Method of manufacturing cover window and method of manufacturing flexible display device

Abstract

Disclosed are a method of manufacturing a cover window for a display device and a method of manufacturing a flexible display device, the method of manufacturing a cover window for a display device including: providing a glass substrate having a bendable region and a flat region; modifying the bendable region by irradiating the glass substrate with a beam; and etching the bendable region to have a thickness thinner than the flat region. Due to the modification of the bendable region, the bendable region can have a faster etching rate than the flat region.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2020-0101609, filed with the Korean Intellectual Property Office on August 13, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a flexible display device, a cover window for a flexible display device, and a method for manufacturing a cover window for a flexible display device. Background Technology

[0004] Electronic devices such as mobile phones, tablet computers, multimedia players, and televisions include display devices for displaying images. A display device includes a display panel that displays the image on a screen. Flexible display devices using flexible display panels as the display panel have been developed.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the background art, and therefore may contain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0006] Flexible display devices may include a cover window that transmits an image displayed on the flexible display panel while protecting the flexible display panel from external environmental factors (e.g., impact). Glass may be used for the cover window. When the cover window is thin, its flexibility (flexibility) can be increased, but its impact resistance can be degraded. Therefore, it may be desirable to partially thin a predetermined portion of the cover window that exhibits flexible properties.

[0007] The embodiments include a method of manufacturing a cover window, the method comprising forming a predetermined area of ​​the cover window as thin and improving desired characteristics of the cover window. The embodiments also include a method for manufacturing a flexible display device including a cover window.

[0008] A method for manufacturing a cover window for a display device according to an embodiment includes: providing a glass substrate comprising a flexible region and a flat region; modifying the flexible region by irradiating the glass substrate with a beam; and etching the flexible region to make the flexible region have a thickness thinner than the flat region.

[0009] The beam can be a laser beam or a halogen beam.

[0010] A bundle can be a wire bundle or a planar bundle.

[0011] The bundle can have an intensity that decreases from the center of the bendable region toward the boundary between the bendable region and the flat region.

[0012] When modifying the bendable region, the modification depth of the glass substrate can be reduced from the center of the bendable region toward the boundary between the bendable region and the flat region.

[0013] Because of the task of modifying the flexible region, the flexible region can be etched faster in the etching task than the flat region.

[0014] Etching the flexible region may also include heating the flexible region to a higher temperature than the flat region.

[0015] When heated, the temperature applied to the bendable region can have a Gaussian distribution relative to the centerline of the bendable region.

[0016] When etching the flexible area, grooves can be formed in the flexible area.

[0017] The groove can have a depth that decreases from the center of the bendable region toward the boundary between the bendable region and the flat region.

[0018] A method for manufacturing a flexible display device according to an embodiment includes: providing a glass substrate including a bendable region and a flat region; irradiating at least the bendable region of the glass substrate with a beam; etching the glass substrate, wherein the bendable region is etched faster than the flat region; and attaching a display panel to the glass substrate.

[0019] The beam can be a laser beam or a halogen beam.

[0020] A bundle can be a wire bundle or a planar bundle.

[0021] The bundle can have an intensity that decreases from the center of the bendable region toward the boundary between the bendable region and the flat region.

[0022] When irradiated with a beam, the glass substrate can be modified to have a depth that decreases from the center of the bendable region toward the boundary between the bendable region and the flat region.

[0023] Because of the beam irradiation, the flexible areas can be etched faster than the flat areas during etching.

[0024] Etching a glass substrate may include heating the flexible region to a higher temperature than the flat region.

[0025] When heated, the temperature applied to the bendable region can have a Gaussian distribution relative to the centerline of the bendable region.

[0026] Grooves can be formed in flexible areas when etching glass substrates.

[0027] The flexible region may have a grooved surface forming a groove, and the grooved surface may have a series of radii of curvature. One end and the other end of the grooved surface may each have the smallest radius of curvature from the series of radii of curvature.

[0028] According to embodiments of this disclosure, a predetermined region (e.g., a flexible region) of the cover window can be formed thin, which can improve the impact resistance and flexibility of the cover window. Furthermore, the yield rate of the cover window manufacturing process can be improved, and this can facilitate stable external dimensions. Additionally, the cross-section of the thin region (e.g., the flexible region) can be etched with a Gaussian distribution, and a cover window in which the boundary between the thin and thick regions is not visually recognizable or perceived by the user can be provided. Moreover, beneficial effects are apparent throughout the specification according to embodiments. Attached Figure Description

[0029] Figure 1A , Figure 1B and Figure 1C This is a schematic perspective view of a flexible display device according to an embodiment.

[0030] Figure 2 This is a flowchart of a method for manufacturing a display device according to an embodiment.

[0031] Figure 3A , Figure 3B and Figure 3C This is a schematic diagram of a method for manufacturing a cover window according to an embodiment.

[0032] Figure 4A and Figure 4B This is a schematic diagram of wire harness forming during the manufacturing process.

[0033] Figure 5 This is a schematic diagram of planar bundle forming during the manufacturing process.

[0034] Figure 6 A diagram showing the distribution of light beams illuminating the bendable region of the cover window during the manufacturing process is shown.

[0035] Figure 7 This is a schematic diagram of the etching task in the manufacturing method of the cover window according to the embodiment.

[0036] Figure 8 This is a perspective view of the task of attaching a display panel in a method for manufacturing a display device according to an embodiment.

[0037] Figure 9 This is a perspective view of the task of attaching a display panel in a method for manufacturing a display device according to an embodiment.

[0038] Figure 10 yes Figure 9The cross-sectional view of the display device shown is taken along a first direction.

[0039] Figure 11 This is a schematic cross-sectional view of the layered structure of the display panel according to the embodiment. Detailed Implementation

[0040] The inventive concept will be described more fully below with reference to the accompanying drawings, in which embodiments of the inventive concept are illustrated.

[0041] In the accompanying drawings, the thickness of layers, films, panels, areas, etc., has been exaggerated for clarity.

[0042] It should be understood that when an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it can be directly on that other element, or there may be intervening elements. Conversely, when an element is referred to as being “directly” on another element, there are no intervening elements.

[0043] Furthermore, unless explicitly stated otherwise, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply inclusion of the stated element but not exclusion of any other element.

[0044] Throughout the specification, “connection” means not only when two or more components are directly connected, but also when two or more components are indirectly connected through another component, or when they are physically or electrically connected, and it can include cases where parts that are essentially a whole are connected to each other, although these parts are referred to by different names depending on their location or function.

[0045] In the accompanying drawings, the symbols “x”, “y”, and “z” are used to indicate directions, where “x” is a first direction, “y” is a second direction perpendicular to the first direction, and “z” is a third direction perpendicular to both the first and second directions. The first direction (x-axis direction), the second direction (y-axis direction), and the third direction (z-axis direction) can correspond to the horizontal direction, vertical direction, and thickness direction of the display device, respectively.

[0046] Unless otherwise stated in the specification, “overlap” means overlap in a plan view and overlap in a third direction (z-axis direction).

[0047] Figure 1A , Figure 1B and Figure 1C This is a schematic perspective view of a flexible display device according to an embodiment. Figure 1A , Figure 1B and Figure 1CThe flexible display device is shown in its unfolded state, first folded state, and second folded state.

[0048] The flexible display device 1 (hereinafter referred to as display device 1) can be as follows: Figure 1A The unfolding shown is completely flat, and can be as follows: Figure 1B and / or Figure 1C The foldable display device 1 is shown as foldable. The display device 1 may include a bendable region BA and a first flat region FA1 and a second flat region FA2 disposed on opposite sides of the bendable region BA. The bendable region BA is the portion that bends when the display device 1 is folded (or in a folded configuration), and the first flat region FA1 and the second flat region FA2 are the portions that do not bend.

[0049] Although a single bendable region BA is shown in the illustrated embodiment, in one or more embodiments, the display device 1 may include a plurality of bendable regions BA spaced apart from each other (e.g., the display device 1 may include a plurality of bendable regions BA capable of bending with different radii of curvature). For example, the display device 1 may include two or more bendable regions and three or more flat regions.

[0050] Display device 1 may include a display area DA for displaying images and a non-display area NA surrounding the display area DA. The display area DA may correspond to a screen with pixels PX arranged thereon. The non-display area NA may correspond to a bezel. Display device 1 may include a display panel that implements the screen and a cover window that covers the display panel.

[0051] like Figure 1B As shown, the display device 1 can be folded (hereinafter referred to as inward folding) so that the screen portions face each other, that is, the screen portions of the first flat region FA1 and the second flat region FA2 face each other. Figure 1C As shown, the display device 1 can be folded (hereinafter referred to as outward folding) such that the screen is exposed to the outside (i.e., the screen portions of the first flat region FA1 and the second flat region FA2 are facing away from each other). In the inward folded state, the screen portion of the flexible region BA can be hidden. In the outward folded state, the screen portion of the flexible region BA can be exposed for the user to see. The display device 1 can be designed to allow only one or both of inward and outward folding. When the display device 1 includes multiple flexible regions BA, one of the multiple flexible regions BA can be a flexible region capable of inward folding, and another of the multiple flexible regions BA can be a flexible region capable of outward folding.

[0052] The display device 1 may also include a housing and various components constituting the display device 1, such as a display panel, a driving device, a flexible printed circuit (FPC), an application processor, a memory, a speaker, and various sensors that can be positioned within the space limited by the cover window and the housing.

[0053] Figure 2 This is a flowchart of a method for manufacturing a display device according to an embodiment, and Figure 3A , Figure 3B and Figure 3C This is a schematic diagram of a method for manufacturing a cover window according to an embodiment.

[0054] Reference Figure 2 The method of manufacturing a display device may include: providing a glass substrate (S10); pre-treating the glass substrate (S20); etching a flexible region of the glass substrate (S30); chemically strengthening the glass substrate (S40); and attaching a display panel to the glass substrate (S50).

[0055] Reference Figure 2 and Figure 3A The task of providing the glass substrate GS (S10) may include preparing an optically transparent glass substrate GS having an overall constant thickness or a substantially constant overall thickness (e.g., a thickness of about 50 μm to about 200 μm). The glass substrate GS may be a cellular cell (corresponding to one cover window) or a motherboard cell (corresponding to multiple cover windows). For ease of handling, the glass substrate GS may be fixed to a stage. A flexible region BA and flat regions FA1 and FA2 on the corresponding sides of the flexible region BA may be defined in the glass substrate GS.

[0056] Reference Figure 2 and Figure 3B A pretreatment (S20) task of the flexible region BA of the glass substrate GS can be performed after the task of providing the glass substrate GS (S10). The pretreatment (S20) modifies the glass material of the flexible region BA by irradiating it with one or more beams. Compared to unmodified flat regions FA1 and FA2 that are not irradiated or are not irradiated to the same extent or degree as the flexible region BA, the modified flexible region BA can be etched more effectively (e.g., exhibiting an increased etching rate). Therefore, the pretreatment (S20) task is configured to increase the etching selectivity of the flexible region BA in the subsequent etching (S30) task.

[0057] The irradiation beam used in the pretreatment (S20) task can be a laser beam or a halogen beam. The beam energy can exceed the limit required to modify the glass substrate GS. Modifying the glass substrate GS can achieve changes in the refractive index, material density, melting capacity, compaction capacity, ablation capacity, and / or chemical changes of the flexible region BA of the glass substrate GS. Furthermore, modification can include causing the material to crack to create microcracks or voids that can promote the penetration of etchants. Additionally, modification can alter the bond angles of the silicon oxide (e.g., silicon dioxide) constituting (or included within) the glass substrate GS. The level of modification of the glass substrate GS (i.e., the extent or degree of modification) can decrease from the center of the flexible region BA towards the boundary between the flexible region BA and the flat regions FA1 and FA2. The depth of modification of the properties of the bendable region BA (e.g., refractive index, material density, melting capacity, ablation capacity, and / or chemical changes) achieved in the pretreatment (S20) task can decrease from the center of the bendable region BA toward the boundary between the bendable region BA and the flat regions FA1 and FA2 (i.e., the depth of modification of the bendable region BA can be at its maximum at the center of the bendable region BA, and the depth of modification of the bendable region BA can decrease in the +x-axis direction and the -x-axis direction toward the boundary between the bendable region BA and the flat regions FA1 and FA2).

[0058] Reference Figure 2 and Figure 3C After pre-treating the glass substrate GS (S20), etching the flexible region BA of the glass substrate GS can be performed (S30). By etching the flexible region BA, a groove GV can be formed in the flexible region BA, and the thickness of the flexible region BA can become thinner than the thickness of the flat regions FA1 and FA2. For example, after the task of etching the flexible region BA (S30), the thickness of the thinnest part of the flexible region BA can be about 50 μm or less, about 40 μm or less, or about 30 μm or less. The thickness of the flat regions FA1 and FA2 can be about 50 μm or more, about 60 μm or more, or about 70 μm or more. The groove GV can be formed along a second direction with a predetermined depth and width. Figure 3CThe groove GV is formed along the second direction (y-axis direction) (i.e., the groove GV can be longitudinally oriented along the second direction (y-axis direction) with a predetermined depth and width). The width of the groove GV can be the same as or nearly the same as the width of the flexible region BA. As the depth of the groove GV increases, the thickness of the flexible region BA can decrease. The depth of the groove GV can decrease in the direction starting from the center of the flexible region BA and toward the boundary between the flexible region BA and the flat regions FA1 and FA2 (i.e., the depth of the groove GV can be at its maximum at the center of the flexible region BA, and the depth of the groove GV can decrease in the +x-axis direction and the -x-axis direction toward the boundary between the flexible region BA and the flat regions FA1 and FA2).

[0059] In the etching (S30) task, wet etching methods such as spraying, immersion, and / or downflow can be used. In the etching (S30) task, the entire glass substrate GS can be exposed to the etchant. Therefore, not only the flexible region BA, but also the flat regions FA1 and FA2 can be etched. However, since the flexible region BA is modified through the pretreatment (S20) task, the etching rate of the flexible region BA can be increased compared to the etching rate of the flat regions FA1 and FA2 that are not modified through the pretreatment (S20) task. Furthermore, the etching reaction rate of the flexible region BA can be increased by increasing the temperature of the flexible region BA during the etching (S30) task, thereby increasing the etching selectivity of the flexible region BA, which will be described later. In one or more embodiments, during the etching (S30) task, only the flexible region BA may be exposed to the etchant.

[0060] A cover window suitable for a flexible display device can be manufactured by selectively reducing the thickness of the flexible region BA and relatively increasing the thickness of the flat regions FA1 and FA2 (e.g., reference). Figures 8 to 10 (Cover window CW). That is, it can increase the impact resistance of the flat areas FA1 and FA2 in the cover window CW, and can improve the flexibility of the flexible area BA.

[0061] The increased thickness of the flat areas FA1 and FA2 is not only effective in protecting the display panel, but also in preventing damage to the cover window CW.

[0062] During the process steps, the cover window CW (or glass substrate GS) can be loaded into the cassette and transported. The portion of the glass substrate GS that contacts the cassette due to selective etching (i.e., flat regions FA1 and FA2) can be formed at a predetermined thickness, thereby reducing the breakage rate of the portion of the glass substrate GS in contact with the cassette and improving the yield.

[0063] A cover window CW corresponding to a predetermined size can be fabricated by an etching (S30) task, and a task to increase the strength of the cover window CW (e.g., chemically strengthening the glass substrate GS (S40)) can be performed after the etching (S30) task. Chemical strengthening (S40) may include replacing the ions in the glass substrate GS with other ions. For example, when the glass substrate GS is immersed in a high-temperature molten alkali metal salt, sodium ions (Na+) on the surface of the glass substrate GS... + Some of them are exchanged for potassium ions (K). + Potassium ions (K) + ) compared to sodium ions (Na + The strength of the glass substrate GS is increased, and when cooled, a compressive stress layer is formed in the glass substrate GS.

[0064] The shaping of the beam irradiated onto the glass substrate GS in the pretreatment (S20) task will now be described.

[0065] Figure 4A and Figure 4B This is a schematic diagram of wire harness forming. Figure 5 This is a schematic diagram of planar beam forming, and Figure 6 A diagram showing the light distribution of a beam illuminating a flexible region of a cover window (or glass substrate) is shown.

[0066] In the pretreatment (S20) task used for modifying glass materials, the glass substrate GS can be irradiated with a beam LB. For example... Figure 4A As shown, a line-beam LB can be achieved by passing a laser beam emitted from a laser source (e.g., a picosecond or femtosecond laser source) through a cylindrical lens. Line-beam LB is easy to implement, but achieving the appropriate level or degree of uniformity can be difficult. Figure 4B As shown, when multiple lenses and multiple reflectors are combined, a highly uniform line beam (LB) can be achieved while controlling the path of the laser beam emitted from the laser source. Figure 4A In the middle, the image on the right is an irradiance map of the line bundle LB formed using a cylindrical lens, and in... Figure 4B In the middle, the image on the right is an irradiance diagram of the line bundle LB formed by combining multiple lenses and multiple reflectors. It can be seen that... Figure 4B The LB ratio of the harness (which uses multiple lenses and mirrors) is higher. Figure 4A The LB (which uses a single lens) has a more uniform wire harness.

[0067] In the preprocessing (S20) task, the following can be used: Figure 4BThe wire harness LB shown illuminates the flexible region BA of the glass substrate GS. For example, when the width of the wire harness LB is set to correspond to the width of the flexible region BA, the entire flexible region BA can be illuminated at once without scanning the wire harness LB. The wire harness LB can be a Gaussian beam, a Bessel-Gaussian beam, or a Bessel beam.

[0068] Reference Figure 5 A planar beam PB (also referred to hereinafter as a planar beam PB) can be formed using a halogen lamp (or halogen flash lamp). For example, a planar beam PB illuminating a glass substrate GS can be formed by combining a filter (e.g., a homogenizer DOE) with a halogen flash lamp that emits a halogen beam. For example, the diffusion angle θ of the halogen beam through the focusing lens can be controlled. f A planar beam PB of predetermined size is formed. Furthermore, the intensity can be adjusted so that energy can be concentrated in the flexible region BA of the glass substrate GS, and the flexible region BA can be modified. In the pretreatment (S20) task, the planar beam PB can be irradiated onto the flat regions FA1 and FA2 of the glass substrate GS, but the energy intensity irradiating the flat regions FA1 and FA2 is weaker than the energy intensity irradiating the flexible region BA, and therefore the flat regions FA1 and FA2 may not be modified or may be modified to a very shallow depth (i.e., the degree to which the flat regions FA1 and FA2 are modified by the planar beam PB can be less than the degree to which the flexible region BA is modified by the planar beam PB). Therefore, in the subsequent etching (S30) process, the etch selectivity between the flexible region BA and the flat regions FA1 and FA2 can be increased (i.e., the flexible region BA can be more sensitive to etching than the flat regions FA1 and FA2). Besides halogen lamps, various lamps capable of instantaneously irradiating strong light energy, such as xenon lamps and LED lamps, can be used to form the planar beam PB and modify the glass substrate GS.

[0069] The strength of the wire harness LB or planar bundle PB can decrease in the direction from the center of the bendable region BA toward the boundary between the bendable region BA and the flat regions FA1 and FA2 (e.g., as shown in the image). Figure 6The distribution shown is Gaussian (i.e., the beam intensity can be at its maximum at the center of the bendable region BA, and the beam intensity can decrease in both the +x-axis and -x-axis directions toward the boundary between the bendable region BA and the flat regions FA1 and FA2). Therefore, the modification depth of the glass substrate GS can decrease from the center of the bendable region BA toward the boundary between the bendable region BA and the flat regions FA1 and FA2. As a result, when etching the bendable region BA, the slope of the surface remains essentially constant before and after the boundary between the bendable region BA and the flat regions FA1 and FA2, allowing for the formation of a very smooth and uniform groove GV in the bendable region BA. Furthermore, because the beam intensity decreases in the direction toward the boundary between the bendable region BA and the flat regions FA1 and FA2, the gradient morphology can be stabilized at the boundary between the bendable region BA and the flat regions FA1 and FA2.

[0070] When the boundary between the flexible region BA and the flat regions FA1 and FA2 in the cover window is clear, the boundary can be easily observed if the slope change is significant before and after the boundary. However, in the implementation, when the flexible region BA is modified and etched, the cover window CW (reference) Figures 8 to 10 The thickness of the etched groove GV can be gradually varied around the boundary between the flexible region BA and the flat regions FA1 and FA2, and can prevent the boundary between the flat regions FA1 and FA2 and the flexible region BA from being observed (or at least minimize the visibility of the boundary). Furthermore, the depth of modification in the flexible region BA can be adjusted, and the shape of the groove GV formed by etching can be adjusted by appropriately customizing the energy distribution of the wire harness LB or planar wire harness PB, to further minimize the visibility of the boundary between the flexible region BA and the flat regions FA1 and FA2.

[0071] Figure 7 This is a schematic diagram of etching in the manufacturing method of the cover window according to the embodiment.

[0072] In the etching (S30) task, a glass substrate GS can be etched in the etching apparatus, and the flexible region BA of the glass substrate GS is modified through the pretreatment (S20) task. The etching apparatus may include a stage ST, a heating unit HU, a nozzle unit NU, a storage tank TN, etc.

[0073] The stage ST may have a plate shape (i.e., the stage ST may be planar). The heating unit HU may be positioned at the central portion of the stage ST. The heating unit HU may include heating elements arranged and spaced apart from each other along a first direction (x-axis direction) and extending in a second direction (y-axis direction).

[0074] The nozzle unit NU may include nozzle heads HD arranged and spaced apart from each other along a first direction (x-axis direction) and extending in a second direction (y-axis direction). Within each nozzle head HD, nozzles NZ may be positioned at a predetermined distance from each other. The nozzles NZ may spray etchant in a direction toward the stage ST (e.g., downwards). The etchant may contain hydrofluoric acid (HF).

[0075] The storage tank TN can store etchant. The storage tank TN can be connected to the nozzle unit NU to provide or supply etchant to the nozzle unit NU.

[0076] The etching apparatus may also include a cleaning unit for removing residual etchant and impurities from the etched glass substrate GS and a drying unit for drying the cleaned glass substrate GS.

[0077] During the etching (S30) task, a pretreated glass substrate GS can be placed on the stage ST. In one or more embodiments, the flexible region BA of the glass substrate GS can be positioned to overlap with the heating unit HU. The center of the heating unit HU and the center of the flexible region BA can coincide in a first direction (x-axis direction) (i.e., the flexible region BA can be laterally centered relative to the heating unit HU).

[0078] When the stage ST is partially heated by the driving heating unit HU, the flexible region BA of the glass substrate GS that overlaps with the heating unit HU can also be heated. Therefore, the flexible region BA of the glass substrate GS can be heated to a higher temperature than the flat regions FA1 and FA2. Once the flexible region BA has been heated by the heating unit HU, the glass substrate GS can be etched by spraying etchant onto the glass substrate GS using the nozzle unit NU.

[0079] The heating unit HU can heat the bendable region BA such that the temperature decreases from the center of the bendable region BA towards the boundary between the bendable region BA and the flat regions FA1 and FA2 (i.e., the temperature of the glass substrate GS can be at its maximum at the center of the bendable region BA, and this temperature can decrease in both the +x-axis and -x-axis directions towards the boundary between the bendable region BA and the flat regions FA1 and FA2). For example, the heat applied to the bendable region BA by the heating unit HU can have a Gaussian or Lorentz distribution relative to the centerline of the bendable region BA.

[0080] Because the temperature of the flexible region BA of the glass substrate GS is higher than that of the flat regions FA1 and FA2, the etching rate of the flexible region BA (in the etching (S30) task) can be faster than that of the flat regions FA1 and FA2. Furthermore, since the flexible region BA has been modified through the pretreatment (S20) task, it can be etched more quickly than the flat regions FA1 and FA2. The etching selectivity of the flexible region BA relative to the flat regions FA1 and FA2 can be further increased by selectively pretreating and selectively heating the flexible region BA. In one or more embodiments, the thickness of the flat regions FA1 and FA2 can be reduced to the desired thickness in a single etching (S30) task, and a groove GV can be formed in the flexible region BA.

[0081] Etching is suitable for mass production and can be a machining method with low deviations in the external dimensions of each product. Therefore, the cover window CW manufactured by etching can result in the formation of a uniform stress distribution when the display device is folded. In terms of the structure of the display device, the stress distribution can cause stress concentration in the same area, and thus improve the reliability of the display device against damage.

[0082] In the etching (S30) task, the parameters of the etching process can be controlled by adjusting design parameters such as the spacing between nozzle heads HD, the spacing between nozzles NZ, the distance between nozzles NZ and glass substrate GS, and / or by adjusting optional variables such as the spray angle, time, concentration, flow rate and temperature of the etchant.

[0083] Figure 8 This is a perspective view of the task of attaching the display panel (S50) in the method of manufacturing a display device according to the embodiment.

[0084] As described above, a glass substrate GS can be provided as a cover window CW. The flexible region BA of the glass substrate GS is thinned through pretreatment (S20) and etching (S30) after pretreatment (S20). A display panel DP can be attached to the cover window CW, and the display panel DP can be a light-emitting display panel. Figure 8 As shown, the cover window CW can be attached to the display panel DP such that the recess GV faces the display panel DP. The cover window CW and the display panel DP can be bonded to each other by an adhesive member AM, and the recess GV can be filled with the adhesive member AM. The adhesive member AM can include optically clear adhesive (OCA), optically clear resin (OCR), pressure-sensitive adhesive (PSA), etc.

[0085] The adhesive component AM can have the same or nearly the same refractive index as the cover window CW. Therefore, the image displayed by the display panel DP is not distorted by the cover window CW and the adhesive component AM. That is, by filling the groove GV with the adhesive component AM, whose refractive index is the same or nearly the same as the cover window CW, light refraction is prevented, which could otherwise distort the image displayed by the display panel DP. Furthermore, the adhesive component AM can prevent or at least mitigate the ingress of moisture or other foreign matter into the groove GV, which can prevent crack growth in the groove GV and increase resistance to damage caused by long-term fatigue.

[0086] Figure 9 This is a perspective view of the task of attaching the display panel (S50) in the method of manufacturing a display device according to the embodiment, and Figure 10 yes Figure 9 The cross-sectional view of the display device shown is taken along a first direction.

[0087] Reference Figure 9 The display panel DP can be attached such that the recess GV of the cover window CW does not face the display panel DP (i.e., the recess GV of the cover window CW faces away from the display panel DP). In other words, the cover window CW and the display panel DP can be attached so that the recess GV is exposed to the outside of the display device. An adhesive member AM can be provided between the cover window CW and the display panel DP; the adhesive member AM can include OC, OCR, PSA, etc. Because the recess GV is exposed to the outside of the display device, the image displayed by the display panel DP can be refracted by the recess GV.

[0088] Reference Figure 10In the display device, a groove GV is formed on the upper surface of the cover window CW. The groove surface forming the groove GV may have a radius of curvature defined in a plane perpendicular to the second direction (y-axis direction) (i.e., the groove GV may have a series of radii of curvature in the zx plane). One end and the other end of the groove surface forming the groove GV may correspond to the boundary between the flexible region BA and the first flat region FA1, and the boundary between the flexible region BA and the second flat region FA2, respectively. One end and the other end of the groove surface forming the groove GV may be formed to have the minimum radius of curvature r among the radii of curvature of the groove surface. At least one internal point between one end and the other end of the groove surface may be formed to have the minimum radius of curvature r among the radii of curvature of the groove surface. Because the groove surface has the minimum radius of curvature r at one end and the other end, the groove surface forms a groove GV with a gentle slope (i.e., the groove surface is formed such that there is a gentle transition between the groove GV and the first flat region FA1 and the second flat region FA2). When the slope of the groove surface of the groove GV is gentle, the angle between the incident light and the groove surface is closer to 90 degrees. Therefore, the refraction of light is minimized or at least reduced, making the image distortion of the image displayed by the display panel DP not visually recognizable or perceptible. The minimum radius of curvature r at one end and the other end of the groove surface can be greater than a predetermined value (e.g., about 1 m or more), and therefore one end and the other end of the groove surface are not visually recognizable or perceptible.

[0089] To form one end and the other end of the grooved surface with a predetermined radius of curvature (e.g., the minimum radius of curvature r described above), conventional methods may involve mechanical treatments such as polishing or sandblasting and / or heat treatments such as hot pressing. However, in the case of mechanical or heat treatment, precise dimensional control can be difficult, and fine cracks may increase and degrade strength and optical properties (e.g., causing blurring). Furthermore, dimensional errors may occur for each product, resulting in uneven stress distribution for each product and potentially increased stress distribution.

[0090] According to one or more embodiments, the bendable region BA of the glass substrate GS is modified by performing pretreatment (S20) using a wire harness or planar beam without performing the aforementioned mechanical or thermal treatment, and then the bendable region BA of the glass substrate GS is etched (S30), such that a groove GV with a predetermined radius of curvature (e.g., the minimum radius of curvature r described above) can be formed at one end and the other end of the groove surface. Therefore, problems that may occur during mechanical or thermal treatment can be prevented or resolved, and processing time can be shortened because conventional mechanical or thermal treatment is not performed. Furthermore, since the deviation in the external dimensions of each product is low, a uniform or substantially uniform stress distribution can be achieved when the display device is folded. In terms of the structure of the display device, a uniform or substantially uniform stress distribution can cause stress concentration in the same area, which can improve the reliability of the display device against damage or failure.

[0091] The focus will now be on the display area DA to describe the configuration of the display panel DP that may be included in a display device according to one embodiment.

[0092] Figure 11 This is a schematic cross-sectional view of the layered structure of a display panel according to one embodiment. Figure 11 The cross-section shown can correspond to an approximate pixel area.

[0093] In addition to other components, the display panel DP also includes a substrate SB, transistors TR formed on the substrate SB, and light-emitting diodes (LEDs) connected to the transistors TR. The LEDs may correspond to pixels.

[0094] The substrate SB can be a flexible substrate made of polymers such as polyimide, polyamide and / or polyethylene terephthalate.

[0095] A barrier layer BR, which prevents moisture, oxygen, and other substances from penetrating from the substrate SB, can be disposed on the substrate SB. The barrier layer BR may include materials such as silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0096] A buffer layer BL can be disposed on the barrier layer BR. The buffer layer BL may include materials such as silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0097] The semiconductor layer AL of the transistor TR can be disposed on the buffer layer BL. The semiconductor layer AL may include a source region, a drain region, and a channel region between the source and drain regions. The semiconductor layer AL may include any of amorphous silicon, polycrystalline silicon, and oxide semiconductors. For example, the semiconductor layer AL may include low-temperature polycrystalline silicon (LTPS), or an oxide semiconductor material including at least one of zinc (Zn), indium (In), gallium (Ga), and tin (Sn). For example, the semiconductor layer AL may include indium gallium zinc oxide (IGZO).

[0098] The first insulating layer IN1 can be disposed on the semiconductor layer AL. The first insulating layer IN1 can include, for example, silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0099] The first gate conductive layer may be disposed on the first insulating layer IN1. The first gate conductive layer may include the gate line GL, the gate electrode GE of the transistor TR, and the first electrode C1 of the capacitor CS. The first gate conductive layer may include molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), etc., and may be formed by a single layer or multiple layers.

[0100] The second insulating layer IN2 can be disposed on the first gate conductive layer. The second insulating layer IN2 may include, for example, silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be single-layer or multi-layer.

[0101] The second gate conductive layer can be disposed on the second insulating layer IN2, and the second gate conductive layer can include the second electrode C2 of the capacitor CS. The second gate conductive layer can include molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), etc., and can be formed by a single layer or multiple layers.

[0102] The third insulating layer IN3 can be disposed on the second insulating layer IN2 and the second gate conductive layer. The third insulating layer IN3 may include materials such as silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0103] The first data conductive layer can be disposed on the third insulating layer IN3. The first data conductive layer can include the data line DL and the source electrode SE and drain electrode DE of the transistor TR. The source electrode SE and drain electrode DE can be connected to the source region and drain region of the semiconductor layer AL through contact holes in the insulating layers IN1, IN2 and IN3, respectively. The first data conductive layer can include aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), nickel (Ni), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), copper (Cu), etc., and can be formed by a single layer or multiple layers.

[0104] The fourth insulating layer IN4 may be disposed on the first data conductive layer. The fourth insulating layer IN4 may be an organic layer. For example, the fourth insulating layer IN4 may include organic insulating materials, such as general polymers (such as poly(methyl methacrylate) or polystyrene), polymer derivatives having phenolic groups, acrylic acid-based polymers, imide polymers, polyimides, siloxane-based polymers, etc.

[0105] The second data conductive layer can be disposed on the fourth insulating layer IN4. The second data conductive layer may include the drive voltage line DVL, the connection electrode LE, etc. The connection electrode LE can be connected to the drain electrode DE through the contact hole of the fourth insulating layer IN4. The second data conductive layer may include aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), nickel (Ni), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), copper (Cu), etc., and may be formed as a single layer or multiple layers.

[0106] The fifth insulating layer IN5 may be disposed on the second data conductive layer. The fifth insulating layer IN5 may be an organic layer. For example, the fifth insulating layer IN5 may include organic insulating materials, such as general polymers (such as poly(methyl methacrylate) or polystyrene), polymer derivatives having phenolic groups, acrylic acid-based polymers, imide polymers, polyimides, siloxane-based polymers, etc.

[0107] The first electrode E1 of the light-emitting diode (LED) can be disposed on the fifth insulating layer IN5. The first electrode E1 can be referred to as the pixel electrode. The first electrode E1 can be connected to the connection electrode LE through a contact hole in the fifth insulating layer IN5. Therefore, the first electrode E1 is electrically connected to the drain electrode DE, and thus can receive data signals controlling the brightness of the LED. The transistor TR connected to the first electrode E1 can be a driving transistor or a transistor electrically connected to the driving transistor. The first electrode E1 can be formed of a reflective conductive material or a semi-transparent / semi-reflective conductive material, or it can be formed of a transparent conductive material. The first electrode E1 can include transparent conductive materials such as indium tin oxide (ITO) or indium zinc oxide (IZO). The first electrode E1 can include metals or metal alloys such as lithium (Li), calcium (Ca), aluminum (Al), silver (Ag), magnesium (Mg), and / or gold (Au).

[0108] A sixth insulating layer IN6 may be disposed on the fifth insulating layer IN5. The sixth insulating layer IN6 may be referred to as a pixel defining layer or separator, and may have an opening overlapping the first electrode E1. The fifth insulating layer IN5 may comprise an organic insulating material such as an acrylic-based polymer or an imide-based polymer.

[0109] The emitter layer EL can be disposed on the first electrode E1. In addition to the emitter layer EL, at least one of the following can be disposed on the first electrode E1: hole injection layer (HIL), hole transport layer (HTL), electron transport layer (ETL), and electron injection layer (EIL).

[0110] The second electrode E2 can be disposed on the emitter layer EL. The second electrode E2 can be referred to as the common electrode. The second electrode E2 is made of a metal or metal alloy with a low work function (such as calcium (Ca), barium (Ba), magnesium (Mg), aluminum (Al), and / or silver (Ag)), and therefore has transmittance. The second electrode E2 can include a transparent conductive oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0111] Each pixel PX (reference) Figure 1A and Figure 1C The first electrode E1, the emitter layer EL, and the second electrode E2 form a light-emitting diode (LED) such as an organic light-emitting diode (OLED). The first electrode E1 can be the anode of the LED, and the second electrode E2 can be the cathode of the LED.

[0112] The encapsulation layer EN can be disposed on the second electrode E2. The encapsulation layer EN can prevent or at least mitigate the penetration of moisture or oxygen from the outside by encapsulating the light-emitting diode (LED). The encapsulation layer EN can be a thin-film encapsulation layer comprising at least one inorganic layer and at least one organic layer.

[0113] The buffer layer TBL can be disposed on the encapsulation layer EN. The buffer layer TBL may include materials such as silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0114] A touch sensor layer, including touch electrodes TE, can be disposed on a buffer layer TBL. The touch electrodes TE can have a mesh shape with openings that overlap with light-emitting diodes (LEDs).

[0115] A seventh insulating layer IN7 covering the touch electrode TE can be disposed on the touch sensor layer. The seventh insulating layer IN7 may include materials such as silicon nitride (SiN). x ), silicon oxide (SiO) x ) and / or silicon nitride oxide (SiO) x N y Inorganic insulating materials, which can be formed from a single layer or multiple layers.

[0116] An anti-reflective layer AR can be disposed on the seventh insulating layer IN7 to reduce the reflection of external light. The anti-reflective layer AR may include a polarizing layer. The anti-reflective layer AR can be formed on the seventh insulating layer IN7 or attached to the seventh insulating layer IN7 by an adhesive. The encapsulation layer EN, the touch sensor layer, and / or the seventh insulating layer IN7 can be formed as a refractive index-matching structure in place of the anti-reflective layer AR to achieve the anti-reflective effect.

[0117] A protective film PF used to protect the display panel DP can be disposed under the substrate SB. The protective film PF can be made of polymers such as polyethylene terephthalate, polyethylene naphthalate, or polyimide.

[0118] A functional sheet FS, including at least one of a gasket layer, a heat sink, a light shield, a waterproof strip, and an electron blocking film, can be disposed below the protective film PF.

[0119] Although the inventive concept has been described in conjunction with what is now considered to be practical embodiments, it should be understood that the inventive concept is not limited to the disclosed embodiments. Rather, the inventive concept is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for manufacturing a cover window for a display device, the method comprising: Provides a glass substrate that includes both flexible and flat regions; The flexible region is modified by irradiating the glass substrate with a beam; as well as The flexible region is etched to make it thinner than the flat region, wherein, during the etching of the flexible region, a groove is formed in the flexible region and a gradual transition is formed between the groove and the flat region. The step of irradiating the glass substrate with a beam includes guiding the beam through a plurality of reflectors and a plurality of lenses located between two adjacent reflectors, and irradiating the glass substrate in a beam manner. The wire harness has an intensity that decreases continuously from the center of the bendable region toward the boundary between the bendable region and the flat region.

2. The method for manufacturing a cover window for a display device according to claim 1, wherein, The beam is a laser beam.

3. The method for manufacturing a cover window for a display device according to claim 1, wherein, During the modification of the flexible region, the modification depth of the glass substrate decreases from the center of the flexible region toward the boundary between the flexible region and the flat region.

4. The method for manufacturing a cover window for a display device according to claim 1, wherein, Because of the modification of the flexible region, the flexible region is etched faster than the flat region during the etching process.

5. The method for manufacturing a cover window for a display device according to claim 1, wherein, The etching of the flexible region further includes heating the flexible region to a higher temperature than the flat region.

6. The method of manufacturing a cover window for a display device according to claim 5, wherein, During the heating process, the temperature applied to the bendable region has a Gaussian distribution relative to the centerline of the bendable region.

7. The method for manufacturing a cover window for a display device according to claim 1, wherein, The groove has a depth that decreases from the center of the flexible region toward the boundary between the flexible region and the flat region.

8. A method for manufacturing a flexible display device, the method comprising: Provides a glass substrate that includes both flexible and flat regions; The flexible region of the glass substrate is irradiated at least by a beam; Etching the glass substrate, wherein, during the etching of the glass substrate, a groove is formed in the flexible region and a gradual transition is formed between the groove and the flat region, and wherein the flexible region is etched faster than the flat region; and The display panel is attached to the glass substrate to form the flexible display device. The step of irradiating at least the flexible region of the glass substrate with a beam includes guiding the beam through a plurality of mirrors and a plurality of lenses located between two adjacent mirrors, and irradiating the flexible region of the glass substrate in a beam manner. The wire harness has an intensity that decreases continuously from the center of the bendable region toward the boundary between the bendable region and the flat region.

9. The method for manufacturing a flexible display device according to claim 8, wherein, The beam is a laser beam.

10. The method for manufacturing a flexible display device according to claim 8, wherein, During the irradiation with the beam, the glass substrate is modified to have a modified depth that decreases from the center of the flexible region toward the boundary between the flexible region and the flat region.

11. The method for manufacturing a flexible display device according to claim 8, wherein, Because the flexible region is irradiated with the beam, it is etched faster than the flat region when the glass substrate is etched.

12. The method for manufacturing a flexible display device according to claim 8, wherein, The etching of the glass substrate further includes heating the flexible region to a higher temperature than the flat region.

13. The method for manufacturing a flexible display device according to claim 12, wherein, During the heating process, the temperature applied to the bendable region has a Gaussian distribution relative to the centerline of the bendable region.

14. The method for manufacturing a flexible display device according to claim 8, wherein, The flexible region has a groove surface forming the groove, the groove surface having a plurality of radii of curvature, and one end and the other end of the groove surface each having the smallest of the plurality of radii of curvature.

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