CN103021328B - Pixel circuit for driving light emitting device to emit light and display device - Google Patents
Pixel circuit for driving light emitting device to emit light and display device Download PDFInfo
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- CN103021328B CN103021328B CN201210484941.8A CN201210484941A CN103021328B CN 103021328 B CN103021328 B CN 103021328B CN 201210484941 A CN201210484941 A CN 201210484941A CN 103021328 B CN103021328 B CN 103021328B
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Abstract
The embodiment of the invention provides a pixel circuit for driving a light emitting device to emit light and a display device which are used for improving the brightness uniformity of an area image which is displayed by the display device. The pixel circuit comprises a rechargeable sub-circuit, a drive sub-circuit, and a light-emitting control sub-circuit; the drive sub-circuit comprises a reference signal source, a driving transistor and a capacitor, wherein a grid electrode of the driving transistor is connected with the first end of the capacitor, a source electrode of the driving transistor is connected with the output end of the reference signal source, and a drain electrode of the driving transistor is connected with the first end of the light-emitting control sub-circuit; and the second end of the capacitor is connected with the rechargeable sub-circuit, and the second end of the light-emitting control sub-circuit is connected with the light emitting device.
Description
Technical field
The present invention relates to organic light emission technical field, particularly relate to a kind of image element circuit and the display device that drive luminescent device luminescence.
Background technology
Organic Light Emitting Diode (Organic Light Emitting Diode, OLED) display because of have low in energy consumption, brightness is high, cost is low, visual angle is wide, and the advantage such as fast response time, receive much concern, be widely used in organic light emission technical field.
In OLED display, there is following inevitably problem.First, for realizing each transistor of image display owing to there is structural unevenness in manufacturing process on backboard, and the unevenness of electric property and stability aspect, cause the threshold voltage V of transistor
ththere occurs drift.Secondly, transistor can cause stability to decline when long-time conducting.In addition, along with the development of OLED size-enlargement, the load correspondingly on signal wire becomes large, causes occurring voltage attenuation on signal wire, such as operating voltage V
dDchange.
When using the structure driving OLED work of the existing image element circuit for driving OLED luminescence, flow through the electric current of OLED and the threshold voltage V of driving transistors
th, the stability of driving transistors, reference voltage V
dDin one of them or wherein multiple factor is relevant.When applying identical drive singal for each pixel, the electric current that each OLED is flow through in backboard viewing area is unequal, causes the current unevenness on backboard even, thus causes brightness of image uneven.
Summary of the invention
The embodiment of the present invention provides a kind of image element circuit and the display device that drive luminescent device luminescence, in order to improve the homogeneity of display device viewing area brightness of image.
The image element circuit of the driving luminescent device luminescence that the embodiment of the present invention provides, comprising: charging electronic circuit, drive sub-circuits, and light emitting control electronic circuit;
Described drive sub-circuits comprises: derived reference signal, driving transistors and electric capacity;
Wherein, the grid of described driving transistors is connected with the first end of described electric capacity, and source electrode is connected with the output terminal of derived reference signal, drains to be connected with the first end of light emitting control electronic circuit; Second end of described electric capacity is connected with described charging electronic circuit; Second end of described light emitting control electronic circuit is connected with luminescent device;
Described charging electronic circuit is used for for described capacitor charging, and the electric capacity after described charging is for maintaining the voltage of drive transistor gate; Described light emitting control electronic circuit is for controlling described drive sub-circuits and luminescent device conducting, and drive sub-circuits drives luminescent device luminous.
Preferably, described charging electronic circuit comprises: data signal source, gate signal source, and the first switching transistor;
The drain electrode of the first switching transistor is connected with the output terminal of data signal source, and source electrode is connected with the second end of electric capacity, and grid is connected with the output terminal in gate signal source;
Described gate signal source is for controlling the first switching transistor conducting, and described data signal source is described capacitor charging.
Preferably, described light emitting control electronic circuit comprises: luminous signal source and second switch transistor;
The described source electrode of second switch transistor is connected with the drain electrode of driving transistors, drains to be connected with luminescent device, and grid is connected with the output terminal in luminous signal source;
Described luminous signal source for controlling second switch transistor turns, thus controls drive sub-circuits and luminescent device conducting, makes luminescent device luminous under the driving of described drive sub-circuits.
Preferably, described image element circuit also comprises drived control electronic circuit, and this drived control electronic circuit comprises: source driving signal, the 3rd switching transistor, and the 4th switching transistor;
The source electrode of described 3rd switching transistor is connected with the output terminal of derived reference signal, drains to be connected with the drain electrode of the 4th switching transistor, and grid is connected with the source electrode of the 4th switching transistor; The grid of described 4th switching transistor is connected with the output terminal of described source driving signal;
Described source driving signal is for controlling described 4th switching transistor conducting, thus it is luminous to control driving transistors driving luminescent device.
Preferably, described image element circuit also comprises reset subcircuit, and this reset subcircuit comprises reset signal source, the 5th open pipe transistor, with reference to reset voltage source;
The described source electrode of the 5th switching transistor is connected with the second end of electric capacity, and drain and wait that resetting to a certain reference reset voltage source with reference to resetting voltage is connected, grid is connected with the output terminal in reset signal source;
Described reset signal source controls the 5th open pipe transistor turns, and the second end of electric capacity, to the second end of electric capacity, is reset to reference to resetting voltage by the described voltage-drop loading with reference to reset voltage source output.
Preferably, described is a constant voltage source with reference to reset voltage source.
Preferably, described is derived reference signal with reference to reset voltage source, and the second end of electric capacity is reset to GND by this derived reference signal.
Preferably, described driving transistors is p-type transistor, and the positive pole of described luminescent device is connected with the second end of light emitting control electronic circuit.
Preferably, described driving transistors is n-type transistor, and the negative pole of described luminescent device is connected with the second end of light emitting control electronic circuit.
A kind of display device that the embodiment of the present invention provides, comprises the image element circuit of described driving luminescent device luminescence.
The embodiment of the present invention provides a kind of image element circuit driving luminescent device luminescence, comprising: charging electronic circuit, drive sub-circuits and light emitting control electronic circuit; Charging electronic circuit is by voltage V corresponding for data-signal
dATAbeing loaded into the two ends of electric capacity, is capacitor charging; Light emitting control electronic circuit, by the drive sub-circuits conducting be connected with light emitting control electronic circuit, capacitor discharge, by driving transistors, drives luminescent device luminous.The voltage driving luminescent device luminescence only with V
dATArelevant, with the threshold voltage V of pixel
thhave nothing to do with reference voltage, there is not the threshold voltage V of transistor (comprising driving transistors and switching transistor)
thwith the impact of reference voltage on luminescent device electric current, during different pixels input equalized data signal, the brightness of the image obtained is identical, improves the homogeneity of display device viewing area brightness of image.
Accompanying drawing explanation
Fig. 1 is image element circuit structure overall schematic corresponding to the p-type transistor that the embodiment of the present invention provides;
Fig. 2 is image element circuit concrete structure schematic diagram corresponding to the p-type transistor that the embodiment of the present invention provides;
Fig. 3 is the image element circuit structure schematic diagram with drived control function corresponding to the p-type transistor that the embodiment of the present invention provides;
The image element circuit structure schematic diagram that Fig. 4 is connected with gate signal source for drived control electronic circuit that the p-type transistor that the embodiment of the present invention provides is corresponding;
The corresponding image element circuit structure schematic diagram with reset function of p-type transistor that Fig. 5 provides for the embodiment of the present invention;
Fig. 6 is the sequential chart of the image element circuit work shown in Fig. 5 corresponding to the p-type transistor that the embodiment of the present invention provides;
The corresponding image element circuit structure schematic diagram with reset function of n-type transistor that Fig. 7 provides for the embodiment of the present invention;
Fig. 8 is the sequential chart of the image element circuit work shown in Fig. 7 corresponding to the n-type transistor that the embodiment of the present invention provides.
Embodiment
A kind of image element circuit and display device driving luminescent device luminescence that the embodiment of the present invention provides, in order to improve the homogeneity of display device viewing area brightness of image.
Image element circuit is connected with luminescent device, comprises the charging electronic circuit for realizing the functions such as charging, driving and drive sub-circuits; In the charging stage, the work of charging electronic circuit, luminescent device quits work; In glow phase, charging electronic circuit quits work, drive sub-circuits work, drives luminescent device luminous.
Driving transistors in embodiment of the present invention image element circuit and the transistor that respectively opens the light can be thin film transistor (TFT)s (Thin Film Transistor, TFT) also can be metal oxide semiconductor field effect tube (Metal OxidSemiconductor, MOS).Described driving transistors and the transistor that respectively opens the light can be n-type transistor also can be p-type transistor.Luminescent device described in the embodiment of the present invention can be Organic Light Emitting Diode OLED, organic electroluminescent device (EL) etc.
The image element circuit that the embodiment of the present invention provides, in glow phase, drive sub-circuits conducting, drives the luminescent device be attached thereto to realize luminescence display.The image element circuit that the embodiment of the present invention provides can ensure the voltage V driving the variable of the driving voltage (voltage corresponding with described driving transistors leakage current) of luminescent device luminescence only to provide with data signal source in glow phase
dATArelevant, the reference voltage V provided with reference voltage source
dD, V
sS, and the threshold voltage V of driving transistors
th0have nothing to do etc. factor.Even if there is the problem that the uneven or stability of driving transistors declines or load on signal wire is heavier when producing in the backboard of display device, all can not affect the homogeneity of viewing area electric current, thus improve the homogeneity of display device viewing area brightness of image.
The technical scheme that the embodiment of the present invention provides is illustrated below by accompanying drawing.
See Fig. 1, the image element circuit be connected with illuminator D1 part that the embodiment of the present invention provides comprises:
Charging electronic circuit 1, drive sub-circuits 2, and light emitting control electronic circuit 3;
Drive sub-circuits 2 comprises: the first reference voltage source 21, driving transistors T0 and electric capacity CST;
Wherein, the grid of driving transistors T0 is connected with the first end (A shown in Fig. 1 holds) of electric capacity CST, and source electrode is connected with the output terminal of the first reference voltage source 21, drains to be connected (as the C in Fig. 1 holds) with the first end of light emitting control electronic circuit 3;
The second end (the D end as in Fig. 1) sending out light emitting control electronic circuit 3 is connected with the first end of luminescent device D1; Second end of luminescent device D1 is connected with the second reference voltage source 22; This second reference voltage source 22 and the first reference voltage source 21 1 are high level one is low level, forms complete circuit, and image element circuit drives luminescent device luminous.The second reference voltage source 22 shown in Fig. 1 is the voltage source of low level ground connection GND.
Charging electronic circuit 1 is connected with second end (as the B in Fig. 1 holds) of electric capacity CST;
Charging electronic circuit 1 is for charging for electric capacity CST, light emitting control electronic circuit 3 is for controlling drive sub-circuits 2 and luminescent device D1 conducting, electric capacity CST discharges, the reference voltage that first reference voltage source 21 provides and electric capacity CST act on luminescent device D1 and drive luminescent device D1 luminous, and electric capacity CST is in fact for current potential that the grid maintaining driving transistors T0 is corresponding.
When driving transistors is p-type transistor, the first end of luminescent device D1 is positive pole, and the second end is negative pole.First reference voltage source is high level voltage source, as voltage V
dD, the second reference voltage source is low level voltage source, and such as voltage can be ground GND or be V
sS.
When driving transistors is n-type transistor, the first end of luminescent device D1 is negative pole, and the second end is positive pole.First reference voltage source is low level voltage source, as voltage V
sS, the second reference voltage source is high level voltage source, and such as voltage can be V
dD.Wherein, V
dD>GND>V
sS.
Principle of work below in conjunction with Fig. 1 brief description present invention pixel circuit:
Image element circuit, according to the duty of different electronic circuit, at least can successively work in write phase and glow phase according to sequential.
When image element circuit is in the write phase of data-signal, the branch road at light emitting control electronic circuit 3 place is in off state, and whole image element circuit and luminescent device D1 are in its unaccessed state, and luminescent device D1 stops luminescence.Charging electronic circuit 1 exports the voltage V corresponding with data-signal
dATA, V
dATAbe loaded into the second end B of electric capacity CST, for electric capacity CST charges.
When image element circuit is in glow phase, the branch road at light emitting control electronic circuit 3 place is in channel status, and whole image element circuit and luminescent device D1 connect, and charging electronic circuit 1 turns off with electric capacity CST; Electric capacity CST discharges, and image element circuit drives luminescent device D1 luminous by driving transistors T0.
First for p-type transistor, the image element circuit that the embodiment of the present invention provides be described for driving transistors T0 and each switching transistor below and realize driving luminous principle.It should be noted that, p-type transistor is ended under gate terminal is in high level (also namely turn off), is in conducting under low level, and reference voltage corresponding to p-type transistor is V
dD, V
dATAfor on the occasion of, the threshold voltage V of each transistor
thfor negative value.
See Fig. 2, be the pixel electrode concrete structure schematic diagram be connected with luminescent device D1, introduce the structure of each electronic circuit below.
Charging electronic circuit 1 comprises: data signal source 11, gate signal source 12, and the first switching transistor T1;
The drain electrode of the first switching transistor T1 is connected with the output terminal of data signal source 11, and source electrode is connected with the second end B of electric capacity CST, and grid is connected with the output terminal in gate signal source 12;
Gate signal source 12 is for controlling the first switching transistor T1 conducting, and data signal source 11 charges for electric capacity CST.Charging electronic circuit 1 is for charging for electric capacity CST, and the electric capacity CST after charging is for maintaining the voltage of the grid of driving transistors T0.
Drive sub-circuits 2 comprises: the first reference voltage source 21, driving transistors T0, and electric capacity CST;
Wherein, the grid of driving transistors T0 is connected with the first end (A shown in Fig. 2 holds) of electric capacity CST, and source electrode is connected with the output terminal of the first reference voltage source 21, drains to be connected with the source electrode of the second switch transistor T2 of light emitting control electronic circuit 3.Drive sub-circuits 2 is for driving luminescent device D1 luminous.
Light emitting control electronic circuit 3 comprises: luminous signal source 31 and second switch transistor T2;
The source electrode of second switch transistor T2 is connected with the drain electrode of driving transistors T0, drains to be connected with the positive pole of luminescent device D1, and grid is connected with the output terminal in luminous signal source 31; Light emitting control electronic circuit 3 is for controlling drive sub-circuits 2 and luminescent device D1 conducting, the branch road conducting at luminescent device D1 place, and drive sub-circuits 2 drives luminescent device D1 luminous.
The embodiment of the present invention, the negative pole of luminescent device D1 is connected with low level signal source.
Preferably, the negative pole of the luminescent device D1 shown in Fig. 2 is connected with ground connection (GND) signal source.
Luminescent device D1 shown in Fig. 2 is light emitting diode.
The embodiment of the present invention, the high level corresponding voltage V of the first reference voltage source 21
dD, low level corresponding voltage GND, this first reference voltage source 21 is constant voltage source.The high level corresponding voltage in gate signal source 12 is V
gATE, low level corresponding voltage is GND, and this gate signal source 12 is alternating signal source.The high level corresponding voltage V of data signal source 11
dATA, low level corresponding voltage is GND, and this data signal source 11 is alternating signal source.
Preferably, see Fig. 3, the image element circuit that the embodiment of the present invention provides also comprises drived control electronic circuit 4, for controlling the current potential of the grid point of driving transistors T0.
Drived control electronic circuit 4 specifically comprises: source driving signal 41, the 3rd switching transistor T3, and the 4th switching transistor T4;
The source electrode of the 3rd switching transistor T3 is connected with the output terminal of the first reference voltage source 21, drains to be connected with the drain electrode of the 4th switching transistor T4, and grid is connected with the source electrode of the 4th switching transistor T4; The grid of the 4th switching transistor T4 is connected with the output terminal of source driving signal 41; Source driving signal 41 is for controlling the 4th switching transistor T4 conducting, thus it is luminous to control driving transistors T0 driving luminescent device D1.
Source driving signal 41 is alternating signal source, under the control of sequential, control the 4th switching transistor T4 turn-on and turn-off.When the 4th switching transistor T4 conducting, the grid of the 3rd switching transistor T3 and drain short circuit, the 3rd switching transistor T3 becomes the connected mode of diode.When the 4th switching transistor T4 turns off, the 3rd switching transistor T3 recovers the connected mode of triode.
Preferably, source driving signal 41 can be the signal source independent of gate signal source 12 and data signal source 11, also can replace with gate signal source 12 or data signal source 11, that is, the grid of the 4th switching transistor T4 is connected with the output terminal of gate signal source 12 or data signal source 11, to simplify circuit structure.
See Fig. 4, in image element circuit, gate signal source 12 is connected with the grid of the 4th switching transistor T4.
As long as ensured before write phase as the grid of driving transistors T0 provides V
dD+ V
th3, wherein V
th3it is the threshold voltage of the 3rd switching transistor T3.4th switching transistor T4 is exactly to make the 3rd switching transistor T3 become diode from triode, ensures V
dATAbefore input, the grid voltage of driving transistors T0 is V
dD+ V
th3.
It should be noted that, light emitting control electronic circuit 3 in the image element circuit that the embodiment of the present invention provides is only the conducting and the disconnection that control luminescent device D1 and image element circuit, in order to the impact reduced and avoid luminescent device D1 voltage drop (Voled) to write data-signal.Light emitting control electronic circuit 3 in image element circuit is not limited to the structure of the light emitting control electronic circuit 3 shown in Fig. 1-Fig. 4, and the light emitting control electronic circuit 3 shown in Fig. 1-Fig. 4 also can replace with wire, and luminescent device is directly connected with image element circuit.Two kinds of connected modes all can realize write and the luminescence process of data-signal.
See Fig. 5, described image element circuit also comprises reset subcircuit 5, and this reset subcircuit 5 comprises:
Reset signal source 51, the 5th open pipe transistor T5, and with reference to reset voltage source 52;
The source electrode of the 5th switching transistor T5 is held with the second end B of electric capacity CST and is connected, and drain and wait that resetting to a certain reference reset voltage source 52 with reference to resetting voltage is connected, grid is connected with the output terminal in reset signal source 51;
Reset signal source 51 is alternating signal source.
Reset signal source 51 controls the 5th open pipe transistor T5 conducting, with reference to the voltage V that reset voltage source 52 exports
refthe the second end B being loaded into electric capacity CST holds, and is reset to the second end B end of electric capacity CST with reference to resetting voltage V
ref.With reference to resetting voltage V
refcan be GND or other a certain magnitude of voltage.
Preferably, described with reference to reset voltage source be similar to gate signal source or data signal source derived reference signal or be a constant voltage source; When described reference reset voltage source is derived reference signal, the second end B end of electric capacity CST is reset to GND.
Preferably, source driving signal 41 can be independently voltage source, also can be reset signal source 51; That is, when source driving signal 41 is reset signal source 51, the grid of the 4th switching transistor T4 is connected with the output terminal in reset signal source 51, and as shown in Figure 5, the grid of the 4th switching transistor T4 is connected with the output terminal in reset signal source 51.
Below in conjunction with the sequential chart of the image element circuit shown in the image element circuit shown in Fig. 5 and Fig. 6, each electronic circuit of image element circuit that illustrating the embodiment of the present invention provides realizes the principle of corresponding function.
Further, the present invention all illustrates so that the second end B end of electric capacity CST is reset to GND.
Image element circuit shown in Fig. 5 has the reset function of reset subcircuit, the write-in functions of data-signal of charging electronic circuit and drive sub-circuits and drives luminescent device lighting function.Each electronic circuit works under the control of sequential, and correspondingly, image element circuit comprises three working stages, is followed successively by: reseting stage, write phase, and glow phase.Each switching transistor in Fig. 5 and driving transistors are p-type transistor.
First stage: reseting stage.
See Fig. 5 and Fig. 6, sequential chart is as shown in Figure 6 known:
First reference voltage source 21 output voltage is in high level state at the three phases of image element circuit work always, and the voltage of output is V
dD.
Luminous signal source 31 shown in Fig. 5 becomes high level from low level, and the voltage of output becomes V from GND
eMISSION.The second switch transistor T2 be connected with luminous signal source 31 is in high level off state, branch road and the drive sub-circuits at luminescent device D1 place disconnect, luminescent device is in reseting stage at image element circuit and does not work, and luminescent device by the impact of image element circuit, does not realize preferably display effect.
Gate signal source 12 output voltage is high level, and the voltage of output is V
gATA, the first switching transistor T1 be connected with gate signal source 12 is in high level off state, and the data-signal of the data signal source 11 be connected with the first switching transistor T1 cannot write, and therefore, the output voltage of the data signal source 11 of reseting stage is GND.
Reset signal source 51 output voltage becomes low level from high level, and the voltage of output is by V
rESETbecome GND, the 5th switching transistor T5 be attached thereto and the 4th switching transistor T4 is in low level opening.See Fig. 5, with reference to the reference voltage V of reset voltage source 52
refthe the second end B being loaded into electric capacity CST holds.When be derived reference signal with reference to reset voltage source 52, the voltage of output is GND, and the second end B that now GND is loaded into electric capacity CST hold, and the second end B end of electric capacity CST is also that data signal input resets to earth potential.Before data wire size write phase, the current potential of electric capacity CST data input pin is GND, and the charging charge of previous frame signal in electric capacity CST does not affect the charging of current frame signal to electric capacity CST, previous frame signal on next frame Signal aspects without impact.
4th switching transistor T4 opens, and the 3rd switching transistor T3 is become the connected mode of diode from the connected mode of triode.Because the first reference voltage source 21 is in high level state always.Therefore, voltage V
dD+ V
th3be loaded into the first end of electric capacity CST, be also namely loaded into the gate terminal of driving transistors T0.
When switching transistor T3 and switching transistor T4 is in opening, for compensation for drive transistor threshold voltage V
th0drift and V
dDthe current deviation of the luminescent device D1 that decay causes.The existence of switching transistor T3 of the present invention and switching transistor T4 can make electric current and the drive transistor threshold voltage V of luminescent device D1
th0and V
dDirrelevant.
The data signal input of electric capacity CST is also that the second end B end is reset to reference potential as GND by reseting stage.The grid of also i.e. driving transistors T0 is held by electric capacity CST first end A to compensate to V
dD+ V
th3.
It should be noted that, electric capacity CST first end A holds the grid potential of also i.e. driving transistors T0 also can compensate in write phase.Such as, when grid and the gate signal source of the 4th switching transistor T4 or the output terminal of data signal source are connected, when the first switching transistor T1 opens or when the voltage of data signal source output is low level GND voltage, 4th switching transistor T4 is in opening, the 3rd switching transistor T3 is become the connected mode of diode from the connected mode of triode.Voltage V
dD+ V
th3be loaded into the first end of electric capacity CST, be also namely loaded into the gate terminal of driving transistors T0.
Subordinate phase: write phase.
See Fig. 5 and Fig. 6, sequential chart is as shown in Figure 6 known:
Luminous signal source 31 output voltage keeps high level for continuing, and output voltage is V
eMISSION, the second switch transistor T2 be connected with luminous signal source 31 is still in off state, and luminescent device D1 stops luminescence, and luminescence display is not by the impact of data-signal write;
Reset signal source 51 output voltage becomes high level from low level, and the voltage of output becomes V from GND
rESET, the 5th switching transistor T5 be attached thereto and the 4th switching transistor T4 is in high level off state.4th switching transistor T4 turns off, and is equivalent to reset circuit and image element circuit disconnects.
Gate signal source 12 output voltage becomes low level from high level, and voltage is by V
gATEbecome GND, the first switching transistor T1 conducting be connected with gate signal source 12;
Data signal source 11 output voltage becomes high level from low level, and voltage becomes V from GND
dATA, data-signal exports, corresponding voltage V
dATAbe loaded into the second end B of electric capacity CST, according to principle of charge conservation, the first end A of electric capacity CST also induces and V
dATAthe electric charge of equivalent, the voltage of the first end A of electric capacity CST becomes V
dD+ V
th3+ V
dATA, the voltage of the second end B of electric capacity CST becomes V
dATA.Namely the grid voltage of driving transistors T0 is V
dD+ V
th3+ V
dATA.Electric capacity CST is for maintaining the grid voltage of driving transistors T0.
Write phase, the voltage V that data-signal is corresponding
dATAwrite circuit, corresponding charge storage in electric capacity CST, V
dATAwith bucking voltage V
dD+ V
th3drive luminescent device luminous in glow phase.
Phase III: glow phase.
See Fig. 5 and Fig. 6, sequential chart is as shown in Figure 6 known:
Gate signal source 12 output voltage becomes high level from low level, and output voltage becomes V from GND
gATE.The the first switching transistor T1 be attached thereto turns off, and data-signal stops writing pixel circuit.Correspondingly, data signal source 11 output low level GND voltage, stops outputting data signals.
Reset signal source 51 still keeps high level, and the 5th switching transistor T5 be attached thereto turns off.
First reference voltage source 21 keeps high level, exports the voltage V that direct current signal is corresponding
dD.
That is, glow phase, reset subcircuit disconnects with charging electronic circuit and image element circuit.The 3rd switching transistor T3 and the 4th switching transistor T4 that belong to drived control electronic circuit also disconnect with image element circuit.
Luminous signal source 31 becomes low level from high level, and output voltage is by V
eMISSIONbecome GND, the second switch transistor T2 conducting under low level be attached thereto, the branch road conducting at the luminescent device D1 be connected with second switch transistor T2 and driving transistors T0 place.
Be kept at the voltage V of electric capacity CST first end
dD+ V
th3+ V
dATAbe loaded into the grid of driving transistors T0, the source voltage of driving transistors T0 is V
s=V
dD, the voltage V of driving transistors T0 grid
g=V
dD+ V
th3+ V
dATA.
Now, the voltage difference between the source electrode of driving transistors T0 and grid is V
gs=V
g-V
s=(V
dD+ V
th3+ V
dATA)-V
dD=V
th3+ V
dATA.
Because driving transistors T0 works in state of saturation, according to state of saturation current characteristics, the leakage current of known driving transistors T0 meets following formula:
Wherein i
dfor the leakage current of driving transistors T0, V
gsfor the voltage between the grid of driving transistors T0 and source electrode, K is structural parameters, and in identical structure, this numerical value is relatively stable, V
th0for the threshold voltage of driving transistors.
Because driving transistors is identical with the formation material of the structure of each switching transistor, threshold voltage is similar to identical, i.e. V
th3=V
th0.Obtained by formula (1-2)
It can thus be appreciated that, flow through the drain electrode i of driving transistors T0
dthe V only provided with data signal source 11
dATArelevant, with V
th0and V
dDirrelevant.This leakage current i
ddrive luminescent device D1 luminous, the threshold voltage V of the driving transistors that the electric current flowing through OLED does not cause because of backplane manufacturing process reason
th0uneven caused electric current is different, thus causes brightness to change.Also can not because of V
dDdue to V that load-reason causes on signal wire
dDiR Drop and the curent change caused.Can also improve due to V simultaneously
th0decline and the curent change flowing through luminescent device that causes, thus cause brightness to change, make luminescent device bad stability.
When each switching transistor and driving transistors T0 are n-type transistor, the image element circuit structure shown in circuit structure and Fig. 1 to Fig. 5 is similar, and as shown in Figure 7, the voltage that just the first reference voltage source provides is low level voltage V
sS, the negative pole of luminescent device is connected with light emitting control electronic circuit, and positive pole is connected with the high level voltage of the second reference voltage source 22, such as V
dD.
For the image element circuit of N-shaped driving transistors and N-shaped switching transistor, V
dATAand V
thfor on the occasion of.Each switching transistor turns off under low level, conducting under high level.
Sequential chart shown in sequential chart from Fig. 6 is different.
The voltage that first reference voltage source 21 exports is in low level always, and output voltage is V
sS.
Working timing figure below in conjunction with the image element circuit shown in the structure of the image element circuit be connected with luminescent device D1 shown in Fig. 7 and Fig. 8 introduces the principle of work of each working stage of image element circuit successively.
First stage: reseting stage.
See Fig. 7 and Fig. 8, sequential chart is as shown in Figure 8 known:
First reference voltage source 21 output voltage is in low level state at the three phases of image element circuit work always, and the voltage of output is V
sS.
Luminous signal source 31 shown in Fig. 7 becomes low level from high level, and the voltage of output is by V
eMISSIONbecome GND.The second switch transistor T2 be connected with luminous signal source 31 is in low level off state, drive sub-circuits controls image element circuit and luminescent device D1 disconnects, luminescent device D1 is in reseting stage at image element circuit and does not work, luminescent device D1 by the impact that image element circuit resets, does not realize preferably display effect.
Gate signal source 12 output voltage is low level, the voltage exported is GND, the the first switching transistor T1 be connected with gate signal source 12 is in low level off state, the data-signal of the data signal source 11 be connected with the first switching transistor T1 cannot write, therefore, the output voltage of the data signal source 11 of reseting stage is GND.
Reset signal source 51 output voltage becomes high level from low level, and the voltage of output becomes V from GND
rESET, the 5th switching transistor T5 be attached thereto and the 4th switching transistor T4 is in high level opening.See Fig. 7, with reference to the reference voltage V of reset voltage source 52
refthe the second end B being loaded into electric capacity CST holds.When be derived reference signal with reference to reset voltage source 52, the voltage of output is GND, and the second end B that now GND is loaded into electric capacity CST hold, and the second end B end of electric capacity CST is also that data signal input resets to earth potential.Before data wire size write phase, the current potential of electric capacity CST data input pin is GND, and the charging charge of previous frame signal in electric capacity CST does not affect the charging of current frame signal to electric capacity CST, previous frame signal on next frame Signal aspects without impact.Reference reset voltage source 52 is constant voltage source.
4th switching transistor T4 opens, and the 3rd switching transistor T3 is become the connected mode of diode from the connected mode of triode.Because the first reference voltage source 21 is in low level state always.Therefore, voltage V
sS+ V
th3be loaded into the first end of electric capacity CST, be also namely loaded into the gate terminal of driving transistors T0.
When switching transistor T3 and switching transistor T4 is in opening, for compensation for drive transistor threshold voltage V
th0drift and V
sSthe current deviation of the luminescent device D1 that decay causes.The existence of switching transistor T3 of the present invention and switching transistor T4 can make electric current and the drive transistor threshold voltage V of luminescent device D1
th0and V
sSirrelevant.
The data signal input of electric capacity CST is also that the second end B end is reset to reference potential as GND by reseting stage.The grid of also i.e. driving transistors T0 is held by electric capacity CST first end A to compensate to V
sS+ V
th3.
It should be noted that, electric capacity CST first end A holds the grid potential of also i.e. driving transistors T0 also can compensate in write phase.Such as, when grid and the gate signal source of the 4th switching transistor T4 or the output terminal of data signal source are connected, when the first switching transistor T1 opens or when the voltage of data signal source output is high level voltage, 4th switching transistor T4 is in opening, the 3rd switching transistor T3 is become the connected mode of diode from the connected mode of triode.Voltage V
sS+ V
th3be loaded into the first end of electric capacity CST, be also namely loaded into the gate terminal of driving transistors T0.
Subordinate phase: write phase.
See Fig. 7 and Fig. 8, sequential chart is as shown in Figure 8 known:
Luminous signal source 31 output voltage keeps low level for continuing, output voltage is GND, and the second switch transistor T2 be connected with luminous signal source 31 is still in off state, and luminescent device D1 and image element circuit disconnect, stop luminous, luminescence display is not by the impact of pixel circuit data signal write;
Reset signal source 51 output voltage becomes low level from high level, and the voltage of output is by V
rESETbecome GND, the 5th switching transistor T5 be attached thereto and the 4th switching transistor T4 is in low level off state.4th switching transistor T4 turns off, and is equivalent to reset circuit and image element circuit disconnects.
Gate signal source 12 output voltage becomes high level from low level, and voltage becomes V from GND
gATE, the first switching transistor T1 conducting be connected with gate signal source 12;
Data signal source 11 output voltage becomes high level from low level, and voltage becomes V from GND
dATA, data-signal exports, corresponding voltage V
dATAbe loaded into the second end B of electric capacity CST, according to principle of charge conservation, the first end A of electric capacity CST also induces and V
dATAthe electric charge of equivalent, the voltage of the first end A of electric capacity CST becomes V
sS+ V
th3+ V
dATA, the voltage of the second end B of electric capacity CST becomes V
dATA.Namely the grid voltage of driving transistors T0 is V
sS+ V
th3+ V
dATA.Electric capacity CST is for maintaining the grid voltage of driving transistors T0.
Write phase, the voltage V that data-signal is corresponding
dATAwrite circuit, corresponding charge storage in electric capacity CST, V
dATAwith bucking voltage V
sS+ V
th3drive luminescent device luminous in glow phase.
Phase III: glow phase.
See Fig. 7 and Fig. 8, sequential chart is as shown in Figure 7 known:
Gate signal source 12 output voltage becomes low level from high level, and output voltage is by V
gATEbecome GND.The the first switching transistor T1 be attached thereto turns off, and data-signal stops writing pixel circuit.Correspondingly, data signal source 11 output low level GND voltage, stops outputting data signals.
Reset signal source 51 still keeps low level, and the 5th switching transistor T5 be attached thereto turns off.
First reference voltage source 21 keeps low level, exports the voltage V that direct current signal is corresponding
sS.
That is, glow phase, reset subcircuit disconnects with charging electronic circuit and image element circuit.The 3rd switching transistor T3 and the 4th switching transistor T4 that belong to drived control electronic circuit also disconnect with image element circuit.
Luminous signal source 31 becomes high level from low level, and output voltage becomes V from GND
eMISSION, the second switch transistor T2 conducting under high level be attached thereto, controls luminescent device D1 and image element circuit conducting, particularly, controls luminescent device D1 and the branch road conducting of drive sub-circuits place.
Be kept at the voltage V of electric capacity CST first end
sS+ V
th3+ V
dATAbe loaded into the grid of driving transistors T0, the source voltage of driving transistors T0 is V
s=V
sS, the voltage V of driving transistors T0 grid
g=V
sS+ V
th3+ V
dATA.
Now, the voltage difference between the source electrode of driving transistors T0 and grid is V
gs=V
g-V
s=(V
sS+ V
th3+ V
dATA)-V
sS=V
th3+ V
dATA.
Because driving transistors T0 works in state of saturation, according to state of saturation current characteristics, the leakage current of known driving transistors T0 meets following formula:
Wherein i
dfor the leakage current of driving transistors T0, V
gsfor the voltage between the grid of driving transistors T0 and source electrode, K is structural parameters, and in identical structure, this numerical value is relatively stable, V
th0for the threshold voltage of driving transistors.
Because driving transistors is identical with the formation material of the structure of each switching transistor, threshold voltage is similar to identical, i.e. V
th3=V
th0.Obtained by formula (1-4)
It can thus be appreciated that, flow through the drain electrode i of driving transistors T0
dthe V only provided with data signal source 11
dATArelevant, with V
th0and V
sSirrelevant.This leakage current i
ddrive luminescent device D1 luminous, the threshold voltage V of the driving transistors that the electric current flowing through OLED does not cause because of backplane manufacturing process reason
th0uneven caused electric current is different, thus causes brightness to change.Also can not because of V
sSdue to V that load-reason causes on signal wire
sSiR Drop and the curent change caused.Can also improve due to V simultaneously
th0decline and the curent change flowing through luminescent device that causes, thus cause brightness to change, make luminescent device bad stability.
The embodiment of the present invention also provides a kind of display device, comprises above-mentioned image element circuit.
This display device can be the display device such as ORGANIC ELECTROLUMINESCENCE DISPLAYS oled panel, OLED display, OLED TV or Electronic Paper.
Derived reference signal of the present invention and reference reset signal source are DC signal source, keep direct current signal always; Reset signal source, gate signal source, data signal source, source driving signal, and luminous signal source is AC signal, changes according to the change of sequential.
In addition, above-mentioned various transistor (comprising switching transistor and driving transistors) source electrode is identical with the manufacture craft of drain electrode, can exchange nominally, and it can change nominally according to the direction of voltage.And the type of each transistor can be identical in same image element circuit, also can be different, only need adjust corresponding sequential low and high level according to himself threshold voltage feature.Certainly, preferred mode is, the transistor that the grid start signal source of needs is identical, and its type is identical.More preferred, in same image element circuit, the type of all crystals pipe is identical (comprising switching transistor and driving transistors), is n-type transistor or p-type transistor.
In sum, the embodiment of the present invention provides a kind of image element circuit for driving the luminescent device be attached thereto luminous, and image element circuit provided by the invention not only ensures to drive the electric current of luminescent device D1 and reference voltage by image element circuit, and (reference voltage can be V
dDor V
sS) irrelevant, with the threshold voltage V of driving transistors
th0also have nothing to do, and also have nothing to do with the threshold voltage of each switching transistor.Avoid the driving transistors that causes because of backplane manufacturing process reason or/and switch transistor structure difference to some extent, thus the electric current of uneven the caused luminescent device of threshold voltage is different.And avoid V
dDor V
sSthe IR Drop that signal wire causes due to load-reason and the curent change caused.The curent change flowing through luminescent device and brightness change that cause due to threshold voltage decline can also be improved simultaneously, make the problem of luminescent device bad stability.Further, light emitting control electronic circuit is when the write phase of data-signal, and control image element circuit and luminescent device disconnect, and reduce and avoid image element circuit in write phase, reducing and avoid the impact that luminescent device D1 voltage drop (Voled) writes data-signal.
Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (7)
1. drive an image element circuit for luminescent device luminescence, it is characterized in that, comprising: charging electronic circuit, drive sub-circuits, drived control electronic circuit, and light emitting control electronic circuit;
Described drive sub-circuits comprises: derived reference signal, driving transistors and electric capacity;
Wherein, the grid of described driving transistors is connected with the first end of described electric capacity, and source electrode is connected with the output terminal of derived reference signal, drains to be connected with the first end of light emitting control electronic circuit; Second end of described electric capacity is connected with described charging electronic circuit; Second end of described light emitting control electronic circuit is connected with luminescent device;
Described charging electronic circuit is used for for described capacitor charging, and the electric capacity after described charging is for maintaining the voltage of drive transistor gate; Described light emitting control electronic circuit is for controlling described drive sub-circuits and luminescent device conducting, and drive sub-circuits drives luminescent device luminous;
Described drived control electronic circuit comprises: source driving signal, the 3rd switching transistor, and the 4th switching transistor;
The source electrode of described 3rd switching transistor is connected with the output terminal of derived reference signal, drains to be connected with the drain electrode of the 4th switching transistor, and grid is connected with the source electrode of the 4th switching transistor; The grid of described 4th switching transistor is connected with the output terminal of described source driving signal; Described source driving signal is for controlling described 4th switching transistor conducting, thus it is luminous to control driving transistors driving luminescent device.
2. image element circuit according to claim 1, is characterized in that, described charging electronic circuit comprises: data signal source, gate signal source, and the first switching transistor;
The drain electrode of the first switching transistor is connected with the output terminal of data signal source, and source electrode is connected with the second end of electric capacity, and grid is connected with the output terminal in gate signal source;
Described gate signal source is for controlling the first switching transistor conducting, and described data signal source is described capacitor charging.
3. image element circuit according to claim 2, is characterized in that, described light emitting control electronic circuit comprises: luminous signal source and second switch transistor;
The described source electrode of second switch transistor is connected with the drain electrode of driving transistors, drains to be connected with luminescent device, and grid is connected with the output terminal in luminous signal source;
Described luminous signal source for controlling second switch transistor turns, thus controls drive sub-circuits and luminescent device conducting, makes luminescent device luminous under the driving of described drive sub-circuits;
Described driving transistors is p-type transistor, and the positive pole of described luminescent device is connected with the second end of light emitting control electronic circuit; Or described driving transistors is n-type transistor, the negative pole of described luminescent device is connected with the second end of light emitting control electronic circuit.
4. image element circuit according to claim 1, is characterized in that, described image element circuit also comprises reset subcircuit, and this reset subcircuit comprises reset signal source, the 5th switching transistor, with reference to reset voltage source;
The described source electrode of the 5th switching transistor is connected with the second end of electric capacity, and drain and wait that resetting to a certain reference reset voltage source with reference to resetting voltage is connected, grid is connected with the output terminal in reset signal source;
Described reset signal source controls the 5th switching transistor conducting, and the second end of electric capacity, to the second end of electric capacity, is reset to reference to resetting voltage by the described voltage-drop loading with reference to reset voltage source output.
5. image element circuit according to claim 4, is characterized in that, described is a constant voltage source with reference to reset voltage source.
6. image element circuit according to claim 4, is characterized in that, described is derived reference signal with reference to reset voltage source, and the second end of electric capacity is reset to GND by this derived reference signal.
7. a display device, is characterized in that, comprises the image element circuit described in any one of claim 1-6.
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| CN104050919B (en) * | 2014-06-18 | 2016-03-16 | 京东方科技集团股份有限公司 | Image element circuit and display device |
| CN105067012A (en) * | 2015-07-03 | 2015-11-18 | 复旦大学 | Method for testing performance of stable thin film transistor sensor |
| KR102650339B1 (en) * | 2016-12-27 | 2024-03-21 | 엘지디스플레이 주식회사 | Electro-luminecense display apparatus |
| CN110136648B (en) * | 2019-05-14 | 2020-10-16 | 深圳市华星光电半导体显示技术有限公司 | Pixel circuit and OLED display panel |
| CN111415620B (en) * | 2020-03-31 | 2021-08-13 | 合肥京东方显示技术有限公司 | Pixel circuit, driving method thereof and display device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1677470A (en) * | 2004-03-10 | 2005-10-05 | 三星Sdi株式会社 | Electroluminescent display device, pixel circuit therefor, and driving method thereof |
| JP2005326793A (en) * | 2004-05-17 | 2005-11-24 | Eastman Kodak Co | Display device |
| CN1975843A (en) * | 2005-11-30 | 2007-06-06 | 株式会社日立显示器 | Image display device |
| CN101127181A (en) * | 2006-08-17 | 2008-02-20 | 精工爱普生株式会社 | Electro-optical device and electronic apparatus |
| CN101192373A (en) * | 2006-11-27 | 2008-06-04 | 奇美电子股份有限公司 | Organic light emitting display and voltage compensation technology organic light emitting pixel |
| CN202905118U (en) * | 2012-11-23 | 2013-04-24 | 京东方科技集团股份有限公司 | Pixel circuit driving luminescent device to carry out light emission and display apparatus |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006309104A (en) * | 2004-07-30 | 2006-11-09 | Sanyo Electric Co Ltd | Active-matrix-driven display device |
-
2012
- 2012-11-23 CN CN201210484941.8A patent/CN103021328B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1677470A (en) * | 2004-03-10 | 2005-10-05 | 三星Sdi株式会社 | Electroluminescent display device, pixel circuit therefor, and driving method thereof |
| JP2005326793A (en) * | 2004-05-17 | 2005-11-24 | Eastman Kodak Co | Display device |
| CN1975843A (en) * | 2005-11-30 | 2007-06-06 | 株式会社日立显示器 | Image display device |
| CN101127181A (en) * | 2006-08-17 | 2008-02-20 | 精工爱普生株式会社 | Electro-optical device and electronic apparatus |
| CN101192373A (en) * | 2006-11-27 | 2008-06-04 | 奇美电子股份有限公司 | Organic light emitting display and voltage compensation technology organic light emitting pixel |
| CN202905118U (en) * | 2012-11-23 | 2013-04-24 | 京东方科技集团股份有限公司 | Pixel circuit driving luminescent device to carry out light emission and display apparatus |
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