JP6424990B1 - Spacer, surface light source device and image display device - Google Patents

Abstract

  According to one aspect of the present invention, it is used for the surface light source device 20 provided with the first optical sheet 50 and the LED mounting substrate 40 facing the first optical sheet 50, and with the first optical sheet 50 A first spacer 60 disposed between the LED mounting substrate 40 and separating the first optical sheet 50 from the LED mounting substrate 40, the first portion 63 extending in the first direction DR1, and A wall 62 having a second portion 64 extending in a second direction DR2 different from the first direction DR1 and intersecting the first portion 63, and exists in a region other than the wall 62, and A first spacer 60 is provided, comprising an opening 61 as a light passage area to be passed.

Description

Reference to related applications

  The present application is based on Japanese Patent Application No. 2016-253328 (filing date: December 27, 2016), Japanese patent application No. 2016-253332 (filing date: December 27, 2016) and Japanese Patent Application No. 2017-104442, which are prior Japanese applications. Filing date: May 26, 2017), and the entire disclosure of which is incorporated herein by reference.

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

  2. Description of the Related Art An LED image display apparatus, which has been widely spread in recent years, generally comprises a display screen such as a liquid crystal display panel and an LED surface light source apparatus for illuminating the display screen from the back side. Currently, in LED image display devices, edge light type LED surface light source devices are usually used in many cases, but from the viewpoint of brightness, using direct type LED surface light source devices is being 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 the luminance on the light emitting surface of the LED surface light source device. As such an optical sheet, for example, an opening pattern is formed on a resin reflective sheet such as white that reflects light from the LED element, such that the opening gradually increases from immediately above the LED element toward the periphery of the LED element In some cases, the light transmitting and reflecting sheet may be used (see Japanese Patent Application Laid-Open No. 2010-272245). By using a light transmitting / reflecting sheet having such an opening pattern, light on the LED element can be reflected and diffused to the periphery and emitted from the surrounding openings, thus improving the in-plane uniformity of luminance. It can be done.

  In order to improve the in-plane brightness uniformity by the optical sheet, it is necessary to separate the optical sheet from the LED mounting substrate on which the LED element is mounted. Therefore, a plurality of columnar spacers are usually disposed between the LED mounting substrate and the optical sheet in order to separate the optical sheet from the LED mounting substrate.

  However, if a columnar spacer is used, the optical sheet may be bent between the spacers. In particular, 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 the in-plane uniformity of luminance may be reduced.

  In addition, it is currently considered to use the LED image display device as a vehicle such as a car or an advertisement medium. In a vehicle, vibrations are generated from the vehicle, so the vibrations of the vehicle may be transmitted to the LED image display device mounted on the vehicle. Furthermore, in the case of an advertising medium, for example, when an LED image display is used for a mobile billboard having a signboard such as a station home or the like, a vibration of a train or the like or a vibration when moving is an LED image display device It can also be transmitted.

  However, in the conventional LED surface light source device, at present, no countermeasure against vibration or impact is taken. Therefore, when a vibration test is performed on the LED surface light source device provided with the optical sheet and the columnar spacer, even if the alignment between the LED element and the optical sheet is accurately performed, the vibration is caused to occur relative to the LED element. There is a possibility that so-called misalignment may occur as the position of the sheet shifts. In particular, when the light transmitting / reflecting sheet is used as the optical sheet, if the light transmitting / reflecting sheet is displaced, the position of the opening pattern with respect to the LED element is displaced, and the in-plane uniformity of luminance may be degraded. . In addition, when the vibration test is performed, the columnar spacer may be broken.

  In addition, when a light transmitting / reflecting sheet is used as an optical sheet, light directly on the LED element is reflected and diffused around the LED mounting substrate on which the LED element is mounted, with the light transmitting / reflecting sheet separated. Since the in-plane uniformity of luminance is improved by emitting light from the surrounding opening, the alignment between the LED element and the opening pattern is important, but all measures have been taken for the alignment with respect to the LED element. It is the present condition that there is not.

  The present invention has been made to solve the above problems. That is, it is possible to suppress the deflection of the optical sheet, and to suppress the displacement of the optical sheet relative to the opposing member even when the vibration test is performed, and a spacer that is not easily damaged, and the surface light source device and image display It aims at providing an apparatus. Further, it is possible to provide a surface light source device capable of facilitating the alignment of the first optical sheet with respect to the LED element and suppressing positional deviation of the first optical sheet with respect to the LED element, and an image display device provided with the same. To aim.

  According to one aspect of the present invention, it is used in a surface light source device including an optical sheet and an opposing member facing the optical sheet, and disposed between the optical sheet and the opposing member, the opposing member A spacer for separating the optical sheet, wherein a first portion extending in a first direction and a second portion extending in a second direction different from the first direction intersect the first portion; A spacer is provided comprising a wall comprising two parts and a light passing area present in an area other than said wall and passing light.

  In the spacer, the light passing region is two or more openings penetrating in the height direction of the spacer, and the openings are partitioned by the first portion and the second portion of the wall portion. May be

  In the spacer, a side surface facing the opening of the wall may be inclined such that an opening diameter of the opening becomes larger from the opposing member toward the optical sheet.

  In the above-mentioned spacer, the glass transition temperature of the above-mentioned wall may be over 85 ° C.

  In the spacer, the molding shrinkage of the wall may be less than 1.0%.

  In the spacer, the wall portion may be made of polycarbonate resin.

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

  According to another aspect of the present invention, a first optical sheet, an opposing member facing the first optical sheet, and the opposing member disposed between the first optical sheet and the opposing member And a first spacer for separating the first optical sheet, wherein the first spacer is fixed to the opposing member and the first optical sheet, and the first spacer is A surface light source device, which is the above spacer, is provided.

  In the surface light source device, the facing member is an LED mounting board including a wiring board and a plurality of LED elements mounted on one surface of the wiring board, and the first optical sheet is on the LED element side It may be arranged.

  In the above-described surface light source device, the first optical sheet includes a plurality of divided regions in plan view, and each of the plurality of divided regions includes a plurality of transmitting portions transmitting a portion of light, and a portion of the light Even if the aperture ratio, which is the area ratio of the transmission part in each of the divided areas, is gradually increased from the center of the divided area toward the outer edge of the divided area. Good.

  According to another aspect of the present invention, there is provided an LED mounting board including a wiring board and a plurality of LED elements mounted on one surface of the wiring board, and a plurality of LED mounting boards arranged to face the plurality of LED elements. A first spacer which is disposed between the first optical sheet, the LED mounting board, and the first optical sheet, is fixed to the wiring board, and separates the first optical sheet from the LED mounting board And the first optical sheet has a hole in a surface on the first spacer side, and the first spacer has a first portion extending in a first direction; And a light passing area that is present in a region other than the wall and that allows light to pass through, and a wall including a second portion that extends in a second direction different from the direction of the second direction and that intersects the first portion And at the side of the first optical sheet in the wall portion Provided, and 1 and more convex portions entering into the hole portion may be provided with a.

  In the surface light source device, the light passing area is two or more openings penetrating in the height direction of the first spacer, and the opening is formed by the first portion and the second portion of the wall portion. A space may be divided.

  In the above-described surface light source device, the first optical sheet includes a plurality of divided regions in plan view, and each of the plurality of divided regions includes a plurality of transmitting portions transmitting a portion of light, and a portion of the light Even if the aperture ratio, which is the area ratio of the transmission part in each of the divided areas, is gradually increased from the center of the divided area toward the outer edge of the divided area. Good.

  In the above-described surface light source device, the transmission portion of the first optical sheet is an opening penetrating in the thickness direction of the first optical sheet, and at least one of the openings functions as the hole. May be

  In the surface light source device, the thickness of the first optical sheet may be 25 μm or more and 1 mm or less.

  In the above-described surface light source device, the wiring substrate is a resin film having flexibility, and a metal wiring portion provided on the first optical sheet side with respect to the resin film and electrically connected to the LED element. It may be a flexible wiring board provided with

  In the 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 disposed so as to surround them. And a frame-shaped second spacer for separating the second optical sheet from the first optical sheet.

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

  According to one aspect of the present invention, it is possible to suppress deflection of the optical sheet, and to provide a spacer that can suppress positional deviation of the optical sheet with respect to the opposing member even when a vibration test is performed, and is not easily damaged. Can. Moreover, according to the other aspect of this invention, the surface light source device provided with such a spacer and an image display apparatus can be provided. Further, according to another aspect of the present invention, a surface light source device capable of facilitating the alignment of the first optical sheet with respect to the LED element and suppressing the displacement of the first optical sheet with respect to the LED element, and An image display device provided can be provided.

FIG. 1 is an exploded perspective view of the image display device according to the first embodiment. FIG. 2 is a schematic block diagram of the image display device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of a part of the surface light source device according to the first embodiment. FIG. 4 is a plan view of the first optical sheet shown in FIG. FIG. 5 is a plan view of the first spacer shown in FIG. FIG. 6 is a plan view showing the arrangement of the first optical sheet and the first spacer shown in FIG. FIG. 7 is a plan view of another first spacer according to the first embodiment. FIG. 8 is a plan view of another first spacer according to the first embodiment. FIG. 9 is a plan view of another first spacer according to the first embodiment. FIG. 10A and FIG. 10B are plan views of other first spacers according to the first embodiment. 11A and 11B are plan views of other first spacers according to the first embodiment. 12A and 12B are plan views of other first spacers according to the first embodiment. FIG. 13A and FIG. 13B are cross-sectional views of part of another partition part according to the first embodiment. FIG. 14A and FIG. 14B are cross-sectional views of part of another partition part according to the first embodiment. FIG. 15 is a perspective view of the intersection of the first portion and the second portion of another first spacer according to the first 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. FIG. 18 is an exploded perspective view of the image display device according to the second embodiment. FIG. 19 is a schematic block diagram of an image display device according to the second embodiment. FIG. 20 is an enlarged cross-sectional view of a part of the surface light source device according to the second embodiment. FIG. 21 is a plan view of the first optical sheet shown in FIG. FIG. 22 is a plan view of the first spacer shown in FIG. FIG. 23 is a plan view showing the positional relationship between the first optical sheet and the first spacer shown in FIG.

First Embodiment
Hereinafter, a spacer, a direct-type surface light source device, and an image display device according to a first embodiment of the present invention will be described with reference to the drawings. In the present specification, "LED" means a light emitting diode. Also, terms such as "sheet", "film", "plate" and the like are not distinguished from one another based only on the difference in designation. Thus, for example, "sheet" is used to include members such as a film or a plate. FIG. 1 is an exploded perspective view of the image display apparatus according to the present embodiment, FIG. 2 is a schematic configuration view of the image display apparatus according to the present embodiment, and FIG. 3 is a part of the surface light source apparatus 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 the first spacer shown in FIG. 1, and FIG. 6 is the first optical sheet shown in FIG. It is a top view which shows the arrangement | positioning relationship of and the 1st spacer. FIGS. 7 to 12 are plan views of other first spacers according to the present embodiment, and FIGS. 13 and 14 are cross-sectional views of part of other partitions according to the present embodiment, and FIG. FIG. 16 is a perspective view of the intersection of the first portion and the second portion of the first spacer, 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.

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

<<< Area light source device >>>
The 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, and a second optical sheet 70. The spacer 80 is provided. In addition, the surface light source device 20 further includes a lens sheet 90 and a reflective polarization separation sheet 100 laminated on the second optical sheet 70. The surface light source device 20 may 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, the second spacer 80, The lens sheet 90 or the reflective polarization separation sheet 100 may not be provided. The first spacer 60 is used in a surface light source device including an optical sheet and an opposing member facing the optical sheet. In the surface light source device 20, the optical sheet is the first optical sheet 50, and the opposing member is the LED mounting substrate 40. The facing member may not be the LED mounting substrate as long as the facing member is a member facing the optical sheet.

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

<< case >>
The housing 30 includes a housing space 30A for housing the LED mounting substrate 40 and the like. The housing 30 has an inner bottom surface 30B which is an inner bottom surface, an outer bottom surface 30C which is an outer bottom surface, and an inner side surface 30D which is an inner side rising from the inner bottom surface 30B, as shown in FIG. doing. Moreover, the housing | casing 30 has the opening part 30E for radiate | emitting the light from the LED element 42 from the housing | casing 30, as FIG. 2 shows. Preferably, the opening 30E is provided at a position facing the inner bottom surface 30B. The shape of the opening 30E is not particularly limited, and may be, for example, rectangular or circular.

  The housing 30 shown in FIG. 2 includes a housing main body 31 having a housing space 30A, and a frame-like lid 32 covering the housing space 30A of the housing main body 31 and having an opening 30E. In the housing 30, the inner bottom surface 30B of the housing 30 is the inner bottom surface of the housing main body 31, and the inner side surface 30D of the housing 30 is the inner surface of the housing main body 31.

  The housing 30 (the housing body 31 and the lid 32) is preferably made of metal. In particular, by forming the case body 31 from metal, the case body 31 also functions as a heat dissipation structure, so the heat from the LED element 42 can be dissipated efficiently. The metal is not particularly limited, and examples thereof include aluminum and the like.

<< LED mounting board >>
The LED mounting substrate 40 is disposed to face the first optical sheet 50. The LED mounting substrate 40 includes a wiring substrate 41 and a plurality of LED elements 42 mounted on one surface of the wiring substrate 41 (hereinafter, this surface is referred to as “surface”) 41A. As shown in FIG. 2 and FIG. 3, the LED mounting substrate 40 has a surface 41B on the wiring substrate 41 opposite to the surface 41A on which the LED element 42 is mounted (hereinafter this surface is referred to as “rear surface”). The housing 30 is disposed so as to be located on the inner bottom surface 30 </ b> B side of the housing 30.

<Wiring board>
The wiring substrate 41 is disposed along the inner bottom surface 30B of the housing 30. It is preferable that the back surface 41 B of the wiring substrate 41 be in contact with the inner bottom surface 30 B of the housing 30. When the back surface 41B of the wiring substrate 41 contacts the inner bottom surface 30B of the housing 30, the heat of the wiring substrate 41 and the like can be efficiently dissipated to the housing 30 side. In this specification, "the back surface of the wiring substrate is in contact with the inner bottom surface of the housing" is not limited to the case where the back surface of the wiring substrate is in direct contact with the inner bottom surface of the housing. This concept also includes the case where a substantially negligible layer such as a double-sided tape, an adhesive, or an adhesive is interposed between the inner bottom surface of the housing and the double-sided tape.

  In the wiring board 41, as shown in FIG. 3, the resin film 43, the metal wiring portion 44, the insulating protective film 45, and the reflective layer 46 are in this order toward the first optical sheet 50. It is stacked. However, the wiring substrate 41 may not be provided with the insulating protective film 45 or the reflective layer 46. The metal wiring portion 44 is preferably bonded to the resin film 43 by a dry lamination method via the adhesive layer 47. Furthermore, 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 substrate 41 is a flexible wiring substrate, it is possible to obtain a bendable surface light source device. The wiring board 41 shown in FIG. 2 is a flexible wiring board. "Flexible" means flexible, and "flexible wiring substrate" generally means a flexible and bendable wiring substrate. The term "flexible" as used herein means bending so that at least the radius of curvature is 1 m. The flexible wiring substrate is bent so that the radius of curvature is preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, particularly preferably 5 cm.

(Resin film)
The resin film 43 has flexibility. The resin film 43 is a film bent so that the radius of curvature is preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, 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 is preferably one having high heat resistance and insulation. As such a resin, polyimide (PI) and polyethylene naphthalate (PEN), which are excellent in heat resistance, dimensional stability at heating, mechanical strength, and durability, can be used. Among these, polyethylene naphthalate (PEN), in which heat resistance and dimensional stability are improved by performing heat resistance improvement treatment such as annealing treatment, can also be preferably used. Further, polyethylene terephthalate (PET) whose flame retardancy has been improved by the 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 heat shrinkage start temperature of 100 ° C. or higher, or one whose heat resistance is improved to be 100 ° C. or higher by the above-mentioned annealing treatment or the like is used. Is preferred. The “heat shrinkage start temperature” in this specification means that a sample film made of a thermoplastic resin to be measured is set in a thermomechanical analysis (TMA) device, a load of 1 g is applied, and the heating rate is 2 ° C./min. Heat up to ° C, measure the amount of contraction (%) at that time, output this data, and record the temperature and the amount of contraction. Read the temperature away from the baseline by 0% due to contraction, and use that temperature The heat shrinkage start temperature is used. In addition, let heat contraction start temperature be an arithmetic mean value of the value obtained by measuring 3 times.

  In general, the temperature around the LED element may reach a temperature of about 90 ° C. due to the 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 a high insulating property that can provide the wiring substrate 41 with the required insulating property. Therefore, the volume specific resistivity of the resin film 43 is 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 in accordance with JIS C2151: 2006. The volume resistivity is randomly measured at 10 points, and is taken as the arithmetic mean value of the measured 10 volume resistivity.

  The thickness of the resin film 43 is not particularly limited, but it is about 10 μm or more and 500 μm or less from the viewpoint of not being a bottleneck as a heat radiation path, having heat resistance and insulation, and balance of manufacturing costs. Is preferred. The thickness range is also preferable from the viewpoint of maintaining good productivity in the roll-to-roll manufacturing. The thickness of the resin film 43 is obtained by photographing a cross section of the resin film 43 using a scanning electron microscope (SEM), measuring the thickness at any ten places of the resin film 43 in the image of the cross section, and calculating the average value It shall be determined by calculation. The lower limit of the thickness of the resin film 43 is preferably 15 μm or more, more preferably 50 μm or more, and the upper limit of the thickness of the resin film 43 is preferably 250 μm or less.

(Metal wiring section)
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 portion 44 can be formed by patterning a metal foil or the like.

  The thermal conductivity λ of the metal constituting the metal wiring portion 44 is preferably 200 W / (m · K) or more and 500 W / (m · K) or less. The thermal conductivity λ can be measured, for example, using a thermal conductivity meter (product name “QTM-500”, manufactured by Kyoto Denshi Kogyo Co., Ltd.). The thermal conductivity λ is an arithmetic mean value of the values 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).

3.00 * 10 < ^-8 > (ohm) m or less is preferable, and, as for the electrical resistivity R of the metal which comprises the metal wiring part 44, 2.50 * 10 < ^-8 > (ohm) m or less is more preferable. The electrical resistivity R can be measured using an electrometer (product name “6517 B type electrometer”, manufactured by Keithley). The electrical resistivity R is an arithmetic mean 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 portion 44 is formed of copper foil, it is possible to achieve both heat dissipation and electrical conductivity at a high level. More specifically, since the heat dissipation from the LED element is stabilized and the increase in the electrical resistance can be prevented, the variation in light emission among the LEDs becomes small, and the stable light emission of the LED becomes possible. In addition, the lifetime of the LED element is also extended. Furthermore, since deterioration of peripheral members such as a resin film due to heat can be prevented, the product life of the image display device incorporating the surface light source device can also be extended.

  As an example of the metal which forms the metal wiring part 44, metals, such as aluminum, gold | metal | money, silver other than said copper, can be mentioned.

  The metal wiring portion 44 is an electrodeposited copper foil, and the ten-point average roughness Rz of the surface on the resin film 43 side of the metal wiring portion 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 on the resin film 43 side of the metal wiring portion 44 can be particularly increased, and the heat dissipation can be further enhanced. Moreover, since this surface is an uneven surface, the adhesion with the resin film 43 can be further improved, and the heat dissipation can also be improved by this. The rough side (mat surface side) of the electrodeposited copper foil can be suitably used as the surface of the electrodeposited copper foil having such a ten-point average roughness Rz. The ten-point average roughness Rz can be measured, for example, using a surface roughness measuring device (product name “SE-3400”, manufactured by Kosaka Laboratory Ltd.) in accordance with JIS B0601: 1999. The ten-point average roughness Rz is an arithmetic mean value of the values obtained by measuring three times.

  The arrangement of the metal wiring portion 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 metal wiring portion 44 preferably covers 80% or more, more preferably 90%, and most preferably 95% or more of one surface of the resin film 43. preferable. Thus, the LED elements 42 can be disposed at high density, and the generated excess heat can be sufficiently diffused quickly through the metal wiring portion 44 and can be dissipated to the outside via the resin film 43. Therefore, the surface light source device 20 having excellent heat dissipation can be obtained.

  The thickness of the metal wiring portion 44 may be appropriately set according to the magnitude of the current resistance required of the wiring substrate 41 and is not particularly limited, but may be 10 μm to 50 μm as an example. It is preferable that the thickness of the metal wiring part 44 is 10 micrometers or more from a viewpoint of heat dissipation improvement. In addition, if the thickness of the metal wiring portion is less than 10 μm, the thermal contraction of the resin film 43 is significant, and the warpage after the solder reflow process tends to be large. The length is preferably 10 μm or more. On the other hand, when the thickness of the metal wiring portion is 50 μm or less, sufficient flexibility of the wiring substrate can be maintained, and a decrease in handling property due to an increase in weight can be prevented. The thickness of the metal wiring portion 44 can be measured by the same method as the resin film 43.

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

  The insulating protective film 45 is preferably made 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 having 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, for example, a white thermosetting resin composition further containing an inorganic white pigment such as titanium dioxide. By whitening the insulating protective film 45, the design can be improved. Also, 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 film thickness of the insulating protective film 45 is less than 10 μm, there is a possibility that the insulating property may be lowered, and if it exceeds 100 μm, bleeding when forming the insulating protective layer by screen printing or shrinkage upon heat curing There is a possibility that warpage or the like of the wiring board due to may significantly occur. The film thickness of the insulating protective film 45 is obtained by photographing the cross section of the insulating protective film 45 using a scanning electron microscope (SEM), and measuring the film thickness of the insulating protective film 45 at 20 points in the image of the cross section. , The arithmetic mean value of the film thickness of the 20 places.

(Reflective layer)
The reflective layer 46 has high reflectivity mainly to light in the visible light wavelength range of wavelengths of 380 nm to 780 nm. The reflective layer 46 is stacked on the surface 41 A of the wiring board 41 so as to cover the area excluding the LED element mounting area, for the purpose of improving the light emitting capability of the surface light source device 20. In this embodiment, the reflective layer 46 insulates so as to surround the LED element 42 and to expose the inner peripheral edge of the area of the insulating protective film 45 removed by the LED element mounting area in plan view. It is laminated on the protective film 45. Further, the present invention is not limited to this. For example, the inner peripheral edge of the region of the insulating protective film 45 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 It may be laminated so as to match and make the same shape.

  The reflective layer 46 is not particularly limited as long as it is a member having a reflective surface for reflecting light from the LED element 42 and guiding it in a predetermined direction, but a foam type white polyester, white polyethylene resin, silver deposited polyester, etc. Can be used as appropriate depending on the application of the final product and its required specifications and the like.

  The film thickness of the reflective layer 46 is preferably 50 μm or more and 1 mm or less. If the film thickness of the reflective layer 46 is less than 50 μm, the desired reflectance may not be obtained, and the reflective layer is too thin, so it becomes difficult to set at a predetermined position, and if it exceeds 1 mm While it becomes cost, there exists a possibility that thickness reduction of a surface light source device can not be achieved. The film thickness of the reflective layer 46 can be measured by the same method as the film thickness of the insulating protective film 45.

(Adhesive layer)
As the adhesive layer 47, a known resin-based adhesive can be used as appropriate. Among 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 etching process of the metal wiring portion 44.

(Solder layer)
The solder layer 48 is for electrically and mechanically bonding the metal wiring portion 44 and the LED element 42. The bonding method using the solder layer 48 can be roughly divided into a reflow method and a laser method, but either of them can be used.

  When the metal wiring portion and the LED element are joined by solder, a large amount of heat is applied to the resin film and the metal wiring portion, and therefore, the resin film and the metal wiring portion are different from each other There is a possibility that warpage may occur in the wiring substrate 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 dissipated to the casing main body 31 more.

<< LED device >>
The LED element 42 is a light emitting element using light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. As the LED element, 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 a P-type and an N-type electrode are provided on one surface of the element are known. An LED element can also be used for the surface light source device 20. However, among the above, 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. In the present specification, "matrix-like" means a state in which the two-dimensional arrangement is made in a matrix-like manner. 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 zigzag. 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, preferably 0.1 pieces / cm ² or more and 1.5 pieces / cm ² or less More preferable.

<< First Optical Sheet >>
The first optical sheet 50 is a sheet having an optical function. As a 1st optical sheet, a light transmissive reflective sheet etc. are mentioned, for example. The first optical sheet 50 shown in FIGS. 1 and 2 is a light transmitting and reflecting sheet. The light transmitting / reflecting sheet has a transmitting portion for transmitting light and a reflecting portion for reflecting light, and transmits light at a certain portion and reflects light at the other portion, thereby making the light from the LED element in a plane. And have the function of improving the in-plane uniformity of the luminance.

  The first optical sheet 50 is disposed to face the plurality of LED elements 42 in the LED mounting substrate 40, and the first optical sheet 50 is attached to the LED mounting substrate 40 by the first spacer 60. Are separated. The first optical sheet 50 is disposed substantially parallel to the wiring substrate 41.

  The distance d1 from the surface 41A of the wiring board 41 to the first optical sheet 50 shown in FIG. 3 is 0.6 mm or more and 6 mm or less. The “distance from the surface of the wiring substrate to the first optical sheet” in the present specification includes a reflective layer on the insulating protective layer like the wiring substrate 41, and the surface of the reflective layer is the surface of the wiring substrate In this case, it means the distance from the surface of the reflective layer to the surface on the wiring substrate side of the first optical sheet, and the insulating protective layer of the wiring substrate also has the function of the reflective layer, When the surface of the conductive protective layer is the surface of the wiring substrate, it means the distance from the surface of the insulating protective layer to the surface of the first optical sheet on the wiring substrate side. In addition, the surface on the side of the wiring substrate in the first optical sheet is the surface on the side of the wiring substrate in the resin film when the surface on the side of the wiring substrate in the first optical sheet is composed of only the surface of the resin film. However, when the reflective layer 55 is formed closer to the wiring substrate 41 than 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 and reflecting sheet is less than 25 μm, a desired reflectance may not be obtained, and if it exceeds 1 mm, the surface light source device may not be thinned. The thickness of the first optical sheet 50 is the thickness of the reflecting portion 53 described later, and a cross section of the first optical sheet 50 is photographed using a scanning electron microscope (SEM), and the first image It can obtain | require by measuring the thickness of ten arbitrary places of the optical sheet 50, and calculating the average value. As shown in FIG. 4, the first optical sheet 50 is provided with a plurality of divided areas 51 in a plan view.

<Division area>
It is preferable that the division area 51 be divided in accordance with the number of LED elements 42. In FIG. 4, corresponding to the LED elements (4 vertical × 6 horizontal = 24), 4 vertical × 6 horizontal = 24 divided areas 51 are formed. Although the boundary line is described by a dotted line in FIG. 4, no boundary line is actually formed, and the boundary line is a virtual line, and the divided area 51 is also a virtual area.

  As shown in FIG. 4, each divided region 51 includes a plurality of transmitting portions 52 transmitting a part of light from the LED element 42 and a plurality of reflecting portions 53 reflecting a portion of light from the LED element 42. It consists of The transmitting unit 52 and the reflecting unit 53 are configured in a predetermined pattern. The portion corresponding to the LED element in each divided region is the portion to which the largest amount of light is incident, so if light is transmitted from this portion, the brightness of this portion will be higher than the brightness of the other portions of the divided region The in-plane uniformity of the luminance may be reduced. For this reason, it is preferable that the part corresponding to the LED element 42 in each division area 51 is comprised from the reflection part 53. FIG. In FIG. 4, the transmitting portion 52 is formally shown in white, and the reflecting portion 53 is shown in gray. Further, the patterns of the transmitting portion 52 and the reflecting portion 53 in each divided region 51 are the same, but they do not necessarily have to be the same and may be different patterns depending on the divided region. The transmitting part 52 and the reflecting part 53 may be a grid pattern.

  Since the first optical sheet 50 is disposed such that the central portion 51A of each divided region 51 corresponds to each LED element 42 as shown in FIG. 4, the first optical sheet 50 is closer to the central portion than the outer edge 51B. The amount of light incident on 51A increases. For this reason, in each divided region 51, it is preferable that the aperture ratio, which is the area ratio of the transmission portion 52, gradually increases from the central portion 51A toward the outer edge portion 51B. By gradually increasing the aperture ratio in each divided region 51 from the central portion 51A toward the outer edge portion 51B, it is possible to further improve the uniformity of the luminance on the light emitting surface while securing a sufficient amount of light. The “aperture ratio” of the sectioned area in the present specification means each mass when the sectioned area of one section is divided into square cells having an equal area equally divided by about 25 to 100 equally. It means the area ratio of the transmission part in the eye. The way of defining the squares of this equal area in one sectioned area is arbitrary, but it is desirable to set, for example, the number of transmission parts present in each square to be approximately equal. In addition, “aperture ratio” defines a plurality of concentric circles centered on the center point of one sectioned region at equal intervals from the central region to the outer region located outside the central region, and the circumference and circle of each concentric circle It may be determined by calculating the area ratio of the transmission part in each region between the circumference in the same manner as described above. According to this calculation method, the above-mentioned "aperture ratio" can be defined also for partition areas other than the general opening arrangement in which rectangular openings are arranged in a lattice. In each divided region 51, the aperture ratio may be gradually increased 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 divided region 51, the area ratio is preferably reflecting portion> transparent portion, and from the viewpoint of improving the in-plane uniformity of luminance, the central portion 51A of each divided region 51 is reflected It is more preferable to comprise only the part 53. Further, in the outer edge portion 51B of each divided region 51, it is preferable that the area ratio be transmission portion> reflection portion. Specifically, the area ratio of the transmission portion 52 in the outer edge portion 51B is preferably 50% or more and 100% or less. The lower limit of the area ratio of the transmission portion 52 in the outer edge portion 51B is more preferably 60% or more, and still more preferably 70% or more. In addition, by forming the reflecting portion 53 in an island shape at the outer edge portion 51B, the area ratio of the transmitting portion can be theoretically made 100%. This is a configuration that can not be achieved by the conventional light transmission and reflection sheet of the punching-aperture type. As described above, in the case where the transmission section 52 and the reflection section 53 of the first optical sheet 50 are patterned by the printing method, the patterning flexibility can be expanded.

  As shown in FIG. 3, the first optical sheet 50 is composed of a resin film 54 and a reflective layer 55 laminated on 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, the area where the reflective layer 55 exists becomes the reflective part 53, and the area where the reflective layer 55 does not exist becomes the transmissive part 52.

<Transparent part>
The transmitting portion 52 is a region in which the reflective layer 55 is not formed on any of both surfaces of the resin film 54, and is a region in which 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 can be measured using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory) in accordance with JIS K-7361: 1997. The total light transmittance is an arithmetic mean of the 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.

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

  The reflective portion 53 preferably has a reflectance of at least 80% or more in a visible light wavelength region of 420 nm or more and 780 nm or less. The reflectance of the reflection part formed in a narrow range like the reflection part 53 in the first optical sheet 50 is to use a microspectrometer (product name “USPM-RU III”, manufactured by Olympus Corporation) More accurate measurements can be made. The value of reflectance is a value obtained by measuring relative reflectance with barium sulfate as a standard plate and 100% of the standard plate. In addition, let a reflectance be an arithmetic mean value of the value obtained by measuring 3 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.

  As a thermosetting resin in the thermosetting resin composition which comprises the reflection layer 55, the combination of a conventionally well-known urethane resin and an isocyanate compound, the combination of an epoxy resin, a polyamine, and an acid anhydride, a silicone resin and a crosslinking agent Two-component thermosetting resins containing a main agent and a curing agent, as well as three-component thermosetting resins containing a curing accelerator such as amine, imidazole or phosphorus, as mentioned in combination with Be Specifically, as a thermosetting resin, the silicone-type thermosetting resin described in Unexamined-Japanese-Patent No. 2014-129549 is mentioned. 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 a reflectance are sum total thickness of both thickness, when the reflection layer is formed on both surfaces of a resin film, and is a reflectance in the state which formed the reflection layer on both surfaces.

  As described above, the first optical sheet 50 shown in FIG. 3 is composed of the resin film 54 and the reflective layer 55 laminated on a part of at least one surface of the resin film 54, Like the optical sheet described in the second embodiment, the first optical sheet is, for example, a plurality of openings penetrating in a thickness direction of the light reflective sheet to a light reflective sheet such as foamed polyethylene terephthalate (PET). It may be a first optical sheet in which Like the first optical sheet 50, the first optical sheet in which the opening is formed in the reflective sheet includes a sectioned area, a transmitting portion, and a reflecting portion. Since the sectioned area, the transmitting section, and the reflecting section in the first optical sheet having the opening formed in the reflective sheet are the same as the sectioned area 51, the transmitting section 52, and the reflecting section 53 in the first optical sheet 50 The explanation is omitted here. In each of the sectioned regions of the first optical sheet, it is preferable that the aperture ratio, which is the area ratio of the transmission part, gradually increases from the central portion of the sectioned region toward the outer edge of the sectioned region. In the case of the first optical sheet in which the opening is formed in the reflective sheet, the opening functions as a transmitting portion that transmits light, and a portion other than the opening in the first optical sheet reflects light. Act as a department. The openings have an arbitrary shape (for example, a circular shape or a rectangular shape), and are distributed so as not to be connected to each other along a predetermined pattern. The opening can be formed by press punching or punching with an engraving blade. Since press punching is excellent in running cost and productivity, it is an effective manufacturing method in mass production.

<< 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 substrate 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 sheet in a plan view of the first optical sheet The central part of the divided area may be brighter than the outer edge, and if it exceeds 5 mm, the surface light source device may not be thinned. In the present specification, “the height of the first spacer” means the bottom surface of the first spacer opposite to the bottom surface of the first spacer in the direction perpendicular to the bottom surface of the first spacer on the wiring substrate 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 mean value of values obtained by randomly measuring the height of the first spacer 60 at ten places.

  The first spacer 60 and the wiring board 41 are fixed. It does not specifically limit as a fixing method of the 1st spacer 60 and the wiring board 41, The fixing by adhesion | attachment or a mechanical fixing means is mentioned. "Adhesion" in the present specification is a concept including "stickiness". In FIG. 3, the first spacer 60 and the wiring board 41 are fixed via the double-sided adhesive tape 111. Specifically, the bottom surface 60A 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 the double-sided tape 111. By fixing the first spacer 60 and the wiring board 41, 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 substrate 41 may be fixed not using the double-sided tape 111 but using an adhesive or a pressure-sensitive adhesive. Although the first spacer 60 is fixed to the reflective layer 46 in FIG. 3, the first spacer 60 may be formed by forming a through hole in the reflective layer of the wiring substrate or by not providing the reflective layer on the wiring substrate. The first spacer may be fixed to the insulating protective film, and the through hole is formed in the reflective layer and the insulating protective layer of the wiring substrate, or the reflective layer and the insulating protective layer are not provided on the wiring substrate. Thus, the first spacer may be fixed to the metal wiring portion.

  The first spacer 60 and the first optical sheet 50 are fixed. The fixing method of the first spacer 60 and the first optical sheet 50 is not particularly limited, and fixing by adhesion or mechanical fixing means may be mentioned. In FIG. 3, the first spacer 60 and the first optical sheet 50 are fixed by being adhered via the double-sided tape 112. Specifically, the upper surface 60B of the first spacer 60 (the upper surface of the wall 62 described later) and the first optical sheet 50 are bonded via the double-sided adhesive tape 112. By fixing the first spacer 60 and the first optical sheet 50, positional deviation of the first optical sheet 50 with respect to the first spacer 60 and the LED element 42 can be further suppressed. The first spacer 60 and the first optical sheet 50 may be fixed using an adhesive or an adhesive instead of the double-sided tape 112.

  A first spacer includes a first portion extending in a first direction, and a wall portion including a second portion extending in a second direction different from the first direction and intersecting the first portion. And a light passing area which is present in an area other than the wall and which allows light to pass. In the present specification, “extending in the first direction” means that it is sufficient if the first portion extends in the first direction when the first portion is viewed generally, along the first direction. It does not have to be Similarly, “extending in the second direction” means that it is sufficient if the second portion extends in the second direction when the second portion is viewed generally, along the second direction. It does not have to be The first spacer 60, as shown in FIG. 5, divides the openings 61 as two or more light transmitting regions penetrating in the height direction of the first spacer 60 and the openings 61, and at least And a wall 62 surrounding the periphery of one opening 61.

<Aperture>
The openings 61 are for transmitting the light from the respective LED elements 42. The number of the openings 61 is not particularly limited, but in FIG. 5, the number of the openings is 4 × 6 = 24 corresponding to the number of LED elements 42 (4 × 6 = 24). The portion 61 is formed.

  Since each opening 61 is for transmitting the light from each LED element 42, each opening 61 has a size such that the LED element 42 enters the opening 61 when the first spacer 60 is viewed in plan. It has become. Although one LED element 42 is disposed in one opening 61 in FIG. 6, a plurality of LED elements may be disposed in one opening.

  The openings 61 shown in FIG. 5 are all the same size, but the openings 61 need not be the same size and may be of different sizes.

<Wall part>
The wall 62 has a first portion 63 extending in the first direction DR1 and a second portion 64 extending in the second direction DR2 different from the first direction DR1 and intersecting the first portion 63. Is equipped. The first portion 63 and the second portion 64 are components of the wall portion 62, and more specifically, are elements constituting a partition portion 66 described later that divides the openings 61. Although the first part and the second part intersect, the angle between the first part and the second part is 60 ° or more from the viewpoint of stably supporting the first optical sheet. Is preferred. In the present specification, “an angle formed by the first portion and the second portion” means the smaller one of the angles formed by the first portion and the second portion. Specifically, in the case of the first spacer 60, the angle between the first portion 63 and the second portion 64 is the angle represented by θ1 shown in FIG. 5, and the first spacer described later In the case of 140, the angle between the first portion 143 and the second portion 144 is the angle represented by θ1 shown in FIG.

  The wall 62 partitions the openings 61 and surrounds the periphery of the at least one opening 61 as described above. The wall 62 preferably surrounds the periphery of the two or more openings 61, and more preferably surrounds the periphery of all the openings 61. The walls 62 shown in FIG. 5 are in the form of a lattice and surround the periphery of all the openings 61. In the present specification, “lattice-like” means a structure in which a plurality of openings are arranged in a matrix by a wall in a plan view of the first spacer. Examples of the shape of the opening in plan view of the first spacer include a polygonal shape such as a quadrilateral shape, an elliptical shape, and a circular shape. Examples of the square shape include a square shape, a rectangular shape, and a rhombus shape. In the first spacer 60 shown in FIG. 5, rectangular openings 61 are arranged in a matrix by the wall 62. The wall 62 can be obtained by injection molding, cutting or a three-dimensional printer.

  The wall 62 is in the form of a grid, but the wall may not be in the form of a grid. For example, the wall portion may have the openings arranged in a staggered manner. Specifically, like the first spacer 140 shown in FIG. 7, the wall portion 142 may be in a honeycomb shape. Similarly to the first spacer 60, the first spacer 140 shown in FIG. 7 also has two or more openings 141 as light passing regions. The wall portion 142 includes a first portion 143 extending in the first direction DR1 and a second portion 144 extending in the second direction DR2 different from the first direction DR1 and intersecting the first portion 143. And the wall 142 partitions between the openings 141 and surrounds the periphery of the at least one opening 141. The first spacer 140 is the same as the first spacer 60 except that the wall portion 142 has a honeycomb shape, and thus the description thereof is omitted here. In addition, when using the LED mounting substrate 40 in which the LED elements 42 are arranged in a matrix, the first spacer 60 in which the wall portion 62 is in a grid is used, and the LED mounting in which the LED elements are arranged in a zigzag In the case of using a substrate, the first spacer 140 in which the wall portion 142 has a honeycomb shape can be used.

  Further, as in the first spacer 150 shown in FIG. 8, the corner 152 A on the opening 151 side of the wall 152 may be curved in a plan view of the first spacer 150. The corner 152A has a curved shape in plan view of the first spacer 150, so that the wall 152 is less likely to be broken even when vibration or impact is applied to the wall 152, and the corner Since the number of reflections in the portion 152A can be reduced, the reduction in luminance can be suppressed. Similarly to the first spacer 60, the first spacer 150 shown in FIG. 8 also has two or more openings 151 as light passing regions. The wall portion 152 has a first portion 153 extending in the first direction DR1 and a second portion 154 extending in the second direction DR2 different from the first direction DR1 and intersecting the first portion 153. And the wall 152 partitions between the openings 151 and surrounds the periphery of the at least one opening 151. The first spacer 150 is the same as the first spacer 60 except that the corner 152A of the wall 152 is curved, so the description will be omitted here.

  The wall 62 shown in FIG. 5 is composed of a frame 65 and a partition 66 located inside the frame 65 and partitioning the openings 61. The wall portion 62 includes the frame portion 65. For example, like the first spacer 160 shown in FIG. 9, the wall portion 162 does not include the frame portion, and a well girder formed only of the partition portion 165 It may be in the form of Similarly to the first spacer 60, the first spacer 160 shown in FIG. 9 also has two or more openings 161 as light passing regions. The wall portion 162 has a first portion 163 extending in the first direction DR1 and a second portion 164 extending in the second direction DR2 different from the first direction DR1 and intersecting the first portion 163. The wall portion 162 partitions the openings 161 and surrounds the periphery of the at least one opening 161. However, in FIG. 9, the wall portion 162 does not surround the periphery of the opening 161 present at the outermost periphery. The first spacer 160 is the same as the first spacer 60 except that the wall portion 162 is constituted only by the partition portion 165, and therefore the description thereof is omitted here.

(Frame part)
The frame portion 65 has a rectangular shape in plan view, but the shape of the frame portion can be appropriately changed in accordance with the shape of the LED mounting substrate and the like. The frame portion 65 is substantially the same size as the wiring board 41.

(Partial division)
The partition part 66 partitions between the openings 61. The partition 66 shown in FIG. 5 is preferably provided integrally with the frame 65. By integrally forming the partition portion 66 with the frame portion 65, it is possible to obtain a first spacer having no joint, and therefore, it is possible to perform the process of assembling the surface light source device more than forming the first spacer from a plurality of members. It is possible to simplify and reduce the risk of misalignment of the first optical sheet in the vibration test. In addition, since the first spacer does not have a joint, it is possible to reduce optical loss without light entering the joint. In the present specification, "provided integrally" means not only when there is no boundary between the frame and the partition, that is, when the frame and the partition are integrally formed, but also the partition Is a concept including the case where it is joined to the frame. In the first spacer 60, the frame 65 and the partition 66 are integrally formed. The partition 66 is preferably provided integrally with the frame 65 from the viewpoint of increasing the strength of the wall 62, but the partition may not be provided integrally with the frame.

  It is preferable that the partition part 66 is arrange | positioned in the position corresponding to the boundary part 51C between the division area 51, as FIG. 6 shows. In the present specification, “a boundary between divided regions” means a portion including a region assumed to be a boundary between divided regions from the pattern of the transmitting portion and the reflecting portion. 6 is a plan view of the first spacer 60 and the first optical sheet 50 from the LED element 42 side.

  The thickness of the wall portion 62 is preferably 0.2 mm or more and 10 mm or less. If the thickness of the wall 62 is 0.2 mm or more, the first optical sheet 50 can reliably function as a support, and if 10 mm or less, the diameter of the opening 61 is sufficient. Therefore, the reduction in luminance can be suppressed. "Thickness of the wall" in the present specification means the thickness of the thinnest part of the wall. The thickness of the wall 62 may not be all uniform. In addition, although the thickness of the frame part 65 and the partition part 66 which comprise the wall part 62 may be the same, it is not necessary to be the same. The lower limit of the thickness of the wall portion 62 is more preferably 0.5 mm or more.

  As shown in FIG. 3, the side surface 62A of the wall 62 facing the opening 61 has a large opening diameter of the opening 61 from the bottom surface 60A to the top surface 60B in the height direction of the first spacer 60. It is inclined to become. By forming the wall portion 62 having such a side surface 62A, it is possible to reflect the light emitted from the LED element 42 by the side surface 62A of the wall portion 62 and to guide it to the first optical sheet 50. Light can be emitted from the device 20 more efficiently. The first spacer 60 provided with the wall portion 62 having such a 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 fabrication. Also, the wall may be inclined such that the diameter of the opening increases from the top surface to the bottom surface of the first spacer.

  The side surface 62A of the wall 62 is preferably a rough surface. Specifically, for example, the arithmetic mean roughness Ra of the side surface 62A is preferably 0.1 μm to 100 μm. If Ra of the side surface 62A is 0.1 μm or more, diffuse reflection is increased, so that the in-plane uniformity of luminance can be further improved, and if 100 μm or less, the number of reflections does not increase too much. It can suppress that the frequency which 1 spacer 60 absorbs light increases, and can suppress the fall of the in-plane uniformity of brightness | luminance. Ra can be measured using a surface roughness measuring device (product name “SE-3400”, manufactured by Kosaka Research Institute, Ltd.) in accordance with JIS B0601: 1999. Ra is randomly measured at 10 points, and is taken as the arithmetic mean value of 10 points of measured Ra. The method for roughening the side surface 62A is not particularly limited, and examples thereof include a method in which the wall portion 62 contains particles described later, or a sand blast method.

  The wall portion 62 preferably has light reflectivity from the viewpoint of reflecting the light from the LED element 42 and guiding it to the first optical sheet 50. The material constituting the wall portion 62 is not particularly limited, but is preferably made of resin (first resin) from the viewpoint of easy molding and protection of the first optical sheet 50 and the like from impact. . Among the first resins, light reflective resins such as white resins are preferable from the viewpoint of guiding the light to the first optical sheet 50 by increasing the reflectance. The wall portion 62 preferably further includes particles in addition to the resin from the viewpoint of improving the light diffusibility. Moreover, since not only visible light but also ultraviolet light is emitted from the LED element 42, there is a possibility that members in the surface light source device 20 may be deteriorated by ultraviolet light. For this reason, it is preferable that the wall portion 62 further contain an ultraviolet absorber in addition to the resin in order to suppress the ultraviolet deterioration.

  The Young's modulus at 25 ° C. of the first resin is preferably 0.5 GPa or more and 5 GPa or less. If the Young's modulus of the first resin is less than 0.5 GPa, there is a possibility that the strength for fixing the wiring substrate or the first optical sheet can not be secured in the wall portion, and if it exceeds 5 GPa, a surface light source There is a possibility that the first spacer can not be bent when installing the device on a curved surface or the like. The lower limit of the Young's modulus at 25 ° C. of the first resin is more preferably 1 GPa or more, and the upper limit is more preferably 4 GPa or less.

  Examples of the first resin include polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), acrylonitrile-butadiene-styrene copolymer 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 can be mentioned. Among these, polycarbonate resins, ABS resins, ASA resins, ASA resins, AES resins, PMMA resins, polyacetal resins, or a mixture of two or more of these resins is preferable from the viewpoint of heat resistance and moldability.

Examples of the particles include inorganic particles. Examples of the inorganic particles include inorganic oxide particles such as silica, alumina, titania (TiO ₂ ), tin oxide, antimony-doped tin oxide (ATO), and zinc oxide fine particles. The particles are preferably contained in the first spacer 60 at a ratio of 10 parts by mass to 250 parts by mass with respect to 100 parts by mass of the first resin.

  It does not specifically limit as said ultraviolet absorber, A triazine type ultraviolet absorber and a benzotriazole type ultraviolet absorber are mentioned. Among these, triazine-based ultraviolet absorbers are preferable from the viewpoint of not absorbing light in the visible light region as much as possible, and capable of efficiently absorbing ultraviolet light and hardly causing yellowing even when used for a long period of time. As a commercial item of a triazine series ultraviolet absorber, BASF Corporation TINUVIN 1577 ED is mentioned, for example. Moreover, you may add a hindered amine light stabilizer etc. as needed.

The wall portion 62 preferably has an antistatic property. When dust adheres during manufacture or use of the surface light source device, it causes a failure, but the wall portion 62 having the antistatic property can suppress dust adhesion when manufacturing or using the surface light source device . Since the antistatic property can be expressed 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 / sq 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 K 6911: 2006. . The surface resistance value of the wall portion 62 is obtained by measuring the surface resistance value of the wall portion 62 randomly at ten places, and taking the measured surface resistance value at ten places as an arithmetic mean value of the surface resistance values. As a method of imparting antistatic property to the wall portion 62, a method of coating a composition containing an antistatic agent by spraying or immersion may be mentioned.

  Preferably, the glass transition temperature (Tg) of the wall 62 exceeds 85 ° C. When the surface light source device is incorporated into a vehicle such as a car, the wall portion 62 is heated at 85 ° C. for 1000 hours for 1000 hours because it is heated by the engine or the like. It is required not to 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 environmental test of leaving the wall portion 62 in an environment of 85 ° C. for 1000 hours is performed it can. Moreover, since heat more than an environmental test may be added in summer, when the summer is considered, it is more preferable that the glass transition temperature of the wall part 62 exceeds 115 degreeC. Here, since the surface light source device is very thin, the distance between the first optical sheet and the LED mounting substrate is very precisely designed, and if the wall portion flows, Since the distance between the first optical sheet and the LED mounting substrate changes, uneven brightness occurs, and the in-plane uniformity of the brightness decreases. From this, the heat resistance reliability of the wall portion 62 is very important. The glass transition temperature of the wall portion 62 is obtained by scraping 10 mg of the wall portion 62 into a sample, and using a differential scanning calorimeter (DSC), it is to be measured at a temperature rising rate of 5 ° C./min. The glass transition temperature of the wall portion 62 is an arithmetic mean value of the values measured three times. When two or more glass transition temperatures of the wall portion 62 are confirmed, the glass transition temperature of the lowest temperature is adopted as the glass transition temperature.

  The molding shrinkage of the wall portion 62 is preferably less than 1.0%. If the molding shrinkage ratio of the wall portion 62 is less than 1.0%, it is possible to suppress the dimensional change of the wall portion 62, the occurrence of warpage, and the like at the time of cooling after molding. The measurement of the molding shrinkage of the wall 62 is carried out according to JIS K 6911: 1995. When the molding shrinkage of the wall 62 is measured, the resin constituting the wall 62 by heating the wall 62 Are melted, the resin is poured into a mold, and a molded product obtained by solidification is used.

  Although the frame portion 65 and the partition portion 66 are integrally provided in the wall portion 62, the frame portion 65 and the partition portion 66 may not be integrally provided. That is, as in the first spacer 170 shown in FIG. 10A, the frame portion 175 and the partition portion 176 are separately manufactured, and the partition portion 176 is disposed inside the frame portion 175 to obtain the wall portion 172. May be Alternatively, as in the first spacer 180 shown in FIG. 10B, two or more wall portions 182A may be joined to obtain the wall portion 182. The first spacers 170 and 180 also have two or more openings 171 and 181 as light passing areas in addition to the walls 172 and 182, and the walls 172 and 182 have a first direction. A first portion 173, 183 extending in the DR1 and a second portion 174, 184 extending in the second direction DR2 and intersecting the first portion 173, 183 are provided.

  In the wall portion 62, the first portion 63 continuously extends in the first direction DR1, and the second portion 64 continuously extends in the second direction DR2. The part or the second part may be composed of a plurality of divided pieces. In the present specification, when the first part or the second part is composed of a plurality of divided pieces, a collection of a plurality of divided pieces arranged in the first direction is taken as the first part, A collection of a plurality of divided pieces aligned in the second direction is taken as a second part. When the first part or the second part is composed of a plurality of divided pieces, when the first part or the second part is viewed as an assembly of divided pieces, the first part and the second part It is only necessary that the two parts intersect, and the divided pieces constituting the first part and the divided pieces constituting the second part do not necessarily intersect.

  Examples of the first spacer in which the first portion and the second portion are formed of a plurality of divided pieces include, for example, FIG. 11 (A), FIG. 11 (B), FIG. 12 (A) and FIG. 12 (B). The first spacers 190, 200, 210, 220 shown in FIG. Similar to the first spacer 60, the first spacers 190, 200, 210, 220 respectively have the light passing regions 191, 201, 211, 221 and the first portions 193, 203 extending in the first direction DR1. , 213, 223 and a second portion 194, 204, 214, 224 which extends in a second direction DR2 different from the first direction DR1 and which intersects the first portion 193, 203, 213, 223. And the wall portion 192, 202, 212, 222 provided. In FIGS. 11A, 11B, 12A, and 12B, the first portions 193, 203, 213, 223 and the second portions 194, 204, 214, 224 is indicated by a two-dot chain line.

  In the first spacer 190 shown in FIG. 11A, the first part 193 is composed of a plurality of split pieces 193A, and the second part 194 is composed of a plurality of split pieces 194A, The divided pieces 193A and the divided pieces 194A directly intersect each other.

  In the first spacer 190, the distance from the first intersection point of an arbitrary divided piece 193A and divided piece 194A in the first direction D1 to the second intersection point of the adjacent divided piece 193A and divided piece 194A is 100. It is preferable that the division pieces 193A exist so that the ratio of the length occupied by the division pieces 193A is 50% or more between the first intersection point and the second intersection point when%. For example, the divided pieces 193A constituting the first intersection point extend 25% or more from the first intersection point toward the second intersection point, and the divided pieces 193A constituting the second intersection point are the second It is preferable that a length of 25% or more is extended from the point of intersection to the first point of intersection. By setting the length of the division pieces 193A to such a length, even when the first portion 193 is constituted of a plurality of division pieces 193, the contact area with the first optical sheet 50 is reduced. It can be suppressed. For the same reason, in the first spacer 190, the second intersection point of the adjacent divided piece 193A and the divided piece 194A from the first intersection point of the arbitrary divided piece 193A and the divided piece 194A in the second direction D2. The division piece 194A exists so that the ratio of the length occupied by the division piece 193A is 50% or more between the first intersection point and the second intersection point when the distance to 100 preferable. For example, the split piece 194A constituting the first intersection extends 25% or more from the first intersection to the second intersection, and the split piece 194A constituting the second intersection is the second It is preferable that a length of 25% or more is extended from the point of intersection to the first point of intersection.

  In the first spacer 200 shown in FIG. 11B, the first portion 203 is composed of a plurality of divided pieces 203A and 203B, and the second portion 204 is composed of a plurality of divided pieces 204A and 204B. It is done. The split pieces 203A and the split pieces 204A respectively directly intersect, but the split pieces 203B existing between the split pieces 203A do not cross the split pieces 204A and 204B, and the split pieces 204B exist between the split pieces 204A. Does not intersect the divided pieces 203A and 203B.

  Also in the first spacer 200, for the same reason as described above, from the first intersection point of an arbitrary split piece 203A and the split piece 204A in the first direction D1, the second of the next split piece 203A and the split piece 204A. Division pieces 203A such that the ratio of the total length occupied by the division pieces 203A and 203B between the first intersection point and the second intersection point is 50% or more, where the distance to the intersection point of 203B is preferably present, and a distance from a first intersection point of an arbitrary divided piece 203A and divided piece 204A in a second direction D1 to a second intersection point of an adjacent divided piece 203A and divided piece 204A The division pieces 204A and 204B exist such that the ratio of the total length occupied by the division pieces 204A and 204B is 50% or more between the first intersection point and the second intersection point, where A baby It is preferred.

  In the first spacers 210 and 220 shown in FIGS. 12A and 12B, the first portions 213 and 223 are respectively composed of a plurality of divided pieces 213A and 223A, and the second portions The portions 214, 224 are each composed of a plurality of split pieces 214A, 224A. Although the divided pieces 213A, 223A and the divided pieces 214A, 224A do not directly intersect, a first portion 213, 223 formed of an assembly of a plurality of divided pieces 213A, 223A arranged in the first direction DR1 and a second portion The second portions 214, 224 formed by an assembly of the plurality of divided pieces 214A, 224A arranged in the direction DR2 of FIG. In this specification, even if it can not be said that the divided pieces themselves extend in the first direction or the second direction as shown in FIG. 12 (B), the first portion and the second portion The first part is considered to extend in the first direction if there is at least one divided piece that does not constitute an intersection between any intersection point of and the next intersection point in the first direction. If there is at least one divided piece that does not constitute an intersection between an arbitrary intersection of the first portion and the second portion to the adjacent intersection in the second direction, the second portion is the second It shall be considered as extending in the direction.

  As described in detail in the second embodiment, a convex portion may be provided on the upper surface of the wall portion on the first optical sheet side. As described above, the first spacer can be manufactured by injection molding, punching, cutting, or a three-dimensional printer, but in the case where the first spacer is provided with a convex portion, among these, the convex may be formed. Injection molding is preferred from the viewpoint of ease of formation of the part.

  In the surface light source device, the first spacer having the wall portion is provided from the viewpoint of suppressing the bending of the first optical sheet, etc., but the wall portion has the ability to absorb light not a little. Therefore, light absorption occurs every time it reaches the wall, and it is affected by diffuse reflection by the particles contained in the wall to increase the reflectance, and it is more likely than columnar spacers or frame-like spacers. Also, the brightness may be reduced. For this reason, it is preferable to form an opening penetrating in the width direction of the partition in the partition from the viewpoint of improving the brightness. Specifically, as shown in FIGS. 13 (A), 13 (B), 14 (A) and 14 (B), the partitions 230, 240, 250, 260 are the first partitions. 231, 241, 251, 261 and a second partition 232, 242, 252, 262 adjacent to the first partition 231, 241, 251, 261, and a first partition 231, 241, 251, 261 And the second partitions 232, 242, 252, 262 and between the first partitions 231, 241, 251, 261 and the second partitions 232, 242, 252, 262 It may be provided with a third partition 233, 243, 253, 263 having openings 233A, 243A, 253A, 263A (hereinafter sometimes referred to simply as openings 233A, 243A, 253A, 263A). . The second partitions 232, 242, 252, 262 are separated from the first partitions 231, 241, 251, 261 via the openings 234, 244, 254, 264. By providing the openings 233A, 243A, 253A, 263A in the third partition parts 233, 243, 253, 263, part of the light emitted from the LED element 42 passes through the openings 233A, 243A, 253A, 263A. Since the light escapes to the side of the adjacent opening, light absorption by the third partitions 233, 243, 253, 263 can be further reduced, and the reduction in luminance can be further suppressed. The second opening may be a through hole or a notch. The openings 233A, 243A, 253A, 263A shown in FIG. 13A and the like are notches. The openings 233A, 243A, 253A, 263A are formed in the third partitions 233, 243, 253, 263, but the first partitions 231, 241, 251, 261 and the second partition 232 , 242, 252, 262 are preferably formed with the same openings as the openings 233A, 243A, 253A, 263A.

  As shown in FIGS. 13 (A), 13 (B), 14 (A) and 15 (B), the extending direction ED of the third partitions 233, 243, 253, 263 and the first spacer Of the third partitions 233, 243, 253, 263 and the openings 233A, 243A, 253A, 263A with respect to the total area AR (area surrounded by the two-dot chain line) It is preferable that the partition part opening ratio which is a ratio of the area of opening part 233A, 243A, 253A, 263A is 30% or more and 70% or less. If this partition part opening ratio is 30% or more, light absorption by the partition parts 230, 240, 250, 260 can be further suppressed, so that the brightness reduction can be further suppressed, and the partition part opening ratio is 70% or less For example, since the desired strength can be maintained, the first optical sheet 50 can reliably function as a support. The area of the third partition is the area from the intersection with the first partition to the intersection with the second partition, and as shown in FIG. In the case of a notch which is open in the height direction of the spacer of 1, the area of the second opening makes the flat plate contact the opening side of the second opening with respect to the first spacer , And the area of the space between the flat plate and the third partition. When the shape of the second opening provided in the third partition changes in the width direction of the third partition, the total area of the third partition and the second opening And the area of the second opening is a cross section where the area of the second opening is the smallest, and the total area of the third partition and the second opening and the area of the second opening are determined It shall be.

  In FIG. 13A, the opening 233A is located on the bottom surface 230A side of the partition 230, and the bottom 233B on the opening 233A side in the third partition 233 is planar. As shown in FIG. 13 (B), the bottom surface 243B of the third partition portion 243 on the side of the opening 243A may have, for example, a curved surface such as an arch shape. Further, as shown in FIGS. 14A and 14B, the openings 253A and 263A are located on the upper surface 250B and 260B side opposite to the bottom surfaces 250A and 260A of the partition 250 and 260, respectively. It is also good. Further, in FIG. 13A, the third partition 233 is provided with one opening 233A between the first partition 231 and the second partition 232, but the first partition Two or more openings may be provided between the portion and the second partition. Further, in FIG. 13A, in the above cross section, the opening 233A is formed so as to be symmetrical with respect to the center line of the opening 233A along the height direction of the spacer. It may be left-right asymmetry.

  At the intersection of the first portion and the second portion in the wall, the density of the first spacer is high, and the distance between the LED elements is large, so it tends to be dark. Therefore, from the viewpoint of improving the brightness in the vicinity of the intersection between the first part and the second part, the intersection is cut from the side of the first optical sheet, and as shown in FIG. It is preferable to form a notch 274 at the intersection with the second portion 273 so that two or more light transmission regions 271 in the light transmission region 271 adjacent to the intersection are partially connected. By forming such a notch 274 at the intersection of the first portion 272 and the second portion 273, light can be emitted from the intersection as well, thereby improving the brightness in the vicinity of the intersection. Can.

<< 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 arranging 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 the luminance is further increased. It 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 reflective polarization separation sheet, a reflective polarization separation sheet 100 may not be provided. When a lens sheet or a reflective polarization separation sheet is used as the second optical sheet, the same one as the lens sheet 90 or the reflective polarization separation sheet 100 can be used.

  The second optical sheet 70 is disposed on the light emitting 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 in parallel with 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 it exceeds 5 mm, there is a possibility that the surface light source device can not be thinned. In the present specification, “the distance from the first optical sheet to the second optical sheet” means the first optical sheet side of the second optical sheet from the surface of the first optical sheet side of the second optical sheet Shall mean the distance to the plane of The distance from the first optical sheet 50 to the second optical sheet 70 is an arithmetic mean value of values obtained by randomly measuring this distance at 10 points.

  From the viewpoint of reducing the thickness of the surface light source device, the distance d2 is preferably 2 mm or less (including 0 mm). However, in this case, the light diffusion function of the first optical sheet is not sufficiently exhibited, and the portion corresponding to the upper surface of the first spacer is darker than the other portions when the second optical sheet is viewed in plan. There is a risk of becoming Therefore, when the distance d2 is set to 2 mm or less, the side surface 62A facing the opening 61 of the wall portion 62 of the first spacer 60 is from the bottom surface 60A to the top surface 60B in the height direction of the first spacer 60. It is preferable to incline so that the diameter of the opening 61 of the opening 61 becomes larger. By the side surface 62A of the first spacer 60 being inclined in this manner, it is possible to suppress that the part corresponding to the upper surface 60B of the first spacer 60 becomes darker than the other parts. When the distance d2 is 2 mm or less (including 0 mm), the ratio of the width of the top surface 60B to the width of the bottom surface 60A of the first spacer 60 (width of the top surface / width of the bottom surface) is 0.95 or less Is preferable, and 0.3 or less is more preferable. From the viewpoint of stably supporting the first optical sheet 50, the lower limit of this ratio is preferably 0.1 or more.

  The distance (OD) from the surface 41A of the wiring substrate 41 to the second optical sheet 70 is preferably 1 mm or more and 10 mm or less from the viewpoint of achieving thinning of the surface light source device 20. The “distance from the surface of the wiring substrate to the second optical sheet” in this specification means the distance from the surface of the wiring substrate to the surface of the second optical sheet on the wiring substrate side. The distance from the surface 41A of the wiring board 41 to the second optical sheet 70 is an arithmetic mean value of values obtained by randomly measuring 10 points of this distance. 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 more difficult to bend than the first optical sheet 50. Therefore, the second optical sheet 70 can maintain 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. If the thickness of the second optical sheet 70 is less than 0.3 mm, the light diffusion effect may not be sufficiently obtained. If the thickness exceeds 5 mm, the surface light source device can be thinned. It 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 resin. In the present specification, "made of a resin" means that the resin is a main component. The second optical sheet 70 is, for example, a minute and random for exhibiting a light diffusing function, which is formed on one surface side of a semitransparent resin film made of polycarbonate resin, acrylic resin or the like, and the resin film. And a lens layer having a lens array and the like.

<< Second Spacer >>
The second spacer 80 is for separating the second optical sheet 70 from the first optical sheet 50. Further, the second spacer 80 holds the distance d2 from the first optical sheet 50 to the second optical sheet 70 at 0.5 mm or more and 5 mm or less, and the second optical sheet from the surface 41A of the wiring substrate 41 It has the function of holding the distance to 70 at 1 mm or more and 10 mm or less.

  The height h 2 of the second spacer 80 shown in FIG. 3 is larger than the height h 1 of the first spacer 60. The height h2 of the second spacer 80 is preferably 1 mm or more and 10 mm or less. If the height of the second spacer is less than 1 mm, the distance between the first optical sheet and the second optical sheet is too short, so in plan view of the second optical sheet, the first optical sheet There is a possibility that the part corresponding to the central part of each divided area becomes brighter than the part corresponding to the outer edge part, and if it exceeds 10 mm, there is a possibility that the surface light source device can not be thinned. In the present specification, “the height of the second spacer” means the height of the second spacer from the bottom surface of the second spacer in the direction perpendicular to the bottom surface which is the surface on the inner bottom side of the housing in the second spacer. It means the distance to the top surface. The height h2 of the second spacer 80 is an arithmetic mean value of values obtained by randomly measuring the height of the second spacer 80 at ten places.

  The second spacer 80 has a frame shape as shown in FIG. In the “frame shape” in the present specification, not only a configuration in which there is no gap but one round connection, there may be gaps in the middle as long as they are almost 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 50A of the first optical sheet 50 and the outer peripheral surface 60C of the first spacer 60. As shown in FIG. 2, the second spacer 80 surrounds not only the outer peripheral surface 50A of the first optical sheet 50 and the outer peripheral surface 60C of the first spacer 60 but also the outer peripheral surface 41C of the wiring substrate 41. It is arranged. 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 is shaped like a frame, light transmitted through the first optical sheet 50 and directed to the second spacer 80 side is reflected by the second spacer 80, and the second optical It can be led to the seat 70. In addition, by forming the second spacer 80 in a frame shape, the contact area with the second optical sheet 70 can be increased as compared to the case where the second spacer is formed of a plurality of columnar bodies. Since this can be done, the heat of the second optical sheet 70 can be further dissipated through the second spacer 80 when the surface light source device 20 is used. Further, since the second spacer 80 has a frame shape, adhesion between the second spacer 80 and the second optical sheet 70 is more than in the case where the second spacer is formed of a plurality of columnar bodies. Since the area can be increased, the second optical sheet 70 is less likely to be misaligned.

  As shown in FIG. 3, the bottom surface 80 </ b> B of the second spacer 80 is preferably in contact with the inner bottom surface 30 </ b> B of the housing 30. In the present 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. The concept includes a case in which a substantially negligible layer such as double-sided tape, adhesive or adhesive is interposed between the bottom surface of the spacer and the inner bottom surface of the housing. In FIG. 3, a double-sided adhesive tape 113 described later is interposed between the bottom surface 80 </ b> B of the second spacer 80 and the inner bottom surface 30 </ b> B of the housing 30.

  Further, an outer side surface 80C which is an 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 the surface opposite to the inner surface that defines the opening of the second spacer. Also, "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 Also, the concept includes a case where a substantially negligible layer such as double-sided tape, adhesive, or 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 </ b> C of the second spacer 80 is in direct contact with the inner side surface 30 </ b> D of the housing 30.

  The second spacer 80 and the housing 30 are preferably fixed from the viewpoint of further suppressing the positional deviation of the second optical sheet 70 with respect to the LED element 42. It does not specifically limit as a fixing method of the 2nd spacer 80 and the housing | casing 30, The fixing by adhesion | attachment or a mechanical fixing means is mentioned. In FIG. 3, the bottom surface 80 </ b> B of the second spacer 80 and the inner bottom surface 30 </ b> B of the housing 30 are fixed by being bonded via the double-sided adhesive tape 113. Here, since the second spacer 80 has a frame shape, the bonding area with the housing 30 can be increased compared to the case where the second spacer is formed of a plurality of columnar bodies. , Easy to fix the second spacer 80. The second spacer 80 and the housing 30 may be bonded not via the double-sided tape 113 but via an adhesive or a pressure-sensitive adhesive.

  The second spacer 80 and the second optical sheet 70 are preferably fixed. The fixing method of the second spacer 80 and the second optical sheet 70 is not particularly limited, and fixing by adhesion or mechanical fixing means can be mentioned. In FIG. 3, the upper surface 80D opposite to the bottom surface 80B of the second spacer 80 and the second optical sheet 70 are fixed by being bonded via the double-sided adhesive tape 114. By fixing the second spacer 80 and the second optical sheet 70, positional deviation of the second spacer 80 with respect to the LED element 42 can be further suppressed. 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 80E, which is the inner side surface of the second spacer 80, increases in the diameter of the opening 81 from the inner bottom surface 30B of the housing 30 toward the second optical sheet 70. It is preferable to be inclined. By forming the second spacer 80 having such an inner side surface 80E, the light emitted from the first optical sheet 50 is reflected by the inner side surface 80E of the second spacer 80, and the second optical sheet 70 is formed. Thus, light can be emitted from the surface light source device 20 more efficiently. The second spacer 80 having such an inner surface 80E can be obtained, for example, by 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 fabrication.

  The second spacer 80 preferably has light reflectivity from the viewpoint of reflecting the light from the LED element 42 and guiding it to the second optical sheet 70. The material forming the second spacer 80 is not particularly limited, but it is made of resin (second resin) from the viewpoint of easy molding and protection of the second optical sheet 70 and the like from impact. Is preferred. Among the second resins, light reflective resins such as white resins are preferable from the viewpoint of increasing the reflectance and guiding the light to the second optical sheet 70 more.

  It is preferable that the 2nd resin which comprises the 2nd spacer 80 is the same resin as the 1st resin which comprises the 1st spacer 60. As shown in FIG. However, at present, it is desirable to bend the surface light source device, and when the first spacer and the second spacer are made of a resin having a low Young's modulus in order to bend the surface light source device, Since the rigidity decreases, when the surface light source device is bent, the temperature of the second resin forming the second spacer 80 is set to 25 ° C. so that the surface light source device can be bent while maintaining a certain degree of rigidity. The Young's modulus of the first spacer 60 is preferably smaller than the Young's modulus at 25 ° C. of the first resin constituting the first spacer 60. The Young's modulus at 25 ° C. of the first resin constituting the first spacer 60 and the Young's modulus at 25 ° C. of the second resin constituting the second spacer 80 are respectively dynamic viscoelasticity measuring devices (product The tensile test is carried out at 25 ° C using the name “Rheogel-E4000” (manufactured by UBM Co., Ltd.). Do. In addition, let the said Young's modulus be an 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 the incident light and emitting the light from the light output side. As shown in FIG. 17, the lens sheet 90 has a function to intensively improve the luminance in the front direction by changing the traveling direction of light having a large incident angle such as L1 and emitting the light from the light output side. For example, it has a function (retroreflection function) of reflecting light having a small incident angle such as L2 and returning it to the second optical sheet 70 side, as well as the optical function. The lens sheet 90 is provided with a resin film 91 and a lens layer 92 provided on one surface of the resin film 91, as shown in FIG. The lens sheet 90 is disposed so that the lens layer 92 is positioned closer to the reflective polarization splitting sheet 100 than the resin film 91.

(Resin film)
As a constituent material of the resin film 91, for example, polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, polymethyl Thermoplastic resins such as pentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, or polyurethane can be mentioned.

(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 hemispherical shape. Specifically, a unit prism, a unit cylindrical lens, a unit micro lens etc. are mentioned as a unit lens. In addition, as a lens sheet which has such a unit lens shape, a prism sheet, a lenticular lens sheet, a microlens sheet etc. are mentioned.

  The unit lens 92A preferably has an apex angle θ2 of 80 ° to 100 °, and more preferably about 90 °, from the viewpoint of improving the utilization efficiency of light.

<Reflective type polarization separation sheet>
Of the light emitted from the lens sheet 90, the reflective polarization separation sheet 100 transmits only a first linear polarization component (for example, P polarization), and a second straight line orthogonal to the first linear polarization component. It has a function of reflecting a polarized light component (for example, S-polarized light) without absorbing it. The second linearly polarized light component reflected by the reflection type polarization separation sheet 100 is reflected again and depolarized (in a state including both the first linearly polarized light component and the second linearly polarized light component), Again, the light is incident on the reflective polarization separation sheet 100.

  As the reflective polarization separation sheet 100, “DBEF” (registered trademark) available from 3M can be used. In addition to the “DBEF”, a high brightness polarizing sheet “WRPS” available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarizing separation sheet 100.

  According to the present embodiment, the first spacer 60 extends in the first direction DR1 and the second portion 64 extends in the second direction DR2 and intersects the first portion 63. Since the wall portion 62 is provided, the contact area with the first optical sheet 50 can be increased as compared with a columnar spacer or a mere frame-like spacer. Thereby, the bending of the first optical sheet 50 can be suppressed. In addition, the wall portion 62 of the first spacer 60 partitions the openings 61 and surrounds the periphery of the at least one opening 61, so the contact area with the first optical sheet 50 is further increased. Can.

  When the first optical sheet is a light transmitting / reflecting sheet, since the light transmitting / reflecting sheet has a pattern of the transmitting portion and the reflecting portion in each section area, the light transmitting / reflecting sheet is bent by bending. Since the position of the light transmitting / reflecting sheet with respect to the element changes, the in-plane uniformity of luminance may be reduced. For this reason, the distance from the surface of the wiring substrate to the light transmitting and reflecting sheet needs to be maintained at a predetermined distance. In the present embodiment, the first spacer 60 can suppress the deflection of the first optical sheet 50 which is a light transmitting / reflecting sheet, so that the in-plane uniformity of luminance can be improved.

  According to this embodiment, since the first spacer 60 includes the wall portion 62, the rigidity is higher than that of the columnar spacer or the simple frame-like spacer. For this reason, when a vibration test is performed on the surface light source device 20, the swing width of the first optical sheet 50 is smaller than in the case where a columnar spacer or a simple frame-like spacer is used. Thereby, when a vibration test is performed, position shift of the 1st optical sheet 50 with respect to the LED element 42 can be suppressed. In addition, since the first spacer 60 is higher in rigidity than a columnar spacer or a simple frame-like spacer, the first spacer 60 is less likely to be damaged even when a vibration test is performed.

  In the case where the first optical sheet is a light transmitting / reflecting sheet, the light transmitting / reflecting sheet has a pattern of a transmitting portion and a reflecting portion in each sectioned area, so positional deviation of the light transmitting / reflecting sheet occurs. Since the position of the light transmitting / reflecting sheet with respect to the LED element changes, the in-plane uniformity of the luminance may be reduced. On the other hand, in the present embodiment, since the positional deviation of the first optical sheet 50 with respect to the LED element 42 can be suppressed, the in-plane uniformity of the luminance can be improved.

  When the housing and the first spacer are integrated, it is necessary to arrange individual LED mounting substrates in the opening of the first spacer, and it is necessary to electrically connect the respective LED mounting substrates. It takes a lot of time to arrange the LED mounting substrate. On the other hand, in the present embodiment, since the first spacer 60 is separate from the casing 30, one LED mounting substrate 40 on which a plurality of LED elements are mounted can be used. . As a result, it is not necessary to arrange a plurality of LED mounting boards, and it is not necessary to electrically connect the LED mounting boards, so the arrangement of the LED mounting boards is facilitated.

  When the first optical sheet is a light transmitting / reflecting sheet, as described above, the distance from the surface of the wiring substrate to the light transmitting / reflecting sheet needs to be maintained at a predetermined distance, but the housing and the first spacer When integrated, the distance from the surface of the wiring substrate to the first optical sheet may be changed depending on the thickness of the wiring substrate. On the other hand, in the present embodiment, since the first spacer 60 is separate from the casing 30 and the first spacer 60 is disposed on the wiring board 41, the thickness of the wiring board 41 is different. Instead, the distance d1 from the surface 41A of the wiring substrate 41 to the first optical sheet 50 can be maintained at a desired distance.

  Also in the first spacers 140, 150, 160, 170, 180, 190, 200, 210, 220, first portions 143, 153, 163, 173, 183, 193, 203, 213 extending in the first direction DR1. , 223, and a second portion 144, 154, 164, 174, 184 that extends in the second direction DR2 and intersects the first portion 143, 153, 163, 173, 183, 193, 203, 213, 223. 194, 204, 214, 224, and the wall portion 142, 152, 162, 172, 182, 192, 202, 212, 222 is provided so that the same effect as the first spacer 60 can be obtained. it can.

Second Embodiment
Hereinafter, a spacer, a direct-type surface light source device and an image display device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 18 is an exploded perspective view of the image display device according to the present embodiment, FIG. 19 is a schematic configuration diagram of the image display device according to the present embodiment, and FIG. 20 is a part of the surface light source device according to the present embodiment. FIG. 21 is a plan view of the first optical sheet shown in FIG. 18, FIG. 22 is a plan view of the first spacer shown in FIG. 18, and FIG. 23 is a first optical sheet shown in FIG. It is a top view which shows the arrangement | positioning relationship of and the 1st spacer. In FIG. 18 and the like, members denoted with the same reference numerals as those in FIG. 1 and the like are the same as the members illustrated in FIG.

<<<< image display device >>>>
The image display apparatus 300 shown in FIG. 19 and FIG. 20 includes a direct surface light source device 310 and a display panel 120 disposed closer to the viewer than the surface light source device 310.

<<< Area light source device >>>
The surface light source device 310 shown in FIG. 19 or FIG. 20 includes the housing 30, the LED mounting substrate 40, the first optical sheet 320, the first spacer 330, the second optical sheet 70, and the second The spacer 80 is provided. In addition, the surface light source device 310 further includes a lens sheet 90 and a reflective polarization separation sheet 100 laminated on the second optical sheet 70. The surface light source device 310 may include the LED mounting substrate 40, the first optical sheet 320, and the first spacer 330, and the housing 30, the second optical sheet 70, the second spacer 80, The lens sheet 90 or the reflective polarization separation sheet 100 may not be provided. The first spacer 330 is used in a surface light source device including an optical sheet and an LED mounting substrate facing the optical sheet. In the surface light source device 310, the optical sheet is the first optical sheet 320.

<< First Optical Sheet >>
The first optical sheet 320 is a sheet having an optical function. As a 1st optical sheet, a light transmissive reflective sheet etc. are mentioned, for example. The first optical sheet 320 shown in FIGS. 19 and 20 is a light transmitting and reflecting sheet.

  The first optical sheet 320 is disposed to face the plurality of LED elements 42 in the LED mounting substrate 40, and the first optical sheet 320 is attached to the LED mounting substrate 40 by the first spacer 330. Are separated. The first optical sheet 320 is disposed substantially parallel to the wiring substrate 41. The distance d1 from the surface 41 of the wiring board 41 to the first optical sheet 320 shown in FIG. 21 is 0.6 mm or more and 6 mm or less.

  The first optical sheet 320, as shown in FIG. 20, has at least one or more holes 320A in the surface of the first optical sheet 320 on the side of the first spacer 330. The convex part 335 mentioned later intrudes into the hole 320A. In the present embodiment, since the first optical sheet 320 has the plurality of openings 324 functioning as the transmission part 322, one or more of the openings 324 of the openings 324 are used as the holes 320A. There is. In the present embodiment, since the opening 324 is a through hole, the hole 320A is also a through hole. However, when a hole is provided separately from the opening 324, the hole is a through hole. It does not have to be. The "hole" in the present specification is a concept including not only a through hole but also a non-through hole such as a recess. Moreover, even if it is an optical sheet which does not have the opening part which functions as a permeation | transmission part, it is applicable if it is an optical sheet which has a hole which lets the convex part 335 enter.

  The thickness of the first optical sheet 320 is preferably 25 μm or more and 1 mm or less for the same reason as the first optical sheet 50. The thickness of the first optical sheet 320 is assumed to be the thickness of the reflecting portion 323 described later, and is measured by the same method as the thickness of the first optical sheet 50. As shown in FIG. 21, the first optical sheet 320 is provided with a plurality of divided areas 321 in a plan view.

<Division area>
It is preferable that the division area 321 be divided according to the number of LED elements 42. In FIG. 21, corresponding to the LED elements (4 vertical × 6 horizontal = 24), 4 vertical × 6 horizontal = 24 divided regions 321 are formed. In FIG. 21, although the boundary line is described by a dotted line, no boundary line is actually formed, the boundary line is a virtual line, and the divided area 321 is also a virtual area.

  Each divided region 321 includes a plurality of transmitting portions 322 transmitting a portion of light from the LED element 42 and a plurality of reflecting portions 323 reflecting a portion of light from the LED element 42, as shown in FIG. It consists of Similar to the transmitting unit 52 and the reflecting unit 53, the transmitting unit 322 and the reflecting unit 323 are configured in a predetermined pattern.

  In each divided area 321, for the same reason as the reason described in the section of the divided area 51, the aperture ratio, which is the area ratio of the transmission part 322, gradually increases from the central part 321A toward the outer edge part 321B. preferable. By gradually increasing the aperture ratio in each divided region 321 from the central portion 321A toward the outer edge portion 321B, it is possible to further improve the uniformity of the luminance on the light emitting surface while securing a sufficient amount of light.

  In the central portion 321A of each divided region 321, the area ratio is preferably reflecting portion> transparent portion, and from the viewpoint of improving the in-plane uniformity of luminance, the central portion 321A of each divided region 321 is reflected It is more preferable to comprise only the part 323. In addition, in the outer edge portion 321B of each divided region 321, it is preferable that the area ratio be transmission portion> reflection portion. Specifically, the area ratio of the transmission part 322 in the outer edge part 321B is preferably 50% or more and 100% or less. The lower limit of the area ratio of the transmission portion 322 in the outer edge portion 321B is more preferably 60% or more, and preferably 70% or more.

  The reflective portion 323 preferably has a reflectance of at least 80% or more in a visible light wavelength region of 420 nm or more and 780 nm or less. The reflectance of the reflective portion 323 is measured by the same method as the reflectance of the reflective portion 53.

  The first optical sheet 320 is, for example, a sheet having reflectivity such as foamed polyethylene terephthalate (PET), and has a plurality of openings 324 penetrating in the thickness direction of the first optical sheet 320. The opening 324 functions as a transmitting portion 322 which transmits light, and a portion of the first optical sheet 320 other than the opening 324 functions as a reflecting portion 323 which reflects light. The openings 324 have an arbitrary shape (for example, a circular shape or a rectangular shape), and are distributed so as not to be connected to each other along a predetermined pattern. The opening 324 can be formed by press punching, punching by an engraving blade, or the like. Since press punching is excellent in running cost and productivity, it is an effective manufacturing method in mass production.

<< First Spacer >>
The first spacer 330 is for separating the first optical sheet 320 from the LED mounting substrate 40. Further, the first spacer 330 has a function of holding the distance d1 from the surface 41A of the wiring substrate 41 to the first optical sheet 320 at 0.6 mm or more and 6 mm or less.

  The height h1 of the first spacer 330 shown in FIG. 20 is preferably 0.5 mm or more and 5 mm or less for the same reason as the reason described in the section of the first spacer 60. The height h1 of the first spacer 330 is an arithmetic mean value of values obtained by randomly measuring the height of the first spacer 330 at ten places.

  The first spacer 330 and the wiring substrate 41 are fixed by the same method as the method of fixing the first spacer 60 and the wiring substrate 41. In FIG. 20, the first spacer 330 and the wiring substrate 41 are fixed via the double-sided adhesive tape 111. By fixing the first spacer 60 and the wiring substrate 41, positional deviation of the first optical sheet 320 with respect to the LED element 42 can be further suppressed.

  The first spacer 330 and the first optical sheet 320 are preferably fixed by the same method as the method of fixing the first spacer 60 and the first optical sheet 50. In FIG. 20, the first spacer 330 and the first optical sheet 320 are fixed by being adhered via the double-sided tape 112. By fixing the first spacer 330 and the first optical sheet 320, positional deviation of the first optical sheet 320 with respect to the first spacer 330 and the LED element 42 can be further suppressed.

  The first spacer 330 has openings 331 as two or more light transmitting regions penetrating in the height direction of the first spacer 330, a first portion 333 extending in the first direction DR1, and a first A wall 332 having a second portion 334 extending in a second direction DR2 different from the direction DR1 and intersecting the first portion 333 and a surface 332A of the wall 332 on the first optical sheet 320 side And one or more convex portions 335 provided. The wall 332 partitions between the openings 331 and surrounds the periphery of the at least one opening 331. The "convex part" in the present specification is a concept including a protrusion. The first spacer 330 is aligned with the first optical sheet 320 as shown in FIG.

<Aperture>
Since the opening 331 is similar to the opening 61, the description will be omitted here.

<Wall part>
The wall 332 includes the first portion 333 and the second portion 334 as described above. The first portion 333 and the second portion 334 are components of the wall portion 332, and more specifically, are elements constituting a partitioning portion 337 described later that partitions the openings 331. Similar to the wall 62, the wall 332 shown in FIG. 22 is composed of a frame 336 and a partition 337 located inside the frame 336 and partitioning the openings 331. The wall portion 332, the frame portion 336, and the partition portion 337 are the same as the wall portion 62, the frame portion 65, and the partition portion 66, and thus the description thereof is omitted here. In addition, if the first spacer wall portion of the present embodiment also includes the first portion and the second portion, the wall portions 142, 152, 162, 172, 182, 192, 202, 202, 212, 222 It may have the same shape.

<Convex part>
The convex portion 335 is for aligning the position of the first optical sheet 320 with respect to the LED element 42 and suppressing positional deviation of the first optical sheet 320. The protrusion 335 enters the opening 324 functioning as the hole 320A.

  The shape of the convex portion 335 is not particularly limited, and examples thereof include, for example, a conical 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 320, the height of the convex portion 335 is preferably equal to or less than the thickness of the first optical sheet 320 (equal to or less than the height of the opening 324). Further, from the viewpoint of suppressing the positional deviation of the first optical sheet 320, the lower limit of the height of the convex portion 335 is more preferably at least 1/4 of the thickness of the first optical sheet 320.

  The diameter and width of the convex portion 335 are not particularly limited, but the first optical sheet 320 enters the opening 324 smaller than the target opening 324 because there are a plurality of openings with different diameters. It is preferred that the diameter not be such.

  The number of the convex portions 335 may be one or more as the whole of the first spacer 330, but it is preferable that a plurality of the convex portions 335 be formed from the viewpoint of suppressing the positional deviation of the first optical sheet 320. Furthermore, from the viewpoint of further suppressing the positional deviation of the first optical sheet 320, in a plan view of the first spacer 330, the convex portions 335 are formed in at least four places so that quadrilaterals are drawn by the convex portions 335. Is preferred.

  The convex portion 335 is integrally provided with the frame portion 336 and the partition portion 337. The first spacer 330 having the convex portion 335 can be manufactured by injection molding, cutting or a three-dimensional printer. In addition, although it is possible to separately manufacture the convex portion and fix the convex portion to at least one of the frame portion and the partition portion by an adhesive or the like or mechanical fixing, the convex portion may be fixed by the adhesive or the like. In the case where the projection is fixed to the partition and / or the partition, the projection may be separated from the frame and / or the partition, so the projection and the frame and / or the partition should be integrally formed by injection molding or the like. Is preferred.

  According to the present embodiment, the hole 320A is provided in the first optical sheet 320, and the convex portion 335 is provided in the first spacer 330. Therefore, the alignment of the first optical sheet 320 with respect to the LED element 42 can be performed. Even if the impact is applied to the surface light source device due to the vibration of the vehicle or the like or any other factors, the positional deviation of the first optical sheet 320 with respect to the LED element 42 can be suppressed. . In addition, since the first spacer 330 includes the wall portion 332 including the first portion 333 and the second portion 334 intersecting with the first portion 333, it is more rigid than the columnar spacer. high. For this reason, even when an impact is applied to the surface light source device 310 due to a vibration of a vehicle or the like or some other factor, the swing width of the first optical sheet 320 becomes smaller than when the columnar spacer is used. Therefore, positional deviation of the first optical sheet 320 with respect to the LED element 42 can be suppressed. Further, since positional deviation of the first optical sheet 320, which is a light transmitting / reflecting sheet, with respect to the LED element 42 can be suppressed, in the case where an impact is applied to the surface light source device 310 due to vibration of a vehicle or the like. Even if it is present, it is possible to suppress a decrease in in-plane uniformity of luminance. In the same manner as described above, when the second optical sheet 70 is provided with a hole and the second spacer 80 is provided with a projection, the positioning of the second optical sheet 70 with respect to the LED element 42 is facilitated. Misalignment of the second optical sheet 70 with respect to V.42 can be suppressed.

  In a surface light source device for vehicle use, it is required that the positional deviation of the first optical sheet with respect to the LED element, the first spacer, and the like are not broken even when the vibration test is performed. On the other hand, according to the present embodiment, the first optical sheet 320 is provided with the hole 320A, the first spacer 330 is provided with the convex portion 335, and the first spacer 330 is provided with the first portion 333 , And the second portion 334 intersecting with the first portion 333. Therefore, even when a vibration test is performed, the positional deviation of the first optical sheet 320 with respect to the LED element 42 Can be suppressed. In addition, since the first spacer 330 is higher in rigidity than the columnar spacer, the first spacer 330 is less likely to be damaged even when a vibration test is performed. Therefore, the surface light source device 310 can be suitably used for in-vehicle applications.

  In addition, when a plurality of columnar spacers are used as a spacer for separating the first optical sheet from the LED mounting substrate, the optical sheet may be bent at the central portion of the optical sheet. In particular, when the optical sheet is a light transmitting / reflecting sheet, the light transmitting / reflecting sheet has a pattern of a transmitting portion and a reflecting portion in each divided area, so that the wiring board and the light are bent when the optical sheet is bent. If the distance to the transmission / reflection sheet changes, the in-plane uniformity of the luminance may be reduced. On the other hand, according to the present embodiment, since the first spacer 330 includes the wall portion 332 including the first portion 333 and the second portion 334 intersecting with the first portion 333, The contact area with the first optical sheet 320 can be increased as compared to a columnar spacer. Thereby, the bending of the first optical sheet 320 can be suppressed. Further, since the first spacer 330 can suppress the deflection of the first optical sheet 320 which is a light transmitting / reflecting sheet, the distance between the wiring substrate 41 and the first optical sheet 320 is maintained at a predetermined distance. The in-plane uniformity of the luminance can be improved.

  The applications of the image display devices 10 and 300 and the surface light source devices 20 and 310 according to the first embodiment and the second embodiment are not particularly limited, but for example, television applications, vehicle applications and advertisement media applications such as billboards. It can be used. Among these, the image display devices 10 and 300 and the surface light source devices 20 and 310 can endure a vibration test, and thus can be suitably used for in-vehicle applications.

  EXAMPLES The present invention will be described by way of examples to describe the present invention in detail, but the present invention is not limited to these descriptions.

<< Example A and Comparative Example A >>
Example A1
First, an LED mounting substrate was produced. Specifically, a 35 μm thick copper layer for wiring was laminated on one side of a polyethylene naphthalate film having a length of 111 mm × width 293 mm and a thickness of 50 μm. Thereafter, the copper layer for wiring was etched to form a copper wiring portion. After forming the copper wiring portion, an insulating protective film having a thickness of 50 μm was formed by screen printing to obtain a flexible wiring substrate. After obtaining the flexible wiring board, a total of 60 LED elements, 5 vertical × 12 horizontal, were mounted on the copper wiring portion of the flexible wiring board via a solder layer by a reflow method, to obtain an LED mounting board.

  Moreover, the light transmission reflective sheet was produced. The light transmitting / reflecting sheet was manufactured 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 a total of 60 divided areas consisting of 5 vertical parts × 12 horizontal parts each consisting of a transmitting part and a reflecting part was obtained. In the light transmitting / reflecting sheet, the size of each divided area was 22 mm long × 24.2 mm wide, and the aperture ratio gradually increased from the center to the outer edge of each divided area.

  In addition, a first spacer was produced. The first spacer was in the form of a lattice and was produced by injection molding using a polycarbonate resin. The first spacer has an opening as a light passage region arranged in a matrix of 5 longitudinal × 12 transversely penetrating in the height direction of the first spacer having a length of 20 mm × 22.4 mm, and a length of 111 mm × A rectangular frame having a width of 290 mm, a width of 2 mm, and a height of 2 mm, and a wall having a partition of 2 mm in width and a height of 2 mm integrally formed with the frame. It was something that The wall was to surround all the openings. Further, the partition portion extends in a first direction extending in a first direction along the lateral direction of the first spacer, and extends in a second direction along the longitudinal direction of the first spacer, and It consisted of the crossing second part.

  In addition, a second spacer was made. The second spacer was produced by injection molding using a polycarbonate resin. The second spacer penetrates in the height direction of the second spacer with a size of 113 mm long × 306 mm wide inside the frame with a frame of 117 mm long × 310 mm wide and 2 mm wide and 5 mm high. Provided with two openings.

  And the produced LED mounting substrate was arrange | positioned so that a LED element might become upper side in the aluminum-made housing main body which has an accommodation space of size 117 mm long x 310 mm wide x 7 mm in height. Next, the first spacer prepared above is fixed to the surface of the flexible wiring substrate in the LED mounting substrate via a double-sided tape (product name "No. 5000 NS", manufactured by Nitto Denko Corporation), and further fixed on the first spacer The light transmitting and reflecting sheet prepared above was fixed via a double-sided tape (product name "No. 5000 NS" manufactured by Nitto Denko Corporation). The first spacer is disposed such that the light from each LED element passes through the opening of the first spacer, and the light transmitting / reflecting sheet has a boundary between the divided regions of the first spacer. It was arranged to be at the position of the partition. Further, the second spacer produced above is disposed between the housing body and the LED mounting substrate and the first spacer, and the second spacer is a double-sided tape (product name "No. 5000 NS") on the bottom surface of the housing body. ", Fixed through Nitto Denko Co., Ltd.). Furthermore, a light diffusion sheet of 117 mm long × 310 mm wide and 1.5 mm thick was disposed on the second spacer. Finally, a frame-like lid having an opening with a size of 110 mm long and 303 mm wide was fitted to the case body to obtain an LED surface light source device. The distance from the surface of the flexible wiring board to the light transmitting and reflecting sheet is 2 mm, the distance from the surface of the flexible wiring board to the light diffusing sheet is 4.8 mm, and the light transmitting and reflecting sheet and the light diffusing sheet The distance between the two was 2.3 mm.

Example A2
In Example A2, a first spacer and an LED surface light source device were obtained in the same manner as in Example A1, except that a soft vinyl chloride resin was used instead of a polycarbonate resin and a first spacer was produced. .

Comparative Example A1
In Comparative Example A1, an LED surface light source device was obtained in the same manner as in Example A1, except that a plurality of columnar first spacers were used instead of the lattice-shaped first spacers. The first spacer used in Comparative Example A1 was a columnar member having a diameter of 5 mm and a height of 2 mm made of polycarbonate resin, and one spacer was disposed between each of the LED elements. The columnar first spacer was fixed to the flexible wiring base and the light reflective sheet through a double-sided tape (product name “No. 5000 NS” manufactured by Nitto Denko Corporation).

Comparative Example A2
Comparative Example A2 is the same as Example A1, except that instead of the lattice-like first spacer, a frame-like first spacer having one opening without a partition is used. An LED surface light source device was obtained. The first spacer used in Comparative Example A2 is a frame made of polycarbonate resin and having a size of 111 mm × 290 mm, a width of 2 mm, and a height of 2 mm, and one frame of 107 mm × 286 mm inside the frame portion. And an opening. The frame-shaped first spacer was fixed to the flexible wiring base and the light reflecting and transmitting sheet via a double-sided tape (product name "No. 5000 NS" manufactured by Nitto Denko Corporation).

<Deflection evaluation>
In the LED surface light source devices according to Examples A1 and A2 and Comparative Examples A1 and A2, it was visually evaluated whether or not deflection occurred in the light transmitting / reflecting sheet. In addition, bending shall be confirmed by the light transmission reflective sheet before the vibration test mentioned later.
○: No deflection was observed in the light transmitting / reflecting sheet.
X: Deflection was confirmed in the light transmission reflective sheet.

<In-plane uniformity evaluation of luminance>
In the LED surface light source devices according to Examples A1 and A2 and Comparative Examples A1 and A2, the vibration test is performed, and the luminance distribution of the light emitting surface (the surface of the light diffusion sheet) of the LED surface light source device is measured before and after the vibration test. While measuring and evaluating the in-plane uniformity of brightness | luminance, the change rate of the in-plane uniformity before and behind a vibration test was calculated | required, and it was evaluated how much in-plane uniformity fell before and after a vibration test.

  Vibration test, the vibration table side of the housing in the short side direction of the LED surface light source device on the vibration table of single axis electrodynamic vibration test device (product name "EM 2605S / H10", manufactured by IMV Corporation) The LED surface light source device is fixed with the LED surface light source device standing upright, and vibrated for 1 hour in each direction of three axial directions (X direction, Y direction, Z direction) orthogonal to each other under the following conditions It went by. The vibration conditions were a sweep rate of 1 oct / min, a frequency of 10 Hz to 30 Hz with an amplitude of ± 0.75 mm, and a frequency of 30 Hz to 500 Hz, an acceleration of 3 G.

  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 current of 180 mA is applied per LED element to turn on the LED elements. In two places, it measured using a two-dimensional color luminometer (product name "CA-2000", Konica Minolta Co., Ltd. make).

The in-plane uniformity of luminance is based on the maximum luminance (Lv _max ) and the minimum luminance (Lv _min ) in the luminance distribution within the evaluation range, with 22.4 mm long and 146.4 mm wide in the central area in the measurement area. Te, by determining the ratio of the minimum luminance to the maximum luminance _{(Lv max) (Lv min)} (Lv min / Lv max), were quantified.

Also, using the in-plane uniformity of luminance before vibration test and the in-plane uniformity of luminance after vibration test determined above, the rate of change of in-plane uniformity of luminance before and after vibration test is determined, before and after vibration test It was evaluated how much the in-plane uniformity of the luminance decreased. Evaluation criteria were as follows.
Good: The change rate of the in-plane uniformity of the luminance before and after the vibration test was within 10%.
X: The change rate of the in-plane uniformity of the luminance before and after the vibration test exceeded 10%.
The rate of change in in-plane uniformity of luminance before and after the vibration test is the difference between the in-plane uniformity of luminance before the vibration test and the in-plane uniformity of luminance after the vibration test (the in-plane uniformity of luminance before the vibration test In-plane uniformity of luminance after vibration test).

<Appearance evaluation>
In the LED surface light source device according to Examples A1 and A2 and Comparative Examples A1 and A2, the appearance of the first spacer after the vibration test was visually observed and evaluated. Evaluation results were based on the following criteria.
:: No damage such as cracking or breakage was found in the first spacer.
X: In the first spacer, damage such as cracking or breakage was confirmed.

<Glass transition temperature measurement>
The glass transition temperature of the wall portion of the first spacer according to Example A1 and A2 was measured. The glass transition temperature was obtained by scraping 10 mg of the wall portion to obtain a sample, and was measured using a differential scanning calorimeter (DSC) at a temperature rising rate of 5 ° C./min. The glass transition temperature was an arithmetic mean value of values measured three times.

<Mold shrinkage ratio measurement>
The molding shrinkage rate of the wall portion of the first spacer according to Example A1 and A2 was measured under the following conditions. The measurement of the molding shrinkage of the wall is carried out in accordance with JIS K 6911: 1995, and in the measurement of the molding shrinkage of the wall, the resin constituting the wall is melted by heating the wall. The molded product obtained by pouring the resin into a mold and solidifying was used.

<Heat resistance test>
With respect to the first spacers according to Examples A1 and A2, heat resistance tests in which the first spacers were left for 1000 hours in an environment of 85 ° C. were respectively subjected to a heat resistance test to evaluate the appearance of the first spacers after the test. Evaluation criteria were as follows.
○: The shape of the first spacer was almost unchanged before and after the heat resistance test.
Δ: The shape of the first spacer was slightly changed before and after the heat resistance test.
X: The shape of the first spacer was significantly changed before and after the heat resistance test.

The results are shown in Tables 1 and 2 below.

  The following describes the results. In Comparative Example A1, since the first spacer was columnar, deflection was confirmed in the light transmitting / reflecting sheet. Moreover, in the comparative example A1, the in-plane uniformity of the brightness | luminance before a vibration test was low. It is considered that this is because the light transmitting and reflecting sheet was bent. Furthermore, in Comparative Example A1, the in-plane uniformity of the luminance after the vibration test was clearly reduced as compared to the in-plane uniformity of the luminance before the vibration test. This is considered to be because the first spacer is columnar, so that the rigidity is low, and the light transmission / reflection sheet has been displaced with respect to the LED element in the vibration test.

  In Comparative Example A2, since the first spacer was in the form of a frame having no partition part, deflection was confirmed in the light transmitting / reflecting sheet. Further, in Comparative Example A2, the in-plane uniformity of the luminance before the vibration test was low. It is considered that this is because the light transmitting and reflecting sheet was bent. Furthermore, in Comparative Example A2, the in-plane uniformity after the vibration test was clearly reduced as compared to the in-plane uniformity before the vibration test. This is because the first spacer was in the form of a frame having no partition, so the rigidity is low, and it is considered that the light transmitting / reflecting sheet has been displaced with respect to the LED element by the vibration test. Be

  On the other hand, in Examples A1 and A2, since the first spacer was formed of the wall portion having the frame portion and the partition portion, no deflection was observed in the light transmitting / reflecting sheet. Moreover, in Example A1, the in-plane uniformity of the brightness | luminance before a vibration test was high. This is considered to be because the light transmitting / reflecting sheet was not bent. Furthermore, in Example A1, the decrease in in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed more than in Comparative Examples A1 and A2. This is because the first spacer is composed of the wall portion having the frame portion and the partition portion, so the rigidity is high, and the positional deviation of the light transmitting / reflecting sheet with respect to the LED element almost does not occur even by the vibration test. It is considered to be a thing.

<< Example B and Comparative Example B >>
Example B1
First, an LED mounting substrate was produced. Specifically, a 35 μm thick copper layer for wiring was laminated on one side of a polyethylene naphthalate film having a length of 111 mm × width 293 mm and a thickness of 50 μm. Thereafter, the copper layer for wiring was etched to form a copper wiring portion. After forming the copper wiring portion, an insulating protective film having a thickness of 50 μm was formed by screen printing to obtain a flexible wiring substrate. After obtaining the flexible wiring board, a total of 60 LED elements, 5 vertical × 12 horizontal, were mounted on the copper wiring portion of the flexible wiring board via a solder layer by a reflow method, to obtain an LED mounting board.

  Moreover, the light transmission reflective sheet was produced. The light transmitting / reflecting sheet was manufactured 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. Here, among the openings, at positions corresponding to the projections provided on the first spacer, the openings having a size that allows the projections to enter are formed. As a result, a light transmitting / reflecting sheet having a total of 60 divided areas consisting of 5 vertical parts × 12 horizontal parts each consisting of a transmitting part and a reflecting part was obtained. In the light transmitting / reflecting sheet, the size of each divided area was 22 mm long × 24.2 mm wide, and the aperture ratio gradually increased from the center to the outer edge of each divided area.

  In addition, a first spacer was produced. The first spacer was in the form of a lattice and was produced by injection molding using a polycarbonate resin. The first spacer has a rectangular frame with a size of 111 mm long × 290 mm wide, 2 mm wide and 2 mm high, and a height of the first spacer 20 mm long × 22.4 mm wide inside the frame. The openings as light passing areas arranged in a matrix of 5 columns by 12 columns extending longitudinally and a width 2 mm and a height 2 mm provided between the openings and integrally provided with the frame And a protrusion having a height of 0.2 mm provided integrally with the partition at four locations of the partition and the surface of the partition disposed on the light transmitting / reflecting sheet side. Further, the partition portion extends in a first direction extending in a first direction along the lateral direction of the first spacer, and extends in a second direction along the longitudinal direction of the first spacer, and It consisted of the crossing second part.

  In addition, a second spacer was made. The second spacer was produced by injection molding using a polycarbonate resin. The second spacer penetrates in the height direction of the second spacer with a size of 113 mm long × 306 mm wide inside the frame with a frame of 117 mm long × 310 mm wide and 2 mm wide and 5 mm high. Provided with two openings.

  And the produced LED mounting substrate was arrange | positioned so that a LED element might become upper side in the aluminum-made housing main body which has an accommodation space of size 117 mm long x 310 mm wide x 7 mm in height. Then, the first spacer produced above was fixed to the surface of the flexible wiring board in the LED mounting board via a double-sided tape (product name “No. 5000 NS” manufactured by Nitto Denko Corporation). The first spacer had a convex portion located on the side opposite to the flexible wiring substrate side, and was arranged such that light from each LED element could pass through the opening of the first spacer. After arranging the first spacer, the light transmitting and reflecting sheet prepared above was fixed on the first spacer via a double-sided tape (product name “No. 5000 NS”, manufactured by Nitto Denko Corporation). Here, when arranging the light transmitting / reflecting sheet, while aligning the light transmitting / reflecting sheet with the first spacer so that the convex portions of the first spacer enter the opening of the light transmitting / reflecting sheet, A light transmitting and reflecting sheet was disposed. In addition, the boundary part between the division area | regions in a light transmissive reflection sheet was the position of the partition part of a 1st spacer. Next, the second spacer produced above is disposed between the housing body and the LED mounting substrate and the first spacer, and the second spacer is a double-sided tape (product name "No. 5000 NS") on the bottom surface of the housing body. ", Fixed through Nitto Denko Co., Ltd.). Furthermore, a light diffusion sheet of 117 mm long × 310 mm wide and 1.5 mm thick was disposed on the second spacer. Finally, a lid having an opening having a size of 110 mm long and 303 mm wide was fitted to the case body to obtain a surface light source device. The distance from the surface of the flexible wiring board to the light transmitting / reflecting sheet is 2 mm, the distance from the surface of the flexible wiring board to the light diffusing sheet is 4.8 mm, and the distance between the light transmitting / reflecting sheet and the light diffusing sheet is The distance of was 2.3 mm.

Comparative Example B1
In Comparative Example B1, a surface light source device was obtained in the same manner as Example B1, except that a plurality of columnar first spacers were used instead of the lattice-shaped first spacers. The first spacer used in Comparative Example B1 was a pillar made of polycarbonate resin and having a diameter of 5 mm and a height of 2 mm, and was disposed one by one between the respective LED elements. The columnar first spacer used in Comparative Example B1 was fixed to the flexible wiring base and the light reflecting and transmitting sheet via a double-sided tape (product name “No. 5000 NS” manufactured by Nitto Denko Corporation). Moreover, the columnar first spacer used in Comparative Example B1 had no convex portion on the surface on the light transmitting and reflecting sheet side.

Comparative Example B2
In Comparative Example B2, a surface light source device was obtained in the same manner as Example B1, except that a frame-shaped first spacer having no partition was used instead of the lattice-shaped first spacer. . The first spacer used in Comparative Example B2 is a frame made of polycarbonate resin and having a length of 111 mm × width mm, a width of 2 mm, and a height of 2 mm, and one frame of 107 mm length × 286 mm width inside the frame portion. And an opening. The frame-shaped first spacer used in Comparative Example B2 was fixed to the flexible wiring base and the light reflecting and transmitting sheet via a double-sided tape (product name "No. 5000 NS" manufactured by Nitto Denko Corporation). . Moreover, the frame-shaped 1st spacer used by Comparative Example B2 was a thing in which the convex part was not provided in the surface at the side of a light transmissive reflection sheet.

<In-plane uniformity evaluation of luminance>
In the surface light source devices according to Example B1 and Comparative Examples B1 and B2, the vibration test is performed, and the luminance distribution of the light emitting surface (the surface of the light diffusion sheet) of the surface light source device is measured before and after the vibration test. The in-plane uniformity was evaluated, and the rate of change in the in-plane uniformity before and after the vibration test was determined to evaluate how much the in-plane uniformity decreased before and after the vibration test. The conditions for the vibration test, the measurement conditions for the luminance distribution, and the evaluation criteria of how much the in-plane uniformity decreased before and after the vibration test were the same conditions and evaluation criteria as in Example A.

<Deflection evaluation>
In the surface light source devices according to Example B1 and Comparative Examples B1 and B2, it was visually evaluated whether or not deflection occurred in the light transmitting / reflecting sheet. In addition, bending shall be confirmed by the light transmission reflective sheet before the vibration test mentioned later.
○: No deflection was observed in the light transmitting / reflecting sheet.
X: Deflection was confirmed in the light transmission reflective sheet.

<Appearance evaluation>
In the surface light source device according to Example B1 and Comparative Examples B1 and B2, the appearance of the first spacer after the vibration test was visually observed and evaluated. Evaluation results were based on the following criteria.
:: No damage such as cracking or breakage was found in the first spacer.
X: In the first spacer, damage such as cracking or breakage was confirmed.

The results are shown in Table 3 below.

  The following describes the results. In Comparative Example B1, the in-plane uniformity of the luminance after the vibration test was clearly reduced compared to the in-plane uniformity of the luminance before the vibration test. This is because the first spacer was not provided in the convex portion, and the first spacer was columnar and its rigidity was low, so that the light transmission reflection sheet is positioned with respect to the LED element by the vibration test. It is thought that it has caused a gap. Further, in Comparative Example B1, since the first spacer was columnar, deflection was confirmed in the light transmitting / reflecting sheet. Moreover, in the comparative example B1, the in-plane uniformity of the brightness | luminance before a vibration test was low. It is considered that this is because the accuracy of the alignment of the light transmission reflective sheet with the LED element is low and / or the light transmission reflective sheet is bent.

  In Comparative Example B2, the in-plane uniformity after the vibration test was clearly reduced compared to the in-plane uniformity before the vibration test. This is because the first spacer was not provided in the convex portion, and the first spacer was in the form of a frame having no partition, and the rigidity was low. It is considered that the light transmitting / reflecting sheet has been displaced. In addition, since the first spacer was in the form of a frame having no partition, bending was observed in the light transmitting and reflecting sheet. Moreover, in the comparative example B2, the in-plane uniformity of the brightness | luminance before a vibration test was low. It is considered that this is because the accuracy of the alignment of the light transmission reflective sheet with the LED element is low and / or the light transmission reflective sheet is bent.

  On the other hand, in Example B1, the decrease in in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed more than in Comparative Examples B1 and B2. This is because the first spacer is provided with a projection, and is inserted into the opening of the light transmitting / reflecting sheet, and the first spacer has a frame and a partition and has high rigidity, Also in the vibration test, it is considered that the positional deviation of the light transmitting / reflecting sheet with respect to the LED element hardly occurred. In Example B1, since the first spacer was composed of the frame portion and the partition portion, no deflection was observed in the light transmitting / reflecting sheet. Further, in Example B1, the in-plane uniformity of the luminance before the vibration test was high. It is considered that this is because the first spacer was provided with the convex portion, so that the alignment accuracy of the light transmitting and reflecting sheet with respect to the LED element was high, and / or the light transmitting and reflecting sheet was not bent. .

10, 300 ... image display device 20, 310 ... surface light source device 40 ... LED mounting substrate 41 ... wiring substrate 42 ... LED element 50, 320 ... first optical sheet 50A ... outer peripheral surface 51, 321 ... partition area 51A, 321A ... Central part 51B, 321B ... outer edge part 52, 322 ... transmission part 53, 323 ... reflection part 60, 140, 150, 160, 170, 180, 190, 200, 210, 220, 330 ... first spacer 60A ... outer peripheral surface 61, 141, 151, 161, 171, 181 ... openings 62, 142, 152, 162, 172, 182, 192, 202, 212, 222, 222, 332 ... walls 63, 143, 153, 163, 173, 183, 193, 203, 213, 223, 333 ... the first portion 64, 144, 154, 164, 174, 184, 194, 20 , 214, 224, 334 second part 65, 336 frame part 66, 337 partition part 70 second optical sheet 80 second spacer 335 convex part DR1 first direction DR2 second Direction of

Claims (10)

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 to face the plurality of LED elements;
A second optical sheet disposed on the light emitting side of the first optical sheet,
And a first spacer disposed between the LED mounting substrate and the first optical sheet to separate the first optical sheet from the LED mounting substrate.
The first optical sheet and the second optical sheet are in close contact with each other ,
The first optical sheet includes a plurality of divided regions in plan view, and each of the plurality of divided regions includes a plurality of transmitting portions transmitting a portion of light, and a plurality of reflections reflecting a portion of light And an aperture ratio, which is an area ratio of the transmission part in each of the divided areas, is gradually increased from a central part of the divided area toward an outer edge of the divided area.
The second optical sheet is a light diffusion sheet,
The first spacer is fixed to the wiring substrate and the first optical sheet,
The first spacer has a first portion extending in a first direction, and a second portion extending in a second direction different from the first direction and intersecting the first portion. A wall including a partition, and a light passing area that is present in an area other than the wall and allows light to pass through;
The first spacer is disposed such that the partition is located at a boundary between the divided regions of the first optical sheet.
The light passage area in the first spacer is two or more openings penetrating in the height direction of the first spacer, and the openings are partitioned by the partition portion of the wall portion,
The side surface facing the opening in the wall portion of the first spacer is inclined such that the opening diameter of the opening increases from the LED mounting substrate toward the first optical sheet. ,
Wherein the ratio of the first width of the upper surface is the surface of the first optical sheet side to the width of the bottom surface is a surface of the LED mounting substrate side in the spacer Ri der 0.95 or less,
The surface light source device, wherein a thickness of the wall portion in the first spacer is 0.2 mm or more and 10 mm or less . 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 to face the plurality of LED elements;
A second optical sheet disposed on the light emitting side of the first optical sheet,
And a first spacer disposed between the LED mounting substrate and the first optical sheet, fixed to the wiring substrate, and separating the first optical sheet from the LED mounting substrate.
The first optical sheet and the second optical sheet are in close contact with each other ,
The first optical sheet includes a plurality of divided regions in plan view, and each of the plurality of divided regions includes a plurality of transmitting portions transmitting a portion of light, and a plurality of reflections reflecting a portion of light And an aperture ratio, which is an area ratio of the transmission part in each of the divided areas, is gradually increased from a central part of the divided area toward an outer edge of the divided area.
The first optical sheet has a hole in a surface on the first spacer side,
The second optical sheet is a light diffusion sheet,
The first spacer has a first portion extending in a first direction, and a second portion extending in a second direction different from the first direction and intersecting the first portion. A wall provided with a partition, a light passing area existing in an area other than the wall and passing light, and a surface of the wall on the first optical sheet side and in the hole And one or more convex parts that enter
The first spacer is disposed such that the partition is located at a boundary between the divided regions of the first optical sheet.
The light passage area in the first spacer is two or more openings penetrating in the height direction of the first spacer, and the openings are partitioned by the partition portion of the wall portion,
The side surface facing the opening in the wall portion of the first spacer is inclined such that the opening diameter of the opening increases from the LED mounting substrate toward the first optical sheet. ,
Wherein the ratio of the first width of the upper surface is the surface of the first optical sheet side to the width of the bottom surface is a surface of the LED mounting substrate side in the spacer Ri der 0.95 or less,
The surface light source device, wherein a thickness of the wall portion in the first spacer is 0.2 mm or more and 10 mm or less . The surface light source device of Claim 1 or 2 whose glass transition temperature of the said wall part exceeds 85 degreeC . The surface light source device according to any one of claims 1 to 3, wherein a molding shrinkage rate of the wall portion is less than 1.0%. It said wall portion, and a polycarbonate resin, a surface light source device according to claim 1 or 2. The surface light source device according to any one of claims 1 to 5, wherein the wall portion has a lattice shape or a honeycomb shape. The transmissive portion of the first optical sheet, an opening portion penetrating in the thickness direction of the first optical sheet, at least one of the openings functions as the hole, according to claim 2 Surface light source device. The surface light source device according to any one of claims 1 to 7 , wherein a thickness of the first optical sheet is 25 μm or more and 1 mm or less. A flexible wiring board comprising: a resin film having flexibility; and a metal wiring portion provided on the first optical sheet side with respect to the resin film and electrically connected to the LED element. The surface light source device according to any one of claims 1 to 8 . A surface light source device according to any one of claims 1 to 9 ,
A display panel disposed closer to the viewer than the surface light source device;
An image display apparatus comprising:

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