Pixel circuit, driving method thereof and display panel

Abstract

The invention discloses a pixel circuit, a driving method thereof and a display panel. The pixel circuit comprises a driving module, a light emitting module, a data writing module, a compensation module and a coupling module, the data writing module is connected with a first end of the coupling module, a second end of the coupling module is connected with a first end of the driving module, and the data writing module is used for writing a first voltage into the first end of the coupling module and is also used for writing a data voltage into the first end of the coupling module; the coupling module is used for coupling the data voltage to the control end of the driving module; the first end of the compensation module is connected with the first end of the driving module, the second end of the compensation module is connected with the control end of the driving module, and the compensation module is used for writing the threshold voltage of the driving module into the control end of the driving module, so that the threshold compensation of the driving module is realized, the circuit structure is simplified, and the screen body transmittance and resolution are improved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a pixel circuit and a driving method thereof, and a display panel. Background Art

[0002] An active matrix organic light emitting diode display device emits light by current drive. The display device includes a plurality of sub-pixels, each of which includes a pixel circuit. A driving transistor in the pixel circuit generates a driving current to drive the sub-pixel to emit light. Therefore, the electrical properties of the driving transistor directly affect the grayscale brightness difference of the display device. When the electrical properties of the driving transistors in different sub-pixels differ too much, it is easy to cause uneven image quality, such as uneven display brightness.

[0003] The existing pixel circuits that can improve display unevenness have a complex structure and contain many transistors, which is not conducive to improving the transmittance and resolution of the screen. Summary of the invention

[0004] The present invention provides a pixel circuit and a driving method thereof, and a display panel, so as to simplify the circuit structure and improve the screen transmittance and resolution while realizing threshold compensation of a driving module.

[0005] According to one aspect of the present invention, there is provided a pixel circuit, comprising: a driving module, a light emitting module, a data writing module, a compensation module and a coupling module;

[0006] The driving module and the light-emitting module are connected in series between a first power source and a second power source, and the driving module is used to generate a driving current according to the potential of the control terminal of the driving module to drive the light-emitting module to emit light;

[0007] The data writing module is connected to the first end of the coupling module, the second end of the coupling module is connected to the first end of the driving module, the data writing module is used to write the first voltage into the first end of the coupling module, and is also used to write the data voltage into the first end of the coupling module;

[0008] The coupling module is used to couple the data voltage to the control terminal of the driving module;

[0009] The first end of the compensation module is connected to the first end of the driving module, the second end of the compensation module is connected to the control end of the driving module, and the compensation module is used to write the threshold voltage of the driving module into the control end of the driving module.

[0010] Optionally, the pixel circuit further includes a storage module, which is connected to the control terminal of the driving module and is used to store the threshold voltage of the driving module;

[0011] Optionally, the control end of the compensation module is connected to the second scanning signal, and the control end of the data writing module is connected to the first scanning signal;

[0012] The compensation module is used to respond to the second scanning signal and write the threshold voltage of the driving module into the control terminal of the driving module in the compensation stage; the data writing module is used to respond to the first scanning signal and write the first voltage into the first terminal of the coupling module in the compensation stage, and is also used to write the data voltage into the first terminal of the coupling module in the data writing stage; the driving module is used to generate a driving current according to the potential of the control terminal of the driving module in the light-emitting stage to drive the light-emitting module to emit light;

[0013] Optionally, the driving module includes a first transistor, the compensation module includes a second transistor, the data writing module includes a third transistor, the coupling module includes a first capacitor, and the storage module includes a second capacitor;

[0014] The first end of the light emitting module is connected to the first power source, and the second end of the light emitting module is connected to the first electrode of the first transistor;

[0015] The second electrode of the first transistor is connected to the second power supply;

[0016] A first electrode of the third transistor is connected to the data line, a second electrode of the third transistor is connected to the first end of the first capacitor, and a gate of the third transistor is connected to the first scanning signal;

[0017] The second end of the first capacitor is connected to the first electrode of the first transistor;

[0018] The first electrode of the second transistor is connected to the first electrode of the first transistor, the second electrode of the second transistor is connected to the gate of the first transistor, and the gate of the second transistor is connected to the second scanning signal;

[0019] A first end of the second capacitor is connected to the gate of the first transistor, and a second end of the second capacitor is connected to the second electrode of the first transistor;

[0020] Optionally, the first transistor is an N-type transistor

[0021] Optionally, the first transistor is an oxide transistor;

[0022] Optionally, the second transistor and the third transistor are both N-type transistors;

[0023] Optionally, the second transistor and the third transistor are both oxide transistors.

[0024] Optionally, the data writing module is further used to write the second voltage into the first end of the coupling module in a first initialization phase; wherein the first initialization phase is before the compensation phase;

[0025] The second voltage is less than the first voltage;

[0026] Optionally, the second power supply is used to output a third voltage in the first initialization stage, so that the voltage difference across the light emitting module is smaller than a start-up voltage of the light emitting module.

[0027] Optionally, the pixel circuit further includes a light emitting control module;

[0028] The light emitting module, the light emitting control module and the driving module are sequentially connected in series between the first power source and the second power source;

[0029] The control end of the light emitting control module is connected to the first scanning signal;

[0030] Optionally, the light emitting control module includes a fourth transistor, a first end of the light emitting module is connected to the first power supply, a first electrode of the fourth transistor is connected to the second end of the light emitting module, a second electrode of the fourth transistor is connected to the first electrode of the first transistor, and a gate of the fourth transistor is connected to the first scanning signal;

[0031] Optionally, the fourth transistor is a P-type transistor;

[0032] Optionally, the fourth transistor is a low-temperature polysilicon transistor.

[0033] Optionally, the pixel circuit further includes an initialization module, the initialization module is connected to a common node, the common node is a node to which the light emitting module and the light emitting control module are connected, and the initialization module is used to transmit the voltage output by the first power supply to the common node in the second initialization stage;

[0034] Optionally, the control end of the initialization module receives the second scanning signal, and the second initialization phase includes the compensation phase and the data writing phase;

[0035] Optionally, the initialization module includes a fifth transistor, a first electrode of the fifth transistor is connected to the first power supply, a second electrode of the fifth transistor is connected to the common node, and a gate of the fifth transistor is connected to the second scanning signal;

[0036] Optionally, the fifth transistor is an N-type transistor;

[0037] Optionally, the fifth transistor is an oxide transistor.

[0038] Optionally, the first power supply is a DC power supply, and the second power supply is an AC power supply;

[0039] Optionally, the second power supply is used to output a third voltage in the compensation stage and the data writing stage so that the voltage difference across the light-emitting module is smaller than the start-up voltage of the light-emitting module, and is also used to output a fourth voltage in the light-emitting stage so that the voltage difference across the light-emitting module is larger than the start-up voltage of the light-emitting module, and the third voltage is larger than the fourth voltage.

[0040] Optionally, the second power supply is generated by a scan driver.

[0041] According to another aspect of the present invention, a driving method of a pixel circuit is provided, wherein the pixel circuit comprises a driving module, a light emitting module, a data writing module, a compensation module and a coupling module; the driving module and the light emitting module are connected in series between a first power supply and a second power supply, the data writing module is connected to a first end of the coupling module, the second end of the coupling module is connected to a first end of the driving module, the first end of the compensation module is connected to a first end of the driving module, and the second end of the compensation module is connected to a control end of the driving module;

[0042] The driving method of the pixel circuit comprises:

[0043] In the compensation stage, the data writing module is controlled to be turned on to write the first voltage into the first end of the coupling module, and the compensation module is controlled to be turned on to write the threshold voltage of the driving module into the control end of the driving module;

[0044] In the data writing stage, the data writing module and the compensation module are controlled to be turned on to write the data voltage into the first end of the coupling module, and the data voltage is coupled to the control end of the driving module through the compensation module via the coupling module;

[0045] In the light-emitting stage, the driving module generates a driving current according to the potential of the control terminal of the driving module to drive the light-emitting module to emit light.

[0046] Optionally, the pixel circuit further includes a storage module, and the storage module is connected to the control end of the driving module;

[0047] The driving method of the pixel circuit further includes:

[0048] In the first initialization phase:

[0049] Controlling the data writing module to be turned on to write the second voltage into the first end of the coupling module;

[0050] Controlling the second power supply to output a third voltage, so that under the action of the storage module, the driving module is turned on, and the voltage difference across the light-emitting module is smaller than the start-up voltage of the light-emitting module;

[0051] The first initialization phase is located before the compensation phase.

[0052] According to another aspect of the present invention, a display panel is provided, comprising the pixel circuit described in the first aspect.

[0053] In the pixel circuit of the embodiment of the present invention, when threshold compensation is performed on the driving module, the driving module is turned on, and the control end of the driving module charges the second end of the driving module through the compensation module, and then the threshold voltage of the driving module is written into the control end of the driving module, so as to compensate for the threshold voltage of the driving module, thereby improving the uniformity of the screen display. At the same time, the pixel circuit only includes the driving module, the data writing module, the compensation module and the coupling module, and has a simple structure, a small number of modules included, and a simplified circuit structure, which is conducive to improving the screen transmittance and resolution.

[0054] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 A schematic structural diagram of a pixel circuit provided by an embodiment of the present invention;

[0057] Figure 2 A schematic structural diagram of another pixel circuit provided by an embodiment of the present invention;

[0058] Figure 3 A schematic structural diagram of another pixel circuit provided by an embodiment of the present invention;

[0059] Figure 4 A driving timing diagram of a pixel circuit provided by an embodiment of the present invention;

[0060] Figure 5 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0061] Figure 6A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0062] Figure 7 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0063] Figure 8 A schematic diagram of another pixel circuit provided by an embodiment of the present invention;

[0064] Fig. 9 A flowchart of a driving method of a pixel circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0066] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0067] As described in the background technology, the existing pixel circuits that can improve the uneven display have a complex structure. In the prior art, a 7T1C circuit is generally used to realize the compensation of the threshold voltage of the driving module. The 7T1C pixel circuit includes 7 transistors and a storage capacitor, for example, including a data writing transistor, a driving transistor, a compensation transistor, a first initialization transistor, a second initialization transistor, a first light-emitting control transistor, a second light-emitting control transistor and a storage capacitor. In the data writing and threshold compensation stage, the existing 7T1C pixel circuit writes a voltage related to the data voltage and the threshold voltage of the driving transistor into the gate of the driving transistor through the data writing transistor and the compensation transistor to realize threshold compensation. The existing pixel circuit includes a large number of transistors, and the layout of the display panel is complex, and it is impossible to achieve higher resolution and transmittance.

[0068] In view of the above technical problems, an embodiment of the present invention provides a novel pixel circuit to simplify the circuit structure and improve the transmittance and resolution of the screen while realizing threshold compensation of the driving module.

[0069] Figure 1 A schematic diagram of a pixel circuit according to an embodiment of the present invention is provided. Figure 1 , the pixel circuit includes: a driving module 10, a light emitting module 11, a data writing module 12, a compensation module 13 and a coupling module 14;

[0070] The driving module 10 and the light emitting module 11 are connected in series between a first power source VDD and a second power source VSS. The driving module 10 is used to generate a driving current according to the potential of the control terminal of the driving module 10 to drive the light emitting module 11 to emit light.

[0071] The data writing module 12 is connected to the first end of the coupling module 14, and the second end of the coupling module 14 is connected to the first end of the driving module 10. The data writing module 12 is used to write the first voltage into the first end of the coupling module 14, and is also used to write the data voltage Vdata into the first end of the coupling module 14;

[0072] The coupling module 14 is used to couple the data voltage Vdata to the control end of the driving module 10 via the compensation module 13;

[0073] A first end of the compensation module 13 is connected to a first end of the driving module 10 , and a second end of the compensation module 13 is connected to a control end of the driving module 10 . The compensation module 13 is used to write the threshold voltage of the driving module 10 into the control end of the driving module 10 .

[0074] The light-emitting module 11 includes a light-emitting device, which may be an organic light-emitting device or an inorganic light-emitting device. This embodiment does not specifically limit this. Exemplarily, the light-emitting device is an OLED device. A first end of the light-emitting module 11 is connected to a first power source VDD, and a second end of the light-emitting module 11 is connected to a first end of the driving module 10. The first end of the light-emitting module 11 may be an anode of the light-emitting device, and the second end of the light-emitting module 11 may be a cathode of the light-emitting device.

[0075] The data writing module 12 and the compensation module 13 are switch modules, which connect the two ends of the modules after being turned on. Taking the compensation module 13 as an example, after the compensation module 13 is turned on, the first end of the driving module 10 and the control end of the driving module 10 are connected, so that the control end and the first end of the driving module 10 are connected, and the driving module 10 becomes a diode connection mode. The driving module 10 includes a transistor, and the threshold voltage of the driving module 10 is the threshold voltage of the transistor included in the driving module 10.

[0076] Optionally, the working process of the pixel circuit includes: a compensation stage, a data writing stage and a light emitting stage. In the compensation stage, the data writing module 12 is turned on in response to the signal connected to its control end, and the compensation module 13 is turned on in response to the signal connected to its control end, and the turned-on data writing module 12 writes the first voltage to the first end of the coupling module 14. The first voltage is a relatively high voltage, and the potential of the first end of the coupling module 14 is raised. Under the action of capacitive coupling, the potential of the second end of the coupling module 14 is also raised, thereby turning on the driving module 10, and the current flows from the control end of the driving module 10 through the compensation module 13 and the driving module 10 to the second power supply VSS, until the potential Vg of the control end of the driving module 10 is V0+Vth, the driving module 10 is turned off, and the threshold voltage of the driving module 10 is written to the control end of the driving module 10. Among them, V0 is the voltage output by the second power supply VSS in the compensation stage, and Vth is the threshold voltage of the driving module 10.

[0077] In the data writing stage, the data writing module 12 is turned on in response to the signal connected to its control end, and the compensation module 13 is turned on in response to the signal connected to its control end. The turned-on data writing module 12 writes the data voltage Vdata into the first end of the coupling module 14. Under the coupling action of the coupling module 14, the data voltage Vdata is written into the control end of the driving module through the compensation module 13, so that in the data writing stage, the control end of the driving module 10 is a potential related to the threshold voltage and the data voltage.

[0078] In the light-emitting stage, the data writing module 12 is turned off in response to the signal received by its control terminal, and the compensation module 13 is turned off in response to the signal received by its control terminal. The driving module 10 is used to generate a driving current I according to the potential of the control terminal of the driving module 10 in the light-emitting stage to drive the light-emitting module 11 to emit light. Driving current I = k*(Vg-Vs-Vth) 2 ; k is a parameter related to the structure of the light-emitting device. After the light-emitting device is prepared, k is a constant. Vs is the voltage at the second end of the driving module 10. Since the voltage at the control end of the driving module 10 is a potential related to the threshold voltage and the data voltage, after subtracting the threshold voltage, the magnitude of the driving current is independent of the threshold voltage, which compensates for the discreteness of the threshold voltage of the driving module and improves the uniformity of the screen display.

[0079] In the pixel circuit of the embodiment of the present invention, when compensating the threshold voltage of the driving module, the driving module is turned on, the control end of the driving module charges the second end of the driving module through the compensation module, and then the threshold voltage is written into the control end of the driving module, and the threshold voltage of the driving module is compensated by diode compensation, thereby improving the uniformity of the screen display. At the same time, the pixel circuit only includes the driving module, the data writing module, the compensation module and the coupling module, the structure is simple, the number of modules included is small, the circuit structure is simplified, and it is conducive to improving the screen transmittance and resolution.

[0080] Figure 2 This is a schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention. Based on the above embodiment, optionally, the pixel circuit further includes a storage module 15, the storage module 15 is connected to the control end of the driving module 10, and the storage module 15 is used to store the threshold voltage of the driving module 10. Further, the storage module 15 is connected between the control end of the driving module 10 and the first end of the driving module.

[0081] Optionally, the control end of the compensation module 13 is connected to the second scanning signal S2, and the compensation module 13 is turned on in response to the effective potential of the second scanning signal S2, and is turned off in response to the invalid potential of the second scanning signal S2. The effective potential of the second scanning signal S2 is the potential for controlling the compensation module 13 to be turned on, and the invalid potential of the second scanning signal S2 is the potential for controlling the compensation module 13 to be turned off. The compensation module 13 is used to respond to the second scanning signal and write the threshold voltage of the driving module 10 to the control end of the driving module 10 in the compensation stage.

[0082] The control end of the data writing module 12 is connected to the first scanning signal S1. The data writing module 12 is turned on in response to the effective potential of the first scanning signal S1 and is turned off in response to the invalid potential of the first scanning signal S1. The effective potential of the first scanning signal S1 is the potential for controlling the data writing module 12 to be turned on, and the invalid potential of the first scanning signal S1 is the potential for controlling the data writing module 12 to be turned off. The data writing module 12 is used to respond to the first scanning signal S1, write the first voltage to the first end of the coupling module 14 in the compensation phase, and also to write the data voltage to the first end of the coupling module 14 in the data writing phase.

[0083] Based on the above embodiments, the embodiments of the present invention provide a specific pixel circuit structure, such as Figure 3 shown. Figure 3 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention, Figure 3 Can be Figure 2 An optional circuit structure is shown in Figure 2 and Figure 3Optionally, the driving module 10 includes a first transistor T1, the compensation module 13 includes a second transistor T2, the data writing module 12 includes a third transistor T3, the coupling module 14 includes a first capacitor C1, and the storage module 15 includes a second capacitor C2;

[0084] A first end of the light emitting module 11 is connected to a first power source VDD, and a second end of the light emitting module 11 is connected to a first electrode of a first transistor T1;

[0085] The second electrode of the first transistor T1 is connected to the second power supply VSS;

[0086] A first electrode of the third transistor T3 is connected to the data line, a second electrode of the third transistor T3 is connected to the first end of the first capacitor C1, and a gate of the third transistor T3 is connected to the first scanning signal S1;

[0087] The second end of the first capacitor C1 is connected to the first electrode of the first transistor T1;

[0088] A first electrode of the second transistor T2 is connected to a first electrode of the first transistor T1, a second electrode of the second transistor T2 is connected to a gate of the first transistor T1, and a gate of the second transistor T2 is connected to a second scanning signal S2;

[0089] A first end of the second capacitor C2 is connected to the gate of the first transistor T1 , and a second end of the second capacitor C2 is connected to the second electrode of the first transistor T1 .

[0090] The first transistor T1 is an N-type transistor, the second transistor T2 can be an N-type transistor or a P-type transistor, and the third transistor T3 can be an N-type transistor or a P-type transistor. When the second transistor T2 is an N-type transistor, the effective potential of the second scan signal S2 is a high level and the invalid potential is a low level. When the second transistor T2 is a P-type transistor, the effective potential of the second scan signal S2 is a low level and the invalid potential is a high level. When the third transistor T3 is an N-type transistor, the effective potential of the first scan signal S1 is a high level and the invalid potential is a low level. When the third transistor T3 is a P-type transistor, the effective potential of the first scan signal S1 is a low level and the invalid potential is a high level. Optionally, the first transistor T1, the second transistor T2 and the third transistor T3 are all N-type transistors, and further, the first transistor T1, the second transistor T2 and the third transistor T3 are all oxide transistors to reduce leakage current.

[0091] Figure 4 A driving timing diagram of a pixel circuit provided by an embodiment of the present invention, Figure 4 The drive timing shown is applicable to Figure 2 and Figure 3In the pixel circuit shown in the embodiment, the first transistor T1, the second transistor T2 and the third transistor T3 are all N-type transistors. The working process of the pixel circuit is as follows:

[0092] In the first initialization stage t1, the first scanning signal S1 is at a high level, the second scanning signal S2 is at a low level, the compensation module 13 (the second transistor T2) is turned off in response to the low level of the second scanning signal S2, and the data writing module 12 (the third transistor T3) is turned on in response to the high level of the first scanning signal S1. The data writing module 12 is also used to write the second voltage Vref_L to the first end of the coupling module 14 in the first initialization stage t1. That is, before writing the first voltage Vref_H, the data writing module 12 is also used to write the second voltage Vref_L to the first end of the coupling module 14. In the first initialization stage t1, the voltage transmitted by the data line is the second voltage Vref_L, and the turned-on data writing module 12 (the third transistor T3) transmits the second voltage Vref_L to the first end of the coupling module 14 (the first capacitor C1), and the second voltage Vref_L is less than the corresponding data voltage under any gray scale. Since the potential of the first end of the coupling module 14 (first capacitor C1) is the data voltage of the previous screen at the previous moment, the potential of the first end of the coupling module 14 (first capacitor C1) becomes the second voltage Vref_L, and the potential of the first end of the coupling module 14 (first capacitor C1) decreases. Due to the effect of capacitive coupling, the potential of the second end of the coupling module 14 (first capacitor C1) also decreases. The second power supply VSS is used to output the third voltage VSS_H in the first initialization stage t1, so that the voltage difference between the two ends of the light-emitting module 11 is less than the start-up voltage of the light-emitting module 11. Because at the last moment, the second power supply VSS outputs the fourth voltage VSS_L, which is less than the third voltage VSS_H, therefore, after the voltage output by the second power supply VSS becomes the third voltage VSS_H, the potential of the second end of the driving module 10 (the second electrode of the first transistor T1) is raised, and under the coupling effect of the storage module 15, the potential of the control end of the driving module 10 (the gate of the first transistor T1) is also raised, thereby turning on the driving module 10 (the first transistor T1), and the potential of the first end of the driving module 10 (the first electrode of the first transistor T1) is equal to the third voltage VSS_H, and the voltage difference between the two ends of the light-emitting module 11 is less than the start-up voltage of the light-emitting module 11, and the light-emitting module 11 will not be lit, thereby preventing the light-emitting module 11 from being mistakenly lit in the first initialization stage t1. Among them, the start-up voltage is the minimum value of the voltage difference between the first end and the second end of the light-emitting module 11 when it can be lit, and the minimum value of the voltage difference between the anode and the cathode. Optionally, the fourth voltage VSS_L and the start-up voltage of the light emitting module 11 are both lower than the third voltage VSS_H. Furthermore, the third voltage VSS_H is greater than 0, and the fourth voltage VSS_L is lower than 0. The first initialization stage t1 is located before the compensation stage t2 described below.

[0093] The data line transmits the first voltage Vref_H, the second voltage Vref_L and the data voltage Vdata to the pixel circuit in a time-sharing manner. The initialization voltage and the data voltage share a common wiring, which can save the number of signal wirings in the display area and improve the screen transmittance and resolution.

[0094] In the compensation stage t2, the first scanning signal S1 is at a high level, the second scanning signal S2 is at a high level, the compensation module 13 (the second transistor T2) is turned on in response to the high level of the second scanning signal S2, and the data writing module 12 (the third transistor T3) is turned on in response to the high level of the first scanning signal S1. The second power supply VSS is used to output the third voltage VSS_H in the compensation stage t2. In the compensation stage t2, the voltage transmitted by the data line is the first voltage Vref_H, the first voltage Vref_H is greater than the second voltage Vref_L, the turned-on data writing module 12 (the third transistor T3) transmits the first voltage Vref_H to the first end of the coupling module 14 (the first capacitor C1), under the coupling effect of the coupling module 14 (the first capacitor C1), the potential of the first end of the driving module 10 (the first electrode of the first transistor T1) is raised, and the potential Vd of the first end of the driving module 10 is equal to the potential Vg of the control end, so the potential Vg of the control end of the driving module 10>VSS_H, and the driving module 10 (the first transistor T1) is turned on. After the driving module 10 (the first transistor T1) is turned on, the current flows from the control end of the driving module 10 (the gate of the first transistor T1) through the compensation module 13 (the second transistor T2) and the driving module 10 (the first transistor T1) to the second power supply VSS, and discharges the storage module 15 (the second capacitor C2) until the potential Vg=Vd=VSS_H+Vth of the control end of the driving module 10 (the gate of the first transistor T1), and the driving module 10 (the first transistor T1) is turned off.

[0095] In the data writing stage t3, the first scanning signal S1 is at a high level, the second scanning signal S2 is at a high level, the compensation module 13 (the second transistor T2) is turned on in response to the high level of the second scanning signal S2, and the data writing module 12 (the third transistor T3) is turned on in response to the high level of the first scanning signal S1. The second power supply VSS is used to output the third voltage VSS_H in the data writing stage t3. The turned-on data writing module 12 (the third transistor T3) writes the data voltage Vdata transmitted by the data line into the first end of the coupling module 14 (the first end of the first capacitor C1), and the data voltage Vdata is greater than the first voltage Vref_H. Due to the coupling effect of the coupling module 14 (the first capacitor C1), the voltages of the first end of the driving module 10 (the first electrode of the first transistor T1) and the control end (the gate of the first transistor T1) are raised, and the potential Vg of the control end of the driving module 10 is Vd=VSS_H+Vth+C10 / (C10+C20)*(Vdata-Vref_H), wherein C10 is the capacitance value of the first capacitor C1 included in the coupling module 14, and C20 is the capacitance value of the second capacitor C2 included in the storage module 15. In the light-emitting stage t4, the first scanning signal S1 is at a low level, the second scanning signal S2 is at a low level, the compensation module 13 (the second transistor T2) is turned off in response to the low level of the second scanning signal S2, and the data writing module 12 (the third transistor T3) is turned off in response to the low level of the first scanning signal S1. The second power supply VSS is used to output the fourth voltage VSS_L in the light-emitting stage t4, and the third voltage VSS_H is greater than the fourth voltage VSS_L. Under the coupling effect of the storage module 15 (the second capacitor C2), Vg=VSS_L+Vth+C10 / (C10+C20)*(Vdata-Vref_H). The driving current I generated by the driving module 10=1 / 2*μ*Cox*W / L*(C10 / (C10+C20)*(Vdata-Vref_H)) 2 , where μ is the electron mobility, Cox is the channel capacitance per unit area, and W / L is the width-to-length ratio. The driving current finally generated by the driving module 10 is independent of the threshold voltage of the driving module 10, that is, the first transistor T1, thereby compensating for the discreteness of the threshold voltage of the first transistor T1 and improving display uniformity.

[0096] During the entire operation of the pixel circuit, the first power supply VDD is a DC power supply, and the output voltage remains unchanged. The second power supply VSS is an AC power supply, which is used to output a third voltage VSS_H in the first initialization stage t1, the compensation stage t2 and the data writing stage t3, so that the voltage difference across the light-emitting module 11 is less than the start-up voltage of the light-emitting module 11, to avoid the light-emitting module 11 from erroneously emitting light, and output a fourth voltage VSS_L in the light-emitting stage t4, so that the voltage difference across the light-emitting module 11 is greater than the start-up voltage of the light-emitting module 11, to ensure that the light-emitting module 11 can emit light. The second power supply is an AC signal, and fewer signal lines are set, which can improve the screen transmittance and resolution. The second power supply VSS is generated by a scanning driver, which includes a plurality of cascade-connected shift registers, the output end of the upper shift register is connected to the input end of the next shift register, and the output end of each shift register is connected to at least one row of sub-pixels, which is used to output the second power supply to the connected sub-pixels. In this embodiment, the first scanning signal S1 is generated by a group of scanning drivers, the second scanning signal S2 is generated by a group of scanning drivers, and the second power supply VSS is generated by a group of scanning drivers, so that each row of sub-pixels is lit up row by row. The display panel requires a total of three groups of scanning drivers, and the structure is simple.

[0097] In this embodiment, since the anode of the light-emitting module is directly connected to the first power source, each sub-pixel shares a common anode, and the first power source VDD can be formed by vapor deposition of the entire layer, and there is no need to set a wiring for transmitting the first power source in the display area, thereby reducing the number of signal wirings. There are only data lines and signal wiring for transmitting the second power source VSS in the display area, and there are fewer signal wirings. The pixel circuit is a 3T2C structure, including three transistors and two capacitors, and the layout is simple, which is conducive to improving the transmittance and resolution of the screen.

[0098] Figure 5 A schematic diagram of another pixel circuit provided in an embodiment of the present invention. Figure 5 , Optionally, the pixel circuit further includes a light emitting control module 16;

[0099] The light emitting module 11, the light emitting control module 16 and the driving module 10 are sequentially connected in series between the first power source VDD and the second power source VSS;

[0100] The control terminal of the light emitting control module 16 receives the first scanning signal S1 .

[0101] The first end of the light emitting module 11 is connected to the first power source VDD, the second end of the light emitting module 11 is connected to the first end of the light emitting control module 16, the second end of the light emitting control module 16 is connected to the first end of the driving module 10, and the second end of the driving module 10 is connected to the second power source VSS. The light emitting control module 16 is a switch module, which connects the two ends after being turned on. The light emitting control module 16 is used to be turned off in the first initialization stage, the compensation stage and the data writing stage under the control of the first scanning signal S1 to prevent the light emitting module 11 from being lit in the non-light emitting stage, and is also used to be turned on in the light emitting stage so that the light emitting module 11 emits light under the drive of the driving current.

[0102] This embodiment provides a Figure 5 The specific structure of the pixel circuit shown in FIG. Figure 6 shown. Figure 6 A schematic diagram of another pixel circuit provided by an embodiment of the present invention, referring to Figure 5 and Figure 6 Optionally, the light-emitting control module 16 includes a fourth transistor T4, a first end of the light-emitting module 11 is connected to the first power supply VDD, a first electrode of the fourth transistor T4 is connected to the second end of the light-emitting module 11, a second electrode of the fourth transistor T4 is connected to the first electrode of the first transistor T1, and a gate of the fourth transistor T4 is connected to the first scanning signal S1.

[0103] Optionally, the fourth transistor T4 is a P-type transistor, and further, a low-temperature polysilicon transistor. The parasitic capacitance of the low-temperature polysilicon transistor is small, which can reduce the power consumption of the screen. The fourth transistor T4 is a P-type transistor, and the signal connected to its control end is the same as the signal connected to the control end of the data writing module 12, thereby saving the number of signal sources and simplifying the screen structure.

[0104] Figure 5 and Figure 6 The timing diagram of the pixel circuit shown can be found in Figure 4 The light control module 16 is turned off in response to the high level of the first scanning signal S1 in the first initialization stage t1, the compensation stage t2 and the data writing stage t3, and is turned on in response to the low level of the first scanning signal S1 in the light emitting stage t4, so that the driving current generated by the driving module 10 drives the light emitting module 11 to emit light. The rest of the working process is the same as Figure 2 or Figure 3 The working process of the pixel circuit is the same and will not be repeated here.

[0105] Based on the above embodiment, a pixel circuit is provided. Figure 7 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention, Figure 7 The timing diagram of the pixel circuit shown can be referred to Figure 4 ,refer to Figure 3and Figure 7 Optionally, the pixel circuit also includes an initialization module 17, which is connected to a common node N. The common node N is a node where the light-emitting module 11 and the light-emitting control module 16 are connected, i.e., the second end of the light-emitting module 11. The initialization module 17 is used to transmit the voltage output by the first power supply VDD to the common node N in the second initialization stage t5.

[0106] The first end of the initialization module 17 is connected to the first power supply VDD, and the second end of the initialization module 17 is connected to the common node N. The initialization module 17 is a switch module, which connects the two ends after being turned on. The initialization module 17 is used to respond to the signal connected to the control end of the initialization module 17 in the second initialization stage t5, transmit the voltage output by the first power supply VDD to the second end of the light-emitting module 11, reset the cathode of the light-emitting module 11, and improve the residual image. Optionally, the control end of the initialization module 17 is connected to the second scanning signal S2, and the signal connected to the control end of the initialization module 17 is the same as the signal connected to the control end of the compensation module 13, which can save the number of signal sources and simplify the screen structure. If the control end of the initialization module 17 is connected to the second scanning signal S2, the second initialization stage t5 includes the compensation stage t2 and the data writing stage t3, and the initialization module 17 is used to respond to the potential conduction of the second scanning signal S2 in the compensation stage t2 and the data writing stage t3 to write the voltage of the first power supply VDD to the second end of the light-emitting module 11.

[0107] Figure 8 A schematic diagram of another pixel circuit provided by an embodiment of the present invention, Figure 8 for Figure 7 A specific structure of Figure 7 and Figure 8 Optionally, the initialization module 17 includes a fifth transistor T5, a first electrode of the fifth transistor T5 is connected to the first power supply VDD, a second electrode of the fifth transistor T5 is connected to the common node N, and a gate of the fifth transistor T5 is connected to the second scanning signal S2. The fifth transistor T5 is an N-type transistor, and further, the fifth transistor T5 is an oxide transistor to reduce leakage current.

[0108] Figure 7 and Figure 8 The pixel circuit shown is Figure 5 or Figure 6 The difference between the pixel circuit shown is that in the compensation stage t2 and the data writing stage t3, the initialization module 17 (fifth transistor T5) is turned on in response to the high level of the second scanning signal S2, and the voltage output by the first power supply VDD is transmitted to the second end of the light emitting module 11, and in the first initialization stage t1 and the light emitting stage t4, the initialization module 17 (fifth transistor T5) is turned off in response to the low level of the second scanning signal S2. Other working processes are not repeated here.

[0109] The embodiment of the present invention further provides a driving method of a pixel circuit. Fig. 9 A flowchart of a driving method of a pixel circuit provided by an embodiment of the present invention, referring to Figure 1 and Fig. 9 Optionally, the pixel circuit includes a driving module 10, a light-emitting module 11, a data writing module 12, a compensation module 13 and a coupling module 14; the driving module 10 and the light-emitting module 11 are connected in series between a first power supply VDD and a second power supply VSS, the data writing module 12 is connected to a first end of the coupling module 14, the second end of the coupling module 14 is connected to a first end of the driving module 10, the first end of the compensation module 13 is connected to a first end of the driving module 10, and the second end of the compensation module 13 is connected to a control end of the driving module 10.

[0110] The driving method of the pixel circuit includes:

[0111] S110 : in the compensation phase, the data writing module 12 is controlled to be turned on to write the first voltage Vref_H into the first end of the coupling module 14 , and the compensation module 13 is controlled to be turned on to write the threshold voltage of the driving module 10 into the control end of the driving module 10 .

[0112] The first voltage Vref_H is a relatively high voltage, which raises the potential of the first end of the coupling module 14. Under the coupling effect, the potential of the second end of the coupling module 14 is also raised. After the compensation module 13 is turned on, the control end of the driving module 10 is connected to the first end of the driving module 10, so the potential of the control end of the driving module 10 is raised, and the driving module 10 is turned on. After the driving module 10 is turned on, the current flows from the control end of the driving module 10 to the second power supply VSS through the compensation module 13 and the driving module 10 in sequence, until the potential of the control end of the driving module 10 is equal to the sum of the potential of the second end of the driving module 10 and the threshold voltage, the driving module 10 is turned off, and then the threshold voltage is written into the control end of the driving module 10.

[0113] S120 : In the data writing stage, the data writing module 12 and the compensation module 13 are controlled to be turned on to write the data voltage Vdata into the first end of the coupling module 14 , and the data voltage Vdata is coupled to the control end of the driving module 10 through the compensation module 13 via the coupling module 14 .

[0114] After the control data writing module 12 is turned on, the turned-on data writing module 12 writes the data voltage Vdata into the first end of the coupling module 14. Under the coupling action of the coupling module 14, the data voltage Vdata is coupled to the control end of the driving module 10 through the turned-on compensation module 13, thereby completing the writing of the data voltage Vdata.

[0115] S130 : In the light-emitting stage, the driving module 10 generates a driving current according to the potential of the control terminal of the driving module 10 to drive the light-emitting module 11 to emit light.

[0116] Driving current I = k*(Vg-Vs-Vth) 2 ; k is a parameter related to the structure of the light-emitting device. After the light-emitting device is prepared, k is a constant. Vs is the voltage at the second end of the driving module 10. Since the voltage at the control end of the driving module 10 is a potential related to the threshold voltage and the data voltage, after subtracting the threshold voltage, the magnitude of the driving current is independent of the threshold voltage, which compensates for the discreteness of the threshold voltage of the driving module and improves the uniformity of the screen display.

[0117] In the driving method of the pixel circuit of an embodiment of the present invention, in the compensation stage, the driving module is turned on, the control end of the driving module charges the second end of the driving module through the compensation module, and then the threshold voltage is written into the control end of the driving module to achieve compensation for the threshold voltage of the driving module, thereby improving the uniformity of the screen display.

[0118] Optionally, the pixel circuit further includes a storage module 15, and the storage module 15 is connected to the control end of the driving module 10, and before S110, the following steps are further included:

[0119] In the first initialization stage, the data writing module 12 is controlled to be turned on to write the second voltage Vref_L into the first end of the coupling module 14; the second voltage Vref_L is less than the first voltage Vref_H; the first initialization stage is before the compensation stage.

[0120] The second power source VSS is controlled to output a third voltage, so that the driving module 10 is turned on under the action of the storage module 15, and the voltage difference across the light-emitting module is smaller than the start-up voltage of the light-emitting module.

[0121] The second voltage Vref_L is a relatively low potential, which is less than the data voltage under any gray scale. At the last moment of the first initialization stage, the potential of the first end of the coupling module 14 is the data voltage of the last frame. Therefore, in the first initialization stage, after the turned-on data writing module 12 writes the second voltage Vref_L into the first end of the coupling module 14, the potential of the first end of the coupling module 14 decreases. Under the coupling effect, the potential of the first end of the driving module 10 decreases. In the first initialization stage, the second power supply VSS outputs the third voltage VSS_H. Under the coupling effect of the storage module 15, the potential of the control end of the driving module 10 is raised, the driving module 10 is turned on, and the potential of the first end of the driving module 1 is the third voltage VSS_H. When the second power supply VSS outputs the third voltage VSS_H, the voltage difference between the two ends of the light-emitting module 11 is less than the start-up voltage of the light-emitting module 11, so as to prevent the light-emitting module 10 from being mistakenly lit.

[0122] An embodiment of the present invention further provides a display panel, comprising the pixel circuit in any of the above embodiments. The beneficial effects of the display panel are the same as those of the pixel circuit, which will not be described in detail herein.

[0123] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0124] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pixel circuit, characterized in that: include: Driving module, light emitting module, data writing module, compensation module and coupling module; The driving module and the light-emitting module are connected in series between a first power source and a second power source, and the driving module is used to generate a driving current according to the potential of the control terminal of the driving module to drive the light-emitting module to emit light; The data writing module is connected to the first end of the coupling module, the second end of the coupling module is connected to the first end of the driving module, the data writing module is used to write the first voltage into the first end of the coupling module, and is also used to write the data voltage into the first end of the coupling module; The coupling module is used to couple the data voltage to the control terminal of the driving module; The first end of the compensation module is connected to the first end of the driving module, the second end of the compensation module is connected to the control end of the driving module, and the compensation module is used to write the threshold voltage of the driving module into the control end of the driving module.

2. The pixel circuit according to claim 1, characterized in that: It also includes a storage module, which is connected to the control end of the driving module and is used to store the threshold voltage of the driving module; Preferably, the control end of the compensation module is connected to the second scanning signal, and the control end of the data writing module is connected to the first scanning signal; The compensation module is used to respond to the second scanning signal and write the threshold voltage of the driving module into the control terminal of the driving module in the compensation stage; the data writing module is used to respond to the first scanning signal and write the first voltage into the first terminal of the coupling module in the compensation stage, and is also used to write the data voltage into the first terminal of the coupling module in the data writing stage; the driving module is used to generate a driving current according to the potential of the control terminal of the driving module in the light-emitting stage to drive the light-emitting module to emit light; Preferably, the driving module includes a first transistor, the compensation module includes a second transistor, the data writing module includes a third transistor, the coupling module includes a first capacitor, and the storage module includes a second capacitor; The first end of the light emitting module is connected to the first power source, and the second end of the light emitting module is connected to the first electrode of the first transistor; The second electrode of the first transistor is connected to the second power supply; A first electrode of the third transistor is connected to the data line, a second electrode of the third transistor is connected to the first end of the first capacitor, and a gate of the third transistor is connected to the first scanning signal; The second end of the first capacitor is connected to the first electrode of the first transistor; The first electrode of the second transistor is connected to the first electrode of the first transistor, the second electrode of the second transistor is connected to the gate of the first transistor, and the gate of the second transistor is connected to the second scanning signal; A first end of the second capacitor is connected to the gate of the first transistor, and a second end of the second capacitor is connected to the second electrode of the first transistor; Preferably, the first transistor is an N-type transistor; Preferably, the first transistor is an oxide transistor; Preferably, both the second transistor and the third transistor are N-type transistors; Preferably, the second transistor and the third transistor are both oxide transistors.

3. The pixel circuit according to claim 2, characterized in that: The data writing module is also used to write the second voltage into the first end of the coupling module in a first initialization phase; wherein the first initialization phase is before the compensation phase; The second voltage is less than the first voltage; Preferably, the second power supply is used to output a third voltage in the first initialization stage, so that the voltage difference across the light emitting module is smaller than a start-up voltage of the light emitting module.

4. The pixel circuit according to claim 2, characterized in that: Also included is a lighting control module; The light emitting module, the light emitting control module and the driving module are sequentially connected in series between the first power source and the second power source; The control end of the light emitting control module is connected to the first scanning signal; Preferably, the light emitting control module includes a fourth transistor, a first end of the light emitting module is connected to the first power supply, a first electrode of the fourth transistor is connected to the second end of the light emitting module, a second electrode of the fourth transistor is connected to the first electrode of the first transistor, and a gate of the fourth transistor is connected to the first scanning signal; Preferably, the fourth transistor is a P-type transistor; Preferably, the fourth transistor is a low temperature polysilicon transistor.

5. The pixel circuit according to claim 4, characterized in that: It also includes an initialization module, the initialization module is connected to a common node, the common node is a node where the light emitting module and the light emitting control module are connected, and the initialization module is used to transmit the voltage output by the first power supply to the common node in a second initialization phase; Preferably, the control end of the initialization module receives the second scanning signal, and the second initialization phase includes the compensation phase and the data writing phase; Preferably, the initialization module comprises a fifth transistor, a first electrode of the fifth transistor is connected to the first power supply, a second electrode of the fifth transistor is connected to the common node, and a gate of the fifth transistor is connected to the second scanning signal; Preferably, the fifth transistor is an N-type transistor; Preferably, the fifth transistor is an oxide transistor.

6. The pixel circuit according to any one of claims 2 to 5, characterized in that: The first power supply is a DC power supply, and the second power supply is an AC power supply; Preferably, the second power supply is used to output a third voltage in the compensation stage and the data writing stage so that the voltage difference across the light-emitting module is smaller than the start-up voltage of the light-emitting module, and is also used to output a fourth voltage in the light-emitting stage so that the voltage difference across the light-emitting module is larger than the start-up voltage of the light-emitting module, and the third voltage is larger than the fourth voltage.

7. The pixel circuit according to claim 6, characterized in that: The second power source is generated by a scan driver.

8. A method for driving a pixel circuit, characterized in that: The pixel circuit comprises a driving module, a light emitting module, a data writing module, a compensation module and a coupling module; the driving module and the light emitting module are connected in series between a first power source and a second power source, the data writing module is connected to a first end of the coupling module, the second end of the coupling module is connected to a first end of the driving module, the first end of the compensation module is connected to a first end of the driving module, and the second end of the compensation module is connected to a control end of the driving module; The driving method of the pixel circuit comprises: In the compensation stage, the data writing module is controlled to be turned on to write the first voltage into the first end of the coupling module, and the compensation module is controlled to be turned on to write the threshold voltage of the driving module into the control end of the driving module; In the data writing stage, the data writing module and the compensation module are controlled to be turned on to write the data voltage into the first end of the coupling module, and the data voltage is coupled to the control end of the driving module through the compensation module via the coupling module; In the light-emitting stage, the driving module generates a driving current according to the potential of the control terminal of the driving module to drive the light-emitting module to emit light.

9. The driving method of the pixel circuit according to claim 8, characterized in that: The pixel circuit further includes a storage module, and the storage module is connected to the control end of the driving module; The driving method of the pixel circuit further includes: In the first initialization phase: Control the data writing module to be turned on to write the second voltage into the first end of the coupling module; control the second power supply to output a third voltage, so that under the action of the storage module, the driving module is turned on and the voltage difference between the two ends of the light-emitting module is less than the start-up voltage of the light-emitting module; The first initialization phase is located before the compensation phase.

10. A display panel, characterized in that: The pixel circuit comprises the pixel circuit described in any one of claims 1 to 7.

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