CN103606351A - Active matrix organic light emitting diode pixel drive circuit and driving method thereof - Google Patents
Active matrix organic light emitting diode pixel drive circuit and driving method thereof Download PDFInfo
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- CN103606351A CN103606351A CN201310629215.5A CN201310629215A CN103606351A CN 103606351 A CN103606351 A CN 103606351A CN 201310629215 A CN201310629215 A CN 201310629215A CN 103606351 A CN103606351 A CN 103606351A
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Abstract
The invention provides an active matrix organic light emitting diode pixel drive circuit and a driving method thereof. The drive circuit comprises a first transistor, a second transistor, a third transistor, drive transistors, a compensation capacitor and an organic light emitting diode, wherein embedded tunneling field-effect tubes are arranged on the drive transistors and can be used for changing threshold voltages of the drive transistors so as to change the magnitude of drive currents, unevenness of threshold voltages of the pixel drive transistors is compensated, the area of a single pixel is reduced, and improvement of the aperture opening ratio is facilitated.
Description
Technical field
The pixel driver technology that the present invention relates to light emitting diode indicator, particularly relates to active matrix organic light-emitting diode pixel-driving circuit and driving method thereof.
Background technology
Building-out capacitor active matrix organic light-emitting diode (Active Matrix/Organic Light Emitting Diode, AMOLED) display is one of focus of current flat-panel monitor research field, compare with traditional Organic Light Emitting Diode, active matrix organic light-emitting diode has low energy consumption, wide visual angle, responds fast, contrast advantages of higher.
The thin film transistor (TFT) adopting in the pixel of active matrix organic light-emitting diode is mainly divided into two kinds of hydrogenation non crystal silicon film transistor (a-Si:H TFT) and low-temperature polysilicon film transistors (LTPS TFT), due to the difference of material nature, the carrier mobility of a-Si:H TFT is lower than LTPS TFT's.Compare with adopting the pixel of LTPS TFT, adopt the pixel of a-Si:H TFT need to strengthen device size, and improve driving voltage, could realize the driving effect identical with LTPS TFT, still, also can cause thus the aperture opening ratio of pixel and device lifetime to be reduced.Therefore, adopt the active matrix organic light-emitting diode device of LTPS TFT to there is obvious advantage.
Due to the deviation of Practical manufacturing technique, the threshold voltage of the driving tube TFT in pixel and carrier mobility are also incomplete same.If do not adopt compensation technique, the difference of pixel driver device parameter will cause showing that brightness of image is inhomogeneous, thereby cause the decline of image displaying quality.In addition, along with the accumulation of working time, device will be aging, and the threshold voltage of drive TFT can increase, and under identical voltage signal, the drive current of drive TFT diminishes, thereby affect the overall brightness of image.
In order to address the above problem, people have proposed a variety of compensation schemes, as one of comparatively typical compensation scheme in prior art, the Chinese patent that application number is 201010522409.1, name is called " pixel-driving circuit of active organic electroluminescent display and driving method thereof " has proposed a kind of pixel-driving circuit of compensating action, and Fig. 1 and Fig. 2 are respectively active matrix organic light-emitting diode pixel-driving circuit structural representation and the corresponding sequential schematic diagram that drives in prior art.As Fig. 1, shown in Fig. 2, in this scheme, active matrix organic light-emitting diode pixel-driving circuit comprises a driving transistors T2, four switching transistor T1, T3, T4, T5, a coupling capacitance C1, a building-out capacitor C2 and an Organic Light Emitting Diode OLED, the first transistor T1 control coupling capacitance C1 is that the grid of driving transistors T2 writes gradation data voltage Vdata, driving transistors T2 is used for driving Organic Light Emitting Diode OLED luminous, the 3rd transistor T 3 provides charging path by the 4th transistor T 4, by driving transistors, T2 provides discharge path, it is luminous that the 4th transistor T 4 is controlled Organic Light Emitting Diode OLED by driving transistors T2, the 5th transistor T 5 provides discharge path, avoid Organic Light Emitting Diode OLED luminous at threshold voltage memory phase.
The pixel-driving circuit that this scheme provides can solve the unevenness of each pixel driving transistors of active matrix organic light-emitting diode T2 threshold voltage effectively, and Organic Light Emitting Diode OLED is along with the working time increases the degeneration that causes cut-in voltage.But this dot structure is comparatively complicated, be unfavorable for the raising of its aperture opening ratio, especially the area that two electric capacity in pixel occupy is larger, has limited to a great extent the miniaturization of pixel, is unfavorable for the further raising of active matrix organic light emitting diode display integrated level.
Summary of the invention
The shortcoming of prior art in view of the above, the object of the present invention is to provide active matrix organic light emitting diode display pixel-driving circuit and driving method thereof, be used for solving prior art active matrix organic light emitting diode display pixel driver device threshold voltage inhomogeneous, and dot structure is complicated, is unfavorable for the problem that its aperture opening ratio improves.
For achieving the above object and other relevant objects, the invention provides active matrix organic light-emitting diode pixel-driving circuit, described circuit comprises: the first transistor, transistor seconds, the 3rd transistor, driving transistors, building-out capacitor and Organic Light Emitting Diode, wherein:
The grid of described the first transistor connects the first scan control signal, and the first electrode is connected with the drain electrode of the 3rd transistorized the second electrode and driving transistors, and the second electrode connects the first end of building-out capacitor and the control grid of driving transistors;
The grid of described transistor seconds connects the second scan control signal, and the second electrode connects second voltage signal, and the first electrode is connected with the source electrode of first utmost point of Organic Light Emitting Diode, the second end of building-out capacitor and driving transistors;
Described the 3rd transistorized grid sending and receiving optical control signal, the first electrode connects the first voltage signal;
Second utmost point of described Organic Light Emitting Diode connects low supply voltage signal.
Preferably, described second voltage signal equates with low supply voltage signal.
Preferably, described the first transistor is symmetrical structure, and its first electrode, the second electrode are interchangeable; Described second, third transistor is symmetrical structure or unsymmetric structure.
Preferably, described the first electrode is drain electrode, and the second electrode is source electrode, and described the first transistor, transistor seconds and the 3rd transistor are N-type, the first anode very of described Organic Light Emitting Diode.
Preferably, described the first electrode is source electrode, and the second electrode is drain electrode, and described the first transistor, transistor seconds and the 3rd transistor are P type, the first negative electrode very of described Organic Light Emitting Diode.
Preferably, described the first transistor, transistor seconds and the 3rd transistor are selected from any one in polycrystalline SiTFT, amorphous silicon film transistor, Zinc oxide based film transistor and OTFT.
Preferably, described driving transistors, except controlling grid, source electrode, drain electrode, also comprises half floating boom, and the doping type of described half floating boom and source electrode, drain contrary; Described half floating boom contacts and forms an embedded type diode with drain doping region; Described control grid extends to drain doping region top and covers its surface, and described half floating boom, drain doping region and the control grid that extends to drain doping region top form an embedded tunneling field-effect transistor.
Correspondingly, the present invention also provides the driving method of above-mentioned active matrix organic light emitting diode display pixel-driving circuit, and the method comprises:
Reseting stage: transistor seconds and the 3rd transistor turns, the first transistor turn-offs, and driving transistors discharges by the 3rd transistor;
Pre-charging stage: the first transistor, transistor seconds and the equal conducting of the 3rd transistor, the first voltage signal charges to building-out capacitor by the first transistor and the 3rd transistor;
Threshold voltage memory phase: the first transistor and transistor seconds conducting, the 3rd transistor turn-offs, building-out capacitor discharges by driving transistors and transistor seconds, and while having discharged, the voltage at described building-out capacitor two ends is the initial threshold voltage of driving transistors;
The charge storage stage: the first transistor turn-offs, transistor seconds and the 3rd transistor turns, second voltage signal acts on the control grid of driving transistors through transistor seconds and building-out capacitor, and by charge storage to half floating boom of driving transistors, the threshold voltage of driving transistors becomes Second Threshold voltage;
Glow phase: the first transistor and transistor seconds turn-off, the 3rd transistor turns, driving transistors drives Organic Light Emitting Diode luminous.
Preferably, at reseting stage, the diode positively biased between half floating boom of driving transistors and drain electrode, discharges to half floating boom of driving transistors by the 3rd transistor.
Preferably, in pre-charging stage, the both end voltage after building-out capacitor charging is higher than the initial threshold voltage of driving transistors.
Preferably, in the charge storage stage, embedded tunneling field-effect transistor conducting in driving transistors, second voltage signal acts on the source electrode of driving transistors through transistor seconds, and through the coupling of building-out capacitor the control grid to driving transistors, charge storage, to half floating boom of driving transistors, is charged to half floating boom of driving transistors, after having charged, the threshold voltage of driving transistors becomes Second Threshold voltage.
Preferably, in glow phase, the initial threshold voltage that the voltage difference at building-out capacitor two ends is driving transistors also remains unchanged, and the luminosity of Organic Light Emitting Diode remains unchanged within the time of a two field picture.
Preferably, in reseting stage, pre-charging stage, threshold voltage memory phase and charge storage stage, the magnitude of voltage of second voltage signal is less than the forward voltage sum of the second pole tension and the Organic Light Emitting Diode of Organic Light Emitting Diode.
As mentioned above, active matrix organic light emitting diode display pixel-driving circuit of the present invention and driving method thereof, have following beneficial effect:
First, in the present invention in active matrix organic light-emitting diode pixel-driving circuit, employing has the driving transistors of an embedded diode/tunneling field-effect transistor, by controlling the control grid of this driving transistors and drain voltage, realize embedded diode/tunneling field-effect transistor and setover, make electric current flow to half floating boom from drain electrode, charge storage in half floating boom of driving transistors, thereby changed the threshold voltage of driving transistors.Because the present invention deposits initial threshold voltage in advance building-out capacitor and is coupled on driving transistors, when Organic Light Emitting Diode is luminous, drive current I
driveonly with threshold voltage variation amount Δ V
threlevant, and it is irrelevant with the initial threshold voltage of driving transistors, thereby avoided the driving transistors initial threshold voltage unevenness of each dot structure in active matrix organic light emitting diode display on the luminous impact bringing of Organic Light Emitting Diode, the homogeneity that shows brightness of image is improved, and active matrix organic light-emitting diode display effect improves.
Secondly, compare with each pixel-driving circuit structure in prior art, in active matrix organic light-emitting diode pixel-driving circuit provided by the invention and driving method, all only adopt the unevenness between each pixel driven transistor threshold voltage of single capacitance compensation, improve the uniformity coefficient that display shows, thereby further improve the display effect of active matrix organic light emitting diode display.Meanwhile, compared with prior art, in active matrix organic light-emitting diode pixel-driving circuit provided by the invention and driving method, only comprise a capacitance structure, with driving transistors, realize simultaneously and driving and signal storage function, reduced electric capacity quantity required in driving circuit, further reduced elemental area, simplify greatly dot structure, be conducive to the raising of its aperture opening ratio simultaneously, can realize the dot structure of high integration.
Accompanying drawing explanation
Fig. 1 is shown as the schematic diagram of the pixel-driving circuit of active organic electroluminescent display in prior art.
Fig. 2 is shown as the schematic diagram of driving sequential of the pixel-driving circuit of active organic electroluminescent display in prior art.
Fig. 3 is shown as the schematic diagram of driving transistors in the present invention.
Fig. 4 is shown as the gate capacitance distribution schematic diagram in driving transistors in the present invention.
Fig. 5 is shown as the schematic diagram of active matrix organic light emitting diode display pixel-driving circuit embodiment 1 in the present invention.
Fig. 6 is shown as the schematic diagram of the driving sequential of active matrix organic light emitting diode display pixel-driving circuit embodiment 1 in the present invention.
Fig. 7 is shown as the schematic diagram of active matrix organic light emitting diode display pixel-driving circuit embodiment 2 in the present invention.
Fig. 8 is shown as the schematic diagram of the driving sequential of active matrix organic light emitting diode display pixel-driving circuit embodiment 2 in the present invention.
Element numbers explanation
V
scan1the first scan control signal
V
scan2the second scan control signal
V
sslow supply voltage signal
V
emslED control signal
V
1the first voltage signal
V
2second voltage signal
T1 the first transistor
T2 transistor seconds
T3 the 3rd transistor
T
drivedriving transistors
C1 building-out capacitor
1 control gate
2 half floating booms
3 source doping region
4 substrates
5 drain doping region
6 tunneling field-effect transistors
7 diffusion regions
8 diodes
9 heavily doped regions
Embodiment
Below, by specific instantiation explanation embodiments of the present invention, those skilled in the art can understand other advantages of the present invention and effect easily by the disclosed content of this instructions.The present invention can also be implemented or be applied by other different embodiment, and the every details in this instructions also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present invention.
In prior art, compensate the unevenness of each pixel drive transistor threshold voltage, the mode that mostly adopts a plurality of electric capacity to combine with transistor, although or electric capacity negligible amounts, but number of transistors is more, cause dot structure complicated, reduce the aperture opening ratio of pixel, affected video picture quality.Pixel-driving circuit of the present invention can not only compensate the unevenness of each pixel drive transistor threshold voltage effectively, and be used in conjunction with thering is the driving transistors of embedded tunneling field-effect pipe and single electric capacity and a small amount of transistor, greatly simplified the structure of pixel.
The present invention has adopted three normal transistor, a driving transistors and a building-out capacitor, wherein, the first transistor and the 3rd transistor synergy control and compensation electric capacity first end discharge and recharge path, the second end that transistor seconds is building-out capacitor provides and discharges and recharges path, and avoid Organic Light Emitting Diode other stages outside glow phase luminous, the 3rd transistor is by the path that discharges and recharges of the first transistor control and compensation electric capacity, and it is luminous by driving transistors, to control Organic Light Emitting Diode, driving transistors is used for driving Organic Light Emitting Diode luminous, the initial threshold voltage of building-out capacitor for preserving driving transistors.
It should be noted that, the diagram providing in the embodiment of the present invention only illustrates basic conception of the present invention in a schematic way, satisfy and only show with assembly relevant in the present invention in graphic but not component count, shape and size drafting while implementing according to reality, during its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
Refer to the schematic diagram of active matrix organic light emitting diode display pixel-driving circuit embodiment 1 in Fig. 5 the present invention.
This active matrix organic light emitting diode display pixel-driving circuit comprises: the first transistor T1, transistor seconds T2, the 3rd transistor T 3, driving transistors T
drive, building-out capacitor C1 and Organic Light Emitting Diode OLED, wherein:
The grid of described the first transistor T1 meets the first scan control signal V
scan1, the second electrode and the driving transistors T of the first electrode and the 3rd transistor T 3
drivedrain electrode be connected, the second electrode meets first end and the driving transistors T of building-out capacitor C1
drivecontrol grid;
The grid of described transistor seconds T2 is connected to OLED OLED, and the second electrode meets second voltage signal V
2, the second end B and the driving transistors T of first utmost point of the first electrode and Organic Light Emitting Diode OLED, building-out capacitor C1
drivesource electrode be connected;
The grid sending and receiving optical control signal V of described the 3rd transistor T 3
ems, the first electrode meets the first voltage signal V
1;
Second utmost point of described Organic Light Emitting Diode OLED meets low supply voltage signal V
ss.Described the first transistor T1 and the 3rd transistor T 3 synergy control and compensation capacitor C 1 first end A discharge and recharge path, the second end B that transistor seconds T2 is building-out capacitor C1 provides and discharges and recharges path, and avoid Organic Light Emitting Diode OLED other stages outside glow phase luminous, the 3rd transistor T 3 is by the path that discharges and recharges of the first transistor T1 control and compensation capacitor C 1, and by driving transistors T
drivecontrol Organic Light Emitting Diode OLED luminous, driving transistors T
drivebe used for driving Organic Light Emitting Diode OLED luminous, described building-out capacitor C1 is used for preserving driving transistors T
driveinitial threshold voltage.
It should be noted that, described the first transistor T1 is symmetrical structure, and its first electrode, the second electrode are interchangeable, in drive circuit works process, can need and current trend according to circuit working, define arbitrarily its first electrode, the second electrode; Described second, third T2/T3 is symmetrical structure or unsymmetric structure, and generally speaking, in drive circuit works process, its first electrode, the second electrode do not change.
In this embodiment, the annexation of each transistor source and drain electrode can be done proper transformation, and for example described the first electrode is drain electrode, and the second electrode is source electrode; Or the first electrode is source electrode, the second electrode is drain electrode.When described the first electrode is drain electrode, when the second electrode is source electrode, described the first transistor T1, transistor seconds T2 and the 3rd transistor T 3 are N-type, the first anode very of described Organic Light Emitting Diode OLED; When described the first electrode is source electrode, the second electrode is when drain electrode, and described the first transistor T1, transistor seconds T2 and the 3rd transistor T 3 are P type, the first negative electrode very of described Organic Light Emitting Diode OLED.
In this embodiment, described the first transistor T1, transistor seconds T2 and the 3rd transistor T 3 are selected from any one in polycrystalline SiTFT, amorphous silicon film transistor, Zinc oxide based film transistor and OTFT.
In this embodiment, described driving transistors T
drivecomprise and controlling outside grid 1, source doping region 3, drain doping region 5, also comprise half floating boom 2, and the doping type of described half floating boom 2 and source doping region 3, drain doping region 5 are contrary; Described half floating boom 2 contacts and forms an embedded type diode with drain doping region 5; Described control grid 1 extends to drain doping region 5 tops and covers its surface, and described half floating boom 2, drain doping region 5 and the control grid 1 that extends to drain doping region 5 tops form an embedded tunneling field-effect transistor.
It should be noted that driving transistors T of the present invention
drivethe change of self threshold voltage can be realized by controlling its grid and drain voltage, by this driving transistors T
drivebe used in conjunction with single building-out capacitor C1, not only compensated each pixel driving transistors T
drivethe unevenness of threshold voltage, and simplified driving circuit.Common MOS transistor take below as comparison other explanation driving transistors T of the present invention
drivethe principle of adjustment and control of threshold voltage:
The electric conductivity of common MOS transistor raceway groove is subject to gate voltage regulation and control, and when grid voltage surpasses threshold voltage, the semiconductor surface under grid will transoid (N-shaped semiconductor variable is p-type semiconductor or contrary), generates conduction electric charge.Gate voltage is larger, and the conduction amount of charge of the accumulation in raceway groove is just more.
Fig. 3 is the schematic diagram of driving transistors of the present invention.
As shown in Figure 3, described driving transistors T
drivecomprise and control grid 1, half floating boom 2, source doping region 3, substrate 4, drain doping region 5.As preferred embodiments, driving transistors T
drivestructure is placed in P type substrate 4 or P type well region, and its source doping region 3, drain doping region 5 are N-type doping, and its half floating boom 2 is the polysilicon structure of P type doping.It is to be noted, half floating boom 2 parts are positioned at raceway groove top and isolate with substrate 4, part contacts with drain doping region 5, and the region contacting with drain doping region 5 at half floating boom 2 forms a more shallow p type diffusion region 7, this p type diffusion region is positioned at the region that drain doping region 5 is surperficial near substrate 4 and contact with half floating boom 2, and half floating boom 2 of this P type doping and p type diffusion region 7 form a PN junction diode 8 with the doped region, building 5 of N-type doping.In addition, control the sidewall that grid 1 covers half floating boom 2 surfaces by gate oxide and is positioned at drain doping region 2 one sides, part extends to drain doping region 5 tops and covers its surface, and half floating boom 2/P type diffusion region 7 of this part and the doping of P type and the N-type heavily doped region 9 that drain doping region 5 is drawn drain electrode form an embedded tunneling field-effect transistor 6.It should be noted that, between part half floating boom 2 and substrate 4, control between grid 1 and half floating boom 2 and substrate 4 and be all arranged at intervals with gate oxide or other similar insulation systems, the conventional techniques that this is well known to those skilled in the art, therefore not to repeat here.
Fig. 4 is gate capacitance distribution schematic diagram in the driving transistors of active matrix organic light-emitting diode pixel-driving circuit in the present invention.
As shown in Figure 4, driving transistors T
drivecan regard as and in the gate capacitance medium of normal transistor, insert an electrode (i.e. half floating boom 2), so just original gate capacitance has been divided into two capacitor C
g1and C
g2series connection.By iunjected charge on half floating boom 2, can change driving transistors T
drivethreshold voltage, regulation and control raceway groove electric conductivity.The principle of its regulation and control threshold voltage can be understood as: driving transistors T
drivethere is initial threshold voltage V
th, as driving transistors T
drivewhile starting working, the electric charge injecting on half floating boom 2 can be by the gate capacitance C between half floating boom 2 and transistor channel
g2in transistor channel one side, induce channel charge, the positive charge on half floating boom 2 is more, and the negative charge of responding in raceway groove is also more, and the electric conductivity of N-type raceway groove is stronger.This effect is equivalent to controlling grid 1, compares before with half floating boom 2 chargings, and 1 need of control grid add less gate voltage and just can in raceway groove, induce the channel charge of equivalent, reach identical conductive effect, so in form driving transistors T
drivethreshold voltage just reduced.
This embodiment also provides an active matrix organic light-emitting diode image element driving method, adopts above-mentioned active matrix organic light-emitting diode pixel-driving circuit to realize.Refer to the schematic diagram of the driving sequential of active matrix organic light emitting diode display pixel-driving circuit embodiment 1 in Fig. 6 the present invention.
It should be noted that, in this embodiment, the first transistor T1, transistor seconds T2 and the 3rd transistor T 3 are N-type, the first electrode of the first transistor T1, transistor seconds T2, the 3rd transistor T 3 is drain electrode, the second electrode is source electrode, the first anode very of Organic Light Emitting Diode OLED, the second negative electrode very.In this embodiment, the negative electrode of Organic Light Emitting Diode OLED connects low supply voltage signal, and preferably, low supply voltage signal is common ground end.
The driving method of described circuit comprises reseting stage, pre-charging stage, threshold voltage memory phase, charge storage stage and glow phase.
It should be noted that, at reseting stage, driving transistors T
drive half floating boom 2 and drain electrode between PN junction diode 8 positively biaseds, by the 3rd transistor T 3, discharge; In pre-charging stage, the both end voltage after building-out capacitor C1 charging is higher than driving transistors T
driveinitial threshold voltage; In the charge storage stage, charge storage is to driving transistors T
drive half floating boom 2 in.Driving transistors T
drivein 6 conductings of embedded tunneling field-effect transistor, second voltage signal V
2through transistor seconds T2, act on driving transistors T
drivesource electrode, and through the coupling of building-out capacitor C1 to driving transistors T
drivecontrol grid 1, by charge storage to driving transistors T
drive half floating boom 2 in, to driving transistors T
drive half floating boom 2 charge, after having charged, driving transistors T
drivethreshold voltage V
thbecome Second Threshold voltage V
th'.
It should be noted that, in reseting stage, pre-charging stage, threshold voltage memory phase and charge storage stage, second voltage signal V
2magnitude of voltage be less than the forward voltage sum of the second pole tension and the Organic Light Emitting Diode OLED of Organic Light Emitting Diode OLED, so that Organic Light Emitting Diode OLED is not luminous in reseting stage, pre-charging stage, threshold voltage memory phase and charge storage stage, and only luminous in glow phase.
Below illustrate the driving method in each stage:
Reseting stage: transistor seconds T2 and the 3rd transistor T 3 conductings, the first transistor T1 turn-offs, driving transistors T
driveby the 3rd transistor T 3, discharge.
In this stage, the second scan control signal V
scan2with LED control signal V
emsbe placed in high level, the first scan control signal V
scan1be placed in low level, transistor seconds T2 and the 3rd transistor T 3 conductings, the first transistor T1 turn-offs, second voltage signal V
2for data input signal, it is a high value, voltage range be 0.5V to 5V, but deficiency is so that Organic Light Emitting Diode OLED is luminous, the first voltage signal V
1be a lower value, voltage range is-arrive-5V of 1V.Second voltage signal V
2by transistor seconds T2, arrive driving transistors T
drivesource electrode, and through the coupling of building-out capacitor C1 to driving transistors T
drivegrid, driving transistors T now
drivegrid voltage be V2, drain voltage is V1, grid voltage is higher than drain voltage, driving transistors T
drivein half floating boom 2 and drain electrode between PN junction positively biased, driving transistors T
drive half floating boom 2 by the 3rd transistor T 3 electric discharges.
Pre-charging stage: the first transistor T1, transistor seconds T2 and the equal conducting of the 3rd transistor T 3, the first voltage signal V
1by the first transistor T1 and 3 couples of building-out capacitor C1 of the 3rd transistor T, charge.
In this stage, the second scan control signal V
scan2with LED control signal V
emsbe still high level, the first scan control signal V
scan1from low level, become high level, the first transistor T1, transistor seconds T2 and the equal conducting of the 3rd transistor T 3, the first voltage signal V
1become a high value, and by the 3rd transistor T 3 and the first transistor T1, be applied to the first end A of building-out capacitor C1, second voltage signal V
2become a lower value, so that the anode level of Organic Light Emitting Diode OLED does not reach the level that makes Organic Light Emitting Diode OLED luminous, second voltage signal V
2through transistor seconds T2, be applied to the second end B of building-out capacitor C1, driving transistors T
drivewhen A, B both end voltage are not also charged to enough large value, in off state, along with the carrying out of charging, A terminal voltage increases, and A, B both end voltage surpass driving transistors T
drivethreshold voltage, driving transistors T
driveconducting, the first end A of building-out capacitor C1 charges by the first transistor T1 and the 3rd transistor T 3, and the voltage at final building-out capacitor C1 two ends is higher than driving transistors T
driveinitial threshold voltage Vth.
Threshold voltage memory phase: the first transistor T1 and transistor seconds T2 conducting, the 3rd transistor T 3 turn-offs, and building-out capacitor C1 is by driving transistors T
drivewith transistor seconds T2 electric discharge, while having discharged, the voltage at described building-out capacitor C1 two ends is driving transistors T
driveinitial threshold voltage.
In this stage, the first scan control signal V
scan1with the second scan control signal V
scan2be still high level, LED control signal V
emsbecome low level, the first transistor T1 and transistor seconds T2 conducting, the 3rd transistor T 3 becomes shutoff from unlatching, the input of V1 no signal, second voltage signal V
2still remain a lower value, the first end A voltage of building-out capacitor C1 is higher than the second end B voltage, driving transistors T
drivestill conducting, building-out capacitor C1 discharges by transistor seconds T2, and the voltage at final building-out capacitor C1 two ends is driving transistors T
driveinitial threshold voltage Vth.
The charge storage stage: the first transistor T1 turn-offs, transistor seconds T2 and the 3rd transistor T 3 conductings, second voltage signal V
2through transistor seconds T2 and building-out capacitor C1, act on driving transistors T
drivecontrol grid 1, and by charge storage to driving transistors T
drive half floating boom 2 in, driving transistors T
drivethreshold voltage vt h become Second Threshold voltage Vth ＇.
In this stage, the first scan control signal V
scan1from high level, become low level, the second scan control signal V
scan2with LED control signal V
emsbe set to high level, the first transistor T1 becomes shutoff from unlatching, transistor seconds T2 and the 3rd transistor T 3 conductings, the first voltage signal V
1revert to original high value, second voltage signal V
2become the data value for showing of actual input, voltage range is arrive-6V of 0V, second voltage signal V
2through transistor seconds T2, arrive driving transistors T
drivesource electrode, i.e. B point, and through the coupling of building-out capacitor C1 to driving transistors T
drivegrid, i.e. A point.Driving transistors T now
drivedrain bias, electronics is from the valence band tunnelling of p raceway groove to conduction band, driving transistors T
drivethe tunneling field-effect transistor of middle embedding is opened, and electric current flows to half floating boom 2 from drain electrode, to driving transistors T
drive half floating boom 2 charge, charge storage is in driving transistors T
drive half floating boom 2 in, the electric current of tunneling field-effect transistor has improved the electromotive force of half floating boom 2, makes driving transistors T
drivethreshold voltage vt h reduce, become Vth ＇, variable quantity is Δ Vth.
Glow phase: the first transistor T1 and transistor seconds T2 turn-off, the 3rd transistor T 3 conductings, driving transistors T
drivedrive Organic Light Emitting Diode OLED luminous.
In this stage, the first scan control signal V
scan1be still low level, the second sweep trace Vscan2 becomes low level from high level, LED control signal V
emsbe still high level, the first transistor T1 and transistor seconds T2 turn-off, the 3rd transistor T 3 conductings, the first voltage signal V
1be still high value, the input of V2 no signal, the voltage difference at building-out capacitor C1 two ends is driving transistors T
driveinitial threshold voltage Vth, and remain unchanged, driving transistors T
drivefor conducting state, drive Organic Light Emitting Diode OLED luminous, driving transistors T
drivebe operated in saturation region, the size of drive current is
Wherein, μ is carrier mobility, and W/L is raceway groove length breadth ratio, and Δ Vth is threshold voltage variation amount, I
drivefor drive current.
In the situation that not considering that raceway groove length breadth ratio W/L and carrier mobility μ affect, drive current I
driveonly with driving transistors T
drivevth is relevant for threshold voltage variation amount Δ, and Vth is constant for threshold voltage variation amount Δ, so driving current constant, and the brightness of Organic Light Emitting Diode OLED remains unchanged within the time of a two field picture.Meanwhile, because drive current is only relevant with threshold voltage variation amount Δ Vth, thereby can compensate the difference between the different pixels driving transistors initial threshold voltage causing due to technological factor.
It should be noted that, in above-mentioned driving method, in glow phase, the first electrode of the first transistor T1 is source electrode, and the second electrode is drain electrode; In other stages, the first electrode of the first transistor is drain electrode, and the second electrode is source electrode.Therefore, the first transistor T1 is symmetrical structure, in the course of the work, its source electrode, drains interchangeablely, does not affect driving circuit overall work.
As optional embodiment, when the first transistor T1, transistor seconds T2 and the 3rd transistor T 3 are P transistor npn npn, drive sequential correspondingly to become the level that is applicable to the conducting of P transistor npn npn or shutoff.
Refer to the schematic diagram of the driving sequential of active matrix organic light emitting diode display pixel-driving circuit embodiment 2 in the schematic diagram of active matrix organic light emitting diode display pixel-driving circuit embodiment 2 in Fig. 7 the present invention and Fig. 8 the present invention.
As different from Example 1, the present embodiment is by the second voltage signal V in embodiment 1
2extremely be connected with second of Organic Light Emitting Diode OLED, in the present embodiment, the second negative electrode very.The first voltage signal V
1both as power supply voltage signal, again as data voltage signal.At reseting stage, the first voltage signal V
1be a lower level, voltage range is-arrive-6V of 1V, by 3 couples of driving transistors T of the 3rd transistor T
drivehalf floating boom 2 discharge; In pre-charging stage, the first voltage signal V
1magnitude of voltage be supply voltage, by the first transistor T1 and 3 pairs of A points of the 3rd transistor T, charge; In the charge storage stage, the first voltage signal V
1level be data voltage V2, with the data voltage V2 that shows information, through the 3rd transistor T 3, arrive driving transistors T
drivedrain terminal, the voltage range of V2 is that 1V is to 6V.Meanwhile, the negative electrode of Organic Light Emitting Diode OLED becomes low supply voltage signal V
ss, voltage range is arrive-6V of 0V, is coupled to the grid of driving tube through the effect of capacitor C 1, final driving transistors T
drivethe tunneling field-effect transistor of middle embedding is opened, to driving transistors T
drivehalf floating boom 2 charge; In glow phase, voltage signal line V
1level revert to again supply voltage.
Although compare the first voltage signal V in embodiment 2 with embodiment 1
1with second voltage signal V
2voltage change to some extent, but the effect that embodiment 2 reached in each driving stage is substantially the same manner as Example 1.The part that embodiment 2 and embodiment 1 repeat please refer to the explanation of embodiment 1, does not repeat them here.
In sum, active matrix organic light emitting diode display pixel-driving circuit of the present invention and driving method thereof, have following beneficial effect:
First, in the present invention in active matrix organic light-emitting diode pixel-driving circuit, employing has the driving transistors of an embedded diode/tunneling field-effect transistor, by controlling the control grid of this driving transistors and drain voltage, realize embedded diode/tunneling field-effect transistor and setover, make electric current flow to half floating boom from drain electrode, charge storage in half floating boom of driving transistors, thereby changed the threshold voltage of driving transistors.Because the present invention deposits initial threshold voltage in advance building-out capacitor and is coupled on driving transistors, when Organic Light Emitting Diode is luminous, drive current I
driveonly with threshold voltage variation amount Δ V
threlevant, and it is irrelevant with the initial threshold voltage of driving transistors, thereby avoided the driving transistors initial threshold voltage unevenness of each dot structure in active matrix organic light emitting diode display on the luminous impact bringing of Organic Light Emitting Diode, the homogeneity that shows brightness of image is improved, and active matrix organic light-emitting diode display effect improves.
Secondly, compare with each pixel-driving circuit structure in prior art, in active matrix organic light-emitting diode pixel-driving circuit provided by the invention and driving method, all only adopt the unevenness between each pixel driven transistor threshold voltage of single capacitance compensation, improve the uniformity coefficient that display shows, thereby further improve the display effect of active matrix organic light emitting diode display.Meanwhile, compared with prior art, in active matrix organic light-emitting diode pixel-driving circuit provided by the invention and driving method, only comprise a capacitance structure, with driving transistors, realize simultaneously and driving and signal storage function, reduced electric capacity quantity required in driving circuit, further reduced elemental area, simplify greatly dot structure, be conducive to the raising of its aperture opening ratio simultaneously, can realize the dot structure of high integration.So the present invention has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all can, under spirit of the present invention and category, modify or change above-described embodiment.Therefore, such as in affiliated technical field, have and conventionally know that the knowledgeable, not departing from all equivalence modifications that complete under disclosed spirit and technological thought or changing, must be contained by claim of the present invention.
Claims (12)
1. an active matrix organic light-emitting diode pixel-driving circuit, is characterized in that, described circuit comprises: the first transistor, transistor seconds, the 3rd transistor, driving transistors, building-out capacitor and Organic Light Emitting Diode, wherein:
The grid of described the first transistor connects the first scan control signal, and the first electrode is connected with the drain electrode of the 3rd transistorized the second electrode and driving transistors, and the second electrode connects the first end of building-out capacitor and the control grid of driving transistors;
The grid of described transistor seconds connects the second scan control signal, and the second electrode connects second voltage signal, and the first electrode is connected with the source electrode of first utmost point of Organic Light Emitting Diode, the second end of building-out capacitor and driving transistors;
Described the 3rd transistorized grid sending and receiving optical control signal, the first electrode connects the first voltage signal;
Second utmost point of described Organic Light Emitting Diode connects low supply voltage signal.
2. active matrix organic light-emitting diode pixel-driving circuit according to claim 1, is characterized in that: described second voltage signal equates with low supply voltage signal.
3. active matrix organic light-emitting diode pixel-driving circuit according to claim 1 and 2, it is characterized in that: described driving transistors is except controlling grid, source electrode, drain electrode, also comprise half floating boom, and the doping type of described half floating boom and source electrode, drain electrode are contrary; Described half floating boom contacts and forms an embedded type diode with drain doping region; Described control grid extends to drain doping region top and covers its surface, and described half floating boom, drain doping region and the control grid that extends to drain doping region top form an embedded tunneling field-effect transistor.
4. active matrix organic light-emitting diode pixel-driving circuit according to claim 1 and 2, is characterized in that: described the first transistor is symmetrical structure, and its first electrode, the second electrode are interchangeable; Described second, third transistor is symmetrical structure or unsymmetric structure.
5. active matrix organic light-emitting diode pixel-driving circuit according to claim 4, it is characterized in that: described the first electrode is drain electrode, the second electrode is source electrode, described the first transistor, transistor seconds and the 3rd transistor are N-type, the first anode very of described Organic Light Emitting Diode.
6. active matrix organic light-emitting diode pixel-driving circuit according to claim 4, it is characterized in that: described the first electrode is source electrode, the second electrode is drain electrode, described the first transistor, transistor seconds and the 3rd transistor are P type, the first negative electrode very of described Organic Light Emitting Diode.
7. an active matrix organic light emitting diode display image element driving method, adopts the active matrix organic light-emitting diode pixel-driving circuit described in any one in claim 1～6, it is characterized in that, the method comprises:
Reseting stage: transistor seconds and the 3rd transistor turns, the first transistor turn-offs, and driving transistors discharges by the 3rd transistor;
Pre-charging stage: the first transistor, transistor seconds and the equal conducting of the 3rd transistor, the first voltage signal charges to building-out capacitor by the first transistor and the 3rd transistor;
Threshold voltage memory phase: the first transistor and transistor seconds conducting, the 3rd transistor turn-offs, building-out capacitor discharges by driving transistors and transistor seconds, and while having discharged, the voltage at described building-out capacitor two ends is the initial threshold voltage of driving transistors;
The charge storage stage: the first transistor turn-offs, transistor seconds and the 3rd transistor turns, second voltage signal acts on the control grid of driving transistors through transistor seconds and building-out capacitor, and by charge storage to half floating boom of driving transistors, the threshold voltage of driving transistors becomes Second Threshold voltage;
Glow phase: the first transistor and transistor seconds turn-off, the 3rd transistor turns, driving transistors drives Organic Light Emitting Diode luminous.
8. active matrix organic light-emitting diode pixel-driving circuit driving method according to claim 7, it is characterized in that: at reseting stage, diode positively biased between half floating boom of driving transistors and drain electrode, discharges to half floating boom of driving transistors by the 3rd transistor.
9. active matrix organic light-emitting diode pixel-driving circuit driving method according to claim 7, is characterized in that: in pre-charging stage, the both end voltage after building-out capacitor charging is higher than the initial threshold voltage of driving transistors.
10. active matrix organic light-emitting diode pixel-driving circuit driving method according to claim 7, it is characterized in that: in the charge storage stage, embedded tunneling field-effect transistor conducting in driving transistors, second voltage signal acts on the source electrode of driving transistors through transistor seconds, and through the coupling of building-out capacitor the control grid to driving transistors, by charge storage to half floating boom of driving transistors, half floating boom to driving transistors charges, after having charged, the threshold voltage of driving transistors becomes Second Threshold voltage.
11. active matrix organic light-emitting diode image element driving methods according to claim 7, it is characterized in that: in glow phase, the voltage difference at building-out capacitor two ends is the initial threshold voltage of driving transistors and remains unchanged, and the luminosity of Organic Light Emitting Diode remains unchanged within the time of a two field picture.
12. active matrix organic light-emitting diode pixel-driving circuit driving methods according to claim 7, it is characterized in that: in reseting stage, pre-charging stage, threshold voltage memory phase and charge storage stage, the magnitude of voltage of second voltage signal is less than the forward voltage sum of the second pole tension and the Organic Light Emitting Diode of Organic Light Emitting Diode.
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