Patent Application
20190024469
The disclosure relates to the field of display, and in particular, to a flexible display apparatus and an encapsulation method thereof.
The development of traditional flat panel display device technologies has become increasingly mature, whereas flexible display devices are about to become the mainstream in the display field by virtue of their characteristics of being light & thin, bendable, and impact resistant. Therein, OLEDs (Organic Light Emitting Diodes) have become one of the hot spots researched in the field of flexible display recently due to having the excellent performances of a rapid response speed, a wide viewing angle, high luminance, low power consumption, being self-luminous, and flex resistance, etc.
An OLED device is very sensitive to water vapor and oxygen, and it is prone to decay. An effective encapsulation may prevent immersion of the water vapor and oxygen, prevent the organic materials from ageing, and prolong the lifetime of the OLED device. Nowadays, for a flexible OLED, there are mainly two encapsulation ways, the cover plate encapsulation and the thin film encapsulation (TFE), wherein the cover plate encapsulation uses a prefabricated cover plate for encapsulation, predominantly glass materials and film materials; and the thin film encapsulation mainly adopts a single layer of thin film or multiple layers of thin film for encapsulation.
The inventors have studied deeply the problem with the encapsulation of the flexible display device in the prior art, and found the cause for the appearance of the above-mentioned problem: when the flexible display device is bent, the encapsulating film layer is easily caused to crack along the defect locations, owing to small holes present in the encapsulating film layer and the problem with the stress matching between the encapsulating film layer and a film layer it contacts with. The above-mentioned defect locations refer to the pinholes of the film layer produced at the time of coating, or the micro-cracks due to a poor stress between the film layers, and when the flexible display device is bent, these locations are the points of stress concentration, and are easily affected by an external force to crack.
Based on the above finding of the inventors, the disclosure provides a flexible display apparatus and an encapsulation method thereof, which can solve the problem of easily producing cracks with the existing encapsulating film layer, thereby improving the performance of flex resistance of the flexible display apparatus.
According to an aspect of the disclosure, there is provided a flexible display apparatus comprising: an LED device, and a protective layer arranged on a cathode of the OLED device, the protective layer comprising a water oxygen barrier region and a multi-functional region, the multi-functional region having dual functions of a water oxygen barrier and stress blocking, wherein the thickness of the film layer in the multi-functional region is less than that of the film layer in the water oxygen barrier region, and/or the film texture in the multi-functional region is looser than that in the water oxygen barrier region.
Since the protective layer in the flexible display apparatus according to the disclosure comprises a multi-functional region, when the flexible display apparatus is bent, the stress of the film layer resulting from bending of the film layer gets buffered in the multi-functional region, that is, the existence of the multi-functional region may cut off the expansion path of the stress of the film layer, and thereby may reduce the possibility of producing micro-cracks at the time of bending; meanwhile, the existence of the multi-functional region may further block the expansion of the cracks. As a result, the performance of flex resistance of the device is improved.
In an embodiment of the flexible display apparatus according to the disclosure, the location of the multi-functional region corresponds to a spaced area between adjacent pixels, and the location of the water oxygen barrier region corresponds to a pixel area. Since the film layer corresponding to the multi-functional region varies in texture, thickness and degree of looseness, this may affect the overall optical transmittance of the flexible display apparatus. Therefore, the location of the multi-functional region may correspond to a spaced area between adjacent pixels so as to avoid that the visual effect of the flexible display apparatus is affected.
In an embodiment of the flexible display apparatus according to the disclosure, the protective layer comprises: a first continuously distributed protective layer and a second patterned protective layer, wherein the first protective layer covers the cathodes of all the OLED devices, and the second protective layer is only distributed in the water oxygen barrier region, or preferably, distributed in a corresponding area over a pixel. In the corresponding area over a pixel are arranged the first protective layer and the second protective layer, the film layer is relatively thick and is a water oxygen barrier region; whereas in a spaced area between adjacent pixels is only arranged the first protective layer, namely, the film layer in a spaced area between adjacent pixels is relatively thin, and forms the multi-functional region, such that the stress and cracks within the encapsulating film layer may be blocked here when bent. Generally, the thickness of the first protective layer is 0.05-1 μm.
In an embodiment of the flexible display apparatus according to the disclosure, the texture of one of the first protective layer and the second protective layer is the silicon-nitrogen-based material or the silicon-oxygen-based material, or the textures of both the first protective layer and the second protective layer are the silicon-nitrogen-based material or the silicon-oxygen-based material.
In an embodiment of the flexible display apparatus according to the disclosure, the protective layer comprises: a first film layer with a dense film texture, only distributed in the water oxygen barrier region or especially distributed in a corresponding area over a pixel; and a second film layer with a loose film texture, only distributed in the multi-functional region or especially distributed in a gap between the first film layers. Therein, the film texture of the second film layer is looser than that of the first film layer and formed by coating at different steps, and there is no continuity between the distribution areas of the second film layers, such that expansion of stress may be cut off, s and therefore the stress and cracks within the encapsulating film layer are blocked here. Hence, the distribution area of the second film layer corresponds to a multi-functional region, whereas the film texture of the first film layer is relatively dense, and its distribution area corresponds to a water oxygen barrier region.
In an embodiment of the flexible display apparatus according to the disclosure, the first film layer is of the silicon-nitrogen-based material or the silicon-oxygen-based material with a dense film texture; and the second film layer is of the silicon-nitrogen-based material or the silicon-oxygen-based material with a loose film texture.
According to another aspect of the disclosure, there is provided an encapsulation method for a flexible display apparatus, the encapsulation method comprising: after the completion of a cathode of an OLED device, forming a protective layer comprising a water oxygen barrier region and a multi-functional region overlying the cathode of the OLED device, wherein the multi-functional region has dual functions of a water oxygen barrier and stress blocking, and the thickness of the film layer in the multi-functional region is less than that of the film layer in the water oxygen barrier region, and/or the film texture in the multi-functional region is looser than that in the water oxygen barrier region. The encapsulation method solves the problem of easily producing cracks with the existing encapsulating film layer, and improves the performance of flex resistance of the flexible display apparatus by arranging a multi-functional region in the protective layer to cut off the expansion path of the stress of the film layer and the path for crack expansion.
In an embodiment of the encapsulation method for a flexible display apparatus according to the disclosure, the step of forming a protective layer comprising a water oxygen barrier region and a multi-functional region overlying the cathode of the OLED device may comprise: forming a first protective layer continuously distributed and completely covering the cathode of the OLED device on the cathode of the OLED device; and forming a second protective layer only distributed in a corresponding area over a pixel on the first protective layer, wherein an area where the second protective layer is located constitutes the water oxygen barrier region, whereas an area in which only the first protective layer is distributed (or a corresponding area over a spacing between adjacent pixels) constitutes the multi-functional region. Generally, on the first protective layer, the second protective layer may be formed in a corresponding area over a pixel by using a mask plate.
In an embodiment of the encapsulation method for a flexible display apparatus according to the disclosure, the step of forming a protective layer comprising a water oxygen barrier region and a multi-functional region overlying the cathode of the OLED device may comprise: forming a first film layer with a dense film texture in a corresponding area over a pixel on the cathode of the OLED device; and forming a second film layer with a loose film texture in a gap between the first film layers, wherein an area where the first film layer is located constitutes the water oxygen barrier region, whereas an area where the second film layer is located constitutes the multi-functional region.
In order to more clearly illustrate the technical solutions in embodiments of the disclosure, the appended drawings needing to be used in the embodiments will be introduced briefly in the following. Obviously, the drawings in the following description are only some embodiments of the disclosure, and for those of ordinary skills in the art, other drawings may also be obtained according to these drawings under the premise of not paying out creative work.
10 Substrate; 11 Flexible substrate; 12 OLED device; 13 Protective layer; 14 Protective film; 15 Pixel; 120 Water oxygen barrier region; 130 Multi-functional region; 131 First protective layer; 132 Second protective layer; 134 First film layer; 135 Second film layer.
In the following the technical solutions of the disclosure will be described clearly in detail in connection with the drawings.
As described above,
With respect to the above problem with the encapsulation structure of the flexible display apparatus in the prior art, the inventors have found by research the source of the problem, that is: when the flexible display device is bent, the encapsulating film layer is easily caused to crack along the defect locations, owing to small holes present in the encapsulating film layer and the problem with the stress matching between the encapsulating film layer and a film layer it contacts with. Based on the above research, the stress resulting from the bending of the OLED device 12 may be blocked by arranging a multi-functional region, so as to avoid that the protective layer 13 produces cracks. The basic idea is that, the film layer of the multi-functional region may be arranged with a smaller thickness or a looser film texture, to facilitate that the stress of the film layer resulting from the bending of the film layer gets buffered in the multi-functional region to cut off the expansion path of the stress of the film layer, such that the possibility of micro-cracks of the protective layer 13 caused by the bending of the OLED device 12 may be reduced, and the expansion of the cracks may be blocked, hence improving the performance of flex resistance of the device.
As compared to the prior art, the main innovation point of the encapsulation structure of a flexible display apparatus according to the disclosure lies in that the protective layer 13 as shown in
As regards to the particular construction of the protective layer, for example, the following several ways may be adopted: a first way in which it may be that a single layer film is arranged at the preset location of the multi-functional region 130, and a dual-layer film is arranged in the remaining region (the preset location of the water oxygen barrier region), such that the thickness of the film layer at the preset location of the multi-functional region 130 is relatively small to form the multi-functional region 130, and the remaining region forms the water oxygen barrier region; a second way in which it may be that a first film layer with a relative loose film texture is formed at the preset location of the multi-functional region 130 so as to form the multi-functional region 130, whereas a second film layer which is relative dense is formed in the remaining region (the preset location of the water oxygen barrier region) so as to form the water oxygen barrier region; and a third way in which it may be that a protective film layer is first formed as a whole (e.g., a water oxygen barrier protective layer is formed utilizing an encapsulation approach in the prior art), then the film layer is etched at the preset location of the multi-functional region 130, after which the thickness of the film becomes smaller or the film texture becomes looser at the preset location, thereby forming the multi-functional region 130, whereas other un-etched areas form the water oxygen barrier regions. Of course, when implemented particularly, the protective layer may also be constructed employing any other appropriate methods, and in the procedure of constructing the protective layer, the specific thickness of the film layer or the specific degree of looseness of the film texture in the multi-functional region 130 may be set according to the actual needs (e.g., the requirement for the performance of flex resistance or other factors) and the specific material. In the following, the construction of the protective layer (especially the multi-functional region therein) of the flexible display apparatus according to the disclosure will be described in particular with reference to
As shown in
It may be appreciated that the thinner the thickness of the above first protective layer 131, the better its performance of flex resistance, but its corresponding sealing effect will also drop, and therefore the thickness of the first protective layer 131 should be appropriated to take into account both the sealing effect and the performance of flex resistance. For example, the thickness may be 0.05-1 μM.
The texture of one of the first protective layer 131 and the second protective layer 132 may be the silicon-nitrogen-based material (e.g. silicon nitride) or the silicon-oxygen-based material (e.g., silicon oxide). Or the textures of both the first protective layer 131 and the second protective layer 132 may be the silicon-nitrogen-based material or the silicon-oxygen-based material. Therein, the silicon-nitrogen-based material comprises for example a material containing silicon and oxygen, such as silicon nitride, and the silicon-oxygen-based material comprises for example a material containing silicon and nitrogen, such as silicon oxide.
The embodiment as shown in
In the protective layer in the embodiment as shown in
The first film layer 134 may be of the silicon nitride or the silicon-oxygen-based material with a dense film texture; and the second film layer 135 may be of the silicon nitride or the silicon-oxygen-based material or other porous material with a loose film texture.
In the procedure of preparation, a desired pattern may be obtained by using a mask plate for occlusion or photolithography. In addition, it needs to be noted that, the above-described first film layer 134 and the second film layer 135 may be of the same material, or also may be of different materials. If they are of the same material, the first film layer 134 and the second film layer 135 should be prepared respectively employing different processes (or the same process with different process parameters) to meet different demands for the film textures, and reduce the difference in the film thickness between the water oxygen barrier region 120 and the multi-functional region 130, since an excessively large difference in the film thickness between these two regions will cause adverse affects on subsequent processes for manufacturing the flexible display apparatus.
For the first protective layer 131, the texture and the preparation approach of the protective layer in the prior art may be employed, however, the difference from the prior art lies in that the thickness of the first protective layer 131 is relatively small, in general 0.05-1 μm. In a specific encapsulation procedure of the embodiment, the encapsulation may be done by coating the first protective layer 131 of SiNx/SiO2 on the OLED device by the approach of PECVD (plasma enhanced chemical vapor deposition).
In addition, the second protective layer 132 is only distributed in a corresponding area over a pixel, the requirement for its texture is the same as that of the existing protective layer, and when embodied in particular, the second protective layer 132 may be formed only in a corresponding area over a pixel by way of using a mask plate for occlusion; of course, in addition, the second protective layer 132 may also be formed by way of photolithography.
The texture of one of the first protective layer 131 and the second protective layer 132 described above is the silicon nitride or the silicon-oxygen-based material, or the textures of both the first protective layer 131 and the second protective layer 132 are the silicon nitride or the silicon-oxygen-based material.
The specific encapsulation method for the flexible display apparatus in the embodiment as shown in
At step S201, a layer of SiNx/SiO2 with a dense film texture may be coated on the OLED device 12 by PECVD, and patterning may be done employing a mask plate for occlusion, to occlude a part (corresponding to a multi-functional region 130) which need not be covered with the first film layer 134 using a mask plate. In order to reduce the difference of the film thickness, the part occluded by the mask plate at step S201 is deposited a layer of SiNx/SiO2 with a loose film texture by PECVD, which plays the role of stress blocking and further has the functions of sealing and planarization. The material of the second film layer 135 may also comprise a porous material, e.g., a porous material with the function of moisture absorption.
The above first film layer 134 may be of the silicon nitride or the silicon-oxygen-based material with a dense film texture; and the second film layer 135 may be of the silicon nitride or the silicon-oxygen-based material with a loose film texture. In preparation, a desired pattern may be obtained by using a mask plate for occlusion or photolithography. In addition, it needs to be noted that, the above-described first film layer 134 and the second film layer 135 may be of the same material, or also may be of different materials. If they are of the same material, the first film layer 134 and the second film layer 135 should be prepared respectively employing different processes (or the same process with different process parameters) to meet different demands for the film textures, and reduce the difference in the film thickness.
The encapsulation methods for the flexible display apparatuses in the embodiments as shown in
Except for forming a protective layer having a multi-functional region functioning to block the stress, the flows of preparation and encapsulation of the flexible display apparatuses are identical to the prior art, and the embodiments of the disclosure will not be described in detail again. For example, after the protective layer is produced, a protective film is also needed to be attached for protection to prevent the protective layer from being scratched. The way of attaching may be in the form of hard attached to hard and soft attached to hard, which is roughly the same as the prior art and will not be repeated here.
For a clear description, such a word as first, second, etc. is employed in the disclosure to conduct a category differentiation, however, the word first, second does not limit the disclosure in terms of number, and it is just an illustration of a preferred way. Obvious similar variations or relevant extensions occurring to the skilled in the art according to the disclosure all fall within the protection scope of the invention.
The individual embodiments in the specification are described using a progressive manner, identical or similar parts of the individual embodiments may be referred relative to each other, and each embodiment highlights its difference from other embodiments. Especially for an embodiment of a manufacture method, it is described relatively simply due to it corresponding to a respective apparatus embodiment, and as for its relevant parts reference may be made to the description of the parts of the apparatus embodiment.
What are described above are just specific embodiments of the disclosure, however, the protection scope of the disclosure is not limited thereto, and variations or alternatives easily occurring to any artisan familiar with the technical field within the technical scope disclosed by the disclosure should be encompassed within the protection scope of the disclosure. Therefore, the protection scope of the disclosure should be subject to the protection scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410131612.4 | Apr 2014 | CN | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14135740 | Dec 2013 | US |
| Child | 16141667 | US |
