CN104008726A - Pixel circuit of active organic electroluminescence displayer and driving method of pixel circuit - Google Patents

Abstract

The invention discloses a pixel circuit of an active organic electroluminescence display and a driving method thereof. The pixel circuit is arranged at a part where row-form scanning lines providing control signals and column-form signal lines providing data signals cross each other. It includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a driving transistor, an organic light emitting diode, a first capacitor and a second capacitor; the pixel circuit can compensate the threshold voltage drift of the driving transistor (including Positive threshold voltage and negative threshold voltage), and control signal multiplexing is adopted between adjacent rows of pixels, thereby reducing the number of control signal lines, reducing the requirements for peripheral drivers, thereby reducing costs, and A high-speed programming method can be realized, making it suitable for large-size, high-resolution displays.

Description

Pixel circuit and driving method of active organic electroluminescence display

technical field

The invention mainly relates to a pixel driving technology of an active organic electroluminescent display, and in particular to a pixel circuit of an active organic electroluminescent display and a driving method thereof.

Background technique

Active Matrix Organic Light Emitting Diode (Active Matrix Organic Light Emitting Diode: AMOLED) is an emerging flat panel display technology. Wide, light and thin, and easy to realize flexible display and large-screen display, etc., have broad market prospects, and are widely valued by scientists and industries in the field of flat panel display.

AMOLED pixel circuits can be divided into voltage-driven circuits and current-driven circuits according to different data signals. However, since the signal delay phenomenon of the current driving pixel circuit is significant, and there is still no very effective solution so far, the current research on the AMOLED pixel circuit still focuses on the voltage driving method. The voltage driving method is to directly load the voltage on both ends of the storage capacitor, which can greatly reduce the charging time of the capacitor and improve its response speed. The pixel circuit of the traditional voltage driving method is shown in Figure 1. The advantage of this circuit is that it is easy to control and fast. For these two advantages, it is the design goal of all pixel circuits. However, due to the threshold voltage drift of the driving tube TFT and OLED The characteristic degradation leads to the display non-uniformity of AMOLED brightness, which makes it difficult for the traditional 2T1C pixel circuit to meet the requirements of the current AMOLED display.

AMOLED pixel circuits generally contain multiple thin-film transistors (TFTs). The TFTs currently used in AMOLEDs include amorphous silicon thin-film transistors (a-Si TFTs), polycrystalline silicon thin-film transistors (poly-SiTFTs) and metal oxide thin-film transistors (MOTFTs). ). Compared with the first two TFTs, MOTFT has relatively high mobility, simple manufacturing process (4-6 photolithography), and good uniformity, which can meet the needs of large-size AMOLED displays, especially the manufacture of metal oxide TFTs. The equipment has high compatibility with existing a-SiTFT equipment, has market prospects for the preparation of 3D and high-resolution displays, and has attracted the attention of the industry. Of course, the threshold voltages of these three types of TFTs will drift with time, which will have a corresponding impact on the current flowing through the OLED in each pixel, and the luminance of each pixel will also change, resulting in poor display effect.

Aiming at the threshold voltage drift of the driving tube TFT and the threshold voltage drift of the OLED, many pixel circuits with a threshold voltage compensation function have been proposed. These pixel circuits can roughly divide the threshold voltage of the drive transistor into two categories. One is to connect the gate of the drive transistor to the drain, and first set the gate of the drive transistor to a relatively large voltage (greater than the threshold voltage of the drive transistor. V _TH ), and then float the gate of the drive transistor (as shown in Figure 2(a)), through such a structure, the gate voltage of the drive transistor will discharge through the source-drain until the gate voltage reaches its threshold At this time, the drive transistor is turned off, and its threshold voltage is also obtained at the gate; another method is to add different voltages to the gate and drain of the drive transistor, and the source is suspended (as shown in Figure 2 ( As shown in b), through such a structure, the voltage of the source will gradually increase until the voltage difference between the gate and the source reaches the threshold voltage of the driving transistor, so that the threshold voltage of the driving transistor is latched into the driving between the gate and source of the transistor. As for the first method, it can only be adapted to the case where the threshold voltage of the driving transistor is greater than zero, but it cannot do anything for the case that the threshold voltage of the driving transistor is less than zero. And the second method can not only be adapted to the situation where the threshold voltage of the driving transistor is positive, but also can be adapted to the situation where the threshold voltage of the driving transistor is negative, so this method is very popular for the current very popular threshold voltage. Displays integrated with metal oxide TFTs are very suitable.

At present, displays tend to display high resolution and large size, which puts forward new requirements for the programming speed of the pixel circuit. The traditional 2T1C pixel circuit has a very fast programming speed, and on the basis of the 2T1C pixel circuit plus some After the additional TFT that compensates the threshold voltage of the driving transistor can be used, its programming speed is correspondingly slowed down (the two stages of initialization and threshold voltage compensation are additionally added), so the programming speed of the traditional pixel circuit with compensation function They are not suitable for today's display development requirements. Of course, there are also corresponding driving methods currently used in high-resolution, large-size displays and 3D displays, such as parallel addressing schemes (see G.Reza Chaji and Arokia Nathan, "Parallel Addressing Scheme for Voltage-Programmed Active- Matrix OLED Displays "IEEE TRANSACTION ON ELECTRONDEVICE, VOL.54, NO.5, MAY2007), Figure 3 is the timing diagram of the parallel processing scheme, in the figure: initialization phase I, threshold voltage latch phase C, data loading phase D, light emission Phase E. These driving methods can basically reach the speed of 2T1C pixel circuits, and can basically meet the current needs of high resolution and large size. Although the above-mentioned method can reach the speed of 2T1C pixel circuit, but for the advantage of simple control of 2T1C pixel circuit, these pixel circuits cannot be well satisfied, because the above-mentioned pixel circuit needs at least two or more control signals. The driver chip requirements become higher, which also increases the difficulty of wiring between pixel circuits.

Contents of the invention

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a pixel circuit of an active organic electroluminescent display and a display driving device including the pixel circuit, which can compensate the threshold voltage drift of the driving transistor (including Positive threshold voltage and negative threshold voltage), and control signal multiplexing is adopted between adjacent rows of pixels, thereby reducing the number of control signal lines and reducing the driver's requirements for peripheral drivers, thereby reducing costs. Moreover, high-speed programming can be realized, making it suitable for large-size, high-resolution displays.

The object of the present invention is achieved through the following technical solutions:

A pixel circuit of an active organic electroluminescence display, which is arranged at a portion where row-form scan lines that provide control signals and column-form signal lines that provide data signals cross each other, including a first switch transistor and a second switch transistor , a third switching transistor, a fourth switching transistor, a driving transistor, an organic light emitting diode, a first capacitor and a second capacitor;

The drain of the first switching transistor is connected to the data line, and the source of the first switching transistor is connected to the first plate of the first capacitor;

The drain of the second switching transistor is connected to the first plate of the first capacitor, and the source of the second switching transistor is connected to a reference voltage;

The drain of the third switching transistor is connected to the cathode of the organic light emitting diode, and the source of the third switching transistor is connected to the drain of the driving transistor;

The drain of the fourth switching transistor is connected to the source of the driving transistor, and the source of the fourth switching transistor is grounded;

The drain of the fifth switching transistor is connected to the second plate of the first capacitor, and the source of the fifth switching transistor is grounded;

The drain of the driving transistor is connected to the source of the third switching transistor, the source of the driving transistor is connected to the drain of the fourth switching transistor, and the gate of the driving transistor is connected to the first plate of the first capacitor;

The second capacitor is connected to the second plate of the first capacitor and the source of the driving transistor;

The anode of the organic light emitting diode is connected to a power source.

Preferably, it also includes first to fifth scanning signal control lines, the voltage of the gate of the first switching transistor is controlled by the first scanning signal line, and the voltage of the gate of the second switching transistor is controlled by the second scanning signal line , the gate voltage of the third switching transistor is controlled by the third scanning signal line, the gate voltage of the fourth switching transistor is controlled by the fourth scanning signal line, and the gate voltage of the fifth switching transistor is controlled by the fifth scanning signal line. controlled by the signal line.

Preferably, the gates of the first to fifth switch transistors of each row of pixel circuits are controlled by the current row of signals output by the drive controller.

Preferably, it also includes first to fourth scanning signal lines, the voltage of the gate of the first switching transistor is controlled by the first scanning signal line, the voltage of the gate of the second switching transistor is controlled by the second scanning signal line, The gate voltage of the third switch transistor is controlled by the third scan signal line, the gate voltage of the fourth switch transistor is controlled by the fourth scan signal line, and the gate voltage of the fifth switch transistor is controlled by the second scan signal line. controlled by the line.

Preferably, the gates of the first to fourth switch transistors of each row of pixel circuits are controlled by the current row of signals output by the drive controller; and the gates of the fifth switch transistor are controlled by the second drive controller. The output signal is controlled by the next row of signals.

Preferably, it also includes a first scanning signal line and a second scanning signal line, the voltage of the gate of the first switching transistor is controlled by the first scanning signal line, and the voltage of the gate of the second switching transistor is also controlled by the first scanning signal line, the voltage of the gate of the third switching transistor is controlled by the second scanning signal line, the voltage of the gate of the fourth switching transistor is also controlled by the second scanning signal line, the voltage of the gate of the fifth switching transistor Controlled by the first scanning signal line.

Preferably, the gates of the second and fourth switch transistors of each row of pixel circuits are controlled by the current row of signals output by the drive controller; and the gates of the first transistors are controlled by the signals output by the first scan driver. Controlled by the last 1+i rows, the gate of the third transistor is controlled by the last i row of the signal output by the second scan driver, and the gate of the fifth transistor is controlled by the last row of the signal output by the first scan driver , where i=time of the threshold voltage latching phase/time of the data loading phase.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for driving a pixel circuit of an active organic electroluminescence display, comprising the steps of:

(1) Initialization: the first scanning control line and the fifth scanning control line of the pixels in the nth row are low, the first switching transistor and the fifth switching transistor are turned off; the second, third and fourth scanning control of the nth row of pixels line to a high level, the second, third, and fourth switching transistors are turned on accordingly; 1≤n≤M, M is the total number of scanning lines of the display;

(2) Threshold voltage latching stage: the first scan control line of the pixels in the nth row keeps low level, and the first switch transistor remains closed; the second and third scan control lines of the pixels in the nth row keep high level, and the first switch transistor remains closed. 2. The third switching transistor remains on; the fourth scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the fourth switching transistor; the fifth scanning control line of the pixels in the nth row changes from a low level to Turning on the fifth switching transistor at a high level; completing latching the threshold voltage of the drive transistor, and the threshold voltage can be positive or negative;

(3) Data loading: the first scan control line of the pixels in the nth row changes from low level to high level to turn on the first switching transistor; the second and third scan control lines of the pixels in the nth row change from high level to Turn off the second and third switching transistors at low level; the fourth scanning control line of pixels in the nth row remains low, and the fourth switching transistor remains closed; the fifth scanning control line of pixels in the nth row remains high, and the The fifth switching transistor remains on; at this time, the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row;

(4) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor; the second scanning control line of the pixels in the nth row maintains a low level, and the second The switching transistor remains closed; the third and fourth scanning control lines of the nth row of pixels change from low level to high level to turn on the third and fourth switching transistors; the fifth scanning control line of the nth row of pixels changes from high level to high level Turning into a low level to turn off the fifth switching transistor; at this time, the organic light emitting diode emits a corresponding brightness according to the loaded data voltage.

As a modification of the above method, the method for driving a pixel circuit of an active organic electroluminescence display includes the following steps:

(1) Initialization: the first scanning control line of the nth row of pixels, the first switching transistor is turned off; the second, third and fourth scanning control lines of the nth row of pixels are high, and the second, third and fourth switching transistors are corresponding Conduction; at this time, the second scanning control line of the n+1th row is low level, and the fifth switching crystal is turned off; 1≤n≤M, M is the total number of scanning lines of the display screen;

(2) Threshold voltage latching stage: the first scan control line of the pixels in the nth row keeps low level, and the first switch transistor remains closed; the second and third scan control lines of the pixels in the nth row keep high level, and the first switch transistor remains closed. The second and third switching transistors still remain on; the fourth scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the fourth switching transistor; at this time, the second scanning control line of the pixels in the n+1th row Turning on the fifth switching transistor from a low level to a high level; completing the threshold voltage latching of the driving transistor, and the threshold voltage can be positive or negative;

(3) Data loading: the first scan control line of the nth row of pixels changes from low level to high level to turn on the first switch transistor; the second and third scan control lines of the nth row of pixels change from high level to Turn off the second and third switching transistors at low level; the fourth scanning control line of pixels in row n keeps low level, and the fourth switching transistor remains closed; the second scanning control line of pixels in row n+1 keeps high level , the fifth switch transistor remains turned on; at this time, the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row;

(4) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor; the second scanning control line of the pixels in the nth row maintains a low level, and the second The switching transistor remains closed; the third and fourth scanning control lines of the nth row of pixels change from low level to high level to turn on the third and fourth switching transistors; the second scanning control line of the n+1th row of pixels changes from high to high level becomes low level to turn off the fifth switching transistor; at this time, the organic light emitting diode emits corresponding brightness according to the loaded data voltage.

As a modification of the above method, the method for driving a pixel circuit of an active organic electroluminescence display includes the following steps:

(1) Initialization: the first scanning control line of the pixels in the nth row is given a high level, and the second switching transistor is turned on; the second scanning control line of the pixels in the nth row is given a high level, and the fourth switching transistor is turned on accordingly; At this time, the first scanning control line of the n+1th row and the n+1+ith row is low level, the first switching transistor and the fifth switching transistor are turned off; the second scanning control line of the n+ith row is low level, the third switch crystal is turned off; 1≤n≤M, M is the total number of scan lines of the display;

(2) Threshold voltage latch stage: the first scan control line of the nth row of pixels maintains a high level, and the second switch transistor remains on; the second scan control line of the nth row of pixels changes from high level to low level, the fourth switching transistor is turned off; at this time, the first scanning control line of the n+1th row of pixels changes from low level to high level, and the fifth switching transistor is turned on; the n+1+ith row of pixels The first scanning control line still maintains a low level, and the first switching transistor is still turned off; the second scanning control line of the n+ith row of pixels still maintains a high level to turn on the third switching transistor; the threshold voltage lock of the driving transistor is completed stored, and the threshold voltage can be positive or negative;

(3) Data loading: the first scanning control line of the pixels in the nth row changes from high level to low level, and the second switching transistor is turned off; the second scanning control line of the pixels in the nth row maintains a low level, and the fourth switch The transistor is still off; at this time, the first scanning control line of the pixels in the n+1th row maintains a high level, and the fifth switch transistor is still turned on; the first scanning control line of the pixels in the n+1+ith row is switched from a low level to becomes high level, the first switching transistor is turned on; the second scanning control line of the n+ith row of pixels changes from high level to low level, and the third switching transistor is turned off; the threshold voltage latch of the driving transistor is completed , and the threshold voltage can be positive or negative; the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row;

(4) Idle state: the first scanning control line of the pixels in the nth row is kept low, and the second switching transistor is kept closed; the second scanning control line of the pixels in the nth row is kept low, and then becomes high level, the fourth switching transistor is kept off first, and then turned on; at this time, the first scanning control line of the n+1th row of pixels changes from high level to low level, and then maintains low level, and the fifth switching transistor is turned off ; The first scanning control line of the n+1+i row of pixels is maintained at a high level, and then becomes a low level, the first switching transistor is kept on and then turned off; the second scan of the n+i row of pixels The control line maintains a low level, and the third switch transistor remains turned off;

(5) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row maintains a low level, and the second switching transistor remains closed; the second scanning control line of the pixels in the nth row maintains a high level, and the fourth switch The transistor remains turned on; at this time, the first scanning control line of the n+1th row of pixels maintains a low level, and the fifth switching transistor is turned off; the first scanning control line of the n+1+ith row of pixels maintains a low level, The first switching transistor remains off; the second scanning control line of the n+ith row of pixels changes from low level to high level, and the third switching transistor is turned on; at this time, the organic light emitting diode emits a corresponding signal according to the loaded data voltage. brightness.

Compared with the prior art, the present invention has the following advantages and effects:

1. The pixel circuit of the active electroluminescence display device of the present invention can not only compensate the threshold voltage of the driving transistor whose threshold voltage is positive (such as the traditional amorphous silicon thin film transistor (a-Si TFT) and polysilicon thin film transistor ( poly-Si TFT)), and can also compensate the threshold voltage of the driving transistor whose threshold voltage is negative (for example, the threshold voltage of the very popular metal oxide thin film transistor (MOTFT) will be around 0V).

2. In the pixel circuit of the active organic electroluminescent display of the present invention, the current of the organic electroluminescent diode in the light-emitting stage has nothing to do with the turn-on voltage of the organic electroluminescent diode, so the pixel circuit is stable when the organic electroluminescent diode is degraded. In this case, the current flowing through the organic light-emitting diode can be kept constant.

3. The driving method of the pixel circuit of the active electroluminescent display device of the present invention can adopt parallel addressing schemes (see G.Reza Chaji and ArokiaNathan, "Parallel Addressing Scheme for Voltage-Programmed Active-Matrix OLED Displays "IEEE TRANSACTION ON ELECTRON DEVICE, VOL.54, NO.5, MAY2007), can effectively improve the programming speed of the pixel circuit, so that the programming speed of the pixel circuit can reach the conversion speed of the traditional 2T1C pixel circuit, suitable for current Large-size, high-resolution display development requirements.

4. The scanning control signal lines of the pixel circuits of the active organic electroluminescent display device of the present invention can be multiplexed, thereby reducing the number of scanning drivers or peripheral driving devices.

Description of drawings

FIG. 1 is a circuit diagram of a conventional 2T1C pixel in the background art.

FIG. 2( a ) and FIG. 2( b ) are two methods for compensating the threshold voltage of the driving transistor in the background art.

FIG. 3 is a timing diagram of a parallel processing scheme in the background art.

FIG. 4 is a display device of an active organic electroluminescence display according to Embodiment 1 of the present invention.

FIG. 5 is a pixel circuit of an active organic electroluminescence display according to Embodiment 1 of the present invention.

FIG. 6 is a driving timing diagram of the pixel circuit of the active organic electroluminescent display according to the first embodiment of the present invention.

FIG. 7 is a display device of an active organic electroluminescent display according to Embodiment 2 of the present invention.

FIG. 8 is a pixel circuit of an active organic electroluminescence display according to Embodiment 2 of the present invention.

FIG. 9 is a driving timing diagram of the pixel circuit of the active organic electroluminescent display according to the second embodiment of the present invention.

FIG. 10 is a display device of an active organic electroluminescent display according to Embodiment 3 of the present invention.

FIG. 11 is a pixel circuit of an active organic electroluminescent display according to Embodiment 3 of the present invention.

FIG. 12 is a driving timing diagram of the pixel circuit of the active organic electroluminescent display according to the third embodiment of the present invention.

FIG. 13 is a timing diagram generated by the scan controller in the display device of the active organic electroluminescent display according to the third embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

As shown in Figure 4, the general structure of the display device of the active organic electroluminescence display of the present embodiment 1, in the figure: data input driver V _DATA , the first scan driver Scan1, the second scan driver Scan2, the third scan driver Scan3, the fourth scan driver Scan4, and the fifth scan driver Scan5. The device basically consists of pixel array part Pixel, scan drivers (Scan1, Scan2, Scan3, Scan4, Scan5) and data input drivers. The pixel array part is connected to the scan lines Scan1, Scan2, Scan3, Scan4 and Scan5 arranged in rows, and the data signal line V _DATA arranged in columns. The pixel array part also includes a plurality of power lines for providing the pixel operation. required first potential V _ref , second potential VSS and third potential VDD. The first potential Vref required for the operation of the pixel is used for a predetermined potential setting, the second potential VSS is also used for grounding, and the third potential VDD is used for supplying power supply to the pixel.

5 is a circuit diagram showing a pixel array component formed on the display device shown in FIG. 4, in which: first switching transistor T1, second switching transistor T2, third switching transistor T3, fourth switching transistor T4, fifth switching transistor Switching transistor T5, driving transistor T6, first capacitor C1, second capacitor C2, the first scan control line Scan1 in the nth row, the second scan control line Scan2 in the nth row, the third scan control line Scan3 in the nth row, the nth row The fourth scan control line Scan4 in the row, the fifth scan control line Scan5 in the nth row, the power supply line VDD, the reference voltage Vref, the ground line VSS, the data line V _DATA , and the organic light emitting diode OLED. Since the structure of the pixel circuit shown in FIG. 2 is used as the basis of the present invention, it will be described in detail below. Referring to FIG. 2, the pixel circuit includes a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5, a driving transistor T6, a first capacitor C1, and a second capacitor C2 , a power line VDD, a reference voltage Vref, a ground line VSS, a data line V _DATA , and an organic light emitting diode OLED. And the first transistor T1 responds to the control signal of the corresponding first scan control line Scan1 in the nth row, the second transistor T2 responds to the corresponding second scan control line Scan2 in the nth row, and the third transistor T3 responds to the corresponding The third scan control line Scan3 in the nth row, the fourth transistor T4 responds to the corresponding fourth scan control line Scan4 in the nth row, and the fifth transistor T5 responds to the corresponding fifth scan control line Scan5 in the nth row.

The driving timing diagram shown in Figure 6, in the figure: initialization phase I, threshold voltage latch phase C, data loading phase D, light emission phase E; the first scanning control line Scan1[n] in the nth row, the nth row The second scanning control line Scan2[n], the third scanning control line Scan3[n] in the nth row, the fourth scanning control line Scan4[n] in the nth row, the fifth scanning control line Scan5[n] in the nth row; data line V _DATA , the data voltage n-1 of the n-1th row, the data voltage n of the nth row, the data voltage n+1 of the n+1th row, the pixel circuit of the active organic electroluminescent display of this embodiment The driving method only includes the driving timing of the pixels in the nth row, and the driving timing of the pixels in other rows is similar, mainly the scanning driving signal lines of the nth row (Scan1[n], Scan2[n], Scan3[n], Scan4[ n], Scan5[n]), and under the control of these scanning signal lines, the pixel circuit completes four stages of initialization, threshold voltage latching, data loading, and organic light-emitting diode light emission. The detailed operation of the pixel circuit is as follows:

(1) Initialization: the first scanning control line Scan1[n] and the fifth scanning control line Scan5[n] of the pixels in the nth row are given a low level, and the first switching transistor T1 and the fifth switching transistor T5 are turned off; the nth row The second, third, and fourth scan control lines (Scan2[n], Scan3[n], Scan4[n]) of the pixel are given a high level, and the second, third, and fourth switching transistors (T2, T3, T4) are turned on accordingly ; At this time, the point A in the pixel circuit is set to the reference level Vref, and the voltage of point C is connected to the ground, and the level reset of these points is completed.

(2) Threshold voltage latch stage: the first scanning control line Scan1[n] of the pixels in the nth row remains at a low level, and the first switching transistor T1 remains closed; the second and third scanning control lines of the pixels in the nth row ( Scan2[n], Scan3[n]) maintain high level, and the second and third switching transistors (T2, T3) remain on; the fourth scanning control line Scan4[n] of the nth row of pixels changes from high level to turn off the fourth switching transistor T4 at a low level; the fifth scanning control line Scan5[n] of the pixels in the nth row changes from a low level to a high level to turn on the fifth switching transistor T5; at this time, the driving transistor T6 is turned on state, the power supply VDD will charge point C, so that the voltage of point C gradually rises until the drive transistor is turned off. At this time, the voltage of point C is Vref-V _TH , and the threshold voltage of the drive crystal is also latched to Between points A and C, and the voltage at point B is pulled to 0V. It can be seen from the threshold voltage latching method above that no matter whether the threshold voltage of the driving transistor T6 is positive or negative, the voltage at point C will rise to Vref-V _TH , so the pixel circuit can compensate for the positive or negative voltage of the driving transistor T6. threshold voltage shift.

(3) Data loading: the first scanning control line Scan1[n] of the nth row of pixels changes from low level to high level to turn on the first switching transistor T1; the second and third scanning control lines of the nth row of pixels ( Scan2[n], Scan3[n]) turn from high level to low level to turn off the second and third switching transistors (T2, T3); the fourth scanning control line Scan4[n] of the nth row of pixels remains low level , the fourth switching transistor T4 is still kept off; the fifth scanning control line Scan5[n] of the pixels in the nth row is kept at a high level, and the fifth switching transistor T5 is still kept on; The data voltage V _DATA , that is, the voltage at point A changes from the reference level Vref to V _DATA , and the pixel data voltage loading of the nth row is completed, and at this time, the voltage at point B remains 0V, and the corresponding voltage at point C also Vref-V _TH is maintained.

(4) Organic light-emitting diodes emit light: the first scan control line Scan1[n] of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor T1; the second scan control line Scan2[n] of the pixels in the nth row n] remains low, and the second switching transistor T2 remains closed; the third and fourth scanning control lines (Scan3[n], Scan4[n]) of the nth row of pixels are turned on from low to high The third and fourth switching transistors (T3, T4); the fifth scanning control line Scan5[n] of the pixels in the nth row changes from high level to low level to close the fifth switching transistor T5; at this time, point B is a floating point state, its voltage will follow the change of the voltage of point C. At this time, the voltage of points A and C remains constant, which is V _DATA -Vref+V _TH , so the organic light-emitting diode emits a corresponding brightness, and flows through the organic light-emitting diode The current is:

$\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; OLED</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; gs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}$

Among them, V _gs is the potential difference between the gate and source of the driving transistor T6, μ _n is the carrier mobility of the driving transistor T6, C _Ox is the gate insulating layer capacitance of the driving transistor T6, and W/L is the driving transistor The aspect ratio of T6, V _DATA is the data voltage, V _th is the threshold voltage of the driving transistor T6, and VDD is the added power supply voltage. It can be seen from the above formula that the current flowing through the OLED has nothing to do with the threshold voltage V _th of the drive transistor T6 and the turn-on voltage of the OLED, so the pixel circuit can maintain The current flowing through the OLED is constant.

Example 2

As shown in FIG. 7 , the general structure of the display device of the active organic electroluminescence display of the second embodiment. The device basically consists of pixel array part Pixel, scan drivers (Scan1, Scan2, Scan3, Scan4) and data input drivers. The pixel array components are connected to the scan lines Scan1, Scan2, Scan3 and Scan4 arranged in rows, and the data signal lines V _DATA arranged in columns. The pixel array components also include a plurality of power lines for providing the pixel operation required The first potential V _ref , the second potential VSS and the third potential VDD. The first potential Vref required for the operation of the pixel is used for a predetermined potential setting, the second potential VSS is also used for grounding, and the third potential VDD is used for supplying power supply to the pixel. The display device of the organic electroluminescence display only includes four scan drivers, which realizes the multiplexing of one driver, thereby reducing the drive design around the display device and saving corresponding costs.

8 is a circuit diagram showing the pixel array components formed on the display device shown in FIG. 7, in which: first switching transistor T1, second switching transistor T2, third switching transistor T3, fourth switching transistor T4, fifth switching transistor Switching transistor T5, driving transistor T6, first capacitor C1, second capacitor C2, the first scan control line Scan1[n] in the nth row, the second scan control line Scan2[n] in the nth row, the third scan in the nth row Control line Scan3[n], fourth scan control line Scan4[n] in row n, second scan control line Scan2[n+1] in row n+1, power supply line VDD, reference voltage Vref, ground wire VSS, data Line V _DATA , Organic Light Emitting Diode OLED. Referring to FIG. 8, the pixel circuit includes a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5, a driving transistor T6, a first capacitor C1, and a second capacitor C2 , a power line VDD, a reference voltage Vref, a ground line VSS, a data line V _DATA , and an organic light emitting diode OLED. And the first transistor T1 responds to the control signal of the corresponding first scan control line Scan1[n] in the nth row, the second transistor T2 responds to the corresponding second scan control line Scan2[n] in the nth row, the third Transistor T3 is in response to the corresponding third scan control line Scan3[n] in the nth row, the fourth transistor T4 is in response to the corresponding fourth scan control line Scan4[n] in the nth row, and the fifth transistor T5 is in response to the corresponding The second scan control line Scan2[n+1] in the n+1th row.

The timing diagram shown in Figure 9, in the figure: initialization phase I, threshold voltage latch phase C, data loading phase D, light emission phase E; the first scan control line Scan1[n] in the nth row, the second in the nth row Scanning control line Scan2[n], third scanning control line Scan3[n] in row n, fourth scanning control line Scan4[n] in row n, fifth scanning control line Scan2[n+1] in row n+1 ; Data line V _DATA , the data voltage n-1 of the n-1th row, the data voltage n of the nth row, and the data voltage n+1 of the n+1th row. The driving method of the pixel circuit of the active organic electroluminescent display in this embodiment only includes the driving timing of the pixels in the nth row, and the driving timings of the pixels in other rows are similar, mainly the scanning driving signal line (Scan1[ n], Scan2[n], Scan3[n], Scan4[n]) and the scanning drive signal line (Scan2[n+1]) of the n+1th row, and the pixel circuit in these scanning signal lines Under the control, four stages of initialization, threshold voltage latching, data loading, and organic light-emitting diode lighting are completed. The detailed operation of the pixel circuit in each stage is as follows:

(1) Initialization: the first scan control line Scan1[n] of the pixels in the nth row is given a low level, and the first switching transistor T1 is turned off; the second, third and fourth scan control lines (Scan2[n] of the pixels in the nth row , Scan3[n], Scan4[n]) to a high level, the second, third, and fourth switching transistors (T2, T3, T4) are turned on accordingly; at this time, the second scanning control line Scan2 of the n+1th row [n+1] is low level, the fifth switching transistor T5 is turned off, the point A in the pixel circuit is set as the reference level Vref, and the voltage of point C is connected to the ground, and the electric voltage of these points is completed. Flat reset.

(2) Threshold voltage latch stage: the first scanning control line Scan1[n] of the pixels in the nth row remains at a low level, and the first switching transistor T1 remains closed; the second and third scanning control lines of the pixels in the nth row ( Scan2[n], Scan3[n]) maintain high level, and the second and third switching transistors (T2, T3) remain on; the fourth scanning control line Scan4[n] of the nth row of pixels changes from high level to The fourth switching transistor T4 is turned off at a low level; the second scanning control line Scan2[n+1] of the n+1th row of pixels changes from a low level to a high level to turn on the fifth switching transistor T5; at this time, the driving Transistor T6 is turned on, and the power supply VDD will charge point C, so that the voltage at point C will gradually increase until the drive transistor is turned off. At this time, the voltage at point C is Vref-V _TH , and the threshold voltage of the drive crystal is also It is latched between points A and C, and the voltage at point B is pulled to 0V. It can be seen from the threshold voltage latching method above that no matter whether the threshold voltage of the driving transistor T6 is positive or negative, the voltage at point C will rise to Vref-V _TH , so the pixel circuit can compensate for the positive or negative voltage of the driving transistor T6. threshold voltage shift.

(3) Data loading: the first scanning control line Scan1[n] of the nth row of pixels changes from low level to high level to turn on the first switching transistor T1; the second and third scanning control lines of the nth row of pixels ( Scan2[n], Scan3[n]) turn from high level to low level to turn off the second and third switching transistors (T2, T3); the fourth scanning control line Scan4[n] of the nth row of pixels remains low level , the fourth switching transistor T4 is still kept off; the second scanning control line Scan2[n+1] of the n+1th row of pixels is kept at a high level, and the fifth switching transistor T5 is still kept on; at this time, the data signal line input The data voltage V _DATA of the pixels in the nth row, that is, the voltage at point A changes from the reference level Vref to V _DATA , and the loading of the pixel data voltage on the nth row is completed, and the voltage at point B remains at 0V at this time, correspondingly The voltage at point C also maintains Vref-V _TH .

(4) Organic light-emitting diodes emit light: the first scan control line Scan1[n] of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor T1; the second scan control line Scan2[n] of the pixels in the nth row n] remains low, and the second switching transistor T2 remains closed; the third and fourth scanning control lines (Scan3[n], Scan4[n]) of the nth row of pixels are turned on from low to high The third and fourth switching transistors (T3, T4); the second scanning control line Scan2[n+1] of the n+1 row pixel turns off the fifth switching transistor T5 from a high level to a low level; at this time, B The point is in a floating point state, and its voltage will follow the voltage change of point C. At this time, the voltage of points A and C remains constant, which is V _DATA -Vref+V _TH , so the organic light-emitting diode emits a corresponding brightness, and the flow The current through the OLED is:

$\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; OLED</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; gs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}$

Among them, V _gs is the potential difference between the gate and source of the driving transistor T6, μ _n is the carrier mobility of the driving transistor T6, C _OX is the gate insulating layer capacitance of the driving transistor T6, and W/L is the driving transistor The aspect ratio of T6, V _DATA is the data voltage, V _th is the threshold voltage of the driving transistor T6, and VDD is the added power supply voltage. It can be seen from the above formula that the current flowing through the OLED has nothing to do with the threshold voltage V _th of the drive transistor T6 and the turn-on voltage of the OLED, so the pixel circuit can maintain The current flowing through the OLED is constant.

Example 3

As shown in FIG. 10 , the general structure of the display device of the active organic electroluminescence display of the third embodiment. The device basically consists of pixel array part Pixel, scan driver (Scan1, Scan2) and data input driver. The pixel array components are connected to the scan lines Scan1 and Scan2 arranged in rows and the data signal lines V _DATA arranged in columns. The pixel array components also include a plurality of power lines for providing the first potential V required for the operation of the pixels. _ref , the second potential VSS and the third potential VDD. The first potential Vref required for the operation of the pixel is used for a predetermined potential setting, the second potential VSS is also used for grounding, and the third potential VDD is used for supplying power supply to the pixel. The display device of the organic electroluminescent display only includes two scan drivers, which realizes the multiplexing of the two scan drivers, thereby reducing the drive design around the display device and saving corresponding costs.

Fig. 11 is a circuit diagram showing the pixel array components formed on the display device shown in Fig. 10, in which: first switching transistor T1, second switching transistor T2, third switching transistor T3, fourth switching transistor T4, Switching transistor T5, driving transistor T6, first capacitor C1, second capacitor C2, the first scan control line Scan1[n+4] in the n+4th row, the first scan control line Scan1[n] in the nth row, the nth row +3 row second scan control line Scan2[n+3], nth row second scan control line Scan2[n], n+1th row fifth scan control line Scan1[n+1], power supply line VDD, reference Voltage Vref, ground wire VSS, data wire V _DATA , organic light emitting diode OLED. Referring to FIG. 11 , the pixel circuit includes a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5, a driving transistor T6, a first capacitor C1, and a second capacitor C2 , a power line VDD, a reference voltage Vref, a ground line VSS, a data line V _DATA , and an organic light emitting diode OLED. And the first transistor T1 responds to the control signal of the corresponding first scanning control line Scan1[n+4] in the n+4th row, and the second transistor T2 responds to the corresponding first scanning control line Scan1[n+4] in the nth row ], the third transistor T3 is in response to the corresponding second scan control line Scan2[n+3] in the n+3th row, the fourth transistor T4 is in response to the corresponding second scan control line Scan2[n] in the nth row, The fifth transistor T5 is responsive to the first scan control line Scan1[n+1] corresponding to the n+1th row.

Fig. 13 is a timing diagram generated by the scan controller in the display device of the active organic electroluminescent display according to Embodiment 3 of the present invention; in the figure: the scan control of the n-1th row generated by the first scan signal controller Signal Scan1[n-1], scan control signal Scan1[n] of line n generated by the first scan signal controller, scan control signal Scan1[n+1 of line n+1 generated by the first scan signal controller ], the scan control signal Scan1[n+2] of the n+2 row generated by the first scan signal controller; the scan control signal Scan2[n-1] of the n-1 row generated by the second scan signal controller, The scanning control signal Scan2[n] of the nth row generated by the second scanning signal controller, the scanning control signal Scan2[n+1] of the n+1th row generated by the second scanning signal controller, and the scanning control signal Scan2[n+1] of the second scanning signal controller The generated scanning control signal Scan2[n+2] of the n+2th row;

According to the scanning signal lines generated by the first scanning driver and the second scanning driver of Figure 13, the timing diagram of the nth row of pixels is obtained, as shown in Figure 12, in the figure: initialization phase I, threshold voltage latching phase C, data Loading stage D, light emitting stage E; the first scanning control line Scan1[n+4] in the n+4th row, the first scanning control line Scan1[n] in the nth row, and the second scanning control line Scan2[ in the n+3th row n+3], the second scan control line Scan2[n] in the nth row, the fifth scan control line Scan1[n+1] in the n+1th row; the data line V _DATA , the data voltage n- in the n-1th row 1, the data voltage n of the nth row, the data voltage n+1 of the n+1th row, the driving method of the pixel circuit of the active organic electroluminescent display of this embodiment (the driving method is in the threshold voltage latch stage time is 3 times of the time in the data loading stage), only including the driving timing of the pixels in the nth row, the driving timing of the pixels in other rows is similar, mainly for the first scan of the nth, n+1 and n+4th rows The logic timing of the driving signal lines (Scan1[n], Scan1[n+1], Scan1[n+4]) and the second scanning driving signal lines (Scan2[n], Scan2[n +3]), and under the control of these scanning signal lines, the pixel circuit completes four stages of initialization, threshold voltage latching, data loading, and organic light-emitting diode light emission. The detailed operation of the pixel circuit in each stage is as follows:

(1) Initialization: the first scan control line Scan1[n] in the nth row is given a high level, and the second switching transistor T2 is turned on accordingly; the second scan control line Scan2[n] in the nth row is given a high level, The fourth switching transistor T4 is correspondingly turned on; at this time, the first scanning control lines (Scan1[n+1], Scan1[n+4]) of the n+1 and n+4th rows are at low level, and the first switch The transistor T1 and the fifth switching transistor T5 are turned off; while the second scanning control line Scan2[n+3] of the n+3th row is at a high level, the third switching transistor is turned on; point A in the pixel circuit is set to The reference level Vref, and the voltage of point C is connected to the ground, and the level reset of these points is completed.

(2) Threshold voltage latch stage: the first scanning control line Scan1[n] in the nth row maintains a high level, and the second switching transistor T2 is turned on accordingly; the second scanning control line Scan2[n] in the nth row is controlled by Change from high level to low level to turn off the fourth switching transistor T4; at this time, the first scanning control line Scan1[n+1] of n+1th changes from low level to high level to turn off the fifth switching transistor T5, while the first scanning control line Scan1[n+4] in the n+4th row still maintains a low level, and the first switching transistor T1 is still in the off state; the second scanning control line Scan2[n in the n+3th row +3] is still at a high level, and the third switching transistor T3 maintains a conduction state; at this time, the drive transistor T6 is in an on state, and the power supply VDD will charge point C, so that the voltage of point C gradually rises until the drive The transistor is in the off state, the voltage at point C is Vref-V _TH at this time, the threshold voltage of the driving crystal is also latched between points A and C, and the voltage at point B is pulled to 0V. It can be seen from the threshold voltage latching method above that no matter whether the threshold voltage of the driving transistor T6 is positive or negative, the voltage at point C will rise to Vref-V _TH , so the pixel circuit can compensate for the positive or negative voltage of the driving transistor T6. threshold voltage shift.

(3) Data loading: the first scanning control line Scan1[n] in the nth row changes from high level to low level to turn off the second switching transistor T2; the second scanning control line Scan2[n] in the nth row maintains low level, the fourth switching transistor T4 is still off; at this time, the n+1th first scan control line Scan1[n+1] maintains a high level, the fifth switching transistor T5 is still on, and the n+4th The first scan control line Scan1[n+4] of the row changes from low level to high level to turn on the first switching transistor T1; the second scan control line Scan2[n+3] of the n+3th row changes from high level to The level becomes low level to close the third switch transistor T3; at this time, the data signal line inputs the data voltage V _DATA of the pixels in the nth row, that is, the voltage at point A changes from the reference level Vref to V _DATA , completing the The pixel data voltage of the nth row is loaded, and at this time, the voltage at point B is still maintained at 0V, and the corresponding voltage at point C is also maintained at Vref-V _TH .

(4) Idle state: the second scanning control line Scan2[n] in the nth row changes from low level to high level when the first scanning control line Scan1[n] in row n changes from high level to low level This stage continues until the second scan control line Scan2[n+3] in the n+3th row changes from low level to high level. In this stage, the voltage difference between point A and point C will remain constant, which is V _DATA −Vref+V _TH .

(5) Organic light-emitting diodes emit light: the first scanning control lines (Scan1[n], Scan1[n+1], Scan1[n+4]) of rows n, n+1 and n+4 are low level, The first, second, and fifth switching transistors (T1, T2, and T5) are turned off; the second scanning control lines (Scan2[n], Scan2[n+3]) of the nth and n+3 rows are high, and the third , The four switching transistors (T3, T4) are turned on; at this time, point B is in a floating point state, and its voltage will change with the voltage change at point C. At this time, the voltage at points A and C remains constant, which is V _DATA - Vref+V _TH , so the organic light-emitting diode emits the corresponding brightness, and the current flowing through the organic light-emitting diode is:

$\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; OLED</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; gs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; th</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; DATA</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}$

Among them, V _gs is the potential difference between the gate and source of the driving transistor T6, μ _n is the carrier mobility of the driving transistor T6, C _OX is the gate insulating layer capacitance of the driving transistor T6, and W/L is the driving transistor The aspect ratio of T6, V _DATA is the data voltage, V _th is the threshold voltage of the driving transistor T6, and VDD is the added power supply voltage. It can be seen from the above formula that the current flowing through the OLED has nothing to do with the threshold voltage V _th of the drive transistor T6 and the turn-on voltage of the OLED, so the pixel circuit can maintain The current flowing through the OLED is constant.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A pixel circuit of an active organic electroluminescent display, which is arranged at the part where the row-form scan lines that provide control signals and the column-form signal lines that provide data signals intersect each other, characterized in that it includes a first switch Transistor, second switch transistor, third switch transistor, fourth switch transistor, drive transistor, organic light emitting diode, first capacitor and second capacitor; The drain of the first switching transistor is connected to the data signal line, and the source of the first switching transistor is connected to the first plate of the first capacitor; The drain of the second switching transistor is connected to the first plate of the first capacitor, and the source of the second switching transistor is connected to a reference voltage; The drain of the third switching transistor is connected to the cathode of the organic light emitting diode, and the source of the third switching transistor is connected to the drain of the driving transistor; The drain of the fourth switching transistor is connected to the source of the driving transistor, and the source of the fourth switching transistor is grounded; The drain of the fifth switching transistor is connected to the second plate of the first capacitor, and the source of the fifth switching transistor is grounded; The drain of the driving transistor is connected to the source of the third switching transistor, the source of the driving transistor is connected to the drain of the fourth switching transistor, and the gate of the driving transistor is connected to the first plate of the first capacitor; The second capacitor is connected to the second plate of the first capacitor and the source of the drive transistor; The anode of the organic light emitting diode is connected to a power source. 2. The pixel circuit of an active organic electroluminescent display according to claim 1, further comprising first to fifth scanning signal control lines, the voltage of the gate of the first switching transistor is controlled by the first scanning signal The gate voltage of the second switching transistor is controlled by the second scanning signal line, the gate voltage of the third switching transistor is controlled by the third scanning signal line, and the gate voltage of the fourth switching transistor is controlled by the Controlled by the fourth scanning signal line, the voltage of the gate of the fifth switching transistor is controlled by the fifth scanning signal line. 3. The pixel circuit of an active organic electroluminescent display according to claim 2, wherein the gates of the first to fifth switching transistors of each row of pixel circuits are current signals output by the drive controller. Controlled by the line. 4. The pixel circuit of an active organic electroluminescent display according to claim 1, further comprising first to fourth scanning signal lines, the voltage of the gate of the first switching transistor is controlled by the first scanning signal line controlled, the voltage of the gate of the second switching transistor is controlled by the second scanning signal line, the voltage of the gate of the third switching transistor is controlled by the third scanning signal line, and the voltage of the gate of the fourth switching transistor is controlled by the first scanning signal line. Controlled by the four scanning signal lines, the voltage of the gate of the fifth switching transistor is controlled by the second scanning signal line. 5. The pixel circuit of an active organic electroluminescent display according to claim 4, wherein the gates of the first to fourth switching transistors of each row of the pixel circuit are signaled by a drive controller The current line is controlled; and the gate of the fifth switch transistor is controlled by the signal of the next line output by the second drive controller. 6. The pixel circuit of an active organic electroluminescence display according to claim 1, further comprising a first scanning signal line and a second scanning signal line, the voltage of the gate of the first switching transistor is controlled by the first Controlled by the scanning signal line, the gate voltage of the second switching transistor is also controlled by the first scanning signal line, the voltage of the gate of the third switching transistor is controlled by the second scanning signal line, and the gate voltage of the fourth switching transistor The voltage of the gate of the fifth switching transistor is also controlled by the second scanning signal line, and the voltage of the gate of the fifth switch transistor is controlled by the first scanning signal line. 7. The pixel circuit of an active organic electroluminescent display according to claim 6, wherein the gates of the second and fourth switching transistors of each row of pixel circuits are current signals output by the drive controller. The gate of the first transistor is controlled by the last 1+i rows of the signal output by the first scan driver, and the gate of the third transistor is controlled by the last i rows of the signal output by the second scan driver , the gate of the fifth transistor is controlled by the next line of the signal output by the first scan driver, wherein i is the ratio of the time of the threshold voltage latching phase to the time of the data loading phase. 8. The driving method of the pixel circuit of active organic electroluminescence display according to claim 3, is characterized in that, comprises the following steps: (1) Initialization: the first scanning control line and the fifth scanning control line of the pixels in the nth row are low, the first switching transistor and the fifth switching transistor are turned off; the second, third and fourth scanning control of the nth row of pixels line to a high level, the second, third, and fourth switching transistors are turned on accordingly; 1≤n≤M, M is the total number of scanning lines of the display; (2) Threshold voltage latching stage: the first scan control line of the pixels in the nth row keeps low level, and the first switch transistor remains closed; the second and third scan control lines of the pixels in the nth row keep high level, and the first switch transistor remains closed. 2. The third switching transistor remains on; the fourth scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the fourth switching transistor; the fifth scanning control line of the pixels in the nth row changes from a low level to Turning on the fifth switching transistor at a high level; completing latching the threshold voltage of the drive transistor, and the threshold voltage can be positive or negative; (3) Data loading: the first scan control line of the nth row of pixels changes from low level to high level to turn on the first switch transistor; the second and third scan control lines of the nth row of pixels change from high level to Turn off the second and third switching transistors at low level; the fourth scanning control line of pixels in the nth row remains low, and the fourth switching transistor remains closed; the fifth scanning control line of pixels in the nth row remains high, and the The fifth switching transistor remains on; at this time, the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row; (4) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor; the second scanning control line of the pixels in the nth row maintains a low level, and the second The switching transistor remains closed; the third and fourth scanning control lines of the nth row of pixels change from low level to high level to turn on the third and fourth switching transistors; the fifth scanning control line of the nth row of pixels changes from high level to high level Turning into a low level to turn off the fifth switching transistor; at this time, the organic light emitting diode emits a corresponding brightness according to the loaded data voltage. 9. The driving method of the pixel circuit of the active organic electroluminescent display according to claim 5, characterized in that, comprising the following steps: (1) Initialization: the first scan control line of the pixels in the nth row is low, and the first switching transistor is turned off; the second, third, and fourth scan control lines of the pixels in the nth row are high, and the second, third, and The four switching transistors are correspondingly turned on; at this time, the second scanning control line of the n+1th row is at a low level, and the fifth switching transistor is turned off; 1≤n≤M, M is the total number of scanning lines of the display screen; (2) Threshold voltage latching stage: the first scan control line of the pixels in the nth row keeps low level, and the first switch transistor remains closed; the second and third scan control lines of the pixels in the nth row keep high level, and the first switch transistor remains closed. The second and third switching transistors still remain on; the fourth scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the fourth switching transistor; at this time, the second scanning control line of the pixels in the n+1th row Turning on the fifth switching transistor from a low level to a high level; completing the threshold voltage latching of the driving transistor, and the threshold voltage can be positive or negative; (3) Data loading: the first scan control line of the nth row of pixels changes from low level to high level to turn on the first switch transistor; the second and third scan control lines of the nth row of pixels change from high level to Turn off the second and third switching transistors at low level; the fourth scanning control line of pixels in row n keeps low level, and the fourth switching transistor remains closed; the second scanning control line of pixels in row n+1 keeps high level , the fifth switch transistor remains turned on; at this time, the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row; (4) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row changes from a high level to a low level to turn off the first switching transistor; the second scanning control line of the pixels in the nth row maintains a low level, and the second The switching transistor remains closed; the third and fourth scanning control lines of the nth row of pixels change from low level to high level to turn on the third and fourth switching transistors; the second scanning control line of the n+1th row of pixels changes from high to high level becomes low level to turn off the fifth switching transistor; at this time, the organic light emitting diode emits corresponding brightness according to the loaded data voltage. 10. The driving method of the pixel circuit of the active organic electroluminescent display according to claim 7, characterized in that, comprising the following steps: (1) Initialization: the first scanning control line of the pixels in the nth row is given a high level, and the second switching transistor is turned on; the second scanning control line of the pixels in the nth row is given a high level, and the fourth switching transistor is turned on accordingly; At this time, the first scanning control line of the n+1th row and the n+1+ith row is low level, the first switching transistor and the fifth switching transistor are turned off; the second scanning control line of the n+ith row is low level, the third switch crystal is turned off; 1≤n≤M, M is the total number of scan lines of the display; (2) Threshold voltage latch stage: the first scan control line of the nth row of pixels maintains a high level, and the second switch transistor remains on; the second scan control line of the nth row of pixels changes from high level to low level, the fourth switching transistor is turned off; at this time, the first scanning control line of the n+1th row of pixels changes from low level to high level, and the fifth switching transistor is turned on; the n+1+ith row of pixels The first scanning control line still maintains a low level, and the first switching transistor is still turned off; the second scanning control line of the n+ith row of pixels still maintains a high level to turn on the third switching transistor; the threshold voltage lock of the driving transistor is completed stored, and the threshold voltage can be positive or negative; (3) Data loading: the first scanning control line of the pixels in the nth row changes from high level to low level, and the second switching transistor is turned off; the second scanning control line of the pixels in the nth row maintains a low level, and the fourth switch The transistor is still off; at this time, the first scanning control line of the pixels in the n+1th row maintains a high level, and the fifth switch transistor is still turned on; the first scanning control line of the pixels in the n+1+ith row is switched from a low level to becomes high level, the first switching transistor is turned on; the second scanning control line of the n+ith row of pixels changes from high level to low level, and the third switching transistor is turned off; the threshold voltage latch of the driving transistor is completed , and the threshold voltage can be positive or negative; the data signal line inputs the data voltage of the pixels in the nth row to complete the loading of the pixel data voltage in the nth row; (4) Idle state: the first scanning control line of the pixels in the nth row is kept low, and the second switching transistor is kept closed; the second scanning control line of the pixels in the nth row is kept low, and then becomes high level, the fourth switching transistor is kept off first, and then turned on; at this time, the first scanning control line of the n+1th row of pixels changes from high level to low level, and then maintains low level, and the fifth switching transistor is turned off ; The first scanning control line of the n+1+i row of pixels is maintained at a high level, and then becomes a low level, the first switching transistor is kept on and then turned off; the second scan of the n+i row of pixels The control line maintains a low level, and the third switch transistor remains turned off; (5) Organic light-emitting diodes emit light: the first scanning control line of the pixels in the nth row maintains a low level, and the second switching transistor remains closed; the second scanning control line of the pixels in the nth row maintains a high level, and the fourth switch The transistor remains turned on; at this time, the first scanning control line of the n+1th row of pixels maintains a low level, and the fifth switching transistor is turned off; the first scanning control line of the n+1+ith row of pixels maintains a low level, The first switching transistor remains off; the second scanning control line of the n+ith row of pixels changes from low level to high level, and the third switching transistor is turned on; at this time, the organic light emitting diode emits a corresponding signal according to the loaded data voltage. brightness.