JP2009300654A - Wire grid polarizer and display device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire grid polarizer that has achieved excellent durability and high light use efficiency with a simple configuration, and can achieve sufficient color reproducibility and black display when incorporated into a display device such as a liquid crystal display device. <P>SOLUTION: The wire grid polarizer is a composite type wire grid polarizer formed by superposing an absorption type wire grid polarizer 1 in which absorption type polarizing components are arranged on a substrate in a grid-like formation and a reflection type wire grid polarizer 2 in which reflection type polarizing components are arranged on a substrate in a grid-like formation. At least the absorption type wire grid polarizer 1 is composed of a substrate 1b having convex portions in a grid-like formation, and a layer 1a including absorption type polarizing components formed on the convex portions of the substrate 1b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wire grid polarizer and a display device using the same.

  With the recent development of photolithography technology, it has become possible to form a fine structure pattern having a pitch at the wavelength level of light. Such a member or product having a pattern with a very small pitch is useful not only in the semiconductor field but also in the optical field (Non-Patent Document 1).

  For example, a wire grid in which conductor wires made of metal or the like are arranged in a lattice pattern at a specific pitch has a pitch that is considerably smaller than incident light (for example, visible light wavelength 400 nm to 800 nm). For example, if it is less than half, most of the electric field vector component light that oscillates in parallel to the conductor line is reflected, and almost no electric field vector component light perpendicular to the electric conductor line is transmitted. Can be used as a polarizer to produce a single polarization. Since this wire grid polarizer can reflect and reuse light that does not transmit, it is also desirable from the viewpoint of effective use of light.

  An example of such a wire grid polarizer is disclosed in Patent Document 1. The wire grid polarizer includes metal wires spaced at a grid period smaller than the wavelength of incident light. This wire grid polarizer has a polarization property that the electric field component reflects the polarization component (TM wave) parallel to the metal wire and transmits the polarization component (TE wave) perpendicular to the metal wire, and is often used as a beam splitter. Has been.

  However, since the polarized component is separated by reflection, there is a problem that it is difficult to use the reflected polarized component in applications where it is not preferable. When the wire grid polarizer is disposed in a display device such as a liquid crystal display device, In the configuration disclosed in Patent Document 1, the metal wire reflects not only the light from the backlight side but also the light from the outside light side, so that sufficient color reproducibility and black display cannot be performed. was there.

  As other polarizers, absorptive dichroic polarizers are widely used. An absorptive dichroic polarizer can be obtained by stretching a polymer film coated with a compound having absorption anisotropy of light (iodine, dichroic dye). When this absorptive polarizer is used for a display device, the transmittance does not exceed 50% in principle, and there is a problem that the light use efficiency is low. Furthermore, there was also a problem inferior in durability in a high temperature and high humidity environment (Non-patent Document 2).

To solve the above problems, a polarizer combining a wire grid polarizer and an absorptive dichroic polarizer (Patent Document 2), or a polarizer combining a reflective wire grid polarizer and a light absorbing material (Patent Document 3). Patent Document 4) has been proposed.
Bulletin of Japan Women's University Faculty of Science No. 14 (2006) Optical Materials for FPD Monthly Display October issue separate volume (2007) Techno Times JP 2003-502708 A JP 2007-57873 A JP-A-2005-37900 JP 2008-46637 A

  However, in the configuration described in Patent Document 2, since an absorptive dichroic polarizer is used as a part of the polarizer, durability in a high-temperature and high-humidity environment tends to be inferior, and a change in polarization degree with time is likely to occur. There was a problem.

  Further, as described in Patent Documents 3 and 4, in the configuration in which a light absorbing material is laminated on the wire grid of the reflective wire grid polarizer, a multilayer film such as a dielectric, a low reflection metal, and an oxide is vacuum-deposited. As a result, it is necessary to process the multilayer film into a wire shape with a pattern of several hundreds of nanometers, so that it takes time to form and process the multilayer film.

  In addition, since the types of gases that are optimal for dry etching in the microfabrication of metals, dielectrics, and oxides that make up multilayer films into wire shapes differ between the metal phase, oxide layer, and dielectric layer, etching is performed. In wet etching, there is a problem that it is difficult to select an optimal etching solution.

  In addition, as described in Patent Document 3, in a configuration in which a striped grating layer is formed on the front and back surfaces of the base material with a reflective material and an absorptive material, respectively, it is installed at a position optically parallel on the front and back surfaces of the flat substrate However, as a procedure, a striped grating layer is provided on one side of the flat substrate, and a striped grating layer is provided on the other side plane while maintaining the optical parallel position. However, it is difficult to provide a grating layer on both surfaces of the base material while maintaining parallelism. Here, the optical parallel position means a position where the polarization axes transmitting through the polarizer are parallel to each other.

  Further, by the inventors' investigation, the configuration described in Patent Document 3 can suppress the reflectance of the TM wave at the incidence from the absorbent material side, but the reflectance of the TE wave is also high, and natural light observed as a result is observed. It is known that the reflectivity cannot be completely suppressed.

  The present invention has been made in view of the above points, and has a simple structure, excellent durability, high light utilization efficiency, and sufficient color reproducibility when disposed in a display device such as a liquid crystal display device. Another object of the present invention is to provide a wire grid polarizer that can realize black display.

  The wire grid polarizer of the present invention includes an absorption wire grid polarizer in which absorption polarization components are arranged in a grid on a substrate, and a reflection wire grid polarization in which reflection polarization components are arranged in a grid on the substrate. And a composite wire grid polarizer in which at least the absorption wire grid polarizer is formed on a base material having convex portions in a lattice shape and on the convex portions of the base material. And a layer composed of an absorbing polarization component.

  In the wire grid polarizer of the present invention, it is preferable that the layer is formed only on one side of the cross-sectional slope portion of the lattice-like convex portion of the base material.

  In the wire grid polarizer of the present invention, the layer is a layer composed of an oxide selected from the group consisting of aluminum oxide, iron oxide, nickel oxide, copper oxide, vanadium oxide, and chromium oxide, and the group It is preferable that the height in the perpendicular direction from the lattice-like convex portion of the material is 8 nm or more and 250 nm or less.

  In the wire grid polarizer of the present invention, the layer includes W, V, Cr, Co, Mo, Ge, Ir, Ni, Os, Ti, Fe, Nb, Hf, Mn, Ta, and at least one of them. It is preferable that the layer is made of at least one metal selected from the group consisting of an alloy as a main component, and the layer is formed with a thickness of 5 nm to 30 nm.

  In the wire grid polarizer of the present invention, the reflective wire grid polarizer is composed of a base material having convex portions in a lattice shape and a reflective polarization component formed on the convex portions of the base material. And a layer.

  The display device of the present invention includes a display device, illumination means for irradiating the display device with light, and the wire grid polarizer, and the reflective wire grid polarizer is disposed on the illumination means side. It is characterized by that.

  The wire grid polarizer of the present invention includes an absorption wire grid polarizer in which absorption polarization components are arranged in a grid on a substrate, and a reflection wire grid polarization in which reflection polarization components are arranged in a grid on the substrate. And a composite wire grid polarizer in which at least the absorption wire grid polarizer is formed on a base material having convex portions in a lattice shape and on the convex portions of the base material. A layer composed of an absorptive polarization component, and with a simple structure, it has excellent durability, high light utilization efficiency, and sufficient color reproducibility when disposed in a display device such as an LCD. Black display can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional perspective view showing an example of a wire grid polarizer according to an embodiment of the present invention. The polarizer 3 is a reflective wire grid polarizer 2 disposed with an absorption wire grid polarizer 1 and an absorption wire grid polarizer 1 that absorb incident light 4 sandwiched between a base material 1b and a base material 2b. The reflective wire grid polarizer 2 reflects and polarizes the incident light 5 from the opposite side by 180 degrees across the incident light 4 and the polarizer 3.

  Furthermore, in the case of the aspect which the base materials of the absorption type wire grid polarizer 1 and the reflection type wire grid polarizer 2 contact | abut as shown in FIG. 1, the base material may be integrated previously.

  In the wire grid polarizer of the present invention, when the wire grid polarizer according to the present invention is disposed in a display device such as a liquid crystal display device, in order to realize sufficient color reproducibility and black display, For the light 4, the TM wave transmittance is 0.1% or less, the reflectance is 30% or less, the TE wave transmittance is 70% or more, and the reflectance is preferably 20% or less, For incident light 5, the transmittance of TM wave is 0.1% or less, the reflectance is 60% or more, the transmittance of TE wave is 70% or more, and the reflectance is preferably 20% or less. . With such optical characteristics, external light is not reflected, and only the backlight side is polarized by reflection, so that sufficient color reproducibility and black display can be achieved while maintaining high light use efficiency of the backlight. The transmittance and reflectance of TM waves and TE waves are measured using a spectrophotometer.

  FIG. 2 is an enlarged schematic perspective view of the absorption wire grid polarizer 1 of FIG. The absorptive wire grid polarizer shown in FIG. 2 is an absorptive polarization component erected on a substrate 1b having a lattice-like convex portion 1c on the surface and a region on the substrate 1b including the lattice-like convex portion 1c. It is mainly comprised from the absorption type | mold polarization | polarized-light component wire 1a comprised by these.

  The absorptive polarization component wire 1a needs to cover at least a part of the lattice-shaped convex portion 1c in a cross-sectional view. In particular, it is possible to obtain predetermined optical performance by covering only the slope portion in the cross-sectional view of the grid-like convex portion 1c, and high transmittance is obtained by covering only one side of the slope portion in the cross-sectional view as shown in FIG. The transmittance and the wavelength dispersion of the reflectance can be suppressed with a low reflectance, which is more preferable. The reason why it is possible to suppress the wavelength dispersion of the optical characteristics with high transmittance by covering only one side of the slope in the sectional view of the convex part is unknown, but from the effective medium theory, the absorption-type polarization component wire 1a and the lattice shape with respect to the incident direction of light It is estimated that the change in the cross section of the convex portion 1c suppresses a rapid change in optical characteristics with respect to the light incident direction.

  In the absorptive wire grid polarizer of the present invention, in the TM wave, the transmittance is preferably 50% or less and the reflectance is 40% or less, the transmittance is 40% or less, and the reflectance is More preferably, it is 20% or less. In the TE wave, the transmittance is preferably 80% or more and the reflectance is preferably 10% or less, more preferably 85% or more and the reflectance is 8% or less.

  The material used for the substrate 1b may be a material that is substantially transparent in the visible light region, but is preferably a resin excellent in workability. For example, polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cycloolefin resin (COP), cross-linked polyethylene resin, polyvinyl chloride resin, polyarylate resin, polyphenylene ether resin, modified polyphenylene ether resin, polyetherimide resin, polyether Amorphous thermoplastic resins such as sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate (PET) resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polybutylene terephthalate resin, aromatic polyester resin, polyacetal Examples include crystalline thermoplastic resins such as resins and polyamide resins, and ultraviolet (UV) curable resins and thermosetting resins such as acrylic, epoxy, and urethane types. That. Moreover, you may use the composite base material which combined the ultraviolet curable resin and the thermosetting resin, inorganic substrates, such as glass, the said thermoplastic resin, and a triacetate resin as the base material 1b.

  The pitch of the grid-like convex portions 1c on the substrate 1b is 150 nm or less, preferably 80 nm to 120 nm in consideration of polarization characteristics over a wide band in the visible light region. The smaller the pitch, the better the polarization characteristics. However, for visible light, sufficient polarization characteristics can be obtained at a pitch of 80 nm to 120 nm. When the polarization characteristics of short wavelength light in the vicinity of 400 nm are not important, the pitch may be increased to about 150 nm.

  In the present invention, the pitch p of the grid-like convex portions 1c on the substrate 1b and the pitch of the absorption-type polarization component wire 1a are substantially equal and can be the same pitch.

  There is no restriction | limiting in the cross-sectional shape of the grid-like convex part 1c on the base material 1b. Examples of the cross-sectional shape include a trapezoidal shape, a rectangular shape, a square shape, a prism shape, and a sine wave shape such as a semicircular shape. Here, the sinusoidal shape means having a curved portion formed by repetition of a concave portion and a convex portion. In addition, the curved part should just be a curved curve, for example, the shape which has a constriction in a convex part is also included in a sine wave form. Further, from the viewpoint of facilitating covering of the lattice-shaped convex portion 1c on the substrate 1b and at least a part of the side surface thereof with the absorbing polarization component, the end portion, the top portion, or the valley portion of the shape is curved with a gentle curvature. It is preferable. Further, from the viewpoint of increasing the adhesion strength between the substrate 1b, the lattice-like convex portion 1c, and the absorption-type polarization component wire 1a, it is more preferable that these cross-sectional shapes are sinusoidal. Further, similarly, it is also preferable to provide a thin film of a transparent dielectric layer (not shown) from the viewpoint of increasing the adhesion strength between the substrate 1b, the lattice-shaped convex portion 1c, and the absorption-type polarization component wire 1a.

  As a method of providing the grid-like convex part 1c on the base material 1b, a method of transferring and molding the grid-like convex part on the surface of the equipment using a mold having a grid-like convex part having a pitch of 150 nm or less on the surface is mentioned. It is done. Here, the mold having a grid-like convex part with a pitch of 150 nm or less on the surface is made conductive in order by applying a resist pattern having a grid-like convex part with a pitch of 150 nm or less, obtained by electron beam lithography or interference exposure. It can be created by performing treatment, plating treatment, and substrate removal treatment.

  As the absorptive polarization component constituting the absorptive polarization component wire 1a, a material that exhibits a function of reducing the vertical reflectance of incident light is used. Specifically, aluminum oxide, iron oxide, nickel oxide, copper oxide, vanadium oxide, chromium oxide, and the like are preferable, and in these oxides, the amount of oxygen with respect to the metal is a non-stoichiometric oxide that is less than a completely oxidized state. Absorption efficiency is increased, and the extinction coefficient k is preferably 0.2 or more and less than 4.0. In addition, it is especially preferable that the extinction coefficient k is in the range of 1.5 or more and 3.5 or less because desired optical characteristics can be obtained with a film thickness of 20 nm or less. These oxides may be used alone or in a mixed state. These non-stoichiometric oxides are formed in a region including the lattice-like convex portion 1c on the substrate 1b, and the height in the perpendicular direction from the substrate 1b is in the range of 8 nm or more and 250 nm or less, and desired optical characteristics. Preferably, it is more preferable that it is in the range of 10 nm or more and 200 nm or less because the optical characteristics are in a more preferable range. Here, the height in the perpendicular direction refers to the maximum thickness in the cross-sectional view of the absorption-type polarization component wire 1a in the direction substantially parallel to the axial direction of the cross-section convex portion of the lattice-like convex portion from the surface of the substrate 1b. In FIG.

  Furthermore, from the viewpoint of protecting the absorption-type polarization component wire 1a, it is also preferable to provide a thin film of a transparent dielectric layer (not shown) laminated on the absorption-type polarization component wire 1a. The method for forming the dielectric layer on the absorption-type polarization component wire 1a is appropriately selected depending on the material constituting the dielectric layer. For example, a physical vapor deposition method such as a sputtering method or a vacuum vapor deposition method can be suitably used.

  FIG. 3 is a schematic cross-sectional perspective view showing an example of another configuration in the absorption wire grid polarizer 1 of the present invention in an enlarged manner.

  As the absorption polarization component constituting the absorption polarization component wire 1d in FIG. 3, W, V, Cr, Co, Mo, Ge, Ir, Ni, Os, Ti, Fe, Nb, Hf, Mn, Ta And at least one low reflection metal selected from the group consisting of, or a low reflection metal such as an alloy mainly composed of at least one material selected from the group. These low reflection metals constitute the absorbing polarization component wire 1d. The low reflection metal wire 1d is preferably formed of a thin film having a thickness of 5 nm or more and 30 nm or less on one inclined surface in a cross-sectional view of the substrate 1c. The thickness of the thin film is more preferably 8 nm or more and 20 nm or less.

  Since the low reflection metal wire 1d is a thin film, the reflectance and transmittance of the TM wave can be suppressed low and the absorption rate can be increased despite being a wire grid polarizer. The details of the increase in the TM wave absorptivity with a thin low-reflection metal wire are not clear, but it is presumed that the absorption inside the low-reflection metal increases because it is the same as the penetration depth of the low-reflection metal.

  When the above-mentioned thin low-reflection metal is used as the absorptive polarization component, the reflectance on the absorptive wire grid polarizer side is low when integrated with a later-described reflective wire grid polarizer, and the reflective wire grid polarizer Since the reflectance of incident light from the side increases, it is particularly preferable when applied to a display device such as a liquid crystal because the light utilization efficiency on the backlight side is improved.

  As a method for forming the absorbing polarization component on the substrates 1b and 1c to form the absorbing polarization component wires 1a and 1d, sufficient adhesion can be obtained between the absorbing polarization component and the substrate. If it is a method, it will not specifically limit. For example, a physical vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or an ion plating method can be suitably used. A method in which selective lamination can be performed while being biased toward one slope portion of the lattice-shaped convex portion is preferable, and an oblique vapor deposition method and the like can be given.

  Also in FIG. 3, as described above, it is also preferable to provide a protective layer by laminating a thin film of a dielectric layer (not shown).

Next, the reflective polarizer in the polarizer of the present invention will be described with reference to the drawings.
FIG. 4 is a schematic cross-sectional perspective view showing the reflective wire grid polarizer 2 of FIG. 1 in an enlarged manner. The reflective wire grid polarizer shown in FIG. 4 has a base material 2b having a grid-like convex part 2c on the surface, a grid-like convex part 2c, and a region on the base material 2b including the grid-like convex part 2c. It is mainly composed of a standing metal wire 2a composed of a reflective polarization component.

  In the reflective wire grid polarizer of the present invention, in TM waves, the transmittance is preferably 1% or less, and the reflectance is preferably 40% or more, the transmittance is 0.1% or less, and The reflectance is more preferably 50% or more. In the TE wave, the transmittance is preferably 70% or more and the reflectance is 20% or less, more preferably 75% or more and the reflectance is 10% or less.

  The material used for the substrate 2b may be a material that is substantially transparent in the visible light region, but is preferably a resin excellent in workability. For example, polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cycloolefin resin (COP), cross-linked polyethylene resin, polyvinyl chloride resin, polyarylate resin, polyphenylene ether resin, modified polyphenylene ether resin, polyetherimide resin, polyether Amorphous thermoplastic resins such as sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate (PET) resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polybutylene terephthalate resin, aromatic polyester resin, polyacetal Examples include crystalline thermoplastic resins such as resins and polyamide resins, and ultraviolet (UV) curable resins and thermosetting resins such as acrylic, epoxy, and urethane types. That. Moreover, you may use the composite base material which combined the ultraviolet curable resin and the thermosetting resin, inorganic substrates, such as glass, the said thermoplastic resin, and a triacetate resin as the base material 2b.

  The pitch of the grid-like convex portions 2c of the substrate 2b is 150 nm or less, preferably 80 nm to 120 nm in consideration of polarization characteristics over a wide band in the visible light region. The smaller the pitch, the better the polarization characteristics. However, for visible light, sufficient polarization characteristics can be obtained at a pitch of 80 nm to 120 nm. When the polarization characteristics of short wavelength light in the vicinity of 400 nm are not important, the pitch may be increased to about 150 nm.

  In the present invention, the pitch of the grid-like convex portions 2c on the substrate 2b and the pitch of the metal wires 2a are substantially equal and can be the same pitch. Moreover, it is not necessary to make the pitch the same as that of the absorption wire grid polarizer 1 described above, and the prior pitches of the absorption type and the reflection type can be appropriately made independent.

  There is no restriction | limiting in the cross-sectional shape of the grid-like convex part 2c on the base material 2b. Examples of the cross-sectional shape include a trapezoidal shape, a rectangular shape, a square shape, a prism shape, and a sine wave shape such as a semicircular shape. Here, the sinusoidal shape means having a curved portion formed by repetition of a concave portion and a convex portion. In addition, the curved part should just be a curved curve, for example, the shape which has a constriction in a convex part is also included in a sine wave form. In addition, from the viewpoint of facilitating the metal material to cover at least part of the lattice-like convex portions 2c on the base material 2b and the side surfaces thereof, the end portion, the top portion, or the valley portion of the shape is curved with a gentle curvature. preferable. Moreover, it is more preferable that these cross-sectional shapes are sinusoidal from the viewpoint of increasing the adhesion strength between the base material 2b, the lattice-like convex portions 2c and the metal wires 2a. Further, similarly, it is also preferable to provide a thin film of a transparent dielectric layer (not shown) from the viewpoint of increasing the adhesion strength between the base material 2b, the lattice-like convex portion 2c, and the metal wire 2a.

  As a method of providing the grid-like convex part 2c on the base material 2b, a method of transferring and molding the grid-like convex part on the surface of the equipment using a mold having a grid-like convex part having a pitch of 150 nm or less on the surface is mentioned. It is done. Here, the mold having a grid-like convex part with a pitch of 150 nm or less on the surface is made conductive in order by applying a resist pattern having a grid-like convex part with a pitch of 150 nm or less, obtained by electron beam lithography or interference exposure. It can be created by performing treatment, plating treatment, and substrate removal treatment.

  The metal constituting the metal wire 2a is preferably a metal having high light reflectance in the visible light region and good adhesion to the substrates 2b and 2c. For example, it is preferably made of aluminum (Al), silver (Ag), tin (Sn), or an alloy thereof. From the viewpoint of cost, it is preferably made of Al or an Al alloy.

  The absorptive wire grid polarizer and the reflective wire grid polarizer described above are bonded at an optical parallel position to obtain the polarizer of the present invention. Examples of the method for bonding at an optically parallel position include the following methods.

  In FIG. 5, the linearly polarized light transmitted through the existing polarizer 12 is transmitted through the absorption polarizer 11. The absorptive polarizer 11 is rotated around the optical axis of the transmitted light 10 so that the amount of the transmitted light 10 is minimized. The side 11a of the absorptive polarizer 11 is cut in accordance with a base to which a polarizer 12 (not shown) is fixed. By such an operation, the side 11 a becomes parallel to the polarization axis of the polarizer 12. Similarly, for the reflective polarizer, a side parallel to the polarization axis of the polarizer 12 is obtained. Next, the wire grid polarizer of the present invention in which the absorption polarizer and the reflection polarizer are integrated at an optical parallel position is obtained by laminating the sides while mechanically matching them.

  The direction of stacking may be such that each of the reflection type and absorption type wire grids is 180 degrees opposite to the incident light. As shown in FIG. 6, the wire grid of the absorption type wire grid polarizer 1 is the reflection type wire. It may be laminated on the back surface of the grid polarizer 2 via an adhesive layer 7, or may be laminated at a position where an absorption type and a reflection type wire grid (not shown) face each other. When laminating at the position where the wire grid faces, the optical characteristics change when the adhesive layer is filled between the wires of the wire grid, and therefore, it is preferable that the adhesive layer is in contact with only the top of the wire.

  As described above, since it is possible to obtain a wire grid polarizer in which the wire grid polarizers are arranged in an optically parallel position, it can be manufactured at low cost with a simple apparatus. Further, since each polarizer is independent until it is bonded, an optimum and easy manufacturing method can be selected for each polarizer, and there is a great advantage in actual industrial production in view of production efficiency and cost.

  The above is an example of a manufacturing method in which a reflection type and an absorption type wire grid polarizer are individually formed and bonded, but the reflection type and absorption type are formed on the front and back of the substrate in which the wire grid polarizer of the present invention is integrated. It can also be obtained by laminating a wire grid polarizer.

  FIG. 7 is a schematic cross-sectional perspective view showing an example of a base material 8 having a grid-like convex part on the front and back for laminating the reflection type and the absorption type on the integrated front and back. The front and back grid-like convex portions are formed at positions parallel to each other. Examples of the method of forming the grid-like convex portions parallel to each other on the front and back include a method of transferring the grid-like convex portions to the surface of the substrate using a mold having a grid-like convex portion having a pitch of 150 nm or less on the surface, A method of transferring while mechanically holding the parallel positions of the mold-like convex portions of the mold to be transferred to the front and back of the substrate, and after transferring to one side, rotate 180 degrees along the rotation axis parallel to the lattice-like convex portions of the mold And transferring to the other side.

  In the wire grid polarizer of the present invention, the direction of the metal wire that realizes the polarization characteristics and the absorption type polarization component wire are determined by the lattice-shaped convex portions on the surface of the base material. If the base material which maintained the parallelism of the grid-like convex portions is used, the polarizer of the present invention having reflection and absorption type wire grid polarizers on the front and back at an optical parallel position can be easily obtained.

  Furthermore, the characteristics of the obtained polarizer have the same performance as the polarizer obtained by individually creating and bonding the reflection type and absorption type wire grid polarizers as described above. Since it may be the same as that of a single wire grid polarizer and is formed on the front and back of the substrate, an optimal and easy manufacturing method can be selected on the front and back, and there is a great advantage in practical industrial production in terms of production efficiency and cost.

  In the wire grid polarizer of the present invention, since it is an inorganic substance that has a polarization function, it has excellent durability against heat and light.

Next, the case where it is used for the liquid crystal display device according to the present invention will be described with reference to the drawings.
FIG. 8 is a schematic cross-sectional view showing a liquid crystal display device using a polarizer according to an embodiment of the present invention.

  The liquid crystal display device shown in FIG. 8 mainly includes an illumination device 20 such as a backlight that emits light, a polarizer 21 of the present invention disposed on the illumination device, and a liquid crystal cell 23 sandwiched between the polarizers 22. Is done. The polarizers 21 and 22 according to the present invention are arranged with the reflective polarizers 21a and 22a facing the backlight side. The liquid crystal cell 23 is a transmissive liquid crystal cell and is configured by sandwiching a liquid crystal material or the like between glass and a transparent resin substrate. In the liquid crystal display device of FIG. 8, the description of various optical elements such as a polarizer protective film, a retardation film, a diffusion plate, an alignment film, a transparent electrode, and a color filter that are usually used is omitted.

  In the liquid crystal display device having such a configuration, light emitted from the illuminating device 20 is incident from the reflective wire grid polarizer 21a of the wire grid polarizer 21, passes through the liquid crystal cell 23, and again is the wire grid polarizer 22. The reflection type wire grid polarizer 22a enters and exits to the outside (30 in the figure). In this case, since the wire grid polarizers 21 and 22 exhibit an excellent degree of polarization in the visible light region, it is possible to obtain a display with high contrast. In addition, incident light from the illumination device 20 that does not transmit is reflected toward the illumination device side and reused to obtain high luminance.

  On the other hand, external light enters from the absorption wire grid polarizer 22b of the wire grid polarizer 22, passes through the liquid crystal cell 23, enters again from the absorption wire grid polarizer 21b of the wire grid polarizer 21, and the illumination device 20 (31 in the figure). In this case, external light that does not pass through is efficiently absorbed by the wire grid polarizer of the present invention. In summary, sufficient color reproducibility and black display can be realized in a liquid crystal display device.

  Next, examples performed to clarify the effects of the present invention will be described. In addition, the dimension, material, etc. in the following embodiment are illustrative and can be implemented with appropriate changes. Other modifications can be made without departing from the scope of the present invention.

[Example 1]
(Creation of a base material having a grid-like convex portion)
-Creation of fine concavo-convex lattice shape A fine concavo-convex lattice was formed on a substrate coated with a photoresist on glass by using an electron beam drawing method. When the surface and cross section of this resist pattern were observed with a field emission scanning electron microscope (STEM), the pitch and height of the fine concavo-convex grating were 145 nm / 130 nm (pitch / height), and the cross-sectional shape was It was found that the shape from the top surface was a trapezoidal shape with a substantially trapezoidal shape, the width of the convex portion was 45 nm, and the width of the valley portion was 70 nm.

・ Nickel stamper creation The surface of the resulting resist pattern with a pitch of 145 nm was coated with 30 nm of gold as a conductive treatment by sputtering, then electroplated with nickel, and a nickel stamper having a fine concavo-convex grating with a thickness of 0.3 mm on the surface. It was created.

・ Preparation of lattice-shaped convex transfer film using UV curable resin Apply UV curable resin (Toyo Gosei Co., Ltd. PAK01) about 0.03mm to 0.1mm thick polyethylene terephthalate resin film (hereinafter referred to as PET film) Then, on the nickel stamper having the fine concavo-convex grating with 145 nm pitch on the surface with the coating surface facing down, it is placed so that air does not enter between the nickel stamper and the PET film from each end, and the center from the PET film side. Ultraviolet rays were irradiated at 1000 mJ / cm ² using an ultraviolet lamp having a wavelength of 365 nm to transfer the fine uneven grating of the nickel stamper. The obtained lattice-like convex transfer film was observed by STEM, and it was confirmed that the cross-sectional shape was substantially trapezoidal and the shape from the upper surface was a striped lattice.

-Creation of reflection type wire grid polarizer The dielectric material was coat | covered using the sputtering method to the lattice-shaped convex-part transfer film created using the above-mentioned ultraviolet curable resin. In this embodiment, a case where silicon nitride is used as a dielectric will be described. The dielectric was coated at an Ar gas pressure of 0.67 Pa, a sputtering power of 4 W / cm ² , and a coating speed of 0.22 nm / second. As a layer thickness comparison sample, a glass substrate having a smooth surface was inserted into the apparatus at the same time as the lattice-shaped convex transfer film, and film formation was performed so that the dielectric laminate thickness on the smooth glass substrate was 5 nm.

After forming a dielectric layer on the lattice-shaped convex transfer film, a metal wire was formed using an electron beam vacuum deposition method (EB deposition method). In this example, aluminum (Al) was used as the metal. Deposition was performed with a degree of vacuum of 2.5 × 10 ⁻³ Pa, a deposition rate of 20 nm / s, and a substrate temperature of room temperature. As a layer thickness comparison sample, a glass substrate having a smooth surface was inserted into the apparatus simultaneously with the dielectric laminated lattice-shaped convex transfer film, and vapor deposition was performed so that the Al deposition thickness on the smooth substrate was 170 nm. Note that the angle formed by the normal of the substrate surface and the evaporation source in a plane perpendicular to the longitudinal direction of the lattice was 20 degrees.

  After laminating the dielectric and Al on the lattice-shaped convex transfer film, the film is changed in a 0.1 wt% sodium hydroxide aqueous solution at room temperature while changing the treatment time at intervals of 10 seconds between 30 seconds and 120 seconds. Cleaning (etching) was performed, and the etching was stopped immediately by washing with water. The film was dried to obtain a reflective wire grid polarizer. From the following polarization performance evaluation, a reflective wire grid polarizer etched for 90 seconds was selected.

  About the obtained reflection type wire grid polarizer, the transmitted light intensity and reflected light intensity in parallel Nicol and orthogonal Nicol with respect to linearly polarized light were measured using a spectrophotometer. As a result, the TE wave transmittance of the reflective wire grid polarizer is 88.7%, the TM wave transmittance is 0.04%, the TE wave reflectance is 3.4%, the TM wave reflectance is 54.8%, and the degree of polarization is 99. 91%.

-Creation of Absorption Type Wire Grid Polarizer A non-stoichiometric aluminum oxide wire was formed on the lattice-shaped convex transfer film having silicon nitride formed on the surface in the same manner as described above by sputtering. In this example, aluminum (Al) was used for deposition at an Ar gas pressure of 0.145 Pa, an oxygen gas pressure of 0.025 Pa, a target applied voltage of 200 V, and a film formation rate of 40 nm / min. As a layer thickness comparison sample, a glass substrate having a smooth surface was inserted into the apparatus at the same time as the dielectric laminated lattice-shaped convex transfer film, and vapor deposition was performed so that the aluminum oxide deposition thickness on the smooth substrate was 100 nm. Note that the angle formed by the normal of the substrate surface and the evaporation source in a plane perpendicular to the longitudinal direction of the lattice was 30 degrees. The extinction coefficient k of the obtained non-stoichiometric aluminum oxide at 550 nm was 0.36.

  After laminating a dielectric and non-stoichiometric aluminum oxide on the lattice-shaped convex transfer film, the film is placed in a 0.1 wt% aqueous sodium hydroxide solution at room temperature, and the treatment time is 120 seconds to 200 seconds at intervals of 10 seconds. Washing (etching) was performed while changing, and then immediately washing with water to stop the etching. The film was dried to obtain an absorption wire grid polarizer. From the evaluation of polarization performance, an absorption type wire grid polarizer etched for 160 seconds was selected.

  When the obtained absorption wire grid polarizer was observed by STEM, it was confirmed that the non-stoichiometric aluminum oxide wire was formed at a height of 200 nm in the perpendicular direction on one side of the cross-sectional slope of the lattice-like convex portion. It was. Moreover, about the obtained absorption type wire grid type | mold polarizer, the transmitted light intensity | strength and reflected light intensity | strength in parallel Nicol and orthogonal Nicol with respect to linearly polarized light were measured using the spectrophotometer. As a result, the absorption wave grid polarizer has a TE wave transmittance of 89.4%, a TM wave transmittance of 47.5%, a TE wave reflectance of 5.4%, a TM wave reflectance of 7.6%, and a polarization degree of 30. It was 6%.

-Stacking of absorption type and reflection type wire grid polarizers Using the method described above, the polarization axes of the four sides around the obtained absorption type and reflection type wire grid polarizers were aligned with reference to the existing polarizers. . Next, the substrate sides of each wire grid were bonded and laminated using an optically transparent adhesive material while mechanically aligning one side with the polarization axis aligned.

  About the obtained polarizer, the transmitted light intensity with respect to linearly polarized light and the reflected light intensity were measured using the spectrophotometer. TE wave transmittance 81.5%, TM wave transmittance 0.025%, TE wave reflectance 4.3% on the absorption wire grid polarizer side, TM wave reflectance 29.9%, Total light reflectance 17. 1%. The TE wave reflectance on the reflective wire grid polarizer side was 4.3%, the TM wave reflectance was 76.6%, the total light reflectance was 40.5%, and the degree of polarization was 99.93%.

[Example 2]
-Creation of absorption type wire grid polarizer A tungsten wire was formed on a lattice-like convex transfer film having silicon nitride formed on the surface by sputtering as in the example. In this example, deposition was performed by using tangus tungsten (W) at an Ar gas pressure of 0.21 Pa and a target applied voltage of 366 V at a film forming rate of 20 nm / min. As a layer thickness comparison sample, a glass substrate having a smooth surface was inserted into the apparatus simultaneously with the dielectric laminated lattice-shaped convex transfer film, and vapor deposition was performed so that the W deposition thickness on the smooth substrate was 12 nm. The angle formed between the normal of the substrate surface and the vapor deposition source in a plane perpendicular to the longitudinal direction of the lattice was 50 degrees.

  After laminating the dielectric and W on the lattice-shaped convex transfer film, the film is changed in a 0.025 wt% sodium hydroxide aqueous solution at room temperature while changing the treatment time at intervals of 10 seconds between 30 seconds and 100 seconds. Cleaning (etching) was performed, and the etching was stopped immediately by washing with water. The film was dried to obtain an absorption wire grid polarizer. From the evaluation of polarization performance, an absorption wire grid polarizer etched for 50 seconds was selected.

  When the obtained absorption wire grid polarizer was observed by STEM, it was confirmed that the tungsten wire was formed with a thickness of 10 nm on one side of the cross-sectional slope portion of the lattice-like convex portion. Moreover, about the obtained absorption type wire grid type | mold polarizer, the transmitted light intensity | strength and reflected light intensity | strength in parallel Nicol and orthogonal Nicol with respect to linearly polarized light were measured using the spectrophotometer. As a result, the absorption wave grid polarizer has a TE wave transmittance of 91.6%, a TM wave transmittance of 23.2%, a TE wave reflectance of 3.8%, a TM wave reflectance of 12.0%, and a polarization degree of 59. 56%.

-Lamination | stacking of absorption type and reflection type wire grid polarizer Using the reflection type wire grid polarizer used in Example 1, adhesion lamination was carried out by the same method as Example 1. About the obtained polarizer, the transmitted light intensity with respect to linearly polarized light and the reflected light intensity were measured using the spectrophotometer. TE wave transmittance 79.25%, TM wave transmittance 0.012%, TE wave reflectance 4.2% on the absorption wire grid polarizer side, TM wave reflectance 17.1%, Total light reflectance 10. 7%. The TE wave reflectance on the reflective wire grid polarizer side was 4.9%, the TM wave reflectance was 77.8%, the total light reflectance was 41.4%, and the degree of polarization was 99.97%.

[Example 3]
・ Preparation of lattice-shaped convex transfer film using UV curable resin Apply UV curable resin (Toyo Gosei Co., Ltd. PAK01) about 0.03mm to 0.1mm thick polyethylene terephthalate resin film (hereinafter referred to as PET film) Then, on the nickel stamper having the fine concavo-convex grating with 145 nm pitch on the surface with the coating surface facing down, it is placed so that air does not enter between the nickel stamper and the PET film from each end, and the center from the PET film side. Ultraviolet rays were irradiated at 1000 mJ / cm ² using an ultraviolet lamp having a wavelength of 365 nm to transfer the fine uneven grating of the nickel stamper. Thereafter, the substrate was rotated 180 degrees on a rotation axis parallel to the fine concavo-convex grid of the nickel stamper, and the fine concavo-convex grid of the nickel stamper was similarly transferred to the back side. The front and back surfaces of the obtained grid-like convex transfer film were observed by FE-SEM, and each cross-sectional shape was substantially trapezoidal, and the shape from the top surface was a striped grid shape and the grids were parallel to each other. I confirmed that there was.

-Preparation of reflective wire grid polarizer After forming silicon nitride on one side of the front and back grid-like convex transfer film in the same manner as in Example 1, aluminum wires were formed by vacuum deposition. Thereafter, the film was washed (etched) in a 0.1 wt% sodium hydroxide aqueous solution at room temperature while changing the treatment time at intervals of 10 seconds between 30 seconds and 120 seconds, and immediately washed with water to stop the etching. I let you. The film was dried to obtain a reflective wire grid polarizer. From the evaluation of polarization performance, a reflective wire grid polarizer that was etched for 80 seconds was selected.

  About the obtained reflection type wire grid polarizer, the transmitted light intensity and reflected light intensity in parallel Nicol and orthogonal Nicol with respect to linearly polarized light were measured using a spectrophotometer. As a result, the TE wave transmittance of the reflective wire grid polarizer is 85.3%, the TM wave transmittance is 0.038%, the TE wave reflectance is 3.4%, the TM wave reflectance is 58.9%, and the degree of polarization is 99. It was 91%.

  Next, silicon nitride was formed on the back surface of the reflective wire grid polarizer in the same manner as in Example 1, and then a tungsten wire was formed under the same conditions as in Example 2. After laminating the tungsten wire, the film was washed (etched) in 0.025 wt% sodium hydroxide aqueous solution at room temperature while changing the treatment time at intervals of 2 seconds between 5 seconds and 30 seconds, and immediately washed with water. Then, the etching was stopped. The film was dried to obtain a polarizer having a reflective wire grid polarizer formed on one side and an absorptive wire grid polarizer formed on the back side.

  About the obtained polarizer, the transmitted light intensity with respect to linearly polarized light and the reflected light intensity were measured using the spectrophotometer. TE wave transmittance 80.1%, TM wave transmittance 0.011%, TE wave reflectance 4.1% on the absorption wire grid polarizer side, TM wave reflectance 18.4%, Total light reflectance 11. 3%. The TE wave reflectance on the reflective wire grid polarizer side was 4.2%, the TM wave reflectance was 79.9%, the total light reflectance was 42.1%, and the degree of polarization was 99.97%.

  As described above, the wire grid polarizer according to the present invention has a simple configuration, efficiently absorbs external light, and has high light utilization efficiency due to high reflectivity on the backlight side. When it is disposed in the position, sufficient color reproducibility and black display can be realized. Since the expression of the polarization function is entirely composed of an inorganic material, it has excellent durability.

1 is a schematic cross-sectional perspective view of a wire grid polarizer according to an embodiment of the present invention. 1 is an enlarged schematic cross-sectional perspective view of an absorption wire grid polarizer constituting the present invention. It is the general | schematic cross-section perspective view which expanded and illustrated an example of the other structure of the absorption type wire grid polarizer which comprises this invention. 1 is an enlarged schematic cross-sectional perspective view of a reflective wire grid polarizer constituting the present invention. It is the schematic which shows an example of the adhesion process for comprising the wire grid polarizer of this invention. It is a schematic cross-sectional perspective view which shows an example of the other structure of the wire grid polarizer which concerns on embodiment of this invention. It is a schematic sectional perspective view which shows an example of the base material which comprises this invention. It is a cross-sectional schematic diagram which shows the liquid crystal display device using the polarizer which concerns on embodiment of this invention.

Explanation of symbols

1,11, 21b, 22b Absorption-type wire grid polarizer 1a, 1d Absorption-type polarization component wire 1a-t Height of absorption-type polarization component wire in the perpendicular direction 1b, 2b, 8 Substrate 1c, 2c Grid-shaped convex part 1d Absorption type polarization component wire 2, 21a, 22a Reflection type wire grid polarizer 2a Metal wire 3, 21, 22 Wire grid polarizer 4, 5 Incident light 7 Adhesive layer 10 Polarization axis 11a Side coincident with polarization axis 12 Polarizer 20 Illumination device 23 Liquid crystal cell 30 Backlight incident light 31 Outside light incident light

Claims (6)

  A composite of an absorptive wire grid polarizer in which an absorptive polarization component is arranged in a lattice on a substrate and a reflective wire grid polarizer in which a reflective polarization component is arranged in a lattice on a substrate Wire grid polarizer, at least the absorption wire grid polarizer is a layer composed of a base material having convex portions in a lattice shape and an absorbing polarization component formed on the convex portions of the base material And a wire grid polarizer.   2. The wire grid polarizer according to claim 1, wherein the layer is formed only on one side of a cross-sectional slope portion of the lattice-like convex portion of the base material.   The layer is a layer made of an oxide selected from the group consisting of aluminum oxide, iron oxide, nickel oxide, copper oxide, vanadium oxide and chromium oxide, and the perpendicular direction from the lattice-like convex portion of the base material The wire grid polarizer according to claim 1, wherein the height of the wire grid polarizer is 8 nm or more and 250 nm or less.   The layer is selected from the group consisting of W, V, Cr, Co, Mo, Ge, Ir, Ni, Os, Ti, Fe, Nb, Hf, Mn, Ta and alloys containing at least one of them as a main component. 3. The wire grid polarizer according to claim 1, wherein the wire grid polarizer is made of at least one metal and has a thickness of 5 nm to 30 nm.   The reflective wire grid polarizer includes a base material having convex portions in a lattice shape, and a layer composed of a reflective polarization component formed on the convex portions of the base material. The wire grid polarizer in any one of Claims 1-4.   A display device, an illuminating unit that irradiates light to the display device, and the wire grid polarizer according to any one of claims 1 to 5, wherein the reflective wire grid polarizer is the illuminating unit. A display device arranged on the side.

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