JP3616973B2 - Nematic liquid crystal drive method - Google Patents
Nematic liquid crystal drive method Download PDFInfo
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- JP3616973B2 JP3616973B2 JP28238195A JP28238195A JP3616973B2 JP 3616973 B2 JP3616973 B2 JP 3616973B2 JP 28238195 A JP28238195 A JP 28238195A JP 28238195 A JP28238195 A JP 28238195A JP 3616973 B2 JP3616973 B2 JP 3616973B2
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- Prior art keywords
- liquid crystal
- nematic liquid
- color
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- color frame
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Description
【0001】
【発明の属する技術分野】
本発明は液晶の駆動方法、殊にネマテック液晶の駆動方法に関するものである。
【0002】
【従来の技術】
ネマテック液晶の分子は多くが細長い分子でありそれらの長軸方向をそろえて配向しているが、電界を印加した場合、3つの弾性係数の大きさおよび相互の比率に従って変形を生じ、電界を取り去ると元の配向状態に回復する、という性質を有している。
【0003】
そして、このような性質を有するネマテック液晶と偏光板とを組み合わせた液晶表示装置が知られている。
【0004】
【発明が解決しようとする課題】
ところが、例えばSTN型の液晶表示素子の応答速度は200〜300msと遅く、動画映像を表示するにはコントラストが得られず困難であるばかりかコンピュータなどにおける文字表示においてもマウスの動作に追随できず、更に走査線の多い大容量表示を困難にする、などの問題がある。
【0005】
本発明が解決しようとする課題は、従来から用いられているTN型やSTN型のネマテック液晶の応答速度を高め、従来困難であった動画映像の表示や走査線の多い大容量表示などを可能にする、即ち、応答速度が速いネマテック液晶の駆動方法を提供するものである。
【0006】
【課題を解決するための手段】
本発明は、上記目的を達成するため、ネマテック液晶素子と、R,G,B3色の光源を有するバックライトとを備え、一映像色合成フレーム毎に前記バックライトのR,G,B各色の光源を等周期で順次点灯させるとともに、前記R,G,B各色の光源の点灯周期である色フレームに対応させて所定ドット位置の前記ネマテック液晶素子をオン、オフ駆動したときに生じる視覚による残像現象により任意の色表示を得るカラー液晶表示装置において、前記ネマテック液晶素子を前記色フレームの周期よりも短い時間間隔で階調に応じてオン、オフ駆動し、前記ネマテック液晶素子の変化に対する積算の量が、段階的に調整されて前記色フレーム毎に所望の階調表示を行うことを特徴とするネマテック液晶の駆動方法を提供する。
【0007】
多数回の繰り返し電圧により電圧印加を行うと、図1に示すようにオン信号とオフ信号の周期の時間間隔が短くなり、ネマテック液晶のオン・オフ動作での積分/微分動作の関係から優れた動作レスポンスを発揮する。
【0008】
【実施例】
次に本発明の実施例を比較例とともに表1に示す。
【0009】
【表1】
【0010】
表1はSTN型のネマテック液晶素子に25μS周期で電圧を繰り返し印加した場合(実施例1)および250μS周期で電圧を繰り返し印加した場合(実施例2)更に連続的に電圧を印加した場合(比較例)における0N・0FF応答時間の測定値を示したものであり、例えば、実施例1における0N・0FF応答時間は6mSで比較例である従来の駆動方式の50倍の速度で応答することが判る。
【0011】
次に、本発明の利用例として、本発明をカラー液晶表示装置について用いた場合について説明する。
【0012】
本発明を利用したカラー液晶表示装置は、図2に示すようにTNモード型の液晶表示ディスプレィ1と、R,G,B三色管からなるバックライト2と、これらの液晶表示ディスプレィ1とバックライト2とを制御する駆動回路(図示せず)とから構成される。
【0013】
また、TNモード型の液晶表示ディスプレィ1は従来一般に製造されている透過型のTNモード型の液晶表示ディスプレィと同様のものをそのまま使用することが可能であり、下層から順に偏光板11,ガラス基板12,電子回路13,液晶表示素子14および表面カバー15を順に積層したものである。
【0014】
バックライト2は、前記液晶表示ディスプレィ1における偏光板11の下面に配置された導光板21とこの一方の側面に配置されたR(レッド)管22,G(グリーン)管23,B(ブルー)管24とから構成される。
【0015】
そして、図3に示すように図示しない駆動回路により一映像色合成フレーム(例えば40Hz程度の周期)毎に前記バックライトのR,G,B各管22,23,24を等周期(例えば120Hz程度の周期)で順次点灯させるとともに、R,G,B各管22,23,24の点灯周期(色フレーム)に対応させて所定ドット位置のTNモード型の液晶表示素子14をオン、オフ駆動させたときに生じる視覚による残像現象により任意の色表示を得るものである。
【0016】
そして、液晶表示素子14の駆動を、本発明を用いて、例えば繰り返しの電圧印加(例えば40KHz(25μS)程度の周期)により液晶表示素子の変化に対する積算の量を調整するように駆動させる。
【0017】
このときのタイミングチャートを図4に示す。
【0018】
図4に示したタイミングチャートにおいて1〜256枚の間で任意の階調を設定することができ、表示階調は図5に示すように、画像情報に、階調回数を持たせて、最小階調での繰り返し回数に、階調回数を掛けた回数だけ表示動作を行うことにより、液晶表示素子の変化に対する積算の量が、段階的に調整されて、変化量を調整することができる。ティック液晶の駆動方法を提供する。
【0019】
このように本発明である繰り返しの電圧印加を行うと、液晶表示素子11のドット位置に対するオン信号とオフ信号の周期の時間間隔が短くなり、液晶表示素子のオン・オフ動作での積分/微分動作の関係から動作レスポンスに優れたオン動作(積分動作)を短い時間で多数回数、積算する表示をすることになり、前記R,G,B各管22,23,24の点灯周期(色フレーム)毎に変化する表示情報に対応可能な液晶表示素子の動作速度が得られるものである。
【0020】
また、液晶表示素子11のオンからオフへの切り替わりにおいて色が混ざることを防止するために各サブフレームの間にR,G,B各管22,23,24の
いずれもが点灯しない時間を設けるとよい。
【0021】
尚、この液晶表示装置は本発明の利用例を示したものであり、本発明が駆動時間の短縮を必要とする他の用途に用いることができることは云うまでもない。
【0022】
また、本発明は前記実施例から判るように電圧印加の繰り返し周期を変化させることにより異なる0N・0FF応答時間を得ることが可能であり、繰り返し周期を選択することにより所望の0N・0FF応答時間を得ることが可能である。
【0023】
【発明の効果】
以上のように本発明は、ネマテック液晶素子に多数回の繰り返し電圧により印加を行うことによりオン信号とオフ信号における周期の時間間隔が短くなり、優れた動作レスポンスを発揮させることができる。
【0024】
従って、例えば動画映像表示するためのカラー液晶表示装置のように従来ネマテック液晶素子を用いることが困難であった用途にネマテック液晶素子を用いることができるものである。
【0025】
殊に、TN型、STN型などのネマテック液晶素子は他のTFT液晶素子に比べて駆動方法が簡単で価格も安いため本発明はきわめて有効である。
【図面の簡単な説明】
【図1】本発明および従来例における液晶素子の動作状態を示す状態図である。
【図2】本発明を用いた液晶表示装置の概略図である。
【図3】図2に示した液晶表示装置におけるカラー表示の原理を示す説明図である。
【図4】図2に示した液晶表示装置における好ましいタイミングチャートである。
【図5】図4に示したタイミングチャートにおける表示諧調の調整状態を示す説明図である。
【符号の説明】
1 液晶表示ディスプレィ
2 バックライト
22 R管
23 G管
24 B管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal driving method, and more particularly to a nematic liquid crystal driving method.
[0002]
[Prior art]
Many of the nematic liquid crystal molecules are elongated and aligned along the long axis direction, but when an electric field is applied, deformation occurs according to the magnitude of the three elastic coefficients and the ratio between them, removing the electric field. And the original orientation state is restored.
[0003]
And the liquid crystal display device which combined the nematic liquid crystal which has such a property, and a polarizing plate is known.
[0004]
[Problems to be solved by the invention]
However, for example, the response speed of the STN type liquid crystal display element is as slow as 200 to 300 ms, and it is difficult to display a moving image, and it is difficult to follow the operation of the mouse even in character display on a computer or the like. In addition, there are problems such as making it difficult to display a large volume of scanning lines.
[0005]
The problem to be solved by the present invention is to increase the response speed of TN-type and STN-type nematic liquid crystal that has been used in the past, and to display moving images and large-capacity displays with many scanning lines, which were difficult in the past. In other words, the present invention provides a driving method of nematic liquid crystal having a high response speed.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a nematic liquid crystal element and a backlight having light sources of R, G, and B colors, and each of the R, G, and B colors of the backlight for each video color synthesis frame. Visual afterimages generated when the light source is sequentially turned on at equal intervals and the nematic liquid crystal element at a predetermined dot position is driven on and off in correspondence with the color frame that is the lighting cycle of the light sources of the R, G, and B colors. in the color liquid crystal display device for obtaining any color displayed by the phenomenon, and the on and off drive according to prior Symbol nematic TEC liquid crystal element gradation time interval shorter than the period of the color frame, the change in the nematic liquid crystal element the amount of accumulated relative provides a nematic TEC liquid crystal driving method which is adjusted stepwise and performing desired gradation display for each of the color frame.
[0007]
When voltage is applied with a large number of repetitive voltages, the time interval between the ON signal and OFF signal periods is shortened as shown in FIG. 1, which is excellent from the relationship of integration / differentiation operation in the ON / OFF operation of the nematic liquid crystal. Demonstrate operational response.
[0008]
【Example】
Next, examples of the present invention are shown in Table 1 together with comparative examples.
[0009]
[Table 1]
[0010]
Table 1 shows a case where a voltage was repeatedly applied to a STN type nematic liquid crystal element at a cycle of 25 μS (Example 1) and a case where a voltage was repeatedly applied at a cycle of 250 μS (Example 2). The measured value of 0N · 0FF response time in Example) is shown. For example, the response time of 0N · 0FF in Example 1 is 6 mS, and the response can be made at a speed 50 times that of the conventional driving method as a comparative example. I understand.
[0011]
Next, a case where the present invention is used for a color liquid crystal display device will be described as an application example of the present invention.
[0012]
As shown in FIG. 2, a color liquid crystal display device using the present invention includes a TN mode type
[0013]
The TN mode type
[0014]
The backlight 2 includes a light guide plate 21 disposed on the lower surface of the polarizing plate 11 in the
[0015]
Then, as shown in FIG. 3, the R, G,
[0016]
Then, the liquid crystal display element 14 is driven to adjust the amount of integration with respect to the change of the liquid crystal display element by, for example, repetitive voltage application (for example, a cycle of about 40 KHz (25 μS)) using the present invention.
[0017]
A timing chart at this time is shown in FIG.
[0018]
In the timing chart shown in FIG. 4 can be set any gradation between 1 to 256 sheets, the display gradation, as shown in FIG. 5, the image information and to have a gradation number, the minimum the number of repetitions in the gradation, by just print operation times obtained by multiplying the gradation number, the amount of accumulation with respect to the change of the liquid crystal display element, is adjusted stepwise, it is possible to adjust the amount of change. A tick liquid crystal driving method is provided.
[0019]
As described above, when the repetitive voltage application according to the present invention is performed, the time interval of the cycle of the on signal and the off signal with respect to the dot position of the liquid crystal display element 11 is shortened, and the integration / differentiation in the on / off operation of the liquid crystal display element. The ON operation (integration operation) excellent in operation response due to the operation relationship is displayed many times in a short time, and the lighting cycle (color frame) of each of the R, G,
[0020]
In addition, in order to prevent the colors from being mixed when the liquid crystal display element 11 is switched from on to off, a period of time during which none of the R, G,
[0021]
Note that this liquid crystal display device shows an example of use of the present invention, and it goes without saying that the present invention can be used for other applications that require a reduction in driving time.
[0022]
Further, as can be seen from the above embodiments, the present invention can obtain different 0N · 0FF response times by changing the repetition period of voltage application, and a desired 0N · 0FF response time by selecting the repetition period. It is possible to obtain
[0023]
【The invention's effect】
As described above, according to the present invention, by applying the nematic liquid crystal element with a repetitive voltage many times, the time interval of the cycle between the on signal and the off signal is shortened, and an excellent operation response can be exhibited.
[0024]
Therefore, nematic liquid crystal elements can be used for applications where it has been difficult to use conventional nematic liquid crystal elements, such as color liquid crystal display devices for displaying moving images.
[0025]
Particularly, nematic liquid crystal elements such as TN type and STN type are very effective because the driving method is simpler and the price is lower than other TFT liquid crystal elements.
[Brief description of the drawings]
FIG. 1 is a state diagram showing an operation state of a liquid crystal element in the present invention and a conventional example.
FIG. 2 is a schematic view of a liquid crystal display device using the present invention.
3 is an explanatory diagram showing the principle of color display in the liquid crystal display device shown in FIG. 2. FIG.
FIG. 4 is a preferred timing chart in the liquid crystal display device shown in FIG.
FIG. 5 is an explanatory diagram showing a display gradation adjustment state in the timing chart shown in FIG. 4;
[Explanation of symbols]
1 Liquid crystal display 2 Backlight 22 R tube 23 G tube 24 B tube
Claims (3)
前記ネマテック液晶素子を前記色フレームの周期よりも短い時間間隔で階調に応じてオン、オフ駆動し、前記ネマテック液晶素子の変化に対する積算の量が、段階的に調整されて前記色フレーム毎に所望の階調表示を行うことを特徴とするネマテック液晶の駆動方法。A nematic liquid crystal element and a backlight having light sources of three colors R, G, B, and sequentially turning on the light sources of the R, G, B colors of the backlight for each image color synthesis frame at regular intervals; A color liquid crystal display that obtains an arbitrary color display by a visual afterimage phenomenon that occurs when the nematic liquid crystal element at a predetermined dot position is driven on and off in correspondence with a color frame that is a lighting cycle of light sources of R, G, and B colors. In the device
On the nematic TEC liquid crystal device according to the tone at a time interval shorter than the period of the color frame, and off-drive, the amount of accumulation with respect to a change in the nematic liquid crystal element, the color frame is adjusted stepwise A nematic liquid crystal driving method, wherein a desired gradation display is performed every time.
Priority Applications (1)
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JP28238195A JP3616973B2 (en) | 1995-10-05 | 1995-10-05 | Nematic liquid crystal drive method |
Applications Claiming Priority (1)
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JP28238195A JP3616973B2 (en) | 1995-10-05 | 1995-10-05 | Nematic liquid crystal drive method |
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JP2004291736A Division JP2005025226A (en) | 2004-10-04 | 2004-10-04 | Method for driving nematic liquid crystal |
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JPH09265073A JPH09265073A (en) | 1997-10-07 |
JP3616973B2 true JP3616973B2 (en) | 2005-02-02 |
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JP28238195A Expired - Lifetime JP3616973B2 (en) | 1995-10-05 | 1995-10-05 | Nematic liquid crystal drive method |
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JP3247643B2 (en) | 1997-09-10 | 2002-01-21 | インターナショナル・ビジネス・マシーンズ・コーポレーション | Liquid crystal display device |
JP3644672B2 (en) | 1999-07-09 | 2005-05-11 | シャープ株式会社 | Display device and driving method thereof |
KR101213810B1 (en) * | 2005-12-27 | 2012-12-18 | 엘지디스플레이 주식회사 | Apparatus and method for driving LCD |
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