JP4696783B2 - Polarized light separating film, method for producing polarized light separating film, and liquid crystal display device - Google Patents

Description

  The present invention relates to a polarization separation film, a method for producing a polarization separation film, and a liquid crystal display device, and in particular, a polarization separation film that has excellent polarization separation performance and can be produced by a simple process, a method for producing a polarization separation film, and The present invention relates to a liquid crystal display device using the polarized light separating film.

  A wire grid polarizer is known as a small and thin polarization separation element (see Non-Patent Document 1). In the wire grid polarizer, fine wires made of metal or the like are arranged substantially in parallel at intervals smaller than the wavelength of the electromagnetic wave to be polarized. The wire grid polarizer having such a configuration has a function of reflecting electromagnetic waves that vibrate in a direction parallel to the wire and transmitting electromagnetic waves that vibrate in a direction perpendicular to the vibration direction. A wire grid polarizer has a relatively simple structure compared to other polarizers, but has a high contrast indicating the ratio between the transmittance of polarized light that is transmitted and the transmittance of polarized light that is not transmitted, and transmits polarized light. The transmittance can be increased, and the polarization separation performance is excellent.

  However, as described above, in the wire grid polarizer, it is necessary to arrange the fine wires at intervals smaller than the wavelength of the target electromagnetic wave. In this case, it is difficult to adjust the distance between the fine wires. In order to form such a wire grid structure, it is generally necessary to etch a metal thin film or the like into a wire grid shape by a low-throughput process such as electron beam drawing, which takes time. Therefore, there is a problem that the manufacture of such a wire grid polarizer is complicated.

  Therefore, Patent Document 1 proposes a polarization separation film using a resin film as a substrate as a wire grid polarizer that is easy to manufacture. Such a polarized light separating film is manufactured by forming a metal thin film on a transparent resin film and then heating and stretching the resin film. Thereby, a crack generate | occur | produces in a metal thin film along the direction orthogonal to an extending | stretching direction, and a polarization separation film can form an anisotropic-shaped metal part (wire grid structure) on a resin film.

JP 2001-074935 A H. Hertz, “Electric Waves”, McCillan & Company Ltd. London, 1893, p. 177

  However, in the wire grid structure of the polarization separation film manufactured by such a method, it is difficult to control the period, thickness, direction, length, etc. of the fine wires, and it is difficult to develop high polarization separation performance. is there.

  An object of the present invention is to improve the light use efficiency by utilizing a polarization separation film that is excellent in polarization separation performance and can be easily produced, a method for producing the polarization separation film, and such a polarization separation film. It is an object of the present invention to provide a liquid crystal display device capable of achieving the above.

  The polarized light separating film of the present invention has a substrate made of a transparent and long resin film having a plurality of rows of grooves extending substantially parallel to each other on the surface, and a position facing the surface of the substrate. A light-absorbing thin film layer formed so as to cover the entire surface of the substrate including the groove portion, and in the following condition (1) and in the vertical section of the polarized light separating film, the following condition (2) It is characterized by satisfying-(5).

(1) n ₁ is 2.5 or more, or k ₁ is 1.5 or more.

(2) −0.1δ <(h ₀ −h ₁ )

Here, h ₀ indicates the depth of the groove formed on the surface of the substrate. h ₁ represents the thickness of the light-absorbing thin film layer. δ represents λ ₀ / (2π ² n ₁ ² k ₁ ) ^1/2 . n ₁ and k ₁ represent the real part and the imaginary part of the complex refractive index at the wavelength λ ₀ in the light-absorbing thin film layer, respectively. λ ₀ indicates the wavelength of the target light in vacuum.

(3) The average angle θ with respect to the height direction of the groove portion of the angle on the groove portion side formed by a straight line corresponding to the side surface portion of the groove portion and a straight line representing the substrate surface is 60 to 90 °. The average angle θ is expressed by the following formula (A).

Here, z indicates a distance in the height direction when the bottom surface of the groove portion is 0 height (h ₀ is the uppermost portion of the groove portion). θ (z) represents the angle at the height z. In other words, the formula (A) shows the average value of the angle obtained by dividing the h ₀ by integrating the θ as a function of z.

(4) d <(λ ₀ / n ₀ )

  Here, d shows the space | interval of the said adjacent groove part.

(5) 0.1d <t <0.8d
Here, t represents the average width of the groove.

According to the present invention, the polarization separation performance can be enhanced by forming the groove having a shape satisfying the above (1) to (5) on the substrate.
In addition, for example, a predetermined groove portion is continuously formed in a transparent and long resin film by a relatively simple process such as embossing, and light absorption of a metal or the like with respect to the substrate on which the groove portion is formed. Since it is a simple structure which formed the thin film layer by vapor deposition etc., a polarization separation film can be manufactured easily. Furthermore, when viewed from the position facing the substrate, the light-absorbing thin film layer may be formed from the front with respect to the surface of the substrate so as to cover the entire surface of the substrate including the groove portion. Therefore, it is not necessary to perform a complicated process such as vapor deposition from an oblique direction, and manufacturing efficiency can be increased.

  In such a polarization separation film, the light-absorbing thin film layer may also be formed on the side surface portion of the groove. According to such a configuration, the thickness of the light-absorbing thin film layer formed on the surface of the substrate can be reduced to about ½ or less as compared with the case of the conventional wire grid structure. Efficiency can be increased.

  At this time, the light-absorbing thin film layer may be continuously formed across the surface of the substrate and the side surface portion of the groove. According to such a configuration, the adhesion between the substrate and the light-absorbing thin film layer is enhanced, and the polarization separation performance can be stably exhibited.

  The above polarized light separation film may further include a protective layer provided on the surface side of the light-absorbing thin film layer. According to such a configuration, since the light-absorbing thin film layer is covered with the protective layer, the light-absorbing thin film layer is not exposed. For this reason, the handleability of the polarization separation film is improved, and a decrease in polarization separation performance due to the light-absorbing thin film layer peeling off from the substrate can be reliably prevented.

  In the above polarized light separating film, the light-absorbing thin film layer may be made of aluminum. In this case, a high performance polarized light separating film can be produced with high efficiency.

  The method for producing a polarized light separating film of the present invention includes a substrate made of a transparent and long resin film having a plurality of rows of grooves extending substantially parallel to each other on the surface, and a position facing the surface of the substrate. A light-absorbing thin film layer formed so as to cover the entire surface of the substrate including the groove portion, and in the condition (1) and the vertical sectional view, (2) to (5) An embossing step of forming a groove on the surface of the substrate by pressing a mold on which the predetermined pattern is formed, and the light-absorbing thin film on the surface of the substrate on which the groove is formed And a thin film forming step of forming a layer.

  According to the present invention, for example, after forming a groove on the surface of a resin film by continuously passing a transparent and long resin film through an embossing roll corresponding to a mold on which a predetermined pattern is formed (embossing step) ), A light-absorbing thin film layer can be continuously formed on the surface of the substrate by vapor deposition or the like (light-absorbing thin film layer forming step). For this reason, a polarization separation film can be manufactured efficiently.

  The present invention is a liquid crystal display device comprising a light source, a first absorption polarizer, a liquid crystal cell, and a second absorption polarizer in this order, the light source and the first absorption polarization The polarization separation film is provided between the optical element and the child. According to the present invention, since the light emitted from the light source by the polarization separation film can be used effectively, a high-brightness liquid crystal display device can be provided.

  According to the present invention, a substrate comprising a resin film and processed into a predetermined shape is used, and by providing a light-absorbing thin film layer on the surface of the substrate, the polarization separation performance is excellent and simple. There is an effect that it can be manufactured by a process. In addition, the use of such a polarized light separation film for a liquid crystal display device has an effect that the light use efficiency can be further enhanced.

  The polarized light separating film of the present invention is a substrate comprising a transparent and long resin film having a plurality of grooves extending substantially parallel to each other on the surface, and a position facing the surface of the substrate. The light-absorbing thin film layer is formed so as to cover the entire surface of the substrate including the groove portion, and the shape of the groove portion satisfies a predetermined condition.

The substrate is configured to include a transparent and long resin film. On the surface of the substrate, a plurality of rows of one-dimensional lattice-shaped grooves extending substantially parallel to each other are formed. The resin film has a light transmittance of 80% or more alone and preferably 86% or more as optical properties (values for all wavelengths of light when used as a polarizer). Moreover, the haze of a resin film is 2.0% or less, and it is preferable that it is 1.0% or less. The complex refractive index of the resin film is preferably such that the real part n ₀ is 1.4 to 1.8 and the imaginary part k ₀ is substantially zero.

  Further, the substrate is preferably formed in a substantially flat shape, and may be formed in a curved surface as a whole. Further, the substrate is formed in a long shape having a length of about 5 times or more in the width direction, and preferably has a length of 10 times or more in the width direction. Specifically, the substrate is preferably wound in a roll shape and has a length enough to be stored or transported.

  As a material constituting the resin film, a resin having an alicyclic structure, a chain olefin polymer such as polyethylene or polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, Various transparent plastics such as amorphous polyolefin, modified acrylic polymer, and epoxy resin can be used. These may be used alone or in combination of two or more. Among these, a resin or a chain olefin polymer having an alicyclic structure is preferable, and has an alicyclic structure such as a norbornene polymer resin from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. Resins are more preferred. As the substrate, a laminate in which the resin film is bonded to quartz or optical glass can also be used.

  The light-absorbing thin film layer is formed so as to cover the entire surface of the substrate including the groove when viewed from a position facing the surface of the substrate. Note that the entire surface of the substrate including the groove portion is not the entire surface in a strict sense, but when considering a plan view in a plane parallel to the surface of the substrate, the region covered with the light-absorbing thin film layer is This includes the case where it is approximately 95% or more of the total area of the substrate surface. If the covered area is smaller than about 95%, the polarization separation performance may not be sufficiently exhibited.

The material used for the light-absorbing thin film layer is preferably a material having a large difference between the absolute values of the real part and the imaginary part of the complex refractive index, and at least one of these values being large. In particular,
Examples include metals and semiconductors. Metals include magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, tungsten, iridium, platinum, gold, Examples include thallium. These can be used alone or in combination of two or more. Among these, magnesium, aluminum, chromium, ruthenium, rhodium, silver, indium, tin, antimony, and gold are preferable. Examples of the semiconductor include single element semiconductors such as silicon and germanium, and compound semiconductors such as GaAs, InP, SiGe, GaTZn ₃ P ₂ , and Pb _1-x Sn _x Te. Among these, silicon, SiGe, GaTZn ₃ P ₂ , and Pb _1-x Sn _x Te are preferable.

In the present invention, it is necessary to satisfy a special relationship with respect to the shape of the groove, the thickness of the light-absorbing thin film layer, the complex refractive index, and the like. Specifically, the following conditions (1) to (5) are satisfied. There is a need.

(1) n ₁ is 2.5 or more, or k ₁ is 1.5 or more.

(2) −0.1δ <(h ₀ −h ₁ )

(3) The average angle θ calculated by the following formula (A) is 60 to 90 °.

(4) d <(λ ₀ / n ₀ )

(5) 0.1d <t <0.8d

Note that h ₀ indicates the depth of the groove formed on the surface of the substrate. h ₁ represents the thickness of the light-absorbing thin film layer. δ represents λ ₀ / (2π ² n ₁ ² k ₁ ) ^1/2 . n ₁ and k ₁ represent the real part and the imaginary part of the complex refractive index at the wavelength λ ₀ in the light-absorbing thin film layer, respectively. λ ₀ indicates the wavelength of the target light in vacuum.

Further, z represents a distance in the height direction when the bottom surface of the groove portion is 0 height (h ₀ is the uppermost portion of the groove portion). θ (z) indicates an angle on the groove side between a straight line corresponding to the side surface portion of the groove and a straight line representing the substrate surface at height z. When the side surface portion of the groove portion is not a straight line, the average angle θ is obtained by dividing the side surface portion into minute portions, and the angle formed between the tangent line at each minute portion and the straight line indicating the substrate surface at that position is the bottom surface of the groove portion ( It is an angle calculated as an average value obtained by integrating in the height direction from the height 0) to the uppermost portion of the groove (height h ₀ ). In addition, when the side surface portion of the groove has a shape that is almost a straight line, the average angle θ is the angle formed by the straight line connecting the bottom of the side surface portion and the top of the side surface portion and the substrate surface in the vertical cross-sectional shape It is good.

  Moreover, d shows the space | interval of an adjacent groove part, and t shows the average width | variety of a groove part.

  When the irradiated light includes a plurality of wavelengths, the polarization separation performance of the polarization separation film, that is, good contrast can be maintained by satisfying such a condition for all wavelengths.

Further, as the groove portions of the present polarized light separation film, it is preferable that the groove portions having the same shape are arranged in parallel and at the same interval from the viewpoint of uniformity of polarization performance, stability, etc., but about 10 to 20% each. There may be a shape error. In this case, each symbol h ₀ , h ₁ , θ, d, t, etc. representing the shape of the polarization separation film is expressed as an average value.

Here, the dimensions of these symbols will be briefly described with reference to FIG.
FIG. 2 is a vertical sectional view showing a part of the polarization separation film according to the first embodiment of the present invention. As shown in FIG. 2, the polarization separation film 12 includes a substrate a having a plurality of rows of grooves Y extending substantially parallel to each other on the surface, and a light-absorbing thin film layer b formed on the surface side of the substrate a. Have. In FIG. 2, the groove Y is formed in a reverse isosceles trapezoidal shape with a larger upper side than a lower side. Since the groove Y has an inverted isosceles trapezoidal cross section, the light-absorbing thin film layer b covers the entire surface of the substrate a including the groove Y when viewed from a position facing the surface of the substrate a. It is continuously formed over the surface of the substrate a and the surface of the groove Y (side surface portion and bottom surface). When such a groove Y having an inverted isosceles trapezoidal shape in cross section is formed in the substrate a, the values of the symbols h ₀ , θ, and d are shown as the dimensions of the respective positions shown in FIG. The thickness h ₁ of the light-absorbing thin film layer is obtained as an average value of the thickness on the surface of the substrate and the thickness on the bottom surface of the groove.

  The width t of the groove of the present invention is an average value of the width of the groove with respect to the height direction of the groove. If expressed as a mathematical formula, it is represented by the following formula (B).

  Here, t (z) represents the width of the groove at the position z. For example, as shown in FIG. 2, when the cross-sectional shape of the groove is an inverted isosceles trapezoid, the width of the groove at the intermediate position in the height direction of the groove is the width t of the groove.

Here, the depth h ₀ of the groove is preferably larger than the thickness h ₁ of the light-absorbing thin film layer. The imaginary part k ₁ of the complex refractive index of the light-absorbing thin film layer at the wavelength λ ₀ is preferably 2 or more, and more preferably 3 or more. By setting h ₀ , h ₁ , and k ₁ in such ranges, the polarization separation performance can be improved.

  Further, the average angle θ indicating the integral average angle of the angle θ (z) is preferably 70 to 90 degrees, and more preferably 80 to 90 degrees. Further, the width t of the groove is preferably 0.2d <t <0.7d, and more preferably 0.25d <t <0.6d. By setting the average angle θ and the width t in the above ranges, there are advantages that the polarization separation performance can be improved and the production of the polarization separation film can be facilitated.

  In the present invention, for example, as shown in FIG. 2, the light-absorbing thin film layer is preferably formed also on the side surface portion of the groove portion, and is formed continuously over the surface of the substrate and the side surface portion of the groove portion. More preferably. By forming the light-absorbing thin film layer also on the side surface portion of the groove, the thickness of the light-absorbing thin film layer as a whole can be reduced while having a sufficient polarization separation function. For this reason, the effort concerning vapor deposition of a light-absorbing thin film layer can be reduced, and manufacture of a polarization separation film becomes easy. Further, by continuously forming the light-absorbing thin film layer, the adhesion between the substrate and the light-absorbing thin film layer is improved, and the same polarization separation performance can be exhibited in any region of the polarization separation film, thereby stabilizing the quality. Moreover, since it becomes easy to form a light-absorbing thin film layer uniformly in a large area, it is suitable also in manufacture.

However, the polarization separation film of the present invention may be as shown in FIG.
FIG. 1 is a vertical sectional view showing a part of a polarized light separation film according to a second embodiment of the present invention. As shown in FIG. 1, the polarization separation film 11 is different from the polarization separation film 2 shown in FIG. That is, in FIG. 1, the groove part X is formed in a rectangular cross section. In this case, the light-absorbing thin film layer b covers the entire surface of the substrate a including the groove portion X when viewed from a position facing the surface of the substrate a, that is, the surface of the substrate a and the groove portion X. Only formed on the bottom. In other words, the light-absorbing thin film layer b is not formed on the side surface portion of the groove X. When such a groove X having a rectangular cross section is formed in the substrate a, the symbols h ₀ , h ₁ , d, and t indicate the dimensions of the respective positions shown in FIG.

  By the way, in this invention, the protective layer may be provided in the surface side of the light-absorbing thin film layer from a viewpoint of maintaining the shape of a groove part. The protective layer may be transparent, and specifically, a resin having an alicyclic structure, a chain olefin polymer such as polyethylene or polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone. And a transparent plastic layer made of polyethersulfone, amorphous polyolefin, modified acrylic polymer, epoxy resin, and the like, and a transparent inorganic layer made of quartz, various optical glasses, and the like.

  The method of laminating the transparent protective film is not particularly limited, but a method of laminating a protective film using a laminator, a method of applying and curing various optical adhesives on the market, a physical vapor deposition method, a chemical vapor deposition method, etc. And so on.

Next, a method for producing the polarization separation film of the present invention will be described.
The polarized light separation film of the present invention is a substrate on which grooves are formed after a plurality of grooves are formed on the surface of the substrate (embossing process) by pressing a transfer mold, which is a mold on which a predetermined pattern is formed. It is manufactured by forming a light-absorbing thin film layer on the surface (thin film forming step).

The transfer mold is a mold having a pattern opposite to the intended groove shape on the surface, and the shape may be a flat plate, but a roll shape is preferred.
As a method for transferring the groove portion to the substrate, for example, the resin film is pressed and passed between a roll-shaped transfer mold and a rubber roll, and a reverse groove-shaped pattern (target groove shape) on the surface of the transfer mold is resin film. The method of transferring to above is mentioned. At this time, the transfer conditions such as the clamping pressure, the transfer mold temperature, the rubber roll temperature, the film substrate temperature, and the film feed speed may be appropriately selected.

  The material used for the mold is not particularly limited, but the mold surface is preferably formed of a material having an appropriate hardness. For example, a metal film formed by electrodeposition or electroless plating is made of copper, Nickel, nickel-phosphorus alloy, palladium and the like are preferable. The method for producing the transfer mold is not particularly limited. For example, a tool having the same pattern shape as the target groove shape at the tip is created and formed on the surface of the mold member with a precision micromachining machine using the tool. The method of doing is mentioned.

Examples of the method for forming the light-absorbing thin film layer include physical vapor deposition and chemical vapor deposition. The vapor deposition conditions may be appropriately selected according to the material constituting the light-absorbing thin film and the thickness thereof. By forming the light-absorbing thin film layer in this way, the light-absorbing thin film is continuously formed along the surface of the substrate including the groove as shown in FIG. At this time, the film thickness formed on the side surface is smaller than the film thickness formed on the surface of the substrate and the bottom surface of the groove portion. Specifically, the average film thickness formed on the side surface portion of the groove portion is approximately It is proportional to cos θ. Further, by depositing a light-absorbing thin film layer on the surface of the substrate, as shown in FIG. 1, the light-absorbing thin film is formed in a stepped grid pattern on the surface of the substrate and the bottom surface of the groove.
As described above, the polarization separation film of the present invention is produced.

Here, an antireflection film may be provided on the back surface of the substrate (that is, the surface opposite to the light-absorbing thin film). As the antireflection film, MgF ₂ film, SiO ₂ film, and TiO ₂ film are preferable, and a laminated film including a plurality of these films is more preferable, and the light transmittance in the wavelength range of 400 to 700 nm is 99% or more. More preferred.

  In the polarization separation film as described above, in the light incident on the polarization separation film, the polarized light in the direction parallel to the longitudinal direction of the groove portion is regarded as the light-absorbing medium and the direction perpendicular to the longitudinal direction of the groove portion. The polarized light separation film is almost regarded as a dielectric. Therefore, it is possible to exhibit a polarization separation function that reflects and absorbs one polarized light and transmits the other polarized light in the incident light.

  The polarized light separation film as described above can be used for various applications, and in particular, can be suitably used as a brightness enhancement film for a liquid crystal display device. If it is used for such applications, a liquid crystal display device excellent in brightness with respect to light of various wavelengths and high contrast can be manufactured, and can be used in many display devices such as personal computers and televisions.

Here, a liquid crystal display device provided with the polarization separation film of the present invention will be described.
FIG. 3 is a schematic view showing a liquid crystal display device provided with the polarization separation film of the present invention. As shown in FIG. 3, the present liquid crystal display device includes a reflector W, a light source L, a diffuser D, a polarization separation film I, an absorption polarizer P1, a liquid crystal cell LC, and an absorption polarizer P2. Are arranged in this order. That is, the polarization separation film I is provided at a position between the light source L and the absorption polarizer P1.

  The polarization separation film I is the polarization separation film of the present invention described above. In FIG. 3, the arrow written on the polarization separation film I represents the longitudinal direction of the groove portion of the polarization separation film I. The absorptive polarizer P1 is arranged so that the absorption axis is parallel to the longitudinal direction of the groove of the polarization separation film I. The absorption polarizer P2 is arranged so that the absorption axis is orthogonal to the absorption axis of the absorption polarizer P1.

  In such a liquid crystal display device, when the light emitted from the light source L through the diffusion plate D is incident on the polarization separation film I, the polarization separation film I reflects polarized light parallel to the longitudinal direction of the groove portion and extends in the longitudinal direction of the groove portion. Transmits orthogonally polarized light. Further, the polarized light reflected by the polarization separation film I is converted into non-polarized light by being multiple-reflected by the light diffusing plate D and the reflecting plate W, for example. The converted light is incident on the polarization separation film I again. At this time, as described above, the incident light reflects polarized light parallel to the longitudinal direction of the groove and transmits polarized light orthogonal to the longitudinal direction of the groove. For this reason, by repeating such polarization separation, the polarized light that can be transmitted through the absorptive polarizer P1 can be increased, and the light utilization efficiency can be enhanced.

  Hereinafter, the polarization separation film of the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

<Example 1>
After embossing the surface of a transparent, long thermoplastic resin film using a mold that has an uneven shape (a pattern opposite to the desired uneven shape) formed on the surface by cutting, the surface of this substrate absorbs light. A polarizing separation film was prepared by laminating an aluminum layer, which is a conductive thin film layer.

  Specifically, a focused ion beam processing apparatus is used on a 0.2 mm × 1 mm surface of a cuboid single crystal diamond of dimensions 0.2 mm × 1 mm × 1 mm brazed to an 8 mm × 8 mm × 60 mm SUS shank. Then, focused ion beam processing using an argon ion beam is performed, and a groove having a width of 50 nm and a depth of 60 nm parallel to a 1 mm long side is carved at a pitch of 130 nm, and a linear protrusion having a width of 80 nm and a height of 60 nm is pitched. A cutting tool formed at 130 nm was produced.

  Next, nickel-phosphorous electroless plating with a thickness of 100 μm was applied to the side surface of a roll made of stainless steel SUS430 with a diameter of 80 mm and a height of 125 mm, and nickel-phosphorus was applied using a precision micromachining machine and the above cutting tool. A linear protrusion having a parallel width of 50 nm, a height of 60 nm, and a pitch of 130 nm was cut on the electroless plating surface.

A thermoplastic resin film comprising a norbornene polymer (Japan) as a transparent and long resin film between the mold having a surface temperature of about 200 ° C. and a rubber roll having a surface temperature of about 60 ° C. Product name: ZEONOR film ^■ , light transmittance 92%, haze <0.1%, refractive index 1.53, thickness of about 60 μm) manufactured by Zeon Co., Ltd. while being continuously passed so as to be in contact with the rubber roll side. A plurality of substantially parallel groove portions having a width of 50 nm and a height of 60 nm were formed on the film surface at a pitch (interval of groove portions) of 130 nm.

  Next, an aluminum layer as a light-absorbing thin film layer was laminated with a thickness of 30 nm on the groove side surface of the substrate using a sputtering apparatus. As described above, a polarization separation film as shown in FIG. 4 was produced. Moreover, each dimension etc. of the produced polarization separation film are shown in Table 1.

  Using the spectrophotometer (manufactured by JASCO Corporation) arranged on the optical path in the order of the light source, the polarizing plate for making polarization, the polarizing separation film, and the photodetector with respect to the polarization separation film thus produced. The polarized light separation film was irradiated with polarized light having wavelengths of 430 nm, 530 nm, and 630 nm, and its performance was evaluated. Table 2 shows the complex refractive index and the like of the thin film layer at each measurement wavelength. Further, in this polarized light separating film, the transmittance of light that vibrates in the direction perpendicular to the longitudinal direction of the groove (polarized transmittance), which is the most easily polarized light, and the longitudinal direction of the groove, which is the most difficult polarized light. The transmittance of light oscillating in a direction parallel to is measured, and the contrast which is the ratio of these is obtained. Table 2 shows the results of polarization transmittance and contrast.

For the complex refractive index measurement of each part of the polarization separation film at each measurement wavelength, a flat film-like material is prepared separately using the same material and measured using a spectroscopic ellipsometer (manufactured by JA Woollam). Using.
Regarding the shape measurement of the polarized light separating film, a focused ion beam (FIB) was processed into a thin wall shape so that a section of a part of the polarized light separating film appeared, and the shape was measured with a transmission electron microscope (TEM). For 10 cycles, the shape of the groove and the aluminum film thickness were measured, and the average value was taken as the measured value.

<Example 2>
A polarization separation film as shown in FIG. 5 was produced in the same manner as in Example 1, and evaluated in the same manner. This polarized light separating film is different from the polarized light separating film of Example 1 in the shape of the groove, and the cross sectional shape of the groove is an inverted isosceles trapezoid. Table 3 shows the dimensions of such a polarized light separating film. The evaluation results are shown in Table 4.

  As shown in Examples 1 and 2, by satisfying the above conditions (1) to (5), the values of polarization transmittance and contrast are sufficiently large, and the points of polarization transmittance and contrast are excellent. I understand that.

It is a vertical sectional view showing a part of the polarization separation film according to the second embodiment of the present invention. It is a vertical sectional view showing a part of the polarization separation film according to the first embodiment of the present invention. It is a schematic diagram which shows a liquid crystal display device provided with the polarized light separation film of this invention. 1 is a view showing a polarized light separation film produced in Example 1. FIG. 6 is a view showing a polarized light separation film produced in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Arrow 11,12 Polarization separation film a Substrate b Absorbing thin film layer D Diffusion plate I Polarization separation film L Light source LC Liquid crystal cell P1, P2 Absorption type polarizer X, Y Groove W Reflector

Claims (7)

A step of pressing a roll-shaped mold in which a predetermined pattern is formed on a substrate including a transparent and long resin film to form a plurality of rows of grooves extending substantially parallel to each other on the surface of the substrate; ,
Forming a light-absorbing thin film layer on the surface of the substrate on which the groove portion is formed so as to cover the entire surface of the substrate including the groove portion when viewed from a position facing the substrate surface. The manufacturing method of the polarization separation film which satisfy | fills following (1)-(5).

(1) The light-absorbing thin film layer has a real part n ₁ of a complex refractive index at a wavelength λ ₀ of 2.5 or more or an imaginary part k ₁ of the complex refractive index of 1.5 or more.
(2) The value (h ₀ −h ₁ ) obtained by subtracting the thickness h ₁ of the light-absorbing thin film layer from the depth h _{0 of the} groove formed on the surface of the substrate is −0.1 × λ ₀ / (2π ² n ₁ ² k ₁ ) greater than ^1/2 .
(3) The average angle θ defined by the formula (A) is 60 to 90 °.

However, in the formula (A), z represents a distance in the height direction when the bottom surface of the groove is set to 0 (h ₀ is the top of the groove). θ (z) represents an angle on the groove side formed by a straight line corresponding to the side surface of the groove at height z and a straight line representing the substrate surface in the vertical sectional view of the polarization separation film.
(4) The interval d between the adjacent groove portions is smaller than λ ₀ / n ₀ . Where n ₀ is the real part of the complex refractive index of the resin film.
(5) The average width t of the groove is larger than 0.1d and smaller than 0.8d.
  The method for producing a polarized light separating film according to claim 1, wherein in the step of forming the light-absorbing thin film layer, the light-absorbing thin film layer is also formed on a side surface portion of the groove.   The process for forming a light-absorbing thin film layer, wherein the light-absorbing thin film layer is continuously formed across the surface of the substrate and the side surface portion of the groove part. Method.   The manufacturing method of the polarization separation film of any one of Claims 1-3 which further includes the process of forming a protective layer in the surface side of the said light-absorbing thin film layer after the process of forming a light-absorbing thin film layer.   The method for producing a polarized light separation film according to claim 1, wherein the light-absorbing thin film layer is made of aluminum.   The polarized light separation according to any one of claims 1 to 5, wherein the roll-shaped mold has a metal film formed on the surface thereof by plating of copper, nickel, a nickel-phosphorus alloy, or palladium. A method for producing a film.   A method of pressing a roll-shaped mold on which a predetermined pattern is formed against a substrate including a transparent and long resin film is provided between a roll-shaped mold on which a predetermined pattern is formed and a rubber roll. The method for producing a polarization-separating film according to claim 1, which is a method of pressing while sandwiching a transparent and long resin substrate.

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