CN203165421U - Pixel circuit, array substrate and display device - Google Patents
Pixel circuit, array substrate and display device Download PDFInfo
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- CN203165421U CN203165421U CN2013201288252U CN201320128825U CN203165421U CN 203165421 U CN203165421 U CN 203165421U CN 2013201288252 U CN2013201288252 U CN 2013201288252U CN 201320128825 U CN201320128825 U CN 201320128825U CN 203165421 U CN203165421 U CN 203165421U
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Abstract
The utility model provides a pixel circuit, an array substrate and a display device, belonging to the technical field of organic luminescent display. The pixel circuit of the utility model comprises a driving transistor, a first switch transistor, a storage capacitor and a luminescent device as well as a threshold compensating circuit, wherein the threshold compensating circuit is composed of a second switch transistor, a third switch transistor, a fourth switch transistor and a coupling capacitor, and can effectively compensate threshold voltage non-uniformity of the driving transistor. The array substrate of the utility model comprises the pixel circuit and is more stable in performance. The display device of the utility model comprises the array substrate, and is greatly improved in image uniformity.
Description
Technical field
The utility model belongs to the organic light emitting display technical field, is specifically related to a kind of image element circuit, array base palte and display device.
Background technology
Organic light emitting display (Organic Light Emitting Diode, OLED) compare present main flow display technique Thin Film Transistor-LCD (Thin Film Transisitor Liquid Crystal Display, TFT-LCD), having advantages such as wide viewing angle, high brightness, high-contrast, low energy consumption, volume be more frivolous, is the focus that present flat panel display is paid close attention to.
The driving method of organic light emitting display is divided into two kinds of passive matrix type (PM, Passive Matrix) and active-matrix formulas (AM, Active Matrix).Drive and compare passive matrix type, the active-matrix formula drive have show contain much information, low in energy consumption, device lifetime long, the picture contrast advantages of higher.The equivalent electrical circuit of the pixel cell driving circuit of a kind of active-matrix formula organic light emitting display of prior art as shown in Figure 1, comprising: the first switching transistor M1, driving transistors M2, memory capacitance C1 and luminescent device D1.Wherein, the drain electrode of the first switching transistor M1 is connected with the grid of driving transistors M2; The grid of driving transistors M2 connects the end of memory capacitance C1 simultaneously, and its source electrode is connected with the memory capacitance C1 other end, and its drain electrode is connected with luminescent device D1.The first switching transistor M1 opens when grid is scanned signal Vscan (n) gating, introduces data-signal Vdata from source electrode.Driving transistors M2 is generally operational in the saturation region, and its gate source voltage Vgs has determined to flow through the size of its electric current, and then provides stable electric current for luminescent device D1.Vgs=Vdata-VD1 wherein, VD1 is the cut-in voltage of luminescent device D1, VDD is voltage stabilizing or stabilized current supply, connects driving transistors M2, is used for luminescent device D1 is provided the luminous needed energy.And the effect of memory capacitance C1 is keep driving transistors M2 grid voltage in the time of a frame stable.
When first high level of sweep signal Vscan (n) began, n is capable, and pixel cell was strobed, and the first switching transistor M1 in this row pixel cell is opened, and introduced data-signal and drove Vdata, and luminescent device D1 begins luminous.High level by driving data signal Vdata is finished luminous memory capacitance C1 in this row pixel cell is charged of luminescent device D1, afterwards, closes the first switching transistor M1 of this row pixel cell by first low level of sweep signal Vscan (n).At this moment, memory capacitance C1 keeps the voltage in when charging, keeps the stable electric current of driving transistors M2 output of this row pixel cell, makes that the organic light emitting diode D1 of this row pixel cell continues luminously to finish up to a frame time.One frame time was generally with the double time interval that is scanned signal gating of delegation's pixel cell.
After the charging of the capable pixel cell of n is finished, the capable pixel cell of sweep signal gating n+1, the first switching transistor M1 of the capable pixel cell of n+1 is opened, introduce the driving data signal and carry out same charging process, charging is finished the back and is kept voltage when charging by the memory capacitance C1 in the pixel cell, keep driving tube output steady current, make that the luminescent device D1 of the capable pixel cell of n+1 continues luminously to finish up to a frame time.So go down in regular turn, after charging is finished to last column pixel cell, just rescan charging since the first row pixel cell again.
Although the prior art pixel unit circuit is widely used, but it is still unavoidable to exist following problem: drift can appear along with the increase of service time in the threshold voltage vt h of driving transistors M2, thereby cause occurring changing at the Vgs of same data drive signal Vdata, be electric current (brightness just) difference of luminescent device D1, thereby will influence picture homogeneity and the luminous mass thereof of whole organic light emitting display.
The utility model content
Technical problem to be solved in the utility model comprises, at in the existing pixel unit circuit owing to reasons such as drive transistor threshold voltage drift cause the circuit instability, cause the picture homogeneity of organic light emitting display and the problem of luminous mass difference thereof, a kind of unevenness of the threshold voltage of compensation for drive transistor effectively is provided, makes image element circuit, array base palte and the display device that the picture homogeneity of organic light emitting display improves.
The technical scheme that solution the utility model technical matters adopts is a kind of image element circuit, comprising: driving transistors, first switching transistor, memory capacitance, luminescent device pipe and threshold compensation circuitry; Described threshold compensation circuitry is made of second switch transistor, the 3rd switching transistor, the 4th switching transistor and coupling capacitance;
The grid of described first switching transistor connects first sweep signal, the source electrode of described first switching transistor connects the data-signal input end, and the drain electrode of described first switching transistor connects first end and the transistorized source electrode of second switch of memory capacitance first end, coupling capacitance;
The second termination power voltage of described memory capacitance connects the source electrode of described driving transistors simultaneously;
The transistorized grid of described second switch connects the grid that second sweep signal connects described the 3rd switching transistor simultaneously, and it is extreme that described second switch transistor drain connects power-;
The source electrode of described the 3rd switching transistor connects the grid of described driving transistors, and the drain electrode that the drain electrode of described the 3rd switching transistor connects described driving transistors connects the source electrode of described the 4th switching transistor simultaneously;
The grid of described the 4th switching transistor connects first control signal, and the drain electrode of described the 4th switching transistor connects described luminescent device;
Second end of described coupling capacitance links to each other with the grid of described driving transistors.
In the image element circuit of the present utility model, the threshold compensation circuitry that second switch transistor, the 3rd switching transistor, the 4th switching transistor and coupling capacitance constitute, the threshold voltage shift that is used for compensation for drive transistor, the unevenness of compensation for drive transistor threshold voltage makes the picture homogeneity of organic light emitting display improve effectively.
Preferably, described first switching transistor, second switch transistor, the 3rd switching transistor, the 4th switching transistor and described driving transistors are the N-type thin film transistor (TFT).
Preferably, described luminescent device is Organic Light Emitting Diode.
The technical scheme that solution the utility model technical matters adopts is a kind of array base palte, and it comprises above-mentioned image element circuit.
Owing to comprise above-mentioned image element circuit in the array base palte of the present utility model, so its stable performance.
The technical scheme that solution the utility model technical matters adopts is a kind of display device, and it comprises above-mentioned array base palte.
Owing to comprise above-mentioned array base palte in the display device of the present utility model, so its picture homogeneity height.
Description of drawings
Fig. 1 is the schematic diagram of existing image element circuit;
The circuit diagram of the image element circuit that Fig. 2 provides for embodiment of the present utility model; And
Fig. 3 is the sequential chart of image element circuit among Fig. 2.
Wherein Reference numeral is: M1, first switching transistor; DTFT, driving transistors; M2, second switch transistor; M3, the 3rd switching transistor; M4, be the 4th switching transistor; C1, memory capacitance; C2, coupling capacitance; D1, luminescent device; Vdata, data-signal; Vscan(n), first sweep signal; Vscan(n-1), second sweep signal; EM, first control signal.
Embodiment
For making those skilled in the art understand the technical solution of the utility model better, below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
Embodiment 1:
Present embodiment provides a kind of image element circuit, as shown in Figure 2, comprising: driving transistors DTFT, the first switching transistor M1, memory capacitance C1, luminescent device and threshold compensation circuitry; Described threshold compensation circuitry is made of second switch transistor M2, the 3rd switching transistor M3, the 4th switching transistor M4 and coupling capacitance C2;
The M1 grid of described first switching transistor meets the first sweep signal Vscan(n), source electrode meets data-signal input end Vdata, and drain electrode connects first end of memory capacitance C1 first end, coupling capacitance C2 and the source electrode of second switch transistor M2;
The second termination power voltage Vdd of described memory capacitance C1 connects the source electrode of described driving transistors DTFT simultaneously;
The grid of described second switch transistor M2 connects the grid that the second sweep signal Vscan (n-1) meets described the 3rd switching transistor M3 simultaneously, and drain electrode meets the extreme Vss of power-;
The source electrode of described the 3rd switching transistor M3 connects the grid of described driving transistors DTFT, and the drain electrode that drain electrode meets described driving transistors DTFT connects the source electrode of described the 4th switching transistor M4 simultaneously;
The grid of described the 4th switching transistor M4 meets the first control signal EM, and drain electrode meets described luminescent device D1;
Second end of described coupling capacitance C2 links to each other with the grid of described driving transistors DTFT.
Particularly, described luminescent device D1 is Organic Light Emitting Diode, the described first switching transistor M1, second switch transistor M2, the 3rd switching transistor M3, the 4th switching transistor M4 and described driving transistors DTFT are the N-type thin film transistor (TFT), alternatively, all switching tubes only play switch, also can be the P transistor npn npn, the signal of conducting or on-off switching tube adjusts accordingly and gets final product.
Specify the course of work of this image element circuit below.
In conjunction with image element circuit shown in Figure 2 and the sequential chart among Fig. 3, its course of work is divided 3 stages: preliminary filling stage, compensated stage and glow phase.
Phase one is preliminary filling stage C, when the capable pixel cell of sweep signal gating n-1, the second sweep signal Vscan (n-1) of the capable pixel cell correspondence of n-1 is high level, second switch transistor M2, the 3rd switching transistor M3 are held open, and the first sweep signal Vscan(n of the capable pixel cell correspondence of n) be low level, the first switching transistor M1 closes, and the first control signal EM leads to low level, and the 4th switching transistor M4 also keeps closing.At this moment, the voltage that the A of source electrode place of second switch transistor M2 is ordered, and the voltage that the B of grid place of driving transistors DTFT is ordered all begins to descend, the electric charge that coupling capacitance C2 stores discharges, the voltage at coupling capacitance C2 two ends drops to the threshold voltage vt h of driving transistors DTFT at this moment, the voltage of ordering until A drops to 0, the voltage that B is ordered then drops to the threshold voltage vt h of driving transistors DTFT, thereby driving transistors DTFT closes, and the voltage swing at coupling capacitance C2 two ends also is changed to the voltage difference Vth of 2 of A, B.
Subordinate phase is compensated stage D, when the capable pixel cell of sweep signal gating n, the second sweep signal Vscan (n-1) of the capable pixel cell correspondence of n-1 is low level, second switch transistor M2, the 3rd switching transistor M3 close, and the first sweep signal Vscan (n) of the capable pixel cell correspondence of n is high level, the first switching transistor M1 opens, and introduces the data drive signal Vdata on the data line, and memory capacitance C1 is charged to store this data drive signal Vdata.Subsequently, data-signal Vdata makes the A point voltage be raised to Vdata, because the effect of coupling capacitance C2, the voltage that film crystal tube grid B is ordered raises and becomes Vdata+Vth, drives thin film transistor (TFT) and keeps the conducting critical conditions.
Phase III is glow phase E: the first control signal EM connects high level and controls the 4th switching transistor M4 unlatching, because supply voltage Vdd is much larger than data voltage Vdata, therefore driving transistors DTFT opens, and supply voltage Vdd drives to luminescent device D1 output current by driving transistors M2 has luminescent device D1 luminous.
The electric current that flows through driving transistors DTFT this moment can be used following equation expression:
I=k (Vgs-Vth)
2Wherein k=1/2* μ * Cox*W/L is constant ... ..(1)
The gate source voltage Vgs=Vg-Vs of driving transistors M2.The grid voltage Vg of driving transistors M2 is B point voltage Vdata+Vth, and source voltage Vs is that the C point voltage is the cut-in voltage V of luminescent device D1 at this moment
D1Therefore, the gate source voltage Vgs of driving transistors M2 is:
Vgs=Vdata+Vth-V
D1......（2）
Formula (2) substitution (1) is drawn:
I=k(Vgs-Vth)
2=k(Vdata+Vth-V
D1-Vth)
2=k(Vdata-V
D1)
2......（3）
From formula (3) as can be seen, the current value and its variations in threshold voltage that flow through driving transistors DTFT are irrelevant, that is to say, even through using for a long time, the threshold voltage of driving transistors DTFT drifts about, but therefore the electric current that flows through driving transistors DTFT can not be affected yet, and has guaranteed the luminous mass of luminescent device D1 yet.Correspondingly, because the luminous mass of luminescent device D1 is guaranteed in the single image element circuit, this circuit is the unevenness of compensation for drive transistor threshold voltage effectively, make the picture homogeneity of display device improve, and need not to carry out threshold voltage compensation by the external compensation circuit, thereby research and development and manufacturing cost have been reduced.And the sequential of this pixel is simple, realizes easily.
Preferably, described first switching transistor, second switch transistor, the 3rd switching transistor the 4th switching transistor and described driving transistors are the N-type thin film transistor (TFT).
Preferably described luminescent device is Organic Light Emitting Diode, and other luminescent devices also are fine certainly.
Embodiment 2:
Present embodiment provides array base palte, comprises many data lines, multi-strip scanning line, and described data line and sweep trace cross arrangement are provided with image element circuit among the embodiment 1 at infall.
Present embodiment has the threshold compensation circuitry in the image element circuit among the embodiment 1, can effectively compensate the unevenness of driving transistors DTFT threshold voltage, makes that the array base palte performance in the present embodiment is more stable.
Embodiment 3:
Present embodiment provides a kind of display device, and the organic light-emitting display device array base palte in the described display device is not described in detail as described in example 2 above herein.
Certainly this display device can comprise in the present embodiment: any product or parts with Presentation Function such as oled panel, mobile phone, panel computer, televisor, display, notebook computer, digital album (digital photo frame), navigating instrument.
Because the array base palte with above-mentioned display device is so the picture homogeneity of the display device of present embodiment obviously improves.
Be understandable that above embodiment only is the illustrative embodiments that adopts for principle of the present utility model is described, yet the utility model is not limited thereto.For those skilled in the art, under the situation that does not break away from spirit of the present utility model and essence, can make various modification and improvement, these modification and improvement also are considered as protection domain of the present utility model.
Claims (5)
1. image element circuit comprises: first switching transistor, memory capacitance, driving transistors, luminescent device and threshold compensation circuitry, it is characterized in that,
Described threshold compensation circuitry comprises: second switch transistor, the 3rd switching transistor, the 4th switching transistor and coupling capacitance;
The grid of described first switching transistor connects first sweep signal, the source electrode of described first switching transistor connects the data-signal input end, and the drain electrode of described first switching transistor connects first end and the transistorized source electrode of second switch of memory capacitance first end, coupling capacitance;
The second termination power voltage of described memory capacitance connects the source electrode of described driving transistors simultaneously;
The transistorized grid of described second switch connects the grid that second sweep signal connects described the 3rd switching transistor simultaneously, and it is extreme that described second switch transistor drain connects power-;
The source electrode of described the 3rd switching transistor connects the grid of described driving transistors, and the drain electrode that the drain electrode of described the 3rd switching transistor connects described driving transistors connects the source electrode of described the 4th switching transistor simultaneously;
The grid of described the 4th switching transistor connects first control signal, and the drain electrode of described the 4th switching transistor connects described luminescent device;
Second end of described coupling capacitance links to each other with the grid of described driving transistors.
2. image element circuit according to claim 1 is characterized in that, described first switching transistor, second switch transistor, the 3rd switching transistor, the 4th switching transistor and described driving transistors are the N-type thin film transistor (TFT).
3. image element circuit according to claim 1 and 2 is characterized in that, described luminescent device is Organic Light Emitting Diode.
4. an array base palte is characterized in that, comprises any one image element circuit described in claim 1 to 3.
5. a display device is characterized in that, comprises array base palte as claimed in claim 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013201288252U CN203165421U (en) | 2013-03-20 | 2013-03-20 | Pixel circuit, array substrate and display device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013201288252U CN203165421U (en) | 2013-03-20 | 2013-03-20 | Pixel circuit, array substrate and display device |
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| CN203165421U true CN203165421U (en) | 2013-08-28 |
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| CN2013201288252U Expired - Lifetime CN203165421U (en) | 2013-03-20 | 2013-03-20 | Pixel circuit, array substrate and display device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103208254A (en) * | 2013-03-20 | 2013-07-17 | 合肥京东方光电科技有限公司 | Pixel circuit and driving method thereof, array substrate and display device |
| WO2015062298A1 (en) * | 2013-11-04 | 2015-05-07 | 京东方科技集团股份有限公司 | Oled pixel circuit and driving method thereof, and display device |
| CN108520718A (en) * | 2018-04-18 | 2018-09-11 | 京东方科技集团股份有限公司 | A kind of pixel data compensation method of display device and device, display device |
| CN111243504A (en) * | 2018-11-29 | 2020-06-05 | 昆山工研院新型平板显示技术中心有限公司 | Pixel driving circuit and display device |
-
2013
- 2013-03-20 CN CN2013201288252U patent/CN203165421U/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103208254A (en) * | 2013-03-20 | 2013-07-17 | 合肥京东方光电科技有限公司 | Pixel circuit and driving method thereof, array substrate and display device |
| WO2015062298A1 (en) * | 2013-11-04 | 2015-05-07 | 京东方科技集团股份有限公司 | Oled pixel circuit and driving method thereof, and display device |
| US9589505B2 (en) | 2013-11-04 | 2017-03-07 | Boe Technology Group Co., Ltd. | OLED pixel circuit, driving method of the same, and display device |
| CN108520718A (en) * | 2018-04-18 | 2018-09-11 | 京东方科技集团股份有限公司 | A kind of pixel data compensation method of display device and device, display device |
| CN108520718B (en) * | 2018-04-18 | 2019-12-27 | 京东方科技集团股份有限公司 | Pixel data compensation method and device of display device and display device |
| CN111243504A (en) * | 2018-11-29 | 2020-06-05 | 昆山工研院新型平板显示技术中心有限公司 | Pixel driving circuit and display device |
| CN111243504B (en) * | 2018-11-29 | 2021-04-23 | 成都辰显光电有限公司 | Pixel driving circuit and display device |
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Granted publication date: 20130828 |
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