Organic light emitting display panel, driving method thereof and organic light emitting display apparatus

This disclosure claims the benefit of Chinese Patent Application No. CN201710007312.9, filed on Jan. 5, 2017, entitled “Organic Light Emitting Display Panel, Driving Method thereof and Organic Light Emitting Display Apparatus,” the disclosure of which is incorporated herein by reference in its entirety.

The present disclosure relates to the field of display technology, and specifically relates to an organic light emitting display panel and a driving method thereof, and an organic light emitting display apparatus.

Utilizing the self-luminous property of organic semiconductor material for displaying, an organic light emitting display (OLED) has the advantages of, among others, high contrast and low power consumption. Typically, the display area of the organic light emitting display is provided with a pixel array composed of pixels and sub-pixels. Each sub-pixel contains an organic light emitting diode, driven by a pixel driving circuit to emit light.

A conventional pixel driving circuit may include a driving transistor which provides a light emitting current to an organic light emitting device under the control of a light emitting control signal. Since the light emitting current of the organic light emitting diode is related to a threshold voltage Vth of the driving transistor, the shifting of the threshold voltage Vth of the driving transistor (i.e., “threshold shift”) due to manufacture, aging after extended use, and other causes will result in the luminance of the organic light emitting device being unstable. In addition, in the conventional pixel driving circuit, the light emitting current of the organic light emitting diode is affected by a capacitance value thereof. Since capacitance values of organic light emitting diodes in different pixel driving circuits may not be the same, even if an identical data signal is provided, the luminances of various organic light emitting diodes will be different, resulting in reduced uniformity for the display luminance. Therefore, a solution for uniform display is needed.

The present disclosure provides an organic light emitting display panel and a driving method thereof, and an organic light emitting display apparatus to solve the technical problems mentioned in background section.

In a first aspect, the present disclosure provides an organic light emitting display panel including a plurality of pixel driving circuits arranged in a matrix of a plurality of rows and a plurality of columns, where the pixel driving circuit comprises a first scanning signal terminal, a second scanning signal terminal, a light emitting signal terminal, a data signal terminal, a first initialization signal terminal, a second initialization signal, a first voltage terminal, a second voltage terminal, a driving module, an initialization module, a data writing module, a light emitting control module and an organic light emitting diode. The driving module includes a driving transistor and a first capacitor, wherein the first capacitor includes a first electrode plate and a second electrode plate, wherein the first electrode plate electrically connects to a first electrode of the driving transistor, wherein a second electrode of the driving transistor electrically connects to the first voltage terminal, and wherein the driving transistor provides a light emitting current to an anode of the organic light emitting diode under the control of the light emitting control module. The initialization module electrically connects to a gate of the driving transistor and the first electrode of the driving transistor, for writing signals from the first initialization signal terminal and the second initialization signal terminal respectively to both the gate of the driving transistor and the first electrode of the driving transistor, under the control of the first scanning signal terminal and the second scanning signal terminal. The data writing module electrically connects to the second electrode plate of the first capacitor, for transmitting a signal of the data signal terminal to the second electrode plate of the first capacitor, under the control of the first scanning signal terminal. The light emitting control module comprises a first transistor, wherein a gate of the first transistor electrically connects to the light emitting signal terminal, a first electrode of the first transistor electrically connects to the second electrode plate of the first capacitor, and a second electrode of the first transistor electrically connects to the gate of the driving transistor. A cathode of the organic light emitting diode electrically connects to the second voltage terminal.

In a second aspect, the present disclosure provides a driving method applied to the organic light emitting display panel, comprising: in a first phase, providing a first level signal to the first scanning signal terminal and the second scanning signal terminal; providing a second level signal to the light emitting signal terminal; providing a first initialization signal to the first initialization signal terminal; providing a second initialization signal to the second initialization signal terminal; providing a data signal to the data signal terminal; writing by the initialization module the first initialization signal and the second initialization signal respectively into the gate and the first electrode of the driving transistor, transmitting the data signal to the second electrode plate of the first capacitor by the data writing module; in a second phase, providing the first level signal to the first scanning signal terminal; providing the second level signal to the second scanning signal terminal and the light emitting signal terminal; providing the first initialization signal to the first initialization signal terminal; providing the data signal to the data signal terminal; writing the first initialization signal into the gate of the driving transistor by the initialization module, transmitting the data signal to the second electrode plate of the first capacitor by the data writing module; turning on the driving transistor; charging the first electrode plate of the first capacitor by the first voltage terminal; in a third phase, providing the second level signal to the first scanning signal terminal and the second scanning signal terminal; providing the first level signal to the light emitting signal terminal; turning on the driving transistor and the first transistor; charging the first electrode of the driving transistor by the first voltage terminal; turning on the second electrode plate of the first capacitor and the gate of the driving transistor by the light emitting control module, wherein a potential of the gate of the driving transistor rises under the coupling of the first capacitor; and light emitting from the organic light emitting diode under a voltage difference between the gate and the first electrode of the driving transistor, the organic light emitting from the organic light emitting diode under a voltage difference between the gate and the first electrode of the driving transistor; wherein a voltage value of the first initialization signal is greater than a sum of a voltage value of the second initialization signal and a threshold voltage of the driving transistor; a voltage difference between the second initialization signal and the second voltage terminal is less than a break-over voltage of the organic light emitting diode.

In a third aspect, the present disclosure provides an organic light emitting display apparatus, including the organic light emitting display panel.

The organic light emitting display panel and the driving method thereof, and the organic light emitting display apparatus provided by the present disclosure may compensate the threshold voltage of the driving transistor while the potential of the node of the first capacitor connected to the first electrode of the driving transistor would not be changed by the coupling of the first capacitor, and the first capacitor does not cause the organic light emitting diode to divide the potential of the node of the first capacitor connected to the first electrode of the driving transistor to ensure that the potentials of the gate and the first electrode of the driving transistor are independent of the light emitting current and the capacitance values thereof of the organic light emitting diode, and the display luminance of each organic light emitting diode does not change abnormally due to the impact of its capacitance value, thereby improving the uniformity of the display luminance of the display panel and improving the display effect.

Other features, objectives and advantages of the present disclosure will become more apparent upon reading the detailed description to non-limiting embodiments with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic structural diagram of an embodiment of a pixel driving circuit in an organic light emitting display panel according to the present disclosure;

FIG. 2 is a schematic structural diagram of a specific circuit of the pixel driving circuit as shown in FIG. 1 ;

FIG. 3 is a schematic structural diagram of another specific circuit of the pixel driving circuit as shown in FIG. 1 ;

FIG. 4 is a schematic structural diagram of another specific circuit of the pixel driving circuit as shown in FIG. 1 ;

FIG. 5 is a schematic structural diagram of an embodiment of the organic light emitting display panel according to the present disclosure;

FIG. 6 is a schematic structural diagram of another embodiment of the organic light emitting display panel according to the present disclosure;

FIG. 7 is a schematic structural diagram of another embodiment of the organic light emitting display panel according to the present disclosure;

FIG. 8 is a schematic diagram of the operation timing sequence of the pixel driving circuit as shown in FIG. 2, 3 or 4 ; and

FIG. 9 is a schematic diagram of an organic light emitting display apparatus provided by the present disclosure.

The present disclosure 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 disclosure and the features in the embodiments may be combined with each other on a non-conflict basis. The present disclosure will be described below in detail with reference to the accompanying drawings and in combination with the embodiments.

Referring to FIG. 1 , a schematic structural diagram of an embodiment of a pixel driving circuit in an organic light emitting display panel according to the present disclosure is illustrated. In the present embodiment, the organic light emitting display panel includes a plurality of pixel driving circuits 100 arranged in a matrix.

As shown in FIG. 1 , the pixel driving circuit 100 includes a first scanning signal terminal Scan 1 , a second scanning signal terminal Scan 2 , a light emitting signal terminal Emit, a data signal terminal VDATA, a first initialization signal terminal VIN, a second initialization signal terminal VREF, a first voltage terminal PVDD, a second voltage terminal PVEE, a driving module 11 , an initialization module 12 , a data writing module 13 , a light emitting control module 14 and an organic light emitting diode D 1 .

The driving module 11 includes a driving transistor DT and a first capacitor C 1 . The first capacitor C 1 includes a first electrode plate 101 and a second electrode plate 102 . The first electrode plate 101 is electrically connected to the first electrode (N 2 node) of the driving transistor DT. The second electrode of the driving transistor DT is electrically connected to the first voltage terminal PVDD, and the driving transistor DT is for providing a light emitting current to the anode of the organic light emitting diode D 1 under the control of the light emitting control module 14 .

The initialization module 12 is electrically connected to the gate (N 1 node) and the first electrode (N 2 node) of the driving transistor DT, for writing signals from the first initialization signal terminal VIN and the second initialization signal terminal VREF respectively to the gate (N 1 node) of the driving transistor DT and to the first electrode (N 2 node) of the driving transistor DT, under the control of the first scanning signal terminal Scan 1 and the second scanning signal terminal Scan 2 .

The data writing module 13 is electrically connected to the second electrode plate 102 of the first capacitor C 1 , to transmit a signal of the data signal terminal VDATA to the second electrode plate 102 of the first capacitor C 1 under the control of the first scanning signal terminal Scan 1 .

The light emitting control module 14 includes a first transistor M 1 . Agate of the first transistor M 1 is electrically connected to the light emitting signal terminal Emit. A first electrode of the first transistor M 1 is electrically connected to the second electrode plate 102 of the first capacitor C 1 . A second electrode of the first transistor M 1 is electrically connected to the gate (N 1 node) of the driving transistor DT. A cathode of the organic light emitting diode D 1 is electrically connected to the second voltage terminal PVEE.

In the pixel driving circuit 100 , the initialization module 12 may first control the driving transistor DT to be turn on, and then control the potential of the gate (N 1 node) of the driving transistor DT to be stabilized as A. Charging the first electrode (N 2 node) of the driving transistor DT with the first voltage terminal PVDD, until the potential of the N 2 node is pulled up to A−Vth, the driving transistor DT is turned off and the first voltage terminal PVDD stops charging, here, Vth is the threshold voltage of the driving transistor DT. And then the N 1 node is controlled to be vacated so that the N 2 node is charged to have its potential rises to Voled by the first voltage terminal PVDD. Utilizing the coupling of the first capacitor C 1 to make the potential change of the N 3 node to be Voled−(A−Vth), where Voled is the break-over voltage of the organic light emitting diode D 1 . Assuming that the data writing module 13 writes the potential B to the N 3 node before the coupling of the first capacitor C 1 occurs, the potential of the N 3 node is B+Voled−(A−Vth). At this time, the first transistor M 1 can be controlled to be turned on, thereby stabilizing the potential of the N 1 node at the same potential B+Voled−(A−Vth) with the N 3 node. The light emitting current of the organic light emitting diode D 1 is positively correlated with Vgs−Vth, where Vgs is the potential difference between the gate (N 1 node) of the driving transistor DT and the first electrode (N 2 node) of the driving transistor DT, and the light emitting current is a value related to B+Voled−(A−Vth). As can be seen that the light emitting current is independent of the threshold voltage Vth of the driving transistor, i.e., the pixel driving circuit 100 realizes the compensation to the threshold voltage of the driving transistor and avoids the impact of the threshold drift on the display luminance.

While the first capacitor C 1 is coupled to generate an electric charge, the N 3 node is in a vacated state, so that the first capacitor C 1 is coupled at the second electrode plate 102 and generates an electric charge, changing the potential of the N 3 node and stabilizing the potential of the N 2 node at Voled, i.e., the potential of the node of the organic light emitting diode D 1 connected to the first capacitor is held stable by the first voltage terminal PVDD, so that the capacitance of the organic light emitting diode D 1 does not divide the electric charge generated by coupling and the light emitting current of the organic light emitting diode D 1 is not affected by its capacitance, and the display luminance of each organic light emitting diode does not change abnormally due to the impact of the capacitance value thereof, thereby ensuring the accuracy of the display luminance, balancing the uniformity of the display luminance and improving the display effect.

With reference to FIG. 2 , a schematic structural diagram of a specific circuit of the pixel driving circuit as shown in FIG. 1 is illustrated.

As shown in FIG. 2 , the pixel driving circuit 200 includes a driving module 21 , an initialization module 22 , a data writing module 23 and a light emitting control module 24 . Here, the driving module 21 is identical to the driving module 11 in the pixel driving circuit 100 shown in FIG. 1 . The driving module 21 includes a driving transistor DT and a first capacitor C 1 including a first electrode plate 101 and a second electrode plate 102 . A first electrode plate 101 is electrically connected to the first electrode (N 2 node) of the driving transistor DT. The second electrode of the driving transistor DT is electrically connected to the first voltage terminal PVDD, and the driving transistor DT is for providing the light emitting current to the anode of the organic light emitting diode D 1 under the control of the light emitting control module 24 . The light emitting control module 24 is identical to the light emitting control module 14 in the pixel driving circuit 100 shown in FIG. 1 , including a first transistor M 1 in which the gate of the first transistor M 1 is electrically connected to the light emitting signal terminal Emit, the first electrode of the first transistor M 1 is electrically connected to the second electrode plate 102 (N 3 node) of the first capacitor C 1 , and the second electrode of the first transistor M 1 is electrically connected to the gate (N 1 node) of the driving transistor DT.

In the present embodiment, the initialization module 22 includes a second transistor M 2 and a third transistor M 3 . The second transistor M 2 is for writing a signal of the first initialization signal terminal VIN to the gate (N 1 node) of the driving transistor DT under the control of the first scanning signal terminal Scan 1 . Specifically, a gate of the second transistor M 2 is electrically connected to the first scanning signal terminal Scan 1 . A first electrode of the second transistor M 2 is electrically connected to the first initialization signal terminal VIN. A second electrode of the second transistor M 2 is electrically connected to the gate (N 1 node) of the driving transistor DT.

The third transistor M 3 is for writing a signal of the second initialization signal terminal VREF to the first electrode (N 2 node) of the driving transistor DT under the control of the second scanning signal terminal Scan 2 . Specifically, a gate of the third transistor M 3 is electrically connected to the second scanning signal terminal Scan 2 . A first electrode of the third transistor M 3 is electrically connected to the second initialization signal terminal VREF. A second electrode of the third transistor M 3 is electrically connected to the first electrode (N 2 node) of the driving transistor DT.

The data writing module 23 includes a fourth transistor M 4 for transmitting a signal of the data signal terminal VDATA to the second electrode plate 102 of the first capacitor C 1 under the control of the first scanning signal terminal Scan 1 . Specifically, a gate of the fourth transistor M 4 is electrically connected to the first scanning signal terminal Scan 1 . A first electrode of the fourth transistor M 4 is electrically connected to the data signal terminal VDATA. A second electrode of the fourth transistor M 4 is electrically connected to the second electrode plate 102 of the first capacitor C 1 .

In the present embodiment, the first electrode (N 2 node) of the driving transistor DT is electrically connected to the anode of the organic light emitting diode D 1 . The cathode of the organic light emitting diode D 1 is electrically connected to the second voltage terminal PVEE, so that when a potential difference between the N 2 node and the second voltage terminal PVEE is higher than a break-over voltage of the organic light emitting diode D 1 , the organic light emitting diode D 1 emits light.

The pixel driving circuit 200 can compensate the threshold voltage of the driving transistor, and the problems of threshold drift impacting the display luminance and a poor display uniformity caused by different capacitances of different organic light emitting diodes can be avoided. The pixel driving circuit 200 has the following advantages: simple circuit structure, containing only one capacitor, each pixel driving circuit occupying a very small area, facilitating the design of a high-resolution display panel.

With further reference to FIG. 3 , a schematic structural diagram of another specific circuit of the pixel driving circuit as shown in FIG. 1 is illustrated.

As shown in FIG. 3 , the pixel driving circuit 300 includes a light emitting control module 34 , and a driving module 21 , an initialization module 22 , a data writing module 23 which are identical to those in the pixel driving circuit 200 shown in FIG. 2 . Here, the light emitting control module 34 includes the light emitting control module 24 shown in FIG. 2 and further includes a fifth transistor M 5 . The fifth transistor M 5 is for transmitting a potential signal of the first electrode (N 2 node) of the driving transistor DT to the anode of the organic light emitting diode D 1 under the control of the light emitting signal terminal Emit. Specifically, a gate of the fifth transistor M 5 is electrically connected to the light emitting signal terminal Emit. A first electrode of the fifth transistor M 5 is electrically connected to the first electrode (N 2 node) of the driving transistor DT. A second electrode of the fifth transistor M 5 is electrically connected to the anode of the organic light emitting diode D 1 . The second electrode of the organic light emitting diode D 1 is electrically connected to the second voltage terminal PVEE.

In the present embodiment, the anode of the organic light emitting diode D 1 is not directly electrically connected to the first electrode (N 2 node) of the driving transistor DT, but through the fifth transistor M 5 . The pixel driving circuits 200 and 300 first need to initialize the potentials of the gate (N 1 node) and the first electrode (N 2 node) of the driving transistor DT, acquire the threshold voltage Vth of the driving transistor DT, then write data signal to the driving transistor DT, and at last control the organic light emitting diode D 1 to emit light according to the voltage difference between the gate and the first electrode of the driving transistor DT. Accordingly, for the pixel driving circuit 200 shown in FIG. 2 , in the potential process of initializing the N 1 node and the N 2 node, the process of capturing the threshold voltage of the driving transistor DT, or the process of writing the data signal, if the voltage difference between the N 2 node and the second voltage terminal PVEE is greater than the break-over voltage of the organic light emitting diode D 1 , the organic light emitting diode emits light, but then the emission luminance of the organic light emitting diode is not accurate, thus may causing a display error. And when the pixel driving circuit 300 is used, in the potential process of initializing the N 1 node and the N 2 node, the process of capturing the threshold voltage of the driving transistor DT, or the process of writing the data signal, the light emitting signal terminal Emit may be used to control the fifth transistor M 5 to be turned off, to ensure that the signal of the N 2 node can not be transmitted to the organic light emitting diode during the initialization, threshold voltage capturing, and the data signal writing processes, i.e., the organic light emitting diode D 1 is not allowed to be turned on. After the data signal is written and the circuit operation state is stable, the fifth transistor M 5 can be controlled to be turned on, and then the organic light emitting diode D 1 may emit light according to the written data signal, thereby the display luminance of the organic light emitting diode D 1 can be ensured to be accurate.

With further reference to FIG. 4 , a schematic structural diagram of another specific circuit of the pixel driving circuit as shown in FIG. 1 is illustrated.

As shown in FIG. 4 , the pixel driving circuit 400 includes an initialization module 42 , and a driving module 21 , a data writing module 23 , a light emitting control module 34 which are identical to those in the pixel driving circuit 300 shown in FIG. 3 . Here, the initialization module 42 includes an initialization module 22 of the pixel driving circuit 300 shown in FIG. 3 and further includes a sixth transistor M 6 . The sixth transistor M 6 is for transmitting the signal of the second initialization signal terminal VREF to the anode (N 4 node) of the organic light emitting diode D 1 under the control of the second scanning signal terminal Scan 2 . Specifically, a gate of the sixth transistor M 6 is electrically connected to the second scanning signal terminal Scan 2 . A first electrode of the sixth transistor M 6 is electrically connected to the second initialization signal terminal VREF. The second electrode of the sixth transistor M 6 is electrically connected to the anode (N 4 ) of the organic light emitting diode D 1 .

Similar to the pixel driving circuit shown in FIG. 3 , the pixel driving circuit 400 of the present embodiment has the advantages that the threshold voltage of the driving transistor can be compensated, the luminance of the organic light emitting diode is not related to its capacitance value, and the occupied area is small and the like. It is also possible to ensure that the organic light emitting diodes do not emit light at the phases of node potential initialization, threshold voltage capturing, data writing, etc. to ensure the accuracy of the display luminance. On the basis of the pixel driving circuit 300 shown in FIG. 3 , the pixel driving circuit 400 of the present embodiment adds a sixth transistor M 6 for resetting the anode of the organic light emitting diode D 1 . With the sixth transistor M 6 , the organic light emitting diode D 1 may be quickly reset to a nonluminous state before displaying a frame, and the emission luminance of the organic light emitting diode in the previous frame can be prevented from affecting the state of the organic light emitting diode in the currently displayed frame, which further enhances the display accuracy.

The present disclosure provides an organic light emitting display panel including the above-described pixel driving circuits, the organic light emitting display panel including pixel driving circuits arranged in an array.

With reference to FIG. 5 , a schematic structural diagram of an embodiment of the organic light emitting display panel according to the present disclosure is illustrated.

As shown in FIG. 5 , the organic light emitting display panel 500 may include pixel driving circuits 51 arranged in an array. The pixel driving circuit 51 may be any one of the pixel driving circuits shown in the above FIGS. 1 to 4 .

The organic light emitting display panel 500 further includes a plurality of first scanning signal lines S 11 , S 12 , S 13 , S 1 (m−1), S 1 m , a plurality of second scanning signal lines S 21 , S 22 , S 23 , S 2 (n−1), S 2 m , a plurality of light emitting signal lines E 1 , E 2 , E 3 , E (n−1), Em, a plurality of data signal lines DATA 11 , DATA 21 , DATA 12 , DATA 22 , DATA 13 , DATA 23 , . . . , DATA 1 (n−2), DATA 2 (n−2), DATA 1 (n−2), DATA 2 (n−2), DATA 1 n , DATA 2 n , at least one first initialization signal line INI 1 , INI 2 , INI 3 , . . . , INI (n−2), INI (n−1), INIn, at least one second initialization signal line REF 1 , REF 2 , REF 3 , . . . , REF (n−2), REF (n−1), REFn, a first voltage signal line VDD and a second voltage signal line VEE, here, m and n are positive integers.

The first scanning signal terminal Scan 1 of each pixel driving circuit 51 is electrically connected to a first scanning signal line S 11 , S 12 , S 13 , S 1 (m−1) or S 1 m . The second scanning signal terminal Scan 2 of each pixel driving circuit 51 is electrically connected to a second scanning signal line S 21 , S 22 , S 23 , S 2 (m−1) or S 2 m . The light emitting signal terminal Emit of each pixel driving circuit 51 is electrically connected to a light emitting signal line E 1 , E 2 , E 3 , E (m−1) or Em. The data signal terminal VDATA of each pixel driving circuit 51 is electrically connected to a data signal line DATA 11 , DATA 21 , DATA 12 , DATA 22 , DATA 13 , DATA 1 DATA 2 (n−2), DATA 1 (n−1), DATA 2 (n−1), DATA 1 n or DATA 2 n . The first initialization signal terminal VIN of each pixel driving circuit 51 is electrically connected to a first initialization signal line INI 1 , INI 2 , INI 3 , . . . , INI (n−2), INI (n−1) or INIn. The second initialization signal terminal VREF of each pixel driving circuit 51 is electrically connected to a second initialization signal line REF 1 , REF 2 , REF 3 , . . . , REF (n−2), REF(n−1) or REFn. The first voltage terminal PVDD of each pixel driving circuit 51 is electrically connected to a first voltage signal line VDD. The second voltage terminal PVEE of each pixel driving circuit 51 is electrically connected to a second voltage signal line VEE.

In the present embodiment, the data signal terminals in the plurality of pixel driving circuits 51 located in the same column are connected to two data signal lines, each of which is connected to a plurality of pixel driving circuits such as a plurality of pixel driving circuits 51 located in the first column are electrically connected to the data lines DATA 11 and DATA 21 . Usually, luminance intensities of various sub-pixels are different, emission luminances of various organic light emitting diodes are different, and data signals received by the pixel driving circuits are different. When a plurality of pixel driving circuits are connected to one data signal line, the data signal line needs to transmit different data signals to the different pixel driving circuits in divided times, that is, during the time of displaying a frame picture, the driver IC (integrated circuit) needs to control the signal transmitted by each data signal line to change several times. The more the number of data signal lines, the less the number of pixel driving circuits that each data line needs to drive, so that the number of changes in the signal transmitted by each data signal line is reduced, and the rate of change of the signal transmitted from the driver IC to each data line is reduced, and the load of the driver IC can be reduced.

Further, as shown in FIG. 5 , each of the first scanning signal lines S 11 , S 12 , S 13 , S 1 (m−1) or S 1 m is respectively electrically connected to the first scanning signal terminal Scan 1 of a row of pixel driving circuits 51 . Each of the second scanning signal lines S 21 , S 22 , S 23 , S 2 (m−1) or S 2 m is respectively electrically connected to the second scanning signal terminal Scan 2 of a row of pixel driving circuits 51 . Each of the light emitting signal lines E 1 , E 2 , E 3 , E (m−1) or Em is respectively electrically connected to the light emitting signal terminal Emit of a row of pixel driving circuits 51 . Each of the first initialization signal lines INI 1 , INI 2 , INI 3 , . . . , INI (n−2), INI (n−1) or INIn is respectively electrically connected to the first initialization signal terminal VIN of a column of pixel driving circuits. Each of the second initialization signal lines REF 1 , REF 2 , REF 3 , . . . , REF (n−2), REF (n−1) or REFn is respectively electrically connected to the second initialization signal terminal VREF of a column of pixel driving circuits. The first voltage terminal PVDD of each pixel driving circuit 51 is electrically connected to the first voltage signal line VDD, and the second voltage terminal PVEE of each pixel driving circuit 51 is electrically connected to the second voltage signal line VEE. When displaying, the pixel driving circuits located on the same row are operated at the same time, so that the organic light emitting diodes in the pixel driving circuits located in the same row emit light simultaneously, and the organic light emitting diodes in the pixel driving circuit array may be lit line by line to complete the display of the entire screen.

With reference to FIG. 6 , a schematic structural diagram of another embodiment of the organic light emitting display panel according to the present disclosure is illustrated.

Unlike the embodiment shown in FIG. 5 , the organic light emitting display panel 600 in the present embodiment includes a plurality of data signal lines DATA 1 , DATA 2 , DATA 3 , . . . , DATA (n−2), DATA (n−1) and DATAn. Here, n is a positive integer. Each data signal line is respectively electrically connected to the data signal terminal of a column of pixel driving circuits 61 . In the present embodiment, the pixel driving circuits 61 located in the same column are connected to the same data signal line. Compared with the embodiment shown in FIG. 5 , the organic light emitting display panel 600 shown in FIG. 6 reduces the number of data signal lines. Usually the data signal line can be directly connected to the port of the driver IC or connected to the port of the driver IC through the time-sharing circuit, and the number of ports of the driver IC required and occupied by the data signal line is positively correlated with the number of the data signal lines. Therefore, the organic light emitting display panel of the present embodiment can reduce the number of the ports of the driver IC occupied and simplify the port design of the IC.

With further reference to FIG. 7 , a schematic structural diagram of another embodiment of the organic light emitting display panel according to the present disclosure is illustrated.

On the basis of the organic light emitting display panel 600 shown in FIG. 6 , the first initialization signal terminal VIN of each pixel driving circuit 71 in the organic light emitting display panel 700 provided in the present embodiment is electrically connected to the same first initialization signal line INI. The second initialization signal terminal VREF of each pixel driving circuit 71 is electrically connected to the same second initialization signal line REF. That is, each pixel driving circuit 71 receives the first initialization signal through the same first initialization signal line INI, and each pixel driving circuit 71 receives the second initialization signal through the same second initialization signal line REF, thereby further reducing the number of signal lines connected to the driver IC and reducing the number of ports occupied by the driver IC.

FIGS. 5, 6, and 7 only schematically show the connection relationship between signal lines and the pixel driving circuits in the organic light emitting display panel of the present disclosure. In other embodiments of the present disclosure, the plurality of pixel driving circuits connected to each data signal line may be located in different columns. The plurality of pixel driving circuits connected to each first scanning signal line may be located in different rows. The pixel driving circuits connected to each second scanning signal line may be located in different rows. The plurality of pixel driving circuits connected to each light emitting signal line may be located in different rows. The number of the first voltage signal lines and the second voltage signal lines may be plural.

It should be noted that the first transistor M 1 , the second transistor M 2 , the third transistor M 3 , the fourth transistor M 4 , the fifth transistor M 5 , and the driving transistor DT in the above embodiments may each be a N-type transistor or a P-type transistor. When the driving transistor DT is a N-type transistor, its threshold voltage Vth>0. When the driving transistor is a P-type transistor, its threshold voltage Vth<0.

The present disclosure also provides a driving method applied to each of the embodiments of the above organic light emitting display panel. In the driving method, the operation process of each pixel driving circuit includes three phases.

Specifically, in the first phase, a first level signal is provided to the first scanning signal terminal Scan 1 and the second scanning signal terminal Scan 2 , a second level signal is provided to the light emitting signal terminal Emit, a first initialization signal Vin is provided to the first initialization signal terminal VIN, a second initialization signal VRef 1 is provided to the second initialization signal terminal VREF, and a data signal Vdata is provided to the data signal terminal. The initialization module writes the first initialization signal Vin and the second initialization signal VRef 1 respectively to the gate (N 1 node) of the driving transistor DT and the first electrode (N 2 node) of the driving transistor DT, and the data writing module transmits the data signal Vdata to the second electrode plate 102 of the first capacitor C 1 .

In the second phase, the first level signal is provided to the first scanning signal terminal Scan 1 , the second level signal is provided to the second scanning signal terminal Scan 2 and the light emitting signal terminal Emit, the first initialization signal Vin is provided to the first initialization signal terminal VIN, and the data signal Vdata is provided to the data signal terminal VDATA. The initialization module writes the first initialization signal Vin to the gate (N 1 node) of the driving transistor DT. The data writing module transmits the data signal Vdata to the second electrode plate 102 of the first capacitor C 1 . The driving transistor DT is turned on. The first electrode plate 101 of the first capacitor C 1 is charged by the first voltage terminal PVDD.

In the third phase, the second level signal is provided to the first scanning signal terminal Scan 1 and the second scanning signal terminal Scan 2 , and the first level signal is provided to the light emitting signal terminal Emit. The driving transistor DT and the first transistor M 1 are turned on. The first electrode (N 2 node) of the driving transistor DT is charged by the first voltage terminal PVDD. The light emitting control module turns on the second electrode plate 102 (N 3 node) of the first capacitor C 1 and the gate (N 1 node) of the driving transistor DT. The potential of the gate (N 1 node) of the driving transistor DT rises under the coupling of the first capacitor C 1 . The organic light emitting diode D 1 emits light under the voltage difference between the gate (N 1 node) and the first electrode (N 2 node) of the driving transistor DT.

Here, the voltage value of the first initialization signal Vin is greater than the sum of the voltage value of the second initialization signal VRef 1 and the threshold voltage of the driving transistor DT.

The operation principle of each pixel driving circuit driven by the driving method will be further illustrated with reference to FIG. 8 in the following example, in which the first transistor M 1 , the second transistor M 2 , the third transistor M 3 , the fourth transistor M 4 , the fifth transistor M 5 , the sixth transistor M 6 and the driving transistor DT in the above embodiments are all N-type transistors, the first level signal in the driving method is a high level signal, and the second level signal is a low level signal. Here, SC 1 , SC 2 , EM, Data, IN and Vref denote to signals provided respectively to the first scanning signal terminal Scan 1 , the second scanning signal terminal Scan 2 , the light emitting signal terminal Emit, the data signal terminal VDATA, the first initialization signal terminal VIN and the second initialization signal terminal VREF. Here, the high level and the low level represent only the relative relationship between the levels, and are not particularly limited to a certain level signal. The high level signal may be a signal for turning on the first to the sixth transistors, and the low level signal may be a signal for turning off the first to the sixth transistors.

With reference to FIG. 8 , a schematic diagram of the operation timing sequence of the pixel driving circuits as shown in FIGS. 2, 3 and 4 is illustrated.

For the pixel driving circuit 200 shown in FIG. 2 , in the first phase T 1 , a first level signal is provided to the first scanning signal terminal Scan 1 and the second scanning signal terminal Scan 2 . A second level signal is provided to the light emitting signal terminal Emit. The first initialization signal Vin is provided to the first initialization signal terminal VIN. The second initialization signal VRef 1 is provided to the second initialization signal terminal VREF. The data signal Vdata is provided to the data signal terminal. The second transistor M 2 is turned on, and the first initialization signal Vin is written to the gate (N 1 node) of the driving transistor DT. The third transistor M 3 is turned on, and the second initialization signal VRef 1 is written to the first electrode (N 2 node) of the driving transistor DT. The fourth transistor M 4 is turned on, and the data signal Vdata is transmitted to the second electrode plate 102 of the first capacitor C 1 . Here, the voltage value of the first initialization signal Vin is greater than the sum of the voltage value of the second initialization signal VRef 1 and the threshold voltage Vth of the driving transistor DT, and the voltage difference between the second initialization signal VRef 1 and the second voltage terminal PVEE (the voltage value is VPVEE) is less than the break-over voltage Voled of the organic light emitting diode D 1 . That is, Vin−VRef 1 >Vth and VRef 1 −VPVEE<Voled, and the voltage difference between the gate and the first electrode of the driving transistor DT is greater than its threshold voltage, so that the driving transistor DT is turned on before entering the next phase. In addition, the voltage difference between the anode and the cathode of the organic light emitting diode D 1 is less than its break-over voltage thereof, ensuring that the organic light emitting diode D 1 is prevented from being lit at this phase.

In the second phase T 2 , the first level signal is provided to the first scanning signal terminal Scan 1 . The second level signal is provided to the second scanning signal terminal Scan 2 and the light emitting signal terminal Emit. The first initialization signal Vin is provided to the first initialization signal terminal VIN. The data signal Vdata is provided to the data signal terminal VDATA. At this time, the third transistor M 3 is turned off and the second transistor M 2 is turned on, so that the potential of the gate (N 1 node) of the driving transistor DT is maintained as the first initialization signal Vin, and the potential of the N 1 node VN 1 =Vin. The fourth transistor M 4 is turned on, so that the potential of the second electrode plate 102 (N 3 node) of the first capacitor C 1 is maintained as the data signal Vdata, and the potential of the N 3 node VN 3 =Vdata. The driving transistor DT is turned on and the second electrode (or the first electrode plate 101 of the first capacitor C 1 , the N 2 node) of the driving transistor DT is charged by the first voltage terminal PVDD. When the potential of the N 2 node rises to Vin−Vth, the voltage difference between the gate and the first electrode of the driving transistor DT is equal to Vth, the driving transistor is turned off, and the first voltage terminal PVDD stops charging the N 2 node. At this phase, the potential VN 2 of the N 2 node is stabilized at VN 2 =Vin−Vth, here Vth is the threshold voltage of the driving transistor DT. Here, the N 2 node is electrically connected to the anode of the organic light emitting diode D 1 and needs to meet the following requirements: the voltage difference between the first initialization signal Vin and the second voltage terminal PVEE is less than the sum of the threshold voltage Vth of the driving transistor DT and the break-over voltage Voled of the organic light emitting diode D 1 , that is, Vin VPVEE<Vth+Voled, or Vin−Vth−VPVEE<Voled, so that the voltage difference between the anode and the cathode of the organic light emitting diode D 1 is less than its break-over voltage to ensure that the organic light emitting diode does not emit light at the second phase T 2 .

In the third phase T 3 , the second level signal is provided to the first scanning signal terminal Scan 1 and the second scanning signal terminal Scan 2 , and the first level signal is provided to the light emitting signal terminal Emit. When the gate (N 1 node) of the driving transistor DT is in a vacated state and the potential thereof is unstable, the first electrode (N 2 node) of the driving transistor DT may continue charged by the first voltage terminal PVDD, and when the potential of the N 2 node rises to the break-over voltage Voled of the organic light emitting diode D 1 , the organic light emitting diode D 1 emits light, and the potential of the N 2 node stops rising, at this point VN 2 =Voled. The second electrode plate 102 (N 3 node) of the first capacitor C 1 is in a vacated state at the third phase T 3 , so that the potential of the N 3 node also changes under the coupling of the first capacitor C 1 , and the change is consistent with the potential change of the N 2 node, both of which are Voled−(Vin−Vth). Then the potential of the N 3 node VN 3 =Vdata+Voled−(Vin−Vth), and the first transistor M 1 is turned on, so that the potential of the N 1 node VN 1 =VN 3 =Vdata+Voled−(Vin−Vth).

In the third phase T 3 , the organic light emitting diode D 1 emits light according to the voltage difference Vgs between the gate (N 1 node) of the driving transistor DT and the first electrode (N 2 node) of the driving transistor DT. At this time, the source of the driving transistor DT is the N 2 node, and the gate source potential difference of the driving transistor DT is Vgs=VN 1 −VN 2 =Vdata+Voled−(Vin−Vth)−Voeld=Vdata−Vin+Vth, and the light emitting current Ids of the organic light emitting diode D 1 can be calculated using the following equation

Here, K is the ratio of the width and the length of the channel of the driving transistor DT and a related coefficient of capacitance per unit area of the driving transistor DT. As can be observed from the equation (1), the light emitting current Ids of the organic light emitting device D 1 is independent of the threshold voltage Vth of the driving transistor DT, the capacitance value of the first capacitor C 1 and the capacitance value of the organic light emitting diode D 1 , thereby the pixel driving circuit 200 shown in FIG. 2 realizes the compensation to the threshold voltage of the driving transistor. In addition, different organic light emitting diodes have the same light emitting current under the driving of the same data signal Vdata, so as to have the same emission luminance, resulting improvements of the luminance uniformity of the display and the display effect.

The pixel driving circuit 300 shown in FIG. 3 differs from the operation principle of the pixel driving circuit 200 shown in FIG. 2 described above in that: the N 2 node is connected to the anode of the organic light emitting diode D 1 through the fifth transistor M 5 , so that in the first phase T 1 and the second phase T 2 , the fifth transistor M 5 is turned off, the N 2 node is disconnected from the organic light emitting diode D 1 , and the potential of the N 2 node does not affect the state of the organic light emitting diode. Therefore, for the pixel driving circuit shown in FIG. 3 , it is only required that the voltage value of the first initialization signal Vin is greater than the sum of the voltage value of the second initialization signal VRef 1 and the threshold voltage Vth of the driving transistor DT (i.e., Vin−VRef 1 >Vth), which ensures that in the first phase T 1 the driving transistor DT is turned on. It is not necessary to satisfy that the voltage difference between the second initialization signal VRef 1 and the second voltage terminal PVEE (voltage value is VPVEE) is less than the break-over voltage Voled of the organic light emitting diode D 1 (i.e., VRef 1 −VPVEE<Voled), and that the voltage difference between the first initialization signal Vin and the second voltage terminal PVEE is less than the sum of the threshold voltage Vth of the driving transistor DT and the break-over voltage Voled of the organic light emitting diode D 1 (i.e., Vin−Vth−VPVEE<Voled). Thus, the limitation to the first initialization signal Vin and the second initialization signal VRef 1 is reduced, so that the driver IC may set an appropriate first initialization signal value and second initialization signal value within an optional range, and the load of the driver IC can be reduced.

The pixel driving circuit 400 shown in FIG. 4 differs from the operation principle of the above described pixel driving circuit 200 shown in FIG. 2 in that: in the first phase T 1 , the fifth transistor M 5 is turned off, the sixth transistor M 6 is turned on, and the second initialization signal VRef 1 is transmitted to the anode (N 4 node) of the organic light emitting diode D 1 . Similar to the pixel driving circuit 200 shown in FIG. 2 , the pixel driving circuit 400 also need to meet the following conditions: the voltage value of the first initialization signal Vin is greater than the sum of the voltage value of the second initialization signal VRef 1 and the threshold voltage Vth of the driving transistor DT (i.e., Vin−VRef 1 >Vth). In addition, since the potential of the anode of the organic light emitting diode D 1 is also initialized to VRef 1 , it is also required that the voltage difference between the second initialization signal VRef 1 and the second voltage terminal PVEE (voltage value is VPVEE) is less than the break-over voltage Voled of the organic light emitting diode D 1 (i.e., VRef 1 −VPVEE<Voled), to ensure that the organic light emitting diode D 1 does not emit light in the first phase T 1 . In the second phase T 2 , the fifth transistor M 5 and the sixth transistor M 6 in the pixel driving circuit 300 are turned off, so that the potential of the N 2 node does not affect whether the organic light emitting diode D 1 is turned on, and for the pixel driving circuit 400 shown in FIG. 4 , it is not necessary to satisfy that the voltage difference between the first initialization signal Vin and the second voltage PVEE is less than the sum of the threshold voltage Vth of the driving transistor DT and the break-over voltage Voled of the organic light emitting diode D 1 (i.e., Vin−Vth−VPVEE<Voled), it can be ensured that the organic light emitting diode D 1 does not emit light in the second phase T 2 .

For the pixel driving circuit 300 shown in FIG. 3 and the pixel driving circuit 400 shown in FIG. 4 , the driving method further includes: in the third phase T 3 , the fifth transistor M 5 is turned on so that the light emitting current provided by the driving transistor DT is transmitted to the organic light emitting Diode D 1 . Similarly, the light emitting current of the organic light emitting diode D 1 is only related to the data signal Vdata and the first initialization signal Vin, and is independent of the threshold voltage Vth of the driving transistor DT and the capacitance of the organic light emitting diode D 1 , so that the pixel driving circuits can be kept in a stable and reliable working status, which helps to enhance the display effect. In addition, as can be seen from FIG. 8 , each of the pixel driving circuits described above has a relatively simple the operation timing sequence, which helps to reduce the load of the driver IC.

Alternatively, the driving method further comprises: providing the first voltage signal to the first voltage terminal PVDD and providing the second voltage signal to the second voltage terminal PVEE in the first phase T 1 , the second phase T 2 and the third phase T 3 . The voltage value of the first voltage signal is higher than the voltage value of the second voltage signal.

In addition, the present disclosure also provides an organic light emitting display apparatus, as shown in FIG. 9 , the organic light emitting display apparatus 900 includes the organic light emitting display panel of each of the embodiments described above, and may be a mobile phone, a tablet computer, a wearable device, or the like. It is understandable that the organic light emitting display apparatus 900 may include a known structure such as a package film and a protective glass, therefore detailed descriptions will be omitted.

The foregoing is only a description of the preferred embodiments of the present disclosure and the applied technical principles. It should be appreciated by those skilled in the art that the inventive scope of the present disclosure is not limited to the technical solutions formed by the particular combinations of the above technical features. The inventive scope should also cover other technical solutions formed by any combinations of the above technical features or equivalent features thereof without departing from the concept of the invention, such as, technical solutions formed by replacing the features as disclosed in the present disclosure with (but not limited to), technical features with similar functions.