JP2019040874A - Spacer, surface light source device and image display device - Google Patents

Abstract

To provide a spacer that can suppress deflection of an optical sheet and that, even in a vibration test, can suppress position shift of the optical sheet relative to an opposite member and is hardly damaged, a surface light source device comprising the spacer, and an image display device.SOLUTION: In an image display device 10, a first spacer 60 is used in a surface light source device 20 comprising a first optical sheet 50 and an LED mounting substrate 40 opposite to the first optical sheet 50, and is positioned between the first optical sheet 50 and the LED mounting substrate 40 to separate the first optical sheet 50 from the LED mounting substrate 40. The first spacer 60 comprises a wall part 62 that has a first part extending to a first direction and a second part extending to a second direction different from the first direction and intersecting with the first part, and openings 61 that are provided in areas other than the wall part 62 and serve as light transmission areas capable of transmitting light.SELECTED DRAWING: Figure 1

Description

Reference to related applications

  The present application is Japanese Patent Application No. 2006-253328 (application date: December 27, 2016), Japanese Patent Application No. 2006-253332 (application date: December 27, 2016) and Japanese Patent Application No. 2017-104442 (prior application) which are prior Japanese applications. (The filing date: May 26, 2017), the entire contents of which are 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 In recent years, LED image display devices that have rapidly spread are generally provided with a display screen such as a liquid crystal display panel and an LED surface light source device that illuminates the display screen from the back side. Currently, edge-light type LED surface light source devices are often used in LED image display devices, but from the viewpoint of brightness, the use of direct type LED surface light source devices has been studied.

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

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

  However, when columnar spacers are used, the optical sheet may be bent between the spacers. 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, which may reduce the in-plane luminance uniformity.

  Currently, the use of LED image display devices for vehicles such as automobiles and advertising media is being studied. In a vehicle, since vibration is generated from the vehicle, the vibration of the vehicle may be transmitted to the LED image display device mounted on the vehicle. Further, in the advertisement medium, for example, when LED image display is used for a signboard such as a station platform or a mobile signboard having wheels or the like, the vibration of a train or the like and the vibration when moving are the LED image display device. It may be transmitted to.

  However, in conventional LED surface light source devices, no measures are taken against vibration and impact. For this reason, when a vibration test is performed on the LED surface light source device including 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 optically applied to the LED element. There is a possibility that the position of the sheet is shifted, that is, a so-called positional shift occurs. In particular, when a light-transmitting / reflecting sheet is used as the optical sheet, if the light-transmitting / reflecting sheet is misaligned, the position of the opening pattern with respect to the LED element is misaligned, which may reduce the in-plane luminance uniformity. . In addition, when a vibration test is performed, the columnar spacer may be damaged.

  In addition, when a light transmission / reflection sheet is used as the optical sheet, the light immediately above the LED element is reflected and diffused to the surroundings with the light transmission / reflection sheet being separated from the LED mounting board on which the LED element is mounted. In order to improve the in-plane uniformity of brightness by emitting light from the surrounding openings, it is important to align the LED element and the opening pattern. However, no measures have been taken regarding the alignment with the LED element. There is no current situation.

  The present invention has been made to solve the above problems. That is, the optical sheet can be prevented from being bent, and even when a vibration test is performed, the optical sheet can be prevented from being displaced with respect to the opposing member, and the spacer is not easily damaged. An object is to provide an apparatus. In addition, it is possible to provide a surface light source device that facilitates the alignment of the first optical sheet with respect to the LED element and can suppress the displacement of the first optical sheet with respect to the LED element, and an image display device including the surface light source device. Objective.

  According to one aspect of the present invention, the facing member is used in a surface light source device including an optical sheet and a facing member facing the optical sheet, and is disposed between the optical sheet and the facing member. A first portion extending in a first direction, and a spacer extending in a second direction different from the first direction and intersecting the first portion. There is provided a spacer comprising: a wall portion including two portions; and a light passage region that exists in a region other than the wall portion and allows light to pass therethrough.

  In the spacer, the light passage 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.

  The said spacer WHEREIN: The side surface which faces the said opening part of the said wall part may incline so that the opening diameter of the said opening part may become large toward the said optical sheet from the said opposing member.

  In the spacer, the glass transition temperature of the wall portion may exceed 85 ° C.

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

  In the spacer, the wall portion may be made of a 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, the first optical sheet, a facing member facing the first optical sheet, and the first optical sheet and the facing member are disposed between the facing member and the facing member. A first spacer that separates the first optical sheet with respect to the first spacer, the first spacer being fixed to the opposing member and the first optical sheet, and the first spacer being A surface light source device that is the spacer is provided.

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

  In the surface light source device, the first optical sheet includes a plurality of divided areas in a plan view, and each of the divided areas transmits a part of light and a part of the light. A plurality of reflection portions that reflect the light, and an aperture ratio that is an area ratio of the transmission portion in each partition region is gradually increased from a central portion of the partition region toward an outer edge portion of the partition region. Good.

  According to another aspect of the present invention, a wiring board, an LED mounting board including a plurality of LED elements mounted on one surface of the wiring board, and a first board disposed to face the plurality of LED elements. 1 optical sheet, a first spacer that is disposed between the LED mounting substrate and the first optical sheet, is fixed to the wiring substrate, and separates the first optical sheet from the LED mounting substrate. The first optical sheet has a hole in the first spacer side surface, and the first spacer extends in a first direction, and the first 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 passage region that is present in a region other than the wall portion and allows light to pass therethrough. And the first optical sheet side of 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 passage region is two or more openings penetrating in a height direction of the first spacer, and the openings are formed by the first portion and the second portion of the wall portion. The space may be partitioned.

  In the surface light source device, the first optical sheet includes a plurality of divided areas in a plan view, and each of the divided areas transmits a part of light and a part of the light. A plurality of reflection portions that reflect the light, and an aperture ratio that is an area ratio of the transmission portion in each partition region is gradually increased from a central portion of the partition region toward an outer edge portion of the partition region. Good.

  In the surface light source device, the transmission portion of the first optical sheet is an opening that penetrates 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 not less than 25 μm and not more than 1 mm.

  In the surface light source device, the wiring substrate includes a flexible resin film, and a metal wiring portion that is provided closer to the first optical sheet than the resin film and is electrically connected to the LED element. A flexible wiring board may be provided.

  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 to surround the second optical sheet. And a frame-shaped second spacer that separates 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 above 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 provide a spacer that can suppress the deflection of the optical sheet, suppress the displacement of the optical sheet with respect to the facing member, and is not easily damaged even when a vibration test is performed. Can do. Moreover, according to the other aspect of this invention, a surface light source device and an image display apparatus provided with such a spacer can be provided. Moreover, according to the other aspect of this invention, while aligning the 1st optical sheet with respect to an LED element easily, the surface light source device which can suppress the position shift of the 1st optical sheet with respect to an LED element, and this An image display device provided can be provided.

FIG. 1 is an exploded perspective view of the image display apparatus according to the first embodiment. FIG. 2 is a schematic configuration diagram of the image display apparatus 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 positional relationship between 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. FIG. 11A and FIG. 11B are plan views of other first spacers according to the first embodiment. FIGS. 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 a part of another partition unit according to the first embodiment. FIG. 14A and FIG. 14B are partial cross-sectional views of other partition portions 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 apparatus according to the second embodiment. FIG. 19 is a schematic configuration diagram of an image display apparatus 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 this specification, “LED” means a light emitting diode. Further, terms such as “sheet”, “film”, and “plate” are not distinguished from each other based only on the difference in designation. Therefore, for example, “sheet” is used to include a member called a film or a plate. FIG. 1 is an exploded perspective view of an image display device according to the present embodiment, FIG. 2 is a schematic configuration diagram of the image display device according to the present embodiment, and FIG. 3 is a part of the surface light source device according to the present embodiment. FIG. 4 is a plan view of the first optical sheet shown in FIG. 1, FIG. 5 is a plan view of 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 between 1 and a 1st spacer. 7 to 12 are plan views of other first spacers according to the present embodiment, FIGS. 13 and 14 are partial sectional views of other partition portions according to the present embodiment, and FIG. FIG. 16 is a perspective view of an intersection of a first portion and a second portion of a first spacer, and FIG. 16 is a plan view showing an arrangement 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 device 10 shown in FIGS. 1 and 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 exit side, a polarizing plate 121 and a polarizing plate 122. And a liquid crystal cell 123 disposed between them. As the polarizing plates 121 and 122 and the liquid crystal cell 123, known polarizing plates and liquid crystal cells can be used.

<<< Surface 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. The spacer 80 is provided. In addition, the surface light source device 20 includes a lens sheet 90 and a reflective polarization separation sheet 100 laminated on the second optical sheet 70. In addition, the surface light source device 20 should just be equipped with the LED mounting board 40, the 1st optical sheet 50, and the 1st spacer 60, and the housing | casing 30, the 2nd optical sheet 70, the 2nd 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 a facing member that faces 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. Note that the facing member may not be the LED mounting substrate as long as it is a member facing the optical sheet.

  Since the in-vehicle surface light source device is arranged in a very narrow space in the vehicle, it is desired to make the surface light source device 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 reducing the thickness. The total thickness of the “surface light source device” means the distance from the outer bottom surface 30 </ b> C of the housing 30 shown in FIG. 2 to the surface 100 </ b> A of the reflective polarization separation sheet 100.

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

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

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

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

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

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

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

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

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

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

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

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

  The thickness of the resin film 43 is not particularly limited, but is generally 10 μm or more and 500 μm or less from the viewpoint of not being a bottleneck as a heat dissipation path, having heat resistance and insulation, and a balance of manufacturing costs. It is preferable that Moreover, it is preferable that it is the said thickness range also from a viewpoint of maintaining productivity favorable when manufacturing by a roll-to-roll system. The thickness of the resin film 43 is obtained by photographing the cross section of the resin film 43 using a scanning electron microscope (SEM), measuring the thickness of any 10 positions of the resin film 43 in the image of the cross section, and calculating the average value. It shall be obtained 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 part)
The metal wiring portion 44 is provided closer to the LED element 42 than the resin film 43 and is electrically connected to the LED element 42. The metal wiring part 44 can be formed by patterning a metal foil or the like.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The first optical sheet 50 is disposed so as 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 board 41.

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

  The thickness of the first optical sheet 50 is preferably 25 μm or more and 1 mm or less. If the thickness of the light transmitting / reflecting sheet is less than 25 μm, the desired reflectance may not be obtained, and if it exceeds 1 mm, the 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). It can be obtained by measuring the thickness of any 10 locations of the optical sheet 50 and calculating the average value. As shown in FIG. 4, the first optical sheet 50 includes a partitioned area 51 that is divided into a plurality of parts in plan view.

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

  As shown in FIG. 4, each partition region 51 includes a plurality of transmission parts 52 that transmit a part of the light from the LED element 42, and a plurality of reflection parts 53 that reflect a part of the light from the LED element 42. It consists of The transmission part 52 and the reflection part 53 are configured in a predetermined pattern. The portion corresponding to the LED element in each partition region is the portion where the most light is incident. Therefore, when light is transmitted from this portion, the brightness of this portion becomes higher than the brightness of the other portions of the partition region. There is a risk that the in-plane uniformity of the luminance is lowered. For this reason, it is preferable that a portion corresponding to the LED element 42 in each partition region 51 is configured by the reflection portion 53. In addition, in FIG. 4, the transmission part 52 is represented in white formally, and the reflection part 53 is represented in gray. Moreover, although the pattern of the transmission part 52 and the reflection part 53 in each division area 51 is the same, it does not necessarily need to be the same and a pattern which changes with division areas may be sufficient. The transmission part 52 and the reflection part 53 may have a grid pattern.

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

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

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

<Transmission part>
The transmissive portion 52 is a region where the reflective layer 55 is not formed on any of both surfaces of the resin film 54 and is a region where both surfaces of the resin film 54 in FIG. 3 are exposed. As the resin film 54, a conventionally known transparent film is preferably used, and the total light transmittance is preferably 85% or more. The total light transmittance 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 average value of values obtained by measuring three times.

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

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

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

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

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

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

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

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

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

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

  The first spacer includes a first portion that extends in a first direction, and a wall portion that includes a second portion that extends in a second direction different from the first direction and intersects the first portion. And a light passage region that exists in a region other than the wall and allows light to pass therethrough. In this specification, “extending in the first direction” means that it is sufficient that the first portion extends in the first direction when the first portion is viewed globally. You don't have to. Similarly, “extending in the second direction” means that it is sufficient that the second portion extends in the second direction when the second portion is viewed globally, and the second portion extends along the second direction. You don't have to. As shown in FIG. 5, the first spacer 60 divides the opening 61 as two or more light transmissive regions penetrating in the height direction of the first spacer 60 and the opening 61, and at least And a wall 62 surrounding the periphery of one opening 61.

<Opening>
The opening 61 is for allowing light from each LED element 42 to pass through. Although the number of openings 61 is not particularly limited, in FIG. 5, 4 vertical openings × 6 horizontal openings = 24 openings corresponding to the number of LED elements 42 (vertical 4 × horizontal 6 = 24). A portion 61 is formed.

  Since each opening 61 allows light from each LED element 42 to pass therethrough, each opening 61 has a size that allows the LED element 42 to enter the opening 61 when the first spacer 60 is viewed in plan. It has become. In FIG. 6, one LED element 42 is arranged in one opening 61, but a plurality of LED elements may be arranged in one opening.

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

<Wall>
The wall portion 62 includes a first portion 63 extending in the first direction DR1 and a second portion 64 extending in a second direction DR2 different from the first direction DR1 and intersecting the first portion 63. It has. The first portion 63 and the second portion 64 are constituent elements of the wall portion 62, and specifically, are constituent elements of a partition portion 66 described later that partitions the openings 61. The first part and the second part intersect, but the angle formed by 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, the “angle formed by the first part and the second part” means the smaller one of the angles formed by the first part and the second part. Specifically, in the case of the first spacer 60, the angle formed by the first portion 63 and the second portion 64 is an angle represented by θ1 shown in FIG. 5, and a first spacer described later. In the case of 140, the angle formed by the first portion 143 and the second portion 144 is an angle represented by θ1 shown in FIG.

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

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

  Further, like the first spacer 150 shown in FIG. 8, the corner portion 152 </ b> A on the opening 151 side of the wall portion 152 may be curved in a plan view of the first spacer 150. Since the corner portion 152A has a curved shape in a plan view of the first spacer 150, the wall portion 152 is not easily broken even when vibration or impact is applied to the wall portion 152. Since the number of reflections in the portion 152A can be reduced, a reduction in luminance can be suppressed. Similarly to the first spacer 60, the first spacer 150 shown in FIG. 8 includes two or more openings 151 as a light passage region. The wall portion 152 includes a first portion 153 extending in the first direction DR1 and a second portion 154 extending in a second direction DR2 different from the first direction DR1 and intersecting the first portion 153. The wall 152 partitions the openings 151 and surrounds at least one of the openings 151. Since the first spacer 150 is the same as the first spacer 60 except that the corner portion 152A of the wall portion 152 is curved, description thereof will be omitted here.

  The wall portion 62 shown in FIG. 5 includes a frame portion 65 and a partition portion 66 that is located on the inner side of the frame portion 65 and partitions the openings 61. Although the wall part 62 is provided with the frame part 65, for example, like the 1st spacer 160 shown by FIG. 9, the wall part 162 is not provided with a frame part but the well beam comprised only from the partition part 165. It may be in the shape. Similarly to the first spacer 60, the first spacer 160 shown in FIG. 9 also includes two or more openings 161 as a light passage region. The wall portion 162 includes a first portion 163 extending in the first direction DR1 and a second portion 164 extending in a second direction DR2 different from the first direction DR1 and intersecting the first portion 163. The wall 162 partitions the openings 161 and surrounds at least one of the openings 161. However, in FIG. 9, the wall 162 does not surround the periphery of the opening 161 existing on the outermost periphery. Since the first spacer 160 is the same as the first spacer 60 except that the wall portion 162 is composed only of the partition portion 165, the description thereof will be omitted here.

(Frame part)
The frame portion 65 has a quadrangular shape in plan view, but the shape of the frame portion can be appropriately changed according to the shape of the LED mounting substrate and the like. The frame portion 65 is approximately the same size as the wiring substrate 41.

(Partition)
The partition part 66 partitions the openings 61. The partition 66 shown in FIG. 5 is preferably provided integrally with the frame 65. By forming the partition portion 66 integrally with the frame portion 65, a first spacer without a joint can be obtained, so that the assembly process of the surface light source device can be performed rather than configuring the first spacer from a plurality of members. Simplification and reduction of the risk of displacement of the first optical sheet in the vibration test can be achieved. In addition, since the first spacer has no seam, there is no light entering the seam, and optical loss can be reduced. In this specification, “provided integrally” means not only when there is no boundary between the frame portion and the partition portion, that is, when the frame portion and the partition portion are integrally formed, but also the partition portion. It is a concept including the case where is joined to the frame. In the first spacer 60, the frame portion 65 and the partition portion 66 are integrally formed. In addition, although the partition part 66 is preferably provided integrally with the frame part 65 from the viewpoint of increasing the strength of the wall part 62, the partition part may not be provided integrally with the frame part.

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

  It is preferable that the thickness of the wall part 62 is 0.2 mm or more and 10 mm or less. If the thickness of the wall portion 62 is 0.2 mm or more, the function as the support of the first optical sheet 50 can be reliably achieved, and if the thickness is 10 mm or less, the opening diameter of the opening portion 61 is sufficiently large. Therefore, a decrease in luminance can be suppressed. In the present specification, the “wall thickness” means the thickness of the thinnest portion of the wall. The thickness of the wall part 62 does not need to be all uniform. In addition, the thickness of the frame part 65 and the partition part 66 which comprise the wall part 62 may be the same, but does not need to be the same. The lower limit of the thickness of the wall 62 is more preferably 0.5 mm or more.

  As shown in FIG. 3, the side surface 62 </ b> A facing the opening 61 of the wall 62 has a large opening diameter from the bottom surface 60 </ b> A to the top surface 60 </ b> B 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, the emitted light from the LED element 42 can be reflected by the side surface 62A of the wall portion 62 and guided to the first optical sheet 50. Therefore, the surface light source Light can be emitted from the apparatus 20 more efficiently. The 1st spacer 60 provided with the wall part 62 which has such a side surface 62A can be obtained by injection molding, cutting, or a three-dimensional printer, for example. The side surface 62A may be curved in the cross section in the height direction of the first spacer 60, but is preferably linear from the viewpoint of ease of manufacture. Further, the wall portion may be inclined so that the opening diameter of the opening portion increases from the upper surface to the bottom surface of the first spacer.

  The side surface 62A of the wall portion 62 is preferably a rough surface. Specifically, for example, the arithmetic average roughness Ra of the side surface 62A is preferably 0.1 μm or more and 100 μm or less. If the Ra of the side surface 62A is 0.1 μm or more, diffuse reflection increases, so that the in-plane uniformity of luminance can be further improved, and if it is 100 μm or less, the number of reflections does not increase excessively. It is possible to suppress an increase in the frequency with which one spacer 60 absorbs light, and it is possible to suppress a reduction in luminance in-plane uniformity. Ra can be measured using a surface roughness measuring device (product name “SE-3400”, manufactured by Kosaka Laboratory Ltd.) in accordance with JIS B0601: 1999. Ra is measured at 10 locations at random, and is the arithmetic average value of the measured 10 locations of Ra. A method for roughening the side surface 62A is not particularly limited, and examples thereof include a method of containing particles described later in the wall portion 62 and a sandblast method.

  The wall 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. Although it does not specifically limit as a material which comprises the wall part 62, It is preferable to comprise from resin (1st resin) from a viewpoint which is easy to shape | mold and protects the 1st optical sheet 50 grade | etc., From an impact. . Among the first resins, a light-reflective resin such as a white resin is preferable from the viewpoint of increasing the reflectance and guiding light to the first optical sheet 50. The wall portion 62 preferably further contains particles in addition to the resin from the viewpoint of improving light diffusibility. Moreover, since not only visible light but also ultraviolet rays are radiated from the LED element 42, the members in the surface light source device 20 may be deteriorated by the ultraviolet rays. For this reason, it is preferable that the wall part 62 further contains an ultraviolet absorbent in addition to the resin in order to suppress 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 board or the first optical sheet cannot be secured at the wall, and if it exceeds 5 GPa, the surface light source There is a possibility that the first spacer cannot be bent when the apparatus is installed 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.

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

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 or more and 250 parts by mass or less with respect to 100 parts by mass of the first resin.

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

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

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

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

  In the wall part 62, the frame part 65 and the partition part 66 are integrally provided, but the frame part 65 and the partition part 66 may not be provided integrally. That is, like 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 arranged inside the frame portion 175 to obtain the wall portion 172. May be. Further, the wall portion 182 may be obtained by joining two or more wall portions 182A like a first spacer 180 shown in FIG. The first spacers 170 and 180 also include two or more openings 171 and 181 that are light passage regions in addition to the walls 172 and 182, and the walls 172 and 182 have a first direction. First portions 173 and 183 extending in DR1 and second portions 174 and 184 extending in the second direction DR2 and intersecting the first portions 173 and 183 are provided.

  Further, 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 and the second part may be composed of a plurality of divided pieces. In this specification, when the first part and the second part are composed of a plurality of divided pieces, the first part is an aggregate of a plurality of divided pieces arranged in the first direction, An assembly of a plurality of divided pieces arranged in the second direction is defined as a second portion. When the first part and the second part are composed of a plurality of divided pieces, when the first part and the second part are viewed as an aggregate of the divided pieces, the first part and the second part It is only necessary that the two portions intersect, and the divided pieces constituting the first portion and the divided pieces constituting the second portion need not necessarily intersect.

  As a 1st spacer in which the 1st part and the 2nd part were comprised from the some division | segmentation piece, FIG. 11 (A), FIG. 11 (B), FIG. 12 (A), and FIG. The first spacers 190, 200, 210, and 220 shown in FIG. Similarly to the first spacer 60, the first spacers 190, 200, 210, and 220 are respectively light passing regions 191, 201, 211, and 221 and first portions 193 and 203 that extend in the first direction DR1. 213, 223 and second portions 194, 204, 214, 224 extending in a second direction DR2 different from the first direction DR1 and intersecting the first portions 193, 203, 213, 223 And wall portions 192, 202, 212, 222 provided. In FIGS. 11A, 11B, 12A, and 12B, the first portions 193, 203, 213, and 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 portion 193 is composed of a plurality of divided pieces 193A, and the second portion 194 is composed of a plurality of divided pieces 194A. The divided piece 193A and the divided piece 194A intersect each other directly.

  In the first spacer 190, the distance from the first intersection of any divided piece 193A and divided piece 194A to the second intersection of the adjacent divided piece 193A and divided piece 194A in the first direction D1 is 100. It is preferable that the segment 193A exists so that the ratio of the length occupied by the segment 193A is 50% or more between the first intersection and the second intersection. For example, the divided piece 193A constituting the first intersection point extends from the first intersection point to the second intersection point by a length of 25% or more, and the divided piece 193A constituting the second intersection point is the second piece. It is preferable that it extends by a length of 25% or more from the intersection point to the first intersection point. By setting the length of the divided piece 193A to such a length, even when the first portion 193 is constituted by a plurality of divided pieces 193, the contact area with the first optical sheet 50 is reduced. Can be suppressed. For the same reason, in the first spacer 190, in the second direction D2, from the first intersection of any divided piece 193A and divided piece 194A to the second intersection of the adjacent divided piece 193A and divided piece 194A. When the distance up to 100% is assumed, the divided piece 194A exists so that the ratio of the length of the divided piece 193A is 50% or more between the first intersection and the second intersection. preferable. For example, the divided piece 194A constituting the first intersection extends from the first intersection toward the second intersection by a length of 25% or more, and the divided piece 194A constituting the second intersection is the second It is preferable that it extends by a length of 25% or more from the intersection point to the first intersection point.

  In the first spacer 200 shown in FIG. 11B, the first portion 203 includes a plurality of divided pieces 203A and 203B, and the second portion 204 includes a plurality of divided pieces 204A and 204B. Has been. The divided piece 203A and the divided piece 204A intersect each other directly, but the divided piece 203B that exists between the divided pieces 203A does not intersect the divided pieces 204A and 204B, and the divided piece 204B that exists between the divided pieces 204A. Does not intersect with the divided pieces 203A and 203B.

  In the first spacer 200 as well, for the same reason as described above, the second of the adjacent divided piece 203A and the divided piece 204A from the first intersection of the arbitrary divided piece 203A and the divided piece 204A in the first direction D1. When the distance to the intersection point is 100%, the divided pieces 203A, 203A, 203B, the total length of the divided pieces 203A, 203B between the first intersection point and the second intersection point are 50% or more. 203B is preferably present, and in the second direction D1, the distance from the first intersection of any divided piece 203A and divided piece 204A to the second intersection of the adjacent divided piece 203A and divided piece 204A Is set to 100%, the divided pieces 204A and 204B exist so that the ratio of the total length occupied by the divided pieces 204A and 204B is 50% or more between the first intersection and the second intersection. Iko It is preferred.

  In the first spacers 210 and 220 shown in FIGS. 12A and 12B, the first portions 213 and 223 are each composed of a plurality of divided pieces 213A and 223A. The parts 214 and 224 are each composed of a plurality of divided pieces 214A and 224A. The divided pieces 213A, 223A and the divided pieces 214A, 224A do not intersect directly, but the first portions 213, 223 formed of an aggregate of the plurality of divided pieces 213A, 223A arranged in the first direction DR1, and the second The second portions 214 and 224 made of the aggregate of the plurality of divided pieces 214A and 224A arranged in the direction DR2 intersect each other. In this specification, even if it cannot be said that the divided pieces themselves extend in the first direction or the second direction as shown in FIG. 12B, the first part and the second part. If there is at least one segment that does not form an intersection point between any intersection point in the first direction and an adjacent intersection point in the first direction, the first part is regarded as extending in the first direction, and If there is at least one segment that does not constitute an intersection between an arbitrary intersection of the first part and the second part and an adjacent intersection in the second direction, the second part is the second It shall be regarded as extending in the direction.

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

  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 a capability of absorbing light not a little. Therefore, light absorption occurs every time it reaches the wall part, and it is affected by being diffusely reflected by particles for increasing the reflectivity contained in the wall part. However, there is a risk that the luminance will decrease. For this reason, it is preferable to form the opening part penetrated in the width direction of a partition part in a partition part from a viewpoint of a brightness improvement. Specifically, as shown in FIGS. 13 (A), 13 (B), 14 (A), and 14 (B), the partition portions 230, 240, 250, and 260 are the first partition portions. 231, 241, 251, 261, second partition parts 232, 242, 252, 262 adjacent to the first partition parts 231, 241, 251, 261, and first partition parts 231, 241, 251, 261 And the second partitioning portions 232, 242, 252, and 262, and the second partitioning portions 232, 241, 251, and 262 and the second partitioning portions 232, 242, 252, and 262 And third partition portions 233, 243, 253, and 263 having openings 233A, 243A, 253A, and 263A (hereinafter simply referred to as openings 233A, 243A, 253A, and 263A). . The second partition parts 232, 242, 252, 262 are separated from the first partition parts 231, 241, 251, 261 via the openings 234, 244, 254, 264. By having the openings 233A, 243A, 253A, 263A in the third partition parts 233, 243, 253, 263, a part of the light emitted from the LED element 42 passes through the openings 233A, 243A, 253A, 263A. Therefore, light absorption by the third partition parts 233, 243, 253, 263 can be further reduced, and a decrease in luminance can be further suppressed. The second opening may be a through hole or a notch. Openings 233A, 243A, 253A, 263A shown in FIG. 13A and the like are notches. The openings 233A, 243A, 253A, and 263A are formed in the third partition portions 233, 243, 253, and 263, but the first partition portions 231, 241, 251, 261, and the second partition portion 232 are formed. 242, 252, 262 are preferably formed with openings similar to the openings 233 A, 243 A, 253 A, 263 A.

  As shown in FIGS. 13 (A), 13 (B), 14 (A), and 15 (B), the extending direction ED and the first spacer of the third partition portions 233, 243, 253, 263 In the cross section along both of the height directions HD, the total area AR (area surrounded by a two-dot chain line) of the third partition parts 233, 243, 253, 263 and the openings 233A, 243A, 253A, 263A The partition opening ratio, which is the ratio of the area of the openings 233A, 243A, 253A, and 263A, is preferably 30% or more and 70% or less. If the partition area opening ratio is 30% or more, light absorption by the partition sections 230, 240, 250, and 260 can be further suppressed, so that a decrease in luminance can be further suppressed, and the partition section opening ratio is 70% or less. In this case, since the desired strength can be maintained, the function of the first optical sheet 50 as a support can be reliably performed. The area of the third partition is the area from the intersection with the first partition to the intersection with the second partition, and the second opening is the first as shown in FIG. In the case of a notch opened in the height direction of one spacer, the area of the second opening is such that the flat plate is in contact with the first spacer on the side where the second opening is open. And the area of the space between the flat plate and the third partition. Moreover, when the shape of the 2nd opening part provided in the 3rd partition part is changing in the width direction of the 3rd partition part, the total area of a 3rd partition part and a 2nd opening part 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 obtained. Shall.

  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 of the third partition 233 is planar. As shown in FIG. 13B, the bottom surface 243B on the opening 243A side of the third partition 243 may be, for example, a curved surface like an arch. As shown in FIGS. 14A and 14B, the openings 253A and 263A are located on the upper surfaces 250B and 260B opposite to the bottom surfaces 250A and 260A of the partition portions 250 and 260, respectively. Also good. In FIG. 13A, the third partition 233 is provided with one opening 233A between the first partition 231 and the second partition 232. Two or more openings may be provided between the part and the second partition part. Further, in FIG. 13A, in the cross section, the opening 233A is formed so as to be symmetric with respect to the center line of the opening 233A along the height direction of the spacer. It may be asymmetrical.

  At the intersection between the first part and the second part in the wall part, the density of the first spacers is high and the distance between the LED elements is large, so it tends to be dark. For this reason, from the viewpoint of improving the luminance in the vicinity of the intersection between the first portion and the second portion, the intersection is shaved from the first optical sheet side, and the first portion 272 and the second portion 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 of the light passage areas 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 also from the intersection, thereby improving the luminance near the intersection. Can do.

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

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

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

  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 diffusing function in the first optical sheet is not sufficiently exhibited, and when the second optical sheet is viewed in plan, the portion corresponding to the upper surface of the first spacer is darker than the other portions. There is a risk of becoming. Therefore, when the distance d2 is 2 mm or less, the side surface 62A facing the opening 61 of the wall portion 62 of the first spacer 60 is changed from the bottom surface 60A to the upper surface 60B in the height direction of the first spacer 60. It is preferable to incline so that the opening diameter of the opening part 61 may become large. Since the side surface 62A of the first spacer 60 is inclined in this way, it is possible to suppress the portion corresponding to the upper surface 60B of the first spacer 60 from becoming darker than the other portions. When the distance d2 is 2 mm or less (including 0 mm), the ratio of the width of the upper surface 60B to the width of the bottom surface 60A of the first spacer 60 (the width of the upper surface / the width of the bottom surface) is 0.95 or less. Preferably, it is 0.3 or less. The lower limit of this ratio is preferably 0.1 or more from the viewpoint of stably supporting the first optical sheet 50.

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

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

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

  It is preferable that the 2nd optical sheet 70 is comprised from resin. In the present specification, “consisting of resin” means that the resin is a main constituent. The second optical sheet 70 is formed of a translucent resin film made of polycarbonate resin, acrylic resin, or the like, and is formed on one surface side of the resin film. And a lens layer having a lens array or the like.

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

  The height h2 of the second spacer 80 shown in FIG. 3 is larger than the height h1 of the first spacer 60. The height h2 of the second spacer 80 is preferably 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 that the first optical sheet in plan view of the second optical sheet There is a possibility that the portion corresponding to the central portion of each of the partition regions will be brighter than the portion corresponding to the outer edge portion, and if it exceeds 10 mm, the surface light source device may not be thinned. In the present specification, the “height of the second spacer” refers to the second spacer from the bottom surface of the second spacer in the direction perpendicular to the bottom surface that is the inner bottom surface of the housing. It shall mean the distance to the top surface. The height h2 of the second spacer 80 is an arithmetic average value of values obtained by measuring the height of the second spacer 80 at 10 random locations.

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

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

  In addition, an outer side surface 80 </ b> C that is an outer side surface of the second spacer 80 shown in FIG. 3 is in contact with the inner side surface 30 </ b> D of the housing 30. In the present specification, the “outer surface of the second spacer” means a surface opposite to the inner surface that defines the opening of the second spacer. In addition, the phrase “the outer surface of the second spacer is in contact with the inner surface of the housing” in this specification is limited to the case where the outer surface of the second spacer is in direct contact with the inner surface of the housing. In addition, the concept includes a case where a layer that can be ignored in terms of heat conduction, such as a double-sided tape, an adhesive, or an adhesive, is interposed between the outer surface of the second spacer and the inner surface of the housing. is there. In FIG. 3, the outer side surface 80 </ 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 displacement of the second optical sheet 70 with respect to the LED element 42. The method for fixing the second spacer 80 and the housing 30 is not particularly limited, and examples include fixing by adhesion or mechanical fixing means. In FIG. 3, the bottom surface 80 </ b> B of the second spacer 80 and the inner bottom surface 30 </ b> B of the housing 30 are fixed by being bonded via a double-sided tape 113. Here, since the second spacer 80 has a frame shape, the adhesion area with the housing 30 can be increased as compared with the case where the second spacer is composed of a plurality of columnar bodies. The second spacer 80 can be easily fixed. The second spacer 80 and the housing 30 may be bonded via an adhesive or an adhesive instead of the double-sided tape 113.

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

  As shown in FIG. 3, the inner side surface 80 </ b> E that is the inner side surface of the second spacer 80 has an opening diameter of the opening 81 that increases from the inner bottom surface 30 </ b> B 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 surface 80E, light emitted from the first optical sheet 50 is reflected by the inner surface 80E of the second spacer 80, and the second optical sheet 70 is reflected. Therefore, 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 by, for example, injection molding, punching, cutting, or a three-dimensional printer. The inner side surface 80E may be curved in the cross section in the height direction of the second spacer 80, but is preferably linear from the viewpoint of ease of manufacture.

  The 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 constituting the second spacer 80 is not particularly limited, but is made of a 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, a light-reflective resin such as a white resin is preferable from the viewpoint of increasing the reflectivity and further guiding light to the second optical sheet 70.

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

<< Lens sheet >>
The lens sheet 90 has a function of changing the traveling direction of incident light and emitting it from the light exit side. As shown in FIG. 17, the lens sheet 90 changes the traveling direction of light having a large incident angle, such as L1, for example, and emits it from the light-emitting side to intensively improve the luminance in the front direction (collection). In addition to the light function, for example, the light having a small incident angle such as L2 is reflected and returned to the second optical sheet 70 side (retroreflective function). As shown in FIG. 17, the lens sheet 90 includes a resin film 91 and a lens layer 92 provided on one surface of the resin film 91. The lens sheet 90 is arranged so that the lens layer 92 is positioned closer to the reflective polarization separation sheet 100 than the resin film 91.

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

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

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

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

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

  According to the present embodiment, the first spacer 60 includes a first portion 63 extending in the first direction DR1 and a second portion 64 extending in the second direction DR2 and intersecting the first portion 63. Therefore, the contact area with the first optical sheet 50 can be increased compared to a columnar spacer or a simple frame spacer. Thereby, the bending of the 1st optical sheet 50 can be suppressed. Further, since the wall portion 62 of the first spacer 60 partitions the openings 61 and surrounds the periphery of at least one opening 61, the contact area with the first optical sheet 50 can be further increased. Can do.

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

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

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

  When the housing and the first spacer are integrated, it is necessary to arrange each LED mounting board in the opening of the first spacer, and it is necessary to electrically connect each LED mounting board. The arrangement of the LED mounting substrate requires a great deal of labor. On the other hand, in the present embodiment, the first spacer 60 is separate from the housing 30, and therefore, one LED mounting substrate 40 on which a plurality of LED elements 42 are mounted can be used. . Thereby, it is not necessary to arrange a plurality of LED mounting boards, and it is not necessary to electrically connect each LED mounting board, so that it is easy to arrange the LED mounting boards.

  When the first optical sheet is a light transmission / reflection sheet, the distance from the surface of the wiring board to the light transmission / reflection sheet needs to be maintained at a predetermined distance as described above. When integrated, the distance from the surface of the wiring board to the first optical sheet may change depending on the thickness of the wiring board. On the other hand, in the present embodiment, the first spacer 60 is separate from the housing 30, and the first spacer 60 is disposed on the wiring board 41, so that the first spacer 60 depends on the thickness of the wiring board 41. Instead, the distance d1 from the surface 41A of the wiring board 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, the first portions 143, 153, 163, 173, 183, 193, 203, 213 extending in the first direction DR1. 223, and second portions 144, 154, 164, 174, 184 extending in the second direction DR2 and intersecting the first portions 143, 153, 163, 173, 183, 193, 203, 213, 223 , 194, 204, 214, 224 and wall portions 142, 152, 162, 172, 182, 192, 202, 212, 222 are provided, so that the same effect as that of 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. 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 the first optical sheet shown in FIG. It is a top view which shows the arrangement | positioning relationship between 1 and a 1st spacer. 18 and the like, members denoted by the same reference numerals as those in FIG. 1 and the like are the same as those shown in FIG.

<<<<< Image display device >>>>
An image display device 300 shown in FIGS. 19 and 20 includes a direct-type surface light source device 310 and a display panel 120 disposed closer to the viewer than the surface light source device 310.

<<< Surface light source device >>>
A surface light source device 310 shown in FIG. 19 or 20 includes a housing 30, an LED mounting substrate 40, a first optical sheet 320, a first spacer 330, a second optical sheet 70, and a second optical sheet. The spacer 80 is provided. In addition, the surface light source device 310 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 only needs to 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 that faces 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. Examples of the first optical sheet include a light transmission / reflection sheet. The first optical sheet 320 shown in FIGS. 19 and 20 is a light transmission / reflection sheet.

  The first optical sheet 320 is disposed so as 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 board 41. A distance d1 from the surface 41 of the wiring board 41 shown in FIG. 21 to the first optical sheet 320 is 0.6 mm or more and 6 mm or less.

  As shown in FIG. 20, the first optical sheet 320 has at least one or more holes 320A on the surface of the first optical sheet 320 on the first spacer 330 side. A convex portion 335 described later enters the hole 320A. In the present embodiment, since the first optical sheet 320 has a plurality of openings 324 that function as the transmission parts 322, one or more of the openings 324 among the openings 324 are used as the holes 320A. Yes. 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. Not necessarily. The “hole” in the present specification is a concept including not only a through hole but also a hole that does not penetrate, such as a dent. Moreover, even if it is an optical sheet without the opening part which functions as a permeation | transmission part, if it is an optical sheet which has a hole part into which the convex part 335 enters, it is applicable.

  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 the thickness of a 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 includes a partition region 321 that is divided into a plurality of parts in a plan view.

<Division area>
The partition region 321 is preferably divided according to the number of LED elements 42. In FIG. 21, 4 vertical areas × 6 horizontal areas = 24 partition regions 321 are formed corresponding to LED elements (4 vertical elements × 6 horizontal elements = 24 elements). In FIG. 21, the boundary line is indicated by a dotted line. However, the boundary line is not actually formed, the boundary line is a virtual line, and the partition area 321 is also a virtual area.

  As shown in FIG. 21, each partition region 321 includes a plurality of transmission parts 322 that transmit part of the light from the LED element 42, and a plurality of reflection parts 323 that reflect part of the light from the LED element 42. It consists of Similar to the transmissive part 52 and the reflective part 53, the transmissive part 322 and the reflective part 323 are configured in a predetermined pattern.

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

  In the central portion 321A of each partition region 321, the area ratio is preferably reflection portion> transmission portion. From the viewpoint of improving the in-plane uniformity of luminance, the central portion 321A of each partition region 321 is reflective. It is more preferable to configure only the portion 323. Moreover, in the outer edge part 321B of each partition area | region 321, it is preferable that area ratio is the transmission part> reflection part. 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 part 322 in the outer edge part 321B is more preferably 60% or more, and preferably 70% or more.

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

  The first optical sheet 320 is a reflective sheet such as, for example, 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 transmission part 322 that transmits light, and a part other than the opening 324 in the first optical sheet 320 functions as a reflection part 323 that reflects light. The openings 324 have an arbitrary shape (for example, a circular shape or a rectangular shape), and are dispersedly arranged so as not to be connected to each other along a predetermined pattern. The opening 324 can be formed by press punching or punching with an engraving blade. Press punching is an effective manufacturing method for mass production because of its excellent running cost and productivity.

<< First spacer >>
The first spacer 330 is for separating the first optical sheet 320 from the LED mounting substrate 40. The first spacer 330 has a function of maintaining a distance d1 from the surface 41A of the wiring board 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 not less than 0.5 mm and not more than 5 mm for the same reason as described in the column of the first spacer 60. The height h1 of the first spacer 330 is an arithmetic average value of values obtained by randomly measuring the height of the first spacer 330 at ten locations.

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

  It is preferable that the first spacer 330 and the first optical sheet 320 are fixed by a method similar to the fixing method of 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 bonded via a double-sided tape 112. By fixing the first spacer 330 and the first optical sheet 320, the 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 includes an opening 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 portion 332 including 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 portion 332 on the first optical sheet 320 side One or more convex portions 335 are provided. The wall portion 332 partitions the openings 331 and surrounds at least one opening 331. The “convex portion” in the present specification is a concept including protrusions. As shown in FIG. 23, the first spacer 330 is aligned with the first optical sheet 320.

<Opening>
Since the opening 331 is similar to the opening 61, the description thereof is omitted here.

<Wall>
The wall portion 332 includes the first portion 333 and the second portion 334 as described above. The first portion 333 and the second portion 334 are constituent elements of the wall portion 332, and specifically, are constituent elements of a partition portion 337 described later that partitions the openings 331. Similar to the wall portion 62, the wall portion 332 shown in FIG. 22 includes a frame portion 336 and a partition portion 337 that is positioned inside the frame portion 336 and partitions the openings 331. Since the wall part 332, the frame part 336, and the partition part 337 are the same as the wall part 62, the frame part 65, and the partition part 66, description is abbreviate | omitted here. In addition, if the wall part of the 1st spacer of this embodiment is also provided with the 1st part and the 2nd part, wall part 142,152,162,172,182,192,202,212,222 and It may be the same shape.

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

  Although the shape of the convex part 335 is not specifically limited, For example, cone shape, truncated cone shape, pyramid shape, truncated pyramid shape, dome shape, and indefinite shape are mentioned, for example.

  From the viewpoint of not affecting the optical performance of the first optical sheet 320, the height of the convex portion 335 is preferably set to be equal to or less than the thickness of the first optical sheet 320 (less than the height of the opening 324). Further, from the viewpoint of suppressing the displacement of the first optical sheet 320, the lower limit of the height of the convex portion 335 is more preferably ¼ or more of the thickness of the first optical sheet 320.

  Although the diameter and width of the convex portion 335 are not particularly limited, the first optical sheet 320 has a plurality of openings having different diameters, and therefore does not enter the opening 324 smaller than the target opening 324. It is preferable that the diameter is such that there is not.

  One or more protrusions 335 may be formed as a whole of the first spacer 330, but a plurality of protrusions 335 are preferably formed from the viewpoint of suppressing the displacement of the first optical sheet 320. Furthermore, from the viewpoint of further suppressing the positional deviation of the first optical sheet 320, the convex portions 335 are formed at least at four places so that a quadrangle is drawn by the convex portions 335 in the plan view of the first spacer 330. Preferably it is.

  The convex part 335 is provided integrally with the frame part 336 and the partition part 337. The first spacer 330 having the convex portion 335 can be manufactured by injection molding, cutting, or a three-dimensional printer. In addition, it is possible to separately produce a convex part and fix the convex part to at least one of the frame part and the partition part by an adhesive or the like or mechanical fixing. When fixed to the partition part, the convex part may be peeled off from the frame part and / or the partition part. Therefore, the convex part and the frame part and / or the partition part are integrally formed by injection molding or the like. Is preferred.

  According to the present embodiment, since the hole 320A is provided in the first optical sheet 320 and the convex portion 335 is provided in the first spacer 330, the first optical sheet 320 is aligned with the LED element 42. It becomes easy, and even if it is a case where an impact is applied to the surface light source device due to vibrations of the vehicle or the like or some factor, 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 a wall portion 332 including a first portion 333 and a second portion 334 that intersects the first portion 333, the first spacer 330 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 vibrations of the vehicle or the like or for some reason, the swing width of the first optical sheet 320 is smaller than when the columnar spacer is used. Therefore, the position shift of the first optical sheet 320 with respect to the LED element 42 can be suppressed. In addition, since the positional deviation of the first optical sheet 320 that is a light transmitting / reflecting sheet with respect to the LED element 42 can be suppressed, when an impact is applied to the surface light source device 310 due to vibration of the vehicle or the like or for some reason. Even if it exists, the fall of the in-plane uniformity of a brightness | luminance can be suppressed. In addition, when the hole is provided in the second optical sheet 70 and the convex portion is provided in the second spacer 80, the alignment of the second optical sheet 70 with respect to the LED element 42 is facilitated and the LED element is similarly provided. The positional deviation of the second optical sheet 70 with respect to 42 can be suppressed.

  In a surface light source device for vehicles, even when a vibration test is performed, it is required that the first optical sheet is not misaligned with respect to the LED element, the first spacer, or the like is not damaged. On the other hand, according to this embodiment, the first optical sheet 320 is provided with a hole 320A, the first spacer 330 is provided with a convex portion 335, and the first spacer 330 is connected to the first portion 333. Since the wall portion 332 including the first portion 333 and the second portion 334 intersecting with the first portion 333 is provided, even when the vibration test is performed, the positional deviation of the first optical sheet 320 with respect to the LED element 42 Can be suppressed. Further, since the first spacer 330 is higher in rigidity than the columnar spacer, the first spacer 330 is not easily damaged even when a vibration test is performed. For this reason, the surface light source device 310 can be suitably used for in-vehicle use.

  Further, 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 center of the optical sheet. In particular, when the optical sheet is a light transmissive reflective sheet, the light transmissive reflective sheet has a pattern of a transmissive portion and a reflective portion in each partition region. If the distance from the transmission / reflection sheet changes, the in-plane uniformity of luminance may be reduced. On the other hand, according to the present embodiment, the first spacer 330 includes the wall portion 332 including the first portion 333 and the second portion 334 that intersects the first portion 333. Compared with the columnar spacer, the contact area with the first optical sheet 320 can be increased. Thereby, the bending of the 1st optical sheet 320 can be suppressed. Further, since the first spacer 330 can suppress the bending of the first optical sheet 320 that is a light transmitting and reflecting sheet, the distance between the wiring board 41 and the first optical sheet 320 is kept at a predetermined distance. And in-plane uniformity of luminance can be improved.

  Applications of the image display devices 10 and 300 and the surface light source devices 20 and 310 of the first embodiment and the second embodiment are not particularly limited. For example, for television applications, in-vehicle applications, and advertising media applications such as signboards. Can be used. Among these, since the image display devices 10 and 300 and the surface light source devices 20 and 310 can withstand a vibration test, they can be suitably used for in-vehicle applications.

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

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

  Moreover, the light transmission reflection sheet was produced. The light transmissive reflection sheet was produced by forming a plurality of openings penetrating in the thickness direction in a predetermined pattern on a foamed polyethylene terephthalate film having a thickness of 0.5 mm by press punching. As a result, a light transmitting / reflecting sheet having 60 partition regions in total of 5 vertical portions × 12 horizontal portions each including a transmission portion and a reflection portion was obtained. In the light transmission / reflection sheet, the size of each partition region was 22 mm long × 24.2 mm wide, and the aperture ratio gradually increased from the center of each partition region toward the outer edge.

  Moreover, the 1st spacer was produced. The first spacer has a lattice shape, and 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 vertical × 12 horizontal penetrating in the height direction of the first spacer of 20 mm long × 22.4 mm wide, and 111 mm long. A rectangular frame portion having a width of 290 mm, a width of 2 mm, and a height of 2 mm, and a wall portion having a partition portion having a width of 2 mm and a height of 2 mm, which is formed integrally with the frame portion. It was a thing. The wall portion surrounds all the openings. Further, the partition portion extends in the first direction along the lateral direction of the first spacer, extends in the second direction along the longitudinal direction of the first spacer, and the first portion. The second part intersected.

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

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

<Example 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 the polycarbonate resin to produce the first spacer. .

<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 shape made of polycarbonate resin and having a diameter of 5 mm and a height of 2 mm, and one spacer was arranged between each LED element. The columnar first spacers were fixed to the flexible wiring substrate and the light reflecting / transmitting sheet through a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation).

<Comparative Example A2>
In Comparative Example A2, the same procedure as in Example A1 was used except that instead of the lattice-shaped first spacer, a frame-shaped first spacer composed of one opening having no partitioning portion was used. An LED surface light source device was obtained. The first spacer used in Comparative Example A2 is composed of a polycarbonate resin having a size of 111 mm × 290 mm, a width of 2 mm, and a height of 2 mm, and one frame having a size of 107 mm × 286 mm inside the frame. And an opening. The first spacer in a frame shape was fixed to the flexible wiring substrate and the light reflecting / transmitting sheet through a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation).

<Bending evaluation>
In the LED surface light source devices according to Examples A1 and A2 and Comparative Examples A1 and A2, it was visually evaluated whether or not the light transmission / reflection sheet was bent. In addition, a bending shall be confirmed with the light transmission reflection sheet before the vibration test mentioned later.
○: Deflection was not confirmed in the light transmission reflection sheet.
X: Deflection was confirmed in the light transmission reflection sheet.

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

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

The in-plane uniformity of the luminance is evaluated by using the central region in the measurement region as long as 22.4 mm × horizontal 146.4 mm, and the maximum luminance (Lv _max ) and minimum luminance (Lv _min ) in the luminance distribution within the evaluation range are used. 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 brightness uniformity before the vibration test and the in-plane brightness uniformity after the vibration test obtained above, the rate of change in the in-plane brightness before and after the vibration test is obtained, and before and after the vibration test. The degree to which the in-plane luminance uniformity was reduced was evaluated. The evaluation criteria were as follows.
A: The rate of change of the in-plane uniformity of luminance before and after the vibration test was within 10%.
X: The rate of change in in-plane uniformity of luminance before and after the vibration test exceeded 10%.
The rate of change in in-plane uniformity of brightness before and after the vibration test is the difference between the in-plane uniformity of brightness before the vibration test and the in-plane uniformity of brightness after the vibration test (the in-plane uniformity of brightness before the vibration test). In-plane uniformity of luminance after vibration test).

<Appearance evaluation>
In the LED surface light source devices according to Examples A1 and A2 and Comparative Examples A1 and A2, the appearance of the first spacer after the vibration test was visually observed and evaluated. The evaluation results were based on the following criteria.
○: In the first spacer, damage such as cracking or breaking was not confirmed.
X: In the first spacer, damage such as cracking or breaking was confirmed.

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

<Measurement of molding shrinkage>
The molding shrinkage rate of the wall portion of the first spacer according to Examples A1 and A2 was measured under the following conditions. The measurement of the molding shrinkage rate of the wall portion is performed based on JIS K6911: 1995. In the measurement of the molding shrinkage rate of the wall portion, the resin constituting the wall portion is melted by heating the wall portion. The molded product obtained by pouring the resin into a mold and solidifying the resin was used.

<Heat resistance test>
The first spacers according to Examples A1 and A2 were each subjected to a heat resistance test in which the first spacer was allowed to stand for 1000 hours in an environment of 85 ° C., and the appearance of the first spacer after the test was evaluated. The evaluation criteria were as follows.
○: The shape of the first spacer was not substantially changed 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 remarkably changed before and after the heat resistance test.

The results are shown in Tables 1 and 2.

  The results will be described below. In Comparative Example A1, since the first spacer was columnar, it was confirmed that the light transmitting / reflecting sheet was bent. In Comparative Example A1, the in-plane uniformity of luminance before the vibration test was low. This is presumably because the light transmission / reflection sheet was bent. Furthermore, in Comparative Example A1, the in-plane uniformity of luminance after the vibration test was clearly lower than the in-plane uniformity of luminance before the vibration test. This is probably because the first spacer was a columnar shape, so that the rigidity was low, and the light transmission / reflection sheet was displaced from the LED element by the vibration test.

  In Comparative Example A2, since the first spacer was a frame having no partition part, the light transmission / reflection sheet was confirmed to be bent. In Comparative Example A2, the in-plane uniformity of luminance before the vibration test was low. This is presumably because the light transmission / reflection sheet was bent. Further, in Comparative Example A2, the in-plane uniformity after the vibration test was clearly reduced as compared with the in-plane uniformity before the vibration test. This is because the first spacer was a frame-like shape having no partition part, so that the rigidity was low, and it was considered that the light transmission / reflection sheet was displaced from the LED element by the vibration test. It is done.

  On the other hand, in Example A1 and A2, since the 1st spacer was comprised from the wall part which has a frame part and a partition part, bending was not confirmed by the light transmissive reflective sheet. In Example A1, the in-plane uniformity of luminance before the vibration test was high. This is considered because the light transmission reflection sheet was not bent. Furthermore, in Example A1, the deterioration of the in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed as compared with Comparative Examples A1 and A2. This is because the first spacer is composed of a wall part having a frame part and a partition part, so that the rigidity is high, and the positional deviation of the light transmission / reflection sheet with respect to the LED element hardly occurs even in the vibration test. It is considered a thing.

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

  Moreover, the light transmission reflection sheet was produced. The light transmissive reflection sheet was produced by forming a plurality of openings penetrating in the thickness direction in a predetermined pattern on a foamed polyethylene terephthalate film having a thickness of 0.5 mm by press punching. Here, the opening part of the magnitude | size which can enter a convex part was formed in the position corresponding to the convex part provided in a 1st spacer among opening parts. As a result, a light transmitting / reflecting sheet having 60 partition regions in total of 5 vertical portions × 12 horizontal portions each including a transmission portion and a reflection portion was obtained. In the light transmission / reflection sheet, the size of each partition region was 22 mm long × 24.2 mm wide, and the aperture ratio gradually increased from the center of each partition region toward the outer edge.

  Moreover, the 1st spacer was produced. The first spacer has a lattice shape, and was produced by injection molding using a polycarbonate resin. The first spacer is a rectangular frame portion having a size of 111 mm long × 290 mm wide, 2 mm wide and 2 mm high, and the height of the first spacer having a size of 20 mm long × 22.4 mm wide inside the frame portion. Openings as light passage regions arranged in a matrix of 5 vertical x 12 horizontal penetrating in the vertical direction, and a width of 2 mm and a height of 2 mm provided between the openings and provided integrally with the frame And a convex portion having a height of 0.2 mm provided integrally with the partitioning portion at four locations on the surface of the partitioning portion disposed on the light transmitting and reflecting sheet side. Further, the partition portion extends in the first direction along the lateral direction of the first spacer, extends in the second direction along the longitudinal direction of the first spacer, and the first portion. The second part intersected.

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

  And the produced LED mounting board | substrate was arrange | positioned so that the LED element may become an upper side in the housing | casing main body made from aluminum which has a storage space whose magnitude | size is 117 mm x 310 mm x height 7 mm. Next, the first spacer produced as described above was fixed to the surface of the flexible wiring board in the LED mounting board via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). The first spacer was arranged such that a convex portion was located on the side opposite to the flexible wiring board side, and light from each LED element passed through the opening of the first spacer. After disposing the first spacer, the light-transmitting / reflecting sheet prepared above was fixed on the first spacer via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). Here, in the arrangement of the light transmissive reflection sheet, while aligning the light transmissive reflection sheet with respect to the first spacer so that the convex portion of the first spacer enters the opening of the light transmissive reflection sheet, A light transmissive reflection sheet was disposed. In addition, the boundary part between the division area | regions in a light transmissive reflection sheet was a position of the partition part of a 1st spacer. Next, the produced second spacer is arranged between the housing main body, the LED mounting substrate, and the first spacer, and the second spacer is placed on the bottom surface of the housing main body with a double-sided tape (product name “No. 5000NS”). ”, Manufactured by Nitto Denko Corporation). Furthermore, a light diffusion sheet having a length of 117 mm × width of 310 mm and a thickness of 1.5 mm was disposed on the second spacer. Finally, a lid having an opening with a size of 110 mm in length and 303 mm in width was fitted into the housing body to obtain a surface light source device. The distance from the surface of the flexible wiring board to the light transmissive reflecting sheet is 2 mm, and the distance from the surface of the flexible wiring board to the light diffusing sheet is 4.8 mm, between the light transmissive reflecting sheet and the light diffusing sheet. 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 in 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 columnar shape made of polycarbonate resin and having a diameter of 5 mm and a height of 2 mm, and one spacer was arranged between each LED element. The columnar first spacer used in Comparative Example B1 was fixed to the flexible wiring substrate and the light reflecting / transmitting sheet through a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). In addition, the columnar first spacer used in Comparative Example B1 did not have a convex portion on the surface on the light transmission / reflection sheet side.

<Comparative Example B2>
In Comparative Example B2, a surface light source device was obtained in the same manner as in Example B1 except that a frame-shaped first spacer having no partitioning portion was used instead of the lattice-shaped first spacer. . The first spacer used in Comparative Example B2 is a frame portion 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 × width 286 mm inside the frame portion. And an opening. In addition, the frame-shaped first spacer used in Comparative Example B2 was fixed to the flexible wiring substrate and the light reflecting / transmitting sheet via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). . Further, the frame-shaped first spacer used in Comparative Example B2 was not provided with a convex portion on the surface on the light transmission / reflection sheet side.

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

<Bending evaluation>
In the surface light source devices according to Example B1 and Comparative Examples B1 and B2, it was visually evaluated whether or not the light transmission / reflection sheet was bent. In addition, a bending shall be confirmed with the light transmission reflection sheet before the vibration test mentioned later.
○: Deflection was not confirmed in the light transmission reflection sheet.
X: Deflection was confirmed in the light transmission reflection sheet.

<Appearance evaluation>
In the surface light source devices 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. The evaluation results were based on the following criteria.
○: In the first spacer, damage such as cracking or breaking was not confirmed.
X: In the first spacer, damage such as cracking or breaking was confirmed.

The results are shown in Table 3 below.

  The results will be described below. In Comparative Example B1, the in-plane brightness uniformity after the vibration test was clearly lower than the in-plane brightness uniformity before the vibration test. This is because the first spacer was not provided on the convex portion, and the first spacer was columnar, and the rigidity was low. It is thought that a gap has occurred. Moreover, in Comparative Example B1, since the first spacer was columnar, it was confirmed that the light transmission / reflection sheet was bent. In Comparative Example B1, the in-plane uniformity of luminance before the vibration test was low. This is considered to be because the alignment accuracy of the light transmission / reflection sheet with respect to the LED element is low and / or the light transmission / reflection sheet is bent.

  In Comparative Example B2, the in-plane uniformity after the vibration test was clearly lower than the in-plane uniformity before the vibration test. This is because the first spacer was not provided on the convex portion, and the first spacer was a frame-like shape having no partition part, and the rigidity was low. It is considered that the light transmitting / reflecting sheet has been displaced. Moreover, since the 1st spacer was a frame shape which does not have a partition part, bending was confirmed by the light transmissive reflection sheet. In Comparative Example B2, the in-plane uniformity of luminance before the vibration test was low. This is considered to be because the alignment accuracy of the light transmission / reflection sheet with respect to the LED element is low and / or the light transmission / reflection sheet is bent.

  On the other hand, in Example B1, the fall of the in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed more than Comparative Examples B1 and B2. This is because the first spacer is provided with a convex portion and enters the opening of the light transmitting and reflecting sheet, and the first spacer has a frame portion and a partition portion, and has high rigidity. It is considered that the light transmission / reflection sheet was not substantially displaced from the LED element even in the vibration test. In Example B1, since the 1st spacer was comprised from the frame part and the partition part, bending was not confirmed by the light transmissive reflective sheet. In Example B1, the in-plane uniformity of luminance before the vibration test was high. This is probably because the first spacer was provided with a convex portion, so that the alignment accuracy of the light transmission / reflection sheet with respect to the LED element was high and / or the light transmission / reflection sheet was not bent. .

DESCRIPTION OF SYMBOLS 10, 300 ... Image display apparatus 20, 310 ... Surface light source device 40 ... LED mounting board 41 ... Wiring board 42 ... LED element 50, 320 ... 1st 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, 332 ... walls 63, 143, 153, 163, 173, 183, 193, 203, 213, 223, 333 ... 1st part 64, 144, 154, 164, 174, 184, 194, 20 214, 224, 334, second portion 65, 336, frame 66, 337, partition 70, second optical sheet 80, second spacer 335, convex portion DR1, first direction DR2, second. Direction

Claims (1)

A spacer that is used in a surface light source device that includes an optical sheet and a facing member that faces the optical sheet, and that is disposed between the optical sheet and the facing member, and separates the optical sheet from the facing member. There,
A wall portion comprising 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 light passage region that exists in a region other than the wall portion and allows light to pass through;
A spacer.

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