CN108538251A - Pixel circuit and its driving method, display device - Google Patents
Pixel circuit and its driving method, display device Download PDFInfo
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- CN108538251A CN108538251A CN201710125364.6A CN201710125364A CN108538251A CN 108538251 A CN108538251 A CN 108538251A CN 201710125364 A CN201710125364 A CN 201710125364A CN 108538251 A CN108538251 A CN 108538251A
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
- G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3266—Details of drivers for scan electrodes
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Electroluminescent Light Sources (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
The present invention provides a kind of pixel circuit and its driving method, display device, which includes first film transistor, the second thin film transistor (TFT), third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT), the 8th thin film transistor (TFT), the first capacitance and luminescent device.The present invention compensates the threshold voltage of first film transistor (driving thin film transistor (TFT)), so that the electric current for flowing through luminescent device is become unrelated with the threshold voltage of first film transistor, improves the display effect of picture.
Description
Technical field
The present invention relates to and display technology field, more particularly to a kind of pixel circuit and its driving method, display device.
Background technology
Organic Light Emitting Diode (Organic Light Emitting Display, OLED) display device has spontaneous
Light, driving voltage are low, luminous efficiency is high, the response time is short, clarity and contrast are high, nearly 180 ° of visual angles, use temperature ranges
Width is known as being the display for most having development potentiality by industry, it can be achieved that many advantages, such as Flexible Displays are with large area total colouring
Device.
OLED display according to type of drive can be divided into passive matrix OLED (Passive Matrix OLED,
) and active array type OLED (Active Matrix OLED, AMOLED) two major classes, i.e. direct addressin and film PMOLED
Two class of transistor (Thin Film Transistor, TFT) matrix addressing.Wherein, AMOLED has the picture in array arrangement
Element belongs to active display type, and luminous efficacy is high, is typically used as high-definition large scale display device.
AMOLED is current driving apparatus, when there is electric current to flow through Organic Light Emitting Diode, organic light-emitting diode,
And light emission luminance is determined by the electric current for flowing through Organic Light Emitting Diode itself.Most of existing integrated circuit (Integrated
Circuit, IC) voltage signal is all only transmitted, therefore the pixel-driving circuit of AMOLED needs to complete voltage signal being changed into electricity
Flow the task of signal.Traditional pixel circuit is usually 2T1C, i.e., two thin film transistor (TFT)s add the structure of a capacitance, by voltage
It is transformed to electric current.
As described in Figure 1, it is traditionally used for the 2T1C pixel-driving circuits of AMOLED, including a first film transistor T10,
One second thin film transistor (TFT) T20 and a capacitance C, the first film transistor T10 are switching thin-film transistor, described the
Two thin film transistor (TFT) T20 are driving thin film transistor (TFT), and the capacitance C is storage capacitance.Specifically, the first film transistor
The grid of T10 is electrically connected scanning signal Scan, and source electrode is electrically connected data-signal Data, drain electrode and the second thin film transistor (TFT)
The grid of T20 and one end of capacitance C are electrically connected；The source electrode of the second thin film transistor (TFT) T20 is electrically connected first voltage
VDD, drain electrode is held to be electrically connected the anode of organic Light-Emitting Diode D；The minus earth of organic light emitting diode D；One end of capacitance C
It is electrically connected the drain electrode of first film transistor T10, the other end is electrically connected the source electrode of the second thin film transistor (TFT) T20.AMOLED
When display, scanning signal Scan control first film transistors T10 is opened, and data-signal Data passes through first film transistor
T10 enters the grid and capacitance C of the second thin film transistor (TFT) T20, and then first film transistor T10 is closed, due to capacitance C
Memory action, the grid voltage of the second thin film transistor (TFT) T20 may continue to keep voltage data signal so that the second film is brilliant
Body pipe T20 is in the conduction state, drives current through the second thin film transistor (TFT) T20 and enters organic light emitting diode D, driving is organic
Light-Emitting Diode D shines.
Threshold voltage shift of the above-mentioned 2T1C pixel-driving circuits for being traditionally used for AMOLED to driving thin film transistor (TFT)
Very sensitive, with the threshold voltage shift of driving thin film transistor (TFT), the curent change for flowing through Organic Light Emitting Diode is very big, directly
Lead to Organic Light Emitting Diode it is luminous it is very unstable, brightness is very uneven, greatly influence the display effect of picture.
Invention content
The purpose of the present invention is to provide a kind of pixel circuit and its driving methods, and to solve, display brightness is non-uniform to ask
Topic.
In order to solve the above technical problems, the present invention provides a kind of pixel circuit, including：It is first film transistor, second thin
Film transistor, third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th film
Transistor, the 8th thin film transistor (TFT), the first capacitance and luminescent device；Wherein, the grid of first film transistor is electrically connected
In one end of the first capacitance, the first electrode of the first electrode of the 8th thin film transistor (TFT) and third thin film transistor (TFT), first is thin
The first electrode of film transistor be electrically connected at the second thin film transistor (TFT) second electrode and the 6th thin film transistor (TFT) second
The second electrode of electrode, first film transistor is electrically connected at the first electrode and the 8th film crystalline substance of the 7th thin film transistor (TFT)
The second electrode of body pipe；The grid of second thin film transistor (TFT) and the 8th thin film transistor (TFT) is electrically connected at one second scan control letter
Number, the first electrode of the second thin film transistor (TFT) is electrically connected at a data-signal；Third thin film transistor (TFT), the 4th thin film transistor (TFT)
Be electrically connected at one first scan control signal with the grid of the 5th thin film transistor (TFT), the second electrode of third thin film transistor (TFT) and
The first electrode of 4th thin film transistor (TFT) is electrically connected at the first electrode of the 5th thin film transistor (TFT)；The of 4th thin film transistor (TFT)
Two electrodes are electrically connected at a reference voltage signal；The second electrode of 5th thin film transistor (TFT) and the 7th thin film transistor (TFT)
Second electrode is electrically connected at the anode of luminescent device；The grid of 6th thin film transistor (TFT) and the grid electricity of the 7th thin film transistor (TFT)
Property is connected to a third scan control signal, the first electrode of the 6th thin film transistor (TFT) be electrically connected at a first voltage end and
The other end of first capacitance；The cathode of luminescent device is connected to a second voltage end.
Optionally, in the pixel circuit, the first film transistor, the second thin film transistor (TFT), third film
Transistor, the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT), the 8th film are brilliant
Body pipe is P-type transistor.
Optionally, in the pixel circuit, the first film transistor, the second thin film transistor (TFT), third film
Transistor, the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT), the 8th film are brilliant
Body pipe is low-temperature polysilicon film transistor.
Optionally, in the pixel circuit, the first electrode is source electrode, and the second electrode is drain electrode；Alternatively,
The first electrode is drain electrode, and the second electrode is source electrode.
Optionally, in the pixel circuit, first scan control signal, the second scan control signal, third
Scan control signal is provided by external sequence controller.
Optionally, in the pixel circuit, the luminescent device is OLED.
Optionally, further include the second capacitance in the pixel circuit, one end of second capacitance is electrically connected at
The other end of the grid of second thin film transistor (TFT), second capacitance is electrically connected at the grid of first film transistor.
The present invention also provides a kind of display devices, using pixel circuit as described above.
The present invention more provides a kind of driving method of pixel circuit, including：
In first time period, first film transistor, third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th film are brilliant
Body pipe is connected, and utilizes the grid voltage of reference voltage initialization signal first film transistor and the anode voltage of luminescent device；
In second time period, first film transistor, the second thin film transistor (TFT), the conducting of the 8th thin film transistor (TFT), first is thin
The grid voltage of film transistor becomes VDATA-|Vth|, wherein VDATAFor the voltage of data-signal, VthFor first film transistor
Threshold voltage；
In the third period, first film transistor, threshold is completed in the 6th thin film transistor (TFT), the conducting of the 7th thin film transistor (TFT)
Threshold voltage compensates, and driving luminescent device shines.
Optionally, in the driving method of the pixel circuit, in first time period, the first scan control signal provides
Low level, the second scan control signal, third scan control signal and data-signal provide high level；In second time period,
Two scan control signals and data-signal provide low level, and the first scan control signal and third scan control signal are provided which height
Level；In the third period, third scan control signal provides low level, the first scan control signal, the second scan control letter
Number and data-signal be provided which high level.
In pixel circuit provided by the invention and its driving method, to first film transistor (driving thin film transistor (TFT))
Threshold voltage compensate, so that the electric current for flowing through luminescent device is become unrelated with threshold voltage, to make to flow through luminescent device
The electric current of such as Organic Light Emitting Diode is stablized, and the display effect of picture is improved.
Description of the drawings
Below in conjunction with the accompanying drawings, it is described in detail by the specific implementation mode to the present invention, technical scheme of the present invention will be made
And other beneficial effects are apparent.
Fig. 1 is the circuit diagram for the 2T1C pixel-driving circuits for being traditionally used for AMOLED；
Fig. 2 is a kind of circuit diagram of pixel circuit in the embodiment of the present invention；
Fig. 3 is a kind of sequence diagram of pixel circuit in the embodiment of the present invention；
Fig. 4 is a kind of pixel circuit in the embodiment of the present invention in the schematic diagram of first time period t1；
Fig. 5 is a kind of pixel circuit in the embodiment of the present invention in the schematic diagram of second time period t2；
Fig. 6 is a kind of pixel circuit in the embodiment of the present invention in the schematic diagram of third time period t 3；
Fig. 7 is the circuit diagram of another pixel circuit in the embodiment of the present invention.
Specific implementation mode
In the background technology it has been already mentioned that traditional pixel circuit floats the threshold voltage of driving thin film transistor (TFT) (TFT)
Move it is very sensitive, and in actual production technology, it is difficult to ensure that the threshold voltage of the driving TFT of each pixel is identical, therefore, i.e.,
Keep the data voltage of each pixel the same, the electric current for flowing through OLED is also different, therefore brightness also has difference, to generate display
Non-uniform problem.Based on this, the present invention provides a kind of new pixel circuit, to driving the threshold voltage of thin film transistor (TFT) to carry out
Compensation, makes the electric current for flowing through luminescent device become unrelated with threshold voltage, can avoid due to being driven caused by threshold voltage shift
Electric current is unstable, the non-uniform problem of display brightness.Further, since the pixel circuit is using third thin film transistor (TFT), the
Four thin film transistor (TFT)s, the 5th thin film transistor (TFT) gate series pattern, advantageously reduce luminescent device initialization leakage current
With the leakage current of driving TFT.
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation describes, it is clear that described embodiment is only a part of the embodiment of the present invention, instead of all the embodiments.Based on this
Embodiment in invention, every other reality obtained by those of ordinary skill in the art without making creative efforts
Example is applied, shall fall within the protection scope of the present invention.It should be noted that attached drawing is all made of very simplified form and uses non-accurate
Ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
Referring to Fig. 2, the present embodiment provides a kind of pixel circuits, including：First film transistor M1, the second film crystal
Pipe M2, third thin film transistor (TFT) M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5, the 6th thin film transistor (TFT) M6, the 7th
Thin film transistor (TFT) M7, the 8th thin film transistor (TFT) M8, the first capacitance C1 and luminescent device L.
Wherein, the grid of first film transistor M1 is electrically connected at one end of the first capacitance C1, the 8th thin film transistor (TFT)
The first electrode of M8 and the first electrode of third thin film transistor (TFT) M3, the first electrode of the first film transistor M1 are electrical
It is connected to the second electrode of the second thin film transistor (TFT) M2 and the second electrode of the 6th thin film transistor (TFT) M6, the first film is brilliant
The second electrode of body pipe M1 be electrically connected at the 7th thin film transistor (TFT) M7 first electrode and the 8th thin film transistor (TFT) M8
The grid of two electrodes, the second thin film transistor (TFT) M2 and the 8th thin film transistor (TFT) M8 are electrically connected at the second scan control signal
The first electrode of S2, the second thin film transistor (TFT) M2 are electrically connected at data-signal VDATA, the third thin film transistor (TFT)
The grid of M3, the 4th thin film transistor (TFT) M4 and the 5th thin film transistor (TFT) M5 are electrically connected at the first scan control signal S1, described
The second electrode of third thin film transistor (TFT) M3 and the first electrode of the 4th thin film transistor (TFT) M4 are electrically connected at the 5th film crystal
The second electrode of the first electrode of pipe M5, the 4th thin film transistor (TFT) M4 is electrically connected at reference voltage signal VREF, described
The second electrode of 5th thin film transistor (TFT) M5 and the second electrode of the 7th thin film transistor (TFT) M7 are electrically connected at described shine
The anode of device L, the grid of the 6th thin film transistor (TFT) M6 and the grid of the 7th thin film transistor (TFT) M7 are electrically connected at third
The first electrode of scan control signal S3, the 6th thin film transistor (TFT) M6 are electrically connected at first voltage end VDD and described
The cathode of the other end of first capacitance C1, the luminescent device L is connected to second voltage end VSS.
The first film transistor M1 is driving thin film transistor (TFT), for driving Organic Light Emitting Diode OLED to shine.
The second thin film transistor (TFT) M2, third thin film transistor (TFT) M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5, the 6th
Thin film transistor (TFT) M6, the 7th thin film transistor (TFT) M7, the 8th thin film transistor (TFT) M8 are switching thin-film transistor.
According to the difference of transistor channel type, transistor can be divided into p channel transistor (being known as P-type transistor) and
N-channel transistor (is known as N-type transistor).In the present embodiment, the first film transistor M1, the second thin film transistor (TFT) M2,
Third thin film transistor (TFT) M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5, the 6th thin film transistor (TFT) M6, the 7th film
Transistor M7, the 8th thin film transistor (TFT) M8 are P-type transistor, and when low level is connected.Wherein, first electrode is source electrode, second
Electrode is drain electrode.It should be understood that the described first to the 8th thin film transistor (TFT) M1~M8 can also be different types of thin film transistor (TFT),
For example, first film transistor M1 is P-type transistor, and second to the 8th thin film transistor (TFT) M2~M8 is N-type transistor.Separately
Outside, according to the difference of transistor conductivity mode, the transistor in above-mentioned pixel circuit can be divided into enhancement transistor and consumption
Transistor npn npn to the greatest extent, following embodiment are by using the explanation carried out for p-type enhancement transistor.In addition, described first to
8th thin film transistor (TFT) M1~M8 can be low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) or oxide semiconductor thin-film transistor.
It is typically to use LTPS thin film transistor (TFT)s when using P-type transistor, is typically using oxide half when using N-type transistor
Conductor thin film transistor, naturally it is also possible to using the N-type transistor of low temperature polycrystalline silicon or the P-type crystal of oxide semiconductor
Pipe.
The luminescent device L can be in the prior art including LED (Light Emitting Diode, light emitting diode)
Or a variety of electric currents including OLED (Organic Light Emitting Diode, Organic Light Emitting Diode) drive photophore
Part.Following embodiment is by using the explanation carried out for OLED.
In the present embodiment, the voltage of first voltage end VDD inputs can be high voltage, second voltage end VSS inputs
Voltage can be low-voltage or ground terminal, and the voltage of reference voltage signal VREF inputs can be negative pressure.It should be understood that here
Relative size relationship between the high and low voltage for only indicating input.The first scan control signal S1, the second scan control letter
Number S2, third scan control signal S3 can be provided by external sequence controller.
Fig. 3 is the sequence diagram of pixel circuit in one embodiment of the invention.Picture in the present embodiment is described in detail below in conjunction with Fig. 3
The driving method of plain circuit.
As shown in figure 3, the pixel circuit realizes that threshold voltage compensation function includes three periods, respectively at the first time
Section t1, second time period t2 and third time period t 3.
In first time period t1, the first scan control signal S1 provides low level, in conjunction with shown in Fig. 4, in the first time
Section t1, first film transistor M1, third thin film transistor (TFT) M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5 conductings,
Utilize the anode electricity of the grid voltage and OLED of reference voltage signal VREF initialization first film transistors M1 (driving TFT)
Pressure.At this point, the voltage of first one end capacitance C1 is the voltage of reference voltage signal VREF, the voltage of the other end is first voltage end
The voltage of VDD.In first time period t1, the second scan control signal S2, third scan control signal S3 and data-signal
VDATA is provided which high level, the second thin film transistor (TFT) M2, the 6th thin film transistor (TFT) M6, the 7th thin film transistor (TFT) M7, the 8th film
Transistor M8 is closed, and control OLED does not shine.
In second time period t2, the second scan control signal S2 and data-signal VDATA are provided which low level, in conjunction with Fig. 5
It is shown, it is connected in second time period t2, first film transistor M1, the second thin film transistor (TFT) M2, the 8th thin film transistor (TFT) M8,
The source electrode of first film transistor M1 (driving TFT), the first film crystal can be written in the high level of data-signal VDATA inputs
The grid voltage of pipe M1 becomes VDATA-|Vth|, wherein VDATAFor the voltage of data-signal VDATA, VthFor first film transistor
The threshold voltage of M1.In the formula (- | Vth|) indicate that the threshold voltage of first film transistor M1 itself is negative value, this be because
It is the explanation carried out by taking p-type enhancement transistor as an example for the embodiment of the present invention, the threshold voltage of p-type enhancement transistor is negative
Value.At this point, the voltage of first one end capacitance C1 becomes VDATA-|Vth|, the voltage of the other end is the voltage of first voltage end VDD.
It is provided which high level, third film in second time period t2, the first scan control signal S1 and third scan control signal S3
Transistor M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5, the 6th thin film transistor (TFT) M6, the 7th thin film transistor (TFT) M7
It closes, control OLED does not shine.
In third time period t 3, third scan control signal S3 provides low level, and the first scan control signal S1, second are swept
It retouches control signal S2 and data-signal VDATA and is provided which high level.In conjunction with shown in Fig. 6, in the third time period t 3, the first film
Transistor M1, the 6th thin film transistor (TFT) M6, the 7th thin film transistor (TFT) M7 conductings, the second thin film transistor (TFT) M2, third film crystal
Pipe M3, the 4th thin film transistor (TFT) M4, the 5th thin film transistor (TFT) M5, the 8th thin film transistor (TFT) M8 are closed, and complete threshold voltage compensation,
OLED is driven to shine.At this point, the voltage of the first electrode (i.e. source electrode) of first film transistor M1 is the electricity of first voltage end VDD
Press VDD, grid voltage VDATA-|Vth|, source (the i.e. sources of first film transistor M1 gate voltage Vsg of first film transistor M1
Difference between pole tension and grid voltage) be：
Vsg=Vs-Vg=VDD-(VDATA-|Vth|)；
In the case, the electric current I of OLED is flowed throughOLEDFor：
IOLED=1/2 μ Cox·W/L·(Vsg-|Vth|)2=1/2 μ Cox·W/L·(VDD-VDATA)2
Wherein, μ is the electron mobility for driving TFT, CoxFor the capacitance between driving TFT gate and its channel, W/L is to drive
The channel breadth length ratio of dynamic TFT, VDDFor drive in actual work TFT first voltage end VDD voltage, VDATAFor data-signal
The voltage of VDATA.
From above formula as can be seen that flowing through the electric current I of light emitting diode OLEDOLEDOnly with first voltage end VDD and number
It is believed that number VDATA is related, and it is unrelated with the threshold voltage of driving TFT (first film transistor M1).Even if the drive of two pixels
The threshold voltage of dynamic TFT is different, and the electric current for flowing through part OLED of two pixels is also the same, the i.e. OLED of the two pixels
Brightness be the same.
It is found through experiment, when first film transistor M1 is to drive the threshold voltage of thin film transistor (TFT) relative to -1.5V points
When not drift ± 0.3V, the current changing rate for flowing through organic light emitting diode OLED is about 2.67%, flows through organic light emission two level
The electric current of pipe OLED is stablized, and the light emission luminance of Organic Light Emitting Diode OLED is uniform, so as to improve the display effect of picture.
In addition, since the pixel circuit is using third thin film transistor (TFT) M3, the 4th thin film transistor (TFT) M4, the 5th film crystal
The pattern of the gate series of pipe M5, advantageously reduce OLED initialization leakage current and driving TFT leakage current, a frame when
The interior fluctuation for reducing first film transistor M1 grid voltages, that is, reduce the fluctuation for flowing through OLED current, further increase
The consistency that screen body is shown.
Fig. 7 is the circuit diagram of another pixel circuit in the embodiment of the present invention.As shown in fig. 7, the pixel circuit
It can also be electrically connected at the grid of the second thin film transistor (TFT) M2, institute including one end of the second capacitance C2, the second capacitance C2
The other end for stating the second capacitance C2 is electrically connected at the grid of first film transistor M1, which can improve the first film crystalline substance
The grid voltage of body pipe M1 shields the electric current smaller of the dark-state of body, significantly improves the contrast of screen body, improves screen body display quality.
Foregoing description is only the description to present pre-ferred embodiments, not to any restriction of the scope of the invention, this hair
Any change, the modification that the those of ordinary skill in bright field does according to the disclosure above content, belong to the protection of claims
Range.
Claims (10)
1. a kind of pixel circuit, which is characterized in that including：First film transistor, the second thin film transistor (TFT), third film crystal
Pipe, the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT), the 8th film crystal
Pipe, the first capacitance and luminescent device；
Wherein, the grid of first film transistor be electrically connected at one end of the first capacitance, the 8th thin film transistor (TFT) first electricity
The first electrode of the first electrode of pole and third thin film transistor (TFT), first film transistor is electrically connected at the second film crystal
The second electrode of the second electrode of the second electrode of pipe and the 6th thin film transistor (TFT), first film transistor is electrically connected at
The second electrode of the first electrode of seven thin film transistor (TFT)s and the 8th thin film transistor (TFT)；Second thin film transistor (TFT) and the 8th film are brilliant
The grid of body pipe is electrically connected at one second scan control signal, and the first electrode of the second thin film transistor (TFT) is electrically connected at a number
It is believed that number；The grid of third thin film transistor (TFT), the 4th thin film transistor (TFT) and the 5th thin film transistor (TFT) is electrically connected at one first and sweeps
Retouch control signal, it is thin that the first electrode of the second electrode of third thin film transistor (TFT) and the 4th thin film transistor (TFT) is electrically connected at the 5th
The first electrode of film transistor；The second electrode of 4th thin film transistor (TFT) is electrically connected at a reference voltage signal；5th film
The second electrode of transistor and the second electrode of the 7th thin film transistor (TFT) are electrically connected at the anode of luminescent device；6th is thin
The grid of the grid of film transistor and the 7th thin film transistor (TFT) is electrically connected at a third scan control signal, the 6th film crystal
The first electrode of pipe is electrically connected at the other end of a first voltage end and the first capacitance；The cathode of luminescent device is connected to one
Second voltage end.
2. pixel circuit as described in claim 1, which is characterized in that the first film transistor, the second thin film transistor (TFT),
Third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT) with
And the 8th thin film transistor (TFT) be P-type transistor.
3. pixel circuit as described in claim 1, which is characterized in that the first film transistor, the second thin film transistor (TFT),
Third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th thin film transistor (TFT), the 6th thin film transistor (TFT), the 7th thin film transistor (TFT) with
And the 8th thin film transistor (TFT) be low-temperature polysilicon film transistor.
4. pixel circuit as described in claim 1, which is characterized in that the first electrode is source electrode, and the second electrode is
Drain electrode；Alternatively, the first electrode is drain electrode, the second electrode is source electrode.
5. pixel circuit as described in claim 1, which is characterized in that first scan control signal, the second scan control
Signal, third scan control signal are provided by external sequence controller.
6. pixel circuit as described in claim 1, which is characterized in that the luminescent device is OLED.
7. such as any one of claim 1 to 6 to the pixel circuit, which is characterized in that further include the second capacitance, described the
One end of two capacitances is electrically connected at the grid of the second thin film transistor (TFT), and the other end of second capacitance is electrically connected at first
The grid of thin film transistor (TFT).
8. a kind of display device, which is characterized in that using the pixel circuit as described in any one of claim 1 to 7.
9. a kind of driving method of pixel circuit as described in any one of claim 1 to 7, which is characterized in that including：
In first time period, first film transistor, third thin film transistor (TFT), the 4th thin film transistor (TFT), the 5th thin film transistor (TFT)
Conducting, utilizes the grid voltage of reference voltage initialization signal first film transistor and the anode voltage of luminescent device；
In second time period, first film transistor, the second thin film transistor (TFT), the conducting of the 8th thin film transistor (TFT), the first film is brilliant
The grid voltage of body pipe becomes VDATA-|Vth|, wherein VDATAFor the voltage of data-signal, VthFor the threshold of first film transistor
Threshold voltage；
In the third period, first film transistor, threshold value electricity is completed in the 6th thin film transistor (TFT), the conducting of the 7th thin film transistor (TFT)
Pressure compensation, driving luminescent device shine.
10. the driving method of pixel circuit as claimed in claim 9, which is characterized in that in first time period, the first scanning control
Signal processed provides low level, and the second scan control signal, third scan control signal and data-signal provide high level；Second
Period, the second scan control signal and data-signal provide low level, the first scan control signal and third scan control letter
Number it is provided which high level；In the third period, third scan control signal provides low level, the first scan control signal, second
Scan control signal and data-signal are provided which high level.
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| CN201710125364.6A CN108538251A (en) | 2017-03-04 | 2017-03-04 | Pixel circuit and its driving method, display device |
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| CN201710125364.6A CN108538251A (en) | 2017-03-04 | 2017-03-04 | Pixel circuit and its driving method, display device |
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| CN201710125364.6A Pending CN108538251A (en) | 2017-03-04 | 2017-03-04 | Pixel circuit and its driving method, display device |
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| CN108735161A (en) * | 2018-05-25 | 2018-11-02 | 昆山国显光电有限公司 | Pixel circuit and its driving method, OLED display panel and display device |
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