JP2018106971A - LED backlight device and LED image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED backlight device in which a spacer is hardly broken and which can suppress positional deviation of a first optical sheet and a second optical sheet, and to provide an LED display device.SOLUTION: An LED backlight device 20 includes: an LED mounting substrate including a plurality of LED elements 42 mounted on one surface 41A of a wiring board 41; a first optical sheet 50 arranged so as to oppose to the LED elements 42; a second optical sheet 60 arranged on a light emission side of it; and a spacer including a first spacer part 71 for separating the first optical sheet 50 with respect to the LED mounting substrate, and a frame-like second spacer part 72 for surrounding an outer peripheral surface 50A of the first optical sheet 50, and for separating the second optical sheet 60 with respect to the first optical sheet 50. The first spacer part 71 is located on the inner side of the second spacer part 72, and the first spacer part 71 is provided integrally with the second spacer part 72.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 LED mounting 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 first spacers for separating the light transmitting / reflecting sheet from the LED mounting substrate are arranged, and separately from the first spacer, light diffusion is performed on the light transmitting / reflecting sheet. A plurality of columnar second spacers for separating the sheets are arranged.

JP 2010-272245 A

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

  However, when the columnar first spacer and the second spacer as described above are used, when an impact is applied to the LED backlight device due to vibrations of the automobile or train or for some reason, the first spacer and There is a possibility that the second spacer may be damaged.

  In addition, some optical sheets, such as a light transmitting / reflecting sheet, require the alignment between the LED element and the optical sheet, but since no countermeasures have been taken at present, When the columnar first spacer and the second spacer are used, even if the alignment between the LED element and the optical sheet is accurately performed, the impact is caused by vibrations of the automobile or the train or some other factor. Is added to the LED backlight device, the position of the optical sheet with respect to the LED element is shifted, so-called positional shift occurs, and the in-plane luminance uniformity may be reduced.

  The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide an LED backlight device that can prevent the spacers from being damaged and that can suppress displacement of the first optical sheet and the second optical sheet, and an LED display device including the LED backlight device.

  According to one aspect of the present invention, a wiring board, an LED mounting board including a plurality of LED elements mounted on one surface of the wiring board, and a first board disposed to face the plurality of LED elements. 1 optical sheet, a second optical sheet disposed on the light emitting side of the first optical sheet, and disposed between the wiring substrate and the first optical sheet, and the wiring substrate and the first optical sheet. A first spacer that is fixed to the first optical sheet and that separates the first optical sheet from the LED mounting substrate; and an outer peripheral surface of the first optical sheet that surrounds the first spacer. And a spacer having a frame-shaped second spacer portion that separates the second optical sheet from the first optical sheet, and the first spacer portion is positioned inside the second spacer portion. And said Wherein the first spacer portions are provided integrally with the second spacer portions, LED backlight device is provided.

  The said LED backlight apparatus WHEREIN: You may have a clearance gap between the outer peripheral surface of a said 1st optical sheet, and the inner surface of a said 2nd spacer part.

  The LED backlight device further includes a housing having an inner bottom surface and an inner surface rising from the inner bottom surface, wherein the LED mounting substrate, the first optical sheet, the second optical sheet, and the spacer are Disposed in the housing, the bottom surface of the second spacer portion is in contact with the inner bottom surface of the housing, and there is a gap between the inner surface of the housing and the outer surface of the second spacer portion. You may do it.

  In the LED backlight device, the first spacer portion is positioned along the circumferential direction of the inner side surface of the second spacer portion, and is located on the inner side of the frame portion. A plurality of openings penetrating in the height direction of one spacer and allowing light from each of the LED elements to pass through; and a crosspiece located between the openings and provided integrally with the frame portion You may have.

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

  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 aspect of the present invention, it is possible to provide an LED backlight device that is less likely to break the spacer and that can suppress displacement of the first optical sheet and the second optical sheet. 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 spacer shown by FIG. It is a top view which shows the arrangement | positioning relationship between the 1st optical sheet and spacer which are shown by FIG. It is a top view of the other spacer which concerns on embodiment. It is a partial expanded sectional view of the other LED backlight apparatus which concerns on embodiment. It is a partial expanded sectional view of the other LED backlight apparatus which concerns on embodiment. 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. FIG. 4 is a plan view of the first optical sheet shown in FIG. 1, and FIG. 5 is a plan view of another first optical sheet according to the embodiment. FIG. 6 is a plan view of the spacer shown in FIG. 1, and FIG. 7 is a plan view showing the positional relationship between the first optical sheet and the spacer shown in FIG. 8 is a plan view of another spacer according to the embodiment, FIGS. 9 and 10 are enlarged sectional views of a part of another LED backlight device according to the embodiment, and FIG. 11 is shown in FIG. It is sectional drawing of a lens sheet.

<<<<< LED image display device >>>>
The LED image display device 10 shown in FIGS. 1 and 2 includes a direct-type LED backlight device 20 and a display panel 110 disposed on the viewer side of the LED backlight device 20.

<<< Display Panel >>>
A display panel 110 shown in FIG. 1 and FIG. 2 is a liquid crystal display panel, and includes a polarizing plate 111 disposed on the light incident side, a polarizing plate 112 disposed on the light exit side, a polarizing plate 111 and a polarizing plate 112. And a liquid crystal cell 113 disposed between them. As the polarizing plates 111 and 112 and the liquid crystal cell 113, known polarizing plates and liquid crystal cells can be used.

<<< LED backlight device >>>
The LED backlight device 20 shown in FIGS. 1 and 2 includes a housing 30, an LED mounting substrate 40, a first optical sheet 50, a second optical sheet 60, and a spacer 70. In addition, the LED backlight device 20 includes a lens sheet 80 and a reflective polarization separation sheet 90 laminated on the second optical sheet 60. The LED backlight device 20 only needs to include the LED mounting substrate 40, the first optical sheet 50, the second optical sheet 60, and the spacer 70, and the housing 30, the lens sheet 80, or the reflective polarized light. The separation sheet 90 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, when the LED backlight device 20 is used for in-vehicle use, the total thickness of the LED backlight device 20 is preferably 15 mm or less, and more preferably 10 mm or less. 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 90A of the reflective polarization separation sheet 90.

<< Case >>
The housing 30 accommodates at least the LED mounting substrate 40, the first optical sheet 50, the second optical sheet 60, and the spacer 70. In the present embodiment, the housing 30 houses a lens sheet 80 and a reflective polarization separation sheet 90 in addition to the LED mounting substrate 40 and the like.

  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.

<< LED mounting board >>
The LED mounting substrate 40 includes a wiring substrate 41 and a plurality of LED elements 42 mounted on one surface (hereinafter referred to as “surface”) 41 </ b> A of the wiring substrate 41. As shown in FIG. 2, the LED mounting substrate 40 has a surface 41 </ b> B opposite to the front surface 41 </ b> A on which the LED elements 42 are mounted on the wiring substrate 41 (hereinafter, this surface is referred to as “back surface”) 41 </ b> B. It is arrange | positioned in the housing | casing 30 so that it may be located in the inner bottom face 30B side.

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

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

  The wiring board 41 may be a rigid wiring board, but is preferably a flexible wiring board. Since the wiring board 41 is a flexible wiring board, a bendable LED backlight device can be obtained. A wiring board 41 shown in FIG. 3 is a flexible wiring board. “Flexible” means that there is flexibility, and “flexible wiring board” means a wiring board that is generally flexible and can be bent. The term “flexibility” in this specification means bending so that the radius of curvature is at least 1 m. The flexible wiring board is bent so that the radius of curvature is preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, and particularly preferably 5 cm.

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

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

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

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

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

  The thickness of the resin film 43 is not particularly limited, but is generally 10 μm or more and 500 μm or less from the viewpoint of not being a bottleneck as a heat dissipation path, having heat resistance and insulation, and a balance of manufacturing costs. It is preferable that Moreover, it is preferable that it is the said thickness range also from a viewpoint of maintaining favorable productivity at the time of manufacturing by a roll-to-roll system. The thickness of the resin film 43 is 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 wiring substrate 41, the surface of one surface of the resin film 43 is preferably 80% or more, more preferably 90%, and most preferably 95% or more is covered with the metal wiring part 44. preferable. Accordingly, the LED elements 42 can be arranged with high density, and the excessive heat generated can be sufficiently diffused quickly through the metal wiring portion 44 and radiated to the outside via the resin film 43. Therefore, the LED 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 wiring substrate 41 and is not particularly limited, but may be 10 μm or more and 50 μm or less as an example. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 44 is preferably 10 μm or more. In addition, if the thickness of the metal wiring portion is less than 10 μm, the influence of heat shrinkage of the resin film 43 is large, and warpage after the processing is likely to increase during the solder reflow processing. The thickness is preferably 10 μm or more. On the other hand, when the thickness of the metal wiring portion is 50 μm or less, it is possible to maintain sufficient flexibility of the wiring substrate, and it is possible to prevent a decrease in handling properties due to an increase in weight. The thickness of the metal wiring portion 44 can be measured by the same method as that for the resin film 43.

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

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

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

  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 wiring board 41 so as to cover the region excluding the LED element mounting region 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. There is a risk of warping of the wiring board provided with. In order to prevent such warpage, it is preferable to provide a metal foil on the surface of the resin film 43 opposite to the surface on the metal wiring portion 44 side. Further, by providing such a metal foil, the heat of the LED mounting substrate 40 at the time of lighting can be further radiated to the housing body 31.

<< LED element >>
The LED element 42 is a light emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. As LED elements, there are known a structure in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element, and a structure in which both the P-type and N-type electrodes are provided on one side of the element. An LED element can also be used for the LED 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 wiring board 41. The “matrix shape” in this specification means a state in which the matrix is two-dimensionally arranged. In the present embodiment, the LED elements 42 are arranged in a matrix, but the arrangement state of the LED elements is not particularly limited. For example, the LED elements may be arranged in a staggered manner. A plurality of LED elements 42 are mounted on the wiring board 41. The number of LED elements 42 mounted on the wiring board 41 is not particularly limited as long as it is plural. The arrangement density of the LED elements 42 is preferably 0.02 pieces / cm ² or more and 2.0 pieces / cm ² or less, and preferably 0.1 pieces / cm ² or more and 1.5 pieces / cm ² or less. More preferred.

<< first optical sheet >>
The first optical sheet 50 is a sheet having an optical function. Examples of the first optical sheet 50 include a light transmission / reflection sheet and the like. 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 on the LED mounting substrate 40, and the first optical sheet 50 is formed by a first spacer portion 71 described later of the spacer 70. It is separated from the LED mounting substrate 40. The first optical sheet 50 is disposed substantially parallel to the wiring board 41.

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

  The thickness of the first optical sheet 50 is preferably 25 μm or more and 1 μm or less. If the thickness of the first optical sheet is less than 25 μm, the 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.

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

  As shown in FIG. 4, the first optical sheet 50 is disposed so that the central portion 51A of each partition region 51 is a region corresponding to each LED element 42, so that the central portion is more central than the outer edge portion 51B. The amount of light incident on 51A increases. For this reason, in each partition area 51, it is preferable that the aperture ratio, which is the area ratio of the transmission part 52, gradually increases from the central part 51A toward the outer edge part 51B. By gradually increasing the aperture ratio in each partition region 51 from the central portion 51A toward the outer edge portion 51B, it is possible to further improve the uniformity of luminance on the light emitting surface while securing a sufficient amount of light. 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 cells having the same area in one partition region is arbitrary. For example, it is desirable to set so that the number of transmission parts 72 existing in each cell is approximately equal. In addition, the “aperture ratio” defines a plurality of concentric circles centered on the center point of one partition region at equal intervals from the central region to the outer region located outside the central region. You may obtain | require by calculating the area ratio of the permeation | transmission part in each area | region between circumference | surroundings similarly to the above. According to this calculation method, the above “opening ratio” can be defined also for a partitioned area other than a general opening arrangement in which rectangular openings are arranged in a grid pattern. In each partition region 51, the aperture ratio only needs to gradually increase from the central portion 51A toward the outer edge portion 51B. For example, the aperture ratio is constant in a limited partial range near the central portion or the outer edge portion. An area may exist.

  In the central portion 51A of each partition region 51, the area ratio is preferably 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 65 can be formed by pattern-printing the thermosetting resin composition on the surface of the resin film 64 using 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.

<< second optical sheet >>
The second optical sheet 60 is a sheet having an optical function. The second optical sheet is not particularly limited as long as it is a sheet having an optical function, and examples thereof include a light diffusion sheet, a lens sheet, and a reflective polarization separation sheet. The second optical sheet 60 shown in FIGS. 1 and 2 is a light diffusion sheet. By disposing the second optical sheet 60 which is a light diffusion sheet, the light transmitted through the first optical sheet 50 can be further diffused by the second optical sheet 60, 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 80 may not be provided. When the second optical sheet is a reflection-type polarization separation sheet, the reflection-type polarization separation sheet. 90 need 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 80 or the reflection type polarization separation sheet 90 can be used.

  The second optical sheet 60 is disposed on the light emission side of the first optical sheet 50. The second optical sheet 60 is separated from the first optical sheet 50 by a second spacer portion 72 described later of the spacer 70. The second optical sheet 60 is disposed substantially parallel to the first optical sheet 50.

  The distance d2 from the first optical sheet 50 to the second optical sheet 60 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 60 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 60 is an arithmetic average value of values obtained by measuring this distance at 10 random locations.

  In addition, the distance (OD) from the surface 41A of the wiring board 41 to the second optical sheet 60 is preferably 1 mm or more and 10 mm or less from the viewpoint of reducing the thickness of the LED backlight device. The “distance from the surface of the wiring board to the second optical sheet” in this specification means the distance from the surface of the wiring board to the surface of the second optical sheet on the wiring board side. The distance from the surface 41 </ b> A of the wiring board 41 to the second optical sheet 60 is an arithmetic average value of values obtained by measuring this distance at 10 random locations. The upper limit of the distance from the surface 41A of the wiring board 41 to the second optical sheet 60 is preferably 5 mm or less.

  The thickness of the second optical sheet 60 is preferably larger than the thickness of the first optical sheet 50. When the thickness of the second optical sheet 60 is larger than the thickness of the first optical sheet 50, the second optical sheet 60 is less likely to bend than the first optical sheet 50. For this reason, the second optical sheet 60 can hold the distance between the first optical sheet 50 and the second optical sheet 60 at a predetermined distance by the frame-shaped second spacer portion 72. .

  The thickness of the second optical sheet 60 is preferably 0.3 mm or more and 5 mm or less. This is because if the thickness of the second optical sheet 60 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 60 can be measured by the same method as the thickness of the first optical sheet 50.

  It is preferable that the 2nd optical sheet 60 is comprised from resin. In the present specification, “consisting of resin” means that the resin is a main constituent. The second optical sheet 60 is formed of a translucent resin film made of polycarbonate resin, acrylic resin, or the like, and one surface side of the resin film, and is made of resin. And a lens layer having a random lens array or the like.

<< Spacer >>
The spacer 70 is for separating the first optical sheet 50 from the LED mounting substrate 40 and separating the second optical sheet 60 from the first optical sheet 50.

  As shown in FIG. 6, the spacer 70 includes a first spacer portion 71 that separates the first optical sheet 50 from the LED mounting substrate 40, and a second optical sheet 60 that separates the first optical sheet 50. And a frame-shaped second spacer portion 72 to be separated. The first spacer portion 71 is located inside the second spacer portion 72 and is located between the LED mounting substrate 40 and the first optical sheet 50. The first spacer portion 71 is provided integrally with the second spacer portion 72. In this specification, “the first spacer portion is provided integrally with the second spacer portion” is only when there is no boundary between the first spacer portion and the second spacer portion. In addition, the case where the first spacer portion is bonded to the second spacer portion is also included. Such a spacer 70 can be produced by, for example, injection molding, punching, cutting, or a three-dimensional printer (3D printer).

  The spacer 70 is preferably made of a resin from the viewpoint of easy molding and protecting the first optical sheet 50 and the like from impact. Among the resins, a white resin is preferable from the viewpoint of increasing the reflectivity and further guiding light to the first optical sheet 50 and the second optical sheet 60.

  The Young's modulus at 25 ° C. of the resin constituting the spacer 70 is preferably 0.5 GPa or more and 5 GPa or less. If the Young's modulus of the resin is less than 0.5 GPa, the first spacer portion may not be able to secure the strength for fixing the first spacer portion to the wiring board or the first optical sheet. If it exceeds 5 GPa, the spacer may not be bent when the LED backlight device is installed on a curved surface or the like. Moreover, if it is 5 GPa or more, since the spacer 70 has favorable cushioning properties, it is possible to suppress cracking of the first optical sheet 50 and the like during a vibration test described later. The lower limit of the Young's modulus at 25 ° C. of the resin is more preferably 1 GPa or more, and the upper limit is further preferably 4 GPa or less. The Young's modulus of the above resin at 25 ° C. was determined by conducting a tensile test at 25 ° C. using a dynamic viscoelasticity measuring device (product name “Rheogel-E4000”, manufactured by UBM Co., Ltd.). The strain is obtained from the slope of the straight line portion of the stress-strain curve obtained by taking the strain. In addition, let the said Young's modulus be the arithmetic mean value of the value obtained by measuring 3 times.

  Examples of the resin include polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), acrylonitrile-butadiene-styrene copolymer resin (AES resin), polymethyl methacrylate. Examples thereof include a resin (PMMA resin), a polyacetal resin, a polyvinyl chloride resin, a polyethylene resin, a polypropylene resin, or a mixture obtained by mixing two or more of these resins. Among these, polycarbonate resin, ABS resin, ASA resin, AES resin, or a mixture of two or more of these resins is preferable from the viewpoint of heat resistance, moldability, and the like.

<First spacer part>
As described above, the first spacer portion 71 is for separating the first optical sheet 50 from the LED mounting substrate 40. The first spacer portion 71 has a function of holding the distance d1 from the surface 41A of the wiring board 41 to the first optical sheet 50 at 0.6 mm or more and 6 mm or less.

  The height h1 of the first spacer portion 71 shown in FIG. 3 is preferably not less than 0.5 mm and not more than 5 mm. If the height of the first spacer portion is less than 0.5 mm, the distance between the LED element and the first optical sheet is too short, so that the central portion of each partition region of the first optical sheet is more than the outer edge portion. May become brighter, and if it exceeds 5 mm, the LED backlight device may not be thinned. In the present specification, “the height of the first spacer portion” refers to the first spacer portion from the bottom surface of the first spacer portion in the direction perpendicular to the bottom surface that is the surface on the wiring board side of the first spacer portion. It means the distance to the upper surface which is the surface opposite to the bottom surface. The height h1 of the first spacer portion 71 is an arithmetic average value of values obtained by randomly measuring the height of the first spacer portion 71 at ten locations.

  The first spacer portion 71 and the wiring board 41 are fixed. The method for fixing the first spacer portion 71 and the 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 portion 71 and the wiring substrate 41 are fixed via a double-sided tape 101. Specifically, the bottom surface 71A of the first spacer portion 71 (the bottom surface of a frame portion 73 and a crosspiece portion 75 described later) and the reflective layer 46 of the wiring board 41 are fixed by being bonded via a double-sided tape 101. ing. By fixing the first spacer portion 71 and the wiring board 41, the positional deviation of the spacer 70 with respect to the LED element 42 can be suppressed. In addition, the 1st spacer part 71 and the wiring board 41 may be fixed using the adhesive agent or the adhesive instead of the double-sided tape 101. FIG.

  The first spacer portion 71 and the first optical sheet 50 are fixed. A method for fixing the first spacer portion 71 and the first optical sheet 50 is not particularly limited, and examples include fixing by adhesion or mechanical fixing means. In FIG. 3, the first spacer portion 71 and the first optical sheet 50 are fixed by being bonded via a double-sided tape 102. Specifically, the upper surface 71B of the first spacer portion 71 (upper surfaces of a frame portion 73 and a crosspiece 75 described later) and the first optical sheet 50 are bonded via a double-sided tape 102. By fixing the first spacer 71 and the first optical sheet 50, the positional deviation of the first optical sheet 50 with respect to the first spacer portion 71 and the LED element 42 can be further suppressed. In addition, the 1st spacer part 71 and the 1st optical sheet 50 may be fixed using the adhesive agent or the adhesive instead of the double-sided tape 102. FIG.

  As shown in FIG. 6, the first spacer portion 71 includes a frame portion 73 provided along the circumferential direction of the inner side surface 72 </ b> A of the second spacer portion 72, and a plurality of first spacer portions 71 located on the inner side of the frame portion 73. , And a crosspiece 75 located between the openings 74 and provided integrally with the frame 73.

  The first spacer portion 71 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 in the plan view of the first spacer portion. Examples of the shape of the opening in a plan view of the first spacer portion include a polygonal shape such as a quadrangular 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 portion 71 shown in FIG. 6, rectangular openings 74 formed by the frame portion 73 and the crosspiece 75 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 part.

(Frame and pier)
The frame portion 73 shown in FIG. 6 has a quadrangular shape in plan view, but the shape of the frame portion can be changed as appropriate according to the shape of the LED mounting substrate and the like. The frame portion 73 is approximately the same size as the wiring substrate 41.

  The crosspiece 75 divides the openings 74 and is provided integrally with the frame 75. In this specification, “the crosspiece is provided integrally with the frame” means that there is no boundary between the frame and the crosspiece, that is, the frame and the crosspiece are integrally formed. It is a concept including not only the case where the crosspiece is joined to the frame. In the first spacer portion 71, the frame portion 73 and the crosspiece 75 are integrally formed. By integrally forming the frame portion 73 and the crosspiece portion 75, it is possible to obtain a first spacer portion without a joint, so that the LED backlight device of the LED backlight device can be obtained rather than configuring the first spacer portion from a plurality of members. It is possible to simplify the assembly process and reduce the risk of displacement of the first optical sheet in the vibration test. Further, since there is no joint in the first spacer portion, there is no light entering the joint, and the optical loss can be reduced.

  As shown in FIG. 7, the crosspiece 75 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. FIG. 7 is a plan view of the spacer 70 and the first optical sheet 50 from the LED element 42 side.

  As shown in FIG. 3, the side surfaces 73 </ b> A and 75 </ b> A facing the opening 74 of at least one of the frame portion 73 and the crosspiece 75 are open toward the first optical sheet 50 from the wiring board 41. It is preferable to incline so that the opening diameter of this may become large. By forming the frame portion 73 and the crosspiece portion 75 having such side surfaces 73A and 75A, the emitted light from the LED element 42 is reflected by the side surface 73A of the frame portion 73 and the side surface 75A of the crosspiece portion 75, so that the first Therefore, the light can be emitted from the LED backlight device 20 more efficiently. The spacer 70 having such side surfaces 73A and 75A can be obtained by, for example, injection molding, cutting, or a three-dimensional printer. The side surfaces 73A and 75A may be curved in the cross section in the height direction of the first spacer 71, 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 spacer can be produced by injection molding, punching, cutting, or a three-dimensional printer. However, when the first spacer portion is provided with a convex portion, among these, the convex portion From the viewpoint of ease of formation, injection molding is preferred.

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

  When using the 1st optical sheet 130 which has the 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 convex portions may be formed as the entire first spacer portion, but a plurality of convex portions 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, the convex portions are formed in at least four places so that a quadrangle is drawn by the convex portions in plan view of the first spacer portion. preferable.

  The spacer including the first spacer portion having the convex portion can be manufactured 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 are preferably integrally formed by injection molding. .

<Opening>
The opening 74 is for allowing light from each LED element 42 to pass through, and penetrates in the height direction of the first spacer portion 71. A plurality of openings 74 are provided in the first spacer portion 71. The number of openings 74 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 74 is formed.

  Since each opening 74 allows light from each LED element 42 to pass therethrough, each opening 74 is large enough to allow the LED element 42 to enter the opening 74 when the first spacer 71 is viewed in plan. It has become. In FIG. 8, one LED element 42 is disposed in one opening 74, but a plurality of LED elements may be disposed in one opening.

  The openings 74 shown in FIG. 7 are all the same size, but the openings 74 do not have to be the same size and may be different sizes.

  Although the first spacer portion 71 has a lattice shape, the first spacer portion 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, as shown in FIG. 8, the first spacer portion may have a honeycomb shape in which hexagonal openings are arranged in a staggered manner in a plan view. The spacer 140 shown in FIG. 8 includes a first spacer portion 141 and a frame-shaped second spacer portion 142, as with the spacer 70. The first spacer portion 141 is located inside the second spacer portion 142 and is located between the LED mounting substrate 40 and the first optical sheet 50. The first spacer portion 141 is provided integrally with the second spacer portion 142. Similar to the first spacer portion 71, the first spacer portion 141 is located between the frame portion 143, the plurality of openings 144 positioned on the inner side of the frame portion 143, and the opening portion 144. And a crosspiece 144 provided integrally therewith. Since the first spacer 141 is the same as the first spacer portion 71 except for the honeycomb shape, the description thereof is omitted here. In addition, the second spacer portion 142 is the same as the second spacer portion 72, and therefore the description thereof is omitted here. When the LED mounting substrate 40 in which the LED elements 42 are arranged in a matrix is used, the LED mounting substrate in which the LED elements are arranged in a staggered manner using the spacer 70 having the grid-like first spacer portions 71. Can be used, the spacer 140 having the honeycomb-shaped first spacer portion 141 can be used.

<Second spacer part>
The second spacer portion 72 is for separating the second optical sheet 60 from the first optical sheet 50 as described above. The second spacer portion 72 holds the distance d2 from the first optical sheet 50 to the second optical sheet 60 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 holding the distance to the sheet 60 at 1 mm or more and 10 mm or less.

  The height h2 of the second spacer portion 72 shown in FIG. 3 is higher than the height h1 of the first spacer portion 71. The height h2 of the second spacer portion 72 shown in FIG. 3 is preferably 1 mm or more and 10 mm or less. If the height of the second spacer portion is less than 1 mm, the distance between the first optical sheet and the second optical sheet is too short, so the portion corresponding to the LED element 42 in the second optical sheet is There is a possibility that it will become brighter than other parts, 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 second spacer portion from the bottom surface of the second spacer portion in the direction perpendicular to the bottom surface that is the surface on the inner bottom surface side of the housing. It means the distance to the upper surface of the spacer part. The height h2 of the second spacer portion 72 is an arithmetic average value of values obtained by randomly measuring the height of the second spacer portion 72 at ten locations.

  The second spacer portion 72 has a frame shape. The “frame shape” in the present specification is not limited to a structure in which one round is connected without a break, but may have a gap in the middle as long as it is generally connected. As shown in FIG. 2, the second spacer portion 72 is disposed so as to surround the outer peripheral surface 50 </ b> A of the first optical sheet 50. As shown in FIG. 2, the second spacer portion 72 is disposed so as to surround not only the outer peripheral surface 50 </ b> A of the first optical sheet 50 but also the outer peripheral surface 41 </ b> C of the wiring substrate 41. That is, the LED mounting substrate 40, the first optical sheet 50, and the first spacer portion 71 are located inside the second spacer portion 72. Since the second spacer portion 72 has a frame shape, the light transmitted through the first optical sheet 50 and directed toward the second spacer portion 72 is reflected by the second spacer portion 72, The second optical sheet 60 can be guided. Further, since the second spacer portion 72 has a frame shape, the contact area with the second optical sheet 60 can be increased as compared with the case where the second spacer is constituted by a plurality of columnar bodies. Therefore, when the LED backlight device 20 is used, the heat of the second optical sheet 60 can be further dissipated through the second spacer portion 72. In addition, since the second spacer portion 72 has a frame shape, the second spacer portion 72 and the second optical sheet 60 are more than in the case where the second spacer portion is constituted by a plurality of columnar bodies. Therefore, the second optical sheet 60 is less likely to be misaligned.

  As shown in FIG. 3, the bottom surface 72 </ b> B of the second spacer portion 72 is preferably in contact with the inner bottom surface 30 </ b> B of the housing 30. In the present specification, the “bottom surface of the second spacer portion” means a surface on the inner bottom surface side of the housing in the second spacer portion. Further, in this specification, “the bottom surface of the second spacer portion is in contact with the inner bottom surface of the housing” is limited to the case where the bottom surface of the second spacer portion is in direct contact with the inner bottom surface of the housing. It is a concept that includes a case where a layer that can be ignored in terms of heat conduction, such as a double-sided tape, an adhesive, or an adhesive, is interposed between the bottom surface of the second spacer portion and the inner bottom surface of the housing. is there. In FIG. 3, a double-sided tape 103 described later is interposed between the bottom surface 72 </ b> B of the second spacer portion 72 and the inner bottom surface 30 </ b> B of the housing 30.

  In addition, an outer side surface 72 </ b> C that is an outer side surface of the second spacer portion 72 shown in FIG. 3 is in contact with the inner side surface 30 </ b> D of the housing 30. In the present specification, the “outer surface of the second spacer portion” means a surface opposite to the inner surface that defines the opening of the second spacer portion. Further, in this specification, “the outer surface of the second spacer portion is in contact with the inner surface of the housing” means that the outer surface of the second spacer portion is in direct contact with the inner surface of the housing. In addition, there may be a case in which 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 portion and the inner surface of the housing. It is a concept that includes. In FIG. 3, the outer side surface 72 </ b> C of the second spacer portion 72 is in direct contact with the inner side surface 30 </ b> D of the housing 30.

  The second spacer portion 72 and the housing 30 are preferably fixed from the viewpoint of further suppressing the displacement of the second optical sheet 60 with respect to the LED element 42. The method for fixing the second spacer portion 72 and the housing 30 is not particularly limited, and examples include fixing by adhesion or mechanical fixing means. In FIG. 3, the bottom surface 72 </ b> B of the second spacer portion 72 and the inner bottom surface 30 </ b> B of the housing 30 are fixed by being bonded via a double-sided tape 103. Here, since the second spacer portion 72 has a frame shape, the bonding area with the housing 30 can be increased as compared with the case where the second spacer portion is constituted by a plurality of columnar bodies. As a result, the second spacer portion 72 can be easily fixed. The second spacer portion 72 and the housing 30 may be bonded via an adhesive or an adhesive instead of the double-sided tape 103.

  The second spacer portion 72 and the second optical sheet 60 may be fixed. A method for fixing the second spacer portion 72 and the second optical sheet 60 is not particularly limited, and examples thereof include fixing by adhesion or mechanical fixing means. In FIG. 3, the upper surface 72 </ b> D opposite to the bottom surface 72 </ b> B in the second spacer portion 72 and the second optical sheet 60 are fixed by being bonded via a double-sided tape 104. By fixing the second spacer portion 72 and the second optical sheet 60, the positional deviation of the second optical sheet 60 with respect to the LED element 42 can be further suppressed. In addition, the 2nd spacer part 72 and the 2nd optical sheet 60 may be fixed using the adhesive agent or the adhesive instead of the double-sided tape 104. FIG.

  As shown in FIG. 3, the region on the second optical sheet 60 side from the first optical sheet 50 in the inner side surface 72 </ b> A of the second spacer portion 72 is from the first optical sheet 50 to the second optical sheet. It is preferable to incline toward the sheet 60 so that the opening diameter of the opening 72E increases. By forming the second spacer portion 72 having such an inner surface 72A, the light from the LED element 42 is reflected by the inner surface 72A of the second spacer portion 72 and guided to the second optical sheet 60. Therefore, light can be emitted from the LED backlight device 20 more efficiently. The spacer 70 including the second spacer portion 72 having such an inner surface 72A can be obtained by, for example, injection molding, punching, cutting, or a three-dimensional printer. The inner side surface 72A may be curved in the cross section in the height direction of the second spacer portion 72, but is preferably linear from the viewpoint of ease of manufacture.

  In FIG. 3, the outer peripheral surface 51C of the first optical sheet 50 and the outer peripheral surface 41C of the wiring board 41 are in contact with the inner side surface 72A of the second spacer portion 72, but as shown in FIG. A gap 105 may be provided between the inner side surface 72 </ b> A of the second spacer portion 72 and the outer peripheral surface 51 </ b> C of the first optical sheet 50. A gap 106 may also be provided between the inner side surface 72A of the second spacer portion 72 and the outer peripheral surface 41C of the wiring board 41. By having such gaps 105 and 106, the LED backlight device 20 is subjected to an impact in a direction perpendicular to the normal direction of the surface 41A of the wiring board 41 for some reason, and the first optical sheet 50 and the wiring Even if the substrate 41 slightly moves toward the second spacer 72, the gap 105 can suppress the collision between the second spacer portion 72 and the first optical sheet 50, and the gap 106 allows the second spacer Since the collision between the portion 72 and the wiring board 41 can be suppressed, damage to the wiring board 41, the first optical sheet 50, and the spacer 70 can be further suppressed.

  The distance between the inner surface 72A of the second spacer portion 72 and the outer peripheral surface 51C of the first optical sheet 50 and the distance between the inner surface 72A of the second spacer portion 72 and the wiring board 41, that is, the gap 105 , 106 are each preferably 0.1 mm or more and 10 mm or less. If this distance is less than 0.1 mm, the second backlight portion and the first spacer portion are affected when an impact is applied to the LED backlight device in a direction perpendicular to the normal direction of the surface of the wiring board for some reason. There is a possibility that the collision with the optical sheet or the wiring board cannot be suppressed, and if it exceeds 10 mm, the LED backlight device may not be miniaturized.

  In FIG. 3, the outer side surface 72C of the second spacer portion 72 is in contact with the inner side surface 30D of the housing 30, but as shown in FIG. A gap 107 may be provided between the inner surface 30 </ b> D of the body 30. By having such a gap 107, when an impact is applied to the LED backlight device 20 in a direction perpendicular to the normal direction of the surface 41A of the wiring board 41 for some reason, the second gap is caused by the presence of the gap 107. Since the spacer portion 72 is slightly bent toward the inner surface 30D side of the housing 30, even if the first optical sheet 50 is slightly moved toward the second spacer 72 due to an impact, the second spacer portion 72 and the first spacer Damage to the first optical sheet 50 and the spacer 70 due to the collision of the optical sheet 50 can be further suppressed. Note that the gap 107 shown in FIG. 10 gradually widens from the inner bottom surface 30 </ b> B of the housing 30 toward the second optical sheet 60. That is, the outer side surface 72 </ b> C of the second spacer portion 72 is inclined toward the inner side of the second spacer portion 72 from the bottom surface 72 </ b> B of the second spacer portion 72 toward the upper surface 72 </ b> C.

  The distance between the outer side surface 72C of the second spacer portion 72 and the inner side surface 30D of the housing 30, that is, the width of the gap 107 is preferably 0.1 mm or more and 10 mm or less at the largest portion. If this distance is less than 0.1 mm, the second spacer portion is effective when an impact is applied to the LED backlight device in a direction perpendicular to the normal direction of the surface of the wiring board for some reason. There is a possibility that it cannot be bent, and if it exceeds 10 mm, the LED backlight device may not be miniaturized.

<< Lens sheet >>
The lens sheet 80 has a function of changing the traveling direction of incident light and emitting it from the light exit side. As shown in FIG. 11, the lens sheet 80 changes the traveling direction of light having a large incident angle, such as L1, for example, and emits it from the light-emitting side to intensively improve the luminance in the front direction (collection). In addition to the light function, for example, the light having a small incident angle such as L2 is reflected and returned to the second optical sheet 80 side (retroreflection function). As shown in FIG. 11, the lens sheet 80 includes a resin film 81 and a lens layer 92 provided on one surface of the resin film 81. The lens sheet 80 is arranged so that the lens layer 82 is positioned closer to the reflective polarization separation sheet 90 than the resin film 91.

(Resin film)
As a constituent material of the resin film 81, for example, polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethyl Examples of the thermoplastic resin include pentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane.

(Lens layer)
The lens layer 82 includes a plurality of unit lenses 82A arranged side by side on the light output side. The unit lens 82A 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 82A 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 90 transmits only the first linearly polarized light component (for example, P-polarized light) out of the light emitted from the lens sheet 80 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 90 is reflected again and the polarized light is canceled (including both the first linearly polarized light component and the second linearly polarized light component), The light again enters the reflective polarization separation sheet 90.

  As the reflective polarization separation sheet 90, “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.

  According to the present embodiment, the first spacer portion 71 that separates the first optical sheet 50 from the LED mounting substrate 40 is a frame that separates the second optical sheet 60 from the first optical sheet 50. Since the second spacer portion 72 is integrally provided, the rigid spacer 70 can be obtained. Thereby, even if an impact is applied to the LED backlight device 20 due to vibration of a car or a train or any other factor, the breakage of the spacer 70 can be suppressed. Even if the vibration or impact is applied to the LED backlight device 20, the swing width of the first optical sheet 50 or the second optical sheet 60 is smaller than when the columnar spacer is used. The positional deviation between the first optical sheet 50 and the second optical sheet 60 can be suppressed.

  Furthermore, according to this embodiment, since the first spacer portion 71 includes the crosspiece 75 provided integrally with the frame portion 73 in addition to the frame portion 73, the frame is used as the first spacer portion. Rigidity is high even when using the shape. For this reason, when the vibration test is performed on the LED backlight device 20, the swing width of the first optical sheet 50 can be further reduced. The positional deviation of the first optical sheet 50 can be further suppressed. In addition, since the first spacer portion 71 can further 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 further improved. it can.

  Further, when a plurality of columnar spacers are used as the spacers, when the optical sheet is thin, the optical sheet may be bent between the adjacent spacers. 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 portion 71 includes the frame portion 73 and the crosspiece 75 provided integrally with the frame portion 73, so that it is compared with 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. Moreover, since the 1st spacer part 71 can suppress the bending of the 1st optical sheet 50 which is a light transmissive reflection sheet, the distance of the wiring board 41 and the 1st optical sheet 50 is made into predetermined distance. Can be maintained, and the in-plane uniformity of luminance can be improved.

  According to the present embodiment, the second spacer portion 72 has a frame shape, the bottom surface 72B of the second spacer portion 72 is in contact with the inner bottom surface 30B of the housing 30, and the second spacer portion 72 Since the outer side surface 72C is in contact with the inner side surface 30D of the housing 30, it is possible to increase the contact area with the housing 30 and the contact area with the second optical sheet 60 as compared with the columnar spacer. The area can be increased. Thereby, the curvature of the 2nd optical sheet 60 can be suppressed.

  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. The LED backlight device mounted on the automobile is particularly required to be able to withstand the vibration test. However, according to the present embodiment, the spacer 70 is damaged even when the vibration test is performed. Moreover, since the position shift of the 1st optical sheet 50 and the 2nd optical sheet 60 with respect to the LED element 42 can be suppressed, the LED backlight apparatus 20 can be used suitably for vehicle-mounted 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 film 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 × 12 in width were mounted on the copper wiring portion of the flexible wiring board through 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 spacer was produced. The spacer was produced by injection molding using a polycarbonate resin. The spacer has a first spacer portion and a second spacer portion formed integrally with the first spacer portion. The first spacer portion has a lattice shape, and is a rectangular frame portion having a length of 111 mm × width of 290 mm, a width of 2 mm and a height of 2 mm, and a first 20 mm × width of 22.4 mm inside the frame portion. A total of 60 openings arranged in a matrix of 5 vertical x 12 horizontal penetrating in the height direction of the spacer portion, a width of 2 mm provided integrally with the frame portion, located between the openings, and And a crosspiece having a height of 2 mm. Further, the second spacer portion has a frame shape, and the first spacer portion is located inside the second spacer portion. The second spacer portion has an outer dimension of 117 mm long × 310 mm wide, an inner dimension of 111 mm × 290 mm, and a height of 5 mm. The height from the bottom surface of the second spacer portion to the bottom surface of the first spacer portion. The thickness was 0.2 mm.

  And the produced LED mounting board | substrate was arrange | positioned so that an LED element might become the 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 bottom surface of the first spacer portion of the manufactured spacer is attached to the surface of the flexible wiring board in the LED mounting substrate, and the bottom surface of the second spacer portion of the spacer is attached to the inner bottom surface of the housing body (product name “ No. 5000NS ", manufactured by Nitto Denko Corporation). Furthermore, the light-transmitting / reflecting sheet prepared above was fixed to the upper surface of the first spacer portion via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation). Here, the first spacer portion is arranged so that light from each LED element passes through the opening of the first spacer portion, and the light transmitting / reflecting sheet has a boundary portion between the divided regions as the first portion. It was arrange | positioned so that it might become the position of the crosspiece of a spacer. Further, 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 portion. Finally, a casing was formed by fitting a frame-shaped lid having an opening with a size of 110 mm in length and 303 mm in width into the casing body, and an LED backlight device was obtained. 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 a plurality of columnar first spacers and columnar second spacers were used instead of the spacers. The first spacer and the second spacer used in Comparative Example 1 were columnar with a diameter of 5 mm and a height of 2 mm made of polycarbonate resin. The first spacers were arranged between the wiring board and the light transmitting / reflecting sheet and between the LED elements one by one. One second spacer is disposed between the inner bottom surface of the housing and the light diffusion sheet, and one spacer is disposed at each of the four corners of the housing. The columnar first spacer portion is fixed to the flexible wiring substrate and the light reflecting / transmitting sheet via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation), and the columnar second spacer portion is It was fixed to the inner bottom surface of the casing body via a double-sided tape (product name “No. 5000NS”, manufactured by Nitto Denko Corporation).

<Appearance evaluation>
In the LED backlight devices according to Examples and Comparative Examples, the appearance of the spacer after the vibration test was visually observed and evaluated. The vibration test is performed on the vibration table of the single-axis electrodynamic vibration test device (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. The evaluation results were based on the following criteria.
○: In the spacer, breakage such as breakage or breakage was not confirmed.
X: In the spacer, breakage such as breakage or breakage was confirmed.

<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 was performed under the same test conditions as the vibration test described in the column of the appearance evaluation. 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).

<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. In addition, bending shall be confirmed with the light transmission reflection sheet before a vibration test.
◯: No bending was confirmed in the light transmission / reflection sheet.
X: Deflection was confirmed in the light transmission reflection sheet.

The results are shown in Table 1.

  The results will be described below. In Comparative Example 1, a first spacer that separates the light transmission / reflection sheet from the LED mounting substrate and a second spacer that separates the light diffusion sheet from the light transmission / reflection sheet are separately provided, and Since the first spacer and the second spacer were columnar, the rigidity of the first spacer and the second spacer was low, and damage was confirmed in the first spacer and the second spacer.

  In Comparative Example 1, the in-plane uniformity of the luminance after the vibration test was clearly lower than the in-plane uniformity of the luminance before the vibration test. This is probably because the first spacer was columnar, so that the rigidity was low, and the light transmission / reflection sheet was displaced from the LED element by the vibration test.

  Furthermore, in Comparative Example 1, bending was confirmed in the light transmission / reflection sheet. In Comparative Example 1, the in-plane uniformity of luminance before the vibration test was low. This is presumably because the light transmission / reflection sheet was bent.

  On the other hand, in Example 1, the 1st spacer part which spaces apart a light transmission reflection sheet with respect to a LED mounting substrate, and the 2nd spacer which spaces apart a light diffusion sheet with respect to a light transmission reflection sheet are united. Therefore, the spacer was high in rigidity and no damage was confirmed in the spacer.

  Moreover, in Example 1, the fall of the in-plane uniformity after the vibration test with respect to the in-plane uniformity before the vibration test was suppressed as compared with Comparative Example 1. This is because the spacer in which the first spacer portion and the second spacer portion are integrally formed is used, so that the rigidity of the spacer is high, and the position of the light transmitting / reflecting sheet relative to the LED element is also determined by a vibration test. This is thought to be because there was almost no deviation.

  Furthermore, in Example 1, since the 1st spacer part was comprised from the frame part and the crosspiece, the bending was not confirmed by the light transmissive reflection sheet. In Example 1, the in-plane uniformity of luminance before the vibration test was high. This is considered because the light transmission reflection sheet was not bent.

DESCRIPTION OF SYMBOLS 10 ... LED image display apparatus 20 ... LED backlight apparatus 30 ... Housing | casing 30B ... Inner bottom surface 30D ... Inner side surface 40 ... LED mounting board 41 ... Wiring board 41A ... Front surface 41B ... Back surface 41C ... Outer peripheral surface 42 ... LED element 50,130 ... first optical sheet 50A ... peripheral surfaces 51, 131 ... partition areas 51A, 131A ... center parts 51B, 131B ... outer edge parts 52, 132 ... transmission parts 53, 133 ... reflection parts 60 ... second optical sheets 70, 140 ... spacers 71 and 141 ... first spacer parts 72 and 142 ... second spacer parts 73 and 143 ... frame parts 74 and 144 ... openings 75 and 145 ... crosspieces

Claims (7)

An LED mounting board comprising a wiring board and a plurality of LED elements mounted on one surface of the wiring board;
A first optical sheet disposed to face the plurality of LED elements;
A second optical sheet disposed on the light exit side of the first optical sheet;
The first optical sheet is disposed between the wiring board and the first optical sheet, is fixed to the wiring board and the first optical sheet, and separates the first optical sheet from the LED mounting board. A spacer having a spacer portion and a frame-shaped second spacer portion that is disposed so as to surround an outer peripheral surface of the first optical sheet and that separates the second optical sheet from the first optical sheet. And comprising
The LED backlight, wherein the first spacer portion is located inside the second spacer portion, and the first spacer portion is provided integrally with the second spacer portion. apparatus.   The LED backlight device according to claim 1, wherein a gap is provided between an outer peripheral surface of the first optical sheet and an inner surface of the second spacer portion.   A housing having an inner bottom surface and an inner surface rising from the inner bottom surface, wherein the LED mounting substrate, the first optical sheet, the second optical sheet, and the spacer are disposed in the housing; The bottom surface of the second spacer portion is in contact with the inner bottom surface of the housing, and there is a gap between the inner surface of the housing and the outer surface of the second spacer portion. The LED backlight device described.   The first spacer portion is positioned along the circumferential direction of the inner side surface of the second spacer portion, and is located on the inner side of the frame portion, and the height direction of the first spacer And a plurality of openings that allow light from each of the LED elements to pass therethrough, and a crosspiece that is provided between the openings and is provided integrally with the frame. LED backlight apparatus as described in any one of these.   The LED backlight device according to claim 4, wherein the first spacer portion has a lattice shape or a honeycomb shape.   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 3 to 5. The LED backlight device according to any one of claims 1 to 6,
An LED image display device comprising: a display panel disposed closer to an observer than the LED backlight device.

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