Display device with touch panel

Abstract

A display device includes a display panel and a touch panel, the display panel including: a first surface including a display area configured to display an image; and a second surface arranged on an opposite side of the display panel from the first surface, the touch panel being arranged on the first surface and including a sensing electrode unit arranged on the first surface, wherein at least a portion of each of the display panel and the touch panel is bendable so that the center of curvature of the display panel and the touch panel is located outside the second surface, and wherein the sensing electrode unit is configured to be applied with a compressive force when the display device is bent.

Description

[0001] This application is a divisional application of a patent application filed on July 9, 2015, with application number 201510400386.X and titled “Flexible display device with touch panel”. Technical Field

[0002] Exemplary embodiments of the inventive concept relate to a flexible display device, and more particularly, to a flexible display device including a capacitive type external touch panel. Background Art

[0003] A touch panel provided on a display device provides a touch sensing function that facilitates interaction with a user. When a user approaches or contacts a surface of the display device using a user's finger or a touch pen, the touch sensing function extracts contact information, for example, sensing the location of the touched or touched surface. The display device may receive an image signal based on the contact information to display a corresponding image.

[0004] A capacitive touch panel may include a sensing capacitor having a sensing electrode. A capacitive touch panel may determine whether a touch has been made and the location of the touched surface by sensing changes in the electrostatic capacitance of the sensing capacitor generated when a conductor (such as a user's finger) approaches the touch panel. The sensing electrode may be formed of a transparent conductive layer such as indium tin oxide (ITO) and may be patterned on a transparent substrate.

[0005] The development of flexible display devices requires providing flexibility to touch panels. Therefore, touch panels including substrates formed of transparent plastic films have been developed. However, the transparent conductive layer used as a sensing electrode may have high transmittance and high conductivity, but low flexibility. In other words, although the transparent conductive layer may be thin, it will remain fragile.

[0006] Silver nanowires (AgNW), carbon nanotubes (CNTs), or graphene can be considered as electrode materials to replace the transparent conductive layer of the touch panel, but these materials have low optical properties (low light transmittance). At the same time, a technology of pre-forming a curved substrate of the touch panel and then attaching the sensing electrode to the curved surface of the substrate can also be considered. However, it may be difficult to pattern the sensing electrode to the curved surface of the substrate.

[0007] The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore the above information may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0008] Exemplary embodiments of the inventive concept provide a flexible display device capable of suppressing cracks of a transparent conductive layer caused by bending when the transparent conductive layer, such as indium tin oxide (ITO), is used as a sensing electrode of a touch panel.

[0009] Exemplary embodiments of the inventive concept also provide a flexible display device that can have a specific curved shape or can be repeatedly folded and includes a touch panel manufactured by patterning a sensing electrode on a flat substrate.

[0010] Additional aspects of the inventive concepts will be set forth in the detailed description which follows, and in part will be apparent from the disclosure, or may be learned by practice of the inventive concepts.

[0011] An exemplary embodiment of the inventive concept provides a flexible display device, the flexible display device comprising a display panel and a touch panel, the display panel comprising: a first surface comprising a display area configured to display an image; and a second surface disposed on a side of the display panel opposite to the first surface, and a touch panel disposed on the first surface, the touch panel comprising a base film and a transparent conductive layer disposed on a surface of the base film facing the display panel, wherein at least a portion of each of the display panel and the touch panel is bendable so that a center of curvature of the display panel and the touch panel is located outside the second surface.

[0012] The flexible display device may further include: a sensing electrode unit disposed on the base film; and a functional coating layer covering the transparent conductive layer and the sensing electrode unit, wherein the functional coating layer may be configured to generate an anchoring effect with the sensing electrode unit.

[0013] The functional coating layer may include an acrylic resin or a polyurethane resin, and a thickness of the functional coating layer may be in a range of 0.1 μm to 30 μm.

[0014] The functional coating layer may have a refractive index in the range of 1.3 to 2.0.

[0015] The functional coating layer may be covered by a protective film. The protective film may include at least one of polyethylene terephthalate (PET), cycloolefin polymer (COP), triacetyl cellulose (TAC), and polycarbonate (PC).

[0016] Another exemplary embodiment of the inventive concept provides a flexible display device, the flexible display device including a display panel and a touch panel, the display panel including: a first surface including a display area configured to display an image; and a second surface disposed on a side of the display panel opposite to the first surface, and a touch panel disposed on the first surface, the touch panel including: a base film; and a sensing electrode unit including a transparent conductive layer disposed on the base film, wherein the sensing electrode unit includes a first sensing electrode extending along a first direction and a second sensing electrode disposed along a second direction perpendicular to the first direction, at least one of the first sensing electrode and the second sensing electrode is disposed on a surface of the base film facing the display panel, and at least a portion of each of the display panel and the touch panel is bendable so that a center of curvature of the display panel and the touch panel is located outside the second surface.

[0017] The first sensing electrode and the second sensing electrode may be disposed on a surface of the base film facing the display panel, and the first sensing electrode may be insulated from the second sensing electrode by an insulating layer.

[0018] The first sensing electrode and the second sensing electrode may be covered by a functional coating layer, and the functional coating layer may be covered by a protective film.

[0019] The touch panel may include a first base film and a second base film stacked on each other, the first sensing electrode may be provided on a surface of the first base film facing the display panel, and the second sensing electrode may be provided on a surface of the second base film facing the display panel.

[0020] The first sensing electrode may be covered by a first functional coating layer, and the second sensing electrode may be covered by a second functional coating layer.

[0021] The second functional coating layer may be disposed closer to the display panel than the first functional coating layer, and the second functional coating layer may be covered by a protective film.

[0022] The touch panel may include a first base film and a second base film stacked on each other, the first sensing electrode may be provided on a surface of the first base film facing the display panel, the second base film may be provided closer to the display panel than the first base film, and the second sensing electrode may be provided on a surface of the second base film facing the first base film.

[0023] The first sensing electrode may be covered by a first functional coating layer, and the second sensing electrode may be covered by a second functional coating layer.

[0024] Another exemplary embodiment of the inventive concept provides a flexible display device, the flexible display device comprising a display panel, a touch panel, and a cover window disposed on the touch panel. The display panel comprises: a first surface, comprising a display area configured to display an image; and a second surface, disposed on a side of the display panel opposite to the first surface. A touch panel disposed on the first surface, the touch panel comprising: a base film; and a sensing electrode unit comprising a transparent conductive layer. The sensing electrode unit comprises a first sensing electrode disposed on a surface of the cover window facing the base film and a second sensing electrode disposed on a surface of the base film facing the display panel. At least a portion of each of the display panel, the touch panel, and the cover window is bendable so that their center of curvature is located outside the second surface.

[0025] The first sensing electrode may be covered by a first functional coating layer, the second sensing electrode may be covered by a second functional coating layer, and the second functional coating layer may be covered by a protective film.

[0026] According to an exemplary embodiment of the inventive concept, the stress applied to the transparent conductive layer of the touch panel can be reduced, thereby suppressing the generation of cracks in the transparent conductive layer and improving the folding resistance. In addition, the touch panel according to the exemplary embodiment may not require changing the existing manufacturing process and electrode materials of the touch panel, and thus can be easily manufactured by using the same process.

[0027] The foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the inventive concept and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate exemplary embodiments of the inventive concept and together with the description serve to explain the principles of the inventive concept.

[0029] Figure 1 is a schematic cross-sectional view illustrating a flexible display device according to an exemplary embodiment of the inventive concept.

[0030] Figures 2 to 4 They are Figure 1 Schematic cross-sectional view of a variation of the flexible display device shown in FIG.

[0031] Figure 5 It is shown Figure 1 0014 is a block diagram of a display panel and a touch panel of a flexible display device shown in FIG.

[0032] Figure 6 It is shown Figure 1A bottom view of a touch panel of a flexible display device is shown in FIG.

[0033] Figure 7 yes Figure 6 A partial enlarged view of .

[0034] Figure 8 It is along Figure 6 A cross-sectional view taken along line II-II.

[0035] Fig. 9 It is shown Figure 1 Schematic diagram of a touch panel of a flexible display device.

[0036] Fig.10 is a schematic diagram showing a touch panel according to a comparative example.

[0037] Fig.11 is a graph showing threshold strain of a transparent conductive layer according to tension and compression.

[0038] Fig.12 is a graph showing stress according to the radius of curvature of the transparent conductive layer.

[0039] Fig.13 is a cross-sectional view of a touch panel of a flexible display device according to an exemplary embodiment of the inventive concept.

[0040] Fig.14 is a cross-sectional view of a touch panel of a flexible display device according to an exemplary embodiment of the inventive concept.

[0041] Fig.15 is a cross-sectional view of a touch panel of a flexible display device according to an exemplary embodiment of the inventive concept.

[0042] Fig.16 is a cross-sectional view of a touch panel of a flexible display device according to an exemplary embodiment of the inventive concept.

[0043] Fig.17 is a cross-sectional view of a touch panel of a flexible display device according to an exemplary embodiment of the inventive concept. DETAILED DESCRIPTION

[0044] In the following description, for the purpose of explanation, numerous specific details are set forth to provide a thorough understanding of various exemplary embodiments. However, it is apparent that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other examples, well-known structures and devices are shown in block diagram form to avoid unnecessarily obscuring various exemplary embodiments.

[0045] In the drawings, the size and relative sizes of layers, films, panels, regions, etc. may be exaggerated for clarity and descriptive purposes. Additionally, like reference numerals designate like elements.

[0046] When an element or layer is referred to as being "on" another element or layer, "connected to" or "bonded to" another element or layer, the element or layer may be directly on, connected to or bonded to the other element or layer, or there may be an intermediate element or intermediate layer. However, when an element or layer is referred to as being "directly on" another element or layer, "directly connected to" or "directly bonded to" another element or layer, there may be no intermediate element or intermediate layer. For the purposes of this disclosure, "at least one (kind) of X, Y, and Z" and "at least one (kind) of selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, for example, XYZ, XYY, YZ, and ZZ. The same reference numerals always indicate the same element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] Although the terms first, second, etc. can be used to describe various elements, components, regions, layers and / or parts here, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer and / or part from another element, component, region, layer and / or part. Therefore, without departing from the teaching of the present disclosure, the first element, first component, first region, first layer and / or first part discussed below can be referred to as the second element, second component, second region, second layer and / or second part.

[0048] For descriptive purposes, spatially relative terms such as "under," "below," "below," "above," "on," and the like may be used herein to describe the relationship of one element or feature to another element or feature as shown in the accompanying drawings. In addition to the orientations depicted in the accompanying drawings, spatially relative terms are intended to encompass different orientations of the device when in use, operation, and / or manufacture. For example, if the device in the accompanying drawings is flipped, an element described as "below" or "below" the other element or feature will subsequently be positioned as "above" the other element or feature. Thus, the exemplary term "below" may include both "above" and "below." In addition, the device may be positioned otherwise (e.g., rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein interpreted accordingly.

[0049] The predicates used herein are for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, the singular forms "one", "a (kind)" and "the (said)" are also intended to include plural forms, unless the context clearly indicates otherwise. Furthermore, when the term "includes" and / or its variations or "comprising" and / or its variations are used in this specification, it means that there are stated features, wholes, steps, operations, elements, components and / or their groups, but it does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their groups.

[0050] Here, various exemplary embodiments are described with reference to cross-sectional views as schematic diagrams of idealized exemplary embodiments and / or intermediate structures. As such, variations in the shapes of the diagrams, such as those caused by manufacturing techniques and / or tolerances, are expected. Therefore, the exemplary embodiments disclosed herein should not be interpreted as being limited to the specific illustrated shapes of the regions, but are intended to include deviations in shape caused by, for example, manufacturing. For example, an implanted region shown as a rectangle will typically have rounded or curved features and / or a gradient of implant concentration at its edges, rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation occurs. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of the regions of the device, and are not intended to be limiting.

[0051] Unless otherwise defined, the terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as they have in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0052] Figure 1 is a schematic cross-sectional view illustrating a flexible display device 100 according to an exemplary embodiment of the inventive concept.

[0053] Reference Figure 1 According to the first exemplary embodiment, the flexible display device 100 includes a display panel 10 and a touch panel 20 disposed on the display panel 10. The display panel 10 includes a display area ( Figure 5 The touch panel 20 is provided on the first surface 11 to cover the display area.

[0054] The flexible display device 100 may further include a polarization member 30 disposed between the display panel 10 and the touch panel 20 and a cover window 40 disposed on the touch panel 20. The polarization member 30 may be formed by a combination of a linear polarizer and a quarter wave plate and may suppress reflection of external light. The touch panel 20 may be adhered to the polarization member 30 by a first transparent adhesive layer 51, and the cover window 40 may be attached to the touch panel 20 by a second transparent adhesive layer 52.

[0055] Each of the display panel 10, the polarization member 30, the touch panel 20, and the cover window 40 may be formed of a flexible plastic film as a base member, thereby having a flexible property that can be bent by an external force. Figure 1 , the flexible display device 100 is shown to have a stacked structure of a display panel 10, a polarization member 30, a touch panel 20, and a cover window 40. However, the positions of the polarization member 30 and the touch panel 20 may be changed.

[0056] The flexible display device 100 is formed to have a single curvature over its entire portion, so that it is bendable. In this case, the center of curvature is located outside the second surface 12 of the display panel 10. That is, the center of curvature is the end point of the radius line extending from the curved display panel 10. As a result, the screen of the flexible display device 100 is convexly bendable relative to the user. The flexible display device 100 can remain in a bent state statically, or can repeatedly reach a bent state and a planar state. In the case of repeatedly reaching a bent state and a planar state, the flexible display device 100 can be described as having a foldable or bendable function.

[0057] The flexible display device 100 may include Figure 1 Various bending shapes are shown in the bending shapes. Figures 2 to 4 yes Figure 1 Schematic cross-sectional views of various exemplary variations of the flexible display device 100 are shown in FIG. Figures 2 to 4 , each of the flexible display devices 110 , 120 , and 130 is briefly illustrated as having a display panel 10 , a polarization member 30 , a touch panel 20 , and a cover window 40 .

[0058] Reference Figure 2 , the flexible display device 110 according to the exemplary embodiment includes a flat portion FA and first and second curved portions CA1 and CA2 respectively disposed at opposite sides of the flat portion FA. The centers of curvature of the first and second curved portions CA1 and CA2 are located outside the second surface 12 of the display panel 10. The radius of curvature of the first curved portion CA1 may be set to be the same as or different from the radius of curvature of the second curved portion CA2.

[0059] Reference Figure 3 , a flexible display device 120 according to another exemplary embodiment includes a curved portion CA and a first flat portion FA1 and a second flat portion FA2 respectively disposed at opposite sides of the curved portion CA. The center of curvature of the curved portion CA is located outside the second surface 12 of the display panel 10. The width of the first flat portion FA1 may be set to be the same as or different from the width of the second flat portion FA2.

[0060] Reference Figure 4 According to another exemplary embodiment, the flexible display device 130 is bent in a ring shape so that its opposite ends are folded around each other or parts of the opposite ends overlap each other. In this case, the center of curvature is located outside the second surface 12. Figures 1 to 4 In all the exemplary embodiments shown in FIG. 1 , the flexible display devices 100 , 110 , 120 , and 130 may remain stationary in a bent state, or may repeatedly achieve a bent state and a planar state.

[0061] exist Figures 1 to 4 Various bending shapes that can be realized by the flexible display device are shown in FIG. 1 , but the bending shape of the flexible display device is not limited thereto. Figures 1 to 4 In all the exemplary embodiments shown in FIG. 1 , at least a portion of each of the flexible display devices 100 , 110 , 120 , and 130 is bendable, and the center of curvature thereof is located outside the second surface 12 .

[0062] Figure 5 It is shown Figure 1 1 is a block diagram of a display panel 10 and a touch panel 20 of a flexible display device 100 shown in FIG.

[0063] Reference Figure 5 The display area DA on which an image can be displayed is disposed on the first surface 11 of the display panel 10. The display panel 10 may be a flat display panel such as an organic light emitting diode (OLED) device, a liquid crystal display (LCD), or an electrophoretic display device. By using a plastic film such as polyimide as a substrate, the display panel 10 may have a flexible property that can be bent by an external force.

[0064] In the display area DA, a plurality of pixels PX, a plurality of gate lines (not shown) connected to the pixels PX to transmit driving signals, and a plurality of data lines (not shown) may be provided. In the case of an organic light emitting diode panel, each pixel PX may include a switching element (not shown) connected to the gate line and the data line, and a pixel electrode (not shown) connected to the switching element.

[0065] The switching element can be turned on or off according to the gate signal from the gate line to selectively send the data signal from the data line to the pixel electrode. The pixel PX may further include a common electrode (not shown) disposed opposite to the pixel electrode and an emission layer disposed between the pixel electrode and the common electrode to form a light emitting device. The gate line and the data line may extend to the peripheral area PA1 to form a pad portion (not shown).

[0066] The display controller 61 may receive an input signal including brightness information of each pixel PX and an input control signal for controlling the display thereof from an external device. The display controller 61 may convert the input image signal into an output image signal by processing the input image signal based on the input control signal, and may generate control signals such as a gate control signal and a data control signal. The display controller 61 may output the gate control signal to a gate driver (not shown), and may output the data control signal and the output image signal to a data driver (not shown).

[0067] The touch panel 20 includes a touch area TA having a sensing electrode unit 22 and a peripheral area PA2 outside the touch area TA. At the peripheral area PA2, a connection line (not shown) for connecting each of the first sensing electrode 23 and the second sensing electrode 24 to the touch controller 62 may be formed.

[0068] The touch area TA may sense a touch when an object actually approaches or contacts the flexible display device 100. Here, contact may include an external object (such as a user's finger) approaching the flexible display device 100, hovering while the external object approaches the flexible display device 100, or directly contacting the flexible display device 100. The area of ​​the touch area TA may be formed to be smaller than or equal to the area of ​​the display area DA.

[0069] The touch controller 62 may be connected to the sensing electrode unit 22 to control the operation of the touch panel 20. The touch controller 62 may send a sensing input signal to the sensing electrode unit 22, or may receive a sensing output signal to perform processing. The touch controller 62 may process the sensing output signal to generate contact information, wherein the contact information may include whether a touch is made and the position of the touched surface of the flexible display device 100. The touch panel 20 may be connected to the touch controller 62 and the display controller 61 so that their operations may be controlled.

[0070] Figure 6 yes Figure 1 FIG. 1 is a bottom view of the touch panel 20 of the flexible display device 100 shown in FIG. Figure 7 yes Figure 6 A partial enlarged view of Figure 8 It is along Figure 6For ease of description, Figures 6 to 8 , the touch panel is shown as a flat type.

[0071] Reference Figures 6 to 8 The touch panel 20 according to the present exemplary embodiment includes a transparent base film 21 and a sensing electrode unit 22 provided on a surface of the base film 21 facing the display panel 10. The base film 21 may be formed of a polymer film such as polyimide to provide the touch panel 20 with flexibility.

[0072] Sensing electrode unit 22 may include a plurality of first sensing electrodes 23 arranged in a first direction and a plurality of second sensing electrodes 24 arranged in a second direction while maintaining a state of being insulated from first sensing electrodes 23. Here, the first direction and the second direction may be perpendicular to each other so that first sensing electrodes 23 and second sensing electrodes 24 are arranged in a matrix form.

[0073] The first sensing electrode 23 may include a plurality of first sensing monomers 231 and a plurality of first connectors 232 for connecting the first sensing monomers 231. The second sensing electrode 24 may include a plurality of second sensing monomers 241 and a plurality of second connectors 242 for connecting the second sensing monomers 241. Each of the sensing monomers 231 and 241 has a quadrilateral shape. The first sensing monomer 231 and the second sensing monomer 241 are separated from each other to prevent them from being folded or overlapped with each other. The first connector 232 and the second connector 242 overlap each other, but an insulating layer 25 may be provided between them to prevent electrical connection.

[0074] According to the present exemplary embodiment, the sensing electrode unit 22 may be formed of a transparent conductive layer. The transparent conductive layer may include indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide (In 2 O 3 ) and at least one of zinc oxide (ZnO).

[0075] At the peripheral area PA2 located outside the touch area TA, a connection line 26 for connecting each of the first sensing electrode 23 and the second sensing electrode 24 to the touch controller 62 is formed. The connection line 26 may be formed of a low-resistance metal film such as molybdenum (Mo), silver (Ag), titanium (Ti), copper (Cu), and aluminum (Al), and a transparent conductive layer.

[0076] The touch controller 62 can sense the touch position by inputting a sensing input signal into at least one of the first sensing electrode 23 and the second sensing electrode 24 and receiving a sensing output signal. Methods for sensing the touch position may include a self-capacitance method and a mutual capacitance method. For example, in the self-capacitance method, the first sensing electrode 23 and the second sensing electrode 24 receive a sensing input signal. When a conductive object such as a finger or a touch pen contacts a specific area of ​​the touch area TA, the capacitance of the sensing electrode unit 22 in the area may change. Then, the touch controller 62 searches for the position of the first sensing electrode 23 or the second sensing electrode 24 where the capacitance change is sensed, and detects the position as the touch position.

[0077] The touch panel 20 can prevent cracks caused by bending by changing the position of the sensing electrode unit 22 while using a transparent conductive layer such as ITO as the sensing electrode unit 22. Specifically, the sensing electrode unit 22 is formed on the surface of the base film 21 facing the display panel 10, and is not formed on the surface of the base film 21 facing the cover window 40. In this case, at least a portion of the flexible display device 100 is bendable, and the center of curvature thereof is located outside the second surface 12 of the display panel 10.

[0078] Fig. 9 It is shown Figure 1 Schematic diagram of a touch panel 20 of a flexible display device 100. Fig.10 is a schematic diagram showing a touch panel 201 according to a comparative example.

[0079] like Fig. 9 As shown in FIG. 1 , in the touch panel 20 according to the present exemplary embodiment, the transparent conductive layer 27 is formed on the surface of the base film 21 facing the center of curvature of the touch panel 20. In contrast, Fig.10 As shown in FIG. 2 , in the touch panel 201 according to the comparative embodiment, the transparent conductive layer 271 may be formed on the surface of the base film 21 opposite to the center of curvature of the touch panel 201. As a result, a compressive force is applied to the transparent conductive layer 27 according to the present exemplary embodiment, and a tensile force is applied to the transparent conductive layer 271 according to the comparative embodiment.

[0080] Fig.11 is a graph showing threshold strain according to tension and compression of the transparent conductive layers 27 and 271 .

[0081] like Fig.11 As shown, in two transparent conductive layers of the same size and thickness, the threshold strain (1.1%) of the transparent conductive layer 271 to which tension is applied is smaller than the threshold strain (1.7%) of the transparent conductive layer 27 to which compression is applied. Therefore, the transparent conductive layer 27 to which compression is applied is stronger against external force than the transparent conductive layer 271 to which tension is applied.

[0082] Fig.12 is a graph showing stress according to the curvature radius of the transparent conductive layer 271. Here, the touch panel 20 according to the present exemplary embodiment (ie, the first embodiment) and the touch panel 201 according to the comparative embodiment both include the base film 21 having a thickness of 80 μm.

[0083] like Fig.12 As shown in FIG. 1 , under all conditions where the radius of curvature is within the range of 4 mm to 6 mm, less stress is applied to the transparent conductive layer 27 included in the touch panel 20 according to the present exemplary embodiment than in the touch panel 201 according to the comparative embodiment. Specifically, under the condition where the radius of curvature is 5 mm, the stress of the transparent conductive layer 27 included in the touch panel 20 according to the present exemplary embodiment is less than the stress of the transparent conductive layer 271 included in the touch panel 201 according to the comparative embodiment.

[0084] Thus, compared with the touch panel 201 according to the comparative embodiment, the touch panel 20 according to the present exemplary embodiment can more effectively suppress the generation of cracks in its transparent conductive layer 27 by reducing the stress of the transparent conductive layer 27, thereby improving the folding resistance. Therefore, the flexible display device 100 can improve the durability of the product by suppressing the occurrence of a failure of the touch panel 20 caused by folding.

[0085] The touch panel 20 according to the present exemplary embodiment may not need to change the existing manufacturing process and electrode material of the touch panel 20, and can be easily manufactured by using the existing manufacturing process. In addition, the flat base film 21 of the touch panel 20 according to the present exemplary embodiment can be patterned to have the sensing electrode unit 22 and the connecting line 26 as in the existing process, and can be easily attached to the display panel 10 by using the first transparent adhesive layer 51.

[0086] Fig.13 is a cross-sectional view of a touch panel 210 of a flexible display device according to an exemplary embodiment of the inventive concept. In the flexible display device according to the present exemplary embodiment, all constituent elements except the touch panel 210 are the same as those according to the embodiment of the present invention. Figure 1 The constituent elements in the flexible display device of the described exemplary embodiments are substantially similar, and repeated descriptions thereof are omitted.

[0087] Reference Fig.13According to the present exemplary embodiment, the touch panel 210 may further include a functional coating layer 28 covering the sensing electrode unit 22. The functional coating layer 28 may be formed of an acrylic resin or a polyurethane resin. The anchor effect generates a high surface bonding force between the surface of the sensing electrode unit 22 and the functional coating layer 28, thereby suppressing the generation of cracks. The anchor effect is a mechanical bonding that occurs when the functional coating layer 28 penetrates into an empty hole or a recessed area on the surface of the sensing electrode unit 22 and solidifies therein.

[0088] The functional coating layer 28 may be formed by using a liquid resin by using a wet coating method, or by stacking a dry film resin on the sensing electrode unit 22 and hardening the stacked resin. The functional coating layer 28 may be formed to have a thin thickness in the range of 0.1 μm to 30 μm, thereby minimizing an increase in the thickness of the touch panel 210 and a decrease in optical transparency. The functional coating layer 28 may be formed only on the touch area TA, or may be formed on the touch area TA and the peripheral area PA2.

[0089] In a general touch panel, the base film 21 may include an optical index matching layer that prevents the sensing electrode unit 22 from being seen. For example, when the sensing electrode unit 22 is formed of ITO, the base film 21 may include a silicon dioxide (SiO2) layer on its surface facing the sensing electrode unit 22. 2 ) of the optical index matching layer.

[0090] In the present exemplary embodiment, the touch panel 210 can use the functional coating layer 28 as an optical index matching layer by controlling the refractive index of the functional coating layer 28, so the conventional optical index matching layer can be omitted. The functional coating layer 28 may have a refractive index in the range of 1.3 to 2.0. When the functional coating layer 28 having a refractive index in the range of 1.3 to 2.0 is formed to have a thickness in the range of 0.1 μm to 30 μm, and the sensing electrode unit 22 is formed of ITO to have a thickness in the range of 10 nm to 200 nm, the sensing electrode unit 22 can be prevented from being seen.

[0091] Fig.14 is a cross-sectional view of a touch panel 220 of a flexible display device according to an exemplary embodiment of the inventive concept. In the flexible display device according to the present exemplary embodiment, all constituent elements except the touch panel 220 are the same as those according to the embodiment of the present invention. Figure 1 Constituent elements in the flexible display devices of the described exemplary embodiments are substantially similar, and repeated descriptions thereof are omitted.

[0092] Reference Fig.14The touch panel 220 according to the present exemplary embodiment further includes a functional coating layer 28 covering the sensing electrode unit 22 and a protective film 29 covering the functional coating layer 28. The functional coating layer 28 according to the present exemplary embodiment is similar to the above-mentioned Fig.13 The functional coating layers of the exemplary embodiments described are substantially similar.

[0093] The protective film 29 may block the transmission of moisture and chemicals, and may include polyethylene terephthalate (PET), cycloolefin polymer (COP), triacetyl cellulose (TAC), or polycarbonate (PC). The protective film 29 protects the sensing electrode unit 22 and the functional coating layer 28, thereby improving the chemical resistance and corrosion resistance of the touch panel 220. A transparent adhesive layer (not shown) may be provided between the functional coating layer 28 and the protective film 29.

[0094] In the flexible display device according to the exemplary embodiment of the inventive concept, the first sensing electrode 23 and the second sensing electrode 24 constituting the sensing electrode unit 22 are formed on the same surface. However, the first sensing electrode 23 and the second sensing electrode 24 may be formed on different surfaces. Figures 15 to 17 Describe this construction.

[0095] Fig.15 2 is a cross-sectional view of a touch panel 20 of a flexible display device 400 according to an exemplary embodiment of the inventive concept. The same elements will be designated by the same reference numerals as those in other exemplary embodiments.

[0096] Reference Fig.15 In the flexible display device 400 according to the present exemplary embodiment, the first sensing electrode 23 is formed on the surface of the cover window 40 facing the touch panel 20, and the second sensing electrode 24 is formed on the surface of the base film 21 facing the display panel 10. The positions of the first sensing electrode 23 and the second sensing electrode 24 may be changed. Specifically, the second sensing electrode 24 may be formed on the cover window 40, and the first sensing electrode 23 may be formed on the base film 21.

[0097] Since the first sensing electrode 23 and the second sensing electrode 24 are formed on different surfaces, an insulating layer for insulating the first sensing electrode 23 and the second sensing electrode 24 may not be provided. The first sensing electrode 23 formed on the cover window 40 may be covered by the first functional coating layer 281, and the second sensing electrode 24 formed on the base film 21 may be covered by the second functional coating layer 282. The material, thickness, and refractive index of the functional coating layers 281 and 282 are substantially similar to those in the exemplary embodiment described above, and repeated description thereof is omitted.

[0098] The second functional coating layer 282 may be covered by a protective film 29, and the first functional coating layer 281 may also be covered by a protective film (not shown). The material and function of the protective film 29 are substantially similar to those in the exemplary embodiment described above, and repeated description thereof is omitted.

[0099] Fig.16 is a cross-sectional view of a touch panel 20 of a flexible display device 500 according to an exemplary embodiment of the inventive concept. Fig.14 The same reference numerals are used throughout the described exemplary embodiments to designate the same elements.

[0100] Reference Fig.16 In the flexible display device 500 according to the present exemplary embodiment, the touch panel 20 includes a first base film 211 and a second base film 212 stacked on each other. The first sensing electrode 23 may be formed on a surface of the first base film 211 facing the display panel 10, and the second sensing electrode 24 may be formed on a surface of the second base film 212 facing the display panel 10.

[0101] The first sensing electrode 23 may be covered by the first functional coating layer 281, and the second sensing electrode 24 may be covered by the second functional coating layer 282. The material, thickness, and refractive index of the functional coating layers 281 and 282 are substantially similar to those described above with respect to Fig.13 The second functional coating layer 282 may be covered by a protective film 29. The material and function of the protective film 29 are substantially similar to those described above. Fig.14 The situation described above is omitted and its repeated description is omitted.

[0102] Fig.17 2 is a cross-sectional view of a touch panel 20 of a flexible display device 600 according to an exemplary embodiment of the inventive concept. The same elements will be designated by the same reference numerals as those described above.

[0103] Reference Fig.17 In the flexible display device 600 according to the present exemplary embodiment, the touch panel 20 includes a first base film 211 and a second base film 212 stacked on each other. The first sensing electrode 23 may be formed on a surface of the first base film 211 facing the display panel 10, and the second sensing electrode 24 may be formed on a surface of the second base film 212 facing the cover window 40.

[0104] The first sensing electrode 23 may be covered by the first functional coating layer 281, and the second sensing electrode 24 may be covered by the second functional coating layer 282. An adhesive layer (not shown) may be provided between the first functional coating layer 281 and the second functional coating layer 282. The material, thickness, and refractive index of the functional coating layers 281 and 282 are substantially similar to those described above with respect to Fig.13 The described situation and its repeated description is omitted.

[0105] For ease of description, Figures 15 to 17 In the figure, illustration of the first transparent adhesive layer for adhering the polarization member 30 and the touch panel 20 is omitted.

[0106] As described above, at least a portion of the flexible display device is bendable. Therefore, the center of curvature of the bent portion is located outside the second surface 12 of the display panel 10. In the touch panel 20, a transparent conductive layer may be formed on the surface of the base film 21 facing the display panel 10. The transparent conductive layer formed on the surface of the base film 21 facing the display panel 10 may include the first sensing electrode 23 and the second sensing electrode 24 or at least a portion thereof.

[0107] When bent, the transparent conductive layer formed on the surface of the base film 21 facing the display panel 10 can be subjected to compression rather than tension, thereby reducing stress and suppressing crack generation. In addition, the generation of cracks on the surface can be further suppressed by the high surface adhesion between the transparent conductive layer and the functional coating layer 28. In the flexible display device, the reliability and durability of the product can be improved by suppressing the functional degradation of the touch panel 20 caused by cracks in the transparent conductive layer.

[0108] While certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to these exemplary embodiments, but rather to the broader scope of the given claims and various obvious modifications and equivalent arrangements.

Claims

1. A display device, comprising: A display panel, the display panel comprising: a first surface including a display area configured to display an image; and a second surface disposed on an opposite side of the display panel from the first surface; a touch panel disposed on the first surface, the touch panel comprising a sensing electrode unit disposed on the first surface, the sensing electrode unit comprising a first sensing electrode and a second sensing electrode; and a functional coating layer disposed on the first surface and covering at least one of the first sensing electrode and the second sensing electrode, wherein at least a portion of each of the display panel and the touch panel is bendable so that the center of curvature of the display panel and the touch panel is located outside the second surface, wherein the sensing electrode unit is configured to be applied with a compressive force when the display device is bent, and The functional coating layer is configured to generate an anchoring effect with the sensing electrode unit.

2. The display device according to claim 1, wherein: The functional coating layer is disposed between the display panel and the sensing electrode unit.

3. The display device according to claim 1, wherein: The functional coating layer comprises acrylic resin or polyurethane resin; and The thickness of the functional coating layer is in the range of 0.1 μm to 30 μm.

4. The display device according to claim 1, wherein: The functional coating layer has a refractive index in the range of 1.3 to 2.

0. 5 . The display device according to claim 1 , further comprising a protective film covering the functional coating layer.

6. The display device according to claim 5, wherein: The protective film includes at least one of polyethylene terephthalate, cycloolefin polymer, cellulose triacetate, and polycarbonate.

7. The display device according to claim 1, wherein: The first sensing electrode and the second sensing electrode are formed on the same surface, and the first sensing electrode extends along a first direction and the second sensing electrode is disposed along a second direction perpendicular to the first direction.

8. The display device according to claim 7, wherein: The first sensing electrode is insulated from the second sensing electrode by an insulating layer.

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