WO2015192528A1 - 像素电路和显示装置 - Google Patents
像素电路和显示装置 Download PDFInfo
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- WO2015192528A1 WO2015192528A1 PCT/CN2014/087581 CN2014087581W WO2015192528A1 WO 2015192528 A1 WO2015192528 A1 WO 2015192528A1 CN 2014087581 W CN2014087581 W CN 2014087581W WO 2015192528 A1 WO2015192528 A1 WO 2015192528A1
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- 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]
-
- 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]
- G09G3/3225—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
Definitions
- the present disclosure relates to a pixel circuit and a display device.
- OLED Organic light-emitting display
- LCD liquid crystal
- PDA PDA
- digital cameras Pixel driver circuit design is the core technology content of OLED display, which has important research significance.
- OLEDs are current driven and require a constant current to control illumination.
- the threshold voltage of the driving TFT of each pixel has unevenness, which leads to the flow of each The current of the pixel OLED changes to make the display brightness uneven, thereby affecting the display effect of the entire image.
- a pixel circuit generally corresponds to one pixel, and each pixel circuit includes at least one data voltage line, one working voltage line and a plurality of scanning signal lines, which leads to a complicated manufacturing process and does not Conducive to reducing the pixel pitch.
- a pixel circuit including two sub-pixel circuits; each of the sub-pixel circuits includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, and a fifth switch a unit, a driving unit, an energy storage unit, and an electroluminescent unit; and, each of the sub-pixel circuits includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a driving unit, An energy storage unit and an electroluminescence unit; and, the first end of the first switch unit is connected to the working voltage line, and the second end of the first switch unit is connected to the input end of the drive unit, Providing a working voltage to the driving unit under control of a scanning signal line connected to a control end of the first switching unit; a first end of the second switching unit is connected to the working voltage line, and a second end of the second switching unit is connected a second end of the energy storage unit, configured to set
- the second end of the fourth switch unit is connected to the second end of the energy storage unit, and is configured to write the voltage in the data voltage line to the control under the control of the scan signal line connected to the control end of the third switch unit Description a second end of the energy unit; a first end of the fifth switch unit is connected between the output end of the driving unit and the electroluminescent unit, and the second end of the fifth switch unit is grounded for the control end of the fifth switch unit
- the output end of the driving unit is grounded under the control of the inserted scanning signal line; in the two sub-pixel circuits, the first end of the fourth switching unit is connected to the same data voltage line, and the control ends of the first switching unit are connected to the first a scan signal line, the control end of the second switch unit is connected to the second scan signal line, and the control end of the fifth switch unit is connected to the third scan signal line; the third switch unit and the fourth of the first sub-pixel circuit The control ends of the switch unit are all connected to the fourth scan signal line, and the third switch unit of the second sub-
- the switching unit and the driving unit are thin film field effect transistors, and the control ends of the respective switching units are gates of the thin film field effect transistors, and the first ends of the respective switching units are the drains of the thin film field effect transistors, each of which
- the second end of the switching unit is a source of the thin film field effect transistor;
- the control end of the driving unit is a gate of the thin film field effect transistor;
- the input end of the driving unit is a drain of the thin film field effect transistor, and the output end is a thin film The source of the field effect transistor.
- each of the thin film field effect transistors is of an N-channel type.
- the energy storage unit is a capacitor.
- the electroluminescent unit is an organic light emitting diode.
- a display device comprising the pixel circuit of any of the above.
- the two sub-pixel circuits of the pixel circuit are respectively located in two adjacent pixels of the same row.
- the two adjacent pixels are respectively located on both sides of the data voltage line.
- the two adjacent pixels are located on the same side of the data voltage line.
- a pixel circuit and a display device are provided.
- the pixel circuit includes two sub-pixel circuits, each of the sub-pixel circuits including: five switch units, a driving unit, an energy storage unit, and an electroluminescence unit.
- the two sub-pixel circuits are connected to the same first scan signal line, second scan signal line, fourth scan signal line and connected to the same data voltage line.
- the operating current flowing through the OLED device can be unaffected by the threshold voltage of the corresponding driving transistor, and the problem of uneven display brightness due to the threshold voltage drift of the driving transistor is completely solved.
- a compensation circuit is used to complete the driving of two pixels, and two adjacent pixels share a plurality of signal lines, which can reduce the number of signal lines used in the pixel circuit in the display device, reduce the cost of the integrated circuit, and reduce the pixel pitch. Increase pixel density.
- FIG. 1 is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure
- FIG. 2 is a timing diagram of key signals in a pixel circuit according to an embodiment of the present disclosure
- 3(a)-(e) are schematic diagrams showing current flow directions and voltage values of pixel circuits at different timings in an embodiment of the present disclosure
- FIG. 4 is a schematic diagram of a positional relationship between a pixel circuit and a pixel in a display device according to an embodiment of the present disclosure
- FIG. 5 is a schematic diagram of a positional relationship between a pixel circuit and a pixel in a display device according to an embodiment of the present disclosure.
- An embodiment of the present disclosure provides a pixel circuit, as shown in FIG. 1 or FIGS. 3(a)-(e), including: two sub-pixel circuits P1 and P2 having the same structure, where each sub-pixel circuit corresponds to one Pixels; Since the structures of P1 and P2 are the same, the following two sub-pixel circuits will be described only in connection with the structure of P1.
- P1 includes: five switching units T1, T2, T3, T4, T5, one driving unit DT, one energy storage unit C, and one electroluminescent unit L (for convenience of distinction, in Fig. 1 or Fig. 3(a) -(e), the five switching units in P2 are denoted as T1', T2', T3', T4', T5', the drive unit is denoted as DT', the energy storage unit is C', and the electroluminescent unit is L', the same as below; the first end of T1 is connected to the working voltage line V dd , and the second end of T1 is connected to the input end of the DT for controlling under the control of the scanning signal line connected to the control end of T1
- the driving unit DT provides an operating voltage; the first end of T2 is connected to the working voltage line V dd , and the second end of T2 is connected to the second end b1 of C (for P2, the second end of the energy storage unit C' is b2), The second end
- the first end a1 of the energy unit C and the control end of the DT (for P2, the first end of the energy storage unit C' is a2), which is used under the control of the scanning signal line accessed by the control terminal of T3 Drive unit
- the control terminal of the DT is connected to the input end of the driving unit DT, and the voltage of the input end of the driving unit DT is charged and discharged to the energy storage unit C;
- the first end of the T4 is connected to the data voltage line V data , the fourth of the T4
- the second end is connected to the second end b1 of the C for writing the voltage V data in the data voltage line to the second end of the energy storage unit C under the control of the scanning signal line accessed by the control terminal of the T4 B1;
- the first end of T5 is connected between the output end of the DT and the electroluminescent unit L, and the second end of the T5 is grounded, and the driving unit DT is controlled under the control of the scanning signal line connected to the control end of the T
- the output end is grounded; and, in the two sub-pixel circuits, the first end of the fourth switch unit is connected to the same data voltage line, and the control end of the first switch unit is connected to the first scan signal line Em2, and the second switch unit is The control terminal is connected to the second scan signal line Em1, and the control end of the fifth switch unit is connected to the third scan signal line Scan[3]; the third switch unit T3 and the fourth switch unit T4 of the first sub-pixel circuit P1
- the control terminals are all connected to the fourth scanning signal line Scan[1], and the second sub-pixel is electrically 'And the fourth switching element T4' control terminal of the third switch T3 of each access unit P2 fifth scanning signal line Scan [2].
- the two switching units whose control terminals are connected to the same scanning signal line should be the same channel.
- Types of switches that is, both high-level conduction or low-level conduction, thereby ensuring that the switching units connected to the same scanning signal line are turned on or off in the same state.
- the operating current flowing through the electroluminescent unit can be unaffected by the threshold voltage of the corresponding driving transistor, and the problem of uneven display brightness due to the threshold voltage drift of the driving transistor is completely solved.
- a compensation circuit is used to complete the driving of two pixels, and two adjacent pixels share a plurality of signal lines, which can reduce the number of signal lines in the display device, reduce the cost of the integrated circuit, reduce the pixel pitch, and improve the display device. Pixel density.
- each of the switching units and each of the driving units are thin film field effect transistors (TFTs), and the control terminals of the respective switching units are gates of the thin film field effect transistors, and the first ends of the respective switching units are the drains of the thin film field effect transistors, each of which The second end of the switching unit is the source of the thin film field effect transistor; the control end of the driving unit is the gate of the thin film field effect transistor, the input end of the driving unit is the drain of the thin film field effect transistor, and the output end is The source of the thin film field effect transistor.
- TFTs thin film field effect transistors
- the transistors corresponding to the driving unit and the switching unit herein may be transistors in which the source and the drain are interchangeable, or the first end of each of the switching units and the driving unit may be the drain of the transistor according to the type of conduction. The second end is the source of the transistor.
- all of the thin film field effect transistors are of an N-channel type. Using the same type of transistor, the process can be unified to improve the yield of the product. It can be understood by those skilled in the art that in practical applications, the types of the transistors may not be exactly the same, for example, T1 may be an N-channel transistor, and T2 may be a P-channel transistor, as long as the control terminal can be connected.
- the technical solutions provided by the present application are the same as the on/off states of the two switching units of the same scanning signal line.
- the exemplary embodiments of the present disclosure are not to be construed as limiting the scope of the disclosure.
- the energy storage unit C is a capacitor.
- other components with energy storage functions can be used according to design requirements.
- the electroluminescent unit L may be an organic light emitting diode (OLED).
- OLED organic light emitting diode
- other components having electroluminescence function can also be used according to design requirements.
- the timing chart of the scan signal in the line can be divided into five stages, which are represented in FIG. 2 as the reset stage W1, the first discharge stage W2, the second discharge stage W3, the compensation jump stage W4, and the illumination stage W5, At each stage, the current flow and voltage values of the pixel circuit are as shown in Fig. 3 (a), Fig. 3 (b), Fig. 3 (c), Fig. 3 (d), and Fig. 3 (e), respectively.
- the respective switching units and driving units are further described as N-channel type TFTs.
- the voltage at the point is set to V1.
- V th1 and V th2 are the threshold voltages of DT and DT', respectively.
- I L' K(V dd - V 2 - V L' ) 2 , where V L ' is the potential of the non-ground terminal of the organic light emitting diode L'.
- the operating current flowing through the two electroluminescent units at this time is not affected by the threshold voltage of the driving transistor, and is only related to the data voltage V data at this time.
- the problem that the driving TFT is drifted by the threshold voltage (V th ) due to the process process and long-time operation is completely solved, the influence of the current flowing through the OLED is eliminated, and the normal operation of the electroluminescent unit is ensured.
- the present disclosure also provides a display device including the pixel circuit shown in any of the above.
- the two sub-pixel circuits of the pixel circuit are respectively located in two adjacent pixels of the same row.
- the two adjacent pixels are located on the same side of their corresponding data voltage lines, and FIG. 4 shows the case where two adjacent pixels corresponding to one pixel circuit PU are on the data voltage line V data side thereof. Or, the two adjacent pixels are respectively located on opposite sides of their corresponding data voltage lines, and FIG. 5 shows that two adjacent pixels corresponding to one pixel circuit PU are on both sides of their corresponding data voltage lines V data Case.
- the display device can be any product or component having display function such as electronic paper, mobile phone, tablet computer, television, display, notebook computer, digital photo frame, navigator, and the like.
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Abstract
一种像素电路和显示装置,像素电路包括两个子像素电路(P1,P2),每个子像素电路(P1,P2)包括五个开关单元(T1,T2,T3,T4,T5,T1',T2',T3',T4',T5')、驱动晶体管(DT,DT')、储能单元(C,C')和电致发光单元(L,L')。两个子像素电路(P1,P2)共用同一数据电压线(Vdata),并共用多条扫描信号线(Em1,Em2,Scan[3])。在像素电路中,流经电致发光单元(L,L')的工作电流能够不受对应的驱动晶体管(DT,DT')的阈值电压的影响,解决了由于驱动晶体管(DT,DT')的阈值电压漂移导致显示亮度不均的问题。同时使用一个补偿电路来完成两个子像素电路(P1,P2)的驱动,相邻的两个子像素电路(P1,P2)共用多条信号线路,能够缩减显示装置中用于像素电路的信号线路数目,降低集成电路成本,缩减像素间距,提高像素密度。
Description
本公开涉及一种像素电路和显示装置。
有机发光显示器(OLED)是当今平板显示器研究领域的热点之一,与液晶显示器相比,OLED具有低能耗、生产成本低、自发光、宽视角及响应速度快等优点。目前,在手机、PDA、数码相机等显示领域OLED已经开始取代传统的液晶(LCD)显示屏。像素驱动电路设计是OLED显示器核心技术内容,具有重要的研究意义。
与TFT-LCD(薄膜场效应晶体管液晶显示器)利用稳定的电压控制亮度不同,OLED属于电流驱动,需要稳定的电流来控制发光。
由于工艺制程和器件老化等原因,在原始的2T1C驱动电路(包括两个薄膜场效应晶体管和一个电容)中,各像素点的驱动TFT的阈值电压存在不均匀性,这样就导致了流过每个像素点OLED的电流发生变化使得显示亮度不均,从而影响整个图像的显示效果。
并且已知技术中,一个像素电路一般对应于一个像素,每个像素电路都至少包含一条数据电压线、一条工作电压线和多条扫描信号线,这样就导致相应的制作工艺较为复杂,并且不利于缩小像素间距。
发明内容
在本公开的一个实施例中提供了一种像素电路,包括两个子像素电路;每个子像素电路包括:第一开关单元、第二开关单元、第三开关单元、第四开关单元、第五开关单元、驱动单元、储能单元和电致发光单元;并且,每个子像素电路包括:第一开关单元、第二开关单元、第三开关单元、第四开关单元、第五开关单元、驱动单元、储能单元和电致发光单元;并且,第一开关单元的第一端连接工作电压线,第一开关单元的第二端连接驱动单元的输入端,用
于在第一开关单元的控制端所接入的扫描信号线的控制下向所述驱动单元提供工作电压;第二开关单元的第一端连接工作电压线,第二开关单元的第二端连接储能单元的第二端,用于在第二开关单元的控制端所接入的扫描信号线的控制下将所述储能单元的第二端置为工作电压;第三开关单元的第一端连接驱动单元的输入端,第三开关单元的第二端连接储能单元的第一端以及驱动单元的控制端,用于在第三开关单元的控制端所接入的扫描信号线的控制下将所述驱动单元的控制端与所述驱动单元的输入端相连,并使驱动单元的输入端的电压对所述储能单元进行充放电;第四开关单元的第一端连接数据电压线,第四开关单元的第二端连接储能单元的第二端,用于在第三开关单元的控制端所接入的扫描信号线的控制下将所述数据电压线中的电压写入到所述储能单元的第二端;第五开关单元的第一端连接在驱动单元的输出端与电致发光单元之间,第五开关单元的第二端接地,用于在第五开关单元的控制端所接入的扫描信号线的控制下将驱动单元的输出端接地;两个子像素电路中,第四开关单元的第一端连接相同的数据电压线,第一开关单元的控制端均接入第一扫描信号线,第二开关单元的控制端均接入第二扫描信号线,第五开关单元的控制端均接入第三扫描信号线;第一子像素电路的第三开关单元和第四开关单元的控制端均接入第四扫描信号线,第二子像素电路的第三开关单元和第四开关单元的控制端均接入第五扫描信号线。
可替换地,所述开关单元和所述驱动单元为薄膜场效应晶体管,各个开关单元的控制端为薄膜场效应晶体管的栅极,各个开关单元第一端为薄膜场效应晶体管的漏极,各个开关单元第二端为薄膜场效应晶体管的源极;所述驱动单元的控制端为薄膜场效应晶体管的栅极;所述驱动单元的输入端为薄膜场效应晶体管的漏极,输出端为薄膜场效应晶体管的源极。
可替换地,各个薄膜场效应晶体管均为N沟道型。
可替换地,所述储能单元为电容。
可替换地,所述电致发光单元为有机发光二极管。
在本公开的一个实施例中提供了一种显示装置,包括上述任一项所述的像素电路。
可替换地,该显示装置中,像素电路的两个子像素电路分别位于同一行的两个相邻像素内。
可替换地,所述两个相邻像素分别位于所述数据电压线的两侧。
可替换地,所述两个相邻像素位于所述数据电压线的同一侧。
在本公开的另一个实施例中提供了一种像素电路和显示装置,像素电路包括两个子像素电路,每个子像素电路包括:五个开关单元、驱动单元、储能单元和电致发光单元,两个子像素电路连接到相同的第一扫描信号线、第二扫描信号线、第四扫描信号线并连接同一条数据电压线。
在本公开的实施例提供的像素电路中,流经OLED器件的工作电流能够不受对应的驱动晶体管的阈值电压的影响,彻底解决了由于驱动晶体管的阈值电压漂移导致显示亮度不均的问题。同时,使用一个补偿电路来完成两个像素的驱动,相邻的两个像素共用多条信号线路,能够缩减显示装置中用于像素电路的信号线路数目,降低集成电路成本,并缩减像素间距,提高像素密度。
图1为本公开实施例提供的像素电路的结构示意图;
图2为本公开实施例提供的像素电路中关键信号的时序图;
图3(a)-(e)为本公开实施例中的像素电路在不同时序下的电流流向和电压值的示意图;
图4为本公开实施例提供的显示装置中像素电路与像素的一种位置关系的示意图;
图5为本公开实施例提供的显示装置中像素电路与像素的一种位置关系的示意图。
下面结合附图和实施例,对本公开的具体实施方式作进一步描
述。以下实施例仅用于更加清楚地说明本公开的技术方案,而不能以此来限制本公开的保护范围。
本公开实施例提供了一种像素电路,如图1或图3(a)-(e)所示,包括:两个结构相同的子像素电路P1和P2,这里的每个子像素电路对应于一个像素;由于P1和P2的结构相同,以下仅结合P1的结构对两个子像素电路进行说明。
这里的P1包括:五个开关单元T1、T2、T3、T4、T5,一个驱动单元DT,一个储能单元C,一个电致发光单元L(为了方便区分,在图1或图3(a)-(e)中,P2中的五个开关单元分别表示为T1’、T2’、T3’、T4’、T5’,驱动单元表示为DT’、储能单元为C’,电致发光单元为L’,下同);T1的第一端连接工作电压线Vdd,T1的第二端连接DT的输入端,用于在T1的控制端所接入的扫描信号线的控制下向所述驱动单元DT提供工作电压;T2的第一端连接工作电压线Vdd,T2的第二端连接C的第二端b1(对于P2,储能单元C’的第二端为b2),用于在T2的控制端所接入的扫描信号线的控制下将所述储能单元C的第二端b1置为工作电压;T3的第一端连接DT的输入端,T3的第二端连接储能单元C的第一端a1以及DT的控制端(对于P2,储能单元C’的第一端为a2),用于在T3的控制端所接入的扫描信号线的控制下将所述驱动单元DT的控制端与所述驱动单元DT的输入端相连,并使驱动单元DT的输入端的电压对所述储能单元C进行充放电;T4的第一端连接数据电压线Vdata,T4的第二端连接C第二端b1,用于在T4的控制端所接入的扫描信号线的控制下将所述数据电压线中的电压Vdata写入到所述储能单元C的第二端b1;T5的第一端连接到DT的输出端与电致发光单元L之间,T5的第二端接地,用于在T5的控制端所接入的扫描信号线的控制下将驱动单元DT的输出端接地;并且,两个子像素电路中,第四开关单元的第一端连接相同的数据电压线,第一开关单元的控制端均接入第一扫描信号线Em2,第二开关单元的控制端均接入第二扫描信号线Em1,第五开关单元的控制端均接入第三扫描信号线Scan[3];第一子像素电路P1的第三开关单元T3和第四开关单元T4的控制端均接入第四扫描信号线Scan[1],第二子像素电路P2的第三开关
单元T3’和第四开关单元T4’的控制端均接入第五扫描信号线Scan[2]。
可以理解的是,控制端连接到同一扫描信号线的两个开关单元(比如T1与T1’,T2和T2’,T3与T4,T3’与T4’,T5与T5’)应为同一沟道类型的开关,即同为高电平导通或者同为低电平导通,从而保证连接到同一扫描信号线的开关单元的导通或关断状态相同。
本公开实施例提供的像素电路中,流经电致发光单元的工作电流能够不受对应的驱动晶体管的阈值电压的影响,彻底解决了由于驱动晶体管的阈值电压漂移导致显示亮度不均的问题。同时,使用一个补偿电路来完成两个像素的驱动,相邻的两个像素共用多条信号线路,能够缩减显示装置中信号线路的数目,降低集成电路成本,并缩减像素间距,提高显示装置的像素密度。
可替换地,各个开关单元和各个驱动单元为薄膜场效应晶体管TFT,各个开关单元的控制端为薄膜场效应晶体管的栅极,各个开关单元的第一端为薄膜场效应晶体管的漏极,各个开关单元的第二端为薄膜场效应晶体管的源极;所述驱动单元的控制端为薄膜场效应晶体管的栅极,所述驱动单元的输入端为薄膜场效应晶体管的漏极,输出端为薄膜场效应晶体管的源极。
不难理解,这里的驱动单元和开关单元对应的晶体管可以为源漏极可以互换的晶体管,或者根据导通类型的不同,各个开关单元和驱动单元的第一端可能为晶体管的漏极、第二端为晶体管的源极。
进一步地,本公开实施例中,所有各个薄膜场效应晶体管均为N沟道型。使用同一类型的晶体管,能够实现工艺流程的统一,从而提高产品的良品率。本领域技术人员可以理解的是,在实际应用中,各个晶体管的类型也可以不完全相同,比如T1可以为N沟道型晶体管,而T2可以为P沟道型晶体管,只要能够使控制端连接到同一扫描信号线的两个开关单元的导通/关断状态相同,即可实现本申请提供的技术方案,本公开示例性实施方式不应理解为对本公开保护范围的限定。
可替换地,所述储能单元C为电容。当然实际应用中,根据设计需要也可以采用其他具有储能功能的元件。
可替换地,所述电致发光单元L可以为有机发光二极管(OLED)。当然实际应用中,根据设计需要也可以采用其他具有电致发光功能的元件。
下面结合图2和图3(a)-(e)对本公开示例性实施例提供的像素电路的工作原理进行详细说明,如图2所示为本公开提供的像素电路工作时输入到各个扫描信号线中的扫描信号的时序图,可分为五个阶段,在图2中分别表示为重置阶段W1、第一放电阶段W2、第二放电阶段W3,补偿跳变阶段W4,发光阶段W5,在各个阶段,像素电路的电流流向和电压值分别如图3(a)、图3(b)、图3(c)、图3(d)、图3(e)所示。为了方便说明,以各个开关单元和驱动单元为N沟道型TFT进行进一步的阐述。
在重置阶段W1,如图2所示,扫描信号线中,Scan[1]、Scan[2]、Scan[3]和EM2为高电平,Em1为低电平,而数据电压Vdata=V1,V1为有机发光二极管L所对应的电压,此时,除了T2和T2’断开,其余开关均导通,电流流向如图3(a)中的La所示,此时Vdd分向C的a1端充电,将a1端的电压势置为Vdd,并向C’的a2端充电,将a端的电压置为Vdd,同时由于T4和T4’导通,b1点的电压和b2点的电压均被置为V1。
在第一放电阶段W2,如图2所示,扫描信号线中,Scan[1]、Scan[2]、Scan[3]为高电平,EM2和Em1为低电平,数据电压Vdata维持为V1,此时T1、T2、T1’、T2’、DT、DT’均导通,其他TFT关断,电流流向如图3(b)中的Lb1和Lb2所示,此时两个储能单元C和C’分别沿Lb1和Lb2放电,由于T5和T5’的导通使得电流不会通过L和L’,间接降低了两个电致发光单元的损耗。经第一放电阶段后,b1点电势和b2点电势保持不变,a1点电势和a2点电势分别降为Vth1和Vth2,这里的Vth1和Vth2分别为DT和DT’的阈值电压。
在第二放电阶段W3,如图2所示,扫描信号线中,Scan[2],Scan[3]为高电平,Scan[1]、Em1、Em2为低电平,数据电压Vdata为V2,V2为有机发光二极管L’所对应的电压,此时只有P2中的T3’、T4’和DT’导通,电流流向如图3(c)中的Lc所示,此过程与上一过程类似,不同的是仅有P2的储能单元C’放电,放电完成后,b2端的电位会变为V2,
而a2点一直维持Vth2。
在补偿跳变阶段W4,如图2所示,扫描信号线中,Scan[3]和Em1为高电平,其他信号线为低电平,此时仅有T2、T5、T2’、T5’为导通状态,其他TFT为关断状态,电流流向如图3(d)中的Ld所示,此时,b1和b2点接Vdd(电势变化为V1→Vdd、V2→Vdd),由于a1和a2端浮接,储能单元C和C’两端实现电压均等量跳变,C跳变前的压差为Vth1-V1,C’跳变前的压差为Vth2-V2,则跳变后a1点的电势Va1=Vdd+Vth1-V1,a2点的电势Va2=Vdd+Vth2-V2,此过程为发光阶段做准备。
在发光阶段W5,如图2所示,扫描信号线中,仅Em2为高电平,其他信号线均为低电平,此时仅T1、T1’、DT、DT’导通,其他TFT关断,电流流向如图3(e)中的Le所示,Vdd对L和L’供应电流,使L和L’放电。
根据饱和电流公式可知,此时流经L的电流IL=K(VGS–Vth1)2=K(Vdd+Vth1–V1–VL–Vth1)2=K(Vdd–V1–VL)2,其中VL为有机发光二极管L的非接地端的电势。
同理,IL’=K(Vdd–V2–VL’)2,其中VL’为有机发光二极管L’的非接地端的电势。
由上式中可以看到此时流经两个电致发光单元的工作电流不受驱动晶体管阈值电压的影响,只与此时的数据电压Vdata有关。彻底解决了驱动TFT由于工艺制程及长时间的操作造成阈值电压(Vth)漂移的问题,消除其对流经OLED的电流的影响,保证电致发光单元的正常工作。
基于相同的构思,本公开还提供了一种显示装置,包括上述任一项所示的像素电路。
可替换地,该显示装置中,像素电路的两个子像素电路分别位于同一行的两个相邻像素内。
可替换地,所述两个相邻像素位于其对应的数据电压线的同一侧,图4示出了其中一个像素电路PU对应的两个相邻像素在其数据电压线Vdata一侧的情况;或者,所述两个相邻像素分别位于其对应的数据电压线的两侧,图5示出了其中一个像素电路PU对应的两个相邻像
素在其对应的数据电压线Vdata两侧的情况。
显示装置可以为:电子纸、手机、平板电脑、电视机、显示器、笔记本电脑、数码相框、导航仪等任何具有显示功能的产品或部件。
以上所述仅是本公开的优选实施方式,应当指出,对于本技术领域的普通技术人员来说,在不脱离本公开技术原理的前提下,还可以做出若干改进和润饰,这些改进和润饰也应视为本公开的保护范围。
本申请要求于2014年6月18日递交的中国专利申请第201410274188.9号的优先权,在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
Claims (9)
- 一种像素电路,包括两个子像素电路;每个子像素电路包括:第一开关单元、第二开关单元、第三开关单元、第四开关单元、第五开关单元、驱动单元、储能单元和电致发光单元;并且,第一开关单元的第一端连接工作电压线,第一开关单元的第二端连接驱动单元的输入端,用于在第一开关单元的控制端所接入的扫描信号线的控制下向所述驱动单元提供工作电压;第二开关单元的第一端连接工作电压线,第二开关单元的第二端连接储能单元的第二端,用于在第二开关单元的控制端所接入的扫描信号线的控制下将所述储能单元的第二端置为工作电压;第三开关单元的第一端连接驱动单元的输入端,第三开关单元的第二端连接储能单元的第一端以及驱动单元的控制端,用于在第三开关单元的控制端所接入的扫描信号线的控制下将所述驱动单元的控制端与所述驱动单元的输入端相连,并使驱动单元的输入端的电压对所述储能单元进行充放电;第四开关单元的第一端连接数据电压线,第四开关单元的第二端连接储能单元的第二端,用于在第四开关单元的控制端所接入的扫描信号线的控制下将所述数据电压线中的电压写入到所述储能单元的第二端;第五开关单元的第一端连接在驱动单元的输出端与电致发光单元之间,第五开关单元的第二端接地,用于在第五开关单元的控制端所接入的扫描信号线的控制下将驱动单元的输出端接地;并且,两个子像素电路中,第四开关单元的第一端连接相同的数据电压线,第一开关单元的控制端均接入第一扫描信号线,第二开关单元的控制端均接入第二扫描信号线,第五开关单元的控制端均接入第三扫描信号线;第一子像素电路的第三开关单元和第四开关单元的控制端均接入第四扫描信号线,第二子像素电路的第三开关单元和第四开关单元的控制端均接入第五扫描信号线。
- 如权利要求1所述的像素电路,其中,各个开关单元和各个驱动单元为薄膜场效应晶体管,各个开关单元的控制端为薄膜场效应晶体管的栅极,各个开关单元的第一端为薄膜场效应晶体管的漏极,各个开关单元的第二端 为薄膜场效应晶体管的源极;各个驱动单元的控制端为薄膜场效应晶体管的栅极,各个驱动单元的输入端为薄膜场效应晶体管的漏极,各个驱动单元的输出端为薄膜场效应晶体管的源极。
- 如权利要求2所述的像素电路,其中,各个薄膜场效应晶体管均为N沟道型。
- 如权利要求1-3中任一项所述的像素电路,其中,所述储能单元为电容。
- 如权利要求1-4其中任一项所述的像素电路,其中,所述电致发光单元为有机发光二极管。
- 一种显示装置,包括如权利要求1-5任一项所述的像素电路。
- 如权利要求6所述的显示装置,其中,所述像素电路的两个子像素电路分别位于同一行的两个相邻像素内。
- 如权利要求7所述的显示装置,其中,所述两个相邻像素分别位于所述数据电压线的两侧。
- 如权利要求7所述的显示装置,其中,所述两个相邻像素位于所述数据电压线的同一侧。
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JP2009204664A (ja) * | 2008-02-26 | 2009-09-10 | Sony Corp | 表示装置、表示装置の駆動方法および電子機器 |
CN102779834A (zh) * | 2012-05-22 | 2012-11-14 | 友达光电股份有限公司 | 有机发光显示单元结构与有机发光显示单元电路 |
CN103021338A (zh) * | 2012-12-24 | 2013-04-03 | 北京京东方光电科技有限公司 | 像素电路及其驱动方法、显示装置 |
CN103474024A (zh) * | 2013-09-06 | 2013-12-25 | 京东方科技集团股份有限公司 | 一种像素电路及显示器 |
CN203932065U (zh) * | 2014-06-18 | 2014-11-05 | 京东方科技集团股份有限公司 | 像素电路和显示装置 |
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CN104078004B (zh) | 2016-08-31 |
CN104078004A (zh) | 2014-10-01 |
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