JP6903470B2 - Optical retardation member and projector - Google Patents

Description

The present invention relates to an optical retardation member and a projector using the same.

Optical retardation plates have numerous uses, such as projectors (projection-type display devices), reflective liquid crystal display devices, semi-transmissive liquid crystal display devices, optical disk pickups, and PS conversion elements. Is used for.

The optical retardation plate shall be provided with one formed of naturally occurring birefringent crystals such as calcite, mica, and quartz, one formed of birefringent polymer, and artificially provided with a periodic structure shorter than the wavelength used. Some are formed by.

As an optical retardation plate formed by artificially providing a periodic structure, there is one having an uneven structure provided on a transparent substrate. The uneven structure used for the optical retardation plate has a period shorter than the wavelength used, and has, for example, a striped pattern as shown in FIG. Such a concavo-convex structure has refractive index anisotropy, and when light L is incident perpendicularly to the substrate 420 of the optical retardation plate 400 of FIG. 10, it is parallel to the periodic direction of the concavo-convex structure in the concavo-convex structure. Since the polarized light component and the polarized light component perpendicular to the periodic direction of the concave-convex structure propagate at different speeds, a phase difference occurs between the two polarized light components. This phase difference can be controlled by adjusting the height (depth) of the concave-convex structure, the refractive index difference between the material constituting the convex portion and the material (air) between the convex portions, and the like. The optical retardation plate used for the above-mentioned device such as a projector needs to generate a phase difference of λ / 4 or λ / 2 with respect to the wavelength λ used, but such a sufficient phase difference can be generated. In order to form a possible optical retardation plate, the difference between the refractive index of the material constituting the convex portion and the refractive index of the material (air) between the convex portions and the height (depth) of the concave-convex structure are sufficiently increased. There is a need. As such an optical retardation plate, Patent Document 1 proposes a plate having a concave-convex structure whose surface is coated with a high-refractive index material.

In Patent Document 2, in order to improve the transmittance of the optical retardation plate, it is possible to form a low refractive index film having a refractive index lower than that of the high refractive index film on the high refractive index film formed on the concave-convex structure. Are listed.

Special Fair 7-990402 Japanese Unexamined Patent Publication No. 2005-99099

In particular, when the optical retardation member is used for a projector or the like, it is desired that the optical retardation member has a high transmittance in a wide wavelength range. In the retardation plate disclosed in Patent Document 1, since the high refractive index layer is in contact with air, most of the light incident on the retardation plate is reflected at the interface between the high refractive index layer and air. The transmittance of the retardation plate is low. Further, in Patent Document 2, the transmittance of the optical retardation plate is improved by forming a low refractive index film having a refractive index lower than that of the high refractive index film on the high refractive index film formed on the uneven structure. However, there is a demand for further improving the transmittance of the optical retardation plate.

Further, the optical retardation plate described in Patent Document 2 does not have sufficient mechanical strength characteristics because the cross-sectional shape of the convex portion of the concave-convex structure is rectangular. Further, as described in Patent Document 2, the high-refractive index film and the low-refractive index film are laminated only on the upper surface of the convex portion and the bottom surface of the concave portion of the concave-convex structure to maintain the concave-convex structure (lattice pattern) of the substrate. The structure is difficult to form by a film forming method such as a general vapor deposition method or a sputtering method.

Therefore, an object of the present invention is an optical retardation member which can exhibit high transmittance in a wide wavelength range, can generate a desired phase difference, and can be formed by a normal film forming method and has high mechanical strength. And to provide a projector using the same.

According to the first aspect of the present invention, it is an optical retardation member that generates a phase difference in incident light.
A transparent substrate having a concavo-convex pattern composed of a plurality of convex portions extending in one direction and having a substantially trapezoidal cross section on a plane perpendicular to the extending direction.
A high-refractive index layer formed on the upper surface and the side surface of the convex portion of the transparent substrate and having a higher refractive index than the convex portion.
A laminate composed of 2n + 1 (n is a positive integer) layers formed on the high refractive index layer on the upper surface of the convex portion is provided.
An air layer exists between the high refractive index layers formed on the opposite side surfaces of the adjacent convex portions.
The laminate is formed on the first layer formed on the high refractive index layer, the second k layer formed on the second k-1 layer (k is an integer of 1 to n), and the second k layer. With the formed second k + 1 layer,
The refractive index of the first layer is lower than that of the high refractive index layer.
An optical retardation member having a refractive index of the second k + 1 layer lower than that of the second k layer is provided.

In the optical retardation member, the refractive index of the second k-1 layer (k is an integer of 1 to n) may be lower than the refractive index of the second k layer.

In the optical retardation member, the second k layer and the high refractive index layer may be made of the same material.

In the optical retardation member, the second k + 1 layer and the second k-1 layer may be made of the same material.

In the optical retardation member, n may be 1. In this case, the refractive index of the second layer may be in the range of 2.1 to 2.6, and the refractive index of the first layer and the third layer may be in the range of 1.3 to 1.55. ..

In the optical retardation member, the laminate may be formed on the high refractive index layer on the upper surface and the side surface of the convex portion of the transparent substrate.

The optical retardation member may have an average transmittance of 97% or more in the wavelength range of 430 nm to 680 nm.

In the optical retardation member, the material constituting the convex portion may be a sol-gel material.

According to the second aspect of the present invention, a projector including the optical retardation member of the first aspect is provided.

According to the third aspect of the present invention, a light generation mechanism for generating linearly polarized light and
An incident-side wave plate composed of the optical retardation member of the first aspect and converting the light emitted from the light generation mechanism into circularly polarized light.
An image display element that modulates the light converted to circularly polarized light,
An emission side wave plate composed of the optical retardation member of the first aspect and converting the light modulated by the image display element into linearly polarized light.
A projector including a projection optical system for projecting the light modulated by the image display element is provided.

According to the fourth aspect of the present invention, a light generation mechanism for generating linearly polarized light and
A wave plate composed of the optical retardation member of the first aspect and converting the light emitted from the light generation mechanism into circularly polarized light,
A diffusing element that diffuses the light converted to circularly polarized light,
An image display element that modulates the light diffused by the diffusion element, and
A projector including a projection optical system for projecting the light modulated by the image display element is provided.

Since the optical retardation member of the present invention uses a transparent substrate having a concavo-convex pattern composed of convex portions having a substantially trapezoidal cross-sectional shape, the mechanical strength is high. Further, since the high refractive index layer is formed on the side surface of the convex portion of the transparent substrate and the air layer exists between the high refractive index layers formed on the opposite side surfaces of the adjacent convex portions, the optical phase difference of the present invention is obtained. The desired phase difference can be given to the light transmitted through the member. Further, in the optical retardation member of the present invention, a laminated body composed of three or more odd layers is formed on a high refractive index layer formed on the upper surface of the convex portion of the transparent substrate, and each layer of the laminated body is formed. When the refractive index satisfies a predetermined magnitude relationship, it is possible to have a high transmittance in a wide wavelength range. Therefore, the optical retardation member of the present invention has characteristics suitable for various uses such as a projector.

1 (a) to 1 (f) are schematic views showing an example of the cross-sectional structure of the optical retardation member of the embodiment. It is a flowchart which shows the manufacturing method of the optical retardation member of embodiment. It is the schematic of the apparatus used for manufacturing the transparent substrate of an optical retardation member. It is a conceptual diagram which shows an example of the structure of the projector using the optical retardation member. It is a figure which shows the relative relationship of the optical axis of each component which constitutes the 1st image formation system of the projector using the optical retardation member. It is a conceptual diagram which shows another example of the structure of the projector using the optical retardation member. FIG. 7A shows a graph in which the maximum average transmittance of the optical retardation member obtained by simulation in Example 1 is plotted against the refractive index of the second layer, and FIG. 7B shows Example 2. The graph which plotted the maximum average transmittance of the optical retardation member obtained by the simulation with respect to the refractive index of the 1st layer and the 3rd layer is shown. FIG. 8 is a table showing the thickness and refractive index of each layer of the optical retardation members of Examples 3 to 15 and Comparative Examples 1 to 5 and the evaluation results of the optical characteristics obtained by simulation. FIG. 9 shows the transmission spectra of the optical retardation members of Examples 3 and 4 and Comparative Examples 1 to 4 obtained by simulation. It is a figure which conceptually shows an example of the optical retardation member of the prior art.

Hereinafter, the optical retardation member of the present invention, a method for manufacturing the same, and a projector using the same will be described with reference to the drawings.

[Optical retardation member]
As shown in FIG. 1A, the optical retardation member 100 of the embodiment has a transparent substrate 40 having a concavo-convex pattern 80 composed of convex portions 60 having a substantially trapezoidal cross section, and an upper surface 60t of the convex portions 60. The high-refractive index layer 30 formed on the side surface 60s and the laminated body 20 formed on the high-refractive index layer 30 on the upper surface 60t of the convex portion 60 are provided. An air layer 90 exists between the high refractive index layers 30 formed on the opposite side surfaces 60s of the adjacent convex portions 60.

<Transparent substrate>
In the optical retardation member 100 of the embodiment shown in FIG. 1A, the transparent substrate 40 is composed of a flat substrate 42 and a concave-convex structure layer 50.

The base material 42 is not particularly limited, and a known base material that transmits visible light can be appropriately used. For example, a base material made of a transparent inorganic material such as glass; polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, etc.), acrylic resin (polymethylmethacrylate, etc.), polycarbonate, polyvinyl chloride, styrene resin. A base material made of a resin such as (ABS resin or the like), a cellulose-based resin (triacetyl cellulose or the like), a polyimide-based resin (polyimide resin, polyimideamide resin or the like), a cycloolefin polymer or the like can be used. When the optical retardation member 100 is used in a projector, the optical retardation member 100 is required to have high light resistance and high heat resistance. Therefore, it is desirable that the base material 42 is a base material having high light resistance and heat resistance. .. In this respect, a base material made of an inorganic material is preferable. A surface treatment or an easy-adhesion layer may be provided on the base material 42 in order to improve the adhesion. Further, a smoothing layer may be provided to fill the protrusions on the surface of the base material 42. The thickness of the base material 42 is preferably in the range of 1 μm to 20 mm. An antireflection layer 44 (see FIG. 1 (f)) may be provided on the surface of the base material 42 opposite to the surface on which the uneven structure layer 50 is formed in order to improve the transmittance. The antireflection layer 44 may be composed of a single layer or a plurality of layers, or may have a sub-wavelength microstructure having an antireflection effect. Further, when another optical member is bonded (bonded) to the surface opposite to the surface on which the concave-convex structure layer 50 of the base material 40 is formed, the reflection at the interface between the other optical member and the base material 40 becomes small. As described above, the base material 40 and another optical member may be bonded with an adhesive, a pressure-sensitive adhesive, a refracting liquid or the like having an appropriate refractive index.

The concavo-convex structure layer 50 has a plurality of convex portions 60 and recesses 70, whereby the surface of the concavo-convex structure layer 50 defines the concavo-convex pattern 80. The concave-convex structure layer 50 is preferably made of a material having a refractive index at a wavelength of 550 nm (hereinafter, appropriately referred to as “refractive index”) in the range of 1.2 to 1.8. Examples of the material constituting the concave-convex structure layer 50 include Si-based materials such as silica, SiN, and SiON _{, Ti-based materials such as TiO 2} , ITO (indium-tin-oxide) -based materials, ZnO, ZnS, and the like. Inorganic materials such as ZrO ₂ , Al ₂ O ₃ , BaTIO ₃ , Cu ₂ O, MgS, AgBr, CuBr, BaO, Nb ₂ O ₅ , and SrTiO _{2 can be used.} These inorganic materials may be materials formed by a sol-gel method or the like (sol-gel material). In addition to the above inorganic materials, polyethylene, polypropylene, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyvinyl chloride, polystyrene, AS resin, acrylic resin, polyamide, polyacetal, polybutylene terephthalate, glass-reinforced polyethylene terephthalate, polycarbonate, modified polyphenylene ether. , Polyphenylene sulfide, polyether ether ketone, fluororesin, polyarylate, polysulfone, polyethersulfone, polyamideimide, polyetherimide, thermoplastic polyimide, and other thermoplastic resins; phenolic resin, melamine resin, urea resin, epoxy resin, non-existent Thermoplastic resins such as saturated polyester resin, alkyd resin, silicone resin, diallyl phthalate resin; UV curable (meth) acrylate resin, UV curable acrylic urethane resin, UV curable polyester acrylate resin, UV curable epoxy An ultraviolet curable resin such as an acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin; a resin material such as a material obtained by blending two or more of these can also be used. Further, a material in which the above-mentioned inorganic material is composited with the above-mentioned resin material may be used. Further, both the inorganic material and the resin material may contain known fine particles and fillers in order to obtain hard coat properties and the like. Further, a material containing an ultraviolet absorbing material in the above material may be used. The ultraviolet absorbing material has an effect of suppressing deterioration of the concave-convex structure layer 50 by absorbing ultraviolet rays and converting light energy into a harmless form such as heat. As the ultraviolet absorber, conventionally known ones can be used, and for example, a benzotriazole-based absorbent, a triazine-based absorbent, a salicylic acid derivative-based absorbent, a benzophenone-based absorbent, and the like can be used. When the optical retardation member 100 is used in a projector, it is desirable that the concave-convex structure layer 50 has high light resistance and heat resistance. In this respect, the concave-convex structure layer 50 is preferably made of an inorganic material.

Each convex portion 60 of the concave-convex structure layer 50 extends in the Y direction (depth direction) of FIG. 1A, and the plurality of convex portions 60 generate a phase difference due to the design wavelength (optical retardation member 100). It is arranged in a period shorter than the wavelength of the light to be made. The cross section in the ZX plane orthogonal to the extending direction of each convex portion 60 is substantially trapezoidal. In the present application, the "substantially trapezoidal shape" has a set of opposite sides substantially parallel to the surface of the base material 42, and the side (lower bottom) of the opposite sides close to the surface of the base material 42 is the other side (upper bottom). ), Which means a substantially quadrangle in which the angle between the lower base and the two hypotenuses is an acute angle. Each side of the substantially quadrangle may be curved. That is, each convex portion 60 has a width (length in a direction perpendicular to the extending direction of the convex portion 60) upward from the surface of the base material 42 (direction away from the surface of the base material 42), that is, FIG. 1 (a). ) In the x direction) should be small. Moreover, each vertex may be rounded. Further, the length of the upper base may be 0. That is, in the present application, "substantially trapezoidal shape" is a concept including "substantially triangular shape". The length of the upper base is preferably larger than 0. A convex portion having a substantially trapezoidal cross section having an upper base larger than 0 has the following advantages as compared with a convex portion having a substantially triangular cross section. That is, it is easy to form a mold used for forming the convex portion by the imprint method, and the mechanical strength such as the surface pressing resistance of the convex portion is high.

The height of the convex portion 60 (unevenness height) is preferably in the range of 100 to 2000 nm. If the height of the convex portion 60 is less than 100 nm, it becomes difficult to generate a desired phase difference when visible light is incident on the optical phase difference member 100. When the height of the convex portion 60 exceeds 2000 nm, the aspect ratio of the convex portion 60 (the ratio of the convex portion height to the convex portion width) is large, so that it becomes difficult to form the concave-convex pattern. The width of the upper surface 60t of the convex portion 60 (the length of the upper base of the substantially trapezoidal cross section on the surface orthogonal to the extending direction of the convex portion 60) is preferably 50 nm or less. When the width of the upper surface 60t of the convex portion 60 is 50 nm or less, it becomes easy to increase the transmittance of the optical retardation member 100. The uneven pitch of the uneven pattern 80 is preferably in the range of 50 to 1000 nm. Concavo-convex patterns with a pitch of less than 50 nm are difficult to form by the nanoimprint method. When the pitch exceeds 1000 nm, it becomes difficult to secure sufficient colorless transparency as an optical retardation member.

In the optical retardation member 100 shown in FIG. 1 (a), adjacent convex portions 60 are in contact with each other on the bottom surface (or the hem of the convex portion 60) of the convex portions 60, which is shown in FIG. 1 (b). Like the optical retardation member 100a, the bottom surfaces of adjacent convex portions 60a (or the hem of adjacent convex portions 60a) may be separated from each other by a predetermined distance. In this case, a part of the light passing through the optical retardation member 100a is reflected at the interface between the recess 70a and the high refractive index layer 30a formed on the recess 70a, so that the optics as shown in FIG. 1 (b) are reflected. The retardation member 100a tends to have a lower transmittance than the optical retardation member 100 as shown in FIG. 1A. Therefore, from the viewpoint of increasing the transmittance of the optical retardation member 100a, the distance between the bottom surfaces of the adjacent convex portions 60a, that is, the region (recessed portion) sandwiched between the adjacent convex portions 60a on the surface of the concave-convex structure layer 50a. The width of 70a is preferably smaller, and particularly preferably within the range of 0 to 0.2 times the pitch of the uneven pattern. In other words, the width of the bottom surface of the convex portion 60a is preferably in the range of 0.8 to 1 times the pitch of the uneven pattern. The ratio of the width of the concave portion 70a to the pitch of the concave-convex pattern is 0.2 or less, that is, the ratio of the width of the bottom surface of the convex portion 60a to the pitch of the concave-convex pattern is 0.8 or more, so that the optical retardation member 100 is transparent. It becomes easier to increase the rate.

<High refractive index layer>
The high refractive index layer 30 is a layer having a higher refractive index than the concave-convex structure layer 50 of the transparent substrate 40. The high refractive index layer 30 is preferably made of a material having a refractive index of 2.3 or more. Examples of the material constituting the high refractive index layer 30 include metals such as Ti, In, Zr, Ta, Nb, and Zn, and inorganic substances such as oxides, nitrides, sulfides, oxynitrides, and halides of those metals. Materials can be used.

The high refractive index layer 30 covers the convex portion 60. That is, the high refractive index layer 30 covers the upper surface 60t and the side surface 60s of the convex portion 60. Since the convex portion 60 is covered with the high refractive index layer 30, the phase difference caused by the periodic arrangement of the convex portion 60 and the air layer 90 described later becomes large. Therefore, the height of the convex portion 60 can be reduced, that is, the aspect ratio of the convex portion 60 can be reduced, so that the uneven pattern 80 can be easily formed. The thickness _{T ht} of the high refractive index layer 30 formed on the upper surface 60t of the convex portion 60 is preferably in the range of 50 to 250 nm.

The thickness T _hs of the high refractive index layer 30 formed on the side surface 60s of the projecting portion 60, when used for the purpose of providing a phase difference of the optical phase difference members 100 to light of a particular wavelength lambda, 0.03Ramuda～ It is preferably 0.11λ. For example, when using the optical retardation member 100 for the purpose of providing a phase difference of wavelength 470nm light, the thickness _{T hs} of the high refractive index layer 30 on the side 60s of the projecting portion 60 that is within the 15~50nm preferable. _{When the thickness Ths} of the high refractive index layer 30 is within the above range, it is possible to secure the phase difference required for the λ / 4 retardation plate while having high transmittance. The "thickness T _hs of the high refractive index layer 30 on the side 60s of the projecting portion 60" in the present application, and the height from the bottom surface of the projecting portion 60 to the top of the stack 20 to be described later is H, convex It means the thickness of the high refractive index layer 30 at a position at a height of H / 2 from the bottom surface of the portion 60.

<Laminated body>
The laminate 20 is composed of 2n + 1 layers (n is a positive integer), that is, 3 or more odd-numbered layers. The laminated body 20 is formed on the high refractive index layer 30 on the upper surface 60t of the convex portion 60. In the optical retardation member 100 shown in FIG. 1A, the laminated body 20 is composed of three layers, a first layer 22, a second layer 24, and a third layer 26. The first layer 22 is formed directly on the high refractive index layer 30, the second layer 24 is formed directly on the first layer, and the third layer 26 is formed directly on the second layer 24.

The refractive index of the first layer 22 is lower than that of the high refractive index layer 30, and the refractive index of the third layer 26 is lower than that of the second layer 24. Thereby, as shown in Examples described later, the optical retardation member 100 can have a high transmittance in a wide wavelength range.

The refractive index of the second layer 24 may be higher than that of the first layer 22, or the refractive index of the second layer 24 may be lower than that of the first layer 22.

When the refractive index of the second layer 24 is higher than the refractive index of the first layer 22, layers having a relatively high refractive index and layers having a relatively low refractive index are alternately laminated in the laminated body 20. Has a structure. In this case, the refractive index of the first layer 22 and the third layer 26 may be in the range of 1.3 to 1.55. When the refractive index of the first layer 22 or the third layer 26 exceeds 1.55, as shown in Examples described later, the average transmittance of the optical retardation member 100 (the average transmittance of light at a wavelength of 430 nm to 680 nm). ) Tends to be low. Materials with a refractive index of less than 1.3 tend to be less stable. The refractive index of the second layer 24 may be 2.1 or more, preferably in the range of 2.1 to 2.6. When the refractive index of the second layer 24 is less than 2.1, the average transmittance of the optical retardation member 100 tends to be low, as shown in Examples described later. A material having a refractive index of more than 2.6 tends to have low transparency in the visible light region of the material itself. Further, the first layer 22 and the third layer 26 may be formed of the same material, and the second layer 24 may be formed of the same material as the high refractive index layer 30. As a result, the optical retardation member 100 can be manufactured with a small number of materials, so that the manufacturing cost can be reduced.

When the refractive index of the second layer 24 is lower than that of the first layer 22, the layer farther from the high refractive index layer 30 has a lower refractive index in the laminated body 20. In this case, the refractive index of the third layer 26, which is the outermost layer (top layer) of the laminated body 20, may be in the range of 1.3 to 1.4.

Examples of the material constituting the first layer 22 and the third layer 26 include oxides and fluorides of Si, Al, Li, Mg, Ca, K such as _{SiO 2} , MgF _2. Examples of the material constituting the second layer 24 include metals such as Ti, In, Zr, Ta, Nb, and Zn, and inorganic materials such as oxides, nitrides, sulfides, oxynitrides, and halides of these metals. Can be mentioned.

_{The thickness T st1} of the first layer 22 formed on the high refractive index layer 30 on the upper surface 60t of the convex portion 60 _{may be in the range of 20 to 40 nm, and the thickness T st2} of the second layer 24 on it may be in the range of 20 to 40 nm. May be in the range of 35 to 55 nm, and the thickness T _st3 of the third layer 26 above it may be in the range of 100 to 140 nm, and the first layer 22, the second layer 24, and the third layer 26 may be in the range. _{The thickness T st} of the laminated body 20, which is the total thickness of the above, may be in the range of 155 to 210 nm. In this case, the average transmittance of the optical retardation member 100 tends to be high. Further, the thickness T _st1 of the first layer 22 may be in the range of 25 to 35 nm, the thickness T _st2 of the second layer 24 may be in the range of 35 to 45 nm, and the thickness T _{st 3 of the third layer 26 may be in the range.} May be in the range of 115 to 125 nm, and the thickness T _st of the laminate 20 may be in the range of 185 to 195 nm. In this case, the average transmittance of the optical retardation member 100 tends to be higher.

The laminated body 20b may also be formed on the high refractive index layer 30b on the side surface 60bs of the convex portion 60b, as in the optical retardation member 100b shown in FIG. 1C. The thickness of the laminated body 20b formed on the high refractive index layer 30b on the side surface 60bs of the convex portion 60b (thickness of the laminated body 20b on the side surface 60bs of the convex portion 60b) T _ss is preferably small and is in the range of 5 to 40 nm. It is preferably inside. When the thickness T _ss of the laminated body 20b is within the above range, the transmittance of the optical retardation member 100b can be increased while suppressing the reduction of the phase difference due to the film formation of the laminated body 20b on the side surface 60bs. Further, when the refractive index of the second layer 24b is increased, the second layer 24b formed on the side surface also causes a phase difference due to structural birefringence, so that the phase difference is reduced due to the laminated body 20b being formed on the side surface. It can be suppressed. _{In the present application, the "thickness T ss} of the laminated body 20b on the side surface 60bs of the convex portion 60b" means that the height from the bottom surface of the convex portion 60b to the top of the laminated body 20b is Hb, from the bottom surface of the convex portion 60. It means the thickness of the laminated body 20b at the height position of Hb / 2.

When the laminate consists of an odd number of layers of 5 or more, that is, when the number of layers of the laminate is 2n + 1 (n is an integer of 2 or more), the laminate is formed directly on the high refractive index layer. The first layer, the second k layer directly formed on the second k-1 layer (k is an integer of 1 to n), and the second k + 1 layer directly formed on the second k layer are provided, and the most of the laminated body. The surface layer is the second n + 1 layer. The refractive index of the first layer is lower than that of the high refractive index layer, and the refractive index of the second k + 1 layer is lower than that of the second k layer. Thereby, the optical retardation member of the embodiment can have high transmittance in a wide wavelength range. The refractive index of the second k-1 layer may be higher than the refractive index of the second k-1 layer, or the refractive index of the second k layer may be lower than the refractive index of the second k-1 layer. When the refractive index of the second k layer is higher than the refractive index of the second k-1 layer, the laminate has a relatively low refractive index with a layer having a relatively high refractive index with respect to the layer in contact with the layer. It has a structure in which layers are alternately laminated. In this case, the second k-1 layer and the second k + 1 layer may be formed of the same material, and the second k layer may be formed of the same material as the high refractive index layer. As a result, the optical retardation member can be manufactured with a small number of materials, so that the manufacturing cost can be reduced.

<Air layer>
The air layer 90 exists in the space (gap) between the high refractive index layers 30 formed on the opposite side surfaces 60s of the adjacent convex portions 60. In the optical retardation member 100, the high refractive index layer 30 covering the air layer 90 and the convex portion 60 is periodically arranged to cause a phase difference in the light transmitted through the optical retardation member 100. it can. The width W of the air layer 90 is preferably in the range of 35 to 100 nm. When the width W of the air layer 90 is within the above range, a large phase difference can be secured even at a low uneven height. Such an optical retardation member 100 can be suitably used as a 1/4 wave plate. In the present application, the "width W of the air layer 90" is a position of H / 2 from the bottom surface of the convex portion 60, where H is the height from the bottom surface of the convex portion 60 to the uppermost portion of the laminated body 20. It means the thickness of the air layer 90 in the above (distance between the surfaces of the high refractive index layer 30 formed on the opposite side surfaces 60s of the adjacent convex portions 60).

The optical retardation member 100 shown in FIG. 1 (a) includes a transparent substrate 40 in which the concave-convex structure layer 50 is formed on the base material 42, but instead, the optical shown in FIG. 1 (d) is used. A transparent substrate 40c in which a plurality of structures forming convex portions 60c are formed on the substrate 42c, such as the retardation member 100c, may be provided. As shown in FIG. 1D, the bottom surfaces of adjacent convex portions 60c (or the hem of the convex portions 60c) may be in contact with each other, or the bottom surfaces of adjacent convex portions 60c are separated from each other by a predetermined distance. It may be provided and the surface of the base material 42c may be exposed. As the base material 42c, the same base material as the base material 42 of the optical retardation member 100 shown in FIG. 1A can be used. The convex portion 60c may be made of the same material as the material constituting the concave-convex structure layer 50 of the optical retardation member 100 shown in FIG. 1A.

Further, as in the optical retardation member 100d shown in FIG. 1 (e), the transparent substrate 40d is composed of a substrate shaped so that the surface of the substrate itself constitutes an uneven pattern 80d composed of convex portions 60d. You may be. In this case, the transparent substrate 40d can be manufactured by molding the substrate so as to have the uneven pattern 80d as shown in FIG. 1 (e).

[Manufacturing method of optical retardation member]
A method for manufacturing the above-mentioned optical retardation member will be described. As shown in FIG. 2, the method for manufacturing the optical retardation member is mainly a step S1 for forming a transparent substrate having a concavo-convex pattern, a step S2 for forming a high refractive index layer, and a step S3 for forming a laminate. And have. The step S1 for forming the transparent substrate is a solution preparation step of preparing a precursor solution of an inorganic material, a coating step of applying the prepared precursor solution to the substrate, and a coating film of the precursor solution applied to the substrate. A drying step of drying, a pressing step of pressing a mold having a transfer pattern formed on the coating film, a temporary firing step of temporarily firing the coating film on which the mold is pressed, a peeling step of peeling the mold from the coating film, and curing of the coating film. It has a curing step to make it. The pressing step, the temporary firing step, and the peeling step are collectively referred to as a transfer step. Hereinafter, each step will be described in order.

<Solution adjustment process>
First, a solution of the precursor of the inorganic material is prepared. When forming a concavo-convex structural layer made of an inorganic material by using the sol-gel method, a metal alkoxide is prepared as a precursor of the inorganic material. For example, when forming a concavo-convex structural layer made of silica, tetramethoxysilane (TMS), tetraethoxysilane (TEOS), tetra-i-propoxysilane, tetra-n-propoxysilane, and tetra- are used as silica precursors. Tetraalkoxide monomers typified by tetraalkoxysilanes such as i-butoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, and tetra-t-butoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, and propyl. Trimethoxysilane, isopropyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane (METES), ethyltriethoxysilane, propyltriethoxysilane, isopropyltriethoxysilane, phenyltriethoxysilane, methyltripropoxysilane, ethyltripropoxy Silane, propyltriisopropoxysilane, isopropyltripropoxysilane, phenyltripropoxysilane, methyltriisopropoxysilane, ethyltriisopropoxysilane, propyltriisopropoxysilane, isopropyltriisopropoxysilane, phenyltriisopropoxysilane, triltriethoxy Trialkoxide monomers typified by trialkoxysilanes such as silane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldiisopropoxysilane, dimethyldi-n-butoxysilane, dimethyldi-i-butoxysilane, dimethyldi- sec-butoxysilane, dimethyldi-t-butoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldiisopropoxysilane, diethyldi-n-butoxysilane, diethyldi-i-butoxysilane, diethyldi-sec- Butoxysilane, diethyldi-t-butoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dipropyldipropoxysilane, dipropyldiisopropoxysilane, dipropyldi-n-butoxysilane, dipropyldi-i-butoxysilane, dipropyldi- sec-butoxysilane, dipropyldi-t-butoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, diisopropyldipropoxysilane, diisopropyldiisopropoxysilane, diisopropyldi-n-butoxysilane , Diisopropyldi-i-butoxysilane, diisopropyldi-sec-butoxysilane, diisopropyldi-t-butoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldipropoxysilane, diphenyldiisopropoxysilane, diphenyldi-n- Dialkoxide monomers typified by dialkoxysilanes such as butoxysilane, diphenyldi-i-butoxysilane, diphenyldi-sec-butoxysilane, and diphenyldi-t-butoxysilane can be used. Further, alkyltrialkoxysilanes and dialkyldialkoxysilanes having an alkyl group having C4 to C18 carbon atoms can also be used. Monomers having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxy Monopoly having an epoxy group such as silane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, monomer having a styryl group such as p-styryltrimethoxysilane, 3-methacryloxypropylmethyl Monomer having a methacryl group such as dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, acrylic group such as 3-acryloxypropyltrimethoxysilane N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyl 3-Ureidopropyltriethoxysilane, a monomer having an amino group such as triethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane Propyl groups such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane and other mercapto groups, bis (triethoxysilylpropyl) tetrasulfide and other sulfide groups, 3- Metal alkoxides such as a monomer having an isocyanate group such as isocyanate propyltriethoxysilane, a polymer obtained by polymerizing a small amount of these monomers, and a composite material characterized by introducing a functional group or a polymer into a part of the material may be used. .. Further, a part or all of the alkyl group and the phenyl group of these compounds may be substituted with fluorine. Further, examples thereof include, but are not limited to, metal acetylacetonate, metal carboxylate, oxychloride, chloride, and mixtures thereof. Examples of the metal species include, but are not limited to, Ti, Sn, Al, Zn, Zr, In, and the like, and mixtures thereof, in addition to Si. It is also possible to use a mixture of the precursors of the metal oxide as appropriate. Further, a mesoporous concavo-convex structure layer may be formed by adding a surfactant to these materials. Further, as a precursor of silica, a silane coupling agent having a hydrolyzing group having affinity and reactivity with silica and an organic functional group having water repellency in the molecule can be used. For example, silane monomers such as n-octyltriethoxylane, methyltriethoxysilane, and methyltrimethoxysilane, vinylsilanes such as vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, and vinylmethyldimethoxysilane, Methacrylic silanes such as 3-methacryloxypropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glyceride Epoxysilanes such as sidoxypropyltriethoxysilane, mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, sulfasilanes such as 3-octanoylthio-1-propyltriethoxysilane, 3-aminopropyl Triethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- (N) -Phenyl) Aminosilanes such as aminopropyltrimethoxysilane, polymers obtained by polymerizing these monomers, and the like can be mentioned.

When a mixture of TEOS and MTES is used as a precursor of the inorganic material, their mixing ratio can be, for example, 1: 1 in molar ratio. This precursor produces amorphous silica by subjecting it to hydrolysis and polycondensation reactions. In order to adjust the pH of the solution as a synthetic condition, an acid such as hydrochloric acid or an alkali such as ammonia is added. The pH is preferably 4 or less or 10 or more. Water may also be added to carry out hydrolysis. The amount of water added can be 1.5 times or more in molar ratio with respect to the metal alkoxide species.

Examples of the solvent for the precursor solution include alcohols such as methanol, ethanol, isopropyl alcohol (IPA) and butanol, aliphatic hydrocarbons such as hexane, heptane, octane, decane and cyclohexane, benzene, toluene, xylene and mesityrene. Aromatic hydrocarbons, ethers such as diethyl ether, tetrahydrofuran, dioxane, ketones such as acetone, methyl ethyl ketone, isophorone, cyclohexanone, butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol, benzyloxyethanol and the like. Ether alcohols, glycols such as ethylene glycol and propylene glycol, glycol ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and propylene glycol monomethyl ether acetate, esters such as ethyl acetate, ethyl lactate and γ-butyrolactone, phenol and chlorophenol. Phenols such as N, N-dimethylformamide, N, N-dimethylacetamide, amides such as N-methylpyrrolidone, halogen-based solvents such as chloroform, methylene chloride, tetrachloroethane, monochlorobenzene, dichlorobenzene, carbon disulfide Etc., hetero-element compounds such as water, water, and a mixed solvent thereof. In particular, ethanol and isopropyl alcohol are preferable, and water mixed with them is also preferable.

Additives for the precursor solution include polyethylene glycol, polyethylene oxide, hydroxypropyl cellulose, polyvinyl alcohol for adjusting viscosity, alkanolamines such as triethanolamine as a solution stabilizer, β-diketone such as acetylacetone, and β-ketoester. Formamide, dimethylformamide, dioxane and the like can be used. Further, as an additive of the precursor solution, a material that generates an acid or an alkali by irradiating light such as an energy ray typified by ultraviolet rays such as excimer UV light can be used. By adding such a material, the precursor solution can be cured (gelled) by irradiating with light to form an inorganic material.

Moreover, polysilazane may be used as a precursor of an inorganic material. Polysilazane is oxidized by heating or irradiation with energy rays such as excimer to form ceramics (silica modification) to form silica, SiN or SiON. Note that the "polysilazane", silicon - a polymer with a nitrogen bonds, Si-N, Si-H , SiO 2 consisting of N-H or the like, _Si 3 _{N 4} and both of the intermediate solid solution _SiO X _{N Y} such ceramic It is a precursor inorganic polymer. A compound that is ceramicized at a relatively low temperature and modified to silica or the like as represented by the following general formula (1) described in JP-A-8-11279 is more preferable.

General formula (1):
-Si (R1) (R2) -N (R3)-
In the formula, R1, R2, and R3 represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylsilyl group, an alkylamino group, or an alkoxy group, respectively.

Among the compounds represented by the general formula (1), perhydropolysilazane (also referred to as PHPS) in which all of R1, R2 and R3 are hydrogen atoms, and the hydrogen moiety bonded to Si is partially an alkyl group or the like. Substituted organopolysilazane is particularly preferred.

As another example of polysilazane that is ceramicized at low temperature, silicon alkoxide-added polysilazane obtained by reacting polysilazane with silicon alkoxide (for example, Japanese Patent Application Laid-Open No. 5-238827) and glycidol-added polysilazane obtained by reacting glycidol (Japanese Patent Laid-Open No. 5-238827). For example, JP-A-6-122852), alcohol-added polysilazane obtained by reacting alcohol (for example, JP-A-6-240208), and metal carboxylate-added polysilazane obtained by reacting metal carboxylate (Japanese Patent Laid-Open No. 6-240208). For example, JP-A-6-299118), acetylacetonate complex-added polysilazane obtained by reacting an acetylacetonate complex containing a metal (for example, JP-A-6-306329), and obtained by adding metal fine particles. Polysilazane to which metal fine particles are added (for example, Japanese Patent Application Laid-Open No. 7-196986) and the like can also be used.

As the solvent for the polysilazane solution, hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons, and ethers such as halogenated hydrocarbon solvents, aliphatic ethers and alicyclic ethers can be used. Amine or metal catalyst may be added to facilitate modification to the silicon oxide compound.

When polysilazane is used as the precursor of the inorganic material, the precursor solution may be cured by heating or irradiation with energy rays such as excimer to form the inorganic material.

<Applying process>
The precursor solution of the inorganic material prepared as described above is applied onto the substrate. A surface treatment or an easy-adhesion layer may be provided on the base material in order to improve the adhesion. As a method for applying the precursor solution, any application method such as a bar coating method, a spin coating method, a spray coating method, a dip coating method, a die coating method, or an inkjet method can be used, but a relatively large area substrate can be used. The bar coating method, the die coating method and the spin coating method are preferable because the precursor solution can be uniformly applied to the surface and the application can be completed quickly before the precursor solution is cured.

<Drying process>
After coating the precursor solution, the substrate may be held in the air or under reduced pressure to evaporate the solvent in the coating (precursor film). From the viewpoint of stability of uneven pattern formation, it is desirable that the drying time range in which pattern transfer can be performed is sufficiently wide, which includes drying temperature (holding temperature), drying pressure, precursor material type, and precursor material type. It can be adjusted by the mixing ratio, the amount of solvent used when preparing the precursor solution (precursor concentration), and the like. Since the solvent in the coating film evaporates just by holding the base material as it is, it is not always necessary to perform an active drying operation such as heating or blowing air, and the base material on which the coating film is formed is left as it is for a predetermined time. Or just transport within a predetermined time to perform subsequent steps.

<Pressing process>
Next, the concave-convex structure layer is formed by transferring the concave-convex pattern of the mold to the coating film using a mold for transferring the concave-convex pattern. As the mold, a film-like mold or a metal mold that can be manufactured by a method described later can be used, but it is desirable to use a flexible or flexible film-like mold. When a film-like mold is used, the mold may be pressed against the precursor film using a pressing roll. In the roll process using a pressing roll, the contact time between the mold and the coating film is shorter than that of the press type, so the pattern collapse due to the difference in the coefficient of thermal expansion of the mold, the base material, and the stage on which the base material is placed is prevented. It can be prevented, gas bubbles can be prevented from being generated in the pattern due to the sudden boiling of the solvent in the precursor membrane, and gas marks can be prevented from remaining. In addition, it has the advantages that the peeling force can be reduced, it is easy to cope with a large area, and air bubbles are not caught when pressed. Alternatively, the base material may be heated while pressing the mold. As an example of pressing the mold against the precursor film using the pressing roll, the film-like mold 140 is fed between the pressing roll 122 and the base material 42 conveyed directly under the pressing roll 122 as shown in FIG. The uneven pattern of 140 can be transferred to the coating film (precursor film) 64 on the base material 42. That is, when the film-shaped mold 142 is pressed against the coating film 64 by the pressing roll 122, the surface of the coating film 64 on the base material 42 is conveyed in synchronization with the film-shaped mold 140 and the base material 42. Cover with. At this time, by rotating the pressing roll 122 while pressing it against the back surface of the film-shaped mold 140 (the surface opposite to the surface on which the uneven pattern is formed), the film-shaped mold 140 and the base material 42 come into close contact with each other while advancing. In order to feed the long film mold 140 toward the pressing roll 122, it is convenient to use the film mold 140 as it is drawn out from the film roll around which the long film mold 140 is wound.

<Temporary firing process>
After pressing the mold against the precursor film, the precursor film may be calcined. By tentative firing, the precursor is converted into an inorganic material, the coating film is hardened, the uneven pattern is solidified, and it is difficult to collapse during peeling. When performing calcination, it is preferable to heat in the air at a temperature of room temperature to 300 ° C. It is not always necessary to perform temporary firing. Further, when a material that generates an acid or an alkali is added to the precursor solution by irradiating it with light such as ultraviolet light, instead of temporarily firing the precursor film, it is represented by ultraviolet light such as Exima UV light. The coating film may be cured by irradiating with energy rays.

<Peeling process>
After pressing the mold or pre-baking the precursor film, the mold is peeled off from the coating film (the precursor film or the inorganic material film formed by converting the precursor film). A known peeling method can be adopted as the mold peeling method. Since the convex portions and concave portions of the concave-convex pattern of the mold are arranged so as to extend in a uniform direction, the releasability is good. The peeling direction of the mold may be a direction parallel to the extending direction of the convex portion and the concave portion. Thereby, the releasability of the mold can be further improved. The mold may be peeled off while heating the coating film, whereby the gas generated from the coating film can be released and bubbles can be prevented from being generated in the coating film. When the roll process is used, the peeling force may be smaller than that of the plate-shaped mold used in the press type, and the mold can be easily peeled from the coating film without the coating film remaining on the mold. In particular, since the coating film is pressed while being heated, the reaction easily proceeds, and the mold is easily peeled off from the coating film immediately after pressing. Further, a peeling roll may be used to improve the peelability of the mold. As shown in FIG. 3, the peeling roll 123 is provided on the downstream side of the pressing roll 122, and the film-shaped mold 140 is rotationally supported while being urged to the coating film 64 by the peeling roll 123, whereby the film-shaped mold 140 becomes the coating film 64. The state of being attached to the film can be maintained by the distance between the pressing roll 122 and the peeling roll 123 (for a certain period of time). Then, by changing the course of the film-shaped mold 140 so as to pull the film-shaped mold 140 above the peeling roll 123 on the downstream side of the peeling roll 123, the film-shaped mold 140 has a coating film (concavo-convexness) on which the uneven pattern 80 is formed. It is peeled off from the structural layer) 50. The above-mentioned temporary firing or heating of the coating film 64 may be performed while the film-shaped mold 140 is attached to the coating film 64. When the peeling roll 123 is used, the peeling of the mold 140 can be further facilitated by peeling while heating at room temperature to 300 ° C., for example.

<Curing process>
After peeling the mold from the coating film (concavo-convex structure layer), the concavo-convex structure layer may be main-cured. The concave-convex structure layer can be main-cured by the main firing. When a precursor that is converted to silica by the sol-gel method is used, the hydroxyl groups and the like contained in the silica (amorphous silica) constituting the concave-convex structure layer are desorbed by the main firing, and the uneven structure layer becomes stronger. This firing is preferably carried out at a temperature of 200 to 1200 ° C. for about 5 minutes to 6 hours. At this time, when the concave-convex structure layer is made of silica, it becomes amorphous or crystalline, or a mixed state of amorphous and crystalline, depending on the firing temperature and firing time. The curing step does not necessarily have to be performed. Further, when a material that generates an acid or an alkali is added to the precursor solution by irradiating the precursor solution with light such as ultraviolet light, instead of firing the concave-convex structure layer, energy typified by ultraviolet light such as excimer UV light is used. By irradiating the line, the concave-convex structure layer can be mainly cured.

As described above, the transparent bases 40, 40a, 40b composed of the base materials 42, 42a, 42b and the concave-convex structure layers 50, 50a, 50b as shown in FIGS. 1 (a), (b), and (c). Can be obtained.

As the precursor of the inorganic material used for forming the concavo-convex structure layer, instead of the precursor of silica, TiO ₂ , ZnO, ZnS, ZrO ₂ , Al ₂ O ₃ , BaTIO ₃ , SrTiO ₂ , ITO and the like can be used. Precursors may be used.

Further, in addition to the sol-gel method, a concavo-convex structure layer may be formed by using a method using a dispersion of fine particles of an inorganic material, a liquid phase deposition method (LPD: Liquid Phase Deposition), or the like.

Further, in addition to the above-mentioned inorganic material, a curable resin material may be used to form a concavo-convex structural layer. When forming a concavo-convex structure layer using a curable resin, for example, after applying the curable resin to a base material, the coating film is cured while pressing a mold having an concavo-convex pattern against the applied curable resin layer. The uneven pattern of the mold can be transferred to the curable resin layer. The curable resin may be diluted with an organic solvent before being applied. As the organic solvent used in this case, a solvent that dissolves the resin before curing can be selected and used. For example, it can be selected from known ones such as alcohol solvents such as methanol, ethanol and isopropyl alcohol (IPA), and ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone (MIBK). Examples of the method for applying the curable resin include spin coating method, spray coating method, dip coating method, dropping method, gravure printing method, screen printing method, letterpress printing method, die coating method, curtain coating method, inkjet method, and spatter. Various coating methods such as the law can be adopted. As the mold having the uneven pattern, a desired mold such as a film mold or a metal mold can be used. Further, the conditions for curing the curable resin vary depending on the type of resin used, but for example, the curing temperature is in the range of room temperature to 250 ° C., and the curing time is in the range of 0.5 minutes to 3 hours. It is preferable to have. Further, a method of curing by irradiating an energy ray such as an ultraviolet ray or an electron beam may be used, and in that case, the irradiation amount is preferably in the range ^{of 20 mJ / cm 2 to} 10 J / cm ^2.

The transparent substrate 40c in which the structure forming the convex portion 60c is formed on the substrate 42c as shown in FIG. 1D can be manufactured, for example, as follows. In the above-mentioned production method, instead of applying the precursor solution of the inorganic material on the base material, the precursor solution is applied only to the concave portion or the convex portion of the concave-convex pattern transfer mold. In the pressing step, the precursor solution applied to the mold is brought into close contact with the base material, and the precursor solution is transferred to the base material. As a result, a convex portion having a shape corresponding to the shape of the concave portion or the convex portion of the mold is formed on the base material.

Further, as shown in FIG. 1 (e), the transparent substrate 40d made of the base material shaped so that the surface of the base material itself constitutes the uneven pattern 80d composed of the convex portions 60d is, for example, the following. It can be manufactured in this way. A resist layer having an uneven pattern is formed on a substrate by a known technique such as nanoimprint or photolithography. After etching the recesses of the resist layer to expose the surface of the base material, the base material is etched using the remaining resist layer as a mask. After etching, the remaining mask (resist) is removed with a chemical solution. By the above operation, the uneven pattern 80d can be formed on the surface of the base material itself.

<High refractive index layer forming process>
Next, a high refractive index layer is formed on the transparent substrate on which the uneven pattern is formed (step S2 in FIG. 2). In order to form the high refractive index layer having the above-mentioned film thickness on the upper surface and the side surface of the convex portion of the concave-convex pattern, the high refractive index layer is formed by a film forming method having high coverage. Is preferable, and for example, it can be formed by a plating method, an atomic layer deposition method, a chemical vapor deposition method, a sputtering method, a vapor deposition method, or the like.

<Laminate body forming process>
Next, 2n + 1 (n is a positive integer) layers forming the laminated body are sequentially formed on the high refractive index layer (step S3 in FIG. 2). It is preferable that each layer is formed by a film forming method having low turnability, for example, a sputtering method, a vapor deposition method, or the like. As a result, the thickness of the laminate formed on the high-refractive index layer on the side surface of the convex portion is increased while preventing the material constituting the laminate from being deposited on the high-refractive index layer on the side surface of the convex portion. It is possible to form a laminated body on the high refractive index layer on the upper surface of the convex portion of the concave-convex pattern while controlling within such a range.

As described above, the optical retardation members 100, 100a, 100b, 100c, and 100d as shown in FIGS. 1A to 1E can be manufactured.

An antireflection layer may be formed on the back surface of the base material (the surface opposite to the surface on which the uneven structure layer is formed). Thereby, the optical retardation member 100e as shown in FIG. 1 (f) can be manufactured. The timing of forming the antireflection layer is not particularly limited, but may be performed, for example, before the step S1 for forming the transparent substrate, or after the step S3 for forming the laminate. In particular, it is preferable to form an antireflection layer after the step S3 for the following reasons.

When the antireflection layer is formed before the step S1, it tends to be difficult to use an apparatus (for example, an automatic imprint apparatus) that processes the substrate while automatically transporting the substrate in the subsequent steps. .. This is because the base material on which the antireflection layer is formed does not reflect light, so it is difficult to detect the base material by light such as laser light. In this case, the base material can be detected by performing a process such as removing a part of the antireflection layer or using a detection method other than light (for example, a detection method using a contact sensor). Such a method may lead to an increase in man-hours and costs. Further, when the antireflection layer, the high refractive index layer and the laminated body are formed by the vacuum process, the vacuum process is performed in two steps before and after the transparent substrate forming step S1 performed at normal pressure. , Man-hours and costs tend to increase.

When the antireflection layer is formed after the step S1 and before the step S2, the convex portion of the transparent substrate is formed by rubbing the transparent substrate against the support (susceptor) on which the transparent substrate is placed when the antireflection layer is formed. It may fall over and the uneven pattern may be deformed.

When the antireflection layer is formed after the step S3, the convex portion of the transparent substrate is covered with the high refractive index layer before the antireflection layer is formed, whereby the convex portion of the convex portion is covered as shown in Reference Experiments 1 and 2 described later. Mechanical strength is further improved. Therefore, even if the transparent substrate is rubbed against the support base on which the transparent substrate is placed when the antireflection layer is formed, the convex portion is prevented from falling and the uneven pattern is suppressed from being deformed, and the yield is improved. Further, when the antireflection layer, the high refractive index layer and the laminated body are formed by the vacuum process, the vacuum process can be collectively performed after the transparent substrate forming step S1 performed at normal pressure, so that the man-hours and costs are reduced. Is suppressed.

<Mold for uneven pattern transfer>
Examples of the mold for transferring the uneven pattern used in the method for manufacturing the optical retardation member include a metal mold or a film-shaped resin mold manufactured by the following method. The resin constituting the resin mold also includes rubber such as natural rubber or synthetic rubber. The mold has an uneven pattern on the surface.

An example of a method for manufacturing a mold for transferring an uneven pattern will be described. First, a concavo-convex pattern is formed on a substrate such as silicon, metal, quartz, or resin by a microfabrication method such as a photolithography method, a cutting method, an electron beam direct drawing method, a particle beam beam processing method, or an operation probe processing method. To make a mother mold. The master mold has an uneven pattern consisting of convex portions and concave portions extending linearly in a uniform direction.

After forming the master mold, a mold to which the uneven pattern of the master mold is transferred can be formed by an electroforming method or the like as follows. First, a seed layer to be a conductive layer for electroforming can be formed on a master mold having a concavo-convex pattern by electroless plating, sputtering, vapor deposition, or the like. The seed layer is preferably 10 nm or more in order to make the current density in the subsequent electroplating process uniform and to make the thickness of the metal layer deposited in the subsequent electroforming process constant. Seed layer materials include, for example, nickel, copper, gold, silver, platinum, titanium, cobalt, tin, zinc, chromium, gold / cobalt alloy, gold / nickel alloy, boron / nickel alloy, solder, copper / nickel / chromium. Alloys, tin-nickel alloys, nickel-palladium alloys, nickel-cobalt-phosphorus alloys, or alloys thereof can be used. Next, a metal layer is deposited on the seed layer by electrotyping (electrotyping). The thickness of the metal layer can be, for example, a total thickness of 10 to 30,000 μm including the thickness of the seed layer. As the material of the metal layer to be deposited by electroforming, any of the above metal species that can be used as a seed layer can be used. It is desirable that the formed metal layer has an appropriate hardness and thickness from the viewpoint of ease of processing such as pressing, peeling, and cleaning of the resin layer for the subsequent formation of the mold.

The metal layer including the seed layer obtained as described above is peeled off from the master mold having the uneven pattern to obtain a metal substrate. As a peeling method, it may be physically peeled off, or it may be peeled off by dissolving and removing the material forming the uneven pattern of the mother mold with an organic solvent, an acid, an alkali or the like that dissolves them. .. When the metal substrate is peeled from the master mold, the remaining material components can be removed by cleaning. As a cleaning method, wet cleaning using a surfactant or the like or dry cleaning using ultraviolet rays or plasma can be used. Further, for example, a pressure-sensitive adhesive or an adhesive may be used to adhere and remove the remaining material components. The metal substrate (metal mold) in which the pattern is transferred from the master mold thus obtained can be used as a mold for transferring the uneven pattern used in the production of the optical retardation member of the embodiment.

Further, by using the obtained metal substrate and transferring the uneven pattern of the metal substrate to the film-shaped support substrate, a flexible mold such as a film-shaped mold can be produced. For example, after applying the curable resin to the support substrate, the resin layer is cured while pressing the uneven pattern of the metal substrate against the resin layer. As the support substrate, for example, a base material made of an inorganic material such as glass, quartz, silicon; silicone resin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), cycloolefin polymer (COP), polymethyl Examples thereof include a base material made of an organic material such as methacrylate (PMMA), polystyrene (PS), polyimide (PI), and polyarylate, and a metal material such as nickel, copper, and aluminum. Further, the thickness of the support substrate can be in the range of 1 to 500 μm.

Examples of the curable resin include epoxy-based, acrylic-based, methacrylic-based, vinyl ether-based, oxetane-based, urethane-based, melamine-based, urea-based, polyester-based, polyolefin-based, phenol-based, crosslinked liquid crystal-based, fluorine-based, and silicone. Examples thereof include various resins such as monomers such as systems and polyamides, oligomers and polymers. The thickness of the curable resin is preferably in the range of 0.5 to 500 μm. If the thickness is less than the lower limit, the height of the unevenness formed on the surface of the cured resin layer tends to be insufficient, and if the thickness exceeds the upper limit, the influence of the volume change of the resin that occurs during curing becomes large and the uneven shape is formed satisfactorily. It may not be possible.

Examples of the method for applying the curable resin include spin coating method, spray coating method, dip coating method, dropping method, gravure printing method, screen printing method, letterpress printing method, die coating method, curtain coating method, inkjet method, and spatter. Various coating methods such as the law can be adopted. Further, the conditions for curing the curable resin vary depending on the type of resin used, but for example, the curing temperature is in the range of room temperature to 250 ° C., and the curing time is in the range of 0.5 minutes to 24 hours. It is preferable to have. Further, a method of curing by irradiating an energy ray such as an ultraviolet ray or an electron beam may be used, and in that case, the irradiation amount is preferably in the range ^{of 20 mJ / cm 2 to} 10 J / cm ^2.

Next, the metal substrate is removed from the cured resin layer after curing. The method for removing the metal substrate is not limited to the mechanical peeling method, and a known method can be adopted. The film-shaped resin mold having a cured resin layer having irregularities formed on the support substrate thus obtained can be used as a mold for transferring an concave-convex pattern used for manufacturing the optical retardation member of the embodiment.

Further, the uneven pattern of the metal substrate was transferred by applying a rubber-based resin material on the uneven pattern of the metal substrate obtained by the above method, curing the applied resin material, and peeling it from the metal substrate. A rubber mold can be produced. The obtained rubber mold can be used as a mold for transferring an uneven pattern used in manufacturing the optical retardation member of the embodiment. Natural rubber and synthetic rubber can be used as the rubber-based resin material, and silicone rubber, or a mixture or copolymer of silicone rubber and other materials is particularly preferable. Examples of the silicone rubber include polyorganosiloxane, crosslinked polyorganosiloxane, polyorganosiloxane / polycarbonate copolymer, polyorganosiloxane / polyphenylene copolymer, polyorganosiloxane / polystyrene copolymer, polytrimethylsilylpropine, and poly. 4 Methylpentene or the like is used. Silicone rubber is cheaper than other resin materials, has excellent heat resistance, has high thermal conductivity, is elastic, and is not easily deformed even under high temperature conditions. Therefore, when the uneven pattern transfer process is performed under high temperature conditions. Is suitable for. Further, since the silicone rubber-based material has high gas and water vapor permeability, the solvent and water vapor of the material to be transferred can be easily permeated. Therefore, when a rubber mold is used for the purpose of transferring the uneven pattern to the film of the precursor solution of the resin material or the inorganic material as described later, a silicone rubber-based material is suitable. The surface free energy of the rubber-based material is preferably 25 mN / m or less. As a result, the releasability when the uneven pattern of the rubber mold is transferred to the coating film on the base material is improved, and transfer failure can be prevented. The rubber mold can be, for example, 50 to 1000 mm in length, 50 to 3000 mm in width, and 1 to 50 mm in thickness. Further, if necessary, a mold release treatment may be performed on the uneven pattern surface of the rubber mold.

A roll-shaped mold may be formed by winding the metal mold, the film-shaped mold, or the rubber mold obtained as described above around the outer peripheral surface of the cylindrical substrate roll and fixing the mold. In addition to the above methods, the roll-shaped mold can form a concavo-convex pattern directly on the surface of a roll such as a metal roll by an electron beam drawing method or cutting, or prepare a cylindrical substrate having the concavo-convex pattern. It can also be formed by fitting it into a roll and fixing it.

[projector]
An example of a projector using the optical retardation members 100, 100a, 100b, 100c, and 100d of the above embodiment will be described with reference to FIG. The projector 301 shown in FIG. 4 displays a full-color image defined in the image data on a projection surface such as a screen based on image data supplied from an external device of the projector 301, for example, a PC or a DVD player. Can be done.

The projector 301 is composed of three illumination systems 302 to 304 having different wavelengths of emitted light, three image forming systems 305 to 307 that form images of different colors, and a plurality of image forming systems 305 to 307. It includes an image synthesizing unit 308 that synthesizes the formed images of a plurality of colors, and a projection optical system 309 that projects an image (light) synthesized by the image synthesizing unit 308.

The first illumination system 302 can emit red light L1 (for example, the center wavelength is 630 nm), and the second illumination system 303 can emit green light L2 (for example, the center wavelength is 530 nm). The illumination system 304 of No. 3 can emit blue light L3 (for example, the center wavelength is 440 nm).

The image forming systems of the three image forming systems 305 to 307 are provided corresponding to the respective lighting systems of the three lighting systems 302 to 304, respectively.

The image composition unit 308 is composed of a dichroic prism or the like. In this dichroic prism, a wavelength selection film having a characteristic that red light L1 is reflected and green light L2 and blue light L3 are transmitted, and blue light L3 is reflected and red light L1 and green light L2 are transmitted. The structure is such that the wavelength selection film having the characteristic of transmitting light is provided at right angles to each other. Lights L1 to L3 emitted from the three illumination systems 302 to 304 and passing through the three image forming systems 305 to 307 are transmitted or reflected by two types of wavelength selection planes of the image synthesizing unit 308, so that the light L1 to L3 will eventually be transmitted or reflected. Also travel in the same direction and are combined so that they overlap each other on the projection surface. The lights L1 to L3 superimposed on each other become light indicating a full-color image as a whole. When this light is imaged on the projection surface by the projection optical system 309, a full-color image is displayed on the projection surface.

The first illumination system 302 includes a light generation mechanism 310, a condenser lens 311 and a rod lens 312. The light generation mechanism 310 may include a laser diode (LD). This laser diode has an active layer that emits light by a current supplied from a driver, and a resonator capable of laser oscillating the light emitted from the active layer. Alternatively, the light generation mechanism 310 may have a non-polarized light source and a polarizer that produces linearly polarized light from unpolarized light such as a polarization beam splitter. As a result, the light generation mechanism 310 can generate light having substantially linearly polarized light as red light L1. The rod lens 312 can make the light intensity distribution of the light passing through the rod lens 312 uniform. The condensing lens 311 condenses the light L1 so that the spot of the light L1 emitted from the light generation mechanism 310 fits on one end surface of the rod lens 312 in the axial direction.

The second illumination system 303 and the third illumination system 304 are both configured to include a light generation mechanism, a condenser lens, and a rod lens, and the wavelengths of the light emitted from the light generation mechanism are different from each other. Except for this, the configuration is the same as that of the first lighting system 302. The light generation mechanism capable of generating green light L2 includes, for example, a laser diode having an active layer and a resonator that emits infrared light, and a wavelength conversion element such as a PPLN provided inside or outside the resonator. May have.

The light L1 emitted from the first illumination system 302 is reflected by the reflection mirror 313 and then enters the first image forming system 305. The light L2 emitted from the second illumination system 303 is incident on the second image forming system 306, and the light L3 emitted from the third illumination system 304 is reflected by the reflection mirror 314 and then the third image. It is incident on the forming system 307.

The three image forming systems 305 to 307 are arranged on a transmissive liquid crystal panel as an image display element, an incident side wave plate arranged on the light incident side of the liquid crystal panel, and a light emitting side of the liquid crystal panel, respectively. It has an emission side wave plate. The incident side wave plate of each image forming system has a retardation set to a quarter of the central wavelength of the light emitted from the corresponding illumination system. The emission side wave plate of each image forming system has the same retardation as the incident side wave plate of this image forming system. The retardation is a value obtained by multiplying the difference between the refractive index in the direction parallel to the slow phase axis and the refractive index in the direction parallel to the phase advance axis by the thickness of the wave plate.

Specifically, the incident side wavelength plate 320 and the emitting side wave plate 321 of the first image forming system 305 have retardation set to a quarter of the center wavelength of the red light L1 emitted from the first illumination system 302. Has been done. In the incident side wavelength plate 322 and the emitting side wavelength plate 323 of the second image forming system 306, retardation is set to a quarter of the center wavelength of the green light L2 emitted from the second illumination system 303. .. The incident side wavelength plate 324 and the emitting side wavelength plate 325 of the third image forming system 307 have retardation set to a quarter of the center wavelength of the blue light L3 emitted from the third illumination system 304. .. As described above, the retardation of the incident side wave plate and the outgoing side wave plate is different from each other in the three image forming systems 305 to 307.

The image forming system 305-307 includes an incident-side polarizing plate, an optical compensation plate, a liquid crystal panel, and an emitting-side polarizing plate, respectively, in addition to the incident-side wave plate and the exit-side wave plate. The three image forming systems 305 to 307 differ from each other in the retardation of the incident side wave plate in the three image forming systems 305 to 307, and the retardation of the emitting side wave plate is three systems 305 to 307. All have the same configuration except that they differ from each other in 307. Here, the configuration of the first image forming system 305 will be typically described.

The red light L1 incident on the first image forming system 305 from the first illumination system 302 passes through the incident side polarizing plate 326 and is incident on the incident side wave plate 320, and is converted into circularly polarized light by the incident side wave plate 320. Will be done. The circularly polarized light emitted from the incident side wave plate 320 enters the liquid crystal panel 328 through the optical compensation plate 327 and is phase-modulated by the liquid crystal panel 328. The light L1 modulated by the liquid crystal panel 328 is incident on the emitting side wave plate 321 and converted into linearly polarized light, and then incidents on the emitting side polarizing plate 329.

FIG. 5 is a diagram showing the relative relationship of the optical axes of each component constituting the first image forming system. Reference numeral AX in FIG. 5 indicates an optical axis from the first illumination system 302 to the synthesis unit 308.

The incident side polarizing plate 326 and the outgoing side polarizing plate 329 are polarizing plates having a characteristic that linearly polarized light parallel to the transmission axis is transmitted, respectively. The transmission axis of the incident side polarizing plate 326 is set so that almost all of the light L1 (almost linearly polarized light) emitted from the first illumination system 302 is transmitted. The transmission axis of the incident side polarizing plate 326 as seen from the optical axis AX is orthogonal to the transmission axis of the emitting side polarizing plate 329.

The incident side wave plate 320 and the outgoing side wave plate 321 are composed of the optical retardation members 100, 100a, 100b, 100c, and 100d of the above embodiment. The slow axis of the incident side wave plate 320 is parallel to the direction in which the transmission axis of the incident side polarizing plate 326 is rotated by 45 ° counterclockwise when viewed from the optical axis AX. The slow axis of the emitting side wave plate 323 is parallel to the direction in which the transmission axis of the incident side polarizing plate 326 is rotated by 135 ° counterclockwise when viewed from the optical axis AX, and is parallel to the slow axis of the incident side wave plate 320. It is orthogonal.

In the incident side wave plate 320 and the emitting side wave plate 321 respectively, the light incident surface on which the light L1 emitted from the first illumination system 302 is incident is adjacent to the void (air layer), and the light L1 is The emitted light emitting surface is also adjacent to the void. That is, the incident-side wave plate 320 is attached so as to have a gap between the incident-side polarizing plate 326 and the optical compensating plate 327. Further, the emitting side wave plate 321 is attached so as to have a gap between the liquid crystal panel 328 and the emitting side polarizing plate 329.

The projector 301 is provided with a wave plate corresponding to each lighting system on a one-to-one basis in each optical path between each of the plurality of lighting systems and the liquid crystal panel, and each wave plate emits light from the corresponding lighting system. Since the retardation is set to a quarter of the central wavelength of the light to be generated, the light incident on the liquid crystal panel can be converted into circularly polarized light with high accuracy. As a result, the contrast ratio can also be improved.

In the projector 301 shown in FIG. 4, the light generation mechanism 310 that generates light of different colors of red, green, and blue was used in the illumination systems 302 to 304, but instead of this, a single white light source and a single white light source were used. The light from the white light source may be separated into three colors of red, green, and blue by using two die clock mirrors having different reflection band wavelengths.

Next, another example of the projector using the optical retardation members 100, 100a, 100b, 100c, 100d of the above embodiment will be described with reference to FIG.

The projector 501 of FIG. 6 includes three illumination systems 502, 503, and 504 having different wavelengths of emitted light, a liquid crystal panel 528, an image compositing unit 508, and a projection optical system 509.

Of the three lighting systems 502, 503, and 504, the first lighting system 502 can emit red light L1, the second lighting system 503 can emit green light L2, and the third lighting system 503 can emit green light L2. The lighting system 504 can emit blue light L3.

The liquid crystal panel 528 uses the two-dimensional red liquid crystal panel 528R that photomodulates the light emitted from the first lighting system 502 according to the image information and the light emitted from the second lighting system 503 as image information. It is composed of a two-dimensional green liquid crystal panel 528G that is light-modulated accordingly, and a two-dimensional blue liquid crystal panel 528B that light-modulates the light emitted from the third lighting system 504 according to the image information.

The image synthesizing unit 508 is composed of a dichroic prism or the like, and synthesizes each color light modulated by each liquid crystal panel 528R, 528G, 528B.

The projection optical system 509 projects the light synthesized by the image synthesizing unit 508 onto the screen 550.

When viewed along the optical path of the light emitted from the light generation mechanism 510, the three illumination systems 502 to 504 include the light generation mechanism 510, the wave plate 534, the diffuser element (scattering element) 532, and the condenser lens 511. The configuration is arranged in order. In the three lighting systems 502 to 504, a driving device 515 is attached to each diffusion element 532.

Each light generation mechanism 510 may include a laser diode (LD) (not shown). This laser diode has an active layer that emits light by a current supplied from a driver (not shown), and a resonator capable of laser oscillating the light emitted from the active layer. Alternatively, the light generation mechanism 510 may have a non-polarized light source and a polarizer that produces linearly polarized light from unpolarized light such as a polarization beam splitter. As a result, each light generation mechanism 510 can generate substantially linearly polarized light as red light L1, green light L2, and blue light L3.

As the wave plate 534, the phase difference members 100, 100a, 100b, 100c, 100d of the above embodiment designed to generate a phase difference of λ / 4 are used. The wave plate 534 can convert the linearly polarized light emitted from the light generation mechanism 510 into circularly polarized light.

The diffusing element 532 has a function of spreading the light emitted from the wave plate 534 into a light beam bundle having a predetermined spot size. As the diffusing element 532, any element such as frosted glass or a hologram element can be used. As the diffusing element, for example, a diffusing element disclosed in JP-A-6-208089, a hologram recording medium disclosed in JP-A-2010-197916, and the like can be used.

The drive device 515 temporally fluctuates the region irradiated with the light of the diffusion element 532. The drive device 515 includes a motor that rotates the diffusion element 532 around a predetermined axis of rotation.

The condensing lens 511 condenses the light emitted from the diffusing element 532 on the liquid crystal panel 528.

Each liquid crystal panel 528 (red liquid crystal panel 528R, green liquid crystal panel 528G, blue liquid crystal panel 528B) is electrically connected to a signal source (not shown) such as a PC that supplies an image signal including image information. The incident light is spatially modulated for each pixel based on the supplied image signal to form a red image, a green image, and a blue image, respectively. The light (formed image) modulated by the red liquid crystal panel element 528R, the green liquid crystal panel 528G, and the blue liquid crystal panel 528B is incident on the image synthesizing unit 508.

The dichroic prism of the image composition unit 508 has a structure in which four triangular prism prisms are bonded to each other. The surface to be bonded in the triangular prism prism is the inner surface of the dichroic prism. On the inner surface of the dichroic prism, a mirror surface that reflects red light R and transmits green light G and a mirror surface that reflects blue light B and transmits green light G are formed orthogonal to each other. The green light G incident on the dichroic prism is emitted as it is through the mirror surface. The red light R and the blue light B incident on the dichroic prism are selectively reflected or transmitted by the mirror surface, and are emitted in the same direction as the emission direction of the green light G. In this way, the three colored lights (images) are superimposed and synthesized, and the combined colored lights are magnified and projected onto the screen 550 by the projection optical system 509.

The laser light source has advantages such as high output, excellent color reproducibility, easy instantaneous lighting, and long life. However, since the laser light is coherent, it is a laser light source. A projector using the above as a light source has a problem that an interference pattern called a speckle is generated on the screen due to interference. In this regard, in the projector 501 of FIG. 6, modes such as polarization, phase, angle, and time of the light emitted from the light generation mechanism 510 are multiplexed by the rotationally driven diffusion element 532, and the occurrence of speckles can be reduced. .. Further, in the projector 501, the λ / 4 wave plate 534 is provided between the light generation mechanism 510 and the diffusion element 532, so that the linearly polarized light emitted from the light generation mechanism 510 is converted into circularly polarized light by the wave plate 534. Above, it can be incident on the diffuser element 532. As a result, the degree of multiplicity after passing through the scattering plate 532 can be doubled when the diffusion plate 532 is not provided, and the speckle can be reduced to 1 / √2 times.

Hereinafter, the optical retardation member of the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

Example 1
Niobide oxide (thickness 13 nm), silicon dioxide (thickness 34 nm), niobium oxide (thickness 115 nm) and silicon dioxide (thickness 115 nm) on one side (back surface) of the white plate glass substrate having a refractive index of 1.52 An antireflection layer having a thickness of 89 nm) is formed, and the period is 180 nm on the opposite surface (surface) of the one surface of the white plate glass substrate, the width of the upper surface of the convex portion is 20 nm, and the width of the lower surface of the convex portion is 180 nm. By forming a concavo-convex pattern having a convex portion height of 330 nm and a refractive index of the convex portion of 1.41, a transparent substrate having the concavo-convex pattern was produced, and the refractive index was 2.37 on the transparent substrate. The structure of the optical retardation member when a certain material was deposited to a thickness of 60 nm to form a high refractive index layer and the first layer, the second layer, and the third layer were formed in this order was obtained by simulation. The materials of the first layer and the third layer are SiO ₂ , which has a refractive index of 1.46 at a wavelength of 550 nm, and the refractive index of the second layer at a wavelength of 550 nm is 2.0, 2.1, 2.2, 2.3. It was set to 2.4 or 2.6. The thicknesses of the first layer, the second layer, and the third layer were 15 to 40 nm (5 nm intervals), 30 to 50 nm (5 nm intervals), and 70 to 110 nm (10 nm intervals), respectively.

For each optical retardation member having the structure obtained by the above calculation, the transmittance at intervals of 10 nm for the wavelength of the irradiation light in the range of 430 to 680 nm was obtained by simulation, and the arithmetic mean (average transmittance) of the values of the transmittance was obtained. ) Was calculated. The transmittance obtained here is the transmittance of the entire optical retardation member including the reflection loss on the back surface of the transparent substrate (the back surface of the white plate glass substrate).

For the optical retardation member having a refractive index of 2.0 in the second layer, the thicknesses of the first layer, the second layer, and the third layer when the average transmittance is maximized, and the average transmittance at this time. (Maximum average transmittance) was calculated. Similarly for the optical retardation member having the refractive index of the second layer of 2.1, 2.2, 2.3, 2.4, and 2.6, the first layer and the first layer have the maximum average transmittance. The thickness of each of the second layer and the third layer, and the maximum average transmittance were determined. That is, for each value of the refractive index of the second layer, the thicknesses of the first layer, the second layer, and the third layer that maximize the average transmittance of the optical retardation portion are obtained, and the average transmittance at this time is obtained. The rate was calculated as the maximum average transmittance.

The graph shown in FIG. 7A shows the value of the maximum average transmittance with respect to the refractive index of the second layer. It was found that when the refractive index of the second layer is 2.1 or more, the maximum average transmittance is 98% or more, and an optical retardation member having a high average transmittance can be obtained.

Example 2
The refractive index of the first layer and the third layer at a wavelength of 550 nm is 1.3, 1.4, 1.5, 1.55, 1.6, and the material of the second layer has a refractive index of 2.37 at a wavelength of 550 nm. The average transmittance of the optical retardation member was determined in the same manner as in Example 1 except that TiO _{2 was used.}

For the optical retardation members having a refractive index of 1.3 in the first layer and the third layer, the thicknesses of the first layer, the second layer, and the third layer when the average transmittance is maximized, and at this time, The average transmittance (maximum average transmittance) of Similarly for the optical retardation members having the refractive indexes of the first layer and the third layer of 1.4, 1.5, 1.55, and 1.6, the first layer and the first layer have the maximum average transmittance. The thickness of each of the second layer and the third layer, and the maximum average transmittance were determined. That is, the thicknesses of the first layer, the second layer, and the third layer that maximize the average transmittance of the optical retardation portion are obtained for each value of the refractive index of the first layer and the third layer. The average transmittance at that time was calculated as the maximum average transmittance.

The graph shown in FIG. 7B shows the value of the maximum average transmittance with respect to the refractive index of the first layer and the third layer. It was found that when the refractive indexes of the first layer and the third layer were 1.55 or less, the maximum average transmittance was 98% or more, and an optical retardation member having a high average transmittance could be obtained.

Examples 3 and 4
An optical retardation member having the same structure as that of the first embodiment except that the refractive indexes and thicknesses of the first layer, the second layer, and the third layer are set to the values shown in the table of FIG. 8 is generated by the optical retardation member. The phase difference at a wavelength of 550 nm, the transmittance at a wavelength of 400 to 700 nm, and the average transmittance (the average value of the transmittance in the wavelength range of 430 to 680 nm) were determined. The material of the first layer and the third layer of _{Example 3 and the material of the third layer of Example 4 is SiO 2} , and the material of the second layer of Examples 3 and 4 is TiO _2. The material of the first layer of Example 4 is NS-LR-C3J (made of JX Nippon Mining & Metals, refractive index 1.71).

Comparative Examples 1 and 2
In order to compare with Examples 3 and 4, the refractive index and the thickness of the first layer were set to the values shown in the table of FIG. 8, and the same as in Example 3 except that the second layer and the third layer were not provided. , The phase difference, transmittance and average transmittance of the optical retardation member were determined. The thickness of the first layer of the optical retardation member of Comparative Example 2 is the total thickness of the first layer, the second layer, and the third layer of the optical retardation member of Example 3 (that is, the thickness of the laminated body). Same as.

Comparative Example 3
In order to compare with Examples 3 and 4, the refractive indexes and thicknesses of the first layer and the second layer were set to the values shown in the table of FIG. 8, and the same as in Example 3 except that the third layer was not provided. , The phase difference, transmittance and average transmittance of the optical retardation member were determined. The total thickness of the first layer and the second layer of the optical retardation member of Comparative Example 3 was set to be the same as the thickness of the laminated body of the optical retardation member of Example 3.

Comparative Example 4
In order to compare with Examples 3 and 4, the optical positions are the same as in Example 4 except that the refractive indexes and thicknesses of the first layer, the second layer and the third layer are set to the values shown in the table of FIG. The phase difference, transmittance and average transmittance of the phase difference member were determined. The total thickness of the laminated body of the optical retardation members of Comparative Example 4 was set to be the same as the thickness of the laminated body of the optical retardation members of Example 4.

Comparative Example 5
In order to compare with Example 3, the average transmittance of the optical retardation member was obtained in the same manner as in Example 3 except that the third layer was not provided.

The values of the average transmittances of the optical retardation members of Examples 3 and 4 and Comparative Examples 1 to 5 are shown in the table of FIG. Further, the phase difference at a wavelength of 550 nm caused by the optical retardation members of Examples 3 and 4 and Comparative Examples 1 to 4 is shown in the table of FIG. 8, and the transmission spectrum at a wavelength of 400 to 700 nm is shown in FIG.

Three layers, a first layer, a second layer, and a third layer, are formed on the high refractive index layer, the refractive index of the first layer is lower than that of the high refractive index layer, and the refractive index of the third layer is the second layer. The lower optical retardation members of Examples 3 and 4 had a transmittance of 97% or more in the range of 430 to 680 nm and an average transmittance of 98% or more as shown in FIG. In the optical retardation members of Examples 3 and 4, the refractive index of the first layer is lower than the refractive index of the second layer.

On the other hand, in the optical retardation member of Comparative Example 1 in which only the first layer is formed on the high refractive index layer, the transmittance changes so as to undulate with respect to the wavelength as shown in FIG. 9 due to the influence of interference. In the wavelength range of 430 to 680 nm, there was a region where the transmittance was lower than that of Examples 3 and 4. Therefore, the average transmittance of the optical retardation member of Comparative Example 1 was lower than that of Examples 3 and 4, and was less than 97%. Similarly, the optical retardation member of Comparative Example 2 in which the laminated body is composed of only the first layer also has a transmittance in the wavelength range of 430 to 680 nm as compared with Examples 3 and 4 as shown in FIG. Was low, and the average transmittance was as low as 92.1%.

As shown in FIG. 9, the optical retardation member of Comparative Example 3 in which the two layers of the first layer and the second layer are formed on the high refractive index layer also has a wavelength of 430 to 430 to that of Examples 3 and 4. The transmittance in the range of 680 nm was low, and the average transmittance was as low as 84.6%. Similarly, the optical retardation member of Comparative Example 5 in which the two layers of the first layer and the second layer are formed on the high refractive index layer also had a low average transmittance of 95.1%.

In the optical retardation member of Comparative Example 4, three layers, a first layer, a second layer, and a third layer, are formed on the high refractive index layer as in Examples 3 and 4, but the third layer It differs from Examples 3 and 4 in that the refractive index is higher than the refractive index of the second layer. As shown in FIG. 9, the optical retardation member of this comparative example had a lower transmittance in the wavelength range of 430 to 680 nm and a lower average transmittance of 82.5% as compared with Examples 3 and 4.

Examples 5-15
The average transmittance of the optical retardation member was determined in the same manner as in Example 3 except that the thicknesses of the first layer, the second layer, and the third layer were set to the values shown in the table of FIG. The values of the average transmittance of the optical retardation members of each embodiment are shown in the table of FIG.

Three layers, a first layer, a second layer, and a third layer, are formed on the high refractive index layer, the refractive index of the first layer is lower than that of the high refractive index layer, and the refractive index of the third layer is the second layer. All of the lower optical retardation members of Examples 5 to 15 had a high average transmittance of 97% or more. Optics of Examples 5-9, which are in the range of 20 to 40 nm, 35 to 55 nm, 100 to 140 nm, and 155 to 210 nm, respectively, of the thickness of the first layer, the thickness of the second layer, the thickness of the third layer, and the thickness of the laminate. The retardation member had an average transmittance of 98% or more, and had a particularly high transmittance.

Reference experiment 1
A silica precursor solution was applied to one surface of the glass substrate to form a coating film. Next, the coating film was cured while pressing the imprinting mold against the coating film, and then the mold was peeled off. As a result, a transparent substrate having a concavo-convex structure layer made of silica was obtained. On the surface of the concavo-convex structure layer, convex portions extending in one direction are arranged at a pitch of 180 nm, and the cross sections on the plane perpendicular to the extending direction of the convex portions are an upper base of 20 nm, a lower base of 180 nm, and a height of 330 nm. An uneven pattern, which is a trapezoidal shape, was formed.

A cotton swab inclined at an angle of 45 degrees with respect to the glass substrate was brought into contact with the surface of the concave-convex structure layer, and the surface of the concave-convex structure layer was scratched three times while applying a load of 3 kg. Next, the two polarizing plates were arranged so as to face each other in the cross Nicol state, and the transparent substrate after scratching was placed between the two polarizing plates. At this time, the optical axis of each polarizing plate and the extending direction of the convex portion of the transparent substrate were arranged so as to form an angle of 45 degrees. Next, when light was irradiated from one polarizing plate side toward the transparent substrate and the light transmitted from the other polarizing plate was visually observed, the scratched portion appeared dark. This indicates that the uneven pattern was deformed by scratching and the phase difference characteristic changed.

Reference experiment 2
Titanium oxide was sputter-deposited on a transparent substrate prepared in the same manner as in Reference Experiment 1 to form a high refractive index layer. The film formation was carried out until the thickness of the high refractive index layer formed on the upper surface of the convex portion of the transparent substrate became 73 nm. Next, silicon dioxide, titanium oxide, and silicon dioxide were sputter-deposited in this order to form a laminate composed of a first layer, a second layer, and a third layer. The first layer, the second layer, and the third layer formed on the high refractive index layer on the upper surface of the convex portion were 18 nm, 36 nm, and 110 nm, respectively. As a result, an optical retardation member was obtained.

In the same manner as in Reference Experiment 1, after scratching the surface of the laminated body of the optical retardation members, the optical retardation members were placed between the two polarizing plates and visually observed. The scratched part appeared to have the same brightness as the other parts. This indicates that the shape of the concavo-convex pattern of the concavo-convex structure layer was maintained even in the scratched portion.

From the results of Reference Experiments 1 and 2, it is considered that the mechanical strength of the uneven pattern was improved by forming the high refractive index layer and the laminate on the transparent substrate.

Although the present invention has been described above with reference to the embodiments and examples, the optical retardation member and the projector of the present invention are not limited to the above embodiments, and are appropriately modified within the scope of the technical idea described in the claims. can do. For example, the material used in the examples is only one example, and any material can be used as long as it satisfies the relationship of the refractive index described in the claims. In the embodiment of the above projector, an example in which the optical retardation member of the present invention is provided at a specific position or arrangement is shown, but the present invention is not limited to this, and the optical retardation member can be provided at any position or arrangement. Further, in the embodiment of the above projector, a projector of a type (3LCD) that projects light transmitted through the liquid crystal panel by using three liquid crystal panels as image display elements has been described as an example, but the light reflected from the liquid crystal panel is used as an example. It can also be applied to a projector of the type to project (LCOS). Further, the present invention can be applied to any type of projector such as a digital light processing (DLP) type projector using a digital mirror device as an image display element.

The optical retardation member of the present invention can exhibit high transmittance in a wide wavelength range, can produce desired retardation characteristics, can be formed by a normal film forming method, and has mechanical strength. Is high. Therefore, the optical retardation member of the present invention is suitably used not only for projectors (projection type display devices) but also for various devices such as reflective or semi-transmissive liquid crystal display devices, optical disk pickup devices, and polarization conversion elements. be able to.

20 Laminate, 22 1st layer, 24 2nd layer, 26 3rd layer 30 High refractive index layer, 40 Transparent substrate, 42 Base material 50 Concavo-convex structure layer, 60 Convex part, 90 Air layer, 80 Concavo-convex pattern 100 Optical position Phase difference members 301, 501 Projector, 320 Incident side wave plate 321 Emission side wave plate 328, 528 Liquid crystal panel, 532 Diffusing element, 534 Wave plate

Claims (13)

An optical phase difference member that generates a phase difference in incident light.
A transparent substrate having a concavo-convex pattern composed of a plurality of convex portions extending in one direction and having a substantially trapezoidal cross section on a plane perpendicular to the extending direction.
A high-refractive index layer formed on the upper surface and the side surface of the convex portion of the transparent substrate and having a higher refractive index than the convex portion.
A laminate composed of 2n + 1 (n is a positive integer) layers formed on the high refractive index layer on the upper surface of the convex portion is provided.
The laminate is formed on the high refractive index layer on the upper surface and the side surface of the convex portion of the transparent substrate.
An air layer exists between the high refractive index layers formed on the opposite side surfaces of the adjacent convex portions.
The laminate is formed on the first layer formed on the high refractive index layer, the second k layer formed on the second k-1 layer (k is an integer of 1 to n), and the second k layer. With the formed second k + 1 layer,
The refractive index of the first layer is lower than that of the high refractive index layer.
An optical retardation member having a refractive index of the second k + 1 layer lower than that of the second k layer. The optical retardation member according to claim 1, wherein the refractive index of the second k-1 layer (k is an integer of 1 to n) is lower than the refractive index of the second k layer. The optical retardation member according to claim 1 or 2, wherein the second k layer and the high refractive index layer are made of the same material. The optical retardation member according to any one of claims 1 to 3, wherein the 2k + 1 layer and the 2k-1 layer are made of the same material. The optical retardation member according to any one of claims 1 to 4, wherein n is 1. The optical retardation member according to claim 5, wherein the refractive index of the second layer is in the range of 2.1 to 2.6. The optical retardation member according to claim 5 or 6, wherein the refractive index of the first layer and the third layer is in the range of 1.3 to 1.55. The optical phase difference according to any one of claims 1 to 7, wherein the thickness of the laminated body formed on the high refractive index layer on the side surface of the convex portion of the transparent substrate is in the range of 5 to 40 nm. Element. The optical retardation member according to any one of claims 1 to 8, wherein the average transmittance in the wavelength range of 430 nm to 680 nm is 97% or more. The optical retardation member according to any one of claims 1 to 9, wherein the material constituting the convex portion is a sol-gel material. A projector comprising the optical retardation member according to any one of claims 1 to 10. A light generation mechanism that generates linearly polarized light,
An incident side wave plate composed of the optical retardation member according to any one of claims 1 to 10 and converting the light emitted from the light generation mechanism into circularly polarized light.
An image display element that modulates the light converted to circularly polarized light,
An emission side wave plate composed of the optical retardation member according to any one of claims 1 to 10 and converting the light modulated by the image display element into linearly polarized light.
A projector including a projection optical system that projects the light modulated by the image display element. A light generation mechanism that generates linearly polarized light,
A wave plate composed of the optical retardation member according to any one of claims 1 to 10 and converting the light emitted from the light generation mechanism into circularly polarized light.
A diffusing element that diffuses the light converted to circularly polarized light,
An image display element that modulates the light diffused by the diffusion element, and
A projector including a projection optical system that projects the light modulated by the image display element.

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