CN104167167A - Pixel circuit, driving method thereof and display device - Google Patents

Abstract

The present invention provides a pixel circuit, including: a first scanning line; a second scanning line; a data line; a first power line; a second power supply line; a third power supply line; the light-emitting element is arranged between the first power line and the second power line; a driving transistor including a gate and disposed between the light emitting element and the first power line; a first switch including a first control electrode connected to the second scan line and connected to the data line; the second switch comprises a second control electrode connected with the first scanning line and is arranged between the third power line and the grid; a third switch including a third control electrode connected to the first scan line and disposed between the first switch and the driving transistor; a fourth switch including a fourth control electrode connected to the first scan line and disposed between the third power line and the driving transistor; the fifth switch is arranged between the first power line and the driving transistor; the first capacitor is connected between the first switch and the grid; and the second capacitor is connected with the first switch, the third switch, the first power line and the first capacitor.

Description

Pixel circuit, driving method thereof, and display device

technical field

The invention relates to the field of driving circuits of display devices, in particular to a pixel circuit capable of compensating a threshold voltage to improve display brightness uniformity, a driving method thereof, and a display device including the pixel circuit.

Background technique

At present, with the continuous development and improvement of display technology, more and more display manufacturers are promoting the research of organic light-emitting displays, because of their technical advantages in light and thin, wide viewing angle, high luminous efficiency and high response speed. In simple terms, an organic light-emitting display displays images by controlling the amount of current flowing through an organic light-emitting diode (OLED) to control the brightness of each pixel. In addition, when a current formed corresponding to the data voltage is supplied to the organic light emitting diode, the organic light emitting diode emits light corresponding to the supplied current. Furthermore, when the data voltage applied to the organic light emitting diode has a certain gray scale value within a predetermined range, the organic light emitting display can display the gray scale of the picture.

Please refer to FIG. 1 , which is a structural diagram of a pixel circuit in a conventional organic light emitting display device. The pixel circuit includes an organic light emitting device OLED, a driving transistor M2, a capacitor Cst and a switching transistor M1. Meanwhile, the pixel circuit is connected to a scan signal Scan (N), a data voltage Vdata, a pixel power supply VDD and an external power supply VSS, wherein VSS is low A voltage different from the pixel power supply voltage (such as ground voltage); the switching transistor M1 has a source connected to the data voltage Vdata, a drain connected to the first end of the capacitor C1, and a gate connected to the scan signal Scan(N); The driving transistor M2 has a source connected to the pixel power supply VDD, a drain connected to the organic light emitting device OLED and a gate connected to the first terminal of the capacitor C1; the second terminal of the capacitor C1 is connected to the source of the driving transistor M2.

When the pixel circuit is working, the driving transistor M2 provides current to the organic light emitting device OLED in response to the gate signal, so that the organic light emitting device OLED emits light. Wherein, the current intensity in the driving transistor M2 can be controlled by the data voltage Vdata and the data signal input by the switching transistor M1. In addition, the capacitor C1 can maintain the voltage between the source and the gate of the driving transistor M2 in response to the data voltage during a predetermined period.

Therefore, when the gate of the switching transistor M1 turns on the switching transistor M1 in response to the scan signal Scan(N), the data voltage Vdata begins to charge the capacitor C1, and then the voltage in the capacitor C1 is applied to the gate of the driving transistor M2 , so that the driving transistor M2 is turned on, so that the current flows through the organic light emitting device OLED to emit light.

The following formula is used to calculate the current supplied from the driving transistor M2 to the organic light emitting device OELD.

$I_{\mathrm{OLED}}=\frac{1}{2}\mathrm{\β}(\mathrm{Vgs}-|\mathrm{Vth}\left|\right)=\frac{1}{2}\mathrm{\β}{(\mathrm{VDD}-\mathrm{Vdata}-|\mathrm{Vth}\left|\right)}^2$ 【Formula A】

Among them, I _OLED is the current flowing through the organic light emitting device OELD; Vgs is the voltage applied between the source and the gate of the driving transistor M2; Vth is the threshold voltage of the driving transistor M2, Vdata is the data voltage; β is the driving transistor M2 gain factor.

Therefore, it can be seen from the above formula A that the current flowing through the organic light emitting device OLED will be affected by the threshold voltage of the driving transistor M2 and change. However, in actual situations, the driving transistors in each pixel circuit may have different threshold voltages from each other. Therefore, due to the deviation of the threshold voltage among the pixels, the current flowing through the organic light-emitting device OLED will be uneven. Thus, the brightness uniformity of the display device is affected.

Contents of the invention

In order to compensate the influence of the threshold voltage on the current flowing through the organic light-emitting device OLED in the prior art, and then improve the uniformity of the brightness of the display device, the present invention proposes a pixel circuit capable of compensating the threshold voltage to improve the uniformity of the display brightness Its driving method and display device including the pixel circuit.

The invention discloses a pixel circuit, which comprises: a first scanning line; a second scanning line; a data line; a first power line; a second power line; a third power line; a light-emitting element connected to the first power supply line and the second power line; the drive transistor includes a gate, and the drive transistor is connected between the light emitting element and the first power line; the first switch includes a first switch connected to the second scan line control electrode, and the first switch is connected to the data line; the second switch includes a second control electrode connected to the first scan line, and the second switch is connected between the third power line and the gate The third switch includes a third control electrode connected to the first scan line, and the third switch is connected between the first switch and the drive transistor; the fourth switch includes a control electrode connected to the first scan line The fourth control electrode, and the fourth switch is connected between the third power line and the driving transistor; the fifth switch is connected between the first power line and the driving transistor; the first capacitor is connected to the first between a switch and the gate; and a second capacitor connected to the first electrode of the first switch, the first electrode of the third switch, the first power line and the first terminal of the first capacitor.

As an optional solution, in the pixel circuit, the light emitting element includes an anode connected to the fourth switch and the driving transistor, and a cathode connected to the second power line.

As an optional solution, in the pixel circuit, the first electrode of the first switch, the first electrode of the third switch, the first terminal of the first capacitor and the first terminal of the second capacitor are connected to first node.

As an optional solution, in the pixel circuit, the driving transistor further includes a first electrode connected to the third switch and the fifth switch, and a second electrode connected to the light emitting element.

As an optional solution, in the pixel circuit, the second terminal of the first capacitor, an electrode of the second switch and the gate of the driving transistor are connected to the second node.

As an optional solution, in the pixel circuit, the pixel circuit further includes an emission control driving line, wherein the fifth switch includes a fifth control electrode connected to the emission control driving line.

As an optional solution, in the pixel circuit, the first switch, the second switch, the third switch, the fourth switch and the fifth switch are thin film field effect transistors.

The present invention also provides a display device, the display device comprising: a display panel, the display panel includes: a plurality of pixel units, each pixel unit includes the pixel circuit as claimed in claim 1; a scanning drive unit for providing scan signals to the pixel circuit; a data drive unit, used to provide data signals to the pixel circuit; a first power supply, used to apply a first voltage to the first power supply line; a second power supply, used to apply a second voltage to the the second power line; and a third power supply for applying a second voltage to the third power line; wherein, the voltage value of the second voltage is lower than the voltage value of the first voltage.

Preferably, in the above display device, the display device further includes an emission control driving unit, wherein the emission control driving unit provides an emission control signal to the pixel circuit to control the fifth switch on and off.

The present invention further provides a pixel driving method, which is applied to the above-mentioned pixel circuit, and the driving transistor has a threshold voltage, and the driving method includes:

A. Turn on the second switch, the third switch, the fourth switch, the fifth switch, and the drive transistor, and turn off the first switch, so that the first capacitor and the second capacitor respectively store the third The third voltage corresponding to the output of the power line and the first voltage corresponding to the output of the first power line;

B. Turn on the second switch, the third switch, the fourth switch and the drive transistor, turn off the first switch and the fifth switch, so that the first capacitor is discharged until the stored in the first The voltage in the capacitor is the absolute value of the threshold voltage;

C. Turn on the first switch and the driving transistor, turn off the second switch, the third switch, the fourth switch and the fifth switch, and apply the data voltage corresponding to the output of the data line to the first capacitor, making the gate voltage of the driving transistor equal to the difference between the absolute value of the data voltage and the threshold voltage;

D. Turn on the fifth switch and the drive transistor, turn off the first switch, the second switch, the third switch and the fourth switch, and the corresponding output first voltage of the first power line is applied to the drive The transistor maintains the gate voltage of the driving transistor, and drives the light emitting element to emit light by using the first voltage and the gate voltage.

Preferably, in the driving method, the first scan line outputs a first scan signal and a second scan signal correspondingly, wherein the first scan signal and the second scan signal are periodic signals, and the second scan signal The phase of the signal lags behind the first scanning signal, when the first scanning signal is at low level, the first switch is in the conduction state; when the second scanning signal is at low level, the second switch, the third The switch and the fourth switch are in a conducting state.

Preferably, in the above driving method, the pixel circuit further includes an emission control driving line, and the emission control driving line corresponds to an output control signal, wherein the control signal is a periodic signal, and when the control signal is at a low level, the The fifth switch is in a conducting state.

Preferably, the step C in the driving method further includes the second capacitor storing the data voltage.

Furthermore, in the driving method, the step D further includes the second capacitor maintaining the data voltage, and the first capacitor maintaining the threshold voltage stored in the first capacitor in the step B, so that the driving The transistor maintains this gate voltage.

Compared with the prior art, the pixel circuit and its driving method and display device of the present invention can effectively compensate the threshold voltage of the drive transistor, and further eliminate the influence of different threshold voltages on the current flowing through the light-emitting element, thereby improving Uniformity of luminance among pixels to achieve uniformity of luminance of the display device.

Description of drawings

FIG. 1 is a structural diagram of a pixel circuit in a conventional organic light emitting display device;

Fig. 2 is a basic structural block diagram of a display device in an embodiment of the present invention;

3 is a circuit structure diagram of a pixel circuit in an embodiment of the present invention;

FIG. 4 is a driving timing diagram of the pixel circuit in FIG. 3;

5A to 5D are respectively schematic diagrams of current flowing through the pixel circuit in FIG. 4 during periods T1, T2, T3 and T4 in the driving timing diagram corresponding to FIG. 4;

Detailed ways

In order to have a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed descriptions are provided in conjunction with the embodiments.

Please refer to FIG. 2 and FIG. 3 . FIG. 2 is a block diagram of a basic structure of a display device in an embodiment of the present invention, and FIG. 3 is a circuit structure diagram of a pixel circuit in an embodiment of the present invention. In an embodiment of the present invention, the display device 1 mainly includes a scan driving unit 10, a data driving unit 20, an emission control driving unit 30, and a display panel 60, wherein the display panel 60 includes a plurality of pixel units 50, and each pixel Each unit 50 includes a pixel circuit 100 as shown in FIG. 3 . Therefore, when the display device 1 is working, the scan driving unit 10, the data driving unit 20, and the emission control driving unit 30 are respectively used to provide the scanning signal, the data signal and the emission control signal to the pixel unit 50. Further, the scanning driving unit 10 Correspondingly provide scanning signals to the pixel units 50 in each row through a plurality of scanning lines S[1], S[2]...S[N], and the data driving unit 20 through a plurality of data lines D[1], D[2] ]... D[M] corresponds to providing data signals to the pixel units 50 of each column, and the emission control drive unit 30 corresponds to the The pixel units 50 in each row provide emission control signals, wherein M and N are natural numbers greater than 0. In addition, the display device 1 also includes a first power supply 41 for applying the first voltage VDD to the first power supply line 410; a second power supply 42 for applying the second voltage VSS to the second power supply line 420; and a third power supply 43, for applying the second voltage Vref to the third power line 430, wherein, in general, preferably, the voltage value of the second voltage VSS is lower than the voltage value of the first voltage VDD, in some embodiments, The second voltage VSS may be a ground voltage.

Next, further refer to the pixel circuit shown in FIG. 3 , in this embodiment, the pixel circuit 100 includes a first scanning line S[N-1] and a second scanning line S[N], which are respectively used to provide the first scanning line Signal S1 and second scan signal S2; data line D[M] to provide data voltage Vdata (the above data signal corresponds to the data voltage); first power line 410, second power line 420 and third power line 430 , respectively transmit the first voltage VDD, the second voltage VSS and the third voltage Vref output by the first power supply 41, the second power supply 42 and the third power supply 43 to the pixel circuit 100; the emission control line EM[N] is used to provide The control signal EM is sent to the pixel circuit 100 . Furthermore, the pixel circuit 100 also includes:

The light emitting element OLED is connected between the first power line 410 and the second power line 420;

A driving transistor M6, which includes a gate G, a source S, and a drain D, and the driving transistor M6 is connected between the light emitting element OLED and the first power line 410;

A first switch M1, which includes a first control electrode connected to the second scan line S[N], and the first switch M1 is connected to the data line D[M] for selectively receiving a data voltage Vdata;

A second switch M2, which includes a second control electrode connected to the first scan line S[N-1], and the second switch M2 is connected between the third power line and the gate G of the driving transistor M6;

a third switch M3, which includes a third control electrode connected to the first scan line S[N-1], and the third switch M3 is connected between the first switch M1 and the driving transistor M6;

a fourth switch M4, which includes a fourth control electrode connected to the first scan line S[N-1], and the fourth switch M4 is connected between the third power line 430 and the driving transistor M6;

a fifth switch M5, which includes a fifth control electrode connected to the emission control driving line EM[N], and the fifth switch M5 is connected between the first power line 410 and the driving transistor M6;

The first capacitor C1 is connected between the first switch M1 and the gate G of the driving transistor M6; and

The second capacitor C2 is connected to the first switch M1, the third switch M3, the first power line 410 and the first capacitor C1.

Wherein, the light-emitting element in this embodiment is an organic light-emitting diode (OLED) as an example, but not limited thereto, the light-emitting element can also be an inorganic light-emitting diode or other light-emitting devices; and the first switch M1 in this embodiment The second switch M2, the third switch M3, the fourth switch M4 and the fifth switch M5 may preferably be thin film field effect transistors, but not limited thereto, and may also be other electronic devices capable of realizing switching functions.

More specifically, in this embodiment, the light emitting element has an anode and a cathode, the anode is connected to the fourth switch M4 and the drain of the driving transistor M6, and the cathode is connected to the second power line 420, in other words , when both the fifth switch M5 and the driving transistor M6 are turned on, the fifth switch M5, the driving transistor M6 and the light emitting element OLED can form a series path between the first power line 410 and the second power line 420, and in addition , it should be noted that the following equation is generally used for the current flowing through the light-emitting element OELD:

$I_{\mathrm{OLED}}=\frac{1}{2}\mathrm{\β}{(\mathrm{Vgs}-|\mathrm{Vth}\left|\right)}^2$ [Equation 1]

Wherein, I _OLED is the current flowing through the light-emitting element OELD; Vgs is the voltage applied between the source S and the gate G of the driving transistor M6; Vth is the threshold voltage of the driving transistor M6; β is the gain factor of the driving transistor M6. Therefore, it can be seen from the equation 1 that the current flowing through the light-emitting element OLED can be controlled by using the voltage between the source and the gate of the driving transistor M6, so as to change its luminous intensity, and the purpose of setting the fifth switch M5 is to In order to realize the control of the above-mentioned series path, whether to turn on or not to turn on the light emitting element OLED can be controlled by turning on and off the fifth switch M5.

Returning to the pixel circuit 100 shown in FIG. 3 again, in this embodiment, the first switch M1, the third switch M3, one end of the first capacitor C1 and one end of the second capacitor C2 are connected to the first node A, The other end of the first capacitor C1, the second switch M2 and the gate G of the drive transistor M6 are connected to the second node B, wherein the first switch M1 includes two electrodes besides the first control electrode, one of which is connected to The data line D[M] is used to receive the data voltage Vdata, and its other electrode is connected to the first node. Similarly, each of the second switch M2, the third switch M3, the fourth switch M4 and the fifth switch M5 In addition to the control electrode, it also includes two other electrodes. As shown in FIG. Node B; one electrode of the fourth switch M4 is also connected to the third power line 430 for receiving the third voltage Vref, and the other electrode is connected to the drain D of the driving transistor M6; one electrode of the third switch M3 is connected to To the first node A, the other electrode is connected to the source S of the driving transistor M6; and one electrode of the fifth switch M5 is also connected to the source S of the driving transistor M6, and the other electrode is connected to the source S of the second capacitor C2 The other ends are connected to the first power line 410 for receiving the first voltage VDD.

Please refer further to FIG. 4, which is a driving timing diagram of the pixel circuit in FIG. The emission control signal EM output corresponding to the second scanning signal S2 and the emission control line EM[N] is a periodic signal, as shown in FIG. 4 is a schematic diagram of the waveforms of the above three signals within one cycle. Wherein, the phase of the second scan signal S2 lags behind the first scan signal S1. In addition, please refer to FIG. 3 in conjunction with FIG. When the scanning signal S2 is at a low level, the second switch M2, the third switch M3 and the fourth switch M3 are all in a conducting state; similarly, when the emission control signal EM is at a low level, the fifth switch M5 is also in a conducting state. state.

In the working cycle shown in FIG. 4 , the working process of the pixel circuit 100 is generally divided into four stages: initialization stage, compensation stage, writing stage and emission stage. Then, based on the pixel circuit as shown in FIG. 3 , in order to better explain its working principle and its advantages, supplementary explanations are made in conjunction with the following pixel driving method.

For the above four working stages of the pixel circuit 100, the pixel driving method of the present invention includes the following four steps:

A. Turn on the second switch M2, the third switch M3, the fourth switch M4, the fifth switch M5 and the driving transistor M6, and turn off the first switch M1, so that the first capacitor C1 and the second capacitor C2 respectively store the third power The line 430 corresponds to the output of the third voltage Vref and the first power line 410 corresponds to the output of the first voltage VDD;

B. Turn on the second switch M2, the third switch M3, the fourth switch M4 and the drive transistor M6, turn off the first switch M1 and the fifth switch M5, so that the first capacitor C1 is discharged until it is stored in the first capacitor The voltage in C1 is the absolute value of the threshold voltage Vth;

C. Turn on the first switch M1 and the driving transistor M6, turn off the second switch M2, the third switch M3, the fourth switch M4 and the fifth switch M5, and apply the corresponding output data voltage of the data line to the first capacitor C1, so that The gate voltage of the driving transistor M6 is the difference between the data voltage and the absolute value of the threshold voltage Vth;

D. Turn on the fifth switch M5 and the drive transistor M6, turn off the first switch M1, the second switch M2, the third switch M3 and the fourth switch M4, and the first voltage VDD corresponding to the output of the first power line 410 is applied to the drive The transistor M6 maintains the gate voltage of the driving transistor M6, and uses the first voltage VDD and the gate voltage to drive the light emitting element OLED to emit light.

Wherein, please specifically refer to FIG. 5A to FIG. 5D in conjunction with FIG. 4 , which are schematic diagrams of current flowing through the pixel circuit in FIG. 4 during periods T1, T2, T3 and T4 in the driving timing diagram corresponding to FIG. Step A corresponds to the initialization phase of the pixel circuit 100, that is, during the period T1, as shown in FIG. 5A, the first scanning signal S1 and the emission control signal EM are at a low level and the second scanning signal S2 is at a high level. Therefore, The second switch M2, the third switch M3, the fourth switch M4, the fifth switch M5 and the drive transistor M6 are all in the on state, while the first switch M1 is in the off state. At this time, the first voltage VDD and the third The voltage Vref can charge the second capacitor C2 and the first capacitor C1 respectively, so that the potential Va of the first node A is VDD, and the potential Vb of the second node B is Vref, thereby realizing the initialization of the pixel circuit 100. In addition, , since the fourth switch M4, the fifth switch M5 and the driving transistor M6 are all in the conduction state at this time, the current flowing through the fifth switch M5 and the driving transistor M6 will flow through the fourth switch M4 instead of the light-emitting The element OLED, so the light-emitting element OLED does not emit light during the T1 period.

Step B corresponds to the compensation phase of the pixel circuit 100, that is, during the period T2, as shown in FIG. 5B, the first scan signal S1 is at low level and the second scan signal S2 and the emission control signal EM are at high level. The second switch M2, the third switch M3, the fourth switch M4 and the drive transistor M6 are all in the on state, while the first switch M1 and the fifth switch M5 are in the off state. At this time, the third switch M3, the The turn-on of the four switches M4 and the driving transistor M6 forms a discharge path for the first capacitor C1, because the potential Va of the first node A at the end of the T1 period is VDD, and the voltage connected to the fourth switch M4 is the third voltage at this time Vref (preferably, the voltage value of the third voltage Vref is less than the first voltage VDD), so the first capacitor C1 will discharge, and because the second switch M2 is also turned on, the first capacitor C1 is equivalent to a parallel connection In the driving transistor M6, therefore, after the first capacitor C1 is discharged, it will stop discharging until the voltage difference between its two ends is maintained at the threshold voltage |Vt| of the driving transistor M6. Then, when the first capacitor C1 stops discharging, the first The potential Va of a node A is Vref+|Vt|, and the potential Vb of the second node B remains Vref.

Step C corresponds to the writing phase of the pixel circuit 100, that is, during the period T3, as shown in FIG. 5C, the first scanning signal S1 and the emission control signal EM are at high level and the second scanning signal S2 is at low level, therefore , the first switch M1 and the drive transistor M6 are both in the on state, while the second switch M2, the third switch M3, the fourth switch M4 and the fifth switch M5 are in the off state, at this time, the data line D[M ] The corresponding data voltage Vdata is applied to the first node A through the turned-on first switch M1, so that the second capacitor C2 can store the data voltage Vdata, and the first capacitor C1 will maintain the voltage difference between its two ends during the T2 period |Vt|, therefore, at this time, the potential Vb of the second node B becomes Vdata-|Vt|, that is, the gate voltage of the driving transistor M6 is Vdata-|Vt|. It should be noted that, during the period T2 and T3, since the fifth switch M5 is in the off state, the light emitting element OLED will not emit light.

After the data voltage Vdata is written into the first capacitor C1, the pixel circuit 100 enters the fourth working stage, and step D corresponds to the emission stage of the pixel circuit 100, that is, during the period T4, as shown in FIG. 5D , the first scan The signal S1 and the emission control signal EM are at a high level and the second scanning signal S2 is at a low level, therefore, the fifth switch M5 and the driving transistor M6 are all in a conducting state, and the first switch M1, the second switch M2, the second The three switches M3 and the fourth switch M4 are in the OFF state. At this time, the first voltage VDD corresponding to the output of the first power line 410 is applied to the source S of the driving transistor M6. Since one end of the second capacitor C2 Finally, the first voltage VDD is received, so at this time, the potential Va of the first node A connected to the second capacitor C2 will still maintain the above-mentioned data voltage Vdata, and the first capacitor C1 will also continue to maintain the voltage difference between its two ends |Vt |, so that the driving transistor M6 also continues to maintain its gate voltage, that is, the gate voltage corresponds to the potential Vb of the second node B, and its voltage value is equal to Vdata−|Vt|. Therefore, the voltage value between the source S and the gate G of the driving transistor M6 at this time can be calculated by the following equation:

Vgs=VDD-(Vdata-|Vth|) [Equation 2]

Furthermore, when the pixel circuit 100 is in the period T4, the current flowing through the fifth switch M5 and the driving transistor M6 will flow through the light-emitting element OLED, so that the light-emitting element OLED emits light. At this time, Equation 1 and Equation 2 (substituting Vgs from Equation 2 into Equation 1) yields Equation 3 as follows:

$I_{\mathrm{OLED}}=\frac{1}{2}\mathrm{\β}{(\mathrm{Vgs}-|\mathrm{Vth}\left|\right)}^2=\frac{1}{2}\mathrm{\β}{[\mathrm{VDD}-(\mathrm{Vdata}-|\mathrm{Vth}\left|\right)-|\mathrm{Vth}\left|\right]}^2=\frac{1}{2}\mathrm{\β}{(\mathrm{VDD}-\mathrm{Vdata})}^2$ [Equation 3]

In this way, it can be seen from Equation 3 that the current I OLED flowing through the light-emitting element _OLED is only related to the first voltage VDD and the data voltage Vdata, in other words, the threshold voltage |Vt| The compensation eliminates the influence of the threshold voltage on the current flowing through the light-emitting element OLED, thereby improving the uniformity of the brightness of the display device 1 . In addition, with the change of the data voltage Vdata, the light emitting element OLED can be further realized to emit light with different degrees of brightness, so that the display device 1 can display a gray scale image.

In summary, using the pixel circuit and its driving method and display device of the present invention can effectively compensate the threshold voltage of the driving transistor, and further eliminate the influence of different threshold voltages on the current flowing through the light-emitting element, thereby improving the pixel-to-pixel distance. Uniformity of brightness to achieve uniformity of brightness of the display device.

The present invention has been described by the above-mentioned related embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention all belong to the scope of patent protection of the present invention.

Claims (14)

1. A pixel circuit, characterized in that the pixel circuit comprises: first scan line; second scan line; data line; first power cord; second power cord; third power cord; a light emitting element connected between the first power line and the second power line; a driving transistor, including a gate, and the driving transistor is connected between the light emitting element and the first power line; a first switch, including a first control electrode connected to the second scan line, and the first switch is connected to the data line; a second switch, including a second control electrode connected to the first scan line, and the second switch is connected between the third power line and the gate; a third switch, including a third control electrode connected to the first scan line, and the third switch is connected between the first switch and the driving transistor; a fourth switch, including a fourth control electrode connected to the first scan line, and the fourth switch is connected between the third power line and the driving transistor; a fifth switch connected between the first power line and the driving transistor; a first capacitor connected between the first switch and the gate; and The second capacitor is connected to the first electrode of the first switch, the first electrode of the third switch, the first power line and the first end of the first capacitor. 2. The pixel circuit as claimed in claim 1, wherein the light emitting element comprises an anode connected to the fourth switch and the driving transistor and a cathode connected to the second power line. 3. The pixel circuit according to claim 1, wherein the first electrode of the first switch, the first electrode of the third switch, the first terminal of the first capacitor and the first terminal of the second capacitor connected to the first node. 4. The pixel circuit as claimed in claim 1, wherein the driving transistor further comprises a first electrode connected to the third switch and the fifth switch, and a second electrode connected to the light emitting element. 5. The pixel circuit as claimed in claim 1, wherein the second terminal of the first capacitor, an electrode of the second switch and the gate of the driving transistor are connected to a second node. 6. The pixel circuit as claimed in claim 1, further comprising an emission control driving line, wherein the fifth switch comprises a fifth control electrode connected to the emission control driving line. 7. The pixel circuit as claimed in claim 1, wherein the first switch, the second switch, the third switch, the fourth switch and the fifth switch are thin film field effect transistors. 8. A display device, characterized in that the display device comprises: A display panel that includes: A plurality of pixel units, each of which comprises the pixel circuit according to claim 1; a scan driving unit, used to provide a scan signal to the pixel circuit; a data driving unit for providing data signals to the pixel circuit; a first power source, configured to apply a first voltage to the first power line; a second power source for applying a second voltage to the second power line; and a third power source, configured to apply a second voltage to the third power line; Wherein, the voltage value of the second voltage is lower than the voltage value of the first voltage. 9. The display device according to claim 8, characterized in that the display device further comprises an emission control drive unit, wherein the emission control drive unit provides an emission control signal to the pixel circuit to control the fifth switch on and off . 10. A pixel driving method applied to the pixel circuit as claimed in claim 1, wherein the driving transistor has a threshold voltage, and the driving method comprises: A. Turn on the second switch, the third switch, the fourth switch, the fifth switch, and the drive transistor, and turn off the first switch, so that the first capacitor and the second capacitor respectively store the third The third voltage corresponding to the output of the power line and the first voltage corresponding to the output of the first power line; B. Turn on the second switch, the third switch, the fourth switch and the drive transistor, turn off the first switch and the fifth switch, so that the first capacitor is discharged to discharge, so that the stored in the first The voltage in a capacitor is the absolute value of the threshold voltage; C. Turn on the first switch and the driving transistor, turn off the second switch, the third switch, the fourth switch and the fifth switch, and apply the data voltage corresponding to the output of the data line to the first capacitor, making the gate voltage of the driving transistor equal to the difference between the absolute value of the data voltage and the threshold voltage; D. Turn on the fifth switch and the drive transistor, turn off the first switch, the second switch, the third switch and the fourth switch, and the corresponding output first voltage of the first power line is applied to the drive The transistor maintains the gate voltage of the drive transistor, and drives the light emitting element to emit light by using the first voltage and the gate voltage. 11. The driving method according to claim 10, wherein the first scanning line correspondingly outputs a first scanning signal and a second scanning signal, wherein the first scanning signal and the second scanning signal are periodic signals, And the phase of the second scanning signal lags behind the first scanning signal, when the first scanning signal is at low level, the first switch is in the conduction state; when the second scanning signal is at low level, the second The switch, the third switch and the fourth switch are in a conducting state. 12. The driving method according to claim 10, characterized in that the pixel circuit further comprises an emission control driving line corresponding to an output control signal, wherein the control signal is a periodic signal, and when the control signal is in When the level is low, the fifth switch is in a conduction state. 13. The driving method as claimed in claim 10, wherein the step C further comprises the second capacitor storing the data voltage. 14. The driving method as claimed in claim 13, wherein the step D further comprises the second capacitor maintaining the data voltage, the first capacitor maintaining the threshold voltage stored in the first capacitor in the step B, In turn, the driving transistor maintains the gate voltage.