Organic light-emitting diode display unit, driving method thereof and display device

An organic light-emitting diode display unit, a driving method thereof and a display device are disclosed. At least part of pixel units are pixel units each with a stacked structure; each pixel unit with the stacked structure includes two adjacent subpixel unit stacked groups; and each subpixel unit stacked group includes at least two subpixel units which have different emitting colors and are stacked and insulated from each other. During display of different image frames, each subpixel unit stacked group in each pixel unit with the stacked structure can display gray-scale effect of at least two colors based on applied signals. Compared with an approach that each subpixel unit can only display gray-scale effect of only one color for different image frames, the display effect can be improved.

The application is a U.S. National Phase Entry of International Application No. PCT/CN2015/070894 filed on Jan. 16, 2015, designating the United States of America and claiming priority to Chinese Patent Application No. 201410515749.X, filed on Sep. 29, 2014. The present application claims priority to and the benefit of the above-identified applications and the above-identified applications are incorporated by reference herein in their entirety.

TECHNICAL FIELD

At least one embodiment of the present disclosure relates to an organic light-emitting diode (OLED) display unit, a driving method thereof and a display device.

BACKGROUND

An OLED display unit is one of hotspots in the current research field of flat-panel display devices. Compared with liquid crystal display (LCD) devices, the OLED display unit has the advantages of low energy consumption, a low production cost, self-luminescence, a wide viewing angle, and a rapid response speed, etc. Currently, the OLED display unit has begun to replace the LCD devices in the flat-panel display field such as mobile phones, personal digital assistants (PDAs) and digital cameras.

The OLED display unit mainly includes: a base substrate and pixel units formed on the base substrate and arranged in a matrix. The pixel unit includes a plurality of subpixel units arranged in the same layer and pixel circuits which are respectively connected with the subpixel units in one-to-one correspondence. One subpixel unit includes an OLED structure.

SUMMARY

Embodiments of the present disclosure provide an OLED display unit, a driving method thereof and a display device, which are used for improving the pixel display effect of the OLED display unit.

At least one embodiment of the present disclosure provides an OLED display unit. The OLED display unit includes a base substrate and a plurality of pixel units disposed on the base substrate. The plurality of pixel units includes a plurality of subpixel units and pixel circuits which are respectively connected with the subpixel units in one-to-one correspondence. The subpixel units are OLED structures, and pixel circuits in a same pixel unit are respectively connected with different data signal lines. At least part of the pixel units are pixel units each with a stacked structure, where each of the pixel units with the stacked structure includes two adjacent subpixel unit stacked groups. Each subpixel unit stacked group includes at least two subpixel units which have different emitting colors and are stacked and insulated from each other, and a quantity of subpixel units in each subpixel unit stacked group of a same pixel unit with the stacked structure is identical. In each pixel unit with the stacked structure, two subpixel units disposed in a same layer form a subpixel unit layer; and in a same pixel unit with the stacked structure, only one subpixel unit layer includes two subpixel units that have same emitting colors, and other subpixel unit layers each include two subpixel units that have different emitting colors.

At least one embodiment of the present disclosure further provides a method for driving the OLED display unit. The method comprises: receiving video signals of images; and controlling, based on corresponding colors of an image at corresponding positions of the pixel units in the OLED display unit, subpixel units that display light of the corresponding colors and that are in the pixel units at the corresponding positions to display, where the image corresponds to a video signal of a current image frame.

The OLED display unit further includes: all of the pixel units with the stacked structure are regularly arranged; in each pixel unit with the stacked structure, two subpixel unit stacked groups are adjacent to each other along a row direction; arrangement positions of odd rows of pixel units with the stacked structure correspond to each other, and arrangement positions of even rows of pixel units with the stacked structure correspond to each other; and in two adjacent rows of pixel units with the stacked structure, two subpixel unit stacked groups which are adjacent to each other in position and have a same structure are misaligned. At least one embodiment of the present disclosure further provides a method for driving the OLED display unit, which includes: during display of an odd image frame, controlling one subpixel unit layer in each odd row of pixel units with the stacked structure to emit light, and during display of an even image frame, controlling another subpixel unit layer in each odd row of pixel units with the stacked structure to emit light; and during display of the odd image frame, controlling one subpixel unit layer in each even row of pixel units with the stacked structure to emit light, and during display of the even image frame, controlling another subpixel unit layer in each even row of pixel units with the stacked structure to emit light. Furthermore, during display of each image frame, subpixel units which emit light and are in the odd rows of pixel units with the stacked structure and subpixel units which emit light and are in the even rows of pixel units with the stacked structure are in different layers.

The OLED display unit further includes: all of the pixel units with the stacked structure are regularly arranged; in each pixel unit with the stacked structure, two subpixel unit stacked groups are adjacent to each other along the column direction; arrangement positions of odd columns of pixel units with the stacked structure correspond to each other, and arrangement positions of even columns of pixel units with the stacked structure correspond to each other; and in two adjacent columns of pixel units with the stacked structure, two subpixel unit stacked groups which are adjacent to each other in position and have a same structure are misaligned. At least one embodiment of the present disclosure further provides a method for driving the OLED display unit, which includes: during display of an odd image frame, controlling one subpixel unit layer in each odd column of pixel units with the stacked structure to emit light, and during display of an even image frame, controlling another subpixel unit layer in each odd column of pixel units with the stacked structure to emit light; and during display of the odd image frame, controlling one subpixel unit layer in each even column of pixel units with the stacked structure to emit light, and during display of the even image frame, controlling another subpixel unit layer in each even column of pixel units with the stacked structure to emit light. Furthermore, during display of each image frame, subpixel units which emit light and are in the odd columns of pixel units with the stacked structure and subpixel units which emit light and are in the even columns of pixel units with the stacked structure are in different layers.

At least one embodiment of the present disclosure further provides a display device, which includes the OLED display unit provided by the embodiments of the present disclosure.

DETAILED DESCRIPTION

For more clear understanding of the objectives, technical proposals and advantages of the embodiments of the present disclosure, clear and complete description will be given below to the technical proposals of the embodiments of the present disclosure with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the preferred embodiments are only partial embodiments of the present disclosure but not all the embodiments. All the other embodiments obtained by those skilled in the art without creative efforts on the basis of the embodiments of the present disclosure illustrated shall fall within the scope of protection of the present disclosure.

The shapes and sizes of layers in the accompanying drawings do not reflect the actual scale of the OLED display unit and only reflect a partial structure of the OLED display unit. The purpose is only to illustrate the content of the present disclosure.

FIG. 1is a schematic structural view of an OLED structure. As illustrated inFIG. 1, the OLED structure1generally includes an anode01and a cathode02arranged opposite to each other, and a light emission layer03disposed between the anode01and the cathode02. The emission of light by the OLED display unit is achieved by the following means: a pixel circuit2applies a voltage between the anode01and the cathode02; holes in the anode01and electrons in the cathode02are recombined in the light emission layer03to produce excitons; the excitons are migrated under the action of electric fields, to transfer energy to luminescent molecules in the light emission layer03and excite electrons in the luminescent molecules for the transition from the ground state to the excited state; and energy of the excited state is subjected to radiative transition to produces photons.

Different from the case that an LCD utilizes a stable voltage to control the brightness, the OLED is driven by a current and needs a stable current to control light emission. Due to technological process, device aging and other reasons, a threshold voltage Vthof a driving transistor in a 2T1C (two thin-film transistors (TFTs) or metal-oxide-semiconductor (MOS) tubes and a capacitor) pixel circuit has unevenness, so that the current flowing through the OLED of each pixel can be changed, and hence the display brightness can be uneven. Therefore, the display effect of the entire image can be affected, and hence the brightness of different areas of the OLED display unit can be uneven.

Currently, in order to compensate the unevenness of the threshold voltage of the driving transistor in the pixel circuit, the number of TFTs and the number of capacitors in the pixel circuit are increased, and the threshold voltage drift of the driving transistor in the pixel circuit is compensated by the mutual cooperation of the TFTs and the capacitors. However, due to the increased number of the TFTs and the increased number of the capacitors in the pixel circuit, a reduction of the pixel size can be greatly limited, and hence the pixel display effect can be affected.

Therefore, in the case with a large amount of TFTs in the pixel circuit of the current OLED display unit, how to improve the pixel display effect has become the focus of attention of various manufacturers.

At least one embodiment of the present disclosure provides an OLED display unit, which, as illustrated inFIG. 2, comprises a base substrate10and a plurality of pixel units11disposed on the base substrate10. Each pixel unit11includes a plurality of subpixel units111and pixel circuits112which are respectively connected with the subpixel units111in one-to-one correspondence. The subpixel units111have OLED structures, and the pixel circuits112in the same pixel unit11are respectively connected with different data lines. At least a part of the pixel units11are pixel units11each with a stacked structure, and each pixel unit11with the stacked structure includes two adjacent subpixel unit stacked groups110. Each subpixel unit stacked group110includes at least two subpixel units111which have different emitting colors and are stacked and insulated from each other, and the number of the subpixel units111of each subpixel unit stacked group110in the same pixel unit11with the stacked structure is the same. In the pixel unit11with the stacked structure, two subpixel units111disposed in the same layer are taken as a subpixel unit layer. In a same pixel unit11with the stacked structure, only one subpixel unit layer includes two subpixel units111having the same emitting color, and one or more other subpixel unit layers each include two subpixel units111having different emitting colors.

In the OLED display unit provided by the embodiments of the present disclosure, at least part of the pixel units are pixel units with a stacked structure, and each pixel unit with the stacked structure includes two adjacent subpixel unit stacked groups; each subpixel unit stacked group includes at least two subpixel units which have different emitting colors and are stacked and insulated from each other; and the number of the subpixel units of each subpixel unit stacked group in the same pixel unit with the stacked structure is the same. Therefore, during display of different image frames, each subpixel unit stacked group in each pixel unit with the stacked structure can display the gray-scale effect of at least two colors according to applied signals. Compared with the case that each subpixel unit can only display the gray-scale effect of one color for different image frames, the OLED display unit can improve the display effect because each subpixel unit stacked group can display more colors.

In addition, for a same pixel unit with the stacked structure from the pixel units with the stacked structure, only one subpixel unit layer includes two corresponding subpixel units that have the same emitting color, and the other subpixel unit layer includes two corresponding subpixel units that have different emitting colors. Therefore, a virtual display pixel arrangement effect can also be achieved by controlling emission of light of the subpixel units in different layers during display.

In at least one embodiment, in order to be able to independently control the subpixel units in the same pixel unit with the stacked structure, in the OLED display unit provided by the embodiments of the present disclosure as illustrated inFIG. 3, the subpixel units111in the same pixel unit11with the stacked structure are respectively connected with corresponding pixel circuits112through corresponding selector switches113. The selector switches113are configured to respectively receive corresponding control signals which are used for controlling the switching on or off of the selector switches113.

For instance, as illustrated inFIG. 3, one pixel unit11with the stacked structure includes four subpixel units111. A first subpixel unit for emitting red light (R-OLED) is connected with a first pixel circuit112through a selector switch113; the first pixel circuit112is connected with a corresponding data line (represented as “data” inFIG. 3); a corresponding control signal G1controls to switch on or off of the selector switch113. A second subpixel unit for emitting red light (R-OLED) is connected with a second pixel circuit112through a selector switch113; the second pixel circuit112is connected with a corresponding data line; a corresponding control signal G2controls to switch on or off of the selector switch113. An OLED structure for emitting green light (G-OLED) is connected with a third pixel circuit112through a selector switch113; the third pixel circuit112is connected with a corresponding data line; a corresponding control signal G3controls to switch on or off of the selector switch113. An OLED structure for emitting blue light (B-OLED) is connected with a fourth pixel circuit112through a selector switch113; the fourth pixel circuit112is connected with a corresponding data line; and a corresponding control signal G4controls to switch on or off of the selector switch113. Thus, when displaying each image frame, within a same pixel unit with the stacked structure, each selector switch connected with a respective subpixel unit for displaying a corresponding color can be selected to be switched on based on the actual color of the current image frame, so that the subpixel units for displaying the corresponding colors in the pixel unit with the stacked structure can be driven to emit light. Moreover, because the pixel circuits connected with different subpixel units are connected with different data lines, different data signals can be applied to different pixel circuits according to the current image frame, and hence an arbitrary display can be achieved. Therefore, a same pixel unit with the stacked structure can display the gray-scale display effect of different colors according to the difference of each image frame. Compared with the case that each subpixel unit can only display the gray-scale display effect of one color, the OLED display unit described above can improve the display effect because each pixel unit with the stacked structure can display the gray-scale display effect of more colors. Particularly, for the OLED display unit in which each pixel unit with the stacked structure at least includes subpixel units for emitting red light, subpixel units for emitting green light and subpixel units for emitting blue light, the perfect display effect can be achieved. The perfect display effect refers to that the pixel units can display the display effect of any gray scale of red, green and blue (RGB), so that the display effect can be maximally improved.

In at least one embodiment, in the OLED display unit provided by the embodiments of the present disclosure as illustrated inFIG. 3, the selector switches113are switching transistors; gate electrodes of the switching transistors are connected with control signals (G1, G2, G3and G4in the figure) to control the switching on or off of the switching transistors, respectively; drain electrodes of the switching transistors are connected with corresponding subpixel units111, respectively; and source electrodes of the switching transistors are connected with corresponding pixel circuits112, respectively. As illustrated inFIG. 3, the first subpixel unit for emitting red light (R-OLED) is connected with the first pixel circuit112through a switching transistor M1, and a gate electrode of the switching transistor M1is connected with the control signal G1; the second subpixel unit for emitting red light (R-OLED) is connected with the second pixel circuit112through a switching transistor M2, and a gate electrode of the switching transistor M2is connected with the control signal G2; the OLED structure for emitting green light (G-OLED) is connected with the third pixel circuit112through a switching transistor M3, and a gate electrode of the switching transistor M3is connected with the control signal G3; and the OLED structure for emitting blue light (B-OLED) is connected with the fourth pixel circuit112through a switching transistor M4, and a gate electrode of the switching transistor M4is connected with the control signal G4.

It should be noted that: in the OLED display unit provided by the embodiments of the present disclosure, when the number of the subpixel units in each pixel unit with the stacked structure is greater, the display effect is better. However, a greater quantity of the subpixel units indicates that a thickness of the OLED display unit is larger. Thus, in actual application, the number of the subpixel units in each pixel unit with the stacked structure can be determined by a balance between the display effect and the thickness of the display unit.

In the OLED display unit provided by the embodiments of the present disclosure, the number of the subpixel units in each pixel unit with the stacked structure may be equal or may also be unequal. No limitation will be placed here.

For instance, in the OLED display unit provided by the embodiments of the present disclosure, as illustrated inFIGS. 4ato 4f, each subpixel unit stacked group110in each pixel unit11with the stacked structure includes two subpixel units111, and the emitting colors of the four subpixel units111in the respective pixel unit11with the stacked structure are respectively red (R), blue (B), green (G) and red (R), or red (R), blue (B), green (G) and blue (B), or red (R), blue (B), green (G) and green (G).

In at least one embodiment, in order to simplify the manufacturing process, in the OLED display unit provided by the embodiments of the present disclosure, the sequence of the emitting colors of the four subpixel units in each pixel unit with the stacked structure is the same. That is, the pixel units each with the stacked structure have the same structure.

In at least one embodiment, in order to achieve a full-screen perfect display effect, all of the pixel units in the OLED display unit provided by the embodiments of the present disclosure are pixel units each with the stacked structure.

In a specific implementation, in the OLED display unit provided by the embodiments of the present disclosure, as illustrated inFIGS. 4ato 4f, the OLED structure generally includes an anode011, a light emission layer012and a cathode013which are stacked in sequence. The anode is generally made from indium tin oxide (ITO) materials. The cathode is generally made from transparent metallic materials.

For instance, in the OLED structure as illustrated inFIG. 5from the OLED display unit provided by the embodiments of the present disclosure, the light emission layer012may includes layers made from different organic materials, e.g., a hole injection layer (HIL)0121, a hole transport layer (HTL)0122, an organic light emission layer0123, an electron transport layer (ETL)0124and an electron injection layer (EIL)0125. The hole injection layer0121is close to the anode011and away from the cathode013. The electron injection layer0125is close to the cathode013and away from the anode011. As some other features of the OLED structure belongs to the art known by those skilled in the art, no further description will be given here.

In at least one embodiment, in order to simplify the structure, in the OLED display unit provided by the embodiments of the present disclosure, an electric potential of a cathode in each OLED structure of the same pixel unit with the stacked structure is equal. That is, each OLED structure in a same pixel unit with the stacked structure shares a cathode signal input terminal, so that the number of the cathode signal input terminals for inputting signals into the cathodes in the OLED display unit can be reduced. Of course, in a specific implementation, electric potentials of the cathodes in the OLED structures of the same pixel unit with the stacked structure may also be unequal. That is, the OLED structures are electrically connected with different cathode signal input terminals, respectively. No limitation will be placed herein.

In the OLED display unit provided by the embodiments of the present disclosure, an electric potential of a cathode of an OLED structure may be a negative voltage or may be zero. No limitation will be placed herein.

In at least one embodiment, in the OLED display unit provided by the embodiments of the present disclosure, as illustrated inFIGS. 6aand 6b, all of the pixel units11are pixel units each with the stacked structure; all of the pixel units11each with the stacked structure are arranged in a matrix; and in each pixel unit11with the stacked structure, two subpixel unit stacked group110are adjacent to each other along a row direction or a column direction.

Or in at least one embodiment, in the OLED display unit provided by the embodiments of the present disclosure, as illustrated inFIG. 7a, all of the pixel units11are pixel units11each with the stacked structure; all of the pixel units11each with the stacked structure are regularly arranged; in each pixel unit11with the stacked structure, two subpixel unit stacked groups110are adjacent to each other along the row direction; arrangement positions of odd rows of pixel units11each with the stacked structure correspond to each other, and arrangement positions of even rows of pixel units11each with the stacked structure correspond to each other; and in two adjacent rows of pixel units11each with the stacked structure, two subpixel unit stacked groups110which are adjacent to each other in position and have the same structure are misaligned.

For instance, in the OLED display unit as shown inFIG. 7a, not only the perfect display effect can be achieved but also the RGB virtual display pixel arrangement mode can be achieved by controlling different selector switches to be switched on. For instance, when display using the OLED display unit as shown inFIG. 7a, selector switches connected with a first layer of subpixel units111that are in odd rows of pixel units11with the stacked structure are switched on, where the first layer of subpixel units111is a layer close to a base substrate10; and selector switches connected with a second layer of subpixel units111that are in the odd rows of pixel units11with the stacked structure are switched off, where the second layer of subpixel units111is a layer away from the base substrate10. Meanwhile, selector switches connected with a first layer of subpixel units111that are in even rows of pixel units11with the stacked structure are switched off, where the first layer of subpixel units is a layer close to the base substrate10; and selector switches connected with a second layer of subpixel units111that are in the even rows of pixel units11with the stacked structure are switched on, where the second layer of subpixel units111is a layer away from the base substrate10. The specific effect is shown inFIG. 7b. Each subpixel unit stacked group110can achieve virtual display by adoption of the periodic pixel color borrowing means known by those skilled in the art.

Or in at least one embodiment, in the OLED display unit provided by the embodiments of the present disclosure, as illustrated inFIG. 8a, all of the pixel units11are pixel units11each with the stacked structure; all of the pixel units11with the stacked structure are regularly arranged; in each pixel unit11with the stacked structure, two subpixel unit stacked groups110are adjacent to each other along the column direction; arrangement positions of odd columns of pixel units each with the stacked structure correspond to each other, and arrangement positions of even columns of pixel units each with the stacked structure correspond to each other; and in two adjacent columns of pixel units11with the stacked structure, two subpixel unit stacked groups110which are adjacent to each other in position and have same structure are misaligned.

For instance, in the OLED display unit as shown inFIG. 8a, not only the perfect display effect can be achieved but also the RGB virtual display pixel arrangement mode can be achieved by controlling different selector switches to be switched on. For instance, when display using the OLED display unit as shown inFIG. 8a, selector switches connected with a first layer of subpixel units111that are in odd columns of pixel units11with the stacked structure are switched off, where the first layer of subpixel units111is a layer close to the base substrate10; and selector switches connected with a second layer of subpixel units111that are in the odd columns of pixel units11with the stacked structure are switched on, where the second layer of subpixel units111is a layer away from the base substrate10. Meanwhile, selector switches connected with a first layer of subpixel units111that are in even columns of pixel units11with the stacked structure are switched on, where the first layer of subpixel units is a layer close to the base substrate10; and selector switches connected with a second layer of subpixel units111that are in the even columns of pixel units11with the stacked structure are switched off, where the second layer of subpixel units111is a layer away from the base substrate10. The specific effect is shown inFIG. 8b. Each subpixel unit stacked group110can achieve virtual display by adoption of the periodic pixel color borrowing means known by those skilled in the art.

For instance, in the OLED display unit provided by the embodiments of the present disclosure, the pixel circuits have a compensation function and can effectively compensate the unevenness and the drift of the threshold voltage of the driving transistors in the pixel circuits, as well as the current difference caused by the unevenness of the OLEDs. There are many types of pixel circuits with compensation function in the field. No limitation will be placed herein.

The OLED display unit provided by the embodiments of the present disclosure will be described below with reference to a pixel circuit with a compensation function. For instance, as illustrated inFIG. 9, the pixel circuit112may include: a driving transistor T0, a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5and a capacitor C1. As for the first switching transistor T1, a source electrode is connected with a reference voltage terminal; a drain electrode is connected with a gate electrode of the driving transistor T0; and a gate electrode is configured to receive a first control signal EM. As for the second switching transistor T2, a gate electrode is configured to receive a first scanning signal Vscan1; a drain electrode is connected with a source electrode of the driving transistor T0; and a source electrode is configured to receive a data voltage signal Vdata. As for the third switching transistor T3, a gate electrode is configured to receive a second scanning signal Vscan2; a source electrode is connected with a drain electrode of the driving transistor T0; and a drain electrode is connected with a corresponding subpixel unit111. As for the fourth switching transistor T4, a source electrode is connected with the gate electrode of the driving transistor T0; a drain electrode is connected with the drain electrode of the driving transistor T0; and a gate electrode is configured to receive the first scanning signal Vscan1. As for the fifth switching transistor T5, a gate electrode is configured to receive the second scanning signal Vscan2; a source electrode is connected with the power voltage Vdd; and a drain electrode is connected with the source electrode of the driving transistor T0. The capacitor C1is connected between the reference voltage terminal and the gate electrode of the driving transistor T0.

For instance, in a specific implementation, in the OLED display unit provided by the embodiments of the present disclosure, the transistors are generally transistors made from the same materials. For instance, in a specific implementation, all the transistors are P-type transistors or N-type transistors. The N-type transistors are switched off under the action of a low voltage level and switched on under the action of a high voltage level. The P-type transistors are switched off under the action of a high voltage level and switched on under the action of a low voltage level.

It should be noted that the switching transistors and the driving transistor referred to in the above embodiments of the present disclosure may be TFTs and may also be metal-oxide-semiconductor field-effect transistors (MOSFETs). No limitation will be placed here. In a specific implementation, the functions of the source electrodes and the drain electrodes of the transistors can be interchanged according to different transistor types and different input signals. No specific distinction will be given here.

A display process of a subpixel unit of the OLED display unit provided by the embodiments of the present disclosure will be described below by taking the pixel circuit as shown inFIG. 9as an example. For instance, inFIG. 9, the driving transistor and all the switching transistors are all P-type transistors; a connection point between the drain electrode of the first switching transistor and the gate electrode of the driving transistor is taken as a first node A; and a connection point between the capacitor and the reference voltage terminal is taken as a second node B. A control timing sequence is shown inFIG. 10, and a display process of displaying each image frame includes three stages T1to T3. Suppose that the control signal G1controls the selector switch M1to be switched on when displaying the current image frame, so that a subpixel unit for emitting red light (R-OLED) is driven to display and emit light. A specific display process is as follows.

In the T1stage, Vscan1, Vscan2and G1are in a high voltage level, and EM is in a low voltage level. At this point, the switching transistor T1is switched on, and T2, T3, T4, T5and M1are switched off; charges stored in the first node A are released through T1; a voltage signal of the gate electrode of the driving transistor T0is reset; and the driving transistor T0is switched on.

In the T2stage, Vscan1and G1are in a low voltage level, and Vscan2and EM are in a high voltage level; the switching transistors T2, T4and M1are switched on and T1, T3and T5are switched off; and the driving transistor T0continues to maintain the on state. Due to T4being in an on state, the gate electrode and the drain electrode of the driving transistor T0are connected together; and the first node A is charged by the data signal Vdatathrough the driving transistor T0, so that the voltage of the first node A can be raised until the voltage of the first node A is Vdata−Vth. At this point, the quantity of electric charges Q of the capacitor C1is as follows:
Q=C·(V2−V1)=C·(VREF+Vth−Vdata)  (1),
where V1refers to the voltage of the first node A at this point and is equal to Vdata−Vth; and V2refers to the voltage of the second node B at this point and is equal to the voltage VREFof the reference voltage terminal. In the present disclosure, the reference voltage terminal is grounded, so the voltage VREFis 0.

In the T3stage, Vscan2and G1are in a low voltage level and scan1and EM are in a high voltage level. Thus, the switching transistors T3, T5and M1are switched on and T1, T2and T4are switched off; the capacitor C1maintains the voltage of the gate electrode of the driving transistor T0to be still Vdata−Vth; and the voltage of the source electrode of the driving transistor T0is the power voltage Vdd. In order to ensure the driving transistor T0being in the on state at this stage, when designed, the power voltage Vddis less than the data signal voltage Vdataand drives the B-OLED to emit light,
Vgs=Vs−Vg=Vdd+Vth−Vdata(2).

The gate source voltage Vgs of the driving transistor T0is maintained to be Vdd+Vth−Vdata. At this point, the current of the driving transistor T0is as follows:

As known from the above formula, the current of the driving transistor T0is only relevant to the power voltage Vddand the data voltage Vdataand irrelevant to the threshold voltage Vth. Therefore, the influence of the unevenness and the drift of the threshold voltage of the driving transistor and the unevenness of the electrical properties of the OLED structures can be eliminated, and hence the display effect can be further guaranteed.

The above embodiments are only described by taking the pixel circuit as shown inFIG. 9as an example. The working principle of the display process of all the subpixel units in the embodiments of the present disclosure is the same with the above description. No further description will be given here.

Based on the same inventive concept, at least one embodiment of the present disclosure further provides a method for driving the OLED display unit described above. As illustrated inFIG. 11, the method may comprise the following steps: S101that includes receiving video signals of images; and S102that includes controlling, based on corresponding colors of an image at corresponding positions of the pixel units in the OLED display unit, subpixel units that display light of the corresponding colors and that are in the pixel units at the corresponding positions to display, where the image corresponds to a video signal of a current image frame.

In the above driving method, each subpixel unit stacked group in each pixel unit with the stacked structure is controlled to display light of at least two colors according to video signals of a plurality of image frames. That is to say, in the process of displaying a plurality of image frames, the on or off state of each subpixel unit in each subpixel unit stacked group can be controlled, so that each subpixel unit stacked group can display light of at least two colors (that is, displaying the gray-scale effect of at least two colors).

In the method for driving the OLED display unit provided by the embodiments of the present disclosure, subpixel units for displaying light of corresponding colors in pixel units at corresponding positions can be controlled to display based on the color of an image at the positions of the pixel units in the OLED display unit, where the image corresponds to a video signal of the current image frame. Because part of the pixel units in the OLED display unit are pixel units with the stacked structure, each subpixel unit stacked group in each pixel unit with the stacked structure can display the gray-scale of a plurality of colors. Thus, compared with the case that a subpixel unit can only display the gray-scale effect of one color, a subpixel unit stacked group can be utilized to replace the subpixel unit that can only display the gray-scale effect of one color. Thus, the number of the colors displayed by each subpixel unit stacked group is increased compared to the subpixel unit that can only display the gray-scale effect of one color, and hence the display effect can be improved.

Based on the same inventive concept, correspondingly, for a structure that is the OLED display unit as shown inFIG. 7a, at least one embodiment of the present disclosure further provides a driving method. That is, in the OLED display unit, all the pixel units11are pixel units11each with the stacked structure, and all the pixel units11each with the stacked structure are regularly arranged; in each pixel unit11with the stacked structure, two subpixel unit stacked groups110are adjacent to each other along the row direction; arrangement positions of odd rows of pixel units11with the stacked structure correspond to each other, and arrangement positions of even rows of pixel units11with the stacked structure correspond to each other; and in two adjacent rows of pixel units11with the stacked structure, two subpixel unit stacked groups110which are adjacent to each other in position and have the same structure are misaligned. As illustrated inFIG. 12, the driving method comprises the following steps S201and S202. The steps will be described below one by one.

S201: during display of an odd image frame, controlling one subpixel unit layer in each odd row of pixel units with the stacked structure to emit light; and during display of an even image frame, controlling another subpixel unit layer in each odd row of pixel units with the stacked structure to emit light.

S202: during display of the odd image frame, controlling one subpixel unit layer in each even row of pixel units with the stacked structure to emit light; and during display of the even image frame, controlling another subpixel unit layer in each even row of pixel units with the stacked structure to emit light. Moreover, during display of each image frame, subpixel units which emit light and are in the odd rows of pixel units with the stacked structure and subpixel units which emit light and are in the even rows of pixel units with the stacked structure are in different layers.

For instance, during displaying an odd image frame: a layer of subpixel units that are in odd rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd rows is a layer close to a base substrate; and a layer of subpixel units that are in even rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even rows is a layer away from the base substrate. During displaying an even image frame: a layer of subpixel units that are in the odd rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd rows is a layer away from the base substrate; and a layer of subpixel units that are in the even rows of pixel units with the stacked structure is controlled to emit light, where the layer of the subpixel units in the even rows is a layer close to the base substrate. Or, during displaying an odd image frame: a layer of subpixel units that are in even rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even rows is a layer close to the base substrate; and a layer of subpixel units that are in odd rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd rows is a layer away from the base substrate. During displaying an even image frame: a layer of subpixel units that are in the even rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even rows is a layer away from the base substrate; and a layer of subpixel units that are in the odd rows of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd rows is a layer close to the base substrate.

As such, for two adjacent image frames, different subpixel units are adopted to achieve the virtual display pixel arrangement effect. Moreover, as the subpixel units only display during a time duration of one image frame for two image frames, the service life of the OLED display unit can be prolonged on the basis of achieving virtual display.

Correspondingly, for a structure that is the OLED display unit as shown inFIG. 8a, at least one embodiment of the present disclosure further provides a driving method. That is, in the OLED display unit, all the pixel units11are pixel units11each with the stacked structure, and all the pixel units11each with the stacked structure are regularly arranged; in each pixel unit11with the stacked structure, two subpixel unit stacked groups110are adjacent to each other along the column direction; arrangement positions of odd columns of pixel units11with the stacked structure correspond to each other, and arrangement positions of even columns of pixel units11with the stacked structure correspond to each other; and in two adjacent columns of pixel units11with the stacked structure, two subpixel unit stacked groups110which are adjacent to each other in position and have the same structure are misaligned. As illustrated inFIG. 13, the driving method comprises the steps S301and S302. The steps will be described below one by one.

S301: during display of an odd image frame, controlling one subpixel unit layer in each odd column of pixel units with the stacked structure to emit light; and during display of an even image frame, controlling another subpixel unit layer in each odd column of pixel units with the stacked structure to emit light.

S302: during display of the odd image frame, controlling one subpixel unit layer in each even column of pixel units with the stacked structure to emit light; and during display of the even image frame, controlling another subpixel unit layer in each even column of pixel units with the stacked structure to emit light. Moreover, during display of each image frame, subpixel units which emit light and are in the odd columns of pixel units with the stacked structure and subpixel units which emit light and are in the even columns of pixel units with the stacked structure are in different layers.

For instance, during displaying an odd image frame: a layer of subpixel units that are in odd columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd columns is a layer close to a base substrate; and a layer of subpixel units that are in even columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even columns is a layer away from the base substrate. During displaying an even image frame: a layer of subpixel units that are in the odd columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd columns is a layer away from the base substrate; and a layer of subpixel units that are in the even columns of pixel units with the stacked structure is controlled to emit light, where the layer of the subpixel units in the even columns is a layer close to the base substrate. Or, during displaying an odd image frame: a layer of subpixel units that are in even columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even columns is a layer close to the base substrate; and a layer of subpixel units that are in odd columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd columns is a layer away from the base substrate. During displaying an even image frame: a layer of subpixel units that are in the even columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the even columns is a layer away from the base substrate; and a layer of subpixel units that are in the odd columns of pixel units with the stacked structure is controlled to emit light, where the layer of subpixel units in the odd columns is a layer close to the base substrate.

As such, for two adjacent image frames, different subpixel units are adopted to achieve the virtual display pixel arrangement effect. Moreover, as the subpixel units only display in a time duration of one image frame for two image frames, the service life of the OLED display unit can be prolonged on the basis of achieving virtual display.

Based on the same inventive concept, at least one embodiment of the present disclosure further provides a display device, which comprises any foregoing OLED display unit provided by the embodiments of the present disclosure. The display device may include: any product or component with a display function such as a mobile phone, a tablet PC, a TV, a display, a notebook computer, a digital picture frame and a navigator, etc. All the other necessary components of the display device should be understood by those skilled in the art, should not be further described here, and should not be construed as the limitation of the present disclosure. The embodiments of the display device may refer to the embodiments of the foregoing OLED display unit. No further description will be given here.

In the OLED display unit, the driving method thereof and the display device provided by the embodiments of the present disclosure, at least part of pixel units are pixel units each with a stacked structure; each pixel unit with the stacked structure includes two adjacent subpixel unit stacked groups; each subpixel unit stacked group includes at least two subpixel units which have different emitting colors and are stacked and insulated from each other; and the number of the subpixel units in each of the subpixel unit stacked groups of the same pixel unit with the stacked structure is the same. Therefore, during display of different image frames, each subpixel unit stacked group in each pixel unit with the stacked structure can display the gray-scale effect of at least two colors according to applied signals. Compared with the case that each subpixel unit can only display the gray-scale effect of one color for different image frames, the OLED display unit described above can improve the display effect because each subpixel unit stacked group can display more colors. In addition, in each same pixel unit with the stacked structure from the pixel units each with the stacked structure, only one subpixel unit layer includes two subpixel units that have the same emitting color, and one or more other subpixel unit layers each include two subpixel units that have different emitting colors. Therefore, during display, the virtual display pixel arrangement effect can be also achieved by the control of the light emission of the subpixel units in different layers.

The foregoing is only the preferred embodiments of the present disclosure and not intended to limit the scope of protection of the present disclosure. The scope of protection of the present disclosure should be defined by the appended claims.

The application claims priority to the Chinese patent application No. 201410515749.X, filed on Sep. 29, 2014, the disclosure of which is incorporated herein by reference in its entirety as part of the application.