JP5292457B2 - Viewing angle control system and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a viewing angle control system which can be used in a display device requiring peep prevention and viewing angle control and can control viewing angle of a display, and to provide an image display device. <P>SOLUTION: A viewing angle control system 100 comprises a first polarizer 1 and a second polarizer 2 each of which is film-shaped and contains absorption dichroic material. The first polarizer 1 has an absorption axis 1a in a film plane. In the second polarizer 2, an absorption axis 2a is inclined from a normal direction of a film plane, an angle between the absorption axis 2a and a normal line of the film plane is 0-45&deg;, and a plane including the normal line of the film plane of the second polarizer and the absorption axis 2a is angled substantially perpendicular to the absorption axis 1a of the first polarizer. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a viewing angle control system and an image display apparatus using the same.

  Image display devices such as liquid crystal display devices (LCD), plasma display devices (PDP), and EL display devices (ELD) have features such as being thin, lightweight, low power consumption, and capable of large screens. It is used in various applications and situations. In particular, LCDs and ELDs are widely used as display devices for personally used information devices such as notebook computers and mobile phones. Data such as personal information and trade secrets may be handled using such information equipment, but in public places such as station platforms, coffee shops, trains, etc., by looking into others , Privacy is infringed and confidential information is leaked. The same applies to an automatic teller machine (ATM) or the like, and there is a risk that information may be leaked due to a peep at the time of operation of a personal identification number or the like. On the other hand, in the case of an in-vehicle display such as a car navigation system, the light emitted upward from the display is reflected in the front window, and the external view is obstructed by the reflection particularly when driving at night. There is.

  Among the image display devices described above, the LCD is said to have “a narrow viewing angle” compared to a self-luminous display device such as a CRT, ELD, or PDP, and an optical compensation film is used to expand the viewing angle. Is used. In this case, the expression “the viewing angle is narrow” means that “the viewing angle showing good display characteristics is narrow”. In other words, even in a display device that is generally said to have a “small viewing angle”, display information is emitted in all directions, and the possibility of information being read by looking into others, reflections, etc. The problem is not solved. From this point of view, it is necessary to control the light quantity of the emitted light according to the angle so that the light emission in an unnecessary direction or a direction to be restricted cannot be read.

  In order to solve such a problem, a film in which an interdigital louver is physically formed between protective layers such as a PET film is used (see, for example, Patent Document 1). Such a film is also called a light control film or the like and is already on the market. As shown in FIG. 2, the film on which the louvers are formed is provided with a number of light-absorbing louvers 202 perpendicular to the protective layer 203 or at a predetermined angle. Various viewing angles can be controlled by adjusting the arrangement interval of the optical layer 201, the arrangement angle of the louver 202 and the protective layer 203, or by laminating a plurality of these structural units 200.

  As shown in Patent Document 1, such a louver film is formed by laminating a transparent layer serving as a translucent portion and a colored layer serving as a louver portion until a required size is obtained, and slicing it. Then, the protective layer is manufactured by a method of laminating on both sides. For this reason, there is a problem that manufacturing requires a very complicated process, is costly, and lacks flexibility in visual angle control design. In addition, there is a limit to the number of laminated transparent layers and colored layers, and the laminated thickness is a determining factor for the size of the louver film, so it is difficult to increase the area.

JP 2001-30531 A

  In view of the above, an object of the present invention is to provide a viewing angle control system and an image display device that can be used for a display device that requires peeping prevention and viewing angle control, and that can control the viewing angle of a display.

  The above object can be achieved by the present invention as described below. That is, the present invention has a film-form first polarizer and second polarizer containing an absorption dichroic substance having a fixed orientation, and the first polarizer has an absorption axis in the film plane. In the second polarizer, the absorption axis of the second polarizer is tilted from the normal direction of the film surface, the angle formed by the absorption axis and the normal line of the film surface is 0 ° to 45 °, and Further, the present invention relates to a viewing angle control system in which an angle formed by a plane including a normal line and an absorption axis of a film surface of a second polarizer and an absorption axis of the first polarizer is substantially perpendicular. Although the apparent absorption axis of the polarizer varies depending on the viewing direction, in the viewing angle control system of the present invention, two polarizers having different absorption axis directions are used, and the angular relationship between these apparent absorption axes and Viewing angle control is made possible by utilizing the fact that the light transmittance changes depending on the viewing direction.

  In the viewing angle control system of the present invention, an angle formed between a plane including the normal line of the film surface of the second polarizer and the absorption axis and the absorption axis of the first polarizer is 90 ° ± 5 °. Preferably there is. By arranging the two polarizers at such an angle, the viewing angle control characteristic can be made more remarkable.

  Further, in the viewing angle control system of the present invention, when a medium is provided between the first polarizer and the second polarizer, the medium transmits light in a direction normal to the film surface of the second polarizer. It is preferable that the polarization state is not substantially converted. This is because if the polarization state is converted by the medium between the first polarizer and the second polarizer, desired viewing angle control characteristics may not be obtained.

  As one aspect of one that does not substantially convert the polarization state of the light in the normal direction of the film surface of the second polarizer, an in-plane retardation of the medium is 40 nm or less. It is also a preferred aspect that the slow axis of the medium is parallel or perpendicular to the absorption axis of the first polarizer.

  Furthermore, in the viewing angle control system of the present invention, it is preferable that the thickness direction retardation of the medium is 60 nm or less in order to obtain desired viewing angle control characteristics.

  Furthermore, in the viewing angle control system of the present invention, it is preferable that the first polarizer and the second polarizer are bonded and integrated through an adhesive layer and / or an adhesive layer. By integrating and bonding, the occurrence of unevenness due to the shrinkage of the film can be suppressed, or the loss of light due to reflection can be reduced.

  Furthermore, as one aspect of the viewing angle control system of the present invention, an adhesive layer can be provided on at least one of the first polarizer side main surface and the second polarizer side main surface.

  Furthermore, the present invention relates to an image display device in which the viewing angle control system is arranged on at least one main surface of a display panel.

  In the image display device of the present invention, it is preferable that the first polarizer side main surface of the viewing angle control system is arranged to be on the display panel side. With such a configuration, the function of the polarizer of the display device and the polarizer of the viewing angle control system can be combined with a single polarizer.

  Furthermore, in the image display device of the present invention, it is preferable that the display panel and the viewing angle control system are bonded and integrated through an adhesive layer and / or an adhesive layer.

  As one aspect of the image display device of the present invention, at least one main surface of the display panel has a transparent plate, and the transparent plate and the viewing angle control system are arranged such that the second polarizer main surface side is What is laminated and integrated via an adhesive layer and / or an adhesive layer so as to be on the display panel side is also a preferable configuration.

  Furthermore, in the image display device of the present invention, it is preferable that the viewing angle limiting direction of the display device is perpendicular to the absorption axis direction of the first polarizer.

  As a preferred aspect of the image display device of the present invention, when the display panel is a liquid crystal display device having a polarizer on at least one main surface of a liquid crystal cell, the polarizer is the first viewing angle control system. It is also preferable to serve as a polarizer. By setting it as this aspect, the number of members can be reduced and it can contribute to thickness reduction, weight reduction, and cost reduction of a liquid crystal display device.

  As another preferable aspect of the image display device of the present invention, the display panel is a self-luminous display device, and the viewing angle control system is arranged on the viewing side of the display panel. In this aspect, it is preferable that circular polarization means for converting linearly polarized light into substantially circularly polarized light is provided between the first polarizer of the viewing angle control system and the display panel. Viewing angle control is possible by arranging the viewing angle control system on the viewing side of the display panel. Further, by having the circular polarization means, it is possible to provide an antireflection function, and it is possible to prevent a decrease in bright place contrast due to reflection at the interface of the self-luminous display device.

1 shows a cross section of a basic configuration of a viewing angle control system of the present invention. 1 shows an example of a cross section of a conventional visual angle control system in which a louver 202 is formed. It is explanatory drawing showing the visual recognition direction in case the absorption-axis direction of a 2nd polarizer is parallel to the normal line direction of a film surface. The solid line double arrow in the figure represents the absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. When the absorption axis direction of a 2nd polarizer is parallel to the normal line direction of a film surface, a mode that the relationship of the apparent absorption axis of a 1st polarizer and a 2nd polarizer changes with viewing directions typically. It is a representation. The solid line double arrow in the figure represents the absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. It is explanatory drawing showing the visual recognition direction in case the absorption-axis direction of a 2nd polarizer inclines with respect to the normal line direction of a film surface. The solid line double arrow in the figure represents the absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. When the absorption axis direction of a 2nd polarizer inclines with respect to the normal line direction of a film surface, a mode that the relationship of the apparent absorption axis of a 1st polarizer and a 2nd polarizer changes with visual recognition directions is modeled. It is a representation. The solid line double arrow in the figure represents the absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. It is the conceptual diagram which represented typically a mode that light reflected and refracted | refracted at the interface of a 2nd polarizer. The broken line double arrow in the figure represents the absorption axis direction of the second polarizer. 1 shows an example of a schematic cross section of a viewing angle control system according to the present invention. 1 shows an example of a schematic cross section of a viewing angle control system according to the present invention. 1 shows an example of a schematic cross section of a viewing angle control system according to the present invention. It is a block diagram which shows an example of a structure schematic cross section of the liquid crystal display device which is one embodiment of the image display apparatus of this invention. It is a block diagram which shows an example of a structure schematic cross section of the liquid crystal display device which is one embodiment of the image display apparatus of this invention. It is a block diagram which shows an example of a structure schematic cross section of the liquid crystal display device which is one embodiment of the image display apparatus of this invention. It is a block diagram which shows an example of a structure schematic cross section of the EL display apparatus which is one embodiment of the image display apparatus of this invention. It is a figure showing the evaluation result of the Example and comparative example of this invention. (A) shows Example 1, (b) shows Example 2, (c) shows the angle dependence of the white luminance of the image display apparatus of Comparative Example 1.

  The viewing angle control system of the present invention includes a first polarizer 1 and a second polarizer 2 as shown in FIG. As an optional configuration, a medium 30 such as an adhesive layer, an adhesive layer, or a protective film may be provided between the first polarizer and the second polarizer. The polarizer is an “O-type polarizer” having a transmission axis in the normal ray (O) axis direction and an absorption axis in the extraordinary ray (E) axis direction, and extraordinary ray (E). Although classified as “E-type polarizer” having a transmission axis in the axial direction and an absorption axis in the ordinary ray (O) axis direction, in the viewing angle control system of the present invention, the first polarizer, the second polarizer An O-type polarizer is used for both polarizers.

  The first polarizer used in the viewing angle control system of the present invention is formed in a film shape. As the first polarizer, a general O-type polarizer containing an absorbing dichroic substance and having the absorption axis 1a in the plane of the film can be used as appropriate. Examples of such polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and iodine and dichroic dyes. Known, such as uniaxially stretched by adsorbing chromatic substances, polyene-based oriented films such as polyvinyl alcohol dehydrated and polyvinyl chloride dehydrochlorinated, coated with liquid crystal dichroic dye, and oriented Things can be used.

  The first polarizer is often used also as a polarizer used in a normal liquid crystal display device, and is not particularly limited as long as it can be generally used as a polarizer of a liquid crystal display device. From the viewpoint of polarization performance such as degree, an iodine-based linear polarizer can be suitably used. From the viewpoint of durability, a dye-based or polyene-based polarizer can be preferably used.

  The second polarizer used in the viewing angle control system of the present invention is formed in a film shape. As the second polarizer, one containing an absorption dichroic material and having an angle between 0 ° to 45 ° formed by the normal axis of the absorption axis 2a and the film surface is used. Although details of the viewing angle control principle by the viewing angle control system of the present invention will be described later, the viewing angle characteristics and the visibility such as transmittance are easily affected by the optical characteristics of the second polarizer. Therefore, the higher the polarization characteristics of the second polarizer, the better.

  Although the material and manufacturing method of such a polarizer are not particularly limited, those obtained by aligning a dichroic compound in a liquid crystal polymer matrix can be suitably used. In particular, from the viewpoint of improving the vertical alignment and achieving a high dichroic ratio, it is preferable to align the liquid crystal compound with a vertical alignment substrate.

Examples of the substrate that can vertically align the liquid crystal compound include glass substrates, metal plates such as aluminum and stainless steel, inorganic materials such as inorganic oxides, and organic materials. As a glass substrate, in addition to general plate glass, a thin plate glass film (for example, # 100, AF35 manufactured by Matsunami Glass Industry Co., Ltd.) that can be formed into a thickness of 0.1 mm or less and wound into a roll, The resin film etc. which bonded this are mentioned. Examples of the metal plate include aluminum and stainless steel plates, thin plates thereof, or those obtained by plating / depositing these on a resin film. Specifically, for example, an aluminum vapor-deposited PET film or stainless steel vapor-deposited film manufactured by Toyo Metallizing Co., Ltd. or Oike Kogyo Co., Ltd., a rolled aluminum foil manufactured by Toyo Aluminum Co., Ltd., a rolled aluminum foil with a PET substrate, or the like can be given. Examples of the inorganic oxide include SiO ₂ vapor-deposited PET film and ITO vapor-deposited PET film manufactured by Oike Kogyo Co., Ltd. As the organic material, a film made of a hydrophobic resin can be suitably used, and examples thereof include norbornene resins and fluorine resins. Examples of the norbornene-based resin include an unstretched film of ZEONOR manufactured by Optes. Examples of the fluorine-based resin include Teflon (registered trademark) resin film manufactured by DuPont, and ETFE and PTFE (polytetrafluoroethylene) manufactured by Asahi Glass. In the case of using an opaque base material such as a metal plate or a deposit of an inorganic oxide as the base material for aligning the liquid crystal compound, after forming the alignment layer of the liquid crystal compound on the base material, It is preferable to use what was transcribe | transferred to base materials with high light transmittances, such as a transparent film, as a polarizer.

  Examples of the liquid crystal polymer matrix include thermotropic liquid crystalline polymers and crosslinkable liquid crystalline polymers. JP-A-11-101964, JP-A-11-160538, JP-A-2001-330726, JP-A-2001-133630 are examples in which a dichroic dye is aligned in such a liquid crystal polymer matrix. Gazette, JP-A-2005-99065, Nitto Giho Vo135, No. 1, p79, (1997), and the like.

  In particular, in order to increase the orientation, a method of fixing the orientation by applying a mixture of a liquid crystal monomer having a polymerizable functional group and a dichroic dye on a substrate and polymerizing the liquid crystal polymer by irradiation with ultraviolet rays or the like. Can be suitably used. Thus, by superposing | polymerizing on an orientation base material, since orientation is fixed, since orientation is fixed, it is preferable also at the point which durability improves. Furthermore, upon such irradiation, the orientation can be further improved by applying an electric field or magnetic field in the direction in which the liquid crystal molecules are to be aligned, for example, the normal direction or oblique direction of the film surface, or the alignment direction can be controlled. it can.

  Moreover, an additive can also be used for the purpose of improving the vertical alignment. Examples of the additive for enhancing the vertical alignment include a monomer unit containing a liquid crystalline fragment side chain having positive refractive index anisotropy and a monomer unit containing a non-liquid crystalline fragment side chain. A side chain type liquid crystal polymer is mentioned. As such a liquid crystal compound, for example, those described in JP-A No. 2003-149441 can be used.

  The dichroic dye exhibits different absorbances between the major axis and the minor axis of the molecule with respect to incident light, and the major axis of the molecule is aligned in the predetermined direction according to the uniaxial orientation of a liquid crystal polymer or the like. The vibration component contained in the incident light is selectively absorbed and transmitted to be converted into polarized light. The dye having a high dichroic ratio is preferably an azo, perylene, pentacene, or anthraquinone dye, or a mixed dye thereof, which is preferably used for a dye-based polarizer. For example, JP-A-54-76171. Detailed in the gazette. Further, instead of blending a dichroic dye into the liquid crystal polymer matrix, a material containing a liquid crystalline dichroic dye as described in, for example, JP-A-2005-140986 can also be used. The dichroic dye may be used alone or in combination of two or more depending on the wavelength range of the polarization characteristics, and the amount used is generally 1 to 20% by weight based on the liquid crystal polymer or liquid crystal monomer.

  The dichroic ratio of the second polarizer is preferably high as described above. However, when a dichroic dye is used in the matrix of the thermotropic liquid crystalline polymer or the crosslinkable liquid crystalline polymer, the dichroic ratio is 25. It is preferable that it is above, more preferably 30 or more, and further preferably 50 or more.

Although the dichroic ratio of a polarizer having an absorption axis other than in the film plane cannot be directly measured, in the present specification, the value is defined as follows. First, let K _{1 be} the transmittance in the normal direction of the second polarizer, that is, the absorption axis direction. Here, although linearly polarized light is originally used as incident light, since the second polarizer is vertically oriented, the transmittance of natural light and the transmittance of linearly polarized light are considered to be equivalent, and the transmittance of natural light is defined as K ₁ . To do.

Next, in order to measure the transmission axis direction of the transmittance K _2, to create a polarizer of horizontal alignment with the same composition. Such a horizontally aligned polarizer can be obtained by spreading, aligning and fixing a solution containing a liquid crystal compound having the same composition as that of the second polarizer on the horizontal alignment film. At this time, as the horizontal alignment film, an alignment film formed by rubbing polyimide on a glass plate is used. In order to fix the alignment, a horizontal electric field of 2 kV is applied in the rubbing direction of the alignment film, and in the presence of the electric field, the liquid crystal monomer is aligned by heating and then slowly cooling, and then UV irradiation is performed to fix the alignment. The absorption axis of the horizontal alignment polarizer thus produced, that is, linearly polarized light parallel to the alignment direction is incident, and the transmittance K ₂ is obtained.

Using K ₁ and K ₂ obtained in this way, the dichroic ratio D is
D = log K ₂ / log K ₁
It is represented by In measuring the dichroic ratio, strictly speaking, it is necessary to consider the influence of the surface reflection loss of the film, but since the influence can be ignored, the above formula is used in this specification.

From the above measurement method and the above formula, when the vertical alignment property of the second polarizer that is vertically aligned is low, the light in the normal direction of the film is absorbed by the dichroic material, so that the above transmission the value of the rate K ₁ becomes small, resulting dichroism is can be seen that low.

  The principle of controlling the viewing angle of the display device by the viewing angle control system of the present invention will be described. The viewing angle control system of the present invention uses the apparent absorption axis direction of the polarizer and the fact that the light transmittance changes depending on the viewing angle, and controls the amount of emitted light according to the viewing angle. Light emission in a desired direction or a direction to be restricted.

  FIG. 3 shows aspects of various viewing directions. The apparent change in the absorption axis direction will be described with reference to FIG. When viewed from the normal direction of the film surface as in the viewing direction (a), that is, from the front direction of the polar angle θ = 0 °, or in the oblique direction of polar angle θ ≠ 0 as in the viewing direction (b) Even in this case, the direction of the azimuth angle is the same as the absorption axis, that is, the direction of the azimuth angle ψ = 0 ° or 180 ° (however, the absorption axis direction of the first polarizer is used as a reference for the azimuth angle ψ = 0 °). Or, when viewed from the direction in which the azimuth angle is perpendicular to the absorption axis as in the viewing direction (c1) or (c2), that is, from the direction of the azimuth angle ψ = 90 ° or 270 °, the direction of the apparent absorption axis Does not change. On the other hand, when viewed from an oblique direction other than those described above, the apparent azimuth angle of the absorption axis changes so that the angle formed with the azimuth angle in the viewing direction becomes larger.

  In the viewing angle control system of the present invention, when the absorption axis direction of the second polarizer is substantially parallel to the normal direction of the film surface, the amount of emitted light is controlled by the viewing angle. This will be described based on the change in the apparent absorption axis direction of the polarizer.

  (A), (b), (c1), and (c2) in FIG. 4 respectively represent the apparent absorption axis directions in the viewing directions (a), (b), (c1), and (c2) in FIG. Represents. In addition, the solid line double arrow represents the apparent absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. As seen from the viewing direction (a) in FIG. 3, when viewed from the front direction, that is, the polar angle θ = 0 °, the viewing angle control system is viewed from the direction parallel to the absorption axis of the second polarizer. In this case, as shown in FIG. 4A, since the absorption by the dichroic substance of the second polarizer does not occur, the light emitted from the first polarizer passes through the second polarizer as it is. . Actually, the transmission axis direction of the dichroic material, that is, the ordinary ray (O) axis direction is not completely transparent, and the orientation of the dichroic material is not completely unidirectional. Therefore, although some absorption occurs, since the anisotropy in the film plane is negligible, no polarization occurs. Therefore, in the front view, the polarization state of the light emitted from the first polarizer is not converted by the second polarizer except that there is slight absorption.

  As shown in the viewing direction (b) in FIG. 3, the first polarizer has an absorption axis and an azimuth angle that are the same, that is, the polar angle θ ≠ 0 °, and the azimuth angle ψ = 0 ° or 180 ° (provided that When viewed from the direction of the absorption axis direction of the first polarizer (with the azimuth angle ψ = 0 ° as a reference), the absorption axis of the second polarizer is the first as shown in FIG. Since it is apparently parallel to the absorption axis of the polarizer, that is, in a parallel Nicol state, the light emitted from the first polarizer is hardly absorbed by the second polarizer. Even when the viewing angle increases, that is, the polar angle θ increases, the amount of light transmitted through the viewing angle control system of the present invention remains large.

  On the other hand, as shown in the viewing directions (c1) and (c2) of FIG. 3, the azimuth is perpendicular to the absorption axis, that is, the polar angle θ ≠ 0 ° and the azimuth ψ = 90 ° or 270 °. When viewed from above, the absorption axis of the second polarizer apparently appears in a direction parallel to the viewing direction. Since the absorption axis of the first polarizer does not change apparently, as shown in FIGS. 4C1 and 4C2, the absorption axis of the second polarizer is perpendicular to the absorption axis of the first polarizer, that is, The light emitted from the first polarizer is absorbed by the second polarizer because of the crossed Nicols relationship. In addition, since the viewing angle increases, that is, the polar angle θ increases and the absorption vector component in the extraordinary light (E) axis direction increases, the absorbance increases and the optical path length increases. Light absorption is increased by the polarizer. Therefore, when viewed from the direction perpendicular to the absorption axis of the first polarizer, the amount of light transmitted through the viewing angle control system of the present invention decreases as the viewing angle increases, and display information of the display device when viewed from this direction. Becomes remarkably difficult to see, and viewing angle control is achieved.

  Here, the viewing directions (c1) and (c2) in FIG. 3 represent viewing directions having the same polar angle θ and different azimuth angles of 180 °, but are shown in (c1) and (c2) in FIG. Thus, since the apparent arrangement of the absorption axis 2a of the second polarizer is the same, the light absorption by the second polarizer is also the same. That is, it can be seen that the target viewing angle control characteristic is shown with respect to the normal of the film surface.

  Further, the viewing angle control system of the present invention is viewed from a viewing direction other than the above, that is, from a direction in which the polar angle θ ≠ 0 ° and the azimuth angle ψ is neither 0 °, 90 °, 180 °, or 270 °. When viewed, the transmittance decreases based on the angle formed by the absorption axes of the first polarizer and the second polarizer. The apparent absorption axis of the first polarizer changes according to the polar angle θ and the azimuth angle ψ in the viewing direction, and the magnitude of this change is the azimuth angle ψ = 45 °, 135 °, 225 °, 315 It becomes maximum in the direction of °, and increases as the polar angle θ increases. The apparent azimuth of the absorption axis of the second polarizer is equal to the azimuth of the viewing direction. The light absorption amount of the second polarizer increases as the polar angle θ increases due to the relationship of the optical path length.

  Thus, the transmittance of the viewing angle control system of the present invention is determined based on the angle formed by the apparent absorption axes of the first polarizer and the second polarizer and the amount of light absorption varies depending on the viewing direction. The viewing angle of the display device can be limited. That is, as the azimuth angle in the viewing direction is farther from the absorption axis direction of the first polarizer, the transmittance of the viewing angle control system of the present invention decreases, and as the polar angle θ increases, the transmission of the viewing angle control system of the present invention increases. The rate decreases. As a result, viewing angle control is achieved when the viewing angle control system of the present invention is combined with a display device.

  Next, the case where the absorption axis of the second polarizer is tilted from the normal direction of the film surface in the viewing angle control system of the present invention will be described. In such a case, the angle formed between the absorption axis of the second polarizer and the normal line of the film surface is 45 ° or less, as described above. It is preferable that an angle formed by the surface including the absorption axis and the absorption axis of the first polarizer is substantially perpendicular. Here, “substantially vertical” refers to a range of 90 ° ± 5 °, preferably 90 ° ± 3 °, and more preferably 90 ° ± 2 °. By setting it as such an angle range, the viewing angle control system which gave the directivity to the viewing angle control range can be obtained. Hereinafter, when the angle formed by the plane including the normal line and the absorption axis of the second polarizer and the absorption axis of the first polarizer is perpendicular, the amount of emitted light is controlled by the viewing direction. Will be described based on the apparent change in the absorption axis direction of the first polarizer and the second polarizer.

  FIG. 5 shows aspects of various viewing directions. (A), (b), (c1), (c2), and (d) of FIG. 6 are respectively in the viewing directions (a), (b), (c1), (c2), and (d) of FIG. Represents the apparent absorption axis direction. In addition, the solid line double arrow represents the absorption axis direction of the first polarizer, and the broken line double arrow represents the absorption axis direction of the second polarizer. When viewed from the front direction, that is, the polar angle θ = 0 ° as in the viewing direction (a) in FIG. 5, the absorption axis component of the second polarizer is generated as shown in FIG. 6 (a). . Therefore, as shown in FIG. 4A described above, the transmittance decreases compared to the case where the absorption axis of the second polarizer is parallel to the normal direction of the film surface. However, since the angle formed between the absorption axis of the second polarizer and the film normal is 45 ° or less, the amount of light absorbed by the second polarizer is small, and the loss of transmittance in the front view is small.

  As seen from the viewing direction (b) in FIG. 5, the first polarizer is viewed from the oblique direction with the same azimuth angle as the absorption axis, that is, the polar angle θ ≠ 0 and the azimuth angle ψ = 0 ° or 180 °. In this case, as shown in FIG. 6B, the apparent absorption axis of the second polarizer is an angle close to parallel to the absorption axis of the first polarizer, so that the decrease in transmittance is small. . However, compared with the case of FIG. 4B in which the apparent absorption axes of the first polarizer and the second polarizer are parallel, light is absorbed by the second polarizer, although slightly. Its transmittance is small.

  On the other hand, as shown in the viewing directions (c1) and (c2) in FIG. 5, the azimuth angle is perpendicular to the absorption axis direction of the first polarizer, that is, the polar angle θ ≠ 0, and the azimuth angle ψ = When viewed from the direction of 90 ° or 270 °, it is assumed that the angle formed between the plane including the normal line of the film surface of the second polarizer and the absorption axis is perpendicular to the absorption axis of the first polarizer Is observed from an in-plane direction including the normal line of the film surface of the second polarizer and the absorption axis. In this case, the apparent absorption axis of the second polarizer appears in a direction orthogonal to the absorption axis of the first polarizer, that is, the apparent absorption axis of both is in the relationship of orthogonal Nicols, so that the transmitted light Is greatly attenuated.

  Here, the viewing directions (c1) and (c2) in FIG. 5 are the same as in the viewing directions (c1) and (c2) in FIG. It represents the direction. As shown in (c1) and (c2) of FIG. 6, the viewing direction (c1) in FIG. 5 where the angle formed by the absorption axis 2a of the second polarizer is large is compared with the case of (c1) in FIG. In the case of the viewing direction (c2) in FIG. 5 where the angle formed with the absorption axis 2a of the second polarizer is small while the second polarizer increases light absorption, (c2) in FIG. Compared with the case of the above, it can be seen that the second polarizer reduces the light absorption, and exhibits a non-target viewing angle control characteristic with respect to the normal of the film surface.

  Further, when the second polarizer has a direction parallel to the absorption axis direction of the second polarizer, that is, when the angle formed by the viewing direction and the absorption axis direction is zero, as in the viewing direction (d) of FIG. 5, (d) of FIG. As shown in FIG. 4, since the absorption by the dichroic substance of the second polarizer does not occur, the light emitted from the first polarizer passes through the second polarizer as it is. This is the same as the case of FIG. 4A described above, and the polarization state of the light emitted from the first polarizer is not converted by the second polarizer except that there is slight absorption. On the other hand, the greater the angle between the viewing direction and the absorption axis direction, the greater the light absorption by the second polarizer.

  As described above, the viewing angle control system of the present invention utilizes the principle that the amount of light absorbed by the second polarizer varies depending on the viewing direction. In particular, the viewing directions (c1) and (c2) in FIG. As in the viewing directions (c1) and (c2) in FIG. 5, the polar angle of the viewing direction is changed in the direction in which the absorption axis of the first polarizer and the azimuth angle of the viewing direction form an angle of 90 °. In this case, the change in the amount of light absorption is large, that is, the viewing angle control characteristic in that direction is most remarkable. Further, when viewed from a direction parallel to the absorption axis direction of the second polarizer, such as the viewing direction (a) in FIG. 3 and the viewing direction (d) in FIG. 5, almost no light is emitted by the second polarizer. It is not absorbed and has the maximum transmittance (this direction is defined as the “main transmission direction”).

  For example, when the viewing angle control in the vertical direction of the image display device is performed using such a principle, the first polarizer is arranged so that the absorption axis direction of the first polarizer is equal to the horizontal direction of the screen. The desired viewing angle control can be achieved.

  By the way, in the explanation of the principle of the viewing angle control system, in order to explain the principle more simply, the refraction phenomenon at the material interface is ignored, but in reality, the light propagating in the second polarizer is on the viewer side. When emitted, the difference in refractive index between the second polarizer and the viewing side (usually air) affects the viewing angle control effect. That is, the lower the refractive index of the second polarizer, the narrower the transmission angle in the viewing angle control direction, and the higher the refractive index, the wider the transmission angle. This is because the propagation direction changes when light is emitted from the second polarizer to the viewer side based on Snell's law explaining the refraction phenomenon.

FIG. 7A shows the case where the absorption axis direction of the second polarizer is inclined by θ ₂ from the normal direction of the film surface, and the absorption axis direction of the second polarizer and the plane including the film normal line The state of light propagation is schematically shown. As in the case of the viewing direction (d) in FIG. 5, the light 51 propagating in the second polarizer in the direction parallel to the absorption axis 2 a is partially reflected as reflected light 52 at the interface of the second polarizer. The remaining light is emitted to the viewing side as transmitted light 53. At this time, since the refractive index on the viewing side is different from that of the second polarizer, light is refracted in the direction of the polar angle θ ₁ and emitted according to Snell's law expressed by the following (Equation 1).

n ₁ × sin θ ₁ = n ₂ × sin θ ₂ (Formula 1)
However, n ₁ is the refractive index on the viewing side, and normally the refractive index of air n ₁ ≈1. N ₂ is the refractive index of the second polarizer.

The above (Formula 1) can be rewritten as the following (Formula 2).
sin θ ₁ = (n ₂ / n ₁ ) × sin θ ₂ (Formula 2)

Since n ₂ > n ₁ in general, as shown in FIG. 7B, when the inclination θ ₂ from the normal direction of the film surface of the absorption axis of the second polarizer increases, sin θ ₁ > 1. Therefore, there is no θ ₁ that satisfies the above (Equation 1). That is, the light 51 propagating in the direction parallel to the absorption axis 2a is reflected as reflected light 52 at the interface of the second polarizer, and is so-called total reflection that it is not emitted to the viewing side. When total reflection occurs, light in the “main transmission direction” that maximizes the transmittance is not emitted to the viewer side, and thus the light use efficiency of the display device tends to decrease.

In order to prevent total reflection, it is necessary that the absorption axis tilt angle θ _{2 of} the second polarizer is smaller than the critical angle θ _{M of} total reflection. The critical angle can be expressed by the following (formula 3) or (formula 4).
sin θ _M = (n ₁ / n ₂ ) (Formula 3)
θ _M = sin ⁻¹ (n ₁ / n ₂ ) (Formula 4)

For example, when the viewing side is air (n ₁ = 1) and the refractive index n ₂ of the second polarizer is 1.5, the light in the main transmission direction does not cause total reflection. The absorption axis inclination angle θ ₂ needs to be smaller than sin ⁻¹ (1 / 1.5) ≈42 °, which is the critical angle θ _M. That is, when the refractive index of the second polarizer is 1.5, only light in a range of ± about 42 is radiated to the viewer side by refraction among the light emitted from the second polarizer. _{If 2} is larger than this, the main transmission direction θ ₁ corresponding to (d) of FIG. 7 does not exist.

When the refractive index of the material forming the second polarizer is larger than 1.5, the critical angle θ _M is smaller than 42 °, and conversely, the refractive index of the material forming the second polarizer is smaller than 1.5. If it is small, the critical angle θ _M is larger than 42 °.

As described above, in addition to the critical angle θ _M being different depending on the refractive index of the second polarizer, the definition of the refractive index is more complicated because the second polarizer has birefringence and is accompanied by light absorption. It becomes. Therefore, it is difficult to unconditionally define a preferable range of the inclination θ ₂ from the normal direction of the film surface of the absorption axis of the second polarizer, but in practice, θ ₂ is in the range of 0 to 45 °. I just need it.

However, when the polar angle θ ₁ in the viewing direction increases, the surface reflection increases as represented by the following (formula 5) and (formula 6). In particular, the increase in the reflectance R _s of the S-polarized light that becomes the transmitted light is remarkable as compared with the reflectance R _p of the P-polarized light.
R _s = (sin (θ ₁ −θ ₂ ) / sin (θ ₁ + θ ₂ )) ² (Formula 5)
R _p = (tan (θ ₁ −θ ₂ ) / tan (θ ₁ + θ ₂ )) ² (Formula 6)

Furthermore, when the polar angle in the viewing direction becomes extremely large, in addition to the increase in surface reflection as described above, the optical path length of the light propagating through the polarizer becomes long and the absorption becomes large. From this viewpoint, θ ₂ is preferably 0 to 40 °, and more preferably 0 to 30 °.

  As shown in FIG. 1, a medium 30 may be provided between the first polarizer 1 and the second polarizer 2 used in the viewing angle control system of the present invention. The medium 30 is illustrated in FIG. As shown, the protective films 11, 12, 21, and 22 for the polarizer, the adhesive layer 3 for bonding the polarizer to the polarizer, or the adhesive layer 4 may be included.

  By the way, in the viewing angle control system of the present invention, as described above, the viewing angle can be controlled by changing the angular relationship between the apparent absorption axes of the first polarizer and the second polarizer. Therefore, when the polarization state changes depending on the medium between the first polarizer and the second polarizer, a desired viewing angle control effect may not be obtained. From such a viewpoint, the medium between the first polarizer and the second polarizer does not substantially convert the polarization state of light incident in the film normal direction of the second polarizer. It is preferable.

  In order for the polarization direction in the film normal direction, that is, in the front view, not to be substantially converted, the medium between the first polarizer and the second polarizer has a substantially in-plane retardation. Preferably not. Here, “having substantially no in-plane retardation” means that the in-plane retardation Re is 40 nm or less, and the in-plane retardation Re is preferably 20 nm or less, more preferably 10 nm. Or less, more preferably 5 nm or less.

  In addition, even when the medium between the first polarizer and the second polarizer has an in-plane phase difference, the direction in which the refractive index is maximum, that is, the slow axis direction is the first polarization. It is preferably parallel or perpendicular to the absorption axis of the child. Here, the parallel or vertical does not need to be strictly parallel or vertical, and includes a range of 0 ° ± 5 ° or 90 ° ± 5 °. The angle range is preferably 0 ± 3 °, or 90 ° ± 3 °, and more preferably 0 ° ± 1 °, or 90 ° ± 1 °. Even when the medium between the first polarizer and the second polarizer does not substantially have an in-plane retardation, the medium is delayed from the viewpoint of minimizing the change in the polarization state in the front view. The angle formed by the phase axis direction and the absorption axis of the first polarizer is preferably in the above range.

  Further, from the viewpoint of obtaining a desired viewing angle control effect even in the oblique direction, it is preferable that the thickness direction retardation Rth of the medium between the first polarizer and the second polarizer is small. Specifically, the thickness direction retardation Rth is preferably 60 nm or less, more preferably 40 nm or less, and further preferably 30 nm or less.

Here, the in-plane phase difference Re, the thickness direction phase difference Rth, and NZ to be described later are the refractive index in the slow axis direction in the plane of the medium nx, the refractive index in the fast axis direction ny, and the thickness direction retardation ny. When the refractive index is nz and the thickness of the film is d, it is defined by the following formula.
Re = (nx−ny) d
Rth = (nx−nz) d
NZ = Rth / Re
= (Nx-nz) / (nx-ny)

  As described above, the slow axis direction of the medium between the first polarizer and the second polarizer is preferably parallel or perpendicular to the absorption axis of the first polarizer. In consideration of the influence of the phase difference in the first polarizer, the apparent change direction of the slow axis of the medium between the first polarizer and the second polarizer accompanying the change in the viewing direction is the apparent direction of the first polarizer. It is preferable to coincide with the change direction of the absorption axis. This is because the influence of the phase difference of the medium on the viewing angle control is reduced when the change directions of the two coincide. The direction of change of the slow axis of the medium between the first polarizer and the second polarizer is determined by the NZ of the medium. In the case of a normal O-type polarizer, the change in the apparent absorption axis accompanying the change in the viewing direction is the same as the change in the apparent slow axis of the retardation film with NZ = 1. From this viewpoint, it is preferable that NZ of the medium between the first polarizer and the second polarizer is close to 1.

  In addition, when the NZ of the medium between the first polarizer and the second polarizer is 0.5, the apparent slow axis direction does not change regardless of the viewing direction. When NZ of the medium is smaller than 0.5, the apparent slow axis changing direction at an oblique viewing angle is opposite to that when NZ = 1. Therefore, when the NZ of the medium between the first polarizer and the second polarizer is greater than 0.5, the slow axis direction of the medium is preferably parallel to the absorption axis direction of the first polarizer, When NZ is smaller than 0.5, it is preferably vertical. Further, when NZ = 0.5, the change of the slow axis hardly occurs, so that either parallel or vertical may be used.

  As a medium between the first polarizer and the second polarizer, for example, as shown in FIG. 8, a plurality of films, an adhesive layer, an adhesive layer, and the like may be included. In such a case, even if an individual film or the like does not satisfy the above-described optical characteristics, a combination of these plural layers is regarded as the medium 30 as long as it satisfies the optical characteristics described above. Explaining with a typical example, in FIG. 8, a film having characteristics of Re = 0 nm and Rth = + 100 nm (so-called negative C plate) is used as the protective film 11 of the first polarizer 1, and the second polarizer is used. As the protective film 22 of No. 2, a film having characteristics of Re = 0 nm and Rth = −100 nm (so-called positive C plate) is used, and these are bonded with the adhesive layer 4 and / or the adhesive layer 3 having no birefringence. This is the case. In this case, each medium has an absolute value of Rth larger than 60 nm and it is difficult to say that the medium has optical isotropy. However, when these media are laminated, an optical isotropic medium with Re = 0 nm and Rth = 0 nm is obtained. Therefore, it can be suitably used.

(Protective film)
The first polarizer and the second polarizer used in the viewing angle control system of the present invention can be used as a polarizing plate by appropriately bonding a protective film on one side or both sides thereof. In particular, an iodine-based polarizer or a polarizer using a liquid crystal material preferably has a protective film on both sides from the viewpoint of preventing sublimation of the dichroic substance and ensuring film strength.

  As a material constituting the protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and the like is used. Specific examples of such thermoplastic resins include polycarbonate resins, polyvinyl alcohol resins, cellulose resins, polyester resins, polyarylate resins, polyimide resins, cyclic polyolefin resins, polysulfone resins, polyether sulfones. Resin, polyolefin resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. Further, a thermosetting resin such as urethane, acrylic urethane, epoxy, or silicone, or an ultraviolet curable resin can also be used. The protective film may contain one or more arbitrary appropriate additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When content of the said thermoplastic resin in a protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  As described above, as the protective film serving as a medium between the first polarizer and the second polarizer, a film having optical isotropy can be preferably used. From this viewpoint, a cellulose resin is generally used. . As the cellulose resin, an ester of cellulose and a fatty acid is preferable. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose, and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercial products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Film Co., Ltd. -TAC "and" KC series "manufactured by Konica Minolta. In general, these triacetyl celluloses have almost no in-plane retardation, but have a thickness direction retardation of about 60 nm.

  In addition, the cellulose film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base material such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). After that, a method of peeling the substrate; a solution obtained by dissolving a cyclic polyolefin resin, a (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose film and dried by heating (for example, For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes.

  Moreover, as a cellulose film with a small thickness direction retardation, the fatty acid cellulose film which controlled the substitution degree by a fatty acid can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. By adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid cellulose resin, Rth can be controlled to be small. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Further, as a protective film having optical isotropy, a thermoplastic resin having a substituted and / or unsubstituted imide group in a side chain described in JP-A-2001-343529 (WO01 / 37007) and the like, and a side chain are substituted. And / or a polymer film containing a resin composition containing a non-substituted phenyl and a thermoplastic resin having a nitrile group, JP-A 2000-230016, JP-A 2001-151814, JP-A 2002-120326, JP-A-2002-254544, JP-A-2005-146084, JP-A-2006-171464, etc., a polymer film containing an acrylic resin having a lactone ring structure, JP-A-2004-70290, JP 2004-70296, JP 2004-163924, JP 004-292812, JP-A 2005-314534, JP-A 2006-131898, JP-A 2006-206881, JP-A 2006-265532, JP-A 2006-283013, JP-A 2006-2006. Polymer film containing an acrylic resin having a structural unit of unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride described in Japanese Patent Application Laid-Open No. 299905, Japanese Patent Application Laid-Open No. 2006-335902, and the like, Japanese Patent Application Laid-Open No. 2006-309033 JP, 2006-317560, JP, 2006-328329, JP, 2006-328334, JP, 2006-337491, JP, 2006-337492, JP, 2006-337493, JP, Open 2006-337568 It is also possible to use a film or the like containing a thermoplastic resin having a glutarimide structure described equal. Since these films have a small phase difference and a small photoelastic coefficient, they can eliminate problems such as unevenness due to the distortion of the polarizing plate, and since the moisture permeability is small, they are durable in a high humidity environment. It is preferable also in the point which is excellent.

  Moreover, it is also preferable to use a cyclic polyolefin resin as a protective film having optical isotropy. Specifically, the cyclic polyolefin resin is preferably a norbornene resin. The cyclic polyolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And the graft polymer which modified these with unsaturated carboxylic acid or its derivative (s), and those hydrides, etc. are mentioned. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “ARTON” manufactured by JSR, “TOPASS” manufactured by TICONA, and “APEL” manufactured by Mitsui Chemicals, Inc. Is mentioned.

  Although the thickness of a protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and a handleability, and thin-layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. If the thickness of the protective film is excessively small, the polarizer may be inferior in durability in a high-temperature and high-humidity environment, or may cause problems such as local unevenness defects (knic defects).

  The same protective film may be used on both sides of the polarizer, or different ones may be used. In addition, a laminate of two or more layers can be used on one surface.

  The method of laminating the first polarizer or the second polarizer and the protective film, or the method of laminating the polarizer and the protective film are not particularly limited, but from the viewpoint of workability and light utilization efficiency, It is desirable to laminate each layer without an air gap using an adhesive or a pressure-sensitive adhesive. When using an adhesive or a pressure-sensitive adhesive, the type thereof is not particularly limited, and various types can be used. In that case, the adhesive or pressure-sensitive adhesive is transparent, has no absorption in the visible light region, and the refractive index is desirably as close as possible to the refractive index of each layer from the viewpoint of suppressing surface reflection. From this viewpoint, for example, an acrylic pressure-sensitive adhesive or a water-based adhesive can be preferably used. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, and a water-based polyester. A diffusion adhesive layer in which particles having different refractive indexes are mixed with an adhesive can also be used.

  In the present invention, the polarizer, the protective film, the adhesive layer, the adhesive layer, and the like include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like. What gave the ultraviolet absorptivity by systems, such as a system processed with a ultraviolet absorber, etc. may be used.

  Attaching the pressure-sensitive adhesive layer or adhesive layer to the film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. Examples thereof include a method in which it is directly attached on a film by an appropriate development method such as a casting method or a coating method, or a method in which an adhesive layer is formed on a separator according to the above and transferred.

  The pressure-sensitive adhesive layer and the adhesive layer can be provided on one side or both sides of the film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a film.

  Further, the protective film may be subjected to a surface modification treatment for the purpose of improving adhesiveness before attaching an adhesive or a pressure-sensitive adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

  Furthermore, a surface of the protective film on which the polarizer is not adhered may be provided with a hard coat layer, antireflection treatment, antisticking, or a surface treatment layer for the purpose of diffusion or antiglare.

  The hard coat layer is provided for the purpose of preventing scratches on the surface of the polarizing plate. For example, a hard film with an appropriate UV curable resin such as acrylic or silicone is applied to the surface of the protective film. It can be formed by a method added to the above. The antireflection layer is provided for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. The anti-sticking layer is provided for the purpose of preventing adhesion with an adjacent layer (for example, a diffusion plate).

  The anti-glare layer is provided for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering the viewing of the light transmitted through the polarizing plate. For example, a roughening method using a sandblasting method or an embossing method, It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure.

  The antireflection layer, anti-sticking layer, surface treatment layer such as a diffusion layer and an antiglare layer can be provided on the protective film itself, and can also be provided as a separate optical layer from the protective film. .

  In particular, in the viewing angle control system of the present invention, as illustrated in FIG. 8, the surface treatment layer 23 may be provided on the protective film 21 on the main surface of the second polarizer 2 opposite to the first polarizer. preferable.

  Moreover, in the viewing angle control system of this invention, as shown in FIG. 8, the adhesion layer 4 can be provided in the 1st polarizer side main surface for the purpose of bonding with an image display apparatus, etc.

  The exposed surface of the pressure-sensitive adhesive layer is preferably covered with a separator for the purpose of preventing contamination until it is practically used. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foamed sheet, metal foil, laminate thereof, or the like, silicone-based or long-chain alkyl-based, fluorine-based An appropriate material according to the prior art, such as those coated with an appropriate release agent such as molybdenum sulfide or molybdenum sulfide, can be used.

  Furthermore, it can replace with the protective film 12 of FIG. 8, and can also provide optical compensation films 15, such as a phase difference film and a viewing angle compensation film, as a protective film so that it may illustrate in FIG. Further, as illustrated in FIG. 10, the optical compensation film 15 may be bonded to the protective film 12 using the adhesive layer 4 or the like separately. In particular, in a viewing angle control system used in a liquid crystal display device for mobile use that is strongly required to be thin and light, as shown in FIG. 9, an optical compensation film 15 such as a retardation film or a viewing angle compensation film is provided as a protective film. Is preferred.

  Examples of the retardation film include a film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, a liquid crystal polymer alignment layer supported by a film, and the like. The thickness of the retardation film is not particularly limited, but is generally about 20 to 150 μm.

  As said polymeric material, the thing similar to the material which comprises the said protective film can be used suitably, for example. These polymer materials can be made into an oriented product (stretched film) by molding, stretching or the like. Moreover, what supported the orientation layer of the liquid crystal polymer with the film etc. can also be used.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystal polymer include a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility, such as a nematic alignment polyester-based liquid crystal polymer, a discotic liquid crystal polymer, a cholesteric liquid crystal polymer, etc. Is mentioned. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. The thing etc. which have a mesogen part which consists of a cyclic compound unit are mentioned. These liquid crystal polymers, for example, develop a solution of a liquid crystal polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. Then, the heat treatment is performed.

  The retardation film may have an appropriate retardation according to the purpose of use, such as for the purpose of compensating for coloring or viewing angle due to birefringence of various wave plates and liquid crystal layers, for example. What laminated | stacked retardation film and controlled optical characteristics, such as phase difference, etc. may be used.

  The retardation film has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially equal.

  For example, in a retardation film satisfying nx> ny> nz, a film having a front phase difference of 40 to 100 nm, a thickness direction retardation of 100 to 320 nm, and NZ of 1.8 to 4.5 is used. preferable. For example, in a retardation film (positive A plate) that satisfies nx> ny = nz, it is preferable to use a film that satisfies a front retardation of 100 to 200 nm. For example, in a retardation film (negative A plate) that satisfies nz = nx> ny, it is preferable to use a film that satisfies a front retardation of 100 to 200 nm. For example, in the case of a retardation film satisfying nx> nz> ny, it is preferable to use a film having a front retardation of 150 to 300 nm and NZ exceeding 0 and satisfying 0.7 or less. Further, as described above, for example, nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used. The retardation film can be appropriately selected according to the type of the image display device to be applied. It can select suitably according to a liquid crystal display device.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a viewing angle compensation film include an alignment film such as a retardation film and a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation film uses a birefringent polymer film stretched uniaxially in the plane direction, whereas a retardation film used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as a polymer having a birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, and a tilted orientation film Used. Examples of the inclined alignment film include a film obtained by bonding a heat-shrinkable film to a polymer film and stretching and / or shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned.

  In addition, an optical compensation film in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystalline polymer, is supported by a triacetyl cellulose film in order to achieve a wide viewing angle with good visibility. It can be preferably used.

  The “viewing angle compensation film” as used herein suppresses a change in image quality accompanying a change in viewing direction, mainly uses a birefringence phenomenon, and the viewing angle control system of the present invention that suppresses the amount of light. The visual angle control principle is different. Therefore, the function of the viewing angle control system of the present invention is not hindered by the viewing angle compensation film.

  By arranging the viewing angle control system of the present invention on at least one main surface of the display panel, an image display device with a controlled viewing angle can be obtained. The display panel is not particularly limited. A display panel using an external light source such as a liquid crystal display (LCD), a self-luminous type such as an EL display (ELD) plasma display (PDP), or a cathode ray tube (CRT). It can be used for any display device. From the viewpoint of viewing angle control, in the case of LCD, it is preferable to arrange the viewing angle control system of the present invention on at least one main surface on the viewing side of the liquid crystal cell and the light source side. It is preferable to arrange the viewing angle control system of the present invention on the viewing-side main surface of the display panel.

  In the image display device of the present invention, as described above, the viewing angle in the direction perpendicular to the absorption axis of the first polarizer of the viewing angle control system is controlled. For example, by arranging the absorption axis of the first polarizer of the viewing angle control system of the present invention in the horizontal direction of the screen, the vertical viewing angle is controlled, and by arranging it in the vertical direction of the screen, the viewing angle in the horizontal direction can be increased. Can be controlled. These viewing angle control directions are selected based on the use of the display device. For example, in the case of an image display device arranged on a dashboard of an automobile, such as a car navigation system, it is desirable to limit the viewing angle in the vertical direction from the viewpoint of suppressing reflection on the front window. It is preferable to arrange the polarizer so that the absorption axis is equal to the horizontal direction (left-right direction) of the screen.

  In addition, in the case of ATM, it is desirable to limit the viewing angle in the left-right direction in order to prevent others from peeping, so the absorption axis of the first polarizer is arranged to be equal to the vertical direction (vertical direction) of the screen. It is preferable to do. Furthermore, in the case of ATM, in addition to looking from the left and right, it may be desired to limit the viewing angle in the upward direction, assuming the possibility that information is read by a hidden camera installed above. is there. On the other hand, it is desirable that image information can be read from below in order to make it available to a user who views the screen from below, such as a person in a wheelchair. In such a case, by using a viewing angle control system in which the absorption axis is tilted from the normal direction of the film surface as the second polarizer, the downward visibility is good and the image display that limits the upward viewing angle is performed. A device can be obtained.

  In the image display device of the present invention, the first polarizer of the viewing angle control system may also have a function of a polarizer provided for displaying the display panel or providing an antireflection function. Such a configuration is advantageous in terms of cost in addition to reducing the number of members and reducing the thickness and weight of the image display device as compared with the case where both are provided separately. Furthermore, since loss due to light absorption can be suppressed, it is advantageous in terms of screen brightness, so mobile applications and in-vehicle use where weight and thickness must be made as small as possible and power consumption must be reduced. Suitable for use.

  In the image display device of the present invention, the viewing angle control system and the display panel may be bonded and integrated, or may be arranged separately. Moreover, only the 1st polarizer of a viewing angle control system may be bonded and integrated with the display panel, and the 2nd polarizer may be arrange | positioned separately. In the case where the viewing angle control system and the display panel are used separately, the viewing angle control system can be used by being bonded to another transparent film or substrate.

  From the viewpoint of suppressing image non-uniformity due to unevenness caused by film shrinkage, the first polarizer and the second polarizer of the viewing angle control system are bonded and integrated, and further, the viewing angle control system and It is preferable that the display panel is bonded and integrated. On the other hand, by arranging separately, the viewing angle control system can be attached and detached, and the viewing angle can be controlled using the viewing angle control system only when necessary.

  The image display device of the present invention has a transparent plate on at least one main surface of a display panel, and the transparent plate and the viewing angle control system are bonded and integrated through an adhesive layer or an adhesive layer. It may be. Further, the viewing angle control system bonded and integrated with the transparent plate may be further bonded and integrated with the display panel.

  As the transparent plate, a transparent film, a sheet, or the like can be used. For example, the front plate of the image display device may also serve as a protective plate for a display or a touch screen. In such a configuration, the viewing angle control system may be bonded to the main surface on either side of the front plate, but from the viewpoint of preventing scratches, the viewing angle control system is disposed between the front plate and the display panel. It is preferable to arrange | position.

  As an example of the image display device of the present invention that is not self-luminous, an embodiment in the case of a liquid crystal display device (LCD) will be described. As described above, in the case of an LCD, it is preferable to arrange the viewing angle control system of the present invention on at least one main surface of the viewing side and the light source side of the liquid crystal cell. By the way, liquid crystal panels have various irregular materials such as TFT materials, color filters, anti-glare layers, etc., and light is refracted, reflected, diffracted and scattered at the interface of the materials, so that light is transmitted through the display panel. Propagation direction is easy to change. For this reason, when the viewing angle control system is arranged on the light source side (opposite to the viewing side) main surface, the viewing angle control effect tends to be smaller than when the viewing angle control system is arranged on the viewing side main surface. From this viewpoint, in order to perform the viewing angle control more efficiently, it is preferable that the viewing angle control system 100 is disposed on the viewing-side main surface of the display panel (liquid crystal cell) 300 as shown in FIG.

  In addition, as shown in FIG. 13, viewing angle control systems 100 a and 100 b can be provided on both main surfaces of the display panel (liquid crystal cell) 300. In FIG. 13, the viewing angle control systems 100a and 100b are illustrated such that the absorption axis directions of the first polarizers are parallel to each other, but the viewing angle control is performed by arranging both in parallel in this way. It is possible to control the change of the viewing angle control characteristic in the direction, that is, in the direction perpendicular to the absorption axis direction of the first polarizer. On the other hand, by arranging the absorption axis directions of the first polarizers of the viewing angle control systems 100a and 100b so as to be vertical, the vertical, horizontal, and horizontal viewing angles can be controlled simultaneously.

  As described above, in order for the first polarizer of the viewing angle control system to have the function of the polarizer of the liquid crystal panel, the viewing angle control system has a liquid crystal on the first polarizer side main surface as shown in FIGS. It is preferable to be arranged so as to be on the cell 300 side.

  The liquid crystal display device can be formed according to the conventional method. In other words, a liquid crystal display device is generally formed by assembling a liquid crystal cell, a polarizing plate or an optical film, and components such as a light source as necessary and incorporating a drive circuit.

  The type of the liquid crystal cell is not particularly limited, and is twisted nematic (TN) mode, super twisted nematic (STN) mode, horizontal alignment (ECB) mode, vertical alignment (VA) mode, in-plane switching (IPS) mode, fringe field. Various liquid crystal cells such as switching (FFS) mode, bend nematic (OCB) mode, hybrid alignment (HAN) mode, ferroelectric liquid crystal (SSFLC) mode, and antiferroelectric liquid crystal (AFLC) mode liquid crystal cells may be used. it can. In particular, in the image display device of the present invention, since the purpose is usually to control the viewing angle in the vertical or horizontal direction, it is common to arrange the absorption axis of the display polarizer parallel or perpendicular to the horizontal direction of the screen. A mode or IPS mode liquid crystal cell can be preferably used.

  As the light source, for example, a sidelight type backlight using a light source 401 and a light guide plate 404 arranged on the side as shown in FIG. 11, or a light source arranged directly under the liquid crystal cell 300 as shown in FIG. A direct type backlight provided with 401, a planar light source, or the like can be used. Further, a prism sheet 402, a diffusion plate 403, a reflection plate 405, or the like may be provided. The prism sheet collects light emitted in either the upper or lower direction or the left or right direction based on its shape, thereby improving the luminance in a predetermined direction. Since the light is collected in a predetermined direction, the luminance in the other direction is decreased, and as a result, the viewing angle in that direction is narrowed. However, in the image display device of the present invention, the luminance is decreased by the prism sheet. By substantially matching the direction and the direction in which the viewing angle is controlled by the viewing angle control system, the viewing angle can be controlled more effectively while improving the luminance in the main transmission direction.

  In forming a liquid crystal display device, in addition to the above, appropriate components such as an antireflection film, a protective plate, a lens sheet, and a light scattering plate can be arranged in one or more layers at appropriate positions.

  Furthermore, in the liquid crystal display device of the present invention, a member such as an optical compensation film can be provided. As the optical compensation film, those described above as those used in the viewing angle control system can be suitably used.

  Next, a case where the display panel is a self-luminous type such as ELD, PDP, or CRT will be described. In the self-luminous display device, it is preferable that the viewing angle control system is disposed on the viewing side of the display panel for viewing angle control. Moreover, you may arrange | position so that the main surface of the 1st polarizer side of the viewing angle control system and the 2nd polarizer side may become a display panel side.

  In particular, in the case of an ELD in which the reflection of external light from the electrode reduces visibility, or a PDP in which the light emitter causes irregular reflection, the circularly polarizing plate can prevent reflection, but as shown in FIG. A circular polarization means 5 is disposed between the first polarizer 1 and the self-luminous display panel 500 so as to convert linearly polarized light into substantially circularly polarized light. By providing, the 1st polarizer of a viewing angle control system can have the function of the polarizer for reflection prevention of a liquid crystal panel.

  Here, the substantially circularly polarized light can include not only a completely circularly polarized state but also elliptically polarized light, but the ellipticity is preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.8. That's it. The circularly polarizing means is not particularly limited as long as it converts linearly polarized light into the above substantially circularly polarized light at any wavelength of visible light. Preferably, the linearly polarized light is converted into the above substantially circular shape at a wavelength of 550 nm. It is preferable to convert it into polarized light.

  A typical example of the circular polarization means is a retardation film having a retardation in the range of about ¼ wavelength of visible light when viewed from the normal direction of the film surface. Examples thereof include an arrangement in which the angle formed between the phase axis and the absorption axis of the first polarizer is about 45 °. The quarter wavelength and about 45 ° are not particularly limited as long as they can be converted into the aforementioned substantially circularly polarized light, but the phase difference is preferably within a range of ± 30 nm of the quarter wavelength. A range of 20 nm is more preferable, and a range of ± 10 nm is more preferable. The angle is preferably in the range of 45 ° ± 10 °, more preferably in the range of ± 5 °, and further preferably in the range of ± 3 °.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

The front phase difference (Re) and the thickness direction phase difference (Rth) were determined as follows.

  Using an automatic birefringence meter (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA-21ADH), the front direction at a measurement wave of 550 nm and the phase difference when the film is tilted 40 ° about the slow axis center are measured. From these values, refractive indexes nx, ny, and nz were calculated in the direction in which the in-plane refractive index was maximum, the direction perpendicular thereto, and the thickness direction of the film. From these values and thickness (d), front phase difference: (nx−ny) × d and thickness direction phase difference: (nx−nz) × d were determined.

(Production Example 1)
As an additive for improving the vertical alignment with respect to 100 parts by weight of a monofunctional thermotropic cyanobiphenyl nematic liquid crystal monomer having a polymerizable group at the terminal, a polymer liquid crystal represented by the following chemical formula (black gold) 25 parts by weight made by Kasei Co., copolymerization ratio: n = 35), 400 parts by weight 4-methyl-2-pentanone (MIBK) as a solvent, and 5 polymerization initiators (Irgacure 907 made by Ciba Specialty Chemicals) A part by weight was added and mixed and dissolved to prepare a liquid crystal composition solution. Also, 100 parts by weight of cyclopentanone, 1.5 parts by weight of a polyazo dye having an absorption peak at a wavelength of 458 nm, 0.8 parts by weight of a polyazo dye having an absorption peak at a wavelength of 542 nm, and an absorption peak at a wavelength of 621 nm A dye solution was prepared by dissolving 1 part by weight of a polyazo dye having NO. The liquid crystal composition solution and the dye solution mixed at a weight ratio of 4: 1 are applied to an unstretched amorphous polyolefin film (Zeonor film, thickness 100 μm, manufactured by Optes) and heated at 50 ° C. The solvent was evaporated to form a liquid crystal / BR> cM mer layer. This is further heated at 80 ° C. to make the liquid crystal monomer layer isotropic, and then slowly cooled and irradiated with 300 mJ / m ² of ultraviolet light while applying a 1 kV DC electric field in the normal direction of the film surface. Thus, the liquid crystal monomer was polymerized and completely cured to produce a polarizer having an absorption axis in the normal direction of the film surface. The thickness of the obtained polarizer was 3 μm. A polarizing plate A was prepared by pasting a triacetyl cellulose (TAC) film (Z-TAC, manufactured by Fuji Film Co., Ltd., thickness 80 μm) on both surfaces of this polarizer using a polyvinyl alcohol-based adhesive. In addition, the front phase difference of the TAC film used at this time was 1 nm, and the thickness direction phase difference was 3 nm.

(Production Example 2)
The absorption axis is set at an angle that is neither perpendicular nor parallel to the normal to the film surface in the same manner as in Production Example 1 except that the direction of the DC electric field applied during UV irradiation is inclined by 20 ° with respect to the normal direction of the film surface. The polarizer which has was produced and the TAC film was bonded on both surfaces of the polarizer similarly to the manufacture example 1, and the polarizing plate B was produced.

Example 1
(Creation of viewing angle control system)
An iodine-based polarizing plate (SIG 1463DU manufactured by Nitto Denko Corporation, hereinafter referred to as “polarizing plate C”) having an absorption axis in the film plane is provided on one main surface of the polarizing plate A prepared in Production Example 1. The viewing angle control system D was produced by bonding using an adhesive.

(Production of image display device)
The viewing side polarizing plate and the light source side polarizing plate are arranged in crossed Nicols, the light source side polarizing plate is provided with a biaxial (nx>ny> nz) retardation film, and the viewing side polarizing plate is an optical compensation film. The viewing-side polarizing plate of the VA mode liquid crystal display device (Sharp AQUAS) that is not provided is peeled off, and the viewing angle control system D is replaced with the polarizing plate C on the liquid crystal cell side instead of the viewing-side polarizing plate. And an acrylic pressure-sensitive adhesive to obtain an image display device. When the viewing angle control system D was bonded, the direction of the absorption axis of the polarizing plate C was matched with the direction of the absorption axis of the polarizing plate before peeling.

(Example 2)
(Creation of viewing angle control system)
On one main surface of the polarizing plate B produced in Production Example 2, the polarizing plate C is 90 °, and the angle formed between the normal line of the main surface of the polarizing plate B and the absorption axis of the polarizing plate C is 90 °. In this way, the viewing angle control system E was created by bonding using an acrylic pressure-sensitive adhesive.

(Production of image display device)
An image display apparatus was obtained in the same manner as in Example 1 except that the viewing angle control system E was used instead of the viewing angle control system D. In addition, when bonding the viewing angle control system E, the electric field direction (that is, the absorption axis direction of the polarizing plate B) in Production Example 2 was arranged so as to be the screen lower direction on the viewing side.

(Comparative Example 1)
(Production of image display device)
An image display apparatus was obtained in the same manner as in Example 1 except that the polarizing plate C was used in place of the viewing angle control system D.

(Evaluation test)
The viewing angle characteristics (luminance viewing angle dependency) when the image display devices obtained in Examples and Comparative Examples were set to the white display state were evaluated using a conoscope. The results are shown in FIG. In each of (a) to (c) of FIG. 15, the outermost curve represented by a thick line represents an isoluminance curve with a luminance of 50 cd / m ² .

When evaluating the viewing angle control performed at equal brightness curve of the luminance 50 cd / ^{m 2} Examples and Comparative Examples, in Comparative Example 1 (c) of FIG. 15, range of the luminance 50 cd / ^{m 2,} the upper and lower (90 ° - 270 °) and left and right (0 ° -180 °) directions were 75 °. In other words, when a polarizing plate that is not subjected to viewing angle control as in Comparative Example 1 is used, information on the screen can be viewed in all directions, and there is a high risk of being looked into from others.

On the other hand, in Example 1 of FIG. 15A, the range in which the luminance is 50 cd / m ² is 75 ° in the left-right direction as in Comparative Example 1, but is 45 in the vertical direction. °. That is, it can be seen that the light in the left-right direction is not limited, whereas the light in the vertical direction has a limited emission angle and is controlled in viewing angle. Further, in Example 2 of FIG. 15B, the range in which the luminance is 50 cd / m ² is 70 ° in the left-right direction, which is substantially the same as Comparative Example 1 and Example 1, but is 25 ° upward. In the downward direction, 65 [deg.] Is asymmetrical in the vertical direction. Thus, it can be seen that the upward emission of light can be restricted by using a polarizer having an inclined absorption axis.

The maximum brightness in Comparative Example 1, 515cd / ^{m 2} in the front direction, 450 cd / ^{m 2} in the front direction in the first embodiment, a 385cd / ^{m 2} in the lower 25 ° direction in the second embodiment, the present invention Even when viewing angle control is performed by the viewing angle control system, the decrease in white luminance in the direction in which the viewing angle should be maintained is small, and the visibility of the screen can be maintained.

  As described above, it can be seen that the viewing angle control system according to the present invention can impart directivity to an invisible region with low luminance, and achieve viewing angle control. In the state where the viewing angle control is not performed, the vertical and horizontal viewing angles of the VA liquid crystal panel used in the example are approximately equal every 90 ° as shown in Comparative Example 1. Accordingly, by rotating the direction of the display device by 90 °, the viewing angle control in the left-right direction can be achieved as in the above-described embodiment.

DESCRIPTION OF SYMBOLS 1 1st polarizer 1a Absorption axis 2 2nd polarizer 2a Absorption axis 3 Adhesive layer 4 Adhesive layer 5 Circular polarization means 11 Protective film 12 Protective film 14 Adhesive layer 15 Optical compensation film 21 Protective film 22 Protective film 23 Surface treatment layer 30 medium 100 viewing angle control system 100a viewing angle control system 100b viewing angle control system 200 structural unit of light control film 201 translucent layer 202 louver 203 protective layer 300 liquid crystal cell 301 polarizing plate 400 backlight system 401 light source 402 prism sheet 403 diffuser plate 404 Light plate 405 Reflector 500 Self-luminous display panel

Claims (18)

Having a first polarizer and a second polarizer in the form of a film containing an absorbing dichroic substance having a fixed orientation;
The first polarizer has an absorption axis in the film plane,
In the second polarizer, the absorption axis is inclined from the normal direction of the film surface, the angle formed by the absorption axis and the normal line of the film surface is 45 ° or less , and the film surface of the second polarizer is A viewing angle control system in which an angle formed by a plane including a normal line and an absorption axis and the absorption axis of the first polarizer is substantially perpendicular.   The viewing angle control system according to claim 1, wherein an angle formed by a plane including a normal line of the film surface of the second polarizer and an absorption axis and an absorption axis of the first polarizer is 90 ° ± 5 °. .   A medium is provided between the first polarizer and the second polarizer, and the medium does not substantially convert the polarization state of light in the normal direction of the film surface of the second polarizer. The viewing angle control system according to claim 1 or 2.   The viewing angle control system according to claim 3, wherein an in-plane phase difference of the medium between the first polarizer and the second polarizer is 40 nm or less.   The viewing angle control system according to claim 3 or 4, wherein a slow axis of a medium between the first polarizer and the second polarizer is parallel or perpendicular to an absorption axis of the first polarizer.   The viewing angle control system according to any one of claims 1 to 5, wherein a phase difference in a thickness direction of the medium between the first polarizer and the second polarizer is 60 nm or less.   The viewing angle control system according to any one of claims 1 to 6, wherein the first polarizer and the second polarizer are bonded and integrated through an adhesive layer and / or an adhesive layer.   The viewing angle control system according to any one of claims 1 to 7, further comprising an adhesive layer on at least one of the first polarizer-side main surface and the second polarizer-side main surface.   An image display device in which the viewing angle control system according to claim 1 is arranged on at least one main surface of a display panel.   The image display device according to claim 9, wherein the first polarizer side main surface of the viewing angle control system is disposed on the display panel side.   The image display device according to claim 9 or 10, wherein the display panel and the viewing angle control system are bonded and integrated through an adhesive layer and / or an adhesive layer.   A transparent plate is provided on at least one main surface of the display panel, and the transparent plate and the viewing angle control system have an adhesive layer and / or an adhesive so that the second polarizer main surface side is the display panel side. The image display device according to any one of claims 9 to 11, wherein the image display device is disposed by being bonded and integrated through a layer.   The image display device according to claim 9, wherein a viewing angle limiting direction of the display device is perpendicular to an absorption axis direction of the first polarizer.   The image display device according to claim 9, wherein the display panel is a liquid crystal panel having a polarizer on at least one main surface of a liquid crystal cell, and the polarizer also serves as a first polarizer of the viewing angle control system.   The display panel is a liquid crystal panel having a polarizer on at least one main surface of the liquid crystal cell, has a light source on one side of the liquid crystal panel, and emits light between the light source and the liquid crystal panel. A prism sheet that condenses light in one direction, and the viewing angle limiting direction that is perpendicular to the absorption axis direction of the first polarizer is substantially parallel to the direction in which luminance decreases due to light condensing by the prism sheet. Or the display apparatus of 14.   The viewing angle control system according to any one of claims 1 to 8 is disposed on both main surfaces of the display panel, and the absorption axis direction of the first polarizer of the visual control system on one main surface side of the display panel; The image display device according to claim 9, wherein an absorption axis direction of the first polarizer of the visual control system on the other main surface side of the display panel is substantially parallel or substantially perpendicular.   The image display device according to claim 9, wherein the display panel is a self-luminous display device, and the viewing angle control system is disposed on a viewing side of the display panel.   The image display apparatus according to claim 17, further comprising a circular polarization unit configured to convert linearly polarized light into substantially circularly polarized light between the first polarizer of the viewing angle control system and the display panel.

Images