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 light emitting module, a driving module, a coupling module, a second voltage transmission unit and a voltage interval unit. The second voltage transmission unit is connected between the first power supply and the first end of the driving module, and the second voltage transmission unit is used for transmitting the voltage of the first power supply to the first end of the driving module in a compensation stage; the first end of the coupling module is connected with the control end of the driving module; the voltage interval unit is connected between the second end of the driving module and the second end of the coupling module, and the voltage interval unit is used for conducting in the compensation stage, so that the first power supply charges the coupling module, and the threshold voltage of the driving module is written into the second end of the coupling module. Through a charging type compensation mode, the discrete type of the threshold voltage of the driving module is compensated, the compensation of the positive bias or the negative bias of the threshold voltage is realized, the display uniformity is improved, and the display effect is 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] Organic light-emitting diode display panels emit light by being driven by electric current, so the characteristics of the driving device will affect the displayed grayscale brightness. When the characteristics of the driving devices corresponding to different pixels differ too much, uneven picture quality is likely to occur. Summary of the invention

[0003] The present invention provides a pixel circuit and a driving method thereof, and a display panel, so as to compensate for the threshold voltage of a driving module and improve display uniformity.

[0004] According to one aspect of the present invention, a pixel circuit is provided, including a light emitting module, a driving module, a coupling module, a second voltage transmission unit and a voltage interval unit;

[0005] The first end of the second voltage transmission unit is connected to the first power source, the second end of the second voltage transmission unit is connected to the first end of the driving module, and the second voltage transmission unit is used to transmit the voltage of the first power source to the first end of the driving module during the compensation stage;

[0006] The first end of the coupling module is connected to the control end of the driving module;

[0007] The first end of the voltage interval unit is connected to the second end of the driving module, and the second end of the voltage interval unit is connected to the second end of the coupling module. The voltage interval unit is used to be turned on in the compensation stage so that the first power supply charges the coupling module and writes the threshold voltage of the driving module into the second end of the coupling module.

[0008] Optionally, the pixel circuit further includes: a light emitting control module and a voltage writing module;

[0009] The light emitting module, the driving module and the light emitting control module are connected in series between a first power supply and a second power supply, and a voltage of the first power supply is greater than a voltage of the second power supply;

[0010] The voltage writing module is connected to the control terminal of the driving module, and is used to write the first voltage into the control terminal of the driving module in response to the first scanning signal during the compensation phase;

[0011] Optionally, the control end of the second voltage transmission unit and the control end of the voltage interval unit are both connected to the first scanning signal.

[0012] Optionally, the voltage writing module is further used to write the data voltage into the second end of the coupling module in response to the second scanning signal during the data writing phase;

[0013] The coupling module is used for coupling the data voltage to the control terminal of the driving module during the data writing phase;

[0014] Optionally, the voltage writing module is further used to write the second voltage into the control end of the driving module in response to the first scanning signal during the reset phase, and write the second voltage into the second end of the coupling module in response to the second scanning signal; wherein the reset phase is before the compensation phase;

[0015] The second voltage is lower than the first voltage.

[0016] Optionally, the voltage writing module includes a first voltage transmission unit and a data writing unit;

[0017] The first voltage transmission unit is connected to the control end of the driving module, and is used to write the first voltage into the control end of the driving module in response to the first scanning signal during the compensation phase, and is also used to write the second voltage into the control end of the driving module in response to the first scanning signal during the reset phase;

[0018] The data writing unit is connected to the second end of the coupling module, and is used to write the data voltage into the second end of the coupling module in response to the second scanning signal during the data writing phase, and is also used to write the second voltage into the second end of the coupling module in response to the second scanning signal during the reset phase.

[0019] Optionally, the first voltage transmission unit and the data writing unit are both connected to a data line;

[0020] The data line is used to transmit the second voltage in the reset phase, to transmit the first voltage in the compensation phase, and to transmit the data voltage in the data writing phase;

[0021] Optionally, the first voltage transmission unit includes a first transistor, and the data writing unit includes a second transistor;

[0022] A first electrode of the first transistor is connected to the data line, a second electrode of the first transistor is connected to the control end of the driving module, and a gate of the first transistor is connected to the first scanning signal;

[0023] A first electrode of the second transistor is connected to the data line, a second electrode of the second transistor is connected to the second end of the coupling module, and a gate of the second transistor is connected to the second scanning signal.

[0024] Optionally, both the first transistor and the second transistor are N-type transistors.

[0025] Optionally, the second voltage transmission unit includes a third transistor, and the voltage interval unit includes a fourth transistor;

[0026] A first electrode of the third transistor is connected to the first power supply, a second electrode of the third transistor is connected to the first end of the driving module, and a gate of the third transistor is connected to the first scanning signal;

[0027] A first electrode of the fourth transistor is connected to the second end of the driving module, a second electrode of the fourth transistor is connected to the second end of the coupling module, and a gate of the fourth transistor is connected to the first scanning signal.

[0028] Optionally, the third transistor and the fourth transistor are both N-type transistors.

[0029] Optionally, the light emitting module, the driving module and the light emitting control module are sequentially connected in series between the first power supply and the second power supply;

[0030] The light emitting control module is used to respond to the light emitting control signal and turn on during the light emitting stage, so that the driving current generated by the driving module according to the data voltage drives the light emitting module to emit light;

[0031] Optionally, the pixel circuit further includes a storage module, and the storage module is connected between the first power supply and the second end of the coupling module;

[0032] Optionally, the storage module includes a storage capacitor, a first end of the storage capacitor is connected to the first power supply, and a second end of the storage capacitor is connected to the second end of the coupling module;

[0033] Optionally, the driving module includes a fifth transistor, the light emitting control module includes a sixth transistor, and the coupling module includes a coupling capacitor;

[0034] The first end of the light emitting module is connected to the first power supply, the first electrode of the fifth transistor is connected to the second end of the light emitting module, the second electrode of the fifth transistor is connected to the first electrode of the sixth transistor, the second electrode of the sixth transistor is connected to the second power supply, and the gate of the sixth transistor is connected to the light emitting control signal;

[0035] A first end of the coupling capacitor is connected to the gate of the fifth transistor, and a second end of the coupling capacitor is connected to the second end of the voltage interval unit.

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

[0037] Optionally, the type of transistor included in the second voltage transmission unit is the same as the type of transistor included in the voltage spacing unit, and the type of the sixth transistor is the same as the type of transistor included in the second voltage transmission unit or the type of transistor included in the voltage spacing unit;

[0038] The valid pulse of the first scanning signal is located within the invalid pulse of the light emitting control signal; wherein the valid pulse of the first scanning signal is a pulse for controlling the second voltage transmission unit and the voltage interval unit to be turned on, and the invalid pulse of the light emitting control signal is a pulse for controlling the light emitting control module to be turned off;

[0039] Preferably, the sixth transistor, the transistor included in the second voltage transmission unit, and the transistor included in the voltage spacing unit are all N-type transistors.

[0040] Optionally, the type of transistor included in the second voltage transmission unit is the same as the type of transistor included in the voltage spacing unit, and the type of the sixth transistor is different from the type of transistor included in the second voltage transmission unit or the type of transistor included in the voltage spacing unit;

[0041] Optionally, the transistor included in the second voltage transmission unit and the transistor included in the voltage spacing unit are both N-type transistors, and the sixth transistor is a P-type transistor;

[0042] The first scanning signal is multiplexed into the light emitting control signal.

[0043] According to another aspect of the present invention, a method for driving a pixel circuit is provided, for driving the pixel circuit described in the above aspect, the method for driving the pixel circuit comprising:

[0044] During the compensation phase:

[0045] Controlling the second voltage transmission unit to be turned on to transmit the voltage of the first power supply to the first end of the driving module;

[0046] The voltage interval unit is controlled to be turned on, so that the first power source charges the coupling module, and the threshold voltage of the driving module is written into the second end of the coupling module.

[0047] According to another aspect of the present invention, a display panel is provided, comprising the pixel circuit described in the above aspect.

[0048] According to the technical solution of the embodiment of the present invention, in the compensation stage, after the second voltage transmission unit and the voltage interval unit are turned on, the voltage output by the first power supply is charged to the coupling module through the turned-on second voltage transmission unit, the driving module and the voltage interval unit, so as to write the threshold voltage of the driving module into the coupling module, and then couple the threshold voltage to the control end of the driving module through the coupling module. Through the charging compensation method, the discrete type of the threshold voltage of the driving module is compensated, and the compensation of the threshold voltage regardless of positive bias or negative bias is realized, thereby improving the display uniformity and the display effect.

[0049] 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

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0051] Figure 1 A schematic structural diagram of a pixel circuit provided by an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0053] Figure 3 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0054] Figure 4 A driving timing diagram of a pixel circuit provided by an embodiment of the present invention;

[0055] Figure 5 A schematic diagram of a specific structure of a pixel circuit provided by an embodiment of the present invention;

[0056] Figure 6 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention;

[0057] Figure 7 A driving timing diagram of another pixel circuit provided by an embodiment of the present invention;

[0058] Figure 8 A flowchart of a driving method of a pixel circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] 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.

[0060] 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.

[0061] As mentioned in the background technology, the display panel is prone to uneven image quality. The inventors have found that the reason is that as the display panel is used, the threshold voltage of the transistor included in the driving module in the pixel circuit is prone to shift. The brightness of the light-emitting module is related to the driving current generated by the driving module. The driving current I = k*(Vgs-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 value. Vs is the voltage difference between the control end and the second end of the driving module. Vth is the threshold voltage of the driving module. Therefore, when the threshold voltage of the driving module changes, even under the same data voltage, the generated driving current will not be the same, resulting in uneven display.

[0062] In view of the above technical problems, an embodiment of the present invention provides a novel pixel circuit, which realizes compensation of the threshold voltage regardless of positive bias or negative bias through a charging compensation method, thereby improving display uniformity.

[0063] 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 light emitting module 10, a driving module 11, a coupling module 15, a second voltage transmission unit 121 and a voltage interval unit 122;

[0064] A first end of the second voltage transmission unit 121 is connected to the first power source VDD, and a second end of the second voltage transmission unit 121 is connected to the first end d of the driving module 11. The second voltage transmission unit 121 is used to transmit the voltage of the first power source VDD to the first end d of the driving module 11 during the compensation phase;

[0065] A first end of the coupling module 15 is connected to a control end of the driving module 11;

[0066] The first end of the voltage interval unit 122 is connected to the second end s of the driving module 11, and the second end of the voltage interval unit 122 is connected to the second end n of the coupling module 15. The voltage interval unit 122 is used to be turned on in the compensation stage so that the first power supply VDD charges the coupling module 15 and writes the threshold voltage of the driving module 11 into the second end n of the coupling module 15.

[0067] In the embodiment of the present invention, the pixel circuit is exemplarily shown to further include a light-emitting control module 13. The light-emitting module 10, the driving module 11 and the light-emitting control module 13 are connected in series between a first power supply VDD and a second power supply VSS. The light-emitting control module 13 is used to shut down in response to a signal connected to the control terminal in any stage except the light-emitting stage, such as the compensation stage, to avoid the light-emitting module 10 from emitting light by mistake.

[0068] The light emitting module 10 includes a light emitting device, which may be an organic light emitting device or an inorganic light emitting device. In this embodiment, the light emitting device is OLED. The coupling module 15 may include a capacitor and have a coupling function. When the voltage at one end of the coupling module changes, the voltage at the other end changes by the same amount.

[0069] The second voltage transmission unit 121 is a switch unit, which connects the first power supply VDD with the first end d of the driving module 11 after being turned on. The voltage interval unit 122 is a switch unit, which connects the second end s of the driving module 11 with the second end n of the coupling module 15 after being turned on. Optionally, the second voltage transmission unit 121 is used to respond to the effective potential of the signal connected to its own control end during the compensation stage to conduct, so as to transmit the voltage of the first power supply VDD to the first end d of the driving module 11. The voltage interval unit 122 is used to respond to the effective potential of the signal intervened by its own control end during the compensation stage to conduct, so that the first end of the driving module 11 is charged to the second end n of the coupling module 15 through the driving module 11 and the voltage interval unit 122 until the voltage difference between the two ends of the coupling module 15 is the threshold voltage of the driving module 11, and the charging stops. The coupling module 15 is used to store the threshold voltage of the driving module 11.

[0070] According to the technical solution of the embodiment of the present invention, in the compensation stage, after the second voltage transmission unit and the voltage interval unit are turned on, the voltage output by the first power supply is charged to the coupling module through the turned-on second voltage transmission unit, the driving module and the voltage interval unit, so as to write the threshold voltage of the driving module into the coupling module, and then couple the threshold voltage to the control end of the driving module through the coupling module. Through the charging compensation method, the discrete type of the threshold voltage of the driving module is compensated, and the compensation of the threshold voltage regardless of positive bias or negative bias is realized, thereby improving the display uniformity and the display effect.

[0071] Figure 2 A schematic diagram of another pixel circuit provided by an embodiment of the present invention, referring to Figure 2 , based on the above embodiment, the pixel circuit further includes: a voltage writing module 14;

[0072] The light emitting module 10, the driving module 11 and the light emitting control module 13 are connected in series between a first power source VDD and a second power source VSS, and the voltage of the first power source VDD is greater than the voltage of the second power source VSS;

[0073] The voltage writing module 14 is connected to the control end of the driving module 11 and is used to write the first voltage into the control end of the driving module 11 in response to the first scanning signal S1 during the compensation phase.

[0074] In addition to the driving module 11, the light control module 13 and the voltage writing module 14 are switch modules, and each of the above modules may include at least one switch device. Optionally, the control end of the second voltage transmission unit 121 and the control end of the voltage interval unit 122 are both connected to the first scanning signal S1.

[0075] The working process of the pixel circuit includes a compensation stage. In the compensation stage, the voltage writing module 14 responds to the first scanning signal S1 and writes the first voltage into the control end of the driving module 11 to turn on the driving module 11. The second voltage transmission unit 121 and the voltage interval unit 122 are both turned on in response to the potential of the first scanning signal S1. After the second voltage transmission unit 121, the voltage interval unit 122 and the driving module 11 are turned on, the voltage output by the first power supply VDD is sequentially charged to the coupling module 15 through the second voltage transmission unit 121, the driving module 11 and the voltage interval unit 122, so as to write the voltage related to the threshold voltage of the driving module 11 into the second end n of the coupling module 15, and then the threshold voltage of the driving module 11 is coupled to the control end of the driving module 11 by the coupling effect of the coupling module 15. In the light-emitting stage, the light-emitting control module 13 is turned on in response to the signal connected to its own control end, and a path for driving current transmission is formed after turning on. Driving current I = k*(Vg-Vs-Vth) 2, Vs is the voltage of the second terminal s of the driving module 11. Since the voltage of the control terminal of the driving module 11 is a potential related to the threshold 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 11 and improves the uniformity of the screen display.

[0076] Continue to refer Figure 2 Optionally, the voltage writing module 14 is further used to write the data voltage into the second terminal n of the coupling module 15 in response to the second scanning signal S2 during the data writing phase;

[0077] The coupling module 15 is used to couple the data voltage to the control terminal of the driving module 11 during the data writing phase.

[0078] The voltage writing module 14 includes at least two switch modules, the control end of one switch module is connected to the first scanning signal S1, and the control end of the other switch module is connected to the second scanning signal S2, so as to transmit the first voltage and the data voltage respectively. The voltage writing module 14 includes a first output end and a second output end, the first output end is connected to the control end of the driving module 11, and the first output end is used to output the first voltage to the control end of the driving module 11 during the compensation stage. The second output end is connected to the second end n of the coupling module 15, and the second output end is used to output the data voltage to the second end n of the coupling module 15 during the data writing stage.

[0079] The working process of the pixel circuit includes a data writing stage. In the data writing stage, the voltage writing module 14 writes the data voltage into the second end n of the coupling module 15, and then utilizes the coupling effect of the coupling module 15 to couple the data voltage to the control end of the driving module 11. The driving module 11 generates a driving current according to the data voltage. In the light-emitting stage, the driving module 11 drives the light-emitting module 10 to emit light according to the driving current.

[0080] Continue to refer Figure 1 Optionally, the voltage writing module 14 is also used to write the second voltage into the control end of the driving module 11 in response to the first scanning signal S1 during the reset phase, and write the second voltage into the second end of the coupling module 15 in response to the second scanning signal S2; the second voltage is less than the first voltage. In a frame, the reset phase is before the compensation phase. That is, before the voltage writing module writes the first voltage in the compensation phase, the voltage writing module 14 is also used to write the second voltage into the control end of the driving module 11 in response to the first scanning signal S1 during the reset phase, and write the second voltage into the second end of the coupling module 15 in response to the second scanning signal S2; the second voltage is less than the first voltage.

[0081] The first output end of the voltage writing module 14 is used to output the second voltage and the first voltage to the control end of the driving module 11 in time-sharing mode. Specifically, the first output end is used to output the second voltage to the control end of the driving module 11 in the reset stage to reset the control end of the driving module 11 and the first end of the coupling module 15, and is also used to output the first voltage to the control end of the driving module 11 in the compensation stage to control the conduction of the driving module 11. The second output end of the voltage writing module 14 is used to output the second voltage and the data voltage to the second end n of the coupling module 15 in time-sharing mode. Specifically, the second output end is used to output the second voltage to the second end n of the coupling module 15 in the reset stage to reset the second end n of the coupling module 15, and is also used to output the data voltage to the second end of the coupling module 15 in the data writing stage, and couple the data voltage to the control end of the driving module 11 through the coupling module 15.

[0082] Figure 3 A schematic diagram of another pixel circuit provided by an embodiment of the present invention, referring to Figure 3 , Optionally, the voltage writing module 14 includes a first voltage transmission unit 141 and a data writing unit 142;

[0083] The first voltage transmission unit 141 is connected to the control end of the driving module 11, and is used to respond to the first scanning signal S1 in the compensation phase to write the first voltage into the control end of the driving module 11, and is also used to respond to the first scanning signal S1 in the reset phase to write the second voltage into the control end of the driving module 11;

[0084] The data writing unit 142 is connected to the second end n of the coupling module 15, and is used to respond to the second scanning signal S2 to write the data voltage into the second end n of the coupling module 15 during the data writing phase, and is also used to respond to the second scanning signal S2 to write the second voltage into the second end n of the coupling module 15 during the reset phase.

[0085] In an optional embodiment, the first end of the first voltage transmission unit 141 is connected to the first signal line, and the second end is connected to the control end of the driving module 11. The control end is connected to the first scan signal S1, and the first signal line outputs the second voltage in the reset stage and outputs the first voltage in the compensation stage. The first voltage transmission unit 141 is a switch unit, which connects the first end and the second end after being turned on. The first voltage transmission unit 141 is used to transmit the second voltage to the control end of the driving module 11 in response to the effective potential of the first scan signal S1 in the reset stage, and is also used to transmit the first voltage to the control end of the driving module 11 in response to the effective potential of the first scan signal S1 in the compensation stage. The effective potential of the first scan signal S1 here is the potential that controls the conduction of the first voltage transmission unit 141.

[0086] The first end of the data writing unit 142 is connected to the second signal line, the second end is connected to the second end n of the coupling module 15, the control end is connected to the second scanning signal S2, the second signal line outputs the second voltage in the reset phase, and outputs the data voltage in the data writing phase. The data writing unit 142 is a switch unit, which connects the first end and the second end after being turned on. The data writing unit 142 is used to respond to the effective potential of the second scanning signal S2 during the reset phase, and transmit the second voltage to the second end n of the coupling module 15. It is also used to respond to the effective potential of the second scanning signal S2 during the data writing phase, and transmit the data voltage to the second end n of the coupling module 15. Among them, the effective potential of the second scanning signal S2 here is the potential for controlling the data writing unit 142 to be turned on.

[0087] Continue to refer Figure 2 , Optionally, the first voltage transmission unit 141 and the data writing unit 142 are both connected to the data line Data;

[0088] The data line Data is used to transmit the second voltage in the reset phase, to transmit the first voltage in the compensation phase, and to transmit the data voltage in the data writing phase.

[0089] The first signal line and the second signal line are the same signal line, that is, both are data lines Data. The data line Data is used to transmit the second voltage in the reset phase, and transmit the second voltage to the control end of the driving module 11 and the first end of the coupling module 15 through the first voltage transmission unit 141, so as to reset the control end of the driving module 11 and the first end of the coupling module 15, and transmit the second voltage to the second end n of the coupling module 15 through the data writing unit 142, so as to reset the second end n of the coupling module 15. The data line Data is used to transmit the first voltage in the compensation phase, and transmit the first voltage to the control end of the driving module 11 through the first voltage transmission unit 141. In the compensation phase, the data writing unit 142 is turned off in response to the invalid potential of the second scanning signal S2. The data line Data is used to transmit the data voltage in the data writing phase, and transmit the data voltage to the second end n of the coupling module 15 through the data writing unit 142. In the data writing phase, the first voltage transmission unit 141 is turned off in response to the invalid potential of the first scanning signal S1. Here, the invalid potential of the first scan signal S1 is a potential for controlling the first voltage transmission unit 141 to be turned off, and the invalid potential of the second scan signal S2 is a potential for controlling the data writing unit 142 to be turned off.

[0090] The data line transmits the first voltage, the second voltage and the data voltage in a time-sharing manner, which can reduce the number of signal lines in the display area, is conducive to simplifying the layout, and improves the transmittance and resolution of the screen.

[0091] Continue to refer Figure 3Optionally, the pixel circuit further includes a storage module 16, and the storage module 16 is connected between the first power supply VDD and the second terminal n of the coupling module 15;

[0092] The light emitting module 10, the driving module 11 and the light emitting control module 13 are connected in series between the first power supply VDD and the second power supply VSS in sequence. Specifically, the first end of the light emitting module 11 is connected to the first power supply VDD, the second end of the light emitting module 11 is connected to the first end d of the driving module 11, the second end s of the driving module 11 is connected to the first end of the light emitting control module 13, the second end of the light emitting control module 13 is connected to the second power supply VSS, and the control end of the light emitting control module 13 is connected to the light emitting control signal EM.

[0093] The light emitting control module 13 is used to be turned on in response to the light emitting control signal EM during the light emitting stage, so that the driving module 11 generates a driving current according to the data voltage to drive the light emitting module 10 to emit light.

[0094] In this embodiment, it is exemplified that the second voltage transmission unit 121 , the voltage interval unit 122 , and the first voltage transmission unit 141 are all turned on in response to the same potential, and are turned off in response to the same potential.

[0095] Figure 4 A driving timing diagram of a pixel circuit provided by an embodiment of the present invention, Figure 4 Applies to Figure 3 The pixel circuit shown in Figure 2 is shown in Figure 2. Figure 3 and Figure 4 , the working process of the pixel circuit includes:

[0096] In the reset phase t1, the first voltage transmission unit 141 is turned on in response to the high level of the first scan signal S1, and the second voltage Vref_L transmitted by the data line Data is transmitted to the control end of the driving module 11 and the first end of the coupling module 15. The data writing unit 142 is turned on in response to the high level of the second scan signal S2, and the second voltage Vref_L is transmitted to the second end n of the coupling module 15. The second voltage transmission unit 121 is turned on in response to the high level of the first scan signal S1, and the voltage output by the first power supply VDD is transmitted to the first end d of the driving module 11. The voltage spacing unit 122 is turned on in response to the high level of the first scan signal S1, and the second voltage Vref_L transmitted by the data line Data is transmitted to the second end s of the driving module 11 via the voltage spacing unit 122. The light emitting control module 13 is turned off in response to the low level of the light emitting control signal EM. In the reset phase t1, the control end of the driving module 11, the first end of the coupling module 15, the second end n of the coupling module 15 and the second end s of the driving module 11 are all reset to the second voltage Vref_L, and the first end d of the driving module 11 is reset to the voltage output by the first power supply VDD.

[0097] In the compensation phase t2, the data writing unit 142 is turned off in response to the low level of the second scanning signal S2, the light-emitting control module 13 is turned off in response to the low level of the light-emitting control signal EM, and the first voltage transmission unit 141, the second voltage transmission unit 121 and the voltage interval unit 122 are all turned on in response to the high level of the first scanning signal S1. The turned-on first voltage transmission unit 141 transmits the first voltage Vref_H transmitted by the data line Data to the control end of the driving module 11. The voltage difference between the control end and the second end s of the driving module 11 is greater than the threshold voltage Vth of the driving module 11, and the driving module 11 is turned on. After the driving module 11 is turned on, the first power supply VDD charges the coupling module 15 and the storage module 16 until the voltage Vs of the second end s of the driving module 11 is Vref_H-Vth, and the driving module 11 is turned off.

[0098] In the data writing stage t3, the first voltage transmission unit 141, the second voltage transmission unit 121 and the voltage interval unit 122 are all turned off in response to the low level of the first scanning signal S1, the light-emitting control module 13 is turned off in response to the low level of the light-emitting control signal EM, and the data writing unit 142 is turned on in response to the high level of the second scanning signal S2 to transmit the data voltage Vdata transmitted by the data line Data to the second end n of the coupling module 15. Under the coupling action of the coupling module 15, the potential Vg of the control end of the driving module 11 is Vref_H+(Vdata-Vref_H+Vth)=Vdata+Vth.

[0099] In the light-emitting stage t4, the first voltage transmission unit 141, the second voltage transmission unit 121 and the voltage interval unit 122 are all turned off in response to the low level of the first scanning signal S1. The data writing unit 142 is turned off in response to the low level of the second scanning signal S2. The light-emitting control module 13 is turned on in response to the high level of the light-emitting control signal EM, and the driving module 11 generates a driving current according to the data voltage to drive the light-emitting module 10 to emit light. Among them, the driving current I=1 / 2*μ*Cox*W / L*(Vdata-V2) 2 ; μ is the electron mobility, Cox is the capacitance of the channel per unit area, W / L is the width-to-length ratio, V2 is the voltage output by the second power supply VSS, and in this embodiment, the first power supply VDD and the second power supply VSS are both DC power supplies.

[0100] It can be seen from the formula of the driving current I that the magnitude of the driving current I is independent of the threshold voltage Vth of the driving module 11, and the change of the threshold voltage Vth is compensated, so that the threshold voltage Vth can be compensated for positive and negative, and the display uniformity is improved. At the same time, the first power supply VDD is formed by whole-layer evaporation, and there is a whole layer of conductive layer in the display area. There is no need to set up additional signal wiring of the first power supply VDD. There are only data lines Data and signal wiring of the second power supply VSS in the pixel circuit. The fewer signal wiring is conducive to improving the transmittance of the screen, and is also conducive to high-resolution design.

[0101] Based on the above embodiments, an embodiment of the present invention further provides a specific structure of a pixel circuit. Figure 5 A specific structural diagram of a pixel circuit provided by an embodiment of the present invention, referring to Figure 3 and Figure 5 , Optionally, the first voltage transmission unit 141 includes a first transistor T1, and the data writing unit 142 includes a second transistor T2;

[0102] A first electrode of the first transistor T1 is connected to the data line Data, a second electrode of the first transistor T1 is connected to the control end of the driving module 11, and a gate of the first transistor T1 is connected to the first scanning signal S1;

[0103] A first electrode of the second transistor T2 is connected to the data line Data, a second electrode of the second transistor T2 is connected to the second end n of the coupling module 15, and a gate of the second transistor T2 is connected to the second scanning signal S2.

[0104] The first transistor T1 and the second transistor T2 may both be N-type transistors and further oxide transistors to reduce leakage current, or may both be P-type transistors and further low-temperature polysilicon transistors to reduce screen power consumption.

[0105] The second voltage transmission unit 121 includes a third transistor T3, and the voltage interval unit 122 includes a fourth transistor T4;

[0106] A first electrode of the third transistor T3 is connected to the first power supply VDD, a second electrode of the third transistor T3 is connected to the first end d of the driving module 11, and a gate of the third transistor T3 is connected to the first scanning signal S1;

[0107] A first electrode of the fourth transistor T4 is connected to the second end s of the driving module 11 , a second electrode of the fourth transistor T4 is connected to the second end n of the coupling module 15 , and a gate of the fourth transistor T4 is connected to the first scanning signal S1 .

[0108] The third transistor T3 and the fourth transistor T4 may both be N-type transistors, and further be oxide transistors to reduce leakage current, or may both be P-type transistors, and further be low-temperature polysilicon transistors to reduce screen power consumption.

[0109] The storage module 16 includes a storage capacitor C2, a first end of the storage capacitor C2 is connected to the first power supply VDD, and a second end of the storage capacitor C2 is connected to the second end n of the coupling module 15;

[0110] The driving module 11 includes a fifth transistor T5, the light emitting control module 13 includes a sixth transistor T6, and the coupling module 15 includes a coupling capacitor C1;

[0111] The first end of the light emitting module 10 is connected to the first power supply VDD, the first electrode of the fifth transistor T5 is connected to the second end of the light emitting module 10, the second electrode of the fifth transistor T5 is connected to the first electrode of the sixth transistor T6, the gate of the fifth transistor T5 is respectively connected to the first end of the coupling module 15 and the voltage writing module 14, specifically connected to the first end of the coupling capacitor C1 and the second electrode of the first transistor T1, the second electrode of the sixth transistor T6 is connected to the second power supply VSS, and the gate of the sixth transistor T6 is connected to the light emitting control signal EM;

[0112] A first end of the coupling capacitor C1 is connected to the gate of the fifth transistor T5 , and a second end of the coupling capacitor C1 is connected to a second end of the voltage interval unit 122 , specifically, to a second electrode of the fourth transistor T4 .

[0113] In this embodiment, the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 are all N-type transistors to reduce the leakage current. In other embodiments, in order to reduce the power consumption of the screen, the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4 and the sixth transistor T6 can all be PMOS transistors, which is not specifically limited. Figure 5 The driving timing of the pixel circuit shown can be referred to Figure 4 , and the working process is Figure 3 The pixel circuits shown are the same and will not be described again.

[0114] refer to Figure 3-Figure 5Optionally, the type of transistor included in the second voltage transmission unit 121 is the same as the type of transistor included in the voltage spacing unit 122, that is, the type of the third transistor T3 and the fourth transistor T4 is the same, and the type of the sixth transistor T6 is the same as the type of the transistor included in the second voltage transmission unit 121 or the type of the transistor included in the voltage spacing unit 122. In this embodiment, the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 are exemplarily shown to be N-type transistors.

[0115] The valid pulse of the first scanning signal S1 is located within the invalid pulse of the light emitting control signal EM, so that the light emitting control module 13 is turned off in the reset stage and the compensation stage to prevent the light emitting module 10 from erroneously emitting light. The valid pulse of the first scanning signal S1 is a pulse for controlling the conduction of the second voltage transmission unit 121 and the voltage interval unit 122, and the invalid pulse of the light emitting control signal EM is a pulse for controlling the turn-off of the light emitting control module 13.

[0116] In this embodiment, the first scanning signal S1 is generated by a group of gate driving circuits, the second scanning signal S2 is generated by a group of gate driving circuits, and the light-emitting control signal EM is generated by a group of gate driving circuits. In this embodiment, only three groups of gate driving circuits are required, and the structure is simple.

[0117] Figure 6 A schematic diagram of the structure of another pixel circuit provided by an embodiment of the present invention, Figure 7 A driving timing diagram of another pixel circuit provided by an embodiment of the present invention, Figure 7 The drive timing shown is applicable to Figure 6 The pixel circuit shown in Figure 2 is shown in Figure 2. Figure 6 and Figure 7 Optionally, the type of transistor included in the second voltage transmission unit 121 is the same as the type of transistor included in the voltage interval unit 122, and the type of the sixth transistor T6 is different from the type of transistor included in the second voltage transmission unit 121 or the type of transistor included in the voltage interval unit 122;

[0118] The first scan signal S1 is multiplexed into the light emitting control signal EM.

[0119] In this embodiment, the second voltage transmission unit 121 includes T6 as a P-type transistor, that is, the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4 and the fifth transistor T5 are all N-type transistors, and the sixth transistor T6 is a P-type transistor. Figure 6 The working process of the pixel circuit shown is similar to Figure 3The working process of the pixel circuit shown is similar and will not be described again. After the first scanning signal S1 is multiplexed into the light emitting control signal EM, the entire display panel only needs two sets of gate driving circuits, that is, the first scanning signal S1 is generated by one set of gate driving circuits, and the second scanning signal S2 is generated by one set of gate driving circuits, which is conducive to achieving a narrow frame.

[0120] The embodiment of the present invention further provides a driving method of a pixel circuit. Figure 8 A flowchart of a driving method of a pixel circuit provided by an embodiment of the present invention, referring to Figure 1 and Figure 8 , the method comprising:

[0121] S110: In the compensation stage, the second voltage transmission unit 121 is controlled to be turned on to transmit the voltage of the first power supply VDD to the first end d of the driving module 11; the voltage interval unit 122 is controlled to be turned on so that the first power supply VDD charges the coupling module 15 and writes the threshold voltage of the driving module 11 to the second end n of the coupling module 15.

[0122] After controlling the second voltage transmission unit 121 and the voltage spacing unit 122 to be turned on, the first power supply VDD is connected to the second terminal n of the coupling module 15, and the first power supply VDD sequentially charges the coupling module 15 through the first voltage transmission unit 121, the driving module 11 and the voltage spacing unit 122, so as to write the threshold voltage of the driving module 11 into the second terminal n of the coupling module 15 to achieve compensation for the threshold voltage of the driving module 11.

[0123] According to the technical solution of the embodiment of the present invention, in the compensation stage, the voltage output by the first power supply is charged to the coupling module through the turned-on second voltage transmission unit 121, the driving module and the voltage interval unit 122, so as to write the threshold voltage of the driving module into the second end of the coupling module. By means of a charging compensation method, the discrete type of the threshold voltage of the driving module is compensated, and compensation of the threshold voltage regardless of positive or negative bias is achieved, thereby improving display uniformity and enhancing display effect.

[0124] 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.

[0125] 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.

[0126] 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: A light emitting module, a driving module, a coupling module, a second voltage transmission unit and a voltage spacing unit; The first end of the second voltage transmission unit is connected to the first power source, the second end of the second voltage transmission unit is connected to the first end of the driving module, and the second voltage transmission unit is used to transmit the voltage of the first power source to the first end of the driving module during the compensation stage; The first end of the coupling module is connected to the control end of the driving module; The first end of the voltage interval unit is connected to the second end of the driving module, and the second end of the voltage interval unit is connected to the second end of the coupling module. The voltage interval unit is used to be turned on in the compensation stage so that the first power supply charges the coupling module and writes the threshold voltage of the driving module into the second end of the coupling module.

2. The pixel circuit according to claim 1, characterized in that: It also includes a light emitting control module and a voltage writing module; The light emitting module, the driving module and the light emitting control module are connected in series between a first power supply and a second power supply, and a voltage of the first power supply is greater than a voltage of the second power supply; The voltage writing module is connected to the control terminal of the driving module, and is used to write the first voltage into the control terminal of the driving module in response to the first scanning signal during the compensation phase; Preferably, the control end of the second voltage transmission unit and the control end of the voltage interval unit are both connected to the first scanning signal.

3. The pixel circuit according to claim 2, characterized in that: The voltage writing module is also used to write the data voltage into the second end of the coupling module in response to the second scanning signal during the data writing phase; The coupling module is used for coupling the data voltage to the control terminal of the driving module during the data writing phase; Preferably, the voltage writing module is further used to write the second voltage into the control end of the driving module in response to the first scanning signal during the reset phase, and write the second voltage into the second end of the coupling module in response to the second scanning signal; wherein the reset phase is before the compensation phase; The second voltage is lower than the first voltage.

4. The pixel circuit according to claim 3, characterized in that: The voltage writing module includes a first voltage transmission unit and a data writing unit; The first voltage transmission unit is connected to the control end of the driving module, and is used to write the first voltage into the control end of the driving module in response to the first scanning signal during the compensation phase, and is also used to write the second voltage into the control end of the driving module in response to the first scanning signal during the reset phase; The data writing unit is connected to the second end of the coupling module, and is used to write the data voltage into the second end of the coupling module in response to the second scanning signal during the data writing phase, and is also used to write the second voltage into the second end of the coupling module in response to the second scanning signal during the reset phase.

5. The pixel circuit according to claim 4, characterized in that: The first voltage transmission unit and the data writing unit are both connected to the data line; The data line is used to transmit the second voltage in the reset phase, to transmit the first voltage in the compensation phase, and to transmit the data voltage in the data writing phase; Preferably, the first voltage transmission unit includes a first transistor, and the data writing unit includes a second transistor; A first electrode of the first transistor is connected to the data line, a second electrode of the first transistor is connected to the control end of the driving module, and a gate of the first transistor is connected to the first scanning signal; A first electrode of the second transistor is connected to the data line, a second electrode of the second transistor is connected to the second end of the coupling module, and a gate of the second transistor is connected to the second scanning signal; Preferably, both the first transistor and the second transistor are N-type transistors; Preferably, the second voltage transmission unit includes a third transistor, and the voltage interval unit includes a fourth transistor; A first electrode of the third transistor is connected to the first power supply, a second electrode of the third transistor is connected to the first end of the driving module, and a gate of the third transistor is connected to the first scanning signal; A first electrode of the fourth transistor is connected to the second end of the driving module, a second electrode of the fourth transistor is connected to the second end of the coupling module, and a gate of the fourth transistor is connected to the first scanning signal; Preferably, the third transistor and the fourth transistor are both N-type transistors.

6. The pixel circuit according to any one of claims 2 to 5, characterized in that: The light emitting module, the driving module and the light emitting control module are sequentially connected in series between the first power source and the second power source; The light-emitting control module is used to respond to the light-emitting control signal and turn on during the light-emitting stage, so that the driving current generated by the driving module according to the data voltage drives the light-emitting module to emit light; Preferably, the pixel circuit further comprises a storage module, and the storage module is connected between the first power supply and the second end of the coupling module; Preferably, the storage module comprises a storage capacitor, a first end of the storage capacitor is connected to the first power supply, and a second end of the storage capacitor is connected to the second end of the coupling module; Preferably, the driving module includes a fifth transistor, the light emitting control module includes a sixth transistor, and the coupling module includes a coupling capacitor; The first end of the light emitting module is connected to the first power supply, the first electrode of the fifth transistor is connected to the second end of the light emitting module, the second electrode of the fifth transistor is connected to the first electrode of the sixth transistor, the second electrode of the sixth transistor is connected to the second power supply, and the gate of the sixth transistor is connected to the light emitting control signal; A first end of the coupling capacitor is connected to the gate of the fifth transistor, and a second end of the coupling capacitor is connected to the second end of the voltage interval unit; Preferably, the fifth transistor is an N-type transistor.

7. The pixel circuit according to claim 6, characterized in that: The type of transistor included in the second voltage transmission unit is the same as the type of transistor included in the voltage spacing unit, and the type of the sixth transistor is the same as the type of transistor included in the second voltage transmission unit or the type of transistor included in the voltage spacing unit; The valid pulse of the first scanning signal is located within the invalid pulse of the light emitting control signal; wherein the valid pulse of the first scanning signal is a pulse for controlling the second voltage transmission unit and the voltage interval unit to be turned on, and the invalid pulse of the light emitting control signal is a pulse for controlling the light emitting control module to be turned off; Preferably, the sixth transistor, the transistor included in the second voltage transmission unit, and the transistor included in the voltage spacing unit are all N-type transistors.

8. The pixel circuit according to claim 6, characterized in that: The type of transistor included in the second voltage transmission unit is the same as the type of transistor included in the voltage spacing unit, and the type of the sixth transistor is different from the type of transistor included in the second voltage transmission unit or the type of transistor included in the voltage spacing unit; Preferably, the transistor included in the second voltage transmission unit and the transistor included in the voltage interval unit are both N-type transistors, and the sixth transistor is a P-type transistor; Preferably, the first scanning signal is multiplexed into the light emitting control signal.

9. A method for driving a pixel circuit, characterized in that: Used to drive the pixel circuit according to any one of claims 1 to 8, the driving method of the pixel circuit comprising: During the compensation phase: Controlling the second voltage transmission unit to be turned on to transmit the voltage of the first power supply to the first end of the driving module; The voltage interval unit is controlled to be turned on, so that the first power source charges the coupling module, and the threshold voltage of the driving module is written into the second end of the coupling module.

10. A display panel, characterized in that: The pixel circuit comprises the pixel circuit described in any one of claims 1 to 8.

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