Research Article High Efficiency Driver for AMOLED with Compensationdownloads.hindawi.com/archive/2015/954783.pdf · 2019-07-31 · Research Article High Efficiency Driver for AMOLED

Research ArticleHigh Efficiency Driver for AMOLED with Compensation

Said Saad1 and Lotfi Hassine2

1Group of Electronics and Quantum Physics Laboratory of Advanced Materials and Quantum PhenomenaFaculty of Sciences of Tunis Tunis EL Manar University 2092 Tunis Tunisia2National Institute of Applied Sciences and Technology University of Carthage 1080 Tunis Tunisia

Correspondence should be addressed to Said Saad saadsaidbechirgmailcom

Received 27 May 2014 Accepted 10 January 2015

Academic Editor Liwen Sang

Copyright copy 2015 S Saad and L Hassine This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A new proposed compensation driver circuit of flat-panel display (FPD) based on organic light emitting diodes (OLEDs) and onpoly-crystalline silicon thin-film transistors (poly-Si TFTs) is presentedThis driver circuit is developed for an active-matrix organiclight-emitting-diode (AMOLED) display and its efficiency is verified compared with the conventional configuration with 2 TFTsAccording to results this circuit is suitable to achieve acceptable level for power consumption high contrast maximum gray levelsand better brightness And to show this a stable driving scheme is developed for circuit with much compensation such as againstthe data degradation the threshold voltage dispersions of TFT drive and suppression of TFT leakage current effect

1 Introduction

The new generation of display organic electronic displaybased on organic light emitting diodes (OLEDs) has estab-lished to eliminate the defects reported for the other tech-nologies (LCD and PLASMA) low contrast and high con-sumption [1 2] with speed conditions that may be unaccept-able for some displays of 3 dimensions due to addressing typeThis new technologymeets the needs of users in terms of purepicture quality and functioning level especially for mobiledevices it offers new possibilities previously unattainable asthe deposition on large surfaces or on flexible substratesbecause of low temperature of the OLED treatments [3 4]also the vision affects reality in terms of quality On the otherhand the current driven ofOLEDdevice can be provided by apassive matrix or active matrix backplane architecture [5] Inthe latter case the colour adjustment is determined by a com-mand based on thin film transistor (TFT) [1 5]This solutionis preferred especially when the size of the display increasedwhere we have technical problems [6] The backplane of theactive matrix is like a group of switchers or circuits whichcontrols the current intensity flowing through each OLEDpixel and does not let electricity only when this is necessaryThese circuitsrsquo designs are based on amorphous silicon (a-Si)

[7] polycrystalline silicon (poly-Si) [2] organic TFT (O-TFT) [8] and circuitsrsquo designs complementariness Accord-ing to the manufacturers several technologies backplanes interms of structure and level of fitness which are used foruniformity and stability sufficient for brightness which differin their driving speed power consumption area occupiedand the accuracy needed to set the current level have beenpresented In particular these driver circuits can be classifiedinto two programming modes in accordance with the datatype voltage-programming circuit and current-program-ming circuit [6] However for both types of circuits at thedriving scheme the variations in threshold voltage of TFTsdue to the change inmobility under the influence of operatingtime and under abnormal thermal conditions which canattain respectively 10 to 50 the data degradation andthe change in supply voltage the leakage current [9] and thespeed generate degradation and nonuniformity in brightnessover time in the pixel itself and in many cases there is afluctuation in brightness in the surrounding pixels Thesedisturbances add up over time and may be the cause of poorvision To avoid these problems the manufacturers are usingthese transistors with adequate compensation methods [5]Nevertheless high-quality displays low power consumptionand improvement of the nonuniform brightness and the effi-ciency of the driver circuits require several driving transistors

Hindawi Publishing CorporationAdvances in ElectronicsVolume 2015 Article ID 954783 5 pageshttpdxdoiorg1011552015954783

2 Advances in Electronics

Scan line

Data lineTFT2

OLED

TFT1

Vdd

Cstg

(a)

Scan line

Data lineTFT2

TFT6

TFT4

TFT5

TFT3

TFT1

OLED

Scan2line Cstg

Vdd

(b)

Figure 1 AMOLED (a) conventional pixel circuit and (b) proposed pixel circuit

per pixel to allow compensation for major technical prob-lems Specifically using compensation circuits based on poly-Si technology has been a considerable progress in providingstable and uniform brightness with great lifetime Also it isnot cost-effective in comparisonwith other TFT technologies(a-TFT and O-TFT) and it can provide constant current toOLED and excellent mobility compensation circuits reachedthe requirements of OLED driving current under minimumpower supply respecting the speed condition and also assistsin the direct integration of the driver circuit on the flexiblesubstrates [2 5ndash7 10] In this paper we privilege the use ofpoly-Si transistor for the proposed driver circuit And gener-ally we can say that the choice of one of these transistors isclosely related to the manufacture which has its own parame-ters and its driving schemes and the technology used tomakethe AMOLED screen

2 The Proposed Driver Pixel Circuit

As we have said before we have chosen the use of poly-Sifor the proposed driver circuit And to ensure high speed itwill be preferable to useN-type transistors rather than P-typeAlso for applications of high frequency it is better to use thoseof N-type instead of P-type For these reasons we chose usingan N-type transistor as a scan transistor And for applicationwe use enrichment MOSFET models thanks to the perfor-mances that they give especially under abnormal thermalconditions The proposed design is explained compared withthe conventional circuit based on 2-TFTs Figure 1(a) [6 8 11]

This last is established to depart from the approach of pas-sive matrix and to better enhance the performances of pixelwith one transistor where high current 119868OLED to achievethe desired brightness is required with nonuniform levelswhere the pixel is almost always active It contains anembedded memory119862stg and tow transistors TFT1 is used toselect a specific pixel and to transfer the data through the data

line The data make the loading of the storage capacitance119862stg during one period of operation when the scan line is inhigh state The current is injected to the organic diode whichemits light It is adjusted by the TFT2 the driver transistorand is expressed by [5]

119868OLED =119870TFT22times (119881GS-TFT2 minus 119881Th-TFT2)

2

(1)

where119870TFT2 is the transconductance factor of TFT2119881GS-TFT2is the voltage applied to the TFT2 gate-source terminal and119881Th-TFT2 is the threshold voltage of TFT2 The simulation forthe current delivered to theOLEDof this conventional circuitis presented in Figure 2 From the curve the maximum valueof 119868OLED is 3798 120583A This last value does not represent trulythe data voltage because the voltage level representing datahas dropped and this is due to the threshold voltage 119881Th-TFT1of TFT1 and the recovered voltage is 119881Data minus 119881Th-TFT1 Alsothis conventional configuration presents a variation in thethreshold voltage of TFT2 [6] and TFT1 All these problemslead to a nonuniform brightness during the display phase andso have a direct influence on the gray levels So wemust thinkabout compensation methods to avoid these problems

Firstly to well compensate the loss in data voltage we addanother transistor of P-type a restoration transistor TFT3Figure 1(b) With this transistor the charge stored in thecapacity is exactly the data voltage but the most importantissue is the size of this restoration transistor In reality it actsas capacitance and their limited size is directly related to theloading time of 119862stg with TFT1 and their internal capaci-tance 119862gb (gate-bulk capacitance) this is a very importantcondition for calculating their capacitance Therefore thistransistor provides a load current in capacitance 119862stg anddecreases the charging time to make it equal to the time ofloading capacitance 119862stg through TFT1 so it must reduce itsinternal resistance (119877sh drain source diffusion sheet resis-tance) resulting from an increase in their ratio119882TFT3119871TFT3

Advances in Electronics 3

10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)

ConventionalConventional with restoration transistor

Proposed driver

I OLE

D(120583

A)

Figure 2 OLED current during the display phase in conventionalconfiguration of 2 TFTs driver circuit with restoration transistorfinal model of proposed driver circuit

Subsequently we have two conditions that must be respectedwe increase119882119871 to reduce the resistance andwe increase119882times119871 to increase the internal capacitance 119862gb of this transistorThe optimal values that allow us to offset the data degradationare threshold voltage 119881Th-TFT3 = minus119881Th-TFT1 and 119882 = 4 times 119871In this condition the maximum current delivered to theOLED becomes 7 120583A see Figure 2 and therefore we havesuccessfully corrected the data degradation and increase thecurrent 119868OLED In addition despite the compensation of thedata degradation we have always the problem of thresholdvoltage variation of TFT2with increased energy consumptiondue to the presence of anther capacitance which is repre-sented by the transistor TFT3 So we seek amethod to resolvethese problems First to minimize power consumption theOLED is active only if necessary For this a new transistorof P-type TFT4 ordered by a new control line Scan2line isadded as shown Figure 1(b) this transistor does not leave thedriver circuit works only if that is necessary even if the 119881Datais already stored in the capacitance 119862stg Second to avoid theproblem of the threshold voltage variation of TFT2 we addanother transistor of P-type TFT5 Figure 1(b) The simula-tion gives an increase in the maximum current to 9 120583A seeFigure 2 This increase of 2 120583A is due in fact to the storage ofthe threshold voltage119881Th-TFT2 of TFT2 in the capacitance119862stgMoreover the presence of leakage current in theOLEDduringthe reset phase requires us to add another transistor to elim-inate it because this current becomes critical for the lifetimeof OLED so in screen over time where the screen colours willbecome darker if we exceed certain hours of operation andhas a direct effect on the contrast and on the stored chargein 119862stg [9] So it must be reducing leakage current To dothis we add another transistor P-type TFT6 to block theemission current through the OLED during the reset phase

Scan line

Data line

Initialization DisplayCompensation Disabling

(1) (2) (3) (4)

Scan2line

Figure 3 Timing scheme

Initialization

DisplayCompensation

DisablingTFT4 TFT4

TFT2TFT6

TFT2

TFT6

TFT4TFT4TFT5

TFT6 TFT6TFT2TFT2

OLED

OLEDOLED

OLED

Vdd

Vdd Vdd

Vdd

SS

GG

GG

DD

D D

S SVdata + VTh-TFT2 Vdata + VTh-TFT2

Vdata

Cstg Cstg

CstgCstg

Figure 4 Equivalent circuits in each step of operation of theproposed design

and ensure greater stability for the pixel Figure 1(b) There-fore the final proposed driver circuit is able to reduce theproblem of nonuniformity of brightness it has a large outputcurrent with faster response time it can block the currentcirculating in the OLED during the reset period where anincrease in contrast ratio is guaranteed and it reduces energyconsumption Also the OLED is placed between the drain ofTFT6 and the ground to cancel the transient characteristicsSo we can say that the proposed circuit pixel is suitablefor AMOLED screen but it requires more precision by theinsertion of the new control signal Scan2line

3 Driving Scheme

In the proposed design exposed in Figure 1(b) TFT1 TFT4TFT5 and TFT6 function as switches TFT3 is the restorationtransistor and TFT2 is the driving transistor it operates insaturation regime when it is in the passant state The timingor the driving scheme for this proposed driver is definedas shown in Figure 3 Figure 4 shows the operations stepswith the main compensations From these figures we find thefollowing

Initialization Phase of Data It is the activation phase Duringit the signals scan line and data line are in the high state theTFT1 and TFT3 are passers The capacitance 119862stg loads up aspecific value which is119876 = 119862 sdot119881Data But it must pay attentionto the threshold voltage of TFT1119881Th-TFT1 because the outputof this transistor is also 119881Data minus 119881Th-TFT1 so the presence ofTFT3 is verified because it enables making the correction


for the loss of 119881Data so during this phase the capacitance 119862stgloads to 119881Data as shown the relationship

119881stg = 119881Data minus 119881Th-TFT1 +1003816100381610038161003816119881Th-TFT3

1003816100381610038161003816 (2)

Compensation Phase of theThreshold Voltage of TFT2 Duringthis phase the signal Scan2line is in the high state TFT4 andTFT6 are blocked and data line is in the low state tomake theloading of the threshold voltage of TFT2 in the capacitance119862stg At this time the gate of TFT2 is connected with theirdrain through the transistor TFT5 where we have a diodetype connection and so the voltage across the capacity 119862stgbecomes 119881Data + 119881Th-TFT2 This technique allows cancellingthe threshold voltage variation when the TFT2 commandsOLED

Display Phase After the scan time of pixel and the step ofinitialization and compensation for the data voltages and forthe 119881Th-TFT2 the signal Scan2line becomes in the low stateDuring this period the TFT2 provided to the OLED thecurrent

119868OLED =119870

2times (119881GS-TFT2 minus 119881Th-TFT2)

2

=119870

2times (119881Data + 119881Th-TFT2 minus 119881Th-TFT2)

2

=119870

2119881Data2

(3)

As indicated in this expression the drain current of TFT2is independent of the threshold voltage of TFT2 and is onlyaffected by 119881Data therefore uniform brightness of the imagecan be defined according to the desired gray levels

Disabling Phase This is the nonoperation phase of the pixelIt is applied if we want to avoid the operation of the pixel It isobtained by forcing the signal Scan2line to be in a high stateeven in the case where we have a charge stored in the capac-itance 119862stg This charge remains constant until the next resetphase

4 Performances and Discussion

In the proposed design of the driver circuit the OLEDcurrent depends only on data Also there is an increase in thecontrast ratio by inserting the transistor TFT6 as the OLED isdisconnected from another part of the circuit during theinitialization and compensation phase so it does not emitlight during the addressing phase and therefore a perfectblack colour is displayed In the other hand the circuit is ther-mally stressed and its operating temperature increases overtime And to assess how this circuit operates under abnormalthermal conditions we also perform the simulations atdifferent temperaturesThe results are shown in Figure 5 at 27and 100∘CAs a result there is a slight variation in 119868OLED underthermal conditions due to the changes in mobility in thedriving transistor TFT2 In addition a reduction in energyconsumption is accomplished by inserting the transistorTFT4 And generally the driver circuit behaves as amultitudeof capacities that need to load and unload In general we havethe two energy contributions static and dynamic However

10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)

27∘C100∘C

I OLE

D(120583

A)

Figure 5 Influence of abnormal thermal condition on 119868OLED

the static consumption is almost zero so we need to only con-sider the dynamic power consumption given by the followingformula [6]

119875dynamique =1

2times 1205720rarr1times 119862119871times 119881dd2times 119891 (4)

where 119862119871

is the equivalent capacitance of loading andunloading in the driver circuit 119881dd is the supply voltage and119891 is the operating frequency of the driver circuit position byScan2line The 120572

0rarr1is the probability of having consump-

tion during one clock cycle this parameter is determinedaccording to the driving scheme used and its value is between0 and 1 This expression of power explains the continuingefforts of the circuit designers to reduce the size of transistorswhich reduces the value of parasitic capacities and reducethe supply voltage in order to increase the working frequencyof circuits For the proposed pixel circuit we take the values120572 = 033 and119862

119871= 1 pF Hence 119875dynamique = 20625 sdot 10

minus6W Ifwe calculate this consumption for a screenwith the resolution176times 220 we obtain 119875 = 7968mW And when a comparisonis made between AMOLED screen of 22 inch with resolution176 times 220 that is presented in [1] and AMOLED screen withthe same resolution using the proposed circuit we note thatthis consumption has decreased by about 60 Furthermorewe must note that this consumption is calculated withoutresistive and capacitive couplings for a total screen so tomakeclear consumption we must take into account these capaci-tances We must also take into account the overlap capaci-tances of TFTs (119862GS 119862GD and 119862GB) Also these capacitanceshave a direct influence on the loading of the data voltage(119862Dataline) in the capacitance 119862stg and on the speed of circuit(119862Scanline and 119877Scanline) for AMOLED screen But generallythese values depend on the manufacturing process of TFTsand we can neglect them Moreover when we talk about graylevels the parameter which directly affects these levels is thesize of the capacitance119862stg becausewith a very precise adjust-ment we can oblige the capacitance not to make an error that


exceeds the voltage necessary to pass from one gray level toanother level

5 Conclusion

In this work a new compensation driver circuit based on thetechnology TFT poly-Si as a support of the organic matrixthanks to its speed and its thermal stability is proposedwith its driving scheme consisting of 6 transistors TFTs andhaving three input lines (data line and scan line plus one addi-tional control signal Scan2line) plus one storage capacitanceBy results of circuit tests it is found that the proposed circuitcan be successfully operated under optimal timing schemeit offers a stable output current of high value while keepinga response time relatively fast compatible with the require-ments of AMOLEDdisplays underminimal power consump-tion and abnormal thermal conditions We have shown forthis proposed circuit a driving scheme based on restorationtechnique for the data degradation and compensation ofthe threshold voltage variation of TFT2 driver by using themethod of loading this voltage in the capacitance 119862stg Onthe other hand to reduce energy consumption increase thecontrast ratio and suppress TFT leakage effect we haveintroduced two other transistors with additional signal line toprevent the leakage current and to make this pixel operate asneeded This proposed circuit is compared with the conven-tional circuit of 2 TFTs and we can simply say that it is verysuitable for contrast consumption speed and stability ofbrightness

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by Laboratory of AdvancedMateri-als and Quantum Phenomena Faculty of Sciences of TunisTunis EL Manar University and funded by the Ministry ofHigher Education and Scientific Research Tunisia

References

[1] J Y Lee J H Kwon and H K Chung ldquoHigh efficiency andlow power consumption in active matrix organic light emittingdiodesrdquo Organic Electronics vol 4 no 2-3 pp 143ndash148 2003

[2] K Park J-H Jeon Y Kim et al ldquoA poly-Si AMOLED displaywith high uniformityrdquo Solid-State Electronics vol 52 no 11 pp1691ndash1693 2008

[3] C-C Wu C-W Chen C-L Lin and C-J Yang ldquoAdvancedorganic light-emitting devices for enhancing display perfor-mancesrdquo IEEEOSA Journal of Display Technology vol 1 no 2pp 248ndash266 2005

[4] G-F Wang X-M Tao and R-X Wang ldquoFabrication andcharacterization of OLEDs using PEDOTPSS and MWCNTnanocompositesrdquo Composites Science and Technology vol 68no 14 pp 2837ndash2841 2008

[5] B-T Chen Y-H Tai Y-J Kuo C-C Tsai and H-C ChengldquoNew pixel circuits for driving active matrix organic light emit-ting diodesrdquo Solid-State Electronics vol 50 no 2 pp 272ndash2752006

[6] G Palumbo and M Pennisi ldquoAMOLED pixel driver circuitsbased on poly-Si TFTs a comparisonrdquo Integration the VLSIJournal vol 41 no 3 pp 439ndash446 2008

[7] M H Kang J H Hur Y D Nam E H Lee S H Kim andJ Jang ldquoAn optical feedback compensation circuit with a-SiHthin-film transistors for active matrix organic light emittingdiodesrdquo Journal of Non-Crystalline Solids vol 354 no 19-25 pp2523ndash2528 2008

[8] W F Aerts S Verlaak and P Heremans ldquoDesign of an organicpixel addressing circuit for an active-matrix OLED displayrdquoIEEE Transactions on Electron Devices vol 49 no 12 pp 2124ndash2130 2002

[9] J-H Lee H-S Park J-H Jeon andM-KHan ldquoSuppression ofTFT leakage current effect on active matrix displays by employ-ing a new circular switchrdquo Solid-State Electronics vol 52 no 3pp 467ndash472 2008

[10] Y-J Yun B-G Jun Y-K Kim J-W Lee andY-M Lee ldquoDesignof system-on-glass for poly-Si TFT OLEDs using mixed-signalssimulationrdquo Displays vol 30 no 1 pp 17ndash22 2009

[11] J O LeeH-H YangWW Jang and J-B Yoon ldquoAnewmethodof driving an AMOLEDwithMEMS switchesrdquo in Proceedings ofthe IEEE 21st International Conference onMicro ElectroMechan-ical Systems (MEMS 08) pp 132ndash135 Tucson Ariz USAJanuary 2008

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DistributedSensor Networks



Scan line

Data lineTFT2

OLED

TFT1

Vdd

Cstg

(a)

Scan line

Data lineTFT2

TFT6

TFT4

TFT5

TFT3

TFT1

OLED

Scan2line Cstg

Vdd

(b)

Figure 1 AMOLED (a) conventional pixel circuit and (b) proposed pixel circuit

per pixel to allow compensation for major technical prob-lems Specifically using compensation circuits based on poly-Si technology has been a considerable progress in providingstable and uniform brightness with great lifetime Also it isnot cost-effective in comparisonwith other TFT technologies(a-TFT and O-TFT) and it can provide constant current toOLED and excellent mobility compensation circuits reachedthe requirements of OLED driving current under minimumpower supply respecting the speed condition and also assistsin the direct integration of the driver circuit on the flexiblesubstrates [2 5ndash7 10] In this paper we privilege the use ofpoly-Si transistor for the proposed driver circuit And gener-ally we can say that the choice of one of these transistors isclosely related to the manufacture which has its own parame-ters and its driving schemes and the technology used tomakethe AMOLED screen

2 The Proposed Driver Pixel Circuit

As we have said before we have chosen the use of poly-Sifor the proposed driver circuit And to ensure high speed itwill be preferable to useN-type transistors rather than P-typeAlso for applications of high frequency it is better to use thoseof N-type instead of P-type For these reasons we chose usingan N-type transistor as a scan transistor And for applicationwe use enrichment MOSFET models thanks to the perfor-mances that they give especially under abnormal thermalconditions The proposed design is explained compared withthe conventional circuit based on 2-TFTs Figure 1(a) [6 8 11]

This last is established to depart from the approach of pas-sive matrix and to better enhance the performances of pixelwith one transistor where high current 119868OLED to achievethe desired brightness is required with nonuniform levelswhere the pixel is almost always active It contains anembedded memory119862stg and tow transistors TFT1 is used toselect a specific pixel and to transfer the data through the data

line The data make the loading of the storage capacitance119862stg during one period of operation when the scan line is inhigh state The current is injected to the organic diode whichemits light It is adjusted by the TFT2 the driver transistorand is expressed by [5]

119868OLED =119870TFT22times (119881GS-TFT2 minus 119881Th-TFT2)

2

(1)

where119870TFT2 is the transconductance factor of TFT2119881GS-TFT2is the voltage applied to the TFT2 gate-source terminal and119881Th-TFT2 is the threshold voltage of TFT2 The simulation forthe current delivered to theOLEDof this conventional circuitis presented in Figure 2 From the curve the maximum valueof 119868OLED is 3798 120583A This last value does not represent trulythe data voltage because the voltage level representing datahas dropped and this is due to the threshold voltage 119881Th-TFT1of TFT1 and the recovered voltage is 119881Data minus 119881Th-TFT1 Alsothis conventional configuration presents a variation in thethreshold voltage of TFT2 [6] and TFT1 All these problemslead to a nonuniform brightness during the display phase andso have a direct influence on the gray levels So wemust thinkabout compensation methods to avoid these problems

Firstly to well compensate the loss in data voltage we addanother transistor of P-type a restoration transistor TFT3Figure 1(b) With this transistor the charge stored in thecapacity is exactly the data voltage but the most importantissue is the size of this restoration transistor In reality it actsas capacitance and their limited size is directly related to theloading time of 119862stg with TFT1 and their internal capaci-tance 119862gb (gate-bulk capacitance) this is a very importantcondition for calculating their capacitance Therefore thistransistor provides a load current in capacitance 119862stg anddecreases the charging time to make it equal to the time ofloading capacitance 119862stg through TFT1 so it must reduce itsinternal resistance (119877sh drain source diffusion sheet resis-tance) resulting from an increase in their ratio119882TFT3119871TFT3


10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)


Proposed driver

I OLE

D(120583

A)



Scan line

Data line


(1) (2) (3) (4)

Scan2line


Initialization

DisplayCompensation

DisablingTFT4 TFT4

TFT2TFT6

TFT2

TFT6

TFT4TFT4TFT5

TFT6 TFT6TFT2TFT2

OLED

OLEDOLED

OLED

Vdd

Vdd Vdd

Vdd

SS

GG

GG

DD

D D


Vdata

Cstg Cstg

CstgCstg



3 Driving Scheme






1003816100381610038161003816 (2)



119868OLED =119870


2

=119870


2

=119870

2119881Data2

(3)





10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)

27∘C100∘C

I OLE

D(120583

A)



119875dynamique =1


where 119862119871








5 Conclusion




Acknowledgments


References














RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)


Proposed driver

I OLE

D(120583

A)



Scan line

Data line


(1) (2) (3) (4)

Scan2line


Initialization

DisplayCompensation

DisablingTFT4 TFT4

TFT2TFT6

TFT2

TFT6

TFT4TFT4TFT5

TFT6 TFT6TFT2TFT2

OLED

OLEDOLED

OLED

Vdd

Vdd Vdd

Vdd

SS

GG

GG

DD

D D


Vdata

Cstg Cstg

CstgCstg



3 Driving Scheme






1003816100381610038161003816 (2)



119868OLED =119870


2

=119870


2

=119870

2119881Data2

(3)





10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)

27∘C100∘C

I OLE

D(120583

A)



119875dynamique =1


where 119862119871








5 Conclusion




Acknowledgments


References














RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












1003816100381610038161003816 (2)



119868OLED =119870


2

=119870


2

=119870

2119881Data2

(3)





10

8

6

4

2

0

minus2

minus44 42 44 46 48 5

Time (120583s)

27∘C100∘C

I OLE

D(120583

A)



119875dynamique =1


where 119862119871








5 Conclusion




Acknowledgments


References














RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











5 Conclusion




Acknowledgments


References














RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article High Efficiency Driver for AMOLED with Compensationdownloads.hindawi.com/archive/2015/954783.pdf · 2019-07-31 · Research Article High Efficiency Driver for AMOLED