JPH0574569A - Driving device of thin film el and its driving method - Google Patents
Driving device of thin film el and its driving methodInfo
- Publication number
- JPH0574569A JPH0574569A JP25601891A JP25601891A JPH0574569A JP H0574569 A JPH0574569 A JP H0574569A JP 25601891 A JP25601891 A JP 25601891A JP 25601891 A JP25601891 A JP 25601891A JP H0574569 A JPH0574569 A JP H0574569A
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- Japan
- Prior art keywords
- voltage
- tft
- driving
- thin film
- gate voltage
- 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.)
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- Dot-Matrix Printers And Others (AREA)
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
- Electroluminescent Light Sources (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Control Of El Displays (AREA)
Abstract
Description
【０００１】[0001]
【産業上の技術分野】本発明は、アクティブマトリック
スＥＬ表示装置、電子式印字装置の露光系に用いられる
ＥＬイメージバーなどにおける薄膜ＥＬの駆動方法に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a thin film EL in an EL image bar used in an exposure system of an active matrix EL display device or an electronic printing device.
【０００２】[0002]
【従来の技術】”A ６×６-in20lpi Electroluminescen
t Display Panel,”（T.P.Blody,et al,IEEE,Trans.Ele
ctron Devices, Vol.ED-22,No-9,Sept.1975,pp.739-74
9）や”DESIGN OF A PROTOTYPE ACTIVE MATRIX CdSe Ｔ
ＦＴ ADRESSEDＥＬ DISPLAY,”（J.Vanfleteren,et a
l.,Eurodisplay 1990,pp.216ー219）に示される従来の
薄膜ＥＬの１ビットの駆動回路は図１０の回路構成を持
つものであり、ソースにデータ信号（Ｖda）が供給され
る書き込み用ＴＦＴ（１）のドレーンに信号保持用コン
デンサ（２）が接続され、書き込み用ＴＦＴのドレーン
と信号保持用コンデンサの接続点がＥＬ駆動用ＴＦＴ
（４）のゲートに接続されている。ＥＬ駆動信号（５）
とＥＬ発光素子（３）とＥＬ駆動用ＴＦＴは直列に接続
され閉回路を構成している。このようなＥＬ駆動回路に
おいて、書き込み用ＴＦＴ（１）を介して蓄積用コンデ
ンサ（２）に書き込み保持されたデータ信号電圧（Ｖd
a）に対応する電圧がＥＬ駆動用ＴＦＴ（４）のオン／
オフを制御し、駆動信号（５）とでＥＬ素子の（３）発
光が制御される。ここで、データ信号電圧（Ｖda）に対
するＥＬ発光素子（３）の輝度特性は、図４に示す様に
発光開始輝度（Ｌoff）から飽和輝度（Ｌon）まで急峻
に立ち上がるものであり、変調データ電圧（Ｖdhm）の
範囲で非発光時の輝度（Ｌoff）から飽和輝度（Ｌon）
までの間で階調表示を得るときに、この変調データ電圧
幅（Ｖdhm）は狭く、マトリックス回路のクロストー
ク、データ書き込み保持回路のバラツキ等によるデータ
信号電圧（Ｖda）の誤差分を受け、所望の階調レベルを
安定した均一な輝度の表示画面で得ることが困難である
欠点があった。2. Description of the Related Art "A 6 × 6-in20lpi Electroluminescen
t Display Panel, ”(TPBlody, et al, IEEE, Trans.Ele
ctron Devices, Vol.ED-22, No-9, Sept.1975, pp.739-74
9) and "DESIGN OF A PROTOTYPE ACTIVE MATRIX CdSe T
FT ADRESSEDEL DISPLAY, ”(J.Vanfleteren, et a
l., Eurodisplay 1990, pp.216-219), the conventional 1-bit driving circuit of the thin film EL has the circuit configuration of FIG. 10, and is for writing in which the data signal (Vda) is supplied to the source. The signal holding capacitor (2) is connected to the drain of the TFT (1), and the connection point between the drain of the writing TFT and the signal holding capacitor is the EL driving TFT.
It is connected to the gate of (4). EL drive signal (5)
The EL light emitting element (3) and the EL driving TFT are connected in series to form a closed circuit. In such an EL drive circuit, the data signal voltage (Vd which is written and held in the storage capacitor (2) through the writing TFT (1) is held.
The voltage corresponding to a) turns on / off the EL driving TFT (4).
The off state is controlled, and the light emission of the EL element (3) is controlled by the drive signal (5). Here, the luminance characteristic of the EL light emitting element (3) with respect to the data signal voltage (Vda) is such that as shown in FIG. 4, it rapidly rises from the light emission start luminance (Loff) to the saturation luminance (Lon), and the modulation data voltage In the range of (Vdhm), the luminance (Loff) to the saturation luminance (Lon) when not emitting light
This is because the modulation data voltage width (Vdhm) is narrow when a grayscale display is obtained, and it receives the error of the data signal voltage (Vda) due to the crosstalk of the matrix circuit, the variation of the data write / hold circuit, etc. However, it is difficult to obtain the gradation level of (3) on a display screen with stable and uniform brightness.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、薄膜ＥＬの
駆動方法において、マトリックス回路のクロストーク、
データ信号書き込み保持回路のバラツキ等によるデータ
信号の誤差分に対する許容量が大きな、所望の階調レベ
ルを安定した均一な表示画面で得ることを目的とする。DISCLOSURE OF THE INVENTION The present invention provides a method for driving a thin film EL, wherein crosstalk of a matrix circuit,
An object of the present invention is to obtain a desired gradation level on a stable and uniform display screen, which has a large allowance for an error amount of a data signal due to variations in the data signal write / hold circuit.
【０００４】[0004]
【課題を解決するための手段】発光信号に応じて蓄積用
コンデンサを充電する第１のＴＦＴと、前記蓄積用コン
デンサからの電圧に応じてスイッチング動作しＥＬ素子
とＧＮＤとの接続を制御することで前記ＥＬ素子の発光
を制御する第２のＴＦＴとを有する薄膜ＥＬの駆動装置
において、第２のＴＦＴとＧＮＤとの間に前記蓄積コン
デンサからの電圧に応じて前記ＥＬ素子の駆動電流を抑
制する電流制御抵抗を挿入する。A first TFT that charges a storage capacitor according to a light emission signal, and a switching operation according to a voltage from the storage capacitor to control connection between an EL element and GND. In a device for driving a thin film EL having a second TFT for controlling light emission of the EL element, a driving current of the EL element is suppressed according to a voltage from the storage capacitor between the second TFT and GND. Insert the current control resistor.
【０００５】[0005]
【作用】ＥＬ駆動用ＴＦＴとＧＮＤ間にドレイン電流を
抑制する抵抗を挿入することによりＥＬ駆動用ＴＦＴの
ソース電位がドレイン電流の変化に応じて変化し、実質
的にゲート−ソース電圧が変化するので、ゲート電圧が
高くなるに従って電流抑制抵抗に流れるドレイン電流す
なわちＥＬ素子の駆動電流が抑制される。このＥＬ素子
を所望の輝度で発光させるためには、必要な電圧を得る
ところまでゲート電圧を上げねばならず、結果としてＥ
Ｌ素子の非発光輝度から飽和輝度までに対応したゲート
電圧までに電圧幅を拡大することになる。By inserting a resistor that suppresses the drain current between the EL driving TFT and the GND, the source potential of the EL driving TFT changes according to the change of the drain current, and the gate-source voltage substantially changes. Therefore, as the gate voltage increases, the drain current flowing in the current suppressing resistor, that is, the drive current of the EL element is suppressed. In order for this EL element to emit light with a desired brightness, the gate voltage must be raised to the point where a necessary voltage is obtained, and as a result, E
The voltage width is expanded to the gate voltage corresponding to the non-luminous brightness of the L element to the saturated brightness.
【０００６】[0006]
【実施例】第１の実施例 本発明の駆動方法が図１に示される。図１０に示された
ＥＬ駆動回路のＥＬ駆動用ＴＦＴ（４）のソースとＧＮ
Ｄ間に電流抑制用抵抗（６）が挿入されている。ＥＬ素
子（３）の発光層の材料にＺnＳ：Ｍnを用いた場合、駆
動電圧（５）に対する輝度（Ｌ）特性は、図３に示すよ
うに、駆動用ＴＦＴ（４）のゲート電圧（Ｖg）を一定
にして、発光を開始する非発光輝度（Ｌoff）の発光し
きい電圧（Ｖtel）から所望の発光輝度（Ｌon）の電圧
（Ｖpk）までの間で駆動電圧を変化させることで、対応
した輝度が得られる。ここで、駆動電圧（５）が所望の
発光輝度の電圧（Ｖpk）に等しいときに、データ電圧
(Ｖda)をわずかに変化させるだけで輝度が大幅に変化す
る。この輝度特性を図４に示す。図５の駆動タイミング
において、データ電圧（Ｖda）は、書き込み用ＴＦＴ
（１）のゲートに走査電圧（Ｖsc）が印加されると、保
持用コンデンサ（２）に図５（ｄ）のように充電または
放電が行われた後走査電圧が除かれると、書き込み用Ｔ
ＦＴのゲート-ソース間容量と保持用コンデンサとのフ
ィードスルーによってΔＶgh電圧が低下したところで保
持され駆動用ＴＦＴ（４）のゲート電圧（Ｖg）として
作用する。このゲート電圧は、駆動用ＴＦＴのドレイン
電流特性を制御し、ＥＬ素子（３）に印加される駆動電
圧を変化させ、輝度変調を行う。したがって、変調輝度
範囲(ＬoffからＬonまで)に対応する駆動用ＴＦＴ
（４）の電流特性で、そのゲート電圧幅が決定され、こ
れにフィードスルー降下電圧を加えることにより所望の
輝度を得るためのデータ電圧（Ｖda）を求めることがで
きる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment The driving method of the present invention is shown in FIG. Source and GN of the EL driving TFT (4) of the EL driving circuit shown in FIG.
A current suppressing resistor (6) is inserted between D. When ZnS: Mn is used as the material of the light emitting layer of the EL element (3), the luminance (L) characteristic with respect to the driving voltage (5) is as shown in FIG. ) Is kept constant, and the drive voltage is changed from the light emission threshold voltage (Vtel) of non-luminance (Loff) at which light emission starts to the voltage (Vpk) of desired light emission luminance (Lon). The obtained brightness is obtained. Here, when the drive voltage (5) is equal to the voltage (Vpk) of the desired light emission luminance, the data voltage
Even a slight change in (Vda) changes the brightness significantly. This brightness characteristic is shown in FIG. At the driving timing of FIG. 5, the data voltage (Vda) is the writing TFT.
When the scanning voltage (Vsc) is applied to the gate of (1), the holding capacitor (2) is charged or discharged as shown in FIG.
When the ΔVgh voltage is lowered by the feedthrough between the gate-source capacitance of the FT and the holding capacitor, the ΔVgh voltage is held and acts as the gate voltage (Vg) of the driving TFT (4). This gate voltage controls the drain current characteristic of the driving TFT, changes the driving voltage applied to the EL element (3), and performs brightness modulation. Therefore, the driving TFT corresponding to the modulation luminance range (from Loff to Lon)
The gate voltage width is determined by the current characteristic of (4), and the data voltage (Vda) for obtaining the desired brightness can be obtained by adding the feedthrough drop voltage to the gate voltage width.
【０００７】そこで、図２に示すＥＬ駆動用ＴＦＴ
（４）及び電流制御用抵抗（６）とで構成される部分に
おいて、駆動用ＴＦＴ（４）のゲート電圧（Ｖg）に対
する駆動用ＴＦＴ（４）の電流特性ならびにその回路で
駆動したときの輝度特性で以下に説明する。飽和領域に
おけるＴＦＴのドレイン電流（Ｉd）-ゲート電圧（Ｖ
g）特性は以下のようにして求められる。図２に示すＥ
Ｌ駆動部において、まず、電流抑制用抵抗（６）のない
ときのＩd-Ｖg特性は、チャネル幅Ｗ、チャネル長Ｌ、
移動度μ、ゲート絶縁膜容量Ｃi、スレショルド電圧Ｖt
h、について一般に(1)式で表わされる。 Ｉd＝(1/2)(Ｗ／Ｌ)μＣi(Ｖg-Ｖth)2 (1) ここで、電流抑制用抵抗（６）をソースに挿入すると
(1)式は、(2)、(3)式で表わされる。 Ｉd＝(1/2)(Ｗ／Ｌ)μＣi(Ｖg-Ｖth-Ｖs)2 (2) Ｖs＝Ｉd×Ｒs (3) ここでＲsは電流抑制用抵抗値でありＶsはソース電圧
(2)、(3)式をＩdについて解くと、(4)式が得られる。Therefore, the EL driving TFT shown in FIG.
In the portion composed of (4) and the current control resistor (6), the current characteristics of the driving TFT (4) with respect to the gate voltage (Vg) of the driving TFT (4) and the brightness when driven by the circuit. The characteristics will be described below. Drain current (Id) -gate voltage (V
g) Properties are obtained as follows. E shown in FIG.
In the L driving section, first, the Id-Vg characteristics when there is no current suppressing resistor (6) are as follows: channel width W, channel length L,
Mobility μ, gate insulating film capacitance Ci, threshold voltage Vt
h is generally expressed by the equation (1). Id = (1/2) (W / L) μCi (Vg-Vth) 2 (1) Here, if the current suppressing resistor (6) is inserted into the source,
Equation (1) is expressed by equations (2) and (3). Id = (1/2) (W / L) μCi (Vg-Vth-Vs) 2 (2) Vs = Id × Rs (3) where Rs is the resistance value for current suppression and Vs is the source voltage.
By solving equations (2) and (3) for Id, equation (4) is obtained.
【０００８】[0008]
【数１】 [Equation 1]
【０００９】ここで、Ｋ＝(1/2)(Ｗ／Ｌ)μＣiであり、
Ｖg-Ｖth≦０であれば、Ｉd＝０となるから、(4)式で表
わされる特性は、図６に示すように、ゲート電圧が高く
なるに従って電流が抑制されることになる。そのため、
電流抑制用抵抗のないときの特性(1)から電流抑制用抵
抗を挿入した特性(2)になり、飽和輝度および非発光輝
度のときのＥＬ駆動電流（Ｉd）に対応するゲート電圧
（Ｖg）がそれぞれ、Ｖgh1からＶgh1'、Ｖgh2からＶg
h2'に変わる。ここで、(Ｖgh1'-Ｖgh1)＞（Ｖgh2'-Ｖgh
2）となっているから、拡張した変調ゲート電圧幅は、
(Ｖgh1'-Ｖgh1)-(Ｖgh2'-Ｖgh2)になり、ゲート電圧
（Ｖｇ）に対する輝度（Ｌ）は図７に示すように電流抑
制用抵抗（６）のないときの特性曲線（１）から電流抑
制用抵抗を挿入したときの特性曲線（２）に移り、変調
ゲート電圧幅（Ｖghm）を広げることができる。Where K = (1/2) (W / L) μCi,
If Vg−Vth ≦ 0, then Id = 0, so that the characteristic represented by the equation (4) is that the current is suppressed as the gate voltage increases, as shown in FIG. for that reason,
The characteristic (1) when there is no current suppressing resistor is changed to the characteristic (2) in which the current suppressing resistor is inserted, and the gate voltage (Vg) corresponds to the EL drive current (Id) at saturated brightness and non-luminous brightness. Are Vgh 1 to Vgh 1 'and Vgh 2 to Vg, respectively
change to h 2 '. Here, (Vgh 1 '-Vgh 1) > (Vgh 2' -Vgh
2 ), the expanded modulation gate voltage width is
(Vgh 1 '-Vgh 1 )-(Vgh 2 ' -Vgh 2 ), and the brightness (L) with respect to the gate voltage (Vg) is a characteristic curve when there is no current suppressing resistor (6) as shown in FIG. It is possible to move from (1) to the characteristic curve (2) when the current suppressing resistor is inserted, and to widen the modulation gate voltage width (Vghm).
【００１０】第２の実施例 図１０の従来回路の駆動用ＴＦＴ（４）ソースとＧＮＤ
間にそのまま電流抑制用抵抗（６）を挿入すると、図８
に示すように、従来の特性曲線(1)が特性曲線(2)の様に
寝たものとなり駆動用ＴＦＴのドレイン電流（Ｉd）が
減少する方向に作用するため、所望の輝度を得るために
は電流抑制用抵抗を挿入しない場合に比べてデータ電圧
（Ｖda）をさらに上げる必要があるが、これは、データ
ドライバの駆動電圧が高くなり、安価な低電圧ドライバ
の範囲を超える恐れもあるし、消費電力の増大も引き起
こす不都合がある。そこで、図８において、電流制限用
抵抗(６)を挿入することによって同一のゲート電圧（Ｖ
g）を印加してもドレイン電流（Ｉd）は従来の特性曲線
(1)から特性曲線(2)の様に低下してしまうところを、発
光飽和ゲート電圧（Ｖgh1）のところでの従来のドレイ
ン電流（Ｉd）が得られるような特性曲線（３）を得れ
ばデータ電圧を上げることなしに変調ゲート電圧幅（Ｖ
ghm'）を広げることができる。(3)のような特性曲線を
得るためには、駆動用ＴＦＴ（４）のチャネル幅Ｗとチ
ャネル長Ｌの比すなわちＷ／Ｌを大きくすることによ
り、発光飽和ゲート電圧（Ｖgh1）を変えることなく非
発光最大ゲート電圧をＶgh2からＶgh2'にまで低下させ
ることができ、変調ゲート電圧幅Ｖghmを(Ｖgh1-Ｖgh2)
から(Ｖgh1-Ｖgh2')に拡大することができる。この方法
によって、従来と同じ最大データ電圧の範囲で、階調表
示の駆動が可能になる。尚、駆動用TFT（４）のドレイ
ン電流(Ｉd)を増大させる方法として、(1)式によれば、
移動度(μ)またはゲート絶縁膜容量(Ｃi)を大きくする
方法でも可能であるが、これらは、製造プロセス条件の
変更や、薄膜ＥＬの全体構造のデザイン変更を必要と
し、また、制御方法が困難で可変範囲が狭いため、Ｗ／
Ｌのサイズ変更に比べて容易ではない。Second Embodiment Driving TFT (4) source and GND of the conventional circuit of FIG.
If the current suppressing resistor (6) is directly inserted between them, the result shown in FIG.
As shown in Fig. 2, the conventional characteristic curve (1) is laid down like the characteristic curve (2) and the drain current (Id) of the driving TFT acts in the direction of decreasing, so that the desired brightness is obtained. Needs to further increase the data voltage (Vda) as compared with the case where the current suppressing resistor is not inserted, but this may increase the driving voltage of the data driver and may exceed the range of an inexpensive low voltage driver. However, there is an inconvenience that also causes an increase in power consumption. Therefore, in FIG. 8, the same gate voltage (V
Even if g) is applied, the drain current (Id) will be
Where the characteristic curve (2) decreases from ( 1 ), the characteristic curve (3) is obtained so that the conventional drain current (Id) at the emission saturation gate voltage (Vgh 1 ) can be obtained. For example, without increasing the data voltage, the modulation gate voltage width (V
ghm ') can be spread. In order to obtain the characteristic curve as shown in (3), the emission saturation gate voltage (Vgh 1 ) is changed by increasing the ratio of the channel width W and the channel length L of the driving TFT (4), that is, W / L. the non-emission maximum gate voltage can be reduced from Vgh 2 down to Vgh 2 'without, the modulated gate voltage width Vghm (Vgh 1 -Vgh 2)
To (Vgh 1 -Vgh 2 '). By this method, it is possible to drive the gradation display in the same range of the maximum data voltage as the conventional one. As a method of increasing the drain current (Id) of the driving TFT (4), according to the equation (1),
It is possible to increase the mobility (μ) or the gate insulating film capacitance (Ci), but these require changes in the manufacturing process conditions and the design of the entire structure of the thin film EL. It is difficult and the variable range is narrow, so W /
It is not as easy as changing the size of L.
【００１１】[0011]
【発明の効果】本発明によれば、簡単な構成を付加する
だけで、階調表示データ電圧幅を拡大できるため、マト
リックス回路のクロストーク、データ書き込み保持回路
のバラツキ等に起因する誤差分に対する許容幅が拡大で
き、所望の階調レベルを安定した均一な輝度の表示画面
で得ることができる。さらに本発明の第２の実施例によ
れば、発光飽和ゲート電圧（Ｖgh1）を上げることなく
変調ゲート電圧幅（Ｖghm）を広げることができるの
で、従来のデータドライバの最大駆動電圧範囲を超える
ことなく、階調表示の駆動が可能となる。According to the present invention, the gradation display data voltage width can be expanded by simply adding a simple structure. Therefore, it is possible to cope with an error caused by crosstalk of the matrix circuit, variation of the data write / hold circuit, and the like. The allowable range can be expanded, and a desired gradation level can be obtained on a stable and uniform display screen. Further, according to the second embodiment of the present invention, the modulation gate voltage width (Vghm) can be widened without increasing the light emission saturation gate voltage (Vgh 1 ), so that it exceeds the maximum drive voltage range of the conventional data driver. It is possible to drive gradation display without the need.
【図１】 本発明による１画素の駆動回路図。FIG. 1 is a drive circuit diagram of one pixel according to the present invention.
【図２】 ＥＬ駆動用ＴＦＴに電流抑制抵抗を挿入した
ときの特性を説明するための回路構成図。FIG. 2 is a circuit configuration diagram for explaining characteristics when a current suppressing resistor is inserted in an EL driving TFT.
【図３】 ゲート電圧を一定にしたときのＥＬ素子の駆
動電圧に対する輝度特性を示す図。FIG. 3 is a diagram showing luminance characteristics with respect to a drive voltage of an EL element when a gate voltage is constant.
【図４】 駆動電圧を一定にしたときのＥＬ駆動用ＴＦ
Ｔのゲート電圧に対する輝度特性を示す図。FIG. 4 TF for EL driving when the driving voltage is constant
The figure which shows the luminance characteristic with respect to the gate voltage of T.
【図５】 駆動回路の駆動タイミングとゲート電圧の特
性を示す図。FIG. 5 is a diagram showing characteristics of drive timing and gate voltage of a drive circuit.
【図６】 電流抑制抵抗を挿入したときのゲート電圧に
対するドレイン電流特性の変化を示す図。FIG. 6 is a diagram showing changes in drain current characteristics with respect to a gate voltage when a current suppressing resistor is inserted.
【図７】 図６の特性におけるデータ電圧に対する輝度
特性の変化を説明する図。FIG. 7 is a diagram for explaining changes in luminance characteristics with respect to the data voltage in the characteristics of FIG.
【図８】 電流抑制抵抗を挿入し、ＥＬ駆動用ＴＦＴ
（４）のＷ／Ｌを大きくしたときのゲート電圧に対する
電流特性の変化を示す図。FIG. 8 is a TFT for EL drive in which a current suppressing resistor is inserted.
The figure which shows the change of the current characteristic with respect to a gate voltage when W / L of (4) is enlarged.
【図９】 図８の特性におけるデータ電圧に対する輝度
特性の変化を説明する図。9A and 9B are views for explaining changes in luminance characteristics with respect to the data voltage in the characteristics of FIG.
【図１０】 従来の１画素の駆動回路構成図。FIG. 10 is a configuration diagram of a conventional drive circuit for one pixel.
１.書き込み用ＴＦＴ、２.保持用コンデンサ、３.ＥＬ
発光素子、４.ＥＬ駆動用ＴＦＴ、６.電流抑制用抵抗、
５.ＥＬ駆動信号、Ｖda.データ信号、Ｖsc.走査信号、
Ｖg.ゲート電圧、Ｖd.ドレイン電圧、Ｖs.ソース電圧、
ｌd.ドレイン電流、Ｖtel.発光しきい電圧、Ｖpk.発光
時電圧、Ｖmod.変調電圧、Ｌoff.非発光時輝度、Ｌon.
発光時輝度、Ｖdh1.発光飽和データ電圧、Ｖdh2.非発光
最大データ電圧、Ｖdhm.変調データ電圧、Ｖgh1.Ｑdの
発光飽和ゲート電圧、Ｖgh2.Ｑdの非発光最大ゲート電
圧、Ｖghm.Ｑdの変調ゲート電圧、Ｖgh.書き込みデータ
電圧の最大電圧、Ｖg.ＥＬ駆動用ＴＦＴのゲート電圧、
ΔＶgh.フィードスルー降下電圧1. Writing TFT, 2. Holding capacitor, 3. EL
Light emitting element, 4. EL driving TFT, 6. Current suppressing resistor,
5. EL drive signal, Vda. Data signal, Vsc. Scan signal,
Vg. Gate voltage, Vd. Drain voltage, Vs. source voltage,
ld. drain current, Vtel. light emission threshold voltage, Vpk. light emission voltage, Vmod. modulation voltage, Loff. non-light emission luminance, Lon.
Luminance during light emission, Vdh 1. Saturation emission data voltage, Vdh 2. Non-emission maximum data voltage, Vdhm. Modulation data voltage, Vgh 1. Qd emission saturation gate voltage, Vgh 2. Qd non-emission maximum gate voltage, Vghm. Modulation gate voltage of Qd, maximum voltage of Vgh. Write data voltage, Vg. Gate voltage of EL driving TFT,
ΔVgh. Feedthrough drop voltage
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｇ０９Ｇ 3/12 9176−5Ｇ 3/30 Ｚ 9176−5Ｇ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification code Internal reference number FI Technical display location G09G 3/12 9176-5G 3/30 Z 9176-5G
Claims (2)
電する薄膜トランジスタ（ＴＦＴ）からなる第１のスイ
ッチング素子と、前記蓄積用コンデンサからの電圧に応
じてスイッチング動作しエレクロトルミネッセンス素子
（ＥＬ素子）と接地（ＧＮＤ）との接続を制御すること
で前記ＥＬ素子の発光を制御するＴＦＴからなる第２の
スイッチング素子とを有する薄膜ＥＬの駆動装置におい
て、 前記第２のＴＦＴと前記ＧＮＤとの間に前記蓄積コンデ
ンサからの電圧に応じて前記ＥＬ素子の駆動電流を抑制
する電流制御抵抗を挿入することを特徴とする薄膜ＥＬ
の駆動装置。1. A first switching element composed of a thin film transistor (TFT) that charges a storage capacitor according to a light emission signal, and an electroluminescence element (EL element) that performs a switching operation according to a voltage from the storage capacitor. In a thin film EL drive device having a second switching element formed of a TFT that controls light emission of the EL element by controlling a connection between the second TFT and the ground (GND), between the second TFT and the GND. A thin film EL, characterized in that a current control resistor for suppressing the drive current of the EL element according to the voltage from the storage capacitor is inserted in
Drive.
電する薄膜トランジスタ（ＴＦＴ）からなる第１のスイ
ッチング素子と、前記蓄積用コンデンサからの電圧に応
じてスイッチング動作しエレクロトルミネッセンス素子
（ＥＬ素子）と接地（ＧＮＤ）との接続を制御すること
で前記ＥＬ素子の発光を制御するＴＦＴからなる第２の
スイッチング素子とを有する薄膜ＥＬの駆動方法におい
て、 前記第２のＴＦＴと前記ＧＮＤとの間に電流制御抵抗を
挿入することによりゲート電圧が高くなるにしたがって
前記第２のＴＦＴのドレイン電流を抑制し、 前記第２のＴＦＴのドレイン電流を抑制することで前記
第２のＴＦＴの前記ＥＬ素子の輝度が飽和するまでのゲ
ート電圧と非発光時のゲート電圧との差を拡大し、 この拡大した差の間の電圧を選択することで選択した電
圧に応じた輝度を得ることを特徴とする薄膜ＥＬの駆動
方法。2. A first switching element composed of a thin film transistor (TFT) that charges a storage capacitor according to a light emission signal, and an electroluminescence element (EL element) that performs a switching operation according to a voltage from the storage capacitor. In a method of driving a thin film EL having a second switching element including a TFT for controlling light emission of the EL element by controlling a connection between a ground and a ground (GND), a method for driving between the second TFT and the GND. The drain current of the second TFT is suppressed as the gate voltage is increased by inserting a current control resistor into the EL element of the second TFT by suppressing the drain current of the second TFT. The difference between the gate voltage until the brightness of the pixel is saturated and the gate voltage during non-light emission is expanded, and the voltage between this expanded difference is A method of driving a thin film EL, characterized in that the brightness according to the selected voltage is obtained by selecting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25601891A JPH0574569A (en) | 1991-09-09 | 1991-09-09 | Driving device of thin film el and its driving method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25601891A JPH0574569A (en) | 1991-09-09 | 1991-09-09 | Driving device of thin film el and its driving method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0574569A true JPH0574569A (en) | 1993-03-26 |
Family
ID=17286771
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25601891A Pending JPH0574569A (en) | 1991-09-09 | 1991-09-09 | Driving device of thin film el and its driving method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0574569A (en) |
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1991
- 1991-09-09 JP JP25601891A patent/JPH0574569A/en active Pending
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