JP2007178738A - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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JP2007178738A
JP2007178738A JP2005377203A JP2005377203A JP2007178738A JP 2007178738 A JP2007178738 A JP 2007178738A JP 2005377203 A JP2005377203 A JP 2005377203A JP 2005377203 A JP2005377203 A JP 2005377203A JP 2007178738 A JP2007178738 A JP 2007178738A
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liquid crystal
viewing angle
angle control
display device
pixel
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JP4976691B2 (en
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Kazuyoshi Nagayama
和由 永山
Yuichi Momoi
優一 桃井
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LG Display Co Ltd
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LG Philips LCD Co Ltd
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Priority to KR1020060041802A priority patent/KR101222970B1/en
Priority to US11/646,595 priority patent/US8233124B2/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G02F1/134372—Electrodes characterised by their geometrical arrangement for fringe field switching [FFS] where the common electrode is not patterned

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Liquid Crystal (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device whose viewing angle can vertically and horizontally be adjusted while display unevenness is suppressed without the need to provide a special liquid crystal panel. <P>SOLUTION: The liquid crystal display device which has a display screen composed of an assembly of pixels of R, G, and B brought under alignment control of an FFS system so that liquid crystal molecules may tilt is further equipped with a a viewing control pixel 20 which is brought under alignment control so that liquid crystal molecules may tilt vertically or horizontally and applied with a batch ON/OFF voltage signal within the display screen without switching by pixels. Thus, the liquid crystal display device is equipped with the viewing angle control pixel 20 independent of the pixels of R, G, and B and the viewing angle can vertically and horizontally be adjusted. Further, a voltage signal applied to the viewing angle control pixel is adjusted to suppress display unevenness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、視野角制御を可能とする液晶表示装置に関し、特に、ＦＦＳ（Ｆｒｉｎｇｅ Ｆｉｅｌｄ Ｓｗｉｔｃｈｉｎｇ：フリンジフィールドスイッチング）方式を用いた液晶表示装置に関する。   The present invention relates to a liquid crystal display device that enables viewing angle control, and more particularly, to a liquid crystal display device using a FFS (Fringe Field Switching) method.

液晶表示装置、特にＴＦＴ（Ｔｈｉｎ Ｆｉｌｍ Ｔｒａｎｓｉｓｔｏｒ：薄膜トランジスタ）を用いた液晶表示装置が、広く携帯電話から大型テレビにまで採用されている。このような中で、複数人による視認を考慮した場合には、正面以外の視野からも表示内容を視認できる広視野角を有する液晶表示装置が望まれている。   2. Description of the Related Art Liquid crystal display devices, particularly liquid crystal display devices using TFTs (Thin Film Transistors), are widely used in mobile phones and large-sized televisions. Under such circumstances, when viewing by a plurality of people is taken into consideration, a liquid crystal display device having a wide viewing angle capable of visually recognizing display contents from a field of view other than the front is desired.

図８は、秘匿モードを有する従来の液晶表示装置の説明図である。このような背景のもとに、その一例として、図８に示すような秘匿モードを有するディスプレイが提案されている（例えば、特許文献１参照）。図８において、液晶パネルを裏側から照らすバックライトとしては、指向性の強いものが使用されている。そして、通常の液晶パネルとこの指向性バックライトとの間に、散乱状態および非散乱状態を切り替えられる、例えば、ポリマー分散型液晶パネル（散乱非散乱スイッチ層）が設けられている。   FIG. 8 is an explanatory diagram of a conventional liquid crystal display device having a secret mode. Under such background, as an example, a display having a secret mode as shown in FIG. 8 has been proposed (see, for example, Patent Document 1). In FIG. 8, a backlight having high directivity is used as a backlight for illuminating the liquid crystal panel from the back side. For example, a polymer-dispersed liquid crystal panel (scattering non-scattering switch layer) that can switch between a scattering state and a non-scattering state is provided between the normal liquid crystal panel and the directional backlight.

散乱層が非散乱状態の場合には、バックライトからの光は、正面にしか照射されないため、斜めからは表示を見ることができない。一方、散乱層が散乱状態の場合には、バックライトの光は、斜め方向にも照射されるため、斜めから表示を見ることができ、表示を複数人で共有することができる。この場合には、通常の液晶パネルとは別に、特別な液晶パネルを設けることが必要であるため、高価になってしまうという問題が生じていた。   When the scattering layer is in a non-scattering state, the light from the backlight is irradiated only on the front side, so that the display cannot be seen from an oblique direction. On the other hand, when the scattering layer is in a scattering state, the light from the backlight is also irradiated in an oblique direction, so that the display can be seen from an oblique direction, and the display can be shared by a plurality of people. In this case, since it is necessary to provide a special liquid crystal panel in addition to the normal liquid crystal panel, there has been a problem that it becomes expensive.

次に、コモン電極の形状をくの字状にすることにより、視野角の改善を図った従来のＦＦＳ方式の液晶表示装置について説明する。図９は、従来のＦＦＳ方式の液晶表示装置のＲＧＢ各画素の平面図である。さらに、図１０は、従来のＦＦＳ方式の液晶表示装置の電圧印加による液晶分子の動作の説明図である。   Next, a conventional FFS type liquid crystal display device in which the viewing angle is improved by making the shape of the common electrode a square shape will be described. FIG. 9 is a plan view of RGB pixels of a conventional FFS type liquid crystal display device. Further, FIG. 10 is an explanatory diagram of the operation of liquid crystal molecules by voltage application in a conventional FFS type liquid crystal display device.

図９に示すように、この液晶表示装置においては、液晶の倒れる向きを規定するために、くの字状のコモン電極が形成されている。そして、液晶分子は、電圧無印加状態では、図１０（ａ）に示すように、垂直方向を向いている。一方、液晶分子は、電圧印加状態では、図１０（ｂ）に示すように、コモン電極による斜め電界の影響で決められた方向、すなわち、コモン電極の伸びる方向と垂直な方向に倒れる。これにより、くの字と対応する２方向に液晶を倒すことが可能となり、良好な視野角を持つ液晶表示装置が実現される。   As shown in FIG. 9, in this liquid crystal display device, a V-shaped common electrode is formed to define the direction in which the liquid crystal falls. The liquid crystal molecules are oriented in the vertical direction as shown in FIG. 10A when no voltage is applied. On the other hand, as shown in FIG. 10B, the liquid crystal molecules fall in a direction determined by the influence of an oblique electric field by the common electrode, that is, a direction perpendicular to the direction in which the common electrode extends, as shown in FIG. As a result, the liquid crystal can be tilted in two directions corresponding to the character shape, and a liquid crystal display device having a good viewing angle is realized.

特開平５−７２５２９号公報（第１頁、図１）JP-A-5-72529 (first page, FIG. 1)

しかしながら、従来の液晶表示装置にあっては、次のような課題がある。コモン電極をくの字形状とすることにより、特定の方向の視認性は改善されるものの、必要に応じて秘匿性を持たせるように切り替えることはできなかった。   However, the conventional liquid crystal display device has the following problems. Although the visibility in a specific direction is improved by forming the common electrode in the shape of a letter, it cannot be switched to provide confidentiality as necessary.

本発明は上述のような課題を解決するためになされたもので、特別な液晶パネルを設ける必要がなく、表示むらを抑えた上で、上下左右方向に視野角調整を行うことのできる液晶表示装置を得ることを目的とする。   The present invention has been made to solve the above-described problems, and it is not necessary to provide a special liquid crystal panel, and a liquid crystal display capable of adjusting the viewing angle in the vertical and horizontal directions while suppressing display unevenness. The object is to obtain a device.

本発明に係る液晶表示装置は、ＦＦＳ方式により液晶分子が傾くように配向制御されたＲＧＢの各画素の集合からなる表示画面を有する液晶表示装置であって、上下方位あるいは左右方位に液晶分子が傾くように配向制御され、画素ごとにスイッチングすることなしに前記表示画面内で一括のＯＮ／ＯＦＦ電圧信号が印加される視野角制御画素をさらに備えるものである。   The liquid crystal display device according to the present invention is a liquid crystal display device having a display screen composed of a set of RGB pixels whose orientation is controlled so that the liquid crystal molecules are tilted by the FFS method. The display device further includes a viewing angle control pixel that is controlled to be tilted and to which a collective ON / OFF voltage signal is applied in the display screen without switching pixel by pixel.

本発明によれば、ＦＦＳ方式により液晶分子が傾くように配向制御されたＲＧＢの各画素とともに、上下方位あるいは左右方位に液晶分子が傾くように配向制御され、画素ごとのスイッチング回路を有しない視野角制御画素をさらに形成することにより、特別な液晶パネルを設ける必要がなく、表示むらを抑えた上で、上下左右方向に視野角調整を行うことのできる液晶表示装置を得ることができる。   According to the present invention, together with the RGB pixels whose orientation is controlled so that the liquid crystal molecules are tilted by the FFS method, the orientation is controlled so that the liquid crystal molecules are tilted in the vertical direction or the horizontal direction, and the field of view does not have a switching circuit for each pixel By further forming the angle control pixel, it is not necessary to provide a special liquid crystal panel, and a liquid crystal display device capable of adjusting the viewing angle in the vertical and horizontal directions while suppressing display unevenness can be obtained.

以下、本発明の液晶表示装置の好適な実施の形態につき図面を用いて説明する。   Hereinafter, preferred embodiments of a liquid crystal display device of the present invention will be described with reference to the drawings.

実施の形態１．
図１は、本発明の実施の形態１における液晶表示装置のＲＧＢ各画素および視野角制御画素の平面図である。図１におけるＲＧＢそれぞれの画素は、画素電極とコモン電極１１とを備えている。各画素に設けられたこのコモン電極１１は、くの字状を有している。 Embodiment 1 FIG.
FIG. 1 is a plan view of each RGB pixel and viewing angle control pixel of the liquid crystal display device according to Embodiment 1 of the present invention. Each RGB pixel in FIG. 1 includes a pixel electrode and a common electrode 11. The common electrode 11 provided in each pixel has a dogleg shape.

また、本発明の液晶表示装置は、ＲＧＢ画素とは別に、視野角の制御を行うための視野角制御画素２０をさらに有している。この視野角制御画素２０は、上下方位あるいは左右方位に液晶分子が傾くように配向制御され、ＲＧＢ画素とは別個の視野角制御線（図示せず）を介して制御電圧が印加される。そして、視野角制御画素２０内には、左右方位のコモン電極２１ａあるいは上下方向のコモン電極２１ｂのいずれか一方が存在している。   The liquid crystal display device of the present invention further includes a viewing angle control pixel 20 for controlling the viewing angle, in addition to the RGB pixels. The viewing angle control pixel 20 is orientation controlled so that liquid crystal molecules are tilted in the vertical direction or the horizontal direction, and a control voltage is applied via a viewing angle control line (not shown) separate from the RGB pixels. In the viewing angle control pixel 20, either the left / right common electrode 21a or the vertical common electrode 21b is present.

図１においては、左右方位のコモン電極２１ａを有している視野角制御画素２０を示している。視野角制御線を介してこの視野角制御画素２０に制御電圧を印加することにより、前後方向あるいは左右方向に液晶分子を倒せることとなり、視野角制御が可能となる。   In FIG. 1, a viewing angle control pixel 20 having a common electrode 21a in the horizontal direction is shown. By applying a control voltage to the viewing angle control pixel 20 via the viewing angle control line, the liquid crystal molecules can be tilted in the front-rear direction or the left-right direction, and the viewing angle can be controlled.

視野角制御画素２０は、ＲＧＢ画素とは別個の視野角制御線を介して印加電圧が供給される。そして、視野角制御画素２０用の独立コモン線である視野角制御線を透明電極で形成することにより、開口率を大きく取れるメリットが得られる。また、コモン線が独立していることから、視野角制御画素２０の印加電圧を任意の波形として入力することが可能となる。   The applied voltage is supplied to the viewing angle control pixel 20 via a viewing angle control line separate from the RGB pixels. Then, by forming a viewing angle control line, which is an independent common line for the viewing angle control pixel 20, with a transparent electrode, an advantage that a large aperture ratio can be obtained can be obtained. Further, since the common lines are independent, it is possible to input the voltage applied to the viewing angle control pixel 20 as an arbitrary waveform.

また、視野角制御画素２０は、表示には直接寄与せず、表示情報を見にくくするために寄与するものである。従って、この視野角制御画素２０に対向するカラーフィルタ基板側には、着色層を設ける必要がないというメリットもある。   The viewing angle control pixel 20 does not contribute directly to the display but contributes to make it difficult to see the display information. Therefore, there is an advantage that it is not necessary to provide a colored layer on the color filter substrate side facing the viewing angle control pixel 20.

次に、視野角制御画素２０における電圧の印加／無印加状態での液晶分子の動作について説明する。図２は、本発明の実施の形態１における左右方位のコモン電極２１ａを有する視野角制御画素２０での液晶分子の動作の説明図である。   Next, the operation of the liquid crystal molecules in the viewing angle control pixel 20 in the voltage application / non-application state will be described. FIG. 2 is an explanatory diagram of the operation of liquid crystal molecules in the viewing angle control pixel 20 having the left and right common electrodes 21a in the first embodiment of the present invention.

左右方位のコモン電極２１ａを有する視野角制御画素２０において、電圧が印加されていない場合には、図２（ａ）に示すように、液晶は、水平の状態である。従って、視野角制御画素２０の表示は、黒いままとなり、全体の表示には影響を与えない。これは、正面、上下左右、斜め視角においても同様で、ＲＧＢ画素による表示自体は、全く自然に使えることとなる。   In the viewing angle control pixel 20 having the left and right common electrodes 21a, when no voltage is applied, as shown in FIG. 2A, the liquid crystal is in a horizontal state. Therefore, the display of the viewing angle control pixel 20 remains black and does not affect the entire display. The same applies to the front, top / bottom / left / right, and oblique viewing angles, and the display itself using RGB pixels can be used quite naturally.

一方、左右方位のコモン電極２１ａを有する視野角制御画素２０において、電圧が印加された場合には、図２（ｂ）に示すように、液晶分子は、コモン電極の中央部およびコモン電極間の中央部で、垂直に立った状態となる。従って、左右方向からみた場合には、左右方位のコモン電極２１ａが入った部分は、明るく光が抜けてくることとなる。逆に、上下方向から見た場合には、左右方位のコモン電極２１ａが入った部分は、光が漏れてこないこととなる。   On the other hand, in the viewing angle control pixel 20 having the common electrode 21a in the horizontal direction, when a voltage is applied, as shown in FIG. 2B, the liquid crystal molecules are separated between the central portion of the common electrode and the common electrode. In the center, it stands upright. Accordingly, when viewed from the left-right direction, the portion where the common electrode 21a in the left-right direction is inserted brightly emits light. On the contrary, when viewed from above and below, light does not leak from the portion where the common electrode 21a in the horizontal direction is inserted.

これに対して、上下方位のコモン電極２１ｂを有する視野角制御画素２０において、電圧が印加された場合には、図２（ｂ）とは９０度異なる方向において、液晶分子は、コモン電極の中央部およびコモン電極間の中央部で、垂直に立った状態となる。従って、左右方向からみた場合には、上下方位のコモン電極２１ｂが入った部分からは、光が漏れてこないこととなる。逆に、上下方向から見た場合には、上下方位のコモン電極２１ｂが入った部分は、明るく光が抜けてくることとなる。   On the other hand, in the viewing angle control pixel 20 having the common electrode 21b in the vertical direction, when a voltage is applied, the liquid crystal molecules are aligned at the center of the common electrode in a direction different by 90 degrees from FIG. In a central portion between the electrode and the common electrode, it stands vertically. Therefore, when viewed from the left-right direction, light does not leak from the portion where the vertical common electrode 21b is inserted. On the other hand, when viewed from above and below, light enters the portion where the common electrode 21b in the up-and-down direction enters and brightly passes through.

その結果、視野角制御画素２０に電圧を印加した状態において、左右方向からの視野に対しては、左右方位のコモン電極２１ａを有する視野角制御領域は白、上下方位のコモン電極２１ｂを有する視野角制御領域は黒として認識されることとなる。逆に、上下方向からの視野に対しては、左右方位のコモン電極２１ａを有する視野角制御領域は黒、上下方位のコモン電極２１ｂを有する視野角制御領域は白として認識されることとなる。   As a result, in a state where a voltage is applied to the viewing angle control pixel 20, the viewing angle control region having the left and right common electrodes 21a is white and the viewing angle having the common electrodes 21b in the vertical direction with respect to the viewing direction from the left and right directions. The corner control area is recognized as black. On the other hand, for the visual field from the vertical direction, the viewing angle control area having the left and right common electrodes 21a is recognized as black, and the viewing angle control area having the vertical common electrodes 21b is recognized as white.

そして、これらのパターンがＲＧＢ画素による通常の表示パターンに重なることとなり、それぞれの画素において、左右方向および上下方向からパターンを見た場合には、何が書いてあるのか分からなくすることができ、表示情報に秘匿性を持たせることができる。   And these patterns will overlap with the normal display pattern by RGB pixels, and in each pixel, when looking at the pattern from the left and right direction and the up and down direction, it is not possible to understand what is written, The display information can be kept confidential.

上述のように、それぞれのＲＧＢ画素に対応する視野角制御画素２０には、左右方位のコモン電極２１ａを有する画素、あるいは上下方位のコモン電極２１ｂを有する画素の何れか一方が存在することから、視野角制御画素２０に電圧を印加することにより、左右方向および上下方向からの両方の視野に対する表示を白くすることができる。これにより、正面以外からの視野に対して秘匿性を有する表示が可能となる。   As described above, the viewing angle control pixel 20 corresponding to each RGB pixel includes either a pixel having the common electrode 21a in the horizontal direction or a pixel having the common electrode 21b in the vertical direction. By applying a voltage to the viewing angle control pixel 20, it is possible to whiten the display for both the left and right visual fields. Thereby, the display which has secrecy with respect to the visual field from other than the front is attained.

図３は、本発明の実施の形態１における視野角制御画素２０の電圧印加による視野角依存の輝度分布を示す図であり、視野角制御画素が左右方位のコモン電極２１ａを有している場合を示している。視野角制御画素２０に電圧が印加されていない場合には、正面と上下左右からの斜め方向ともに、輝度は黒画面に相当する輝度になる。一方、視野角制御画素２０に電圧が印加された場合には、正面は黒であるが、左右からの斜め方向は光が抜けてきて明るくなる。   FIG. 3 is a diagram showing a luminance distribution depending on the viewing angle by applying a voltage to the viewing angle control pixel 20 according to the first embodiment of the present invention, where the viewing angle control pixel has a common electrode 21a in the horizontal direction. Is shown. When no voltage is applied to the viewing angle control pixel 20, the luminance is equivalent to that of a black screen in both the front and the diagonal directions from the top, bottom, left, and right. On the other hand, when a voltage is applied to the viewing angle control pixel 20, the front is black, but light is extracted and brightened in an oblique direction from the left and right.

この結果、左右方位の斜め方向のみに光が漏れてくるので、左右方位の斜め方向から見ると表示されている画面を認識しづらくなり、情報に秘匿性を持たせることが可能となる。   As a result, since light leaks only in the diagonal direction of the left and right direction, it is difficult to recognize the displayed screen when viewed from the diagonal direction of the left and right direction, and it is possible to make information confidential.

図４は、本発明の実施の形態１における液晶表示装置の視野角制御画素近傍の平面図である。視野角制御画素２０への電圧印加は、スイッチング素子を介して行うことができる。また、図５は、本発明の実施の形態１における液晶表示装置の視野角制御画素近傍の別の平面図である。本発明における視野角制御画素２０は、画素ごとにスイッチング制御する必要はなく、表示画面全体として、表示情報に秘匿性を持たせたい場合に一括して電圧が印加できればよい。そこで、図５に示すように、それぞれの視野角制御画素２０は、スイッチング素子であるＴＦＴを解することなく、信号線と直接接続することができる。   FIG. 4 is a plan view of the vicinity of the viewing angle control pixel of the liquid crystal display device according to Embodiment 1 of the present invention. The voltage application to the viewing angle control pixel 20 can be performed via a switching element. FIG. 5 is another plan view of the vicinity of the viewing angle control pixel of the liquid crystal display device according to Embodiment 1 of the present invention. The viewing angle control pixel 20 in the present invention does not need to be subjected to switching control for each pixel, and it is sufficient that a voltage can be applied collectively when it is desired to conceal display information as a whole display screen. Therefore, as shown in FIG. 5, each viewing angle control pixel 20 can be directly connected to the signal line without solving the TFT as a switching element.

図６は、本発明の実施の形態１におけるＲＧＢ各画素における交流の印加電圧信号とコモン電圧Ｖｃｏｍとの関係を示した図であり、信号振幅に応じて視野角制御画素に電圧を印加することとなる。ＲＧＢ各画素における電圧信号は、画素に印加された後にスイッチング素子であるＴＦＴの突き抜けにより電圧が下がる。従って、図６に示すように、コモン電圧Ｖｃｏｍは、印加電圧信号の信号センタ値よりも低い値となる。   FIG. 6 is a diagram showing the relationship between the AC applied voltage signal and the common voltage Vcom in each of the RGB pixels according to the first embodiment of the present invention, in which a voltage is applied to the viewing angle control pixel according to the signal amplitude. It becomes. The voltage signal in each of the RGB pixels drops after being applied to the pixel due to the penetration of the TFT as a switching element. Therefore, as shown in FIG. 6, the common voltage Vcom is lower than the signal center value of the applied voltage signal.

ここで、本発明においては、先の図５で示したように、視野角制御画素２０にはスイッチング素子であるＴＦＴを設ける必要がない。従って、視野角制御画素２０においては、ＲＧＢ画素において生じていたようなＴＦＴの突き抜け電圧がない。その結果、視野角制御画素２０とＲＧＢ画素とでは、最適なコモン電圧が異なることとなる。   Here, in the present invention, as shown in FIG. 5, the viewing angle control pixel 20 does not need to be provided with a TFT as a switching element. Therefore, in the viewing angle control pixel 20, there is no TFT punch-through voltage that occurs in the RGB pixel. As a result, the optimum common voltage is different between the viewing angle control pixel 20 and the RGB pixel.

しかしながら、ＲＧＢ画素のコモン電圧と、視野角制御画素のコモン電圧とが異なる場合には、むら等の不良が起こることとなる。そこで、本発明の液晶表示装置は、視野角制御画素２０の信号センタ値を、ＲＧＢ画素のコモン電圧と等しくするように調整する視野角制御電圧調整部を備えている。   However, when the common voltage of the RGB pixels and the common voltage of the viewing angle control pixel are different, defects such as unevenness occur. Therefore, the liquid crystal display device of the present invention includes a viewing angle control voltage adjusting unit that adjusts the signal center value of the viewing angle control pixel 20 to be equal to the common voltage of the RGB pixels.

すなわち、視野角制御電圧調整部は、ＲＧＢ各画素のコモン電圧を読み取り、視野角制御画素２０に印加する電圧信号の信号センタ値が、このコモン電圧と等しくなるように調整しながら、印加電圧信号を出力する。これにより、むら等の不良を抑えた液晶表示装置を実現できる。   That is, the viewing angle control voltage adjustment unit reads the common voltage of each RGB pixel and adjusts the applied voltage signal while adjusting the signal center value of the voltage signal applied to the viewing angle control pixel 20 to be equal to the common voltage. Is output. As a result, a liquid crystal display device in which defects such as unevenness are suppressed can be realized.

図７は、本発明の実施の形態１におけるＤＯＴ反転の信号線の波形を示した図である。図７（ａ）は、ＲＧＢ画素からなる従来の信号線の波形を示している。これに対して、図７（ｂ）は、視野角制御画素２０をさらに備えた本発明の信号線の波形を示している。図７に示すように、視野角制御画素２０が追加された場合には、ＲＧＢの３画素＋視野角制御画素の４画素が１組となってその繰り返しの配列となる。   FIG. 7 is a diagram showing a waveform of a signal line for DOT inversion in Embodiment 1 of the present invention. FIG. 7A shows the waveform of a conventional signal line composed of RGB pixels. On the other hand, FIG. 7B shows the waveform of the signal line of the present invention further including the viewing angle control pixel 20. As shown in FIG. 7, when viewing angle control pixels 20 are added, four pixels of 3 pixels of RGB + viewing angle control pixels form a set and repeat the arrangement.

従って、視野角制御画素の交流の印加電圧波形は、４画素おきの信号となるため、すべてが同相の信号となる。そこで、視野角制御電圧調整部は、ＲＧＢ画素の制御信号と同期し、かつ、すべての視野角制御画素に同一の電圧信号を出力することができ、構成を簡略化できる。   Accordingly, since the AC applied voltage waveform of the viewing angle control pixel is a signal every four pixels, all are in-phase signals. Therefore, the viewing angle control voltage adjusting unit can synchronize with the RGB pixel control signals and output the same voltage signal to all viewing angle control pixels, thereby simplifying the configuration.

以上のように、実施の形態１によれば、ＲＧＢ画素とは独立し、個別にスイッチング制御する必要のない視野角制御画素を備えることにより、視野角調整を行える液晶表示装置を容易に実現できる。さらに、ＲＢＧ画素のコモン電圧と等しい信号センタ値を有する電圧信号を視野角制御画素に印加することができ、むら等の不良を抑制した液晶表示装置を実現できる。さらに、視野角制御画素に印加する電圧信号として、同相の共通化した信号を用いることができ、構成を簡略化できる。   As described above, according to the first embodiment, it is possible to easily realize a liquid crystal display device capable of adjusting the viewing angle by including the viewing angle control pixels that are independent of the RGB pixels and do not need to be individually switched. . Furthermore, a voltage signal having a signal center value equal to the common voltage of the RBG pixel can be applied to the viewing angle control pixel, and a liquid crystal display device in which defects such as unevenness are suppressed can be realized. Furthermore, a common signal having the same phase can be used as the voltage signal applied to the viewing angle control pixel, and the configuration can be simplified.

本発明の実施の形態１における液晶表示装置のＲＧＢ各画素および視野角制御画素の平面図である。It is a top view of each RGB pixel and viewing angle control pixel of the liquid crystal display device in Embodiment 1 of this invention. 本発明の実施の形態１における左右方位のコモン電極を有する視野角制御画素での液晶分子の動作の説明図である。It is explanatory drawing of operation | movement of the liquid crystal molecule | numerator in the viewing angle control pixel which has a common electrode of the left-right direction in Embodiment 1 of this invention. 本発明の実施の形態１における視野角制御画素の電圧印加による視野角依存の輝度分布を示す図である。It is a figure which shows the viewing angle dependent luminance distribution by the voltage application of the viewing angle control pixel in Embodiment 1 of this invention. 本発明の実施の形態１における液晶表示装置の視野角制御画素近傍の平面図である。FIG. 3 is a plan view of the vicinity of a viewing angle control pixel of the liquid crystal display device according to Embodiment 1 of the present invention. 本発明の実施の形態１における液晶表示装置の視野角制御画素近傍の別の平面図である。It is another top view of the viewing angle control pixel vicinity of the liquid crystal display device in Embodiment 1 of this invention. 本発明の実施の形態１におけるＲＧＢ各画素における交流の印加電圧信号とコモン電圧Ｖｃｏｍとの関係を示した図である。It is the figure which showed the relationship between the alternating applied voltage signal and common voltage Vcom in each RGB pixel in Embodiment 1 of this invention. 本発明の実施の形態１におけるＤＯＴ反転の信号線の波形を示した図である。It is the figure which showed the waveform of the signal line | wire of DOT inversion in Embodiment 1 of this invention. 秘匿モードを有する従来の液晶表示装置の説明図である。It is explanatory drawing of the conventional liquid crystal display device which has a secrecy mode. 従来のＦＦＳ方式の液晶表示装置のＲＧＢ各画素の平面図である。It is a top view of each RGB pixel of the liquid crystal display device of the conventional FFS system. 従来のＦＦＳ方式の液晶表示装置の電圧印加による液晶分子の動作の説明図である。It is explanatory drawing of operation | movement of the liquid crystal molecule by the voltage application of the conventional FFS system liquid crystal display device.

符号の説明Explanation of symbols

１１、１１ａ、１１ｂ コモン電極、２０ 視野角制御画素、２１ａ、２１ｂ コモン電極。
11, 11a, 11b Common electrode, 20 Viewing angle control pixel, 21a, 21b Common electrode.

Claims (3)

ＦＦＳ方式により液晶分子が傾くように配向制御されたＲＧＢの各画素の集合からなる表示画面を有する液晶表示装置であって、
上下方位あるいは左右方位に液晶分子が傾くように配向制御され、画素ごとにスイッチングすることなしに前記表示画面内で一括の電圧信号が印加される視野角制御画素をさらに備えることを特徴とする液晶表示装置。 A liquid crystal display device having a display screen composed of a set of RGB pixels whose orientation is controlled so that liquid crystal molecules are tilted by the FFS method,
A liquid crystal further comprising a viewing angle control pixel that is controlled so that liquid crystal molecules are tilted in the vertical direction or the horizontal direction, and a collective voltage signal is applied in the display screen without switching for each pixel. Display device. 請求項１に記載の液晶表示装置において、
前記視野角制御画素に印加される前記電圧信号の信号センタ値が、前記ＲＧＢの各画素のコモン電圧と等しくなるように調整する視野角制御電圧調整部を備えることを特徴とする液晶表示装置。 The liquid crystal display device according to claim 1.
A liquid crystal display device comprising: a viewing angle control voltage adjusting unit that adjusts a signal center value of the voltage signal applied to the viewing angle control pixel to be equal to a common voltage of each of the RGB pixels. 請求項２に記載の液晶表示装置において、
前記視野角制御電圧調整部は、ＲＧＢ画素の制御信号と同期し、かつ、すべての視野角制御画素に同一の信号を出力することを特徴とする液晶表示装置。
The liquid crystal display device according to claim 2,
The liquid crystal display device, wherein the viewing angle control voltage adjustment unit outputs the same signal to all the viewing angle control pixels in synchronization with the RGB pixel control signals.
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