Display device, electronic device having the same, and manufaturing method of display device

Abstract

The display device comprises a display module, a first adhesive layer, a first protective member, a second adhesive layer, and a support plate. The first adhesive layer is disposed on the display module and includes a first initiator and a second initiator different from the first initiator. The first protective member is disposed on the first adhesive layer. The second adhesive layer is disposed below the display module and includes a third initiator, wherein the third initiator is different from the first initiator and the second initiator. The support plate is disposed below the second adhesive layer.

Description

Technology Field

[0001] The present invention relates to a display device, an electronic device including the same, and a method for manufacturing a display device, and more specifically, to a display device and an electronic device that are foldable and have improved display quality. Background Technology

[0002] Display devices provide information to users by displaying various images within a display area. Generally, display devices display information within an allocated screen.

[0003] Recently, flexible display devices, including bendable flexible display panels, are being developed. Unlike flat panel displays, flexible display devices can be folded, rolled, or bent like paper. Flexible display devices, which can change their shape in various ways, can be carried without being restricted by the existing screen size, thereby improving user convenience.

[0004] However, since thin materials are used to achieve such flexible properties, there are cases where curvature occurs in the display area where the image is displayed. The problem to be solved

[0005] The present invention aims to provide a display device having a low surface roughness in the display area, thereby improving display quality, and an electronic device including the same.

[0006] In addition, the present invention aims to provide a manufacturing method for manufacturing a display device having a low surface roughness in a display area. means of solving the problem

[0007] A display device according to one embodiment of the present invention may include a display module, a first adhesive layer, a first protective member, a second adhesive layer, and a support plate. The first adhesive layer is disposed on the display module and may include a first initiator and a second initiator different from the first initiator. The first protective member may be disposed on the first adhesive layer. The second adhesive layer is disposed below the display module and includes a third initiator, wherein the third initiator may be different from the first initiator and the second initiator. The support plate may be disposed below the second adhesive layer.

[0008] In one embodiment of the present invention, the first initiator may be a substance that initiates a polymerization reaction when heat having a predetermined temperature is applied, and the second initiator may be a substance that initiates a polymerization reaction when light having a predetermined wavelength is applied.

[0009] In one embodiment of the present invention, the third initiator may be a substance that initiates a polymerization reaction when heat having a temperature different from the predetermined temperature is applied.

[0010] In one embodiment of the present invention, the first initiator comprises azobisisobutyronitrile, and the second initiator may comprise at least one of a ketone-based substance and a benzyl ketone-based substance.

[0011] In one embodiment of the present invention, the surface roughness of the lower surface of the first adhesive layer may be greater than the surface roughness of the upper surface of the first adhesive layer.

[0012] In one embodiment of the present invention, the surface roughness of the upper surface of the second adhesive layer may be greater than the surface roughness of the upper surface of the first adhesive layer.

[0013] A display device according to one embodiment of the present invention may further include a third adhesive layer disposed on the first protective member and a second protective member disposed on the third adhesive layer.

[0014] In one embodiment of the present invention, each of the display module, the first adhesive layer, the first protective member, the second adhesive layer, the support plate, the third adhesive layer, and the second protective member can be folded.

[0015] In one embodiment of the present invention, a plurality of folding openings are defined in the support plate, and an adhesive opening that overlaps with the plurality of folding openings may be defined in the second adhesive layer.

[0016] In one embodiment of the present invention, the Kc value of at least one of the second protective member, the third adhesive layer, the first protective member, and the first adhesive layer may be 0.1 or more and 0.2 or less. The Kc value may be a value measured by Phase Measuring Deflectometry (PMD), and may be a curvature value measured for a waveness having a wavelength range of 1.0 mm or more and 3.0 mm or less.

[0017] An electronic device according to one embodiment of the present invention may include a display module, a first adhesive layer, a first protective member, a second adhesive layer, and a support plate. The first adhesive layer is disposed on the display module, and the surface roughness of the lower surface may be greater than the surface roughness of the upper surface facing the lower surface. The first protective member may be disposed on the first adhesive layer. The second adhesive layer may be disposed on the lower part of the display panel. The support plate may be disposed on the lower part of the second adhesive layer.

[0018] In one embodiment of the present invention, the first adhesive layer may include a first initiator and a second initiator different from the first initiator.

[0019] In one embodiment of the present invention, the first initiator may be a substance that initiates a polymerization reaction when heat having a predetermined temperature is applied, and the second initiator may be a substance that initiates a polymerization reaction when light having a predetermined wavelength is applied.

[0020] In one embodiment of the present invention, the first initiator comprises azobisisobutyronitrile, and the second initiator may comprise at least one of a ketone-based substance and a benzyl ketone-based substance.

[0021] An electronic device according to one embodiment of the present invention may further include a third adhesive layer disposed on the first protective member and a second protective member disposed on the third adhesive layer. Each of the display panel, the first adhesive layer, the first protective member, the second adhesive layer, the support plate, the third adhesive layer, and the second protective member may be foldable.

[0022] In one embodiment of the present invention, the Kc value of at least one of the second protective member, the third adhesive layer, the first protective member, and the first adhesive layer may be 0.1 or more and 0.2 or less. The Kc value may be a value measured by Phase Measuring Deflectometry (PMD), and may be a curvature value measured for a waveness having a wavelength range of 1.0 mm or more and 3.0 mm or less.

[0023] A method for manufacturing a display device according to one embodiment of the present invention may include a preparation step, an adhesive layer placement step, a protective member placement step, and a planarization step. In the preparation step, a display module may be prepared. In the adhesive layer placement step, an adhesive layer is placed on the display module, and the creep value of the adhesive layer may be 150% or more and 300% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C. In the protective member placement step, a protective member comprising a transparent material may be placed on the adhesive layer. In the planarization step, a predetermined amount of time may be waited after the protective member placement step.

[0024] A method for manufacturing a display device according to one embodiment of the present invention may further include a photocuring step. In the photocuring step, light having a predetermined wavelength is irradiated onto the upper surface of the protective member, so that the adhesive layer can be cured by the light.

[0025] In one embodiment of the present invention, the creep value of the adhesive layer after the photocuring step may be 80% or more and 130% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C.

[0026] In one embodiment of the present invention, the surface roughness of the lower surface of the adhesive layer may be greater than the surface roughness of the upper surface of the adhesive layer.

[0027] In one embodiment of the present invention, the predetermined time may be 50 minutes or more and 24 hours or less. Effects of the invention

[0028] According to one embodiment of the present invention, a display device having a low surface roughness in the display area and, accordingly, improved display quality and an electronic device including the same can be provided.

[0029] According to one embodiment of the present invention, a display device having a low surface roughness in the display area and, accordingly, improved display quality and an electronic device including the same can be provided. Brief explanation of the drawing

[0030] FIG. 1a illustrates an exemplary view of an electronic device according to one embodiment of the present invention in an unfolded state. FIG. 1b illustrates an exemplary folded electronic device according to one embodiment of the present invention. FIG. 2 is an exemplary exploded view of an electronic device according to one embodiment of the present invention. Figure 3 illustrates an exemplary portion of the cross-section cut along I-I' of Figure 1a. FIG. 4 illustrates an exemplary cross-section of a display module according to one embodiment of the present invention. FIG. 5 illustrates an exemplary cross-section of a display panel (DP) according to one embodiment of the present invention. Figure 6 is an enlarged view of section AA of Figure 3. FIG. 7 is a flowchart of a method for manufacturing a display device according to one embodiment of the present invention. Figures 8a to 8e are drawings corresponding to each step of the method for manufacturing a display device. Figure 9 illustrates the change in roughness of the display area of ​​an electronic device according to the waiting time during the flattening step. FIG. 10 illustrates a display area of ​​an electronic device according to one embodiment of the present invention and a display area of ​​a comparative example. FIG. 11 illustrates an exemplary block diagram of an electronic device according to one embodiment. FIG. 12 illustrates schematic diagrams of electronic devices according to various embodiments. Specific details for implementing the invention

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0032] In the drawings, the proportions and dimensions of the components are exaggerated for the effective illustration of the technical content. “And / or” includes all one or more combinations that the associated components may define.

[0033] Terms such as "include" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] A display device according to one embodiment of the present invention can be applied to various electronic devices. An electronic device according to one embodiment of the present invention includes the display device described above and may further include a module or device having other additional functions in addition to the display device.

[0035] FIG. 1a illustrates an exemplary view of an electronic device (ED) according to one embodiment of the present invention in an unfolded state. FIG. 1b illustrates an exemplary view of an electronic device (ED) according to one embodiment of the present invention in a folded state.

[0036] The first direction (DR1) may be the thickness direction of the electronic device (ED). The second direction (DR2) may be a direction perpendicular to the first direction (DR1). The third direction (DR3) may be a direction perpendicular to the first direction (DR1) and the second direction (DR2).

[0037] Referring to FIG. 1a, the electronic device (ED) may be a device that is activated by an electrical signal. For example, the electronic device (ED) may display an image through a display surface (FS) parallel to a second direction (DR2) and a third direction (DR3). The display surface (FS) of the electronic device (ED) may include a display area (DA) and a non-display area (NDA). The non-display area (NDA) may surround the display area (DA).

[0038] Referring to FIGS. 1a and 1b, the electronic device (ED) can be folded with respect to a folding axis (FX) that extends in a direction parallel to the second direction (DR2).

[0039] In this specification, "in-folding" means that the electronic device (ED) is folded so that the display surface (FS) is not exposed to the outside, and "out-folding" means that the electronic device (ED) is folded so that the display surface (FS) is exposed to the outside. Although the electronic device (ED) is illustrated as being in-folded in FIG. 1b, the present invention is not limited thereto. In one embodiment of the present invention, the electronic device (ED) may be in-folded or out-folded. In another embodiment of the present invention, the electronic device (ED) may be both in-folded and out-folded.

[0040] In FIGS. 1a and 1b, the electronic device (ED) is illustrated as a smartphone, but the electronic device (ED) of the present invention is not limited thereto. In other embodiments of the present invention, the electronic device (ED) may include at least one of a large flexible display and a medium-to-small flexible display. For example, the large flexible display may include a television, a monitor, and an electronic display board. The medium-to-small flexible display may include a tablet, a display embedded in a home appliance, a smart watch, and a smartphone.

[0041] FIG. 2 illustrates an exemplary exploded view of an electronic device (ED) according to one embodiment of the present invention. FIG. 3 illustrates an exemplary part of a cross-section cut along I-I' of FIG. 1a.

[0042] Referring to FIGS. 2 and 3, an electronic device (ED) according to one embodiment of the present invention may include a window module (WM), a display module (DM), a support plate (PT), a cover member (CM), digitizers (DGT1, DGT2), and metal layers (ML1, ML2).

[0043] The window module (WM) and the display module (DM) can be bonded to each other by a first adhesive layer (AL1). The display module (DM) and the support plate (PT) can be bonded to each other by a second adhesive layer (AL2). An adhesive opening (OP-A) may be defined in the second adhesive layer (AL2). The first adhesive layer (AL1) and the second adhesive layer (AL2) may include a pressure-sensitive adhesive (PSA). However, they are not limited thereto, and the first adhesive layer (AL1) and the second adhesive layer (AL2) may include an optically clear adhesive (OCA) or an optically clear resin (OCR).

[0044] A window module (WM) may be positioned on top of a display module (DM) to define the appearance of an electronic device (ED) and protect the display module (DM). The window module (WM) may include a flexible material. Thus, when the electronic device (ED) is folded along a folding axis (FX, see FIG. 1a), the window module (WM) may also bend together.

[0045] The window module (WM) may include a first protective member (PCM1), a third adhesive layer (AL3), and a second protective member (PCM2).

[0046] The first protective member (PCM1) may include a transparent material. Accordingly, light emitted from the display module (DM) can pass through the first protective member (PCM1). For example, the first protective member (PCM1) may include at least one of a glass substrate and a synthetic resin film. The synthetic resin film may include at least one of a polyimide (PI) film and a polyethylene terephthalate (PET). Additionally, the first protective member (PCM1) may include an elastomer.

[0047] In one embodiment of the present invention, the thickness of the first protective member (PCM1) may be 15 μm or more and 100 μm or less. Preferably, the thickness of the first protective member (PCM1) may be 16 μm or more and 85 μm or less. If the thickness of the first protective member (PCM1) is less than 16 μm, it may not effectively protect the components disposed below the first protective member (PCM1). If the thickness of the first protective member (PCM1) exceeds 85 μm, the folding or bending characteristics of the electronic device (ED) may be degraded due to the thick thickness of the first protective member (PCM1).

[0048] In one embodiment of the present invention, the first protective member (PCM1) may be a plurality of synthetic resin films bonded together with an adhesive. In another embodiment of the present invention, the first protective member (PCM1) may be a glass substrate bonded together with at least one synthetic resin film with an adhesive.

[0049] The third adhesive layer (AL3) is disposed between the second protective member (PCM2) and the first protective member (PCM1) to bond the second protective member (PCM2) and the first protective member (PCM1) together.

[0050] The second protective member (PCM2) is placed on the first protective member (PCM1) and protects the first protective member (PCM1) and the functional layer placed below the first protective member (PCM1) against externally applied pressure, thereby preventing deformation of the display module (DM).

[0051] The second protective member (PCM2) may include a plastic material having flexibility. The second protective member (PCM2) may include at least one of polyimide (PI) and polyethylene terephthalate (PET).

[0052] In the electronic device (ED), a first non-folding region (NFA1), a folding region (FA), and a second non-folding region (NFA2) may be defined. The folding region (FA) may overlap with the folding axis (FX) of FIGS. 1a and FIGS. 1b. The folding region (FA) of the electronic device (ED) may comprise a material having flexibility. Accordingly, when the electronic device (ED) is folded with respect to the folding axis (FX), the folding region (FA) may also bend. The folding region (FA) may be positioned between the first non-folding region (NFA1) and the second non-folding region (NFA2).

[0053] The support plate (PT) can be positioned below the display module (DM) to support the display module (DM). The support plate (PT) can be positioned between the display module (DM) and the cover member (CM).

[0054] The support plate (PT) may include an insulating material or a non-metallic material. For example, the support plate (PT) may include carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP).

[0055] A plurality of folding openings (OP-F) may be defined in the support plate (PT). The plurality of folding openings (OP-F) may overlap with the adhesive opening (OP-A). The plurality of folding openings (OP-F) may be arranged to have a lattice shape in a plane. The flexibility of the folding area (FA) may be improved by the plurality of folding openings (OP-F). Additionally, the plurality of folding openings (OP-F) may overlap the folding area (FA) in a first direction (DR1).

[0056] The cover member (CM) can be positioned on the lower part of the support plate (PT). The cover member (CM) can prevent foreign matter from entering the display module (DM) through a plurality of folding openings (OP-F).

[0057] An electronic device (ED) according to one embodiment of the present invention may include a fourth adhesive layer (AL4-1, AL4-2).

[0058] A portion (AL4-1) of the fourth adhesive layer (AL4) is placed between the support plate (PT) and the first digitizer (DGT1) to bond the support plate (PT) and the first digitizer (DGT1) together. Another portion (AL4-2) of the fourth adhesive layer (AL4) is placed between the support plate (PT) and the second digitizer (DGT2) to bond the support plate (PT) and the second digitizer (DGT2) together.

[0059] Digitizers (DGT1, DGT2) may be disposed on the lower part of the support plate (PT). The digitizers (DGT1, DGT2) may include a first digitizer (DGT1) and a second digitizer (DGT2). The first digitizer (DGT1) may be disposed at a position overlapping with the first non-folding area (NFA1). The second digitizer (DGT2) may be disposed at a position overlapping with the second non-folding area (NFA2). A portion of each of the first digitizer (DGT1) and the second digitizer (DGT2) may be disposed on the lower side of the cover member (CM). The first digitizer (DGT1) and the second digitizer (DGT2) may be disposed spaced apart with a predetermined gap. The predetermined gap may preferably be about 0.3 mm to 3 mm. However, it is not limited to this.

[0060] Digitizers (DGT1, DGT2) can detect input from an electromagnetic pen (not shown). Digitizers (DGT1, DGT2) can be driven by a method utilizing electromagnetic induction resonance (EMR).

[0061] Digitizers (DGT1, DGT2) include a plurality of loop coils (not shown). The plurality of loop coils can generate a magnetic field of a preset resonance frequency with the electronic pen. The magnetic field formed by the plurality of loop coils is applied to an LC resonance circuit composed of an inductor and a capacitor of the electronic pen. The coil generates current by the received magnetic field and transfers the generated current to the capacitor. Accordingly, the capacitor charges the current input from the coil and discharges the charged current to the coil. Consequently, a magnetic field of the resonance frequency is emitted from the coil. The magnetic field emitted by the electronic pen can be reabsorbed by the plurality of loop coils, thereby allowing the location of the electronic pen on the display panel (DP) to be determined.

[0062] Although not separately illustrated in this specification, an electromagnetic shielding layer (not shown) may be disposed below the digitizers (DGT1, DGT2). The electromagnetic shielding layer (not shown) may perform an electromagnetic shielding function. For example, the electromagnetic shielding layer may block electromagnetic waves generated from components disposed below the digitizers (DGT1, DGT2). Accordingly, the sensing sensitivity of the digitizers (DGT1, DGT2) may be improved.

[0063] The electromagnetic shielding layer (not shown) may include magnetic metal powder (MMP), ferrite, or invar. Additionally, the electromagnetic shielding layer (not shown) may include iron (Fe), silicon (Si), and / or aluminum (Al).

[0064] Metal layers (ML1, ML2) may be disposed below the digitizers (DGT1, DGT2). The metal layers (ML1, ML2) may include a first metal layer (ML1) and a second metal layer (ML2). The first metal layer (ML1) may overlap the first non-folding region (NFA1). The second metal layer (ML2) may overlap the second non-folding region (NFA2).

[0065] The metal layers (ML1, ML2) may include stainless steel (SUS), copper (Cu), or aluminum (Al). However, they are not limited thereto.

[0066] Although not separately illustrated in this specification, a heat dissipation layer (not illustrated) may be disposed below the metal layers (ML1, ML2). The heat dissipation layer can dissipate heat generated during the operation of the digitizers (DGT1, DGT2) to the outside.

[0067] FIG. 4 illustrates an exemplary cross-section of a display module (DM) according to one embodiment of the present invention.

[0068] The display module (DM) may include an impact absorption layer (ISL), a first sub-adhesive layer (SAL1), a display panel (DP), a second sub-adhesive layer (SAL2), a panel protection layer (PPL), a third sub-adhesive layer (SAL3), and a barrier layer (BRL).

[0069] An impact absorption layer (ISL) may be placed on the upper surface of a display panel (DP). The impact absorption layer (ISL) can protect the display panel (DP) by absorbing impact transmitted from the upper surface of the display panel (DP). The impact absorption layer (ISL) may include a flexible plastic material. For example, the impact absorption layer (ISL) may include a synthetic resin film. The synthetic resin film may include at least one of polyimide (PI), polycarbonate, polyamide, triacetylcellulose, and polyethylene terephthalate (PET).

[0070] The first sub-adhesive layer (SAL1) is placed between the shock-absorbing layer (ISL) and the display panel (DP) to bond the shock-absorbing layer (ISL) and the display panel (DP) together.

[0071] A display panel (DP) can emit light. The display panel (DP) includes a plurality of pixels, and each of the plurality of pixels may include a light-emitting element and a pixel circuit that controls the current value flowing through the light-emitting element. For example, the display panel (DP) may be any one of an organic light-emitting display panel, a quantum dot light-emitting display panel, a micro LED display panel, a liquid crystal display panel, an electrophoretic display panel, and an electrowetting display panel. The light-emitting layer of the organic light-emitting display panel may include an organic light-emitting material. The inorganic light-emitting display panel may include a quantum dot light-emitting display panel and a micro light-emitting display panel based on an inorganic material.

[0072] The second sub-adhesive layer (SAL2) is placed between the display panel (DP) and the panel protection layer (PPL) to bond the display panel (DP) and the panel protection layer (PPL) together.

[0073] A panel protection layer (PPL) may be placed on the underside of a display panel (DP). The panel protection layer (PPL) can protect the display panel (DP) by absorbing shocks transmitted from the underside of the display panel (DP). The panel protection layer (PPL) may include a flexible plastic material. For example, the panel protection layer (PPL) may include polyethylene terephthalate (PET).

[0074] The third sub-adhesive layer (SAL3) is placed between the panel protection layer (PPL) and the barrier layer (BRL) to bond the panel protection layer (PPL) and the barrier layer (BRL) together.

[0075] A barrier layer (BRL) may be placed below a panel protection layer (PPL). The barrier layer (BRL) can prevent deformation of the display panel (DP) due to pressure. For example, the barrier layer (BRL) may include at least one of polyimide (PI) or polyethylene terephthalate (PET).

[0076] FIG. 5 illustrates an exemplary cross-section of a display panel (DP) according to one embodiment of the present invention.

[0077] Referring to FIG. 5, the display panel (DP) may include a base layer (SB), a circuit layer (CL), a light-emitting element layer (LD), an encapsulation layer (TFE), and a touch sensing circuit (TSC).

[0078] The base layer (SB) can provide a base on which the circuit layer (CL) is placed. The base layer (SB) may have a flexible property that allows for bending, folding, or rolling. In one embodiment of the present invention, the base layer (SB) may be a glass substrate, a metal substrate, or a polymer substrate.

[0079] The base layer (SB) may be composed of polyethersulfone (PES), polyacrylate (PA), polyarylate (PAR), polyetherimide (PEI), polyethylene napthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polycarbonate (PC), cellulose triacetate (CAT), cellulose acetate propionate (CAP), or a combination thereof. However, it is not limited thereto.

[0080] The circuit layer (CL) may be disposed on the base layer (SB). The circuit layer (CL) may include a conductive pattern (not shown), a semiconductor pattern (not shown), a plurality of insulating layers (not shown), and a signal line (not shown), etc.

[0081] A light-emitting element layer (LD) may be disposed on a circuit layer (CL). The light-emitting element layer (LD) may include electrodes (not shown), functional layers (not shown), and a light-emitting element (not shown). The light-emitting element may include an organic light-emitting material, an inorganic light-emitting material, an organic-inorganic light-emitting material, a quantum dot, a quantum rod, a micro LED, or a nano LED.

[0082] The encapsulation layer (TFE) may be disposed on the light-emitting element layer (LD). The encapsulation layer (TFE) can protect the light-emitting element layer (LD) from foreign substances such as moisture, oxygen, and dust particles. The encapsulation layer (TFE) may include an inorganic layer and an organic layer. For example, the encapsulation layer (TFE) may have a structure in which a first inorganic layer (not shown), an organic layer (not shown), and a second inorganic layer (not shown) are sequentially stacked.

[0083] A touch sensing circuit (TSC) may be placed on a display panel (DP). The touch sensing circuit (TSC) may be driven by a capacitive or resistive method. The touch sensing circuit (TSC) may detect the position or intensity of a user's hand applied. The touch sensing circuit (TSC) may include sensing electrodes insulated from each other, routing wires connected to corresponding sensing electrodes, and at least one sensing insulating layer.

[0084] An anti-reflective layer (not shown) may be disposed on a touch sensing circuit (TSC). The anti-reflective layer (not shown) may reduce the reflectivity of external light incident from the outside. The anti-reflective layer (not shown) may include color filters.

[0085] Figure 6 is an enlarged view of section AA of Figure 3.

[0086] Referring to FIG. 6, the upper surface of the display module (DM) is rough and can have high surface roughness.

[0087] Accordingly, the lower surface of the first adhesive layer (AL1) disposed on the upper surface of the display module (DM) may also be uneven and have a high surface roughness corresponding to the upper surface of the display module (DM). However, the upper surface of the first adhesive layer (AL1) is flat, and accordingly, the surface roughness of the upper surface of the first adhesive layer (AL1) may be smaller than the surface roughness of the lower surface of the first adhesive layer (AL1).

[0088] In one embodiment of the present invention, the first adhesive layer (AL1) may include a first initiator and a second initiator different from the first initiator.

[0089] In one embodiment of the present invention, the first initiator may be a substance that initiates a polymerization reaction when heat having a predetermined temperature is applied. For example, the first initiator may include azobisisobutyronitrile, but is not limited thereto.

[0090] In one embodiment of the present invention, the second initiator may be a substance that initiates a polymerization reaction when light having a predetermined wavelength is applied. For example, the second initiator may include at least one of a ketone-based substance (benzophenone, 2-chlorothixoanthone) and a benzyl ketone-based substance (e.g., 2,2-dimethoxy-2phenyl-acetophenone or hydroxy-cyclohexyl-phenyl).

[0091] In one embodiment of the present invention, the second adhesive layer (AL2, see FIG. 3) may include a third initiator. The third initiator may be different from the first initiator and the second initiator. The second adhesive layer (AL2, see FIG. 3) may further include a first initiator.

[0092] In one embodiment of the present invention, the third initiator may be a substance that initiates a polymerization reaction when a predetermined amount of heat is applied. The temperature at which the third initiator initiates the polymerization reaction may be different from the temperature at which the first initiator initiates the polymerization reaction.

[0093] Accordingly, the first adhesive layer (AL1) may include a thermal curing initiator that initiates a polymerization reaction when heat is applied and a photopolymerization initiator that initiates a polymerization reaction when light is applied. On the other hand, the second adhesive layer (AL2) may include only two types of thermal curing initiators that initiate a polymerization reaction when heat having different temperatures is applied, and may not include a photopolymerization initiator. Since the first protective member (PCM1) disposed on the upper part of the first adhesive layer (AL1) contains a transparent material and can transmit light, the first adhesive layer (AL1) can receive light during the manufacturing process. Accordingly, the photopolymerization initiator of the first adhesive layer (AL1) can initiate a polymerization reaction. On the other hand, the display module (DM) and the support plate (PT) disposed on both sides of the second adhesive layer (AL2) cannot transmit light. Accordingly, since the second adhesive layer (AL2) cannot induce a polymerization reaction using light, it contains only thermosetting initiators.

[0094] As such, since the types of initiators in the first adhesive layer (AL1) and the types of initiators in the second adhesive layer (AL2) are different, the surface roughness of each of the first adhesive layer (AL1) and the second adhesive layer (AL2) also differs.

[0095] Specifically, the first adhesive layer (AL1) includes a flat upper surface and a rough lower surface, but the second adhesive layer may include a rough upper surface and a rough lower surface. Accordingly, the surface roughness of the upper surface of the second adhesive layer (AL2) may be greater than the surface roughness of the upper surface of the first adhesive layer (AL1).

[0096] In the preceding example, the first initiator was exemplified as a thermal curing initiator and the second initiator as a photopolymerization initiator, but is not limited thereto. In other embodiments of the present invention, the first initiator may be a thermal curing initiator or a photopolymerization initiator, and the second initiator may be a photopolymerization initiator or a moisture curing initiator.

[0097] FIG. 7 is a flowchart of a method for manufacturing a display device (S10) according to an embodiment of the present invention. FIGS. 8a to 8e are drawings corresponding to each step of the method for manufacturing a display device (S10).

[0098] The method for manufacturing a display device (S10) may include a preparation step (S100), an adhesive layer placement step (S200), a protective member placement step (S300), a flattening step (S400), and a photocuring step (S500).

[0099] Referring to FIGS. 7 and FIGS. 8a, a display module (DM) can be prepared in the preparation step (S100). Since the display module (DM) has a structure in which a number of thin layers are stacked in order to be folded, the upper surface of the display module (DM) has a rough shape due to the influence of these thin layers.

[0100] Referring to FIGS. 7 and FIGS. 8b, a first adhesive layer (AL1) can be placed on a display module (DM) in the adhesive layer placement step (S200).

[0101] Immediately after the first adhesive layer (AL1) is placed on the display module (DM), the upper and lower surfaces of the first adhesive layer (AL1) may also have a rough shape following the rough shape of the display module (DM). Additionally, before the process of placing the first adhesive layer (AL1) on the display module (DM) is performed, both sides of the first adhesive layer (AL1) may be protected by release films. The release films contain silica particles, and the upper and lower surfaces of the first adhesive layer (AL1) may also have a rough shape due to the silica particles. That is, due to the shape of the display module (DM) and the silica particles, the surface roughness of each of the upper and lower surfaces of the first adhesive layer (AL1) may be high.

[0102] In the adhesive layer placement step (S200), the creep value of the first adhesive layer (AL1) may be 150% or more and 300% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C. If the creep value of the first adhesive layer (AL1) is less than 150% when a stress of 2000 Pa is applied for 10 minutes at 25°C, a problem arises in which the first adhesive layer (AL1) is not sufficiently flattened because the degree of deformation of the first adhesive layer (AL1) in the flattening step (S400) described below is too small. If the creep value of the first adhesive layer (AL1) exceeds 300% when a stress of 2000 Pa is applied for 10 minutes at 25°C, the degree of deformation of the first adhesive layer (AL1) becomes too large when the first protective member (PCM1) is placed in the protective member placement step (S300) described below. Consequently, a problem arises in which the upper and lower surfaces of the first adhesive layer (AL1) become uneven and more uneven. In addition, a problem also arises in which process convenience is reduced when placing the first adhesive layer (AL1) because the creep value of the first adhesive layer (AL1) is too large.

[0103] Referring to FIGS. 7 and FIGS. 8c, in the protective member placement step (S300), a first protective member (PCM1) containing a transparent material can be placed on the first adhesive layer (AL1). The first protective member (PCM1) has a thin thickness and has flexible properties. Accordingly, the upper and lower surfaces of the first protective member (PCM1) can also have a rough shape along with the rough shape of the first adhesive layer (AL1).

[0104] Referring to FIG. 7 and FIG. 8d, a predetermined time may be waited during the flattening step (S400). The predetermined time may be approximately 50 minutes or more and 24 hours or less. As previously described in the adhesive layer placement step (S200), due to the creep characteristics of the first adhesive layer (AL1), the upper surface of the first adhesive layer (AL1) may become flat over time. As the upper surface of the first adhesive layer (AL1) becomes flat, the upper and lower surfaces of the first protective member (PCM1) may also become flat.

[0105] Referring to FIGS. 7 and 8e, in the photocuring step (S500), light having a predetermined wavelength (e.g., UV light) is irradiated onto the upper surface of the first protective member (PCM1) so that the first adhesive layer (AL1) can be cured. The creep value of the first adhesive layer (AL1) cured in the photocuring step (S500) may be 80% or more and 130% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C. Since the creep value of the first adhesive layer (AL1) is lowered by the photocuring step (S500), the upper surface of the first adhesive layer (AL1) can be maintained in a flat state. Since the upper surface of the first adhesive layer (AL1) is flat, other components disposed on the first adhesive layer (AL1) can also have a low surface roughness. Accordingly, since the display area (DA) of the electronic device (ED) according to one embodiment of the present invention has low surface roughness, a display area (DA) having high quality can be provided.

[0106] Although the first adhesive layer (AL1) was described in FIGS. 8a to 8e, in other embodiments of the present invention, the process described in FIGS. 8a to 8e can be applied in the same way to the second to fourth adhesive layers (AL2 to AL4) and sub-adhesive layers (SAL1, SAL2, SAL3).

[0107] FIG. 9 illustrates the change in roughness of the display area (DA) of the electronic device (ED) according to the waiting time in the flattening step (S400). In FIG. 9, the Kc value representing the degree of roughness is a value measured by Phase Measuring Deflectometry (PMD), and is a curvature value measured for a waveness having a wavelength range of 1.0 mm or more and 3.0 mm or less.

[0108] division Comparative example The present invention Creep value of the adhesive layer 54.5% 156% Flattening time Time 0hr 24hr 0hr 24hr asperity Kc 0.32 0.26 0.26 0.12

[0109] [Table 1] compares the data of the comparative example with the data of the present invention in relation to the graph of FIG. 9. Referring to FIG. 9 and [Table 1], the creep value of the adhesive layer of the comparative example during the adhesive layer placement step (S200) is 54.5% when a stress of 2000 Pa is applied for 10 minutes at 25°C. The creep value of the first adhesive layer (AL1) of the present invention during the adhesive layer placement step (S200) is 156% when a stress of 2000 Pa is applied for 10 minutes at 25°C. The comparative example concerns the change in roughness when using an adhesive layer having a lower creep value than the first adhesive layer (AL1) of the present invention. Since the adhesive layer of the comparative example has a low creep value, the Kc value decreases by only about 12% after about 500 minutes have elapsed.

[0110] On the other hand, since the first adhesive layer (AL1) of the present invention has a higher creep value than the adhesive layer of the comparative example, it can be confirmed that the Kc value is reduced by about 30% after about 500 minutes.

[0111] According to the present invention, it can be confirmed that the Kc value decreases to approximately 0.22 after 50 minutes have elapsed in the flattening step (S400), and the Kc value decreases to approximately 0.20 after 500 minutes have elapsed. Additionally, it can be confirmed that the Kc value decreases to approximately 0.12 after 24 hours have elapsed.

[0112] If the waiting time in the flattening step (S400) is less than 50 minutes, the Kc value is not lowered sufficiently yet, so it is not sufficient to improve the display quality. Also, if the waiting time in the flattening step (S400) exceeds 24 hours, the waiting time becomes too long, which may lower the efficiency of the manufacturing process. Therefore, through FIG. 9, it can be confirmed that the waiting time for flattening in the flattening step (S400) is preferably between 50 minutes and 24 hours.

[0113] In this way, as the Kc value of the first adhesive layer (AL1) decreases, the Kc value of other components disposed on the first adhesive layer (AL1) may also decrease. Specifically, the Kc value of at least one of the first adhesive layer (AL1), the first protective member (PCM1), the third adhesive layer (AL3), and the second protective member (PCM2) may be 0.1 or more and 0.2 or less.

[0114] FIG. 10 illustrates a portion of the display area (DA) of an electronic device (ED) according to one embodiment of the present invention and a portion of the display area of ​​a comparative example. Referring to FIG. 10, it can be seen that the present invention has lower roughness than the comparative example and thus has better display quality.

[0115] FIG. 11 illustrates an exemplary block diagram of an electronic device (ED) according to one embodiment.

[0116] Referring to FIG. 11, an electronic device (ED) according to one embodiment may include a display module (DM), a processor (PCS), a memory (MMR), and a power module (PM).

[0117] The processor (PCS) may include at least one of a central processing unit (CPU), an application processor (AP), a graphic processing unit (GPU), a communication processor (CP), an image signal processor (ISP), and a controller.

[0118] The memory (MMR) may store data information necessary for the operation of the processor (PCS) or the display module (DM). When the processor (PCS) executes an application stored in the memory (MMR), video data signals and / or input control signals are transmitted to the display module (DM), and the display module (DM) can process the received signals to output video information through a display screen.

[0119] The power module (PM) may include a power supply module, such as a power adapter or battery device, and a power conversion module that converts the power supplied by the power supply module to generate power required for the operation of an electronic device (ED).

[0120] At least one of each component of the electronic device (ED) described above may be included within the display device according to the embodiments described above. Additionally, some of the individual modules functionally included within a single module may be included within the display device, while others may be provided separately from the display device. For example, the display device may include a display module (DM), and the processor (PCS), memory (MMR), and power module (PM) may be provided in the form of other devices within the electronic device (ED) that are not the display device.

[0121] FIG. 12 illustrates schematic diagrams of electronic devices (ED) according to various embodiments.

[0122] Referring to FIG. 12, various electronic devices to which a display device according to the embodiments is applied may include not only image display electronic devices such as a smartphone (ED-1a), a tablet PC (ED-1b), a laptop (ED-1c), a TV (ED-1d), or a desk monitor (ED-1e), but also wearable electronic devices including a display module such as smart glasses (ED-2a), a head-mounted display (ED-2b), or a smart watch (ED-2c), and automotive electronic devices (ED-3) including a display module such as a CID (Center Information Display) or a room mirror display placed on the instrument panel, center fascia, or dashboard of a car.

[0123] Although the invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims. Furthermore, the exemplary embodiments disclosed in the invention are not intended to limit the technical spirit of the invention, and all technical spirits within the scope of the following claims and their equivalents should be interpreted as being included within the scope of the rights of the invention. Explanation of the symbols

[0124] ED: Electronic device DM: Display Module DP: Display panel WM: Window Module PT: Support Plate CM: Cover member AL1~AL4: Adhesive layer PCM1: First protective member PCM2: Second protective member DGT: Digitizer ML: Metal layer TSC: Touch detection circuit

Claims

Claim 1 A display device comprising: a display module; a first adhesive layer disposed on the display module and comprising a first initiator and a second initiator different from the first initiator; a first protective member disposed on the first adhesive layer; a second adhesive layer disposed below the display module and comprising a third initiator, wherein the third initiator is different from the first initiator and the second initiator; and a support plate disposed below the second adhesive layer. Claim 2 A display device according to claim 1, wherein the first initiator is a substance that initiates a polymerization reaction when heat having a predetermined temperature is applied, and the second initiator is a substance that initiates a polymerization reaction when light having a predetermined wavelength is applied. Claim 3 In claim 2, the third initiator is a substance that initiates a polymerization reaction when heat having a temperature different from the predetermined temperature is applied. Claim 4 A display device according to claim 3, wherein the first initiator comprises azobisisobutyronitrile, and the second initiator comprises at least one of a ketone-based substance and a benzyl ketone-based substance. Claim 5 A display device according to claim 1, wherein the surface roughness of the lower surface of the first adhesive layer is greater than the surface roughness of the upper surface of the first adhesive layer. Claim 6 In claim 5, a display device in which the surface roughness of the upper surface of the second adhesive layer is greater than the surface roughness of the upper surface of the first adhesive layer. Claim 7 A display device according to claim 1, further comprising: a third adhesive layer disposed on the first protective member; and a second protective member disposed on the third adhesive layer, wherein each of the display module, the first adhesive layer, the first protective member, the second adhesive layer, the support plate, the third adhesive layer, and the second protective member is foldable. Claim 8 A display device according to claim 7, wherein a plurality of folding openings are defined in the support plate and an adhesive opening that overlaps with the plurality of folding openings is defined in the second adhesive layer. Claim 9 A display device according to claim 7, wherein at least one of the second protective member, the third adhesive layer, the first protective member, and the first adhesive layer has a Kc value of 0.1 or more and 0.2 or less, and the Kc value is a value measured by Phase Measuring Deflectometry (PMD) and is a curvature value measured for a waveness having a wavelength range of 1.0 mm or more and 3.0 mm or less. Claim 10 An electronic device comprising: a display module; a first adhesive layer disposed on the display module, wherein the surface roughness of the lower surface is greater than the surface roughness of the upper surface facing the lower surface; a first protective member disposed on the first adhesive layer; a second adhesive layer disposed below the display module; and a support plate disposed below the second adhesive layer. Claim 11 In claim 10, the first adhesive layer comprises a first initiator and a second initiator different from the first initiator, in an electronic device. Claim 12 An electronic device according to claim 11, wherein the first initiator is a substance that initiates a polymerization reaction when heat having a predetermined temperature is applied, and the second initiator is a substance that initiates a polymerization reaction when light having a predetermined wavelength is applied. Claim 13 An electronic device according to claim 12, wherein the first initiator comprises azobisisobutyronitrile, and the second initiator comprises at least one of a ketone-based substance and a benzyl ketone-based substance. Claim 14 An electronic device according to claim 13, further comprising: a third adhesive layer disposed on the first protective member; and a second protective member disposed on the third adhesive layer, wherein each of the display module, the first adhesive layer, the first protective member, the second adhesive layer, the support plate, the third adhesive layer, and the second protective member is foldable. Claim 15 An electronic device according to claim 14, wherein at least one of the second protective member, the third adhesive layer, the first protective member, and the first adhesive layer has a Kc value of 0.1 or more and 0.2 or less, and the Kc value is a value measured by Phase Measuring Deflectometry (PMD) and is a curvature value measured for a waveness having a wavelength range of 1.0 mm or more and 3.0 mm or less. Claim 16 A method for manufacturing a display device comprising: a preparation step in which a display module is prepared; an adhesive layer placement step in which an adhesive layer is placed on the display module, wherein the creep value of the adhesive layer is 150% or more and 300% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C; a protective member placement step in which a protective member including a transparent material is placed on the adhesive layer; and a flattening step of waiting for a predetermined time after the protective member placement step. Claim 17 A method for manufacturing a display device according to claim 16, further comprising a photocuring step in which light having a predetermined wavelength is irradiated onto the upper part of the protective member, and the adhesive layer is cured by the light. Claim 18 A method for manufacturing a display device according to claim 17, wherein the creep value of the adhesive layer after the photocuring step is 80% or more and 130% or less when a stress of 2000 Pa is applied for 10 minutes at 25°C. Claim 19 A method for manufacturing a display device according to claim 18, wherein the surface roughness of the lower surface of the adhesive layer is greater than the surface roughness of the upper surface of the adhesive layer. Claim 20 A method for manufacturing a display device according to claim 16, wherein the predetermined time is 50 minutes or more and 24 hours or less.

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