CN202711665U - Pixel circuit and organic light emitting display - Google Patents
Pixel circuit and organic light emitting display Download PDFInfo
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- CN202711665U CN202711665U CN2012203874117U CN201220387411U CN202711665U CN 202711665 U CN202711665 U CN 202711665U CN 2012203874117 U CN2012203874117 U CN 2012203874117U CN 201220387411 U CN201220387411 U CN 201220387411U CN 202711665 U CN202711665 U CN 202711665U
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- film transistor
- thin film
- tft
- light emitting
- driving thin
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Abstract
The utility model provides a pixel circuit and an organic light emitting display. The pixel circuit comprises a driving thin film transistor, a storage capacitor, a light emission control unit, a drive control unit and an organic light emitting diode, wherein the grid of the driving thin film transistor is connected with a first end of the storage capacitor, a source is connected with a first end of the light emission control unit, and a drain is connected with a first end of the drive control unit; a second end of the storage capacitor is connected with a first end of a first capacitor; a second end of the light emission control unit is connected with the grid of the driving thin film transistor, a third end is connected with the drain of the driving thin film transistor, a fourth end is grounded, and a control end is connected with a light emission control line; a second end of the drive control unit is connected with a cathode of the organic light emitting diode, and a third end is connected with the source of the driving thin film transistor, a fourth end is connected with a data line, and a control end is connected with a scanning line; a second end of the first capacitor is grounded; and the organic light emitting diode is connected with a high level output end of a driving power supply. According to the pixel circuit and the organic light emitting display, the problems of uneven brightness and brightness attenuation of the AMOLED panel can be solved.
Description
Technical field
The utility model relates to the organic light emitting display field, relates in particular to a kind of image element circuit and organic light emitting display.
Background technology
Existing pixel unit drive circuit as shown in Figure 1, this driving circuit comprises two transistors and an electric capacity, one of them transistor is switch transistor T 1, sweep signal Vscan by sweep trace output is controlled, purpose is in order to control the input of the data-signal Vdata on the data line Data, another transistor is driving tube T2, control OLED(Organic Light Emitting Diode, Organic Light-Emitting Diode) luminous; Cs is memory capacitance, is used for keeping the voltage that driving tube T2 is applied in non-scan period, and foregoing circuit is called as the 2T1C pixel unit drive circuit.
AMOLED is driven by the electric current that driving transistors produces when the state of saturation, because when inputting identical gray scale voltage, the different threshold voltage of described driving transistors can cause producing different drive currents, causes the inconsistency of electric current.And LTPS(Low Temperature Poly-silicon, the low temperature polycrystalline silicon technology) the non-constant of homogeneity of processing procedure upper threshold voltage Vth, Vth also has drift simultaneously, and therefore the brightness uniformity of traditional 2T1C pixel unit drive circuit is always very poor.
The utility model content
Fundamental purpose of the present utility model is to provide a kind of image element circuit and driving method and organic light emitting display, to improve the luminance uniformity of organic light emitting display.
In order to achieve the above object, the utility model provides a kind of image element circuit, comprise driving thin film transistor (TFT), luminous controling unit, driving control unit, memory capacitance, the first electric capacity and Organic Light Emitting Diode, wherein,
Described driving thin film transistor (TFT), grid is connected with the first end of described memory capacitance, and source electrode is connected with the first end of described luminous controling unit, and drain electrode is connected with the first end of described driving control unit;
The second end of described memory capacitance is connected with the first end of described the first electric capacity;
Described luminous controling unit, the second end is connected with the grid of described driving thin film transistor (TFT), and the 3rd end is connected with the drain electrode of described driving thin film transistor (TFT), the 4th end ground connection, control end is connected with the light emitting control line;
Described driving control unit, the second end is connected with the negative electrode of described Organic Light Emitting Diode, and the 3rd end is connected with the source electrode of described driving thin film transistor (TFT), and the 4th end is connected with data line, and control end is connected with sweep trace;
The second end ground connection of described the first electric capacity;
Described Organic Light Emitting Diode is connected with the high level output end of driving power.
During enforcement, described luminous controling unit comprises the first film transistor and the second thin film transistor (TFT);
Described the first film transistor, grid is connected with the light emitting control line, and source electrode is connected with the drain electrode of described driving thin film transistor (TFT), and drain electrode is connected with the grid of described driving thin film transistor (TFT);
Described the second thin film transistor (TFT), grid is connected with the light emitting control line, source ground, drain electrode is connected with the source electrode of described driving thin film transistor (TFT).
During enforcement, described driving control unit comprises the 3rd thin film transistor (TFT), the 4th thin film transistor (TFT) and the 5th thin film transistor (TFT);
Described the 3rd thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with data line, and drain electrode is connected with the second end of described memory capacitance;
Described the 4th thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with the negative electrode of described Organic Light Emitting Diode, and drain electrode is connected with the drain electrode of described driving thin film transistor (TFT);
Described the 5th thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with the second end of described memory capacitance, and drain electrode is connected with the source electrode of described driving thin film transistor (TFT).
During enforcement, described the first film transistor and described the 4th thin film transistor (TFT) are p-type TFT, and described the second thin film transistor (TFT), described the 3rd thin film transistor (TFT) and described the 5th thin film transistor (TFT) are N-shaped TFT.
The utility model also provides a kind of organic light emitting display, comprises above-mentioned image element circuit.
Compared with prior art, image element circuit described in the utility model and organic light emitting display, compensate the threshold voltage of the driving thin film transistor (TFT) of driving OLED by the gate source voltage of driving control unit control driving thin film transistor (TFT), thereby solution AMOLED panel luminance is inhomogeneous and the problem of brightness decay.
Description of drawings
Fig. 1 is the circuit diagram of existing 2T1C pixel unit drive circuit;
Fig. 2 is the circuit diagram of the first embodiment of image element circuit described in the utility model;
Fig. 3 is the circuit diagram of the second embodiment of image element circuit described in the utility model;
Fig. 4 is the first embodiment of image element circuit described in the utility model and the second embodiment signal timing diagram in phase one, subordinate phase, phase III;
Fig. 5 A is that the second embodiment of image element circuit described in the utility model is at the equivalent circuit diagram of very first time section;
Fig. 5 B is the equivalent circuit diagram of the second embodiment of image element circuit described in the utility model in the second time period;
Fig. 5 C is the equivalent circuit diagram of the second embodiment of image element circuit described in the utility model in the 3rd time period.
Embodiment
The utility model provides a kind of image element circuit and organic light emitting display, utilize diode connection (Diode Connection) and by the control store capacitor discharge so that drive the threshold voltage of driving thin film transistor (TFT) of the gate source voltage compensation driving OLED of thin film transistor (TFT), thereby the problem of the even brightness decay of solution oled panel brightness disproportionation.
As shown in Figure 2, the first embodiment of image element circuit described in the utility model comprises driving thin film transistor (TFT) DTFT, luminous controling unit 21, driving control unit 22, memory capacitance Cst, the first capacitor C 1 and Organic Light Emitting Diode OLED, wherein,
Described driving thin film transistor (TFT) DTFT, grid is connected with the first end of described memory capacitance Cst, and source electrode is connected with the first end of described luminous controling unit 21, and drain electrode is connected with the first end of described driving control unit 22;
The second end of described memory capacitance Cst is connected with the first end of described the first capacitor C 1;
Described luminous controling unit 21, the second ends are connected with the grid of described driving thin film transistor (TFT) DTFT, and the 3rd end is connected with the drain electrode of described driving thin film transistor (TFT) DTFT, the 4th end ground connection, and control end is connected with light emitting control line EM;
Described driving control unit 22, the second ends are connected with the negative electrode of described Organic Light Emitting Diode OLED, and the 3rd end is connected with the source electrode of described driving thin film transistor (TFT) DTFT, and the 4th end is connected with data line Data, and control end is connected with sweep trace SCAN;
The second end ground connection of described the first capacitor C 1;
Described Organic Light Emitting Diode OLED is connected with the high level output end VDD of driving power;
The high level output end output VDD of described driving power, described data line Data output data voltage Vdata, described light emitting control line EM output V
EM, described sweep trace SCAN output V
SCAN
The first embodiment of image element circuit described in the utility model is in when work,
At very first time section, i.e. pre-charging stage: V
SCAN, V
EMBe low level, being connected between the grid of the described driving thin film transistor (TFT) of described luminous controling unit 21 control conductings DTFT and the drain electrode, being connected between the drain electrode that described driving control unit 22 is controlled the described driving thin film transistor (TFT) of conductings DTFT and the described OLED; At this moment, described driving thin film transistor (TFT) DTFT enters state of saturation, is a diode in fact;
In the second time period, i.e. data write phase: V
SCANBe high level, V
EMBe low level, being connected between the drain electrode that 22 controls of described driving control unit disconnect described driving thin film transistor (TFT) DTFT and the described OLED, being connected between the second end of control conducting data line Data and described memory capacitance Cst, and being connected between the source electrode of the second end of control conducting described memory capacitance Cst and described driving thin film transistor (TFT) DTFT, data voltage Vdata writes, voltage difference between the first end of described memory capacitance Cst and the second end is Vth, this moment, the grid voltage of described driving thin film transistor (TFT) DTFT was Vdata+Vth, the source voltage of described driving thin film transistor (TFT) DTFT is Vdata, wherein, Vth is the threshold voltage of described driving thin film transistor (TFT) DTFT;
In the 3rd time period, i.e. OELD glow phase, V
SCANBe low level, V
EMBe high level, being connected between the drain electrode of the described driving thin film transistor (TFT) of described driving control unit 22 control conductings DTFT and the described OLED; The source electrode of the described driving thin film transistor (TFT) of described luminous controling unit 21 control conductings DTFT is connected with the ground end, this moment, the grid voltage of described driving thin film transistor (TFT) DTFT still was Vdata+Vth, the gate source voltage Vgs=Vdata+Vth of described driving thin film transistor (TFT) DTFT flows through electric current I=K (Vgs-Vth) of described driving thin film transistor (TFT) DTFT simultaneously
2=K (Vdata+Vth-Vth)
2=K(Vdata)
2
Wherein, K is the current coefficient of DTFT;
μ, C
OX, W, L be respectively the field-effect mobility of DTFT, gate insulation layer unit-area capacitance, channel width, length;
So eliminate the impact that drives the Vth of thin film transistor (TFT) DTFT, so just can improve the homogeneity of electric current, reached the even of brightness.
The second embodiment of image element circuit described in the utility model is based on the first embodiment of image element circuit described in the utility model.As shown in Figure 3, in the second embodiment of image element circuit described in the utility model, described luminous controling unit 21 comprises the first film transistor T 1 and the second thin film transistor (TFT) T2, described driving control unit 22 comprises the 3rd thin film transistor (TFT) T3, the 4th thin film transistor (TFT) T4 and the 5th thin film transistor (TFT) T5, wherein
Described the first film transistor T 1, grid is connected with light emitting control line EM, and source electrode is connected with the drain electrode of described driving thin film transistor (TFT) DTFT, and drain electrode is connected with the grid of described driving thin film transistor (TFT) DTFT;
Described the second thin film transistor (TFT) T2, grid is connected with light emitting control line EM, source ground, drain electrode is connected with the source electrode of described driving thin film transistor (TFT) DTFT;
Described the 3rd thin film transistor (TFT) T3, grid is connected with sweep trace SCAN, and source electrode is connected with data line Data, and drain electrode is connected with the second end of described memory capacitance Cst;
Described the 4th thin film transistor (TFT) T4, grid is connected with sweep trace SCAN, and source electrode is connected with the negative electrode of described Organic Light Emitting Diode OLED, and drain electrode is connected with the drain electrode of described driving thin film transistor (TFT) DTFT;
Described the 5th thin film transistor (TFT) T5, grid is connected with sweep trace SCAN, and source electrode is connected with the second end of described memory capacitance Cst, and drain electrode is connected with the source electrode of described driving thin film transistor (TFT) DTFT;
Wherein, described the first film transistor T 1 and described the 4th thin film transistor (TFT) T4 are p-type TFT, and described the second thin film transistor (TFT) T2, described the 3rd thin film transistor (TFT) T3 and described the 5th thin film transistor (TFT) T5 are N-shaped TFT.
Fig. 4 is the first embodiment of driving circuit described in the utility model and the second embodiment V in phase one, subordinate phase, phase III
SCAN, V
EM, Vdata sequential chart, in Fig. 4,1,2,3 respectively the indication be phase one, subordinate phase, phase III.
As shown in Figure 4, the second embodiment of image element circuit described in the utility model is in when work,
At very first time section, i.e. pre-charging stage: V
SCAN, V
EMBe low level, being connected between the grid of the described driving thin film transistor (TFT) of described the first film transistor T 1 control conducting DTFT and the drain electrode, being connected between the drain electrode that described the 4th thin film transistor (TFT) T4 controls the described driving thin film transistor (TFT) of conducting DTFT and the described OLED; At this moment, described driving thin film transistor (TFT) DTFT enters state of saturation, is a diode in fact;
In the second time period, i.e. data write phase: V
SCANBe high level, V
EMBe low level, being connected between the drain electrode that described the 4th thin film transistor (TFT) T4 control disconnects described driving thin film transistor (TFT) DTFT and the described OLED, being connected between the second end of described the 3rd thin film transistor (TFT) T3 control conducting data line Data and described memory capacitance Cst, being connected between the second end of the described memory capacitance Cst of described the 5th thin film transistor (TFT) T5 control conducting and the source electrode of described driving thin film transistor (TFT) DTFT, data voltage Vdata writes, voltage difference between the first end of described memory capacitance Cst and the second end is Vth, this moment, the grid voltage of described driving thin film transistor (TFT) DTFT was Vdata+Vth, the source voltage of described driving thin film transistor (TFT) DTFT is Vdata, wherein, Vth is the threshold voltage of described driving thin film transistor (TFT) DTFT;
In the 3rd time period, i.e. OELD glow phase, V
SCANBe low level, V
EMBe high level, being connected between the drain electrode of the described driving thin film transistor (TFT) of described the 4th thin film transistor (TFT) T4 control conducting DTFT and the described OLED; The source electrode of the described driving thin film transistor (TFT) of described the second thin film transistor (TFT) T2 control conducting DTFT is connected with the ground end, this moment, the grid voltage of described driving thin film transistor (TFT) DTFT still was Vdata+Vth, the gate source voltage Vgs=Vdata+Vth of described driving thin film transistor (TFT) DTFT flows through electric current I=K (Vgs-Vth) of described driving thin film transistor (TFT) DTFT simultaneously
2=K (Vdata+Vth-Vth)
2=K(Vdata)
2
Wherein, K is the current coefficient of DTFT;
μ, C
OX, W, L be respectively the field-effect mobility of DTFT, gate insulation layer unit-area capacitance, channel width, length;
So eliminate the impact that drives the Vth of thin film transistor (TFT) DTFT, so just can improve the homogeneity of electric current, reached the even of brightness.
Among the embodiment that the utility model can substitute, thin film transistor (TFT) can also be by triode, and metal-oxide-semiconductor (MOSFET, Metal-Oxide-Semiconductor Field-Effect-Transistor) etc. replaces, and can realize identical function.
Image element circuit described in the utility model adopts the 6T2C circuit by the Vth of compensation DTFT, so that the drive current I=K of DTFT * (Vgs-Vth)
2Or I=K (Vgs+Vth)
2Irrelevant with Vth, reach electric current consistent, improve homogeneity.
The utility model also provides a kind of organic light emitting display, comprises above-mentioned image element circuit.
Above explanation is just illustrative for the utility model; and it is nonrestrictive; those of ordinary skills understand; in the situation that does not break away from the spirit and scope that claims limit; can make many modifications, variation or equivalence, but all will fall in the protection domain of the present utility model.
Claims (5)
1. an image element circuit is characterized in that, comprise driving thin film transistor (TFT), luminous controling unit, driving control unit, memory capacitance, the first electric capacity and Organic Light Emitting Diode, wherein,
Described driving thin film transistor (TFT), grid is connected with the first end of described memory capacitance, and source electrode is connected with the first end of described luminous controling unit, and drain electrode is connected with the first end of described driving control unit;
The second end of described memory capacitance is connected with the first end of described the first electric capacity;
Described luminous controling unit, the second end is connected with the grid of described driving thin film transistor (TFT), and the 3rd end is connected with the drain electrode of described driving thin film transistor (TFT), the 4th end ground connection, control end is connected with the light emitting control line;
Described driving control unit, the second end is connected with the negative electrode of described Organic Light Emitting Diode, and the 3rd end is connected with the source electrode of described driving thin film transistor (TFT), and the 4th end is connected with data line, and control end is connected with sweep trace;
The second end ground connection of described the first electric capacity;
Described Organic Light Emitting Diode is connected with the high level output end of driving power.
2. image element circuit as claimed in claim 1 is characterized in that,
Described luminous controling unit comprises the first film transistor and the second thin film transistor (TFT);
Described the first film transistor, grid is connected with the light emitting control line, and source electrode is connected with the drain electrode of described driving thin film transistor (TFT), and drain electrode is connected with the grid of described driving thin film transistor (TFT);
Described the second thin film transistor (TFT), grid is connected with the light emitting control line, source ground, drain electrode is connected with the source electrode of described driving thin film transistor (TFT).
3. image element circuit as claimed in claim 2 is characterized in that,
Described driving control unit comprises the 3rd thin film transistor (TFT), the 4th thin film transistor (TFT) and the 5th thin film transistor (TFT);
Described the 3rd thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with data line, and drain electrode is connected with the second end of described memory capacitance;
Described the 4th thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with the negative electrode of described Organic Light Emitting Diode, and drain electrode is connected with the drain electrode of described driving thin film transistor (TFT);
Described the 5th thin film transistor (TFT), grid is connected with sweep trace, and source electrode is connected with the second end of described memory capacitance, and drain electrode is connected with the source electrode of described driving thin film transistor (TFT).
4. image element circuit as claimed in claim 3 is characterized in that,
Described the first film transistor and described the 4th thin film transistor (TFT) are p-type TFT, and described the second thin film transistor (TFT), described the 3rd thin film transistor (TFT) and described the 5th thin film transistor (TFT) are N-shaped TFT.
5. an organic light emitting display is characterized in that, comprises such as the described image element circuit of arbitrary claim in the claim 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012203874117U CN202711665U (en) | 2012-08-06 | 2012-08-06 | Pixel circuit and organic light emitting display |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012203874117U CN202711665U (en) | 2012-08-06 | 2012-08-06 | Pixel circuit and organic light emitting display |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202711665U true CN202711665U (en) | 2013-01-30 |
Family
ID=47591945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012203874117U Withdrawn - After Issue CN202711665U (en) | 2012-08-06 | 2012-08-06 | Pixel circuit and organic light emitting display |
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| CN (1) | CN202711665U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102789761A (en) * | 2012-08-06 | 2012-11-21 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and organic light emitting display |
-
2012
- 2012-08-06 CN CN2012203874117U patent/CN202711665U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102789761A (en) * | 2012-08-06 | 2012-11-21 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and organic light emitting display |
| CN102789761B (en) * | 2012-08-06 | 2014-12-10 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and organic light emitting display |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130130 Effective date of abandoning: 20141210 |
|
| RGAV | Abandon patent right to avoid regrant |