JP2007003626A - Reflective polarizer, method and device for manufacturing same and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflective polarizer excellent in weather resistance and uniformity. <P>SOLUTION: Inorganic material 110 evaporated from a crucible 109 is made incident from the oblique direction with respect to the principal surface of a transparent support 31 which is made to run by a cooling can 108. Inorganic material 115 evaporated from a crucible 114 is made incident from the vertical direction with respect to the principal surface of the transparent support 31. Thereby, an optically isotropic thin film having a columnar structure vertical to the principal surface of the transparent support 31 and an optically anisotropic thin film having a columnar structure inclined to the principal surface of the transparent support can be alternately laminated on the transparent support 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reflective polarizer that controls the vibration direction of light, a method for manufacturing the same, a manufacturing apparatus for the reflective polarizer, and a liquid crystal display device including the reflective polarizer.

  In a liquid crystal display (LCD), a polarizer is an indispensable important member. Conventionally, as this polarizer, one that exhibits absorption dichroism in which one polarization component of light is absorbed and the other polarization component is transmitted is generally used. In this type of polarizer, 50% of light is absorbed in principle to obtain linearly polarized light, and half of the input light is lost as heat energy. The light absorption by the polarizer is a main factor of the poor light utilization efficiency of the liquid crystal display device.

  In view of this, a reflective polarizer has been proposed for the purpose of increasing the light utilization efficiency. This reflective polarizer is provided between the liquid crystal panel and the backlight, passes only one of the orthogonally polarized components of the light emitted from the backlight, reflects the other, and re-enters the backlight. Then, the light is again incident on the reflective polarizer by diffuse reflection. By repeating this reflection, the light that is originally absorbed can be recycled to improve the luminance of the liquid crystal display device.

  In recent years, as the reflective polarizer, those utilizing the birefringence of a stretched resin film have been widely used (see, for example, Patent Document 1). This reflective polarizer is formed by alternately laminating optically anisotropic films and optically isotropic films. The optically anisotropic film can be obtained by drawing a crystalline naphthalenedicarboxylic acid ester such as polyethylene naphthalate (PEN) into a film by a melt extrusion method and then stretching it. The optically isotropic form can be obtained by drawing a naphthalenedicarboxylic acid and a copolyester of terephthalic acid or isotalic acid (coPEN) into a film by melt extrusion and then stretching.

Japanese Patent No. 3448626

  However, this polymer thin film reflective polarizer has a problem in poor weather resistance such as ultraviolet ray degradation and heat deformation peculiar to organic substances. Moreover, since it is produced by the melt extrusion method and stretching, it is difficult to control the thickness of each layer of the polymer thin film on the nano order, and there is a problem that the uniformity is poor.

  Accordingly, an object of the present invention is to provide a reflective polarizer excellent in weather resistance and uniformity, a method for manufacturing the same, a manufacturing apparatus for the reflective polarizer, and a liquid crystal display device including the reflective polarizer.

In order to solve the above-mentioned problem, the first invention is an inorganic thin film having optical anisotropy and an inorganic thin film having optical isotropy alternately laminated on a transparent support,
An inorganic thin film having optical anisotropy and an optical thin film having optical isotropy have the same refractive index in one polarization direction of incident light, and different refractive indexes in the other polarization direction orthogonal to one polarization direction. It is a reflective polarizer characterized by having.

  According to the first invention, the inorganic thin film having optical anisotropy and the inorganic thin film having optical isotropy have no refractive index difference in one polarization direction of incident light and are orthogonal to one polarization direction. Since there is a difference in refractive index in the other polarization direction, one polarization component of incident light is transmitted, while the other polarization component can be reflected.

  In the first invention, the birefringence (Δn) of the inorganic thin film having optical anisotropy is preferably 0.03 or more. The inorganic thin film having optical anisotropy has a columnar structure inclined with respect to the main surface of the transparent support, and the inorganic thin film having optical isotropy is perpendicular to the main surface of the transparent support. It is preferable to have a columnar structure, periodically repeat the columnar structure in the in-plane direction, and make the interval between the columnar structures narrower than the wavelength of visible light. Further, the columnar structure of the inorganic thin film having optical anisotropy is preferably tilted by 5 degrees or more and 85 degrees or less toward the other polarization direction with respect to the normal line of the main surface of the transparent support. Moreover, it is preferable that the diameter of the columnar structure of the inorganic thin film having optical anisotropy is 100 nm or less.

According to a second aspect of the present invention, there is provided a step of forming an optically anisotropic film by causing an inorganic material to be incident on the main surface of the transparent support from an oblique direction with the first vaporization source, and an inorganic material with the second vaporization source. Forming an optically isotropic film by making the light incident from a direction perpendicular to the main surface of the transparent support;
Is a method for producing a reflective polarizer, characterized in that is alternately repeated.

  According to the second invention, the step of growing the inorganic material in a direction oblique to the main surface of the transparent support, and the step of growing the inorganic material in a direction perpendicular to the main surface of the transparent support. Since it can be repeated alternately, an optically anisotropic film made of an inorganic material and an optically isotropic film made of an inorganic material can be alternately laminated on the transparent support.

  In the second invention, in the step of forming the optically anisotropic film, the angle formed by the normal direction of the main surface of the transparent support and the incident direction of the inorganic material is preferably 95 degrees or more and 175 degrees or less.

  In the second invention, the step of forming the optically anisotropic film and the optical isotropy by running the transparent support so as to periodically pass over the first vaporization source and the second vaporization source. It is preferable to repeat the process of forming a film alternately.

  The second invention is preferably applied to thin film manufacturing methods such as sputtering, chemical vapor deposition, vacuum deposition, and ion plating.

The third invention is a traveling means for traveling the transparent support;
A first vaporization source for injecting an inorganic material from an oblique direction with respect to the transparent support traveled by the travel means;
A second vaporization source for allowing the inorganic material to enter from a direction perpendicular to the transparent support traveled by the travel means,
A traveling polarizer travels a transparent support so that the transparent support periodically passes over the first vaporization source and the second vaporization source.

  According to the third invention, the inorganic material is grown in an oblique direction with respect to the main surface of the transparent support traveled by the travel means, and is perpendicular to the main surface of the transparent support traveled by the travel means. Since the inorganic material is grown in the direction, the optically anisotropic film made of the inorganic material and the optically isotropic film made of the inorganic material can be alternately laminated on the transparent support.

  In the third invention, the first vaporization source may be provided such that an angle formed between the normal direction of the main surface of the transparent support and the incident direction of the inorganic material is 95 degrees or more and 175 degrees or less. preferable.

  The third invention is preferably applied to an apparatus using a vacuum thin film production technique such as sputtering, chemical vapor deposition, vacuum deposition, and ion plating.

  In the third aspect of the invention, it is preferable that the first vaporization source is provided to be inclined with respect to the main surface of the support, and the second vaporization source is provided in parallel to the main surface of the support.

  As described above, according to the present invention, the reflective polarizer is formed by laminating an inorganic thin film made of an inorganic material, so that it is possible to suppress ultraviolet deterioration and thermal deformation. Therefore, it is possible to provide a reflective polarizer having excellent weather resistance.

  In addition, the reflective polarizer is made by making an inorganic material incident on the transparent support and alternately laminating optically anisotropic films and optically isotropic films, so the thickness of the reflective polarizer is controlled in nano-order. can do. Therefore, it is possible to provide a reflective polarizer having excellent uniformity.

An embodiment of the present invention will be described in the following order.
(1) Configuration of liquid crystal display device (2) Configuration of reflective polarizer (3) Configuration of reflective polarizer manufacturing device (4) Method of manufacturing reflective polarizer

(1) Configuration of Liquid Crystal Display Device FIG. 1 is a cross-sectional view showing a configuration example of a liquid crystal display device 1 according to an embodiment of the present invention.
Hereinafter, the configuration of the liquid crystal display device 1 will be described with reference to FIG.

  As shown in FIG. 1, the liquid crystal display device 1 is a so-called transmissive liquid crystal display device, and includes a liquid crystal panel 2 and a backlight 7 as a light source. In the following, the side that becomes the display screen of the liquid crystal display device 1 is referred to as a display surface side, and the opposite side is referred to as a back side.

  The backlight 7 is, for example, a cold cathode fluorescent lamp (CCFL) or an LED (Light Emitting Diode), and is disposed immediately below the liquid crystal panel 2. Here, an example of a method of arranging the backlight 7 directly under the liquid crystal panel 2 (directly under type) is shown, but the method of the backlight is not limited to this example, and one end side (edge) of the liquid crystal panel 2 is shown. A backlight (7) such as a cold cathode tube or an LED may be disposed on the side), and a method (edge type) in which light from the backlight 7 is spread over the entire surface of the liquid crystal panel 2 through a light guide plate. In addition, when the liquid crystal panel 2 is a large-sized liquid crystal panel for television use or the like, the backlight is preferably a direct type.

  The liquid crystal panel 2 is formed by sealing liquid crystal between the first substrate 3 and the second substrate 4 and the first substrate 3 and the second substrate 4 that are opposed to each other with a spacer 5 spaced apart from each other. A liquid crystal layer 6. The spacer 5 is for maintaining a predetermined distance between the first substrate 3 and the second substrate 4. The liquid crystal layer 6 is made of, for example, a liquid crystal such as a nematic liquid crystal, and its arrangement changes according to the voltage applied between the first substrate 3 and the second substrate 4.

  The first substrate 3 is a semiconductor element substrate such as a TFT (Thin Film Transistor) substrate. The first substrate 3 includes a substrate 21 made of glass, plastic, or the like. A transparent electrode 22 and an alignment film 23 are sequentially stacked on one main surface of the substrate 21, and a reflective polarizer is formed on the other main surface. 24 are laminated. Although illustration is omitted for convenience, a semiconductor element such as a TFT, a signal line, and a scanning line are provided on one main surface of the substrate 21.

  The second substrate 4 is a color filter substrate (CF substrate). The second substrate 4 includes a substrate 11. A color filter 12, a transparent electrode 13, and an alignment film 14 are sequentially stacked on one main surface of the substrate 11. A polarizer is formed on the other main surface of the substrate 11. 15 are stacked.

  The transparent electrodes 13 and 22 are, for example, an alloy oxide (ITO: Indium Tin Oxide) of indium and tin. The alignment films 14 and 23 are films for aligning liquid crystal molecules in a certain direction, and are made of a polymer such as polyimide, for example.

  The color filter 12 is for color display. For example, R (red), G (green), and B (blue) elements are arranged corresponding to the pixels. Each pixel is composed of three sub-pixels of R (red), G (green), and B (blue). The size of the sub-pixel depends on the screen size and the number of pixels, but is about several tens of μm, for example.

  The polarizer 15 allows only one of orthogonally polarized components of incident light to pass through and blocks the other by absorption. The reflective polarizer 24 allows only one of the orthogonal polarization components of incident light to pass and reflects the other. For example, the polarizer 15 and the reflective polarizer 24 are provided so that their transmission axes are orthogonal to each other. The reflective polarizer 24 can also be installed between a conventional liquid crystal panel and a backlight and used as a brightness enhancement film. That is, a conventional polarizer is used in place of the reflective polarizer 24, and the reflective polarizer 24 is installed between the liquid crystal panel and the backlight. The polarizer and the reflective polarizer 24 are provided so that their transmission axes are parallel to each other.

(2) Configuration of Reflective Polarizer FIG. 2 is a cross-sectional view showing a configuration example of the reflective polarizer 24 according to one embodiment of the present invention. In FIG. 2, n _1x and n _1y indicate the refractive index in the x-axis direction and the refractive index in the y-axis direction of the optically anisotropic film 32, respectively. N _2x and n _2y represent the refractive index in the x-axis direction and the refractive index in the y-axis direction of the optical isotropic film 33, respectively.

  As shown in FIG. 2, the reflective polarizer 24 is formed by alternately laminating optical anisotropic films 32 and optical isotropic films 33 on a support 31. The reflection polarizer 24 reflects a polarization component parallel to the x-axis (x-polarization component in FIG. 2) of the light L incident on the reflection polarizer 24, whereas the polarization component is parallel to the y-axis. (Y polarization component in FIG. 2) is transmitted. Hereinafter, in the support 31, one main surface on the side where the optical anisotropic film 32 and the optical isotropic film 33 are laminated is referred to as a film formation surface.

  The support 31 is a transparent substrate or film. As the material of the support 31, transparent glass or plastic can be used. As the glass, for example, soda lime glass, lead glass, hard glass, quartz glass, or liquid crystallized glass can be used. As the plastic, for example, polycarbonate, polyolefin, acrylic resin, or the like can be used.

  The optically anisotropic film 32 has different refractive indexes, that is, birefringence in the x-axis direction and the y-axis direction. On the other hand, the optical isotropic film 33 has the same refractive index in the x-axis direction and the y-axis direction.

Unlike the refractive index n _{1x in} the x-axis direction of the optical anisotropic film 32 and the refractive index n _{2x in} the x-axis direction of the optical isotropic film 33, the optical anisotropic film 32 and the optical isotropic film 33 are different from each other. There is a refractive index difference between the films in the x-axis direction. This refractive index difference is preferably 0.03 or more. If the number is less than 0.03, the number of layers of the optically anisotropic film 32 and the optically isotropic film 33 exceeds 300 in order to satisfy the characteristics as a reflective polarizer. Invite to rise. On the other hand, the refractive index n _{1y in} the y-axis direction of the optical anisotropic film 32 and the refractive index n _{2y in} the y-axis direction of the optical isotropic film 33 are equal, and the optical anisotropic film 32 and the optical isotropic film 33 are equal. There is no difference in refractive index between the two films in the y-axis direction.

That is, the refractive indices n _1x and n _{2x in} the x direction and the refractive indices n _1y and n _{2y in} the y direction of the optical anisotropic film 32 and the optical isotropic film 33 satisfy the following relationship.
n _1x <n _1y , n _2x = n _2y
n _1x <n _2x , n _1y = n _2y
Δn = n _1y −n _1x = n _2x −n _1x > 0

The optically anisotropic film 32 is formed by allowing an inorganic material to enter the film forming surface of the support 31 from an oblique direction by using a vacuum thin film forming technique. Has an inclined columnar structure. The optical isotropic film 33 is formed by allowing an inorganic material to enter from a direction perpendicular to the film formation surface of the support 31. For example, the optical isotropic film 33 has a columnar structure perpendicular to the film formation surface of the support 31. The optical anisotropic film 32 and the optical isotropic film 33 are not limited to the columnar structure. For example, when a mixture of Ta ₂ O ₅ and CeO ₂ is made to enter from a direction oblique to the film formation surface of the support 31, a columnar structure is not formed, and this mixture is granular. In this case, optical anisotropy can be obtained. That is, the optical anisotropy is obtained by forming a dense structure having a period shorter than the wavelength of light in the in-plane direction of the film, and is not necessarily limited to the columnar structure. The optical isotropic film may be a film having a uniform density in the in-plane direction.

The optical anisotropic film 32 and the optical isotropic film 33 are made of the same or different inorganic materials. When the optically anisotropic film 32 and the optically isotropic film 33 are formed of the same material, the refractive index n _{1y in} the y-axis direction of the optically anisotropic film 32 and the y-axis of the optically isotropic film 33 are The refractive index n _{2y in the} direction can be easily made equal.

Here, the optical anisotropic film 32 and the optical isotropic film 33 will be described using specific numerical values as examples. The optically anisotropic film 32 has, for example, a refractive index n _1x = 1.8 as a refractive index in the _x -axis direction and a refractive index n _1y = 2.0 as a refractive index in the y-axis direction. The optical isotropic film 33 has, for example, a refractive index n _2x = 2.0 as a refractive index in the _x -axis direction and a refractive index n _2y = 2.0 as a refractive index in the y-axis direction. In this case, there is a refractive index difference Δn = 2.0−1.8 = 0.2 between the films in the x-axis direction. On the other hand, in the y-axis direction, since the refractive index is equal between the films, the refractive index difference between the films is Δn = 2.0−2.0 = 0.0. With these optical characteristics, the multilayer laminate functions as a reflective polarizer that reflects only the x-polarized component of incident light and transmits the y-polarized component.

  The number of layers in which the optically anisotropic film 32 and the optically isotropic film 33 are laminated is defined by the value of Δn. For example, when the refractive index difference between the films is Δn = 0.03, the number of layers is 500 to 600 nm. In order to cover the Green band, the number of layers is selected to be about 300 layers. Thus, by laminating the optically anisotropic film 32 and the optically isotropic film 33, a function as a reflective polarizer can be obtained.

  The optically anisotropic film 32 and the optically isotropic film 33 are made of an inorganic material having transparency, for example, made of a dielectric having transparency, and more specifically, for example, an oxide or sulfide having transparency. Or it consists of fluoride etc.

As the oxide, for example, an oxide of tantalum (Ta), titanium (Ti), zirconium (Zr), niobium (Nb), cerium (Ce), aluminum (Al), silicon (Si), or a mixture thereof is used. More specifically, for example, tantalum pentoxide (Ta ₂ O ₅ ), trititanium pentoxide (Ti ₃ O ₅ ), dititanium trioxide (Ti ₂ O ₃ ), titanium monoxide (TiO), Titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), cerium dioxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), silicon monoxide (SiO), ZnO (zinc oxide) or a mixture thereof can be used.

As the sulfide, for example, zinc sulfide (ZnS), cadmium sulfide (CdS), or the like can be used. As the fluoride, for example, magnesium fluoride (MgF ₂ ), cerium fluoride (CeF ₃ ), barium fluoride (BaF ₂ ), calcium fluoride (CaF ₂ ), neodymium fluoride (NdF ₃ ), etc. are used. Can do.

  The optical performance of the reflective polarizer 24 is determined by the optical thickness (refractive index × thickness) of each layer. If the film has an optical thickness that is smaller than the wavelength of light, structural interference can be utilized to enhance the optical performance of the reflective polarizer 24 at the selected wavelength. As a film forming method for forming a uniform layer having an optical thickness thinner than the wavelength of light, for example, a vacuum thin film forming technique can be used. As a vacuum thin film formation technique, for example, a sputtering method, a chemical vapor deposition method, a vacuum deposition method, an ion plating method, or the like can be used.

  Specifically, the structural interference is determined by the optical thickness of the paired films (optical thickness of the optical anisotropic film + optical thickness of the optical isotropic film) of the wavelength of the incident light. Occurs when halved. This half-wavelength condition results in narrowband structural interference centered on the design wavelength λ. Broadband optical performance can be obtained by stacking multiple narrowband combinations. For example, a first group of layers having the same thickness (optical thickness of an optically anisotropic film + optical thickness of an optically isotropic film = λ / 2) may be changed to a different thickness (an optically anisotropic film). Of the optically isotropic film and the optical thickness of the optically isotropic film = λ ′ / 2), the two types of bands centering on λ and λ ′ are combined, Broadband.

For example, in order to obtain broadband optical characteristics, a first laminated body formed by laminating an optical anisotropic film 32 having a film thickness d ₁ and an optical isotropic film 33, an optical anisotropic having a film thickness d ₂ A second laminate formed by laminating the optical film 32 and the optical isotropic film 33,..., And a second laminate obtained by laminating the optical anisotropic film 32 and the optical isotropic film 33 having a film thickness d _n . The n stacked bodies are sequentially stacked on the support 31. The thickness _{d 1, d 2, ···,} d n is appropriately selected depending on the band to be desired.

More specifically, for example, in order to obtain a wide band optical properties that covers the white light emitted from the backlight 7, laminated optically anisotropic film 32 and the optically isotropic film 33 having a thickness d ₁ the first laminate, a second laminate formed by laminating the optically anisotropic film 32 and the optically isotropic film 33 having a thickness d _2, the optically anisotropic film with a thickness d ₃ which is formed by 32 and a _fourth laminated body in which an optically anisotropic film 32 having a film thickness d ₄ and an optically isotropic film 33 are laminated. It is preferable to sequentially laminate the body 31. Here, the film thicknesses d ₁ , d ₂ ,..., D ₄ are appropriately selected according to the band corresponding to white light.

  FIG. 3 is a cross-sectional view of the reflective polarizer 24 having a columnar structure in the xz plane. FIG. 4 is a cross-sectional view of the reflective polarizer 24 having a columnar structure in the yz plane. The optically anisotropic film 32 is an obliquely grown thin film, and has a columnar structure that is inclined with respect to the x axis and grown perpendicularly to the y axis. Optical anisotropy can be obtained by obliquely growing the columnar structure in this way. The columnar structure of the optically anisotropic film 32 is inclined, for example, by 5 degrees or more and 85 degrees or less in the x-axis direction with respect to the normal line (that is, the z axis) of the film formation surface of the support 31. On the other hand, the optical isotropic film 33 has a columnar structure grown perpendicular to both the x-axis and the y-axis. Optical isotropy can be obtained by growing the columnar structure in this way.

  The columnar structures of the optical anisotropic film 32 and the optical isotropic film 33 are periodically repeated in the in-plane direction, and the interval d between adjacent columnar structures is selected to be narrower than the wavelength of visible light, for example. . Further, the columnar structures of the optically anisotropic film 32 and the optically isotropic film 33 have, for example, the same diameter D, and the diameter D is, for example, 100 nm or less.

(3) Configuration of Reflective Polarizer Manufacturing Apparatus FIG. 5 is a schematic diagram showing a configuration example of a reflective polarizer manufacturing apparatus 101 according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing the positional relationship between the crucible 109 serving as the first vaporization source and the cooling can 108. FIG. 7 is a schematic cross-sectional view showing the positional relationship between the crucible 114 serving as the second vaporization source and the cooling can 108. The reflective polarizer manufacturing apparatus 101 is a vacuum vapor deposition apparatus capable of alternately laminating the optical anisotropic film 32 and the optical isotropic film 33 on the support 31.

  Hereinafter, the configuration of a reflective polarizer manufacturing apparatus 101 according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 5, the reflective polarizer manufacturing apparatus 101 includes a vacuum chamber 103, and a vacuum exhaust system 102 is provided on a side surface of the vacuum chamber 103. By this evacuation system 102, the inside of the vacuum chamber 103 is brought into a high vacuum state.

  Inside the vacuum chamber 103, guide rolls 104 and 105, tension adjusting rolls 106 and 107, and a cooling can 108 are provided. By the guide rolls 104 and 105, the tension adjusting rolls 106 and 107, and the cooling can 108, the support body 31 travels in the clockwise direction, for example. The belt-like support 31 is attached to the cooling can 108 by connecting both longitudinal ends thereof with, for example, an adhesive tape to form a ring shape.

  The cooling can 108 is configured to be rotatable, and the support 31 travels on the peripheral surface of the cooling can 108 at a constant speed. A cooling mechanism (not shown) is provided inside the cooling can 108, and the cooling mechanism is cooled by an external cooling device (not shown). Thereby, the deformation | transformation etc. by the temperature rise of the support body 31 can be suppressed.

  The tension adjusting rolls 106 and 107 control the tension of the support 31 so that the support 31 runs smoothly without deformation. The tension adjusting rolls 106 and 107 are appropriately controlled by a tension adjusting mechanism (not shown). The guide rolls 104 and 105, the tension adjustment rolls 106 and 107, and the cooling can 108 have, for example, a cylindrical shape having a length larger than the width of the support 31.

  The crucible 109 is for forming the optically anisotropic film 32 on the support 31 that travels on the peripheral surface of the cooling can 108 at a constant speed. The optically anisotropic film 32 is formed in the crucible 109. The material according to the structure is put.

  An electron gun 111 is provided below the crucible 109, and an electron beam 112 emitted from the electron gun 111 is deflected 270 degrees by a deflection magnetic field (not shown), and is irradiated onto the inorganic material 110 in the crucible 109. As a result, the inorganic material 110 in the crucible 109 evaporates and is deposited on the support 31 that runs on the peripheral surface of the cooling can 108 at a constant speed.

  A shutter 113 is provided between the cooling can 108 and the crucible 109 in the vicinity of the cooling can 108. The shutter 113 is provided so as to cover a predetermined region of the support 31 that travels on the peripheral surface of the cooling can 108 at a constant speed. The shutter 113 allows the inorganic material 110 evaporated to the support 31 to have a predetermined value. It is designed to be deposited obliquely in the angle range.

As shown in FIG. 6, the crucible 109 is provided so that the inorganic material 110 evaporated in the crucible 109 is incident on the traveling surface of the cooling can 108 obliquely. The angle θ formed by the normal line of the running surface of the cooling can 108 and the incident direction of the inorganic material evaporated from the crucible 109 is selected in the range of 95 degrees to 175 degrees, for example. Thereby, the inorganic material 110 can be grown obliquely on the film formation surface of the support 31. For example, when Ta ₂ O ₅ or the like is used as the inorganic material 110, a columnar structure inclined with respect to the film formation surface of the support 31 can be formed.

More specifically, for example, the crucible 109 is provided so that the inorganic material 110 is incident on the belt-like support 31 that is traveled by the cooling can 108 obliquely from the longitudinal direction or the lateral direction. Thereby, the inorganic material 110 can be grown on the film-forming surface of the belt-like support 31 in the direction inclined in the short side direction or the long side direction. For example, when Ta ₂ O ₅ or the like is used as the inorganic material 110, a columnar structure inclined in the short side direction or the long side direction of the support 31 can be formed.

  The crucible 114 is for forming the optical isotropic film 33 on the support 31 that travels on the peripheral surface of the cooling can 108 at a constant speed. The optical isotropic film 33 is formed in the crucible 114. The material according to the structure is put.

  An electron gun 116 is provided below the crucible 114, and an electron beam 117 emitted from the electron gun 116 is deflected 270 degrees by a deflection magnetic field (not shown) and irradiated onto the inorganic material 115 in the crucible 114. Then, the evaporated inorganic material 115 is deposited on the support 31 that runs on the peripheral surface of the cooling can 108 at a constant speed.

As shown in FIG. 7, the crucible 114 is provided so that the inorganic material 115 evaporated in the crucible 114 enters perpendicularly to the running surface of the cooling can 108. Thereby, the inorganic material 115 can be grown vertically on the film formation surface of the support 31. For example, when Ta ₂ O ₅ or the like is used as the inorganic material 115, a columnar structure can be formed perpendicular to the film formation surface of the support 31.

(4) Manufacturing method of reflective polarizer Next, the manufacturing method of the reflective polarizer by one Embodiment of this invention is demonstrated.

  First, both ends in the longitudinal direction of the support 31 having a belt shape are connected to the cooling can 108 by connecting them with, for example, an adhesive tape to form a ring shape. Next, after the inside of the vacuum chamber 103 is evacuated to a predetermined degree of vacuum by the evacuation system 102, the support 31 is caused to travel at a constant speed by the cooling can 108.

  Then, the electron gun 111 and the electron gun 116 are operated to irradiate the inorganic material 110 in the crucible 109 and the inorganic material 115 in the crucible 114 with the electron beam 112 and the electron beam 117, respectively. Thereby, the inorganic material 110 and the inorganic material 115 are heated and evaporated.

  The evaporated inorganic materials 110 and 115 are deposited on the support 31 that runs on the peripheral surface of the cooling can 108 at a constant speed. Specifically, the inorganic material 110 evaporated from the crucible 109 is incident on the peripheral surface of the support 31 that is traveled by the cooling can 108 from an oblique direction. Thereby, the optical anisotropic film 32 is formed. On the other hand, the inorganic material 115 evaporated from the crucible 114 enters from a direction perpendicular to the peripheral surface of the support 31 that is run by the cooling can 108. Thereby, the optical isotropic film 33 is formed.

  Since the ring-shaped support 31 periodically passes over the crucible 109 and the crucible 114, the optical anisotropic film 32 and the optical isotropic film 33 are alternately stacked on the support 31. The film thickness, refractive index, and birefringence Δn of the optically anisotropic film 32 and the optically isotropic film 33 are controlled by the film forming conditions. Thus, the target reflective polarizer 24 is produced.

According to one embodiment of the present invention, the following effects can be obtained.
The reflective polarizer 24 is produced by alternately laminating the optically anisotropic film 32 and the optically isotropic film 33 made of an inorganic material on the support 31 by using a thin film deposition method in a vacuum. It is possible to manufacture a reflective polarizer 24 that is less susceptible to ultraviolet deterioration, thermal deformation, and the like and has excellent weather resistance. Furthermore, by using a thin film deposition method in a vacuum, the film thickness can be controlled on the nano-order, and a birefringent film made of an inorganic material having a large area can be obtained. Further, by alternately laminating the optically anisotropic film 32 and the optically isotropic film 33 made of an inorganic material, a high-performance reflective polarizer 24 having a small incident angle dependency can be manufactured. For example, Red, Green, High-performance polarized light separation characteristics can be obtained over the entire visible light range by combining the layers of each blue band.

  In addition, the crucible 109 as the first vaporization source is inclined with respect to the traveling surface of the cylindrical cooling can 108 and the crucible 114 as the second vaporization source is disposed with respect to the traveling surface of the cylindrical cooling can 108. Are disposed opposite to each other, and the inorganic material is evaporated from the crucible 109 and the crucible 114 while the belt-shaped support 31 is running on the cylindrical cooling can 108. An optical anisotropic film 32 in which an inorganic material is grown in an inclined direction, and an optical isotropic film 33 in which an inorganic material is grown in a direction perpendicular to the film formation surface of the band-shaped support 31. Further, it can be alternately laminated on the film forming surface of the belt-like support 31.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

Example 1
First, Ta ₂ O ₅ was put in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate Ta ₂ O ₅ contained in the crucible 109 and the crucible 114. Thereby, the reflective polarizer 24 in which the optically anisotropic film 32 and the optically isotropic film 33 made of Ta ₂ O ₅ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of optically anisotropic films 32 and optically isotropic films 33 alternately laminated on the transparent film 31 is 300, and the birefringence Δn of the optically anisotropic film 32 is 0. 03. The birefringence was measured using a retardation measuring device (trade name: RETS-100, manufactured by Otsuka Electronics Co., Ltd.).

Example 2
First, Ta ₂ O ₅ was put in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate Ta ₂ O ₅ contained in the crucible 109 and the crucible 114. Thereby, the reflective polarizer 24 in which the optically anisotropic film 32 and the optically isotropic film 33 made of Ta ₂ O ₅ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of optical anisotropic films 32 and optical isotropic films 33 laminated alternately on the transparent film 31 is 270, and the birefringence Δn of the optical anisotropic film 32 is 0. 05. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Example 3
First, CeO ₂ was put in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate CeO ₂ contained in the crucible 109 and the crucible 114. Thereby, the reflective polarizer 24 in which the optically anisotropic film 32 and the optically isotropic film 33 made of CeO ₂ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of optically anisotropic films 32 and optically isotropic films 33 alternately laminated on the film 31 is 240, and the birefringence Δn of the optically anisotropic film 32 is 0.07. It was. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Example 4
First, CeO ₂ was put in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate CeO ₂ contained in the crucible 109 and the crucible 114. Thereby, the reflective polarizer 24 in which the optically anisotropic film 32 and the optically isotropic film 33 made of CeO ₂ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of layers of the optically anisotropic film 32 and the optically isotropic film 33 alternately stacked on the film 31 is 210, and the birefringence Δn of the optically anisotropic film 32 is 0.09. It was. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Example 5
First, Ta ₂ O ₅ and CeO ₂ were placed in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate Ta ₂ O ₅ and CeO ₂ contained in the crucible 109 and the crucible 114. As a result, a reflective polarizer 24 in which optically anisotropic films 32 and optically isotropic films 33 made of Ta ₂ O ₅ and CeO ₂ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of optically anisotropic films 32 and optically isotropic films 33 alternately stacked on the film 31 is 180, and the birefringence Δn of the optically anisotropic film 32 is 0.11. It was. In addition, the apparatus similar to Example 1 was used for the measurement of a film thickness and a refractive index. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Example 6
First, Ta ₂ O ₅ and CeO ₂ were placed in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate Ta ₂ O ₅ and CeO ₂ contained in the crucible 109 and the crucible 114. As a result, a reflective polarizer 24 in which optically anisotropic films 32 and optically isotropic films 33 made of Ta ₂ O ₅ and CeO ₂ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of optically anisotropic films 32 and optically isotropic films 33 alternately laminated on the film 31 is 150, and the birefringence Δn of the optically anisotropic film 32 is 0.13. It was. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Example 7
First, Ta ₂ O ₅ was put in the crucible 109 and the crucible 114 provided in the reflective polarizer manufacturing apparatus 101. Next, both ends of the transparent film (support) 31 having a belt-like shape were joined with an adhesive tape and attached to the cooling can 108 in the vacuum chamber 103. Next, after the vacuum chamber 103 was evacuated, the transparent film 31 was run. Thereafter, the electron gun 111 and the electron gun 116 were operated to evaporate Ta ₂ O ₅ contained in the crucible 109 and the crucible 114. Thereby, the reflective polarizer 24 in which the optically anisotropic film 32 and the optically isotropic film 33 made of Ta ₂ O ₅ were alternately laminated on the transparent film 31 was obtained.

  Here, the total number of layers of the optically anisotropic film 32 and the optically isotropic film 33 alternately stacked on the film 31 is 390, and the birefringence Δn of the optically anisotropic film 32 is 0.02. It was. In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Comparative Example Polyethylene naphthalate (PEN) was formed into a film by melt extrusion, and then stretched, and an optically anisotropic film obtained by stretching and a film of naphthalenedicarboxylic acid and isotalic acid copolyester (coPEN) by melt extrusion Then, an optically isotropic form obtained by stretching was alternately laminated, and this laminate was adhered to a transparent film (support) to obtain a reflective polarizer.

  Here, the total number of optically anisotropic films and optically isotropic films laminated alternately on the transparent film 31 is 300, and the birefringence Δn of the optically anisotropic film is 0.03. . In addition, the apparatus similar to Example 1 was used for the measurement of a refractive index.

Next, the weather resistance of Examples 1 to 7 and Comparative Examples obtained as described above was evaluated. This weather resistance was evaluated as follows. The weather resistance test was performed using a weather resistance test apparatus Ci3000 manufactured by ATLAS. This apparatus uses a xenon lamp as a light source, and the test conditions were a radiation exposure amount of 360 kJ / mm ² , a temperature of 45 ° C., and a humidity of 30% (DRY) for 10 days. In the evaluation, the discoloration of the sample before and after the test was confirmed, and “◯” indicates no discoloration and “×” indicates discoloration.

Table 1 shows the evaluation results of the weather resistance of Examples and Comparative Examples. In Table 1, the number of layers is the value of the total number of optical anisotropic films 32 and optical isotropic films 33 alternately stacked on the transparent film 31.

  From Table 1, it can be seen that the reflective polarizers 24 of Examples 1 to 7 have less ultraviolet deterioration, thermal deformation, and the like and improved weather resistance as compared with the comparative example. That is, in the reflective polarizer 24 of Examples 1-7, compared with the conventional reflective polarizer which has the structure which laminated | stacked the polymeric optically anisotropic film and the optically isotropic film on the transparent film, weather resistance It can be seen that can be improved.

  It can also be seen that if the birefringence is less than 0.03, the number of layers of the laminated film exceeds 300 layers. Accordingly, it can be seen that it is preferable to set the birefringence to 0.03 or more in order to suppress the decrease in productivity and the increase in cost of the reflective polarizer 24.

  In addition, the present inventor observed the cross sections of the reflective polarizers 24 of Examples 1 and 2 and Examples 5 and 6 manufactured as described above. From the observation results, the columnar structure was clearly observed in Example 1 and Example 2, whereas in Example 5 and Example 6, the film-forming material was observed in a granular form, but the columnar structure was observed. Was not observed.

  From this observation result, it can be seen that optical anisotropy can be obtained as shown in Table 1 even in the case of Example 5 and Example 6 in which the columnar structure is not formed. That is, it can be seen that the configuration of the optical anisotropic film 32 is not limited to the columnar structure.

  The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

In the above-described embodiment, the thickness of the optical anisotropic film 32 and the optical isotropic film 33 is increased while the optical anisotropic film 32 and the optical isotropic film 33 are laminated on the support 31. You may make it change the length. In this case, the traveling speed of the support 31 may be changed while the optically anisotropic film 32 and the optically isotropic film 33 are being laminated on the support 31. For example, a _first laminate formed by laminating an optically anisotropic film 32 and an optically isotropic film 33 having a film thickness d ₁ , an optically anisotropic film 32 and an optically isotropic film having a film thickness d ₂ A second laminated body formed by laminating 33,..., An _nth laminated body formed by laminating an optically anisotropic film 32 having a film thickness d _n and an optically isotropic film 33 on the support 31. sequentially when stacked, by as each of laminating a laminate of the first to n respectively, the film thickness by appropriately changing the traveling speed becomes _{d 1, d 2, ···,} d n to That's fine.

It is sectional drawing which shows one structural example of the liquid crystal display device by one Embodiment of this invention. It is sectional drawing which shows one structural example of the reflective polarizer by one Embodiment of this invention. It is sectional drawing in the xz plane of the reflective polarizer which has a columnar structure. It is sectional drawing in yz plane of the reflective polarizer which has a columnar structure. It is a schematic diagram which shows one structural example of the manufacturing apparatus of the reflective polarizer by one Embodiment of this invention. It is a schematic sectional drawing which shows the positional relationship of the crucible which is a 1st vaporization source, and a cooling can. It is a schematic sectional drawing which shows the positional relationship of the crucible which is a 2nd vaporization source, and a cooling can.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal panel 3 1st board | substrate 4 2nd board | substrate 5 Spacer 6 Liquid crystal layer 7 Backlight 24 Reflective polarizer 31 Support body 32 Optical anisotropic film 33 Optical isotropic film 101 Manufacture of reflective polarizer Device 108 Cooling can 110, 115 Inorganic material 109, 114 Crucible

Claims (11)

Inorganic thin films having optical anisotropy and inorganic thin films having optical isotropy are alternately laminated on a transparent support,
The inorganic thin film having optical anisotropy and the inorganic thin film having optical isotropy have the same refractive index in one polarization direction of incident light, and in the other polarization direction orthogonal to the one polarization direction. A reflective polarizer having different refractive indexes.   The reflective polarizer according to claim 1, wherein the inorganic thin film having optical anisotropy has a birefringence (Δn) of 0.03 or more. The inorganic thin film having optical anisotropy has a columnar structure inclined with respect to the main surface of the transparent support,
The optically isotropic inorganic thin film has a columnar structure perpendicular to the main surface of the transparent support,
The columnar structure is periodically repeated in the in-plane direction,
The reflective polarizer according to claim 1, wherein the interval between the columnar structures is narrower than the wavelength of visible light.   The columnar structure of the inorganic thin film having optical anisotropy is characterized in that it is tilted by 5 degrees or more and 85 degrees or less toward the other polarization direction with respect to the normal line of the main surface of the transparent support. The reflective polarizer according to claim 3.   4. The reflective polarizer according to claim 3, wherein the columnar structure of the inorganic thin film having optical anisotropy is 100 nm or less.   A liquid crystal display device comprising the reflective polarizer according to any one of claims 1 to 5 between a liquid crystal panel and a light source. Forming an optically anisotropic film by causing an inorganic material to be incident from an oblique direction with respect to the main surface of the transparent support by the first vaporization source;
Forming an optically isotropic film by causing an inorganic material to enter from a direction perpendicular to the main surface of the transparent support by a second vaporization source;
A method of manufacturing a reflective polarizer, characterized in that is alternately repeated.   The step of forming the optically anisotropic film is characterized in that an angle formed by a normal direction of a main surface of the transparent support and an incident direction of the inorganic material is 95 degrees or more and 175 degrees or less. 8. A method for producing a reflective polarizer according to item 7.   The step of forming the optically anisotropic film and the optically isotropic film by running the transparent support so as to periodically pass over the first vaporization source and the second vaporization source. The method of manufacturing a reflective polarizer according to claim 7, wherein the film forming step is alternately repeated. Traveling means for traveling the transparent support;
A first vaporization source for injecting an inorganic material from an oblique direction with respect to the transparent support traveled by the travel means;
A second vaporization source for allowing the inorganic material to enter from a direction perpendicular to the transparent support traveled by the travel means,
The apparatus for manufacturing a reflective polarizer, wherein the travel means travels the transparent support so that the transparent support periodically passes over the first vaporization source and the second vaporization source. .   The first vaporization source is provided such that an angle formed by a normal direction of a main surface of the transparent support and an incident direction of the inorganic material is 95 degrees or more and 175 degrees or less. The apparatus for manufacturing a reflective polarizer according to claim 10.

Images