CN115620669A - Pixel driving circuit, driving method and display panel - Google Patents
Pixel driving circuit, driving method and display panel Download PDFInfo
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- CN115620669A CN115620669A CN202110810626.9A CN202110810626A CN115620669A CN 115620669 A CN115620669 A CN 115620669A CN 202110810626 A CN202110810626 A CN 202110810626A CN 115620669 A CN115620669 A CN 115620669A
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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
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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
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0233—Improving the luminance or brightness uniformity across the screen
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Abstract
The application discloses pixel drive circuit, drive method and display panel, wherein, pixel drive circuit adopts 8T2C, includes: the light-emitting diode comprises a driving transistor, a writing sub-circuit, a first storage capacitor, a light-emitting control sub-circuit, a first threshold compensation sub-circuit, a second storage capacitor, a second threshold compensation sub-circuit, a light-emitting control sub-circuit, a first initialization sub-circuit, a second initialization sub-circuit and a light-emitting element, wherein the first threshold compensation sub-circuit is connected with the first storage capacitor and the second storage capacitor, and the second threshold compensation sub-circuit is connected with a control end of the driving transistor and the driving transistor. The pixel driving circuit provided by the embodiment of the application prolongs the writing time of the data voltage by adjusting the writing mode of the data signal, ensures the writing precision and can improve the refresh rate of the panel. The influence of the voltage drop of the power supply voltage end on the display uniformity is eliminated by adjusting the compensation mode of the threshold voltage of the driving transistor, and the pixel driving circuit is suitable for pixel driving of a large-size display panel.
Description
Technical Field
The present disclosure relates generally to the field of display technologies, and in particular, to a pixel driving circuit, a driving method, and a display panel.
Background
In recent years, the AMOLED industry has been rapidly developed at home and abroad due to the excellent display effect of an Active Matrix Organic Light Emitting Diode (AMOLED) display.
In the display process of the flexible AMOLED product, a plurality of Thin Film Transistors (TFTs) and capacitors are required to cooperate together to solve the problem of non-uniform threshold voltage of the TFTs. However, with the continuous development of the display industry, low cost, low power consumption, large size, and high refresh rate gradually become the competitive direction of the display panel.
However, in the prior art, as the display panel is enlarged, the power source terminal V DD Lengthening of the traces results in V DD The voltage drop of the wiring is increased, and the display brightness is not uniform. In addition, when the refresh rate of the display panel is increased, the writing of the signal voltage may be insufficient, which may cause display abnormality.
Disclosure of Invention
In view of the above-mentioned drawbacks and deficiencies of the prior art, it is desirable to provide a pixel driving circuit, a driving method and a display panel, which can realize a low cost, low power consumption, large size and high refresh rate of the display panel.
In a first aspect, the present application provides a pixel driving circuit, comprising: a driving transistor, a write-in sub-circuit, a first storage capacitor, a light emission control sub-circuit, a first threshold compensation sub-circuit, a second storage capacitor, a second threshold compensation sub-circuit, a first initialization sub-circuit, a second initialization sub-circuit, a light emitting element,
the drive transistor is used for controlling the drive current of the light-emitting element;
the first end of the first storage capacitor is electrically connected with a first power supply voltage end;
the writing sub-circuit is used for providing a signal of a data signal input end to the second end of the first storage capacitor under the control of a first scanning signal;
the first threshold compensation sub-circuit is connected with the second end of the first storage capacitor and the first end of the second storage capacitor and used for switching on or off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light-emitting control signal;
the second end of the second storage capacitor is connected with the control end of the driving transistor and used for performing voltage compensation on the driving transistor;
the second threshold compensation sub-circuit is electrically connected with the control end of the driving transistor and the second end of the driving transistor and is used for performing voltage compensation on the control end of the driving transistor under the control of a second scanning signal;
the light-emitting control sub-circuit is electrically connected with the second end of the driving transistor and the light-emitting element and is used for applying the current of the driving transistor to the light-emitting element under the control of the light-emitting control signal;
the first initialization sub-circuit is connected with the first end of the second storage capacitor and is used for resetting the first end of the second storage capacitor under the control of the first scanning signal;
the second initialization sub-circuit is connected with the first end of the light-emitting element and the second end of the second storage capacitor, and is used for applying a signal of a reset voltage end to the first end of the light-emitting element and the second end of the second storage capacitor under the control of a reset signal, and the second end of the light-emitting element is electrically connected with a second power supply voltage end.
Optionally, the second initialization sub-circuit includes a first transistor and a second transistor, a control terminal of the first transistor is connected to the reset signal, a first terminal of the first transistor is connected to the reset voltage terminal, and a second terminal of the first transistor is connected to the control terminal of the driving transistor and a second terminal of the second transistor storage capacitor; the control end of the second transistor is connected with the reset signal, the first end of the second transistor is connected with the reset voltage end, and the second end of the second transistor is connected with the first end of the light-emitting element.
Optionally, the write sub-circuit includes a fourth transistor, a control terminal of the fourth transistor is electrically connected to the first scan signal, a first terminal of the fourth transistor is connected to the data signal input terminal, and a second terminal of the fourth transistor is connected to the second terminal of the first capacitor.
Optionally, the first threshold compensation sub-circuit includes a fifth transistor, a control terminal of the fifth transistor is connected to the light emission control signal, a first terminal of the fifth transistor is connected to the second terminal of the fourth transistor and the second terminal of the first storage capacitor, and a second terminal of the fifth transistor is connected to the first terminal of the second storage capacitor.
Optionally, the second initialization sub-circuit includes a sixth transistor, a control terminal of the sixth transistor is connected to the first scan signal, a first terminal of the sixth transistor is connected to the second terminal of the fifth transistor and the first terminal of the second storage capacitor, and a second terminal of the sixth transistor is grounded.
Optionally, the second threshold compensation sub-circuit includes a seventh transistor, a control terminal of the seventh transistor is connected to the second scan signal, a first terminal of the seventh transistor is connected to the second terminal of the driving transistor, and a second terminal of the seventh transistor is connected to the control terminal of the driving transistor.
Optionally, the light emission control sub-circuit includes an eighth transistor, a control terminal of the eighth transistor is connected to the light emission control signal, a first terminal of the eighth transistor is connected to the second terminal of the driving transistor, and a second terminal of the eighth transistor is connected to the first terminal of the light emitting element.
Optionally, the fourth transistor and the sixth transistor are oxide P-type transistors, and the first transistor, the second transistor, the driving transistor, the fifth transistor, the seventh transistor and the eighth transistor are low-temperature polysilicon N-type transistors.
In a second aspect, the present application provides a driving method of a pixel driving circuit, the driving method including a first stage, a second stage, and a third stage:
in the first stage, the writing sub-circuit writes the data voltage at the data signal input end into the storage capacitor in response to a first scanning signal; the first initialization sub-circuit resets the first end of the first storage capacitor in response to the first scanning signal; the second initialization sub-circuit applies a reset voltage of the initialization signal input terminal to the control terminal of the driving transistor and the first terminal of the light emitting element in response to a reset signal;
in the second stage, the writing sub-circuit responds to the first scanning signal to continuously write the data voltage at the data signal input end into the first storage capacitor; the first initialization sub-circuit responds to the first scanning signal to continuously reset the first end of the second storage capacitor; the second threshold compensation sub-circuit responds to a second scanning signal to enable the second end and the control end of the driving transistor to be conducted, and the first power supply voltage end conducts voltage compensation on the control end of the driving transistor through the second end of the driving transistor until the driving transistor is conducted;
in the third phase, the first threshold compensation sub-circuit responds to a light-emitting signal to conduct the first storage capacitor and the second storage capacitor and write the voltage of the first storage capacitor into the second storage capacitor; the second storage capacitor is used for carrying out voltage compensation on the control end of the driving transistor; the light emission control sub-circuit applies a driving current of the driving transistor to the light emitting element in response to a light emission signal.
In a third aspect, the present application provides a display panel comprising a pixel driving circuit as described in any of the above.
The technical scheme provided by the embodiment of the application can have the following beneficial effects:
the pixel driving circuit provided by the embodiment of the application prolongs the writing time of the data voltage by adjusting the writing mode of the data signal, ensures the writing precision and can improve the refresh rate of the panel. The influence of the voltage drop of the power supply voltage end caused by wiring on the display uniformity is eliminated by adjusting the compensation mode of the threshold voltage of the driving transistor, and the pixel driving circuit is suitable for pixel driving of a large-size display panel.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
fig. 1 is a schematic structural diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 2 is a driving timing diagram of a pixel driving circuit according to an embodiment of the present application;
fig. 3 is a schematic current direction diagram of a pixel driving circuit corresponding to a first stage according to an embodiment of the present disclosure;
fig. 4 is a schematic current direction diagram of a pixel driving circuit corresponding to a second stage according to an embodiment of the present disclosure;
fig. 5 is a schematic current direction diagram of a pixel driving circuit corresponding to a third stage according to an embodiment of the present disclosure;
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.
It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The AMOLED can emit Light by a Thin Film Transistor (TFT) generating a driving current in a saturation state and driving an Organic Light Emitting Diode (OLED) to emit Light, where the luminance of the OLED is proportional to the magnitude of the driving current provided to the OLED device, so that a large driving current is required to achieve an optimal display effect, and since the low temperature polysilicon can provide a high electron mobility, the TFT is made by selecting the low temperature polysilicon more in the AMOLED display technology.
With the gradual maturity of oxide semiconductor manufacturing process in recent years, the oxide TFT is gradually applied to a display panel because it does not need to be crystallized, is simple in manufacturing process, and has a low off-state current, but has a low electron mobility compared to LTPS, and is not suitable for independent application.
According to the technical scheme, the LTPO technology is adopted to combine the two TFTs, so that the high mobility of LTPS is reserved, and the low leakage characteristic of an oxide semiconductor is introduced, so that the display technology becomes a novel display technology. The oxide semiconductor used for display is mostly an N-type semiconductor, the condition that threshold voltages of the oxide TFT and the LTPS TFT are opposite can be utilized, and the oxide TFT and the LTPS TFT can share one grid line by adopting a proper driving circuit structure, so that the power consumption of a system is reduced.
Referring to fig. 1 in detail, the present application provides a pixel driving circuit, including: a driving transistor DN, a writing sub-circuit 1, a first storage capacitor C1, a light-emitting control sub-circuit 2, a first threshold compensation sub-circuit 3, a second storage capacitor C2, a second threshold compensation sub-circuit 4, a first initialization sub-circuit 5, a second initialization sub-circuit 6, and a light-emitting element 7, wherein,
the driving transistor DN is used to control a driving current of the light emitting element.
The first end of the first storage capacitor C1 is electrically connected to a first power supply voltage end.
The write sub-circuit 1 is configured to provide a signal of a data signal input terminal to the second terminal of the first storage capacitor C1 under the control of the first scan signal Gate 1.
The first threshold compensation sub-circuit 3 is connected to the second end of the first storage capacitor C1 and the first end of the second storage capacitor C2, and is configured to turn on or off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light emission control signal; and controlling the first end of the second storage capacitor and the second end of the first storage capacitor to be conducted by a light-emitting control signal, and writing the voltage of the second end of the first storage capacitor into the first end of the second storage capacitor.
A second end of the second storage capacitor C2 is connected to the control end of the driving transistor DN, and is configured to perform voltage compensation on the driving transistor DN; when the second terminal has a voltage, the second storage capacitor can directly apply the voltage of the second terminal to the control terminal of the driving transistor for voltage compensation of the driving transistor.
The second threshold compensation sub-circuit 4 is electrically connected with the control end of the driving transistor DN and the second end of the driving transistor DN, and is configured to perform voltage compensation on the control end of the driving transistor DN under the control of a second scan signal Gate 2; the second threshold compensation sub-circuit may turn on the second terminal and the control terminal of the driving transistor under the control of the second scan signal, and apply a voltage of the second terminal to the control terminal.
The emission control sub-circuit 2 is electrically connected to the second terminal of the driving transistor DN and the light emitting element 7, and is configured to apply a current of the driving transistor DN to the light emitting element 7 under the control of the emission control signal EM.
The first initialization sub-circuit 5 is connected to the first end of the second storage capacitor C2, and is configured to reset the first end of the second storage capacitor C2 under the control of the first scan signal Gate 1.
The second initialization sub-circuit 6 is connected to the first terminal of the light emitting element 7 and the second terminal of the second storage capacitor C2, and is configured to apply a signal of a reset voltage terminal to the first terminal of the light emitting element 7 and the second terminal of the second storage capacitor C2 under the control of a reset signal Rest, and the second terminal of the light emitting element 7 is electrically connected to a second power supply voltage terminal.
The Light Emitting element 7 may be a current-driven Light Emitting device including an LED (Light Emitting Diode) or an OLED (Organic Light Emitting Diode) in the related art, and the OLED is exemplified in the following embodiments. It should be noted that the light emitting element 7 may be various types of OLEDs, such as top emission, bottom emission, double-side emission, and the like, and may emit red light, green light, blue light, white light, and the like, and the embodiment of the present application is not limited thereto.
The "control terminal" specifically refers to a gate of the transistor, the "first terminal" specifically refers to a source of the transistor, and the "second terminal" specifically refers to a drain of the transistor. Of course, those skilled in the art should understand that the "first terminal" and the "second terminal" are interchangeable, that is, the "first terminal" specifically refers to the drain of the transistor, and the "second terminal" specifically refers to the source of the transistor.
First supply voltage terminal V in embodiments of the present application DD For example, an input dc high level signal is held, and the dc high level is referred to as a first voltage; second power supply voltage terminal V SS For example, an input dc low level signal is maintained, which is referred to as a second voltage, lower than the first voltage. The following embodiments are the same and will not be described again.
In addition, transistors can be classified into N-type transistors and P-type transistors according to the semiconductor characteristics of the transistors. When the transistor is used as a switching transistor, the N-type switching transistor is controlled by a high-level switching control signal to be switched on and controlled by a low-level switching control signal to be switched off; the P-type switching transistor is controlled by a low-level switching control signal to be turned on and controlled by a high-level switching control signal to be turned off.
It should be noted that, in the embodiment of the present application, the voltage compensation value of the second storage capacitor to the control terminal of the driving transistor and the voltage compensation value of the second threshold compensation sub-circuit to the control terminal of the driving transistor are not specifically limited, and the mechanisms of the two voltage compensation are different, the voltage compensation of the second storage capacitor to the driving transistor is based on the principle of capacitor bootstrapping, and the voltage of the second storage capacitor is written into the control terminal of the driving transistor, and the second threshold compensation sub-circuit compensates the voltage of the control terminal through the second terminal of the driving transistor.
The two compensation methods are specifically described in the following with reference to specific embodiments.
The second initialization sub-circuit 6 includes a first transistor T1 and a second transistor T2, a control terminal of the first transistor T1 is connected to the reset signal Rest, a first terminal of the first transistor T1 is connected to the reset voltage terminal, and a second terminal of the first transistor T1 is connected to a control terminal of the driving transistor DN and a second terminal of the storage capacitor of the second transistor T2; a control terminal of the second transistor T2 is connected to the reset signal Rest, a first terminal of the second transistor T2 is connected to the reset voltage terminal, and a second terminal of the second transistor T2 is connected to the first terminal of the light emitting element 7.
The write sub-circuit 1 includes a fourth transistor T4, a control terminal of the fourth transistor T4 is electrically connected to the first scan signal Gate1, a first terminal of the fourth transistor T4 is connected to the data signal input terminal, and a second terminal of the fourth transistor T4 is connected to the second terminal of the first capacitor.
The first threshold compensation sub-circuit 3 includes a fifth transistor T5, a control end of the fifth transistor T5 is connected to the emission control signal EM, a first end of the fifth transistor T5 is connected to the second end of the fourth transistor T4 and the second end of the first storage capacitor C1, and a second end of the fifth transistor T5 is connected to the first end of the second storage capacitor C2.
The second initialization sub-circuit 6 includes a sixth transistor T6, a control terminal of the sixth transistor T6 is connected to the first scan signal Gate1, a first terminal of the sixth transistor T6 is connected to the second terminal of the fifth transistor T5 and the first terminal of the second storage capacitor C2, and a second terminal of the sixth transistor T6 is grounded.
The second threshold compensation sub-circuit 4 includes a seventh transistor T7, a control terminal of the seventh transistor T7 is connected to the second scan signal Gate2, a first terminal of the seventh transistor T7 is connected to the second terminal of the driving transistor DN, and a second terminal of the seventh transistor T7 is connected to the control terminal of the driving transistor DN.
The light emitting control sub-circuit 2 includes an eighth transistor T8, a control terminal of the eighth transistor T8 is connected to the light emitting control signal EM, a first terminal of the eighth transistor T8 is connected to the second terminal of the driving transistor DN, and a second terminal of the eighth transistor T8 is connected to the first terminal of the light emitting element 7.
The fourth transistor T4 and the sixth transistor T6 are P-type transistors, and the first transistor T1, the second transistor T2, the driving transistor DN, the fifth transistor T5, the seventh transistor T7, and the eighth transistor T8 are N-type transistors made of low-temperature polysilicon.
A Low Temperature polysilicon thin film transistor (LTPS) uses polysilicon deposition to form an active layer. LTPS has high electron mobility, fast reaction speed, high brightness, high resolution, and low power consumption.
An Oxide thin-film transistor (Oxide TFT) uses, for example, an Oxide semiconductor as an active layer of the TFT, such as Indium Gallium Zinc Oxide (IGZO), and the Oxide semiconductor has a higher electron mobility and a better turn-off characteristic, and compared with LTPS, the Oxide semiconductor has a simple process and a higher compatibility with an amorphous silicon process.
Of course, the oxide thin film transistor may be other metal oxide semiconductors, such as Indium Zinc Tin Oxide (IZTO) or Indium Gallium Zinc Tin Oxide (IGZTO). The oxide thin film transistor can effectively reduce the size of the transistor and prevent leakage current, so that the pixel circuit can be suitable for low-frequency driving, and the resolution of a display panel can be increased.
In order to reduce the power consumption of the OLED, a low-frequency signal may be used to drive the pixel circuit, however, when the pixel circuit is implemented by using all P-type transistors, due to the fact that the leakage current of the P-type transistors is relatively large, the phenomenon of Flicker (Flicker) and the like may be generated by using the low-frequency drive, so that the use of the pixel circuit is limited. In the embodiment of the application, the pixel circuit adopts the pixel circuit of mixed N-type and P-type transistors, and the phenomenon of screen flashing can be overcome when the pixel circuit is used for low-frequency driving. Meanwhile, the N-type transistor has small leakage current, so that the aging problem of the N-type transistor is not required to be considered.
It is defined that the fourth transistor T4, the first storage capacitor C1 and the fifth transistor T5 are connected at a first node N1, the fifth transistor T5, the sixth transistor T6 and the second storage capacitor C2 are connected at a second node N2, and the second storage capacitor C2, the driving transistor DN, the first transistor T1 and the second transistor T2 are connected at a third node N3.
It should be noted that, in the description of the embodiment of the present disclosure, the first node N1, the second node N2, and the third node N3 do not represent actually existing components, but represent junctions of relevant circuit connections in a circuit diagram.
The fourth transistor T4 and the sixth transistor T6 are PMOS transistors, and are turned on when the first scan signal Gate1 is at a low level and turned off when the first scan signal Gate1 is at a high level; the first transistor T1 and the second transistor T2 are NMOS and are switched on when a reset signal Rest is at a high level and switched off when the reset signal Rest is at a low level; the fifth transistor T5 and the eighth transistor T8 are NMOS, and are turned on when the emission control signal EM is at a high level and turned off when it is at a low level; the seventh transistor T7 is an NMOS, and is turned on when the second scan signal Gate2 is at a high level and turned off when it is at a low level.
The application also provides a driving method of the pixel driving circuit, which comprises a first stage T1, a second stage T2 and a third stage T3. The first stage T1, the second stage T2, and the third stage T3 are sequentially generated stages, and the corresponding input timings are as shown in fig. 2.
In the first stage T1, the write-in sub-circuit 1 writes the data voltage at the data signal input terminal into the storage capacitor in response to the first scan signal Gate 1; the first initialization sub-circuit 5 resets the first terminal of the first storage capacitor C1 in response to the first scan signal Gate 1; the second initialization sub-circuit 6 applies a reset voltage of the initialization signal input terminal to the control terminal of the driving transistor DN and the first terminal of the light emitting element 7 in response to the reset signal Rest.
Specifically, rest =0, gate1=1, gate2=1, em =1, the first transistor T1, the second transistor T2, the fourth transistor T4, and the sixth transistor T6 are turned on, and the fifth transistor T5, the seventh transistor T7, and the eighth transistor T8 are turned off. As shown in fig. 3.
The fourth transistor T4 in the write sub-circuit 1 is turned on to apply the voltage V at the data signal input terminal data The first node N1 is written through the fourth transistor T4, and the voltage of the first node N1 is V data 。
The sixth transistor T6 in the first initialization sub-circuit is turned on to initialize the voltage of the second node N2, and the voltage of the second node N2 is 0 at this time.
The first transistor T1 in the second initial sub-circuit is turned on to initialize the reset voltage V at the signal input terminal init Is transmitted to the third node N3, and the voltage of the third node N3 is V init (ii) a The second transistor T2 is turned on to initialize the reset voltage V of the signal input terminal init To the anode of the light emitting element 7, so that the positive charge of the anode is released.
It should be noted that, in the embodiment of the present application, the reset and the data write are implemented in the first stage T1. The driving transistor DN is turned on in this stage, but since the eighth transistor T8 and the seventh transistor T7 are both turned off, there is no current in the driving transistor DN at this time.
In the second stage T2, the write-in sub-circuit 1 responds to the first scan signal Gate1 to continue to write the data voltage at the data signal input terminal into the first storage capacitor C1; the first initialization sub-circuit 5 continues to reset the first end of the second storage capacitor C2 in response to the first scan signal Gate 1; the second threshold compensation sub-circuit 4 responds to a second scanning signal Gate2 to conduct a second end and a control end of the driving transistor DN, and a first power supply voltage end conducts voltage compensation on the control end of the driving transistor DN through the second end of the driving transistor DN until the driving transistor DN is conducted.
Specifically, rest =1, gate1=1, gate2=0, em =1, the fourth transistor T4, the sixth transistor T6, and the seventh transistor T7 are turned on, and the first transistor T1, the second transistor T2, the fifth transistor T5, and the eighth transistor T8 are turned off. In the embodiment of the present application, data writing and voltage compensation are implemented in the second stage T2. As shown in fig. 4.
The fourth transistor T4 in the write sub-circuit 1 is turned on to apply the voltage V at the data signal input terminal data The first node N1 is written through the fourth transistor T4, and the voltage of the first node N1 is V data 。
The sixth transistor T6 in the first initialization sub-circuit is turned on to initialize the voltage of the second node N2, and the voltage of the second node N2 is 0 at this time.
The seventh transistor T7 of the second threshold compensation sub-circuit 4 is turned on to turn on the second terminal and the control terminal of the driving transistor DN, and the voltage V at the first terminal of the driving transistor DN DD Voltage compensation of the third node N3 is performed via the second terminal of the driving transistor DN until the voltage of the third node N3 reaches V DD +V th When the current is cut off, the driving transistor DN is disconnected, and the voltage compensation of the driving transistor DN is realized. Vth is a threshold voltage corresponding to the driving transistor DN.
In the third stage T3, the first threshold compensation sub-circuit 3 responds to a light-emitting signal to conduct the first storage capacitor C1 and the second storage capacitor C2 and write the voltage of the first storage capacitor C1 into the second storage capacitor C2; the second storage capacitor C2 performs voltage compensation on the control end of the driving transistor DN; the light emission control sub-circuit 2 applies a driving current of the driving transistor DN to the light emitting element 7 in response to a light emission signal.
Specifically, rest =1, gate1=0, gate2=1, em =0, the fifth transistor T5 and the eighth transistor T8 are turned on, and the first transistor T1, the second transistor T2, the fourth transistor T4, the sixth transistor T6 and the seventh transistor T7 are turned off. In the embodiment of the present application, light emission and voltage compensation are realized in the third stage T3. As shown in fig. 5.
The fifth transistor T5 in the first threshold compensation sub-circuit 3 is turned on to connect the voltage V of the first node N1 data Transmitted to a second node N2, the second node N2 having a voltage V data The voltage of the third node N3 is V according to the capacitor bootstrap DD +V th +V data The voltage at the first terminal of the driving transistor DN is V DD The driving transistor DN is turned on.
The eighth transistor T8 in the light emission control sub-circuit 2 is turned on, and the driving current of the driving transistor DN is applied to the light emitting element 7 to drive the light emitting element 7 to emit light.
It should be noted that the capacitor bootstrap mainly applies the characteristics of the capacitor, the voltage at two ends of the capacitor cannot change suddenly, and there is always a charging and discharging process to generate the voltage bootstrap and the potential bootstrap. The two-end voltage refers to the voltage of one side of the capacitor relative to the other side of the capacitor, when a certain voltage is kept at the two ends of the capacitor, the voltage of the negative end of the capacitor is increased, the voltage of the positive end is still kept at the original voltage difference of the negative end, and the voltage equal to the voltage of the positive end is lifted by the negative end.
Voltage V of first node N1 data The voltage of the second node N2 is converted into Vdata by the turned-on fifth transistor T5, and the third node N3 is bootstrapped by the voltage V of the second stage T2 DD +V th Is bootstrapped to V DD +V th +V data So the drive transistor DN also remains on at this stage.
The voltages at the nodes of the various stages are shown in the table below.
| First stage T1 | Second stage T2 | Third stage T3 | |
| N1 | V data | V data | V data |
| N2 | 0 | 0 | V data |
| N3 | V init | V DD +V th | V DD +V th +V data |
In the third stage T3, the driving transistor DN works in a saturation state, and according to the current characteristic in the saturation state, the saturation current I flowing through the driving transistor DN and driving the light emitting element 7 to emit light satisfies the formula:
I＝1/2*μ*Cox*W/L*(Vgs-V th ) 2
＝K(V DD +V th +V data –V DD -V th ) 2
＝K(V data ) 2 。
where K is a structural parameter, this number is relatively stable in the same structure and can be calculated as a constant. It can thus be seen that the operating current of the light-emitting element 7 is already not influenced by the threshold voltage V of the drive transistor DN th The influence of (2) is solved, the threshold voltage V of the driving transistor DN caused by the process and long-time operation is solved th Drift, therebyThe display unevenness is improved.
In the embodiment of the present application, the operating current of the light emitting element 7 is not limited by V DD Influence of size, therefore, in the present embodiment, V can be maintained DD And V SS Pull down V under the condition of constant differential pressure DD Such as: v DD The voltage is changed from 4.6V to 3V SS The voltage is changed from-2.4V to-4V, the charging amount of the capacitor is reduced, and the charging time is shortened.
According to the invention, the leakage current of the key position is reduced by introducing the oxide TFT, and simultaneously, one grid line is reduced, so that the power consumption of the display panel is reduced. By adjusting the compensation mode of the threshold voltage of the drive transistor DN, V is eliminated DD The influence of the voltage drop on the display uniformity is suitable for pixel driving of a large-size display panel. By adjusting V data The writing mode prolongs the writing time of the data voltage, ensures the writing precision and can improve the refresh rate of the panel.
In addition, the present application provides a display panel including the pixel driving circuit as described in any one of the above.
The display panel can be applied to any product or component with a display function, such as an OLED display device, an AMOLED display device, a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and is therefore not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Terms such as "disposed" and the like, as used herein, may refer to one element being directly attached to another element or one element being attached to another element through intervening elements. Features described herein in one embodiment may be applied to another embodiment, either alone or in combination with other features, unless the feature is otherwise inapplicable or otherwise stated in the other embodiment.
The present invention has been described in terms of the above embodiments, but it should be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the described embodiments. It will be appreciated by those skilled in the art that many variations and modifications are possible in light of the above teaching and are within the scope of the invention as claimed.
Claims (10)
1. A pixel driving circuit, comprising: a driving transistor, a write-in sub-circuit, a first storage capacitor, a light emission control sub-circuit, a first threshold compensation sub-circuit, a second storage capacitor, a second threshold compensation sub-circuit, a first initialization sub-circuit, a second initialization sub-circuit, a light emitting element,
the driving transistor is used for controlling the driving current of the light-emitting element;
the first end of the first storage capacitor is electrically connected with a first power supply voltage end;
the writing sub-circuit is used for providing a signal of a data signal input end to the second end of the first storage capacitor under the control of a first scanning signal;
the first threshold compensation sub-circuit is connected with the second end of the first storage capacitor and the first end of the second storage capacitor and used for switching on or off the first end of the second storage capacitor and the second end of the first storage capacitor under the control of a light-emitting control signal;
the second end of the second storage capacitor is connected with the control end of the driving transistor and used for performing voltage compensation on the driving transistor;
the second threshold compensation sub-circuit is electrically connected with the control end of the driving transistor and the second end of the driving transistor and is used for performing voltage compensation on the control end of the driving transistor under the control of a second scanning signal;
the light-emitting control sub-circuit is electrically connected with the second end of the driving transistor and the light-emitting element and is used for applying the current of the driving transistor to the light-emitting element under the control of the light-emitting control signal;
the first initialization sub-circuit is connected with the first end of the second storage capacitor and is used for resetting the first end of the second storage capacitor under the control of the first scanning signal;
the second initialization sub-circuit is connected with the first end of the light-emitting element and the second end of the second storage capacitor, and is used for applying a signal of a reset voltage end to the first end of the light-emitting element and the second end of the second storage capacitor under the control of a reset signal, and the second end of the light-emitting element is electrically connected with a second power supply voltage end.
2. The pixel driving circuit according to claim 1, wherein the second initialization sub-circuit comprises a first transistor and a second transistor, a control terminal of the first transistor is connected to the reset signal, a first terminal of the first transistor is connected to the reset voltage terminal, and a second terminal of the first transistor is connected to the control terminal of the driving transistor and a second terminal of the storage capacitor of the second transistor; the control end of the second transistor is connected with the reset signal, the first end of the second transistor is connected with the reset voltage end, and the second end of the second transistor is connected with the first end of the light-emitting element.
3. The pixel driving circuit according to claim 2, wherein the write sub-circuit comprises a fourth transistor, a control terminal of the fourth transistor is electrically connected to the first scan signal, a first terminal of the fourth transistor is connected to the data signal input terminal, and a second terminal of the fourth transistor is connected to the second terminal of the first capacitor.
4. The pixel driving circuit according to claim 3, wherein the first threshold compensation sub-circuit comprises a fifth transistor, a control terminal of the fifth transistor is connected to the light emission control signal, a first terminal of the fifth transistor is connected to the second terminal of the fourth transistor and the second terminal of the first storage capacitor, and a second terminal of the fifth transistor is connected to the first terminal of the second storage capacitor.
5. The pixel driving circuit according to claim 4, wherein the second initialization sub-circuit comprises a sixth transistor, a control terminal of the sixth transistor is connected to the first scan signal, a first terminal of the sixth transistor is connected to the second terminal of the fifth transistor and the first terminal of the second storage capacitor, and a second terminal of the sixth transistor is connected to ground.
6. The pixel driving circuit according to claim 5, wherein the second threshold compensation sub-circuit comprises a seventh transistor, a control terminal of the seventh transistor is connected to the second scan signal, a first terminal of the seventh transistor is connected to the second terminal of the driving transistor, and a second terminal of the seventh transistor is connected to the control terminal of the driving transistor.
7. The pixel driving circuit according to claim 6, wherein the light emission control sub-circuit comprises an eighth transistor, a control terminal of the eighth transistor is connected to the light emission control signal, a first terminal of the eighth transistor is connected to the second terminal of the driving transistor, and a second terminal of the eighth transistor is connected to the first terminal of the light emitting element.
8. The pixel driving circuit according to claim 7, wherein the fourth transistor and the sixth transistor are P-type oxide transistors, and the first transistor, the second transistor, the driving transistor, the fifth transistor, the seventh transistor and the eighth transistor are N-type low temperature polysilicon transistors.
9. A driving method of a pixel driving circuit, the driving method comprising a first stage, a second stage, and a third stage:
in the first stage, the writing sub-circuit writes the data voltage at the data signal input end into the storage capacitor in response to a first scanning signal; the first initialization sub-circuit resets the first end of the first storage capacitor in response to the first scanning signal; the second initializing sub-circuit applies a reset voltage of the initializing signal input terminal to the control terminal of the driving transistor and the first terminal of the light emitting element in response to a reset signal;
in the second stage, the writing sub-circuit responds to the first scanning signal to continuously write the data voltage of the data signal input end into the first storage capacitor; the first initialization sub-circuit responds to the first scanning signal to continuously reset the first end of the second storage capacitor; the second threshold compensation sub-circuit responds to a second scanning signal to enable the second end and the control end of the driving transistor to be conducted, and the first power supply voltage end conducts voltage compensation on the control end of the driving transistor through the second end of the driving transistor until the driving transistor is conducted;
in the third stage, the first threshold compensation sub-circuit responds to a light-emitting signal to conduct the first storage capacitor and the second storage capacitor and write the voltage of the first storage capacitor into the second storage capacitor; the second storage capacitor is used for carrying out voltage compensation on the control end of the driving transistor; the light emission control sub-circuit applies a driving current of the driving transistor to the light emitting element in response to a light emission signal.
10. A display panel comprising the pixel driving circuit according to any one of claims 1 to 8.
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| CN117594008A (en) * | 2023-12-28 | 2024-02-23 | 惠科股份有限公司 | Pixel driving circuit and display device |
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| CN117594008A (en) * | 2023-12-28 | 2024-02-23 | 惠科股份有限公司 | Pixel driving circuit and display device |
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