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JP2622190B2 - Liquid crystal display - Google Patents

Liquid crystal display

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Publication number
JP2622190B2
JP2622190B2 JP2326424A JP32642490A JP2622190B2 JP 2622190 B2 JP2622190 B2 JP 2622190B2 JP 2326424 A JP2326424 A JP 2326424A JP 32642490 A JP32642490 A JP 32642490A JP 2622190 B2 JP2622190 B2 JP 2622190B2
Authority
JP
Japan
Prior art keywords
voltage
liquid crystal
counter electrode
crystal display
line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP2326424A
Other languages
Japanese (ja)
Other versions
JPH04191821A (en
Inventor
忠継 西谷
高明 家本
宏文 福岡
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sharp Corp
Original Assignee
Sharp Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sharp Corp filed Critical Sharp Corp
Priority to JP2326424A priority Critical patent/JP2622190B2/en
Publication of JPH04191821A publication Critical patent/JPH04191821A/en
Application granted granted Critical
Publication of JP2622190B2 publication Critical patent/JP2622190B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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  • Liquid Crystal (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Testing Electric Properties And Detecting Electric Faults (AREA)

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明は液晶表示装置に関し、特に液晶パネルの共通
電極(対向電極)に電圧を印加する回路が改良された液
晶表示装置に関する。
Description: BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having an improved circuit for applying a voltage to a common electrode (counter electrode) of a liquid crystal panel.

(従来の技術) 例えば、TFT(Thin Film Transistor)型ドットマト
リクス液晶表示装置では、液晶層を挟んで一方に並行に
走る複数の走査電極とそれらに交差する信号電極が、他
方に1枚の共通電極が設けられている。画像を表示する
場合には、1本の走査電極に走査信号を出力することに
よりその走査線上の各絵素のTFTを導通とし、信号電極
に画像信号を出力して、液晶層を挟んで対向する共通電
極(以下、対向電極という)との間でその絵素の液晶層
に信号電圧を印加する。
(Prior Art) For example, in a TFT (Thin Film Transistor) type dot matrix liquid crystal display device, a plurality of scanning electrodes running in parallel to one side across a liquid crystal layer and a signal electrode intersecting them are provided with one common electrode on the other side. Electrodes are provided. When displaying an image, a scanning signal is output to one scanning electrode to make the TFT of each pixel on the scanning line conductive, an image signal is output to the signal electrode, and the liquid crystal layer is interposed therebetween. A signal voltage is applied to the liquid crystal layer of the pixel between the common electrode (hereinafter, referred to as a counter electrode).

(発明が解決しようとする課題) 対向電極に対しては駆動回路に含まれる電圧印加回路
から電圧が印加され、信号電圧のレベルに影響されて対
向電極全体の電圧が変動した場合には、駆動回路がこの
変動を検出し、その変動を補償するように動作する。し
かし、駆動回路は液晶パネルとは別に設けられているた
め、対向電極の内部で微小な電圧変動が生じた場合、こ
の変動は駆動回路までは伝達されず、電圧印加回路によ
る補償がうまく行われない。
(Problems to be Solved by the Invention) When a voltage is applied to the common electrode from a voltage application circuit included in the drive circuit and the voltage of the entire common electrode fluctuates due to the level of the signal voltage, the driving is performed. A circuit detects this variation and operates to compensate for the variation. However, since the drive circuit is provided separately from the liquid crystal panel, if a small voltage fluctuation occurs inside the counter electrode, this fluctuation is not transmitted to the drive circuit, and compensation by the voltage application circuit is performed well. Absent.

例えば、第2図に示すように、液晶パネル20の中央部
22のみを黒とし、その周囲24を全て白とするような画像
信号を入力しても、実際には黒色部22の両側の領域25、
26の色調、輝度は黒色部22の影響を受け、その両側の領
域25、26は僅かに黒く表示される。これはシャドーイン
グと呼ばれ、走査電極に対向する部分の対向電極の中央
部22とその両側の領域25、26とで電位が僅かに異なるた
めに生じる現象である。このため、従来の液晶表示装置
では画質が劣るという欠点がある。
For example, as shown in FIG.
Even if an image signal is input such that only 22 is black and the surrounding area 24 is all white, actually, the regions 25 on both sides of the black portion 22,
The color tone and the brightness of the pixel 26 are affected by the black portion 22, and the regions 25 and 26 on both sides thereof are displayed slightly black. This is called shadowing, and is a phenomenon that occurs because the potential is slightly different between the central portion 22 of the counter electrode facing the scanning electrode and the regions 25 and 26 on both sides thereof. For this reason, the conventional liquid crystal display device has a disadvantage that the image quality is inferior.

本発明はこのような現状に鑑みてなされたものであ
り、その目的とするところは、上記欠点を解消し、シャ
ドーイングを防止し、画質を向上させることのできる液
晶表示装置を提供することにある。
The present invention has been made in view of such a situation, and an object of the present invention is to provide a liquid crystal display device which can solve the above-described drawbacks, prevent shadowing, and improve image quality. is there.

(課題を解決するための手段) 本発明の液晶表示装置は、液晶パネルの一方の面に複
数の信号電極と複数の走査電極が交差して配設され、他
方の面に該面を覆う対向電極が設けられた液晶表示装置
であって、対向電極の所定位置に所定の電圧を印加する
手段、対向電極の該所定位置とは異なる該対向電極の他
の位置の電圧を検出する手段、及び該検出した電圧値に
応じて上記印加電圧を調整する手段を備えており、その
ことにより上記目的が達成される。
(Means for Solving the Problems) In a liquid crystal display device according to the present invention, a plurality of signal electrodes and a plurality of scanning electrodes are arranged on one surface of a liquid crystal panel so as to intersect, and the other surface covers the surface. A liquid crystal display device provided with electrodes, a unit for applying a predetermined voltage to a predetermined position of the counter electrode, a unit for detecting a voltage of another position of the counter electrode different from the predetermined position of the counter electrode, and A means for adjusting the applied voltage according to the detected voltage value is provided, thereby achieving the above object.

(実施例) 本発明を実施例について以下に説明する。(Examples) The present invention will be described below with reference to examples.

第1図に、本発明の一実施例であるマトリクス型液晶
表示装置の液晶パネルの一方の面に配置される対向電極
10、及びその対向電極10に電圧を印加する回路12を示
す。図示しないが、液晶パネルの他方の面には複数本の
並行する走査電極及びそれらに交差する複数本の信号電
極が配置されている。
FIG. 1 shows a counter electrode disposed on one surface of a liquid crystal panel of a matrix type liquid crystal display device according to an embodiment of the present invention.
10 shows a circuit 12 for applying a voltage to a counter electrode 10 thereof. Although not shown, a plurality of parallel scanning electrodes and a plurality of signal electrodes intersecting with them are arranged on the other surface of the liquid crystal panel.

電圧印加回路12は入力信号SgをオペアンプOP1で増幅
し、電圧印加線L1を通して対向電極10に印加する。ここ
で、電圧印加線L1は対向電極10の長辺の一方(図では上
方)の中央に接続されているが、その長辺に対向する長
辺(図では下方)の中央には電圧帰還線L2が接続され、
その位置における対向電極10の電圧を電圧印加回路12に
帰還させている。電圧帰還線L2はオペアンプOP1の信号
入力線に抵抗R1を介して接続されており、この抵抗R1の
値と信号Sgの入力部に挿入された抵抗R2sの値により、
入力信号Sgの増幅率が決定される。また、オペアンプOP
1の接地入力に接続される抵抗R3は対向電極10のオフセ
ット電圧を定めるためのものである。
The voltage application circuit 12 amplifies the input signal Sg with the operational amplifier OP1 and applies the amplified signal to the counter electrode 10 through the voltage application line L1. Here, the voltage application line L1 is connected to the center of one of the long sides of the counter electrode 10 (upper in the figure), and the center of the longer side (lower in the figure) opposite to the long side is a voltage feedback line. L2 is connected,
The voltage of the counter electrode 10 at that position is fed back to the voltage application circuit 12. The voltage feedback line L2 is connected to the signal input line of the operational amplifier OP1 via the resistor R1, and according to the value of the resistor R1 and the value of the resistor R2s inserted in the input portion of the signal Sg,
The amplification factor of the input signal Sg is determined. Also, the operational amplifier OP
The resistor R3 connected to one ground input is for determining the offset voltage of the counter electrode 10.

本実施例ではさらに、電圧印加線L1と電圧帰還線L2と
を並列のコンデンサCFと抵抗RFとで接続している。この
抵抗RFは可変抵抗となっており、その値を変化させるこ
とにより、電圧帰還線L2から電圧印加回路12への帰還量
を変化させることができる。
In this embodiment, the voltage application line L1 and the voltage feedback line L2 are further connected by a parallel capacitor CF and a resistor RF. This resistor RF is a variable resistor, and by changing its value, the amount of feedback from the voltage feedback line L2 to the voltage application circuit 12 can be changed.

本実施例の対向電極10及び電圧印加回路12はこのよう
な構成となっているため、液晶パネルを挟んで対向電極
10に対向する信号電極に印加される信号電圧の分布に影
響されて、対向電極10の内部で電圧の不均一性が生じて
も、電圧帰還線L2がその変動を電圧印加回路12に帰還
し、印加電圧を一定にするような方向にオペアンプOP1
の増幅度を変化させる。これにより、1本の走査線上に
おいて、ある部分の絵素の色調、輝度が他の部分の絵素
の色調等に影響されることにより生じるシャドーイング
現象が防止でき、液晶パネル全面でムラのない表示を行
うことができる。なお、電圧帰還線L2からの電圧帰還量
が大き過ぎると通常の表示部の色調、輝度等にも影響を
及ぼし、正常な表示が行えなくなる場合がある。そのた
め、電圧帰還線L2と電圧印加線L1の間を接続する可変抵
抗RFの値を調整することにより帰還量を増減させて、シ
ャドーイングを防止しつつ最適の表示を得るように調整
することができるようになっている。
Since the counter electrode 10 and the voltage applying circuit 12 of the present embodiment have such a configuration, the counter electrode 10 and the voltage
Even if the voltage non-uniformity occurs inside the counter electrode 10 due to the distribution of the signal voltage applied to the signal electrode facing the counter electrode 10, the voltage feedback line L2 returns the fluctuation to the voltage applying circuit 12. , The operational amplifier OP1 in the direction to keep the applied voltage constant.
To change the amplification degree. This can prevent a shadowing phenomenon caused by the influence of the color tone and luminance of a picture element in a certain part on the one scanning line due to the color tone of the picture element in another part, and there is no unevenness over the entire liquid crystal panel. Display can be performed. Note that if the amount of voltage feedback from the voltage feedback line L2 is too large, it also affects the color tone, luminance, and the like of a normal display unit, and normal display may not be performed. Therefore, by adjusting the value of the variable resistor RF connecting between the voltage feedback line L2 and the voltage application line L1, the amount of feedback can be increased or decreased to adjust to obtain an optimal display while preventing shadowing. I can do it.

第1図の実施例では電圧印加線L1と電圧帰還線L2は対
向電極10の長辺の中央に接続されていたが、両電圧線L
1、L2はその他にも種々の形態で対向電極に接続するこ
とができる。第3図(a)は第1図の実施例の接続例を
単純化して示したものであるが、その他に例えば同図
(b)〜(g)のような接続を行うことができる。
In the embodiment of FIG. 1, the voltage application line L1 and the voltage feedback line L2 are connected to the center of the long side of the counter electrode 10,
1, L2 can be connected to the counter electrode in various other forms. FIG. 3 (a) shows a simplified connection example of the embodiment of FIG. 1, but other connections such as those shown in FIGS. 3 (b) to (g) can be made.

第3図(b)、(c)はいずれも、電圧印加線L1と電
圧帰還線L2を1本ずつ用いる例であるが、同図(d)〜
(g)は複数の電圧印加線L1と電圧帰還線L2を用いる例
を示している。また、同図(f)と(g)では液晶パネ
ルの4辺の全てに複数の線を接続しているため、対向電
極の電圧分布の不均一性を最も良好に補正することがで
きる。
3 (b) and 3 (c) are examples in which one voltage application line L1 and one voltage feedback line L2 are used, respectively.
(G) shows an example in which a plurality of voltage application lines L1 and voltage feedback lines L2 are used. Further, in FIGS. 7F and 7G, since a plurality of lines are connected to all four sides of the liquid crystal panel, the non-uniformity of the voltage distribution of the counter electrode can be corrected most satisfactorily.

(発明の効果) 本発明では、同一走査線上での絵素電圧の負荷変動に
よって生じる対向電極内部の微弱な電圧変動を検出し、
その変動に基づいて対向電極に印加する電圧値を制御す
る。これにより、シャドーイング現象を防止し、液晶パ
ネル全面で色調、輝度等にムラのない表示を行うことが
できる。
(Effect of the Invention) In the present invention, a weak voltage fluctuation inside the counter electrode caused by a load fluctuation of the pixel voltage on the same scanning line is detected,
The voltage value applied to the counter electrode is controlled based on the fluctuation. Accordingly, the shadowing phenomenon can be prevented, and a display without unevenness in color tone, luminance, and the like can be performed on the entire liquid crystal panel.

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

第1図は本発明の一実施例である液晶表示装置の対向電
極及びその電圧印加回路の回路図、第2図は液晶表示装
置におけるシャドーイング現象を説明する説明図、第3
図(a)〜(g)は対向電極に電圧印加線と電圧帰還線
を接続する場合の種々の形態例を示す接続図である。 10……対向電極、12……電圧印加回路、L1……電圧印加
線、L2……電圧帰還線、CF……帰還コンデンサ、RF……
帰還量調整可変抵抗、20……液晶パネル、22……黒色表
示部、25、26……シャドーイング発生部
FIG. 1 is a circuit diagram of a counter electrode of a liquid crystal display device according to one embodiment of the present invention and a voltage application circuit thereof, FIG. 2 is an explanatory diagram for explaining a shadowing phenomenon in the liquid crystal display device,
FIGS. 7A to 7G are connection diagrams showing various embodiments in the case where a voltage application line and a voltage feedback line are connected to a counter electrode. 10 counter electrode, 12 voltage applying circuit, L1 voltage applying line, L2 voltage feedback line, CF feedback capacitor, RF
Feedback amount adjustment variable resistor, 20: LCD panel, 22: Black display unit, 25, 26: Shadowing generation unit

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭64−29899(JP,A) 特開 昭63−246782(JP,A) 特開 昭63−246783(JP,A) ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-29899 (JP, A) JP-A-63-246782 (JP, A) JP-A-63-246783 (JP, A)

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】液晶パネルの一方の面に複数の信号電極と
複数の走査電極が交差して配設され、他方の面に該面を
覆う対向電極が設けられた液晶表示装置であって、 対向電極の所定位置に所定の電圧を印加する手段、 対向電極の該所定位置とは異なる該対向電極の他の位置
の電圧を検出する手段、及び 該検出した電圧値に応じて上記印加電圧を調整する手段 を備えている液晶表示装置。
1. A liquid crystal display device comprising: a plurality of signal electrodes and a plurality of scanning electrodes arranged on one surface of a liquid crystal panel so as to cross each other; and a counter electrode covering the other surface provided on the other surface. Means for applying a predetermined voltage to a predetermined position of the counter electrode, means for detecting a voltage at another position of the counter electrode different from the predetermined position of the counter electrode, and the applied voltage according to the detected voltage value A liquid crystal display device comprising means for adjusting.
JP2326424A 1990-11-27 1990-11-27 Liquid crystal display Expired - Lifetime JP2622190B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2326424A JP2622190B2 (en) 1990-11-27 1990-11-27 Liquid crystal display

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2326424A JP2622190B2 (en) 1990-11-27 1990-11-27 Liquid crystal display

Publications (2)

Publication Number Publication Date
JPH04191821A JPH04191821A (en) 1992-07-10
JP2622190B2 true JP2622190B2 (en) 1997-06-18

Family

ID=18187642

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2326424A Expired - Lifetime JP2622190B2 (en) 1990-11-27 1990-11-27 Liquid crystal display

Country Status (1)

Country Link
JP (1) JP2622190B2 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2872511B2 (en) * 1992-12-28 1999-03-17 シャープ株式会社 Display device common electrode drive circuit
JPH09218388A (en) * 1996-02-09 1997-08-19 Hosiden Corp Liquid crystal display device
JP3527168B2 (en) 1999-06-02 2004-05-17 シャープ株式会社 Liquid crystal display
JP2001108966A (en) 1999-10-13 2001-04-20 Sharp Corp Method for driving liquid crystal panel and driving device
JP5026738B2 (en) * 2006-05-31 2012-09-19 株式会社ジャパンディスプレイイースト Display device
KR101400384B1 (en) * 2007-11-21 2014-05-26 엘지디스플레이 주식회사 Liquid crystal display device
JP2012078415A (en) * 2010-09-30 2012-04-19 Hitachi Displays Ltd Display device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2506796B2 (en) * 1987-07-24 1996-06-12 松下電器産業株式会社 Liquid crystal display

Also Published As

Publication number Publication date
JPH04191821A (en) 1992-07-10

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