JP2018106970A - LED backlight device and LED image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED backlight device which is bendable and an LED display device including the same.SOLUTION: An LED backlight device includes: an LED mounting substrate including a plurality of LED elements 42 mounted on a flexible wiring board 41; a first optical sheet 50 arranged so as to oppose to the plurality of LED elements; a second optical sheet 70 arranged on a light emission side of the first optical sheet; a first spacer 60 arranged between the flexible wiring board and the first optical sheet, constituted by first resin and for separating the first optical sheet with respect to the flexible wiring board; and a frame-like second spacer 80 arranged so as to surround an outer peripheral surface 50A of the first optical sheet and an outer peripheral surface 60A of the first spacer 60, constituted by second resin, and for separating the second optical sheet with respect to the first optical sheet. The Young's modulus of the second resin constituting the second spacer is smaller than the Young's modulus of the first resin constituting the first spacer.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an LED backlight device and an LED image display device.

  2. Description of the Related Art In recent years, LED image display devices that have been rapidly spread generally include a display screen such as a liquid crystal display panel and an LED backlight that illuminates the display screen from the back side. At present, in an LED image display device, an edge light type LED backlight device is usually used in many cases, but from the viewpoint of brightness, the use of a direct type LED backlight device has been studied.

  In the direct type LED backlight, a plurality of optical sheets are arranged on the LED element from the viewpoint of improving the in-plane uniformity of luminance on the light emitting surface of the LED backlight device (see Patent Document 1). ). As such an optical sheet, for example, a light diffusing sheet and a white or other resin reflecting material sheet that is disposed between the LED element and the light diffusing sheet and reflects light from the LED element, the LED element from directly above the LED element. In some cases, a light transmitting / reflecting sheet having an opening pattern in which the opening gradually increases toward the periphery of the sheet is used.

  In order to improve the in-plane uniformity of luminance by using such a light transmission / reflection sheet and light diffusion sheet, the light transmission / reflection sheet is separated from the wiring board on which the LED elements are mounted, and light transmission / reflection is performed. It is necessary to separate the light diffusion sheet from the sheet. For this reason, usually, a plurality of columnar spacers are arranged between the wiring board and the light transmission / reflection sheet and between the light transmission / reflection sheet and the light diffusion sheet.

JP 2010-272245 A

  By the way, in the field of automobiles, for example, design is very important. Currently, image display apparatuses applied to such fields are not only expected to have a function of displaying video, but also are required to be harmonized with the whole in terms of design. For this reason, from the viewpoint of designability, a curved LED image display device is now desired. Also in the advertising field, a curved LED image display device as an advertising medium that can be installed along the surface of a cylindrical column is desired from the viewpoint of design and the like. Therefore, since the LED backlight device incorporated in the LED image display device also needs to be curved, a bendable one is desired.

  The present invention has been made to solve the above problems. That is, an object is to provide a bendable LED backlight device and an LED display device including the same.

  According to one aspect of the present invention, a flexible wiring board and an LED mounting board including a plurality of LED elements mounted on one surface of the flexible wiring board are disposed so as to face the plurality of LED elements. The first optical sheet, the second optical sheet disposed on the light emitting side of the first optical sheet, the flexible wiring board and the first optical sheet are disposed between the first optical sheet and the first optical sheet. A first spacer that is made of resin and separates the first optical sheet from the LED mounting substrate; and an outer peripheral surface of the first optical sheet and an outer peripheral surface of the first spacer. And a frame-shaped second spacer that is made of a second resin and that separates the second optical sheet from the first optical sheet, before the second spacer is formed Young's modulus of the second resin may be smaller than the Young's modulus of the first resin constituting the first spacer, LED backlight device is provided.

  In the LED backlight device, the first spacer is fixed to the flexible wiring board and the first optical sheet, and the first spacer is positioned inside the frame portion and the frame portion. A plurality of openings penetrating in the height direction of the first spacer and allowing light from the LED elements to pass therethrough, and located between the openings and provided integrally with the frame portion. You may have a crosspiece.

  In the LED backlight device, the first spacer may have a lattice shape or a honeycomb shape.

  In the LED backlight device, the thickness of the second optical sheet may be larger than the thickness of the first optical sheet.

  In the LED backlight 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 from the LED element. And a plurality of reflecting portions that reflect a part of the light from the LED element, and an aperture ratio that is an area ratio of the transmission portion in each partition region is from the central portion of the partition region to the partition region It may be gradually increased toward the outer edge portion.

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

  According to one embodiment of the present invention, a bendable LED backlight device can be provided. Moreover, according to the other aspect of this invention, an LED image display apparatus provided with such an LED backlight apparatus can be provided.

It is a disassembled perspective view of the LED image display apparatus which concerns on embodiment. It is a schematic block diagram of the LED image display apparatus which concerns on embodiment. It is a partial expanded sectional view of the LED backlight apparatus which concerns on embodiment. It is a top view of the 1st optical sheet shown by FIG. It is a top view of the other 1st optical sheet which concerns on embodiment. It is a top view of the 1st spacer shown by FIG. It is a top view which shows the arrangement | positioning relationship between the 1st optical sheet shown by FIG. 1, and a 1st spacer. It is a top view of the other 1st spacer concerning an embodiment. It is a top view which shows the arrangement | positioning relationship between the 1st spacer shown by FIG. 1, and a 2nd spacer. It is sectional drawing of the lens sheet shown by FIG.

  Hereinafter, an LED backlight device and an LED image display device according to an 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 LED image display device according to the present embodiment, FIG. 2 is a schematic configuration diagram of the LED image display device according to the present embodiment, and FIG. 3 is an LED backlight device according to the present embodiment. FIG. 4 is a plan view of the first optical sheet shown in FIG. 1, FIG. 5 is a plan view of another first optical sheet according to the embodiment, and FIG. 6 is a plan view of the first optical sheet shown in FIG. FIG. 7 is a plan view showing the arrangement relationship between the first optical sheet and the first spacer shown in FIG. FIG. 8 is a plan view of another first spacer according to the embodiment, FIG. 9 is a plan view showing the positional relationship between the first spacer and the second spacer shown in FIG. 1, and FIG. It is sectional drawing of the lens sheet shown by FIG.

<<<<< LED image display device >>>>
The LED image display device 10 illustrated in FIGS. 1 and 2 includes a direct-type LED backlight device 20 and a display panel 120 disposed on the viewer side of the LED backlight 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 112 disposed on the light exit side, a polarizing plate 121 and a polarizing plate 122. And a liquid crystal cell 123 disposed between them. As the polarizing plates 121 and 122 and the liquid crystal cell 123, known polarizing plates and liquid crystal cells can be used.

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

  Since the vehicle-mounted LED backlight device is disposed in a very narrow space in the vehicle, it is desired to make the LED backlight device thinner than a general LED backlight device. For this reason, the total thickness of the LED backlight device 20 is preferably 15 mm or less, and more preferably 10 mm or less, from the viewpoint of reducing the thickness. The total thickness of the “LED backlight device” means the distance from the outer bottom surface 30C of the housing 30 shown in FIG. 2 to the surface 100A of the reflective polarization 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 FIGS. 1 and 2 includes a housing body 31 having a housing space 30A, and a frame-shaped lid 32 that covers the housing space 30A of the housing body 31 and has an opening 30E. ing. In the housing 30, the inner bottom surface 30 </ b> 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. When the LED backlight device 20 is bent, if the case 30 can be bent, the case 30 may be bent together with the contents accommodated in the case 30, but the case 30 is bent in advance. It is preferable to use what was used.

<< LED mounting board >>
The LED mounting substrate 40 includes a flexible wiring substrate 41 and a plurality of LED elements 42 mounted on one surface (hereinafter referred to as “surface”) 41 </ b> A of the flexible wiring substrate 41. “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.

  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.

<Flexible wiring board>
In the flexible 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 film 50. Are stacked. However, the flexible wiring board 41 may not include the insulating protective film 45 and the reflective layer 46. The metal wiring part 44 is preferably bonded to the resin film 43 by a dry laminating method through an adhesive layer 47. Further, the metal wiring portion 44 is electrically connected to the LED element 42 via the solder layer 48.

(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 applied, and a temperature rise rate of 2 ° C./min is 120. Measure the amount of shrinkage (in%) at that time, measure the temperature and the amount of shrinkage, and read the temperature that deviates from the 0% baseline due to shrinkage. Is the heat shrinkage start temperature. The heat shrinkage starting temperature is an arithmetic average value obtained by measuring three times.

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

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

  The thickness of the resin film 43 is not particularly limited, but is generally 10 μm or more and 500 μm or less from the viewpoint of not being a bottleneck as a heat dissipation path, having heat resistance and insulation, and a balance of manufacturing costs. It is preferable that Moreover, it is preferable that it is the said thickness range also from a viewpoint of maintaining favorable productivity at the time of manufacturing by a roll-to-roll system. The thickness of the resin film 43 is obtained by measuring the thickness at any 10 locations using a thickness measuring device (product name “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation) and calculating the average value thereof. And The lower limit of the thickness of the resin film 43 is 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. Furthermore, since deterioration of peripheral members such as a resin film due to heat can be prevented, the product life of the LED image display device incorporating the LED backlight 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 flexible wiring board 41, preferably, a range of 80% or more, more preferably 90%, most preferably 95% or more of one surface of the resin film 43 is covered with the metal wiring part 44. Is preferred. Accordingly, the LED elements 42 can be arranged with high density, and the excessive heat generated can be sufficiently diffused quickly through the metal wiring portion 44 and radiated to the outside via the resin film 43. Therefore, the LED backlight 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 flexible wiring substrate 41 and is not particularly limited, but may be 10 μm or more and 50 μm or less as an example. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 44 is preferably 10 μm or more. In addition, if the thickness of the metal wiring portion is less than 10 μm, the influence of heat shrinkage of the resin film 43 is large, and warpage after the processing is likely to increase during the solder reflow processing. The thickness is preferably 10 μm or more. On the other hand, when the thickness of the metal wiring portion is 50 μm or less, it is possible to maintain sufficient flexibility of the wiring substrate, and it is possible to prevent a decrease in handling properties due to an increase in weight. The thickness of the metal wiring portion 44 can be measured by the same method as that for the resin film 43.

(Insulating protective film)
The insulating protective film 45 mainly improves the migration resistance characteristics of the flexible 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 41A of the flexible wiring board 41 so as to cover the area excluding the LED element mounting area for the purpose of improving the light emission capability of the LED backlight 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 LED backlight device may not be thinned. The thickness of the reflective layer 46 can be measured by the same method as the thickness of the insulating protective film 45.

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

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

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

<< LED element >>
The LED element 42 is a light emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. As LED elements, there are known a structure in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element, and a structure in which both the P-type and N-type electrodes are provided on one side of the element. An LED element can also be used for the LED backlight 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 flexible 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 flexible wiring board 41. The number of the LED elements 42 mounted on the flexible 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 flexible wiring board 41 shown in FIG. 3 to the first optical sheet 50 is 0.6 mm or more and 6 mm or less. The “distance from the surface of the wiring board to the first optical sheet” in the present specification includes a reflective layer on the insulating protective layer like the flexible wiring board 41, and the surface of the reflective layer is the wiring board. When it is the surface, it 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 flexible wiring board also has the function of the reflective layer When the surface of the insulating protective layer is the surface of the flexible 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 flexible wiring board side in the first optical sheet is the flexible 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 flexible wiring board 41 side of the resin film 54 as in the first optical sheet 50, the surface of the reflective layer 55 on the flexible wiring board 41 side. And

  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 transmission reflection sheet is less than 25 μm, a desired reflectance may not be obtained, and if it exceeds 1 mm, the LED backlight device may not be thinned. The thickness of the first optical sheet 50 is the thickness of the reflecting portion 53 described later, and is the thickness of any 10 locations using a thickness measuring device (product name “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation). Can be obtained by measuring 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. 3, 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. The “aperture ratio” in the present specification means that when one partition region is divided into square cells having an equal area that is equivalent to an appropriate ratio of about 25 to 100, transmission through each cell is performed. It means the area ratio of the part. The method of defining the squares having the same area in one partition region is arbitrary. For example, it is desirable to set so that the number of transmission parts 52 present in each square is approximately equal. In addition, the “aperture ratio” defines a plurality of concentric circles centered on the center point of one partition region at equal intervals from the central region to the outer region located outside the central region. You may obtain | require by calculating the area ratio of the permeation | transmission part in each area | region between circumference | surroundings similarly to the above. According to this calculation method, the above “opening ratio” can be defined also for a partitioned area other than a general opening arrangement in which rectangular openings are arranged in a grid pattern. In each partition region 51, the aperture ratio only needs to gradually increase from the central portion 51A toward the outer edge portion 51B. For example, the aperture ratio is constant in a limited partial range near the central portion or the outer edge portion. An area may exist.

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

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

<Transmission part>
The transmissive portion 52 is a region where the reflective layer 55 is not formed on any of both surfaces of the resin film 54 and is a region where both surfaces of the resin film 54 in FIG. 3 are exposed. As the resin film 54, a conventionally known transparent film is preferably used, and the total light transmittance is preferably 85% or more. The total light transmittance 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 reflecting portion 53 shown in FIG. 3 is formed on the surface of the resin film 54 on the LED element 42 side, but is not limited thereto, and is formed on the surface opposite to the surface on the LED element 42 side. Alternatively, it may be formed on both surfaces of the resin film 54. The thickness of the reflective layer 55 is preferably 20 μm or more and 200 μm or less. The thickness of the reflective layer 55 can be measured by the same method as the thickness of the insulating protective film 45.

  The reflecting portion 53 preferably has a reflectance of at least 80% in the visible light wavelength region with a wavelength of 420 nm or more and 780 nm or less. The reflectance 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). Can be measured accurately. The value of the reflectance is a value obtained by measuring the relative reflectance with barium sulfate as the standard plate and the standard plate as 100%. The reflectance is an arithmetic average value of values obtained by measuring three times.

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

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

  As described above, the first optical sheet 50 shown in FIG. 3 includes the resin film 54 and the reflective layer 55 laminated on a part of at least one surface of the resin film 54. As shown in FIG. 5, the first optical sheet has a plurality of openings 135 penetrating in the thickness direction of the light reflective sheet 134 in a light reflective sheet 134 such as foamed polyethylene terephthalate (PET). The first optical sheet 130 may be used. Similar to the first optical sheet 50, the first optical sheet 130 includes a partition region 131, a transmission part 132, and a reflection part 133. The partition area 131, the transmission part 132, and the reflection part 133 in the first optical sheet 130 are the same as the partition area 51, the transmission part 52, and the reflection part 53 in the first optical sheet 50. Shall be omitted. Note that also in each partition region 131 of the first optical sheet 130, the aperture ratio, which is the area ratio of the transmission part 132, gradually increases from the central portion 131A of the partition region 131 toward the outer edge portion 131B of the partition region 131. It is preferable. In the case of the first optical sheet 130, the opening 135 functions as a transmission part 132 that transmits light, and a part other than the opening 135 in the first optical sheet 130 functions as a reflection part 133 that reflects light. . The openings 135 have an arbitrary shape (for example, a circular shape or a rectangular shape), and are dispersedly arranged so as not to be connected to each other along a predetermined pattern. The opening 135 can be formed by press punching 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. Further, the first spacer 60 has a function of holding a distance d1 from the surface 41A of the flexible wiring board 41 to the first optical sheet 50 at 0.6 mm or more and 6 mm or less.

  The first spacer 60 is made of a first resin. In the present specification, “consisting of resin” means that the resin is a main constituent. The Young's modulus at 25 ° C. of the first resin is preferably 1 GPa or more and 5 GPa or less. If the Young's modulus of the resin constituting the first spacer 60 is less than 1 GPa, the first spacer may not have sufficient strength to secure the flexible wiring board or the first optical sheet, and 5 GPa. If it exceeds, the first spacer may not be bent when the LED backlight device is installed on a curved surface or the like. The Young's modulus of the first resin was determined by conducting a tensile test at 25 ° C. using a dynamic viscoelasticity measuring device (product name “Rheogel-E4000”, manufactured by UBM). It is determined from the slope of the straight line portion of the stress-strain curve obtained by taking In addition, let the said Young's modulus be the arithmetic mean value of the value obtained by measuring 3 times. The lower limit of the Young's modulus at 25 ° C. of the resin constituting the first spacer 60 is more preferably 2 GPa or more, and the upper limit is more preferably 4 GPa or less.

  The first resin is not particularly limited as long as it has a Young's modulus greater than that of the second resin, as will be described later. However, the first resin is white based on the viewpoint of increasing the reflectance and guiding light to the first optical sheet 50. Resins are preferred. 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), poly Examples thereof include methyl 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.

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

  It is preferable that the first spacer 60 and the flexible wiring board 41 are fixed. A method for fixing the first spacer 60 and the flexible wiring board 41 is not particularly limited, and examples 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 flexible wiring board 41 are fixed via a double-sided tape 111. Specifically, the bottom surface 60A of the first spacer 60 (the bottom surface of a frame portion 61 and a crosspiece portion 63 described later) and the reflective layer 46 of the flexible wiring board 41 are fixed by being bonded via a double-sided tape 111. ing. By fixing the first spacer 60 and the flexible wiring board 41, the positional deviation of the first spacer 60 with respect to the LED element 42 can be further suppressed. The first spacer 60 and the flexible wiring board 41 may be fixed using an adhesive or an adhesive instead of the double-sided tape 111.

  The first spacer 60 and the first optical sheet 50 are preferably fixed. The 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 surfaces of a frame portion 61 and a crosspiece portion 63 described later) and the first optical sheet 50 are bonded via a double-sided tape 112. By fixing the 1st spacer 60 and the 1st optical sheet 50, position shift of the 1st optical sheet 50 with respect to the 1st spacer 60 and the LED element 42 can be suppressed more. In addition, the 1st spacer 60 and the 1st optical sheet 50 may be fixed using the adhesive agent or the adhesive instead of the double-sided tape 112. FIG.

  As shown in FIG. 6, the first spacer 60 includes a frame portion 61, a plurality of openings 62 positioned on the inner side of the frame portion 61, and a crosspiece 63 positioned between the openings 62. ing.

  The first spacer 60 shown in FIG. 6 has a lattice shape. The “lattice shape” in the present specification means a structure in which a plurality of openings formed by the frame portion and the crosspiece portion are arranged in a matrix shape 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 rectangular shape, an elliptical shape, and a circular shape. Examples of the quadrangular shape include a square shape, a rectangular shape, and a rhombus shape. In the first spacer 60 shown in FIG. 6, the rectangular openings 62 formed by the frame portion 61 and the crosspiece portion 63 are arranged in a matrix. Further, the corners of the frame part and / or the corners of the crosspieces may be curved in a plan view of the first spacer.

<Frame part and pier part>
The frame portion 61 shown in FIG. 6 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 61 is approximately the same size as the flexible wiring board 41.

  The crosspiece 63 partitions the openings 62 and is provided integrally with the frame 61. In the present specification, “provided integrally” means not only when there is no boundary between the frame portion and the crosspiece, that is, when the frame portion and the crosspiece are integrally formed, It is a concept including the case where is joined to the frame. In the first spacer 60, the frame portion 61 and the crosspiece portion 63 are integrally formed. Since the frame portion 61 and the crosspiece portion 63 are integrally formed, a first spacer without a joint can be obtained, and therefore, the assembly process of the LED backlight device is made rather than configuring the first spacer from a plurality of members. And the risk of displacement of the first optical sheet in the vibration test can be reduced. In addition, since there is no joint in the first spacer, there is no light entering the joint, and the optical loss can be reduced.

  As shown in FIG. 7, the crosspiece 63 is preferably disposed at a position corresponding to the boundary portion 51 </ b> C between the partition regions 51. 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. The crosspiece 63 is preferably molded integrally with the frame 61. FIG. 7 is a plan view of the first spacer 60 and the first optical sheet 50 from the LED element 42 side.

  As shown in FIG. 3, the side surfaces 61 </ b> A and 63 </ b> A facing the opening 62 of at least one of the frame part 61 and the crosspiece part 63 are opened from the flexible wiring board 41 toward the first optical sheet 50. It is preferable to incline so that the opening diameter of 62 becomes large. By forming the frame portion 61 and the crosspiece portion 63 having such side surfaces 61A and 63A, the light emitted from the LED element 62 is reflected by the side surface 61A of the frame portion 61 and the side surface 63A of the crosspiece portion 63, and the first Therefore, the light can be emitted from the LED backlight device 20 more efficiently. The 1st spacer 60 provided with the frame part 61 and the crosspiece 63 which have such side surfaces 61A and 63A can be obtained by injection molding, cutting, or a three-dimensional printer, for example. The side surfaces 61A and 63A may be curved in the cross section in the height direction of the first spacer 60, but are preferably linear from the viewpoint of ease of manufacture.

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

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

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

  The said convex part is for aligning the position of the 1st optical sheet which has several opening part which functions as a permeation | transmission part with respect to an LED element, and suppressing the position shift of this 1st optical sheet. The convex portion enters the opening that functions as the hole.

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

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

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

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

  The 1st spacer which has a convex part can be produced by injection molding. Further, it is possible to separately produce a convex part and fix the convex part to at least one of the frame part and the crosspiece part by an adhesive or the like or mechanical fixing. When fixed to the crosspiece, the convex portion may be peeled off from the frame portion and / or the crosspiece portion. Therefore, the convex portion and the frame portion and / or the crosspiece portion may be integrally formed by injection molding. preferable.

<Opening>
The opening 62 is for allowing the light from each LED element 42 to pass through, and penetrates in the height direction of the first spacer 60. A plurality of openings 62 are provided in the first spacer 60. The number of openings 62 is not particularly limited, but in FIG. 6, 4 vertical openings × 6 horizontal openings = 24 openings corresponding to the number of LED elements 42 (vertical 4 × horizontal 6 = 24). A portion 62 is formed.

  Since each opening 62 allows light from each LED element 42 to pass therethrough, each opening 62 has a size that allows the LED element 42 to enter the opening 62 when the first spacer 60 is viewed in plan view. It has become. In FIG. 7, one LED element 62 is disposed in one opening 62, but a plurality of LED elements may be disposed in one opening.

  The openings 62 shown in FIG. 6 are all the same size, but the openings 62 do not have to be the same size and may have different sizes.

  Although the first spacer 60 has a lattice shape, the first spacer may not have the lattice shape. For example, the first spacer may have a staggered arrangement of openings formed by the frame portion and the crosspiece portion. Specifically, the first spacer may have a honeycomb shape as shown in FIG. Similarly to the first spacer 60, the honeycomb-shaped first spacer 140 shown in FIG. 8 also has a frame portion 141, a plurality of openings 142 positioned on the inner side of the frame portion 141, and the openings 142. And has a crosspiece 143 provided integrally with the frame portion 141. Since the first spacer 140 is the same as the first spacer 60 except that it has a honeycomb shape, the description thereof is omitted here. In addition, when using the LED mounting board | substrate 40 in which the LED element 42 is arrange | positioned at matrix form, when using the grid | lattice-like 1st spacer 60 and using the LED mounting board by which LED element is arrange | positioned at zigzag form, A honeycomb-shaped first spacer 140 can be used.

<< second optical sheet >>
The second optical sheet 70 is a sheet having an optical function. As an optical sheet, if it is a sheet | seat which has an optical function, it will not specifically limit, For example, a light-diffusion sheet | seat, a lens sheet, or a reflection type polarization separation sheet etc. are mentioned. 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 0.5 mm or more and 5 mm or less. If the distance from the first optical sheet 50 to the second optical sheet 70 is less than 0.5 mm, the light diffusion function may not be sufficiently exhibited. If the distance exceeds 5 mm, the LED backlight device is thin. There is a risk that it will not be possible. 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 LED backlight device 20, the distance (OD) from the surface 41A of the flexible wiring board 41 to the second optical sheet 70 is preferably 1 mm or more and 10 mm or less. In this specification, the “distance from the surface of the flexible wiring board to the second optical sheet” means the distance from the surface of the flexible wiring board to the surface of the second optical sheet on the flexible 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 flexible 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 LED backlight device is thinned. May not be possible. The thickness of the second optical sheet 70 can be measured by the same method as the thickness of the first optical sheet 50.

  It is preferable that the 2nd optical sheet 70 is comprised from resin. 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 second spacer 80 is made of a second resin. The Young's modulus at 25 ° C. of the second resin constituting the second spacer 80 is 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 second resin constituting the second spacer 80 is measured by the same method as the Young's modulus at 25 ° C. of the first resin constituting the first spacer 60. .

  The difference between the Young's modulus of the first resin and the Young's modulus of the second resin (Young's modulus of the first resin−Young's modulus of the second resin) is preferably 0.05 GPa or more and 2 GPa or less. If this difference is 0.05 GPa or more, the second spacer 80 can be bent with a desired curvature when the LED backlight device 20 is installed on a curved surface, so that the damage of the second spacer 80 is further suppressed. In addition, if it is 2 GPa or less, the second spacer 80 can obtain a desired strength. The lower limit of this difference is more preferably 0.1 GPa or more, and the upper limit is more preferably 1 GPa or less.

  The Young's modulus of the second resin is preferably 0.5 GPa or more and 4 GPa or less. If the Young's modulus of the second resin is less than 0.5 GPa, the desired strength for fixing and supporting the second optical sheet may not be obtained, and if it exceeds 4 GPa, the LED backlight device There is a possibility that the second spacer cannot be bent when the is installed on a curved surface or the like. The lower limit of the Young's modulus of the second resin is more preferably 1 GPa or more, and the upper limit is more preferably 3 GPa or less.

  Among the second resins, a white resin is preferable from the viewpoint of increasing the reflectance and further guiding light to the second optical sheet 70. As the second resin, polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), acrylonitrile-butadiene-styrene copolymer resin (AES resin), poly Examples thereof include methyl methacrylate resin (PMMA resin), polyacetal resin, polyvinyl chloride resin, polyethylene resin, polypropylene resin, or a mixture of two or more of these resins. Among these, polycarbonate resin, ABS resin, ASA resin, AES resin, polyacetal resin, polyethylene resin, polypropylene resin, or a mixture of two or more of these resins is preferable from the viewpoints of heat resistance, moldability, and the like.

  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 70 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 areas becomes brighter than the portion corresponding to the outer edge portion, and if it exceeds 10 mm, the LED backlight device may not be thinned. In the present specification, the “height of the second spacer” refers to the height of the second spacer from the bottom surface of the second spacer in the direction perpendicular to the bottom surface, which is the 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 randomly measuring the height of the second spacer 80 at ten locations.

  As shown in FIG. 9, 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. 9 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> A 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> A of the first spacer 60 but also the outer peripheral surface 41 </ b> C of the flexible wiring board 41. Is arranged. That is, the LED mounting substrate 40, the first optical sheet 50, and the first spacer 60 are located inside the second spacer 80. Since the second spacer 80 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. Further, 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 constituted by a plurality of columnar bodies. Therefore, the heat of the second optical sheet 70 can be further radiated through the second spacer 80 when the LED backlight device 20 is used. 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 80 </ b> B of the second spacer 80 and the inner bottom surface 30 </ b> B of the housing 30.

  Also, the outer side surface 80C, which is the outer side surface of the second spacer 80 shown in FIG. 3, is in contact with the inner side surface 30D of the housing 30. In the present specification, the “outer surface of the second spacer” means a surface opposite to the inner surface that defines the opening of the second spacer. Further, in this specification, “the outer surface of the second spacer is in contact with the inner surface of the housing” is limited to the case where the outer surface of the second spacer is in direct contact with the inner surface of the housing. It 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 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 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. The 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 bottom surface 80 </ b> B of the second spacer 80 is fixed by bonding the opposite upper surface 80 </ b> D and the second optical sheet 70 with 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. In addition, the 2nd spacer 80 and the 2nd optical sheet 70 may be fixed using the adhesive agent or the adhesive instead of the double-sided tape 114. FIG.

  As shown in FIG. 3, the inner 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, the 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 more efficiently from the LED backlight device 20. The second spacer 80 having such an inner surface 80D 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.

<< 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. 10, 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 exit side, thereby enhancing the brightness 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 80 side (retroreflection function). As shown in FIG. 10, the lens sheet 90 includes a resin film 91 and a lens layer 92 provided on one surface of the resin film 91. The lens sheet 90 is arranged so that the lens layer 92 is positioned closer to the reflective polarization separation sheet 100 than the resin film 91.

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

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

  The unit lens 92A preferably has an apex angle θ of 80 ° or more and 100 ° or less, 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” available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarization separating sheet 63.

  When the frame-shaped second spacer is disposed so as to surround the outer peripheral surface of the first spacer, the second spacer is located outside the first spacer. Therefore, when the LED backlight device is bent, The amount of change of the second spacer is larger than the amount of change of the first spacer. For this reason, when the LED backlight device is bent, the second spacer is easier to crack than the first spacer. On the other hand, when the first spacer and the second spacer are made of a resin having a low Young's modulus, the rigidity of the LED backlight device is lowered. On the other hand, in the present embodiment, the frame-shaped second spacer 80 is disposed so as to surround the outer peripheral surface 60 </ b> A of the first spacer 60, but the second resin that constitutes the second spacer 80. Since the Young's modulus at 25 ° C. is smaller than the Young's modulus at 25 ° C. of the first resin constituting the first spacer 60, the second spacer 80 is more than the first spacer 60. But it is more flexible. Thereby, even when the LED backlight device 20 is bent, the second spacer 80 can be prevented from cracking, so that the LED backlight device can be bent while suppressing a decrease in rigidity of the LED backlight device. A light device 20 can be provided.

  As described above, usually, a plurality of columnar spacers are arranged between the wiring board and the optical sheet as spacers for separating the optical sheet from the wiring board. When the LED backlight device is bent, the distance between the wiring board and the optical sheet may change. In particular, when the optical sheet is a light-transmitting / reflecting sheet, the distance between the wiring board and the light-transmitting / reflecting sheet changes because the light-transmitting / reflecting sheet has patterns of transmitting portions and reflecting portions in each partition region. If this is the case, the in-plane uniformity of the brightness may be reduced. For this reason, even when the LED backlight device is bent, it is desirable to keep the distance between the wiring board and the optical sheet at a predetermined distance. On the other hand, since the first spacer 60 includes the frame portion 61 and the crosspiece 63 provided integrally with the frame portion 61, the first spacer 60 and the first optical sheet 50 are compared with the columnar spacer. The contact area can be increased. Thereby, even when the LED backlight device 20 is bent, the distance between the flexible wiring board 41 and the first optical sheet 50 can be maintained at a predetermined distance. Further, even when the LED backlight device 20 is bent by the first spacer 60, the distance between the flexible wiring board 41 and the first optical sheet 50, which is a light transmission / reflection sheet, is maintained at a predetermined distance. Therefore, the in-plane uniformity of luminance can be improved.

  Further, when a plurality of columnar spacers are used as a spacer for keeping the distance between the wiring board and the optical sheet at a predetermined distance, 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 60 includes the frame portion 61 and the crosspiece 63 provided integrally with the frame portion 61, so that compared to the columnar spacer, The contact area with the first optical sheet 50 can be increased. Thereby, the bending of the 1st optical sheet 50 can be suppressed. Further, since the first spacer 60 can suppress the bending of the first optical sheet 50 that is a light transmission / reflection sheet, the distance between the flexible wiring board 41 and the first optical sheet 50 is set to a predetermined distance. Can be maintained, and the in-plane uniformity of luminance can be improved.

  Currently, it is considered to mount an LED image display device on a vehicle. However, unlike a television, vibration is generated in the vehicle. For this reason, the LED backlight apparatus mounted in a vehicle needs to be able to endure a vibration test. However, when a vibration test is performed on the LED backlight device including the optical sheet and the columnar spacer, the optical sheet may be displaced with respect to the LED element. 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. On the other hand, according to the present embodiment, the first spacer 60 is fixed to the flexible wiring board 41 and the first optical sheet 50. Further, since the first spacer 60 includes the crosspiece 63 in addition to the frame 61, the first spacer 60 has higher rigidity than a columnar spacer or a simple frame spacer. For this reason, when the vibration test is performed on the LED backlight device 20, the swing width of the first optical sheet 50 is smaller than when a frame-shaped 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. In addition, since the first spacer 60 can suppress the displacement of the first optical sheet 50 that is a light transmitting and reflecting sheet with respect to the LED element 42, the in-plane uniformity of luminance can be improved. Further, since the first spacer 60 has higher rigidity than the columnar spacer, the first spacer 60 is not easily damaged even when a vibration test is performed.

  Applications of the LED image display device 10 and the LED backlight device 20 of the present embodiment are not particularly limited, but can be used for TV media, in-vehicle applications, advertising media applications such as signs, and the like. As described above, the LED backlight device mounted on the vehicle needs to be able to withstand the vibration test. However, according to the present embodiment, even if the vibration test is performed, the LED backlight device Since the position shift of the first optical sheet 50 with respect to the element 42 can be suppressed, the LED backlight device 20 can be suitably used for in-vehicle use.

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

<Example 1>
First, an LED mounting substrate was produced. Specifically, a copper layer having a thickness of 35 μm for wiring was laminated on one surface of a 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 part 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 penetrates in the height direction of the first spacer having a length of 111 mm × width of 290 mm, a width of 2 mm and a height of 2 mm, and a 20 mm × width of 22.4 mm inside the frame. It is provided with openings arranged in a matrix of 5 vertical x 12 horizontal, and crosspieces with a width of 2 mm and a height of 2 mm provided between the openings and provided integrally with the frame. there were.

  Furthermore, a second spacer was produced. The second spacer was produced by injection molding using a polypropylene resin. The second spacer has a frame portion of 117 mm in length × 310 mm in width, 2 mm in width, and 5 mm in height, and 1 penetrates in the height direction of the second spacer having a size of 113 mm in length × 306 mm in width inside the frame portion. 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 the above-mentioned first spacer is further formed 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 the 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 arranged to be the position of the pier. Further, the produced second spacer is disposed between the housing main body, the LED mounting substrate, and the first spacer, and the second spacer is attached to the bottom surface of the housing main body with a double-sided tape (product name “No. 5000NS”). ”, Manufactured by Nitto Denko Corporation). Furthermore, a light diffusion sheet having a length of 117 mm × width of 310 mm and a thickness of 1.5 mm was disposed on the second spacer. Finally, a frame-shaped lid having an opening with a size of 110 mm in length and 303 mm in width was fitted into the housing body to obtain an LED backlight 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 1>
In Comparative Example 1, an LED backlight device was obtained in the same manner as in Example 1 except that the second spacer was formed using polyacetal resin instead of polypropylene resin.

<Comparative example 2>
In Comparative Example 2, a plurality of columnar first spacers were used instead of the lattice-shaped first spacers, and the second spacers were formed using polyacetal resin instead of polypropylene resin. In the same manner as in Example 1, an LED backlight device was obtained. The first spacer used in Comparative Example 2 was a columnar one 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).

<Young's modulus measurement>
In the LED backlight devices according to Examples and Comparative Examples, Young's modulus at 25 ° C. of the resins of the first spacer and the second spacer was measured. The Young's modulus was measured using a dynamic viscoelasticity measuring device (product name “Rheogel-E4000”, manufactured by UBM) at 25 ° C., and the vertical axis was stressed and the horizontal axis was strained. It calculated | required from the inclination of the linear part of a stress-strain curve. In addition, the said Young's modulus was taken as the arithmetic mean value of the value obtained by measuring 3 times.

<Bending evaluation>
In the LED backlight devices according to the examples and comparative examples, a bending test was performed to evaluate whether or not the members constituting the LED backlight device were broken. The bending test was performed by bending the central portion of the LED backlight device with a curvature radius of 300 mm, with the short direction of the flexible wiring board being the axial direction of bending. The evaluation criteria were as follows.
A: The member constituting the LED backlight device was not broken.
X: The member which comprises an LED backlight apparatus was cracked.

<Bending evaluation>
In the LED backlight devices according to the examples and the comparative examples, it was visually evaluated whether or not the light transmission / reflection sheet was bent. The evaluation criteria were as follows. In addition, a bending shall be confirmed with the light transmission reflection sheet before the vibration test mentioned later.
○: Deflection was not confirmed in the light transmission reflection sheet.
X: Deflection was confirmed in the light transmission reflection sheet.

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

  The vibration test is performed on the vibration table of the single-axis electrodynamic vibration test apparatus (product name “EM2605S / H10”, manufactured by IMV), and the outer surface in the short direction of the housing of the LED backlight device is the vibration table side. In this state, the LED backlight device is fixed, and the LED backlight 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: It went by. 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. This vibration test is a vibration test required for an in-vehicle LED backlight device.

  The brightness distribution is 1 m away from the light emitting surface of the LED backlight device (the surface of the light diffusion sheet) in the normal direction of the light emitting surface in the 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).

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

The results are shown in Table 1.

  The results will be described below. In Comparative Example 1 and Comparative Example 2, the Young's modulus of the resin constituting the second spacer was larger than the Young's modulus of the resin constituting the first spacer. Therefore, when the LED backlight device was bent, Cracks were confirmed in the second spacer. On the other hand, in Example 1, since the Young's modulus of the resin constituting the second spacer was smaller than the Young's modulus of the resin constituting the first spacer, when the LED backlight device was bent, No cracks were observed in the second spacer or other members.

  In Comparative Example 2, since the first spacer was columnar, it was confirmed that the light transmission / reflection sheet was bent. On the other hand, in Example 1, since the 1st spacer was comprised from the frame part and the crosspiece, bending was not confirmed by the light transmissive reflective sheet. In Example 1, the in-plane uniformity of luminance before the vibration test was higher than that in Comparative Example 2. This is considered to be because in Example 1, the light transmission / reflection sheet was not bent.

  In Example 1, the lowering of the in-plane uniformity after the vibration test relative to the in-plane uniformity before the vibration test was suppressed as compared with Comparative Example 2. This is because the first spacer used in Example 1 is composed of a frame portion and a crosspiece portion, so that the rigidity is high, and the displacement of the light transmitting / reflecting sheet with respect to the LED element is almost equal even in a vibration test. It is thought that it did not happen.

DESCRIPTION OF SYMBOLS 10 ... LED image display apparatus 20 ... LED backlight apparatus 40 ... LED mounting board 41 ... Wiring board 42 ... LED element 50, 130 ... 1st optical sheet 50A ... Outer peripheral surface 51, 131 ... Partition area 51A, 131A ... Center part 51B, 131B ... outer edge portions 52, 132 ... transmission portions 53, 133 ... reflection portions 60, 140 ... first spacer 60A ... outer peripheral surfaces 61, 141 ... frame portions 62, 142 ... openings 63, 143 ... crosspiece portions 70 ... Second optical sheet 80 ... second spacer

Claims (6)

An LED mounting board comprising a flexible wiring board and a plurality of LED elements mounted on one surface of the flexible wiring board;
A first optical sheet disposed to face the plurality of LED elements;
A second optical sheet disposed on the light exit side of the first optical sheet;
A first spacer disposed between the flexible wiring board and the first optical sheet, made of a first resin, and separating the first optical sheet from the LED mounting board;
It arrange | positions so that the outer peripheral surface of a said 1st optical sheet and the outer peripheral surface of a 1st spacer may be comprised, it is comprised from 2nd resin, and the said 2nd optical sheet is spaced apart with respect to the said 1st optical sheet A frame-shaped second spacer,
The LED backlight device, wherein a Young's modulus of the second resin constituting the second spacer is smaller than a Young's modulus of the first resin constituting the first spacer.   The first spacer is fixed to the flexible wiring board and the first optical sheet, the first spacer is positioned inside the frame portion and the frame portion, and the first spacer A plurality of openings that penetrate in the height direction and allow light from each of the LED elements to pass therethrough, and a crosspiece that is positioned between the openings and is provided integrally with the frame. Item 2. The LED backlight device according to Item 1.   The LED backlight device according to claim 2, wherein the first spacer has a lattice shape or a honeycomb shape.   The LED backlight device according to claim 2, wherein a thickness of the second optical sheet is larger than a thickness of the first optical sheet.   The first optical sheet includes a partition region divided into a plurality of parts in plan view, and each partition region includes a plurality of transmission portions that transmit a part of light from the LED element, and the LED element. A plurality of reflecting portions that reflect a part of the light, and an aperture ratio that is an area ratio of the transmitting portion in each partition region gradually increases from a central portion of the partition region toward an outer edge portion of the partition region. The LED backlight device according to any one of claims 1 to 4. LED backlight device according to any one of claims 1 to 5,
An LED image display device comprising: a display panel disposed closer to an observer than the LED backlight device.

Images