JPWO2010029886A1 - Direct backlight unit - Google Patents

Abstract

The present invention is intended to provide a direct type backlight device for a display device that efficiently suppresses tube unevenness and has high brightness without using an optical member that has been subjected to special processing. In the direct type backlight device of the present invention, the reflecting material, the plurality of linear light sources, and the optical member group are arranged in this order, and satisfy the following conditions (i) to (v). (I) The plurality of linear light sources are arranged so that the longitudinal directions of the linear light sources are parallel to each other. (Ii) The haze value based on JIS K 7136 (2000) measured by the optical member closest to the linear light source in the optical member group entering light from the surface on the linear light source side is 99.99. 0% or less. (Iii) There is a prism sheet in the optical member group, and the prism sheet is formed with a plurality of convex shapes extending in one direction on the surface opposite to the linear light source side. The longitudinal directions of the plurality of convex shapes are parallel to the longitudinal directions of the plurality of linear light sources. (Iv) The reflective material has a 60 ° glossiness of 5 or less measured based on JIS K 7105 (1981) of the surface on the linear light source side. (V) When the distance between the centers of adjacent linear light sources in the plurality of linear light sources is L, and the distance from the center of the linear light source to the optical member closest to the linear light source is H, the following formula ( Θ satisfying 1) is 45 ° ≦ θ ≦ 70 °. θ = tan−1 ((L / 2) / H) (1)

Description

  The present invention relates to various display devices, and more particularly to a direct backlight device for a liquid crystal display device.

  Liquid crystal display devices are used in various applications such as notebook computers and mobile phone devices, televisions, monitors, car navigation systems, and the like. The liquid crystal display device incorporates a backlight device serving as a light source, and is configured to display light by controlling light beams from the backlight device through a liquid crystal cell. The characteristic required for this backlight device is not only as a light source for emitting light, but also to make the entire screen shine brightly and uniformly.

  The configuration of the backlight device can be roughly divided into two. One is a system called a sidelight type backlight. This is a method mainly used for, for example, a notebook personal computer or the like that is required to be thin and small, but is characterized by using a light guide plate as a basic configuration. In the case of a sidelight-type backlight, a light source is disposed on the side surface of the light guide plate, light is incident on the light guide plate from the side surface, and light is propagated throughout the surface while totally reflecting inside the light guide plate. A part of the light is removed from the total reflection condition by diffusing dots or the like applied to the back surface, and the light is collected from the front surface of the light guide plate, thereby functioning as a backlight, that is, a surface light source. In the case of a sidelight type backlight, in addition to these configurations, a reflection film that functions to reflect and reuse light leaking from the back surface of the light guide plate, and a diffusion sheet that equalizes the light emitted from the front surface of the light guide plate Various types of optical films are used, such as a light collecting sheet represented by a prism sheet that improves the front luminance, and a luminance improving sheet that improves the luminance on the liquid crystal panel.

  Another method is a method called a direct type backlight. This is a method that is preferably used for television applications that require large size and high brightness, but as a basic configuration, a light guide plate is not used, but fluorescent tubes are arranged directly behind the screen, or a plurality of point light source LEDs are arranged. Its structure is a linear arrangement. By arranging a plurality of linear light sources composed of linear or partially linear fluorescent tubes or LEDs in the back of the screen, it is possible to cope with a large screen and to secure sufficient brightness.

  However, brightness unevenness (luminance unevenness) in the screen due to fluorescent tubes and LEDs arranged at the back of the screen, which is also a feature, is caused, and as a result, the unevenness is a dot and a linear image of the fluorescent tubes and LEDs (hereinafter referred to as tube unevenness). )), Which is a cause of image quality degradation.

  For this reason, in the direct type backlight, in order to eliminate the tube unevenness, a light diffusion plate having extremely strong light diffusibility is arranged on the upper side of the fluorescent tube to make the screen uniform (Patent Document 1). The light diffusing plate is a light diffusing plate made of an acrylic resin or a polycarbonate resin in which fine particles are dispersed. This light diffusing plate eliminates tube unevenness and makes the screen uniform, but because it diffuses strongly, the total light transmittance is low and the light utilization efficiency deteriorates. As a result, the required front brightness is insufficient.

  Therefore, a diffusion sheet showing a light collecting effect in the front direction is disposed on the light diffusion plate while diffusing light isotropically. This diffusion sheet is a sheet called a bead sheet in which a diffusion layer containing fine particles such as organic cross-linked particles is formed on a base material sheet. Unlike a light diffusion plate, this diffusion film is an optical film that exhibits a certain degree of directivity in the front direction. It is.

  In addition to these, a reflecting member that reflects light emitted backward from the fluorescent tube or the LED, a condensing sheet represented by a prism sheet for improving the condensing property, and a light emitted from the fluorescent tube or the LED. A brightness enhancement sheet for separating polarized light and improving the brightness on the liquid crystal panel is incorporated, and a direct type backlight device is configured by combining various sheets.

  However, direct-type backlights used for flat-screen TVs that have been attracting attention in recent years, direct-type backlights that reduce the number of fluorescent tubes installed to reduce power consumption from the viewpoint of environmental friendliness, and heavy metals such as mercury In a direct type backlight device equipped with a small amount of point light source LED, tube unevenness is likely to occur remarkably and luminance may be insufficient. For this reason, it is necessary to use a large number of the optical members described above, which makes it difficult to reduce the thickness, increases the cost, and further increases the power consumption used when manufacturing the optical member, which in turn increases the environmental load. There are concerns.

  In order to solve such a problem, a method (Patent Document 2) for improving the functions and performance of various sheets by applying a prism shape having a sawtooth cross section to the light diffusing plate, and a prism shape having a cross section sawtooth shape. There has also been proposed a method (Patent Document 3) in which a reflecting member is molded into a projection so as to be suitable for the applied light diffusion plate.

JP 2004-29091 A JP 2006-164890 A JP 2006-155926 A

  However, the light diffusing plate having extremely strong light diffusibility as in Patent Document 1 has an effect of eliminating the unevenness of the tube and increasing the uniformity of the screen, but the total light transmittance is not high and it is difficult to increase the luminance. .

  In addition, the method of molding the light diffusing plate and the reflecting member as in Patent Documents 2 and 3 is not preferable from the viewpoint of cost and productivity, and it is difficult to achieve both uniformity and luminance, and it is a drastic measure. The actual situation is not reached.

  In view of the background of such a prior art, the present invention provides a direct-type backlight device for a display device that efficiently suppresses tube unevenness and has high luminance. That is, the present invention provides a direct-type backlight device for a display device that efficiently suppresses tube unevenness and has high brightness even when used without applying special processing to an optical member.

In order to solve this problem, the present invention employs the following configuration. That is, in the direct type backlight device of the present invention, the reflecting material, the plurality of linear light sources, and the optical member group are arranged in this order, and satisfy the following conditions (i) to (v).
(I) The plurality of linear light sources are arranged so that the longitudinal directions of the linear light sources are parallel to each other.
(Ii) The optical member closest to the linear light source in the optical member group has a haze value of 99.99 based on JIS K 7136 (2000) measured by making light incident from the surface on the linear light source side. 0% or less.
(Iii) There is a prism sheet in the optical member group, and the prism sheet is formed with a plurality of convex shapes extending in one direction on the surface opposite to the linear light source side. The longitudinal directions of the plurality of convex shapes are parallel to the longitudinal directions of the plurality of linear light sources.
(Iv) The reflective material has a 60 ° glossiness of 5 or less measured based on JIS K 7105 (1981) on the surface of the linear light source.
(V) When the distance between the centers of adjacent linear light sources in the plurality of linear light sources is L, and the distance from the center of the linear light source to the optical member closest to the linear light source is H, the following formula ( Θ satisfying 1) is 45 ° ≦ θ ≦ 70 °.

θ = tan ⁻¹ ((L / 2) / H) (1)

  ADVANTAGE OF THE INVENTION According to this invention, even if it does not use the optical member which gave the special process, the direct-type backlight apparatus for display apparatuses which suppresses tube | pipe nonuniformity efficiently and is high-intensity can be provided.

It is sectional drawing of the direct type | mold backlight apparatus of this invention. It is a figure which shows typically the direct type | mold backlight apparatus used for the pipe unevenness and brightness | luminance evaluation of this invention from upper part.

  The present invention, which is a direct type backlight device capable of suppressing the above-mentioned problem, that is, tube unevenness, has earnestly studied the combination of the optical member configuration and the optical characteristics of the optical member, and the member having the specific optical characteristic is made into the specific combination. As a result, it has been clarified that such a problem can be solved all at once without performing special processing on the optical member.

In the direct type backlight device of the present invention, the reflecting material, the plurality of linear light sources, and the optical member group are arranged in this order, and satisfy the following conditions (i) to (v).
(I) The plurality of linear light sources are arranged so that the longitudinal directions of the linear light sources are parallel to each other.
(Ii) The optical member closest to the linear light source in the optical member group has a haze value of 99.99 based on JIS K 7136 (2000) measured by making light incident from the surface on the linear light source side. 0% or less.
(Iii) There is a prism sheet in the optical member group, and the prism sheet is formed with a plurality of convex shapes extending in one direction on the surface opposite to the linear light source side. The longitudinal directions of the plurality of convex shapes are parallel to the longitudinal directions of the plurality of linear light sources.
(Iv) The reflective material has a 60 ° glossiness of 5 or less measured based on JIS K 7105 (1981) on the surface of the linear light source.
(V) When the distance between the centers of adjacent linear light sources in the plurality of linear light sources is L, and the distance from the center of the linear light source to the optical member closest to the linear light source is H, the following formula ( Θ satisfying 1) is 45 ° ≦ θ ≦ 70 °.

θ = tan ⁻¹ ((L / 2) / H) (1)
With such a direct type backlight configuration, the reason why the tube unevenness can be suppressed is not clear, but it is presumed that the reason is as follows.

  That is, of the light emitted from the fluorescent tube or LED, the light reaching the reflector side is reflected and diffused and reflected at an angle on the reflector until it enters the prism sheet. The reflected light is diffused again by passing through the optical member having the haze value of (ii), so that when it reaches the prism sheet, it is diffused at an angle suitable for the angle changing / condensing function of the prism, It is estimated that it contributes to the suppression of tube unevenness. Hereinafter, each member will be described in detail.

  In the direct type backlight device of the present invention, (i) a plurality of linear light sources are arranged such that the longitudinal directions of the respective linear light sources are parallel to each other. As used herein, the linear light source means that the light source itself is linear, has a linear part in the light source (such as a U-shaped tube or W-shaped tube), has a point light source arranged in a linear shape, or There is no particular limitation as long as light and darkness can be observed in a straight line. For example, a fluorescent tube typified by a cold cathode tube or a point light source LED (white type and RGB type) arranged linearly is preferably used. The direction along these straight lines is the longitudinal direction of the linear light source.

  In the direct type backlight device of the present invention, a plurality of these linear light sources are arranged in parallel. The plurality of linear light sources may not be arranged strictly in parallel, and may be arranged substantially in parallel so that the acute angle formed by the longitudinal direction of each linear light source is 10 ° or less.

  It is also a preferred aspect that the arrangement pitch of the light sources is unequal within the plane of the direct type backlight unit device. For example, when it is desired to brighten the central portion of the direct type backlight device, this can be achieved by shortening the light source array pitch at the central portion of the screen. Moreover, since it becomes dark near the frame of the casing at the edge of the screen, it can be brightened by shortening the arrangement pitch here. As described above, for the purpose of adjusting the brightness in the screen, it is preferable to make the arrangement pitches of the light sources unequal, and this is effective.

  The direct type backlight device according to the present invention is measured according to JIS K 7136 (2000), in which (ii) the optical member closest to the linear light source in the optical member group is irradiated with light from the surface on the linear light source side. It is necessary that the haze value based on is 99.0% or less. If the haze value is larger than 99.0%, it is presumed that excessive diffused light increases. Even in the direct type backlight device that satisfies the conditions (i), (iii), (iv), and (v), the tube unevenness is generated. It cannot be suppressed. If the haze value is 99.0% or less, the lower limit value is not particularly limited because an effect of suppressing tube unevenness in the direct type backlight device is obtained, but the substantial lower limit value is 0.0%. . The smaller the haze value, the smaller the effect of suppressing tube unevenness, but there is a merit that high brightness can be obtained.On the other hand, the larger the haze value, there is a merit that the effect of suppressing tube unevenness can be obtained. Select according to your needs. In the sense of achieving both the effect of suppressing tube unevenness and brightness, there are some combinations with other materials such as reflectors. However, the haze value is 97.5-98.5%, which is directly under a good performance balance. A type backlight device is preferable because it is highly possible.

  The haze value according to the present invention is measured based on JIS K 7136 (2000) using a turbidimeter (cloudiness meter) NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd. First, after standardizing the equipment, cut out such a member to a size of 8cm square and perpendicular to the surface of the linear light source when installed in the direct type backlight device (within ± 2 ° error) Set and measure so that a parallel light beam enters. Five samples at four corners and the center part are measured for five samples per sample, and an average value of a total of 25 points is set as a haze value.

  Although it is not clear why the effect of suppressing tube unevenness can be obtained by disposing an optical member having a haze value of 99.0% or less closest to the linear light source, it is estimated that the reason is as follows. Yes.

  That is, when light transmitted through an optical member arranged closest to the linear light source is incident on a prism sheet, which will be described later, it is presumed that the incident angle has a suitable angle distribution for the prism sheet, and the haze value is 99.99. If it is larger than 0%, the effect of suppressing tube unevenness cannot be obtained, so that the haze value of the optical member capable of providing the incident angle distribution is 99.0% or less. Even if they are arranged in the order of the optical member having a haze value exceeding 99.0% and the optical member having a haze value of 99.0% or less from the linear light source side, the effect of the present invention cannot be obtained. The optical member closest to the linear light source may be of any material and form as long as the haze value is 99.0% or less. For example, acrylic resin, polystyrene resin, polycarbonate resin, main chain and / or side Examples thereof include a resin or the like having a chain having an alicyclic structure and an additive such as particles, which are molded into a plate or film / sheet, and a fiber or cloth sheet. Furthermore, the resin layer containing particles such as a prismatic shape or a hemispherical shape such as a prism shape or a hemispherical shape, or a polarized light separating function for transmitted light, as long as the effect of the invention is not impaired. Although not limited to these, a prism-shaped optical member is preferably used in order to obtain a higher brightness and ability to suppress tube unevenness in a well-balanced manner. Specifically, as these optical members, for example, an acrylic resin light diffusing plate Sumipex (registered trademark) RM series (manufactured by Sumitomo Chemical Co., Ltd., Clarex (registered trademark) DR series (Nitto Resin Co., Ltd.) Panlite (registered trademark) series of polycarbonate resin light diffusion plate (manufactured by Teijin Chemicals Ltd.), polystyrene resin light diffusion plate (manufactured by Idemitsu Unitech Co., Ltd.), alicyclic resin light diffusion plate The ZEONOR diffusion plate series (manufactured by Optes Co., Ltd.) and the like can be mentioned, but are not particularly limited thereto.

  In the direct type backlight device of the present invention, (iii) the prism sheet is formed with a plurality of convex shapes extending in one direction on the surface opposite to the linear light source side, and the longitudinal direction of the plurality of convex shapes is It is necessary that the longitudinal directions of the plurality of convex shapes are parallel to the longitudinal direction of the plurality of linear light sources. If such a convex shape is not formed, tube unevenness cannot be suppressed even in a direct type backlight device that satisfies the conditions (i), (ii), (iv), and (v). Here, the convex shape may be any shape, and the shape observed from a cross section perpendicular to the longitudinal direction of the convex shape is, for example, a semicircular shape (or its inverted shape) like a lenticular lens, or a sine curve. Shape, almost elliptical shape, almost triangular shape (isosceles triangle or non-isosceles triangle) with acute angle, obtuse angle, right angle apex angle, almost polygonal shape (square, rectangle, Trapezoids, polygons other than these), the shape of the apex portion of the substantially triangular shape is rounded, the shape of a wave, the random shape in which the shapes and sizes are irregularly different, and the like. It is not limited to these, You may combine those types in multiple types. These convex shapes may be provided without gaps on the sheet surface, that is, provided so as to be spread without a flat portion, or may be provided with regular or irregular spacing, and are not particularly limited.

  The method of providing these convex shapes is not particularly limited. For example, a method of forming an ultraviolet curable or thermosetting resin on a base sheet and then molding it with a mold or the like, or injection molding a molten resin Various methods such as a method for embossing and a method for embossing may be selected as appropriate. A particularly preferable convex shape is a substantially triangular shape having a right apex angle, and specific examples thereof include the vikuiti BEF series (manufactured by 3M) and the prism film HGL series (manufactured by EFUN TECHNOLOGY CO. Ltd). It is done.

  The material of the base sheet for providing the convex shape is, for example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, cyclohexanedimethanol copolymer polyester resin, isophthalic acid copolymer polyester resin, Polyester resins such as spiroglycol copolymer polyester resin and fluorene copolymer polyester resin, resins having an alicyclic structure in the main chain and / or side chain, polyethylene, polypropylene, polymethylpentene, alicyclic olefin copolymerization Polyolefin resin such as resin, acrylic resin such as polymethyl methacrylate, polycarbonate, polystyrene, polyamide, polyether, polyesteramide, polyetherester, polyvinyl chloride And copolymers and these components, or a thermoplastic resin such as a mixture of these resins. Among these, in terms of mechanical strength, heat resistance, dimensional stability, biaxially stretched polyethylene terephthalate, polyethylene-2,6-naphthalate, or a copolymer with other components based on these, Although polyester resins, such as a mixture, are used more preferably, it is not specifically limited to these.

  Further, even if the convex shape is provided, the above conditions (i), (ii), (iv), and (v) are satisfied when the convex shape is arranged so that the longitudinal direction thereof is not parallel to the longitudinal direction of the linear light source. Even in a direct type backlight device, tube unevenness cannot be suppressed. Here, the longitudinal direction of the convex shape and the longitudinal direction of the linear light source do not need to be completely parallel, and the acute angle formed by the longitudinal direction of the convex shape and the longitudinal direction of the linear light source is 10 ° or less. An effect of suppressing tube unevenness can be expressed.

  The direct-type backlight device of the present invention requires (iv) that the 60 ° glossiness measured on the basis of JIS K 7105 (1981) of the surface of the reflective material on the side of the linear light source is 5 or less. . If the 60 ° glossiness is greater than 5, tube unevenness cannot be suppressed even in a direct type backlight device that satisfies the conditions (i), (ii), (iii), and (v). The 60 ° gloss is preferably 4 or less, more preferably 3 or less.

  The glossiness according to the present invention is as follows based on JIS K 7105 (1981) with the surface of the reflective material facing the linear light source side, using a digital variable angle gloss meter (UGv-4D) manufactured by Suga Test Instruments. Measure according to the procedure. Adjusting the incident angle and the light receiving angle to 60 °, the diaphragm is 0.75 ± 0.25 ° in the incident plane on the light source side, 0.75 ± 0.25 ° in the vertical plane, and the light receiving side is 4.4 ± in the incident plane. Install the slits attached to the equipment so that the angle is 0.1 ° and 11.7 ± 0.2 ° in the vertical plane. Next, the standard configuration is performed using the dark box attached to the equipment and the primary reference plane (black glass). A 10 cm square sample is cut out from each reflecting material, set in a measuring device, and pressed with a sample press lined with black felt so that the sample does not warp. Five samples are measured for each reflector, and the average value is defined as a glossiness of 60 °.

  The reflective material is not particularly limited as long as the 60 ° glossiness is 5 or less, and is not particularly limited. For example, a metal layer or a white layer is provided on a metal or alloy plate or base material. , A non-woven fibrous material molded into a sheet, an incompatible organic or inorganic particle inside the resin and molded into a white film or sheet, a large number of bubbles inside the resin And a white film molded into a sheet or the like. Of these, white films and sheets with many bubbles inside the resin are easy to adjust glossiness, uniform reflection performance for light sources with good color reproducibility such as LEDs, direct type backlight This is preferable from the viewpoint of brightness when incorporated in the apparatus. Examples of the method of incorporating bubbles inside include a method of foaming the inside of the resin, a method of containing incompatible organic or inorganic particles with the resin, and a method of forming bubbles around the particles in a process such as stretching. It is done. In particular, the reflective material according to the present invention should have a high visible light reflectance, and for this purpose, a white film containing bubbles therein is preferably used. Although these white films are not limited, porous unstretched or biaxially stretched polypropylene films and porous unstretched or stretched polyethylene terephthalate films are preferably used as examples. Regarding these production methods and the like, [0034] to [0057] of JP-A-8-262208, [0007] to [0018] of JP-A-2002-90515, and [0008] of JP-A-2002-138150. To [0034] and the like. Among them, a porous white biaxially stretched polyethylene terephthalate film disclosed in Japanese Patent Application Laid-Open No. 2002-90515, and a porous white biaxially mixed and / or copolymerized with polyethylene naphthalate from the viewpoint of heat resistance and reflectance. An axially stretched polyethylene terephthalate film is particularly preferable as the white film as the reflective material according to the present invention for the reasons described above.

  The structure of such a white film may be appropriately selected depending on the application to be used and required characteristics, and is not particularly limited, but is a single layer having at least one layer and / or a composite having two or more layers. A film is preferable, and it is preferable that at least one layer thereof contains at least one of bubbles, inorganic particles, and organic particles.

  An example of a single layer configuration (= 1 layer) is, for example, a white film having only a single A layer, and the A layer contains one or more of bubbles, inorganic particles, and organic particles. Is mentioned. In addition, as an example of a two-layer structure, a white film having a two-layer structure of A layer / B layer in which a B layer is laminated on the A layer, and at least one of these A and B layers includes bubbles, The thing of the structure containing any one or more of an inorganic particle and an organic particle is mentioned. Further, as an example of the three-layer structure, as described above, a white film having a three-layer laminated structure in which three layers of A layer / B layer / A layer and A layer / B layer / C layer are laminated, The thing of the structure which contained any 1 or more types of a bubble, an inorganic particle, and an organic particle in at least 1 layer is mentioned. In the case of a three-layer configuration, the B layer is most preferably a layer containing bubbles from the viewpoint of productivity.

  The number average particle diameter of the inorganic fine particles and / or organic particles contained in the white film is preferably 0.3 to 2.0 μm. As such organic particles, resins mainly composed of a high-melting cross-linked polymer component are preferable. For example, polyester resin, polyamide resin particles such as benzoguanamine, polyurethane resin, acrylic resin, methacrylic resin, polyamide resin, polyethylene resin, polypropylene Examples thereof include resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, fluorine-based resins, silicone resin particles, and hollow particles thereof. These resins may be used alone, or two or more copolymers or a mixture thereof may be used. In terms of the light resistance of the white film, it is preferable that the contained spherical particles contain an ultraviolet absorber and a light stabilizer. Examples of the inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, silica, alumina, mica, titanium mica, talc, clay, Kaolin, lithium fluoride, calcium fluoride, or the like can be used.

  As an example of such a white film, as a white film having a single layer structure, Lumirror (registered trademark) E20 (manufactured by Toray Industries, Inc.), SY64, SY70 (manufactured by SKC), White Lefster (registered trademark) WS-220 (manufactured by Mitsui Chemicals, Inc.) and the like, and examples of the white film having a two-layer structure include Tetron (registered trademark) film UXZ1, UXSP (manufactured by Teijin DuPont Films Co., Ltd.), and the like. As the white film of the configuration, Lumirror (registered trademark) E60L, E6SL, E6SR, E6SQ, E6Z, E6Z2, E80, E80A (made by Toray Industries, Inc.), Tetron (registered trademark) film UX, UXH (Teijin DuPont film) And PL230 (Mitsubishi Resin Co., Ltd.). Moreover, as an example of a white sheet having a configuration other than these, Optilon ACR3000, ACR3020 (manufactured by DuPont), MCPET (registered trademark) (manufactured by Furukawa Electric Co., Ltd.) can be mentioned. If these (iv) surfaces facing the linear light source have a 60 ° glossiness of 5 or less according to JIS K 7105 (1981), they are used as a reflector of the direct type backlight device of the present invention as a single unit. If the glossiness is higher than 5, the glossiness should be adjusted to 5 or less by the method described later.

  When the 60 ° glossiness of the film or sheet base material itself is larger than 5, the reflective material in the present invention is further adjusted to 60 ° glossiness to 5 or less by further various processing on the base material. There is a need. The processing method is not particularly limited. For example, a method of molding with a mold after providing an ultraviolet curing or thermosetting resin, a method of embossing, a method of sandblasting, a method of laminating, or a coating process Various methods such as a method, a method of peeling a surface layer among two or more layers, and the like may be appropriately selected.

  The reflecting material in the present invention preferably has a resin layer containing particles on the surface on the linear light source side. By containing particles, it is easy to adjust the 60 ° glossiness to 5 or less, which leads to suppression of tube unevenness. The shape of the particles is not uniquely limited. For example, a flat shape such as a star shape, a leaf shape, or a disk shape, a rhombus shape, a rectangular shape, a needle shape, a confetti shape, an aspheric shape such as an indefinite shape. In addition, spherical (not necessarily only a true sphere, but a particle whose cross-sectional shape is surrounded by a curved surface such as a circle, an ellipse, a substantially circle, a substantially ellipse, etc.), etc. The particles having these shapes may be porous, nonporous or hollow, and are not particularly limited thereto. Furthermore, if the 60 degree glossiness becomes 5 or less by containing the particles, any of an organic compound, an inorganic substance, and an inorganic compound may be used, and the particle is not uniquely limited.

  The method of providing a resin layer containing particles on the surface of the reflective material on the linear light source side is, for example, gravure coating, roll coating, spin coating, reverse coating, bar coating, screen coating with a coating liquid containing particles and a binder resin. Using various coating methods such as blade coating, air knife coating, and dipping, the coating layer can be applied at the time of production of the reflective material (in-line coating) or on the reflective material after completion of crystal orientation (off-line coating). Examples of the method include a method of forming, and a method of bonding a film or sheet containing particles by lamination or the like, but is not particularly limited thereto. Further, the surface on which the layer containing the particles is provided is not particularly limited, and the reflective material is a two-layer structure of A layer / B layer, A layer / B layer / A layer or A layer / B layer / C layer. If it is a three-layer structure, it may be provided on either side.

  Examples of the reflective material having a layer containing such particles include Lumirror (registered trademark) E6QD, E6ZD (manufactured by Toray Industries, Inc.), DR240T, RE240T (manufactured by ETRNAL CHEMICAL CO., Ltd).

  When the reflective material in the present invention is used in a direct type backlight device, particles contained in the reflective material or the resin layer may be deteriorated by light emitted from a light source, particularly a lamp such as a cold cathode tube, particularly ultraviolet rays (for example, Optical degradation such as yellowing, or degradation degradation that lowers the molecular weight). Therefore, it is preferable to contain an ultraviolet absorber and / or a light stabilizer within the range that does not impair the effects of the present invention in the resin that forms the resin layer containing particles provided on the reflector.

  In the present invention, the content of the particles in the resin layer provided on the reflective material is not particularly limited as long as the 60 ° gloss is 5 or less, and also depends on the type of the reflective material, the particles, and productivity. Although it cannot be limited uniquely, it is sufficient to select a content ratio that has a good balance between the effect of suppressing tube unevenness and luminance. Considering glossiness and productivity, it is preferably 0.2% by weight or more and 75% by weight or less with respect to the entire resin layer. When the content of the particles is less than 0.2% by weight, the 60 ° gloss may not be 5 or less. Moreover, since productivity will be extremely inferior when it exceeds 75 weight%, it is preferable to control to 75 weight% or less. Preferably they are 50 to 75 weight%, More preferably, they are 65 to 75 weight%.

  Although the thickness of the resin layer containing the particles provided in the reflective material in the present invention depends on the type of the reflective material, the particles, and the content, it is preferably 0.05 to 50 μm. If the thickness of the resin layer is less than 0.05 μm, the effect of suppressing tube unevenness may be impaired. On the other hand, if the thickness exceeds 50 μm, it is not preferable from the viewpoint of economy. In addition, the thickness of the resin layer here is the total thickness of the resin layer containing particles. When it has one or more layers, it is obtained from the thickness of the entire resin layer, that is, the thickness of the entire resin layer of a plurality of layers. It is a thing.

  In the direct type backlight device according to the present invention, (v) the linear light source has a distance L between the centers of adjacent linear light sources, and a distance from the center of the linear light source to the optical member closest to the linear light source. When H is set, it is necessary that θ satisfying the following formula (1) is 45 ° ≦ θ ≦ 70 °.

θ = tan ⁻¹ ((L / 2) / H) (1)
More preferably, it is arranged such that θ satisfying the formula (1) is 50 ° ≦ θ ≦ 70 °, and particularly preferably, θ satisfying the formula (1) is 60 ° ≦ θ ≦ 70 °. It is arranged so that.

  Here, θ increases means that the distance between the linear light source and the optical member closest to the linear light source decreases, or the distance between the linear light sources increases. Thin direct-type backlight devices tend to be the former, and direct-type backlight devices with a reduced number of fluorescent tubes mounted for the purpose of reducing power consumption from the viewpoint of environmental friendliness tend to be the latter. Surprisingly, in the present invention, when θ satisfying the formula (1) is large, the effect of suppressing tube unevenness is larger, that is, it is larger in a direct type backlight device that is thin or has a reduced number of fluorescent tubes. It means that the tube unevenness suppression effect is exhibited.

  More preferably, it is a direct type backlight in which the linear light source is arranged so that θ satisfying the formula (1) satisfies 45 ° ≦ θ ≦ 70 ° and H ≦ 10 mm, and further has a great effect of suppressing tube unevenness. .

  In the direct backlight device of the present invention, the reflector, the plurality of linear light sources, and the optical member group are arranged in this order, and as long as the conditions (i) to (v) are satisfied, Furthermore, an optical member having a haze value of 99.0% or less, a prism sheet, or an optical member of a film or sheet other than these (hereinafter referred to as other optical sheet) may be included. As a configuration of the optical member group, “optical member / prism sheet / other optical sheet having haze value of 99.0% or less” “optical member / other optical sheet having haze value of 99.0% or less” in order from the linear light source side / Prism sheet "" optical sheet having a haze value of 99.0% or less / prism sheet / prism sheet ", but not limited thereto.

  As these other optical sheets, for example, a film or sheet having a function capable of improving light diffusibility and luminance by providing a layer containing particles or a hemispherical projection on a base material, or controlling polarization characteristics of transmitted light Examples thereof include a film or sheet having a polarization separation function, but are not particularly limited thereto. Specific examples of such films and sheet members include, for example, Light-Up 100GM2, Light-Up 100GM3 (manufactured by Kimoto Co., Ltd.), UTEI, UTEII (manufactured by MNTech Co., Ltd.), vikuiti DBEF series (manufactured by 3M) However, it is not particularly limited to these.

  In the resin layer containing an optical member having a haze value of 99.0% or less, a prism sheet, a reflective material, and particles laminated on the reflective material in the present invention, various additives within a range that does not impair the effects of the present invention. Can be added. Examples of additives include organic and / or inorganic fine particles, luminescent materials represented by fluorescent brightening agents, crosslinking agents, flame retardants, flame retardant aids, heat stabilizers, oxidation stabilizers, organic lubricants, Antistatic agents, nucleating agents, dyes, fillers, dispersants, coupling agents, and the like can be used.

  The measurement method and evaluation method are shown below.

(1) Haze value of member It measures based on JISK7136 (2000) using Nippon Denshoku Industries Co., Ltd. product, and a turbidimeter (cloudiness meter) NDH-2000. For the sample, a member (excluding the reflecting material) arranged closest to the linear light source of the direct type backlight device is cut into an 8 cm square. When multiple members are pasted together with an adhesive, etc., immerse in an organic solvent for a sufficient time, peel off each member so as not to damage the surface, wipe off the adhesive, etc., and then dry sufficiently Use things. When a sample of a member arranged closest to the extracted linear light source is installed in a direct type backlight device, a parallel light beam is incident at a right angle (within an error of ± 2 °) from the surface on the linear light source side. Set and measure. Five samples at four corners and the center part are measured for five samples per sample, and an average value of a total of 25 points is set as a haze value.

(2) Presence / absence of convex shape of the sheet, and the shape of the convex shape. Using a rotary microtome manufactured by Nippon Microtome Laboratories Co., Ltd., in a direction perpendicular to the sheet plane at a knife inclination angle of 3 °, and Cut as perpendicular to the longitudinal direction of the convex shape as possible. Using the scanning electron microscope ABT-32 manufactured by Topcon Corporation, the obtained sheet cross-section is convex with an observation magnification of 2500 times so that the convex shape is projected in the visual field region, and the image contrast is adjusted appropriately. Observe the shape of the mold shape. Similarly, a total of five places are observed at intervals of 2 to 5 cm in the longitudinal direction of the convex shape, and it is observed whether or not the plurality of convex shapes extend in substantially one direction. When the convex shape cannot be confirmed, the observation is similarly performed at an observation magnification of 5000 times. When the convex shape is not observed, the observation is performed at an observation magnification of 10,000. When it can be confirmed that a plurality of convex shapes extend substantially in one direction at any observation magnification, it is assumed that there is a convex shape, and the mold shape extends in substantially one direction at any observation magnification. If it cannot be confirmed, no convex shape is assumed.

(3) 60 ° glossiness of the reflective material The surface of the reflective material facing the linear light source side is based on JIS K 7105 (1981) using a digital variable angle gloss meter (UGv-4D) manufactured by Suga Test Instruments. Measure according to the following procedure. Adjusting the incident angle and the light receiving angle to 60 °, the diaphragm is 0.75 ± 0.25 ° in the incident plane on the light source side, 0.75 ± 0.25 ° in the vertical plane, and the light receiving side is 4.4 ± in the incident plane. Install the slits attached to the equipment so that the angle is 0.1 ° and 11.7 ± 0.2 ° in the vertical plane. Next, standard calibration is performed using a dark box and a primary reference plane (black glass). A 10 cm square sample is cut out from each reflector, set in a measuring device, and pressed by a sample press lined with black felt so that the sample does not warp. Five samples are measured for each reflector, and the average value is taken as 60 ° gloss.

(4) Presence / absence of resin layer containing particles of reflecting material, shape of the sample Using a rotary microtome manufactured by Nippon Microtome Laboratories Co., Ltd., cutting the direction perpendicular to the reflecting material plane at a knife inclination angle of 3 ° To do. Using the scanning electron microscope ABT-32 manufactured by Topcon Corporation, the obtained reflecting material cross section was adjusted at an observation magnification of 2500 times and the image contrast was appropriately adjusted so that the resin layer was projected in the visual field region. The presence or absence of the resin layer, the presence or absence of particles, and the shape of the particles on the linear light source side are observed. If the presence / absence of the resin layer, the presence / absence of particles, and the shape of the particles cannot be discriminated, the observation is similarly performed at an observation magnification of 5000 times. If the resin layer or / and particles are confirmed at any magnification, the resin layer or / and particles are present. If the resin layer or / and particles are not confirmed at any magnification, the resin No layers or / and particles.

(5) Luminance and tube unevenness of direct type backlight device After various members are arranged in direct type backlights (two types in total) described later, the fluorescent tube is turned on. 1 hour after lighting, using a two-dimensional luminance meter CA-2000 manufactured by Konica Minolta Sensing Co., Ltd., as shown in FIG. 1, in the front direction, that is, directly below the backlight device. The brightness and tube unevenness are measured from the vertical direction. The measurement area is the central part of the direct type backlight device, 20 cm long in the direction parallel to the fluorescent tube, and 7 times the distance between the centers of the adjacent fluorescent tubes in the direction perpendicular to the fluorescent tube. It is set as an area where seven fluorescent tubes enter vertically in all directions. The brightness and uniformity of this measurement area are obtained.

  The luminance was evaluated as the average luminance of the area.

The tube unevenness is obtained as follows. As shown in FIG. 2, nine lines (dotted line 10 in FIG. 2) that divide the vertical direction of the region into 10 equal parts at intervals of 2 cm are drawn. Each of these lines is a measurement line for tube unevenness. When the luminance is measured along each measurement line of tube unevenness, a plurality of peaks with higher brightness and a plurality of valleys with lower brightness than the surroundings are observed. For one measurement line for tube unevenness, the average value of 5 points from the highest luminance order is Lmax, the average value of the five points from the lowest luminance order is Lmin, the average value of Lmax and Lmin is Lave, and the following formula ( 2) is used to calculate the uniformity of the measurement line of this tube unevenness. And the average value of the uniformity of 9 measurement lines of tube unevenness was made into tube unevenness. The larger the average value, the stronger the tube unevenness, and the smaller the average value, the weaker the tube unevenness.
-Uniformity (%) for one measurement line of tube unevenness (%) = (Lmax−Lmin) / Lave × 100 (2).

  The configuration of the apparatus used in the examples and comparative examples is shown below.

(1) Device 1
Size: 32 inches (725mm x 413mm, diagonal 834mm)
Diameter of fluorescent tube: 3mm
Number of fluorescent tubes: 19 Distance between centers of fluorescent tubes L: 20.4 mm
Distance H: 6.5 mm between the center of the fluorescent tube and the closest optical member
Distance between the center of the fluorescent tube and the reflector: 3.0 mm
θ: 57.5 ° (θ = tan ⁻¹ ((L / 2) / H)).

(2) Device 2
Size: 20 inches (424mm x 331mm, diagonal 537mm)
Diameter of fluorescent tube: 4mm
Number of fluorescent tubes: 10 Distance between centers of fluorescent tubes L: 30 mm
Distance H: 13 mm between the center of the fluorescent tube and the nearest optical member
Distance between the center of the fluorescent tube and the reflective material: 6.0 mm
θ: 49.1 ° (θ = tan ⁻¹ ((L / 2) / H)).

(3) Device 3
Size: 32 inches (725mm x 413mm, diagonal 834mm)
Diameter of fluorescent tube: 3mm
Number of fluorescent tubes: 10 Distance between centers of fluorescent tubes L: 40.8 mm
Distance H: 9 mm between the center of the fluorescent tube and the closest optical member
Distance between the center of the fluorescent tube and the reflector: 3.0 mm
θ: 66.2 ° (θ = tan ⁻¹ ((L / 2) / H)).

(4) Device 4
Size: 20 inches (424mm x 331mm, diagonal 537mm)
Diameter of fluorescent tube: 4mm
Number of fluorescent tubes: 10 Distance between centers of fluorescent tubes L: 30 mm
Distance H: 16 mm between the center of the fluorescent tube and the nearest optical member
Distance between the center of the fluorescent tube and the reflective material: 6.0 mm
θ: 41.4 ° (θ = tan ⁻¹ ((L / 2) / H)).

(5) Device 5
Size: 32 inches (725mm x 413mm, diagonal 834mm)
Diameter of fluorescent tube: 3mm
Number of fluorescent tubes: 10 Distance between centers of fluorescent tubes L: 40.8 mm
Distance H: 6.5 mm between the center of the fluorescent tube and the closest optical member
Distance between the center of the fluorescent tube and the reflector: 3.0 mm
θ: 72.3 ° (θ = tan ⁻¹ ((L / 2) / H)).

The members A to D used in each example and comparative example, and the stacking order of these members are shown below.
A: Optical member closest to the fluorescent tube (*) If there is a surface with a convex shape, install it with the opposite surface facing the fluorescent tube side.
B: Prism sheet (installation positional relationship between the longitudinal direction of the convex shape on the sheet and the linear direction of the fluorescent tube)
(*) Installed with the opposite side of the surface with the convex shape facing the fluorescent tube.
C: Other optical sheets other than A and B (*) If there is a concavo-convex surface, install it with the opposite surface facing the fluorescent tube.
D: Reflector (*) The glossiness described in Table 1-1 is the value of the surface facing the fluorescent tube.
Lamination order: Listed except for D (reflecting material). A / B / C is laminated in the order of A, B, C from the fluorescent tube side.

Example 1
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III CA DR-80C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B.

(Example 2)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Sumipex E (registered trademark) RM804S (manufactured by Sumitomo Chemical Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B.

(Example 3)
First, a 32-inch LCD TV (manufactured by Hitachi, Ltd., Woo (registered trademark) UT32-Hv700B) is disassembled and has a plurality of convex shapes extending in one direction on the surface opposite to the fluorescent tube side. A resin plate having a thickness of 2 mm was obtained in which the longitudinal direction of the convex shape was installed in parallel with the linear direction of the fluorescent tube. The haze based on JIS K7136 (2000) when light is incident from the fluorescent tube side when the resin plate is mounted before disassembly is 98.3%, and the incident surface is rotated as it is by 90 ° from that state. As a result of the same measurement, the haze was 98.1%. The average value was taken and the haze of the resin plate was 98.2%.
Next, the resin plate was cut to a size that can be installed in the devices 1 to 5 (hereinafter abbreviated as a concavo-convex pattern resin plate), and then evaluated by the devices 1, 2 and 3 in the following configurations AD.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B.

Example 4
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III CA DR-90C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B.

(Example 5)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Reflector prepared by the following production method A (Production method A)
Hals Hybrid (registered trademark) Uv-G720T (acrylic copolymer, 40% concentration solution, refractive index 1.56, manufactured by Nippon Shokubai Co., Ltd.): 10.0 g, ethyl acetate: 7.0 g, techpolymer ( Trademark registration) TRX05S (acrylic spherical particles, refractive index 1.49, manufactured by Sekisui Plastics Co., Ltd.): A coating solution was prepared by adding 9.2 g with stirring. This coating solution was applied to one side of a white film made of 188 μm porous biaxially stretched polyethylene terephthalate (Lumirror (registered trademark) E6SQ manufactured by Toray Industries, Inc.) using Metabar # 16. A coating layer was provided under dry conditions. The glossiness of the reflective material was 5.
Lamination order: A / B.

(Example 6)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B / C.

(Example 7)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: Vikuiti DBEF (manufactured by 3M, sheet having polarization separation function, haze value: 81.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B / C.

(Example 8)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: UTEII (manufactured by MNTtech Co., Ltd., light diffusion sheet with hemispherical protrusions on the surface, haze value: 89.6%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / B / C.

Example 9
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C1: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
C2: Vikuiti DBEF (manufactured by 3M, sheet having polarization separation function, haze value: 81.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / C1 / B / C2.

(Example 10)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / C / B / C / C.

(Example 11)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
D: Reflector prepared by the following production method B (Production method B)
Hals Hybrid (registered trademark) Uv-G720T (acrylic copolymer, 40% concentration solution, refractive index 1.56, manufactured by Nippon Shokubai Co., Ltd.): 10.0 g, ethyl acetate: 7.0 g, techpolymer ( Trademark registration) TRX05S (acrylic spherical particles, refractive index 1.49, manufactured by Sekisui Plastics Co., Ltd.): A coating solution was prepared by adding 9.2 g with stirring. This coating solution was applied to one side of a white film made of 188 μm porous biaxially stretched polyethylene terephthalate (Lumirror (registered trademark) E80A manufactured by Toray Industries, Inc.) using Metabar # 24. A coating layer was provided under dry conditions. The glossiness of the reflective material was 3.

(Comparative Example 1)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III CA DR-90C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Lumirror (registered trademark) E6Sv (manufactured by Toray Industries, Inc., thickness 225 μm)
(Comparative Example 2)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III CA DR-90C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: None D: Reflector prepared by the following production method C (Production method C)
Hals Hybrid (registered trademark) Uv-G720T (acrylic copolymer, 40% concentration solution, refractive index 1.56, manufactured by Nippon Shokubai Co., Ltd.): 10.0 g, ethyl acetate: 24.1 g, techpolymer ( Trademark registration) TRX05S (acrylic spherical particles, refractive index 1.49, manufactured by Sekisui Plastics Co., Ltd.): A coating solution was prepared by adding 4.0 g with stirring. This coating solution was applied to one side of a white film made of 188 μm porous biaxially stretched polyethylene terephthalate (Lumirror (registered trademark) E6SR manufactured by Toray Industries, Inc.) using Metabar # 16. A coating layer was provided under dry conditions. The glossiness of the reflective material was 7.

  (Comparative Example 3).

Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: None C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm).

(Comparative Example 4)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Concavity and convexity pattern resin plate (the longitudinal direction of the convex shape is set parallel to the linear direction of the fluorescent tube)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in the orthogonal direction)
C: None D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm).

(Comparative Example 5)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III C-A DR-70C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C: UTEII (manufactured by MNTtech Co., Ltd., light diffusion sheet with hemispherical protrusions on the surface, haze value: 89.6%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / C / B.

(Comparative Example 6)
Evaluation was made with the above-described apparatuses 1, 2 and 3 in the configurations of A to D below.
A: Clarex (registered trademark) DR-III C-A DR-70C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C1: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
C2: Vikuiti DBEF (manufactured by 3M, sheet having polarization separation function, haze value: 81.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Stacking order: A / C1 / B / C2
(Comparative Example 7)
Evaluation was performed with the devices 4 and 5 in the following configurations A to D.
A: Clarex (registered trademark) DR-III C-A DR-70C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C1: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
C2: Vikuiti DBEF (manufactured by 3M, sheet having polarization separation function, haze value: 81.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Stacking order: A / C1 / B / C2
(Comparative Example 8)
Evaluation was performed with the devices 4 and 5 in the following configurations A to D.
A: Clarex (registered trademark) DR-III C-A DR-70C (manufactured by Nitto Jushi Kogyo Co., Ltd.)
B: Vikuiti BEFIII 90 / 50T (manufactured by 3M, convex shape: triangular shape with apex angle of right angle, convex pitch: 50 μm) (installed in parallel direction)
C1: Light-up 100GM2 (manufactured by Kimoto Co., Ltd., light diffusion sheet provided with a layer containing particles on the surface layer, haze value: 95.5%)
C2: Vikuiti DBEF (manufactured by 3M, sheet having polarization separation function, haze value: 81.5%)
D: Lumirror (registered trademark) E6QD (manufactured by Toray Industries, Inc., thickness 188 μm)
Lamination order: A / C1 / B / C2.

  Tables 1-1 to 2-2 below show the characteristics of the above-described examples and comparative examples.

  In any of Examples 1 to 11, the effect of suppressing tube unevenness was observed. Among them, when combining the haze value of the optical member closest to the fluorescent tube and the glossiness values on the fluorescent tube side of the reflector in a suitable range, the tube unevenness is suppressed without stacking other optical members, and A configuration of a direct-type backlight device having high luminance was obtained (Example 3).

  In addition, by controlling the haze value of the optical member closest to the fluorescent tube, the balance between the effect of suppressing tube unevenness and the brightness can be changed, and a configuration according to various requirements and applications could be proposed ( Examples 1, 2, 4). Furthermore, by using a reflective material having a lower glossiness, it was possible to further suppress tube unevenness (a comparison between Example 5 and Example 2 and a comparison between Example 6 and Example 11). Further, by stacking other optical members, tube unevenness can be further suppressed, and the stacking order can be arbitrarily selected, so that a variety of options for the direct type backlight device configuration can be obtained (Example 5). To 11). Furthermore, surprisingly, in most configurations, the devices 1 and 3 that are thinner than the direct-type backlight device in which the tube unevenness is more likely to appear and the number of fluorescent tubes to be mounted are reduced compared to the device 2. As a result, the tube unevenness was strongly suppressed, suggesting that it was applied not only to the direct backlight device but also to the module equipment using it. The tube unevenness was particularly good in the device 3 having a large θ angle.

  On the other hand, when the glossiness of the reflective material is larger than 5, the effect of suppressing the tube unevenness of the direct type backlight device is insufficient even when other member configurations are suitable (Example 4 and Comparative Example). 1 and comparison between Example 1 and Comparative Example 2). Even if each member has a suitable value or member shape, if the longitudinal direction of the convex shape of the prism sheet is not parallel to the longitudinal direction of the fluorescent tube, the tube unevenness is worsened. (Comparison between Example 3 and Comparative Example 4). When the haze value of the optical member closest to the fluorescent tube is larger than a specific range, the tube unevenness was not sufficiently suppressed even when a plurality of other optical sheets were laminated (contrast between Example 9 and Comparative Example 6). ). Further, when the haze value of the optical member closest to the fluorescent tube is larger than a specific range, there is another optical sheet having a haze of 99.0% or less between the optical member closest to the fluorescent tube and the prism sheet. However, the suppression of tube unevenness was insufficient (Comparative Examples 5 and 6). In particular, when the prism sheet was not arranged, the tube unevenness appeared remarkably (contrast between Example 3 and Comparative Example 3).

  Further, when the distance between the centers of adjacent linear light sources is L, and the distance from the center of the linear light source to the optical member closest to the linear light source is H, for θ satisfying the following formula (1): When θ is less than 45 ° or θ is greater than 70 °, even if other member configurations are suitable, the tube unevenness appears remarkably (contrast between Example 3 and Comparative Example 7). .

θ = tan ⁻¹ ((L / 2) / H) (1)
Furthermore, when θ is less than 45 ° or θ is greater than 70 °, the tube unevenness was not sufficiently suppressed even when other optical sheets were provided (comparison between Example 5 and Comparative Example 8).

  The direct type backlight device of the present invention can be suitably used not only as a liquid crystal display or liquid crystal Tv but also as various surface light sources and lighting devices.

1: Fluorescent tube (linear light source)
2: Optical member arranged closest to the fluorescent tube (linear light source) 3: Prism sheet 4: Convex-shaped cross-sectional view arranged parallel to the longitudinal direction of the fluorescent tube (linear light source) Example 5: Reflective material 6: other optical sheet laminated below the prism sheet 7: other optical sheet laminated on the prism sheet 8: luminance meter 9: measurement of tube unevenness and luminance 10: measurement line of tube unevenness

Claims (3)

A direct type backlight device in which a reflector, a plurality of linear light sources, and an optical member group are arranged in this order and satisfy the following conditions (i) to (v).
(I) The plurality of linear light sources are arranged so that the longitudinal directions of the linear light sources are parallel to each other.
(Ii) The optical member closest to the linear light source in the optical member group has a haze value of 99.99 based on JIS K 7136 (2000) measured by making light incident from the surface on the linear light source side. 0% or less.
(Iii) There is a prism sheet in the optical member group, and the prism sheet is formed with a plurality of convex shapes extending in one direction on the surface opposite to the linear light source side. The longitudinal directions of the plurality of convex shapes are parallel to the longitudinal directions of the plurality of linear light sources.
(Iv) The reflective material has a 60 ° glossiness of 5 or less measured based on JIS K 7105 (1981) of the surface on the linear light source side.
(V) When the distance between the centers of adjacent linear light sources in the plurality of linear light sources is L, and the distance from the center of the linear light source to the optical member closest to the linear light source is H, the following formula ( Θ satisfying 1) is 45 ° ≦ θ ≦ 70 °.
θ = tan ⁻¹ ((L / 2) / H) (1) The direct-type backlight device according to claim 1, wherein the reflective material has a resin layer containing particles on a surface on the linear light source side. The direct-type backlight device according to claim 1, wherein the distance H is H ≦ 10 mm.

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