JP5332469B2 - Optical component, backlight unit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deformation of an optical component due to heat from a light source, and/or eliminate or prevent a lamp image. <P>SOLUTION: The optical component includes a multilayer diffusion layer 12 comprising: a transparent resin layer 11 including a light incidence surface on which light emitted from the light source is made incident, and a light emission surface from which the light made incident on the light incidence surface is emitted; and a back diffusion layer 10 which covers the light incidence surface and includes transparent resin, a plurality of holes distributed in the transparent resin, and a plurality of transparent particles having a refractive index different from that of the transparent resin. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to display technology.

  Patent Document 1 describes an optical component used in a backlight unit of a liquid crystal display device. This optical component includes an optical functional layer having a plurality of convex portions each constituting a lens provided on the front surface, a diffusion layer facing the back surface, and a reflective layer interposed therebetween. . The reflection layer is provided with an opening at a position corresponding to the central portion of the lens.

  When the diffusion layer of this optical component is illuminated, the diffusion layer emits scattered light. Of this scattered light, light traveling toward the center of the lens is incident on the optical functional layer, and light traveling toward the peripheral edge of the lens is reflected by the reflective layer. The scattered light reflected by the reflective layer changes its traveling direction by being further scattered by the diffusion layer, and finally enters the optical functional layer. Scattered light that has entered the optical functional layer is emitted from the optical functional layer with a spreading angle controlled by a lens.

  As is clear from this, the reflective layer suppresses the incidence of scattered light on the periphery of the lens. Therefore, this optical component emits less light to the wide-angle side due to reflection at the interface between the peripheral edge of the lens and the air layer. Further, as described above, the light reflected by the reflective layer finally enters the central portion of the lens. Therefore, when this optical component is used, desired directivity and high light utilization efficiency can be achieved.

By the way, many large liquid crystal display devices use a direct type backlight unit including a plurality of cold cathode tubes or LEDs (light-emitting diodes) as a light source. When a direct type backlight unit is used, a bright display is possible over the entire screen.
JP 2007-213035 A

  Liquid crystal display devices tend to be thinner. Therefore, the direct type backlight unit is required to reduce the thickness of the optical components used in the backlight unit and to reduce the distance between the components. When the distance between the light source and the optical component is shortened, the optical component is likely to be deformed, for example, warped. Also, if the distance between the light source and the optical component is shortened, the light emitted from the light source enters the optical component before it sufficiently spreads, so the luminance distribution of the backlight body may greatly affect the image.

  An object of the present invention is to provide a technique capable of suppressing deformation of an optical component due to heat from a light source and / or suppressing or preventing a lamp image.

According to the first aspect of the present invention, a transparent resin layer including a light incident surface on which light emitted from a light source is incident, a light emitting surface that emits light incident on the light incident surface, and the light incident surface are covered. The first transparent resin, the plurality of first holes distributed in the first transparent resin, and the plurality of first holes distributed in the first transparent resin and having a refractive index different from that of the first transparent resin. A back diffusion layer including transparent particles; a second transparent resin that covers the light emitting surface; and a plurality of second holes distributed in the second transparent resin; and distributed in the second transparent resin. And a multilayer diffusion layer comprising a front diffusion layer including a plurality of second transparent particles having a refractive index different from that of the second transparent resin, and the volume of the first transparent resin and the plurality of first transparent resins. The ratio of the volume of the plurality of first holes to the sum of the volume of the particles, and the volume of the second transparent resin and the plurality of the plurality of holes The ratio of the volume of the plurality of second pores to the sum of the volume of two transparent particles is in the range of 40% to 80%, and the thickness of the back diffusion layer with respect to the thickness of the transparent resin layer The ratio of the thickness of the front diffusion layer to the thickness of the back diffusion layer is in the range of 1/3 to 1 and heated to 80 ° C. An optical component is provided in which the maximum warpage amount is less than 2% of the long side .

According to a second aspect of the present invention, there is provided a backlight unit comprising the optical component according to the first aspect and a light source for proving the optical component.

According to a third aspect of the present invention, there is provided a display device comprising the backlight unit according to the second aspect and a display panel facing the light source with the optical component interposed therebetween.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which makes it possible to suppress the deformation | transformation of the optical component by the heat from a light source, and / or to suppress or prevent a lamp image is provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same referential mark is attached | subjected to the component which exhibits the same or similar function through all the drawings, and the overlapping description is abbreviate | omitted.

FIG. 1 is a cross-sectional view schematically showing an optical component according to an aspect of the present invention.
The optical component shown in FIG. 1 includes a multilayer diffusion layer 12. When this optical component is used in a display device, the handling property at the time of assembling the display device, that is, the demand for high rigidity and thinning is taken into consideration, the thickness of the multilayer diffusion layer 12 is, for example, 1.5 mm to 2 mm. Within the range of

  The multilayer diffusion layer 12 includes a pair of diffusion layers 10 and a transparent resin layer 11 interposed therebetween.

  The transparent resin layer 11 includes a light incident surface on which light emitted from a light source (not shown) is incident, and a light emitting surface that emits light incident on the light incident surface. In FIG. 1, as an example, the lower surface and the upper surface of the transparent resin layer 11 are a light incident surface and a light emission surface, respectively.

  The transparent resin layer 11 is made of a transparent resin, typically a colorless and transparent resin. Examples of the transparent resin include acrylic resin, PS (polystyrene) resin, MS (methacrylstyrene styrene copolymer) resin, PC (polycarbonate) resin, AS (acrylonitrile styrene copolymer) resin, or COP (cycloolefin polymer). ) Can be used.

  The thickness of the transparent resin layer 11 is, for example, in the range of 1.0 mm to 1.8 mm. When the transparent resin layer 11 is excessively thinned, the multilayer diffusion layer 12 is easily deformed. If the transparent resin layer 11 is excessively thick, it is difficult to obtain a thin multilayer diffusion layer 12.

  The diffusion layer 10 covers the light incident surface and the light emission surface of the transparent resin layer 11. These diffusion layers 10 are integrated with the transparent resin layer 11. For example, each of these diffusion layers 10 is bonded to the transparent resin layer 11 using, for example, an adhesive or an adhesive, or is bonded to the transparent resin layer 11 by a room temperature bonding process using an excimer laser. .

  The diffusion layer 10 covering the light incident surface of the transparent resin layer 11, that is, the back diffusion layer 10, is a layer having high heat insulation in addition to light diffusibility. The back diffusion layer 10 includes a transparent resin, pores, and transparent particles.

  The transparent resin is, for example, a thermoplastic resin. Examples of the thermoplastic resin include polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, cyclohexanedimethanol copolymer polyester resin, isophthalic acid copolymer polyester resin, spiroglycol copolymer polyester resin, and fluorene. Polyester resins such as copolyester resins, polyolefin resins such as polyethylene, polypropylene, polymethylpentene and alicyclic olefin copolymer resins, acrylic resins such as polymethyl methacrylate, polycarbonate, polystyrene, polyamide, polyether, polyesteramide, poly Ether ester, polyvinyl chloride, cycloolefin polymer, copolymer containing these as components, or this It is possible to use a mixture of resins.

  The pores are almost uniformly distributed in the transparent resin. The pores can be obtained, for example, by forming a layer containing the above thermoplastic resin and transparent particles dispersed therein, and stretching the layer uniaxially or biaxially while heating appropriately. That is, by stretching this layer while heating appropriately, a gap is formed between the thermoplastic resin and the transparent particles, and this gap can be used as a void.

  The transparent particles are distributed almost uniformly in the transparent resin. As the transparent particles, for example, inorganic particles such as titanium oxide and barium sulfate can be used. Alternatively, resin particles that are incompatible with the thermoplastic resin may be used as the transparent particles as long as they are sufficiently harder than the thermoplastic resin at the time of stretching. As the material of the resin particles, for example, acrylic resin, polycarbonate, polystyrene, polyamide, or polyether can be used.

  As the transparent particles, those having an average particle diameter in the range of, for example, 1 μm to 30 μm are used.

  The amount of the transparent particles added to the transparent resin is determined in consideration of, for example, the ratio of the volume of the pores to the volume of the back diffusion layer 10.

  The ratio of the volume of the pores to the sum of the volume of the transparent resin and the volume of the transparent particles is, for example, in the range of 40% to 80%. If this ratio is excessively increased, the light diffusing ability decreases. If this ratio is excessively reduced, the light diffusing ability is lowered, the heat insulating property is lowered, and the multilayer diffusion layer 12 and / or a layer installed on the front side thereof is likely to be warped when the light source is turned on.

  The ratio of the thickness of the back diffusion layer 10 to the thickness of the transparent resin layer 11 is, for example, in the range of 1/18 to 1/6, and typically in the range of 1/9 to 1/6. Further, the thickness of the back diffusion layer 10 is set in a range of, for example, 125 μm to 333 μm. When the back diffusion layer 10 is excessively thinned, it is difficult to obtain high heat insulating properties. If the back diffusion layer 10 is excessively thick, the multilayer diffusion layer 12 itself tends to warp.

  The diffusion layer 10 covering the light emission surface of the transparent resin layer 11, that is, the front diffusion layer 10 is a layer having light diffusibility. The front diffusion layer 10 includes a transparent resin and transparent particles.

  As the transparent resin and transparent particles of the front diffusion layer 10, for example, the same materials as those described above for the back diffusion layer 10 can be used.

  The transparent resin and the transparent particles included in the front diffusion layer 10 may be the same as or different from the transparent resin and the transparent particles included in the back diffusion layer 10, respectively. For example, the front diffusion layer 10 and the back diffusion layer 10 may have the same transparent resin type, transparent resin content, transparent particle material, transparent particle average particle size, and transparent particle content. , One or more of them may be different.

  The front diffusion layer 10 may have high heat insulating properties similarly to the back diffusion layer 10. That is, the front diffusion layer 10 may further include holes. The holes in the front diffusion layer 10 can be formed by the same method as described for the back diffusion layer 10.

  When the front diffusion layer 10 includes holes, the ratio of the volume of the holes to the sum of the volume of the transparent resin and the volume of the transparent particles is, for example, 80% or less, as in the case of the back diffusion layer 10. Is in the range of 40% to 80%. If this ratio is excessively increased, the light diffusing ability decreases. When this ratio is excessively reduced, the light diffusing ability is lowered, and the heat insulating property is lowered.

  The ratio of the thickness of the back diffusion layer 10 to the thickness of the transparent resin layer 11 is, for example, within a range of 1/12 to 1/6, and typically within a range of 1/9 to 1/6. Further, the thickness of the back diffusion layer 10 is set in a range of, for example, 125 μm to 333 μm. When the back diffusion layer 10 is excessively thinned, it is difficult to obtain high heat insulating properties. If the back diffusion layer 10 is excessively thick, the multilayer diffusion layer 12 itself tends to warp.

  When the thickness of the front diffusion layer 10 is changed, the heat insulation property, light diffusion capability, and thermal stability of the multilayer diffusion layer 12, that is, the difficulty of warping when heat is applied, change. The thickness of the front diffusion layer 10 is, for example, substantially equal to or thinner than the thickness of the back diffusion layer 10. For example, the ratio of the thickness of the front diffusion layer 10 to the thickness of the back diffusion layer 10 is in the range of 6/19 to 1. Further, the thickness of the front diffusion layer 10 is, for example, in the range of 39.5 μm to 333 μm.

The front diffusion layer 10 may be omitted as described below.
FIG. 2 is a cross-sectional view schematically showing a modification of the optical component shown in FIG.
The optical component shown in FIG. 2 includes a multilayer diffusion layer 13. The multilayer diffusion layer 13 is the same as the multilayer diffusion layer 12 except that the front diffusion layer 10 is not included. That is, the multilayer diffusion layer 13 includes the transparent resin layer 11 and the back diffusion layer 10. When the structure shown in FIG. 2 is adopted, the ratio of the thickness of the back diffusion layer 10 to the thickness of the transparent resin layer 11 is, for example, in the range of 1/9 to 1/3.

  The multilayer diffusion layer 12 shown in FIG. 1 and the multilayer diffusion layer 13 shown in FIG. 2 can be combined with other optical elements. Hereinafter, an example in which the multilayer diffusion layer 12 shown in FIG. 1 is combined with another optical element will be described. However, the multilayer diffusion layer 12 can be replaced with the multilayer diffusion layer 13 shown in FIG.

FIG. 3 is a cross-sectional view schematically showing another modification of the optical component shown in FIG.
The optical component shown in FIG. 3 includes a multilayer diffusion layer 12 and an optical sheet 9.

  The optical sheet 9 is fixed on the front diffusion layer 10 of the multilayer diffusion layer 12. The optical sheet 9 includes a lens array 5, a light transmissive substrate 6, an adhesive layer 7, and a mask layer 8.

  The lens array 5 is a relief layer in which one main surface faces the multilayer diffusion layer 12 and a plurality of convex portions each constituting a lens are provided on the other main surface. These lenses are, for example, a plurality of lenticular or cylindrical lenses arranged in the width direction, or a plurality of hemispherical lenses arranged in the vertical direction and the horizontal direction. At least some of these lenses may have a concave top.

  These convex parts may not constitute a lens. For example, some or all of these convex portions may constitute a prism.

  The lens array 5 is obtained, for example, by applying a radiation curable resin such as an ultraviolet curable resin on the light transmissive substrate 6 and irradiating the coating film with radiation such as ultraviolet rays while embossing. Alternatively, the lens array 5 is formed by an injection molding method or a hot press molding method using a thermoplastic resin or a thermosetting resin such as polyethylene terephthalate, polycarbonate, polymethyl methacrylate, cycloolefin polymer and acrylonitrile styrene copolymer. You can also.

  The light transmissive substrate 6 is interposed between the lens array 5 and the multilayer diffusion layer 12. The light transmissive substrate 6 supports the lens array 5.

  The light transmissive substrate 6 is typically made of a transparent material such as a transparent resin. The light transmissive substrate 6 may have light scattering properties.

  As a material of the light transmissive substrate 6, for example, a thermoplastic resin or a thermosetting resin can be used. As the thermoplastic resin or thermosetting resin, for example, polystyrene, polycarbonate, methacryl-styrene copolymer, acrylonitrile-styrene copolymer, or polyethylene terephthalate can be used. The material of the light transmissive substrate 6 may be the same as or different from the material of the lens array 5.

  The adhesive layer 7 is light transmissive and typically transparent. The adhesive layer 7 joins the light transmissive substrate 6 and the mask layer 8 together. When the mask layer 8 is formed on the light transmissive substrate 6, the adhesive layer 7 can be omitted.

  The mask layer 8 is interposed between the adhesive layer 7 and the multilayer diffusion layer 12. The mask layer 8 is opened at a position corresponding to the center of each lens included in the lens array 5. The mask layer 8 forms a gap between the adhesive layer 7 and the multilayer diffusion layer 12 at a position corresponding to the opening. The mask layer 8 transmits light traveling toward the top of the lens and the vicinity thereof out of light emitted from the multilayer diffusion layer 12 forward, and reflects or absorbs light traveling toward the boundary between adjacent lenses. To do.

  As a material of the mask layer 8, for example, a light shielding material can be used. As the light shielding material, it is preferable to use a metal reflective material or a white material such as titanium dioxide. In this way, the light reflected by the mask layer 8 is further scattered by the multilayer diffusion layer 12 and the like, and changes its traveling direction, and finally enters the lens array 5.

  The mask layer 8 can be formed on the light transmissive substrate 6, for example. For example, when the lens array 5 is illuminated from the front side, a light intensity distribution corresponding to the arrangement of the lenses is generated on the back side of the light transmissive substrate 6. For example, if this light intensity distribution is used for photolithography, the mask layer 8 can be formed without using a photomask.

  In addition, the multilayer diffused layer 12 and the optical sheet 9 can be integrated by bonding those edges together via a double-sided tape, for example. Alternatively, the multilayer diffusion layer 12 and the optical sheet 9 may be bonded together using an adhesive or a pressure-sensitive adhesive. As the adhesive or pressure-sensitive adhesive, for example, urethane, acrylic, rubber, silicone, or vinyl resins can be used. The pressure-sensitive adhesive or adhesive may be a one-component type. In this case, the pressure-sensitive adhesive or adhesive may be bonded by pressing, or may be cured by heat or light. The adhesive or pressure-sensitive adhesive may be a two-component type. For example, the adhesive or pressure-sensitive adhesive may be a mixture of a plurality of liquids and cured.

  Alternatively, the multilayer diffusion layer 12 and the optical sheet 9 may be used in a backlight unit without being integrated. In this case, the optical component is composed of the multilayer diffusion layer 12.

FIG. 4 is a cross-sectional view schematically showing still another modification of the optical component shown in FIG.
The optical component shown in FIG. 4 includes a multilayer diffusion layer 12 and a lens array 14. The lens array 14 is provided on the front diffusion layer 10 of the multilayer diffusion layer 12.

  The lens array 14 includes, for example, a plurality of lenticular or cylindrical lenses each having a concave top and arranged in the width direction, or a plurality of hemispherical lenses each having a concave top and arranged vertically and horizontally. These lenses may not have a concave top.

  FIG. 5 is a cross-sectional view schematically showing still another modification of the optical component shown in FIG. 6 is an enlarged perspective view showing a part of the optical component shown in FIG.

  The optical component shown in FIG. 5 includes a multilayer diffusion layer 12 and a prism array 15. The prism array 15 is provided on the front diffusion layer 10 of the multilayer diffusion layer 12.

  Each prism array 15 has a shape extending in one direction, and includes a plurality of prisms arranged in the width direction. As shown in FIG. 6, each prism 15 a is a triangular prism provided with a plurality of V-shaped grooves each crossing one of the sides connecting the two bottom surfaces. These prisms may not be provided with V-shaped grooves. In the optical component shown in FIG. 3, the prism array 15 described with reference to FIGS. 5 and 6 may be used instead of the lens array 5.

  When the optical component described above is used in a display device including a backlight unit, the light source included in the backlight unit may be destroyed if the back surface of the optical component is warped so as to be convex. On the contrary, if this optical component is warped so that its front surface is convex, the display panel may be destroyed. Therefore, it is desirable that this optical component has a small maximum warpage, for example, less than 2% of the long side.

  The “maximum warpage amount” is measured by the following method. First, the optical component is placed on a hot plate with its front face facing upward, and is heated to 80 ° C. And the average of the distance from the mounting surface of the four corners of an optical component is calculated | required, keeping temperature constant. Thereafter, the optical component is sufficiently cooled, and the same measurement as described above is performed except that the optical component is placed on the hot plate so that the back surface thereof faces upward. The “maximum warpage amount” is the maximum value obtained in this way.

The optical component described above can be used in a backlight unit, for example.
FIG. 7 is a plan view schematically showing an example of the backlight unit.

  The backlight unit shown in FIG. 7 includes a backlight body and optical components. Here, the optical component shown in FIG. 3 is used as an example, but other optical components may be used.

  The backlight body includes a plurality of light sources 16, a reflective layer 17, and a support not shown. The light source 16 and the reflective layer 17 are supported by a support.

  As the light source 16, for example, a point light source such as an LED can be used. Other light sources such as a linear light source may be used as the light source 16. For example, a fluorescent lamp or a cold cathode fluorescent lamp (CCFL) can be used as the line light source.

  The reflective layer 17 faces the back surface of the optical component with the light source 16 therebetween. Typically, the reflective layer 17 has a bowl shape. The reflective layer 17 is a light reflective film or sheet, for example, a white film or sheet. The reflective layer 17 may be a layer formed on a support such as a metal plate.

  In the backlight body, the light source 16 emits light in almost all directions. The reflective layer 17 reflects light emitted backward from the light source 16 to the front. When the reflective layer 17 has a bowl shape as shown in FIG. 7, the light emitted from the light source 16 to the side is reflected forward. Therefore, the backlight main body advances almost all of the light emitted from the light source 16 forward.

This backlight unit can be used, for example, in a display device.
FIG. 8 is a cross-sectional view schematically showing an example of the display device.

  The display device shown in FIG. 8 includes a display panel 18 and a backlight unit. The backlight unit is installed on the back side of the display panel 18 and illuminates the back side of the display panel 18. Here, as an example, the backlight unit shown in FIG. 7, that is, the backlight unit including the optical components shown in FIG. 3 is used, but the backlight unit including other optical components may be used. Good.

  The display panel 18 includes, for example, a liquid crystal cell and a pair of polarizing plates (polarizing film). The liquid crystal cell includes, for example, a pair of glass substrates and a liquid crystal layer sandwiched between them. The polarizing plates are attached to the front surface and the back surface of the liquid crystal cell, respectively.

  The display panel 18 is a transmissive display panel in this aspect, but may be a transflective display panel. That is, the display device may be a transflective liquid crystal display device.

  Alternatively, another display panel may be used instead of the display panel 18 including the liquid crystal cell. For example, a display panel that displays a still image with a light-transmitting colored pattern may be used.

  This display device uses the optical component described above. Therefore, even if the distance between the light source 16 and the optical component is shortened, the optical component is hardly deformed, for example, warped. That is, the above optical component is advantageous for thinning the display device.

  Further, this optical component includes, in particular, the multilayer diffusion layer 12 shown in FIG. 1 or the multilayer diffusion layer 13 shown in FIG. 2, the lens array 5 shown in FIG. 3, the lens array 14 shown in FIG. 4, and the prism array shown in FIG. If a structure combined with a relief layer such as 15 is adopted, for example, both high front luminance and high diffusion performance are achieved. Therefore, for example, when a monochromatic image such as a white image is displayed on the display device shown in FIG. 8, in addition to achieving an optimum viewing angle, luminance variations corresponding to the arrangement of the lamps 16 are perceived by the observer. That is, the lamp image is rarely close to the viewer.

Examples of the present invention will be described below.
<Manufacture of optical components A1 to A8>
The optical component shown in FIG. 3 was manufactured by the following method.

  First, a polyethylene terephthalate chip, a poly-4-methylpentene-1 chip which is an incompatible thermoplastic resin, and a polyethylene glycol having a molecular weight of 4000 which is a dispersant are mixed together. It was subjected to vacuum drying at 180 ° C. for 3 hours. Thereafter, this was supplied to an extruder, melted at 285 ° C. by a conventional method, and introduced into a T-die composite die to obtain a melt sheet. The obtained melt sheet was cooled and solidified while being in close contact with a cooling drum whose surface temperature was maintained at 25 ° C. to obtain an unstretched film.

  Subsequently, the unstretched film was stretched in the longitudinal direction using a roll group heated to 98 ° C., and then cooled in a roll group at 25 ° C. to obtain a uniaxially stretched film.

  Next, this uniaxially stretched film was guided to a tenter while being held by a clip, and stretched in a direction perpendicular to the longitudinal direction in a heated atmosphere at 105 ° C. Next, this was relaxed in the width direction, subjected to a heat treatment at 220 ° C. in a tenter, and then uniformly cooled. Finally, this was wound up to obtain the back and front diffusion layers 10.

  Here, diffusion layers 10 having different thicknesses and bubble contents were formed by changing the amount of poly-4-methylpentene-1 added and the stretching ratio. Further, each diffusion layer 10 was subjected to easy adhesion treatment on one surface and subjected to light resistance treatment and low heat shrinkage treatment on the other surface.

  The diffusion layer 10 thus obtained was attached to both surfaces of the transparent resin layer 11 made of polystyrene resin so that the surfaces subjected to the easy adhesion treatment face each other using an adhesive. In this way, a multilayer diffusion layer 12 was obtained. Note that the thickness of the multilayer diffusion layer 12 formed here was 2 mm.

  Next, each of the multilayer diffusion layers 12 and the optical sheet 9 were bonded together with an adhesive so that the front diffusion layer 10 faced the mask layer 8. As described above, optical components A1 to A8 shown in Table 1 below were obtained.

  In Table 1, the heading “ratio of thickness” is attached, and the column of “back” describes the ratio of the thickness of the transparent resin layer 11 to the thickness of the back diffusion layer 10. . Then, the heading “ratio of thickness” is attached, and the column labeled “front surface” describes the ratio of the thickness of the transparent resin layer 11 to the thickness of the front diffusion layer 10. Further, in the column labeled “Bubble volume ratio”, the ratio of the pore volume to the sum of the volume of the transparent resin and the volume of the transparent particles in the back diffusion layer 10, that is, the pores of the back diffusion layer 10. The ratio of the void volume to the volume excluding is described.

<Manufacture of optical components B1 to B9>
Optical components B1 to B9 shown in Table 1 below were manufactured by the same method as described above with respect to the optical components A1 to A8 except that the front diffusion layer 10 was omitted. That is, a multilayer diffusion layer 13 shown in FIG. 2 was formed instead of the multilayer diffusion layer 12 shown in FIG. In all of the optical components B1 to B9, the thickness of the multilayer diffusion layer 13 was 2 mm.

<Manufacture of optical components C1 and C2>
Optical components C1 and C2 shown in Table 1 below were manufactured by the same method as described above with respect to the optical components A1 to A8, except that the back and front diffusion layers 10 were formed without performing the stretching treatment. That is, no holes were provided in the back and front diffusion layers 10. In any of the optical components C1 and C2, the thickness of the multilayer diffusion layer 12 was 2 mm. The optical components C1 and C2 are the same except that the multilayer diffusion layer 12 and the optical sheet 9 are not integrated in the optical component C1, and the multilayer diffusion layer 12 and the optical sheet 9 are integrated in the optical component C2. It is.

<Performance evaluation>
For each of the optical components A1 to A8, B1 to B9, and C1 and C2, the maximum warpage amount was measured by the method described above.

Also, the display device described with reference to FIG. 8, here, a liquid crystal display device, was manufactured using each of the optical components A1 to A8, B1 to B9, and C1 and C2. A white image was displayed on these liquid crystal display devices, and the front luminance and ease of visual recognition of the lamp image were examined.
These results are summarized in Table 1 below.

  In Table 1, the symbols “◯” and “x” in the column “Lamp Image” indicate that the lamp image was not visually recognized and visually recognized. The symbols “◯”, “Δ”, and “×” in the “Front luminance” column indicate that the front luminance is equal to or higher than the first reference value, the front luminance is lower than the first reference value, and It indicates that the value is higher than 2 reference values (> first reference value), and the front luminance is equal to or lower than the second reference value. Furthermore, the “maximum warpage amount (%)” represents the ratio of the maximum warpage amount measured by the above-described method to the length of the long side of the sample.

As shown in Table 1, the maximum warpage amount of the optical components A1 to A8 and B1 to B9 was significantly reduced as compared with the optical components C1 and C2. It was also confirmed that the lamp image was difficult to see.
The invention described in the original claims is appended below.
[1]
A transparent resin layer including a light incident surface on which light emitted from a light source is incident and a light emitting surface that emits light incident on the light incident surface;
The light incident surface is covered, and includes a transparent resin, a plurality of holes distributed in the transparent resin, and a plurality of transparent particles distributed in the transparent resin and having a refractive index different from that of the transparent resin. Back diffusion layer and
An optical component comprising a multilayer diffusion layer comprising:
[2]
The ratio of the volume of the plurality of pores to the sum of the volume of the transparent resin and the volume of the plurality of transparent particles is in the range of 40% to 80%, and the optical according to [1] parts.
[3]
[2] The optical component according to [2], wherein the ratio of the thickness of the back diffusion layer to the thickness of the transparent resin layer is in the range of 1/9 to 1/3.
[4]
A transparent resin layer including a light incident surface on which light emitted from a light source is incident and a light emitting surface that emits light incident on the light incident surface;
A first transparent resin, a plurality of first holes distributed in the first transparent resin, distributed in the first transparent resin, covering the light incident surface, and the first transparent resin has a refractive index A back diffusion layer including a plurality of first transparent particles having different from each other;
A front diffusion layer that covers the light emitting surface and includes a second transparent resin and a plurality of second transparent particles distributed in the second transparent resin and having a refractive index different from that of the second transparent resin;
An optical component comprising a multilayer diffusion layer comprising:
[5]
The optical component according to [4], wherein the front diffusion layer further includes a plurality of second holes distributed in the second transparent resin.
[6]
The ratio of the volume of the plurality of first holes to the sum of the volume of the first transparent resin and the volume of the plurality of first transparent particles, or the ratio, the volume of the second transparent resin, and the plurality of first volumes The ratio of the volume of the plurality of second holes to the sum of the volume of two transparent particles is in the range of 40% to 80%, and the optical according to [4] or [5] parts.
[7]
[6] The optical component according to [6], wherein the ratio of the thickness of the back diffusion layer to the thickness of the transparent resin layer is in the range of 1/18 to 1/6.
[8]
[7] The optical component according to [7], wherein the ratio of the thickness of the front diffusion layer to the thickness of the back diffusion layer is in the range of 6/19 to 1.
[9]
A plurality of main surfaces facing the multi-layer diffusion layer such that the transparent resin layer is interposed between the main surface and the back surface diffusion layer, and a lens or a prism each constituting the other main surface The optical component according to any one of [1] to [8], further comprising a relief layer provided with a convex portion.
[10]
The optical component according to any one of [1] to [9], wherein a maximum warpage amount when heated to 80 ° C. is less than 2% of a long side.
[11]
The optical component according to any one of [1] to [10];
A light source for illuminating the optical component;
A backlight unit comprising:
[12]
A display device comprising the backlight unit according to [11] and a display panel facing the light source with the optical component interposed therebetween.

1 is a cross-sectional view schematically showing an optical component according to one embodiment of the present invention. Sectional drawing which shows roughly the modification of the optical component shown in FIG. Sectional drawing which shows schematically the other modification of the optical component shown in FIG. Sectional drawing which shows schematically the further another modification of the optical component shown in FIG. Sectional drawing which shows schematically the further another modification of the optical component shown in FIG. The perspective view which expands and shows a part of optical component shown in FIG. The top view which shows an example of a backlight unit roughly. Sectional drawing which shows an example of a display apparatus roughly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Lens array, 6 ... Light transmissive base material, 7 ... Adhesive layer, 8 ... Mask layer, 9 ... Optical sheet, 10 ... Diffusion layer, 11 ... Transparent resin layer, 12 ... Multi-layer diffusion layer, 13 ... Multi-layer diffusion layer , 14 ... lens array, 15 ... prism array, 15a ... prism, 16 ... light source, 17 ... reflective layer, 18 ... display panel.

Claims (4)

A transparent resin layer including a light incident surface on which light emitted from a light source is incident and a light emitting surface that emits light incident on the light incident surface;
A first transparent resin, a plurality of first holes distributed in the first transparent resin, distributed in the first transparent resin, covering the light incident surface, and the first transparent resin has a refractive index A back diffusion layer including a plurality of first transparent particles having different from each other;
The light emitting surface is coated, the second transparent resin, the plurality of second holes distributed in the second transparent resin, and the second transparent resin are distributed in the second transparent resin, and the second transparent resin has a refractive index. A front diffusion layer including a plurality of second transparent particles having different
Comprising a multilayer diffusion layer consisting of
The ratio of the volume of the plurality of first holes to the sum of the volume of the first transparent resin and the volume of the plurality of first transparent particles, and the volume of the second transparent resin and the plurality of second transparent particles Each of the ratio of the volume of the plurality of second pores to the sum of the volume of the second pore is in the range of 40% to 80%;
The ratio of the thickness of the back diffusion layer to the thickness of the transparent resin layer is in the range of 1/12 to 1/6,
The ratio of the thickness of the front diffusion layer to the thickness of the back diffusion layer Ri near the range of 1/3 to 1,
Maximum warp amount when heated to 80 ° C. light engine's service life you wherein less than 2% der Rukoto the long side.   A plurality of main surfaces facing the multi-layer diffusion layer such that the transparent resin layer is interposed between the main surface and the back surface diffusion layer, each of which constitutes a lens or a prism on the other main surface The optical component according to claim 1, further comprising a relief layer provided with a convex portion. The optical component according to claim 1 or 2 ,
A backlight unit comprising a light source for illuminating the optical component. 4. A display device comprising: the backlight unit according to claim 3; and a display panel facing the light source with the optical component interposed therebetween.

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