Planar light source

Abstract

The objective of this invention is to provide a thin-film planar light source. The planar light source includes: a support member; a light guide member disposed on the support member and having a light source placement portion; and a light source disposed on the support member and on the light source placement portion of the light guide member. The support member includes: an insulating substrate having a first surface on the light source side and a second surface opposite to the first surface; a first conductive layer disposed on the first surface of the insulating substrate and electrically connected to the light source; an adhesive layer disposed on the first surface of the insulating substrate and on the first conductive layer, in contact with the first surface of the insulating substrate and the first conductive layer; and a light-reflective sheet disposed on the adhesive layer.

Description

Technical Field

[0001] The present invention relates to a planar light source. Prior Technology

[0002] Light-emitting modules that combine light-emitting elements such as light-emitting diodes with light guide plates are widely used in surface light sources such as backlights for liquid crystal displays. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-13714 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] The purpose of this invention is to provide a thin, planar light source. [Technical means to solve the problem]

[0006] According to one embodiment of the present invention, a planar light source comprises: a support member; a light guide member disposed on the support member and having a light source placement portion; and a light source disposed on the support member and disposed on the light source placement portion of the light guide member. The support member comprises: an insulating substrate having a first surface located on the light source side and a second surface located on the opposite side of the first surface; a first conductive layer disposed on the first surface of the insulating substrate and electrically connected to the light source; an adhesive layer disposed on the first surface of the insulating substrate and on the first conductive layer, and in contact with the first surface of the insulating substrate and the first conductive layer; and a light-reflective sheet disposed on the adhesive layer. [Effects of the Invention]

[0007] According to one embodiment of the present invention, the planar light source can be made thin. Simple Explanation of the Diagram

[0008] Figure 1 is a top view of the planar light source in the first embodiment. Figure 2 is a bottom view of the light source configuration and its surrounding area of ​​the planar light source in the first embodiment. Figure 3 is a cross-sectional view along line III-III of Figure 1. Figure 4 is a cross-sectional view of the light source configuration and its surrounding area in Figure 3. Figure 5A shows the bottom view of the light source in each implementation. Figure 5B is a cross-sectional view of line VB-VB in Figure 5A. Figure 5C is a cross-sectional view showing examples of variations in the light source for each implementation. Figure 5D is a cross-sectional view showing examples of variations in the light source for each implementation. Figure 6 is a cross-sectional view of the planar light source in the second embodiment. Figure 7 is a cross-sectional view of the planar light source in the third embodiment. Figure 8A is a cross-sectional view showing the second connecting part of the planar light source in the third embodiment. Figure 8B is a cross-sectional view showing a variation of the second connecting part of the planar light source in the third embodiment. Figure 9 is a cross-sectional view of the planar light source in the fourth embodiment. Implementation

[0009] The following description refers to the embodiments. Since the drawings are schematic representations of the embodiments, the scale, spacing, or positional relationships of the components may sometimes be exaggerated or omitted. Furthermore, as sectional views, sometimes only the cut surfaces are shown.

[0010] In the following description, constituent elements with substantially the same function are shown with common reference symbols, and sometimes the description is omitted. Also, terms indicating a specific direction or position are sometimes used (e.g., "up," "down," and other terms containing these terms). However, these terms are only used to facilitate understanding of the relative direction or position of the referenced diagram. If the relative direction or position of the terms "up," "down," etc., in the referenced diagram is the same, then in diagrams or actual products other than those disclosed herein, the arrangement may not be the same as the referenced diagram. In this specification, "parallel" includes not only the case where two lines, edges, or surfaces do not intersect even when extended, but also the case where the angle formed by two lines, edges, or surfaces intersects within a range of 10°. The positional relationship represented as "up" in this specification also includes cases where they are adjacent and cases where they are not adjacent but located above each other.

[0011] [First Implementation Form] Referring to Figures 1 to 5D, the planar light source 1 of the first embodiment will be described. The planar light source 1 includes a light guide member 10, a light source 20A, a support member 50, a first light-transmitting member 30, and a second light-adjusting member 40.

[0012] The following is a detailed description of each component constituting the planar light source 1.

[0013] <Light guide components> As shown in Figure 3, the light guide member 10 has a first upper surface 11 and a first lower surface 12 located on the opposite side of the first upper surface 11. In this specification, two directions that are parallel to and orthogonal to the first upper surface 11 of the light guide member 10 are defined as the first direction X and the second direction Y. Furthermore, the direction from the first lower surface 12 toward the first upper surface 11, which is orthogonal to the first direction X and the second direction Y, is defined as the third direction Z.

[0014] As shown in Figure 1, the light guide member 10 has a plurality of light guide portions 10a. Each light guide portion 10a is separated from the others in the first direction X and the second direction Y by a groove 14 described later. One light guide portion 10a can be configured as, for example, a driving unit for local dimming. Alternatively, the light guide member 10 may not be separated into a plurality of light guide portions 10a.

[0015] The light guide component 10 is a component that transmits light emitted by the light source 20A. The transmittance of the light guide component 10 relative to the peak wavelength of the light source 20A is preferably 50% or more, and more preferably 70% or more.

[0016] The material used for the light guide component 10 may be, for example, a thermoplastic resin such as acrylic acid, polycarbonate, cyclic polyolefin, polyethylene terephthalate or polyester, a thermosetting resin such as epoxy or silicone, or glass.

[0017] The thickness of the light guide member 10 is preferably 150 μm to 800 μm. In this specification, the thickness of each member represents the maximum distance between the upper and lower surfaces of each member in the third direction Z. The light guide member 10 may be composed of a single layer in the third direction Z, or it may be composed of a multilayer laminate. When the light guide member 10 is composed of a laminate, a light-transmitting adhesive layer may be disposed between the layers. Different types of main materials can be used for each layer of the laminate. For example, thermoplastic resins such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, or polyester, or thermosetting resins such as epoxy or silicone can be used as adhesive layers.

[0018] The light guide member 10 has a light source arrangement portion 13. The light source arrangement portion 13 is a through hole extending from the first upper surface 11 to the first lower surface 12. Alternatively, the light source arrangement portion 13 may also be a recess with an opening on the side of the first lower surface 12. The light guide member 10 has a plurality of light source arrangement portions 13. For example, one light source arrangement portion 13 is arranged in each of the plurality of light guide portions 10a. As shown in FIG1, the light source arrangement portion 13 may be, for example, circular when viewed from above. Also, the light source arrangement portion 13 may be, for example, elliptical, triangular, quadrilateral, hexagonal, or octagonal when viewed from above. In this specification, "viewed from above" means viewed from the third direction Z.

[0019] A groove 14 is formed in the light guide member 10 to separate the various light guide portions 10a from each other. By forming the groove 14, for example, warping of the planar light source caused by heat generation of the light source 20A can be suppressed. As shown in FIG1, in top view, the groove 14 extends in the first direction X and the second direction Y. As shown in FIG3, the groove 14 has a first groove portion 14a opening on the side of the first upper surface 11 and a second groove portion 14b opening on the side of the first lower surface 12. The first groove portion 14a and the second groove portion 14b are connected in the third direction Z. The width of the first groove portion 14a is wider than the width of the second groove portion 14b. The widths of the first groove portion 14a and the second groove portion 14b are widths in directions orthogonal to the direction in which the groove 14 extends.

[0020] As shown in Figure 3, a partition member 15 can be disposed within the first groove 14a. The partition member 15 is reflective of the light emitted by the light source 20A. The partition member 15 is, for example, a resin member containing light-scattering particles. The light-scattering particles of the partition member 15 can be, for example, titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass particles. The resin material of the partition member 15 can be, for example, a thermoplastic resin such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, or polyester resin, or a thermosetting resin such as epoxy resin or silicone resin. Alternatively, the partition member 15 can also be a metal member such as aluminum or silver. For example, the partition member 15 is disposed in a film-like manner along the inner surface of the first groove 14a. Furthermore, the dividing component 15 can also be filled into the first groove 14a.

[0021] The partition member 15 suppresses light guiding between adjacent light guide sections 10a. For example, the partition member 15 suppresses light guiding from a self-emitting light guide section 10a to a non-emitting light guide section 10a. In this way, when performing area dimming with each light guide section 10a as a driving unit, the brightness of each light guide section 10a can be easily controlled.

[0022] In Figure 3, the groove 14 extends from the first upper surface 11 of the light guide member 10 to the first lower surface 12. Alternatively, the groove 14 can be a bottomed groove with an opening on the first upper surface 11 side and its bottom not reaching the first lower surface 12. Also, the groove 14 can be a bottomed groove with an opening on the first lower surface 12 side and its bottom not reaching the first upper surface 11. Furthermore, the groove 14 can also be a hollow groove disposed inside the light guide member 10.

[0023] The light guide member 10 is positioned such that its first lower surface 12 faces the upper surface of the support member 50, and is disposed on the support member 50.

[0024] <Light Source> Light source 20A is disposed on light source placement section 13 of light guide member 10. Light source 20A is disposed on a plurality of light source placement sections 13. Light source 20A is preferably disposed on all of the plurality of light source placement sections 13, but light source 20A may not be disposed on a portion of the light source placement sections 13. Light source 20A is disposed on support member 50 on light source placement section 13.

[0025] Light source 20A includes a light-emitting element 21. The light-emitting element 21 includes a semiconductor multilayer. The semiconductor multilayer includes, for example, a substrate such as sapphire or gallium nitride, an n-type semiconductor layer and a p-type semiconductor layer disposed on the substrate, and a light-emitting layer sandwiched between them. Furthermore, the light-emitting element 21 includes an n-side electrode electrically connected to the n-type semiconductor layer and a p-side electrode electrically connected to the p-type semiconductor layer. Moreover, light source 20A includes a pair of positive and negative electrodes 25 disposed on its lower surface. One of the electrodes 25 is electrically connected to the p-side electrode, and the other is electrically connected to the n-side electrode.

[0026] Semiconductor stacks can also use substrate-removable structures. Furthermore, the structure of the light-emitting layer can be a double heterostructure, a single quantum well (SQW) structure with a single active layer, or a multi-quantum well (MQW) structure with a concentrated group of active layers. The light-emitting layer can emit visible light or ultraviolet light. The light-emitting layer can emit blue to red light as visible light. A semiconductor stack containing such a light-emitting layer can contain, for example, In xAl yGa 1-x-yN (0≦x, 0≦y, x+y≦1). The semiconductor stack can contain at least one light-emitting layer capable of the above-described light emission. For example, the semiconductor stack can be a structure containing one or more light-emitting layers between an n-type semiconductor layer and a p-type semiconductor layer, or a structure that repeatedly and sequentially includes an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. When a semiconductor multilayer comprises multiple light-emitting layers, it may include light-emitting layers with different emission peak wavelengths, or it may include light-emitting layers with the same emission peak wavelength. Furthermore, the same emission peak wavelength can, for example, exhibit a non-uniformity of several nanometers. This combination of light-emitting layers can be appropriately selected. For example, when the semiconductor multilayer comprises two light-emitting layers, the light-emitting layers can be selected according to combinations such as blue light with blue light, green light with green light, red light with red light, ultraviolet light with ultraviolet light, blue light with green light, blue light with red light, or green light with red light. Moreover, the light-emitting layers may comprise multiple active layers with different emission peak wavelengths, or multiple active layers with the same emission peak wavelength.

[0027] As shown in Figures 4-5B, the light source 20A may further include a second light-transmitting member 22. The second light-transmitting member 22 covers the upper surface and side surface of the light-emitting element 21. The second light-transmitting member 22 protects the light-emitting element 21, and, depending on the particles added to the second light-transmitting member 22, has functions such as wavelength conversion or light diffusion.

[0028] For example, the second light-transmitting member 22 may also include a light-transmitting resin, and further include a phosphor. For example, silicone resin or epoxy resin may be used as the light-transmitting resin. Furthermore, as fluoresces, yttrium aluminum garnet (YA) 5O 12:Ce, diaspore aluminum garnet (Lu) 3(Al,Ga) 5O 12:Ce, tetroxide aluminum garnet (Tb) 3(Al,Ga) 5O 12:Ce, CCA (Ca) 10(PO 4) 6Cl 2:Eu), SAE (Sr 4Al 14O 25:Eu), silicate chlorophosphate (Ca 8MgSi 4O 16Cl 2:Eu), β-silicon fluorescein ((Si,Al) 3(O,N) 4:Eu), and α-silicon fluorescein (Ca(Si,Al) 12(O,N)) can be used. Nitride-based fluorites such as 16:Eu), SLA-based fluorites (e.g., SrLiAl 3N 4:Eu), CASN-based fluorites (e.g., CaAlSiN 3:Eu) or SCASN-based fluorites (e.g., (Sr,Ca)AlSiN 3:Eu), KSF-based fluorites (e.g., K 2SiF 6:Mn), KSAF-based fluorites (e.g., K 2Si 0.99Al 0.01F 5.99:Mn) or MGF-based fluorites (e.g., 3.5MgO·0.5MgF 2·GeO 2:Mn), perovskite-structured fluorites (e.g., CsPb(F,Cl,Br,I) 3), or quantum dot fluorites (e.g., CdSe, InP, AgInS 2 or AgInSe 2), etc. As a phosphor added to the second light-transmitting member 22, one type of phosphor or multiple types of phosphors may be used.

[0029] As a KSAF-based phosphor, it may have a composition represented by the following formula (I).

[0030] In formula (I), M represents an alkali metal and may at least include K. Mn can be a tetravalent Mn ion. p, q, r, and s can satisfy 0.9 ≦ p + q + r ≦ 1.1, 0 < q ≦ 0.1, 0 < r ≦ 0.2, 5.9 ≦ s ≦ 6.1. Preferably, 0.95 ≦ p + q + r ≦ 1.05 or 0.97 ≦ p + q + r ≦ 1.03, 0 < q ≦ 0.03, 0.002 ≦ q ≦ 0.02 or 0.003 ≦ q ≦ 0.015, 0.005 ≦ r ≦ 0.15, 0.01 ≦ r ≦ 0.12 or 0.015 ≦ r ≦ 0.1, 5.92 ≦ s ≦ 6.05 or 5.95 ≦ s ≦ 6.025. For example, compositions represented by K2[Si0.946Al0.005Mn0.049F5.995], K2[Si0.942Al0.008Mn0.050F5.992], K2[Si0.939Al0.014Mn0.047F5.986] can be cited. According to this kind of KSAF-based phosphor, red light emission with high brightness and a narrow half-value width of the emission peak wavelength can be obtained.

[0031] Furthermore, a wavelength conversion sheet containing the above phosphor can also be disposed on the planar light source 1. The wavelength conversion sheet can serve as the planar light source 1, which absorbs a part of the blue light from the light source 20A and emits yellow light, green light, and / or red light to emit white light. For example, white light can be obtained by combining a light source 20A that can emit blue light with a wavelength conversion sheet containing a phosphor that can emit yellow light. In addition, a light source 20A that can emit blue light can also be combined with a wavelength conversion sheet containing a red phosphor and a green phosphor. Moreover, a light source 20A that can emit blue light can also be combined with a plurality of wavelength conversion sheets. As the plurality of wavelength conversion sheets, for example, a wavelength conversion sheet containing a phosphor that can emit red light and a wavelength conversion sheet containing a phosphor that can emit green light can be selected. Additionally, a light source 20A having a light-emitting element 21 that can emit blue light and a second light-transmissive member 22 containing a phosphor that can emit red light can also be combined with a wavelength conversion sheet containing a phosphor that can emit green light.

[0032] As the yellow phosphor for the wavelength conversion sheet, for example, it is preferable to use the above-mentioned yttrium aluminum garnet-based phosphor. Also, as the green phosphor for the wavelength conversion sheet, it is preferable to use a phosphor having a narrow half-value width of the emission peak wavelength, such as the above-mentioned phosphor having a perovskite structure or a quantum dot phosphor. Also, as the red phosphor for the wavelength conversion sheet, similar to the green phosphor, it is preferable to use a phosphor having a narrow half-value width of the emission peak wavelength, such as the above-mentioned KSF-based phosphor, KSAF-based phosphor, or quantum dot phosphor.

[0033] The light source 20A may further include a covering member 24. The covering member 24 is disposed on the lower surface of the light-emitting element 21. The covering member 24 is disposed such that the lower surface of the electrode 25 of the light source 20A is exposed from the covering member 24. The covering member 24 is also disposed on the lower surface of the second light-transmitting member 22 covering the side of the light-emitting element 21.

[0034] The coated component 24 is reflective of light emitted by the light source 20A. The coated component 24 is, for example, a resin component containing light-scattering particles. The light-scattering particles of the coated component 24 can be, for example, titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass particles. The resin material of the coated component 24 can be, for example, thermoplastic resins such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, or polyester resin, or thermosetting resins such as epoxy resin or silicone resin.

[0035] Furthermore, the light source 20A may also include a first light adjustment member 23. The first light adjustment member 23 is disposed on the upper surface of the light source 20A. The first light adjustment member 23 covers the upper surface of the light-emitting element 21. The first light adjustment member 23 is disposed on the upper surface of the second light-transmitting member 22, controlling the amount or direction of light emitted from the upper surface of the second light-transmitting member 22. The first light adjustment member 23 is both reflective and transmissive to the light emitted by the light-emitting element 21. Part of the light emitted from the upper surface of the second light-transmitting member 22 is reflected by the first light adjustment member 23, and the other part passes through the first light adjustment member 23. The transmittance of the first light adjustment member 23 relative to the light emitted by the light-emitting element 21 is preferably, for example, 1% to 50%, more preferably 3% to 30%. This reduces the brightness directly above the light source 20A and alleviates the brightness unevenness of the planar light source 1.

[0036] The first light-adjusting member 23 can be constructed from a light-transmitting resin and light-scattering particles contained within the resin. For example, the light-transmitting resin can be a thermoplastic resin such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, or polyester resin, or a thermosetting resin such as epoxy resin or silicone resin. For the light-scattering particles, for example, particles such as titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass can be used. Furthermore, the first light-adjusting member 23 can also be, for example, a metal component such as Al or Ag, or a dielectric multilayer film.

[0037] The light source may also not include the covered member 24. For example, the light source 20B shown in FIG5C has its lower surface composed of the lower surface of the light-emitting element 21 and the lower surface of the second light-transmitting member 22.

[0038] Furthermore, as shown in Figure 5D, the light source 20C can also be a single unit of the light-emitting element 21. The first light adjustment member 23 is disposed on the upper surface of the light-emitting element 21. Also, in Figure 5D, although the light source 20C does not have a covering member 24 disposed on the lower surface of the light-emitting element 21, the covering member 24 can still be disposed on the lower surface of the light-emitting element 21.

[0039] <First Transparent Component> The first light-transmitting member 30 is disposed between the side of the light source 20A in the light source arrangement section 13 of the light guide member 10 and the light guide member 10, and above the light source 20A. The first light-transmitting member 30 covers the upper surface and side of the light source 20A. Preferably, the first light-transmitting member 30 is in contact with the light guide member 10 and the light source 20A. In this way, light from the light source 20A can be easily guided to the light guide member 10.

[0040] The first light-transmitting member 30 is transparent to light emitted by the light source 20A. The transmittance of the first light-transmitting member 30 relative to the peak wavelength of the light source 20A is preferably 50% or more, and more preferably 70% or more. The material of the first light-transmitting member 30 can be, for example, resin. For example, the same resin as the material of the light guide member 10, or a resin with a smaller difference in refractive index than the material of the light guide member 10, can be used as the material of the first light-transmitting member 30.

[0041] The first light-transmitting member 30 in the third direction Z can be composed of a single layer or a multilayer laminate. Furthermore, the first light-transmitting member 30 may contain phosphors or light-scattering particles. When the first light-transmitting member 30 is a laminate, each layer may contain phosphors and / or light-scattering particles, or may not contain them. For example, the first light-transmitting member 30 may be composed of layers containing phosphors and layers not containing phosphors.

[0042] The first light-transmitting member 30 has a first light-transmitting portion 31 located on the first light-adjusting member 23 of the light source 20A, and a second light-transmitting portion 32 located between the side of the light source 20A and the light guide member 10.

[0043] <Second Light Adjustment Component> The second light adjustment member 40 is disposed on the first light-transmitting member 30. As shown in FIG1, the second light adjustment member 40 is disposed at a position overlapping the light source arrangement section 13, which is provided with the light source 20A and the first light-transmitting member 30, when viewed from above.

[0044] The second light adjustment member 40 is reflective and transparent to the light emitted by the light source 20A. The transmittance of the second light adjustment member 40 relative to the peak wavelength of the light source 20A is preferably 1% to 50%, and more preferably 3% to 30%.

[0045] The second light-adjusting member 40 can be constructed from a light-transmitting resin and light-scattering particles contained within the resin. For example, the light-transmitting resin can be a thermoplastic resin such as acrylic resin, polycarbonate resin, cyclic polyolefin resin, polyethylene terephthalate resin, or polyester resin, or a thermosetting resin such as epoxy resin or silicone resin. For the light-scattering particles, for example, particles such as titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass can be used. Furthermore, the second light-adjusting member 40 can also be a metal component such as aluminum or silver, or a dielectric multilayer film.

[0046] The upper surface 40a of the second light adjustment member 40, together with the first upper surface 11 of the light guide member 10, functions as the light-emitting surface (light-exiting surface) of the planar light source 1. The second light adjustment member 40 reflects a portion of the light directed towards the light source arrangement section 13 where the light source 20A is arranged, while allowing the other portion to pass through. In this way, the brightness difference between the area directly above and around the light source 20A and other areas can be reduced on the light-emitting surface of the planar light source 1. This reduces the uneven brightness of the light-emitting surface of the planar light source 1.

[0047] A first light-transmitting portion 31 of a first light-transmitting member 30 is disposed between the second light-adjusting member 40 and the first light-adjusting member 23 of the light source 20A. The transmittance of the first light-transmitting member 30 relative to the light emitted by the light source 20A is higher than that of the first light-adjusting member 23 and the second light-adjusting member 40. The transmittance of the first light-transmitting member 30 relative to the light emitted by the light source 20A is in the range of less than 100%, and can be set to be more than 2 times and less than 100 times the transmittance of the first light-adjusting member 23 and the second light-adjusting member 40. In the first light-transmitting portion 31 between the second light-adjusting member 40 and the first light-adjusting member 23, light emitted from the side of the light source 20A or light reflected by the light-reflecting sheet 53 is guided around. In this way, the area directly above the light source 20A will not become too bright or too dark, and as a result, the brightness unevenness of the light-emitting surface of the planar light source 1 can be reduced.

[0048] Since a portion of the light emitted directly upward from the light source 20A is suppressed by the first light adjustment member 23, in order to prevent the area directly above the light source 20A from becoming too dark, it is preferable that the transmittance of the second light adjustment member 40 is higher than the transmittance of the first light adjustment member 23 relative to the light emitted by the light source 20A.

[0049] <Supporting Components> The support member 50 has an insulating substrate 60, a first conductive layer 81, a first adhesive layer 51, and a light-reflective sheet 53.

[0050] The insulating substrate 60 has a first surface 61 located on the side of the light source 20A and a second surface 62 located on the opposite side of the first surface 61. The insulating substrate 60 is preferably a highly flexible component, but it can also be a highly rigid component. Materials used for the insulating substrate 60 include, for example, resins such as polyester and polyimide, or epoxy glass. Examples of polyesters include polyethylene terephthalate or polyethylene naphthalate.

[0051] The first conductive layer 81 is disposed on the first surface 61 of the insulating substrate 60 and is electrically connected to the light source 20A. The first conductive layer 81 is a metal layer that does not contain resin. For example, the first conductive layer 81 is a copper layer. In addition to copper, the first conductive layer 81 may also be an aluminum layer, a nickel layer, a silver layer, or a gold layer.

[0052] A first bonding layer 51 is disposed between the first surface 61 of the insulating substrate 60 and the light-reflective sheet 53, bonding the insulating substrate 60 and the light-reflective sheet 53. The first bonding layer 51 is disposed on the first surface 61 of the insulating substrate 60 and on the first conductive layer 81, and is in contact with the first surface 61 of the insulating substrate 60 and the first conductive layer 81. The first bonding layer 51 also serves as a protective layer covering the first conductive layer 81; no other layers are disposed between the first bonding layer 51 and the first surface 61 of the insulating substrate 60, and between the first bonding layer 51 and the first conductive layer 81. The first bonding layer 51 is in contact with the first surface 61 of the insulating substrate 60 and the first conductive layer 81. This allows for a thinner support member 50, resulting in a thinner planar light source 1. The first conductive layer 81 is embedded within the first bonding layer 51. This further allows for a thinner support member 50 and the planar light source 1. Furthermore, the first bonding layer 51 is bonded to the light-reflective sheet 53. This also allows the support member 50 and the planar light source 1 to be made thinner.

[0053] The first adhesive layer 51 is a resin layer. For example, epoxy resin, acrylic resin, or cyclic polyolefin resin can be used as the resin for the first adhesive layer 51. Furthermore, the first adhesive layer 51 may contain light-scattering particles in the resin. For example, particles such as titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass can be used as light-scattering particles.

[0054] The light-reflective sheet 53 is disposed below the first lower surface 12 of the light guide member 10, below the light source 20A, below the first light-transmitting member 30, and below the groove 14. The light-reflective sheet 53 is reflective of the light emitted by the light source 20A. For example, a resin sheet containing multiple air bubbles or a resin sheet containing light-scattering particles can be used as the light-reflective sheet 53. For example, polyethylene terephthalate (PET) resin, cyclic polyolefin resin, acrylic resin, silicone resin, polyurethane resin, or epoxy resin can be used as the resin. For example, titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass particles can be used.

[0055] In the region between the light-reflective sheet 53 and the first upper surface 11 of the light guide member 10, light from the light source 20A is repeatedly reflected by the light-reflective sheet 53 and the first upper surface 11, and is guided by the guide groove 14 within the light guide member 10. A portion of the light directed toward the first upper surface 11 is extracted from the first upper surface 11 to the outside of the light guide member 10. Because a portion of the light directed toward the first lower surface 12 is reflected by the light-reflective sheet 53 toward the first upper surface 11, the brightness of the light extracted from the first upper surface 11 can be increased.

[0056] Furthermore, when the first bonding layer 51 disposed below the light-reflective sheet 53 contains light-scattering particles as described above, the brightness of the light emitted from the first upper surface 11 can be further improved.

[0057] The support member 20 may further include a second bonding layer 52. The second bonding layer 52 is disposed between the light-reflective sheet 53 and the first lower surface 12 of the light guide member 10, bonding the light-reflective sheet 53 to the light guide member 10. Furthermore, the light source 20A is disposed on the second bonding layer 52 within the light source placement portion 13 of the light guide member 10. The second bonding layer 52 is transparent to light emitted by the light source 20A. For example, epoxy resin, acrylic resin, or cyclic polyolefin resin can be used as the material for the second bonding layer 52.

[0058] The support member 50 may further include a first connecting portion 70. The first connecting portion 70 has a first part 71 and a second part 72. The first part 71 is disposed in a second hole h2 that penetrates the second adhesive layer 52, the light-reflective sheet 53, the first adhesive layer 51, and the insulating substrate 60 in the third direction Z, and is located below the light source 20A. The second part 72 is disposed on the second surface 62 of the insulating substrate 60 and is connected to the first part 71.

[0059] Part 1 71 and Part 2 72 are preferably integrally formed from the same material, for example. Part 1 71 and Part 2 72 may also be different components. The first connecting portion 70 may, for example, contain resin and conductive particles contained in the resin. The resin used as the first connecting portion 70 may be, for example, epoxy resin, polyurethane resin, or phenolic resin. The conductive particles may, for example, be metal particles such as copper, silver, nickel, or gold. Furthermore, particles containing carbon materials may also be used as conductive particles.

[0060] Corresponding to the positive and negative electrodes 25 of the light source 20A, a pair of first connection portions 70 are arranged separately from each other. The first portion 71 of one first connection portion 70 is connected to the positive electrode 25 below the light source 20A. The first portion 71 of the other first connection portion 70 is connected to the negative electrode 25 below the light source 20A.

[0061] Part 72a of the second part 72 penetrates the insulating substrate 60 and is connected to the first conductive layer 81. Therefore, the electrode 25 of the light source 20A is electrically connected to the first conductive layer 81 via the first connection portion 70.

[0062] The first conductive layer 81 is a metal layer without resin, and its resistance is lower than that of a conductive layer containing resin. Therefore, the first conductive layer 81 can be thinner than a conductive layer containing resin. Furthermore, the heat generated by the first conductive layer 81 is less than that of a conductive layer containing resin, which can suppress the deterioration of the first bonding layer 51 adjacent to the first conductive layer 81. According to the first embodiment, compared to the case where both the first conductive layer 81 and the first connecting portion 70 are composed of resin, the support member 50 and the planar light source 1 can be made thinner.

[0063] The support member 50 may further include a protective layer 54. The protective layer 54 is disposed on the second surface 62 of the insulating substrate 60, directly covering and protecting the first connection portion 70. As a material for the protective layer 54, for example, polyurethane resin, acrylic resin, phenolic resin, polyolefin resin or epoxy resin can be used.

[0064] As shown in Figure 2, in a top view, at least a portion of the first conductive layer 81 overlaps with the light source arrangement portion 13. Also, in a top view, at least a portion of the first connecting portion 70 overlaps with the light source arrangement portion 13. Therefore, by means of the first conductive layer 81 or the first connecting portion 70, light escaping below the light source arrangement portion 13 can be suppressed, and the brightness of the light emitted from the first upper surface 11 can be increased.

[0065] [Second Implementation] Figure 6 is a cross-sectional view of the area light source 2 in the second embodiment, including the light source configuration section 13.

[0066] The first conductive layer 81 of the planar light source 2 in the second embodiment includes resin and conductive particles contained in the resin. The resin used as the first conductive layer 81 can be, for example, epoxy resin, polyurethane resin, or phenolic resin. The conductive particles can be, for example, metal particles such as copper, silver, nickel, or gold. Furthermore, particles containing carbon materials can also be used as conductive particles. Because the first conductive layer 81 includes resin, the adhesion between the first conductive layer 81 and the first adhesive layer 51 can be improved.

[0067] Furthermore, the first conductive layer 81 has an end portion 81a that is thinner towards the end in the extension direction. The extension direction of the first conductive layer 81 includes a first direction X and a second direction Y. The lower surface of the end portion 81a is in contact with the first surface 61 of the insulating substrate 60. The first adhesive layer 51 covers the upper surface of the end portion 81a. The upper surface of the end portion 81a is a curved surface or an inclined surface that is inclined relative to the first surface 61 of the insulating substrate 60, which can improve the adhesion with the first adhesive layer 51. The end portion 81a is the portion extending from the end of the first conductive layer 81, for example, less than 50 μm.

[0068] [Third Implementation Form] Figure 7 is a cross-sectional view of the portion of the planar light source 3 including the light source configuration section 13 in the third embodiment.

[0069] The support member 50 of the planar light source 3 in the third embodiment further includes a second conductive layer 82 disposed on the second surface 62 of the insulating substrate 60. The second conductive layer 82 is connected to the second portion 72 of the first connecting portion 70 on the second surface 62 of the insulating substrate 60. For example, a portion of the second conductive layer 82 is covered by the second portion 72. The second conductive layer 82 is a metal layer that does not contain resin, and the same material as the first conductive layer 81 can be used as the material of the second conductive layer 82.

[0070] The first conductive layer 81 disposed on the first surface 61 of the insulating substrate 60 is electrically connected to the conductive member (the second conductive layer 82 and the second portion 72 of the first connecting portion 70) disposed on the second surface 62 of the insulating substrate 60. In the conductive member disposed on the second surface 62, since the second portion 72 of the first connecting portion 70 contains resin, its adhesion to the protective layer 54 is improved; and since the second conductive layer 82 does not contain resin, it has low resistance. Therefore, the conductive member disposed on the second surface 62 can simultaneously improve its adhesion to the protective layer 54 and reduce its resistance.

[0071] Figure 8A is a cross-sectional view showing an example of the connection between the second conductive layer 82 and the first conductive layer 81. The support member 50 in the third embodiment further includes: a first hole h1 that at least penetrates the insulating substrate 60; and a second connecting portion 90 disposed in the first hole h1 and electrically connecting the first conductive layer 81 and the second conductive layer 82. In this embodiment, the first hole h1 is located away from the cross-section of FIG7. The second connecting portion 90 comprises resin and conductive particles contained in the resin. For example, epoxy resin, polyurethane resin, or phenolic resin can be used as the resin for the second connecting portion 90. For example, metal particles such as copper, silver, nickel, or gold can be used as the conductive particles. Furthermore, particles containing carbon materials can also be used as the conductive particles.

[0072] In the example shown in Figure 8A, the first hole h1 also penetrates the second conductive layer 82. The second connecting portion 90 has a first part 91 and a second part 92. The first part 91 is disposed within the first hole h1. The second part 92 is disposed on the second lower surface 82b of the second conductive layer 82, opposite to the second upper surface 82a that contacts the second surface 62 of the insulating substrate 60. The second part 92 of the second connecting portion 90 contacts the second lower surface 82b of the second conductive layer 82 at the periphery of the first hole h1.

[0073] A second conductive layer 82 is disposed on the second surface 62 of the insulating substrate 60, and a first conductive layer 81 is not disposed on the first surface 61 of the insulating substrate 60. For example, a first hole h1 penetrating the insulating substrate 60 and the second conductive layer 82 can be formed by means of a drill, punch, or laser. After forming the first hole h1, conductive paste is supplied into the first hole h1, and conductive paste is also supplied to the second lower surface 82b of the second conductive layer 82 around the first hole h1. By hardening the conductive paste, a second connecting portion 90 is formed. After forming the second connecting portion 90, the first conductive layer 81 is formed on the first surface 61 of the insulating substrate 60 in such a way that it contacts the surface 90a of the second connecting portion 90 exposed from the first hole h1.

[0074] The second connecting portion 90 is in contact not only with the inner circumferential surface of the portion of the first hole h1 that penetrates the second conductive layer 82, but also with the second lower surface 82b of the second conductive layer 82. That is, the contact area between the second connecting portion 90 and the second conductive layer 82 can be made larger than the contact area between the second connecting portion 90 and the first conductive layer 81, thereby reducing the contact resistance between the second connecting portion 90 and the second conductive layer 82.

[0075] Figure 8B is a cross-sectional view showing another example of the connection between the second conductive layer 82 and the first conductive layer 81. A second conductive layer 82 is disposed on the second surface 62 of the insulating substrate 60, and a first hole h1 is formed by irradiation from the first surface 61 side of the insulating substrate 60 when the first conductive layer 81 is not disposed thereon. The first hole h1 penetrates the insulating substrate 60 but does not penetrate the second conductive layer 82. Subsequently, conductive paste is supplied into the first hole h1 and the conductive paste is hardened. Thereby, a second connection portion 93 connecting the first conductive layer 81 and the second conductive layer 82 is formed.

[0076] [Fourth Implementation Form] Figure 9 is a cross-sectional view of the area light source 4 in the fourth embodiment, including the light source configuration section 13.

[0077] In the fourth embodiment of the planar light source 4, similar to the third embodiment of the planar light source 3, a second conductive layer 82 is disposed on the second surface 62 of the insulating substrate 60. The first conductive layer 81 and the second conductive layer 82 are electrically connected by the second connecting portion 90 shown in FIG8A or the second connecting portion 93 shown in FIG8B.

[0078] Furthermore, the first conductive layer 81 in the fourth embodiment, like in the second embodiment, includes resin and conductive particles contained within the resin. Moreover, the first conductive layer 81 has an end portion 81a that is thinner towards the extending direction. The lower surface of the end portion 81a is in contact with the first surface 61 of the insulating substrate 60. The first adhesive layer 51 covers the upper surface of the end portion 81a. The upper surface of the end portion 81a is curved or inclined relative to the first surface 61 of the insulating substrate 60, which improves the adhesion to the first adhesive layer 51.

[0079] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. Based on the above embodiments of the present invention, all embodiments that can be appropriately designed and modified by those skilled in the art, as long as they contain the spirit of the present invention, are also within the scope of the present invention. Furthermore, within the scope of the concept of the present invention, those skilled in the art will be able to conceive of various modifications and alterations, and such modifications and alterations are also within the scope of the present invention.

[0080] 1~4: Planar light source 10: Light guide components 10a: Light guide section 11: First upper surface 12: First lower surface 13: Light Source Configuration Department 14: Slot 14a: First groove 14b: Second groove 15: Zoning Components 20A~20C: Light source 21: Light-emitting element 22: Second light-transmitting component 23: First Light Adjustment Component 24: Covered components 25: Electrode 30: First light-transmitting component 31: First light-transmitting section 32: Second light-transmitting section 40: Second light adjustment component 40a: Upper surface 50: Supporting components 51: The first layer continues 52: The second layer continues 53: Light-reflective sheets 54: Protective layer 60: Insulating substrate 61: Page 1 62: Page 2 70: First connecting part 71: Part 1 72: Part 2 72a: Part 81: First conductive layer 81a: end 82: Second conductive layer 82a: Second upper surface 82b: Second lower surface 90: Second connecting part 90a: Surface 91: Part 1 92: Part 2 93: Second connecting part h1: First hole h2: Second hole

Claims

1. A planar light source comprising: a support member; a light guide member disposed on the support member and having a light source placement portion; and a light source disposed on the support member and disposed on the light source placement portion of the light guide member; wherein the support member comprises: an insulating substrate having a first surface located on the light source side and a second surface located on the opposite side of the first surface; a first conductive layer disposed on the first surface of the insulating substrate and electrically connected to the light source; an adhesive layer disposed on the first surface of the insulating substrate and on the first conductive layer, and in contact with the first surface of the insulating substrate and the first conductive layer; and a light-reflective sheet disposed on the adhesive layer; wherein the adhesive layer is in contact with the light-reflective sheet and contains light-scattering particles.

2. The planar light source as claimed in claim 1, wherein, in a top view, the first conductive layer overlaps with the light source arrangement portion.

3. The planar light source of claim 1, wherein the support member further comprises: a second conductive layer disposed on the second surface of the insulating substrate and electrically connected to the first conductive layer.

4. The planar light source as claimed in claim 3, wherein the first conductive layer comprises resin and conductive particles.

5. The planar light source of claim 4, wherein the first conductive layer has an end that is thinner towards the end, and the end is in contact with the insulating substrate.

6. The planar light source as claimed in claim 3, wherein the first conductive layer does not include a resin metal layer.

7. The planar light source of claim 3, wherein the second conductive layer is a metal layer that does not contain resin; and the support member further comprises: a first connecting portion disposed on the second surface, connected to the second conductive layer and containing resin and conductive particles; and a protective layer that directly covers the second conductive layer and the first connecting portion, and contains resin.

8. The planar light source of claim 7, wherein the support member further comprises: a first hole that at least penetrates the insulating substrate; and a second connecting portion disposed in the first hole and electrically connecting the first conductive layer and the second conductive layer.

9. The planar light source of claim 8, wherein the first aperture further penetrates the second conductive layer; the second connecting portion is disposed on the lower surface opposite to the upper surface of the second conductive layer that is in contact with the second surface of the insulating substrate; and the contact area between the second connecting portion and the second conductive layer is greater than the contact area between the second connecting portion and the first conductive layer.

10. The planar light source as claimed in claim 8, wherein the second connecting portion comprises resin and conductive particles.

11. The planar light source of any one of claims 7 to 10, wherein the support member further has a second hole penetrating the light-reflective sheet, the adhesive layer and the insulating substrate and located below the light source; and the first connecting portion is further disposed within the second hole.

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