JPH09230306A - Liquid crystal display device - Google Patents

Liquid crystal display device

Info

Publication number
JPH09230306A
JPH09230306A JP4132396A JP4132396A JPH09230306A JP H09230306 A JPH09230306 A JP H09230306A JP 4132396 A JP4132396 A JP 4132396A JP 4132396 A JP4132396 A JP 4132396A JP H09230306 A JPH09230306 A JP H09230306A
Authority
JP
Japan
Prior art keywords
voltage
signal
circuit
liquid crystal
scanning
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.)
Pending
Application number
JP4132396A
Other languages
Japanese (ja)
Inventor
Akinori Matsushita
明紀 松下
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.)
Tokyo Sanyo Electric Co Ltd
Sanyo Electric Co Ltd
Original Assignee
Tokyo Sanyo Electric Co Ltd
Tottori Sanyo Electric Co Ltd
Sanyo Electric Co Ltd
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 Tokyo Sanyo Electric Co Ltd, Tottori Sanyo Electric Co Ltd, Sanyo Electric Co Ltd filed Critical Tokyo Sanyo Electric Co Ltd
Priority to JP4132396A priority Critical patent/JPH09230306A/en
Publication of JPH09230306A publication Critical patent/JPH09230306A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To easily adjust display density and temp. compensation in the so- called simple matrix liquid crystal display device. SOLUTION: Any one of positive/negative selection voltages is selected and used as a scan voltage, and a signal voltage in the vicinity of an intermediate value between the positive selection voltage and the negative selection voltage is used selectively as the signal voltage according to an image signal, and at this time, a signal circuit 33 supplies the signal voltage depending on a peripheral temp. Further, a power source circuit 44 supplying the voltage of a prescribed bias value to a scan circuit 22 and the signal circuit 33 is constituted so that the voltage of the bias value is obtained by resistance division as the selection voltage, and a temp. dependent resistance element is used as the resistance for obtaining the signal voltage among the resistance division. Thus, the density is temp. compensated by voltage adjustment and bias ratio adjustment.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明はいわゆる単純マトリ
クス駆動に好適な液晶表示装置に関する。
The present invention relates to a liquid crystal display device suitable for so-called simple matrix driving.

【0002】[0002]

【従来の技術】従来より、互いに直交する電極群を有す
る液晶セルの駆動、いわゆる単純マトリクス駆動に於て
は、一方の電極群の電極に順次電圧レベルの高い電圧を
与え、その電圧レベルの高い電圧を印加しているときに
他方の電極群に画信号に応じた電圧を与える線順次走査
を電圧平均化法に従ったバイアス電圧で行っており、さ
らに液晶に直流を印加しないために特公昭57−577
18号公報に示されるように極性反転をさせていた。
2. Description of the Related Art Conventionally, in driving a liquid crystal cell having mutually orthogonal electrode groups, that is, so-called simple matrix driving, a voltage of a high voltage level is sequentially applied to the electrodes of one of the electrode groups to increase the voltage level. Line-sequential scanning that applies a voltage according to the image signal to the other electrode group while applying a voltage is performed with a bias voltage according to the voltage averaging method. 57-577
The polarity was reversed as shown in Japanese Patent No. 18.

【0003】このような駆動において、液晶層には、走
査時には所定の電圧値の電圧が、また非走査時にも信号
電圧による一定の電圧がそれぞれ印加され、それが交流
化されるものの、選択画素においては所定の実効値の電
圧が印加され、非選択画素においても幾らかの実効値の
電圧が印加されることとなった。
In such driving, a voltage having a predetermined voltage value is applied to the liquid crystal layer during scanning, and a constant voltage based on a signal voltage is applied even during non-scanning, which is converted into an alternating current. In, the voltage of a predetermined effective value was applied, and some effective value voltage was applied to the non-selected pixels.

【0004】[0004]

【発明が解決しようとする課題】ところがこのように非
選択画素にも電圧が印加されることによって、選択時の
実効値と非選択時の実効値の間で表示濃度(光透過率)
が大きく変化する必要があり、一方液晶セルは周知の如
く駆動電圧や周囲温度によってこの濃度の変化点が変化
するので、これらを使用環境によって調整する必要があ
った。そしてこのような調整は一般的には、液晶セルの
電源回路に供給する電圧を使用者が可変抵抗等を用いて
見易い画面になる様に調整していたが、煩雑であった。
そこで走査回路や信号回路等に所定のバイアス値の電圧
を供給する電源回路を抵抗分割によって構成し、その抵
抗分割回路にサーミスターやポジスタを組合せて周囲温
度に対する電圧補償を行うことが提案されたものの、温
度依存抵抗素子の温度特性が所望の調整に対して逆向き
であったり、温度依存抵抗素子の温度に対する変化率が
液晶セルの温度特性の変化率と一致しないため、実用的
でなかった。
However, since the voltage is applied to the non-selected pixels in this way, the display density (light transmittance) between the effective value at the time of selection and the effective value at the time of non-selection is increased.
Of the liquid crystal cell, on the other hand, the change point of the density of the liquid crystal cell changes depending on the driving voltage and the ambient temperature, as is well known. In general, such adjustment is performed by adjusting the voltage supplied to the power supply circuit of the liquid crystal cell so that the user can easily see the screen by using a variable resistor or the like, but it is complicated.
Therefore, it has been proposed that a power supply circuit that supplies a voltage of a predetermined bias value to a scanning circuit or a signal circuit is configured by resistance division, and that the resistance division circuit is combined with a thermistor or posistor to perform voltage compensation with respect to ambient temperature. However, it was not practical because the temperature characteristic of the temperature-dependent resistance element was opposite to the desired adjustment, or the rate of change of the temperature-dependent resistance element with respect to temperature did not match the rate of change of the temperature characteristic of the liquid crystal cell. .

【0005】一方単純マトリクスの表示装置は、交流化
信号の切替え時に液晶に起因する大きな容量性負荷電流
が流れ、消費電力が多くなり、また大表示容量化に伴っ
て高速高耐圧集積回路が必要になってきた。しかし集積
回路にとって、高速化と高耐圧化は相反する仕様であ
り、実現が困難となっていた。そこで走査信号を大きい
正負の電圧とし、信号電圧を正の選択電圧と負の選択電
圧の中間値近傍の電圧とすることを検討し一定の効果を
得たが、上述した温度による動作点の変動に対しては従
来の液晶セルの電源回路に供給する電圧を使用者が可変
抵抗等を用いて見易い画面になる様に調整する方法を用
いるに過ぎなかった。
On the other hand, in a simple matrix display device, a large capacitive load current caused by the liquid crystal flows at the time of switching the alternating signal, power consumption increases, and a high-speed and high-voltage integrated circuit is required as the display capacity increases. Has become. However, for an integrated circuit, high speed and high withstand voltage are conflicting specifications, making it difficult to realize. Therefore, we considered the scanning signal to be a large positive and negative voltage, and set the signal voltage to a voltage near the intermediate value between the positive selection voltage and the negative selection voltage and obtained a certain effect. For this, only the conventional method of adjusting the voltage supplied to the power supply circuit of the liquid crystal cell so that the user can easily see the screen by using a variable resistor or the like has been used.

【0006】[0006]

【課題を解決するための手段】本発明は、上述した液晶
セルの濃度の変化点が、印加電圧の大きさや温度のみで
なくバイアス比にも依存することを考慮して成されたも
のである。
SUMMARY OF THE INVENTION The present invention has been made in consideration of the fact that the above-mentioned change point of the concentration of the liquid crystal cell depends not only on the magnitude and temperature of the applied voltage but also on the bias ratio. .

【0007】即ち本発明は、いわゆる単純マトリクスの
液晶セルの駆動において、走査電圧に正負の選択電圧の
いずれかを選択し用い、信号電圧に正の選択電圧と負の
選択電圧の中間値近傍の信号電圧を画信号に応じて選択
的に用い、この時信号回路が周囲温度に依存させて信号
電圧を供給するように構成したものであり、あるいはま
た、走査回路と信号回路に所定のバイアス値の電圧を供
給する電源回路を選択電圧を抵抗分割によってバイアス
値の電圧を得るように構成し、その抵抗分割のうち信号
電圧を得るための抵抗として、温度の上昇に伴ってバイ
アス比が小さくなるように接続された温度依存抵抗素子
を用いるものである。
That is, according to the present invention, in driving a so-called simple matrix liquid crystal cell, either a positive or negative selection voltage is selected and used as a scanning voltage, and a signal voltage in the vicinity of an intermediate value between a positive selection voltage and a negative selection voltage is used. The signal voltage is selectively used according to the image signal, and at this time, the signal circuit is configured to supply the signal voltage depending on the ambient temperature, or a predetermined bias value is applied to the scanning circuit and the signal circuit. The power supply circuit that supplies the voltage is configured to obtain the voltage of the bias value by resistance division of the selection voltage, and as the resistance for obtaining the signal voltage of the resistance division, the bias ratio becomes smaller as the temperature rises. The temperature-dependent resistance element connected in this way is used.

【0008】[0008]

【発明の実施の形態】まず本発明の原理について、例え
ば、フレーム毎に極性反転する交流化信号Mを与えるこ
とで交流駆動する場合、最初のフレームの走査の時間に
走査電極にV0を与え、他方の信号電極には表示したい
とき(選択画素)はV1を与え、そして次のフレームに
おいて、走査電極にV1を与え、信号電極にはV0を与
えるような従来の駆動方式を例に、説明する。
BEST MODE FOR CARRYING OUT THE INVENTION First, regarding the principle of the present invention, for example, when AC driving is performed by applying an alternating signal M whose polarity is inverted for each frame, V0 is applied to the scanning electrode at the time of scanning of the first frame, An example of a conventional driving method in which V1 is applied to the other signal electrode to display (selected pixel), V1 is applied to the scanning electrode and V0 is applied to the signal electrode in the next frame will be described as an example. .

【0009】図1において、1は、いわゆる単純マトリ
クス駆動に用いる、互いに直交する電極群を有する液晶
セルで、2は、液晶セル1の一方の電極群の所定の電極
に選択電圧を走査電圧として与える走査回路である。3
は、液晶セル1の他方の電極群に信号電圧を画信号に応
じて与える信号回路で、4は、走査回路2と信号回路3
に所定のバイアス値の電圧と各回路の駆動電圧を供給す
る電源回路である。電源回路4は例えばパーソナルコン
ピュータなど表示装置を組み込む装置から30ボルトの
電圧を受け取り、3端子電源回路46によるロジック電
圧5ボルトと、液晶セル駆動バイアス電圧、例えば電圧
平均化法に従った、走査・信号選択電圧Vと、走査非選
択電圧Vcと信号非選択電圧Vsを5つの抵抗R、R0
による抵抗分割回路で形成し、これをバッファ5を介し
て出力している。
In FIG. 1, reference numeral 1 is a liquid crystal cell having mutually orthogonal electrode groups used for so-called simple matrix driving, and 2 is a predetermined electrode of one electrode group of the liquid crystal cell 1 with a selection voltage as a scanning voltage. It is a scanning circuit to give. 3
Is a signal circuit for applying a signal voltage to the other electrode group of the liquid crystal cell 1 according to an image signal, and 4 is a scanning circuit 2 and a signal circuit 3.
Is a power supply circuit that supplies a voltage having a predetermined bias value and a drive voltage for each circuit. The power supply circuit 4 receives a voltage of 30 V from a device incorporating a display device such as a personal computer, and a logic voltage of 5 V by a three-terminal power supply circuit 46 and a liquid crystal cell drive bias voltage, for example, a scanning / scanning method according to a voltage averaging method. The signal selection voltage V, the scanning non-selection voltage Vc, and the signal non-selection voltage Vs are divided into five resistors R and R0.
It is formed by a resistance division circuit according to (4) and is output via the buffer 5.

【0010】これらの抵抗分割回路は、いわゆる適正バ
イアス比という理論があり、これは走査線数Nに対して
1/2+1で示されるバイアス比になる様に構成され、
例えばN=121のときR=1とR0=8との比率にな
るように抵抗値が選ばれるとき、もっともコントラスト
がよいとされている。従来はこのバイアス回路に供給さ
れる電源路、若しくは選択電圧間(V−V)にサーミス
タなどの温度依存抵抗素子を挿入するか、若しくは抵抗
分割回路のどれか(例えばR0)に替えてサーミスタを
挿入することで、上述した適正バイアス比を保ったまま
印加電圧を供給しようとしていたため、実際の周囲温度
に対して濃度の変化点の変化に対応した所定の電圧を供
給設定することが困難であった。
These resistance division circuits have a theory of what is called an appropriate bias ratio, which is configured to have a bias ratio represented by N 1/2 +1 with respect to the number N of scanning lines.
For example, when the resistance value is selected such that the ratio of R = 1 and R0 = 8 when N = 121, the contrast is said to be the best. Conventionally, a temperature-dependent resistance element such as a thermistor is inserted in the power supply path supplied to the bias circuit or between selected voltages (V-V), or the thermistor is replaced with one of the resistance division circuits (for example, R0). By inserting it, it was tried to supply the applied voltage while maintaining the above-mentioned proper bias ratio, so it is difficult to supply and set the predetermined voltage corresponding to the change of the change point of the concentration with respect to the actual ambient temperature. there were.

【0011】本発明は、このようないわゆる適性バイア
ス比が現実の液晶セルでは少しずれていることを考慮
し、むしろ同じ走査線数の液晶セルであっても異なるバ
イアス比の電圧を印加すると表示濃度やコントラストを
最良にする動作点(濃度の変化点に相当)の電圧が異な
ることを考慮してなされたものである。そして図1の例
では、バイアス比を定める抵抗のうち、非選択電圧を定
める抵抗Rの直列接続された2つずつに対して温度の上
昇に対して抵抗値が下がるサーミスタRtを各々並列接
続したものである。これによって温度の上昇に伴ってバ
イアス比が小さくなり、濃度の変化点の電圧が高く供給
され、見易い表示が提供できる。
The present invention considers that such a so-called proper bias ratio is slightly deviated in an actual liquid crystal cell, and even if liquid crystal cells having the same number of scanning lines are applied with different bias ratio voltages, the display is performed. This is done in consideration of the fact that the voltage at the operating point (corresponding to the changing point of the density) that maximizes the density and the contrast is different. In the example of FIG. 1, of the resistors that define the bias ratio, two thermistors R that define the non-selection voltage are connected in series, and the thermistors Rt whose resistance value decreases with increasing temperature are connected in parallel. It is a thing. As a result, the bias ratio becomes smaller as the temperature rises, the voltage at the concentration change point is supplied higher, and an easy-to-see display can be provided.

【0012】図2は本発明実施例の液晶表示装置のブロ
ック図で、11は互いに直交する電極群を有する液晶セ
ルで、例えばスーパーツイストネマティック液晶表示器
などの電界効果型液晶が利用できる。これらの液晶セル
11の電極は、いわゆる単純マトリクスを構成し、画素
交点に能動素子を持たないものである。
FIG. 2 is a block diagram of a liquid crystal display device according to an embodiment of the present invention. Reference numeral 11 is a liquid crystal cell having mutually orthogonal electrode groups, and for example, a field effect liquid crystal such as a super twist nematic liquid crystal display can be used. The electrodes of these liquid crystal cells 11 form a so-called simple matrix and do not have active elements at pixel intersections.

【0013】22は、その液晶セル11の一方の電極群
に走査電圧を与える走査回路で、正負の電圧−VL、+
VHと中間電圧Vmのいずれかを選択して所定の電極に
供給するものであり、このうち−VL、+VHは選択電
圧である。33は、液晶セル11の他方の電極群に画信
号に応じた信号電圧を与える信号回路で、特には走査回
路22の正の選択電圧+VHと負の選択電圧−VLの中
間値近傍の2種類の信号電圧−Vb、+Vbを画信号に
応じて選択的に電極に供給するものである。これらの電
圧関係は図3に示すとおりで、室温より若干低い温度で
適正バイアス比に近接したものとなる。図3aは交流化
信号Mと走査・駆動する電圧波形で、図3bは液晶に印
加される電圧であり、いずれも横軸は時間である。これ
らの図において走査電圧は一定の周期で正負いずれかの
選択電圧が選択される様子を示しており、信号電圧は画
信号と極性反転に伴って2つの値のうちどちらを選択さ
れるのか変化するので、2つの信号電圧のいずれをも算
盤の駒状に記載して表現している。
Reference numeral 22 is a scanning circuit for applying a scanning voltage to one electrode group of the liquid crystal cell 11, which is a positive or negative voltage -VL, +.
One of VH and the intermediate voltage Vm is selected and supplied to a predetermined electrode, of which -VL and + VH are selection voltages. Reference numeral 33 is a signal circuit for applying a signal voltage corresponding to an image signal to the other electrode group of the liquid crystal cell 11, and in particular, two types of voltage values in the vicinity of an intermediate value between the positive selection voltage + VH and the negative selection voltage -VL of the scanning circuit 22. The signal voltages -Vb and + Vb are selectively supplied to the electrodes according to the image signal. The relationship between these voltages is as shown in FIG. 3, which is close to the proper bias ratio at a temperature slightly lower than room temperature. FIG. 3a shows an alternating signal M and a voltage waveform for scanning / driving, and FIG. 3b shows a voltage applied to the liquid crystal, and in each case, the horizontal axis represents time. In these figures, the scanning voltage shows a state in which either a positive or negative selection voltage is selected at a constant cycle, and the signal voltage changes which of the two values is selected according to the image signal and the polarity inversion. Therefore, both of the two signal voltages are expressed by expressing them on the abacus piece.

【0014】44は、走査回路22と信号回路33に所
定のバイアス値の電圧を供給する電源回路で、少なくと
も正負の選択電圧−VL、+VHと信号電圧−Vb、+
Vbと中間電圧Vmとを出力し、より好ましくは、走査
回路22や信号回路33、さらには信号授受回路66や
バッファ45の駆動電圧Vic等をも供給する。この信
号授受回路66は、信号回路33に供給される各種タイ
ミング信号や画信号に応じた信号をバッファを介して伝
送するもので、走査回路22の駆動伝達レベルが供給電
源レベルと異なる場合レベルシフトを行ったり、初期化
信号を付加して与えるものである。
A power supply circuit 44 supplies a voltage having a predetermined bias value to the scanning circuit 22 and the signal circuit 33, and at least positive and negative selection voltages -VL, + VH and signal voltages -Vb, +.
It outputs Vb and the intermediate voltage Vm, and more preferably supplies the scanning circuit 22, the signal circuit 33, the signal transfer circuit 66, the drive voltage Vic of the buffer 45, and the like. The signal transmission / reception circuit 66 transmits signals corresponding to various timing signals and image signals supplied to the signal circuit 33 through a buffer. When the drive transmission level of the scanning circuit 22 is different from the power supply level, level shift is performed. Or by adding an initialization signal.

【0015】この電源回路44は、この表示装置が組み
込まれるパーソナルコンピュータなどから供給される電
源が、0−5ボルト電圧系である場合、そのまま走査回
路22と信号回路33の駆動電圧Viとして用てもよい
し、必要に応じて、電圧発生回路(DC/DCコンバー
タ)41により改めて0−5ボルト系の電圧を得てもよ
い。一方供給された電圧を電圧発生回路(DC/DCコ
ンバータ)41に入力し、正負の選択電圧−VL、+V
Hを生成させている。ここに正負というのは、何かの絶
対電位、例えばこの表示装置が組み込まれるパーソナル
コンピュータの電源に対して規定された電位のことでは
なく、非走査時の走査電圧Vmに対する電位で表現して
いる。選択電圧に基づいてこれを抵抗分割しバッファ4
5を介することによって信号電圧+Vb、−Vbと中間
電圧Vmを得る。但し、この抵抗分割は、図1の如く1
本の直列接続された抵抗で全てのバイアス電圧を得ても
よいが、複数の抵抗分割回路で得てもよい。図の例では
全ての電圧を単一の抵抗分割回路で直接得るのではな
く、中間電圧Vmは抵抗Rmによって得、信号電圧−V
bは信号電圧+Vbの反転で得るなど間接的に得てい
る。このように信号電圧+Vbを中間電圧Vmに対して
反転させて信号電圧−Vbを得ることによって、中間電
圧Vmに対する信号電圧+Vbの変動分だけ信号電圧−
Vbに反映させることができるので、大変好ましい。ま
たこの結果、信号電圧の中心と選択電圧の中心が、いず
れも中間電圧Vmとなるように設定され好ましい。
This power supply circuit 44 is used as it is as the drive voltage Vi for the scanning circuit 22 and the signal circuit 33 when the power supplied from the personal computer in which this display device is incorporated is a 0-5 volt voltage system. Alternatively, the voltage generation circuit (DC / DC converter) 41 may obtain a voltage of 0-5 volt system again if necessary. On the other hand, the supplied voltage is input to the voltage generation circuit (DC / DC converter) 41 to select positive and negative selection voltages -VL, + V.
H is being generated. Here, the positive / negative is not an absolute potential of something, for example, a potential regulated with respect to the power supply of a personal computer in which this display device is incorporated, and is expressed by a potential with respect to the scanning voltage Vm during non-scanning. . This is resistance-divided based on the selection voltage and the buffer 4
The signal voltages + Vb and -Vb and the intermediate voltage Vm are obtained by passing through 5. However, this resistance division is 1 as shown in FIG.
All the bias voltages may be obtained by the series-connected resistors, but may be obtained by a plurality of resistance division circuits. In the illustrated example, not all the voltages are directly obtained by a single resistance division circuit, but the intermediate voltage Vm is obtained by the resistor Rm and the signal voltage −V is obtained.
b is obtained indirectly by inverting the signal voltage + Vb. In this way, the signal voltage + Vb is inverted with respect to the intermediate voltage Vm to obtain the signal voltage −Vb, so that the signal voltage −Vb corresponding to the variation of the signal voltage + Vb with respect to the intermediate voltage Vm.
It is very preferable because it can be reflected in Vb. As a result, both the center of the signal voltage and the center of the selection voltage are preferably set to the intermediate voltage Vm.

【0016】この駆動により、走査回路22の集積回路
の出力段は従来の略倍の耐電圧を必要とするが、走査線
数に応じた低速処理であり、出力段で3つの電位のうち
一つを選択するので交流化信号の切り替え時の大きな電
流は発生せず、また従来見られがちだったクロストーク
発生の基になる波形崩れもきわめて生じ難い。一方信号
回路33は上述の例でわずか5ボルト以内という低電圧
しか扱わず、高速駆動に適しているばかりか、集積回路
の面積も小さくできるので、ミリメートル単位で液晶周
辺の幅(通称額縁)を短くするのに凌ぎを削っているこ
とに対しても幅の狭い駆動素子が利用・配置できるので
好ましい。
Due to this driving, the output stage of the integrated circuit of the scanning circuit 22 needs to have a withstand voltage that is approximately double that of the conventional one, but it is a low-speed process corresponding to the number of scanning lines, and one of the three potentials in the output stage. Since one of them is selected, a large current does not occur at the time of switching the AC signal, and the waveform collapse that is the basis of the crosstalk generation, which is often seen in the past, is extremely unlikely to occur. On the other hand, the signal circuit 33 handles only a low voltage of 5 V or less in the above example, and is suitable for high-speed driving, and the area of the integrated circuit can be made small. It is preferable that the driving element having a narrow width can be used and arranged even if the length is shortened and the strength is reduced.

【0017】かかる構成で特徴的なことは、信号回路3
3は、信号電圧±Vbを周囲温度に依存させて供給する
ことであり、そのために電源回路44は、バイアス電圧
のうち信号電圧を得るための抵抗を、温度の上昇に伴っ
てバイアス比が小さくなるように接続された温度依存抵
抗素子で構成したものである。これを単純マトリクス駆
動における液晶セルの特性を、270度液晶分子捩、走
査線数240本のスーパーツイストネマティック液晶セ
ルを例に説明する。液晶セルは、電圧の印加に伴って多
少のヒステリシスを持つ輝度変化を示すが、図4(縦軸
は光透過率T、横軸は駆動電圧V)に示すごとく周囲温
度(LOW,ROOM,HIGH)が高くなると濃度の
変化点が低くなり、従来はこれに追従するような電圧制
御を行ってきた。一方、一定の周囲温度下でバイアス比
を変化させると、図5に示すように、1/14バイアス
駆動では濃度とコントラストを適正にする電圧は低く、
1/18バイアス駆動では電圧が高くなる。さらに汎用
されている特性の安定したサーミスタは温度の上昇に伴
って抵抗値が低下する。そこで本発明のこの実施例で
は、信号電圧±Vbを生成させるために選択電圧+VH
と中間電圧Vmの間に設けられた抵抗分割回路の抵抗R
a、Rbのうち、信号電圧+Vbを得るための抵抗Rb
を温度の上昇に伴ってバイアス比が小さくなるようにサ
ーミスタと固定抵抗とを直列(または並列)接続するこ
とで構成した。
The characteristic of such a configuration is that the signal circuit 3
3 is to supply the signal voltage ± Vb depending on the ambient temperature. Therefore, the power supply circuit 44 uses the resistance for obtaining the signal voltage of the bias voltage, and the bias ratio becomes smaller as the temperature rises. It is composed of temperature-dependent resistance elements connected in such a manner as described above. The characteristics of the liquid crystal cell in the simple matrix drive will be described with reference to a super twist nematic liquid crystal cell having 270 ° liquid crystal molecule twist and 240 scanning lines as an example. The liquid crystal cell shows a change in luminance with some hysteresis with application of a voltage, but as shown in FIG. 4 (vertical axis shows light transmittance T, horizontal axis shows drive voltage V), ambient temperature (LOW, ROOM, HIGH ) Becomes high, the change point of the concentration becomes low, and conventionally, voltage control has been performed so as to follow this. On the other hand, when the bias ratio is changed under a constant ambient temperature, as shown in FIG. 5, in the 1/14 bias drive, the voltage for adjusting the density and the contrast is low,
In 1/18 bias driving, the voltage becomes high. Furthermore, the resistance value of a widely used thermistor with stable characteristics decreases with increasing temperature. Therefore, in this embodiment of the present invention, in order to generate the signal voltage ± Vb, the selection voltage + VH
And the resistance R of the resistance dividing circuit provided between the intermediate voltage Vm and the intermediate voltage Vm.
Of a and Rb, a resistor Rb for obtaining a signal voltage + Vb
Is constructed by connecting a thermistor and a fixed resistor in series (or in parallel) so that the bias ratio becomes smaller as the temperature rises.

【0018】通常室温(+25度C)において、選択電
圧+VH、−VLや信号電圧±Vbの大きさは、電圧平
均化法に準じて求められ、例えば1/240デューティ
の駆動の場合最適バイアス値は1:16.5であり、中
間電圧Vmの電位が供給電圧とフローティングされてい
る場合には、選択電圧30ボルトに対して、供給電源0
ボルトレベルに対する信号電圧は略4.3ボルトと0.
7ボルトである。中間電圧VmとGNDレベルを一致さ
せた方が好ましい場合、選択電圧+VH、−VLは±3
0ボルト、信号電圧±Vbは±1.8ボルトである。本
発明においては室温より低い場合を基準とし、Vm=G
NDのとき、例えば+15度Cで選択電圧±28ボル
ト、信号電圧±1.7ボルトとし、−2〜42度Cの範
囲で見易い濃度とコントラストの表示を得ることができ
た。
Normally, at room temperature (+ 25 ° C.), the magnitudes of the selection voltages + VH, −VL and the signal voltages ± Vb are obtained according to the voltage averaging method. For example, in the case of driving at 1/240 duty, the optimum bias value is obtained. Is 1: 16.5, and when the potential of the intermediate voltage Vm is floating with the supply voltage, the supply voltage of 0 is supplied to the selection voltage of 30 volts.
The signal voltage for the volt level is approximately 4.3 volts and 0.
It is 7 volts. When it is preferable to match the intermediate voltage Vm with the GND level, the selection voltages + VH and -VL are ± 3.
0 volt, signal voltage ± Vb is ± 1.8 volt. In the present invention, Vm = G when the temperature is lower than room temperature.
In the case of ND, for example, at +15 degrees C, the selection voltage is ± 28 volts and the signal voltage is ± 1.7 volts, and in the range of −2 to 42 degrees C, it is possible to obtain a display of easy-to-see density and contrast.

【0019】[0019]

【発明の効果】本発明は上述のように、液晶セル毎のし
かも使用環境に依存した濃度調整を煩雑に行う必要がな
く、しかも走査回路は正負の選択電圧を走査電圧として
用い、画信号に応じて選択電圧の中間値近傍の2種類の
信号電圧を用いるので、画信号が著しく増加しても信号
回路は低電圧で負担は少なく高速処理できる。従って温
度変化に敏感なスーパーツイストネマティック液晶セル
などであっても、少なくとも使用者が日常機器に向かう
室温状態では、表示を見易い状態を保って使用すること
ができた。
As described above, according to the present invention, it is not necessary to complicate the density adjustment for each liquid crystal cell and depending on the use environment, and the scanning circuit uses the positive and negative selection voltages as the scanning voltage to generate the image signal. Accordingly, since two kinds of signal voltages in the vicinity of the intermediate value of the selection voltage are used, even if the image signal is remarkably increased, the signal circuit is low in voltage and the burden is small and high-speed processing is possible. Therefore, even in the case of a super twist nematic liquid crystal cell which is sensitive to temperature change, it was possible to use the display while keeping the display easy to see, at least in a room temperature state in which the user faces everyday equipment.

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

【図1】液晶表示装置のブロック図である。FIG. 1 is a block diagram of a liquid crystal display device.

【図2】本発明実施例の液晶表示装置のブロック図であ
る。
FIG. 2 is a block diagram of a liquid crystal display device according to an embodiment of the present invention.

【図3】aは交流化信号及び走査回路と信号回路の出力
電圧の駆動波形図で、bは液晶に印加される電圧の駆動
波形図である。
3A is a drive waveform diagram of an alternating signal and an output voltage of a scanning circuit and a signal circuit, and b is a drive waveform diagram of a voltage applied to a liquid crystal. FIG.

【図4】液晶セルの温度に関する特性図である。FIG. 4 is a characteristic diagram regarding temperature of a liquid crystal cell.

【図5】液晶セルのバイアス比に関する特性図である。FIG. 5 is a characteristic diagram regarding a bias ratio of a liquid crystal cell.

【符号の説明】[Explanation of symbols]

11 液晶セル 22 走査回路 33 信号回路 44 電源回路 11 liquid crystal cell 22 scanning circuit 33 signal circuit 44 power supply circuit

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 互いに直交する電極群を有する液晶セル
と、該液晶セルの一方の電極群の所定の電極に正負の選
択電圧のいずれかを選択して走査電圧として供給する走
査回路と、前記液晶セルの他方の電極群に前記走査回路
の正の選択電圧と負の選択電圧の中間値近傍の信号電圧
を画信号に応じて選択的に与える信号回路と、前記走査
回路と前記信号回路に所定の値の電圧を供給する電源回
路とを具備した液晶表示装置において、前記信号回路
は、前記信号電圧を周囲温度に依存させて供給すること
を特徴とする液晶表示装置。
1. A liquid crystal cell having electrode groups orthogonal to each other, a scanning circuit which supplies either of positive and negative selection voltages to a predetermined electrode of one electrode group of the liquid crystal cell and supplies the selected scanning voltage as a scanning voltage, A signal circuit for selectively applying to the other electrode group of the liquid crystal cell a signal voltage in the vicinity of an intermediate value between the positive selection voltage and the negative selection voltage of the scanning circuit according to an image signal, and the scanning circuit and the signal circuit. A liquid crystal display device comprising a power supply circuit for supplying a voltage of a predetermined value, wherein the signal circuit supplies the signal voltage depending on an ambient temperature.
【請求項2】 互いに直交する電極群を有する液晶セル
と、該液晶セルの一方の電極群の所定の電極に選択電圧
を走査電圧として与える走査回路と、前記液晶セルの他
方の電極群に信号電圧を画信号に応じて与える信号回路
と、前記走査回路と前記信号回路に所定のバイアス値の
電圧と各回路の駆動電圧を供給する電源回路とを具備し
た液晶表示装置において、前記電源回路は、前記選択電
圧を抵抗分割によって前記バイアス値の電圧を得、その
うち前記信号電圧を得るための前記抵抗は温度の上昇に
伴ってバイアス比が小さくなるように接続された温度依
存抵抗素子であることを特徴とする液晶表示装置。
2. A liquid crystal cell having mutually orthogonal electrode groups, a scanning circuit for applying a selection voltage as a scanning voltage to a predetermined electrode of one electrode group of the liquid crystal cell, and a signal to the other electrode group of the liquid crystal cell. In a liquid crystal display device including a signal circuit that applies a voltage according to an image signal, a power supply circuit that supplies a voltage of a predetermined bias value and a drive voltage for each circuit to the scanning circuit and the signal circuit, the power supply circuit is , A voltage having the bias value is obtained by resistance division of the selection voltage, and the resistance for obtaining the signal voltage is a temperature-dependent resistance element connected so that the bias ratio becomes smaller as the temperature rises. Liquid crystal display device characterized by.
JP4132396A 1996-02-28 1996-02-28 Liquid crystal display device Pending JPH09230306A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4132396A JPH09230306A (en) 1996-02-28 1996-02-28 Liquid crystal display device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4132396A JPH09230306A (en) 1996-02-28 1996-02-28 Liquid crystal display device

Publications (1)

Publication Number Publication Date
JPH09230306A true JPH09230306A (en) 1997-09-05

Family

ID=12605323

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4132396A Pending JPH09230306A (en) 1996-02-28 1996-02-28 Liquid crystal display device

Country Status (1)

Country Link
JP (1) JPH09230306A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100683519B1 (en) * 1999-12-23 2007-02-15 엘지.필립스 엘시디 주식회사 Circuit And Method for Compensating a Charging Characteristic of Liquid Crystal Panel

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100683519B1 (en) * 1999-12-23 2007-02-15 엘지.필립스 엘시디 주식회사 Circuit And Method for Compensating a Charging Characteristic of Liquid Crystal Panel
US7403186B2 (en) 1999-12-23 2008-07-22 Lg Display Co., Ltd. Charge characteristic compensating circuit for liquid crystal display panel

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