JP6678630B2 - Polarizing plate and optical device having the same - Google Patents
Polarizing plate and optical device having the same Download PDFInfo
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- JP6678630B2 JP6678630B2 JP2017207869A JP2017207869A JP6678630B2 JP 6678630 B2 JP6678630 B2 JP 6678630B2 JP 2017207869 A JP2017207869 A JP 2017207869A JP 2017207869 A JP2017207869 A JP 2017207869A JP 6678630 B2 JP6678630 B2 JP 6678630B2
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- Polarising Elements (AREA)
- Liquid Crystal (AREA)
Description
本発明は、偏光板及びこれを備える光学機器に関する。 The present invention relates to a polarizing plate and an optical device including the same.
偏光板は、吸収軸方向の偏光を吸収し、該吸収軸方向と直交する透過軸方向の偏光を透過させる光学素子である。近年、耐熱性が要求される液晶プロジェクタ等の光学機器において、有機偏光板に代わり、ワイヤグリッド型の無機偏光板が採用され始めている。 The polarizing plate is an optical element that absorbs polarized light in the absorption axis direction and transmits polarized light in the transmission axis direction orthogonal to the absorption axis direction. In recent years, wire grid type inorganic polarizing plates have begun to be used instead of organic polarizing plates in optical devices such as liquid crystal projectors that require heat resistance.
中でも、透明基板側から順に、反射層、誘電体層及び吸収層を有して構成される吸収型の無機偏光板は、高い耐久性を有するため、光密度が大きい液晶プロジェクタ用途で多く使用されている。これらの各無機層は物理成膜法等により形成され、フォトリソ・ドライエッチング技術等により、サブミクロンオーダーのワイヤグリッド型偏光子パターンが形成される。 Above all, an absorption type inorganic polarizing plate having a reflection layer, a dielectric layer and an absorption layer in order from the transparent substrate side has high durability, and therefore is often used in liquid crystal projector applications having a large light density. ing. Each of these inorganic layers is formed by a physical film forming method or the like, and a wire grid type polarizer pattern of a submicron order is formed by a photolithography / dry etching technique or the like.
上記偏光板は、光学特性上、低反射であることが重要であり、反射率が高いと、液晶パネルの誤動作の原因や迷光による画質劣化の原因となる。近年では、液晶プロジェクタの高輝度化や高精細化により、より低反射な偏光板が望まれている。 It is important that the polarizing plate has low reflection in terms of optical characteristics. If the reflectance is high, it causes a malfunction of the liquid crystal panel and a deterioration in image quality due to stray light. In recent years, with the increase in brightness and definition of liquid crystal projectors, a polarizing plate with lower reflection has been desired.
また、偏光板は、実使用上、高湿の環境下に晒される場合がある。この場合には、偏光板の酸化や腐食が生じて光学特性に悪影響を及ぼし、表示画像の２次元的歪や色の歪等が生じるおそれがある。そのため、高い耐久性を有する偏光板が求められている。 Further, the polarizing plate may be exposed to a highly humid environment in practical use. In this case, the polarizing plate may be oxidized or corroded, adversely affecting the optical characteristics, and two-dimensional distortion or color distortion of the displayed image may occur. Therefore, a polarizing plate having high durability is required.
例えば、反射層上に誘電層と吸収層を備え、グリッドが延在する方向に平行な電界成分をもつ偏光波（ＴＥ波（Ｓ波）の反射率を吸収効果と干渉効果により抑制する偏光板が提案されている（例えば、特許文献１参照）。この偏光板では、さらに最外層に保護層を形成することで、耐久性が向上することも開示されている。また、ワイヤグリッド型偏光板の最外層にＳｉを含有する有機保護膜や、この有機保護膜の下にＳｉ酸化膜等のバリア膜が形成された偏光板が提案されている（例えば、特許文献２参照）。 For example, a polarizing plate that includes a dielectric layer and an absorption layer on a reflection layer and suppresses the reflectance of a polarized wave (TE wave (S wave)) having an electric field component parallel to the direction in which the grid extends by an absorption effect and an interference effect (For example, see Patent Document 1.) It is also disclosed that in this polarizing plate, the durability is improved by further forming a protective layer on the outermost layer. There has been proposed an organic protective film containing Si as the outermost layer, and a polarizing plate in which a barrier film such as a Si oxide film is formed under the organic protective film (for example, see Patent Document 2).
また、撥水膜等の保護膜を電子デバイス上に形成する技術として、種々の技術が提案されている。例えば、撥水膜の形成領域を制御する技術として、撥水膜形成用溶液の塗布領域と溶剤の塗布領域とを調整する技術が提案されている（例えば、特許文献３参照）。また、基板表面に濃度の異なる撥水膜を形成する技術が提案されている（例えば、特許文献４参照）。 Various techniques have been proposed as techniques for forming a protective film such as a water-repellent film on an electronic device. For example, as a technique for controlling a formation area of a water-repellent film, a technique of adjusting a coating area of a solution for forming a water-repellent film and a coating area of a solvent has been proposed (for example, see Patent Document 3). In addition, a technique for forming water-repellent films having different concentrations on a substrate surface has been proposed (for example, see Patent Document 4).
しかしながら、特許文献１や２に開示されている偏光板では、十分な耐久性が得られていないのが現状である。また、特許文献３の技術は自動車のウインドーガラスやミラー等を対象とした技術であり、特許文献４の技術はインクジェット等を対象とした技術であり、ワイヤグリッド型偏光板のようなサブミクロンオーダーの小さなパターンに適用するのは困難である。 However, at present, sufficient durability cannot be obtained with the polarizing plates disclosed in Patent Documents 1 and 2. The technology of Patent Document 3 is a technology for window glass and mirrors of automobiles, and the technology of Patent Document 4 is a technology for ink jets and the like. It is difficult to apply to small order patterns.
本発明は上記に鑑みてなされたものであり、その目的は、優れた光学特性を維持しつつ耐久性を向上できる偏光板及び光学機器を提供することにある。 The present invention has been made in view of the above, and an object of the present invention is to provide a polarizing plate and an optical device capable of improving durability while maintaining excellent optical characteristics.
（１） 上記目的を達成するため本発明は、ワイヤグリッド構造を有する偏光板であって、透明基板（例えば、後述の透明基板１０）と、使用帯域の光の波長よりも短いピッチ（例えば、後述のピッチＰ）で前記透明基板上に配列されて所定方向に延在し、光反射性材料からなる反射層（例えば、後述の反射層１２）を有する格子状凸部（例えば、後述の格子状凸部１１）と、を備え、前記格子状凸部が、前記透明基板側から順に、台座（例えば、後述の台座１０ａ）と、前記反射層と、光吸収性材料を含む吸収層（例えば、後述の吸収層１３）と、を有し、前記台座の最小幅が、前記反射層の幅よりも大きく、前記格子状凸部の表面及び前記格子状凸部間に形成される溝の底面部の表面には、これら表面を覆う保護膜（例えば、後述の保護膜２０）が形成され、前記保護膜は少なくとも、前記反射層の側表面を基板側端部から吸収層側端部まで全て覆うように単層で形成される第１保護膜（例えば、後述の第１保護膜２１）と、前記溝の底面部の表面を覆うように単層で形成され且つ有機膜からなる第２保護膜（例えば、後述の第２保護膜２２）と、前記吸収層の表面を覆うように単層で形成され且つ有機膜からなる第３保護膜（例えば、後述の第２保護膜２３）と、を有し、前記透明基板は、ガラスからなり、前記反射層は、アルミニウムまたはアルミニウム合金からなり、前記第１保護膜は、ホスホン酸系撥水膜からなり、前記第２保護膜は、パーフルオロデシルトリエトキシシランからなる偏光板（例えば、後述の偏光板１）を提供する。 (1) In order to achieve the above object, the present invention relates to a polarizing plate having a wire grid structure, comprising a transparent substrate (for example, a transparent substrate 10 described later) and a pitch shorter than the wavelength of light in a band to be used (for example, Lattice-shaped protrusions (for example, lattices described later) that are arranged on the transparent substrate at a pitch P described later, extend in a predetermined direction, and have a reflective layer (for example, a reflective layer 12 described later) made of a light-reflective material Convex portion 11), and the lattice-shaped convex portion includes, in order from the transparent substrate side, a pedestal (for example, a pedestal 10a described later), the reflective layer, and an absorption layer (for example, a light-absorbing material). And the absorption layer 13) described later, wherein the minimum width of the pedestal is larger than the width of the reflection layer, and the surface of the lattice-shaped protrusion and the bottom surface of the groove formed between the lattice-shaped protrusions. A protective film (for example, a protective film described below) 20) is formed, and the protective film is a first protective film (for example, a first protective film to be described later) formed as a single layer so as to cover at least the side surface of the reflective layer from the substrate side end to the absorption layer side end . 1 protective film 21), a second protective film (for example, a second protective film 22 described later) formed of a single layer and made of an organic film so as to cover the surface of the bottom portion of the groove, and a surface of the absorbing layer. A third protective film (for example, a second protective film 23 described later) formed of a single layer and made of an organic film so as to cover the transparent substrate, the transparent substrate is made of glass, and the reflective layer is made of aluminum. Alternatively, the first protective film is made of an aluminum alloy, the first protective film is made of a phosphonic acid-based water-repellent film, and the second protective film is made of a perfluorodecyltriethoxysilane polarizing plate (for example, a polarizing plate 1 described later). I do.
（２） （１）の偏光板において、前記吸収層は、誘電材料をさらに含み且つ前記光吸収性材料と前記誘電材料の混合層からなるものでもよい。 ( 2 ) In the polarizing plate according to ( 1 ), the absorbing layer may further include a dielectric material, and may include a mixed layer of the light absorbing material and the dielectric material.
（３） （１）の偏光板において、前記吸収層は、前記反射層上に形成され且つ誘電材料からなる誘電体層と、前記誘電体層上に形成され且つ前記光吸収性材料からなる光吸収層と、からなるものでもよい。 ( 3 ) In the polarizing plate according to (1) , the absorption layer is formed on the reflection layer and is made of a dielectric material, and light is formed on the dielectric layer and is made of the light-absorbing material. And an absorption layer.
（４） （１）から（３）いずれかの偏光板において、前記第２保護膜と前記第３保護膜は、同一材料からなるものでもよい。 ( 4 ) In any one of ( 1 ) to ( 3 ), the second protective film and the third protective film may be made of the same material.
（５） また本発明は、（１）から（４）いずれかの偏光板を備える光学機器を提供する。 ( 5 ) The present invention also provides an optical device including the polarizing plate according to any one of (1) to ( 4 ).
本発明によれば、優れた光学特性を維持しつつ耐久性を向上できる偏光板及び光学機器を提供できる。 ADVANTAGE OF THE INVENTION According to this invention, the polarizing plate and optical apparatus which can improve durability, maintaining excellent optical characteristics can be provided.
以下、本発明の実施形態について、図面を参照して詳しく説明する。なお、第２実施形態以降の説明において、第１実施形態と共通する構成については同一又は対応する符号を付し、その説明を省略する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the second and subsequent embodiments, the same or corresponding reference numerals are given to the same components as those in the first embodiment, and description thereof will be omitted.
＜第１実施形態＞
［偏光板］
本発明の第１実施形態に係る偏光板は、ワイヤグリッド構造を有する無機偏光板であって、透明基板と、使用帯域の光の波長よりも短いピッチ（周期）で透明基板上に配列されて所定方向に延在する格子状凸部と、を備える。格子状凸部は、透明基板側から順に、反射層と、吸収層と、を有する。また、第１実施形態に係る偏光板は、格子状凸部の表面及び格子状凸部間に形成される溝の底面部の表面を覆う保護膜を備える。
<First embodiment>
[Polarizer]
The polarizing plate according to the first embodiment of the present invention is an inorganic polarizing plate having a wire grid structure, and is arranged on a transparent substrate and at a pitch (period) shorter than a wavelength of light in a use band. A grid-shaped convex portion extending in a predetermined direction. The lattice-shaped protrusion has a reflective layer and an absorption layer in order from the transparent substrate side. Further, the polarizing plate according to the first embodiment includes a protective film that covers the surface of the lattice-shaped protrusions and the surface of the bottom surface of the groove formed between the lattice-shaped protrusions.
図１は、第１実施形態に係る偏光板１を示す断面模式図である。図１に示すように、偏光板１は、使用帯域の光に透明な透明基板１０と、透明基板１０の一方の面上に使用帯域の光の波長よりも短いピッチＰで配列された格子状凸部１１と、を備える。格子状凸部１１は、透明基板１０側から順に、反射層１２と、吸収層１３と、を有する。即ち、偏光板１は、反射層１２、吸収層１３が透明基板１０側からこの順に積層されて形成された格子状凸部１１が、透明基板１０上に一次元格子状に配列されたワイヤグリッド構造を有する。 FIG. 1 is a schematic sectional view showing a polarizing plate 1 according to the first embodiment. As shown in FIG. 1, the polarizing plate 1 includes a transparent substrate 10 that is transparent to light in a use band, and a grid-like pattern arranged on one surface of the transparent substrate 10 at a pitch P shorter than the wavelength of light in the use band. A projection 11. The lattice-shaped convex portion 11 has a reflective layer 12 and an absorbing layer 13 in order from the transparent substrate 10 side. That is, the polarizing plate 1 has a wire grid in which the grid-like convex portions 11 formed by laminating the reflection layer 12 and the absorption layer 13 in this order from the transparent substrate 10 side are arranged on the transparent substrate 10 in a one-dimensional lattice shape. Having a structure.
ここで、図１に示すように格子状凸部１１の延在する方向（所定方向）を、Ｙ軸方向と称する。また、Ｙ軸方向に直交し、透明基板１０の主面に沿って格子状凸部１１が配列する方向を、Ｘ軸方向と称する。この場合、偏光板１に入射する光は、透明基板１０の格子状凸部１１が形成されている側において、好適にはＸ軸方向及びＹ軸方向に直交する方向から入射する。 Here, the direction (predetermined direction) in which the lattice-shaped protrusions 11 extend as shown in FIG. 1 is referred to as a Y-axis direction. In addition, a direction orthogonal to the Y-axis direction and in which the lattice-shaped protrusions 11 are arranged along the main surface of the transparent substrate 10 is referred to as an X-axis direction. In this case, the light incident on the polarizing plate 1 is preferably incident on the side of the transparent substrate 10 where the lattice-shaped convex portions 11 are formed, from directions orthogonal to the X-axis direction and the Y-axis direction.
偏光板１は、透過、反射、干渉及び光学異方性による偏光波の選択的光吸収の４つの作用を利用することで、Ｙ軸方向に平行な電界成分をもつ偏光波（ＴＥ波（Ｓ波））を減衰させ、Ｘ軸方向に平行な電界成分をもつ偏光波（ＴＭ波（Ｐ波））を透過させる。従って、Ｙ軸方向が偏光板１の吸収軸の方向であり、Ｘ軸方向が偏光板１の透過軸の方向である。 The polarizing plate 1 utilizes a polarized wave (TE wave (S wave) having an electric field component parallel to the Y-axis direction by utilizing four actions of transmission, reflection, interference, and selective light absorption of a polarized wave due to optical anisotropy. A), and a polarized wave (TM wave (P wave)) having an electric field component parallel to the X-axis direction is transmitted. Therefore, the Y-axis direction is the direction of the absorption axis of the polarizing plate 1, and the X-axis direction is the direction of the transmission axis of the polarizing plate 1.
偏光板１の格子状凸部１１が形成された側から入射した光は、吸収層１３を通過する際に一部が吸収されて減衰する。吸収層１３を透過した光のうち、偏光波（ＴＭ波（Ｐ波））は高い透過率で反射層１２を透過する。一方、吸収層１３を透過した光のうち、偏光波（ＴＥ波（Ｓ波））は反射層１２で反射される。反射層１２で反射されたＴＥ波は、吸収層１３を通過する際に一部は吸収され、一部は反射して反射層１２に戻る。また、反射層１２で反射されたＴＥ波は、吸収層１３を通過する際に干渉して減衰する。以上のようにして、偏光板１は、ＴＥ波の選択的減衰を行うことにより、所望の偏光特性が得られる。 Light entering from the side of the polarizing plate 1 on which the lattice-shaped convex portions 11 are formed is partially absorbed and attenuated when passing through the absorption layer 13. Of the light transmitted through the absorption layer 13, a polarized wave (TM wave (P wave)) transmits through the reflection layer 12 with a high transmittance. On the other hand, of the light transmitted through the absorption layer 13, a polarized wave (TE wave (S wave)) is reflected by the reflection layer 12. The TE wave reflected by the reflection layer 12 is partially absorbed when passing through the absorption layer 13 and partially reflected to return to the reflection layer 12. Further, the TE wave reflected by the reflection layer 12 interferes and attenuates when passing through the absorption layer 13. As described above, the polarizing plate 1 can obtain desired polarization characteristics by selectively attenuating the TE wave.
格子状凸部１１は、図１に示すように各一次元格子の延在するＹ軸方向（所定方向）から見たとき、つまり所定方向に直交する断面視で、矩形状に形成される。本実施形態の偏光板１では、グリッド先端部は矩形状の吸収層１３で構成され、グリッド脚部は矩形状の反射層１２で構成される。 As shown in FIG. 1, the lattice-shaped protrusion 11 is formed in a rectangular shape when viewed from the Y-axis direction (predetermined direction) in which each one-dimensional lattice extends, that is, in a cross-sectional view orthogonal to the predetermined direction. In the polarizing plate 1 of the present embodiment, the leading end of the grid is constituted by the rectangular absorbing layer 13, and the grid leg is constituted by the rectangular reflecting layer 12.
ここで、偏光板１を格子状凸部１１の延びる方向に沿うＹ軸方向から見たときに、格子状凸部１１のＸ軸方向の繰り返し間隔をピッチＰと称する。格子状凸部１１のピッチＰは、使用帯域の光の波長よりも短ければ特に制限されない。作製の容易性及び安定性の観点から、格子状凸部１１のピッチＰは、例えば、１００ｎｍ〜２００ｎｍが好ましい。この格子状凸部１１のピッチＰは、走査型電子顕微鏡又は透過型電子顕微鏡で観察することにより測定することができる。例えば、走査型電子顕微鏡又は透過型電子顕微鏡を用いて、任意の４箇所についてピッチＰを測定し、その算術平均値を格子状凸部１１のピッチＰとすることができる。 Here, when the polarizing plate 1 is viewed from the Y-axis direction along the direction in which the lattice-like protrusions 11 extend, the repetition interval of the lattice-like protrusions 11 in the X-axis direction is referred to as a pitch P. The pitch P of the lattice-shaped protrusions 11 is not particularly limited as long as it is shorter than the wavelength of light in the used band. From the viewpoints of easiness of production and stability, the pitch P of the lattice-like convex portions 11 is preferably, for example, 100 nm to 200 nm. The pitch P of the lattice-shaped protrusions 11 can be measured by observing with a scanning electron microscope or a transmission electron microscope. For example, using a scanning electron microscope or a transmission electron microscope, the pitch P can be measured at any four points, and the arithmetic average value can be used as the pitch P of the lattice-shaped convex portions 11.
透明基板１０としては、使用帯域の光に対して透光性を示す基板であれば特に制限されず、目的に応じて適宜選択することができる。「使用帯域の光に対して透光性を示す」とは、使用帯域の光の透過率が１００％であることを意味するものではなく、偏光板としての機能を保持可能な透光性を示せばよい。使用帯域の光としては、例えば、波長３８０ｎｍ〜８１０ｎｍ程度の可視光が挙げられる。 The transparent substrate 10 is not particularly limited as long as it is a substrate that transmits light in a use band, and can be appropriately selected depending on the purpose. The expression "transmissive to light in the used band" does not mean that the transmittance of light in the used band is 100%, but a light transmissivity capable of maintaining the function as a polarizing plate. Just show it. Examples of the light in the used band include visible light having a wavelength of about 380 nm to 810 nm.
透明基板１０の主面形状は特に制限されず、目的に応じた形状（例えば、矩形形状）が適宜選択される。透明基板１０の平均厚みは、例えば、０．３ｍｍ〜１ｍｍが好ましい。 The shape of the main surface of the transparent substrate 10 is not particularly limited, and a shape (for example, a rectangular shape) according to the purpose is appropriately selected. The average thickness of the transparent substrate 10 is preferably, for example, 0.3 mm to 1 mm.
透明基板１０の構成材料としては、屈折率が１．１〜２．２の材料が好ましく、ガラス、水晶、サファイア等が挙げられる。コスト及び透光率の観点からは、ガラス、特に石英ガラス（屈折率１．４６）やソーダ石灰ガラス（屈折率１．５１）を用いることが好ましい。ガラス材料の成分組成は特に制限されず、例えば光学ガラスとして広く流通しているケイ酸塩ガラス等の安価なガラス材料を用いることができる。 As a constituent material of the transparent substrate 10, a material having a refractive index of 1.1 to 2.2 is preferable, and examples thereof include glass, quartz, and sapphire. From the viewpoint of cost and light transmittance, it is preferable to use glass, particularly quartz glass (refractive index 1.46) or soda-lime glass (refractive index 1.51). The component composition of the glass material is not particularly limited, and an inexpensive glass material such as silicate glass widely distributed as an optical glass can be used.
また、熱伝導性の観点からは、熱伝導性が高い水晶やサファイアを用いることが好ましい。これにより、強い光に対して高い耐光性が得られ、発熱量の多いプロジェクタの光学エンジン用の偏光板として好ましく用いられる。 Further, from the viewpoint of thermal conductivity, it is preferable to use quartz or sapphire having high thermal conductivity. As a result, high light resistance to strong light is obtained, and it is preferably used as a polarizing plate for an optical engine of a projector that generates a large amount of heat.
なお、水晶等の光学活性の結晶からなる透明基板を用いる場合には、結晶の光学軸に対して平行方向又は垂直方向に格子状凸部１１を配置することが好ましい。これにより、優れた光学特性が得られる。ここで、光学軸とは、その方向に進む光のＯ（常光線）とＥ（異常光線）の屈折率の差が最小となる方向軸である。 In the case where a transparent substrate made of an optically active crystal such as quartz is used, it is preferable to arrange the lattice-shaped protrusions 11 in a direction parallel or perpendicular to the optical axis of the crystal. Thereby, excellent optical characteristics can be obtained. Here, the optical axis is a direction axis in which the difference in the refractive index between O (ordinary ray) and E (extraordinary ray) of the light traveling in that direction is minimized.
反射層１２は、透明基板１０上に形成され、吸収軸であるＹ軸方向に帯状に延びた金属膜が配列されてなるものである。より詳しくは、反射層１２は、透明基板１０から垂直に延びている。この反射層１２は、ワイヤグリッド型偏光子としての機能を有し、反射層１２の長手方向に平行な方向に電界成分をもつ偏光波（ＴＥ波（Ｓ波））を減衰させ、反射層１２の長手方向に直交する方向に電界成分をもつ偏光波（ＴＭ波（Ｐ波））を透過させる。 The reflective layer 12 is formed on the transparent substrate 10 and is formed by arranging metal films extending in a band shape in the Y-axis direction which is the absorption axis. More specifically, the reflection layer 12 extends vertically from the transparent substrate 10. The reflective layer 12 has a function as a wire grid polarizer, attenuates a polarized wave (TE wave (S wave)) having an electric field component in a direction parallel to the longitudinal direction of the reflective layer 12, and A polarized wave (TM wave (P wave)) having an electric field component in a direction orthogonal to the longitudinal direction of the light is transmitted.
反射層１２の構成材料としては、使用帯域の光に対して反射性を有する光反射性材料であれば特に制限されず、例えば、Ａｌ、Ａｇ、Ｃｕ、Ｍｏ、Ｃｒ、Ｔｉ、Ｎｉ、Ｗ、Ｆｅ、Ｓｉ、Ｇｅ、Ｔｅ等の元素単体又はこれらの１種以上の元素を含む合金が挙げられる。中でも、反射層１２は、アルミニウム又はアルミニウム合金で構成されることが好ましい。なお、これらの金属材料以外にも、例えば着色等により表面の反射率が高く形成された金属以外の無機膜や樹脂膜で反射層１２を構成してもよい。反射層１２の膜厚は、特に制限されず、例えば、１００ｎｍ〜３００ｎｍが好ましい。本実施形態では、反射層１２の幅は吸収層１３の幅と同一に設定されている。 The constituent material of the reflective layer 12 is not particularly limited as long as it is a light-reflective material having reflectivity to light in a use band. For example, Al, Ag, Cu, Mo, Cr, Ti, Ni, W, A simple element such as Fe, Si, Ge, and Te, or an alloy containing one or more of these elements may be used. Above all, the reflection layer 12 is preferably made of aluminum or an aluminum alloy. In addition, other than these metal materials, the reflection layer 12 may be formed of an inorganic film or a resin film other than a metal having a high surface reflectance by coloring or the like. The thickness of the reflective layer 12 is not particularly limited, and is preferably, for example, 100 nm to 300 nm. In the present embodiment, the width of the reflection layer 12 is set to be the same as the width of the absorption layer 13.
吸収層１３は、反射層１２上に形成され、吸収軸であるＹ軸方向に帯状に延びて配列されたものである。吸収層１３の構成材料としては、金属材料や半導体材料等の光学定数の消衰定数が零でない、光吸収作用を持つ光吸収性材料の１種以上が挙げられ、適用される光の波長範囲によって適宜選択される。金属材料としては、Ｔａ、Ａｌ、Ａｇ、Ｃｕ、Ａｕ、Ｍｏ、Ｃｒ、Ｔｉ、Ｗ、Ｎｉ、Ｆｅ、Ｓｎ等の元素単体又はこれらの１種以上の元素を含む合金が挙げられる。また、半導体材料としては、Ｓｉ、Ｇｅ、Ｔｅ、ＺｎＯ、シリサイド材料（β−ＦｅＳｉ２、ＭｇＳｉ２、ＮｉＳｉ２、ＢａＳｉ２、ＣｒＳｉ２、ＣｏＳｉ２、ＴａＳｉ等）が挙げられる。これらの材料を用いることにより、偏光板１は、適用される可視光域に対して高い消光比が得られる。中でも、吸収層１３は、Ｆｅ又はＴａを含むとともに、Ｓｉを含んで構成されることが好ましい。 The absorption layer 13 is formed on the reflection layer 12, and extends in a band shape in the Y-axis direction which is the absorption axis. Examples of the constituent material of the absorption layer 13 include one or more light-absorbing materials having a light-absorbing action, such as a metal material and a semiconductor material, having an extinction constant of an optical constant that is not zero. Is selected as appropriate. Examples of the metal material include elemental elements such as Ta, Al, Ag, Cu, Au, Mo, Cr, Ti, W, Ni, Fe, and Sn, and alloys containing one or more of these elements. Examples of semiconductor materials include Si, Ge, Te, ZnO, and silicide materials (β-FeSi 2 , MgSi 2 , NiSi 2 , BaSi 2 , CrSi 2 , CoSi 2 , TaSi, and the like). By using these materials, the polarizing plate 1 can obtain a high extinction ratio with respect to the applied visible light region. Above all, it is preferable that the absorption layer 13 includes Fe or Ta and also includes Si.
吸収層１３として半導体材料を用いる場合には、吸収作用に半導体のバンドギャップエネルギーが関与するため、バンドギャップエネルギーが使用帯域以下であることが必要である。例えば、可視光で使用する場合、波長４００ｎｍ以上での吸収、即ち、バンドギャップとしては３．１ｅｖ以下の材料を使用する必要がある。 When a semiconductor material is used for the absorption layer 13, the bandgap energy of the semiconductor needs to be equal to or less than the used band because the bandgap energy of the semiconductor is involved in the absorption action. For example, when using visible light, it is necessary to use a material having an absorption at a wavelength of 400 nm or more, that is, a band gap of 3.1 ev or less.
吸収層１３の膜厚は、特に制限されず、例えば、１０ｎｍ〜１００ｎｍが好ましい。吸収層１３は、蒸着法やスパッタ法により、高密度の膜として形成可能である。 The thickness of the absorption layer 13 is not particularly limited, and is preferably, for example, 10 nm to 100 nm. The absorption layer 13 can be formed as a high-density film by a vapor deposition method or a sputtering method.
また、吸収層１３は、光吸収性材料と誘電材料の混合層からなるものでもよい。光吸収性材料と誘電材料の混合比を変更することにより光吸収性を変更できるため、光反射率の抑制が可能である。光吸収性材料と誘電材料は、膜厚方向に均一に混合されていてもよく、両者の混合比（含有比率）が膜厚方向に変化するように構成してもよい。このときの組成勾配は、線形的に変化するものであってもよく、非線形的（例えば、ステップ式）に変化するものであってもよい。光吸収性材料の含有比率が反射層１２から離隔するに従って増加するように吸収層１３を構成するのが好ましく、これにより、偏光板１の吸収軸反射率Ｒｓを低下させて透過軸透過率Ｔｐを高めることができる。 Further, the absorbing layer 13 may be formed of a mixed layer of a light absorbing material and a dielectric material. By changing the mixing ratio between the light absorbing material and the dielectric material, the light absorbing property can be changed, so that the light reflectance can be suppressed. The light-absorbing material and the dielectric material may be uniformly mixed in the film thickness direction, or the mixture ratio (content ratio) of both may be changed in the film thickness direction. The composition gradient at this time may change linearly or may change non-linearly (for example, in a step formula). It is preferable that the absorption layer 13 be configured such that the content ratio of the light absorbing material increases as the distance from the reflection layer 12 increases, whereby the absorption axis reflectance Rs of the polarizing plate 1 is reduced and the transmission axis transmittance Tp is reduced. Can be increased.
光吸収性材料としては上述のものが挙げられ、誘電材料としては、ＳｉＯ２等のＳｉ酸化物、Ａｌ２Ｏ３、酸化ベリリウム、酸化ビスマス、等の金属酸化物、ＭｇＦ２、氷晶石、ゲルマニウム、二酸化チタン、ケイ素、フッ化マグネシウム、窒化ボロン、酸化ボロン、酸化タンタル、炭素、又はこれらの組み合わせ等の一般的な材料が挙げられる。中でも、誘電材料としてはＳｉ酸化物が好ましく用いられる。 Examples of the light-absorbing material include those described above, and examples of the dielectric material include Si oxides such as SiO 2 , metal oxides such as Al 2 O 3 , beryllium oxide, bismuth oxide, MgF 2 , cryolite, Common materials include germanium, titanium dioxide, silicon, magnesium fluoride, boron nitride, boron oxide, tantalum oxide, carbon, or combinations thereof. Among them, Si oxide is preferably used as the dielectric material.
偏光板１は、上述のような微細なワイヤグリッド構造を有する無機偏光板であるため、使用環境の影響を受け易く、耐酸化性や耐湿性等の高い耐久性が求められる。そのため偏光板１は、耐久性向上のため、格子状凸部１１の表面及び格子状凸部１１間に形成される溝の底面部の表面を覆う保護膜２０を備える。保護膜２０は、有機材料からなる有機膜を含む２種類以上の保護膜で構成される。具体的には図１に示すように、保護膜２０は、第１保護膜２１と、第２保護膜２２と、第３保護膜２３と、を備える。 Since the polarizing plate 1 is an inorganic polarizing plate having a fine wire grid structure as described above, the polarizing plate 1 is easily affected by the use environment and is required to have high durability such as oxidation resistance and moisture resistance. Therefore, the polarizing plate 1 is provided with a protective film 20 that covers the surface of the lattice-shaped protrusions 11 and the bottom surface of the groove formed between the lattice-shaped protrusions 11 in order to improve durability. The protective film 20 is composed of two or more types of protective films including an organic film made of an organic material. Specifically, as shown in FIG. 1, the protective film 20 includes a first protective film 21, a second protective film 22, and a third protective film 23.
第１保護膜２１は、反射層１２の表面を覆うように形成される。より詳しくは、第１保護膜２１は、格子状凸部１１間に形成される溝の側面部を構成する反射層１２の側面を覆うように形成される。この第１保護膜２１は、有機材料又は無機材料からなる膜で構成される。具体的には、第１保護膜２１としては、ホスホン酸系撥水膜又はアルミニウム系酸化膜からなるものが好ましく用いられる。 The first protective film 21 is formed so as to cover the surface of the reflective layer 12. More specifically, the first protective film 21 is formed so as to cover the side surface of the reflective layer 12 constituting the side surface of the groove formed between the lattice-shaped convex portions 11. The first protective film 21 is formed of a film made of an organic material or an inorganic material. Specifically, as the first protective film 21, a film made of a phosphonic acid-based water-repellent film or an aluminum-based oxide film is preferably used.
ホスホン酸系撥水膜としては、ＦＯＰＡ（perfluoro−n−octylphosphonic acid）からなる撥水膜やＯＤＰＡ（Octadecylphosphonic acid）からなる撥水膜が好ましく例示される。ホスホン酸系撥水膜は、ＣＶＤ（Chemical Vapor Deposition）やＡＬＤ（Atomic Layer Deposition）、ディッピング等により形成可能である。 Preferred examples of the phosphonic acid-based water-repellent film include a water-repellent film composed of FOPA (perfluoro-n-octylphosphonic acid) and a water-repellent film composed of ODPA (Octadecylphosphonic acid). The phosphonic acid-based water-repellent film can be formed by CVD (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), dipping, or the like.
また、アルミニウム系酸化膜としては、アルミナ膜が好ましく例示される。アルミニウム系酸化膜は、アルミニウムからなる反射層１２を熱処理することで、その表面にアルミナ膜を形成可能である。このアルミニウム系酸化膜は、撥水性は無いが反射層１２表面の酸化を防止して保護する機能を有する。 A preferred example of the aluminum-based oxide film is an alumina film. The aluminum-based oxide film can form an alumina film on its surface by heat-treating the reflective layer 12 made of aluminum. This aluminum oxide film has no water repellency, but has a function of preventing and protecting the surface of the reflective layer 12 from oxidation.
第２保護膜２２は、格子状凸部１１間に形成される溝の底面部の表面を覆うように形成される。より詳しくは、上記溝の底面部を構成する透明基板１０の表面と、反射層１２の透明基板１０側の端部における側面を覆うように形成される。この第２保護膜２２は、有機材料からなる有機膜で構成される。具体的には、第２保護膜２２としては、有機シラン系材料からなる有機シラン系撥水膜が好ましく用いられる。中でも、フッ素系シラン化合物のＦＤＴＳ（パーフルオロデシルトリエトキシシラン）や非フッ素系シラン化合物のＯＴＳ（オクタデシルトリクロロシラン）が好ましく用いられる。 The second protective film 22 is formed so as to cover the surface of the bottom surface of the groove formed between the lattice-shaped protrusions 11. More specifically, it is formed so as to cover the surface of the transparent substrate 10 constituting the bottom of the groove and the side surface at the end of the reflective layer 12 on the transparent substrate 10 side. The second protective film 22 is formed of an organic film made of an organic material. Specifically, as the second protective film 22, an organic silane-based water-repellent film made of an organic silane-based material is preferably used. Above all, FDTS (perfluorodecyltriethoxysilane) as a fluorine-based silane compound and OTS (octadecyltrichlorosilane) as a non-fluorine-based silane compound are preferably used.
溝の底面部を構成する透明基板１０としてガラスを用いた場合、上記有機シラン系撥水膜はＳｉとＯが結合して自己組織化することで、ガラス表面に強固に密着して形成される。例えば、ＦＤＴＳは可視光での屈折率が１．４程度でガラスの屈折率に近いため、光学特性上、悪影響を及ぼすことがない。この第２保護膜２２は、ＣＶＤやＡＬＤ、ディッピング等により形成可能である。 When glass is used as the transparent substrate 10 constituting the bottom of the groove, the organic silane-based water-repellent film is firmly adhered to the glass surface by bonding self-organization with Si and O. . For example, FDTS has a refractive index of about 1.4 at visible light, which is close to the refractive index of glass, and therefore has no adverse effect on optical characteristics. This second protective film 22 can be formed by CVD, ALD, dipping, or the like.
第３保護膜２３は、吸収層１３の表面を覆うように形成される。より詳しくは、グリッド先端部を構成する吸収層１３の上面及び側面を覆うように形成される。この第３保護膜２３は、有機材料からなる有機膜で構成される。具体的には、第３保護膜２３としては、上述の第２保護膜２２と同様に、有機シラン系材料からなる有機シラン系撥水膜が好ましく用いられ、中でも、フッ素系シラン化合物のＦＤＴＳや非フッ素系シラン化合物のＯＴＳが好ましく用いられる。この第３保護膜２３は、ＣＶＤやＡＬＤ、ディッピング等により形成可能である。本実施形態の第３保護膜２３は、第２保護膜２２と同一の材料で構成されることが好ましい。 The third protective film 23 is formed so as to cover the surface of the absorption layer 13. More specifically, it is formed so as to cover the upper surface and side surfaces of the absorbing layer 13 constituting the grid tip. The third protective film 23 is formed of an organic film made of an organic material. Specifically, as the third protective film 23, similarly to the above-described second protective film 22, an organic silane-based water-repellent film made of an organic silane-based material is preferably used. OTS of a non-fluorine-based silane compound is preferably used. This third protective film 23 can be formed by CVD, ALD, dipping, or the like. The third protective film 23 of the present embodiment is preferably made of the same material as the second protective film 22.
ここで、アルミニウムからなる反射層１２と、（Ｆｅ５％）Ｓｉからなる吸収層１３と、ＳｉＯ２からなる透明基板１０（即ち、溝の底面部）の各表面に対して、ＦＤＴＳ膜を形成したときの撥水性について説明する。具体的には、これらの各表面にＣＶＤ法によりＦＤＴＳ膜を形成したときの撥水性について、以下の測定条件により接触角を測定して評価した。評価結果を表１に示す。
［接触角測定条件］
測定機器：共和界面科学株式会社製接触角測定器「ＤＭ７００Ｒ」
測定条件：液滴法（液体：水、液量：２〜３μｌ、測定までの待ち時間：１秒）
解析方法：θ／２法
Here, an FDTS film was formed on each surface of the reflection layer 12 made of aluminum, the absorption layer 13 made of (Fe5%) Si, and the transparent substrate 10 made of SiO 2 (that is, the bottom of the groove). The water repellency at that time will be described. Specifically, the water repellency when the FDTS film was formed on each of these surfaces by the CVD method was evaluated by measuring the contact angle under the following measurement conditions. Table 1 shows the evaluation results.
[Contact angle measurement conditions]
Measuring equipment: Contact angle measuring device “DM700R” manufactured by Kyowa Interface Science Co., Ltd.
Measurement conditions: droplet method (liquid: water, liquid volume: 2-3 μl, waiting time until measurement: 1 second)
Analysis method: θ / 2 method
表１中、「ＦＤＴＳ処理前」とはＦＤＴＳ膜を形成する前のものを意味し、「ＦＤＴＳ処理後」とはＦＤＴＳ膜を形成した後のものを意味し、「３００℃アニール後」とはＦＤＴＳ膜を形成した後に３００℃のアニール熱処理を実施したものを意味する。また、表１中の接触角（°）は、上述の接触角測定条件による測定結果を示している。 In Table 1, “before FDTS processing” means a state before forming an FDTS film, “after FDTS processing” means a state after forming an FDTS film, and “after annealing at 300 ° C.” This means that an annealing heat treatment at 300 ° C. is performed after forming the FDTS film. The contact angle (°) in Table 1 indicates a measurement result under the above-described contact angle measurement conditions.
表１の結果から明らかであるように、アルミニウム、（Ｆｅ５％）Ｓｉ及びＳｉＯ２いずれにおいても、表面にＦＤＴＳ膜を形成することにより接触角が飛躍的に大きくなり、撥水性が大きく向上することが分かる。また、（Ｆｅ５％）Ｓｉ及びＳｉＯ２いずれにおいても、高温での熱処理後も高い撥水性が維持されており、高い耐久性（耐熱性）を有することが確認できる。 As is clear from the results in Table 1, the contact angle is significantly increased and the water repellency is greatly improved by forming the FDTS film on the surface of any of aluminum, (Fe5%) Si and SiO 2. I understand. In addition, in both (Fe5%) Si and SiO 2 , high water repellency is maintained even after heat treatment at a high temperature, and it can be confirmed that they have high durability (heat resistance).
これに対してアルミニウムにおいては、ＦＤＴＳ膜形成直後は高い撥水性を示すが、高温で熱処理すると撥水性は極端に低下し、ＦＤＴＳ処理前よりも撥水性が低下することが分かる。これは、アルミニウム表面とＦＤＴＳ膜との密着性が低いため、高温での熱処理によりＦＤＴＳ膜が剥離してアルミニウム表面が酸化し、アルミナ膜が形成されているものと考えられる。この結果から、アルミニウムからなる反射層１２の表面にＦＤＴＳ膜を形成しても、高い耐久性が得られないことが確認できる。この対応策として、ＦＤＴＳ膜を形成する前に偏光板上にシリカ膜をコートすることが考えられるが、この場合には偏光板自体の膜厚が増すことになり、光散乱等により偏光板の光学性能が低下する原因になるため好ましい対応策とは言えない。 On the other hand, aluminum shows high water repellency immediately after the formation of the FDTS film, but when heat treated at a high temperature, the water repellency is extremely reduced, and the water repellency is lower than before the FDTS treatment. This is probably because the adhesion between the aluminum surface and the FDTS film is low, so that the heat treatment at a high temperature peels off the FDTS film and oxidizes the aluminum surface to form an alumina film. From this result, it can be confirmed that even if an FDTS film is formed on the surface of the reflective layer 12 made of aluminum, high durability cannot be obtained. As a countermeasure, it is conceivable to coat a silica film on the polarizing plate before forming the FDTS film. In this case, however, the thickness of the polarizing plate itself increases, and light scattering or the like causes the polarizing plate to be coated. This is not a preferable measure because it causes a decrease in optical performance.
そこで本実施形態では、保護膜２０を形成する対象の構成材料に応じて、保護膜２０の種類を変更し、少なくとも２種類以上の保護膜を偏光板１の最外層に形成することを特徴とする。より詳しくは、上述したように、例えばアルミニウムからなる反射層１２の表面には第１保護膜２１としてＦＯＰＡ膜やＯＤＰＡ膜を形成し、例えばガラスからなる溝の底面部（透明基板１０）の表面やＦｅＳｉとＳｉＯ２の混合物からなる吸収層１３の表面には第２、第３保護膜２２，２３として有機膜のＦＤＴＳ膜を形成する。これにより、熱処理後も良好な撥水機能や酸化防止機能を維持でき、高い耐久性を有する偏光板１が実現可能となっている。なお、保護膜２０の形成方法については、後段で詳述する。 Therefore, the present embodiment is characterized in that the type of the protective film 20 is changed according to the constituent material for forming the protective film 20, and at least two or more types of protective films are formed on the outermost layer of the polarizing plate 1. I do. More specifically, as described above, a FOPA film or an ODPA film is formed as a first protective film 21 on the surface of the reflective layer 12 made of, for example, aluminum, and the surface of the bottom portion (transparent substrate 10) of the groove made of, for example, glass An organic FDTS film is formed as the second and third protective films 22 and 23 on the surface of the absorption layer 13 made of a mixture of FeSi and SiO 2 . Thereby, a favorable water repellent function and an antioxidant function can be maintained even after the heat treatment, and a highly durable polarizing plate 1 can be realized. The method for forming the protective film 20 will be described later in detail.
［偏光板の製造方法］
本実施形態に係る偏光板１の製造方法は、反射層形成工程と、吸収層形成工程と、エッチング工程と、保護層形成工程と、を有する。
[Manufacturing method of polarizing plate]
The method for manufacturing the polarizing plate 1 according to this embodiment includes a reflective layer forming step, an absorbing layer forming step, an etching step, and a protective layer forming step.
反射層形成工程では、透明基板１０上に反射層１２を形成する。吸収層形成工程では、反射層形成工程で形成された反射層１２上に、吸収層１３を形成する。これらの各層形成工程では、例えばスパッタリング法や蒸着法により、各層を形成可能である。 In the reflection layer forming step, the reflection layer 12 is formed on the transparent substrate 10. In the absorbing layer forming step, the absorbing layer 13 is formed on the reflecting layer 12 formed in the reflecting layer forming step. In each of these layer forming steps, each layer can be formed by, for example, a sputtering method or an evaporation method.
エッチング工程では、上述の各層形成工程を経て形成された積層体を選択的にエッチングすることにより、使用帯域の光の波長よりも短いピッチで透明基板１０上に配列される格子状凸部１１を形成する。具体的には、例えばフォトリソグラフィ法やナノインプリント法により、一次元格子状のマスクパターンを形成する。そして、上記積層体を選択的にエッチングすることにより、使用帯域の光の波長よりも短いピッチで透明基板１０上に配列される格子状凸部１１を形成する。エッチング方法としては、例えば、エッチング対象に対応したエッチングガスを用いたドライエッチング法が挙げられる。 In the etching step, the laminate formed through the above-described respective layer forming steps is selectively etched to form the lattice-shaped convex portions 11 arranged on the transparent substrate 10 at a pitch shorter than the wavelength of light in the working band. Form. Specifically, a one-dimensional lattice-like mask pattern is formed by, for example, a photolithography method or a nanoimprint method. Then, by selectively etching the laminated body, the lattice-shaped convex portions 11 arranged on the transparent substrate 10 at a pitch shorter than the wavelength of the light in the used band are formed. Examples of the etching method include a dry etching method using an etching gas corresponding to an etching target.
ここで、図２Ａ〜図２Ｃは、本実施形態に係る偏光板１の製造方法を説明するための図である。より詳しくは、これら図２Ａ〜図２Ｃは、本実施形態に係る偏光板１の製造方法における保護膜形成工程を示している。これら図２Ａ〜図２Ｃを参照して、以下、本実施形態の保護膜形成工程を説明する。 Here, FIGS. 2A to 2C are views for explaining a method for manufacturing the polarizing plate 1 according to the present embodiment. More specifically, FIGS. 2A to 2C show a protective film forming step in the method for manufacturing the polarizing plate 1 according to the present embodiment. With reference to FIGS. 2A to 2C, a protective film forming step of the present embodiment will be described below.
保護膜形成工程では、先ず、図２Ａに示すように、ＣＶＤやＡＬＤにより第２保護膜２２を格子状凸部１１間の溝の底面部の表面に形成する。次いで、図２Ｂに示すように、反射層１２及び吸収層１３の表面を酸素プラズマやＡｒイオンエッチング等でクリーニングした後に、ＣＶＤやＡＬＤにより第１保護膜２１を反射層１２の表面に形成する。次いで、図２Ｃに示すように、吸収層１３の表面を酸素プラズマやＡｒイオンエッチング等でクリーニングした後に、ＣＶＤやＡＬＤにより、第３保護膜２３を吸収層１３の表面に形成する。これにより、残膜の影響を最小限化できる。 In the protective film forming step, first, as shown in FIG. 2A, a second protective film 22 is formed on the bottom surface of the groove between the lattice-shaped protrusions 11 by CVD or ALD. Next, as shown in FIG. 2B, after the surfaces of the reflection layer 12 and the absorption layer 13 are cleaned by oxygen plasma, Ar ion etching, or the like, the first protective film 21 is formed on the surface of the reflection layer 12 by CVD or ALD. Next, as shown in FIG. 2C, after the surface of the absorption layer 13 is cleaned by oxygen plasma or Ar ion etching or the like, the third protective film 23 is formed on the surface of the absorption layer 13 by CVD or ALD. Thereby, the influence of the remaining film can be minimized.
また、例えば第１保護膜２１としてアルミナ膜を形成する場合には、先ず、偏光板作製後に酸素含有雰囲気で加熱することにより、反射層１２の表面にアルミナ膜を形成する。次いで、ＣＶＤやＡＬＤにより、第２保護膜２２を格子状凸部１１間の溝の底面部の表面に形成する。そして、吸収層１３の表面を酸素プラズマやＡｒイオンエッチング等でクリーニングした後に、ＣＶＤやＡＬＤにより、第３保護膜２３を吸収層１３の表面に形成する。 For example, when an alumina film is formed as the first protective film 21, first, an alumina film is formed on the surface of the reflective layer 12 by heating in an oxygen-containing atmosphere after manufacturing the polarizing plate. Next, the second protective film 22 is formed on the bottom surface of the groove between the lattice-shaped protrusions 11 by CVD or ALD. Then, after cleaning the surface of the absorption layer 13 by oxygen plasma, Ar ion etching, or the like, the third protective film 23 is formed on the surface of the absorption layer 13 by CVD or ALD.
以上の各工程を経ることにより、本実施形態に係る偏光板１が製造可能である。 Through the above steps, the polarizing plate 1 according to the present embodiment can be manufactured.
［光学機器］
本実施形態に係る光学機器は、上述した本実施形態に係る偏光板１を備える。光学機器としては、液晶プロジェクタ、ヘッドアップディスプレイ、デジタルカメラ等が挙げられる。本実施形態に係る偏光板１は、有機偏光板に比べて耐熱性に優れる無機偏光板であるため、耐熱性が要求される液晶プロジェクタ、ヘッドアップディスプレイ等の用途に好適である。
[Optical equipment]
The optical device according to the present embodiment includes the above-described polarizing plate 1 according to the present embodiment. Examples of the optical device include a liquid crystal projector, a head-up display, a digital camera, and the like. Since the polarizing plate 1 according to the present embodiment is an inorganic polarizing plate having better heat resistance than an organic polarizing plate, it is suitable for applications such as liquid crystal projectors and head-up displays that require heat resistance.
本実施形態に係る光学機器が複数の偏光板を備える場合、複数の偏光板の少なくとも１つが本実施形態に係る偏光板１であればよい。例えば、本実施形態に係る光学機器が液晶プロジェクタである場合、液晶パネルの入射側及び出射側に配置される偏光板の少なくとも一方が本実施形態に係る偏光板１であればよい。 When the optical device according to the present embodiment includes a plurality of polarizing plates, at least one of the plurality of polarizing plates may be the polarizing plate 1 according to the present embodiment. For example, when the optical apparatus according to the embodiment is a liquid crystal projector, at least one of the polarizing plates disposed on the incident side and the emission side of the liquid crystal panel may be the polarizing plate 1 according to the embodiment.
＜第２実施形態＞
図３は、第２実施形態に係る偏光板１Ａを示す断面模式図である。図３に示すように、第２実施形態に係る偏光板１Ａは、吸収層１３Ａの形状が先細形状である点と、透明基板１０上に台座１０ａを備える点と、第２保護膜２２Ａと第３保護膜２３Ａの構成材料が異なる点が、第１実施形態と相違し、これら相違点以外は第１実施形態と同一の構成である。
<Second embodiment>
FIG. 3 is a schematic sectional view showing a polarizing plate 1A according to the second embodiment. As shown in FIG. 3, the polarizing plate 1A according to the second embodiment has a point that the shape of the absorbing layer 13A is tapered, a point that the base 10a is provided on the transparent substrate 10, a second protective film 22A, and a second protective film 22A. The third protective film 23A is different from the first embodiment in that the constituent material of the protective film 23A is different from that of the first embodiment.
具体的には、本実施形態の吸収層１３Ａは、図３に示すようにＹ軸方向（所定方向）から見たとき、つまり所定方向に直交する断面視で、先細形状を有する。即ち、グリッド先端部を構成する吸収層１３Ａは、所定方向から見たときに、先端側（透明基板１０の反対側）ほど幅が狭くなる方向に側面が傾斜した先細形状を有する。より詳しくは、本実施形態の吸収層１３Ａは、等脚台形状を有する。この吸収層１３Ａの構成材料は、第１実施形態と同様であり、光吸収性材料から構成してもよく、光吸収性材料と誘電材料の混合層（均一又は組成勾配あり）で構成してもよい。あるいは、後述する第３実施形態のように光吸収層と誘電体層の２層構造としてもよい。 Specifically, as shown in FIG. 3, the absorption layer 13A of the present embodiment has a tapered shape when viewed from the Y-axis direction (predetermined direction), that is, in a cross-sectional view orthogonal to the predetermined direction. That is, when viewed from a predetermined direction, the absorption layer 13A constituting the grid tip has a tapered shape in which the side surface is inclined in a direction in which the width decreases toward the tip (the side opposite to the transparent substrate 10). More specifically, the absorption layer 13A of the present embodiment has an equipodal trapezoidal shape. The constituent material of the absorption layer 13A is the same as that of the first embodiment, and may be made of a light-absorbing material or a mixed layer of light-absorbing material and a dielectric material (having a uniform or composition gradient). Is also good. Alternatively, it may have a two-layer structure of a light absorbing layer and a dielectric layer as in a third embodiment described later.
グリッド先端部を構成する吸収層１３Ａを先細形状とすることにより、ＴＭ波の透過率を高めることができる。このようにＴＭ波の透過率が高まる理由としては、グリッド先端部を先細形状とすることにより、角度バラツキを持って入射してくる光に対して散乱を抑制する効果があるためと考えられる。 By making the absorption layer 13A constituting the grid tip portion tapered, the transmittance of the TM wave can be increased. It is considered that the reason why the transmittance of the TM wave is increased as described above is that, by making the tip of the grid tapered, there is an effect of suppressing scattering of incident light with an angle variation.
台座１０ａは、図３に示すようにＹ軸方向（所定方向）から見たとき、つまり所定方向に直交する断面視で、反射層１２と幅が略同一の矩形状を有する。ただし、これに限定されず、例えば所定方向から見たときに、透明基板１０側から反射層１２側に向かうに従い幅が狭まるように側面が傾斜した台形状を有していてもよい。このときの台座１０ａの最小幅は反射層１２の幅以上に設定される。台座１０ａの膜厚は、特に制限されず、例えば１０ｎｍ〜１００ｎｍが好ましい。 As shown in FIG. 3, the pedestal 10a has a rectangular shape having substantially the same width as the reflective layer 12 when viewed from the Y-axis direction (predetermined direction), that is, in a cross-sectional view orthogonal to the predetermined direction. However, the present invention is not limited to this. For example, when viewed from a predetermined direction, it may have a trapezoidal shape in which the side surface is inclined so that the width decreases from the transparent substrate 10 side toward the reflective layer 12 side. At this time, the minimum width of the pedestal 10a is set to be equal to or larger than the width of the reflective layer 12. The thickness of the pedestal 10a is not particularly limited, and is preferably, for example, 10 nm to 100 nm.
台座１０ａは、吸収軸であるＹ軸方向に帯状に延びた誘電体膜が透明基板１０上に配列されてなるものである。台座１０ａの構成材料としては、使用帯域の光に対して透明であり、透明基板１０よりも屈折率の小さい材料が好ましく、中でも、ＳｉＯ２等のＳｉ酸化物が好ましい。 The pedestal 10a is formed by arranging, on the transparent substrate 10, dielectric films extending in a strip shape in the Y-axis direction, which is the absorption axis. As a constituent material of the pedestal 10a, a material that is transparent to light in a use band and has a smaller refractive index than the transparent substrate 10 is preferable, and among them, a Si oxide such as SiO 2 is preferable.
台座１０ａは、例えば、透明基板１０上に形成された上記の誘電体からなる下地層（不図示）に対して、ドライエッチングによる等方性エッチングと異方性エッチングとのバランスを段階的に変化させ、エッチング残りを出さないようにオーバーエッチング処理することによって形成可能である。この場合、台座１０ａは透明基板１０上に形成された下地層上に配置される。 The pedestal 10a changes, for example, the balance between isotropic etching by dry etching and anisotropic etching with respect to an underlayer (not shown) made of the above-mentioned dielectric material formed on the transparent substrate 10 in a stepwise manner. Then, it can be formed by performing an over-etching process so as not to leave an etching residue. In this case, the pedestal 10a is disposed on a base layer formed on the transparent substrate 10.
また、本実施形態では、第２保護膜２２Ａと第３保護膜２３Ａの構成材料が異なっている。具体的には、第３保護膜２３Ａは第１実施形態の第３保護膜２３Ａと同様の構成であるのに対して、第２保護膜２２ＡはＳＯＧ（Spin on Glass）膜で構成されている。即ち、本実施形態の偏光板１Ａは、その表面が３種類の保護膜により保護されており、各層の構成材料により適した保護膜を採用でき、耐久性をより高めることが可能となっている。 In the present embodiment, the constituent materials of the second protective film 22A and the third protective film 23A are different. Specifically, the third protection film 23A has the same configuration as the third protection film 23A of the first embodiment, whereas the second protection film 22A is formed of an SOG (Spin on Glass) film. . That is, the surface of the polarizing plate 1A of the present embodiment is protected by three types of protective films, and a protective film more suitable for the constituent material of each layer can be adopted, so that the durability can be further improved. .
本実施形態の偏光板１Ａは、エッチング工程と保護膜形成工程の一部が相違する以外は、第１実施形態の製造方法と同様の製造方法により製造可能である。
具体的には、エッチング工程において、エッチング条件（ガス流量、ガス圧、出力、透明基板の冷却温度）を最適化することにより、吸収層１３Ａの側面に傾斜を持たせた先細形状を形成可能である。
また、保護膜形成工程において、まず、偏光板作製後にＳＯＧをスピンコートによりコーティングした後、全体を酸素プラズマやＦ系プラズマでエッチングする。溝の底面部のＳＯＧ膜が最も厚くなるため、先にグリッド先端側のＳＯＧ膜がエッチングされ、溝の底面部にのみＳＯＧ膜を残存させることができる。次いで、第１保護膜２１Ａ、第３保護膜２３Ａを第１実施形態と同様に形成することで、３種類の保護膜を形成可能である。
The polarizing plate 1A of the present embodiment can be manufactured by a manufacturing method similar to the manufacturing method of the first embodiment, except that a part of an etching step and a part of a protective film forming step are different.
Specifically, in the etching step, by optimizing the etching conditions (gas flow rate, gas pressure, output, cooling temperature of the transparent substrate), it is possible to form a tapered shape in which the side surface of the absorption layer 13A is inclined. is there.
In the protective film forming step, first, after forming the polarizing plate, SOG is coated by spin coating, and then the whole is etched with oxygen plasma or F-based plasma. Since the SOG film on the bottom of the groove is the thickest, the SOG film on the grid tip side is etched first, and the SOG film can be left only on the bottom of the groove. Next, three types of protection films can be formed by forming the first protection film 21A and the third protection film 23A in the same manner as in the first embodiment.
本実施形態の偏光板１Ａによれば、第１実施形態の偏光板１と同様の効果が奏される。また、本実施形態の偏光板１Ａは、第１実施形態の偏光板１と同様に種々の光学機器に適用可能である。 According to the polarizing plate 1A of the present embodiment, the same effects as those of the polarizing plate 1 of the first embodiment can be obtained. Further, the polarizing plate 1A of the present embodiment can be applied to various optical devices, like the polarizing plate 1 of the first embodiment.
＜第３実施形態＞
図４は、第３実施形態に係る偏光板１Ｂを示す断面模式図である。図４に示すように、第３実施形態に係る偏光板１Ｂは、吸収層１３Ｂの構成が第１実施形態と相違する。具体的には、第３実施形態に係る偏光板１Ｂの吸収層１３Ｂは、反射層１２上に形成され且つ誘電材料からなる誘電体層１３１と、この誘電体層１３１上に形成され且つ光吸収性材料からなる光吸収層１３２と、からなる。
<Third embodiment>
FIG. 4 is a schematic sectional view showing a polarizing plate 1B according to the third embodiment. As shown in FIG. 4, the polarizing plate 1B according to the third embodiment differs from the first embodiment in the configuration of the absorption layer 13B. Specifically, the absorbing layer 13B of the polarizing plate 1B according to the third embodiment includes a dielectric layer 131 formed on the reflective layer 12 and made of a dielectric material, and a dielectric layer 131 formed on the dielectric layer 131 and absorbing light. And a light absorbing layer 132 made of a conductive material.
誘電体層１３１は、反射層１２上に形成され、吸収軸であるＹ軸方向に帯状に延びた誘電体膜が配列されてなるものである。誘電体層１３１は、光吸収層１３２で反射した偏光に対して、光吸収層１３２を透過して反射層１２で反射した偏光の位相が半波長ずれる膜厚で形成される。具体的には、誘電体層１３１の膜厚は、偏光の位相を調整して干渉効果を高めることが可能な１〜５００ｎｍの範囲で適宜設定される。 The dielectric layer 131 is formed on the reflective layer 12, and is formed by arranging dielectric films extending in a band shape in the Y-axis direction which is the absorption axis. The dielectric layer 131 is formed with a thickness such that the phase of the polarized light transmitted through the light absorbing layer 132 and reflected by the reflective layer 12 is shifted by a half wavelength with respect to the polarized light reflected by the light absorbing layer 132. Specifically, the thickness of the dielectric layer 131 is appropriately set in a range of 1 to 500 nm, which can adjust the phase of polarized light to enhance the interference effect.
誘電体層１３１を構成する誘電材料としては、ＳｉＯ２等のＳｉ酸化物、Ａｌ２Ｏ３、酸化ベリリウム、酸化ビスマス、等の金属酸化物、ＭｇＦ２、氷晶石、ゲルマニウム、二酸化チタン、ケイ素、フッ化マグネシウム、窒化ボロン、酸化ボロン、酸化タンタル、炭素、又はこれらの組み合わせ等の一般的な材料が挙げられる。中でも、誘電体層１３１は、Ｓｉ酸化物で構成されることが好ましい。 Examples of the dielectric material constituting the dielectric layer 131 include Si oxide such as SiO 2 , metal oxide such as Al 2 O 3 , beryllium oxide, bismuth oxide, MgF 2 , cryolite, germanium, titanium dioxide, and silicon. , Magnesium fluoride, boron nitride, boron oxide, tantalum oxide, carbon, or a combination thereof. In particular, the dielectric layer 131 is preferably made of a Si oxide.
誘電体層１３１の屈折率は、１．０より大きく、２．５以下であることが好ましい。反射層１２の光学特性は、周囲の屈折率によっても影響を受けるため、誘電体層１３１の材料を選択することで、偏光板特性を制御することができる。また、誘電体層１３１の膜厚や屈折率を適宜調整することにより、反射層１２で反射したＴＥ波について、光吸収層１３２を透過する際に一部を反射して反射層１２に戻すことができ、光吸収層１３２を通過した光を干渉により減衰させることができる。このようにしてＴＥ波の選択的減衰を行うことにより、所望の偏光特性を得ることができる。 The refractive index of the dielectric layer 131 is preferably larger than 1.0 and equal to or smaller than 2.5. Since the optical characteristics of the reflective layer 12 are also affected by the surrounding refractive index, the characteristics of the polarizing plate can be controlled by selecting the material of the dielectric layer 131. In addition, by appropriately adjusting the film thickness and the refractive index of the dielectric layer 131, a part of the TE wave reflected by the reflection layer 12 is reflected when the TE wave is transmitted through the light absorption layer 132 and returned to the reflection layer 12. Accordingly, light passing through the light absorption layer 132 can be attenuated by interference. By selectively attenuating the TE wave in this manner, a desired polarization characteristic can be obtained.
光吸収層１３２は、上述の光吸収性材料からなる。この光吸収層１３２は、従来公知の製膜方法により形成可能である。 The light absorbing layer 132 is made of the light absorbing material described above. The light absorbing layer 132 can be formed by a conventionally known film forming method.
偏光板１Ｂは、誘電体層１３１と光吸収層１３２との間に、拡散バリア層を有していてもよい。即ちこの場合には、格子状凸部１１Ｂは、透明基板１０側から順に、反射層１２と、誘電体層１３１と、拡散バリア層と、光吸収層１３２と、を有する。拡散バリア層を有することにより、光吸収層１３２における光の拡散が防止される。この拡散バリア層は、Ｔａ、Ｗ、Ｎｂ、Ｔｉ等の金属膜で構成される。 The polarizing plate 1B may have a diffusion barrier layer between the dielectric layer 131 and the light absorbing layer 132. That is, in this case, the lattice-shaped convex portion 11B includes the reflective layer 12, the dielectric layer 131, the diffusion barrier layer, and the light absorption layer 132 in this order from the transparent substrate 10 side. With the diffusion barrier layer, diffusion of light in the light absorption layer 132 is prevented. This diffusion barrier layer is formed of a metal film such as Ta, W, Nb, and Ti.
本実施形態の偏光板１Ｂは、吸収層形成工程が相違する以外は第１実施形態と同様の製造方法により製造可能である。
本実施形態の吸収層形成工程では、従来公知の製膜法により、誘電体層を形成した後に、光吸収層を形成する。これにより、偏光板１Ｂが製造可能である。
The polarizing plate 1B of the present embodiment can be manufactured by the same manufacturing method as in the first embodiment except that the step of forming the absorbing layer is different.
In the absorption layer forming step of the present embodiment, the light absorption layer is formed after forming the dielectric layer by a conventionally known film forming method. Thereby, the polarizing plate 1B can be manufactured.
本実施形態の偏光板１Ｂによれば、第１実施形態の偏光板１と同様の効果が奏される。また、本実施形態の偏光板１Ｂは、第１実施形態の偏光板１と同様に種々の光学機器に適用可能である。 According to the polarizing plate 1B of the present embodiment, the same effects as those of the polarizing plate 1 of the first embodiment can be obtained. Further, the polarizing plate 1B of the present embodiment can be applied to various optical devices, similarly to the polarizing plate 1 of the first embodiment.
＜第４実施形態＞
図５は、第４実施形態に係る偏光板１Ｃを示す断面模式図である。図５に示すように、第４実施形態に係る偏光板１Ｃは、吸収層及び第３保護膜を備えていない点が１実施形態と相違する以外は、第１実施形態と同様の構成である。
<Fourth embodiment>
FIG. 5 is a schematic sectional view showing a polarizing plate 1C according to the fourth embodiment. As shown in FIG. 5, the polarizing plate 1C according to the fourth embodiment has the same configuration as that of the first embodiment except that the polarizing plate 1C does not include an absorption layer and a third protective film. .
本実施形態の偏光板１Ｃによれば、第１実施形態の偏光板１と同様の効果が奏される。また、本実施形態の偏光板１Ｃは、第１実施形態の偏光板１と同様に種々の光学機器に適用可能である。 According to the polarizing plate 1C of the present embodiment, the same effects as those of the polarizing plate 1 of the first embodiment can be obtained. Further, the polarizing plate 1C of the present embodiment can be applied to various optical devices, similarly to the polarizing plate 1 of the first embodiment.
なお、本発明は上述の各実施形態に限定されるものではなく、本発明の目的を達成できる範囲での変形及び改良は本発明に含まれる。
例えば本発明の偏光板の用途は、液晶プロジェクタに限られない。透過軸方向の偏光の透過率力が高い偏光板として、種々の用途に利用することが可能である。
Note that the present invention is not limited to the above embodiments, and modifications and improvements as long as the object of the present invention can be achieved are included in the present invention.
For example, the use of the polarizing plate of the present invention is not limited to a liquid crystal projector. As a polarizing plate having a high transmittance of polarized light in the transmission axis direction, it can be used for various applications.
１、１Ａ、１Ｂ、１Ｃ 偏光板
１０ 透明基板
１０ａ 台座
１１、１１Ａ、１１Ｂ、１１Ｃ 格子状凸部
１２ 反射層
１３、１３Ａ、１３Ｂ 吸収層
２０、２０Ａ、２０Ｂ、２０Ｃ 保護膜
２１、２１Ａ、２１Ｂ、２１Ｃ 第１保護膜
２２、２２Ａ、２２Ｂ、２２Ｃ 第２保護膜
２３、２３Ａ、２３Ｂ 第３保護膜
１３１ 誘電体層
１３２ 光吸収層
Ｐ 格子状凸部のピッチ
DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C Polarizing plate 10 Transparent substrate 10a Pedestal 11, 11A, 11B, 11C Lattice convex part 12 Reflection layer 13, 13A, 13B Absorption layer 20, 20A, 20B, 20C Protective film 21, 21A, 21B, 21C First protective film 22, 22A, 22B, 22C Second protective film 23, 23A, 23B Third protective film 131 Dielectric layer 132 Light absorbing layer P Pitch of lattice-shaped protrusions
Claims (5)
透明基板と、
使用帯域の光の波長よりも短いピッチで前記透明基板上に配列されて所定方向に延在し、光反射性材料からなる反射層を有する格子状凸部と、を備え、
前記格子状凸部が、前記透明基板側から順に、台座と、前記反射層と、光吸収性材料を含む吸収層と、を有し、
前記格子状凸部の表面及び前記格子状凸部間に形成される溝の底面部の表面には、これら表面を覆う保護膜が形成され、
前記保護膜は少なくとも、
前記反射層の側表面を覆うように単層で形成される第１保護膜と、
前記溝の底面部の表面を覆うように単層で形成され且つ有機膜からなる第２保護膜と、
前記吸収層の表面を覆うように単層で形成され且つ有機膜からなる第３保護膜と、を有し、
前記透明基板は、ガラスからなり、
前記反射層は、アルミニウムまたはアルミニウム合金からなり、
前記第１保護膜は、ホスホン酸系撥水膜からなり、
前記第２保護膜は、パーフルオロデシルトリエトキシシランからなる偏光板。 A polarizing plate having a wire grid structure,
A transparent substrate,
A grid-shaped convex portion that is arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use band and extends in a predetermined direction, and that has a reflective layer made of a light-reflective material,
The lattice-shaped protrusions, in order from the transparent substrate side, have a pedestal, the reflection layer, and an absorption layer containing a light-absorbing material,
A protective film covering these surfaces is formed on the surface of the lattice-shaped protrusions and on the surface of the bottom surface of the groove formed between the lattice-shaped protrusions,
At least the protective film,
A first protective film formed as a single layer so as to cover a side surface of the reflective layer;
A second protective film formed of a single layer and made of an organic film so as to cover the surface of the bottom portion of the groove;
And a third protective film formed of a single layer and made of an organic film so as to cover the surface of the absorption layer,
The transparent substrate is made of glass,
The reflective layer is made of aluminum or an aluminum alloy,
The first protective film is made of a phosphonic acid-based water-repellent film,
The said 2nd protective film is a polarizing plate which consists of perfluorodecyl triethoxysilane.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811073943.1A CN109581568B (en) | 2017-09-28 | 2018-09-14 | Polarizing plate and optical device provided with same |
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| US6785050B2 (en) * | 2002-05-09 | 2004-08-31 | Moxtek, Inc. | Corrosion resistant wire-grid polarizer and method of fabrication |
| JP4386413B2 (en) * | 2003-08-25 | 2009-12-16 | 株式会社エンプラス | Manufacturing method of wire grid polarizer |
| JP4488033B2 (en) * | 2007-02-06 | 2010-06-23 | ソニー株式会社 | Polarizing element and liquid crystal projector |
| KR100927587B1 (en) * | 2008-04-30 | 2009-11-23 | 삼성모바일디스플레이주식회사 | Liquid crystal display |
| JP5636650B2 (en) * | 2009-08-14 | 2014-12-10 | セイコーエプソン株式会社 | Polarizing element and projection display device |
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| US10054717B2 (en) * | 2015-04-03 | 2018-08-21 | Moxtek, Inc. | Oxidation and moisture barrier layers for wire grid polarizer |
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