CN114120874B - Light emitting device driving circuit, backlight module and display panel - Google Patents

Light emitting device driving circuit, backlight module and display panel Download PDF

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Publication number
CN114120874B
CN114120874B CN202111404950.7A CN202111404950A CN114120874B CN 114120874 B CN114120874 B CN 114120874B CN 202111404950 A CN202111404950 A CN 202111404950A CN 114120874 B CN114120874 B CN 114120874B
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light
transistor
signal
light emitting
emitting device
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CN114120874A (en
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刘斌
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TCL Huaxing Photoelectric Technology Co Ltd
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TCL Huaxing Photoelectric Technology Co Ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The embodiment of the application provides a light emitting device driving circuit, a backlight module and a display panel, which comprise a light emitting device, a first light emitting control module, a second light emitting control module, a driving transistor, a data signal writing module, a first compensation module and a second compensation module. The first compensation module can compensate the threshold voltage of the driving transistor, and the second compensation module can compensate the threshold voltage of the light emitting device and the voltage drop of the driving circuit of the light emitting device, so that the problem of brightness attenuation of the light emitting device in the driving circuit of the light emitting device can be solved, and the display stability of the display panel is improved.

Description

Light emitting device driving circuit, backlight module and display panel
Technical Field
The application relates to the technical field of display, in particular to a light emitting device driving circuit, a backlight module and a display panel.
Background
Currently, display devices are mainly divided into two modes, passive driving and active driving. The passive driving mode has the advantages of low cost, but high resolution is difficult to realize due to the existence of cross talk, and the service lives of a power supply and a display device are short due to excessive transient current of a corresponding light emitting diode. The active driving mode is adopted for the existing display device, so that the service life of the display device is prolonged, and the power consumption of the display device is reduced.
When the display device is actively driven, the light emitting diode is in a long-time operating state, so that the threshold voltage of the driving transistor is shifted. To solve the threshold voltage shift problem, a compensation circuit design is introduced. For example, samsung and other companies typically employ 4T1C light emitting drive circuits to achieve internal compensation of threshold voltages. However, these light-emitting driving circuits have more scan signals and complex timing, and cannot compensate for variations in threshold voltage of the light-emitting device and voltage drop of the power supply signal.
Therefore, how to propose a light-emitting driving circuit, which not only can realize the internal compensation of the threshold voltage of the driving transistor, but also can compensate the variation of the threshold voltage of the light-emitting device and the voltage drop of the power supply signal is a difficulty that the existing panel manufacturers need to struggle.
Disclosure of Invention
The embodiment of the application aims to provide a light-emitting device driving circuit, a backlight module and a display panel, which can solve the technical problem that the existing light-emitting driving circuit cannot compensate the variation of the threshold voltage of a light-emitting device and the voltage drop of a power supply signal.
An embodiment of the present application provides a light emitting device driving circuit including:
The light-emitting device is connected in series with a light-emitting loop formed by the first power supply signal and the second power supply signal;
the first light-emitting control module is connected with a first light-emitting control signal and is connected in series with the light-emitting loop, and the first light-emitting control module is used for controlling the light-emitting loop to be turned on or off based on the first light-emitting control signal;
The second light-emitting control module is connected with a second light-emitting control signal and is connected in series with the light-emitting loop, and the second light-emitting control module is used for controlling the light-emitting loop to be turned on or turned off based on the second light-emitting control signal;
The source electrode of the driving transistor and the drain electrode of the driving transistor are connected in series to the light-emitting loop, the grid electrode of the driving transistor is electrically connected to a first node, the drain electrode of the driving transistor is electrically connected to a second node, and the source electrode of the driving transistor is electrically connected to the first light-emitting control module;
the data signal writing module is connected with a data signal and a first scanning signal, and is electrically connected to the second node, and the data signal writing module is used for conveying the data signal to the second node under the control of the first scanning signal;
The first compensation module is connected to a second scanning signal, is electrically connected to the source electrode of the driving transistor and the first node, and is used for compensating the threshold voltage of the driving transistor under the control of the second scanning signal;
the second compensation module is connected to a third scanning signal and the second power supply signal, and is electrically connected to the first node, and the second compensation module is used for compensating the threshold voltage of the light emitting device and the voltage drop of the light emitting device driving circuit under the control of the third scanning signal.
In the light emitting device driving circuit of the present application, the light emitting device driving circuit further includes an initialization module, the initialization module is connected to the first scan signal and the first power signal, and is electrically connected to the first node, and the initialization module is configured to initialize a potential of the first node under control of the first scan signal.
In the light emitting device driving circuit of the present application, the initialization module includes an initialization transistor and a first storage capacitor, a gate of the initialization transistor is connected to the first scan signal, a source of the initialization transistor is connected to the first power signal, a drain of the initialization transistor is electrically connected to one end of the first storage capacitor, and the other end of the first storage capacitor is electrically connected to the first node.
In the light emitting device driving circuit of the present application, the first light emitting control module includes a first light emitting control transistor, a gate of the first light emitting control transistor is connected to the first light emitting control signal, a source of the first light emitting control transistor is connected to the first power signal, and a drain of the first light emitting control transistor is electrically connected to the source of the driving transistor.
In the light emitting device driving circuit of the present application, the second light emitting control module includes a second light emitting control transistor, a gate of the second light emitting control transistor is connected to the second light emitting control signal, a source of the second light emitting control transistor is electrically connected to the second node, and a drain of the second light emitting control transistor is electrically connected to an input end of the light emitting device.
In the light emitting device driving circuit of the present application, the data signal writing module includes a data signal writing transistor, a gate of the data signal writing transistor is connected to the first scanning signal, a source of the data signal writing transistor is connected to the data signal, and a drain of the data signal writing transistor is electrically connected to the second node.
In the light emitting device driving circuit of the present application, the first compensation module includes a first compensation transistor, the first compensation transistor is connected to the second scanning signal, a source electrode of the first compensation transistor is electrically connected to the first node, and a drain electrode of the first compensation transistor is electrically connected to a source electrode of the driving transistor.
In the light emitting device driving circuit of the present application, the second compensation module includes a second compensation transistor and a second storage capacitor, wherein a gate of the second compensation transistor is connected to the third scan signal, a source of the second compensation transistor is connected to the second power signal, a drain of the second compensation transistor is electrically connected to one end of the second storage capacitor, and the other end of the second storage capacitor is electrically connected to the first node.
The embodiment of the application also provides a backlight module, which comprises:
A data line for providing a data signal;
A first light emission control signal line for providing a first light emission control signal;
A second light emission control signal line for providing a second light emission control signal;
a first scan line for providing a first scan signal;
a second scan line for providing a second scan signal;
A third scan line for providing a third scan signal; and
The light emitting device driving circuit as described above is connected to the data line, the first light emitting control signal line, the second light emitting control signal line, the first scan line, the second scan line, and the third scan line.
The embodiment of the application also provides a display panel which comprises a plurality of pixel units which are arranged in an array, wherein each pixel unit is provided with the light-emitting device driving circuit.
The light emitting device driving circuit, the backlight module and the display panel provided by the embodiment of the application comprise a light emitting device, a first light emitting control module, a second light emitting control module, a driving transistor, a data signal writing module, a first compensation module and a second compensation module. The first compensation module can compensate the threshold voltage of the driving transistor, and the second compensation module can compensate the threshold voltage of the light emitting device and the voltage drop of the driving circuit of the light emitting device, so that the problem of brightness attenuation of the light emitting device in the driving circuit of the light emitting device can be solved, and the display stability of the display panel is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a first implementation of a light emitting device driving circuit according to an embodiment of the present application.
Fig. 2 is a schematic structural diagram of a second implementation of a light emitting device driving circuit according to an embodiment of the present application.
Fig. 3 is a circuit schematic diagram of a second implementation of a light emitting device driving circuit according to an embodiment of the present application.
Fig. 4 is a timing chart of a driving circuit of a light emitting device according to an embodiment of the present application.
Fig. 5 is a schematic circuit diagram of an initialization stage of the light emitting device driving circuit according to the embodiment of the present application under the driving timing shown in fig. 4.
Fig. 6 is a schematic diagram of a circuit path of a light emitting device driving circuit according to an embodiment of the present application in a threshold voltage detection and data writing stage at the driving timing shown in fig. 4.
Fig. 7 is a schematic circuit diagram of a light emitting device driving circuit according to an embodiment of the present application in a transition stage of the driving timing shown in fig. 4.
Fig. 8 is a schematic diagram of a power supply voltage coupling stage of the light emitting device driving circuit according to the embodiment of the present application in the driving timing shown in fig. 4.
FIG. 9 is a schematic diagram illustrating a light emitting stage of the light emitting device driving circuit according to the embodiment of the present application under the driving timing shown in FIG. 4
Fig. 10 is a schematic structural diagram of a backlight module according to an embodiment of the application.
Fig. 11 is a schematic structural diagram of a display panel according to an embodiment of the application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
The transistors used in all embodiments of the present application may be thin film transistors or field effect transistors or other devices of the same characteristics, and the source and drain of the transistors used herein may be interchangeable because they are symmetrical. In the embodiment of the present application, in order to distinguish the two poles of the transistor except the gate, one pole is called a source and the other pole is called a drain. The middle terminal of the switching transistor is defined as a gate, the signal input terminal is defined as a source, and the output terminal is defined as a drain according to the form in the figure. In addition, the transistor adopted in the embodiment of the application is an N-type transistor, wherein the N-type transistor is turned on when the grid electrode is at a high level, and turned off when the grid electrode is at a low level.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a first implementation of a driving circuit of a light emitting device according to an embodiment of the present application. As shown in fig. 1, the light emitting device driving circuit 10 provided in the embodiment of the present application includes a light emitting device D, a first light emitting control module 101, a second light emitting control module 102, a driving transistor T1, a data signal writing module 103, a first compensation module 104, and a second compensation module 105. It should be noted that the light emitting device D may be a mini light emitting diode, a micro light emitting diode, or an organic light emitting diode.
The light emitting device D is connected in series to a light emitting circuit formed by the first power signal VLED and the second power signal VSS. The first light emitting control module 101 accesses the first light emitting control signal EM1. The first light emitting control module 101 is connected in series to the light emitting circuit. The second light emission control module 102 is connected to the second light emission control signal EM2. The second light-emitting control module 102 is connected in series to the light-emitting circuit. The source of the driving transistor T1 and the drain of the driving transistor T1 are connected in series to the light emitting circuit. The gate of the driving transistor T1 is electrically connected to the first node G. The drain of the driving transistor T1 is electrically connected to the second node S. The source of the driving transistor T1 is electrically connected to the first light emitting control module 101. The DATA signal writing module 103 accesses the DATA signal DATA and the first SCAN signal SCAN1. The data signal writing module 103 is electrically connected to the second node S. The first compensation module 104 accesses the second SCAN signal SCAN2. The first compensation module 104 is electrically connected to the source of the driving transistor T1 and the first node G. The second compensation module 105 is connected to the third SCAN signal SCAN3 and the second power signal VSS. The second compensation module 105 is electrically connected to the first node G.
It should be noted that, in the embodiment of the present application, the light emitting device D is only required to be connected in series to the light emitting circuit, and the light emitting device driving circuit 10 shown in fig. 1 only illustrates a specific position of the light emitting device D. That is, the light emitting device D may be connected in series at any position on the light emitting circuit.
Specifically, the driving transistor T1 is used to control the current flowing through the light emitting circuit. The first light emitting control module 101 is configured to control the light emitting circuit to be turned on or off based on the first light emitting control signal EM 1. The second light-emitting control module 102 is configured to control the light-emitting circuit to be turned on or off based on the second light-emitting control signal EM 2. The DATA signal writing module 103 is configured to transmit the DATA signal DATA to the second node S under the control of the first SCAN signal SCAN 1. The first compensation module 104 is configured to compensate the threshold voltage vth_t1 of the driving transistor T1 under the control of the second SCAN signal SCAN 2. The second compensation module 105 is used for compensating the voltage drop of the threshold voltage vth_led of the light emitting device D and the light emitting device driving circuit 10 under the control of the third SCAN signal SCAN 3.
According to the light emitting device driving circuit 10 provided by the embodiment of the application, the first compensation module 104 can be used for carrying out internal compensation on the threshold voltage Vth_T1 of the driving transistor T1, and the second compensation module 105 can be used for carrying out internal compensation on the threshold voltage Vth_LED of the light emitting device D and the voltage drop of the light emitting device driving circuit 10, so that the influence of the threshold voltage Vth_T1 of the driving transistor T1, the threshold voltage Vth_LED of the light emitting device D and the voltage drop of the light emitting device driving circuit 10 on the brightness of the light emitting device D is avoided, and the accuracy and the uniformity of the display of a display panel picture are further improved.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a second implementation of a driving circuit for a light emitting device according to an embodiment of the present application. As shown in fig. 2, the light emitting device driving circuit 10 provided in the embodiment of the present application further includes an initialization module 106. The initialization module 106 accesses the first SCAN signal SCAN1 and the first power signal VDD. The initialization module 106 is electrically connected to the first node G.
Specifically, the initialization module 106 is configured to initialize the potential of the first node G under the control of the first SCAN signal SCAN 1.
Referring to fig. 3, fig. 3 is a schematic circuit diagram of a second implementation of a driving circuit of a light emitting device according to an embodiment of the present application. As shown in fig. 2 and 3, the first light emitting control module 101 includes a first light emitting control transistor T2. The gate of the first light emitting control transistor T2 is connected to the first light emitting control signal EM1, the source of the first light emitting control transistor T2 is connected to the first power signal VDD, and the drain of the first light emitting control transistor T2 is electrically connected to the source of the driving transistor T1. The second light emission control module 102 includes a second light emission control transistor T3. The gate of the second light-emitting control transistor T3 is connected to the second light-emitting control signal EM2, the source of the second light-emitting control transistor T3 is electrically connected to the second node S, and the drain of the second light-emitting control transistor T3 is electrically connected to the input terminal of the light-emitting device D. The data signal writing module 103 includes a data signal writing transistor T4. The gate of the DATA signal writing transistor T4 is connected to the first SCAN signal SCAN1, the source of the DATA signal writing transistor T4 is connected to the DATA signal DATA, and the drain of the DATA signal writing transistor T4 is electrically connected to the first node S. The first compensation module 104 includes a first compensation transistor T5. The first compensation transistor T5 is connected to the second SCAN signal SCAN2, the source of the first compensation transistor T5 is electrically connected to the first node G, and the drain of the first compensation transistor T5 is electrically connected to the source of the driving transistor T1. The second compensation module 105 includes a second compensation transistor T6 and a second storage capacitor C2. The gate of the second compensation transistor T6 is connected to the third SCAN signal SCAN3, the source of the second compensation transistor T6 is connected to the second power signal VSS, the drain of the second compensation transistor T6 is electrically connected to one end of the second storage capacitor C2, and the other end of the second storage capacitor C2 is electrically connected to the first node G. The initialization module 106 includes an initialization transistor T7 and a first storage capacitor C1. The gate of the initializing transistor T7 is connected to the first SCAN signal SCAN1, the source of the initializing transistor T7 is connected to the first power signal VDD, the drain of the initializing transistor VDD is electrically connected to one end of the first storage capacitor C1, and the other end of the first storage capacitor C1 is electrically connected to the first node G.
It should be noted that, the first power signal VDD and the second power signal VSS are both used for outputting a predetermined voltage value. In addition, in the embodiment of the present application, the potential of the first power supply signal VDD is greater than the potential of the second power supply signal VSS. Specifically, the potential of the second power signal VSS may be the potential of the ground terminal. Of course, it is understood that the potential of the second power supply signal VSS may be other.
The driving transistor T1, the first light emitting control transistor T2, the second light emitting control transistor T3, the data signal writing transistor T4, the first compensation transistor T5, the second compensation transistor T6, and the initialization transistor T7 may be one or more of a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, and an amorphous silicon thin film transistor. Further, the transistors in the light emitting device driving circuit 10 provided in the embodiment of the present application may be set to be the same type of transistors, so as to avoid the influence of the differences between the different types of transistors on the light emitting device driving circuit 10.
Referring to fig. 4, fig. 4 is a timing chart of a driving circuit of a light emitting device according to an embodiment of the application. The combination of the first light emitting control signal EM1, the second light emitting control signal EM2, the DATA signal DATA, the first SCAN signal SCAN1, the second SCAN signal SCAN2 and the third SCAN signal SCAN sequentially corresponds to an initialization phase t1, a threshold voltage detection phase and a DATA writing phase t2, a transition phase t3, a power supply voltage coupling phase t4 and a light emitting phase t5; in other words, in a frame time, the driving control timing of the light emitting device driving circuit 10 provided by the embodiment of the application includes an initialization phase t1, a threshold voltage detection and data writing phase t2, a transition phase t3, a power supply voltage coupling phase t4 and a light emitting phase t5.
The light-emitting device D emits light in the light-emitting period t 5.
Specifically, in the initialization stage t1, the first SCAN signal SCAN1 is at a high potential, the second SCAN signal SCAN2 is at a high potential, the third SCAN signal SCAN3 is at a low potential, the DATA signal DATA is at a low potential, the first light emission control signal EM1 is at a high potential, and the second light emission control signal EM2 is at a low potential.
Specifically, in the threshold voltage detection and DATA writing stage t2, the first SCAN signal SCAN1 is at a high potential, the second SCAN signal SCAN2 is at a high potential, the third SCAN signal SCAN3 is at a low potential, the DATA signal DATA is at a high potential, the first light emission control signal EM1 is at a low potential, and the second light emission control signal EM2 is at a low potential.
Specifically, in the transition stage t3, the first SCAN signal SCAN1 is at a high potential, the second SCAN signal SCAN2 is at a low potential, the third SCAN signal SCAN3 is at a low potential, the DATA signal DATA is at a low potential, the first light emission control signal EM1 is at a low potential, and the second light emission control signal EM2 is at a low potential.
Specifically, in the power voltage coupling stage t4, the first SCAN signal SCAN1 is at a low potential, the second SCAN signal SCAN2 is at a low potential, the third SCAN signal SCAN3 is at a high potential, the DATA signal DATA is at a low potential, the first light emission control signal EM1 is at a low potential, and the second light emission control signal EM2 is at a low potential.
Specifically, in the light emitting stage t5, the first SCAN signal SCAN1 is at a low potential, the second SCAN signal SCAN2 is at a low potential, the third SCAN signal SCAN3 is at a low potential, the DATA signal DATA is at a low potential, the first light emitting control signal EM1 is at a high potential, and the second light emitting control signal EM2 is at a high potential.
Specifically, the first power signal VLED and the second power signal VSS are both dc voltage sources.
Specifically, referring to fig. 4 and 5, fig. 5 is a schematic circuit diagram of an initialization stage of the light emitting device driving circuit according to the embodiment of the present application under the driving timing shown in fig. 4.
In the initialization stage T1, the first SCAN signal SCAN1 is at a high potential, and the data signal write transistor T4 and the initialization transistor T7 are turned on under the control of the high potential of the first SCAN signal SCAN 1. The second SCAN signal SCAN2 is at a high potential, and the first compensation transistor T5 is turned on under the control of the high potential of the second SCAN signal SCAN 1. The first light emitting control signal EM1 is at a high potential, and the first light emitting control transistor T2 is turned on under the control of the high potential of the first light emitting control signal EM 1. Thereby, the initialization of the first node G is realized, and the voltage of the first node G is initialized to the voltage of the first power supply signal VDD.
In addition, when the voltage of the first node G becomes the voltage of the first power supply signal VDD, the driving transistor T1 is turned on under the high potential control of the first node G.
Meanwhile, in the initialization stage T1, the third SCAN signal SCAN3 is at a low level, so that the second compensation transistor T6 is turned off. The second emission control signal EM2 is low, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 6, fig. 6 is a schematic diagram illustrating a path of a light emitting device driving circuit according to an embodiment of the present application in a threshold voltage detection and data writing stage at the driving timing shown in fig. 4.
In the threshold voltage detection and DATA writing stage t2, the DATA signal DATA changes from low to high. The first SCAN signal SCAN1 is at a high potential, the initialization transistor T7 and the DATA signal writing transistor T4 are turned on under the control of the high potential of the first SCAN signal SCAN1, and the DATA signal DATA is sent to the second node S so that the potential of the second node S becomes data_h, wherein data_h is the voltage when the DATA signal DATA is at the high potential. The second SCAN signal SCAN2 is at a high potential, and the first compensation transistor T5 is turned on under the control of the high potential of the second SCAN signal SCAN2, so that the DATA signal writing transistor T4, the first compensation transistor T5 and the initialization transistor T7 form a diode structure, so that the potential of the first node G is reduced from the voltage of the first power signal VDD to data_h+vth_t1, where vth_t1 is the threshold voltage of the driving transistor T1.
Meanwhile, in the threshold voltage detection stage T2, the second compensation transistor T6 is turned off because the third SCAN signal SCAN3 is at a low potential. The first light emitting control signal EM1 is low, so that the first light emitting control transistor T2 is turned off. The second emission control signal EM2 is low, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and fig. 7, fig. 7 is a schematic circuit diagram of a light emitting device driving circuit in a transition stage of the driving timing shown in fig. 4 according to an embodiment of the present application.
In the transition period t3, the DATA signal DATA changes from high to low. The first SCAN signal SCAN1 is at a high potential, the DATA signal writing transistor T4 and the initializing transistor T7 are turned on under the control of the high potential of the first SCAN signal SCAN1, the DATA signal DATA is supplied to the second node S to change the potential of the second node S to data_l, wherein data_l is a voltage when the DATA signal DATA is at a low potential, and the potential of the first node is changed to data_h+vth_t1+v0, wherein v0= (data_h-data_l) [ c2/(c1+c2) ], C1 is the capacitance of the first storage capacitor C1, and C2 is the capacitance of the second storage capacitor C2.
Meanwhile, in the transition stage T3, since the second SCAN signal SCAN2 is at a low potential, the first compensation transistor T5 is turned off, and the third SCAN signal SCAN3 is at a low potential, the second compensation transistor T6 is turned off. The first light emitting control signal EM1 is low, so that the first light emitting control transistor T2 is turned off. The second emission control signal EM2 is low, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 8, fig. 8 is a schematic diagram illustrating a path of a power supply voltage coupling stage of the light emitting device driving circuit according to the embodiment of the present application in the driving timing shown in fig. 4.
In the power voltage coupling stage T4, the third SCAN signal SCAN3 is at a high level, the second compensation transistor T6 is turned on under the control of the high level of the third SCAN signal SCAN3, so that the potential of the second node S is changed from data_l to VSS, and the potential of the first node G is changed from data_h+vth_t1+v0 to data_h+vth_t1+v0+vss-data_l. Wherein, DATA_L is the voltage at which the DATA signal DATA is at a low potential.
Meanwhile, in the power supply voltage coupling stage T4, since the first SCAN signal SCAN1 is at a low potential, the data signal writing transistor T4 and the initializing transistor T7 are turned off. The second SCAN signal SCAN2 is low, so that the first compensation transistor T5 is turned off. The first light emitting control signal EM1 is low, so that the first light emitting control transistor T2 is turned off. The second emission control signal EM2 is low, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 9, fig. 9 is a schematic circuit diagram of a light emitting stage of the light emitting device driving circuit according to the embodiment of the present application under the driving timing shown in fig. 4.
In the light emitting period T5, the first light emitting control signal EM1 is at a high potential, and the first light emitting control transistor T2 is turned on under the control of the high potential of the first light emitting control signal EM 1. The second light emission control signal is at a high potential, and the second light emission control transistor T3 is turned on under the control of the high potential of the second light emission control signal EM 2. The third SCAN signal SCAN3 is at a high potential, and the second compensation transistor T6 is turned on under the control of the high potential of the third SCAN signal SCAN3, so that the potential of the second node S is changed from VSS to vss+vth_led, and the potential of the first node G is changed from data_h+vth_t1+v0+vss-data_l to data_h+vth_t1+v0+vss+vth_led-data_l. Wherein vth_led is the threshold voltage of the light emitting device D.
At this time, the calculation formula of the gate-drain voltage difference t1_vgs of the driving transistor T1 is as follows:
T1_Vgs＝(DATA_H+Vth_T1+V0+VSS+Vth_LED-DATA_L)-(VSS+Vth_LED)＝Vth_T1+V0+DATA_H-DATA_L
Wherein VSS is the voltage of the second power supply signal VSS, vth_t1 is the threshold voltage of the driving transistor T1, data_l is the voltage when the DATA signal DATA is at the low potential, data_h is the voltage when the DATA signal DATA is at the high potential, and vth_led is the threshold voltage of the light emitting device D.
As can be seen from the above, the calculation formula of I oled flowing through the light-emitting device D is as follows:
Ioled＝k*(Vth_T1+V0+DATA_H-DATA_L-Vth_T1)2＝k*(V0+DATA_H-DATA_L)2
Where k is the mobility of the light-emitting drive circuit. From the calculation formula of I oled flowing through the light emitting device D, I oled flowing through the light emitting device D is related to V0, data_h, and data_l only, and as can be seen from the above, V0 is related to the voltages of the first storage capacitor C1, the second storage capacitor C2, and the DATA signal DATA only. Therefore, the I oled flowing through the light emitting device D is independent of the threshold voltage vth_t1 of the driving transistor T1, the threshold voltage vth_led of the light emitting device D, and the voltage of the second power supply signal VSS, so as to avoid the voltage drops of the threshold voltage vth_t1 of the driving transistor T1, the threshold voltage vth_led of the light emitting device D, and the light emitting device driving circuit 10 from affecting the brightness of the light emitting device D, thereby improving the accuracy and uniformity of the display panel.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a backlight module according to an embodiment of the application. The embodiment of the application further provides a backlight module 100, which includes the data line 20, the first light emitting control signal line 30, the second light emitting control signal line 40, the first scan line 50, the second scan line 60, the third scan line 70, and the light emitting device driving circuit 10 described above. Wherein the data line 20 is used for providing a data signal. The first light emission control signal line 30 is for providing a first light emission control signal. The second light emission control signal line 40 is for supplying a second light emission control signal. The first scan line 50 is used for providing a first scan signal. The second scan line 60 is used for providing a second scan signal. The third scan line 70 is used to provide a third scan signal. The light emitting device driving circuit 10 is connected to the data line 20, the first light emission control signal line 30, the second light emission control signal line 40, the first scan line 50, the second scan line 60, and the third scan line 70. The light emitting device driving circuit 10 may be specifically referred to the above description of the light emitting device driving circuit, and will not be described herein.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a display panel according to an embodiment of the application. The embodiment of the present application further provides a display panel 200, which includes a plurality of pixel units 2000 arranged in an array, where each pixel unit 2000 includes the light emitting device driving circuit 10 described above, and the description of the light emitting device driving circuit 10 can be referred to above specifically, and will not be repeated here.
The above description is provided for the details of a light emitting device driving circuit, a backlight module and a display panel, and specific examples are applied to illustrate the principles and embodiments of the present application, and the above description of the embodiments is only for helping to understand the method and core ideas of the present application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, the present description should not be construed as limiting the present application.

Claims (8)

1. A light emitting device driving circuit, comprising:
The light-emitting device is connected in series with a light-emitting loop formed by the first power supply signal and the second power supply signal;
the first light-emitting control module is connected with a first light-emitting control signal and is connected in series with the light-emitting loop, and the first light-emitting control module is used for controlling the light-emitting loop to be turned on or off based on the first light-emitting control signal;
The second light-emitting control module is connected with a second light-emitting control signal and is connected in series with the light-emitting loop, and the second light-emitting control module is used for controlling the light-emitting loop to be turned on or turned off based on the second light-emitting control signal;
The source electrode of the driving transistor and the drain electrode of the driving transistor are connected in series to the light-emitting loop, the grid electrode of the driving transistor is electrically connected to a first node, the drain electrode of the driving transistor is electrically connected to a second node, and the source electrode of the driving transistor is electrically connected to the first light-emitting control module;
the data signal writing module is connected with a data signal and a first scanning signal, and is electrically connected to the second node, and the data signal writing module is used for conveying the data signal to the second node under the control of the first scanning signal;
The first compensation module is connected to a second scanning signal, is electrically connected to the source electrode of the driving transistor and the first node, and is used for compensating the threshold voltage of the driving transistor under the control of the second scanning signal;
The second compensation module is connected to a third scanning signal and the second power supply signal, is electrically connected to the first node, and is used for compensating the threshold voltage of the light emitting device and the voltage drop of the light emitting device driving circuit under the control of the third scanning signal;
The initialization module comprises an initialization transistor and a first storage capacitor, wherein the grid electrode of the initialization transistor is connected with the first scanning signal, the source electrode of the initialization transistor is connected with the first power supply signal, the drain electrode of the initialization transistor is electrically connected with one end of the first storage capacitor, and the other end of the first storage capacitor is electrically connected with the first node;
The second compensation module comprises a second compensation transistor and a second storage capacitor, wherein the grid electrode of the second compensation transistor is connected with the third scanning signal, the source electrode of the second compensation transistor is connected with the second power supply signal, the drain electrode of the second compensation transistor is electrically connected with one end of the second storage capacitor, and the other end of the second storage capacitor is electrically connected with the first node;
In the light emitting stage, a current flowing through the light emitting device is related to voltages of the first storage capacitor, the second storage capacitor, and the data signal, and is independent of a threshold voltage of the driving transistor, a threshold voltage of the light emitting device, and a voltage of the second power signal.
2. The light-emitting device driving circuit according to claim 1, wherein the initialization module is connected to the first scan signal and the first power signal, and is electrically connected to the first node, and the initialization module is configured to initialize a potential of the first node under control of the first scan signal.
3. The light emitting device driving circuit of claim 1, wherein the first light emitting control module comprises a first light emitting control transistor, a gate of the first light emitting control transistor is connected to the first light emitting control signal, a source of the first light emitting control transistor is connected to the first power signal, and a drain of the first light emitting control transistor is electrically connected to a source of the driving transistor.
4. The light-emitting device driving circuit according to claim 1, wherein the second light-emitting control module comprises a second light-emitting control transistor, a gate of the second light-emitting control transistor is connected to the second light-emitting control signal, a source of the second light-emitting control transistor is electrically connected to the second node, and a drain of the second light-emitting control transistor is electrically connected to an input terminal of the light-emitting device.
5. The light-emitting device driving circuit according to claim 1, wherein the data signal writing module comprises a data signal writing transistor, a gate of the data signal writing transistor is connected to the first scan signal, a source of the data signal writing transistor is connected to the data signal, and a drain of the data signal writing transistor is electrically connected to the second node.
6. The light-emitting device driving circuit according to claim 1, wherein the first compensation module comprises a first compensation transistor, the first compensation transistor is connected to the second scan signal, a source of the first compensation transistor is electrically connected to the first node, and a drain of the first compensation transistor is electrically connected to a source of the driving transistor.
7. A backlight module, comprising:
A data line for providing a data signal;
A first light emission control signal line for providing a first light emission control signal;
A second light emission control signal line for providing a second light emission control signal;
a first scan line for providing a first scan signal;
a second scan line for providing a second scan signal;
A third scan line for providing a third scan signal; and
The light emitting device driving circuit according to any one of claims 1 to 6, wherein the light emitting device driving circuit is connected to the data line, the first light emitting control signal line, the second light emitting control signal line, the first scan line, the second scan line, and the third scan line.
8. A display panel comprising a plurality of pixel cells arranged in an array, each of the pixel cells comprising the light emitting device driving circuit of any one of claims 1-6.
CN202111404950.7A 2021-11-24 2021-11-24 Light emitting device driving circuit, backlight module and display panel Active CN114120874B (en)

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