CN112233616A - Pixel driving circuit, display device and driving method - Google Patents

Pixel driving circuit, display device and driving method Download PDF

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Publication number
CN112233616A
CN112233616A CN202011083329.0A CN202011083329A CN112233616A CN 112233616 A CN112233616 A CN 112233616A CN 202011083329 A CN202011083329 A CN 202011083329A CN 112233616 A CN112233616 A CN 112233616A
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transistor
light
emitting element
signal
circuit
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Chinese (zh)
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贾玉虎
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Guangdong Oppo Mobile Telecommunications Corp Ltd
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Guangdong Oppo Mobile Telecommunications Corp Ltd
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Priority to CN202011083329.0A priority Critical patent/CN112233616A/en
Publication of CN112233616A publication Critical patent/CN112233616A/en
Priority to PCT/CN2021/114326 priority patent/WO2022078076A1/en
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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]
    • 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
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • 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
    • G09G2320/0257—Reduction of after-image effects

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

Abstract

The embodiment of the application discloses a pixel driving circuit, a display device and a driving method, wherein the pixel driving circuit comprises: a first transistor, a storage capacitor, a data transmission path, a second transistor, a light emitting element, and a third transistor; the first transistor, is used for making the data signal representing the picture write into the said storage capacitor; the storage capacitor is used for storing the data signal; the data transmission path is used for transmitting the data signal stored by the storage capacitor to the light-emitting element; the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light; the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current; the third transistor is configured to initialize a potential of an anode of the light-emitting element when the second transistor drives the light-emitting element to emit light.

Description

Pixel driving circuit, display device and driving method
Technical Field
The embodiments of the present application relate to electronic technologies, and relate to, but not limited to, a pixel driving circuit, a display device, and a driving method.
Background
At present, electronic devices occupy more and more time in people's work and life, and the improvement of electronic device displays is also becoming a focus of increasing attention. With the development of optical technology and semiconductor technology, displays represented by LCD (Liquid Crystal Display) and OLED (Organic Light Emitting Diode) have the characteristics of lightness, thinness, low energy consumption, fast reaction speed, good color purity, high contrast ratio and the like, and have a leading position in the Display field.
Among them, the OLED display is a display that emits light by electrically exciting a fluorescent organic component and displays an image by driving each organic light emitting cell with a voltage or a current. However, the pixel driving circuit plays a very important role in each organic light emitting unit, and how to design a high-quality and high-performance pixel driving circuit becomes a key point of research for those skilled in the art.
Disclosure of Invention
In view of the above, embodiments of the present application provide a pixel driving circuit, a display device, and a driving method.
The technical scheme of the embodiment of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a pixel driving circuit, where the pixel driving circuit includes: a first transistor, a storage capacitor, a data transmission path, a second transistor, a light emitting element, and a third transistor, wherein:
the first transistor, is used for making the data signal representing the picture write into the said storage capacitor;
the storage capacitor is used for storing the data signal;
the data transmission path is used for transmitting the data signal stored by the storage capacitor to the light-emitting element;
the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light;
the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current;
the third transistor is configured to initialize a potential of an anode of the light-emitting element when the second transistor drives the light-emitting element to emit light.
In a second aspect, embodiments of the present application provide a display device including the pixel driving circuit described above.
In a third aspect, an embodiment of the present application provides a pixel driving method, which is applied to a pixel driving circuit, and the method includes:
writing the acquired data signal representing the image to a storage capacitor of the circuit using a first transistor in the circuit;
transmitting the data signal stored by the storage capacitor to a light-emitting element in the circuit by using a data transmission path in the circuit;
driving the light-emitting element to emit light by a current supplied through a second transistor in the circuit, so that the light-emitting element emits an optical signal corresponding to the data signal;
when the second transistor drives the light-emitting element to emit light, a potential of an anode of the light-emitting element is initialized by a third transistor in the circuit.
The embodiment of the application provides a pixel driving circuit, a display device and a driving method, wherein the pixel driving circuit comprises: a first transistor, a storage capacitor, a data transmission path, a second transistor, a light emitting element, and a third transistor, wherein: the first transistor, is used for making the data signal representing the picture write into the said storage capacitor; the storage capacitor is used for storing the data signal; the data transmission path is used for transmitting the data signal stored by the storage capacitor to the light-emitting element; the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light; the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current; the third transistor is configured to initialize the potential of the anode of the light emitting element when the second transistor drives the light emitting element to emit light, so that the potential of the anode of the light emitting element can be initialized by the third transistor in a data holding stage after the light emitting element is turned on (that is, the light emitting element emits a light signal corresponding to the data signal), thereby improving problems such as screen flicker and smear during low frequency driving.
Drawings
FIG. 1A is a first schematic circuit diagram of a pixel driving circuit in the related art;
FIG. 1B is a first schematic diagram illustrating a working timing sequence of a pixel driving circuit in the related art;
FIG. 2A is a second schematic circuit diagram of a pixel driving circuit in the related art;
FIG. 2B is a diagram illustrating a second operation timing diagram of a pixel driving circuit in the related art;
fig. 3 is a first schematic circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 4 is a second schematic circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
FIG. 5 is a diagram illustrating the luminance variation of the light emitting device of the LTPO pixel driving circuit in the related art;
fig. 6A is a third schematic circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
FIG. 6B is a first schematic diagram illustrating a working timing sequence of the pixel driving circuit according to the embodiment of the present disclosure;
fig. 7A is a schematic diagram of a connection structure of an EOA signal unit according to an embodiment of the present application;
FIG. 7B is a second schematic diagram illustrating a working timing sequence of the pixel driving circuit according to the present embodiment;
FIG. 8 is a schematic diagram illustrating the luminance variation of the light emitting device of the LTPO pixel driving circuit of the present application;
fig. 9 is a schematic flow chart illustrating an implementation of a pixel driving method according to an embodiment of the present application.
Detailed Description
Fig. 1A is a schematic circuit structure diagram of a pixel driving circuit in the related art, as shown in fig. 1A, the pixel driving circuit is a 7T1C (i.e., 7 thin film transistors plus 1 storage capacitor) circuit of LTPS (Low Temperature polysilicon), the 7T1C circuit needs two sets of Gate Driver On Array (GOA) driving circuits, wherein the first scanning signal (Scan1), the second scanning signal (Scan2) and the third scanning signal (Scan3) share 1 set of GOA driving circuits, and the control signal (i.e., em (inversion) signal) uses one set of GOA driving circuits. Since the leakage of the T3 transistor and the T4 transistor in the LTPS driving circuit is large, the pixel circuit cannot well hold the charge of the storage capacitor Cst when the pixel circuit is driven at a low frequency, i.e., the frequency is 1 to 30Hz (hertz), and therefore, the screen body is prone to flicker and other problems caused by brightness variation. The pixel driving circuit shown in fig. 1A can initialize only the G-point, i.e., the gate of the driving transistor T1.
Fig. 1B is a schematic diagram of a first operation timing sequence of the pixel driving circuit in the related art, as shown in fig. 1B, a waveform 11 is a signal waveform diagram of the first Scan signal (Scan1), a waveform 12 is a signal waveform diagram of the second Scan signal (Scan2) and the third Scan signal (Scan3), a waveform 13 is a signal waveform diagram of the control signal (EM), and waveforms of the second Scan signal and the third Scan signal are the same.
Fig. 2A is a schematic circuit diagram of a pixel driving circuit in the related art, and as shown in fig. 2A, the conventional LTPO (Low Temperature Poly Crystalline Silicon and Oxide) pixel driving circuit mainly replaces the T3 Transistor and the T4 Transistor affecting leakage in fig. 1A with Oxide TFT (Thin Film Transistor). That is, the T3 transistor and the T4 transistor in fig. 1A are replaced with LTPS to LTPO (the other transistors remain LTPS, and the connection structure of the circuit remains unchanged) for the purpose of controlling leakage current.
The operation state of the pixel driving circuit shown in fig. 2A is divided into the following three stages. First, initialization stage: the transistor T4 is turned on to initialize the capacitor Cst and to apply an initialization voltage VrefWriting into the lower electrode of the capacitor, at the time of G point potential Vg＝Vref. Second, data writing, threshold voltage compensation and OLED anode initialization stage: the T1 transistor, the T2 transistor, the T3 transistor and the T7 transistor are in an open state, and data signal voltage is written into and the threshold voltage V of the driving tube T1 at the moment is obtainedthAt this time, the potential V at the G pointg＝Vdata+VthPotential V at point Aa＝Vref. Third, luminescence stage: the transistor T1, transistor T5, and transistor T6 are on, the remaining tubes are off, and the OLED emits light.
Fig. 2B is a schematic diagram of a second operation timing sequence of the pixel driving circuit in the related art, as shown in fig. 2B, a waveform 21 is a signal waveform diagram of the first Scan signal (Scan1), a waveform 22 is a signal waveform diagram of the second Scan signal (Scan2), a waveform 23 is a signal waveform diagram of the third Scan signal (Scan3), and a waveform 24 is a signal waveform diagram of the control signal (EM). It can be seen that, when the T3 transistor and the T4 transistor affecting leakage in fig. 1A are replaced with oxide TFTs, the waveforms of the second scan signal and the third scan signal are completely different and are not in timing misalignment. Therefore, compared with the original LTPS pixel driving circuit in fig. 1A, the LTPO pixel driving circuit in fig. 2A needs a new set of GOA driving circuits. That is, three sets of GOA driving circuits are required, the first scanning signal and the second scanning signal share one set of GOA driving circuit, the third scanning signal uses one set of GOA driving circuit, and the EM signal uses one set of GOA driving circuit. Thus, it cannot be guaranteed that the border of the screen body when the LTPO technology is adopted is consistent with the original border of the screen body when the LTPS technology is adopted, and thus the shape, size and the like of the screen body may be affected.
Therefore, the embodiments of the present application provide a pixel driving circuit, which not only introduces LTPO (Low Temperature polysilicon and Oxide) transistors, but also designs a new circuit structure. Thus, the following technical effects can be achieved: (1) the anode of the light emitting element can be initialized in the data holding stage, thereby improving the problems of screen flicker, smear and the like in low-frequency driving. (2) The drain electrode and the grid electrode of the driving tube can be initialized, so that the short-term afterimage problem of the screen body caused by the hysteresis effect of the driving tube is solved. (3) When the LTPO transistor is adopted to ensure that continuous reading of the pixel driving circuit is not fluctuated during low-frequency driving, the driving signal is completely the same as the GOA driving signal of the 7T1C pixel driving circuit of the LTPS in the prior art, so that a new GOA driving circuit is not required to be added, and the frame of the screen body can be kept consistent front and back without being influenced when the LTPO technology is adopted.
The technical solution of the present application is further elaborated below with reference to the drawings and the embodiments. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
In the following description, reference is made to "some embodiments" which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.
In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for the convenience of description of the present application, and have no specific meaning by themselves. Thus, "module", "component" or "unit" may be used mixedly.
It should be noted that the terms "first \ second \ third" referred to in the embodiments of the present application are only used for distinguishing similar objects and do not represent a specific ordering for the objects, and it should be understood that "first \ second \ third" may be interchanged under specific ordering or sequence if allowed, so that the embodiments of the present application described herein can be implemented in other orders than illustrated or described herein.
Fig. 3 is a schematic circuit structure diagram of the pixel driving circuit according to the embodiment of the present invention, and as shown in fig. 3, the pixel driving circuit 300 includes: a first transistor 301, a storage capacitor 302, a data transmission path 303, a second transistor 304, a light emitting element 305, and a third transistor 306, in which:
the first transistor 301 for writing a data signal representing an image into the storage capacitor 302;
the storage capacitor 302 is used for storing the data signal;
the data transmission path 303 is configured to transmit the data signal stored in the storage capacitor 302 to the light emitting element 305;
the second transistor 304 for supplying current to the light emitting element 305 to drive the light emitting element 305 to emit light;
the light emitting element 305 is configured to emit an optical signal corresponding to the data signal under the driving of the current;
here, the light emitting element may be a light emitting diode OLED.
The third transistor 306 is configured to initialize a potential of an anode of the light-emitting element 305 when the second transistor 304 drives the light-emitting element 305 to emit light.
In the pixel driving circuit provided in the embodiment of the present application, the third transistor is configured to initialize the potential of the anode of the light emitting element (i.e., initialize the anode of the light emitting element in the data holding phase) when the second transistor drives the light emitting element to emit light, so that the problems of screen flicker, smear, and the like during low-frequency driving can be improved.
Based on the foregoing embodiments, an embodiment of the present application further provides a pixel driving circuit, where the pixel driving circuit includes: a first transistor, a storage capacitor, a data transmission path, a second transistor, a light emitting element, and a third transistor, wherein:
the first transistor, is used for making the data signal representing the picture write into the said storage capacitor;
a source electrode of the first transistor is connected with a data signal, a grid electrode of the first transistor is connected with a second scanning signal, and a drain electrode of the first transistor is connected with a source electrode of the second transistor;
the storage capacitor is used for storing the data signal;
the data transmission path is used for transmitting the data signal stored by the storage capacitor to the light-emitting element;
the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light;
the grid electrode of the second transistor is connected with the lower electrode of the storage capacitor; the upper electrode of the storage capacitor is connected with a working voltage;
the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current;
the third transistor is configured to initialize a potential of an anode of the light-emitting element when the second transistor drives the light-emitting element to emit light;
a source electrode of the third transistor is connected with a reference signal, a grid electrode of the third transistor is connected with a control signal, and a drain electrode of the third transistor is connected with an anode electrode of the light-emitting element; the cathode of the light-emitting element is connected to the voltage of the ground terminal;
here, the third transistor has a source connected to a reference signal and a drain connected to an anode of a light emitting element, so that an anode potential of the light emitting element can be initialized.
The second scanning signal is used for controlling the switch of the first transistor to write the data signal line by line, the reference signal is used for potential initialization, and the control signal is used for controlling the working state of the light-emitting element.
Based on the foregoing embodiments, an embodiment of the present application further provides a pixel driving circuit, where the pixel driving circuit includes: a first transistor, a storage capacitor, a second transistor, a light-emitting element, a third transistor, a fifth transistor, and a sixth transistor, wherein:
the first transistor, is used for making the data signal representing the picture write into the said storage capacitor;
a source electrode of the first transistor is connected with a data signal, a grid electrode of the first transistor is connected with a second scanning signal, and a drain electrode of the first transistor is connected with a source electrode of the second transistor;
the storage capacitor is used for storing the data signal;
the fifth transistor and the sixth transistor are configured to switch the light emitting element between different operating states, where the different operating states include an on state and an off state, and transmit a data signal in the storage capacitor to the light emitting element when the light emitting element is in the on state;
the drain electrode of the fifth transistor is connected with the source electrode of the second transistor, the grid electrode of the fifth transistor is connected with a control signal, and the source electrode of the fifth transistor is connected with a working voltage;
a source of the sixth transistor is connected to a drain of the second transistor, a gate of the sixth transistor is connected to the control signal, and a drain of the sixth transistor is connected to an anode of the light-emitting element;
here, the fifth transistor and the sixth transistor together form the data transmission path for switching the light emitting element between different operation states by the control signal, and transmitting the data signal in the storage capacitor to the light emitting element when the light emitting element is in an on state.
The second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light;
the grid electrode of the second transistor is connected with the lower electrode of the storage capacitor; the upper electrode of the storage capacitor is connected with a working voltage;
the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current;
the third transistor is configured to initialize a potential of an anode of the light-emitting element when the second transistor drives the light-emitting element to emit light;
a source electrode of the third transistor is connected with a reference signal, a grid electrode of the third transistor is connected with a control signal, and a drain electrode of the third transistor is connected with an anode electrode of the light-emitting element; the cathode of the light-emitting element is connected to the voltage of the ground terminal;
the second scanning signal is used for controlling the switch of the first transistor to write the data signal line by line, the reference signal is used for potential initialization, and the control signal is used for controlling the working state of the light-emitting element.
Based on the foregoing embodiments, an embodiment of the present application further provides a pixel driving circuit, where the pixel driving circuit includes: a first transistor, a storage capacitor, a second transistor, a light-emitting element, a third transistor, a fourth transistor, a fifth transistor, and a sixth transistor, wherein:
the first transistor, is used for making the data signal representing the picture write into the said storage capacitor;
a source electrode of the first transistor is connected with a data signal, a grid electrode of the first transistor is connected with a second scanning signal, and a drain electrode of the first transistor is connected with a source electrode of the second transistor;
the storage capacitor is used for storing the data signal;
the fourth transistor is used for initializing the potentials of a drain electrode and a grid electrode of the second transistor;
a grid electrode of the fourth transistor is connected with a first scanning signal, a source electrode of the fourth transistor is connected with the reference signal, and a drain electrode of the fourth transistor is connected with a drain electrode of the second transistor;
here, the gate of the fourth transistor is connected to the first scan signal, the source of the fourth transistor is connected to the reference signal, and the drain of the fourth transistor is connected to the drain of the second transistor, so as to initialize the potentials of the drain and the gate of the second transistor (i.e., the drain and the gate of the driving transistor are both initialized by the fourth transistor, so that the voltage between the drain and the gate of the driving transistor is zero), thereby achieving the technical effect of improving the short-term image retention problem of the panel due to the hysteresis effect of the driving transistor (i.e., the second transistor).
The fifth transistor and the sixth transistor are configured to switch the light emitting element between different operating states, where the different operating states include an on state and an off state, and transmit a data signal in the storage capacitor to the light emitting element when the light emitting element is in the on state;
here, the state of the light emitting element includes an on state, an off state, a saturation state, and the like.
The drain electrode of the fifth transistor is connected with the source electrode of the second transistor, the grid electrode of the fifth transistor is connected with a control signal, and the source electrode of the fifth transistor is connected with a working voltage;
a source of the sixth transistor is connected to a drain of the second transistor, a gate of the sixth transistor is connected to the control signal, and a drain of the sixth transistor is connected to an anode of the light-emitting element;
the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light;
the grid electrode of the second transistor is connected with the lower electrode of the storage capacitor; the upper electrode of the storage capacitor is connected with a working voltage;
the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current;
a potential initialization unit configured to initialize a potential of an anode of the light emitting element when the second transistor drives the light emitting element to emit light;
a source electrode of the third transistor is connected with a reference signal, a grid electrode of the third transistor is connected with a control signal, and a drain electrode of the third transistor is connected with an anode electrode of the light-emitting element; the cathode of the light-emitting element is connected to the voltage of the ground terminal;
the first scanning signal is used for controlling the switch of the fourth transistor so as to write the reference signal row by row; the second scanning signal is used for controlling the switch of the first transistor so as to write the data signal line by line; the reference signal is used for potential initialization; the control signal is used for controlling the working state of the light-emitting element.
In an embodiment of the present application, the first scan signal, the second scan signal, and the third scan signal are row selection signals.
Based on the foregoing embodiments, an embodiment of the present application further provides a pixel driving circuit, and fig. 4 is a second schematic circuit structure diagram of the pixel driving circuit according to the embodiment of the present application, as shown in fig. 4, the pixel driving circuit 400 includes: a first transistor 401, a storage capacitor 402, a second transistor 403, a light-emitting element 404, a third transistor 405, a fourth transistor 406, a fifth transistor 407, a sixth transistor 408, and a seventh transistor 409, in which:
the first transistor 401 for writing a data signal representing an image into the storage capacitor 402;
a source of the first transistor 401 is connected to a data signal, a gate of the first transistor 401 is connected to a second scan signal, and a drain of the first transistor 401 is connected to a source of the second transistor 403;
the storage capacitor 402 is used for storing the data signal;
the fourth transistor 406 is configured to initialize the potentials of the drain and the gate of the second transistor 403;
the gate of the fourth transistor 406 is connected to a first scan signal, the source of the fourth transistor 406 is connected to the reference signal, and the drain of the fourth transistor 406 is connected to the drain of the second transistor 403;
here, the fourth transistor is collocated with the seventh transistor so that the potentials of the gate and the drain of the second transistor are initialized.
The fifth transistor 407 and the sixth transistor 408 are configured to switch the light emitting element 404 between different operating states, which include an on state and an off state, wherein when the light emitting element 404 is in the on state, the data signal in the storage capacitor 402 is transmitted to the light emitting element 404;
the drain of the fifth transistor 407 is connected to the source of the second transistor 403, the gate of the fifth transistor 407 is connected to a control signal, and the source of the fifth transistor 407 is connected to a working voltage;
a source of the sixth transistor 408 is connected to a drain of the second transistor 403, a gate of the sixth transistor 408 is connected to the control signal, and a drain of the sixth transistor 408 is connected to an anode of the light emitting element 404;
the second transistor 403 is used for supplying current to the light-emitting element 404 to drive the light-emitting element 404 to emit light;
the gate of the second transistor 403 is connected to the lower electrode of the storage capacitor 402; the upper electrode of the storage capacitor 402 is connected with a working voltage;
the light-emitting element 404 is configured to emit an optical signal corresponding to the data signal under the driving of the current;
the third transistor 405 is configured to initialize a potential of an anode of the light-emitting element 404 when the second transistor 403 drives the light-emitting element 404 to emit light;
a source of the third transistor 405 is connected to a reference signal, a gate of the third transistor 405 is connected to a control signal, and a drain of the third transistor 405 is connected to an anode of the light-emitting element 404; the cathode of the light-emitting element 404 is connected to the ground voltage;
the seventh transistor 409 for compensating for a deviation of the threshold voltage of the second transistor 403;
the drain of the seventh transistor 409 is connected to the gate of the second transistor 403, the gate of the seventh transistor 409 is connected to a third scan signal, and the source of the seventh transistor 409 is connected to the drain of the second transistor 403;
the first scanning signal is used for controlling the switch of the fourth transistor so as to write the reference signal row by row; the second scanning signal is used for controlling the switch of the first transistor so as to write the data signal line by line; the third scan signal is used to control the switching of the seventh transistor. The first scanning signal, the second scanning signal and the third scanning signal are all line selection signals; the reference signal is used for potential initialization, and the control signal is used for controlling the working state of the light-emitting element.
Here, in the pixel driving circuit provided in the embodiment of the present application, the pulse widths of the first scanning signal and the second scanning signal are the same, but there is a timing shift relationship. Therefore, the same GOA driving signal can be used for the first and second scan signals. The pulse width of the third scanning signal is the same as that of the control signal, and only a time sequence dislocation relation exists. Therefore, the same GOA driving signal can be used for the third scan signal and the control signal. That is, only two sets of GOA driving circuits are needed, so that the driving signals of the pixel driving circuit in the embodiment of the present application are completely the same as the GOA driving signals of the 7T1C pixel driving circuit of LTPS in the prior art, and therefore, no new GOA driving circuit needs to be added, thereby ensuring that the frame of the screen body can be kept consistent front and back without being affected when the LTPO technology is adopted.
In some embodiments, the first transistor, the second transistor, the fourth transistor, the fifth transistor and the sixth transistor in the circuit are low temperature polysilicon LTPS thin film transistors; the third transistor and the seventh transistor are low-temperature polysilicon and oxide LTPO thin film transistors.
Here, the first transistor, the second transistor, the fourth transistor, the fifth transistor, and the sixth transistor are low-temperature polysilicon LTPS thin film transistors of PMOS, so that the operation states of the first transistor, the second transistor, the fourth transistor, the fifth transistor, and the sixth transistor are all active at low level. The third transistor and the seventh transistor are both low-temperature polysilicon and oxide LTPO thin film transistors of NMOS, so that the working states of the third transistor and the seventh transistor are high-level effective.
According to the pixel driving circuit provided by the embodiment of the application, the third transistor and the seventh transistor are LTPO thin film transistors, and other transistors are LTPS thin film transistors, so that continuous reading of the pixel driving circuit during low-frequency driving can be ensured to be free from fluctuation. That is, the problem that the pixel circuit in the prior art cannot well maintain the charge of the storage capacitor Cst when the pixel circuit is driven at a low frequency, that is, the frequency is 1 to 30Hz (hertz), so that the screen body is prone to flicker caused by brightness change, and the like, is solved.
How to reduce the power consumption of a mobile phone display screen has become a hot point of research in the industry at present, the LTPO technology has been applied to a part of wearable products as one implementation mode, and the LTPO technology is a technology for integrating two TFTs together by utilizing the advantages of high mobility of LTPS and low leakage of oxide TFTs. The LTPO pixel driving circuit in the prior art, that is, the LTPO pixel driving circuit shown in fig. 2A, has not only the problem that a new set of GOA driving circuit needs to be added, but also the following defects:
fig. 5 is a schematic diagram illustrating the luminance variation of the light emitting element of the LTPO pixel driving circuit in the related art, and as shown in fig. 5, a curve 51 is a variation curve of the luminance of the OLED with time in a state where the EM signal is continuously turned on and off in the data refresh period, and a curve 52 is a variation curve of the luminance of the OLED with time in a state where the EM signal is continuously turned on and off in the data hold period. In the case where the pixel driving circuit shown in fig. 2A is driven at a low frequency, when the pixel driving circuit is in a data refresh stage, the GOA driving signal and the EOA (Array EM signal driving) driving signal operate simultaneously, and the anode potential of the OLED can be initialized. When the pixel driving circuit is in a data holding stage, the anode point A of the OLED is not initialized due to only EOA action, and at the moment, if the EM signal is turned off, the brightness of the OLED is increased to cause the increase of average brightness, so that human eyes observe phenomena such as screen flicker, smear and the like.
TABLE 1 working states of GOA and EOA signals of LTPO pixel driving circuit in related art
Phases Data refresh phase Data retention phase
GOA signal Movement of Do not act
EOA signal Movement of Movement of
OLED anode point A initialization Is that Whether or not
The three phases of operation of the pixel driving circuit (i.e. initialization phase; data write, threshold voltage compensation, and OLED anode initialization phase; light emission phase) belong to the data refresh phase in fig. 5. As shown in table 1, the GOA signal and the EOA signal are both active during the data refresh phase, so that the OLED anode a is initialized, and the brightness of the OLED also changes normally with the switching of the EM signal during the data refresh phase. However, in the data holding phase, only the EOA signal is active and the GOA signal is inactive, so that the anode a point of the OLED is not initialized, and thus, in the data holding phase, the OLED has a problem of increasing average brightness along with the switching of the EM signal, which may cause problems of screen flicker, smear, and the like. The GOA includes Scan1, Scan2, Scan3, and other signals, and initializes and writes signal units for controlling the internal compensation circuit. The EOA includes an EM signal, a signal element that controls the emission of the OLED.
Therefore, based on the foregoing embodiments, the present application provides a new LTPO pixel driving circuit, which is compatible with the current GOA driving signal of LTPS without adding a new GOA driving circuit, so as to ensure that the frame of the screen is not affected when the LTPO technology is used. In addition, the circuit can effectively initialize the driving tube and the anode of the OLED, thereby solving the problems of flicker, short-term afterimage, smear and the like of the LTPO pixel driving circuit in the prior art during low-frequency driving. Fig. 6A is a schematic circuit structure diagram of a pixel driving circuit according to an embodiment of the present invention, and as shown in fig. 6A, the T3 transistor and the T7 transistor are Oxide TFTs (i.e., LTPO), and the remaining transistors (i.e., the T1 transistor, the T2 transistor, the T4 transistor, the T5 transistor, and the T6 transistor) are all PMOS (P-Channel Metal Oxide Semiconductor, P-Channel enhancement mode field effect transistor) TFTs in LTPS. The T1 tube is a switch tube and is mainly used for writing data signals. The T2 tube is a driving tube and is mainly used for controlling the lighting state of the OLED device. The T3 tube is a switching tube and is an NMOS (N-Metal-Oxide-Semiconductor) device of an IGZO (Indium Gallium Zinc Oxide), and is mainly used for controlling initialization of an anode potential of the OLED. The T4 transistor is a switch transistor and is mainly used to control the initialization of the lower electrode potential of the storage capacitor Cst in cooperation with the T7 transistor. The T5 tube and the T6 tube are switching tubes and are mainly used for controlling whether the OLED device is lightened or not. The T7 tube is a switch tube and is an NMOS device of IGZO, and is mainly used for controlling the writing of the data compensation signal. The storage capacitor Cst is mainly used for storing a data signal. Since the TFT connected to the capacitor and the TFT connected to the light emitting element are replaced with an oxide TFT (i.e., LTPO) having a lower leakage current, a leakage path of the pixel driving circuit can be effectively reduced. Moreover, the Scan1 signal and the Scan2 signal share one set of driving circuit, and the Scan3 signal and the EM signal share one set of driving circuit, i.e. a new GOA driving circuit is not required to be added.
The operation state of the pixel driving circuit shown in fig. 6A during data refresh can be divided into the following three stages:
(1) capacitor and led anode initialization stage: the T3, T4, and T7 transistors are on and the other transistors are off. Initializing the lower electrode of the capacitor Cst and the anode of the light emitting diode OLED, i.e. the initialization voltage VrefAnd writing the lower electrode of the capacitor Cst and the anode of the light emitting diode OLED. At this time, the potential V of G pointg＝VrefPotential V at point Aa＝VrefAnd D point potential Vd＝VrefThus V of T2 pipegdWhen the voltage between the gate and the drain of the T2 transistor is zero, the initialization process can be performed on the driving transistor T2.
(2) Data write, threshold voltageCompensation and anode initialization stage: the T1, T2, T3 and T7 transistors are on and the other transistors are off. The data signal voltage VdataWriting and acquiring the threshold voltage V of the driving tube T2 at the momentthAt this time, the potential V at the G pointg＝Vdata+VthThat is, at this time, the deviation of the threshold voltage of the driving tube T2 is compensated. At the same time, reset the point A, at which the potential V of the point A isa＝Vref。
(3) A light emitting stage: the T2, T5, and T6 transistors are on and the other transistors are off. At this time, the light emitting diode OLED is controlled to emit light, and the current for driving the OLED to emit light satisfies the following formula: i isoled＝1/2K*(Vdd-Vdata)2. Wherein, the IoledThe current for driving the light emitting diode OLED to emit light, VddIs the voltage corresponding to ELVDD in FIG. 6A, said VdataIs the Data signal voltage, i.e., the input voltage of the Data input port Data. K is obtained from the formula K ═ μ × Cox — W/L, where μ is the offset ratio of the T1 tube, Cox is the capacitance per unit area of the storage capacitor Cst, W is the width of the T1 tube, and L is the length of the T1 tube.
The working state of the pixel driving circuit shown in fig. 6A during data retention includes:
(1) and (3) low-frequency compensation stage: the Scan1 signal, the Scan2 signal, and the Scan3 signal are off (i.e., the Scan1 signal, the Scan2 signal, and the Scan3 signal are in the inactive state) and the EM signal is on (the EM signal is in the active state). Initializing the point A, namely the anode of the OLED when the OLED is driven to be lighteda＝Vref。
That is to say, in the LTPO pixel driving circuit in the embodiment of the present application, when the EM signal in the data holding phase is turned off, the T3 transistor is turned on to reset the anode, so as to ensure that the brightness does not increase in the data holding phase of the low-frequency driving, and thus, the problems of screen flicker, smear, and the like do not occur.
Fig. 6B is a schematic diagram of an operation timing sequence of the pixel driving circuit according to the embodiment of the present invention, where the operation timing sequence is an operation timing sequence of the pixel driving circuit in a data refresh stage, as shown in fig. 6B, a waveform 61 is a signal waveform diagram of the first Scan signal (Scan1), a waveform 62 is a signal waveform diagram of the second Scan signal (Scan2), a waveform 63 is a signal waveform diagram of the third Scan signal (Scan3), and a waveform 64 is a signal waveform diagram of the control signal (EM signal). It can be seen that the Scan1 signal and the Scan2 signal have the same waveform width and are only in a timing offset relationship. The Scan3 signal and the EM signal have the same waveform width and are only in a timing offset relationship, so the Scan1 signal and the Scan2 signal can share one set of GOA driving circuits, and the Scan3 signal and the EM signal can share one set of GOA driving circuits. Thus, the operation timing (i.e., the driving timing) of the pixel driving circuit in the embodiment of the present application can be kept consistent with the operation timing of the 7T1C pixel driving circuit of LTPS in the related art. That is, the GOA driving circuits corresponding to the 7T1C pixel driving circuits of the conventional LTPS can be kept identical in the pixel driving circuits.
Fig. 7A is a schematic diagram of a connection structure of an EOA signal unit according to an embodiment of the present application, and as shown in fig. 7A, the display device may include a plurality of EOA units, and the plurality of EOA units correspond to a shift register. The ESTV is a start signal, the first EOA unit 701 starts to operate under the trigger of the ESTV signal, the output signal of the first EOA unit 701 is used for triggering the second EOA unit 702 to operate, and the output signal of the second EOA unit 702 is used for triggering the third EOA unit 703 to operate. Meanwhile, the Scan3 signal and the EOA signal (i.e., the EM signal) share a circuit, and a signal (i.e., an output signal) output by the circuit can be used by the EM signal terminal and the Scan3 signal terminal. As shown in fig. 7A, a TFT 705 (corresponding to a switch) is connected to each Scan3 signal terminal 704, and each EOA cell includes a Scan3 signal terminal 704 and an EM signal terminal 706. The TFT 705 is turned on and the Scan3 signal terminal 704 and EM signal terminal 706 may use this output signal together. The TFT 705 is turned off and the output signal is only applied to the Scan3 signal terminal 704 or only to the EM signal terminal 706. The Scan3 control signal is a signal for controlling the switching of the TFT 705 tube, and the Scan3 control signal is different from the Scan3 signal.
Fig. 7B is a schematic diagram of an operating timing sequence of the pixel driving circuit according to the embodiment of the present invention, where the operating timing sequence is an operating timing sequence of the pixel driving circuit in a data refreshing stage and a data holding stage, as shown in fig. 7B, a waveform 71 is a signal waveform diagram of a Scan3 control signal, and a waveform 72 is a signal waveform diagram of an EOA signal (i.e., an EM signal), where the Scan3 control signal is turned on only during data refreshing, and the Scan3 control signal is turned off during the data holding stage.
Fig. 8 is a schematic diagram illustrating the luminance variation of the light emitting element of the LTPO pixel driving circuit according to the embodiment of the present invention, as shown in fig. 8, a curve 81 is a variation curve of the luminance of the OLED with time in a state where the EM signal is continuously turned on and off in the data refresh period, and a curve 82 is a variation curve of the luminance of the OLED with time in a state where the EM signal is continuously turned on and off in the data hold period. In the case where the pixel driving circuit shown in fig. 6A is driven at a low frequency, when the pixel driving circuit is in the data refresh stage, the GOA driving signal and the EOA driving signal operate simultaneously, and the anode potential of the OLED can be initialized. When the pixel driving circuit is in a data holding stage, under the condition that only an EOA signal acts and a GOA signal does not act, the anode A point of the OLED can still be initialized, so that the problems that the average brightness is increased due to the fact that the brightness of the OLED is increased if an EM signal is turned off, and therefore human eyes observe screen flicker, smear and the like can be solved.
TABLE 2 working states of GOA and EOA signals of LTPO pixel driving circuit of the present application
Phases Data refresh phase Data retention phase
GOA signal Movement of Do not act
EOA signal Movement of Movement of
OLED anode point A initialization Is that Is that
The three phases of the pixel driving circuit (i.e. capacitor and led anode initialization phase; data writing, threshold voltage compensation and anode initialization phase; light emission phase) belong to the data refresh phase in fig. 8. As shown in table 2, the GOA signal and the EOA signal are both active during the data refresh phase, so that the OLED anode a is initialized, and the brightness of the OLED also changes normally with the switching of the EM signal during the data refresh phase. In addition, in the data holding stage, the anode point a of the OLED is initialized under the condition that only the EOA signal is activated and the GOA signal is not activated, so that the brightness of the OLED also normally changes along with the on and off of the EM signal in the data holding stage, and the problem of the increase of the average brightness is avoided. Thereby avoiding the problems of screen flicker, smear and the like.
The embodiment of the application provides a new LTPO pixel driving circuit, the GOA driving signal of the circuit is completely the same as that of the current LTPS 7T1C pixel driving circuit, therefore, a new GOA driving circuit does not need to be added, the frame of a screen body is ensured to be consistent with the driving screen body of the LTPS without being influenced when the LTPO technology is adopted, in addition, when the pixel driving circuit is adopted, the grid of a driving tube T2 and the anode of an OLED (light emitting diode) can be initialized, and the problems of flicker, smear, short-term residual image and the like of the LTPO screen body under low frequency or frequency cut are effectively improved.
TABLE 3 comparison of LTPO circuits in the examples of the present application with LTPO circuits of the related art
Figure BDA0002719483100000181
The embodiment of the application provides a brand-new LTPO driving circuit, which can initialize the driving tube T2 and the anode of the light-emitting element, so as to effectively improve the problems of flickering, smear, short-term afterimage and the like of an LTPO screen body under low frequency or cut-off frequency. As can be seen from table 3, the LTPO circuit in the related art (i.e., the circuit shown in fig. 2A) just initializes the gate of the driving transistor, cannot fully utilize the off time of the EM signal, and has two leakage paths of the T3 transistor and the T4 transistor, and requires three sets of GOA driving circuits, which increases the frame of the panel. The LTPO circuit (i.e., the circuit shown in fig. 6A) in the embodiment of the present application can initialize not only the gate of the driving transistor but also the drain of the driving transistor, so that the voltage difference between the gate and the drain of the driving transistor is zero, thereby optimizing the hysteresis effect of the device, and significantly improving the problems of short-term image retention, smear, and the like. Meanwhile, the initialization action of the anode of the light-emitting element can be synchronously carried out during the period of turning off the EM signal, so that the low-frequency flicker phenomenon is obviously improved. The leakage path is reduced to only one leakage path through the T7 transistor, and the pixel driving circuit only needs two sets of GOA driving circuits, which is the same as the conventional LTPS pixel driving circuit.
Based on the foregoing embodiments, embodiments of the present application provide a display device including the pixel driving circuit described above.
Based on the foregoing embodiments, an embodiment of the present application provides a pixel driving method, where the pixel driving method is applied to the pixel driving circuit, and fig. 9 is a schematic diagram of an implementation flow of the pixel driving method according to the embodiment of the present application, and as shown in fig. 9, the method includes:
step S901 of writing the acquired data signal representing the image into a storage capacitor of the circuit by using a first transistor in the circuit;
step S902, transmitting the data signal stored in the storage capacitor to the light emitting element in the circuit by using the data transmission path in the circuit;
step S903, driving the light emitting element to emit light through a current provided by a second transistor in the circuit, so that the light emitting element emits an optical signal corresponding to the data signal;
in step S904, when the light-emitting element is driven to emit light by the second transistor, a potential of an anode of the light-emitting element is initialized by a third transistor in the circuit.
In the embodiment of the application, the acquired data signal representing the image is written into the storage capacitor of the circuit by utilizing the first transistor in the circuit; transmitting the data signal stored by the storage capacitor to a light-emitting element in the circuit by using a data transmission path in the circuit; driving the light-emitting element to emit light by a current supplied through a second transistor in the circuit, so that the light-emitting element emits an optical signal corresponding to the data signal; when the second transistor drives the light-emitting element to emit light, the potential of the anode of the light-emitting element is initialized by the third transistor in the circuit, so that the potential of the anode of the light-emitting element can be initialized by the third transistor in a data holding stage after the light-emitting element is turned on (that is, the light-emitting element emits a light signal corresponding to the data signal), and the problems of screen flicker, smear and the like during low-frequency driving can be solved.
Based on the foregoing embodiments, an embodiment of the present application further provides a pixel driving method, where the pixel driving method is applied to the pixel driving circuit, and the method includes:
step S911, applying a voltage smaller than a first preset value to the first scan signal, applying a voltage larger than a second preset value to the control signal, and applying a voltage larger than the first preset value to the third scan signal, so that the third transistor, the fourth transistor, and the seventh transistor are in an on state;
here, the fourth transistor is a LTPS of PMOS, and the operation state is active low, so that the fourth transistor is in an on state when a voltage smaller than a first preset value is applied to the first scan signal. The third transistor and the seventh transistor are LTPO of NMOS and active in high level, so that the third transistor is turned on when a voltage greater than a second preset value is applied to the control signal, and the seventh transistor is turned on when a voltage greater than the first preset value is applied to the third scan signal. Of course, it is also necessary to apply a voltage greater than the first preset value to the second scan signal to turn off the first transistor. The second transistor, the fifth transistor and the sixth transistor are LTPS of PMOS, the working state is effective at low level, and further the second transistor, the fifth transistor and the sixth transistor are in a closed state under the action of the control signal.
Step S912, writing a reference signal into the lower electrode of the storage capacitor and the drain of the second transistor by using the fourth transistor and the seventh transistor, so that a voltage corresponding to a gate potential of the second transistor is a voltage corresponding to the reference signal, and a voltage corresponding to a drain potential of the second transistor is a voltage corresponding to the reference signal;
step S913 of transmitting the reference signal to the anode of the light emitting element through the third transistor so that a voltage corresponding to an anode potential of the light emitting element is a voltage corresponding to the reference signal;
step S914, applying a voltage greater than the second preset value to the control signal, applying a voltage less than the first preset value to the second scan signal, and applying a voltage greater than the first preset value to the third scan signal, so that the first transistor, the second transistor, the third transistor, and the seventh transistor are in an on state;
here, the first transistor and the second transistor are LTPS of PMOS, and the operation state is active low, so that the first transistor and the second transistor are in an on state in a case where a voltage smaller than a first preset value is applied to the second scan signal. The third transistor and the seventh transistor are LTPO of NMOS and active in high level, so that the third transistor is turned on when a voltage greater than a second preset value is applied to the control signal, and the seventh transistor is turned on when a voltage greater than the first preset value is applied to the third scan signal. Of course, it is also necessary to apply a voltage greater than the first preset value to the first scan signal to turn off the fourth transistor. The fifth transistor and the sixth transistor are LTPS of PMOS, the working state is effective at low level, and further the fifth transistor and the sixth transistor are in a closed state under the action of the control signal.
Step S915 of acquiring a data signal representing an image by using the first transistor, and writing the data signal into the storage capacitor;
step S916, compensating for a deviation of the threshold voltage of the second transistor by using the seventh transistor, so that a voltage corresponding to a gate potential of the second transistor is a sum of a voltage corresponding to the data signal and the threshold voltage of the second transistor;
step S917 of transmitting the reference signal to the anode of the light emitting element through the third transistor so that a voltage corresponding to an anode potential of the light emitting element is a voltage corresponding to the reference signal;
here, the execution order of the step S916 and the step S917 is not particularly required. The step S916 may be executed first and then the step S917 may be executed, or the step S917 may be executed first and then the step S916 may be executed.
Step S918, applying a voltage smaller than the second preset value to the control signal to make the second transistor, the fifth transistor and the sixth transistor in an on state;
here, the second transistor, the fifth transistor, and the sixth transistor are LTPS of PMOS, and the operation state is active low, so that the second transistor, the fifth transistor, and the sixth transistor are in an on state in a case where a voltage smaller than a second preset value is applied to the control signal. Of course, it is also necessary to apply a voltage greater than the first preset value to the first scan signal and the second scan signal, and apply a voltage less than the first preset value to the third scan signal, so that the first transistor, the third transistor, the fourth transistor, and the seventh transistor are in the off state.
Step S919 of transmitting the data signal stored in the storage capacitor to the light emitting element using the fifth transistor and the sixth transistor;
step S920, using formula I-1/2K (V)dd-Vdata)2Determining the current provided by the second transistor;
step S921, driving the light emitting element to emit light by the current, so that the light emitting element emits an optical signal corresponding to the data signal;
wherein I is a current for driving the light emitting element to emit light, and V isddFor operating voltage, said VdataFor the data signal, K is determined by the formula K ═ μ × Cox × W/L, μ is a shift rate of the second transistor, Cox is a capacitance per unit area of the storage capacitor, W is a width of the second transistor, and L is a length of the second transistor;
step S922, when the light emitting element is driven to emit light by the second transistor, setting a port corresponding to the control signal to an operating state, and setting a port corresponding to the first scanning signal, a port corresponding to the second scanning signal, and a port corresponding to the third scanning signal to a non-operating state;
step S923, the reference signal is transmitted to the anode of the light emitting element through the third transistor, so that a voltage corresponding to an anode potential of the light emitting element is a voltage corresponding to the reference signal.
The above description of the method embodiment is similar to the above description of the circuit embodiment, with similar beneficial effects as the circuit embodiment. For technical details not disclosed in the method embodiments of the present application, reference is made to the description of the circuit embodiments of the present application for understanding.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. In addition, all functional units in the embodiments of the present application may be integrated into one processing module, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit. Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments.
Features disclosed in several of the product embodiments provided in the present application may be combined in any combination to yield new product embodiments without conflict. The features disclosed in the several method or apparatus embodiments provided in the present application may be combined arbitrarily, without conflict, to arrive at new method embodiments or apparatus embodiments.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (15)

1. A pixel driving circuit, comprising: a first transistor, a storage capacitor, a data transmission path, a second transistor, a light emitting element, and a third transistor, wherein:
the first transistor, is used for making the data signal representing the picture write into the said storage capacitor;
the storage capacitor is used for storing the data signal;
the data transmission path is used for transmitting the data signal stored by the storage capacitor to the light-emitting element;
the second transistor is used for providing current to the light-emitting element so as to drive the light-emitting element to emit light;
the light-emitting element is used for emitting an optical signal corresponding to the data signal under the driving of the current;
the third transistor is configured to initialize a potential of an anode of the light-emitting element when the second transistor drives the light-emitting element to emit light.
2. The circuit of claim 1,
a source electrode of the first transistor is connected with a data signal, a grid electrode of the first transistor is connected with a second scanning signal, and a drain electrode of the first transistor is connected with a source electrode of the second transistor;
the grid electrode of the second transistor is connected with the lower electrode of the storage capacitor; the upper electrode of the storage capacitor is connected with a working voltage;
a source electrode of the third transistor is connected with a reference signal, a grid electrode of the third transistor is connected with a control signal, and a drain electrode of the third transistor is connected with an anode electrode of the light-emitting element; the cathode of the light-emitting element is connected to the voltage of the ground terminal;
the second scanning signal is used for controlling the switch of the first transistor to write the data signal line by line, the reference signal is used for potential initialization, and the control signal is used for controlling the working state of the light-emitting element.
3. The circuit of claim 2, wherein the data transmission path comprises: a fifth transistor and a sixth transistor, wherein:
the fifth transistor and the sixth transistor are configured to switch the light emitting element between different operating states, where the different operating states include an on state and an off state, and transmit a data signal in the storage capacitor to the light emitting element when the light emitting element is in the on state;
the drain electrode of the fifth transistor is connected with the source electrode of the second transistor, the grid electrode of the fifth transistor is connected with a control signal, and the source electrode of the fifth transistor is connected with a working voltage;
and the source of the sixth transistor is connected with the drain of the second transistor, the gate of the sixth transistor is connected with the control signal, and the drain of the sixth transistor is connected with the anode of the light-emitting element.
4. The circuit of claim 3, further comprising: a fourth transistor, wherein:
the fourth transistor is used for initializing the potentials of a drain electrode and a grid electrode of the second transistor;
a grid electrode of the fourth transistor is connected with a first scanning signal, a source electrode of the fourth transistor is connected with the reference signal, and a drain electrode of the fourth transistor is connected with a drain electrode of the second transistor;
the first scanning signal is used for controlling the switch of the fourth transistor so as to write the reference signal row by row.
5. The circuit of claim 4, further comprising: a seventh transistor, wherein:
the seventh transistor is configured to compensate for a deviation of a threshold voltage of the second transistor;
the drain of the seventh transistor is connected with the gate of the second transistor, the gate of the seventh transistor is connected with a third scanning signal, and the source of the seventh transistor is connected with the drain of the second transistor;
wherein the third scan signal is used to control switching of the seventh transistor.
6. The circuit according to claim 5, wherein the first transistor, the second transistor, the fourth transistor, the fifth transistor, and the sixth transistor in the circuit are low temperature polysilicon thin film transistors; the third transistor and the seventh transistor are low-temperature polysilicon and oxide thin film transistors.
7. A display device characterized in that the display device comprises the pixel drive circuit according to any one of claims 1 to 6.
8. A pixel driving method, applied to a pixel driving circuit, the method comprising:
writing the acquired data signal representing the image to a storage capacitor of the circuit using a first transistor in the circuit;
transmitting the data signal stored by the storage capacitor to a light-emitting element in the circuit by using a data transmission path in the circuit;
driving the light-emitting element to emit light by a current supplied through a second transistor in the circuit, so that the light-emitting element emits an optical signal corresponding to the data signal;
when the second transistor drives the light-emitting element to emit light, a potential of an anode of the light-emitting element is initialized by a third transistor in the circuit.
9. The method of claim 8, further comprising:
applying a voltage smaller than a first preset value to a first scanning signal, applying a voltage larger than a second preset value to a control signal, and applying a voltage larger than the first preset value to a third scanning signal, so that the third transistor, the fourth transistor and the seventh transistor are in an open state;
writing a reference signal into a lower electrode of the storage capacitor and a drain of the second transistor by using the fourth transistor and the seventh transistor, so that a voltage corresponding to a gate potential of the second transistor is a voltage corresponding to the reference signal, and a voltage corresponding to a drain potential of the second transistor is a voltage corresponding to the reference signal;
the reference signal is transmitted to the anode of the light-emitting element through the third transistor, so that a voltage corresponding to an anode potential of the light-emitting element is a voltage corresponding to the reference signal.
10. The method of claim 9, wherein writing the acquired data signals representing the image to a storage capacitor of the circuit using a first transistor in the circuit comprises:
applying a voltage greater than the second preset value to the control signal, applying a voltage less than the first preset value to a second scan signal, and applying a voltage greater than the first preset value to a third scan signal, so that the first transistor, the second transistor, the third transistor, and the seventh transistor are in an on state;
a data signal representing an image is acquired by the first transistor and written into the storage capacitor.
11. The method of claim 10, wherein after acquiring a data signal representing an image with the first transistor and writing the data signal to the storage capacitor, the method further comprises:
and compensating for a deviation of the threshold voltage of the second transistor by using the seventh transistor so that a voltage corresponding to a gate potential of the second transistor is a sum of a voltage corresponding to the data signal and the threshold voltage of the second transistor.
12. The method of claim 10 or 11, wherein after acquiring a data signal representing an image with the first transistor and writing the data signal to the storage capacitor, the method further comprises:
the reference signal is transmitted to the anode of the light-emitting element through the third transistor, so that a voltage corresponding to an anode potential of the light-emitting element is a voltage corresponding to the reference signal.
13. The method of claim 12, wherein the data transmission path includes a fifth transistor and a sixth transistor; correspondingly, the transmitting the data signal stored in the storage capacitor to the light-emitting element in the circuit by using the data transmission path in the circuit includes:
applying a voltage smaller than the second preset value to the control signal to enable the second transistor, the fifth transistor and the sixth transistor to be in an open state;
and transmitting the data signal stored in the storage capacitor to the light emitting element by using the fifth transistor and the sixth transistor.
14. The method of claim 13, wherein the current provided through the second transistor in the circuit drives the light emitting element to emit light, so that the light emitting element emits a light signal corresponding to the data signal, comprising:
using formula I ═1/2K*(Vdd-Vdata)2Determining the current provided by the second transistor;
driving the light-emitting element to emit light through the current so that the light-emitting element emits a light signal corresponding to the data signal;
wherein I is a current for driving the light emitting element to emit light, and V isddFor operating voltage, said VdataFor the data signal, K is determined by a formula K ═ μ × Cox × W/L, μ is a shift rate of the second transistor, Cox is a capacitance per unit area of the storage capacitor, W is a width of the second transistor, and L is a length of the second transistor.
15. The method according to claim 14, wherein the initializing a potential of an anode of the light-emitting element with a third transistor in the circuit when the second transistor drives the light-emitting element to emit light comprises:
when the second transistor drives the light-emitting element to emit light, setting a port corresponding to the control signal to an operating state, and setting a port corresponding to the first scanning signal, a port corresponding to the second scanning signal, and a port corresponding to the third scanning signal to a non-operating state;
the reference signal is transmitted to the anode of the light-emitting element through the third transistor, so that a voltage corresponding to an anode potential of the light-emitting element is a voltage corresponding to the reference signal.
CN202011083329.0A 2020-10-12 2020-10-12 Pixel driving circuit, display device and driving method Pending CN112233616A (en)

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