JP3265802B2 - Liquid crystal display - Google Patents

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、低消費電力のＩＣで構
成され明るくかつ視角特性が良好で低コストの薄膜トラ
ンジスタ型液晶表示装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-cost thin-film transistor liquid crystal display device which is composed of an IC with low power consumption, is bright, has good viewing angle characteristics and is low in cost.

【０００２】[0002]

【従来の技術】従来の薄膜トランジスタ型液晶表示装置
では、液晶層を駆動する電極としては２枚の基板界面上
に形成し相対向させた透明電極を用いていた。これは、
液晶に印加する電界の方向を基板界面にほぼ垂直な方向
とすることで動作する、ツイステッドネマチック表示方
式に代表される表示方式を採用していることによる。一
方、液晶に印加する電界の方向を基板界面にほぼ平行な
方向とする方式として、櫛歯電極対を用いた方式が、例
えば特公昭63−21907 号により提案されているが、表示
装置としては実用化されていない。2. Description of the Related Art In a conventional thin film transistor type liquid crystal display device, transparent electrodes formed on the interface between two substrates and opposed to each other are used as electrodes for driving a liquid crystal layer. this is,
This is because a display method typified by a twisted nematic display method, which operates by setting the direction of an electric field applied to the liquid crystal to a direction substantially perpendicular to the substrate interface, is employed. On the other hand, as a method of making the direction of the electric field applied to the liquid crystal substantially parallel to the substrate interface, a method using a pair of comb electrodes has been proposed, for example, in Japanese Patent Publication No. 63-21907, but as a display device. Not practical.

【０００３】[0003]

【発明が解決しようとする課題】前記の従来技術の表示
装置においては、視角方向を変化させた際の輝度変化が
著しく、特に中間調表示を行った場合、視角方向により
階調レベルが反転してしまうなど、実用上問題であっ
た。これに対し、櫛歯電極対を用いて液晶に印加する電
界の方向を基板界面にほぼ平行な方向とする方式を採用
すると、明るさの視角依存性がほぼなくなることが明ら
かにされている(参照、R. Kiefer, B. Weber, F. Winds
cheid and G. Baur, Proceedings of the Twelfth Inte
rnational Display Research Conference(Japan Displa
y, 92')pp.547−550）。しかしながら、この発表におい
ては薄膜トランジスタの構造とこの方式に適した駆動方
法についての記述はない。また、ここで示された構成に
おいては、十分な光透過率とコントラスト比を保つには
例えば８ボルト以上の高い電圧を印加する必要があり、
製造コストや消費電力が高い高耐圧の駆動ＩＣを用いな
くてはならない。加えて、電極間ギャップが僅かに１０
μｍと、通常の液晶表示装置の画素ピッチに比べて極め
て狭く、パネルの光透過率を引上げ明るさを高めるため
に必須である高開口率の確保が非常に困難となってい
る。一方で高開口率確保のために電極間ギャップを広げ
ると、電極間の電界強度が低下し、十分な光透過率を保
つのに要する駆動電圧がますます高くなってしまい、あ
い路となっていた。In the display device of the prior art described above, the luminance change when the viewing angle direction is changed is remarkable. In particular, when a halftone display is performed, the gradation level is inverted depending on the viewing angle direction. This was a practical problem. On the other hand, it has been clarified that the viewing angle dependency of the brightness is almost eliminated by using a method in which the direction of the electric field applied to the liquid crystal using the pair of comb electrodes is made substantially parallel to the substrate interface. See, R. Kiefer, B. Weber, F. Winds
cheid and G. Baur, Proceedings of the Twelfth Inte
rnational Display Research Conference (Japan Displa
y, 92 ') pp. 547-550). However, this publication does not describe the structure of a thin film transistor and a driving method suitable for this method. Further, in the configuration shown here, it is necessary to apply a high voltage of, for example, 8 volts or more to maintain a sufficient light transmittance and contrast ratio.
It is necessary to use a high-withstand-voltage drive IC with high manufacturing cost and high power consumption. In addition, the gap between electrodes is only 10
μm, which is extremely narrower than the pixel pitch of an ordinary liquid crystal display device, and it is extremely difficult to secure a high aperture ratio which is essential for increasing the light transmittance of the panel and increasing the brightness. On the other hand, if the gap between the electrodes is widened to ensure a high aperture ratio, the electric field strength between the electrodes will decrease, and the driving voltage required to maintain a sufficient light transmittance will increase further, resulting in an obstacle. Was.

【０００４】一方、特公昭63−21907 号には相互に咬合
する櫛歯電極対を薄膜トランジスタと接続した構造が提
案されているが、ここでは櫛歯電極を１画素内に１７本
も導入しており、十分な画素開口率（例えば３０％以
上）を維持するには櫛歯電極の電極幅を１〜２μｍ程度
以下と極めて狭くする必要がある。開口率を実用レベル
まで拡大しかつ高電界を印加するには極めて狭い幅の電
極をこのように多数本導入し、対の電極間のギャップを
できるだけ狭くすることが必要である。しかしながら、
大型基板全面にわたってそのような細線を均一にかつ断
線がないように形成することは極めて困難である。即
ち、上記の従来技術では、低駆動電圧，高画素開口率と
製造歩留まりがトレ−ドオフの関係となり、明るい画像
を有する液晶表示装置を低コストで提供することは困難
であった。On the other hand, Japanese Patent Publication No. 63-21907 proposes a structure in which a pair of interdigitated comb-teeth electrodes is connected to a thin-film transistor. Here, as many as seventeen comb-teeth electrodes are introduced in one pixel. Therefore, in order to maintain a sufficient pixel aperture ratio (for example, 30% or more), it is necessary to extremely narrow the width of the comb-teeth electrode to about 1 to 2 μm or less. In order to increase the aperture ratio to a practical level and to apply a high electric field, it is necessary to introduce a large number of electrodes having an extremely narrow width and to make the gap between the pair of electrodes as narrow as possible. However,
It is extremely difficult to form such fine lines uniformly and without disconnection over the entire surface of a large substrate. That is, in the above-mentioned prior art, a low drive voltage, a high pixel aperture ratio and a manufacturing yield have a trade-off relationship, and it has been difficult to provide a liquid crystal display device having a bright image at low cost.

【０００５】本発明はこれらの課題を同時に解決するも
ので、少ない本数の電極により、かつ電極間ギャップを
さほど狭めずとも実用上十分に低い耐圧のＩＣによって
駆動可能な高画素開口率薄膜トランジスタ型液晶表示装
置を提供することにある。The present invention solves these problems at the same time. A high pixel aperture ratio thin film transistor type liquid crystal which can be driven by an IC having a practically sufficiently low breakdown voltage with a small number of electrodes and without significantly reducing the gap between the electrodes. A display device is provided.

【０００６】[0006]

【課題を解決するための手段】前記課題を解決し、上記
目的を達成するために本発明では以下の手段を用いる。
少なくとも一方が透明な一対の基板，該基板間に挾持さ
れ、配向した誘電率異方性と屈折率異方性とを有する液
晶組成物層，偏光手段，マトリクス状に配置された複数
の画素，各画素ごとに備えられ、画素電極，信号配線電
極及び走査配線電極に接続された薄膜トランジスタ素
子，共通電極，前記画素電極と共通電極の間に電圧信号
波形を印加する手段とを有する液晶表示装置において、 〔手段１〕前記画素電極と前記共通電極は、電圧信号波
形を印加する手段により前記画素電極と前記共通電極と
の間でかつ、基板面にほぼ平行に電界を印加するように
配置され、前記液晶組成物層の配向状態及び前記偏光手
段の構成は、前記画素電極と前記共通電極間に印加され
る電圧Ｖ_LCがほぼゼロにおいて明るさがほぼゼロでかつ
電圧Ｖ_LCをゼロから徐々に増大させるに従い実質的に明
るさが変化しない電圧領域をへた後に明るさが増大す
る、あるいは電圧Ｖ_LCをゼロから徐々に増大させるに従
い明るさが減少し最小値をとるように設定され、前記信
号配線電極および前記共通電極のそれぞれには走査配線
電極に印加する走査信号波形Ｖ_S に同期をとった電圧波
形Ｖ_D，Ｖ_Cが印加され、前記信号配線電極および前記共
通電極に印加される電圧波形Ｖ_D，Ｖ_Cは前記画素に印加
される実効電圧Ｖ_LCが前記共通電極からの電圧波形の振
幅Ｖ_C がゼロの場合に比べて高くなるように定められ、
かつ前記信号配線電極に印加する電圧の波高値を画像情
報に従い変化させることで、前記画素に印加される実効
電圧Ｖ_LCが明るさが最小となる電圧Ｖ_OFF 近傍とそれよ
り明るい状態となる電圧Ｖ_ONとの間で変化するように定
めて駆動されることを特徴とする液晶表示装置。Means for Solving the Problems In order to solve the above problems and achieve the above object, the present invention uses the following means.
At least one of a pair of transparent substrates, a liquid crystal composition layer sandwiched between the substrates and having oriented dielectric anisotropy and refractive index anisotropy, polarizing means, a plurality of pixels arranged in a matrix, A liquid crystal display device provided for each pixel, comprising: a thin film transistor element connected to a pixel electrode, a signal wiring electrode and a scanning wiring electrode; a common electrode; and means for applying a voltage signal waveform between the pixel electrode and the common electrode. [Means 1] the pixel electrode and the common electrode are arranged so as to apply an electric field between the pixel electrode and the common electrode by means for applying a voltage signal waveform and substantially parallel to a substrate surface; The alignment state of the liquid crystal composition layer and the configuration of the polarizing means are such that the brightness is substantially zero when the voltage _VLC applied between the pixel electrode and the common electrode is substantially zero, and the voltage _VLC is changed from zero. It is set so that the brightness increases after going through a voltage region where the brightness does not substantially change as the voltage _VLC is gradually increased, or the brightness decreases and takes the minimum value as the voltage _VLC is gradually increased from zero. Voltage waveforms V _D and V _C synchronized with the scanning signal waveform V _S applied to the scanning wiring electrode are applied to the signal wiring electrode and the common electrode, respectively, and are applied to the signal wiring electrode and the common electrode. The voltage waveforms V _D and V _C are determined so that the effective voltage V _LC applied to the pixel is higher than when the amplitude V _C of the voltage waveform from the common electrode is zero,
Further, by changing the peak value of the voltage applied to the signal wiring electrode in accordance with the image information, the effective voltage _VLC applied to the pixel is in the vicinity of the voltage V _OFF where the brightness is minimum, and the voltage at which the state becomes brighter. A liquid crystal display device characterized by being driven so as to change between V _ON and V _ON .

【０００７】手段１によれば少ない本数の電極により、
電極間ギャップをさほど狭めずにも実用上十分に低い耐
圧のＩＣによって駆動可能な広視角薄膜トランジスタ型
液晶表示装置を提供することが可能となる。低い耐圧の
ＩＣの使用は同時に低消費電力化をもたらす。[0007] According to the means 1, by using a small number of electrodes,
It is possible to provide a wide-viewing-angle thin-film transistor liquid crystal display device that can be driven by an IC having a sufficiently low withstand voltage for practical use without reducing the gap between the electrodes so much. Use of an IC having a low withstand voltage results in low power consumption at the same time.

【０００８】〔手段２〕前記液晶組成物層内の配向に関
して、一方の基板界面上での液晶分子配向方向角度φ
_LC1と他方基板界面上での液晶分子配向方向角度φ_LC2と
が互いに略平行（φ_LC1≒φ_LC2≡φ_LC）であり、かつ前
記液晶組成物層の厚みｄ及び屈折率異方性Δｎの積ｄ・
Δｎが０.２１μｍから０.３６μｍの間であることを特
徴とする手段１に記載の液晶表示装置。[Means 2] With respect to the alignment in the liquid crystal composition layer, the liquid crystal molecule alignment direction angle φ on one substrate interface
_LC1 and the liquid crystal molecule orientation angle φ _LC2 on the other substrate interface are substantially parallel to each other (φ _LC1 ≒ φ _LC2 ≡φ _LC ), and the thickness d of the liquid crystal composition layer and the refractive index anisotropy Δn Product d
2. The liquid crystal display device according to claim 1, wherein Δn is between 0.21 μm and 0.36 μm.

【０００９】手段２によれば液晶表示モードを最適化
し、明るさを最大限引き出すことが可能である。According to the means 2, the liquid crystal display mode can be optimized and the brightness can be maximized.

【００１０】〔手段３〕前記液晶組成物層の誘電率異方
性が正であり、前記界面上の液晶分子の長軸方向と電界
方向とのなす角｜φ_LC｜が４５度を超え９０度未満であ
り、前記偏光手段が前記液晶組成物層を挟む一対の偏光
板であり、該一対の偏光板のうちの一方の偏光板Ａの透
過軸(或いは吸収軸)の角度φ_Pとφ_LCとのなす角｜φ_LC
−φ_P｜が２度以下であることを特徴とする手段２に記
載の液晶表示装置。ただし、−９０度≦φ_LC≦９０度で
ある。[Means 3] The liquid crystal composition layer has a positive dielectric anisotropy, and the angle | φ _LC | between the major axis direction of the liquid crystal molecules on the interface and the electric field direction exceeds 45 degrees and exceeds 90. Degrees, and the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer, and the angles φ _P and φ of the transmission axis (or absorption axis) of one of the polarizing plates A of the pair of polarizing plates. the angle between the _LC | _{φ LC}
3. The liquid crystal display device according to claim 2, wherein -φ _P | is 2 degrees or less. However, -90 degrees ≦ φ _LC ≦ 90 degrees.

【００１１】〔手段４〕前記界面上の液晶分子の長軸方
向と電界方向とのなす角｜φ_LC｜が８５度を超え９０度
未満であり、かつ前記液晶組成物層の厚みｄ及び屈折率
異方性Δｎの積ｄ・Δｎが０.２６μｍから０.３６μｍ
の間であることを特徴とする手段３に記載の液晶表示装
置。[Means 4] The angle | φ _LC | between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is more than 85 degrees and less than 90 degrees, and the thickness d and refraction of the liquid crystal composition layer The product d · Δn of the rate anisotropy Δn is from 0.26 μm to 0.36 μm
3. The liquid crystal display device according to claim 3, wherein

【００１２】〔手段５〕前記液晶組成物層の誘電率異方
性が正であり、前記界面上の液晶分子の長軸方向と電界
方向とのなす角｜φ_LC｜が４５度を超え９０度未満であ
り、前記偏光手段が前記液晶組成物層を挟む一対の偏光
板であり、該一対の偏光板のうちの一方の偏光板の透過
軸（或いは吸収軸）の角度φ_P よりも大きく、かつその
差｜φ_LC−φ_P|が２度以上３０度以下であることを特徴
とする手段２に記載の液晶表示装置。[Means 5] The liquid crystal composition layer has a positive dielectric anisotropy, and the angle | φ _LC | between the major axis direction of the liquid crystal molecules and the electric field direction on the interface exceeds 45 degrees and exceeds 90 degrees. Degrees, and the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer, and is larger than the angle φ _P of the transmission axis (or absorption axis) of one of the pair of polarizing plates. 3. The liquid crystal display device according to claim 2, wherein the difference | φ _LC −φ _P | is not less than 2 degrees and not more than 30 degrees.

【００１３】〔手段６〕前記界面上の液晶分子の長軸方
向と電界方向とのなす角｜φ_LC｜が８０度以上９０度未
満であり、角度差|φ_LC−φ_P｜が２度以上１０度以下で
あることを特徴とする手段５に記載の液晶表示装置。[Means 6] The angle | φ _LC | between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is 80 degrees or more and less than 90 degrees, and the angle difference | φ _LC −φ _P | is 2 degrees. 6. The liquid crystal display device according to claim 5, wherein the angle is not less than 10 degrees.

【００１４】〔手段７〕前記液晶組成物層の誘電率異方
性が負であり、前記界面上の液晶分子の長軸方向と電界
方向とのなす角｜φ_LC｜が０度を超え４５度未満であ
り、前記偏光手段が前記液晶組成物層を挟む一対の偏光
板であり、該一対の偏光板のうちの一方の偏光板の透過
軸（或いは吸収軸）の角度φ_Pとφ_LCとのなす角｜φ_LC
−φ_P｜が２度以下であることを特徴とする手段２に記
載の液晶表示装置。ただし、−９０度≦φ_LC≦９０度で
ある。[Means 7] The dielectric anisotropy of the liquid crystal composition layer is negative, and the angle | φ _LC | between the major axis direction of the liquid crystal molecules and the electric field direction on the interface exceeds 0 degrees and exceeds 45 degrees. Degrees, and the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer, and the angles φ _P and φ _LC of the transmission axis (or absorption axis) of one of the pair of polarizing plates. Angle with the angle | φ _LC
3. The liquid crystal display device according to claim 2, wherein -φ _P | is 2 degrees or less. However, -90 degrees ≦ φ _LC ≦ 90 degrees.

【００１５】〔手段８〕前記界面上の液晶分子の長軸方
向と電界方向とのなす角｜φ_LC｜が０度を超え５度未満
であり、かつ前記液晶組成物層の厚みｄ及び屈折率異方
性Δｎの積ｄ・Δｎが０.２６μｍから０.３６μｍの間
であることを特徴とする手段７に記載の液晶表示装置。[Means 8] The angle | φ _LC | between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is more than 0 degree and less than 5 degrees, and the thickness d and refraction of the liquid crystal composition layer 8. The liquid crystal display device according to claim 7, wherein the product d · Δn of the ratio anisotropy Δn is between 0.26 μm and 0.36 μm.

【００１６】〔手段９〕前記液晶組成物層の誘電率異方
性が負であり、前記界面上の液晶分子の長軸方向と電界
方向とのなす角｜φ_LC｜が０度を超え４５度未満であ
り、前記偏光手段が前記液晶組成物層を挟む一対の偏光
板であり、該一対の偏光板のうちの一方の偏光板の透過
軸（或いは吸収軸）の角度φ_P よりも小さく、かつその
差｜φ_LC−φ_P|が２度以上３０度以下であることを特徴
とする手段２に記載の液晶表示装置。[Means 9] The dielectric anisotropy of the liquid crystal composition layer is negative, and the angle | φ _LC | between the major axis direction of the liquid crystal molecules and the direction of the electric field on the interface exceeds 0 degrees and exceeds 45 degrees. Degrees, and the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer, and is smaller than the angle φ _P of the transmission axis (or absorption axis) of one of the pair of polarizing plates. 3. The liquid crystal display device according to claim 2, wherein the difference | φ _LC −φ _P | is not less than 2 degrees and not more than 30 degrees.

【００１７】〔手段１０〕前記界面上の液晶分子の長軸
方向と電界方向とのなす角｜φ_LC｜が０度を超え１０度
未満であり、前記角度差｜φ_LC−φ_P|が２度以上１０度
以下であることを特徴とする手段９に記載の液晶表示装
置。[Means 10] The angle | φ _LC | between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is more than 0 degree and less than 10 degrees, and the angle difference | φ _LC −φ _P | The liquid crystal display device according to claim 9, wherein the liquid crystal display device has an angle of 2 degrees or more and 10 degrees or less.

【００１８】手段３から手段１０は低い耐圧のＩＣで動
作するように、液晶及び偏光板を最適化する具体策を提
供するものである。Means 3 to 10 provide concrete measures for optimizing the liquid crystal and the polarizing plate so as to operate with an IC having a low withstand voltage.

【００１９】〔手段１１〕前記走査配線電極に少なくと
も３値以上の振幅レベルを有する電圧波形を印加し、走
査選択期間には、薄膜トランジスタ素子の信号配線，画
素電極間の抵抗値を著しく下げるのに十分な高いレベル
を有し、かつもっとも高いレベルのＶ_GHを印加し、非走
査選択期間には、共通配線電極に印加した電圧Ｖ_C の増
減に応じて、異なるレベルの２値以上の電圧（最高値を
Ｖ_GLH，最低値をＶ_GLLと定義する）を印加し、走査配線
電極と共通電極の間の電位差を減じたことを特徴とする
手段１に記載の液晶表示装置。[Means 11] A voltage waveform having an amplitude level of at least three values is applied to the scanning wiring electrode, and during the scanning selection period, the resistance between the signal wiring of the thin film transistor element and the pixel electrode is significantly reduced. It has a sufficient high level, and to apply the highest level V _GH, the non-scanning selection period, in accordance with the increase or decrease of the voltage V _C applied to the common wiring electrode, different levels of 2 or more values of the voltage ( The liquid crystal display device according to claim 1, _wherein a maximum value is defined as V _GLH and a minimum value is defined as _VGLL ) to reduce a potential difference between the scanning wiring electrode and the common electrode.

【００２０】手段１１は手段１及び手段１０全体で生じ
る、基板面に平行に電界を印加する方式を共通電極に電
界を印加する場合の問題である、走査電極と画素電極の
間に生じる寄生容量Ｃ_GSにより発生する飛込み電圧ΔＶ
_GSによる電圧変動の影響を抑制することが可能となる。Means 11 is a method of applying an electric field parallel to the substrate surface, which is a problem when applying an electric field to the common electrode, which is generated in the entire means 1 and means 10, and is a parasitic capacitance generated between the scanning electrode and the pixel electrode. Diving voltage ΔV generated by C _GS
It is possible to suppress the influence of voltage fluctuation due to _GS .

【００２１】[0021]

【作用】先ず初めに、図２により電界方向９に対する界
面近傍での液晶分子長軸（光学軸）方向１０のなす角φ
_LC、偏光板の偏光透過軸１１のなす角φ_P の定義を示
す。偏光板及び液晶界面はそれぞれ上下に一対あるので
必要に応じてφ_P1，φ_P2，φ_LC1，φ_LC2と表記する。
尚、図２は後述する図１の正面図に対応する。First, according to FIG. 2, the angle φ between the liquid crystal molecule major axis (optical axis) direction 10 near the interface and the electric field direction 9 is shown in FIG.
_LC, shows the definition of the angle phi _P polarization transmission axis 11 of the polarizer. Phi _P1 optionally Since the polarizer and the liquid crystal interface is a pair up and down, respectively, φ _P2, φ _LC1, referred to as phi _LC2.
FIG. 2 corresponds to a front view of FIG. 1 described later.

【００２２】次に本発明の作用を図１を用いて説明す
る。Next, the operation of the present invention will be described with reference to FIG.

【００２３】図１（ａ)，(ｂ）は本発明の液晶パネル内
での液晶の動作を示す側断面を、図１（ｃ)，(ｄ）はそ
の正面図を表す。図１には薄膜トランジスタ素子部は省
略され配線電極構造の１部が示されている。また、本発
明の表示装置は複数の画素で構成されるが、ここでは一
画素の中の部分のみを示した。電圧無印加時のセル側断
面を図１（ａ）に、その時の正面図を図１（ｃ）に示
す。透明な一対の基板の内側に線状の電極１，４が形成
され、その上に保護膜兼用の配向制御膜５が塗布及び配
向処理されている。間には液晶組成物が挟持されてい
る。棒状の液晶分子６は、電界無印加時には電極１，４
の長手方向（図１（ｃ）正面図）に対して若干の角度、
即ち４５度≦｜φ_LC｜＜９０度、をもつように配向され
ている。図１，図２では界面上の液晶分子長軸配向（ラ
ビング）方向１０を矢印で示した。上下界面上での液晶
分子配向方向は、望ましい一例として平行、即ちφ_LC1
＝φ_LC2（＝φ_LC）となっている。液晶組成物の誘電異
方性は正を想定している。FIGS. 1A and 1B are side sectional views showing the operation of the liquid crystal in the liquid crystal panel of the present invention, and FIGS. 1C and 1D are front views thereof. FIG. 1 shows a part of the wiring electrode structure without the thin film transistor element part. Although the display device of the present invention includes a plurality of pixels, only a part of one pixel is shown here. FIG. 1A shows a cross section of the cell when no voltage is applied, and FIG. 1C shows a front view at that time. Linear electrodes 1 and 4 are formed inside a pair of transparent substrates, and an orientation control film 5 serving also as a protective film is applied and oriented thereon. A liquid crystal composition is sandwiched between the two. When no electric field is applied, the rod-shaped liquid crystal molecules 6
A slight angle with respect to the longitudinal direction (FIG. 1 (c) front view),
That is, they are oriented so that 45 degrees ≦ | φ _LC | <90 degrees. In FIG. 1 and FIG. 2, the liquid crystal molecule major axis alignment (rubbing) direction 10 on the interface is indicated by an arrow. The liquid crystal molecule alignment direction on the upper and lower interfaces is preferably parallel, that is, φ _LC1.
= And has a φ _LC2 (= φ _LC). The dielectric anisotropy of the liquid crystal composition is assumed to be positive.

【００２４】ここで、画素電極４と共通電極１のそれぞ
れに異なる電位を与えそれらの間に電位差を与えて液晶
組成物層に電界９を印加すると、液晶組成物が持つ誘電
異方性と電界との相互作用により図１（ｂ)，(ｄ）に示
したように液晶分子が反応して電界方向にその向きを変
える。この時液晶組成物層の屈折率異方性と偏光板との
相互作用により明るさが変わる。本発明の主要な構成の
第１は電気光学特性の最適化であり、第２は駆動条件の
最適化である。以下それぞれについてその作用について
説明する。Here, when a different potential is applied to each of the pixel electrode 4 and the common electrode 1 and a potential difference is applied between them to apply an electric field 9 to the liquid crystal composition layer, the dielectric anisotropy of the liquid crystal composition and the electric field 1 (b) and 1 (d), the liquid crystal molecules react to change the direction of the electric field. At this time, the brightness changes due to the interaction between the refractive index anisotropy of the liquid crystal composition layer and the polarizing plate. The first of the main configurations of the present invention is optimization of electro-optical characteristics, and the second is optimization of driving conditions. The operation of each will be described below.

【００２５】（１）電気光学特性の最適化（第１の構
成） はじめに、上述のような液晶分子の配向方向を変化させ
て、それにあわせて明るさを変化させる作用について説
明する。一般に一軸性複屈折性媒体を直交配置した２枚
の偏光板の間に挿入した時の光透過率Ｔ／Ｔ_o は次式で
表される。ここで、χ_eff は液晶組成物層の実効的な光
軸方向（実効的な分子長軸方向と偏光透過軸とのなす
角）、ｄ_eff は複屈折性を有する実効的な液晶組成物層
の厚み、Δｎは屈折率異方性、λは光の波長を表す。こ
こで、液晶組成物層の光軸方向を実効的な値とした目的
は、実際のセル内では界面上では液晶分子が固定されて
おり、電界印加時にはセル内で全ての液晶分子が互いに
平行かつ一様に配向しているのではなく、特に界面近傍
では大きな変形が起こっていることを鑑み、それらの平
均値として一様状態を想定した時の見かけの値で取り扱
うことにある。(1) Optimization of Electro-Optical Characteristics (First Configuration) First, the operation of changing the alignment direction of the liquid crystal molecules as described above and changing the brightness in accordance with the change will be described. General light transmission T / T _o when inserted between two polarizing plates were orthogonally arranged uniaxial birefringent medium is expressed by the following equation. Here, χ _eff is the effective optical axis direction of the liquid crystal composition layer (the angle between the effective molecular major axis direction and the polarization transmission axis), and d _eff is the effective birefringent liquid crystal composition layer. Represents the refractive index anisotropy, and λ represents the wavelength of light. Here, the purpose of setting the optical axis direction of the liquid crystal composition layer as an effective value is that liquid crystal molecules are fixed on the interface in the actual cell, and all liquid crystal molecules are parallel to each other in the cell when an electric field is applied. In addition, in consideration of the fact that the orientation is not uniform and large deformation occurs particularly in the vicinity of the interface, the average value thereof is treated as an apparent value when a uniform state is assumed.

【００２６】 Ｔ／Ｔ_o＝sin²（２χ_eff）・sin²（πｄ_eff・Δｎ／λ） …（１） 明るさを変化させる際の挙動としては、低電圧Ｖ_OFF 印
加時に暗、高電圧Ｖ_ON印加時に明状態となるノーマリク
ローズ特性と、明暗がその逆になるノーマリオープン特
性の２種類がある。本発明の第１の構成はＶ_LCを増大さ
せるに従い明るさが減少し最小値をとるように偏光板等
を設定することにある。従って、ノーマリクローズ特性
を得るには偏光板８の偏光透過軸１１と電界方向９との
なす角φ_P をラビング方向１０と電界方向９とのなす角
φ_LCより若干（２度以上３０度以下、望ましくは３度以
上１０度以下）小さな角度に配置すれば良い。こうする
ことで、あるバイアス電圧（後述するＶ_OFF ）を印加し
た状態で、（１）式におけるχ_effが０となり明るさに
対応する光透過率Ｔ／Ｔ_oも０となる。一方それより高
い電界（後述するＶ_ON）を印加する時にはその強度に応
じてχ_eff の値が増大し、４５度の時に最大になる。一
方、ノーマリオープン特性を得るには偏光板８の偏光透
過軸１１と電界方向９とのなす角φ_P をラビング方向１
０と電界方向９とのなす角φ_LCより大幅に(４５度以上)
小さな角度に配置すれば良い。いずれの特性に対して
も、無彩色でかつ透過率を最大とするには実効的なｄ
_eff・Δｎを２分の１波長である０.２８μｍ とすれば
良い（ここで光の波長は０.５５５μｍと想定した）。
現実には裕度があるために、０.２１から０.３６μｍの
間に入っていれば良いが、特に誘電率異方性が正でラビ
ング角度｜φ_LC｜を１０度以下と小さくする時にはやや
高めの０.２７から０.３３μｍの間の値に設定すると良
い。T / T _o = sin ² (2χ _eff ) · sin ² (πd _eff · Δn / λ) (1) When changing the brightness, the dark and the high voltage are applied when the low voltage V _{OFF is} applied. There are two types of normally closed characteristics, in which a bright state occurs when V _{ON is} applied, and normally open characteristics, in which the brightness is reversed. A first configuration of the present invention is to set a polarizing plate or the like such that the brightness decreases as the _VLC increases and takes a minimum value. Therefore, in order to obtain normally closed characteristics, the angle φ _P between the polarization transmission axis 11 of the polarizing plate 8 and the electric field direction 9 is slightly larger than the angle φ _LC between the rubbing direction 10 and the electric field direction 9 (2 degrees or more and 30 degrees). (Hereinafter, preferably 3 degrees or more and 10 degrees or less)). By so doing, while applying a certain bias voltage (V _OFF to be described later), a light transmission T / T _o be 0 corresponding to the chi _eff becomes zero brightness in (1). On the other hand, when a higher electric field (V _ON described later) is applied, the value of χ _eff increases in accordance with the intensity, and reaches a maximum at 45 degrees. On the other hand, in order to obtain normally open characteristics, the angle φ _P between the polarization transmission axis 11 of the polarizing plate 8 and the electric field direction 9 is set to the rubbing direction 1.
Significantly larger than angle φ _LC between 0 and electric field direction 9 (45 degrees or more)
It may be arranged at a small angle. For any characteristic, effective d is achromatic to maximize transmittance.
_eff · Δn may be set to 0.28 μm, which is a half wavelength (here, the wavelength of light is assumed to be 0.555 μm).
Actually, there is a margin, so it is sufficient if the rubbing angle | φ _LC | is as small as 10 degrees or less, especially when the dielectric anisotropy is positive and the rubbing angle | φ _LC | It is preferable to set a slightly higher value between 0.27 and 0.33 μm.

【００２７】図４にこの本発明の主要な第１の構成であ
る明るさの印加電圧依存性の曲線の一例を示す。画素電
極４と共通電極１の間に印加される電圧Ｖ_LCをほぼゼロ
から、徐々に増大させるに従い明るさが一旦減少し最小
値をとった後に再び増大し、やがて印加電圧がほぼゼロ
の時の明るさよりも高い値を取る。ここではこのように
高電圧側で明状態が表示される特性をノーマリクローズ
特性と呼ぶ。一方、図５には高電圧側で暗状態となるノ
ーマリオープン特性の一例を示す。なお、ここではいず
れの場合も複屈折モードを採用し、液晶組成物層を挟持
している２枚の偏光板の偏光透過軸はほぼ直交させた
が、上述のようなある一定幅の電圧範囲で明暗２状態が
表示できる特性を実現する手段であればこれに限らな
い。なお、本発明ではいずれの特性に対しても明るさが
ほぼ最小値となる電圧をＶ_OFF と定義し、より明るい状
態を得る電圧をＶ_ONと定義する（図４，図５）。FIG. 4 shows an example of a curve of the applied voltage dependence of the brightness, which is the main first configuration of the present invention. When the voltage _VLC applied between the pixel electrode 4 and the common electrode 1 is gradually increased from almost zero, the brightness temporarily decreases, takes a minimum value, then increases again, and finally when the applied voltage is almost zero. Take a value higher than the brightness. Here, such a characteristic that a bright state is displayed on the high voltage side is called a normally closed characteristic. On the other hand, FIG. 5 shows an example of a normally open characteristic in which a dark state occurs on the high voltage side. Here, in each case, the birefringence mode was adopted, and the polarization transmission axes of the two polarizing plates sandwiching the liquid crystal composition layer were substantially perpendicular to each other. However, the present invention is not limited to this as long as it is a means for realizing a characteristic capable of displaying two states of light and dark. In the present invention, the voltage at which the brightness becomes substantially the minimum value for any characteristic is defined as V _OFF, and the voltage for obtaining a brighter state is defined as V _ON (FIGS. 4 and 5).

【００２８】（２）駆動条件の最適化（第２の構成） 次に、上記の主要な第１の構成と主要な第２の構成であ
る以下の駆動方法とを組み合わせることで駆動ＩＣの電
圧を大幅に引き下げることが可能となる作用について説
明する。図１０に本発明の駆動回路システムを示す。本
発明では一般的な薄膜トランジスタ型表示装置の駆動回
路と同様に走査電極駆動回路１８と信号電極駆動回路１
９とからなるが、加えて共通電極にも電圧波形を印加す
る駆動回路２０も備える。図９にはこの回路による駆動
波形の一例を示す。図９（ａ）は走査電極駆動回路から
供給される走査波形Ｖ_G を、図９（ｂ）は信号電極駆動
回路から供給される画像情報を担った信号波形Ｖ_D をし
めす。図９（ｃ）は共通電極に供給する波形Ｖ_C を、図
９（ｄ）は画素電極であるソース電極にかかる電圧Ｖ_S
を、そして図９（ｅ）は液晶にかかる電圧Ｖ_LCを表す。
ここで、共通電極に供給する波形Ｖ_Cは信号波形Ｖ_Dと同
期をとりかつその位相を逆にして、液晶に印加される実
効電圧が、共通電極からの電圧波形の振幅Ｖ_C がゼロの
場合よりも著しく高められるようにしている。(2) Optimization of Driving Conditions (Second Configuration) Next, the voltage of the driving IC is obtained by combining the above-described main first configuration and the following main second configuration driving method. Will be described below. FIG. 10 shows a drive circuit system according to the present invention. In the present invention, the scan electrode drive circuit 18 and the signal electrode drive circuit 1 are provided in the same manner as the drive circuit of a general thin film transistor type display device.
9, and a drive circuit 20 for applying a voltage waveform also to the common electrode. FIG. 9 shows an example of a driving waveform by this circuit. 9 (a) is a scanning waveform V _G supplied from the scan electrode driving circuit, FIG. 9 (b) shows the signal waveforms V _D which played an image information supplied from the signal electrode driving circuit. FIG. 9C shows a waveform V _C supplied to the common electrode, and FIG. 9D shows a voltage V _S applied to the source electrode which is a pixel electrode.
And FIG. 9 (e) shows the voltage _VLC applied to the liquid crystal.
Here, the waveform V _C supplied to the common electrode is synchronized with the signal waveform V _D and its phase is reversed, so that the effective voltage applied to the liquid crystal is such that the amplitude V _C of the voltage waveform from the common electrode is zero. It is made to be significantly higher than the case.

【００２９】本発明では、共通電極にも電圧波形を印加
する駆動回路２０を備えているが、前述の電気光学的特
性とこの簡素な回路とを組み合わせることにより、もっ
とも数多く使用しかつ画像情報を担うために高価になる
信号電極駆動回路のコストを低減できる。全回路コスト
のかなりの部分を占める信号電極駆動回路のコスト低減
は表示装置全体のコスト低減に大きく寄与する。一般に
駆動ＩＣの製造コストは耐圧（最大出力電圧）に強く依
存し、低いほど低減しやすい。一方、共通電極駆動回路
の方は基本的には出力端子が１つあれば十分であり、ま
た画像情報を担わせる必要もなく出力電圧を多少高くし
てもさほど大きなコスト上昇には結びつかない。図９か
らも明らかなように、共通電極に信号電圧波形と逆位相
の電圧波形を印加すると液晶にかかる実効電圧Ｖ_LCが高
まる。液晶にかかる実効電圧Ｖ_LCは画素電極であるソー
ス電極にかかる電圧Ｖ_Sから共通電極からの電圧Ｖ_Cを引
いた電圧になる。また、ゲートがオフの時の画素電極
（ソース電極）にかかる電圧の振幅ΔＶ_Sは信号電極に
かかる電圧Ｖ_Dのピークツーピーク値｜Ｖ_DH−Ｖ_DL｜に
ほぼ比例する。したがって、信号電極にかかる電圧、即
ち画素電極(ソース電極)にかかる電圧波形と共通電極に
かかる電圧波形とが互いに逆位相の関係にあれば、液晶
にかかる実効電圧Ｖ_LCのピークツーピーク値はそれらの
和になり、信号電極にかかる電圧が低くとも液晶により
高い電圧がかけられる。図４からも明らかなように変化
できる電圧範囲（ダイナミックレンジとも称す）はΔＶ
_S であるため、上述の主要な第１の構成として示した偏
光板等の設定により、明るさの最小値を得る電圧Ｖ_OFF
と、十分な明るさが得られる電圧Ｖ_ONとの差のダイナミ
ックレンジに対応する電圧幅が狭められ、より信号電圧
波形の振幅が低く抑制される。In the present invention, the drive circuit 20 for applying a voltage waveform to the common electrode is also provided. By combining the above-mentioned electro-optical characteristics with this simple circuit, the most frequently used and the image information can be used. It is possible to reduce the cost of the signal electrode drive circuit which becomes expensive to carry. The reduction in the cost of the signal electrode driving circuit, which accounts for a considerable portion of the total circuit cost, greatly contributes to the reduction in the cost of the entire display device. Generally, the manufacturing cost of a drive IC strongly depends on the withstand voltage (maximum output voltage), and the lower the cost, the easier it is to reduce. On the other hand, the common electrode drive circuit basically requires only one output terminal, and it is not necessary to carry image information, and a slight increase in output voltage does not lead to a significant increase in cost. As is clear from FIG. 9, when a voltage waveform having a phase opposite to the signal voltage waveform is applied to the common electrode, the effective voltage _VLC applied to the liquid crystal increases. The effective voltage V _LC applied to the liquid crystal is a voltage obtained by subtracting the voltage V _C from the common electrode from the voltage V _S applied to the source electrode which is a pixel electrode. In addition, the amplitude ΔV _S of the voltage applied to the pixel electrode (source electrode) when the gate is off is substantially proportional to the peak-to-peak value | V _DH −V _DL | of the voltage V _D applied to the signal electrode. Therefore, if the voltage applied to the signal electrode, that is, the voltage waveform applied to the pixel electrode (source electrode) and the voltage waveform applied to the common electrode have an opposite phase relationship, the peak-to-peak value of the effective voltage _VLC applied to the liquid crystal is The sum of them is obtained, and a higher voltage is applied to the liquid crystal even if the voltage applied to the signal electrode is lower. As is clear from FIG. 4, the voltage range that can be changed (also called dynamic range) is ΔV
_Since it is _S , the voltage V _OFF at which the minimum value of brightness is obtained by setting the polarizing plate and the like shown as the main first configuration described above.
Then, the voltage width corresponding to the dynamic range of the difference from the voltage V _ON at which sufficient brightness is obtained is narrowed, and the amplitude of the signal voltage waveform is suppressed to be lower.

【００３０】なお、Ｖ_OFF とＶ_ONの差は界面上の液晶の
配向方向（ラビング方向）に強く依存し、液晶の誘電率
異方性が正の場合、角度｜φ_LC｜を９０度未満の範囲で
できるだけ大きくとることが効果的である。液晶の誘電
率異方性が負の場合は逆に角度｜φ_LC｜を０度を越える
範囲でできるだけ小さくとると良い。The difference between V _OFF and V _ON strongly depends on the orientation direction (rubbing direction) of the liquid crystal on the interface. When the dielectric anisotropy of the liquid crystal is positive, the angle | φ _LC | It is effective to take as large as possible within the range. If the dielectric anisotropy of the liquid crystal is negative, the angle | φ _LC | should be made as small as possible within a range exceeding 0 °.

【００３１】[0031]

【実施例】本発明を実施例により具体的に説明する。EXAMPLES The present invention will be specifically described with reference to examples.

【００３２】〔実施例１〕基板としては厚みが１.１mm
で表面を研磨した透明なガラス基板を２枚用いる。これ
らの基板のうち一方の基板の上に薄膜トランジスタを形
成し、更にその上の最表面に絶縁膜兼用の配向膜を形成
した。本実施例では配向膜としてポリイミドを採用し、
その上を液晶を配向させるためのラビング処理をした。
他方の基板上にもポリイミドを塗布し同様のラビング処
理をした。上下界面上のラビング方向は互いにほぼ平行
で、かつ印加電界方向とのなす角度を８８度（φ_LC1＝
φ_LC2＝８８°）とした。これらの基板間に誘電率異方
性Δεが正でその値が４.５ であり、屈折率異方性Δｎ
が０.０７２(５８９ｎｍ，２０℃）のネマチック液晶組
成物を挟んだ。ギャップｄは球形のポリマビーズを基板
間に分散して挾持し、液晶封入状態で３.９μｍとし
た。よってΔｎ・ｄは０.２８１μｍである。２枚の偏
光板〔日東電工社製Ｇ１２２０ＤＵ〕でパネルを挾み、
一方の偏光板の偏光透過軸をラビング方向より若干小さ
な角度、即ちφ_P1＝８０°（即ち、｜φ_LC1−φ_P1｜＝
８°）に設定し、他方をそれに直交、即ちφ_P2＝−１２
°とした。これにより、本発明の第１の主要構成である
画素に印加される電圧Ｖ_LCをゼロから徐々に増大させる
にしたがい明るさが減少し最小値をとる特性（図４）を
得た。本実施例では低電圧(Ｖ_OFF）で暗状態、高電圧
（Ｖ_ON）で明状態をとるノーマリクローズ特性を採用し
た。Ｖ_OFFは６.９Ｖ、Ｖ_ONは９.１Ｖである。Example 1 The thickness of the substrate was 1.1 mm.
Use two transparent glass substrates whose surfaces have been polished. A thin film transistor was formed on one of these substrates, and an alignment film also serving as an insulating film was formed on the uppermost surface thereof. In this embodiment, polyimide is adopted as the alignment film,
A rubbing treatment for aligning the liquid crystal was performed thereon.
The other substrate was also coated with polyimide and subjected to the same rubbing treatment. The rubbing directions on the upper and lower interfaces are substantially parallel to each other, and the angle between the rubbing directions and the direction of the applied electric field is 88 degrees (φ _LC1 =
φ _LC2 = 88 °). The dielectric anisotropy Δε is positive and 4.5 between these substrates, and the refractive index anisotropy Δn is
Of a nematic liquid crystal composition of 0.072 (589 nm, 20 ° C.). The gap d was 3.9 μm in a state in which liquid crystal was sealed while spherical polymer beads were dispersed and sandwiched between substrates. Therefore, Δn · d is 0.281 μm. The panel is sandwiched between two polarizing plates (G1220DU manufactured by Nitto Denko Corporation)
The polarization transmission axis of one of the polarizing plates is slightly smaller than the rubbing direction, that is, φ _P1 = 80 ° (that is, | φ _LC1 −φ _P1 | =
8 °) and the other is orthogonal to it, ie φ _P2 = -12.
°. As a result, a characteristic (FIG. 4) in which the brightness decreases and takes the minimum value as the voltage _VLC applied to the pixel, which is the first main configuration of the present invention, gradually increases from zero is obtained. In the present embodiment, a normally-closed characteristic is employed in which a dark state occurs at a low voltage (V _OFF ) and a bright state occurs at a high voltage (V _ON ). V _OFF is 6.9V and V _ON is 9.1V.

【００３３】薄膜トランジスタ及び各種電極の構造を図
３に示す。図３（ａ）は基板面に垂直な方向から見た正
面図、図３（ｂ)，(ｃ）は側断面図を表す。薄膜トラン
ジスタ素子１４は画素電極（ソース電極）４，信号電極
（ドレイン電極）３，走査電極（ゲート電極）１２、及
びアモルファスシリコン１３から構成される。共通電極
１と走査電極１２、及び信号電極３と画素電極４とはそ
れぞれ同一の金属層をパターン化して構成した。容量素
子１６は、２本の共通電極１の間を結合する領域（図３
において点線で示した）において画素電極４と共通電極
１で絶縁保護膜２を挟む構造として形成した。画素電極
は正面図（図３（ａ））において、２本の共通電極１の
間に配置されている。画素ピッチは横方向（すなわち信
号配線電極間）は６９μｍ、縦方向（すなわち走査配線
電極間）は２０７μｍである。電極幅は、複数画素間に
またがる配線電極である走査電極，信号電極，共通電極
配線部（走査配線電極に平行（図３で横方向）に延びた
部分）を広めにし、線欠陥を回避した。幅はそれぞれ１
０μｍである。一方、開口率向上のために１画素単位で
独立に形成した画素電極、及び共通電極の信号配線電極
の長手方向に伸びた部分の幅は若干狭くし、それぞれ５
μｍ，８μｍとした。これらの電極の幅を狭くしたこと
で異物等の混入により断線する可能性が高まるが、この
場合１画素の部分的欠落ですみ線欠陥には至らない。加
えて、更にできるだけ高い開口率を実現するために絶縁
膜を介して共通電極と信号電極を若干（１μｍ）重ね
た。これにより、信号配線に平行な方向のブラックマト
リクスは不要になる。そこで図３（ｃ）に示されている
ように、走査配線電極方向のみ遮光するブラックマトリ
クス構造とした。このようにして、共通電極と画素電極
とのギャップが２０μｍ、開口部の長手方向の長さ１５
７μｍとなり、４４.０％ の高開口率が得られた。画素
数は３２０本の信号配線電極と１６０本の配線電極とに
より３２０×１６０個とした。複数画素から構成される
パネルの部分を図１３，図１４に示す。図１３ではブラ
ックマトリクスを省略し、図１４ではブラックマトリク
スで遮光した状態を示した。FIG. 3 shows the structure of the thin film transistor and various electrodes. FIG. 3A is a front view seen from a direction perpendicular to the substrate surface, and FIGS. 3B and 3C are side sectional views. The thin film transistor element 14 includes a pixel electrode (source electrode) 4, a signal electrode (drain electrode) 3, a scanning electrode (gate electrode) 12, and amorphous silicon 13. The common electrode 1 and the scanning electrode 12, and the signal electrode 3 and the pixel electrode 4 were each formed by patterning the same metal layer. The capacitive element 16 is a region that couples between the two common electrodes 1 (FIG. 3).
(Indicated by a dotted line in FIG. 3)), the pixel electrode 4 and the common electrode 1 sandwich the insulating protective film 2. The pixel electrode is disposed between two common electrodes 1 in a front view (FIG. 3A). The pixel pitch is 69 μm in the horizontal direction (ie, between signal wiring electrodes), and 207 μm in the vertical direction (ie, between scanning wiring electrodes). As for the electrode width, a scanning electrode, a signal electrode, and a common electrode wiring portion (a portion extending in a direction parallel to the scanning wiring electrode (in the horizontal direction in FIG. 3)), which are wiring electrodes extending over a plurality of pixels, are widened to avoid line defects. . The width is 1 each
0 μm. On the other hand, the width of the pixel electrode independently formed in one pixel unit for improving the aperture ratio and the width of the portion of the signal wiring electrode of the common electrode extending in the longitudinal direction are slightly reduced to 5
μm and 8 μm. By reducing the width of these electrodes, the possibility of disconnection due to the incorporation of foreign matter or the like increases, but in this case, a partial defect of one pixel does not result in a line defect. In addition, the common electrode and the signal electrode were slightly overlapped (1 μm) via an insulating film in order to achieve an aperture ratio as high as possible. This eliminates the need for a black matrix in the direction parallel to the signal wiring. Therefore, as shown in FIG. 3C, a black matrix structure that shields light only in the direction of the scanning wiring electrode is adopted. Thus, the gap between the common electrode and the pixel electrode is 20 μm, and the length of the opening in the longitudinal direction is 15 μm.
7 μm, and a high aperture ratio of 44.0% was obtained. The number of pixels was 320 × 160 with 320 signal wiring electrodes and 160 wiring electrodes. FIGS. 13 and 14 show a part of a panel including a plurality of pixels. 13 omits the black matrix, and FIG. 14 shows a state where light is shielded by the black matrix.

【００３４】次に、回路構成及び駆動波形について説明
する。各走査配線１２および各信号配線３にはそれぞれ
走査電極駆動用回路１８および信号電極駆動用回路１９
を接続した。また、共通電極１にも共通電極駆動用回路
２０を接続した(図１０)。信号電極３には情報を有する
信号波形が印加され、走査電極１２には走査波形が信号
波形と同期をとって印加される。信号電極３から薄膜ト
ランジスタ１４を介して画素電極４に情報信号が伝達さ
れ、共通電極１との間で液晶部分に電圧が印加される。
本発明では共通電極にも電圧波形を印加しており、その
分より高い電圧が液晶層にかかる。各配線電極への印加
電圧波形を図９に示す。なお、図９の電圧波形の振幅
は、 Ｖ_D-CENTER＝１４.０，Ｖ_GH＝２８.０，Ｖ_GL＝０，Ｖ_DH
＝１５.１， Ｖ_DL＝１２.９，Ｖ_CH＝２０.４，Ｖ_CL＝４.３９ に設定し、その結果、ゲート電極とソース電極の間の寄
生容量による飛込み電圧ΔＶ_GS(+)，ΔＶ_GS(-)，画素電
極にかかる電圧Ｖ_S ，液晶にかかる電圧Ｖ_LCは下表のよ
うになった。なお、電圧の単位は以後すべてボルトとす
る。Next, the circuit configuration and drive waveforms will be described. Each of the scanning wirings 12 and each of the signal wirings 3 have a scanning electrode driving circuit 18 and a signal electrode driving circuit 19, respectively.
Connected. The common electrode driving circuit 20 was also connected to the common electrode 1 (FIG. 10). A signal waveform having information is applied to the signal electrode 3, and a scanning waveform is applied to the scanning electrode 12 in synchronization with the signal waveform. An information signal is transmitted from the signal electrode 3 to the pixel electrode 4 via the thin film transistor 14, and a voltage is applied between the common electrode 1 and the liquid crystal portion.
In the present invention, a voltage waveform is also applied to the common electrode, and a higher voltage is applied to the liquid crystal layer. FIG. 9 shows the waveform of the voltage applied to each wiring electrode. Note that the amplitude of the voltage waveform in FIG. 9 is V _D-CENTER = 14.0, V _GH = 28.0, V _GL = 0, V _DH
= 15.1, V _DL = 12.9, V _CH = 20.4, V _CL = 4.39, and as a result, the jump voltage ΔV _GS (+) due to the parasitic capacitance between the gate electrode and the source electrode. , ΔV _GS (−), voltage V _S applied to the pixel electrode, and voltage V _LC applied to the liquid crystal are as shown in the table below. The unit of the voltage is hereinafter all volts.

【００３５】[0035]

【表１】 [Table 1]

【００３６】図４に示すＶ_ON，Ｖ_OFF はそれぞれ９.１
６ボルト，６.８５ボルトとなり、十分に高いコントラ
スト比８０が得られた。V _ON and V _OFF shown in FIG.
6 volts and 6.85 volts, and a sufficiently high contrast ratio 80 was obtained.

【００３７】なお、本実施例では信号配線電極に供給す
る駆動電圧波形の振幅Ｖ_DP-P(≡V_DH−Ｖ_DL）は僅かに
２.２ ボルトという大変に低い値で駆動できた。In the present embodiment, the drive voltage waveform supplied to the signal wiring electrode could be driven at a very low amplitude V _DP-P (≡V _DH −V _DL ) of only 2.2 volts.

【００３８】〔比較例１〕実施例１のφ_P1およびφ_P2を
それぞれ８８°，−２°に設定し、電圧がゼロの時に最
も暗くなる特性を得た（図４）。駆動電圧波形等他の構
成は実施例１と同一とした。Ｖ_OFF における明るさが１
２％もあり僅かに８という低いコントラスト比しか得ら
れなかった。Comparative Example 1 φ _P1 and φ _P2 of Example 1 were set to 88 ° and −2 °, respectively, to obtain the characteristic of becoming darkest when the voltage was zero (FIG. 4). Other configurations such as the driving voltage waveform were the same as those in the first embodiment. Brightness at V _OFF is 1
There was as much as 2%, and a contrast ratio as low as 8 was obtained.

【００３９】〔比較例２〕実施例１のφ_P1およびφ_P2を
それぞれ８８°，−２°に設定し、電圧がゼロの時に最
も暗くなる特性を得た（図４）。このような特性の変化
に合わせて駆動電圧波形も変えた。即ち、図９のＶ_Cを
１２.４ボルトの一定レベルとし、Ｖ_DHを１８.５ボルト
とし、Ｖ_DLを９.５ボルトとし、９.０ボルトのＶ_DP-P
を得た。従って、Ｖ_DP-Pは実施例１の２.２ボルト比べ
て非常に高くなった。Comparative Example 2 φ _P1 and φ _P2 of Example 1 were set to 88 ° and −2 °, respectively, to obtain the characteristic of becoming darkest when the voltage was zero (FIG. 4). The drive voltage waveform was also changed in accordance with such a change in the characteristics. That is, V _C in FIG. 9 is a constant level of 12.4 volts, V _DH is 18.5 volts, V _DL is 9.5 volts, and 9.0 volts V _DP-P
I got Therefore, V _DP-P was much higher than 2.2 volts of Example 1.

【００４０】〔実施例２〕本実施例では実施例１のφ
_LC1を８８.５°、φ_P1およびφ_P2をそれぞれ88.5°，−
１.５°に設定し、液晶のギャップを４.３μｍと若干高
めた。Δｎ・ｄは０.３１０μｍ となった。発明者らの
実験によると、Δｎ・ｄを２分の１波長である０.２８
μｍ程度に固定したままφ_LC1を９０°に近づけてゆく
と、φ_LC1 が約７５°の時に透過率が最大になり再び減
少する。これは電圧印加時の液晶配向状態が単純な一軸
配向状態ではなく、３次元的に分布しているためであ
る。そこで、発明者らが鋭意検討した結果、特に９０°
に近い場合（８５°以上）は見かけのΔｎ・ｄが若干減
少するため、それを補償するように少し高めの値（0.31
±０.０５μｍ)に設定すれば良いことが分かった。本実
施例ではこの点を考慮して、液晶のギャップを設定し
た。その結果、図８に示す特性を得た。[Embodiment 2] In this embodiment, φ of Embodiment 1
_LC1 at 88.5 °, φ _P1 and φ _P2 at 88.5 °,-
The angle was set to 1.5 °, and the gap of the liquid crystal was slightly increased to 4.3 μm. Δn · d was 0.310 μm. According to experiments by the inventors, Δn · d is 0.28 which is a half wavelength.
When φ _LC1 is approached to 90 ° while being fixed at about μm, the transmittance becomes maximum when φ _LC1 is about 75 ° and decreases again. This is because the liquid crystal alignment state when voltage is applied is not a simple uniaxial alignment state, but is distributed three-dimensionally. Then, as a result of the inventor's intensive study, especially 90 °
When the value is close to (85 ° or more), the apparent Δn · d is slightly reduced, and a slightly higher value (0.31
(± 0.05 μm). In this embodiment, the gap of the liquid crystal is set in consideration of this point. As a result, the characteristics shown in FIG. 8 were obtained.

【００４１】ラビング方向と一方の偏光板偏光透過軸方
向を平行（即ち、φ_LC1＝φ_P1)とした結果、電圧ゼロで
の明るさが非常に低くなった。Ｖ_OFFの最大値、および
Ｖ_ONはそれぞれ５.０ボルト、８.８ボルトとなった。こ
の特性に合わせて、共通電極に印加する電圧Ｖ_CP-P／２
も６.９ ボルトに設定した。他の構成は実施例１と同一
である。その結果、信号配線電極に供給する駆動電圧波
形の振幅Ｖ_DP-Pは3.8ボルトという低い値にでき、コン
トラスト比も２５０という非常に高い値を得た。When the rubbing direction was parallel to the polarization transmission axis direction of one of the polarizing plates (that is, φ _LC1 = φ _P1 ), the brightness at zero voltage was very low. The maximum value of V _OFF and V _ON were 5.0 volts and 8.8 volts, respectively. According to this characteristic, the voltage V _CP-P / 2 applied to the common electrode
Was also set to 6.9 volts. Other configurations are the same as those of the first embodiment. As a result, the amplitude V _DP-P of the drive voltage waveform supplied to the signal wiring electrode could be set to a low value of 3.8 volts, and the contrast ratio obtained a very high value of 250.

【００４２】〔実施例３〕本実施例では実施例１のφ_P1
およびφ_P2をそれぞれ３８°，−５２°に設定し、図５
に示すノーマリオープン特性を得た。他の構成は実施例
１と同一である。Ｖ_ON，Ｖ_OFF 共に実施例１とほぼ等し
くなった。６０というコントラスト比を得た。[Embodiment 3] In this embodiment, φ _{P1 of} Embodiment 1 is used.
And φ _P2 were set to 38 ° and −52 °, respectively, and FIG.
The normally open characteristics shown in the following were obtained. Other configurations are the same as those of the first embodiment. Both V _ON and V _OFF were almost equal to those in the first embodiment. A contrast ratio of 60 was obtained.

【００４３】実施例１と同様に信号配線電極に供給する
駆動電圧波形の振幅Ｖ_DP-Pは僅かに２.２ ボルトという
大変に低い値で駆動できた。As in the first embodiment, the amplitude V _DP-P of the drive voltage waveform supplied to the signal wiring electrodes could be driven at a very low value of only 2.2 volts.

【００４４】〔実施例４〜６〕本実施例では実施例１の
φ_LCを７５度，８８度，８９.５ 度とした。また、｜φ
_LC−φ_P1｜は５度とした。他の構成は実施例１と同一で
ある。その結果、図６に示すような特性が得られ、
Ｖ_ON，Ｖ_OFF はそれぞれ以下の表のようになった。[Embodiments 4 to 6] In this embodiment, φ _{LC of} Embodiment 1 was set to 75 °, 88 °, and 89.5 °. Also, | φ
_{LC -φ P1} | was 5 degrees. Other configurations are the same as those of the first embodiment. As a result, characteristics as shown in FIG. 6 are obtained,
V _ON and V _OFF were as shown in the following table, respectively.

【００４５】[0045]

【表２】 [Table 2]

【００４６】いずれの実施例においても、５.０ ボルト
以下という低いＶ_DP-P（信号配線電極に供給する駆動電
圧波形の振幅）で駆動でき、コントラスト比も十分に高
い値を得た。In any of the examples, the driving was possible at a low V _DP-P (amplitude of the driving voltage waveform supplied to the signal wiring electrode) of 5.0 volts or less, and a sufficiently high contrast ratio was obtained.

【００４７】〔実施例７〕液晶材料をメルク社製ＺＬＩ
−２８０６に換えた。誘電率異方性Δεは負でその値は
−４.８であり、屈折率異方性Δｎは０.０４３７であ
る。Δｎ・ｄを望ましい範囲にとするためにギャップｄ
を６.３μｍ とした。よって、Δｎ・ｄは０.２７５で
ある。ラビング方向と印加電界方向とのなす角度を１５
度（φ_LC1＝φ_LC2＝１５°)とした。２枚の偏光板〔日
東電工社製Ｇ１２２０ＤＵ〕でパネルを挾み、一方の偏
光板の偏光透過軸をラビング方向より若干大きな角度、
即ちφ_P1＝２０°に設定し、他方をそれに直交、即ちφ
_P2＝−７０°とした。これにより、本発明の第１の主要
構成である画素に印加される電圧Ｖ_LCをゼロから徐々に
増大させるにしたがい明るさが減少し最小値をとる特性
（図７）を得た。本実施例では低電圧(Ｖ_OFF）で暗状
態、高電圧（Ｖ_ON）で明状態をとるノーマリクローズ特
性を採用した。Ｖ_OFFは２.９Ｖ、Ｖ_ONは９.４Ｖ であ
る。以上の点を除けば他は実施例１と同じである。Example 7 The liquid crystal material was ZLI manufactured by Merck.
-2806. The dielectric anisotropy Δε is negative and its value is −4.8, and the refractive index anisotropy Δn is 0.0437. In order to set Δn · d in a desired range, the gap d
Was set to 6.3 μm. Therefore, Δn · d is 0.275. The angle between the rubbing direction and the applied electric field direction is 15
(Φ _LC1 = φ _LC2 = 15 °). The panel is sandwiched between two polarizing plates (G1220DU manufactured by Nitto Denko Corporation), and the polarization transmission axis of one of the polarizing plates has an angle slightly larger than the rubbing direction.
That is, φ _P1 = 20 ° is set, and the other is perpendicular to it, ie, φ
_{P2 was set to} -70 °. Thus, a characteristic (FIG. 7) in which the brightness decreases and takes the minimum value as the voltage _VLC applied to the pixel, which is the first main configuration of the present invention, gradually increases from zero is obtained. In the present embodiment, a normally-closed characteristic is employed in which a dark state occurs at a low voltage (V _OFF ) and a bright state occurs at a high voltage (V _ON ). V _OFF is 2.9V and V _ON is 9.4V. Except for the above points, the other points are the same as those of the first embodiment.

【００４８】６.５ボルトという低いＶ_DP-P（信号配線
電極に供給する駆動電圧波形の振幅)で駆動でき、コン
トラスト比も１８０という十分に高い値を得た。Driving was possible at a low V _DP-P (amplitude of the driving voltage waveform supplied to the signal wiring electrode) of 6.5 volts, and a sufficiently high contrast ratio of 180 was obtained.

【００４９】〔比較例３〕実施例７のφ_P1およびφ_P2を
ラビング方向と同一にし、それぞれ１５°，−７５°に
設定し、電圧がゼロの時に最も暗くなる特性を得た（図
７）。駆動電圧波形等他の構成は実施例７と同一とし
た。Ｖ_OFF における明るさが７％もあり僅かに１１とい
う低いコントラスト比しか得られなかった。Comparative Example 3 φ _P1 and φ _P2 in Example 7 were set to be the same as the rubbing direction, and were set to 15 ° and −75 °, respectively, to obtain the characteristic of darkening when the voltage was zero (FIG. 7). ). Other configurations such as the drive voltage waveform were the same as those of the seventh embodiment. The brightness at V _OFF was as high as 7%, and only a low contrast ratio of 11 was obtained.

【００５０】〔実施例８〕φ_LC1，φ_LC2をそれぞれ１.
５°、ギャップｄを７.２μｍ、Δｎ・ｄを0.315μｍと
した。一方の偏光板の偏光透過軸をラビング方向にほぼ
平行、即ちφ_P1＝２.５°に設定し、他方をそれに直
交、即ちφ_P2＝−８７.５°とした。他の条件は、実施
例７と同一である。その結果、暗状態を得る電圧Ｖ_OFF
が５.２ボルト、明状態を得る電圧Ｖ_ONが７.８ ボルト
となった。この特性に合わせて、共通電極に印加する電
圧Ｖ_CP-P／２も６.５ ボルトに設定した。他の構成は実
施例１と同一である。その結果、信号配線電極に供給す
る駆動電圧波形の振幅Ｖ_DP-Pは2.6ボルトという低い値
にでき、コントラスト比も１６０という高い値を得た。Embodiment 8 Each of φ _LC1 and φ _LC2 was 1.
5 °, the gap d was 7.2 μm, and Δn · d was 0.315 μm. The polarization transmission axis of one of the polarizing plates was set substantially parallel to the rubbing direction, ie, φ _P1 = 2.5 °, and the other was perpendicular to it, ie, φ _P2 = -87.5 °. Other conditions are the same as in the seventh embodiment. As a result, the voltage V _OFF for obtaining a dark state
Was 5.2 volts, and the voltage V _ON for obtaining a bright state was 7.8 volts. In accordance with this characteristic, the voltage V _CP-P / 2 applied to the common electrode was also set at 6.5 volts. Other configurations are the same as those of the first embodiment. As a result, the amplitude V _DP-P of the drive voltage waveform supplied to the signal wiring electrode could be as low as 2.6 volts, and the contrast ratio was as high as 160.

【００５１】〔実施例９〕本実施例は駆動方式が異なる
点を除けば実施例１と同一である。本実施例の駆動波形
を図１２に示す。実施例１と異なる点は、走査配線電極
に供給する電圧波形Ｖ_GのレベルがＶ_GHとＶ_GLの２値だ
ったものが、Ｖ_GLが更にＶ_GLHとＶ_GLL に分かれ合計３
値になった点にある。Ｖ_GLHとＶ_GLLはそれぞれＶ_CHとＶ
_CLと同一に設定した。[Embodiment 9] This embodiment is the same as Embodiment 1 except that the driving method is different. FIG. 12 shows the driving waveform of the present embodiment. Example 1 differs from those levels of the voltage waveform V _G supplied to the scanning wiring electrode was 2 value of V _GH and V _GL is, V _GL total divided into more V _GLH and V _GLL 3
At the point where the value is reached. V _GLH and V _GLL are V _CH and V, respectively.
Set the same as _CL .

【００５２】本発明では主として基板面に平行な電界を
印加することで明るさを変化させているが、この場合液
晶部分を電気回路として見ると基板面に垂直な電界を印
加する現行方式と比較して容量成分が著しく低い。これ
は、電極が面状であったものが線状になったこと、およ
び電極間ギャップが広がったことによる。図１１に１画
素の透過回路を示す。液晶の容量Ｃ_LCが上述のように小
さくなったため、走査配線電極と信号配線電極との間に
止むなく形成されてしまう寄生容量Ｃ_GSが相対的に増大
してしまう。本実施例の場合Ｃ_LCが３０ｆＦ程度である
のに対し、Ｃ_GSは２０〜５０ｆＦとなる。この寄生容量
は、図９に示す飛込み電圧ΔＶ_GSの大きさを支配し、画
素に印加する実効電圧の変動要因になる。本実施例で
は、この現象を抑制するために、極力走査配線電極と共
通電極の間の電位差を抑制するように、選択期間以外に
はゲート電極の電位と共通電極の電位とがほぼ同一とな
るように走査配線電極に供給する駆動波形を設計した。
各種電位は、走査配線電極への供給電位のレベル３値と
したこと以外は実施例１と基本的には同様である。In the present invention, the brightness is changed mainly by applying an electric field parallel to the substrate surface. In this case, when the liquid crystal portion is viewed as an electric circuit, it is compared with the current system in which an electric field perpendicular to the substrate surface is applied. And the capacity component is remarkably low. This is because the electrodes were planar instead of planar, and the interelectrode gap was widened. FIG. 11 shows a transmission circuit of one pixel. Since the capacitance C _{LC of the} liquid crystal is reduced as described above, the parasitic capacitance C _{GS that} is continuously formed between the scanning wiring electrode and the signal wiring electrode relatively increases. While in the present embodiment C _LC is approximately 30 fF, C _GS is the 20～50FF. This parasitic capacitance governs the magnitude of the jump voltage ΔV _GS shown in FIG. 9 and is a factor in the variation of the effective voltage applied to the pixel. In the present embodiment, in order to suppress this phenomenon, the potential of the gate electrode and the potential of the common electrode become almost the same except during the selection period so that the potential difference between the scanning wiring electrode and the common electrode is suppressed as much as possible. The drive waveform supplied to the scanning wiring electrode was designed as described above.
The various potentials are basically the same as those of the first embodiment except that the level of the supply potential to the scanning wiring electrode is set to three levels.

【００５３】本実施例では共通電極に印加する電圧波形
としてフレームごとにレベルを変えるフレーム反転方式
を採用したが、共通電極に印加する電圧波形を線順次で
ラインごとにレベルを変えるライン反転方式を採用して
も良い。いずれの場合も、寄生容量の影響が抑制でき、
負荷容量Ｃ_S も小さく（除去も可能）できる。負荷容量
の低減は更に駆動ＩＣの負荷を引き下げるのに有効であ
り、より安価なＩＣの適用が可能となる。In the present embodiment, the frame inversion method of changing the level for each frame as the voltage waveform applied to the common electrode is adopted. However, the line inversion method of changing the level of the voltage waveform applied to the common electrode line by line in line order is adopted. You may adopt it. In either case, the effect of parasitic capacitance can be suppressed,
The load capacity C _S can also be reduced (can be removed). The reduction of the load capacity is effective for further reducing the load of the driving IC, so that a cheaper IC can be applied.

【００５４】[0054]

【発明の効果】本発明によれば、界面方向の電界により
液晶をスイッチングする方式の難点であった低駆動電圧
化，高画素開口率化を実現し、低消費電力のＩＣで構成
され明るくかつ視角特性が良好で低コストの薄膜トラン
ジスタ型液晶表示装置を提供することができる。According to the present invention, a low driving voltage and a high pixel aperture ratio, which are the drawbacks of the method of switching the liquid crystal by the electric field in the interface direction, are realized. A low-cost thin film transistor liquid crystal display device having good viewing angle characteristics can be provided.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の液晶表示装置における液晶の動作を示
す図。FIG. 1 is a diagram showing an operation of a liquid crystal in a liquid crystal display device of the present invention.

【図２】電界方向に対する、界面上の分子長軸配向方向
（ラビング方向）φ_LC，偏光板偏光軸方向φ_Pのなす角
を示す図。FIG. 2 is a diagram showing an angle formed by a molecular long axis alignment direction (rubbing direction) φ _LC and a polarizing plate polarization axis direction φ _P on an interface with respect to an electric field direction.

【図３】本発明の薄膜トランジスタ，電極，配線の構造
を示す図。（ａ）正面図、(ｂ)，(ｃ）側断面図。FIG. 3 is a diagram showing a structure of a thin film transistor, an electrode, and a wiring according to the present invention. (A) Front view, (b), (c) sectional side view.

【図４】本発明の電気光学特性の１例を示す図。ノーマ
リクローズ型の例。FIG. 4 is a diagram showing an example of the electro-optical characteristics of the present invention. Example of normally closed type.

【図５】本発明の電気光学特性の別の例を示す図。ノー
マリオープン型の例。FIG. 5 is a diagram showing another example of the electro-optical characteristics of the present invention. Example of normally open type.

【図６】本発明の電気光学特性の別の例を示す図。ノー
マリクローズ型。FIG. 6 is a diagram showing another example of the electro-optical characteristics of the present invention. Normally closed type.

【図７】本発明の電気光学特性の別の例を示す図。ノー
マリクローズ型。液晶の誘電率異方性が負の場合。FIG. 7 is a diagram showing another example of the electro-optical characteristics of the present invention. Normally closed type. When the dielectric anisotropy of the liquid crystal is negative.

【図８】本発明の電気光学特性のさらに別の例を示す
図。ノーマリクローズ型。FIG. 8 is a view showing still another example of the electro-optical characteristics of the present invention. Normally closed type.

【図９】本発明の駆動波形を示す図。FIG. 9 is a diagram showing a driving waveform according to the present invention.

【図１０】本発明の回路を示す図。FIG. 10 is a diagram showing a circuit of the present invention.

【図１１】本発明の１画素の等価回路を示す図。FIG. 11 is a diagram showing an equivalent circuit of one pixel of the present invention.

【図１２】本発明の別の駆動波形を示す図。走査配線電
極への電圧波形が３値レベルである場合。FIG. 12 is a diagram showing another driving waveform according to the present invention. The case where the voltage waveform to the scanning wiring electrode is a ternary level.

【図１３】本発明表示装置の複数画素の配置を示す図。FIG. 13 is a diagram showing an arrangement of a plurality of pixels of the display device of the present invention.

【図１４】本発明表示装置のブラックマトリクスを含む
複数画素の配置を示す図。FIG. 14 is a diagram showing an arrangement of a plurality of pixels including a black matrix of the display device of the present invention.

【符号の説明】[Explanation of symbols]

１…共通電極（コモン電極）、２…絶縁保護膜、３…信
号電極(ドレイン電極)、４…画素電極（ソース電極）、
５…保護絶縁膜、、６…液晶組成物層中の液晶分子、７
…基板、８…偏光板、９…電界方向、１０…界面上の分
子長軸配向方向（ラビング方向）、１１…偏光板偏光透
過軸方向、１２…走査電極(ゲート電極)、１３…アモル
ファスシリコン、１４…薄膜トランジスタ部、１５…１
画素ピッチ、１６…付加容量素子部、１７…コントロー
ル回路、１８…走査電極駆動回路、１９…信号電極駆動
回路、２０…共通電極駆動回路、２１…表示領域、２２
…遮光層。DESCRIPTION OF SYMBOLS 1 ... Common electrode (common electrode), 2 ... Insulating protective film, 3 ... Signal electrode (drain electrode), 4 ... Pixel electrode (source electrode),
5: protective insulating film, 6: liquid crystal molecules in the liquid crystal composition layer, 7
... Substrate, 8 ... Polarizing plate, 9 ... Electric field direction, 10 ... Direction of molecular long axis alignment on interface (rubbing direction), 11 ... Polarizing plate polarized light transmission axis direction, 12 ... Scanning electrode (gate electrode), 13 ... Amorphous silicon , 14 ... Thin film transistor part, 15 ... 1
Pixel pitch, 16: additional capacitance element section, 17: control circuit, 18: scan electrode drive circuit, 19: signal electrode drive circuit, 20: common electrode drive circuit, 21: display area, 22
... light shielding layer.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平４−96017（ＪＰ，Ａ) 特開 平１−107237（ＪＰ，Ａ) 特公 昭63−21907（ＪＰ，Ｂ１) 特表 平５−505247（ＪＰ，Ａ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) G02F 1/133 550 G09G 3/18 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-96017 (JP, A) JP-A-1-107237 (JP, A) JP-B-63-21907 (JP, B1) 505247 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/133 550 G09G 3/18

Claims (11)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】少なくとも一方が透明な一対の基板，該基
板間に挾持され、配向した誘電率異方性と屈折率異方性
とを有する液晶組成物層，偏光手段，マトリクス状に配
置された複数の画素，各画素ごとに備えられ、画素電
極，信号配線電極及び走査配線電極に接続された薄膜ト
ランジスタ素子，共通電極，前記画素電極と共通電極の
間に電圧信号波形を印加する手段とを有する液晶表示装
置において、 前記画素電極と前記共通電極は、電圧信号波形を印加す
る手段により前記画素電極と前記共通電極との間でか
つ、基板面にほぼ平行に電界を印加するように配置さ
れ、 前記液晶組成物層の配向状態及び前記偏光手段の構成
は、前記画素電極と前記共通電極間に印加される電圧Ｖ
_LCがほぼゼロにおいて明るさがほぼゼロでかつ電圧Ｖ_LC
をゼロから徐々に増大させるに従い実質的に明るさが変
化しない電圧領域をへた後に明るさが増大する、あるい
は電圧Ｖ_LCをゼロから徐々に増大させるに従い明るさが
減少し最小値をとるように設定され、 前記信号配線電極および前記共通電極のそれぞれには走
査配線電極に印加する走査信号波形Ｖ_S に同期をとった
電圧波形Ｖ_D，Ｖ_Cが印加され、前記信号配線電極および
前記共通電極に印加される電圧波形Ｖ_D，Ｖ_Cは前記画素
に印加される実効電圧Ｖ_LCが前記共通電極からの電圧波
形の振幅Ｖ_C がゼロの場合に比べて高くなるように定め
られ、 かつ前記信号配線電極に印加する電圧の波高値を画像情
報に従い変化させることで、前記画素に印加される実効
電圧Ｖ_LCが明るさが最小となる電圧Ｖ_OFF 近傍とそれよ
り明るい状態となる電圧Ｖ_ONとの間で変化するように定
めて駆動され、 前記走査配線電極に少なくとも３値以上の振幅レベルを
有する電圧波形を印加し、走査選択期間には、薄膜トラ
ンジスタ素子の信号配線，画素電極間の抵抗値を著しく
下げるのに十分な高いレベルを有し、かつもっとも高い
レベルのＶ _GH を印加し、非走査選択期間には、共通配線
電極に印加した電圧Ｖ _C の増減に応じて、異なるレベル
の２値以上の電圧（最高値をＶ _GLH ，最低値をＶ _GLL と定
義する）を印加し、走査配線電極と共通電極の間の電位
差を減じたことを特徴とする液晶 表示装置。 1. A liquid crystal composition layer having at least one of a pair of transparent substrates sandwiched between said substrates, having aligned dielectric anisotropy and refractive index anisotropy, polarizing means, and being arranged in a matrix. A plurality of pixels, a thin-film transistor element connected to the pixel electrode, the signal wiring electrode and the scanning wiring electrode, a common electrode, and means for applying a voltage signal waveform between the pixel electrode and the common electrode. In the liquid crystal display device, the pixel electrode and the common electrode are arranged so as to apply an electric field between the pixel electrode and the common electrode and substantially parallel to the substrate surface by means for applying a voltage signal waveform. The alignment state of the liquid crystal composition layer and the configuration of the polarizing means are determined by the voltage V applied between the pixel electrode and the common electrode.
_{When the LC is} almost zero, the brightness is almost zero and the voltage V _LC
As the voltage _VLC gradually increases from zero, the brightness increases after going through a voltage region where the brightness does not substantially change, or as the voltage _VLC gradually increases from zero, the brightness decreases and takes a minimum value. Voltage waveforms V _D and V _C synchronized with the scanning signal waveform V _S applied to the scanning wiring electrode are applied to the signal wiring electrode and the common electrode, respectively. The voltage waveforms V _D and V _C applied to the electrodes are determined so that the effective voltage V _LC applied to the pixel is higher than when the amplitude V _C of the voltage waveform from the common electrode is zero, and By changing the peak value of the voltage applied to the signal wiring electrode in accordance with the image information, the effective voltage _VLC applied to the pixel is in the vicinity of the voltage V _OFF where the brightness becomes minimum, and the voltage V becomes brighter than that. _O Determined is driven to change between a _N, at least three or more values of the amplitude level of the scanning wiring electrode
And a thin-film transistor during the scanning selection period.
The resistance between the signal wiring of the transistor element and the pixel electrode
Have a high enough level to lower and the highest
Level V _GH is applied, and the common wiring is
In response to an increase or a decrease of the voltage V _C applied to the electrodes, different levels
2 or more values of the voltage (the maximum value V _GLH, the minimum value V _GLL the constant of
Is applied, and the potential between the scanning wiring electrode and the common electrode is applied.
A liquid crystal display device characterized by a reduced difference . 【請求項２】前記液晶組成物層内の配向に関して、一方
の基板界面上での液晶分子配向方向角度φ_LC1と他方基
板界面上での液晶分子配向方向角度φ_LC2とが互いに略
平行（φ_LC1≒φ_LC2≡φ_LC）であり、かつ前記液晶組成
物層の厚みｄ及び屈折率異方性Δｎの積ｄ・Δｎが０.
２１μｍから０.３６μｍの間であることを特徴とする
請求項１項に記載の液晶表示装置。2. With respect to the orientation in the liquid crystal composition layer, the liquid crystal molecule orientation angle φ _LC1 on one substrate interface and the liquid crystal molecule orientation angle φ _LC2 on the other substrate interface are substantially parallel to each other (φ _LC1 ≒ _{φ LC2 ≡φ LC)} and is, and the product d · [Delta] n of thickness d and refractive index anisotropy [Delta] n of the liquid crystal composition layer is 0.
The liquid crystal display device according to claim 1, wherein the thickness is between 21 µm and 0.36 µm. 【請求項３】前記液晶組成物層の誘電率異方性が正であ
り、前記界面上の液晶分子の長軸方向と電界方向とのな
す角｜φ_LC｜が４５度を超え９０度未満であり、前記偏
光手段が前記液晶組成物層を挟む一対の偏光板であり、
該一対の偏光板のうちの一方の偏光板Ａの透過軸（或い
は吸収軸）の角度φ_Pとφ_LCとのなす角｜φ_LC−φ_P｜が
２度以下であることを特徴とする請求項２項に記載の液
晶表示装置。3. The liquid crystal composition layer has a positive dielectric anisotropy, and an angle | φ _LC | between a major axis direction of the liquid crystal molecules on the interface and an electric field direction is more than 45 degrees and less than 90 degrees. Wherein the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer,
The angle | φ _LC −φ _P | formed by the angle φ _P and φ _LC of the transmission axis (or absorption axis) of one polarizing plate A of the pair of polarizing plates is 2 degrees or less. The liquid crystal display device according to claim 2. 【請求項４】前記界面上の液晶分子の長軸方向と電界方
向とのなす角｜φ_LC｜が８５度を超え９０度未満であ
り、かつ前記液晶組成物層の厚みｄ及び屈折率異方性Δ
ｎの積ｄ・Δｎが０.２６μｍから０.３６μｍの間であ
ることを特徴とする請求項３項に記載の液晶表示装置。4. An angle | φ _LC | between a major axis direction of liquid crystal molecules on the interface and an electric field direction is more than 85 degrees and less than 90 degrees, and the thickness d of the liquid crystal composition layer and the refractive index difference are different. Isotropic Δ
4. The liquid crystal display device according to claim 3, wherein a product d · Δn of n is between 0.26 μm and 0.36 μm. 【請求項５】前記液晶組成物層の誘電率異方性が正であ
り、前記界面上の液晶分子の長軸方向と電界方向とのな
す角｜φ_LC｜が４５度を超え９０度未満であり、前記偏
光手段が前記液晶組成物層を挟む一対の偏光板であり、
該一対の偏光板のうちの一方の偏光板の透過軸（或いは
吸収軸）の角度φ_P よりも大きく、かつその差｜φ_LC−
φ_P|が２度以上３０度以下であることを特徴とする請求
項２項に記載の液晶表示装置。5. The liquid crystal composition layer has a positive dielectric anisotropy, and an angle | φ _LC | between a major axis direction of liquid crystal molecules and an electric field direction on the interface is more than 45 degrees and less than 90 degrees. Wherein the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer,
The pair of one transmission axis of the polarizing plate of the polarizing plate (or absorption axis) greater than the angle phi _P of, and the difference | phi _LC -
3. The liquid crystal display device according to claim 2, wherein φ _P | is 2 degrees or more and 30 degrees or less. 【請求項６】前記界面上の液晶分子の長軸方向と電界方
向とのなす角｜φ_LC｜が８０度以上９０度未満であり、
角度差|φ_LC−φ_P｜が２度以上１０度以下であることを
特徴とする請求項５項に記載の液晶表示装置。6. An angle | φ _LC | between a major axis direction of liquid crystal molecules and an electric field direction on the interface is 80 degrees or more and less than 90 degrees,
6. The liquid crystal display device according to claim 5, wherein the angle difference | φ _LC −φ _P | is 2 degrees or more and 10 degrees or less. 【請求項７】前記液晶組成物層の誘電率異方性が負であ
り、前記界面上の液晶分子の長軸方向と電界方向とのな
す角｜φ_LC｜が０度を超え４５度未満であり、前記偏光
手段が前記液晶組成物層を挟む一対の偏光板であり、該
一対の偏光板のうちの一方の偏光板の透過軸（或いは吸
収軸）の角度φ_Pとφ_LCとのなす角｜φ_LC−φ_P｜が２度
以下であることを特徴とする請求項２項に記載の液晶表
示装置。7. The liquid crystal composition layer has a negative dielectric anisotropy, and an angle | φ _LC | between a major axis direction of the liquid crystal molecules on the interface and an electric field direction is more than 0 degree and less than 45 degrees. , and the said a pair of polarizing plates polarizing means sandwich the liquid crystal composition layer, of the angle phi _P and phi _LC of the pair of one transmission axis of the polarizing plate of the polarizing plate (or absorption axis) 3. The liquid crystal display device according to claim 2, wherein the angle | φ _LC −φ _P | is 2 degrees or less. 【請求項８】前記界面上の液晶分子の長軸方向と電界方
向とのなす角｜φ_LC｜が０度を超え５度未満であり、か
つ前記液晶組成物層の厚みｄ及び屈折率異方性Δｎの積
ｄ・Δｎが０.２６μｍから０.３６μｍの間であること
を特徴とする請求項７項に記載の液晶表示装置。8. An angle | φ _LC | formed between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is more than 0 degree and less than 5 degrees, and the thickness d and the refractive index difference of the liquid crystal composition layer are different. The liquid crystal display device according to claim 7, wherein a product d · Δn of anisotropy Δn is between 0.26 μm and 0.36 μm. 【請求項９】前記液晶組成物層の誘電率異方性が負であ
り、前記界面上の液晶分子の長軸方向と電界方向とのな
す角｜φ_LC｜が０度を超え４５度未満であり、前記偏光
手段が前記液晶組成物層を挟む一対の偏光板であり、該
一対の偏光板のうちの一方の偏光板の透過軸（或いは吸
収軸）の角度φ_P よりも小さく、かつその差｜φ_LC−φ
_P|が２度以上３０度以下であることを特徴とする請求項
２項に記載の液晶表示装置。9. The liquid crystal composition layer has a negative dielectric anisotropy, and an angle | φ _LC | between a major axis direction of liquid crystal molecules and an electric field direction on the interface is more than 0 degree and less than 45 degrees. Wherein the polarizing means is a pair of polarizing plates sandwiching the liquid crystal composition layer, and is smaller than an angle φ _P of a transmission axis (or absorption axis) of one of the pair of polarizing plates, and The difference | φ _LC −φ
3. The liquid crystal display device according to claim 2, wherein _P | is not less than 2 degrees and not more than 30 degrees. 【請求項１０】前記界面上の液晶分子の長軸方向と電界
方向とのなす角｜φ_LC｜が０度を超え１０度未満であ
り、前記角度差｜φ_LC−φ_P|が２度以上１０度以下であ
ることを特徴とする請求項９項に記載の液晶表示装置。10. An angle | φ _LC | formed between the major axis direction of the liquid crystal molecules on the interface and the electric field direction is more than 0 degree and less than 10 degrees, and the angle difference | φ _LC −φ _P | is 2 degrees. 10. The liquid crystal display device according to claim 9, wherein the angle is not less than 10 degrees. 【請求項１１】11. 前記複数の画素のそれぞれの画素においIn each of the plurality of pixels,
て、hand, 前記共通電極は２本の共通電極により構成されており、The common electrode is constituted by two common electrodes, 前記画素電極は、前記２本の共通電極間に配置された構The pixel electrode is arranged between the two common electrodes.
成である請求項１の液晶表示装置。The liquid crystal display device according to claim 1, wherein