Patent Publication Number: US-2022217863-A1

Title: Electronic device with structure to reduce damage to glass

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of International Application No. PCT/KR2022/000176, filed on Jan. 5, 2022, which claims priority to Korean Patent Application No. 10-2021-0001103, filed on Jan. 5, 2021 in the Korean Intellectual Property Office, the disclosures of which are herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Certain embodiments of the disclosure relate to a foldable electronic device capable of reducing damage to glass. 
     BACKGROUND ART 
     Electronic devices are becoming slimmer, while maintaining or improving rigidity and strengthen. Moreover, electronic devices are being transformed from a uniform rectangular shape into a variety of shapes. For example, electronic devices may have a deformable structure or foldable structure. The foldable structure allows the user to have the benefit of both portability and a large screen. When the electronic device is being ported, the user can bend or fold the electronic device, thus reducing the dimensions of the electronic device. This makes easier to carry in a pocket or purse. However, when the user is using the electronic device, the user can unfold the electronic device thereby enjoying the increased screen size. 
     As part of the deformable structure, the electronic devices include a foldable electronic device including a flexible display that operates in such a manner that at least two housings are folded or unfolded with respect to each other, and various improvement measures according to the application of the flexible display are being prepared. 
     A foldable electronic device may include a hinge. The hinge movably couples the first and second housings to each other hinge. This foldable electronic device can operate in an in-folding and/or out-folding manner by the operation in which the first housing rotates in a range of 0 to 360 degrees with respect to the second housing through the hinge. The foldable electronic device may include a flexible display disposed to cross the first housing and the second housing when the foldable electronic device is in an open state of 180 degrees. 
     A glass layer of the flexible display may include UTG (ultra-thin glass) so that the glass layer is bendable. Compared to a transparent polyimide (PI) film, UTG has excellent visibility (transparency) and hardness (hardness of a surface), but may be easily broken or cracked by an external impact. 
     Meanwhile, in the foldable electronic device, a bent surface of a folded portion in the flexible display, which is located at the boundary between the first housing and the second housing, may be visible to the naked eye. The visibility of the folded portion aesthetically unpleasing. 
     SUMMARY 
     According to certain embodiments of the disclosure, it is possible to provide an electronic device that protects glass from an external impact and avoid the visible bent surface of a folded portion in the flexible display. 
     According to certain embodiments, an electronic device comprises a first housing; a second housing; a hinge disposed between the first housing and the second housing such that the second housing is foldable at one end of the first housing; and a flexible display disposed on a surface of the first housing and a surface of the second housing, wherein the flexible display comprises a display panel, and a glass layer disposed on the display panel, such that the display panel is between the glass layer and the surface of the first housing and the surface of the second housing, wherein the glass layer comprises: a bendable portion configured to be flat in an unfolded state when the first housing and the second housing are disposed horizontally adjacent, and to be bent in a folded state when the first housing and the second housing are vertically adjacent; and a first flat portion adjacent to the bending portion to form a boundary and a second flat portion disposed to extend from the first flat portion to an edge of the glass layer, wherein the glass layer comprises a glass member, wherein the glass member has a first thickness in the second flat portion, has a second thickness at the center of the bending portion, and has a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion and the center of the bending portion, and wherein the thickness of the glass member gradually decreases from the first flat portion to the center of the bending portion forming a concave portion. 
     According to another embodiment, a glass layer for a flexible display of a foldable electronic device, the glass comprises: a bending portion configured to be bent in a folded state of the foldable electronic device; and a first flat portion adjacent to the bending portion to form a boundary and a second flat portion disposed to extend from the first flat portion to an edge of the glass layer, a glass member, wherein the glass member has a first thickness in the second flat portion, has a second thickness at the center of the bending portion, and has a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion and the center of the bending portion, and wherein the thickness of the glass member gradually decreases from the first flat portion to the center of the bending portion to form a concave portion. 
     The electronic device according to certain embodiments of the disclosure can protect glass from an external impact, and can prevent an observable bent surface of the flexible display at the boundary between the first housing and the second housing. 
     In addition to this, various effects that are directly or indirectly recognized through the disclosure may be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating an unfolded state (unfolded stage) of an electronic device according to certain embodiments of the disclosure. 
         FIG. 2  is a diagram illustrating a folded state of the electronic device in  FIG. 1  according to certain embodiments of the disclosure. 
         FIG. 3  is an exploded perspective view of an electronic device according to certain embodiments of the disclosure. 
         FIG. 4A  is an exploded perspective view of an electronic device including a flexible display according to certain embodiments of the disclosure. 
         FIG. 4B  is a diagram illustrating configuration for each area of an electronic device according to certain embodiments of the disclosure. 
         FIG. 5  is a perspective view illustrating a stacked structure of a flexible display according to certain embodiments of the disclosure. 
         FIG. 6  is a cross-sectional view schematically illustrating a glass layer when an electronic device is in a folded state according to an embodiment. 
         FIG. 7  is a cross-sectional view schematically illustrating a glass layer when an electronic device is in an unfolded state according to an embodiment. 
         FIG. 8  is a cross-sectional view schematically illustrating a glass layer according to another embodiment. 
         FIG. 9  is a cross-sectional view illustrating irregularities formed on a glass layer according to an embodiment. 
         FIG. 10  is a cross-sectional view schematically illustrating a glass layer according to another embodiment. 
         FIG. 11  is a cross-sectional view schematically illustrating a glass layer according to another embodiment. 
         FIG. 12  is a cross-sectional view schematically illustrating a glass layer according to another embodiment. 
         FIG. 13  is a cross-sectional view illustrating irregularities formed on a glass layer according to another embodiment. 
         FIG. 14  is a cross-sectional view schematically illustrating an edge of a flexible display according to a comparative example. 
         FIG. 15  is a cross-sectional view schematically illustrating an edge of a flexible display according to an embodiment. 
         FIG. 16  is a cross-sectional view schematically illustrating an edge of a flexible display according to another embodiment. 
         FIG. 17  is a cross-sectional view schematically illustrating an edge of a flexible display according to another embodiment. 
         FIG. 18  is a cross-sectional view schematically illustrating an edge of a flexible display according to another embodiment. 
         FIG. 19  is a cross-sectional view schematically illustrating an edge of a flexible display according to another embodiment. 
         FIG. 20  illustrates a method of peeling a glass layer from the flexible display shown in  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show the unfolded ( FIG. 1 ) and folded state ( FIG. 2 ) of an foldable electronic device  100 . The foldable electronic device may include a hinge  164 . The hinge movably couples a first and second housing  110 ,  120  to each other. The foldable electronic device may include a flexible display  130  disposed to cross the first housing and the second housing when the foldable electronic device is in an open state of 180 degrees. 
     A glass layer is disposed on the flexible display. The glass layer can include UTG (ultra-thin glass) so that the glass layer is bendable with the first and second housings  110 ,  120 . 
     The electronic device according to certain embodiments of the disclosure can protect glass from an external impact, and can prevent an observable bent surface of the flexible display  130  at the boundary between the first housing  110  and the second housing  120 . 
       FIG. 1  is a diagram illustrating an unfolded state (unfolded stage) of an electronic device  100  according to certain embodiments of the disclosure. In the unfolded state, the housings  110  and  120  are horizontally adjacent.  FIG. 2  is a diagram illustrating a folded state of the electronic device  100  in  FIG. 1  according to certain embodiments of the disclosure. In the folded state, the housings  110  and  120  are vertically adjacent. 
     Referring to  FIGS. 1 and 2 , the electronic device  100  may include a pair of housings  110  and  120  (e.g., a foldable housing). The pair of housings  110  and  120  are rotatably coupled based on a folding axis A 1  by a hinge (e.g., the hinge  164  in  FIG. 3 ). The housings  110  and  120  can be folded against each other. A first display  130  (e.g., a flexible display, a foldable display, or a main display) is disposed on the surface of the pair of housings  110  and  120 , and a second display  151  (e.g., a sub-display). 
     The hinge (e.g., the hinge  164  in  FIG. 3 ) may be disposed so as not to be visible when the electronic device is in a folded state. Hinge cover  165  that protects the hinge and covers the foldable area in the unfolded state. In the disclosure, the surface on which the first display  130  is disposed may be defined as a front surface of the electronic device  100 , and the opposite surface of the front surface may be defined as a rear surface of the electronic device  100 . In addition, the surface surrounding the space between the front surface and the rear surface may be defined as a side surface of the electronic device  100 . 
     The housings  110  and  120  may include a first housing  110  and a second housing  120  that are foldable against each other through the hinge (e.g., the hinge  164  in  FIG. 3 ). The pair of housings  110  and  120  are not limited to the form and coupling shown in  FIGS. 1 and 2 , and may be implemented by a combination and/or coupling of other shapes or components. The first housing  110  and the second housing  120  may be disposed on both sides of the folding axis A 1 , and may have an overall symmetrical shape with respect to the folding axis A 1 . According to some embodiments, the first housing  110  and the second housing  120  may be folded asymmetrically with respect to the folding axis A 1 . The angle or distance between the first housing  110  and the second housing  120  may vary depending on whether the electronic device  100  is in an unfolded stage, a folded state, or an intermediate state. 
     The first housing  110  may include a first surface  111  that is connected to the hinge (e.g., the hinge  164  in  FIG. 3 ). The first surface  111  may be disposed to face the front surface of the electronic device  100  in the unfolded state of the electronic device  100 . The first housing may include a second surface  112  facing the opposite direction of the first surface  111 , and a first side member  113 . The first side member  113  may surround at least a portion of a first space between the first surface  111  and the second surface  112 . 
     The second housing  120  may include a third surface  121  that is connected to the hinge (e.g., the hinge  164  in  FIG. 3 ). The third surface  121  can be disposed to face the front surface of the electronic device  100  in the unfolded state of the electronic device  100 . The second housing  120  can also include a fourth surface  122  facing the opposite direction of the third surface  121 , and a second side member  123 . The side member can surround at least a portion of a second space between the third surface  121  and the fourth surface  122 . 
     The first surface  111  may be directed in the same direction as the third surface  121  in the unfolded state, and face the third surface  121  in the folded state. The electronic device  100  may include a recess  101  that is formed to accommodate the first display  130  through the structural coupling of the first housing  110  and the second housing  120 . The recess  101  may have substantially the same size as the first display  130 . 
     The hinge cover  165  may be disposed between the first housing  110  and the second housing  120 , thereby being disposed to be able to cover the hinge (e.g., the hinge  164  in  FIG. 3 ). The hinge cover  165  may be covered by a portion of the first housing  110  and the second housing  120  or exposed depending on the state of the electronic device  100 . For example, when the electronic device  100  is in the unfolded state, the hinge cover  165  may be covered by the first housing  110  and the second housing  120  so as not to be exposed. When the electronic device  100  is in the folded state, the hinge cover  165  may be exposed. In the case of the intermediate state in which the first housing  110  and the second housing  120  are folded with a certain angle, the hinge cover  165  may be at least partially exposed to the outside of the electronic device  100  between the first housing  110  and the second housing  120 . For example, the area in which the hinge cover  165  is exposed to the outside may be smaller than that in the fully folded state. The hinge cover  165  may include a curved surface. 
     When the electronic device  100  is in the unfolded state (e.g., the state in  FIG. 1 ), the first housing  110  and the second housing  120  may form an angle of 180 degrees (“180 degrees” shall be understood to include 180 degrees, substantially 180 degrees, or within 3 degrees of 180 degrees), and a first area  130   a , a folding area  130   c , and a second area  130   b  of the first display  130  may form the same plane, and may be disposed to be directed in the same direction. When the electronic device  100  is in the unfolded state, the first housing  110  may rotate at an angle of 360 degrees with respect to the second housing  120  to be reversely folded such that the second surface  112  and the fourth surface  122  face each other (an out-folding type). 
     When the electronic device  100  is in the folded state (e.g., the state in  FIG. 2 ), the first surface  111  of the first housing  110  and the third surface  121  of the second housing  120  may be disposed to face each other. The first housing  110  and the second housing  120  are vertically adjacent or stacked. In this case, the first area  130   a  and the second area  130   b  of the first display  130  may form a narrow angle (e.g., in the range of 0 degrees to 10 degrees) through the folding area  130   c , and may be disposed to face each other. At least a portion of the folding area  130   c  may be formed as a curved surface having a certain radius of curvature. When the electronic device  100  is in the intermediate state, the first housing  110  and the second housing  120  may be disposed at a certain angle. In this case, the first area  130   a  and the second area  130   b  of the first display  130  may form an angle greater than the folded state and less than the unfolded state, and the radius of curvature of the folding area  130   c  may be greater than that in the folded state. In some embodiments, the first housing  110  and the second housing  120  may form an angle to stop at a specified folding angle of between the folded state and the unfolded state through the hinge (e.g., the hinge  164  in  FIG. 3 ) (a free stop function). In some embodiments, the first housing  110  and the second housing  120  may operate while being pressed in the direction to be unfolded or in the direction to be folded based on a specified inflection angle through the hinge (e.g., the hinge  164  in  FIG. 3 ). 
     The electronic device  100  may include at least one of at least one display  130  or  151  disposed in or on a surface of the first housing  110  and/or the second housing  120 . The electronic device  100  may also include an input device  115 , sound output devices  127  and  128 , sensor modules  117   a ,  117   b , and  126 , camera modules  116   a ,  116   b , and  125 , a key input device  119 , an indicator (not shown), or a connector port  129 . In some embodiments, the electronic device  100  may exclude at least one of the elements, or may further include at least one of other elements. 
     The at least one display  130  or  151  may include a first display  130  (e.g., a flexible display) disposed to be supported by the third surface  121  of the second housing  120  from the first surface  111  of the first housing  110  through the hinge (e.g., the hinge  164  in  FIG. 3 ), and a second display  151  disposed to be visible to the outside through the fourth surface  122  in the inner space of the second housing  120 . The first display  130  may be mainly used in the unfolded state of the electronic device  100 , and the second display  151  may be mainly used in the folded state of the electronic device  100 . According to an embodiment, in the intermediate state, the electronic device  100  may use the first display  130  or the second display  151 , based on a folding angle of the first housing  110  and the second housing  120 . 
     According to certain embodiments, the first display  130  may be disposed in a space formed by a pair of housings  110  and  120 . For example, the first display  100  may be seated in a recess  101  formed by a pair of housings  110  and  120 , and may be disposed to substantially occupy most of the front surface of the electronic device  100 . The first display  130  may include a flexible display in which at least a portion thereof may be transformed into a flat or curved surface. The first display  130  may include a first area  130   a  facing the first housing  110 , a second area  130   b  facing the second housing  120 , and a folding area  130   c  that connects the first area  130   a  to second area  130   b  and faces the hinge (e.g., the hinge  164  in  FIG. 3 ). 
     The first area  130   a  of the first display  130  may substantially form the first surface  111  of the first housing  110 . The second area  130   b  of the first display  130  may substantially form the third surface  121  of the second housing  120 . 
     The areas of the first display  130  are only exemplary physical divisions by a pair of housings  110  and  120  and the hinge (e.g., the hinge  164  in  FIG. 3 ), and the first display  130  may be substantially displayed as a seamless full screen through a pair of housings  110  and  120  and the hinge (e.g., the hinge  164  in  FIG. 3 ). The first area  130   a  and the second area  130   b  may have an overall symmetrical shape or a partially asymmetrical shape based on the folding area  130   c.    
     According to certain embodiments, the electronic device  100  may include a first rear cover  140  disposed on the second surface  112  of the first housing  110  and a second rear cover  150  disposed on the fourth surface  122  of the second housing  120 . In some embodiments, at least a portion of the first rear cover  140  may be integrally formed with the first side member  113 . In some embodiments, at least a portion of the second rear cover  150  may be integrally formed with the second side member  123 . According to an embodiment, at least one of the first rear cover  140  and the second rear cover  150  may be formed through a substantially transparent plate (e.g., a glass plate including various coating layers, or a polymer plate) or an opaque plate. The first rear cover  140  may, for example, be formed by an opaque plate such as coated or tinted glass, ceramic, polymer, metal (e.g., aluminium, stainless steel (STS), or magnesium), or a combination of at least two of the above materials. The second rear cover  150 , for example, may be formed through a substantially transparent plate, such as, glass or polymer. Accordingly, the second display  151  may be disposed to be visible to the outside through the second rear cover  150  in the inner space of the second housing  120 . 
     The input device  115  may include a microphone  115 . In some embodiments, the input device  115  may include a plurality of microphones  115  disposed to be able to detect the direction of sound. The sound output devices  127  and  128  may include speakers  127  and  128 . The speakers  127  and  128  may include a call receiver  127  disposed through the fourth surface  122  of the second housing  120  and an external speaker  128  disposed through the side member of the second housing  120 . In some embodiments, the microphone  115 , the speakers  127  and  128 , and the connector  129  may be disposed in the spaces of the first housing  110  and/or the second housing  120 , and may be in contact with the external environment through at least one hole formed in the first housing  110  and/or the second housing  120 . In some embodiments, the holes formed in the first housing  110  and/or the second housing  120  may be used in common for the microphone  115  and the speakers  127  and  128 . In some embodiments, the sound output devices  127  and  128  may include a speaker (e.g., a piezo speaker) that operates without the holes formed in the first housing  110  and/or the second housing  120 . 
     The camera modules  116   a ,  116   b , and  125  may include a first camera device  116   a  disposed on the first surface  111  of the first housing  110 , a second camera device  116   b  disposed on the second surface  112  of the first housing  110 , and/or a third camera device  125  disposed on the fourth surface  122  of the second housing  120 . The electronic device  100  may include a flash  118  disposed near the second camera device  116   b . The flash  118  may include, for example, a light-emitting diode or a xenon lamp. The camera devices  116   a ,  116   b , and  125  may include one or more lenses, an image sensor, and/or an image signal processor. In some embodiments, at least one of the camera devices  116   a ,  116   b , and  125  may include two or more lenses (wide-angle and telephoto lenses) and image sensors, and may be disposed together on either side of the first housing  110  and/or the second housing  120 . 
     The sensor modules  117   a ,  117   b , and  126  may produce an electrical signal or a data value corresponding to the internal operation state of the electronic device  100  or the external environmental state. The sensor modules  117   a ,  117   b , and  126  may include a first sensor module  117   a  disposed on the first surface  111  of the first housing  110 , a second sensor module  117   b  disposed on the second surface  112  of the first housing  110 , and a third sensor module  126  disposed on the fourth surface  122  of the second housing  120 . In some embodiments, the sensor modules  117   a ,  117   b , and  126  may include at least one of a gesture sensor, a grip sensor, a color sensor, an infrared (IR) sensor, an illumination sensor, an ultrasonic sensor, an iris recognition sensor, or a distance detection sensor (a TOF sensor or a RiDAR scanner). 
     The electronic device  100  may further include at least one of non-illustrated sensor modules, for example, an atmospheric pressure sensor, a magnetic sensor, a biometric sensor, a temperature sensor, a humidity sensor, and a fingerprint recognition sensor. In some embodiments, the fingerprint recognition sensor may be disposed through at least one of the first side member  113  of the first housing  110  and/or the second side member  123  of the second housing  120 . 
     The key input device  119  may be disposed to be exposed to the outside through the first side member  113  of the first housing  110 . In some embodiments, the key input device  119  may be disposed to be exposed to the outside through the second side member  123  of the second housing  120 . The electronic device  100  may exclude some or all of the key input devices  119  mentioned above, and the excluded key input device  119  may be implemented in another form such as a soft key in the at least one display  130  or  151  or the like. As another embodiment, the key input device  119  may be implemented using a pressure sensor included in the at least one display  130  or  151 . 
     The connector port  129  may accommodate a connector (e.g., a USB connector or an IF module (interface connector port module)) for transmitting and receiving power and/or data to and from an external electronic device. In some embodiments, the connector port  129  may further perform a function of transmitting and receiving an audio signal to and from an external electronic device, or may further include a separate connector port (e.g., an ear jack hole) for performing a function of transmitting and the receiving an audio signal. 
     At least one camera device  116   a  or  125  among the camera devices  116   a ,  116   b , and  125 , at least one sensor module  117   a  or  126  among the sensor modules  117   a ,  117   b , and  126 , and/or the indicator may be disposed to be exposed through the at least one display  130  or  151 . For example, at least one camera device  116   a  or  125 , at least one sensor module  117   a  and  126 , and/or the indicator may be disposed below an activation area (the display area) of the displays  130  and  140  in the inner space of the at least one housing  110  or  120 , and may be disposed to be exposed to the external environment through an opening that is perforated to the cover member (e.g., a window layer (not shown) and/or the second rear cover  150  of the first display  130 ). In another embodiment, some camera devices or sensor modules  104  may be disposed to perform their own functions without being visually exposed through the display. For example, the area of the display  101  (e.g., the display panel) facing the camera device and/or the sensor module may not require the perforated opening. 
       FIG. 3  is an exploded perspective view of an electronic device  100  according to certain embodiments of the disclosure. 
     Referring to  FIG. 3 , the electronic device  100  may include a first display  130 , a second display  151 , a support member assembly  160 , at least one printed circuit board  170 , a first housing  110 , a second housing  120 , a first rear cover  140 , and a second rear cover  150 . 
     According to certain embodiments, the first display  130  may include a display panel  131  (e.g., a flexible display panel) and one or more plates  132  or layers on which the display panel  131  (e.g., the flexible display panel) is placed. According to an embodiment, one or more plates  132  may include a conductive plate (e.g., a Cu sheet or a SUS sheet) disposed between the display panel  131  and the support member assembly  160 . According to an embodiment, one or more plates  132  may be formed to have substantially the same area as the first display  130 , and the area facing the folding area  130   c  of the first display  130   c  may be formed to be bendable. According to an embodiment, one or more plates  132  may include at least one sub-material layer (e.g., a graphite member) disposed on the rear surface of the display panel  131 . According to an embodiment, one or more plates  132  may be formed in a shape corresponding to the display panel  131 . 
     According to certain embodiments, the second display  151  may be disposed in the space between the second housing  120  and the second rear cover  150 . The second display  151  may be disposed to be visible to the outside through substantially the entire area of the second rear cover  150  in the space between the second housing  120  and the second rear cover  150 . 
     According to certain embodiments, the support member assembly  160  may include a first support member  161  (e.g., a first support plate), a second support member  162  (e.g., a second support plate), a hinge  164  disposed between the first support member  161  and the second support member  162 , a hinge cover  165  that covers the hinge  164  when viewed from the outside, and at least one wiring member  163  (e.g., a flexible printed circuit board (FPCB)) crossing the first support member  161  and the second support member  162 . The support member assembly  160  may be disposed between one or more plates  132  and at least one printed circuit board  170 . The first support member  161  may be disposed between the first area  131   a  of the first display  130  and the first printed circuit board  171 . The second support member  162  may be disposed between the second area  131   b  of the first display  130  and the second printed circuit board  172 . According to an embodiment, at least one wiring member  163  and at least a portion of the hinge  164  may be disposed inside the support member assembly  160 . At least one wiring member  163  may be disposed in the direction (e.g., the x-axis direction) crossing the first support member  161  and the second support member  162 . According to an embodiment, at least one wiring member  163  may be disposed in the direction (e.g., the x-axis direction) perpendicular to the folding axis (e.g., the y-axis or the folding axis A in  FIG. 1 ) of the folding area  130   c.    
     According to certain embodiments, at least one printed circuit board  170  may include a first printed circuit board  171  disposed to face the first support member  161  and a second printed circuit board  172  disposed to face the second support member  162 . The first printed circuit board  171  and the second printed circuit board  172  may be disposed in the inner space formed by the support member assembly  160 , the first housing  110 , the second housing  120 , the first rear cover  140 , and/or the second rear cover  150 . The first printed circuit board  171  and the second printed circuit board  172  may include a plurality of electronic components disposed to implement various functions of the electronic device  100 . 
     According to certain embodiments, the electronic device may include, in the first space of the first housing  110 , a first printed circuit board  171  disposed in the space formed through the first support member  161 , a first battery  191  disposed in the position facing a first swelling hole  1611  of the first support member  161 , at least one camera device  182  (e.g., the first camera device  116   a  and/or the second camera device  116   b  in  FIG. 1 ), or at least one sensor module  181  (e.g., the first sensor module  117   a  and/or the second sensor module  117   b  in  FIG. 1 ). According to an embodiment, a second printing circuit board  172  disposed in a second space formed through the second support member  162  and a second battery  192  disposed in the position facing a second swelling hole  1621  of the second support member  162  may be included in a second space of the second housing  120 . The first housing  110  and the first support member  161  may be integrally formed. The second housing  120  and the second support member  162  may also be integrally formed. 
     According to certain embodiments, the first housing  110  may include a first rotation support surface  114 , and the second housing  120  may include a second rotation support surface  124  corresponding to the first rotation support surface  114 . The first rotation support surface  114  and the second rotation support surface  124  may include a curved surface corresponding to (naturally connected to) the curved surface included in the hinge cover  165 . According to an embodiment, when the electronic device  100  is in the unfolded state, the first rotation support surface  114  and the second rotation support surface  124  may cover the hinge cover  165  such that the hinge cover  165  is not exposed or is minimally exposed through the rear surface of the electronic device  100 . According to an embodiment, when the electronic device  100  is in the folded state, the first rotation support surface  114  and the second rotation support surface  124  may rotate along the curved surface included in the hinge cover  165 , thereby maximally exposing the hinge cover  165  through the rear surface of the electronic device  100 . 
       FIG. 4A  discloses the front surface of the electronic device  300  when the electronic device  300  is in the open state. The electronic device  300  includes a first housing  310  and a second housing  320 . A hinge  364  allows the first housing  310  and the second housing  320  to fold about axis A 1 . 
     A flexible display  400  is disposed on the surface of the first housing  310  and the second housing  320 . When the electronic device  300  folds, the flexible display  400  deforms. 
       FIG. 5  discloses the flexible display  400 . The flexible display  400  includes a window layer  410  disposed above a display layer  430 . The window layer  410  includes a polymer layer  411  disposed above a glass layer  412 . 
       FIG. 4A  is an exploded perspective view of an electronic device  300  including a flexible display  400  according to certain embodiments of the disclosure.  FIG. 4B  is a diagram illustrating configuration for each area of an electronic device  300  according to certain embodiments of the disclosure. 
     The electronic device  300  in  FIGS. 4A and 4B  may be at least partially similar to the electronic device  100  in  FIG. 1 , or may further include other embodiments of the electronic device. 
     Referring to  FIGS. 4A and 4B , the electronic device  300  (e.g., the electronic device  100  in  FIG. 1 ) may include a first housing  310  (e.g., the first housing  110  in  FIG. 1 ) (e.g., a first housing structure) that includes a first surface  311  (e.g., the first surface  111  in  FIG. 1 ), a second surface  312  (e.g., the second surface  112  in  FIG. 1 ) directed in the opposite direction of the first surface  311 , and a first side member  313  (e.g., the first side member  113  in  FIG. 1 ) surrounding a first space between the first surface  311  and the second surface  312 . The electronic device  300  may include a second housing  320  (e.g., the second housing  120  in  FIG. 1 ) (e.g., a second housing structure) that includes a third surface  321  (e.g., the third surface  121  in  FIG. 1 ) directed in the same direction as the first surface  311  in the unfolded state, a fourth surface  322  (e.g., the fourth surface  122  in  FIG. 1 ) directed in the same direction as the second surface  312 , and a second side member  323  (e.g., the second side member  123  in  FIG. 1 ) surrounding a second space between the third surface  321  and the fourth surface  322 . The first housing  310  and the second housing  320  may be installed to be foldable with respect to each other around the folding axis A 1  through the hinge  364  (e.g., the hinge  164  in  FIG. 3 ). For example, the electronic device  300  may maintain the folded or unfolded state by rotating the first housing  310  and the second housing  320  with respect to each other through the hinge  364 . The first surface  311  and the third surface  321  may face each other in the folded state of the electronic device  300 , and the first surface  311  and the third surface  321  may be directed in the same direction in the unfolded state thereof. According to some embodiments, the first surface  311  and the third surface  321  may be directed in the opposite directions in the folded state of the electronic device  300 , and the first surface  311  and the third surface  321  may be directed in the same direction in the unfolded state thereof. The electronic device  300  may include a flexible display  400  (e.g., the first display  130  in  FIG. 1 ) disposed to at least partially cross the first surface  311  and the third surface  321 . The flexible display  400  may be disposed to be supported by at least a portion of the first housing  310 , the hinge  364 , and the second housing  320 . 
     The electronic device  300  (e.g., the electronic device  100  in  FIG. 1 ) may include a first area h 1  facing the first housing  310 , a second area h 2  facing the second housing  320 , and a folding area h 3  facing the hinge  364 . The electronic device  300  may operate such that the first housing  310  corresponding to the first area h 1  may be folded or unfolded with respect to the second housing  320  corresponding to the second area h 2  through the hinge  364  corresponding to the folding area h 3 . 
     According to certain embodiments, the electronic device  300  may include at least one protecting frame  340  or  350  (e.g., a decorative member or a decor) disposed on top of the flexible display  400 . According to an embodiment, at least one protecting frame  340  or  350  may include a first protecting frame  340  disposed on top of the flexible display  400  in the first area h 1  and a second protecting frame  350  disposed on top of the flexible display  400  in the second area h 2 . The protecting frames  340  and  350  may be formed of a polymer material or a metal material, and may be disposed in the respective housings  310  and  320  through at least one of bonding, taping, fusion, or structural coupling. 
     The flexible display  400  may include a first edge  4001  facing at least a portion of the first housing  310 , a second edge  4002  facing at least a portion of the second housing  320 , a third edge  4003  that connects one end of the first edge  4001  and one end of the second edge  4002 , and a fourth edge  4004  that connects the opposite end of the first edge  4001  and the opposite end of the second edge  4002 . The first edge  4001  of the flexible display  400  and at least a portion of the third edge  4003  and fourth edge  4004  may be disposed between the first housing  310  and the first protecting frame  340  so as not to be visible to the outside. The second edge  4002  of the flexible display  400  and at least a portion of the third edge  4003  and fourth edge  4004  may be disposed between the second housing  320  and the second protecting frame  350  so as not to be visible to the outside. 
     Static electricity may be introduced into the electronic device  300  through the gaps between the flexible display  400  and the first protecting frame  340  and/or between the flexible display  400  and the second protecting frame  350 . The introduced static electricity may be guided to at least one conductive structure electrically connected to the main ground of the electronic device  300  through a static electricity guide structure according to the exemplary embodiments of the disclosure, thereby preventing malfunction and damage of the display panel (e.g., the display panel  430  in  FIG. 5 ). 
     The pair of protecting frames  340  and  350  may be omitted from the folding area h 3  corresponding to the hinge  364  for the folding and unfolding operation of the first housing  310  and the second housing  320  around the hinge  364 . The electronic device  300  may include a protecting structure  500  disposed in order to protect at least a portion of the third edge  4003  and at least a portion of the fourth edge  4004  of the flexible display exposed to the outside in the folding area h 3 . The edges of the flexible display  400  exposed through the folding area h 3  may be disposed to be at least partially invisible to the outside through the protecting structure  500 . The protecting structure  500  may include a support body  510  disposed to be supported by at least a portion of the hinge  364  and a blocking member  520  disposed to be supported by the support body  510  and to at least partially hide the edges of the flexible display  400  from the outside. In some embodiments, the support body  510  may include wing structures rotatably installed on the left and right sides of the support body  510  in order to support the film type blocking member  520 . 
     An electronic device (e.g., the electronic device  100  in  FIG. 1 ) according to certain embodiments of the disclosure may include a first housing (e.g., the first housing  310  in  FIG. 4A ), a second housing (e.g., the second housing  320  in  FIG. 4A ), a hinge (e.g., the hinge  164  in  FIG. 3 ) disposed between the first housing  310  and the second housing  320  such that the second housing  320  is foldable from one end of the first housing  310 , and a flexible display supported by the first housing  310  and the second housing  320 , and including a display panel (e.g., the display panel  430  in  FIG. 5 ) and a glass layer (e.g., the glass layer  412  in  FIG. 5 ) disposed in a first direction from the display panel  430 , wherein the glass layer  412  may include a bending portion (e.g., the bending portion  710  in  FIG. 6 ) configured to be flat in an unfolded state in which the first housing  310  and the second housing  320  are disposed in a straight line side by side, and be bent in a folded state in which the first housing  310  and the second housing  320  face each other, and flat portions (e.g., the flat portions  720  in  FIG. 6 ) configured to be flat in the unfolded state and the folded state, and including a first flat portion (e.g., the first flat portion  721  in  FIG. 7 ) adjacent to the bending portion  710  to form a boundary and a second flat portion (e.g., the second flat portion  722  in  FIG. 7 ) disposed to extend from the first flat portion  721  to an edge of the glass layer  412 , wherein the glass layer  412  may include a glass member (e.g., the glass member  610  in  FIG. 6 ), wherein the glass member  610  may have a first thickness in the second flat portion  722 , have a second thickness at the center of the bending portion  710 , and have a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion  721  and the center of the bending portion  710 , and wherein the thickness of the glass member  610  gradually decreases from the first flat portion  721  to the center of the bending portion  710  to form a concave portion (e.g., the concave portion  630  in  FIG. 7 ). 
     The glass member  610  may include UTG (ultra-thin glass), and the width of the concave portion  630  may be greater than the width of the bending portion  710 . 
     According to an embodiment, an inclined surface may be formed on the surface of the concave portion  630 , and when the angle of the inclined surface with respect to the surface of the second flat portion  722  is defined as θ, tan θ, which is the slope of the inclined surface, may be less than or equal to 1/10. 
     The first thickness may be double the second thickness or more. 
     The concave portion  630  may be formed in the first direction from the glass layer  412 . 
     The concave portion  630  may be formed in a second direction opposite the first direction from the glass layer  412 . 
     According to an embodiment, regular irregularities may be formed on the inclined surface of the concave portion  630 . 
     According to an embodiment, irregular irregularities may be formed on the inclined surface of the concave portion  630 . 
     The flexible display may further include a polarization layer disposed between the display panel  430  and the glass layer  412 , a shock absorption layer disposed between the polarization layer and the glass layer  412 , and a polymer layer disposed in the first direction from the glass layer  412 , wherein the area of a first adhesive disposed between the glass layer  412  and the polymer layer may be greater than or equal to the area of the glass layer  412 , and wherein the area of a second adhesive disposed between the glass layer  412  and the shock absorption layer may be greater than or equal to the area of the glass layer  412 . 
     The area of the first adhesive disposed between the glass layer  412  and the polymer layer may be greater than the area of the glass layer  412 , the area of the second adhesive disposed between the glass layer  412  and the shock absorption layer may be equal to the area of the glass layer  412 , and, at at least one edge of the flexible display, the end of the first adhesive may protrude from the end of the glass layer  412  in a third direction perpendicular to the first direction, and the end of the second adhesive and the end of the glass layer  412  may be disposed to form a straight line. 
     The area of the first adhesive disposed between the glass layer  412  and the polymer layer may be greater than the area of the glass layer  412 , and the area of the second adhesive disposed between the glass layer  412  and the shock absorption layer may be greater than the area of the glass layer  412 , and at at least one edge of the flexible display, the end of the first adhesive may protrude from the end of the glass layer  412  in a third direction perpendicular to the first direction and the end of the second adhesive may protrude in the third direction from the end of the glass layer  412 . 
     The area of the first adhesive disposed between the glass layer  412  and the polymer layer may be the same as the area of the glass layer  412 , and the area of the second adhesive disposed between the glass layer  412  and the shock absorption layer may be greater than the area of the glass layer  412 , and at at least one edge of the flexible display, an end of the first adhesive and an end of the glass layer  412  may be disposed to form a straight line and an end of the second adhesive may protrude from the end of the glass layer  412  in a third direction perpendicular to the first direction. 
     According to an embodiment, an adhesive member may be formed in the third direction from the end of the glass layer  412  so as to correspond between the first adhesive and the shock absorption layer. 
     The area of the shock absorption layer may be greater than the area of the display panel  430 , and the area of a third adhesive disposed between the shock absorption layer and the display panel  430  may be greater than the area of the display, and at at least one edge of the flexible display, an end of the shock absorption layer and an end of the third adhesive may protrude from an end of the display panel  430  in a third direction perpendicular to the first direction. 
     The high-temperature adhesion of the third adhesive may be less than the high-temperature adhesion of each of the first adhesive and the second adhesive. 
     The third adhesive may include a photoinitiator component to react to UV (ultraviolet ray) light or laser in a specified wavelength band, thereby lowering the adhesion. 
     The thickness of the second adhesive may be less than the thickness of the first adhesive. 
     Glass for a flexible display of a foldable electronic device  100  according to certain embodiments of the disclosure may include a bending portion  710  configured to be bent in a folded state of the foldable electronic device  100 , and flat portions  720  configured to be flat in an unfolded state and the folded state of the foldable electronic device  100 , and including a first flat portion  721  adjacent to the bending portion  710  to form a boundary and a second flat portion  722  disposed to extend from the first flat portion  721  to an edge of the glass, wherein the glass may include a glass member  610 , wherein the glass member  610  may have a first thickness in the second flat portion  722 , have a second thickness at the center of the bending portion  710 , and has a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion  721  and the center of the bending portion  710 , and wherein the thickness of the glass member  610  may gradually decrease from the first flat portion  721  to the center of the bending portion  710  to form a concave portion  630 . 
     The glass member  610  may include UTG (ultra-thin glass), and the width of the concave portion  630  may be greater than the width of the bending portion  710 . 
     According to an embodiment, an inclined surface may be formed on the surface of the concave portion  630 , and when the angle of the inclined surface with respect to the surface of the second flat portion  722  is defined as θ, tan θ, which is the slope of the inclined surface, is less than or equal to 1/10. 
       FIG. 5  is a perspective view illustrating a stacked structure of a flexible display  400  according to certain embodiments of the disclosure. 
     The flexible display  400  according to exemplary embodiments of the disclosure may include a UB (unbreakable) type OLED display (e.g., a curved display). The flexible display  400  according to exemplary embodiments of the disclosure may include a Y-OCTA (YOUM-on cell touch AMOLED (active matrix organic light-emitting diode)) type display. 
     The flexible display  400  in  FIG. 5  may be at least partially similar to the first display  130  in  FIG. 1 , or may further include other embodiments. 
     Referring to  FIG. 5 , the flexible display  400  (e.g., the first display  130  in  FIG. 1 ) may include a window layer  410 , a polarization layer (POL (polarizer))  420  (e.g., a polarizing film) sequentially disposed on the rear surface of the window layer  410 , a display panel  430 , a polymer member  440 , and a conductive plate  450 . The window layer  410  may include a polymer layer  411  (e.g., PET (polyethylene terephthalate)) and a glass layer  412  (e.g., UTG (ultra-thin glass)) laminated with the polymer layer  411 . The polymer layer may include PET or polyimide. The glass layer may include UTG (ultra-thin glass). The polymer layer  411  may protect other layers (e.g., the glass layer  412 , the polarization layer  420 , and the display panel  430 ) included in the flexible display  400  from an external impact. For example, the polymer layer  411  may protect the glass layer  412  and prevent shattering when cracks occur in the glass layer  412 . The polymer layer  411  may include a glass material or include a film layer or a coating layer. The polymer layer  411  may include a flexible material. The polymer layer  411  may be formed of a transparent material having high light-transmittance. 
     The flexible display  400  may include a color filter (not shown) in place of the polarization layer  420 . For example, the color filter may perform the same or similar role as the polarization layer  420 . For example, the electronic device  100  that does not include a color filter may be defined as a COE (color filter on encapsulation) type electronic device  100 . The color filter may execute the function of the polarization layer  420  or play the role thereof in the COE type electronic device  100 , thereby improving transmittance and reducing the thickness of the flexible display  400  by about 100 μm to about 150 μm. 
     The flexible display  400  may further include a touch panel that is not shown. The touch panel may be formed between the polarization layer  420  and the glass layer  412 . In another embodiment, the touch panel may be formed between the display panel  430  and the polarization layer  420 . 
     The window layer  410 , the polarization layer  420 , the display panel  430 , the polymer member  440 , and the conductive plate  450  may be disposed to cross at least a portion of a first surface (e.g., the first surface  111  in  FIG. 1 ) of a first housing (e.g., the first housing  110  in  FIG. 1 ) and a third surface (e.g., the third surface  121  in  FIG. 1 ) of a second housing (e.g., the second housing  120  in  FIG. 1 ). The window layer  410 , the polarization layer  420 , the display panel  430 , the polymer member  440 , and the conductive plate  450  may be attached to each other through adhesives P 1 , P 2 , and P 3 . For example, the adhesives P 1 , P 2 , and P 3  may include at least one of an OCA (optical clear adhesive), a PSA (pressure sensitive adhesive), a heat-responsive adhesive, a general adhesive, and a double-sided tape. The flexible display  400  may include another adhesive member (e.g., a double-sided tape or a waterproof member) that is at least partially disposed on one surface of the conductive plate  450 . The flexible display  400  may be attached to a support member assembly (e.g., the support member assembly  160  in  FIG. 3 ) of the electronic device (e.g., the electronic device  100  in  FIG. 3 ) through another adhesive member. 
     A dark color (e.g., black) may be applied to the polymer member  440  to help display the background when the display is turned off. The polymer member  440  may include a cushion for absorbing an impact from the outside of the electronic device, thereby preventing the flexible display  400  from being damaged. In some embodiments, in order to waterproof the flexible display  400 , the polymer member  440  may be removed or disposed under the conductive plate  450 . 
     The conductive plate  450  may be used to help reinforce rigidity of the electronic device, shield ambient noise, and dissipate heat emitted from surrounding heat emission components. The conductive plate  450  may include at least one of SUS (steel use stainless) (e.g., STS (stainless steel)), Cu, Al, or CLAD (e.g., a stacked member in which SUS and Al are alternately disposed). In another embodiment, the conductive plate  450  may include other alloy materials. According to an embodiment, a portion facing the first housing (e.g., the first housing  310  in  FIG. 4A ) of the electronic device (e.g., the electronic device  300  in  FIG. 4A ) and a portion facing the second housing (e.g., the second housing  320  in  FIG. 4A ) thereof may be connected to a bendable portion (e.g., a portion provided with bendability through a lattice structure including a plurality of openings and/or slits), which is formed at the portion facing the hinge (e.g., the hinge  364  in  FIG. 4A ), so that the conductive plate  450  may be integrally formed. In another embodiment, in the conductive plate  450 , a portion facing the first housing (e.g., the first housing  310  in  FIG. 4A ) and a portion facing the second housing (e.g., the second housing  320  in  FIG. 4A ), excluding a portion facing the hinge (e.g., the hinge  364  in  FIG. 4A ), may be formed separately from each other. According to certain embodiments, the flexible display  400  may further include reinforcement plates  460  made of a metal material and disposed under the conductive plate for reinforcement of rigidity. The reinforcement plates  460  may include a first reinforcement plate  461  facing the first housing (e.g., the first housing  310  in  FIG. 4A ) and a second reinforcement plate  462  facing the second housing (e.g., the second housing  320  in  FIG. 4A ). 
     The flexible display  400  may include at least one functional member disposed between the polymer member  440  and the conductive plate  450 . The functional member may include a graphite sheet for heat dissipation, a force touch FPCB, a fingerprint sensor FPCB, an antenna radiator for communication, a heat dissipation sheet, conductive/non-conductive tapes, or an open cell sponge. The functional member, when it is bendable, may be disposed from the first housing (e.g., the first housing  310  in  FIG. 4A ) to at least a portion of the second housing (e.g., the second housing  320  in  FIG. 4A ) through the hinge (e.g., the hinge  364  in  FIG. 4A ). In another embodiment, the flexible display  400  may further include a detection member for detecting an input by an electromagnetic induction type writing member. The detection member may include a digitizer. 
     The stacked structure and stacked order of the flexible display  400  shown in  FIG. 5  may be variously modified. For example, at least some layers may be further inserted into the stacked structure or stacked order of the flexible display  400  shown in  FIG. 5 , or at least some layers may be omitted therefrom. 
       FIGS. 6 and 7  illustrate the glass layer  412  when the electronic device is in the folded state ( FIG. 6 ) and the unfolded state ( FIG. 7 ). The glass layer  412  includes flat portions  720  and a bending portion  710 . In the unfolded state, bending portion  710 , the glass member  610  of the glass layer  412  is concave with a thickness t 2  at the center. The thickness of the glass member  610  widens (e.g., t 3 ) moving from the center towards the flat portions  720 . Filling member  620  corresponds to the shape of the glass member  610 , such that the bottom surface of the electronic device is flat. In  FIG. 8 , the glass layer  610  has a width of t 1  at the edge of the electronic device when the electronic device is in the unfolded state. However, glass layer has a width of t 5 . The difference between width t 1  and width t 5  is a t 4  thick layer of the filling member. 
       FIG. 6  is a cross-sectional view schematically illustrating a glass layer  412  when an electronic device  100  is in a folded state according to an embodiment.  FIG. 7  is a cross-sectional view schematically illustrating a glass layer  412  when an electronic device  100  is in an unfolded state according to an embodiment.  FIG. 8  is a cross-sectional view schematically illustrating a glass layer  412  according to another embodiment. 
     The glass layer  412  shown in  FIGS. 6 to 8  may be at least partially similar to the glass layer  412  shown in  FIG. 5 , or may include other embodiments. Hereinafter, only the characteristics of the glass layer  412  that were not described in  FIG. 5  or differ therefrom will be described with reference to  FIGS. 6 to 8 . 
     Referring to  FIGS. 6 to 8 , the glass layer  412  according to an embodiment may be defined as including flat portions  720  and a bending portion  710 . For example, the entire area of the glass layer  412  may be divided into flat portions  720  and a bending portion  710 . 
     The flat portion  720  of the glass layer  412  may be an area that is flat when the electronic device  100  is in the folded state and is flat when the electronic device  100  is in the unfolded state. For example, the flat portion  720  may always be a flat area, regardless of the shape of the electronic device  100 . The curvature of the surface of the flat portion  720  may remain constant irrespective of the shape of the electronic device  100 . 
     The bending portion  710  of the glass layer  412  may be an area that is bent when the electronic device  100  is in the folded state and is flat when the electronic device  100  is in the unfolded state. For example, the bending portion  710  may be an area that is bent only when the electronic device  100  is in the folded state. The curvature of bending portion  710  may vary when switching from the unfolded state to the folded state or from the folded state to the unfolded state. The bending portion  710  of the glass layer  412  may substantially overlap at least a portion of the folding area (e.g., the folding area  130   c  in  FIG. 1 ) of the electronic device  100 . 
     The bending portion  710  may be positioned close to the center c of the glass layer  412 . For example, as the bending portion  710  is positioned at the center c in the glass layer  412 , the flat portions  720  of the glass layer  412  may be disposed on both sides of the bending portion  710 . The center c of the bending portion  710  may be substantially the same as the center c of the glass layer  412 . 
     The flat portion  720  of the glass layer  412  may be divided into an area that is adjacent to the bending portion  710  to form a boundary and an area that is not adjacent to the bending portion  710 . The flat portion  720  may include a first flat portion  721  adjacent to the bending portion  710 , thereby forming a boundary, and a second flat portion  722  disposed to extend from the first flat portion  721  to the edge of the glass layer  412 . 
     According to an embodiment, as the bending portion  710  is positioned at the center c in the glass layer  412 , the first flat portion  721  of the flat portions  720  may include a first portion  721   a  adjacent to one end of the bending portion  710  and a second portion  721   b  adjacent to the opposite end of the bending portion  710 . 
     The second flat portion  722  of the flat portions  720  may include a third portion  722   a  extending from the first portion  721   a  to one edge of the glass layer  412  and a fourth portion  722   b  extending from the second portion  721   b  to the opposite edge of the glass layer  412 . 
     According to certain embodiments, the stacked structure of the glass layer  412  may include a glass member  610  and a filling member  620 . 
     The glass member  610  may include a polymer film or a glass material. The glass member  610  may include PI, PET, or UTG (ultra-thin glass). 
     The filling member  620  may be formed of a synthetic resin (e.g., resin), and the synthetic resin may include, for example, at least one of acryl, epoxy, silicone, and urethane. The filling member  620  may include an optical clear resin (OCR). The filling member  620  may be formed of a material having higher ductility than the glass member  610 . 
     The glass member  610  may be disposed to be directed in a first direction (z-direction) in which the front surface (e.g., the first surface  111  and the third surface  121  in  FIG. 1 ) of the electronic device  100  is exposed in the unfolded state. The filling member  620  may be disposed in a second direction (-z-direction) opposite the first direction (z-direction) from the glass member  610 . The filling member  620  may be formed to overlap at least a portion of the glass member  610  or to overlap the entire area of the glass member  610 . 
     According to certain embodiments, the thickness of the glass member  610  may be designed to not be constant and to decrease as it is closer to the center c of the bending portion  710 . The glass member  610  may have a first thickness t 1  in the flat portions  720  of the glass layer  412  such that the thickness starts to decrease from the first flat portion  721  of the flat portions  720  to a second thickness t 2  (e.g., a minimum thickness) at the center c of the bending portion  710 . For example, the glass member  610  may have a second thickness t 2  (e.g., a minimum thickness) at the center c of the bending portion  710 , and have a third thickness t 3 , which is less than the first thickness t 1  and greater than the second thickness t 2 , in the section between the first flat portion  721  of the flat portion  720  and the center c of the bending portion  710 . 
     The first thickness t 1  may be double the second thickness t 2  or more. For example, the second thickness t 2  of the glass member  610  corresponding to the center c of the bending portion  710  may be the half of the first thickness t 1  of the glass member  610 , corresponding to the second flat portion  722 , or less. 
     According to an embodiment, since the thickness of the glass member  610  decreases from the first flat portion  721  of the flat portions  720  to the center c of the bending portion  710 , the glass member  610  may have an inclined surface  631  formed in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 . According to an embodiment, since the thickness of the glass member  610  decreases from the first flat portion  721  of the flat portions  720  to the center c of the bending portion  710 , the glass member  610  may have a concave portion  630  formed in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 , and the surface of the concave portion  630  may include the inclined surface  631 . 
     The concave portion  630  of the glass member  610  may be disposed to be directed in the second direction (-z-direction). For example, the concave portion  630  of the glass member  610  may be disposed to face the polarization layer  420  or the display panel  430  in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 . 
     The electronic device  100  according to certain embodiments is able to reduce the user&#39;s visibility of the boundary portion of the folding area  130   c  and reduce cracks of the glass member  610  because the glass member  610  includes the concave portion  630 . A portion in which the concave portion  630  of the glass member  610  is formed (e.g., a portion in which the inclined surface  631  is formed) is not limited to the bending portion  710 , and may extend to a portion of the flat portion  720  (e.g., the first flat portion  721  of the flat portions  720 ), so that the electronic device  100  according to certain embodiments is able to further reduce the user&#39;s visibility of the boundary of the folding area  130   c . The width w of the concave portion  630  may be greater than the width of the bending portion  710 . 
     According to an embodiment, in the concave portion  630  of the glass member  610 , the slope of the inclined surface  631  may have a value less than or equal to about 1/10. For example, assuming that the angle of the inclined surface  631  with respect to the rear surface of the glass member  610  (e.g., the surface of the glass member  610  that faces in the second direction (-z-direction)) is defined as θ, tan θ may have a value less than or equal to about 1/10. 
     According to another embodiment, as shown by a dotted line  791  in  FIG. 7 , the thickness of the glass member  610  may be maintained constant to have the second thickness t 2  in the entire area of the bending portion  710 , and may gradually increase from the first flat portion  721  of the flat portions  720  to the third thickness t 3  that is greater than the second thickness t 2  and less than the first thickness t 1 . For example, as shown by dotted line  791  in  FIG. 7 , the glass member  610  may have the inclined surface  631  in the first flat portion  721  of the flat portions  720 . 
     The glass layer  412  may include a filling member  620  filling the concave portion  630  of the glass member  610 . For example, since the concave portion  630  of the glass member  610  is disposed to face the polarization layer  420  or the display panel  430 , the filling member  620  may be formed in the second direction (-z-direction) of the glass member  610 . The filling member  620  may function as a flattening film to make the thickness of the glass layer  412  constant. The overall thickness of the glass layer  412  may be constant in the flat portions and the bending portion  710  because the filling member  620  fills the concave portion  630  of the glass member  610 . For example, as shown in  FIG. 7 , the overall thickness of the glass layer  412  may be the first thickness t 1 , regardless of the area of the glass layer  412 . 
     According to another embodiment, as shown in  FIG. 8 , the filling member  620  of the glass layer  412  may be formed to correspond to the entire area of the glass member  610 , as well as filling the concave portion  630 . For example, the filling member  620  may be disposed to extend from the concave portion  630  to the edge of the glass member  610 . In this case, the thickness of the filling member  620  of the glass layer  412  may be a fourth thickness t 4  in the flat portion  720  of the glass layer  412  (e.g., the second flat portion  722  of the flat portions  720 ). According to the embodiment shown in  FIG. 8 , the overall thickness of the glass layer  412  may be a fifth thickness t 5 , which is the sum of the first thickness t 1  and the fourth thickness t 4 , regardless of the area of the glass layer  412 . 
       FIG. 9  is a cross-sectional view illustrating irregularities  911  formed on a glass layer  412  according to an embodiment. 
     The glass layer  412  illustrated in  FIG. 9  may be at least partially similar to the glass layer  412  shown in  FIGS. 5 to 8 , or may include other embodiments. Hereinafter, only the characteristics of the glass layer  412  that were not described in  FIGS. 5 to 8  or differ therefrom will be described with reference to  FIG. 9 . 
     Referring to  FIG. 9 , in the glass member  610  according to an embodiment, a plurality of irregularities  911  may be formed on the surface of the concave portion  630 . For example, the plurality of irregularities  911  may be formed regularly or irregularly by physical micro-pattern processing or chemical etching. Surface treatment may be performed on the glass member  610  according to certain embodiments such that a plurality of irregularities  911  is formed on the surface of the concave portion  630 , thereby inducing diffused reflection of light. The electronic device  100  according to certain embodiments may further reduce the user&#39;s visibility of the boundary of a folding area (e.g., the folding area  130   c  in  FIG. 1 ) using diffused reflection of light by the plurality of irregularities  911 . 
       FIG. 10  is a cross-sectional view schematically illustrating a glass layer  412  according to another embodiment.  FIG. 11  is a cross-sectional view schematically illustrating a glass layer  412  according to another embodiment.  FIG. 12  is a cross-sectional view schematically illustrating a glass layer  412  according to another embodiment. 
     The glass layer  412  illustrated in  FIGS. 10 to 12  may be at least partially similar to the glass layer  412  shown in  FIGS. 5 to 9 , or may include other embodiments. Hereinafter, only the characteristics of the glass layer  412  that were not described in  FIGS. 5 to 9  or differ therefrom will be described with reference to  FIGS. 10 to 12 . 
     Referring to  FIGS. 10 to 12 , a glass member  610  according to another embodiment may be disposed such that a concave portion  1130  faces in the first direction (z-direction), instead of the second direction (-z-direction). For example, unlike the glass member  610  shown in  FIGS. 6 to 8 , the glass member  610  shown in  FIG. 10  may be disposed such that the concave portion  1130  faces in the first direction (z-direction). 
     According to an embodiment, since the concave portion  1130  of the glass member  610  is disposed to be directed in the first direction (z-direction), the glass member  610  may be disposed to face the polymer layer  411  (e.g., the polymer layer  411  in  FIG. 5 ) in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 . 
     According to an embodiment, since the thickness of the glass member  610  decreases from the first flat portion  721  of the flat portions  720  to the center c of the bending portion  710 , the glass member  610  may have an inclined surface  1131  formed in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 . According to an embodiment, since the thickness of the glass member  610  decreases from the first flat portion  721  of the flat portions  720  to the center c of the bending portion  710 , the glass member  610  may have a concave portion  1130  formed in the section between the first flat portion  721  of the flat portions  720  and the center c of the bending portion  710 , and the surface of the concave portion  1130  may include the inclined surface  1131 . 
     The electronic device  100  according to certain embodiments is able to reduce the user&#39;s visibility of the boundary portion of a folding area (e.g., the folding area  130   c  in  FIG. 1 ) and reduce cracks of the glass member  610  because the glass member  610  includes the concave portion  1130 . The glass member  610  according to the embodiment shown in  FIGS. 10 to 12  is able to further reduce damage to the glass member  610 , compared to the glass member  610  according to the embodiment shown in  FIGS. 6 to 8 , because the concave portion  1130  is disposed to be directed in the first direction (z-direction). For example, as shown in  FIG. 10 , when the electronic device  100  is in the folded state, the stress  1001  due to tensile force may be concentrated in the second direction (-z-direction) from the bending portion  710 . In the embodiment shown in  FIGS. 6 to 8 , since the concave portion  1130  is formed by varying the curvature of the rear surface (e.g., the surface directed in the second direction (-z-direction)) of the glass member  610 , the rear surface of the glass member  610  in which the curvature is varied and the portion where the stress  1001  is concentrated may be close to each other, and thus the glass member  610  may be damaged. On the other hand, since the glass member  610  according to the embodiment shown in  FIGS. 10 to 12  forms the concave portion  1130  by varying the curvature of the front surface (e.g., the surface directed in the first direction (z-direction)) of the glass member  610 , the front surface of the glass member  610  in which the curvature is varied and the portion where the stress  1001  is concentrated may be spaced apart from each other, thereby reducing damage to the glass member  610 . 
       FIG. 13  is a cross-sectional view illustrating irregularities  911  formed on a glass layer  412  according to another embodiment. 
     The glass layer  412  illustrated in  FIG. 13  may be at least partially similar to the glass layer  412  shown in  FIGS. 5 to 12 , or may include other embodiments. Hereinafter, only the characteristics of the glass layer  412  that were not described in  FIGS. 5 to 12  or differ therefrom will be described with reference to  FIG. 13 . 
     Referring to  FIG. 13 , a glass member  610  according to another embodiment may be disposed such that a concave portion  1130  is directed in the first direction (z-direction), instead of the second direction (-z-direction), and a plurality of irregularities  1311  may be formed on the surface of the concave portion  1130 . For example, the plurality of irregularities  1311  may be formed regularly or irregularly by physical micro-pattern processing or chemical etching. Surface treatment may be performed on the glass member  610  according to certain embodiments so as to form a plurality of irregularities  1311  on the surface of the concave portion  1130 , thereby inducing diffused reflection of light. The electronic device  100  according to certain embodiments may further reduce the user&#39;s visibility of the boundary of a folding area (e.g., the folding area  130   c  in  FIG. 1 ) using diffused reflection of light by the plurality of irregularities  1311 . 
       FIG. 14  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to a comparative example. For example,  FIG. 14  may be a cross-sectional view showing the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     Referring to  FIG. 14 , the flexible display  400  according to a comparative example may include a display panel  430 , a polarization layer  420  disposed in the first direction (z-direction) from the display panel  430 , a shock absorption layer  1425  disposed in the first direction (z-direction) from the polarization layer  420 , a glass layer  412  (e.g., UTG) disposed in a first direction (z-direction) from the shock absorption layer  1425 , and a polymer layer  411  (e.g., PET) formed in the first direction (z-direction) from the glass layer  412 . The flexible display  400  according to the comparative example may further include a polymer member  440  disposed in a second direction (-z-direction) opposite the first direction (z-direction) from the display panel  430  and a conductive plate  450  disposed in the second direction (-z-direction) from the polymer member  440 . 
     In the flexible display  400  according to the comparative example, the polymer layer  411  and the glass layer  412  may be attached to each other by a first adhesive  1410  disposed between the polymer layer  411  and the glass layer  412 . 
     In the flexible display  400  according to the comparative example, the glass layer  412  and the shock absorption layer  1425  may be attached to each other by a second adhesive  1420  disposed between the glass layer  412  and the shock absorption layer  1425 . 
     In the flexible display  400  according to the comparative example, the shock absorption layer  1425  and the polarization layer  420  may be attached to each other by a third adhesive  1430  disposed between the shock absorption layer  1425  and the polarization layer  420 . 
     In the flexible display  400  according to the comparative example, the polarization layer  420  and the display panel  430  may be attached to each other by a fourth adhesive  1440  between the polarization layer  420  and the display panel  430 . 
     In the flexible display  400  according to the comparative example, at the edge of the flexible display  400 , an end  1415   a  (e.g., an edge portion) of the glass layer  412  may be disposed to protrude further in a side direction (x-direction) than an end  1420   a  (e.g., an edge portion) of the second adhesive  1420 . For example, the area of the glass layer  412  according to the comparative example may be greater than the area of the second adhesive  1420 , and the end  1415   a  of the glass layer  412  may be disposed to protrude further in the side direction (x-direction) than the end  1420   a  of the second adhesive  1420 . The side direction (x-direction) is a third direction (x-direction) perpendicular to the first direction (z-direction) and the second direction (-z-direction), and may be defined as a direction in which the flexible display  400  faces a side member (e.g., the first side member  113  or the second side member  123  in  FIG. 1 ) of the electronic device  100 . 
     In the flexible display  400  according to the comparative example, since the end  1415   a  of the glass layer  412  protrudes further in the side direction (x-direction) than the end  1420   a  of the second adhesive  1420 , the edge of the glass layer  412  may be easily damaged  1401  by an external force. Hereinafter, a structure of the flexible display  400  for preventing the edge of the glass layer  412  from being easily damaged  1401  by an external force will be described in detail with reference to  FIGS. 15 to 20 . For example, as will be described later with reference to  FIGS. 15 to 20 , at least one of the adhesives or components disposed in the first direction (z) or the second direction (-z) of the glass layer  412  may have an end that is formed to match the end of the glass layer  412  or to be greater than the same. 
       FIG. 15  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to an embodiment. For example,  FIG. 15  may be a cross-sectional view showing the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     The flexible display  400  shown in  FIG. 15  may be at least partially similar to the flexible display  400  shown in  FIG. 5 , or may include other embodiments. The glass layer  412  shown in  FIG. 15  may be at least partially similar to the glass layer  412  shown in  FIGS. 5 to 13 , or may include other embodiments. Hereinafter, only the characteristics of the flexible display  400  that were not described in  FIG. 5  or differ therefrom will be described with reference to  FIG. 15 . 
     Referring to  FIG. 15 , the flexible display  400  according to an embodiment may include a display panel  430 , a polarization layer  420  disposed in a first direction (z-direction) from the display panel  430 , a shock absorption layer  1425  (e.g., PET) disposed in the first direction (z-direction) from the polarization layer  420 , a glass layer  412  (e.g., UTG) disposed in the first direction (z-direction) from the shock absorption layer  1425 , and a polymer layer  411  (e.g., PET) formed in the first direction (z-direction) from the glass layer  412 . The flexible display  400  according to an embodiment may further include a polymer member  440  disposed in a second direction (-z-direction) opposite the first direction (z-direction) from the display panel  430  and a conductive plate  450  disposed in the second direction (-z-direction) from the polymer member  440 . 
     In the flexible display  400  according to an embodiment, the polymer layer  411  and the glass layer  412  may be attached to each other by a first adhesive  1410  disposed between the polymer layer  411  and the glass layer  412 . 
     In the flexible display  400  according to an embodiment, the glass layer  412  and the shock absorption layer  1425  may be attached to each other by a second adhesive  1420  disposed between the glass layer  412  and the shock absorption layer  1425 . 
     In the flexible display  400  according to an embodiment, the shock absorption layer  1425  and the polarization layer  420  may be attached to each other by a third adhesive  1430  disposed between the shock absorption layer  1425  and the polarization layer  420 . 
     In the flexible display  400  according to an embodiment, the polarization layer  420  and the display panel  430  may be attached to each other by a fourth adhesive  1440  between the polarization layer  420  and the display panel  430 . 
     According to an embodiment, each of the first adhesive  1410  to the fourth adhesive  1440  may include at least one of an OCA (optical clear adhesive), a PSA (pressure sensitive adhesive), a heat-responsive adhesive, a general adhesive, or a double-sided tape. 
     Unlike the flexible display  400  according to the comparative example shown in  FIG. 14 , in the flexible display  400  according to the embodiment shown in  FIG. 15 , the end  1415   a  (e.g., an edge portion) of the glass layer  412  may be disposed not to protrude further in a side direction (x-direction) than the end  1420   a  (e.g., an edge portion) of the second adhesive  1420 . For example, the end  1415   a  of the glass layer  412  and the end  1420   a  of the second adhesive  1420  may be disposed to form a straight line. The side direction (x-direction) is a third direction (x-direction) perpendicular to the first direction (z-direction) and the second direction (-z-direction), and may be defined as a direction in which the flexible display  400  faces a side member (e.g., the first side member  113  or the second side member  123  in  FIG. 1 ) of the electronic device  100 . 
     The area of the glass layer  412  may be substantially the same as the area of the second adhesive  1420 , and the end  1415   a  of the glass layer  412  and the end  1420   a  of the second adhesive  1420  may be disposed to form a straight line at the edge of the flexible display  400 . 
     The area of the first adhesive  1410  is greater than the area of the glass layer  412 , and the end  1410   a  of the first adhesive  1410  may be disposed to protrude further in the side direction (x-direction) than the end  1415   a  of the glass layer  412 . 
     In the flexible display  400  according to the embodiment shown in  FIG. 15 , the ends of the adhesives positioned in the first direction (z-direction) and in the second direction (-z-direction), respectively, from the glass layer  412  may protrude further than the end  1415   a  of the glass layer  412  or form a straight line, thereby preventing the edge of the glass layer  412  from being easily damaged by an external force. 
       FIG. 16  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to another embodiment. For example,  FIG. 16  may be a cross-sectional view showing the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     The flexible display  400  shown in  FIG. 16  may be at least partially similar to the flexible display  400  shown in  FIG. 15 , or may include other embodiments. The glass layer  412  shown in  FIG. 16  may be at least partially similar to the glass layer  412  shown in  FIG. 15 , or may include other embodiments. Hereinafter, only the characteristics of the flexible display  400  that were not described in  FIG. 15  or differ therefrom will be described with reference to  FIG. 16 . 
     Unlike the flexible display  400  shown in  FIG. 15 , in the flexible display  400  according to the embodiment shown in  FIG. 16 , the end  1420   a  of the second adhesive  1420  may be disposed to protrude further in the side direction (x-direction) than the end  1415   a  of the glass layer  412 . 
     The area of each of the first adhesive  1410  and the second adhesive may be greater than the area of the glass layer  412 , and the end  1410   a  of the first adhesive  1410  and the end  1420   a  of the second adhesive  1420  may be disposed to protrude further in the side direction (x-direction). 
     In the flexible display  400  according to the embodiment shown in  FIG. 16 , the ends of the adhesives positioned in the first direction (z-direction) and in the second direction (-z-direction), respectively, from the glass layer  412  may protrude further than the end  1415   a  of the glass layer  412 , thereby preventing the edge of the glass layer  412  from being easily damaged by an external force. 
       FIG. 17  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to another embodiment. For example,  FIG. 17  may be a cross-sectional view showing the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     The flexible display  400  shown in  FIG. 17  may be at least partially similar to the flexible display  400  shown in  FIGS. 15 to 16 , or may include other embodiments. The glass layer  412  shown in  FIG. 17  may be at least partially similar to the glass layer  412  shown in  FIG. 15 , or may include other embodiments. Hereinafter, only the characteristics of the flexible display  400  that were not described in  FIGS. 15 to 16  or differ therefrom will be described with reference to  FIG. 17 . 
     Unlike the flexible display  400  shown in  FIG. 15 , in the flexible display  400  according to the embodiment shown in  FIG. 17 , the end  1415   a  of the glass layer  412  and the end  1410   a  of the first adhesive  1410  may form a straight line, and the end  1420   a  of the second adhesive  1420  may be disposed to protrude further in the side direction (x-direction) than the end  1415   a  of the glass layer  412 . 
     The area of the glass layer  412  and the area of the first adhesive  1410  may be the same, and the end  1415   a  of the glass layer  412  and the end  1410   a  of the first adhesive  1410  may be disposed to form a straight line. 
     The area of the second adhesive may be greater than the area of the glass layer  412 , and the end  1420   a  of the second adhesive  1420  may be disposed to protrude further in the side direction (x-direction) than the end  1415   a  of the glass layer  412 . 
     In the flexible display  400  according to the embodiment shown in  FIG. 17 , the ends of the adhesives positioned in the first direction (z-direction) and in the second direction (-z-direction), respectively, from the glass layer  412  may protrude further than the end  1415   a  of the glass layer  412  or form a straight line, thereby preventing the edge of the glass layer  412  from being easily damaged by an external force. 
       FIG. 18  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to another embodiment. For example,  FIG. 18  may be a cross-sectional view showing the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     The flexible display  400  shown in  FIG. 18  may be at least partially similar to the flexible display  400  shown in  FIGS. 15 to 17 , or may include other embodiments. The glass layer  412  shown in  FIG. 18  may be at least partially similar to the glass layer  412  shown in  FIG. 15 , or may include other embodiments. Hereinafter, only the characteristics of the flexible display  400  that were not described in  FIGS. 15 to 17  or differ therefrom will be described with reference to  FIG. 18 . 
     Unlike the flexible display  400  shown in  FIG. 15 , in the flexible display  400  according to the embodiment shown in  FIG. 18 , an adhesive member  1810  may be further disposed in the side direction (x-direction) from the end  1420   a  of the second adhesive  1420  and the end  1415   a  of the glass layer  412 . 
     The adhesive member  1810  may be disposed in the first direction (z-direction) from the shock absorption layer  1425  at the edge of the flexible display  400 . The material of the adhesive member  1810  may include the same or similar material as the material of the first adhesive  1410  to the fourth adhesive  1440 . For example, the material of the adhesive member  1810  may include PSA or resin. 
     The adhesive member  1810  may be disposed at the edge of the flexible display  400  in the side direction (x-direction) from the end  1415   a  of the glass layer  412 , thereby performing a function of protecting the edge of the glass layer  412 . 
     The thickness of the adhesive member  1810  may be greater than the thickness of the second adhesive  1420 . 
       FIG. 19  is a cross-sectional view schematically illustrating an edge of a flexible display  400  according to another embodiment.  FIG. 20  illustrates an example of a method of peeling the glass layer  412  from the flexible display  400  shown in  FIG. 19 . For example,  FIG. 19  may be a cross-sectional view illustrating the edge of the flexible display  400  taken along the line k-k′ in  FIG. 4B . 
     The flexible display  400  shown in  FIGS. 19 and 20  may be at least partially similar to the flexible display  400  shown in  FIGS. 15 to 18 , or may include other embodiments. The glass layer  412  shown  FIGS. 19 and 20  may be at least partially similar to the glass layer  412  shown in  FIGS. 5 to 13 , or may include other embodiments. Hereinafter, only the characteristics of the flexible display  400  that were not described in  FIGS. 15 to 18  or differ therefrom will be described with reference to  FIGS. 19 and 20 . 
     Unlike the flexible display  400  shown in  FIG. 15 , in the flexible display  400  according to the embodiment shown in  FIGS. 19 and 20 , the end  1425   a  of the shock absorption layer  1425  and the end  1430   a  of the third adhesive  1430  may protrude further in the side direction (x-direction) than the end of the polarization layer  420 , the end  1440   a  of the fourth adhesive  1440 , and the end  430   a  of the display panel  430 . 
     The area of the shock absorption layer  1425  may be greater than the area of the polarization layer  420 , the area of the fourth adhesive  1440 , and the area of the display panel  430 . The end  1425   a  of the shock absorption layer  1425  may protrude further in the side direction (x-direction) than the end of the polarization layer  420 , the end  1440   a  of the fourth adhesive  1440 , and the end  430   a  of the display panel  430 . 
     The area of the shock absorption layer  1425  and the area of the third adhesive  1430  may be the same, and the end  1425   a  of the shock absorption layer  1425  and the end  1430   a  of the third adhesive  1430  may form a straight line. 
     The area of the polarization layer  420 , the area of the fourth adhesive  1440 , and the area of the display panel  430  may be the same. The end of the polarization layer  420 , the end  1440   a  of the fourth adhesive  1440 , and the end  430   a  of the display panel  430  may form a straight line. 
     The thickness d 2  of the second adhesive  1420  may be less than the thickness of each of the first adhesive  1410 , the third adhesive  1430 , and the fourth adhesive  1440 . For example, the thickness d 2  of the second adhesive  1420  may be designed to be less than the thickness d 1  of the first adhesive  1410  by 5 μm or more. The thickness d 2  of the second adhesive  1420  may be designed to be less than the thickness d 3  of the third adhesive  1430  by 5 μm or more. The thickness d 2  of the second adhesive  1420  may be designed to be less than the thickness d 4  of the fourth adhesive  1440  by 5 μm or more. The thickness d 2  of the second adhesive  1420  disposed in the second direction (-z-direction) from the glass layer  412  may be less than the thickness of each of the first adhesive  1410 , the third adhesive  1430 , and the fourth adhesive  1440 , thereby increasing the resistance of the glass layer  412  against the external force and reducing damage to the glass member (e.g., UTG, the glass member  610  in  FIG. 6 ). 
     In general, in the case of a foldable electronic device  100  including the UTG as a glass member of the glass layer  412 , when the UTG is damaged, it may be difficult to peel only the damaged glass layer  412  from the flexible display  400  because of the fragments of the UTG. The user must replace the whole of the flexible display  400  when the UTG is damaged due to the above difficulties, which may increase repair costs. 
     In the flexible display  400  according to the embodiment shown in  FIGS. 19 and 20 , since the end  1425   a  of the shock absorption layer  1425  and the end  1430   a  of the third adhesive  1430  may be disposed to protrude further in the side direction (x-direction) than the end of the polarization layer  420 , the end  1440   a  of the fourth adhesive  1440 , and the end  430   a  of the display panel  430 , it is possible to peel only some layers including the glass layer  412  from the flexible display  400  and replace the same when the glass member  610  (e.g., UTG, the glass member  610  in  FIG. 6 ) is damaged. 
     The flexible display  400  according to the embodiment shown in  FIGS. 19 and 20  may be designed such that the high-temperature adhesion of the third adhesive  1430  disposed in the second direction (-z-direction) from the shock absorption layer  1425  is relatively low in order to facilitate peeling only some layers including the glass layer  412  from the flexible display  400  and replacing the same. For example, the high-temperature adhesion of the third adhesive  1430  may be lower than the high-temperature adhesion of each of the first adhesive  1410 , the second adhesive  1420 , and the fourth adhesive  1440 . 
     The adhesion of each of the first adhesive  1410 , the second adhesive  1420 , and the fourth adhesive  1440  may be 450 gf/in or more at room temperature. 
     The adhesion of each of the first adhesive  1410 , the second adhesive  1420 , and the fourth adhesive  1440  may be greater than 150 gf/in at a high temperature. The high temperature may be defined as, for example, a temperature of about 70 degrees to about 80 degrees. 
     The adhesion of the third adhesive  1430  may be 450 gf/in or more at room temperature. 
     The adhesion of the third adhesive  1430  may be less than or equal to 150 gf/in at a high temperature. 
     The third adhesive  1430  may react to UV (ultraviolet ray) light or laser in a specified wavelength band to be reduced in the adhesion thereof compared to each of the first adhesive  1410 , the second adhesive  1420 , and the fourth adhesive  1440 . 
     The third adhesive  1430  may include a photoinitiator component that reacts to UV light or laser. 
     The electronic device according to certain embodiments of the disclosure is able to protect glass from an external impact and reduce a phenomenon in which a curved surface of the flexible display is observed with the naked eye in the folded portion of the flexible display, which is positioned at the boundary between the first housing and the second housing. 
     In addition to this, various effects that are directly or indirectly recognized through the disclosure may be provided. 
     According to certain embodiments, an electronic device comprises a first housing; a second housing; a hinge disposed between the first housing and the second housing such that the second housing is foldable at one end of the first housing; and a flexible display disposed on a surface of the first housing and a surface of the second housing, wherein the flexible display comprises a display panel, and a glass layer disposed on the display panel, such that the display panel is between the glass layer and the surface of the first housing and the surface of the second housing, wherein the glass layer comprises: a bendable portion configured to be flat in an unfolded state when the first housing and the second housing are disposed horizontally adjacent, and to be bent in a folded state when the first housing and the second housing are vertically adjacent; and a first flat portion adjacent to the bending portion to form a boundary and a second flat portion disposed to extend from the first flat portion to an edge of the glass layer, wherein the glass layer comprises a glass member, wherein the glass member has a first thickness in the second flat portion, has a second thickness at the center of the bending portion, and has a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion and the center of the bending portion, and wherein the thickness of the glass member gradually decreases from the first flat portion to the center of the bending portion forming a concave portion. 
     According to certain embodiments, the glass member includes ultra-thin glass (UTG), and wherein a width of the concave portion is greater than a width of the bending portion. 
     According to certain embodiments, the surface of the concave portion has an inclined surface, and wherein when the angle of the inclined surface with respect to the surface of the second flat portion is defined as θ, and wherein tan θ is less than or equal to 1/10. 
     According to certain embodiments, regular irregularities are formed on the inclined surface of the concave portion. 
     According to certain embodiments, irregular irregularities are formed on the inclined surface of the concave portion. 
     According to certain embodiments, the first thickness is at least double the second thickness. 
     According to certain embodiments, the concave portion is formed in the first direction from the glass layer. 
     According to certain embodiments, the concave portion is formed in a second direction opposite the first direction from the glass layer. 
     According to certain embodiments, the adhesive member is formed in the third direction from the end of the glass layer so as to correspond between the first adhesive and the shock absorption layer. 
     According to certain embodiments, the area of the shock absorption layer is greater than the area of the display panel, wherein the area of a third adhesive disposed between the shock absorption layer and the display panel is greater than the area of the display, and wherein at at least one edge of the flexible display, an end of the shock absorption layer and an end of the third adhesive protrude from an end of the display panel in a third direction perpendicular to the first direction. 
     According to certain embodiments, the high-temperature adhesion of the third adhesive is less than the high-temperature adhesion of each of the first adhesive and the second adhesive. 
     According to certain embodiments, the third adhesive comprises a photoinitiator component to react to UV (ultraviolet ray) light or laser in a specified wavelength band, thereby lowering the adhesion. 
     According to certain embodiments, a thickness of the second adhesive is less than a thickness of the first adhesive. 
     According to certain embodiments, the flexible display further comprises: a polarization layer disposed between the display panel and the glass layer; a shock absorption layer disposed between the polarization layer and the glass layer; and a polymer layer disposed in the first direction from the glass layer, wherein the area of a first adhesive disposed between the glass layer and the polymer layer is greater than or equal to the area of the glass layer, and wherein the area of a second adhesive disposed between the glass layer and the shock absorption layer is greater than or equal to the area of the glass layer. 
     According to certain embodiments, the area of the first adhesive disposed between the glass layer and the polymer layer is greater than the area of the glass layer, wherein the area of the second adhesive disposed between the glass layer and the shock absorption layer is equal to the area of the glass layer, and wherein at at least one edge of the flexible display, an end of the first adhesive protrudes from an end of the glass layer in a third direction perpendicular to the first direction, and an end of the second adhesive and the end of the glass layer are disposed to form a straight line. 
     According to certain embodiments, the area of the first adhesive disposed between the glass layer and the polymer layer is greater than the area of the glass layer, wherein the area of the second adhesive disposed between the glass layer and the shock absorption layer is greater than the area of the glass layer, and wherein at at least one edge of the flexible display, an end of the first adhesive protrudes from an end of the glass layer in a third direction perpendicular to the first direction, and an end of the second adhesive protrudes in the third direction from the end of the glass layer. 
     According to certain embodiments, the area of the first adhesive disposed between the glass layer and the polymer layer is the same as the area of the glass layer, wherein the area of the second adhesive disposed between the glass layer and the shock absorption layer is greater than the area of the glass layer, and wherein at at least one edge of the flexible display, an end of the first adhesive and an end of the glass layer are disposed to form a straight line, and an end of the second adhesive protrudes from the end of the glass layer in a third direction perpendicular to the first direction. 
     According to certain embodiments, a glass layer for a flexible display of a foldable electronic device, the glass comprises: a bending portion configured to be bent in a folded state of the foldable electronic device; and a first flat portion adjacent to the bending portion to form a boundary and a second flat portion disposed to extend from the first flat portion to an edge of the glass layer, a glass member, wherein the glass member has a first thickness in the second flat portion, has a second thickness at the center of the bending portion, and has a third thickness less than the first thickness and greater than the second thickness in a section between the first flat portion and the center of the bending portion, and wherein the thickness of the glass member gradually decreases from the first flat portion to the center of the bending portion to form a concave portion. 
     According to certain embodiments, glass member comprises UTG (ultra-thin glass), and wherein a width of the concave portion is greater than a width of the bending portion. 
     According to certain embodiments, an inclined surface is formed on the surface of the concave portion, and wherein when the angle of the inclined surface with respect to the surface of the second flat portion is defined as θ, and tan θ is less than or equal to 1/10. 
     The embodiments disclosed herein are proposed for description and understanding of the disclosed technology and does not limit the scope of the disclosure. Accordingly, the scope of the disclosure should be interpreted as including all changes or various embodiments based on the technical spirit of the disclosure.