Pixel driving circuit, driving method and display panel

Abstract

The application discloses a pixel driving circuit, a driving method and a display panel, wherein the pixel driving circuit adopts 8T2C, and comprises a driving transistor, a writing subcircuit, a first storage capacitor, a light-emitting control subcircuit, a first threshold value compensation subcircuit, a second storage capacitor, a second threshold value compensation subcircuit, a light-emitting control subcircuit, a first initialization subcircuit, a second initialization subcircuit and a light-emitting element; the first threshold value compensation subcircuit is connected with the first storage capacitor and the second storage capacitor; and the second threshold value compensation subcircuit is connected with the control end of the driving transistor and the driving transistor. The pixel driving circuit provided by the application prolongs the writing time of the data voltage by adjusting the writing mode of the data signal, guarantees the writing precision, and can improve the refresh rate of the panel. By adjusting the compensation mode of the threshold voltage of the driving transistor, the influence of the voltage drop of the power supply voltage end on the display uniformity is eliminated, and the pixel driving is suitable for large-size display panels.

Description

TECHNICAL FIELD

[0001] The present application generally relates to the technical field of display, and in particular to a pixel driving circuit, a driving method and a display panel. BACKGROUND

[0002] In recent years, thanks to the excellent display effect of the active matrix organic light emitting diode (AMOLED) display, the AMOLED industry has developed rapidly at home and abroad.

[0003] In the process of displaying the flexible AMOLED product, multiple thin film transistors (TFTs) and capacitors are needed to work together to solve the problem of non-uniform threshold voltage of TFT. However, with the continuous development of the display industry, low cost, low power consumption, large size and high refresh rate have gradually become the competitive direction of display panels.

[0004] However, in the prior art, as the display panel increases, the power supply end V DD The lengthening of the wire leads to the voltage drop of V DD The voltage drop of the wire is increased, which in turn leads to non-uniform display brightness. In addition, when the refresh rate of the display panel is increased, the signal voltage may not be fully written, which may lead to display abnormalities. SUMMARY

[0005] In view of the above defects or deficiencies in the prior art, it is desirable to provide a pixel driving circuit, a driving method and a display panel, which can realize low cost, low power consumption, large size and high refresh rate of the display panel.

[0006] In a first aspect, the present application provides a pixel driving circuit, comprising: a driving transistor, a write-in sub-circuit, a first storage capacitor, a light-emitting control sub-circuit, a first threshold compensation sub-circuit, a second storage capacitor, a second threshold compensation sub-circuit, a first initialization sub-circuit, a second initialization sub-circuit, and a light-emitting element, wherein

[0007] The driving transistor is configured to control the driving current of the light-emitting element;

[0008] The first end of the first storage capacitor is electrically connected to a first power supply voltage end;

[0009] The write-in sub-circuit is configured to provide a signal of a data signal input end to the second end of the first storage capacitor under the control of a first scanning signal;

[0010] The first threshold compensation sub-circuit is connected with the second end of the first storage capacitor and the first end of the second storage capacitor, and is used for turning on or turning off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light-emitting control signal.

[0011] The second end of the second storage capacitor is connected with the control end of the driving transistor, and is used for voltage compensation of the driving transistor.

[0012] The second threshold compensation sub-circuit is electrically connected with the control end of the driving transistor and the second end of the driving transistor, and is used for voltage compensation of the control end of the driving transistor under the control of a second scan signal.

[0013] The light-emitting control sub-circuit is electrically connected with the second end of the driving transistor and the light-emitting element, and is used for applying a current of the driving transistor to the light-emitting element under the control of the light-emitting control signal.

[0014] The first initialization sub-circuit is connected with the first end of the second storage capacitor, and is used for resetting the first end of the second storage capacitor under the control of the first scan signal.

[0015] The second initialization sub-circuit is connected with the first end of the light-emitting element and the second end of the second storage capacitor, and is used for applying a signal of a reset voltage end to the first end of the light-emitting element and the second end of the second storage capacitor under the control of a reset signal, and the second end of the light-emitting element is electrically connected with a second power voltage end.

[0016] Optionally, the second initialization sub-circuit comprises a first transistor and a second transistor, the control end of the first transistor is connected with the reset signal, the first end of the first transistor is connected with the reset voltage end, and the second end of the first transistor is connected with the control end of the driving transistor and the second end of the second transistor storage capacitor; the control end of the second transistor is connected with the reset signal, the first end of the second transistor is connected with the reset voltage end, and the second end of the second transistor is connected with the first end of the light-emitting element.

[0017] Optionally, the write-in sub-circuit comprises a fourth transistor, the control end of the fourth transistor is electrically connected with the first scan signal, the first end of the fourth transistor is connected with the data signal input end, and the second end of the fourth transistor is connected with the second end of the first capacitor.

[0018] Optionally, the first threshold voltage compensation sub-circuit comprises a fifth transistor, a control terminal of the fifth transistor is connected with the light-emitting control signal, a first terminal of the fifth transistor is connected with the second terminal of the fourth transistor and the second terminal of the first storage capacitor, and a second terminal of the fifth transistor is connected with the first terminal of the second storage capacitor.

[0019] Optionally, the second initialization sub-circuit comprises a sixth transistor, a control terminal of the sixth transistor is connected with the first scan signal, a first terminal of the sixth transistor is connected with the second terminal of the fifth transistor and the first terminal of the second storage capacitor, and a second terminal of the sixth transistor is grounded.

[0020] Optionally, the second threshold voltage compensation sub-circuit comprises a seventh transistor, a control terminal of the seventh transistor is connected with the second scan signal, a first terminal of the seventh transistor is connected with the second terminal of the driving transistor, and a second terminal of the seventh transistor is connected with the control terminal of the driving transistor.

[0021] Optionally, the light-emitting control sub-circuit comprises an eighth transistor, a control terminal of the eighth transistor is connected with the light-emitting control signal, a first terminal of the eighth transistor is connected with the second terminal of the driving transistor, and a second terminal of the eighth transistor is connected with the first terminal of the light-emitting element.

[0022] Optionally, the fourth transistor and the sixth transistor are oxide P-type transistors, and the first transistor, the second transistor, the driving transistor, the fifth transistor, the seventh transistor and the eighth transistor are low-temperature polysilicon N-type transistors.

[0023] In a second aspect, the present application provides a driving method of a pixel driving circuit, the driving method comprising a first stage, a second stage and a third stage.

[0024] In the first stage, the write sub-circuit writes the data voltage of the data signal input terminal to the storage capacitor in response to the first scan signal; the first initialization sub-circuit resets the first terminal of the first storage capacitor in response to the first scan signal; and the second initialization sub-circuit applies the reset voltage of the initialization signal input terminal to the control terminal of the driving transistor and the first terminal of the light-emitting element in response to the reset signal.

[0025] In the second stage, the writing sub-circuit continues to write the data voltage of the data signal input end to the first storage capacitor in response to a first scan signal; the first initialization sub-circuit continues to reset the first end of the second storage capacitor in response to the first scan signal; the second threshold compensation sub-circuit turns on the second end and the control end of the driving transistor in response to a second scan signal, and the first power voltage end performs voltage compensation on the control end of the driving transistor through the second end of the driving transistor until the driving transistor is turned on;

[0026] In the third stage, the first threshold compensation sub-circuit turns on the first storage capacitor and the second storage capacitor and writes the voltage of the first storage capacitor to the second storage capacitor in response to a light-emitting signal; the second storage capacitor performs voltage compensation on the control end of the driving transistor; and the light-emitting control sub-circuit applies the driving current of the driving transistor to the light-emitting element in response to the light-emitting signal.

[0027] In a third aspect, the present application provides a display panel comprising the pixel driving circuit as any of the above.

[0028] The technical scheme provided by the embodiments of the present application can include the following beneficial effects:

[0029] The pixel driving circuit provided by the embodiments of the present application prolongs the writing time of the data voltage by adjusting the writing mode of the data signal, guarantees the writing precision, and can improve the refresh rate of the panel. By adjusting the compensation mode of the threshold voltage of the driving transistor, the influence of the voltage drop of the power voltage end due to the wiring on the display uniformity is eliminated, and the pixel driving is suitable for large-size display panels. BRIEF DESCRIPTION OF DRAWINGS

[0030] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0031] Figure 1 A structural schematic diagram of a pixel driving circuit provided by the embodiments of the present application;

[0032] Figure 2 A driving timing diagram of a pixel driving circuit provided by the embodiments of the present application;

[0033] Figure 3 A current direction schematic diagram corresponding to the first stage of a pixel driving circuit provided by the embodiments of the present application;

[0034] Figure 4 A current direction schematic diagram corresponding to the second stage of a pixel driving circuit provided by the embodiments of the present application;

[0035] Figure 5A pixel driving circuit provided for an embodiment of the present application corresponds to a schematic diagram of a current direction of the third stage; DETAILED DESCRIPTION

[0036] The present application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that, for the sake of description, only the parts related to the application are shown in the drawings.

[0037] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0038] AMOLED can emit light by thin film transistor (TFT) in the saturation state to generate driving current and drive organic light emitting diode (OLED) to emit light. The brightness of OLED is proportional to the size of the driving current provided to the OLED device. Therefore, in order to achieve the best display effect, a larger driving current is required. Since low-temperature polysilicon can provide higher electron mobility, low-temperature polysilicon is more commonly used to make TFT in AMOLED display technology.

[0039] In recent years, with the gradual maturity of oxide semiconductor preparation process, because it does not need to be crystallized, the preparation process is simple, and it has a lower off-state current, oxide TFT is gradually applied to display panels, but its electron mobility is relatively low compared to LTPS, which is not suitable for independent application.

[0040] The technical solution of the present application combines two kinds of TFTs using LTPO technology, retains the high mobility of LTPS, and also introduces the low leakage characteristics of oxide semiconductor, becoming a new type of display technology. Oxide semiconductors used for display are mostly N-type semiconductors. By taking advantage of the opposite threshold voltages of oxide TFT and LTPS TFT, an appropriate driving circuit structure can be used to make oxide TFT and LTPS TFT share a gate line, reducing system power consumption.

[0041] Please see Figure 1 The present application provides a pixel driving circuit, comprising: a driving transistor DN, a write sub-circuit 1, a first storage capacitor C1, a light-emitting control sub-circuit 2, a first threshold compensation sub-circuit 3, a second storage capacitor C2, a second threshold compensation sub-circuit 4, a first initialization sub-circuit 5, a second initialization sub-circuit 6, and a light-emitting element 7, wherein

[0042] The driving transistor DN is used to control the driving current of the light-emitting element.

[0043] The first end of the first storage capacitor C1 is electrically connected with a first power voltage terminal.

[0044] The write sub-circuit 1 is used for providing a signal of a data signal input terminal to the second end of the first storage capacitor C1 under the control of a first scan signal Gate1.

[0045] The first threshold compensation sub-circuit 3 is connected with the second end of the first storage capacitor C1 and the first end of the second storage capacitor C2, and is used for turning on or off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light-emitting control signal; under the control of the light-emitting control signal, the first end of the second storage capacitor and the second end of the first storage capacitor are turned on, and the voltage of the second end of the first storage capacitor is written to the first end of the second storage capacitor.

[0046] The second end of the second storage capacitor C2 is connected with the control terminal of the driving transistor DN, and is used for voltage compensation of the driving transistor DN; when the second end of the second storage capacitor has a voltage, the voltage of the second end can be directly applied to the control terminal of the driving transistor, for voltage compensation of the driving transistor.

[0047] The second threshold compensation sub-circuit 4 is electrically connected with the control terminal of the driving transistor DN and the second end of the driving transistor DN, and is used for voltage compensation of the control terminal of the driving transistor DN under the control of a second scan signal Gate2; under the control of the second scan signal, the second threshold compensation sub-circuit can turn on the second end and the control terminal of the driving transistor, and apply the voltage of the second end to the control terminal.

[0048] The light-emitting control sub-circuit 2 is electrically connected with the second end of the driving transistor DN and the light-emitting element 7, and is used for applying the current of the driving transistor DN to the light-emitting element 7 under the control of the light-emitting control signal EM.

[0049] The first initialization sub-circuit 5 is connected with the first end of the second storage capacitor C2, and is used for resetting the first end of the second storage capacitor C2 under the control of the first scan signal Gate1.

[0050] The second initialization sub-circuit 6 is connected with the first end of the light-emitting element 7 and the second end of the second storage capacitor C2, and is used for applying a signal of a reset voltage terminal to the first end of the light-emitting element 7 and the second end of the second storage capacitor C2 under the control of a reset signal Rest, and the second end of the light-emitting element 7 is electrically connected with a second power voltage terminal.

[0051] It should be noted that the light emitting element 7 can be a current driven light emitting device including an LED (Light Emitting Diode) or an OLED (Organic Light Emitting Diode) in the prior art, and the following embodiments are described by taking the OLED as an example. It should be noted that the light emitting element 7 can be various types of OLEDs, such as top emission, bottom emission, double-sided emission, etc., and can emit red light, green light, blue light, or white light, etc., and the embodiments of the present application do not limit this.

[0052] The "control end" specifically refers to the gate of the transistor, the "first end" specifically refers to the source of the transistor, and the "second end" specifically refers to the drain of the transistor. Of course, it should be known by those skilled in the art that the "first end" and the "second end" can be interchanged, i.e., the "first end" specifically refers to the drain of the transistor, and the "second end" specifically refers to the source of the transistor.

[0053] The first power supply voltage end V DD For example, maintain the input DC high level signal, and the DC high level is called the first voltage; the second power supply voltage end V SS For example, maintain the input DC low level signal, and the DC low level is called the second voltage, which is lower than the first voltage. The following embodiments are the same, and will not be described again.

[0054] In addition, according to the different characteristics of the transistor semiconductor, the transistor can be divided into N-type transistor and P-type transistor. Among them, when the transistor is used as a switching transistor, the N-type switching transistor is turned on under the control of the high level switching control signal and is turned off under the control of the low level switching control signal; the P-type switching transistor is turned on under the control of the low level switching control signal and is turned off under the control of the high level switching control signal.

[0055] It should be noted that the size of the voltage compensation value of the second storage capacitor to the control end of the driving transistor and the voltage compensation value of the second threshold compensation sub-circuit to the control end of the driving transistor in the embodiments of the present application is not specifically limited, and the mechanisms of the voltage compensation of the two are different. The voltage compensation of the second storage capacitor to the driving transistor is based on the principle of capacitor bootstrap, and the voltage of the second storage capacitor is written to the control end of the driving transistor, and the second threshold compensation sub-circuit compensates the voltage of the control end through the second end of the driving transistor.

[0056] The two compensation methods are specifically described below in combination with specific implementation cases.

[0057] The second initialization sub-circuit 6 comprises a first transistor T1 and a second transistor T2, the control end of the first transistor T1 is connected with the reset signal Rest, the first end of the first transistor T1 is connected with the reset voltage end, and the second end of the first transistor T1 is connected with the control end of the driving transistor DN and the second end of the storage capacitor of the second transistor T2; the control end of the second transistor T2 is connected with the reset signal Rest, the first end of the second transistor T2 is connected with the reset voltage end, and the second end of the second transistor T2 is connected with the first end of the light-emitting element 7.

[0058] The writing sub-circuit 1 comprises a fourth transistor T4, the control end of the fourth transistor T4 is electrically connected with the first scanning signal Gate1, the first end of the fourth transistor T4 is connected with the data signal input end, and the second end of the fourth transistor T4 is connected with the second end of the first capacitor.

[0059] The first threshold compensation sub-circuit 3 comprises a fifth transistor T5, the control end of the fifth transistor T5 is connected with the light-emitting control signal EM, the first end of the fifth transistor T5 is connected with the second end of the fourth transistor T4 and the second end of the first storage capacitor C1, and the second end of the fifth transistor T5 is connected with the first end of the second storage capacitor C2.

[0060] The second initialization sub-circuit 6 comprises a sixth transistor T6, the control end of the sixth transistor T6 is connected with the first scanning signal Gate1, the first end of the sixth transistor T6 is connected with the second end of the fifth transistor T5 and the first end of the second storage capacitor C2, and the second end of the sixth transistor T6 is grounded.

[0061] The second threshold compensation sub-circuit 4 comprises a seventh transistor T7, the control end of the seventh transistor T7 is connected with the second scanning signal Gate2, the first end of the seventh transistor T7 is connected with the second end of the driving transistor DN, and the second end of the seventh transistor T7 is connected with the control end of the driving transistor DN.

[0062] The light-emitting control sub-circuit 2 comprises an eighth transistor T8, the control end of the eighth transistor T8 is connected with the light-emitting control signal EM, the first end of the eighth transistor T8 is connected with the second end of the driving transistor DN, and the second end of the eighth transistor T8 is connected with the first end of the light-emitting element 7.

[0063] The fourth transistor T4 and the sixth transistor T6 are oxide P-type transistors, and the first transistor T1, the second transistor T2, the driving transistor DN, the fifth transistor T5, the seventh transistor T7 and the eighth transistor T8 are low temperature poly silicon N-type transistors.

[0064] The low temperature poly silicon thin film transistor (LTPS) adopts poly silicon deposition to form an active layer. The LTPS has high electron mobility, fast reaction speed, and advantages of high brightness, high resolution and low power consumption.

[0065] The oxide thin film transistor (oxide TFT) adopts an oxide semiconductor as an active layer of the TFT, such as indium gallium zinc oxide (IGZO). The oxide semiconductor has high electron mobility and good off characteristics, and is simple in process and has high compatibility with amorphous silicon process compared with the LTPS.

[0066] Of course, the oxide thin film transistor can also be other metal oxide semiconductors, such as indium zinc tin oxide (IZTO) or indium gallium zinc tin oxide (IGZTO). The oxide thin film transistor can effectively reduce the size of the transistor and prevent leakage current, so that the pixel circuit can be applied to low frequency driving, and the resolution of the display panel can be increased.

[0067] In order to reduce the power consumption of the OLED, a low frequency signal can be used to drive the pixel circuit. However, when the pixel circuit is implemented by using P-type transistors, the leakage current of the P-type transistor is relatively large, and low frequency driving can cause flicker and other phenomena, thereby limiting the use of the pixel circuit. In the embodiment of the present application, the pixel circuit is a hybrid N-type and P-type transistor pixel circuit, which can overcome the flicker phenomenon when the pixel circuit is used for low frequency driving. At the same time, since the leakage current of the N-type transistor is small, the aging problem of the N-type transistor does not need to be considered.

[0068] The fourth transistor T4, the first storage capacitor C1 and the fifth transistor T5 are connected at the first node N1, the fifth transistor T5, the sixth transistor T6 and the second storage capacitor C2 are connected at the second node N2, and the second storage capacitor C2, the driving transistor DN, the first transistor T1 and the second transistor T2 are connected at the third node N3.

[0069] It should be noted that in the description of the embodiments of the present disclosure, the first node N1, the second node N2 and the third node N3 do not represent actual components, but represent the convergence points of the relevant circuit connections in the circuit diagram.

[0070] The fourth transistor T4 and the sixth transistor T6 are PMOS, which are turned on when the first scan signal Gate1 is low and turned off when the first scan signal Gate1 is high; the first transistor T1 and the second transistor T2 are NMOS, which are turned on when the reset signal Rest is high and turned off when the reset signal Rest is low; the fifth transistor T5 and the eighth transistor T8 are NMOS, which are turned on when the emission control signal EM is high and turned off when the emission control signal EM is low; and the seventh transistor T7 is NMOS, which is turned on when the second scan signal Gate2 is high and turned off when the second scan signal Gate2 is low.

[0071] The present application also provides a driving method of the pixel driving circuit, which comprises a first stage T1, a second stage T2 and a third stage T3. The first stage T1, the second stage T2 and the third stage T3 are stages occurring in sequence, and the corresponding input timing is as shown in Figure 2 .

[0072] In the first stage T1, the write-in sub-circuit 1 writes the data voltage at the data signal input end into the storage capacitor in response to the first scan signal Gate1; the first initialization sub-circuit 5 resets the first end of the first storage capacitor C1 in response to the first scan signal Gate1; and the second initialization sub-circuit 6 applies the reset voltage at the initialization signal input end to the control end of the driving transistor DN and the first end of the light-emitting element 7 in response to the reset signal Rest.

[0073] Specifically, Rest = 0, Gate1 = 1, Gate2 = 1, EM = 1, the first transistor T1, the second transistor T2, the fourth transistor T4 and the sixth transistor T6 are turned on, and the fifth transistor T5, the seventh transistor T7 and the eighth transistor T8 are turned off. As shown in Figure 3 .

[0074] The fourth transistor T4 in the write-in sub-circuit 1 is turned on, and the voltage V data at the data signal input end is written into the first node N1, at which time the voltage of the first node N1 is V data .

[0075] The sixth transistor T6 in the first initialization sub-circuit is turned on, and the voltage of the second node N2 is initialized, at which time the voltage of the second node N2 is 0.

[0076] The first transistor T1 in the second initialization sub-circuit is turned on, and the reset voltage V init at the initialization signal input end is transmitted to the third node N3, at which time the voltage of the third node N3 is Vinit ; the second transistor T2 is turned on, and the reset voltage V init is transmitted to the anode of the light emitting element 7, so that the positive charge of the anode is released.

[0077] It should be noted that in the first stage T1, the reset and data writing are implemented in the embodiments of the present application. In this stage, the driving transistor DN is turned on, but no current flows in the driving transistor DN because the eighth transistor T8 and the seventh transistor T7 are both turned off.

[0078] In the second stage T2, the write sub-circuit 1 continues to write the data voltage of the data signal input end into the first storage capacitor C1 in response to the first scan signal Gate1; the first initialization sub-circuit 5 continues to reset the first end of the second storage capacitor C2 in response to the first scan signal Gate1; the second threshold compensation sub-circuit 4 turns on the second end and the control end of the driving transistor DN in response to the second scan signal Gate2, and the first power voltage end performs voltage compensation on the control end of the driving transistor DN through the second end of the driving transistor DN until the driving transistor DN is turned on.

[0079] Specifically, Rest = 1, Gate1 = 1, Gate2 = 0, EM = 1, the fourth transistor T4, the sixth transistor T6, and the seventh transistor T7 are turned on, and the first transistor T1, the second transistor T2, the fifth transistor T5, and the eighth transistor T8 are turned off. In the embodiments of the present application, the data writing and voltage compensation are implemented in the second stage T2. As Figure 4 shown.

[0080] The fourth transistor T4 in the write sub-circuit 1 is turned on, and the voltage V data of the data signal input end is written into the first node N1, and at this time, the voltage of the first node N1 is V data .

[0081] The sixth transistor T6 in the first initialization sub-circuit is turned on, and the voltage of the second node N2 is initialized, and at this time, the voltage of the second node N2 is 0.

[0082] The seventh transistor T7 in the second threshold compensation sub-circuit 4 is turned on, and the second end and the control end of the driving transistor DN are turned on, and the voltage V DD of the first end of the driving transistor DN is compensated on the third node N3 through the second end of the driving transistor DN until the voltage of the third node N3 reaches V DD + V th , and the driving transistor DN is turned off, the voltage compensation of the driving transistor DN is implemented. Vth is the threshold voltage corresponding to the driving transistor DN.

[0083] In the third stage T3, the first threshold voltage compensation sub-circuit 3 turns on the first storage capacitor C1 and the second storage capacitor C2 in response to the light emitting signal and writes the voltage of the first storage capacitor C1 into the second storage capacitor C2; the second storage capacitor C2 performs voltage compensation on the control end of the driving transistor DN; the light emitting control sub-circuit 2 applies the driving current of the driving transistor DN to the light emitting element 7 in response to the light emitting signal.

[0084] Specifically, Rest = 1, Gate1 = 0, Gate2 = 1, EM = 0, the fifth transistor T5 and the eighth transistor T8 are turned on, and the first transistor T1, the second transistor T2, the fourth transistor T4, the sixth transistor T6 and the seventh transistor T7 are turned off. In the embodiment of the application, light emission and voltage compensation are realized in the third stage T3. As shown in the figure. Figure 5

[0085] The fifth transistor T5 in the first threshold voltage compensation sub-circuit 3 is turned on to transmit the voltage Vdata of the first node N1 to the second node N2, and the voltage of the second node N2 is Vdata. data The third node N3 is self-boosted to Vdata+VDD according to the voltage of the capacitor in the second stage T2, and the voltage of the first end of the driving transistor DN is Vdata+VDD+VDD. data DD th data DD The driving transistor DN is turned on.

[0086] The eighth transistor T8 in the light emitting control sub-circuit 2 is turned on to apply the driving current of the driving transistor DN to the light emitting element 7 to drive the light emitting element 7 to emit light.

[0087] It should be noted that the capacitor self-boosting mainly applies the characteristics of the capacitor, that is, the voltage across the capacitor cannot be suddenly changed, and there is always a charging and discharging process to generate the voltage self-boosting and potential self-boosting effect. The voltage across refers to the voltage of one side of the capacitor relative to the other side. When the voltage of the negative end of the capacitor is increased, the voltage of the positive end remains the original voltage difference of the negative end, that is, the voltage of the positive end is lifted by the negative end.

[0088] The voltage Vdata of the first node N1 is transmitted to the second node N2 through the turned-on fifth transistor T5, and the voltage of the second node N2 becomes Vdata. data The third node N3 is self-boosted to Vdata+VDD according to the voltage of the capacitor in the second stage T2, and the voltage of the first end of the driving transistor DN is Vdata+VDD+VDD. DD th DD th data Therefore, in this stage, the driving transistor DN also remains turned on. ​​​​​​​​​

[0089] The voltage at each stage node is shown in the following table.

[0090] First stage T1 Second stage T2 Third stage T3 N1 V data ]]> V data ]]> V data ]]> N2 0 0 V data ]]> N3 V init ]]> V DD +V th ]]> V DD +V th +V data ]]>

[0091] In the third stage T3, the driving transistor DN works in saturation state, according to the saturation state current characteristic, the saturation current I flowing through the driving transistor DN and used for driving the light emitting element 7 to emit light satisfies the formula:

[0092] I = 1 / 2 * mu * Cox * W / L * (Vgs-V th ) 2

[0093] = K (V DD + V th + V data -V DD -V th ) 2

[0094] = K (V data ) 2 .

[0095] Wherein K is a structure parameter, the value of which is relatively stable in the same structure and can be regarded as a constant. Thus, it can be seen that the working current of the light emitting element 7 is not affected by the threshold voltage V th of the driving transistor DN, and the threshold voltage V th of the driving transistor DN caused by process and long-time operation is completely solved, thereby improving the display uniformity.

[0096] In the embodiment of the present application, since the working current of the light emitting element 7 is not affected by the size of V DD , in the embodiment of the present application, V DD can be pulled down while keeping the pressure difference between V SS and V DD unchanged, such as changing V DD from 4.6V to 3V and changing V SS from -2.4V to -4V, thereby reducing the amount of capacitor charging and shortening the charging time.

[0097] The present application reduces the leakage current at the key position by introducing the oxide TFT, and also reduces one gate line, thereby reducing the power consumption of the display panel. By adjusting the compensation mode of the threshold voltage of the driving transistor DN, the influence of the V DD pressure drop on the display uniformity is eliminated, which is suitable for pixel driving of large-size display panels. By adjusting the writing mode of V data , the writing time of the data voltage is prolonged, the writing precision is ensured, and the refresh rate of the panel can be improved.

[0098] In addition, the application provides a display panel comprising the pixel driving circuit as described in any of the above.

[0099] The display panel can be applied to an OLED display device, an AMOLED display device, a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator, or any product or component having a display function.

[0100] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0101] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0102] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The terms appearing in this document, such as "provided" and the like, can mean that one component is directly attached to another component, or that one component is attached to another component through an intermediate component. The features described in one embodiment herein can be applied to another embodiment alone or in combination with other features, unless the features are not applicable in the other embodiment or are otherwise stated.

[0103] The present application has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and illustration, and are not intended to limit the present application to the described embodiments. Those skilled in the art can understand that more variations and modifications can be made according to the teachings of the present application, and these variations and modifications all fall within the scope of the present application.

Claims

1. A driving method of a pixel driving circuit, characterized by, The pixel driving circuit comprises a driving transistor, a writing sub-circuit, a first storage capacitor, a light-emitting control sub-circuit, a first threshold value compensation sub-circuit, a second storage capacitor, a second threshold value compensation sub-circuit, a first initialization sub-circuit, a second initialization sub-circuit and a light-emitting element, wherein The driving transistor is used for controlling the driving current of the light-emitting element; The first end of the first storage capacitor is electrically connected with a first power supply voltage end; The writing sub-circuit is used for providing the signal of a data signal input end to the second end of the first storage capacitor under the control of a first scanning signal; The first threshold value compensation sub-circuit is connected with the second end of the first storage capacitor and the first end of the second storage capacitor, and is used for turning on or off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light-emitting control signal; The second end of the second storage capacitor is connected with the control end of the driving transistor, and is used for voltage compensation of the driving transistor; The second threshold value compensation sub-circuit is electrically connected with the control end of the driving transistor and the second end of the driving transistor, and is used for voltage compensation of the control end of the driving transistor under the control of a second scanning signal; The light-emitting control sub-circuit is electrically connected with the second end of the driving transistor and the light-emitting element, and is used for applying the current of the driving transistor to the light-emitting element under the control of the light-emitting control signal; The first initialization sub-circuit is connected with the first end of the second storage capacitor, and is used for resetting the first end of the second storage capacitor under the control of the first scanning signal; The second initialization sub-circuit is connected with the first end of the light-emitting element and the second end of the second storage capacitor, and is used for applying the signal of a reset voltage end to the first end of the light-emitting element and the second end of the second storage capacitor under the control of a reset signal, and the second end of the light-emitting element is electrically connected with a second power supply voltage end; The driving method comprises a first stage, a second stage and a third stage: In the first stage, the writing sub-circuit writes the data voltage of the data signal input end to the storage capacitor in response to the first scanning signal; the first initialization sub-circuit resets the first end of the first storage capacitor in response to the first scanning signal; and the second initialization sub-circuit applies the reset voltage of the initialization signal input end to the control end of the driving transistor and the first end of the light-emitting element in response to the reset signal; In the second stage, the writing sub-circuit continues to write the data voltage of the data signal input end to the first storage capacitor in response to the first scanning signal; the first initialization sub-circuit continues to reset the first end of the second storage capacitor in response to the first scanning signal; the second threshold value compensation sub-circuit turns on the second end and the control end of the driving transistor in response to the second scanning signal, and the first power supply voltage end performs voltage compensation on the control end of the driving transistor through the second end of the driving transistor until the driving transistor is turned on; In the third stage, the first threshold compensation sub-circuit turns on the first storage capacitor and the second storage capacitor in response to the light emitting signal and writes the voltage of the first storage capacitor into the second storage capacitor; the second storage capacitor performs voltage compensation on the control end of the driving transistor; the light emitting control sub-circuit applies the driving current of the driving transistor to the light emitting element in response to the light emitting signal.

2. The driving method of the pixel driving circuit according to claim 1, wherein The second initialization sub-circuit comprises a first transistor and a second transistor, the control end of the first transistor is connected with the reset signal, the first end of the first transistor is connected with the reset voltage end, and the second end of the first transistor is connected with the control end of the driving transistor and the second end of the second transistor storage capacitor; the control end of the second transistor is connected with the reset signal, the first end of the second transistor is connected with the reset voltage end, and the second end of the second transistor is connected with the first end of the light emitting element.

3. The driving method of the pixel driving circuit according to claim 2, wherein The write sub-circuit comprises a fourth transistor, the control end of the fourth transistor is electrically connected with the first scan signal, the first end of the fourth transistor is connected with the data signal input end, and the second end of the fourth transistor is connected with the second end of the first storage capacitor.

4. The driving method of the pixel driving circuit according to claim 3, wherein The first threshold compensation sub-circuit comprises a fifth transistor, the control end of the fifth transistor is connected with the light emitting control signal, the first end of the fifth transistor is connected with the second end of the fourth transistor and the second end of the first storage capacitor, and the second end of the fifth transistor is connected with the first end of the second storage capacitor.

5. The driving method of the pixel driving circuit according to claim 4, wherein The second initialization sub-circuit comprises a sixth transistor, the control end of the sixth transistor is connected with the first scan signal, the first end of the sixth transistor is connected with the second end of the fifth transistor and the first end of the second storage capacitor, and the second end of the sixth transistor is grounded.

6. The driving method of the pixel driving circuit according to claim 5, wherein The second threshold compensation sub-circuit comprises a seventh transistor, the control end of the seventh transistor is connected with the second scan signal, the first end of the seventh transistor is connected with the second end of the driving transistor, and the second end of the seventh transistor is connected with the control end of the driving transistor.

7. The driving method of the pixel driving circuit according to claim 6, wherein The light emitting control sub-circuit comprises an eighth transistor, the control end of the eighth transistor is connected with the light emitting control signal, the first end of the eighth transistor is connected with the second end of the driving transistor, and the second end of the eighth transistor is connected with the first end of the light emitting element. 8.The driving method of the pixel driving circuit according to claim 7, characterized in that, The fourth transistor and the sixth transistor are oxide P-type transistors, and the first transistor, the second transistor, the driving transistor, the fifth transistor, the seventh transistor and the eighth transistor are low-temperature polysilicon N-type transistors.

Images