereinafter, for convenience of explanation, the first light emitting element 21 and the second light emitting element 22 may be collectively referred to as the "light emitting element 20".

(First Light Emitting Element 21, Second Light Emitting Element 22)
The light emitting element 20 includes a semiconductor laminate. The semiconductor laminate includes an n-type semiconductor layer, a p-type semiconductor layer, and a light-emitting layer sandwiched therebetween. 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 active layers such as a multiple quantum well (MQW). good. The light-emitting layer of the semiconductor laminate is configured to emit visible light or ultraviolet light. A semiconductor laminate having such a light-emitting layer can contain, for example, InxAlyGa1 _-xyN (0≤x, _0≤y , _x +y≤1).

The semiconductor laminate may have a structure including one or more light-emitting layers between an n-type semiconductor layer and a p-type semiconductor layer, or may have an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. A structure containing in order may have a structure repeated multiple times. When the semiconductor laminate includes a plurality of light-emitting layers, the plurality of light-emitting layers 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. A combination of emission peak wavelengths between a plurality of light-emitting layers can be selected as appropriate. For example, when the semiconductor laminate includes two light-emitting layers, the combinations of light emitted from these light-emitting layers include 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, or green light and red light, etc. can be selected. 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. A blue LED that emits blue light is exemplified below as the light emitting element 20 .

The light emitting element 20 has an upper surface (an upper surface 21a or 22a), a lower surface 20b positioned opposite to the upper surface, and a side surface 20c positioned between the upper surface and the lower surface 20b. Each side surface 20c of one or more light emitting elements 20 arranged on the wiring board 10 is covered with a light reflecting member 30A, and light from the light emitting elements 20 is mainly extracted from the upper surface thereof.

Light emitting element 20 is typically a bare chip. The height of the light emitting element 20 (the distance in the Z direction from the upper surface 10a of the wiring board 10 to the upper surface of the light emitting element 20) is, for example, approximately 0.425 mm. A positive electrode 2 a and a negative electrode 2 c are provided on the lower surface 20 b of the light emitting element 20 . The positive electrode 2a and the negative electrode 2c are electrically connected to the p-type semiconductor layer and the n-type semiconductor layer in the semiconductor laminate, respectively.

(Light reflective member 30A)
A light reflective member 30A arranged on the wiring board 10 covers the upper surface 10a of the wiring board 10 and the side surfaces 20c of the light emitting elements 20, respectively. The light reflecting member 30A is made of, for example, a resin material containing reflective particles. As the base material of the light reflecting member 30A, a photocurable resin such as an acrylate resin, or a thermosetting resin such as an epoxy resin or a silicone resin can be applied. As will be described later, a light-reflective resin sheet whose base material is polyethylene terephthalate (PET) or the like may be applied to the light-reflective member 30A. Examples of reflector particles are particles of oxides such as titanium oxide, aluminum oxide, silicon oxide, zinc oxide, and the like. The average particle size of the oxide particles is, for example, about 0.05 μm or more and 30 μm or less. The light reflecting member 30A may further contain pigments, light absorbing materials, phosphors, and the like. The light-scattering reflective particles may be distributed throughout the light-reflective member 30A.

The light reflecting member 30A has a function of protecting the plurality of light emitting elements 20. As shown in FIG. In addition, it has a function of emitting light mainly from the upper surface of each light emitting element 20 by reflecting light emitted from the side surface 20c of each light emitting element 20 in particular. As a result, it is possible to efficiently introduce light into the light guide layer 40, which will be described later.

Since the light reflecting member 30A has light reflectivity, the light coming from the light-transmitting laminate 90 side can be reflected on the upper surface 30a. As a result, the light traveling toward the wiring substrate 10 inside the light guide layer 40 is effectively used, and the light emitting surface of the planar light source 200A and the planar light source module 300 (the upper surface 50a of the wavelength conversion layer 50 or the light-transmitting laminate) is effectively utilized. The brightness at the upper surface 90a) of the body 90 can be improved. Here, in this specification, the term “light reflectivity” refers to a reflectance of 60% or more at the emission peak wavelength of the light emitting element 20 . It is more beneficial if the reflectance of the light reflecting member 30A at the emission peak wavelength of the light emitting element 20 is 70% or more, and even more beneficial if it is 80% or more.

The upper surface 30a of the light reflecting member 30A is, for example, a flat surface as shown in FIG. However, it is not essential in the embodiments of the present disclosure that the upper surface 30a of the light reflecting member 30A is flat. As will be described later, the upper surface 30a may have one or more concave surfaces. Also, one or more protrusions may be formed on the upper surface 30a.

The light reflecting member 30A may include a portion located between the lower surface 20b of the light emitting element 20 and the upper surface 10a of the wiring board 10. As shown in FIG. The light reflecting member 30A is formed, for example, to fill the gap between the lower surface 20b of the light emitting element 20 and the upper surface 10a of the wiring board 10, thereby covering the positive electrode 2a and the negative electrode 2c of the light emitting element 20. good. By arranging a part of the light reflecting member 30A also on the side of the lower surface 20b of the light emitting element 20, the light directed toward the upper surface 10a of the wiring board 10 can be reflected toward the side of the upper surface 30a of the light reflecting member 30A. . As a result, the utilization efficiency of the light emitted from the light emitting element 20 can be further improved. In addition, by arranging a part of the light reflecting member 30A between the lower surface 20b of the light emitting element 20 and the upper surface 10a of the wiring board 10, the heat dissipation between the light emitting element 20 and the wiring board 10 is improved. Effects such as relaxation of stress that may occur due to differences in expansion coefficients can also be expected.

(Light guide layer 40)
The light guide layer 40 is a translucent member arranged on the light emitting element 20 and the light reflecting member 30A. The thickness of the light guide layer 40, in other words, the distance in the Z direction from the top surface of the light emitting element 20 or the top surface 30a of the light reflecting member 30A to the top surface 40a of the light guide layer 40 can be, for example, about 200 μm.

As the material of the light guide layer 40, for example, an acrylic resin, a polycarbonate resin, an epoxy resin, a silicone resin, or a resin material in which these are mixed can be used. Here, the terms “translucent” and “translucent” in this specification are interpreted to include showing diffusing properties for incident light, and are not limited to being “transparent”. . For example, the light guide layer 40 may have a light diffusion function by dispersing a material having a refractive index different from that of the base material. A light diffusion function may be imparted to the light guide layer 40 by dispersing particles such as titanium oxide, aluminum oxide, silicon oxide, and zinc oxide as a light diffusion material in the base material. An air layer may be used as the light guide layer 40 .

(Colored layer 60A)
60 A of colored layers are located between the light guide layer 40 and the wavelength conversion layer 50 mentioned later, and are comprised so that the light which has a specific wavelength may be absorbed (or the light which has a specific wavelength may be reflected). . The colored layer 60A is formed by, for example, applying a resin material containing a pigment or dye of a specific color to the upper surface 40a of the light guide layer 40 and then curing the applied resin material. placed above. The base material of the colored layer 60A can be acrylic resin, polycarbonate resin, epoxy resin, silicone resin, or a mixture thereof, similarly to the light guide layer 40 .

When a blue LED that emits blue light is used as the light emitting element 20, a blue pigment can be used as the pigment mixed in the base material of the colored layer 60A. Known materials such as copper phthalocyanine can be applied to the blue pigment. As the material of the colored layer 60A, for example, a resin material containing 0.01 wt % to 5 wt % of a blue pigment having a particle size of 0.02 μm to 1 μm can be used. By including a blue pigment in the colored layer 60A, it is possible to reduce the component in the yellow wavelength region contained in the light that enters from the upper surface 60a side of the colored layer 60A and is reflected by the colored layer 60A. As a result, of the light having a relatively long propagation distance in the wavelength conversion layer 50, the light reflected by the colored layer 60A is reduced in the component of the yellow wavelength region, and thus the light propagates in the wavelength conversion layer 50. The effect of wavelength shift with increasing distance is canceled out. As a result, the yellowishness of the light emitted from the light emitting surface of the planar light source 200A or the planar light source module 300, which is distant from the optical axis L of the light emitting element 20 in plan view, is suppressed, and the color unevenness on the entire light emitting surface is reduced. The effect of suppressing the occurrence is obtained. The color of the pigment to be contained in the colored layer 60A can be appropriately selected according to the color of the light emitted from the light emitting element 20. FIG.

As can be understood from the mechanism for suppressing color unevenness described above, the colored layer 60A typically does not have a portion that overlaps the optical axis L of the light emitting element 20 in plan view. located around For example, in the example shown in FIG. 2, the colored layer 60A includes a plurality of island-shaped portions arranged at positions away from the optical axis L of each light emitting element 20 mounted on the wiring board 10. there is

In the configuration illustrated in FIG. 2 , the colored layer 60A includes multiple first portions 61 , multiple second portions 62 , multiple third portions 63 and multiple fourth portions 64 . Here, each of the first portions 61, each of the second portions 62, each of the third portions 63, and each of the fourth portions 64 are circular dots. The diameter of each dot forming colored layer 60A increases in order of first portion 61, second portion 62, third portion 63 and fourth portion 64. FIG. For example, the diameter of the dots of the first portion 61 can be about 0.1 mm.

In the example shown in FIG. 2, each portion constituting the colored layer 60A is located on a lattice point of the square lattice or at the center of the unit cell of the square lattice. The positions of the optical axis L of the first light emitting element 21 and the optical axis L of the second light emitting element 22 are also substantially aligned with the center of the unit cell of the square lattice. As will be described later, in the embodiment of the present disclosure, a light adjustment layer may be further provided at a position overlapping the optical axis L of each light emitting element 20 in plan view (see light adjustment layer 70A in FIG. 1). Although the light adjustment layer 70A is not drawn in FIG. 2, in a configuration having the light adjustment layer 70A, it can be said that each portion constituting the colored layer 60A is arranged around the light adjustment layer 70A.

Of the plurality of light emitting elements 20, attention is focused on the unit centering on the first light emitting element 21. FIG. In this example, four first portions 61 and four second portions 62 are arranged around the first light emitting element 21, and a plurality of third portions 63 are arranged so as to surround them. there is A fourth portion 64 is positioned outside the plurality of third portions 63 . These first to fourth portions 61 to 64 are arranged symmetrically about the first light emitting element 21. In the configuration illustrated in FIG. can be said to be arranged concentrically around the first light-emitting element 21 in . Each part constituting the colored layer 60A may be arranged concentrically around the light emitting element 20 in plan view.

As described above, in the example shown in FIG. 2, the dot diameter increases in the order of the first portion 61, the second portion 62, the third portion 63, and the fourth portion 64. FIG. As a result, the area ratio of the dots forming the colored layer 60A to the unit area (ratio of the area occupied by the dots forming the colored layer 60A per unit area) increases as the distance from the first light emitting element 21 increases. In other words, in a unit centered on the first light emitting element 21, the ratio of the area of the upper surface 40a of the light guide layer 40 that is not covered with the dots forming the colored layer 60A (also referred to as the aperture ratio) is It becomes smaller as the distance from the first light emitting element 21 increases.

As in this example, by increasing the area of the region occupied by the colored layer 60A as the distance from the first light emitting element 21 increases, the light travels from a position farther from the first light emitting element 21 to above the planar light source or the planar light source module. It is possible to effectively reduce specific wavelength components (for example, components in the yellow wavelength range) contained in the emitted light. As a result, it is possible to suppress the occurrence of color unevenness on the light emitting surface (for example, the upper surface 90a of the translucent laminate 90).

Instead of increasing the dot diameter away from the optical axis L of the light emitting element 20, the dot diameters of the first portion 61, the second portion 62, the third portion 63 and the fourth portion 64 are approximately equal to While being the same, the number of dots may increase with increasing distance from the light emitting element 20 . In other words, the dot number density may increase as the distance from the light emitting element 20 increases. With such a configuration as well, the effect of reducing the ratio of light having a specific wavelength (eg, yellow light) according to the distance from the light emitting element 20 can be expected. The dot number density can be defined by the number of dots whose centers are included in a unit area on the XY plane.

FIG. 4 schematically shows another example of the shape of the colored layer. The colored layer 60B shown in FIG. 4 includes a plurality of dot-shaped first portions 61, a plurality of dot-shaped second portions 62, and a plurality of dot-shaped third portions 63, each having a circular shape. I'm in. Similar to the example described with reference to FIG. 2, the circular diameter increases in the order of the first portion 61, the second portion 62 and the third portion 63. FIG.

In the example shown in FIG. 4, the center of each dot and the light emitting element 20 forming the colored layer 60B is located on the lattice point of the hexagonal lattice or at the center of the unit cell of the hexagonal lattice. Focusing on the unit cell located next to the unit cell containing the first light emitting element 21, the first portion 61 is arranged on the lattice point located closest to the first light emitting element 21, A third portion 63 is arranged on the furthest grid point. Similarly to the example described with reference to FIG. 2, also in this example, the aperture ratio decreases as the distance from the optical axis L of the light emitting element 20 decreases, and it is possible to obtain the effect of suppressing color unevenness on the light emitting surface. be. When the colored layer includes a plurality of parts, the shape of each part is not limited to a circular shape, and any shape such as a square shape, a polygonal shape, or the like can be adopted according to the required optical characteristics.

(Wavelength conversion layer 50)
As shown in FIGS. 1 and 3 , a wavelength conversion layer 50 is arranged above the light guide layer 40 . The wavelength conversion layer 50 is supported above the light guide layer 40 by a frame arranged on the wiring board 10 or a housing or the like that accommodates the wiring board 10 and the structure on the wiring board 10 . The lower surface 50b of the wavelength conversion layer 50 may be in contact with the upper surface 40a of the light guide layer 40 or the upper surface 60a of the colored layer. You may have Here, an air layer is formed in the space between the lower surface 50 b of the wavelength conversion layer 50 and the upper surface 40 a of the light guide layer 40 . A translucent resin member or the like may be further disposed between the lower surface 50b of the wavelength conversion layer 50 and the upper surface 40a of the light guide layer 40 .

A typical example of the wavelength conversion layer 50 is a phosphor sheet containing resin and phosphor particles. The wavelength conversion layer 50 absorbs at least part of the light emitted from the light emitting element 20 and passed through the light guide layer 40 , and emits light with a wavelength different from the wavelength of the light emitted from the light emitting element 20 . For example, the wavelength conversion layer 50 wavelength-converts part of the blue light from the light emitting element 20 to emit yellow light. The thickness of the wavelength conversion layer 50 can be, for example, in the range of 100 μm or more and 200 μm or less. The thickness of the wavelength conversion layer 50 in embodiments of the present disclosure may be, for example, approximately 100 μm.

The base material of the wavelength conversion layer 50 contains silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, urea resin, phenol resin, acrylic resin, urethane resin, fluorine resin, or two or more of these resins. Resin can be used. A light diffusion function may be imparted to the wavelength conversion layer 50 by including a material having a refractive index different from that of the base material in the material of the wavelength conversion layer 50 . For example, particles of titanium oxide, aluminum oxide, silicon oxide, zinc oxide, or the like may be dispersed as a light diffusion material in the base material of the wavelength conversion layer 50 .

A known material can be applied to the phosphor. Examples of phosphors in the wavelength conversion layer 50 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., Tb ₃ (Al, Ga) ₅ O ₁₂ :Ce), CCA-based phosphors (e.g., Ca ₁₀ (PO ₄ ) _6Cl2 :Eu), _SAE phosphors ₍ e.g. _Sr4Al14O25 : _Eu ), _{chlorosilicate} phosphors ₍ e.g. _{Ca8MgSi4O16Cl2} : _Eu ), nitride phosphors phosphors, fluoride-based phosphors, phosphors having a perovskite structure (e.g. CsPb(F,Cl,Br,I) ₃ ), quantum dot phosphors (e.g. CdSe, InP, AgInS ₂ or AgInSe ₂ ), etc. be able to. Examples of nitride phosphors include β-sialon phosphors (eg, (Si, Al) ₃ (O, N) ₄ :Eu), α-sialon phosphors (eg, Ca(Si, Al) ₁₂ (O , N) ₁₆ :Eu), SLA-based phosphors (eg, SrLiAl ₃ N ₄ :Eu), CASN-based phosphors (eg, CaAlSiN ₃ :Eu) and SCASN-based phosphors (eg, (Sr, Ca)AlSiN ₃ :Eu), etc. Examples of fluoride-based phosphors include KSF-based phosphors (e.g., K ₂ SiF ₆ :Mn) and KSAF-based phosphors (e.g., K ₂ (Si, Al) F ₆ :Mn). and MGF-based phosphors (eg, 3.5MgO·0.5MgF ₂ ·GeO ₂ :Mn).

In an exemplary embodiment of the present disclosure, a wavelength conversion layer 50 is provided over the plurality of light emitting elements 20 in the form of a phosphor layer collectively covering them. According to the configuration in which the wavelength conversion layer 50 is arranged above the light guide layer 40 , the light introduced into the light guide layer 40 can first be diffused inside the light guide layer 40 and then enter the wavelength conversion layer 50 . can. This makes it possible to more effectively suppress color unevenness on the light emitting surface.

(Wiring board 10)
The wiring board 10 has an upper surface 10a and a lower surface 10b. A plurality of light emitting elements 20 are arranged and supported on the upper surface 10a side of the wiring board 10 . The wiring board 10 has a plurality of wiring layers each having a wiring pattern, an insulating portion 11 and vias 13 . In the configuration illustrated in FIGS. 1 and 3, the wiring board 10 includes a first wiring layer 12a and a second wiring layer 12b. The first wiring layer 12 a and the second wiring layer 12 b are electrically connected to each other through vias 13 provided in the insulating portion 11 . A part of the insulating part 11 covers the area of the upper surface 10a of the wiring board 10 other than the area where the light emitting element 20 is mounted. A typical example of the wiring board 10 is a flexible printed circuit board (FPC). The thickness of the wiring board 10 (the distance from the upper surface 10a to the lower surface 10b in the Z direction in the drawing) can be about 0.17 mm. In this specification, the wiring pattern means any shape of the conductor such as a film shape, a plate shape, or the like.

Materials for the insulating portion 11 of the wiring board 10 include resin materials such as phenol resin, epoxy resin, polyimide resin, BT resin, polyphthalamide (PPA), and polyethylene terephthalate (PET). As the material of the insulating portion 11 of the wiring board 10, composite materials such as glass fiber reinforced resin (glass epoxy resin) or ceramics can be used. Materials for the wiring layers (here, the first wiring layer 12a and the second wiring layer 12b) are appropriately selected according to the material used for the insulating portion 11 of the wiring board 10, the manufacturing method, and the like. An insulating film such as a solder resist may be arranged on the wiring layer.

The first wiring layer 12 a is provided on the upper surface 10 a side of the wiring substrate 10 . A positive electrode (anode) 2a and a negative electrode (cathode) 2c of each of the plurality of light emitting elements 20 are electrically connected to the first wiring layer 12a. On the other hand, the second wiring layer 12b is provided on the side of the lower surface 10b of the wiring board 10 . As will be described later, the second wiring layer 12b has connections with connectors for connection with external control circuits.

FIG. 5 schematically shows an exemplary appearance of the structure of planar light source 200A shown in FIG. The schematic cross section shown in FIG. 1 corresponds to a part of the cross section taken along the line II shown in FIG.

In the example shown in FIG. 5, a plurality of light emitting elements 20 including a first light emitting element 21 and a second light emitting element 22 are two-dimensionally arranged along two mutually orthogonal directions (here, the X direction and the Y direction). there is More specifically, a total of 676 light emitting elements 20 are arranged in 26 rows and 26 columns. In this example, 26 light emitting elements 20 are arranged along the X direction and 26 light emitting elements 20 are arranged along the Y direction.

In the configuration illustrated in FIG. 5, the light emitting elements 20 are arranged such that the arrangement pitch px in the X direction and the arrangement pitch py in the Y direction are equal to each other. Here, the arrangement pitch of the light emitting elements 20 means the distance between the optical axes L of two adjacent light emitting elements 20 . As schematically shown in FIG. 1, the optical axis L is perpendicular to the emission surface (upper surface) of the light emitting element 20 . Each of the arrangement pitches px and py can be set to 0.5 mm or more and 10 mm or less. In embodiments of the present disclosure, each of the array pitches px and py may be on the order of 2.0 mm.

Of course, the arrangement of the plurality of light emitting elements 20 is not limited to this example. The arrangement pitch is not limited to equal intervals, and may be irregular intervals. For example, a plurality of light emitting elements 20 may be arranged so that the distance between them increases from the center of the wiring board 10 toward the periphery. The arrangement pitch of the light emitting elements 20 may be different between the X direction and the Y direction, and the two directions of the two-dimensional arrangement of the plurality of light emitting elements 20 may not be orthogonal.

As illustrated in FIG. 5, the light reflecting member 30A covering the side surface of each light emitting element 20 located on the wiring board 10 has a rectangular plan view shape. The X-direction length Lx1 and the Y _- direction length _Ly1 of the light reflecting member 30A are, for example, about 52 mm. In the upper surface 10a of the wiring board 10, the X-direction length Lx2 of the region where the light reflecting member 30A is provided is, for example, about 55 mm, and the Y _- direction length _Ly2 is, for example, about 60 mm.

In the configuration illustrated in FIG. 5, it can be said that the planar light source 200A has a repeating structure of a total of 676 units each having one light emitting element 20 . Hereinafter, for convenience of explanation, a unit having one light emitting element may be called a segment or an individual region.

FIG. 6 schematically shows a wiring layer of a region (hereinafter sometimes simply referred to as “segment region”) including 4×4 segments surrounded by the dashed rectangles shown in FIG. 5 . The 676 light emitting elements 20 arranged two-dimensionally are electrically connected to the first wiring layer 12a. As schematically shown in FIG. 6, the first wiring layer 12a includes a plurality of first wirings PA1 each extending in the X direction, and a plurality of sets of anode-side lands 15a and cathode-side lands 15b. there is The land 15a and the land 15b are portions of the first wiring layer 12a to which the positive electrode 2a and the negative electrode 2c of the light emitting element 20 in each segment are connected, respectively. Here, a plurality of first wirings PA1 are arranged along the column direction (Y direction) of an array of 4 rows and 4 columns of segments, and the first wirings PA1 of each row are arranged with a plurality of lands 15a located in the same row. have a connection between That is, each first wiring PA1 electrically connects the positive electrodes 2a of the plurality of light emitting elements 20 located in the same row.

The first wiring layer 12a also has a plurality of second wirings PC2. As shown in FIG. 6, the plurality of second wirings PC2 are provided for each segment, and each of the plurality of second wirings PC2 is connected to the corresponding cathode-side land 15b.

Each of the first wiring PA1 and the second wiring PC2 of the first wiring layer 12a is connected to the second wiring layer 12b via the via 13 . The second wiring layer 12b includes third wirings PA3 extending along the Y direction and fourth wirings PC4 provided for each segment.

FIG. 7 shows an exemplary connection relationship between wiring layers and connectors in the segment area. As schematically shown in FIG. 7, the plurality of first wirings PA1 of the first wiring layer 12a are commonly connected to the third wiring PA3 via the vias 13. As shown in FIG. The third wiring PA3 is connected to the connector 18 . That is, due to this connection relationship, a common drive signal can be supplied to the positive electrodes 2a of all the light emitting elements 20 from the third wiring PA3.

On the other hand, the second wiring PC2 of the first wiring layer 12a provided for each segment is electrically connected through the via 13 to a corresponding one of the plurality of fourth wirings PC4. As shown in FIG. 7, each of the plurality of fourth wirings PC4 is connected to the connector 18. As shown in FIG. Due to this connection relationship, the voltage drive signal can be supplied to the negative electrode 2c of the light emitting element 20 in units of segments via the fourth wiring PC4.

Such an electrical connection relationship allows power to be supplied to the plurality of light emitting elements 20 from an external control circuit (not shown) via the connector 18 of the wiring board 10 . According to the anode and cathode wiring patterns described with reference to FIGS. 6 and 7, it is possible to drive the light emitting element 20 in units of segments. The planar light source 200A and the planar light source module 300 can be configured for local dimming operation.

(Light adjustment layer 70A)
In the configuration illustrated in FIG. 1 , the planar light source 200A further has a light adjustment layer 70A between the light guide layer 40 and the wavelength conversion layer 50 . Here, the light adjustment layer 70A is arranged on the upper surface 40a of the light guide layer 40 similarly to the colored layer 60A, and is located on the same plane as the colored layer 60A in cross-sectional view.

The light adjustment layer 70A has translucency and reflectivity. In other words, part of the light incident on the light adjustment layer 70A passes through the light adjustment layer 70A, and the other part is reflected by the light adjustment layer 70A. As schematically shown in FIG. 1, the light adjustment layers 70A are provided directly above the light emitting elements 20 so as to correspond to the light emitting elements 20 on the wiring substrate 10, respectively.

The light adjustment layer 70A, like the light reflecting member 30A, can be made of a resin material containing resin as a base material and particles of a reflecting material. The light adjustment layer 70A may further contain pigments, light absorbing materials, phosphors, and the like. The light adjustment layer 70A has a thickness in the range of, for example, 50 μm or more and 100 μm or less. The thickness of the light adjustment layer 70A in this embodiment can be, for example, about 50 μm.

By providing the light adjustment layer 70A above the emission surface of the light emitting element 20, light introduced from the light emitting element 20 travels through the interior of the light guide layer 40 toward the upper surface 40a of the light guide layer 40 in a direction substantially perpendicular to the emission surface. Light can be reflected by the light adjustment layer 70A. That is, light emitted from the upper surface 70a of the light adjustment layer 70A in a direction slightly inclined with respect to the optical axis L of the light emitting element 20 is reduced. In addition, the light introduced from the light emitting element 20 into the light guide layer 40 can be effectively diffused inside the light guide layer 40 by utilizing the reflection on the light adjustment layer 70A. By arranging the light adjustment layer 70A on the light guide layer 40 in this way, it is possible to suppress an extreme increase in the brightness of the region directly above the light emitting element 20 in the light emitting surface, It is possible to effectively spread the light in the horizontal direction inside. In other words, it is possible to suppress color unevenness on the light emitting surface while making the planar light source 200A thin.

The light adjustment layer 70A has such a shape and arrangement that it overlaps with the upper surface of the light emitting element 20 in plan view, so that the amount of light in the region directly above the light emitting element 20 in the light emitting surface of the planar light source 200A can be suppressed. In other words, it is possible to prevent the brightness of the area directly above the light emitting element 20 from becoming extremely high compared to other areas of the light emitting surface of the planar light source 200A.

The shape of the light adjustment layer 70A in plan view can be, for example, a rectangular shape as shown in FIG. The light adjustment layer 70A can have an area of 100% or more and 300% or less of the top surface of the light emitting element 20 . For example, when the upper surface 70a of the light adjustment layer 70A has a square shape, the length of one side can be about 0.5 mm. The center of the light adjustment layer 70A is preferably located on the optical axis L of the corresponding light emitting element 20. As shown in FIG.

The shape of the light adjustment layer 70A is not limited to a rectangular shape, and may be any shape that can cover the entire upper surface of the light emitting element 20 in a plan view. Other shapes such as a circular shape as shown in FIG. may be In any shape, the width of the light adjustment layer 70A in a cross-sectional view is typically larger than the width of the light emitting element 20 located directly below the light adjustment layer 70A.

The light adjustment layer 70A may have a shape that continuously covers the entire upper surface of the corresponding light emitting element 20, or a shape that partially covers the upper surface of the corresponding light emitting element 20 in plan view. may be Each of the light adjustment layers 70A provided directly above the light emitting elements 20 corresponding to the plurality of light emitting elements 20 may be provided on the upper surface 40a of the light guide layer 40 or the like in a light reflecting shape including a plurality of dots. . In this case, part of the upper surface 40a of the light guide layer 40 is exposed from the dots of the light adjustment layer.

FIG. 10 shows examples of light reflection patterns that can be applied to the light modulating layer. The light adjustment layer 70B shown in FIG. 10 has a light reflection pattern composed of a plurality of dots (second dots) arranged in a rectangular area. The center of the light reflection pattern is approximately aligned with the position of the optical axis L of the light emitting element 20 positioned directly below the light reflection pattern. A plurality of dots forming the light adjustment layer 70B may be arranged in a circular area in plan view.

In this example, the number density of these dots in the light reflection pattern (here, the set of second dots) of the light adjustment layer 70B increases from the outside toward the center of the light adjustment layer 70B. By adjusting the number density of the dots, it is possible to control the reflectance or transmittance of the light from the light emitting elements 20 positioned directly below the light adjustment layer 70B. By adjusting the number density of dots on the light guide layer 40 according to the distance from the optical axis L of the light emitting element 20, it is possible to change the transmittance according to the absolute value of the light distribution angle of the light emitting element 20. be. Here, the light distribution angle refers to the angle formed by the traveling direction of light rays emitted from the light emitting element 20 with respect to the optical axis L when the optical axis L of the light emitting element 20 is 0°.

The density of the particles of the reflector in the light adjusting layer may be changed according to the absolute value of the light distribution angle. For example, particles of the reflective material are densely distributed in a region where the absolute value of the light distribution angle is small compared to a region where the absolute value of the light distribution angle of the light emitting element 20 is large (that is, an angle range where the inclination from the optical axis L is large). Particles of a reflective material may be contained in the light adjustment layer so that Such distribution of the particles of the reflector can be obtained by controlling the film thickness of the light reflecting layer, for example, and the transmittance can be changed according to the absolute value of the light distribution angle. For example, the film thickness of the light adjustment layer may be gradually increased from the outside of the light adjustment layer toward the optical axis L. Alternatively, the same effect can be obtained by providing a plurality of apertures in the light adjustment layer so that the aperture ratio increases as the distance from the optical axis L increases.

(Light diffusion sheet 80)
As shown in FIG. 3 , the planar light source module 300 according to the embodiment of the present disclosure has a translucent laminate 90 above the wavelength conversion layer 50 . As described above, the light-transmitting laminate 90 includes the light diffusion sheet 80 and the prism sheet 85 . The light diffusion sheet 80 is positioned between the wavelength conversion layer 50 and the prism sheet 85 . The lower surface 80b of the light diffusion sheet 80 may be in direct contact with at least a portion of the upper surface 50a of the wavelength conversion layer 50, or may be entirely separated from the upper surface 50a of the wavelength conversion layer 50.

The light diffusion sheet 80 diffuses the light incident from the lower surface 80 b inside the light diffusion sheet 80 . The light diffusion sheet 80 is a sheet whose base material is a material that absorbs less visible light, such as polycarbonate resin, polystyrene resin, acrylic resin, or polyethylene resin. As the light diffusion sheet 80, an optical sheet commercially available under the name of diffuser film or the like may be used. The thickness of the light diffusion sheet 80 can be, for example, about 200 μm. The light diffusion sheet 80 may be a single layer, or may have a laminated structure including multiple sheets.

The structure for diffusing light is formed by providing unevenness on one or both of the upper surface 80a and the lower surface 80b of the light diffusion sheet 80, or by making the light diffusion sheet 80 contain a material having a refractive index different from that of the base material. It can be applied to the sheet 80. The light diffusion sheet 80 typically contains a light diffusion material. Particles (high refractive index fine particles) of a high refractive index material such as silicon oxide, zirconium oxide, and titanium oxide can be used as the light diffusing material. The surface of the light diffusion sheet 80 may be generally flat or may have fine irregularities.

(Prism array layers 81, 82)
In the configuration illustrated in FIG. 3 , a prism sheet 85 located above light diffusion sheet 80 includes prism array layers 81 and 82 . The lower surface 85 b of the prism sheet 85 may be in contact with the upper surface 80 a of the light diffusion sheet 80 or may be separated from the light diffusion sheet 80 .

Each of prism array layers 81 and 82 has a structure in which a plurality of prisms each extending in a predetermined direction are arranged. For example, the prism array layer 81 has a plurality of prisms each extending in the Y direction, and the prism array layer 82 has a plurality of prisms each extending in the X direction. Prism array layers 81 and 82 direct light incident from various directions in a direction (+Z direction in the figure) toward a liquid crystal panel (not shown in FIG. 3) or the like arranged facing planar light source module 300. refract. As a result, the light emitted from the upper surface 90a of the light-transmitting laminate 90, which is the light emitting surface of the planar light source module 300, mainly contains many components perpendicular to the upper surface 90a (parallel to the Z axis). The brightness when the module 300 is viewed from the front (Z direction) can be increased.

A commercially available optical member for backlight can be applied to the prism array layers 81 and 82 . As the prism array layer 81, for example, a prism film manufactured by 3M (model number: BEF4 DML) can be used, and as the prism array layer 82, a prism film manufactured by 3M (model number: TBEF2 DT LS) can be used. can be done.

The thicknesses of the prism array layers 81 and 82 can be, for example, approximately 0.07 mm and 0.09 mm, respectively. As a prism sheet, for example, 3M's Advanced Structured Optical Composite (ASOC) can be used. The thickness of such an optical sheet can be about half that of a simple lamination of two prism array layers. By employing such an optical sheet as a prism sheet, it is possible to make the planar light source module 300 thinner. Such a thin planar light source module 300 is particularly useful for applications such as smartphones.

The planar light source module 300 may further have a reflective polarizing layer (not shown) located above the prism array layer 82 . The reflective polarizing layer selectively transmits light with a polarization direction that matches the polarization direction of a polarizing plate arranged on the backlight side of the liquid crystal panel, for example, and transmits polarized light in a direction perpendicular to the polarization direction to the prism array layer 81 . , 82 side. A part of the polarized light that has returned from the reflective polarizing layer changes its polarization direction when reflected again by the prism array layers 81 and 82 or the light diffusion sheet 80, and becomes polarized light having the polarization direction of the polarizing plate of the liquid crystal display panel. The light is converted, enters the reflective polarizing layer again, and exits to the liquid crystal panel. As a result, the polarization direction of the light emitted from the planar light source 200A is aligned, and the light in the polarization direction effective for improving the brightness of the display surface of the liquid crystal panel can be obtained with high efficiency.

FIG. 11 schematically illustrates a planar light source according to another embodiment of the present disclosure; Compared with the planar light source 200A shown in FIG. 1, the planar light source 200B shown in FIG. 11 has a light reflecting member 30B instead of the light reflecting member 30A.

The planar light source 200B includes a light shielding structure provided between two adjacent segments each including one of the light emitting elements 20 . In the example shown in FIG. 11, a convex portion 30w is provided on the upper surface 30a of the light reflecting member 30B as such a light shielding structure. Here, the convex portion 30w is a triangular prism-shaped structure that extends along the Y direction in the drawing and is arranged between the first light emitting element 21 and the second light emitting element 22, and protrudes into the light guide layer 40. ing. In other words, the convex portion 30 w is covered with the light guide layer 40 .

FIG. 12 schematically shows an example of arrangement of the projections 30w. In order to avoid overcomplicating the drawing, here, an example of the arrangement of the convex portions 30w in the case where the planar light source 200B has an array of unit regions UR of 18 rows and 18 columns is shown. In the configuration illustrated in FIG. 12, the light shielding structure includes a plurality of linear projections 30w. Each of these convex portions 30w extends along the X direction or the Y direction between two unit regions adjacent to each other among the two-dimensionally arranged unit regions UR. It can be said that the light reflective member 30B has a grid-like structure on the upper surface 30a that protrudes toward the light guide layer 40. As shown in FIG. In the configuration illustrated in FIG. 12, the light shielding structure partially includes a portion positioned between the first light emitting element 21 and the second light emitting element 22 in plan view. The width of each projection 30w in plan view is, for example, about 220 μm.

As exemplified in FIG. 12, the plurality of convex portions 30w can be provided on the upper surface 30a of the light reflecting member 30B so as to surround each of the plurality of light emitting elements 20 in plan view. In this case, it can be said that the plurality of convex portions 30w define a unit region UR each including one of the plurality of light emitting elements 20. As shown in FIG. Here, the shape of the unit region UR in plan view is a rectangle.

The convex portion 30w can be formed of, for example, the same material as the material of the light reflecting member 30B. In this case, the convex portion 30w is formed integrally with the light reflecting member 30B and has light reflectivity. The convex portion 30w has a function of suppressing light emitted from the light emitting element 20 in one unit region UR of two unit regions UR adjacent to each other from entering the other unit region UR. By forming the convex portion 30w so as to surround the light emitting element 20 of each unit area UR, for example, a unit area UR in which the light emitting element 20 is in a lighting state to another unit area UR adjacent to the unit area UR. It can suppress the entry of light. That is, on the upper surface 50a of the wavelength conversion layer 50, the contrast ratio between the area immediately above the unit area UR with the light emitting element 20 in the ON state and the area above the unit area UR with the light emitting element 20 in the OFF state is can improve. Improving the contrast ratio between adjacent unit regions UR can be advantageous in applying local dimming.

The distance from the upper surface 30a of the light reflecting member 30B to the top of the convex portion 30w (the highest portion of the convex portion 30w) is For example, the range is 50% or more and 100% or less of the distance to. From the viewpoint of improving the contrast ratio between two unit regions UR adjacent to each other, it is advantageous to dispose the convex portion 30w having a shape whose top reaches the upper surface 40a of the light guide layer 40 on the planar light source.

In the example shown in FIG. 12, each of the plurality of protrusions 30w linearly extends continuously from one end to the other end of the light reflecting member 30B along the X direction or the Y direction. On the other hand, in the configuration illustrated in FIG. 13 , focusing on one unit region other than the unit region located on the outermost periphery among the plurality of unit regions UR arranged two-dimensionally, the light emission included in that unit region Four protrusions 30w are arranged so as to surround the element 20 . The unit region positioned at the outermost periphery in the two-dimensional arrangement of the unit regions UR may have the convex portion 30w outside the light emitting element 20 in plan view, and the region where the convex portion 30w is not formed is the outer edge. may have in

14 and 15 show other examples of the cross-sectional shape of the projection 30w. The cross-sectional shape of the protrusion 30w can be triangular as shown in FIG. 11, or can be trapezoidal as shown in FIG. The side surface of the convex portion 30w may be perpendicular to the upper surface 30a of the light reflecting member 30B. In other words, the cross-sectional shape of the protrusion 30w may be rectangular. The shape of one or more side surfaces defining the shape of the projection 30w is not limited to a flat shape, and may be a shape including a curved surface. For example, the cross-sectional shape of the protrusion 30w may be semicircular as shown in FIG. The cross-sectional shape of the protrusion 30w may be semi-elliptical, irregular, or the like. The cross-sectional shape of the surface of the convex portion 30w is not limited to a linear shape or an arc shape, and may be an arbitrary curved shape, or a shape including steps or bends.

The convex portion 30w may be part of the light reflecting member 30B. Alternatively, the convex portion 30w is provided in the planar light source by bonding a member made of the same material as the light reflecting member 30B or a material different from that of the light reflecting member 30B to the upper surface 30a of the light reflecting member 30B. may be When the convex portion 30w is provided on the planar light source by arranging a member different from the light reflecting member 30B on the upper surface 30a, there is a gap between the upper surface 30a of the light reflecting member 30B and the convex portion 30w in a cross-sectional view. may or may not have a clear boundary.

Instead of arranging the protrusions 30w, grooves such as V-grooves may be formed in one or both of the upper surface 40a and the lower surface 40b of the light guide layer 40. FIG. Alternatively, the light diffusing material may be dispersed in the light guide layer 40 so that the concentration in the region between the two adjacent light emitting elements 20 in plan view in the light guide layer 40 is relatively high. good. A light reflective material may be placed inside the groove provided in the light guide layer 40 . With such a configuration as well, it is possible to suppress light leakage between two unit regions UR that are in contact with each other, and an effect of improving the contrast ratio between the unit regions UR can be expected.

FIG. 16 shows a planar light source according to yet another embodiment of the present disclosure; 16, the planar light source 200C shown in FIG. 16 is a circuit element electrically connected to the wiring layer of the wiring board 10, and is a circuit different from the light emitting element 20. It also has an element 25 . In this example, the circuit element 25 is mounted on the wiring board 10 together with the light emitting element 20, and the circuit element 25 is entirely covered with the light reflecting member 30A. In other words, the planar light source 200C includes the circuit element 25 arranged on the wiring board 10 and entirely embedded inside the light reflecting member 30A.

The circuit element 25 can be, for example, a driver connected to two or more light emitting elements 20, or a protection element such as a Zener diode. When a protective element is arranged on the wiring board 10 as the circuit element 25, the circuit element 25 can be electrically connected in series or parallel to the light emitting element 20 of each unit region UR. In other words, the circuit element 25 can be mounted on the wiring board 10 for each unit region UR each including the light emitting element 20 .

By mounting not only the light emitting element 20 but also circuit elements such as a driver for driving a plurality of light emitting elements 20 on the wiring board 10, the structure of the external control circuit connected to the connector 18 can be simplified. Further, by embedding the circuit element 25 on the wiring board 10 in the light reflecting member 30A, absorption of the light emitted from the light emitting element 20 by the circuit element 25 can be avoided, and the circuit element 25 is mounted on the wiring board 10. It is possible to avoid a decrease in light utilization efficiency due to

FIG. 17 shows a planar light source according to yet another embodiment of the present disclosure; Compared with the planar light source 200A shown in FIG. 1, a planar light source 200D shown in FIG. and a sealing member 34 disposed within the bore 32 .

As will be described later, the light reflecting members 30A and 30B can be formed by curing a resin material applied on the wiring board 10. FIG. On the other hand, the light reflecting member 30C shown in FIG. 17 is obtained by placing a light reflecting resin sheet on the wiring board 10. In FIG. As a material of the light reflecting member 30C, a resin material in which a light reflecting filler is dispersed in a base material such as polyethylene terephthalate (PET) can be used. Titanium oxide particles, for example, may be dispersed as a light diffusing material in the base material of the light reflecting member 30C. Instead of dispersing the light diffusing material in the base material, a sheet of white polyethylene terephthalate containing many air bubbles may be obtained and this sheet may be used as the light reflecting member 30C. When the resin sheet is applied to the light reflecting member 30C, the upper surface 30a of the light reflecting member 30C is basically a flat surface.

The through holes 32 of the light reflecting member 30</b>C are provided at positions corresponding to the plurality of light emitting elements 20 on the wiring board 10 . When the circuit element 25 is arranged on the wiring board 10 as in the example shown in FIG.

As the material of the sealing member 34, a light-transmitting resin material similar to that of the light guide layer 40 can be applied, or a light-reflecting resin material similar to that of the light adjustment layer 70A can be applied. You can also A portion of the sealing member 34 may be located in the gap between the lower surface 20b of the light emitting element 20 and the upper surface 10a of the wiring substrate 10. As shown in FIG.

[2. Manufacturing Method of Planar Light Source 200A and Planar Light Source Module 300]
Next, an exemplary method of manufacturing a planar light source and a planar light source module according to embodiments of the present disclosure will be described with reference to the drawings. Below, the outline of the manufacturing method will be described by taking the planar light source 200A shown in FIG. 1 and the planar light source module 300 shown in FIG. 3 as examples.

First, a wiring board 10 (for example, FPC) and a plurality of light emitting elements 20 are prepared. Next, as shown in FIG. 18, the light emitting element 20 is mounted on the wiring substrate 10. Next, as shown in FIG. A resin member may be placed in the space between the lower surface 20b of the light emitting element 20 and the upper surface 10a of the wiring board 10 from the viewpoint of increasing the bonding strength of the light emitting element 20 to the wiring board 10 .

Next, the wiring board 10 with the light emitting elements 20 mounted thereon is placed in a mold, and a photocurable resin material is injected into the mold by potting, for example. By curing the resin material applied to the wiring board 10 by irradiating it with ultraviolet rays, the light reflecting member 30A covering the side surfaces 20c of the plurality of light emitting elements 20 can be formed as shown in FIG. Also, a thermosetting resin may be used instead of the photocurable resin material.

At this time, for example, one or more concave surfaces may be formed on the upper surface 30a of the light reflecting member 30A due to sink marks accompanying curing of the resin material. When the upper surface 30a includes a concave surface, the number of reflections between the upper surface 30a of the light reflecting member 30A and the upper surface 40a of the light guide layer 40 increases, which may improve the light extraction efficiency. The concave surface of the upper surface 30a of the light reflecting member 30A can be formed in a lattice shape on the upper surface 30a so as to surround the light emitting element 20 in plan view.

The resin material may be applied so as to cover the upper surface 20a of the light emitting element 20 on the wiring board 10. FIG. In this case, after the resin material applied on the wiring board 10 is cured, part of the cured resin material may be removed by grinding from the upper surface 20a side. By grinding the resin material after curing, the top surface 20a of the light-emitting element 20 can be exposed from the light-reflecting member 30A, and the top surface 30a of the light-reflecting member 30A can be aligned with the top surface 20a of the light-emitting element 20.

Next, a translucent resin material is applied to the upper surface 30a of the light reflecting member 30A and the upper surface 20a of the light emitting element 20 so as to cover the light reflecting member 30A and the light emitting element 20, and cured. By curing the resin material, as shown in FIG. 20, the light guide layer 40 that collectively covers the light emitting elements 20 over a plurality of unit regions can be formed. At this time, one or more concave surfaces may be formed on the upper surface 40a of the light guide layer 40 due to sink marks accompanying curing of the resin material. When the upper surface 40a includes a concave surface, the number of reflections between the lower surface 50b of the wavelength conversion layer 50 and the upper surface 40a of the light guide layer 40, which will be described later, increases, which may improve the light extraction efficiency.

Next, the colored layer 60A is arranged in a region of the upper surface 40a of the light guide layer 40 that does not overlap the light emitting element 20 in plan view. For example, a resin material containing a pigment is prepared, silk screen printing, inkjet printing, or the like is used to apply the resin material onto a predetermined region of the upper surface 40a of the light guide layer 40, and the resin material is cured. As a result, a colored layer 60A can be obtained on the upper surface 40a of the light guide layer 40, as shown in FIG.

Similarly, the light adjustment layer 70A may be arranged in a predetermined region of the upper surface 40a of the light guide layer 40. FIG. A resin material containing particles of a reflective material is applied to a predetermined region of the upper surface 40a of the light guide layer 40 by a printing method or the like, and then the resin material is cured to form the light adjustment layer 70A having a desired shape and arrangement. can be obtained (see FIG. 21). At this time, it is preferable to dispose the light adjustment layer 70A so that at least part of the light adjustment layer 70A overlaps the optical axis L of the light emitting element 20 in plan view. The order of execution of the step of forming the colored layer 60A and the step of forming the light adjustment layer 70A is arbitrary, and they may be executed in parallel.

After that, the wavelength conversion layer 50 is arranged above the colored layer 60A and the light adjustment layer 70A. The wavelength conversion layer 50 can be supported above the coloring layer 60A and the light adjustment layer 70A by a frame arranged on the wiring board 10, a housing that accommodates the wiring board 10, or the like. 200 A of planar light sources shown in FIG. 1 are obtained through said process.

Note that the colored layer 60A and/or the light adjustment layer 70A may be formed on a portion other than the upper surface 40a of the light guide layer 40, for example, on the lower surface 50b of the wavelength conversion layer 50. FIG. For example, by forming the colored layer 60A and the light adjustment layer 70A on a resin sheet containing phosphor particles, etc., and disposing the resin sheet above the upper surface 40a of the light guide layer 40, the light shown in FIG. It is possible to obtain a structure similar to that of the planar light source 200A. However, by arranging the colored layer 60A and/or the light adjustment layer 70A on the upper surface 40a of the light guide layer 40, there is an advantage that the alignment accuracy with respect to the optical axis L of the light emitting element 20 can be easily secured.

By mounting the circuit element 25 on the wiring board 10 before forming the light reflecting member 30A, a planar light source 200C illustrated in FIG. 16 is obtained. Further, after the material of the light reflecting member 30A is cured, the material of the light reflecting member 30A is further applied, for example, linearly to the surface of the cured material using a dispenser or the like, and then cured, as illustrated in FIG. 11 and the like. , the light reflecting member 30B having the convex portion 30w can be formed. Alternatively, the projections 30w may be arranged on the upper surface 30a of the light reflective member 30A by joining a light reflective resin member formed in a grid pattern, for example, onto the upper surface 30a of the light reflective member 30A.

Instead of forming the light reflecting member 30A by curing a resin material applied on the wiring board 10, the surface having the light reflecting member 30C is formed by placing a resin sheet or the like on the wiring board 10. A shaped light source 200D (see FIG. 17) may be obtained. For example, after mounting the light emitting elements 20 on the wiring board 10, as illustrated in FIG. may be arranged on the wiring substrate 10 by Thereby, the light reflecting member 30</b>C having the through holes 32 at positions corresponding to the plurality of light emitting elements 20 can be arranged on the wiring substrate 10 .

A resin sheet having a plurality of through holes 32 can be purchased and prepared. Alternatively, a resin sheet for forming the light reflecting member 30C may be prepared by forming the through holes 32 after manufacturing or purchasing a resin sheet. The method of forming the through holes 32 is not particularly limited. For example, by forming a plurality of through holes 32 in a resin sheet by punching, a light reflecting member 30C having through holes 32 provided at desired positions can be obtained. When the circuit element 25 is arranged on the wiring board 10 , the through hole 32 may be formed also at the position corresponding to the circuit element 25 .

If necessary, as shown in FIG. 23, the inside of each through-hole 32 is filled with a resin material. After that, the sealing member 34 can be formed in the through hole 32 by curing the resin material inside the through hole 32 . Here, the upper surface 34a of the sealing member 34 and the upper surface 20a of the light emitting element 20 are on the same plane. When forming the light-reflecting member covering the side surface of each light-emitting element 20 on the wiring board 10 using a resin sheet, the entire light-reflecting member on the wiring board 10 is covered with a resin sheet and a resin sheet. Forming from the resin material arranged in the provided through hole 32 is not essential. A part of the light reflecting member 30A or 30B described above may be replaced with the resin sheet and the sealing member 34 inside the through hole 32 .

When the light reflecting member 30C is formed from a resin sheet, the upper surface 30a of the light reflecting member 30C may be a flat surface without recesses. 14 and 15, by linearly applying a resin material onto a resin sheet and curing the resin material, or by joining a linear or grid-shaped resin member to the resin sheet. In addition, it is possible to form a convex portion 30w having a shape surrounding the light emitting element 20 in plan view on the upper surface 30a side of the light reflecting member 30C.

After obtaining the planar light source 200A, for example, a frame having a shape surrounding the planar light source 200A is arranged on the wiring substrate 10, and the translucent laminate 90 is positioned above the wavelength conversion layer 50 of the planar light source 200A. is fixed to the frame, the planar light source module 300A shown in FIG. 3 is obtained. Tape attachment, laser welding, or the like can be applied to fix the translucent laminate 90 to the frame. A planar light source module may be obtained by obtaining one of the planar light sources 200B to 200D instead of the planar light source 200A and disposing the translucent laminate 90 above the planar light source.

The light-emitting device and planar light source of the present disclosure can be used as backlight sources for liquid crystal displays, various lighting fixtures, and the like.

10 Wiring board 20-22 Light emitting element 25 Circuit element 30A-30C Light reflecting member 34 Sealing member 40 Light guide layer 50 Wavelength conversion layer 60A, 60B Colored layer 70A, 70B Light adjustment layer 80 Light diffusion sheet 85 Prism sheet 90 Transparent Optical laminate 200A to 200D Planar light source 300 Planar light source module

Claims (13)

a wiring board;
at least one light emitting element arranged on the wiring substrate;
a light reflective member disposed on the wiring board and covering a side surface of the light emitting element;
a light guide layer disposed on the light emitting element and the light reflecting member;
a wavelength conversion layer disposed above the light guide layer;
A surface provided with a colored layer positioned between the light guide layer and the wavelength conversion layer and positioned around the light emitting element in plan view, the colored layer absorbing light having a specific wavelength. shaped light source. The light emitting element emits blue light,
2. The planar light source according to claim 1, wherein the light having the specific wavelength is blue light emitted from the light emitting element. 3. The planar light source according to claim 2, wherein said colored layer contains a blue pigment. 4. The planar light source according to claim 1, wherein said light guide layer contains a light diffusing material. The colored layer includes a plurality of first dots arranged around the light emitting element in plan view,
5. The planar light source according to claim 1, wherein an area ratio of said plurality of first dots per unit area increases with increasing distance from said light emitting element. 6. The planar light source according to claim 5, wherein said plurality of first dots are arranged concentrically around said light emitting element in plan view. 7. The planar light source according to any one of claims 1 to 6, further comprising a light adjustment layer located directly above the light emitting element and between the light guide layer and the wavelength conversion layer. The light adjustment layer includes a set of a plurality of second dots arranged in a circular or rectangular area in plan view,
8. The planar light source according to claim 7, wherein the number density of the plurality of second dots increases toward the center of the light emitting element. the at least one light emitting element is a plurality of light emitting elements including a first light emitting element and a second light emitting element;
9. The planar light source according to any one of claims 1 to 8, further comprising a light shielding structure including a portion positioned between the first light emitting element and the second light emitting element in plan view. the light shielding structure is a convex portion located on the upper surface of the light reflecting member and protruding into the light guide layer;
10. The planar light source according to claim 9, wherein the convex portion has a shape surrounding each of the first light emitting element and the second light emitting element in plan view. 11. The planar light source according to claim 10, wherein said convex portion is formed integrally with said light reflecting member. further comprising at least one driver for driving the plurality of light emitting elements;
12. The planar light source according to claim 9, wherein said at least one driver is arranged on said wiring board and covered with said light reflecting member. a planar light source according to any one of claims 1 to 12;
a light diffusion sheet disposed above the wavelength conversion layer;
and a prism sheet disposed above the light diffusion sheet.

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