Display module and display device

Abstract

The invention provides a display module and a display device. The display module comprises a display panel, a cover plate and more than two optical adhesive layers, the cover plate is arranged on one side of the display panel, the more than two optical adhesive layers are arranged between the display panel and the cover plate in a stacked mode, the more than two optical adhesive layers comprise a first adhesive layer attached to the cover plate and other adhesive layers arranged on the side, opposite to the cover plate, of the first adhesive layer, and the energy storage modulus of the first adhesive layer is lower than the average energy storage modulus of the other adhesive layers. The creep recovery rate of the first adhesive layer is lower than the average creep recovery rate of other adhesive layers. In the application, the storage modulus of the first adhesive layer close to the cover plate is lower than the average storage modulus of other adhesive layers, and the creep recovery rate of the first adhesive layer is lower than the average storage modulus of other adhesive layers, so that the first adhesive layer fully absorbs local stress during curved surface fitting by virtue of the low modulus characteristic, and the problem of edge wrinkles is effectively relieved; and meanwhile, other adhesive layers form stable support with higher average modulus, so that the risk of bubble generation is remarkably reduced.

Description

Technical Field

[0001] This application belongs to the field of display devices, and particularly relates to a display module and a display device. Background Technology

[0002] With the development of display technology, display devices (such as mobile phones, tablets, wearable bracelets, or televisions) have been widely used, and users' requirements for display devices are gradually increasing, with display devices gradually developing towards thinner and lighter designs and full-screen designs. However, this has also led to increased manufacturing difficulty for display devices and higher requirements for manufacturing processes. Summary of the Invention

[0003] This application provides a display module and display device that can improve the yield rate of the display device.

[0004] In a first aspect, embodiments of this application provide a display module, including: a display panel; a cover plate disposed on one side of the display panel; and two or more optical adhesive layers stacked between the display panel and the cover plate; the two or more optical adhesive layers include a first adhesive layer bonded to the cover plate and other adhesive layers disposed on the side of the first adhesive layer facing away from the cover plate, wherein the energy storage modulus of the first adhesive layer is lower than the average energy storage modulus of the other adhesive layers, and the creep recovery rate of the first adhesive layer is lower than the average creep recovery rate of the other adhesive layers.

[0005] Secondly, embodiments of this application provide a display device, which includes a display module in any of the embodiments.

[0006] The display module provided in this application embodiment stacks two or more optical adhesive layers between the display panel and the cover plate. The first adhesive layer near the cover plate has a lower energy storage modulus than the average energy storage modulus of the other adhesive layers, and the creep recovery rate of the first adhesive layer is also lower than the average energy storage modulus of the other adhesive layers. This allows the first adhesive layer to fully absorb the local stress during curved surface bonding due to its low modulus characteristics, effectively alleviating the edge wrinkling problem. At the same time, the other adhesive layers form a stable support with a higher average modulus, suppressing the rebound deformation after the display panel and the back plate are compressed, avoiding the separation of the display panel and the cover plate due to the rebound force, and significantly reducing the risk of bubble formation. Attached Figure Description

[0007] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a display module provided in an embodiment of this application; Figure 2This is a cross-sectional structural diagram of a display module provided in an embodiment of this application; Figure 3 This is a cross-sectional structural diagram of another display module provided in an embodiment of this application; Figure 4 This is a schematic diagram of another display module provided in an embodiment of this application; Figure 5 yes Figure 4 A schematic diagram of a cross-sectional structure at point AA in the middle; Figure 6 yes Figure 4 Another cross-sectional structural diagram at point AA; 100. Display module; 110. Display panel; 120. Cover plate; 130. First adhesive layer; 131. Other adhesive layers; 132. Second adhesive layer; 133. Third adhesive layer; 101. Planar area; 102. Curved surface area; 103. Side sub-area; 104. Corner sub-area. Detailed Implementation

[0009] To make the purpose, technical solution, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the implementation details described in this specification are merely for illustrative purposes and are not intended to limit the scope of this application.

[0010] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0011] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0012] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application). Unless otherwise stated, the test temperature for all parameters mentioned in this application is 25°C and the test pressure is standard atmospheric pressure.

[0013] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments, which can be used in various combinations. The examples listed are merely representative and should not be construed as exhaustive.

[0014] Mobile phone products have evolved from conventional 2.5D products to hyperbolic products to conventional 3D products. Due to its better appearance, the equal depth quad curve is being adopted by more and more products. However, with the increase of compression, the equal depth quad curve has a high proportion of edge wrinkles and bubbles, which affects the mass production of products.

[0015] Regarding the above issues, firstly, please refer to [link / reference needed]. Figures 1 to 6 This application provides a display module 100, including: a display panel 110, a cover plate 120, and two or more optical adhesive layers.

[0016] A cover plate 120 is disposed on one side of the display panel 110. Two or more optical adhesive layers are stacked between the display panel 110 and the cover plate 120. The two or more optical adhesive layers include a first adhesive layer 130 that is bonded to the cover plate 120 and other adhesive layers 131 disposed on the side of the first adhesive layer 130 facing away from the cover plate 120. The energy storage modulus of the first adhesive layer 130 is lower than the average energy storage modulus of the other adhesive layers 131, and the creep recovery rate of the first adhesive layer 130 is lower than the average creep recovery rate of the other adhesive layers 131.

[0017] The display module 100 provided in this application embodiment stacks two or more optical adhesive layers between the display panel 110 and the cover plate 120. The first adhesive layer 130 near the cover plate 120 has a lower energy storage modulus than the average energy storage modulus of the other adhesive layers 131, and the creep recovery rate of the first adhesive layer 130 is lower than the average energy storage modulus of the other adhesive layers 131. This allows the first adhesive layer 130 to fully absorb the local stress during curved surface bonding due to its low modulus characteristics, effectively alleviating the problem of edge wrinkles. At the same time, the other adhesive layers 131 form a stable support with a higher average modulus, suppressing the rebound deformation of the display panel 110 and the back plate after compression, avoiding the separation of the display panel 110 and the cover plate 120 due to the rebound force, and significantly reducing the risk of bubble formation.

[0018] This application adopts an average performance gradient design, which eliminates the need to strictly limit the single-layer performance of other adhesive layers 131. It can flexibly adapt to different curved surface shapes and size requirements. In the manufacturing process, it is easier to achieve performance consistency through thickness weighted control, reduce bonding deviations caused by single-layer performance fluctuations, improve the bonding reliability of multi-layer optical adhesive layers, and reduce the risk of problems such as glue overflow, glue shortage, and delamination caused by local stress concentration or insufficient support. This helps to improve the bonding yield of the display module 100. At the same time, the synergistic effect of multi-layer adhesive layers can enhance the tolerance to external environmental factors, reduce failures caused by adhesive layer creep relaxation or modulus decay during long-term use, further improve the reliability of the display module 100 in blocking water, oxygen, sweat, alkali, grease, etc., and extend the service life of the display device.

[0019] The display module 100 in this embodiment can be configured as a curved structure or a planar structure.

[0020] The display module 100 is used to subsequently form a display device. Depending on the actual needs, the display device may include all the structures in the display module 100, or it may only include some of the structures in the display module 100. Besides the structures included in the display module 100 in the embodiments of this application, the embodiments of this application do not limit other structures included in the display module 100, and those skilled in the art can also set other structures according to actual technical needs.

[0021] The display panel 110 is a functional component in the display module 100 used to achieve the display effect. The display panel 110 typically includes multiple stacked film layers. Optionally, the display panel 110 includes a stacked substrate, a driving circuit layer, an encapsulation layer, a light-emitting device layer, and a touch layer, etc., and the light-emitting structure can be disposed in the light-emitting device layer. Other film layer structures can also be provided in the display panel 110 according to actual technical needs. The specific composition and structure of the display panel 110 are not limited in this application embodiment.

[0022] For example, the substrate can be a flexible polyimide (PI) substrate or a rigid glass substrate; when the display module 100 is a flexible curved screen, a PI substrate is preferred due to its excellent bending resistance; when it is a rigid curved screen, an ultra-thin glass substrate can be used. The driving circuit layer can include multiple thin-film transistors, which can adopt a top-gate or bottom-gate structure; the light-emitting device layer can be an organic electroluminescent layer or a quantum dot light-emitting layer; the encapsulation layer can adopt an inorganic or organic-inorganic composite encapsulation structure to prevent water and oxygen intrusion and extend the life of the light-emitting device; the touch layer can be integrated on the side of the encapsulation layer away from the light-emitting device layer, and can adopt a mutual capacitance or self-capacitive touch structure, realizing the touch function through a metal mesh or indium tin oxide electrode.

[0023] The cover plate 120 is used to protect the display panel 110 while ensuring the clarity and transmittance of the displayed image. The cover plate 120 can be made of aluminosilicate glass or high-hardness polycarbonate, and its surface can be treated with anti-fingerprint (AF) and anti-glare (AG) coatings. Those skilled in the art can choose different materials according to actual technical needs, and the embodiments of this application are not limited thereto.

[0024] For example, the cover plate 120 can be disposed on the light-emitting side of the display panel 110 to protect the display panel 110 from direct exposure to the usage environment and prevent damage to the display panel 110 from user touch operation or foreign object intrusion. In this embodiment, only the relative positional relationship between the cover plate 120 and the display panel 110 is limited. Similarly, those skilled in the art can choose different setting methods according to actual technical needs, and this embodiment does not limit the specific setting.

[0025] Please see Figure 2 and Figure 3 Two or more optical adhesive layers are stacked between the display panel 110 and the cover plate 120. The cover plate 120 and the display panel 110 are bonded together by two or more optical adhesive layers, so that the cover plate 120 and the display panel 110 are tightly bonded, and the structure of the light-emitting side of the display panel 110 is better covered, the light-emitting structure in the light-emitting layer is better protected, and the stress generated during bonding is absorbed.

[0026] In light of the foregoing, it is known that bubbles are prone to appear after the Gaussian curved surface of the display module 100 is bonded to the curved area 102 (especially the corner area). This application reduces the bubble problem by using a gradient performance design with two or more layers of optical adhesive.

[0027] The first adhesive layer 130 has different storage modulus and creep recovery rate than other adhesive layers 131. The storage modulus reflects the material's ability to store elastic deformation energy under periodic external forces. The higher the value, the stronger the adhesive layer's resistance to dynamic deformation and the better its support. The storage modulus can measure the rigidity and support capacity of the adhesive layer. The creep recovery rate refers to the proportion of a material that recovers its initial shape after creep deformation under constant stress and the removal of the external force. The higher the value, the stronger the recovery ability and the less residual deformation. The creep recovery rate can measure the deformation recovery ability of the adhesive layer.

[0028] The first adhesive layer 130 is directly bonded to the backlight side (non-light-emitting side) of the cover plate 120. The first adhesive layer 130 has the characteristics of low energy storage modulus and low creep recovery rate, and is a functional layer for stress release.

[0029] Other adhesive layers 131 are disposed on the side of the first adhesive layer 130 facing away from the cover plate 120, that is, the side close to the display panel 110. They can be designed as 1 layer, 2 layers, 3 layers, 4 layers or more, depending on the size and curvature requirements of the display module 100. Other adhesive layers 131 are functional layers that provide structural support and can improve the energy storage modulus and creep recovery rate.

[0030] In this embodiment, the storage modulus of the first adhesive layer 130 is lower than the average storage modulus of the other adhesive layers 131, and the creep recovery rate of the first adhesive layer 130 is lower than the average creep recovery rate of the other adhesive layers 131. The average storage modulus and average creep recovery rate are both calculated using a thickness-weighted average, i.e.: Average energy storage modulus = (sum of energy storage modulus of each layer × thickness of each layer) / sum of thickness of each layer; Average creep recovery rate = (sum of creep recovery rates of each layer × thickness of each layer) / sum of thickness of each layer.

[0031] This application embodiment can reflect the overall performance of other adhesive layers 131 by limiting the average energy storage modulus and average creep recovery rate of other adhesive layers 131, avoiding the influence of the overall bonding effect on the performance deviation of thin layers, and ensuring that other adhesive layers 131 as a whole have stronger support and shape recovery capabilities, forming a gradient effect of rigidity and flexibility synergy with the first adhesive layer 130.

[0032] The difference in energy storage modulus and creep recovery rate between the first adhesive layer 130 and other adhesive layers 131 can be controlled in various ways, and the embodiments of this application do not limit this.

[0033] Those skilled in the art can set different adhesive materials in the preparation process of the first adhesive layer 130 than those in the preparation process of other adhesive layers 131, thereby adjusting the differences in storage modulus and creep recovery rate by means of material differences. This application does not limit the materials of the first adhesive layer 130 and other adhesive layers 131. For example, the material of the first adhesive layer 130 is a UV-curable acrylic adhesive. The storage modulus and creep recovery rate are adjusted by controlling the type of monomer and the amount of crosslinking agent added. Optionally, the monomer types include isooctyl acrylate and hydroxyethyl acrylate, wherein isooctyl acrylate is a soft monomer and hydroxyethyl acrylate is a hard monomer. The crosslinking agent can be an isocyanate crosslinking agent. The materials of other adhesive layers 131 can be thermosetting optical adhesives or UV-thermal dual-curing optical adhesives. The storage modulus and creep recovery rate are adjusted by increasing the amount of crosslinking agent added or introducing rigid monomers. Optionally, the rigid monomer can be styrene.

[0034] Of course, in other embodiments, the storage modulus and creep recovery rate of the first adhesive layer 130 and the other adhesive layers 131 can be made different by controlling the curing process parameters of the first adhesive layer 130 and the other adhesive layers 131 to be different.

[0035] For example, the display module 100 further includes an encapsulation structure located on at least one side of the display panel 110 in a direction parallel to the plane of the display panel 110, and the encapsulation structure is connected to the cover plate 120 and the optical adhesive layer; the cover plate 120 extends at least partially beyond the display panel 110 in a direction parallel to the plane of the display panel 110, so that the encapsulation structure can be disposed at the position where the cover plate 120 extends beyond the display panel 110.

[0036] In some embodiments, in the direction from the display panel 110 to the cover plate 120, the energy storage modulus of two or more optical adhesive layers decreases, and the creep recovery rate of two or more optical adhesive layers decreases.

[0037] In this embodiment, stress release and structural stability are achieved by controlling the performance gradient of the optical adhesive layer. Specifically, in the direction from the display panel 110 to the cover plate 120 (i.e., from the side closer to the display panel 110 to the side closer to the cover plate 120), the energy storage modulus of two or more optical adhesive layers decreases, and the creep recovery rate of two or more optical adhesive layers also decreases.

[0038] When the curved display module 100, such as a four-curved screen with equal depth, is bonded, uneven stress distribution may occur. If the adhesive layer is not strong enough to support the side near the display panel 110, it may cause the panel to separate from the cover plate 120 and generate air bubbles. On the other hand, the Gaussian area near the corner of the curved surface, especially near the cover plate 120, needs to absorb the local bending stress during bonding. If the adhesive layer is too rigid, it may cause edge wrinkles or cracking of the adhesive layer.

[0039] This embodiment of the application sets decreasing energy storage modulus and decreasing creep recovery rate, adapting to stress requirements layer by layer, so that each layer of optical adhesive undertakes a specific function. Specifically, the adhesive layer near the display panel 110 has high energy storage modulus and high creep recovery rate, suppressing rebound deformation with strong support and quickly recovering short-term bonding stress to avoid residual deformation; the adhesive layer near the cover plate 120 has low energy storage modulus and low creep recovery rate, absorbing corner stress with higher deformation capacity and locking the bonding shape with moderate residual deformation, reducing the risk of long-term relaxation. When there are two or more optical adhesive layers, or three or more layers, an intermediate layer is included. The performance of the intermediate layer is between that of the two layers, which enables the gradual transfer of stress and avoids interface separation caused by abrupt changes in interlayer performance.

[0040] In some embodiments, the creep strain of two or more optical adhesive layers increases in the direction from the display panel 110 to the cover plate 120.

[0041] The first adhesive layer 130 has different creep strains from the other adhesive layers 131. Creep strain is the degree to which a material slowly undergoes plastic deformation over time under constant external force, reflecting the material's ability to undergo irreversible deformation after long-term stress. The difference in creep strain between the first adhesive layer 130 and the other adhesive layers 131 can be controlled in various ways, and the embodiments of this application do not limit this.

[0042] In the direction from the display panel 110 to the cover plate 120, the creep strain of two or more optical adhesive layers shows an increasing trend, that is, the creep strain of the first adhesive layer 130 is higher than the creep strain of the other adhesive layers 131.

[0043] The display module 100 in this embodiment further optimizes the balance between stress absorption and long-term morphological stability of curved surfaces through a gradient design of the creep strain of the optical adhesive layers. Specifically, in the direction from the display panel 110 to the cover plate 120 (i.e., from the side closer to the display panel 110 to the side closer to the cover plate 120), the creep strain of two or more optical adhesive layers shows an increasing trend. By progressively improving the creep deformation capability, each layer of optical adhesive can adapt to the stress environment of its location.

[0044] The stress distribution of the curved display module 100 (such as a four-curved screen with equal depth) exhibits a gradient difference. The side near the display panel 110 needs to withstand the rebound force after the back plate and the panel are compressed. If the creep strain of the adhesive layer is too high, it is easy to cause the support to loosen due to plastic deformation after long-term use, causing the panel and the cover plate 120 to separate and generate bubbles. The side near the cover plate 120 needs to absorb the local bending stress during the bonding of the curved surface (especially the corner area 104). If the creep strain of the adhesive layer is too low, the rigidity is too strong and it cannot deform, which can easily cause edge wrinkles or adhesive layer cracking.

[0045] The creep strain increment design of this application resolves the contradictions of the prior art by matching the deformation capacity layer by layer, so that the adhesive layer near the panel can provide support with low strain, while the adhesive layer near the cover plate 120 can absorb stress with high strain.

[0046] The creep strain increase is not unlimited. The creep strain difference between two adjacent optical adhesive layers needs to be controlled within 2% to 15% to avoid excessive difference leading to interlayer deformation incompatibility and causing interface peeling. Creep strain, storage modulus, and creep recovery rate work together to form a low-modulus, high-strain, low-recovery adhesive layer on the side near the cover plate 120, and a high-modulus, low-strain, high-recovery adhesive layer on the side near the display panel 110, so that each layer can take into account both stress absorption and morphological stability.

[0047] In some embodiments, the thickness of two or more optical adhesive layers decreases in the direction from the display panel 110 to the cover plate 120.

[0048] In the direction from the display panel 110 to the cover plate 120, the creep strain of two or more optical adhesive layers shows an increasing trend, that is, the thickness of the first adhesive layer 130 is higher than the single-layer thickness of the other adhesive layers 131. The first adhesive layer 130 has a different thickness from the other adhesive layers 131.

[0049] This embodiment of the application, through this gradient design, further adapts to the mechanical requirements of different areas of the curved display module 100. By gradually thinning the adhesive layer, the thick adhesive layer near the display panel 110 undertakes the structural support function, while the thin adhesive layer near the cover plate 120 undertakes the stress release function, and at the same time avoids the module becoming bulky due to redundant thickness.

[0050] In this application, the decreasing thickness trend refers to the direction from the display panel 110 to the cover plate 120, where the thickness of each layer of optical adhesive decreases sequentially, i.e., the thickness of the first layer (closer to the panel) > the thickness of the second layer > ... > the thickness of the Nth layer (closer to the cover plate 120), where N≥2.

[0051] The side closest to the display panel 110 needs to resist the compressive rebound force of the back panel and the panel. The adhesive layer needs to be thick enough to provide stable support. If the thickness is too thin, the local pressure may be too high due to insufficient support area, which may cause the adhesive layer to crack or the panel to deform.

[0052] The side near the cover plate 120 needs to absorb the concentrated stress of the curved corner. The adhesive layer needs to have high deformation capacity. An excessively thick adhesive layer will increase the risk of adhesive flow during bonding and is prone to causing the adhesive layer to accumulate in the corner sub-area 104 due to its own weight, resulting in wrinkles.

[0053] In this embodiment, the thickness reduction design of thick support and thin pressure relief not only solves the contradictions of the existing technology, but also reduces the amount of material used and lowers the mass production cost through precise thickness ratio.

[0054] The thickness difference between two adjacent layers of optical adhesive needs to be controlled within the range of 20~50μm. If the difference is too small, the thickness gradient is not obvious, and it is impossible to distinguish between the functions of support and pressure relief; if the difference is too large, it is easy to cause poor flatness of the interlayer interface, resulting in air bubbles or poor adhesion during bonding.

[0055] In some embodiments, the total thickness of two or more optical adhesive layers needs to be controlled between 100 and 250 μm, and the thickness of the adhesive layer near the display panel 110 accounts for 40% to 60% of the total thickness to ensure the dominant role of the support layer; the thickness of the adhesive layer near the cover plate 120 accounts for 15% to 30% of the total thickness to avoid thickness redundancy.

[0056] In some embodiments, please refer to Figures 4 to 6The display module 100 includes a planar area 101 and a curved area 102 located around the planar area 101. The curved area 102 includes side sub-areas 103 distributed along the periphery of the planar area 101 and corner sub-areas 104 located between two adjacent side sub-areas 103. Two or more optical adhesive layers are stacked at least in the corner sub-area 104 to form a stacked structure.

[0057] The planar area 101 is the core display area of ​​the display module 100. It is typically rectangular with a smooth surface, and it experiences uniform compressive stress during bonding, generally without stress concentration. The planar area 101 primarily requires optical transparency for the optical adhesive layer; for example, a light transmittance ≥90%.

[0058] The curved area 102 surrounds the flat area 101, enabling a full-screen appearance. The curved area 102 is structurally divided into two sub-areas: side sub-areas 103 and corner sub-areas 104. The side sub-areas 103 extend along the long or short side of the flat area 101, forming a single-curvature cylindrical surface. During bonding, they bear a certain bending stress, with a single stress direction along the length of the side. The corner sub-areas 104 are located at the intersection of two adjacent side sub-areas 103, such as the four corners of a quad-curved screen. They form a double-curvature Gaussian surface, preferably with the same horizontal and vertical curvature radii. During bonding, the display panel 110 and the back panel are compressed in both directions, resulting in stress superposition, making them high-risk areas for bubbles and wrinkles.

[0059] As described above, the bubble problem in the four-curved screen is concentrated on the Gaussian surface of the corner sub-region 104. If the anti-rebound ability of the optical adhesive layer is insufficient, the rebound force will push the display panel 110 and the cover plate 120 apart, forming bubbles. The bidirectional bending of the corner sub-region 104 will cause local stretching or compression of the optical adhesive layer. If the deformation ability of the adhesive layer is insufficient, wrinkles or cracks are likely to occur, further aggravating the failure risk. In this embodiment, two or more optical adhesive layers are stacked at least in the corner sub-region 104, and the stacked structure must cover the corner sub-region 104. Among them, the energy storage modulus of the first adhesive layer 130 is lower than the average energy storage modulus of the other adhesive layers 131, and the creep recovery rate of the first adhesive layer 130 is lower than the average creep recovery rate of the other adhesive layers 131.

[0060] By stacking two or more optical adhesive layers between the display panel 110 and the cover plate 120, and setting the first adhesive layer 130 near the cover plate 120 to have a lower energy storage modulus than the average energy storage modulus of the other adhesive layers 131, and the creep recovery rate of the first adhesive layer 130 to be lower than the average energy storage modulus of the other adhesive layers 131, the first adhesive layer 130 can fully absorb the local stress during curved surface bonding due to its low modulus characteristics, effectively alleviating the edge wrinkling problem. At the same time, the other adhesive layers 131 form a stable support with a higher average modulus, suppressing the rebound deformation of the display panel 110 and the back plate after compression, avoiding the separation of the display panel 110 and the cover plate 120 due to the rebound force, and significantly reducing the risk of bubble generation.

[0061] Preferably, in the direction from the display panel 110 to the cover plate 120, the stacked structure in the corner sub-area 104 exhibits a performance gradient of decreasing energy storage modulus, increasing creep strain, and decreasing thickness. The supporting capacity of the adhesive layer gradually weakens while the stress absorption capacity gradually increases, ensuring that the rebound force is dispersed layer by layer and the concentrated stress is efficiently absorbed.

[0062] In this embodiment, the boundaries of the other adhesive layers 131 in the corner area 104 are in the same plane as the boundaries of the display panel 110 and the back panel. By applying the adhesive layer first and then cutting the whole thing, it can be ensured that the adhesive layer in the corner area 104 has no boundary misalignment, thus avoiding local stress concentration caused by uneven boundaries.

[0063] In this embodiment of the application, two or more optical adhesive layers can also cover a 5mm to 10mm range around the corner area 104, and the 5mm to 10mm range around the corner area 104 will also have stress, i.e. stress-affected area.

[0064] In this embodiment, the optical adhesive layers in the planar region 101 and the curved region 102 can be the same or different. When the optical adhesive layers in the planar region 101 and the curved region 102 are the same, the two or more optical adhesive layers adopt a completely consistent stacking structure, performance parameters, and material formulation in the planar region 101 and the curved region 102. The number of optical adhesive layers, the energy storage modulus gradient of each layer along the direction from the display panel 110 to the cover plate 120, the creep strain gradient along the direction from the display panel 110 to the cover plate 120, and the thickness gradient along the direction from the display panel 110 to the cover plate 120 are kept consistent in the planar region 101 and the curved region 102, and the boundaries of each optical adhesive layer smoothly transition at the junction of the planar region 101 and the curved region 102.

[0065] This unified setup simplifies the mass production process, eliminating the need to design different coating paths or curing parameters for the planar area 101 and the curved area 102. A single optical adhesive layer can be prepared by coating the entire surface and curing it in one step. For example, by using a slot coating process to simultaneously coat each layer of optical adhesive on the entire area of ​​the display panel 110 or cover plate 120, and then curing it according to a unified curing process, the process time is greatly shortened, and the difficulty of equipment debugging and mass production costs are reduced.

[0066] The uniform optical adhesive layer setting needs to be matched with the structure of the cover plate 120 and the display panel 110. The curved area 102 of the cover plate 120 needs to meet a certain radius of curvature. Optionally, the radius of curvature is controlled at 3~5mm to avoid the optical adhesive layer with uniform parameters not being able to deform sufficiently due to too small curvature.

[0067] Since the stress in the planar region 101 is relatively small, the optical adhesive layer settings for the planar region 101 and the curved region 102 can also be different in this embodiment. For example, the planar region 101 can use a single layer of optical adhesive or a simplified stacking to avoid material waste and module bulkiness caused by full-area stacking.

[0068] In some embodiments, in the direction from the display panel 110 to the cover plate 120, the variation range of the energy storage modulus, creep strain and creep recovery rate of at least two optical adhesive layers in the curved region 102 is greater than the variation range in the planar region 101.

[0069] In this application, the gradient amplitude refers to the difference in performance parameters between two adjacent optical adhesive layers along the direction from the display panel 110 to the cover plate 120, which is used to measure the strength of the performance gradient.

[0070] In the direction from the display panel 110 to the cover plate 120, the energy storage modulus, creep strain, and creep recovery rate of at least two optical adhesive layers in the curved region 102 are all greater than their corresponding values ​​in the planar region 101. That is, the performance of at least two optical adhesive layers differs between the curved region 102 and the planar region 101. This regionally differentiated gradient design is adapted to the stress distribution differences between the planar region 101 and the curved region 102 of the display module 100.

[0071] The planar region 101 is subjected to uniform compressive stress, without bending or stress concentration, and does not require a strong gradient to meet the requirements. An excessively strong performance gradient will lead to material waste and process complexity.

[0072] The curved surface region 102 includes the side sub-region 103 and the corner sub-region 104, which are subject to concentrated stress caused by the Gaussian surface. In particular, the stress value of the corner sub-region 104 is higher than that of the planar region 101, and the stress direction is complex. It is necessary to disperse the stress layer by layer through strong performance gradient. In addition, the high modulus layer resists rebound, the high strain layer absorbs bending, and the high recovery layer avoids relaxation, so as to solve the problems of bubbles and wrinkles in a coordinated manner.

[0073] In some embodiments, in the direction from the display panel 110 to the cover plate 120, the variation range of the energy storage modulus, creep strain and creep recovery rate of at least two optical adhesive layers in the corner sub-region 104 is greater than the variation range in the side sub-region 103.

[0074] In the direction from the display panel 110 to the cover plate 120, the magnitude of change in energy storage modulus, creep strain, and creep recovery rate in the corner sub-region 104 are all greater than the corresponding magnitudes in the side sub-region 103. That is, at least two optical adhesive layers exhibit different performance characteristics between the corner sub-region 104 and the side sub-region 103. This regionally differentiated gradient design is adapted to the stress distribution differences between the corner sub-region 104 and the side sub-region 103 of the display module 100.

[0075] The corner sub-region 104 is a hyperbolic Gaussian surface with bidirectional stress superposition; the side sub-region 103 is a single-curvature cylindrical surface that only bears unidirectional stress. It needs to be adapted to the extreme stress requirements of the corner sub-region 104 through a stronger performance gradient, while avoiding performance redundancy in the side sub-region 103.

[0076] In some embodiments, please refer to Figure 5 Other adhesive layers 131 include a second adhesive layer 132, the energy storage modulus of the first adhesive layer 130 is less than the energy storage modulus of the second adhesive layer 132, and the creep recovery rate of the first adhesive layer 130 is less than the creep recovery rate of the second adhesive layer 132.

[0077] In this embodiment, the other adhesive layer 131 of the display module 100 specifically includes a second adhesive layer 132. That is, the optical adhesive layer as a whole is a double-layer structure including a first adhesive layer 130 and a second adhesive layer 132. Along the direction from the display panel 110 to the cover plate 120, the energy storage modulus of the first adhesive layer 130 is less than the energy storage modulus of the second adhesive layer 132, and the creep recovery rate of the first adhesive layer 130 is less than the creep recovery rate of the second adhesive layer 132.

[0078] The second adhesive layer 132 is located near the display panel 110. As a support layer, it needs to resist the rebound force after the display panel 110 and the back plate are compressed, and avoid the separation of the panel and the cover plate 120 to generate air bubbles. Therefore, it is designed to have a high energy storage modulus and a high creep recovery rate, that is, it has strong rigidity and fast recovery capability.

[0079] The first adhesive layer 130, located near the cover plate 120, serves as a stress relief layer. It needs to absorb the concentrated stress, especially in the corner area 104, during curved surface bonding to avoid edge wrinkles. Therefore, it is set to have a low energy storage modulus and a low creep recovery rate, i.e., it has a high deformation capacity and moderate residual deformation to lock the bonding shape.

[0080] The differentiated design of the double-layer adhesive layer in this application simultaneously adjusts the difference between the energy storage modulus and the creep recovery rate, combining support and pressure relief to reduce the bubble rate and wrinkle rate.

[0081] In some embodiments, the storage modulus of the first adhesive layer 130 is 100~300 kPa, and the storage modulus of the second adhesive layer 132 is 300~1000 kPa; the creep recovery rate of the first adhesive layer 130 is 75%~85%, and the creep recovery rate of the second adhesive layer 132 is 85%~95%.

[0082] The first adhesive layer 130 needs to have high deformation capacity to absorb the concentrated stress at the corner of the curved surface. A low modulus range of 100~300KPa can ensure that the adhesive layer undergoes controllable deformation under stress and avoid wrinkles. If the storage modulus is too small, the adhesive layer is too soft and is prone to glue leakage during bonding due to its own weight. If the storage modulus is too large, the rigidity is too strong and cannot adapt to the bidirectional bending of the Gaussian surface, and stress concentration will still occur.

[0083] Meanwhile, the first adhesive layer 130 needs to allow for moderate residual deformation to lock the curved surface bonding shape. A recovery rate of 75% to 85% can ensure that only a certain amount of deformation remains after bonding, which avoids excessive relaxation leading to air bubbles, and also prevents stress rebound caused by complete recovery. If the creep recovery rate is too small, the residual deformation will be too large, and the adhesive layer will easily accumulate and produce wrinkles. If the creep recovery rate is too large, the recovery ability will be too strong, and the stress during bonding cannot be effectively released, which will still cause the panel and cover plate 120 to separate.

[0084] For example, the energy storage modulus of the first adhesive layer 130 is one of 100 kPa, 120 kPa, 140 kPa, 150 kPa, 160 kPa, 180 kPa, 200 kPa, 220 kPa, 240 kPa, 250 kPa, 260 kPa, 280 kPa and 300 kPa.

[0085] For example, the creep recovery rate of the first adhesive layer 130 is one of 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, and 85%.

[0086] The second adhesive layer 132 needs to resist the rebound force between the display panel 110 and the back plate. A high modulus range of 300~1000KPa can provide stable support and prevent the panel from separating from the cover plate 120. If the energy storage modulus is too small, the support force is insufficient, and the rebound force can easily push the panel to separate and generate air bubbles. If the energy storage modulus is too large, the adhesive layer is too brittle and is prone to cracking due to slight deformation of the panel during bonding.

[0087] Meanwhile, the second adhesive layer 132 needs to quickly recover from the short-term deformation during bonding. A high recovery rate of 85% to 95% can restore more than 90% in a short time, avoiding a decrease in support due to residual deformation. If the recovery rate is too small, the residual deformation will cause the adhesive layer to gradually loosen, resulting in bubbles after long-term use. If the recovery rate is too high, the material cost will increase significantly, reducing the cost-effectiveness.

[0088] For example, the energy storage modulus of the second adhesive layer 132 is one of 300 kPa, 310 kPa, 320 kPa, 330 kPa, 350 kPa, 400 kPa, 450 kPa, 500 kPa, 550 kPa, 600 kPa, 650 kPa, 700 kPa, 750 kPa, 800 kPa, 850 kPa, 900 kPa, 950 kPa and 1000 kPa.

[0089] For example, the creep recovery rate of the second adhesive layer 132 is one of 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and 95%.

[0090] It is understood that in some embodiments, the creep strain of the first adhesive layer 130 is greater than the creep strain of the second adhesive layer 132 in the direction from the display panel 110 to the cover plate 120.

[0091] For example, the creep strain range of the first adhesive layer 130 is 15%~25% (test standard GB / T11546.2-2021, test conditions 23℃±2℃, relative humidity 50%±5%, constant stress 50KPa, creep 24h). The above strain range allows the first adhesive layer 130 to absorb local concentrated stress through controllable deformation when it is bonded to the Gaussian curved surface of the corner area 104. Combined with the high strength formed by its high curing rate (≥ the second adhesive layer 132), wrinkles caused by unreleased stress are avoided. The creep strain range of the second adhesive layer 132 is 5%~10%. Its low strain characteristics, combined with its low curing rate, can provide basic support while reducing relaxation deformation during long-term use. This prevents the display panel 110 from separating from the first adhesive layer 130 due to excessive deformation of the second adhesive layer 132, and further assists the first adhesive layer 130 in resisting the rebound force of the module structure, thus alleviating the bubble problem. In some embodiments, the thickness of the first adhesive layer 130 is 25μm-75μm, and the thickness of the second adhesive layer 132 is 75μm-150μm.

[0092] In this embodiment, by further limiting the thickness and ratio of the two adhesive layers, the optical adhesive layer is adapted to the filling requirements of curved surface bonding, and the stress release and structural support functions are enhanced through the thickness difference.

[0093] The first adhesive layer 130 serves as a stress-relieving layer close to the cover plate 120. It needs to absorb the Gaussian stress in the corner sub-region 104 through its low modulus characteristics. In the direction from the display panel 110 to the cover plate 120, the thickness of the first adhesive layer 130 is 25μm~75μm. It can fill the gap between the cover plate 120 and the second adhesive layer 132 while ensuring the deformation capability. It is also particularly suitable for the thin and light requirements of small and medium-sized curved screens.

[0094] If the thickness is too small, the adhesive layer will be too thin, which will easily lead to uneven coverage during bonding, especially at the Gaussian curved surface of the 120° corner of the cover plate. This can easily result in missed areas or areas without adhesive, causing air bubbles. At the same time, the deformation allowance of an excessively thin adhesive layer is insufficient to fully absorb concentrated stress, and edge wrinkles will still occur. If the thickness is too large, the adhesive layer will increase the risk of adhesive flow during bonding. During the bonding process of the 120° curved surface of the cover plate, the thick adhesive layer is easily squeezed towards the edge due to gravity and pressure, contaminating the display area or the light-shielding layer.

[0095] For example, in the direction from the display panel 110 to the cover plate 120, the thickness of the first adhesive layer 130 is one of 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm and 75μm.

[0096] The second adhesive layer 132 serves as a support layer close to the display panel 110 and needs to resist the rebound force between the back panel and the panel. In the direction from the display panel 110 to the cover plate 120, the thickness of the second adhesive layer 132 is 75μm~150μm. It can disperse the rebound force through a larger support area and form a stable support with a high energy storage modulus. At the same time, due to the large bonding area, the adhesion of the thick adhesive material is stronger, which can reduce the risk of loosening after long-term use.

[0097] If the thickness is too small, the adhesive layer will not provide enough support area, which may cause the display panel 110 to deform due to excessive local pressure, or the small bonding area may lead to insufficient adhesion, causing the panel and cover plate 120 to separate and generate air bubbles. If the thickness is too large, the adhesive layer will be too thick, which will cause the overall thickness of the module to exceed the standard. In addition, the curing shrinkage rate of the thick adhesive material will increase, which may cause internal stress due to uneven shrinkage, resulting in warping of the adhesive layer after bonding and affecting the display effect.

[0098] For example, in the direction from the display panel 110 to the cover plate 120, the thickness of the second adhesive layer 132 is one of 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm and 150μm.

[0099] In this embodiment of the application, the thickness of the two adhesive layers must maintain that the second adhesive layer 132 is greater than or equal to the first adhesive layer 130. For example, the thickness ratio of the second adhesive layer 132 to the first adhesive layer 130 is in the range of 1.5:1 to 3:1. For example, the second adhesive layer is 132 75 μm and the first adhesive layer is 130 50 μm, that is, the thickness ratio is 1.5:1. For example, the second adhesive layer is 132 150 μm and the first adhesive layer is 130 50 μm, that is, the thickness ratio is 1.5:1.

[0100] In some embodiments, such as Figure 6 As shown, the other adhesive layers 131 include a third adhesive layer 133 and a second adhesive layer 132 sequentially disposed along the direction from the display panel 110 to the cover plate 120. The energy storage modulus of the first adhesive layer 130 is less than the energy storage modulus of the second adhesive layer 132 and less than the energy storage modulus of the third adhesive layer 133. The creep recovery rate of the first adhesive layer 130 is less than the creep recovery rate of the second adhesive layer 132 and less than the creep recovery rate of the third adhesive layer 133.

[0101] In this embodiment, the other adhesive layers 131 of the display module 100 specifically include a third adhesive layer 133 and a second adhesive layer 132 arranged sequentially along the direction from the display panel 110 to the cover plate 120. That is, the optical adhesive layer as a whole is a three-layer structure including the third adhesive layer 133 (close to the display panel 110), the second adhesive layer 132, and the first adhesive layer 130 (close to the cover plate 120). Along the direction from the display panel 110 to the cover plate 120, the energy storage modulus of the first adhesive layer 130 is limited to < the energy storage modulus of the second adhesive layer 132 < the energy storage modulus of the third adhesive layer 133, and the creep recovery rate of the first adhesive layer 130 is < the creep recovery rate of the second adhesive layer 132 < the creep recovery rate of the third adhesive layer 133.

[0102] In this embodiment, the third adhesive layer 133, the second adhesive layer 132, and the first adhesive layer 130 are stacked together. The three-layer structure design can realize functional decomposition and gradient transition, so that the optical adhesive layer has the functions of support, transition buffer and pressure relief.

[0103] The third adhesive layer 133 is close to the display panel 110 and serves as a support layer to resist the high rebound force between the display panel 110 and the metal back plate. Therefore, it has the highest energy storage modulus, which means it has strong rigidity. At the same time, it needs to quickly recover from the short-term compression deformation during bonding to avoid support relaxation. Therefore, the creep recovery rate needs to be higher than that of the first adhesive layer 130, but lower than that of the second adhesive layer 132.

[0104] The second adhesive layer 132 is an intermediate transition layer, serving as a stress buffer and gradient connection layer. It is used to connect the high modulus of the third adhesive layer 133 with the low modulus of the first adhesive layer 130, avoiding shear stress caused by abrupt changes in interlayer properties. At the same time, the creep recovery rate needs to be between that of the first and third adhesive layers 133 to achieve a smooth transition in recovery capability. This not only assists the third adhesive layer 133 in transmitting support force, but also works with the first adhesive layer 130 to absorb some bending stress, balancing support and pressure relief.

[0105] The first adhesive layer 130 is close to the cover plate 120 and serves as a "high-efficiency stress relief layer" to absorb the bidirectional Gaussian bending stress in the corner sub-region 104. Therefore, it needs to have the lowest energy storage modulus, i.e., high deformation capacity. At the same time, it needs to allow a moderate residual deformation to lock the surface bonding shape, so the creep recovery rate is the lowest to avoid stress rebound caused by complete recovery.

[0106] In some embodiments, the modulus of the first adhesive layer 130 is 100~200 kPa, the modulus of the second adhesive layer 132 is 200~400 kPa, and the modulus of the third adhesive layer 133 is 400~1000 kPa; the creep recovery rate of the first adhesive layer 130 is 75%~85%, the creep recovery rate of the second adhesive layer 132 is 80%~90%, and the creep recovery rate of the third adhesive layer 133 is 85%~95%.

[0107] In this embodiment, the third adhesive layer 133, the second adhesive layer 132, and the first adhesive layer 130, arranged sequentially along the direction from the display panel 110 to the cover plate 120, exhibit a gradient relationship in terms of performance parameters that decreases layer by layer. By further limiting the range and difference of the modulus and recovery rate of each layer, the functions of support, buffering, and pressure relief are coordinated.

[0108] The first adhesive layer 130 needs to absorb stresses such as the bidirectional bending stress of the Gaussian surface in the corner area 104. A low modulus of 100~200 kPa ensures controllable deformation of the adhesive layer under this stress, avoiding wrinkles; if the storage modulus is too small, the adhesive layer is too soft and is prone to flow due to bonding pressure, contaminating the cover plate 120 or the display area; if the storage modulus is too large, the rigidity is too strong and cannot adapt to the Gaussian surface with a small radius of curvature, stress concentration will still occur.

[0109] Meanwhile, the first adhesive layer 130 needs to allow for moderate residual deformation to lock the curved surface bonding shape and avoid stress rebound. A creep recovery rate of 75% to 85% can ensure that only a certain amount of deformation remains after bonding, which satisfies the pressure relief requirements and does not cause excessive adhesive layer accumulation due to excessive residue. If the creep recovery rate is too small, the residual deformation will be too large, which can easily cause wrinkles in the corner sub-area 104. If the creep recovery rate is too large, the recovery ability is too strong, and the stress during bonding cannot be effectively released, which will still cause the panel and cover plate 120 to separate.

[0110] For example, the energy storage modulus of the first adhesive layer 130 is one of 100 kPa, 110 kPa, 120 kPa, 130 kPa, 140 kPa, 150 kPa, 160 kPa, 170 kPa, 180 kPa, 190 kPa and 200 kPa.

[0111] For example, the creep recovery rate of the first adhesive layer 130 is one of 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, and 85%.

[0112] The second adhesive layer 132 needs to bridge the gap between the high modulus of the third adhesive layer 133 and the low modulus of the first adhesive layer 130 to avoid excessive interlayer shear stress. A medium modulus of 200~400KPa can both assist the third adhesive layer 133 in transmitting support force and absorb some bending stress. If the storage modulus is too small, the buffering capacity will be insufficient, which may cause the first adhesive layer 130 to bear too much rebound force. If the storage modulus is too large, the difference between the modulus of the second and third adhesive layers 133 will be too small, thus losing its transitional significance and failing to disperse stress.

[0113] Meanwhile, the second adhesive layer 132 needs to have moderate recovery capability to coordinate the low recovery of the first adhesive layer 130 and the high recovery of the third adhesive layer 133, avoiding interlayer deformation differences that could lead to interface delamination. A recovery rate of 80% to 90% can quickly recover and absorb a certain amount of bending stress, while also helping the first adhesive layer 130 disperse some of the residual deformation. If the recovery rate is too low, it cannot effectively buffer the deformation and is prone to generating shear stress at the interface with the first adhesive layer 130. If the recovery rate is too high, the difference between the recovery rates of the second and third adhesive layers 133 will be too small, losing its transitional significance and failing to achieve coordinated recovery.

[0114] For example, the energy storage modulus of the second adhesive layer 132 is one of 200 kPa, 220 kPa, 240 kPa, 250 kPa, 260 kPa, 280 kPa, 300 kPa, 320 kPa, 340 kPa, 350 kPa, 360 kPa, 380 kPa and 400 kPa.

[0115] For example, the creep recovery rate of the second adhesive layer 132 is one of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90%.

[0116] The third adhesive layer 133 needs to resist the compressive rebound force between the display panel 110 and the back plate. A high modulus of 400~1000KPa can provide stable support and prevent the panel and cover plate 120 from separating and generating air bubbles. If the modulus is too small, the support force is insufficient and the rebound force can easily push the panel apart. If the modulus is too large, the adhesive layer is too brittle and is prone to cracking due to slight deformation of the panel during bonding, which will affect the reliability of the module.

[0117] Meanwhile, the third adhesive layer 133 needs to quickly recover from the short-term compression deformation during bonding to avoid a decrease in support due to residual deformation. A high recovery rate of 85% to 95% ensures that more than 90% of the deformation can be recovered in a short time, resulting in a small decrease in support after long-term use. If the recovery rate is too low, residual deformation will cause the adhesive layer to gradually loosen, leading to bubble rebound. If the recovery rate is too high, special rebound additives need to be added, which significantly increases material costs and reduces cost-effectiveness.

[0118] For example, the energy storage modulus of the third adhesive layer 133 is one of 400 kPa, 450 kPa, 500 kPa, 550 kPa, 600 kPa, 650 kPa, 700 kPa, 750 kPa, 800 kPa, 850 kPa, 900 kPa, 950 kPa and 1000 kPa.

[0119] For example, the creep recovery rate of the third adhesive layer 133 is one of 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% and 95%.

[0120] It is understood that in some embodiments, along the direction from the display panel 110 to the cover plate 120, the creep strain of the third adhesive layer 133 is less than the creep strain of the second adhesive layer 132 and the creep strain of the first adhesive layer 130.

[0121] The optical adhesive layer of the display module 100 includes a third adhesive layer 133, a second adhesive layer 132 and a first adhesive layer 130 arranged sequentially along the direction from the display panel 110 to the cover plate 120, and the three adhesive layers are at least located in the corner sub-area 104; along the direction from the display panel 110 to the cover plate 120, the creep strain of the optical adhesive layer shows an increasing trend, that is, the creep strain of the third adhesive layer 133 < the creep strain of the second adhesive layer 132 < the creep strain of the first adhesive layer 130.

[0122] For example, the creep strain range of the third adhesive layer 133 is 3% to 8%. As a support layer close to the display panel 110, its low strain characteristics, combined with a high curing rate, resist the compressive rebound force between the display panel 110 and the back plate, preventing the support from loosening due to excessive deformation of the third adhesive layer 133, and providing a stable foundation for the overall structure. The creep strain range of the second adhesive layer 132 is 10% to 18%. As an intermediate transition layer, its medium strain characteristics can connect the low strain of the third adhesive layer 133 with the high strain of the first adhesive layer 130. The buffer layer buffers the stress difference between layers, preventing interface peeling due to sudden strain changes. It also absorbs the bending stress of the corner sub-region 104 and assists in the pressure relief of the first adhesive layer 130. The creep strain range of the first adhesive layer 130 is 20%~30%. As a stress relief layer in contact with the cover plate 120, its high strain characteristics can fully absorb the bidirectional concentrated stress (80~150KPa) of the Gaussian surface of the corner sub-region 104. Combined with the strength formed by its high curing rate, it ensures the deformation capacity and avoids the adhesive layer from breaking, further alleviating the bubble problem.

[0123] In some embodiments, the thickness of the first adhesive layer 130 is 25μm-50μm, the thickness of the second adhesive layer 132 is 50μm-75μm, and the thickness of the third adhesive layer 133 is 75μm-100μm.

[0124] In this embodiment, by further defining the thickness relationship of the three adhesive layers, the optical adhesive layer is adapted to the filling requirements of curved surface bonding, and the stress release, stress buffering and structural support functions are enhanced through the thickness difference.

[0125] For example, in the direction from the display panel 110 to the cover plate 120, the thickness of the first adhesive layer 130 is one of 25μm, 30μm, 35μm, 40μm, 45μm and 50μm.

[0126] For example, in the direction from the display panel 110 to the cover plate 120, the thickness of the second adhesive layer 132 is one of 50μm, 55μm, 60μm, 65μm, 70μm and 75μm.

[0127] For example, in the direction from the display panel 110 to the cover plate 120, the thickness of the second adhesive layer 132 is one of 75μm, 80μm, 85μm, 90μm, 95μm and 100μm.

[0128] Secondly, embodiments of this application provide a display device, including the display module in any of the foregoing embodiments.

[0129] It should be noted that the display device provided in this application embodiment has the beneficial effects of any of the aforementioned display modules. For details, please refer to the foregoing description of the beneficial effects of the display modules. This application embodiment will not repeat the description.

[0130] Example 1: A display module, comprising: Display Panel: A flexible OLED panel with overall dimensions of 144.7mm × 68.8mm. The planar area measures 120mm × 60mm, while the curved area includes four side sub-areas: the long side sub-area is 120mm long with a curvature radius of 5mm; the short side sub-area is 60mm long with a curvature radius of 5mm; and four corner sub-areas (curvature radius 2.5mm, Gaussian curved area approximately 10mm × 10mm). From bottom to top, the panel consists of a PI substrate, an IGZO-TFT driving circuit layer, an OLED light-emitting layer, a SiNx-acrylate-SiNx composite encapsulation layer, and an ITO touch layer. The backplane is made of PET material, and after lamination, the rebound force of the corner sub-areas is approximately 50KPa.

[0131] Cover plate: Aluminosilicate glass cover plate, 0.5mm thick, with an anti-fingerprint coating, light transmittance ≥92%, haze ≤0.2%. The cover plate edge is provided with a black ink light-shielding layer, which extends from the back of the cover plate to the side of the cover plate to block the circuits in the non-display area at the edge and prevent light leakage.

[0132] First adhesive layer: A UV-curable optical adhesive, made of acrylic ester, is used, covering at least four corner sub-areas and an 8mm perimeter side sub-area, with a thickness of 30μm. By adjusting the UV curing process parameters, the curing rate is controlled to 85%, with a cured storage modulus of 230KPa (test standard GB / T35465-2017) and a creep recovery rate of 82% (test standard GB / T11546.2-2021).

[0133] The second adhesive layer is a UV-thermal dual-curing optical adhesive made of epoxy-modified acrylate, completely overlapping the first adhesive layer, with a thickness of 50 μm. It is first pre-cured under UV light (wavelength 365 nm, energy 300 mJ / cm², curing rate 50%), followed by low-temperature thermal curing (temperature 80℃, time 30 min), with a final curing rate controlled at 93%. After curing, the storage modulus is 510 kPa, and the creep recovery rate is 90%. The creep strain of the second adhesive layer is less than that of the first adhesive layer.

[0134] Performance test results Bonding yield: 100 modules were sampled and observed under an optical microscope at 200x magnification after bonding. Only one module had a tiny air bubble with a diameter ≤0.1mm in the corner area, and the yield reached 99%.

[0135] Anti-rebound performance: The rebound force of the back panel in the corner area is measured by a pressure sensor. After bonding, the first adhesive layer can resist a rebound force of 50KPa, and there is no separation between the panel and the cover plate. After being placed in a humid heat environment of 85℃ / 85%RH for 1000 hours, the rebound force resistance still remains ≥45KPa, and there is no bubble rebound.

[0136] High and low temperature reliability: After 1000 temperature cycles in the range of -40℃ to 85℃ (each cycle: low temperature hold for 1 hour → room temperature transition for 0.5 hours → high temperature hold for 1 hour → room temperature transition for 0.5 hours), the module showed no delamination or cracking, the deformation of the optical adhesive layer in the corner sub-area was ≤3%, and the uniformity of light emission of the display panel showed no significant change.

[0137] Example 2 A display module, comprising: The display panel uses a rigid OLED panel with a planar area size of 220mm×160mm and a corner sub-area of ​​a Gaussian curved surface with a curvature radius of 4mm. From bottom to top, the panel consists of a glass substrate, a TFT driving layer, an OLED light-emitting layer, a composite encapsulation layer, and a metal mesh touch layer. The back panel is made of aluminum alloy, and the rebound force of the back panel in the corner area after bonding is about 90KPa.

[0138] The cover is made of high-hardness AG glass, with a thickness of 0.7mm and a light transmittance of ≥91%.

[0139] First adhesive layer: UV-curable acrylic adhesive is used to cover the corner area and the surrounding 12mm side area, with a thickness of 50μm; the curing rate is controlled to 85% by UV irradiation (wavelength 365nm, energy 550mJ / cm²), the storage modulus after curing is 160KPa, the adhesion to the cover plate is ≥90N / 25mm, and the creep recovery rate is 78%.

[0140] The second adhesive layer is a UV-thermal dual-curing epoxy acrylate adhesive, which overlaps with the first adhesive layer and has a thickness of 45μm. It is first pre-cured by UV light and then cured by low-temperature heat, with a curing rate of 88%. After curing, the storage modulus is 320KPa and the creep recovery rate is 85%.

[0141] The third adhesive layer is a thermosetting silicone-modified acrylate adhesive, overlapping the second adhesive layer, with a thickness of 60 μm. It is cured at 100℃ for 40 min, with a curing rate of 93% and a storage modulus of 550 kPa after curing. The creep strain of the third adhesive layer is less than that of the second adhesive layer, and the creep strain of the second adhesive layer is less than that of the first adhesive layer.

[0142] Effect verification Bonding yield: 50 modules were sampled, and no air bubbles were found in the corner areas, resulting in a 100% yield rate. Rebound resistance: The first adhesive layer can resist a backplate rebound force of 90 kPa. After a damp heat test at 85℃ / 85%RH for 1000 hours, the rebound resistance remains ≥85 kPa. High and low temperature reliability: After 1000 cycles at -40℃ to 85℃, the three adhesive layers do not delaminate and the optical performance of the module does not degrade.

[0143] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A display module, characterized in that, include: Display panel; A cover plate is disposed on one side of the display panel; And two or more layers of optical adhesive are stacked between the display panel and the cover plate; The two or more optical adhesive layers include a first adhesive layer that adheres to the cover plate and other adhesive layers disposed on the side of the first adhesive layer facing away from the cover plate. The storage modulus of the first adhesive layer is lower than the average storage modulus of the other adhesive layers, and the creep recovery rate of the first adhesive layer is lower than the average creep recovery rate of the other adhesive layers.

2. The display module according to claim 1, characterized in that, In the direction from the display panel to the cover plate, the energy storage modulus of the two or more optical adhesive layers decreases, and the creep recovery rate of the two or more optical adhesive layers decreases.

3. The display module according to claim 1, characterized in that, In the direction from the display panel to the cover plate, the creep strain of the two or more optical adhesive layers shows an increasing trend.

4. The display module according to claim 1, characterized in that, In the direction from the display panel to the cover plate, the thickness of the two or more optical adhesive layers decreases progressively.

5. The display module according to any one of claims 1-4, characterized in that, The display module includes a planar area and a curved area located around the periphery of the planar area. The curved area includes side sub-areas distributed along the periphery of the planar area and corner sub-areas located between two adjacent side sub-areas. The two or more optical adhesive layers are stacked at least in the corner sub-region to form a stacked structure.

6. The display module according to claim 5, characterized in that, In the direction from the display panel to the cover plate, the variation range of the energy storage modulus, creep strain, and creep recovery rate of the at least two optical adhesive layers in the curved area is greater than that in the planar area.

7. The display module according to claim 5, characterized in that, In the direction from the display panel to the cover plate, the variation range of the energy storage modulus, creep strain and creep recovery rate of the at least two optical adhesive layers in the corner sub-region is greater than that in the side sub-region.

8. The display module according to claim 1, characterized in that, The other adhesive layers include a second adhesive layer, wherein the storage modulus of the first adhesive layer is less than that of the second adhesive layer, and the creep recovery rate of the first adhesive layer is less than that of the second adhesive layer.

9. The display module according to claim 8, characterized in that, The storage modulus of the first adhesive layer is 100~300 kPa, and the storage modulus of the second adhesive layer is 300~1000 kPa; the creep recovery rate of the first adhesive layer is 75%~85%, and the creep recovery rate of the second adhesive layer is 85%~95%.

10. The display module according to claim 8, characterized in that, The thickness of the first adhesive layer is 25μm-75μm, and the thickness of the second adhesive layer is 75μm-150μm.

11. The display module according to claim 1, characterized in that, The other adhesive layers include a third adhesive layer and a second adhesive layer sequentially disposed along the direction from the display panel to the cover plate. The energy storage modulus of the first adhesive layer is less than that of the second adhesive layer and less than that of the third adhesive layer. The creep recovery rate of the first adhesive layer is less than that of the second adhesive layer and less than that of the third adhesive layer.

12. The display module according to claim 11, characterized in that, The modulus of the first adhesive layer is 100~200 kPa, the modulus of the second adhesive layer is 200~400 kPa, and the modulus of the third adhesive layer is 400~1000 kPa; the creep recovery rate of the first adhesive layer is 75%~85%, the creep recovery rate of the second adhesive layer is 80%~90%, and the creep recovery rate of the third adhesive layer is 85%~95%.

13. The display module according to claim 12, characterized in that, The thickness of the first adhesive layer is 25μm-50μm, the thickness of the second adhesive layer is 50μm-75μm, and the thickness of the third adhesive layer is 75μm-100μm.

14. A display device, characterized in that, Includes the display module as described in any one of claims 1-13.

Images