A pixel circuit, a driving method and a display device

Abstract

The application provides a pixel circuit, a driving method and a display device. The pixel circuit comprises a pulse amplitude modulation module, a light emitting element and a pulse width modulation module. The pulse amplitude modulation module comprises a first driving switch module, a first reset module, a first storage capacitor, a first compensation module and an amplitude modulation driving module. The first driving switch module receives a second reference voltage sent by the first reset module through a second end and is connected with the light emitting element. A control end of the first driving switch module receives a third reference voltage before a light emitting stage, and a difference between the third reference voltage and the second reference voltage is greater than a first threshold voltage. The first storage capacitor and the first compensation module are sequentially arranged between the second end and the control end of the first driving switch module. The amplitude modulation driving module provides an amplitude modulation data voltage to the first storage capacitor. The pulse width modulation module controls a voltage of the control end of the first driving switch module in the light emitting stage. The application can be used for threshold compensation, reduces power consumption and improves display quality.

Description

Technical Field

[0001] This invention relates to the field of displays, and particularly to a pixel circuit, driving method, and display device. Background Technology

[0002] Currently, Micro-LED (Micro Light Emitting Diode) displays, with pixel light-emitting unit sizes smaller than 100 micrometers, are poised to become the next generation of mainstream semiconductor display technology due to their advantages such as high contrast, fast response speed, low power consumption, and long lifespan. Mini-LED, with pixel light-emitting unit sizes between 100 and 200 micrometers, is a relatively mature technology. As a display backlight, it can be combined with TFT-LCD technology to significantly improve the contrast of TFT-LCD displays and reduce display power consumption.

[0003] Meanwhile, for existing pixel circuits, compared to using amorphous silicon TFTs, oxide TFTs offer advantages such as higher mobility, better uniformity, and extremely low off-state leakage current, making them suitable for large-area, low-cost Micro-LED / Mini-LED displays. However, oxide TFTs are prone to threshold voltage drift after long-term use, resulting in threshold voltage dispersion between different batches and different locations on the display. These issues can lead to instability in Micro-LED / Mini-LED displays after prolonged operation or deviations between display samples. Furthermore, a large driving current on the driving backplane can also cause V... DD and V SS There is a large IR drop / rise on the line, which affects the uniformity of the luminous current.

[0004] Figure 1 This is a schematic diagram of the structure of a pixel circuit in the prior art. Figure 2 yes Figure 1 The timing diagram of the pixel circuit is shown. Figure 1 and Figure 2 As shown, this pixel circuit utilizes a diode-like connection structure to achieve control over threshold voltage drift and non-uniformity, as well as V... SS IR rise compensation, and using capacitive coupling to increase the Vo of the switching transistor in the light-emitting branch. GS To reduce its V DS This reduces the voltage across the light-emitting branch, thereby lowering power consumption. However, this pixel circuit uses pulse amplitude modulation, so it cannot guarantee that Micro-LED / Mini-LED operates at the current density with the highest luminous efficiency, which is not conducive to reducing power consumption. In addition, besides the driving TFT (T2), the light-emitting branch also has a switching TFT (T1), which increases the voltage across the branch and is also not conducive to reducing power consumption. Summary of the Invention

[0005] In view of the above problems, the present application provides a pixel circuit, a driving method and a display device, which can realize compensation for threshold voltage drift and non-uniformity, IR rise, reduce power consumption and improve display quality. SS IR rise compensation, reduce power consumption, and improve display quality.

[0006] The pixel circuit provided by the embodiment of the present application comprises a pulse amplitude modulation module, a light emitting element and a pulse width modulation module, the pulse amplitude modulation module comprises a first driving switch module, a first reset module, a first storage capacitor, a first compensation module and an amplitude modulation driving module. The first end of the first driving switch module receives a first reference voltage, the second end of the first driving switch module receives a second reference voltage sent by the first reset module in an initialization stage, the control end of the first driving switch module receives a third reference voltage before a light emitting stage, and the difference between the third reference voltage and the second reference voltage is greater than the first threshold voltage of the first driving switch module. The first end of the first storage capacitor is connected with the second end of the first driving switch module. The second end of the first compensation module is connected with the control end of the first driving switch module, and the control end of the first compensation module receives a light emitting signal. The amplitude modulation driving module provides an amplitude modulation data voltage to the second end of the first storage capacitor in the initialization stage and a first threshold compensation stage. The first end of the light emitting element is connected with the second end of the first driving switch module, and the second end of the light emitting element receives a fourth reference voltage. The pulse width modulation module is used for controlling the voltage of the control end of the first driving switch module to control the light emitting time length in the light emitting stage.

[0007] Specifically, the pulse width modulation module comprises a second drive switch module, a second reset module, a second storage capacitor, a width driving module, a light-emitting switch module and a second compensation module; a first end of the second drive switch module is configured to control a voltage of a control end of the first drive switch module in a light-emitting stage, a second end of the second drive switch module is configured to receive a fifth reference voltage, a control end of the second drive switch module is configured to receive a sixth reference voltage sent by the second reset module in the initialization stage, and a difference between the sixth reference voltage and the fifth reference voltage is greater than a first threshold voltage of the first drive switch module; a first end of the second compensation module is connected with the first end of the second drive switch module, a second end of the second compensation module is connected with the control end of the second drive switch module, and the second compensation module is set to be in a conductive state in a second threshold compensation stage; a first end of the second storage capacitor is connected with the control end of the second drive switch module; the width driving module is configured to provide a width driving data voltage to a second end of the second storage capacitor in the second threshold compensation stage; and the light-emitting switch module is configured to provide a switch control signal to the second end of the second storage capacitor according to the light-emitting signal in the light-emitting stage.

[0008] Specifically, the pixel circuit further comprises a connection module; a first end of the connection module is connected with the control end of the first drive switch module, a second end of the connection module is connected with the first end of the second drive switch module, and a control end of the connection module is configured to receive the light-emitting signal.

[0009] Specifically, the pixel circuit further comprises a connection module; a first end of the connection module is connected with the control end of the first drive switch module, a second end of the connection module is connected with the first end of the second drive switch module, and a control end of the connection module is configured to receive the light-emitting signal.

[0010] Specifically, the pulse amplitude modulation module further comprises a third reset module; a first end of the third reset module is connected with the control end of the first drive switch module, a second end of the third reset module is configured to receive the third reference voltage, and the third reset module is configured to provide the third reference voltage to the control end of the first drive switch module in an initialization stage.

[0011] Specifically, the first threshold compensation stage and the second threshold compensation stage are the same time period. The first reset module and the second reset module both receive a first scan signal; the amplitude driving module and the third reset module both receive a second scan signal; the width driving module and the second compensation module both receive a third scan signal; the light-emitting switch module, the connection module and the first compensation module all receive a light-emitting signal.

[0012] Specifically, the first end of the second driving switch module is connected with the control end of the first driving switch module, the third reference voltage and the fifth reference voltage are equal in voltage, and the first threshold compensation stage is arranged before the second threshold compensation stage.

[0013] Specifically, the first reset module and the second reset module both receive a first scan signal, the amplitude modulation driving module receives a second scan signal, the pulse width modulation driving module and the second compensation module both receive a third scan signal, and the light-emitting switch module and the first compensation module both receive the light-emitting signal.

[0014] Specifically, the pulse amplitude modulation module further comprises a fourth reset module, the first end of the fourth reset module is connected with the second end of the first driving switch module, the second end of the fourth reset module receives the second reference voltage, and the fourth reset module is set to an on state in the second threshold compensation stage.

[0015] The embodiment of the present application further provides a driving method of a pixel circuit, which applies the pixel circuit. The driving method of the pixel circuit comprises the following steps: in the initialization stage, the second end of the first driving switch module receives the second reference voltage; in the first threshold compensation stage, the first driving switch module is turned on according to the third reference voltage, so that the voltage of the second end of the first driving switch module gradually approaches the third reference voltage until the difference is the first threshold voltage; and the amplitude modulation driving module provides the amplitude modulation data voltage to the second end of the first storage capacitor; in the light-emitting stage, the first compensation module is turned on according to the light-emitting signal, and the first compensation module and the first storage capacitor perform threshold compensation of the first driving switch module and writing of the amplitude modulation data voltage, so as to realize accurate modulation of the light-emitting current size in the light-emitting stage; meanwhile, the pulse width modulation module controls the voltage of the control end of the first driving switch module to control the light-emitting duration.

[0016] Specifically, the pixel circuit comprises a connection module, the first end of the connection module is connected with the pulse amplitude modulation module, the second end of the connection module is connected with the pulse width modulation module, and the control end of the connection module receives the light-emitting signal; the driving method further comprises the following steps: before the light-emitting stage, the connection module disconnects the pulse width modulation module and the pulse amplitude modulation module, so that the pulse width modulation of the pulse width modulation module and the pulse amplitude modulation of the pulse amplitude modulation module do not interfere with each other; in the light-emitting stage, the connection module turns on the pulse width modulation module and the pulse amplitude modulation module according to the light-emitting signal.

[0017] Specifically, the pulse width modulation module and the pulse amplitude modulation module are directly connected; the driving method further comprises: in the first threshold compensation stage, the pulse width modulation module provides the third reference voltage; in the second threshold compensation stage, the pulse width modulation module performs pulse width modulation, wherein the second threshold compensation stage is arranged after the first threshold compensation stage.

[0018] The embodiment of the present application also provides a display device comprising the pixel circuit.

[0019] The pixel circuit, the driving method and the display device provided by the embodiment of the present application, in the initialization stage, the second end of the first driving switch module receives the second reference voltage; before the light-emitting stage, the control end of the first driving switch module receives the third reference voltage, the difference between the third reference voltage and the second reference voltage is greater than the first threshold voltage of the first driving switch module, and the two ends of the first storage capacitor can respectively perform threshold compensation of the first driving switch module and writing of the amplitude modulation data voltage, so that in the light-emitting stage, the first compensation module is turned on to change the voltage of the control end of the first driving switch module, threshold compensation and writing of the amplitude modulation data voltage are realized, that is, the pulse width modulation driving method is adopted, the light-emitting element can work at the current density with the maximum light-emitting efficiency, which is also beneficial to reducing power consumption, the pixel circuit can realize accurate modulation of the size of the light-emitting current in the light-emitting stage according to the amplitude modulation data voltage, and the display quality is improved. Moreover, the light-emitting branch in the pixel circuit does not have an additional driving module except the first driving switch module, the cross voltage of the light-emitting branch is reduced, and thus the power consumption is reduced.

[0020] In addition, the second end of the second driving switch module can receive the fifth reference voltage, and the control end of the second driving switch module can receive the sixth reference voltage in the initialization stage, the difference between the sixth reference voltage and the fifth reference voltage is greater than the second threshold voltage of the second driving switch module; threshold compensation of the second driving switch module and writing of the width modulation data voltage are performed through the second compensation module and the second storage capacitor, wherein the second compensation module is arranged between the first end and the control end of the second driving switch module, forms a structure similar to a diode connection, and realizes threshold compensation; the first end of the second storage capacitor is connected with the control end of the second driving switch module, and the second end of the second storage capacitor receives the width modulation data voltage, to realize accurate modulation of the light-emitting duration in the light-emitting stage.

[0021] In order to make the above and other objects, features and advantages of the present application more apparent, more fully understood, and more readily practiced, the following will describe in detail and preferably implement embodiments, and combine with the attached drawings, as follows. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of a pixel circuit of the prior art.

[0023] Figure 2 is Figure 1 a timing diagram of the pixel circuit shown in FIG. 1.

[0024] Figure 3 is a structural diagram of the pixel circuit of the first embodiment of the present application.

[0025] Figure 4 is Figure 3 a timing diagram of the pixel circuit shown in FIG. 2.

[0026] Figure 5 is a structural diagram of the pixel circuit of the second embodiment of the present application.

[0027] Figure 6 is Figure 5 a timing diagram of the pixel circuit shown in FIG. 3.

[0028] Figure 7 is a structural diagram of the pixel circuit of the third embodiment of the present application.

[0029] Figure 8 is Figure 7 a timing diagram of the pixel circuit shown in FIG. 4.

[0030] Figure 9 is a flowchart of the driving method of the pixel circuit of the fourth embodiment of the present application. DETAILED DESCRIPTION

[0031] For further illustrating the technical means and effects taken by the present application to achieve the intended purposes, the specific embodiments, methods, steps, structures, features and effects of the pixel circuit according to the present application are described in detail as follows in combination with the drawings and preferred embodiments.

[0032] The foregoing and other technical contents, features and effects of the present application will be clearly presented in the following detailed description of the preferred embodiments in combination with the drawings. Through the description of the specific embodiments, the technical means and effects taken by the present application to achieve the intended purposes can be understood more deeply and specifically. However, the drawings are provided for reference and illustration only, and are not used to limit the present application.

[0033] Figure 3 is a structural diagram of the pixel circuit of the first embodiment of the present application. As shown in FIG. 1, the present embodiment provides a pixel circuit, which includes a pulse amplitude modulation module 13, a light emitting element LED and a pulse width modulation module 11. In the present embodiment, the light emitting element LED is, for example, a micro light emitting diode (Micro-LED). In other embodiments, it can also be an organic light emitting diode (OLED), a mini light emitting diode (mini LED) or other light emitting elements, which are not limited herein. Figure 3 a timing diagram of the pixel circuit shown in FIG. 2.

[0034] The pulse amplitude modulation module 13 includes a first drive switch module T1, a first reset module T3, a first storage capacitor C1, a first compensation module T5, and an amplitude modulation drive module T6. The first terminal of the first drive switch module T1 receives a first reference voltage V. DD1 The second terminal of the first drive switch module T1 receives the second reference voltage V sent by the first reset module T3 during the initialization phase. L The control terminal of the first drive switch module T1 receives the third reference voltage V before the light emission stage. REF1 The third reference voltage V REF1 With the second reference voltage V L The difference is greater than the first threshold voltage V of the first drive switch module T1. TH，T1 The first terminal of the first storage capacitor C1 is connected to the second terminal of the first drive switch module T1; the first terminal of the first compensation module T5 is connected to the second terminal of the first storage capacitor C1, and the second terminal of the first compensation module T5 is connected to the control terminal of the first drive switch module T1. The control terminal of the first compensation module T5 receives the light emission signal EM; the amplitude modulation drive module T6 provides the amplitude modulation data voltage V during the initialization phase and the first threshold compensation phase. DATA(PAM) To the second terminal of the first storage capacitor C1.

[0035] The first terminal of the light-emitting element LED is connected to the second terminal of the first driving switch module T1, and the second terminal of the light-emitting element LED receives the fourth reference voltage V. SS .

[0036] The pulse amplitude modulation module 13 is used to control the voltage at the control terminal of the first drive switch module T1 during the light emission stage to control the light emission duration.

[0037] Specifically, such as Figure 3 As shown, to facilitate the explanation of the working process of the embodiment, the second end of the first drive switch module T1 can be set as the first node A, the control end of the first drive switch module T1 can be set as the second node B, and the second end of the first storage capacitor C1 can be set as the third node C.

[0038] First, during the initialization phase, the first node A receives the second reference voltage V sent by the first reset module T3. L Among them, a second reference voltage V is set. L With the fourth reference voltage V SS When applied across the two ends of the LED, the LED does not conduct and emit light; therefore, a second reference voltage V is preferable. L It is a negative voltage. Simultaneously, the amplitude modulation drive module T6 provides the amplitude modulation data voltage V. DATA(PAM)to the third node C. Then the first end of the first storage capacitor C1 is connected to the first node A, i.e. the voltage at the first end of the first storage capacitor C1 is the second reference voltage V L ; the second end of the first storage capacitor C1 is connected to the third node C, i.e. the voltage at the second end of the first storage capacitor C1 is the amplitude-modulated data voltage V DATA(PAM) .

[0039] Then, in the first threshold compensation stage, the first reset module T3 stops sending the second reference voltage V L to the first node A, while the control end of the first drive switch module T1 receives the third reference voltage V REF1 , wherein the third reference voltage V REF1 is set to be greater than the second reference voltage V L by a first threshold voltage V TH，T1 of the first drive switch module T1. Then the first drive switch module T1 is turned on, and the voltage at the first node A gradually approaches the voltage at the second node B until the first drive switch module T1 is turned off, at which time the voltage at the first node A differs from the voltage at the second node B by the first threshold voltage V TH，T1 . Meanwhile, the amplitude-modulated drive module T6 still provides the amplitude-modulated data voltage V DATA(PAM) to the third node C, so that the voltage at the third node C remains at the amplitude-modulated data voltage V DATA(PAM) . Then the first end of the first storage capacitor C1 is connected to the first node A, i.e. the voltage at the first end of the first storage capacitor C1 differs from the third reference voltage V REF1 by a first threshold voltage V TH，T1 ; the second end of the first storage capacitor C1 is connected to the third node C, i.e. the voltage at the second end of the first storage capacitor C1 is the amplitude-modulated data voltage V DATA(PAM) .

[0040] Finally, in the light-emitting stage, the control end of the first compensation module T5 receives a light-emitting signal EM, and the first compensation module T5 turns on the second node B and the third node C, so that the voltage at the control end of the first drive switch module T1 immediately rises according to the amplitude-modulated data voltage V DATA(PAM) , causing the potential at the first node A to immediately rise and be sufficient to turn on the light-emitting element LED. At this time, the voltage at the first node A differs from the fourth reference voltage V SS by the turn-on voltage of the light-emitting element LED, and the voltage difference between the control end and the second end of the first drive switch module T1 is related to the voltage difference across the first storage capacitor C1, i.e. the threshold compensation of the first drive switch module T1 and the writing of the amplitude-modulated data voltage V DATA(PAM) are performed through the first compensation module T5 and the first storage capacitor C1. Thus, the current at the second end of the first drive switch module T1, through threshold compensation, differs from the first threshold voltage V TH，T1If not, the pixel circuit can write the amplitude modulation data voltage V DATA(PAM) The pixel circuit of the embodiment can realize precise modulation of the size of the light-emitting current in the light-emitting stage. Meanwhile, the pulse width modulation module 11 can control the voltage at the control end of the first drive switch module T1 to control the light-emitting duration.

[0041] In the initialization stage, the pixel circuit of the embodiment sets the second end of the first drive switch module T1 to receive the second reference voltage V L Before the light-emitting stage, the pixel circuit of the embodiment sets the control end of the first drive switch module T1 to receive the third reference voltage V REF1 The difference between the third reference voltage V REF1 and the second reference voltage V L is greater than the first threshold voltage of the first drive switch module T1, and the two ends of the first storage capacitor C1 can respectively perform threshold compensation of the first drive switch module T1 and writing of the amplitude modulation data voltage V DATA(PAM) Therefore, in the light-emitting stage, the first compensation module T5 is turned on to change the voltage at the control end of the first drive switch module T1, to realize threshold compensation and writing of the amplitude modulation data voltage V DATA(PAM) Therefore, the pixel circuit can realize precise modulation of the size of the light-emitting current in the light-emitting stage according to the amplitude modulation data voltage V DATA(PAM) , and improve the display quality. Moreover, the light-emitting branch in the pixel circuit does not have an additional drive module except the first drive switch module T1, which reduces the cross voltage of the light-emitting branch and thus reduces the power consumption.

[0042] It should be understood that, Figure 3 In the pixel circuit shown in the figure, only the first reference voltage V DD1 and the sixth reference voltage V DD2 are the power supply voltage at high level, the fourth reference voltage V SS is at low level, i.e., ground, and the first drive switch module T1 is an n-type TFT, which can be more suitable for the pixel circuit based on oxide TFT. However, the embodiment is not limited thereto, for example, the first reference voltage V DD1 and the sixth reference voltage V DD2 may be at low level, i.e., ground, and the fourth reference voltage V SS may be the power supply voltage at high level, and the first drive switch module T1 can be a p-type TFT, etc., and the technical solutions thereof all fall within the protection scope of the present application.

[0043] In an embodiment of the present application, as Figure 3As shown, the pixel circuit further comprises a connecting module 12, a first end of the connecting module 12 is connected with the pulse amplitude modulation module 13, a second end of the connecting module 12 is connected with the pulse width modulation module 11, and a control end of the connecting module 12 receives the light-emitting signal EM. Specifically, before the light-emitting stage, the control end of the connecting module 12 does not receive the light-emitting signal EM, the connecting module 12 disconnects the pulse width modulation module 11 and the pulse amplitude modulation module 13, the pulse width modulation module 11 can perform pulse width modulation, the pulse amplitude modulation module can perform pulse amplitude modulation, and the two do not interfere with each other. In the light-emitting stage, the control end of the connecting module 12 receives the light-emitting signal EM, the connecting module 12 connects the pulse width modulation module 11 and the pulse amplitude modulation module 13 in conduction, and the pulse width modulation module 11 can output a pulse width modulation signal to the pulse amplitude modulation module 13 to control the light-emitting time length, so that the pulse width modulation driving method can ensure that the light-emitting element LED works at the current density with the maximum light-emitting efficiency, and is also conducive to reducing power consumption. In addition, the use of the connecting module 12 can enable the threshold voltage compensation and data writing of the pulse width modulation module 11 and the pulse amplitude modulation module 13 to be performed at the same time without interfering with each other, so that the circuit timing can be simplified.

[0044] In an embodiment of the application, as shown in Figure 3 The pulse width modulation module 11 comprises a second driving switch module T2, a second reset module T8, a second storage capacitor C2, a width adjustment driving module T9, a light-emitting switch module T10, and a second compensation module T7. The first end of the second driving switch module T2 is used to control the voltage of the control end of the first driving switch module T1 in the light-emitting stage, the second end of the second driving switch module T2 receives the fifth reference voltage V REF2 , the control end of the second driving switch module T2 receives the sixth reference voltage V DD2 sent by the second reset module T8 in the initialization stage, and the difference between the sixth reference voltage V DD2 and the fifth reference voltage V REF2 is greater than the first threshold voltage V TH，T1 of the first driving switch module T1. The first end of the second compensation module T7 is connected with the first end of the second driving switch module T2, the second end of the second compensation module T7 is connected with the control end of the second driving switch module T2, and the second compensation module T7 is set to a conduction state in the second threshold compensation stage. The first end of the second storage capacitor C2 is connected with the control end of the second driving switch module T2. The width adjustment driving module T9 is used to provide a width adjustment data voltage V DATA(PWM) to the second end of the second storage capacitor C2 in the second threshold compensation stage. The light-emitting switch module T10 is used to provide a switch control signal to the second end of the second storage capacitor C2 according to the light-emitting signal EM in the light-emitting stage.

[0045] In one embodiment of the invention, such as Figure 3 As shown, the pixel circuit also includes a connection module 12, which may include a switching element T11; the first end of the connection module 12 is connected to the control end of the first driving switch module T1, the second end of the connection module 12 is connected to the first end of the second driving switch module T2, and the control end of the connection module 12 receives the light emission signal EM.

[0046] In one embodiment of the invention, such as Figure 3 As shown, the pulse amplitude modulation module 13 also includes a third reset module T4. The first terminal of the third reset module T4 is connected to the control terminal of the first drive switch module T1, and the second terminal of the third reset module T4 receives the third reference voltage V. REF1 The third reset module T4 provides the third reference voltage V during the initialization phase. REF1 To the control terminal of the first drive switch module T1.

[0047] In one embodiment of the invention, such as Figure 3 As shown, the first reset module T3 and the second reset module T8 both receive the first scan signal S1; the amplitude modulation drive module T6 and the third reset module T4 both receive the second scan signal S2; the width modulation drive module T9 and the second compensation module T7 both receive the third scan signal S3; the light-emitting switch module T10, the connection module 12 and the first compensation module T5 all receive the light-emitting signal EM.

[0048] In one embodiment of the invention, such as Figure 4 The timing diagram shown indicates that the first threshold compensation stage and the second threshold compensation stage are within the same time period.

[0049] Specifically, the following only uses the first reference voltage V DD1 and the sixth reference voltage V DD2 Both are high-level power supply voltages, and the fourth reference voltage V SS As an example of an n-type TFT, the working process of one embodiment is divided into the following three stages: initialization stage, threshold voltage compensation and data writing stage, and light emission stage. The threshold voltage compensation and data writing stage can be corresponding to the first threshold compensation stage and the second threshold compensation stage, which are in the same time period.

[0050] (1) Initialization phase: The first scan signal S1 and the second scan signal S2 are at high level, and the remaining signals are at low level, thereby turning on the first reset module T3, the third reset module T4, the amplitude modulation drive module T6, and the second reset module T8, and the second reference voltage V. L The first reset module T3 is applied to the first node A. In actual use, the second reference voltage V needs to be set. LThe voltage is less than the threshold voltage of the LED, ensuring that the LED does not emit light during the initialization phase. Additionally, the third reference voltage V... REF1 The sixth reference voltage V is applied to the second node B via the third reset module T4. DD2 The reset is applied to the fourth node D, i.e., the control terminal of the second drive switch module T2, through the second reset module T8.

[0051] (2) Threshold voltage compensation and data writing stage: Except for the second scan signal S2 and the third scan signal S3, all other signals are at low level, while the second scan signal S2 and the third scan signal S3 are at high level, thereby turning on the third reset module T4, the amplitude modulation drive module T6, the second compensation module T7, and the width modulation drive module T9, and the amplitude modulation data voltage V DATA(PAM) The amplitude modulation drive module T6 applies voltage to the third node C. Because the third reset module T4 is turned on, the potential of the second node B is maintained at the third reference voltage V. REF1 In practical use, a third reference voltage V needs to be set. REF1 With the second reference voltage V L The difference (V) REF1 -V L The voltage V is greater than the first threshold voltage V of the first drive switch module T1. TH，T1 Therefore, at the beginning of this stage, the first drive switch module T1 is turned on, and the potential of the first node A will be determined by the second reference voltage V. L Gradually rise to (V) REF1 -V TH，T1 Until the first drive switch module T1 is turned off, at the end of this stage, the voltage stored across the first storage capacitor C1 is as follows:

[0052] V C1 =V DATA(PAM) -(V REF1 -V TH，T1 )

[0053] Regarding the pulse width modulation module 11, at this stage, because the second compensation module T7 is turned on, the gate and drain of the second drive switch module T2 are connected, forming a structure similar to a diode connection. In actual use, a sixth reference voltage V needs to be set. DD2 With the fifth reference voltage V REF2 The difference (V) DD2 -V REF2 The voltage V is greater than the second threshold voltage V of the second drive switch module T2. TH，T2 Therefore, at the beginning of this stage, the second drive switch module T2 is turned on, and the potential of the fourth node D will gradually decrease to (V). REF2 +V TH，T2) until the second drive switch module T2 is turned off. At the same time, the width-modulated data voltage V DATA(PWM) is applied to the fifth node E, i.e. the second terminal of the second storage capacitor C2, by the width-modulating drive module T9. Thus, at the end of this stage, the voltage stored across the second storage capacitor C2 is as follows:

[0054] V C2 = V DATA(PWM) + V REF2 + V TH，T2

[0055] (3) Light-emitting stage: all signals are low except the light-emitting signal EM which is high, thus turning on the first compensation module T5, the light-emitting switch module T10 and the connecting module 12. Since the first compensation module T5 is turned on, the second node B and the third node C are connected together as one point, and the gate-source voltage of the first drive switch module T1 is equal to the voltage stored across the first storage capacitor C1 in the previous stage. In actual use, this voltage is set to be higher than the first threshold voltage V TH，T1 of the first drive switch module T1, so the first drive switch module T1 is turned on at the beginning of this stage, and a driving current flows through the light-emitting element LED to make it emit light. The first terminal of the light-emitting element LED is connected to the first node A, and its voltage rises to V LED . Due to the coupling effect of the first storage capacitor C1, the potentials of the second node B and the third node C also rise by the same value as the potential of the first node A:

[0056] V B = V C = V C1 + V A = V DATA(PAM) + V REF1 -V TH，T1 + V LED

[0057] Thus, the gate-source voltage of the first drive switch module T1 is still equal to the voltage stored across the first storage capacitor C1 in the first threshold compensation stage:

[0058] V GS，T1 = V B -V A = V C1 = V DATA(PAM) -V REF1 -V TH，T1

[0059] Thus, the size of the light-emitting current is as follows:

[0060] I LED = 0.5k(V​​GS，T1 -V TH，T1 ) 2 = 0.5k(V DATA(PAM) -V REF1 ) 2

[0061] where k = μCOX(W / L)T1, μ is carrier mobility, COX is the unit area gate oxide capacitance, and (W / L)T1 is the width-length ratio of the first drive switch module T1. The light-emitting current formula does not contain V TH，T1 and V SS , so the light-emitting current size is independent of the first threshold voltage V TH，T1 and the fourth reference voltage V SS .

[0062] As for the pulse width modulation module 11, the ramp signal is applied to the fifth node E through the light-emitting switch module T10, and the potential of the fifth node E becomes VSWEEP. Due to the coupling effect of the second storage capacitor C2, the potential of the fourth node D becomes:

[0063] V D = V E -V C2 = V SWEEP -V DATA(PWM) +(V REF2 +V TH，T2 )

[0064] V GS，T2 = V D -V REF2 = V SWEEP -V DATA(PWM) +V TH，T2

[0065] When the gate-source voltage V GS，T2 >V TH，T2 of the second drive switch module T2, the second drive switch module T2 is turned on, and the second node B potential is pulled down to VREF2 , the first drive switch module T1 is turned off, and the LED stops emitting light, at this time V SWEEP >V DATA(PWM) , so it can be seen that the light-emitting duration is determined by the width modulation data voltage V DATA(PWM) , and is independent of the second threshold voltage V TH，T2 .

[0066] The pixel circuit of the embodiment can also make the threshold voltage compensation of the pulse amplitude modulation module 13 and the pulse width modulation module 11 part and the data writing at the same time without interfering with each other due to the use of the connection module 12, thereby simplifying the circuit timing. Among them, the second end of the second drive switch module T2 can be arranged to receive the fifth reference voltage V REF2The control end of the second driving switch module T2 is arranged to receive the sixth reference voltage V DD2 The difference between the sixth reference voltage V DD2 and the fifth reference voltage V REF2 is greater than the second threshold voltage of the second driving switch module T2; the threshold compensation of the second driving switch module T2 and the writing of the width-modulated data voltage V DATA(PWM) are performed through the second compensation module T7 and the second storage capacitor C2, wherein the second compensation module T7 is arranged between the first end and the control end of the second driving switch module T2, forming a structure similar to a diode connection, so as to realize threshold compensation; the first end of the second storage capacitor C2 is connected with the control end of the second driving switch module T2, and the second end of the second storage capacitor C2 receives the width-modulated data voltage V DATA(PWM) , so as to realize accurate modulation of the light-emitting duration in the light-emitting stage.

[0067] Figure 5 is a structure schematic diagram of a pixel circuit of a second embodiment of the present application, Figure 6 is Figure 5 a timing schematic diagram of the pixel circuit shown in Figure 5 and Figure 6 , the present embodiment provides a pixel circuit, the basic structure and principle and the generated technical effects are the same as those of the first embodiment, for brief description, the part not mentioned in the present embodiment can be referred to the corresponding content in the first embodiment.

[0068] In an embodiment of the present application, please refer to Figure 5 and Figure 6 , the first end of the second driving switch module T2 is connected with the control end of the first driving switch module T1, the third reference voltage V REF1 and the fifth reference voltage V REF2 are equal in voltage, and the first threshold compensation stage is arranged before the second threshold compensation stage.

[0069] In an embodiment of the present application, please refer to Figure 5 and Figure 6 , the first reset module T3 and the second reset module T8 both receive the first scan signal S1; the amplitude modulation driving module T6 receives the second scan signal S2; the width modulation driving module T9 and the second compensation module T7 both receive the third scan signal S3; the light-emitting switch module T10 and the first compensation module T5 both receive the light-emitting signal EM.

[0070] Specifically, the working process of the present embodiment is divided into the following three stages: an initialization stage, a threshold voltage compensation and data writing stage, and a light-emitting stage, wherein the threshold voltage compensation and data writing stage can be divided into a first threshold compensation stage and a second threshold compensation stage.

[0071] (1) Initialization phase: The first scan signal S1 and the second scan signal S2 are at high level, and the remaining signals are at low level, thereby turning on the first reset module T3, the amplitude modulation drive module T6, and the second reset module T8, and the second reference voltage V. L The first reset module T3 is applied to the first node A. In actual use, the second reference voltage V needs to be set. L The voltage is less than the threshold voltage of the LED, ensuring that the LED does not emit light during the initialization phase. Additionally, the sixth reference voltage V... DD2 The reset is applied to the fourth node D, i.e., the control terminal of the second drive switch module T2, through the second reset module T8.

[0072] (2) First threshold compensation stage

[0073] The threshold voltage compensation and data writing stage can be divided into a first threshold compensation stage and a second threshold compensation stage. In the first threshold compensation stage, all signals except the second scan signal S2 are at a low level, while the second scan signal S2 is at a high level, thereby turning on the amplitude modulation drive module T6 and increasing the amplitude modulation data voltage V. DATA(PAM) The amplitude modulation drive module T6 applies voltage to the third node C. Due to the effect of the second storage capacitor C2, the potential of the fourth node D remains at the sixth reference voltage V. DD2 A sixth reference voltage V needs to be set. DD2 With the fifth reference voltage V REF2 The difference (V) DD2 -V REF2 The voltage V is greater than the second threshold voltage V of the second drive switch module T2. TH，T2 Therefore, at the beginning of this stage, the second drive switch module T2 is turned on, allowing the second node B to receive the fifth reference voltage V through the turned-on second drive switch module T2. REF2 In practical use, because the first drive switch module T1 needs to be set to receive the third reference voltage V... REF1 Set the fifth reference voltage V REF2 With the third reference voltage V REF1 The voltage magnitudes are equal, and this third reference voltage V REF1 With the second reference voltage V L The difference (V) REF1 -V L The voltage V is greater than the first threshold voltage V of the first drive switch module T1. TH，T1 Therefore, at the beginning of this stage, the first drive switch module T1 is turned on, and the potential of the first node A will be determined by the second reference voltage V. L Gradually rise to (V) REF1 -V TH，T1 Until the first drive switch module T1 is turned off, at the end of this stage, the voltage stored across the first storage capacitor C1 is as follows:

[0074] V C1 = V DATA(PAM) -(V REF1 -V TH，T1 ).

[0075] (3) Second threshold compensation stage

[0076] In the second threshold compensation stage, all signals are low except the third scan signal S3 which is high, thus turning on the second compensation module T7 and the pulse width modulation module T9. In this stage, because the second compensation module T7 is turned on, the gate and the drain of the second drive switch module T2 are connected, forming a structure similar to a diode connection. The second drive switch module T2 is turned on, and the fourth node D potential will gradually decrease to (V REF1 + V TH，T2 ) until the second drive switch module T2 is turned off. At the same time, the pulse width modulation data voltage V DATA(PWM) is applied to the fifth node E, i.e. the second end of the second storage capacitor C2, through the pulse width modulation module T9. Therefore, at the end of this stage, the voltage stored across the second storage capacitor C2 is as follows:

[0077] V C2 = V DATA(PWM) -(V REF1 + V TH，T2 )

[0078] (4) Light emitting stage: all signals are low except the light emitting signal EM which is high, thus turning on the first compensation module T5 and the light emitting switch module T10. Because the first compensation module T5 is turned on, the second node B and the third node C are connected to one point, and the gate-source voltage of the first drive switch module T1 is equal to the voltage stored across the first storage capacitor C1 in the last stage. In actual use, this voltage is set to be higher than the first threshold voltage V TH，T1 of the first drive switch module T1, so the first drive switch module T1 is turned on at the beginning of this stage, and the drive current flows through the light emitting element LED to make it emit light. The first end of the light emitting element LED is the first node A, and its voltage will rise to V LED . Because of the coupling effect of the first storage capacitor C1, the potentials of the second node B and the third node C will also rise by the same value as the potential of the first node A:

[0079] V B = V C = V C1 + V A = V DATA(PAM) -(V REF1 -V TH，T1 )+ VLED

[0080] Therefore, the gate-source voltage of the first drive switch module T1 is still equal to the voltage stored across the first storage capacitor C1 in the first threshold compensation stage:

[0081] V GS，T1 = V B -V A = V C1 = V DATA(PAM) -(V REF1 -V TH，T1 )

[0082] Therefore, the luminous current is as follows:

[0083] I LED = 0.5k(V GS，T1 -V TH，T1 ) 2 = 0.5k(V DATA(PAM) -V REF1 ) 2

[0084] where k = μCOX(W / L)T1, μ is the carrier mobility, COX is the unit area gate oxide layer capacitance, and (W / L)T1 is the width-length ratio of the first drive switch module T1. The luminous current formula does not contain V TH，T1 and V SS , so the luminous current size is irrelevant to the first threshold voltage V TH，T1 and the fourth reference voltage V SS .

[0085] As for the pulse width modulation module 21, the ramp signal is applied to the fifth node E through the luminous switch module T10, and the potential of the fifth node E becomes VSWEEP. Due to the coupling effect of the second storage capacitor C2, the potential of the fourth node D becomes:

[0086] V D = V E -V C2 = V SWEEP -V DATA(PWM) +(V REF1 +V TH，T2 )

[0087] V GS，T2 = V D -V REF1 = V SWEEP -V DATA(PWM) +V TH，T2

[0088] When the gate-source voltage V GS，T2 > V TH，T2When the pixel circuit is in the light-emitting stage, the second drive switch module T2 is turned on, the second node B is pulled down to V REF1 , the first drive switch module T1 is turned off, and the LED stops emitting light. At this time, V SWEEP >V DATA(PWM) Therefore, it can be seen that the light-emitting duration is determined by the width-modulated data voltage V DATA(PWM) , and is irrelevant to the second threshold voltage V TH，T2 .

[0089] The pixel circuit of the embodiment directly couples the pulse width modulation module 21 and the pulse amplitude modulation module 22, thereby saving the TFTs and control signals for coupling; the second drive switch module T2 resets the second node B of the pulse amplitude modulation module 22 to provide the voltage V REF1 , thereby saving the third reset module T4 and the third reference voltage V REF1 provided in the first embodiment.

[0090] Figure 7 is a structural schematic diagram of a pixel circuit of a third embodiment of the present application, Figure 8 is a timing schematic diagram of the pixel circuit shown in Figure 7 . Please refer to Figure 7 and Figure 8 , the embodiment provides a pixel circuit, the basic structure and principle and the technical effects generated are the same as those of the second embodiment. For brevity, the part not mentioned in the embodiment can be referred to the corresponding content in the first embodiment.

[0091] In an embodiment of the present application, please refer to Figure 7 and Figure 8 , the pulse amplitude modulation module 32 further includes a fourth reset module T12, the first end of the fourth reset module T12 is connected with the second end of the first drive switch module T1, the second end of the fourth reset module T12 receives the second reference voltage V L , and the fourth reset module T12 is set to be in the on state in the second threshold compensation stage.

[0092] Specifically, the working process of the embodiment is divided into the following three stages: an initialization stage, a threshold voltage compensation and data writing stage, and a light-emitting stage. The threshold voltage compensation and data writing stage can be divided into a first threshold compensation stage and a second threshold compensation stage.

[0093] (1) Initialization stage: the first scan signal S1 and the second scan signal S2 are high, and the rest of the signals are low, thereby turning on the first reset module T3, the amplitude modulation drive module T6, and the second reset module T8. The second reference voltage V L is applied to the first node A through the first reset module T3. In actual use, the second reference voltage V LThe voltage is less than the threshold voltage of the LED, ensuring that the LED does not emit light during the initialization phase. Additionally, the sixth reference voltage V... DD2 The reset is applied to the fourth node D, i.e., the control terminal of the second drive switch module T2, through the second reset module T8.

[0094] (2) First threshold compensation stage

[0095] The threshold voltage compensation and data writing stage can be divided into a first threshold compensation stage and a second threshold compensation stage. In the first threshold compensation stage, all signals except the second scan signal S2 are at a low level, while the second scan signal S2 is at a high level, thereby turning on the amplitude modulation drive module T6 and increasing the amplitude modulation data voltage V. DATA(PAM) The amplitude modulation drive module T6 applies voltage to the third node C. Due to the effect of the second storage capacitor C2, the potential of the fourth node D remains at the sixth reference voltage V. DD2 A sixth reference voltage V needs to be set. DD2 With the fifth reference voltage V REF2 The difference (V) DD2 -V REF2 The voltage V is greater than the second threshold voltage V of the second drive switch module T2. TH，T2 Therefore, at the beginning of this stage, the second drive switch module T2 is turned on, allowing the second node B to receive the fifth reference voltage V through the turned-on second drive switch module T2. REF2 In practical use, because the first drive switch module T1 needs to be set to receive the third reference voltage V... REF1 Set the fifth reference voltage V REF2 With the third reference voltage V REF1 The voltage magnitudes are equal, and this third reference voltage V REF1 With the second reference voltage V L The difference (V) REF1 -V L The voltage V is greater than the first threshold voltage V of the first drive switch module T1. TH，T1 Therefore, at the beginning of this stage, the first drive switch module T1 is turned on, and the potential of the first node A will be determined by the second reference voltage V. L Gradually rise to (V) REF1 -V TH，T1 Until the first drive switch module T1 is turned off, at the end of this stage, the voltage stored across the first storage capacitor C1 is as follows:

[0096] V C1 =V DATA(PAM) -(V REF1 -V TH，T1 ).

[0097] (3) Second threshold compensation stage

[0098] In the second threshold compensation stage, all signals are low except the third scan signal S3 which is high, thus turning on the second compensation module T7, the pulse width modulation module T9 and the fourth reset module T12. In this stage, the second drive switch module T2 is turned on due to the second compensation module T7, and the gate and the drain of the second drive switch module T2 are connected, forming a diode-like connection. The fourth node D voltage will gradually decrease to (V REF2 +V TH，T2 ) until the second drive switch module T2 is turned off. At the same time, the pulse width modulation data voltage V DATA(PWM) is applied to the fifth node E, i.e. the second end of the second storage capacitor C2, by the pulse width modulation module T9. Thus, at the end of this stage, the voltage stored across the second storage capacitor C2 is as follows:

[0099] V C2 = V DATA(PWM) -(V REF1 +V TH，T2 )

[0100] In this stage, the second reference voltage V L is applied to the first node A, i.e. the first node A voltage is pulled down to the second reference voltage V L , by the fourth reset module T12. Due to the effect of the first storage capacitor C1, the third node C voltage is correspondingly pulled down, but the voltage stored across the first storage capacitor C1 is still as follows:

[0101] V C1 = V DATA(PAM) -(V REF1 -V TH，T1 ).

[0102] (4) The light emitting stage: all signals are low except the light emitting signal EM which is high, thus turning on the first compensation module T5 and the light emitting switch module T10. Since the first compensation module T5 is turned on, the second node B and the third node C are connected to one point, and the gate-source voltage of the first drive switch module T1 is equal to the voltage stored across the first storage capacitor C1 in the last stage. In actual use, the voltage is set to be higher than the first threshold voltage V TH，T1 of the first drive switch module T1, so the first drive switch module T1 is turned on at the beginning of this stage, and the drive current flows through the light emitting element LED to make it emit light. The first end of the light emitting element LED is the first node A, and its voltage will rise to V LED . Due to the coupling effect of the first storage capacitor C1, the voltages of the second node B and the third node C will also rise by the same value as the voltage of the first node A.

[0103] V B = V C = V C1 + V A = V DATA(PAM) - (V REF1 - V TH，T1 ) + V LED

[0104] Therefore, the gate-source voltage of the first drive switch module T1 is still equal to the voltage stored across the first storage capacitor C1 in the first threshold compensation stage:

[0105] V GS，T1 = V B - V A = V C1 = V DATA(PAM) - (V REF1 - V TH，T1 )

[0106] Therefore, the luminous current is as follows:

[0107] I LED = 0.5k(V GS，T1 - V TH，T1 ) 2 = 0.5k(V DATA(PAM) - V REF1 ) 2

[0108] where k = μCOX(W / L)T1, μ is the carrier mobility, COX is the unit area gate oxide layer capacitance, and (W / L)T1 is the width-length ratio of the first drive switch module T1. The luminous current formula does not contain V TH，T1 and V SS , so the luminous current size is irrelevant to the first threshold voltage V TH，T1 and the fourth reference voltage V SS .

[0109] As for the pulse width modulation module 31, the ramp signal is applied to the fifth node E through the light-emitting switch module T10, and the potential of the fifth node E becomes V SWEEP , and due to the coupling effect of the second storage capacitor C2, the potential of the fourth node D becomes:

[0110] V D = V E - V C2 = V SWEEP - V DATA(PWM) + (V REF1 + V TH，T2 )

[0111] V GS，T2 = VD -V REF1 =V SWEEP -V DATA(PWM) +V TH，T2

[0112] When the gate-source voltage V of the second drive switch module T2 GS，T2 >V TH，T2 At that time, the second drive switch module T2 is turned on, and the potential of the second node B is pulled down to V. REF1 When the first drive switch module T1 is turned off, the LED stops emitting light, and at this time there is V SWEEP >V DATA(PWM) Therefore, it can be seen that the duration of light emission is determined by the pulse width modulation data voltage V. DATA(PWM) The decision is made based on the second threshold voltage V. TH，T2 Irrelevant.

[0113] In this embodiment, the pixel circuit directly couples the pulse width modulation module 31 and the pulse amplitude modulation module 32, saving the coupling TFT and its control signal; the first terminal of the light-emitting element LED is the first node A, which is coupled to the second reference voltage V through the first reset module T3 and the fourth reset module T12 respectively, under the action of the first scan signal S1 and the third scan signal S3. L Therefore, the first terminal of the light-emitting element LED, the first node A, maintains a low voltage during the non-light-emitting initialization stage, the first threshold compensation stage, and the second threshold compensation stage. This suppresses the leakage current (light leakage) phenomenon of the light-emitting element LED during the non-light-emitting stage and improves the contrast of the LED display.

[0114] Based on the same inventive concept, this invention also provides a driving method for a pixel circuit, which applies the pixel circuit described in the above embodiments. Figure 9 This is a flowchart of the pixel circuit driving method according to the fourth embodiment of the present invention. Figure 9 As shown, the driving method for the pixel circuit includes:

[0115] S100, during the initialization phase, the second terminal of the first drive switch module is configured to receive the second reference voltage;

[0116] S200, in the first threshold compensation stage, the first drive switch module is turned on according to the third reference voltage, so that the voltage at the second terminal of the first drive switch module gradually approaches the third reference voltage until it differs from the first threshold voltage; and the amplitude modulation drive module provides amplitude modulation data voltage to the second terminal of the first storage capacitor.

[0117] S300, in the light-emitting stage, the first compensation module is turned on according to the light-emitting signal, the first compensation module and the first storage capacitor perform threshold compensation of the first driving switch module and write of the amplitude-modulated data voltage, so as to realize accurate modulation of the light-emitting current size in the light-emitting stage; at the same time, the pulse width modulation module controls the voltage of the control end of the first driving switch module to control the light-emitting duration.

[0118] In an embodiment of the application, the pixel circuit comprises a connection module, a first end of the connection module being connected to the pulse amplitude modulation module, a second end of the connection module being connected to the pulse width modulation module, and a control end of the connection module receiving the light-emitting signal; the driving method of the pixel circuit further comprises: before the light-emitting stage, the connection module disconnects the pulse width modulation module and the pulse amplitude modulation module, so that the pulse width modulation of the pulse width modulation module and the pulse amplitude modulation of the pulse amplitude modulation module do not interfere with each other; in the light-emitting stage, the connection module turns on the pulse width modulation module and the pulse amplitude modulation module according to the light-emitting signal.

[0119] In an embodiment, the driving method of the pixel circuit further comprises: in the second threshold compensation stage, the pulse width modulation module performs pulse width modulation, wherein the second threshold compensation stage and the first threshold compensation stage are the same time period.

[0120] In an embodiment of the application, the pulse width modulation module and the pulse amplitude modulation module are directly connected; the driving method of the pixel circuit further comprises: in the first threshold compensation stage, the pulse width modulation module provides the third reference voltage; in the second threshold compensation stage, the pulse width modulation module performs pulse width modulation, wherein the second threshold compensation stage is arranged after the first threshold compensation stage.

[0121] In an embodiment of the application, the driving method of the pixel circuit further comprises: in the second threshold compensation stage, the pulse width modulation module compensates the threshold voltage by adopting a structure similar to a diode connection, so as to realize accurate modulation of the light-emitting duration in the light-emitting stage.

[0122] The implementation of the driving method of the pixel circuit can refer to the above-described embodiments of the pixel circuit, and repeated parts will not be described herein.

[0123] Based on the same inventive concept, the embodiments of the application further provide a display device comprising the pixel circuit of any of the above-described embodiments, and the implementation of the display device can refer to the above-described embodiments of the pixel circuit, and repeated parts will not be described herein.

[0124] The pixel circuit, the driving method and the display device provided by the embodiment of the present application are characterized in that, in the initialization stage, the second end of the first driving switch module is arranged to receive the second reference voltage; before the light-emitting stage, the control end of the first driving switch module is arranged to receive the third reference voltage, the difference between the third reference voltage and the second reference voltage is greater than the first threshold voltage of the first driving switch module, and the two ends of the first storage capacitor can be respectively used for threshold compensation of the first driving switch module and writing of the amplitude-modulated data voltage, so that the voltage of the control end of the first driving switch module can be changed by the first compensation module in the light-emitting stage, threshold compensation and writing of the amplitude-modulated data voltage are realized, that is, the pulse width modulation driving method is adopted, the light-emitting element can be ensured to work at the current density with the maximum light-emitting efficiency, and the power consumption is also reduced, the pixel circuit can realize accurate modulation of the light-emitting current size in the light-emitting stage according to the amplitude-modulated data voltage, and the display quality is improved. Moreover, the light-emitting branch in the pixel circuit does not have an additional driving module except the first driving switch module, the cross voltage of the light-emitting branch is reduced, and thus the power consumption is reduced.

[0125] In addition, the second end of the second driving switch module can be arranged to receive the fifth reference voltage, and the control end of the second driving switch module can be arranged to receive the sixth reference voltage in the initialization stage, the difference between the sixth reference voltage and the fifth reference voltage is greater than the second threshold voltage of the second driving switch module; threshold compensation of the second driving switch module and writing of the width-modulated data voltage are performed by the second compensation module and the second storage capacitor, the second compensation module is arranged between the first end and the control end of the second driving switch module, and a structure similar to a diode connection is formed to realize threshold compensation; the first end of the second storage capacitor is connected with the control end of the second driving switch module, and the second end of the second storage capacitor receives the width-modulated data voltage to realize accurate modulation of the light-emitting duration in the light-emitting stage.

[0126] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as the above preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A pixel circuit, characterized in that, include: A pulse amplitude modulation module is provided, comprising a first drive switch module (T1), a first reset module (T3), a first storage capacitor (C1), a first compensation module (T5), and an amplitude modulation drive module (T6). The first terminal of the first drive switch module (T1) receives a first reference voltage, the second terminal of the first drive switch module (T1) receives a second reference voltage sent by the first reset module (T3) during the initialization phase, and the control terminal of the first drive switch module (T1) receives a third reference voltage before the emission phase. The difference between the third reference voltage and the second reference voltage is greater than the first reference voltage. The first threshold voltage of the drive switch module (T1); the first terminal of the first storage capacitor (C1) is connected to the second terminal of the first drive switch module (T1); the first terminal of the first compensation module (T5) is connected to the second terminal of the first storage capacitor (C1), the second terminal of the first compensation module (T5) is connected to the control terminal of the first drive switch module (T1), and the control terminal of the first compensation module (T5) receives the light emission signal (EM); the amplitude modulation drive module (T6) provides amplitude modulation data voltage to the second terminal of the first storage capacitor (C1) during the initialization phase and the first threshold compensation phase; A light-emitting element (LED) is provided, wherein a first end of the light-emitting element (LED) is connected to a second end of the first driving switch module (T1), and the second end of the light-emitting element (LED) receives a fourth reference voltage. A pulse width modulation module is used to control the voltage at the control terminal of the first driving switch module (T1) during the light emission stage to control the light emission duration. The pulse width modulation module includes a second drive switch module (T2), a second reset module (T8), a second storage capacitor (C2), a pulse width modulation drive module (T9), an LED switch module (T10), and a second compensation module (T7); The first terminal of the second driving switch module (T2) is used to control the voltage of the control terminal of the first driving switch module (T1) during the light emission stage. The second terminal of the second driving switch module (T2) receives a fifth reference voltage. The control terminal of the second driving switch module (T2) receives a sixth reference voltage sent by the second reset module (T8) during the initialization stage. The difference between the sixth reference voltage and the fifth reference voltage is greater than the first threshold voltage of the first driving switch module (T1). The first end of the second compensation module (T7) is connected to the first end of the second drive switch module (T2), the second end of the second compensation module (T7) is connected to the control end of the second drive switch module (T2), and the second compensation module (T7) is set to the conducting state in the second threshold compensation stage; The first terminal of the second storage capacitor (C2) is connected to the control terminal of the second drive switch module (T2); The pulse width modulation drive module (T9) is used to provide a pulse width modulation data voltage to the second terminal of the second storage capacitor (C2) during the second threshold compensation stage; The light-emitting switch module (T10) is used to provide a switch control signal to the second terminal of the second storage capacitor (C2) according to the light-emitting signal (EM) during the light-emitting stage; The first terminal of the second drive switch module (T2) is connected to the control terminal of the first drive switch module (T1). The voltages of the third reference voltage and the fifth reference voltage are equal. The first threshold compensation stage is set before the second threshold compensation stage.

2. The pixel circuit according to claim 1, characterized in that, The pulse amplitude modulation module further includes a fourth reset module (T12). The first end of the fourth reset module (T12) is connected to the second end of the first drive switch module (T1). The second end of the fourth reset module (T12) receives the second reference voltage. The fourth reset module (T12) is set to the on state during the second threshold compensation stage.

3. A driving method for a pixel circuit, characterized in that, The pixel circuit described in claim 1 is applied; The driving method for the pixel circuit includes: During the initialization phase, the second terminal of the first drive switch module (T1) is configured to receive the second reference voltage; During the first threshold compensation stage, the first drive switch module (T1) is turned on according to the third reference voltage, so that the voltage at the second terminal of the first drive switch module (T1) gradually approaches the third reference voltage until it differs from the first threshold voltage; and the amplitude modulation drive module (T6) provides the amplitude modulation data voltage to the second terminal of the first storage capacitor (C1). During the light emission stage, the first compensation module (T5) is turned on according to the light emission signal (EM). The first compensation module (T5) and the first storage capacitor (C1) perform threshold compensation of the first driving switch module (T1) and write the amplitude modulation data voltage to achieve precise modulation of the light emission current during the light emission stage. At the same time, the pulse width modulation module controls the voltage of the control terminal of the first driving switch module (T1) to control the light emission duration. The pulse width modulation module and the pulse amplitude modulation module are directly connected; the driving method further includes: During the first threshold compensation phase, the pulse width modulation module provides the third reference voltage; In the second threshold compensation stage, the pulse width modulation module performs pulse width modulation, wherein the second threshold compensation stage is set after the first threshold compensation stage.

4. A display device, characterized in that, Includes the pixel circuit described in any one of claims 1-2.

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