CN113920923B - 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
- G09G3/22—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 using controlled light sources
- G09G3/30—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 using controlled light sources using electroluminescent panels
- G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
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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
- G09G3/22—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 using controlled light sources
- G09G3/30—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 using controlled light sources using electroluminescent panels
- G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
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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
- G09G3/22—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 using controlled light sources
- G09G3/30—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 using controlled light sources using electroluminescent panels
- G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3225—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
- G09G3/3258—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the voltage across the light-emitting element
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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
- G09G3/22—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 using controlled light sources
- G09G3/30—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 using controlled light sources using electroluminescent panels
- G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3266—Details of drivers for scan electrodes
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 control module, a driving transistor, a data signal writing module, a compensation module, a first storage capacitor and a second storage capacitor. The compensation module is used for compensating the threshold voltage of the driving transistor, and the ratio of the first storage capacitor to the second storage capacitor is 0.25-4, so that the compensation effect of the threshold voltage and the power voltage of the light-emitting device can be improved, and the effect of compensating the final balance state current is achieved.
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, the conventional liquid crystal device belongs to a voltage-driven device, and the organic light emitting diode device belongs to a current-driven device, so that the organic light emitting diode device is sensitive to the electrical variation of the thin film transistor, and the accuracy and uniformity of the picture display are influenced by the uniformity of the threshold voltage of the panel and the threshold voltage drift under bias voltage.
In order to solve the problem of threshold voltage shift, a compensation circuit design is introduced. Large size panels typically employ external compensation schemes, while medium and small size low temperature polysilicon panels typically employ internal compensation schemes. For example, samsung et al generally implement internal compensation of threshold voltage using a 7T1C light emission driving circuit or a 6T1C light emission driving circuit. 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 control module is connected with a control signal and is connected in series with the light-emitting loop, and the control module is used for controlling the light-emitting loop to be switched on or switched off based on the control signal;
the source electrode of the driving transistor and the drain electrode of the driving transistor are connected in series with the light-emitting loop, and the grid electrode of the driving transistor is electrically connected to a first node;
the data signal writing module is accessed to a data signal and a first scanning signal and is electrically connected to a 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 compensation module is connected to a second scanning signal, electrically connected to the source of the driving transistor and the first node, and used for compensating the threshold voltage of the driving transistor under the control of the second scanning signal, wherein the compensation module and the control module are further used for transmitting the first power signal to the first node under the control of the control signal and the second scanning signal;
one end of the first storage capacitor is connected to the first power supply signal, and the other end of the first storage capacitor is electrically connected to the first node; and
and one end of the second storage capacitor is electrically connected to the first node, and the other end of the second storage capacitor is electrically connected to the second node, wherein the ratio of the first storage capacitor to the second storage capacitor is 0.25 to 4.
In the light emitting device driving circuit of the present application, the control module includes a control transistor;
the grid electrode of the control transistor is connected with the control signal, the source electrode of the control transistor is connected with the first power supply signal, and the drain electrode of the control transistor is electrically connected with the source electrode of the driving transistor.
In the light emitting device driving circuit of the present application, the compensation module includes a compensation transistor, a gate of the compensation transistor is connected to the second scan signal, a source of the compensation transistor is electrically connected to a drain of the control transistor, and a drain of the compensation transistor is electrically connected to the first node.
In the light emitting device driving circuit according to 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 control signal, the first scan signal, and the second scan signal correspond to a reset phase, a detection phase, a write phase, and a light emitting phase in sequence;
in the reset stage, the first scanning signal is at a low potential, the second scanning signal is at a high potential, and the control signal is at a high potential;
in the detection stage, the first scanning signal is at a low potential, the second scanning signal is at a high potential, and the control signal is at a low potential;
in the writing stage, the first scanning signal is at a high potential, the second scanning signal is at a low potential, and the control signal is at a low potential;
in the light emitting stage, the first scanning signal is at a low potential, the second scanning signal is at a low potential, and the control signal is at a high potential.
In the light emitting device driving circuit of the present application, in the sensing stage, the calculation formula of the voltage of the first node is V Nst The voltage of the second node is calculated as V + Vth _ oled + Vth _ T1 s VSS + Vth _ oled, where V Nst Is that it isVoltage of the first node, V s VSS is a voltage of the second power signal, Vth _ oled is a threshold voltage of the light emitting device, and Vth _ T1 is a threshold voltage of the driving transistor.
In the light emitting device driving circuit of the present application, in the writing stage, the calculation formula of the voltage of the first node is V Nst VSS + Vth _ oled + Vth _ T1+ C1/(C1+ C2) × (Vdata-VSS-Vth _ oled), and the voltage at the second node is calculated as V s Vdata, wherein V Nst Is the voltage of the first node, V s VSS is a voltage of the second power signal, Vth _ oled is a threshold voltage of the light emitting device, Vth _ T1 is a threshold voltage of the driving transistor, C1 is a capacitor of the first storage capacitor, C2 is a capacitor of the second storage capacitor C2, and Vdata is a voltage of the data signal.
In the light emitting device driving circuit described in the present application, a calculation formula of a current flowing through the light emitting device in the light emitting stage is I oled ＝k*(C2/(C1+C2)*(VSS+Vth_oled-Vdata)) 2 Wherein, I oled In order to obtain a current flowing through the light emitting device, k is mobility of the light emitting device driving circuit, VSS is a voltage of the second power signal, Vth _ oled is a threshold voltage of the light emitting device, C1 is a capacitance of the first storage capacitor, C2 is a capacitance of the second storage capacitor C2, and Vdata is a voltage of the data signal.
The embodiment of the present application further provides a backlight module, including:
a data line for providing a data signal;
a control signal line for providing a control signal;
the first scanning line is used for providing a first scanning signal;
a second scan line for providing a second scan signal; and
the light emitting device driving circuit as described above, which is connected to the data line, the control signal line, the first scan line, and the second scan line.
The embodiment of the application further provides a display panel, the display panel includes a plurality of pixel units arranged in an array, and each pixel unit is 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 control module, a driving transistor, a data signal writing module, a compensation module, a first storage capacitor and a second storage capacitor. The compensation module is used for compensating the threshold voltage of the driving transistor, and the ratio of the first storage capacitor to the second storage capacitor is 0.25-4, so that the compensation effect of the threshold voltage and the power voltage of the light-emitting device can be improved, and the effect of compensating the final balance state current is achieved.
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 light emitting device driving circuit provided in an embodiment of the present application.
Fig. 2 is a circuit schematic diagram of a light emitting device driving circuit provided in an embodiment of the present application.
Fig. 3 is a timing diagram of a light emitting device driving circuit according to an embodiment of the present application.
Fig. 4 is a schematic diagram of a path of a light emitting device driving circuit in a reset stage at the driving timing shown in fig. 3 according to an embodiment of the present disclosure.
Fig. 5 is a schematic path diagram of a pixel driving circuit provided in the embodiment of the present application in a detection stage under the driving timing shown in fig. 3.
Fig. 6 is a schematic path diagram of a write phase of a pixel driving circuit according to an embodiment of the disclosure at the driving timing shown in fig. 3.
Fig. 7 is a schematic path diagram of a light emitting stage of the pixel driving circuit according to the embodiment of the present application at the driving timing shown in fig. 3.
Fig. 8 is a schematic structural diagram of a backlight module according to an embodiment of the present application.
Fig. 9 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 should be apparent that the described embodiments 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 according to an embodiment of the present disclosure. As shown in fig. 1, the light emitting device driving circuit 10 according to the embodiment of the present application includes a light emitting device D, a control module 101, a driving transistor T1, a data signal writing module 102, a compensation module 103, a first storage capacitor C1, and a second storage capacitor C2. 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 control module 101 accesses the control signal En. The control module 101 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 Nst. The data signal writing module 102 accesses the data signal Vdata and the first scanning signal Gn. The data signal writing module 102 is electrically connected to the second node S. The compensation module 103 accesses the second scanning signal Gn-1. The compensation module 103 is electrically connected to the source of the driving transistor T1 and the first node Nst. One end of the first storage capacitor C1 is connected to the first power signal VDD, and the other end of the first storage capacitor C1 is electrically connected to the first node Nst. One end of the second storage capacitor C2 is electrically connected to the first node Nst, and the other end of the second storage capacitor C2 is electrically connected to the second node S.
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 control module 101 is configured to control the light emitting circuit to be turned on or off based on the control signal En. The data signal writing module 102 is configured to transmit a data signal Vdata to the second node S under the control of the first scan signal Gn. The compensation module 103 is used for compensating the threshold voltage of the driving transistor T1 under the control of the second scan signal Gn-1. The compensation module 103 and the control module 101 are further configured to transmit the first power signal VDD to the first node Nst under the control of the control signal En and the second scan signal Gn-1.
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 compensation module 103, so as to prevent the threshold voltage Vth _ T1 of the driving transistor T1 from affecting the current flowing through the light emitting device D, and further improve the accuracy and uniformity of the display panel.
Note that, the current flowing through the light-emitting device D varies from the initial stage of light emission to the stage of reaching the light emission equilibrium state. The variation degree of the current is related to the second power signal VSS and the threshold voltage Vth _ oled of the light emitting device D, and the larger the second power signal VSS and the threshold voltage Vth _ oled of the light emitting device D, the smaller the current. Therefore, by compensating terms related to the second power signal VSS and the threshold voltage Vth _ oled of the light emitting device D in the current formula at the initial stage of light emission, an effect of compensating the final balance current can be achieved.
In one embodiment, the ratio of the first storage capacitor C1 to the second storage capacitor C2 is 0.25 to 4. By increasing the ratio of the first storage capacitor C1 to the second storage capacitor C2, the term related to the second power signal VSS and the threshold voltage Vth _ oled of the light emitting device D can be compensated, so as to achieve the effect of compensating the final balance current, thereby improving the accuracy and uniformity of the display panel.
The smaller the ratio of the first storage capacitor C1 to the second storage capacitor C2, the better the effect of compensating the final balance current. In addition, since the circuit has problems of load and parasitic parameters in the actual display panel, the ratio of the first storage capacitor C1 to the second storage capacitor C2 needs to be greater than or equal to 0.25.
Referring to fig. 2, fig. 2 is a circuit diagram illustrating a first implementation manner of a light emitting device driving circuit according to an embodiment of the present disclosure. As shown in fig. 1 and 2, the control module 101 includes a control transistor T3. The drain of the control transistor T3 is connected to the control signal En, the source of the control transistor T3 is connected to the first power signal VDD, and the drain of the control transistor T3 is electrically connected to the source of the driving transistor T1. The compensation module 103 includes a compensation transistor T4. The gate of the compensation transistor T4 is connected to the second scan signal Gn-1, the source of the compensation transistor T4 is electrically connected to the drain of the control transistor T3, and the drain of the compensation transistor T4 is electrically connected to the first node Nst. The data signal write block 102 includes a data signal write transistor T2. The gate of the data signal writing transistor T2 is connected to the first scan signal Gn, the source of the data signal writing transistor T2 is connected to the data signal Vdata, and the drain of the data signal writing transistor T2 is electrically connected to the second node S.
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 data signal writing transistor T2, the control transistor T3 and the compensating transistor T4 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. 3, fig. 3 is a timing diagram of a driving circuit of a light emitting device according to an embodiment of the present disclosure. The combination of the control signal En, the first scan signal Gn and the second scan signal Gn-1 sequentially corresponds to the reset phase t1, the detection phase t2, the write phase t3 and the emission phase t 4; 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 disclosure includes a reset phase t1, a detection phase t2, a write phase t3, and a light emitting phase t 4.
Note that the light-emitting device D emits light at the light-emission period t 4.
Specifically, in the reset period t1, the first scan signal Gn is at a low potential, the second scan signal Gn-1 is at a high potential, and the control signal En is at a high potential.
Specifically, during the detecting period t2, the first scan signal Gn is low, the second scan signal Gn-1 is high, and the control signal En is low.
Specifically, in the write phase t3, the first scan signal Gn is at a high level, the second scan signal Gn-1 is at a low level, and the control signal En is at a low level.
Specifically, in the light emitting period t4, the first scan signal Gn is at a low potential, the second scan signal Gn-1 is at a low potential, and the control signal En 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. 3 and fig. 4, fig. 4 is a schematic path diagram of a reset stage of the light emitting device driving circuit according to the embodiment of the present disclosure at the driving timing shown in fig. 3.
In the reset phase T1, the second scan signal Gn-1 is at a high level, the compensation transistor T4 is turned on under the control of the high level of the second scan signal Gn-1, the control signal En is at a high level, and the control transistor T3 is turned on under the control of the high level of the control signal En to reset the first node Nst, so that the voltage of the first node Nst is reset to the first power supply signal VDD.
Meanwhile, in the reset period T1, the first scan signal Gn is low, so that the data write transistor T2 is turned off.
Specifically, referring to fig. 3 and 5, fig. 5 is a schematic path diagram of a detection stage of the light emitting device driving circuit provided in the embodiment of the present application under the driving timing shown in fig. 5.
During the detecting period T2, the second scan signal Gn-1 is high, and the compensating transistor T4 is turned on under the control of the high level of the second scan signal Gn-1. In addition, since the potential of the first node Nst is reset to the first power supply signal VDD at the reset stage T1, the driving transistor T1 is turned on.
Wherein, the calculation formula of the voltage of the first node Nst is V Nst VSS + Vth _ oled + Vth _ T1. The voltage at the second node S is calculated as V s VSS + Vth _ oled. Wherein, V Nst Is the voltage of the first node Nst, V s VSS is a voltage of the second node S, VSS is a voltage of the second power signal VSS, Vth _ oled is a threshold voltage of the light emitting device D, and Vth _ T1 is a threshold voltage of the driving transistor T1.
Meanwhile, since the first scan signal Gn is at a low potential, the data write transistor T2 is turned off. The control signal En is low, so that the control transistor T3 is turned off.
Specifically, referring to fig. 3 and fig. 6, fig. 6 is a schematic path diagram of a writing stage of the light emitting device driving circuit provided in the embodiment of the present application at the driving timing shown in fig. 3.
In the write phase T3, the first scan signal Gn is at a high level, and the data signal write transistor T2 is turned on under the control of the high level of the first scan signal Gn to transmit the data signal Vdata to the second node S.
In addition, during the writing period t3, the second scan signal Gn-1 is at a low level, such that the compensation transistor t4 is turned off. The control signal En is low, so that the control transistor T3 is turned off.
Wherein, the calculation formula of the voltage of the first node Nst is V Nst VSS + Vth _ oled + Vth _ T1+ C1/(C1+ C2) × (Vdata-VSS-Vth _ oled). The voltage at the second node S is calculated by V s Vdata. Wherein, V Nst Is the voltage of the first node Nst, V s The voltage of the second node S, VSS, Vth _ oled, Vth _ T1, C1, C2, C2 and Vdata are the voltages of the second power signal VSS, the light emitting device D, the driving transistor T1, the first storage capacitor C1, the data signal Vdata, respectively.
Specifically, referring to fig. 3 and fig. 7, fig. 7 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 at the driving timing shown in fig. 3.
In the light emitting period T4, the control signal En is at a high level, and the control transistor T3 is turned on under the high level control of the control signal En. The calculation formula of the voltage difference T1_ Vgs between the gate and the drain of the driving transistor T1 is as follows:
T1_Vgs＝Vth_T1+C1/(C1+C2)*(Vdata-VSS-Vth_oled)。
here, VSS is a voltage of the second power signal VSS, Vth _ oled is a threshold voltage of the light emitting device D, Vth _ T1 is a threshold voltage of the driving transistor T1, C1 is a capacitance of the first storage capacitor C1, C2 is a capacitance of the second storage capacitor C2, and Vdata is a voltage of the data signal Vdata.
As can be seen from the above, the present invention,i flowing through the light-emitting device D oled The calculation formula of (a) is as follows:
I oled ＝k*(C2/(C1+C2)*(VSS+Vth_oled-Vdata)) 2
where k is the mobility of the light emission driving circuit. By flow through I of the light-emitting device D oled Of the calculation formula, I flowing through the light emitting device D oled The threshold voltage Vth _ T1 of the driving transistor T1 is not related, thereby improving the accuracy and uniformity of the picture display of the display panel.
In addition, by I flowing through the light emitting device D oled It can be seen that by reducing the ratio of the first storage capacitor C1 to the second storage capacitor C2, I flowing through the light emitting device D can be increased oled Therefore, the effect of compensating the final balance current is achieved, and the accuracy and the uniformity of the picture display of the display panel are improved.
Referring to fig. 8, fig. 8 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 control signal line 30, a first scan line 40, a second scan line 50, and the light emitting device driving circuit 10. The data lines 20 are used for providing data signals. The control signal line 30 is used to provide a control signal. The first scan line 40 is used for providing a first scan signal. The second scan signal 50 is used to provide a second scan signal. The light emitting device driving circuit 10 includes a data line 20, a control signal line 30, a first scan line 40, and a second scan line 50. 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. 9, fig. 9 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 above detailed description is made on the light emitting device driving circuit, the backlight module and the display panel provided in the embodiments of the present application, and specific examples are applied herein to explain the principles and embodiments of the present application, and the description of the above embodiments is only used to help understanding the method and the core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (9)
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 signal and the second power signal;
the control module is connected with a control signal and is connected in series with the light-emitting loop, and the control module is used for controlling the light-emitting loop to be switched on or switched off based on the control signal;
the source electrode of the driving transistor and the drain electrode of the driving transistor are connected in series with the light-emitting loop, and the grid electrode of the driving transistor is electrically connected to a first node;
the data signal writing module is accessed to a data signal and a first scanning signal and is electrically connected to a 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;
a compensation module, connected to a second scan signal, and electrically connected to the source of the driving transistor and the first node, the compensation module being configured to compensate a threshold voltage of the driving transistor under the control of the second scan signal, wherein the compensation module and the control module are further configured to transmit the first power signal to the first node under the control of the control signal and the second scan signal;
one end of the first storage capacitor is connected to the first power supply signal, and the other end of the first storage capacitor is electrically connected to the first node; and
one end of the second storage capacitor is electrically connected to the first node, and the other end of the second storage capacitor is electrically connected to the second node, wherein the ratio of the first storage capacitor to the second storage capacitor is 0.25 to 4; wherein the content of the first and second substances,
the control signal, the first scanning signal and the second scanning signal correspond to a reset stage, a detection stage, a write-in stage and a light-emitting stage in sequence;
in the reset stage, the first scanning signal is at a low potential, the second scanning signal is at a high potential, and the control signal is at a high potential;
in the detection stage, the first scanning signal is at a low potential, the second scanning signal is at a high potential, and the control signal is at a low potential;
in the writing stage, the first scanning signal is at a high potential, the second scanning signal is at a low potential, and the control signal is at a low potential;
in the light emitting stage, the first scanning signal is at a low potential, the second scanning signal is at a low potential, and the control signal is at a high potential.
2. The light-emitting device driving circuit according to claim 1, wherein the control module includes a control transistor;
the grid electrode of the control transistor is connected with the control signal, the source electrode of the control transistor is connected with the first power supply signal, and the drain electrode of the control transistor is electrically connected with the source electrode of the driving transistor.
3. The light emitting device driving circuit according to claim 2, wherein the compensation module comprises a compensation transistor, a gate of the compensation transistor is connected to the second scan signal, a source of the compensation transistor is electrically connected to a drain of the control transistor, and a drain of the compensation transistor is electrically connected to the first node.
4. 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 coupled to the first scan signal, a source of the data signal writing transistor is coupled to the data signal, and a drain of the data signal writing transistor is electrically connected to the second node.
5. The circuit of claim 1, wherein during the detection phase, the voltage at the first node is calculated by V Nst VSS + Vth _ oled + Vth _ T1, the voltage of the second node is calculated as V s VSS + Vth _ oled, where V Nst Is the voltage of the first node, V s VSS is a voltage of the second power signal, Vth _ oled is a threshold voltage of the light emitting device, and Vth _ T1 is a threshold voltage of the driving transistor.
6. The light-emitting device drive circuit according to claim 1, wherein a calculation formula of the voltage of the first node in the writing stage is V Nst VSS + Vth _ oled + Vth _ T1+ C1/(C1+ C2) × (Vdata-VSS-Vth _ oled), and the voltage at the second node is calculated as V s Vdata, wherein V Nst Is the voltage of the first node, V s VSS is the voltage of the second node, Vth _ oled is the threshold voltage of the light emitting device, Vth _ T1 is the threshold voltage of the driving transistor, C1 is the capacitance of the first storage capacitor, C2 is the capacitance of the second storage capacitor C2, and Vdata is the voltage of the data signal.
7. The light-emitting device drive circuit according to claim 1, wherein a calculation formula of a current flowing through the light-emitting device in the light-emitting period is I oled ＝k*(C2/(C1+C2)*(VSS+Vth_oled-Vdata)) 2 Therein is disclosedIn (I) oled In order to obtain a current flowing through the light emitting device, k is mobility of the light emitting device driving circuit, VSS is a voltage of the second power signal, Vth _ oled is a threshold voltage of the light emitting device, C1 is a capacitance of the first storage capacitor, C2 is a capacitance of the second storage capacitor C2, and Vdata is a voltage of the data signal.
8. A backlight module, comprising:
a data line for providing a data signal;
a control signal line for providing a control signal;
the first scanning line is used for providing a first scanning signal;
a second scan line for providing a second scan signal; and
the light-emitting device driving circuit according to any one of claims 1 to 7, which is connected to the data line, the control signal line, the first scan line, and the second scan line.
9. 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 7.
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| KR100865394B1 (en) * | 2007-03-02 | 2008-10-24 | 삼성에스디아이 주식회사 | Organic Light Emitting Display |
| CN102654973B (en) * | 2011-08-15 | 2014-11-19 | 京东方科技集团股份有限公司 | Pixel circuit and drive method thereof as well as display panel |
| CN104123912B (en) * | 2014-07-03 | 2016-10-19 | 京东方科技集团股份有限公司 | Image element circuit and driving method, display device |
| KR20170074618A (en) * | 2015-12-22 | 2017-06-30 | 엘지디스플레이 주식회사 | Sub-pixel of organic light emitting display device and organic light emitting display device including the same |
| CN106782331B (en) * | 2016-12-27 | 2023-07-18 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof, display panel and display device |
| CN106981269B (en) * | 2017-06-05 | 2018-12-14 | 京东方科技集团股份有限公司 | A kind of pixel circuit and its driving method, display panel and display device |
| CN109754757B (en) * | 2019-03-28 | 2020-11-06 | 京东方科技集团股份有限公司 | Pixel driving circuit, display device and pixel driving method |
| CN112951164A (en) * | 2021-03-31 | 2021-06-11 | 深圳市华星光电半导体显示技术有限公司 | Pixel driving circuit, display panel and display device |
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