Patent Publication Number: US-2023140335-A1

Title: Display device and electronic device having same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/141,059, filed Jan. 4, 2021, which is a continuation of U.S. application Ser. No. 16/726,417, filed on Dec. 24, 2019, now U.S. Pat. No. 10,908,647, which is a continuation of U.S. application Ser. No. 15/736,862, filed on Dec. 15, 2017, now U.S. Pat. No. 10,545,537, which is a national stage application of International Patent Application No. PCT/KR2016/005936, filed on Jun. 3, 2016, which designates the United States, which claims priority to Korean Patent Application 10-2015-0086734, filed on Jun. 18, 2015 and Korean Patent Application 10-2016-0068901, filed on Jun. 2, 2016. The contents of each of these applications are incorporated herein in their entirety. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates to an electronic device, and particularly, to a flexible display device and an electronic device including the same. 
     Description of Related Art 
     An electronic device is a device that performs a specific function according to a program provided therein, such as an electronic scheduler, a portable multimedia reproducer, a mobile communication terminal, a tablet PC, an image/sound device, a desktop/laptop PC, or a vehicular navigation system, as well as a home appliance. For example, such an electronic device may output information stored therein as sound or an image. As the degree of integration of such an electronic device has increased, and super-high speed and large-capacity wireless communication has become popular, various functions have recently been provided together in a single mobile communication terminal. For example, various functions, such as an entertainment function (e.g., a game function), a multimedia function (e.g., a music/video reproduction function), a communication and security function for mobile banking, a schedule management function, and an e-wallet function, are integrated in a single electronic device, in addition to a communication function. 
     Electronic devices are capable of outputting information, such as an image, text, and a video image by including a display device. Display device have been developed from a vacuum tube type to a flat plate type, and it has become possible to provide a larger screen as the volumes of household appliances, such as televisions, have been drastically reduced. Further, it has also become possible to provide high-quality image information through a miniaturized electronic device, such as a mobile communication terminal. 
     An electronic device, such as a mobile communication terminal, may be configured to be foldable so as to ensure portability. When a flexible display device is mounted on a foldable electronic device, the portability of the electronic device can be maintained or improved while providing a larger screen in an expanded state. 
     Such a display device may include a display element that outputs a screen and a window member that protects the display element. The window member may have sufficient strength to protect the display element from the external environment and sufficient transparency to transmit the screen output from the display element therethrough. Further, in order to prevent deterioration of image quality due to scratches or the like of the window member, the surface hardness of the window member may be strengthened by forming a hard coating layer on the surface of the window member using a ceramic, acryl, or the like. 
     SUMMARY 
     However, in a flexible display device, the window member also has flexibility, which may make it difficult to secure sufficient strength to protect the display device. For example, when a touch-screen function is incorporated in the display device, the user frequently touches the surface of the window member, and in the flexible display device, external pressure (e.g., contact pressure applied by the user) may be transferred to the display device. 
     It may be possible to prevent the contact pressure applied by the user from being transferred to the display element by, for example, increasing the thickness of the window member so that the mechanical strength of the window member can be increased. However, since the flexibility of the window member is deteriorated as the mechanical strength of the window member is increased, there is a limit in the extent to which the thickness of the window member in the flexible display device can be increased. 
     Therefore, various embodiments of the present disclosure provide a flexible display device which is capable of preventing external pressure from being transferred to a display element while ensuring the flexibility thereof, and provide an electronic device having the flexible display device. 
     In addition, various embodiments of the present disclosure provide a display device capable of outputting a screen of good quality while ensuring the flexibility and strength thereof, and provide an electronic device having the display device. 
     Disclosed in various embodiments of the present disclosure are a display device and an electronic device having the same, the display device including: a display element, at least a portion of which is deformable in a curved shape; and a flexible window member stacked on the display element. A portion of the window member is formed to have a thickness smaller than the thickness of a remaining portion of the window member. 
     The window member may include a stepped portion or a curved portion on at least one face thereof such that a portion, in which the stepped portion or the curved portion is formed, may be formed to be thinner than a remaining portion. 
     In some embodiments, the display device may include: 
     a display element, at least a portion of which is deformable in a curved shape; 
     a flexible window member stacked on the display element; and 
     a first film member laminated on at least one face of the window member. 
     When the window member is mounted on an electronic device, a portion having a reduced thickness may be disposed to correspond to a portion, which is deformed into a curved shape according to, for example, an opening/closing operation of the electronic device. Through this arrangement, the deformation of the window member according to the opening/closing operation of the electronic device can be smoothly performed. 
     The display device according to various embodiments of the present disclosure and the electronic device are able to secure flexibility by implementing a portion (e.g., a portion to be deformed into a curved shape) so as to have a thickness smaller than the other portions in configuring the window member that protects the display element. In configuring the display device described above, it is possible to prevent external pressure from being transferred to the display element by securing a sufficient thickness in a portion of the window member, other than the portion that is to be deformed into the curved shape. Further, in a display device according to various embodiments of the present disclosure and an electronic device having the display device, when a variation in the quality of an image, which has been transmitted through the window member due to the difference in thickness of the window member occurs, it is possible to output a screen of good quality by forming a reinforcing layer so as to compensate for the deviation in image quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating an electronic device including a display device according to various embodiments of the present disclosure; 
         FIG.  2    is a cross-sectional view illustrating the configuration of the electronic device including the display device according to various embodiments of the present disclosure; 
         FIG.  3    is a cross-sectional view illustrating the configuration of a conventional flexible display device in the state in which external pressure is applied thereto; 
         FIG.  4    is a cross-sectional view illustrating a configuration of a display device according to one of various embodiments of the present disclosure; 
         FIG.  5    is a view illustrating a window member of a display device according to one of various embodiments of the present disclosure; 
         FIG.  6    is a view illustrating various modifications of the window member of the display device according to one of various embodiments of the present disclosure; 
         FIG.  7    is a cross-sectional view illustrating the configuration of a display device according to another one of various embodiments of the present disclosure in order to explain the display device; 
         FIG.  8    is a cross-sectional view illustrating the configuration of a display device according to still another one of various embodiments of the present disclosure in order to explain the display device; 
         FIG.  9    illustrates views for explaining a process of manufacturing a window member of a display device according to various embodiments of the present disclosure; 
         FIG.  10    is a perspective view illustrating a window member of a display device according to various embodiments of the present disclosure; 
         FIG.  11    is a view for explaining compressive force or tensile force formed in a curved portion of a window member; 
         FIG.  12    is a view illustrating a curved portion of a window member of a display device according to various embodiments of the present disclosure; 
         FIG.  13    is a block diagram illustrating an electronic device according to various embodiments of the present disclosure; 
         FIG.  14    is a cross-sectional view schematically illustrating the configuration of an electronic device according to one of various embodiments of the present disclosure in a folded state; 
         FIG.  15    is a cross-sectional view schematically illustrating the configuration of an electronic device according to another one of various embodiments of the present disclosure in a folded state; and 
         FIGS.  16 ,  17 ,  18 ,  19 , and  20    are cross-sectional views illustrating partial configurations of display devices according to various embodiments of the present disclosure, respectively. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, various embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that there is no intent to limit the present disclosure to the particular forms disclosed herein; rather, the present disclosure should be construed to cover various modifications, equivalents, and/or alternatives of embodiments of the present disclosure. In describing the drawings, similar reference numerals may be used to designate similar constituent elements. 
     In the various embodiments of the present disclosure, the expression “A or B”, “at least one of A or/and B”, or “one or more of A or/and B” may include all possible combinations of the items listed. For example, the expression “A or B”, “at least one of A and B”, or “at least one of A or B” refers to all of (1) including at least one A, (2) including at least one B, or (3) including all of at least one A and at least one B. 
     The expression “a first”, “a second”, “the first”, or “the second” used in various embodiments of the present disclosure may modify various components regardless of the order and/or the importance but does not limit the corresponding components. For example, a first user device and a second user device indicate different user devices although both of them are user devices. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element without departing from the scope of the present disclosure. 
     It should be understood that when an element (e.g., first element) is referred to as being (operatively or communicatively) “connected,” or “coupled,” to another element (e.g., second element), it may be directly connected or coupled directly to the other element or any other element (e.g., third element) may be interposer between them. In contrast, it may be understood that when an element (e.g., first element) is referred to as being “directly connected,” or “directly coupled” to another element (second element), there are no element (e.g., third element) interposed between them. 
     The expression “configured to” used in the present disclosure may be exchanged with, for example, “suitable for”, “having the capacity to”, “designed to”, “adapted to”, “made to”, or “capable of” according to the situation. The term “configured to” may not necessarily imply “specifically designed to” in hardware. Alternatively, in some situations, the expression “device configured to” may mean that the device, together with other devices or components, “is able to”. For example, the phrase “processor adapted (or configured) to perform A, B, and C” may mean a dedicated processor (e.g., embedded processor) only for performing the corresponding operations or a generic-purpose processor (e.g., Central Processing Unit (CPU) or Application Processor (AP)) that can perform the corresponding operations by executing one or more software programs stored in a memory device. 
     In the present disclosure, the terms are used to describe specific embodiments, and are not intended to limit the present disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. In the description, it should be understood that the terms “include” or “have” indicate existence of a feature, a number, a step, an operation, a structural element, parts, or a combination thereof, and do not previously exclude the existences or probability of addition of one or more another features, numeral, steps, operations, structural elements, parts, or combinations thereof. 
     Unless defined differently, all terms used herein, which include technical terminologies or scientific terminologies, have the same meaning as that understood by a person skilled in the art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted to have the meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted to have ideal or excessively formal meanings unless clearly defined in the present specification. In some cases, terms defined in this specification may not be interpreted as excluding embodiments of the present disclosure. 
     In the present disclosure, an electronic device may be a random device, and the electronic device may be called a terminal, a portable terminal, a mobile terminal, a communication terminal, a portable communication terminal, a portable mobile terminal, a touch screen or the like. 
     For example, the electronic device may be a smartphone, a portable phone, a game player, a TV, a display unit, a heads-up display unit for a vehicle, a notebook computer, a laptop computer, a tablet Personal Computer (PC), a Personal Media Player (PMP), a Personal Digital Assistants (PDA), and the like. The electronic device may be implemented as a portable communication terminal which has a wireless communication function and a pocket size. Further, the electronic device may be a flexible device or a flexible display device. 
     The electronic device may communicate with an external electronic device, such as a server or the like, or perform an operation through an interworking with the external electronic device. For example, the electronic device may transmit an image photographed by a camera and/or position information detected by a sensor unit to the server through a network. The network may be a mobile or cellular communication network, a Local Area Network (LAN), a Wireless Local Area Network (WLAN), a Wide Area Network (WAN), an Internet, a Small Area Network (SAN) or the like, but is not limited thereto. 
       FIG.  1    is a perspective view illustrating an electronic device  10  that includes a display device  15  according to various embodiments of the present disclosure.  FIG.  2    is a cross-sectional view illustrating the electronic device  10  that includes the display device  15  according to various embodiments of the present disclosure. 
     Referring to  FIGS.  1  and  2   , an electronic device  10  including the display device  15  according to various embodiments of the present disclosure may be a folder-type electronic device that includes a pair of housings  11  and  13 , which are pivotably coupled to each other by a hinge device  17 . For example, the housings  11  and  13  may be folded or unfolded with respect to each other by rotating about a hinge axis H provided by the hinge device  17 . The display device  15  is a flexible display device, which is at least partially bendable. Of the housings  11  and  13 , a portion of the display device  15  is arranged in and mounted on a first housing  11 , and another portion of the display device  15  is arranged in and mounted on the second housing  13  of the housings  11  and  13 . The display device  15  may be integrated with a touch panel so as to be used as an input device. For example, a virtual keypad may be implemented in a region of the display device  15  so that the user may conveniently input desired information even if the electronic device  10  does not have a physical keypad. 
     In the state in which the first and second housings  11  and  13  are folded, the display device  15  is deformed into a curved shape having a predetermined curvature at a position adjacent to the hinge device  17  so as to be bent together with the first and second housings  11  and  13 . When the first and second housings  11  and  13  are rotated and unfolded with respect to each other, the display device  15  may also be unfolded in a flat plate shape so as to output a screen. Therefore, the user may easily carry the electronic device  10  by folding the first and second housings  11  and  13 , and when using the electronic device  10 , the first and second housings  11  and  13  may be extended, so that it is possible to confirm various pieces of information, (e.g., an image, a text, or a video image) output through the large screen. In addition, as described above, by implementing the virtual keypad through the display device  15  as required, the user may store or output desired information and the like through the electronic device  10 . 
     As mentioned above, the display device  15  may be at least partially deformed in a curved shape. For example, when the first and second housings  11  and  13  are folded to face each other, the display device  15  may be curved in a portion adjacent to the hinge device  17 . As will be described later, the display device  15  may include a window member, and the thickness of the window member may be formed smaller in a portion that is to be deformed in a curved shape than in the other portions. 
       FIG.  3    is a cross-sectional view illustrating the configuration of a conventional flexible display device in the state in which external pressure is applied thereto. 
     Referring to  FIG.  3   , a conventional flexible display device  15  may have a sufficiently thin thickness to be deformed in a curved shape. Therefore, the display element  15   a  and the window member  15   c  for protecting the display element  15   a  may have a sufficiently thin thickness. In a conventional flexible display device, the window member  15   c  may have a surface hardness that is resistant to damage, such as scratches, by including a cured coating layer. However, when external pressure is applied in the state in which the window member  15   c  is laminated and bonded to the display element  15   a  by an Optically Clear Adhesive (OCA)  15   b , the window member  15   c  may be deformed in a portion  15   d  to which pressure is applied. The deformation of the window member  15   c  transfers the externally applied pressure to the display element  15   a  and may thus cause distortion of the screen in the portion  15   e  where the pressure is applied on the display element  15   a , or damage to the display element  15   a.    
     The mechanical strength of the window member  15   c  can be improved by increasing the thickness of the window member  15   c  in order to prevent the distortion of the screen or damage to the display element. However, as described above, this may also decrease the flexibility of the flexible display device. 
     Therefore, according to various embodiments of the present disclosure, the display device may include a window member having a structure that is capable of securing flexibility while preventing the distortion of a screen or damage to the display element due to external pressure or the like. According to various embodiments of the present disclosure, the window member of the display device may be formed to be thinner in a portion (e.g., a portion where flexibility is required) than the other portions, thereby ensuring flexibility. In the display device according to various embodiments of the present disclosure, since the thickness of the window member can be sufficiently secured in the portion where flexibility is not required, it is possible to prevent external pressure from being transferred to the display element. 
       FIG.  4    is a cross-sectional view illustrating the configuration of a display device  15  according to one of various embodiments of the present disclosure.  FIG.  5    is a view illustrating a window member  153  of the display device  15  according to one of various embodiments of the present disclosure. 
     Referring to  FIGS.  4  and  5   , according to one of various embodiments of the present disclosure, the display device  15  includes a curved portion  159   a  formed in at least a portion of the window member  153 , thereby forming a thickness smaller than the other portions of the window member  153 , in which the curved portion  159   a  is not formed. As will be described below, the curved portion does not necessarily have to be formed in order to make the thickness of a portion of the window member  153  smaller than the other portions. For example, a stepped portion may be formed on one face or both faces of the window member  153  such that the thickness of a portion of the window member  153  may be thinner than the other portions. When the curved portions  159   a  (or the stepped portions) are formed on both faces of the window member  153 , the curved portions  159   a  (or the stepped portions) may be symmetrically arranged. 
     The window member  153  may be stacked on one face of the flexible display element  151  and may be bonded to the display element  151  by an optical adhesive  155 . The window member  153  and the optical adhesive  155  may each be made of a transparent material, and may transmit a screen output from the display element  151 . The flexibility of the window member  153  may be increased at the portion where the curved portion  159   a  is formed. When the display device  151  is mounted on an electronic device (e.g., the electronic device  10 ), a portion (e.g., a portion thinner than the other portions) of the window member  151  may be disposed in the vicinity of the hinge device  17  described above or in a region which is bent in a curved shape, so that the portion can be deformed in a curved shape in an operation of opening/closing the electronic device  10 . 
     The curved portion  159   a  may be formed on one face or on each face of the window member  153 . When the curved portion  159   a  is formed on one face of the window member  153  and the electronic device  10  is folded, the curved portion  159   a  may be formed on the face, which is convexly deformed as the window member  153  is deformed in a curved shape. In addition, as described above, the curved portion  159   a  may be formed on each face of the window member  153 . The position or the like of the curved portion  159   a  formed on the window member  153  may be variously set according to the specification of the electronic device, on which the display device  15  is to be mounted. The curved portion  159   a  may have a curved groove shape extending in the width direction W of the window member  153  and may have a shape in which the thickness of the window member  153  gradually increases while extending from the center portion toward the edges of the window member  153  in the longitudinal direction L of the window member  153 . 
     When the display device  15  includes a touch-screen function, the curved portion  159   a  may correspond to a portion that accepts an input operation (e.g., a physical touch) of the user. The width of the curved portion  159   a  (e.g., the size of the curved portion  159   a  in the longitudinal direction L of the window member  153 ) may be smaller than an area to be touched by the user&#39;s body. Therefore, even if the window member  153  is formed thin enough to be flexible in the portion in which the curved portion  159   a  is formed, it is possible to prevent the pressure applied to the curved portion due to the user&#39;s body contact or the like from being transferred to the display element  151 . 
     The window member  153  may be formed by processing a transparent synthetic resin film. In order to secure the surface hardness thereof, a cured coating layer may be formed on the outer face of the synthetic resin film for forming the window member  153 . The cured coating layer may be formed by coating or depositing a material, such as ceramic or acryl, on one face (e.g., the outer face) of the synthetic resin film. Processing a portion (e.g., the curved portion  159   a ) of the window member  153  to have a thin thickness may be performed simultaneously with forming the synthetic resin film. For example, a synthetic resin film may be manufactured using processes, such as roller pressing, film extrusion, stamping, and cell casting, and the shape of a roller, a mold, or the like may be stamped on the above-described curved portion  159   a  in advance, so that the portion of the synthetic resin film can be formed thinner than the other portions simultaneously with the formation of the synthetic resin film. According to various embodiments, the synthetic resin film for forming the window member  153  may be formed to have a predetermined thickness, and the manufactured synthetic resin film may be subjected to mechanical processes (e.g., polishing, lathe processing, laser processing, etc.) so as to form the curved surface portion  159   a  or the like. 
     Depending on the size of the display device  15  or the folded shape of the electronic device  10 , the width of the curved portion  159   a  may be formed to be larger than an area to be touched by the user&#39;s body. When the width of the curved portion  159   a  is formed to be large, it may be difficult to prevent the pressure applied to a portion corresponding to the curved portion  159   a  from being transferred to the display device  151  by the window member  153  itself. According to various embodiments, the display device  15  may further include a reinforcing layer  157 , thereby securing the mechanical strength of the portion in which the curved portion  159   a  is formed (i.e., the portion of the window member  153  that is thinner than the other portions). For example, the reinforcing layer  157  may prevent a portion of the window member  153  that corresponds to the curved surface portion  159   a , from being deformed due to a physical touch or the like. 
     According to various embodiments, the reinforcing layer  157  may compensate for deviation in image quality that may occur due to the variation in the thickness of the window member  153 . That is, since the thickness of the window member  153  is not uniform, a quality difference may occur in an image that has been transmitted through the window member  153  due to the difference in thickness. This image quality deviation may degrade the image quality of the screen output from the display element  151 . For example, there may be a difference between the screen brightness of the portion where the curved portion  159   a  is formed and the screen brightness of the other portions. The reinforcing layer  157  may be formed to maintain uniform optical properties of the window member  153  and uniform mechanical strength of the window member  153 . The compensation layer  157  may be formed of a material having a refractive index similar to or the same as the refractive index of the window member  153 . 
       FIG.  6    is a view illustrating various modifications of the window member of the display device according to one of various embodiments of the present disclosure. 
     According to various embodiments of the present disclosure, a shape for reducing the thickness of a portion of the window member  153  (e.g., the curved portion  159   a  described above) may be formed on one face or each face of the window member  153 , and may be replaced by various shapes of stepped portions  159   b . In the following detailed description, the reference numerals for the window members may be given differently depending on the shape of the curved portion  159   a  or the stepped portion  159   b , and the term “window member” denoted by reference numeral  153  may be used to mean window members each including curved portions  159   a  or stepped portions  159   b  having different shapes. 
     For example, the window members indicated by reference numerals  153   a  and  153   b  may include a rectangular stepped portion  159   b , the window members indicated by reference numerals  153   e  and  153   f  may include a central flat portion and a stepped portion  159   b  having inclined portions extending toward edges in the longitudinal direction of the members  153   e  and  153   f , and the window members indicated by the reference numerals  153   g  and  153   h  may include stepped portions  159   b  in a step shape, which gradually increase the thickness of the window members  153   g  and  153   h  as extending from the center toward the edges in the longitudinal direction of the window members  153   g  and  153   h . As described above, the structure for making the thickness of the window member  153  smaller than the other portions may be formed of a curved portion  159   a  or a stepped portion  159   b , and the shapes thereof may be variously processed. 
     The stepped portion  159   b  may have a groove shape extending in the width direction W of the window member  153  similarly to the curved portion  159   a . However, in the configuration of the present disclosure, the configuration (e.g., the stepped portion  159   b  or the curved portion  159   a ) for making the thickness of the window member  153  smaller than the other portions does not necessarily have to extend in the width direction W of the window member  153 . For example, when the display device  15  is mounted on the electronic device  10 , the direction, number, and positions of the stepped portions  159   b  or the curved portions  159   a  formed as described above may be appropriately set and arranged in consideration of the structure, direction, etc. in which the electronic device  10  is folded. 
       FIG.  7    is a cross-sectional view illustrating the configuration of a display device  15  according to another one of various embodiments of the present disclosure in order to explain the display device  15 .  FIG.  8    is a cross-sectional view illustrating the configuration of a display device  15  according to still another one of various embodiments of the present disclosure in order to explain the display device  15 . 
     Referring to  FIGS.  7  and  8   , the reinforcing layer  157  described above may be formed of a transparent material, such as silicon oxide (SiO x ), in the stepped portion  159   b  (or the curved surface portion  159   a ) on the window member, or on the entirety of one face (or each face) of the window member  153 , which is formed with the stepped portion  159   b  (or the curved surface portion  159   a ), so as to make the portion that is formed with the stepped portion  159   b , flush with the other portions on the one face (or each face) of the window member  153 . The window member  153  may be bonded to the display element  151  by an optical adhesive  155  in the state in which the reinforcing layer  157  is formed. Therefore, the reinforcing layer  157  may be sealed between the window member  153  and the optical adhesive  155 . The reinforcing layer  157  may reinforce the mechanical strength of the window member  153 , as described above. For example, in the state in which the display device  151  is unfolded, by reinforcing the strength of a portion of the window member  153  (e.g., the portion in which the stepped portion  159   b  or the curved portion  159   a  is formed) having a smaller thickness in comparison with the other portions, it is possible to prevent external pressure applied due to the user&#39;s physical touch or the like from being transferred to the display device  151 . In addition, the deviation in image quality, which may occur due to the non-uniform thickness of the window member  153 , can be compensated for by forming the reinforcing layer  157 . 
     The window member  153  of the display device described above includes the curved portion  159   a  (or the stepped portion) so that the window member can be easily processed in a curved shape. For example, although the window member  153  need not be flexible, the curved portion can be easily formed by forming the curved portion  159   a  (or the stepped portion) in the window member  153  if the window member  153  has a partially curved surface. 
       FIG.  9    illustrates views for explaining a process of manufacturing a window member  153  of the display device (S 10 ) according to various embodiments of the present disclosure. 
     The window member  153  may be a piece of tempered glass having a flat shape and a uniform thickness before being processed into a curved portion. A curved portion  159   a  (or a stepped portion) may be formed in a certain portion of the tempered glass material in the form of a flat plate (S 11 ). The curved portion  159   a  (or the stepped portion) may be formed by pressing the tempered glass material by a roller having a projection on the outer surface thereof, or through processes, such as etching, polishing, lathe processing, laser processing, and the like. According to various embodiments, the curved portion may be formed simultaneously with the formation of a piece of flat tempered glass through a cell-casting process. 
     The window member  153 , which is formed with the curved surface portion  159   a  on one face or each face thereof, may be processed into a partially curved shape from the flat shape by being bent at least partially through the thermoforming (S 13 ). In the process of thermoforming (S 13 ), the flat window member  153  may be pressed by the press  230  in the state of being mounted on the base  210 , thereby being deformed to conform to the curved shape formed on the base  210 . While being pressed by the press  230 , heat may be applied to the flat window member  153  so as to facilitate deformation to the curved surface shape. 
     The curved portion  159   a  is provided so as to form the thickness T 1  of the portion of the window member  153  to be smaller than the thickness T 2  of the other portions, and when the window member  153  is processed from the flat shape into the shape having the curved shape, the portion in which the curved portion  159   a  is formed can be deformed. The state in which the window member  153  is processed into the curved shape is illustrated in “S 15 ”. 
       FIG.  10    is a perspective view illustrating a window member  153  of a display device according to various embodiments of the present disclosure.  FIG.  11    is a view for explaining compressive force or tensile force formed in a curved portion of a window member.  FIG.  12    is a view illustrating a curved portion of a window member  153  of a display device according to various embodiments of the present disclosure. 
     Referring to  FIGS.  10  and  11   , in partially processing the window member  153  from a flat shape to a curved shape, locally different forces may be applied to the inner surface and the outer surface of the curved surface portion, respectively. For example, when there is no change in length even after being deformed into a curved shape along the center line of the window member (neutral axis), compressive force may be applied to the inner side of the center line (neutral axis), and tensile force may be applied on the outer side thereof. When there is no change in the length of the inner face of the window member after being deformed into a curved shape, tensile force may act on the outer face. When there is no change in the length of the outer face of the window member after being deformed into a curved shape, compressive force may act on the inner face. In this way, when the flat window member is deformed into a curved shape, deviation may occur between the force acting on the inner face and the force acting on the outer face of the deformed portion, which may lead to a molding failure of the window member. Further, as the flat window member becomes thicker, the deviation between the forces generated in the portion deformed into the curved shape may become larger. In order to prevent this, it is possible to process a flat tempered glass material into a curved window member while heating for a sufficient time in the thermoforming process. 
     Referring to  FIG.  12   , the window member  153  of the display device according to various embodiments of the present disclosure may be first formed with the curved portion  159   a  at a portion to be deformed into a curved shape before it is processed into the curved shape. For example, the portion to be deformed into the curved surface may be processed such that the thickness T 1  thereof is made to be smaller than the thickness T 2  of the other portions. As described above, in processing the flat window member  153  into a curved shape, when the thickness of the window member  153  is thick, a deviation may increase between forces generated in the deformed portion. The window member  153  of the display device according to various embodiments of the present disclosure may alleviate the defective formation of the window member  153  by reducing the deviation between the forces generated by processing the thickness of the portion deformed into the curved shape to be smaller than other portions. In addition, it is possible to reduce the time required for the thermoforming process by reducing the defects caused by the deviation between the forces. 
       FIG.  13    is a block diagram illustrating an electronic device  20  according to various embodiments of the present disclosure. 
     Referring to  FIG.  13   , the electronic device  20  may include, for example, all or part of the electronic device  10  illustrated in, for example,  FIG.  1   . The electronic device  20  may include at least one processor (e.g., Application Processor (AP))  21 , a communication module  22 , a subscriber identification module  22   g , a memory  23 , a sensor module  24 , an input device  25 , a display  26 , an interface  27 , an audio module  28 , a camera module  29   a , a power management module  29   d , a battery  29   e , an indicator  29   b , and a motor  29   c.    
     The processor  21  may drive, for example, an operating system or an application so as to control a plurality of hardware or software components connected thereto, and may also perform various data processing and arithmetic operations. The processor  21  may be implemented by, for example, a System-on-Chip (SoC). According to one embodiment, the processor  21  may further include a Graphic Processing Unit (GPU) and/or an image signal processor. The processor  21  may include at least some components (e.g., the cellular module  22   a ) among the components illustrated in  FIG.  13   . The processor  21  may load a command or data received from at least one of the other components (e.g., a non-volatile memory) in a volatile memory to process the command and data, and may store various data in non-volatile memory. 
     The communication module  22  may include, for example, a cellular module  22   a , a Wi-Fi module  22   b , a Bluetooth module  22   c , a GNSS module  22   d  (e.g., a GPS module, a GLONASS module, a BeiDou module, or a Galileo module), an NFC module  22   e , and a Radio Frequency (RF) module  22   f.    
     The cellular module  22   a  may provide, for example, a voice call, a video call, a message service, or an internet service through, for example, a communication network. According to one embodiment, the cellular module  22   a  may perform discrimination and authentication of the electronic device  20  within the communication network using the subscriber identification module (e.g., a SIM card)  22   g . According to one embodiment, the cellular module  22   a  may perform at least some of the functions that may be provided by the processor  21 . According to one embodiment, the cellular module  22   a  may include a Communication Processor (CP). 
     Each of the Wi-Fi module  22   b , the Bluetooth module  22   c , the GNSS module  22   d , and the NFC module  22   e  may include, for example, a processor to process data transmitted/received through a corresponding module. According to a certain embodiment, at least some (e.g., two or more) of the cellular module  22   a , the Wi-Fi module  22   b , the Bluetooth module  22   c , the GNSS module  22   d , and the NFC module  22   e  may be incorporated in a single Integrated Chip (IC) or an IC package. 
     The RF module  22   f  may transmit/receive, for example, a communication signal (e.g., an RF signal). The RF module  22   f  may include, for example, a transceiver, a Power Amp Module (PAM), a frequency filter, a Low Noise Amplifier (LNA), or an antenna. According to another embodiment, at least one of the cellular module  22   a , the Wi-Fi module  22   b , the Bluetooth module  22   c , the GNSS module  22   d , and the NFC module  22   e  may transmit/receive an RF signal through one or more separate RF modules. 
     The subscriber identification module  22   g  may include, for example, a card that includes a subscriber identification module and/or an embedded SIM, and may also include intrinsic identification information (e.g., an Integrated Circuit Card IDentifier (ICCID)) or subscriber information (e.g., an International Mobile Subscriber Identity (IMSI)). 
     The memory  23  may include, for example, an internal memory  23   a  or an external memory  23   b . The internal memory  23   a  may include at least one of, for example, volatile memory (e.g., a Dynamic RAM (DRAM), a Static RAM (SRAM), or a Synchronous DRAM (SDRAM)), and non-volatile memory (e.g., a One-Time Programmable ROM (OTPROM), a Programmable ROM (PROM), an Erasable and Programmable ROM (EPROM), an Electrically Erasable and Programmable ROM (EEPROM), a mask ROM, a flash ROM, a flash memory (e.g., a NAND flash memory or a NOR flash memory), a hard drive, or a Solid-State Drive (SSD)). 
     The external memory  23   b  may further include a flash drive (e.g., Compact Flash (CF), Secure Digital (SD), Micro Secure Digital (Micro-SD), Mini Secure Digital (Mini-SD), extreme Digital (xD), Multi-Media Card (MMC), or memory stick). The external memory  23   b  may be functionally and/or physically connected to the electronic device  20  through any of various interfaces. 
     For example, the sensor module  24  may measure a physical quantity or may sense the operating status of the electronic device  20 , and may then convert the measured or sensed information into electric signals. The sensor module  24  may include at least one of, for example, a gesture sensor  24   a , a gyro sensor  24   b , an atmospheric pressure sensor  24   c , a magnetic sensor  24   d , an acceleration sensor  24   e , a grip sensor  24   f , a proximity sensor  24   g , a color sensor  24   h  (e.g., an RGB (Red, Green, Blue) sensor), a biometric sensor  24   i , a temperature/humidity sensor  24   j , an illuminance sensor  24   k , and an Ultra-Violet (UV) sensor  24   l . Additionally, or alternatively, the sensor module  24  may include, for example, an E-nose sensor, an ElectroMyoGraphy (EMG) sensor (not illustrated), an ElectroEncephaloGram (EEG) sensor, an ElectroCardioGram (ECG) sensor, an Infra-Red (IR) sensor, an iris sensor, and/or a fingerprint sensor. The sensor module  24  may further include a control circuit for controlling one or more sensors incorporated therein. In a certain embodiment, the electronic device  20  may further include a processor configured to control the sensor module  24  as a part of the processor  21  or separately from the processor  21  so as to control the sensor module  24  while the processor  21  is in the sleep state. 
     The input device  25  may include, for example, a touch panel  25   a , a (digital) pen sensor  25   b , a key  25   c , or an ultrasonic input device  25   d . As the touch panel  25   a , at least one of, for example, a capacitive-type touch panel, a resistive-type touch panel, an infrared-type touch panel, and an ultrasonic-type panel may be used. In addition, the touch panel  25   a  may further include a control circuit. The touch panel  25   a  may further include a tactile layer so as to provide a tactile reaction to a user. 
     The (digital) pen sensor  25   b  may be, for example, a portion of the touch panel or may include a separate recognition sheet. The key  25   c  may include, for example, a physical button, an optical key, or a keypad. The ultrasonic input device  25   d  may sense, through a microphone (e.g., a microphone  28   d ), ultrasonic waves that are generated by an input tool so as to confirm data corresponding to the sensed ultrasonic waves. 
     The display  26  may include a panel  26   a , a hologram device  26   b , or a projector  26   c . The panel  26   a  may include a configuration that is the same as or similar to that of the above-described display device  15 . The panel  26   a  may be implemented to be flexible, transparent, or wearable. The panel  26   a  may be configured as a single module with the touch panel  25   a . The hologram device  26   b  may show a stereoscopic image in the air using interference of light. The projector  26   c  may project light onto a screen so as to display an image. The screen may be located, for example, inside or outside the electronic device  20 . According to one embodiment, the display  26  may further include a control circuit to control the panel  26   a , the hologram device  26   b , or the projector  26   c.    
     The interface  27  may include, for example, a High-Definition Multimedia Interface (HDMI)  27   a , a Universal Serial Bus (USB)  27   b , an optical interface  27   c , or a D-subminiature (D-sub) interface  27   d . Additionally, or alternatively, the interface  27  may include, for example, a Mobile High-definition Link (MHL) interface, a Secure Digital (SD) card/Multi-Media Card (MMC) interface, or an Infrared Data Association (IrDA) standard interface. 
     The audio module  28  may bi-directionally convert sound and an electric signal. The audio module  28  may process sound information input or output through a speaker  28   a , a receiver  28   b , an earphone  28   c , a microphone  28   d , or the like. 
     The camera module  29   a  is a device that is capable of photographing, for example, a still image and a moving image. According to one embodiment, the camera module  29   a  may include one or more image sensors (e.g., a front sensor or a rear sensor), a lens, an Image Signal Processor (ISP), or a flash (e.g., LED or xenon lamp). 
     The power management module  29   d  may manage, for example, the electric power of the electronic device  20 . According to one embodiment, the power management module  29   d  may include a Power Management Integrated Circuit (PMIC), a charger Integrated Circuit (IC), or a battery or fuel gauge. The PMIC may be configured as a wired and/or wireless charging type. The wireless charging type may include, for example, a magnetic resonance type, a magnetic induction type, or an electromagnetic wave type, and may further include an additional circuit for wireless charging (e.g., a coil loop, a resonance circuit, or a rectifier). The battery gauge may measure the remaining charge of the battery  29   e , and a voltage, a current, or a temperature during charging. The battery  29   e  may include, for example, a rechargeable battery and/or a solar battery. 
     The indicator  29   b  may indicate a specific status of the electronic device  20  or of a part thereof (e.g., the processor  21 ), such as a booting status, a message status, or a charged status. The motor  29   c  may convert an electric signal into a mechanical vibration, and may generate, for example, a vibration or a haptic effect. Although not illustrated, the electronic device  20  may include a processor (e.g., a GPU) to support a mobile TV. The processor to support a mobile TV may process media data according to standards of, for example, Digital Multimedia Broadcasting (DMB), Digital Video Broadcasting (DVB), or MediaFlo™. 
     Each of the above-described component elements of hardware according to the present disclosure may be configured with one or more components, and the names of the corresponding component elements may vary based on the type of electronic device. The electronic device according to various embodiments of the present disclosure may include at least one of the aforementioned elements. Some elements may be omitted or other additional elements may be further included in the electronic device. Also, some of the hardware components according to various embodiments may be combined into one entity, which may perform functions identical to those of the relevant components before the combination. 
     The term “module” as used herein may, for example, mean a unit including one of hardware, software, and firmware or a combination of two or more of them. The “module” may be interchangeably used with, for example, the term “unit”, “logic”, “logical block”, “component”, or “circuit”. The “module” may be a minimum unit of an integrated component element or a part thereof. The “module” may be a minimum unit for performing one or more functions or a part thereof. The “module” may be mechanically or electronically implemented. For example, the “module” according to the present disclosure may include at least one of an Application-Specific Integrated Circuit (ASIC) chip, a Field-Programmable Gate Arrays (FPGA), and a programmable-logic device for performing operations which has been known or are to be developed hereinafter. 
     According to various embodiments, at least some of the devices (for example, modules or functions thereof) or the method (for example, operations) according to the present disclosure may be implemented by a command stored in a computer-readable storage medium in a programming module form. When the command is executed by one or more processors, the one or more processors may perform a function corresponding to the command. 
     The computer readable recoding medium may include a hard disk, a floppy disk, magnetic media (e.g., a magnetic tape), optical media (e.g., a Compact Disc Read Only Memory (CD-ROM) and a Digital Versatile Disc (DVD)), magneto-optical media (e.g., a floptical disk), a hardware device (e.g., a Read Only Memory (ROM), a Random Access Memory (RAM), a flash memory), and the like. In addition, the program instructions may include high class language codes, which can be executed in a computer by using an interpreter, as well as machine codes made by a compiler. The aforementioned hardware device may be configured to operate as one or more software modules in order to perform the operation of the present disclosure, and vice versa. 
       FIG.  14    is a cross-sectional view schematically illustrating the configuration of an electronic device  1400  according to one of various embodiments of the present disclosure in a folded state.  FIG.  15    is a cross-sectional view schematically illustrating the configuration of an electronic device  1500  according to another one of various embodiments of the present disclosure in a folded state. 
     According to various embodiments of the present disclosure, the electronic device  1400  or  1500  may be folded such that the display device (e.g., the display element  1402 ) can be exposed to the outside, as illustrated in  FIG.  14   . Likewise, the electronic device  1400  or  1500  may be folded such that the display device (e.g., display element  1502 ) can be concealed, as illustrated in  FIG.  15   . For example, according to an embodiment, the window member  1403  or  1503  may be located on the outer or inner face of the electronic device  1400  or  1500  in the state in which the electronic device  1400  or  1500  is folded. For example, as illustrated in  FIG.  14   , when the electronic device  1400  is folded, the window member  1403  is positioned on the outer face of the electronic device  1400  such that the screen output region of the display device  1402  can be exposed. In another embodiment, as illustrated in  FIG.  15   , when the electronic device  1500  is folded, the window member  1503  may be positioned on the inner face of the electronic device  1500  such that the display element  1502  can be concealed. 
     The display element  1402  or  1502  of the electronic device  1400  or  1500  can be protected by the cover panel  1401  or  1501  and the window member  1403  or  1503 . For example, the cover panel  1401  or  1501  may be disposed to cover the display element  1402  or  1502  on one face of the display element  1402  or  1502 , and the window member  1403  or  1503  may be coupled to face the other face of the display device  1402  or  1502 . 
     According to various embodiments of the present disclosure, the above-mentioned curved portion or stepped portion does not necessarily have to be formed as long as the window member is flexibly deformed corresponding to the folding operation of the electronic device and the flat shape (or state) or the curved shape (or state) can be stably maintained even if external pressure (e.g., the user&#39;s touch input) is applied. For example, according to various embodiments of the present disclosure, the window member may be fabricated in a flat shape or a film shape having a substantially uniform thickness. For example, as will be described with reference to  FIGS.  16  to  20   , the first film member may be laminated on the window member, making the window member thinner so as to stably maintain the flat shape or the curved shape thereof while securing flexibility. 
       FIGS.  16  to  20    are cross-sectional views illustrating partial configurations of display devices according to various embodiments of the present disclosure, respectively. 
     Referring to  FIG.  16   , according to various embodiments of the present disclosure, a display device  1605  (e.g., the display device  15  of  FIG.  4   ) may further include a first film member  1655  laminated on a window member  1653 . The window member  1653  may include, for example, a thin glass, and may have a flat shape or a film shape with a substantially uniform thickness in the entire region thereof. According to one embodiment, the window member  1653  may be made entirely or partly of tempered glass by a chemical strengthening treatment. 
     According to various embodiments, the first film member  1655  may be laminated on at least one face of the window member  1653 . For example, the first film member  1655  may be laminated on the outer face of the window member  1653 , which is exposed to the outside, thereby protecting the window member  1653  from the external environment. According to various embodiments, the first film member  1655  may include a polyimide film or a thermoplastic polyurethane film, and in some embodiments, the first film member  1655  may include a hard coating component or an anti-fingerprint coating component. For example, the first film member  1655  may protect the window member  1653  from damage, such as scratches, or contamination, such as stains or foreign matter adhered thereto. 
     Referring to  FIG.  17   , according to various embodiments of the present disclosure, a display device  1705  may further include a first film member  1755  laminated to a window member  1753  and a second film member  1757  bonded to the surface of the first film member  1755 . The second film member  1757  may protect the window member  1753  together with the first film member  1755 , and may be formed of a polyimide film or a thermoplastic polyurethane film. In some embodiments, the second film member  1757  may prevent the window member  1753  and/or the first film member  1755  from being damaged or contaminated. 
     Referring to  FIG.  18   , according to various embodiments of the present disclosure, a display device  1805  may include first film members  1855 , which are respectively laminated on both faces of a window member  1853 . For example, according to various embodiments of the present disclosure, the first film member  1855  described above may be laminated on any one face of the window member  1853 , or may be laminated on each face of the window member  1853 . Although not illustrated, the second film member (e.g., the second film member  1757  of  FIG.  17   ) described above may be further attached to the surface of any one of the first film members  1855 . 
     Referring to  FIG.  19   , according to various embodiments of the present disclosure, a display device  1905  may include a reinforcing layer  1959  forming a layer, which is the same as a window member  1953 . The reinforcing layer  1959  may be disposed such that an area of the window member  1953 , which is deformed in a curved shape, may be partially replaced with the reinforcing layer  1959  when the above-described electronic device (e.g., the electronic device  1400  or  1500  illustrated in  FIG.  14    or  FIG.  15   ) is folded. The reinforcing layer  1959  may improve the flexibility in, for example, a region of the layer in which the window member  1953  is disposed. In some embodiments, the reinforcing layer  1959  is able to compensate for a difference in image quality between a portion of the region, in which the window member  1953  is not disposed and a region in which the window member  1953  is disposed. The display device  1905  may further include a first film member  1955  laminated on one face of the window member  1953  and/or one face of the reinforcing layer  1959 . The first film member  1955  is able to prevent the window member  1953  and/or the reinforcing layer  1959  from being damaged or contaminated. Although not illustrated, the above-described second film member (e.g., the second film member  1757  of  FIG.  17   ) may be further attached to the surface of the first film member  1955 . 
     Referring to  FIG.  20   , according to various embodiments of the present disclosure, a display device  2005  may include a curved portion and/or a stepped portion (e.g., the curved portion  159   a  of  FIG.  4   ) formed on one face (or each face) of a window member  2053 , and a curved portion, which is formed on one face of the window member  2053 , may be filled with a transparent synthetic resin, an optical adhesive, or the like, thereby forming a reinforcing layer  2059 . According to various embodiments, the display device  2005  may further include a first film member  2055 , which is laminated on one face of the window member  2053 , which is formed with the reinforcing layer  2059 , and/or the other face of the window member  2053 . The first film member  2055  is able to prevent the window member  2053  and/or the reinforcing layer  2059  from being damaged or contaminated. Although not illustrated, the above-described second film member (e.g., the second film member  1757  of  FIG.  17   ) may be further attached to the surface of the first film member  2055 . 
     As described above, according to various embodiments of the present disclosure, a display device may include: a display element, at least a portion of which is deformable in a curved shape; and a flexible window member stacked on the display element. A portion of the window member may be formed to have a thickness smaller than the thickness of a remaining portion of the window member. 
     According to various embodiments, the display device may further include a reinforcing layer stacked on one face of the window member. The reinforcing layer may compensate for a variation in the quality of an image transmitted through the window member, the variation being caused by the difference in the thickness of the window member. 
     According to various embodiments, in at least one face of the window member, a portion of the window member may include a stepped portion or a curved portion such that the portion of the window member has a thickness smaller than the thickness of a remaining portion of the window member. 
     According to various embodiments, the stepped portion may have a groove shape that extends in the width direction of the window member. 
     According to various embodiments, the stepped portion may have a step shape, which gradually increases the thickness of the window member from a center thereof toward an edge thereof in the longitudinal direction of the window member. 
     According to various embodiments, the stepped portion may include a central flat portion and an inclined portion extending toward the edge in the longitudinal direction of the window member. 
     According to various embodiments, the stepped portion may have a groove shape, which extends in the width direction of the window member and gradually increases the thickness of the window member from the center toward the edge in the longitudinal direction of the window member. 
     According to various embodiments, the stepped portion or the curved portion may be formed on each face of the window member. 
     According to various embodiments, the stepped portion or the curved portion may be formed on a face, which becomes convex when the window member is deformed in a curved shape. 
     According to various embodiments, the above-described display device may further include a reinforcing layer formed in at least the stepped portion or the curved portion on the window member. The reinforcing layer may compensate for a variation in the quality of image transmitted through the window member, the variation being caused by a difference in the thickness of the window member. 
     According to various embodiments, the reinforcing layer may be formed in an entirety of at least one face of the window member, in which the stepped portion or the curved portion is formed. 
     According to various embodiments of the present disclosure, a display device may include: 
     a display element, at least a portion of which is deformable in a curved shape; 
     a flexible window member stacked on the display element; and 
     a first film member laminated on at least one face of the window member. 
     According to various embodiments, the first film member may include a polyimide film or a thermoplastic polyurethane film. 
     According to various embodiments, the first film member may contain a cured coating component or an anti-fingerprint coating component. 
     According to various embodiments, the display device may further include a second film member bonded to a surface of the first member. 
     According to various embodiments, a portion of the window member may be formed to have a thickness smaller than the thickness of a remaining portion of the window member. 
     An electronic device according to various embodiments of the present disclosure may include the display device described above. 
     According to various embodiments, the electronic device may further include: a first housing; a second housing that pivots in a direction of being folded or unfolded with respect to the first housing; and a hinge device, which pivotably couples the second housing to the first housing. A portion of the display device may be mounted on the first housing and a remaining portion of the display device may be mounted on the second housing so as to be folded or unfolded with respect to the second housing. 
     According to various embodiments, the display device may be formed such that a portion of the display device adjacent to the hinge device has a thickness smaller than the thickness of a remaining portion of the display device. 
     According to various embodiments, the display device may be deformed into a curved shape in a portion adjacent to the hinge device when the second housing is folded to the first housing. 
     While the present disclosure has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims.