CN114120874A - Light emitting device driving circuit, backlight module and display panel - Google Patents
Light emitting device driving circuit, backlight module and display panel Download PDFInfo
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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
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
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Abstract
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 threshold voltage of the driving transistor can be compensated through the first compensation module, and the threshold voltage of the light-emitting device and the voltage drop of the light-emitting device driving circuit can be compensated through the second compensation module, so that the problem of brightness attenuation of the light-emitting device in the light-emitting device driving circuit can be solved, and the display stability of the display panel can be improved.
Description
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
At present, display devices are mainly classified into two modes, i.e., passive driving and active driving. The passive driving method has the advantages of low cost, but high resolution is difficult to realize due to the existence of cross talk, and the service life of the power supply and the display device is short due to the overlarge transient current of the corresponding light emitting diode. The active drive is provided with a thin film transistor corresponding to each pixel, and the existence of the capacitor enables the active drive to avoid the problems of cross crosstalk and overlarge transient current, so that the conventional display device generally adopts an active drive mode, thereby prolonging the service life of the display device and reducing the power consumption of the display device.
When the display device is driven actively, the threshold voltage of the driving transistor may shift because the light emitting diode may be operated for a long time. In order to solve the problem of threshold voltage offset, a compensation circuit design is introduced. For example, samsung et al generally use a 4T1C light emitting driving circuit to achieve internal compensation of threshold voltage. However, these light-emitting driving circuits have many scanning signals and complicated timing, and cannot compensate for variations in threshold voltage of the light-emitting device and voltage drop of the power signal.
Therefore, how to provide a light emitting driving circuit to compensate the threshold voltage of the driving transistor and the voltage drop variation of the light emitting device and the power signal is a difficult problem for the existing panel manufacturers.
Disclosure of Invention
An object of the embodiments of the present application is 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 threshold voltage of the light emitting device and the voltage drop variation of the power signal.
The 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 a first power signal and a second power 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 switched on or switched off based on the first light-emitting control signal;
the second light-emitting control module is connected to a second light-emitting control signal and is connected in series to the light-emitting loop, and the second light-emitting control module is used for controlling the light-emitting loop to be switched on or switched off based on the second light-emitting control signal;
a source of the driving transistor and a drain of the driving transistor are connected in series to the light emitting circuit, a gate of the driving transistor is electrically connected to a first node, a drain of the driving transistor is electrically connected to a second node, and a source of the driving transistor is electrically connected to the first light emitting control module;
the data signal writing module is accessed to 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 transmitting 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 and is electrically connected to the source electrode of the driving transistor and the first node, and the first compensation module 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 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 scanning 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 the control of the first scanning 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 another 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 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 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.
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 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 the source 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, 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 another end of the second storage capacitor is electrically connected to the first node.
The embodiment of the present application further provides a backlight module, including:
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;
the first scanning line is used for providing a first scanning 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, wherein the light emitting device driving circuit is connected to the data line, the first light emission control signal line, the second light emission control signal line, the first scan line, the second scan line, and the third scan line.
The embodiment of the application further provides a display panel, which comprises a plurality of pixel units 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 threshold voltage of the driving transistor can be compensated through the first compensation module, and the threshold voltage of the light-emitting device and the voltage drop of the light-emitting device driving circuit can be compensated through the second compensation module, so that the problem of brightness attenuation of the light-emitting device in the light-emitting device driving circuit can be solved, and the display stability of the display panel can be improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a first implementation manner of a light emitting device driving circuit provided in an embodiment of the present application.
Fig. 2 is a schematic structural diagram of a second implementation manner of a light emitting device driving circuit provided in an embodiment of the present application.
Fig. 3 is a circuit diagram of a second implementation manner of a light emitting device driving circuit provided in an embodiment of the present application.
Fig. 4 is a timing diagram of a light emitting device driving circuit according to an embodiment of the present application.
Fig. 5 is a schematic path diagram of an initialization stage of a light emitting device driving circuit according to an embodiment of the present application under the driving timing shown in fig. 4.
Fig. 6 is a schematic path diagram of a threshold voltage detection and data writing stage of the light emitting device driving circuit according to the embodiment of the present application at the driving timing shown in fig. 4.
Fig. 7 is a schematic path diagram of a transition stage of a light emitting device driving circuit according to an embodiment of the present application at the driving timing shown in fig. 4.
Fig. 8 is a schematic path diagram of a power supply voltage coupling stage of a light emitting device driving circuit according to an embodiment of the present application at the driving timing shown in fig. 4.
Fig. 9 is a schematic diagram of a path of a light emitting stage of a light emitting device driving circuit according to an 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 present application.
Fig. 11 is a schematic structural diagram of a display panel according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The transistors used in all embodiments of the present application may be thin film transistors or field effect transistors or other devices with the same characteristics, and since the source and drain of the transistors used herein are symmetrical, the source and drain may be interchanged. In the embodiment of the present application, to distinguish two poles of a transistor except for a gate, one of the two poles is referred to as a source, and the other pole is referred to as a drain. The form in the drawing provides that the middle end of the switching transistor is a grid, the signal input end is a source, and the output end is a drain. In addition, the transistors used in the embodiments of the present application are N-type transistors, wherein the N-type transistors are turned on when the gates are at a high level and turned off when the gates are at a low level.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a first implementation manner of a light emitting device driving circuit provided in 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 loop formed by the first power signal VLED and the second power signal VSS. The first lighting control module 101 receives a first lighting control signal EM 1. The first lighting control module 101 is connected in series to the lighting circuit. The second light emission control module 102 receives a second light emission control signal EM 2. The second light emitting control module 102 is connected in series to the light emitting loop. 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 lighting control module 101. The DATA signal writing module 103 receives the DATA signal DATA and the first SCAN signal SCAN 1. The data signal writing module 103 is electrically connected to the second node S. The first compensation module 104 accesses the second SCAN signal SCAN 2. 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 coupled 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, it is only necessary to ensure that the light emitting device D is connected in series to the light emitting loop, and the light emitting device driving circuit 10 shown in fig. 1 only illustrates one 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 loop.
Specifically, the driving transistor T1 is used to control the current flowing through the light emitting loop. The first lighting control module 101 is configured to control the lighting circuit to be turned on or off based on the first lighting control signal EM 1. The second light-emitting control module 102 is configured to control the light-emitting loop to be turned on or off based on the second light-emitting control signal EM 2. The DATA signal writing module 103 is used for transmitting 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 used for compensating 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 to compensate for the threshold voltage Vth _ LED of the light emitting device D and the voltage drop of the light emitting device driving circuit 10 under the control of the third SCAN signal SCAN 3.
The light emitting device driving circuit 10 provided in the embodiment of the application can perform internal compensation on the threshold voltage Vth _ T1 of the driving transistor T1 through the first compensation module 104, and can perform 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 through the second compensation module 105, so as to prevent 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 from affecting the brightness of the light emitting device D, and further improve the accuracy and uniformity of the display panel.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a light emitting device driving circuit according to a second embodiment of the present disclosure. 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 circuit diagram illustrating a light emitting device driving circuit according to a second embodiment of the present disclosure. As shown in fig. 2 and 3, the first light emission control module 101 includes a first light emission 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 write block 103 includes a data signal write 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, a source of the first compensation transistor T5 is electrically connected to the first node G, and a 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 initialization transistor T7 is connected to the first SCAN signal SCAN1, the source of the initialization transistor T7 is connected to the first power signal VDD, the drain of the initialization 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 signal VDD is greater than the potential of the second power 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 signal VSS may be other.
It should be noted that the driving transistor T1, the first light emission controlling transistor T2, the second light emission controlling transistor T3, the data signal writing transistor T4, the first compensating transistor T5, the second compensating transistor T6, and the initializing transistor T7 may be one or more of a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, or 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 on the light emitting device driving circuit 10 caused by the difference between different types of transistors.
Referring to fig. 4, fig. 4 is a timing diagram of a light emitting device driving circuit according to an embodiment of the present disclosure. The combination of the first emission control signal EM1, the second emission control signal EM2, the DATA signal DATA, the first SCAN signal SCAN1, the second SCAN signal SCAN2, and the third SCAN signal SCAN corresponds to an initialization phase t1, a threshold voltage detection phase and DATA write phase t2, a transition phase t3, a power voltage coupling phase t4, and an emission phase t 5; that is, in one frame time, the driving control timing of the light emitting device driving circuit 10 according to the embodiment of the present invention includes an initialization phase t1, a threshold voltage detection and data writing phase t2, a transition phase t3, a power voltage coupling phase t4, and a light emitting phase t 5.
Note that the light-emitting device D emits light at the light-emission period t 5.
Specifically, in the initialization stage t1, the first SCAN signal SCAN1 is at a high level, the second SCAN signal SCAN2 is at a high level, the third SCAN signal SCAN3 is at a low level, the DATA signal DATA is at a low level, the first emission control signal EM1 is at a high level, and the second emission control signal EM2 is at a low level.
Specifically, in the threshold voltage detecting and DATA writing stage t2, the first SCAN signal SCAN1 is at a high level, the second SCAN signal SCAN2 is at a high level, the third SCAN signal SCAN3 is at a low level, the DATA signal DATA is at a high level, the first emission control signal EM1 is at a low level, and the second emission control signal EM2 is at a low level.
Specifically, in the transition period t3, the first SCAN signal SCAN1 is at a high level, the second SCAN signal SCAN2 is at a low level, the third SCAN signal SCAN3 is at a low level, the DATA signal DATA is at a low level, the first emission control signal EM1 is at a low level, and the second emission control signal EM2 is at a low level.
Specifically, during the power voltage coupling stage t4, the first SCAN signal SCAN1 is at a low voltage level, the second SCAN signal SCAN2 is at a low voltage level, the third SCAN signal SCAN3 is at a high voltage level, the DATA signal DATA is at a low voltage level, the first emission control signal EM1 is at a low voltage level, and the second emission control signal EM2 is at a low voltage level.
Specifically, in the light emitting period t5, the first SCAN signal SCAN1 is at a low voltage level, the second SCAN signal SCAN2 is at a low voltage level, the third SCAN signal SCAN3 is at a low voltage level, the DATA signal DATA is at a low voltage level, the first light emission control signal EM1 is at a high voltage level, and the second light emission control signal EM2 is at a high voltage level.
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 path diagram of an initialization stage of a light emitting device driving circuit provided in 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 high, and the data signal writing transistor T4 and the initialization transistor T7 are turned on under the control of the high level of the first SCAN signal SCAN 1. The second SCAN signal SCAN2 is at a high level, and the first compensating transistor T5 is turned on under the control of the high level of the second SCAN signal SCAN 1. The first emission control signal EM1 is at a high potential, and the first emission control transistor T2 is turned on under the high potential control of the first emission control signal EM 1. Thereby, the initialization of the first node G is achieved, and the voltage of the first node G is initialized to the voltage of the first power 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 period T1, the third SCAN signal SCAN3 is low, such that the second compensation transistor T6 is turned off. The second emission control signal EM2 is at a low potential, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and fig. 6, fig. 6 is a schematic path diagram of a threshold voltage detection and data writing stage of the light emitting device driving circuit provided in the embodiment of the present application at the driving timing shown in fig. 4.
During the threshold voltage detection and DATA writing phase t2, the DATA signal DATA changes from low to high. The first SCAN signal SCAN1 is high, and the initialization transistor T7 and the DATA signal writing transistor T4 are turned on under the control of the high voltage of the first SCAN signal SCAN1 to supply the DATA signal DATA to the second node S, such that the potential of the second node S becomes DATA _ H, where DATA _ H is the voltage at which the DATA signal DATA is high. The second SCAN signal SCAN2 is at a high level, and the first compensation transistor T5 is turned on under the control of the high level 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, thereby making the voltage drop of the first node G from 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 detecting period T2, since the third SCAN signal SCAN3 is low, the second compensating transistor T6 is turned off. The first emission control signal EM1 is low, causing the first emission control transistor T2 to turn off. The second emission control signal EM2 is at a low potential, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 7, fig. 7 is a schematic path diagram of a transition stage of a light emitting device driving circuit provided in the embodiment of the present application at the driving timing shown in fig. 4.
In the transition period t3, the DATA signal DATA changes from high to low. The first SCAN signal SCAN1 is at a high level, and the DATA signal writing transistor T4 and the initializing transistor T7 are turned on under the control of the high level of the first SCAN signal SCAN1 to transmit the DATA signal DATA to the second node S, so that the potential of the second node S becomes DATA _ L, where DATA _ L is a voltage when the DATA signal DATA is at a low level, and the potential of the first node becomes DATA _ H + Vth _ T1+ V0, where V0 ═ DATA (H-DATA _ L) [ C2/(C1+ C2) ], C1 is a capacitance of the first storage capacitance C1, and C2 is a capacitance of the second storage capacitance C2.
Meanwhile, in the transition period T3, the first compensation transistor T5 is turned off due to the low level of the second SCAN signal SCAN2, and the second compensation transistor T6 is turned off due to the low level of the third SCAN signal SCAN 3. The first emission control signal EM1 is low, causing the first emission control transistor T2 to turn off. The second emission control signal EM2 is at a low potential, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 8, fig. 8 is a schematic path diagram of a power supply voltage coupling stage of a light emitting device driving circuit provided in the embodiment of the present application at the driving timing shown in fig. 4.
In the power voltage coupling period T4, the third SCAN signal SCAN3 is at a high level, the second compensating 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. DATA _ L is a voltage when the DATA signal DATA is at a low voltage level.
Meanwhile, during the power voltage coupling period T4, the data signal writing transistor T4 and the initialization transistor T7 are turned off due to the low level of the first SCAN signal SCAN 1. The second SCAN signal SCAN2 is low, so that the first compensation transistor T5 is turned off. The first emission control signal EM1 is low, causing the first emission control transistor T2 to turn off. The second emission control signal EM2 is at a low potential, so that the second emission control transistor T3 is turned off.
Specifically, referring to fig. 4 and 9, fig. 9 is a schematic path diagram of a light emitting stage of a light emitting device driving circuit provided in the embodiment of the present application at 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 high potential control of the first light emitting control signal EM 1. The second emission control signal is at a high potential, and the second emission control transistor T3 is turned on under the high potential control of the second emission control signal EM 2. 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, such 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. Where Vth _ LED is a threshold voltage of the light emitting device D.
At this time, the calculation formula of the gate-to-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
here, VSS is a voltage of the second power signal VSS, Vth _ T1 is a threshold voltage of the driving transistor T1, DATA _ L is a voltage when the DATA signal DATA is at a low potential, DATA _ H is a voltage when the DATA signal DATA is at a high potential, and Vth _ LED is a threshold voltage of the light emitting device D.
As can be seen from the above, I flows through the light emitting device DoledThe calculation formula of (a) 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 emission driving circuit. By flowing through I of the light-emitting device DoledOf the calculation formula, I flowing through the light emitting device DoledIt is only related to V0, DATA _ H, and DATA _ L, and it can be seen from the above that V0 is only related to the voltages of the first storage capacitor C1, the second storage capacitor C2, and the DATA signal DATA. Thus, I flows through the light emitting device DoledThe threshold voltage Vth _ T1 of the driving transistor T1 and the threshold voltage Vt of the light emitting device DThe h _ LED and the second power signal VSS are independent of each other, so that 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 are prevented from affecting the brightness of the light emitting device D, and the accuracy and uniformity of the display panel are improved.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a backlight module according to an embodiment of the present disclosure. The embodiment of the present application further provides a backlight module 100, which includes a data line 20, a first light-emitting control signal line 30, a second light-emitting control signal line 40, a first scan line 50, a second scan line 60, a third scan line 70, and the light-emitting device driving circuit 10 described above. The data line 20 is used for providing a data signal. The first light emission control signal line 30 is used to provide a first light emission control signal. The second light emission control signal line 40 is for providing 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 refer to the description of the light emitting device driving circuit, and is not described herein again.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a display panel according to an embodiment of the present disclosure. 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, and specific reference may be made to the description of the light emitting device driving circuit 10 above, which is not repeated herein.
The foregoing describes in detail a light emitting device driving circuit, a backlight module and a display panel provided in an embodiment of the present application, and a specific example is applied in the present application to explain the principle and the implementation manner of the present application, and the description of the foregoing embodiment is only used to help understanding the method and the core concept of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (10)
1. A light emitting device driving circuit, comprising:
the light-emitting device is connected in series with a light-emitting loop formed by a first power signal and a second power 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 switched on or switched off based on the first light-emitting control signal;
the second light-emitting control module is connected to a second light-emitting control signal and is connected in series to the light-emitting loop, and the second light-emitting control module is used for controlling the light-emitting loop to be switched on or switched off based on the second light-emitting control signal;
a source of the driving transistor and a drain of the driving transistor are connected in series to the light emitting circuit, a gate of the driving transistor is electrically connected to a first node, a drain of the driving transistor is electrically connected to a second node, and a source of the driving transistor is electrically connected to the first light emitting control module;
the data signal writing module is accessed to 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 transmitting 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 and is electrically connected to the source electrode of the driving transistor and the first node, and the first compensation module 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 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.
2. The circuit of claim 1, further comprising an initialization module, wherein the initialization module is coupled to the first scan signal and the first power signal and electrically connected to the first node, and the initialization module is configured to initialize a potential of the first node under the control of the first scan signal.
3. The light emitting device driving circuit according to claim 2, wherein the initialization module comprises an initialization transistor and a first storage capacitor, a gate of the initialization transistor is coupled to the first scan signal, a source of the initialization transistor is coupled to the first power signal, a drain of the initialization transistor is electrically connected to one end of the first storage capacitor, and another end of the first storage capacitor is electrically connected to the first node.
4. The light emitting device driving circuit according to 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.
5. 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.
6. 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.
7. 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.
8. The light emitting device driving circuit according to claim 1, wherein the second compensation module comprises a second compensation transistor and a second storage capacitor, 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 another end of the second storage capacitor is electrically connected to the first node.
9. 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;
the first scanning line is used for providing a first scanning 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 8, which is connected to the data line, the first light-emission control signal line, the second light-emission control signal line, the first scan line, the second scan line, and the third scan line.
10. A display panel comprising a plurality of pixel units arranged in an array, each of the pixel units comprising the light emitting device driving circuit according to any one of claims 1 to 8.
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