CN101697269A - Pixel circuit and pixel driving method - Google Patents

Abstract

The invention discloses a pixel circuit, which includes an organic light emitting diode, a storage capacitor, a driving transistor and first to fourth switching transistors. The driving transistor is used to drive the organic light emitting diode to light up. Its first source/drain is electrically coupled to one end of the storage capacitor, its second source/drain is electrically coupled to the organic light emitting diode, and its gate is connected through the first switching transistor to receive the data voltage. The turn-on voltages of the gates of the first switch transistor and the second switch transistor are opposite to each other, and the on/off states of the two are determined by the same control signal. Similarly, the turn-on voltages of the gates of the third switch transistor and the fourth switch transistor are opposite to each other, and the on/off states of the two are determined by the same control signal. The present invention also provides a pixel driving method related to the above pixel circuit.

Description

Pixel circuit and pixel driving method

technical field

The present invention relates to the technical field of OLED display, and in particular to a pixel circuit and a pixel driving method.

Background technique

The pixels of an active matrix OLED (Organic Light Emitting Diode, OLED) display generally use transistors and storage capacitors to store charges to control the brightness of the OLED. Please refer to FIG. 1 , which is a schematic diagram of a conventional pixel circuit. The pixel circuit 10 is a two-transistor-one-capacitor (2T1C) structure, which includes a P-type driving transistor M1 , a P-type switching transistor Ms, a storage capacitor Cst, and an organic light emitting diode 16 . Both ends of the storage capacitor Cst are connected between the gate and the source of the driving transistor M1; the source of the driving transistor M1 is electrically coupled to the power supply voltage VDD, and the drain of the driving transistor M1 is electrically coupled to the organic light emitting diode. The anode of the organic light emitting diode 16 is electrically coupled to another power supply voltage VSS, and the gate of the driving transistor M1 is electrically coupled to the data line DL through the switching transistor Ms to receive the data voltage Vdata from the data line DL; the switch The gate of the transistor Ms is electrically coupled to the scan line Scan, so that its on/off state is controlled by the scan line Scan. Here, the brightness performance of the OLED 16 can be controlled by providing different data voltages Vdata.

However, for each pixel circuit of an active matrix organic light emitting diode display, due to factors such as process-related transistor threshold voltage shift (Shift), organic light emitting diode material attenuation and/or operating time, etc. During the working process of the light-emitting diode display, the pixel current of the pixel circuit must be effectively compensated by adjusting the data voltage Vdata in order to obtain a better brightness performance and thus a better display effect. Therefore, in order to achieve the purpose of effectively compensating the pixel current of the pixel circuit, it is necessary to rationally design the structural configuration of the pixel circuit and the driving method of the pixel circuit, otherwise, abnormal display or compensation effect failure may easily occur during the working process of the display.

Contents of the invention

The purpose of the present invention is to provide a pixel circuit to suppress the occurrence of abnormal display or failure of compensation effect.

Another object of the present invention is to provide a pixel driving method to prevent the occurrence of abnormal display or failure of compensation effect.

A pixel circuit provided by an embodiment of the present invention includes an organic light emitting diode, a storage capacitor, a driving transistor, a first switching transistor, a second switching transistor, a third switching transistor and a fourth switching transistor. The driving transistor is used to drive the organic light emitting diode to light up. Its first source/drain is electrically coupled to the first end of the storage capacitor, and its second source/drain is electrically coupled to the organic light emitting diode. The gate of the first switching transistor receives the first scanning signal due to the electrical coupling relationship, the first source/drain thereof is electrically coupled to the gate of the driving transistor, and the second source/drain thereof is electrically coupled to the gate of the driving transistor. relationship to receive the data voltage. The gate of the second switching transistor receives the first scanning signal due to the electrical coupling relationship, its first source/drain is electrically coupled to the first preset voltage, and its second source/drain is electrically coupled to The first terminal of the storage capacitor. The gate of the third switching transistor receives the second scanning signal due to the electrical coupling relationship, its first source/drain is electrically coupled to the second preset voltage, and its second source/drain is electrically coupled to The second terminal of the storage capacitor. The gate of the fourth switching transistor receives the second scanning signal due to the electrical coupling relationship, its first source/drain is electrically coupled to the gate of the driving transistor, and its second source/drain is electrically coupled to The second terminal of the storage capacitor. Wherein, the gate on voltages (Gate On Voltage) of the first switch transistor and the second switch transistor are opposite to each other, and the gate on voltages of the third switch transistor and the fourth switch transistor are opposite to each other.

In an embodiment of the present invention, the above-mentioned first switch transistor is an N-type transistor, and the second switch transistor is a P-type transistor; further, the third switch transistor is a P-type transistor, and the fourth switch transistor is an N-type transistor.

A pixel driving method proposed by yet another embodiment of the present invention is suitable for implementation in an active matrix organic light emitting diode display. Wherein, the active matrix organic light emitting diode display includes a data line and a first pixel and a second pixel electrically coupled to the data line. Each of the first pixel and the second pixel includes an organic light emitting diode, a storage capacitor, a driving transistor, and a first switching transistor; the driving transistor is used to drive the organic light emitting diode to light up, and the first source/drain electrode of the driving transistor is electrically coupled to the first terminal of the storage capacitor, the second source/drain of the driving transistor is electrically coupled to the organic light emitting diode, the gate of the driving transistor is electrically coupled to the first source/drain of the first switching transistor, The second source/drain of the first switch transistor is electrically coupled to the data line. Moreover, the pixel driving method is used to sequentially drive the first pixel and the second pixel, and the process of driving each pixel in the first pixel and the second pixel includes the steps: (a) in the reset phase, providing the second pixel A preset voltage is supplied to the first terminal of the storage capacitor, and a second preset voltage is provided to the second terminal of the storage capacitor; (b) in the writing phase, the first switch transistor is turned on so that the data voltage on the data line passes through the second terminal a switching transistor is transmitted to the gate of the driving transistor, and the first end of the storage capacitor is discharged through the driving transistor and the organic light emitting diode, and the second end of the storage capacitor is maintained at a second preset voltage; and (c) in the light emitting stage , and then provide the first preset voltage to the first end of the storage capacitor, so that the first switching transistor is in the cut-off state, and the second end of the storage capacitor is connected to the gate of the driving transistor, so that the driving transistor drives the organic light emitting diode to emit light. Bright. Wherein, the data voltage on the data line transiently occurs from the moment when the first switching transistor of the first pixel is turned off after the writing phase to before the first switching transistor of the second pixel is turned on during the writing phase ( Transient).

In an embodiment of the present invention, when each of the first pixel and the second pixel further includes a second switch transistor and a third switch transistor, and the second switch transistor is electrically coupled between the first preset voltage and the second switch transistor. Between the first terminals of the storage capacitor, and the third switching transistor is electrically coupled between the second preset voltage and the second terminal of the storage capacitor; the aforementioned first preset voltage is provided to the storage capacitor during the reset phase The step of providing the second predetermined voltage to the second end of the storage capacitor includes: making the first switch transistor in an off state, and turning on the second switch transistor and the third switch transistor. Further, the on/off states of the first switch transistor and the second switch transistor are determined by the same control signal.

In an embodiment of the present invention, when each of the first pixel and the second pixel further includes a fourth switching transistor, and the fourth switching transistor is electrically coupled to the second end of the storage capacitor and the gate of the driving transistor When between poles; in the aforementioned writing stage, the first switching transistor is turned on so that the data voltage on the data line is transmitted to the gate of the driving transistor through the first switching transistor, and the first end of the storage capacitor is passed through the driving transistor and the organic The step of discharging the light-emitting diode and maintaining the second terminal of the storage capacitor at the second preset voltage includes: turning on the first switching transistor, turning off the second switching transistor, making the third switching transistor in a conducting state and making the fourth switching transistor is closed. Further, the on/off of the third switch transistor and the fourth switch transistor are determined by the same control signal.

In an embodiment of the present invention, in the light-emitting phase, the first preset voltage is provided to the first end of the storage capacitor, so that the first switching transistor is in an off state, and the second end of the storage capacitor is connected to the drive transistor. The step of connecting the gates so that the drive transistor drives the organic light emitting diode to light includes: turning off the first switch transistor, turning on the second switch transistor, turning off the third switch transistor and turning on the fourth switch transistor.

In an embodiment of the present invention, when the active matrix organic light emitting diode display further includes a demultiplexer and the data line is electrically coupled to the output terminal of the demultiplexer, before the writing phase, the The method includes the step of: enabling the demultiplexer, so that the data voltage is provided to the data line through the demultiplexer.

Another pixel driving method proposed by another embodiment of the present invention is suitable for implementation in an active matrix organic light emitting diode display. Wherein, the active matrix organic light emitting diode display includes a data line and a first pixel and a second pixel electrically coupled to the data line. Each of the first pixel and the second pixel includes an organic light emitting diode, a storage capacitor, a driving transistor, and a first switching transistor; the driving transistor is used to drive the organic light emitting diode to light up, and the first source/drain electrode of the driving transistor is electrically coupled to the first terminal of the storage capacitor, the second source/drain of the driving transistor is electrically coupled to the organic light emitting diode, the gate of the driving transistor is electrically coupled to the first source/drain of the first switching transistor, The second source/drain of the first switch transistor is electrically coupled to the data line. The pixel driving method is used to sequentially drive the first pixel and the second pixel, and includes steps in the process of driving each pixel in the first pixel and the second pixel: (1) in the reset phase, providing a first preset voltage to the first end of the storage capacitor, and provide a second preset voltage to the second end of the storage capacitor; (II) in the writing phase, make the data line provide the data voltage to the gate of the drive transistor through the first switch transistor , and discharge the first terminal of the storage capacitor through the driving transistor and the organic light emitting diode, and maintain the second terminal of the storage capacitor at the second preset voltage; and (III) provide the first preset voltage to the storage during the light-emitting phase The first end of the capacitor makes the first switching transistor in the cut-off state, and makes the second end of the storage capacitor communicate with the gate of the driving transistor, so that the driving transistor drives the organic light emitting diode to light up. Wherein, the process of driving the second pixel further includes a step: in the writing stage, before the data line supplies the data voltage to the gate of the drive transistor through the first switch transistor, the data line supplies the precharge voltage to the gate of the drive transistor through the first switch transistor. Provided to the gate of the drive transistor; the precharge voltage is switched from the moment when the first switching transistor of the first pixel is turned off after the writing phase to before the first switching transistor of the second pixel is turned on during the writing phase provided to the data line; and the precharge voltage is greater than the sum of the data voltage provided to the gate of the driving transistor of the second pixel and the threshold voltage of the driving transistor of the second pixel.

In an embodiment of the present invention, when each of the first pixel and the second pixel further includes a second switch transistor and a third switch transistor, and the second switch transistor is electrically coupled between the first preset voltage and the second switch transistor. Between the first terminals of the storage capacitor, and the third switching transistor is electrically coupled between the second preset voltage and the second terminal of the storage capacitor; the aforementioned first preset voltage is provided to the storage capacitor during the reset phase The step of providing the second predetermined voltage to the second end of the storage capacitor includes: turning off the first switch transistor, and turning on the second switch transistor and the third switch transistor. Further, the on/off states of the first switch transistor and the second switch transistor are determined by the same control signal.

In an embodiment of the present invention, when each of the first pixel and the second pixel further includes a fourth switching transistor, and the fourth switching transistor is electrically coupled to the second end of the storage capacitor and the gate of the driving transistor When between poles; in the aforementioned writing phase, the data line is provided to the gate of the drive transistor through the first switch transistor to provide the data voltage to the gate of the drive transistor, and the first end of the storage capacitor is discharged through the drive transistor and the organic light emitting diode, and the storage is maintained. The step of setting the second terminal of the capacitor at the second preset voltage includes: turning on the first switch transistor, turning off the second switch transistor, making the third switch transistor in an on state and making the fourth switch transistor in an off state. Further, the on/off states of the third switch transistor and the fourth switch transistor are determined by the same control signal.

In an embodiment of the present invention, in the light-emitting phase, the first preset voltage is provided to the first end of the storage capacitor, so that the first switching transistor is in an off state, and the second end of the storage capacitor is connected to the drive transistor. The step of connecting the gates so that the drive transistor drives the organic light emitting diode to light includes: turning off the first switch transistor, turning on the second switch transistor, turning off the third switch transistor and turning on the fourth switch transistor.

In an embodiment of the present invention, when the active matrix organic light emitting diode display further includes a demultiplexer and the data line is electrically coupled to the output end of the demultiplexer, during the process of driving the second pixel, further The method comprises the steps of: enabling the demultiplexer to provide a precharge voltage to the data line through the demultiplexer; and enabling the demultiplexer again to provide the precharge voltage of the data line through the demultiplexer voltage changes to the data voltage.

In the embodiment of the present invention, the pixel circuit structure and the pixel driving method are specifically designed so that: in the reset phase of the pixel driving method, the data voltage on the data line will not be coupled to the gate of the driving transistor, and in the writing phase The potential of the end of the storage capacitor electrically coupled with the drive transistor can be normally discharged to the required potential; so that the pixel current of the pixel circuit can be effectively compensated, and there will be no problems of display abnormality or compensation effect failure.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of a conventional pixel circuit;

FIG. 2 shows a partial structural block diagram of an active matrix organic light emitting diode display related to the first embodiment of the present invention;

3 depicts a timing diagram of scanning signals and data voltages related to the pixel driving method of the first embodiment of the present invention;

FIG. 4 shows a partial structural block diagram of an active matrix organic light emitting diode display related to the second embodiment of the present invention;

FIG. 5 is a timing diagram of scanning signals and demultiplexer control signals related to the pixel driving method according to the second embodiment of the present invention.

Among them, reference signs

10: Pixel circuit 20, 40: Active matrix organic light emitting diode display

22, 42: Data drive circuit 1～Z: Output terminal of data drive circuit

43: Pre-charging circuit Vdata: data voltage

PC_H: Precharge 24, 44: Multiplexer

DL, DLi～DLk: data lines

Scan, Scan(N-1), Scan(N), EM(N-1), EM(N): scan line

Rn-1, Rn: pixel row i～k: pixel column

VDD, VSS: power supply voltage P(n-1)i～P(n-1)k and Pni～Pnk: pixel circuit

Vref: reference voltage GND: ground voltage

M1: Driving transistor Ms, M2～M5: Switching transistor

Cst: storage capacitor A, B: storage capacitor terminals

26, 46: OLED S1, S1′: reset phase

S2, S2': Writing stage S3, S3': Lighting stage

DMUX: Demultiplexer control signal

Scan(N-1), Scan(N), EM(N-1), EM(N): scan signal

t1, t2: time

Detailed ways

Referring to FIG. 2 and FIG. 3, FIG. 2 shows a partial structural block diagram of an active matrix OLED display related to the first embodiment of the present invention, and FIG. 3 shows a pixel related to the first embodiment of the present invention Timing diagram of scan signal and data voltage of the driving method.

As shown in FIG. 2 , the active matrix OLED display 20 includes a data drive circuit 22, a demultiplexer 24, data lines DLi˜DLk, scan lines Scan(N-1) and Scan(N), and a scan line EM. (N-1) and EM(N), and a plurality of pixel circuits P(n-1)i～P(n-1)k and Pni～Pnk; each pixel circuit P(n-1)i～P(n -1) k and Pni˜Pnk are electrically coupled to respective scan lines Scan(N-1) and Scan(N), scan lines EM(N-1) and EM(N) and data lines DLi˜DLk, respectively, And arranged in the Rn-1th and Rnth pixel rows and Ci-Ckth pixel columns in a matrix. The data driving circuit 22 is used to provide the data voltage Vdata, and has a plurality of output terminals 1Z. Each of the data lines DLi˜DLk is electrically coupled to one of the plurality of output terminals 1˜Z of the data driving circuit 22 through the demultiplexer 24 to receive the data voltage Vdata. It should be noted here that the active matrix organic light emitting diode 20 of this embodiment may not be provided with the demultiplexer 24, and correspondingly, each data line DLi˜DLk is respectively directly coupled to a plurality of outputs of the data driving circuit 22. Correspondence in terminal 1~Z.

Based on the above, each pixel circuit P(n-1)i~P(n-1)k and Pni~Pnk has a 5T1C structure and includes: an organic light emitting diode 26, a storage capacitor Cst, a P-type driving transistor M1, an N-type switch Transistors M2 and M5 and P-type switching transistors M3 and M4. Wherein, the driving transistor M1 is used to drive the OLED 26 to light up, the source of the driving transistor M1 is electrically coupled to the terminal A of the storage capacitor Cst, and the drain of the driving transistor M1 is electrically coupled to the anode of the OLED 26 , the cathode of the organic light emitting diode 26 is electrically coupled to the power supply voltage VSS. The source of the switching transistor M2 is electrically coupled to the gate of the driving transistor M1, the drain of the switching transistor M2 is electrically coupled to one of the data lines DLi˜DLk, and the gate of the switching transistor M2 is electrically coupled to the scanning Line EM(N-1) (or EM(N)) to receive the scan signal EM(N-1) (or EM(N)). The source of the switch transistor M3 is electrically coupled to the power supply voltage VDD, the drain of the switch transistor M3 is electrically coupled to the A terminal of the storage capacitor Cst, and the gate of the switch transistor M3 is electrically coupled to the scanning line EM (N- 1) (or EM(N)) to receive the scan signal EM(N-1) (or EM(N)). The source of the switching transistor M4 is electrically coupled to the reference voltage Vref, the drain of the switching transistor M4 is electrically coupled to the terminal B of the storage capacitor Cst, and the gate of the switching transistor M4 is electrically coupled to the scan line Scan (N− 1) (or Scan(N)) to receive the scan signal Scan(N−1) (or Scan(N)). The source of the switching transistor M5 is electrically coupled to the gate of the driving transistor M1, the drain of the switching transistor M5 is electrically coupled to the terminal B of the storage capacitor Cst, and the gate of the switching transistor M5 is electrically coupled to the scan line Scan. (N-1) (or Scan(N)) to receive the scan signal Scan(N-1) (or Scan(N)). It can also be seen from FIG. 2 and FIG. 3 that the gates of the switching transistors M2 and M3 are electrically coupled to each other, the gate turn-on voltages are opposite to each other, and the on/off states of the switching transistors M2 and M3 are controlled by the same signal EM(N-1) or EM(N); similarly, the gates of the switch transistors M4 and M5 are electrically coupled to each other, the gate turn-on voltages are opposite to each other, and the conduction/conduction of the switch transistors M4 and M5 The cut-off state is determined by the same control signal Scan(N-1) or Scan(N).

The pixel driving method of the active matrix organic light emitting diode display 20 will be described in detail below in conjunction with FIG. 2 and FIG. for example. It can be seen from FIG. 3 that the process of driving the pixel circuit P(n-1)i includes a reset phase S1', a writing phase S2' and a light emitting phase S3'. Similarly, in the process of driving the pixel circuit Pni Including reset phase S1, writing phase S2 and light emitting phase S3.

Specifically, in the reset phase S1 (S1'), Scan(N) (Scan(N-1)) and EM(N) (EM(N-1)) are both low voltage potentials; at this time, the switching transistor M3 and M4 are in the on state and the switching transistors M2 and M5 are in the off state, the power supply voltage VDD and the reference voltage Vref are provided to the A terminal and the B terminal of the storage capacitor Cst through the switching transistors M3 and M4 respectively, since the switching transistor M2 is in the off state, The data voltage Vdata on the data line DLi is not coupled to the gate of the driving transistor M1.

In the writing phase S2 (S2'), Scan(N) (Scan(N-1)) is a low voltage potential and EM(N) (EM(N-1)) is a high voltage potential; at this time, the switching transistor M2 and M4 are in the on state and the switching transistors M3 and M5 are in the off state, the data voltage Vdata provided to the data line DLi is transmitted to the gate of the driving transistor M1 because the switching transistor M2 is on, and the potential of the A terminal of the storage capacitor Cst is changed from VDD is discharged to Vdata+Vth1 through the driving transistor M1 and the OLED 26 , and the potential of the terminal B of the storage capacitor Cst is maintained at Vref because the switching transistor M4 is turned on. Wherein Vth1 is the critical voltage of the driving transistor M1, the data voltage Vdata required by the pixel circuits P(n-1)i and Pni is obtained by enabling the demultiplexer 24 before the respective writing phases S2 and S2′ respectively. Provided to the data line DLi.

In the light-emitting phase S3 (S3'), Scan (N) (Scan (N-1)) is a high voltage potential and EM (N) (EM (N-1)) is a low voltage potential; at this time, the switching transistor M3 and M5 is in the on state and the switching transistors M2 and M4 are in the off state, the power supply voltage VDD is provided to the A terminal of the storage capacitor Cst through the switching transistor M3 again, and the B terminal of the storage capacitor Cst is connected to the driving transistor M1 due to the switching transistor M5 being on. The gate is connected, so that the driving transistor M1 generates a pixel current according to the charge stored in the storage capacitor Cst to drive the OLED 26 to light up.

Further, it can be seen from FIG. 3 that the data voltage Vdata on the data line DLi is transferred from the pixel circuit P(n-1)i to the pixel circuit at the time t1 when the switching transistor M2 of the pixel circuit P(n-1)i is turned off after the writing phase S2′. The switch transistor M2 of Pni undergoes a transient (Transient), such as jumping from a low voltage level to a high voltage level, between the time t2 before the writing phase S2 is turned on.

Here, since the data voltage Vdata has been changed to Vdata(n) (corresponding to the data voltage written into the pixel circuit Pni) before the writing phase S2 of the pixel circuit Pni, the terminal A of the storage capacitor Cst (that is, the drive transistor M1 The potential of the source electrode) can normally change from VDD to Vdata(n)+Vth1, so that the problems of display abnormality or compensation effect failure in the prior art can be effectively solved.

Referring to FIG. 4 and FIG. 5, FIG. 4 shows a partial structural block diagram of an active matrix OLED display related to the second embodiment of the present invention, and FIG. 5 shows a pixel related to the second embodiment of the present invention Timing diagram of scanning signals and demultiplexer control signals of the driving method.

As shown in FIG. 4 , the active matrix organic light emitting diode display 40 includes a data driving circuit 42, a pre-charging circuit 43, a demultiplexer 44, data lines DLi˜DLk, scan lines Scan(N-1) and Scan(N-1). ), scanning lines EM(N-1) and EM(N), and a plurality of pixel circuits P(n-1)i~P(n-1)k and Pni~Pnk; each pixel circuit P(n-1) i～P(n-1)k and Pni～Pnk are electrically coupled to respective scan lines Scan(N-1) and Scan(N), scan lines EM(N-1) and EM(N) and data The lines DLi˜DLk are arranged in a matrix in the Rn−1 and Rn pixel rows and Ci˜Ck pixel columns. The data driving circuit 42 is used for providing the data voltage Vdata, which has a plurality of output terminals 1Z; the pre-charging circuit 43 is used for providing the pre-charging voltage PC_H. Each data line DLi˜DLk is electrically coupled to one of the plurality of output terminals 1˜Z of the data driving circuit 12 and the precharge circuit 43 through the demultiplexer 14 to selectively receive the data voltage Vdata and the precharge voltage PC_H .

Based on the above, each pixel circuit P(n-1)i~P(n-1)k and Pni~Pnk has a 5T1C structure and includes: an organic light emitting diode 46, a storage capacitor Cst, a P-type driving transistor M1, an N-type switch Transistors M2 and M5 and P-type switching transistors M3 and M4. Wherein, the driving transistor M1 is used to drive the organic light emitting diode 46, the source of the driving transistor M1 is electrically coupled to the terminal A of the storage capacitor Cst, and the drain of the driving transistor M1 is electrically coupled to the anode of the organic light emitting diode 46. The cathode of the LED 46 is electrically coupled to the power supply voltage VSS. The source of the switching transistor M2 is electrically coupled to the gate of the driving transistor M1, the drain of the switching transistor M2 is electrically coupled to one of the data lines DLi˜DLk, and the gate of the switching transistor M2 is electrically coupled to the scanning Line EM(N-1) (or EM(N)) to receive the scan signal EM(N-1) (or EM(N)). The source of the switch transistor M3 is electrically coupled to the power supply voltage VDD, the drain of the switch transistor M3 is electrically coupled to the A terminal of the storage capacitor Cst, and the gate of the switch transistor M3 is electrically coupled to the scanning line EM (N- 1) (or EM(N)) to receive the scan signal EM(N-1) (or EM(N)). The source of the switching transistor M4 is electrically coupled to the reference voltage Vref, the drain of the switching transistor M4 is electrically coupled to the terminal B of the storage capacitor Cst, and the gate of the switching transistor M4 is electrically coupled to the scan line Scan (N− 1) (or Scan(N)) to receive the scan signal Scan(N−1) (or Scan(N)). The source of the switching transistor M5 is electrically coupled to the gate of the driving transistor M1, the drain of the switching transistor M5 is electrically coupled to the terminal B of the storage capacitor Cst, and the gate of the switching transistor M5 is electrically coupled to the scan line Scan. (N-1) (or Scan(N)) to receive the scan signal Scan(N-1) (or Scan(N)). It can also be seen from FIG. 4 and FIG. 5 that the gates of the switching transistors M2 and M3 are electrically coupled to each other, the gate turn-on voltages are opposite to each other, and the on/off states of the switching transistors M2 and M3 are controlled by the same signal EM(N-1) or EM(N); similarly, the gates of the switch transistors M4 and M5 are electrically coupled to each other, the gate turn-on voltages are opposite to each other, and the conduction/conduction of the switch transistors M4 and M5 The cut-off state is determined by the same control signal Scan(N-1) or Scan(N).

The pixel driving method of the active matrix organic light emitting diode display 40 will be described in detail below in conjunction with FIG. 4 and FIG. for example. It can be seen from FIG. 5 that the process of driving the pixel circuit P(n-1)i includes a reset phase S1', a writing phase S2' and a light emitting phase S3'. Similarly, in the process of driving the pixel circuit Pni Including reset phase S1, writing phase S2 and light emitting phase S3.

Specifically, in the reset phase S1 (S1'), Scan(N) (Scan(N-1)) and EM(N) (EM(N-1)) are both low voltage potentials; at this time, the switching transistor M3 and M4 are in the on state and the switching transistors M2 and M5 are in the off state, the power supply voltage VDD and the reference voltage Vref are provided to the A terminal and the B terminal of the storage capacitor Cst through the switching transistors M3 and M4 respectively, since the switching transistor M2 is in the off state, The data voltage Vdata on the data line DLi is not coupled to the gate of the driving transistor M1.

In the writing phase S2 (S2'), Scan(N) (Scan(N-1)) is a low voltage potential and EM(N) (EM(N-1)) is a high voltage potential; at this time, the switching transistor M2 and M4 are in the on state and the switching transistors M3 and M5 are in the off state, the data line DLi first provides the precharge voltage PC H to the gate of the driving transistor M1 through the switching transistor M2, and the potential of the A terminal of the storage capacitor Cst is passed from VDD through the driving transistor M1 and the organic light emitting diode 46 are discharged to PC_H+Vth1; after that, when the precharge voltage PC_H on the data line DLi is changed to the data voltage Vdata, the data line DLi provides the data voltage Vdata to the gate of the driving transistor M1 through the switching transistor M2 , and the potential of the terminal A of the storage capacitor Cst continues to discharge from PC_H+Vth1 to Vdata+Vth1 through the driving transistor M1 and the organic light emitting diode 46; the potential of the terminal B of the storage capacitor Cst remains at Vref because the switching transistor M4 is in the on state. Where Vth1 is the critical voltage of the driving transistor M1, the precharge voltage PC_H and the data voltage Vdata required by the pixel circuits P(n-1)i and Pni are sequentially provided to the data by enabling the demultiplexer 44 twice. On the line DLi.

Wherein, in the process of driving the pixel circuit Pni, the precharge voltage PC_H is transferred from the switching transistor M2 of the pixel circuit P(n-1)i to the switching transistor M2 of the pixel circuit Pni at the time t1 when the switching transistor M2 of the pixel circuit P(n-1)i is turned off after the writing phase S2′ During the time t2 before the writing phase S2 is turned on, it is supplied to the data line DLi; and the magnitude of the precharge voltage PC_H is greater than the data voltage Vdata(n) supplied to the gate of the driving transistor M1 of the pixel circuit Pni and the sum of the threshold voltage Vth1 of the driving transistor M1 of the pixel circuit Pni. Here, due to the provision of the precharge voltage PC_H, the potential of the terminal A of the storage capacitor Cst (that is, the source of the driving transistor M1) can normally change from VDD to Vdata(n)+Vth1, so that the existing The problem of abnormal display or failure of compensation effect existing in the technology can be effectively solved.

In the light-emitting phase S3 (S3'), Scan (N) (Scan (N-1)) is a high voltage potential and EM (N) (EM (N-1)) is a low voltage potential; at this time, the switching transistor M3 and M5 is in the on state and the switching transistors M2 and M4 are in the off state, the power supply voltage VDD is provided to the A terminal of the storage capacitor Cst through the switching transistor M3 again, and the B terminal of the storage capacitor Cst is connected to the driving transistor M1 due to the switching transistor M5 being on. The gate is connected, so that the driving transistor M1 generates a pixel current according to the charge stored in the storage capacitor Cst to drive the organic light emitting diode 46 to light up.

In summary, the embodiments of the present invention specifically design the pixel circuit structure and the pixel driving method, so that: in the reset phase of the pixel driving method, the data voltage on the data line will not be coupled to the gate of the driving transistor, and In the writing phase, the potential of the end of the storage capacitor electrically coupled to the driving transistor can be normally discharged to the required potential; so that the pixel current of the pixel circuit can be effectively compensated, and there will be no abnormal display or compensation effect failure The problem.

In addition, those skilled in the art can make appropriate changes to the pixel circuit, the pixel driving method and the structure of the active matrix organic light emitting diode display to which it is applied, such as appropriately changing the number of transistors in the pixel circuit, the active The number of pixels of the matrix organic light emitting diode display, the type of each transistor (P-type or N-type), the electrical connection relationship between the source and drain of each transistor is interchanged, and so on.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (17)

1. an image element circuit is characterized in that, comprising:

One Organic Light Emitting Diode;

One storage capacitors;

One driving transistors, shinny in order to drive this Organic Light Emitting Diode, first source/drain electrode of this driving transistors is electrically coupled to one first end of this storage capacitors, and second source/drain electrode of this driving transistors is electrically coupled to this Organic Light Emitting Diode;

One first switching transistor, the grid of this first switching transistor receives one first sweep signal because of the electric property coupling relation, first source/drain electrode of this first switching transistor is electrically coupled to the grid of this driving transistors, and second source/drain electrode of this first switching transistor receives a data voltage because of the electric property coupling relation;

One second switch transistor, the transistorized grid of this second switch receives this first sweep signal because of the electric property coupling relation, the transistorized first source/drain electrode of this second switch is electrically coupled to one first predeterminated voltage, and the transistorized second source/drain electrode of this second switch is electrically coupled to this first end of this storage capacitors;

One the 3rd switching transistor, the grid of the 3rd switching transistor receives one second sweep signal because of the electric property coupling relation, first source/drain electrode of the 3rd switching transistor is electrically coupled to one second predeterminated voltage, and second source/drain electrode of the 3rd switching transistor is electrically coupled to one second end of this storage capacitors; And

One the 4th switching transistor, the grid of the 4th switching transistor receives this second sweep signal because of the electric property coupling relation, first source/drain electrode of the 4th switching transistor is electrically coupled to this grid of this driving transistors, and the 4th transistorized second source/drain electrode is electrically coupled to this second end of this storage capacitors;

Wherein, the transistorized grid cut-in voltage of this first switching transistor and this second switch is anti-phase each other, and the grid cut-in voltage of the 3rd switching transistor and the 4th switching transistor is anti-phase each other.

2. image element circuit according to claim 1 is characterized in that, this first switching transistor is the N transistor npn npn, and the second switch transistor is the P transistor npn npn.

3. image element circuit according to claim 2 is characterized in that, the 3rd switching transistor is the P transistor npn npn, and the 4th switching transistor is the N transistor npn npn.

4. image element driving method, be suitable for being executed in an active matrix organic LED display, it is characterized in that, one first pixel and second pixel that this active matrix organic LED display comprises a data line and is electrically coupled to this data line, each pixel in this first pixel and this second pixel comprises an Organic Light Emitting Diode, one storage capacitors, one driving transistors and one first switching transistor, this driving transistors is shinny in order to drive this Organic Light Emitting Diode, first source/drain electrode of this driving transistors is electrically coupled to one first end of this storage capacitors, second source/drain electrode of this driving transistors is electrically coupled to this Organic Light Emitting Diode, the grid of this driving transistors is electrically coupled to first source/drain electrode of this first switching transistor, and second source/drain electrode of this first switching transistor is electrically coupled to this data line; This driving method is in order to driving this first pixel and this second pixel in regular turn, and comprises step in the process of each pixel in driving this first pixel and this second pixel:

In a reset phase, one first predeterminated voltage this first end to this storage capacitors is provided, and one second end of one second predeterminated voltage to this storage capacitors is provided;

In a write phase, this first switching transistor of conducting makes the data voltage on this data line be sent to this grid of this driving transistors by this first switching transistor, and this first end that makes this storage capacitors is by this driving transistors and the discharge of this Organic Light Emitting Diode, and this second end of keeping storage capacitors is at this second predeterminated voltage; And

In a glow phase, this first predeterminated voltage this first end to this storage capacitors is provided again, make this first switching transistor be in cut-off state, and this second end of this storage capacitors is communicated with this grid of this driving transistors, to such an extent as to that this driving transistors drives this Organic Light Emitting Diode is shinny;

Wherein, this data voltage on this data line, moment that this first switching transistor from this first pixel is cut off after this write phase to this first switching transistor of this second pixel before this write phase is switched on, transition takes place.

5. image element driving method according to claim 4, it is characterized in that, each pixel in this first pixel and this second pixel also comprises a second switch transistor and one the 3rd switching transistor, this second switch transistor is electrically coupled between this first end of this first predeterminated voltage and this storage capacitors, and when the 3rd switching transistor is electrically coupled between this second end of this second predeterminated voltage and this storage capacitors, aforementioned in this reset phase, this first predeterminated voltage this first end to this storage capacitors is provided, and provides this second predeterminated voltage to the step of this second end of this storage capacitors to comprise:

Make this first switching transistor be in cut-off state, and this second switch transistor AND gate the 3rd switching transistor of conducting.

6. image element driving method according to claim 5 is characterized in that, the transistorized conduction and cut-off state of this first switching transistor and this second switch is determined by same control signal.

7. image element driving method according to claim 5, it is characterized in that, each pixel in this first pixel and this second pixel further comprises one the 4th switching transistor, and when the 4th switching transistor is electrically coupled between this grid of this second end of this storage capacitors and this driving transistors, aforementioned in this write phase, this first switching transistor of conducting makes this data voltage on this data line be sent to this grid of this driving transistors by this first switching transistor, and this first end that makes this storage capacitors is by this driving transistors and the discharge of this Organic Light Emitting Diode, and this second end of keeping storage capacitors comprises in the step of this second predeterminated voltage:

This first switching transistor of conducting by this second switch transistor, makes the 3rd switching transistor be in conducting state and makes the 4th switching transistor be in cut-off state.

8. image element driving method according to claim 7 is characterized in that, the conduction and cut-off state of the 3rd switching transistor and the 4th switching transistor is determined by same control signal.

9. image element driving method according to claim 7, it is characterized in that, aforementioned in this glow phase, this first predeterminated voltage this first end to this storage capacitors is provided again, make this first switching transistor be in cut-off state, and this second end of this storage capacitors is communicated with this grid of this driving transistors, to such an extent as to driving the shinny step of this Organic Light Emitting Diode, this driving transistors comprises:

By this first switching transistor, this second switch transistor of conducting, by the 3rd switching transistor and conducting the 4th switching transistor.

10. image element driving method according to claim 4, it is characterized in that, when this active matrix organic LED display comprises that also a demultiplexer and this data line are electrically coupled to an output terminal of this demultiplexer, before this write phase, also comprise step:

This demultiplexer of activation is to such an extent as to provide this data voltage to this data line by this demultiplexer.

11. image element driving method, be suitable for being executed in an active matrix organic LED display, it is characterized in that, one first pixel and second pixel that this active matrix organic LED display comprises a data line and is electrically coupled to this data line, each pixel in this first pixel and this second pixel comprises an Organic Light Emitting Diode, one storage capacitors, one driving transistors and one first switching transistor, this driving transistors is shinny in order to drive this Organic Light Emitting Diode, first source/drain electrode of this driving transistors is electrically coupled to one first end of this storage capacitors, second source/drain electrode of this driving transistors is electrically coupled to this Organic Light Emitting Diode, the grid of this driving transistors is electrically coupled to first source/drain electrode of this first switching transistor, and second source/drain electrode of this first switching transistor is electrically coupled to this data line; This driving method is in order to driving this first pixel and this second pixel in regular turn, and comprises step in the process of each pixel in driving this first pixel and this second pixel:

In a reset phase, one first predeterminated voltage this first end to this storage capacitors is provided, and one second end of one second predeterminated voltage to this storage capacitors is provided;

In a write phase, make this data line provide this grid with a data voltage to this driving transistors by this first switching transistor, and this first end that makes this storage capacitors is by this driving transistors and the discharge of this Organic Light Emitting Diode, and this second end of keeping storage capacitors is at this second predeterminated voltage; And

In a glow phase, this first predeterminated voltage this first end to this storage capacitors is provided again, make this first switching transistor be in cut-off state, and this second end of this storage capacitors is communicated with this grid of this driving transistors, to such an extent as to that this driving transistors drives this Organic Light Emitting Diode is shinny;

Wherein, in the process that drives this second pixel, also comprise step: in this write phase, by this first switching transistor this data voltage is provided to this grid of this driving transistors at this data line, this data line provides this grid to this driving transistors by this first switching transistor with a pre-charge pressure; This pre-charge pressure, moment that this first switching transistor from this first pixel is cut off after this write phase to this first switching transistor of this second pixel before this write phase is switched on, be provided to this data line; And this pre-charge pressure is greater than providing to the critical voltage sum of this driving transistors of this data voltage of this grid of this driving transistors of this second pixel and this second pixel.

12. image element driving method according to claim 11, it is characterized in that, each pixel in this first pixel and this second pixel also comprises a second switch transistor and one the 3rd switching transistor, this second switch transistor is electrically coupled between this first end of this first predeterminated voltage and this storage capacitors, and when the 3rd switching transistor is electrically coupled between this second end of this second predeterminated voltage and this storage capacitors, aforementioned in this reset phase, this first predeterminated voltage this first end to this storage capacitors is provided, and provides this second predeterminated voltage to the step of this second end of this storage capacitors to comprise:

By this first switching transistor, and this second switch transistor AND gate the 3rd switching transistor of conducting.

13. image element driving method according to claim 12 is characterized in that, the transistorized conduction and cut-off state of this first switching transistor and this second switch is determined by same control signal.

14. image element driving method according to claim 12, it is characterized in that, each pixel in this first pixel and this second pixel further comprises one the 4th switching transistor, and when the 4th switching transistor is electrically coupled between this grid of this second end of this storage capacitors and this driving transistors, aforementioned in this write phase, make this data line provide this grid with this data voltage to this driving transistors by this first switching transistor, and this first end that makes this storage capacitors is by this driving transistors and the discharge of this Organic Light Emitting Diode, and this second end of keeping storage capacitors comprises in the step of this second predeterminated voltage:

This first switching transistor of conducting by this second switch transistor, makes the 3rd switching transistor be in conducting state and makes the 4th switching transistor be in cut-off state.

15. image element driving method according to claim 14 is characterized in that, the conduction and cut-off state of the 3rd switching transistor and the 4th switching transistor is determined by same control signal.

16. image element driving method according to claim 14, it is characterized in that, aforementioned in this glow phase, this first predeterminated voltage this first end to this storage capacitors is provided again, make this first switching transistor be in cut-off state, and this second end of this storage capacitors is communicated with this grid of this driving transistors, to such an extent as to driving the shinny step of this Organic Light Emitting Diode, this driving transistors comprises:

By this first switching transistor, this second switch transistor of conducting, by the 3rd switching transistor and conducting the 4th switching transistor.

17. image element driving method according to claim 11, it is characterized in that, when this active matrix organic LED display comprises that also a demultiplexer and this data line are electrically coupled to an output terminal of this demultiplexer, in the process that drives this second pixel, further comprise step:

This demultiplexer of activation is to provide this pre-charge pressure to this data line by this demultiplexer; And

This demultiplexer of activation once more is to change into this data voltage by this demultiplexer with this pre-charge pressure of this data line.

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