Display device and method for manufacturing a display device

Abstract

A display device and a manufacturing method of a display device are provided. The display device includes a display panel, a lower adhesive layer disposed on the display panel, a first adhesive layer disposed on the lower adhesive layer, a second adhesive layer disposed on the first adhesive layer and having a different surface energy from the first adhesive layer, and an upper adhesive layer disposed on the second adhesive layer, an absolute value of a difference between a surface energy of the lower adhesive layer and a surface energy of the first adhesive layer is smaller than an absolute value of a difference between the surface energy of the lower adhesive layer and a surface energy of the second adhesive layer, and an absolute value of a difference between a surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is smaller than an absolute value of a difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer.

Description

Technical Field

[0001] This invention relates to a display device and a method for manufacturing a display device. More specifically, this invention relates to a display device including an adhesive layer and a method for manufacturing a display device including an adhesive layer. Background Technology

[0002] Flat panel displays are used as alternatives to cathode ray tube displays due to their lightweight and thin profile. Representative examples of flat panel displays include liquid crystal displays and organic light-emitting diode (OLED) displays.

[0003] The display device may include a display panel. Multiple layers (e.g., polarizing layers, windows, etc.) may be disposed on the display panel. An adhesive layer may be disposed between the multiple layers to bond them together. However, since the multiple layers have different surface energies, problems may arise where the multiple layers cannot be effectively bonded.

[0004] Therefore, it is necessary to develop a method to effectively bond the multiple layers. Summary of the Invention

[0005] In view of the above circumstances, the present invention addresses the technical challenges of providing a display device including an adhesive layer and a method for manufacturing such a display device.

[0006] However, the problems to be solved by the present invention are not limited to those mentioned above, and various extensions can be made without departing from the spirit and scope of the present invention.

[0007] An embodiment of the display device for achieving the above-described objectives of the present invention may include: a display panel; a lower adhesive layer disposed on the display panel; a first adhesive layer disposed on the lower adhesive layer; a second adhesive layer disposed on the first adhesive layer and having a surface energy different from that of the first adhesive layer; and an upper adhesive layer disposed on the second adhesive layer, wherein the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the first adhesive layer is less than the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the second adhesive layer, and the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is less than the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer.

[0008] In one embodiment, the lower adhesive layer may include a polarizing layer, and the upper adhesive layer may include a window portion.

[0009] In one embodiment, the lower adhesive layer may include a polarizing layer and a buffer layer disposed on the polarizing layer, and the upper adhesive layer may include a window portion.

[0010] In one embodiment, the minimum thickness of the first adhesive layer and the second adhesive layer may be 5 μm.

[0011] In one embodiment, the thickness ratio of the first adhesive layer to the second adhesive layer may be from 1:19 to 19:1.

[0012] In one embodiment, the first adhesive layer and the second adhesive layer may comprise acrylic-based compositions.

[0013] An embodiment of a method for manufacturing a display device to achieve the above-described objectives of the present invention may include: providing a lower adhesive layer on a display panel; providing a first adhesive composition on the lower adhesive layer to form a first adhesive layer; providing a second adhesive composition on the first adhesive layer to form a second adhesive layer; and providing an upper adhesive layer on the second adhesive layer, wherein the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the first adhesive layer is less than the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the second adhesive layer, and the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is less than the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer.

[0014] In one embodiment, the step of providing the first adhesive composition to form the first adhesive layer may include: providing the first adhesive composition on the lower adhesive layer; and performing an initial curing of the first adhesive composition.

[0015] In one embodiment, the step of providing the second adhesive composition to form the second adhesive layer may include: providing the second adhesive composition on the first adhesive layer; and performing an initial curing of the second adhesive composition.

[0016] In one embodiment, the manufacturing method of the display device may further include a step of performing a secondary curing of the first adhesive layer and the second adhesive layer that have undergone initial curing.

[0017] In one embodiment, the primary curing and the secondary curing may utilize ultraviolet light (UV).

[0018] In one embodiment, the surface of the lower adhesive layer that is in contact with the first adhesive layer may be modified before the first adhesive layer is formed.

[0019] In one embodiment, the method of manufacturing the display device may further include a step of modifying the surface of the upper adhesive layer that is in contact with the second adhesive layer before providing the upper adhesive layer on the second adhesive layer.

[0020] In one embodiment, the method of manufacturing the display device may further include: a step of modifying the surface of the lower adhesive layer in contact with the first adhesive layer before forming the first adhesive layer; and a step of modifying the surface of the upper adhesive layer in contact with the second adhesive layer before providing the upper adhesive layer on the second adhesive layer.

[0021] In one embodiment, the first adhesive layer and the second adhesive layer can be formed by an inkjet printing process.

[0022] In one embodiment, the inkjet printing process may be performed using an ejection device, which may include a first ejection port for ejecting the first adhesive composition and a second ejection port for ejecting the second adhesive composition.

[0023] In one embodiment, the dispensing device may further include a first storage unit connected to the first dispensing outlet and a second storage unit connected to the second dispensing outlet.

[0024] In one embodiment, the viscosity of the first adhesive composition and the viscosity of the second adhesive composition may be from 5 cP to 40 cP.

[0025] In one embodiment, the contact angle between the first adhesive component and the lower adhesive layer may be less than 10 degrees.

[0026] In one embodiment, the contact angle between the second adhesive component and the upper adhesive layer may be less than 10 degrees.

[0027] (Invention Effects)

[0028] According to various embodiments of the present invention, a display device may include: a display panel; a lower adhesive layer disposed on the display panel; a first adhesive layer disposed on the lower adhesive layer; a second adhesive layer disposed on the first adhesive layer and having a surface energy different from that of the first adhesive layer; and an upper adhesive layer disposed on the second adhesive layer, wherein the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the first adhesive layer is less than the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the second adhesive layer, and the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is less than the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer.

[0029] Therefore, compared to using a single adhesive layer to bond the lower and upper adhered layers, the lower and upper adhered layers can be bonded more effectively. Specifically, by reducing the difference in surface energy between the lower adhered layer and the first adhesive layer, the lower adhered layer and the first adhesive layer can be bonded effectively. Furthermore, by reducing the difference in surface energy between the upper adhered layer and the second adhesive layer, the upper adhered layer and the second adhesive layer can be bonded effectively.

[0030] However, the effects of the present invention are not limited to those described above, and various extensions can be made beyond the scope and spirit of the present invention. Attached Figure Description

[0031] Figure 1 This is a cross-sectional view illustrating a display device according to an embodiment of the present invention.

[0032] Figure 2 This shows the section along line I-I'. Figure 1 A cross-sectional view of an embodiment of a display device.

[0033] Figure 3 This shows the section along line I-I'. Figure 1 Cross-sectional views of other embodiments of the display device.

[0034] Figures 4a to 4e This is a diagram illustrating a method of providing a first adhesive layer and a second adhesive layer to manufacture a display device.

[0035] Symbol explanation:

[0036] 1000, 1100: Display device; 110, 610: Display panel;

[0037] 120, 125, 620: Lower adhesive layer; 125a: Polarizing layer;

[0038] 125b: Buffer layer; 130, 630: First adhesive layer;

[0039] 140, 640: Second adhesive layer; 150, 650: Upper adhesive layer;

[0040] 400: Dispensing device; 410: Storage unit;

[0041] 420a: First discharge outlet; 420b: Second discharge outlet;

[0042] 500: Lamp. Detailed Implementation

[0043] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings, and repeated descriptions of the same constituent elements are omitted.

[0044] Figure 1 This is a cross-sectional view illustrating a display device according to an embodiment of the present invention. Figure 2 This shows the section along line I-I'. Figure 1 A cross-sectional view of an embodiment of a display device.

[0045] Reference Figure 1 and Figure 2 The display device 1000 may include a display panel 110, a lower adhesive layer 120, a first adhesive layer 130, a second adhesive layer 140, an upper adhesive layer 150, a driving unit 200, a circuit film 300, a plurality of fan-out wirings 200a, a plurality of transmission wirings 200b, and a plurality of pixels PX.

[0046] The display panel 110 may include a display area DA and a non-display area NDA surrounding the display area DA. The display panel 110 may include the plurality of pixels PX. Each of the plurality of pixels PX may include a first electrode, a light-emitting layer, and a second electrode. The plurality of pixels PX may be arranged integrally in a matrix configuration within the display area DA. However, this is an example; the plurality of pixels PX may be arranged in various configurations within the display area DA. The display device 1000 may display an image in the display area DA via the plurality of pixels PX. The display panel 110 may include an organic light-emitting display panel. However, this is an example; the display panel 110 may include a liquid crystal display panel, an electrophoretic display panel, a plasma display panel, etc.

[0047] The driving unit 200 may be disposed in the non-display area NDA of the display panel 110. The driving unit 200 may be disposed on one side of the display area DA. The driving unit 200 may transmit signals (e.g., data signals, power supply voltage, etc.) to the display area DA via the fan-out wiring 200a. The driving unit 200 may receive signals generated by external devices via the transmission wiring 200b. The driving unit 200 may transmit the signals to the display area DA via the fan-out wiring 200a. Although in Figure 1The illustration shows the driving unit 200 disposed on the non-display area NDA of the display panel 110, but is not limited thereto. For example, the driving unit 200 may be disposed on the circuit film 300. The fan-out wiring 200a may be disposed on the non-display area NDA of the display panel 110. The fan-out wiring 200a may be disposed between the display area DA and the driving unit 200. The fan-out wiring 200a may electrically connect the driving unit 200 disposed on the non-display area NDA and the plurality of pixels PX disposed on the display area DA. The fan-out wiring 200a may include data signal wiring, power supply voltage wiring, etc.

[0048] The lower adhesive layer 120 may be disposed on the display panel 110. In one embodiment, the lower adhesive layer 120 may include a polarizing layer for preventing reflection of external light. The polarizing layer can reduce the reflection of external light, thereby improving the visibility of the display device 1000.

[0049] The first adhesive layer 130 may be disposed on the lower adhesive layer 120. The first adhesive layer 130 may be integrally disposed on the lower adhesive layer 120. The first adhesive layer 130 may be composed of a transparent material. For example, the first adhesive layer 130 may be composed of an optically clear resin (OCR), an optically clear adhesive (OCA), or a combination thereof. The first adhesive layer 130 may include an acrylic composition. For example, the first adhesive layer 130 may include epoxy acrylate resins, polyester acrylate resins, urethane acrylate resins, polybutadiene acrylate resins, silicone acrylate resins, alkyl acrylate resins, etc. However, this is an example, the first adhesive layer 130 may also include an adhesive material.

[0050] In one embodiment, to adjust the surface energy of the first adhesive layer 130, the first adhesive layer 130 may further include a hydrophilic or hydrophobic substance (e.g., a fluoride). The hydrophilic substance can increase the surface energy of the first adhesive layer 130. The hydrophobic substance can decrease the surface energy of the first adhesive layer 130.

[0051] In other embodiments, modified acrylic resins can be used to adjust the surface energy of the first adhesive layer 130. For example, fluorinated acrylic resins can be used to reduce surface energy. The surface energy can be adjusted by regulating the fluorine content of the fluorinated acrylic resin. Furthermore, the acrylic resin may contain hydroxyl groups to increase surface energy. The surface energy can be adjusted by regulating the hydroxyl content of the acrylic resin.

[0052] The surface of the lower adhered layer 120 in contact with the first adhesive layer 130 may be modified. In this case, the surface of the upper adhered layer 150 in contact with the second adhesive layer 140 may not be modified. When such modification is performed, the surface energy of the lower adhered layer 120 in contact with the first adhesive layer 130 may be altered. For example, the modification may be performed by plasma surface treatment. Alternatively, the modification may be performed by corona discharge treatment.

[0053] The second adhesive layer 140 may be disposed on the first adhesive layer 130. The second adhesive layer 140 may be integrally disposed on the first adhesive layer 130. The second adhesive layer 140 may be composed of a transparent material. For example, the second adhesive layer 140 may be composed of an optically transparent resin (OCR), an optically transparent adhesive (OCA), or a combination thereof. The second adhesive layer 140 may include an acrylic composition. For example, the second adhesive layer 140 may include epoxy acrylate resins, polyester acrylate resins, urethane acrylate resins, polybutadiene acrylate resins, silicone acrylate resins, alkyl acrylate resins, etc. However, this is just an example; the second adhesive layer 140 may also include an adhesive material. In one embodiment, to adjust the surface energy, the second adhesive layer 140 may include a hydrophilic or hydrophobic material. The hydrophilic material may increase the surface energy of the second adhesive layer 140. The hydrophobic material can reduce the surface energy of the second adhesive layer 140. In one embodiment, the surface energies of the first adhesive layer 130 and the second adhesive layer 140 may be different.

[0054] The upper adhesive layer 150 may be disposed on the second adhesive layer 140. In one embodiment, the upper adhesive layer 150 may include a window portion. The window portion may be made of a transparent material. For example, the window portion may be made of glass, acrylic, polycarbonate, polyimide, polymethyl methacrylate, or a combination thereof. In one embodiment, the window portion may be a touch screen panel.

[0055] In one embodiment, the surface of the upper adhered layer 150 in contact with the second adhesive layer 140 may be modified. In this case, the surface of the lower adhered layer 120 in contact with the first adhesive layer 130 may not be modified. When modification is performed, the surface energy of the upper adhered layer 150 in contact with the second adhesive layer 140 can be altered. For example, the modification can be performed by plasma surface treatment. Alternatively, the modification can be performed by corona discharge treatment. The first adhesive layer 130, together with the second adhesive layer 140, can bond the lower adhered layer 120 and the upper adhered layer 150.

[0056] In various embodiments of the present invention, the surfaces of the upper adhered layer 150 in contact with the second adhesive layer 140 and the lower adhered layer 120 in contact with the first adhesive layer 130 can be modified. When this modification is performed, the surface energy of the lower adhered layer 120 in contact with the first adhesive layer 130 and the surface energy of the upper adhered layer 150 in contact with the second adhesive layer 140 can be altered. For example, this modification can be performed by the plasma surface treatment. Furthermore, the modification can also be performed by the corona discharge treatment.

[0057] The first adhesive layer 130 and the second adhesive layer 140 can be formed by curing an adhesive composition in a liquid or semi-solid state. In one embodiment, the first adhesive layer 130 and the second adhesive layer 140 can be formed by photocuring. That is, when the adhesive composition, which includes a photocurable substance such as a photoinitiator, is irradiated with light such as ultraviolet light, the adhesive composition can be cured. For example, the adhesive composition can be cured by turning monomers and / or intermediates into polymers.

[0058] Depending on the types of materials comprised in the first adhesive layer 130 and the second adhesive layer 140, the thicknesses of the first adhesive layer 130 and the second adhesive layer 140 may differ. In one embodiment, the thickness of the first adhesive layer 130 may be about 1 to about 19 times the thickness of the second adhesive layer 140. In other embodiments, the thickness of the second adhesive layer 140 may be about 1 to about 19 times the thickness of the first adhesive layer 130. However, preferably, the thicknesses of the first adhesive layer 130 and the second adhesive layer 140 may be the same. In one embodiment, the minimum thickness of the first adhesive layer 130 may be about 5 μm. The minimum thickness of the second adhesive layer 140 may also be about 5 μm.

[0059] The smaller the surface energy difference between the adhesive layer and the adhered layer (e.g., the lower adhered layer 120 and the first adhesive layer 130), the better the adhesion. In one embodiment, the absolute value of the difference between the surface energy of the lower adhered layer 120 and the surface energy of the first adhesive layer 130 may be less than the absolute value of the difference between the surface energy of the lower adhered layer 120 and the surface energy of the second adhesive layer 140, and the absolute value of the difference between the surface energy of the upper adhered layer 150 and the surface energy of the second adhesive layer 140 may be less than the absolute value of the difference between the surface energy of the upper adhered layer 150 and the surface energy of the first adhesive layer 130.

[0060] In this case, compared to using a single adhesive layer to bond the lower adhesive layer 120 and the upper adhesive layer 150, the lower adhesive layer 120 and the upper adhesive layer 150 can be bonded more effectively. That is, by reducing the difference in surface energy between the lower adhesive layer 120 and the first adhesive layer 130, the lower adhesive layer 120 and the first adhesive layer 130 can be bonded effectively. Furthermore, by reducing the difference in surface energy between the upper adhesive layer 150 and the second adhesive layer 140, the upper adhesive layer 150 and the second adhesive layer 140 can be bonded effectively. In one embodiment, by adjusting the surface energy through the modification, the surface energy difference between each adhesive layer and each adhesive layer can be adjusted.

[0061] Figure 3 This shows the section along line I-I'. Figure 1 Cross-sectional views of other embodiments of the display device. Figure 3 The display device 1100 and Figure 2 Compared to the display device 1000, except for the lower adhesive layer 125, it can be used with Figure 2 The display device 1000 is substantially the same. Therefore, the description of the repeated configuration is omitted.

[0062] Reference Figure 1 andFigure 3 The display device 1100 may include the lower adhesive layer 125. The lower adhesive layer 125 may be disposed on the display panel 110. The lower adhesive layer 125 may be formed as a single layer or formed by stacking multiple layers. For example, the lower adhesive layer 125 may include a polarizing layer 125a disposed on the display panel 110. Furthermore, the lower adhesive layer 125 may also include a buffer layer 125b disposed on the polarizing layer 125a. The buffer layer 125b may absorb or disperse impacts applied from the outside. In one embodiment, the buffer layer 125b may include a structure of stacked multiple thin film layers. Thus, the buffer layer 125b may absorb or disperse impacts applied from the outside.

[0063] The first adhesive layer 130 may be disposed on the lower adhesive layer 125. The first adhesive layer 130 may be integrally disposed on the buffer layer 125b. In one embodiment, the surface of the buffer layer 125b in contact with the first adhesive layer 130 may be modified. In other embodiments, the surface of the upper adhesive layer 150 bonded to the second adhesive layer 140 may be modified. In yet another embodiment, the surfaces of the buffer layer 125b in contact with the first adhesive layer 130 and the surfaces of the upper adhesive layer 150 bonded to the second adhesive layer 140 may be modified. For example, the modification may be performed by plasma surface treatment. Furthermore, the modification may also be performed by corona discharge treatment.

[0064] The smaller the surface energy difference between the adhesive layer and the adhered layer (e.g., the upper adhered layer 150 and the second adhesive layer 140), the better the adhesion. In one embodiment, the absolute value of the difference between the surface energy of the buffer layer 125b and the surface energy of the first adhesive layer 130 may be less than the absolute value of the difference between the surface energy of the buffer layer 125b and the surface energy of the second adhesive layer 140, and the absolute value of the difference between the surface energy of the upper adhered layer 150 and the surface energy of the second adhesive layer 140 may be less than the absolute value of the difference between the surface energy of the upper adhered layer 150 and the surface energy of the buffer layer 125b. In this case, the buffer layer 125b and the upper adhered layer 150 can be bonded more effectively than if a single adhesive layer is used to bond the buffer layer 125b and the upper adhered layer 150. That is, by reducing the difference in surface energy between the buffer layer 125b and the first adhesive layer 130, the buffer layer 125b and the first adhesive layer 130 can be bonded more effectively. Furthermore, by reducing the difference in surface energy between the upper adhered layer 150 and the second adhesive layer 140, the upper adhered layer 150 and the second adhesive layer 140 can be effectively bonded. The surface energy difference between each adhesive layer and each adhered layer can be adjusted by modifying the surface energy.

[0065] Figures 4a to 4e This is a diagram illustrating a method of providing a first adhesive layer and a second adhesive layer to manufacture a display device.

[0066] Reference Figure 4a A lower adhesive layer 620 may be provided on the display panel 610. In one embodiment, the lower adhesive layer 620 may include the polarizing layer. In other embodiments, the lower adhesive layer 620 may include the polarizing layer and a buffer layer formed on the polarizing layer.

[0067] A first adhesive composition may be provided on the lower adhesive layer 620 to form a first adhesive layer 630. In one embodiment, the first adhesive composition may be provided by an inkjet printing process. However, this is merely an example; the first adhesive composition may be provided using processes such as inkjet injection, slot dye coating, and slot dye printing. By utilizing the inkjet printing process, the first adhesive composition having various surface energies can be used.

[0068] The first adhesive layer 630 may be composed of a transparent material. For example, the first adhesive layer 630 may be composed of an optically transparent resin (OCR), an optically transparent adhesive (OCA), or a combination thereof. The first adhesive layer 630 may include the photocurable material. In one embodiment, the first adhesive layer 630 may include epoxy acrylate resins, polyester acrylate resins, urethane acrylate resins, polybutadiene acrylate resins, silicone acrylate resins, alkyl acrylate resins, etc. However, this is just an example; the first adhesive layer 630 may also include an adhesive material. In one embodiment, to adjust the surface energy of the first adhesive layer 630, the first adhesive layer 630 may include a hydrophilic material or a hydrophobic material (e.g., a fluoride). The hydrophilic material may increase the surface energy of the first adhesive layer 630. The hydrophobic material may decrease the surface energy of the first adhesive layer 630.

[0069] The dispensing device 400 may provide the first adhesive composition on the lower adhesive layer 620. The dispensing device 400 may include a storage section 410, a first dispensing outlet 420a, and a second dispensing outlet 420b. In one embodiment, the dispensing device 400 may be an apparatus for performing an inkjet printing process. In one embodiment, the dispensing device 400 may provide the first adhesive composition having a first surface energy through the first dispensing outlet 420a. The dispensing device 400 may provide a second adhesive composition having a second surface energy different from the first surface energy through the second dispensing outlet 420b. For this purpose, the storage section 410 may include divided storage spaces. In one embodiment, the storage section 410 may include a first storage section and a second storage section. The first storage section and the second storage section may be connected to the first dispensing outlet 420a and the second dispensing outlet 420b, respectively.

[0070] In one embodiment, the first adhesive composition can be provided onto the lower adhered layer 620 through the first dispensing port 420a to form the first adhesive layer 630. However, this is an example, the first adhesive composition can also be provided onto the lower adhered layer 620 through the second dispensing port 420b to form the first adhesive layer 630. In one embodiment, the viscosity of the first adhesive composition can be from about 5 cP to about 40 cP. However, this is an example, and the viscosity of the first adhesive composition is not limited to this. Furthermore, in one embodiment, the minimum thickness of the first adhesive layer 630 can be about 5 μm. The surface of the lower adhered layer 620 in contact with the first adhesive layer 630 can be modified. For example, the modification can be performed by plasma surface treatment. Alternatively, the modification can be performed by corona discharge treatment.

[0071] Reference Figure 4b The first adhesive layer 630 can be formed by curing the first adhesive composition in a liquid or semi-solid state. In one embodiment, the first adhesive layer 630 can be formed by photocuring. That is, when the first adhesive composition, including the photocurable material such as the photoinitiator, is irradiated with light such as ultraviolet light, the first adhesive composition can be cured. The lamp 500 can irradiate the light to initially cure the first adhesive composition. In one embodiment, the lamp 500 can utilize the ultraviolet light to initially cure the first adhesive composition. In one embodiment, the provision of the first adhesive composition and the initial curing can be performed simultaneously. For example, through the initial curing, the first adhesive composition can be cured by about 50% to about 70%.

[0072] Reference Figure 4cThe dispensing device 400 may provide a second adhesive composition on the first adhesive layer 630 to form a second adhesive layer 640. The second adhesive layer 640 may be composed of a transparent material. For example, the second adhesive layer 640 may be composed of an optically clear resin (OCR), an optically clear adhesive (OCA), or a combination thereof. In one embodiment, the second adhesive composition may include epoxy acrylate resins, polyester acrylate resins, urethane acrylate resins, polybutadiene acrylate resins, silicone acrylate resins, alkyl acrylate resins, etc. However, this is merely an example; the second adhesive layer 640 may also include an adhesive material. In one embodiment, to adjust the surface energy of the second adhesive layer 640, the second adhesive layer 640 may include a hydrophilic or hydrophobic material (e.g., a fluoride). The hydrophilic substance can increase the surface energy of the second adhesive layer 640. The hydrophobic substance can decrease the surface energy of the second adhesive layer 640.

[0073] In one embodiment, when the first adhesive composition is provided through the first dispensing port 420a, the dispensing device 400 can provide the second adhesive composition having the second surface energy on the first adhesive layer 630 through the second dispensing port 420b to form the second adhesive layer 640. In other embodiments, when the first adhesive composition is provided through the second dispensing port 420b, the dispensing device 400 can provide the second adhesive composition having the second surface energy on the first adhesive layer 630 through the first dispensing port 420a to form the second adhesive layer 640. In one embodiment, the viscosity of the second adhesive composition may be from about 5 cP to about 40 cP. However, this is illustrative, and the viscosity of the second adhesive composition is not limited to this. Furthermore, in one embodiment, the minimum thickness of the second adhesive layer 640 may be about 5 μm.

[0074] Reference Figure 4dThe second adhesive layer 640 can be formed by curing a second adhesive composition in a liquid or semi-solid state. In one embodiment, the second adhesive layer 640 can be formed by photocuring. For example, the second adhesive composition may include a photocurable material. In one embodiment, the lamp 500 can irradiate the light to initially cure the second adhesive composition. In one embodiment, the application of the second adhesive composition and the initial curing can be performed simultaneously.

[0075] Furthermore, in one embodiment, after the initial curing of the second adhesive layer 640, a secondary curing of the first adhesive layer 630 and the second adhesive layer 640 may be performed. This secondary curing can be performed by irradiation with light; that is, the secondary curing can be performed using ultraviolet light. For example, through the initial curing, the first adhesive layer 630 and the second adhesive layer 640 can be cured by about 50% to about 70%. Subsequently, through the secondary curing, the first adhesive layer 630 and the second adhesive layer 640 can be cured by about 90% to about 95%. However, this is just an example; through the secondary curing, the first adhesive layer 630 and the second adhesive layer 640 can also be cured by more than 95%.

[0076] Reference Figure 4e An upper adhered layer 650 may be provided on the second adhesive layer 640. The upper adhered layer 650 may include a window portion. The upper adhered layer 650 may be provided on the second adhesive layer 640. In one embodiment, the surface of the upper adhered layer 650 in contact with the second adhesive layer 640 may be modified. For example, the modification may be performed by plasma surface treatment. Alternatively, the modification may be performed by corona discharge treatment.

[0077] The smaller the surface energy difference between the adhesive layer and the adhered layer (e.g., the lower adhered layer 620 and the first adhesive layer 630), the better the adhesion. In one embodiment, the absolute value of the difference between the surface energy of the lower adhered layer 620 and the surface energy of the first adhesive layer 630 may be less than the absolute value of the difference between the surface energy of the lower adhered layer 620 and the surface energy of the second adhesive layer 640, and the absolute value of the difference between the surface energy of the upper adhered layer 650 and the surface energy of the second adhesive layer 640 may be less than the absolute value of the difference between the surface energy of the upper adhered layer 650 and the surface energy of the first adhesive layer 630. In this case, the lower adhered layer 620 and the upper adhered layer 650 can be bonded more effectively than if a single adhesive layer is used to bond the lower adhered layer 620 and the upper adhered layer 650. That is, by reducing the difference in surface energy between the lower adhesive layer 620 and the first adhesive layer 630, the lower adhesive layer 620 and the first adhesive layer 630 can be effectively bonded. Furthermore, by reducing the difference in surface energy between the upper adhesive layer 650 and the second adhesive layer 640, the upper adhesive layer 650 and the second adhesive layer 640 can be effectively bonded. In one embodiment, the surface energy can be adjusted through the modification, thereby adjusting the surface energy difference between each adhesive layer and each adhesive layer.

[0078] Therefore, in one embodiment, the method of manufacturing the display device may modify the surface of the lower adhesive layer 620 that contacts the first adhesive layer 630. In other embodiments, the method of manufacturing the display device may modify the surface of the upper adhesive layer 650 that contacts the second adhesive layer 640. In yet another embodiment, the method of manufacturing the display device may modify the surface of the lower adhesive layer 620 that contacts the first adhesive layer 630, and may also modify the surface of the upper adhesive layer 650 that contacts the second adhesive layer 640.

[0079] According to various embodiments of the present invention, in order to maximize the adhesion between the adhesive layer and the adhered layer, the adhesive layer can be determined based on the contact angle. In one embodiment, the contact angle between the first adhesive component and the lower adhered layer can be less than 10 degrees, and the contact angle between the second adhesive component and the upper adhered layer can be less than 10 degrees. The smaller the contact angle between the adhesive layer and the adhered layer, the smaller the difference in surface energy between the adhesive layer and the adhered layer can be. Thus, the adhesive layer can be determined based on the contact angle between the adhered layer and the adhesive layer.

[0080] By using multiple adhesive layers with different surface energies, adhesive layers and substrates with small differences in surface energy are bonded together, thereby effectively bonding the lower substrate and the upper substrate.

[0081] (Industry availability)

[0082] This invention is applicable to display devices and methods of manufacturing display devices. For example, it is applicable to high-resolution smartphones, portable phones, smart tablets, smartwatches, tablet PCs, vehicle navigation systems, televisions, computer monitors, laptops, etc.

[0083] While the invention has been described above with reference to exemplary embodiments thereof, those skilled in the art should understand that various modifications and alterations may be made to the invention without departing from the spirit and scope of the invention as set forth in the claims.

Claims

1. A display device, comprising: Display panel; The lower part is adhered to and disposed on the display panel; A first adhesive layer is disposed on the lower adhesive layer; A second adhesive layer is disposed on the first adhesive layer and has a different surface energy than the first adhesive layer; as well as The upper adhesive layer is disposed on the second adhesive layer. The absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the first adhesive layer is less than the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the second adhesive layer. The absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is less than the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer. The minimum thickness of the first adhesive layer and the second adhesive layer is 5 μm; The thickness ratio of the first adhesive layer to the second adhesive layer is 1:19 to 19:

1.

2. The display device according to claim 1, wherein, The lower adhesive layer includes a polarizing layer. The upper adhesive layer includes a window portion.

3. The display device according to claim 1, wherein, The lower adhesive layer includes: polarization layer; and A buffer layer is disposed on the polarization layer. The upper adhesive layer includes a window portion.

4. The display device according to claim 1, wherein, The first adhesive layer and the second adhesive layer comprise acrylic compositions.

5. A method for manufacturing a display device, comprising: The steps for providing the lower adhesive layer on the display panel; The step of providing a first adhesive composition on the lower adhesive layer to form a first adhesive layer; The step of providing a second adhesive composition on the first adhesive layer to form a second adhesive layer; as well as The step of providing an upper adhesive layer on the second adhesive layer. The absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the first adhesive layer is less than the absolute value of the difference between the surface energy of the lower adhesive layer and the surface energy of the second adhesive layer. The absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the second adhesive layer is less than the absolute value of the difference between the surface energy of the upper adhesive layer and the surface energy of the first adhesive layer. The minimum thickness of the first adhesive layer and the second adhesive layer is 5 μm; The thickness ratio of the first adhesive layer to the second adhesive layer is 1:19 to 19:

1.

6. The method for manufacturing a display device according to claim 5, wherein, The step of providing the first adhesive composition to form the first adhesive layer includes: The step of providing the first adhesive composition on the lower adhesive layer; and The step of initially curing the first adhesive composition.

7. The method for manufacturing a display device according to claim 6, wherein, The step of providing the second adhesive composition to form the second adhesive layer includes: The step of providing the second adhesive composition on the first adhesive layer; and The step of initially curing the second adhesive composition.

8. The method for manufacturing a display device according to claim 7, further comprising: The step of performing a second curing on the first adhesive layer and the second adhesive layer that have undergone initial curing.

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