JP2014235397A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device that reduces the view angle with a louver film with less loss of light due to the louver film.SOLUTION: A liquid crystal display device of the present invention includes a louver film, liquid crystal panel, and prism sheet in this order from the visual recognition side, and the prism sheet has a convex part on the opposite side to the visual recognition side. In one embodiment, the louver film is closely adhered to the liquid crystal panel. In one embodiment, the effect axis direction of the louver film is substantially parallel to a direction in which the half-value angle of emission light from the prism sheet becomes minimum.

Description

  The present invention relates to a liquid crystal display device.

  In general, a liquid crystal display device is required to have a wide viewing angle when used in a scene where the viewer's position is not fixed and the viewer is visually recognized from any angle (for example, an electronic advertisement, a commonly used television, a personal computer, etc.). In order to realize a wide viewing angle, various techniques using a diffusion sheet, a prism sheet, a wide viewing angle liquid crystal panel, a wide viewing angle polarizing plate, and the like have been studied. On the other hand, when the position of the viewer is limited to a narrow range, a liquid crystal display device capable of displaying an image with a narrow viewing angle (for example, a mobile phone or a public place) for the purpose of preventing peeping or the like. There is also a need for liquid crystal display devices (used in notebook computers, automatic teller machines, vehicle seat monitors, etc.).

  As a method of narrowing the viewing angle, a technique of arranging a louver film on the viewing side surface of a liquid crystal display device is known (for example, Patent Document 1). However, since the louver film limits the viewing angle by blocking a part of the incident light, particularly light having a large incident angle, the liquid crystal display device including the louver film efficiently uses the light from the backlight. It cannot be used. In order to increase the luminance in such a liquid crystal display device, it is necessary to increase the amount of light from the backlight, resulting in a problem that power consumption increases.

Special table 2009-528567 published

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide a liquid crystal display device in which light loss due to the louver film is reduced while the viewing angle is narrowed by the louver film. There is.

The liquid crystal display device of the present invention includes a louver film, a liquid crystal panel, and a prism sheet in this order from the viewing side, and the prism sheet has a convex portion on the side opposite to the viewing side.
In one embodiment, the louver film is in close contact with the liquid crystal panel.
In one embodiment, the effective axis direction of the louver film is substantially parallel to the direction in which the half-value angle of the emitted light from the prism sheet is the smallest.
In one embodiment, the prism sheet is configured by arranging a plurality of triangular prism unit prisms in parallel.
In one embodiment, the liquid crystal display device of the present invention further includes a backlight unit including a light source, a light guide plate, and a specular reflection plate.
In one embodiment, the light guide plate is a light guide plate having prism shapes formed on the back side and the viewing side.
In one embodiment, the prism sheet is configured by arranging a plurality of triangular prism-shaped unit prisms in parallel, and the light source of the backlight unit is disposed on a side substantially parallel to the ridge line direction of the unit prism. .
In one embodiment, the light source of the backlight unit is disposed on a side substantially orthogonal to the effect axis direction of the louver film.

  According to the present invention, a liquid crystal display device with a narrow viewing angle and high brightness can be obtained by providing the prism sheet and the louver film that are convex on the side opposite to the viewing side. Since the liquid crystal display device of the present invention can display an image with high luminance even though it has a louver film, image display with a desired narrow viewing angle and desired luminance can be realized with low power consumption. .

1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a schematic perspective view which shows the prism sheet used for preferable embodiment of this invention. It is a partial schematic perspective view of the louver film used for preferable embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

A. 1 is a schematic sectional view of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device 100 includes a prism sheet 10, a liquid crystal panel 20, and a louver film 30 disposed on the viewer side of the prism sheet 10. Preferably, as in the illustrated example, the louver film 30, the liquid crystal panel 20, and the prism sheet 10 are arranged in this order from the viewing side. The prism sheet 10 has a convex portion on the opposite side (back side) to the viewing side. The liquid crystal panel 20 typically includes a liquid crystal cell 22, a viewing side polarizing plate 21 disposed on the viewing side of the liquid crystal cell, and a back side polarizing plate 23 disposed on the back side of the liquid crystal cell. . Practically, the liquid crystal display device 100 may further include any appropriate other member. For example, the backlight unit 40 is provided on the back side of the prism sheet 10. The backlight unit 40 may be an edge light type or a direct type.

B. Prism Sheet FIG. 2 is a schematic perspective view showing a prism sheet used in a preferred embodiment of the present invention. The prism sheet 10 typically includes a base material portion 11 and a prism portion 12. In addition, you may abbreviate | omit the base material part 11 according to an adjacent member. For example, when the liquid crystal display device includes a reflective polarizer described later, the reflective polarizer can function as a base material portion that supports the prism portion, and thus the base material portion is not necessarily provided. The prism sheet has a function of collecting diffused light from the backlight unit.

  The prism sheet 10 can be bonded to an adjacent member via any appropriate adhesive layer (for example, an adhesive layer, an adhesive layer: not shown).

B-1. Prism Unit In one embodiment, the prism sheet 10 (substantially, the prism unit 12), as shown in FIG. 1, is a plurality of unit prisms 13 that are convex on the side opposite to the viewing side (back side). Are configured in parallel. By disposing the convex portion of the prism sheet 10 toward the back side, the light transmitted through the prism sheet 10 is easily collected. As a result, the amount of light transmitted through the louver film 30 increases, and a liquid crystal display device with high luminance and high utilization efficiency of light from the backlight unit can be obtained.

  Preferably, the unit prism 13 is columnar. The prism sheet composed of columnar unit prisms collects transmitted light in the unit prism arrangement direction X, that is, in a direction substantially orthogonal to the longitudinal direction (ridge line direction) of the unit prisms. As the cross-sectional shape of the unit prism 13, any appropriate shape can be adopted as long as the effect of the present invention can be obtained. The unit prism 13 may have a triangular shape (that is, the unit prism has a triangular prism shape) in a cross section parallel to the arrangement direction and parallel to the thickness direction, or other shape (for example, one of the triangles). Alternatively, both of the slopes may have a plurality of flat surfaces having different inclination angles. The triangular shape may be a shape that is asymmetric with respect to a straight line that passes through the vertex of the unit prism and is orthogonal to the sheet surface (for example, an unequal triangular shape), or a shape that is symmetric with respect to the straight line (for example, two An equilateral triangle). Furthermore, the apex of the unit prism may be a chamfered curved surface, or may be cut to have a flat tip at a tip, and may have a trapezoidal cross section. The detailed shape of the unit prism can be appropriately set according to the purpose. For example, as the unit prism, the configuration described in JP-A-11-84111 can be adopted. In this specification, the expressions “substantially orthogonal” and “substantially orthogonal” include the case where the angle between the two directions is 90 ° ± 10 °, preferably 90 ° ± 7 °, The angle is preferably 90 ° ± 5 °. The expressions “substantially parallel” and “substantially parallel” include the case where the angle between two directions is 0 ° ± 10 °, preferably 0 ° ± 7 °, more preferably 0 ° ± 5 °. Further, in the present specification, the term “orthogonal” or “parallel” may include a substantially orthogonal state or a substantially parallel state.

  Preferably, the longitudinal direction (ridge line direction) of the unit prism 13 is oriented in a direction substantially orthogonal to the transmission axis of the back-side polarizing plate 23. The prism sheet 10 may be arranged (so-called oblique arrangement) such that the ridge line direction of the unit prism 13 and the transmission axis of the back-side polarizing plate 23 form a predetermined angle. The range of the oblique arrangement is preferably 20 ° or less, and more preferably 5 ° or less.

B-2. When providing the base material part 11 in the prism sheet 10, the base material part 11 and the prism part 12 may be integrally formed by extruding a single material. The prism portion may be formed on the film for use. The thickness of the base material portion is preferably 25 μm to 150 μm.

  Any appropriate material can be adopted as the material constituting the base member 11 depending on the purpose and the configuration of the prism sheet. When the prism portion is formed on the base film, specific examples of the base film include (meth) acrylic resins such as cellulose triacetate (TAC) and polymethyl methacrylate (PMMA). And a film formed of polycarbonate (PC) resin. The film is preferably an unstretched film.

  When the base material portion 11 and the prism portion 12 are integrally formed with a single material, the same material as the material for forming the prism portion when the prism portion is formed on the base material portion film is used as the material. Can do. Examples of the prism portion forming material include epoxy acrylate-based and urethane acrylate-based reactive resins (for example, ionizing radiation curable resins). In the case of forming an integrally structured prism sheet, a polyester resin such as PC or PET, an acrylic resin such as PMMA or MS, or a light-transmitting thermoplastic resin such as cyclic polyolefin can be used.

  The base material part 11 preferably has substantially optical isotropy. In this specification, “substantially optically isotropic” means that the retardation value is small enough not to substantially affect the optical characteristics of the liquid crystal display device. For example, the in-plane retardation Re of the base material portion is preferably 20 nm or less, and more preferably 10 nm or less. The in-plane retardation Re is an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. The in-plane phase difference Re is represented by Re = (nx−ny) × d. Here, nx is the refractive index in the direction in which the refractive index is maximum in the plane of the optical member (that is, the slow axis direction), and ny is the direction perpendicular to the slow axis in the plane (that is, the fast phase). (Axial direction), and d is the thickness (nm) of the optical member.

Furthermore, the photoelastic coefficient of the base portion 11 is preferably ^{-10 × 10 -12 m 2 / N~10} × 10 -12 m 2 / N, more preferably -5 × ¹⁰ -12 ^m 2 / N a ^{~5 × 10 -12 m 2 / N} , more preferably from ^{-3 × 10 -12 m 2 / N~3} × 10 -12 m 2 / N.

C. Louver Film FIG. 3 is a partial schematic perspective view of a louver film used in a preferred embodiment of the present invention. The louver film 30 has a louver layer 31. The louver layer 31 includes louver portions 3 and light transmission portions 4 that are alternately formed in a stripe shape. The louver portion blocks or suppresses light transmission, and light having a large incident angle cannot pass through the louver layer. By providing the louver film, the liquid crystal display device of the present invention narrows the viewing angle in the arrangement direction A (lateral direction on the paper surface) of the louver portions. Hereinafter, the arrangement direction A of the louver part is also referred to as an effect axis direction A of the louver film. The viewing angle can be adjusted by the thickness of the louver film, the width of the louver part and the light transmission part, and / or the inclination angle c of the louver part. Although not shown, the louver film may further include a base material layer on one side or both sides of the louver layer as necessary.

  Preferably, the louver film 30 is in close contact with the liquid crystal panel 20 (substantially the viewing-side polarizing plate 21) via any appropriate pressure-sensitive adhesive or adhesive. By closely attaching the louver film to the liquid crystal panel, it is possible to eliminate the air layer and reduce the interface reflection caused by the air layer. As a result, a high-brightness liquid crystal display device can be obtained.

  The thickness of the louver layer 31 can be set to any appropriate thickness depending on the purpose of use. For example, in a case where the viewing angle needs to be more restricted, the louver film may be thickened. The thickness of the louver film is preferably 100 μm to 1000 μm, more preferably 150 μm to 600 μm.

  The width a of the louver part 3 is preferably 1 μm to 100 μm, more preferably 3 μm to 30 μm. The wider the louver part, the more limited the viewing angle. The width of each louver part may be the same or different. The width b of the light transmission part 4 is preferably 50 μm to 500 μm, more preferably 70 μm to 200 μm. The width of the light transmission part is preferably wider than the width of the louver part. The width of each light transmission part may be the same or different.

  The inclination angle c of the louver part 3 is preferably 45 ° to 90 ° (90 ° in FIG. 3A and about 60 ° in FIG. 3B). As the inclination angle of the louver portion is smaller, the viewing angle is limited. In addition, the inclination angle of each louver part may be the same, and may differ.

  For example, a resin having a high visible light transmittance is preferably used as the material constituting the light transmission portion. Examples of such materials include cellulose resins such as cellulose acetate butyrate and triacetyl cellulose; polyolefins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate; silicone resins, polystyrene resins, polyurethane resins, Examples thereof include polyvinyl chloride resin, acrylic resin, and polycarbonate resin. Examples of the material constituting the louver part include a material in which a light shielding substance is contained in the material constituting the light transmission part. Examples of the light-shielding substance include dark pigments such as carbon black, dark dyes, metals, and metal oxides.

  As a method for manufacturing the louver layer, for example, after a material constituting the light transmission portion and a material constituting the louver portion are alternately laminated, a desired thickness is obtained along a direction (lamination direction) perpendicular to the lamination surface. The method of slicing to become is mentioned. When the louver film is provided with a base material layer, the base material layer is attached to the louver layer via any appropriate adhesive or pressure-sensitive adhesive.

  As described above, the louver film narrows the viewing angle by blocking incident light having a large incident angle. Therefore, the transmitted light is lost by the amount of the blocked light. In the present invention, by arranging the louver film on the viewing side of the prism sheet with the convex portion disposed on the back side, the incident angle of light incident on the louver film is reduced in advance and is blocked by the louver film. Less light. As a result, a liquid crystal display device capable of high luminance display with low power consumption can be provided.

  The effective axis direction A of the louver film (that is, the direction in which the louver portions are arranged) is preferably substantially parallel to the direction in which the half-value angle of the emitted light from the prism sheet is minimized. For example, as shown in FIG. 1, when the prism sheet 10 is configured by arranging a plurality of columnar unit prisms 13, transmitted light in the arrangement direction X of the unit prisms 13 (that is, a direction orthogonal to the ridge line direction). Is most condensed (that is, the half-value angle is the smallest), the louver film 30 may be arranged so that the effect axis direction A is substantially parallel to the arrangement direction X of the unit prisms 13. preferable. With such an arrangement, the amount of light transmitted through the light transmission portion of the louver film is increased, and as a result, a liquid crystal display device with a small amount of light loss, that is, a high luminance can be obtained.

D. Liquid Crystal Panel The liquid crystal panel 20 typically includes a liquid crystal cell 22, a viewing side polarizing plate 21 disposed on the viewing side of the liquid crystal cell, and a back side polarizing plate 23 disposed on the back side of the liquid crystal cell. With. The viewing-side polarizing plate 21 and the back-side polarizing plate 23 can be arranged such that their absorption axes are substantially orthogonal or parallel.

D-1. Liquid Crystal Cell The liquid crystal cell 22 includes a pair of substrates 1 and 1 ′ and a liquid crystal layer 2 as a display medium sandwiched between the substrates. In a general configuration, a color filter and a black matrix are provided on one substrate, a switching element that controls the electro-optical characteristics of the liquid crystal on the other substrate, and a scanning line that supplies a gate signal to the switching element. In addition, a signal line for supplying a source signal, a pixel electrode, and a counter electrode are provided. The distance between the substrates (cell gap) can be controlled by a spacer or the like. For example, an alignment film made of polyimide can be provided on the side of the substrate in contact with the liquid crystal layer.

  In one embodiment, the liquid crystal layer includes liquid crystal molecules that are aligned in a homogeneous alignment in the absence of an electric field. Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a three-dimensional refractive index of nx> ny = nz. In this specification, ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same. Typical examples of drive modes using such a liquid crystal layer exhibiting a three-dimensional refractive index include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode. The IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode using a V-shaped electrode or a zigzag electrode. The FFS mode includes an advanced fringe field switching (A-FFS) mode and an ultra fringe field switching (U-FFS) mode employing a V-shaped electrode or a zigzag electrode.

  In another embodiment, the liquid crystal layer includes liquid crystal molecules aligned in a homeotropic alignment in the absence of an electric field. Such a liquid crystal layer (as a result, a liquid crystal cell) typically exhibits a three-dimensional refractive index of nz> nx = ny. An example of a drive mode using liquid crystal molecules aligned in a homeotropic alignment in the absence of an electric field is a vertical alignment (VA) mode. The VA mode includes a multi-domain VA (MVA) mode.

D-2. Polarizing plate A polarizing plate typically includes a polarizer and protective layers disposed on both sides of the polarizer. The polarizer is typically an absorptive polarizer.

  The transmittance at a wavelength of 589 nm (also referred to as single transmittance) of the absorptive polarizer is preferably 41% or more, more preferably 42% or more. Note that the theoretical upper limit of the single transmittance is 50%. The degree of polarization is preferably 99.5% to 100%, more preferably 99.9% to 100%. If it is said range, the contrast of a front direction can be made still higher when it uses for a liquid crystal display device.

  Any appropriate polarizer is used as the polarizer. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of the polarizer is preferably 0.5 μm to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film is typically produced by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. Is done. Stretching may be performed after dyeing, may be performed while dyeing, or may be performed after stretching. In addition to stretching and dyeing, for example, treatments such as swelling, crosslinking, adjustment, washing with water, and drying are performed.

  Any appropriate film is used as the protective layer. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetyl cellulose (TAC), (meth) acrylic, polyester, polyvinyl alcohol, polycarbonate, polyamide, and polyimide. And transparent resins such as polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be an extruded product of the resin composition, for example.

E. Other members E-1. Backlight Unit The liquid crystal display device of the present invention can include a backlight unit 40 on the back side of the prism sheet 10. In the backlight unit, the backlight unit 40 may be an edge light system or a direct system. FIG. 1 shows an edge light type backlight unit. When the edge light system is adopted, the backlight unit 40 may include a light source 41, a light guide plate 42, and a reflection plate 43. As the light source, for example, an LED light source configured by arranging a plurality of LEDs may be used. The backlight unit 40 may further include a diffusion plate as necessary (not shown). When the unit prism 13 of the prism sheet 10 is columnar, the backlight unit is preferably arranged such that the light source is located on a side substantially parallel to the ridge line direction of the unit prism 13. That is, when the light source is an LED light source, it is preferable that the ridge line direction of the unit prism and the LED arrangement direction are substantially parallel. Moreover, it is preferable that a backlight unit is arrange | positioned so that a light source may be located in the edge | side substantially orthogonal to the effect axis direction of the said louver film. That is, when the light source is an LED light source, it is preferable that the effect axis direction of the louver film and the arrangement direction of the LEDs are substantially orthogonal. With such an arrangement, the amount of light transmitted through the light transmission portion of the louver film is increased, and as a result, a liquid crystal display device with a small amount of light loss, that is, a high luminance is obtained. It should be noted that “substantially orthogonal”, “substantially orthogonal”, and “substantially parallel” also exist in the relationship between the side where the light source is located or the LED arrangement direction and the ridge line direction of the unit prism or the effective axis direction of the louver film. Needless to say, the expressions “substantially parallel” and “angle” encompass angles as described in section B-1. That is, the expression “substantially orthogonal” and “substantially orthogonal” are expressed in two directions also in the relationship between the side where the light source is located or the arrangement direction of the LEDs and the ridge line direction of the unit prism or the effective axis direction of the louver film. Is included, preferably 90 ° ± 7 °, and more preferably 90 ° ± 5 °. The expressions “substantially parallel” and “substantially parallel” include the case where the angle between two directions is 0 ° ± 10 °, preferably 0 ° ± 7 °, more preferably 0 ° ± 5 °. Furthermore, the term “orthogonal” or “parallel” may include a substantially orthogonal state or a substantially parallel state.

  Any appropriate light guide plate may be used as the light guide plate 42. For example, a light guide plate in which a lens pattern is formed on the back side and a light guide plate in which a prism shape or the like is formed on the back side and / or the viewing side are used so that light from the lateral direction can be deflected in the thickness direction. . Preferably, a light guide plate having prism shapes formed on the back side and the viewing side is used. In the light guide plate, the prism shape formed on the back side and the prism shape formed on the viewing side are preferably perpendicular to each other in the ridge line direction. If such a light guide plate is used, light that is more easily condensed can be made incident on the prism sheet, and the effect of the present invention becomes remarkable.

  As the reflection plate 43, for example, a highly reflective resin sheet, a sheet having a metal vapor deposition surface, a metal foil, a metal thin plate, or the like is used. Preferably, a specular reflector such as a sheet having a metal vapor deposition surface, a metal foil, or a metal thin plate is used. Since the specularly reflected light is easily collected by the prism sheet, the effect of the present invention becomes remarkable when a specular reflector is used.

E-2. Reflective Polarizer The liquid crystal display device of the present invention may further include a reflective polarizer. Preferably, the reflective polarizer is disposed between the liquid crystal panel and the prism sheet. The reflective polarizer has a function of transmitting polarized light in a specific polarization state (polarization direction) and reflecting light in other polarization states. The reflective polarizer may be a linearly polarized light separation type or a circularly polarized light separation type.

  In one embodiment, the reflective polarizer is arranged to transmit light having a polarization direction parallel to the transmission axis of the back-side polarizing plate of the liquid crystal cell. That is, the reflective polarizer is arranged so that its transmission axis is substantially parallel to the transmission axis direction of the back-side polarizing plate. With such a configuration, light absorbed by the back-side polarizing plate can be reused, utilization efficiency can be further increased, and luminance can be improved.

  As the reflective polarizer, for example, the one described in JP-T-9-507308 can be used.

  As the reflective polarizer, a commercially available product may be used as it is, or a commercially available product may be used after secondary processing (for example, stretching). As a commercial item, 3M company brand name DBEF and 3M company brand name APF are mentioned, for example.

  The reflective polarizer is bonded to an adjacent member via any appropriate adhesive layer (for example, an adhesive layer or a pressure-sensitive adhesive layer: not shown).

F. Applications The liquid crystal display device of the present invention can be suitably used for applications that require display of images with a narrow viewing angle. Specific examples of preferred applications include a seat monitor, a cash dispenser, a vending machine such as a ticket, a portable terminal, and the like provided on the back of a chair (seat) of a vehicle such as an automobile, a train, a ship, and an aircraft. . Further, the liquid crystal display device of the present invention can be used as a seat monitor in a vehicle, and can also be used by being arranged on the wall, floor or ceiling of the vehicle.

  When the liquid crystal display device of the present invention is used as a seat monitor, a high-luminance image can be viewed at the front position where viewing of the seat monitor is desired, while the image is difficult to be viewed at other positions, and viewing of a person who does not want to view it is possible. Discomfort can be reduced. In addition, since a large number of seats equipped with a seat monitor are usually provided in a vehicle, if the liquid crystal display device of the present invention is used for a seat monitor, the effect of reducing power consumption becomes significant.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. The tests and evaluation methods in the examples are as follows. Unless otherwise specified, “parts” and “%” in the examples are based on weight.

(Light loss by louver film)
A white screen is displayed on the liquid crystal display devices obtained in the examples and comparative examples, and brightness of all directions and polar angles θ0 ° to 80 ° using a conoscope (manufactured by AUTRONIC-MELCHERS, trade name “Conosscope”). Was measured. Moreover, after removing the louver film from the liquid crystal display devices obtained in Examples and Comparative Examples, a white screen was displayed on the liquid crystal display device, and the luminance was measured in the same manner as described above. From the measured luminance, the amount of light loss due to the louver film was calculated by the following formula (1). In Equation (1), L ₁ is the measured luminance of the liquid crystal display device on which the louver film is disposed, L ₀ is the measured luminance of the liquid crystal display device on which the louver film is not disposed, θ is the polar angle, and φ is the azimuth angle. Represents

[Example 1]
In order from the viewing side, a liquid crystal panel (a liquid crystal panel mounted on Sony's product name VAIO S series, configuration: viewing side polarizing plate / TN mode liquid crystal cell / back side polarizing plate), a reflective polarizer, and a prism A laminate including a sheet, a backlight unit (an edge light system including a light guide plate formed with a prism shape, a white PET reflector, and an LED light source), and a laminate on the viewing side of the liquid crystal panel A liquid crystal display device comprising a manufactured louver film (manufactured by Sumitomo 3M, trade name “Security / Privacy Filter”, thickness: 0.6 mm, louver width: 7 μm, light transmission width: 150 μm) did.
As the prism sheet, a prism sheet composed of a base part and a prism part in which a plurality of triangular prism unit prisms are arranged was used. The prism sheet was arranged so that the convex portion was directed to the back side.
The louver film was arranged so that the effect axis direction was parallel to the arrangement direction of the unit prisms, and the effect axis direction was orthogonal to the LED arrangement direction.
The liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Example 2]
In order from the viewing side, a liquid crystal panel (a liquid crystal panel mounted on Sony's product name VAIO Z series, configuration: viewing side polarizing plate / TN mode liquid crystal cell / back side polarizing plate), prism sheet, and backlight unit A laminate comprising (a light guide plate in which a prism shape is formed, an Ag mirror reflector, and an LED light source), and a louver film (Sumitomo) placed on the viewing side of the liquid crystal panel of the laminate A liquid crystal display device having a product name “Security / Privacy Filter” manufactured by 3M Co., Ltd., thickness: 0.6 mm, louver width: 7 μm, light transmission width: 150 μm was prepared.
As the prism sheet, a prism sheet composed of a base part and a prism part in which a plurality of triangular prism unit prisms are arranged was used. The prism sheet was arranged so that the convex portion was directed to the back side.
The louver film was arranged so that the effect axis direction was parallel to the arrangement direction of the unit prisms, and the effect axis direction was orthogonal to the LED arrangement direction.
The liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Example 3]
A liquid crystal display device was prepared in the same manner as in Example 2 except that the louver film was adhered to the viewing side of the liquid crystal panel via an adhesive. This liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Example 4]
A liquid crystal display device was prepared in the same manner as in Example 2 except that the louver film was arranged so that the effect axis direction was orthogonal to the unit prism arrangement direction and parallel to the LED arrangement direction. . This liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Comparative Example 1]
In order from the viewing side, a liquid crystal panel (a liquid crystal panel mounted on a product name MacBookPro retina manufactured by Apple Inc., configuration: viewing side polarizing plate / IPS mode liquid crystal cell / back side polarizing plate), a first diffusion sheet, 1 prism sheet, 2nd prism sheet, 2nd diffusion sheet, backlight unit (light guide plate on which hemispherical lens is formed, white PET reflector, and LED light source) And a louver film (trade name “Security / Privacy Filter”, manufactured by Sumitomo 3M Ltd., thickness: 0.6 mm, width of the louver part: 7 μm) placed on the viewing side of the liquid crystal panel of the laminate. And a liquid crystal display device having a light transmission part width of 150 μm).
As the first and second prism sheets, prism sheets each including a base material portion and a prism portion in which a plurality of triangular prisms are arranged are used. The prism sheet was arranged so that the convex portion was directed to the viewing side. Further, the first prism sheet and the second prism sheet were arranged so that their arrangement directions were orthogonal.
The louver film was arranged so that the effect axis direction was parallel to the arrangement direction of the first unit prisms, and the effect axis direction was orthogonal to the LED arrangement direction.
The liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Comparative Example 2]
In order from the viewing side, a liquid crystal panel (a liquid crystal panel mounted on a product name iPad2 manufactured by Apple Inc., configuration: viewing side polarizing plate / IPS mode liquid crystal cell / back side polarizing plate), a reflective polarizer, Diffusion sheet, first prism sheet, second prism sheet, second diffusion sheet, backlight unit (light guide plate on which hemispherical lens is formed, white PET reflector, LED light source, And a louver film (trade name “Security / Privacy Filter”, manufactured by Sumitomo 3M Ltd., thickness: 0.6 mm, louver) placed on the viewing side of the liquid crystal panel of the laminate. Part width: 7 μm and light transmission part width: 150 μm).
As the first and second prism sheets, prism sheets each including a base material portion and a prism portion in which a plurality of triangular prisms are arranged are used. The prism sheet was arranged so that the convex portion was directed to the viewing side. Further, the first prism sheet and the second prism sheet were arranged so that their arrangement directions were orthogonal.
The louver film was arranged so that the effect axis direction was parallel to the arrangement direction of the first unit prisms, and the effect axis direction was orthogonal to the LED arrangement direction.
The liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

[Comparative Example 3]
The liquid crystal display device is the same as Comparative Example 2 except that the louver film is arranged so that the effect axis direction is orthogonal to the arrangement direction of the first unit prisms and parallel to the LED arrangement direction. Prepared. This liquid crystal display device was subjected to the evaluation (1). The results are shown in Table 1.

  As is apparent from Table 1, the liquid crystal display device of the present invention including the prism sheet and the louver film that are convex on the back side has a small amount of light loss due to the arrangement of the louver film. Further, as is clear from the comparison between Example 1 and Example 2, the amount of light loss can be further reduced by using a backlight unit including a specular reflector. Such an effect is considered to be obtained because the specularly reflected light is more easily collected on the prism sheet. Further, as is clear from the comparison between Example 2 and Example 3, the amount of light loss is further reduced when the louver film is brought into close contact with the liquid crystal panel. This is considered to be because the air layer between the louver film and the liquid crystal panel is not formed, and the influence of the interface reflection is reduced.

  As is clear from the comparison between Example 2 and Example 4, the amount of light loss is reduced if the effective axis direction of the louver film is orthogonal to the arrangement direction of the LED light sources. If the louver film is arranged so that the effect axis direction is parallel to the arrangement direction of the unit prisms, the amount of light loss is reduced. With such an arrangement, it is considered that the amount of light transmitted through the light transmission portion of the louver film increases, and as a result, a liquid crystal display device with a small amount of light loss, that is, a high luminance can be obtained. On the other hand, when a prism sheet having a convex portion on the viewing side is used as in the comparative example, since the light collecting effect by the prism sheet is small, the correlation between the arrangement direction of the louver film and the amount of light loss becomes small. Conceivable.

10 prism sheet 20 liquid crystal panel 30 louver film 40 backlight unit 100 liquid crystal display device

Claims (8)

A louver film, a liquid crystal panel, and a prism sheet are provided in this order from the viewing side,
The prism sheet has a convex portion on the side opposite to the viewing side,
Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the louver film is in close contact with the liquid crystal panel.   3. The liquid crystal display device according to claim 1, wherein an effective axis direction of the louver film is substantially parallel to a direction in which a half-value angle of light emitted from the prism sheet is smallest.   The liquid crystal display device according to claim 1, wherein the prism sheet includes a plurality of triangular prism unit prisms arranged in parallel.   The liquid crystal display device according to claim 1, further comprising a backlight unit including a light source, a light guide plate, and a specular reflection plate.   The liquid crystal display device according to claim 5, wherein the light guide plate is a light guide plate in which prism shapes are formed on a back side and a viewing side. The prism sheet is formed by arranging a plurality of triangular prism unit prisms in parallel,
The liquid crystal display device according to claim 5, wherein a light source of the backlight unit is disposed on a side substantially parallel to the ridge line direction of the unit prism.   The liquid crystal display device according to claim 5, wherein a light source of the backlight unit is disposed on a side substantially perpendicular to the direction of the effect axis of the louver film.

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