JP2008009126A

JP2008009126A - Liquid crystal display element

Info

Publication number: JP2008009126A
Application number: JP2006179361A
Authority: JP
Inventors: Yuji Hayata; 祐二早田
Original assignee: Hiroshima Opt Corp; Kyocera Display Corp
Current assignee: Hiroshima Opt Corp; Kyocera Display Corp
Priority date: 2006-06-29
Filing date: 2006-06-29
Publication date: 2008-01-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element which can achieve such excellent display quality that reflection in a metallic part is hardly observed and can perform excellent display of 2 colors of white and black. <P>SOLUTION: Each member of a back light 7, a second polarizing plate 6, a second retardation plate 5, a liquid crystal cell 3, a first retardation plate 2 and a first polarizing plate 1 is layered in this order from the side opposite from the viewing side of the liquid crystal display element. The first retardation plate 2 is a three-quarter-wave plate and the second retardation plate 5 is a retardation plate having 415-480 nm phase difference. The twist angle of the liquid crystal cell is 230-250°. Each of the second polarizing plate 6, the second retardation plate 5, the liquid crystal cell 3, the first retardation plate 2 and the first polarizing plate 1 are arranged so that each of the absorption axis of the polarizing plate, the stretching axis of the retardation plate and the orientation axis of the liquid crystal cell 3 satisfies a prescribed condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、液晶表示素子に関し、特に、ＳＴＮ（Super Twisted Nematic ）型の液晶セルを有する液晶表示素子に関する。 The present invention relates to a liquid crystal display element, and more particularly to a liquid crystal display element having an STN (Super Twisted Nematic) type liquid crystal cell.

ＳＴＮ型の液晶セルでは、白色および黒色の２色で画像を表示しようとする場合であっても、白色および黒色以外の色が現れてしまう。このような着色を解消するために、ＳＴＮ型の液晶セルと補償層とを組み合わせた液晶表示素子（例えば、ＦＳＴＮやＤＳＴＮ）が知られている。 In an STN type liquid crystal cell, colors other than white and black appear even when an image is displayed in two colors of white and black. In order to eliminate such coloring, a liquid crystal display element (for example, FSTN or DSTN) in which an STN liquid crystal cell and a compensation layer are combined is known.

また、特許文献１には、視認側から、第１偏光板、ねじれ光学補償層、液晶表示パネル、第２偏光板、およびバックライトを順に配置した液晶表示素子が記載されている。特許文献１に記載された液晶表示素子では、ねじれ光学補償層のツイスト角は１７０〜１９０°であり、ねじれ光学補償層の位相差値は６９０〜７８０ｎｍである。また、特許文献１に記載された液晶表示素子では、液晶表示パネルのツイスト角は２３０〜２５０°であり、液晶表示パネルの位相差値は７８０〜９２０ｎｍである。 Patent Document 1 describes a liquid crystal display element in which a first polarizing plate, a twisted optical compensation layer, a liquid crystal display panel, a second polarizing plate, and a backlight are arranged in this order from the viewing side. In the liquid crystal display element described in Patent Document 1, the twist angle of the twisted optical compensation layer is 170 to 190 °, and the retardation value of the twisted optical compensation layer is 690 to 780 nm. Moreover, in the liquid crystal display element described in Patent Document 1, the twist angle of the liquid crystal display panel is 230 to 250 °, and the phase difference value of the liquid crystal display panel is 780 to 920 nm.

また、表示品位を向上させるために、液晶セルにブラックマトリクス（以下、ＢＭと記す。）が設けられる。ＢＭには、金属を使用したＢＭ（以下、メタルＢＭと記す。）や、樹脂にカーボン等を混入させたＢＭ（以下、樹脂ＢＭと記す。）が多用されている。メタルＢＭの例として、低反射の金属クロムおよび酸化クロムの複合膜や、その他の金属薄膜および酸化金属薄膜等を使用したメタルＢＭが挙げられる。また、特許文献２には、ＢＭの材質として金属を選択する例が記載されている。 In order to improve display quality, a black matrix (hereinafter referred to as BM) is provided in the liquid crystal cell. As the BM, a BM using a metal (hereinafter referred to as a metal BM) and a BM in which carbon or the like is mixed into a resin (hereinafter referred to as a resin BM) are frequently used. Examples of the metal BM include a metal BM using a low reflection metal chromium and chromium oxide composite film, other metal thin films, metal oxide thin films, and the like. Patent Document 2 describes an example in which a metal is selected as the material of the BM.

メタルＢＭと樹脂ＢＭとを比較する。反射率が低いという点では樹脂ＢＭが優れている。また、膜厚に対する光学濃度（遮光度）の点ではメタルＢＭが優れている。すなわち、膜厚を薄くしても高い光学濃度が得られるという点ではメタルＢＭが優れている。従って、ＢＭの材質として金属を選択することによって、膜厚が薄くて高遮光度のＢＭを実現することができる。また、ＢＭの膜厚が薄いと、液晶セルの液晶層のセルギャップを制御しやすい。従って、セルギャップを制御しやすくするという点でも、メタルＢＭが優れている。 The metal BM and the resin BM are compared. Resin BM is excellent in that the reflectance is low. In addition, metal BM is superior in terms of optical density (light shielding degree) with respect to film thickness. That is, the metal BM is excellent in that a high optical density can be obtained even if the film thickness is reduced. Therefore, by selecting a metal as the material of the BM, a BM having a thin film thickness and a high light shielding degree can be realized. Moreover, when the film thickness of BM is thin, it is easy to control the cell gap of the liquid crystal layer of the liquid crystal cell. Therefore, the metal BM is excellent in that the cell gap is easily controlled.

また、各画素が配置され画像を表示する表示領域の外周には、透明電極から引き廻される個々の配線が配置される。配線が配置される領域（表示領域の外周領域）を狭くすると、各配線の配線抵抗にばらつきが生じる。また、表示領域の外周領域において各配線がどのように引き廻されるかによって、各配線の抵抗は異なる。外周領域を狭くすることによる配線抵抗のばらつきや、各配線の引き廻し抵抗の差を小さくするために、配線として金属の配線（以下、メタル配線と記す。）が用いられる。また、同様に、補助配線にも金属が用いられる。 Further, individual wirings routed from the transparent electrode are arranged on the outer periphery of the display area in which each pixel is arranged and displays an image. When the area where the wiring is arranged (the outer peripheral area of the display area) is narrowed, the wiring resistance of each wiring varies. The resistance of each wiring varies depending on how each wiring is routed in the outer peripheral area of the display area. Metal wiring (hereinafter referred to as metal wiring) is used as wiring in order to reduce variations in wiring resistance due to narrowing of the outer peripheral region and differences in routing resistance between the wirings. Similarly, metal is used for the auxiliary wiring.

また、特許文献３には、液晶パネルが第１偏光板と第２偏光板の間に配置され、液晶パネルと第１偏光板の間に（２ｎ−１）／４波長板が設けられ、液晶パネルと第２偏光板の間に（２ｍ−１）／４波長板が設けられた液晶表示装置が記載されている。しかし、液晶パネルはＴＦＴであり、各軸角に関する記載はない。 Further, in Patent Document 3, a liquid crystal panel is disposed between a first polarizing plate and a second polarizing plate, and a (2n-1) / 4 wavelength plate is provided between the liquid crystal panel and the first polarizing plate. A liquid crystal display device in which a (2m-1) / 4 wavelength plate is provided between polarizing plates is described. However, the liquid crystal panel is a TFT, and there is no description regarding each axis angle.

特開２００６−７１７４９号公報（段落００１６−００３４，図１）JP 2006-71749 A (paragraphs 0016-0034, FIG. 1) 特開２００６−５３１６９号公報（段落００３２）JP 2006-53169 A (paragraph 0032) 特開２００５−２０８５６８号公報（段落００２３，００５０−００５７、図１３）Japanese Patent Laying-Open No. 2005-208568 (paragraphs 0023, 0050-0057, FIG. 13)

従来のＳＴＮ型の液晶セルと補償層とを組み合わせた液晶表示素子では、ＢＭとしてメタルＢＭを設けたり、配線（補助配線も含む。）としてメタル配線を設けたりすると、外光入射時に金属表面で外光が反射してしまい、その結果、良好な表示品位が得られないという課題が生じていた。特に、液晶表示素子の画素を光透過状態にしたときに良好な表示品位が得られなかった。 In a conventional liquid crystal display element in which a STN type liquid crystal cell and a compensation layer are combined, if a metal BM is provided as a BM or a metal wiring is provided as a wiring (including auxiliary wiring), the surface of the metal is exposed when external light is incident. External light is reflected, and as a result, there is a problem that good display quality cannot be obtained. In particular, good display quality could not be obtained when the pixels of the liquid crystal display element were in a light transmission state.

すなわち、メタルＢＭやメタル配線は金属なので反射率が高く、視認側（画像の観察者側）から外光が入射すると、その光はメタルＢＭやメタル配線の表面で反射する。この反射光が観察者に観察され、良好な表示品位が得られなくなってしまう。 That is, since the metal BM and the metal wiring are metal, the reflectance is high, and when external light enters from the viewing side (image observer side), the light is reflected on the surface of the metal BM or metal wiring. This reflected light is observed by an observer, and good display quality cannot be obtained.

そこで本発明は、金属部分での反射が観察されにくく、良好な表示品位を実現でき、また、良好に白色および黒色の２色表示を行うことができる液晶表示素子を提供することを目的とする。 Accordingly, an object of the present invention is to provide a liquid crystal display element that is less likely to observe reflection at a metal part, can realize good display quality, and can perform two-color display of white and black. .

本発明の態様１は、視認側に配置される第１偏光板と反視認側に配置される第２偏光板との間に、配向膜が設けられた透明基板間に液晶層を有するＳＴＮ型の液晶セルを備える液晶表示素子であって、第１偏光板とＳＴＮ型の液晶セルとの間に、位相差値が４２０〜４８０ｎｍである第１位相差板を備え、第２偏光板とＳＴＮ型の液晶セルとの間に、位相差値が４１５〜４８０ｎｍである第２位相差板を備え、ＳＴＮ型の液晶セルは、金属を使用したブラックマトリクスを有し、ＳＴＮ型の液晶セルのツイスト角は、２３０〜２５０°であり、ＳＴＮ型の液晶セルが有する液晶層の位相差値は、７８０〜９２０ｎｍであり、第１偏光板の吸収軸と第１位相差板の延伸軸とがなす角度のうち小さい方の角度をθ_０とした場合、θ_０は４０〜５０°であり、ＳＴＮ型の液晶セルの視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第１偏光板の吸収軸までの反時計回りの角度をθ_１とした場合、θ_１は５０〜８５°であり、ＳＴＮ型の液晶セルの視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第１位相差板の延伸軸までの反時計回りの角度をθ_２とした場合、θ_２は１００〜１２５°であり、ＳＴＮ型の液晶セルの反視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第２位相差板の延伸軸までの反時計回りの角度をθ_３とした場合、θ_３は５５〜８５°であり、ＳＴＮ型の液晶セルの反視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第２偏光板の吸収軸までの反時計回りの角度をθ_４とした場合、θ_４は１０〜４０°であることを特徴とする液晶表示素子を提供する。 Aspect 1 of the present invention is an STN type having a liquid crystal layer between a transparent substrate provided with an alignment film between a first polarizing plate disposed on the viewing side and a second polarizing plate disposed on the non-viewing side. A liquid crystal display device comprising a liquid crystal cell, comprising: a first retardation plate having a retardation value of 420 to 480 nm between the first polarizing plate and the STN type liquid crystal cell; and the second polarizing plate and the STN. A second retardation plate having a retardation value of 415 to 480 nm is provided between the liquid crystal cell and the STN liquid crystal cell, and the STN liquid crystal cell has a black matrix using a metal, and is a twist of the STN liquid crystal cell. The angle is 230 to 250 °, the retardation value of the liquid crystal layer of the STN type liquid crystal cell is 780 to 920 nm, and the absorption axis of the first polarizing plate and the stretching axis of the first retardation plate are formed. When the smaller one of the angles is θ ₀ , θ ₀ is 40 to 50 °. With the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis of the first polarizing plate is θ ₁ In this case, θ ₁ is 50 to 85 °, and the orientation axis of the first retardation plate when viewed from the viewing side is the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell. when the counterclockwise angle to the theta _2, theta ₂ is 100-125 °, as a reference axis orientation axis of the opposite viewing side of the alignment film STN type liquid crystal cell, when viewed from the viewing side When the counterclockwise angle from the reference axis of the second retardation plate to the stretching axis of the second retardation plate is θ ₃ , θ ₃ is 55 to 85 °, and the orientation of the alignment film on the anti-viewing side of the STN type liquid crystal cell axis as reference axis, the counter-clockwise angle from the reference axis when viewed from the viewing side to the absorption axis of the second polarizer θ If a, theta ₄ provides a liquid crystal display device which is a 10 to 40 °.

本発明の態様２は、態様１において、第２位相差板の延伸軸と第２偏光板の吸収軸とがなす角度のうち小さい方の角度をθ_５とした場合、θ_５は３５〜５５°である液晶表示素子を提供する。 Embodiment 2 of the present invention, in the embodiment 1, when the angle of the smaller one of angles formed stretching axis of the second retardation plate and the absorption axis of the second polarizing plate has a theta _5, theta ₅ 35 to 55 Provide a liquid crystal display element that is

本発明の態様３は、視認側に配置される第１偏光板と反視認側に配置される第２偏光板との間に、配向膜が設けられた透明基板間に液晶層を有するＳＴＮ型の液晶セルを備える液晶表示素子であって、第１偏光板とＳＴＮ型の液晶セルとの間に、位相差値が４２０〜４８０ｎｍである第１位相差板を備え、第２偏光板とＳＴＮ型の液晶セルとの間に、位相差値が４１５〜４８０ｎｍである第２位相差板を備え、ＳＴＮ型の液晶セルは、金属を使用したブラックマトリクスを有し、ＳＴＮ型の液晶セルのツイスト角は、２３０〜２５０°であり、ＳＴＮ型の液晶セルが有する液晶層の位相差値は、７８０〜９２０ｎｍであり、第１偏光板の偏光軸と第１位相差板の延伸軸とがなす角度のうち小さい方の角度をθ_０とした場合、θ_０は４０〜５０°であり、ＳＴＮ型の液晶セルの視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第１偏光板の偏光軸までの反時計回りの角度をθ_１とした場合、θ_１は５０〜８５°であり、ＳＴＮ型の液晶セルの視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第１位相差板の延伸軸までの反時計回りの角度をθ_２とした場合、θ_２は１００〜１２５°であり、ＳＴＮ型の液晶セルの反視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第２位相差板の延伸軸までの反時計回りの角度をθ_３とした場合、θ_３は５５〜８５°であり、ＳＴＮ型の液晶セルの反視認側の配向膜の配向軸を基準軸として、視認側から見たときの基準軸から第２偏光板の偏光軸までの反時計回りの角度をθ_４とした場合、θ_４は１０〜４０°であることを特徴とする液晶表示素子を提供する。 Aspect 3 of the present invention is an STN type having a liquid crystal layer between a transparent substrate provided with an alignment film between a first polarizing plate disposed on the viewing side and a second polarizing plate disposed on the non-viewing side. A liquid crystal display device comprising a liquid crystal cell, comprising: a first retardation plate having a retardation value of 420 to 480 nm between the first polarizing plate and the STN type liquid crystal cell; and the second polarizing plate and the STN. A second retardation plate having a retardation value of 415 to 480 nm is provided between the liquid crystal cell and the STN liquid crystal cell, and the STN liquid crystal cell has a black matrix using a metal, and is a twist of the STN liquid crystal cell. The angle is 230 to 250 °, the retardation value of the liquid crystal layer of the STN type liquid crystal cell is 780 to 920 nm, and the polarization axis of the first polarizing plate and the stretching axis of the first retardation plate are formed. When the smaller one of the angles is θ ₀ , θ ₀ is 40 to 50 °. With the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the polarization axis of the first polarizing plate is θ ₁ In this case, θ ₁ is 50 to 85 °, and the orientation axis of the first retardation plate when viewed from the viewing side is the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell. when the counterclockwise angle to the theta _2, theta ₂ is 100-125 °, as a reference axis orientation axis of the opposite viewing side of the alignment film STN type liquid crystal cell, when viewed from the viewing side When the counterclockwise angle from the reference axis of the second retardation plate to the stretching axis of the second retardation plate is θ ₃ , θ ₃ is 55 to 85 °, and the orientation of the alignment film on the anti-viewing side of the STN type liquid crystal cell axis as reference axis, the counter-clockwise angle from the reference axis when viewed from the viewing side to the polarization axis of the second polarizer θ If a, theta ₄ provides a liquid crystal display device which is a 10 to 40 °.

本発明の態様４は、態様３において、第２位相差板の延伸軸と第２偏光板の偏光軸とがなす角度のうち小さい方の角度をθ_５とした場合、θ_５は３５〜５５°である液晶表示素子を提供する。 According to Aspect 4 of the present invention, in Aspect 3, when the smaller angle among the angles formed by the stretching axis of the second retardation plate and the polarization axis of the second polarizing plate is θ ₅ , θ ₅ is 35 to 55. Provide a liquid crystal display element that is

本発明によれば、ＳＴＮ型の液晶セルの金属部分で外光が反射したとしても、その光を観察者に観察されにくくすることができる。液晶表示素子の画素を光透過状態にしたときであっても、ＳＴＮ型の液晶セルの金属部分で反射した光を観察者に観察されにくくすることができる。また、良好な白色および黒色の２色表示を実現することができる。従って、良好な視認性（表示品位）を実現することができる。 According to the present invention, even if external light is reflected by the metal portion of the STN type liquid crystal cell, the light can be hardly observed by an observer. Even when the pixel of the liquid crystal display element is in a light-transmitting state, light reflected by the metal portion of the STN liquid crystal cell can be made difficult to be observed by an observer. In addition, good white and black two-color display can be realized. Therefore, good visibility (display quality) can be realized.

以下、本発明の実施の形態を図面を参照して説明する。なお、視認側とは、液晶表示素子の画像の観察者側を意味する。また、反視認側とは、液晶表示素子の背面側を意味する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The viewing side means the viewer side of the image of the liquid crystal display element. The counter-viewing side means the back side of the liquid crystal display element.

図１は、本発明の液晶表示素子を示す模式的断面図である。本発明の液晶表示素子は、図１に示すように、第１偏光板１と、第１位相差板２と、液晶セル３と、第２位相差板５と、第２偏光板６と、バックライト７とを備える。液晶表示素子の反視認側（背面側）から、バックライト７、第２偏光板６、第２位相差板５、液晶セル３、第１位相差板２、第１偏光板１の順に積層される。 FIG. 1 is a schematic cross-sectional view showing a liquid crystal display element of the present invention. As shown in FIG. 1, the liquid crystal display element of the present invention includes a first polarizing plate 1, a first retardation plate 2, a liquid crystal cell 3, a second retardation plate 5, a second polarizing plate 6, And a backlight 7. The backlight 7, the second polarizing plate 6, the second retardation plate 5, the liquid crystal cell 3, the first retardation plate 2, and the first polarizing plate 1 are laminated in this order from the non-viewing side (back side) of the liquid crystal display element. The

第１偏光板１は、視認側（画像の観察者側）に配置される偏光板であり、第２偏光板６は、液晶表示素子の反視認側に配置される偏光板である。 The 1st polarizing plate 1 is a polarizing plate arrange | positioned at the visual recognition side (observer side of an image), and the 2nd polarizing plate 6 is a polarizing plate arrange | positioned at the non-visible side of a liquid crystal display element.

第１位相差板２の位相差値は、第１位相差板２の屈折率異方性Δｎ_Ｆ１と第１位相差板２の厚さｄ_Ｆ１との積である。そして、第１位相差板２の位相差値（Δｎ_Ｆ１・ｄ_Ｆ１）は、４２０〜４８０ｎｍであり、特に４３０〜４７０ｎｍであることが好ましい。位相差板の位相差値が４２０〜４８０ｎｍであるということは、その位相差板が３／４波長板であることを意味する。従って、第１位相差板２は、３／４波長板である。第１位相差板２は、第１偏光板１と液晶セル３との間に配置される。 The retardation value of the first retardation plate 2 is the product of the refractive index anisotropy Δn _F1 of the first retardation plate 2 and the thickness d _{F1 of} the first retardation plate 2. The first retardation plate 2 of the retardation (Δn _{_F1} · _d _F1) is 420 to 480 nm, it is particularly preferably 430 to 470 nm. The retardation value of the retardation plate being 420 to 480 nm means that the retardation plate is a 3/4 wavelength plate. Accordingly, the first retardation plate 2 is a 3/4 wavelength plate. The first retardation plate 2 is disposed between the first polarizing plate 1 and the liquid crystal cell 3.

液晶セル３は、ＳＴＮ型の液晶セルであり、透明電極（図示せず。）が設けられた第１透明基板３１と第２透明基板３２との間に液晶層３６を有する。第１透明基板３１は、視認側に配置される透明基板であり、第１位相差板２に隣接する。第２透明基板３２は、反視認側に配置される透明基板であり、第２位相差板５に隣接する。 The liquid crystal cell 3 is an STN type liquid crystal cell, and has a liquid crystal layer 36 between a first transparent substrate 31 and a second transparent substrate 32 provided with a transparent electrode (not shown). The first transparent substrate 31 is a transparent substrate disposed on the viewing side and is adjacent to the first retardation plate 2. The second transparent substrate 32 is a transparent substrate disposed on the counter-viewing side, and is adjacent to the second retardation plate 5.

液晶セル３はＳＴＮ型であり、液晶セル３のツイスト角は２３０〜２５０°である。すなわち、視認側における液晶分子の配向方向と、反視認側における液晶分子の配向方向とのねじれの角度は２３０〜２５０°である。 The liquid crystal cell 3 is an STN type, and the twist angle of the liquid crystal cell 3 is 230 to 250 °. That is, the twist angle between the alignment direction of the liquid crystal molecules on the viewing side and the alignment direction of the liquid crystal molecules on the non-viewing side is 230 to 250 °.

液晶セル３が有する液晶層３６の位相差値は、液晶層３６の屈折率異方性Δｎ_ＬＣとセルギャップ（第１透明基板上の透明電極と第２透明基板上の透明電極との間に挟持される液晶層の厚さ）ｄ_ＬＣとの積である。そして、液晶セル３が有する液晶層３６の位相差値（Δｎ_ＬＣ・ｄ_ＬＣ）は、７８０〜９２０ｎｍに設定される。液晶セル３が有する液晶層３６の位相差値（Δｎ_ＬＣ・ｄ_ＬＣ）は、特に８００〜９００ｎｍに設定されることが好ましい。 The retardation value of the liquid crystal layer 36 of the liquid crystal cell 3 is determined by the refractive index anisotropy Δn _LC of the liquid crystal layer 36 and the cell gap (between the transparent electrode on the first transparent substrate and the transparent electrode on the second transparent substrate). Thickness of the sandwiched liquid crystal layer) d _LC . The retardation value (Δn _LC · d _LC ) of the liquid crystal layer 36 included in the liquid crystal cell 3 is set to 780 to 920 nm. The retardation value (Δn _LC · d _LC ) of the liquid crystal layer 36 included in the liquid crystal cell 3 is particularly preferably set to 800 to 900 nm.

液晶セル３には、メタルＢＭ（金属を用いたＢＭ）３３が配置されていてもよい。図１に示す例では、メタルＢＭ３３が液晶セルの内面（具体的には第１透明基板３１の液晶側の面）に設けられた場合を例示している。例えば、メタルＢＭ３３は、マトリクス状に形成される画素間に設けられる。その場合、メタルＢＭ３３は、視認側から見た場合に格子状になる。また、例えば、メタルＢＭ３３は、画素が形成され画像を表示する表示領域の外周領域に設けられてもよい。なお、例えば、一方の透明基板に設けられる透明電極である列電極（図示せず。）と、もう一方の透明基板に設けられる透明電極である行電極（図示せず。）との交差部分が画素となる。 In the liquid crystal cell 3, a metal BM (BM using metal) 33 may be disposed. In the example illustrated in FIG. 1, the case where the metal BM 33 is provided on the inner surface of the liquid crystal cell (specifically, the liquid crystal side surface of the first transparent substrate 31) is illustrated. For example, the metal BM 33 is provided between pixels formed in a matrix. In that case, the metal BM 33 has a lattice shape when viewed from the viewing side. Further, for example, the metal BM 33 may be provided in an outer peripheral area of a display area where pixels are formed and an image is displayed. For example, an intersection of a column electrode (not shown) that is a transparent electrode provided on one transparent substrate and a row electrode (not shown) that is a transparent electrode provided on the other transparent substrate is provided. It becomes a pixel.

また、個々の透明電極から透明基板の端部（例えば、いずれか一方の透明基板の端部）まで、メタル配線が引き廻される。メタル配線は、表示領域の外周領域に設けられる。 Also, metal wiring is routed from each transparent electrode to the end of the transparent substrate (for example, the end of one of the transparent substrates). The metal wiring is provided in the outer peripheral area of the display area.

第１透明基板３１の液晶側の面には透明電極（図示せず。）が設けられ、さらにその透明電極を覆う配向膜（図示せず。）が設けられる。同様に、第２透明基板３２の液晶側の面にも透明電極（図示せず。）が設けられ、さらにその透明電極を覆う配向膜（図示せず。）が設けられる。配向膜によって、液晶層３６の液晶分子が２３０〜２５０°ねじった状態に配向される。 A transparent electrode (not shown) is provided on the surface of the first transparent substrate 31 on the liquid crystal side, and an alignment film (not shown) covering the transparent electrode is further provided. Similarly, a transparent electrode (not shown) is also provided on the liquid crystal side surface of the second transparent substrate 32, and an alignment film (not shown) covering the transparent electrode is further provided. By the alignment film, the liquid crystal molecules of the liquid crystal layer 36 are aligned in a twisted state by 230 to 250 °.

液晶層３６は、旋光性物質を含有したネマチック液晶である。液晶層３６の液晶分子の配向状態は、電界に応答して変化する。従って、透明電極（図示せず。）によって各透明基板３１，３２間の液晶に対して駆動電圧を印加するか否かによって各画素を遮光状態または光透過状態に変化させることができる。このように画素を遮光状態または光透過状態に変化させることで、黒色表示や白色表示を行う。液晶セル３における着色は、第２位相差板５および第１位相差板２によって解消され、良好な黒色および白色の２色表示を実現することができる。 The liquid crystal layer 36 is a nematic liquid crystal containing an optical rotatory substance. The alignment state of the liquid crystal molecules in the liquid crystal layer 36 changes in response to an electric field. Therefore, each pixel can be changed to a light shielding state or a light transmission state depending on whether or not a driving voltage is applied to the liquid crystal between the transparent substrates 31 and 32 by a transparent electrode (not shown). In this way, black display or white display is performed by changing the pixel to the light-shielding state or the light-transmitting state. Coloring in the liquid crystal cell 3 is eliminated by the second phase difference plate 5 and the first phase difference plate 2, and a good two-color display of black and white can be realized.

第２位相差板５の位相差値は、第２位相差板５の屈折率異方性Δｎ_Ｆ２と第１位相差板２の厚さｄ_Ｆ２との積である。そして、第２位相差板５の位相差値（Δｎ_Ｆ２・ｄ_Ｆ２）は、４１５〜４８０ｎｍであり、特に４２０〜４７０ｎｍであることが好ましい。なお、第２位相差板５は、位相差値が４１５〜４８０ｎｍである位相差板であればよいので、必ずしも３／４波長板である必要はない。第２位相差板５は、液晶セル３と第２偏光板６との間に配置される。また、液晶層３６の位相差値と第２位相差板５の位相差値との関係は比例関係にある。すなわち、液晶層３６の位相差値が大きくなれば、第２位相差板５の位相差値も大きくしたほうがよい。 The retardation value of the second retardation plate 5 is the product of the refractive index anisotropy Δn _F2 of the second retardation plate 5 and the thickness d _{F2 of} the first retardation plate 2. The retardation value of the second retardation plate 5 (Δn _{_F2} · _d _F2) are 415～480Nm, it is particularly preferably 420 to 470 nm. Note that the second retardation plate 5 may be a retardation plate having a retardation value of 415 to 480 nm, and is not necessarily a 3/4 wavelength plate. The second retardation plate 5 is disposed between the liquid crystal cell 3 and the second polarizing plate 6. The relationship between the retardation value of the liquid crystal layer 36 and the retardation value of the second retardation plate 5 is proportional. In other words, if the retardation value of the liquid crystal layer 36 is increased, it is preferable that the retardation value of the second retardation plate 5 is also increased.

第２位相差板５は、例えば１軸延伸によって作成された位相差板である。ただし、第２位相差板５は、１軸延伸によって作成された位相差板に限定されず、２軸延伸によって作成された位相差板であってもよい。なお、位相差板の延伸軸は、位相差板材料を延伸した方向に生じる。ただし、２軸延伸によって作成された位相差板の場合、向きが異なる２つの延伸軸が生じるわけではなく、生じる延伸軸は一方向の延伸軸のみである。すなわち、１軸延伸と２軸延伸のどちらで位相差板を作成する場合であっても、生じる延伸軸は一方向の延伸軸のみである。２軸延伸の場合、２種類の延伸方向のうち屈折率が大きい方向の軸が延伸軸となる。すなわち、位相差板材料をｘ方向およびｙ方向それぞれに延伸して作成した位相差板では、ｘ方向およびｙ方向のうち屈折率が大きな方の方向に延伸軸が生じている。例えば、延伸したｘ方向とｙ方向のそれぞれの屈折率をｎ_ｘ，ｎ_ｙとする。また、位相差板の厚さ方向の屈折率をｎ_ｚとする。このとき、例えばｎ_ｘ＞ｎ_ｚ＞ｎ_ｙであれば、ｘ方向が延伸軸の方向となる。 The second retardation plate 5 is a retardation plate created by, for example, uniaxial stretching. However, the second retardation plate 5 is not limited to the retardation plate created by uniaxial stretching, and may be a retardation plate created by biaxial stretching. In addition, the extending | stretching axis | shaft of a phase difference plate arises in the direction which extended | stretched phase difference plate material. However, in the case of a retardation plate prepared by biaxial stretching, two stretching axes having different directions are not generated, and the generated stretching axis is only a unidirectional stretching axis. That is, regardless of whether the retardation plate is produced by uniaxial stretching or biaxial stretching, the resulting stretching axis is only a unidirectional stretching axis. In the case of biaxial stretching, the axis having the larger refractive index among the two types of stretching directions becomes the stretching axis. That is, in the retardation plate prepared by stretching the retardation plate material in the x direction and the y direction, the stretching axis is generated in the direction of the larger refractive index in the x direction and the y direction. For example, the respective refractive index of the stretched x and y directions n _x, and n _y. Further, the refractive index in the thickness direction of the retardation plate is _nz . In this case, for example, if _{_{_{n x> n z> n y}}} , x direction is the direction of stretching axis.

バックライト７は、液晶セル３の各画素を包含する領域に向けて光を照射する。 The backlight 7 irradiates light toward a region including each pixel of the liquid crystal cell 3.

以下、図２から図４を参照して、第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６の軸角の関係について説明する。以下に示す図２以降の各図では、いずれも視認側から見たときの各軸の関係を示している。 Hereinafter, with reference to FIG. 2 to FIG. 4, the relationship between the axial angles of the first polarizing plate 1, the first retardation plate 2, the liquid crystal cell 3, the second retardation plate 5, and the second polarizing plate 6 will be described. . In each figure after FIG. 2 shown below, the relationship of each axis | shaft when all are seen from the visual recognition side is shown.

図２は、第１偏光板１の吸収軸と第１位相差板２の延伸軸との関係を示す説明図である。第１偏光板１の吸収軸１１（図２（ａ）参照。）と、第１位相差板２の延伸軸２１（図２（ｂ）参照。）とがなす角度のうち小さい方の角度をθ_０とした場合（図２（ｃ）参照。）、θ_０は４０〜５０°である。θ_０は４５°であることが好ましい。 FIG. 2 is an explanatory diagram showing the relationship between the absorption axis of the first polarizing plate 1 and the stretching axis of the first retardation plate 2. The smaller one of the angles formed by the absorption axis 11 (see FIG. 2A) of the first polarizing plate 1 and the stretching axis 21 (see FIG. 2B) of the first retardation plate 2 is defined. When θ ₀ is set (see FIG. 2C), θ ₀ is 40 to 50 °. θ ₀ is preferably 45 °.

図３は、液晶セル３のツイスト角、および液晶セル３の配向軸と第１偏光板１の吸収軸、第１位相差板２の延伸軸との軸角を示す説明図である。 FIG. 3 is an explanatory diagram showing the twist angle of the liquid crystal cell 3 and the axis angles of the alignment axis of the liquid crystal cell 3, the absorption axis of the first polarizing plate 1, and the stretching axis of the first retardation plate 2.

図３（ａ）は、液晶セル３のツイスト角を示している。液晶セル３の視認側の配向膜の配向軸１３１と、液晶セル３の反視認側の配向膜の配向軸１３２とのねじれの角度（ツイスト角）は、２３０〜２５０°である。 FIG. 3A shows the twist angle of the liquid crystal cell 3. The twist angle (twist angle) between the alignment axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 and the alignment axis 132 of the alignment film on the non-viewing side of the liquid crystal cell 3 is 230 to 250 °.

図３（ｂ）は、液晶セル３の視認側の配向膜の配向軸１３１を基準軸とした場合における基準軸と、第１偏光板１の吸収軸、第１位相差板２の延伸軸との軸角を示す。既に述べたように、図３では、視認側から見たときの軸角の関係を示している。 FIG. 3B shows the reference axis when the alignment axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 is used as the reference axis, the absorption axis of the first polarizing plate 1, and the stretching axis of the first retardation plate 2. Indicates the axis angle. As already described, FIG. 3 shows the relationship of the shaft angles when viewed from the viewing side.

液晶セル３の視認側の配向膜の配向軸１３１を基準軸として、視認側から見たときの基準軸から第１偏光板１の吸収軸１１までの反時計回りの角度をθ_１とした場合、θ_１は５０〜８５°であり、特に５５〜８０°であることが好ましい。 When the orientation axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 is used as a reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis 11 of the first polarizing plate 1 is θ ₁ , Θ ₁ is 50 to 85 °, and particularly preferably 55 to 80 °.

また、液晶セル３の視認側の配向膜の配向軸１３１を基準軸として、視認側から見たときの基準軸から第１位相差板２の延伸軸２１までの反時計回りの角度をθ_２とした場合、θ_２は１００〜１２５°である。 Further, with the alignment axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis 21 of the first retardation plate 2 is θ _2. If a, theta ₂ is 100-125 °.

図４は、液晶セル３の配向軸と第２位相差板５の延伸軸、第２偏光板６の吸収軸との軸角を示す説明図である。図４（ａ）は、第２位相差板５の延伸軸５１を図示し、図４（ｂ）は、第２偏光板６の吸収軸６１を図示している。図４（ｃ）は、液晶セル３の反視認側の配向膜の配向軸１３２を基準軸とした場合における基準軸と、第２位相差板５の延伸軸５１、第２偏光板６の吸収軸６１との軸角を示す。既に述べたように、図４では、視認側から見たときの各軸の関係を示している。 FIG. 4 is an explanatory diagram showing axial angles between the alignment axis of the liquid crystal cell 3, the stretching axis of the second retardation plate 5, and the absorption axis of the second polarizing plate 6. 4A illustrates the stretching axis 51 of the second retardation plate 5, and FIG. 4B illustrates the absorption axis 61 of the second polarizing plate 6. FIG. 4C shows the reference axis when the alignment axis 132 of the alignment film on the non-viewing side of the liquid crystal cell 3 is used as the reference axis, the stretching axis 51 of the second retardation plate 5, and the absorption of the second polarizing plate 6. An axis angle with the axis 61 is shown. As already described, FIG. 4 shows the relationship between the axes when viewed from the viewing side.

液晶セル３の反視認側の配向膜の配向軸１３２を基準軸として、視認側から見たときの基準軸から第２位相差板５の延伸軸５１までの反時計回りの角度をθ_３とした場合、θ_３は５５〜８５°であり、特に５５〜８０°であることが好ましい。 Using the alignment axis 132 of the alignment film on the counter-viewing side of the liquid crystal cell 3 as a reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis 51 of the second retardation plate 5 is θ ₃ If you, theta ₃ is 55 to 85 °, it is particularly preferably 55 to 80 °.

また、液晶セル３の反視認側の配向膜の配向軸１３２を基準軸として、視認側から見たときの基準軸から第２偏光板６の吸収軸６１までの反時計回りの角度をθ_４とした場合、θ_４は１０〜４０°である。 Further, the orientation axis 132 of the alignment film on the counter-viewing side of the liquid crystal cell 3 is used as a reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis 61 of the second polarizing plate 6 is θ _4. If a, theta ₄ is 10 to 40 °.

θ_０〜θ_４の各角度が上述の範囲の値になるように、第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６は配置される。 The first polarizing plate 1, the first retardation plate 2, the liquid crystal cell 3, the second retardation plate 5, and the second polarizing plate 6 are adjusted so that the angles θ _{0 to} θ ₄ are in the above-described range. Be placed.

次に、視認側から入射し、メタルＢＭ３３（図１参照。）やメタル配線（図示せず。）で反射する光について説明する。視認側から液晶表示素子に入射した光は、第１偏光板１を通過する。このとき、第１偏光板１は、入射した光の偏光状態を、第１偏光板１の偏光軸方向に振動する直線偏光に変化させる。直線偏光となった光は、第１位相差板（３／４波長板）２を通過する。このとき、第１位相差板２は、その光の偏光状態を直線偏光から円偏光に変化させる。 Next, light incident from the viewing side and reflected by the metal BM 33 (see FIG. 1) and metal wiring (not shown) will be described. Light incident on the liquid crystal display element from the viewing side passes through the first polarizing plate 1. At this time, the first polarizing plate 1 changes the polarization state of the incident light to linearly polarized light that vibrates in the polarization axis direction of the first polarizing plate 1. The light that has become linearly polarized light passes through the first retardation plate (3/4 wavelength plate) 2. At this time, the first retardation plate 2 changes the polarization state of the light from linearly polarized light to circularly polarized light.

円偏光となった光は、メタルＢＭ３３やメタル配線で反射し、再び第１位相差板（３／４波長板）２を通過する。このとき、第１位相差板２は、メタルＢＭ３３やメタル配線で反射した光の偏光状態を、円偏光から直線偏光に変化させる。メタルＢＭ３３等での反射後に第１位相差板２を通過して直線偏光になった光の振動方向は、第１偏光板１の偏光軸と直交する方向（すなわち、第１偏光板１の吸収軸の方向）である。従って、メタルＢＭ３３やメタル配線での反射後に第１位相差板２を通過した光は第１偏光板１で吸収され、第１偏光板１を通過しにくくなる。その結果、メタルＢＭ３３やメタル配線で反射した光は観察者に観察されにくくなり、良好な視認性を実現することができる。液晶表示素子の画素を光透過状態にしたときであっても、視認側から入射して金属部分で反射した光は観察者に観察されにくくなるので、良好な視認性が得られる。 The light that has become circularly polarized light is reflected by the metal BM 33 or the metal wiring and passes through the first retardation plate (3/4 wavelength plate) 2 again. At this time, the first retardation plate 2 changes the polarization state of the light reflected by the metal BM 33 or the metal wiring from circularly polarized light to linearly polarized light. The vibration direction of light that has passed through the first phase difference plate 2 and has been linearly polarized after being reflected by the metal BM 33 or the like is a direction orthogonal to the polarization axis of the first polarizing plate 1 (that is, absorption of the first polarizing plate 1). Axis direction). Therefore, the light that has passed through the first retardation plate 2 after being reflected by the metal BM 33 or the metal wiring is absorbed by the first polarizing plate 1 and is difficult to pass through the first polarizing plate 1. As a result, the light reflected by the metal BM 33 and the metal wiring is not easily observed by the observer, and good visibility can be realized. Even when the pixels of the liquid crystal display element are in a light-transmitting state, light that is incident from the viewing side and reflected by the metal portion is less likely to be observed by the observer, so that good visibility can be obtained.

また、１軸延伸の位相差板は角度依存性を有している。例えば４０°傾いた方向から見ると、位相差板の位相差値は１０％程度変化することがある。２軸延伸の位相差板は角度依存性が小さく、斜め方向から視認してもメタルＢＭで反射した光を観察されにくくすることができる。特に、Ｎ_ｚ＝（ｎ_ｘ−ｎ_ｚ）／（ｎ_ｘ−ｎ_ｙ）＝０．４〜０．６の範囲とする２軸延伸の位相差板を第１位相差板２に採用すると、斜め方向からのメタルＢＭの反射光は視認できなくなり、もっとも好ましい。 Moreover, the uniaxially stretched phase difference plate has angle dependency. For example, when viewed from a direction inclined by 40 °, the retardation value of the retardation film may change by about 10%. The biaxially stretched phase difference plate has little angle dependency, and even when viewed from an oblique direction, the light reflected by the metal BM can be hardly observed. In _particular, N _z = the _{_{_{(n x -n z) / (}}} n x -n y) = the phase difference plate of biaxial stretching employed in the first phase difference plate 2 in a range of 0.4 to 0.6, The reflected light of the metal BM from the oblique direction cannot be visually recognized, and is most preferable.

また、本発明では、上述のような第１偏光板１と、第１位相差板２と、液晶セル３と、第２位相差板５と、第２偏光板６とを備え、θ_０〜θ_４の各角度が上述の範囲の値になるように各部材を配置することによって、反射した光を観察されにくくすることができ、良好な白色および黒色の２色表示を実現することができる。 In the present invention, the first polarizing plate 1, the first retardation plate 2, the liquid crystal cell 3, the second retardation plate 5, and the second polarizing plate 6 as described above are provided, and θ ₀ to By disposing each member so that each angle of θ ₄ falls within the above range, it is possible to make it difficult to observe the reflected light, and it is possible to realize a good two-color display of white and black. .

また、第２位相差板５および第２偏光板６を以下のように配置することがより好ましい。図５は、より好ましい第２位相差板５の延伸軸５１と第２偏光板６の吸収軸６１との軸角を示す説明図である。第２位相差板５の延伸軸５１と第２偏光板６の吸収軸６１とがなす角度のうち小さい方の角度をθ_５とした場合、θ_５は３５〜５５°であることが好ましい。さらに、θ_５が４０〜５０°であることがより好ましい。θ_０〜θ_４の各角度が上述の範囲の値になるようにし、さらにθ_５が３５〜５５°（より好ましくは４０〜５０°）となるように、第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６を配置すれば、液晶表示素子の画素を光透過状態にしたときの視認性をより向上させることができる。 Moreover, it is more preferable to arrange the second retardation plate 5 and the second polarizing plate 6 as follows. FIG. 5 is an explanatory diagram showing the axial angle between the stretching axis 51 of the second retardation plate 5 and the absorption axis 61 of the second polarizing plate 6. If the theta ₅ a smaller angle of the angles and the absorption axis 61 formed by the stretching axis 51 of the second retardation plate 5 second polarizing plate 6, theta ₅ is preferably 35 to 55 °. Furthermore, θ ₅ is more preferably 40 to 50 °. The first polarizing plate 1 and the first position are set so that each angle of θ _{0 to} θ ₄ is in the above range, and further, θ ₅ is 35 to 55 ° (more preferably 40 to 50 °). If the phase difference plate 2, the liquid crystal cell 3, the second phase difference plate 5, and the second polarizing plate 6 are disposed, the visibility when the pixels of the liquid crystal display element are in a light transmission state can be further improved.

上記の実施の形態では、第１偏光板１の吸収軸および第２偏光板６の吸収軸を用いて各軸の関係（換言すれば、第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６の配置）を定めていた。第１偏光板１の吸収軸および第２偏光板６の吸収軸を偏光軸に置き換えて、各軸の関係を上記の実施の形態と同様に定めてもよい。以下、図６から図９を参照して、第１偏光板１の偏光軸および第２偏光板６の偏光軸を用いて各軸の関係を定める場合について説明する。ただし、第１偏光板１の吸収軸および第２偏光板６の吸収軸を用いて各軸の関係を定める場合と同じ事項については説明を省略する。 In the above embodiment, the relationship between the axes using the absorption axis of the first polarizing plate 1 and the absorption axis of the second polarizing plate 6 (in other words, the first polarizing plate 1, the first retardation plate 2, the liquid crystal). Cell 3, second retardation plate 5, and second polarizing plate 6). The absorption axis of the first polarizing plate 1 and the absorption axis of the second polarizing plate 6 may be replaced with polarization axes, and the relationship between the axes may be determined in the same manner as in the above embodiment. Hereinafter, with reference to FIG. 6 to FIG. 9, a case will be described in which the relationship between the respective axes is determined using the polarization axis of the first polarizing plate 1 and the polarization axis of the second polarizing plate 6. However, the description of the same matters as when the relationship between the axes is determined using the absorption axis of the first polarizing plate 1 and the absorption axis of the second polarizing plate 6 will be omitted.

図６は、第１偏光板１の偏光軸と第１位相差板２の延伸軸との関係を示す説明図である。第１偏光板１の偏光軸１５（図６（ａ）参照。）と、第１位相差板２の延伸軸２１（図６（ｂ）参照。）とがなす角度のうち小さい方の角度をθ_０とした場合（図６（ｃ）参照。）、θ_０は４０〜５０°である。θ_０は４５°であることが好ましい。 FIG. 6 is an explanatory diagram showing the relationship between the polarization axis of the first polarizing plate 1 and the stretching axis of the first retardation plate 2. The smaller one of the angles formed by the polarization axis 15 (see FIG. 6A) of the first polarizing plate 1 and the stretching axis 21 (see FIG. 6B) of the first retardation plate 2 is defined. When θ ₀ is set (see FIG. 6C), θ ₀ is 40 to 50 °. θ ₀ is preferably 45 °.

図７は、液晶セル３の視認側の配向膜の配向軸１３１を基準軸とした場合における基準軸と、第１偏光板１の偏光軸、第１位相差板２の延伸軸との軸角を示す説明図である。 FIG. 7 shows an axial angle between the reference axis when the alignment axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 is used as the reference axis, the polarization axis of the first polarizing plate 1, and the stretching axis of the first retardation plate 2. It is explanatory drawing which shows.

液晶セル３の視認側の配向膜の配向軸１３１を基準軸として、視認側から見たときの基準軸から第１偏光板１の偏光軸１５までの反時計回りの角度をθ_１とした場合、θ_１は５０〜８５°であり、特に５５〜８０°であることが好ましい。 When the orientation axis 131 of the alignment film on the viewing side of the liquid crystal cell 3 is the reference axis, and the counterclockwise angle from the reference axis to the polarization axis 15 of the first polarizing plate 1 when viewed from the viewing side is θ ₁ , Θ ₁ is 50 to 85 °, and particularly preferably 55 to 80 °.

図８は、液晶セル３の反視認側の配向膜の配向軸１３２を基準軸とした場合における基準軸と、第２位相差板５の延伸軸５１、第２偏光板６の偏光軸６５との軸角を示す説明図である。 FIG. 8 shows the reference axis when the alignment axis 132 of the alignment film on the non-viewing side of the liquid crystal cell 3 is used as the reference axis, the stretching axis 51 of the second retardation plate 5, and the polarization axis 65 of the second polarizing plate 6. It is explanatory drawing which shows the shaft angle.

また、液晶セル３の反視認側の配向膜の配向軸１３２を基準軸として、視認側から見たときの基準軸から第２偏光板６の偏光軸６５までの反時計回りの角度をθ_４とした場合、θ_４は１０〜４０°である。 Further, with the alignment axis 132 of the alignment film on the counter-viewing side of the liquid crystal cell 3 as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the polarization axis 65 of the second polarizing plate 6 is θ _4. If a, theta ₄ is 10 to 40 °.

第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６は、θ_０〜θ_４の各角度が上述の範囲の値になるように配置される。このように各部材を配置した場合であっても、反射した光を観察されにくくすることができ、良好な白色および黒色の２色表示を実現することができる。 The first polarizing plate 1, the first retardation plate 2, the liquid crystal cell 3, the second retardation plate 5, and the second polarizing plate 6 are set so that each angle of θ _{0 to} θ ₄ is in the above range. Be placed. Even when each member is arranged in this manner, the reflected light can be made difficult to be observed, and a good two-color display of white and black can be realized.

また、第１偏光板１の表面にＡＲ処理（アンチリフレクション処理）を施すことで、表面反射を防止することができる。よって、さらに視認性を向上させることができる。 Moreover, surface reflection can be prevented by performing AR treatment (anti-reflection treatment) on the surface of the first polarizing plate 1. Therefore, visibility can be further improved.

図９は、より好ましい第２位相差板５の延伸軸５１と第２偏光板６の偏光軸６５との軸角を示す説明図である。第２位相差板５の延伸軸５１と第２偏光板６の偏光軸６５とがなす角度のうち小さい方の角度をθ_５とした場合、θ_５は３５〜５５°であることが好ましい。さらに、θ_５が４０〜５０°であることがより好ましい。θ_０〜θ_４の各角度が上述の範囲の値になるようにし、さらにθ_５が３５〜５５°（より好ましくは４０〜５０°）となるように、第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６を配置すれば、液晶表示素子の画素を光透過状態にしたときの視認性をより向上させることができる。 FIG. 9 is an explanatory diagram showing the axial angle between the stretching axis 51 of the second retardation plate 5 and the polarization axis 65 of the second polarizing plate 6. When the smaller angle among the angles formed by the stretching axis 51 of the second retardation plate 5 and the polarization axis 65 of the second polarizing plate 6 is θ ₅ , θ ₅ is preferably 35 to 55 °. Furthermore, θ ₅ is more preferably 40 to 50 °. The first polarizing plate 1 and the first position are set so that each angle of θ _{0 to} θ ₄ is in the above range, and further, θ ₅ is 35 to 55 ° (more preferably 40 to 50 °). If the phase difference plate 2, the liquid crystal cell 3, the second phase difference plate 5, and the second polarizing plate 6 are disposed, the visibility when the pixels of the liquid crystal display element are in a light transmission state can be further improved.

以下に示すように、ＳＴＮ型の液晶セル３を調整した。液晶層のツイスト角が２４０°となり、左ツイストとなるように調整した。また、液晶の転移温度Ｔ_ｃ（Clearing Point）が１０５°となり、液晶層の位相差値（Δｎ_ＬＣ・ｄ_ＬＣ）が８３０ｎｍとなるように調整した。なお、転移温度Ｔ_ｃは、液晶状体から等方性液体への転移温度である。 As shown below, an STN type liquid crystal cell 3 was prepared. The liquid crystal layer was adjusted to have a twist angle of 240 ° and a left twist. In addition, the transition temperature T _c (Clearing Point) of the liquid crystal was adjusted to 105 °, and the retardation value (Δn _LC · d _LC ) of the liquid crystal layer was adjusted to 830 nm. The transition temperature _Tc is the transition temperature from the liquid crystal to the isotropic liquid.

また、第１位相差板２として、位相差値（Δｎ_Ｆ１・ｄ_Ｆ１）が４４５ｎｍである位相差板を用いた。第２位相差板５として、位相差値（Δｎ_Ｆ２・ｄ_Ｆ２）が４４５ｎｍである位相差板を用いた。また、第１偏光板１および第２偏光板６として、日東電工社製ＮＰＦ−ＥＧ１４２５ＤＵを用いた。 Further, as the first retardation plate 2, a retardation plate having a retardation value (Δn _F1 · d _F1 ) of 445 nm was used. As the second retardation plate 5, a retardation plate having a retardation value (Δn _F2 · d _F2 ) of 445 nm was used. Further, NPF-EG1425DU manufactured by Nitto Denko Corporation was used as the first polarizing plate 1 and the second polarizing plate 6.

θ_０＝４５°、θ_１＝７０°、θ_２＝１１５°、θ_３＝７０°、θ_４＝２５°、θ_５＝４５°となるように第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６を配置して、液晶表示素子を作成した。なお、実施例１におけるθ_０〜θ_５は、第１偏光板の吸収軸および第２偏光板の吸収軸を用いて定めた場合の軸角である（図２、図３、図４、図５参照。）。 The first polarizing plate 1 and the first retardation plate so that θ ₀ = 45 °, θ ₁ = 70 °, θ ₂ = 115 °, θ ₃ = 70 °, θ ₄ = 25 °, θ ₅ = 45 °. 2, the liquid crystal cell 3, the 2nd phase difference plate 5, and the 2nd polarizing plate 6 were arrange | positioned, and the liquid crystal display element was created. In addition, θ _{0 to} θ ₅ in Example 1 are axial angles determined using the absorption axis of the first polarizing plate and the absorption axis of the second polarizing plate (FIGS. 2, 3, 4, and 5). 5).

この液晶表示素子を、デューティ比を１／６５として駆動したところ、電圧オフ時に黒色表示とし、電圧オン時に白色表示とするネガ表示を行うことができた。 When this liquid crystal display element was driven at a duty ratio of 1/65, it was possible to perform a negative display in which a black display was made when the voltage was turned off and a white display was made when the voltage was turned on.

［比較例］以下に示すように、ＳＴＮ型の液晶セル３を調整した。液晶層のツイスト角が２４０°となり、左ツイストとなるように調整した。また、液晶の転移温度Ｔ_ｃ（Clearing Point）が１０５°となり、液晶層の位相差値（Δｎ_ＬＣ・ｄ_ＬＣ）が８３０ｎｍとなるように調整した。 [Comparative Example] An STN type liquid crystal cell 3 was prepared as described below. The liquid crystal layer was adjusted to have a twist angle of 240 ° and a left twist. In addition, the transition temperature T _c (Clearing Point) of the liquid crystal was adjusted to 105 °, and the retardation value (Δn _LC · d _LC ) of the liquid crystal layer was adjusted to 830 nm.

また、第１位相差板２として、位相差値（Δｎ_Ｆ１・ｄ_Ｆ１）が４４５ｎｍである位相差板を用いた。第２位相差板５として、位相差値（Δｎ_Ｆ２・ｄ_Ｆ２）が４３５ｎｍである位相差板を用いた。また、第１偏光板１および第２偏光板６は、実施例１と同様の日東電工社製ＮＰＦ−ＥＧ１４２５ＤＵを用いた。 Further, as the first retardation plate 2, a retardation plate having a retardation value (Δn _F1 · d _F1 ) of 445 nm was used. As the second retardation plate 5, a retardation plate having a retardation value (Δn _F2 · d _F2 ) of 435 nm was used. The first polarizing plate 1 and the second polarizing plate 6 were the same NPF-EG1425DU manufactured by Nitto Denko Corporation as in Example 1.

θ_０＝６０°、θ_１＝４０°、θ_２＝１００°、θ_３＝８０°、θ_４＝５０°、θ_５＝３０°となるように第１偏光板１、第１位相差板２、液晶セル３、第２位相差板５、および第２偏光板６を配置して、液晶表示素子を作成した。なお、比較例におけるθ_０〜θ_５は、第１偏光板の吸収軸および第２偏光板の吸収軸を用いて定めた場合の軸角である（図２、図３、図４、図５参照。）。 The first polarizing plate 1 and the first retardation plate so that θ ₀ = 60 °, θ ₁ = 40 °, θ ₂ = 100 °, θ ₃ = 80 °, θ ₄ = 50 °, θ ₅ = 30 °. 2, the liquid crystal cell 3, the 2nd phase difference plate 5, and the 2nd polarizing plate 6 were arrange | positioned, and the liquid crystal display element was created. In the comparative example, θ _{0 to} θ ₅ are axial angles determined using the absorption axis of the first polarizing plate and the absorption axis of the second polarizing plate (FIGS. 2, 3, 4, and 5). reference.).

また、メタルＢＭとして、反射率が約４０％のクロム（Ｃｒ）を用いた。このときの液晶セルの反射率は下表のようになった。これには液晶セル表面（第１偏光板表面）の反射率約４％が含まれている。よって、メタルＢＭ表面での概算反射率も下表に示す。 Further, chromium (Cr) having a reflectance of about 40% was used as the metal BM. The reflectivity of the liquid crystal cell at this time is as shown in the table below. This includes a reflectance of about 4% on the surface of the liquid crystal cell (the surface of the first polarizing plate). Therefore, the approximate reflectance on the metal BM surface is also shown in the table below.

実施例１の液晶表示素子では、液晶表示素子に外光が入射してその光がメタル表面で反射したときに再び液晶表示素子の外部に通過する反射光を、比較例の液晶表示素子の１／２〜１／３以下にすることができた。そして、実施例１の液晶表示素子では、画素を光透過状態にしたときに、比較例の液晶表示素子よりも良好な視認性が得られた。 In the liquid crystal display element of the first embodiment, when external light is incident on the liquid crystal display element and the light is reflected on the metal surface, the reflected light that passes again outside the liquid crystal display element is 1 of the liquid crystal display element of the comparative example. / 2 to 1/3 or less. And in the liquid crystal display element of Example 1, the visibility better than the liquid crystal display element of the comparative example was acquired when the pixel was made into the light-transmissive state.

また、外光を入射させないで、コントラスト比を調べた結果、実施例１が９３：１、比較例が９５：１とほぼ同等の良好なコントラスト比を得た。 In addition, as a result of examining the contrast ratio without incident external light, a good contrast ratio almost equal to 93: 1 in Example 1 and 95: 1 in Comparative Example was obtained.

第１位相差板２を２軸延伸の位相差板に変えた以外は実施例１と同様に液晶表示素子を作成した。 A liquid crystal display element was prepared in the same manner as in Example 1 except that the first retardation plate 2 was changed to a biaxially stretched retardation plate.

第１位相差板２として、Ｎ_ｚ値が０．５の位相差板を用いて点灯状態を観察すると、電圧オフ時に黒色表示となり、電圧オン時に白色表示となるネガ表示を行うことができた。このときのコントラスト比は実施例１とほぼ同等の良好な値で、視認性も良好であった。また、位相差値の角度変化が小さい位相差板を用いたので、メタルＢＭ表面の反射の角度依存性も小さくなり、液晶表示素子を様々な方向から観察しても、反射光を観察できなかった。 When the lighting state was observed using a phase difference plate having an _Nz value of 0.5 as the first phase difference plate 2, a negative display was obtained in which black display was obtained when the voltage was turned off and white display was obtained when the voltage was turned on. . The contrast ratio at this time was a good value almost equivalent to that of Example 1, and the visibility was also good. In addition, since a phase difference plate having a small angle change of the phase difference value is used, the angle dependency of reflection on the surface of the metal BM is also reduced, and the reflected light cannot be observed even when the liquid crystal display element is observed from various directions. It was.

本発明は、ＳＴＮ型の液晶セルを含む液晶表示素子として好適に適用可能である。 The present invention can be suitably applied as a liquid crystal display element including an STN type liquid crystal cell.

本発明の液晶表示素子を示す模式的断面図。1 is a schematic cross-sectional view showing a liquid crystal display element of the present invention. 第１偏光板の吸収軸と第１位相差板の延伸軸との関係を示す説明図。Explanatory drawing which shows the relationship between the absorption axis of a 1st polarizing plate, and the extending | stretching axis | shaft of a 1st phase difference plate. 液晶セルのツイスト角、および液晶セルの配向軸と第１偏光板の吸収軸、第１位相差板の延伸軸との軸角を示す説明図。Explanatory drawing which shows the twist angle of a liquid crystal cell, and the axial angle of the orientation axis | shaft of a liquid crystal cell, the absorption axis of a 1st polarizing plate, and the extending | stretching axis | shaft of a 1st phase difference plate. 液晶セルの配向軸と第２位相差板の延伸軸、第２偏光板の吸収軸との軸角を示す説明図。Explanatory drawing which shows the axial angle with the orientation axis | shaft of a liquid crystal cell, the extending | stretching axis | shaft of a 2nd phase difference plate, and the absorption axis of a 2nd polarizing plate. より好ましい第２位相差板の延伸軸と第２偏光板の吸収軸との軸角を示す説明図。Explanatory drawing which shows the axial angle of the extending | stretching axis | shaft of a more preferable 2nd phase difference plate, and the absorption axis of a 2nd polarizing plate. 第１偏光板の偏光軸と第１位相差板の延伸軸との関係を示す説明図。Explanatory drawing which shows the relationship between the polarizing axis of a 1st polarizing plate, and the extending | stretching axis | shaft of a 1st phase difference plate. 液晶セルの視認側の配向膜の配向軸を基準軸とした場合における基準軸と、第１偏光板の偏光軸、第１位相差板の延伸軸との軸角を示す説明図。Explanatory drawing which shows the axis angle of the reference axis in the case of making the alignment axis of the alignment film by the side of visual recognition of a liquid crystal cell into a reference axis, the polarizing axis of a 1st polarizing plate, and the extending | stretching axis of a 1st phase difference plate. 液晶セルの反視認側の配向膜の配向軸を基準軸とした場合における基準軸と、第２位相差板の延伸軸、第２偏光板の偏光軸との軸角を示す説明図。Explanatory drawing which shows the axial angle of the reference | standard axis | shaft at the time of setting the orientation axis | shaft of the alignment film of the non-viewing side of a liquid crystal cell as a reference axis, the extending | stretching axis | shaft of a 2nd phase difference plate, and the polarizing axis of a 2nd polarizing plate. より好ましい第２位相差板の延伸軸と第２偏光板の偏光軸との軸角を示す説明図。Explanatory drawing which shows the axial angle of the extending | stretching axis | shaft of a more preferable 2nd phase difference plate, and the polarizing axis of a 2nd polarizing plate.

Explanation of symbols

１第１偏光板
２第１位相差板
３液晶セル
５第２位相差板
６第２偏光板
７バックライト
３３メタルＢＭ DESCRIPTION OF SYMBOLS 1 1st polarizing plate 2 1st phase difference plate 3 Liquid crystal cell 5 2nd phase difference plate 6 2nd polarizing plate 7 Backlight 33 Metal BM

Claims

A liquid crystal display comprising an STN type liquid crystal cell having a liquid crystal layer between a transparent substrate provided with an alignment film between a first polarizing plate disposed on the viewing side and a second polarizing plate disposed on the non-viewing side. An element,
A first retardation plate having a retardation value of 420 to 480 nm is provided between the first polarizing plate and the STN type liquid crystal cell,
A second retardation plate having a retardation value of 415 to 480 nm is provided between the second polarizing plate and the STN type liquid crystal cell,
The STN type liquid crystal cell has a black matrix using metal,
The twist angle of the STN type liquid crystal cell is 230 to 250 °,
The retardation value of the liquid crystal layer of the STN type liquid crystal cell is 780 to 920 nm,
When the smaller angle among the angles formed by the absorption axis of the first polarizing plate and the stretching axis of the first retardation plate is θ ₀ , θ ₀ is 40 to 50 °,
When the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell is the reference axis and the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis of the first polarizing plate is θ ₁ , θ ₁ is 50 to 85 °,
When the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell is the reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis of the first retardation plate is θ ₂ , Θ ₂ is 100 to 125 °,
With the orientation axis of the alignment film on the counter-viewing side of the STN type liquid crystal cell as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis of the second retardation plate is θ ₃ . If, θ ₃ is 55~85 °,
When the orientation axis of the alignment film on the counter-viewing side of the STN type liquid crystal cell is the reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis of the second polarizing plate is θ ₄ a liquid crystal display element characterized by theta ₄ is 10 to 40 °.

If the angle of the smaller one of angles formed stretching axis of the second retardation plate and the absorption axis of the second polarizing plate has a θ _{_5,} θ ₅ is a liquid crystal display according to claim 1 which is 35 to 55 ° element.

A liquid crystal display comprising an STN type liquid crystal cell having a liquid crystal layer between a transparent substrate provided with an alignment film between a first polarizing plate disposed on the viewing side and a second polarizing plate disposed on the non-viewing side. An element,
A first retardation plate having a retardation value of 420 to 480 nm is provided between the first polarizing plate and the STN type liquid crystal cell,
A second retardation plate having a retardation value of 415 to 480 nm is provided between the second polarizing plate and the STN type liquid crystal cell,
The STN type liquid crystal cell has a black matrix using metal,
The twist angle of the STN type liquid crystal cell is 230 to 250 °,
The retardation value of the liquid crystal layer of the STN type liquid crystal cell is 780 to 920 nm,
When the smaller angle formed by the polarization axis of the first polarizing plate and the stretching axis of the first retardation plate is θ ₀ , θ ₀ is 40 to 50 °,
When the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell is the reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the polarization axis of the first polarizing plate is θ ₁ , θ ₁ is 50 to 85 °,
When the orientation axis of the alignment film on the viewing side of the STN type liquid crystal cell is the reference axis, and the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis of the first retardation plate is θ ₂ , Θ ₂ is 100 to 125 °,
With the orientation axis of the alignment film on the counter-viewing side of the STN type liquid crystal cell as the reference axis, the counterclockwise angle from the reference axis when viewed from the viewing side to the stretching axis of the second retardation plate is θ ₃ . If, θ ₃ is 55~85 °,
When the orientation axis of the alignment film on the counter-viewing side of the STN type liquid crystal cell is the reference axis and the counterclockwise angle from the reference axis when viewed from the viewing side to the polarization axis of the second polarizing plate is θ ₄ a liquid crystal display element characterized by theta ₄ is 10 to 40 °.

If the angle of the smaller one of angles formed stretching axis of the second retardation plate and the polarization axis of the second polarizing plate has a θ _{_5,} θ ₅ is a liquid crystal display according to claim 3 which is 35 to 55 ° element.