CN103680408A - AMOLED pixel drive circuit, drive method and array drive system - Google Patents

Abstract

The invention provides an AMOLED pixel drive circuit, a drive method and an array drive system. The AMOLED pixel drive circuit comprises a first transistor, a second transistor, an organic light emitting diode and a drive transistor, wherein a threshold voltage of the drive transistor can be adjusted. The grid of the first transistor is connected with a first scanning signal, the first electrode of the first transistor is connected with a data signal, and the second electrode of the first transistor is connected with a control grid of the drive transistor. A source doped region of the drive transistor is connected to the ground, and a drain doped region of the drive resistor is connected with the first pole of the organic light emitting diode. The second pole of the organic light emitting diode is connected with an external power source. The grid of the second transistor is connected with a second scanning signal, and the first electrode and the second electrode of the second transistor are connected with the first pole and the second pole of the organic light emitting diode respectively. According to the AMOLED pixel drive circuit, a traditional capacitor and a PMOS transistor are replaced by the drive transistor with the adjustable threshold voltage. Therefore, the relative aperture of the pixel drive circuit is greatly improved, and light-emitting efficiency of the pixel drive circuit is greatly improved.

Description

AMOLED pixel-driving circuit, driving method and array drive system

Technical field

The present invention relates to the pixel driver technology of OLED display, particularly relate to a kind of AMOLED pixel-driving circuit, driving method and array drive system.

Background technology

Active matrix organic light-emitting diode (AMOLED), passive drive Organic Light Emitting Diode (PMOLED) than traditional, has the response time fast, and contrast is high, the advantages such as visible angle is large, have become the strong rival in display technique of future generation field in recent years.

The most basic light emitting pixel structure of AMOLED is 2T1C structure, and it is comprised of switching transistor T1, driving transistors T2, capacitor C 1 and Organic Light Emitting Diode D1, as shown in Figure 1.The grid of described switching transistor T1 connects sweep signal Vscan, drain electrode connection data signal Vdata, and source electrode connects the grid of driving transistors T2 and first utmost point of described capacitor C 1; The source electrode of described driving transistors T2 connects second utmost point of described capacitor C 1 and is connected with external power source VDD, and drain electrode connects first utmost point of described Organic Light Emitting Diode D1, the second utmost point ground connection of described Organic Light Emitting Diode D1.This structure has maximum relative aperture, and in sub-pixel, the ratio of light-emitting area and pixel entire area is maximum, like this can be so that the luminescence efficiency of pixel is the highest.

In the pixel of above-mentioned 2T1C structure, the luminosity of pixel is determined by outside digital signal, after digital analog converter, form by voltage is input on data-signal Vdata, when opening switching transistor T1, signal storage is in capacitor C 1, and driving transistors T2 has fixing gate source voltage when pixel is luminous like this, flow through like this driving transistors T2 and Organic Light Emitting Diode electric current also just invariable, the luminous intensity of Organic Light Emitting Diode is maintained.Pixel can be launched according to different data-signal Vdata the light of different brightness thus.For the pixel of above-mentioned 2T1C structure, its driving transistors pipe T2 generally adopts PMOS transistor, and therefore the data-signal Vdata of input is lower, and the electric current that flows through Organic Light Emitting Diode D1 is larger, and brightness is just larger.

In general, have the index of a relative aperture in AMOLED pixel, it is defined as light-emitting area in pixel and, than the area of upper pixel, is commonly used to characterize the luminescence efficiency of display.And in a pixel, owing to need to considering the electric leakage situation of electric capacity, general capacitor C 1 will account for a big chunk area of pixel, normally three of driving transistors T2 times, and the area of switching transistor T1 is minimum, so in AMOLED pixel, whether exist electric capacity can become the key factor of restriction pixel luminescence efficiency.Because the capacity area of traditional 2T1C dot structure is 3 times of left and right of driving transistors T2 area, therefore, the relative aperture of traditional 2T1C dot structure is:

$\mathrm{aperture\; ratlo}=\frac{A_D}{A_D+A_{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">T</figure-callout>}1}+A_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">T</figure-callout>}2}+{\mathrm{<figure-callout\; id="1"\; label="A\; C"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">A</figure-callout>}}_C}\&ap;\frac{A_D}{A_D+A_{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">T</figure-callout>}1}+{4\mathrm{<figure-callout\; id="2"\; label="A\; T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">A</figure-callout>}}_T}$

Wherein, A _dfor the area of Organic Light Emitting Diode, A _t1for the area of switching transistor, A _t2for the area of driving transistors, A _c1for the area of electric capacity, visible, the relative aperture of traditional 2T1C pixel-driving circuit is less, has a strong impact on the raising of luminescence efficiency.

As mentioned above, how to realize a kind of novel dot structure that can eliminate the electric capacity in AMOLED pixel and become one of emphasis of current research.

Summary of the invention

The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of AMOLED pixel-driving circuit, driving circuit and driving method, for solving the existence due to electric capacity in prior art AMOLED driving circuit, make the problems such as its relative aperture is little, and luminescence efficiency is low.

For achieving the above object and other relevant objects, the invention provides an AMOLED pixel-driving circuit, described pixel-driving circuit comprises: the first transistor, transistor seconds, Organic Light Emitting Diode and driving transistors, described driving transistors comprises control gate and half floating boom, and its threshold voltage is adjustable; The grid of described the first transistor connects the first sweep signal, the first electrode connection data signal, and the second electrode connects the control gate of described driving transistors; The source ground of described driving transistors, drain electrode connects first utmost point of described Organic Light Emitting Diode; Second utmost point of described Organic Light Emitting Diode connects external power source; The grid of described transistor seconds connects the second sweep signal, and the first electrode and the second electrode connect respectively first utmost point and second utmost point of described Organic Light Emitting Diode.

A kind of preferred version as AMOLED pixel-driving circuit of the present invention, described driving transistors comprises control gate, half floating boom, drain doping region and source doping region, wherein: described half floating boom be take covering described driving transistors channel region and the part drain doping region surface that gate dielectric layer is interval, and described half floating boom partly extends to described drain doping region surface contact with it; In described drain doping region, also comprise that one is positioned at described half floating boom below and the diffusion region of contact with it, and one and spaced drain contact region, this diffusion region; The doping type of described half floating boom and described diffusion region is contrary with the doping type of drain doping region, source doping region and drain contact region, and described half floating boom and described diffusion region and drain doping region form a pn junction diode; Described control gate be take the surface that is covered in described half floating boom, sidewall and the part drain doping region surface that gate dielectric layer is interval, on described control gate, during making alive, between described drain contact region and half floating boom, forms a tunnel-through diode.

Further, by institute's making alive on the drain electrode of described driving transistors and control gate, control the quantity of electric charge of described half floating boom storage, adjustable to realize the threshold voltage of described driving transistors.

Further, the threshold voltage of described driving transistors is adjusted by following process:

Charging process: the control gate of described driving transistors adds negative voltage, drain electrode adds positive voltage, and electric charge, because tunneling effect enters half floating boom, reduces the threshold voltage of described driving transistors;

Discharge process: the control gate institute making alive of described driving transistors is greater than described drain electrode institute making alive, described pn junction diode positively biased, the electric charge in described half floating boom discharges by described pn junction diode, and the threshold voltage of described driving transistors improves.

As a kind of preferred version of AMOLED pixel-driving circuit of the present invention, described the first transistor and transistor seconds are any one in polycrystalline SiTFT, amorphous silicon film transistor, Zinc oxide based film transistor and OTFT.

The present invention also provides a kind of driving method of the AMOLED pixel-driving circuit as described in above-mentioned any one scheme, comprising:

Programming phases: described the first transistor and transistor seconds conducting, described data-signal is programmed to the threshold voltage of described driving transistors;

Glow phase: described the first transistor conducting, transistor seconds turn-offs, and described data-signal is inputted the first voltage V ₁, that is: the control gate of described driving transistors is inputted the first voltage V ₁make described Organic Light Emitting Diode luminous.

A kind of preferred version as the driving method of AMOLED pixel-driving circuit of the present invention, also comprises before described programming phases:

Initial phase: the first transistor and transistor seconds conducting, described data-signal input second voltage V ₁, that is: the control gate of described driving transistors is inputted second voltage V ₂, external power source input tertiary voltage V ₃, and V ₃<V ₂, make the pn junction diode positively biased in described driving transistors, the electric charge storing to empty described driving transistors half floating boom.

As a kind of preferred version of the driving method of AMOLED pixel-driving circuit of the present invention, in programming phases, the threshold voltage of described driving transistors is changed into:

V _th＝V _th0+ΔV _th

V in formula _thfor the threshold voltage after described driving transistors programming, V _th0initial threshold voltage while emptying electric charge for this driving transistors half floating boom, Δ V _thfor the variable quantity after this drive transistor threshold voltage programming;

In glow phase, the electric current that described Organic Light Emitting Diode flows through is:

$I=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}(V_1-V_{\mathrm{th}})=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}{(V_1-V_{\mathrm{th}0}-{\mathrm{\&Delta;V}}_{\mathrm{th}})}^2$

In formula, I is the electric current that flows through Organic Light Emitting Diode and driving transistors, and μ is carrier mobility, C _oxfor unit area gate oxide electric capacity, W is driving transistors grid width, and L is that driving transistors grid are long.

A kind of preferred version as the driving method of AMOLED pixel-driving circuit of the present invention, in programming phases, the control gate of described driving transistors adds negative voltage, and drain electrode adds positive voltage, and electric charge reduces the threshold voltage of described driving transistors because tunneling effect enters half floating boom.

The present invention also provides a kind of AMOLED pel array drive system, comprising:

Data-signal driving circuit, for generation of data-signal;

Sweep circuit, for generation of the first sweep signal and the second sweep signal;

Pel array, by a plurality of AMOLED pixel-driving circuits as described in above-mentioned any one scheme, being matrix arrangement forms, wherein, described a plurality of pixel-driving circuit shares same external power source and ground wire, pixel-driving circuit in each row shares described the first sweep signal and the second sweep signal, the pixel-driving circuit shared data signal in each row.

As mentioned above, the invention provides a kind of AMOLED pixel-driving circuit, driving method and array drive system, described pixel-driving circuit comprises: the first transistor, transistor seconds, Organic Light Emitting Diode and driving transistors, and the threshold voltage of described driving transistors is adjustable; The grid of described the first transistor connects the first sweep signal, the first electrode connection data signal, and the second electrode connects the control gate of described driving transistors; The source doping region ground connection of described driving transistors, drain doping region connects first utmost point of described Organic Light Emitting Diode; Second utmost point of described Organic Light Emitting Diode connects external power source; The grid of described transistor seconds connects the second sweep signal, and the first electrode and the second electrode connect respectively first utmost point and second utmost point of described Organic Light Emitting Diode.The present invention adopts an adjustable driving transistors of threshold value to replace traditional electric capacity and PMOS transistor, has improved widely the relative aperture of pixel-driving circuit, thereby has improved widely the luminescence efficiency of pixel-driving circuit.Driving method of the present invention is simple, and luminescence efficiency is high, can be widely used in the fields such as flat pannel display.

Accompanying drawing explanation

Fig. 1 is shown as the electrical block diagram of 2T1C dot structure of the prior art.

Fig. 2 is shown as the electrical block diagram of AMOLED pixel-driving circuit of the present invention.

Fig. 3 is shown as the structural representation of the driving transistors that AMOLED pixel-driving circuit of the present invention adopts.

Fig. 4 is shown as the schematic equivalent circuit of the driving transistors that AMOLED pixel-driving circuit of the present invention adopts.

Fig. 5 is shown as the electrical block diagram of AMOLED pel array drive system of the present invention.

Fig. 6～Fig. 7 is shown as the driving method sequential configuration schematic diagram of AMOLED pel array drive system of the present invention.

Element numbers explanation

Vsc1 the first sweep signal

Vsc2 the second sweep signal

Vd data-signal

T1 the first transistor

T2 transistor seconds

T3 driving transistors

D1 Organic Light Emitting Diode

101 Semiconductor substrate

102 source doping region

103 drain doping region

104 drain contact region

105 diffusion regions

106 gate dielectric layers

107 half floating booms

108 control gates

109 tunnel-through diodes

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.

Refer to Fig. 2～Fig. 7.It should be noted that, the diagram providing in the present embodiment 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.

Embodiment 1

As shown in Figure 2 to 4, the present embodiment provides an AMOLED pixel-driving circuit, and described pixel-driving circuit comprises:

The first transistor T1, transistor seconds T2, Organic Light Emitting Diode D1 and driving transistors T3, described driving transistors T3 comprises control gate and half floating boom, and its threshold voltage is adjustable;

The grid of described the first transistor T1 connects the first sweep signal Vsc1, the first electrode connection data signal Vd, and the second electrode connects the control gate of described driving transistors T3; The source doping region ground connection of described driving transistors T3, drain doping region connects first utmost point of described Organic Light Emitting Diode D1; Second utmost point of described Organic Light Emitting Diode D1 connects external power source ELVDD; The grid of described transistor seconds T2 connects the second sweep signal Vsc2, and the first electrode and the second electrode connect respectively first utmost point and second utmost point of described Organic Light Emitting Diode D1.

It should be noted that, in the present embodiment, described the first transistor T1 and transistor seconds T2 are N-type transistor, certainly, in other embodiments, described the first transistor T1 and transistor seconds T2 can be also P transistor npn npn, can select suitable electrode connection mode according to these two transistorized doping types, do not limit the scope of application of the present invention.

Particularly, the first electrode of described the first transistor T1 is drain electrode, the second electrode is source electrode, the first electrode of described transistor seconds T2 for drain electrode and be connected with the negative electrode of described Organic Light Emitting Diode D1, second very source electrode and while be connected with external power source with the anode of described Organic Light Emitting Diode D1.It should be noted that, the first transistor T1, transistor seconds T2 are switching tube, its first electrode, the second electrode are interchangeable, as optional embodiment, the first electrode of the first transistor T1 and transistor seconds T2 is source electrode, the second electrode is drain electrode, does not affect the implementation result of the present embodiment.

As shown in Figure 3, in the present embodiment, described driving transistors comprises Semiconductor substrate 101, control gate 108, half floating boom 107, drain doping region 103 and source doping region 102, wherein:

Described half floating boom 107 take that gate dielectric layer 106 is interval is covered in described driving transistors channel region and part drain doping region 103 surfaces, and described half floating boom 107 parts extend to described drain doping region 103 tops contact with it;

In described drain doping region 103, also comprise that one is positioned at described half floating boom 107 belows and the diffusion region 105 of contact with it, and one and spaced drain contact region 104, this diffusion region 105;

The doping type of described half floating boom 107 and described diffusion region 105 is contrary with the doping type of drain doping region 103, source doping region 102 and drain contact region 104, and described half floating boom 107 and described diffusion region 105 form a pn junction diode with drain doping region 103;

Described control gate 108 be take the surface that is covered in described half floating boom 107, sidewall and part drain doping region 103 surfaces that gate dielectric layer 106 is interval, when described control gate 108 adds voltage, between described drain contact region 104 and half floating boom, form a tunnel-through diode 109.

For the principle of work of the driving transistors T3 that the present invention adopts is described better, take half floating boom of common MOS transistor driving transistors T3 of the present invention as comparison other the illustrates principle of adjustment and control to transistor threshold voltage below.

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 structural representation of driving transistors T3, driving transistors T3 mainly comprises Semiconductor substrate 101, control gate 108, half floating boom 107, drain doping region 103 and source doping region 102, wherein, half floating boom 107 of p-type doping, between the drain doping region 103 of the diffusion region 105 of p-type doping and N-shaped doping, form pn junction diode, described control gate 108 is covered in the surface of described half floating boom 107, sidewall and part drain doping region 103 surfaces, cover the drain doping region between 105Ji drain contact region, described diffusion region 104, while applying a negative voltage on described control gate 108, can cause the band curvature in region between 105He drain contact region 104, described diffusion region, form a tunnel-through diode 109.In addition, driving transistors T3 can regard as and in the gate capacitance medium of normal transistor, inserted an electrode, as shown in Figure 4, so just original gate capacitance has been divided into the series connection of two gate capacitance C1 and C2.By iunjected charge on half floating boom 107, can change the threshold voltage of driving transistors, the electric conductivity of regulation and control raceway groove.The principle of driving transistors T3 regulation and control threshold voltage can be understood as: the electric charge injecting on half floating boom 107 can induce channel charge in driving transistors raceway groove one side by the gate capacitance C2 between half floating boom 107 and transistor channel, positive charge on half floating boom 107 is more, the negative charge of responding in raceway groove is also more, and the electric conductivity of N-type raceway groove is stronger.This effect equivalence is to control gate 108, compare before with half floating boom 107 chargings, 108 need of control gate add less gate voltage just can induce the channel charge of equivalent in raceway groove, reaches identical conductive effect, and the threshold voltage of driving transistors T3 has just reduced so in form.

Visible, for the driving transistors T3 in the present embodiment, by institute's making alive on described drain doping region 103 and described control gate 108, control the quantity of electric charge of described half floating boom 107 storages, the threshold voltage that just can realize described driving transistors T3 is adjustable.

Further, the threshold voltage of described driving transistors T3 is adjusted by following process:

Charging process: the control gate 108 of described driving transistors T3 adds negative voltage, drain electrode 103 adds positive voltage, and electric charge, because tunneling effect enters half floating boom 107, reduces the threshold voltage of described driving transistors T3;

Discharge process: 108 making alives of control gate of described driving transistors T3 are greater than 103 making alives of described drain electrode, described tunnel-through diode positively biased, electric charge in described half floating boom 107 discharges by described pn junction diode, and the threshold voltage of described driving transistors T3 improves.

As example, described the first transistor T1 and transistor seconds T2 are any one in polycrystalline SiTFT, amorphous silicon film transistor, Zinc oxide based film transistor and OTFT.

AMOLED pixel-driving circuit of the present invention has huge advantage than traditional 2T1C pixel-driving circuit, and the relative aperture of 3T type AMOLED pixel-driving circuit of the present invention is:

$\mathrm{aperture\; ratlo}=\frac{A_D}{A_D+{2A}_{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">T</figure-callout>}1}+A_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA0000441844260000031.png,HDA0000441844260000041.png"\; state="\{\{state\}\}">T</figure-callout>}2}}$

Wherein, the area of Organic Light Emitting Diode D1 is A _d, the area of the first transistor T1 and transistor seconds T2 is A _t1, driving transistors T3 area be A _t2, clearly, the relative aperture of 3T type AMOLED pixel-driving circuit of the present invention is larger than traditional 2T1C pixel-driving circuit, and luminescence efficiency is higher.

The present embodiment also provides a kind of driving method of AMOLED pixel-driving circuit, still take the first transistor T1, transistor seconds T2 to be N-type transistor as example, and this driving method comprises:

Programming phases: the first sweep signal Vsc1 and the second sweep signal Vsc2 input high level, described the first transistor T1 and transistor seconds T2 conducting, described data-signal Vd programmes to the threshold voltage of described driving transistors T3, after programming phases, the threshold voltage of described driving transistors T3 is changed into:

V _th＝V _th0+ΔV _th

V in formula _thfor the threshold voltage after described driving transistors T3 programming, V _th0initial threshold voltage while emptying electric charge for this driving transistors T3 half floating boom 107, Δ V _thfor the variable quantity after the programming of this driving transistors T3 threshold voltage;

Glow phase: the first sweep signal Vsc1 input high level makes the first transistor T1 conducting, the second sweep signal Vsc2 input low level turn-offs transistor seconds T2, and now, data-signal Vd inputs the first voltage V ₁, that is: the control gate 108 of described driving transistors T3 is inputted the first voltage V ₁, make described Organic Light Emitting Diode D1 luminous, in glow phase, the electric current that described Organic Light Emitting Diode D1 flows through is:

$I=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}(V_1-V_{\mathrm{th}})=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}{(V_1-V_{\mathrm{th}0}-{\mathrm{\&Delta;V}}_{\mathrm{th}})}^2$

In formula, I is the electric current that flows through Organic Light Emitting Diode and driving transistors, and μ is carrier mobility, C _oxfor unit area gate oxide electric capacity, W is driving transistors grid width, and L is that driving transistors grid are long.

Particularly, in programming phases, the control gate 108 of described driving transistors T3 adds negative voltage, and drain electrode 103 adds positive voltage, and electric charge reduces the threshold voltage of described driving transistors T3 because tunneling effect enters half floating boom 107.It should be noted that, the programming phases data-signal Vd luminosity required to respective pixel is relevant, and choosing of the concrete magnitude of voltage of data-signal Vd is corresponding with shade of gray, specifically chooses and computing method are well known to those skilled in the art, and therefore not to repeat here.

In addition, in order further to increase the precision of programming phases, before described programming phases, also increased initial phase, in initial phase, the first sweep signal Vsc1 and the second sweep signal Vsc2 input high level make the first transistor T1 and transistor seconds T2 conducting, data-signal Vd input second voltage V ₂, that is: the control gate 108 of described driving transistors T3 is inputted second voltage V ₂, external power source ELVDD input tertiary voltage V ₃, and V ₃<V ₂, make the pn junction diode positively biased in described driving transistors T3, the electric charge storing to empty described driving transistors T3 half floating boom 107.Before programming phases, increase initial phase, can control more accurately the threshold voltage of described driving transistors T3, increase the precision of programming phases.In order to simplify sequential configuration, in the present embodiment, described second voltage V ₂with described the first voltage V ₁equate.

Embodiment 2

As shown in Figure 5, the present embodiment provides a kind of driving circuit of AMOLED pixel-driving circuit, comprising:

Data-signal driving circuit, for generation of data-signal Vd;

Sweep circuit, for generation of the first sweep signal Vsc1 and the second sweep signal Vsc2;

Pel array, by a plurality of AMOLED pixel-driving circuits, being matrix arrangement forms, the concrete structure of described AMOLED pixel-driving circuit as described in Example 1, wherein, described a plurality of pixel-driving circuit shares same external power source and ground wire, pixel-driving circuit in each row shares described the first sweep signal Vsc1 and the second sweep signal Vsc2, the pixel-driving circuit shared data signal Vd in each row.

As shown in Figure 6, the present embodiment also provides a kind of driving method of driving circuit of AMOLED pixel-driving circuit, still take the first transistor T1, transistor seconds T2 to be N-type transistor as example, and described driving method comprises:

Programming phases: the first sweep signal Vsc1 in corresponding row and the second sweep signal Vsc2 input high level make the first transistor T1 and the transistor seconds T2 conducting of corresponding row, described data-signal Vd programmes to the threshold voltage of the driving transistors T3 of this row pixel-driving circuit successively, after programming finishes, the threshold voltage of each driving transistors T3 is changed into:

V _th(i,j)＝V _th0+ΔV _th(i,j)

V in formula _{th (i, j)}be the threshold voltage after the driving transistors T3 programming of pixel-driving circuit of the capable j of i row, V _th0initial threshold voltage while emptying electric charge for this driving transistors T3 half floating boom 107, Δ V _thfor the variable quantity after the programming of this driving transistors T3 threshold voltage;

Glow phase: the first sweep signal Vsc1 input high level of all pixel-driving circuits makes the first transistor conducting, the second sweep signal Vsc2 input low level turn-offs transistor seconds, and data-signal Vd inputs the first voltage V ₁, that is: the control gate 108 of driving transistors T3 is inputted the first voltage V ₁, the electric current that the Organic Light Emitting Diode D1 (i, j) of different pixels driving circuit flows through is:

$I_{(i,j)}=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}(V_1-V_{\mathrm{th}(i,j)})=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}{(V_1-V_{\mathrm{th}0}-{\mathrm{\&Delta;V}}_{\mathrm{th}(i,j)})}^2$

I in formula _{(I, j)}for flowing through corresponding Organic Light Emitting Diode and the electric current of driving transistors, μ is carrier mobility, C _oxfor unit area gate oxide electric capacity, W is driving transistors grid width, and L is that driving transistors grid are long.

In addition, in order further to increase the precision of programming phases, before described programming phases, also increased initial phase, as shown in Figure 7, in initial phase, the first sweep signal Vsc1 of all pixel-driving circuits and the second sweep signal Vsc2 input high level, the first transistor T1 and transistor seconds T2 conducting, data-signal Vd input second voltage V ₂, that is: the control gate 108 of driving transistors T3 is inputted second voltage V ₂, external power source input tertiary voltage V ₃, and V ₃<V ₂, make the pn junction diode positively biased in each pixel-driving circuit driving transistors T3, the electric charge storing to empty each driving transistors T3 half floating boom 107.Before programming phases, increase initial phase, can control more accurately the threshold voltage of described driving transistors T3, increase the precision of programming phases.In order to simplify sequential configuration, in the present embodiment, described second voltage V ₂with described the first voltage V ₁equate.

As mentioned above, the invention provides an AMOLED pixel-driving circuit, driving method and array drive system, described pixel-driving circuit comprises: the first transistor, transistor seconds, Organic Light Emitting Diode and driving transistors, and the threshold voltage of described driving transistors is adjustable; The grid of described the first transistor connects the first sweep signal, the first electrode connection data signal, and the second electrode connects the control gate of described driving transistors; The source doping region ground connection of described driving transistors, drain doping region connects first utmost point of described Organic Light Emitting Diode; Second utmost point of described Organic Light Emitting Diode connects external power source; The grid of described transistor seconds connects the second sweep signal, and the first electrode and the second electrode connect respectively first utmost point and second utmost point of described Organic Light Emitting Diode.The present invention adopts an adjustable driving transistors of threshold value to replace traditional electric capacity and PMOS transistor, has improved widely the relative aperture of pixel-driving circuit, thereby has improved widely the luminescence efficiency of pixel-driving circuit.Driving method of the present invention is simple, and luminescence efficiency is high, can be widely used in the fields such as flat pannel display.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 (10)

1. an AMOLED pixel-driving circuit, is characterized in that, described pixel-driving circuit comprises:

The first transistor, transistor seconds, Organic Light Emitting Diode and driving transistors, described driving transistors comprises control gate and half floating boom, and its threshold voltage is adjustable;

The grid of described the first transistor connects the first sweep signal, the first electrode connection data signal, and the second electrode connects the control gate of described driving transistors; The source ground of described driving transistors, drain electrode connects first utmost point of described Organic Light Emitting Diode; Second utmost point of described Organic Light Emitting Diode connects external power source; The grid of described transistor seconds connects the second sweep signal, and the first electrode and the second electrode connect respectively first utmost point and second utmost point of described Organic Light Emitting Diode.

2. AMOLED pixel-driving circuit according to claim 1, is characterized in that: described driving transistors comprises control gate, half floating boom, drain doping region and source doping region, wherein:

Described half floating boom be take covering described driving transistors channel region and the part drain doping region surface that gate dielectric layer is interval, and described half floating boom partly extends to described drain doping region surface contact with it;

In described drain doping region, also comprise that one is positioned at described half floating boom below and the diffusion region of contact with it, and one and spaced drain contact region, this diffusion region;

The doping type of described half floating boom and described diffusion region is contrary with the doping type of drain doping region, source doping region and drain contact region, and described half floating boom and described diffusion region and drain doping region form a pn junction diode;

Described control gate be take the surface that is covered in described half floating boom, sidewall and the part drain doping region surface that gate dielectric layer is interval, on described control gate, during making alive, between described drain contact region and half floating boom, forms a tunnel-through diode.

3. AMOLED pixel-driving circuit according to claim 2, is characterized in that: by institute's making alive on described driving transistors drain electrode and control gate, control the quantity of electric charge of described half floating boom storage, and adjustable to realize the threshold voltage of described driving transistors.

4. AMOLED pixel-driving circuit according to claim 3, is characterized in that: the threshold voltage of described driving transistors is adjusted by following process:

Charging process: the control gate of described driving transistors adds negative voltage, drain electrode adds positive voltage, and electric charge, because tunneling effect enters half floating boom, reduces the threshold voltage of described driving transistors;

Discharge process: the control gate institute making alive of described driving transistors is greater than described drain electrode institute making alive, described pn junction diode positively biased, the electric charge in described half floating boom discharges by described pn junction diode, and the threshold voltage of described driving transistors improves.

5. AMOLED pixel-driving circuit according to claim 1, is characterized in that: described the first transistor and transistor seconds are any one in polycrystalline SiTFT, amorphous silicon film transistor, Zinc oxide based film transistor and OTFT.

6. a driving method for AMOLED pixel-driving circuit as claimed in any one of claims 1 to 5, wherein, is characterized in that, comprising:

Programming phases: described the first transistor and transistor seconds conducting, described data-signal is programmed to the threshold voltage of described driving transistors;

Glow phase: described the first transistor conducting, transistor seconds turn-offs, and described data-signal is inputted the first voltage V ₁, make described Organic Light Emitting Diode luminous.

7. the driving method of AMOLED pixel-driving circuit according to claim 6, is characterized in that: before described programming phases, also comprise:

Initial phase: the first transistor and transistor seconds conducting, described data-signal input second voltage V ₂, external power source input tertiary voltage V ₃, and V ₃<V ₂, make the pn junction diode positively biased in described driving transistors, the electric charge storing to empty described driving transistors half floating boom.

8. the driving method of AMOLED pixel-driving circuit according to claim 7, is characterized in that:

In programming phases, the threshold voltage of described driving transistors is changed into:

V _th＝V _th0+ΔV _th

V in formula _thfor the threshold voltage after described driving transistors programming, V _th0initial threshold voltage while emptying electric charge for this driving transistors half floating boom, Δ V _thfor the variable quantity after this drive transistor threshold voltage programming;

In glow phase, the electric current that described Organic Light Emitting Diode flows through is:

$I=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}(V_1-V_{\mathrm{th}})=\frac{1}{2}{\mathrm{\&mu;C}}_{\mathrm{ox}}\frac{W}{L}{(V_1-V_{\mathrm{th}0}-{\mathrm{\&Delta;V}}_{\mathrm{th}})}^2$

In formula, I is the electric current that flows through Organic Light Emitting Diode and driving transistors, and μ is carrier mobility, C _oxfor unit area gate oxide electric capacity, W is driving transistors grid width, and L is that driving transistors grid are long.

9. according to the driving method of the AMOLED pixel-driving circuit described in claim 6 or 7, it is characterized in that: in programming phases, the control gate of described driving transistors adds negative voltage, drain electrode adds positive voltage, and electric charge reduces the threshold voltage of described driving transistors because tunneling effect enters half floating boom.

10. an AMOLED pel array drive system, is characterized in that, comprising:

Data-signal driving circuit, for generation of data-signal;

Sweep circuit, for generation of the first sweep signal and the second sweep signal;

Pel array, by a plurality of pixel-driving circuits of AMOLED as claimed in any one of claims 1 to 5, wherein, being matrix arrangement forms, wherein, described a plurality of pixel-driving circuit shares same external power source and ground wire, pixel-driving circuit in each row shares described the first sweep signal and the second sweep signal, the pixel-driving circuit shared data signal in each row.

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