Display panel and display device

Abstract

The application discloses a display panel and a display device. The display panel comprises a plurality of light emitting elements and a driving circuit electrically connected with a pixel anode of each light emitting element. The driving circuit comprises a voltage stabilizing capacitor for stabilizing the voltage transmitted to the pixel anode. The voltage stabilizing capacitor comprises a first capacitor and a second capacitor. Part of the pixel anodes are arranged opposite to the pixel cathodes to form two plates of the first capacitor. Part of the pixel anodes extend into the pixel definition layer and are arranged opposite to the auxiliary cathodes to form two plates of the second capacitor. The pixel cathode extends to the surface of the pixel definition layer and is connected with the auxiliary cathode on the surface of the pixel definition layer, so that the first capacitor and the second capacitor are connected in communication. The above structure improves the stability of the driving circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of display, in particular to a display panel and a display device. BACKGROUND

[0002] With the development of display panels, for the internal compensation circuit in the OLED display panel, as its application size gradually popularizes from mobile phone products to medium-sized products, and its product refresh rate develops from 60hz to 120Hz or even higher, it is easy to have the problems of poor compensation effect and low yield.

[0003] As a simple structure of internal compensation circuit, in the 4T2C circuit driving timing, the compensation stage and the writing stage share one row scanning cycle time, with the higher refresh rate, the shorter row cycle time, which will inevitably lead to the problem of insufficient compensation time and poor compensation effect.

[0004] Therefore, in order to further compress the pixel size and improve the compensation stability of the compensation circuit, the circuit architecture of 4T2C needs to be further optimized. SUMMARY

[0005] The technical problem solved by the present application is to provide a display panel and a display device to improve the stability of the driving circuit.

[0006] To solve the above problems, the first aspect of the present application provides a display panel, which comprises a plurality of light emitting elements and a driving circuit electrically connected to a pixel anode of each light emitting element; each light emitting element comprises: the pixel anode; a pixel definition layer covering part of the surface of the pixel anode and exposing part of the surface of the pixel anode to form a pixel opening; an organic light emitting layer arranged on the surface of the pixel anode in the pixel opening; a pixel cathode arranged on the surface of the organic light emitting layer in the pixel opening; a overhang structure arranged on the surface of the pixel definition layer away from the pixel anode, the overhang structure comprising an auxiliary cathode arranged on the pixel definition layer away from the pixel anode and an insulating structure arranged on the surface of the auxiliary cathode away from the pixel definition layer; the driving circuit comprises a voltage stabilizing capacitor for maintaining the voltage transmitted to the pixel anode stable, the voltage stabilizing capacitor comprising a first capacitor and a second capacitor; part of the pixel anode and the pixel cathode are arranged opposite to each other to form two plates of the first capacitor; part of the pixel anode extends into the pixel definition layer and is arranged opposite to the auxiliary cathode to form two plates of the second capacitor; wherein the pixel cathode extends to the surface of the pixel definition layer and is connected to the auxiliary cathode on the surface of the pixel definition layer, so that the first capacitor and the second capacitor are connected in communication.

[0007] Preferably, the upper surface of the pixel anode disposed opposite to the auxiliary cathode is higher than the upper surface of the pixel anode disposed opposite to the pixel cathode, so as to reduce the distance between the pixel anode and the auxiliary cathode and increase the capacity of the second capacitor.

[0008] Preferably, the thickness of the pixel anode disposed opposite to the auxiliary cathode is greater than the thickness of the pixel anode disposed opposite to the pixel cathode, so as to increase the capacity of the second capacitor.

[0009] Preferably, the pixel anode disposed opposite to the auxiliary cathode comprises a first anode and a second anode, the first anode and the second anode are disposed in a stacking direction; wherein the second anode is disposed on the side of the first anode away from the auxiliary cathode, so as to reduce the distance between the first anode and the auxiliary cathode; or, the second anode is disposed on the side of the first anode close to the auxiliary cathode, so as to reduce the distance between the second anode and the auxiliary cathode; wherein the second anode is made of conductive material; wherein the pixel anode disposed opposite to the pixel cathode comprises the first anode or the second anode.

[0010] Preferably, a plurality of the light emitting elements are arranged in an array on a planar layer of a driving substrate, the planar layer is provided with a groove at a position corresponding to the pixel opening, a part of the pixel anode is disposed in the groove and disposed opposite to the pixel cathode; another part of the pixel anode is disposed protruding above the surface of the groove and disposed opposite to the auxiliary cathode.

[0011] To solve the above problems, the second aspect of the present application provides a driving circuit, comprising: a driving transistor connected to the pixel anode of each light emitting element; a first driving circuit connected to one end of each driving transistor, the input end of the first driving circuit is connected to a data line, for receiving a data voltage and transmitting to each driving transistor; a second driving circuit connected to the input end of a plurality of driving transistors, the input end of the second driving circuit is connected to a power supply line, for receiving a power supply voltage and transmitting to the driving transistor; a storage capacitor, the first plate of the storage capacitor is connected to the control end of the driving transistor, and the second plate of the storage capacitor is connected to the pixel anode of the light emitting element; a voltage stabilizing capacitor, the first plate of the voltage stabilizing capacitor is connected to the second plate of the storage capacitor and the pixel anode of the light emitting element, and the second plate of the voltage stabilizing capacitor is connected to the pixel cathode of the light emitting element and the auxiliary cathode.

[0012] Preferably, the first driving circuit comprises a data writing transistor and a compensation transistor connected to the control terminal of the driving transistor; the control terminal of the data writing transistor is connected to a scan line, the input terminal is connected to a data line, and the output terminal is connected to the control terminal of the driving transistor, for writing data voltage to the driving transistor; the control terminal of the compensation transistor is connected to a compensation control line, the input terminal is connected to a compensation signal line, and the output terminal is connected to the control terminal of the driving transistor, for writing compensation voltage containing threshold voltage to the driving transistor.

[0013] Preferably, the second driving circuit comprises a switch transistor for controlling the light emitting element to emit light, and a reset transistor for resetting the pixel anode of the light emitting element; the control terminal of the switch transistor is connected to a switch control line, the input terminal is connected to a power line, and the output terminal is connected to the input terminal of a plurality of the driving transistor, for controlling the driving transistor to drive the light emitting element to emit light; the control terminal of the reset transistor is connected to a reset control line, the input terminal is connected to a reset signal line, and the output terminal is connected to the input terminal of a plurality of the driving transistor, for charging the reset signal to the pixel anode of the light emitting element through the driving transistor.

[0014] To solve the above problems, the third aspect of the present application provides a driving method for driving the pixel driving circuit according to any one of the second aspect, comprising: a reset stage, the switch control line of the Nth row controls the switch transistor to be closed, the compensation control line of the Nth row controls the compensation transistor to be closed, the scan line of the Nth row controls the data write transistor to be closed, and the reset signal line of the Nth row controls the reset transistor to be opened, so that the control end of the driving transistor retains the voltage of the last frame and is opened under the action of the voltage of the last frame, the reset voltage is written to the pixel anode of the light emitting element through the driving transistor, the reset of the light emitting element is realized, and the light emitting element does not emit light; a compensation stage, the switch control line of the Nth row controls the switch transistor to be opened, the compensation control line of the Nth row controls the compensation transistor to be opened, the scan line of the Nth row controls the data write transistor to be closed, and the reset signal line of the Nth row controls the reset transistor to be closed, so that the input end of the driving transistor writes the power supply voltage, the control end of the driving transistor writes the compensation voltage, the driving transistor is controlled to be opened under the compensation voltage, the power supply voltage is charged to the output end of the driving transistor, until the gate-source voltage of the driving transistor is close to the threshold voltage, the driving transistor is closed, and the light emitting element does not emit light; a data write stage, the switch control line of the Nth row controls the switch transistor to be closed, the compensation control line of the Nth row controls the compensation transistor to be closed, the scan line of the Nth row controls the data write transistor to be opened, and the reset signal line of the Nth row controls the reset transistor to be closed, so that the control end of the driving transistor writes the data voltage, and the light emitting element does not emit light; and a light emitting stage, the switch control line of the Nth row controls the switch transistor to be opened, the compensation control line of the Nth row controls the compensation transistor to be closed, the scan line of the Nth row controls the data write transistor to be closed, and the reset signal line of the Nth row controls the reset transistor to be closed, so that the driving transistor generates a driving current under the action of the data voltage, and drives the light emitting element to emit light.

[0015] To solve the above problems, the fourth aspect of the present application provides a display device, which comprises the display panel according to any one of the first aspect.

[0016] The present application has the beneficial effect that by connecting the voltage stabilizing capacitors in the driving circuit to the pixel anode and the pixel cathode and the auxiliary cathode, when the capacitance between the pixel cathode and the pixel anode reaches the maximum, the capacitance value between the pixel anode and the auxiliary cathode is increased, thereby improving the stability of the voltage of the pixel anode. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative labor.

[0018] Figure 1 The structural schematic diagram of an embodiment of the display panel of the present application is shown in the figure.

[0019] Figure 2 The structural schematic diagram of a first specific embodiment of the display panel of the present application is shown in the figure.

[0020] Figure 3 The structural schematic diagram of a second specific embodiment of the display panel of the present application is shown in the figure.

[0021] Figure 4 The structural schematic diagram of a specific embodiment of the display panel of the present application is shown in the figure.

[0022] Figure 5 The structural schematic diagram of an embodiment of the driving circuit of the present application is shown in the figure.

[0023] Figure 6 The structural schematic diagram of a specific embodiment of the driving circuit of the present application is shown in the figure.

[0024] Figure 7 The timing control diagram of a specific embodiment of the driving method of the driving circuit of the present application is shown in the figure.

[0025] 10 driving circuit; OLED light emitting element; 11 first driving circuit; 12 second driving circuit; T1 data writing transistor; T2 compensation transistor; DT driving transistor; Td switching transistor; Ti reset transistor; C2 voltage stabilizing capacitor; C1 storage capacitor; VDD power supply line; Scan scanning line; Data data line; REF compensation control line; ref compensation signal line; EM switching control line; INI reset control line; int reset signal line; 100 driving substrate; 101 pixel anode; 102 organic light emitting layer; 103 pixel cathode; PDL pixel definition layer; OH overhang structure; 104 auxiliary cathode; 105 eave layer. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0027] The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the description of the application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be understood that the terms "and / or", "at least one of", "one or more of", and "and / or at least one of", used herein in the description and in the claims, are open-ended expressions that are intended to mean that there is at least one, but it is not exclusive, and can include zero, one, two, three, four, five, six or more term(s) or element(s).

[0028] It should be understood that the term "and / or" as used herein is merely an associative relationship of the associated objects, and means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this specification and claims and the above-mentioned drawings generally means that the front and rear associated objects are in an "or" relationship. The terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily mean a specific order or sequence.

[0029] It should be understood that the terms "include", "contain" or any other variation used herein are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device. Without more limitations, the elements defined by the statement "include" do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0030] It should be noted that if the directionality indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of the present application, the directionality indication is only used to explain the relative position relationship, motion condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indication also changes accordingly.

[0031] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in question in various places in the specification are not necessarily all referring to the same embodiment, or are necessarily referring to different or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with each other.

[0032] The application provides a display panel, please refer to Figure 1 , Figure 1 is a structural schematic diagram of an embodiment of the display panel of the present application. As Figure 1As shown, the display panel comprises a plurality of light emitting elements OLED and driving circuits electrically connected to the pixel anodes of each light emitting element OLED. The driving circuit can be any of the driving circuits described in the above embodiments, which will not be described herein.

[0033] The driving circuit comprises a voltage stabilizing capacitor C2 for stabilizing the voltage transmitted to the pixel anode 101, the voltage stabilizing capacitor C2 comprising a first capacitor Cac connecting the pixel anode and the pixel cathode, and a second capacitor Cao connecting the pixel anode and the auxiliary cathode.

[0034] Each light emitting element OLED comprises a pixel anode 101, a pixel definition layer PDL, an organic light emitting layer 102, a pixel cathode 103, and an auxiliary cathode 104. The pixel definition layer PDL covers part of the surface of the pixel anode 101 and exposes another part of the surface of the pixel anode 101 to form a pixel opening. The organic light emitting layer 102 is disposed on the surface of the pixel anode 101 within the pixel opening. The pixel cathode 103 is disposed on the surface of the organic light emitting layer 102 within the pixel opening and is spaced apart from the pixel anode 101 to form the first capacitor Cac. The auxiliary cathode 104 is disposed on the surface of the pixel definition layer PDL away from the pixel anode 101 to be spaced apart from the pixel anode 101 to form the second capacitor Cao.

[0035] In this embodiment, when the pixel opening reaches the maximum, that is, when the first capacitor Cac formed by the pixel anode 101 and the pixel cathode 103 reaches the maximum, the stability of the voltage stabilizing capacitor C2 is further improved by increasing the capacitance value of the second capacitor Cao, thereby improving the stability of the voltage of the pixel anode 101.

[0036] The pixel anode 101 extends at least on one side in the direction of the auxiliary cathode 104 and at least partially overlaps the auxiliary cathode 104 in the vertical projection plane to form the second capacitor Cao with the auxiliary cathode 104. In other specific embodiments, the pixel anode 101 can extend on both sides in the direction of the pixel definition layer PDL on both sides to form two second capacitors Cao with the auxiliary cathode 104 on the pixel definition layer PDL on both sides, respectively. Further, the pixel anode 101 can also extend on four sides in the direction of the pixel definition layer PDL on four sides, which will not be specifically limited here. Preferably, the pixel anode 101 extends on one side in the direction of the auxiliary cathode 104. The extension length can be greater than 1 / 2 of the pixel definition layer PDL, and the pixel anodes 101 of the plurality of light emitting elements OLED extend in the same direction to ensure that the capacitances in each light emitting element OLED are approximately the same. When the pixel anode 101 extends on at least two sides in the direction of the auxiliary cathode 104, in order to be spaced apart from the adjacent pixel anode 101, the extension length of the pixel anode 101 needs to be less than 1 / 2 of the pixel definition layer PDL.

[0037] In this embodiment, the pixel cathode 103 extends to the surface of the pixel definition layer PDL and connects to the auxiliary cathode 104 on the surface of the pixel definition layer PDL, thereby connecting the first capacitor Cac and the second capacitor Cao to form a voltage regulator capacitor C2. In other embodiments, the first capacitor Cac and the second capacitor Cao may not be connected.

[0038] In one embodiment, by making the height of the pixel anode 101 at the position where it overlaps with the auxiliary cathode 104 greater than the height of the pixel anode 101 at the position where it overlaps with the pixel cathode 103, that is, by raising the pixel anode 101 at the position where it overlaps with the auxiliary cathode 104, the distance between the pixel anode 101 and the auxiliary cathode 104 is reduced, that is, the distance between the two plates of the second capacitor Cao is shortened, and the capacitance value of the second capacitor Cao is increased.

[0039] In another embodiment, the second capacitor Cao is increased by making the thickness of the pixel anode 101 at the overlapping position with the auxiliary cathode 104 greater than the thickness of the pixel anode 101 at the overlapping position with the pixel cathode 103. In a specific embodiment, the technical means includes: increasing the thickness of the pixel anode 101 at the overlapping position with the auxiliary cathode 104.

[0040] It should be noted that the height or thickness of the pixel anode 101 at the overlapping position with the pixel cathode 103 is a reference value, which is set according to the light emission requirements of the OLED light-emitting element.

[0041] In one specific embodiment, the pixel anode 101 has a first anode 1011 and a second anode 1012 disposed at the overlapping position with the auxiliary cathode 104, and the first anode 1011 and the second anode 1012 are disposed overlapping in the stacking direction. The first anode 1011 is the main anode, and it overlaps with both the pixel cathode 103 and the auxiliary cathode 104 in the stacking direction. The stacking direction is also perpendicular to the projection plane direction.

[0042] For details, please refer to [link / reference]. Figure 2 , Figure 2 This is a schematic diagram of the structure of a first specific embodiment of the display panel of this application. Figure 2 As shown, the second anode 1012 is disposed on the side of the first anode 1011 away from the auxiliary cathode 104, so as to raise the first anode 1011 and reduce the distance between the first anode 1011 and the auxiliary cathode 104. In this specific embodiment, the second anode 1012 can be a non-conductive material, such as resin, or a conductive material, which is not limited here.

[0043] For more details, please refer to [link / reference]. Figure 3 , Figure 3 This is a schematic diagram of the structure of a second specific embodiment of the display panel of this application.Figure 3 As shown, the second anode 1012 is disposed on the side of the first anode 1011 close to the auxiliary cathode 104. The second anode 1012 is made of conductive material, and the first anode 1011 is used to elevate the second anode 1012, so as to shorten the distance between the second anode 1012 and the auxiliary cathode 104. In a specific embodiment, the material of the second anode 1012 can be the same as or different from that of the first anode 1011. Specifically, the first anode 1011 is made of ITO material which is transparent, and the second anode 1012 can be made of ITO material or metal material which is not transparent, which is not limited herein. When the material of the first anode 1011 is the same as that of the second anode 1012, it can be understood that the pixel anode 101 at the position overlapping with the auxiliary cathode 104 is thickened, which is not exemplified herein.

[0044] Further, reference can be made to Figure 4 , Figure 4 is a structural schematic diagram of a specific embodiment of the display panel. A plurality of light emitting elements OLED are arranged in an array on a planar layer of a driving substrate 100. The driving substrate 100 includes an array substrate, and each transistor in the driving circuit 10 is disposed in the driving substrate 100, and the surface of the driving substrate 100 is provided with a planar layer. In the above specific embodiment, the pixel anode 101 of the plurality of light emitting elements OLED is disposed on the surface of the planar layer of the driving substrate 100. In a further embodiment, the planar layer on the surface of the driving substrate 100 is provided with a groove, as shown in Figure 4 As shown, part of the pixel anode 101 is disposed in the groove of the driving substrate 100, and part of the pixel anode 101 is disposed on the surface of the groove. The pixel anode 101 disposed in the groove overlaps with the pixel cathode 103 in the stacking direction to form a first capacitor Cac. The pixel anode 101 disposed on the surface of the groove overlaps with the auxiliary cathode 104 in the stacking direction to form a second capacitor Cao. In a specific embodiment, two planar layers can be provided, and a groove is formed on the surface of the uppermost planar layer, which is not limited to the specific embodiment. In the embodiment, the pixel anode 101 of the light emitting area of the light emitting element OLED is lowered by the groove of the driving substrate 100, and the pixel anode 101 is elevated by the structure around the groove.

[0045] Further, in the embodiment, the overhang structure OH is arranged on the pixel definition layer PDL to separate two adjacent light emitting elements. The overhang structure OH includes the auxiliary cathode 104 and the roof layer 105 with a width larger than the auxiliary cathode 104, wherein the width refers to the length along the stacking direction. By making the width of the roof layer 105 larger than the width of the auxiliary cathode 104, the FMM (maskless) evaporation process can be used to fabricate the organic light emitting layer 102 and the pixel cathode 103 of the light emitting element OLED. Specifically, the organic light emitting layer 102 is interrupted by the overhang structure OH. The organic light emitting layer 102 includes a red light emitting layer R, a green light emitting layer G, a blue light emitting layer B, etc., which are not limited herein.

[0046] In the embodiment, by using the overhang structure and the FMM evaporation process to fabricate the light emitting element OLED, each light emitting element OLED can have a larger aperture ratio, thereby increasing the capacitance Cac between the pixel anode 101 and the pixel cathode 103 of the light emitting element.

[0047] Further, the auxiliary cathode layer 104 connects the pixel cathodes 103 of adjacent light emitting elements OLED, thereby connecting the pixel cathodes 103 of the entire display panel to form a full-surface pixel cathode 103. The auxiliary cathode layer 104 and the pixel anode 101 of the light emitting element OLED are arranged in an overlapping manner in a direction perpendicular to the stacking surface, thereby forming a part Cao of the stabilizing capacitor C2. The pixel cathode 103 of the light emitting element and the pixel anode 101 of the light emitting element form another part Cac of the stabilizing capacitor C2. Cao and Cac constitute the stabilizing capacitor C2.

[0048] The capacity of the stabilizing capacitor C2 is positively correlated with the overlapping area between the pixel anode 101 of the light emitting element, the pixel cathode 103 of the light emitting element, and the auxiliary cathode 104. The capacity of the stabilizing capacitor C2 is correlated with the capacities of Cao and Cac, i.e., the first capacitor Cac formed by the overlapping of the pixel anode 101 and the pixel cathode 103 of the light emitting element OLED and the second capacitor Cao formed by the overlapping of the pixel anode 101 and the auxiliary cathode 104, wherein Cac and Cao are respectively correlated with the overlapping areas of their two plates. In a specific embodiment, the aperture ratio of the light emitting element can be increased by using the FMM evaporation process, i.e., the overlapping area of the pixel anode 101 and the pixel cathode 103 of the light emitting element is increased, thereby increasing the capacity of the stabilizing capacitor C2. In another specific embodiment, the pixel anode 101 of the light emitting element can be extended towards the overhang structure OH, thereby increasing the overlapping area between the pixel anode 101 of the light emitting element and the auxiliary cathode 104, and increasing the capacity of the stabilizing capacitor C2. The capacity refers to the amount of charge that can be stored by the capacitor. In other embodiments, both the aperture ratio and the capacity of the stabilizing capacitor C2 can be increased, which are not limited herein.

[0049] This application also provides a driving circuit, please refer to the details. Figure 5 , Figure 5 This is a schematic diagram of the structure of one embodiment of the driving circuit of this application. Figure 5 As shown, the driving circuit includes a light-emitting element (OLED), a driving circuit 10 electrically connected to the pixel anode of the OLED, and a voltage regulator capacitor C2 for maintaining a stable voltage input from the driving circuit 10 to the anode of the OLED. The first plate of the voltage regulator capacitor C2 is electrically connected to the output terminal of the driving circuit 10 and the pixel anode of the OLED, and the second plate of the voltage regulator capacitor C2 is electrically connected to the pixel cathode and the auxiliary cathode of the OLED.

[0050] Specifically, the driving circuit 10 includes a first driving circuit 11 electrically connected to each light-emitting element (OLED) and a second driving circuit 12 electrically connected to multiple light-emitting elements (OLEDs) simultaneously. The driving circuit 10 includes at least a driving transistor DT. The output terminal of each driving transistor DT is connected to the anode of each light-emitting element (OLED), the control terminal of each driving transistor DT is connected to each of the first driving circuits 11, and the input terminals of the multiple driving transistors DT are connected to a second driving circuit 12. In one specific embodiment, multiple sub-pixels in the same row can be connected to the same second driving circuit 12, or all sub-pixels in an entire row can be connected to the same second driving circuit 12. Each sub-pixel includes one light-emitting element. Preferably, three sub-pixels (i.e., one pixel unit) share one second driving circuit 12. On the one hand, compared to a single sub-pixel requiring a separate second driving circuit 12, this simplifies the circuit design of a single sub-pixel and helps increase the aperture ratio of a single sub-pixel. On the other hand, compared to a row of sub-pixels sharing a single second driving circuit 12, this avoids excessive load on a single power line VDD, which would require increasing the width of the power line VDD to prevent burnout and poor signal transmission.

[0051] For details, please refer to further information. Figure 6 , Figure 6 This is a schematic diagram of a specific embodiment of the driving circuit of this application. Figure 6 As shown, the first driving circuit 11 includes a data writing circuit connected to the control terminal of the driving transistor DT. The data writing circuit is used to write data voltage.

[0052] Preferably, the data writing circuit comprises a data writing transistor T1, wherein the control terminal of the data writing transistor T1 is connected with the scan line Scan, the input terminal is connected with the data line Data, and the output terminal is connected with the control terminal of the driving transistor DT. In the data writing stage, the data voltage Vdata is written to the control terminal of the driving transistor DT through the data writing transistor T1, so as to control the current input to the light emitting element OLED, thereby controlling the light emitting brightness of the light emitting element OLED. In other embodiments, the data writing circuit can also comprise other data writing transistors, which are not limited herein.

[0053] Further, the first driving circuit 11 further comprises a compensation circuit. Preferably, the compensation circuit comprises a compensation transistor T2 and a storage capacitor C1. Specifically, the control terminal of the compensation transistor T2 is connected with the compensation control line REF, the input terminal is connected with the compensation signal line ref, and the output terminal is connected with the control terminal of the driving transistor DT, for inputting the compensation voltage Vref to the control terminal of the driving transistor DT. The first plate of the storage capacitor C1 is connected with the control terminal of the driving transistor DT, and the second plate of the storage capacitor C1 is connected with the output terminal of the driving transistor DT.

[0054] It should be noted that the driving transistor DT in the present application is an N-type transistor, the control terminal of the driving transistor DT is the gate, the output terminal is the source, and the input terminal is the drain. The driving current flowing through the driving transistor DT is related to the driving voltage of the gate-source voltage VGS of the driving transistor DT, that is, related to the voltage difference between the N1 node and the N3 node.

[0055] In the present embodiment, the gate and the source of the driving transistor DT are connected through the storage capacitor C1, so that the voltage containing the threshold voltage of the driving transistor DT can be charged to the gate of the driving transistor DT, so that the driving transistor DT is not affected by the drift of the threshold voltage of the driving transistor DT when driving the light emitting element OLED to emit light, thereby making the display brightness more stable.

[0056] In other embodiments, the compensation voltage containing the threshold voltage can also be charged to the gate of the driving transistor DT through other compensation circuits, for example, directly charging the compensation voltage through the data line Data, and the like, which are not limited herein. It should be noted that the embodiments in the present application are preferred embodiments of the present application, and are not limited to the embodiments.

[0057] Further, the second driving circuit 12 comprises a switch circuit for controlling the light emitting element OLED to emit light. Preferably, the switch circuit comprises a switch transistor Td. The control terminal of the switch transistor Td is connected with the switch control line EM, the input terminal is connected with the power line VDD, and the output terminal is connected with the input terminals of the plurality of driving transistors DT, for controlling whether the driving transistor DT drives the light emitting element OLED to emit light and when to emit light. Specifically, in the light emitting stage, the switch circuit inputs a voltage to the input terminal of the driving transistor DT, so that the input terminal and the output terminal of the driving transistor DT generate a voltage difference, thereby controlling the driving transistor DT to drive the light emitting element OLED to emit light. In the present embodiment, in the compensation stage, the switch circuit is also turned on, and the input terminal of the driving transistor DT is connected with the power line through the switch circuit, so that the source and the drain of the driving transistor DT have a voltage difference, thereby having a current flow, and then the output terminal N3 of the driving transistor DT is charged / discharged through the input terminal N2 of the driving transistor DT, so that the voltage of the output terminal (i.e. the source) N3 of the driving transistor DT contains the threshold voltage Vth, so that the driving transistor can achieve voltage compensation. It should be noted that the input terminal and the output terminal in the present application are not limited to the direction of current flow. When the voltage of the output terminal is higher than the voltage of the input terminal, the output terminal can be reversely charged, that is, the voltage of the output terminal flows to the input terminal.

[0058] In other embodiments, other circuits can also be used to control when the light emitting element OLED emits light, which is not limited herein.

[0059] Further, the second driving circuit comprises a reset circuit for resetting the anode of the light emitting element OLED. Preferably, the reset circuit comprises a reset transistor Ti. The control terminal of the reset transistor Ti is connected with the reset control line INI, the input terminal is connected with the reset signal line int, and the output terminal is connected with the input terminals of the plurality of driving transistors DT, so as to charge the reset signal Vint to the anode of the light emitting element OLED through the driving transistor DT. Specifically, in the reset stage, the reset transistor Ti inputs the reset signal to the input terminals of the plurality of driving transistors DT, and at the same time, the driving transistor DT remains in the on state under the influence of the previous frame, so that the reset voltage Vint of the reset signal line int is output to the output terminal through the input terminal of the driving transistor DT, and then to the anodes of the plurality of light emitting elements OLED.

[0060] Further, the driving circuit comprises a data writing circuit, a compensation capacitor, a switch circuit, a reset circuit, etc., that is, it comprises a plurality of transistors as shown in Figure 6 The driving method of the driving circuit specifically comprises: a reset stage, a compensation stage, a data writing stage, and a light emitting stage.

[0061] Specifically, further refer to Figure 7 ,Figure 7 Figure 1 is a timing control diagram of a specific embodiment of a driving method of a driving circuit of the present application. The driving circuit includes Figure 6 a specific driving circuit shown in Figure 2.

[0062] In the reset stage, the switch control line EM(n) of the Nth row controls the switch transistor Td to be closed, the compensation control line REF(n) of the Nth row controls the compensation transistor T2 to be closed, the scan line Scan(n) of the Nth row controls the data write transistor T1 to be closed, and the reset signal line INI(n) of the Nth row controls the reset transistor Ti to be opened. At this time, the control end N1 node of the driving transistor DT retains the voltage of the last frame, and since the voltage is higher than the Vint voltage, the driving transistor DT can be opened, so that the reset voltage Vint on the reset signal line int can be written to the N3 node (the output end of the driving transistor), thereby resetting the anode of the light emitting element OLED, so that the light emitting element OLED does not emit light. After the reset stage is completed, the voltage VN3 of the N3 node is Vint.

[0063] In the compensation stage, the switch control line EM(n) of the Nth row controls the switch transistor Td to be opened, the compensation control line REF(n) of the Nth row controls the compensation transistor T2 to be opened, the scan line Scan(n) of the Nth row controls the data write transistor T1 to be closed, and the reset signal line INI(n) of the Nth row controls the reset transistor Ti to be closed. At this time, the voltage of the power supply line VDD is written to the N2 node (the input end of the driving transistor DT), and the N1 node is written with the compensation voltage Vref voltage, which is greater than the voltage of the N3 node, so as to control the driving transistor DT to be opened, and the power supply line VDD charges the N3 node. When the voltage of the N3 node rises from the Vint in the reset stage to Vref-Vth, the driving transistor DT is automatically turned off. At this time, the gate-source voltage VGS of the driving transistor DT is VN1-VN3=Vth, and the driving transistor DT is at the off critical point. The gate-source voltage difference VGS of the driving transistor DT is maintained by the compensation capacitor C1.

[0064] In the data writing stage, the switch control line EM(n) of the Nth row controls the switch transistor Td to be closed, the compensation control line REF(n) of the Nth row controls the compensation transistor T2 to be closed, the scan line Scan(n) of the Nth row controls the data writing transistor T1 to be opened, and the reset signal line INI(n) of the Nth row controls the reset transistor Ti to be closed. In this stage, the N1 node is written with the data voltage Vdata, and at the same time, the N3 node is coupled to Vref-Vth+α(Vdata-Vref) under the capacitive coupling, where α=C1 / (C1+C2). In this stage, the voltage of the N1 node changes from Vref to Vdata, and the voltage change value of the N1 node is Vdata-Vref. Under the coupling of the storage capacitor C2 and the compensation capacitor C1, the voltage of the N3 node changes with the voltage change of the N1 node, and the change value is α(Vdata-Vref), so that the voltage of the N3 node is coupled to Vref-Vth+α(Vdata-Vref). At this time, the gate-source voltage VGS of the driving transistor DT=(1-α)(Vdata-Vref)+Vth.

[0065] In the light emitting stage, the switch control line EM(n) of the Nth row controls the switch transistor Td to be opened, the compensation control line REF(n) of the Nth row controls T2 to be closed, the scan line Scan(n) of the Nth row controls the data writing transistor T1 to be closed, and the reset signal line INI(n) of the Nth row controls the reset transistor Ti to be closed. Among them, the driving transistor DT is in a conductive state under the action of VGS in the writing stage, and by opening the switch transistor Td, the driving transistor DT generates a driving current I under the action of VGS. The driving transistor DT and the light emitting element OLED are in series voltage division, and finally the voltage of the N3 node is VSS+VOLED (where VOLED is the voltage division of the light emitting element OLED). Due to the holding effect of the compensation capacitor C1, the voltage difference VGS between the N1 node and the N3 node remains unchanged, so the voltage of the N1 node is coupled to (1-α)(Vdata-Vref)+VSS+VOLED+Vth. At this time, the gate-source voltage VGS of the driving transistor DT=(1-α)(Vdata-Vref)+Vth remains unchanged. In this stage, the driving current on the light emitting element OLED is equal to the current flowing through the driving transistor DT, specifically, the driving current I=(k / 2)(VGS-Vth) 2 =(k / 2)[(1-α)(Vdata-Vref)] 2; wherein k = W-Cox-μeff / L; wherein, W represents the channel width of the driving transistor DT, L represents the channel length of the driving transistor DT, Cox represents the unit area capacitance of the gate dielectric layer of the driving transistor DT, and μeff represents the mobility of the channel region semiconductor material of the driving transistor DT. That is, k is a fixed constant.

[0066] The beneficial effects of the present embodiment are as follows. First, by simplifying the 4T2C current in each sub-pixel into a 3T2C circuit, the design area of the light emitting region of each sub-pixel can be increased, which is suitable for ultra-high PPI (pixel number) products and pixel design in the under-screen camera area. Second, in combination with the mask-free evaporation technology to increase the aperture ratio of the light emitting element, the second plate of the capacitor C2 is connected to the cathode of the light emitting element, which can reduce the layout space of the capacitor in the circuit (compared to the scheme of forming the second plate of the storage capacitor by metal traces) while ensuring the capacity of the storage capacitor, that is, the layout space of the metal traces (such as power supply traces).

[0067] In further embodiments, the compensation of the driving transistor DT can be more sufficient by increasing the on time of the compensation transistor T2 and thus increasing the maintenance time of the compensation stage.

[0068] Compared with the compensation in the prior art (such as Figure 1 ), the compensation is insufficient due to the limitation of the scan timing on the scan line Scan; the present application separately compensates each sub-pixel by the separate compensation transistor T2 and the compensation signal line ref, so that the sub-pixel is not limited by the row scan time, thereby achieving better display uniformity at different refresh rates and improving the application field of the compensation circuit.

[0069] It can be understood that when the scan line and the data line write data voltage to the N-5th row of sub-pixels, the input reset voltage to the Nth row of sub-pixels is started; during the period of writing data voltage to the N-4th to N-1st rows of sub-pixels, the Nth row of sub-pixels is compensated, thereby increasing the compensation time of the Nth row of sub-pixels, so that the Nth row of sub-pixels is sufficiently compensated, thereby being suitable for high refresh rate display panels. In other embodiments, the reset voltage can be input to the Nth row of sub-pixels when the N-6th row of sub-pixels starts to scan, and the Nth row of sub-pixels is compensated when the N-5th to N-1st rows of sub-pixels are scanned, thereby further increasing the compensation time. In addition, in a low refresh rate display panel, a timing can also be reserved, that is, the Nth row of sub-pixels is compensated when the N-1st row of sub-pixels is scanned. This is not limited.

[0070] The application optimizes the pixel circuit architecture, replaces the capacitor C2 between N3 and VDD with the capacitor between N3 and the VSS cathode for a single pixel, and combines the maskless evaporation technology, increases the opening rate and the overlapping area of the anode and the OH, increases the capacity of C2 without affecting the circuit design, thereby stabilizing the voltage of N3 point, and improving the stability of the driving voltage of the OLED device in the compensation stage and the display stage.

[0071] The application further provides a display device including the display panel in any of the above embodiments. Details are not repeated here.

[0072] The application has the beneficial effects that the second plate of the stabilizing capacitor in the driving circuit is connected to the cathode of the light-emitting element, the capacitance of the anode of the light-emitting element and the cathode of the light-emitting element is increased by combining the maskless evaporation technology, and the capacitance of the anode of the light-emitting element and the auxiliary cathode is increased by combining the auxiliary cathode, thereby increasing the capacity of the storage capacitor and improving the stability of the voltage input by the driving circuit to the anode of the light-emitting element.

[0073] The above is only an embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent flow transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A display panel, characterized by, The display panel comprises a plurality of light emitting elements and a driving circuit electrically connected to a pixel anode of each light emitting element; Each light emitting element comprises: The pixel anode; A pixel definition layer covering part of the surface of the pixel anode and exposing part of the surface of the pixel anode to form a pixel opening; An organic light emitting layer arranged on the surface of the pixel anode in the pixel opening; A pixel cathode arranged on the surface of the organic light emitting layer in the pixel opening; An overhang structure arranged on the surface of the pixel definition layer away from the pixel anode, the overhang structure comprising an auxiliary cathode arranged on the pixel definition layer away from the pixel anode and an insulating structure arranged on the surface of the auxiliary cathode away from the pixel definition layer; The driving circuit comprises a voltage stabilizing capacitor for stabilizing the voltage transmitted to the pixel anode, the voltage stabilizing capacitor comprising a first capacitor and a second capacitor; part of the pixel anode and the pixel cathode are arranged opposite to each other to form two plates of the first capacitor; part of the pixel anode extends into the pixel definition layer and is arranged opposite to the auxiliary cathode to form two plates of the second capacitor; The pixel cathode extends to the surface of the pixel definition layer and is connected to the auxiliary cathode on the surface of the pixel definition layer, so that the first capacitor and the second capacitor are connected in communication; The thickness of the pixel anode arranged opposite to the auxiliary cathode is greater than the thickness of the pixel anode arranged opposite to the pixel cathode, the upper surface of the pixel anode at the overlapping position with the auxiliary cathode is higher than the upper surface of the pixel anode at the overlapping position with the pixel cathode, so as to reduce the distance between the pixel anode and the auxiliary cathode and increase the capacity of the second capacitor; Or, the pixel anode arranged opposite to the auxiliary cathode comprises a first anode and a second anode, the first anode and the second anode are arranged in an overlapping manner in the stacking direction; the second anode is arranged on the side of the first anode away from the auxiliary cathode, so as to reduce the distance between the first anode and the auxiliary cathode and increase the capacity of the second capacitor; or, the second anode is arranged on the side of the first anode close to the auxiliary cathode, so as to reduce the distance between the second anode and the auxiliary cathode and increase the capacity of the second capacitor; the second anode is made of conductive material; the pixel anode arranged opposite to the pixel cathode comprises the first anode or the second anode.

2. The display panel of claim 1, wherein, A plurality of light emitting elements are arranged in an array on a planar layer of a driving substrate, the planar layer is provided with a groove at a position corresponding to the pixel opening, part of the pixel anode is arranged in the groove and arranged opposite to the pixel cathode; another part of the pixel anode protrudes above the surface of the groove and is arranged opposite to the auxiliary cathode.

3. A drive circuit as claimed in any one of claims 1 to 2, characterized in that The driving circuit comprises: A driving transistor connected to the pixel anode of each light emitting element; a first driving circuit connected to one end of each of the driving transistors, an input end of the first driving circuit being connected to a data line for receiving a data voltage and transmitting to each of the driving transistors; a second driving circuit connected to input ends of the driving transistors, an input end of the second driving circuit being connected to a power supply line for receiving a power supply voltage and transmitting to the driving transistors; a storage capacitor, a first plate of the storage capacitor being connected to a control end of the driving transistor, and a second plate of the storage capacitor being connected to a pixel anode of the light emitting element; a voltage stabilizing capacitor, a first plate of the voltage stabilizing capacitor being connected to the second plate of the storage capacitor and the pixel anode of the light emitting element, and a second plate of the voltage stabilizing capacitor being connected to a pixel cathode of the light emitting element and the auxiliary cathode.

4. The drive circuit according to claim 3, characterized in that, the first driving circuit comprises a data writing transistor and a compensation transistor connected to the control end of the driving transistor; a control end of the data writing transistor is connected to a scan line, an input end is connected to a data line, and an output end is connected to the control end of the driving transistor for writing a data voltage to the driving transistor; a control end of the compensation transistor is connected to a compensation control line, an input end is connected to a compensation signal line, and an output end is connected to the control end of the driving transistor for writing a compensation voltage containing a threshold voltage to the driving transistor.

5. The drive circuit according to claim 3, characterized by the second driving circuit comprises a switch transistor for controlling the light emitting element to emit light and a reset transistor for resetting the pixel anode of the light emitting element; a control end of the switch transistor is connected to a switch control line, an input end is connected to a power supply line, and an output end is connected to the input end of the driving transistor for controlling the driving transistor to drive the light emitting element to emit light; a control end of the reset transistor is connected to a reset control line, an input end is connected to a reset signal line, and an output end is connected to the input end of the driving transistor for charging the pixel anode of the light emitting element with a reset signal through the driving transistor.

6. A driving method, characterized by, a driving method for driving the driving circuit according to any one of claims 3-5, the driving method comprising: a reset stage, the switch control line of the Nth row controls the switch transistor to be closed, the compensation control line of the Nth row controls the compensation transistor to be closed, the scan line of the Nth row controls the data writing transistor to be closed, the reset signal line of the Nth row controls the reset transistor to be opened, so that the control end of the driving transistor retains the voltage of the last frame and is turned on under the action of the voltage of the last frame, the reset voltage is written to the pixel anode of the light emitting element through the driving transistor, the reset of the light emitting element is realized, and the light emitting element does not emit light; In the compensation stage, the switch transistor is turned on by the switch control line of the Nth row, the compensation transistor is turned on by the compensation control line of the Nth row, the data write transistor is turned off by the scan line of the Nth row, and the reset transistor is turned off by the reset signal line of the Nth row, so that the input end of the drive transistor writes the power supply voltage, the control end of the drive transistor writes the compensation voltage, the drive transistor is controlled to be turned on at the compensation voltage, the power supply voltage is charged into the output end of the drive transistor, until the gate-source voltage of the drive transistor is close to the threshold voltage, the drive transistor is turned off, and the light emitting element does not emit light; In the data write stage, the switch transistor is turned off by the switch control line of the Nth row, the compensation transistor is turned off by the compensation control line of the Nth row, the data write transistor is turned on by the scan line of the Nth row, and the reset transistor is turned off by the reset signal line of the Nth row, so that the control end of the drive transistor writes the data voltage, and the light emitting element does not emit light; In the light emitting stage, the switch transistor is turned on by the switch control line of the Nth row, the compensation transistor is turned off by the compensation control line of the Nth row, the data write transistor is turned off by the scan line of the Nth row, and the reset transistor is turned off by the reset signal line of the Nth row, so that the drive transistor generates a drive current under the action of the data voltage, and drives the light emitting element to emit light.

7. A display device, characterized by comprising: The display device comprises the display panel of any one of claims 1-2.

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