CN1190765C - Current display drive circuit by field - Google Patents
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- CN1190765C CN1190765C CNB031050794A CN03105079A CN1190765C CN 1190765 C CN1190765 C CN 1190765C CN B031050794 A CNB031050794 A CN B031050794A CN 03105079 A CN03105079 A CN 03105079A CN 1190765 C CN1190765 C CN 1190765C
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Abstract
The present invention relates to a current subfield display drive circuit which can be applied to organic light emitting diode (OLED) display screens. The present invention comprises a reference current unit circuit part which is controlled by subfield change signals, a current input circuit part and a current output circuit part capable of generating multi-circuit equal current. A display cycle is divided into n subfields with equal time, and the current which is output to an OLED display screen by each subfield is respectively 1, 2, 4,..., 2<n-1> times of unit current. The display with total 2<n> grey levels is realized by utilizing the luminous performance of OLEDs and the linear relationship of the current. The present invention can achieve precise display with high grey levels without additional circuits. The current subfield display drive circuit of the present invention can be applied to passive or active matrix OLED displays of various types and various specifications in the field of information display, and is suitable for industrialized application.
Description
Affiliated technical field
The present invention relates to display driver circuit, especially a kind of electric current another arena display driver circuit that can be applicable to Organic Light Emitting Diode (OLED) display screen.
Background technology
Organic Light Emitting Diode (OLED) show and to be in the news first since 1987 (C.W.Tang and S.A.Vanslyke,＜Appl.Phys.Lett. 〉,
51, p539,1987) since, develop very rapidly, be that international information shows the research field that association is of greatest concern in recent years.Advantages such as the wide visual angle of OLED, fast response, technology are simple, active illuminating make it more to be applicable to just flourish personal digital assistant (PDA), palm PC, e-book and mobile communication small-medium size applications such as (as mobile phones) than LCD; Thin film transistor (TFT) (TFT) that makes with amorphous silicon or polysilicon combines, to be expected to active matrix OLED (AM-OLED) (the Mike Hack that formation can be suitable with thin film transistor (AM-LCD), J.J.Brown, J.K.Mahon et al., Performance of High Efficiency AMOLED Displays, IDMC 2000:435-439), in can strive all over the world with one on the extensive size.These characteristics make OLED be expected to become the main product of flat pannel display of future generation as current LCD.Therefore, international renowned companies such as Kodak, Sanyo, Dupont, Pioneer, Philips and Toshiba all fall over each other to carry out the research and development of OLED display technique.
OLED can be divided into passive matrix (PM-OLED) and active matrix (AM-OLED) two big classes.Device quality performance monochromatic, polychrome PM-OLED can satisfy commercial demand, and companies such as Pioneer have the industrialization plan.At present, the research of PM-OLED focuses on panchromaticization, industrialization technology, expands its application aspect the information demonstration.OLED to be put in the practical application and go, the driving and the control circuit that are complementary just must be arranged, because the display quality of OLED screen is not only relevant with the performance of itself with the life-span, and closely bound up with factors such as drive waveforms, patterns, be one of its key issue that can become flat-panel monitor of future generation (FPD) main product.PM-OLED be applicable to low cost, on a small scale, the demonstration of low quantity of information, and AM-OLED is applicable to the demonstration of high resolving power, large tracts of land, full color.The type of drive of OLED can be divided into the voltage signal driving and current signal drives.And use current signal can avoid comprising the device property difference of OLED and TFT and the influence of fluctuating effectively, can also avoid the influence of crosstalking (AComparison of Pixel Circuits for Active Matrix Polymer/Organic LED Displays because of supply voltage transmission pressure drop generation, D.Fish, N.Young, M.Childs, SID 02 DIGEST, pp.968-971).
Shown in the Figure of description 8 is typical passive matrix OLED, and all OLED 83 are common cathodes.Voltage or current signal are applied on the alignment 81, by applying a gating (low level) signal on horizontal scanning line 82, make the OLED that is positioned at this row can conducting luminous.Fig. 9 is the active matrix OLED that typical voltage signal drives, and its OLED 96 is common cathodes.By on horizontal scanning line 91, applying high level, make gate tube 93 conductings, at this moment the voltage signal on the column data line 92 is connected to the grid of driving tube 94 by gate tube 93, simultaneously with memory capacitance 95 chargings.After the driving tube conducting, be subjected to the electric currents of the different sizes of control output of its gate source voltage, make the OLED pixel luminous and show different gray levels.Figure 10 is the active matrix OLED that a kind of current signal drives, and its OLED 108 is common anodes.By on horizontal scanning line 101, applying low level, make gate tube 103 and switching tube 104 conductings, and switching tube 105 ends.At this moment the current signal on the column data line 102 is connected to the drain electrode of driving tube 106 by gate tube 103, by switching tube 104 memory capacitance 107 is charged simultaneously, after the driving tube conducting, the self-adjusting process of the voltage that electric current by flowing through driving tube 106 drain electrode and memory capacitance 107 produce at the driving tube grid, driving tube 106 are finally set up the electric current that equates with electric current on the column data line 102.When applying high level on the horizontal scanning line, gate tube 103 and switching tube 104 end, switching tube 105 conductings, and driving tube is subjected to the control output and onesize just now electric current of its gate source voltage, makes the OLED pixel luminous.The size of current of driving tube 106 outputs is only relevant with the size of current on the column data line 102, by adjusting this electric current, can make the electric current of the different sizes of driving tube 106 outputs, and make OLED show different gray levels.
Fig. 7 is the system diagram of OLED display screen and driving circuit thereof.Active/passive matrix OLED display screen 74 can be made up of Fig. 8, Fig. 9 or OLED matrix shown in Figure 10.Line-scanning drive circuit 71 is responsible for horizontal scanning line 81,91, the 101 output gating signals on display screen, each row of gating successively.Column data shift register 72 is responsible for receiving the data line signal from the outside in a line period, and it is latched the luminous and gray scale that is used to control OLED.Column signal driving circuit 73 is subjected to the control of column data shift register 72, and the voltage or the current signals of the different sizes of output on each the bar column signal line 82,92,102 on the display screen make OLED luminous and show different gray levels.
Passive matrix OLED shows, to have on small-medium size shows the ability that can compete mutually with STN LCD, and it is most important that gray scale shows.Existing report is to adopt " width modulation " pattern to realize display gray scale, its problem is that gray level is difficult to improve and complicated (the Satoshi Miyaguchi of driving circuit, Shinichi Ishizuka, Takeo Wakimoto, Organic LED full-color passive-matrix display, Journal of the SID 7/3,1999:221-225).
Aspect active Driving technique, in the world Qi Bu time not remote, they use existing TFT-LCD existing basis and with the combining closely of organic light emission technology, speed of development is suitable fast.1996 just by U.S. Planna company, Kodark company, four families such as Sarnoff research institute and Princeton university propose the research of TFT-OLED and attempt, SID in 2000 can go up and just see the example that 5.5 inches polysilicon AM-OLED succeed in developing, calendar year 2001 is then seen report (the Tatsuya Sasaoka of 13 feet LTPSTFT-OLED, Mitunobu Sekiya, Akiya Yumoto et, al., " Late-News paper:A13.0-inch AM-OLED Display with Top Emitting Structure andAdaptive Current Mode Programmed Pixel Circuit (TAC); " SID 01 DIGEST, p.384), development is rapidly soon.But active matrix OLED also exists some key issues to need to solve, luminous problem of inconsistency between pixel during for example large tracts of land shows, and the frequency of operation of high resolution display driving circuit is crossed problems such as height.Utilize current drives and another arena to show (Mayumi Mizukami, Kazutaka Inukai, Hirokazu Yamagata etal., 6-Bit Digital VGA OLED, SID 00 GIGEST:912-915) combination, can well solve the problem of display consistency, and the drive pattern of electric current another arena can avoid drive circuit works under too high frequency.
Develop the OLED cause of China oneself, must take to have " great-leap-forward " development model of self-IP kernel, we propose a kind of electric current and divide field mode to obtain gray level for this reason, and this is a kind of accurate digital drive mode, and its obtainable gray level of institute is relevant with sub-number of fields and current ratio.
Summary of the invention
The objective of the invention is to propose a kind of electric current another arena display driver circuit.The present invention is by the self-adjusting of the output current of each son field, can not need adjunct circuit just can reach accurate and higher gray level expressing, can realize that digitizing shows simultaneously.The present invention has simplified sequential and circuit structure simultaneously, and can realize higher consistance.Therefore, the present invention can realize consistance preferably and the higher gray level display that OLED shows with circuit of simplifying and sequential.Electric current of the present invention another arena display driver circuit can be applied in the passive or active matrix OLED display of various forms in the field of information display and scale.
The present invention mainly comprises a reference current element circuit, one or more current input circuits, and one with last current output unit circuit; The main display cycle is divided into n son field that equates, each son drive current for the output of OLED display screen is respectively 1,2,4 ..., 2
N-1Times unitary current utilizes OLED electric current and luminous linear relationship, can realize 2
nThe demonstration of individual gray level, each son field of described electric current another arena display driver circuit is OLED display screen output multichannel, accurate and proportional drive current.
Described electric current another arena display driver circuit mainly included a reference/input current unit and one with last current output unit, and this reference/input current unit comprises:
One reference current transistor, its source ground, its grid connects a reference voltage signal, and its drain current is a unitary current; One current input transistor, its source electrode connects power supply, and its drain electrode connects the drain electrode of this reference current transistor, and its grid links to each other with its drain electrode;
Each current output unit comprises:
One first electric current output transistor, its breadth length ratio equals the breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the transistorized grid of this electric current input current; One first a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects first son control voltage signal, and its drain electrode connects the output terminal of this current output unit; One second electric current output transistor, its breadth length ratio equal 2 times of breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor; One second a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects second son control voltage signal, and its drain electrode connects the output terminal of this current output unit; One the 3rd electric current output transistor, its breadth length ratio equal 4 times of breadth length ratio of reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor; One the 3rd a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the 3rd a son control voltage signal, and its drain electrode connects the output terminal of this current output unit; One the 4th electric current output transistor, its breadth length ratio equal 8 times of breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor; One the 4th a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the 4th a son control voltage signal, and its drain electrode connects the output terminal of this current output unit; One row switching transistor, its source electrode connects the output terminal of this current output unit, and its grid connects the column data signal, and it leaks the output terminal of level as these row;
Described electric current another arena display driver circuit can realize that 16 grades of gray scales show at 4 sons, 4 proportional drive currents of output; Described reference current transistor is a nmos pass transistor; Described current input transistor, electric current output transistor, a son gauge tap transistor and row switching transistor are the PMOS transistor.
Described reference current element circuit can realize 1,2,4 ..., 2
N-1Doubly to the electric current output of unitary current, it mainly comprises n sub-field current source, and each sub-field current source comprises:
One sub-field current source transistor, its source ground, its grid connects reference voltage signal;
One sub-field switch transistor, its source electrode connects the leakage level of this sub-field current source transistor, and its grid connects a son control signal, and it leaks the output terminal that level connects this reference current element circuit.
The sub-field current source transistor of described reference current element circuit and this sub-field switch transistor are nmos pass transistor; 1,2,4 of the breadth length ratio unit of the being followed successively by breadth length ratio of the 1st to n sub-field current source transistor of described reference current element circuit ..., 2
N-1Doubly; The the 1st to n the transistorized grid of sub-field switch connects the 1st to a n control signal successively.
The present invention mainly comprises: a described reference current element circuit; One current input transistor, its source electrode connects power supply, and its grid links to each other with its drain electrode, and its drain electrode connects the output terminal of this reference current element circuit;
One with last current output unit, and each current output unit comprises: an electric current output transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor; One row switching transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the column data signal, and its drain electrode is as the output terminal of these row; Described current input transistor, electric current output transistor and row switching transistor are the PMOS transistor.
The present invention includes described reference current element circuit and one with last electric current I/O unit, each electric current I/O unit comprises:
One electric current input/output transistors, its source electrode connects power supply;
One memory capacitance, one termination power, the grid of its other this electric current input/output transistors of a termination;
One first switching transistor, its drain electrode connects the grid of this electric current input/output transistors, and its source electrode connects the drain electrode of this electric current input/output transistors, and its grid connects the one scan control signal;
One second switch transistor, its drain electrode connects the drain electrode of this electric current input/output transistors, and its source electrode connects the output terminal of this reference current unit, and its grid connects the grid of this first switching transistor; One electric current output switching transistor, its source electrode connects the drain electrode of this electric current input/output transistors, and its grid connects the grid of this first switching transistor; One row switching transistor, its source electrode connects the drain electrode of this electric current input/output transistors, and its grid connects a column data signal, and its drain electrode is as the output terminal of these row; Described electric current input/output transistors, electric current output switching transistor and this row switching transistor are the PMOS transistor, and described first switching transistor and described second switch transistor are nmos pass transistor.
Described electric current another arena display driver circuit, first the son the time, first the son gauge tap transistor turns, second and third, four the son gauge tap transistor end, when the conducting of row switching transistor, current output unit is exported 1 times to the electric current of unitary current; In the time of second sub, second a son gauge tap transistor turns, first and third, four a son gauge tap transistor end, and when the conducting of row switching transistor, current output unit is exported 2 times to the electric current of unitary current; When the 3rd son, the 3rd a son gauge tap transistor turns, first and second, four a son gauge tap transistor end, when the conducting of row switching transistor, 4 times of current output unit outputs are to the electric current of unitary current; In the time of the 4th sub, the 4th a son gauge tap transistor turns, first, second and third son gauge tap transistor ends, and when the conducting of row switching transistor, current output unit is exported 8 times to the electric current of unitary current.
Described reference current element circuit, corresponding the 1st to n son field has only the 1st to n gauge tap conducting respectively, and all the other son field gauge tap are ended, and reference current circuit exports 1,2,4 successively ..., 2
N-1Doubly to the electric current of unitary current.
Described electric current another arena display driver circuit, under the effect of a son control signal, the 1st to a n son gauge tap conducting successively, when this row switch conduction, this current output unit is listed as output 1,2,4 to this ..., 2
N-1Doubly to the electric current of unitary current.
Described electric current another arena display driver circuit, sweep signal on this electric current I/O unit is 1, this first switching transistor and the equal conducting of this second switch transistor, this electric current output switching transistor ends simultaneously, this electric current input/output transistors receives the electric current of this reference current element circuit output, simultaneously with the correspondent voltage signal storage on memory capacitance; When the sweep signal on this electric current I/O unit is 0, this first switching transistor and this second switch transistor all end, this electric current output switching transistor conducting, if this row switching transistor conducting, this electric current input/output transistors continues the corresponding steady current of output under the voltage effect on this memory capacitance.
Electric current of the present invention another arena display driver circuit is the passive of a kind of function admirable, Nover practical or active matrix organic light-emitting diode display drive circuit.Different gray levels then can show for simple 4 another arenaes by the incompatible realization of different set of currents, by the output of video data at a different sons control reference current, just can express 16 gray levels of 0-15.Be nonlinear relationship because OLED is luminous and its electric current is linear with voltage, so adopt electric current to replace driven can realize higher gray consistency and degree of accuracy.And to expand this circuit to realize higher gray level, and need not increase the scale of driving circuit, get final product with corresponding reference current and only need increase sub-number of fields order simply.
Electric current of the present invention another arena display driver circuit is another arena uniformly-spaced, has avoided too high frequency of operation; And the electric current that uses into ratio realizes that in the combination of different sons gray scale represents, each row only needs an electric current output transistor and corresponding row switching transistor to drive, D/A converting circuit, counting circuit or comparator circuit in other drive patterns have been omitted, simplified circuit complexity, so cost reduces greatly.
The present invention can realize consistance preferably and the higher gray level display that OLED shows with circuit of simplifying and sequential, thereby is better than existing other driving circuits, and can realize that digitizing shows.Contrast existing various driving circuit, the present invention has simplified sequential and circuit structure simultaneously, and can realize than higher consistance.
The present invention no matter purpose, means is all different with existing Driving technique with effect, is a breakthrough of Organic Light Emitting Diode display driver circuit, and has an invention that is applicable to that information display industry industrial applications is worth really.In addition, the present invention has the function of improvement and raising.The present invention can be applied to and comprise in PDA, palm PC, e-book and mobile communication (as mobile phone) and the various forms of organic light emitting diode display such as laptop computer displays and high-definition television.
Description of drawings
Fig. 1 is the electric current another arena display driver circuit that comprises a current output unit.
Fig. 2 is a kind of reference current element circuit of electric current of the present invention another arena display driver circuit.
Fig. 3 is the electric current another arena display driver circuit that comprises a current output unit.
Fig. 4 is the electric current another arena display driver circuit that comprises a current output unit.
Fig. 5 is that the current time of electric current of the present invention another arena display driver circuit concerns synoptic diagram.
Fig. 6 is sequential and the electric current distribution synoptic diagram that electric current of the present invention another arena display driver circuit is used for passive matrix and active matrix OLED display screen.
Fig. 7 be as a reference organic light-emitting diode (OLED) display screen and the system construction synoptic diagram of driving circuit.
Fig. 8 is the synoptic diagram of passive matrix OLED display screen as a reference.
Fig. 9 is the synoptic diagram of the active matrix OLED display screen of a kind of voltage signal driving as a reference.
Figure 10 is the synoptic diagram of the active matrix OLED display screen of a kind of current signal driving as a reference.
Embodiment
The present invention is described in detail as follows in conjunction with the accompanying drawings:
Fig. 1 shows a special case of the present invention that can realize 16 grades of gray scales.It mainly includes a reference/input current unit 11 and a plurality of current output unit 12.This reference/input current unit 11 comprises, a NMOS reference current transistor M1 and a PMOS current input transistor M2, and this transistor M1 source ground, its grid meets reference voltage signal Vref, and its drain current is a unitary current; This transistor M2 source electrode meets power supply Vdd, and its drain electrode connects the drain electrode of reference current transistor M1, and its grid links to each other with its drain electrode.Each current output unit 12 comprises, one first electric current output PMOS transistor MO1, its breadth length ratio equals the breadth length ratio of reference current transistor M1, its source electrode meets power supply Vdd, its grid connects the grid of this current input transistor M2, one first a son gauge tap PMOS transistor MS1, and its source electrode connects the drain electrode of this electric current output transistor MO1, its grid meets first son control voltage signal VSF1, and its drain electrode meets the output terminal Iout of current output unit; One second electric current output PMOS transistor MO2, its breadth length ratio equals 2 times of breadth length ratio of transistor M1, its source electrode meets power supply Vdd, its grid connects the grid of transistor M2, one second a son gauge tap PMOS transistor MS2, its source electrode connects the drain electrode of transistor MO2, and its grid meets second son control voltage signal VSF2, and its drain electrode meets the output terminal Iout of current output unit; One the 3rd electric current output PMOS transistor MO3, its breadth length ratio equals 4 times of breadth length ratio of transistor M1, its source electrode meets power supply Vdd, its grid connects the grid of transistor M2, one the 3rd a son gauge tap PMOS transistor MS3, its source electrode connects the drain electrode of transistor MO3, and its grid meets the 3rd a son control voltage signal VSF3, and its drain electrode meets the output terminal Iout of current output unit; One the 4th electric current output PMOS transistor MO4, its breadth length ratio equals 8 times of breadth length ratio of transistor M1, its source electrode meets power supply Vdd, its grid connects the grid of transistor M2, one the 4th a son gauge tap PMOS transistor MS4, its source electrode connects the drain electrode of transistor MO4, and its grid meets the 4th a son control voltage signal VSF4, and its drain electrode meets the output terminal Iout of current output unit; One row switching transistor M3, its source electrode meets the output terminal Iout of current output unit, and its grid meets column data signal Vdata, and its drain electrode is as the output terminal Icolumn of these row.
According to electric current shown in Figure 1 another arena display driver circuit, in the time of first sub, transistor MS1 conducting, transistor MS2, MS3, MS4 end, and when row switching transistor M3 conducting, current output unit 12 is exported 1 times to the electric current of unitary current.In the time of second sub, transistor MS2 conducting, transistor MS1, MS3, MS4 end, and when transistor M3 conducting, current output unit 12 is exported 2 times to the electric current of unitary current.In the time of the 3rd sub, transistor MS3 conducting, transistor MS1, MS2, MS4 end, and during transistor M3 conducting, current output unit 12 is exported 4 times to the electric current of unitary current.When the 4th son, transistor MS4 conducting, transistor MS1, MS2, MS3 end, and lead M3 when logical at transistor, and 8 times of current output unit 12 outputs are to the electric current of unitary current.
Fig. 2 is a kind of reference current element circuit 21 that shows electric current of the present invention another arena display driver circuit, can realize 1,2,4 ..., 2
N-1Doubly to the electric current output of unitary current.This reference current unit 21 comprises n sub-field current source, and each sub-field current source comprises, a sub-field current source nmos pass transistor MI1-MIn, and its source ground, its grid meets reference voltage signal Vref; One sub-field switch nmos pass transistor Msw1-Mswn, its source electrode connects the drain electrode of this sub-field current source transistor MI1-MIn, and its grid meets a son control signal VSF1-VSFn, and its drain electrode meets the output terminal Irefout of reference current element circuit.1,2,4 of the breadth length ratio unit of the being followed successively by breadth length ratio of the 1st to n sub-field current source transistor MI1-MIn ..., 2
N-1Doubly.
Reference current element circuit 21 shown in Figure 2, corresponding the 1st to n son field has only the gauge tap transistor Msw1-Mswn conducting respectively of the 1st to n, and all the other son field gauge tap transistors all end, and reference current circuit 21 exports 1,2,4 successively ..., 2
N-1Doubly to the electric current of unitary current.
The electric current another arena display driver circuit of relevant second example of the present invention is shown in Fig. 3, and this electric current another arena display driver circuit comprises the described reference current element circuit 21 of a Fig. 2; One electric current input PMOS transistor 32, its source electrode meets power supply Vdd, its grid links to each other with its drain electrode, its drain electrode connects the output terminal of this reference current element circuit: a plurality of current output unit 31, each current output unit 31 comprises, one electric current output PMOS transistor 33, its source electrode meets power supply Vdd, grid connects the grid of current input transistor 32, one row switch P MOS transistor 34, its source electrode connects the drain electrode of this electric current output transistor 33, and its grid meets column data signal Vdata, and its drain electrode is as the output terminal Icolumn of these row.
Electric current another arena display driver circuit shown in Figure 3, under the effect of a son control signal, the 1st to a n son gauge tap conducting successively, when these row switching transistor 34 conductings, this current output unit 31 is listed as output 1,2,4 to this ..., 2
N-1Doubly to the electric current of unitary current.
Fig. 4 is the electric current another arena display driver circuit that shows the 3rd special case of the present invention that can be used for tft active matrix OLED display screen.This circuit mainly is to be made of the electric current I/O unit that dynamic current mirror circuit 41 constitutes.Be characterized in to overcome the difference of each interregional TFT characteristic, for the OLED display screen provides accurate drive current.This electric current another arena display driver circuit comprises one according to reference current element circuit 21 shown in Figure 2 and a plurality of electric current I/O unit 41.Each electric current I/O unit 41 comprises: an electric current I/O PMOS transistor M42, and its source electrode meets power supply Vdd; One memory capacitance Cs, one termination power Vdd, the grid of its this electric current input/output transistors of other termination M42; One first switch nmos pass transistor M43, its drain electrode connects the grid of this electric current input/output transistors M42, and its source electrode connects the drain electrode of this electric current input/output transistors M42, and its grid meets one scan control signal VS; One second switch nmos pass transistor M44, its drain electrode connects the drain electrode of this electric current input/output transistors M42, and its source electrode connects the output terminal of this this reference current unit 21, and its grid connects the grid of this first switching transistor M43; One electric current output switch P MOS transistor M45, its source electrode connects the drain electrode of this electric current input/output transistors M42, and its grid meets this scan control signal VS; One row switch P MOS transistor M46, its source electrode connects the drain electrode of this electric current output switching transistor M45, and its grid meets a column data signal Vdata, and its drain electrode is as the output terminal Icolumn of these row.
According to electric current I/O unit 41 shown in Figure 4, sweep signal VS on this electric current I/O unit is 1, this first switching transistor M43 and the equal conducting of this second switch transistor M44, this electric current output switching transistor M45 ends simultaneously, this electric current input/output transistors M42 receives the electric current of this reference current element circuit 21 outputs, simultaneously with the correspondent voltage signal storage on memory capacitance Cs.When the sweep signal VS on this electric current I/O unit 41 is 0, this first switching transistor M43 and this second switch transistor M44 all end, this electric current output switching transistor M45 conducting, if this row switching transistor M46 conducting, this electric current input/output transistors M42 continues as this row output and consistent just now steady current under the voltage effect on this memory capacitance Cs.
The current time relation of relevant electric current of the present invention another arena display driver circuit can be with reference to figure 5.Fig. 5 uses the electric current output and the time relation synoptic diagram of the electric current another arena display driver circuit of first, second, third special case of the present invention when having shown the 16 grades of gray scales in 4 another arenaes.A display cycle is divided into 4 equal son fields, and in first to the 4th son field, this electric current another arena display driver circuit is exported 1,2,4,8 times of electric current to unitary current successively.
Fig. 6 has shown that electric current of the present invention another arena display driver circuit is used for the sequential and the electric current distribution synoptic diagram of passive matrix and active matrix OLED display screen.For passive matrix PMOLED shown in Figure 8, each row display cycle of mean allocation.For active matrix AMOLED shown in Figure 10, each son to write the time identical, OLED of each row begins to light after signal writes, by the control of line-scan circuit, each row writes data successively and lights then; And the line scan signals of next son field is controlled writing once more of each signal of going successively, can be used as refreshing last son field.Whole procedure for displaying avoids time for writing signal to showing the influence of dutycycle, has made full use of the demonstration time.So not only big electric current can be effectively avoided, and higher gray level can be reached.Replaced clock count or analog signal current to export with proportional drive current and represented gray level, it can not need adjunct circuit just can reach accurate and higher gray level expressing by the self-adjusting of the data of each son field.
Application Example
With Fig. 3 is example, and by computer simulation (software PSPICE 8.0, MicroSim company), we have realized electric current another arena display driver circuit with cmos circuit.
Simulation is that the frame period that hypothesis shows is 32mS, is divided into 4 son fields, and then each width of sub is 8mS.PMOLED display screen for 64 * 64, time of lighting of each row is 8/64=0.125mS in each son field.OLED material for present will reach the brightness of 100nits, and its current density is about 1mA/cm
2, take advantage of 0.1mm for one 0.1
2OLED, the electric current that flows through it will reach 0.8 to 1uA.For the PMOLED of our discussion, owing to each demonstration time of going only is 1/64 of the sub-field duration, so, make OLED in a son field, reach required brightness, its drive current should enlarge 64 times, promptly greater than 50-60uA, selection 50uA when we simulate.The electric current output that it is pointed out that this circuit is adjustable, and its maximum output can be up to the milliampere magnitude.In addition, because OLED has interelectrode capacity, for above OLED unit, be about the OLED material of 25nF for capacitive surface density, its electric capacity can reach about 3Pf.Therefore, under the situation of little current drives, the time that discharges and recharges of the electric capacity on the OLED is with apparent in view.And the analog result explanation, under the situation of the minimum 50/8=6.25uA of the highest 50uA, the time of discharging and recharging of OLED is acceptable.
The breadth length ratio of 4 reference current transistors is respectively 3/48,3/24 in the circuit, and 3/12 and 3/6.Their output current ratio is 1: 2: 4: 8.The breadth length ratio of electric current input and electric current output transistor is 3/12, and the breadth length ratio of switching transistor is 24/3.Different gray levels then can by the output of video data at a different sons control reference current, can be expressed 16 gray levels of 0-15 by the incompatible realization of different set of currents; And be nonlinear relationship with voltage because OLED is luminous and its electric current is linear, so adopt electric current to replace driven can realize higher gray consistency and degree of accuracy.And to expand the present invention to realize higher gray level, and do not need to increase the scale of column drive circuit, only only increase sub-number of fields order simply and get final product with corresponding reference current.
As can be seen, electric current of the present invention another arena display driver circuit is another arena uniformly-spaced, has avoided too high frequency of operation; And the electric current that uses into ratio realizes that in the combination of different sons gray scale represents, each row only needs 2 transistor driving, omitted D/A converting circuit, counting circuit or comparator circuit in other drive patterns, simplified circuit complexity, so cost has reduced greatly.
Claims (9)
1, a kind of electric current another arena display driver circuit is characterized in that it comprises that mainly a reference current unit or input current unit and one are with last current output unit; The main display cycle is divided into n son field that equates, each son drive current to the output of Organic Light Emitting Diode (OLED) display screen is respectively 1,2,4 ..., 2
N-1Times unitary current utilizes OLED electric current and luminous linear relationship, can realize 2
nThe demonstration of individual gray level, described electric current another arena display driver circuit are meant by each son field and are OLED display screen output driving current;
This reference current unit or input current unit comprise:
One reference current transistor, its source ground, its grid connects a reference voltage signal, and its drain current is a unitary current; One current input transistor, its source electrode connects power supply, and its drain electrode connects the drain electrode of this reference current transistor, and its grid links to each other with its drain electrode;
Each current output unit comprises:
The first electric current output transistor, its breadth length ratio equals the breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the transistorized grid of this electric current input current;
A first son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects first son control voltage signal, and its drain electrode connects the output terminal of this current output unit;
The second electric current output transistor, its breadth length ratio equal 2 times of breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor;
A second son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects second son control voltage signal, and its drain electrode connects the output terminal of this current output unit;
The 3rd electric current output transistor, its breadth length ratio equal 4 times of breadth length ratio of reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor;
The 3rd a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the 3rd a son control voltage signal, and its drain electrode connects the output terminal of this current output unit;
The 4th electric current output transistor, its breadth length ratio equal 8 times of breadth length ratio of this reference current transistor, and its source electrode connects power supply, and its grid connects the grid of this current input transistor;
The 4th a son gauge tap transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the 4th a son control voltage signal, and its drain electrode connects the output terminal of this current output unit;
The row switching transistor, its source electrode connects the output terminal of this current output unit, and its grid connects the column data signal, and it leaks the output terminal of level as these row.
2, electric current according to claim 1 another arena display driver circuit is characterized in that described reference current transistor is a nmos pass transistor; Described current input transistor, electric current output transistor, a son gauge tap transistor and row switching transistor are the PMOS transistor.
3, electric current according to claim 1 another arena display driver circuit is characterized in that described reference current element circuit can realize 1,2,4 ..., 2
N-1Doubly to the electric current output of unitary current, it mainly comprises n sub-field current source, and each sub-field current source comprises:
Sub-field current source transistor, its source ground, its grid connects reference voltage signal;
Sub-field switch transistor, its source electrode connect the leakage level of this sub-field current source transistor, and its grid connects a son control signal, and it leaks the output terminal that level connects this reference current element circuit.
4, electric current according to claim 3 another arena display driver circuit is characterized in that the sub-field current source transistor of described reference current element circuit and this sub-field switch transistor are nmos pass transistor.
5, electric current according to claim 3 another arena display driver circuit, it is characterized in that described reference current element circuit the 1st to n sub-field current source transistor the breadth length ratio unit of being followed successively by breadth length ratio 1,2,4 ..., 2
N-1Doubly; The the 1st to n the transistorized grid of sub-field switch connects the 1st to a n control signal successively.
6, electric current according to claim 1 another arena display driver circuit is characterized in that it mainly comprises:
Reference current element circuit according to claim 3;
Current input transistor, its source electrode connects power supply, and its grid links to each other with its drain electrode, and its drain electrode connects the output terminal of this reference current element circuit;
One with last current output unit, and each current output unit comprises:
The electric current output transistor, its source electrode connects power supply, and its grid connects the grid of this current input transistor; The row switching transistor, its source electrode connects the drain electrode of this electric current output transistor, and its grid connects the column data signal, and its drain electrode is as the output terminal of these row.
7, electric current according to claim 6 another arena display driver circuit is characterized in that described current input transistor, electric current output transistor and row switching transistor are the PMOS transistor.
8, a kind of electric current according to claim 1 another arena display driver circuit, it is characterized in that, it comprises that mainly reference current element circuit according to claim 3 and one inputed or outputed the unit with last electric current, and each electric current inputs or outputs the unit and comprises:
Electric current inputs or outputs transistor, and its source electrode connects power supply;
Memory capacitance, the one termination power, its other this electric current of a termination inputs or outputs transistorized grid;
First switching transistor, its drain electrode connects this electric current and inputs or outputs transistorized grid, and its source electrode connects this electric current and inputs or outputs transistor drain, and its grid connects the one scan control signal;
The second switch transistor, its drain electrode connects this electric current and inputs or outputs transistor drain, and its source electrode connects the output terminal of this reference current unit, and its grid connects the grid of this first switching transistor;
The electric current output switching transistor, its source electrode connects this electric current and inputs or outputs transistor drain, and its grid connects the grid of this first switching transistor;
The row switching transistor, its source electrode connects this electric current and inputs or outputs transistor drain, and its grid connects a column data signal, and its drain electrode is as the output terminal of these row.
9, electric current according to claim 8 another arena display driver circuit, it is characterized in that described electric current inputs or outputs transistor, electric current output switching transistor and this row switching transistor and is the PMOS transistor, described first switching transistor and described second switch transistor are nmos pass transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031050794A CN1190765C (en) | 2003-03-06 | 2003-03-06 | Current display drive circuit by field |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031050794A CN1190765C (en) | 2003-03-06 | 2003-03-06 | Current display drive circuit by field |
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| CN1432985A CN1432985A (en) | 2003-07-30 |
| CN1190765C true CN1190765C (en) | 2005-02-23 |
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| CNB031050794A Expired - Fee Related CN1190765C (en) | 2003-03-06 | 2003-03-06 | Current display drive circuit by field |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005208241A (en) * | 2004-01-21 | 2005-08-04 | Nec Electronics Corp | Light emitting element driving circuit |
| KR100670137B1 (en) | 2004-10-08 | 2007-01-16 | 삼성에스디아이 주식회사 | Digital/analog converter, display device using the same and display panel and driving method thereof |
| KR100658619B1 (en) | 2004-10-08 | 2006-12-15 | 삼성에스디아이 주식회사 | Digital/analog converter, display device using the same and display panel and driving method thereof |
| CN103198797B (en) * | 2013-04-26 | 2015-02-25 | 深圳市华星光电技术有限公司 | Driving method and pixel units of active matrix organic light emitting diode panel |
| TWI747119B (en) * | 2018-12-27 | 2021-11-21 | 聯詠科技股份有限公司 | Circuit and method for driving light sources |
| CN109584789B (en) * | 2019-01-30 | 2020-08-25 | 上海艾为电子技术股份有限公司 | LED drive circuit and light emitting circuit |
| CN110534054B (en) * | 2019-07-31 | 2021-06-22 | 华为技术有限公司 | Display driving method and device, display device, storage medium and chip |
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