CN104200777A - Pixel circuit as well as driving method, display panel and display device thereof - Google Patents
Pixel circuit as well as driving method, display panel and display device thereof Download PDFInfo
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Abstract
The invention discloses a pixel circuit as well as a driving method, a display panel and a display device thereof. The pixel circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a driving transistor, a first capacitor, a second capacitor and a light-emitting element, through the cooperating driving between all transistors and the two capacitors, the driving current is enabled to be unrelated to the threshold voltage of the driving transistor and the step voltage of the two ends of the light-emitting element finally. According to the pixel circuit as well as the driving method, the display panel and the display device thereof, the influence of undesirable factors is eliminated, the problem that the conventional display device is uneven in light emission is further improved effectively, and the uniformity of luminance and the display effect of the display device are improved.
Description
Technical Field
The invention relates to the technical field of organic light emitting display, in particular to a pixel circuit, a driving method thereof, a display panel and a display device.
Background
With the continuous development of multimedia, Organic Light Emitting Diode (OLED) displays have attracted attention in the display market with advantages of simple structure and excellent operating temperature, contrast, viewing angle, etc. The organic light emitting diode display includes a passive matrix OLED display and an active matrix OLED display, which are widely used due to low power consumption. In practical use, the phenomenon of uneven light emission of the organic light emitting diode display is found.
Disclosure of Invention
In view of the above, the present invention provides a pixel circuit, a driving method thereof, a display panel, and a display device, which eliminate the influence of a threshold voltage by compensating the threshold voltage of a transistor driving an organic light emitting diode, thereby eliminating the phenomenon of non-uniform light emission of a display device.
The technical scheme provided by the invention is as follows:
a pixel circuit, comprising: a first transistor, a second transistor, a third transistor, a fourth transistor, a driving transistor, a first capacitor, a second capacitor, and a light emitting element; wherein,
the driving transistor is used for determining the magnitude of driving current, and the magnitude of the driving current is determined by the gate voltage and the source voltage of the driving transistor;
the first transistor is controlled by a first driving signal and is used for transmitting a power supply signal to the grid electrode of the driving transistor;
the second transistor is controlled by a second driving signal and is used for transmitting the source voltage of the driving transistor to a second plate of the first capacitor and a second plate of a second capacitor, and a first plate of the second capacitor is connected to the power supply signal;
the third transistor is controlled by a third driving signal and is used for transmitting a data signal to the grid electrode of the driving transistor and the first polar plate of the first capacitor;
the fourth transistor is controlled by a fourth driving signal for transmitting the driving current from the driving transistor to the light emitting element;
the cathode of the light emitting element is connected to a cathode low potential and emits light in response to the driving current.
Preferably, a gate electrode of the first transistor is connected to the first driving signal, a first electrode of the first transistor is connected to the power supply signal, and a second electrode of the first transistor is connected to a first node;
a gate electrode of the second transistor is connected to the second driving signal, a first electrode of the second transistor is connected to a third node, and a second electrode of the second transistor is connected to a second node;
a gate electrode of the third transistor is connected to the third driving signal, a first electrode of the third transistor is connected to the data signal, and a second electrode of the third transistor is connected to the first node;
a gate of the fourth transistor is connected to the fourth driving signal, a first electrode of the fourth transistor is connected to the third node, a second electrode of the fourth transistor is connected to an anode of the light emitting element, and a cathode of the light emitting element is connected to the cathode low potential;
the grid electrode of the driving transistor is connected to the first node, the drain electrode of the driving transistor is connected to the power supply signal, and the source electrode of the driving transistor is connected to the third node;
a first plate of the first capacitor is connected to the first node, and a second plate of the first capacitor is connected to the second node; and the number of the first and second groups,
the first plate of the second capacitor is connected to the power signal, and the second plate of the second capacitor is connected to the second node.
Preferably, the driving transistor is an N-type transistor.
Preferably, the first transistor, the second transistor, the third transistor and the fourth transistor are all N-type transistors; or,
the first transistor, the second transistor, the third transistor and the fourth transistor are all P-type transistors.
Preferably, the first transistor, the second transistor, the third transistor, the fourth transistor, and the driving transistor are all thin film transistors or metal-oxide-semiconductor field effect transistors.
Preferably, the light emitting element is an organic light emitting diode.
Accordingly, the present invention also provides a driving method for driving the pixel circuit described above, the driving method including a threshold value capturing step, a data writing step, and a light emitting step, wherein,
transmitting the power signal to a gate and a drain of the driving transistor at the threshold grasping step;
in the data writing step, the data signal is transmitted to a first plate of the first capacitor, and the data signal is transmitted to the source electrode of the driving transistor through the coupling of the first capacitor;
in the light emitting step, the driving transistor generates a driving current to drive the light emitting element to emit light.
Preferably, a gate electrode of the first transistor is connected to the first driving signal, a first electrode of the first transistor is connected to the power supply signal, and a second electrode of the first transistor is connected to a first node;
a gate electrode of the second transistor is connected to the second driving signal, a first electrode of the second transistor is connected to a third node, and a second electrode of the second transistor is connected to a second node;
a gate electrode of the third transistor is connected to the third driving signal, a first electrode of the third transistor is connected to the data signal, and a second electrode of the third transistor is connected to the first node;
a gate of the fourth transistor is connected to the fourth driving signal, a first electrode of the fourth transistor is connected to the third node, a second electrode of the fourth transistor is connected to an anode of the light emitting element, and a cathode of the light emitting element is connected to the cathode low potential;
the grid electrode of the driving transistor is connected to the first node, the drain electrode of the driving transistor is connected to the power supply signal, and the source electrode of the driving transistor is connected to the third node;
a first plate of the first capacitor is connected to the first node, and a second plate of the first capacitor is connected to the second node; and the number of the first and second groups,
a first plate of the second capacitor is connected to the power signal, and a second plate of the second capacitor is connected to the second node; wherein the driving method comprises:
in the threshold value grabbing step, the first transistor and the second transistor are driven to be turned on, the third transistor and the fourth transistor are driven to be turned off at the same time, drain voltages of the first node and the driving transistor are both power supply voltages provided by the power supply signal, the driving transistor is turned on until the second node is turned off when the voltage of the second node is the power supply voltage minus the threshold voltage of the driving transistor, and the first capacitor and the second capacitor are both enabled to store the threshold voltage;
in the data writing step, the third transistor is driven to be turned on, the first transistor and the second transistor are driven to be turned off at the same time, the fourth transistor is kept in a turned-off state, the first node voltage is a data voltage provided by the data signal, and the first capacitor couples the data voltage to the second node;
in the light emitting step, the second transistor and the fourth transistor are driven to be turned on, the third transistor is driven to be turned off at the same time, the turned-off state of the first transistor is maintained, the first capacitor holds the voltage difference between the gate and the source of the driving transistor after the data writing step, and the driving current is determined so as to drive the light emitting element to emit light.
Correspondingly, the invention also provides a display panel comprising the pixel circuit.
Correspondingly, the invention also provides a display device which comprises the display panel.
Compared with the prior art, the technical scheme provided by the invention has at least one of the following advantages:
the invention provides a pixel circuit, a driving method thereof, a display panel and a display device, wherein the pixel circuit comprises: the first transistor, the second transistor, the third transistor, the fourth transistor, the driving transistor, the first capacitor, the second capacitor and the light-emitting element are driven by matching of the transistors and the two capacitors, so that the driving current is unrelated to the threshold voltage of the driving transistor and the cross voltage of the two ends of the light-emitting element, the influence of adverse factors is eliminated, the problem of uneven light emission of the display device is effectively solved, and the light-emitting uniformity and the display effect of the display device are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a pixel circuit in the prior art;
fig. 2 is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure;
FIG. 3 is a timing diagram of driving signals according to an embodiment of the present disclosure;
FIG. 4a is a current path diagram of stage T1 in FIG. 3;
FIG. 4b is a current path diagram of stage T2 in FIG. 3;
fig. 4c is a current path diagram of a stage T3 in fig. 3.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Researchers find that in practical use, the phenomenon of uneven light emission of the organic light emitting diode display is found. Referring to fig. 1, a circuit diagram of a conventional pixel circuit in an organic light emitting diode display is shown, and the conventional pixel circuit mostly adopts a 2T1C structure, that is, includes two transistors and a capacitor. The transistor M20 serves as a current driving transistor for supplying a current for light emission to the organic light emitting diode OLED. The transistor M10 is controlled to be turned on by a signal supplied through the scan line Sn, and a data voltage is stored in the capacitor C by a data voltage supplied through the data line Dm connected to the transistor M10 to control the amount of current of the transistor M20.
In practical work, due to the influence of the manufacturing process, threshold voltages of transistors for driving the organic light emitting diodes in the pixel circuits are different, so that when the same data voltage is applied to a plurality of pixel circuits, currents flowing through the organic light emitting diodes in the plurality of pixel circuits are different, and the luminance (light emission) of a display screen of the display is not uniform.
Based on this, an embodiment of the present application provides a pixel circuit, which is shown in fig. 2 and is a schematic structural diagram of the pixel circuit provided in the embodiment of the present application, wherein the pixel circuit includes:
a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a driving transistor M0, a first capacitor C1, a second capacitor C2, and a light emitting device D, wherein the light emitting device D is an organic light emitting diode; wherein,
the driving transistor M0 is used to determine the magnitude of the driving current, which is determined by the gate and source voltages of the driving transistor M0;
the first transistor M1 is controlled by a first driving signal S1 for transferring the power supply voltage Vpvdd to the gate of the driving transistor M0;
the second transistor M2 is controlled by a second driving signal S2 for transmitting the source voltage of the driving transistor M0 to the second plate of the first capacitor C1 and the second plate of the second capacitor C2, the first plate of the second capacitor C2 is connected to the power supply voltage Vpvdd;
the third transistor M3 is controlled by the third driving signal S3, and is used for transmitting the Data signal Data to the gate of the driving transistor M0 and the first plate of the first capacitor C1;
the fourth transistor M4 is controlled by a fourth driving signal S4 for transmitting the driving current from the driving transistor M0 to the light emitting element D;
the cathode of the light emitting element D is connected to a cathode low potential Pvee and emits light in response to the driving current.
More specifically, referring to fig. 2, in the pixel circuit, the gate of the first transistor M1 is connected to the first driving signal S1, the first electrode of the first transistor M1 is connected to the power supply signal Pvdd, and the second electrode of the first transistor M1 is connected to the first node N1;
a gate electrode of the second transistor M2 is connected to the second driving signal S2, a first electrode of the second transistor M2 is connected to the third node N3, and a second electrode of the second transistor M2 is connected to the second node N2;
a gate electrode of the third transistor M3 is connected to the third driving signal S3, a first electrode of the third transistor M3 is connected to the Data signal Data, and a second electrode of the third transistor M3 is connected to the first node N1;
a gate of the fourth transistor M4 is connected to the fourth driving signal S4, a first electrode of the fourth transistor M4 is connected to the third node N3, a second electrode of the fourth transistor M4 is connected to an anode of the light emitting element D, and a cathode of the light emitting element D is connected to a cathode low potential Pvee;
the gate of the driving transistor M0 is connected to the first node N1, the drain of the driving transistor M0 is connected to the power signal Pvdd, and the source of the driving transistor M0 is connected to the third node N3;
a first plate of the first capacitor C1 is connected to a first node N1, and a second plate of the first capacitor C1 is connected to a second node N2; and the number of the first and second groups,
a first plate of the second capacitor C2 is connected to the power signal Pvdd, and a second plate of the second capacitor C2 is connected to the second node N2.
In the pixel circuit provided in the embodiment corresponding to fig. 2, the driving transistor M0 is an N-type transistor. In addition, as for the types of the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4, any one of the transistors may be an N-type transistor or a P-type transistor, and a specific design is required according to practical applications, and the embodiment of the present application is not limited in particular. However, in the process of manufacturing the pixel circuit, the transistors are of the same type, so that the manufacturing process is simpler and the manufacturing efficiency is higher, and therefore, it is more preferable that the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 are all N-type transistors; or,
the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are all P-type transistors. In addition, with the pixel circuit provided in the embodiment of the present application, the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4, and the driving transistor M0 are all thin film transistors or metal-oxide-semiconductor field effect transistors.
Based on the pixel circuit provided by the present application, the present application further provides a driving method, which is combined with the structure of the pixel circuit provided in fig. 2, wherein the driving method provided by the embodiment of the present application includes: a threshold value grasping step, a data writing step and a light emitting step, wherein,
at the threshold grasping step, the power supply voltage Vpvdd is transmitted to the gate and drain of the driving transistor M0;
in the Data writing step, the Data signal Data is transmitted to the first plate of the first capacitor C1 and coupled through the first capacitor C1, so that the Data signal Data is transmitted to the source of the driving transistor M0;
in the light emitting step, the driving transistor M0 generates a driving current to drive the light emitting element D to emit light.
Specifically, based on the structure of the pixel circuit shown in fig. 2, a more detailed description is given to the driving method provided in the embodiment of the present application with reference to fig. 3 to 4c, where fig. 3 is a timing chart of a driving signal provided in the embodiment of the present application; FIG. 4a is a current path diagram of stage T1 in FIG. 3; FIG. 4b is a current path diagram of stage T2 in FIG. 3; fig. 4c is a current path diagram of a stage T3 in fig. 3. The stage T1 corresponds to the threshold capture step in the driving method, the stage T2 corresponds to the data write step in the driving method, and the stage T3 corresponds to the light emission step in the driving method. In addition, in the driving method provided in the embodiment of the present application, all the transistors of the pixel circuit are N-type transistors, that is, all the driving transistor, the first transistor, the second transistor, the third transistor, and the fourth transistor are N-type transistors.
As can be seen from fig. 2, the gate of the first transistor M1 is connected to the first driving signal S1, the first electrode of the first transistor M1 is connected to the power signal Pvdd, and the second electrode of the first transistor M1 is connected to the first node N1;
a gate electrode of the second transistor M2 is connected to the second driving signal S2, a first electrode of the second transistor M2 is connected to the third node N3, and a second electrode of the second transistor M2 is connected to the second node N2;
a gate electrode of the third transistor M3 is connected to the third driving signal S3, a first electrode of the third transistor M3 is connected to the Data signal Data, and a second electrode of the third transistor M3 is connected to the first node N1;
a gate of the fourth transistor M4 is connected to the fourth driving signal S4, a first electrode of the fourth transistor M4 is connected to the third node N3, a second electrode of the fourth transistor M4 is connected to an anode of the light emitting element D, and a cathode of the light emitting element D is connected to a cathode low potential Pvee;
the gate of the driving transistor M0 is connected to the first node N1, the drain of the driving transistor M0 is connected to the power signal Pvdd, and the source of the driving transistor M0 is connected to the third node N3;
a first plate of the first capacitor C1 is connected to a first node N1, and a second plate of the first capacitor C1 is connected to a second node N2; and the number of the first and second groups,
a first plate of the second capacitor C2 is connected to the power supply signal Pvdd, and a second plate of the second capacitor C2 is connected to the second node N2; the driving method comprises the following steps:
in a threshold grabbing step T1, the first transistor M1 and the second transistor M2 are driven to be turned on, the third transistor M3 and the fourth transistor M4 are driven to be turned off, the drain voltages of the first node N1 and the driving transistor M0 are both power voltages provided by the power voltage Vpvdd, the driving transistor M0 is driven to be turned on until the voltage of the second node N2 is the power voltage minus the threshold voltage Vth of the driving transistor M0, and the first capacitor C1 and the second capacitor C2 both store the threshold voltage Vth;
specifically, referring to fig. 3 and 4a, in the threshold grabbing step T1, the drain voltage of the driving transistor M0 is the power supply voltage Vpvdd provided by the power supply signal Pvdd, the first driving signal S1 is at a high level, the first transistor M1 is driven to be turned on, and the power supply voltage Vpvdd is transmitted to the first node N1 through the first transistor M1, so that the voltage of the first node N1 (i.e., the gate voltage of the driving transistor M0) is the power supply voltage Vpvdd provided by the power supply signal Pvdd; the second driving signal S2 is at high level, driving the second transistor M2 to turn on; the third driving signal S3 is at low level, driving the third transistor M3 to turn off; the fourth driving signal S4 is low, driving the fourth transistor M4 to turn off.
At this time, in the threshold grabbing step T1, since the gate voltage and the drain voltage of the driving transistor M0 are both power voltages, the driving transistor M0 is turned on, until the voltage of the second node N2 (since the second transistor M2 turns on the second node N2 and the third node N3, that is, the voltage of the second node N2 is the source voltage of the driving transistor M0) becomes the power voltage Vpvdd minus the threshold voltage Vth of the driving transistor M0, the driving transistor M0 is turned off, and at this time, the first capacitor C1 and the second capacitor C2 both store the threshold voltage Vth of the driving transistor M0.
In the Data writing step T2, the third transistor M3 is driven to be turned on, the first transistor M1 and the second transistor M2 are driven to be turned off, and the fourth transistor M4 is kept in an off state, the first node N1 is a Data voltage provided by the Data signal Data, and the first capacitor C1 couples the Data voltage to the second node N2;
specifically, referring to fig. 3 and 4b, in the data writing step T2, the first driving signal S1 becomes low level, driving the first transistor M1 to be turned off; the second driving signal S2 goes low, driving the second transistor M2 to turn off; the third driving signal S3 changes to high level to drive the third transistor M3 to turn on, and the voltage of the first node N1 (i.e., the gate voltage of the driving transistor M0) is the Data voltage Vdata provided by the Data signal Data; and, the fourth driving signal S4 is low, driving the fourth transistor M4 to turn off.
At this time, the data voltage of the first node N1 is coupled to the second node N2 by the coupling of the first capacitor C1, so that the voltage of the second node N2 becomes: Vpvdd-Vth + (Vdata-Vpvdd) (C1/(C1+ C2)), i.e., the storage voltage of the first capacitor C1, is: Vdata-Vpvdd + Vth- (Vdata-Vpvdd) (C1/(C1+ C2)).
In the light emitting step T3, the second transistor M2 and the fourth transistor M4 are driven to be turned on, the third transistor M3 is driven to be turned off, the turned-off state of the first transistor M1 is maintained, the first capacitor C1 maintains the voltage difference between the gate and the source of the driving transistor M0 after the data writing step T2, and the driving current is determined to drive the light emitting element D to emit light.
Specifically, referring to fig. 3 and 4c, in the light emitting step T3, the first driving signal S1 is kept at a low level, keeping the driving first transistor M1 in an off state; the second driving signal S2 goes high, driving the second transistor M2 to turn on, so that conduction is made between the second node N2 and the third node N3, i.e., between the gate of the driving transistor M0 and the source of the driving transistor M0; the third driving signal S3 goes low, driving the third transistor M3 to turn off; and, the fourth driving signal S4 becomes high level, driving the fourth transistor M4 to turn on.
At this time, in the light emitting step T3, the voltage of the second node N2 is the same as the voltage of the third node N3, and the voltage of the third node N3 (i.e., the source voltage of the driving transistor M0) is the sum of the cathode low voltage Vpvee provided by the cathode low potential Pvee and the voltage across the two ends of the light emitting element D; since the first capacitor C1 holds the storage voltage in the data writing step T2 so that the voltage of the first node N1 (i.e., the gate voltage of the driving transistor M0) is Vdata-Vpvdd + Vth- (Vdata-Vpvdd) (C1/(C1+ C2)) + Vpvee + Vd, the gate-source voltage Vgs of the driving transistor M0 is the difference between the voltage of the first node N1 and the voltage of the second node N2:
Vgs＝Vdata-Vpvdd+Vth-(Vdata-Vpvdd)(C1/(C1+C2))+Vpvee+Vd-Vpvee-Vd
Vdata-Vpvdd + Vth- (Vdata-Vpvdd) (C1/(C1+ C2)) formula one
Since the driving transistor M0 operates in the saturation region at the light emitting step T3, the driving current Id for driving the light emitting element D to emit light is determined by the voltage difference between the gate and the source of the driving transistor M0, and thus the driving current Id is:
Id＝k(Vgs-Vth)2
＝k[Vdata-Vpvdd+Vth-(Vdata-Vpvdd)(C1/(C1+C2))-Vth]2
＝k[(Vdata-Vpvdd)(C2/(C1+C2))]2formula two
In the second formula, Id is represented as a driving current generated by the driving transistor M0, i.e., a current for driving the light emitting element to emit light; k is a constant; vgs is the voltage difference between the gate and source of the drive transistor M0; vth is the threshold voltage of the driving transistor M0; vdata is a Data voltage supplied by the Data signal Data.
To this end, the driving current Id, which is independent of the threshold voltage Vth of the driving transistor M0 and the voltage Vd across the light emitting element D, is transmitted to the light emitting element D through the fourth transistor M4 to drive the light emitting element D to emit light, so that the light emission of the display device is uniform, and the display effect is improved.
According to the above, the transistors and the two capacitors are driven in different stages in a matched manner, so that the driving current is unrelated to the threshold voltage of the driving transistor and the cross voltage of the two ends of the light-emitting element, the influence of adverse factors is eliminated, the problem of uneven light emission of the display device is effectively solved, and the light-emitting uniformity and the display effect of the display device are improved.
In addition, an embodiment of the present application further provides a display panel, which includes a pixel circuit, where the pixel circuit adopts the pixel circuit described in any one of the above embodiments.
It should be noted that the display panel provided in the present application does not specifically limit the number of pixel circuits, and may be designed according to practical applications.
Finally, an embodiment of the present application further provides a display device, which includes a display panel, where the display panel adopts the display panel described in any of the above embodiments.
The embodiment of the application provides a pixel circuit, a driving method thereof, a display panel and a display device, wherein the pixel circuit comprises: the first transistor, the second transistor, the third transistor, the fourth transistor, the driving transistor, the first capacitor, the second capacitor and the light-emitting element are driven by matching of the transistors and the two capacitors, so that the driving current is unrelated to the threshold voltage of the driving transistor and the cross voltage of the two ends of the light-emitting element, the influence of adverse factors is eliminated, the problem of uneven light emission of the display device is effectively solved, and the light-emitting uniformity and the display effect of the display device are improved.
Claims (10)
1. A pixel circuit, comprising: a first transistor, a second transistor, a third transistor, a fourth transistor, a driving transistor, a first capacitor, a second capacitor, and a light emitting element; wherein,
the driving transistor is used for determining the magnitude of driving current, and the magnitude of the driving current is determined by the gate voltage and the source voltage of the driving transistor;
the first transistor is controlled by a first driving signal and is used for transmitting a power supply signal to the grid electrode of the driving transistor;
the second transistor is controlled by a second driving signal and is used for transmitting the source voltage of the driving transistor to a second plate of the first capacitor and a second plate of a second capacitor, and a first plate of the second capacitor is connected to the power supply signal;
the third transistor is controlled by a third driving signal and is used for transmitting a data signal to the grid electrode of the driving transistor and the first polar plate of the first capacitor;
the fourth transistor is controlled by a fourth driving signal for transmitting the driving current from the driving transistor to the light emitting element;
the cathode of the light emitting element is connected to a cathode low potential and emits light in response to the driving current.
2. The pixel circuit according to claim 1, wherein a gate of the first transistor is connected to the first driving signal, a first electrode of the first transistor is connected to the power supply signal, and a second electrode of the first transistor is connected to a first node;
a gate electrode of the second transistor is connected to the second driving signal, a first electrode of the second transistor is connected to a third node, and a second electrode of the second transistor is connected to a second node;
a gate electrode of the third transistor is connected to the third driving signal, a first electrode of the third transistor is connected to the data signal, and a second electrode of the third transistor is connected to the first node;
a gate of the fourth transistor is connected to the fourth driving signal, a first electrode of the fourth transistor is connected to the third node, a second electrode of the fourth transistor is connected to an anode of the light emitting element, and a cathode of the light emitting element is connected to the cathode low potential;
the grid electrode of the driving transistor is connected to the first node, the drain electrode of the driving transistor is connected to the power supply signal, and the source electrode of the driving transistor is connected to the third node;
a first plate of the first capacitor is connected to the first node, and a second plate of the first capacitor is connected to the second node; and the number of the first and second groups,
the first plate of the second capacitor is connected to the power signal, and the second plate of the second capacitor is connected to the second node.
3. The pixel circuit according to claim 1, wherein the driving transistor is an N-type transistor.
4. The pixel circuit according to claim 3, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are all N-type transistors; or,
the first transistor, the second transistor, the third transistor and the fourth transistor are all P-type transistors.
5. The pixel circuit according to claim 1, wherein the first transistor, the second transistor, the third transistor, the fourth transistor, and the driving transistor are each a thin film transistor or a metal-oxide-semiconductor field effect transistor.
6. The pixel circuit according to claim 1, wherein the light emitting element is an organic light emitting diode.
7. A driving method for a pixel circuit, for driving the pixel circuit according to any one of claims 1 to 6, comprising a threshold value grasping step, a data writing step, and a light emitting step,
transmitting the power signal to a gate and a drain of the driving transistor at the threshold grasping step;
in the data writing step, the data signal is transmitted to a first plate of the first capacitor, and the data signal is transmitted to the source electrode of the driving transistor through the coupling of the first capacitor;
in the light emitting step, the driving transistor generates a driving current to drive the light emitting element to emit light.
8. The driving method according to claim 7, wherein the driving method is a method of driving a motor vehicle according to a driving method of a motor vehicle
The grid electrode of the first transistor is connected to the first driving signal, the first electrode of the first transistor is connected to the power supply signal, and the second electrode of the first transistor is connected to a first node;
a gate electrode of the second transistor is connected to the second driving signal, a first electrode of the second transistor is connected to a third node, and a second electrode of the second transistor is connected to a second node;
a gate electrode of the third transistor is connected to the third driving signal, a first electrode of the third transistor is connected to the data signal, and a second electrode of the third transistor is connected to the first node;
a gate of the fourth transistor is connected to the fourth driving signal, a first electrode of the fourth transistor is connected to the third node, a second electrode of the fourth transistor is connected to an anode of the light emitting element, and a cathode of the light emitting element is connected to the cathode low potential;
the grid electrode of the driving transistor is connected to the first node, the drain electrode of the driving transistor is connected to the power supply signal, and the source electrode of the driving transistor is connected to the third node;
a first plate of the first capacitor is connected to the first node, and a second plate of the first capacitor is connected to the second node; and the number of the first and second groups,
a first plate of the second capacitor is connected to the power signal, and a second plate of the second capacitor is connected to the second node; wherein the driving method comprises:
in the threshold value grabbing step, the first transistor and the second transistor are driven to be turned on, the third transistor and the fourth transistor are driven to be turned off at the same time, drain voltages of the first node and the driving transistor are both power supply voltages provided by the power supply signal, the driving transistor is turned on until the second node is turned off when the voltage of the second node is the power supply voltage minus the threshold voltage of the driving transistor, and the first capacitor and the second capacitor are both enabled to store the threshold voltage;
in the data writing step, the third transistor is driven to be turned on, the first transistor and the second transistor are driven to be turned off at the same time, the fourth transistor is kept in a turned-off state, the first node voltage is a data voltage provided by the data signal, and the first capacitor couples the data voltage to the second node;
in the light emitting step, the second transistor and the fourth transistor are driven to be turned on, the third transistor is driven to be turned off at the same time, the turned-off state of the first transistor is maintained, the first capacitor holds the voltage difference between the gate and the source of the driving transistor after the data writing step, and the driving current is determined so as to drive the light emitting element to emit light.
9. A display panel comprising the pixel circuit according to any one of claims 1 to 6.
10. A display device characterized by comprising the display panel according to claim 9.
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