CN109166528B - Pixel circuit and driving method thereof - Google Patents
Pixel circuit and driving method thereof Download PDFInfo
- Publication number
- CN109166528B CN109166528B CN201811137277.3A CN201811137277A CN109166528B CN 109166528 B CN109166528 B CN 109166528B CN 201811137277 A CN201811137277 A CN 201811137277A CN 109166528 B CN109166528 B CN 109166528B
- Authority
- CN
- China
- Prior art keywords
- transistor
- signal
- capacitor
- pole
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Electroluminescent Light Sources (AREA)
- Control Of El Displays (AREA)
Abstract
The present invention relates to a pixel circuit, comprising: a transistor T1, a transistor T2, a transistor T3, a transistor T4, a transistor T5, a transistor T6, a capacitor C1, a capacitor C2, and a light emitting diode D1. In the pixel circuit, the first scan signal controls the transistor T3 to be turned on, the second scan signal controls the transistor T2 to be turned on, the data signal writes data into the P point through the transistor T2, the transistor T1 and the transistor T3, so that the potential of the P point is Vdata + Vth, and thus threshold compensation of the control terminal of the transistor T1 is realized, so that current flows through the light emitting diode D1, and then the light emitting diode D1 emits light.
Description
Technical Field
The present invention relates to the field of display, and in particular, to a pixel circuit and a driving method thereof.
Background
Organic light emitting display panels are increasingly used in the display field because of their advantages of high contrast, low power consumption, wide viewing angle, fast response speed, etc. Generally, the organic light emitting display panel includes pixel circuits arranged in an array, the pixel circuits generally include a light emitting diode D1 and a power supply, and a current flowing through the light emitting diode D1 is related to a power supply voltage. In the manufacturing process of the display panel, the threshold voltage of each driving transistor on the display panel is different due to process reasons, so that the driving currents flowing through the driving transistors are different, and further the currents flowing through the light emitting diodes D1 are also different, and the light emitting brightness of the display panel is uneven.
Disclosure of Invention
In view of this, it is necessary to provide a pixel circuit and a driving method thereof for solving the problem of non-uniform light emission luminance due to different threshold voltages of each driving transistor on a display panel. A pixel circuit, comprising: a transistor T1, a transistor T2, a transistor T3, a transistor T4, a transistor T5, a transistor T6, a capacitor C1, a capacitor C2, and a light emitting diode D1;
a control terminal of the transistor T5 is used for inputting a first lighting control signal, a first pole of the transistor T5 is connected to a first plate of the capacitor C1 and a first power supply VDD, a second pole of the transistor T5 is connected to a second pole of the transistor T2 and a first pole of the transistor T1, a control terminal of the transistor T2 is used for inputting a second scan signal, and a first pole of the transistor T2 is used for inputting a data signal;
a control terminal of the transistor T1 is connected to the second plate of the capacitor C1, the first plate of the capacitor C2 and the second pole of the transistor T3, and the second pole of the transistor T1 is connected to the first pole of the transistor T3 and the first pole of the transistor T6;
the control terminal of the transistor T6 is used for inputting a second light emitting control signal, the second pole of the transistor T6 is connected to the first pole of the transistor T4 and the anode of the light emitting diode D1, and the cathode of the light emitting diode D1 is connected to a second power source VSS;
a control terminal of the transistor T4 is connected to a control terminal of the transistor T3 for inputting a first scan signal, and a second pole of the transistor T4 is connected to the second plate of the capacitor C2 for inputting an initialization signal. In one embodiment, the pixel circuit further includes a transistor T7, a control terminal of the transistor T7 is connected to a control terminal of the transistor T6 for inputting a second light emission control signal, a first electrode of the transistor T7 is connected to the second plate of the capacitor C1, the first plate of the capacitor C2, a control terminal of the transistor T1, and a second electrode of the transistor T3, respectively, and the second electrode of the transistor T7 is floating.
In one embodiment, the transistor T1, the transistor T2, the transistor T3, the transistor T4, the transistor T5, the transistor T6, and the transistor T7 are any one of a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, and an amorphous silicon thin film transistor.
In one embodiment, the voltage value of the initialization signal is less than or equal to the voltage value of the second power supply VSS.
In the pixel circuit, the first scan signal controls the transistor T3 and the transistor T4 to be turned on, the second light emitting signal controls the transistor T6 to be turned on, so that the initialization signal VINT initializes the second plate of the capacitor C1, the first plate of the capacitor C2 and the control terminal of the transistor T1 through the transistor T3, the transistor T4 and the transistor T6, and the transistor T1 is turned on during initialization. The first scanning signal controls the transistor T3 to be turned on, the second scanning signal controls the transistor T2 to be turned on, the data signal writes data into the point P through the transistor T2, the transistor T1 and the transistor T3, so that the potential of the point P is Vdata + Vth, and thus threshold compensation of the control terminal of the transistor T1 is achieved, so that current flows through the light emitting diode D1, and then the light emitting diode D1 emits light.
A driving method of a pixel circuit is based on the pixel circuit and comprises the following steps:
in the initialization stage, the first scanning signal and the second light-emitting control signal are low-level signals, the second scanning signal and the first light-emitting control signal are high-level signals, and the initialization signal initializes the pixel circuit;
a data writing stage in which the first scan signal and the second scan signal are low-level signals and the first light emission control signal and the second light emission control signal are high-level signals, so that the data signal is written into the pixel circuit;
in a light emitting period, the first and second light emitting control signals are low level signals, and the first and second scan signals are high level signals, so that the light emitting diode D1 emits light.
In one embodiment, the method further includes an error compensation phase, which is arranged after the data writing phase, and the first scan signal changes from low level to high level at a starting time of the error compensation phase, and the second emission control signal changes from high level to low level at an ending time of the error compensation phase, so as to perform error compensation on the control terminal of the transistor T1.
In one embodiment, in the initialization phase, the first scan signal controls the transistor T4 and the transistor T3 to be turned on, the second emission control signal controls the transistor T6 to be turned on, and the initialization signal initializes the second plate of the capacitor C1 and the first plate of the first electrode C2 through the transistor T4, the transistor T6 and the transistor T3.
In one embodiment, in the data writing phase, the first scan signal controls the transistor T3 to be turned on, the second scan signal controls the transistor T2 to be turned on, and the data signal charges the capacitor C1 and the capacitor C2 through the transistor T2, the transistor T1 and the transistor T3, so that a potential of a common connection point of the second plate of the capacitor C1, the first plate of the capacitor C2 and the control terminal of the transistor T1 is Vdata + Vth.
In one embodiment, at the beginning of the error compensation phase, the first scan signal jumps from low level to high level, and a forward compensation error is introduced into the control terminal of the transistor T1; at the end of the error compensation phase, the second light emitting control signal jumps from high level to low level to introduce a negative compensation error at the control terminal of the transistor T1, and suppress the positive compensation error.
In one embodiment, in the light emitting phase, the first light emitting control signal controls the transistor T5 to be turned on, and the second light emitting control signal controls the transistor T6 to be turned on, so that a current flows through the light emitting diode D1.
In the driving method of the pixel circuit, in the data writing stage, the first scanning signal controls the transistor T3 to be turned on, the second scanning signal controls the transistor T2 to be turned on, and the data signal writes data into the point P through the transistor T2, the transistor T1 and the transistor T3, so that the potential of the point P is Vdata + Vth, and thus threshold compensation of the control end of the transistor T1 is realized.
Drawings
FIG. 1 is a schematic diagram of a pixel circuit according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a pixel circuit according to yet another embodiment of the present application;
FIG. 3 is a timing diagram of a pixel circuit control method according to an embodiment of the present application;
FIG. 4 is a graph showing simulation results of P-point potentials at various stages of the pixel circuit and the driving method thereof shown in FIG. 2 and FIG. 3;
fig. 5 is a partially enlarged view of a simulation result chart shown in fig. 4.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
Unless defined otherwise, all 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 in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1, an embodiment of the present application provides a pixel circuit including a transistor T1, a transistor T2, a transistor T3, a transistor T4, a transistor T5, a transistor T6, a capacitor C1, a capacitor C2, and a light emitting diode D1.
The pixel circuit further includes a first scan signal terminal and a second scan signal terminal. The first SCAN signal terminal is connected to the control terminals of the transistor T3 and the transistor T4, and is used for inputting a first SCAN signal SCAN1 to the control terminal of the transistor T3 and the control terminal of the transistor T4 to control the conduction of the transistor T3 and the transistor T4. The second SCAN signal terminal is connected to the control terminal of the transistor T2, and is used for inputting the second SCAN signal SCAN2 to the control terminal of the transistor T2 to control the conduction of the transistor T2. The first light-emitting control signal input terminal is connected to the control terminal of the transistor T5, and is used for controlling the transistor T5 to be turned on and off. The second light emitting control signal input terminal is connected to the control terminal of the transistor T6 for controlling the transistor T6 to be turned on or off. The data signal input terminal is connected to a first pole of the transistor T2 for threshold compensation of the transistor T1 through the transistor T2. The initialization signal input terminal is connected to the second pole of the transistor T4 and the second plate of the capacitor C2 for initializing the capacitor C1 and the capacitor C2 and the anode of the light emitting diode D1.
Specifically, the control terminal of the transistor T5 is used for inputting the first light emitting control signal, the first pole of the transistor T5 is connected to the first plate of the capacitor C1 and the first power source VDD, and the second pole of the transistor T5 is connected to the second pole of the transistor T2 and the second pole of the transistor T1. The control terminal of the transistor T2 is used for inputting the second scan signal, and the first pole of the transistor T2 is used for inputting the data signal. The control terminal of transistor T1 is connected to the second plate of capacitor C1, the first plate of capacitor C2 and the second pole of transistor T3, point P being its common connection point, and the second pole of transistor T1 is connected to the first pole of transistor T3 and the first pole of transistor T6. The control terminal of the transistor T6 is used for inputting a second light emitting control signal, and the second pole of the transistor T6 is connected to the first pole of the transistor T4 and the anode of the light emitting diode D1. The cathode of the light emitting diode D1 is connected to a second power source VSS. A control terminal of the transistor T4 is connected to the control terminal of the transistor T3 for inputting the first scan signal, and a second pole of the transistor T4 is connected to the second plate of the capacitor C2 for inputting the initialization signal VINT.
In the above embodiment, the first scan signal controls the transistor T3 and the transistor T4 to be turned on, the second light emitting signal controls the transistor T6 to be turned on, so that the initialization signal VINT initializes the second plate of the capacitor C1, the first plate of the capacitor C2, and the control terminal of the transistor T1 through the transistor T3, the transistor T4, and the transistor T6, and the transistor T1 is turned on at the time of initialization. The first scan signal controls the transistor T3 to be turned on, the second scan signal controls the transistor T2 to be turned on, and the data signal writes data into the point P through the transistor T2, the transistor T1, and the transistor T3, so that the potential of the point P is Vdata + Vth, and thus threshold compensation of the control terminal of the transistor T1 is achieved. The first light-emitting control signal controls the transistor T5 to be conducted, the second light-emitting control signal controls the transistor T6 to be conducted, so that current flows through the light-emitting diode D1, and then the light-emitting diode D1 emits light, and as threshold compensation is carried out on the control end of the transistor T1 in a data writing stage, the current flowing through the transistor T1 can be unrelated to the threshold voltage of the transistor T1, so that the problem of uneven light emission caused by different threshold voltages of different driving transistors is solved, and the light-emitting uniformity of the screen body is improved.
Further, referring to fig. 2, the pixel circuit may further include a transistor T7. The control terminal of the transistor T7 is connected to the control terminal of the transistor T6 for inputting the second light emission control signal, the first pole of the transistor T7 is connected to the point P, and the second pole of the transistor T7 is floating.
After the data writing phase, the first scan signal jumps to turn off the transistor T3, and the P-point potential rises due to the coupling effect of the transistor T3, thereby causing a forward compensation error at the P-point. At the beginning of the light-emitting period, the second light-emitting control signal jumps from high level to low level, the transistor T7 turns from off to on, the potential at the P point drops due to the coupling effect of the transistor T7, and at the same time, the potential at the P point can be further reduced due to the absorption of charges required for the conduction of the channel of the transistor T7, so that a negative compensation error is introduced at the P point. The negative compensation error can partially offset the positive compensation error, thereby reducing the total compensation error at the point P. Therefore, the compensation error generated during threshold compensation can be reduced by introducing the transistor T7, so that the accuracy of threshold compensation is higher, and the light emitting uniformity of the screen body is improved.
In the above embodiments, the transistor T2, the transistor T3, the transistor T4, the transistor T5, the transistor T6, and the transistor T7 are all switching transistors, and the transistor T1 is a driving transistor. The capacitor C1 and the capacitor C2 are energy storage capacitors, and the Light Emitting Diode D1 is an OLED (Organic Light-Emitting Diode). The transistors in the above embodiments are all P-type transistors, and it is understood that the control terminal is a gate of the transistor, the first electrode is a source of the transistor, the second electrode is a drain of the transistor, and a low level is applied to the control terminal of the transistor to turn on the transistor. Of course, in other embodiments, the transistor may be an N-type transistor, and when the N-type transistor is used as a transistor in the pixel circuit, a high-level signal is input to a control terminal of the transistor to turn on the transistor.
In the above embodiment, the first power supply VDD may be a positive voltage, and the second power supply VSS may be a negative voltage. The driving transistor T1 may generate a current by the first power source VDD, the current flows through the light emitting diode D1 to make the light emitting diode D1 emit light, and the current flows from the light emitting diode D1 to the second power source VSS when the light emitting diode D1 emits light.
In one embodiment, the width-to-length ratios of the transistor T2, the transistor T3, the transistor T4, the transistor T5, the transistor T6 and the transistor T7 are equal, so that the brightness unevenness and the gray scale inaccuracy of the organic light emitting diode OLED due to the size difference of the switching transistors are avoided.
In one embodiment, the transistor T1, the transistor T2, the transistor T3, the transistor T4, the transistor T5, the transistor T6, the transistor T7, and the transistor T8 may be any one of a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, and an amorphous silicon thin film transistor.
One embodiment of the present application provides a display panel, which includes the aforementioned pixel circuits arranged in an array. The display panel further includes a data driver, a scan driver, and a light emission controller. One end of each of the first SCAN signal line and the second SCAN signal line is connected to the first SCAN signal end of each row of the pixel circuits, and the other end is connected to the SCAN driver, and the SCAN driver provides the first SCAN signal SCAN1 and the second SCAN signal SCAN2, and transmits the signals to the pixel circuits through the first SCAN signal line and the second SCAN signal line. One end of the data signal line is connected with the data signal input end of each column of pixel circuits, the other end of the data signal line is connected with the data driver, and the data driver provides data signals and transmits the data signals to the pixel circuits through the data signal line. One end of each of the first light-emitting control signal line and the second light-emitting control signal line is correspondingly connected with each row of pixel circuits, the other end of each of the first light-emitting control signal line and the second light-emitting control signal line is connected with a light-emitting controller, and the light-emitting controller provides light-emitting control signals and transmits the light-emitting control signals to the pixel circuits through the first light-emitting control signal line and the second light-emitting control signal line.
An embodiment of the present application provides a display device including the above display panel.
Referring to fig. 1 and fig. 3, fig. 1 is a timing signal diagram of a pixel circuit according to an embodiment of the present disclosure, and fig. 3 is a timing signal diagram for driving the pixel circuit shown in fig. 1. An embodiment of the present application provides a driving method of the above pixel circuit, which includes the following three stages:
in the initialization stage t1, the first SCAN signal SCAN1 and the second emission control signal EM2 are low level signals, and the second SCAN signal SCAN2 and the first emission control signal EM1 are high level signals, so that the pixel circuit is initialized by the initialization signal VINT.
In the data writing phase t2, the first SCAN signal SCAN1 and the second SCAN signal SCAN2 are low level signals, and the first emission control signal EM1 and the second emission control signal EM2 are high level signals, so that the data signals are written into the pixel circuits.
In the light emitting period t3, the first and second light emission control signals EM1 and EM2 are low level signals, and the first and second SCAN signals SCAN1 and SCAN signals SCAN2 are high level signals, so that the light emitting diode D1 emits light.
Specifically, in the initialization stage T1, the first SCAN signal SCAN1 controls the transistor T4 and the transistor T3 to be turned on, the second emission control signal EM2 controls the transistor T6 to be turned on, the initialization signal VINT initializes the anode of the light emitting diode D1 through the transistor T4, the initialization signal VINT initializes the control terminal of the transistor T1 through the transistor T4, the transistor T6 and the transistor T3, and the initialization signal VINT controls the transistor T1 to be turned on.
In the data writing phase T2, the first SCAN signal SCAN1 controls the transistor T3 to be turned on, and the second SCAN signal SCAN2 controls the transistor T2 to be turned on. In the initialization period T1, the transistor T1 is turned on, so that the data signal can charge the second plate of the capacitor C1 and the first plate of the capacitor C2 through the transistor T2, the transistor T1 and the transistor T3 until the transistor T1 is turned off, at which time the potential at the point P is Vdata + Vth.
In the light-emitting period T3, the first light-emitting control signal EM1 controls the transistor T5 to be turned on, and the second light-emitting control signal EM2 controls the transistor T6 to be turned on, so that a current flows through the light-emitting diode D1 through the transistor T5, the transistor T1 and the transistor T6.
Further, referring to fig. 2 and fig. 3, the pixel circuit shown in fig. 2 is additionally provided with a transistor T7 on the basis of fig. 1, for performing error compensation on the control terminal of the transistor T1 during the error compensation phase. The operation of the pixel circuit shown in fig. 2 in the initialization stage t1, the data writing stage t2 and the light emitting stage t3 is the same as that of the pixel circuit shown in fig. 1, and therefore, the description thereof is omitted, and the operation of the pixel circuit shown in fig. 2 in the error compensation stage is mainly described. Specifically, at the beginning of the error compensation phase Δ T, i.e. the transition time from the data writing phase T2 to the error compensation phase Δ T, the first SCAN signal SCAN1 transitions from a low level to a high level, the first SCAN signal SCAN1 controls the transistor T3 to change from an on state to an off state, and the potential at the P point rises due to the coupling effect of the transistor T3, so that a forward compensation error is introduced at the P point. At the end of the error compensation phase Δ T, i.e. the transition time from the error compensation phase Δ T to the light emitting phase T3, the second light emission control signal EM2 jumps from high level to low level, the second light emission control signal EM2 controls the transistor T7 to turn from off state to on state, the potential of the P point drops due to the coupling effect of the transistor T7, meanwhile, the transistor T7 needs to absorb charges to establish a conductive channel to turn on the first pole and the second pole, and the first pole of the transistor T7 is connected to the point P of the common connection point, so that the charges come from the point P, and further drop the potential of the point P, thereby introducing a negative compensation error at the point P. The negative compensation error can offset part of the positive compensation error, so that the total compensation error of the point P is reduced, namely the compensation error of the control end of the transistor T1 is reduced, the threshold compensation effect is better, and the uniformity of the screen brightness is improved.
The following describes the operation principle of the pixel circuit based on fig. 1 and 2:
in the initialization stage t1, both the first SCAN signal SCAN1 and the second emission control signal EM2 are low level signals. Since the control terminals of the transistor T3 and the transistor T4 are connected to the first SCAN signal terminal, and the transistor T6 and the transistor T7 are connected to the second emission control signal input terminal, the first SCAN signal SCAN1 controls the transistor T3 and the transistor T4 to be turned on, and the second emission control signal EM2 controls the transistor T6 and the transistor T7 to be turned on. The initialization signal VINT initializes the anode of the led D1 through the transistor T4, and initializes the second plate of the capacitor C1 and the first plate of the capacitor C2 through the transistor T4, the transistor T6 and the transistor 3, so as to ensure that the data signal can be effectively written into the capacitors C1 and C2 in the data writing stage T2. It is understood that the voltage value of the initialization signal VINT is less than or equal to the voltage value of the second power source VSS to ensure that the light emitting diode D1 does not emit light during the initialization period.
In the data writing phase t2, the first and second SCAN signals SCAN1 and SCAN2 are low level signals, and the first and second emission control signals EM1 and EM2 are high level signals. The first SCAN signal SCAN1 controls the transistor T3 to be turned on, the second SCAN signal SCAN2 controls the transistor T2 to be turned on, and the transistor T1 is turned on in the initialization period T1, so that the data signal can charge the second plate of the capacitor C1 and the first plate of the capacitor C2 through the transistor T2, the transistor T1 and the transistor T3 until T1 is turned off, and the potential at the point P is Vdata + Vth, thereby writing the data signal and the threshold voltage of the driving transistor into the control terminal of the transistor T1.
In the error compensation phase Δ T, at the transition time from the data writing phase T2 to the error compensation phase Δ T, the first SCAN signal SCAN1 jumps from a low level signal to a high level signal, the first SCAN signal SCAN1 controls the transistor T3 to turn from an on state to an off state, and the second pole of the transistor T3 is connected to the point P of the common connection point, so that the potential of the point P is raised due to the coupling effect of the transistor T3, and a forward compensation error Δ V1 is introduced into the point P. At the transition time from the error compensation phase Δ T to the light emitting phase T3, the second light emitting control signal EM2 changes from a high level signal to a low level signal, so that the second light emitting control signal EM2 controls the transistor T7 to change from a closed state to a conductive state, the first pole of the transistor T7 is connected to the point P of the common connection point, on one hand, the potential of the point P is decreased due to the coupling effect of the transistor T7, and a negative compensation error is introduced, on the other hand, the second pole of the transistor T7 is floating, and when the transistor T7 is turned on, a charge is required for forming a conduction channel, so that the second pole of the transistor T7 needs to absorb the charge from the point P, further causing the potential of the point P to be decreased, and the negative compensation error Δ V36. The total compensation error at point P is therefore Δ V ═ Δ V1- Δ V2, where Δ V1 changes in the opposite direction to Δ V2, so that the compensation error is suppressed. When the error compensation stage Δ t is finished, the P point potential is Vdata + Vth + Δ V.
In the light-emitting period t3, the first and second light-emitting control signals EM1 and EM2 are both low-level signals, and the first and second SCAN signals SCAN1 and SCAN2 are both high-level signals. Since the control terminal of the transistor T5 is connected to the first lighting control signal input terminal, the transistor T5 is controlled to be turned on when the first lighting control signal EM1 is low. Since the control terminal of the transistor T6 is connected to the second emission control signal input terminal, the transistor T6 is controlled to be turned on when the second emission control signal EM2 is at a low level. Since the transistor T5 is turned on, the first power VDD is written into the first electrode of the transistor T1, so that the first voltage of the transistor T1 is VDD, the transistor T1 is turned on, and therefore, a loop from the first power VDD, the transistor T5, the transistor T1, the transistor T6 to the second power VSS is turned on, the transistor T1 generates a driving current under the action of the first power VDD, and the driving current flowing through the transistor T1 is a light emitting current flowing through the light emitting diode D1. The driving current flowing through the transistor T1 is:
I＝K*(Vgs-Vth)2＝K*[(Vdata+Vth+ΔV-VDD)-Vth]2＝K*(Vdata-VDD+ΔV)2。
wherein K is 1/2 mu Cox W/L. μ is the electron mobility of the transistor T1, Cox is the gate oxide capacitance per unit area of the transistor T1, W is the channel width of the transistor T1, and L is the channel length of the transistor T1. As can be seen from the above formula, the current flowing through the led D1 is independent of the threshold voltage of the transistor T1, so that the non-uniform light emission phenomenon of the display panel due to the difference in threshold voltage can be compensated. Meanwhile, in the error compensation stage delta t, the voltage fluctuation of the common connection point P is compensated by offsetting the positive part and the negative part, so that the total compensation error is smaller, the compensation effect is better, and the uniformity of the screen brightness is higher.
Referring to fig. 4 and 5, fig. 4 is a graph showing simulation results of P-point potentials at various stages obtained by simulation according to the circuit diagram and the control method provided in the present application. FIG. 5 is a partial enlarged view of the P-point potential at the error compensation stage. As can be seen from fig. 4 and 5, a positive compensation error Δ V1 is introduced at the point P due to the high jump of the first SCAN signal SCAN1, and then a negative compensation error Δ V2 is introduced at the point P due to the low jump of the second emission control signal EM2, and the negative compensation error Δ V2 partially cancels the positive compensation error Δ V1, so that the actual compensation error at the point P is reduced, that is, the compensation error at the control terminal of the transistor T1 is reduced, the threshold compensation effect is better, and the uniformity of the screen brightness is improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A pixel circuit, comprising: a transistor T1, a transistor T2, a transistor T3, a transistor T4, a transistor T5, a transistor T6, a capacitor C1, a capacitor C2, and a light emitting diode D1;
a control terminal of the transistor T5 is used for inputting a first lighting control signal, a first pole of the transistor T5 is connected to a first plate of the capacitor C1 and a first power supply VDD, a second pole of the transistor T5 is connected to a second pole of the transistor T2 and a first pole of the transistor T1, a control terminal of the transistor T2 is used for inputting a second scan signal, and a first pole of the transistor T2 is used for inputting a data signal;
a control terminal of the transistor T1 is connected to the second plate of the capacitor C1, the first plate of the capacitor C2 and the second pole of the transistor T3, and the second pole of the transistor T1 is connected to the first pole of the transistor T3 and the first pole of the transistor T6;
the control terminal of the transistor T6 is used for inputting a second light emitting control signal, the second pole of the transistor T6 is connected to the first pole of the transistor T4 and the anode of the light emitting diode D1, and the cathode of the light emitting diode D1 is connected to a second power source VSS;
the control terminal of the transistor T4 is connected to the control terminal of the transistor T3 for inputting a first scan signal, and the second pole of the transistor T4 is connected to the second plate of the capacitor C2 for inputting an initialization signal;
the pixel circuit further comprises a transistor T7, a control terminal of the transistor T7 is connected to a control terminal of the transistor T6 and is configured to input a second light-emitting control signal, a first electrode of the transistor T7 is respectively connected to a second electrode plate of the capacitor C1, a first electrode plate of the capacitor C2, a control terminal of the transistor T1 and a second electrode of the transistor T3, and the second electrode of the transistor T7 is floating.
2. The pixel circuit according to claim 1, wherein the transistor T1, the transistor T2, the transistor T3, the transistor T4, the transistor T5, the transistor T6, and the transistor T7 are any one of a low-temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, and an amorphous silicon thin film transistor.
3. The pixel circuit according to claim 2, wherein a voltage value of the initialization signal is equal to or less than a voltage value of the second power source VSS.
4. A driving method of a pixel circuit, the pixel circuit according to any one of claims 1 to 3, comprising:
in the initialization stage, the first scanning signal and the second light-emitting control signal are low-level signals, the second scanning signal and the first light-emitting control signal are high-level signals, and the initialization signal initializes the pixel circuit;
a data writing stage in which the first scan signal and the second scan signal are low-level signals and the first light emission control signal and the second light emission control signal are high-level signals, so that the data signal is written into the pixel circuit;
an error compensation phase in which the first scan signal is changed from a low level to a high level at a start time of the error compensation phase, and the second emission control signal is changed from a high level to a low level at an end time of the error compensation phase to perform error compensation on the control terminal of the transistor T1;
in a light emitting period, the first and second light emitting control signals are low level signals, and the first and second scan signals are high level signals, so that the light emitting diode D1 emits light.
5. The method for driving a pixel circuit according to claim 4, wherein in the initialization phase, the first scan signal controls the transistor T4 and the transistor T3 to be turned on, the second emission control signal controls the transistor T6 to be turned on, and the initialization signal initializes the second plate of the capacitor C1 and the first plate of the second capacitor C2 through the transistor T4, the transistor T6 and the transistor T3.
6. The method of driving the pixel circuit according to claim 5, wherein in the data writing phase, the first scan signal controls the transistor T3 to be turned on, the second scan signal controls the transistor T2 to be turned on, and the data signal charges the capacitor C1 and the capacitor C2 through the transistor T2, the transistor T1 and the transistor T3, so that a potential of a common connection point of the second plate of the capacitor C1, the first plate of the capacitor C2 and the control terminal of the transistor T1 is Vdata + Vth.
7. The driving method of the pixel circuit according to claim 5, wherein at a start time of the error compensation phase, the first scan signal jumps from a low level to a high level, introducing a forward compensation error at the control terminal of the transistor T1; at the end of the error compensation phase, the second light emitting control signal jumps from high level to low level to introduce a negative compensation error at the control terminal of the transistor T1, and suppress the positive compensation error.
8. The method according to claim 7, wherein in the light-emitting period, the first light-emitting control signal controls the transistor T5 to be turned on, and the second light-emitting control signal controls the transistor T6 to be turned on, so that a current flows through the light-emitting diode D1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811137277.3A CN109166528B (en) | 2018-09-28 | 2018-09-28 | Pixel circuit and driving method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811137277.3A CN109166528B (en) | 2018-09-28 | 2018-09-28 | Pixel circuit and driving method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109166528A CN109166528A (en) | 2019-01-08 |
| CN109166528B true CN109166528B (en) | 2020-05-19 |
Family
ID=64892846
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811137277.3A Active CN109166528B (en) | 2018-09-28 | 2018-09-28 | Pixel circuit and driving method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109166528B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4002337A4 (en) * | 2020-05-22 | 2022-10-19 | BOE Technology Group Co., Ltd. | Display substrate, display panel, and display device |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109584788A (en) | 2019-01-22 | 2019-04-05 | 京东方科技集团股份有限公司 | Pixel-driving circuit, pixel unit and driving method, array substrate, display device |
| CN110534062A (en) * | 2019-08-30 | 2019-12-03 | 昆山国显光电有限公司 | OLED pixel driving circuit, control method and display device |
| CN110459177A (en) * | 2019-08-30 | 2019-11-15 | 昆山国显光电有限公司 | OLED pixel circuit and display device |
| WO2021047562A1 (en) | 2019-09-12 | 2021-03-18 | 京东方科技集团股份有限公司 | Pixel driving circuit, pixel unit, driving method, array substrate, and display device |
| CN111681611B (en) * | 2020-06-11 | 2021-06-25 | 昆山国显光电有限公司 | Pixel circuit and display device |
| WO2022061852A1 (en) * | 2020-09-28 | 2022-03-31 | 京东方科技集团股份有限公司 | Pixel driving circuit and display panel |
| CN112599091A (en) * | 2020-12-29 | 2021-04-02 | 福建华佳彩有限公司 | Compensation circuit and driving method |
| CN113421525B (en) * | 2021-06-21 | 2022-12-09 | 福州京东方光电科技有限公司 | Pixel driving circuit, display panel, display device and driving control method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105679237A (en) * | 2014-12-02 | 2016-06-15 | 三星显示有限公司 | Organic light emitting display and driving method of the same |
| CN107945743A (en) * | 2018-01-04 | 2018-04-20 | 京东方科技集团股份有限公司 | A kind of image element circuit, its driving method and display device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI564855B (en) * | 2011-11-18 | 2017-01-01 | 國立成功大學 | Source follower circuit for data driver in display and method thereof |
| KR102265368B1 (en) * | 2015-01-13 | 2021-06-15 | 삼성디스플레이 주식회사 | Pixel, display device comprising the same and driving method thereof |
| KR102505328B1 (en) * | 2016-04-28 | 2023-03-03 | 삼성디스플레이 주식회사 | Organic light emitting diode display device |
-
2018
- 2018-09-28 CN CN201811137277.3A patent/CN109166528B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105679237A (en) * | 2014-12-02 | 2016-06-15 | 三星显示有限公司 | Organic light emitting display and driving method of the same |
| CN107945743A (en) * | 2018-01-04 | 2018-04-20 | 京东方科技集团股份有限公司 | A kind of image element circuit, its driving method and display device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4002337A4 (en) * | 2020-05-22 | 2022-10-19 | BOE Technology Group Co., Ltd. | Display substrate, display panel, and display device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109166528A (en) | 2019-01-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109166528B (en) | Pixel circuit and driving method thereof | |
| US10242625B2 (en) | Pixel driving circuit, pixel driving method and display apparatus | |
| WO2020001635A1 (en) | Drive circuit and driving method therefor, and display apparatus | |
| CN109064975B (en) | Pixel circuit, driving method thereof, display panel and display device | |
| CN108648696B (en) | Pixel circuit, array substrate, display device and pixel driving method | |
| WO2017041453A1 (en) | Pixel circuit, driving method therefor and relevant apparatus | |
| WO2018188390A1 (en) | Pixel circuit and driving method therefor, and display device | |
| CN101211535B (en) | Pixel circuit, display, and method for driving pixel circuit | |
| WO2016173124A1 (en) | Pixel circuit, driving method and related device thereof | |
| CN113539184B (en) | Pixel circuit, driving method thereof and display panel | |
| WO2017117938A1 (en) | Pixel driving circuit, pixel driving method, and display device | |
| CN106097976B (en) | Pixel-driving circuit and display device | |
| US20190228708A1 (en) | Pixel circuit, pixel driving method and display device | |
| CN104809989A (en) | Pixel circuit, drive method thereof and related device | |
| US20160133187A1 (en) | Pixel circuit and driving method thereof, display apparatus | |
| US10748489B2 (en) | Pixel driving circuit and driving method thereof, and display apparatus | |
| CN108777131B (en) | AMOLED pixel driving circuit and driving method | |
| CN109166522B (en) | Pixel circuit, driving method thereof and display device | |
| CN110164375B (en) | Pixel compensation circuit, driving method, electroluminescent display panel and display device | |
| CN114822396B (en) | Pixel driving circuit and display panel | |
| CN110610683B (en) | Pixel driving circuit, driving method thereof, display panel and display device | |
| CN106782322A (en) | AMOLED pixel-driving circuits and AMOLED image element driving methods | |
| CN112750392B (en) | Pixel driving circuit, driving method thereof, display panel and display device | |
| WO2018054141A1 (en) | Pixel circuit, display panel, display device, and driving method | |
| WO2021000816A1 (en) | Pixel circuit and driving method therefor, and display device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |