CN101116129B

CN101116129B - Method and system for programming, calibrating and driving a light emitting device display

Info

Publication number: CN101116129B
Application number: CN2005800480205A
Authority: CN
Inventors: A·内森; G·R·查吉; P·塞尔瓦蒂
Original assignee: Ignis Innovation Inc
Current assignee: Ignis Innovation Inc
Priority date: 2004-12-15
Filing date: 2005-12-15
Publication date: 2011-03-30
Anticipated expiration: 2025-12-15
Also published as: CA2490860A1; CN101116129A

Abstract

This invention presents a scheduling method and algorithm for calibration of pixels in active-matrix organic light-emitting diode (AMOLED) displays. The pixels are calibrated based on their aging and usage during the normal operation of active matrix display. The display data is used to determine the pixels with high brightness for calibration, which guarantees high speed and accurate calibration. This method can be used with any current programmed pixels, in particular, current mirror based designs.

Description

Be used for to light emitting device display programme, calibration and method of driving and system

Technical field

The present invention relates to a kind of display technique, more specifically, relate to a kind of be used for to light emitting device display programme, calibration and method of driving and system.

Background technology

Recently, have amorphous silicon (a-Si), polysilicon, organic or other drive active matrix organic light-emitting diode (AMOLED) display of backboard owing to possess the advantage that is better than active matrix liquid crystal display, and become more attractive.These advantages comprise, for example, use a-Si, make except its low temperature manufacturing can be extensive use of different substrates and can realize also having advantages such as low production cost, high resolving power and wide visual angle the demonstration flexibly.

The AMOLED display comprises the array of being made up of the row and column of pixel, is provided with Organic Light Emitting Diode (OLED) and backboard electronic equipment in the array that row and column is formed.Because OLED is a current driving device, the image element circuit of AMOLED should be able to provide accurate and constant drive current.

United States Patent (USP) the 6th, 594 discloses a kind of method and system of calibrating passive pixel No. 606.United States Patent (USP) the 6th, 594, No. 606 measurement data line voltages, and utilize precharge measurement result.Yet, because the active-matrix calibration should be aging aging all effective with OLED to backboard, so this technology can not provide active-matrix required accuracy.In addition, after precharge, must carry out current programmed.Because parasitic line capacitance, current-driven pixel current programmed very slow, and can be subjected to the influence of the unevenness of big display.When using little electric current to programme, speed can become a problem.

People have proposed other compensation technique.Yet, still need to provide a kind of constant luminance can be provided, obtain pin-point accuracy and reduce the method and system of image element circuit burn-in effects.

Summary of the invention

An object of the present invention is to provide a kind of method and system of eliminating or alleviating at least one defective of existing system.

According to an aspect of the present invention, a kind of method of the array of display that has a plurality of image element circuits that are arranged in rows and columns being carried out real time calibration is provided, this method comprises the following steps: to generate the priority list of pixel, be used for based on showing and last calibration data is distinguished the priority ranking of the pixel that is used to calibrate, use priority list to select one or more (n) pixel, utilize than the higher electric current of the threshold current that is used to calibrate the selected pixel that goes out is programmed; N pixel from chained list in the select column of selection array of display; Pixel in the select column is programmed, comprising: the pixel current of n pixel of monitoring also obtains calibration data; Upgrade compensation memory to be used for calibration according to calibration data; Priority list to programming next time sorts.

According to a further aspect in the invention, a kind of system that the array of display that has a plurality of image element circuits that are arranged in rows and columns is carried out real time calibration is provided, each image element circuit has luminescent device and driving transistors, this system comprises: be used to control the calibration schedules device of the programming and the calibration of array of display, it comprises: the priority list of listing one or more pixels that are used to calibrate according to video data; In programming cycle, be the one or more pixels startup calibration modes in the select column of from priority list, selecting, and be the module of the residual pixel startup normal manipulation mode in the select column in programming cycle; Be used to monitor the watch-dog of the pixel current of the pixel under the calibration mode on the select column; Be used for producing the generator of calibration data according to monitored results; Be used to store the storer of calibration data; And, when the pixel of normal manipulation mode is programmed, regulate the regulator of the programming data that is applied to array of display according to calibration data.

According to a further aspect in the invention, provide a kind of system that is used to have the array of display of image element circuit, this image element circuit is programmed by data line, and this system comprises: data source is used for programming data is provided to image element circuit; The voltage source of the Current Control that is associated with voltage source is used for the electric current on the data line is changed into the voltage that is associated with electric current to extract the time-varying parameter of image element circuit.

According to a further aspect in the invention, a kind of system that is used for array of display is provided, array of display wherein comprises a plurality of image element circuits, each image element circuit comprises driving transistors, at least one switching transistor, holding capacitor and luminescent device, this system comprises: watch-dog is used to monitor the curtage of image element circuit; Data processing unit is used to control the operation of array of display, and data processing unit extracts about the aging information of image element circuit according to the curtage of monitoring, and the state of definite image element circuit; Driver is by data processing unit control and be used for providing programming and calibration data according to the state of image element circuit for image element circuit.

According to a further aspect in the invention, a kind of method that drives array of display is provided, this array of display comprises a plurality of image element circuits, each image element circuit comprises driving transistors, at least one switching transistor, holding capacitor and luminescent device, and this method comprises the following steps: to apply curtage to image element circuit; Monitoring flow is crossed the curtage of image element circuit; Curtage according to monitoring extracts about the aging information of image element circuit, and the state of definite image element circuit; Provide operating voltage to image element circuit, comprise programming and the calibration data of determining image element circuit according to the state of image element circuit.

According to a further aspect in the invention, a kind of method that drives array of display is provided, this array of display comprises a plurality of image element circuits, each image element circuit comprises driving transistors, at least one switching transistor, holding capacitor and luminescent device, and this method comprises the following steps: to apply curtage to luminescent device; Monitoring flow is crossed the curtage of luminescent device; According to the curtage of monitoring, the variation of prediction luminescent device; With the biasing that is associated with the variation of luminescent device is provided for luminescent device.

According to a further aspect in the invention, a kind of system that is used to drive array of display is provided, this array of display comprises a plurality of image element circuits, each image element circuit comprises driving transistors, at least one switching transistor, holding capacitor and luminescent device, this system comprises: watch-dog is used to monitor the curtage of image element circuit; Data processing unit is used for the variation according to the curtage prediction luminescent device of monitoring, and the state of definite image element circuit; And, be used to luminescent device that the circuit of the biasing that is associated with the variation of luminescent device is provided.

According to a further aspect in the invention, a kind of system that is used for array of display is provided, array of display wherein comprises a plurality of image element circuits, each image element circuit comprises driving transistors, at least one switching transistor, holding capacitor and luminescent device, this luminescent device is arranged in and is used for program path that image element circuit is programmed, and this system comprises: the controller that is used to control the operation of array of display; Be used for the driver that image element circuit provides operating voltage that is controlled to be according to controller; Provide operating voltage in programming cycle for image element circuit with being used for, so that the driver that luminescent device is removed from program path.

Summary of the invention of the present invention needn't be described all features of the present invention.

By reading following detailed description of the preferred embodiment also in conjunction with the accompanying drawings, those skilled in the art will know others of the present invention and feature.

Description of drawings

By the detailed description of carrying out below with reference to accompanying drawing, will be more readily apparent from these and other feature of the present invention, wherein:

Fig. 1 shows the process flow diagram that correction scheduling according to an embodiment of the invention is handled;

Fig. 2 shows and is used for the diagrammatic sketch of an example of system architecture of correction scheduling of execution graph 1;

Fig. 3 shows the diagrammatic sketch that is used for the system architecture of voltage subtraction, programming and driving according to an embodiment of the invention;

Fig. 4 shows the example of extraction, programming and drive system of Fig. 3 and the diagrammatic sketch of image element circuit;

Fig. 5 shows another example of extraction, programming and drive system of Fig. 3 and the diagrammatic sketch of image element circuit;

Fig. 6 shows another example of extraction, programming and drive system of Fig. 3 and the diagrammatic sketch of image element circuit;

Fig. 7 shows another example of extraction, programming and drive system of Fig. 3 and the diagrammatic sketch of image element circuit;

Fig. 8 shows the diagrammatic sketch of the image element circuit of having used step calibration driving according to an embodiment of the invention;

Fig. 9 shows the diagrammatic sketch of the driving transistors of example of driver and extraction module and Fig. 8;

Figure 10 shows the diagrammatic sketch of an example of the extraction algorithm of being carried out by the DPU module of Fig. 9;

Figure 11 shows the diagrammatic sketch of another example of the extraction algorithm of being carried out by the DPU module of Fig. 9;

Figure 12 shows the sequential chart of an example of the waveform that is used for the step calibration driving;

Figure 13 shows the sequential chart of another example of the waveform that is used for the step calibration driving;

Figure 14 shows the diagrammatic sketch of the image element circuit that can use the step calibration driving;

Figure 15 shows the curve map of the analog result that is used for the step calibration driving;

Figure 16 shows and utilizes array of display to carry out the diagrammatic sketch of an example of system architecture of step calibration driving;

Figure 17 shows the sequential chart of an example of the waveform of the system architecture that is applied to Figure 16;

Figure 18 shows the sequential chart of an example of the waveform that is used for the voltage/current extraction;

Figure 19 shows the sequential chart of another example of the waveform that is used for the voltage/current extraction;

Figure 20 is the diagrammatic sketch that can use the image element circuit that the voltage/current of Figure 19 extracts;

Figure 21 shows the sequential chart of another example of the waveform that is used for the voltage/current extraction;

Figure 22 shows the diagrammatic sketch of the image element circuit of the voltage/current extraction that can use Figure 21;

Figure 23 shows the diagrammatic sketch based on the image element circuit of mirror image of having used that OLED according to an embodiment of the invention removes;

Figure 24 shows the diagrammatic sketch of the program path of the Figure 23 when having used the OLED removal;

Figure 25 shows the diagrammatic sketch of an example of the system architecture that is used for the OLED removal;

Figure 26 shows the curve map of the analog result that is used for the voltage on the different IDATA line of threshold voltage.

Embodiment

Now use and comprise that luminescent device and a plurality of transistorized pixel describe embodiments of the invention.Luminescent device can be Organic Light Emitting Diode (OLED).It should be noted that " pixel " and " image element circuit " is used interchangeably.

Below describe real time calibration scheduling in detail to array of display with a plurality of pixels.Fig. 1 shows calibration schedules according to an embodiment of the invention and handles.According to this technology, according to the pixel ageing in the normal running of array of display and/or make and be used for pixel is calibrated.

In step S2, produce the chained list of pixel.Chained list comprises the sign of the pixel with high brightness that is used to calibrate.Use chained list to dispatch the priority of calibration.

In step S4, select " n " according to the instability along with the time (for example, the characteristic skew of transistor and luminescent device) of display size and expectation.The pixel quantity that " n " representative is calibrated in each programming cycle." n " can be more than or equal to 1.

Then, at step S6, programming cycle begins.Step S6 comprises step S8-S16.Select column execution in step S8-S16 to array of display.

In step S8, select " n " individual pixel the select column from the starting end of chained list, hereinafter be called " selected pixel ".

In step S10, for selected pixel starts " calibration mode ", for the residual pixel in the select column in the array of display starts " normal manipulation mode ".

In step S12,, all pixels in the select column are programmed by the voltage source driver on the data line that is connected to pixel (for example, Fig. 2 28).

For selected pixel, monitoring is by the electric current of data line in programming cycle.For the pixel except that selected pixel in the select column, use to be stored in storer (for example, Fig. 2 34), hereinafter be called the data in " Δ V compensation memory ", improve corresponding program voltage.

In step S14, monitor current and the expectation electric current that must flow through data line are made comparisons.Then, produce the calibration data curve of selected pixel.According to the calibration data curve, upgrade Δ V compensation memory.

Pixel be stored in calibration data curve in the Δ V compensation memory will be used to when this pixel is in normal manipulation mode, in next programming cycle, the to raise program voltage of this pixel.

In step S16, the sign of selected pixel is sent to the end of chained list.Selected pixel has minimum calibration priority in chained list.

During display operation (S6-S16), chained list will provide the priority list after the ordering of the pixel that must calibrate.It should be noted that in description the use of term " chained list " and term " priority list " is interchangeable.

Operation is returned (S18) to S8.Next programming cycle begins.Activate the new row in (selections) array of display, and, new " n " the individual pixel the row of activation of selecting to make new advances from the chained list top.The calibration data that use obtains for new selected pixel upgrades Δ V compensation memory.

Now describe the quantity " n " of selected pixel in detail.As mentioned above, quantity " n " is based on that the instability of the family curve expectation in time of display size and device determines.Suppose the N=3 * m that adds up to of pixel N _l* m ₂, m wherein ₁And m ₂Be respectively the quantity of row and column in the array of display.

The maximum rate of change of family curve skew is K (=Δ I/ Δ t.I).Each programming cycle is got t=1/f.m ₂After whole demonstration was calibrated, characteristic greatest hope side-play amount was Δ I/I=K.t.N/n＜e, and wherein e is an allowable error.After this, can restart to calibrate, and eliminate error.As can be known, n〉K.t.N/e, perhaps n〉3.K.m ₁/ f.e.For example, if K=1%/hr, m ₁=1024, f=60Hz, and e=0.1%, then n〉0.14, this means needs 5 programming cycle to carry out primary calibration.This can realize that this alignment unit only moves once by an alignment unit in 5 programming cycle.Each alignment unit can carry out the calibration of a pixel in a programming cycle.Suppose e=0.01%, n〉1.4.This means that two alignment units need calibrate two pixels in each programming cycle.This just shows and can implement this calibration system originally with low-down one-tenth.

Because the skew of characteristic will be As time goes on and slack-off, so can reduce the frequency of calibrating automatically when display ages.In addition, can utilize the different electric currents that depend on video data that the chosen pixel that is used to calibrate is programmed.Unique condition is that its program current is greater than reference current.Therefore, can calibrate a pixel with many times of luminance levels, to obtain higher accuracy.

Describe chained list below in detail.In chained list, listed the pixel that is used to calibrate with high brightness.The pixel of using video data to be identified for calibrating with high brightness.When electric current is very weak, calibrate very slow, and normally inaccurate.In addition, characteristic maximum offset occurs on the pixel with heavy current.Thereby, for accuracy and the speed that improves calibration, select and must use than threshold current I _THThe pixel that stronger electric current is programmed, and it is stored in the chained list.

I _THBe variable, and can be " 0 ".For I _TH=0, all pixels all are listed in the chained list, and no matter how program current all carries out calibration to all pixels.

Above-mentioned calibration schedules technology can be applicable to any current programmed pixel, for example, but is not limited to, based on the pixel of current mirror.

Fig. 2 shows an example of the system architecture of the calibration schedules that is used for execution graph 1.The system 30 that is used for the array of display 10 with a plurality of image element circuits 12 is implemented Fig. 2 of calibration schedules algorithm is provided.Image element circuit 12 is current programmed image element circuits, such as, but be not limited to, based on the pixel of current mirror.Image element circuit 12 is aligned to row and column.

Image element circuit 12 can comprise OLED and a plurality of transistor (for example, TFT).Can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology and (for example, MOSFET) make transistor.Array of display 10 can be the AMOLED array of display.

By being connected to gate line 14 on the gate drivers 20, being connected to the data line 16 on the voltage data driver 28 and the power lead that is connected on the power supply 24 is operated image element circuit 12.In Fig. 2, as an example, show two data lines, two gate lines and two power leads.Obviously, data line, the gate line more than two and the power lead more than two more than two can be set in array of display 10.

System 30 comprises the calibration schedules device and is used to control programming and the calibration storage block 32 that shows display 10, and the Δ V compensation memory 34 that is used to store Δ V bucking voltage (numerical value).In each programming cycle, select the row in the array of display 10.Calibration schedules device and storage block 32 are that the select column (that is data line) in this programming cycle starts normal manipulation mode or calibration mode.

System 30 also comprises the supervisory system that is used for monitoring and measuring pixel current.This supervisory system comprises switch 36 and 38 and have a voltage sensor 40 of precision resistor 42.In Fig. 2, for example, for each data line is provided with switch 36 and 38.

System 30 also comprises the generator that produces Δ V bucking voltage based on monitored results.Generator comprises analog/digital converter (A/D) 44, comparer 46, and transducer (translator) 48.A/D44 converts the simulation output of voltage sensor 40 to numeral output.Comparer 46 compares the output of numeral output with transducer 48.Transducer 48 is imported 52 to digital data and is implemented function f (V).Transducer 48 changes into the voltage data input with current data input 52 by f (V).The comparative result of comparer 46 is stored in the Δ V compensation memory 34.

System 30 also comprises totalizer 50, is used for numerical data input 52 and the Δ V bucking voltage addition that is stored in Δ V compensation memory 34.Voltage data driver 28 comes driving data lines based on the output of totalizer 50.Regulate the programming data of data line by adding Δ V bucking voltage.

When calibration schedules device and storage block 32 are chosen data line when starting normal manipulation mode, switch 36 is activated.The voltage of voltage data driver 28 is exported on the pixel that is applied directly on this data line.

When calibration schedules device and storage block 32 started calibration mode for this data line, switch 38 was activated.By precision resistor 42 voltage is imposed on pixel on this data line.In the final stage (that is, when initial transient finishes) of programming time, by the voltage drop at voltage sensor 40 measurement resistor 42 two ends.The voltage drop that A/D44 is monitored voltage sensor 40 converts numerical data to.If pixel is current programmed image element circuit, the value of the voltage drop that then obtains is proportional with the electric current that flows through pixel.Comparer 46 will be worth the expectation value that is obtained with transducer 48 and compare.

Difference between expectation value and the measured value is stored in the Δ V compensation memory 34, and this difference will be used to programming cycle subsequently.This difference will be used to regulate and be used in the future this pixel being carried out data programmed voltage.

Calibration schedules device and storage block 32 can comprise above-mentioned chained list.During beginning, generate chained list automatically.This chained list can be the tabulation of pixel.Yet, can make amendment in operating process.

Calibration to image element circuit with high brightness can guarantee high speed required in the display of big or small size and calibration accurately.

Because the working voltage programming technique drives array of display 10, so can be fast and can be used to high resolving power and large-area display.

Because the simplicity of speed, accuracy and enforcement, calibration schedules The Application of Technology scope is from being used for the electroluminescent device of cell phone, personal organizer, watch-dog, TV, to large-area display board.

System's 30 monitoring and the voltage drop of measuring the time-varying parameter that depends on pixel, and produce required programming data.Yet, can extract the time-varying parameter of pixel with any other mechanism that is different from the mechanism among Fig. 2.

Describe the another kind of technology that is used to programme, extract the time-varying parameter of pixel and drives pixel in detail with reference to figure 3-7.This technology comprises the voltage subtraction that is used to calibrate.The information calibration programming data that utilization extracts produces stable in time pixel current.Use this technology, extract the aging conditions of pixel.

Fig. 3 shows the system architecture that is used to carry out voltage subtraction, programming and driving according to an embodiment of the invention.The system of Fig. 3 carries out voltage subtraction and programming to the image element circuit 60 of current-mode.Image element circuit 60 comprises luminescent device and a plurality of transistor that has the driving transistors (not shown).Transistor can be TFT.

Image element circuit 60 is selected by selection wire SEL, and drives by the DATA on the data line 61.Provide voltage source 62, with program voltage V _PWrite in the image element circuit 60.Provide the voltage source (CCVS) 63 of Current Control, so that the current transitions on the data line 61 is become voltage Vext with positive node and negative nodal point.Display controller and scheduler 64 operation image element circuits 60.Display controller and scheduler 64 monitoring are from the extraction voltage Vext of CCVS63 output, and control voltage source 62 then.

The resistance of CCVS 63 can be ignored.Thereby the electric current on the data line 61 can be written as:

I _Line＝I _piexl＝β(V _P-V _T) ²...(1)

I wherein _LineElectric current on the representative data line 61, I _PiexlThe represent pixel electric current, V _TThe threshold voltage of the driving transistors that comprises in the representational of pixel circuits 60, and β represents the gain parameter of TFT characteristic.

When the threshold voltage of drive TFT along with the time when increasing, the electric current on the data line 61 reduces.Extract voltage Vext by monitoring, display controller and scheduler 64 are determined the side-play amount of threshold voltage.

Threshold voltage V that can following calculating driving transistors _T:

V _T＝V _P-(I _Line/β) ^0.5...(2)

Use information extraction to revise program voltage V _PCan in the time of each frame, carry out extraction procedure to one or several pixel.

Fig. 4 shows an example of the system that is used for voltage subtraction, programming and driving of Fig. 3, and this system adopts the image element circuit 70 of top light emitting current element.Image element circuit 70 comprises OLED71, holding capacitor 72, driving transistors 73 and switching transistor 74 and 75.

Transistor 73,74 and 75 can be n type TFT.Yet these transistors 73,74 and 75 also can be the p transistor npn npns.Be applied to the voltage subtraction of image element circuit 70 and the image element circuit that programming technique can be applicable to have the p transistor npn npn equally.

Driving transistors 73 is connected to data line 76 by switching transistor 75, and is connected on the OLED 71, also is connected on the holding capacitor 72 by switching transistor 74.The gate terminal of driving transistors 73 is connected on the holding capacitor 72.Switching transistor 74 and 75 gate terminal are connected on the selection wire SEL.OLED 71 is connected on voltage supplying electrode or the vdd line.Image element circuit 70 is selected by selection wire SEL and is driven by the DATA on the data line 76.

Current conveyor (CC) 77 has X, Y and Z end, and is used to extract the electric current on the data line 76, and can not increase its load.Voltage source 78 is applied to program voltage at the Y end of CC77.In CC77, make the X end have and the identical voltage of Y end by feedback.Simultaneously, the electric current on the X end of CC77 is copied to the Z end.The voltage source of Current Control (CCVS) 79 has positive node and negative nodal point.CCVS 79 changes into voltage Vext with the electric current on the Z end of CC 77.

Vext is offered display controller and the scheduler 64 of Fig. 3, therein, extract the threshold voltage of driving transistors 73.Display controller and scheduler 64 come control voltage source 78 based on the threshold voltage that extracts.

Fig. 5 shows another example of the system that is used for voltage subtraction, programming and driving of Fig. 3, and it has adopted the image element circuit 80 of bottom-emission current element.Image element circuit 80 comprises OLED81, holding capacitor 82, driving transistors 83 and switching transistor 84 and 85.

Transistor

83,84 and 85 can be n type TFT.Yet these

transistors

83,84 and 85 also can be the p transistor npn npns.

Driving transistors 83 is connected to data line 86 by switching transistor 85, and is connected on the OLED 81, is also connected on the holding capacitor 82.The gate terminal of driving transistors 83 is connected on the voltage supply line VDD by switching transistor 84.

Switching transistor

84 and 85 grid are connected on the selection wire SEL.Image element circuit 80 is selected by selection wire SEL, and is driven by the DATA on the data line 86.

Current conveyor (CC) 87 has X, Y and Z end, is used to extract the electric current on the data line 86, and can increase its load.Voltage source 88 will be born on the Y end that program voltage is applied to CC 87.In CC 87, make the X end have and the identical voltage of Y end by feedback.Simultaneously, the electric current on the X end of CC 87 is copied to the Z end.The voltage source of Current Control (CCVS) 89 has positive node and negative nodal point.CCVS 89 changes into voltage Vext with the electric current on the Z end of CC 87.

Vext is offered display controller and the scheduler 64 of Fig. 3, therein, extract the threshold voltage of driving transistors 83.Display controller and scheduler 64 come control voltage source 88 based on the threshold voltage that extracts.

Fig. 6 shows another example of the system that is used for voltage subtraction, programming and driving of Fig. 3, and it has adopted top light emitting current mirror pixel circuit 90.Image element circuit 90 comprises OLED 91, holding capacitor 92, mirrored

transistor

93 and 94 and switching transistor 95 and 96.

Transistor

93,94,95 and 96 can be n type TFT.Yet these

transistors

93,94,95 and 96 also can be the p transistor npn npns.

Mirrored transistor 93 is connected to data line 97 by switching transistor 95, is connected to holding capacitor 92 by switching transistor 96.Mirrored transistor 93 is connected on holding capacitor 92 and the switching transistor 96 with 94 gate terminal.Mirrored transistor 94 is connected on voltage supplying electrode or the vdd line by OLED

91.Switching transistor

85 and 86 grid are connected to be selected on the SEL line.Image element circuit 90 is selected by selection wire SEL, and is driven by the DATA on the data line 97.

Current conveyor (CC) 98 has X, Y and Z end, and is used to extract the electric current of data line 97, and can not increase its load.Voltage source 99 is applied to positive program voltage on the Y end of CC 98.In CC 98, the X end is had and the identical voltage of Y end by feedback.Simultaneously, the electric current on the X end of CC 98 is copied to the Z end.The voltage source of Current Control (CCVS) 100 has positive node and negative nodal point.CCVS 100 changes into voltage Vext with the electric current on the Z end of CC 98.

Vext is offered display controller and the scheduler 64 of Fig. 3, therein, extract the threshold voltage of driving transistors 93.Display controller and scheduler 64 come control voltage source 99 based on the threshold voltage that extracts.

Fig. 7 shows another example of the system that is used for voltage subtraction, programming and driving of Fig. 3, and it adopts bottom-emission current mirror pixel circuit 110.Image element circuit 110 comprises OLED 111, holding capacitor 112, mirrored

transistor

113 and 116 and switching transistor 114 and 115.Transistor 113,114,115 and 116 can be n type TFT.Yet these transistors 113,114,115 and 116 also can be the p transistor npn npns.

Mirrored transistor 113 is connected on the data line 117 by switching transistor 114, is connected on the holding capacitor 112 by switching transistor 115.Mirrored

transistor

113 and 116 gate terminal are connected on holding capacitor 112 and the switching transistor 115.Mirrored transistor 116 is connected on the voltage supply line VDD.Mirrored transistor 113,116 and holding capacitor 112 are connected on the

OLED111.Switching transistor

114 and 115 gate terminal are connected on the selection wire SEL.Image element circuit 110 is selected by selection wire SEL, and is driven by the DATA on the data line 117.

Current conveyor (CC) 118 has X, Y and Z end, and is used to extract the electric current on the data line 117, and can not increase its load.Voltage source 119 is applied to positive program voltage on the Y end of CC 118.In CC 118, make the X end of CC 118 have and the identical voltage of Y end by feedback.Simultaneously, the electric current on the X end of CC118 is copied to the Z end.The voltage source of Current Control (CCVS) 120 has positive node and negative nodal point.CCVS 120 changes into voltage Vext with the electric current on the Z end of CC 118.

Vext is offered display controller and the scheduler 64 of Fig. 3, therein, extract the threshold voltage of driving transistors 113.Display controller and scheduler 64 come control voltage source 119 based on the threshold voltage that extracts.

With reference to figure 3-7, can utilize the voltage subtraction technology to extract the time-varying parameter of pixel (for example, threshold shift).Thereby, can use information extraction to calibrate program voltage, obtain stable in time pixel current.Because OLED (for example, 71 of Fig. 4,81 of Fig. 5,91 of Fig. 6, Fig. 7 111) voltage directly influence electric current, so also can use above-mentioned voltage subtraction Driving technique to extract the aging and threshold shift of OLED.

Above-mentioned voltage subtraction technology can be used to the image element circuit of any current-mode, comprises current mirror and current element image element circuit structure, and can be applicable to the array of display 10 of Fig. 2.Use information extraction, can be provided in the steady current that has nothing to do with pixel ageing under the long-time display operation.Thereby, the life-span that can effectively improve display operation.

It should be noted that transistor in the image element circuit of Fig. 3-7 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology and (for example, MOSFET) make.The image element circuit of Fig. 3-7 can constitute the AMOLED array of display.

Describe the another kind of technology that is used to programme, extract the time-varying parameter of pixel and drives pixel in detail with reference to figure 8-17.This technology comprises the step calibration Driving technique.In this step calibration Driving technique, extract information about pixel ageing (for example, threshold shift).The information of extracting will be used to produce stable pixel current/brightness.Although use an extractive technique, the resolution of the aging conditions of extracting is limited by display driver.Equally, owing to extract pixel under operating conditions, so can compensate dynamic effect, this is similar to drive cycle.

Fig. 8 shows and has used the image element circuit 160 that step calibration according to an embodiment of the invention drives.Image element circuit 160 comprises OLED 161, holding capacitor 162 and driving transistors 163 and switching transistor 164 and 165.Image element circuit 160 is current programmed 3-TFT image element circuits.A plurality of image element circuits 160 can constitute the AMOLED display.

Transistor 163,164 and 165 is n type TFT.Yet transistor 163,164 and 165 also can be the p transistor npn npn.The step calibration Driving technique that is applied to image element circuit 160 also can be applicable to have the image element circuit of p transistor npn npn.Transistor 163,164 and 165 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology (for example, MOSFET) makes.

The gate terminal of driving transistors 163 is connected on the signal wire VDATA by switching transistor 164, is also connected on the holding capacitor 162.The source terminal of driving transistors 163 is connected to common ground.The drain electrode end of driving transistors 163 is connected on the monitoring cable MONITOR by switching transistor 165, is also connected to the cathode electrode of OLED 161.

The gate terminal of switching transistor 164 is connected to selection wire SEL1.The source terminal of switching transistor 164 connects the gate terminal of driving transistors 163, and is connected to holding capacitor 162.The drain electrode end of switching transistor 164 is connected to VDATA.

The gate terminal of switching transistor 165 is connected to selection wire SEL2.The source terminal of switching transistor 165 is connected to MONITOR.The drain electrode end of switching transistor 165 is connected to the drain electrode end of driving transistors 163 and the cathode electrode of OLED 161.The anode electrode of OLED 161 is connected to voltage supplying electrode or vdd line.

Transistor 163 with 164 and holding capacitor 162 be connected at node A3 place.Transistor 163 with 165 and OLED 161 be connected at Node B 3 places.

Fig. 9 shows example of driver and extraction module 170 and the driving transistors 163 of Fig. 8.In Fig. 9, Rs171a and Rs171b be the ON resistance of representation switch transistor (for example, 164 of Fig. 8,165) respectively.The holding capacitor of Cs represent pixel, C _OLEDRepresent OLED electric capacity, CP represents the line stray capacitance.In Fig. 9, OLED is represented as electric capacity.

Use module 173 in extracting cycle, to extract the threshold voltage of driving transistors.Module 173 can be current sense amplifier (SA) or current comparator.In description, module 173 is called " SA module 173 ".

If the electric current on the MONITOR line is higher than reference current (IREF), then the output of SA module 173 (that is the trigger among Figure 10,11) becomes 1.If the electric current on the MONITOR line is less than reference current (IREF), then the output of SA module 173 becomes 0.

It should be noted that SA piece 173 can be shared between several row, thereby reduce expense.In addition, can also carry out the calibration of pixel current one at a time, therefore can be between all row shared extraction circuit.

Provide data processing unit (DPU) module 172 to come control programming cycle, contrast and brightness, to carry out calibration procedure and controlling and driving cycle.DPU module 172 is carried out extraction algorithms, extracting the threshold voltage of (estimation) driving transistors based on the output valve of SA module 173, and is operatively connected to the driver 174 on the driving transistors 163.

Figure 10 shows an example of the extraction algorithm of being carried out by the DPU module 172 of Fig. 9.The algorithm of Figure 10 is the part of DPU module 172.In Figure 10, V _T(i j) represents in last extracting cycle pixel (i, the j) threshold voltage of Ti Quing, V _sRepresent the resolution of driver 174, the row of " i " represent pixel array, the row of " j " represent pixel array.Trigger transmits the comparative result of the SA module 173 of Fig. 9.Determined the actual V of pixel less than state 180 _TLess than prediction V _T(V _TM) situation, equal the prediction V that state 181 has been determined pixel _T(V _TM) and actual V _TSituation about equating has been determined the actual V of pixel greater than state 182 _TGreater than prediction V _T(V _TM) situation.

The DPU module 172 of Fig. 9 is determined intermediate threshold voltage V _TMAs follows:

(A1) when s (i, j)=during less than state (180), actual threshold voltage is less than V _T(i, j), with V _TMBe arranged to (V _T(i, j)-V _s).

(A2) (i, j)=when equaling state (181), actual threshold voltage equals V as s _T(i, j), with V _TMBe arranged to V _T(i, j).

(A3) when s (i, j)=during greater than state (182), actual threshold voltage is greater than V _T(i, j), with V _TMBe arranged to (V _T(i, j)+V _s).

Wherein, (i, j) representative is stored in pixel (i, previous state j) in the calibration storage (for example, 208 of Figure 16) to s.

Figure 11 shows another example of the extraction algorithm of being carried out by the DPU module 172 of Fig. 9.The algorithm of Figure 11 is the part of the DPU module 172 of Fig. 9.V in Figure 11 _T(i, j) represent pixel (i, the j) threshold voltage that in a last extracting cycle, extracts, V _sRepresent the resolution of driver 174, the row of " i " represent pixel array, the row of " j " represent pixel array.Trigger transmits the comparative result of SA module 173.

In addition, in Figure 11, Vres has been represented as the actual V that obtains pixel _TAnd will predict V _T(V _TM) stride that adds/deduct, the minimizing gain of A representative prediction stride, and the increase gain of K representative prediction stride.

The operation of Figure 11 is except having the additional state L2 and G2 that increases for the rapid extraction sudden change, and is identical with the operation of Figure 10.In gain-state, increase step size, to catch up with variation more apace.L1 and G1 limit V _TBe the sudden change or the transformation form of normal variation.

Figure 12 shows an example of the waveform on the pixel 160 that is applied to Fig. 8.In Figure 12, V _Call=V _B+ V _TM, V _DR=V _P+ V _T(i, j)+V _REF, V wherein _BRepresent the bias voltage in the extracting cycle, V _TMBe based on that the algorithm shown in Figure 10 or 11 defines, V _PRepresent program voltage, V _T(i j) represents the threshold voltage that extracts, V in last extracting cycle _REFRepresent the source voltage of the driving transistors in the programming cycle.

With reference to figure 8-12, the operation of image element circuit 160 comprises operating cycle X51, X52, X53 and X54.In Figure 12, extracting cycle separates with programming cycle.Extracting cycle comprises X51 and 52X, and programming cycle comprises X53.X54 is a drive cycle.When programming cycle finishes, make node A3 be charged to (V _P+ V _T), V wherein _PBe program voltage, V _TIt is the threshold voltage of driving transistors 163.

Be in high level at the first operating cycle X51:SEL1 and SEL2.Make node A3 be charged to V _Cal, make node B3 be charged to V _REFV _CalBe V _B+ V _TM, V wherein _BBe bias voltage, V _TMV for prediction _T, and V _REFShould be greater than V _DD-V _OLED0, V wherein _OLED0ON voltage for OLED161.

In the second operating cycle X52:SEL1 vanishing.Grid-the source voltage of driving transistors 163 is provided by following formula:

VGS＝V _B+V _TM+ΔV _B+ΔV _TM-ΔV _T2-ΔV _H

Wherein VGS represents the grid-source voltage of driving transistors 163, Δ V _B, Δ V _TM, Δ V _T2With Δ V _HBe respectively to depend on V _B, V _TM, V _T2And V _HDynamic effect.V _T2The threshold voltage of representation switch transistor 164, V _HThe change in voltage of SEL1 when second operating cycle of representative when the X52 vanishing begins.

SA module 173 is adjusted to detection greater than β (V _B) ²Electric current so that the grid-source voltage of driving transistors 163 is greater than (V _B+ V _T), wherein β is the gain parameter in the I-V family curve of driving transistors 163.

Therefore, after iteration several times, V _TMAnd pixel (i, extraction threshold voltage V j) _T(i j) focuses on:

V _TM＝V _T-γ.(V _B+V _T+V _T2-V _H)

γ = \frac{C_{g 2} / (2 \cdot C_{S})}{1 + C_{g 2} / (2 \cdot C_{S})}

C wherein _G2The grid capacitance of representation switch transistor 164.

Be in high level at the 3rd operating cycle X53:SEL1.VDATA becomes V _DRNode A3 is charged to [V _P+ V _T(i, j)-γ (V _P-V _B)].

In the 4th operating cycle X54:SEL1 and SEL2 vanishing.Consider dynamic effect, the grid-source voltage of driving transistors 163 can be write as:

VGS＝V _P+V _T

Therefore, pixel current becomes irrelevant with the static state and the dynamic effect of threshold voltage shift.

Among Figure 12, extracting cycle and programming cycle are illustrated as the cycle separately.Yet, also extracting cycle and programming cycle can be merged, as shown in figure 13.Figure 13 shows another example of the waveform of the image element circuit 160 that is applied to Fig. 8.

With reference to figure 8-11 and 13, the operation of image element circuit 160 comprises operating cycle X61, X62 and X63.Programming and extracting cycle are merged into operating cycle X61 and X62.Operating cycle X63 is a drive cycle.

In programming cycle, pixel current and the electric current that needs are compared, extract the threshold voltage of driving transistors with the algorithm of Figure 10 or 11.With the V among the operating cycle X61 _DR=V _P+ V _T(i, j)+V _REFImage element circuit 160 is programmed.Monitor pixel current by the MONITOR line then, and itself and the electric current that needs are compared.The result uses the extraction algorithm of Figure 10 or 11 based on the comparison, upgrades threshold voltage V _T(i, j).

Two selection wire SEL1 and SEL2 have been shown among Fig. 8.Yet, can use the signal selection wire (for example, SEL1) to come operating switch transistor 164 and 165 as public selection wire.When using public selection wire, the SEL1 among Figure 12 remains on high level in the second operating cycle X52, and VGS remains on (V _B+ V _TM).Therefore, detect less than dynamic effect.

Above-mentioned step calibration Driving technique can be applicable to the image element circuit 190 of Figure 14.Image element circuit 190 comprises OLED 191, holding capacitor 192 and driving transistors 193, and switching transistor 194 and 195.Image element circuit 190 is current programmed 3-TFT image element circuits.A plurality of image element circuits 190 can constitute the AMOLED display.

Transistor 193,194 and 195 is n type TFT.Yet transistor 193,194 and 195 also can be the p transistor npn npn.The step calibration Driving technique that is applied to image element circuit 190 also can be applied to the image element circuit that has the p transistor npn npn.Transistor 193,194 and 195 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology (for example, MOSFET) makes.

The gate terminal of driving transistors 193 is connected on the signal wire VDATA by switching transistor 194, is also connected on the holding capacitor 192.The source terminal of driving transistors 193 is connected to the anode electrode of OLED 191, and is connected on the monitoring cable MONITOR by switching transistor 195.The drain electrode end of driving transistors 193 is connected on the voltage supply

line VDD.Transistor

194 and 195 grid section are connected respectively on selection wire SEL1 and the SEL2.

Transistor 193 with 194 and holding capacitor 192 be connected at node A4 place.Transistor 195, OLED 191 and holding capacitor 192 are connected at Node B 4 places.

The structure of image element circuit 190 is except OLED 191 is positioned at the source terminal of driving transistors 193, with structural similarity shown in Figure 8.The operation of image element circuit 190 is identical with the image element circuit shown in Figure 12 or 13.

Owing in extracting cycle (X51 and X52 or X62), make that the source terminal of drive TFT 193 is VREF, data of extracting and source and earthing pop-corn (ground bouncing) are irrelevant.In addition, in programming cycle (X53 or X61), make that the source terminal of drive TFT is V _REF, it is irrelevant with source and earthing pop-corn that the grid-source voltage of drive TFT becomes.Because these situations, pixel current and source and earthing pop-corn are irrelevant.

Figure 15 shows the analog result of step calibration Driving technique.In Figure 15, the operation of the SEL1 in " situation I " representative graph 8 under the situation of second operating cycle (X52 among Figure 12) vanishing; SEL1 in " situation II " representative graph 8 remains on the operation under the situation of high level in second operating cycle.

In Figure 15, Δ V _TRBe driving transistors (for example, Fig. 8 163) threshold voltage can detected smallest offset, Δ V _T2RBe can detected smallest offset in the threshold voltage of switching transistor (for example, Fig. 8 164), and I _PLIt is the pixel current of the pixel in drive cycle.

Because the dynamic effect of threshold voltage shift, for given program voltage, the pixel current of situation II is less than the pixel current of situation I.In addition, the pixel current of situation II increases (a) when the threshold voltage of driving transistors increases, and reduces (b) when the threshold voltage of switching transistor reduces.Yet the pixel current of situation I is stable.The maximum error that causes in the pixel current is less than 0.5% of any skew in the threshold voltage of driving and switching TFT.Significantly, because the V on the pixel current _TThe influence of skew is preponderated, so Δ V _T2RGreater than Δ V _TRThese two parameters are by the resolution (V of driver (for example, 174 of Fig. 9) _s) and the SNR of SA module (for example, 193 of Fig. 9) control.Owing to can not detect less than Δ V _TRSkew, and the time constant of threshold shift is very big, so may carry out extracting cycle (for example, the X51 of Figure 12 and X52) after at interval at the long time that is made of several frames, the lower power consumption of generation like this.Simultaneously, the main operating cycle becomes other programming cycle (for example, the X53 of Figure 12) and drive cycle (for example, the X54 of Figure 12).Therefore, can obviously shorten the programming time, high resolving power is provided, be the large tracts of land AMOLED display of condition precedent with the high speed programming.

Figure 16 shows an example that is used for array of display 200 is carried out the system architecture of step calibration driving.Array of display 200 comprises a plurality of image element circuits (for example, 190 among 160 among Fig. 8 or Figure 14).

Array of display 200 is provided with gate drivers 202, the driver/SA module 204 that is used to select image element circuit, and, data processing and alignment unit module 206.Driver/SA module 204 comprises driver 174 and the SA module 173 among Fig. 9.Data processing and alignment unit module 206 comprise the DPU module 172 of Fig. 9." calibration " among Figure 16 comprises the calibration data from calibration storage 208, and can comprise the constant that the certain user defines, and is used to set calibration data and handles.The user uses contrast and brightness input to regulate the contrast and the brightness of panel.In addition, define the Gamma correction data based on OLED family curve and human eye.Use Gamma correction to import the pixel intensity of regulating for human eye.

The extraction threshold voltage V of calibration storage 208 each pixel of storage _T(i, j) and state s (i, j).Storer 210 is stored the data that other needs for the normal running of display, comprises Gamma correction, resolution, contrast etc.The DPU module is carried out the controller distribute in the display and the normal tasks of scheduler.In addition, the algorithm that increases Figure 10 or 11 is carried out calibration.

Figure 17 shows an example of the waveform of the system architecture that is applied to Figure 16.In Figure 17, ROW[1], ROW[2], ROW[3] in each represent row in the array of display 200, operation is extracted in " E " representative, " P " represent programming operation, and " D " representative drives and operates.It should be noted that the not all frame period all needs to carry out extracting cycle (E).Therefore, (extract the interval) at interval at long time and afterwards, repeat extraction pixel.

As shown in figure 17, extraction procedure only takes place in the time of a frame one time.In addition, the VT that carries out simultaneously the image element circuit on going together mutually extracts.

Therefore, upgrading a frame required maximum time is:

τ _F＝n·τ _p+τ _E

τ wherein _FThe representative frame time, τ _pRepresentative writes required time in the holding capacitor (for example, Fig. 8 162), τ with pixel data _ERepresent extraction time, n represents the line number in the array of display (for example, 200 of Figure 16).

Suppose τ _E=m τ _p, frame time τ _FCan be written as:

τ _F＝(n+m)·τ _P

Wherein the m representative is at programming cycle time (τ _p) required time of extracting cycle in the yardstick.

For example, be 1/4th Video Graphics Arrays (QVGA) displays (240 * 320) of 60Hz for frame per second, if m=10, then the programming time of every row is 66 μ s, extraction time is 0.66ms.

Note that above-mentioned step calibration Driving technique can be applicable to any current programmed image element circuit except shown in Fig. 8 and 14.

Utilize the step calibration Driving technique, the time-varying parameter of the pixel of extraction such as threshold shift etc.Then, utilize information extraction to calibrate program voltage, produce stable in time pixel current.And, can be image element circuit and be provided at the steady current that has nothing to do with pixel ageing under the long-time display operation, this has improved the life-span of display operation effectively.

Describe the technology programming, extract the time-varying parameter of pixel and drive pixel of being used to according to another embodiment of the present invention below in detail.This technology comprises by monitoring OLED voltage or OLED electric current to be extracted about pixel ageing (for example, OLED brightness) information, and generation brightness.Utilize information extraction to calibrate program voltage, produce stable in time brightness.

Because known OLED voltage/current and OLED (for example, 161 of Fig. 8, Figure 14 191) luminance degradation relevant, so can change program voltage so that constant brightness to be provided by the OLED voltage/current.

For example, in drive cycle, when SEL2 is in high level, extract the voltage/current of OLED (161 of Fig. 8, Figure 14 191).Because known OLED voltage or electric current are relevant with the luminance degradation of OLED, thus can revise program voltage by OLED voltage, so that constant brightness to be provided.

Figure 18 shows an example of the waveform that is used for the voltage/current extraction.The waveform of Figure 18 can be applicable to the image element circuit 190 of the image element circuit 160 of Fig. 8 and Figure 14 to extract the OLED voltage/current.The operation of Figure 18 comprises operating cycle X71, X72 and X73.Operating cycle X71 and X72 are the OLED extracting cycles.Operating cycle X73 is one of operating cycle shown in Figure 12 and 13.

In the first operating cycle X71, SEL1 and SEL2 are in high level, and VDATA is zero.Grid-source voltage the vanishing of driving transistors (for example, 163 of Fig. 8).Curtage is applied to OLED (Fig. 8 161) by the MONITOR line.

In the second operating cycle X72, SEL2 is in high level, and SEL1 is in low level.Use the algorithm shown in Figure 10 or 11, extract OLED voltage or electric current by the MONITOR line.This waveform and any other drive waveforms can be made up.

In the foregoing description, result's (electric current and curtage and voltage) uses the algorithm among Figure 10 and Figure 11 to predict aging data based on the comparison, that is, and and V _TSkew.Yet, by using V _OLEDReplace V _TWith the comparative result of OLED current/voltage and reference current/voltage, can use the algorithm of Figure 10 and Figure 11 and predict OLED voltage V _OLEDSkew.In the foregoing description, use system architecture shown in Figure 9 to compensate threshold shift.However, it should be understood that and using structure shown in Figure 9, that is, when DPU 172, module 173, driver 174 etc., also extract the OLED data.Can use these data to compensate the OLED skew.

Operating cycle X73 can be any operating cycle that comprises programming cycle.This depends on that OLED extracts panel state afterwards.If it is in the operating process, then X73 is the programming cycle of the waveform among Figure 12 and Figure 13.Can in the drive cycle X55/X63 of Figure 12/13, extract OLED voltage.Therefore in drive cycle X55/X63, the SEL2 among Fig. 8 or Figure 14 becomes high pressure, can be by the read back voltage of OLED of specific pixel electric current of MONITOR.

Figure 19 shows another example of the waveform that is used for the voltage/current extraction.Figure 20 shows the image element circuit 220 of the voltage/current extraction of using Figure 19.

With reference to Figure 20, image element circuit 220 comprises OLED 221, holding capacitor 222 and driving transistors 223 and switching transistor 224 and 225.A plurality of image element circuits 220 can constitute the AMOLED display.

Transistor the 223,224, the 225th, n type TFT, however transistor 223,224,225 also can be p type TFT.The voltage/current extractive technique that is applied to image element circuit 220 also can be applicable to have the image element circuit of p transistor npn npn.Transistor 223,224,225 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology (for example, MOSFET) makes.

The gate terminal of driving transistors 223 is connected to the source terminal of switching transistor 224, is also connected to holding capacitor 222.One end of driving transistors 223 is connected to common ground.The other end of driving transistors 223 is connected to watch-dog and data line MONITOR/DATA by switching transistor 235, is also connected to the cathode electrode of OLED 221.

The gate terminal of switching transistor 224 is connected to selection wire SEL1.One end of switching transistor 224 is connected to the gate terminal of driving transistors 223, and is connected on the holding capacitor 222.The other end of switching transistor 224 is connected to the cathode electrode of OLED 221.

The gate terminal of switching transistor 225 is connected to selection wire SEL2.One end of switching transistor 225 is connected to MONITOR/DATA.The other end of switching transistor 225 is connected to the cathode electrode of driving transistors 223 and OLED 221.The anode electrode of OLED 221 is connected to voltage supplying electrode or vdd line.

Transistor 223,224 is connected at node A5 place with holding capacitor 222.Transistor 223,225 is connected at Node B 5 places with OLED 221.

Image element circuit 220 is similar to the image element circuit 160 of Fig. 8.Yet, in image element circuit 220, use the MONITOR/DATA line to be used for monitoring and programming.

With reference to figure 19-20, the operation of image element circuit 220 comprises operating cycle X81, X82 and X83.

In the first operating cycle X81, SEL1 and SEL2 are in high level, and MONITOR/DATA is zero.Grid-source voltage the vanishing of driving transistors (223 among Fig. 2).

In the second operating cycle X82, OLED applies curtage by the MONITOR/DATA alignment, and extracts its voltage or electric current.As mentioned above, use the algorithm shown in Figure 10 or 11, based on the voltage or the electric current of monitoring, the skew of extracting OLED voltage.This waveform and any drive waveforms can be made up.

Operating cycle X83 can be any operating cycle that comprises programming cycle.This depends on that OLED extracts panel state afterwards.

Can use after any Driving technique is programmed for steady current with image element circuit, in the drive cycle of the image element circuit 220 of Figure 20, extract the OLED voltage/current.In drive cycle, SEL2 becomes high pressure, therefore for the specific pixel electric current, and can be by the read back voltage of OLED of MONOTOR/DATA line.

Figure 21 shows another example of the waveform of voltage/current extractive technique.Figure 22 shows the image element circuit 230 of the voltage/current extraction that can use Figure 21.The waveform of Figure 21 can be applicable to the image element circuit 160 of Fig. 8 equally, to extract the OLED voltage/current.

With reference to Figure 22, image element circuit 230 comprises OLED 231, holding capacitor 232 and driving transistors 233, and switching transistor 234 and 235.A plurality of image element circuits 230 can constitute the AMOLED display.

Transistor the 233,234, the 235th, n type TFT, however transistor 233,234,235 also can be p type TFT.The voltage/current extractive technique that is applied to image element circuit 230 also can be applicable to have the image element circuit of p transistor npn npn.Transistor 233,234,235 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology (for example, MOSFET) makes.

The gate terminal of driving transistors 233 is connected to the source terminal of switching transistor 234, is also connected on the holding capacitor 232.One end of driving transistors 233 is connected to voltage supply line VDD.The other end of driving transistors 233 is connected to watch-dog and data line MONITOR/DATA by switching transistor 235, is also connected to the anode electrode of OLED 231.

The gate terminal of switching transistor 234 is connected to selection wire SEL1.One end of switching transistor 234 is connected to the gate terminal of driving transistors 233, and is connected on the holding capacitor 232.The other end of switching transistor 234 is connected to VDD.

The gate terminal of switching transistor 225 is connected to selection wire SEL2.The other end of switching transistor 235 is connected to MONITOR/DATA.The other end of switching transistor 235 is connected to the anode electrode of driving transistors 233 and OLED 231.The anode electrode of OLED 231 is connected to VDD.

Transistor 233,234 is connected at node A6 place with holding capacitor 232.Transistor 233,235 is connected at Node B 5 places with OLED 231.

Image element circuit 230 is similar to the image element circuit 190 of Figure 14.Yet, in image element circuit 230, use the MONITOR/DATA line to be used for monitoring and programming.

With reference to figure 21-22, the operation of Figure 22 comprises operating cycle X91, X92 and X93.

In the first operating cycle X91, SEL1 and SEL2 are in high level, the VDD vanishing.Grid-source voltage the vanishing of driving transistors (for example, 233 of Figure 21).

In the second operating cycle X92, apply electric current (voltage) by MONITOR/DATA alignment OLED (for example, Figure 21 231), and extract its voltage (electric current).As mentioned above, use the algorithm shown in Figure 10 or 11, based on the voltage or the electric current of monitoring, the skew of extracting OLED voltage.This waveform and any drive waveforms can be made up.

Operating cycle X93 can be any operating cycle that comprises programming cycle.This depends on that OLED extracts panel state afterwards.

Can use after any Driving technique is programmed for steady current with image element circuit, in the drive cycle of the image element circuit 230 of Figure 21, extract OLED voltage.In drive cycle, SEL2 becomes high pressure, therefore for the specific pixel electric current, and can be by the read back voltage of OLED of MONOTOR/DATA line.

Known, under negative bias stress, the OLED family curve is improved.Therefore, from the historical relevant negative bias of OLED voltage/current STRESS VARIATION that extract and pixel, can in the time of operation, not be applied to OLED at display.Any image element circuit that this paper provides can use this method.

Use OLED voltage/current extractive technique, image element circuit can be provided in the stable brightness that has nothing to do with pixel ageing under the long-time display operation, to improve the life-span of display operation effectively.

Describe the unnecessary luminous technology that is used for reducing array of display according to an embodiment of the invention below in detail with luminescent device.This technology is included in the programming cycle to be removed OLED from program path.Can in the combination drive technology, adopt this technology, extract about the pixel information of aging conditions accurately, for example, the actual threshold voltage skew/mismatch of driving transistors.In programming/calibration cycle, close luminescent device, to prevent the unnecessary luminous and influence relevant that prevents luminescent device with pixel ageing.This technology can be applicable to use any current mirror pixel circuit of any technology manufacturing that comprises polysilicon, amorphous silicon, crystalline silicon and organic material.

Figure 23 shows the image element circuit 250 based on mirror image of having used the technology of in programming cycle OLED being removed from program path.Image element circuit 250 comprises OLED 251, holding capacitor 252 and programming transistor 253, driving transistors 254, and switching transistor 255 and 256.

Transistor

253 and 254 gate terminal are connected to IDATA by switching

transistor

255 and 256.

Transistor 253,254,255 and 256 is n type TFT.Yet transistor 253,254,255 and 256 also can be p type TFT.The OLED removal technology that is applied to image element circuit 250 also can be applicable to have the image element circuit of p transistor npn npn.Transistor 253,254,255 and 256 can use amorphous silicon, receive crystal silicon/microcrystal silicon, polysilicon, organic semiconductor technology (for example, organic tft), NMOS/PMOS technology or CMOS technology (for example, MOSFET) makes.

Transistor 253,254,256 is connected at node A10 place with holding capacitor 252.Transistor 253,254, OLED 251 and holding capacitor 252 are connected at Node B 10 places.

In routine current programmed, SEL becomes high level, and program current (IP) is applied in to IDATA.The width of considering mirrored transistor 253 is (m+1) IP so flow through the electric current of OLED 251 in programming cycle than the width big " m " of mirrored transistor 254 doubly.When " m " is very big when obtaining obvious speed and improve, then unnecessary luminously just may become very important.

On the contrary, remove technology, make VDD enter low-voltage according to OLED.Can guarantee like this to remove OLED 251, as shown in figure 24 from program path.

In programming cycle, SEL is in high level, and VDD becomes reference voltage (Vref), and wherein OLED 251 is reverse biased.Therefore, in programming cycle, OLED 251 is removed from current path.

In programming cycle, can programme to image element circuit 250 with proportional electric current by IDATA, and can not experience unnecessary luminous.

In programming cycle, can utilize electric current and use a kind of above-mentioned technology that image element circuit 250 is programmed.The read back voltage of IDATA line is to extract the threshold voltage of the mirrored transistor 253 identical with the threshold voltage of driving transistors 254.

In addition, in programming cycle, can utilize voltage and use a kind of above-mentioned technology that image element circuit 250 is programmed by the IDATA line.The read back electric current of IDATA line is to extract the threshold voltage of the mirrored transistor 253 identical with the threshold voltage of driving transistors 254.

Selection reference voltage Vref so that the voltage at Node B 10 places become less than the ON voltage of OLED 251.Therefore, OLED 251 closes, unnecessary luminous be zero.The voltage of IDATA line comprises:

V _P+V _T+ΔVT...(3)

V wherein _PComprise the drain-source voltage of driving transistors 254 and the grid-source voltage of transistor 253, V _TBe the threshold voltage of transistor 253 (254), Δ VT is V _TSkew/mismatch.

When programming cycle finished, VDD got back to its initial value, so the voltage at Node B 10 places is got back to OLED voltage VOLED.At drive cycle, SEL is in low level.Because switching

transistor

255 and 256 ends, thus the gate terminal voltage of transistor 254/253 be fix and be stored in the holding capacitor 252.Therefore, in drive cycle, pixel current becomes and threshold voltage V _TIrrelevant.

Can in the combination drive technology, adopt OLED to remove technology, to extract V _TSkew or V _TMismatch.From (3) as can be seen, if utilize electric current that pixel is programmed, then unique variable element is V in the voltage of IDATA line _TSkew/mismatch (Δ V _T).Therefore, can extract Δ V _TAnd can use Δ V _TProgramming data is calibrated.

Figure 25 shows an example of the system architecture that is used to carry out OLED removal technology.Array of display 260 comprises a plurality of image element circuits, for example, and the image element circuit 250 of Figure 26.The operation of display controller and 262 pairs of array of display 260 of scheduler is controlled and is dispatched.Driver 264 provides operating voltage for image element circuit.Driver is based on the instructions/commands from display controller and scheduler 262, for image element circuit provides operating voltage, so that OLED is removed from the program path of image element circuit, as mentioned above.

Controller and scheduler 262 can comprise the function of display controller and the scheduler 64 of Fig. 3, perhaps can comprise the data processing of Figure 16 and the function of alignment unit 206.System shown in Figure 25 can have these functions, and above-mentioned calibration-scheduling, above-mentioned voltage/current extracts or their combination among any function.

Illustrated among Figure 26 and be used for different V _TThe IDATA line on the analog result of voltage.With reference to figure 23-26, the voltage of IDATA line comprises the skew of the threshold voltage of transistor 253 and 254.Program current is 1 μ A.

Unnecessary luminous remarkable minimizing can make resolution higher.Simultaneously, can carry out the independent extraction that circuit is aging and luminescent device is aging, this makes and can be calibrated more accurately.

Note that the notion of using compensation circuit, can replace each transistor shown in Fig. 4-8,14,20,21,23 and 24 with the p transistor npn npn.

All references all is bonded to herein as a reference.

Invention has been described to have utilized one or more embodiment.Yet those skilled in the art can be clear, under the situation of the protection scope of the present invention that does not break away from claim and limited, can carry out various changes and modifications to the present invention.

Claims

1. one kind is carried out the method for real time calibration to the array of display with a plurality of image element circuits that are arranged in rows and columns, and may further comprise the steps:

Generate the step of the priority list of pixel, be used for distinguishing the priority ranking of the pixel that is used to calibrate based on video data and last calibration data, use described priority list to select one or more pixels, utilize the electric current higher that selected one or more pixels are programmed than the threshold current that is used to calibrate;

The step of the one or more pixels from described priority list in the select column of the described array of display of selection;

To the step that the pixel in the described select column is programmed, this step is further comprising the steps of:

Monitor the pixel current of described one or more pixels and obtain the step of calibration data;

Upgrade the step of compensation memory based on described calibration data to be used for calibrating;

The step that sorts of priority list to programming next time.

2. the method for claim 1, wherein described step that pixel in the described select column is programmed comprises:

Be the described one or more pixels startup calibration modes in the described select column, and be other pixel startup normal manipulation mode in the described select column.

3. the method for claim 1, wherein described step that the priority list of programming is next time sorted comprises:

Described one or more pixels of just having calibrated are moved on to the end of described priority list.

4. the pixel current of the described one or more pixels of the method for claim 1, wherein described monitoring and obtain the calibration data step and comprise:

To electric current detect and

Described electric current is compared with the expectation electric current.

5. method as claimed in claim 2, wherein, the described step that pixel in the described select column is programmed comprises:

Based on being stored in the calibration data in the described compensation memory and the combination of programming data, the pixel of normal manipulation mode is programmed.

6. the method for claim 1, wherein described step that pixel in the described select column is programmed comprises:

Optionally described select column is connected to watch-dog, described watch-dog is connected with generator, and this watch-dog is used to carry out the step of the pixel current of the described one or more pixels of described monitoring, and this generator is used to carry out the step of described acquisition calibration data.

7. method as claimed in claim 6, wherein, the described step that pixel in the described select column is programmed comprises:

By the voltage data driver the described one or more pixels in the described select column are programmed.

8. method as claimed in claim 2, wherein,

When starting described calibration mode, optionally described select column is connected to watch-dog, described watch-dog is connected with generator, this watch-dog is used to carry out the step of the pixel current of the described one or more pixels of described monitoring, and this generator is used to carry out the step of described acquisition calibration data.

9. method as claimed in claim 2, wherein, the described step that pixel in the described select column is programmed comprises:

Based on being stored in the calibration data in the described compensation memory and the combination of programming data, other pixel of normal manipulation mode is programmed.

10. method as claimed in claim 9, wherein, the described step that other pixel of normal manipulation mode is programmed comprises:

Based on described calibration data to the voltage data driver provide input and

Other pixel of described normal manipulation mode is connected to described data driver.

11. a system that is used for the array of display with a plurality of image element circuits that are arranged in rows and columns is carried out real time calibration, each image element circuit has luminescent device and driving transistors, and described system comprises:

The calibration schedules device is used to control the programming and the calibration of described array of display, comprising:

Priority list is used for listing one or more pixels that are used to calibrate based on video data;

Being used in programming cycle is one or more pixels startup calibration modes in the select column of selecting from described priority list and the module that starts normal manipulation mode in described programming cycle for the residual pixel in the described select column;

Watch-dog is used to monitor the pixel current of the pixel under the calibration mode on the described select column;

Generator is used for producing calibration data based on monitored results;

Storer is used to store calibration data; With

Regulator is used for regulating the programming data that is applied to described array of display based on described calibration data when the pixel of normal manipulation mode is programmed.

12. system as claimed in claim 11, wherein, described watch-dog comprises the sensor of the electric current that is used to detect voltage form, be used for programming data with current forms become expectation voltage data transducer and be used for the comparer that the voltage data with detected voltage and expectation compares.

13. system as claimed in claim 12, wherein, described image element circuit is current programmed image element circuit.

14. system as claimed in claim 12, wherein, described array of display is connected with the voltage data driver, and the input of described voltage data driver is based on the calibration data that is stored in the described storer and changes.

15. system as claimed in claim 12, wherein, described watch-dog comprises switch, and described switch is used for optionally described select column being connected to described sensor.

16. system as claimed in claim 14, wherein, described watch-dog comprises switch, and described switch is used for optionally pixel under the calibration mode or the pixel under the normal manipulation mode being connected to described voltage data driver.

17. system as claimed in claim 11 comprises:

The voltage data driver is used for described one or more pixels of described select column are programmed.

18. as each described system among the claim 10-17, wherein, described array of display is the AMOLED array.

19. as each described system among the claim 10-17, wherein, described luminescent device is an Organic Light Emitting Diode.

20. as each described system among the claim 10-17, wherein, at least one transistor is a thin film transistor (TFT).

21. as each described system among the claim 11-16, wherein, the transistor of described image element circuit is n type or p type TFT.