Pixel driving circuit and display panel

Abstract

A pixel driving circuit and a display panel, the pixel driving circuit comprising an OLED, a data line, a driving module, a compensation module and a coupling module, the driving module comprising a first thin film transistor, the compensation module comprising a storage capacitor, and the coupling module comprising a coupling capacitor, the capacitance of the coupling capacitor being smaller than that of the storage capacitor, in a charging phase, the first thin film transistor being configured to output a first voltage to a second end of the storage capacitor and a second end of the coupling capacitor, in a light emitting phase, the storage capacitor and the coupling capacitor are charge coupled, and the voltage at the control end of the first thin film transistor is offset from the first voltage to a second voltage, the second voltage being smaller than the first voltage, the first thin film transistor being configured to output a first driving current to the OLED according to the second voltage and a first power voltage, so that the magnitude of the first driving current remains unchanged after the voltage variation range of the first data voltage is reduced, thereby reducing the power consumption of the data line without affecting the luminance of the OLED.

Description

Technical Field

[0001] This invention relates to the field of OLED display technology, and more specifically to a pixel driving circuit and a display panel. Background Technology

[0002] Organic light-emitting diode (OLED) display panels have become the core of modern display technology due to their superior characteristics such as self-illumination, high contrast, wide viewing angle, and flexibility. In active-matrix OLED displays, each pixel typically contains a driving thin-film transistor (TFT). This TFT generates a driving current based on the data voltage, causing the OLED to emit light according to a preset brightness. However, due to parasitic capacitance between the data lines and other conductors, and the large voltage fluctuation of the data lines, there is a problem of high power consumption. Summary of the Invention

[0003] The purpose of this invention is to provide a pixel driving circuit and a display panel to solve the problem of high power consumption caused by data lines.

[0004] To achieve the objectives of this invention, the following technical solution is provided: In a first aspect, the present invention provides a pixel driving circuit, comprising: an OLED; a data line; a driving module including a first thin-film transistor, a first terminal of the first thin-film transistor being electrically connected to the data line, and a second terminal of the first thin-film transistor being electrically connected to the anode of the OLED; a compensation module including a storage capacitor, the second terminal of the storage capacitor being electrically connected to both the second terminal of the first thin-film transistor and a control terminal, the first terminal of the storage capacitor being used to input a first power supply voltage; and a coupling module including a coupling capacitor, the first terminal of the coupling capacitor being electrically connected to both the data line and the first terminal of the first thin-film transistor, the second terminal of the coupling capacitor being electrically connected to both the second terminal of the first thin-film transistor and a control terminal, the capacitance value of the coupling capacitor being smaller than the capacitance value of the storage capacitor; wherein, the pixel driving circuit is in a... The driving cycle sequentially passes through a charging phase and a light-emitting phase. During the charging phase, the data line is used to output a first data voltage to the first terminal of the first thin-film transistor and the first terminal of the coupling capacitor. The first thin-film transistor is used to output a first voltage to the second terminal of the storage capacitor and the second terminal of the coupling capacitor according to the first data voltage and the threshold voltage of the first thin-film transistor. During the light-emitting phase, the first terminal of the coupling capacitor is used to input the first power supply voltage to cause charge coupling between the storage capacitor and the coupling capacitor, and to cause the voltage at the control terminal of the first thin-film transistor to shift from the first voltage to a second voltage, where the second voltage is less than the first voltage. The first thin-film transistor is used to output a first driving current to the OLED according to the second voltage and the first power supply voltage.

[0005] In one embodiment, the first thin-film transistor is a P-type thin-film transistor, and the first voltage is the difference between the first data voltage and the threshold voltage of the first thin-film transistor.

[0006] In one embodiment, during the charging phase, the data line is used to output a second data voltage to a first terminal of the first thin-film transistor and a first terminal of the coupling capacitor. The first thin-film transistor is used to output a third voltage to a second terminal of the storage capacitor and a second terminal of the coupling capacitor based on the second data voltage and a threshold voltage of the first thin-film transistor. During the light-emitting phase, the first terminal of the coupling capacitor is used to input the first power supply voltage to cause charge coupling between the storage capacitor and the coupling capacitor, and to shift the voltage at the control terminal of the first thin-film transistor from the third voltage to a fourth voltage, wherein the third voltage is less than the fourth voltage. The first thin-film transistor is used to output a second driving current to the OLED based on the fourth voltage and the first power supply voltage, wherein the second driving current is less than the first driving current. The second data voltage, the first power supply voltage, and the first data voltage are all positive values ​​and increase sequentially.

[0007] In one embodiment, the driving module further includes a second thin-film transistor and a third thin-film transistor. The first terminal of the second thin-film transistor is used to input the first power supply voltage. The second terminal of the second thin-film transistor is electrically connected to the first terminal of the first thin-film transistor. The second terminal of the first thin-film transistor is electrically connected to the first terminal of the third thin-film transistor. The second terminal of the third thin-film transistor is electrically connected to the anode of the OLED. During the charging phase, both the second and third thin-film transistors are turned off, and during the light-emitting phase, both the second and third thin-film transistors are turned on.

[0008] In one embodiment, the compensation module further includes a fourth thin-film transistor and a fifth thin-film transistor. The first terminal of the fourth thin-film transistor is electrically connected to the data line, the second terminal of the fourth thin-film transistor is electrically connected to the first terminal of the first thin-film transistor, the first terminal of the fifth thin-film transistor is electrically connected to the control terminal of the first thin-film transistor, and the second terminal of the fifth thin-film transistor is electrically connected to the second terminal of the first thin-film transistor. During the charging phase, both the fourth and fifth thin-film transistors are turned on, and during the light-emitting phase, both the fourth and fifth thin-film transistors are turned off.

[0009] In one embodiment, the coupling module further includes a sixth thin-film transistor, a first terminal of which is electrically connected to the data line, and a second terminal of which is electrically connected to the first terminal of the coupling capacitor; wherein, during the charging phase, the sixth thin-film transistor is turned on, and during the light-emitting phase, the sixth thin-film transistor is turned off.

[0010] In one embodiment, the pixel driving circuit further includes a reset module, which is electrically connected to the anode of the OLED, the second terminal of the storage capacitor, the second terminal of the coupling capacitor, and the control terminal of the first thin-film transistor.

[0011] In one embodiment, the reset module includes a seventh thin-film transistor and an eighth thin-film transistor. The first terminal of the seventh thin-film transistor and the first terminal of the eighth thin-film transistor are both used to input a reset voltage. The second terminal of the seventh thin-film transistor is electrically connected to the second terminal of the storage capacitor, the second terminal of the coupling capacitor, and the control terminal of the first thin-film transistor. The second terminal of the eighth thin-film transistor is electrically connected to the anode of the OLED.

[0012] In a second aspect, the present invention also provides a display panel, including a driver chip and a pixel driving circuit as described in any one of the embodiments of the first aspect, wherein the driver chip is electrically connected to the data line and is used to output the first data voltage.

[0013] In one embodiment, there are multiple pixel driving circuits arranged in an array of N rows and M columns, where N and M are both positive integers ≥ 2; there are M data lines, and multiple pixel driving circuits located in the same column are electrically connected to the same data line.

[0014] The pixel driving circuit provided by this invention sets the capacitance of the coupling capacitor to be less than that of the storage capacitor. The first end of the coupling capacitor is electrically connected to both the data line and the first end of the first thin-film transistor, and the second end of the coupling capacitor is electrically connected to both the second end of the first thin-film transistor and the control terminal. During the light-emitting phase, the voltage of the first end of the coupling capacitor is controlled to switch from the first data voltage to the first power supply voltage, causing charge coupling between the coupling capacitor and the storage capacitor. This also causes the voltage of the control terminal of the first thin-film transistor to decrease from the first voltage to the second voltage, so that the first thin-film transistor outputs a first driving current to the OLED according to the second voltage and the first power supply voltage. This reduces the magnitude of the first driving current while decreasing the voltage change amplitude of the first data voltage, thereby reducing the power consumption of the data line without affecting the OLED's brightness. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a structural diagram of a display panel according to one embodiment; Figure 2 This is a circuit diagram of a pixel driving circuit according to one embodiment; Figure 3 This is a circuit diagram of a proportional 7T1C pixel driving circuit.

[0017] Explanation of reference numerals in the attached figures: 1000 - Display panel, 100 - Pixel driving circuit, T1 - First thin-film transistor, T2 - Second thin-film transistor, T3 - Third thin-film transistor, T4 - Fourth thin-film transistor, T5 - Fifth thin-film transistor, T6 - Sixth thin-film transistor, T7 - ​​Seventh thin-film transistor, T8 - Eighth thin-film transistor, C1 - Storage capacitor, C2 - Coupling capacitor, EM - Enable signal line, G1 - First signal line, G2 - Second signal line, SOC - Driver chip, S - Data line, VINT - Reset voltage, ELVDD - First power supply voltage, ELVSS - Second power supply voltage. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that when a component is said to be "fixed" to another component, it can be directly on the other component or it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0020] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0021] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] Please refer to Figure 1 This invention provides a display panel 1000, including a driver chip SOC and a pixel driving circuit 100 according to an embodiment of the invention. The driver chip SOC is electrically connected to a data line S, and the driver chip SOC is used to output a first data voltage or a second data voltage to the data line S, so that the pixel driving circuit 100 is in a black state display or a white state display. The second data voltage is less than the first data voltage.

[0023] In a specific implementation, there are multiple pixel driving circuits 100, arranged in an array of N rows and M columns. There are M data lines S, and the multiple pixel driving circuits 100 located in the same column are all electrically connected to the same data line S. Here, N and M are both positive integers ≥ 2.

[0024] Please refer to Figure 2 The pixel driving circuit 100 in this embodiment of the invention includes an OLED, a data line S, a driving module, a compensation module, a coupling module, and a reset module.

[0025] The driving module includes a first thin-film transistor T1, a second thin-film transistor T2, and a third thin-film transistor T3. The first terminal of the second thin-film transistor T2 is used to input a first power supply voltage ELVDD. The second terminal of the second thin-film transistor T2 is electrically connected to the first terminal of the first thin-film transistor T1. The second terminal of the first thin-film transistor T1 is electrically connected to the first terminal of the third thin-film transistor T3. The second terminal of the third thin-film transistor T3 is electrically connected to the anode of the OLED, so that the second terminal of the first thin-film transistor T1 is electrically connected to the anode of the OLED. The cathode of the OLED is used to input a second power supply voltage ELVSS.

[0026] The compensation module includes a storage capacitor C1, a fourth thin-film transistor T4, and a fifth thin-film transistor T5. The first terminal of the storage capacitor C1 is connected to the first terminal of the second thin-film transistor T2 for inputting the first power supply voltage ELVDD. The second terminal of the storage capacitor C1 is electrically connected to the control terminal of the first thin-film transistor T1. The first terminal of the fourth thin-film transistor T4 is electrically connected to the data line S. The second terminal of the fourth thin-film transistor T4 is electrically connected to the first terminal of the first thin-film transistor T1, so that the first terminal of the first thin-film transistor T1 is electrically connected to the data line S. The first terminal of the fifth thin-film transistor T5 is electrically connected to the control terminal of the first thin-film transistor T1. The second terminal of the fifth thin-film transistor T5 is electrically connected to the second terminal of the first thin-film transistor T1, so that the second terminal of the storage capacitor C1 is electrically connected to the second terminal of the first thin-film transistor T1.

[0027] The coupling module includes a coupling capacitor C2 and a sixth thin-film transistor T6. The first terminal of the sixth thin-film transistor T6 is electrically connected to the data line S, and the second terminal of the sixth thin-film transistor T6 is electrically connected to the first terminal of the coupling capacitor C2, so that the first terminal of the coupling capacitor C2 is electrically connected to the data line S. The first terminal of the coupling capacitor C2 is also electrically connected to the first terminal of the first thin-film transistor T1, and the second terminal of the coupling capacitor C2 is electrically connected to the control terminal of the first thin-film transistor T1. The second terminal of the coupling capacitor C2 is also electrically connected to the first terminal of the fifth thin-film transistor T5, so that the second terminal of the coupling capacitor C2 is electrically connected to the second terminal of the first thin-film transistor T1.

[0028] The reset module is electrically connected to the anode of the OLED, the second terminal of the storage capacitor C1, the second terminal of the coupling capacitor C2, and the control terminal of the first thin-film transistor T1. The reset module is used to input a reset voltage VINT to the anode of the OLED, the second terminal of the storage capacitor C1, the second terminal of the coupling capacitor C2, and the control terminal of the first thin-film transistor T1 to eliminate the residual charge in the anode of the OLED, the second terminal of the storage capacitor C1, the second terminal of the coupling capacitor C2, and the control terminal of the first thin-film transistor T1 during the last display.

[0029] Specifically, the reset module includes a seventh thin-film transistor T7 and an eighth thin-film transistor T8. The first terminal of the seventh thin-film transistor T7 and the first terminal of the eighth thin-film transistor T8 are both used to input the reset voltage VINT. The second terminal of the seventh thin-film transistor T7 is electrically connected to the second terminal of the storage capacitor C1, the second terminal of the coupling capacitor C2, and the control terminal of the first thin-film transistor T1. The second terminal of the eighth thin-film transistor T8 is electrically connected to the anode of the OLED.

[0030] In a specific implementation, the control terminals of the second thin-film transistor T2 and the third thin-film transistor T3 are both electrically connected to the enable signal line EM. The enable signal line EM is used to receive an enable signal to enable the second thin-film transistor T2 and the third thin-film transistor T3 to turn on or off synchronously.

[0031] In a specific implementation, the control terminals of the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 are all electrically connected to the first signal line G1. The first signal line G1 is used to receive a first control signal to make the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 turn on or off synchronously.

[0032] In a specific implementation, the control terminal of the seventh thin-film transistor T7 is electrically connected to the second signal line G2, which is used to receive a second control signal to turn the seventh thin-film transistor T7 on or off.

[0033] In one driving cycle, the pixel driving circuit 100 sequentially passes through a reset phase, a charging phase, and a light-emitting phase. During the reset phase, the charging phase, and the light-emitting phase, the first terminal of the storage capacitor C1 is always input with the first power supply voltage ELVDD, that is, the voltage at the first terminal of the storage capacitor C1 is always equal to the first power supply voltage ELVDD.

[0034] During the reset phase, the enable signal controls the second thin-film transistor T2 and the third thin-film transistor T3 to turn off, the first control signal controls the seventh thin-film transistor T7 to turn on, and the second control signal controls the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 to turn off. The reset voltage VINT is input through the third thin-film transistor T3 to the second terminal of the storage capacitor C1, the second terminal of the coupling capacitor C2, and the control terminal of the first thin-film transistor T1 to clear the charge on the storage capacitor C1, the coupling capacitor C2, and the first thin-film transistor T1.

[0035] In one embodiment, during the charging phase, the aforementioned driver chip SOC outputs a first data voltage via data line S to cause the pixel driving circuit 100 to be displayed in a black state. The specific details of this embodiment are as follows: During the charging phase, the data line S is used to output a first data voltage to the first terminal of the first thin film transistor T1 and the first terminal of the coupling capacitor C2. The first thin film transistor T1 is used to output a first voltage to the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 according to the first data voltage and the threshold voltage of the first thin film transistor T1.

[0036] Specifically, the enable signal controls the second thin-film transistor T2 and the third thin-film transistor T3 to turn off, the first control signal controls the seventh thin-film transistor T7 to turn off, and the second control signal controls the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 to turn on. At this time, the fifth thin-film transistor T5 is connected to the control terminal and the second terminal of the first thin-film transistor T1, so that the first thin-film transistor T1 is in diode state.

[0037] The first data voltage output from the data line S is input to the first terminal of the coupling capacitor C2 through the sixth thin-film transistor T6, so that the first terminal of the coupling capacitor C2 has the first data voltage.

[0038] The first data voltage output from the data line S is also input to the first terminal of the first thin-film transistor T1 through the fourth capacitor. Under the action of the first data voltage, the voltage of the control terminal of the first thin-film transistor T1 decreases from the aforementioned reset voltage VINT until the gate-source voltage of the first thin-film transistor T1 is equal to the threshold voltage of the first thin-film transistor T1. At this point, the voltage of the control terminal of the first thin-film transistor T1 is the first voltage. Since the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 are both electrically connected to the control terminal of the first thin-film transistor T1, the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 both have the first voltage.

[0039] In this embodiment, the first thin-film transistor T1 is a P-type thin-film transistor, and the first voltage is the difference between the first data voltage and the threshold voltage of the first thin-film transistor T1, wherein the first data voltage is DATA1, and the threshold voltage of the first thin-film transistor T1 is Vth, that is, the first voltage is DATA1-Vth. Optionally, the first thin-film transistor T1 is an N-type thin-film transistor, and the first voltage can also be the sum of the first data voltage and the threshold voltage of the first thin-film transistor T1.

[0040] During the light-emitting stage, the first terminal of the coupling capacitor C2 is used to input the first power supply voltage ELVDD, so that the storage capacitor and the coupling capacitor are charged and the voltage of the control terminal of the first thin film transistor T1 is shifted from the first voltage to the second voltage, the second voltage being less than the first voltage. The first thin film transistor T1 is used to output the first driving current to the OLED according to the second voltage and the first power supply voltage ELVDD.

[0041] Specifically, the enable signal controls the second thin-film transistor T2 and the third thin-film transistor T3 to turn on, the first control signal controls the seventh thin-film transistor T7 to turn off, and the second control signal controls the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 to turn off.

[0042] During the light-emitting phase, the first power supply voltage ELVDD is input to the first terminal of the coupling capacitor C2 through the second thin-film transistor T2, causing the voltage at the first terminal of the coupling capacitor C2 to jump from the first data voltage to the first power supply voltage ELVDD. Therefore, the change in voltage at the first terminal of the coupling capacitor C2 is ELVDD - DATA1. Since the second terminals of the storage capacitor C1 and the coupling capacitor C2 are both connected to the control terminal of the first thin-film transistor T1, when the voltage at the second terminal of the coupling capacitor C2 changes, charge coupling occurs between the coupling capacitor C2 and the storage capacitor C1, thereby outputting a first offset voltage to the control terminal of the first thin-film transistor T1. The first offset voltage is: -(ELVDD - DATA1) × C2 / (C2 - C1). The control terminal of the first thin-film transistor T1 receives the first offset voltage and shifts from the first voltage to a second voltage. The second voltage is the sum of the first voltage and the first offset voltage, i.e., the second voltage is DATA1 - Vth - (ELVDD - DATA1) × C2 / (C2 - C1). The voltage value of the first data voltage is greater than the voltage value of the first power supply voltage, ELVDD, where DATA1 > ELVDD.

[0043] Furthermore, the first thin-film transistor T1 is turned on to a preset level under the control of the second voltage, and outputs a first drive current according to the first power supply voltage ELVDD input through the second thin-film transistor T2. The first drive current I1 = k × [ELVDD-DATA1-(ELVDD-DATA1) × C2 / (C2-C1)]^2.

[0044] Please refer to Figure 3 , Figure 3 As a comparative example of a 7T1C pixel driving circuit, when the 7T1C pixel driving circuit shown in the comparative example is in a black state display, it is used to drive the OLED to emit a driving current I0=k×(ELVDD-DATA0)^2 with a preset brightness, wherein ELVDD in the comparative example is equal to ELVDD in the present invention, and k in the comparative example is equal to k in the present invention.

[0045] In a specific implementation, the capacitance of coupling capacitor C2 is less than the capacitance of storage capacitor C1, so (ELVDD-DATA1)×C2 / (C2-C1)>0, that is, when DATA0 in the comparative example is equal to DATA1 in the present invention, I0<I1.

[0046] When DATA1 of the present invention is less than a certain value of DATA0, that is, when the maximum value of the first data voltage is reduced, the luminous brightness of the OLED of the present invention can be the same as that of the comparative OLED. After the voltage change amplitude of the first data voltage is reduced, the magnitude of the first driving current remains unchanged, thereby reducing the power consumption of the data line S without affecting the luminous brightness of the OLED.

[0047] The pixel driving circuit 100 provided by the present invention sets the capacitance of coupling capacitor C2 to be less than that of storage capacitor C1. The first end of coupling capacitor C2 is electrically connected to both the data line S and the first end of the first thin-film transistor T1, and the second end of coupling capacitor C2 is electrically connected to both the second end and the control end of the first thin-film transistor T1. During the light-emitting stage, the voltage of the first end of coupling capacitor C2 is controlled to switch from the first data voltage to the first power supply voltage ELVDD, so that coupling capacitor C2 and storage capacitor C1 are charge-coupled, and the voltage of the control end of the first thin-film transistor T1 is reduced from the first voltage to the second voltage, so that the first thin-film transistor T1 outputs a first driving current to the OLED according to the second voltage and the first power supply voltage ELVDD. After the voltage change amplitude of the first data voltage is reduced, the magnitude of the first driving current remains unchanged, thereby reducing the power consumption of the data line S without affecting the light-emitting brightness of the OLED.

[0048] Furthermore, since the first data voltage of multiple data lines S is output by the aforementioned driver chip SOC, the maximum value of the first data voltage required by the pixel driving circuit 100 in this embodiment of the invention is reduced, and the maximum voltage output by the driver chip SOC can also be reduced, thereby reducing the power consumption of the driver chip SOC and the power consumption of other components associated with the driver chip SOC.

[0049] In another embodiment, during the charging phase, the aforementioned driver chip SOC outputs a second data voltage via data line S to enable the pixel driving circuit 100 to display in a white state. The specific details of this embodiment are as follows: During the charging phase, the data line S is used to output a second data voltage to the first terminal of the first thin-film transistor T1 and the first terminal of the coupling capacitor C2. The first thin-film transistor T1 is used to output a third voltage to the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 according to the second data voltage and the threshold voltage of the first thin-film transistor T1.

[0050] Specifically, the enable signal controls the second thin-film transistor T2 and the third thin-film transistor T3 to turn off, the first control signal controls the seventh thin-film transistor T7 to turn off, and the second control signal controls the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 to turn on. At this time, the fifth thin-film transistor T5 is connected to the control terminal and the second terminal of the first thin-film transistor T1, so that the first thin-film transistor T1 is in diode state.

[0051] The second data voltage output from the data line S is input to the first terminal of the coupling capacitor C2 through the sixth thin-film transistor T6, so that the first terminal of the coupling capacitor C2 has the second data voltage.

[0052] The second data voltage output from data line S is also input to the first terminal of the first thin-film transistor T1 through the fourth capacitor. Under the action of the second data voltage, the voltage of the control terminal of the first thin-film transistor T1 decreases from the aforementioned reset voltage VINT until the gate-source voltage of the first thin-film transistor T1 is equal to the threshold voltage of the first thin-film transistor T1. At this point, the voltage of the control terminal of the first thin-film transistor T1 is the third voltage. Since the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 are both electrically connected to the control terminal of the first thin-film transistor T1, both the second terminal of the storage capacitor C1 and the second terminal of the coupling capacitor C2 have the third voltage.

[0053] In this embodiment, the first thin-film transistor T1 is a P-type thin-film transistor, and the third voltage is the difference between the second data voltage and the threshold voltage of the first thin-film transistor T1, i.e., the third voltage is DATA2-Vth. Optionally, the first thin-film transistor T1 is an N-type thin-film transistor, and the third voltage can also be the sum of the second data voltage and the threshold voltage of the first thin-film transistor T1.

[0054] During the light-emitting stage, the first terminal of the coupling capacitor C2 is used to input the first power supply voltage ELVDD, so that the storage capacitor and the coupling capacitor are charge-coupled, and the voltage at the control terminal of the first thin-film transistor T1 shifts from the third voltage to the fourth voltage, where the third voltage is less than the fourth voltage. The first thin-film transistor T1 is used to output a second driving current to the OLED according to the fourth voltage and the first power supply voltage ELVDD, where the second driving current is less than the first driving current. The second data voltage, the first power supply voltage ELVDD, and the first data voltage are all positive values ​​and increase sequentially.

[0055] Specifically, the enable signal controls the second thin-film transistor T2 and the third thin-film transistor T3 to turn on, the first control signal controls the seventh thin-film transistor T7 to turn off, and the second control signal controls the fourth thin-film transistor T4, the fifth thin-film transistor T5, the sixth thin-film transistor T6, and the eighth thin-film transistor T8 to turn off.

[0056] During the light-emitting phase, the first power supply voltage ELVDD is input to the first terminal of the coupling capacitor C2 through the second thin-film transistor T2, causing the voltage at the first terminal of the coupling capacitor C2 to jump from the second data voltage to the first power supply voltage ELVDD. The value of the second data voltage is DATA2, meaning the voltage change at the first terminal of the coupling capacitor C2 is ELVDD - DATA2. Since the second terminals of both the storage capacitor C1 and the coupling capacitor C2 are connected to the control terminal of the first thin-film transistor T1, when the voltage at the second terminal of the coupling capacitor C2 changes, charge coupling occurs between the coupling capacitor C2 and the storage capacitor C1, resulting in a second offset voltage output to the control terminal of the first thin-film transistor T1. The second offset voltage is -(ELVDD - DATA2) × C2 / (C2 - C1). The control terminal of the first thin-film transistor T1 receives the first offset voltage and shifts from the third voltage to the fourth voltage. The fourth voltage is the sum of the third voltage and the first offset voltage, i.e., DATA2 - Vth - (ELVDD - DATA2) × C2 / (C2 - C1). Among them, the voltage value of the second data voltage is less than the voltage value of the first power supply voltage ELVDD, that is, DATA2 < ELVDD.

[0057] Furthermore, the first thin-film transistor T1 is turned on to a preset level under the control of the fourth voltage, and outputs a second drive current according to the first power supply voltage ELVDD input through the second thin-film transistor T2. The second drive current I2=k×[ELVDD-DATA2-(ELVDD-DATA2)×C2 / (C2-C1)]^2.

[0058] When the 7T1C pixel driving circuit 100 shown in the comparative example is in white state, it drives the OLED to emit a driving current I0 = k × (ELVDD - DATA0`)^2 with a preset brightness, where ELVDD in the comparative example is equal to ELVDD in the present invention, and k in the comparative example is equal to k in the present invention.

[0059] In a specific implementation, the capacitance of coupling capacitor C2 is less than the capacitance of storage capacitor C1, so (ELVDD-DATA2)×C2 / (C2-C1)<0, that is, when DATA0` in the comparative example is equal to DATA2 in the present invention, I0>I2.

[0060] When DATA2 of the present invention is greater than a certain value of DATAO`, that is, when the maximum value of the second data voltage is increased, the luminous brightness of the OLED of the present invention can be the same as that of the OLED of the comparative example. After the voltage change amplitude of the second data voltage increases, the magnitude of the second driving current remains unchanged. This achieves the reduction of the difference between the first data voltage and the second data voltage on the data line S without affecting the luminous brightness of the OLED, thereby further reducing the power consumption on the data line S.

[0061] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and other indicators are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0062] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A pixel driving circuit, characterized in that, include: OLED; Data cable; The driving module includes a first thin-film transistor, a first terminal of which is electrically connected to the data line, and a second terminal of which is electrically connected to the anode of the OLED. The compensation module includes a storage capacitor, the second end of which is electrically connected to both the second end and the control end of the first thin-film transistor, and the first end of which is used to input a first power supply voltage. The coupling module includes a coupling capacitor, wherein a first end of the coupling capacitor is electrically connected to both the data line and the first end of the first thin-film transistor, and a second end of the coupling capacitor is electrically connected to both the second end of the first thin-film transistor and the control terminal. The capacitance value of the coupling capacitor is smaller than the capacitance value of the storage capacitor. In one driving cycle, the pixel driving circuit sequentially passes through a charging stage and a light-emitting stage. During the charging stage, the data line is used to output a first data voltage to the first terminal of the first thin-film transistor and the first terminal of the coupling capacitor. The first thin-film transistor is used to output a first voltage to the second terminal of the storage capacitor and the second terminal of the coupling capacitor according to the first data voltage and the threshold voltage of the first thin-film transistor. During the light-emitting stage, the first terminal of the coupling capacitor is used to input the first power supply voltage, so that the storage capacitor and the coupling capacitor are charged and the voltage of the control terminal of the first thin film transistor is shifted from the first voltage to a second voltage, the second voltage being less than the first voltage. The first thin film transistor is used to output a first driving current to the OLED according to the second voltage and the first power supply voltage.

2. The pixel driving circuit according to claim 1, characterized in that, The first thin-film transistor is a P-type thin-film transistor, and the first voltage is the difference between the first data voltage and the threshold voltage of the first thin-film transistor.

3. The pixel driving circuit according to claim 1, characterized in that, During the charging phase, the data line is used to output a second data voltage to the first terminal of the first thin-film transistor and the first terminal of the coupling capacitor, and the first thin-film transistor is used to output a third voltage to the second terminal of the storage capacitor and the second terminal of the coupling capacitor according to the second data voltage and the threshold voltage of the first thin-film transistor. During the light-emitting stage, the first terminal of the coupling capacitor is used to input the first power supply voltage, so that the storage capacitor and the coupling capacitor are charged and the voltage of the control terminal of the first thin film transistor is shifted from the third voltage to the fourth voltage, where the third voltage is less than the fourth voltage. The first thin film transistor is used to output a second driving current to the OLED according to the fourth voltage and the first power supply voltage, where the second driving current is less than the first driving current. Among them, the second data voltage, the first power supply voltage, and the first data voltage are all positive values ​​and increase sequentially.

4. The pixel driving circuit according to claim 1, characterized in that, The driving module further includes a second thin-film transistor and a third thin-film transistor. The first terminal of the second thin-film transistor is used to input the first power supply voltage. The second terminal of the second thin-film transistor is electrically connected to the first terminal of the first thin-film transistor. The second terminal of the first thin-film transistor is electrically connected to the first terminal of the third thin-film transistor. The second terminal of the third thin-film transistor is electrically connected to the anode of the OLED. During the charging phase, both the second and third thin-film transistors are turned off, and during the light-emitting phase, both the second and third thin-film transistors are turned on.

5. The pixel driving circuit according to claim 4, characterized in that, The compensation module further includes a fourth thin-film transistor and a fifth thin-film transistor. The first terminal of the fourth thin-film transistor is electrically connected to the data line, the second terminal of the fourth thin-film transistor is electrically connected to the first terminal of the first thin-film transistor, the first terminal of the fifth thin-film transistor is electrically connected to the control terminal of the first thin-film transistor, and the second terminal of the fifth thin-film transistor is electrically connected to the second terminal of the first thin-film transistor. During the charging phase, both the fourth and fifth thin-film transistors are turned on, and during the light-emitting phase, both the fourth and fifth thin-film transistors are turned off.

6. The pixel driving circuit according to claim 5, characterized in that, The coupling module further includes a sixth thin-film transistor, the first end of which is electrically connected to the data line, and the second end of which is electrically connected to the first end of the coupling capacitor. During the charging phase, the sixth thin-film transistor is turned on, and during the light-emitting phase, the sixth thin-film transistor is turned off.

7. The pixel driving circuit according to claim 5, characterized in that, The pixel driving circuit also includes a reset module, which is electrically connected to the anode of the OLED, the second terminal of the storage capacitor, the second terminal of the coupling capacitor, and the control terminal of the first thin-film transistor.

8. The pixel driving circuit according to claim 7, characterized in that, The reset module includes a seventh thin-film transistor and an eighth thin-film transistor. The first terminal of the seventh thin-film transistor and the first terminal of the eighth thin-film transistor are both used to input a reset voltage. The second terminal of the seventh thin-film transistor is electrically connected to the second terminal of the storage capacitor, the second terminal of the coupling capacitor, and the control terminal of the first thin-film transistor. The second terminal of the eighth thin-film transistor is electrically connected to the anode of the OLED.

9. A display panel, characterized in that, It includes a driver chip and a pixel driving circuit as described in any one of claims 1-8, wherein the driver chip is electrically connected to the data line and is used to output the first data voltage.

10. The display panel according to claim 9, characterized in that, The pixel driving circuit is multiple, and the multiple pixel driving circuits are arranged in an array of N rows and M columns, where N and M are both positive integers ≥ 2; There are M data lines, and multiple pixel driving circuits located in the same column are electrically connected to the same data line.

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