Light emitting module

Abstract

The present invention provides a light-emitting module, which can reduce uneven brightness or color within the light-emitting surface of a light guide plate. The light guide plate is polygonal in shape with multiple corners when viewed from above, and has a first main surface that serves as a light-emitting surface, a second main surface on the opposite side of the first main surface, and a recessed portion arranged on the second main surface. A light source is arranged in the recessed portion. The recessed portion has an opening on the second main surface side and a bottom surface that is polygonal in shape when viewed from above. The light source has a side surface along the edge of the bottom surface of the recessed portion. In a top view, the diagonal lines connecting the multiple corners of the first main surface intersect with the edge of the bottom surface of the recessed portion.

Description

Technical Field

[0001] The invention relates to a light emitting module. Background Art

[0002] Light-emitting modules using light-emitting diodes and other light-emitting elements are widely used as surface light sources such as backlights of liquid crystal displays. For example, in a direct-type liquid crystal display in which a surface light source is arranged on the back of a liquid crystal panel, there is a high demand for a thinner surface light source. When the distance between the light source and the light-emitting surface of the light guide plate becomes shorter as the surface light source becomes thinner, the light cannot be fully diffused, and uneven brightness or color is easily generated on the light-emitting surface.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-133304 Summary of the invention

[0006] The present invention provides a light emitting module capable of reducing uneven brightness or uneven color within a light emitting surface of a light guide plate.

[0007] According to one embodiment of the present invention, a light-emitting module includes a light guide plate and a light source. The light guide plate is polygonal in shape with a plurality of corners when viewed from above, and has a first principal surface that serves as a light-emitting surface, a second principal surface on the opposite side of the first principal surface, and a recessed portion provided on the second principal surface. The light source is provided in the recessed portion. The recessed portion has an opening on the second principal surface side and a bottom surface that is polygonal in shape when viewed from above. The light source has a side surface along the edge of the bottom surface of the recessed portion. In a plan view, a diagonal line connecting the plurality of corners of the first principal surface intersects with the edge of the bottom surface of the recessed portion.

[0008] According to the present invention, it is possible to provide a light emitting module capable of reducing uneven brightness or uneven color within a light emitting surface of a light guide plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 1 is a schematic top view of a light emitting module according to an embodiment.

[0010] Figure 2 yes Figure 1 A-A section diagram in .

[0011] Figure 3 yes Figure 1 B-B section diagram in.

[0012] Figure 4 This is a perspective view of elements in the recessed portion of the light guide plate in the light emitting module according to the embodiment.

[0013] Figure 5 Schematic diagram of a boundary surface between a light guide plate and a light-transmitting portion in a light-emitting module according to an embodiment.

[0014] Fig. 6A This is a schematic cross-sectional view showing a method for manufacturing a light emitting module according to an embodiment.

[0015] Figure 6B This is a schematic cross-sectional view showing a method for manufacturing a light emitting module according to an embodiment.

[0016] Figure 6C This is a schematic cross-sectional view showing a method for manufacturing a light emitting module according to an embodiment.

[0017] Figure 7 is a schematic top view of a light emitting module according to another embodiment.

[0018] Description of Reference Numerals

[0019] 1.100: Light-emitting module

[0020] 2: Unit

[0021] 2a: Corner of unit

[0022] 10: Light guide plate

[0023] 11: First main surface

[0024] 11a: Corner of the first main surface

[0025] 12: Second main surface

[0026] 15: concave part

[0027] 16: Opening of the concave portion

[0028] 17: Bottom of the recess

[0029] 17a: Long side

[0030] 20: Light Source

[0031] 21: Light-emitting element

[0032] 22: Phosphor layer

[0033] 22a: Side view of phosphor layer

[0034] 60: light-transmitting part

[0035] 61: Inclined surface of light-transmitting part DETAILED DESCRIPTION

[0036] Hereinafter, the embodiment will be described with reference to the drawings. In addition, in each of the drawings, the same reference numerals are given to the same elements.

[0037] Figure 1 It is a schematic plan view of the light emitting module 1 according to the embodiment.

[0038] Figure 2 yes Figure 1 A-A section diagram in .

[0039] The light emitting module 1 includes a light guide plate 10 and a light source 20 . The light source 20 includes a light emitting element 21 , a fluorescent layer 22 , and a covering member 23 .

[0040] The light guide plate 10 is transparent to the light emitted by the light source 20. As the material of the light guide plate 10, for example, thermoplastic resins such as acryl, polycarbonate, cyclic polyolefin, polyethylene terephthalate, polyester, thermosetting resins such as epoxy, silicon, glass, etc. can be used. Among them, polycarbonate is preferred because it is highly transparent and inexpensive.

[0041] The light guide plate 10 has a first main surface 11 serving as a light emitting surface, a second main surface 12 on the opposite side of the first main surface 11, and a recess 15 provided on the second main surface 12. The light guide plate 10 also has a side surface 13 connected to the first main surface 11 and an inclined surface 14 provided between the side surface 13 and the second main surface 12.

[0042] At least the phosphor layer 22 in the light source 20 is arranged in the recess 15 of the light guide plate 10. The light emitting element 21 is provided on the surface of the phosphor layer 22 opposite to the surface on the first principal surface 11 side of the light guide plate 10. The recess 15 can function as a positioning portion for the light source 20 relative to the light guide plate 10.

[0043] The light emitting element 21 has a main light emitting surface 21b and a pair of positive and negative electrodes 21a provided on the opposite side of the main light emitting surface 21b. The light emitting element 21 has a semiconductor stacking structure. The semiconductor stacking structure includes, for example, In x Al y Ga 1-x-y N(0x, 0y, x+y1) can emit blue light.

[0044] The main light emitting surface 21b of the light emitting element 21 is bonded to the phosphor layer 22 by, for example, a light-transmitting adhesive. Figure 2 and Figure 3 In the example shown, the side surface of the light emitting element 21 and the electrode 21a are located outside the recess 15. Alternatively, the light emitting element 21 may be arranged in the recess 15. A covering member 23 is provided on the side surface of the light emitting element 21. The covering member 23 is also provided between the electrodes 21a on the lower surface of the light emitting element 21. The covering member 23 has reflectivity with respect to the light emitted by the light emitting element 21 and the phosphor in the phosphor layer 22, and is, for example, a resin containing a white pigment or the like. The covering member 23 is particularly preferably a silicone resin containing titanium oxide.

[0045] The phosphor layer 22 has a base material and phosphors dispersed in the base material. As the material of the base material of the phosphor layer 22, for example, epoxy resin, silicone resin, glass, etc. can be used. From the viewpoint of light resistance and ease of molding, silicone resin is preferably used as the base material.

[0046] The phosphor is excited by the light emitted by the light emitting element 21, and emits light of a wavelength different from the wavelength of the light emitted by the light emitting element 21. As the phosphor, for example, YAG phosphor, LAG phosphor, β-silicon aluminum oxynitride ceramic phosphor, CASN phosphor, KSF series phosphor, quantum dot phosphor, etc. can be used. The phosphor layer 22 can also include multiple types of phosphors.

[0047] An optical function portion 32 is provided on the first main surface 11 side of the light guide plate 10. The optical function portion 32 is provided at a position facing the recess 15 formed on the second main surface 12. The optical axis of the light emitting element 21 and the optical axis of the optical function portion 32 are preferably substantially consistent. The shape of the optical function portion 32 is, for example, an inverted cone, an inverted quadrangular pyramid, an inverted hexagonal pyramid, or an inverted circular truncated cone or an inverted polygonal truncated cone.

[0048] The optical function part 32 is a light-transmitting resin, glass or air layer having a refractive index lower than that of the light guide plate 10, and refracts light at the interface between the light guide plate 10 and the optical function part 32, and can function as a lens that diffuses light in the surface direction of the light guide plate 10. In addition, for example, a component in which a light-reflective material (for example, a reflective film such as a metal or a white resin) is provided in a recess having an inclined surface may be used.

[0049] The recess 15 is opened from the second main surface 12 side, and has a bottom surface 17 on the side closer to the first main surface 11 than the second main surface 12. A light scattering layer 31 containing a light scattering agent is provided on the bottom surface 17 of the recess 15. The light scattering layer 31 is provided between the bottom surface 17 of the recess 15 and the phosphor layer 22. The light scattering layer 31 scatters a part of the light emitted in the direction directly above the light emitting element 21 and returns it to the bottom. Thus, it is possible to prevent the light emitting surface of the light emitting module 1, that is, the first main surface 11 of the light guide plate 10, and the vicinity directly above the light source 20 from being too bright compared to other areas. The light scattering layer 31 can be omitted, or the phosphor layer 22 can be directly provided on the bottom surface 17 of the recess 15.

[0050] A light-transmitting portion 60 is provided around the light source in the recess 15 (around the fluorescent layer 22 and around the light scattering layer 31). The light-transmitting portion 60 is a light-transmitting resin portion that is transparent to the light emitted by the light source 20. The refractive index of the light-transmitting resin portion is lower than the refractive index of the light guide plate 10. Alternatively, the light-transmitting portion 60 may be a void (air layer).

[0051] The light guide plate 10 has an inclined surface 14 which forms an obtuse angle with the second main surface 12 and is continuous with the second main surface 12. The inclined surface 14 and the second main surface 12 are covered with a light reflective resin portion 40.

[0052] The light reflective resin portion 40 has reflectivity with respect to the light emitted from the light source 20 and is, for example, a resin containing a white pigment, etc. The light reflective resin portion 40 is preferably a silicone resin containing titanium oxide.

[0053] The electrode 21a of the light emitting element 21 is bonded to the wiring 52. The light reflective resin portion 40 has insulating properties and covers the side surfaces of the electrode 21a of the light emitting element 21.

[0054] The light reflective resin portion 40 is bonded to a wiring substrate 50. The wiring substrate 50 includes an insulating base 51, wiring 54 provided on the back surface of the base 51, and a support 53 penetrating the base 51. The support 53 connects the wiring 52 and the wiring 54, and the electrode 21a of the light emitting element 21 is electrically connected to the wiring 54 through the wiring 52 and the support 53.

[0055] As the base material 51 of the wiring board 50, for example, resin or ceramic can be used. As the wirings 52 and 54 and the support column 53, for example, copper can be used.

[0056] In this manual, if Figure 1 As shown, the plan view shows a plan view of the first main surface 11 of the light guide plate 10. In this plan view, the first main surface 11 is a polygonal shape having a plurality of corners 11a, for example, a quadrilateral shape having four corners 11a.

[0057] The bottom surface 17 of the recess 15 is also polygonal in a plan view. For example, the bottom surface 17 of the recess 15 has four long sides 17a and four short sides 17b shorter than the long sides 17a. The bottom surface 17 has corners between the long sides 17a and the short sides 17b.

[0058] The phosphor layer 22 is polygonal in plan view. The phosphor layer 22 is, for example, quadrilateral in plan view and has four side surfaces 22a. The four side surfaces 22a are along the long sides 17a of the bottom surface 17 of the recess 15. In plan view, the corners of the phosphor layer 22 are located opposite to the short sides 17b of the bottom surface 17 of the recess 15.

[0059] In a plan view, a diagonal line connecting corners 11a at diagonal positions of first main surface 11 intersects long side 17a of bottom surface 17 of recess 15. Phosphor layer 22 is positioned on bottom surface 17 of recess 15 such that side surface 22a of phosphor layer 22 is along long side 17a of bottom surface 17 of recess 15.

[0060] The light source 20, which is a quadrilateral when viewed from above, is arranged to be rotated, for example, 45 degrees relative to the quadrilateral of the first main surface 11 of the light guide plate 10, and when viewed from above, the diagonal connecting the corners 11a of the first main surface 11 and the side surface of the light source 20, i.e., the side surface 22a of the phosphor layer 22 (the side of the quadrilateral phosphor layer 22) intersect. When viewed from above, the corner of the light source 20 (the corner of the phosphor layer 22) is not located on the diagonal connecting the corners 11a of the first main surface 11, and is not located opposite to the corner 11a. When viewed from above, the corner of the light source 20 (the corner of the phosphor layer 22) is located in the area divided by the diagonal connecting the corners 11a of the first main surface 11.

[0061] In the phosphor layer 22 , the side surfaces 22 a have a larger area than the corners, and the brightness of light emitted from the side surfaces 22 a of the phosphor layer 22 tends to be higher than the brightness of light emitted in a diagonal direction of the phosphor layer 22 .

[0062] In the quadrilateral first main surface 11 of the light guide plate 10 , the distance between the center portion where the fluorescent layer 22 is arranged and the corner portion 11 a is longer than the distance between the center portion and the side portion. Therefore, light tends to be less likely to diffuse at the four corners of the first main surface 11 .

[0063] According to the present embodiment, the phosphor layer 22 is arranged on the light guide plate 10 in such a manner that the diagonal line connecting the corner 11a of the first main surface 11 intersects with the side surface 22a of the phosphor layer 22, and the side surface 22a of the phosphor layer 22 is positioned opposite to the corner 11a of the first main surface 11, thereby making it possible to easily diffuse the light emitted from the phosphor layer 22 to the four corners of the first main surface 11 of the light guide plate 10. This can reduce uneven brightness and color in the first main surface 11, which is the light emitting surface of the light emitting module 1.

[0064] Figure 3 yes Figure 1 B-B section diagram in.

[0065] Figure 4 It is a perspective view of the elements (the light scattering layer 31 , the phosphor layer 22 , and the light-transmitting portion 60 ) in the recess 15 of the light guide plate 10 in the light emitting module 1 according to the embodiment.

[0066] The shape of the opening 16 of the recess 15 is, for example, a quadrangle, and the shape of the opening 16 of the recess 15 is different from the shape of the bottom surface 17 of the recess 15 .

[0067] The recess 15 has an inclined surface 18 inclined at an obtuse angle with respect to the bottom surface 17 of the recess 15. The light-transmitting portion 60 is in contact with the inclined surface 18 of the recess 15 and has an inclined surface 61 facing the inclined surface 18 of the recess 15.

[0068] In addition, if Figure 2 and Figure 4As shown, the light-transmitting portion 60 has an upper surface 63 in contact with the bottom surface 17 of the recess 15 and a vertical surface 62 perpendicular to the bottom surface 17 of the recess 15. The vertical surface 62 is also in contact with the light guide plate 10.

[0069] In the light-transmitting portion 60, the contact area with the light guide plate 10 can be expanded by forming the inclined surface 61, compared with the case where the surfaces in contact with the light guide plate 10 are only the upper surface 63 and the vertical surface 62. That is, the boundary surface between different materials can be expanded, and the light emitted from the fluorescent layer 22 can be easily taken into the light guide plate 10 from the light-transmitting portion 60.

[0070] In addition, Figure 1 In the top view shown, the inclined surface 61 is located between the corner 11a of the first main surface 11 and the side surface 22a of the fluorescent layer 22, and is located opposite to the corner 11a of the first main surface 11. Therefore, the light emitted from the fluorescent layer 22 can be easily diffused to the four corners of the first main surface 11 of the light guide plate 10 via the inclined surface 61 of the light-transmitting portion 60, and the brightness unevenness and color unevenness in the first main surface 11 can be reduced.

[0071] Figure 5 Schematic diagram of the boundary surface between the light guide plate 10 and the light-transmitting portion 60 .

[0072] By providing the inclined surface 61 on the light-transmitting portion 60, the light emitted from the light source 20 easily advances in the diffusion direction by utilizing the refractive index difference between the light-transmitting portion 60 and the light guide plate 10. This can prevent the area immediately above the light source 20 from being too bright compared to other areas on the first principal surface 1 of the light guide plate 10, and can reduce uneven brightness and color. In the case where the light-transmitting portion 60 is a gap (air layer), the light emitted from the light source 20 also easily advances in the diffusion direction by utilizing the refractive index difference with the light guide plate 10.

[0073] Figure 6A to Figure 6C It is a schematic cross-sectional view showing a method for manufacturing the light emitting module 1 according to the embodiment.

[0074] First, if Fig. 6A As shown, prepare the light guide plate 10. The light guide plate 10 can be formed by, for example, injection molding, transfer molding, thermal transfer, etc. By molding the recessed portion 19 provided with the optical function portion 32 and the recessed portion 15 provided with the fluorescent layer 22 together with a mold, the alignment accuracy of the optical function portion 32 and the light emitting element 21 can be improved.

[0075] like Figure 6B As shown, for example, a light-transmitting resin is supplied to the recessed portion 15 as the light-transmitting portion 60. The light-transmitting resin is supplied to the recessed portion 15 in a liquid or fluid state by a method such as potting, printing, or spraying.

[0076] After the light-transmitting portion 60 is supplied to the concave portion 15, as shown in FIG. Figure 6C As shown, the light source 20 is disposed in the recess 15 together with the light scattering layer 31. The light scattering layer 31 is bonded to the bottom surface 17 of the recess 15.

[0077] The light scattering layer 31, the phosphor layer 22, and the light emitting element 21 are integrated in a mutually bonded state and supplied to the recess 15. At this time, the phosphor layer 22, which is quadrangular in plan view, is self-adjustably positioned in such a manner that its side surface 22a is along the long side 17a of the bottom surface 17 of the recess 15. Therefore, the light emitting element 21 is also self-adjustably positioned relative to the light guide plate 10. In addition, since the area of ​​the opening 16 of the recess 15 is larger than the area of ​​the bottom surface 17, it is easy to supply the light scattering layer 31 and the phosphor layer 22 into the recess 15.

[0078] Then, the concave portion 19 on the first main surface 11 side of the light guide plate 10 is provided. Figure 2 The light reflective resin portion 40 is provided on the optical function portion 32 shown in the figure so as to cover the inclined surface 14 and the second main surface 12 of the light guide plate 10. Under the light reflective resin portion 40, a wiring substrate 50 is bonded.

[0079] In the light emitting module 1 of the embodiment, since the light emitting element 21 is mounted on the light guide plate 10 instead of the wiring substrate 50, the distance between the light guide plate 10 and the light emitting element 21 can be shortened, and the light emitting module 1 can be made thinner. Such a light emitting module 1 can be used, for example, for a backlight of a liquid crystal display. For example, in a direct-type liquid crystal display in which the backlight is arranged on the back of the liquid crystal panel, since the distance between the liquid crystal panel and the light emitting module 1 is close, the unevenness of the brightness or color of the light emitting module 1 is likely to affect the unevenness of the brightness or color of the liquid crystal display. By using the light emitting module 1 with less uneven brightness or color as in the embodiment as the backlight of the direct-type liquid crystal display, the unevenness of the brightness or color of the liquid crystal display can be reduced.

[0080] Figure 7 2 is a schematic top view of a light emitting module 100 according to another embodiment.

[0081] The light emitting module 100 includes a light guide plate 10 and a plurality of units 2 periodically arranged on the light guide plate 10. One unit 2 has the same structure as the light emitting module 1 described above.

[0082] That is, a plurality of optical function parts 32 are provided on the first principal surface 11 side of one light guide plate 10, and a plurality of recesses 15 are formed on the second principal surface 12. In the recesses 15, the light scattering layer 31, the light source 20, and the light transmitting part 60 are arranged.

[0083] Figure 7This is a top view of the first main surface 11 of the light guide plate 10. In this top view, one unit 2 is formed into, for example, a quadrilateral having four corners 2a. Each unit 2 is arranged in such a way that its side is along the side of the quadrilateral first main surface 11 of the light guide plate 10. Moreover, in a top view, the long side 17a of the bottom surface 17 of the recess 15 of each unit 2 and the side surface 22a of the light source (the side surface 22a of the phosphor layer 22) face the corner 2a of each unit 2. The diagonal line connecting the corners 2a of one unit 2 intersects with the long side 17a of the bottom surface 17 of the recess 15 of the unit 2. The diagonal line connecting the corners 2a of one unit 2 intersects with the side surface 22a of the phosphor layer 22 of the unit 2.

[0084] Therefore, in each unit 2, light emitted from the phosphor layer 22 is easily diffused to the four corners of the unit 2. On the light-emitting surface of the light-emitting module 100, that is, the entire first main surface 11, the brightness concentration in the center of each unit 2 can be suppressed, and the brightness and color unevenness within the light-emitting surface of the light-emitting module 100 can be reduced.

[0085] Above, the embodiments of the present invention have been described with reference to specific examples. However, the present invention is not limited to these specific examples. All modes that can be implemented by those skilled in the art based on the above-mentioned embodiments of the present invention by appropriately designing changes, as long as they include the gist of the present invention, also belong to the scope of the present invention. In addition, it should be understood that those skilled in the art can think of various variations and modifications within the scope of the idea of ​​the present invention, and these variations and modifications also belong to the scope of the present invention.

Claims

1. A light emitting module, characterized in that: have: A light guide plate having a polygonal shape with a plurality of corners when viewed from above, and comprising: a first main surface serving as a light emitting surface, a second main surface opposite to the first main surface, and a recessed portion provided on the second main surface; a light source disposed in the recess, The recess has an opening on the second main surface side and a bottom surface that is polygonal in plan view. The bottom surface has four long sides and four short sides shorter than the long sides. The light source has a side surface along the long side of the bottom surface of the recessed portion, In a plan view, a diagonal line connecting the plurality of corners of the first main surface and the long side of the bottom surface of the recess intersect.

2. The light emitting module according to claim 1, characterized in that: In a plan view, a diagonal line connecting the plurality of corners of the first main surface intersects the side surface of the light source.

3. The light emitting module according to claim 1, characterized in that: A plurality of units each including the concave portion and the light source and having a quadrangular shape when viewed from above are periodically arranged on one of the light guide plates, In a plan view, the side portions of the bottom surface of the recessed portion of each of the units and the side surfaces of the light source face toward the corners of each of the units.

4. The light emitting module according to claim 1, characterized in that: The recess has an inclined surface inclined at an obtuse angle to the bottom surface.

5. The light emitting module according to claim 4, characterized in that: The invention further includes a light-transmitting portion provided around the light source in the recessed portion, wherein the light-transmitting portion is in contact with the inclined surface.

6. The light emitting module according to claim 5, characterized in that: The light-transmitting portion is a light-transmitting resin portion.

7. The light emitting module according to claim 6, characterized in that: The refractive index of the light-transmitting resin portion is lower than the refractive index of the light guide plate.

8. The light emitting module according to claim 1, characterized in that: An area of ​​the opening of the recessed portion is larger than an area of ​​the bottom surface of the recessed portion.

9. The light emitting module according to claim 1, characterized in that: An optical function portion is further provided, the optical function portion being provided at a position of the first main surface of the light guide plate facing the recessed portion and having a refractive index lower than that of the light guide plate.

10. The light emitting module according to claim 1, characterized in that: The light source includes a light emitting element and a phosphor layer bonded to a main light emitting surface of the light emitting element.

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