CN1720568A - 有机led显示器件及其驱动方法 - Google Patents

有机led显示器件及其驱动方法 Download PDF

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CN1720568A
CN1720568A CNA2003801051759A CN200380105175A CN1720568A CN 1720568 A CN1720568 A CN 1720568A CN A2003801051759 A CNA2003801051759 A CN A2003801051759A CN 200380105175 A CN200380105175 A CN 200380105175A CN 1720568 A CN1720568 A CN 1720568A
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M·T·约翰逊
J·N·胡伯特斯
P·维杰
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Beijing Xiaomi Mobile Software Co Ltd
Koninklijke Philips NV
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    • G—PHYSICS
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    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G—PHYSICS
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    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
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    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3216—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using a passive matrix
    • G—PHYSICS
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    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
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    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
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    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/043—Preventing or counteracting the effects of ageing
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2014—Display of intermediate tones by modulation of the duration of a single pulse during which the logic level remains constant
    • G—PHYSICS
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    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2077—Display of intermediate tones by a combination of two or more gradation control methods
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3275—Details of drivers for data electrodes
    • G09G3/3291—Details of drivers for data electrodes in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

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Abstract

一种用来驱动有机LED显示器件的方法，此有机LED显示器件具有第一和第二电极，将限定了多个发光元件的有机层夹在中间。此方法包含：将降低电极之间短路危险的规定电压范围内的电压施加到发光元件，以及控制所述发光元件的占空比，使所希望的光强从所述发光元件发射。从而借助于避免显示器像素工作于短路机会高的电压范围内而降低了有机LED显示器件的像素中的短路几率。借助于控制发光元件的占空比而补偿了所施加电压的这一限制。

Description

有机LED显示器件及其驱动方法
技术领域
本发明涉及有机LED显示器件的驱动方法，此有机LED显示器件具有第一和第二电极，将例如聚合物(PLED)或小有机分子(OLED)层的有机层夹在中间。
背景技术
有机显示器中的短路由于直接导致像素失效而特别严重。在有机LED器件中，有机层提供了二个电极之间的电隔离，且在工作过程中，此层承受着大电场。同时出现有机层的局部紊乱(颗粒和针孔等)，并由于这些紊乱造成电极之间直接接触而产生局部泄漏电流。
局部泄漏电流耗散的电能引起短路的发展。在显示器的使用期限内，为保持恒定的器件电流所需的电压增大，造成能量耗散增大。这种随寿命的电压增大正是其中恒定器件电流是优选驱动方法的有机LED显示器的特征。
当能量耗散导致局部温度高于分解温度(包括材料的熔点和甚至沸点)时，就出现局部损伤。通常，这种损伤的结果有二个方面。能够导致甚至更大的局部泄漏电流，从而出现新的损伤。用作“熔丝”的各个层无法保持这一泄漏电流。另一方面，此损伤能够导致泄漏电流降低，从而导致局部温度降低。缺陷被中和，直至所施加电场的增大再次导致新的损伤。
发明内容
本发明的目的是降低有机LED显示器中的短路危险。
借助于将降低电极之间短路危险的特定范围内的电压施加到发光元件，并将所述发光元件的占空比控制成从所述发光元件发射所希望的光强，达到了这一目的和其它的目的。
根据本发明，借助于避免使显示器像素工作于短路机会大的电压范围内，降低了有机LED显示器件像素中的短路几率。借助于控制发光元件的占空比，来补偿所施加电压的这一限制。参见例如US6023259可知有机LED的占空比控制本身。
本发明依赖于实现显示器中像素的感观亮度是其发光过程中的亮度以及各个像素发光的时间比率(其“占空比)的函数。因此，倘若占空比可连续变化，则理论上有可能从具有给定实际亮度的像素产生任何感观亮度的像素。因此，这一实现使得能够借助于适当控制占空比而选择任何给定像素的实际工作电压。
研究表明，通常存在着某个上下受限制的电压范围，在此范围内降低了短路的危险。借助于控制显示器中发光元件的占空比，能够将电压保持在此范围内，而不限制发射光强的范围。
在某些情况下，例如当显示黑色图象的情况下，所施加电压有时在临界值以下，短路的危险从而明显地增大。在此情况下，借助于降低像素的占空比，像素的工作电压可以被控制在临界值以上。
在其它的应用中，选择小于100％的占空比作为缺省工作方法。一个例子是视频应用(TV、DVD等)的有源矩阵PLED/OLED显示器，其中，占空比被减小，以便降低运动模糊赝象(所谓“取样保持”赝象)。另一个更普通的例子是减小占空比，以便提高有源矩阵显示器上的亮度均匀性(降低多晶硅TFT中各个晶体管之间的变化对均匀性的影响)。
在此情况下，选择太小的占空比虽然有利于显示器的性能，但可能使显示器中的某些像素(例如一种有色像素)工作于临界值以上的电压，从而明显地增大短路的危险。在此情况下，借助于提高像素的占空比(即使这稍许降低了显示器的性能)，像素的工作电压可以被控制成仍然在临界值以下。
选择缺省占空比小于100％也使得占空比能够随时间逐渐增大。由于所施加电压常常改变，且特别是在有机显示器的使用期限内增大，故这可能是有利的。若已知电压增大的速率(或能够从查表或分析函数中推导)，来替代能够适当地提高占空比，从而使工作电压能够仍然在形成短路的任何临界值以下。
根据一个实施方案，借助于监测显示器中各个像素的平均电压，例如借助于监测显示器的功率耗散，能够做到这一点。在此情况下，将监测实际(平均)电压，从而按需要调整占空比。
根据另一实施方案，显示器中各个或有代表性的像素的电压被监测，从而仅仅需要在临界值被实际达到时提高各个像素的占空比。这确保了显示器总是工作于其最高可能的性能水平下而不增大形成短路的危险。
可以对各个帧控制占空比(单帧占空比)，或对几个帧控制占空比(多帧占空比)。可以在无源以及有源矩阵显示器件中实现后一变化形式。
在有源矩阵显示器中，可以单独地对各个发光元件控制占空比，或一起对几个元件(例如所有元件)控制占空比。前者的实现使得能够得到最佳的调节可能性，而后者实现起来更不复杂，且成本效率更高。
从参照附图更明确描述的优选实施方案中，本发明的这些和其它的情况将变得明显。
附图说明
图1是有机LED显示器中像素的示意透视图。
图2示出了图1中显示器的4个电压区。
图3是根据本发明第一实施方案的像素驱动的示意电路图。
图4是根据本发明第二实施方案的像素驱动的示意电路图。
图5是根据本发明第三实施方案的像素驱动的示意电路图。
具体实施方式
如上所述，本发明基于控制显示器中发光元件的电压，使之保持在降低短路危险的规定电压范围内。以下更详细地来讨论如何规定这一范围。参照图1，示出了具有顶部电极1和底部电极2、以及中间有机(聚合物(PPV)或小有机分子)层3的有机显示器件中的像素。
顶部和底部电极1、2之间的静电吸引力在有机层3初始损伤之后引起物理接触。此力直接涉及所施加的电压(典型为50-100MV/m)以及有机层3的厚度(对于PLED器件，典型为60-120nm)。由于此层厚度基本上恒定，故电压在短路的形成中起重要的作用。
而且发现，当构成的各层之间的附着性很差时，局部放电造成的损伤更为严重。由于各层被挤压到一起，所施加电压引起的静电力导致附着性的人为改善。还证实了电压(静电力)与短路几率之间的相互关系。
除了电压之外，器件电流，或更具体地说，段电流(segmentcurrent)也起重要作用。典型地说，短路是一种比像素小得多的局部现象(典型为1-10μm)。短路只不过是段电流量级的一种持续的稳定或不稳定的大泄漏电流。因此，将恒定的电流馈送到具有短路的段，会导致光的损失，使之稳定或不稳定(闪烁)。
但对于LED层能够维持多大的泄漏电流存在着一定限制，从而限制了能够流过泄漏通道的最大电流(此现象称为“熔断”)。因此，相对于可能的短路，优选具有更短更大的电流脉冲而不是DC电流来发射一定量的光。当像素中脉冲电流对最大泄漏电流的比率：
R PLBD DRIVING = I dev pulse / I ltakage MAX - - - ( 1 )
高时，短路的影响很小。
实验证据还表明，从起始的局部损伤发展到短路依赖于所用的器件电流以及电压。
这可以表示为：
              Pshort＝αAdev       (2)
其中，α是短路几率(Pshort)和器件面积(Adev)之间的比例常数。
在图2中，分别在所施加电压(虚线，11)与短路几率之间、以及脉冲电流(点线，12)与短路几率之间的相互关系中，能够区分4个不同的区域I-IV。不同区域之间的边界13(阴影区)对于不同的聚合物而变化，且还依赖于精确的层组分。
基于测量和上述模型，4个区域的特征如下：
I)在小的电压数值下，实验发现泄漏电流的不稳定性小。静电吸引力仍然太小而不足以引起直接接触。这直接涉及到构成层的弹性性质。而且，耗散能量(～Vappl/Rchannel，其中，Vappl是所施加电压，Rchannel是局部泄漏路径的电阻)太小而不足以引起损伤。
II)在此电压区域中，“熔断”导致强烈的电流不稳定。由电压引起的静电力将阴极向着阳极挤压。但引起的损伤导致新的接触，和因此的损伤等，并且短路扩展。而且，短路的几率典型地随损伤区(泄漏通道)的周长而增大，且由于此电压区中出现的损伤增加而导致此周长的增加，故短路几率也增大。
III)在5-10V之间的电压下，再次观察到短路几率的强烈降低。在一定的电压(VFUSE)以上，不稳定性消失，且泄漏电流减小。人为增大上述各层之间的附着性有利于恢复几率(损伤时的Rchannel的增大)。此第三区域是LED驱动的优选区域。
IV)实验已经发现，对于一定阈值(对于典型为70nm厚的有机器件约为1OV)以上的电压，所有器件都倾向于泄漏电流异常高的情况。这导致短路．显然，局部温度(直接涉及到耗散功率，一Vappl/Rchannel)达到了如此高的数值，以至于其中一个电极也分解，或各层之间的附着性以某种其它的方式(例如气体形成)而断裂。实验还已经发现，这一效应作为电压的函数而开始得非常突然．发现闽值电压(Vth)作为聚合物类型和器件组分的函数而变化。
总之，应该指出的是，对于所施加电压，通常应该满足下列条件：
            VFUSE＜Vappl＜Vth            (3)从而应该满足为了达到低的短路几率所需的方程1所述的器件电流比率的条件， R OLED DROVING > > 1 .
图6示出了根据本发明的方法的一个实施方案．首先，在步骤s1中，确立施加到发光元件的电压是否在规定范围内(方程3)。若不是这样，则在步骤S2中限制谊电压，并在步骤S3中相应地调整占空比。
参照图3-5，上述条件被应用于有源矩阵聚合物LED器件的驱动方案．由于能够自由地选择这种显示器中像素(发光元件)的占空比，故在有源矩阵应用中能够达到上述目的．其理由是有可能设定像素的亮度级(寻址)而无须使像素实际发光。
图3示出了根据本发明的适合于驱动有机发光元件15例如PLED或OLED的有源矩阵电路．此电路具有寻址晶体管11，它能够将数据电压(Vin)写入到储存点12中。此电压确定了驱动晶体管13相对于电源线14的栅电压。若此栅电压大于驱动晶体管13的闽值电压，则电流经由提供在其间的PLED/0LED 15从电源线14流到阴极18。PLED/OLED 15于是产生光。
图3中的电路还包含连接在PLED/0LED 15与驱动晶体管13之间的额外的晶体管16．此晶体管确定0LED/PLED的占空比。仅仅当此晶体管导通时，像素才能够发光。在本实施方案中，借助于确定额外晶体管16处于导通状态的周期，能够修正占空比。晶体管16的栅被连接到电路17用来控制占空比，亦即控制晶体管16打开的帧周期。电路17可以是例如脉冲宽度调制器。
若显示器中所有的占空比晶体管16都被连接到单个控制器17，则有可能联合地修正整个显示器中所有像素的占空比，以便确保安全的像素电压。根据一个优选实施方案，显示器各部分能够具有其单独地设定和借助于单独地提供被寻址的占空比晶体管16(例如每个有色像素一组)修正的占空比。
现在参照图4，示出了适合于实现本发明的像素电路的第二实施方案。相似于图3中各元件的元件具有相同的参考号。根据本实施方案，电源线14配备有相似于图3中电路17的电路21，以便能够调整将电源线设定到高电压的帧周期。由于仅仅当电源被设定为高电压时，像素才能够发光，故此“电源线占空比”又确定了PLED/OLED像素的占空比。根据本实施方案，借助于调节电源线被开通到高电压的帧周期，就能够修正占空比。
若所有的像素都被连接到单个电源线14，则有可能修正整个显示器的占空比，以便确保安全的像素电压。根据一个优选实施方案，显示器各部分能够具有其单独地设定和借助于提供多个电源线(例如每组有色像素一个电源线)进行修正的占空比。
图5示出了用来实现本发明的像素电路的第三实施方案，其中，相似于图3中各元件的元件再次具有相同的参考号。相似于图3中电路17的电路22，被连接到PLED/OLED 15的阴极18。通过这一安排，可以借助于调节PLED/OLED阴极18上的电压，来修正像素的占空比。若阴极电压被设定得高(通常高于电源线电压)，则由于二极管被设定成反向电压，故像素无法发光。因此，根据本实施方案，借助于调节阴极被设定到低电压的帧周期，能够修正占空比。
通常对于有源矩阵PLED/OLED显示器，所有的像素都被连接到单一的阴极连接，因而有可能修正整个显示器的占空比，来保持安全的像素电压。也有可能提供多个阴极(例如每组有色像素一个阴极)，从而使显示器的不同部分能够具有其单独设定和修正的占空比。
虽然在图3-5中作为例子已经说明了最简单的电压寻址的有源矩阵PLED/OLED像素电路，但有可能将相似的措施应用于本技术所知的大量电压与电流寻址的像素电路。此外，从现有技术所知的在有机LED显示器中产生占空比的其它方法，也可以被有利地采用，例如显示器中的像素在每帧中被寻址一次以上的方法、和像素可以被寻址以便在第一子帧周期中产生光的方法，以及被寻址以便在后续的子帧周期中不产生光的方法。
在上述各实施方案中，“占空比”的表述已经被用来仅涉及到每次一帧。但本发明不局限于这种解释，且另一优选实施方案包括在几个帧上的“占空比”的实现，亦即在选择的帧内控制被选择的像素不发光，以便降低总计的发光强度。
在例如进一步降低帧的占空比实际上不合理的情况下，例如在电子设备要求至少一定时间来稳定其工作的情况下，这可能是有利的。在这种情况下，为了达到所希望的感知亮度级，某些亮度较低的像素可能要求在上述临界值其中之一以下的电压。这会增大在这些像素中短路的危险。
在此情况下，可以用这种像素不再被每帧寻址的方式来驱动显示器。例如，当像素激活以实现相同的感知亮度时，借助于每2帧寻址这些像素，将在该帧内要求二倍更高亮度的脉冲。以这种方式，像素将在激活帧期间工作于更高的电压下——高于临界值，短路的危险将再次降低。在其它帧内，像素根本不被驱动，因而将不短路。
当然，若要求进一步增大工作电压，则像素可以甚至更少地被寻址。若仅仅要求小的降低，则像素可以被例如每三帧被寻址二次。
为了使显示器以这种方式工作，将要求少量的数据处理来识别要求这种多帧驱动的像素，并相应地调节驱动信号。
应该指出的是，本发明的这一实施方案不局限于有源矩阵显示器，而是也可以有利地被用于无源矩阵显示器，以便避免亮度较低的像素工作于太低的电压。当无源矩阵用幅度调制驱动方法产生灰度等级时，这更可能是恰当的。其实现可以类似于上面对有源矩阵应用所述的。

Claims (21)

1.一种用来驱动有机LED显示器件的方法，此有机LED显示器件具有第一和第二电极(1，2)，将限定了多个发光元件(15)的有机层(3)夹在中间，所述方法包含：将规定电压范围内的电压施加(S1，S2)到发光元件(15)，在该范围内降低了电极(1，2)之间短路危险，以及控制(S3)所述发光元件(15)的占空比，使所希望的光强从所述发光元件(15)发射。
2.根据权利要求1的方法，其中，所述发光元件的占空比被降低，以便发射所希望的光强而不要求在规定的下限以下的所施加电压。
3.根据权利要求1的方法，其中，所述发光元件的缺省占空比小于100％，且其中所述占空比被增大，以便发射所希望的光强而不要求在规定的上限以上的所施加电压。
4.根据权利要求2或3的方法，还包含：确定为保持所述发光元件中恒定的驱动电流所要求的电压随时间的预期变化，以及相应地调整所述发光元件的占空比。
5.根据权利要求2或3的方法，还包含：监测显示器中的平均像素电压，并根据此平均电压而调整每个发光元件的占空比。
6.根据权利要求2或3的方法，还包含：监测发光元件的电压，并根据此电压而调整所述发光元件的占空比。
7.根据前述权利要求中任何一个的方法，其中，在每个帧上控制所述占空比。
8.根据权利要求1-6的方法，其中，在多个帧上控制占空比。
9.根据前述权利要求中任何一个的方法，其中，所述显示器件是有源矩阵型的。
10.根据权利要求9的方法，其中，对每个发光元件单独地控制占空比。
11.根据权利要求9的方法，其中，对多个发光元件联合地控制占空比。
12.根据权利要求8的方法，其中，显示器件是无源矩阵型的。
13.一种设置为根据前述权利要求之一进行驱动的有机显示器件。
14.一种有机显示器件，它具有第一和第二电极(1，2)，将限定了多个发光元件(15)的有机层(3)夹在中间，此有机显示器件还包含：用来施加电压到发光元件(15)的装置(13，14)，所述电压位于其中降低了电极(1，2)之间短路危险的规定电压范围内，以及用来控制所述发光元件(15)的占空比的装置(16，17；21；22)，使所希望的光强从所述发光元件(15)发射。
15.根据权利要求14的器件，其中，所述控制装置(16，17；21；22)被设置用于降低占空比，以便发射所希望的光强而不要求在规定的下限以下的所施加电压。
16.根据权利要求14的器件，其中，所述控制装置(16，17；21；22)被设置用于维持所述发光元件的缺省占空比小于100％，并增大占空比，以便发射所希望的光强而不要求在规定的上限以上的所施加电压。
17.根据权利要求14-16之一的器件，其中，所述控制装置包含连接在发光元件(15)与电压施加装置(13，14)之间的晶体管(16)，以及连接到晶体管(16)的栅极的占空比控制器(17)。
18.根据权利要求14-16之一的器件，其中，所述控制装置包含连接到电压施加装置(14)的占空比控制器(21)。
19.根据权利要求14-16之一的器件，其中，所述控制装置包含连接到与电压施加装置(13，14)有关的发光元件(15)另一侧的占空比控制器(22)。
20.根据权利要求14-19中任何一个的器件，其中，所述电压施加装置包含电源线(14)和连接在电源线与发光元件(15)之间的驱动晶体管(13)。
21.根据权利要求14-20中任何一个的器件，其中，所述控制装置(16，17；21；22)被设置用于对多个发光元件联合地控制占空比。
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CN109860271A (zh) * 2019-04-16 2019-06-07 京东方科技集团股份有限公司 显示面板及其读取电路、显示终端

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CN100446068C (zh) 2008-12-24
ATE541284T1 (de) 2012-01-15
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