CN110164383A - A kind of pixel circuit and display device - Google Patents
A kind of pixel circuit and display device Download PDFInfo
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- CN110164383A CN110164383A CN201810877288.9A CN201810877288A CN110164383A CN 110164383 A CN110164383 A CN 110164383A CN 201810877288 A CN201810877288 A CN 201810877288A CN 110164383 A CN110164383 A CN 110164383A
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- 239000013078 crystal Substances 0.000 description 6
- 230000003760 hair shine Effects 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 238000003483 aging Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
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- 230000003287 optical effect Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
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- 238000005401 electroluminescence Methods 0.000 description 1
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- 239000004973 liquid crystal related substance Substances 0.000 description 1
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- 239000004065 semiconductor Substances 0.000 description 1
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Classifications
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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
-
- 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]
- G09G3/3275—Details of drivers for data electrodes
- G09G3/3291—Details of drivers for data electrodes in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
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- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
The present invention relates to a kind of pixel circuit and display device, the pixel circuit includes: charge control module, is suitable for receiving charging control signal, and charge to control node using data voltage according to the charging control signal；Operating current generation module, the operating current generation module are suitable for generating operating current according to the voltage of the control node；Light emitting control module is connected with the operating current generation module, and the light emitting control module is suitable for being controlled whether the operating current being provided to luminescent device according to LED control signal；Current potential clamps down on module, connects with the operating current generation module, and the current potential clamps down on the voltage that module is suitable for clamping down on the output end of the operating current generation module.Technical solution of the present invention shows non-uniform phenomenon caused by being effectively improved due to the photoelectric attenuation of OLED.
Description
Technical field
The present invention relates to technical field of display panel more particularly to a kind of pixel circuit and display devices.
Background technique
Organic electroluminescence device (OLED) is the total solids device that electric energy is directly changed into luminous energy, due to it is with thin
Gently, cause very big concern in the industry the advantages that high contrast, quick response, wide viewing angle, wide operating temperature range, it is considered to be
Display device of new generation.
In the pixel circuit of existing driving OLED, OLED is after using the regular hour, it may appear that aging phenomenon, i.e. light
Electric attenuation.After OLED aging, the cross-pressure between OLED anode and cathode is increased, and affects the electricity of driving transistor output
Pressure, the operating current for generating it reduce.That is, the brightness of OLED can be dimmed when inputting identical data voltage, by
It is different in the degree of each OLED aging, it will appear the bright dark different phenomenon of regional area on display.
Currently, shown caused by due to photoelectric attenuation non-uniform phenomenon be the key that restrict OLED to large screen development because
Element.Show that non-uniform phenomenon is urgently to be resolved during pixel circuit design caused by how improving due to the photoelectric attenuation of OLED
The problem of.
Summary of the invention
Present invention solves the technical problem that be how to improve due to the photoelectric attenuation of OLED caused by show non-uniform phenomenon.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of pixel circuit, comprising: charge control module is fitted
In reception charging control signal, and charged using data voltage to control node according to the charging control signal；Work
Electric current generation module, the operating current generation module are suitable for generating operating current according to the voltage of the control node；It shines
Control module is connected with the operating current generation module, and the light emitting control module is suitable for being controlled according to LED control signal
Whether the operating current is provided to luminescent device；Current potential clamps down on module, connects with the operating current generation module, described
Current potential clamps down on the voltage that module is suitable for clamping down on the output end of the operating current generation module.
Optionally, the operating current generation module includes: drive module, described in the control terminal connection of the drive module
Control node, suitable for generating operating current according to the voltage of the control node；Voltage keeps module, and the voltage keeps module
Suitable for keeping the voltage of the control terminal of the drive module after the data voltage stops to control node charging.
Optionally, the drive module includes the first transistor, and the source electrode of the first transistor is via light emitting control mould
Block is connect with power supply, and the grid of the first transistor is the control terminal of the drive module, the first transistor
Drain electrode is the output end of the drive module.
Optionally, it includes capacitor that the voltage, which keeps module, the first pole plate of the capacitor and the control of the drive module
End connection processed, the second pole plate of the capacitor are connect with power supply.
Optionally, the light emitting control module includes second transistor, and the grid of the second transistor receives the hair
The drain electrode of optical control signal, the second transistor is connect with the input terminal of the operating current generation module, and described second is brilliant
The source electrode of body pipe is connect with power supply.
Optionally, it includes third transistor that the current potential, which clamps down on module, the source electrode of the third transistor and the work
The output end of electric current generation module connects, and the drain electrode of the third transistor connects the luminescent device, the third transistor
Grid receive bias voltage.
Optionally, the bias voltage is DC voltage or pulse voltage.
Optionally, the charge control module includes the 4th transistor, is filled described in the grid reception of the 4th transistor
Electric control signal, the source electrode of the 4th transistor receive the data voltage, described in the drain electrode connection of the 4th transistor
Control node.
Optionally, the pixel circuit further include: the 5th transistor, the grid of the 5th transistor, which receives, resets control
Signal, the source electrode of the 5th transistor receive resetting voltage, and the drain electrode of the 5th transistor connects the luminescent device.
In order to solve the above technical problems, the embodiment of the invention also provides a kind of display device, the display device includes
Pixel circuit above-mentioned.
Compared with prior art, the technical solution of the embodiment of the present invention has the advantages that
The pixel circuit of technical solution of the present invention includes charge control module, suitable for reception charging control signal, and according to
The charging control signal charges to control node using data voltage；Operating current generation module, the operating current
Generation module is suitable for generating operating current according to the voltage of the control node；Light emitting control module, it is raw with the operating current
At block coupled in series, the light emitting control module is suitable for being controlled whether the operating current being provided to hair according to LED control signal
Optical device；Current potential clamps down on module, connects with the operating current generation module, and the current potential clamps down on module and is suitable for clamping down on the work
Make the voltage of the output end of electric current generation module.Thus, it is possible to which it is defeated to clamp down on operating current generation module when OLED cross-pressure increases
The voltage of outlet can be effectively improved and cause because of the photoelectric attenuation of OLED so as to keep operating current hardly to change
OLED show non-uniform phenomenon.
Further, the drive module includes the first transistor, and the source electrode of the first transistor is via light emitting control mould
Block is connect with power supply, and the grid of the first transistor receives data voltage, and the drain electrode of the first transistor is driving
The output end of module；It includes third transistor that the current potential, which clamps down on module, the source electrode of the third transistor and first crystalline substance
The drain electrode of body pipe connects, and the drain electrode of the third transistor connects the luminescent device, and the grid of the third transistor receives
Bias voltage.The third transistor and the first transistor form cascode structure as a result, can effectively clamp down on driving
The voltage of the output end of module.
Further, the pixel circuit of technical solution of the present invention further includes the 5th transistor, the grid of the 5th transistor
Reseting controling signal is received, the source electrode of the 5th transistor receives resetting voltage, and the drain electrode of the 5th transistor connects institute
State luminescent device.Thus, it is possible to be resetted after the display of previous frame signal to the luminescent device of pixel circuit, effectively drop
Low influence of the previous frame signal to next frame signal.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of pixel circuit in the prior art；
Fig. 2 is data voltage-operating current relation curve after the light emitting device aging preceding and aging of pixel circuit in Fig. 1
Comparison diagram；
Fig. 3 is that operating current deviation-data voltage of the luminescent device of pixel circuit in Fig. 1 under different degree of agings closes
It is curve synoptic diagram；
Fig. 4 is a kind of structural schematic diagram of pixel circuit of the embodiment of the present invention；
Fig. 5 is that operating current deviation-data voltage of the luminescent device of pixel circuit in Fig. 4 under different degree of agings closes
It is curve synoptic diagram.
Specific embodiment
It is understandable to enable above-mentioned purpose of the invention, feature and beneficial effect to become apparent, with reference to the accompanying drawing to existing
There are technology and specific embodiments of the present invention to be described in detail.Obviously, described embodiment is only the present invention one
Divide embodiment, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not making
Every other embodiment obtained, belongs to protection scope of the present invention under the premise of creative work.
Fig. 1 is a kind of structural schematic diagram of pixel circuit in the prior art.Fig. 2 is the luminescent device of pixel circuit in Fig. 1
Data voltage-operating current relation curve comparison diagram before aging and after aging；Fig. 3 is the luminescent device of pixel circuit in Fig. 1
Operating current deviation-data voltage relation curve schematic diagram under different degree of agings.
Referring to FIG. 1, pixel circuit in the prior art includes the first transistor P1, second transistor P2, third crystal
Pipe P3, the 4th transistor P4, capacitor C and luminescent device OLED, wherein the source electrode of the first transistor P1 is via second transistor
The anode of the drain electrode connection luminescent device OLED of P2 connection power supply PVDD, the first transistor P1, the yin of luminescent device OLED
Pole connects negative pressure end PVEE, and the grid of the first transistor P1 receives data voltage Vdata via third transistor P3；4th crystal
The source electrode of pipe P4 receives resetting voltage Vf, the anode of the drain electrode connection luminescent device OLED of the 4th transistor；The first pole of capacitor C
Plate is connect with the grid of the first transistor P1, and the second pole plate of capacitor C is connect with power supply PVDD.
In reseting stage, setting reseting controling signal SCAN1 is low level, and LED control signal EMIT is high level, is filled
Electric control signal SCAN2 is high level.At this point, second transistor P2 is turned off, third transistor P3 shutdown, the 4th transistor P4 is led
It is logical.The anode of luminescent device OLED receives resetting voltage Vf, the reset to luminescent device OLED is completed, to eliminate previous frame signal
Influence to next frame signal.
Data phase is being write, setting charging control signal SCAN2 is low level, and LED control signal EMIT is high level,
Reseting controling signal SCAN1 is high level.Second transistor P2 shutdown, third transistor P3 conducting, the 4th transistor P4 shutdown,
Gate charges of the data voltage Vdata to the first transistor.
Then, setting charging control signal SCAN2 is low level, second transistor P2 shutdown, the first transistor P1
Grid voltage kept by capacitor C.
In light emitting phase, setting charging control signal SCAN2 is high level, and LED control signal EMIT is low level, multiple
Position control signal is high level.Then the second transistor P2 conducting, third transistor P3 shutdown, the 4th transistor P4 shutdown.
The operating current as corresponding to the grid voltage of the capacitor C the first transistor P1 kept flows to luminescent device OLED, shines
Device OLED shines.
Referring to FIG. 2, after OLED aging, it may occur that photoelectric attenuation phenomenon, at this point, the anode voltage V of OLED0With cathode
Pressure difference between voltage increases, that is to say, that the cross-pressure of OLED increases.Due to the drain electrode of the anode and the first transistor P1 of OLED
Connection, therefore, the drain voltage of the first transistor increase, and lead to the drain electrode of the first transistor P1 and the source electrode of the first transistor P1
Between voltage difference reduce, flow into OLED operating current reduce.If maintaining identical operating current I0, then need to provide
Bigger data voltage Vdata2, if data voltage remains as the data voltage Vdata1, then OLED when OLED is worked normally
Brightness it is dimmed, cause display uneven.
Referring to FIG. 3, operating current when showing oled light electric attenuation 100mV, 200mV, 300mV, 400mV in Fig. 3
Deviation-data voltage relation curve.The percentage of the operating current deviation is the departure and original operating current of operating current
Ratio.The degree of OLED aging is more serious it can be seen from change curve, i.e. the degree of photoelectric attenuation is bigger, then aging it
The deviation of operating current and original state afterwards is bigger, and the OLED dimmed situation that shines is more serious.
Current potential is arranged in pixel circuit and clamps down on module for technical solution of the present invention, with the operating current generation module string
Connection, the current potential clamp down on the voltage that module is suitable for keeping the output end of the operating current generation module.The current potential clamps down on mould
Block can reduce influence of the photoelectric attenuation of OLED to operating current generation module, keep driving current when OLED cross-pressure increases
It is almost unchanged, it is shown unevenly so as to improve brightness caused by due to the photoelectric attenuation of OLED.
Fig. 4 is a kind of structural schematic diagram of pixel circuit of the embodiment of the present invention.
Referring to FIG. 4, the pixel circuit may include: charge control module 1, it is suitable for receiving charging control signal
SCAN2, and charged using data voltage Vdata to control node N according to the charging control signal SCAN2；Work electricity
Generation module 2 is flowed, the operating current generation module 2 is suitable for generating operating current according to the voltage of the control node N；It shines
Control module 4 is connected with the operating current generation module 2, and the light emitting control module 4 is suitable for according to LED control signal
EMIT controls whether the operating current being provided to luminescent device OLED；Current potential clamps down on module 3, generates with the operating current
Module 2 is connected, and the current potential clamps down on the voltage that module 3 is suitable for clamping down on the output end of the operating current generation module 2.
In the present embodiment, the data voltage Vdata can be the voltage of fixed voltage value, and it is adjustable to be also possible to voltage value
Voltage, to adapt to the luminous demand of different luminescent device OLED, those skilled in the art can be according to specific requirements and application
The voltage value of the setting data voltage Vdata of occasion and adaptability, the embodiment of the present invention are without limitation.
Specifically, the charging control signal SCAN2 can be level signal, such as: charging control signal SCAN2 is low
When level, it can control charge control module 1 and do not work；When electric control signal SCAN2 is high level, charge control can control
Module 1 is started to work.
Specifically, LED control signal EMIT can be level signal, such as: LED control signal EMIT is low level
When, it can control light emitting control module 4 and do not work；When LED control signal EMIT is high level, light emitting control mould can control
Block 4 is started to work.
Specifically, the luminescent device OLED can be light emitting diode.The anode of the light emitting diode can be via
Current potential is clamped down on module 3 and is connect with operating current generation module 2, and the cathode of the light emitting diode can meet negative pressure PVSS.
More specifically, the light emitting diode can be organic electroluminescent LED.
It should be noted that the pixel circuit of the embodiment of the present invention can be used for powering for various types of luminescent devices,
The embodiment of the present invention to the type of luminescent device OLED with no restrictions.
In the present embodiment, the current potential clamps down on the electricity that module 3 is suitable for clamping down on the output end of the operating current generation module 2
Pressure refers to that when the other parameters variable in pixel circuit changes, the voltage of 2 output end of operating current generation module can be one
A expected micro- a small range changes.In the lower application of precise requirements, the expected small range can
To ignore.Accordingly it is also possible to think that operating current is barely affected, that is to say, that the brightness change of luminescent device OLED
It can be ignored for visually observing.It is caused thus, it is possible to be effectively improved because of the photoelectric attenuation of luminescent device OLED
Display non-uniform phenomenon.
Further, the operating current generation module 2 may include: drive module 201, the drive module 201
Control terminal connects the control node N, suitable for generating operating current according to the voltage of the control node N；Voltage keeps module
202, the voltage keeps module 202 to be suitable for after the data voltage Vdata stops to control node N charging, keeps
The voltage of the control terminal of the drive module 201.
Specifically, the output end of the operating current generation module 2 is exactly the port of output services electric current, from the port flow
Operating current out can flow into luminescent device OLED, and driving luminescent device OLED shines.
Further, the drive module 201 may include the first transistor P1, the source electrode warp of the first transistor P1
It is connect by light emitting control module 4 with power supply PVDD, the grid of the first transistor P1 is the control of the drive module 201
End processed, the drain electrode of the first transistor P1 are the output end of the drive module 201.
Further, it may include capacitor C that the voltage, which keeps module 202, the first pole plate of the capacitor C and the drive
The control terminal of dynamic model block 201 connects, and the second pole plate of the capacitor C is connect with power supply PVDD.In the drive module 201
Control terminal Voltage Establishment complete after, the capacitor C is used to keep the control terminal voltage of the drive module 201.
Further, the light emitting control module 4 may include second transistor P2, the grid of the second transistor P2
Receive the LED control signal EMIT, the drain electrode and the input of the operating current generation module 2 of the second transistor P2
End connection, the source electrode of the second transistor P2 are connect with power supply PVDD.
Specifically, the LED control signal EMIT can be level signal, such as: LED control signal EMIT is low electricity
Usually, it can control second transistor P2 conducting；When LED control signal EMIT is high level, second transistor P2 can control
Shutdown.
Further, it may include third transistor P3 that the current potential, which clamps down on module 3, the source electrode of the third transistor P3
It is connect with the output end of the operating current generation module 2, the drain electrode of the third transistor P3 connects the luminescent device
The grid of OLED, the third transistor P3 receive bias voltage Vbias.
Specifically, the bias voltage Vbias can be DC voltage or pulse voltage.
Further, the bias voltage Vbias can be the voltage of fixed voltage value, and it is adjustable to be also possible to voltage value
Voltage, to adapt to the luminous demand of different luminescent device OLED, those skilled in the art can be according to specific requirements and applied field
It closes and the voltage value of the setting bias voltage Vbias of adaptability, the embodiment of the present invention is without limitation.
Further, the charge control module 1 may include the 4th transistor P4, the grid of the 4th transistor P4
Receiving the charging control signal SCAN2, the source electrode of the 4th transistor P4 receives the data voltage Vdata, and described the
The drain electrode of four transistor P4 connects the control node N.Since control node N is also connected with the grid of the first transistor P1
Pole, therefore, the grid of the first transistor P1 are connect with the drain electrode of the 4th transistor P4.
Specifically, the charging control signal SCAN2 can be level signal, such as: charging control signal SCAN2 is low
When level, the 4th transistor P4 conducting can control, at this point, the grid of the first transistor P1 can receive data voltage Vdata；
When charging control signal SCAN2 high level, the 4th transistor P4 shutdown can control, the grid of the first transistor P1 is prevented to continue
Receive data voltage Vdata.
Further, the pixel circuit can also include: reseting module 5, and the reseting module 5 may include the 5th crystalline substance
The grid of body pipe P5, the 5th transistor P5 receive reseting controling signal SCAN1, and the source electrode of the 5th transistor P5 receives
The drain electrode of resetting voltage Vf, the 5th transistor P5 connect the luminescent device OLED.
Specifically, the reseting controling signal SCAN1 can be level signal, such as: reseting controling signal SCAN1 is low
When level, the 5th transistor P5 conducting can control；When reseting controling signal SCAN1 is high level, the 5th crystal can control
Pipe P5 shutdown.
Further, the resetting voltage Vf can be less than the cut-in voltage of luminescent device OLED, to guarantee photophore
Part OLED will not be opened in reseting stage by opening by mistake.
Thus, it is possible to be resetted after the display of previous frame signal to the luminescent device of pixel circuit, it is effectively reduced
Influence of the previous frame signal to next frame signal.
In a non-limiting embodiment, for example, the pixel circuit can be used for driving micro- light emitting diode
Mirco-OLED.Micro- light emitting diode Mirco-OLED is the luminescent device made based on silicon substrate, can regard as by
OLED it is miniature to original 1% and obtain, length is usually at 100 μm or less.The display electricity of micro- light emitting diode Mirco-OLED
Road and driving circuit can integrate in silicon substrate.Due to the luminous operating current ratio needed of micro- light emitting diode Mirco-OLED
Smaller, therefore, the driving tube for generating operating current only needs work to be just able to satisfy micro- light emitting diode Mirco- in sub-threshold region
OLED luminous demand.
In pixel circuit, the calculation formula of the operating current of micro- light emitting diode Mirco-OLED can be indicated are as follows:
Wherein, I is the operating current for flowing through OLED；M is sub-threshold region coefficient, with the driving crystal for generating operating current
The technological parameter and size of pipe are related, and m > 1；μ eff is semiconductor mobility；Cox is oxidation layer capacitance；W is to generate work
The channel width of the driving transistor of electric current；L is the channel length for generating the driving transistor of operating current；Vt is thermoelectrical potential；
Vsg is the voltage generated between the grid and source electrode of the driving tube of operating current；Vtp is the threshold for generating the driving tube of operating current
Threshold voltage；Vsd is the voltage generated between the source electrode and drain electrode of the driving tube of operating current；K be Boltzmann constant (1.38 ×
10-23J/K)；T is thermodynamic temperature, i.e. absolute temperature；Q is electron charge (1.6 × 10-19C).At normal temperature, Vt ≈ 26mV.
It is exponential relationship between the operating current I and Vsg that driving transistor generates, Vsd it can be seen that in sub-threshold region,
The voltage of transistor is driven to have small variation, the acute variation of electric current will be caused.
When driving micro- light emitting diode Mirco-OLED to work using pixel circuit shown in Fig. 4, generation work above-mentioned
Make the first transistor P1 in the driving tube i.e. Fig. 4 of electric current, luminescent device OLED can be micro- light emitting diode at this time
Mirco-OLED。
Course of work when driving micro- light emitting diode Mirco-OLED to shine the pixel circuit below carries out detailed
Explanation.
In reseting stage, setting reseting controling signal is that SCAN1 is low level, and LED control signal EMIT is high level,
Charging control signal SCAN2 is high level.
In reseting stage, second transistor P2, the 4th transistor P4 shutdown, the 5th transistor P5 conducting.Micro- light-emitting diodes
The anode of pipe Mirco-OLED receives resetting voltage Vf.That is, the anode voltage V of micro- light emitting diode Mirco-OLED0
Equal to resetting voltage Vf, the cut-in voltage that resetting voltage Vf is less than micro- light emitting diode Mirco-OLED is set, then it is micro- to shine two
Pole pipe Mirco-OLED does not shine in reseting stage.
Display state influence caused by the display state of next frame pixel of previous frame pixel can be eliminated by resetting operation.
Data phase is being write, setting LED control signal EMIT is high level, and reseting controling signal SCAN1 is high level,
Charging control signal SCAN2 is low level, and Vbias is DC offset voltage.
Writing data phase, the 4th transistor P4 conducting, second transistor P2, the 5th transistor P5 shutdown.First crystal
The grid of pipe P1 receives data voltage Vdata, and the grid of third transistor P3 receives bias voltage Vbias.
Then, setting charging control signal SCAN2 is low level, second transistor P4 shutdown, the first transistor P1
Grid voltage kept by capacitor C.
In light emitting phase, setting LED control signal EMIT is low level, and charging control signal SCAN2 is high level, multiple
Position control signal SCAN1 is high level, and Vbias is DC offset voltage.
In light emitting phase, second transistor P2 conducting, the 4th transistor P4 shutdown, the 5th transistor P5 shutdown.First is brilliant
The grid voltage of body pipe P1 can control the first transistor P1 work in sub-threshold region, and bias voltage Vbias can control third
Transistor P3 works in sub-threshold region.The operating current (i.e. sub-threshold current) that the first transistor P1 in sub-threshold region that works is generated
Micro- light emitting diode Mirco-OLED is flowed into, micro- light emitting diode Mirco-OLED is driven to shine.
It will be understood by those skilled in the art that controlling the first transistor P1 work in the grid voltage of sub-threshold region by data
Voltage Vdata is provided, and the voltage value size of the data voltage Vdata and bias voltage Vbias correspond to the work of transistor
Make state and is arranged in advance.
Micro- light emitting diode Mirco-OLED work is after a certain period of time, it may occur that aging phenomenon, i.e. photoelectric attenuation.It is right
For same operating current, brightness can become micro- light emitting diode Mirco-OLED after aging under identical condition
Secretly, while the cross-pressure of micro- light emitting diode Mirco-OLED can also increase.
In the pixel circuit, the grid of the first transistor P1 receives data voltage Vdata as input terminal, and first
The source electrode of transistor P1 connects third crystal via the drain electrode of second transistor P2 connection power supply PVDD, the first transistor P1
The source electrode of pipe P3, the grid of third transistor P3 receive the bias voltage Vbias of fixed voltage value.Therefore, the first transistor P1
Cascade structure with third transistor P3 is the structure of cascade, and such cascade structure can clamp down on the first transistor P1
Drain voltage.In the cascode structure that the first transistor P1 and third transistor P3 is constituted, the first transistor P1 is suitable
Common source pipe in the cascode structure, third transistor P3 are equivalent to the total bank tube in the cascode structure.?
In the pixel circuit with cascode structure, though between micro- light emitting diode Mirco-OLED anode and cathode across
Pressure increases, and the drain voltage change of the first transistor P1 is also very small, can almost remain unchanged, that is to say, that plays driving and makees
The operating current that the first transistor P1 is generated also substantially remains unchanged.
Referring to FIG. 5, Fig. 5 is shown the case where the first transistor P1 and third transistor P3 constitutes cascode structure
Under, operating current deviation-data electricity when micro- light emitting diode Mirco-OLED photoelectric attenuation 100mV, 200mV, 300mV, 400mV
Press relation curve.Wherein, the percentage of operating current deviation is the departure of operating current and the ratio of former operating current.It is corresponding
In the different photoelectric attenuation degree of micro- light emitting diode Mirco-OLED, the work electricity of micro- light emitting diode Mirco-OLED is flowed into
It is very small to flow deviation.That is, the brightness change of micro- light emitting diode Mirco-OLED is very before and after photoelectric attenuation generation
It is small, it can be ignored for visually observing, to significantly improve because micro- light emitting diode Mirco-OLED photoelectricity declines
Subtract and caused by show non-uniform phenomenon.
It will be appreciated by those skilled in the art that above-mentioned pixel circuit is not limited to improve micro- light emitting diode Mirco-
The photoelectric attenuation of OLED can be used for improving the photoelectric attenuation of the luminescent device of any type and volume.
Further, the embodiment of the invention also discloses a kind of display devices comprising pixel circuit shown in Fig. 4 or
Any pixel circuit referred in the associated description of Fig. 4.
Specifically, it is aobvious to can be liquid crystal display (LCD), plasma display (PDP), field emission for the display device
Show device (FED), electroluminescent display (ECD), electrochromic display device (ECD) (ECD), laser writer (LPD) etc..
The display device is shown using pixel circuit above-mentioned and is improved the detailed process explanation of photoelectric attenuation
It may refer to the associated description of the pixel circuit in above-mentioned embodiment illustrated in fig. 4, details are not described herein.
It should be noted that each transistor in pixel circuit described in the embodiment of the present invention can be P-type transistor,
It can be N-type transistor, those skilled in the art can be according to the selection of specific application and device cost and adaptability
The concrete type of transistor, the embodiment of the present invention are without limitation.
It should be noted that the voltage value of " high level " and " low level " in the embodiment of the present invention does not do specific limit
It is fixed, as long as the voltage value of high level is higher than low level voltage value.For example, the voltage value of high level can be identified as patrolling
1 is collected, and low level voltage value can be identified as logical zero.
Although present disclosure is as above, present invention is not limited to this.Anyone skilled in the art are not departing from this
It in the spirit and scope of invention, can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the range of restriction.
Claims (10)
1. a kind of pixel circuit characterized by comprising
Charge control module is suitable for receiving charging control signal, and utilizes data voltage to control according to the charging control signal
Node processed charges；
Operating current generation module, the operating current generation module are suitable for generating work electricity according to the voltage of the control node
Stream；
Light emitting control module is connected with the operating current generation module, and the light emitting control module is suitable for according to light emitting control
Signal controls whether the operating current being provided to luminescent device；
Current potential clamps down on module, connects with the operating current generation module, and the current potential clamps down on module and is suitable for clamping down on the work
The voltage of the output end of electric current generation module.
2. pixel circuit according to claim 1, which is characterized in that the operating current generation module includes:
The control terminal of drive module, the drive module connects the control node, suitable for the voltage according to the control node
Generate operating current；
Voltage keeps module, and the voltage keeps module to be suitable for after the data voltage stops to control node charging,
Keep the voltage of the control terminal of the drive module.
3. pixel circuit according to claim 2, which is characterized in that the drive module includes the first transistor, described
The source electrode of the first transistor is connect via light emitting control module with power supply, and the grid of the first transistor is the driving
The control terminal of module, the drain electrode of the first transistor are the output end of the drive module.
4. pixel circuit according to claim 2, which is characterized in that it includes capacitor that the voltage, which keeps module, the electricity
The first pole plate held is connect with the control terminal of the drive module, and the second pole plate of the capacitor is connect with power supply.
5. pixel circuit according to claim 1, which is characterized in that the light emitting control module includes second transistor,
The grid of the second transistor receives the LED control signal, and the drain electrode of the second transistor and the operating current are raw
It is connected at the input terminal of module, the source electrode of the second transistor is connect with power supply.
6. pixel circuit according to claim 1, which is characterized in that it includes third transistor that the current potential, which clamps down on module,
The source electrode of the third transistor is connect with the output end of the operating current generation module, and the drain electrode of the third transistor connects
The luminescent device is connect, the grid of the third transistor receives bias voltage.
7. pixel circuit according to claim 6, which is characterized in that the bias voltage is DC voltage or pulse electricity
Pressure.
8. pixel circuit according to claim 1, which is characterized in that the charge control module includes the 4th transistor,
The grid of 4th transistor receives the charging control signal, and the source electrode of the 4th transistor receives the data electricity
The drain electrode of pressure, the 4th transistor connects the control node.
9. pixel circuit according to claim 1, which is characterized in that further include: the 5th transistor, the 5th transistor
Grid receive reseting controling signal, the source electrode of the 5th transistor receives resetting voltage, the drain electrode of the 5th transistor
Connect the luminescent device.
10. a kind of display device, which is characterized in that the display device includes the described in any item pixel electricity of claim 1-9
Road.
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|---|---|---|---|
| CN201810877288.9A CN110164383A (en) | 2018-08-03 | 2018-08-03 | A kind of pixel circuit and display device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810877288.9A CN110164383A (en) | 2018-08-03 | 2018-08-03 | A kind of pixel circuit and display device |
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