CN203982747U - The image element circuit of active organic electroluminescent display - Google Patents

Abstract

The utility model discloses a kind of image element circuit of active organic electroluminescent display, image element circuit is arranged on the signal wire part place intersected with each other that the sweep trace of the row of control signal form is provided and the row form of data-signal is provided, and has comprised the first switching transistor, second switch transistor, the 3rd switching transistor, the 4th switching transistor, the 5th switching transistor, driving transistors, Organic Light Emitting Diode, the first electric capacity and the second electric capacity; This image element circuit can compensation for drive transistor threshold voltage shift (comprising positive threshold voltage and negative threshold voltage), and taked control signal multiplexing between the pixel for adjacent several row, thereby reduced the quantity of control signal wire, reduced the requirement to peripheral driver, thereby reduce the cost, and can realize programming mode at a high speed, make it to be applicable to large scale, high-resolution demonstration.

Description

The image element circuit of active organic electroluminescent display

Technical field

The utility model relates generally to the pixel driver technology of active organic electroluminescent display, is specifically related to the image element circuit of active organic electroluminescent display.

Background technology

Active matrix organic light emitting diode display (Active Matrix Organic Light Emitting Diode:AMOLED) is a kind of emerging flat panel display, because its preparation technology is simple, cost is low, fast response time, low in energy consumption, luminosity is high, working temperature wide accommodation, volume is frivolous and be easy to realize flexible demonstration and the advantage such as large-size screen monitors demonstration, there are wide market outlook, in flat pannel display field, be subject to the extensive attention of scientist and industrial community.

AMOLED image element circuit is pressed the difference of data-signal, can be divided into voltage-type driving circuit and current-driven circuit.Yet, because current type drives the signal delay phenomenon of image element circuit remarkable, and still there is no so far very effective solution, so the research for AMOLED image element circuit at present still lays particular emphasis on voltage driving mode.Voltage driving mode is by the two ends of the direct load store electric capacity of voltage, can greatly reduce the duration of charging of electric capacity, improves its response speed.The image element circuit of traditional voltage driving mode as shown in Figure 1, the advantage of this circuit is to control simple, speed is fast, for these two advantages, it is the design object of all image element circuits, but due to the demonstration unevenness that threshold voltage shift and the OLED performance degradation of driving tube TFT causes AMOLED brightness, this also just makes traditional 2T1C image element circuit be difficult to meet the requirement that present situation AMOLED shows.

In AMOLED image element circuit, generally all comprise a plurality of thin film transistor (TFT)s (TFT), the TFT that is applied at present AMOLED has amorphous silicon film transistor (a-Si TFT), polycrystalline SiTFT (poly-SiTFT) and metal oxide thin-film transistor (MOTFT).And MOTFT compares first two TFT, its mobility is relatively high, simultaneously manufacture craft simple (4-6 photoetching), homogeneity are good, can meet the needs that large scale AMOLED shows, particularly the manufacturing equipment of metal oxide TFT and existing a-SiTFT equipment compatibility are high, preparation 3D and sharpness screen are had to market outlook, enjoy industry to pay close attention to.Certainly, the threshold voltage of these three kinds of TFT all can drift about along with the migration of time, thereby causes corresponding impact to flowing through the electric current of OLED in each pixel, and the luminosity of each pixel also changes, display effect variation.

Be directed to the threshold voltage shift of driving tube TFT and the threshold voltage shift of OLED, many image element circuits with threshold voltage compensation function are suggested.The threshold voltage that these image element circuits obtain driving transistors roughly can be divided into two classes, a kind of is that the grid of driving transistors is connected with drain electrode, first the grid of driving transistors is arranged to a larger voltage (being greater than the threshold V T H of driving transistors), then the grid of driving transistors is suspended (as shown in Fig. 2 (a)), by such structure, the grid voltage of driving transistors will be by discharging between source-drain electrode, until grid voltage reaches the size of its threshold voltage, at this moment driving transistors is closed, and its threshold voltage is also acquired at grid; Another kind method is, by the grid at driving tube, with drain electrode, add different voltage, source electrode suspension (as shown in Fig. 2 (b)), by such structure, the voltage of source electrode will increase gradually, until grid reaches the threshold voltage of driving transistors with the voltage difference between source electrode, thereby the threshold voltage of driving transistors has been latched between the grid source electrode of driving transistors.For first method, be merely able to be adapted to the situation that the threshold voltage of driving transistors is greater than zero, and helpless for the minus situation of threshold voltage of driving transistors.And second method, the threshold voltage that not only can be adapted to driving transistors is positive situation, the threshold voltage that also can be adapted to driving transistors is negative situation, so to take the integrated display of metal oxide TFT that threshold voltage is negative value very applicable at present very popular for this kind of method.

At present, display all tends to high resolving power, large scale shows, the program speed of image element circuit has been proposed to new requirement, traditional 2T1C image element circuit just has very fast program speed, and add the extra TFT of the threshold voltage that some can use compensation for drive transistor on the basis of 2T1C image element circuit after, its program speed is corresponding slack-off (extra increase initialization, these two stages of threshold voltage compensation) also, so the program speed of traditional image element circuit with compensate function is all not suitable with demonstration demand for development of today.Certainly also there is at present corresponding type of drive to be used to high resolving power, during large scale demonstration and 3D show, for example parallel processing scheme (parallel addressing schemes) (is shown in G.Reza Chaji and Arokia Nathan, " Parallel Addressing Scheme for Voltage-Programmed Active-Matrix OLED Displays " IEEE TRANSACTION ON ELECTRON DEVICE, VOL.54, NO.5, MAY 2007), Fig. 3 is the sequential chart of parallel processing plan, in figure: initial phase I, threshold voltage latch stage C, data load phase D, glow phase E.These driving methods all can reach the speed of 2T1C image element circuit substantially, can substantially meet current high resolving power, large-sized needs.Although above-mentioned method can reach the speed of 2T1C image element circuit, but simple this advantage of control for 2T1C image element circuit, these image element circuits are not well positioned to meet, because above-mentioned image element circuit all needs at least 2 above control signals, peripheral driving chip is required to become higher, also increased the wiring difficulty between image element circuit.

Utility model content

In order to overcome the above-mentioned shortcoming and deficiency of prior art, the purpose of this utility model is the display drive apparatus that a kind of image element circuit of active organic electroluminescent display is provided and comprises this image element circuit, threshold voltage shift (comprising positive threshold voltage and negative threshold voltage) that can compensation for drive transistor, and taked control signal multiplexing between the pixel for adjacent several row, thereby reduced the quantity of removing control signal wire, reduce the requirement driving peripheral driver, thereby reduce the cost, and can realize programming mode at a high speed, make it to be applicable to large scale, high-resolution demonstration.

The purpose of this utility model is achieved through the following technical solutions:

A kind of image element circuit of active organic electroluminescent display, be arranged on the signal wire part place intersected with each other that the sweep trace of the row of control signal form is provided and the row form of data-signal is provided, comprise the first switching transistor, second switch transistor, the 3rd switching transistor, the 4th switching transistor, the 5th switching transistor, driving transistors, Organic Light Emitting Diode, the first electric capacity and the second electric capacity;

The drain electrode connection data line of described the first switching transistor, the source electrode of the first switching transistor connects the first pole plate of the first electric capacity;

The transistorized drain electrode of described second switch connects the first pole plate of the first electric capacity, and the transistorized source electrode of second switch connects a reference voltage;

The drain electrode of described the 3rd switching transistor is connected with the negative electrode of OLED, and the source electrode of the 3rd switching transistor connects the drain electrode of driving transistors;

The drain electrode of described the 4th switching transistor connects the source electrode of driving transistors, the source ground of the 4th switching transistor;

The drain electrode of described the 5th switching transistor connects the second pole plate of the first electric capacity, the source ground of the 5th switching transistor;

The drain electrode of described driving transistors connects the source electrode of the 3rd switching transistor, and the source electrode of driving transistors connects the drain electrode of the 4th switching transistor, and the grid of driving transistors connects the first pole plate of the first electric capacity;

Described the second electric capacity has connected the second pole plate of the first electric capacity and the source electrode of driving transistors;

The anode of described Organic Light Emitting Diode connects power supply.

Preferably, also comprise the first to the 5th sweep signal control line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the second scan signal line, the voltage of the grid of the 3rd switching transistor is controlled by the 3rd scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the 4th scan signal line, and the voltage of the grid of the 5th switching transistor is controlled by the 5th scan signal line.

Preferably, first of every a line image element circuit the grid to the 5th switching transistor is controlled by the current line of driving governor institute output signal.

Preferably, also comprise first to fourth scan signal line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the second scan signal line, the voltage of the grid of the 3rd switching transistor is controlled by the 3rd scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the 4th scan signal line, and the voltage of the grid of the 5th switching transistor is controlled by the second scan signal line.

Preferably, the grid of first to fourth switching transistor of its every a line image element circuit is controlled by the current line of driving governor institute output signal; And the grid of the 5th switching transistor is controlled by rear a line signal of the second driving governor institute output signal.

Preferably, also comprise the first scan signal line and the second scan signal line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the first scan signal line also, the voltage of the grid of the 3rd switching transistor is controlled by the second scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the second scan signal line also, and the voltage of the grid of the 5th switching transistor is controlled by the first scan signal line.

Preferably, second of every a line image element circuit, the grid of the 4th switching transistor is controlled by the current line of driving governor institute output signal; And the grid of the first transistor is controlled by the capable institute of rear 1+i of the first scanner driver institute output signal, the 3rd transistorized grid is controlled by the capable institute of rear i of the second scanner driver institute output signal, the 5th transistorized grid is controlled by rear a line of the first scanner driver institute output signal, wherein the time of time/data load phase of i=threshold voltage latch stage.

The utility model has following advantage and effect with respect to prior art:

1, the threshold voltage that the image element circuit of active el display device of the present utility model not only can be positive driving transistors to threshold voltage compensates (for example traditional amorphous silicon film transistor (a-Si TFT) and polycrystalline SiTFT (poly-Si TFT)), the threshold voltage that can also be negative driving transistors to threshold voltage compensates (very popular metal oxide thin-film transistor (MOTFT) at present for example, its threshold voltage can in 0V left and right).

2, the image element circuit of active organic electroluminescent display of the present utility model, the electric current of the organic electroluminescent LED of its glow phase and the cut-in voltage of organic electroluminescent LED are irrelevant, so the in the situation that this image element circuit being degenerated at organic electroluminescent LED, can keep flowing through the current constant of organic electroluminescent LED.

3, the driving method of the image element circuit of active el display device of the present utility model can adopt parallel processing scheme (parallel addressing schemes) (to see G.Reza Chaji and Arokia Nathan, " Parallel Addressing Scheme for Voltage-Programmed Active-Matrix OLED Displays " IEEE TRANSACTION ON ELECTRON DEVICE, VOL.54, NO.5, MAY 2007), can effectively improve the program speed of image element circuit, make the program speed of this image element circuit can reach the speed that becomes of traditional 2T1C image element circuit, be applicable to current large scale, high-resolution demonstration demand for development.

4, the scan control signal line of the image element circuit of active organic electroluminescent display device of the present utility model can carry out multiplexing, thereby reduce the number of scanner driver or peripheral driver equipment.

Accompanying drawing explanation

Fig. 1 is 2T1C image element circuit figure traditional in background technology.

Fig. 2 (a) and Fig. 2 (b) are the method for two kinds of compensation for drive transistor threshold voltages in background technology.

Fig. 3 is the sequential chart of parallel processing plan in background technology.

Fig. 4 is the display device of the active organic electroluminescent display of embodiment 1 of the present utility model.

Fig. 5 is the image element circuit of the active organic electroluminescent display of embodiment 1 of the present utility model.

Fig. 6 is the driving sequential chart of image element circuit of the active organic electroluminescent display of embodiment 1 of the present utility model.

Fig. 7 is the display device of the active organic electroluminescent display of embodiment 2 of the present utility model.

Fig. 8 is the image element circuit of the active organic electroluminescent display of embodiment 2 of the present utility model.

Fig. 9 is the driving sequential chart of image element circuit of the active organic electroluminescent display of embodiment 2 of the present utility model.

Figure 10 is the display device of the active organic electroluminescent display of embodiment 3 of the present utility model.

Figure 11 is the image element circuit of the active organic electroluminescent display of embodiment 3 of the present utility model.

Figure 12 is the driving sequential chart of image element circuit of the active organic electroluminescent display of embodiment 3 of the present utility model.

Figure 13 is the sequential chart that the scanning monitor in the display device of active organic electroluminescent display of embodiment 3 of the present utility model produces.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the utility model is described in further detail, but embodiment of the present utility model is not limited to this.

Embodiment 1

As shown in Figure 4, the general structure of the display device of the active organic electroluminescent display of the present embodiment 1, in figure: data enter drive V _dATA, the first scanner driver Scan1, the second scanner driver Scan2, the 3rd scanner driver Scan3, the 4th scanner driver Scan4, the 5th scanner driver Scan5.This equipment is substantially by pel array parts Pixel, scanner driver (Scan1, Scan2, Scan3, Scan4, Scan5) and data enter drive.Pel array parts are all connecting with sweep trace Scan1, Scan2, Scan3, Scan4 and the Scan5 of row arrangement, to be listed as the data signal line V of arrangement _dATA, these pel array parts also comprise a plurality of power leads, for providing this pixel operation needed the first electromotive force V _ref, the second electromotive force VSS and the 3rd electromotive force VDD.The needed first electromotive force Vref of operation of pixel is for predetermined electromotive force setting, and the second electromotive force VSS is also for ground connection, and the 3rd electromotive force VDD is for providing power supply to this pixel.

Fig. 5 shows the circuit diagram that is formed on the pel array parts in the display device shown in Fig. 4, in figure: the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, capable the first scan control line Scan1 of n, capable the second scan control line Scan2 of n, capable the 3rd scan control line Scan3 of n, capable the 4th scan control line Scan4 of n, capable the 5th scan control line Scan5 of n, power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.Because the structure of the image element circuit shown in Fig. 2 is used as basis of the present utility model, be therefore described in greater detail below.With reference to Fig. 2, image element circuit comprises the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.And control signal, transistor seconds T2 that the first transistor T1 is in response to corresponding capable the first scan control line Scan1 of n are in response to corresponding capable the second scan control line Scan2 of n, the 3rd transistor T 3 and are in response to corresponding capable the 3rd scan control line Scan3 of n, the 4th transistor T 4 and are in response to corresponding capable the 4th scan control line Scan4 of n, the 5th transistor T 5 and are in response to corresponding capable the 5th scan control line Scan5 of n.

Driving sequential chart as shown in Figure 6, in figure: initial phase I, threshold voltage latch stage C, data load phase D, glow phase E, capable the first scan control line Scan1[n of n], capable the second scan control line Scan2[n of n], capable the 3rd scan control line Scan3[n of n], capable the 4th scan control line Scan4[n of n], capable the 5th scan control line Scan5[n of n], data line V _dATA, the data voltage n-1 that n-1 is capable, the data voltage n that n is capable, the data voltage n+1 that n+1 is capable, the driving method of the image element circuit of the active organic electroluminescent display of the present embodiment, only include the driving sequential of the capable pixel of n, the driving sequential of the pixel of other row is similar, be mainly the scanning drive signal line that n is capable (Scan1[n], Scan2[n], Scan3[n], Scan4[n], Scan5[n]) logical sequence, and image element circuit is under the control of these scan signal lines, completed initialization, threshold voltage latchs, data load and the luminous four-stage of organic light emitting diode, the detailed operation of the image element circuit in each stage is as follows:

(1) initialization: the first scan control line Scan1[n of the capable pixel of n] and the 5th scan control line Scan5[n] giving low level, the first switching transistor T1 and the 5th switch crystal T5 close; Second and third of the capable pixel of n, four scan control lines (Scan2[n], Scan3[n], Scan4[n]) give high level, second and third, the corresponding conducting of four switching transistors (T2, T3, T4); Now, the A point in image element circuit has been configured to reference level Vref, and the voltage that C is ordered has been connected to ground, and the level that has completed to this some is reset.

(2) threshold voltage latch stage: the first scan control line Scan1[n of the capable pixel of n] keep low level, the first switching transistor T1 still keeps closing; Second and third scan control line of the capable pixel of n (Scan2[n], Scan3[n]) keeps high level, and second and third switching transistor (T2, T3) still keeps conducting; The 4th scan control line Scan4[n of the capable pixel of n] by high level, become low level and close the 4th switching transistor T4; The 5th scan control line Scan5[n of the capable pixel of n] by low level, become high level conducting the 5th switching transistor T5; Now, driving transistors T6 is opening, and power vd D will charge to C point, and the voltage that C is ordered is raise gradually, until driving transistors is closed condition, the voltage that now C is ordered is Vref-V _tH, drive the threshold voltage of crystal to be also latched between A, C at 2, and the voltage that B is ordered has been pulled to 0V.The mode latching from thresholds voltage can find out, no matter the threshold voltage of driving transistors T6 be on the occasion of or negative value, the voltage that C is ordered all can rise to Vref-V _tHso this image element circuit can the positive or negative threshold voltage shift of compensation for drive transistor.

(3) data load: the first scan control line Scan1[n of the capable pixel of n] by low level, become high level conducting the first switching transistor T1; Second and third scan control line of the capable pixel of n (Scan2[n], Scan3[n]) becomes low level by high level and closes second and third switching transistor (T2, T3); The 4th scan control line Scan4[n of the capable pixel of n] keep low level, the 4th switching transistor T4 still keeps closing; The 5th scan control line Scan5[n of the capable pixel of n] keep high level, the 5th switching transistor T5 still keeps conducting; Now, data signal line is inputted the data voltage V of the capable pixel of n _dATA, the voltage that A is ordered has been transformed into V by reference level Vref _dATA, complete the capable pixel data voltage of n is loaded, and the voltage that now B order still maintaining 0V, C point voltage also maintains Vref-V accordingly _tH.

(4) Organic Light Emitting Diode is luminous: the first scan control line Scan1[n of the capable pixel of n] by high level, become low level and close the first switching transistor T1; The second scan control line Scan2[n of the capable pixel of n] keep low level, second switch transistor T 2 still keeps closing; Third and fourth scan control line of the capable pixel of n (Scan3[n], Scan4[n]) becomes third and fourth switching transistor of high level conducting (T3, T4) by low level; The 5th scan control line Scan5[n of the capable pixel of n] by high level, become low level and close the 5th switching transistor T5; Now, B point is floating-point status, and its voltage will be followed the change in voltage that C orders and change, and now the voltage of 2 of A, C remains constant, is V _dATA-Vref+V _tHso Organic Light Emitting Diode sends corresponding brightness, and the electric current that flows through Organic Light Emitting Diode is:

$I_{\mathrm{OLED}}=\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{gs}}-V_{\mathrm{th}})}^2$

$\begin{array}{c}=\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{th}}+V_{\mathrm{DATA}}-V_{\mathrm{ref}}-V_{\mathrm{th}})}^2\\ =\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{DATA}}-V_{\mathrm{ref}})}^2\end{array}$

Wherein, V _gsfor the grid of driving transistors T6 and the electric potential difference between source electrode, μ _nfor the carrier mobility of driving transistors T6, C _oXfor the gate insulation layer electric capacity of driving transistors T6, W/L is the breadth length ratio of driving transistors T6, V _dATAfor data voltage, V _thfor the threshold voltage of driving transistors T6, VDD is added supply voltage.As can be seen from the above equation, flow through the electric current of OLED and the threshold voltage V of driving transistors T6 _thirrelevant with the cut-in voltage of Organic Light Emitting Diode, so this image element circuit, the in the situation that of driving transistors voltage drift and Organic Light Emitting Diode degeneration, can keep flowing through the current constant of organic light emitting diode.

Embodiment 2

As shown in Figure 7, the general structure of the display device of the active organic electroluminescent display of the present embodiment 2.This equipment is substantially by pel array parts Pixel, scanner driver (Scan1, Scan2, Scan3, Scan4) and data enter drive.Pel array parts are all connecting with sweep trace Scan1, Scan2, Scan3 and the Scan4 of row arrangement, to be listed as the data signal line V of arrangement _dATA, these pel array parts also comprise a plurality of power leads, for providing this pixel operation needed the first electromotive force V _ref, the second electromotive force VSS and the 3rd electromotive force VDD.The needed first electromotive force Vref of operation of pixel is for predetermined electromotive force setting, and the second electromotive force VSS is also for ground connection, and the 3rd electromotive force VDD is for providing power supply to this pixel.The display device of this display of organic electroluminescence, has only included four scanner drivers, has realized the multiplexing of a driver, thereby has reduced the driving design of display device periphery, has saved corresponding cost.

Fig. 8 shows the circuit diagram that is formed on the pel array parts in the display device shown in Fig. 7, in figure: the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, capable the first scan control line Scan1[n of n], capable the second scan control line Scan2[n of n], capable the 3rd scan control line Scan3[n of n], capable the 4th scan control line Scan4[n of n], capable the second scan control line Scan2[n+1 of n+1], power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.With reference to Fig. 8, image element circuit comprises the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.And the first transistor T1 is in response to corresponding capable the first scan control line Scan1[n of n] control signal, transistor seconds T2 be in response to corresponding capable the second scan control line Scan2[n of n], the 3rd transistor T 3 is in response to corresponding capable the 3rd scan control line Scan3[n of n], the 4th transistor T 4 is in response to corresponding capable the 4th scan control line Scan4[n of n], the 5th transistor T 5 is in response to corresponding capable the second scan control line Scan2[n+1 of n+1].

Sequential chart as shown in Figure 9, in figure: initial phase I, threshold voltage latch stage C, data load phase D, glow phase E; Capable the first scan control line Scan1[n of n], capable the second scan control line Scan2[n of n], capable the 3rd scan control line Scan3[n of n], capable the 4th scan control line Scan4[n of n], capable the 5th scan control line Scan2[n+1 of n+1]; Data line V _dATA, the data voltage n-1 that n-1 is capable, the data voltage n that n is capable, the data voltage n+1 that n+1 is capable.The driving method of the image element circuit of the active organic electroluminescent display of the present embodiment, only include the driving sequential of the capable pixel of n, the driving sequential of the pixel of other row is similar, be mainly the scanning drive signal line that n is capable (Scan1[n], Scan2[n], Scan3[n], Scan4[n]) logical sequence and the capable scanning drive signal line of n+1 (Scan2[n+1]), and image element circuit is under the control of these scan signal lines, completed initialization, threshold voltage latchs, data load and the luminous four-stage of organic light emitting diode, the detailed operation of the image element circuit in each stage is as follows:

(1) initialization: the first scan control line Scan1[n of the capable pixel of n] give low level, the first switching transistor T1 closes; Second and third of the capable pixel of n, four scan control lines (Scan2[n], Scan3[n], Scan4[n]) give high level, second and third, the corresponding conducting of four switching transistors (T2, T3, T4); Now, the second scan control line Scan2[n+1 that n+1 is capable] be low level, the 5th switching transistor T5 closes, and the A point in image element circuit has been configured to reference level Vref, and the voltage that C is ordered has been connected to ground, and the level that has completed to this some is reset.

(2) threshold voltage latch stage: the first scan control line Scan1[n of the capable pixel of n] keep low level, the first switching transistor T1 still keeps closing; Second and third scan control line of the capable pixel of n (Scan2[n], Scan3[n]) keeps high level, and second and third switching transistor (T2, T3) still keeps conducting; The 4th scan control line Scan4[n of the capable pixel of n] by high level, become low level and close the 4th switching transistor T4; The second scan control line Scan2[n+1 of the capable pixel of n+1] by low level, become high level conducting the 5th switching transistor T5; Now, driving transistors T6 is opening, and power vd D will charge to C point, and the voltage that C is ordered is raise gradually, until driving transistors is closed condition, the voltage that now C is ordered is Vref-V _tH, drive the threshold voltage of crystal to be also latched between A, C at 2, and the voltage that B is ordered has been pulled to 0V.The mode latching from thresholds voltage can find out, no matter the threshold voltage of driving transistors T6 be on the occasion of or negative value, the voltage that C is ordered all can rise to Vref-V _tHso this image element circuit can the positive or negative threshold voltage shift of compensation for drive transistor.

(3) data load: the first scan control line Scan1[n of the capable pixel of n] by low level, become high level conducting the first switching transistor T1; Second and third scan control line of the capable pixel of n (Scan2[n], Scan3[n]) becomes low level by high level and closes second and third switching transistor (T2, T3); The 4th scan control line Scan4[n of the capable pixel of n] keep low level, the 4th switching transistor T4 still keeps closing; The second scan control line Scan2[n+1 of the capable pixel of n+1] keep high level, the 5th switching transistor T5 still keeps conducting; Now, data signal line is inputted the data voltage V of the capable pixel of n _dATA, the voltage that A is ordered has been transformed into V by reference level Vref _dATA, complete the capable pixel data voltage of n is loaded, and the voltage that now B order still maintaining 0V, C point voltage also maintains Vref-V accordingly _tH.

(4) Organic Light Emitting Diode is luminous: the first scan control line Scan1[n of the capable pixel of n] by high level, become low level and close the first switching transistor T1; The second scan control line Scan2[n of the capable pixel of n] keep low level, second switch transistor T 2 still keeps closing; Third and fourth scan control line of the capable pixel of n (Scan3[n], Scan4[n]) becomes third and fourth switching transistor of high level conducting (T3, T4) by low level; The second scan control line Scan2[n+1 of the capable pixel of n+1] by high level, become low level and close the 5th switching transistor T5; Now, B point is floating-point status, and its voltage will be followed the change in voltage that C orders and change, and now the voltage of 2 of A, C remains constant, is V _dATA-Vref+V _tHso Organic Light Emitting Diode sends corresponding brightness, and the electric current that flows through Organic Light Emitting Diode is:

$\begin{array}{c}{I}_{\mathrm{OLED}}=\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{gs}}-V_{\mathrm{th}})}^2\\ =\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{th}}+V_{\mathrm{DATA}}-V_{\mathrm{ref}}-V_{\mathrm{th}})}^2\\ =\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{DATA}}-V_{\mathrm{ref}})}^2\end{array}$

Wherein, V _gsfor the grid of driving transistors T6 and the electric potential difference between source electrode, μ _nfor the carrier mobility of driving transistors T6, C _oXfor the gate insulation layer electric capacity of driving transistors T6, W/L is the breadth length ratio of driving transistors T6, V _dATAfor data voltage, V _thfor the threshold voltage of driving transistors T6, VDD is added supply voltage.As can be seen from the above equation, flow through the electric current of OLED and the threshold voltage V of driving transistors T6 _thirrelevant with the cut-in voltage of Organic Light Emitting Diode, so this image element circuit, the in the situation that of driving transistors voltage drift and Organic Light Emitting Diode degeneration, can keep flowing through the current constant of organic light emitting diode.

Embodiment 3

As shown in figure 10, the general structure of the display device of the active organic electroluminescent display of the present embodiment 3.This equipment is substantially by pel array parts Pixel, scanner driver (Scan1, Scan2) and data enter drive.Pel array parts are all connecting the sweep trace Scan1 that arranges with row and Scan2, to be listed as the data signal line V of arrangement _dATA, these pel array parts also comprise a plurality of power leads, for providing this pixel operation needed the first electromotive force V _ref, the second electromotive force VSS and the 3rd electromotive force VDD.The needed first electromotive force Vref of operation of pixel is for predetermined electromotive force setting, and the second electromotive force VSS is also for ground connection, and the 3rd electromotive force VDD is for providing power supply to this pixel.The display device of this display of organic electroluminescence, has only included two scanner drivers, has realized repeatedly multiplexing to these two scanner drivers, thereby has reduced the driving design of display device periphery, has saved corresponding cost.

Figure 11 shows the circuit diagram that is formed on the pel array parts in the display device shown in Figure 10, in figure: the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, capable the first scan control line Scan1[n+4 of n+4], capable the first scan control line Scan1[n of n], capable the second scan control line Scan2[n+3 of n+3], capable the second scan control line Scan2[n of n], capable the 5th scan control line Scan1[n+1 of n+1], power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.With reference to Figure 11, image element circuit comprises the first switching transistor T1, second switch transistor T 2, the 3rd switching transistor T3, the 4th switching transistor T4, the 5th switching transistor T5, driving transistors T6, the first capacitor C 1, the second capacitor C 2, power lead VDD, reference voltage Vref, ground wire VSS, data line V _dATA, Organic Light Emitting Diode OLED.And the first transistor T1 is in response to corresponding capable the first scan control line Scan1[n+4 of n+4] control signal, transistor seconds T2 is in response to corresponding capable the first scan control line Scan1[n of n], the 3rd transistor T 3 is in response to corresponding capable the second scan control line Scan2[n+3 of n+3], the 4th transistor T 4 is in response to corresponding capable the second scan control line Scan2[n of n], the 5th transistor T 5 is in response to corresponding capable the first scan control line Scan1[n+1 of n+1].

Figure 13 is the sequential chart that the scanning monitor in the display device of active organic electroluminescent display of embodiment 3 of the present utility model produces; In figure: the n-1 line scanning control signal Scan1[n-1 that the first sweep signal controller produces], the n line scanning control signal Scan1[n that produces of the first sweep signal controller], the n+1 line scanning control signal Scan1[n+1 that produces of the first sweep signal controller], the n+2 line scanning control signal Scan1[n+2 that produces of the first sweep signal controller]; The n-1 line scanning control signal Scan2[n-1 that the second sweep signal controller produces], the n line scanning control signal Scan2[n that produces of the second sweep signal controller], the n+1 line scanning control signal Scan2[n+1 that produces of the second sweep signal controller], the n+2 line scanning control signal Scan2[n+2 that produces of the second sweep signal controller];

The scan signal line producing according to the first scanner driver and the second scanner driver of Figure 13 obtains the sequential chart of the capable pixel of its n, as shown in figure 12, and in figure: initial phase I, threshold voltage latch stage C, data load phase D, glow phase E, capable the first scan control line Scan1[n+4 of n+4], capable the first scan control line Scan1[n of n], capable the second scan control line Scan2[n+3 of n+3], capable the second scan control line Scan2[n of n], capable the 5th scan control line Scan1[n+1 of n+1], data line V _dATA, the data voltage n-1 that n-1 is capable, the data voltage n that n is capable, the data voltage n+1 that n+1 is capable, the driving method of the image element circuit of the active organic electroluminescent display of the present embodiment (this driving method is the situation while being 3 times of data load phase time in the threshold voltage latch stage time), only include the driving sequential of the capable pixel of n, the driving sequential of the pixel of other row is similar, be mainly n, the first scanning drive signal line that n+1 and n+4 are capable (Scan1[n], Scan1[n+1], Scan1[n+4]) logical sequence and n and capable the second scanning drive signal line of n+3 (Scan2[n], Scan2[n+3]), and image element circuit is under the control of these scan signal lines, completed initialization, threshold voltage latchs, data load and the luminous four-stage of organic light emitting diode, the detailed operation of the image element circuit in each stage is as follows:

(1) the first scan control line Scan1[n that initialization: n is capable] to high level, the corresponding conducting of second switch transistor T 2; The second scan control line Scan2[n that n is capable] to high level, the corresponding conducting of the 4th switching transistor T4; Now, the first scan control line that n+1 and n+4 are capable (Scan1[n+1], Scan1[n+4]) is low level, and the first switching transistor T1 and the 5th switching transistor T5 close; And the second capable scan control line Scan2[n+3 of n+3] be high level, the 3rd switch crystal conducting; A point in image element circuit has been configured to reference level Vref, and the voltage that C is ordered has been connected to ground, and the level that has completed to this some is reset.

(2) the first capable scan control line Scan1[n of threshold voltage latch stage: n] maintain high level, the corresponding conducting of second switch transistor T 2; The second scan control line Scan2[n that n is capable] by high level, become low level to close the 4th switching transistor T4; Now, the first scan control line Scan1[n+1 of n+1] by low level, become high level to close the 5th switching transistor T5, and the first capable scan control line Scan1[n+4 of n+4] still maintaining low level, the first switching transistor T1 is still closed condition; The second scan control line Scan2[n+3 that n+3 is capable] be still high level, the 3rd switch crystal T3 maintains conducting state; Now, driving transistors T6 is opening, and power vd D will charge to C point, and the voltage that C is ordered is raise gradually, until driving transistors is closed condition, the voltage that now C is ordered is Vref-V _tH, drive the threshold voltage of crystal to be also latched between A, C at 2, and the voltage that B is ordered has been pulled to 0V.The mode latching from thresholds voltage can find out, no matter the threshold voltage of driving transistors T6 be on the occasion of or negative value, the voltage that C is ordered all can rise to Vref-V _tHso this image element circuit can the positive or negative threshold voltage shift of compensation for drive transistor.

(3) data load: the first scan control line Scan1[n that n is capable] by high level, become low level to close second switch transistor T 2; The second scan control line Scan2[n that n is capable] maintain low level, the 4th switching transistor T4 still closes; Now, the first scan control line Scan1[n+1 of n+1] maintain high level, the 5th still conducting of switching transistor T5, and the first capable scan control line Scan1[n+4 of n+4] by low level, become high level with conducting the first switching transistor T1; The second scan control line Scan2[n+3 that n+3 is capable] by high level, become low level to close the 3rd switch crystal T3; Now, data signal line is inputted the data voltage V of the capable pixel of n _dATA, the voltage that A is ordered has been transformed into V by reference level Vref _dATA, complete the capable pixel data voltage of n is loaded, and the voltage that now B order still maintaining 0V, C point voltage also maintains Vref-V accordingly _tH.

(4) the second scan control line Scan2[n that idle condition: n is capable] at the first capable scan control line Scan1[n of n] by low level, become high level while becoming low level by high level, this stage continues up to the second scan control line Scan2[n+3 that n+3 is capable] finish while becoming high level by low level.In this stage, the voltage difference that A point and C are ordered will remain constant, be V _dATA-Vref+V _tH.

(5) Organic Light Emitting Diode is luminous: the first scan control line that n, n+1 and n+4 are capable (Scan1[n], Scan1[n+1], Scan1[n+4]) be low level, first and second and five switching transistors (T1, T2 and T5) are closed; The second scan control line that n and n+3 are capable (Scan2[n], Scan2[n+3]) is high level, third and fourth switching transistor (T3, T4) conducting; Now, B point is floating-point status, and its voltage will be followed the change in voltage that C orders and change, and now the voltage of 2 of A, C remains constant, is V _dATA-Vref+V _tHso Organic Light Emitting Diode sends corresponding brightness, and the electric current that flows through Organic Light Emitting Diode is:

$\begin{array}{c}{I}_{\mathrm{OLED}}=\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{gs}}-V_{\mathrm{th}})}^2\\ =\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{th}}+V_{\mathrm{DATA}}-V_{\mathrm{ref}}-V_{\mathrm{th}})}^2\\ =\frac{1}{2}{\mathrm{\μ}}_n\·C_{\mathrm{OX}}\·\frac{W}{L}\·{(V_{\mathrm{DATA}}-V_{\mathrm{ref}})}^2\end{array}$

Wherein, V _gsfor the grid of driving transistors T6 and the electric potential difference between source electrode, μ _nfor the carrier mobility of driving transistors T6, C _oXfor the gate insulation layer electric capacity of driving transistors T6, W/L is the breadth length ratio of driving transistors T6, V _dATAfor data voltage, V _thfor the threshold voltage of driving transistors T6, VDD is added supply voltage.As can be seen from the above equation, flow through the electric current of OLED and the threshold voltage V of driving transistors T6 _thirrelevant with the cut-in voltage of Organic Light Emitting Diode, so this image element circuit, the in the situation that of driving transistors voltage drift and Organic Light Emitting Diode degeneration, can keep flowing through the current constant of organic light emitting diode.

Above-described embodiment is preferably embodiment of the utility model; but embodiment of the present utility model is not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present utility model and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection domain of the present utility model.

Claims (7)

1. the image element circuit of an active organic electroluminescent display, be arranged on the signal wire part place intersected with each other that the sweep trace of the row of control signal form is provided and the row form of data-signal is provided, it is characterized in that, comprise the first switching transistor, second switch transistor, the 3rd switching transistor, the 4th switching transistor, the 5th switching transistor, driving transistors, Organic Light Emitting Diode, the first electric capacity and the second electric capacity;

The drain electrode connection data signal wire of described the first switching transistor, the source electrode of the first switching transistor connects the first pole plate of the first electric capacity;

The transistorized drain electrode of described second switch connects the first pole plate of the first electric capacity, and the transistorized source electrode of second switch connects a reference voltage;

The drain electrode of described the 3rd switching transistor is connected with the negative electrode of OLED, and the source electrode of the 3rd switching transistor connects the drain electrode of driving transistors;

The drain electrode of described the 4th switching transistor connects the source electrode of driving transistors, the source ground of the 4th switching transistor;

The drain electrode of described the 5th switching transistor connects the second pole plate of the first electric capacity, the source ground of the 5th switching transistor;

The drain electrode of described driving transistors connects the source electrode of the 3rd switching transistor, and the source electrode of driving transistors connects the drain electrode of the 4th switching transistor, and the grid of driving transistors connects the first pole plate of the first electric capacity;

Described the second electric capacity has connected the second pole plate of the first electric capacity and the source electrode of driving transistors;

The anode of described Organic Light Emitting Diode connects power supply.

2. the image element circuit of active organic electroluminescent display according to claim 1, it is characterized in that, also comprise the first to the 5th sweep signal control line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the second scan signal line, the voltage of the grid of the 3rd switching transistor is controlled by the 3rd scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the 4th scan signal line, the voltage of the grid of the 5th switching transistor is controlled by the 5th scan signal line.

3. the image element circuit of active organic electroluminescent display according to claim 2, is characterized in that, the first grid to the 5th switching transistor of every a line image element circuit is controlled by the current line of driving governor institute output signal.

4. the image element circuit of active organic electroluminescent display according to claim 1, it is characterized in that, also comprise first to fourth scan signal line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the second scan signal line, the voltage of the grid of the 3rd switching transistor is controlled by the 3rd scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the 4th scan signal line, and the voltage of the grid of the 5th switching transistor is controlled by the second scan signal line.

5. the image element circuit of active organic electroluminescent display according to claim 4, is characterized in that, the grid of first to fourth switching transistor of its every a line image element circuit is controlled by the current line of driving governor institute output signal; And the grid of the 5th switching transistor is controlled by rear a line signal of the second driving governor institute output signal.

6. the image element circuit of active organic electroluminescent display according to claim 1, it is characterized in that, also comprise the first scan signal line and the second scan signal line, the voltage of the grid of the first switching transistor is controlled by the first scan signal line, the voltage of the transistorized grid of second switch is controlled by the first scan signal line also, the voltage of the grid of the 3rd switching transistor is controlled by the second scan signal line, the voltage of the grid of the 4th switching transistor is controlled by the second scan signal line also, the voltage of the grid of the 5th switching transistor is controlled by the first scan signal line.

7. the image element circuit of active organic electroluminescent display according to claim 6, is characterized in that, every a line image element circuit second, the grid of the 4th switching transistor controlled by the current line of driving governor institute output signal; And the grid of the first transistor is controlled by the capable institute of rear 1+i of the first scanner driver institute output signal, the 3rd transistorized grid is controlled by the capable institute of rear i of the second scanner driver institute output signal, the 5th transistorized grid is controlled by rear a line of the first scanner driver institute output signal, and wherein i is the ratio of the time of threshold voltage latch stage and the time of data load phase.