WO2019221304A1 - Planar illumination device and liquid crystal display device - Google Patents

Planar illumination device and liquid crystal display device Download PDF

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Publication number
WO2019221304A1
WO2019221304A1 PCT/JP2019/019954 JP2019019954W WO2019221304A1 WO 2019221304 A1 WO2019221304 A1 WO 2019221304A1 JP 2019019954 W JP2019019954 W JP 2019019954W WO 2019221304 A1 WO2019221304 A1 WO 2019221304A1
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WO
WIPO (PCT)
Prior art keywords
light
light source
illumination device
planar illumination
light guide
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PCT/JP2019/019954
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French (fr)
Japanese (ja)
Inventor
直良 山田
浩史 遠山
隆 米本
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富士フイルム株式会社
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Publication of WO2019221304A1 publication Critical patent/WO2019221304A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S2/00—Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/30—Elements containing photoluminescent material distinct from or spaced from the light source
    • F21V9/32—Elements containing photoluminescent material distinct from or spaced from the light source characterised by the arrangement of the photoluminescent material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements

Definitions

  • the present disclosure relates to a planar illumination device and a liquid crystal display device including the planar illumination device.
  • Liquid crystal display devices have low power consumption and are increasingly used year by year as space-saving image display devices.
  • the liquid crystal display device has a configuration in which a backlight unit, a backlight side polarizing plate, a liquid crystal panel, a viewing side polarizing plate, and the like are provided in this order.
  • the backlight unit includes, for example, an edge light type (side) that includes a light guide plate and a light source disposed on an end surface thereof, guides light incident on the end surface from the light source, and irradiates the liquid crystal panel from the entire main surface.
  • an edge light type (side) that includes a light guide plate and a light source disposed on an end surface thereof, guides light incident on the end surface from the light source, and irradiates the liquid crystal panel from the entire main surface.
  • There is also a direct type that irradiates the liquid crystal panel from the entire main surface of the light diffusing plate provided on the light source without using the light guide plate and arranging the light source directly under the liquid crystal panel. are known.
  • HDR High Dynamic Range
  • HDR is a display technology that improves the contrast (brightness / darkness ratio) between the bright and dark parts of an image
  • HDR in an LCD usually uses a direct-type backlight unit in which a plurality of point light sources are arranged in a plane. This is realized by performing local dimming that partially turns on / off.
  • the existing type has a thickness of 15 mm or more.
  • a light diffusing plate is usually used for the purpose of diffusing light from a point light source and reducing unevenness of brightness (unevenness of in-plane brightness) in the plane of outgoing light.
  • unevenness of brightness unevenness of in-plane brightness
  • LED Light Emitting Diode
  • the LED light source has strong directivity, unless a sufficient distance is provided between the light diffusing plate and the LED light source, the portion directly above the LED becomes very bright and significant luminance unevenness occurs. For this reason, it is difficult to reduce the thickness of the direct type backlight unit.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2010-277086 (hereinafter referred to as Patent Document 1) includes a plurality of light guide layers on an LED light source, and by providing irregularities at the interface of the light guide layer, the light from the light source is emitted.
  • Patent Document 2 Japanese Patent Laid-Open No. 2010-80280 discloses a light guide plate in which one surface is a light emission surface and a plurality of recesses are provided on the surface opposite to the emission surface.
  • a surface light source device is proposed that includes at least two light emitting elements (point light sources) that are stored in each of the recesses, emit light in a direction in which the light guide plate extends, and are arranged in different directions. ing.
  • Patent Document 1 it is difficult for the technique of Patent Document 1 to make the light emitted from the light source incident sufficiently efficiently on each light guide layer, thereby suppressing luminance unevenness and using light. Efficiency improvement cannot be realized sufficiently.
  • the distance between the light source and the light guide plate can be arranged close to each other.
  • uniform light emission can be performed.
  • a white LED is used as a point light source provided in the planar illumination device.
  • white LED what laminated
  • a white LED is provided with a phosphor layer, it has a size of about 1 mm. Therefore, if a white LED is used, the thickness cannot be sufficiently reduced.
  • an object of the present disclosure is to provide a planar illumination device capable of emitting illumination light that is thin, uniform, and has less luminance unevenness, and a liquid crystal display device including the planar illumination device. To do.
  • a light guide having a light extraction mechanism that reflects, refracts, or scatters light guided inside, one plate having a plurality of recesses and an emission surface that emits light.
  • a light source unit having a plurality of point light sources each of which is accommodated in each of the plurality of recesses, each of the plurality of recesses being perpendicular to the exit surface and from the point light source And a reflecting surface that faces the point light source and reflects the light from the point light source, and each of the plurality of recesses is formed between the reflecting surface and the point light source.
  • a planar illuminating device including a phosphor disposed between and a point light source.
  • ⁇ 2> The planar illumination device according to ⁇ 1>, wherein the phosphor includes at least a phosphor that emits green light and a phosphor that emits red light.
  • ⁇ 3> The planar illumination device according to ⁇ 1> or ⁇ 2>, wherein the phosphor includes quantum dots.
  • ⁇ 4> The planar illumination device according to any one of ⁇ 1> to ⁇ 3>, wherein the point light source is a near ultraviolet light emitting diode or a blue light emitting diode.
  • ⁇ 5> The planar illumination device according to any one of ⁇ 1> to ⁇ 4>, wherein each of the plurality of point light sources emits light toward the reflection surface of each recess.
  • ⁇ 6> The planar illumination device according to any one of ⁇ 1> to ⁇ 5>, wherein the incident surface is a cylindrical surface.
  • ⁇ 7> The planar illumination device according to any one of ⁇ 1> to ⁇ 6>, wherein the reflection surface is made of a metal thin film.
  • the metal thin film contains at least silver.
  • ⁇ 9> The planar illumination device according to any one of ⁇ 1> to ⁇ 6>, wherein the reflection surface is made of a dielectric multilayer film.
  • ⁇ 10> The planar illumination device according to any one of ⁇ 1> to ⁇ 9>, wherein the reflective surface has a convex shape toward one surface as it approaches the center of the reflective surface.
  • a liquid crystal display device comprising a liquid crystal display element and the planar illumination device according to any one of ⁇ 1> to ⁇ 1>.
  • planar illumination device that emits illumination light that has a thin shape, is uniform, and has less luminance unevenness
  • liquid crystal display device that includes the planar illumination device
  • FIG. 3 is a schematic cross-sectional view showing a part of the liquid crystal display device of Example 1.
  • FIG. 6 is a schematic cross-sectional view showing a part of the liquid crystal display device of Example 4.
  • FIG. 10 is a schematic cross-sectional view showing a part of the liquid crystal display device of Comparative Example 2.
  • FIG. 10 is a schematic cross-sectional view showing a part of the liquid crystal display device of Comparative Example 3.
  • FIG. 10 is a schematic cross-sectional view showing a part of a liquid crystal display device of Comparative Example 4.
  • FIG. 1 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device 1 according to an embodiment of the present disclosure.
  • the liquid crystal display device 1 includes a liquid crystal display element 50 on which a backlight is incident from a backlight incident surface opposite to the image display surface, and a backlight unit 2 disposed on the backlight incident surface side of the liquid crystal display element 50.
  • the liquid crystal display element 50 includes a liquid crystal panel, a viewing side polarizing plate provided on the viewing side thereof, and a backlight side polarizing plate provided on the backlight side.
  • the backlight unit 2 is an embodiment of the planar illumination device of the present disclosure.
  • the backlight unit 2 is a light source unit 10 including a plurality of point light sources 14 arranged two-dimensionally, a surface 20a including a plurality of recesses 30, and a surface facing the surface 20a, and an emission surface that emits light. And a light guide 20 having 20b.
  • the light guide 20 is a plate-like member having a light extraction mechanism 40 that reflects, refracts, or scatters light guided inside.
  • Each of the plurality of recesses 30 is perpendicular to the exit surface 20b, faces the incident surface 31 through which light from the point light source 14 enters the light guide 20, the point light source 14, and a point.
  • a reflecting surface 33a that reflects light from the light source 14;
  • each of the plurality of recesses 30 includes a phosphor disposed separately from the point light source 14 between the reflecting surface 33 a and the point light source 14.
  • the light from the point light source 14 enters the light guide 20 either directly on the incident surface 31 of the recess 30 or after being reflected by the reflecting surface 33 a. At least a part of the light incident on the light guide 20 spreads in the in-plane direction within the light guide 20 and is extracted from the emission surface 20 b by the action of the light extraction mechanism 40. As a result, light with uniform in-plane luminance is emitted from the emission surface 20b.
  • a backlight with high in-plane uniformity emitted from the backlight unit 2 including the light guide 20 can be incident on the liquid crystal display element 50.
  • the backlight unit 2 includes the light guide 20 and can emit light with uniform brightness, a thick space between the light source unit 10 and the light guide 20 is not necessary. Therefore, it can be made very thin as compared with the conventional case although it is a direct type backlight. Further, since the backlight unit 2 is a direct type, multi-division local dimming as many as the number of point light sources provided is possible.
  • the overall thickness of the liquid crystal display device 1 can be reduced. Furthermore, since local dimming is possible, a thin liquid crystal display device capable of HDR display can be realized.
  • the backlight unit 2 may include a prism sheet, a diffusion sheet, a brightness enhancement sheet, and the like (not shown) between the light guide 20 and the liquid crystal display element 50.
  • the light source unit 10 the light guide 20, and the light uniforming action by the light guide 20 will be described in detail.
  • the light source unit 10 includes a plurality of point light sources 14 arranged corresponding to the plurality of concave portions 30 of the light guide 20 and a reflector 12 on which the plurality of point light sources 14 are arranged.
  • FIG. 2 is a schematic plan view of the light source unit 10. As shown in FIG. 2, in the present embodiment, the point light sources 14 are evenly arranged at predetermined intervals on the reflector 12 in the vertical and horizontal directions. In the planar illumination device of the present disclosure, the arrangement of the point light sources is not limited to the case where the arrangement of the point light sources is evenly arranged at predetermined intervals in the vertical and horizontal directions.
  • the point light source 14 is a light source capable of exciting a phosphor described later provided in the concave portion 30 of the light guide 20, and is, for example, a monochromatic light source that emits near ultraviolet or blue light.
  • a light emitting diode or a laser diode can be used.
  • a laser light source is preferable in that the color reproducibility is improved and the light can be spread more efficiently in the in-plane direction.
  • a vertical cavity surface emitting laser (VCSEL) is preferable from the viewpoint of reducing the thickness of the light source.
  • the point light source is preferably arranged so as to emit light toward the reflecting surface 33a of the recess 30 which is arranged to face the point light source.
  • the number of point light sources 14 is directly linked to the number of area divisions for local dimming. In order to increase the number of area divisions, it is necessary to increase the number of point light sources. By using a point light source having a smaller size, the number of point light sources to be arranged can be increased. As such a point light source 14, an LED having one side of 300 ⁇ m or less, preferably 200 ⁇ m or less is suitable.
  • the reflection plate 12 is not particularly limited, and various known ones can be used. In order to use light efficiently, it is preferable to have a reflecting surface with low absorption and high reflectance.
  • a multilayer film using white PET (polyethylene terephthalate) or a polyester resin can be used.
  • white PET include MCPET (registered trademark) manufactured by Furukawa Electric Co., Ltd.
  • 3SR ESR brand name
  • positioned is not restricted to a reflecting plate. However, in order to further improve the light utilization efficiency by further reflecting the light reflected by the light guide 20 or the prism sheet among the light emitted from the point light source 14 toward the light guide 20, the point light source 14 is preferably disposed on the reflector 12.
  • the reflection plate 12 may cover the surface of the substrate excluding a portion where the point light source 14 is disposed in the light source unit 10.
  • the thickness of the reflecting plate 12 is preferably thinner than that of the point light source, and may be formed as a thin coating film on the surface of the substrate on which the point light source 14 is mounted, for example.
  • the reflective coating film is obtained, for example, by applying white ink or the like to the surface of the substrate.
  • the light guide 20 is a planar member that equalizes the luminance of the light from the light source unit 10 incident on the one surface 20a and emits the light from the light emitting surface 20b.
  • FIG. 3 is a schematic plan view (upper view) and a schematic cross-sectional view taken along line III-III (lower view) of a part of the backlight unit 2 shown in FIG.
  • the arrangement and size of the light extraction mechanism 40 in the lower diagram do not match those in the upper diagram.
  • the constituent material of the light guide 20 is not particularly limited, and various known plate-like materials (sheet-like materials) can be used.
  • acrylic resin such as polyethylene terephthalate, polypropylene, polycarbonate, polymethyl methacrylate, benzyl methacrylate, MS resin (polymethacryl styrene), cycloolefin polymer, cycloolefin copolymer, cellulose acylate such as cellulose diacetate and cellulose triacetate, etc.
  • the light guide sheet formed with resin with high transparency similar to the light guide plate used for a well-known backlight apparatus is mentioned.
  • the resin is not limited to a thermoplastic resin, and may be, for example, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin, or a thermosetting resin.
  • the light guide 20 may be formed of a transparent inorganic material such as glass or quartz. Since the glass is less deformed by applying heat, humidity, or force than the resin, the light guide 20 can be installed so that the position of the light incident portion 30 corresponds to the position of the point light source 14. It becomes easy.
  • the thickness of the light guide 20 is preferably 100 ⁇ m to 2000 ⁇ m, and more preferably 200 ⁇ m to 1000 ⁇ m.
  • the concave portion 30 functions as an incident portion for allowing the light from the point light source 14 to enter the light guide 20.
  • the concave portion 30 is a concave portion having an opening on one surface 20a, and is composed of a side wall surface functioning as the above-described incident surface 31 (hereinafter also referred to as the side wall surface 31) and a bottom surface 32.
  • the light guide 20 has the one surface 20 a side on the light source unit 10 side, and each recess 30 is installed so as to cover each point light source 14, and the bottom surface 32 of each recess 30 faces the point light source 14. Accordingly, at least a part of each of the plurality of point light sources 14 of the light source unit 10 is accommodated in each of the plurality of recesses 30.
  • the side wall surface 31 of the recess 30, that is, the incident surface 31 for allowing the light emitted from the point light source 14 to enter the light guide 20 is a surface perpendicular to the emission surface 20 b.
  • the bottom surface 32 of the recess 30 is covered with a reflection layer 33, and the reflection layer 33 constitutes a reflection surface 33 a that reflects light emitted from the point light source 14. That is, the concave portion 30 is perpendicular to the emission surface 20 a, faces the point light source 14 with the incident surface 31 through which light from the point light source 14 enters the light guide 20, and the point light source 14. And a reflection surface 33a for reflecting the light from the.
  • the concave portion 30 may be referred to as the incident portion 30.
  • the recess 30 is installed so that the diameter of the opening is larger than the size of the point light source 14 and covers the point light source 14.
  • the point light source 14 is large enough to be included in the opening. Preferably, it is 200 ⁇ m to 2000 ⁇ m.
  • the recess 30 can be produced by imprinting using a mold, injection molding, or the like.
  • the surface of a flat plate made of acrylic or the like can be produced by drilling so as not to penetrate through mechanical cutting or laser processing.
  • a through hole is made in a flat plate of acrylic or the like by machining or laser processing, and a resin or the like is embedded in one surface of the hole, or a thin film of acrylic or the like is bonded to one surface to close the hole.
  • Each of the plurality of recesses 30 of the light guide 20 has a layer 60 containing a phosphor inside the recess 30.
  • a layer 60 containing phosphor hereinafter referred to as “phosphor layer 60” is disposed between the reflecting surface 33 a and the point light source 14 so as to be separated from the point light source 14.
  • any phosphor that converts near ultraviolet light or blue light into blue light, green light, red light, or yellow light can be used.
  • YAG yttrium aluminum garnet
  • ⁇ -sialon phosphor a CaAlSiN 3 : EU (CASN) phosphor
  • KSF K 2 SiF 6 : Mn 4+
  • quantum dots or quantum rods can be used.
  • a quantum dot or a quantum rod a core-shell type semiconductor nanoparticle is preferable from a viewpoint of improving durability.
  • the core II-VI semiconductor nanoparticles, III-V semiconductor nanoparticles, multi-component semiconductor nanoparticles, and the like can be used.
  • CdSe, CdTe, InP, InGaP, and CuInS 2 are preferable from the viewpoint of emitting visible light with high efficiency.
  • the shell CdS, ZnS, ZnO, GaAs, and a composite thereof can be used, but the shell is not limited thereto.
  • Quantum dots or quantum rods have an advantage that the phosphor layer can be made thin because they have high absorbance.
  • quantum dots or quantum rods can obtain an arbitrary emission wavelength by adjusting at least one of the composition and the particle size, high luminance and high color reproducibility are combined with the emission wavelength of a point light source. It is easy to adjust so that
  • the point light source 14 can be a monochromatic light source.
  • white light or other desired emission color can be obtained by converting the wavelength of light emitted from the monochromatic light source with a phosphor.
  • a white LED generally used for constituting a white light source is obtained by laminating a phosphor layer on a blue monochromatic light source and has a size of about 1 mm. .
  • a monochromatic light source such as a monochromatic light emitting diode has a light source of several ⁇ m to several hundred ⁇ m, it can be made thinner than a planar illumination device using a white LED.
  • a monochromatic light source is used as a point light source, a phosphor sheet containing a phosphor is disposed on the light exit surface side of the light guide 20, and a wavelength of a part of near ultraviolet light or blue light is wavelength-converted. It is also conceivable to obtain white light. However, even if the light source portion can be thinned by using a monochromatic light source, it cannot be sufficiently thinned by using a phosphor sheet. On the other hand, as described above, by providing the phosphor layer 60 in the concave portion 30 of the light guide 20, a monochromatic light source can be used and it is not necessary to provide a phosphor sheet. Thinning can be realized. Moreover, the usage-amount of fluorescent substance can be reduced compared with the case where a fluorescent substance sheet is used.
  • Quantum dots and quantum rods can obtain high color reproducibility compared with the case of using a YAG phosphor or the like.
  • quantum dots and quantum rods have low heat resistance, and durability is lowered when they are placed in contact with a point light source.
  • the phosphor layer 60 is disposed apart from the point light source 14, even if quantum dots and quantum rods are used, durability does not deteriorate.
  • the light emitted from the point light source 14 can be spread and guided in the in-plane direction by the action of the concave portion 30 that is a light incident portion.
  • the concave portion 30 is preferably a rotationally symmetric shape and particularly preferably a cylindrical shape from the viewpoint of enhancing the in-plane uniformity of light.
  • the incident surface 31 which is a side wall surface of the recessed part 30 is a cylindrical surface.
  • the incident surface 31 only needs to have a substantially vertical angle with the exit surface 20b, and specifically, it may be in a range of 90 ⁇ 10 °. That is, in this specification, “vertical” is used as a concept including substantially vertical of ⁇ 10 °. From the viewpoint of increasing the efficiency with which light from the point light source 14 enters the light guide 20, the angle formed by the incident surface 31 and the exit surface 20b is preferably in the range of 90 ⁇ 5 °.
  • a part 101 of the light beam emitted from the point light source 14 and impinging on the incident surface 31 of the light incident portion 30 is indicated by an arrow.
  • the light beam 101 enters the light guide 20 from the incident surface 31.
  • the light beam 101 is refracted at the interface between the air and the incident surface 31, and the angle ⁇ formed by the light beam 101 incident on the light guide 20 and the normal line of the incident surface 31 is totally reflected. Smaller than the corner. ⁇ ⁇ 45 degrees.
  • the light beam 101 reaches the emission surface 20 b of the light guide 20.
  • the light beam 101 reaches the one surface 20a facing the emission surface 20b of the light guide 20, but is totally reflected also on this one surface 20a by the same consideration as described above.
  • the light beam 101 guides the inside of the light guide 20 while repeating total reflection on the exit surface 20b and the one surface 20a until it hits the light extraction mechanism 40.
  • a part 102 of the light beam emitted from the point light source 14 and hitting the reflecting surface 33 a provided on the bottom surface 32 of the concave portion in the light incident portion 30 is indicated by an arrow.
  • the light beam 102 is reflected by the reflecting surface 33 a and returned again into the recess 30, and a part of the light beam 102 enters the incident surface 31. Thereafter, the light beam 102 enters the light guide 20 from the vertical surface of the light incident portion 30, and thereafter guides the light in the same manner as described above.
  • the incident surface 31 of the recess 30 Since the incident surface 31 of the recess 30 is perpendicular to the exit surface 20b, the amount of light that is directly emitted from the exit surface 20b out of the light incident from the entrance surface 31 is determined by the incident surface 31 relative to the exit surface 20b. In comparison with the case where the light is not vertical, more light can be guided in the in-plane direction among the light introduced into the light guide 20.
  • the reflection surface 33a provided inside the recess 30 not only suppresses the emission of high-intensity light directly above the point light source 14, but also reflects the light to be a vertical surface. By making it enter from the surface 31, it contributes to raising the utilization efficiency of light and improving the brightness
  • the reflective layer 33 constituting the reflective surface 33a can be formed of, for example, a metal thin film.
  • a metal thin film For example, silver or the like can be used for the metal thin film.
  • a transparent film a well-known organic substance and an inorganic substance can be used, for example, a silicone resin, a silicon oxide, etc. can be used. Further, by appropriately adjusting the refractive index and the film thickness of the transparent coating, the reflectance of the reflecting surface can be further increased, and the wavelength dependency of the reflectance can be controlled.
  • the reflective layer 33 may be a dielectric multilayer film.
  • the dielectric multilayer film preferably includes at least a Bragg reflective layer.
  • the Bragg reflection layer is a layer having a refractive index modulation in the thickness direction of the layer. In the Bragg reflection layer, when light having a component orthogonal to the refractive index modulation is incident, transmitted light and reflected light are generated at each refractive index interface, and they interfere with each other. Part is reflected.
  • the Bragg reflection layer has a periodic multilayer structure, and the reflectance can be controlled by increasing or decreasing the number of layers.
  • the selective reflection in the Bragg reflection layer can select the reflection wavelength by controlling the thickness of each layer in the multilayer structure.
  • the Bragg reflection layer for example, it can be produced by alternately laminating dozens of silicon oxide and niobium pentoxide thin films. Moreover, it can produce also by carrying out multilayer lamination of the polymer film. As a commercial product, a multilayer reflective film “ESR” manufactured by 3M, etc. can be used.
  • the reflectance by the reflective layer 33 is preferably 90% or more, and more preferably 95% or more.
  • the transmittance of the reflective layer 33 is preferably 10% or less, more preferably 5% or less, and most preferably 1% or less.
  • a light absorption layer may be provided on the exit surface side of the reflective layer 33. In this case, light that is not reflected by the reflection layer 33 and transmitted is absorbed by the light absorption layer, and light leakage directly above the point light source 14 can be suppressed to suppress luminance unevenness.
  • the light guide 20 has a light extraction mechanism 40 for extracting light from the inside of the light guide to the outside.
  • the light extraction mechanism 40 is a structure for emitting light from the inside of the light guide with uniform luminance.
  • the light extraction mechanism 40 can be formed, for example, by attaching a minute depression or protrusion to the one surface 20a or the emission surface 20b of the light guide 20.
  • the light extraction mechanism 40 may be a light scattering structure provided on the one surface 20a or the emission surface 20b.
  • the light scattering structure can be produced, for example, by arranging light scattering particles on the surface or providing a fine uneven structure on the surface.
  • the light extraction mechanism 40 breaks the total reflection condition of the light when light guided by repeating total reflection in the light guide 20 is incident on the light extraction mechanism 40, and the light is emitted from the light guide 20. Any structure that emits light may be used.
  • the light extraction mechanism 40 is configured by a concave portion that is finer than the concave portion 30 that constitutes the light incident portion provided on the one surface 20 a of the light guide 20.
  • FIG. 6 shows a light beam 104 that enters from the recess 30, guides the inside of the light guide 20, and then exits from the light extraction mechanism 40.
  • the path of the light beam 104 is bent due to refraction, reflection, scattering, or the like in the light extraction mechanism 40. As a result, at least a part of the light beam 104 can no longer be guided and is emitted to the outside of the light guide 20.
  • the light extraction mechanism 40 may extract light from the inside of the light guide 20 toward the one surface 20a. However, in this case, most of the extracted light is reflected by the reflecting plate 12, enters the light guide 20 again, and finally exits from the exit surface 20 b of the light guide 20.
  • the light extraction mechanism 40 may be randomly arranged in the surface 20a or the emission surface 20b of the light guide 20, or may be periodically arranged, and has a distributed structure in the surface. May be arranged. Moreover, you may be provided in both the one surface 20a and the output surface 20b.
  • the light extraction mechanism 40 includes a large number of light extraction mechanisms 40 so that the luminance of the extracted light is uniform. As an example, as shown in the upper diagram of FIG. 3, the light extraction mechanism 40 is arranged such that the density is lower as it is closer to the light incident part 30, and the density is higher as the distance from the light incident part 30 increases. As a result, the luminance of the light from the point light source 14 is made uniform and emitted for each fixed region centered on each point light source 14.
  • the structure prevents the light guide 20 from adhering to an adjacent member such as the reflector 12 or the diffusion sheet. It can also serve as.
  • the shape of the concave portion or the convex portion is not particularly limited, and is a quadrangular pyramid shape, a hemispherical shape, a conical shape, a polygonal pyramid shape, or a truncated cone shape. It may be a polygonal frustum shape.
  • the size of the concave portion or the convex portion is flat so that the shape of the light extraction mechanism 40 is not visually recognized when the planar lighting device is turned on. It is preferably smaller than the point light source 14 in view. Specifically, it is preferably a size that does not protrude from a circle having a diameter of 1 ⁇ m to 200 ⁇ m.
  • the light extraction mechanism 40 can be manufactured by imprinting using a mold, injection molding, or the like. Moreover, it can also produce by forming a recessed part in the surface of the light guide 20 by mechanical cutting or laser processing. Furthermore, it can also be produced by printing white ink or the like on the surface of the light guide 20.
  • FIG. 7 is a schematic cross-sectional view of the backlight unit 3 including the light guide 21 according to the design change example.
  • elements that are the same as those of the backlight unit 2 are denoted by the same reference numerals.
  • the concave portion 30 of the light guide 21 shown in FIG. 7 has a convex shape on the incident surface side as the bottom surface 32 approaches the central portion, and a reflective layer 33 is formed on the convex surface.
  • a part 103 of the light beam emitted from the point light source 14 and impinging on the reflection surface 33 a is reflected by the reflection surface 33 a and its path is greatly bent in the in-plane direction of the light guide 20. Therefore, the rate at which the light beam 103 reflected by the reflecting surface 33a is incident on the incident surface 31 of the light incident portion 30 can be increased, and the rate at which the light is guided in the in-plane direction can be increased.
  • FIG. 9 shows a schematic configuration of the liquid crystal display device 301 of the first embodiment.
  • silver was deposited in a thickness of 85 nm on the surface provided with the protective film, and a 250 ⁇ m thick silicon oxide film was deposited thereon.
  • the protective film was peeled off, silver and silicon oxide hardly adhered to the side wall surface 31 of the recess, and most adhered to the bottom surface 32 of the recess 30.
  • a reflective layer 33 is formed by the silver film and the silicon oxide film, and this reflective layer 33 constitutes a reflective surface.
  • the side wall surface 31 of the recess 30 is an incident surface on which light is incident.
  • a light extraction mechanism 40 having a conical depression shape with a bottom diameter of 100 ⁇ m and a depth of 150 ⁇ m was formed around the recess 30 formed in the acrylic plate using a CO 2 laser processing machine.
  • the light extraction mechanism 40 has a low density at a position close to the concave portion 30 that is a light incident portion, and is about 2000 per region centered on one light incident portion so that the density increases as the distance from the light incident portion increases.
  • a phosphor layer 60 including quantum dots was laminated on the reflective layer 33 of each recess 30.
  • the phosphor layer 60 was laminated as follows.
  • quantum dots quantum dots “INP530” and “INP650” manufactured by NN-Labs Co., Ltd. were used.
  • quantum dots are each dispersed in an acrylate “A-NOD-N” manufactured by Shin-Nakamura Chemical Co., Ltd. at a ratio of 10% by weight. Further, a photopolymerization initiator Irgacure 290 manufactured by BASF is added to 1% by weight. Mixed in proportion. This mixture was filled so as to occupy about 1 ⁇ 2 of the volume of the recess 30, and cured by UV (Ultra Violet) light having a wavelength of 365 nm. Thereby, the phosphor layer 60 was formed.
  • the light guide 201 was produced as described above.
  • planar illumination device 221 The light guide 201 is overlaid on the light source unit 11 so that each concave portion 30 covers the point light source 14, and the prism sheet taken out from the tablet terminal iPad (registered trademark) manufactured by Apple on the light emission surface side of the light guide 201 and the diffusion Sheets were stacked to produce the planar lighting device 221 of this example.
  • the liquid crystal display device 301 of Example 1 shown in FIG. 9 was produced by replacing the backlight of the tablet terminal iPad (registered trademark) with the planar illumination device 221 of this example.
  • Example 2 In the light guide 201 of Example 1, silver was changed to aluminum in the material of the reflective layer 33 provided on the bottom surface 32 of the recess 30. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 302 of Example 2.
  • FIG. 1 In the light guide 201 of Example 1, silver was changed to aluminum in the material of the reflective layer 33 provided on the bottom surface 32 of the recess 30. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 302 of Example 2.
  • Example 3 In the light guide 201 of Example 1, the reflective layer 33 provided on the bottom surface 32 of the recess 30 was changed to a dielectric multilayer film.
  • the dielectric multilayer film was formed by alternately stacking 13 layers of silicon oxide films having a thickness of 40 ⁇ m and niobium pentoxide films having a thickness of 100 ⁇ m. Each layer was formed by sputtering. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 303 of Example 3.
  • FIG. 9 shows a schematic configuration of the liquid crystal display device 304 of the fourth embodiment.
  • the concave portion 30 was formed by a CO 2 laser instead of mechanical cutting. Under the present circumstances, it formed so that the bottom face 32 of the recessed part 30 might form a convex shape to one surface side as it approaches the center part of a reflective surface. The peak of the convex shape was a distance of about 100 ⁇ m from the deepest position of the concave portion 30.
  • the bottom surface 32 of the recess 30 is constituted by a conical surface of a cone having a height of 100 ⁇ m.
  • a planar illumination device 224 was produced in the same manner as in Example 1 except that the light guide 204 was used, and a liquid crystal display device 304 of Example 4 shown in FIG. 10 was produced.
  • Example 5 In the light guide 201 of Example 1, the concave portion 30 was formed by a CO2 laser instead of mechanical cutting. At this time, the recess 30 was formed to have a quadrangular prism shape. The bottom surface of the recess was a substantially horizontal plane with respect to the incident surface of the acrylic plate. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 305 of Example 5.
  • FIG. 5 In the light guide 201 of Example 1, the concave portion 30 was formed by a CO2 laser instead of mechanical cutting. At this time, the recess 30 was formed to have a quadrangular prism shape. The bottom surface of the recess was a substantially horizontal plane with respect to the incident surface of the acrylic plate. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 305 of Example 5. FIG.
  • FIG. 10 shows a schematic configuration of the liquid crystal display device 312 of Comparative Example 2.
  • a concave portion 30 having a diameter of 1000 ⁇ m and a depth of 450 ⁇ m was formed on one surface of an acrylic plate having a thickness of 500 ⁇ m (“Clarex” manufactured by Nitto Resin Co., Ltd.). At this time, a total of 100 recesses 30 were provided at positions corresponding to the positions of the point light sources 15 of the light source unit 11.
  • the recessed part 30 was cylindrical, the side wall surface 31 of the recessed part 30 was perpendicular
  • a PET protective film having a hole with a diameter of 1200 ⁇ m at a position corresponding to the concave portion 30 was bonded to the exit surface, that is, the surface not drilled, which is the other surface of the acrylic plate.
  • Silver was vapor-deposited with a thickness of 85 nm on the surface provided with the protective film, and a silicon oxide film with a thickness of 250 ⁇ m was vapor-deposited thereon.
  • the protective film was peeled off to produce a light guide body 212 in which a reflective layer 33 made of a silver film and a silicon oxide film was formed at a position corresponding to the concave portion 30 on the emission surface side.
  • a liquid crystal display device 312 of Comparative Example 2 shown in FIG. 10 was produced using a planar illumination device 232 produced in the same manner as in Example 1 except that the light guide 212 was used.
  • FIG. 11 shows a schematic configuration of the liquid crystal display device 313 of Comparative Example 3.
  • the light guide 213 of the present embodiment is the same as the light guide 201 of the first embodiment except that the angle formed by the side wall surface 31 of the recess 30 with the exit surface is 60 degrees and the recess 30 has a truncated cone shape. This was produced in the same manner as in Example 1.
  • a planar illumination device 233 was produced in the same manner as in Example 1 except that the light guide 213 was used, and a liquid crystal display device 313 of Comparative Example 3 shown in FIG. 11 was produced.
  • FIG. 12 shows a schematic configuration of a liquid crystal display device 314 of Comparative Example 4.
  • the light guide 214 the light guide 201 of Example 1 that does not include the phosphor layer 60 was used.
  • the light guide body 214 was stacked on the light source unit 11 so that the respective concave portions covered the light emitting diodes, and a quantum dot sheet “QDEF” manufactured by 3M Company was stacked as the phosphor sheet 215 on the emission surface side of the light guide body 214.
  • a prism sheet and a diffusion sheet taken out from the tablet terminal iPad (registered trademark) manufactured by Apple were laminated on the phosphor sheet 215 to produce a planar illumination device 234.
  • planar lighting devices of Examples 1 to 5 and Comparative Examples 1 to 3 were all thin backlight units having an overall thickness in the range of 1 mm to 2 mm.
  • planar lighting device of Example 1 used silver as the material of the reflective layer, a higher average luminance was obtained compared to the planar lighting device of Example 2 using aluminum.
  • the concave portion was formed in a quadrangular prism shape, the light guide of incident light was not isotropic in the surface, and a region with high luminance and a region with low luminance were partially observed. .
  • planar illumination device of Comparative Example 1 does not use the light guide of the present disclosure, the luminance is not uniformed, and strong light leakage is seen directly above the point light source.
  • the reflective layer is not provided on the upper surface of the concave portion of the light incident portion, and the reflective layer is provided on the exit surface of the light guide. For this reason, light leaked from between the upper surface of the concave portion of the light incident portion and the reflective layer, and a relatively strong light leak was seen directly above the point light source. For this reason, the luminance uniformity was low.
  • the wall surface of the concave portion of the light incident portion is not perpendicular to the incident surface, and therefore, a part of the light hitting the wall surface of the concave portion is not guided after being incident on the light guide. Was leaking light. For this reason, the luminance uniformity was low.
  • the surface illumination device of Comparative Example 4 had luminance uniformity equivalent to that of Examples 1-5. On the other hand, the thickness of the phosphor sheet was larger than that of Examples 1 to 5.
  • planar illumination device and the liquid crystal display device of the present disclosure are thin, can obtain uniform illumination light and image display with little luminance unevenness, and can also perform local dimming.
  • planar illumination device of the present disclosure can be used not only as a backlight unit in the above-described liquid crystal display device but also as a backlight of a signboard, a sign, etc., a room light, and the like.

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Abstract

A planar illumination device comprising: a plate-shaped light guide comprising one surface comprising a plurality of recessed sections and an emission surface that emits light, said light guide having therein a light extracting mechanism that reflects, refracts, or scatters light that has been guided thereto; and a light source having a plurality of point light sources each having at least part thereof housed in the plurality of recessed sections. Each of the plurality of recessed sections has an incidence surface that is vertical relative to the emission surface and causes light from the point light source to be incident inside the light guide and a reflective surface that faces the point light source and reflects light from the point light source. Each of the plurality of recessed sections comprises a phosphor arranged between the reflective surface and the point light source, spaced apart from the point light source. The liquid crystal display device comprises the planar illumination device.

Description

面状照明装置および液晶表示装置Surface illumination device and liquid crystal display device
　本開示は、面状照明装置および面状照明装置を備えた液晶表示装置に関する。 The present disclosure relates to a planar illumination device and a liquid crystal display device including the planar illumination device.
　液晶表示装置（ＬＣＤ：Ｌｉｑｕｉｄ　Ｃｒｙｓｔａｌ　Ｄｉｓｐｌａｙ）は、消費電力が小さく、省スペースの画像表示装置として年々その用途が広がっている。液晶表示装置は、一例として、バックライトユニット、バックライト側偏光板、液晶パネルおよび視認側偏光板などが、この順で設けられた構成となっている。 Liquid crystal display devices (LCD: Liquid Crystal Display) have low power consumption and are increasingly used year by year as space-saving image display devices. As an example, the liquid crystal display device has a configuration in which a backlight unit, a backlight side polarizing plate, a liquid crystal panel, a viewing side polarizing plate, and the like are provided in this order.
　バックライトユニットとしては、例えば、導光板と、その端面に配置した光源とを備え、光源から端面に入射された光を導光して主面全体から液晶パネルに向け照射するエッジライト型（サイドライト型と称する場合もある）、および導光板を用いず、液晶パネルの直下に光源を配置して、光源上に備えられた光拡散板の主面全体から液晶パネルに向け照射する直下型が知られている。 The backlight unit includes, for example, an edge light type (side) that includes a light guide plate and a light source disposed on an end surface thereof, guides light incident on the end surface from the light source, and irradiates the liquid crystal panel from the entire main surface. There is also a direct type that irradiates the liquid crystal panel from the entire main surface of the light diffusing plate provided on the light source without using the light guide plate and arranging the light source directly under the liquid crystal panel. Are known.
　近年、映像表示の高画質化技術として、ＨＤＲ（Ｈｉｇｈ　Ｄｙｎａｍｉｃ　Ｒａｎｇｅ）が注目されている。ＨＤＲは映像の明部と暗部のコントラスト（明暗比）を向上させる表示技術であり、ＬＣＤにおけるＨＤＲは、通常、複数の点光源を面内に配置した直下型バックライトユニットを用いて、点光源を部分的に点灯・消灯させるローカルディミングを行って実現される。 In recent years, HDR (High Dynamic Range) has attracted attention as a technology for improving the image quality of video display. HDR is a display technology that improves the contrast (brightness / darkness ratio) between the bright and dark parts of an image, and HDR in an LCD usually uses a direct-type backlight unit in which a plurality of point light sources are arranged in a plane. This is realized by performing local dimming that partially turns on / off.
　しかしながら、直下型バックライトユニットは薄型化が困難であり、既存のものでは１５ｍｍ以上の厚みがある。
　直下型バックライトユニットにおいては、点光源からの光を拡散させ、出射光の面内における輝度ムラ（面内輝度の不均一性）を低減する目的で、通常、光拡散板が用いられる。また、光出射面全体で輝度ムラの少ない照射光を得るためには、光拡散板と点光源の間は十分な距離をとる必要がある。特に近年は、省電力化および小型化の要請によりＬＥＤ（Ｌｉｇｈｔ　ｅｍｉｔｔｉｎｇ　ｄｉｏｄｅ）光源が主流である。ＬＥＤ光源は指向性が強いため、光拡散板とＬＥＤ光源との間の距離を十分にとらなければ、ＬＥＤ直上が非常に明るくなり、著しい輝度ムラが生じてしまう。このような理由から、直下型バックライトユニットは薄型化が難しい。 However, it is difficult to reduce the thickness of the direct type backlight unit, and the existing type has a thickness of 15 mm or more.
In the direct type backlight unit, a light diffusing plate is usually used for the purpose of diffusing light from a point light source and reducing unevenness of brightness (unevenness of in-plane brightness) in the plane of outgoing light. Further, in order to obtain irradiation light with little luminance unevenness on the entire light emitting surface, it is necessary to provide a sufficient distance between the light diffusion plate and the point light source. Particularly in recent years, LED (Light Emitting Diode) light sources have become mainstream due to demands for power saving and miniaturization. Since the LED light source has strong directivity, unless a sufficient distance is provided between the light diffusing plate and the LED light source, the portion directly above the LED becomes very bright and significant luminance unevenness occurs. For this reason, it is difficult to reduce the thickness of the direct type backlight unit.
　特開２０１０－２７７０８６号公報（以下において、特許文献１という。）には、ＬＥＤ光源上に複数層の導光層を備え、導光層の界面に凹凸を設けることで、光源からの光線を凹凸で屈折、散乱あるいは反射させて導光層へ入射させ、導光層内において光を面内方向に拡げて導光させ、直下型バックライトでありながら薄型で輝度均一化を図った技術が開示されている。 Japanese Patent Application Laid-Open No. 2010-277086 (hereinafter referred to as Patent Document 1) includes a plurality of light guide layers on an LED light source, and by providing irregularities at the interface of the light guide layer, the light from the light source is emitted. A technology that refracts, scatters, or reflects by unevenness and enters the light guide layer, spreads light in the light guide layer in the in-plane direction, guides light, and achieves uniform brightness even though it is a direct type backlight. It is disclosed.
　特開２０１０－８０２８０号公報（以下において、特許文献２という。）には、一方の面が光の出射面とされ、出射面の反対側の面に複数の凹部が設けられた導光板と、凹部のそれぞれに格納され、導光板の延在する方向に光を出射し、光の出射方向が異なる向きに配置された少なくとも２つの発光素子（点光源）とを備えた面光源装置が提案されている。 Japanese Patent Laid-Open No. 2010-80280 (hereinafter referred to as Patent Document 2) discloses a light guide plate in which one surface is a light emission surface and a plurality of recesses are provided on the surface opposite to the emission surface. A surface light source device is proposed that includes at least two light emitting elements (point light sources) that are stored in each of the recesses, emit light in a direction in which the light guide plate extends, and are arranged in different directions. ing.
　しかしながら、本発明者らの検討によれば、特許文献１の技術では、光源から出射された光を各導光層へ充分に効率よく入射させることが困難であり、輝度ムラの抑制および光利用効率の向上を十分に実現することができない。 However, according to the study by the present inventors, it is difficult for the technique of Patent Document 1 to make the light emitted from the light source incident sufficiently efficiently on each light guide layer, thereby suppressing luminance unevenness and using light. Efficiency improvement cannot be realized sufficiently.
　一方、特許文献２のように、点光源からの光を凹部の面から導光板内に入射させる方法によれば、光源と導光板との距離を近接配置できるため、装置の薄型化が図れ、かつ均一な発光を行うことが可能となる。 On the other hand, according to the method of causing light from a point light source to enter the light guide plate from the surface of the recess as in Patent Document 2, the distance between the light source and the light guide plate can be arranged close to each other. In addition, uniform light emission can be performed.
　面状照明装置に備えられる点光源としては、一般的には白色ＬＥＤが用いられている。
白色ＬＥＤとしては、青色の単色光源に蛍光体層を積層したものが用いられる。しかし、このような白色ＬＥＤは蛍光体層が付与されているために、１ｍｍ程度の大きさを有している。従って、白色ＬＥＤを用いると薄型化が十分に図れない。 Generally, a white LED is used as a point light source provided in the planar illumination device.
As white LED, what laminated | stacked the fluorescent substance layer on the blue monochromatic light source is used. However, since such a white LED is provided with a phosphor layer, it has a size of about 1 mm. Therefore, if a white LED is used, the thickness cannot be sufficiently reduced.
　本開示は、上記事情に鑑み、薄型であり、かつ均一で輝度ムラが少ない照明光を出射することができる面状照明装置および面状照明装置を備えた液晶表示装置を提供することを目的とする。 In view of the above circumstances, an object of the present disclosure is to provide a planar illumination device capable of emitting illumination light that is thin, uniform, and has less luminance unevenness, and a liquid crystal display device including the planar illumination device. To do.
　本開示の技術には、以下の態様が含まれる。
＜１＞
　複数の凹部を備えた一面、および光を出射する出射面を備えた板状の導光体であって、内部で導光される光を反射、屈折あるいは散乱させる光取出し機構を有する導光体と、各々の少なくとも一部が複数の凹部の各々に収容される複数の点光源を有する光源部とを備え、複数の凹部の各々は、出射面に対して垂直であり、かつ、点光源からの光を導光体内に入射させる入射面と、点光源に対向し、かつ、点光源からの光を反射する反射面とを有し、複数の凹部の各々が、反射面と点光源との間に、点光源と離隔して配置された蛍光体を備えた面状照明装置。
＜２＞
　蛍光体が、少なくとも緑色を発光する蛍光体と赤色を発光する蛍光体とを含む＜１＞に記載の面状照明装置。
＜３＞
　蛍光体が、量子ドットを含む、＜１＞または＜２＞に記載の面状照明装置。
＜４＞
　点光源が近紫外発光ダイオード、または青色発光ダイオードである、＜１＞から＜３＞のいずれかに記載の面状照明装置。
＜５＞
　複数の点光源の各々が、各々の凹部の反射面に向けて光を出射する＜１＞から＜４＞のいずれか１項に記載の面状照明装置。
＜６＞
　入射面が、円筒面である＜１＞から＜５＞のいずれかに記載の面状照明装置。
＜７＞
　反射面が金属薄膜からなる、＜１＞から＜６＞のいずれかに記載の面状照明装置。
＜８＞
　金属薄膜が少なくとも銀を含んでなる、＜７＞に記載の面状照明装置。
＜９＞
　反射面が誘電体多層膜からなる、＜１＞から＜６＞のいずれかに記載の面状照明装置。
＜１０＞
　反射面が、その反射面の中央部に近付くにつれて一面側に凸形状をなす、＜１＞から＜９＞のいずれかに記載の面状照明装置。
＜１１＞
　液晶表示素子と、＜１＞から＜１＞のいずれかに記載の面状照明装置とを備えた液晶表示装置。 The technology of the present disclosure includes the following aspects.
<1>
A light guide having a light extraction mechanism that reflects, refracts, or scatters light guided inside, one plate having a plurality of recesses and an emission surface that emits light. And a light source unit having a plurality of point light sources each of which is accommodated in each of the plurality of recesses, each of the plurality of recesses being perpendicular to the exit surface and from the point light source And a reflecting surface that faces the point light source and reflects the light from the point light source, and each of the plurality of recesses is formed between the reflecting surface and the point light source. A planar illuminating device including a phosphor disposed between and a point light source.
<2>
The planar illumination device according to <1>, wherein the phosphor includes at least a phosphor that emits green light and a phosphor that emits red light.
<3>
The planar illumination device according to <1> or <2>, wherein the phosphor includes quantum dots.
<4>
The planar illumination device according to any one of <1> to <3>, wherein the point light source is a near ultraviolet light emitting diode or a blue light emitting diode.
<5>
The planar illumination device according to any one of <1> to <4>, wherein each of the plurality of point light sources emits light toward the reflection surface of each recess.
<6>
The planar illumination device according to any one of <1> to <5>, wherein the incident surface is a cylindrical surface.
<7>
The planar illumination device according to any one of <1> to <6>, wherein the reflection surface is made of a metal thin film.
<8>
The planar illumination device according to <7>, wherein the metal thin film contains at least silver.
<9>
The planar illumination device according to any one of <1> to <6>, wherein the reflection surface is made of a dielectric multilayer film.
<10>
The planar illumination device according to any one of <1> to <9>, wherein the reflective surface has a convex shape toward one surface as it approaches the center of the reflective surface.
<11>
A liquid crystal display device comprising a liquid crystal display element and the planar illumination device according to any one of <1> to <1>.
　本開示によれば、薄型な形状で、均一で輝度ムラが少ない照明光を出射する面状照明装置、および面状照明装置を備えた液晶表示装置を提供することができる。 According to the present disclosure, it is possible to provide a planar illumination device that emits illumination light that has a thin shape, is uniform, and has less luminance unevenness, and a liquid crystal display device that includes the planar illumination device.
本発明の一実施形態の液晶表示装置の概略構成を示す断面模式図である。It is a cross-sectional schematic diagram which shows schematic structure of the liquid crystal display device of one Embodiment of this invention. バックライトユニットの光源部の平面模式図である。It is a plane schematic diagram of the light source part of a backlight unit. バックライトユニットの導光体の一部の平面模式図および断面模式図である。It is the one part plane schematic diagram and cross-sectional schematic diagram of the light guide of a backlight unit. 導光体の内部を導光する光線の一部を示す、導光体の断面模式図である。It is a cross-sectional schematic diagram of a light guide which shows a part of light beam which guides the inside of a light guide. 導光体の内部を導光する光線の一部を示す、導光体の断面模式図である。It is a cross-sectional schematic diagram of a light guide which shows a part of light beam which guides the inside of a light guide. 導光体の内部を導光し、導光体の外部へ出射する光線の一部を示す、導光体の断面模式図である。It is a cross-sectional schematic diagram of a light guide which shows a part of light ray which guides the inside of a light guide and is radiate | emitted outside the light guide. 設計変更例の導光体の断面模式図である。It is a cross-sectional schematic diagram of the light guide of the example of a design change. 実施例１の液晶表示装置の一部を示す断面模式図である。3 is a schematic cross-sectional view showing a part of the liquid crystal display device of Example 1. FIG. 実施例４の液晶表示装置の一部を示す断面模式図である。6 is a schematic cross-sectional view showing a part of the liquid crystal display device of Example 4. FIG. 比較例２の液晶表示装置の一部を示す断面模式図である。10 is a schematic cross-sectional view showing a part of the liquid crystal display device of Comparative Example 2. FIG. 比較例３の液晶表示装置の一部を示す断面模式図である。10 is a schematic cross-sectional view showing a part of the liquid crystal display device of Comparative Example 3. FIG. 比較例４の液晶表示装置の一部を示す断面模式図である。10 is a schematic cross-sectional view showing a part of a liquid crystal display device of Comparative Example 4. FIG.
　以下、本開示の実施形態について図面を用いて説明するが、本開示はこれに限られるものではない。なお、視認しやすくするため、図面中の各構成要素の縮尺等は実際のものとは適宜変更している。また、本明細書において「～」を用いて表される数値範囲は、特に断りが無い限り「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。 Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited thereto. In addition, in order to make it easy to visually recognize, the scale of each component in the drawings is appropriately changed from the actual one. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit unless otherwise specified.
［液晶表示装置］
　図１は本開示の一実施形態の液晶表示装置１の概略構成を示す断面図である。
　液晶表示装置１は、画像表示面と反対側のバックライト入射面からバックライトが入射される液晶表示素子５０と、液晶表示素子５０のバックライト入射面側に配置されたバックライトユニット２とを備えている。液晶表示素子５０は、液晶パネル、その視認側に設けられた視認側偏光板およびバックライト側に設けられたバックライト側偏光板を含む。バックライトユニット２は、本開示の面状照明装置の一実施形態である。 [Liquid Crystal Display]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device 1 according to an embodiment of the present disclosure.
The liquid crystal display device 1 includes a liquid crystal display element 50 on which a backlight is incident from a backlight incident surface opposite to the image display surface, and a backlight unit 2 disposed on the backlight incident surface side of the liquid crystal display element 50. I have. The liquid crystal display element 50 includes a liquid crystal panel, a viewing side polarizing plate provided on the viewing side thereof, and a backlight side polarizing plate provided on the backlight side. The backlight unit 2 is an embodiment of the planar illumination device of the present disclosure.
［バックライトユニット］
　バックライトユニット２は、二次元配列された複数の点光源１４を備えた光源部１０と、複数の凹部３０を備えた一面２０ａ、および一面２０ａに対向する面であり、光を出射する出射面２０ｂを備えた導光体２０とを備えている。導光体２０は、内部で導光される光を反射、屈折あるいは散乱させる光取出し機構４０を有する板状の部材である。複数の凹部３０の各々は、出射面２０ｂに対して垂直であり、かつ、点光源１４からの光を導光体２０内に入射させる入射面３１と、点光源１４に対向し、かつ、点光源１４からの光を反射する反射面３３ａとを有する。また、複数の凹部３０の各々は、反射面３３ａと点光源１４との間に、点光源１４と離隔して配置された蛍光体を備えている。 [Backlight unit]
The backlight unit 2 is a light source unit 10 including a plurality of point light sources 14 arranged two-dimensionally, a surface 20a including a plurality of recesses 30, and a surface facing the surface 20a, and an emission surface that emits light. And a light guide 20 having 20b. The light guide 20 is a plate-like member having a light extraction mechanism 40 that reflects, refracts, or scatters light guided inside. Each of the plurality of recesses 30 is perpendicular to the exit surface 20b, faces the incident surface 31 through which light from the point light source 14 enters the light guide 20, the point light source 14, and a point. A reflecting surface 33a that reflects light from the light source 14; In addition, each of the plurality of recesses 30 includes a phosphor disposed separately from the point light source 14 between the reflecting surface 33 a and the point light source 14.
　上記導光体２０によれば、点光源１４からの光が凹部３０の入射面３１に直接、あるいは反射面３３ａで反射された後に、導光体２０内に入射される。導光体２０に入射された光の少なくとも一部は、導光体２０内で面内方向に拡がり光取出し機構４０の作用により出射面２０ｂから取出される。これによって、面内輝度が均一化された光が出射面２０ｂから出射される。 According to the light guide 20, the light from the point light source 14 enters the light guide 20 either directly on the incident surface 31 of the recess 30 or after being reflected by the reflecting surface 33 a. At least a part of the light incident on the light guide 20 spreads in the in-plane direction within the light guide 20 and is extracted from the emission surface 20 b by the action of the light extraction mechanism 40. As a result, light with uniform in-plane luminance is emitted from the emission surface 20b.
　本液晶表示装置１においては、上記導光体２０を備えたバックライトユニット２から出射された面内均一性の高いバックライトを、液晶表示素子５０に入射させることができる。 In the present liquid crystal display device 1, a backlight with high in-plane uniformity emitted from the backlight unit 2 including the light guide 20 can be incident on the liquid crystal display element 50.
　バックライトユニット２は、上記導光体２０を備えており、輝度が均一化された光を出射することができるため、光源部１０と導光体２０との間に厚い空間は不要である。したがって、直下型バックライトでありながら従来と比べて非常に薄くすることができる。
　また、バックライトユニット２は直下型であるため、備えられている点光源の数だけの多分割のローカルディミングが可能である。 Since the backlight unit 2 includes the light guide 20 and can emit light with uniform brightness, a thick space between the light source unit 10 and the light guide 20 is not necessary. Therefore, it can be made very thin as compared with the conventional case although it is a direct type backlight.
Further, since the backlight unit 2 is a direct type, multi-division local dimming as many as the number of point light sources provided is possible.
　また、バックライトユニット２の薄型化により、液晶表示装置１全体としての薄型化も実現できる。さらに、ローカルディミングが可能であるため、薄型でありながら、ＨＤＲ表示が可能な液晶表示装置を実現できる。 In addition, by reducing the thickness of the backlight unit 2, the overall thickness of the liquid crystal display device 1 can be reduced. Furthermore, since local dimming is possible, a thin liquid crystal display device capable of HDR display can be realized.
　なお、バックライトユニット２は、導光体２０と液晶表示素子５０との間に、図示しないプリズムシート、拡散シート、および輝度向上シートなどを含んでいてもよい。 The backlight unit 2 may include a prism sheet, a diffusion sheet, a brightness enhancement sheet, and the like (not shown) between the light guide 20 and the liquid crystal display element 50.
　以下、光源部１０および導光体２０、並びに導光体２０による光均一化の作用について詳細に説明する。 Hereinafter, the light source unit 10, the light guide 20, and the light uniforming action by the light guide 20 will be described in detail.
［光源部］
　光源部１０は、導光体２０の複数の凹部３０に対応して配置された複数の点光源１４と、複数の点光源１４が配置されている反射板１２とを含む。図２は、光源部１０の平面模式図である。図２に示すように、本実施形態において、点光源１４は、反射板１２上に縦横に所定の間隔で均等に配置されている。なお、本開示の面状照明装置においては、点光源の配置は縦横に所定の間隔で均等に配置されている場合に限定されるものではない。 [Light source]
The light source unit 10 includes a plurality of point light sources 14 arranged corresponding to the plurality of concave portions 30 of the light guide 20 and a reflector 12 on which the plurality of point light sources 14 are arranged. FIG. 2 is a schematic plan view of the light source unit 10. As shown in FIG. 2, in the present embodiment, the point light sources 14 are evenly arranged at predetermined intervals on the reflector 12 in the vertical and horizontal directions. In the planar illumination device of the present disclosure, the arrangement of the point light sources is not limited to the case where the arrangement of the point light sources is evenly arranged at predetermined intervals in the vertical and horizontal directions.
　点光源１４は、導光体２０の凹部３０に備えられている後述の蛍光体を励起可能な光源であり、例えば、近紫外または青色を発光する単色光源である。例えば、発光ダイオード、あるいはレーザーダイオードを用いることができる。色再現性の向上と、より効率良く光を面内方向に拡げることができる点で、レーザー光源が好ましい。中でも、光源部を薄型化する点で、垂直共振器型面発光レーザー（ＶＣＳＥＬ：Ｖｅｒｔｉｃａｌ　Ｃａｖｉｔｙ　Ｓｕｒｆａｃｅ　Ｅｍｉｔｔｉｎｇ　Ｌａｓｅｒ）が好ましい。点光源は、対向して配置される、凹部３０の反射面３３ａに向けて光を出射するように配置することが好ましい。 The point light source 14 is a light source capable of exciting a phosphor described later provided in the concave portion 30 of the light guide 20, and is, for example, a monochromatic light source that emits near ultraviolet or blue light. For example, a light emitting diode or a laser diode can be used. A laser light source is preferable in that the color reproducibility is improved and the light can be spread more efficiently in the in-plane direction. Among these, a vertical cavity surface emitting laser (VCSEL) is preferable from the viewpoint of reducing the thickness of the light source. The point light source is preferably arranged so as to emit light toward the reflecting surface 33a of the recess 30 which is arranged to face the point light source.
　点光源１４の数はローカルディミングのエリア分割数に直結する。エリア分割数を上げるためには、点光源の数を増加させる必要がある。より小さいサイズの点光源を用いることにより、配置する点光源の個数を増加させることができる。このような点光源１４としては、１辺が３００μｍ以下、好ましくは２００μｍ以下のＬＥＤが好適である。 The number of point light sources 14 is directly linked to the number of area divisions for local dimming. In order to increase the number of area divisions, it is necessary to increase the number of point light sources. By using a point light source having a smaller size, the number of point light sources to be arranged can be increased. As such a point light source 14, an LED having one side of 300 μm or less, preferably 200 μm or less is suitable.
　反射板１２は、特に制限なく、公知のものが各種利用可能である。光を効率的に用いるために、吸収が小さく反射率が高い反射面を有することが好ましい。例えば、白色ＰＥＴ（ｐｏｌｙｅｔｈｙｌｅｎｅ　ｔｅｒｅｐｈｔｈａｌａｔｅ）、あるいはポリエステル系樹脂を用いた多層膜フィルムが挙げられる。白色ＰＥＴとしては、例えば、古河電気工業株式会社製のＭＣＰＥＴ（登録商標）が挙げられる。また、ポリエステル系樹脂を用いた多層膜フィルムとしては、例えば、３Ｍ社製のＥＳＲ（商品名）が挙げられる。点光源１４が配置される基板は反射板に限らない。しかしながら、点光源１４から導光体２０に向けて出射された光のうち、導光体２０あるいは、プリズムシート等により反射された光をさらに反射させて光の利用効率を上げるために、点光源１４を反射板１２上に配置することが好ましい。 The reflection plate 12 is not particularly limited, and various known ones can be used. In order to use light efficiently, it is preferable to have a reflecting surface with low absorption and high reflectance. For example, a multilayer film using white PET (polyethylene terephthalate) or a polyester resin can be used. Examples of white PET include MCPET (registered trademark) manufactured by Furukawa Electric Co., Ltd. Moreover, as a multilayer film using a polyester-type resin, 3SR ESR (brand name) is mentioned, for example. The board | substrate with which the point light source 14 is arrange | positioned is not restricted to a reflecting plate. However, in order to further improve the light utilization efficiency by further reflecting the light reflected by the light guide 20 or the prism sheet among the light emitted from the point light source 14 toward the light guide 20, the point light source 14 is preferably disposed on the reflector 12.
　また、反射板１２は、光源部１０において点光源１４が配置される部分を除く基板の表面を覆っていてもよい。この場合、反射板１２の厚みは点光源の厚みよりも薄いことが好ましく、例えば、点光源１４を実装した基板の表面に、薄い塗膜として形成されてもよい。反射性の塗膜は、例えば、基板の表面に白色インキ等を塗布することによって得られる。 Further, the reflection plate 12 may cover the surface of the substrate excluding a portion where the point light source 14 is disposed in the light source unit 10. In this case, the thickness of the reflecting plate 12 is preferably thinner than that of the point light source, and may be formed as a thin coating film on the surface of the substrate on which the point light source 14 is mounted, for example. The reflective coating film is obtained, for example, by applying white ink or the like to the surface of the substrate.
［導光体］
　導光体２０は、一面２０ａに入射された光源部１０からの光の輝度を均一化して出射面２０ｂから出射する面状の部材である。 [Light guide]
The light guide 20 is a planar member that equalizes the luminance of the light from the light source unit 10 incident on the one surface 20a and emits the light from the light emitting surface 20b.
　図３は、図１に示すバックライトユニット２の一部の平面模式図（上図）およびＩＩＩ－ＩＩＩ線断面模式図（下図）である。なお、図３において、下図における光取出し機構４０の配置および大きさは上図と一致していない。 FIG. 3 is a schematic plan view (upper view) and a schematic cross-sectional view taken along line III-III (lower view) of a part of the backlight unit 2 shown in FIG. In FIG. 3, the arrangement and size of the light extraction mechanism 40 in the lower diagram do not match those in the upper diagram.
　導光体２０の構成材料は特に限定されず、公知の板状物（シート状物）が、各種、利用可能である。一例として、ポリエチレンテレフタレート、ポリプロピレン、ポリカーボネート、ポリメチルメタクリレート等のアクリル樹脂、ベンジルメタクリレート、ＭＳ樹脂（ポリメタクリルスチレン）、シクロオレフィンポリマ、シクロオレフィンコポリマ、セルロースジアセテートおよびセルローストリアセテートなどのセルロースアシレート等、公知のバックライト装置に用いられる導光板と同様の、透明性が高い樹脂で形成された導光シートが挙げられる。上記樹脂は熱可塑性樹脂に限らず、例えば、紫外線硬化性樹脂、電子線硬化性樹脂等の電離放射線硬化性樹脂あるいは熱硬化性樹脂であってもよい。
　また、導光体２０はガラスあるいは石英等の、透明な無機物から形成されていてもよい。ガラスは樹脂に比較して、熱、湿度、または力が加わることによる変形が小さいため、光入射部３０の位置が点光源１４の位置と対応するように、導光体２０を設置することが容易になる。 The constituent material of the light guide 20 is not particularly limited, and various known plate-like materials (sheet-like materials) can be used. As an example, acrylic resin such as polyethylene terephthalate, polypropylene, polycarbonate, polymethyl methacrylate, benzyl methacrylate, MS resin (polymethacryl styrene), cycloolefin polymer, cycloolefin copolymer, cellulose acylate such as cellulose diacetate and cellulose triacetate, etc. The light guide sheet formed with resin with high transparency similar to the light guide plate used for a well-known backlight apparatus is mentioned. The resin is not limited to a thermoplastic resin, and may be, for example, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin, or a thermosetting resin.
The light guide 20 may be formed of a transparent inorganic material such as glass or quartz. Since the glass is less deformed by applying heat, humidity, or force than the resin, the light guide 20 can be installed so that the position of the light incident portion 30 corresponds to the position of the point light source 14. It becomes easy.
　導光体２０の厚みは、１００μｍ～２０００μｍが好ましく、２００μｍ～１０００μｍがさらに好ましい。 The thickness of the light guide 20 is preferably 100 μm to 2000 μm, and more preferably 200 μm to 1000 μm.
　凹部３０は、点光源１４からの光を導光体２０内に入射させる入射部として機能する。凹部３０は一面２０ａに開口を有する凹部であり、既述の入射面３１として機能する側壁面（以下において、側壁面３１という場合もある。）と底面３２とから構成されている。導光体２０は、一面２０ａ側が光源部１０側であり、各凹部３０が各点光源１４を覆うように設置されており、各凹部３０の底面３２が点光源１４と対向する。これによって、光源部１０の複数の点光源１４は各々の少なくとも一部が複数の凹部３０の各々に収容されている。凹部３０の側壁面３１、すなわち、点光源１４から出射された光を導光体２０内に入射させる入射面３１は、出射面２０ｂに対して垂直な面である。そして、凹部３０の底面３２は反射層３３で覆われており、この反射層３３により、点光源１４から出射された光を反射する反射面３３ａが構成されている。すなわち、凹部３０は、出射面２０ａに対して垂直であり、かつ、点光源１４からの光を導光体２０内に入射させる入射面３１と、点光源１４に対向し、かつ、点光源１４からの光を反射する反射面３３ａとを有する。以下において凹部３０を入射部３０と称する場合がある。 The concave portion 30 functions as an incident portion for allowing the light from the point light source 14 to enter the light guide 20. The concave portion 30 is a concave portion having an opening on one surface 20a, and is composed of a side wall surface functioning as the above-described incident surface 31 (hereinafter also referred to as the side wall surface 31) and a bottom surface 32. The light guide 20 has the one surface 20 a side on the light source unit 10 side, and each recess 30 is installed so as to cover each point light source 14, and the bottom surface 32 of each recess 30 faces the point light source 14. Accordingly, at least a part of each of the plurality of point light sources 14 of the light source unit 10 is accommodated in each of the plurality of recesses 30. The side wall surface 31 of the recess 30, that is, the incident surface 31 for allowing the light emitted from the point light source 14 to enter the light guide 20 is a surface perpendicular to the emission surface 20 b. The bottom surface 32 of the recess 30 is covered with a reflection layer 33, and the reflection layer 33 constitutes a reflection surface 33 a that reflects light emitted from the point light source 14. That is, the concave portion 30 is perpendicular to the emission surface 20 a, faces the point light source 14 with the incident surface 31 through which light from the point light source 14 enters the light guide 20, and the point light source 14. And a reflection surface 33a for reflecting the light from the. Hereinafter, the concave portion 30 may be referred to as the incident portion 30.
　凹部３０は、開口の直径が点光源１４の大きさよりも大きく、点光源１４を覆うように設置される。平面視において、点光源１４を開口中に内包できる大きさである。好ましくは、２００μｍ～２０００μｍである。 The recess 30 is installed so that the diameter of the opening is larger than the size of the point light source 14 and covers the point light source 14. In a plan view, the point light source 14 is large enough to be included in the opening. Preferably, it is 200 μm to 2000 μm.
　凹部３０は、モールドを用いたインプリントや、射出成形等によって作製することができる。また、アクリル等の平板の表面を、機械切削やレーザー加工により貫通しないように穴あけすることによっても作製することができる。さらに、アクリル等の平板に機械切削あるいはレーザー加工により貫通穴をあけ、穴の一方の面に樹脂等を埋め込んだり、一方の面にアクリル等の薄いフィルムを貼合したりして、穴を塞ぐことによっても作製することができる。
　また、導光体２０の複数の凹部３０の各々は、その凹部３０の内側に、蛍光体を含む層６０を有している。凹部３０内において、蛍光体を含む層６０（以下において、蛍光体層６０という。）は、反射面３３ａと点光源１４との間に、点光源１４と離隔して配置されている。 The recess 30 can be produced by imprinting using a mold, injection molding, or the like. Alternatively, the surface of a flat plate made of acrylic or the like can be produced by drilling so as not to penetrate through mechanical cutting or laser processing. Furthermore, a through hole is made in a flat plate of acrylic or the like by machining or laser processing, and a resin or the like is embedded in one surface of the hole, or a thin film of acrylic or the like is bonded to one surface to close the hole. Can also be produced.
Each of the plurality of recesses 30 of the light guide 20 has a layer 60 containing a phosphor inside the recess 30. In the recess 30, a layer 60 containing phosphor (hereinafter referred to as “phosphor layer 60”) is disposed between the reflecting surface 33 a and the point light source 14 so as to be separated from the point light source 14.
　蛍光体としては、近紫外光あるいは青色光を青色光、緑色光、赤色光、または黄色光に変換する、任意の蛍光体を用いることができる。例えば、イットリウム・アルミニウム・ガーネット（ＹＡＧ）蛍光体、β―サイアロン蛍光体、ＣａＡｌＳｉＮ３：ＥＵ（ＣＡＳＮ）蛍光体、およびＫ２ＳｉＦ６：Ｍｎ４＋（ＫＳＦ）蛍光体等を好適に用いることができる。 As the phosphor, any phosphor that converts near ultraviolet light or blue light into blue light, green light, red light, or yellow light can be used. For example, an yttrium aluminum garnet (YAG) phosphor, a β-sialon phosphor, a CaAlSiN 3 : EU (CASN) phosphor, and a K 2 SiF 6 : Mn 4+ (KSF) phosphor can be suitably used. .
　また、蛍光体としては、量子ドット、または量子ロッドを用いることもできる。量子ドットまたは量子ロッドとしては、コアーシェル型の半導体ナノ粒子が、耐久性を向上する観点から好ましい。コアとしては、ＩＩ－ＶＩ族半導体ナノ粒子、ＩＩＩ－Ｖ族半導体ナノ粒子、及び多元系半導体ナノ粒子等を用いることができる。具体的には、ＣｄＳｅ、ＣｄＴｅ、ＣｄＳ、ＺｎＳ、ＺｎＳｅ、ＺｎＴｅ、ＩｎＰ、ＩｎＡｓ、ＩｎＧａＰ、およびＣｕＩｎＳ２等が挙げられるが、これらに限定されない。中でも、ＣｄＳｅ、ＣｄＴｅ、ＩｎＰ、ＩｎＧａＰ、およびＣｕＩｎＳ２が、高効率で可視光を発光する観点から、好ましい。シェルとしては、ＣｄＳ、ＺｎＳ、ＺｎＯ、ＧａＡｓ、およびこれらの複合体を用いることができるが、これらに限定されない。 Further, as the phosphor, quantum dots or quantum rods can be used. As a quantum dot or a quantum rod, a core-shell type semiconductor nanoparticle is preferable from a viewpoint of improving durability. As the core, II-VI semiconductor nanoparticles, III-V semiconductor nanoparticles, multi-component semiconductor nanoparticles, and the like can be used. Specifically, CdSe, CdTe, CdS, ZnS , ZnSe, ZnTe, InP, InAs, InGaP, and although CuInS 2, etc., without limitation. Among these, CdSe, CdTe, InP, InGaP, and CuInS 2 are preferable from the viewpoint of emitting visible light with high efficiency. As the shell, CdS, ZnS, ZnO, GaAs, and a composite thereof can be used, but the shell is not limited thereto.
　量子ドットまたは量子ロッドは、高い吸光度を有しているため、蛍光体層を薄くできる利点がある。また、量子ドットまたは量子ロッドは、組成および粒径の少なくとも一方を調整することによって、任意の発光波長を得ることができるため、点光源の発光波長と合わせて、高い輝度および、高い色再現性を得られるよう、調整することが容易である。 Quantum dots or quantum rods have an advantage that the phosphor layer can be made thin because they have high absorbance. In addition, since quantum dots or quantum rods can obtain an arbitrary emission wavelength by adjusting at least one of the composition and the particle size, high luminance and high color reproducibility are combined with the emission wavelength of a point light source. It is easy to adjust so that
　このように、導光体２０の光入射部となる凹部３０に蛍光体が備えられているので、点光源１４は単色光源とすることができる。導光体２０において、単色光源から出射した光を蛍光体で波長変換することによって、白色光、あるいはその他所望の発光色を得ることができる。 As described above, since the phosphor is provided in the concave portion 30 serving as the light incident portion of the light guide 20, the point light source 14 can be a monochromatic light source. In the light guide 20, white light or other desired emission color can be obtained by converting the wavelength of light emitted from the monochromatic light source with a phosphor.
　従来技術の項で説明した通り白色光源を構成するために一般的に使用される白色ＬＥＤは、青色の単色光源に蛍光体層を積層したものであり、１ｍｍ程度の大きさを有している。それに対し、単色発光ダイオード等の単色光源は、光源を数μｍ～数百μｍであるため、白色ＬＥＤを用いた面状照明装置と比較して、薄型化を図ることができる。
　白色光を得る方法としては、点光源として単色光源を用い、導光体２０の出射面側に蛍光体を含む蛍光体シートを配置し、近紫外光または青色光の一部を波長変換して、白色光を得ることも考えられる。しかしながら、単色光源を用いることで光源部を薄型化できても、蛍光体シートを用いることで、十分な薄型化は図れない。一方、上述の通り、導光体２０の凹部３０内に蛍光体層６０を備えることにより、単色光源を用いることができ、かつ蛍光体シートを備える必要がないため、面状照明装置の十分な薄型化が実現できる。また、蛍光体シートを用いる場合と比較して、蛍光体の使用量を削減することができる。 As described in the section of the prior art, a white LED generally used for constituting a white light source is obtained by laminating a phosphor layer on a blue monochromatic light source and has a size of about 1 mm. . On the other hand, since a monochromatic light source such as a monochromatic light emitting diode has a light source of several μm to several hundred μm, it can be made thinner than a planar illumination device using a white LED.
As a method for obtaining white light, a monochromatic light source is used as a point light source, a phosphor sheet containing a phosphor is disposed on the light exit surface side of the light guide 20, and a wavelength of a part of near ultraviolet light or blue light is wavelength-converted. It is also conceivable to obtain white light. However, even if the light source portion can be thinned by using a monochromatic light source, it cannot be sufficiently thinned by using a phosphor sheet. On the other hand, as described above, by providing the phosphor layer 60 in the concave portion 30 of the light guide 20, a monochromatic light source can be used and it is not necessary to provide a phosphor sheet. Thinning can be realized. Moreover, the usage-amount of fluorescent substance can be reduced compared with the case where a fluorescent substance sheet is used.
　なお、蛍光体としては、特に、量子ドットまたは量子ロッドを用いることが好ましい。量子ドットおよび量子ロッドは、ＹＡＧ蛍光体等を用いる場合と比較して、高い色再現性を得ることができる。一方で、量子ドットおよび量子ロッドは、耐熱性が低く、点光源と接触させて配置させた場合には、耐久性が低下する。しかし、本導光体２０においては、蛍光体層６０は点光源１４と離隔して配置されているため、量子ドットおよび量子ロッドを用いても、耐久性の低下を生じない。 In addition, it is particularly preferable to use quantum dots or quantum rods as the phosphor. Quantum dots and quantum rods can obtain high color reproducibility compared with the case of using a YAG phosphor or the like. On the other hand, quantum dots and quantum rods have low heat resistance, and durability is lowered when they are placed in contact with a point light source. However, in the present light guide 20, since the phosphor layer 60 is disposed apart from the point light source 14, even if quantum dots and quantum rods are used, durability does not deteriorate.
－光入射部－
　導光体２０においては、光入射部である凹部３０の作用により、点光源１４から出射された光を面内方向に拡げて導光させることができる。 -Light incident part-
In the light guide 20, the light emitted from the point light source 14 can be spread and guided in the in-plane direction by the action of the concave portion 30 that is a light incident portion.
　凹部３０は、光の面内均一性を高める観点では、回転対称の形状であることが好ましく、円柱状であることが特に好ましい。凹部３０が円柱状である場合、凹部３０の側壁面である入射面３１は円筒面である。ここで、入射面３１は、出射面２０ｂとのなす角がほぼ垂直であればよく、具体的には、９０±１０°の範囲であればよい。すなわち、本明細書において「垂直」とは、±１０°のほぼ垂直を含む概念として用いている。なお、点光源１４からの光が導光体２０に入射する効率を高める観点では、入射面３１と出射面２０ｂとのなす角が９０±５°の範囲であることが好ましい。 The concave portion 30 is preferably a rotationally symmetric shape and particularly preferably a cylindrical shape from the viewpoint of enhancing the in-plane uniformity of light. When the recessed part 30 is cylindrical, the incident surface 31 which is a side wall surface of the recessed part 30 is a cylindrical surface. Here, the incident surface 31 only needs to have a substantially vertical angle with the exit surface 20b, and specifically, it may be in a range of 90 ± 10 °. That is, in this specification, “vertical” is used as a concept including substantially vertical of ± 10 °. From the viewpoint of increasing the efficiency with which light from the point light source 14 enters the light guide 20, the angle formed by the incident surface 31 and the exit surface 20b is preferably in the range of 90 ± 5 °.
　図４～図６を参照して、導光体２０において光が面内方向に伝搬される原理を説明する。ここでは、凹部３０の入射面３１と導光体２０の出射面２０ｂとがちょうど９０度をなす場合について説明する。導光体内において、光を面内方向に導光させるためには、導光体２０内において、光を導光体２０と空気との界面で全反射させる必要がある。全反射角度は導光体２０の屈折率に依存するが、全反射角度は一般的に４５度未満である。例えば導光体の一般的な材料であるアクリルの屈折率は１．４９であるから、アクリルからなる導光体から空気（屈折率は１）に光が入る時の全反射角θ＝ａｒｃ・ｓｉｎ（１／１．４９）＝４２．２°である。 The principle that light is propagated in the in-plane direction in the light guide 20 will be described with reference to FIGS. Here, the case where the incident surface 31 of the recessed part 30 and the output surface 20b of the light guide 20 form exactly 90 degrees will be described. In order to guide light in the in-plane direction within the light guide, it is necessary to totally reflect the light at the interface between the light guide 20 and air in the light guide 20. Although the total reflection angle depends on the refractive index of the light guide 20, the total reflection angle is generally less than 45 degrees. For example, since the refractive index of acrylic, which is a general material of the light guide, is 1.49, the total reflection angle θ = arc · when light enters the air (refractive index is 1) from the light guide made of acrylic. sin (1 / 1.49) = 42.2 °.
　図４には、点光源１４から出射し、光入射部３０の入射面３１に当たる光線の一部１０１が、矢印で図示されている。光線１０１は、入射面３１から導光体２０の内部へと入射する。図４に示す例では、光線１０１は空気と入射面３１との界面において屈折し、導光体２０の内部に入射した光線１０１と、入射面３１の法線とのなす角αが、全反射角よりも小さい。
　α＜４５度
である。 In FIG. 4, a part 101 of the light beam emitted from the point light source 14 and impinging on the incident surface 31 of the light incident portion 30 is indicated by an arrow. The light beam 101 enters the light guide 20 from the incident surface 31. In the example shown in FIG. 4, the light beam 101 is refracted at the interface between the air and the incident surface 31, and the angle α formed by the light beam 101 incident on the light guide 20 and the normal line of the incident surface 31 is totally reflected. Smaller than the corner.
α <45 degrees.
　次に、光線１０１は、導光体２０の出射面２０ｂに到達する。入射面３１と出射面２０ｂがちょうど９０度をなす場合、光線１０１と出射面２０ｂの法線とのなす角βは、
　β＝９０度－α
であり、
　β＞　４５度
である。
　したがって、βは全反射角以上となり、光線１０１は出射面から出射することなく、全反射される。 Next, the light beam 101 reaches the emission surface 20 b of the light guide 20. When the incident surface 31 and the exit surface 20b are exactly 90 degrees, the angle β formed between the light beam 101 and the normal of the exit surface 20b is
β = 90 degrees -α
And
β> 45 degrees.
Therefore, β is equal to or greater than the total reflection angle, and the light beam 101 is totally reflected without being emitted from the emission surface.
　次に、光線１０１は、導光体２０の出射面２０ｂに対向する一面２０ａに到達するが、上記と同様の考察により、この一面２０ａにおいても全反射される。 Next, the light beam 101 reaches the one surface 20a facing the emission surface 20b of the light guide 20, but is totally reflected also on this one surface 20a by the same consideration as described above.
　このように、光線１０１は、光取り出し機構４０に当たるまで、出射面２０ｂと一面２０ａにおいて全反射を繰り返しながら、導光体２０の内部を導光していく。 Thus, the light beam 101 guides the inside of the light guide 20 while repeating total reflection on the exit surface 20b and the one surface 20a until it hits the light extraction mechanism 40.
　図５には、点光源１４から出射し、光入射部３０における凹部の底面３２に設けられている反射面３３ａに当たる光線の一部１０２が、矢印で図示されている。光線１０２は、反射面３３ａで反射されて再び凹部３０内へと戻され、その一部は入射面３１へと入射する。その後、光線１０２は光入射部３０の垂直面から導光体２０の内部へと入射し、以降は上述の場合と同様に導光する。 In FIG. 5, a part 102 of the light beam emitted from the point light source 14 and hitting the reflecting surface 33 a provided on the bottom surface 32 of the concave portion in the light incident portion 30 is indicated by an arrow. The light beam 102 is reflected by the reflecting surface 33 a and returned again into the recess 30, and a part of the light beam 102 enters the incident surface 31. Thereafter, the light beam 102 enters the light guide 20 from the vertical surface of the light incident portion 30, and thereafter guides the light in the same manner as described above.
　凹部３０の入射面３１が出射面２０ｂに対して垂直であることから、入射面３１から入射した光のうちそのまま出射面２０ｂから出射される光の量を、入射面３１が出射面２０ｂに対して垂直でない場合と比較して、抑制することができ、導光体２０に導入された光のうち、より多くの光を面内方向に導光させることができる。 Since the incident surface 31 of the recess 30 is perpendicular to the exit surface 20b, the amount of light that is directly emitted from the exit surface 20b out of the light incident from the entrance surface 31 is determined by the incident surface 31 relative to the exit surface 20b. In comparison with the case where the light is not vertical, more light can be guided in the in-plane direction among the light introduced into the light guide 20.
　このように、凹部３０の内部に設けられる反射面３３ａは、点光源１４の直上に高強度の光が出射されることを抑制するだけでなく、それらの光を反射して垂直面である入射面３１から入射させることにより、光の利用効率を高め、面状照明装置の輝度を向上させることに寄与する。 As described above, the reflection surface 33a provided inside the recess 30 not only suppresses the emission of high-intensity light directly above the point light source 14, but also reflects the light to be a vertical surface. By making it enter from the surface 31, it contributes to raising the utilization efficiency of light and improving the brightness | luminance of a planar illuminating device.
　反射面３３ａを構成する反射層３３は、例えば、金属薄膜により形成することができる。金属薄膜は、例えば銀などを用いることができる。また、金属薄膜の剥離や酸化を抑制する保護層として、金属薄膜にさらに透明被膜を積層してもよい。透明被膜としては、公知の有機物や無機物を用いることができ、例えば、シリコーン樹脂や酸化ケイ素等を用いることができる。また、透明被膜の屈折率と膜厚を適切に調整することにより、反射面の反射率をさらに高めたり、反射率の波長依存性を制御したりすることもできる。 The reflective layer 33 constituting the reflective surface 33a can be formed of, for example, a metal thin film. For example, silver or the like can be used for the metal thin film. Moreover, you may laminate | stack a transparent film further on a metal thin film as a protective layer which suppresses peeling and oxidation of a metal thin film. As a transparent film, a well-known organic substance and an inorganic substance can be used, for example, a silicone resin, a silicon oxide, etc. can be used. Further, by appropriately adjusting the refractive index and the film thickness of the transparent coating, the reflectance of the reflecting surface can be further increased, and the wavelength dependency of the reflectance can be controlled.
　また、反射層３３は、誘電体多層膜であってもよい。誘電体多層膜は、少なくともブラッグ反射層を含むことが好ましい。
　ブラッグ反射層は、層の厚さ方向に屈折率の変調を有する層である。ブラッグ反射層は、その屈折率変調に対して直交する成分を有する光が入射した際に、各屈折率界面において透過光および反射光が生じ、これらが互いに干渉し、その結果、入射光の一部が反射される。一般に、ブラッグ反射層は、周期的な多層構造を有し、層の数を増減することで反射率を制御することができる。また、ブラッグ反射層における選択反射は一般に、多層構造における個々の層の厚みを制御することで、反射波長を選択できる。
　ブラッグ反射層の一例としては、例えば、酸化ケイ素と五酸化ニオブの薄膜を交互に数十層、積層して作製することができる。また、高分子フィルムを多層積層することによっても作製することができる。市販品では、３Ｍ社製の多層反射フィルム「ＥＳＲ」等を用いることができる。 The reflective layer 33 may be a dielectric multilayer film. The dielectric multilayer film preferably includes at least a Bragg reflective layer.
The Bragg reflection layer is a layer having a refractive index modulation in the thickness direction of the layer. In the Bragg reflection layer, when light having a component orthogonal to the refractive index modulation is incident, transmitted light and reflected light are generated at each refractive index interface, and they interfere with each other. Part is reflected. In general, the Bragg reflection layer has a periodic multilayer structure, and the reflectance can be controlled by increasing or decreasing the number of layers. In general, the selective reflection in the Bragg reflection layer can select the reflection wavelength by controlling the thickness of each layer in the multilayer structure.
As an example of the Bragg reflection layer, for example, it can be produced by alternately laminating dozens of silicon oxide and niobium pentoxide thin films. Moreover, it can produce also by carrying out multilayer lamination of the polymer film. As a commercial product, a multilayer reflective film “ESR” manufactured by 3M, etc. can be used.
　反射層３３による反射率は、９０％以上であることが好ましく、９５％以上であることがさらに好ましい。 The reflectance by the reflective layer 33 is preferably 90% or more, and more preferably 95% or more.
　また、反射層３３の透過率は、１０％以下であることが好ましく、５％以下であることがさらに好ましく、１％以下であることが最も好ましい。反射層３３の透過率が大きいと、点光源１４の直上への光漏れが大きくなり、輝度ムラを生じてしまう。
　反射層３３の透過率を低減するため、反射層３３の出射面側に光吸収層を設けてもよい。この場合は、反射層３３で反射されず透過した光を光吸収層により吸収し、点光源１４の直上への光漏れを抑えて輝度ムラを抑制することができる。しかし、輝度を向上させる観点からは、透過率が１０％以下、かつ反射率が９０％以上である反射層３３を設け、光吸収層を設けないことが好ましい。 Further, the transmittance of the reflective layer 33 is preferably 10% or less, more preferably 5% or less, and most preferably 1% or less. When the transmittance of the reflective layer 33 is large, light leakage directly above the point light source 14 increases, resulting in uneven brightness.
In order to reduce the transmittance of the reflective layer 33, a light absorption layer may be provided on the exit surface side of the reflective layer 33. In this case, light that is not reflected by the reflection layer 33 and transmitted is absorbed by the light absorption layer, and light leakage directly above the point light source 14 can be suppressed to suppress luminance unevenness. However, from the viewpoint of improving luminance, it is preferable to provide the reflective layer 33 having a transmittance of 10% or less and a reflectance of 90% or more, and not to provide a light absorption layer.
［光取り出し機構］
　導光体２０は、導光体の内部から外部に光を取り出すための光取り出し機構４０を有する。光取り出し機構４０は、導光体の内部から光を均一な輝度で出射させるための構造である。 [Light extraction mechanism]
The light guide 20 has a light extraction mechanism 40 for extracting light from the inside of the light guide to the outside. The light extraction mechanism 40 is a structure for emitting light from the inside of the light guide with uniform luminance.
　光取り出し機構４０は、例えば、導光体２０の一面２０ａまたは出射面２０ｂに微小な窪みまたは突起をつけることにより形成することができる。また、光取り出し機構４０は、一面２０ａまたは出射面２０ｂに設けられた光散乱構造であってもよい。光散乱構造は、例えば、表面に光散乱粒子を配置すること、あるいは、表面に微細な凹凸構造を設けること等によって、作製することができる。 The light extraction mechanism 40 can be formed, for example, by attaching a minute depression or protrusion to the one surface 20a or the emission surface 20b of the light guide 20. The light extraction mechanism 40 may be a light scattering structure provided on the one surface 20a or the emission surface 20b. The light scattering structure can be produced, for example, by arranging light scattering particles on the surface or providing a fine uneven structure on the surface.
　光取り出し機構４０は、導光体２０中において全反射を繰り返して導光している光がその光取り出し機構４０に入射した場合に、その光の全反射条件を崩し、導光体２０から光を出射させる構造であればよい。本開示の一実施形態においては、導光体２０の一面２０ａに備えられた光入射部を構成する凹部３０よりも微細な凹部により、光取り出し機構４０が構成される。 The light extraction mechanism 40 breaks the total reflection condition of the light when light guided by repeating total reflection in the light guide 20 is incident on the light extraction mechanism 40, and the light is emitted from the light guide 20. Any structure that emits light may be used. In one embodiment of the present disclosure, the light extraction mechanism 40 is configured by a concave portion that is finer than the concave portion 30 that constitutes the light incident portion provided on the one surface 20 a of the light guide 20.
　図６には、凹部３０から入射し、導光体２０の内部を導光し、その後光取り出し機構４０から出射される光線１０４が図示されている。光線１０４が光取り出し機構４０に当たると、光取り出し機構４０における屈折や反射、または散乱等により、光線１０４の経路が曲げられる。その結果、光線１０４の少なくとも一部は、それ以上導光することができなくなり、導光体２０の外部へと出射される。 FIG. 6 shows a light beam 104 that enters from the recess 30, guides the inside of the light guide 20, and then exits from the light extraction mechanism 40. When the light beam 104 hits the light extraction mechanism 40, the path of the light beam 104 is bent due to refraction, reflection, scattering, or the like in the light extraction mechanism 40. As a result, at least a part of the light beam 104 can no longer be guided and is emitted to the outside of the light guide 20.
　なお、光取り出し機構４０によって、導光体２０の内部から一面２０ａの側に光が取り出される場合もある。しかし、この場合、取り出された光の多くは反射板１２で反射され、ふたたび導光体２０へ入射し、最終的には、導光体２０の出射面２０ｂから出射される。 The light extraction mechanism 40 may extract light from the inside of the light guide 20 toward the one surface 20a. However, in this case, most of the extracted light is reflected by the reflecting plate 12, enters the light guide 20 again, and finally exits from the exit surface 20 b of the light guide 20.
　光取り出し機構４０は、導光体２０の一面２０ａまたは出射面２０ｂの面内において、ランダムに配置されていてもよいし、周期的に配置されていてもよく、面内に分布構造をもつように配置されていてもよい。また、一面２０ａおよび出射面２０ｂの両方に備えられていてもよい。光取り出し機構４０は、取り出された光の輝度が均一になるよう、多数の光取り出し機構４０が配置される。一例としては、図３の上図に示すように、光取り出し機構４０は、光入射部３０に近いほど密度が低く、光入射部３０から離れるにしたがって密度が高くなるように配置される。それにより、各点光源１４を中心とした一定の領域毎に、点光源１４からの光の輝度が均一化されて出射される。 The light extraction mechanism 40 may be randomly arranged in the surface 20a or the emission surface 20b of the light guide 20, or may be periodically arranged, and has a distributed structure in the surface. May be arranged. Moreover, you may be provided in both the one surface 20a and the output surface 20b. The light extraction mechanism 40 includes a large number of light extraction mechanisms 40 so that the luminance of the extracted light is uniform. As an example, as shown in the upper diagram of FIG. 3, the light extraction mechanism 40 is arranged such that the density is lower as it is closer to the light incident part 30, and the density is higher as the distance from the light incident part 30 increases. As a result, the luminance of the light from the point light source 14 is made uniform and emitted for each fixed region centered on each point light source 14.
　また、光取り出し機構４０が凸部や微細な凹凸構造を有する場合は、それらの構造が、導光体２０と、反射板１２や拡散シート等の隣接する部材との密着を防止するためのスペーサを兼ねることもできる。 Further, when the light extraction mechanism 40 has a convex portion or a fine uneven structure, the structure prevents the light guide 20 from adhering to an adjacent member such as the reflector 12 or the diffusion sheet. It can also serve as.
　光取り出し機構４０が凹部または凸部により構成される場合、凹部または凸部の形状は、特に限定されず、四角錐状（ピラミッド形状）、半球状、円錐状、多角錐状、あるいは円錐台状、多角錐台状などであってもよい。 In the case where the light extraction mechanism 40 is configured by a concave portion or a convex portion, the shape of the concave portion or the convex portion is not particularly limited, and is a quadrangular pyramid shape, a hemispherical shape, a conical shape, a polygonal pyramid shape, or a truncated cone shape. It may be a polygonal frustum shape.
　また、光取り出し機構４０が凹部または凸部により構成される場合、面状照明装置を点灯した際に光取り出し機構４０の形状が視認されないようにするため、凹部または凸部の大きさは、平面視において点光源１４よりも小さいことが好ましい。具体的には、直径１μｍ～２００μｍの円からはみ出さない大きさであることが好ましい。 In addition, when the light extraction mechanism 40 is configured by a concave portion or a convex portion, the size of the concave portion or the convex portion is flat so that the shape of the light extraction mechanism 40 is not visually recognized when the planar lighting device is turned on. It is preferably smaller than the point light source 14 in view. Specifically, it is preferably a size that does not protrude from a circle having a diameter of 1 μm to 200 μm.
　光取り出し機構４０は、モールドを用いたインプリントや、射出成形等によって作製することができる。また、導光体２０の表面に、機械切削やレーザー加工により凹部を形成することによっても作製することができる。さらに、導光体２０の表面に、白色インキ等を印刷することによっても作製することができる。 The light extraction mechanism 40 can be manufactured by imprinting using a mold, injection molding, or the like. Moreover, it can also produce by forming a recessed part in the surface of the light guide 20 by mechanical cutting or laser processing. Furthermore, it can also be produced by printing white ink or the like on the surface of the light guide 20.
　設計変更例の導光体２１を備えたバックライトユニット３の断面模式図を図７に示す。図７においてはバックライトユニット２と同等の要素には同等の符号を付している。図７に示す導光体２１の凹部３０は、その底面３２が中央部に近付くにつれて入射面側に凸形状をなし、その凸形状の表面に反射層３３が形成されている。この場合、点光源１４から出射し、反射面３３ａに当たる光線の一部１０３は、反射面３３ａで反射されてその経路が導光体２０の面内方向に大きく曲げられる。したがって、反射面３３ａで反射された光線１０３が、光入射部３０の入射面３１へと入射する率を高め、かつ面内方向に導光する率を高めることができる。 7 is a schematic cross-sectional view of the backlight unit 3 including the light guide 21 according to the design change example. In FIG. 7, elements that are the same as those of the backlight unit 2 are denoted by the same reference numerals. The concave portion 30 of the light guide 21 shown in FIG. 7 has a convex shape on the incident surface side as the bottom surface 32 approaches the central portion, and a reflective layer 33 is formed on the convex surface. In this case, a part 103 of the light beam emitted from the point light source 14 and impinging on the reflection surface 33 a is reflected by the reflection surface 33 a and its path is greatly bent in the in-plane direction of the light guide 20. Therefore, the rate at which the light beam 103 reflected by the reflecting surface 33a is incident on the incident surface 31 of the light incident portion 30 can be increased, and the rate at which the light is guided in the in-plane direction can be increased.
　以下に実施例を挙げて、本開示の特徴をさらに具体的に説明する。なお、以下に示す材料、使用量、割合、処理内容、お処理手順等は、本開示の趣旨を逸脱しない限り、適宜、変更することができる。また、本開示の趣旨を逸脱しない限り、以下に示す構成以外の構成とすることもできる。 Hereinafter, the features of the present disclosure will be described more specifically with reference to examples. Note that the materials, amounts used, ratios, processing details, processing procedures, and the like shown below can be changed as appropriate without departing from the spirit of the present disclosure. Moreover, unless it deviates from the meaning of this indication, it can also be set as the structure other than the structure shown below.
［光源部１１の作製］
反射板としても機能する白色のプリント基板１２上に、点光源１５として青色発光ダイオードを縦に１０個および横に１０個、それぞれ５ｍｍ間隔で配置し、光源部１１とした。青色発光ダイオードとして、１５０μｍ×２５０μｍ×高さ１００μｍの大きさのものを用いた。光源部１１は以下の実施例および比較例において共通とした。 [Production of Light Source 11]
On the white printed circuit board 12 that also functions as a reflection plate, ten blue light emitting diodes as the point light source 15 and ten horizontal light emitting diodes are arranged at intervals of 5 mm to form the light source unit 11. A blue light emitting diode having a size of 150 μm × 250 μm × height 100 μm was used. The light source unit 11 is common in the following examples and comparative examples.
［実施例１］
　図９に実施例１の液晶表示装置３０１の概略構成を示す。 [Example 1]
FIG. 9 shows a schematic configuration of the liquid crystal display device 301 of the first embodiment.
［導光体２０１の作製］
　厚み５００μｍのアクリル板（日東樹脂工業株式会社製「クラレックス」）を準備し、一方の表面にＰＥＴフィルムからなる保護フィルムを貼合した。次に、保護フィルムの上から、機械切削により直径１０００μｍ、深さ４５０μｍの凹部３０を形成した。このとき、凹部３０は円柱状であり、凹部３０の側壁面３１はアクリル板の表面に対し垂直な円筒面であり、凹部３０の底面３２はアクリル板の表面に対し略水平な平面であった。同様の方法で、アクリル板の表面の、光源部１１の発光ダイオードの位置に対応する位置に、計１００個の凹部３０を設けた。 [Production of Light Guide 201]
An acrylic plate having a thickness of 500 μm (“Clarex” manufactured by Nitto Jushi Kogyo Co., Ltd.) was prepared, and a protective film made of a PET film was bonded to one surface. Next, a recess 30 having a diameter of 1000 μm and a depth of 450 μm was formed from above the protective film by mechanical cutting. At this time, the recessed part 30 was cylindrical, the side wall surface 31 of the recessed part 30 was a cylindrical surface perpendicular | vertical to the surface of an acrylic board, and the bottom face 32 of the recessed part 30 was a substantially horizontal plane with respect to the surface of an acrylic board. . In a similar manner, a total of 100 recesses 30 were provided on the surface of the acrylic plate at positions corresponding to the positions of the light emitting diodes of the light source unit 11.
　次に、保護フィルムを備えた面に、銀を８５ｎｍの厚みで蒸着し、さらにその上から、厚み２５０μｍの酸化ケイ素膜を蒸着した。保護フィルムをはがすと、銀および酸化ケイ素は凹部の側壁面３１にはほとんど付着せず、多くが凹部３０の底面３２に付着していた。銀膜および酸化ケイ素膜により反射層３３が形成され、この反射層３３が反射面を構成する。凹部３０の側壁面３１は光が入射する入射面である。 Next, silver was deposited in a thickness of 85 nm on the surface provided with the protective film, and a 250 μm thick silicon oxide film was deposited thereon. When the protective film was peeled off, silver and silicon oxide hardly adhered to the side wall surface 31 of the recess, and most adhered to the bottom surface 32 of the recess 30. A reflective layer 33 is formed by the silver film and the silicon oxide film, and this reflective layer 33 constitutes a reflective surface. The side wall surface 31 of the recess 30 is an incident surface on which light is incident.
　次に、アクリル板に形成した凹部３０の周囲に、ＣＯ２レーザー加工機を用いて、底面の直径１００μｍ、深さ１５０μｍの円錐状の窪み形状をなす光取り出し機構４０を形成した。光取り出し機構４０は、光入射部である凹部３０に近い位置では低密度で、光入射部から遠くなるにしたがい高密度になるように、１つの光入射部を中心とした領域につき約２０００個を形成した。さらに、それぞれの凹部３０の反射層３３上に、量子ドットを含む蛍光体層６０を積層した。蛍光体層６０は次のようにして積層した。量子ドットとしては、ＮＮ―ラボズ社製量子ドット「ＩＮＰ５３０」および「ＩＮＰ６５０」を用いた。それらの量子ドットを、それぞれ１０重量％の割合で、新中村化学工業株式会社製アクリレート「Ａ－ＮＯＤ－Ｎ」に分散し、さらに、ＢＡＳＦ社製光重合開始剤イルガキュア２９０を、１重量％の割合で混合した。この混合物を凹部３０の約１／２の体積を占めるように充填し、波長３６５ｎｍのＵＶ（Ｕｌｔｒａ　Ｖｉｏｌｅｔ）光により硬化した。これによって蛍光体層６０を形成した。
　以上のようにして、導光体２０１を作製した。 Next, a light extraction mechanism 40 having a conical depression shape with a bottom diameter of 100 μm and a depth of 150 μm was formed around the recess 30 formed in the acrylic plate using a CO 2 laser processing machine. The light extraction mechanism 40 has a low density at a position close to the concave portion 30 that is a light incident portion, and is about 2000 per region centered on one light incident portion so that the density increases as the distance from the light incident portion increases. Formed. Further, a phosphor layer 60 including quantum dots was laminated on the reflective layer 33 of each recess 30. The phosphor layer 60 was laminated as follows. As the quantum dots, quantum dots “INP530” and “INP650” manufactured by NN-Labs Co., Ltd. were used. These quantum dots are each dispersed in an acrylate “A-NOD-N” manufactured by Shin-Nakamura Chemical Co., Ltd. at a ratio of 10% by weight. Further, a photopolymerization initiator Irgacure 290 manufactured by BASF is added to 1% by weight. Mixed in proportion. This mixture was filled so as to occupy about ½ of the volume of the recess 30, and cured by UV (Ultra Violet) light having a wavelength of 365 nm. Thereby, the phosphor layer 60 was formed.
The light guide 201 was produced as described above.
［面状照明装置２２１の作製］
　導光体２０１を、それぞれの凹部３０が点光源１４を覆うように光源部１１に重ね、導光体２０１の出射面側にＡｐｐｌｅ社製タブレット端末ｉＰａｄ（登録商標）から取り出したプリズムシートおよび拡散シートを積層して、本実施例の面状照明装置２２１を作製した。 [Production of planar illumination device 221]
The light guide 201 is overlaid on the light source unit 11 so that each concave portion 30 covers the point light source 14, and the prism sheet taken out from the tablet terminal iPad (registered trademark) manufactured by Apple on the light emission surface side of the light guide 201 and the diffusion Sheets were stacked to produce the planar lighting device 221 of this example.
［液晶表示装置３０１の作製］
　Ａｐｐｌｅ社製タブレット端末ｉＰａｄ（登録商標）を分解し、バックライトと、液晶表示素子を取り出した。 [Production of Liquid Crystal Display Device 301]
The tablet terminal iPad (registered trademark) manufactured by Apple was disassembled, and the backlight and the liquid crystal display element were taken out.
　タブレット端末ｉＰａｄ（登録商標）のバックライトを、本実施例の面状照明装置２２１に換えて、図９に示す実施例１の液晶表示装置３０１を作製した。 The liquid crystal display device 301 of Example 1 shown in FIG. 9 was produced by replacing the backlight of the tablet terminal iPad (registered trademark) with the planar illumination device 221 of this example.
［実施例２］
　実施例１の導光体２０１において、凹部３０の底面３２に設けられる反射層３３の素材のうち銀をアルミニウムに変えた。それ以外は実施例１と同様にして、実施例２の液晶表示装置３０２を作製した。 [Example 2]
In the light guide 201 of Example 1, silver was changed to aluminum in the material of the reflective layer 33 provided on the bottom surface 32 of the recess 30. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 302 of Example 2. FIG.
［実施例３］
　実施例１の導光体２０１において、凹部３０の底面３２に設けられる反射層３３を誘電体多層膜に変えた。誘電体多層膜は、厚み４０μｍの酸化ケイ素膜と、厚み１００μｍの五酸化ニオブ膜とを、交互にそれぞれ１３層積層させて形成した。各層は、スパッタにより成膜形成した。それ以外は実施例１と同様にして、実施例３の液晶表示装置３０３を作製した。 [Example 3]
In the light guide 201 of Example 1, the reflective layer 33 provided on the bottom surface 32 of the recess 30 was changed to a dielectric multilayer film. The dielectric multilayer film was formed by alternately stacking 13 layers of silicon oxide films having a thickness of 40 μm and niobium pentoxide films having a thickness of 100 μm. Each layer was formed by sputtering. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 303 of Example 3. FIG.
［実施例４］
　図９に実施例４の液晶表示装置３０４の概略構成を示す。
　本実施例の導光体２０４は、実施例１の導光体２０１の製造方法において、機械切削に換えてＣＯ２レーザーにより凹部３０を形成した。この際、凹部３０の底面３２が、反射面の中央部に近づくにつれて一面側に凸形状をなすように形成した。凸形状の頂点は、凹部３０の最も深い位置から約１００μｍの距離になっていた。すなわち、本実施例において凹部３０の底面３２は、高さ１００μｍの円錐の円錐面により構成されている。導光体２０４を用いた以外は実施例１と同様にして面状照明装置２２４を作製し、図１０に示す実施例４の液晶表示装置３０４を作製した。 [Example 4]
FIG. 9 shows a schematic configuration of the liquid crystal display device 304 of the fourth embodiment.
In the light guide body 204 of this example, in the method for manufacturing the light guide body 201 of Example 1, the concave portion 30 was formed by a CO 2 laser instead of mechanical cutting. Under the present circumstances, it formed so that the bottom face 32 of the recessed part 30 might form a convex shape to one surface side as it approaches the center part of a reflective surface. The peak of the convex shape was a distance of about 100 μm from the deepest position of the concave portion 30. In other words, in the present embodiment, the bottom surface 32 of the recess 30 is constituted by a conical surface of a cone having a height of 100 μm. A planar illumination device 224 was produced in the same manner as in Example 1 except that the light guide 204 was used, and a liquid crystal display device 304 of Example 4 shown in FIG. 10 was produced.
［実施例５］
　実施例１の導光体２０１において、機械切削に換えてＣＯ２レーザーにより凹部３０を形成した。この際、凹部３０が四角柱の形状をなすように形成した。凹部の底面はアクリル板の入射面に対し略水平な平面であった。それ以外は実施例１と同様にして、実施例５の液晶表示装置３０５を作製した。 [Example 5]
In the light guide 201 of Example 1, the concave portion 30 was formed by a CO2 laser instead of mechanical cutting. At this time, the recess 30 was formed to have a quadrangular prism shape. The bottom surface of the recess was a substantially horizontal plane with respect to the incident surface of the acrylic plate. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device 305 of Example 5. FIG.
［比較例１］
　光源部１１の上に、拡散板として、日本ポリエステル株式会社製光拡散ポリカーボネート板「アロマブライト　ＫＴ‐１０７０Ｍ」を積層した。
　さらに、３Ｍ社製量子ドットシート「ＱＤＥＦ」を積層し、その上にタブレット端末ｉＰａｄ（登録商標）から取り出したプリズムシートおよび拡散シートを積層して、面状照明装置２３１を作製した。比較例１の面状照明装置２３１は導光体を備えていない。
　さらに、タブレット端末ｉＰａｄ（登録商標）のバックライトを、面状照明装置２３１に換えて、比較例１の液晶表示装置３１１を作製した。 [Comparative Example 1]
On the light source part 11, the light diffusion polycarbonate board "Aromabright KT-1070M" by Nippon Polyester Co., Ltd. was laminated | stacked as a diffusion plate.
Further, a quantum dot sheet “QDEF” manufactured by 3M was laminated, and a prism sheet and a diffusion sheet taken out from the tablet terminal iPad (registered trademark) were laminated thereon to produce a planar illumination device 231. The planar illumination device 231 of Comparative Example 1 does not include a light guide.
Furthermore, the backlight of the tablet terminal iPad (registered trademark) was replaced with the planar illumination device 231 to produce a liquid crystal display device 311 of Comparative Example 1.
［比較例２］
　図１０に比較例２の液晶表示装置３１２の概略構成を示す。 [Comparative Example 2]
FIG. 10 shows a schematic configuration of the liquid crystal display device 312 of Comparative Example 2.
［導光体２１２の作製］
　厚み５００μｍのアクリル板（日東樹脂工業株式会社製「クラレックス」）の一方の面に、機械切削により直径１０００μｍ、深さ４５０μｍの凹部３０を形成した。この際、凹部３０を光源部１１の点光源１５の位置に対応する位置に、計１００個設けた。凹部３０は円柱状であり、凹部３０の側壁面３１はアクリル板の表面に対し垂直であり、凹部３０の底面３２はアクリル板の表面に対し略水平な平面であった。 [Production of Light Guide 212]
A concave portion 30 having a diameter of 1000 μm and a depth of 450 μm was formed on one surface of an acrylic plate having a thickness of 500 μm (“Clarex” manufactured by Nitto Resin Co., Ltd.). At this time, a total of 100 recesses 30 were provided at positions corresponding to the positions of the point light sources 15 of the light source unit 11. The recessed part 30 was cylindrical, the side wall surface 31 of the recessed part 30 was perpendicular | vertical with respect to the surface of an acrylic board, and the bottom face 32 of the recessed part 30 was a substantially horizontal plane with respect to the surface of an acrylic board.
　次に、アクリル板の他方の面である出射面、すなわち、穴あけを行っていない面に、凹部３０に対応する位置に直径１２００μｍの穴を有するＰＥＴ保護フィルムを貼合した。保護フィルムを備えた面に、銀を８５ｎｍの厚みで蒸着し、さらにその上から、厚み２５０μｍの酸化ケイ素膜を蒸着した。保護フィルムをはがして、出射面側の、凹部３０に対応する位置に銀膜および酸化ケイ素膜からなる反射層３３が形成された導光体２１２を作製した。 Next, a PET protective film having a hole with a diameter of 1200 μm at a position corresponding to the concave portion 30 was bonded to the exit surface, that is, the surface not drilled, which is the other surface of the acrylic plate. Silver was vapor-deposited with a thickness of 85 nm on the surface provided with the protective film, and a silicon oxide film with a thickness of 250 μm was vapor-deposited thereon. The protective film was peeled off to produce a light guide body 212 in which a reflective layer 33 made of a silver film and a silicon oxide film was formed at a position corresponding to the concave portion 30 on the emission surface side.
［液晶表示装置３１２の作製］
　導光体２１２を用いた以外は実施例１と同様にして作製した面状照明装置２３２を用い、図１０に示す比較例２の液晶表示装置３１２を作製した。 [Production of Liquid Crystal Display 312]
A liquid crystal display device 312 of Comparative Example 2 shown in FIG. 10 was produced using a planar illumination device 232 produced in the same manner as in Example 1 except that the light guide 212 was used.
［比較例３］
　図１１に比較例３の液晶表示装置３１３の概略構成を示す。
　本実施例の導光体２１３は、実施例１の導光体２０１の製造方法において、凹部３０の側壁面３１が出射面となす角を６０度にし、凹部３０を円錐台形状とした以外は、実施例１と同様にして作製した。導光体２１３を用いた以外は実施例１と同様にして、面状照明装置２３３を作製し、図１１に示す比較例３の液晶表示装置３１３を作製した。 [Comparative Example 3]
FIG. 11 shows a schematic configuration of the liquid crystal display device 313 of Comparative Example 3.
The light guide 213 of the present embodiment is the same as the light guide 201 of the first embodiment except that the angle formed by the side wall surface 31 of the recess 30 with the exit surface is 60 degrees and the recess 30 has a truncated cone shape. This was produced in the same manner as in Example 1. A planar illumination device 233 was produced in the same manner as in Example 1 except that the light guide 213 was used, and a liquid crystal display device 313 of Comparative Example 3 shown in FIG. 11 was produced.
［比較例４］
　図１２に比較例４の液晶表示装置３１４の概略構成を示す。
　導光体２１４として、実施例１の導光体２０１において、蛍光体層６０を備えていないものを用いた。導光体２１４を、それぞれの凹部が発光ダイオードを覆うように光源部１１に重ね、導光体２１４の出射面側に、蛍光体シート２１５として３Ｍ社製量子ドットシート「ＱＤＥＦ」を積層した。さらに、蛍光体シート２１５の上にＡｐｐｌｅ社製タブレット端末ｉＰａｄ（登録商標）から取り出したプリズムシートおよび拡散シートを積層して、面状照明装置２３４を作製した。この面状照明装置２３４を用いて、図１２に示す比較例４の液晶表示装置３１４を作製した。 [Comparative Example 4]
FIG. 12 shows a schematic configuration of a liquid crystal display device 314 of Comparative Example 4.
As the light guide 214, the light guide 201 of Example 1 that does not include the phosphor layer 60 was used. The light guide body 214 was stacked on the light source unit 11 so that the respective concave portions covered the light emitting diodes, and a quantum dot sheet “QDEF” manufactured by 3M Company was stacked as the phosphor sheet 215 on the emission surface side of the light guide body 214. Further, a prism sheet and a diffusion sheet taken out from the tablet terminal iPad (registered trademark) manufactured by Apple were laminated on the phosphor sheet 215 to produce a planar illumination device 234. Using the planar lighting device 234, a liquid crystal display device 314 of Comparative Example 4 shown in FIG.
＜液晶表示装置の評価＞
［輝度の評価］
　作製した各液晶表示装置において、光源部１１の点光源１５に、それぞれ１０ｍＡの電流を流して点灯させ、液晶表示素子の画面全体を白色表示とし、株式会社トプコンテクノハウス社製分光放射計「ＳＲ－３」を用いて画面の輝度を測定した。光源部１１の中央３ｃｍ角に相当する範囲で、１０か所の輝度を測定し、輝度の平均値を算出した。結果を表１に示す。 <Evaluation of liquid crystal display device>
[Evaluation of brightness]
In each of the manufactured liquid crystal display devices, the point light source 15 of the light source unit 11 is turned on by supplying a current of 10 mA to make the entire screen of the liquid crystal display element display white, and a spectral radiometer “SR” manufactured by Topcon Technohouse Co., Ltd. -3 "was used to measure screen brightness. In the range corresponding to the central 3 cm square of the light source unit 11, the luminance at 10 locations was measured, and the average value of the luminance was calculated. The results are shown in Table 1.
［輝度均一性の評価］
　上記と同様にして、画面全体を白色表示とした液晶表示装置の画面輝度を、トプコンテクノハウス社製分光放射計「ＳＲ－３」を用いて測定した。このとき、光源部１１の中央３ｃｍ角に相当する範囲で、最も輝度が高い点の輝度を測定した。得られた最も高い輝度の値を、上記の平均輝度で除し、輝度の均一性を評価した。結果を表１に示す。 [Evaluation of luminance uniformity]
In the same manner as described above, the screen brightness of a liquid crystal display device in which the entire screen was displayed in white was measured using a spectroradiometer “SR-3” manufactured by Topcon Technohouse. At this time, the luminance of the point with the highest luminance was measured in the range corresponding to the central 3 cm square of the light source unit 11. The obtained highest luminance value was divided by the above average luminance to evaluate the luminance uniformity. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～５、および比較例１～３の面状照明装置は、いずれも、全体の厚みが１ｍｍ～２ｍｍの範囲にあり、薄いバックライトユニットであった。 The planar lighting devices of Examples 1 to 5 and Comparative Examples 1 to 3 were all thin backlight units having an overall thickness in the range of 1 mm to 2 mm.
　実施例１～５の面状照明装置は、いずれも、点光源の直上において強い光漏れが視認されず、比較例１～３の面状照明装置に比較して輝度の均一性が良好であった。そのため、得られた液晶表示装置においても、輝度の均一性が良好であった。 In each of the planar lighting devices of Examples 1 to 5, strong light leakage was not visually recognized immediately above the point light source, and the luminance uniformity was better than that of the planar lighting devices of Comparative Examples 1 to 3. It was. Therefore, even in the obtained liquid crystal display device, the luminance uniformity was good.
　実施例１の面状照明装置は、反射層の素材として銀を用いたため、アルミニウムを用いた実施例２の面状照明装置に比較して、高い平均輝度が得られていた。 Since the planar lighting device of Example 1 used silver as the material of the reflective layer, a higher average luminance was obtained compared to the planar lighting device of Example 2 using aluminum.
　実施例４の面状照明装置は、反射面を凸形状としたため、実施例１の面状照明装置に比較して、点光源直上の光漏れがさらに小さく、平均輝度も高かった。 Since the reflecting surface of the planar illumination device of Example 4 had a convex shape, light leakage directly above the point light source was smaller and the average luminance was higher than that of the planar illumination device of Example 1.
　実施例５の面状照明装置は、凹部を四角柱形状としたため、入射光の導光が面内で等方的でなく、一部、輝度の高い領域と、輝度の低い領域が見られた。 In the planar lighting device of Example 5, since the concave portion was formed in a quadrangular prism shape, the light guide of incident light was not isotropic in the surface, and a region with high luminance and a region with low luminance were partially observed. .
　比較例１の面状照明装置は、本開示の導光体を用いていないため、輝度が均一化されず、点光源の直上に強い光漏れが見られた。 Since the planar illumination device of Comparative Example 1 does not use the light guide of the present disclosure, the luminance is not uniformed, and strong light leakage is seen directly above the point light source.
　比較例２の面状照明装置は、光入射部の凹部の上面に反射層が付与されておらず、導光体の出射面に反射層が付与されている。そのため、光入射部の凹部の上面と、反射層との間から光が漏れ、点光源の直上に比較的強い光漏れが見られた。そのため、輝度均一性が低かった。 In the planar illumination device of Comparative Example 2, the reflective layer is not provided on the upper surface of the concave portion of the light incident portion, and the reflective layer is provided on the exit surface of the light guide. For this reason, light leaked from between the upper surface of the concave portion of the light incident portion and the reflective layer, and a relatively strong light leak was seen directly above the point light source. For this reason, the luminance uniformity was low.
　比較例３の面状照明装置は、光入射部の凹部の壁面が入射面に対し垂直ではないため、凹部の壁面に当たった光の一部は導光体に入射した後、導光せず、光漏れとなっていた。そのため、輝度均一性が低かった。 In the surface illumination device of Comparative Example 3, the wall surface of the concave portion of the light incident portion is not perpendicular to the incident surface, and therefore, a part of the light hitting the wall surface of the concave portion is not guided after being incident on the light guide. Was leaking light. For this reason, the luminance uniformity was low.
　比較例４の面状照明装置は、実施例１～５と同等の輝度均一性を有していた。一方、蛍光体シートを備えた分、実施例１～５よりも厚みが厚かった。 The surface illumination device of Comparative Example 4 had luminance uniformity equivalent to that of Examples 1-5. On the other hand, the thickness of the phosphor sheet was larger than that of Examples 1 to 5.
　以上、説明してきたように、本開示の面状照明装置および液晶表示装置は、薄型で、輝度ムラが少ない均一な照明光および画像表示を得ることができ、さらに、ローカルディミングも可能である。 As described above, the planar illumination device and the liquid crystal display device of the present disclosure are thin, can obtain uniform illumination light and image display with little luminance unevenness, and can also perform local dimming.
　本開示の面状照明装置は、上述した液晶表示装置におけるバックライトユニットとしてのみならず、看板、標識などのバックライト、室内灯などとしても用いることが可能である。 The planar illumination device of the present disclosure can be used not only as a backlight unit in the above-described liquid crystal display device but also as a backlight of a signboard, a sign, etc., a room light, and the like.
　２０１８年５月１８日に出願された日本国特許出願２０１８－０９６５７１号の開示は、その全体が参照により本明細書に取り込まれる。
　本明細書に記載された全ての文献、特許出願、および技術規格は、個々の文献、特許出願、および技術規格が参照により取り込まれることが具体的かつ個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 The disclosure of Japanese Patent Application No. 2018-096571 filed on May 18, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims (11)

  1. 　複数の凹部を備えた一面、および光を出射する出射面を備えた板状の導光体であって、内部で導光される光を反射、屈折あるいは散乱させる光取出し機構を有する導光体と、
    　各々の少なくとも一部が前記複数の凹部の各々に収容される複数の点光源を有する光源部とを備え、
    　前記複数の凹部の各々は、前記出射面に対して垂直であり、かつ、前記点光源からの光を前記導光体内に入射させる入射面と、前記点光源に対向し、かつ、前記点光源からの光を反射する反射面とを有し、
    　前記複数の凹部の各々が、前記反射面と前記点光源との間に、前記点光源と離隔して配置された蛍光体を備えた面状照明装置。     A light guide having a light extraction mechanism that reflects, refracts, or scatters light guided inside, one plate having a plurality of recesses and an emission surface that emits light. When,
    A light source unit having a plurality of point light sources each of which is housed in each of the plurality of recesses,
    Each of the plurality of recesses is perpendicular to the exit surface, and is an entrance surface that allows light from the point light source to enter the light guide body, and faces the point light source, and the point light source And a reflecting surface that reflects light from
    Each of the plurality of concave portions is a planar illumination device including a phosphor that is disposed between the reflection surface and the point light source so as to be separated from the point light source.
  2. 　前記蛍光体が、少なくとも緑色を発光する蛍光体と赤色を発光する蛍光体とを含む請求項１に記載の面状照明装置。 The planar illumination device according to claim 1, wherein the phosphor includes at least a phosphor that emits green light and a phosphor that emits red light.
  3. 　前記蛍光体が、量子ドットを含む、請求項１または２に記載の面状照明装置。 The planar illumination device according to claim 1 or 2, wherein the phosphor includes quantum dots.
  4. 　前記点光源が近紫外発光ダイオード、または青色発光ダイオードである、請求項１から３のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 3, wherein the point light source is a near ultraviolet light emitting diode or a blue light emitting diode.
  5. 　前記複数の点光源の各々が、前記各々の凹部の前記反射面に向けて光を出射する請求項１から４のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 4, wherein each of the plurality of point light sources emits light toward the reflection surface of each of the recesses.
  6. 　前記入射面が、円筒面である請求項１から５のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 5, wherein the incident surface is a cylindrical surface.
  7. 　前記反射面が金属薄膜からなる、請求項１から６のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 6, wherein the reflecting surface is made of a metal thin film.
  8. 　前記金属薄膜が少なくとも銀を含んでなる、請求項７に記載の面状照明装置。 The planar illumination device according to claim 7, wherein the metal thin film contains at least silver.
  9. 　前記反射面が誘電体多層膜からなる、請求項１から６のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 6, wherein the reflecting surface is made of a dielectric multilayer film.
  10. 　前記反射面が、該反射面の中央部に近付くにつれて前記一面側に凸形状をなす、請求項１から９のいずれか１項に記載の面状照明装置。 The planar illumination device according to any one of claims 1 to 9, wherein the reflective surface has a convex shape toward the one surface as it approaches the center of the reflective surface.
  11. 　液晶表示素子と、
    　請求項１から１０のいずれか１項に記載の面状照明装置とを備えた液晶表示装置。     A liquid crystal display element;
    A liquid crystal display device comprising the planar illumination device according to claim 1.
PCT/JP2019/019954 2018-05-18 2019-05-20 Planar illumination device and liquid crystal display device WO2019221304A1 (en)

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