阅读说明：本技术 发光器件及显示面板 (Light emitting device and display panel ) 是由 王睿 鉏文权 徐古胜 饶娉 崔玉青 于 2021-08-30 设计创作，主要内容包括：本发明涉及一种发光器件及显示面板,发光器件包括有机发光层；所述有机发光层包括中间发光部,以及围绕所述中间发光部设置的边缘发光部；所述边缘发光部的厚度大于所述中间发光部的厚度。上述发光器件,利用厚度方向上的空间,使发光器件的边缘区域的厚度大于中间区域的厚度。当中间发光部出现衰减时,由于边缘发光部堆积了更多的有机发光材料,因此边缘发光部仍然具有较大的亮度,从而在不增加发光器件的面积的同时延长了发光器件的使用寿命。(The invention relates to a light-emitting device and a display panel, wherein the light-emitting device comprises an organic light-emitting layer; the organic light emitting layer includes an intermediate light emitting portion, and an edge light emitting portion provided around the intermediate light emitting portion; the thickness of the edge light-emitting part is greater than that of the intermediate light-emitting part. The light-emitting device uses the space in the thickness direction to enable the thickness of the edge area of the light-emitting device to be larger than that of the middle area. When the middle light-emitting part is attenuated, the edge light-emitting part still has larger brightness because more organic light-emitting materials are accumulated, so that the service life of the light-emitting device is prolonged while the area of the light-emitting device is not increased.)

1. A light-emitting device characterized by comprising an organic light-emitting layer;

the organic light emitting layer includes an intermediate light emitting portion, and an edge light emitting portion provided around the intermediate light emitting portion;

the thickness of the edge light-emitting part is greater than that of the intermediate light-emitting part.

2. The light-emitting device according to claim 1, wherein the intermediate light-emitting portion has a top surface that is convex outward.

3. The light-emitting device according to claim 1, further comprising a functional film layer on which the organic light-emitting layer is formed;

the distance from the top surface of the edge light-emitting part to the top surface of the functional film layer is greater than the distance from the top surface of the intermediate light-emitting part to the top surface of the functional film layer.

4. A light-emitting device according to claim 3, wherein a side of the functional film layer facing the organic light-emitting layer is formed with an intermediate convex portion configured to be convex in a direction facing the organic light-emitting layer;

the intermediate light emitting part is correspondingly formed on the intermediate convex part.

5. The light-emitting device according to claim 4, wherein the intermediate protrusion has a first top surface protruding outward in an arc shape.

6. The light-emitting device according to claim 4, wherein the side of the functional film layer facing the organic light-emitting layer is further formed with an edge recess surrounding the middle protrusion, the edge recess being configured to be concave toward a direction away from the organic light-emitting layer;

the edge light-emitting part is correspondingly formed on the edge recess part.

7. The light emitting device of claim 6, wherein the edge recess has a second top surface that is concave inward in an arc shape.

8. The sub-pixel structure of claim 4, wherein the side of the functional film layer facing the organic light emitting layer is further formed with an edge leveling portion surrounding the middle protrusion portion;

the edge light-emitting part is correspondingly formed on the edge flat part.

9. A display panel comprising a first light emitting device, a second light emitting device and a third light emitting device which emit lights of different colors, at least the first light emitting device being the light emitting device according to any one of claims 1 to 8.

10. The display panel according to claim 9, wherein a ratio of areas of the first light-emitting device, the second light-emitting device, and the third light-emitting device is 0.8 to 1.2: 1: 1;

preferably, the emission color of the first light emitting device is blue;

the light emission color of the second light emitting device and the third light emitting device is one of red or green.

Technical Field

The present invention relates to the field of display technologies, and in particular, to a light emitting device and a display panel.

Background

With the development of technologies such as big data, cloud computing, mobile internet and the like, people have entered the intelligent era, and as an important window for man-machine interaction in the intelligent era, a display panel is also undergoing a significant revolution. Organic Light-Emitting Diode (OLED) Display panels have become flat panel Display devices with the most potential for development after thin film transistor Liquid Crystal displays due to their advantages of self-luminescence, wide viewing angle, high contrast, low power consumption, very high response speed, thinness, flexibility, low cost, etc., and have begun to replace conventional Liquid Crystal Displays (LCDs) in flat panel Display fields such as mobile phones, tablet computers, digital cameras, etc.

The OLED display panel comprises a substrate and a light-emitting device layer formed on the substrate, wherein the light-emitting device layer comprises a plurality of light-emitting devices, and the light-emitting devices can emit light rays with certain colors to enable the display panel to display images. However, the light emitting device may be attenuated along with the use of the display panel, and when the light emitting device is attenuated to a certain degree, the display panel cannot meet the normal display requirement, thereby affecting the overall service life of the display panel.

Disclosure of Invention

In view of this, it is necessary to provide a light emitting device and a display panel which can solve the problem of short lifetime of some light emitting devices.

According to an aspect of the present application, there is provided a light emitting device including an organic light emitting layer;

the organic light emitting layer includes an intermediate light emitting portion, and an edge light emitting portion provided around the intermediate light emitting portion;

the thickness of the edge light-emitting part is greater than that of the intermediate light-emitting part.

The light-emitting device uses the space in the thickness direction to enable the thickness of the edge area of the light-emitting device to be larger than that of the middle area. When the middle light-emitting part is attenuated, the edge light-emitting part still has larger brightness because more organic light-emitting materials are accumulated, so that the service life of the light-emitting device is prolonged while the area of the light-emitting device is not increased. And because only the edge area needs to be changed, the excessive increase of the driving voltage of the light-emitting device can not be caused.

In one embodiment, the intermediate light emitting portion has a top surface that is outwardly convex.

In one embodiment, the light emitting device further includes a functional film layer on which the organic light emitting layer is formed;

the distance from the top surface of the edge light-emitting part to the top surface of the functional film layer is greater than the distance from the top surface of the intermediate light-emitting part to the top surface of the functional film layer.

In one embodiment, a side of the functional film layer facing the organic light emitting layer is formed with a middle protrusion portion configured to protrude outward in a direction facing the organic light emitting layer;

the intermediate light emitting part is correspondingly formed on the intermediate convex part.

In one embodiment, the middle protrusion has a first top surface protruding outward in an arc shape.

In one embodiment, the side of the functional film layer facing the organic light-emitting layer is further formed with an edge recess surrounding the middle protrusion, and the edge recess is configured to be concave towards the direction far away from the organic light-emitting layer;

the edge light-emitting part is correspondingly formed on the edge recess part.

In one embodiment, the edge recess has a second top surface concave inward in an arc shape.

In one embodiment, the side of the functional film layer facing the organic light-emitting layer is further formed with an edge leveling part surrounding the middle protrusion part;

the edge light-emitting part is correspondingly formed on the edge flat part.

According to another aspect of the present application, there is provided a display panel including first, second, and third light emitting devices emitting different colors of light, at least the first light emitting device being the light emitting device according to any one of claims 1 to 8.

In one embodiment, a ratio of areas of the first light emitting device, the second light emitting device, and the third light emitting device is 0.8-1.2: 1: 1;

preferably, the emission color of the first light emitting device is blue;

the light emission color of the second light emitting device and the third light emitting device is one of red or green.

In the display panel, the thickness of the edge light-emitting part of the organic light-emitting layer of the first light-emitting device which emits blue light is greater than that of the middle light-emitting part, so that the edge light-emitting part still maintains high brightness when the organic light-emitting material of the middle light-emitting part is attenuated. The arrangement of the edge light emitting part belongs to the expansion in the thickness direction, and the area of the light emitting device in the horizontal direction does not need to be increased, so that the reduction of the resolution of the display panel is avoided, the service life of the display panel is prolonged, and the reduction of the display effect is avoided.

Drawings

Fig. 1 is a partial structural view of a light emitting device according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of functional film layers of the light emitting device shown in fig. 1;

fig. 3 is a partial structural view of a light emitting device according to another embodiment of the present invention;

fig. 4 is a schematic structural view of functional film layers of the light emitting device shown in fig. 3;

fig. 5 is a schematic structural view of a light-emitting device according to still another embodiment of the present invention;

fig. 6 is a schematic structural view of functional film layers of the light emitting device shown in fig. 5;

fig. 7 is a schematic partial structure diagram of a display panel according to an embodiment of the invention.

Description of reference numerals:

10. a light emitting device; 12. a functional film layer; 121. a middle boss; 123. an edge recess; 125. an edge leveling portion; 14. an organic light emitting layer; 141. an intermediate light-emitting section; 143. an edge light emitting section;

20. a first light emitting device; 21; a first hole transport layer; 212. a first intermediate boss; 214. a first edge recess; 23. a first organic light emitting layer; 232. a first intermediate light-emitting section; 234. a first edge light emitting section;

30. a second light emitting device; 32. a second hole transport layer; 34. a second organic light emitting layer;

50. a third light emitting device; 52. a third hole transport layer; 54. a third organic light emitting layer.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

In the present invention, the terms "mounted," "connected," "secured," and the like are to be construed broadly unless otherwise specifically indicated and limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1, a light emitting device according to an embodiment of the present invention is used to emit light to realize a display. Specifically, the light emitting device has a light emitting side and a non-light emitting side which are opposite to each other, and the light emitting device includes an anode, an organic light emitting Layer, a cathode, and may further include other film layers for assisting light emission, for example, in a direction from the non-light emitting side to the light emitting side, the light emitting device includes an anode Layer, a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an organic light emitting Layer, an Electron Transport Layer (ETL), an Electron Injection Layer (EIL), and a cathode Layer, which are stacked.

Wherein the hole injection layer is configured to lower a barrier for injection of holes from the anode, enabling efficient injection of holes from the anode into the organic light emitting layer. The hole transport layer is configured to enable controlled transport of the injected hole in a directional order. The organic light emitting layer may be formed by evaporation using a Fine Metal Mask (FMM) or an Open Mask (Open Mask), and configured to emit light by recombination of electrons and holes. The electron transport layer is configured to enable controlled migration of the injected electrons in an ordered orientation. The electron injection layer is configured to lower a barrier for injecting electrons from the cathode, enabling efficient injection of electrons from the cathode into the organic light emitting layer. In this way, the organic material emits light in accordance with a desired gray scale by utilizing the light emission characteristics of the anode layer and the cathode layer under voltage driving.

Further, the organic light emitting layer of the light emitting device may emit monochromatic light such as blue light, green light, or red light. It is understood that in other embodiments, the organic light emitting layer of the light emitting device can emit other colors, and is not limited herein.

As described in the background art, an organic light emitting material forming an organic light emitting layer is liable to decay after long-term use. In the prior art, in order to prolong the service life of the light emitting device, for example, the area of the light emitting device is increased, but the number of the light emitting devices per unit area of the display panel is reduced, and the resolution of the display panel is reduced.

A first aspect of the present application provides a light emitting device including an organic light emitting layer; the organic light emitting layer includes an intermediate light emitting portion, and an edge light emitting portion disposed around the intermediate light emitting portion; the thickness of the edge light-emitting part is greater than that of the middle light-emitting part. Due to the difference in thickness, the service life of the light emitting device is prolonged while the area of the light emitting device does not need to be increased. Further, the drive current can be reduced with a longer service life than if the entire thickness were uniform.

Referring to fig. 1 and 2, the present application provides a light emitting device 10, where the light emitting device 10 includes a functional film 12 and an organic light emitting layer 14, and the organic light emitting layer 14 may be formed on the functional film 12 by evaporating an organic light emitting material. The organic light emitting layer 14 includes an intermediate light emitting portion 141 and an edge light emitting portion 143 surrounding the intermediate light emitting portion 141, and the thickness of the edge light emitting portion 143 is greater than that of the intermediate light emitting portion 141.

As such, the present application utilizes the space of the light emitting device 10 in the thickness direction to make the thickness of the edge region of the light emitting device 10 greater than that of the middle region, as compared to the prior art, which is directed to increase the area of the light emitting device 10 to extend the lifetime of the light emitting device 10. When the middle light-emitting part 141 is attenuated, the edge light-emitting part 143 has more organic light-emitting materials accumulated, so that the edge light-emitting part 143 still has higher brightness, thereby prolonging the service life of the light-emitting device 10, meanwhile, the area of the edge light-emitting part 143 does not need to be increased, the area can be understood as the orthographic projection area of the organic light-emitting layer 14 on the functional film layer, the resolution of the display panel provided with the display device 10 cannot be influenced, and the problems of color edges, edge jagging and the like are avoided.

Specifically, in some embodiments, the functional film layer 12 is a film layer adjacent to the organic light emitting layer 14, such as a hole transport layer, the organic light emitting layer 14 is formed on the functional film layer 12 by evaporating an organic light emitting material, and the top surface of the edge light emitting part 143 is farther from the top surface of the functional film layer 12 than the top surface of the intermediate light emitting part 121 is farther from the top surface of the functional film layer 12. In other embodiments, the functional film layer 12 may also be an electron blocking layer or other film layer.

With reference to fig. 1 and fig. 2, a middle protrusion 121 and an edge recess 123 are formed on a side of the functional film 12 facing the organic light emitting layer 14, the middle protrusion 121 is configured to protrude outward toward the organic light emitting layer 14, the edge recess 123 surrounds an edge of the middle protrusion 121, and the edge recess 123 is configured to recess inward away from the organic light emitting layer 14.

As such, a portion of the organic light emitting material falling on the intermediate protrusion portion 121 forms the intermediate light emitting portion 141, and the intermediate light emitting portion 141 has a top surface and a first bottom surface that are convex outward in a direction away from the functional film layer 12. Another portion of the organic light emitting material falling on the middle protrusion 121 slides down onto the edge recess 123 by gravity, so that an edge light emitting part 143 surrounding the middle light emitting part 141 is more easily formed, the edge light emitting part 143 having a second bottom surface that is opposite to the protruding direction of the first bottom surface and is inwardly concave.

Preferably, in some embodiments, the middle protrusion 121 has a first top surface that is convex outward and arc-shaped, the edge recess 123 has a second top surface that is concave inward and arc-shaped, the first top surface of the middle protrusion 121 and the second top surface of the edge recess 123 are both smoothly extended, and the second top surface of the edge recess 123 is smoothly transited to the first top surface of the middle protrusion 121.

Thus, the middle light-emitting part 141 on the middle protrusion part 121 has a first bottom surface protruding outward in an arc shape in a direction away from the functional film layer 12, the edge light-emitting part 143 on the edge recess part 123 has a second bottom surface protruding inward in an arc shape, and the first bottom surface of the middle light-emitting part 141 and the second bottom surface of the edge light-emitting part 143 both extend smoothly. Therefore, the luminance of the light emitting device 10 is uniformly changed from the middle to the edge, and a good display effect is obtained.

It will be appreciated that the curvature of the medial lobe 121 is designed according to the process capability of the fabrication. If the curvature of the middle protrusion 121 is too small, the middle protrusion 121 is too smooth, and the organic light emitting material falling on the middle protrusion 121 is not likely to slide down to the edge recess 123, which affects the accumulation of the organic light emitting material in the edge recess 123 and thus the thickness of the edge light emitting part 143. On the other hand, if the curvature of the intermediate convex portion 121 is too large, the intermediate light emitting portion 141 and the edge light emitting portion 143 are layered, and luminance display is not uniform.

It is understood that the specific thickness of the edge light emitting part 143 and its width in the horizontal direction perpendicular to the thickness direction are designed according to the power consumption of the display panel. If the thickness of the edge light-emitting part 143 is too large, the entire thickness of the organic light-emitting layer 14 becomes too thick, and the demand for driving current increases. On the contrary, if the thickness of the edge light emitting portion 143 is too small, the lifetime of the light emitting device 10 cannot be effectively extended.

As shown in fig. 3 and 4, in other embodiments, a side of the functional film layer 12 facing the organic light emitting layer 14 is formed with a middle protrusion 121 and an edge leveling portion 125, the middle protrusion 121 is configured to protrude outward in a direction facing the organic light emitting layer 14, the edge leveling portion 125 surrounds the middle protrusion 121, and the edge leveling portion 125 has a second bottom surface extending in a horizontal direction perpendicular to a thickness direction of the functional film layer 12 and the organic light emitting layer 14.

As such, a portion of the organic light emitting material falling on the intermediate protrusion portion 121 forms the intermediate light emitting portion 141, and the intermediate light emitting portion 141 has a top surface and a first bottom surface that are convex outward in a direction away from the functional film layer 12. Another portion of the organic light emitting material falling on the middle protrusion 121 slides down onto the edge flat part 125 by gravity, thereby forming an edge light emitting part 143 surrounding the middle light emitting part 141, the edge light emitting part 143 having a second bottom surface extending in a horizontal direction.

Referring to fig. 3 and 4, in some embodiments, a middle area of the top surface of the middle protrusion 121 protrudes outward in an arc shape, and an edge of the middle protrusion 121 connected to the edge flat portion 125 extends along a direction perpendicular to the bottom surface of the functional film 12 to connect to the edge flat portion 126, so as to simplify a molding process of the edge concave portion 123 and effectively reduce a processing difficulty of the pixel unit 100.

As shown in fig. 5 and fig. 6, in other embodiments, the middle region of the top surface of the middle protrusion 121 protrudes outward in an arc shape, and the edge of the middle protrusion 121 connected to the edge flat portion 125 extends obliquely along the direction intersecting with the bottom surface of the functional film 12 to connect to the edge flat portion 126, so as to simplify the molding process of the edge concave portion 123 and make the light-dark change of the light emitted by the light emitting device 10 more uniform.

The light-emitting device 10 prolongs the attenuation period of the organic light-emitting layer 14 by increasing the edge thickness of the organic light-emitting layer 14 without increasing the area of the light-emitting device 10, thereby prolonging the service life of a display panel using the light-emitting device 10.

As shown in fig. 7, an embodiment of the present invention further provides a display panel, which includes a substrate and a light emitting device layer formed on the substrate, where the light emitting device layer includes a plurality of light emitting devices, the plurality of light emitting devices are arranged in an array, a part of the light emitting devices are configured to emit blue light, a part of the light emitting devices are configured to emit green light, and a part of the light emitting devices are configured to emit red light. It is understood that the arrangement of the light emitting devices is not limited, in some embodiments, three light emitting devices respectively emitting blue light, green light and red light are in one group, and the three light emitting devices in each group may be arranged in a horizontal parallel manner, a vertical parallel manner or a delta-shaped manner.

As described in the background, the sub-pixels that emit high energy photons are more easily attenuated due to the high energy light that easily causes the organic light emitting material to decay. Since blue light is the highest energy visible light near the uv region, and its wavelength is typically between 400-500 nm, and is shorter but higher than the wavelengths of red and green light, the light emitting device emitting blue light is more prone to decay and the luminance of blue light is more attenuated in the same display panel.

Based on the above situation, in the prior art, the area of the light emitting device emitting blue light is generally increased to reduce the current density of the light emitting device, so as to prolong the service life of the light emitting device, and finally, the service life of the whole display panel is prolonged. On the other hand, however, the greater the number of light emitting devices contained in a unit area of the display panel, the more abundant the details of the image can be represented. As the area of the light emitting devices increases, the number of light emitting devices in a unit area decreases accordingly, so that the resolution of the display panel decreases, and the display quality of the display panel is affected. That is, the conventional method of increasing the light emitting device to extend the lifetime of the display panel comes at the expense of the resolution of the display panel.

Further, as the area of the light emitting device is changed, it is general to arrange in a Pentile type arrangement. However, when an image is actually displayed, a Pentile-arranged light emitting device may "borrow" another color of a light emitting device adjacent thereto to constitute three primary colors to collectively realize white display, which may cause problems of low resolution, color fringing, and edge jagging.

In order to solve the above technical problem, the present application provides a display panel including a first light emitting device 20 emitting blue light, a second light emitting device 30 emitting red light, and a third light emitting device 50 emitting green light, wherein a ratio of an area of the first light emitting device 20 emitting blue light in a horizontal direction to an area of the second light emitting device 30 emitting green light, and the third light emitting device 50 emitting red light is 0.8 to 1.2: 1: 1, preferably 1: 1: 1.

the first light emitting device 20 has the same structure as the light emitting device 10, and includes a first functional film 21 and a first organic light emitting layer 23, and the first organic light emitting layer 23 is formed on the first functional film 21 by depositing an organic light emitting material.

Specifically, the first functional film 21 is a hole transport layer, a side of the first functional film 21 facing the first organic light emitting layer 23 is formed with a first middle protrusion 212 and a first edge recess 214, the first middle protrusion 212 is configured to be convex toward the first organic light emitting layer 23, the first edge recess 214 surrounds an edge of the first middle protrusion 212, and the first edge recess 214 is configured to be concave toward a direction away from the first organic light emitting layer 23.

The first organic light emitting layer 23 includes a first intermediate light emitting portion 232 formed on the first intermediate protruding portion 212 and a first edge light emitting portion 243 surrounding the first intermediate light emitting portion 232, the thickness of the first edge light emitting portion 243 is greater than that of the first intermediate light emitting portion 232, the first intermediate light emitting portion 232 on the first intermediate protruding portion 212 has a first bottom surface protruding outward in an arc shape in a direction away from the first functional film layer 21, the first edge light emitting portion 243 on the first edge light emitting portion 243 has a second bottom surface recessed inward in an arc shape, and the first bottom surface of the first intermediate light emitting portion 232 and the second bottom surface of the first edge light emitting portion 243 are both smoothly extended.

In some embodiments, the second light emitting device 30 includes a second functional film layer 32 and a second organic light emitting layer 34, the second functional film layer 32 is a hole transport layer, and the second organic light emitting layer 34 is formed on a top surface of the second functional film layer 32. Since the second light emitting device 30 emitting green light is not easily attenuated compared to the light emitting device 10 emitting blue light, the top surface of the side of the second functional film 32 facing the second organic light emitting layer 34 is concave towards the direction away from the second organic light emitting layer 34, the second organic light emitting layer 34 is formed on the top surface of the functional film 32 to have a top surface and a bottom surface concave inwards, and the thickness of the second organic light emitting layer 34 is gradually reduced from the center to the edge.

In some embodiments, the third light emitting device 50 includes a third functional film layer 52 and a third organic light emitting layer 54, the third functional film layer 52 is a hole transport layer, and the third organic light emitting layer 54 is formed on a top surface of the third functional film layer 52. Since the second light emitting device 50 emitting red light is not easily attenuated compared to the light emitting device 10 emitting blue light, the top surface of the side of the third functional film 52 facing the third organic light emitting layer 54 is recessed in a direction away from the third organic light emitting layer 54, the third organic light emitting layer 54 is formed on the top surface of the third functional film 52 to have a top surface and a bottom surface recessed inwards, and the thickness of the third organic light emitting layer 54 is gradually reduced from the center to the edge.

Further, the first functional film layer 21 of the light emitting device 20, the second functional film layer 32 of the second light emitting device 30, and the third functional film layer 52 of the third light emitting device 50 are simultaneously molded and integrally provided.

In the pixel unit 100 and the display panel, the thickness of the first edge light-emitting portion 243 of the first organic light-emitting layer 23 of the first light-emitting device 20 emitting blue light is greater than the thickness of the first intermediate light-emitting portion 232, so that the first edge light-emitting portion 243 still maintains high luminance when the organic light-emitting material of the first intermediate light-emitting portion 232 attenuates. Since the arrangement of the first edge light emitting section 243 is an extension in the thickness direction without increasing the area of the first light emitting device 20 in the horizontal direction, the ratio of the area of the first light emitting device 20 emitting blue light in the horizontal direction to the areas of the second light emitting device 30 emitting green light and the third light emitting device 50 emitting red light is 0.8 to 1.2: 1: 1, thereby avoiding the reduction of the resolution of the display panel, prolonging the service life of the display panel and avoiding the reduction of the display effect.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.