WO2018221657A1

WO2018221657A1 - Spacer, led surface light source device, and led image display device

Info

Publication number: WO2018221657A1
Application number: PCT/JP2018/020969
Authority: WO
Inventors: 直信喜; 健森長; 松浦　大輔
Original assignee: 大日本印刷株式会社
Priority date: 2017-06-01
Filing date: 2018-05-31
Publication date: 2018-12-06
Also published as: JPWO2018221657A1; JP2019194985A; TW201911557A; JP6575729B2; JP6575718B1

Abstract

One aspect of the present invention provides a first spacer (60) that is used in an LED surface light source device (20) which is provided with a first optical sheet (50) and an LED mounting substrate (40) facing the first optical sheet (50). The first spacer is disposed between the first optical sheet (50) and the LED mounting substrate (50) and separates the first optical sheet (50) from the LED mounting substrate (40). The first spacer (60) is provided with: at least two openings (61) that penetrate in the height direction of the first spacer; and a wall part (62) that surrounds the periphery of at least one of the openings (61) and that has a partition part (64) that partitions the openings (61) from each other. The partition part (64) has two side surfaces that face the openings and includes a thermally curable resin. The light transmittance from one side surface (64A) to another side surface (64A) of the partition part (64) is 30% or less.

Description

Spacer, LED surface light source device and LED image display device

Reference to related applications

This application enjoys the benefit of priority of Japanese Patent Application No. 2017-109304 (filing date: June 1, 2017), which is a preceding Japanese application, the entire disclosure of which is incorporated herein by reference. To be part of

The present invention relates to a spacer, an LED surface light source device, and an LED image display device.

2. Description of the Related Art In recent years, LED image display devices that have rapidly spread are usually provided with a display screen such as a liquid crystal display panel and an LED surface light source device that illuminates the display screen from the back side. Currently, edge-light type LED surface light source devices are often used in LED image display devices, but from the viewpoint of brightness, the use of direct type LED surface light source devices has been studied.

In the direct type LED surface light source device, an optical sheet is disposed on the LED element from the viewpoint of improving the in-plane uniformity of luminance on the light emitting surface of the LED surface light source device. As such an optical sheet, for example, a white or other resin-made reflective material sheet that reflects light from the LED element has an opening pattern in which the opening gradually increases as it goes from directly above the LED element to the periphery of the LED element. There is a case where a formed light transmitting / reflecting sheet is used (see JP 2010-272245 A). By using a light-transmitting / reflecting sheet having such an opening pattern, the light directly above the LED element can be reflected and diffused to the surroundings and emitted from the surrounding openings, improving the in-plane uniformity of luminance. Can be made.

In order to improve the in-plane uniformity of luminance by the optical sheet, it is necessary to separate the optical sheet from the LED mounting substrate on which the LED elements are mounted. For this reason, usually, a plurality of columnar spacers for separating the optical sheet from the LED mounting substrate are arranged between the LED mounting substrate and the optical sheet.

However, when columnar spacers are used, the optical sheet may be bent between the spacers. When a light transmitting / reflecting sheet is used as the optical sheet, if the light transmitting / reflecting sheet is bent, the position of the opening pattern with respect to the LED element is changed, so that in-plane uniformity of luminance may be lowered.

Currently, local dimming control is known in which LED elements are individually controlled so as to correspond to light and dark portions of an image to reduce power consumption and improve contrast.

In local dimming control, it is required that the light from the LED elements is not mixed with each other. However, when columnar spacers are used, light escapes from the gaps between the spacers, so that the light from the LED elements is mixed with each other. End up.

The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a spacer that can suppress the bending of the optical sheet and is suitable for local dimming control, and an LED surface light source device and an LED image display device including the spacer.

According to one aspect of the present invention, an LED including a wiring board, an LED mounting board including a plurality of LED elements mounted on one surface of the wiring board, and an optical sheet disposed on the LED element side. A spacer that is used in a surface light source device and is disposed between the LED mounting substrate and the optical sheet and separates the optical sheet from the LED mounting substrate, and penetrates in the height direction of the spacer. Two openings having the above-described opening and a wall having a partition for partitioning between the openings and surrounding at least one of the openings, the partition facing the opening There is provided a spacer that includes a thermoplastic resin and has a light transmittance of 30% or less from one side surface to the other side surface of the partition.

In the spacer, the partition may further include a light shielding material present in the thermoplastic resin.

In the spacer, the partition portion may include a partition portion main body including the thermoplastic resin and a light shielding layer provided on at least one side surface of the partition portion main body.

In the spacer, the partition portion includes a partition portion body including the thermoplastic resin and a light shielding layer, and the partition portion body includes a first portion including a first side surface of the partition portion body, and A partition portion main body including a second side opposite to the first side and the second portion spaced apart from the first portion, wherein the light shielding layer includes the first portion and the first portion; It may be sandwiched between the second part.

In the spacer, the arithmetic average roughness of at least one side surface of the partition may be 10 μm or less.

In the spacer, the wall portion may have a lattice shape or a honeycomb shape.

According to another aspect of the present invention, a wiring board, an LED mounting board comprising a plurality of LED elements mounted on one surface of the wiring board, and a first optical sheet disposed on the LED element side, A first spacer disposed between the LED mounting substrate and the first optical sheet, and separating the first optical sheet from the LED mounting substrate, and the first spacer, An LED surface light source device that is the spacer is provided.

In the LED surface light source device, a side surface of the spacer facing the opening of the wall is inclined so that an opening diameter of the opening increases from the wiring board toward the first optical sheet. You may do it.

In the LED surface light source device, the first optical sheet includes a plurality of divided regions in plan view, and each of the divided regions transmits a part of light from the LED element. And a plurality of reflecting portions that reflect a part of the light from the LED element, and an aperture ratio that is an area ratio of the transmission portion in each partition region is from the central portion of the partition region to the partition region A region that gradually increases toward the outer edge of the substrate may be included.

In the LED surface light source device, the thickness of the first optical sheet may be not less than 25 μm and not more than 1 mm.

In the LED surface light source device, the second optical sheet disposed on the light emitting side of the first optical sheet, the outer peripheral surface of the first optical sheet, and the outer peripheral surface of the first spacer are surrounded. And a frame-shaped second spacer that is disposed and supports the second optical sheet.

According to another aspect of the present invention, there is provided an LED image display device comprising the LED surface light source device and a display panel disposed closer to an observer than the LED surface light source device.

According to one aspect of the present invention, it is possible to provide a spacer that can suppress the bending of the optical sheet and is suitable for local dimming control. Moreover, according to the other aspect of this invention, an LED surface light source device and LED image display apparatus provided with such a spacer can be provided.

FIG. 1 is an exploded perspective view of an LED image display device according to an embodiment. FIG. 2 is a schematic configuration diagram of the LED image display device according to the embodiment. FIG. 3 is an enlarged cross-sectional view of a part of the LED surface light source device according to the embodiment. FIG. 4 is a plan view of the first optical sheet shown in FIG. FIG. 5 is a plan view of another first optical sheet according to the embodiment. FIG. 6 is a plan view of the first spacer shown in FIG. FIG. 7 is a plan view showing the positional relationship between the first optical sheet and the first spacer shown in FIG. FIG. 8 is a plan view of another first spacer according to the embodiment. FIG. 9 is a plan view of another first spacer according to the embodiment. FIG. 10 is a plan view of another first spacer according to the embodiment. FIG. 11A and FIG. 11B are plan views of other first spacers according to the embodiment. FIG. 12 (A) is a diagram schematically showing a state in which a sample for measuring the light transmittance between the side surfaces is cut out from the partition portion of the first spacer, and FIG. 12 (B) and FIG. 12 (C). These are the figures which showed typically the mode at the time of measuring the light transmittance between the side surfaces of a sample. FIG. 13A and FIG. 13B are longitudinal sectional views of a part of another first spacer according to the embodiment. FIG. 14A and FIG. 14B are longitudinal sectional views of a part of another first spacer according to the embodiment. FIG. 15A and FIG. 15B are longitudinal sectional views of a part of another first spacer according to the embodiment. FIG. 16 is a plan view showing the positional relationship between the first spacer and the second spacer shown in FIG. FIG. 17 is a cross-sectional view of the lens sheet shown in FIG.

Hereinafter, a spacer, a direct type LED surface light source device, and an LED image display device according to embodiments of the present invention will be described with reference to the drawings. In this specification, “LED” means a light emitting diode. Further, terms such as “sheet”, “film”, and “plate” are not distinguished from each other based only on the difference in designation. Therefore, for example, “sheet” is used to include a member called a film or a plate. FIG. 1 is an exploded perspective view of an LED image display device according to the present embodiment, FIG. 2 is a schematic configuration diagram of the LED image display device according to the present embodiment, and FIG. 3 is an LED surface light source device according to the present embodiment. FIG. 4 is a plan view of the first optical sheet shown in FIG. 1, FIG. 5 is a plan view of another first optical sheet according to the embodiment, and FIG. 6 is a plan view of the first optical sheet shown in FIG. FIG. 7 is a plan view showing the arrangement relationship between the first optical sheet and the first spacer shown in FIG. FIGS. 8 to 11 are plan views of other first spacers according to the embodiment, and FIG. 12A shows a sample for measuring the light transmittance between the side surfaces cut out from the partition portion of the first spacer. It is the figure which showed the mode typically, and FIG. 12 (B) and FIG.12 (C) are the figures which showed typically the mode at the time of measuring the light transmittance between the side surfaces of a sample. 13 to 15 are longitudinal sectional views of a part of another first spacer according to the embodiment, and FIG. 16 is a plan view showing the positional relationship between the first spacer and the second spacer shown in FIG. FIG. 17 is a cross-sectional view of the lens sheet shown in FIG.

<<<<< LED image display device >>>>
The LED image display device 10 shown in FIGS. 1 and 2 includes a direct-type LED surface light source device 20 and a display panel 120 disposed closer to the viewer than the LED surface light source device 20.

<<< Display Panel >>>
The display panel 120 shown in FIGS. 1 and 2 is a liquid crystal display panel, and includes a polarizing plate 121 disposed on the light incident side, a polarizing plate 122 disposed on the light exit side, a polarizing plate 121 and a polarizing plate 122. And a liquid crystal cell 123 disposed between them. As the

polarizing plates

121 and 122 and the liquid crystal cell 123, known polarizing plates and liquid crystal cells can be used.

<<< LED surface light source device >>>
The LED surface light source device 20 shown in FIG. 1 or 2 includes a housing 30, an LED mounting substrate 40, a first optical sheet 50, a first spacer 60, a second optical sheet 70, 2 spacers 80. In addition, the LED surface light source device 20 includes a lens sheet 90 and a reflective polarization separation sheet 100 laminated on the second optical sheet 70. Note that the LED surface light source device 20 only needs to include the LED mounting substrate 40, the first optical sheet 50, and the first spacer 60, and the housing 30, the second optical sheet 70, and the second spacer 80. The lens sheet 90 or the reflective polarization separation sheet 100 may not be provided.

When the LED surface light source device is used for in-vehicle use, it is disposed in a very narrow space in the vehicle, so that it is desired to make it thinner than a general LED surface light source device. For this reason, the total thickness of the LED surface light source device 20 is preferably 15 mm or less, and more preferably 10 mm or less, from the viewpoint of reducing the thickness. The total thickness of the “LED surface light source device” means the distance from the outer bottom surface 30 C of the housing 30 shown in FIG. 2 to the surface 100 A of the reflective polarization separation sheet 100.

<< Case >>
The housing 30 includes a housing space 30A for housing the LED mounting substrate 40 and the like. As shown in FIG. 2 or 3, the housing 30 has an inner bottom surface 30B that is an inner bottom surface, an outer bottom surface 30C that is an outer bottom surface, and an inner side surface 30D that is an inner side surface rising from the inner bottom surface 30B. is doing. Moreover, the housing | casing 30 has the opening part 30E for making the light from the LED element 42 radiate | emit from the housing | casing 30, as FIG. 2 shows. The opening 30E is preferably provided at a position facing the inner bottom surface 30B. The shape of the opening 30E is not particularly limited, and examples thereof include a rectangular shape or a circular shape.

The housing 30 shown in FIGS. 1 and 2 includes a housing body 31 having a housing space 30A, and a frame-shaped lid 32 that covers the housing space 30A of the housing body 31 and has an opening 30E. ing. In the housing 30, the inner bottom surface 30 B of the housing 30 is the inner bottom surface of the housing body 31, and the inner side surface 30 D of the housing 30 is the inner side surface of the housing body 31.

The housing 30 (the housing body 31 and the lid body 32) is preferably made of metal. By constituting the casing body 31 from metal, the casing body 31 also functions as a heat dissipation structure, so that the heat from the LED element 42 can be efficiently radiated. Although it does not specifically limit as a metal, For example, aluminum etc. are mentioned.

<< LED mounting board >>
The LED mounting substrate 40 includes a wiring substrate 41 and a plurality of LED elements 42 mounted on one surface (hereinafter referred to as “surface”) 41 A of the wiring substrate 41. 2 and 3, the LED mounting board 40 has a surface 41B opposite to the front surface 41A on which the LED element 42 is mounted on the wiring board 41 (hereinafter, this surface is referred to as "back surface") 41B. The housing 30 is disposed in the housing 30 so as to be positioned on the inner bottom surface 30B side.

<Wiring board>
The wiring board 41 is disposed along the inner bottom surface 30 B of the housing 30. The back surface 41B of the wiring board 41 is preferably in contact with the inner bottom surface 30B of the housing 30. Since the back surface 41B of the wiring board 41 is in contact with the inner bottom surface 30B of the housing 30, the heat of the wiring substrate 41 and the like can be efficiently radiated to the housing 30 side. In this specification, “the back surface of the wiring board is in contact with the inner bottom surface of the housing” is not limited to the case where the back surface of the wiring board is in direct contact with the inner bottom surface of the housing. This is a concept that includes a case where a layer that can be almost ignored in terms of heat conduction, such as a double-sided tape, an adhesive, or an adhesive, is interposed between the inner bottom surface of the housing.

In the wiring board 41, as shown in FIG. 3, the resin film 43, the metal wiring part 44, the insulating protective film 45, and the reflective layer 46 are arranged in this order toward the first optical sheet 50. Are stacked. However, the wiring board 41 may not include the insulating protective film 45 and the reflective layer 46. The metal wiring part 44 is preferably bonded to the resin film 43 by a dry laminating method through an adhesive layer 47. Further, the metal wiring portion 44 is electrically connected to the LED element 42 via the solder layer 48.

The wiring board 41 may be a rigid wiring board, but is preferably a flexible wiring board. Since the wiring board 41 is a flexible wiring board, a bendable LED surface light source device can be obtained. A wiring board 41 shown in FIG. 2 is a flexible wiring board. “Flexible” means that there is flexibility, and “flexible wiring board” means a wiring board that is generally flexible and can be bent. The term “flexibility” in this specification means bending so that the radius of curvature is at least 1 m. The flexible wiring board is bent so that the radius of curvature is preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, and particularly preferably 5 cm.

(Resin film)
The resin film 43 has flexibility. The resin film 43 is a film that bends so that the radius of curvature is preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, and particularly preferably 5 cm.

The resin film 43 can be formed using a known thermoplastic resin. The thermoplastic resin used as the material of the resin film 43 preferably has high heat resistance and insulation. As such a resin, polyimide (PI) or polyethylene naphthalate (PEN) which is excellent in heat resistance, dimensional stability during heating, mechanical strength, and durability can be used. Further, polyethylene terephthalate (PET) whose flame retardancy is improved by addition of a flame retardant inorganic filler or the like can also be selected as a resin for forming a resin film.

As the thermoplastic resin for forming the resin film 43, one having a thermal shrinkage start temperature of 100 ° C. or higher, or one having improved heat resistance so that the temperature becomes 100 ° C. or higher by the above-described annealing treatment or the like is used. It is preferable. In this specification, “thermal shrinkage start temperature” means that a sample film made of a thermoplastic resin to be measured is set in a thermomechanical analysis (TMA) apparatus, a load of 1 g is applied, and a temperature rise rate of 2 ° C./min is 120. Measure the amount of shrinkage (in%) at that time, measure the temperature and the amount of shrinkage, and read the temperature that deviates from the 0% baseline due to shrinkage. Is the heat shrinkage start temperature. The heat shrinkage starting temperature is an arithmetic average value obtained by measuring three times.

Usually, the LED element periphery may reach a temperature of about 90 ° C. due to heat from the LED element. From this viewpoint, it is preferable that the thermoplastic resin forming the resin film 43 has heat resistance equal to or higher than the above temperature.

The resin film 43 is required to be a resin having high insulation enough to provide the wiring board 41 with necessary insulation. For this reason, the resin film 43 has a volume resistivity of preferably 10 ¹⁴ Ω · cm or more, and more preferably 10 ¹⁸ Ω · cm or more. The volume resistivity can be measured by a method based on JIS C2151: 2006. The volume resistivity is measured at 10 random locations, and is the arithmetic average value of the measured volume resistivity at 10 locations.

The thickness of the resin film 43 is not particularly limited, but is generally 10 μm or more and 500 μm or less from the viewpoint of not being a bottleneck as a heat dissipation path, having heat resistance and insulation, and a balance of manufacturing costs. It is preferable that Moreover, it is preferable that it is the said thickness range also from a viewpoint of maintaining favorable productivity at the time of manufacturing by a roll-to-roll system. The thickness of the resin film 43 is determined by measuring the thickness at any 10 locations using a thickness measuring device (product name “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation) and calculating the average value. Shall. The lower limit of the thickness of the resin film 43 is preferably 10 μm or more, and the upper limit of the thickness of the resin film 43 is preferably 250 μm or less.

(Metal wiring part)
The metal wiring portion 44 is provided closer to the LED element 42 than the resin film 43 and is electrically connected to the LED element 42. The metal wiring part 44 can be formed by patterning a metal foil or the like.

The thermal conductivity λ of the metal constituting the metal wiring part 44 is preferably 200 W / (m · K) or more and 500 W / (m · K) or less. The thermal conductivity λ can be measured using, for example, a thermal conductivity meter (product name “QTM-500”, manufactured by Kyoto Electronics Industry Co., Ltd.). The thermal conductivity λ is an arithmetic average value obtained by measuring three times. The lower limit of the thermal conductivity is more preferably 300 W / (m · K) or more, and the upper limit is preferably 500 W / (m · K) or less. In the case of copper, the thermal conductivity λ is 403 W / (m · K).

The electric resistivity R of the metal constituting the metal wiring portion 44 is preferably 3.00 × 10 ⁻⁸ Ωm or less, and more preferably 2.50 × 10 ⁻⁸ Ωm or less. The electrical resistivity R can be measured using an electrometer (product name “6517B type electrometer”, manufactured by Keithley). The electrical resistivity R is an arithmetic average value of values obtained by measuring three times. In the case of copper, the electrical resistivity R is 1.55 × 10 ⁻⁸ Ωm.

For example, when the metal wiring part 44 is formed of a copper foil, both heat dissipation and electrical conductivity can be achieved at a high level. More specifically, since the heat dissipation from the LED elements is stabilized and an increase in electrical resistance can be prevented, the light emission variation between the LED elements is reduced, and the LED elements can stably emit light. In addition, the lifetime of the LED element is extended. Further, since deterioration of peripheral members such as a resin film due to heat can be prevented, the product life of the LED image display device incorporating the LED surface light source device can be extended.

Examples of the metal forming the metal wiring part 44 include metals such as aluminum, gold, and silver in addition to the above copper.

The metal wiring part 44 is an electrolytic copper foil, and the ten-point average roughness Rz of the surface on the resin film 43 side in the metal wiring part 44 is more preferably 1.0 μm or more and 10.0 μm or less. By setting the ten-point average roughness Rz within the above range, the surface area of the surface of the metal wiring portion 44 on the resin film 43 side can be increased, and the heat dissipation can be further enhanced. Moreover, since this surface is a concavo-convex surface, the adhesiveness with the resin film 43 can be further improved, and thereby the heat dissipation can be improved. As the surface of the electrolytic copper foil having such a ten-point average roughness Rz, the rough surface side (mat surface side) of the electrolytic copper foil can be suitably used. The ten-point average roughness Rz can be measured, for example, using a surface roughness measuring instrument (product name “SE-3400”, manufactured by Kosaka Laboratory) in accordance with JIS B0601: 1999. The ten-point average roughness Rz is an arithmetic average value obtained by measuring three times.

The arrangement of the metal wiring part 44 is not limited to a specific arrangement as long as the LED elements 42 can be conducted, preferably the LED elements 42 can be arranged in a matrix. However, in the wiring substrate 41, the surface of one surface of the resin film 43 is preferably 80% or more, more preferably 90%, and most preferably 95% or more is covered with the metal wiring part 44. preferable. Accordingly, the LED elements 42 can be arranged with high density, and the excessive heat generated can be sufficiently diffused quickly through the metal wiring portion 44 and radiated to the outside via the resin film 43. Therefore, the LED surface light source device 20 which has the outstanding heat dissipation can be obtained.

The thickness of the metal wiring portion 44 may be set as appropriate according to the magnitude of the withstand current required for the wiring substrate 41 and is not particularly limited, but may be 10 μm or more and 50 μm or less as an example. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 44 is preferably 10 μm or more. In addition, if the thickness of the metal wiring portion is less than 10 μm, the influence of heat shrinkage of the resin film 43 is large, and warpage after the processing is likely to increase during the solder reflow processing. The thickness is preferably 10 μm or more. On the other hand, when the thickness of the metal wiring portion is 50 μm or less, it is possible to maintain sufficient flexibility of the wiring substrate, and it is possible to prevent a decrease in handling properties due to an increase in weight. The thickness of the metal wiring portion 44 can be measured by the same method as that for the resin film 43.

(Insulating protective film)
The insulating protective film 45 mainly improves the migration resistance characteristics of the wiring board 41. The insulating protective film 45 covers the entire surface of the surface of the metal wiring portion 44 except for the connection portion for mounting the LED element 42 and the substantially entire surface of the surface of the resin film 43 where the metal wiring portion 44 is not formed. It is formed in an embodiment.

The insulating protective film 45 is preferably composed of a cured product of a thermosetting resin composition containing a thermosetting resin. As the thermosetting resin composition, a known thermosetting resin composition can be suitably used as long as the thermosetting temperature is about 100 ° C. or less. Specifically, a thermosetting resin composition using a polyester resin, an epoxy resin, an epoxy resin and a phenol resin, an epoxy acrylate resin, a silicone resin, or the like as a base resin can be preferably used. Among these, a thermosetting resin composition containing a polyester-based resin is particularly preferable as a material for forming the insulating protective film 45 from the viewpoint of excellent flexibility.

The thermosetting resin composition for forming the insulating protective film 45 may be a white thermosetting resin composition further containing an inorganic white pigment such as titanium dioxide, for example. By whitening the insulating protective film 45, the design can be improved. Further, the function of the reflective layer can be imparted to the insulating protective film 45.

The formation of the insulating protective film 45 using the insulating thermosetting resin composition can be performed by a known method such as screen printing.

The film thickness of the insulating protective film 45 is preferably 10 μm or more and 100 μm or less. If the thickness of the insulating protective film 45 is less than 10 μm, the insulating property may be lowered, and if it exceeds 100 μm, bleeding when forming the insulating protective layer by screen printing or shrinkage during thermosetting There is a possibility that the warping of the wiring board due to the above will occur remarkably. As for the film thickness of the insulating protective film 45, a cross section of the insulating protective film 45 is photographed using a scanning electron microscope (SEM), and the film thickness of the insulating protective film 45 is measured at 20 locations in the image of the cross section. The arithmetic average value of the film thicknesses at the 20 locations is used.

(Reflective layer)
The reflective layer 46 has high reflectivity mainly with respect to light in a visible light wavelength region having a wavelength of 380 nm to 780 nm. The reflective layer 46 is laminated on the surface 41 A of the wiring board 41 so as to cover a region excluding the LED element mounting region for the purpose of improving the light emission capability of the LED surface light source device 20. In this embodiment, the reflection layer 46 is insulated so as to surround the LED element 42 in a plan view and to expose the inner peripheral edge of the region removed by the LED element mounting region of the insulating protective film 45. On the protective protective film 45. In addition, for example, the inner peripheral edge of the region of the insulating protective film 45 that is removed by the LED element mounting region is not exposed, and the inner peripheral edge of both the insulating protective film 45 and the reflective layer 46 is not exposed. They may be laminated so as to match and form the same shape.

The reflection layer 46 is not particularly limited as long as it is a member having a reflection surface for reflecting the light from the LED element 42 and guiding it in a predetermined direction. For example, foam type white polyester, white polyethylene resin, silver-deposited polyester, etc. Can be appropriately used according to the use of the final product and the required specifications.

The film thickness of the reflective layer 46 is preferably 50 μm or more and 1 mm or less. If the thickness of the reflective layer 46 is less than 50 μm, the desired reflectance may not be obtained, and since the reflective layer is too thin, it is difficult to set in a predetermined position. In addition to the cost, the LED surface light source device may not be thinned. The thickness of the reflective layer 46 can be measured by the same method as the thickness of the insulating protective film 45.

(Adhesive layer)
As the adhesive layer 47, a known resin adhesive can be used as appropriate. Of these resin-based adhesives, urethane-based, polycarbonate-based, or epoxy-based adhesives can be particularly preferably used. The adhesive layer 47 remains on the resin film 43 after the metal wiring portion 44 is etched.

(Solder layer)
The solder layer 48 is for electrically and mechanically joining the metal wiring part 44 and the LED element 42. As a joining method using the solder layer 48, there are a reflow method and a laser method, which can be performed by either of them.

When joining the metal wiring part and the LED element with solder, a great amount of heat is applied to the resin film and the metal wiring part. Therefore, the resin film and the metal wiring part are affected by the difference in coefficient of linear expansion between the resin film and the metal wiring part. There is a risk of warping of the wiring board provided with. In order to prevent such warpage, it is preferable to provide a metal foil on the surface of the resin film 43 opposite to the surface on the metal wiring portion 44 side. Further, by providing such a metal foil, the heat of the LED mounting substrate 40 at the time of lighting can be further radiated to the housing body 31.

<< LED element >>
The LED element 42 is a light emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. As LED elements, there are known a structure in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element, and a structure in which both the P-type and N-type electrodes are provided on one side of the element. An LED element can also be used for the LED surface light source device 20. However, an LED element having a structure in which both P-type and N-type electrodes are provided on one side of the element can be particularly preferably used.

The LED elements 42 are arranged in a matrix on the wiring board 41. The “matrix shape” in this specification means a state in which the matrix is two-dimensionally arranged. In the present embodiment, the LED elements 42 are arranged in a matrix, but the arrangement state of the LED elements is not particularly limited. For example, the LED elements may be arranged in a staggered manner. A plurality of LED elements 42 are mounted on the wiring board 41. The number of LED elements 42 mounted on the wiring board 41 is not particularly limited as long as it is plural. The arrangement density of the LED elements 42 is preferably 0.02 pieces / cm ² or more and 2.0 pieces / cm ² or less, and preferably 0.1 pieces / cm ² or more and 1.5 pieces / cm ² or less. More preferred.

<< first optical sheet >>
The first optical sheet 50 is a sheet having an optical function. Examples of the first optical sheet include a light transmission / reflection sheet. The first optical sheet 50 shown in FIGS. 1 and 2 is a light transmission / reflection sheet. The light-transmitting / reflecting sheet has a transmitting part that transmits light and a reflecting part that reflects light, and transmits light in one part and reflects light in another part, thereby allowing light from the LED element to be in a plane. And having a function of improving the in-plane uniformity of luminance.

The first optical sheet 50 is disposed on the LED element 42 side. Specifically, the first optical sheet 50 is disposed so as to face the plurality of LED elements 42, and is separated from the LED mounting substrate 40 by the first spacer 60. The first optical sheet 50 is disposed substantially parallel to the wiring board 41.

The distance d1 from the surface 41A of the wiring board 41 shown in FIG. 3 to the first optical sheet 50 is 0.6 mm or more and 6 mm or less. In this specification, the “distance from the surface of the wiring board to the first optical sheet” includes a reflective layer on the insulating protective layer like the wiring board 41, and the surface of the reflective layer is the surface of the wiring board. Means the distance from the surface of the reflective layer to the surface of the first optical sheet on the side of the wiring board, and the insulating protective layer of the wiring board also has the function of the reflective layer, When the surface of the protective protective layer is the surface of the wiring substrate, it means the distance from the surface of the insulating protective layer to the surface on the wiring substrate side of the first optical sheet. The surface on the wiring board side in the first optical sheet is the surface on the wiring board side in the resin film when the surface on the wiring board side in the first optical sheet is composed only of the surface of the resin film. However, when the reflective layer 55 is formed on the wiring substrate 41 side of the resin film 54 as in the first optical sheet 50, the surface of the reflective layer 55 on the wiring substrate 41 side is used.

The thickness of the first optical sheet 50 is preferably 25 μm or more and 1 mm or less. If the thickness of the light transmitting / reflecting sheet is less than 25 μm, the desired reflectance may not be obtained, and if it exceeds 1 mm, the LED surface light source device may not be thinned. The thickness of the first optical sheet 50 is the thickness of the reflecting portion 53 to be described later, and the thickness is measured at any 10 locations using a thickness measuring device (product name “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation). It can be obtained by measuring the thickness and calculating the average value. As shown in FIG. 4, the first optical sheet 50 includes a partitioned area 51 that is divided into a plurality of parts in plan view.

<Division area>
The partition area 51 is preferably divided according to the number of the LED elements 42. In FIG. 4, 4 vertical sections × 6 horizontal sections = 24 partition areas 51 are formed corresponding to the LED elements (4 vertical sections × 6 horizontal sections = 24). In FIG. 4, the boundary line is indicated by a dotted line. However, the boundary line is not actually formed, the boundary line is a virtual line, and the partition area 51 is also a virtual area.

As shown in FIG. 4, each partition region 51 includes a plurality of transmission parts 52 that transmit a part of the light from the LED element 42, and a plurality of reflection parts 53 that reflect a part of the light from the LED element 42. It consists of The transmission part 52 and the reflection part 53 are configured in a predetermined pattern. In addition, in FIG. 4, the transmission part 52 is represented in white formally, and the reflection part 53 is represented in gray. Moreover, although the pattern of the transmission part 52 and the reflection part 53 in each division area 51 is the same, it does not necessarily need to be the same and a pattern which changes with division areas may be sufficient. The transmission part 52 and the reflection part 53 may have a grid pattern.

As shown in FIG. 4, the first optical sheet 50 is disposed so that the central portion 51A of each partition region 51 is a region corresponding to each LED element 42, so that the central portion is more central than the outer edge portion 51B. The amount of light incident on 51A increases. For this reason, in each partition area 51, it is preferable that the aperture ratio, which is the area ratio of the transmission part 52, gradually increases from the central part 51A toward the outer edge part 51B. By gradually increasing the aperture ratio in each partition region 51 from the central portion 51A toward the outer edge portion 51B, it is possible to further improve the uniformity of luminance on the light emitting surface while securing a sufficient amount of light. In the present specification, the “aperture ratio” of a partitioned area means that each partitioned area is divided into square cells having an equal area that is divided at an appropriate ratio of about 25 to 100 equal parts. It means the area ratio of the transmission part in the eye. The method of defining the squares having the same area in one partition region is arbitrary. For example, it is desirable to set so that the number of transmission parts 52 present in each square is approximately equal. In addition, the “aperture ratio” defines a plurality of concentric circles centered on the center point of one partition region at equal intervals from the central region to the outer region located outside the central region. You may obtain | require by calculating the area ratio of the permeation | transmission part in each area | region between circumference | surroundings similarly to the above. According to this calculation method, the above “opening ratio” can be defined also for a partitioned area other than a general opening arrangement in which rectangular openings are arranged in a grid pattern. In each partition region 51, the aperture ratio only needs to gradually increase from the central portion 51A toward the outer edge portion 51B. For example, the aperture ratio is constant in a limited partial range near the central portion or the outer edge portion. An area may exist.

In the central portion 51A of each partition region 51, it is preferable that the area ratio is reflection portion> transmission portion. Moreover, in the outer edge part 51B of each partition area | region 51, it is preferable that area ratio is the transmission part> reflection part. Specifically, the area ratio of the transmission part 52 in the outer edge part 51B is preferably 50% or more and 100% or less. The lower limit of the area ratio of the transmission part 52 in the outer edge part 51B is more preferably 60% or more, and preferably 70% or more. In addition, in the outer edge part 51B, the area ratio of the transmission part can theoretically be 100% by forming the reflection part 53 in an island shape. This is a configuration that cannot be achieved with a conventional punched-open light transmitting / reflecting sheet. Thus, when patterning the transmission part 52 and the reflection part 53 of the first optical sheet 50 by a printing method, the flexibility of patterning can be increased.

As shown in FIG. 3, the first optical sheet 50 includes a resin film 54 and a reflective layer 55 laminated on a part of at least one surface of the resin film 54. The reflective layer 55 can be formed by screen printing or the like. In this case, in the first optical sheet 50, a region where the reflective layer 55 exists is the reflective portion 53, and a region where the reflective layer 55 does not exist is the transmissive portion 52.

<Transmission part>
The transmissive portion 52 is a region where the reflective layer 55 is not formed on any of both surfaces of the resin film 54 and is a region where both surfaces of the resin film 54 in FIG. 3 are exposed. As the resin film 54, a conventionally known transparent film is preferably used, and the total light transmittance is preferably 85% or more. The total light transmittance of the transmission part 52 is based on JIS K-7361: 1997 and is attached to a spectrophotometer (for example, product name “V670DS”, manufactured by JASCO Corporation) with an integrating sphere attachment device (for example, integrating sphere unit). The value measured with ISN-723) attached. The total light transmittance is an arithmetic average value of values obtained by measuring three times.

Examples of the resin film 54 include polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). The thickness of the resin film 54 is preferably 12 μm or more and 1 mm (1000 μm) or less. The thickness of the resin film 54 can be measured by the same method as the thickness of the resin film 43.

<Reflecting part>
The reflective portion 53 is a region where the reflective layer 55 in the first optical sheet 50 in FIG. 3 is present. The reflecting portion 53 shown in FIG. 3 is formed on the surface of the resin film 54 on the LED element 42 side, but is not limited thereto, and is formed on the surface opposite to the surface on the LED element 42 side. Alternatively, it may be formed on both surfaces of the resin film 54. The thickness of the reflective layer 55 is preferably 20 μm or more and 200 μm or less. The thickness of the reflective layer 55 can be measured by the same method as the thickness of the insulating protective film 45.

The reflecting portion 53 preferably has a reflectance of at least 80% in the visible light wavelength region with a wavelength of 420 nm or more and 780 nm or less. The reflectivity of the reflection part formed in a narrow range like the reflection part 53 in the first optical sheet 50 is determined using a microspectrophotometer (product name “USPM-RUＲIII”, manufactured by Olympus Corporation). Therefore, it can measure accurately. The value of the reflectance is a value obtained by measuring the relative reflectance with barium sulfate as the standard plate and the standard plate as 100%. The reflectance is an arithmetic average value of values obtained by measuring three times.

The reflective layer 55 can be composed of a cured product of a thermosetting resin composition containing a white pigment such as titanium oxide. The content of the white pigment in the reflective layer 55 is preferably 10% by mass or more and 85% by mass or less in the reflective layer.

Examples of the thermosetting resin in the thermosetting resin composition constituting the reflective layer 55 include conventionally known combinations of urethane resins and isocyanate compounds, combinations of epoxy resins and polyamines and acid anhydrides, silicone resins and cross-linking agents. And a two-component thermosetting resin containing a main agent and a curing agent, and a three-component thermosetting resin containing a curing accelerator such as amine, imidazole, and phosphorus. It is done. Specifically, examples of the thermosetting resin include silicone-based thermosetting resins described in JP-A No. 2014-129549. The reflective layer 55 can be formed by pattern-printing the thermosetting resin composition on the surface of the resin film 54 using, for example, a printing method such as screen printing. In addition, said thickness and reflectance are the total thickness of the thickness of both surfaces, when a reflective layer is formed on both surfaces of a resin film, and are the reflectance when a reflective layer is formed on both surfaces.

As described above, the first optical sheet 50 shown in FIG. 3 includes the resin film 54 and the reflective layer 55 laminated on a part of at least one surface of the resin film 54. As shown in FIG. 5, the first optical sheet has a plurality of openings 135 penetrating in the thickness direction of the light reflective sheet 134 in a light reflective sheet 134 such as foamed polyethylene terephthalate (PET). The first optical sheet 130 may be used. Similar to the first optical sheet 50, the first optical sheet 130 includes a partition region 131, a transmission part 132, and a reflection part 133. The partition area 131, the transmission part 132, and the reflection part 133 in the first optical sheet 130 are the same as the partition area 51, the transmission part 52, and the reflection part 53 in the first optical sheet 50. Shall be omitted. Note that also in each partition region 131 of the first optical sheet 130, the aperture ratio, which is the area ratio of the transmission part 132, gradually increases from the central portion 131A of the partition region 131 toward the outer edge portion 131B of the partition region 131. It is preferable. In the case of the first optical sheet 130, the opening 135 functions as a transmission part 132 that transmits light, and a part other than the opening 135 in the first optical sheet 130 functions as a reflection part 133 that reflects light. . The openings 135 have an arbitrary shape (for example, a circular shape or a rectangular shape), and are dispersedly arranged so as not to be connected to each other along a predetermined pattern. The opening 135 can be formed by press punching, punching with an engraving blade, drilling, laser processing, or the like. Press punching is an effective manufacturing method for mass production because of its excellent running cost and productivity.

<< First spacer >>
The first spacer 60 is for separating the first optical sheet 50 from the LED mounting substrate 40. The first spacer 60 has a function of holding the distance d1 from the surface 41A of the wiring board 41 to the first optical sheet 50 at 0.6 mm or more and 6 mm or less.

The height h1 of the first spacer 60 shown in FIG. 3 is preferably 0.5 mm or more and 5 mm or less. When the height of the first spacer is less than 0.5 mm, the distance between the LED element and the first optical sheet is too short, so that each of the first optical sheets in the plan view of the first optical sheet There is a possibility that the central part of the partition area is brighter than the outer edge part, and if it exceeds 5 mm, the LED surface light source device may not be thinned. In the present specification, “the height of the first spacer” is opposite to the bottom surface of the first spacer from the bottom surface of the first spacer in the direction perpendicular to the bottom surface of the first spacer on the wiring board side. It means the distance to the upper surface which is the side surface. The height h1 of the first spacer 60 is an arithmetic average value of values obtained by randomly measuring the height of the first spacer 60 at ten locations.

It is preferable that the first spacer 60 and the wiring board 41 are fixed. The method for fixing the first spacer 60 and the wiring board 41 is not particularly limited, and examples thereof include fixing by adhesion or mechanical fixing means. In the present specification, “adhesion” is a concept including “adhesion”. In FIG. 3, the first spacer 60 and the wiring board 41 are fixed via a double-sided tape 111. Specifically, the bottom surface 60 A of the first spacer 60 (the bottom surface of the wall portion 62 described later) and the reflective layer 46 of the wiring substrate 41 are fixed by being bonded via a double-sided tape 111. By fixing the first spacer 60 and the wiring board 41, the positional deviation of the first spacer 60 with respect to the LED element 42 can be suppressed. Note that the first spacer 60 and the wiring board 41 may be fixed using an adhesive or an adhesive instead of the double-sided tape 111. In FIG. 3, the first spacer 60 is fixed to the reflective layer 46, but by forming a through hole in the reflective layer of the wiring board or by not providing the reflective layer on the wiring board, The first spacer may be fixed to the insulating protective film, and a through hole is formed in the reflective layer and the insulating protective layer of the wiring board, or the reflective layer and the insulating protective layer are not provided on the wiring board. Thus, the first spacer may be fixed to the metal wiring part.

It is preferable that the first spacer 60 and the first optical sheet 50 are fixed. A method for fixing the first spacer 60 and the first optical sheet 50 is not particularly limited, and examples thereof include fixing by adhesion or mechanical fixing means. In FIG. 3, the first spacer 60 and the first optical sheet 50 are fixed by being bonded via a double-sided tape 112. Specifically, the upper surface 60B of the first spacer 60 (the upper surface of the wall portion 62 described later) and the first optical sheet 50 are bonded via a double-sided tape 112. By fixing the first spacer 60 and the first optical sheet 50, the positional deviation of the first optical sheet 50 with respect to the first spacer 60 and the LED element 42 can be further suppressed. Note that the first spacer 60 and the first optical sheet 50 may be fixed using an adhesive or a pressure-sensitive adhesive instead of the double-sided tape 112.

As shown in FIG. 6, the first spacer 60 divides the opening 61 from two or more openings 61 penetrating in the height direction of the first spacer 60, and at least one of the openings 61. And a wall portion 62 surrounding the periphery.

<Opening>
The opening 61 is for allowing light from each LED element 42 to pass through. Although the number of openings 61 is not particularly limited, in FIG. 6, corresponding to the number of LED elements 42 (vertical 4 × 6 horizontal = 24), 4 vertical × 6 horizontal = 24 openings. A portion 61 is formed.

Since each opening 61 allows light from each LED element 42 to pass therethrough, each opening 61 has a size that allows the LED element 42 to enter the opening 61 when the first spacer 60 is viewed in plan. It has become. In the present embodiment, one LED element 42 is disposed in one opening 61, but a plurality of LED elements may be disposed in one opening.

The openings 61 shown in FIG. 6 are all the same size, but the openings 61 do not have to be the same size and may be different sizes.

<Wall>
As described above, the wall portion 62 partitions the openings 61 and surrounds at least one opening 61. The wall 62 preferably surrounds two or more openings 61, and more preferably surrounds all the openings 61. The wall 62 shown in FIG. 6 has a lattice shape and surrounds all the openings 61. The “lattice shape” in the present specification means a structure in which a plurality of openings are arranged in a matrix shape by wall portions in a plan view of the first spacer. Examples of the shape of the opening in the plan view of the first spacer include a polygonal shape such as a square shape, an elliptical shape, and a circular shape. Examples of the quadrangular shape include a square shape, a rectangular shape, and a rhombus shape. In the first spacer 60 shown in FIG. 6, square-shaped openings 61 are arranged in a matrix by wall portions 62.

The wall portion 62 has a lattice shape, but the wall portion may not have a lattice shape. For example, the wall portion may have openings arranged in a staggered pattern. Specifically, as in the first spacer 140 shown in FIG. 8, the wall 142 may have a honeycomb shape. Similarly to the first spacer 60, the first spacer 140 shown in FIG. 8 includes two or more openings 141, and the wall 142 partitions the openings 141 and has at least one opening. 141 is surrounded. Since the first spacer 140 is the same as the first spacer 60 except that the wall 142 is formed in a honeycomb shape, the description thereof is omitted here. When the LED mounting substrate 40 in which the LED elements 42 are arranged in a matrix is used, the first spacer 60 in which the wall portions 62 are in a lattice shape is used, and the LED mounting in which the LED elements are arranged in a staggered manner. In the case of using a substrate, the first spacer 140 in which the wall 142 has a honeycomb shape can be used.

Further, like the first spacer 150 shown in FIG. 9, the corner portion 152 A on the opening 151 side of the wall portion 152 may be curved in a plan view of the first spacer 150. Since the corner portion 152A has a curved shape in a plan view of the first spacer 150, the wall portion 152 is not easily broken even when vibration or impact is applied to the wall portion 152. Since the number of reflections in the portion 152A can be reduced, a reduction in luminance can be suppressed. Similarly to the first spacer 60, the first spacer 150 shown in FIG. 9 also includes two or more openings 151, and the wall 152 partitions the openings 151 and at least one opening. 151 is surrounded. Since the first spacer 150 is the same as the first spacer 60 except that the corner portion 152A of the wall portion 152 is curved, description thereof will be omitted here.

The thickness of the wall portion 62 is preferably 0.5 mm or more and 10 mm or less. If the thickness of the wall portion 62 is 0.5 mm or more, the function as a support for the first optical sheet 50 can be reliably achieved, and if it is 10 mm or less, the opening diameter of the opening portion 61 is sufficiently large. Therefore, a decrease in luminance can be suppressed. In the present specification, the “wall thickness” means the thickness of the thinnest portion of the wall. The thickness of the wall part 62 does not need to be all uniform. In addition, the thickness of the frame part 63 and the partition part 64 which comprise the wall part 62 may be the same, but does not need to be the same.

As shown in FIG. 3, the side surface 62 A facing the opening 61 of the wall 62 has a large opening diameter from the bottom surface 60 A to the top surface 60 B in the height direction of the first spacer 60. It is inclined to become. That is, the wall part 62 has a tapered shape in which the thickness of the upper part is thinner than the thickness of the bottom part. By forming the wall portion 62 having such an inclined side surface 62A, the emitted light from the LED element 42 can be reflected by the side surface 62A of the wall portion 62 and guided to the first optical sheet 50. Light can be emitted from the LED surface light source device 20 more efficiently.

When lighting only some of the LED elements, it is desirable to suppress light leakage from the section surrounded by the wall from the viewpoint of local dimming control. However, all the LED elements are turned on. In some cases, it is desirable that light be incident uniformly on the first optical sheet. Here, when all the LED elements are turned on, if the light transmittance of the wall portion of the first spacer is low, the portion where the wall portion of the first spacer exists becomes dark, and the first optical sheet is viewed in plan view. If you do, there is a risk that the wall will become a shadow. On the other hand, even with the same material, the light transmittance tends to change depending on the thickness of the member. Specifically, the light transmittance of the thin member is higher than that of the thick member. By forming the wall portion 62 having the inclined side surface 62 as described above, the thickness of the upper portion of the wall portion 62 becomes thinner than the thickness of the bottom portion of the wall portion 62. Light can be transmitted to an inconspicuous extent. As a result, when only some of the LED elements 42 are lit, light leakage from the section surrounded by the wall portion 62 can be suppressed, and when all the LED elements 42 are lit, the wall It can suppress that the location where the part 62 exists becomes dark. Further, since the outer edge portion 51B near the boundary portion 51C of the partition area 51 of the first optical sheet 50 has the highest aperture ratio, the first spacer is located at a position corresponding to the outer edge portion 51B near the boundary portion 51C. By disposing 60, it is possible to emit a lot of light, and thereby it is possible to further suppress the location where the wall 62 is present from becoming dark. Further, when the first spacer 60 transmits light slightly (when the light transmittance between side surfaces described later exceeds 0%), the first spacer 60 is scattered by light inside the first spacer 60. Since 60 looks bright, it can further suppress that the location where the wall part 62 exists becomes dark. In addition, from the viewpoint of local dimming control, a wall portion is formed so as to surround the light source in the reflection sheet, and by providing a gap between the wall portion and the optical sheet, a portion where the wall portion of the reflection sheet exists becomes dark. Although the technique which suppresses this is known (for example, refer international publication 2017/002307), in this technique, in order to suppress that the location in which the wall part of a reflection sheet exists becomes a wall part, It is necessary to provide a gap between the optical sheet and the optical sheet. On the other hand, in the present embodiment, the wall portion 62 having the inclined side surface 62 as described above can suppress the location where the wall portion 62 is present from becoming dark, so the wall portion 62 and the first portion There is no need to provide a gap between the optical sheets 50. For this reason, since the contact area of the 1st spacer 60 and the 1st optical sheet 50 can be increased, the bending of the 1st optical sheet 50 can be suppressed more.

The first spacer 60 including the wall portion 62 having the inclined side surface 62A can be obtained by, for example, injection molding, cutting, or a three-dimensional printer. The side surface 62A may be curved in the cross section in the height direction of the first spacer 60, but is preferably linear from the viewpoint of ease of manufacture. Further, the wall portion may be inclined so that the opening diameter of the opening portion increases from the upper surface to the bottom surface of the first spacer.

The wall portion 62 preferably has antistatic properties. If dust adheres during manufacture or use of the LED surface light source device, it may cause a failure. However, the wall 62 has antistatic properties, so that dust adheres during manufacture or use of the LED surface light source device. Can be suppressed. Since the antistatic property can be represented by a surface resistance value, when the wall portion 62 has the antistatic property, the surface resistance value of the wall portion 62 is preferably 10 ¹² Ω / □ or less. The surface resistance value can be measured using a resistivity meter (product name “HIRESTA-UP MCP-HT450”, manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: URS) in accordance with JIS K6911: 2006. . The surface resistance value of the wall portion 62 is obtained by measuring ten surface resistance values of the wall portion 62 at random and calculating the arithmetic average value of the measured surface resistance values at ten locations. Examples of a method for imparting antistatic properties to the wall portion 62 include a method of coating a composition containing an antistatic agent by spraying or dipping.

The glass transition temperature (Tg) of the wall 62 is preferably higher than 85 ° C. When an LED surface light source device is incorporated in a vehicle such as an automobile, the wall 62 is heated by an engine or the like. Therefore, even if the wall 62 is subjected to an environmental test in which the wall 62 is left at 85 ° C. for 1000 hours. It is required that it does not flow. If the glass transition temperature of the wall portion 62 exceeds 85 ° C., the flow of the wall portion 62 is suppressed even when the wall portion 62 is subjected to an environmental test for 1000 hours in an environment of 85 ° C. it can. Further, since there is a risk that heat higher than the environmental test is applied in the summer, it is more preferable that the glass transition temperature of the wall 62 exceeds 115 ° C. in consideration of the summer. Here, since the LED surface light source device is very thin, the distance between the first optical sheet and the LED mounting substrate is designed very precisely, and the wall portion flows temporarily. Then, since the distance between the first optical sheet and the LED mounting substrate changes, luminance unevenness occurs, and luminance in-plane uniformity decreases. For this reason, the heat-resistant reliability of the wall 62 is very important. The glass transition temperature of the wall portion 62 is measured by scraping 10 mg of the wall portion 62 as a sample and using a differential scanning calorimeter (DSC) at a temperature rising rate of 5 ° C./min. Let the glass transition temperature of the wall part 62 be the arithmetic mean value of the value measured 3 times. When the glass transition temperature of the wall 62 is confirmed to be 2 or more, the lowest glass transition temperature is adopted as the glass transition temperature.

The molding shrinkage rate of the wall 62 is preferably less than 1.0%. If the molding shrinkage rate of the wall portion 62 is less than 1.0%, the dimensional change of the wall portion 62 and the occurrence of warpage during cooling after molding can be suppressed. The measurement of the molding shrinkage rate of the wall portion 62 is performed based on JIS K6911: 1995. When the molding shrinkage rate of the wall portion 62 is measured, the resin constituting the wall portion 62 by heating the wall portion 62. A molded product obtained by melting the resin, pouring the resin into a mold and solidifying the resin is used.

It is preferable that a convex portion is provided on the upper surface of the wall portion on the first optical sheet side. As described above, the first spacer can be produced by injection molding, punching, cutting, or a three-dimensional printer. However, when a convex portion is provided on the first spacer, among these, the convex From the viewpoint of easy formation of the part, injection molding is preferable.

When providing a convex part in a wall part, the hole part is provided in the 1st optical sheet, and the convex part has penetrated into the hole part. By providing such a hole and a convex portion, the alignment of the first optical sheet with respect to the LED element is facilitated, and even when a vibration test is performed, the first optical sheet with respect to the LED element is not aligned. Misalignment can be further suppressed.

When using the 1st optical sheet 130 which has the several opening part 135 which penetrates as a 1st optical sheet, you may utilize one or more opening parts 135 among the opening parts 135 as said hole part. In this case, since the opening 135 is a through hole, the hole is also a through hole. However, when the hole is provided separately from the opening 135, the hole may not be a through hole. The “hole” in the present specification is a concept including not only a through hole but also a hole that does not penetrate, such as a dent. Moreover, even if it is an optical sheet which does not have the opening part which functions as a permeation | transmission part, if it is an optical sheet which has a hole part which enters a convex part, it is applicable.

The convex portion is for aligning the position of the first optical sheet having a plurality of openings that function as transmission portions for the LED elements, and for suppressing the positional deviation of the first optical sheet. The convex portion enters the opening that functions as the hole.

The shape of the convex portion is not particularly limited, and examples thereof include a cone shape, a truncated cone shape, a pyramid shape, a truncated pyramid shape, a dome shape, and an irregular shape.

From the viewpoint of not affecting the optical performance of the first optical sheet, the height of the convex portion is preferably set to be equal to or less than the thickness of the first optical sheet (less than the height of the opening). Further, from the viewpoint of suppressing the positional deviation of the first optical sheet, it is more preferable that the lower limit of the height of the convex portion is ¼ or more of the thickness of the first optical sheet.

The diameter and width of the convex portion are not particularly limited, but the first optical sheet has a plurality of openings having different diameters, so that the diameter does not enter an opening smaller than the target opening. It is preferable that

One or more convex portions may be formed as a whole of the first spacer, but a plurality of convex portions are preferably formed from the viewpoint of further suppressing displacement of the first optical sheet. Furthermore, from the viewpoint of further suppressing the positional deviation of the first optical sheet, it is preferable that convex portions are formed at least at four places so that a quadrangle is drawn by the convex portions in plan view of the first spacer. .

The 1st spacer which has a convex part can be produced by injection molding. In addition, it is possible to prepare a convex part separately and fix the convex part to the wall part by an adhesive or the like or mechanical fixing, but when the convex part is fixed to the wall part by an adhesive or the like, Since the portion may be peeled off from the wall portion, it is preferable that the convex portion and the wall portion are integrally formed by injection molding.

The wall part 62 shown in FIG. 6 includes a frame part 63 and a partition part 64 that is positioned inside the frame part 63 and partitions the openings 61. The wall portion 62 is not particularly limited as long as it has a partition portion 64 and surrounds the periphery of at least one opening portion 61. For example, a wall like a first spacer 160 shown in FIG. The part 162 does not include a frame part, is configured only from the partition part 163, and may have a cross beam shape. Similarly to the first spacer 60, the first spacer 160 shown in FIG. 10 also includes two or more openings 161, and the wall 162 partitions the openings 161 and at least one opening. 161 is surrounded. However, in FIG. 10, the wall 162 does not surround the periphery of the opening 161 existing on the outermost periphery. Since the first spacer 160 is the same as the first spacer 60 except that the wall portion 162 is composed only of the partition portion 163, the description thereof will be omitted here.

The wall 62 can be obtained by injection molding, cutting, or a three-dimensional printer. In the wall part 62, the frame part 63 and the partition part 64 are integrally provided, but the frame part 63 and the partition part 64 may not be provided integrally. That is, like the first spacer 170 shown in FIG. 11A, the frame portion 172 and the partition portion 173 are separately manufactured, and the partition portion 173 is arranged inside the frame portion 172 to obtain the wall portion 171. May be. Alternatively, the wall portion 181 may be obtained by joining two or more wall portions 181A like the first spacer 180 shown in FIG.

(Frame part)
The frame portion 63 has a quadrangular shape in plan view, but the shape of the frame portion can be appropriately changed according to the shape of the LED mounting substrate and the like. The frame portion 63 is approximately the same size as the wiring substrate 41.

The frame part 63 is preferably made of the same thermoplastic resin as the partition part 64. Further, the frame part 63 may include a light shielding material, a light shielding layer, and an ultraviolet absorber similar to the partition part 64. The thermoplastic resin, the light shielding material, the light shielding layer, and the ultraviolet absorber in the frame 63 are the same as the thermoplastic resin, the light shielding material, the light shielding layer, and the ultraviolet absorber described in the section of the partitioning portion 64. Shall be omitted.

(Partition)
The partition portion 64 partitions the openings 61 and has two side surfaces 64 A that face the openings 61. The partition portion 64 has a light transmittance from one side surface 64A to the other side surface 64A of the partition portion 64 (hereinafter, this light transmittance is referred to as “light transmittance between side surfaces”) of 30% or less. Yes. It is preferable that the lower limit of the light transmittance between the side surfaces of the partition portion 64 is 2% or more. If the light transmittance between the side surfaces of the partition portion is 2% or more, the partition portion 64 can be prevented from being shaded when the first optical sheet 50 is viewed in plan. The upper limit of the light transmittance between the side surfaces of the partition portion 64 is preferably 20% or less.

The inter-side light transmittance can be measured as follows. First, as shown in FIG. 12A, a part of the partitioning portion 64 of the first spacer 60 is cut out so as to include both side surfaces 64A of the partitioning portion 64 to obtain a sample 190 having a predetermined size. In the sample 190, the surface of the sample 190 that was the side surface 64 A of the partition portion 64 is defined as the first side surface 190 A of the sample 190, and the side surface formed by cutting the partition portion 64 is the second side surface 190 B. Will be described. Since the sample 190 is obtained by cutting the partition portion 64 so as to include both side surfaces 64A of the partition portion 64, the sample 190 has two first side surfaces 190A. Further, since the side surface 64A of the partition portion 64 is inclined, the first side surface 190A of the sample 190 is also inclined.

On the other hand, an ultraviolet-visible near-infrared spectrophotometer (product name “V-7200”, manufactured by JASCO Corporation) with an integrating sphere, a light transmission diffuser plate, a first light duct, and a second light Prepare a duct. Instead of the spectrophotometer, a combination of an equivalent light source and a measurement meter may be used. For example, a diffused light source may be used in place of the light source for irradiating parallel light and the light transmission diffusion plate. An illuminometer may be used instead of the integrating sphere.

When the spectrophotometer is used, the light transmission diffuser plate is used to convert the parallel light emitted from the light source into diffused light. As the light transmission diffusion plate, a milky white acrylic plate can be used. The first light duct is for guiding the diffused light to the sample, and the second light duct is for guiding the light transmitted through the sample to the integrating sphere. The first optical duct and the second optical duct have a cylindrical shape, and a metal such as aluminum or silver or a multilayer reflective film so that the inner surfaces of the first optical duct and the second optical duct are specularly reflected. It consists of When the illuminance meter is used, the first optical duct is for guiding light from the light source to the sample, and the second optical duct is configured to transmit the light transmitted through the sample to the illuminance meter. It is for leading up to.

The opening of the first light duct and the second light duct is smaller than the side surface of the sample and the opening of the integrating sphere. In addition, each opening edge part of a 1st optical duct and a 2nd optical duct becomes a shape along the 1st side surface of a sample, in order to make the whole opening edge part contact the 1st side surface of a sample. ing. For example, when the first side surface of the sample is inclined, the opening edge of the optical duct is also inclined along the first side surface of the sample.

When measuring the light transmittance between the side surfaces of the sample 190, first, as shown in FIG. 12B, between the light source 201 capable of irradiating the parallel light of the spectrophotometer and the integrating sphere 202, the light source 201 From the side, the light transmission diffusion plate 203, the first light duct 204, and the second light duct 205 are arranged in this order. Further, in order to suppress leakage of light emitted from the first optical duct 204, the second optical duct 204 is slightly inserted into the opening 202A of the integrating sphere 202. In this state, the light source 201 is turned on, and the amount of light (τ ₁ ) incident on the integrating sphere 202 via the first optical duct 204 and the second optical duct 205 is measured. This amount of light is equal to the amount of light incident on the sample 190 in consideration of light absorption by the second optical duct 205 in FIG. At this time, when a gap is generated between the first optical duct 204 and the second optical duct 205, a third gap for closing the gap between the first optical duct 204 and the second optical duct 205 is provided. An optical duct 206 may be arranged. Further, a reflector 207 for returning leakage light may be provided in the gap between the second optical duct 205 and the opening 202A of the integrating sphere 202.

Thereafter, between the light source 201 and the integrating sphere 202, the light transmission diffusion plate 203, the first optical duct 204, the sample 190, and the second optical duct 205 are arranged in this order from the light source 201 side. At this time, in order to suppress light leakage from between the sample 190 and the first light duct 204 and light leakage from the sample 190 and the second light duct 205, the first light duct 204 is connected to the opening edge portion. 204A is arranged so that the entire 204A contacts the first side 190A of the sample 190 on the light source 201 side, and the second optical duct 205 is disposed on the integrating sphere 202 side of the sample 190. It arrange | positions so that it may contact 190A. Further, the second optical duct 205 is slightly inserted into the opening 202A of the integrating sphere 202 in order to suppress leakage of light emitted from the second optical duct 205. In this state, the light source 201 is turned on, and light from the light source 201 is incident from the first side surface 190 A on the light source 201 side of the sample 190 through the first optical duct 204. The amount of light (τ ₂ ) that passes through the sample 190, exits from the first side surface 190 A of the sample 190 on the integrating sphere 202 side, and enters the integrating sphere 202 through the second optical duct 205 is measured. Since this light amount is the amount of light transmitted through the sample 190, this light amount is referred to as “transmitted light amount”.

Then, the light transmittance between the side surfaces is obtained by the ratio (τ ₂ / τ ₁ × 100) of the transmitted light amount (τ ₂ ) transmitted through the sample 190 with respect to the incident light amount (τ ₁ ) incident on the sample 190. The light transmittance between the side surfaces is an arithmetic average value of values obtained by measuring three times. As shown in FIG. 12C, the upper and lower surfaces of the sample 190 are not covered by the optical duct. This is because the luminous flux emitted from the upper and lower surfaces of the sample 190 is not measured as the amount of transmitted light.

The arithmetic average roughness Ra of at least one side surface 64A of the partition portion 64 is preferably 10 μm or less. If Ra of side surface 64A is 10 micrometers or less, since the frequency | count of reflection will not increase too much, it can suppress that the frequency | count that the partition part 64 absorbs light increases, and can suppress the fall of the in-plane uniformity of a brightness | luminance. Ra can be measured using a surface roughness measuring device (product name “SE-3400”, manufactured by Kosaka Laboratory) in accordance with JIS B0601: 1999. Ra is measured at 10 locations at random, and is the arithmetic average value of the measured 10 locations of Ra.

The partition part 64 contains a thermoplastic resin. Since the partition part 64 contains the thermoplastic resin, weight reduction and cost reduction can be achieved compared with the case where the first spacer is made of only metal. The partition part 64 shown by FIG. 6 is comprised only from the partition part main body 65 containing a thermoplastic resin and the light-shielding material which exists in a thermoplastic resin.

The partition body may not include a light shielding material as long as the entire partition has light shielding properties. Further, since not only visible light but also ultraviolet rays are radiated from the LED element 42, there is a possibility that the members in the LED surface light source device 20 are deteriorated by the ultraviolet rays. For this reason, in order to suppress ultraviolet-ray deterioration, it is preferable that the partition part 64 further contains the ultraviolet absorber other than a thermoplastic resin and a light-shielding material.

The thermoplastic resin constituting the partition main body 65 is not particularly limited, but polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), acrylonitrile / ethylene. -Propylene-diene styrene resin (AES resin), polymethyl methacrylate resin (PMMA resin), polyacetal resin, polyvinyl chloride resin, polyethylene resin, polypropylene resin, polyethylene terephthalate resin, or a mixture of two or more of these resins Etc. Among these, polycarbonate resin, ABS resin, ASA resin, AES resin, PMMA resin, polyacetal resin, or a mixture of two or more of these resins is preferable from the viewpoint of heat resistance, moldability, and the like.

The Young's modulus at 25 ° C. of the thermoplastic resin is preferably 0.5 GPa or more and 5 GPa or less. If the Young's modulus of the thermoplastic resin is less than 0.5 GPa, there is a risk that the strength for fixing the wiring board and the first optical sheet may not be secured at the wall, and if it exceeds 5 GPa, the LED surface When the light source device is installed on a curved surface or the like, the partition portion may not be bent. The lower limit of the Young's modulus at 25 ° C. of the thermoplastic resin is more preferably 1 GPa or more, and the upper limit is more preferably 4 GPa or less.

As the light shielding material, a material that reduces the light transmittance between the side surfaces is used, and a material that returns light to the incident direction by scattering, a material that absorbs light, or the like is used. Examples of the light shielding material include white pigments made of titanium oxide, alumina, talc, aluminum hydroxide, mica, calcium carbonate, zinc sulfide, zinc oxide, barium sulfate, potassium titanate, and the like, or a mixture thereof. It is preferable that the light shielding material in the partition body is included in a ratio of 10 parts by mass to 250 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

The ultraviolet absorber is not particularly limited, and examples thereof include a triazine ultraviolet absorber and a benzotriazole ultraviolet absorber. Among these, a triazine-based ultraviolet absorber is preferred from the viewpoint that it absorbs ultraviolet light efficiently without absorbing light in the visible light region as much as possible and is less likely to cause yellowing even after long-term use. As a commercial item of a triazine type ultraviolet absorber, for example, TINUVIN® 1577® ED manufactured by BASF may be mentioned. Moreover, you may add a hindered amine light stabilizer etc. as needed.

The partition part 64 is preferably provided integrally with the frame part 63, as shown in FIG. By forming the partition portion 64 integrally with the frame portion 63, it is possible to obtain a first spacer without a joint. Therefore, the assembly process of the LED surface light source device is performed rather than configuring the first spacer from a plurality of members. And the risk of displacement of the first optical sheet in the vibration test can be reduced. In addition, since the first spacer has no seam, there is no light entering the seam, and optical loss can be reduced. In this specification, “provided integrally” means not only when there is no boundary between the frame portion and the partition portion, that is, when the frame portion and the partition portion are integrally formed, but also the partition portion. It is a concept including the case where is joined to the frame. In the first spacer 60, the frame part 63 and the partition part 64 are integrally formed. In addition, although the partition part 64 is preferably provided integrally with the frame part 63 from a viewpoint of increasing the strength of the wall part 62, the partition part may not be provided integrally with the frame part.

It is preferable that the partition part 64 is arrange | positioned in the position corresponding to the boundary part 51C between the division areas 51, as FIG. 7 shows. In the present specification, the “boundary portion between partitioned regions” means a portion including a region that is assumed to be a boundary between partitioned regions based on patterns of the transmissive portion and the reflective portion. FIG. 7 is a plan view of the first spacer 60 and the first optical sheet 50 from the LED element 42 side.

Although the partition part 64 shown by FIG. 6 is comprised only from the partition part main body 65, you may be comprised from the partition part main body containing a thermoplastic resin, and the light shielding layer. In this case, the partition part main body does not need to contain the light shielding material.

The partition part 210 shown in FIG. 13A includes a partition part body 211 and a light shielding layer 212 provided on both

side surfaces

211A and 211B of the partition part body 211. The “side surface of the partition unit main body” in the present specification means a surface located on the opening side among the surfaces of the partition unit main body. Therefore, the light shielding layer 212 is positioned closer to the opening 213 than the partition body 211. In addition, since the partition part main body 211 is the same as that of the partition part main body 65, and the opening part 213 is the same as the opening part 61, it abbreviate | omits description here.

The light shielding layer 212 is a layer having a function of shielding incident light. The light shielding layer 212 has a single layer structure, but may have a multilayer structure of two or more layers.

The thickness of the light shielding layer 212 is preferably 0.1 μm or more. If the thickness of the light shielding layer 212 is 0.1 μm or more, the light can be effectively shielded. The thickness of the light shielding layer 212 can be measured by the same method as the thickness of the insulating protective film 45. The upper limit of the thickness of the light shielding layer 212 is preferably 50 μm or less from the viewpoint of suppressing loss due to light absorption in the light shielding layer 212 and maintaining sufficient brightness as a light source.

The light blocking layer 212 is not particularly limited as long as it has a function of blocking incident light, but includes a light reflecting layer or a light absorbing layer. By using a light reflecting layer or a light absorbing layer as the light shielding layer, high light shielding properties can be obtained. The light absorption layer absorbs light, whereas the metal layer can reflect light, and therefore, the light reflection layer is preferable from the viewpoint of effective use of light.

Examples of the light reflecting layer include a resin layer or a metal layer containing a pigment having light reflectivity. The metal layer may be a layer containing one or more metals selected from the group consisting of aluminum, silver, nickel, and chromium. By using a layer containing such a metal as the metal layer, a high reflectance can be obtained, so that incident light can be reflected more, and thus the light utilization efficiency can be improved. Among these, aluminum is preferable because it has high reflectance and does not change the color of reflected light. The “metal layer” in the present specification is a concept including a metal foil.

The light absorption layer includes a resin and a color material dispersed in the resin. Examples of the resin include a polymer of a polymerizable compound and a thermoplastic resin. Although it does not specifically limit as a color material, From the point of light absorption performance, black color materials, such as carbon black and titanium black, are preferable, for example.

A method for forming the light shielding layer 212 is not particularly limited. For example, a vapor deposition method such as a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method or a chemical vapor deposition (CVD) method, a plating method, Alternatively, a spray coating method, a dipping method, or the like can be used. Moreover, you may combine these methods. Furthermore, a light-shielding film (for example, metal foil) may be used as the light-shielding layer 212.

Moreover, the partition part 220 shown by FIG. 13 (B) is also comprised from the partition part main body 221 and the light shielding layer 222 provided in the 1st side surface 221A and the 2nd side surface 221B of the partition part main body 221. FIG. However, the partition part main body 221 is formed by bonding the first part 221C including the first side 221A and the second part 221D including the second side 221B. Such a partition 220 has a first portion 221C in which the light shielding layer 222 is formed on one side, a second portion 221D in which the light shielding layer 222 is formed on one side, and the light shielding layer 222 on the opening 223 side. It can be obtained by pasting together.

13A, the light shielding layer 212 is provided on the first side surface 211A and the second side surface 211B of the partition portion main body 211, and in FIG. 13B, the light shielding layer 222 is composed of the partition portion main body 221. The first side 221A and the second side 221B are provided, but the light shielding layer only needs to be provided on at least one side of the partition main body. For example, like the

partition portions

230 and 240 shown in FIGS. 14A and 14B, the light shielding layers 232 and 242 are the first side 231 A of the partition portion main body 231 and the first side of the partition portion main body 241. It may be provided only on the side surface 241A.

Further, as shown in FIG. 15A, the partition portion 250 is opposite to the first portion 251C including the first side surface 251A of the partition portion main body 251 and the first side surface 251A of the partition portion main body 251. A partition body 251 including a second side 251B on the side and having a second part 251D spaced from the first part 251C, and sandwiched between the first part 251C and the second part 251D The light shielding layer 252 may be provided. The partition body 251 is located closer to the opening 253 than the light shielding layer 252. Further, the partition 260 shown in FIG. 15B also includes a first portion 261C including the first side 261A of the partition main body 261, and a first portion 261A on the opposite side of the first side 261A of the partition main body 261. A partition portion body 261 including two side surfaces 261B and having a second portion 261D spaced from the first portion 261C, and a light shielding layer sandwiched between the first portion 261C and the second portion 261D 262, the light shielding layer 262 includes a light shielding layer 262A located on the first portion 261C side and a light shielding layer 262B located on the second portion 261D side. The light shielding layer 262A and the light shielding layer The layer 262B is formed by bonding. In such a partition 260, the

light shielding layers

262A and 262B face each other between the first portion 261C in which the light shielding layer 262A is formed on one side and the second portion 261D in which the light shielding layer 262B is formed on one side. Can be obtained by pasting together.

Since the light shielding layers 222, 232, 242, 252, and 262 are also the same as the light shielding layer 212, description thereof is omitted here. Since the

partition body

221, 231, 241, 251, and 261 are the same as the partition body 65, and the

openings

223 and 253 are the same as the opening 61, description thereof is omitted here. .

<< second optical sheet >>
The second optical sheet 70 is a sheet having an optical function. The second optical sheet is not particularly limited as long as it is a sheet having an optical function, and examples thereof include a light diffusion sheet, a lens sheet, and a reflective polarization separation sheet. The second optical sheet 70 shown in FIGS. 1 and 2 is a light diffusion sheet. By disposing the second optical sheet 70 which is a light diffusion sheet, the light transmitted through the first optical sheet 50 can be further diffused by the second optical sheet 70, and the in-plane uniformity of luminance is further increased. Can be improved. When the second optical sheet is a lens sheet, the lens sheet 90 may not be provided, and when the second optical sheet is a reflection type polarization separation sheet, the reflection type polarization separation sheet. 100 may not be provided. In addition, when a lens sheet or a reflection type polarization separation sheet is used as the second optical sheet, the same one as the lens sheet 90 or the reflection type polarization separation sheet 100 can be used.

The second optical sheet 70 is disposed on the light emission side of the first optical sheet 50. The second optical sheet 70 is separated from the first optical sheet 50 by the second spacer 80. The second optical sheet 70 is disposed substantially parallel to the first optical sheet 50.

The distance d2 from the first optical sheet 50 to the second optical sheet 70 shown in FIG. 3 is preferably 5 mm or less. If the distance d2 exceeds 5 mm, the LED surface light source device may not be thinned. The “distance from the first optical sheet to the second optical sheet” in the present specification refers to the first optical sheet side of the second optical sheet from the second optical sheet side surface of the first optical sheet. It means the distance to the surface. The distance from the first optical sheet 50 to the second optical sheet 70 is an arithmetic average value of values obtained by measuring this distance at 10 random locations. The distance d2 may be 0.5 mm or more. In FIG. 3, the second optical sheet 70 is separated from the first optical sheet 50, but the second optical sheet 70 may be in contact with the first optical sheet 50. In this case, the distance d2 is 0 mm.

From the viewpoint of reducing the thickness of the LED surface light source device 20, the distance (OD) from the surface 41A of the wiring board 41 to the second optical sheet 70 is preferably 1 mm or more and 10 mm or less. The “distance from the surface of the wiring board to the second optical sheet” in this specification means the distance from the surface of the wiring board to the surface of the second optical sheet on the wiring board side. The distance from the surface 41 A of the wiring board 41 to the second optical sheet 70 is an arithmetic average value of values obtained by measuring this distance at 10 random locations. The upper limit of the distance from the surface 41A of the wiring board 41 to the second optical sheet 70 is preferably 5 mm or less.

The thickness of the second optical sheet 70 is preferably larger than the thickness of the first optical sheet 50. Since the thickness of the second optical sheet 70 is larger than the thickness of the first optical sheet 50, the second optical sheet 70 is less likely to bend than the first optical sheet 50. For this reason, the second optical sheet 70 can hold the distance between the first optical sheet 50 and the second optical sheet 70 at a predetermined distance by the frame-shaped second spacer 80.

The thickness of the second optical sheet 70 is preferably 0.3 mm or more and 5 mm or less. This is because if the thickness of the second optical sheet 70 is less than 0.3 mm, the light diffusion effect may not be sufficiently obtained, and if the thickness exceeds 5 mm, the LED surface light source device is thinned. May not be possible. The thickness of the second optical sheet 70 can be measured by the same method as the thickness of the first optical sheet 50.

The second optical sheet 70 is preferably made of a resin. In the present specification, “consisting of resin” means that the resin is a main constituent. The second optical sheet 70 is formed of a translucent resin film made of polycarbonate resin, acrylic resin, or the like, and is formed on one surface side of the resin film. And a lens layer having a lens array or the like.

<< Second spacer >>
The second spacer 80 is for supporting the second optical sheet 70 with respect to the first optical sheet 50. The second spacer 80 holds the distance d2 from the first optical sheet 50 to the second optical sheet 70 to 5 mm or less, and the distance from the surface 41A of the wiring board 41 to the second optical sheet 70. Has a function of holding 1 to 10 mm. When the second optical sheet is in contact with the first optical sheet, the second optical sheet can be supported by the first spacer via the first optical sheet, and therefore the second spacer is provided. It does not have to be, but may be provided. In this case, the second spacer has such a height that the second optical sheet is in contact with the first optical sheet.

The height h2 of the second spacer 80 shown in FIG. 3 is larger than the height h1 of the first spacer 60. The height h2 of the second spacer 80 is preferably 10 mm or less. If the height of the second spacer exceeds 10 mm, the LED surface light source device may not be thinned. In the present specification, the “height of the second spacer” refers to the second spacer from the bottom surface of the second spacer in the direction perpendicular to the bottom surface that is the inner bottom surface of the housing. It shall mean the distance to the top surface. The height h2 of the second spacer 80 is an arithmetic average value of values obtained by measuring the height of the second spacer 80 at 10 random locations. The lower limit of the height h2 of the second spacer 80 may be 1 mm or more.

The second spacer 80 has a frame shape as shown in FIG. The “frame shape” in this specification is not limited to a configuration in which one round is connected without a break, but may have a gap in the middle as long as it is generally connected. The second spacer 80 shown in FIG. 16 is provided with a gap 80A for connection with a terminal or the like. The second spacer 80 has one opening 81 and is disposed so as to surround the outer peripheral surface 50 A of the first optical sheet 50 and the outer peripheral surface 60 C of the first spacer 60. As shown in FIG. 2, the second spacer 80 surrounds not only the outer peripheral surface 50 A of the first optical sheet 50 and the outer peripheral surface 60 C of the first spacer 60 but also the outer peripheral surface 41 C of the wiring substrate 41. Has been placed. That is, the LED mounting substrate 40, the first optical sheet 50, and the first spacer 60 are located inside the second spacer 80. Since the second spacer 80 has a frame shape, the light transmitted through the first optical sheet 50 and directed toward the second spacer 80 is reflected by the second spacer 80, so that the second optical The sheet 70 can be led. In addition, since the second spacer 80 has a frame shape, the contact area with the second optical sheet 70 can be increased as compared with the case where the second spacer is composed of a plurality of columnar bodies. Therefore, when the LED surface light source device 20 is used, the heat of the second optical sheet 70 can be further dissipated through the second spacer 80. In addition, since the second spacer 80 has a frame shape, the second spacer 80 and the second optical sheet 70 are more bonded than in the case where the second spacer is composed of a plurality of columnar bodies. Since the area can be increased, the second optical sheet 70 is less likely to be displaced.

As shown in FIG. 3, the bottom surface 80 B of the second spacer 80 is preferably in contact with the inner bottom surface 30 B of the housing 30. In this specification, “the bottom surface of the second spacer is in contact with the inner bottom surface of the housing” is not limited to the case where the bottom surface of the second spacer is in direct contact with the inner bottom surface of the housing. This is a concept including a case where a layer that can be ignored in terms of heat conduction, such as a double-sided tape, an adhesive, or an adhesive, is interposed between the bottom surface of the spacer and the inner bottom surface of the housing. In FIG. 3, a double-sided tape 113 described later is interposed between the bottom surface 80B of the second spacer 80 and the inner bottom surface 30B of the housing 30.

Also, the outer side surface 80C, which is the outer side surface of the second spacer 80 shown in FIG. 3, is in contact with the inner side surface 30D of the housing 30. In the present specification, the “outer surface of the second spacer” means a surface opposite to the inner surface that defines the opening of the second spacer. In addition, the phrase “the outer surface of the second spacer is in contact with the inner surface of the housing” in this specification is limited to the case where the outer surface of the second spacer is in direct contact with the inner surface of the housing. In addition, the concept includes a case where a layer that can be ignored in terms of heat conduction, such as a double-sided tape, an adhesive, or an adhesive, is interposed between the outer surface of the second spacer and the inner surface of the housing. is there. In FIG. 3, the outer side surface 80 C of the second spacer 80 is in direct contact with the inner side surface 30 D of the housing 30.

It is preferable that the second spacer 80 and the housing 30 are fixed from the viewpoint of further suppressing the displacement of the second optical sheet 70 with respect to the LED element 42. The method for fixing the second spacer 80 and the housing 30 is not particularly limited, and examples include fixing by adhesion or mechanical fixing means. In FIG. 3, the bottom surface 80 B of the second spacer 80 and the inner bottom surface 30 B of the housing 30 are fixed by being bonded via a double-sided tape 113. Here, since the second spacer 80 has a frame shape, the adhesion area with the housing 30 can be increased as compared with the case where the second spacer is composed of a plurality of columnar bodies. The second spacer 80 can be easily fixed. The second spacer 80 and the housing 30 may be bonded via an adhesive or an adhesive instead of the double-sided tape 113.

It is preferable that the second spacer 80 and the second optical sheet 70 are fixed. A method for fixing the second spacer 80 and the second optical sheet 70 is not particularly limited, and examples include fixing by adhesion or mechanical fixing means. In FIG. 3, the upper surface 80 D opposite to the bottom surface 80 B of the second spacer 80 and the second optical sheet 70 are fixed by being bonded via a double-sided tape 114. By fixing the second spacer 80 and the second optical sheet 70, the positional deviation of the second spacer 80 with respect to the LED element 42 can be further suppressed. Note that the second spacer 80 and the second optical sheet 70 may be fixed using an adhesive or an adhesive instead of the double-sided tape 114.

As shown in FIG. 3, the inner side surface 80 E that is the inner side surface of the second spacer 80 has an opening diameter of the opening 81 that increases from the inner bottom surface 30 B of the housing 30 toward the second optical sheet 70. It is preferable to be inclined. That is, the second spacer 80 has a tapered shape in which the thickness of the upper part is thinner than the thickness of the bottom part. By forming the second spacer 80 having such an inclined inner surface 80E, the emitted light from the first optical sheet 50 is reflected by the inner surface 80E of the second spacer 80, and the second optical Since the light can be guided to the sheet 70, light can be emitted from the LED surface light source device 20 more efficiently. The second spacer 80 having such an inclined inner surface 80E can be obtained by, for example, injection molding, punching, cutting, or a three-dimensional printer. The inner side surface 80E may be curved in the cross section in the height direction of the second spacer 80, but is preferably linear from the viewpoint of ease of manufacture.

The material constituting the second spacer 80 is not particularly limited, but is preferably made of resin from the viewpoint of easy molding and protection of the second optical sheet 70 and the like from impact. Among the resins, a white resin is preferable from the viewpoint of increasing the reflectance and further guiding light to the second optical sheet 70.

The resin constituting the second spacer 80 is preferably the same resin as the thermoplastic resin constituting the first spacer 60. However, at present, it is desired to bend the LED surface light source device, and in order to bend the LED surface light source device, when the first spacer and the second spacer are made of a resin having a low Young's modulus, the LED surface Since the rigidity of the light source device is lowered, when the LED surface light source device is bent, the resin 25 constituting the second spacer 80 is bent so that the LED surface light source device can be bent while maintaining a certain degree of rigidity. The Young's modulus at 0 ° C. is preferably smaller than the Young's modulus at 25 ° C. of the thermoplastic resin constituting the first spacer 60. The Young's modulus at 25 ° C. of the thermoplastic resin constituting the first spacer 60 and the Young's modulus at 25 ° C. of the resin constituting the second spacer 80 are respectively determined by a dynamic viscoelasticity measuring device (product name “Rheogel- E4000 "(manufactured by UBM Co., Ltd.) is used, and a tensile test is performed at 25 ° C, and the stress is obtained from the slope of the linear portion of the stress-strain curve with the vertical axis representing stress and the horizontal axis representing strain. In addition, let the said Young's modulus be the arithmetic mean value of the value obtained by measuring 3 times.

<< Lens sheet >>
The lens sheet 90 has a function of changing the traveling direction of incident light and emitting it from the light exit side. As shown in FIG. 17, the lens sheet 90 changes the traveling direction of light having a large incident angle, such as L1, for example, and emits it from the light-emitting side to intensively improve the luminance in the front direction (collection). In addition to the light function, for example, the light having a small incident angle such as L2 is reflected and returned to the first optical sheet 50 side (retroreflection function). As shown in FIG. 17, the lens sheet 90 includes a resin film 91 and a lens layer 92 provided on one surface of the resin film 91. The lens sheet 90 is arranged so that the lens layer 92 is positioned closer to the reflective polarization separation sheet 100 than the resin film 91.

(Resin film)
Examples of the constituent material of the resin film 91 include polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, and polymethyl. Examples of the thermoplastic resin include pentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane.

(Lens layer)
The lens layer 92 includes a plurality of unit lenses 92A arranged side by side on the light output side. The unit lens 92A may have a triangular prism shape, or may have a wave shape or a bowl shape such as a hemisphere. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, and a unit microlens. Examples of the lens sheet having such a unit lens shape include a prism sheet, a lenticular lens sheet, and a microlens sheet.

The unit lens 92A preferably has an apex angle θ of 80 ° or more and 100 ° or less, more preferably about 90 °, from the viewpoint of improving the light utilization efficiency.

<Reflection-type polarized light separation sheet>
The reflection-type polarization separation sheet 100 transmits only a first linearly polarized light component (for example, P-polarized light) out of the light emitted from the lens sheet 90 and is a second straight line orthogonal to the first linearly polarized light component. It has a function of reflecting a polarized light component (for example, S-polarized light) without absorbing it. In the state where the second linearly polarized light component reflected by the reflective polarization separating sheet 100 is reflected again and the polarized light is released (including both the first linearly polarized light component and the second linearly polarized light component), The light again enters the reflective polarization separation sheet 100.

As the reflective polarization separation sheet 100, “VIKUITI (registered trademark)“ Dual ”Brightness“ Enhancement ”Film (DBEF) available from 3M Company can be used. In addition to “VIKUITI (registered trademark) DBEF”, a high-intensity polarizing sheet “WRPS” or a wire grid polarizer available from Shinwha Intertek can be used as the reflective polarization separating sheet 100.

According to the present embodiment, the first spacer 60 includes the partition portion 64 that partitions the openings 61 and includes the wall portion 62 that surrounds the periphery of at least one opening 61. Compared with a simple frame-shaped spacer, the contact area with the first optical sheet 50 can be increased. Thereby, the bending of the 1st optical sheet 50 can be suppressed.

In the case where the first optical sheet is a light transmission / reflection sheet, the light transmission / reflection sheet has a pattern of a transmission part and a reflection part in each partition region. Since the position of the light transmitting / reflecting sheet with respect to the element changes, the in-plane luminance uniformity may be reduced. For this reason, it is necessary to keep the distance from the surface of the wiring board to the light transmission / reflection sheet at a predetermined distance. In the present embodiment, since the first spacer 60 can suppress the bending of the first optical sheet 50 that is a light transmitting and reflecting sheet, the in-plane uniformity of luminance can be improved.

According to the present embodiment, since the first spacer 60 has the partition portion 64 having a light transmittance between the side surfaces of 30% or less, the light emitted from the LED element and directed to the adjacent LED element side is It is blocked by the partition part 64. Thereby, when local dimming control is performed, mixing of light from the LED elements 42 can be suppressed, which is suitable for local dimming control.

According to the present embodiment, since the first spacer 60 includes the wall portion 62, it has higher rigidity than a columnar spacer or a simple frame-shaped spacer. For this reason, when the vibration test is performed on the LED surface light source device 20, the swing width of the first optical sheet 50 is smaller than when a columnar spacer or a simple frame spacer is used. Thereby, when the vibration test is performed, the positional deviation of the first optical sheet 50 with respect to the LED element 42 can be suppressed. Further, since the first spacer 60 has higher rigidity than a columnar spacer or a simple frame-shaped spacer, the first spacer 60 is not easily damaged even when a vibration test is performed.

In the case where the first optical sheet is a light transmission / reflection sheet, the light transmission / reflection sheet has a pattern of a transmission part and a reflection part in each partition region. Since the position of the light transmitting / reflecting sheet with respect to the LED element changes, the in-plane uniformity of luminance may be lowered. On the other hand, in this embodiment, since the position shift of the 1st optical sheet 50 with respect to the LED element 42 can be suppressed, the in-plane uniformity of a brightness | luminance can be improved.

The

first spacers

140, 150, 160, 170, and 180 also have a partition portion that partitions the openings and includes a wall portion that surrounds at least one of the openings, and thus the first spacer 60 The same effect as above can be obtained. In addition, when the spacer having the

partition portions

190, 200, 210, 220, 230, and 240 and including the wall portion surrounding the periphery of at least one opening is used as the first spacer, the first spacer 60 is also used. The same effect as above can be obtained.

The use of the LED image display device 10 and the LED surface light source device 20 of the present embodiment is not particularly limited, but can be used for television media, in-vehicle applications, billboards and other advertising media. Among these, the LED image display device 10 and the LED surface light source device can withstand vibration tests, and can be suitably used for in-vehicle use.

In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions.

<Example 1>
First, an LED mounting substrate was produced. Specifically, a copper layer having a thickness of 35 μm for wiring was laminated on one surface of a polyimide film having a length of 112 mm × width of 301 mm and a thickness of 25 μm. Thereafter, the copper layer for wiring was etched to form a copper wiring part. After forming the copper wiring portion, an insulating protective film having a thickness of 20 μm was formed by screen printing to obtain a flexible wiring board. After obtaining the flexible wiring board, a total of 60 LED elements of 5 vertical x 12 horizontal were mounted on the copper wiring part of the flexible wiring board via a solder layer by a reflow method to obtain an LED mounting board.

Also, a light transmission / reflection sheet was prepared. The light transmissive reflection sheet was produced by forming a plurality of openings penetrating in the thickness direction in a predetermined pattern on a foamed polyethylene terephthalate film having a thickness of 0.5 mm by press punching. As a result, a light transmitting / reflecting sheet having 60 partition regions in total of 5 vertical portions × 12 horizontal portions each including a transmission portion and a reflection portion was obtained. In the light transmission / reflection sheet, the size of each partition region was 22 mm long × 24.4 mm wide, and the aperture ratio gradually increased from the center of each partition region toward the outer edge.

Moreover, the 1st spacer was produced. The first spacer has a lattice shape and is manufactured by injection molding using a polycarbonate resin containing titanium oxide (TiO ₂ ) as a light shielding material. Titanium oxide was used in an amount of 30 parts by mass with respect to 100 parts by mass of the polycarbonate resin. The first spacers are 22 mm long × 24.4 mm wide, the first spacers penetrating in the height direction of 5 × vertical × 12 horizontal matrix openings, and 112 mm long × 294.8 mm wide. A rectangular frame portion having a bottom surface width of 2 mm, a top surface width of 1.9 mm and a height of 2 mm, and an opening are partitioned, and a bottom surface width of 2 mm, a top surface width of 1.9 mm and a height of 2 mm formed integrally with the frame portion. The wall part which has the partition part which consists of this partition part main body was provided. The wall portion surrounds all the openings. The frame part and the partition part main body were composed of a polycarbonate resin and titanium oxide present in the polycarbonate resin.

Furthermore, a second spacer was produced. The second spacer was produced by injection molding using a polycarbonate resin. The second spacer penetrates in the height direction of a second spacer having a length of 113 mm × width of 306 mm inside the frame portion, and a frame portion of length 117 mm × width 310 mm, width 2 mm, and height 5 mm. And two openings.

Then, the produced LED mounting substrate was placed on an aluminum casing main body having a storage space of 117 mm in length, 310 mm in width, and 7 mm in height so that the LED element was on the upper side. Next, the first spacer prepared above is fixed to the surface of the flexible wiring board in the LED mounting substrate via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation), and further on the first spacer. The produced light transmission reflection sheet was fixed via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). The first spacer is arranged so that light from each LED element passes through the opening of the first spacer, and the light transmitting / reflecting sheet has a boundary portion between the partition regions of the first spacer. It was arrange | positioned so that it might become a position of a partition part. Further, the produced second spacer is disposed between the housing main body, the LED mounting substrate, and the first spacer, and the second spacer is attached to the bottom surface of the housing main body with a double-sided tape (product name “No. 5000NS”). ”, Manufactured by Nitto Denko Corporation). Furthermore, a light diffusion sheet having a length of 117 mm × width of 310 mm and a thickness of 1.5 mm was disposed on the second spacer. Finally, a frame-shaped lid having an opening with a size of 110 mm in length and 303 mm in width was fitted into the housing body to obtain an LED surface light source device. The distance from the surface of the flexible wiring board to the light transmission / reflection sheet is 2 mm, the distance from the surface of the flexible wiring board to the light diffusion sheet is 4.8 mm, and the light transmission / reflection sheet, the light diffusion sheet, and The distance between was 2.3 mm.

<Example 2>
In Example 2, instead of the first spacer composed of the polycarbonate resin containing titanium oxide, the LED surface was used in the same manner as in Example 1 except that the first spacer produced as follows was used. A light source device was obtained. In the production of the first spacer, first, an acrylic resin not containing titanium oxide is injection-molded, and the vertical spacer is 22 mm long by 24.4 mm wide and penetrates in the height direction of the first spacer by 5 vertical by 12 horizontal. The openings are arranged in a matrix, a rectangular frame having a length of 112 mm × width of 294.8 mm, a bottom surface width of 2 mm, a top surface width of 1.9 mm and a height of 2 mm, and the openings are partitioned to be integrated with the frame portion. A partition part main body having a bottom surface width of 2 mm, a top surface width of 1.9 mm, and a height of 2 mm was formed. And the light shielding layer with a film thickness of 15 micrometers was formed by spray-coating with the plating-like spray (silver) by Asahi Pen Co., Ltd. on both sides of the opening part side of a partition part main body, and making it dry at room temperature for 1 hour. . Thereby, the wall part which has a frame part and the partition part which consists of a partition part main body and a light shielding layer was formed, and the 1st spacer was obtained. The wall portion surrounds all the openings.

<Comparative Example 1>
In Comparative Example 1, an LED surface light source device was manufactured in the same manner as in Example 1 except that the first spacer was formed using a polycarbonate resin not containing titanium oxide instead of the polycarbonate resin containing titanium oxide. Obtained.

<Comparative example 2>
In Comparative Example 2, an LED surface light source device was obtained in the same manner as in Example 1 except that a plurality of columnar first spacers were used instead of the lattice-shaped first spacer. The first spacer used in Comparative Example 1 was a columnar shape made of polycarbonate resin and having a diameter of 5 mm and a height of 2 mm, and one spacer was disposed between each LED element. The columnar first spacers were fixed to the flexible wiring substrate and the light reflecting / transmitting sheet through a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation).

<Comparative Example 3>
In Comparative Example 3, in the same manner as in Example 1 except that a frame-shaped first spacer composed of one opening portion having no partitioning portion was used instead of the lattice-shaped first spacer, An LED surface light source device was obtained. The first spacer used in Comparative Example 2 is composed of a polycarbonate resin having a length of 112 mm × width of 294.8 mm, a width of 2 mm, a height of 2 mm, and a length of 108 mm × width of 290.8 mm inside the frame. One opening. The first spacer in a frame shape was fixed to the flexible wiring substrate and the light reflecting / transmitting sheet through a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation).

<Bending evaluation>
In the LED surface light source devices according to Examples and Comparative Examples, it was visually evaluated whether or not the light transmission / reflection sheet was bent. In addition, a bending shall be confirmed with the light transmission reflection sheet before the vibration test mentioned later.
○: Deflection was not confirmed in the light transmission reflection sheet.
X: Deflection was confirmed in the light transmission reflection sheet.

<Measurement of light transmittance between sides>
In the first spacers according to Examples 1 and 2 and Comparative Example 1, the light transmittance between the side surfaces of the partition portion was measured. The light transmittance between the side surfaces was measured as follows. First, a part of the partition portion of the first spacer is cut in a direction orthogonal to the direction in which the partition portion extends so as to include both side surfaces of the partition portion, and the bottom surface width is 2 mm, the top surface width is 1.9 mm, the height is 2 mm, and the length A sample with a thickness of 10 mm was obtained. On the other hand, an ultraviolet-visible near-infrared spectrophotometer (product name “V-7200”, manufactured by JASCO Corporation) equipped with an integrating sphere (inner diameter: 60 mm), a light transmission diffusion plate, a first light duct, A measurement system for the transmittance between the side surfaces of the sample was prepared using the second optical duct. As the light transmission diffusion plate, a milky white acrylic plate having a length of 30 mm, a width of 30 mm, and a thickness of 2 mm was used. The first light duct and the second light duct were in the shape of a square cylinder. The first optical duct was 2 mm long, 10 mm wide, and 20 mm long, and the second optical duct was 2 mm long, 10 mm wide, and 20 mm long. The opening size of the first optical duct was 1.8 mm in length and 9.8 mm in width, and the opening size of the second optical duct was 1.8 mm in length and 9.8 mm in width. . Further, the inner surfaces of the first optical duct and the second optical duct are made of aluminum and are specularly reflected. The opening edge of each one of the first light duct and the second light duct was shaped along the side of the sample so that the entire opening edge was in contact with the side of the sample.

After preparing these, the first light duct and the second light duct are arranged from the light source side between the light source of the spectrophotometer and the integrating sphere, and the second optical duct is slightly inserted into the opening of the integrating sphere. In this state, the light source was turned on, and the amount of incident light (τ ₁ ) incident on the integrating sphere via the first and second optical ducts was measured under the following measurement conditions.
(Measurement condition)
・ Wavelength range: 400nm to 800nm
・ Light source: Tungsten halogen lamp ・ Detector: Photomultiplier tube

Thereafter, a light transmission diffusion plate, a first light duct, a sample, and a second light duct were arranged in this order from the light source side between the light source and the integrating sphere. At this time, in order to suppress light leakage from between the sample and the first light duct and light leakage from the sample and the second light duct, the entire opening edge of one of the samples is connected to the first light duct. The second light duct was placed in contact with the other side of the sample, and the second light duct was placed in contact with the other side of the sample. Further, a second optical duct was inserted slightly into the opening of the integrating sphere. In this state, the light source was turned on under the same lighting conditions as when measuring the amount of incident light, and light from the light source was incident from one side surface of the sample through the first optical duct. Then, the amount of transmitted light (τ ₂ ) transmitted through the sample and incident on the integrating sphere via the second optical duct was measured under the same measurement conditions as those for the incident light amount (τ ₁ ).

And the light transmittance between side surfaces was calculated | required by the ratio ((tau) ₂ / (tau) ₁ * 100) of the transmitted light amount ((tau) ₂ ) which permeate | transmitted the sample with respect to the incident light amount ((tau) ₁ ) incident on the sample. The light transmittance between the side surfaces was an arithmetic average value of values obtained by measuring three times.

<Light / dark evaluation>
In the LED surface light source device according to the example and the comparative example, local dimming control is performed, and on the surface of the LED surface light source device (the surface of the second optical sheet), a portion where the LED element is lit and a portion where the LED element is not lit The difference in light and dark was visually evaluated. The evaluation criteria were as follows.
○: Light and dark were clear.
Δ: Light and dark were unclear.
X: Brightness and darkness were remarkably unclear.

<Evaluation of in-plane brightness uniformity>
In the LED surface light source devices according to the example and the comparative example, a vibration test is performed, and before and after the vibration test, the luminance distribution of the light emitting surface (the surface of the light diffusion sheet) of the LED surface light source device is measured. In addition to evaluating the in-plane uniformity, the rate of change of the in-plane uniformity before and after the vibration test was determined to evaluate how much the in-plane uniformity had decreased before and after the vibration test.

The vibration test is performed on the vibration table of the single-axis electrodynamic vibration test apparatus (product name “EM2605S / H10”, manufactured by IMV Corporation), and the outer surface of the LED surface light source device in the short direction is the vibration table side. In a state where the LED surface light source device is erected, the LED surface light source device is fixed and vibrated for one hour in each of the three axial directions (X direction, Y direction, Z direction) orthogonal to each other under the following conditions: Was done. The vibration conditions were a sweep rate of 1 oct / min, a vibration with an amplitude of ± 0.75 mm when the frequency was 10 Hz to 30 Hz, and an acceleration of 3 G when the frequency was 30 Hz to 500 Hz.

The luminance distribution is 1 m away from the light emitting surface of the LED surface light source device (the surface of the light diffusion sheet) in the normal direction of the light emitting surface in a state where the LED element is turned on by supplying a current of 180 mA per LED element. The measurement was performed using a two-dimensional color luminance meter (product name “CA-2000”, manufactured by Konica Minolta, Inc.).

The in-plane uniformity of the luminance is 22 mm × 146.4 mm in the central region in the measurement region, and the maximum luminance (Lv _max ) and the minimum luminance (Lv _min ) in the luminance distribution within the evaluation range are used. by determining the ratio of the minimum luminance _{_{_{(Lv min) (Lv min /}}} Lv max) with respect to the maximum luminance _{(Lv max),} it was quantified.

Also, using the in-plane brightness uniformity before the vibration test and the in-plane brightness uniformity after the vibration test obtained above, the rate of change in the in-plane brightness before and after the vibration test is obtained, and before and after the vibration test. The degree to which the in-plane luminance uniformity was reduced was evaluated. The evaluation criteria were as follows.
A: The rate of change of the in-plane uniformity of luminance before and after the vibration test was within 10%.
X: The rate of change in in-plane uniformity of luminance before and after the vibration test exceeded 10%.
The rate of change in in-plane uniformity of brightness before and after the vibration test is the difference between the in-plane uniformity of brightness before the vibration test and the in-plane uniformity of brightness after the vibration test (in-plane uniformity of brightness before the vibration test). -In-plane uniformity of luminance after vibration test).

<Appearance evaluation>
In the LED surface light source devices according to Examples and Comparative Examples, the appearance of the first spacer after the vibration test was visually observed and evaluated. The evaluation results were based on the following criteria.
○: In the first spacer, damage such as cracking or breaking was not confirmed.
X: In the first spacer, damage such as cracking or breaking was confirmed.

The results are shown in Table 1.

The following describes the results. In Comparative Example 1, although no deflection was confirmed in the light reflecting sheet, the light transmittance between the side surfaces of the partitioning portion of the first spacer exceeded 30%, and thus the results of the brightness evaluation were inferior. This is considered to be because the light from the LED element penetrates the partition and enters the area where the LED element is not lit. In Comparative Example 2, since the first spacer was columnar and did not have a partition portion, the light transmitting / reflecting sheet was confirmed to be bent, and the results of brightness evaluation were also inferior. In Comparative Example 3, the first spacer is a frame having no partition part, and has no partition part. Therefore, the light transmission / reflection sheet is confirmed to be bent, and the result of the brightness evaluation is also inferior. It was. In Comparative Example 2 and Comparative Example 3, the in-plane uniformity of luminance before the vibration test was low. This is presumably because the light transmission / reflection sheet was bent.

On the other hand, in Examples 1 and 2, since the first spacer was composed of the wall portion provided with the partitioning portion, no bending was confirmed in the light transmission / reflection sheet. In Examples 1 and 2, the in-plane uniformity of luminance before the vibration test was high. This is considered because the light transmission reflection sheet was not bent. Furthermore, since the light transmittance between the side surfaces of the partition part in the first spacer is 30% or less, it is possible to suppress the light of the LED element from passing through the partition part and entering the region where the LED element is not lit. As a result, the brightness evaluation was good.

In Comparative Example 2, the in-plane brightness uniformity after the vibration test was clearly lower than the in-plane brightness uniformity before the vibration test. This is probably because the first spacer was a columnar shape, so that the rigidity was low, and the light transmission / reflection sheet was displaced from the LED element by the vibration test. In Comparative Example 3, the in-plane uniformity of luminance before the vibration test was low. This is presumably because the light transmission / reflection sheet was bent. Furthermore, in Comparative Example 3, the in-plane uniformity after the vibration test was clearly reduced as compared with the in-plane uniformity before the vibration test. This is because the first spacer was a frame-like shape having no partition part, so that the rigidity was low, and it was considered that the light transmission / reflection sheet was displaced from the LED element by the vibration test. It is done.

On the other hand, in Example 1, the deterioration of the in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed as compared with Comparative Examples 2 and 3. This is because the first spacer is composed of a wall part having a frame part and a partition part, so that the rigidity is high, and the positional deviation of the light transmission / reflection sheet with respect to the LED element hardly occurs even in the vibration test. It is considered a thing.

DESCRIPTION OF SYMBOLS 10 ... LED image display apparatus 20 ... LED surface light source device 40 ... LED mounting board 41 ... Wiring board 42 ...

LED element

50, 130 ... 1st optical sheet 50A ... Outer

peripheral surface

51, 131 ...

Partition area

51A, 131A ...

Center part

51B, 131B ...

outer edge portions

52, 132 ...

transmission portions

53, 133 ...

reflection portions

60, 140, 150, 160, 170, 180 ... first spacer 60C ... outer peripheral surface 61 ...

openings

62, 142, 152, 162, 171 ... Wall 63 ...

Frame

64, 210, 220, 230, 240, 250, 260 ...

Partition

65, 211, 221, 231, 241, 251, 261 ... Partition main body 70 ... Second optical sheet 80 ...

Second spacers

212, 222, 232, 242, 252, 262...

Claims

An LED surface light source device including a wiring board, an LED mounting board including a plurality of LED elements mounted on one surface of the wiring board, and an optical sheet disposed on the LED element side, and the LED A spacer that is disposed between the mounting substrate and the optical sheet, and that separates the optical sheet from the LED mounting substrate,
Two or more openings penetrating in the height direction of the spacer;
A partition that partitions between the openings, and a wall that surrounds at least one of the openings, and
The partition has two side faces facing the opening, and includes a thermoplastic resin;
The spacer whose light transmittance from one said side surface in the said partition part to the said other side surface is 30% or less.
The spacer according to claim 1, wherein the partition portion further includes a light shielding material present in the thermoplastic resin.
The spacer according to claim 1, wherein the partition portion includes a partition portion main body including the thermoplastic resin and a light shielding layer provided on at least one side surface of the partition portion main body.
The partition portion includes a partition portion main body including the thermoplastic resin and a light shielding layer, and the partition portion main body includes a first portion including a first side surface of the partition portion main body, and the partition portion main body. A second portion that includes a second side opposite to the first side and that is spaced apart from the first portion, wherein the light shielding layer includes the first portion and the second portion. The spacer according to claim 1, which is sandwiched between
The spacer according to claim 1, wherein the arithmetic average roughness of at least one side surface of the partition portion is 10 µm or less.
The spacer according to claim 1, wherein the wall portion has a lattice shape or a honeycomb shape.
An LED mounting board comprising a wiring board and a plurality of LED elements mounted on one surface of the wiring board;
A first optical sheet disposed on the LED element side;
A first spacer that is disposed between the LED mounting substrate and the first optical sheet and separates the first optical sheet from the LED mounting substrate;
The LED surface light source device, wherein the first spacer is the spacer according to claim 1.
The side surface of the wall facing the opening of the spacer is inclined so that the opening diameter of the opening increases from the wiring board toward the first optical sheet. LED surface light source device described in 1.
The first optical sheet includes a partition region divided into a plurality of parts in plan view, and each partition region includes a plurality of transmission portions that transmit a part of light from the LED element, and the LED element. A plurality of reflecting portions that reflect a part of the light, and an aperture ratio that is an area ratio of the transmitting portion in each partition region gradually increases from a central portion of the partition region toward an outer edge portion of the partition region. The LED surface light source device according to claim 7, wherein the LED surface light source device includes a region where
The LED surface light source device according to claim 7, wherein the thickness of the first optical sheet is 25 μm or more and 1 mm or less.
A second optical sheet disposed on the light exit side of the first optical sheet;
A frame-shaped second spacer disposed so as to surround the outer peripheral surface of the first optical sheet and the outer peripheral surface of the first spacer, and supporting the second optical sheet;
The LED surface light source device according to claim 7, further comprising:
LED surface light source device according to claim 7,
A display panel disposed closer to the viewer than the LED surface light source device;
An LED image display device comprising: