Patent Publication Number: US-10325555-B2

Title: Organic light emitting pixel compensation circuit, organic light emitting display panel, and method for driving the panel

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to and claims priority from Chinese Patent Application No. 201611126639.X, filed on Dec. 9, 2016, entitled “Organic Light Emitting Pixel Compensation Circuit, Organic Light Emitting Display Panel, and Method for Driving the Panel,” the entire disclosure of which is hereby incorporated by reference for all purposes. 
     TECHNICAL FIELD 
     The present application relates to the field of display technology, and particularly to an organic light emitting pixel compensation circuit, an organic light emitting display panel, and a driving method. 
     BACKGROUND 
     With the development of display technologies, liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays, as two types of popular display devices, are more widely used in various portable electronic devices. 
     LCD is a non-self-luminous device, and OLED is an organic self-luminous device. Compared with the LCD, the OLED display has faster response speed, higher contrast and wider viewing angle, so the OLED display receives more attention. 
     However, in a conventional OLED display, generally only the threshold voltage of a driving transistor of the light emitting diode is compensated, without considering the impact from the deterioration of the light emitting element. For example, as time passes, the forward voltage drops across the light-emitting element (the lowest forward voltage at which the light-emitting element can be turned on at a prescribed forward current) is increased when the current flows through the light-emitting element. The light-emitting element is usually connected to a source and a drain of the driving transistor. As a result, the potential difference between the source and drain of the driving transistor decreases. Therefore, the light-emitting current flowing through the light-emitting element also decreases, resulting in display anomalies. 
     In view of the defects or disadvantages existing in the conventional OLED drivers, it is desirable to provide an organic light emitting pixel compensation circuit, an organic light emitting display panel, and a driving method, to solve the existing technical problems. 
     SUMMARY 
     According to an aspect of the present application, an organic light emitting pixel compensation circuit is provided, which includes an external compensation module comprising a data line, a reference voltage line, a reset control line, a first detection control line, a second detection control line, a first input/output terminal, a second input/output terminal, a reset unit, a threshold voltage detection unit, a deterioration voltage detection unit, a data processing unit, and an adder unit. The reset unit is connected to the reference voltage line, the second input/output terminal, and configured to transmit a signal provided from the reference voltage line to the second input/output terminal, based on a signal from the reset control line. The threshold voltage detection unit is connected to the data line, the first input/output terminal, and the data processing unit, and configured to transmit a voltage on the first input/output terminal to the data processing unit, based on a signal from the first detection control line. The deterioration voltage detection unit is connected to the second input/output terminal and the data processing unit, and configured to transmit a voltage on the second input/output terminal to the data processing unit, based on a signal from the second detection control line. The data processing unit is connected to the threshold voltage detection unit, the deterioration voltage detection unit, and the adder unit, and configured to process the voltages provided from the threshold voltage detection unit and the deterioration voltage detection unit, and transmit the processed voltages to the adder unit. The adder unit is connected to the data processing unit and the data line, and configured to provide a compensated voltage, based on the voltage provided from the data processing unit and the voltage on the data line. 
     According to another aspect of the present application, an organic light emitting display panel is also provided, which includes a display region and a non-display region surrounding the display region. A plurality of external compensation modules is arranged in the non-display region. Each of the external compensation modules includes a data line, a reference voltage line, a reset control line, a first detection control line, a second detection control line, a first input/output terminal, a second input/output terminal, a reset unit, a threshold voltage detection unit, a deterioration voltage detection unit, a data processing unit, and an adder unit. The reset unit is connected to the reference voltage line and the second input/output terminal, and configured to transmit a signal provided from the reference voltage line to the second input/output terminal, based on a signal from the reset control line. The threshold voltage detection unit is connected to the data line, the first input/output terminal, and the data processing unit, and configured to transmit a voltage on the first input/output terminal to the data processing unit, based on a signal from the first detection control line. The deterioration voltage detection unit is connected to the second input/output terminal and the data processing unit, and configured to transmit a voltage on the second input/output terminal to the data processing unit, based on a signal from the second detection control line. The data processing unit is connected to the threshold voltage detection unit, the deterioration voltage detection unit, and the adder unit, and configured to process the voltages provided from the threshold voltage detection unit and the deterioration voltage detection unit, and transmit the processed voltages to the adder unit. The adder unit is connected to the data processing unit and the data line, and configured to provide a compensated voltage, based on the voltage provided from the data processing unit and the voltage on the data line. 
     According to another aspect of the present application, a method for driving an organic light emitting display panel is further provided. The method includes the following. During initialization, a data line provides a data voltage, a reference voltage line provides a reference voltage, a first source voltage terminal provides a first voltage, a data voltage write unit transmits the data voltage to a gate of a driving transistor based on a signal from a first scan line, a reset detection control unit is turned on based on a signal from a second scan line, a reset unit transmits the reference voltage to an anode of a light emitting element based on a signal from a reset control line, and a light emission control unit transmits the first voltage to a first electrode of the driving transistor based on a signal from a light emission control line. During detection of a threshold voltage, the light emission control unit is turned off based on a signal from the light emission control line, the voltage on the first electrode of the driving transistor is transmitted via a first input/output terminal to a threshold voltage detection unit, and the threshold voltage detection unit implements the detection on the driving transistor based on a signal from the first detection control line. During writing of the first voltage, the threshold voltage detection unit is turned off based on a signal from the first detection control line, the reset unit is turned off based on a signal from the reset control line, a data processing unit processes the detected voltage to obtain a threshold voltage, an adder unit performs compensation on the data voltage based on the threshold voltage, and the data voltage write unit transmits the compensated data voltage to the gate of the driving transistor based on a signal from the first scan line. During detection of a deterioration voltage, the light emission control unit is turned on based on a signal from the light emission control line, an anode voltage of the light emitting element is transmitted to a second input/output terminal, and a deterioration voltage detection unit implements the detection on the light emitting element based on a signal from a second detection control line. During writing of a second voltage, the light emission control unit is turned off based on a signal from the light emission control line, the deterioration voltage detection unit is turned off based on a signal from the second detection control line, the data processing unit processes the detected anode voltage to obtain a deterioration voltage, the adder unit performs compensation on the data voltage based on the deterioration voltage, and the data voltage write unit transmits the compensated data voltage to the gate of the driving transistor based on a signal from the first scan line. During light emission, the data voltage write unit is turned off based on a signal from the first scan line, the reset detection control unit is turned off based on a signal from the second scan line, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light. 
     According to the solutions provided in the present application, the anode voltage of the second input/output terminal is detected and processed to produce a compensated voltage, and the compensated voltage is fed via the data line back to the gate of the driving transistor, thereby achieving the deterioration compensation for the light emitting element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features, objects, and advantages of the present application will become more apparent upon reading of the following detailed description of the non-limiting embodiments with reference to the accompanying drawings. 
         FIG. 1A  shows a schematic diagram of an embodiment of an organic light emitting pixel compensation circuit according to the present application; 
         FIG. 1B  shows a schematic diagram of another embodiment of an organic light emitting pixel compensation circuit according to the present application; 
         FIG. 2A  shows a schematic diagram of an implementation of the organic light emitting pixel compensation circuit shown in  FIG. 1A ; 
         FIG. 2B  shows a schematic diagram of an implementation of the organic light emitting pixel compensation circuit shown in  FIG. 1B ; 
         FIG. 3  shows a schematic diagram of an embodiment of an organic light emitting display panel according to the present application; 
         FIG. 4  shows a timing diagram of the organic light emitting display panel shown in  FIG. 3 ; 
         FIGS. 5A to 5F  show equivalent schematic diagrams of the organic light emitting pixel compensation circuit on the organic light emitting display panel shown in  FIG. 3  in various stages shown in  FIG. 4 ; 
         FIG. 6  shows a schematic diagram of another embodiment of an organic light emitting display panel according to the present application; 
         FIG. 7  shows a schematic diagram of another embodiment of an organic light emitting display panel according to the present application; and 
         FIG. 8  shows a schematic flow chart of a method for driving the organic light emitting display panels according to various embodiments of the present application. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present application will be further described below in detail in combination with the accompanying drawings and the embodiments. It should be appreciated that the specific embodiments described herein are merely used for explaining the relevant invention, rather than limiting the invention. In addition, it should be noted that, for the ease of description, only the parts related to the relevant invention are shown in the accompanying drawings. 
     It should also be noted that the embodiments in the present application and the features in the embodiments may be combined with each other on a non-conflict basis. The present application will be described below in detail with reference to the accompanying drawings and in combination with the embodiments. 
       FIG. 1A  shows a schematic diagram of an embodiment of an organic light emitting pixel compensation circuit according to the present application. 
     As shown in  FIG. 1A , an organic light emitting pixel compensation circuit  100   a  may include an external compensation module  11   a , and the external compensation module  11   a  includes a data line Data, a reference voltage line Ref, a reset control line SW 3 , a first detection control line SW 1 , a second detection control line SW 2 , a first input/output terminal  101 , a second input/output terminal  102 , a reset unit  113 , a threshold voltage detection unit  111 , a deterioration voltage detection unit  112 , a data processing unit  114 , and an adder unit  115 . 
     The reset unit  113  is connected to the reference voltage line Ref and the second input/output terminal  102 , and configured to transmit a signal provided from the reference voltage line Ref to the second input/output terminal  102 , based on a signal from the reset control line SW 3 . The threshold voltage detection unit  111  is connected to the data line Data, the first input/output terminal  101  and the data processing unit  114 , and configured to transmit a voltage signal on the first input/output terminal  101  to the data processing unit  114  based on a signal from the first detection control line SW 1 . The deterioration voltage detection unit  112  is connected to the second input/output terminal  102  and the data processing unit  114 , and configured to transmit a voltage signal on the second input/output terminal  102  to the data processing unit  114  based on a signal from the second detection control line SW 2 . The data processing unit  114  is connected to the threshold voltage detection unit  111 , the deterioration voltage detection unit  112 , and the adder unit  115 , and configured to process the voltage signals provided from the threshold voltage detection unit  111  and the deterioration voltage detection unit  112 , and transmit the processed voltage signals to the adder unit  115 . The adder unit  115  is connected to the data processing unit  114 , and the data line Data, and configured to provide a compensated voltage signal based on the voltage signal provided from the data processing unit  114  and the voltage signal on the data line Data. 
     In this embodiment, the threshold voltage detection unit  111  detects a threshold voltage of a driving transistor in an organic light emitting pixel from the first input/output terminal  101 , and a compensated data voltage is fed back to the data line Data after the processing by the data processing unit  114  and the addition by the adder unit  115 . In this way, the threshold voltage of the organic light emitting pixel is compensated. Meanwhile, the deterioration voltage detection unit  112  detects an anode voltage signal of a light emitting element in an organic light emitting pixel from the second input/output terminal  102 , and a compensated data voltage is fed back to the data line Data after the processing by the data processing unit  114  and the addition by the adder unit  115 . In this way, deterioration compensation is performed on the light emitting element of the organic light emitting pixel. 
     The organic light emitting pixel compensation circuit  100   a  may further include a plurality of internal compensation modules  12   a , and each of the internal compensation modules  12   a  may include a data voltage storage unit  121 , a data voltage write unit  122 , a reset detection control unit  123 , a light emission control unit  124 , a light emitting element D 1 , a driving transistor DT, a light emission control line SW 4 , a first scan line S 1 , and a second scan line S 2 . 
     The data voltage storage unit  121  is connected to a gate of the driving transistor DT, and configured to store a gate voltage signal of the driving transistor DT. The data voltage write unit  122  is connected to the data line Data and the gate of the driving transistor DT, and configured to transmit a signal from the data line Data to the gate of the driving transistor DT based on a signal from the first scan line S 1 . The reset detection control unit  123  is connected to an anode of the light emitting element D 1  and the second input/output terminal  102 , and configured to transmit an anode voltage signal of the light emitting element D 1  to the second input/output terminal  102  or transmit a voltage signal of the second input/output terminal  102  to the anode of the light emitting element D 1 , based on a signal from the second scan line S 2 . The light emission control unit  124  is connected to a first source voltage terminal VDD and a first electrode of the driving transistor DT, and configured to control the light emission of the light emitting element D 1 , based on a signal from the light emission control line SW 4 . A cathode of the light emitting element D 1  is connected to a second source voltage terminal VEE. A second electrode of the driving transistor DT is connected to the anode of the light emitting element D 1 , and the first electrode of the driving transistor DT is connected to the first input/output terminal  101 . 
     The internal compensation module  12   a  may transmit a voltage signal including the threshold voltage of the driving transistor DT to the first input/output terminal  101 , and then a compensated data voltage is transmitted to the gate of the driving transistor DT via the data line Data, to accomplish the compensation on the threshold voltage. In addition, the internal compensation module  12   a  may further transmit a voltage signal including the anode voltage of the light emitting element D 1  to the second input/output terminal  102 , and then a compensated data voltage is transmitted to the gate of the driving transistor DT via the data line Data, to accomplish the deterioration compensation. 
       FIG. 1B  shows a schematic diagram of another embodiment of an organic light emitting pixel compensation circuit according to the present application. 
     The structure of the embodiment shown in  FIG. 1B  is largely the same as that of the embodiment shown in  FIG. 1A . In the following description, the same parts as those in the embodiment shown in  FIG. 1A  will be omitted and the differences are highlighted. 
     Unlike the embodiment shown in  FIG. 1A , in an organic light emitting pixel compensation circuit  100   b , the light emission control line SW 4  and a light emission control unit  116  may be arranged in an external compensation module  11   b , as shown in  FIG. 1B . 
     The light emission control unit  116  is connected to the first source voltage terminal VDD and the first input/output terminal  101 , and configured to transmit a voltage signal of the first source voltage terminal VDD to the first input/output terminal  101 , based on a signal from the light emission control line SW 4 . 
     In this embodiment, because the light emission control line SW 4  and the light emission control unit  116  are arranged in the external compensation module  11   b , the circuit structure of the internal compensation module  12   b  is simplified, and the area occupied by the internal compensation module  12   b  is reduced, which facilitates the increase in the aperture ratio of the organic light emitting pixel, and the fabrication of an organic light emitting display panel with a high PPI. 
       FIG. 2A  shows a schematic diagram of an implementation of the organic light emitting pixel compensation circuit  100   a  shown in  FIG. 1A .  FIG. 2B  shows a schematic diagram of an implementation of the organic light emitting pixel compensation circuit  100   b  shown in  FIG. 1B . 
     An organic light emitting pixel compensation circuit  200   a  shown in  FIG. 2A  is a specific implementation of the organic light emitting pixel compensation circuit  100   a  shown in  FIG. 1A . Therefore, the organic light emitting pixel compensation circuit  200   a  may similarly include an external compensation module  21   a  and a plurality of internal compensation modules  22   a . The external compensation module  21   a  may similarly include a data line Data, a reference voltage line Ref, a reset control line SW 3 , a first detection control line SW 1 , a second detection control line SW 2 , a first input/output terminal  201 , a second input/output terminal  202 , a reset unit  213 , a threshold voltage detection unit  211 , a deterioration voltage detection unit  212 , a data processing unit  214 , and an adder unit  215 . Each of the internal compensation modules  22   a  may similarly include a data voltage storage unit  221 , a data voltage write unit  222 , a reset detection control unit  223 , a light emission control unit  224 , a light emitting element D 1 , a driving transistor DT, a light emission control line SW 4 , a first scan line S 1 , and a second scan line S 2 . 
     The implementation shown in  FIG. 2A  differs from the embodiment shown in  FIG. 1A  in that the structures of the threshold voltage detection unit  211 , the deterioration voltage detection unit  212 , the reset detection control unit  223 , the reset unit  213 , the data voltage storage unit  221 , the data voltage write unit  222  and the light emission control unit  224  are specifically described. 
     The threshold voltage detection unit  211  may include a first switch transistor T 1  and a first capacitor C 1 . A gate of the first switch transistor T 1  is connected to the first detection control line SW 1 , a first electrode of the first switch transistor T 1  is connected to the first input/output terminal  201 , a second terminal of the first capacitor C 1  is grounded, and a second electrode of the first switch transistor T 1  and a first terminal of the first capacitor C 1  are connected to the data processing unit  214 . 
     The deterioration voltage detection unit  212  may include a second switch transistor T 2  and a second capacitor C 2 . A gate of the second switch transistor T 2  is connected to the second detection control line SW 2 , a first electrode of the second switch transistor T 2  and a first terminal of the second capacitor C 2  are connected to the second input/output terminal  202 , a second terminal of the second capacitor C 2  is grounded, and a second electrode of the second switch transistor T 2  is connected to the data processing unit  214 . 
     The reset detection control unit  223  may include a third switch transistor T 3 . A gate of the third switch transistor T 3  is connected to the second scan line S 2 , a first electrode of the third switch transistor T 3  is connected to the second input/output terminal  202 , and a second electrode of the third switch transistor T 3  is connected to an anode of the light emitting element D 1 . 
     The reset unit  213  may include a fourth switch transistor T 4 . A gate of the fourth switch transistor T 4  is connected to the reset control line SW 3 , a first electrode of the fourth switch transistor T 4  is connected to the reference voltage line Ref, and a second electrode of the fourth switch transistor T 4  is connected to the second input/output terminal  202 . 
     The organic light emitting pixel compensation circuit  200   a  may further include a common voltage line Vcom. The data voltage storage unit  221  includes a third capacitor C 3 , and the data voltage write unit  222  includes a fifth switch transistor T 5 . A first terminal of the third capacitor C 3  is connected to a gate of the driving transistor DT, a second terminal of the third capacitor C 3  is connected to the common voltage line Vcom, a gate of the fifth switch transistor T 5  is connected to the first scan line S 1 , a first electrode of the fifth switch transistor T 5  is connected to the data line Data, and a second electrode of the fifth switch transistor T 5  is connected to the gate of the driving transistor DT. 
     The light emission control unit  224  may include a sixth switch transistor T 6 . A gate of the sixth switch transistor T 6  is connected to the light emission control line SW 4 , a first electrode of the sixth switch transistor T 6  is connected to the first source voltage terminal VDD, a second electrode of the sixth switch transistor T 6  is connected to a first electrode of the driving transistor DT. 
     The organic light emitting pixel compensation circuit  200   b  shown in  FIG. 2B  is a specific implementation of the organic light emitting pixel compensation circuit  100   b  shown in  FIG. 1B . The structure of the organic light emitting pixel compensation circuit  200   b  shown in  FIG. 2B  is largely the same as that of the organic light emitting pixel compensation circuit  200   a  shown in  FIG. 2A . In the following description, the same parts as those in the organic light emitting pixel compensation circuit  200   a  shown in  FIG. 2A  will be omitted and the differences are highlighted. 
     Unlike the organic light emitting pixel compensation circuit  200   a  shown in  FIG. 2A , no light emission control unit is arranged in an internal compensation module  22   b , and the light emission control line SW 4  and a light emission control unit  216  may be arranged in an external compensation module  21   b , as shown in  FIG. 2B . 
     The light emission control unit  216  may include a sixth switch transistor T 6 . A gate of the sixth switch transistor T 6  is connected to the light emission control line SW 4 , a first electrode of the sixth switch transistor T 6  is connected to the first source voltage terminal VDD, a second electrode of the sixth switch transistor T 6  is connected to the first input/output terminal  201 . 
     Although the first switch transistor T 1 , the second switch transistor T 2 , the third switch transistor T 3 , the fourth switch transistor T 4 , the fifth switch transistor T 5 , the sixth switch transistor T 6 , and the driving transistor DT shown in  FIGS. 2A and 2B  are all PMOS transistors, and the third capacitor C 3  is connected to the common voltage line Vcom, these are merely exemplary. It should be understood that all or some of the first switch transistor T 1 , the second switch transistor T 2 , the third switch transistor T 3 , the fourth switch transistor T 4 , the fifth switch transistor T 5 , the sixth switch transistor T 6 , and the driving transistor DT may be an NMOS (Negative channel Metal Oxide Semiconductor) transistor, and the third capacitor C 3  may be connected to the first electrode or the second electrode of the driving transistor DT. These may be set by a person skilled in the art according to the needs in practical application scenarios. 
     Optionally, the organic light emitting pixel compensation circuit may further include a threshold voltage storage unit and a deterioration voltage storage unit connected to the data processing unit. 
     As shown in  FIG. 1A , the organic light emitting pixel compensation circuit  100   a  may further include a threshold voltage storage unit  117  and a deterioration voltage storage unit  118 . The threshold voltage storage unit  117  is connected to the data processing unit  114 , and configured to store the threshold voltage provided from the data processing unit  114 . The deterioration voltage storage unit  118  is connected to the data processing unit  114 , and configured to store the deterioration voltage provided from the data processing unit  114 . 
     For example, after the threshold compensation is performed on the driving transistor DT in the organic light emitting pixel compensation circuit  100   a , the threshold voltage may be stored in the threshold voltage storage unit; and after the deterioration compensation is performed on the light emitting element D 1  in the organic light emitting pixel compensation circuit  100   a , the deterioration voltage may be stored in the deterioration voltage storage unit. 
     As such, before the data processing unit transmits the threshold voltage to the adder unit, the threshold voltage is compared with that stored in the threshold voltage storage unit. If the threshold voltage is different from that stored in the threshold voltage storage unit, the threshold voltage is transmitted to the adder unit, for compensating the threshold voltage of the driving transistor. 
     Similarly, before the data processing unit transmits the deterioration voltage to the adder unit, the deterioration voltage is compared with that stored in the deterioration voltage storage unit. If the deterioration voltage is different from that stored in the deterioration voltage storage unit, the deterioration voltage is transmitted to the adder unit, for performing deterioration compensation on the light emitting element. 
     Optionally, the organic light emitting pixel compensation circuit may further include a driving circuitry, in which a lookup table memory is arranged, and configured to store current-voltage characteristic parameters of the light emitting element. 
     As shown in  FIG. 1A , the organic light emitting pixel compensation circuit  100   a  may further include a driving circuitry  110 , where a lookup table memory  119  is arranged, and configured to store current-voltage characteristic parameters of the light emitting element D 1 . 
     As such, during deterioration compensation at a later time, the data processing unit may transmit the anode voltage signal obtained by the deterioration voltage detection unit to the lookup table memory in the driving circuitry, and may look up the deterioration voltage of the light emitting element D 1 , and transmit the deterioration voltage to the adder unit for performing deterioration compensation on the light emitting element D 1 , thereby simplifying the process for processing the anode voltage signal by the data processing unit. 
       FIG. 3  shows a schematic diagram of an embodiment of an organic light emitting display panel according to the present application. 
     As shown in  FIG. 3 , an organic light emitting display panel  300  may include a display region  32  and a non-display region  31  surrounding the display region  32 . A plurality of external compensation modules  311  is arranged in the non-display region  31 , and each of the external compensation modules  311  has the same circuit structure as that of the external compensation module  21   a  shown in  FIG. 2A . 
     In this embodiment, the threshold voltage detection unit detects a threshold voltage of a driving transistor in an organic light emitting pixel from the first input/output terminal, and a compensated data voltage is fed back to the data line after the processing by the data processing unit and the addition by the adder unit. In this way, the threshold voltage of the organic light emitting pixel is always compensated. Meanwhile, the deterioration voltage detection unit detects an anode voltage signal of alight emitting element in an organic light emitting pixel from the second input/output terminal, and a compensated data voltage is fed back to the data line after the processing by the data processing unit and the addition by the adder unit. In this way, the deteriorated voltage of the organic light emitting pixel is compensated to remain constant. 
     The display region  32  may include a plurality of rows of pixel units  323  and a plurality of columns of pixel units  324 . Each row of the pixel units  323  may include a plurality of sub-pixels  322 , and each column of the pixel units  324  may include a plurality of sub-pixels  322 . An internal compensation module  321  may be arranged in each of the sub-pixels  322 , and the internal compensation module  321  may have the same circuit structure as that of the internal compensation module  22   a  shown in  FIG. 2A . 
     The internal compensation module  321  may transmit a voltage signal including the threshold voltage of the driving transistor to the first input/output terminal, and then a compensated data voltage from the external compensation module  311  is transmitted to the gate of the driving transistor via the data line, to accomplish the compensation on the threshold voltage. In addition, the internal compensation module  321  may further transmit a voltage signal including the anode voltage of the light emitting element to the second input/output terminal, and then a compensated data voltage from the external compensation module  311  is transmitted to the gate of the driving transistor via the data line, to accomplish the deterioration compensation. 
     The working principle of the organic light emitting display panel  300  shown in  FIG. 3  is described by way of examples in which the first switch transistor, the second switch transistor, the third switch transistor, the fourth switch transistor, the fifth switch transistor, the sixth switch transistor and the driving transistor are all PMOS transistors, with reference to the circuit diagram shown in  FIG. 2A , the timing diagram shown in  FIG. 4 , and the equivalent circuit diagrams shown in  FIGS. 5A to 5F . 
     The timing diagram in  FIG. 4  is divided in 6 stages P 1  to P 6 . Stage P 1 : The data line Data provides a data voltage signal V data , the reference voltage line Ref provides a reference voltage signal V ref , and the first source voltage terminal VDD in  FIG. 5A  provides a first voltage signal Vdd. The first scan line S 1 , the second scan line S 2 , the reset control line SW 3 , and the light emission control line SW 4  are set at a low level signal. and The fifth switch transistor T 5  connected to S 1 , the third switch transistor T 3  connected to S 2 , the sixth switch transistor T 6  connected to SW 4 , the fourth switch transistor T 4  connected to SW 3 , and the driving transistor DT connected to N 2 , are turned on (for PNP type transistors). 
     An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5A . 
     In this stage, the potential V g  at the gate (that is, the node N 2 ) of the driving transistor DT is V data , the potential V s  at a source (that is, the first electrode or the node N 1  of the driving transistor DT) of the driving transistor DT is Vdd, and the anode potential V oled+  of the light emitting element D 1  is V ref . 
     Stage P 2 : The light emission control line SW 4  provides a high level signal, the first detection control line SW 1  provides a low level signal, the sixth switch transistor T 6  connected to SW 4  is turned off, and the first switch transistor T 1  connected to SW 1  is turned on. An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5B . 
     In this stage, the source of the driving transistor DT discharges to the first capacitor C 1 , the source potential V s  is gradually decreased from Vdd to V data +|V th |, the discharge is stopped, and the source potential V s  is maintained by the first capacitor C 1 . Here, V th  is the threshold voltage of the driving transistor DT. 
     Stage P 3 : The first detection control line SW 1  and the reset control line SW 3  provide a high level signal, and the first switch transistor T 1  connected to SW 1  and the fourth switch transistor T 4  connected to SW 3  are turned off. An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5C . 
     In this stage, the data processing unit  214  acquires the source potential V s  from the first capacitor C 1 , acquires the voltage signal V data  from the data line Data and processes them (for example, performs subtraction of the two voltage signals, V s −V data ), to obtain the threshold voltage |V th |, and transmit the threshold voltage |V th | to the adder unit  215 . After addition by the adder unit  215 , a compensated data voltage signal V data ′ (V data ′=V data −|V th |) is fed back to the gate (that is, the node N 2 ) of the driving transistor DT via the data line Data. The compensated data voltage signal V data ′ is maintained by the third capacitor C 3 . 
     Stage P 4 : The second detection control line SW 2  and the light emission control line SW 4  provide a low level signal, and the second switch transistor T 2  connected to SW 2 , the sixth switch transistor T 6  connected to SW 4 , and the driving transistor DT, connected to N 1  at its source, are turned on. An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5D . 
     In this stage, the potential V s  at the source (that is, the node N 1 ) of the driving transistor DT is Vdd, the potential V g  at the gate (that is, the node N 2 ) of the driving transistor DT is V data ′, and the anode potential V oled+  of the light emitting element D 1  is transmitted through the third switch transistor T 3  and the second switch transistor T 2  to the data processing unit  214 . 
     A transistor&#39;s current in a saturated region is calculated by the formula:
 
 I=k (| V   gs   |−|V   th |) 2 (1+λ· V   ds )  (1)
 
Therefore the light-emitting current flowing through the light-emitting element D 1  in Stage P 4  is calculated to be:
 
 I   oled   =k ( Vdd−V   data   ′−|V   th |) 2 (1+λ( Vdd−V   oled+ ))  (2)
 
     where V gs  is the potential difference between the gate and the source of the driving transistor DT, V ds  is the potential difference between the source and the drain (the second electrode of the driving transistor DT) of the driving transistor DT, and λ is a channel length modulation parameter; k is calculated from: 
     
       
         
           
             
               k 
               = 
               
                 
                   1 
                   2 
                 
                 ⁢ 
                 μ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   c 
                   ox 
                 
                 ⁢ 
                 
                   w 
                   l 
                 
               
             
             ; 
           
         
       
     
     where μ is the channel mobility of the driving transistor DT, c ox  is the gate oxide capacitance per unit area of the driving transistor DT, and 
             w   l         
is width-to-length ratio of the channel of the driving transistor DT.
 
     By simplifying Formula (2), the light-emitting current flowing through the light-emitting element D 1  in Stage P 4  is
 
 I   oled   =k ( Vdd−V   data ) 2 (1+λ( Vdd−V   oled+ ))  (3)
 
     It can be seen from Formula (3) that the light-emitting current I oled  is independent of the threshold voltage V th  of the driving transistor DT. Therefore, in case that the anode voltage Vdada of the light emitting element D 1  is kept unchanged, the constant light-emitting current I oled  can be obtained as long as the first voltage signal Vdd and data voltage signal V data  are applied to the organic light emitting display panel  300  in this embodiment, thereby avoiding the influence of the threshold voltage V th  of the driving transistor DT on the light emitting current I oled . As a result, the display unevenness due to the threshold difference of the driving transistor DT is avoided. 
     In Stage P 5 , the second detection control line SW 2  and the light emission control line SW 4  provide a high level signal, and the second switch transistor T 2  connected to SW 2  and the sixth switch transistor T 6  connected to SW 4  are turned off. An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5E . 
     The external data processing unit  214  processes the anode voltage signal V oled+ , to obtain a deterioration voltage ΔV oled  of the light emitting element D 1 , and transmits the obtained deterioration voltage ΔV oled  to the external adder unit  215 . After addition by the adder unit  215 , a compensated data voltage signal V data ″ (V data ″=V data −|V th |−ΔV oled ) is fed back to the gate (that is, the node N 2 ) of the driving transistor DT via the data line Data, and the compensated data voltage V data ″ is therefore maintained by the third capacitor C 3 . 
     A process for processing the anode voltage signal V oled+  by the data processing unit  214  to obtain the deterioration voltage ΔV oled  is as described below. A forward voltage V oled  (V oled =V oled −Vee, where Vee is a voltage signal provided by the second source voltage terminal VEE) of the light emitting element D 1  is calculated; a current value corresponding to the forward voltage V oled  of the light emitting element D 1  is obtained based on the previously stored current-voltage characteristic parameters of the light emitting element; the brightness of the light emitting element D 1  is calculated from the current value; and if the decay of the brightness of the light emitting element D 1  (relative to the original brightness of the light emitting element D 1 ) exceeds a preset value (for example, 3%), deterioration compensation of the light emitting element is needed, and a deterioration voltage ΔV oled  is obtained based on the previously stored current-voltage characteristic parameters of the light emitting element. 
     In stage P 6 , the first scan line S 1  and the second scan line S 2  provide a high level signal, the light emission control line SW 4  provides a low level signal, the fifth switch transistor T 5  and the third switch transistor T 3  are turned off, the sixth switch transistor T 6  and the driving transistor DT are turned on, and the light emitting element D 1  emits light. An equivalent circuit diagram of the organic light emitting pixel compensation circuit  200   a  is as shown in  FIG. 5F . 
     The potential V s  at the source (that is, the node N 1 ) of the driving transistor DT is Vdd, the potential V g  at the gate (that is, the node N 2 ) of driving transistor DT is V data ″, and the light emitting current flowing through the light emitting element D 1  is
 
 I   oled   =k ( Vdd−V   data   +ΔV   oled ) 2 (1+λ( Vdd−V   oled+ ))  (4)
 
     As can be known from comparison of Formulas (3) and (2), after deterioration compensation of the light emitting element D 1 , the light emitting current I oled  is increased. In case of brightness decay of the organic light emitting display panel  300  according to this embodiment after long time of use, the light emitting current is increased by means of deterioration compensation, thereby avoiding the brightness decay caused by deterioration of the light emitting element D 1 , and effectively extending the service life of the organic light emitting display panel  300 . 
     The sixth switch transistor T 6  and the light emission control line SW 4  may be arranged in the internal compensation module  321  of the sub-pixel  322 , and the light emission control lines SW 4  of the sub-pixels  322  in the same row of pixel units  323  are connected together. That is to say, the sixth switch transistors T 6  in the same row of pixel units  323  may share a common light emission control line SW 4 , and the first voltage signal Vdd controls the simultaneous light emission of the sub-pixels  322  in the same row of pixel units  323 , based on a signal from the light emission control line SW 4 . 
     As such, the threshold voltage of the driving transistor DT and the deterioration voltage of the light emitting element D 1  can be compensated with one row of pixel units  323  as a unit, thereby increasing the signal processing speed. 
     The internal compensation modules  321  in the sub-pixels  322  of the same column of pixel units  324  may be connected to the same external compensation module  311 . 
     At least two adjacent columns of the pixel units  324  may be connected to a same reference voltage line. The sub-pixels  322  in at least two adjacent columns of the pixel units  324  may share a common reference voltage line Ref, whereby wiring of the reference voltage line Ref in the sub-pixel  322  is reduced. Correspondingly, at least two adjacent external compensation modules  311  may share a common reset unit (not shown), which simplifies the circuit structure of the external compensation module, and reduces the area occupied by the external compensation module  311 . 
     Optionally, the external compensation modules  311  may share a common data processing unit. Correspondingly, the external compensation modules  311  may share a common adder unit. In this manner, the circuit structure of the external compensation module  311  is further simplified, and the area occupied by the external compensation module  311  is further reduced. 
     Optionally, a threshold voltage storage unit (not shown) and a deterioration voltage storage unit (not shown) may also be arranged in the non-display region  31  of the organic light emitting display panel  300 . The threshold voltage storage unit is connected to the data processing unit, and configured to store the threshold voltage provided by the data processing unit; and the deterioration voltage storage unit is connected to the data processing unit, and configured to store the deterioration voltage provided by the data processing unit. 
     For example, in  FIG. 3  after threshold compensation is performed on the driving transistor in the sub-pixel  322 , the threshold voltage may be stored in the threshold voltage storage unit; and after deterioration compensation is performed on the light emitting element in the sub-pixel  322 , the deterioration voltage is stored in the deterioration voltage storage unit. 
     As such, before the data processing unit transmits the threshold voltage to the adder unit, the threshold voltage is compared with that stored in the threshold voltage storage unit. If the threshold voltage is different from that stored in the threshold voltage storage unit, the threshold voltage is transmitted to the adder unit, for compensating the threshold voltage of the driving transistor in the sub-pixel  322 . 
     Similarly, before the data processing unit transmits the deterioration voltage to the adder unit, the deterioration voltage is compared with that stored in the deterioration voltage storage unit. If the deterioration voltage is different from that stored in the deterioration voltage storage unit, the deterioration voltage is transmitted to the adder unit, for performing deterioration compensation on the light emitting element in the sub-pixel  322 . 
     Optionally, a driving circuitry (not shown) is further arranged in the non-display region  31  of the organic light emitting display panel  300 , in which a lookup table memory is arranged, and configured to store current-voltage characteristic parameters of the light emitting element. 
     All the pixel units on the organic light emitting display panel may be pre-compensated (including threshold compensation and deterioration compensation), and the current-voltage characteristic parameters of the light emitting element before and after compensation are stored in the lookup table memory. 
     As such, during deterioration compensation at a later time, the data processing unit may transmit the anode voltage signal obtained by the deterioration voltage detection unit to the lookup table memory, to look up the deterioration voltage of the light emitting element, and transmit the deterioration voltage to the adder unit for performing deterioration compensation on the light emitting element in the sub-pixel  322 , thereby simplifying the process for processing the anode voltage signal by the data processing unit 
     In this embodiment, each row of the pixel units may be connected with one first scan line and one second scan line. 
     For example, in some application scenarios, the signals from the first scan lines S 1 -S m  and the signals from the second scan line S 1 ′-S m ′ are generated respectively by a shift register  33  and a shift register  34 , shown in  FIG. 3 . In these application scenarios, the signals from the first scan line S 1 -S m  may have the same waveform as scan line S 1  in  FIG. 4 , and the signal from the second scan line S 1 ′-S m ′ may have the same waveform as scan line S 2  in  FIG. 4 . 
     In addition, the internal compensation module  321  in each sub-pixel  322  on the organic light emitting display panel  300  includes, in addition to the driving transistor and the light emitting element, only three switch transistors (for example, the fifth switch transistor, the sixth switch transistor, and the third switch transistor) and one storage capacitor, the circuit structure is simple, and the threshold compensation and the deterioration compensation can be accomplished only by transmitting a voltage signal including the threshold voltage of the driving transistor and the anode voltage signal of the light emitting element to the external compensation module  311 . Therefore, the present invention is applicable to the organic light emitting display devices of various sizes. 
       FIG. 6  shows a schematic diagram of another embodiment of an organic light emitting display panel according to the present application. 
     The structure compensation circuitry of the embodiment shown in  FIG. 6  is largely the same as that of the embodiment shown in  FIG. 3 . A non-display region  61  of an organic light emitting display panel  600  also encloses a plurality of external compensation modules  611  arranged therein; and a display region  62  also include a plurality of rows of pixel units  623  and a plurality of columns of pixel units  624 . An internal compensation module  621  is also arranged in each sub-pixel  622  of the pixel unit  623 / 624 . 
     This embodiment in  FIG. 6  differs from the embodiment shown in  FIG. 3  in that one row of pixel units are connected with one scan line. 
     It can be known from the waveforms of S 1  and S 2  in  FIG. 4  that the first scan line and the second scan line may have the same waveform. Therefore, the first scan line and second scan line may share a common scan line. 
     Specifically, as shown in  FIG. 6 , the scan line S 1  may be connected to the data voltage write unit and the reset detection control unit of a first column of pixel units  623 , such that the data voltage write unit can transmit a signal from the data line to the gate of the driving transistor based on a signal from the scan line S 1 , and the reset detection control unit transmit the anode voltage of the light emitting element to the second input/output terminal or transmit the voltage of the second input/output terminal to the anode of the light emitting element, based on a signal from the scan line S 1 . Similarly, a scan line S m  is connected to the data voltage write unit and the reset detection control unit of an mth row of pixel units  623 . 
     Correspondingly, the scan lines S 1 -S m  may be provided by a shift register  63 , whereby the area occupied by the internal compensation module  621  is further reduced. 
       FIG. 7  shows a schematic diagram of another embodiment of an organic light emitting display panel according to the present application. 
     The structure of the circuitry of the embodiment shown in  FIG. 7  is largely the same as that of the embodiment shown in  FIG. 3 . A non-display region  72  of an organic light emitting display panel  700  also has a plurality of external compensation modules  711  arranged therein and a display region  72  also include a plurality of rows of pixel units  723  and a plurality of columns of pixel units  724 . An internal compensation module  721  is also arranged in each sub-pixel  722  of the pixel units  723 / 724 . 
     Unlike the embodiment shown in  FIG. 3 , in the organic light emitting display panel  700 , the sixth switch transistor T 6  and the light emission control line SW 4  may be arranged in the external compensation module  711 , each column of pixel units  724  may be connected to one sixth switch transistor T 6 , and each sixth switch transistor may share a common light emission control line SW 4 , as shown in  FIG. 7 . The first voltage signal Vdd can control the simultaneous light emission of all the sub-pixels  722  on the organic light emitting display panel  700 , based on a signal from the light emission control line SW 4 . 
     This embodiment has the following benefits. 
     On one hand, the sixth switch transistor T 6  and the light emission control line SW 4  are migrated from the internal compensation module  721  in each sub-pixel  722  of the display region  72  into the external compensation module  711  in the non-display region  71 , which not only simplifies the circuit structure of the internal compensation module  721 , but also reduces the area occupied by the internal compensation module  721  in the sub-pixel  722 , thus facilitating the increase in the aperture ratio of the sub-pixel  722 , and also the fabrication of an display panel with a high PPI. 
     On the other hand, the sixth switch transistor T 6  and the light emission control line SW 4  are arranged in the external compensation module  711 , and the sixth switch transistor T 6  and the light emission control line SW 4  are effectively multiplexed, which simplifies the circuit structure of the organic light emitting display panel  700 . 
     Moreover, because the first voltage signal Vdd can control the simultaneous light emission of all the sub-pixels  722  on the organic light emitting display panel  700  based on a signal from the light emission control line SW 4 , all the sub-pixels  722  on the organic light emitting display panel  700  can be collectively compensated. After all the sub-pixels  722  are compensated, all the sub-pixels  722  on the organic light emitting display panel  700  emit light based on a signal from the light emission control line SW 4 . In this way, visual discomforts caused by line-by-line scan, such as tailing and the like, are avoided. Particularly, when the display panel  700  is applied in a VR (Virtual Reality) device, the visual discomforts during scanning are avoided, thus eliminating the discomfort of a user such as dizziness and the like. 
     Moreover, the present application further discloses a method for driving an organic light emitting display panel, including the organic light emitting display panels according to various embodiments above. 
       FIG. 8  shows a schematic flow chart  800  of a method for driving an organic light emitting display panel of the present application in one frame period. 
     Step  801 : during initialization, a data line provides a data voltage signal, a reference voltage line provides a reference voltage signal, a first source voltage terminal provides a first voltage signal, a data voltage write unit transmits the data voltage signal to a gate of a driving transistor based on a signal from a first scan line, a reset detection control unit is turned on based on a signal from a second scan line, a reset unit transmits the reference voltage signal to an anode of a light emitting element based on a signal from a reset control line, and a light emission control unit transmits the first voltage signal to a first electrode of the driving transistor based on a signal from a light emission control line. 
     Step  802 : during detection of a threshold voltage, the light emission control unit is turned off based on a signal from the light emission control line, the voltage signal on the first electrode of the driving transistor is transmitted via a first input/output terminal to a threshold voltage detection unit, and the threshold voltage detection unit implements the detection on the driving transistor based on a signal from the first detection control line. 
     Step  803 : during writing the first voltage, the threshold voltage detection unit is turned off based on a signal from the first detection control line, the reset unit is turned off based on a signal from the reset control line, a data processing unit processes the detected voltage signal to obtain a threshold voltage, an adder unit performs compensation on the data voltage signal based on the threshold voltage, and the data voltage write unit transmits the compensated data voltage signal to the gate of the driving transistor based on a signal from the first scan line. 
     Step  804 : during detection of a deterioration voltage, the light emission control unit is turned on based on a signal from the light emission control line, an anode voltage signal of the light emitting element is transmitted to a second terminal, and a deterioration voltage detection unit implements the detection on the light emitting element based on a signal from a second detection control line. 
     Step  805 : during writing a second voltage, the light emission control unit is turned off based on a signal from the light emission control line, the deterioration voltage detection unit is turned off based on a signal from the second detection control line, the data processing unit processes the detected anode voltage signal to obtain a deterioration voltage, the adder unit performs compensation on the data voltage signal based on the deteriorated voltage, and the data voltage write unit transmits the compensated data voltage signal to the gate of the driving transistor based on a signal from the first scan line. 
     Step  806 : during light emission, the data voltage write unit is turned off based on a signal from the first scan line, the reset detection control unit is turned off based on a signal from the second scan line, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light 
     Here, when the method for driving an organic light emitting display panel according to this embodiment is used with an organic light emitting display panel (for example, the organic light emitting display panel  300  shown in  FIG. 3 , the organic light emitting display panel  600  shown in  FIG. 6 , and the organic light emitting display panel  700  shown in  FIG. 7 ) of the present application, the timing diagram of the signals in Steps  801  to  806  is as shown in  FIG. 4 . 
     Optionally, in the driving method according to this embodiment, the reference voltage signal is not higher than the second voltage signal provided from the second source voltage terminal. As a result, light emission of the light emitting element resulting from a leakage current formed due to the fact that the voltage signal applied to the anode of the light emitting element is larger than the voltage signal applied to the cathode of the light emitting element during initialization (see Stage P 1  shown in  FIG. 4 ) can be avoided, thereby improving the display effect of an organic light emitting display panel using the driving method of this embodiment in the dark state. 
     Optionally, in the driving method according to this embodiment, after each row of pixel units are compensated, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light. That is, by controlling an output signal from the light emission control line, the pixels in each row of pixel units enter a light emission stage simultaneously. 
     As such, the threshold voltage of the driving transistor and the deterioration voltage of the light emitting element can be compensated with one row of pixel units as a unit, thereby increasing the signal processing speed. 
     Optionally, in the driving method according to this embodiment, after all the sub-pixels on the organic light emitting display panel are compensated, the light emission control unit is turned on based on a signal from the light emission control line, and the light emitting element emits light. That is, by controlling an output signal from the light emission control line, all the sub-pixels on the organic light emitting display panel enter a light emission stage simultaneously. 
     Therefore, all the sub-pixels on the organic light emitting display panel can be compensated collectively, and after all the sub-pixels are compensated, all the sub-pixels on organic light emitting display panel emit light simultaneously. In this way, visual discomforts caused by line-by-line scan, such as tailing and the like, are avoided. Particularly, when the organic light emitting display panel of the present application is applied in a VR device, the visual discomforts caused during scanning are avoided, thus avoiding the discomfort of a user such as dizziness and the like. 
     It should be appreciated by those skilled in the art that the scope of the present application is not limited to the technical solutions formed by specific combinations of the above-mentioned technical features, but also cover other technical solutions formed by any combinations of the above-mentioned technical features or equivalent features thereof without departing from the concept of the present invention, such as, technical solutions formed by replacing the above-mentioned features with technical features with similar functions as (but not limited to) those disclosed in the present application.