CN104464630A - Pixel circuit, driving method of pixel circuit and active matrix organic light-emitting display - Google Patents
Pixel circuit, driving method of pixel circuit and active matrix organic light-emitting display Download PDFInfo
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Abstract
The invention provides a pixel circuit, a driving method of the pixel circuit and an active matrix organic light-emitting display. The current output by a fourth thin film transistor serving as a driving element in the pixel circuit is determined by the data voltage provided by a data line and the initialized voltage provided by a third power supply, the voltage of an external power supply is not related to the threshold voltage of the fourth thin film transistor, and therefore the non-uniform luminance caused by the deviation of the threshold voltage and the change of the IR voltage drop can be avoided; even when the low gray-scale of a displayed image is switched into the high gray-scale, the compensation for the IR voltage drop can be achieved; even when the low gray-scale of the displayed image is switched into the high gray-scale, the compensation for the IR voltage drop can be achieved; thus, images uniform in luminance can be displayed through the active matrix organic light-emitting display where the pixel circuit and the driving method of the pixel circuit are adopted.
Description
Technical field
The present invention relates to technical field of flat panel display, particularly a kind of image element circuit and driving method thereof and active matrix/organic light emitting display.
Background technology
Organic light emitting display utilizes Organic Light Emitting Diode (English full name Organic Lighting EmittingDiode, be called for short OLED) show image, it is a kind of display of active illuminating, its display mode and traditional Thin Film Transistor-LCD (English full name Thin Film Transistor liquid crystal display, be called for short TFT-LCD) display mode difference, without the need to backlight, and, have that contrast is high, fast response time, a plurality of advantages such as frivolous.Therefore, organic light emitting display is described as the display of a new generation that can replace Thin Film Transistor-LCD.
According to the difference of type of drive, organic light emitting display is divided into passive-matrix organic light emitting display (English full name Passive Matrix Organic Lighting Emitting Display, be called for short PMOLED) and active matrix organic light-emitting display (English full name Active Matrix Organic Lighting EmittingDisplay, be called for short AMOLED), active matrix organic light-emitting display is also referred to as active matrix/organic light emitting display.
Active matrix/organic light emitting display comprises the pel array that sweep trace, data line and described sweep trace and data line define, and each pixel of described pel array generally includes Organic Light Emitting Diode and for driving the image element circuit of described Organic Light Emitting Diode.Please refer to Fig. 1, it is the structural representation of the image element circuit of the active matrix/organic light emitting display of prior art.As shown in Figure 1, existing image element circuit 10 generally includes switching thin-film transistor T1, drive thin film transistor (TFT) T2 and memory capacitance Cs, the grid of described switching thin-film transistor T1 is connected with sweep trace Sn, the source electrode of described switching thin-film transistor T1 is connected with data line Dm, the grid of described driving thin film transistor (TFT) T2 is connected with the drain electrode of described switching thin-film transistor T1, the source electrode of described driving thin film transistor (TFT) T2 is connected with the first power supply ELVDD by the first power supply cabling (not shown), the drain electrode of described driving thin film transistor (TFT) T2 is connected with the anode of described Organic Light Emitting Diode OLED, the negative electrode of described Organic Light Emitting Diode OLED is connected with second source ELVSS by second source cabling (not shown).
When described image element circuit 10 works, first power supply ELVDD provides power supply malleation Vdd, second source ELVSS provides power supply negative pressure Vss, when opening described switching transistor T1 by sweep trace S (n), the data voltage Vdata that data line provides is stored into memory capacitance Cs via described switching transistor T1, thus control described driving transistors T2 generation current, to drive Organic Light Emitting Diode OLED luminous.Now, the computing formula flowing through the electric current I between described driving transistors T2 source electrode and drain electrode is:
Ion＝K×(Vgs-|Vth|)
2
Wherein, K is that the electron mobility of thin film transistor (TFT), breadth length ratio, unit-area capacitance three are long-pending, and Vgs is the gate source voltage of driving transistors T2, the voltage difference namely between grid and source electrode, and Vth is the threshold voltage of driving transistors T2.
Because the gate source voltage Vgs2 of driving transistors T2 equals the voltage difference between power supply malleation Vdd that the first power supply ELVDD provides and the data voltage Vdata that data line provides, i.e. Vdd-Vdata, the electric current I on therefore flowed through between described driving transistors T2 source electrode and drain electrode can calculate according to following formula:
Ion＝K×(Vdd-Vdata-|Vth|)
2
As can be seen here, the electric current flowing through organic light-emitting diodes OLED pipe can be subject to the threshold voltage vt h of driving transistors T2 and the actual impact being applied to the supply voltage Vdd of described image element circuit 10.When threshold voltage vt h and the power supply malleation Vdd appearance change of driving transistors T2, the electric current flowing through Organic Light Emitting Diode OLED will have greatly changed.
Brightness due to pixel is determined by the electric current I on flowing through Organic Light Emitting Diode, can cause but showing different brightness during the data-signal of pixel for same brightness when therefore change appears in the threshold voltage vt h of driving transistors T2 and power supply malleation Vdd.
At present, due to the restriction of manufacturing process, in active matrix/organic light emitting display, the threshold voltage of the thin film transistor (TFT) of each pixel inevitably there are differences, and causes active matrix/organic light emitting display cannot show the image with uniform luminance.And, because the first power supply cabling connecting described first power supply ELVDD and image element circuit 10 exists certain impedance, the impact that the actual supply voltage Vdd arriving pixel end can be subject to pressure drop (IR Drop) changes, namely when a current flows through, first power supply walks the power supply malleation Vdd that line impedence can affect the described image element circuit 10 of actual arrival, the power supply malleation Vdd causing each image element circuit 10 to receive is inconsistent, and then increases the weight of brightness disproportionation phenomenon.
For this reason, industry proposes the various image element circuit with threshold voltage and IR voltage-drop compensation function.But, although these image element circuits have certain threshold voltage and IR voltage-drop compensation function, find when reality uses, after showing low grey menu, just again cannot realize the compensation of IR pressure drop.Therefore, even if adopt these to have the image element circuit of threshold voltage and IR voltage-drop compensation function, still there is brightness disproportionation phenomenon in active matrix/organic light emitting display.
Base this, how to solve the problem that existing active matrix/organic light emitting display exists brightness disproportionation, the technical matters having become those skilled in the art urgently to be resolved hurrily.
Summary of the invention
The object of the present invention is to provide a kind of image element circuit and driving method thereof and active matrix/organic light emitting display, to solve the problem that existing active matrix/organic light emitting display exists brightness disproportionation.
For solving the problem, the invention provides a kind of image element circuit, comprising:
Organic Light Emitting Diode, is connected between the first power supply and second source;
The first film transistor, is connected between data line and Section Point, and its grid is connected to the second sweep trace;
Second thin film transistor (TFT), be connected to the 3rd between power supply and first node, its grid is connected to the first sweep trace;
3rd thin film transistor (TFT), be connected between the 3rd power supply and described Section Point, its grid receives the first launch-control line;
4th thin film transistor (TFT), be connected between described first power supply and the 3rd node, its grid is connected to described first node;
5th thin film transistor (TFT), be connected between described first node and described 3rd node, its grid is connected to described second sweep trace;
6th thin film transistor (TFT), be connected between described 3rd node and the anode of described Organic Light Emitting Diode, its grid is connected to the second launch-control line; And
Memory capacitance, is connected between described first node and Section Point.
Optionally, described first power supply and second source are used as the driving power of described Organic Light Emitting Diode, and described 3rd power supply is used for providing initialization voltage.
Optionally, described first power supply, second source and the 3rd power supply are all direct voltage sources.
Optionally, described the first film transistor is P-type TFT to the 6th thin film transistor (TFT).
Optionally, described 4th thin film transistor (TFT) is as driving transistors, the data voltage that the electric current that described 4th thin film transistor (TFT) is provided to described Organic Light Emitting Diode is provided by described data line and the initialization voltage that the 3rd power supply provides determine, and the threshold voltage of the first supply voltage provided with described first power supply, second source voltage that second source provides and the 4th thin film transistor (TFT) has nothing to do.
Optionally, described second thin film transistor (TFT) is controlled by the first sweep trace, described the first film transistor and the 5th thin film transistor (TFT) are controlled by the second sweep trace, described 3rd thin film transistor (TFT) is by described first emission control line traffic control, and described 6th thin film transistor (TFT) is by the second emission control line traffic control.
Accordingly, present invention also offers a kind of driving method of image element circuit, the driving method of described image element circuit comprises: the scan period comprises first time period, the second time period, the 3rd time period and the 4th time period, wherein,
In first time period, the sweep signal that first sweep trace provides becomes low level from high level, the sweep signal that second sweep trace provides and the control signal that the first launch-control line provides are high level, the control signal that second launch-control line provides becomes high level from low level, open the second thin film transistor (TFT), by the 3rd power supply, initialization is carried out to first node;
In the second time period, the control signal that the sweep signal that first sweep trace provides, described first launch-control line and the second launch-control line provide is high level, the sweep signal that second sweep trace provides becomes low level from high level, open the first film transistor and the 5th thin film transistor (TFT), while write data voltage, the threshold voltage of the 4th thin film transistor (TFT) is sampled;
In the 3rd time period, the sweep signal that first sweep trace and the second sweep trace provide and the control signal that the second launch-control line provides are high level, the control signal that first launch-control line provides becomes low level from high level, open the 3rd thin film transistor (TFT), by the 3rd power supply, initialization is carried out to Section Point;
In the 4th time period, the sweep signal that first sweep trace and the second sweep trace provide is high level, the control signal that first launch-control line provides is low level, the control signal that second launch-control line provides becomes low level from high level, open the 6th thin film transistor (TFT), described 4th thin film transistor (TFT) output current also drives organic light-emitting diode.
Optionally, the described scan period also comprised for the 5th time period, and described 5th time period is arranged between described first time period and the second time period;
In the 5th time period, the sweep signal that first sweep trace provides becomes high level from low level, the control signal that the sweep signal that second sweep trace provides, the first launch-control line and the second launch-control line provide all keeps high level, close the second thin film transistor (TFT), stop the initialization to described first node.
Optionally, the described scan period also comprised for the 6th time period; Described 6th time period is arranged between described second time period and the 3rd time period;
In the 6th time period, the control signal that the sweep signal that first sweep trace provides, the first launch-control line and the second launch-control line provide all keeps high level, the sweep signal that second sweep trace provides becomes high level from low level, close described the first film transistor and the 5th thin film transistor (TFT), stop write data voltage, disconnect grid and the drain electrode of described 4th thin film transistor (TFT) simultaneously.
Accordingly, present invention also offers a kind of active matrix/organic light emitting display, described active matrix/organic light emitting display comprises image element circuit as above.
In image element circuit provided by the invention and driving method and active matrix/organic light emitting display thereof, the data voltage that the electric current exported as the 4th thin film transistor (TFT) of driving element in described image element circuit is provided by data line and the initialization voltage that the 3rd power supply provides determine, and have nothing to do with the supply voltage of outside and the threshold voltage of described 4th thin film transistor (TFT), therefore, it is possible to avoid the brightness disproportionation caused by threshold voltage deviation and IR change in pressure drop, even if display frame is converted to from low GTG the compensation that high gray also can realize IR pressure drop, even if display frame is converted to from low GTG the compensation that high gray also can realize IR pressure drop, thus, adopt the active square organic light emitting display of described image element circuit and driving method thereof can show the image with uniform luminance.
Accompanying drawing explanation
Fig. 1 is the structural representation of the image element circuit of the active matrix/organic light emitting display of prior art;
Fig. 2 is the structural representation of the image element circuit of the embodiment of the present invention;
Fig. 3 is the sequential chart of the driving method of the image element circuit of the embodiment of the present invention.
Embodiment
A kind of image element circuit proposed the present invention below in conjunction with the drawings and specific embodiments and driving method thereof and active matrix/organic light emitting display are described in further detail.According to the following describes and claims, advantages and features of the invention will be clearer.It should be noted that, accompanying drawing all adopts the form that simplifies very much and all uses non-ratio accurately, only in order to object that is convenient, the aid illustration embodiment of the present invention lucidly.
Please refer to Fig. 2, it is the structural representation of the image element circuit of the embodiment of the present invention.As shown in Figure 2, described image element circuit 20 comprises: Organic Light Emitting Diode OLED, is connected between the first power supply and second source; The first film transistor T1, is connected between data line data and Section Point N2, and its grid is connected to the second sweep trace Sn; Second thin film transistor (TFT) T2, be connected between the 3rd power supply and first node N1, its grid is connected to the first sweep trace Sn-1; 3rd thin film transistor (TFT) T3, be connected between the 3rd power supply and Section Point N2, its grid receives the first launch-control line Em-1; 4th thin film transistor (TFT) T4, be connected between the first power supply and the 3rd node N3, its grid is connected to first node N1; 5th thin film transistor (TFT) T5, be connected between first node N1 and the 3rd node N3, its grid is connected to the second sweep trace Sn; 6th thin film transistor (TFT) T6, be connected between the 3rd node N3 and the anode of Organic Light Emitting Diode OLED, its grid is connected to the second launch-control line Em; Memory capacitance Cst, is connected between first node N1 and Section Point N2.
Concrete, described image element circuit 20 is connected with external power source, and external circuit comprises the first power supply, second source and the 3rd power supply.Described first power supply, second source and the 3rd power supply are all direct voltage sources, wherein, described first power supply is high potential pixel power, for providing the first supply voltage Vdd, described second source is low potential pixel power, for providing second source voltage Vss, described first power supply and second source are used as the driving power of Organic Light Emitting Diode OLED.3rd power supply is generally low level voltage source, for providing initialization voltage Vinit.
In the present embodiment, the magnitude of voltage of described initialization voltage Vinit and the magnitude of voltage of described second source voltage Vss close.
Please continue to refer to Fig. 2, described image element circuit 20 is a kind of 6T1C type circuit structures, and comprise 6 thin film transistor (TFT)s and 1 electric capacity, 6 thin film transistor (TFT)s are P-type TFT.Wherein, the drain electrode of the second thin film transistor (TFT) T2 and the 5th thin film transistor (TFT) T5, the grid of the 4th thin film transistor (TFT) T4 and the upper substrate of memory capacitance Cst are all connected to first node N1, the drain electrode of the first film transistor T1 and the 3rd thin film transistor (TFT) T3, the infrabasal plate of memory capacitance Cst is all connected to Section Point N2, the drain electrode of the 4th thin film transistor (TFT) T4, the source electrode of the 5th thin film transistor (TFT) T5 and the 6th thin film transistor (TFT) T6 is all connected to the 3rd node N3, the grid of described second thin film transistor (TFT) T2 is connected with the first sweep trace Sn-1, described the first film transistor T1 is connected with equal second sweep trace Sn with the grid of the 5th thin film transistor (TFT) T5, the grid of described 3rd thin film transistor (TFT) T3 is connected with the first launch-control line Em-1, described 6th thin film transistor (TFT) T6 is connected with the second launch-control line Em.
As shown in Figure 2, described image element circuit 20 controls the second thin film transistor (TFT) T2 by the first sweep trace Sn-1, the first film transistor T1 and the 5th thin film transistor (TFT) T5 is controlled by the second sweep trace Sn, control the 3rd thin film transistor (TFT) T3 by the first launch-control line Em-1, control the 6th thin film transistor (TFT) T6 by the second launch-control line Em.
When the sweep signal that the first sweep trace Sn-1 provides transits to low level, the second thin film transistor (TFT) T2 conducting, the initialization voltage Vinit that the 3rd power supply provides is applied to first node N1 via the second thin film transistor (TFT) T2.
When the sweep signal that the second sweep trace Sn provides transits to low level, the first film transistor T1 and the equal conducting of the 5th thin film transistor (TFT) T5, grid and the drain electrode of the 4th thin film transistor (TFT) T4 realize short circuit by the 5th thin film transistor (TFT) T5, and the data voltage Vdata that data line data provides simultaneously writes Section Point N2 via the first film transistor T1.
When the control signal that the first launch-control line Em-1 provides transits to low level, the 3rd thin film transistor (TFT) T3 conducting, the initialization voltage Vinit that the 3rd power supply provides is applied to first node N2 via the 3rd thin film transistor (TFT) T3.
When the control signal that the second launch-control line Em provides transits to low level, 6th thin film transistor (TFT) T6 conducting, drive current flows to second source along the first power supply through the path of the 4th thin film transistor (TFT) T4, the 6th thin film transistor (TFT) T6 and Organic Light Emitting Diode OLED, causes Organic Light Emitting Diode OLED to light luminescence.
In the present embodiment, 4th thin film transistor (TFT) T4 is as the driving transistors of pixel, voltage corresponding to first node N1 controls the drive current being provided to described Organic Light Emitting Diode OLED, described Organic Light Emitting Diode OLED sends the light of corresponding brightness according to described drive current, thus display image.Wherein, the data voltage Vdata that the drive current that 4th thin film transistor (TFT) T4 is provided to described Organic Light Emitting Diode OLED is provided by data line data and the initialization voltage Vinit that the 3rd power supply provides determines, and the threshold voltage of the first supply voltage Vdd provided with the first power supply, second source voltage Vss that second source provides and the 4th thin film transistor (TFT) T4 has nothing to do.Therefore, adopt described image element circuit 20 can avoid the brightness disproportionation caused by threshold voltage deviation and the mains voltage variations of thin film transistor (TFT), and then improve the display quality of display.
Accordingly, present invention also offers a kind of driving method of image element circuit.Incorporated by reference to referring to figs. 2 and 3, the driving method of described image element circuit comprises:
Scan period comprises first time period t1, the second time period t 2, the 3rd time period t 3 and the 4th time period t 4; Wherein,
At first time period t1, the sweep signal that first sweep trace Sn-1 provides becomes low level from high level, the sweep signal that second sweep trace Sn provides and the control signal that the first launch-control line Em-1 provides are high level, the control signal that second launch-control line Em provides becomes high level from low level, open the second thin film transistor (TFT) T2, by the 3rd power supply, initialization is carried out to described first node N1;
In the second time period t 2, the control signal that the sweep signal that first sweep trace Sn-1 provides, the first launch-control line Em-1 and the second launch-control line Em provide is high level, the sweep signal that second sweep trace Sn provides becomes low level from high level, open the first film transistor T1 and the 5th thin film transistor (TFT) T5, while write data voltage Vdata, the threshold voltage vt h of the 4th thin film transistor (TFT) T4 is sampled;
In the 3rd time period t 3, the sweep signal that first sweep trace Sn-1 and the second sweep trace Sn provides and the control signal that the second launch-control line Em provides are high level, the control signal that first launch-control line Em-1 provides becomes low level from high level, open the 3rd thin film transistor (TFT) T3, by the 3rd power supply, initialization is carried out to described Section Point N2;
In the 4th time period t 4, the sweep signal that first sweep trace Sn-1 and the second sweep trace Sn provides is high level, the control signal that first launch-control line Em-1 provides keeps low level, the control signal that second launch-control line Em provides becomes low level from high level, open the 6th thin film transistor (TFT) T6, the 4th thin film transistor (TFT) T4 output current also drives described Organic Light Emitting Diode OLED luminous.
Concrete, at first time period t1, the sweep signal provided due to the first sweep trace Sn-1 becomes low level from high level, the the second thin film transistor (TFT) T2 controlled by the first sweep trace Sn-1 becomes conducting from cut-off, the initialization voltage Vinit that 3rd power supply provides is provided to first node N1 via the second thin film transistor (TFT) T2 and carries out initialization to first node N1, and after initialization, the voltage of described first node N1 equals initialization voltage Vinit.Because initialization voltage Vinit is close to the second voltage Vss, therefore next phase data can be written into.The sweep signal that first sweep trace Sn-1 provides is from after high level becomes low level, the control signal that second launch-control line Em provides becomes high level from low level, the 6th thin film transistor (TFT) T6 controlled by the second launch-control line Em becomes cut-off from conducting, and therefore described Organic Light Emitting Diode OLED stops luminous.
In the second time period t 2, the sweep signal provided due to the second sweep trace Sn becomes low level from high level, the first film transistor T1 controlled by the second sweep trace Sn and the 5th thin film transistor (TFT) T5 becomes conducting by cut-off, 5th thin film transistor (TFT) T5 conducting makes the grid of the 4th thin film transistor (TFT) T4 and drains by short circuit, and therefore the voltage (i.e. the upper substrate voltage of memory capacitance Cst) of first node N1 becomes Vdd-|Vth|.Simultaneously, due to the first film transistor T1 conducting, the data voltage Vdata that data line data provides is provided to Section Point N2 via the first film transistor T1, and therefore the voltage (i.e. the infrabasal plate voltage of memory capacitance Cst) of Section Point N2 becomes Vdata.Wherein, Vth is the threshold voltage of the 4th thin film transistor (TFT) T4.In other words, in the process the threshold voltage of the 4th thin film transistor (TFT) T4 is stored in memory capacitance Cst, thus completes the sampling to threshold voltage vt h.
In the 3rd time period t 3, the control signal provided due to the first launch-control line Em-1 becomes low level from high level, the 3rd thin film transistor (TFT) T3 controlled by the first launch-control line Em-1 becomes conducting from cut-off, thus, the initialization voltage Vinit that the 3rd power supply provides is provided to Section Point N2 via the 3rd thin film transistor (TFT) T3 and carries out initialization to Section Point N2.After initialization, the voltage (i.e. the infrabasal plate voltage of memory capacitance Cst) of described Section Point N2 equals initialization voltage Vinit.Due to the coupling of memory capacitance Cst, the upper substrate voltage (i.e. the voltage of first node N1) of memory capacitance Cst is Vdd-|Vth|+Vinit-Vdata from Vdd-|Vth| saltus step.
In the 4th time period t 4, the control signal provided due to the second launch-control line Em becomes high level from low level, the 6th thin film transistor (TFT) T6 controlled by the second launch-control line Em becomes conducting from cut-off, the drive current that 4th thin film transistor (TFT) T4 exports flows to second source along the first power supply through the path of the 4th thin film transistor (TFT) T4, the 6th thin film transistor (TFT) T6 and Organic Light Emitting Diode OLED, causes Organic Light Emitting Diode OLED to light luminescence.
Now, the source voltage of the 4th thin film transistor (TFT) T4 equals Vdd, and the grid voltage of the 4th thin film transistor (TFT) T4 equals the voltage of first node N1, i.e. Vdd-|Vth|+Vinit-Vdata.Therefore, the computing formula of the gate source voltage Vgs (voltage difference namely between the grid of described 4th thin film transistor (TFT) T4 and source electrode) of the 4th thin film transistor (TFT) T4 is:
Vgs=(Vdd-|Vth|+Vinit-Vdata)-Vdd formula 1;
And the computing formula flowing through the electric current I on of described Organic Light Emitting Diode OLED is:
Ion=K × (Vgs-Vth)
2formula 2;
Wherein, K is that the electron mobility of thin film transistor (TFT), breadth length ratio, unit-area capacitance three are long-pending.
Can obtain according to formula 1 and formula 2:
Ion=K × (Vinit-Vdata)
2formula 3;
Expression formula based on formula 3 is known, the electric current I on flowing through described Organic Light Emitting Diode OLED is only relevant with data voltage Vdata and initialization voltage Vinit and constant K, and all it doesn't matter with the threshold voltage of the first supply voltage Vdd, second source voltage Vss and the 4th thin film transistor (TFT) T4.Even if cause supply voltage to change because of power line impedance or deviation appears in the threshold voltage of the 4th thin film transistor (TFT) T4, all can not the electric current I on flowing through described Organic Light Emitting Diode OLED be impacted.Therefore, adopt described image element circuit 20 and driving method thereof can realize the compensation of threshold voltage and IR pressure drop, avoid the brightness disproportionation phenomenon walked line impedence and cause because of threshold voltage deviation and power supply.
Described image element circuit 20 realizes the compensation of threshold voltage and IR pressure drop mainly through the work of above four time periods, thus improves brightness uniformity.
Please continue to refer to Fig. 3, the scan period also comprises the 5th time period t 5 and the 6th time period t 6.Wherein, the 5th time period t 5 is arranged between first time period t1 and the second time period t 2, and the 6th time period t 6 is arranged between the second time period t 2 and the 3rd time period t 3.
In the 5th time period t 5, the sweep signal that first sweep trace Sn-1 provides becomes high level from low level, the sweep signal that second sweep trace Sn provides, the control signal that first launch-control line Em-1 and the second launch-control line Em provides all keeps high level, the sweep signal provided due to the first sweep trace Sn-1 becomes high level from low level, the the second thin film transistor (TFT) T2 controlled by the first sweep trace Sn-1 becomes cut-off from conducting, 3rd power supply cannot provide initialization voltage Vinit to first node N1 via the second thin film transistor (TFT) T2, therefore the initialization to described first node N1 is stopped.
In the 6th time period t 6, the sweep signal that first sweep trace Sn-1 provides, the control signal that first launch-control line Em-1 and the second launch-control line Em provides all keeps high level, the sweep signal that second sweep trace Sn provides becomes high level from low level, the sweep signal provided due to the second sweep trace Sn becomes high level from low level, the first film transistor T1 controlled by the second sweep trace Sn and the 5th thin film transistor (TFT) T5 becomes cut-off by conducting, because the first film transistor T1 ends, the data voltage Vdata that data line data provides stops write, simultaneously because the 5th thin film transistor (TFT) T5 ends, the grid of the 4th thin film transistor (TFT) T4 and the separated of drain electrode.
Repeat the course of work of first time period t1, the 5th time period t 5, second time period t 2, the 6th time period t 6, the 3rd time period t 3 and the 4th time period t 4, complete image display function.And, in image display process, carry out between grey menu switching and can not impact the compensate function of IR pressure drop.
If current picture is low grey menu (such as the darkest picture, GTG is 0), because the electric current by power supply cabling is less, now IR pressure drop is less, supply voltage corresponding in pixel is higher, and be assumed to be Vdd1, next frame is converted to high gray picture (such as the brightest picture, GTG is 255), because the electric current by power supply cabling is comparatively large, now IR pressure drop is comparatively large, and supply voltage corresponding in pixel is lower, be assumed to be Vdd2, then Vdd1>Vdd2; In next frame picture valve value compensation stage (i.e. the second time period t 2), the grid of the 4th thin film transistor (TFT) T4 and the voltage difference Vgs of source electrode equal Vdd2-(Vdd1-|Vth|+Vinit-Vdata), due to Vdd1>Vdd2 and Vdata>Vinit, therefore Vgs is less than Vth, now the 4th thin film transistor (TFT) T4 is in conducting state, therefore Vdd2 can write the 3rd node N3, and then realizes the compensation of IR pressure drop.
As can be seen here, even if display frame is converted to high gray picture from low grey menu, described image element circuit 20 also can realize the compensation of IR pressure drop.
Accordingly, present invention also offers a kind of active matrix/organic light emitting display, described active matrix/organic light emitting display comprises image element circuit as above.Specifically please refer to above, repeat no more herein.
To sum up, in image element circuit provided by the invention and driving method and active matrix/organic light emitting display thereof, the data voltage that the electric current exported as the 4th thin film transistor (TFT) T4 of driving element in described image element circuit is provided by data line data and the initialization voltage Vinit that the 3rd power supply provides determine, and have nothing to do with the supply voltage of outside and the threshold voltage of described 4th thin film transistor (TFT) T4, therefore, it is possible to avoid the brightness disproportionation caused by threshold voltage deviation and IR change in pressure drop, even if display frame is converted to from low GTG the compensation that high gray also can realize IR pressure drop, thus, adopt the active square organic light emitting display of described image element circuit and driving method thereof can show the image with uniform luminance.
Foregoing description is only the description to present pre-ferred embodiments, any restriction not to the scope of the invention, and any change that the those of ordinary skill in field of the present invention does according to above-mentioned disclosure, modification, all belong to the protection domain of claims.
Claims (10)
1. an image element circuit, is characterized in that, comprising:
Organic Light Emitting Diode, is connected between the first power supply and second source;
The first film transistor, is connected between data line and Section Point, and its grid is connected to the second sweep trace;
Second thin film transistor (TFT), be connected to the 3rd between power supply and first node, its grid is connected to the first sweep trace;
3rd thin film transistor (TFT), be connected between the 3rd power supply and described Section Point, its grid receives the first launch-control line;
4th thin film transistor (TFT), be connected between described first power supply and the 3rd node, its grid is connected to described first node;
5th thin film transistor (TFT), be connected between described first node and described 3rd node, its grid is connected to described second sweep trace;
6th thin film transistor (TFT), be connected between described 3rd node and the anode of described Organic Light Emitting Diode, its grid is connected to the second launch-control line; And
Memory capacitance, is connected between described first node and Section Point.
2. image element circuit as claimed in claim 1, is characterized in that, described first power supply and second source are used as the driving power of described Organic Light Emitting Diode, and described 3rd power supply is used for providing initialization voltage.
3. image element circuit as claimed in claim 1, it is characterized in that, described first power supply, second source and the 3rd power supply are all direct voltage sources.
4. image element circuit as claimed in claim 1, it is characterized in that, described the first film transistor is P-type TFT to the 6th thin film transistor (TFT).
5. image element circuit as claimed in claim 1, it is characterized in that, described 4th thin film transistor (TFT) is as driving transistors, the data voltage that the electric current that described 4th thin film transistor (TFT) is provided to described Organic Light Emitting Diode is provided by described data line and the initialization voltage that the 3rd power supply provides determine, and the threshold voltage of the first supply voltage provided with described first power supply, second source voltage that second source provides and the 4th thin film transistor (TFT) has nothing to do.
6. image element circuit as claimed in claim 1, it is characterized in that, described second thin film transistor (TFT) is controlled by the first sweep trace, described the first film transistor and the 5th thin film transistor (TFT) are controlled by the second sweep trace, described 3rd thin film transistor (TFT) is by described first emission control line traffic control, and described 6th thin film transistor (TFT) is by the second emission control line traffic control.
7. a driving method for the image element circuit according to any one of claim 1 to 6, is characterized in that, the scan period comprises first time period, the second time period, the 3rd time period and the 4th time period, wherein,
In first time period, the sweep signal that first sweep trace provides becomes low level from high level, the sweep signal that second sweep trace provides and the control signal that the first launch-control line provides are high level, the control signal that second launch-control line provides becomes high level from low level, open the second thin film transistor (TFT), by the 3rd power supply, initialization is carried out to first node;
In the second time period, the control signal that the sweep signal that first sweep trace provides, described first launch-control line and the second launch-control line provide is high level, the sweep signal that second sweep trace provides becomes low level from high level, open the first film transistor and the 5th thin film transistor (TFT), while write data voltage, the threshold voltage of the 4th thin film transistor (TFT) is sampled;
In the 3rd time period, the sweep signal that first sweep trace and the second sweep trace provide and the control signal that the second launch-control line provides are high level, the control signal that first launch-control line provides becomes low level from high level, open the 3rd thin film transistor (TFT), by the 3rd power supply, initialization is carried out to Section Point;
In the 4th time period, the sweep signal that first sweep trace and the second sweep trace provide is high level, the control signal that first launch-control line provides is low level, the control signal that second launch-control line provides becomes low level from high level, open the 6th thin film transistor (TFT), described 4th thin film transistor (TFT) output current also drives organic light-emitting diode.
8. the driving method of image element circuit as claimed in claim 7, it is characterized in that, the described scan period also comprised for the 5th time period, and described 5th time period is arranged between described first time period and the second time period;
In the 5th time period, the sweep signal that first sweep trace provides becomes high level from low level, the control signal that the sweep signal that second sweep trace provides, the first launch-control line and the second launch-control line provide all keeps high level, close the second thin film transistor (TFT), stop the initialization to described first node.
9. the driving method of image element circuit as claimed in claim 7, it is characterized in that, the described scan period also comprised for the 6th time period; Described 6th time period is arranged between described second time period and the 3rd time period;
In the 6th time period, the control signal that the sweep signal that first sweep trace provides, the first launch-control line and the second launch-control line provide all keeps high level, the sweep signal that second sweep trace provides becomes high level from low level, close described the first film transistor and the 5th thin film transistor (TFT), stop write data voltage, disconnect grid and the drain electrode of described 4th thin film transistor (TFT) simultaneously.
10. an active matrix/organic light emitting display, is characterized in that, comprising: the image element circuit according to any one of claim 1 to 6.
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Effective date of registration: 20201210 Address after: No.146 Tianying Road, high tech Zone, Chengdu, Sichuan Province Patentee after: Chengdu CHENXIAN photoelectric Co.,Ltd. Address before: 215300 building 4, No.1 Longteng Road, Kunshan Development Zone, Suzhou City, Jiangsu Province Patentee before: KunShan Go-Visionox Opto-Electronics Co.,Ltd. |