CN110764308B

CN110764308B - Backlight source assembly and backlight module

Info

Publication number: CN110764308B
Application number: CN201910987752.4A
Authority: CN
Inventors: 陈建民
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2019-03-06
Filing date: 2019-10-17
Publication date: 2023-04-11
Anticipated expiration: 2039-10-17
Also published as: TW202033911A; TWI671491B; CN110764308A

Abstract

A backlight source assembly comprises a substrate, a light emitting element, a lens and at least one light absorbing element. The light emitting element is disposed on the substrate to emit light thereon. The lens is arranged on the substrate and covers the light-emitting element, and is provided with a main shaft, an incident light side and an emergent light side, wherein the main shaft passes through the centers of the incident light side and the emergent light side, the main shaft passes through the light-emitting element, and the incident light side faces the substrate to receive light rays emitted by the light-emitting element. The light absorbing element is made of light absorbing material at least on the surface part, the light absorbing element is arranged around the light emitting element in a radiation symmetry mode according to the main axis, and the light absorbing element is located in the projection range of the lens on the substrate.

Description

Backlight source assembly and backlight module

Technical Field

The present invention relates to a direct type backlight design for a liquid crystal panel, and more particularly, to a backlight assembly and a backlight module.

Background

In a direct type backlight module for a liquid crystal panel backlight, light Emitting Diodes (LEDs) are used as point light sources to arrange and arrange projected light on a reflector. The point light source is further provided with an optical lens to change the light path and convert the point light source into a uniform backlight. However, the lens arrangement often causes an aperture or dark line outside or above the lens, resulting in uneven brightness.

The existing improvement method is to print black dots on the substrate under the lens or change the lens design to improve the aperture or dark lines. There is still room for improvement in the effect of printing black dots or altering the lens design.

Disclosure of Invention

In the direct-type backlight module, an aperture or dark fringes are formed outside or above the lens, which causes brightness unevenness.

In view of the above problems, the present invention provides a backlight assembly capable of effectively improving an aperture or dark fringes.

At least one embodiment of the present invention provides a backlight assembly, which includes a substrate, a light emitting device, a lens, and at least one light emitting device.

The light emitting element is disposed on the substrate to emit light thereon. The lens covers the light-emitting element, and is provided with a main shaft, an incident light side and an emergent light side, wherein the main shaft passes through the centers of the incident light side and the emergent light side, the main shaft passes through the light-emitting element, and the incident light side faces the substrate to receive light rays emitted by the light-emitting element. The light absorption element is at least a surface part of light absorption material, the light absorption element is arranged around the light emitting element in a radiation symmetry mode according to the main axis, and the light absorption element is located in the projection range of the lens on the substrate.

In at least one embodiment of the present invention, the light incident side has a recessed area, the main axis passes through the recessed area, and the projection of the light emitting device on the substrate is located within the projection range of the recessed area on the substrate.

In at least one embodiment of the present invention, the light absorbing element is not located in the projection range of the concave region on the substrate.

In at least one embodiment of the present invention, the lens has a plurality of supporting legs protruding from the light incident side and fixed on the substrate.

In at least one embodiment of the present invention, the light absorbing element does not overlap the supporting legs.

In at least one embodiment of the present invention, the light absorbing element is a coating mark coated on the substrate with the light absorbing coating.

In at least one embodiment of the present invention, the light absorbing element is a ring.

In at least one embodiment of the present invention, the ring is a solid ring or a dashed ring.

In at least one embodiment of the present invention, the width of the ring is greater than 0.05mm and less than 0.5mm, and the radius of the ring is required to be less than or equal to the radius of the lens.

In at least one embodiment of the present invention, the radius of the ring is not less than 0.5 times the radius of the lens.

In at least one embodiment of the present invention, the backlight assembly has a plurality of light absorbing elements, and the radiation is symmetrically disposed and uniformly distributed around the light emitting elements.

In at least one embodiment of the present invention, each light absorbing element is linear and extends outward along an extending direction with the main axis as a center.

In at least one embodiment of the present invention, the lens has a lens radius relative to the principal axis, and the length of each light absorbing element in the extending direction is smaller than the lens radius and larger than 1mm.

In at least one embodiment of the present invention, the width of the light absorbing element is greater than 1mm and less than 0.15 times the circumference of the lens in a tangential direction perpendicular to the extending direction.

In at least one embodiment of the present invention, the surface of the substrate is coated with a high-reflectivity material.

In at least one embodiment of the present invention, each light absorbing element is a sector, an isosceles triangle, an arc, or a crescent.

In at least one embodiment of the present invention, the light absorbing material of the light absorbing element is a photoluminescent material.

In at least one embodiment of the present invention, the backlight assembly further includes a back plate, the substrate is disposed on the back plate; and a reflector plate arranged on the substrate and having at least one opening for accommodating the light-emitting element.

In another embodiment of the present invention, a backlight module includes a substrate, a plurality of light emitting elements, a plurality of lenses, and a plurality of light absorbing elements.

The plurality of light emitting elements are arranged on the substrate in an array form so as to emit light on the substrate. Each lens corresponds to one of the light-emitting elements and covers the corresponding light-emitting element; each lens is provided with a main shaft, an incident light side and an emergent light side, the main shaft passes through the centers of the incident light side and the emergent light side, the main shaft passes through the light-emitting element, and the incident light side faces the substrate so as to receive light rays emitted by the light-emitting element. At least part of the surface of each light absorption element is made of light absorption materials, each light emitting element corresponds to one group of light absorption elements, each group of light absorption elements is arranged around the corresponding light emitting element in a radiation symmetry mode according to the main axis, and the light absorption elements are located in the projection range of the corresponding lens on the substrate.

In at least one embodiment of the present invention, the light absorbing elements between two adjacent light absorbing elements are disposed in a staggered manner.

In at least one embodiment of the present invention, an imaginary line segment is defined between two adjacent light emitting elements, and no more than one light absorbing element is disposed on the imaginary line segment.

In at least one embodiment of the present invention, the backlight module further includes a back plate, the substrate is disposed on the reflective sheet; and a reflector plate arranged on the substrate and having multiple openings for accommodating the light emitting elements.

The invention is arranged around the light-emitting element symmetrically through the radiation of the light-absorbing element, and can improve the aperture or dark lines. Meanwhile, the light emitting elements arranged symmetrically by radiation have relatively few parameters to be considered, mainly the distance and length relative to the principal axis and the width relative to the tangential direction, which is more favorable for finding out the optimal configuration of the light absorbing element.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIG. 1 is a cross-sectional view of a backlight assembly according to a first embodiment of the invention.

Fig. 2 is a top view of a backlight assembly according to a first embodiment of the invention.

Fig. 3 is a top view of a partial element in a first embodiment of the invention.

FIG. 4 is a top view of the light emitting element, the light absorbing element and the lens showing the relative size relationship according to the first embodiment of the present invention.

FIGS. 5 to 8 are top views of the light emitting device, the light absorbing device and the lens according to the first embodiment of the present invention, which illustrate different types of light absorbing devices.

FIGS. 9 and 10 are top views of the light emitting device, the light absorbing device and the lens according to the first embodiment of the invention, showing the light absorbing devices in different ring shapes.

FIG. 11 is a cross-sectional view of a backlight assembly according to a second embodiment of the present invention.

FIG. 12 is a top view of a backlight module according to a third embodiment of the present invention.

FIGS. 13 and 14 are top views of light emitting elements, light absorbing elements and lenses according to a third embodiment of the invention, showing the arrangement of the light absorbing elements between adjacent light emitting elements.

Wherein, the reference numbers:

10. backlight module of backlight source assembly 100

110. Substrate 120 light emitting element

130. Light incident side of lens 132

134. Light exit side 136 recessed area

138. Light absorbing element of the leg 140

150. Back plate 160 reflector plate

162. Imaginary line segment of the opening B

L length R lens radius

C the direction of extension of the dotted line E

W width X main shaft

Detailed Description

The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:

in the drawings, the widths of some of the elements, regions, etc. are exaggerated for clarity. Like reference numerals refer to like elements throughout the specification. It will be understood that when an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present.

It will be understood that, although the terms "first," "second," "third," etc. may be used throughout the description to describe various elements, components, regions or sections. These elements, components, regions, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, or section from another element, component, region, layer, or section. Thus, a "first element," "component," "region" or "section" discussed below could be termed a second element, component, region or section without departing from the teachings herein.

In addition, relative terms such as "lower" or "floor" and "upper" or "top" may be used herein to describe one element's relationship to another element as illustrated. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. Thus, the exemplary term "lower" can encompass both an orientation of "lower" and "upper," depending on the particular orientation of the figure.

As shown in fig. 1, fig. 2 and fig. 3, a backlight assembly 10 according to a first embodiment of the present disclosure includes a substrate 110, a light emitting element 120, a lens 130 and one or more light absorbing elements 140.

As shown in fig. 1, 2 and 3. The portion shown by the dotted line in fig. 3 is a lens 130, which is expected to be disposed on the substrate 110 to cover the light emitting element 120 and the light absorbing element 140. As shown, the substrate 110 serves as a load bearing base and provides the necessary electrical connections. In one embodiment, the substrate 110 is a printed circuit board having a printed copper foil circuit for supplying power to the light emitting device 120. The power supply means is not limited to the printed copper foil circuit, and may be other electrical connection means, that is, the substrate 110 is not limited to the printed circuit board, and may be a general board.

As shown in fig. 1, 2 and 3, the light emitting element 120 may be, but not limited to, a Light Emitting Diode (LED) chip, and is used as a point light source. The light emitting element 120 is disposed on the substrate 110 to emit light on the substrate 110. The lens 130 is disposed on the substrate 110 and covers the light emitting element 120.

As shown in fig. 1, the lens 130 has a main axis X, a light-entering side 132 and a light-exiting side 134. The major axis X passes through the centers of the light entrance side 132 and the light exit side 134, and the major axis X passes through the light emitting element 120. The light incident side 132 faces the substrate 110 for receiving the light emitted from the light emitting device 120 and refracting the light once. The light rays are refracted twice by the light exit side 134, exit the lens 130, and travel directions converge toward the principal axis X.

As shown in fig. 1, 2 and 3, the light incident side 132 has a recessed area 136 thereon, and the major axis X passes through the recessed area 136. The projection of the light emitting device 120 on the substrate 110 is located within the projection range of the concave region 136 on the substrate 110. The concave region 136 forms a concave primary curved surface for primary refraction. In addition, the lens 130 further has a plurality of supporting legs 138 protruding from the light incident side 132 and disposed in a radial symmetry (in a radial symmetry manner) according to the main axis X for being fixed to the substrate 10. Taking the lens 130 with three support legs 138 as an example, each support leg 138 has an equal distance from the main axis X, and an extension line is defined between each support leg 138 and the main axis X, and the included angles between adjacent extension lines are equal (the included angle is 120 degrees).

As shown in fig. 1, 2 and 3, the light absorbing element 140 is made of a light absorbing material at least on a surface portion, so that the surface of the light absorbing element 140 is black or other darker colors. The light absorbing element 140 is disposed around the light emitting element 120 in a radiation symmetry manner based on the main axis X, and absorbs light moderately to improve the aperture or dark fringe at the edge or outside of the lens 130.

It should be noted that the thickness of the light absorbing element 140 shown in fig. 1 is only an example, and is not intended to limit the ratio of the thickness. In one embodiment, the light absorbing element 140 is a coating mark coated on the substrate 110 with a light absorbing coating, and the thickness of the coating mark is relatively smaller than that of other elements. The coating is not limited to the application by pen or printing, but also includes screen printing, ink-jet printing, and transfer printing. Where the backlight assembly 10 has only one light absorbing element 140, the radiation symmetry is defined as a closed pattern, such as a ring, formed by the light absorbing element 140 being a solid line. In the case of the backlight assembly 10 having a plurality of light absorbing elements 140, the light absorbing elements 140 are disposed symmetrically so as to be uniformly distributed around the light emitting elements 120. In addition, in order to avoid light absorption at other parts of the substrate 110, the surface of the substrate 110 has a higher reflection coefficient (higher than the reflection coefficient of the light absorbing element 140), for example, the surface of the substrate 110 is coated with a white or other light-colored high reflection coefficient material, so that the surface of the substrate 110 appears white.

As shown in fig. 3, in principle, the light absorbing element 140 is located within the projection range of the lens 130 on the substrate 110, and is not located within the projection range of the concave region 136 of the lens 130 on the substrate 110. In addition, the light absorbing element 140 does not overlap the supporting legs 138 of the lens 130. Taking fig. 3 as an example, the backlight assembly 10 has three light absorbing elements 140, and the lens 130 has three supporting legs 138. When viewed from above the substrate 110, each light absorbing element 140 passes between adjacent support legs 138 without overlapping the support legs 138. Meanwhile, the light absorbing elements 140 extend radially from the outside of the concave region 136 toward the edge of the lens 130, but not beyond the edge of the lens 130.

Taking fig. 3 and 4 as an example, the light absorbing element 140 is a linear type, such as a black line printed on the substrate 110, extending outward along an extending direction E with the main axis X as a center, and the projection of the lens 130 on the substrate 110 is substantially circular, so that the lens 130 has a lens radius R relative to the main axis X. The length L of the light absorbing element 140, in the direction of extension E, is less than the lens radius R and greater than 1mm. In a tangential direction perpendicular to the extending direction E, the width W of the light absorbing element 140 is greater than 1mm and less than 0.15 times the circumference of the lens 130.

As shown in fig. 5 to 8, the line-type (black line-shaped) light absorbing element 140 is merely an example, and the light absorbing element 140 may be in other types. The light absorbing element 140 shown in fig. 5 has a fan shape with its tip pointing towards the main axis X, and the fan shape is radiatively symmetrically arranged around the light emitting element 120. The light absorbing element 140 shown in fig. 6 is an isosceles triangle, the vertex angle of the isosceles triangle points to the main axis X, and the isosceles triangle is disposed around the light emitting element 120 in a radial symmetry. The light absorbing element 140 shown in fig. 7 and 8 has an arc shape or a crescent shape, an extension line of the equivalent radius passes through the main axis X, and the arc shape or the crescent shape is radially and symmetrically disposed around the light emitting element 120.

In principle, the shape of the light absorbing elements 140 is not limited, and it is only necessary that the light absorbing elements 140 have the same shape and are disposed around the light emitting elements 120 in a radiation symmetric manner such that the light absorbing elements 140 surround the light emitting elements 120 uniformly. In this way, the light absorption effect of the light absorption elements 140 is more uniform, and the light absorption effect does not have a specific directionality.

As shown in fig. 9 and 10, if the number of arcs in fig. 7 is increased and the arc length is decreased, a dashed ring is formed. The dashed ring can be regarded as a single light-absorbing element 140, or a set of light-absorbing elements 140. If the arcs in FIG. 7 are further extended to interconnect the arcs, a solid ring is formed as a single light absorbing element 140. In principle, the ring of fig. 9 and 10 does not overlap the support legs 138 of the lens 130, and the center of the ring is located on the main axis X. The width of the ring is greater than 0.05mm and less than 0.5mm, and the radius of the ring is less than or equal to the radius R of the lens (i.e. the projection of the light emitting device 120 on the substrate 110 is within the projection range of the lens 130 on the substrate 110), but not less than 0.5 times the radius R of the lens, so as to ensure that the ring as the light absorbing element 140 can absorb light effectively.

In general, the greater the width of the ring, the smaller the radius of the ring. With the solid line ring of fig. 10, when the ring width is 0.35mm, the radius of the ring has better light-equalizing effect when the radius of the ring is equal to 0.625 times the lens radius R. When the ring width is reduced to 0.15mm, the ring radius needs to be increased to 0.75 times the lens radius R. However, when the solid line ring is replaced with the dotted line ring, the radius of the ring needs to be increased, for example, the dotted line ring having a ring width of 0.2mm, and the radius of the ring needs to be increased to 0.8 times the radius R of the lens.

The light absorbing material of the light absorbing element 140 is not necessarily black, which absorbs light in the full spectrum, but may be another color that absorbs light for a specific spectral range. For example, due to the difference in refractive index, a yellow ring may occur around the light emitting device due to the color unevenness of the light source. In this case, the light absorbing material of the light absorbing element 140 may be changed to blue, for example, a black straight line, a black dotted line ring or a black solid line ring may be changed to a blue straight line, a blue dotted line ring or a blue solid line ring, so that the yellow ring generated by the color unevenness of the light source can be improved by suppressing the color light other than blue light.

The light absorbing material of the light absorbing element 140 is not necessarily a material that absorbs light, and may be a material that is excited to emit light in other frequency spectrums after absorption. For example, in one embodiment, the light absorbing material of the light absorbing element 140 is a photoluminescent material, such as a quantum dot material (quantum dot material), a phosphorescent material (phosphor material) or a fluorescent material (fluorescent material), which can be excited by blue light to generate white light. In this case, the light emitting element 120 can improve the halo with uneven color brightness by only selecting a blue light source capable of emitting monochromatic light (blue light).

Referring to fig. 1, the backlight assembly 10 further includes a back plate 150 and a reflective sheet 160. The back plate 150 is used as a part of a display device on which the substrate 110 is disposed, so that the backlight assembly 10 is combined with the substrate 110 to form a backlight module 100. The backlight module 100 may further combine a display medium (such as a liquid crystal panel), a driving circuit, and a front frame to form a display device. The reflective sheet 160 is disposed on the substrate 110, and the reflective sheet 160 has at least one opening 162 for accommodating the light emitting device 120. In the first embodiment, the radius of the opening 162 is larger than the lens radius R. Therefore, the supporting legs 138 of the lens 130 are fixed on the substrate 110, and the light absorbing element 140 is also disposed on the substrate 110. In this case, at least a portion of the surface of the substrate 110 corresponding to the opening 162 must be coated with a white paint or a reflective material to maintain a uniform reflection effect on the reflective sheet 160.

Referring to fig. 11, in a second embodiment of the disclosed light emitting source assembly, the radius of the opening 162 is smaller than the radius of the lens 130, and only the light emitting device 120 can be substantially accommodated. At this time, the supporting legs 138 of the lens 130 are fixed to the reflecting sheet 160 or the substrate 10, and the light absorbing element 140 is also disposed on the reflecting sheet 160. In this embodiment, the reflective sheet 160 can be regarded as a portion of the substrate 10, that is, the substrate 10 includes a base layer and a reflective layer, and the reflective layer is provided with an opening 162 to expose a part of the base layer.

Referring to fig. 12, a backlight module 100 according to a third embodiment of the present invention includes a substrate 110, a plurality of light emitting elements 120, a plurality of lenses 130, and a plurality of light absorbing elements 140. The technical details of the substrate 110, the light emitting elements 120, the lenses 130, and the light absorbing elements 140 are substantially the same as those of the previous embodiments, and are not repeated herein.

As shown in fig. 12, the light emitting elements 120 are disposed on the substrate 110 in an array, especially a two-dimensional rectangular array. Each lens 130 corresponds to a light emitting device 120 and covers the corresponding light emitting device 120.

As shown in fig. 12, each light emitting device 120 corresponds to one group of light absorbing devices 140, the number of the light absorbing devices 140 in each group is the same, and the types of the light emitting devices 120 are the same. Each light emitting element 120 is made of light absorbing material at least on the surface portion, so that the surface of the light absorbing element 140 is black or other darker colors. The light absorbing element 140 is disposed around the light emitting element 120 in a radiation symmetry manner based on the main axis X. In order to simplify the drawing, the lens 130 in fig. 12 has been simplified, and the details of the lens 130 refer to the first or second embodiment.

As shown in fig. 12, 13 and 14, in order to avoid the concentrated addition of the light absorption effects of the light absorption elements 140, the light absorption elements 140 between two adjacent groups of light absorption elements 140 are disposed in a staggered manner, so as to avoid the two light absorption elements 140 being directly adjacent to each other and forming a concentrated light absorption block between the two light emitting elements 120. That is, an imaginary line segment B is defined between two adjacent light emitting elements 120, and no more than one light absorbing element 140 is located on the imaginary line segment B. As shown in fig. 13, no light emitting element 120 is disposed on the imaginary line segment B, and as shown in fig. 14, only one light emitting element 120 is disposed on the imaginary line segment B. This imaginary line segment B may connect two adjacent light emitting elements 120 in the transverse direction, or may connect two adjacent light emitting elements 120 in the longitudinal direction. This prevents a concentrated light absorption effect from being formed around the midpoint of the imaginary line segment B, for example, in the region where the dotted line C passes.

Referring to fig. 1 and 12, the backlight source assembly 10 of fig. 1, 2 and 3 is expanded into an array, which is the backlight module 100 of fig. 12. That is, the backlight module 100 further includes a back plate 150 and a reflective sheet 160. The back plate 150 is used as a part of a display device on which the substrate 110 is disposed, so that the backlight assembly 10 is combined with the substrate 110 to form a backlight module 100. The backlight module 100 further combines a display medium (e.g., a liquid crystal panel), a driving circuit, and a front frame to form a display device. As shown in the foregoing embodiments, the reflective sheet 160 is disposed on the substrate 110, and the reflective sheet 160 has a plurality of openings 162 for accommodating the light emitting devices 120. The radius of the opening 162 may be greater or less than the lens radius R. According to the relationship between the opening 162 and the lens radius R, it can be determined that the supporting legs 138 and the light absorbing element 140 are disposed on the substrate 110 or the reflective sheet 160.

The light absorbing element 140 is disposed around the light emitting element 120 in a radiation symmetrical manner, so that light can be absorbed appropriately to improve aperture or dark fringe. Meanwhile, the light emitting elements 120 arranged symmetrically in the radiation mode have relatively few parameters to be considered, mainly the distance and length relative to the principal axis and the width relative to the tangential direction, which is favorable for finding out the optimal configuration of the light absorbing element 140.

The present invention is capable of other embodiments, and various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A backlight module, comprising:

a substrate;

a plurality of light emitting elements arranged on the substrate in an array form to emit light on the substrate;

a plurality of lenses, each lens corresponding to one of the light-emitting elements and covering the corresponding light-emitting element; each lens is provided with a main shaft, an incident light side and an emergent light side, the main shaft passes through the centers of the incident light side and the emergent light side, the main shaft passes through the light-emitting element, and the incident light side faces the substrate to receive light rays emitted by the light-emitting element; and

a plurality of groups of light absorption elements, at least part of the surface of each light absorption element is made of light absorption materials, each light emitting element corresponds to one group of light absorption elements, each group of light absorption elements is arranged around the corresponding light emitting element in a radiation symmetry mode by taking the main axis as a basis, and the light absorption elements are positioned in the projection range of the corresponding lens on the substrate;

and the light absorbing elements are arranged between two adjacent groups of the light absorbing elements in a staggered manner.

2. The backlight module of claim 1, wherein the light incident side has a recessed area, the main axis passes through the recessed area, and a projection of the light emitting device on the substrate is located within a projection range of the recessed area on the substrate.

3. The backlight module of claim 2, wherein the light absorbing element is not located within a projection range of the concave region on the substrate.

4. The backlight module of claim 1, wherein the lens has a plurality of supporting legs protruding from the light incident side and fixed to the substrate.

5. The backlight module of claim 4, wherein the light absorbing element does not overlap the supporting legs.

6. The backlight module of claim 1, wherein the light absorbing element is a coating mark coated on the substrate with a light absorbing coating.

7. The backlight module of claim 1, wherein each of the light absorbing elements is linear, fan-shaped, isosceles triangular, arc-shaped, or crescent-shaped.

8. The backlight module of claim 1, wherein the light absorbing material of the light absorbing element is a photoluminescent material.

9. The backlight module of claim 1, wherein the lens has a lens radius with respect to the principal axis, and the length of each light absorbing element is less than the lens radius and greater than 1 mm; the width of the light absorbing element is greater than 1mm and less than 0.15 times the circumference of the lens.

10. The backlight module of claim 1, wherein an imaginary line segment is defined between two adjacent light emitting elements, and no more than one light absorbing element is located on the imaginary line segment.

11. The backlight module of claim 1, further comprising:

a back plate, on which the substrate is arranged; and

the reflector plate is arranged on the substrate and provided with a plurality of openings for accommodating the light-emitting elements.