JP2012118223A - Protective film, polarizing plate, liquid crystal display panel, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems caused by an optical sheet disposed in a light-incident side of a protective film.SOLUTION: A protective film 50 is joined to a light-incident side of a polarizer 41 to constitute a polarizing plate 40 in a light-incident side of a liquid crystal display panel. The protective film 50 for the polarizing plate in the light-incident side has a light-diffusing layer 51a containing a base part 59a made of a resin material and a diffusion component 59b dispersed in the base part 59a. The diffusion component 59b of the light-diffusing layer 51a has refractive index isotropy, while the base part 59a of the light diffusing layer 51a has refractive index anisotropy.

Description

  The present invention relates to a protective film for a polarizing plate which is bonded to a polarizer from the light incident side to form a light incident side polarizing plate for a liquid crystal display panel. Moreover, this invention relates to the polarizing plate containing such a protective film, and the liquid crystal display panel and display apparatus containing this polarizing plate.

  Nowadays, an optical module having a polarizing plate including a polarizer and a light emitter arranged at a position facing the polarizing plate is used by being incorporated in an optical device. As a typical use example, the optical module is used in a display device, particularly a liquid crystal display device. The liquid crystal display device includes a liquid crystal display panel and a surface light source device that functions as a backlight that illuminates the liquid crystal display panel.

  As shown in FIG. 16, the surface light source device includes a light source including a light emitter and a large number of optical sheets for changing the traveling direction of light from the light emitter, and liquid crystal with desired optical characteristics. Designed to illuminate the display panel. In the example of the surface light source device shown in FIG. 16, a diffusion plate A, a lower diffusion sheet B, a condensing sheet C, and an upper diffusion sheet D are provided in order from the light emitter 26 side of the light source 25. Among these, the condensing sheet C has the function (condensing function) which narrows the advancing direction of light to the front direction and improves the luminance in the front direction. On the other hand, the diffusing plate A, the lower diffusing sheet B, and the upper diffusing sheet D have a light diffusing function of diffusing light from the illuminant 26 of the light source 25 to hide the image of the illuminant 26 (make it inconspicuous). .

  On the other hand, as shown in FIG. 16, the liquid crystal display panel includes a liquid crystal cell 11 capable of controlling the orientation of liquid crystal molecules for each pixel, a lower polarizing plate 13 disposed on the light incident side of the liquid crystal cell, and a liquid crystal And an upper polarizing plate 12 disposed on the light output side of the cell 11. The pair of polarizing plates 12 and 13 is a polarizer that transmits light of a specific polarization component and absorbs light of components other than the specific polarization component, and is bonded to the polarizer from the light incident side or the light output side. And a protective film for protecting.

  Of these, the protective film is usually formed as a simple translucent film due to cost constraints, and does not positively affect the transmitted light. In addition, a protective film with an optical function does not exist, but considering the adhesive function with the polarizer and the protective function to protect the polarizer, the protective film on the side that does not actually face the polarizer The surface is merely a mat surface (for example, Patent Document 1).

  However, a sufficient diffusion function cannot be imparted to the protective film to the extent that one surface of the protective film is matted. For this reason, as shown in FIG. 16, in the conventional display apparatus, it was necessary to provide many optical sheets on the light incident side of the protective film of the polarizing plate.

Japanese Patent Laid-Open No. 9-258013

  However, various problems arise due to the surface light source device (display device) including a large number of optical sheets. First, when the number of optical sheets increases, the thickness of the display device is not simply increased, but the manufacturing cost of the display device directly increases. In addition, when the surface light source device (display device) includes a large number of optical sheets, positioning between the optical sheets performed when the surface light source device is assembled and positioning between the optical sheet and the light emitter are complicated. This also increases the manufacturing cost of the display device.

  Further, each optical sheet does not transmit all incident light, and a part of the incident light is reflected by the optical sheet. The light reflected by the optical sheet can be reflected by the reflecting plate 21 (see FIG. 16) provided on the back surface of the light emitter 26 or another optical sheet and reused. However, part of the light is absorbed each time the light is reflected by each optical sheet. Such reflection loss increases significantly only when the number of optical sheets increases by one. That is, when a surface light source device (display device) includes a large number of optical sheets, the utilization efficiency of light emitted from the light emitter of the light source is significantly reduced.

  Furthermore, the optical sheet is heated by heat generated from the light emitter, and the optical sheet may be bent, bent, warped, or the like. At this time, in a surface light source device (display device) provided with a large number of optical sheets, adjacent optical sheets may contact or rub against each other. The portion where the optical sheets are in close contact with each other can no longer exhibit the expected optical function, and the close contact portion may be visually recognized. In addition, when the optical sheets are rubbed with each other, the optical sheets may be scratched, and further, residue may be generated, and the display image quality is remarkably deteriorated.

  The present invention has been made in consideration of such points, and an object thereof is to cope with a problem caused by the optical sheet provided on the light incident side of the protective film.

The protective film according to the present invention is
A protective film for a polarizing plate that is joined to a polarizer from the light incident side to form a light incident side polarizing plate for a liquid crystal display panel,
A light diffusion layer including a base material portion made of a resin material and a diffusion component dispersed in the base material portion;
The diffusion component of the light diffusion layer has a refractive index isotropic property,
The base material portion of the light diffusion layer has refractive index anisotropy.

  In the protective film according to the present invention, the light diffusion layer may be formed by uniaxially stretching the resin material forming the base material portion in which fine particles are dispersed. In this way, in the protective film according to the present invention, the light diffusion layer may be formed by extruding and uniaxially stretching the resin material forming the base material part in which fine particles are dispersed.

  In the protective film according to the present invention, the refractive index of the diffusing component may be equal to or lower than the refractive index of the fast axis of the base material portion.

  The protective film according to the present invention may further include a plurality of unit optical elements that form a light incident side surface, that is, a surface opposite to the surface facing the polarizer of the protective film.

  In the protective film according to the present invention, the plurality of unit optical elements may be arranged in a predetermined arrangement direction, and each unit optical element may extend in a direction intersecting with the arrangement direction of the plurality of unit optical elements. Good.

  The protective film according to the present invention may further include a resin layer in which the diffusion component is not dispersed. Moreover, in such a protective film according to the present invention, the light diffusion layer may be disposed on the light output side, that is, on the polarizer side, with respect to the resin layer.

  In the protective film according to the present invention, there may be no optical interface between the base material portion of the light diffusion layer and the resin layer.

  In the protective film according to the present invention, the light incident side surface, that is, the surface opposite to the side facing the polarizer, may be provided with unevenness formed due to the presence of the diffusing component. .

  In the protective film according to the present invention, unevenness formed by shaping may be provided on the light incident side surface, that is, the surface opposite to the side facing the polarizer.

  In the protective film according to the present invention, the haze value may be 60% or more and 90% or less.

In the protective film according to the present invention, the moisture permeability at a temperature of 40 ° C., a humidity of 90% RH, and 24 hours may be 10 g / m ² · 24 hr or more.

The polarizing plate according to the present invention is
A polarizing plate on the light incident side for a liquid crystal display panel,
A polarizer,
A protective film according to the present invention as described above, comprising a protective film bonded to the polarizer from the light incident side.

  In the polarizing plate according to the present invention, the fast axis of the base portion of the light diffusion layer may be parallel to the transmission axis of the polarizer.

  The polarizing plate according to the present invention may further include an intermediate film disposed between the protective film and the polarizer.

  In the polarizing plate according to the present invention, the polarizing plate may further include an adhesive layer disposed between the protective film and the polarizer. In the polarizing plate according to the present invention, the adhesive layer may include an adhesive and a diffusion component dispersed in the adhesive.

  The liquid crystal display panel according to the present invention includes any of the polarizing plates according to the present invention described above.

  The liquid crystal display panel according to the present invention further comprises a liquid crystal cell laminated on the polarizing plate from the light exit side and having a pixel arrangement, and the protective film forms a light incident side and is arranged in a predetermined arrangement direction. When the plurality of unit optical elements are arranged and observed from a direction parallel to the normal direction to the plate surface of the polarizing plate, the alignment direction of the plurality of unit optical elements of the protective film is It may intersect with the pixel array.

A display device according to the present invention includes any one of the above-described liquid crystal display panels according to the present invention.
A light emitter that illuminates the liquid crystal display panel from the protective film side.

  In the display device according to the present invention, the light emitter may be arranged at a position facing the protective film of the deflection plate.

  In the display device according to the present invention, when observed from a direction parallel to a normal direction to the plate surface of the polarizing plate, the plurality of unit optical elements are arranged in a direction parallel to the arrangement direction of the light emitters. May be.

  According to this invention, the light-diffusion layer of the protective film joined to a polarizer from the light-incidence side has a diffusion component. For this reason, the optical sheet having a diffusion function that has been provided as an independent layer on the light incident side of the protective film can be deleted, and problems caused by the optical sheet can be prevented. . According to the invention, among the constituent components of the light diffusing layer, the diffusing component has a refractive index isotropic property, and the base material portion has a refractive index anisotropy. Thereby, a protective film expresses refractive index anisotropy between the predetermined direction and the direction orthogonal to this, and, thereby, exhibits an anisotropic diffusion function. For this reason, it becomes unnecessary to diffuse the light incident on the protective film more than necessary, and the light can be effectively used. Furthermore, according to this invention, since the light-diffusion layer of a protective film contains the base material part which has refractive index anisotropy, a polarization separation function can be provided to a protective film.

FIG. 1 is a perspective view showing a schematic configuration of a display device and an optical module for explaining an embodiment according to the present invention. FIG. 2 is a perspective view showing a polarizing plate (lower polarizing plate) incorporated in the optical module of FIG. FIG. 3 is a diagram for explaining the operation of the display device and the optical module according to the embodiment of the present invention, and shows the display device and the optical module in a cross section taken along the line III-III of FIG. is there. FIG. 4 is a perspective view showing a protective film incorporated in the optical module of FIG. FIG. 5 is a diagram showing diffusion components contained in the protective film of FIG. FIG. 6 is a diagram for explaining an example of a protective film manufacturing method and a protective film manufacturing apparatus for a polarizing plate (lower polarizing plate) according to an embodiment of the present invention. FIG. 7 is a diagram corresponding to FIG. 1 for explaining a modification of the light emitter of the light source according to the embodiment of the present invention. FIG. 8 is a view showing the polarizing plate in the same cross section as FIG. 3, and is a view for explaining a modification of the protective film according to the embodiment of the present invention. FIG. 9 is a view showing the polarizing plate in the same cross section as FIG. 3, and is a view for explaining another modified example of the protective film according to the embodiment of the present invention. FIG. 10 is a view showing the liquid crystal display panel in the same cross section as FIG. 3, and is a view for explaining still another modified example of the protective film according to the embodiment of the present invention. FIG. 11 is a view showing the liquid crystal display panel in the same cross section as FIG. 3, and is a view for explaining still another modified example of the protective film according to the embodiment of the present invention. FIG. 12 is a view showing the liquid crystal display panel in the same cross section as FIG. 3, and is a view for explaining still another modification of the protective film according to the embodiment of the present invention. FIG. 13 is a view showing the polarizing plate in the same cross section as FIG. 3, and is a view for explaining still another modified example of the protective film according to the embodiment of the present invention. FIG. 14 is a view showing the polarizing plate in the same cross section as FIG. 3, and is a view for explaining still another modification of the protective film according to the embodiment of the present invention. FIG. 15 is a longitudinal sectional view showing the display device and the optical module, and is a view for explaining a modification of the display device and the optical module according to the embodiment of the present invention. FIG. 16 is a perspective view corresponding to FIG. 1 and showing a conventional display device. FIG. 17 is a cross-sectional view corresponding to FIG. 15 and showing a conventional display device.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones.

  FIGS. 1-6 is a figure for demonstrating one Embodiment by this invention. Among these, FIG. 1 is a perspective view showing a schematic configuration of the display device and the optical module. FIG. 2 is a perspective view showing a polarizing plate of the optical module, and FIG. 3 is a diagram for explaining the operation of the optical module. FIG. 4 is a perspective view showing a protective film, FIG. 5 is a view showing a diffusing component, and FIG. 6 is a view for explaining a method for producing a protective film included in a polarizing plate of an optical module. .

  The display device 10 shown in FIG. 1 is a liquid crystal display device, and is disposed on the liquid crystal display panel 15 and the back side of the liquid crystal display panel 15 (the side opposite to the observer side, the side of a protective film 50 described later). Light source 25, and reflector 21 that covers light source 25 from the back side. The light source 25 includes a plurality of light emitters 26 and illuminates the liquid crystal display panel 15 from the back side. On the other hand, the liquid crystal display panel 15 functions as a shutter that controls transmission or blocking of light emitted from the light emitter 26 of the light source 25 for each pixel, and forms an image.

  As will be described in detail later, the liquid crystal display panel 15 includes a pair of polarizing plates 12 and 40 and a liquid crystal cell 11 disposed between the pair of polarizing plates. The optical module 20 is formed by the polarizing plate 40 on the light incident side of the pair of polarizing plates of the liquid crystal display panel 15 and the light emitter 26 that forms the light source 25. In the following, in order to distinguish a pair of polarizing plates included in the liquid crystal display panel 15, the light incident side polarizing plate 40 is referred to as a lower polarizing plate regardless of the arrangement state of the display device 10, and the light emitting side polarized light. The plate 12 is called an upper polarizing plate.

  The display device 10 is configured as a direct-type liquid crystal display device, and a light emitter 26 forming a light source 25 is disposed at a position facing the liquid crystal display panel 15 in the front direction nd (see FIG. 3). . That is, the light emitter 26 that constitutes the light source 25 is arranged at a position facing the lower polarizing plate 40 located on the most incident light side of the liquid crystal display panel 15 and the front direction nd. Therefore, no other member is interposed between the light emitter 26 forming the light source 25 and the lower polarizing plate 40 located on the most incident light side of the liquid crystal display panel 15, and the light emitter 26 emits light. The light directly enters the lower polarizing plate 40.

  Various known light emitters such as cold cathode fluorescent lamps can be used as the light emitter 26 forming the light source 25. However, in the illustrated example, the light source 25 is configured by a plurality of light emitting diodes (LEDs) 26. As can be understood from FIG. 1, the multiple light emitters 26 are two-dimensionally arranged on a virtual plane. That is, a large number of light emitters 26 are not arranged in only one direction on the virtual plane but are arranged with a planar spread. In particular, in the example shown in FIG. 1, the light emitters 26 forming the light source 25 are arranged in the first arrangement direction d1 and also arranged in the second arrangement direction d2 orthogonal to the first arrangement direction. Thus, they are arranged on lattice points (the center of the light emitter 26 is arranged on a square lattice or a rectangular lattice).

  The reflecting plate 21 is a member for directing light emitted from the light emitter 26 of the light source 25 toward the liquid crystal display panel 15. At least the inner surface of the reflecting plate 21 is made of a material having a high reflectance such as metal.

  In the present specification, the “light exit side” refers to the downstream side in the traveling direction of light from the light emitter 26 of the light source 25 to the observer through the liquid crystal display panel 15 without wrapping the traveling direction (observer side, In FIG. 1, the “light-incident side” is the direction in which the light travels from the light emitter 26 of the light source 25 to the viewer through the liquid crystal display panel 15 without being folded back. It is upstream.

  Further, in the present specification, the terms “sheet”, “film”, and “plate” are not distinguished from each other only based on the difference in names. Therefore, for example, a “sheet” is a concept including a member that can also be called a film or a plate. As a specific example, the “protective film” includes a member called a “protective sheet”.

  Further, in this specification, the “sheet surface (film surface, plate surface)” is the same as the planar direction of the target sheet-like member when the target sheet-like member is viewed as a whole and globally. It refers to the surface to be used. And in this Embodiment, the panel surface of the liquid crystal display panel 15, the plate surface of the lower polarizing plate 40, the film surface of the protective film 50 mentioned later, etc. are mutually parallel. Further, in the present specification, the “front direction” refers to a direction parallel to the normal direction nd to the display surface 10a of the display device 10, and in this embodiment, the plate surface of the lower polarizing plate 40. It is parallel to the normal direction.

  Further, terms used in the present specification for specifying shapes and geometric conditions, for example, terms such as “parallel”, “orthogonal”, and “symmetric” are not limited to strict meanings, Interpretation will be made including errors to the extent that an expected function can be expected.

  Next, the liquid crystal display panel 15 will be described. As described above, the liquid crystal display panel 15 includes the pair of polarizing plates 12 and 40 and the liquid crystal cell 11 disposed between the pair of polarizing plates 12 and 40. Among these, the polarizing plates 12 and 40 have a function (absorption type polarization separation function) of decomposing incident light into orthogonal polarization components, transmitting one polarization component, and absorbing the other polarization component. Yes.

  On the other hand, the liquid crystal cell 11 has a pair of transparent substrates made of glass or the like, and a liquid crystal layer provided between the transparent substrates. An electric field can be applied to the liquid crystal layer for each region where one pixel is formed. Then, the orientation of the liquid crystal molecules in the liquid crystal layer applied with an electric field changes. For example, the polarization component in a specific direction (direction parallel to the transmission axis) transmitted through the lower polarizing plate 40 disposed on the light incident side passes through a region of the liquid crystal layer to which an electric field is applied in the liquid crystal cell 11. At that time, the polarization direction is rotated by 90 °, and the polarization direction is maintained when passing through the liquid crystal layer to which no electric field is applied. For this reason, depending on whether or not an electric field is applied to each region of the liquid crystal layer, whether the polarization component in a specific direction transmitted through the lower polarizing plate 40 is further transmitted through the upper polarizing plate 12 disposed on the light output side of the lower polarizing plate 40. Alternatively, it is possible to control whether the light is absorbed and blocked by the upper polarizing plate 12.

  Here, with reference to FIG. 2 and FIG. 3, the lower polarizing plate 40 for the liquid crystal display panel 15 will be described in further detail. The lower polarizing plate 40 includes a polarizer 41 that can exhibit an absorption polarization separation function, and a protective film 50 bonded (adhered) to the polarizer 41 from the light incident side. As shown in FIG. 3, the protective film 50 is laminated on the polarizer 41 from the side that does not face the liquid crystal cell 11, in other words, from the light incident side, and protects the polarizer 41 from the outside.

  Further, an adhesive layer (not shown) is provided between the polarizer 41 and the protective film 50 so as to be adjacent to the polarizer 41 and the protective film 50 and adheres the polarizer 41 and the protective film 50 to each other. It may be. The adhesive layer for improving the adhesion between the polarizer 41 and the protective film 50 can be formed using various conventional adhesives. As one specific example, for example, an adhesive layer can be formed using an aqueous adhesive mainly composed of a polyvinyl alcohol-based resin. In addition, the adhesion in this specification is a concept including adhesion and gluing, and similarly, the adhesive in this specification is a concept including pressure-sensitive adhesive and glue.

  Various polarizers have been developed to date, and any of these polarizers can be used as the polarizer 41. As a specific example, a polarizer 41 having a polyvinyl alcohol film as a base material can be used. The polarizer 41 based on a polyvinyl alcohol film is an anisotropic material that absorbs or dyes a dichroic dye such as iodine or dye on a polyvinyl alcohol film, and then aligns the film by uniaxial stretching. Can be imparted to the polyvinyl alcohol film.

  Next, the protective film 50 will be described. The protective film 50 described here has a light control function that changes the traveling direction of light. As a specific configuration, the protective film 50 includes a plurality of unit optical elements 60 that form a light incident side surface (a surface opposite to the side facing the polarizer 41 of the protective film 50). That is, the light incident side surface 50b of the protective film 50 is an optical element surface (prism surface) formed by unit optical elements (unit prisms) 60 arranged side by side, as well shown in FIGS. It is configured. By this optical element surface, the protective film 50 exhibits a light collecting function.

  Further, the protective film 50 includes a light diffusion layer 51a including a base material portion 59a having refractive index anisotropy and a diffusion component 59b having refractive index isotropic property dispersed in the base material portion 59a. As a result, the protective film 50 exhibits a polarization separation function and an anisotropic light diffusion function. Hereinafter, the configuration of the protective film 50 will be further described in detail.

  The “unit optical element” in the present specification refers to an element having a function of changing the traveling direction of the light by exerting an optical action such as refraction or reflection on the light. ”,“ Unit prism ”, and“ unit lens ”are not distinguished based only on the difference in designation and elements. Similarly, “prism” and “lens” are not distinguished from each other based solely on the difference in designation.

  As well shown in FIG. 3, the protective film 50 includes a sheet-like main body portion 55 and unit optical elements 60 arranged side by side on the light incident side surface 55 b of the main body portion 55. Each unit optical element 60 extends in a direction intersecting the arrangement direction and parallel to the film surface of the protective film 50. Further, the unit optical elements 60 included in the protective film 50 are configured identically. In the present embodiment, when observed from a direction parallel to the normal direction to the plate surface of the lower polarizing plate 40, the arrangement direction of the unit optical elements 60 is the first arrangement direction d1 of the plurality of light emitters 26 (FIG. 1)).

  By the way, the liquid crystal display panel 15 defines a large number of pixels. The liquid crystal display panel 15 forms an image by controlling transmission and blocking of light for each pixel. When the unit optical elements 60 are observed from a direction parallel to the direction normal to the plate surface of the lower polarizing plate 40, the unit optical elements 60 intersect with the pixel arrangement direction of the liquid crystal cell 11 of the liquid crystal display panel 15, that is, It is preferable to be inclined or orthogonal to the pixel arrangement direction. Specifically, when observed from a direction parallel to the direction normal to the plate surface of the lower polarizing plate 40, the arrangement direction of the unit optical elements 60 and the arrangement direction of the pixels of the liquid crystal cell 11 are 1 ° or more and 45 °. It is preferable to incline at an angle of less than 0 °, more preferably at an angle of 2 ° to 15 °. In this case, moire (interference fringes) caused by interference between the periodicity caused by the regular arrangement of the pixels and the periodicity caused by the regular arrangement of the unit optical elements 60 can be effectively made inconspicuous. it can. From the viewpoint of making the moire inconspicuous, it is preferable that the arrangement pitch of the unit optical elements 60 is 30 μm or less. It should be noted that the arrangement pitch needs to be sufficiently larger than the maximum visible light wavelength of 0.78 μm in order to exhibit light condensing or diffusing properties due to geometric optical refraction or reflection, and is usually set to 5 μm or more.

  The cross section shown in FIG. 3 is a cross section (hereinafter also simply referred to as “main cut surface”) along both the arrangement direction of the unit optical elements 60 and the normal direction to the film surface of the protective film 50. As shown in FIG. 3, each unit optical element 60 has a triangular shape on the main cutting plane. In particular, in the illustrated example, the cross-sectional shape of the main cutting surface of the unit optical element 60 is an isosceles triangle that is arranged symmetrically about the normal direction to the film surface of the protective film 50. The angle θa (see FIG. 3) of the isosceles triangle shape can be set to, for example, 15 ° to 100 ° in consideration of the light collecting function and the diffusion function. In particular, θa is preferably 30 ° or more and 70 ° or less.

  Further, the diffusion component 59b of the protective film 50 has a refractive index isotropic property. On the other hand, as described later, the surrounding base material portion 59a in contact with the diffusion component 59b has refractive index anisotropy. Due to the interaction between the diffusion component 59b and the base material portion 59a, the protective film 50 exhibits an anisotropic light diffusion function. As an example, as shown in FIG. 4, the diffusion component 59 b having the longitudinal direction ld may be arranged in the protective film 50 so as to have an orientation in a predetermined direction od. Here, the longitudinal direction of the diffusion component 59b can be specified as a direction in which the length or diameter of the diffusion component 59b as a target becomes the longest. Further, “the diffusion component 59b having the longitudinal direction ld has an orientation in the predetermined direction od” means that the angle formed by the longitudinal direction ld of each diffusion component 59b with respect to the predetermined direction od is 0 ° or more and 45 This means that the diffusion component 59b is arranged with directional regularity with reference to the predetermined direction od. When the longitudinal direction ld has a different distribution for each diffusion component 59b, the statistical average value of each longitudinal direction 59b is defined as the longitudinal direction ld for the diffusion component (whole). In the example shown in FIGS. 2 and 4, as will be described later, the orientation direction of the diffusion component 59b, that is, the longitudinal direction of the diffusion component 59b is the same as that of the linear unit optical elements 60 arranged in parallel. It is parallel to the longitudinal direction. Further, in FIG. 3 and FIGS. 8 to 14 described later, the diffusion component 59b is illustrated in a simplified manner.

  As well shown in FIGS. 3 and 4, the protective film 50 in the present embodiment includes the light diffusion layer 51 a described above and the resin layer 51 b that does not contain the diffusion component 59 b. . In the illustrated example, the resin layer 51b is disposed on the light incident side with respect to the light diffusion layer 51a. That is, the light diffusion layer 51a is disposed closer to the polarizer 41 than the resin layer 51b.

  The base material part 59a of the light diffusion layer 51a has refractive index anisotropy. Such refractive index anisotropy is obtained by extruding a resin material forming the base material portion 59a in which the fine particles 58a are dispersed and uniaxially stretching in the x direction, as shown in FIGS. It is done. Thus, refractive index anisotropy is imparted to the base material portion 59a of the light diffusion layer 51a, and the base material portion 59a has a fast axis with a relatively small refractive index and a slow axis with a relatively large refractive index. To come to have. In general, there are both a material whose stretching direction is the slow axis and a material whose stretching direction is the fast axis, but in the case of general-purpose resin materials, the stretching direction is usually different. In general, the refractive index increases relative to the direction and becomes a slow axis. 4 and 5 also has the slow axis in the stretching direction (x direction). Further, the fast axis of the base material portion 59 a is arranged to be parallel to the transmission axis of the polarizer 41. The parallel here is not limited to a strict meaning, but an error to the extent that a similar optical function can be expected, that is, between the fast axis of the substrate portion 59a and the transmission axis of the polarizer 41. Interpretation will include up to an error in the range where the angle is ± 5 °. 4 and 5, the x direction indicates the stretched direction, the y direction indicates a direction that is not stretched and is orthogonal to the x direction, and the z direction indicates the light diffusion layer 51 a. The thickness direction is shown.

  Further, as shown in FIG. 5, by uniaxially stretching the resin material in which the fine particles 58a are dispersed in this way, a spheroid-shaped void portion 58b is formed around the fine particles 58a and faces the x direction. A diffusion component 59b having a longitudinal direction ld is obtained. The longitudinal direction ld of the diffusion component 59b obtained in this way is parallel to the slow axis of the base material portion 59a.

That is, the diffusing component 59b includes fine particles 58a and voids 58b formed around the fine particles 58a. The ratio of the diffusion component 59b dispersed in the base material portion 59a is expressed as a density per unit area when viewed in plan (when observed from a direction parallel to the normal direction to the plate surface of the polarizing plate 41). For example, 10 to 3000 per 1 cm ² is preferable in plan view.

  As shown in FIG. 5, the gap 58b may exist in a part of the periphery of the fine particles 58a, but may exist in the entire periphery of the fine particles 58a. Further, since the gap 58b acts as an air layer, its refractive index is approximately 1, and its refractive index is isotropic with no dependency on the x, y, and z directions of the three-dimensional space. It is. That is, the refractive index of the gap portion 58b of the diffusing component 59b is equal to or lower than the refractive index of the fast axis of the base material portion 59a of the light diffusion layer 51a, and the gap portion 58b has a refractive index isotropic property. . For example, the difference in refractive index between the base portion 59a and the gap portion 58b of the diffusing component 59b is preferably about 0.3 to 0.7.

  The fine particles 58a preferably have the same refractive index as that of the base material portion 59a of the light diffusion layer 51a as much as possible. As a result, when the light incident on the light diffusion layer 51a passes through the interface between the fine particles 58a and the base material portion 59a, the electric field vector vibrates in the y direction orthogonal to the stretching axis, that is, the fast axis direction. The refractive index difference between the diffusing component 59b and the base material portion 59a with respect to the polarization component is minimized, thereby increasing the transmittance for the polarization component oscillating in the fast axis direction (reducing the reflectance). On the other hand, the refractive index of the base material portion 59a in the stretching direction (x direction) is higher than that in the unstretched direction, and the stretching direction becomes the slow axis. Since the diffusion component 59b is selected to have a refractive index isotropic (refractive index in the x direction nx = refractive index ny in the y direction), the refractive index difference at the interface between the base material portion 59a and the diffusion component 59b is: Inevitably, the polarization component that vibrates in the stretching direction, that is, the slow axis direction has a large refractive index difference at the interface, so that the reflectance increases and the transmittance decreases. In addition, since the refraction angle becomes large with respect to the polarization component, light diffusion can be effectively expressed, and the amount of light that can be transmitted per unit solid angle in a specific direction also decreases. In addition, the shape of the fine particles 58a is not particularly limited, but generally, a spherical shape such as a spherical shape, a spheroid, or a polyhedron with rounded corners is advantageous in terms of availability. As the average particle diameter of the fine particles 58a, those within the range of 3 μm to 20 μm are preferably used. The average particle size at this time is obtained by observing the cross section of the light diffusion layer 51a with a microscope, and is represented by an average value of 50 or more measurement materials.

  The resin layer 51 b constitutes the unit optical element 60 described above and the light incident side portion of the main body portion 55. On the other hand, the light diffusion layer 51a constitutes a part on the light output side of the main body 55 adjacent to the resin layer 51b. The resin layer 51b can be formed by applying a resin, for example, ionizing radiation, on the uniaxially stretched light diffusion layer 51a and molding (molding) it into a desired shape. As a result, there is no optical interface between the base material portion 59a of the light diffusion layer 51a and the resin layer 51b. That is, light enters the protective film 50 from the resin layer 51b to the light diffusion layer 51a without being optically affected.

  A transparent resin material is preferably used as the resin material that forms the base portion 59a of the light diffusion layer 51a. Specifically, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, ethylene-terephthalic acid-isophthalic acid copolymer, ethylene glycol-1,4-cyclohexanedimethanol-terephthalic acid copolymer, polymethyl ( Acrylic resins such as (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer (here, “(meth) acrylate "Means acrylate or methacrylate.), Polyolefin resin such as polycarbonate resin, polystyrene resin, polymethylpentene resin, polycycloolefin copolymer, and thermoplastic urethane resin. Resin, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate and other oligomers and / or trimethylolpropane tri (meth) acrylate, epoxy-based monomers, dipentaerythritol hexa (meth) Examples thereof include a resin obtained by curing an ionizing radiation curable resin composed of a (meth) acrylate monomer such as acrylate with electromagnetic radiation such as ultraviolet rays or electron beams. As ionizing radiation, ultraviolet rays, electron beams and the like are used. However, when the refractive index anisotropy is developed by stretching the light diffusion layer 51a, a thermoplastic resin that is softened by heating and easily aligns molecules is preferable.

  As the resin material forming the resin layer 51b, various resin materials having excellent optical characteristics, for example, polycarbonate resins can be used.

  The fine particles 58a may be fine particles having optical transparency and refractive index isotropic properties generally used for optical sheets. For example, styrene resin fine particles, polycarbonate resin fine particles, polyolefin resin fine particles, urethane resin fine particles, silicone Examples thereof include organic fine particles such as resin fine particles, acrylic resin fine particles, MS resin (methacryl-styrene copolymer resin) fine particles, inorganic fine particles such as glass fine particles and glass beads, and one or more of these are contained in the resin. Can be contained. In the case of forming a void 58b as shown in FIG. 5 at the interface between the fine particles 58a and the base material portion 59a at the time of stretching, the surface of the fine particles 58a has the base material portion 59a of the light diffusion layer 51a. It is preferable that a treatment not compatible with the constituent resin material is performed. Accordingly, at the time of the stretching treatment, peeling can be generated at the interface between the fine particles 58a and the resin material forming the base material portion 59a, and the void portion 58b can be easily formed. In addition, when the voids 58b are not formed at the interface between the fine particles 58a and the base material portion 59a during stretching, the surface of the fine particles 58a is not subjected to such incompatible treatment, and more preferably The surface of the fine particles 58a may be subjected to easy adhesion treatment such as corona discharge treatment, plasma treatment, flame treatment, and easy adhesion primer layer coating treatment to reinforce the adhesion with the substrate portion 59a.

  The protective film 50 has an electric field in the slow axis direction of the base material portion 59a due to the light diffusion layer 51a including the refractive index isotropic diffusion component 59b and the base material portion 59a of refractive index anisotropy. Light is diffusively reflected and diffused and transmitted with high efficiency with respect to the oscillating polarization component, while the polarization component with an electric field oscillating in the fast axis direction of the base member 59a is high in a state with little reflection and diffusion. An anisotropic light diffusion function accompanied by a polarization separation function that transmits light efficiently can be exhibited. The degree of the anisotropic light diffusing function of the protective film 50 due to the internally added diffusion component 59b is determined by the refractive index anisotropy (or the refractive index isotropic property) of the resin material forming the base material portion 59a and the diffusion component 59b. ), The thickness of the base material portion 59a, the configuration (shape, size (particle size), refractive index, etc.) of the diffusion component 59b, specifically, the size of the fine particles 58a, the draw ratio of the light diffusion layer 51a, etc. ), By appropriately setting the concentration of the diffusion component 59b, etc., it can be adjusted within a very wide range. Specifically, the haze value of the protective film 50 is set to a level that cannot normally be reached by simply matting (roughening) the surface layer portion, for example, within a range of 60% to 90%. It is also possible to do.

  Incidentally, the light incident side surface of the lower polarizing plate 40 and the light incident side surface 50 b of the protective film 50 that forms the light incident surface of the liquid crystal display panel 15 are formed as optical element surfaces composed of the unit optical elements 60. On the other hand, the light exit side surface 50a of the protective film 50 is formed as a flat surface. Thereby, it becomes possible to laminate | stack and adhere | attach the protective film 50 and the polarizer 41 stably, preventing mixing of air etc.

  In the present specification, the term “flat” used for the surface 50 a of the protective film 50 facing the polarizer 41 is a level that can ensure stable lamination and adhesion between the protective film 50 and the polarizer 41. Refers to the flatness. For example, when the surface roughness of the surface 50a facing the polarizer 41 of the protective film 50 is measured as a ten-point average roughness Rz in accordance with JIS B0601 (1982), it may be 1.0 μm or less. It can be said that it is flat.

  Although the protective film 50 is internally added with the diffusing component 59b, the light-exiting side surface 50a of the protective film 50 is flat, so that the protective film 50 and the polarizer 41 are attached by so-called “water sticking”. Can be laminated and glued. Specifically, the protective film 50 and the polarizer 41 are overlapped with each other with an aqueous solution (or suspension) mixed with water or a suitable additive such as a surfactant interposed therebetween. To go. Thereby, the protective film 50 and the polarizer 41 can be laminated | stacked, preventing mixing of foreign materials, such as air. At this time, an adhesive (for example, glue) is mixed with water or an aqueous solution (or suspension), or an adhesive layer is provided in advance on at least one of the protective film 50 and the polarizer 41, The protective film 50 and the polarizer 41 may be positively bonded.

In addition, in order to accelerate | stimulate the removal of the water | moisture content from the protective film 50 and the polarizer 41 after "water sticking", the water vapor transmission rate of the protective film 50 is 10 g / m under the condition of temperature 40 degreeC and humidity 90% RH. It is preferably ² · 24 hours or more. However, if the moisture permeability is too high, warping or bending due to moisture absorption may occur. Therefore, the moisture permeability is preferably 400 g / m ² · 24 hr or less as measured at a temperature of 40 ° C. and a humidity of 90% RH. . In addition, the moisture permeability in this specification refers to the numerical value measured using the cup method based on JISZ0208.

  Here, with reference mainly to FIG. 6, an example of the manufacturing method of the protective film 50 which consists of the above structures is demonstrated. In the following description, the light diffusion layer 51a of the protective film 50 is formed as an extruded material extruded by extrusion processing.

  First, the extrusion apparatus 80 which can be used for manufacture of the light-diffusion layer 51a of the protective film 50 is demonstrated. As shown in FIG. 6, the extruding device 80 includes an extruding machine 82 including a die 82 a, a forming roll 84, a backup unit 86 disposed so as to face the forming roll 84, and downstream of the forming roll 84 and the backup unit 86. Guiding means 88 arranged on the side. The guiding means 88 is configured as a pair of guide rolls 88a. In addition, the extrusion device 80 includes a heating unit 83 that heats the molding roll 84 and a cooling unit 87 that cools the molding roll 84.

  The molding roll 84 has a cylindrical outer shape. The columnar molding roll 84 is rotatable about a rotation axis passing through the center of the column.

  Further, the molding roll 84 has a center portion 85a, a surface layer portion 85c, and a heat insulating portion (heat insulating layer) 85b provided between the center portion 85a and the surface layer portion 85c. The surface layer portion 85 c constitutes a molding surface 84 a of the molding roll 84. The heat insulating part 85b has higher heat insulating properties than the surface layer part 85c and the central part 85a. In addition, the level of heat insulation can be evaluated using heat conductivity, and it can be said that heat insulation is so high that the value of heat conductivity is small. As an example, the heat insulating portion 85 can be made of super engineering plastic, particularly polyether ether ketone or ceramics, and the surface layer portion 85c and the central portion 85a can be made of steel.

  The backup means 86 has two or more support rolls 86a and an edgeless belt member (belt) 86b spanned between the two or more support rolls 86a. In the illustrated example, the backup means 86 has two support rolls 86a. Each support roll 86a is formed in a columnar shape, and is rotatable around a rotation axis passing through the center of the column. The rotation axes of the support rolls 86a are parallel to each other, and are also parallel to the rotation axis of the forming roll 84. And the two or more support rolls 86a can drive the belt member 86b spanned over the said support roll 86a by rotating centering around a rotating shaft line.

  In the illustrated example, one of the two support rolls 86 a is configured as a nip roll 86 a 1 that is disposed to face the molding roll 84. The other of the two support rolls 86a is configured as an adjustment roll 86a2 that establishes a moving path of the belt member 86b with the nip roll 86a1.

  As shown in FIG. 6, the belt member 86 b between the nip roll 86 a 1 and the adjustment roll 86 a 2 is deformed corresponding to the outer contour of the molding roll 84 by pressing from the molding roll 84. For this reason, as will be described later, the film material 90 passing between the belt member 86b and the molding roll 84 passes over the nip section NZ of a certain length L along the movement path, and the belt member 86b and the molding roll 84 Will continue to be pressurized. In the configuration shown in FIG. 6, for example, the length L of the nip section NZ can be adjusted as appropriate by adjusting the position of the support roll 86a, particularly the adjustment roll 86a2.

  The forming roll 84, the nip roll 86a1, the adjustment roll 86a2, and the belt member 86b are configured using various materials. For example, as the forming roll 84, the nip roll 86a1, and the adjustment roll 86a2, a metal roll, a roll whose center portion is made of metal and whose surface layer portion is made of an elastic body (for example, rubber) can be used. Further, as the belt member 86b, a durable metal edge belt, for example, a belt-like member made of a metal alloy such as a chromium alloy or a nickel alloy can be used.

  In addition, it is not restricted to the above example, The backup means 86 may be comprised from the mere metal roll or the rubber roll.

  As shown in FIG. 6, the heating unit 83 has a molding roll at a position immediately before the backup unit 86 of the molding roll 84 that faces the backup unit 86, that is, at a position just before contacting the extruded material 90 of the molding roll 84. 84 can be heated from the molding surface 84a. As the heating means 83, a far-infrared heater 83a can be used as shown in FIG.

  On the other hand, the cooling means 87 is disposed to face the molding roll 84 at a position between the backup means 86 and the adjusting means 88 along the movement path of the extruded material 90. The cooling means 87 can contact the surface layer portion 85c of the molding roll 84 via the extrusion material 90, and can cool the molding roll 84 from the molding surface 84a. As the cooling means 87, a cooling roll 87a in which a circulation path for a refrigerant (for example, cooling water) is formed can be used.

  As described above, the molding roll 84 is adjacent to the surface layer portion 85c that forms the molding surface 84a, and is provided with a heat insulating portion 85b having excellent heat insulating properties. Therefore, it is mainly the surface layer portion 85 c of the molding roll 84 that is heated from the heating means 83, and the surface layer portion 85 c of the molding roll 84 is mainly deprived of heat by the cooling means 87. For this reason, by reducing the thickness of the surface layer portion 85c and reducing the heat capacity of the surface layer portion 85c, the temperature of the surface layer portion 85c of the molding roll 84 can be quickly and greatly increased using the heating means 83 and the cooling means 87. It becomes possible to change to. Specifically, the surface layer portion 85c of the molding roll 84 cooled by the cooling means 87 can be heated in a short time by heating from the heating means 83, and conversely, the molding roll heated by the heating means 83. The surface layer portion 85c of 84 can be cooled in a short time by cooling by the cooling means 87.

  Next, a method for manufacturing the above-described protective film 50 using such an extrusion device 80 will be described. Here, the light diffusing layer 51a of the protective film 50 is produced by being extruded and uniaxially stretched, and then, a plurality of unit optical elements 60 are formed on the light diffusing layer 51a to form the protective film 50. An example of manufacturing will be described.

  First, a material that will form the light diffusion layer 51 a is put into the extruder 82. The material that forms the light diffusion layer 51a includes a resin material that forms the base portion 59a, that is, a thermoplastic resin (in this embodiment, a pellet-shaped thermoplastic resin material made of a polycarbonate resin), and , And fine particles 58a constituting the diffusing component 59b (in this embodiment, spherical particles of isotropic refractive index polycarbonate). In the present embodiment, as the fine particles 58a, those having a refractive index isotropic whose refractive index is 1.57 in all directions are used.

  The thermoplastic resin charged in the extruder 82 is heated in the extruder 82 to the glass transition temperature or higher. The heated and softened resin material is extruded by the extruder 82 as a single-layer extrusion material.

  As an example, when a polycarbonate resin having a glass transition temperature around 140 ° C. is used as the thermoplastic resin forming the base portion 59a of the light diffusion layer 51a, the temperature of the thermoplastic resin immediately after passing through the die 82a is You may make it heat a thermoplastic resin in the extruder 82 so that it may become about 300 degreeC. In this case, the content of the fine particles 58a can be more than 0% by weight and 40% by weight or less.

  In this way, the film material 90 having the thermoplastic resin and the fine particles 58a dispersed in the thermoplastic resin is formed as an extruded material. At this time, in the die 82a of the extruder 82, the thickness of the film material 90 can be controlled to a desired thickness.

  The film material 90 extruded from the extruder 82 advances between the forming roll 84 and the backup means 86. At this time, one surface of the film material 90 comes into contact with the backup means 86, and the other surface comes into contact with the molding roll 84. Then, the film material 90 is pressed from the other surface by the molding roll 84 while being supported from the one surface of the film material 90 by the edgeless belt 86b of the backup means 86. The pressing of the film material 90 by the edgeless belt 86b and the molding roll 84 of the backup means 86 is continued while the film material 90 proceeds through the section NZ having a predetermined length.

  During this time, the fine particles 58a are pushed into the film material 90, so that both surfaces of the film material 90 can be surely flattened.

  The edgeless belt 86b has a much smaller heat capacity than the molding roll 84, and is not heated by a heater or the like. Therefore, even if the edgeless belt 86 b absorbs heat from the film material 90, it performs sufficient heat dissipation while not in contact with the film material 90. For this reason, when the edgeless belt 86b comes into contact with the film material 90 again, the temperature of the edgeless belt 86b is sufficiently lowered, and the edgeless belt 86b promotes cooling of the film material 90. As a result, when the film material 90 moves away from the edgeless belt 86b of the backup means 86, the belt side portion of the film material 90 that has been in contact with the edgeless belt 86b of the film material 90 is sufficiently cooled. That is, the film material 90 can be sufficiently cooled by the edgeless belt 86b so that the thermoplastic resin contained in the belt side portion of the film material 90 reaches a temperature below its melting point or melting temperature.

  In addition, when the temperature of the belt side portion of the film material 90 is lowered to the melting point or lower than the melting temperature of the resin material that forms the base portion 59a of the light diffusion layer 51a, The thermoplastic resin material has a certain degree of deformation resistance. For this reason, it becomes difficult to produce the thermal deformation resulting from the difference of the thermal expansion coefficient of the resin material which makes the base material part 59a, and the thermal expansion coefficient of the fine particle 58a. That is, the portion of the resin material that forms the base portion 59a is retreated, and the contour of the fine particles 58a is suppressed from rising, and the surface of the film material 90 that is in contact with the edgeless belt 86b is flat. Can be maintained.

  On the other hand, the temperature of the film material 90 immediately after being extruded from the extruder 82 has risen to about 300 ° C. Immediately before the film roll 90 comes into contact with the film material 90, the molding roll 84 is heated from the side of the molding surface 84 a by the heating means 83. The surface layer portion 85c including the molding surface 84a is partitioned from the central portion 85a by the heat insulating portion 85b, and the temperature thereof can be increased rapidly and significantly. At this time, the temperature of the molding surface 84a is equal to or higher than the glass transition temperature of the resin material to be molded by the molding roll 84, for example, about 160 ° C. when the molded resin material is polycarbonate. Until heated. Thus, the film material 90 immediately after being extruded is pressed by the heated molding surface 84a of the molding roll 84 and the edgeless belt 86b of the backup means 86.

  The film material 90 is pressed between the edgeless belt 86b of the backup unit 86 and the molding roll 84 while traveling through the section NZ having a predetermined length. During this time, as described above, the film material 90 is deprived of heat by the edgeless belt 86 b of the backup means 86, and the film material 90 is also deprived of heat from the forming roll 84. However, as described above, the heat of the film material 90 is rapidly taken away from the edgeless belt 86 b side, but the molding roll 84 is heated immediately before contacting the film material 90. Therefore, the molding roll 84 is molded on the molding surface 84a of the molding roll 84 for a predetermined time in a state where the roll side portion of the film material 90 is maintained at a high temperature, preferably a temperature equal to or higher than the glass transition temperature. It will be pressed by the surface 84a. As a result, the surface of the film material 90 on the molding roll 84 side is surely flat.

  As shown in FIG. 6, the film material 90 released from the pressure between the backup means 86 and the molding roll 84 is supported by the backup means 86 and the guiding means 88, and thereafter the molding roll 84. It is pressed toward the molding surface 84a. The film material 90 disposed on the molding surface 84 a of the molding roll 84 then passes between the molding roll 84 and the cooling roll 87 a that forms the cooling means 87. At this time, the film material 90 is cooled by the cooling means 87 while being pressed toward the molding surface 84a. Therefore, during this cooling, the film material 90 is pressed against the molding surface 84a, so that deformation is restricted. Thereby, it can prevent effectively that the surface by the side of the shaping | molding roll 84 of the film material 90 becomes non-flat by heat contraction.

  At the same time, the surface layer portion 85c including the molding surface 84a of the molding roll 84 is also cooled by the cooling roll 87a through the film material 90. Thus, when the film material 90 is moved to a temperature lower than the glass transition temperature of the resin material forming the film material 90 together with the surface layer portion 85c of the molding roll 84, for example, when the resin material to be cooled is polycarbonate. It can be stably cooled to about 130 ° C. Thus, since the temperature of the surface layer portion 85c of the molding roll 84 is cooled to below the glass transition temperature of the resin material forming the film material 90, the temperature of the film material 90 is again changed to the glass transition point. Without raising the temperature to exceed the temperature, it is possible to maintain a highly accurate flat surface as it is.

  The film material 90 separated from the molding roll 84 is then cooled by the guiding means 88 and guided while being moderately warped and corrected for warping and bending. As described above, a film material (extruded material) 90 obtained by extruding a thermoplastic resin material together with the fine particles 58a is obtained. The flat light exit side surface 50a of the light diffusion layer 51a of the protective film 50 is formed by the surface of the film material 90 that has been in contact with the backup means 86, and is on the flat light incident side of the light diffusion layer 51a of the protective film 50. The surface is formed by the surface that was in contact with the forming roll 84 of the film material 90.

  The film material 90 extruded by the extrusion device 80 is uniaxially stretched. In the case of the form shown in FIG. 4 or FIG. 5, the interface between the fine particles 58a and the resin material forming the base portion 59a is peeled off, and the spherical fine particles 58a have a spheroid band shape circumscribing them. A gap 58b is formed. As a result, the diffusion component 59b including the fine particles 58a and the voids 58b and having the longitudinal direction ld is formed, and the light diffusion layer 51a of the protective film 50 stretched uniaxially is obtained. The film material 90 has a refractive index of 1.61 with respect to light whose electric field vibrates in the slow axis direction (the x direction in FIG. 5 and corresponds to the stretching direction) of the base material portion 59a. The material portion 59a is stretched so that the refractive index with respect to light whose electric field vibrates is 1.57 in the fast axis direction (the y direction in FIG. 5 and perpendicular to the stretching direction).

  Thereafter, a resin layer 51b including a plurality of unit optical elements 60 is produced by applying a resin on a light incident side surface of the light diffusion layer 51a and molding the resin into a desired shape. In this way, the protective film 50 in the present embodiment is obtained.

  Next, the operation of the display device 10 resulting from the protective film 50 will be described mainly with reference to FIG.

  In FIG. 3, the light emitted from the light emitter 26 of the light source 25 travels to the viewer side directly or after being reflected by the reflecting plate 21 and enters the liquid crystal display panel 15. A lower polarizing plate 40 is provided on the most incident light side of the liquid crystal display panel 15. The protective film 50 of the lower polarizing plate 40 forms the most incident light side surface of the liquid crystal display panel 15.

  As described above, the protective film 50 has a light collecting function that changes the traveling direction of the light so that the angle formed by the traveling direction of the light with respect to the front direction nd is reduced as a whole, and light of a predetermined polarization component. A polarization separation function that transmits light and an anisotropic light diffusion function that diffuses specific polarized light. Among these, the light condensing function is expressed by the unit optical element 60 of the protective film 50, and the polarization separation function and the anisotropic light diffusion function are mainly expressed by the light diffusion layer 51 a of the protective film 50. The unit optical element 60 forms the light incident side surface of the protective film 50, and the light diffusion layer 51 a is provided on the light outgoing side of the protective film 50. For this reason, the light incident on the protective film 50 is first subjected to a light condensing function, and then to a polarization separation function and an anisotropic light diffusion function.

  As is well shown in FIG. 3, the basic principle of the light collecting function by the unit optical element 60 is that the light L31 and L32 incident from one light incident side surface 60b1 of the unit optical element 60 is changed to the other light incident side surface 60b2. In this case, the angle at which the traveling direction of the light is formed with respect to the front direction nd is reduced. That is, the light condensing function by the unit optical element 60 is mainly exerted on the light component parallel to the arrangement direction of the unit optical elements 60. Then, by appropriately designing the cross-sectional shape of the unit optical element 60, as shown in FIG. 3, the light condensing function of the unit optical element 60 of the protective film 50 is two light emitters adjacent in the arrangement direction. 26, which is a region including a position facing the intermediate point 26 and has a tendency that the brightness tends to decrease.

  In other words, the unit optical element 60 not only collects light components along the arrangement direction but also functions to alleviate unevenness in brightness along the arrangement direction. As described above, since the unit optical elements 60 mainly exhibit an optical function with respect to light components parallel to the arrangement direction, the arrangement directions of the unit optical elements 60 are as shown in the examples shown in FIGS. Is parallel to the arrangement direction of the light emitters 26, the brightness variation along the arrangement direction of the light emitters 26 can be effectively uniformed and made inconspicuous. Therefore, in the example shown in FIG. 1, the first arrangement direction of the light emitters 26 that are two-dimensionally arranged is parallel to the arrangement direction of the unit optical elements 60. Unevenness of brightness can be eliminated, and the in-plane distribution of luminance can be effectively made uniform.

  As described above, the unit optical element 60 of the protective film 50 is useful for improving the luminance in the front direction, and uneven brightness (in-plane variation in luminance) due to the configuration (arrangement) of the light emitter 26 of the light source 25. It also helps to ease. In addition, in the present embodiment, since the diffusion component 59b is not dispersed in the unit optical element 60, the surface (prism surface) of the unit optical element 60 that functions as the incident surface 60b1 and the total reflection surface 60b2 is diffused. It can be formed with high accuracy as a flat surface without unevenness due to the component 59b. Thereby, the unit optical element 60 of the protective film 50 can exhibit the expected desired optical function.

  The degree of such a light condensing function in the protective film 50 is determined by the arrangement pitch pa1 of the two adjacent light emitters 26 and the light emitting body 26 and the protective film 28 along the normal direction to the film surface of the protective film 50. By appropriately setting the separation distance la1, the shape of the unit optical element 60, the refractive index of the unit optical element 60, etc., it can be adjusted within a very wide range.

  The light incident on the protective film 50 through the unit optical element 60 then travels in the main body portion 55 from the resin layer 51b to the light diffusion layer 51a having a polarization separation function and an anisotropic light diffusion function. The light diffusion layer 51a includes a base material portion 59a and a diffusion component 59b having a longitudinal direction ld dispersed in the base material portion 59a, and the refractive index anisotropy of the base material portion 59a. The resulting polarization separation function and the anisotropic light diffusion function due to the internally added diffusion component 59b are exhibited.

  Here, the base material portion 59a of the light diffusion layer 51a of the protective film 50 has refractive index anisotropy, and the refractive index in the fast axis direction (y direction in FIG. 5) is in the slow axis direction (FIG. 5). Less than the refractive index in the x direction). Thus, the difference between the refractive index of the base material portion 59a in the fast axis direction and the refractive index of the fine particles 58a of the diffusion component 59b is different from the refractive index of the base material portion 59a in the slow axis direction and the gap portion 58b. The difference from the refractive index is smaller. As for the fast axis (y) direction, as shown in FIG. 5, among the diffusion components 59b (fine particles 58a and voids 58b), the fine particles 58a and the base material portion 59a are in direct contact, and the base material portion. The difference in refractive index between 59a and diffusing component 59b is relatively small (in the case of the present embodiment, 1.57-1.57 = 0.00). On the other hand, in the slow axis (x) direction, as shown in FIG. 5, the base material portion 59a is in contact with the air gap portion 58b made of air having a refractive index of 1.00 in the diffusion component 59b. And the diffusion component 59b have a relatively large difference in refractive index (in the case of this embodiment, 1.61-1.00 = 0.61). For this reason, among the light incident on the interface between the base material portion 59a and the diffusing component 59b, light having a polarization component parallel to the fast axis of the base material portion 59a (light vibrating in the y direction) has a transmittance. High and low reflectivity. Further, since the refracting action by the diffusing component 59b is not received, the transmitted light becomes non-diffused light. On the other hand, light having a polarization component parallel to the slow axis (light oscillating in the x direction) has low transmittance and high reflectance. Further, the transmitted light is emitted as diffused light by the refracting action of the diffusing component 59b. That is, the incident non-polarized light by the light diffusing layer 51a of the protective film 50 is a relatively low-diffused transmitted light containing a relatively large amount of polarized light components parallel to the fast axis direction of the base material portion 59a, and The base material portion 59a is separated into highly diffuse reflected light that contains a relatively large amount of polarized light components parallel to the slow axis direction, and exhibits a polarization separation function. Further, since the fast axis of the base material portion 59a is set parallel to the transmission axis of the polarizer 41, the ratio of light that can be transmitted through the polarizer 41 and used for image display can be increased. . Further, the light reflected at the interface between the base material portion 59a and the gap portion 58b is returned to the light source 25 side, and the polarization state is canceled by the subsequent reflection or the like (the phase advance that can be transmitted through the light diffusion layer 51a). A process of transmitting a part of the light to the light diffusing layer 51a of the protective film 50 and allowing the light to be transmitted through a part of the light diffusion layer 51a. Can be improved.

  When the diffusion component 59b having the longitudinal direction ld is used, as described above, in addition to the anisotropic diffusion function whose diffusivity depends on the polarization direction, the diffusion angle in a direction parallel to the longitudinal direction is larger than the diffusion angle. , The diffusion angle in the direction orthogonal to the longitudinal direction becomes wider (diffusibility becomes stronger), and the surface of the diffusion angle (even in terms of the angle dependence of the transmitted or reflected light intensity) is strong anisotropic light. Presents a diffusion function. As for the degree of anisotropy of the diffusion angle, the diffusion angle in the direction perpendicular to the longitudinal direction ld is 1.1 to 5 times the transmission light of the protective film 50 when the diffusion angle in the longitudinal direction ld is 1. Designed to be Here, the diffusion angle is evaluated by a half-value angle (an angle range having a luminance that is half or more of the maximum luminance).

  The anisotropic light diffusing function in the light diffusing layer 51a due to such internally added diffusing component 59b is achieved by, for example, forming the surface into a matte surface by molding or providing a granular material on the surface layer portion to form a matte surface. Compared with the light diffusing function resulting from the conversion, the degree (diffusion intensity) and quality (diffusion uniformity) are remarkably excellent.

  Specifically, when the surface is merely matted, light that passes through like the light beam L91 indicated by a two-dot chain line in FIG. ) Will occur. On the other hand, according to the internally added diffusion component 59b, the diffusion component 59b is dispersed not only in the plane direction but also in the thickness direction. For this reason, the lights L92 and L93 incident on the light diffusion layer 51a collide with the diffusion component 59b at least once and change the traveling direction thereof with a high probability. Further, as described above, the resin material forming the base portion 59a, the thickness of the base portion 59a, the configuration (shape, size (particle size), refractive index, etc.) of the diffusing component 59b, the concentration of the diffusing component 59b, etc. By appropriately setting, the degree of the anisotropic light diffusion function of the light diffusion layer 51a can be adjusted within a very wide range.

  As described above, the light from the surface light source device 20 can be diffused to some extent by the light diffusion layer 51 a of the protective film 50. This diffusion phenomenon occurs for both the transmitted light and the reflected light with respect to the polarization component whose electric field oscillates in the slow axis direction of the base material portion 59a. Thereby, the angle distribution of the brightness after being condensed by the unit optical element 60 of the protective film 50 can be changed smoothly. Moreover, the surface of the brightness | luminance resulting from the arrangement | sequence of the light-emitting body 26 along the 1st arrangement direction d1 and the 2nd arrangement direction d2 by adjusting the grade of the light-diffusion function in the light-diffusion layer 51a of the protective film 50 suitably. It is also possible to effectively uniform the internal distribution and more reliably prevent the image (light image) of the light emitter 26 from being visually recognized.

  The light diffused by the light diffusion layer 51 a of the protective film 50 then travels toward the polarizer 41, the liquid crystal cell 11, and the upper polarizing plate 12 of the lower polarizing plate 40 disposed on the light output side of the protective film 50. At this time, the liquid crystal cell 11 selectively transmits light for each pixel, so that an observer of the display device 10 can observe an image.

  According to the present embodiment as described above, in the optical module 20 incorporated in the display device 10, the protective film 50 joined to the polarizer 41 to form the polarizing plate (lower polarizing plate) 40 is a light It has an excellent light control function that can change the traveling direction of the light. Specifically, the protective film 50 projects toward the light-emitting body 26 side with respect to the polarization separation function, the anisotropic light diffusion function, and the light emitting body 26 due to the refractive index anisotropy of the base material portion 59a. It is possible to exhibit an excellent light condensing function due to the plurality of unit optical elements 60 forming the following. Due to the excellent light control function by the protective film 50, the diffusion plate A, the lower diffusion sheet B, the light collecting sheet C and the upper diffusion sheet incorporated in the surface light source device of the conventional display device 1 shown in FIG. It becomes possible to delete optical sheets such as D.

  Thereby, the number of members (optical sheets) incorporated in the display device can be greatly reduced, and the manufacturing cost and weight of the display device can be greatly reduced directly. Further, it is possible to omit a complicated operation such as positioning of optical sheets necessary for assembling the display device or the surface light source device, and the manufacturing cost of the display device can also be reduced in this respect. Further, by omitting a member (optical sheet) incorporated in the display device, the display device can be thinned.

  In addition, the optical sheets incorporated in the conventional display device are members for correcting the traveling direction of light, but on the other hand, a part of incident light is absorbed. In addition, in the conventional display device, a lot of light is reflected by any one of the optical sheets, and enters the display panel after returning its traveling direction one or more times. As a result, most of the light emitted from the light emitter 26 serving as the light source 25 is absorbed by any one of the optical sheets and cannot be used for displaying an image. On the other hand, according to the present embodiment described above, the light emitter 26 constituting the light source 25 faces the protective film 50 of the polarizing plate 40, that is, faces without any member interposed therebetween. Therefore, the light emitted from the light emitter 26 can be directly incident on the polarizing plate 40 of the liquid crystal display panel 15, and even if it is reflected, the liquid crystal display panel can be reflected by a single reflection on the reflection plate 21. It can reenter the 15 polarizing plates 40. For this reason, the utilization efficiency of the light emitted by the light emitter 26 can be significantly increased. As a result, for example, it is possible to significantly widen the viewing angle while maintaining the luminance in the front direction without increasing the output of the light source 25 as compared with the conventional display device.

  Furthermore, according to the present embodiment, since the optical sheet is not disposed between the light emitter 26 forming the light source 25 and the protective film 50 of the polarizing plate 40, the optical sheet is deformed such as bending, bending, warping, and the like. It is possible to avoid problems such as degradation of display image quality caused by it. In the conventional display device, as shown in FIG. 16, the thickness of the member (diffusion plate A) facing the light emitter is not changed by heat generated from the light emitter. It was thick so that the heat transfer toward the member (diffusion sheet or condensing sheet) located on the light exit side could be blocked. Thus, when the thickness of the diffusing plate A increases, the material cost of the diffusing plate A increases, and as a result, the manufacturing cost of the display device increases. Further, when the diffusion plate A having a certain thickness is to be incorporated into the surface light source device, it is necessary to install a corresponding support mechanism. On the other hand, according to the present embodiment, the protective film 50 facing the light emitter 26 is laminated on the liquid crystal display panel 15 as a part of the polarizing plate 40. That is, since the protective film 50 is directly supported by the liquid crystal display panel 15, a special support mechanism for supporting the protective film 50 is not necessary, and deformation of the protective film 50 is restricted by the liquid crystal display panel 15. . Therefore, the thickness of the protective film 50 can be determined from the viewpoint of the optical action expected for the protective film 50 and the protective action of the polarizer, and as a result, the manufacturing cost of the display device 10 can be reduced.

  In the conventional display device 1 shown in FIG. 16, the configuration of the light source 25, the reflecting plate 21, the liquid crystal cell 11, and the upper polarizing plate 12 can be configured in the same manner as in the above-described embodiment.

  Moreover, according to this Embodiment, the base material part 59a of the light-diffusion layer 51a of the protective film 50 has refractive index anisotropy. As a result, a polarization component parallel to the fast axis of the base material portion 59a is generated at the interface between the base material portion 59a and the fine particles 58a of the diffusing component 59b and at the interface between the base material portion 59a and the gap 58b of the diffusing component 59b. The light having the polarization component parallel to the slow axis is transmitted and the polarization separation function can be exhibited. In particular, when the fast axis of the base material portion 59a is set parallel to the transmission axis of the polarizer 41, non-polarized light (highly characteristic light) incident from the light source 25 is transmitted through the polarizer 41. Thus, it is possible to obtain light with an increased ratio of polarization components that can be used for image formation, and it is possible to increase the ratio of light that can be used as the entire polarizing plate 40. In addition, the light reflected at the interface between the base material portion 59a and the gap portion 58b is returned to the light source side, and is then incident again on the light diffusion layer 51a of the protective film 50 by canceling the polarization state by subsequent reflection or the like. And the utilization efficiency of the light emitted from the light emitter 26 can be improved.

  Further, according to the present embodiment, the diffusion component 59b of the light diffusion layer 51a of the protective film 50 has the longitudinal direction ld, and the average direction of the longitudinal direction ld of each diffusion component 59b is oriented in the predetermined direction od. ing. Thereby, the protective film 50 exhibits an anisotropic light diffusion function such that the diffusion angle in the direction orthogonal to the predetermined direction od is wider than the diffusion angle in the od direction. In particular, in the embodiment shown in FIG. 4, the longitudinal direction ld of the diffusing component 59 b is oriented in a direction parallel to the longitudinal direction of the unit optical element 60. The direction in which the optical function is mainly exhibited coincides with the direction in which the anisotropic light diffusion function is mainly exhibited. For this reason, it is possible to selectively smooth the angular distribution of the luminance in the plane where the light collecting action is mainly exerted from the unit optical element 60, and it becomes unnecessary to diffuse the light incident on the protective film 50 more than necessary. Effective use of light can be achieved.

  Furthermore, according to the present embodiment, the light diffusion layer 51a of the protective film 50 having the polarization separation function and the anisotropic light diffusion function as described above extrudes the resin material in which the fine particles 58a are diffused, and is uniaxially stretched. By doing so, refractive index anisotropy can be imparted to the base material portion 59a made of the resin material, and a diffusion component 59b can be formed in the base material portion 59a. For this reason, the light-diffusion layer 51a of the protective film 50 which has a polarization separation function and an anisotropic light-diffusion function can be manufactured easily.

  Various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings as appropriate. In the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above-described embodiment are used, and redundant descriptions are omitted.

  In embodiment mentioned above, although the light-diffusion layer 51a of the protective film 50 showed the example which extruded the resin material in which the fine particle 58a was disperse | distributed and was uniaxially stretched, it is not restricted to this. You may uniaxially stretch using the protective film containing the fine particle 58a manufactured by other manufacturing methods, such as cast molding, calendar molding, and injection molding. Further, as long as the refractive index anisotropy can be imparted to the base material portion 59a of the light diffusion layer 51a, the light diffusion layer 51a may be manufactured using other methods without being limited to uniaxial stretching.

  In the above-described embodiment, as an example in which the average orientation direction of the longitudinal direction ld of the diffusion component 59b having the longitudinal direction ld is oriented in the predetermined direction od, the average orientation direction od of the diffusion component 59b is arranged in parallel. The example which is parallel to the longitudinal direction of the linear unit optical element 60 was shown. However, the average orientation direction od of the diffusion component 59b may be parallel to the arrangement direction of the unit optical elements 60, for example. When oriented in this way, the transmitted light of the protective film 50 exhibits a wide diffusion angle in the longitudinal direction of the unit optical elements 60, while condensing (narrow diffusion) in the arrangement direction of the unit optical elements 60. Corner). In short, what is necessary is just to have the orientation to arbitrary directions, in order to achieve a desired objective.

  Further, in the above-described embodiment, an example has been shown in which the light emitters 26 forming the light source 25 of the optical module 20 are two-dimensionally arrayed point light emitters, typically light emitting diodes. However, the light emitter 26 is not limited to the above-described example, and various known light emitters, for example, a cold cathode tube, an EL (electroluminescent material) that emits light in a planar shape, or the like can also be used. FIG. 7 discloses an example in which a linear cold cathode tube is used as the light emitter 26. In the example shown in FIG. 7, the linear cold-cathode tubes forming the light emitter 26 are arranged in a predetermined arrangement direction so as to be parallel to each other. The arrangement direction of the linear cold cathode tubes is parallel to the arrangement direction of the unit optical elements 60 of the protective film 50. According to this aspect, as already described in the above-described embodiment, the in-plane variation in luminance caused by the arrangement of the cold cathode tubes 26 is alleviated by the unit optical element 60, and an image of the cold cathode tube 26 ( Light image) can be made difficult to see.

  Furthermore, in embodiment mentioned above, although the cross-sectional shape in the main cut surface of the unit optical element 60 of the protective film 50 showed the example which consists of a triangular shape, it is not restricted to this, The unit optical element 60 of the protective film 50 of the unit optical element 60 is shown. The cross-sectional shape at the main cutting plane can be designed in various shapes. For example, the top of the triangular shape that forms the cross-sectional shape of the unit optical element 60 on the main cut surface of the protective film 50 may be chamfered. In addition, as shown by a two-dot chain line in FIG. 3, the two sides extending from the above-described triangular main body 55 on the main cut surface of the protective film 50 are deformed so as to be curved outward. May be.

  Furthermore, as shown in FIG. 8, the unit optical element 60 may have a curved outer contour on the main cut surface of the protective film 50. That is, the light incident surface of the unit optical element 60 may be configured as a curved surface. As an example of a specific shape, the unit optical element 60 has a shape corresponding to a part of an ellipse (a semi-ellipse as an example) or a part of a circle (a semi-circle as an example) on the main cut surface of the protective film 50. You may do it. Furthermore, as shown in FIG. 9, on the main cutting surface of the protective film 50, the unit optical element 60 may have a shape obtained by removing the top of the triangular shape on the main cutting surface. As an example of a specific shape, the unit optical element 60 may have an isosceles trapezoidal shape as shown in FIG. 9 on the main cut surface of the protective film 50, or alternatively, the isosceles trapezoidal shape. You may make it have the shape formed by changing an upper base into a curve. Also, as shown in FIG. 2, when the top of each unit optical element 60 protrudes and extends in the longitudinal direction to form a ridge line portion, the height of the ridge line portion is constant over the entire length direction. 15, when placed in contact with the surface of the light guide plate 23, the entire area of the ridge line portion is in contact with the light guide plate 23 with a wide area (or length). Out (also called light infiltration), defects such as white spot unevenness are likely to occur. In order to reduce this, as disclosed in Japanese Patent No. 3119471, Japanese Patent No. 4168179, Japanese Patent Application Laid-Open No. 2005-234537, etc., the height of the ridge line portion is randomly or regularly set. You may modulate.

  Furthermore, in the above-described embodiment, an example in which the unit optical elements 60 are one-dimensionally arranged on the main body portion 55, that is, an example in which the linear unit optical elements 60 are arranged in parallel on the main body portion 55. However, the present invention is not limited to this. The unit optical elements 60 may be two-dimensionally arranged on the main body 55 so as to constitute a so-called fly-eye lens (or microlens). In this example, the unit optical elements 60 may be arranged in a regular arrangement on the main body portion 55 or may be arranged in an irregular arrangement. When the point-shaped unit optical elements 60 are two-dimensionally arranged in a regular arrangement on the main body 55, the first arrangement direction of the unit optical elements 60 is the first arrangement direction d1 of the light emitters 26. (See FIG. 1), and the second arrangement direction of the unit optical elements 60 may be parallel to the second arrangement direction d2 of the light emitters 26 (see FIG. 1). Further, the shape of the point-shaped unit optical element 60 constituting the fly-eye lens (or microlens) includes a part of a sphere (for example, a hemisphere), a part of a spheroid (for example, a half-spheroid), a cone, Examples include a pyramid such as a polygonal pyramid such as a quadrangular pyramid, a frustum such as a truncated cone and a polygonal frustum such as a quadrangular pyramid, and the like.

  Furthermore, in embodiment mentioned above, although the protective film 50 showed the example which has a condensing function, it is not restricted to this. For example, if the light from the light emitter 26 is sufficiently condensed, it is not necessary to provide the protective film 50 with a condensing function. That is, it is not necessary to provide the unit optical element 60 on the protective film 50. Moreover, you may provide members, such as the condensing sheet C (refer FIG. 16) which has a condensing function, between the protective film 50 and the light source 25, without providing the unit optical element 60 in the protective film 50. FIG.

  Here, the example in which the unit optical element 60 is not provided in the protective film 50 is shown by FIGS. That is, in FIGS. 10-12, the protective film 50 consists only of the light-diffusion layer 51a containing the diffusion component 59b which has the longitudinal direction ld, and comes to exhibit an anisotropic light-diffusion function effectively. Among these, in the example shown by FIG. 10, both the light emission side surface 50a and the light-incidence side surface 50b of the protective film 50 are comprised as a flat surface. The protective film 50 shown in FIG. 10 can be manufactured by the extrusion process described above using a molding roll 84 having a molding surface 84a configured as a flat surface.

  In the example shown in FIG. 11, the light exit side surface 50a of the protective film 50 is configured as a flat surface, and the light incident side surface 50b (also the light incident side surface 55b of the main body) is formed as an uneven surface. Has been. The unevenness provided on the light incident side surface 50b is caused by the diffusion component 59b having the longitudinal direction ld dispersed in the base material portion 59a. More specifically, the diffusion component 59b is exposed or the diffusion component. The outline 59b is raised. The protective film 50 shown in FIG. 11 can be manufactured by the extrusion process described above using a molding roll 84 having a molding surface 84a configured as a flat surface. However, while maintaining the cooling from the surface of the film material 90 extruded from the extruder 82 on the side in contact with the backup means 86 to a certain level, the surface on the side in contact with the forming roll 84 is maintained. Therefore, after the release from the molding roll 84, the film material 90 is cooled from the side in contact with the molding roll 84. In this case, the resin material forming the base material portion 59a is thermally contracted by cooling after being released from the molding roll 84, and thereby, the diffusion component 59b can be lifted from the base material portion 59a.

  In the example shown in FIG. 12, the light exit side surface 50a of the protective film 50 is configured as a flat surface, and the light incident side surface 50b of the protective film 50 is formed as an uneven surface. The unevenness provided on the light incident side surface 50b is formed by shaping. In the manufacturing method of the protective film described above, if the molding roll 84 having a concavo-convex pattern formed on the outer peripheral surface is used, the concavo-convex pattern of the molding roll 84 is transferred to the surface 90b of the extruded material 90 on the side contacting the molding roll 84 Thereby, unevenness | corrugation can be formed in the surface 90b (namely, light-incidence side surface 50b of the protective film 50) of the side which contacts the shaping | molding roll 84 of the extrusion material 90. FIG. In addition, when unevenness is formed on the light incident side surface 50b of the protective film 50 by molding, the unevenness due to the presence of the diffusing component 59b may not be formed on the light incident side surface 50b of the protective film 50 (FIG. 10), or unevenness due to the presence of the diffusion component 59b may be formed in addition to the unevenness due to shaping (example shown in FIG. 11).

  Furthermore, in embodiment mentioned above, although the protective film 50 showed the example joined to the polarizer 41 by water sticking, it is not restricted to this. For example, as shown in FIG. 13, an adhesive layer 49 containing an adhesive 49 a and a diffusion component 49 b dispersed in the adhesive 49 a is arranged between the protective film 50 and the polarizer 41. It may be. According to the embodiment shown in FIG. 13, the degree of the light diffusing function by the adhesive layer 49 can be appropriately adjusted independently of the degree of the anisotropic light diffusing function of the protective film 50. Thereby, the degree of the anisotropic light diffusion function that the lower polarizing plate 40 can exhibit can be designed more freely. The diffusing component 49b contained in the adhesive layer 49 may be composed of a granular material having a refractive index different from that of the adhesive 49a, or a granular material having its own reflectivity. The particulate material forming the diffusion component 49b may be a metal compound, a porous material containing a gas, or may be a simple bubble. Further, the shape of the diffusion component 49b made of a granular material is not particularly limited. Therefore, the diffusion component 49b may be, for example, spherical (particulate), unlike the diffusion component 59b having the longitudinal direction ld of the protective film 50, or may be, for example, a spheroid or line so as to have the longitudinal direction ld. It is good also as various shapes, such as a shape. Further, the degree of the light diffusion function by the adhesive layer 49 can be appropriately adjusted by the same method as the degree of the light diffusion function in the protective film 50.

  Thus, the light diffusing function of the adhesive layer 49 may be isotropic or anisotropic. When the adhesive layer 49 has an anisotropic light diffusing function, the direction in which the light diffusing function is exerted strongly by the adhesive layer 49 is the arrangement direction of the unit optical elements 60 (as in the embodiment shown in FIG. It may be parallel to the direction in which the light condensing function is exerted strongly, or may be parallel to the longitudinal direction of the unit optical element 60 (the direction in which the light condensing function is not exerted strongly).

  Furthermore, in embodiment mentioned above, although the lower polarizing plate 40 showed the example which consists only of the protective film 50 joined to the polarizer 41 and the polarizer 41 from the light-incidence side, it is not restricted to this, Furthermore, a protective film made of, for example, a TAC film may be provided on the light output side of the polarizer 41. In addition, a phase difference plate for compensating for the phase difference of light may be provided between the lower polarizing plate 40 and the liquid crystal cell 11, but in this case, the protective film on the light output side of the lower polarizing plate 40, You may make it also serve as the protective film of the light-incidence side of a phase difference plate. Further, as shown in FIG. 14, the lower polarizing plate 40 may further include another member positioned on the incident side with respect to the polarizer 41.

  In the example shown in FIG. 14, the intermediate film 48 between the protective film 50 and the polarizer 41 has a function of transmitting a specific polarization component and reflecting other polarization components to return to the light source side again. A polarization separation film 48 is provided. That is, by providing the polarization separation film 48, light of a polarization component that can be transmitted through the polarizer 41 can be selectively incident on the polarizer 41, and other light can be returned to the light source side. The light returned to the light source side can be incident again on the polarization separation film 48 with its polarization state changed by subsequent reflection or the like. “DBEF” (registered trademark) available from 3M USA can be used as the polarization separation film 48 that can be useful for improving luminance. In addition to “DBEF”, a high-intensity polarizing sheet “WRPS” available from Shinwha Intertek, Korea, a wire grid polarizer, or the like can be used as the polarizing separation film 48.

  Furthermore, a light diffusion sheet having a light diffusion function may be provided as an intermediate film 48 between the polarizer 41 of the lower polarizing plate 40 and the protective film 50. At this time, the light diffusion sheet may have an isotropic light diffusion function or an anisotropic light diffusion function. When the light diffusion sheet has an anisotropic light diffusion function, the direction in which the light diffusion function is strongly exerted by the light diffusion sheet is the arrangement direction of the unit optical elements 60 (as in the embodiment shown in FIG. 4). It may be parallel to the direction in which the light condensing function is exerted strongly, or may be parallel to the longitudinal direction of the unit optical element 60 (the direction in which the light condensing function is not exerted strongly).

  Furthermore, in the above-described embodiment, an example in which the light emitter 26 forming the light source 25 is disposed immediately below the polarizing plate 40 including the protective film 50 having a light control function, that is, a protective film having a light control function. Although the example in which the polarizing plate 40 including 50 is applied to the direct-type liquid crystal display device 10 is shown, it is not limited thereto. As shown in FIG. 15, the polarizing plate 40 including the protective film 50 having a light control function may be disposed at a position facing the light guide plate 23 that receives light from the light emitter 26.

  In the example shown in FIG. 15, the polarizing plate 40 is used together with a surface light source device 22 having a light emitter 26 and a light guide plate 23 that receives light from the light emitter 26, and is used as the light guide plate 23 of the surface light source device 22. Arranged to face. In this example, the optical module 20 includes a polarizing plate 40 and a light guide plate 23 disposed at a position facing the protective film 50 of the polarizing plate 40. In the example shown in FIG. 15, the liquid crystal display panel 15 including the polarizing plate 40 can be configured similarly to the above-described embodiment.

  In the example shown in FIG. 15, the surface light source device 22 includes a light guide plate 23, a light emitter 26 disposed on the side of the light guide plate 23, and a reflection sheet 21 a disposed on the back surface of the light guide plate 23. It has a so-called edge light type (side light type) backlight. Light from the light emitter 26 of the light source 25 enters the light guide plate 23 from the side surface (incident surface) of the light guide plate 23, and is guided through the light guide plate 23 while being repeatedly reflected between the pair of main surfaces of the light guide plate 23. Proceed along the direction. The light guide plate 23 is provided with light extraction elements (not shown), for example, white dots provided on the back surface of the light guide plate 23 facing the reflection sheet 21a, diffusion components dispersed in the light guide plate 23, and the like. Light traveling in the light guide plate 23 is emitted from the light guide plate 23 toward the observer so that the amount of emitted light is substantially uniform along the light guide direction. At this time, as shown in FIG. 15, a lot of light L181 emitted from the light guide plate 23 is emitted in a direction greatly inclined from the front direction nd.

  With respect to such a light guide plate 23, the unit optical elements 60 of the protective film 50 are arranged such that the arrangement direction thereof is parallel to the light guide direction of the light guide plate 23. The unit optical element 60 protrudes from the protective film 50 toward the light guide plate 23 side. Then, the light L181 directed toward the liquid crystal display panel along the direction greatly inclined from the front direction nd is incident on the protective film 50 via one surface 60b1 of the unit optical element 60, and then the other of the unit optical elements 60 The traveling direction is deflected toward the front direction nd side by reflecting (particularly total reflection) on the surface 60b2. In this way, the protective film 50 can exhibit a light collecting function.

  On the other hand, as shown in FIG. 17, a conventional edge light type surface light source device used in combination with a liquid crystal display panel including a conventional lower polarizing plate 13 often has a light output from a light guide plate 23. A condensing sheet (prism sheet, reflection type prism sheet, reverse prism sheet) C was provided on the side. For this reason, in the embodiment according to the present invention, the light collecting function of the protective film 50 is the same as the light collecting sheet (prism sheet, reflective prism sheet, reverse) included in the conventional surface light source device shown in FIG. By using the light collecting function of the prism sheet C), it is possible to omit the light collecting sheet C from the surface light source device while maintaining the optical characteristics of the display device 1 as a whole. Similarly, in the conventional surface light source device shown in FIG. 17, a light diffusion sheet D is provided on the light exit side of the light collecting sheet C. In the embodiment according to the present invention, the protective film 50 is provided. By including the diffusing component 59b, the light diffusing sheet D can be omitted by appropriately adjusting the degree of the light diffusing function caused by the diffusing component 59b. Thereby, also according to the aspect shown in FIG. 15, the same effect as the above-described embodiment can be obtained.

  Note that, in the conventional display device 1 shown in FIG. 17, the same reference numerals as those used for the already described configuration are used for portions that can be configured the same as the already described configuration. Therefore, duplicate explanation is omitted.

  Although several modifications to the above-described embodiment have been described above, a plurality of modifications can be applied in appropriate combination.

  In addition, in comparison with the conventional display device 1 in which a large number of optical sheets are included between the light-emitting body 26 or the light guide plate 23 forming the light source 25 and the liquid crystal display panel, according to one embodiment of the present invention. Although the advantages of the display device 10, the polarizing plate 40, and the protective film 50 have been described, such description describes the display device 10, the polarizing plate 40, and the protective film 50 according to an embodiment of the present invention on the light incident side. It is not excluded to use in combination with the optical sheet arranged in the above. That is, the present invention includes an embodiment in which one or more optical sheets are disposed between the display device 10, the polarizing plate 40, the protective film 50, and the light emitter 26 or the light guide plate 23. In this case, the excellent effects resulting from the protective film 50 can be enjoyed.

DESCRIPTION OF SYMBOLS 10 Display apparatus 11 Liquid crystal cell 15 Liquid crystal display panel 20 Optical module 25 Light source 26 Light emitter 40 Polarizing plate, lower polarizing plate 41 Polarizer 48 Intermediate film 49 Adhesive layer 49a Adhesive 49b Diffusion component 50 Protective film, optical sheet 50a Light emission side surface 50b Light incident side surface 51a Light diffusing layer 51b Resin layer 52 Land portion 54 Mat layer 55 Main body portion 55b Light incident side surface 58a Fine particles 58b Air gap portion 59a Base material portion 59b Diffusing component 60 Unit optical element

Claims (9)

A protective film for a polarizing plate that is joined to a polarizer from the light incident side to form a light incident side polarizing plate for a liquid crystal display panel,
A light diffusion layer including a base material portion made of a resin material and a diffusion component dispersed in the base material portion;
The diffusion component of the light diffusion layer has a refractive index isotropic property,
The said base material part of the said light-diffusion layer is a protective film which has refractive index anisotropy.   The said light-diffusion layer is a protective film of Claim 1 formed by uniaxially stretching the resin material which makes the said base material part by which the fine particle was disperse | distributed.   The protective film according to claim 2, wherein a refractive index of the diffusing component is equal to or lower than a refractive index of a fast axis of the base material portion.   The protective film according to claim 1, further comprising a plurality of unit optical elements forming a light incident side surface. The plurality of unit optical elements are arranged in a predetermined arrangement direction,
The protective film according to claim 4, wherein each unit optical element extends in a direction intersecting with an arrangement direction of the plurality of unit optical elements. A polarizing plate on the light incident side for a liquid crystal display panel,
A polarizer,
It is a protective film as described in any one of Claims 1-5, Comprising: The polarizing plate provided with the protective film joined to the said polarizer from the light-incidence side.   The polarizing plate according to claim 6, wherein a fast axis of the base portion of the light diffusion layer is parallel to a transmission axis of the polarizer.   A liquid crystal display panel provided with the polarizing plate as described in any one of Claims 1-7. A liquid crystal display panel according to claim 8;
A light-emitting body that illuminates the liquid crystal display panel from the protective film side.

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