Vehicle, projection display device, and polarization beam splitter

Abstract

To provide a vehicle and a projection display device including a polarization beam splitter excellent in heat dissipation as well as excellent in polarization separation characteristic and transmissivity to oblique incident light at wide-range incident angles.SOLUTION: A vehicle includes a projection display device. The projection display device includes a light source 210, a polarization beam splitter 230, a reflection type liquid crystal display element 240, and a lens 250. The polarization beam splitter 230 includes a wire grid polarizing element 1. The wire grid polarizing element 1 of a hybrid type including an inorganic material and an organic material includes a substrate 10 formed of an inorganic material, a grid structure 20 formed of an organic material in which a base part 21 and a plurality of projecting parts 22 provided on the substrate 10 are integrated, and a functional film 30 made of a metal material and covering a part of the projecting parts 22.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to a wire-grid polarizing element that has good polarization characteristics, does not deteriorate heat dissipation characteristics or manufacturing costs, and has excellent transmittance for obliquely incident light and light incident at a wide range of incident angles, a method for manufacturing a wire-grid polarizing element, and a projection display device that has excellent polarization characteristics and heat resistance, and a vehicle equipped with the projection display device. [Background technology]

[0002] As one type of projection display device, many head-up display devices for vehicles have been developed in recent years, which display images on semi-transparent plates (hereinafter collectively referred to as "display surfaces") such as the windshield or combiner of the vehicle. A head-up display device for vehicles is, for example, an image display device that is disposed on the dashboard of the vehicle, projects image light onto the windshield, and displays driving information as a virtual image. Since the driver can simultaneously view the virtual image and the scenery through the windshield, this has the advantage of reducing the movement of the driver's line of sight compared to conventional display devices such as liquid crystal displays that are installed outside the range of the windshield.

[0003] However, because the above-mentioned head-up display device emits a display image from below toward the windshield surface (upward), sunlight can enter in the opposite direction to the emission direction of the display image and enter the display element. In many head-up display devices, a reflector is provided to reflect and enlarge the display image in order to meet the demands for miniaturization and to enlarge the display image. In such cases, sunlight entering the head-up display device is concentrated near the display element, and there is a risk that heat will cause deterioration or failure of the display element.

[0004] Therefore, a technology has been developed to provide a reflective polarizing element in a head-up display device in order to prevent sunlight from entering the display element. For example, Patent Document 1 discloses a head-up display device in which a reflective polarizing element (wire grid polarizer) is provided between a reflector and a display element.

[0005] Here, examples of the polarizing element provided in the head-up display device as described above include a polarizing element made of a birefringent resin, a wire-grid type polarizing element in which a plurality of conductors (thin metal wires) extend in parallel on a transparent substrate, and a polarizing element made of cholesteric phase liquid crystal. Among these, a wire-grid type polarizing element having excellent polarization characteristics is often used. In a wire-grid type polarizing element, a wire grid is formed in which conductor wires made of metal or the like are arranged in a lattice shape at a specific pitch. By setting the arrangement pitch of the wire grid to a pitch smaller (e.g., half or less) than the wavelength of the incident light (e.g., visible light), it is possible to reflect most of the light of the electric field vector component oscillating parallel to the conductor wire and transmit most of the light of the electric field vector component perpendicular to the conductor wire. As a result, the wire-grid type polarizing element can be used as a polarizing element that creates a single polarized light, and can reflect and reuse the light that is not transmitted, which is desirable from the viewpoint of effective use of light. The polarizing element referred to here includes a polarizing element that can be used as a polarizing beam splitter that separates incident light into S-polarized light and P-polarized light.

[0006] As an example of such a wire-grid polarizing element, Patent Document 2 discloses a wire-grid polarizing plate including a resin substrate having grid-shaped protrusions, a dielectric layer provided so as to cover the grid-shaped protrusions of the resin substrate, and metal wires provided on the dielectric layer.

[0007] Patent Document 3 discloses a wire grid polarizer having a substrate made of a resin or the like and having a concave-convex structure extending in a specific direction on its surface, and a conductor provided so as to be unevenly distributed on one side of the convex portions of the concave-convex structure. In this wire grid polarizer, the pitch between two adjacent convex portions and the height of the convex portions are adjusted in a cross-sectional view perpendicular to the extending direction of the concave-convex structure.

[0008] Furthermore, Patent Document 4 discloses a projection type image display device using a reflective liquid crystal display element and a reflective wire grid polarizer as a polarizing beam splitter. In the projection type image display device using the reflective liquid crystal display element described in Patent Document 4, the reflective wire grid polarizer is disposed at an angle of about 45° to the optical axis of light emitted from a light source. The light emitted from the light source is separated into a first polarized light (reflected light) and a second polarized light (transmitted light) by entering the reflective wire grid at an incident angle of about 45°. The first polarized light reflected by the reflective wire grid polarizer is then modulated and reflected by the reflective liquid crystal display element to become the second polarized light, and the second polarized light is transmitted through the reflective wire grid polarizer to be projected and displayed.

[0009] Patent Document 5 discloses a vehicle headlamp that uses a reflective wire grid polarizer as a polarizing beam splitter. In the vehicle headlamp described in Patent Document 5, the reflective wire grid polarizer is also disposed at an angle of about 45° to the optical axis of light emitted from a light source. When light emitted from the light source enters the reflective wire grid at an incident angle of about 45°, the light is separated into a first polarized light (reflected light) and a second polarized light (transmitted light).

[0010] When a reflective wire-grid polarizer is positioned at an angle of approximately 45° to the light emitted from a light source, such as in the projection type image display device described in Patent Document 4 and the vehicle headlamp described in Patent Document 5, the incident light does not only enter the reflective wire-grid polarizer at a single incident angle of 45°, but also at an incident angle in the range of approximately 45°±15°.

[0011] Furthermore, Patent Document 6 discloses a wire grid polarization beam splitter in which a plurality of grids made entirely of silver or aluminum are formed to protrude from a substrate.

[0012] Patent Document 7 discloses a wire-grid polarizer having a light-transmitting substrate, an underlayer, and thin metal wires. In the wire-grid polarizer of Patent Document 7, the light-transmitting substrate has a surface on which a plurality of parallel protrusions are formed at a predetermined pitch. The underlayer is made of a metal oxide present at least on the apexes of the protrusions, and the thin metal wires are made of a metal layer present on the surface of the underlayer and at least on the apexes of the protrusions. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2018-72507 A [Patent Document 2] JP 2008-83657 A [Patent Document 3] JP 2017-173832 A [Patent Document 4] JP 2004-184889 A [Patent Document 5] JP 2019-50134 A [Patent Document 6] Special Publication No. 2003-508813 [Patent Document 7] International Publication No. 2010 / 005059 Summary of the Invention [Problem to be solved by the invention]

[0014] Generally, the temperature environment required for devices used in vehicles is -40 to 105°C. However, when considering use in a high temperature environment, such as a head-up display mounted on a dashboard in a vehicle in summer, high heat resistance and heat dissipation are required. In this regard, the wire grid polarizers described in Patent Documents 1 to 3 are required to be further improved in terms of heat resistance and heat dissipation. In addition, in order to brightly illuminate the road at night with the vehicle headlight described in Patent Document 5, it is essential to increase the brightness of the vehicle headlight. For this reason, the wire grid polarizer described in Patent Document 5 is required to have high heat resistance and heat dissipation against heat from a light source.

[0015] Furthermore, conventional wire grid polarizers have problems such as high manufacturing costs and being unsuitable for mass production because the uneven surface shape is generally formed by photolithography or etching techniques.

[0016] In a projection display device such as a head-up display device, when a reflective wire grid polarizer is used as a polarizing beam splitter to separate a first polarized light (S polarized light) and a second polarized light (P polarized light), both the reflectance of the first polarized light and the transmittance of the second polarized light are required to be high. Here, when the product (Tp×Rs) of the reflection axis reflectance (Rs) of the first polarized light (S polarized light) and the transmission axis transmittance (Tp) of the second polarized light (P polarized light) is used as an index of the polarization separation characteristics, it is preferable that the value of Tp×Rs is high. However, depending on the type of projection display device to which the polarizing beam splitter is applied, the handling of polarized light in the polarizing beam splitter differs, and there are cases where the first polarized light (S polarized light) becomes a transmitted light and the second polarized light (P polarized light) becomes a reflected light.

[0017] In addition, the angle of incidence of light incident on the polarizing beam splitter is not limited to a single angle of 45°, but extends over a range of approximately 45°±15° centered on 45°, so that light at a wide range of incidence angles is incident on the polarizing beam splitter. For this reason, a polarizing beam splitter is also required to exhibit good polarization separation characteristics for obliquely incident light, regardless of the angle of incidence of the light incident from an oblique direction (hereinafter referred to as obliquely incident light).

[0018] However, in the case of the structure of the conventional reflective wire-grid polarizer, as the incidence angle of the obliquely incident light increases, the transmission axis transmittance (Tp) of the second polarized light (P polarized light) decreases, and the polarization separation characteristics for the obliquely incident light decrease. For example, consider the case where the entire convex portion of the grid is made of a conductor as described in Patent Document 6, or the case where a conductor (reflective film) is provided unevenly distributed on the entire one side surface of the convex portion of the wire grid as described in Patent Document 3. In these cases, as the incidence angle of the obliquely incident light increases, the transmission axis transmittance (Tp) of the second polarized light (P polarized light) decreases, and the above Tp×Rs decreases. This causes a deterioration in the light utilization efficiency, and a deterioration in image quality such as uneven brightness has become a problem. Therefore, in the structure of the conventional reflective wire-grid polarizer described in Patent Documents 3, 6, etc., there is room for improvement in the polarization separation characteristics for obliquely incident light with a large and wide range of incidence angles.

[0019] Patent Document 7 also describes that the coverage of the side surfaces of the convex stripes with the metal layer (reflective film) is 50% or more, preferably 70% or more, and particularly preferably 100%. Patent Document 7 further describes that as the area of ​​the metal layer covering the side surfaces of the convex stripes becomes larger, a lower S-polarized light reflectance can be achieved for light incident from the back surface side of the wire-grid polarizer, and S-polarized light incident from the front surface side can be efficiently reflected, resulting in the wire-grid polarizer exhibiting high polarization separation ability.

[0020] However, when the area of ​​the metal layer covering the side surfaces of the convex stripes of the wire grid is large as described in Patent Document 7, when the angle of incidence of obliquely incident light is large, particularly 45 to 60°, the transmission axis transmittance (Tp) of the second polarized light (P polarized light) is significantly reduced, and the above Tp×Rs is also significantly reduced. This results in a deterioration in light utilization efficiency, and problems with reduced image quality such as uneven brightness. Therefore, even with the structure of the wire grid polarizer described in Patent Document 7, there is still room for improvement in the polarization separation characteristics for obliquely incident light with a large and wide range of incident angles.

[0021] As described above, it is desirable to have excellent polarization separation characteristics for obliquely incident light over a large and wide range of incident angles. However, conventional reflective wire-grid polarizers are unable to ensure sufficient transmittance for light over a wide range of incident angles, particularly for light with large incident angles of 45° or more. Therefore, further improvements in the transmittance and polarization separation characteristics for obliquely incident light are desired.

[0022] Therefore, the present invention has been made in consideration of the above circumstances, and aims to provide a vehicle and a projection display device equipped with a polarizing beam splitter that has excellent heat dissipation properties, as well as excellent transmittance and polarization separation characteristics for obliquely incident light over a wide range of incident angles. [Means for solving the problem]

[0023] The present inventors conducted extensive research to solve the above problems and came to the following conclusion. First, the substrate of the wire-grid polarizer is made of a transparent inorganic material, and the grid structure provided on the substrate is integrally formed of a transparent organic material. This makes it possible to give the wire-grid polarizer a hybrid structure made of organic and inorganic materials. As a result, the heat dissipation properties of the wire-grid polarizer can be significantly improved.

[0024] Furthermore, the grid structure is formed by integrally forming a base portion provided along the surface of the substrate and a plurality of ridge portions protruding from the base portion, and can be formed by a technique such as nanoimprinting, thereby reducing the manufacturing cost of the grid structure and enabling mass production, as compared to the case where photolithography or etching techniques are used.

[0025] Furthermore, when a functional film, such as a reflective film that reflects light or an absorbing film that absorbs light, is provided on the convex rib portions of the grid structure, the coverage and coverage form of the convex rib portions by the functional film are suitably adjusted. That is, the tip of the convex rib portion and the upper side of one or both sides are covered by the functional film in a wrapping manner, while the lower side of the side of the convex rib portion and the surface of the base portion are left open without being covered by the functional film. The functional film is then rounded and shaped to bulge in the width direction of the convex rib portion, wrapping around the tip and the upper side of the side of the convex rib portion. Furthermore, the maximum width (W MAX ) is the width of the bottom of the convex part (W B The shape and size of the ridges and the functional film are adjusted so that the height (H) of the ridges is at least 100 mm. Furthermore, it is preferable to limit the area of ​​the functional film covering the side surface of the ridges to a specific area on the upper side of the side surface (for example, a range of 25% to 80% of the height (H) of the ridges).

[0026] As a result, even when obliquely incident light having a large and wide range of incident angles is incident on the wire grid polarization element, the transmittance (Tp) of the second polarized light (P polarized light) in the wire grid polarization element can be prevented from decreasing depending on the incident angle. Therefore, the product (Tp x Rs) of the reflection axis reflectance (Rs) of the first polarized light (S polarized light) and the transmission axis transmittance (Tp) of the second polarized light (P polarized light) in the wire grid polarization element can be maintained at a high value. Therefore, when the wire grid polarization element is used as, for example, a polarizing beam splitter, sufficient transmittance and polarization separation characteristics can be obtained even for obliquely incident light having a large incident angle and a wide range.

[0027] Based on the above findings, the present inventors have arrived at the following invention.

[0028] In order to solve the above problems, according to one aspect of the present invention, A vehicle equipped with a projection display device, The projection display device includes: A light source; a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle of 30° or more and 60° or less, and splitting the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element that is disposed so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident thereon, and that reflects and modulates the incident first polarized light or the incident second polarized light; a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter; Equipped with the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A hybrid wire grid polarizer made of inorganic and organic materials, A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip of the protruding portion and an upper side of at least one of the side surfaces, but does not cover the lower sides of both side surfaces of the protruding portion and the base portion; The surface of the functional film that covers the convex ridge portion is rounded and bulges in the width direction of the convex ridge portion, and the maximum width (W MAX ) is the width (W) of the convex portion at a position 20% above the height of the convex portion from the bottom of the convex portion B ) or more, a vehicle is provided.

[0029] When the coverage rate (Rc) of the side surface of the protruding portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the protruding portion covered by the functional film to the height (H) of the protruding portion, The coverage (Rc) may be set to be equal to or greater than 25% and equal to or less than 80%.

[0030] The coverage (Rc) may be set to be equal to or greater than 30% and equal to or less than 70%.

[0031] The product (Tp×Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of light incident on the wire grid polarizer at an incident angle of 45° may be 70% or more.

[0032] The height (H) of the convex ridges may be 160 nm or more.

[0033] The functional film covering the tip of the protruding portion may have a thickness (Dt) of 5 nm or more.

[0034] The functional film covering the side surfaces of the protruding ridges may have a thickness (Ds) of 10 nm or more and 30 nm or less.

[0035] The base portion may have a thickness (TB) of 1 nm or more.

[0036] The cross-sectional shape of the protrusions in a cross section perpendicular to the reflection axis direction of the wire-grid polarizer may be a trapezoid, a triangle, a bell shape, or an ellipse whose width narrows with increasing distance from the base portion.

[0037] The display device may further include a protective film formed so as to cover at least the surface of the functional film.

[0038] The protective coating may include a water-repellent or oil-repellent coating.

[0039] The functional film may further include a dielectric film.

[0040] When θ is 30° or more and 60° or less, The difference between the transmission axis transmittance (Tp(+)) of incident light having an incident angle of +θ to the wire grid polarizer and the transmission axis transmittance (Tp(-)) of incident light having an incident angle of -θ may be within 3%.

[0041] The functional film may be a reflective film that reflects incident light.

[0042] The wire grid polarizer may be a polarizing beam splitter that splits obliquely incident light into a first polarized light and a second polarized light.

[0043] In order to solve the above problems, according to another aspect of the present invention, A method for manufacturing a hybrid wire grid polarizer made of inorganic and organic materials, comprising the steps of: forming a grid structure material made of an organic material on a substrate made of an inorganic material; forming a grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed by performing nanoimprinting on the grid structure material; forming a functional film by using a metal material to cover a part of the protruding portion; Including, In the step of forming the grid structure, the protruding portion is formed to have a tapered shape in which the width decreases with increasing distance from the base portion, In the step of forming the functional film, The functional film covers the tip of the convex rib portion and the upper side of at least one of the side surfaces, and does not cover the lower sides of both sides of the convex rib portion and the base portion. The surface of the functional film that covers the convex rib portion is rounded and bulges in the width direction of the convex rib portion, and the maximum width (W MAX ) is the width (W B The present invention provides a method for manufacturing a wire-grid polarizer, in which the functional film is formed so as to satisfy the above-mentioned requirements.

[0044] In the step of forming the functional film, films may be formed alternately from a plurality of directions on the protruding portion by sputtering or vapor deposition.

[0045] In order to solve the above problems, according to another aspect of the present invention, A light source; a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle in a predetermined range including 45°, and splitting the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element that is disposed so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident thereon, and that reflects and modulates the incident first polarized light or the incident second polarized light; a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter; Equipped with the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and upper sides of both sides of the protruding rib portion, but does not cover the lower sides of both sides of the protruding rib portion or the base portion; The surface of the functional film that covers the protruding portion is rounded and bulges in the width direction of the protruding portion, The cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film has a constricted portion in which the width in the width direction of the entire convex structure is narrowed immediately below the lower end of the functional film that covers the convex streak portion, When the coverage rate (Rc) of the side surface of the protruding portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the protruding portion covered by the functional film to the height (H) of the protruding portion, There is provided a projection display device, wherein the coverage (Rc) is 30% or more and 70% or less.

[0046] The predetermined range of incident angles may be equal to or greater than 30° and equal to or less than 60°.

[0047] A heat dissipation member may be provided around the wire grid polarizer.

[0048] In order to solve the above problems, according to another aspect of the present invention, A polarizing beam splitter provided in a projection display device, comprising: the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and upper sides of both sides of the protruding rib portion, but does not cover the lower sides of both sides of the protruding rib portion or the base portion; The surface of the functional film that covers the protruding portion is rounded and bulges in the width direction of the protruding portion, The cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film has a constricted portion in which the width in the width direction of the entire convex structure is narrowed immediately below the lower end of the functional film that covers the convex streak portion, When the coverage rate (Rc) of the side surface of the protruding portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the protruding portion covered by the functional film to the height (H) of the protruding portion, There is provided a polarizing beam splitter, wherein the coverage (Rc) is 30% or more and 70% or less. Effect of the Invention

[0049] According to the present invention, it is possible to provide a vehicle and a projection display device equipped with a polarizing beam splitter that has excellent heat dissipation properties and has excellent polarization separation characteristics for obliquely incident light over a wide range of incident angles. [Brief description of the drawings]

[0050] [Figure 1] 1 is a cross-sectional view illustrating a wire grid polarizer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view illustrating a wire-grid polarizer according to the embodiment. [Diagram 3] 10A and 10B are cross-sectional views each showing a schematic example of a tapered shape of a protruding portion of the grid structure according to the embodiment. [Figure 4] 5A to 5C are cross-sectional views each showing a schematic example of a shape of a recess of the grid structure according to the embodiment. [Diagram 5] FIG. 2 is a cross-sectional view illustrating a wire-grid polarizer according to the embodiment. [Figure 6] 4A to 4C are cross-sectional views illustrating schematic examples of shapes of the reflective film according to the embodiment. [Figure 7] FIG. 2 is a cross-sectional view illustrating a polarizing element covered with a protective film according to the embodiment. [Figure 8] 13 is a cross-sectional view showing a schematic diagram of a modified example of a polarizing element covered with a protective film according to the embodiment. FIG. [Figure 9] FIG. 2 is a perspective view illustrating a polarizing element including a heat dissipation member according to the embodiment. [Figure 10] 13 is a photograph showing an actual grid structure and a reflective film according to the embodiment. [Figure 11] 5A to 5C are process diagrams showing a method for manufacturing a wire-grid polarizer according to the embodiment. [Figure 12] 1A to 1C are process diagrams showing a conventional method for manufacturing a wire-grid polarizer. [Figure 13] 5A to 5C are process diagrams showing a method for manufacturing a master according to the embodiment. [Figure 14] 2 is a schematic diagram showing a head-up display device as an example of a projection display device according to the embodiment. FIG. [Figure 15] FIG. 2 is a schematic diagram showing a first specific example of a projection display device according to the embodiment. [Figure 16] 4 is a schematic diagram showing a second specific example of the projection display device according to the embodiment. FIG. [Figure 17] FIG. 11 is a schematic diagram showing a third specific example of the projection display device according to the embodiment. [Figure 18] FIG. 1 is a diagram for explaining a polarizing element according to Conventional Example 1. [Figure 19] FIG. 13 is a diagram for explaining a polarizing element according to Conventional Example 2. [Figure 20] FIG. 11 is a diagram for explaining a polarizing element according to Conventional Example 3. [Figure 21] FIG. 2 is a diagram for explaining a polarizing element according to the first embodiment. [Figure 22] FIG. 13 is a diagram for explaining a comparison result between Example 1 and Conventional Example 2. [Figure 23] 11 is a diagram for explaining a polarizing element according to Example 2. FIG. [Figure 24] 11 is a diagram for explaining a polarizing element according to Example 3. FIG. [Diagram 25] 11 is a diagram for explaining a polarizing element according to Example 4. FIG. [Figure 26] 13 is a diagram for explaining a polarizing element according to Example 5. FIG. [Figure 27] 13 is a diagram for explaining a polarizing element according to Example 6. FIG. [Figure 28] 13 is a diagram for explaining a polarizing element according to Example 7. FIG. [Figure 29] 13 is a diagram for explaining a polarizing element according to Example 8. FIG. [Diagram 30] FIG. 13 is a diagram for explaining a comparison result between Example 9 and Conventional Example 4. [Diagram 31] FIG. 13 is a diagram for explaining the results of a comparison between Example 9 and Conventional Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals to avoid repetitive description. For convenience of explanation, the state of each member disclosed in the following drawings may be shown diagrammatically at a scale and in a shape different from the actual state.

[0052] <1. Overview of wire grid polarizer> First, an overview of a wire grid polarizer 1 according to an embodiment of the present invention will be described with reference to Fig. 1, Fig. 2, etc. Fig. 1 is a cross-sectional view that typically shows the wire grid polarizer 1 according to this embodiment. Fig. 2 is a plan view that typically shows the wire grid polarizer 1 according to this embodiment.

[0053] The wire grid polarizer 1 according to the present embodiment is a reflective polarizer and a wire grid type polarizer. The wire grid polarizer 1 may be, for example, a plate-shaped wire grid polarizer. The wire grid polarizer is a plate-shaped wire grid type polarizer. The wire grid polarizer may be, for example, a flat plate or a curved plate. That is, the surface (the surface on which light is incident) of the wire grid polarizer 1 may be a flat surface or a curved surface. In the following, an example in which the wire grid polarizer 1 according to the present embodiment is a flat wire grid polarizer will be described, but the wire grid polarizer of the present invention is not limited to such an example and may have any shape depending on its application, function, and the like.

[0054] The wire grid polarization element of the present invention may be used, for example, as a polarizer that transmits only light vibrating in one specific direction, or as a polarizing beam splitter that splits incident light into a first polarized light (S polarized light) and a second polarized light (P polarized light). The following mainly describes an example in which the wire grid polarization element 1 according to this embodiment is used as a polarizing beam splitter.

[0055] As shown in Figures 1 and 2, the wire-grid polarizing element 1 (hereinafter sometimes abbreviated as "polarizing element 1") comprises a transparent substrate 10, a transparent grid structure 20, and an opaque functional film (e.g., a reflective film 30).

[0056] In this specification, "transparent" means that the transmittance of light of wavelength λ belonging to the used band (for example, the visible light band, the infrared light band, or the visible light and infrared light bands, etc.) is high, for example, the transmittance of the light is 70% or more. The wavelength band of visible light is, for example, 360 nm or more and 830 nm or less. The wavelength band of infrared light (infrared light) is larger than the wavelength band of visible light, for example, 830 nm or more. From the viewpoint of a suitable wavelength range of visible light projected as a display image, the wavelength λ of the used band in the polarizing element 1 according to this embodiment is, for example, preferably 400 nm or more and 800 nm or less, and more preferably 420 nm or more and 680 nm or less. The polarizing element 1 according to this embodiment is formed of a material transparent to the light of the used band, so that it does not adversely affect the polarization characteristics, light transmittance, etc. of the polarizing element 1.

[0057] The substrate 10 is made of a transparent inorganic material such as glass, etc. The substrate 10 is a flat substrate having a predetermined thickness TS.

[0058] The grid structure 20 is made of a transparent organic material, for example, an organic resin material such as an ultraviolet-curable resin or a thermosetting resin having excellent heat resistance. The grid structure 20 has a concave-convex structure for realizing the polarization function of the polarizing element 1. Specifically, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10, and a plurality of convex streaks 22 protruding from the base portion 21 in a grid pattern. The base portion 21 and the plurality of convex streaks 22 of the grid structure 20 are integrally formed using the same organic material.

[0059] The base portion 21 is a thin film having a predetermined thickness TB, and is laminated over the entire main surface of the substrate 10 (the XY plane shown in FIGS. 1 and 2). The thickness TB of the base portion 21 is preferably substantially the same over the entire main surface of the substrate 10, but it does not have to be exactly the same thickness, and may vary with a certain degree of error from the reference thickness of TB. For example, TB may vary by about ±3 μm from the reference thickness of 6 μm. In this way, the thickness TB of the base portion 21 is determined by allowing for molding errors when molding the base portion 21 by imprinting or the like.

[0060] The multiple convex streaks 22 are arranged on the base portion 21 at equal intervals in the X direction at a predetermined pitch P. The pitch P is the spacing between the multiple convex streaks 22 arranged in the X direction of the polarizing element 1. The multiple convex streaks 22 are arranged in a lattice pattern so as to extend parallel to each other in the Y direction. A predetermined gap is formed between two adjacent convex streaks 22 in the X direction. This gap serves as a path for incident light to enter. Each convex streaks 22 is a wall-like protrusion formed to protrude and extend in a predetermined direction (the Y direction shown in Figures 1 and 2). The height (H) in the Z direction and the width (W) in the X direction of the multiple convex streaks 22 are T , W B ) are substantially identical to each other. The longitudinal direction (Y direction) of the ridge portion 22 is the direction of the reflection axis of the polarizing element 1, and the width direction (X direction) of the ridge portion 22 is the direction of the transmission axis of the polarizing element 1.

[0061] The functional film is a film for imparting a predetermined function to the grid structure 20 of the polarizing element 1. The functional film is made of, for example, an opaque metal material, and is provided so as to cover a part of the convex stripe portion 22 of the grid structure 20. The functional film may be, for example, a reflective film 30 having a function of reflecting incident light incident on the polarizing element 1, or an absorbing film (not shown) having a function of absorbing the incident light, or a film having other functions. In this embodiment, an example in which the functional film is the reflective film 30 will be described, but the functional film of the present invention is not limited to the example of the reflective film 30.

[0062] The reflective film 30 is a thin film made of a metal material (metal or metal oxide, etc.) such as aluminum or silver. The reflective film 30 is formed so as to cover at least the tops of the protruding stripes 22. The reflective film 30 may be made of a metal film that functions as the thin metal wires of the wire grid. The reflective film 30 has the function of reflecting incident light that is incident on the grid structure 20.

[0063] The convex stripes 22 of the grid structure 20 and the reflective film 30 form a grid of the wire-grid polarizing element 1. The pitch P in the X direction of the multiple convex stripes 22 in the grid structure 20 (i.e., the arrangement pitch of the grid) is set to a pitch smaller than (e.g., half or less than) the wavelength λ of the incident light (e.g., visible light). This allows the polarizing element 1 to reflect most of the light (S-polarized light) whose electric field vector component oscillates in a direction parallel to the reflective film 30 (conductor line) extending in the Y direction (reflection axis direction: Y direction), and transmit most of the light (P-polarized light) whose electric field vector component oscillates in a direction perpendicular to the reflective film 30 (conductor line) (transmission axis direction: X direction).

[0064] As described above, the wire grid polarizer 1 according to this embodiment realizes a polarization function by combining the grid structure 20 having a fine uneven structure with a functional film (e.g., reflective film 30) selectively added to the convex stripes 22 of the grid structure 20. The substrate 10 of the wire grid polarizer 1 is made of an inorganic material such as glass that has excellent heat resistance, and the grid structure 20 is made of an organic resin material that is heat resistant. In this way, the wire grid polarizer 1 according to this embodiment is a hybrid type polarizer that combines organic and inorganic materials. Therefore, the thermal resistance R[m 2 Heat can be efficiently dissipated from the grid structure 20, which has a small [.K / W], to the substrate 10, resulting in excellent heat dissipation. Therefore, the hybrid wire-grid polarizer 1 according to this embodiment has excellent heat resistance and heat dissipation properties compared to conventional film-type polarizers made only of organic materials (heat resistance: approximately 100°C), and has heat resistance in high-temperature environments up to, for example, approximately 200°C. As a result, excellent polarization characteristics can be achieved while maintaining a good heat dissipation effect.

[0065] Furthermore, the wire grid polarizer 1 according to this embodiment may include a protective film 40 (see FIGS. 7 and 8) that covers the surface of the grid structure 20. The protective film 40 is made of an inorganic material, for example, a dielectric material such as SiO2. This protective film 40 may be laminated over the entire surface of the wire grid polarizer 1 so as to cover all of the surfaces of the base portion 21, the protruding stripes 22, and the reflective film 30 of the grid structure 20 (see FIG. 7). Providing such a protective film 40 has the advantageous effect of further reducing the thermal resistance R of the polarizer 1, thereby achieving excellent polarization characteristics while maintaining a better heat dissipation effect.

[0066] As described above, the grid structure 20 in which the base portion 21 and the protruding stripe portion 22 are integrally configured can be manufactured using a printing technique such as nanoimprinting, and a fine uneven structure can be realized by a simple manufacturing process. Therefore, the cost and effort required for manufacturing the grid structure 20 can be reduced compared to manufacturing using photolithography or etching techniques. Therefore, the hybrid type polarizing element 1 according to this embodiment has the advantage that the manufacturing cost can be significantly reduced compared to conventional polarizing elements made only of inorganic materials, and the product unit price of the wire-grid polarizing element 1 can be made inexpensive.

[0067] On the other hand, conventional film-type organic polarizing plates use a large amount of organic materials, and the thickness of the substrate (base film), double-sided tape (OCA: Optically Clear Adhesive), and grid structure are large, so they are considered to have inferior heat dissipation and heat resistance compared to the hybrid-type polarizing element 1 of this embodiment.

[0068] In addition, in the wire grid polarization element 1 according to this embodiment, the grid consisting of the convex stripe portion 22 of the grid structure 20 and the reflective film 30 has a special tree shape (details will be described later) as shown in FIG. 1 and the like. This makes it possible to suppress the transmittance (i.e., transmission axis transmittance Tp) of the second polarized light (P polarized light) passing through the polarization element 1 from decreasing depending on the incidence angle θ of the obliquely incident light, even when the light is incident on the polarization element 1 at a wide range of large incidence angles θ (for example, 30 to 60°). Therefore, the product (Tp×Rs) of the reflectance (i.e., reflection axis reflectance Rs) of the first polarized light (S polarized light) reflected by the wire grid polarization element 1 and the transmission axis transmittance Tp can be maintained at a high value, for example, 70% or more. Therefore, the polarization element 1 according to this embodiment has excellent polarization separation characteristics represented by Tp×Rs, and can polarize obliquely incident light and suitably separate it into S polarized light (reflected light) and P polarized light (transmitted light). Therefore, the polarizing element 1 according to this embodiment can obtain sufficient transmittance and polarization separation characteristics even for obliquely incident light having a large incident angle θ and over a wide range.

[0069] As described above, the wire grid polarizer 1 according to the present embodiment has excellent heat resistance and heat dissipation properties, can reduce manufacturing costs, and has excellent transmittance and polarization separation properties for obliquely incident light with a wide range of large incident angles θ. Therefore, the wire grid polarizer 1 according to the present embodiment can be suitably applied as various components of various products. For example, the polarizer 1 can be applied to a polarizing beam splitter installed in a smart display. The polarizer 1 can also be applied to a polarizing element that is installed in a head-up display (HUD) and is adapted to deal with heat from sunlight, a polarizing element that is adapted to deal with heat from an LED light source, a polarizing reflection mirror, and the like. The polarizer 1 can also be applied to a polarizing beam splitter installed in a headlight such as an adjustable beam distribution headlamp (ADB). The polarizer 1 can also be applied to a lens-integrated phase difference element, a lens-integrated polarizing element, and the like installed in various devices for augmented reality (AR) or virtual reality (VR).

[0070] 2. Components of Wire-Grid Polarizers Next, components of the wire-grid polarizer 1 according to this embodiment will be described in detail with reference to FIGS.

[0071] <2.1. Substrate> 1, a wire-grid polarizer 1 according to this embodiment includes a transparent substrate 10. The substrate 10 is transparent and made of an inorganic material having a certain degree of strength.

[0072] From the viewpoint of obtaining better heat dissipation and heat resistance, the material of the substrate 10 is preferably an inorganic material such as various types of glass, quartz, crystal, sapphire, etc., more preferably an inorganic material with a thermal conductivity of 1.0 W / m·K or more, and even more preferably an inorganic material with a thermal conductivity of 8.0 W / m·K or more.

[0073] The shape of the substrate 10 is not particularly limited and can be appropriately selected depending on the performance required of the polarizing element 1. For example, the substrate 10 can be configured to have a plate shape or a curved surface. In order not to affect the polarization characteristics of the polarizing element 1, the surface of the substrate 10 can be a flat surface. Furthermore, the thickness TS of the substrate 10 is not particularly limited and can be in the range of 0.02 to 10.0 mm, for example.

[0074] <2.2. Grid structure> 1 and 2, the polarizing element 1 according to this embodiment includes a grid structure 20 having a base portion 21 and a lattice-shaped convex stripe portion 22 on a substrate 10. The grid structure 20 can obtain desired polarization characteristics by providing a reflective film 30 (described later) on the convex stripe portion 22.

[0075] When light is incident on the polarizing element 1 from the front surface side on which the grid structure 20 is formed, a part of the incident light is reflected by the reflective film 30. Of the light incident on the reflective film 30, light having an electric field component in a direction perpendicular to the longitudinal direction of the convex streak portion 22 (i.e., the extension direction of the convex streak portion 22 = the reflection axis direction: Y direction) (i.e., the width direction of the convex streak portion 22 = the transmission axis direction: X direction) is transmitted through the polarizing element 1 with high transmittance. On the other hand, of the light incident on the reflective film 30, light having an electric field component in a direction parallel to the longitudinal direction of the convex streak portion 22 (i.e., the extension direction of the convex streak portion 22 = the reflection axis direction: Y direction) is mostly reflected by the reflective film 30. Therefore, in this embodiment, a single polarized light can be created by providing the grid structure 20 partially covered by the reflective film 30. Note that a similar polarization effect can also be obtained for light incident from the rear surface side of the substrate 10.

[0076] As shown in FIG. 1, the grid structure 20 has a base portion 21. The base portion 21 is a thin film provided along the surface of the substrate 10, and is a portion for supporting the convex streak portion 22. When the uneven structure (convex streak portion 22) of the grid structure 20 is formed by nanoimprinting or the like, the base portion 21 is inevitably formed. The base portion 21 and the convex streak portion 22 are integrally formed of the same material. Furthermore, since the grid structure 20 has the base portion 21, the strength of the convex streak portion 22 can be increased compared to when the convex streak portion 22 is formed directly on the substrate 10. This makes it possible to increase the durability of the grid structure 20. Furthermore, since the base portion 21 is in close contact with the substrate 10 over the entire surface, the peel resistance of the grid structure 20 can be increased.

[0077] The thickness TB of the base portion 21 is not particularly limited, but from the viewpoint of more reliably supporting the convex streak portion 22 and from the viewpoint of facilitating imprint molding, it is preferably 1 nm or more, and more preferably 10 nm or more. Moreover, from the viewpoint of ensuring good heat dissipation, the thickness TB of the base portion 21 is preferably 50 μm or less, and more preferably 30 μm or less.

[0078] 1 and 2, the grid structure 20 has a plurality of convex streaks 22 protruding from the base portion 21. The convex streaks 22 extend with the longitudinal direction being the reflection axis direction (Y direction) of the polarizing element 1 according to this embodiment. The multiple convex streaks 22 are arranged at a predetermined pitch in the X direction and at predetermined intervals from each other, thereby forming a lattice-like uneven structure.

[0079] 1, in a longitudinal section (XZ section) perpendicular to the reflection axis direction (Y direction) of the polarizing element 1, the pitch P of the ridges 22 in the transmission axis direction (X direction) must be shorter than the wavelength of light in the band of light used. The reason for this is to obtain the polarization effect described above. More specifically, from the viewpoint of achieving both ease of manufacture of the ridges 22 and polarization characteristics, the pitch P of the ridges 22 is preferably 50 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm.

[0080] As shown in FIG. 1 and FIG. 2, the width W of the bottom of the convex portion 22 in the longitudinal section (XZ section) is B is not particularly limited, but is preferably about 10 to 150 nm, more preferably about 10 to 100 nm, from the viewpoint of compatibility between ease of manufacture and polarization characteristics. T Although there are no particular limitations, from the viewpoint of achieving both ease of production and polarization characteristics, the thickness is preferably about 5 to 60 nm, and more preferably about 10 to 30 nm.

[0081] The width W of the bottom of the protruding portion 22 B and width W of top T can be measured by observing with a scanning electron microscope or a transmission electron microscope. For example, a cross section (XZ cross section) perpendicular to the absorption axis direction or reflection axis direction of the polarizing element 1 is observed using a scanning electron microscope or a transmission electron microscope, and the width of the convex streak portion 22 at any four positions at a height position 20% above the height H of the convex streak portion 22 from the bottom of the convex streak portion 22 is measured, and the arithmetic average value of the widths W of the bottom of the convex streak portion 22 is calculated. B In addition, for any four convex rib portions 22, the width of the convex rib portion 22 is measured at a height position 20% below the height H of the convex rib portion 22 from the tip 22a of the convex rib portion 22, and the arithmetic average value of the widths is defined as the width W of the top of the convex rib portion 22. T It can be said that:

[0082] 1, the height H of the convex ridges 22 in the longitudinal section (XZ section) is not particularly limited, but is preferably about 50 to 350 nm, more preferably about 100 to 300 nm, from the viewpoint of both ease of manufacture and polarization characteristics. The height H of the convex ridges 22 can be measured by observation with a scanning electron microscope or a transmission electron microscope. For example, a cross section perpendicular to the absorption axis direction or reflection axis direction of the polarizing element 1 is observed using a scanning electron microscope or a transmission electron microscope, and the heights of the convex ridges 22 at the center positions in the width direction of the convex ridges 22 at any four positions are measured, and the arithmetic average value of these values ​​can be regarded as the height H of the convex ridges 22.

[0083] The shape of the convex stripes 22 of the grid structure 20 is preferably tapered in order to obtain good polarization separation characteristics for obliquely incident light. Here, the tapered shape refers to a shape in which the width W (the width in the X direction in the XZ cross section) of the convex stripes 22 gradually narrows with increasing distance from the base portion 21, in other words, a shape in which the width W of the convex stripes 22 gradually narrows from the bottom to the top of the convex stripes 22. Therefore, when the convex stripes 22 have a tapered shape, the width W of the top of the convex stripes 22 is T is the width W of the bottom of the protruding portion 22 B becomes smaller (W T <W B ).

[0084] 3 shows a specific example of the tapered shape of the convex streak portion 22 according to this embodiment. As shown in Fig. 3, the cross-sectional shape of the convex streak portion 22 in the above-mentioned longitudinal section (XZ cross section) may be various shapes such as a trapezoid, a triangle, a bell shape, an ellipse, or a rounded wedge shape, in which the width W narrows as it moves away from the base portion 21, so long as it is the above-mentioned tapered shape. For example, the cross-sectional shape of the convex streak portion 22A shown in Fig. 3 is a trapezoid (tapered shape), the cross-sectional shape of the convex streak portion 22B is a triangle, the cross-sectional shape of the convex streak portion 22C is a bell shape, and the cross-sectional shape of the convex streak portion 22D is a wedge shape with rounded top and bottom. In this way, since the convex striate portion 22 has a tapered shape, it is easy to form a reflective film 30 that covers the tip 22a and part of the side surface 22b of the convex striate portion 22, thereby imparting polarization properties to the polarizing element 1. Furthermore, since the tapered shape can also be formed by nanoimprinting, it is advantageous in terms of ease of manufacture.

[0085] In addition, since the convex stripes 22 have a tapered shape, the refractive index of the grid structure 20 changes gradually. Therefore, similar to the moth-eye structure, an anti-reflection effect of incident light due to a change in the physical refractive index of the grid structure 20 is obtained. Therefore, it is possible to reduce the reflectance on the surface of the convex stripes 22 of the grid structure 20, and it is also expected to have the effect of improving the transmittance of the grid structure 20.

[0086] FIG. 4 shows a specific example of the shape of the recess 24 formed between the adjacent ridges 22. The recess 24 is a groove extending in the longitudinal direction (Y direction) of the ridge 22. As shown in FIG. 4, the cross-sectional shape of the recess 24 in the longitudinal section (XZ section) may be various shapes as long as the width becomes narrower toward the bottom of the recess 24. For example, the cross-sectional shape of the recess 24A shown in FIG. 4 is a trapezoid (tapered shape), the cross-sectional shape of the recess 24B is a triangle (V-shaped), the cross-sectional shape of the recess 24C is a substantially rectangular shape with a flat bottom, and the cross-sectional shape of the recess 24D is a U-shaped shape with a rounded bottom. The shape of these recesses 24 can be appropriately selected as an optimal shape in consideration of productivity such as mold releasability during nanoimprint formation.

[0087] Furthermore, the material constituting the grid structure 20 is not particularly limited as long as it is a transparent organic material, and any known organic material can be used. For example, from the viewpoints of ensuring transparency and excellent ease of manufacture, it is preferable to use various types of thermosetting resins, various types of ultraviolet curing resins, etc. as the material for the grid structure 20.

[0088] Furthermore, in terms of ease of manufacture and manufacturing costs, it is preferable that the material constituting the grid structure 20 is different from that of the substrate 10. In addition, when the grid structure 20 and the substrate 10 are made of different materials, the two have different refractive indices. For this reason, if there is an effect on the refractive index of the entire polarizing element 1, a refractive index adjustment layer may be provided between the grid structure 20 and the substrate 10 as appropriate.

[0089] For example, curable resins such as epoxy polymerizable compounds and acrylic polymerizable compounds can be used as materials for forming the grid structure 20. The epoxy polymerizable compounds are monomers, oligomers, or prepolymers having one or more epoxy groups in the molecule. Examples of the epoxy polymerizable compounds include various bisphenol type epoxy resins (bisphenol A type, F type, etc.), novolac type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, stilbene type epoxy resins, triphenolmethane type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and prepolymers thereof.

[0090] The acrylic polymerizable compound is a monomer, oligomer, or prepolymer having one or more acrylic groups in the molecule. Here, the monomer is further classified into a monofunctional monomer having one acrylic group in the molecule, a bifunctional monomer having two acrylic groups in the molecule, and a polyfunctional monomer having three or more acrylic groups in the molecule.

[0091] Examples of "monofunctional monomers" include carboxylic acids (acrylic acid, etc.), hydroxyls (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate), alkyl or alicyclic monomers (isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate), and other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, N,N-dimethylaminoethyl Acrylate, N,N-dimethylaminopropylacrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N,N-diethylacrylamide, 2-(perfluorooctyl)ethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluoro-3-methylbutyl)ethyl acrylate), 2,4,6-tribromophenol acrylate, 2,4,6-tribromophenol methacrylate, 2-(2,4,6-tribromophenoxy)ethyl acrylate), 2-ethylhexyl acrylate, and the like.

[0092] Examples of the "bifunctional monomer" include tri(propylene glycol) diacrylate, trimethylolpropane diallyl ether, and urethane diacrylate. Examples of the "polyfunctional monomer" include trimethylolpropane triacrylate, dipentaerythritol penta- and hexaacrylate, and ditrimethylolpropane tetraacrylate.

[0093] Examples of the acrylic polymerizable compounds other than those listed above include acrylic morpholine, glycerol acrylate, polyether acrylate, N-vinyl formamide, N-vinyl caprolactam, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, polyethylene glycol acrylate, EO-modified trimethylolpropane triacrylate, EO-modified bisphenol A diacrylate, aliphatic urethane oligomer, and polyester oligomer.

[0094] Furthermore, examples of the curing initiator for the curable resin include a heat curing initiator and a photocuring initiator. The curing initiator may be one that is cured by some energy ray other than heat or light (e.g., an electron beam). When the curing initiator is a heat curing initiator, the curable resin is a heat curable resin, and when the curing initiator is a photocuring initiator, the curable resin is a photocurable resin.

[0095] Among these, it is preferable to use an ultraviolet curing initiator as the curing initiator. The ultraviolet curing initiator is a type of photocuring initiator. Examples of the ultraviolet curing initiator include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one. Therefore, it is preferable that the curable resin is an ultraviolet curable resin. In addition, from the viewpoint of transparency, it is more preferable that the curable resin is an ultraviolet curable acrylic resin.

[0096] The method for forming the grid structure 20 is not particularly limited as long as it is a method capable of forming the above-mentioned base portion 21 and the convex streak portion 22. For example, a method for forming projections and recesses by photolithography, imprinting, or the like can be used. Among these, from the viewpoints of forming a projection and recess pattern easily in a short time and further capable of reliably forming the base portion 21, it is preferable to form the base portion 21 and the convex streak portion 22 of the grid structure 20 by imprinting.

[0097] When forming the base portion 21 and the convex streak portions 22 of the grid structure 20 by nanoimprinting, for example, after a material for forming the grid structure 20 (grid structure material) is applied onto the substrate 10, a master having projections and recesses is pressed against the grid structure material, and in this state, ultraviolet light is irradiated or heat is applied to harden the grid structure material. In this way, the grid structure 20 having the base portion 21 and the convex streak portions 22 can be formed.

[0098] <2.3. Reflective film (functional film)> A polarizing element 1 according to this embodiment includes a reflective film 30 formed on the protruding stripes 22 of a grid structure 20, as shown in FIGS.

[0099] 1, the reflective film 30 is formed so as to cover the tips 22a and parts of the side surfaces 22b of the convex stripes 22 of the grid structure 20. As shown in Fig. 1, the reflective film 30 is formed so as to extend along the longitudinal direction (Y direction) of the convex stripes 22 of the grid structure 20. This allows the reflective film 30 to reflect light that has entered the polarizing element 1 and has an electric field component in a direction parallel to the longitudinal direction of the convex stripes 22 (reflection axis direction: Y direction).

[0100] The material constituting the reflective film 30 is not particularly limited as long as it is a material that has reflectivity for light in the used band, for example, a metal material such as a simple metal element such as Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, or Te, or an alloy containing one or more of these elements.

[0101] The reflective film 30 may be a single layer film made of the above metal, or may be a multi-layer film made of multiple metal films. The reflective film 30 may include other layers such as a dielectric film as needed, as long as it has a reflective function. The dielectric film is a thin film made of a dielectric. The dielectric film may be made of a common material such as SiO2, Al2O3, MgF2, or TiO2. The refractive index of the dielectric film is preferably greater than 1.0 and less than or equal to 2.5. The optical characteristics of the reflective film 30 are also affected by the refractive index of the surroundings, so the polarization characteristics may be controlled by the material of the dielectric film.

[0102] <2.4. Special shapes of convex stripes and reflective film> Here, the special shapes of the convex stripes 22 of the grid structure 20 and the reflective film 30 in the polarizing element 1 according to this embodiment will be described in detail.

[0103] 1 and 5, in the polarizing element 1 according to this embodiment, the reflective film 30 is formed so as to cover the tip 22a and the upper side of at least one of the side surfaces 22b of the convex streak portion 22 of the grid structure 20, but not to cover the lower sides of both side surfaces 22b of the convex streak portion 22 and the base portion 21. Note that, in the example of Fig. 1 and Fig. 5, the reflective film 30 covers the upper sides of both side surfaces 22b of the convex streak portion 22, but it may cover the upper side of only one of the side surfaces 22b of the convex streak portion 22.

[0104] Here, "a state in which the reflective film 30 covers the tip 22a of the convex streak portion 22 of the grid structure 20 and the upper side of at least one of the side surfaces 22b" means, for example, as shown in Figures 1 and 5, a state in which both the "tip 22a of the convex streak portion 22" and the "upper side of the side surface 22b connecting the tip 22a of the convex streak portion 22 and the base portion 21" are continuously covered with the reflective film 30, while the "lower side of the side surface 22b" and the "base portion 21" are exposed without being covered with the reflective film 30. In this state, the reflective film 30 does not cover the entire side surface 22b of the convex streak portion 22 (all the side surfaces 22b from the tip 22a of the convex streak portion 22 to the base portion 21).

[0105] Furthermore, the surface of the reflective film 30 that covers the tip 22a and the upper side of at least one of the side surfaces 22b of the convex rib portion 22 (hereinafter sometimes referred to as the "top of the convex rib portion 22") has a rounded, curved shape (for example, a vertically elongated, approximately elliptical shape) and bulges in the width direction (X direction) of the convex rib portion 22. In this way, the surface of the reflective film 30 has a rounded, smoothly curved curved shape and does not have sharp corners or steps. The maximum width W of the reflective film 30 that covers the top of the convex rib portion 22 in this way is MAX is the width W of the bottom of the protruding portion 22 B That's all. Furthermore, W MAX is W B It is preferable that it is greater than .

[0106] Here, the maximum width W of the reflective film 30 that covers the protruding portion 22 MAX is the maximum horizontal width among the horizontal widths of the outermost surfaces on both sides of the reflective film 30 in the width direction (X direction) of the convex stripe 22. As shown in Figs. 1 and 5, the horizontal width (width in the X direction) of the outermost surfaces on both sides of the reflective film 30 that covers the convex stripe 22 varies depending on the height position (height in the Z direction) of the reflective film 30, but the maximum value of these horizontal widths is the maximum width W MAX In other words, the maximum width W MAX is the maximum value of the total width of the thickness Ds×2 of the reflective film 30 on both sides and the horizontal width W of the protruding stripe 22. For example, when light is incident on the grid structure 20 from the front direction (Z direction) (when the incident angle θ=0°), W MAX corresponds to the effective grid width of the reflective film 30.

[0107] Width W of the bottom of the ridge portion 22 B 1 and 3, is the horizontal width (width in the X direction) of the convex rib portion 22 at a height position (height in the Z direction) 20% above the height H of the convex rib portion 22 from the lowest part of the convex rib portion 22 (the upper surface of the base portion 21). In other words, the width W of the bottom of the convex rib portion 22 B is the horizontal width of the convex ridge portion 22 at a height of 0.2×H above the top surface of the base portion 21.

[0108] In addition, the width W of the top of the protruding portion 22 T1 and 3, is the horizontal width (width in the X direction) of the ridge portion 22 at a height position (height in the Z direction) 20% below the height H of the ridge portion 22 from the tip 22a of the ridge portion 22. In other words, the width W of the top of the ridge portion 22 T is the horizontal width of the ridge portion 22 at a position 0.8×H above the top surface of the base portion 21 (i.e., at a position 0.2×H below the tip 22a of the ridge portion 22).

[0109] In the following description, the convex structure formed by combining the convex stripes 22 and the reflective film 30 is referred to as a "grid," and the height of the convex structure formed by combining the convex stripes 22 and the reflective film 30 (i.e., the grid) is sometimes referred to as a "grid height." MAX "Grid maximum width W MAX " and the width W of the bottom of the protruding portion 22 B "Grid bottom width W B The width W of the top of the protruding portion 22 is also called the width W of the top of the protruding portion 22. T "The width of the top of the convex stripe W T The width at the center position of the height direction of the ridge portion 22 is sometimes referred to as the "ridge portion center width."

[0110] In this manner, in this embodiment, the width W B The horizontal width of the convex ridge portion 22 at a height position 20% above the lowest part (bottom) of the convex ridge portion 22 is used as the width W of the top of the convex ridge portion 22. T The horizontal width of the convex streak portion 22 at a height position 20% below the tip 22a of the convex streak portion 22 is used as the width. The reason for this is that the width of the bottom of the convex streak portion 22 on the upper surface of the base portion 21 and the width of the tip 22a of the convex streak portion 22 vary greatly depending on the manufacturing conditions of the grid structure 20, and it is difficult to measure these widths precisely.

[0111] As described above, the grid structure 20 according to this embodiment is formed with the tapered convex rib portion 22 and the reflective film 30 that covers only the tip 22a and the upper side of the side surface 22b of the convex rib portion 22. The lower side of the side surface 22b of the convex rib portion 22 is not covered with the reflective film 30 and is open.

[0112] As a result, the cross-sectional shape of the protruding portion 22 covered with the curved reflective film 30 (i.e., the cross-sectional shape of the grid) has the following special cross-sectional shape. That is, as shown in Figs. 1 and 5, the horizontal width of the upper part of the protruding portion 22 where the reflective film 30 is present (for example, the maximum grid width W MAX ) is large, and the horizontal width of the part of the exposed protrusion 22 that is not covered with the reflective film 30 from the center to the bottom side (for example, the width W B ) is smaller. The cross-sectional shape of the entire convex structure (i.e., "grid") composed of the convex stripe portion 22 and the reflective film 30 is constricted inwardly at a position directly below the lower end of the curved reflective film 30, and has a constricted portion with a narrower width in the X direction. Such a special cross-sectional shape of the grid can be likened to the shape of a tree. Specifically, the round and large leaf portion of the tree corresponds to the portion of the reflective film 30 that covers the top of the convex stripe portion 22, the trunk portion of the tree corresponds to the lower side portion of the convex stripe portion 22 that is not covered by the reflective film 30, and the ground on which the tree grows corresponds to the base portion 21. Therefore, in the following description, the special cross-sectional shape of the grid composed of the convex stripe portion 22 and the reflective film 30 of the grid structure 20 as described above is referred to as a "special tree shape."

[0113] The grid of the grid structure 20 of the polarizing element 1 according to this embodiment has a special tree shape as described above. As a result, for example, as shown in FIG. 31 described later, when incident light is incident on the polarizing element 1 from an oblique direction, the effective grid width W A becomes smaller, and the gap width W G becomes large. Here, the effective grid width W A is the width of the reflective film 30 in the direction perpendicular to the obliquely incident light. G is the gap between the reflective films 30 of two adjacent grids, and is the width of the gap in the direction perpendicular to the obliquely incident light. AAs the gap width W is larger, the obliquely incident light is more likely to be reflected by the reflective film 30 and is less likely to reach the transparent protrusions 22 and the base portion 21. Therefore, the transmittance of the obliquely incident light in the polarizing element 1 decreases. G The larger this is, the more easily the obliquely incident light can pass between the two adjacent reflective films 30, 30 and reach the transparent protruding stripe portion 22 and the base portion 21. Therefore, the transmittance for obliquely incident light can be increased.

[0114] Therefore, since the grid of the polarizing element 1 according to this embodiment has the above-mentioned special tree shape, the gap width W G becomes larger, and the obliquely incident light passes through the gaps between the round reflective films 30, 30, reaches the transparent grid structure 20, and is easily transmitted. Therefore, the transmission axis transmittance Tp of the obliquely incident light is high, and the transmittance and polarization separation characteristics (Tp×Rs characteristics) for the obliquely incident light are very excellent. Furthermore, a good balance can be achieved between the reflection function of the reflective film 30 for the obliquely incident light and the transmission function of the grid structure 20 for the obliquely incident light, and the polarization separation characteristics for the obliquely incident light can be further improved.

[0115] <2.5. Methods for forming reflective films and examples> Now, with reference to FIG. 5, a method for forming the reflective film 30 will be described.

[0116] As a method for forming the reflective film 30 so that it covers the tip 22a and part of both side surfaces 22b of the protruding stripe portion 22 of the grid structure 20, it is preferable to form the reflective film 30 by alternately performing sputtering or vapor deposition from an oblique direction (film deposition incidence angle φ) on the protruding stripe portion 22 of the grid structure 20 as shown in Fig. 5. In this way, the reflective film 30 can be formed so as to cover the tip 22a and the upper side of both side surfaces 22b of the protruding stripe portion 22. The film deposition incidence angle φ for forming the reflective film 30 by sputtering or vapor deposition is not particularly limited, but can be, for example, about 5 to 70° with respect to the surface of the substrate 10.

[0117] In this manner, in this embodiment, after forming the grid structure 20 made of a transparent material, the reflective film 30 made of a metal material is formed by sputtering or vapor deposition. This allows the film formation conditions, materials, and film thickness of the reflective film 30 to be easily changed. In addition, it is also easy to deal with the case where the reflective film 30 is made of a multilayer film. For this reason, a film design utilizing an interference effect is possible by combining metals, semiconductors, and dielectrics, and when forming the reflective film 30 by etching as in the conventional technology, it is not necessary to consider the material composition that can be etched. This makes it easy to adjust the reflectance of polarized waves parallel to the grid structure 20 and to adjust the transmittance (transmittance amount) of polarized waves perpendicular to the grid. In addition, since the reflective film 30 is formed after forming the grid structure 20, there is no need for equipment such as a vacuum dry etching device, and there is no need to prepare safety devices such as gases and detoxification devices that are suited to complicated processes and etching materials. Therefore, it is possible to reduce running costs such as capital investment and maintenance, and cost benefits can be obtained.

[0118] The thickness Dt of the reflective film 30 covering the tip 22a of the protruding portion 22 shown in FIG. 5 and the thickness Ds of the reflective film 30 covering the side surface 22b of the protruding portion 22 are not particularly limited and can be appropriately changed according to the shape of the protruding portion 22 of the grid structure 20 and the performance required for the reflective film 30. For example, from the viewpoint of obtaining a better reflection performance, the thicknesses Dt and Ds of the reflective film 30 are preferably 2 to 200 nm, more preferably 5 to 150 nm, further preferably 10 to 100 nm, and particularly preferably 15 to 80 nm. The thickness Ds of the reflective film 30 is the thickness of the thickest part of the reflective film 30 covering the side surface 22b of the protruding portion 22 as shown in FIG. 5.

[0119] Furthermore, the shape of the reflective film 30 is not particularly limited as long as it is a shape that can form the special tree shape described above, and can be selected appropriately depending on the conditions of the equipment used to form the reflective film 30 and the performance required of the reflective film 30.

[0120] Fig. 6 is a cross-sectional view showing a typical example of the shape of the reflective film 30. As shown in Fig. 6, the reflective film 30 may have various shapes as long as it is curved so as to wrap around the top of the protruding stripe 22 (the tip 22a and the upper side of the side surface 22b).

[0121] For example, the reflective film 30A shown in Fig. 6 wraps around the tops of the convex stripes 22A, 22B, and 22C of various cross-sectional shapes, and has a generally elliptical shape that bulges out greatly in the width direction of the convex stripe 22. The reflective film 30B has a curved shape that wraps around the top of the generally wedge-shaped convex stripe 22D. The reflective film 30C has a curved shape that wraps around the top of the trapezoidal convex stripe 22A. The coverage Rc of one side surface 22b of the convex stripe 22 by these reflective films 30B and 30C and the coverage Rc of the other side surface 22b are generally the same.

[0122] The reflective film 30D also wraps around and covers the top of the wedge-shaped protruding portion 22D, but is unevenly distributed on one side surface 22b (the left side surface 22b shown in FIG. 6) of the protruding portion 22. Specifically, the reflective film 30D covers a wide range of the left side surface 22b of the protruding portion 22, and the coverage rate Rc is about 80%. On the other hand, the reflective film 30D only covers a narrow range on the upper side of the right side surface 22b, and the coverage rate Rc is about 25%. In this way, the coverage rate Rc of the reflective film 30D may differ between one side surface 22b and the other side surface 22b of the protruding portion 22.

[0123] <2.6. Suitable range of coverage rate Rc of ridges by reflective coating> Next, a suitable range of the coverage Rc of the side surface 22b of the protruding stripe 22 by the reflective film 30 according to this embodiment will be described.

[0124] The coverage rate Rc is preferably 25% or more and 80% or less. Here, the coverage rate Rc is the ratio of the height (Hx) of the portion of the side surface 22b of the protruding portion 22 covered by the reflective film 30 to the height (H) of the protruding portion 22 shown in Figures 1 and 5. The coverage rate Rc is expressed by the following formula (1).

[0125] Rc [%] = (Hx / H) × 100 (1) H: Height of the protruding portion 22 in the Z direction Hx: the height in the Z direction of the portion of the side surface 22b of the protruding portion 22 that is covered with the reflective film 30

[0126] The open area ratio Rr is the ratio of the height (H-Hx) of the portion of the side surface 22b of the protruding portion 22 that is not covered by the reflective film 30 to the height (H) of the protruding portion 22 shown in Figures 1 and 5. The open area ratio Rr is expressed by the following formula (2).

[0127] Rr[%]=((H-Hx) / H)×100 ···(2)

[0128] According to the above definition, Rr = 100 - Rc. Therefore, when the coverage rate Rc of the side surface 22b of the convex streak portion 22 by the reflective film 30 is 25% or more and 80% or less, the opening rate Rr of the side surface 22b of the convex streak portion 22 by the reflective film 30 is 20% or more and 75% or less.

[0129] As described above, in the polarizing element 1 according to this embodiment, the coverage Rc of the side surface 22b of the convex streak portion 22 by the reflective film 30 is preferably 25% or more and 80% or less (i.e., the open area ratio Rr is 20% or more and 75% or less). In detail, in this embodiment, the reflective film 30 is formed so as to cover the tip 22a and the upper sides of both side surfaces 22b of the convex streak portion 22 and to leave the lower sides of both side surfaces 22b open without covering them. The coverage Rc is preferably 25% or more and 80% or less, more preferably 30% or more and 70% or less, and even more preferably 40% or more and 50% or less.

[0130] With this configuration, the polarizing element 1 according to this embodiment can exhibit sufficient transmittance even for obliquely incident light with a large incident angle θ (for example, 45 to 60°). For example, when the polarizing element 1 separates obliquely incident light into S-polarized light (reflected light) and P-polarized light (transmitted light), the transmittance Tp of the P-polarized light (transmitted light) that passes through the polarizing element 1 can be maintained at a high value regardless of the incident angle θ of the obliquely incident light. In addition, by setting the coverage Rc to 25% or more and 80% or less, the contrast (CR=Tp / Ts), which is the ratio of the transmission axis transmittance (Tp) to the transmission axis reflectance (Ts), can be maintained at a good level, and the reflection action of the reflective film 30 described above can be more reliably exhibited without depending on the incident angle θ. Therefore, regardless of the incident angle θ of the obliquely incident light, high transmittance of the transmitted light can be ensured, and the polarization separation characteristics can be improved.

[0131] In contrast, in a comparative example, when the reflective film 30 is formed to cover only the tip 22a of the protruding portion 22 of the grid structure 20, or when the reflective film 30 is formed to cover the entire tip 22a and one side surface 22b of the protruding portion 22 (see FIG. 18, for example), the variation in transmittance Tp increases depending on the incidence angle θ of the obliquely incident light, and it is considered that sufficient transmittance cannot be obtained even for obliquely incident light with a large incidence angle θ. Also, in a comparative example, when the reflective film 30 covers the entire tip 22a and both side surfaces 22b of the protruding portion 22 of the grid structure 20 (when the coverage rate Rc is 100%), the transmittance decreases significantly as the incidence angle θ of the obliquely incident light increases.

[0132] Therefore, from the viewpoint of improving the transmittance of transmitted light and the polarization separation characteristics regardless of the incidence angle θ of obliquely incident light, it is preferable to cover the tip 22a of the convex streak portion 22 and at least a portion of one of the side surfaces 22b (the upper side of the side surface 22b) with a reflective film 30, as in the polarizing element 1 of this embodiment.

[0133] Furthermore, from the viewpoint of the Tp×Rs characteristics required for a polarizing beam splitter (PBS), in the polarizing element 1 of this embodiment, it is preferable that the coverage rate Rc of the side surface 22b of the convex stripe portion 22 by the reflective film 30 is 25% or more and 80% or less (see, for example, Figure 27).

[0134] When the coverage Rc is less than 25%, the transmission axis transmittance Tp of the P-polarized light passing through the polarizing element 1 decreases, the transmittance Tp varies depending on the incident angle θ, and a sufficiently high Tp×Rs value cannot be obtained. Therefore, it is not possible to obtain sufficient transmittance of the transmitted light and the polarization separation characteristic expressed by Tp×Rs for obliquely incident light with a large incident angle θ. On the other hand, when the coverage Rc is more than 80% (see, for example, FIG. 20), the transmission axis transmittance Tp decreases as the incident angle θ of the obliquely incident light increases (for example, 45 to 60°), as in the case where the tip 22a and both side surfaces 22b of the convex stripe portion 22 of the grid structure 20 are entirely covered, and the transmittance Tp varies depending on the incident angle θ.

[0135] Therefore, the coverage Rc of the side surface 22b of the protruding stripe portion 22 by the reflective film 30 is preferably 25% or more and 80% or less (see, for example, FIG. 27). As a result, when light is incident on the polarizing element 1 from an oblique direction at an incident angle θ of, for example, 45°, the transmission axis transmittance Tp of the second polarized light (P polarized light) transmitted through the polarizing element 1 can be made 75% or more. As a result, Tp×Rs can be made 70% or more. Therefore, even when a wide range of obliquely incident light is incident at a large incident angle θ, the transmittance of the second polarized light (P polarized light) in the transmission axis direction of the polarizing element 1 can be increased, improving the polarization separation characteristics of the polarizing element 1, and the polarizing element 1 can suitably separate the obliquely incident light into the first polarized light (S polarized light) and the second polarized light (P polarized light).

[0136] From the same viewpoint, it is more preferable that the coverage Rc is 30% or more and 70% or less (i.e., the open ratio Rr is 30% or more and 70% or less). As a result, under the above-mentioned oblique incidence conditions, a high transmittance Tp of 80% or more can be obtained, and a high Tp×Rs of 72% or more can be obtained. Also, it is more preferable that the coverage Rc is 30% or more and 60% or less (i.e., the open ratio Rr is 40% or more and 70% or less). As a result, under the above-mentioned oblique incidence conditions, a high transmittance Tp of 83% or more can be obtained, and a high Tp×Rs of 75% or more can be obtained. Furthermore, it is even more preferable that the coverage Rc is 40% or more and 50% or less (i.e., the open ratio Rr is 50% or more and 60% or less). As a result, under the above-mentioned oblique incidence conditions, an extremely high transmittance Tp of 85% or more can be obtained, and a very high Tp×Rs of 77% or more can be obtained.

[0137] With regard to the reflection axis reflectance Rs, it is preferable that the coverage Rc is 20% or more, which makes it possible to obtain a high reflectance Rs of 85% or more under the above-mentioned oblique incidence conditions.

[0138] Regarding the contrast CR of the transmitted light (CR=Tp / Ts), if the coverage Rc is 20% or more, a sufficient contrast CR can be obtained. The higher the coverage Rc, the higher the contrast CR.

[0139] <2.7. Preferred range of Tp × Rs> Next, a suitable range for "Tp×Rs," which is an index representing the polarization separation characteristics of the wire-grid polarizer 1 according to this embodiment, will be described.

[0140] Tp×Rs [%] is the product of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) expressed as a percentage. This Tp×Rs is an index representing the polarization separation characteristics of the wire-grid polarizer 1. Tp×Rs[%]=(Tp[%] / 100)×(Rs[%] / 100)×100

[0141] As described above, the transmission axis transmittance (Tp) is the transmittance of the second polarized light (P polarized light) having an electric field component parallel to the transmission axis (X direction) of the polarizing element 1. The reflection axis reflectance (Rs) is the reflectance of the first polarized light (S polarized light) having an electric field component parallel to the reflection axis (Y direction) of the polarizing element 1.

[0142] When the wire grid polarizer 1 according to this embodiment is used as a polarizing beam splitter to split incident light into S-polarized light and P-polarized light (see Figs. 15 to 17), the polarizer 1 is disposed at a predetermined angle (e.g., 45°) with respect to the incident light from the light source. For example, when the incident light from the light source is incident on the polarizer 1 at an incident angle θ of about 45°, the incident light is split by the polarizer 1 into a first polarized light (S-polarized light: reflected light) and a second polarized light (P-polarized light: transmitted light). The S-polarized light is light of the incident light having an electric field component parallel to the longitudinal direction of the convex stripe portion 22 of the grid structure 20 (the reflection axis direction: Y direction shown in Fig. 2). On the other hand, the P-polarized light is light of the incident light having an electric field component parallel to the width direction of the convex stripe portion 22 of the grid structure 20 (the transmission axis direction: X direction shown in Fig. 2).

[0143] The S-polarized light in the reflection axis direction mainly becomes reflected light reflected by the reflective film 30 of the polarizing element 1. The reflectance [%] of the S-polarized light at this time is the reflection axis reflectance (Rs). The reflection axis reflectance (Rs) represents the proportion of S-polarized light reflected by the polarizing element 1 out of the S-polarized light incident on the polarizing element 1. The reflection axis transmittance (Rp) represents the proportion of S-polarized light transmitted through the polarizing element 1 out of the S-polarized light incident on the polarizing element 1.

[0144] On the other hand, P polarized light in the transmission axis direction mainly becomes transmitted light that passes through the transparent grid structure 20 and substrate 10 of the polarizing element 1. The transmittance [%] of the P polarized light at this time is the transmission axis transmittance (Tp). The transmission axis transmittance (Tp) represents the proportion of P polarized light that is transmitted through the polarizing element 1 out of the P polarized light incident on the polarizing element 1. The transmission axis reflectance (Ts) represents the proportion of P polarized light that is reflected by the polarizing element 1 out of the P polarized light incident on the polarizing element 1.

[0145] Therefore, a higher transmission axis transmittance Tp means that the P polarized light in the transmission axis direction can be transmitted more efficiently. Also, a higher reflection axis reflectance Rs means that the S polarized light in the reflection axis direction can be reflected more efficiently. Therefore, the higher the Tp×Rs value, which is the product of Tp and Rs, the higher the transmittance of P polarized light (transmitted light) and the reflectance of S polarized light (reflected light), and the better the polarization separation characteristics as a polarizing beam splitter.

[0146] Here, a suitable range of the value of Tp×Rs according to this embodiment will be described. Consider a case where light of a predetermined range of wavelengths (e.g., 430 to 680 nm) is incident on the polarizing element 1 according to this embodiment from an oblique direction at a predetermined incidence angle θ (e.g., 45°) and separated into P polarized light (transmitted light) and S polarized light (reflected light). In the case of such oblique incidence conditions, from the viewpoint of good polarization separation characteristics of the polarizing element 1, it is preferable that Tp×Rs is 70% or more.

[0147] If Tp×Rs is less than 70%, the efficiency of light utilization is poor in a display device to which the polarizing element is applied, the brightness of the displayed image is insufficient, and visibility is poor. In contrast, if Tp×Rs is 70% or more, the efficiency of light utilization can be improved in a display device to which the polarizing element 1 is applied, sufficient brightness of the displayed image can be ensured, and visibility can be improved.

[0148] Furthermore, Tp×Rs is more preferably 72% or more, even more preferably 75% or more, and particularly preferably 80% or more, which can further improve the light utilization efficiency as well as the brightness and visibility of the displayed image.

[0149] <2.8. Suitable range of height H of convex rib> When light is incident on the polarizing element 1 according to this embodiment at a relatively large incident angle θ (for example, 45°), the height H of the convex stripe portion 22 of the grid structure 20 (see Figs. 1, 3, etc.) is preferably 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more (see Fig. 24). This provides a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of the transmitted light.

[0150] Specifically, regarding the transmittance, if the height H of the convex ridge portion 22 is 160 nm or more, the transmission axis transmittance Tp of obliquely incident light is 80% or more, and high transmittance is obtained. Furthermore, if H is 180 nm or more, Tp of 85% or more is obtained, which is more preferable. In addition, if H is 220 nm or more, Tp of 87% or more is obtained, which is particularly preferable.

[0151] Regarding the Tp×Rs characteristics required for a polarizing beam splitter (PBS), if the height H of the convex stripe 22 is 160 nm or more, an excellent Tp×Rs of 70% or more can be obtained. Furthermore, if H is 180 nm or more, a Tp×Rs of 75% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, a Tp×Rs of 77% or more can be obtained, which is particularly preferable.

[0152] As for the contrast CR of the transmitted light (CR=Tp / Ts), the height H of the convex ridge 22 needs only to be 100 nm or more, but if H is 160 nm or more, an excellent contrast CR of 150 or more can be obtained. Furthermore, if H is 180 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, an excellent CR of 500 or more can be obtained, which is particularly preferable.

[0153] As described above, in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1, especially Tp, it is preferable that the height H of the convex streak portion 22 is larger. The reason for this is considered to be as follows. That is, when the deposition incidence angle φ (see FIG. 5) when the reflective film 30 is deposited on the convex streak portion 22 by sputtering or vapor deposition is the same, the lower the height H of the convex streak portion 22, the higher the coverage Rc of the reflective film 30. When the coverage Rc is larger, the range of the convex streak portion 22 covered by the reflective film 30 becomes wider, so that P polarized light is less likely to pass through the grid structure 20, and the transmittance Tp decreases. Therefore, under the condition that the deposition incidence angle φ is the same, it is preferable to increase the height H of the convex streak portion 22 to reduce the coverage Rc and increase the transmittance Tp.

[0154] <2.9. Suitable range of tip thickness Dt of functional film (reflective film)> When incident light is incident on the polarizing element 1 of this embodiment at a relatively large incident angle θ (e.g., 45°), the thickness Dt of the reflective film 30 covering the tip 22a of the convex portion 22 of the grid structure 20 (tip thickness Dt of the reflective film 30: see Figure 5) is preferably 5 nm or more, and more preferably 15 nm or more (see, for example, Figure 25).

[0155] If the tip thickness Dt of the reflective film 30 is 5 nm or more, both the reflection axis reflectance Rs and the transmission axis transmittance Tp of the obliquely incident light become 85% or more, and high transmittance is obtained. Furthermore, when the Tp characteristic and the Tp×Rs characteristic required for a polarizing beam splitter are taken into consideration, it is more preferable that Dt is 15 nm or more.

[0156] <2.10. Suitable range of side thickness Ds of functional film (reflective film)> Furthermore, the thickness Ds of the reflective film 30 covering the side surface 22b of the ridge portion 22 of the grid structure 20 (side surface thickness Ds of the reflective film 30: see FIG. 5) is preferably 10 nm or more and 30 nm or less, more preferably 12.5 nm or more and 25 nm or less, and particularly preferably 15 nm or more and 25 nm or less (see FIG. 26, for example). This provides a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of the transmitted light.

[0157] Specifically, when the side thickness Ds of the reflective film 30 is 10 nm or more and 30 nm or less, the transmission axis transmittance Tp of obliquely incident light becomes 80% or more, and high transmittance is obtained. Furthermore, when Ds is 12.5 nm or more and 25 nm or less, Tp of 85% or more is obtained, which is more preferable.

[0158] Regarding reflectance, if the side thickness Ds of the reflective film 30 is 10 nm or more, the reflection axis reflectance Rs of obliquely incident light becomes 80% or more, and a high reflectance is obtained. Furthermore, if Ds is 12.5 nm or more, Rs of 85% or more can be obtained, which is more preferable.

[0159] Regarding the Tp×Rs characteristic required for a polarizing beam splitter (PBS), if the side thickness Ds of the reflective film 30 is 12.5 nm or more and 30 nm or less, an excellent Tp×Rs of 70% or more can be obtained. Furthermore, if Ds is 15 nm or more and 25 nm or less, a Tp×Rs of 76% or more can be obtained, which is more preferable.

[0160] As for the contrast CR of the transmitted light (CR=Tp / Ts), the side thickness Ds of the reflective film 30 needs to be 10 nm or more, but if Ds is 12.5 nm or more, an excellent contrast CR of 50 or more can be obtained. Furthermore, if Ds is 15 nm or more, a CR of 100 or more can be obtained, which is more preferable.

[0161] <2.11. Uneven distribution of reflective film> Furthermore, in the polarizing element 1 according to this embodiment, the reflective film 30 covering the convex streak portion 22 may be unevenly distributed on one side of the convex streak portion 22 to have an asymmetric shape in the width direction (X direction) of the convex streak portion 22 (see, for example, FIG. 29). Specifically, the side thickness Ds or the coverage Rc of the reflective film 30 may be changed between one side surface 22b and the other side surface 22b of the convex streak portion 22 to cause the reflective film 30 to be unevenly distributed on one side surface 22b of the convex streak portion 22. In other words, the reflective film 30 may be configured to cover one side surface 22b of the convex streak portion 22 thickly and widely and to cover the other side surface 22b thinly and narrowly.

[0162] When the reflective film 30 is unevenly distributed on one side of the convex ridge portion 22 in this manner, it is preferable that the difference between the transmission axis transmittance Tp(+) of incident light having an incident angle of +θ (+30° to +60°) with respect to the polarizing element 1 and the transmission axis transmittance Tp(-) of incident light having an incident angle of -θ (-30° to -60°) be within 3%. It is preferable that the thickness Ds and coverage Rc of the reflective film 30 covering one side surface 22b and the other side surface 22b of the convex ridge portion 22 are adjusted so that the difference between Tp(+) and Tp(-) is within 3%, thereby appropriately unevenly distributing the reflective film 30 on one side of the convex ridge portion 22.

[0163] An incident angle of +θ means that obliquely incident light is incident on the convex ridge portion 22 from a direction tilted toward one side in the X direction (the width direction of the convex ridge portion 22). On the other hand, an incident angle of -θ means that obliquely incident light is incident on the convex ridge portion 22 from a direction tilted toward the other side in the X direction (see FIG. 29, for example).

[0164] As described above, when the reflective film 30 is unevenly distributed on one side of the convex ridge portion 22, it is preferable to set the difference between Tp(+) and Tp(-) to within 3%. This makes it possible to obtain a high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and a high contrast CR of transmitted light, even when the reflective film 30 is unevenly distributed on one side of the convex ridge portion 22.

[0165] Specifically, with regard to transmittance, even when the reflective film 30 is unevenly distributed on one side, the transmission axis transmittance Tp of obliquely incident light with an incident angle θ of +45° and -45° is 85% or more, thereby achieving high transmittance.

[0166] Regarding reflectance, even when the reflective film 30 is unevenly distributed on one side, the reflection axis reflectance Rs of obliquely incident light with an incident angle θ of +45° and −45° is 85% or more, and high reflectance is obtained.

[0167] Furthermore, with regard to the Tp×Rs characteristics required for a polarizing beam splitter (PBS), even when the reflective film 30 is biased to one side, the Tp×Rs of obliquely incident light with an incident angle θ of 45° is 75% or more, thereby obtaining excellent Tp×Rs characteristics.

[0168] Furthermore, regarding the contrast CR of the transmitted light (CR=Tp / Ts), an excellent contrast CR can be obtained even when the reflective film 30 is unevenly distributed on one side. Furthermore, from the viewpoint of improving the contrast, of the thicknesses Ds of the reflective films 30 covering the one side surface 22b and the other side surface 22b of the protruding stripe portion 22, the thinner thickness Ds is preferably 5 nm or more (its coverage rate Rc is 22% or more), and more preferably the thinner thickness Ds of the reflective film 30 is 10 nm or more (its coverage rate Rc is 33% or more).

[0169] <2.12. Other components> The polarizing element 1 according to this embodiment may further include components other than the substrate 10, the grid structure 20, and the reflective film 30 described above.

[0170] For example, as shown in Fig. 7, the polarizing element 1 preferably further includes a protective film 40 formed so as to cover at least the surface of the reflective film 30. In particular, as shown in Fig. 7, it is more preferable that the protective film 40 covers the entire surface of the grid structure 20. That is, it is more preferable that the protective film 40 is formed so as to cover all of the side surfaces 22b of the protruding stripe portions 22 of the grid structure 20, the surfaces of the base portion 21, and the surface of the reflective film 30. By forming such a protective film 40, it is possible to further improve the scratch resistance, antifouling properties, and waterproof properties of the polarizing element 1.

[0171] More preferably, the protective film 40 further includes a water-repellent coating or an oil-repellent coating, which can further improve the stain-proofing and waterproofing properties of the polarizing element 1.

[0172] The material constituting the protective film 40 is not particularly limited as long as it can enhance the scratch resistance, antifouling property, and waterproof property of the polarizing element 1. Examples of the material constituting the protective film 40 include a film made of a dielectric material, and more specifically, inorganic oxides, silane-based water-repellent materials, etc. Examples of inorganic oxides include Si oxides, Hf oxides, etc. The silane-based water-repellent material may contain a fluorine-based silane compound such as perfluorodecyltriethoxysilane (FDTS), or may contain a non-fluorine-based silane compound such as octadecyltrichlorosilane (OTS).

[0173] Among these materials, it is more preferable that the protective film 40 contains at least one of an inorganic oxide and a fluorine-based water-repellent material. When the protective film 40 contains an inorganic oxide, the scratch resistance of the polarizing element can be further improved, and when the protective film 40 contains a fluorine-based water-repellent material, the stain resistance and waterproofing of the polarizing element can be further improved.

[0174] The protective film 40 may be formed so as to cover at least the surface of the reflective film 30, but is more preferably formed so as to cover the entire surfaces of the grid structure 20 and the reflective film 30 as shown in FIG. 7. In this case, for example, as shown in the upper diagram of FIG. 7, the protective film 40 may cover the end face of the grid structure 20 (the end face of the base portion 21), or as shown in the lower diagram of FIG. 7, the protective film 40 may not cover the end face of the grid structure 20 (the end face of the base portion 21). Also, as shown in FIG. 8, the protective film 40 may be formed so as to cover the entire polarizing element 1, including the surface of the substrate 10 in addition to the surfaces of the grid structure 20 and the reflective film 30. In this way, by covering the outermost surface of the grid structure 20 or the polarizing element 1 with the protective film 40 made of an inorganic oxide, the thermal resistance R of the entire polarizing element 1 can be further reduced, and the heat dissipation of the polarizing element 1 can be further improved.

[0175] Furthermore, in the polarizing element 1 according to this embodiment, as shown in Fig. 9, it is preferable that a heat dissipation member 50 is provided so as to surround the periphery of the substrate 10. The heat dissipation member 50 can dissipate heat transferred from the substrate 10 more efficiently. Here, the heat dissipation member 50 is not particularly limited as long as it is a member with a high heat dissipation effect. The heat dissipation member 50 may be, for example, a heat sink, a heat spreader, a die pad, a heat pipe, a metal cover, a housing, or the like.

[0176] <2.13. Actual grid structure image> Next, with reference to Fig. 10, an example of an actual fabricated polarizing element 1 according to this embodiment and an enlarged image taken with a scanning electron microscope (SEM) will be described. Fig. 10A is an SEM image of the grid structure 20 before being covered with the reflective film 30, viewed from an oblique direction. Fig. 10B is an SEM image showing a cross section of the convex streak portion 22 of the grid structure 20 before being covered with the reflective film 30. Fig. 10C is an SEM image showing a cross section of the convex streak portion 22 of the grid structure 20 covered with the reflective film 30.

[0177] As shown in Figures 10A and 10B, the grid structure 20 is formed with a base portion 21 provided along the surface of the substrate 10, and protruding ridge portions 22 protruding from the base portion 21. The plurality of protruding ridge portions 22 are arranged at a substantially equal pitch P. Each of the protruding ridge portions 22 has a tapered shape that narrows in width as it moves away from the base portion 21. The width W of the top of the protruding ridge portion 22 is T is the width W of the bottom of the protruding portion 22 B The pitch P is smaller than the width W of the bottom of the protruding portion 22. B The height H of the protruding portion 22 is greater than the pitch P. In the example of FIG. 10, P=140 nm, W T = 10 nm, W B 10C, a reflective film 30 is formed so as to cover the tip 22a and both side surfaces 22b of the protruding stripe 22. The outer surface of the reflective film 30 is curved and rounded, and bulges out in the width direction of the protruding stripe 22.

[0178] <3. Manufacturing method of polarizing element> Next, a method for manufacturing the wire-grid polarizer 1 according to this embodiment will be described with reference to Fig. 11. Fig. 11 is a process chart showing the method for manufacturing the wire-grid polarizer 1 according to this embodiment.

[0179] As described above, the polarizing element 1 according to this embodiment is a hybrid wire-grid polarizing element 1 made of an inorganic material (substrate 10) and an organic material (grid structure 20). A method for manufacturing the hybrid wire-grid polarizing element 1 will be described below.

[0180] As shown in FIG. 11, the method for manufacturing the wire grid polarizer 1 according to this embodiment includes a grid structure material formation step (S10), a nanoimprinting step (S12), a grid structure formation step (S14), and a reflective film formation step (S16).

[0181] Grid structure material forming process (S10) First, in S10, a grid structure material 23 made of a transparent organic material (for example, an ultraviolet curable resin or a thermosetting resin) is laminated by coating or the like on a substrate 10 made of a transparent inorganic material (for example, glass). The above-mentioned various materials can be used as the inorganic material of the substrate 10. The above-mentioned various materials can be used as the organic material of the grid structure 20. Furthermore, the film thickness of the grid structure material 23 may be appropriately adjusted according to the dimensions of the base portion 21 and the protruding stripe portion 22 of the grid structure 20 formed by nanoimprinting in S20.

[0182] Nanoimprint process (S12) and grid structure formation process (S14) Next, in S12, nanoimprinting is performed on the grid structure material 23 to form a grid structure 20 on the substrate 10 in S14. The grid structure 20 is a fine concave-convex structure in which a base portion 21 provided on the substrate 10 and a plurality of protruding stripes 22 protruding from the base portion 21 are integrally formed. The fine concave-convex structure is a structure having minute protrusions and recesses on the order of, for example, several nm to several tens of nm.

[0183] In the nanoimprinting step of S12, a master 60 on which an inverted shape of the fine concave-convex shape of the grid structure 20 is formed is used to transfer the fine concave-convex shape of the master 60 to the surface of the grid structure material 23 (S12). As a result, a concave-convex pattern consisting of the base portion 21, the ridge portion 22, and the recessed portion 24 is formed in the grid structure material 23. Furthermore, in the nanoimprinting step, in addition to the transfer of the concave-convex pattern, the grid structure material 23 is irradiated with energy rays to harden the grid structure material 23 to which the concave-convex pattern has been transferred, thereby forming the grid structure 20 (S14). For example, when the grid structure material 23 is made of an ultraviolet curing resin, the ultraviolet curing resin to which the concave-convex pattern has been transferred may be hardened by irradiating the grid structure material 23 with ultraviolet rays using an ultraviolet irradiation device 66. Alternatively, when the grid structure material 23 is made of a thermosetting resin, the grid structure material 23 may be heated using a heating device 68 such as a heater to harden the thermosetting resin to which the concave-convex pattern has been transferred.

[0184] In the above steps S12 and S14, the convex streak portion 22 of the grid structure 20 is formed to have a tapered shape in which the width becomes narrower as it moves away from the base portion 21. The convex streak portion 22 in the example of Fig. 11 is trapezoidal (tapered), but may have various other tapered shapes as shown in Fig. 3.

[0185] In this manner, in the present embodiment, the tapered convex streaks 22 are imprinted in the nanoimprint step S12, so that the master 60 can be easily peeled off from the grid structure material 23, and the mold-removal property is excellent. Also, the convex streaks 22 of the grid structure 20 can be accurately molded into a desired shape without losing its shape.

[0186] Reflective film formation process (S16) Next, in S16, a reflective film 30 is formed using a metal material such as Al or Ag to cover a part of the protruding stripes 22 of the grid structure 20. The reflective film 30 is an example of a functional film that imparts a predetermined function to the polarizing element 1. The reflective film 30 is a thin metal film (a grid of thin metal wires) for reflecting incident light that is incident on the grid structure 20 of the polarizing element 1.

[0187] In this reflective film forming step S16, the reflective film 30 is formed as follows. That is, the reflective film 30 is formed so that it covers the tip 22a and the upper side of at least one side surface 22b of the convex ridge portion 22, but does not cover the lower sides of both side surfaces 22b of the convex ridge portion 22 or the base portion 21. Furthermore, the reflective film 30 is formed so that the surface of the reflective film 30 that covers the convex ridge portion 22 is rounded and bulges in the width direction of the convex ridge portion 22. In addition, the maximum width W of the reflective film 30 that covers the convex ridge portion 22 is MAX (Maximum grid width W MAX ) is the width W of the bottom of the convex part mentioned above B (Grid bottom width W B The reflective film 30 is formed so that the reflectance is equal to or greater than 1.

[0188] As a method for forming such a reflective film 30, for example, sputtering or vapor deposition can be used, as shown in Fig. 5. A metal material is sputtered or vapor deposited alternately from oblique directions onto the protruding stripes 22 of the grid structure 20 to form the reflective film 30. This makes it possible to suitably form the reflective film 30 in a desired shape so as to roundly surround the tops of the protruding stripes 22.

[0189] By forming the reflective film 30 in this manner, the convex stripe portion 22 of the grid structure 20 and the reflective film 30 have the special tree-like shape described above. As a result, as described above, even when light is obliquely incident on the polarizing element 1 at a relatively large and wide range of incident angles θ (e.g., 30 to 60°), the transmission axis transmittance Tp of the P-polarized light contained in the obliquely incident light can be maintained at a high value, and the transmittance of the P-polarized light (transmitted light) can be ensured. Therefore, the value of Tp×Rs can be maintained at a high value (e.g., 70% or more), and the polarization separation characteristic of the polarizing element 1 for obliquely incident light can be improved.

[0190] The manufacturing method of the polarizing element 1 according to this embodiment may include, as necessary, a step of forming a protective film 40 that covers the surface of the polarizing element 1 (protective film forming step) after the reflective film forming step S16 shown in Fig. 11. The protective film 40 is preferably formed so as to cover the entire surfaces of the grid structure 20 and the reflective film 30. The protective film 40 may be made of any of the various materials described above.

[0191] The above describes the method for manufacturing the polarizing element 1 according to this embodiment. Through the above-mentioned steps, it is possible to manufacture the polarizing element 1 having excellent polarization properties and heat dissipation properties without increasing the manufacturing cost of the polarizing element 1 or complicating the manufacturing process.

[0192] Here, for comparison with the manufacturing method according to this embodiment, a conventional manufacturing method for a wire-grid polarizer will be briefly described with reference to FIG.

[0193] 12, in a conventional method for manufacturing a wire-grid polarizer, first, in order to create a convex grid shape, a metal film 80 is formed on a substrate 10 (S20). In S20, a reflective film made of a material that reflects light in the used band, for example, a metal film 80 made of aluminum, is formed by sputtering or vapor deposition on the substrate 10 made of an inorganic material such as glass.

[0194] Next, a resist mask 70 is patterned on the metal film 80 using photolithography (S22). After that, the metal film 80 is etched using a vacuum dry etching device or the like to form a convex shape made of the metal film 80 (S24). For example, if the etching selectivity between the resist mask 70 and the metal film 80 cannot be obtained at this time, an oxide film such as SiO2 is further formed on the metal film 80 by sputtering or the like, and the resist mask 70 is formed on the oxide film by photolithography. After that, the resist mask 70 is peeled off from the metal film 880 (S26), and then a protective film 40 made of a SiO2 film or the like is formed by CVD or the like, and a water-repellent / oil-repellent coating process is also performed as necessary (S28).

[0195] In the above steps S20 to S28 of the conventional manufacturing method, a process for producing a reflective wire-grid polarizer with a basic configuration has been shown, but if the metal film 80 is a multi-layer film, a more complicated process is required. Therefore, it is expected that the conventional wire-grid polarizer produced by the process shown in S20 to S28 of Fig. 12 will be expensive to produce and will take a long time to produce. Furthermore, when mass-producing polarizers, in order to form minute convex shapes smaller than the wavelength of light, it is necessary to prepare multiple high-precision and expensive etching devices and photolithography devices according to the production volume, and it is expected that the capital investment will also be high.

[0196] In contrast, the manufacturing method for the polarizing element 1 according to this embodiment (see FIG. 11) uses an imprinting technique such as nanoimprinting to form the grid structure 20, and therefore can significantly reduce manufacturing costs, manufacturing time, and equipment investments compared to the conventional manufacturing method described above (see FIG. 12).

[0197] In the manufacturing method of the polarizing element 1 according to the present embodiment, nanoimprinting is performed on the grid structure material 23 (S12 in FIG. 11), but the conditions for nanoimprinting are not particularly limited. For example, as shown in S12 in FIG. 11, a replica master (or a main master) is used as the master 60, and while performing nanoimprinting, UV irradiation or heating is performed on the grid structure material 23, and the grid structure material 23 is cured in a state in which the concave-convex pattern is imprinted. Thereafter, the master 60 is released from the cured grid structure material 23. As a result, the grid structure 20 on which the base portion 21 and the convex stripe portion 22 are formed can be molded by transfer.

[0198] The master 60 used in the nanoimprint step S12 (FIG. 11) in the manufacturing method for the polarizing element 1 according to this embodiment can be manufactured by, for example, photolithography technology, as shown in FIG 13. FIG 13 is a process chart showing the manufacturing method for the master 60 according to this embodiment.

[0199] 13, first, a master metal film 62 is formed on a master substrate 61 (S30), and then a resist mask 70 is formed on the master metal film 62 (S32). Next, the master metal film 62 is etched using the resist mask 70, and grooves 65 corresponding to the protruding stripes 22 of the grid structure 20 are formed in the etched master metal film 62 (S34).

[0200] Thereafter, the resist mask 70 is peeled off from the master metal film 62 to obtain the master 60 (S36). The master 60 has a fine uneven structure consisting of a plurality of convex portions 63 and concave grooves 65 formed on the master substrate 61. The fine uneven structure on the surface of the master 60 has an inverted shape of the fine uneven structure on the surface of the grid structure 20 of the polarizing element 1. The concave grooves 65 of the master 60 have an inverted shape of the convex streak portions 22 of the grid structure 20, and the convex portions 63 of the master 60 have an inverted shape of the concave portions 24 between the convex streak portions 22, 22 of the grid structure 20.

[0201] Furthermore, the manufacturing method according to this embodiment may include, as necessary, a step (S38) of forming a release film coat 64 on the surface of the fine uneven structure of the master 60. By providing the release film coat 64 on the surface of the master 60, the master 60 can be easily peeled off from the grid structure material 23 after nanoimprinting is performed on the grid structure material 23 in the nanoimprinting step (S12) shown in Fig. 11, and the releasability can be further improved.

[0202] <4. Projection display device> Next, with reference to FIG. 14, a projection display device to which the wire-grid polarizer 1 according to this embodiment is applied will be described.

[0203] The projection display device according to this embodiment includes the above-described wire-grid polarizer 1 according to this embodiment. By including the polarizer 1 in the projection display device according to this embodiment, excellent polarization characteristics, and the heat resistance and heat dissipation properties of the polarizer 1 can be achieved.

[0204] Here, a projection display device is a device that projects light toward an object and irradiates the projected light (projection light) onto a display surface (projection surface) of the object to display a virtual image such as an image or video. Types of projection display devices include, for example, a head-up display device (HUD) and a projector device.

[0205] <4.1. Head-up display device> First, a head-up display device 100 including a wire-grid polarizer 1 according to this embodiment will be described with reference to Fig. 14. Fig. 14 is a schematic diagram showing an example of a head-up display device 100 according to this embodiment.

[0206] As shown in Fig. 14, a head-up display device 100 according to this embodiment includes the wire grid polarizer 1 according to this embodiment described above. Providing the polarizer 1 in the head-up display device 100 can improve polarization characteristics, heat resistance, and heat dissipation. Head-up displays incorporating conventional polarizers have poor heat dissipation properties and are therefore considered to have insufficient heat resistance when considering long-term use and future needs for higher brightness and enlarged display.

[0207] 14, the head-up display device 100 includes a light source 2, a display element 3 that emits a display image, a reflector 4 that reflects the display image onto a display surface 5, and a cover portion 6 that is provided at an opening of a housing 7. In the head-up display device 100, the arrangement of the polarizing element 1 is not particularly limited. For example, as shown in FIG. 14, the polarizing element 1 can be arranged between the display element 3 and the reflector 4.

[0208] Here, the head-up display device 100 may be a head-up display device for a vehicle that is provided in a vehicle. The head-up display device for a vehicle displays an image on a semi-transmissive plate (corresponding to the "display surface 5") such as a windshield or a combiner of the vehicle. The head-up display device for a vehicle is, for example, an image display device that is disposed on the dashboard of the vehicle, projects image light onto the windshield (display surface 5), and displays driving information as a virtual image.

[0209] The head-up display device 100 is configured to emit a display image from below toward the windshield surface (display surface 5). For this reason, sunlight may enter in a direction opposite to the emission direction of the display image and enter the display element 3. In the head-up display device 100 according to this embodiment, a reflector 4 is provided for reflecting and enlarging the display image in order to meet the demand for compactness and to enlarge the display image. In such a case, in a conventional head-up display device, sunlight that enters the reflector from the outside is concentrated near the display element, and there is a risk that heat will cause deterioration or failure of the display element.

[0210] In contrast, in the head-up display device 100 according to this embodiment, a hybrid polarizing element 1 having excellent heat dissipation and heat resistance is provided as described above in order to prevent sunlight from entering the display element 3. This polarizing element 1 can stably exhibit its polarization function even at high temperatures, for example, around 200° C. Therefore, even in a high-temperature environment, such as the inside of a car in summer, the polarizing element 1 can block sunlight that has entered the reflector 4 from the outside and prevent it from reaching the display element 3, thereby suppressing deterioration and failure of the display element 3.

[0211] Note that the components of the head-up display device 100 shown in FIG. 14 are examples of basic components, and the components of the projection display device are not limited to the example in FIG. 14, and other components may be provided as appropriate depending on the required performance, etc.

[0212] Furthermore, by using the polarizing element 1 as a pre-polarizing plate disposed in front of the display element 3, the polarizing element 1 can transmit a display image emitted from the display element 3 while suppressing the incidence of sunlight on the display element 3. This can further improve the heat resistance and durability of the head-up display device 100.

[0213] In addition, the arrangement of the wire grid polarizing element in the projection display device is not limited to the example of the arrangement of the polarizing element 1 in the head-up display device 100 shown in Fig. 14, and can be appropriately selected and changed depending on the configuration of the projection display device, the required performance, etc. For example, although not shown, the polarizing element 1 can be arranged between the display element 3 and the light source 2. Also, although not shown, the polarizing element 1 can be incorporated into the reflector 4. Furthermore, the cover portion 6 provided in the head-up display device 100 shown in Fig. 14 can also be composed of the polarizing element 1.

[0214] Although not shown, a heat dissipation member 50 (see FIG. 9) may be provided around the polarizing element 1 installed in the head-up display device 100. The heat dissipation member 50 can further improve the heat dissipation properties of the polarizing element 1, and therefore the polarization characteristics and heat resistance of the polarizing element 1 can be further improved.

[0215] <4.2. Projection display device equipped with a polarizing beam splitter> Next, with reference to Fig. 15 to Fig. 17, a projection display device using the reflective wire-grid polarizer 1 according to this embodiment as a polarizing beam splitter 230 will be described. First, matters common to the three specific examples of projection display devices 200A, 200B, and 200C (hereinafter, sometimes collectively referred to as "projection display device 200") shown in Fig. 15 to Fig. 17 will be comprehensively described below. After that, each specific example shown in Fig. 15 to Fig. 17 will be described individually.

[0216] 15 to 17, the projection display device 200 includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250. A phase difference compensation plate (not shown) may be provided between the polarizing beam splitter 230 and the reflective liquid crystal display element 240.

[0217] Light source 210 may be a point light source having one light emitting unit, or may be a light source having multiple light emitting units such as LEDs. The light emitted from light source 210 may be parallel light or diffuse light. Therefore, the light from light source 210 may be incident on polarizing beam splitter 230 (reflective wire grid polarizer) at an incident angle θ within a predetermined range (for example, a range of 45°±15°) centered on 45°.

[0218] The PS converter 220 is a polarization conversion element for converting the light from the light source 210 into a specific polarization (for example, P polarization or S polarization). The PS converter 220 may convert the light from the light source 210 into either P polarization or S polarization.

[0219] Polarizing beam splitter 230 is composed of a reflective wire-grid polarizer. The reflective wire-grid polarizer is an example of the wire-grid polarizer 1 according to this embodiment. Polarizing beam splitter 230 is disposed so that light from light source 210 is incident at an incident angle θ within a predetermined range including 45°. This predetermined range of incident angle θ is, for example, the above-mentioned 45°±15°, that is, not less than 30° and not more than 60°.

[0220] 15 to 17, for example, the polarizing beam splitter 230 is disposed at an inclination of 45° with respect to the incident direction of the incident light so that the incident light from the light source 210 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°. Also, the polarizing beam splitter 230 is disposed at an inclination of 45° with respect to the reflective liquid crystal display element 240 so that the incident light from the reflective liquid crystal display element 240 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°.

[0221] The polarizing beam splitter 230 separates the incident light into a first polarized light (S polarized light) and a second polarized light (P polarized light). For example, the polarizing beam splitter 230 may separate the S polarized light and the P polarized light by reflecting the first polarized light (S polarized light) of the incident light and transmitting the second polarized light (P polarized light). Conversely, the polarizing beam splitter 230 may separate the S polarized light and the P polarized light by reflecting the second polarized light (P polarized light) of the incident light and transmitting the first polarized light (S polarized light).

[0222] When the polarizing beam splitter 230 is to reflect a desired polarized light, the polarizing beam splitter 230 is disposed so that light containing the polarized light to be reflected is incident on the surface of the polarizing beam splitter 230 (i.e., the uneven surface on the side of the polarizing element 1 on which the grid structure 20 is formed). For example, as shown in FIG. 15, when the polarizing beam splitter 230 is to reflect S polarized light incident from the PS converter 220, the surface of the polarizing beam splitter 230 can be directed toward the PS converter 220 side from which the S polarized light is output. On the other hand, as shown in FIG. 16, when the polarizing beam splitter 230 is to reflect S polarized light incident from the reflective liquid crystal display element 240, the surface of the polarizing beam splitter 230 can be directed toward the reflective liquid crystal display element 240 side from which the S polarized light is output.

[0223] The reflective liquid crystal display element 240 is a display element that reflects incident light and emits light that represents a display image. As shown in Fig. 15 and Fig. 17, the reflective liquid crystal display element 240 may be arranged so that the first polarized light (S polarized light) reflected by the polarizing beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240. Alternatively, as shown in Fig. 16, the reflective liquid crystal display element 240 may be arranged so that the second polarized light (P polarized light) transmitted through the polarizing beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240.

[0224] 15 and 17, the reflective liquid crystal display element 240 reflects and modulates the incident first polarized light (S polarized light) and emits the second polarized light (P polarized light) that represents the display image. However, without being limited to such an example, as shown in FIG 16, the reflective liquid crystal display element 240 may reflect and modulate the incident second polarized light (P polarized light) and emit the first polarized light (S polarized light) that represents the display image.

[0225] The lens 250 magnifies the light representing the display image output from the reflective liquid crystal display element 240 and outputs it to the outside. The lens 250 is arranged so that the light representing the display image output from the reflective liquid crystal display element 240 is incident through the polarizing beam splitter 230. For example, as shown in Figs. 15 and 17, the lens 250 may be arranged so that the second polarized light (P polarized light) reflected and modulated by the reflective liquid crystal display element 240 passes through the polarizing beam splitter 230 and is incident on the lens 250. Alternatively, as shown in Fig. 16, the lens 250 may be arranged so that the first polarized light (S polarized light) reflected and modulated by the reflective liquid crystal display element 240 is reflected by the polarizing beam splitter 230 and is incident on the lens 250.

[0226] As described above, the projection display device 200 according to this embodiment uses the wire grid polarizer 1 according to this embodiment described above as the polarizing beam splitter 230. Therefore, the polarizing beam splitter 230 has excellent reflectivity for S-polarized light, transmittance for P-polarized light, and Tp×Rs characteristics for obliquely incident light with a relatively large and wide range of incident angles θ (e.g., 30 to 60°), and is excellent in the ability to separate obliquely incident light into P-polarized light and S-polarized light.

[0227] Next, specific examples of the projection display devices 200A, 200B, and 200C shown in FIGS. 15 to 17 will be described individually.

[0228] As shown in FIG. 15, a projection display device 200A according to a first specific example of this embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250.

[0229] The light emitted from the light source 210 is unpolarized and contains an equal proportion of P-polarized and S-polarized components. Therefore, if only one of the polarized lights is selected and extracted by the polarizing beam splitter 230 made of the polarizing element 1, the amount of light is reduced to about half. Therefore, the PS converter 220 converts the light emitted from the light source 210 into either the first polarized light (S-polarized) or the second polarized light (P-polarized). This makes it possible to suppress the reduction in the amount of polarized light extracted by the polarizing beam splitter 230 and improve the light utilization efficiency. For example, the PS converter 220 shown in FIG. 15 converts the light from the light source 210 into the first polarized light (S-polarized).

[0230] The light converted into S-polarized light by PS converter 220 is incident on polarizing beam splitter 230 arranged at an angle of approximately 45°. Polarizing beam splitter 230 reflects the first polarized light (S-polarized light) and emits it toward reflective liquid crystal display element 240 at an emission angle of 45°. Reflective liquid crystal display element 240 modulates and reflects the first polarized light (S-polarized light) to generate second polarized light (P-polarized light) that represents a display image, and emits the second polarized light (P-polarized light) toward polarizing beam splitter 230. The second polarized light (P-polarized light) passes through polarizing beam splitter 230 and is magnified by lens 250, and then projected onto a display surface (not shown) to display the display image.

[0231] The projection display device 200A having the above configuration includes a reflective wire-grid polarizer made of the wire-grid polarizer 1 according to this embodiment as the polarizing beam splitter 230. This makes it possible to improve the polarization separation characteristics of the polarizing beam splitter 230 for obliquely incident light and incident light with a wide incidence angle θ, and also to improve the heat dissipation and heat resistance of the polarizing beam splitter 230 and the projection display device 200A.

[0232] In contrast, a projection display device (not shown) equipped with a conventional polarizing element as a polarizing beam splitter has poor heat dissipation of the polarizing element. For this reason, it is considered that the heat resistance is insufficient from the viewpoint of long-term use, high brightness, and enlarged display. In addition, the incident angle θ of light incident on the polarizing beam splitter is not only 45°, but also any angle within a predetermined range (for example, about 45°±15°) centered on 45°. Even when obliquely incident light with a large and wide range of incident angles θ is incident on the polarizing beam splitter, the polarizing beam splitter is required to have the performance of being able to suitably separate the obliquely incident light into S-polarized light and P-polarized light regardless of the incident angle θ. However, a polarizing beam splitter using a conventional polarizing element has poor polarization separation characteristics for the above-mentioned obliquely incident light, which deteriorates the light utilization efficiency and causes problems such as uneven brightness that adversely affect the image quality of the displayed image.

[0233] In this regard, the polarizing beam splitter 230 of the projection display device 200A according to the first specific example of this embodiment has excellent polarization separation characteristics for obliquely incident light having a large and wide range of incident angles θ as described above. Therefore, the projection display device 200A can improve the light utilization efficiency and reduce brightness unevenness, thereby improving the quality of the displayed image.

[0234] Furthermore, the projection display device is not limited to the example of the projection display device 200A shown in FIG. 15 above, and the components and arrangement of the projection display device can be changed as appropriate, for example, to the projection display device 200B shown in FIG. 16 or the projection display device 200C shown in FIG. 17.

[0235] As shown in FIG. 16, a projection display device 200B according to a second specific example of this embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250.

[0236] In the projection display device 200B, the PS converter 220 converts the light from the light source 210 into the second polarized light (P polarized light). The light converted into the P polarized light by the PS converter 220 passes through a polarized beam splitter 230 arranged at an angle of about 45° and is incident on a reflective liquid crystal display element 240. The reflective liquid crystal display element 240 modulates and reflects the second polarized light (P polarized light) to generate a first polarized light (S polarized light) representing a display image, and outputs the first polarized light (S polarized light) toward the polarized beam splitter 230. The polarized beam splitter 230 reflects the first polarized light (S polarized light) and outputs it toward the lens 25 at an output angle of 45°. The first polarized light (S polarized light) is magnified by the lens 250 and then projected onto a display surface (not shown) to display the display image.

[0237] The projection display device 200B having the above configuration, like the above-mentioned projection display device 200A (see Figure 15), has excellent polarization separation characteristics for obliquely incident light, and can improve the light utilization efficiency while reducing brightness unevenness, etc., thereby improving the image quality of the displayed image.

[0238] Moreover, as shown in FIG. 17, a projection display device 200C according to a third specific example of this embodiment includes a light source 210, a polarizing beam splitter 230, a reflective liquid crystal display element 240, a lens 250, and a light absorber 260, but does not include the above-mentioned PS converter 220.

[0239] In the projection display device 200C, the unpolarized light emitted from the light source 210 is directly incident on the polarized beam splitter 230 arranged at an angle of about 45°. The polarized beam splitter 230 reflects a first polarized light (S polarized light) component of the unpolarized light and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. On the other hand, the second polarized light (P polarized light) component of the unpolarized light incident on the polarized beam splitter 230 passes through the polarized beam splitter 230 and is incident on the light absorber 260. Most of the second polarized light (P polarized light) component is absorbed by the light absorber 260, so that it is possible to prevent the unnecessary second polarized light (P polarized light) from being incident on other optical systems in the projection display device 200C.

[0240] The reflective liquid crystal display element 240 modulates and reflects the component of the first polarized light (S polarized light) incident from the polarizing beam splitter 230 to generate a second polarized light (P polarized light) representing a display image, and emits the second polarized light (P polarized light) toward the polarizing beam splitter 230. The second polarized light (P polarized light) passes through the polarizing beam splitter 230 and is magnified by the lens 250, and then projected onto a display surface (not shown), whereby the display image is displayed.

[0241] In the projection display device 200C having the above configuration, since the PS converter 220 is not installed, the second polarized light (P polarized light) component of the unpolarized light emitted from the light source 210 is absorbed by the light absorber 260 and is not used for displaying the display image. As a result, the amount of light in the display image is reduced by about half. However, there are advantages in that the cost and installation space required for the PS converter 220 can be reduced and the number of parts of the projection display device 200C can be reduced, thereby reducing the cost of the projection display device 200C and making the projection display device 200C more compact.

[0242] The above describes a specific example of the projection display device 200 that uses the reflective wire-grid polarizer 1 according to this embodiment as the polarizing beam splitter 230. Note that the projection display device is not limited to the specific examples of the projection display device 200 shown in Figs. 15 to 17, and the components and arrangement of the projection display device may be changed as appropriate, or other components may be provided as appropriate, depending on the required performance, etc.

[0243] <5. Vehicles> Next, a vehicle equipped with the image display device according to this embodiment will be described.

[0244] A vehicle (not shown) according to this embodiment is equipped with a projection display device having the wire-grid polarizer 1 according to this embodiment described above. The vehicle may be any type of automobile, such as a passenger car, a light vehicle, a bus, a truck, a racing car, a construction vehicle, or any other large vehicle, as long as the projection display device can be installed in the vehicle. In addition to these, the vehicle may be any type of vehicle, such as a motorcycle, a train, a linear motor car, or an attraction vehicle.

[0245] The vehicle according to this embodiment can project and display a display image on a display surface (for example, display surface 5 shown in FIG. 14) provided in the vehicle by using the polarizing element 1 and the projection display device. The display surface is preferably a semi-transparent plate such as the vehicle's windshield, side glass, rear glass, or combiner. However, the display surface is not limited to such examples, and may be the surface of various parts, members, in-vehicle devices, etc. provided in the vehicle, so long as it is the surface of an object onto which a display image can be projected.

[0246] The projection display device provided in the vehicle according to this embodiment is, for example, the head-up display device 100 shown in Fig. 14, or the projection display device 200 having the polarizing beam splitter 130 shown in Figs. 15 to 17. However, the projection display device is not limited to these examples, and may be various image display devices such as a projector mounted on a vehicle, a car navigation device, or a terminal device having an image display function, as long as the projection display device is capable of projecting or displaying an image.

[0247] As described above, in the head-up display device 100, as shown in FIG. 14, sunlight may enter the head-up display device 100 from outside the vehicle through the windshield (display surface 5). The heat of the sunlight may cause deterioration or failure of the display element 3. For this reason, the hybrid wire grid polarizing element 1 described above is provided in the head-up display device 100 in order to prevent the sunlight from entering the display element 3. This polarizing element 1 has a hybrid structure with high thermal conductivity, and therefore has excellent heat dissipation and heat resistance. Therefore, the polarizing element 1 can block the sunlight that has entered the head-up display device 100 from the outside and prevent it from reaching the display element 3, thereby preventing failure or damage to the display element 3. Furthermore, the polarizing element 1 has excellent heat dissipation and heat resistance, and therefore the polarizing element 1 itself can be prevented from being damaged.

[0248] 15 to 17 is installed in a vehicle, the polarizing element 1 used as the polarizing beam splitter 230 can block sunlight from the outside, thereby preventing failure or damage to other components such as the reflective liquid crystal display element 240. Furthermore, damage to the polarizing element 1 itself, which has excellent heat dissipation and heat resistance, can also be prevented.

[0249] As described above, the projection display device installed in the vehicle of this embodiment can obtain excellent polarization characteristics (such as sunlight blocking performance and polarization separation characteristics) due to the polarizing element 1, and can also realize excellent heat resistance and durability of the projection display device.

[0250] The vehicle is not particularly limited as long as it is equipped with the above-mentioned projection display device and polarizing element, and other conditions can be set and changed as appropriate depending on the performance required of the vehicle. EXAMPLES

[0251] Next, examples of the present invention will be described. However, the examples described below are specific examples given to illustrate the configuration and effects of the polarizing element 1 according to the above-described embodiment, and the present invention is not limited to the following examples.

[0252] As an example of the present invention, a model of the wire grid polarizer 1 according to the present embodiment described above was prepared, and various characteristics were simulated to evaluate the wire grid polarizer 1. For comparison with the example of the present invention, a model of a wire grid polarizer according to a conventional example was also prepared, and similarly simulated and evaluated. Note that, for ease of explanation, the following description uses the same reference symbols and symbols for the components of the polarizer (substrate 10, grid structure 20, base portion 21, convex stripe portion 22, reflective film 30, etc.) and the symbols for the dimensions of the various components in both the example and the conventional example.

[0253] The symbols used in the following description to represent various dimensions of the polarizing element 1 are as follows: P: Pitch of the ridges 22 W T : Width of the top of the ridge portion 22 (ridge portion top width) W M : Width at the center position in the height direction of the ridge portion 22 (ridge portion center width) W B : Width of the bottom of the ridge portion 22 (grid bottom width) W MAX : Maximum width of the reflective film 30 that covers the protruding stripe portion 22 (maximum grid width) H: Height of the ridge portion 22 Hx: Height of the portion of the side surface 22b of the protruding portion 22 that is covered with the reflective film 30 Dt: thickness of the reflective film 30 covering the tip 22a of the protruding portion 22 (thickness of the tip of the reflective film 30) Ds: thickness of the reflective film 30 covering the side surface 22b of the protruding portion 22 (side surface thickness of the reflective film 30) Rc: Coverage rate of the side surface 22b of the protruding portion 22 by the reflective film 30 Rr: Opening ratio of the side surface 22b of the protruding portion 22 by the reflective film 30 θ: Incident angle of incident light λ: wavelength of incident light

[0254] (Conventional Example 1) First, conventional example 1 will be described with reference to FIG.

[0255] As shown in FIG. 18(a), a model of the polarizing element 1 according to Conventional Example 1 was produced. The polarizing element 1 according to Conventional Example 1 includes a substrate 10 made of glass and a grid structure 20 made of ultraviolet-curable resin (acrylic resin). The grid structure 20 includes a base portion 21 provided along the surface of the substrate 10 and a plurality of convex streaks 22 formed in a grid pattern protruding from the base portion 21. The cross-sectional shape of the convex streaks 22 is rectangular and not tapered. The reflective film 30 covering the convex streaks 22 is an Al film. The reflective film 30 is formed so as to cover the entire tip 22a and one side surface 22b of the convex streaks 22, and a part of the base portion 21. However, the reflective film 30 does not cover the other side surface 22b of the convex streaks 22 at all. In this way, the reflective film 30 of Conventional Example 1 is formed unevenly on only one side of the convex streaks 22, and the other side of the convex streaks 22 is not covered by the reflective film 30 and is open.

[0256] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Conventional Example 1 are as follows. P: 144 nm W T : 32.5 nm W B : 32.5 nm W MAX :55nm H: 220 nm Hx: 220nm (one side), 0nm (other side) Dt: 35 nm Ds: 22.5 nm (maximum value) Rc: 100% (one side), 0% (other side) Rr: 0% (one side), 100% (other side) θ:0°~+60° λ: 430~680nm

[0257] Then, a simulation was performed by changing the incident angle θ for the model of the polarizing element 1 according to the conventional example 1 produced as described above, and the transmission axis transmittance (Tp), the reflection axis reflectance (Rs), and Tp×Rs required for a polarizing beam splitter (PBS) were calculated. The incident angle θ was set to 0° to +60°. The wavelength λ of the incident light was changed in the range of 430 to 680 nm, and the average values ​​of a plurality of Tp and Rs values ​​calculated for the incident light of each wavelength λ were used as the values ​​of Tp and Rs. The relationship between Tp, Rs, Tp×Rs, and θ calculated as described above are shown in the graphs of Figures 18(b) to (d).

[0258] As shown in Fig. 18, in Conventional Example 1, the reflective film 30 is unevenly distributed on one side of the convex stripe portion 22, and the coverage Rc of the one side is 100%. Therefore, as the incident angle θ increases, Rs gradually increases, but Tp decreases significantly, and Tp x Rs also decreases significantly. For example, in the range of θ>45°, Tp decreases to 76% or less, and Tp x Rs decreases to 68% or less. Therefore, when the polarizing element 1 according to Conventional Example 1 is used as a polarizing beam splitter, it is found that there is a problem that the polarization separation characteristics (Tp x Rs characteristics) are poor, particularly for obliquely incident light with a large incident angle θ of 45° or more, and the Tp x Rs characteristics required for a polarizing beam splitter cannot be obtained.

[0259] (Conventional Example 2) Next, the second conventional example will be described with reference to FIG.

[0260] 19(a), a model of a polarizing element 1 according to Conventional Example 2 was produced. The model of Conventional Example 2 is similar to the model of Conventional Example 1. However, in Conventional Example 2, two angles of incidence θ were used: an incidence angle (θ=0° to +60°) in a positive direction obliquely incident on one side of the convex rib portion 22, and an incidence angle (θ=0° to -60°) in a negative direction obliquely incident on the other side of the convex rib portion 22.

[0261] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Conventional Example 2 are as follows. P: 144 nm W T : 32.5 nm W B : 32.5 nm W MAX :55nm H: 220 nm Hx: 220nm (one side), 0nm (other side) Dt: 35 nm Ds: 22.5 nm (maximum value) Rc: 100% (one side), 0% (other side) Rr: 0% (one side), 100% (other side) θ: 0°~+60°, 0°~-60° λ: 430~680nm

[0262] Then, a simulation was performed for the model of the polarizing element 1 according to the conventional example 2 produced as described above, changing the incident angle θ, and calculating the transmission axis transmittance (Tp), the reflection axis reflectance (Rs), and Tp×Rs required for a polarizing beam splitter (PBS). In this case, Tp, Rs, and Tp×Rs were calculated for the cases where the incident angle θ was in the positive direction and the negative direction, respectively. Note that the values ​​of Tp and Rs were calculated by changing the wavelength λ of the incident light in the range of 430 to 680 nm, and the average values ​​of a plurality of Tp and Rs values ​​calculated for the incident light of each wavelength were used. The relationships between Tp, Rs, Tp×Rs calculated as described above and θ are shown in the graphs of Figures 19(b) to (d).

[0263] 19, in Conventional Example 2, similar to Conventional Example 1, the reflective film 30 is unevenly distributed on one side of the protruding stripe portion 22, and the coverage Rc of the one side is 100%. As a result, as shown in FIG. 19(b), in Conventional Example 2, similar to Conventional Example 1, Tp(+) significantly decreased as the incidence angle θ increased for obliquely incident light from the + direction. Furthermore, in Conventional Example 2, Tp(-) also decreased as the absolute value of the negative incidence angle θ increased for obliquely incident light from the - direction, but it can be confirmed that the degree of decrease in Tp(-) is smaller than the degree of decrease in Tp(+).

[0264] Specifically, in Conventional Example 2, when the absolute value of θ is in the range of 30° to 60°, the difference between Tp(+) and Tp(-) is 5% or more, and the difference between Tp×Rs(+) and Tp×Rs(-) is 4% or more. From this result, it was confirmed that in Conventional Example 2, left-right asymmetry exists in the polarization characteristics of polarizing element 1 depending on whether the incident direction of obliquely incident light is the + direction or the - direction.

[0265] As in the above conventional example 2, when the difference in Tp due to the difference in the incidence direction of obliquely incident light (for example, the difference between +45° and -45°) becomes large, the viewer can recognize the difference in brightness of the displayed image, and the image state becomes inappropriate. In addition, when the polarizing element 1 according to conventional example 2 is used as a polarizing beam splitter, it is found that there is a problem that the polarization separation characteristics (Tp×Rs characteristics) are poor, particularly for obliquely incident light with a large incidence angle θ of 45° or more, and the Tp×Rs characteristics required for a polarizing beam splitter cannot be obtained.

[0266] (Conventional Example 3) Next, conventional example 3 will be described with reference to FIG.

[0267] As shown in FIG. 20(a), a model of the polarizing element 1 according to Conventional Example 3 was produced. The polarizing element 1 according to Conventional Example 3 includes a glass substrate 10 and a grid structure 20 made of ultraviolet-curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of convex streaks 22 formed in a grid pattern protruding from the base portion 21. The cross-sectional shape of the convex streaks 22 is rectangular and not tapered. The reflective film 30 covering the convex streaks 22 is an Al film. The reflective film 30 is formed so as to cover most of the tip 22a and both side surfaces 22b of the convex streaks 22 (about 85%). In this way, the reflective film 30 of Conventional Example 3 covers most of the tip 22a and both side surfaces 22b of the convex streaks 22. In addition, the reflective film 30 of conventional example 3 is angular and has two angular corner portions on both the left and right ends of the top of the reflective film 30, which differs from the rounded bulging shape of the reflective film 30 of the polarizing element 1 of this embodiment described above.

[0268] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Conventional Example 3 are as follows. P: 140 nm W T :35nm W B :35nm W MAX :65nm H: 230 nm Hx: 196 nm Dt: 30 nm Ds: 15 nm (maximum value) Rc: 85% Rr: 15% θ:0°~+60° λ: 430~680nm

[0269] Thereafter, for the model of the polarizing element 1 according to Conventional Example 3 fabricated as described above, a simulation was performed by changing the incident angle θ in the same manner as in Conventional Example 1 described above, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was set to 0° to +60°. The relationship between θ and the thus calculated Tp, Rs, and Tp×Rs is shown in the graphs of FIGS. 20(b) to (d).

[0270] As shown in FIG. 20, in the conventional example 3, the covering manner is different from that in the conventional example 1, but the reflective film 30 covers most of both side surfaces 22b of the convex stripe portion 22, and the covering rate Rc is large at 85%. Therefore, in the conventional example 3, as in the conventional example 1, as the incident angle θ increases, Rs gradually increases, but Tp decreases significantly, and Tp×Rs also decreases significantly. For example, in the range of θ>45°, Tp decreases to 73% or less, and Tp×Rs decreases to 65% or less. Therefore, when the polarizing element 1 according to the conventional example 3 is used as a polarizing beam splitter, it is found that there is a problem that the polarization separation characteristic (Tp×Rs characteristic) is poor, particularly for obliquely incident light with a large incident angle θ of 45° or more, and the Tp×Rs characteristic required for a polarizing beam splitter cannot be obtained.

[0271] Example 1 Next, a first embodiment of the present invention will be described with reference to FIGS.

[0272] As shown in Fig. 21(a), a model of the polarizing element 1 according to Example 1 was produced. The polarizing element 1 according to Example 1 includes a glass substrate 10 and a grid structure 20 made of an ultraviolet curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10, and a plurality of ridge portions 22 formed to protrude in a grid pattern from the base portion 21. The cross-sectional shape of the ridge portions 22 is trapezoidal, and is tapered toward the tips 22a of the ridge portions 22.

[0273] The reflective film 30 covering the convex streak portion 22 in Example 1 is an Al film. The reflective film 30 is formed so as to cover the tip 22a and the upper side of both side surfaces 22b of the convex streak portion 22. However, the reflective film 30 does not cover the lower side of both side surfaces 22b of the convex streak portion 22 and the base portion 21. The coverage rate Rc of both side surfaces 22b of the convex streak portion 22 by the reflective film 30 is 40%. In this way, the reflective film 30 in Example 1 roundly covers and envelops the top portion (tip 22a and upper side of side surfaces 22b) of the convex streak portion 22. The surface of the reflective film 30 is approximately elliptical with a rounded shape that bulges outward, and bulges in the width direction (X direction) of the convex streak portion 22.

[0274] As a result, the grid according to the first embodiment (a structure combining the protruding stripe portion 22 and the reflective film 30) has the special tree shape described above. MAX (The width of the grid at the most bulging portion of the reflective film 30) is the width W B (the width of the convex ridge portion 22 at a height position 20% above the bottom of the convex ridge portion 22) or more.

[0275] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to the first embodiment are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B:46nm W MAX :55nm H: 220 nm Hx: 99nm Dt: 35 nm (maximum value) Ds: 22.5 nm (maximum value) Rc: 40% Rr: 60% θ:0°~+60° λ: 430~680nm

[0276] Then, a simulation was performed by changing the incident angle θ for the model of the polarizing element 1 according to Example 1 produced as described above, and the transmission axis transmittance (Tp), the transmission axis reflectance (Ts), the reflection axis transmittance (Rp), the reflection axis reflectance (Rs), and Tp×Rs required for a polarizing beam splitter (PBS) were calculated. The incident angle θ was set to 0° to +60°. Note that, as the values ​​of Tp, Rs, Ts, and Rp, the wavelength λ of the incident light was changed in the range of 430 to 680 nm, and the average values ​​of a plurality of values ​​of Tp, Ts, Rp, and Rs calculated for the incident light of each wavelength λ were used. In addition, the contrast (CR) of the transmitted light was also calculated by dividing the transmission axis transmittance (Tp) by the transmission axis reflectance (Ts) (CR=Tp / Ts).

[0277] The relationship between Tp, Rs, Ts, Rp, CR, Tp×Rs, and λ calculated as above is shown in the table of Fig. 21(b) and the graphs of Fig. 21(c) to (d). The relationship between Tp, Rs, Tp×Rs, and θ calculated as above is shown in the graphs of Fig. 22(a) to (c).

[0278] In addition, the table in Fig. 21(b) shows the average values ​​of the characteristic values ​​(Tp, Rs, Ts, Rp, CR, Tp×Rs) for multiple wavelength bands of the incident light (430-510nm, 520-590nm, 600-680nm) and the entire wavelength band of the incident light (430-680nm). The graphs in Fig. 21(c)-(d) and the graphs in Fig. 22(a)-(c) show the average values ​​of the characteristic values ​​(Tp, Rs, Ts, Rp, CR, Tp×Rs) for the entire wavelength band of the incident light (430-680nm). In addition, the graphs in Figures 22(a) to (c) also show the characteristic values ​​(Tp(+), Tp(-), Rs(+), Rs(-), Tp x Rs(+), Tp x Rs(-)) of the above-mentioned Conventional Example 2 for comparison with Example 1.

[0279] 21(a), in the model of the polarizing element 1 of Example 1, the reflective film 30 covers the tops of the convex ridges 22 and leaves the bottoms of the convex ridges 22 open, with a coverage Rc of 40%. Therefore, the grid of Example 1 (a structure combining the convex ridges 22 and the reflective film 30) has the special tree shape described above. The grid of Example 1 having such a special tree structure has excellent transmittance and polarization separation characteristics for obliquely incident light with a large and wide range of incident angles θ.

[0280] Therefore, as shown in FIG. 21, in Example 1, regardless of the wavelength λ, Tp is 80% or more and Rs is 90% or more, and it is found that high Tp and Rs can be obtained. As a result, Tp×Rs is also 72% or more, and it is found that excellent Tp×Rs characteristics can be obtained. It is also found that an excellent contrast CR of 100 or more can be obtained regardless of the wavelength λ. Therefore, it is found that Example 1 can obtain better polarization characteristics for obliquely incident light than the above-mentioned conventional examples 1 and 2.

[0281] Furthermore, as shown in FIG. 22, in Example 1, a very high value of Tp of 78% or more is ensured in a wide range of incidence angles θ from 0° to 60°. As a result, it is found that a high Tp×Rs of 73% or more can be ensured for obliquely incident light with a large and wide range of incidence angles θ (30° to 60°), and excellent polarization separation characteristics (Tp×Rs characteristics) are provided. In particular, when θ=45°, Tp is a very high value of 87%, and the value of Tp×Rs is also a very high value of 78%. Therefore, it is found that the polarizing element 1 of Example 1 can exhibit remarkably excellent transmittance and polarization separation characteristics for obliquely incident light with an incidence angle θ of 45° and its surroundings.

[0282] Furthermore, as can be seen from the comparison result between Example 1 and Conventional Example 2 shown in FIG. 22, in Conventional Example 2, as the incident angle θ increases, Tp and Tp×Rs decrease, and in particular, in the range of θ>45°, Tp and Tp×Rs decrease rapidly. In contrast, in Example 1, even if θ increases, the decrease in Tp and Tp×Rs is suppressed and high values ​​can be maintained. In particular, when θ=45°, Example 1 can obtain Tp and Tp×Rs that are 6% or more higher than the case of incidence in the + direction of Conventional Example 2, and can obtain Tp and Tp×Rs that are 10% or more higher than the case of incidence in the - direction of Conventional Example 2. Thus, in Example 1, the highest transmittance (transmittance Tp) and Tp×Rs characteristics can be obtained when θ=45°.

[0283] Moreover, with regard to the reflection axis reflectance Rs, in comparison with Conventional Examples 1 and 2, Example 1 achieves a high reflectance with no significant difference.

[0284] Moreover, in terms of the Tp×Rs characteristic required for a polarizing beam splitter (PBS), Example 1 is superior to Conventional Examples 1 and 2, and the highest Tp×Rs characteristic is obtained when the incident angle θ is 45°. Moreover, even in the range of incident angle θ=30° to 60°, Example 1 can obtain better characteristics than Conventional Examples 1 and 2, and has better Tp×Rs characteristics than Conventional Examples 1 and 2 for oblique incident light with a large and wide range of incident angles θ. Furthermore, Example 1 has a well-balanced Tp×Rs characteristic for oblique incident light with an incident angle θ in the range of 45°±15°. Therefore, when the polarizing element 1 according to Example 1 is used as a polarizing beam splitter to project an image, the brightness of the displayed image is well-balanced as seen by the observer, and the image state is also good.

[0285] As described above, when the polarizing element 1 according to the first embodiment is used as a polarizing beam splitter, it is found that the transmittance (transmittance Tp) and the polarization separation characteristic (Tp×Rs characteristic) of P-polarized light are remarkably excellent for obliquely incident light with an incident angle θ in a large and wide range of 30° to 60°, particularly for obliquely incident light of 45°. Therefore, it can be said that the polarization separation characteristic required for a polarizing beam splitter for obliquely incident light can be fully satisfied.

[0286] Moreover, it is understood that, with regard to the contrast CR of transmitted light (CR=Tp / Ts), in Example 1, an excellent contrast CR of 100 or more can be obtained.

[0287] Example 2 Next, a second embodiment of the present invention will be described with reference to FIG.

[0288] 23(a), a model of a polarizing element 1 according to Example 2 was produced. The model of Example 2 differs from the model of Example 1 above in the shape of the convex rib portion 22 and the manner of coverage by the reflective film 30. The cross-sectional shape of the convex rib portion 22 in Example 2 is triangular, and has a tapered shape that becomes thinner toward the tip 22a of the convex rib portion 22.

[0289] The reflective film 30 covering the convex streak portion 22 in Example 2 is an Al film. The reflective film 30 is formed so as to cover the tip 22a and the upper side of both side surfaces 22b of the convex streak portion 22. However, the reflective film 30 does not cover the lower side of both side surfaces 22b of the convex streak portion 22 and the base portion 21. The coverage rate Rc of both side surfaces 22b of the convex streak portion 22 by the reflective film 30 is 45%. In this way, the reflective film 30 in Example 2 roundly covers and envelops the top portion (tip 22a and upper side of side surface 22b) of the convex streak portion 22. The surface of the reflective film 30 is a substantially elliptical shape having a roundness that bulges outward, and bulges in the width direction (X direction) of the convex streak portion 22. In this way, the grid according to Example 2 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree shape, similar to Example 1.

[0290] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to the second embodiment are as follows. P: 140 nm W T :10nm W B : 40 nm W MAX :41nm H: 230 nm Hx: 103.5 nm Dt: 50 nm (maximum value) Ds: 17 nm (maximum value) Rc: 45% Rr: 55% θ:0°~+60° λ: 430~680nm

[0291] Thereafter, a simulation was performed for the model of the polarizing element 1 according to Example 2 produced as described above, varying the incident angle θ, and the transmission axis transmittance (Tp), reflection axis reflectance (Rs), and Tp×Rs required for a polarizing beam splitter (PBS) were calculated. Note that the values ​​of Tp and Rs were calculated by varying the wavelength λ of the incident light in the range of 430 to 680 nm, and the average values ​​of multiple Tp and Rs values ​​calculated for the incident light of each wavelength were used. The relationships between Tp, Rs, Tp×Rs, and θ calculated as described above are shown in the graphs of Figures 23(b) to (d).

[0292] As shown in Figure 23(a), the grid of Example 2 (a structure combining the convex stripe portion 22 and the reflective film 30) has the special tree-like shape described above, similar to that of Example 1, and therefore has excellent transmittance and polarization separation characteristics for obliquely incident light with a large and wide range of incident angles θ.

[0293] 23, in Example 2, a high Tp value of 74% or more is ensured over a wide range of incident angles θ from 0° to 45°. In particular, when θ=30° and 45°, a high Tp value of 88% or more can be ensured, and a high Tp×Rs value of 74% or more can be ensured, and it is found to have excellent polarization separation characteristics (Tp×Rs characteristics). Therefore, it is found that the polarizing element 1 of Example 2 can exhibit significantly excellent transmittance and polarization separation characteristics for obliquely incident light with an incident angle θ of 30° to 45°.

[0294] As described above, even when the shape of the convex streak portion 22 of the grid structure 20 is different from that of Example 1, it is found that good transmittance and polarization separation characteristics can be obtained as compared with Conventional Examples 1 to 3. However, when the incident angle θ is 60°, Example 1 is superior to Example 2 in Tp and Tp×Rs characteristics.

[0295] Example 3 Next, Example 3 of the present invention will be described with reference to Fig. 24. In Example 3, the relationship between the height H of the convex streak portion 22 and the polarization characteristics of the polarizing element 1 was examined.

[0296] As shown in FIG. 24(a), a model of the polarizing element 1 according to Example 3 was produced. The model of Example 3 is similar to the model of Example 1 described above. The cross-sectional shape of the convex streak portion 22 is trapezoidal, tapering toward the tip 22a of the convex streak portion 22. The grid of Example 3 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree shape, similar to Example 1. In Example 3, the height H of the convex streak portion 22 was changed stepwise in the range of 100 to 220 nm while maintaining the coverage Rc at 45%.

[0297] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to the third embodiment are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm W MAX :55nm H: 100~220nm Hx: 45~99nm Dt: 35 nm (maximum value) Ds: 22.5 nm (maximum value) Rc: 45% Rr: 55% θ :+45° λ: 430~680nm

[0298] Thereafter, for the model of the polarizing element 1 according to Example 3 produced as described above, a simulation was performed by changing the height H of the convex stripe portion 22, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was set to +45°. The values ​​of Tp and Rs were calculated by varying the wavelength λ of the incident light in the range of 430 to 680 nm and averaging the values ​​of Tp and Rs calculated for the incident light of each wavelength λ. In addition, the contrast CR of the transmitted light was also calculated by dividing Tp by Ts.

[0299] The relationships between Tp, Rs, Tp×Rs, CR, and H calculated as above are shown in the graphs of FIGS. 24(b) to (e).

[0300] As shown in Figure 24, in order to improve the various characteristics (Tp, Tp x Rs, CR) of the polarizing element 1 for obliquely incident light at 45°, it is preferable that the height H of the convex streak portion 22 be 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more.

[0301] Specifically, as shown in Fig. 24(b), when H is 160 nm or more, Tp is 80% or more, and a high transmittance is obtained, which is preferable. Furthermore, when H is 180 nm or more, Tp of 85% or more is obtained, which is more preferable. In addition, when H is 220 nm or more, Tp of 87% or more is obtained, which is particularly preferable.

[0302] As for the Tp×Rs characteristics, as shown in FIG. 24(d), if H is 160 nm or more, an excellent Tp×Rs of 70% or more can be obtained, which is preferable. Furthermore, if H is 180 nm or more, a Tp×Rs of 75% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, a Tp×Rs of 77% or more can be obtained, which is particularly preferable.

[0303] As for the contrast CR, as shown in FIG. 24(e), H should be 100 nm or more, and a CR of 40 or more can be obtained. If H is 160 nm or more, an excellent CR of 150 or more can be obtained, which is preferable. Furthermore, if H is 180 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, an excellent CR of 500 or more can be obtained, which is particularly preferable.

[0304] Example 4 Next, a fourth embodiment of the present invention will be described with reference to Fig. 25. In the fourth embodiment, the relationship between the thickness Dt of the reflective film 30 covering the tip 22a of the convex streak portion 22 (the tip thickness Dt of the reflective film 30) and the polarization characteristics of the polarizing element 1 was examined.

[0305] As shown in FIG. 25(a), a model of a polarizing element 1 according to Example 4 was produced. The model of Example 4 is similar to the model of Example 1 described above. The cross-sectional shape of the convex streak portion 22 is trapezoidal, tapering toward the tip 22a of the convex streak portion 22. The grid of Example 4 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree-like shape, similar to Example 1. In Example 4, the tip thickness Dt of the reflective film 30 was changed stepwise in the range of 5 to 35 nm.

[0306] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to the fourth embodiment are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm W MAX :55nm H: 220 nm Hx: 99nm Dt: 5 to 35 nm (maximum value) Ds: 22.5 nm (maximum value) Rc: 45% Rr: 55% θ :+45° λ: 430~680nm

[0307] Thereafter, for the model of the polarizing element 1 according to Example 4 produced as described above, a simulation was performed by changing the tip thickness Dt of the reflective film 30, and Tp, Rs, Tp×Rs, and CR were calculated. The incident angle θ was set to +45°. The relationships between Tp, Rs, Tp×Rs, CR, and Dt calculated as described above are shown in the graphs of FIGS. 25(b) to (e).

[0308] As shown in Figure 25, in order to improve the various characteristics (Tp, Tp x Rs, CR) of the polarizing element 1 for 45° oblique incident light, it is preferable that the tip thickness Dt of the reflective film 30 be 5 nm or more, and more preferably 15 nm or more.

[0309] Specifically, as shown in Fig. 25(b), it is preferable that Tp is 85% or more and a high transmittance is obtained when Dt is 5 nm or more, and as shown in Fig. 25(c), it is preferable that Rs is 85% or more and a high reflectance is obtained when Dt is 5 nm or more.

[0310] As for the Tp×Rs characteristics, as shown in FIG. 25(d), if Dt is 15 nm or more, an excellent Tp×Rs of 78% or more can be obtained, which is more preferable.

[0311] As for the contrast CR, as shown in Fig. 25(e), if Dt is 5 nm or more, an excellent CR of 100 or more can be obtained, which is preferable. Furthermore, if Dt is 15 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable.

[0312] Example 5 Next, a fifth embodiment of the present invention will be described with reference to Fig. 26. In the fifth embodiment, the relationship between the thickness Ds of the reflective film 30 covering the side surface 22b of the convex stripe portion 22 (the side surface thickness Ds of the reflective film 30) and the polarization characteristics of the polarizing element 1 was examined.

[0313] As shown in FIG. 26(a), a model of a polarizing element 1 according to Example 5 was produced. The model of Example 5 is similar to the model of Example 1 described above. The cross-sectional shape of the convex streak portion 22 is trapezoidal, tapering toward the tip 22a of the convex streak portion 22. The grid of Example 5 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree-like shape, similar to Example 1. In Example 5, the side thickness Ds of the reflective film 30 was changed stepwise in the range of 5 to 35 nm.

[0314] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to the fifth embodiment are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm W MAX :20~80nm H: 220 nm Hx: 99nm Dt: 35 nm (maximum value) Ds: 5 to 35 nm (maximum value) Rc: 45% Rr: 55% θ :+45° λ: 430~680nm

[0315] Thereafter, for the model of the polarizing element 1 according to Example 5 produced as described above, a simulation was performed by changing the side thickness Ds of the reflective film 30, and Tp, Rs, Tp×Rs, and CR were calculated. The incident angle θ was set to +45°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above, and Dt are shown in the graphs of FIGS. 26(b) to (e).

[0316] As shown in Figure 26, in order to improve the various characteristics (Tp, Tp x Rs, CR) of the polarizing element 1 for 45° oblique incident light, it is preferable that the side thickness Ds of the reflective film 30 be 10 nm or more and 30 nm or less, more preferably 12.5 nm or more and 25 nm or less, and particularly preferably 15 nm or more and 25 nm or less.

[0317] Specifically, as shown in Fig. 26(b), for Tp, if Ds is 10 nm or more and 30 nm or less, Tp is 80% or more, and a high transmittance is obtained, which is preferable. Furthermore, if Ds is 12.5 nm or more and 25 nm or less, Tp is 85% or more, and a higher transmittance is obtained, which is more preferable. Furthermore, if Ds is 15 nm or more and 20 nm or less, Tp is 87% or more, and a higher transmittance is obtained, which is particularly preferable.

[0318] As for Rs, as shown in Fig. 26(c), if Ds is 10 nm or more, Rs is 80% or more, and a high reflectance is obtained, which is preferable. Furthermore, if Ds is 12.5 nm or more, Rs is 85% or more, and a higher reflectance is obtained, which is more preferable. Furthermore, if Ds is 15 nm or more, Rs is 87% or more, and a higher reflectance is obtained, which is particularly preferable.

[0319] As for the Tp×Rs characteristics, as shown in Fig. 26(d), if Ds is 12.5 nm or more and 30 nm or less, an excellent Tp×Rs of 70% or more can be obtained, which is preferable. Furthermore, if Ds is 15 nm or more and 25 nm or less, an excellent Tp×Rs of 76% or more can be obtained, which is even more preferable.

[0320] As for the contrast CR, as shown in Fig. 26(e), Ds is required to be 10 nm or more, but if Ds is 12.5 nm or more, an excellent CR of 50 or more can be obtained, which is preferable. Furthermore, if Ds is 15 nm or more, an excellent CR of 100 or more can be obtained, which is more preferable.

[0321] Example 6 Example 6 of the present invention will now be described with reference to Fig. 27. In Example 6, the relationship between the coverage Rc of the side surface 22b of the convex stripe portion 22 by the reflective film 30 and the polarization characteristics of the polarizing element 1 was examined.

[0322] As shown in FIG. 27(a), a model of the polarizing element 1 according to Example 6 was produced. The model of Example 6 is similar to the model of Example 1 described above. The cross-sectional shape of the convex streak portion 22 is trapezoidal, tapering toward the tip 22a of the convex streak portion 22. The grid of Example 6 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree shape, similar to Example 1. In Example 6, the height Hx of the range where the reflective film 30 covers the side surface 22b of the convex streak portion 22 is changed, so that the coverage rate Rc is changed stepwise in the range of 20 to 90%.

[0323] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Example 6 are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm W MAX :55nm H: 220 nm Hx: 44~198nm Dt: 35 nm (maximum value) Ds: 22.5 nm (maximum value) Rc: 20~90% Rr: 80~10% θ :+45° λ: 430~680nm

[0324] Thereafter, for the model of the polarizing element 1 according to Example 6 produced as described above, a simulation was performed by changing the coverage Rc, and Tp, Rs, Tp×Rs, and CR were calculated. The incident angle θ was set to +45°. The relationship between Tp, Rs, Tp×Rs, CR, and Dt calculated as described above is shown in the graphs of FIGS. 27(b) to (e).

[0325] As shown in Figure 27, in order to improve the various characteristics (Tp, Tp x Rs, CR) of the polarizing element 1 for obliquely incident light at 45°, it is preferable that the coverage Rc be 25% or more and 80% or less, more preferably 30% or more and 70% or less, even more preferably 30% or more and 60% or less, and particularly preferably 40% or more and 50% or less.

[0326] Specifically, as shown in Fig. 27(b), for Tp, if Rc is 25% or more and 80% or less, Tp will be 75% or more, and a high transmittance will be obtained, which is preferable. Furthermore, if Rc is 30% or more and 70% or less, Tp will be 80% or more, and a higher transmittance will be obtained, which is more preferable. Furthermore, if Rc is 40% or more and 50% or less, Tp will be 85% or more, and a higher transmittance will be obtained, which is particularly preferable.

[0327] As for Rs, as shown in FIG. 27(c), if Rc is 20% or more, Rs becomes 85% or more, and a high reflectance can be obtained, which is preferable.

[0328] As for the Tp×Rs characteristics, as shown in FIG. 27(d), if Rc is 25% or more and 80% or less, Tp×Rs is 70% or more, which is preferable since excellent Tp×Rs characteristics can be obtained. Furthermore, if Rc is 30% or more and 70% or less, Tp×Rs is 72% or more, and if Rc is 30% or more and 60% or less, Tp×Rs is 75% or more, which is more preferable since even better Tp×Rs characteristics can be obtained. Furthermore, if Rc is 40% or more and 50% or less, Tp×Rs is 77% or more, which is particularly preferable since even better Tp×Rs characteristics can be obtained.

[0329] As for the contrast CR, as shown in Fig. 27(e), Rc should be 20% or more, but if Rc is 30% or more, an excellent CR of 100 or more can be obtained, which is preferable. Furthermore, if Rc is 40% or more, an excellent CR of 200 or more can be obtained, which is even more preferable.

[0330] Example 7 Next, Example 7 of the present invention will be described with reference to Fig. 28. In Example 7, the relationship between the thickness Ds of the reflective film 30 covering the side surface 22b of the convex stripe portion 22 (side surface thickness Ds of the reflective film 30), the incident angle θ, and the polarization characteristics of the polarizing element 1 was examined.

[0331] As shown in FIG. 28(a), a model of the polarizing element 1 according to Example 7 was produced. The model of Example 7 is similar to the model of Example 1 described above. The cross-sectional shape of the convex streak portion 22 is trapezoidal, tapering toward the tip 22a of the convex streak portion 22. The grid of Example 7 (a structure combining the convex streak portion 22 and the reflective film 30) has the above-mentioned special tree-like shape, similar to Example 1. In Example 7, the side thickness Ds of the reflective film 30 was changed stepwise in the range of 17.5 to 25 nm, while the incident angle θ was changed stepwise in the range of 0 to 60°.

[0332] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Example 7 are as follows. P: 144 nm W T :19nm WM : 32.5 nm W B :46nm W MAX : 45nm, 55nm, 60nm H: 220 nm Hx: 99nm Dt: 35 nm (maximum value) Ds: 17.5nm, 22.5nm, 25nm (maximum value) Rc: 45% Rr: 55% θ:0~+60° λ: 430~680nm

[0333] Thereafter, for the model of the polarizing element 1 according to Example 7 produced as described above, a simulation was performed by changing the side thickness Ds of the reflective film 30 and the incident angle θ, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was changed stepwise in 15° increments within the range of 0 to +60°. The relationships between Tp, Rs, Tp×Rs calculated as described above, and Dt are shown in the graphs of FIGS. 28(b) to (d).

[0334] 28, even when the side thickness Ds of the reflective film 30 is changed stepwise in the range of 17.5 to 25 nm, the polarizing element 1 exhibits good polarization characteristics (Tp, Rs, Tp×Rs) for obliquely incident light with a wide range of incident angles θ from 0° to +60°. In particular, it exhibits extremely excellent polarization characteristics for obliquely incident light with an incident angle θ of +45°.

[0335] Specifically, as shown in Fig. 28(b), even if Ds varies in the range of 17.5 to 25 nm, if θ is in the range of +30° to +60°, Tp is 75% or more and a high transmittance is obtained, which is preferable. Furthermore, if θ is +45°, Tp is 85% or more and the highest transmittance is obtained, which is more preferable.

[0336] Moreover, as shown in FIG. 28(c), Rs is preferably 85% or more in a wide range of the incident angle θ from 0° to +60°, and a high reflectance can be obtained.

[0337] As for the Tp×Rs characteristic, as shown in FIG. 28(d), even if Ds changes in the range of 17.5 to 25 nm, if θ is in the range of +30° to +60°, Tp×Rs is 70% or more, and excellent Tp×Rs characteristics are obtained, which is preferable. Furthermore, if θ is +45°, Tp×Rs is 76% or more, and the best Tp×Rs characteristics are obtained, which is more preferable. In addition, the Tp×Rs characteristics are well-balanced for obliquely incident light with an incident angle θ in the range of 45°±15°. Therefore, when the polarizing element 1 according to the seventh embodiment is used as a polarizing beam splitter to project an image, the brightness of the displayed image is well-balanced as seen by the observer, and the image state is also good.

[0338] Example 8 Next, Example 8 of the present invention will be described with reference to Fig. 29. In Example 8, the relationship between the uneven distribution ratio when the reflective film 30 covering the convex stripe portion 22 is unevenly distributed on one side and the polarization characteristics of the polarizing element 1 was examined.

[0339] As shown in Fig. 29(a), a model of a polarizing element 1 according to Example 8 was created. The model of Example 8 is similar to the model of Example 1 described above, except that the reflective film 30 is biased to one side of the convex stripe portion 22. The cross-sectional shape of the convex stripe portion 22 is trapezoidal, and is tapered toward the tip 22a of the convex stripe portion 22. The grid of Example 8 (a structure combining the convex stripe portion 22 and the reflective film 30) has the special tree-like shape described above, similar to Example 1.

[0340] In Example 8, for the left side surface 22b of the convex stripe portion 22, the side thickness Ds (left side) of the reflective film 30 covering the side surface 22b was fixed at 22.5 nm, the height of the coverage area Hx (left side) was fixed at 99 nm, and the coverage rate Rc (left side) was fixed at 45%. On the other hand, the side thickness Ds (right side) of the reflective film 30 covering the right side surface 22b of the convex stripe portion 22 was changed stepwise in the range of 0 to 22.5 nm. In accordance with this, for the right side surface 22b of the convex stripe portion 22, the height of the coverage area Hx (right side) of the right side surface 22b was changed stepwise in the range of 0 to 99 nm, and the coverage rate Rc (right side) was changed stepwise in the range of 0 to 45%. As a result, the maximum grid width W MAX changed stepwise in the range of 32.5 to 55 nm.

[0341] In addition, in Example 8, two angles of incidence θ were used: a positive angle of incidence (θ = 0° to +60°) incident obliquely onto the left side of the convex streak portion 22, and a negative angle of incidence (θ = 0° to -60°) incident obliquely onto the right side of the convex streak portion 22.

[0342] The dimensions and shapes of the various parts of the model of the polarizing element 1 according to Example 8 are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm W MAX :32.5nm, 37.5nm, 47.5nm, 55nm H: 220 nm Hx (left side): 99nm Hx (right side): 0~99nm Dt: 35 nm (maximum value) Ds (left side): 22.5 nm (maximum value) Ds (right side): 0nm, 5nm, 10nm, 22.5nm (maximum value) Rc (left side): 45% Rc (right side): 0%, 22%, 33%, 45%, Rr (left side): 55% Rc (Right side): 100%, 78%, 67%, 55% θ (left side): 0~+60° θ (right side): 0~-60° λ: 430~680nm

[0343] Thereafter, for the model of the polarizing element 1 according to Example 8 produced as described above, simulations were performed by changing Ds (right side) and Rc (right side) for the left side surface 22b of the reflective film 30, and Tp, Rs, Tp×Rs, and CR were calculated. The incident angle θ was changed stepwise in 15° increments within the range of 0 to +60°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above, and Dt are shown in the graphs of FIGS. 29(b) to (e).

[0344] As shown in Figure 29, even when the reflective film 30 is biased to one side of the convex stripe portion 22, i.e., when the grid is asymmetric, the polarizing element 1 has good polarization characteristics (Tp, Rs, Tp×Rs, CR).

[0345] Specifically, as shown in Fig. 29(b), when obliquely incident light was incident from either the + or - direction on the grid with the unevenly distributed reflective film 30, both Tp(+) and Tp(-) were 85% or more, and high transmittance was obtained on both sides of the grid. In this case, the difference between Tp(+) and Tp(-) was 3% or less, and it was confirmed that there was no significant difference between Tp(+) and Tp(-) depending on the incident direction of the obliquely incident light.

[0346] Moreover, as shown in FIG. 29(c), when obliquely incident light was incident from either the + or - direction on the grid on which the reflective film 30 was unevenly distributed, both Rs(+) and Rs(-) were 85% or higher, and high reflectance was obtained on both sides of the grid.

[0347] In addition, as shown in FIG. 29(d), in terms of the Tp×Rs characteristics, regardless of whether the oblique incident light was incident from the + or - direction on the grid on which the reflective film 30 was unevenly distributed, Tp×Rs was 75% or more, and excellent Tp×Rs characteristics were obtained.

[0348] As for the contrast CR, as shown in Fig. 29(e), excellent CR was obtained regardless of whether the oblique incident light was incident from the + or - direction on the grid with the unevenly distributed reflective film 30. Furthermore, it is preferable that Ds (right side) is 5 nm or more and the coverage (left side) is 22% or more, thereby obtaining an excellent CR of 100 or more. In addition, it is more preferable that Ds (right side) is 10 nm or more and the coverage (left side) is 33% or more, thereby obtaining an even better CR of 150 or more.

[0349] (Verification results of the shape of the reflective film: Example 9, Conventional Example 4) Next, referring to Figures 30 and 31, Example 9 of the present invention (in which the reflective film 30 is round) is compared with Conventional Example 4 (in which the reflective film 30 is square), and the results of examining the relationship between the shape of the reflective film 30 covering the convex streak portion 22 and the polarization characteristics of the polarizing element 1 are described.

[0350] As shown in FIGS. 30 and 31, a model of the polarizing element 1 according to Example 9 and a model of the polarizing element 1 according to Conventional Example 4 were fabricated.

[0351] The model of the polarizing element 1 according to Example 9 has a special tree shape, similar to the model of Example 1 described above (see FIG. 21, etc.). The grid of the polarizing element 1 according to Example 9 has a base portion 21, a convex portion 22 having a trapezoidal cross-sectional shape, and a reflective film 30 that covers the top of the convex portion 22 (the tip 22a and the upper side of the side surface 22b). However, the model of the polarizing element 1 according to Example 9 has a different coverage rate Rc of both side surfaces 22b of the convex portion 22 by the reflective film 30 compared to the model of Example 1 described above, and the coverage rate Rc of Example 9 is 45%. The reflective film 30 of Example 9 has a shape that wraps around the top of the convex portion 22. The surface of the reflective film 30 of Example 9 is a substantially elliptical shape that is rounded to the outside and bulges in the width direction (X direction) of the convex portion 22. The surface of the reflective film 30 of Example 9 has a rounded, smoothly curved shape, and does not have sharp corners or steps. Hereinafter, the reflective film 30 of Example 9 will be referred to as a round reflective film.

[0352] On the other hand, the model of the polarizing element 1 according to Conventional Example 4 is different from the model of Example 9 in the shape of the reflective film 30. The reflective film 30 of Conventional Example 4 has a rectangular shape, and has two angular corners at both the left and right ends of the top of the reflective film 30, which is different from the rounded bulging shape (round reflective film) of the reflective film 30 of Example 9 described above. Hereinafter, the reflective film 30 of Comparative Example 4 will be referred to as a rectangular reflective film. The model of the polarizing element 1 of Conventional Example 4 corresponds to the wire-grid polarizer disclosed in Patent Document 7 described above.

[0353] Thus, Conventional Example 4 is different from Example 9 in the shape of the reflective film 30, but other requirements are the same as those of Example 9.

[0354] The dimensions of the components common to the models of the polarizing element 1 of Example 9 and Conventional Example 4 are as follows. P: 144 nm W T :19nm W M : 32.5 nm W B :46nm WMAX :55nm H: 220 nm Hx: 99nm Dt: 35 nm (maximum value) Ds: 22.5 nm (maximum value) Rc: 45% Rr: 55% θ:0°~+60° λ: 430~680nm

[0355] For the models of the polarizing elements 1 according to Example 9 and Conventional Example 4 prepared as described above, simulations were performed by changing the incident angle θ, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was set to 0° to +60°.

[0356] The relationships between Tp, Rs, Tp×Rs, and θ calculated as above are shown in the graphs of FIGS. 30(b) to (d).

[0357] As shown in FIG. 30, in Example 9, a very high value of Tp of 78% or more is ensured in a wide range of incidence angles θ from 0° to 60°. As a result, it is found that a high Tp×Rs of 73% or more can be ensured for obliquely incident light with a large and wide range of incidence angles θ (30° to 60°), and excellent polarization separation characteristics (Tp×Rs characteristics) are provided. In particular, when θ=45°, Tp is a very high value of 87%, and the value of Tp×Rs is also a very high value of 78%. Therefore, it is found that the polarizing element 1 of Example 9 can exhibit remarkably excellent transmittance and polarization separation characteristics for obliquely incident light with an incidence angle θ of 45° and its surroundings.

[0358] Furthermore, as can be seen from the comparison result between Example 9 and Conventional Example 4 shown in FIG. 30, in Conventional Example 4, in the range of θ>30°, as the incident angle θ increases, Tp and Tp×Rs decrease, and in particular, in the range of θ>45°, Tp and Tp×Rs decrease rapidly.

[0359] In contrast, in Example 9, in the range of 0°≦θ≦45°, as θ increases, Tp and Tp×Rs rather increase, and high values ​​of Tp and Tp×Rs can be maintained. Furthermore, in Example 9, even if θ increases in the range of 45°<θ≦60°, the degree of decrease in Tp and Tp×Rs is significantly suppressed compared to Conventional Example 4, and high values ​​of Tp and Tp×Rs can be maintained. In particular, in the case of θ=45°, Example 9 can obtain Tp and Tp×Rs that are 5% or more higher than those of Conventional Example 4. In addition, in the case of θ=60°, Example 9 can obtain Tp and Tp×Rs that are 7% or more higher than those of Conventional Example 4. Thus, in Example 9, remarkably excellent transmittance (transmittance Tp) and Tp×Rs characteristics can be obtained in a large and wide range of incident angles θ (30° to 60°, particularly 45° to 60°).

[0360] As for Rs, in comparison with Conventional Example 4, Example 9 achieves a high reflectance with no significant difference.

[0361] Moreover, in terms of the Tp×Rs characteristic required for a polarizing beam splitter (PBS), Example 9 is superior to Conventional Example 4, and the highest Tp×Rs characteristic is obtained when the incident angle θ is 45°. Moreover, even in the range of incident angles θ=30° to 60°, Example 9 can obtain better characteristics than Conventional Example 4, and has better Tp×Rs characteristics than Conventional Example 4 for oblique incident light with a large and wide range of incident angles θ. Furthermore, Example 9 has a well-balanced Tp×Rs characteristic for oblique incident light with an incident angle θ in the range of 45°±15°. Therefore, when the polarizing element 1 according to Example 9 is used as a polarizing beam splitter to project an image, the brightness of the displayed image is well-balanced as seen by the observer, and the image state is also good.

[0362] Thus, when the polarizing element 1 is used as a polarizing beam splitter, Example 9 is found to be significantly superior in P-polarized light transmittance (transmittance Tp) and polarization separation characteristics (Tp×Rs characteristics) for obliquely incident light with a large and wide range of incident angles θ of 30° to 60°, particularly for obliquely incident light of 45°, compared to Conventional Example 4. Therefore, it can be said that the polarization separation characteristics required of a polarizing beam splitter for obliquely incident light can be fully satisfied.

[0363] As described above, Example 9 having a round reflective film 30 has a lower dependency on the incidence angle θ of obliquely incident light and is superior in transmittance of obliquely incident light and in polarization separation characteristics (Tp×Rs characteristics) as a polarizing beam splitter, compared to Conventional Example 4 having a square reflective film 30. The reason for this will be explained below with reference to FIG.

[0364] As shown in FIG. 31, the transmittance of incident light in the wire grid polarizer 1 is basically determined by the effective grid width W A and gap width W G Ratio to (W G / W A ) is determined by the grid width W A is the width of one reflective film 30 in a direction perpendicular to the traveling direction of the incident light, and the gap width W G is the width of the gap between two adjacent reflective films 30 in a direction perpendicular to the traveling direction of the incident light. As the width of the reflective film 30 (the width of the metal grid portion) per pitch of the grid structure 20 becomes smaller, the amount of incident light reflected by the reflective film 30 with the smaller width becomes smaller, and therefore the transmittance of the incident light becomes larger.

[0365] Here, as shown in Fig. 31, a case where incident light is incident on the polarizing element 1 from an oblique direction (i.e., when θ>0°) is considered. In this case, in Example 9 in which the reflective film 30 is round, the effective grid width W A becomes smaller, and the gap width W Gbecomes larger. Therefore, when obliquely incident light is incident on the polarizing element 1, the transmittance Tp of Example 9 is higher than the transmittance Tp of Conventional Example 4. As a result, the Tp×Rs characteristic of Example 9 is superior to that of Conventional Example 4. For example, when the incident angle θ of the obliquely incident light is 45°, the transmittances Tp and Tp×Rs of Example 9 are each about 5% higher than those of Conventional Example 4, and when θ is 60°, the transmittances Tp and Tp×Rs of Example 9 are each about 7% higher than those of Conventional Example 4 (see FIGS. 30(b) and (d)).

[0366] For the above reasons, Example 9 having a round reflective film 30 has a lower dependency on the incidence angle θ of obliquely incident light compared to Conventional Example 4 having a square reflective film 30, and is superior in transmittance for obliquely incident light and in polarization separation characteristics (Tp×Rs characteristics) as a polarizing beam splitter.

[0367] (Heat dissipation verification results) Next, we will compare a hybrid-type wire-grid polarizer 1 made of inorganic and organic materials according to an embodiment of the present invention with a film-type wire-grid polarizer made of organic materials according to a conventional example, and describe the results of examining the heat dissipation properties of polarizer 1.

[0368] As described above, in the wire grid polarizer 1 according to this embodiment, the substrate 10 is made of an inorganic material such as glass that has excellent heat resistance. Furthermore, the base portion 21 and the multiple convex portions 22 of the grid structure 20 provided on the substrate 10 are integrally formed from a heat-resistant organic material. In this way, the wire grid polarizer 1 according to this embodiment is a hybrid polarizer that combines organic and inorganic materials. Therefore, the thermal resistance R[m 2 Since the heat dissipation coefficient [kPa] is small and heat can be efficiently dissipated from the grid structure 20 to the substrate 10, it is considered that the heat dissipation property is excellent.

[0369] On the other hand, conventional film-type wire-grid polarizers are mainly made of organic materials and therefore have low heat resistance (around 100°C).In addition, the total thickness of the organic material layer consisting of the substrate (base film), double-sided tape (OCA), and grid structure is large, which is likely to increase the thermal resistance R of the organic material layer.

[0370] Therefore, the hybrid wire-grid polarizer 1 according to this embodiment has superior heat resistance and heat dissipation properties compared to conventional film-type polarizers made of organic materials (heat resistance: about 100° C.), and has heat resistance in high-temperature environments up to about 200° C., for example. It is therefore believed that the hybrid wire-grid polarizer 1 according to this embodiment can achieve excellent polarization characteristics while also exhibiting good heat dissipation characteristics.

[0371] Therefore, an embodiment of the hybrid type wire grid polarizer of the present invention and a conventional film type wire grid polarizer were actually fabricated, and their thermal resistance R and heat dissipation properties were examined.

[0372] Table 1 shows the types of common substrate materials and their thermal conductivity λ [W / m K]. Table 2 shows the thickness of each layer made of an organic material (PMMA) and the total thickness of multiple layers made of an organic material (PMMA) (total thickness D ALL ), thermal resistance R[m 2 ·K / W] is shown.

[0373] [Table 1]

[0374] [Table 2]

[0375] As shown in Table 2, in the hybrid type polarizing element 1 according to the embodiment, the base portion 21 and the ridge portion 22 constituting the grid structure 20 are made of an organic material, and the substrate is made of an inorganic material. On the other hand, in the film type polarizing element according to the conventional example, the substrate, the base portion constituting the grid structure, and the double-sided tape for bonding the base portion and the substrate are all made of organic materials. Here, PMMA (Poly Methyl Methacrylate) was used as the organic material. As a result, the total thickness D of the PMMA material of the hybrid type polarizing element 1 according to the embodiment is 1.2 mm. ALL On the other hand, the total thickness D of the PMMA material of the conventional film-type polarizing element is 30200 [nm]. ALL is 255000 [nm], and D in the example ALL is significantly larger than

[0376] As shown in Table 1, the thermal conductivity λ of PMMA is 0.21 [W / m K]. The thermal resistance R is the sum of the thickness D ALL " by "thermal conductivity λ" (R = D ALL Therefore, the thermal resistance R of the grid structure 20 of the hybrid polarizing element 1 according to the embodiment is 0.000144 [m 2 On the other hand, the thermal resistance R of the conventional film-type polarizing element is 0.001214 [m 2 ·K / W].

[0377] Therefore, by using the hybrid type polarizing element 1 according to the embodiment of the present invention, the value of the thermal resistance R of the grid structure 20 made of PMMA material can be reduced to about 1 / 8.4 compared to the film type polarizing element according to the conventional example. Therefore, according to the hybrid type polarizing element 1 according to the embodiment of the present invention, the heat of the grid structure 20 made of an organic material (e.g. PMMA) can be efficiently released to the outside via the substrate 10 made of an inorganic material that has better heat resistance and heat dissipation than inorganic materials, and the heat can be dissipated. Therefore, the hybrid type polarizing element 1 according to the embodiment of the present invention has very excellent heat resistance and heat dissipation compared to the conventional example.

[0378] In the above embodiment, PMMA is used as the material of the grid structure 20, but the material is not limited to this example, and various organic materials other than PMMA may be used as the material of the grid structure of the present invention.

[0379] Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Industrial Applicability]

[0380] According to the present embodiment, it is possible to provide a polarizing element having good polarization characteristics, excellent transparency for light over a wide range of incident angles without causing deterioration in heat dissipation and manufacturing costs, and a manufacturing method for the polarizing element. Also, according to the present embodiment, it is possible to provide a projection display device having excellent polarization characteristics and heat resistance, and a vehicle equipped with the projection display device. [Explanation of symbols]

[0381] 1. Wire grid polarizer 2 light source 3. Display element 4 reflector 5 Display surface 6 Cover part 10 Substrate 20 Grid Structure 21 Base 22 Convex portion 23 Grid structure materials 24 Recess 30 Reflective film 40 Protective film 50 Heat dissipation material 60 Master 61 Master Substrate 62 Metal film for master 63 Convex 64 Release film coating 65 Groove 70 Resist Mask 80 Metal Film 100 Head-up display device 200 Projection display device 210 Light source 220 PS Converter 230 Polarizing Beam Splitter 240 Reflective Liquid Crystal Display 250 Lens 260 Light absorber TS Board Thickness TB Base thickness P: Pitch of the ridges H Height of the ridge Hx Height range where the reflective film covers the side of the convex part Ds Side thickness of the reflective film Dt Thickness of the tip of the reflective film W MAX Maximum width of the reflective film that covers the convex portion (maximum grid width) W B Width of the bottom of the ridge (grid bottom width) W T Width of the top of the ridge (width of the top of the ridge) W A Effective Grid Width W G Gap Width

Claims

1. A vehicle equipped with a projection display device, The projection display device includes: A light source; a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle of 30° or more and 60° or less, and splitting the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element that is disposed so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident thereon, and that reflects and modulates the incident first polarized light or the incident second polarized light; a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter; Equipped with the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and upper sides of both sides of the protruding rib portion, but does not cover the lower sides of both sides of the protruding rib portion or the base portion; The surface of the functional film that covers the protruding portion is rounded and bulges in the width direction of the protruding portion, a cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film has a constricted portion in which the width in the width direction of the entire convex structure is narrowed immediately below a lower end of the functional film that covers the convex streak portion, When the coverage rate (Rc) of the side surface of the convex streak portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the convex streak portion covered by the functional film to the height (H) of the convex streak portion, A vehicle, wherein the coverage rate (Rc) is 30% or more and 70% or less.

2. 2. The vehicle according to claim 1, wherein the wire grid polarizer is a hybrid wire grid polarizer in which the substrate made of the inorganic material and the grid structure made of the organic material are combined.

3. The maximum width (W ＭＡＸ ) is the width (W) of the protruding portion not covered by the functional film at a position 20% above the bottom of the protruding portion. Ｂ 2. The vehicle according to claim 1, wherein said first and second wheels are arranged in a first direction and a second direction.

4. The product (Tp x Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of light incident on the wire grid polarizer at an incident angle of 45° is 70% or more. The vehicle according to any one of claims 1 to 3.

5. The vehicle according to any one of claims 1 to 4, wherein the height (H) of the convex stripe is 160 nm or more.

6. The vehicle according to any one of claims 1 to 5, wherein the thickness (Dt) of the functional film covering the tip of the protruding portion is 5 nm or more.

7. The vehicle according to any one of claims 1 to 6, wherein the thickness (Ds) of the functional film covering the side surface of the protruding streak portion is 10 nm or more and 30 nm or less.

8. The vehicle according to any one of claims 1 to 7, wherein the thickness (TB) of the base portion is 1 nm or more.

9. The vehicle according to any one of claims 1 to 8, wherein the cross-sectional shape of the convex rib portion in a cross section perpendicular to the reflection axis direction of the wire grid polarizer is a trapezoid, a triangle, a bell shape, or an ellipse whose width narrows as it moves away from the base portion.

10. The vehicle according to any one of claims 1 to 9, wherein the wire grid polarizer further comprises a protective film formed so as to cover at least a surface of the functional film.

11. The vehicle of claim 10 , wherein the protective coating comprises a water-repellent coating or an oil-repellent coating.

12. The vehicle according to any one of claims 1 to 11, wherein the functional film further comprises a dielectric film.

13. θ is the absolute value of the incidence angle of incident light with respect to the wire grid polarization element, and the incidence angle when incident light is incident from the front side of the grid structure is defined as 0°, the incidence angle when incident light is incident from a direction inclined to one side in the width direction of the ridge portion of the grid structure is defined as a positive angle, and the incidence angle when incident light is incident from a direction inclined to the other side in the width direction of the ridge portion of the grid structure is defined as a negative angle, When θ is 30° or more and 60° or less, The vehicle according to any one of claims 1 to 12, wherein a difference between a transmission axis transmittance (Tp(+)) of incident light having an incident angle of +θ to the wire grid polarization element and a transmission axis transmittance (Tp(-)) of incident light having an incident angle of -θ is within 3%.

14. The vehicle according to any one of claims 1 to 13, wherein the functional film is a reflective film that reflects incident light.

15. A light source; a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle of 30° or more and 60° or less, and splitting the incident light into a first polarized light and a second polarized light; a reflective liquid crystal display element that is disposed so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident thereon, and that reflects and modulates the incident first polarized light or the incident second polarized light; a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter; Equipped with the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and upper sides of both sides of the protruding rib portion, but does not cover the lower sides of both sides of the protruding rib portion or the base portion; The surface of the functional film that covers the protruding portion is rounded and bulges in the width direction of the protruding portion, a cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film has a constricted portion in which the width in the width direction of the entire convex structure is narrowed immediately below a lower end of the functional film that covers the convex streak portion, When the coverage rate (Rc) of the side surface of the convex streak portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the convex streak portion covered by the functional film to the height (H) of the convex streak portion, A projection display device, wherein the coverage rate (Rc) is 30% or more and 70% or less.

16. The projection display device according to claim 15 , further comprising a heat dissipation member provided around the wire grid polarizer.

17. A polarizing beam splitter provided in a projection display device, comprising: the polarizing beam splitter is composed of a wire grid polarizing element, The wire grid polarizer comprises: A substrate made of an inorganic material; a grid structure made of an organic material, the grid structure having a base portion provided on the substrate and a plurality of protruding portions protruding from the base portion, the grid structure being integrally formed; A functional film made of a metal material and covering a part of the protruding portion; Equipped with The protruding portion has a tapered shape whose width narrows as it moves away from the base portion, the functional film covers the tip and upper sides of both sides of the protruding rib portion, but does not cover the lower sides of both sides of the protruding rib portion or the base portion; The surface of the functional film that covers the protruding portion is rounded and bulges in the width direction of the protruding portion, a cross-sectional shape of the entire convex structure composed of the convex streak portion and the functional film has a constricted portion in which the width in the width direction of the entire convex structure is narrowed immediately below a lower end of the functional film that covers the convex streak portion, When the coverage rate (Rc) of the side surface of the convex streak portion by the functional film is the ratio of the height (Hx) of the portion of the side surface of the convex streak portion covered by the functional film to the height (H) of the convex streak portion, A polarizing beam splitter, wherein the coverage (Rc) is 30% or more and 70% or less.

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