Patent Publication Number: US-2022221914-A1

Title: Foldable flexible display device and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a Continuation of International Application No. PCT/KR2021/017544, filed on Nov. 25, 2021, which claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0004474, filed on Jan. 13, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     The disclosure relates to display devices, and, more particular, to a foldable flexible display device. 
     2. Description of Related Art 
     A portable electronic device such as a smartphone may provide various functions, such as a call function, video playback, and Internet access and search, etc. based on various types of applications. Users often prefer to use the above-described various functions on larger displays. However, as the size of the screen is increased, portability of the electronic device may deteriorate. Accordingly, a screen size can be increased without hampering portability by using a foldable structure for the display. 
     SUMMARY 
     A foldable electronic device may include a display, housings, and hinges. The display may be foldable along an axis thereof. The housings may surround a periphery of the display, and an electronic component for driving the display may be disposed within the housings. The hinges may be arranged between the housings to support a first sub-housing and a second sub-housing, rotatable relative to one another, to support configurations of the display, such as being unfolded to 180 degrees to form a plane, or folded to 0 (zero) degrees to close the flexible display. 
     According to an embodiment of the disclosure, in a foldable electronic device equipped with a flexible display, a tactile sense of detent may be implemented in mounting portions, and a free stop may be implemented in both flat sections using cam structures that engage with each other within a hinge structure. However, when the free stop is implemented, and two flat surfaces within a central section of the cam are engaged, a reaction force of the flexible display gradually increases, which may render it more difficult to implement the free stop. 
     Therefore, an aspect of the disclosure provides a foldable flexible display device and an electronic device capable of variable configurations that are stable fixed, by variously setting an angle between a first housing and a second housing. 
     Additional aspects of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure. 
     In accordance with an aspect of the disclosure, an electronic device is disclosed, including: a flexible display including a first region and a second region, a first housing supporting the first region, a second housing supporting the second region, and a hinge structure connecting the first housing to the second housing, wherein the hinge structure includes: an axis shaft forming a rotational axis, a sliding cam slidably coupled to the axis shaft, and including a first sliding cam in which a first sliding cam nose is formed, a second sliding cam in which a second sliding cam nose is formed, a third sliding cam in which a third sliding cam nose is formed, and a fourth sliding cam in which a fourth sliding cam nose is formed, a cam body including a first rotation cam including a first rotation cam nose engaged with the first sliding cam, a second rotation cam including a second rotation cam nose engaged with the second sliding cam and a third rotation cam nose engaged with the third sliding, and a third rotation cam including a fourth rotation cam nose engaged with the fourth sliding cam, and elastic members including a first elastic member disposed between the first sliding cam and the second sliding cam, and a second elastic member disposed between the third sliding cam and the fourth sliding cam, wherein the first rotation cam nose, the second rotation cam nose, the third rotation cam nose, and the fourth rotation cam nose are disposed on different imaginary lines extending parallel to the rotational axis of the axis shaft. 
     The first sliding cam nose, the second sliding cam nose, the third sliding cam nose, and the fourth sliding cam nose may be disposed on a same imaginary line. 
     The first elastic member may apply an elastic force to the first sliding cam and the second sliding cam, along a direction in which the first sliding cam is movable away from the second sliding cam, and the second elastic member may apply an elastic force to the third sliding cam and the fourth sliding cam, along a direction in which the third sliding cam is movable away from the fourth sliding cam. 
     The cam body may be rotatable together with the axis shaft. 
     When the first housing and the second housing are disposed at a first angle relative to one another, the first rotation cam may be configured to receive a rotational force in a first direction by the first elastic member and the first sliding cam, and the third rotation cam may be configured to receive a rotational force in a second direction opposite to the first direction by the second elastic member and the third sliding cam. 
     When the first housing and the second housing are disposed at a second angle relative to one another, the second rotation cam may be configured to receive a rotational force in the second direction by the first elastic member and the second sliding cam, and the third rotation cam may be configured to receive a rotational force in the first direction by the second elastic member and the third sliding cam. 
     When the first housing and the second housing are disposed at a third angle relative to one another, the second rotation cam may be configured to receive a rotational force in the first direction by the first elastic member and the second sliding cam, and the fourth rotation cam may be configured to receive a rotational force in the second direction by the second elastic member and the fourth sliding cam. 
     The first angle may be greater than the second angle, and the second angle may be greater than the third angle. 
     When the first housing and the second housing may be rotated to an angle between the first angle and the second angle, the first sliding cam, the second sliding cam, and the first elastic member may be moved along a direction in which the axis shaft extends. 
     When the first housing and the second housing may be rotated to an angle between the second angle and the third angle, the third sliding cam, the fourth sliding cam, and the second elastic member may be moved along a direction in which the axis shaft extends. 
     When the first housing and the second housing may be disposed in an unfolded configuration, the first rotation cam nose may be supported on the first sliding cam nose by the first elastic member, in a direction along which the first housing and the second housing unfold relative to one another. 
     When the first housing and the second housing may be disposed in an folded configuration, the fourth rotation cam nose may be supported on the fourth sliding cam nose by the second elastic member, in a direction along which the first housing and the second housing fold together. 
     In accordance with another aspect of the disclosure, a foldable flexible display device is disclosed, including: a first housing, a second housing, a flexible display disposed on the first housing and the second housing, and a hinge structure provided to rotatably couple the first housing to the second housing, wherein the hinge structure includes: an axis shaft forming a rotational axis, a sliding cam slidably coupled to the axis shaft, and including a first sliding cam in which a first sliding cam nose is formed, a second sliding cam in which a second sliding cam nose is formed, a third sliding cam in which a third sliding cam nose is formed, and a fourth sliding cam in which a fourth sliding cam nose is formed, a cam body including a first rotation cam engaged with the first sliding cam and including a first rotation cam nose, a second rotation cam engaged with the second sliding cam and the third sliding cam, and including a second rotation cam nose and a third rotation cam nose, and a third rotation cam engaged with the fourth sliding cam and including a fourth rotation cam nose, wherein the first sliding cam nose, the second sliding cam nose, the third sliding cam nose, and the fourth sliding cam nose are disposed on a same imaginary line, and wherein the first rotation cam nose, the second rotation cam nose, the third rotation cam nose, and the fourth rotation cam nose are disposed on different imaginary lines extending parallel to the rotational axis of the axis shaft. 
     When an angle between the first housing and the second housing may be a first angle, the first rotation cam may be supported in a first direction by the first sliding cam, and the third rotation cam may be supported in a second direction opposite to the first direction by the third sliding cam. 
     When an angle between the first housing and the second housing may be a second angle, the second rotation cam may be supported in the second direction by the second sliding cam, and the third rotation cam may be supported in the first direction by the third sliding cam. 
     When an angle between the first housing and the second housing a third angle, the second rotation cam may be supported in the first direction by the second sliding cam, and the fourth rotation cam may be supported in the second direction by the fourth sliding cam. 
     The hinge structure may include a first elastic member disposed between the first sliding cam and the second sliding cam, and a second elastic member disposed between the third sliding cam and the fourth sliding cam. 
     When the first housing and the second housing may be disposed in an unfolded configuration, the first rotation cam may be supported by the first sliding cam, along a direction in which the first housing and the second housing unfold relative to one another. 
     When the first housing and the second housing may be disposed in a folded configuration, the fourth rotation cam may be supported by the fourth sliding cam, along a direction, in which the first housing and the second housing fold together. 
     The second rotation cam nose may be formed on a first surface of the second rotation cam facing the second sliding cam, and the third rotation cam nose may be formed on a second surface of the second rotation cam opposite to the first surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a view illustrating an unfolded state of an electronic device according to certain embodiments of the disclosure; 
         FIG. 2  is a view illustrating a folded state of the electronic device according to certain embodiments of the disclosure; 
         FIG. 3  is an exploded perspective view of the electronic device according to certain embodiments of the disclosure; 
         FIG. 4  is a view illustrating a front surface of a hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 5  is a view illustrating a rear surface of the hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 6  is a view illustrating an example of an exploded perspective view of some components of the hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 7  is a rear view illustrating an unfolded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 8  is an enlarged view of part A shown in  FIG. 7 ; 
         FIG. 9  is a side view illustrating the unfolded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 10  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a first angle according to certain embodiments of the disclosure; 
         FIG. 11  is an enlarged view of part B shown in  FIG. 10 ; 
         FIG. 12  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the first angle according to certain embodiments of the disclosure; 
         FIG. 13  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a second angle according to certain embodiments of the disclosure; 
         FIG. 14  is an enlarged view of part C shown in  FIG. 13 ; 
         FIG. 15  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the second angle according to certain embodiments of the disclosure; 
         FIG. 16  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a third angle according to certain embodiments of the disclosure; 
         FIG. 17  is an enlarged view of part D shown in  FIG. 16 ; 
         FIG. 18  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the third angle according to certain embodiments of the disclosure; 
         FIG. 19  is a rear view illustrating a folded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure; 
         FIG. 20  is an enlarged view of part E shown in  FIG. 19 ; and 
         FIG. 21  is a side view illustrating the folded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The electronic device according to certain embodiments disclosed in the disclosure may have various types of devices. For example, the electronic device may include a portable communication device (e.g., a smart phone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or a home appliance device. The electronic device according to the embodiment of the disclosure is not limited to the above-described devices. 
     The certain embodiments and the terms used therein are not intended to limit the technology disclosed herein to specific forms, and the disclosure should be understood to include various modifications, equivalents, and/or alternatives to the corresponding embodiments. In describing the drawings, similar reference numerals may be used to designate similar constituent elements. A singular expression may include a plural expression unless they are definitely different in a context. The expressions “A or B,” “at least one of A or/and B,” or “one or more of A or/and B,” and the like used herein may include any and all combinations of one or more of the associated listed items. Herein, the expressions “a first”, “a second”, “the first”, “the second”, etc., may simply be used to distinguish an element from other elements, but is not limited to another aspect (importance or order) of elements. When an element (e.g., a first element) is referred to as being “(functionally or communicatively) coupled,” or “connected” to another element (e.g., a second element), the first element may be connected to the second element, directly (e.g., wired), wirelessly, or through a third component. 
     As used herein, the term “module” may refer to a unit that includes one or a combination of two or more of hardware, software, or firmware. A “module” may be interchangeably used with terms such as, for example, unit, logic, logical block, component, or circuit. The module may be a minimum unit or part of an integrated component. The module may be a minimum unit or part of performing one or more functions. The “module” can be implemented mechanically or electronically. For example, a “module” may be implemented in the form of an application-specific integrated circuit (ASIC). 
     Certain embodiments of the present document may be implemented as software (e.g., a program) including one or more instructions stored in a storage medium (e.g., an internal memory or an external memory) readable by a machine (e.g., the electronic device  101 ). For example, a processor (not shown) of a device (e.g., the electronic device  101 ) may call at least one instruction among one or more instructions stored in a storage medium and execute the instruction. This makes it possible for the device to be operated to perform at least one function according to the called at least one instruction. The one or more instructions may include code generated by a compiler or code executable by an interpreter. Storage medium readable by machine, may be provided in the form of a non-transitory storage medium. “Non-transitory” means that the storage medium is a tangible device and does not contain a signal (e.g., electromagnetic wave), and this term includes a case in which data is semi-permanently stored in a storage medium and a case in which data is temporarily stored in a storage medium. 
     The method according to the various disclosed embodiments may be provided by being included in a computer program product. Computer program products may be traded between sellers and buyers as commodities. Computer program products are distributed in the form of a device-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or are distributed directly or online (e.g., downloaded or uploaded) between two user devices (e.g., smartphones) through an application store (e.g., PlayStore™). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or created temporarily in a device-readable storage medium such as the manufacturer&#39;s server, the application store&#39;s server, or the relay server&#39;s memory. 
     According to certain embodiments, each component (e.g., a module or a program) of the above-described components may include a singular or a plurality of entities, and some of the plurality of entities may be separately arranged in other components. According to certain embodiments, one or more components or operations among the above-described corresponding components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., a module or a program) may be integrated into one component. In this case, the integrated component may perform one or more functions of each component of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. Operations performed by a module, a program module, or other elements according to certain embodiments of the disclosure may be executed sequentially, in parallel, repeatedly, or in a heuristic method. Also, a portion of operations may be executed in different sequences, omitted, or other operations may be added. 
       FIG. 1  is a view illustrating an unfolded state of an electronic device according to certain embodiments of the disclosure.  FIG. 2  is a view illustrating a folded state of the electronic device according to certain embodiments of the disclosure. 
     Referring to  FIGS. 1 and 2 , according to an embodiment, an electronic device  101  may include a foldable housing  300 , a hinge cover (e.g., a hinge cover  330  of  FIG. 2 ) provided to cover a foldable portion of the foldable housing  300 , and a flexible or foldable display  200  (hereinafter referred to as “display”  200 ) arranged in a space formed by the foldable housing  300 . According to an embodiment, a surface on which the display  200  is arranged is defined as a front surface of the electronic device  101 . In addition, an opposite surface of the front surface is defined as a rear surface of the electronic device  101 . In addition, a surface surrounding a space between the front surface and the rear surface is defined as a side surface of the electronic device  101 . 
     According to certain embodiments, the foldable housing  300  may include a first housing structure  310 , a second housing structure  320  including a sensor region  324 , a first rear cover  380 , a second rear cover  390 , and a hinge structure (e.g., a hinge structure  500  of  FIG. 3 ). The foldable housing  300  of the electronic device  101  is not limited to the shape and coupling shown in  FIGS. 1 and 2 , and may be implemented by other shapes or other combination and/or coupling of components. For example, in another embodiment, the first housing structure  310  and the first rear cover  380  may be integrally formed, and the second housing structure  320  and the second rear cover  390  may be integrally formed. 
     According to certain embodiments, the first housing structure  310  may be connected to the hinge structure (e.g., the hinge structure  500  of  FIG. 3 ), and include a first surface facing a first direction, and a second surface facing a second direction opposite the first direction. The second housing structure  320  may be connected to the hinge structure  500  and include a third surface facing a third direction and a fourth surface facing a fourth direction opposite to the third direction. The second housing structure  320  may be rotatable relative to the first housing structure  310  about the hinge structure  500 . Accordingly, the electronic device  101  may be variable in form, and include both folded and unfolded configurations (e.g., folded and unfolded “state”). The first surface of the electronic device  101  may be disposed to face the third surface in the folded state of the electronic device  101 , and the third direction may be the same as the first direction in the unfolded state of the electronic device  101 . 
     According to certain embodiments, the first housing structure  310  and the second housing structure  320  may be arranged on opposite sides about a folding axis (A-axis), and may have an overall symmetrical shape with respect to the folding axis A. As will be described later, an angle or a distance between the first housing structure  310  and the second housing structure  320  may vary depending on whether the electronic device  101  is in the folded state, or the unfolded state, or an intermediate state that is partially unfolded. According to an embodiment, the second housing structure  320  further includes a sensor region  324  in which various sensors are arranged, unlike the first housing structure  310 , but in other region, the second housing structure  320  may have a shape symmetrical to the first housing structure  310 . 
     According to certain embodiments, as shown in  FIG. 1 , the first housing structure  310  and the second housing structure  320  may together form a recess for accommodating the display  200 . According to an embodiment, because of the sensor region  324 , the recess may have at least two different widths set in a direction perpendicular to the folding axis A. 
     According to an embodiment, the recess may define a first width w 1  between a first portion  310   a , which is parallel to the folding axis A of the first housing structure  310 , and a first portion  320   a  formed at a periphery of the sensor region  324  of the second housing structure  320 . The recess may define a second width w 2  between a second portion  310   b  of the first housing structure  310  and a second portion  320   b  of the second housing structure  320  that does not correspond to the sensor region  324  and is parallel to the folding axis A. In this case, the second width w 2  may be formed to be greater than the first width w 1 . As another example, the first portion  310   a  of the first housing structure  310  and the first portion  320   a  of the second housing structure  320  having an asymmetrical shape may have the first width w 1  of the recess. The second portion  310   b  of the first housing structure  310  and the second portion  320   b  of the second housing structure  320  having a symmetrical shape may have the second width w 2  of the recess. According to an embodiment, a distance from the folding axis A to the first portion  320   a  may be different from a distance from the folding axis A the second portion  320   b  of the second housing structure  320 . The width of the recess is not limited to the illustrated example. In another embodiment, the recess may have a plurality of widths due to the shape of the sensor region  324  or due to a portion, which has the asymmetric shape, of the first housing structure  310  and the second housing structure  320 . 
     According to certain embodiments, at least a portion of the first housing structure  310  and the second housing structure  320  may be formed of a metallic material or a non-metallic material having a rigidity sufficient to support the display  200 . The at least a portion formed of the metal material may provide a ground plane of the electronic device  101  and be electrically connected to a ground line formed on a printed circuit board (e.g., a printed circuit board  520  of  FIG. 3 ). 
     According to certain embodiments, the sensor region  324  may be formed to have a predetermined region adjacent to one corner of the second housing structure  320 . However, an arrangement, shape, and size of the sensor region  324  are not limited to the illustrated example. For example, in another embodiment, the sensor region  324  may be provided at another corner of the second housing structure  320  or provided at any region between an upper corner and a lower corner. In an embodiment, components for performing various functions and embedded in the electronic device  101  may be exposed on the front surface of the device  101  through the sensor region  324  or through one or more openings provided in the sensor region  324 . In certain embodiments, the components may include various types of sensors. The sensor may include at least one of a front camera, a receiver, or a proximity sensor. 
     According to certain embodiments, the first rear cover  380  may be arranged on one side of the folding axis on the rear surface of the electronic device  101 . For example, the first rear cover  380  may include a substantially rectangular periphery, and the periphery may be surrounded by the housing structure  310 . Similarly, the second rear cover  390  may be arranged on the other side of the folding axis on the rear surface of the electronic device  101 , and a periphery thereof may be surrounded by the second housing structure  320 . 
     According to certain embodiments, the first rear cover  380  and the second rear cover  390  may have a substantially symmetrical shape with respect to the folding axis (A-axis). However, the first rear cover  380  and the second rear cover  390  do are not absolutely required to have symmetrical shapes, and in another embodiment, the electronic device  101  may include the first rear cover  380  and the second rear cover  390  formed in other various shapes. In another embodiment, the first rear cover  380  may be integrally formed with the first housing structure  310 , and the second rear cover  390  may be integrally formed with the second housing structure  320 . 
     According to certain embodiments, the first rear cover  380 , the second rear cover  390 , the first housing structure  310 , and the second housing structure  320  may form a space in which various components (e.g., a printed circuit board, or a battery) may be disposed. According to an embodiment, one or more components may be arranged or visually exposed on the rear surface of the electronic device  101 . For example, at least a portion of a sub-display may be visually exposed through a first rear region  382  of the first rear cover  380 . In another embodiment, one or more components or sensors may be visually exposed through a second rear region  392  of the second rear cover  390 . In certain embodiments, the sensor may include a proximity sensor and/or a rear camera. 
     According to certain embodiments, the front camera, which is exposed on the front surface of the electronic device  101  through one or more openings provided in the sensor region  324 , or the rear camera, which is exposed through the second rear region  392  of the second rear cover  390  may include one or more lenses, an image sensor, and/or an image signal processor. A flash  313  may include a light emitting diode or a xenon lamp. In some embodiments, two or more lenses (infrared cameras, wide angle and telephoto lenses) and image sensors may be arranged on one side of the electronic device  101 . 
     Referring to  FIG. 2 , the hinge cover  330  may be arranged between the first housing structure  310  and the second housing structure  320  to cover internal components (e.g., the hinge structure  500  of  FIG. 3 ). According to an embodiment, the hinge cover  330  may be covered by a portion of the first housing structure  310  and the second housing structure  320  or exposed to the outside according to the state of the electronic device  101 , such as the unfolded state (or flat state), the intermediate state and the folded state. 
     According to an embodiment, as shown in  FIG. 1 , when the electronic device  101  is configured in the unfolded state, the hinge cover  330  may be covered by the first housing structure  310  and the second housing structure  320  so as not to be exposed. As another example, as shown in  FIG. 2 , when the electronic device  101  is configured in the folded state (e.g., a fully folded state), the hinge cover  330  may be exposed to the outside through between the first housing structure  310  and the second housing structure  320 . As another example, in response to the intermediate state in which the first housing structure  310  and the second housing structure  320  are folded to a certain angle between 0 degrees and 180 degrees, the hinge cover  330  may be partially exposed to the outside through between the first housing structure  310  and the second housing structure  320 . However, in this case, the exposed region may be less than that of the fully folded state. In an embodiment, the hinge cover  330  may include a curved surface. 
     According to certain embodiments, the display  200  may be arranged in a space formed by the foldable housing  300 . For example, the display  200  is seated on the recess formed by the foldable housing  300  and may form most of the front surface of the electronic device  101 . Accordingly, the front surface of the electronic device  101  may include the display  200 , and a partial region of the first housing structure  310  and a partial region of the second housing structure  320  adjacent to the display  200 . In addition, the rear surface of the electronic device  101  may include the first rear cover  380 , a partial region of the first housing structure  310  adjacent to the first rear cover  380 , the second rear cover  390 , and a partial region of the second housing structure  320  adjacent to the second rear cover  390 . 
     According to certain embodiments, the display  200  may include at least a region that is deformed into a flat surface or a curved surface. According to an embodiment, the display  200  may include a folding region  203 , a first region  201  arranged on one side (e.g., the left side of the folding region  203  shown in  FIG. 1 ) with respect to the folding region  203 , and a second region  202  arranged on the other side (e.g., the right side of the folding region  203  shown in  FIG. 1 ) with respect to the folding region  203 . 
     However, the division of the region of the display  200  shown in  FIG. 1  is shown merely as an example, and the display  200  may be divided into a plurality (e.g., two or four or more) regions according to a structure or function. For example, in the embodiment illustrated in  FIG. 1 , the region of the display  200  may be divided by the folding region  203  extending parallel to y-axis or the folding axis (A-axis), but in another embodiment, the display region  200  may be divided based on another folding region (e.g., a folding region parallel to x-axis) or another folding axis (e.g., a folding axis parallel to x-axis). According to an embodiment, the display  200  may be coupled to or arranged adjacent to a touch sensing circuit, a pressure sensor may be configured to measure an intensity (pressure) of a touch, and/or a digitizer may also be provided to detect a magnetic field type stylus pen. 
     According to certain embodiments, the first region  201  and the second region  202  may have an overall symmetrical shape with respect to the folding region  203 . However, the second region  202  may include a notch that is cut according to the presence of the sensor region  324 , unlike the first region  201 , but in other regions, the second region  202  may have a shape symmetrical with the first region  201 . In other words, the first region  201  and the second region  202  may include a portion having a shape symmetrical to each other and a portion having a shape asymmetrical to each other. 
     Hereinafter operations of the first housing structure  310  and the second housing structure  320  and each region of the display  200  according to the state (e.g., the folded state, the unfolded state, or the intermediate state) of the electronic device  101  will be described. 
     According to certain embodiments, when the electronic device  101  is set in the unfolded state (e.g.,  FIG. 1 ), the first housing structure  310  and the second housing structure  320  may form an angle of 180 degrees and be arranged to face a same direction. A surface of the first region  201  and a surface of the second region  202  of the display  200  may form 180 degrees and may face the same direction (e.g., the front direction of the electronic device). The folding region  203  may form the same plane as the first region  201  and the second region  202 . 
     According to certain embodiments, when the electronic device  101  is set in the folded state of the electronic device  101  (e.g.,  FIG. 2 ), the first housing structure  310  and the second housing structure  320  may be arranged to face each other. The surface of the first region  201  and the surface of the second region  202  of the display  200  may face each other while forming a relatively small angle (e.g., between 0 and 10 degrees). The folding region  203  may be formed of a curved surface having a predetermined curvature in at least a portion thereof. 
     According to certain embodiments, when the electronic device  101  is set in the intermediate state (or folded state) of the electronic device  101 , the first housing structure  310  and the second housing structure  320  may be arranged at a certain interim angle between 180 degrees and 0 degrees. The surface of the first region  201  and the surface of the second region  202  of the display  200  may form an angle greater than that in the folded state and less than that in the unfolded state. The folding region  203  may be formed of a curved surface having a predetermined curvature in at least a portion thereof, and the curvature in this case may be less than that in the folded state. 
       FIG. 3  is an exploded perspective view of the electronic device according to certain embodiments of the disclosure. 
     Referring to  FIG. 3 , in certain embodiments, the electronic device  101  may include the foldable housing  300 , the display  200 , and a substrate portion  520 . The foldable housing may include the first housing structure  310 , the second housing structure  320 , a bracket assembly  400 , the first rear cover  380 , the second rear cover  390 , and the hinge structure  500 . 
     According to certain embodiments, the display  200  may include a display panel (e.g., a flexible display panel) and one or more plates or layers (e.g., a support plate  240 ) on which the display panel is mounted. In an embodiment, the support plate  240  may be arranged between the display panel and the bracket assembly  400 . An adhesive structure (not shown) may be positioned between the support plate  240  and the bracket assembly  400  to bond the support plate  240  and the bracket assembly  400 . 
     According to certain embodiments, the bracket assembly  400  may include a first support plate  410  and a second support plate  420 . The hinge structure  500  may be arranged between the first support plate  410  and the second support plate  420 , and the hinge cover  330  that is provided to cover the hinge structure  500  when the hinge structure  500  is viewed from the outside may be disposed between the first support plate  410  and the second support plate  420 . As another example, a printed circuit board (e.g., a flexible printed circuit board (FPC)) may be arranged to cross the first support plate  410  and the second support plate  420 . 
     According to certain embodiments, the substrate unit  520  may include a first main circuit board  521  arranged on the first support plate  410  side and a second main circuit board  522  arranged on the second support plate  420  side. The first main circuit board  521  and the second main circuit board  522  may be arranged inside a space formed by the bracket assembly  400 , the first housing structure  310 , the second housing structure  320 , the first rear cover  380  and the second rear cover  390 . Components for implementing various functions of the electronic device  101  may be mounted on the first main circuit board  521  and the second main circuit board  522 . 
     According to certain embodiments, the first housing structure  310  and the second housing structure  320  may be coupled to opposite sides of the bracket assembly  400  in response to coupling the display  200  to the bracket assembly  400 . For example, the first housing structure  310  and the second housing structure  320  may slide from opposite sides of the bracket assembly  400  so as to be coupled to the bracket assembly  400 . 
     According to an embodiment, the first housing structure  310  may include a first surface  311 , and a second surface  312  facing in a direction opposite to the first surface  311 , and the second housing structure  320  may include a third surface  321 , and a fourth surface  322  facing in a direction opposite to the third surface  321 . 
     According to an embodiment, the first housing structure  310  may include a first rotation support surface  313 , and the second housing structure  320  may include a second rotation support surface  323  corresponding to the first rotation support surface  313 . The first rotation support surface  313  and the second rotation support surface  323  may include a curved surface corresponding to the curved surface included in the hinge cover  330 . 
     According to an embodiment, in response to the unfolded state of the electronic device  101  (e.g., the electronic device of  FIG. 1 ), the first rotation support surface  313  and the second rotation support surface  323  may cover the hinge cover  330  to prevent the hinge cover  330  from being exposed to the rear surface of the electronic device  101  or to allow the hinge cover  330  to be minimally exposed. As another example, in response to the folded state of the electronic device  101  (e.g., the electronic device of  FIG. 2 ), the first rotation support surface  313  and the second rotation support surface  323  may be rotated along the curved surface included in the hinge cover  330  so as to allow the hinge cover  330  to be maximally exposed to the rear surface of the electronic device  101 . 
       FIG. 4  is a view illustrating a front surface of a hinge structure provided in the electronic device according to certain embodiments of the disclosure.  FIG. 5  is a view illustrating a rear surface of the hinge structure provided in the electronic device according to certain embodiments of the disclosure.  FIG. 6  is a view illustrating an example of an exploded perspective view of some components of the hinge structure provided in the electronic device according to certain embodiments of the disclosure. 
     Referring to  FIGS. 4 to 6 , the electronic device  101  may include the hinge structure  500  which operably connects the first housing  310  to the second housing  320 . 
     The hinge structure  500  may include axis shafts  511  and  561 . The axis shafts  511  and  561  may include a first axis shaft  511  and a second axis shaft  561 . The first axis shaft  511  may form a rotation axis of the first housing  310 . The second axis shaft  561  may form a rotation axis of the second housing  320 . 
     The hinge structure  500  may include a first housing coupling portion  514  coupled to the first housing  310  and a second housing coupling portion  564  coupled to the second housing  320 . The first housing  310  may be coupled to the first housing coupling portion  514 . Accordingly, the first housing  310  may be rotatable with respect to the rotation axis formed by the first axis shaft  511 . The second housing  320  may be coupled to the second housing coupling portion  564 . Accordingly, the second housing  320  may be rotatable with respect to the rotation axis formed by the second axis shaft  561 . 
     The first housing coupling portion  514  may include a first coupling portion guide  515 . The first coupling portion guide  515  may have a substantially semicircular shape. The second housing coupling portion  564  may include a second coupling portion guide  565 . The second coupling portion guide  565  may have a substantially semicircular shape. 
     The hinge structure  500  may include a hinge body  512  coupled to the first axis shaft  511  and the second axis shaft  561 . The hinge body  512  may include a first body guide  513   a  coupled to the first coupling portion guide  515  to guide movement of the first coupling portion guide  515 , and a second body guide  513   b  coupled to the second coupling portion guide  565  to guide movement of the second coupling portion guide  565 . 
     The hinge structure  500  may include shaft gears  516  and  566  linking the first axis shaft  511  and the second axis shaft  561 . The shaft gears  516  and  566  may connect the first axis shaft  511  to the second axis shaft  561 , and thus, when the first axis shaft  511  is rotated in a first direction, the second axis shaft  561  may be rotated in a second direction opposite to the first direction. The first axis shaft  511  may be connected to the first shaft gear  516 , and the second axis shaft  561  may be connected to the second shaft gear  566 .  FIG. 6  illustrates that two first shaft gears  516  and two second shaft gears  566  are provided on opposite sides of the hinge body  512 , respectively, but if the first axis shaft  511  and the second shaft gear  566  are provided to be rotated in directions opposite to each other, it is understood that the number of shaft gears is not limited to the description provided herein. 
     The hinge structure  500  may include a shaft bracket  519  provided to rotatably support ends of the first axis shaft  511  and the second axis shaft  561 . As the shaft bracket  519  is rotatably coupled to the first axis shaft  511  and the second axis shaft  561 , it is possible to prevent the components coupled to the first axis shaft  511  and the second axis shaft  561  from being separated. 
     According to this configuration, during rotation of the first axis shaft  511  and the second axis shaft  561  of the hinge structure  500 , the first housing  310  and the second housing  320  may be rotated. 
     Because the hinge structure  500  is provided such that the components interlocked with the first axis shaft  511  are approximately symmetrical with the components interlocked with the second axis shaft  561 , for convenience of description, a configuration related to the first axis shaft  511  will be described in detail, and a configuration related to the second axis shaft  561  will be omitted but for brief descriptions thereof, in the interests of brevity. Further, components interlocked with the first axis shaft  511  are approximately symmetrical with the first housing coupling portion  514 , and for convenience of description, components located on one side of the first housing coupling portion  514  will be described. 
     The hinge structure  500  may include sliding cams  541 ,  542 ,  543 , and  544  rotatably and slidably coupled to the first axis shaft  511 . The sliding cams  541 ,  542 ,  543 , and  544  may include a first sliding cam  541 , a second sliding cam  542 , a third sliding cam  543 , and a fourth sliding cam  544 . The first sliding cam  541 , the second sliding cam  542 , the third sliding cam  543 , and the fourth sliding cam  544  may be coupled to the axis shaft  511  not to be rotated but to be moved linearly along the axis shaft  511  in response to rotation of the axis shaft  511 . 
     The hinge structure  500  may include sliding cams  591 ,  592 ,  593 , and  594  rotatably and slidably coupled to the second axis shaft  561 . The sliding cams  591 ,  592 ,  593 , and  594  may include a fifth sliding cam  591 , a sixth sliding cam  592 , a seventh sliding cam  593 , and an eighth sliding cam  594 . The fifth sliding cam  591 , the sixth sliding cam  592 , the seventh sliding cam  593 , and the eighth sliding cam  594  may correspond to the first sliding cam  541 , the second sliding cam  542 , the third sliding cam  543 , and the fourth sliding cam  544 , respectively. 
     The hinge structure  500  may include a first bridge  541   b  extending between the first sliding cam  541  and the fifth sliding cam  591 . By the first bridge  541   b , the first sliding cam  541  may slide without rotating even when the first axis shaft  511  is rotated, and the fifth sliding cam  591  may slide without rotating even when the second axis shaft  561  is rotated. The hinge structure  500  may include a second bridge  542   b  extending between the second sliding cam  542  and the sixth sliding cam  592 . By the second bridge  542   b , the second sliding cam  542  may slide without rotating even when the first axis shaft  511  is rotated, and the sixth sliding cam  592  may slide without rotating even when the second axis shaft  561  is rotated. The hinge structure  500  may include a third bridge  543   b  extending between the third sliding cam  543  and the seventh sliding cam  593 . By the third bridge  543   b , the third sliding cam  543  may slide without rotating even when the first axis shaft  511  is rotated, and the seventh sliding cam  593  may slide without rotating even when the second axis shaft  561  is rotated. The hinge structure  500  may include a fourth bridge  544   b  extending between the fourth sliding cam  544  and the eighth sliding cam  594 . By the fourth bridge  544   b , the fourth sliding cam  544  may slide without rotating even when the first axis shaft  511  is rotated, and the eighth sliding cam  594  may slide without rotating even when the second axis shaft  561  is rotated. 
     The first sliding cam  541  may be engaged with a first rotation cam  531 , the second sliding cam  542  and the third sliding cam  543  may be engaged with a second rotation cam  532 , and the fourth sliding cam  544  may be engaged with a third rotation cam  533 . 
     The fifth sliding cam  591  may be engaged with a fourth rotation cam  581 , the sixth sliding cam  592  and the seventh sliding cam  593  may be engaged with a fifth rotation cam  582 , and the eighth sliding cam  594  may be engaged with a sixth rotation cam  583 . 
     The first sliding cam  541  may include a first sliding cam nose  541   a . The first sliding cam nose  541   a  may be a protruding portion of the first sliding cam  541 , and is formed to engage and interact with a first rotation cam nose  531   a  of the first rotation cam  531 . The second sliding cam  542  may include a second sliding cam nose  542   a . The second sliding cam nose  542   a  may be a protruding portion of the second sliding cam  542 , and is formed to engage and interact with a second rotation cam nose  532   a  of the second rotation cam  532 . The third sliding cam  543  may include a third sliding cam nose  543   a . The third sliding cam nose  543   a  may be a protruding portion of the third sliding cam  543 , and is formed to engage and interact with a third rotation cam nose  532   b  of the second rotation cam  532 . The fourth sliding cam  544  may include a fourth sliding cam nose  544   a . The fourth sliding cam nose  544   a  may be a protruding portion of the fourth sliding cam  544 , and is formed to engage and interact with a fourth rotation cam nose  533   a  of the third rotation cam  533 . 
     The fifth sliding cam  591  may include a fifth sliding cam nose  591   a . The sixth sliding cam  592  may include a sixth sliding cam nose  592   a . The seventh sliding cam  593  may include a seventh sliding cam nose  593   a . The eighth sliding cam  594  may include an eighth sliding cam nose  594   a . The fifth sliding cam nose  591   a , the sixth sliding cam nose  592   a , the seventh sliding cam nose  593   a , and the eighth sliding cam nose  594   a  may correspond to the first sliding cam nose  541   a , the second sliding cam nose  542   a , the third sliding cam nose  543   a , and the fourth sliding cam nose  544   a , respectively. 
     The first sliding cam nose  541   a , the second sliding cam nose  542   a , the third sliding cam nose  543   a , and the fourth sliding cam nose  544   a  may be provided at an approximately same position along a radial direction from the first axis shaft  511 . In other words, the first sliding cam nose  541   a , the second sliding cam nose  542   a , the third sliding cam nose  543   a , and the fourth sliding cam nose  544   a  may be located on approximately a same (imaginary) line. 
     A first elastic member  546  may be provided between the first sliding cam  541  and the second sliding cam  542 . The first elastic member  546  may be provided to apply an elastic force, along a direction in which the first sliding cam  541  and the second sliding cam  542  are movable away from each other, towards the first sliding cam  541  and the second sliding cam  542 . 
     As mentioned above, in a state in which the first sliding cam  541  and the second sliding cam  542  are configured to share the first elastic member  546 , it is possible to reduce a size thereof in comparison with a state in which an elastic member provided to elastically press the first sliding cam  541  toward the first rotation cam  531  and an elastic member provided to elastically press the second sliding cam  542  toward the second rotation cam  532  are respectively provided. 
     A second elastic member  547  may be provided between the third sliding cam  543  and the fourth sliding cam  544 . The second elastic member  547  may be provided to apply an elastic force, along a direction in which the third sliding cam  543  and the fourth sliding cam  544  are movable away from each other, towards the third sliding cam  543  and the fourth sliding cam  544 . 
     As mentioned above, in a state in which the third sliding cam  543  and the fourth sliding cam  544  are configured to share the second elastic member  547 , it is possible to reduce a size thereof in comparison with a state in which an elastic member provided to elastically press the third sliding cam  543  toward the second rotation cam  532  and an elastic member provided to elastically press the fourth sliding cam  544  toward the third rotation cam  533  are respectively provided. 
     In other words, in the hinge structure  500  according to the embodiment of the disclosure, the first sliding cam  541  and the second sliding cam  542  are configured to share the first elastic member  546 , and the third sliding cam  543  and the fourth sliding cam  544  are configured to share the second elastic member  547 , and thus it is possible to reduce a size thereof in comparison with a state in which an elastic member for the first sliding cam  541 , an elastic member for the second sliding cam  542 , an elastic member for the third sliding cam  543  and an elastic member for the fourth sliding cam  544  are individually provided. 
     A third elastic member  596  may be provided between the fifth sliding cam  591  and the sixth sliding cam  592 . The third elastic member  596  may be provided to apply an elastic force, along a direction in which the fifth sliding cam  591  and the sixth sliding cam  592  are movable away from each other, towards the fifth sliding cam  591  and the sixth sliding cam  592 . The third elastic member  596  may correspond to the first elastic member  546 . 
     A fourth elastic member  597  may be provided between the seventh sliding cam  593  and the eighth sliding cam  594 . The fourth elastic member  597  may be provided to apply an elastic force, along a direction in which the seventh sliding cam  593  and the eighth sliding cam  594  are movable away from each other, towards the seventh sliding cam  593  and the eighth sliding cam  594 . The fourth elastic member  597  may correspond to the second elastic member  547 . 
     The hinge structure  500  may include a first cam body  530  coupled to the first housing coupling portion  514 . The first cam body  530  may be coupled to the first housing coupling portion  514  by a first sliding shaft  518 . The first sliding shaft  518  may be rotatably coupled to the first cam body  530 . The first sliding shaft  518  may be slidably coupled to the first housing coupling portion  514 . The first sliding shaft  518  may guide the first housing coupling portion  514  to allow the first housing coupling portion  514  to be rotated and moved in response to rotation of the first cam body  530 . By the structure, when the first housing  310  and the second housing  320  are disposed in the folded configuration, the first region  201  and the second region  202  of the display  200  may be moved and rotated to face each other. 
     The hinge structure  500  may include a second cam body  580  coupled to the second housing coupling portion  564 . The second cam body  580  may be coupled to the second housing coupling portion  564  by a second sliding shaft  568 . The second cam body  580  and the second sliding shaft  568  may correspond to the first cam body  530  and the first sliding shaft  518 . 
     The first cam body  530  may include the first rotation cam  531 , the second rotation cam  532 , and the third rotation cam  533 . The first rotation cam  531 , the second rotation cam  532 , and the third rotation cam  533  may be fixed to the first axis shaft  511  to be rotatable together with the first axis shaft  511 . The first rotation cam  531  may engage and interact with the first sliding cam  541 . The second rotation cam  532  may engage and interact with the second sliding cam  542 , and the third sliding cam  543 . The third rotation cam  533  may engage and interact with the fourth sliding cam  544 . 
     The second cam body  580  may include the fourth rotation cam  581 , the fifth rotation cam  582 , and the sixth rotation cam  583 . The fourth rotation cam  581 , the fifth rotation cam  582 , and the sixth rotation cam  583  may correspond to the first rotation cam  531 , the second rotation cam  532 , and the third rotation cam  533 , respectively. 
     The first rotation cam  531  may include the first rotation cam nose  531   a . The first rotation cam nose  531   a  is a protruding portion of the first rotation cam  531 , and is formed to engage and interact with the first sliding cam nose  541   a  of the first sliding cam  541 . The second rotation cam  532  may include the second rotation cam nose  532   a  and the third rotation cam nose  532   b . The second rotation cam nose  532   a  is a protruding portion of the second rotation cam  532 , and is formed to engage and interact with the second sliding cam nose  542   a  of the second sliding cam  542 . The third rotation cam nose  532   b  is a protruding portion of the second rotation cam  532 , and is formed to engage and interact with the third sliding cam nose  543   a  of the third sliding cam  543 . The second rotation cam  532  may be formed in such a way that the second rotation cam nose  532   a  is formed on one surface facing the second sliding cam  542 , and the third rotation cam nose  532   b  is formed on one surface facing the third sliding cam  543 . The third rotation cam nose  532   b  may be formed on a surface opposite to the surface on which the second rotation cam nose  532   a  is formed. The third rotation cam  533  may include the fourth sliding cam nose  533   a . The fourth rotation cam nose  533   a  is a protruding portion of the third rotation cam  533 , and is formed to engage and interact with the fourth sliding cam nose  544   a  of the fourth sliding cam  544 . 
     The fourth rotation cam  581  may include the fifth rotation cam nose  581   a . The fifth rotation cam  582  may include the sixth rotation cam nose  582   a  and the seventh rotation cam nose  582   b . The sixth rotation cam  583  may include the eighth sliding cam nose  583   a . The fifth rotation cam nose  581   a , the sixth rotation cam nose  582   a , the seventh rotation cam nose  582   b , and the eighth rotation cam nose  583   a  may correspond to the first rotation cam nose  531   a , the second rotation cam nose  532   a , the third rotation cam nose  532   b , and the fourth rotation cam nose  533   a , respectively. 
     The first rotation cam  531  may be moved according to a relative position of the first rotation cam nose  531   a  with respect to the first sliding cam nose  541   a  of the first sliding cam  541 . The second rotation cam  532  may be moved according to a relative position of the second rotation cam nose  532   a  with respect to the second sliding cam nose  542   a  of the second sliding cam  542  or according to a relative position of the third rotation cam nose  532   b  with respect to the third sliding cam nose  543   a  of the third sliding cam  543 . The fourth rotation cam  581  may be moved according to a relative position of the fourth rotation cam nose  533   a  with respect to the fourth sliding cam nose  544   a  of the fourth sliding cam  544 . 
     The first rotation cam nose  531   a , the second rotation cam nose  532   a , the third rotation cam nose  532   b , and the fourth sliding cam nose  533   a  may be arranged at different positions from each other along the radial direction from the first axis shaft  511 . In other words, the first rotation cam nose  531   a , the second rotation cam nose  532   a , the third rotation cam nose  532   b , and the fourth rotation cam nose  533   a  may be located on different lines from each other. 
     Particularly, referring to  FIG. 7 , the first sliding cam nose  541   a , the second sliding cam nose  542   a , the third sliding cam nose  543   a , and the fourth sliding cam nose  544   a  may be extended to be positioned on the same line. However, the first rotation cam nose  531   a , the second rotation cam nose  532   a , the third rotation cam nose  532   b , and the fourth rotation cam nose  533   a  may be extended to be positioned on different lines from each other. That is, an imaginary line, on which the first rotation cam nose  531   a  is extended, is different from imaginary lines on which the second rotation cam nose  532   a , the third rotation cam nose  532   b , and the fourth rotation cam nose  533   a  are extended. An imaginary line, on which the second rotation cam nose  532   a  is extended, is different from imaginary lines on which the third rotation cam nose  532   b , and the fourth rotation cam nose  533   a  are extended. An imaginary line, on which the third rotation cam nose  532   b  is extended, is different from an imaginary line on which the fourth rotation cam nose  533   a  is extended. 
     By the configuration, a position in which the first rotation cam nose  531   a  interacts with the first sliding cam nose  541   a  is different from a position in which the second rotation cam nose  532   a  interacts with the second sliding cam nose  542   a , a position in which the third rotation cam nose  532   b  interacts with the third sliding cam nose  543   a  and a position in which the fourth rotation cam nose  533   a  interacts with the fourth sliding cam nose  544   a . The position in which the second rotation cam nose  532   a  interacts with the second sliding cam nose  542   a  is different from the position in which the third rotation cam nose  532   b  interacts with the third sliding cam nose  543   a  and the position in which the fourth rotation cam nose  533   a  interacts with the fourth sliding cam nose  544   a . The position in which the third rotation cam nose  532   b  interacts with the third sliding cam nose  543   a  is different from the position in which the fourth rotation cam nose  533   a  interacts with the fourth sliding cam nose  544   a.    
     Accordingly, the hinge structure  500  may set various stopping angles between the first housing  310  and the second housing  320  by variously combining the position in which the first rotation cam nose  531   a  interacts with the first sliding cam nose  541   a , the position in which the second rotation cam nose  532   a  interacts with the second sliding cam nose  542   a , the position in which the third rotation cam nose  532   b  interacts with the third sliding cam nose  543   a  and the position in which the fourth rotation cam nose  533   a  interacts with the fourth sliding cam nose  544   a . Hereinafter the configuration will be described in detail with reference to  FIGS. 7 to 16 . 
       FIG. 7  is a rear view illustrating an unfolded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure.  FIG. 8  is an enlarged view of part A shown in  FIG. 7 .  FIG. 9  is a side view illustrating the unfolded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure. 
     Referring to  FIGS. 7 to 9 , the hinge structure  500  may be set in the unfolded state. 
     Particularly, as for the components coupled to the first axis shaft  511 , the first rotation cam nose  531   a  of the first rotation cam  531  is disposed as to contact and interact with the first sliding cam nose  541   a  of the first sliding cam  541 . That is, an end of the first rotation cam nose  531   a  is out of a flat section of the first sliding cam  541  and is in a position proximate to the end of the first sliding cam nose  541   a.    
     At this time, the second rotation cam nose  532   a  of the second rotation cam  532  is in a position in which the second rotation cam nose  532   a  does not come into contact so as not to interact with the second sliding cam nose  542   a  of the second sliding cam  542 . The third rotation cam nose  532   b  of the second rotation cam  532  is in a position in which the third rotation cam nose  532   b  does not come into contact so as not to interact with the third sliding cam nose  543   a  of the third sliding cam  543 . The fourth rotation cam nose  533   a  of the third rotation cam  533  is in a position in which the fourth rotation cam nose  533   a  does not come into contact so as not to interact with the fourth sliding cam nose  544   a  of the fourth sliding cam  544 . That is, the end of the second rotation cam nose  532   a  is spaced apart from the second sliding cam nose  542   a  and is located in a flat section of the second sliding cam  542 . The end of the third rotation cam nose  532   b  is spaced apart from the third sliding cam nose  543   a  and is located in a flat section of the third sliding cam  543 . The end of the fourth rotation cam nose  533   a  is spaced apart from the fourth sliding cam nose  544   a  and is located in a flat section of the fourth sliding cam  544 . 
     The first elastic member  546  may apply a force to the first sliding cam  541  in a direction in which the first sliding cam  541  moves away from the second sliding cam  542  (i.e., R-direction in  FIG. 7 ). That is, the first sliding cam  541  receives a force in a direction proximate to the first rotation cam  531 . Accordingly, the first rotation cam nose  531   a  receives a force causing it to move to a position, in which the end of the first rotation cam nose  531   a  is moved away from the end of the first sliding cam nose  541   a  so as not to interact with the first sliding cam nose  541   a  (e.g., in  FIG. 7 , the first rotation cam nose  531   a  in contact with an upper surface of the first sliding cam nose  541   a  receives a force that is to move further upward toward the flat section of the first sliding cam  541 ). That is, the first rotation cam  531  receives a force along a direction in which the first housing  310  and the second housing  320  unfolded relative to each other. 
     In this case, the first housing coupling portion  514  coupled to the first cam body  530  is in a state, in which, during rotation in a direction as to unfold the device (e.g., in  FIG. 7 , the first rotation cam nose  531   a  in contact with the upper surface of the first sliding cam nose  541   a  is rotated in a direction of moving further upward toward the flat section of the first sliding cam  541 ) is limited by the hinge body  512 , and thus the rotation of the first rotation cam  531  for separating the first housing  310  and the second housing  320  into the unfolded state is limited. That is, in the first rotation cam  531 , an elastic force received from the first elastic member  546  and a force supported by the hinge body  512  are balanced, and thus the first rotation cam nose  531   a  may maintain a position with respect to the first sliding cam nose  541   a.    
     The sliding cams  591 ,  592 ,  593 , and  594  coupled to the second axis shaft  561  and the rotation cams  581 ,  582 , and  583  engaged therewith are operated in the same manner as the above-mentioned sliding cams  541 ,  542 ,  543 , and  544  coupled to the first axis shaft  511  and the rotation cams  531 ,  532 , and  533  engaged therewith, and thus a detailed description thereof will be omitted. 
       FIG. 10  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a first angle according to certain embodiments of the disclosure.  FIG. 11  is an enlarged view of part B shown in  FIG. 10 .  FIG. 12  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the first angle according to certain embodiments of the disclosure. 
     Referring to  FIGS. 10 to 12 , the hinge structure  500  may be fixed at a position in which the first housing  310  and the second housing  320  form approximately a 130° angle. The angle shown in  FIG. 10  may be referred to as a first angle. 
     Particularly, the first rotation cam nose  531   a  of the first rotation cam  531  may cross the end of the first sliding cam nose  541   a  of the first sliding cam  541 , and may be moved in the opposite direction (e.g., in the case of the first rotation cam nose  531   a  in contact with the upper surface of the first sliding cam nose  541   a  in  FIG. 7 , it is downward). Because the first elastic member  546  applies a force in a direction in which the first sliding cam  541  moves away from the second sliding cam  542 , the first sliding cam  541  may receive a force having directionality towards the first rotation cam  531  (R-direction in  FIG. 10 ). That is, the first rotation cam nose  531   a  receives a force having directionality pointing away from the end of the first sliding cam nose  541   a . That is, the first rotation cam  531  may receive a force in the direction in which the first housing  310  and the second housing  320  are folded (a direction in which the first rotation cam nose  531   a  in contact with a lower surface of the first sliding cam nose  541   a  in  FIG. 10  is further moved downward). 
     On the other hand, the third rotation cam nose  532   b  of the second rotation cam  532  may be disposed in a position of contacting and interacting with the third sliding cam nose  543   a  of the third sliding cam  543 . At this time, because the second elastic member  547  presses the third sliding cam  543  in a direction away from the fourth sliding cam  544 , the third rotation cam nose  532   b  may receive a force in a direction away from the third sliding cam nose  543   a . That is, the second rotation cam  532  receives a force in the direction by which the first housing  310  and the second housing  320  are unfolded (a direction in which the third rotation cam nose  532   b  in contact with the upper surface of the third sliding cam nose  543   a  in  FIG. 10  is moved further upwards). 
     That is, when described based on the components located below in  FIG. 10 , because the first rotation cam nose  531   a  is located below the first sliding cam nose  541   a  and the third rotation cam nose  532   b  is located above the third sliding cam nose  543   a , the rotational force applied to the first cam body  530  may be balanced. Accordingly, the positions of the first housing  310  and the second housing  320  may be fixed without unfolding or folding. 
     The second rotation cam nose  532   a  of the second rotation cam  532  and the second sliding cam nose  542   a  of the second sliding cam  542  are located in positions in which the second rotation cam nose  532   a  and the second sliding cam nose  542   a  are not in contact with each other and do not interact with each other. That is, the second rotation cam nose  532   a  is positioned in a flat section of the second sliding cam  542 , and the second sliding cam nose  542   a  is positioned in a flat section of the second rotation cam  532 . 
     The fourth rotation cam nose  533   a  of the third rotation cam  533  and the fourth sliding cam nose  544   a  of the fourth sliding cam  544  are located in positions in which the fourth rotation cam nose  533   a  and the fourth sliding cam nose  544   a  are not in contact with each other and do not interact with each other. That is, the fourth rotation cam nose  533   a  is positioned in a flat section of the fourth sliding cam  544 , and the fourth sliding cam nose  544   a  is positioned in the flat section of the second rotation cam  532 . 
     In response to rotation of the first cam body  530 , the first sliding shaft  518  slides along the guide slit  514   a  of the first housing coupling portion  514 , and the first coupling portion guide  515  is guided by the first body guide  513   a . Accordingly, the first housing coupling portion  514  is rotated and moved in a direction in which the first region  201  and the second region  202  of the display  200  face each other. 
     The sliding cams  591 ,  592 ,  593 , and  594  coupled to the second axis shaft  561  and the rotation cams  581 ,  582 , and  583  engaged therewith are operated in the same manner as the above-mentioned sliding cams  541 ,  542 ,  543 , and  544  coupled to the first axis shaft  511  and the rotation cams  531 ,  532 , and  533  engaged therewith, and thus a detailed description thereof will be omitted. 
       FIG. 13  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a second angle according to certain embodiments of the disclosure.  FIG. 14  is an enlarged view of part C shown in  FIG. 13 .  FIG. 15  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the second angle according to certain embodiments of the disclosure. 
     Referring to  FIGS. 13 to 15 , the hinge structure  500  may be fixed at a position in which an angle between the first housing  310  and the second housing  320  forms approximately 90°. The angle shown in  FIG. 13  may be referred to as a second angle. 
     Particularly, the first rotation cam nose  531   a  is moved to a position in which the first rotation cam nose  531   a  is not in contact with and does not interact with the first sliding cam nose  541   a . At the same time, the second rotation cam nose  532   a  is moved to a position of contacting and interacting with the second sliding cam nose  542   a . That is, the second rotation cam nose  532   a  is out of the flat section of the second sliding cam  542  and is in a position close to the end of the second sliding cam nose  542   a . Accordingly, referring to  FIG. 13 , the first sliding cam  541 , the second sliding cam  542 , and the first elastic member  546  are moved together in the R-direction. Because the first elastic member  546  applies a force in a direction in which the second sliding cam  542  is away from the first sliding cam  541 , the second sliding cam  542  receives a force in a direction closer to the second rotation cam  532 . Accordingly, the second rotation cam nose  532   a  receives a force in a direction away from the end of the second sliding cam nose  542   a . That is, referring to  FIG. 13 , the second rotation cam nose  532   a  in contact with the upper surface of the second sliding cam nose  542   a  receives a force in a direction of moving further upward (a direction in which the first housing  310  and the second housing  320  are unfolded). 
     Meanwhile, the third rotation cam nose  532   b  crosses the end of the third sliding cam nose  543   a  and is moved to the opposite direction. That is, the third rotation cam nose  532   b  in contact with the upper surface of the third sliding cam nose  543   a  as shown in  FIG. 10  is moved to contact a lower surface of the third sliding cam nose  543   a  as shown in  FIG. 13 . Because the second elastic member  547  applies a force in a direction in which the third sliding cam  543  is moved away from the fourth sliding cam  544 , the third sliding cam  543  receives a force in a direction closer to the second rotation cam  532 . Accordingly, the third rotation cam nose  532   b  receives a force in a direction away from the end of the third sliding cam nose  543   a  (the direction in which the first housing  310  and the second housing  320  are folded). 
     That is, when described based on the components located below in  FIG. 13 , because the second rotation cam nose  532   a  is located on the upper surface of the second sliding cam nose  542   a  and the third rotation cam nose  532   b  is located on the lower surface of the third sliding cam nose  543   a , the rotational force applied to the first cam body  530  is balanced. Accordingly, the positions of the first housing  310  and the second housing  320  may be fixed without folding or unfolding. 
     The fourth rotation cam nose  533   a  of the third rotation cam  533  is located in a position in which the fourth rotation cam nose  533   a  is not in contact with and does not interact with the fourth sliding cam nose  544   a . That is, the fourth rotation cam nose  533   a  is positioned in a flat section of the fourth sliding cam  544 . 
     In response to rotation of the first cam body  530 , the first sliding shaft  518  slides along the guide slit  514   a  of the first housing coupling portion  514 , and the first coupling portion guide  515  is guided by the first body guide  513   a . Accordingly, the first housing coupling portion  514  is rotated and moved in a direction in which the hinge cover  330  is exposed. 
     The sliding cams  591 ,  592 ,  593 , and  594  coupled to the second axis shaft  561  and the rotation cams  581 ,  582 , and  583  engaged therewith are operated in the same manner as the above-mentioned sliding cams  541 ,  542 ,  543 , and  544  coupled to the first axis shaft  511  and the rotation cams  531 ,  532 , and  533  engaged therewith, and thus a detailed description thereof will be omitted. 
       FIG. 16  is a rear view illustrating a state in which the hinge structure provided in the electronic device is fixed at a third angle according to certain embodiments of the disclosure.  FIG. 17  is an enlarged view of part D shown in  FIG. 16 .  FIG. 18  is a side view illustrating the state in which the hinge structure provided in the electronic device is fixed at the third angle according to certain embodiments of the disclosure. 
     Referring to  FIGS. 16 to 18 , the hinge structure  500  may be fixed at a position in which an angle between the first housing  310  and the second housing  320  forms approximately 50°. The angle shown in  FIG. 13  may be referred to as a third angle. 
     Particularly, the third rotation cam nose  532   b  is moved to a position in which the third rotation cam nose  532   b  is not in contact with and does not interact with the third sliding cam nose  543   a . At the same time, the fourth rotation cam nose  533   a  is moved to a position of contacting and interacting with the fourth sliding cam nose  544   a . That is, the fourth rotation cam nose  533   a  is out of the flat section of the fourth sliding cam  544  and is in a position close to the end of the fourth sliding cam nose  544   a . Accordingly, referring to  FIG. 16 , the fourth sliding cam  544 , the third sliding cam  543 , and the second elastic member  547  are moved together in the R-direction. Because the second elastic member  547  applies a force in a direction in which the fourth sliding cam  544  is away from the third sliding cam  543 , the fourth sliding cam  544  receives a force in a direction closer to the third rotation cam  533 . Accordingly, the fourth rotation cam nose  533   a  receives a force in a direction away from the end of the fourth sliding cam nose  544   a . That is, referring to  FIG. 16 , the fourth rotation cam nose  533   a  in contact with the upper surface of the fourth sliding cam nose  544   a  receives a force in a direction of moving further upward (the direction in which the first housing  310  and the second housing  320  are unfolded). 
     Meanwhile, the second rotation cam nose  532   a  crosses the end of the second sliding cam nose  542   a  and is moved to the opposite direction. That is, the second rotation cam nose  532   a  in contact with the upper surface of the second sliding cam nose  542   a  as shown in  FIG. 13  is moved to contact the lower surface of the second sliding cam nose  542   a , as shown in  FIG. 16 . Because the first elastic member  546  applies a force in a direction in which the second sliding cam  542  is away from the first sliding cam  541 , the second sliding cam  542  receives a force in a direction closer to the second rotation cam  532 . Accordingly, the second rotation cam nose  532   a  receives a force in a direction away from the end of the second sliding cam nose  542   a  (the direction in which the first housing  310  and the second housing  320  are folded). 
     That is, when described based on the components located below in  FIG. 16 , because the second rotation cam nose  532   a  is located on the lower surface of the second sliding cam nose  542   a  and the fourth rotation cam nose  533   a  is located on the upper surface of the fourth sliding cam nose  544   a , the rotational force applied to the first cam body  530  is balanced. Accordingly, the positions of the first housing  310  and the second housing  320  may be fixed without folding or unfolding. 
     The first rotation cam nose  531   a  of the first rotation cam  531  is located in a position in which the first rotation cam nose  531   a  is not in contact with and does not interact with the first sliding cam nose  541   a  of the first sliding cam  541 . That is, the first rotation cam nose  531   a  is positioned in a flat section of the first sliding cam  541 . 
     In response to rotation of the first cam body  530 , the first sliding shaft  518  slides along the guide slit  514   a  of the first housing coupling portion  514 , and the first coupling portion guide  515  is guided by the first body guide  513   a . Accordingly, the first housing coupling portion  514  is rotated and moved in a direction in which the hinge cover  330  is exposed. 
     The sliding cams  591 ,  592 ,  593 , and  594  coupled to the second axis shaft  561  and the rotation cams  581 ,  582 , and  583  engaged therewith are operated in the same manner as the above-mentioned sliding cams  541 ,  542 ,  543 , and  544  coupled to the first axis shaft  511  and the rotation cams  531 ,  532 , and  533  engaged therewith, and thus a detailed description thereof will be omitted. 
       FIG. 19  is a rear view illustrating a folded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure.  FIG. 20  is an enlarged view of part E shown in  FIG. 19 .  FIG. 21  is a side view illustrating the folded state of the hinge structure provided in the electronic device according to certain embodiments of the disclosure. 
     Referring to  FIGS. 19 to 21 , the hinge structure  500  may be fixed in the state in which the first housing  310  and the second housing  320  are folded. 
     Particularly, the second rotation cam nose  532   a  is moved to a position in which the second rotation cam nose  532   a  is not in contact with and does not interact with the second sliding cam nose  542   a . That is, the second rotation cam nose  532   a  is positioned in a flat section of the second sliding cam  542 . 
     The fourth rotation cam nose  533   a  may cross the end of the fourth sliding cam nose  544   a  and is moved to the opposite direction. That is, the fourth rotation cam nose  533   a  may be in contact with the upper surface of the fourth sliding cam nose  544   a  as shown in  FIG. 16 , and may be moved to contact the lower surface of the fourth sliding cam nose  544   a , as shown in  FIG. 19 . Because the second elastic member  547  applies a force in a direction in which the fourth sliding cam  544  is moved away from the third sliding cam  543 , the fourth sliding cam  544  receives a force in a direction coming closer to the fourth rotation cam  533 . Accordingly, the fourth rotation cam nose  533   a  receives a force in a direction away from the end of the fourth sliding cam nose  544   a  (the direction in which the first housing  310  and the second housing  320  are folded). 
     In this case, because of the limitation imposed on the first housing coupling portion  514  coupled to the first cam body  530  being rotated towards the folding direction, by the hinge body  512 , the rotational force applied to the first cam body  530  is balanced and the first housing  310  and the second housing  320  do not rotate and maintain positions thereof. 
     In response to rotation of the first cam body  530 , the first sliding shaft  518  may slide along the guide slit  514   a  of the first housing coupling portion  514 , and the first coupling portion guide  515  is guided by the first body guide  513   a . Accordingly, the first housing coupling portion  514  is rotated and moved in a direction in which the first region  201  and the second region  202  of the display  200  are closed to each other. 
     The sliding cams  591 ,  592 ,  593 , and  594  coupled to the second axis shaft  561  and the rotation cams  581 ,  582 , and  583  engaged therewith are operated in the same manner as the above-mentioned sliding cams  541 ,  542 ,  543 , and  544  coupled to the first axis shaft  511  and the rotation cams  531 ,  532 , and  533  engaged therewith, and thus a detailed description thereof will be omitted. 
     As is apparent from the above description, because a foldable flexible display device and an electronic device are configured such that a plurality of rotation cams and a plurality of sliding cams are coupled in various combinations, it is possible set various angles between a first housing and a second housing so as to implement stable fixation. 
     According to certain embodiments, each component (e.g., a module or a program) of the above-described components may include a singular or a plurality of entities, and some of the plurality of entities may be separately arranged in other components. According to certain embodiments, one or more components or operations among the above-described corresponding components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., a module or a program) may be integrated into one component. In this case, the integrated component may perform one or more functions of each component of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. Operations performed by a module, a program module, or other elements according to certain embodiments of the present disclosure may be executed sequentially, in parallel, repeatedly, or in a heuristic method. Also, a portion of operations may be executed in different sequences, omitted, or other operations may be added. 
     Although a few embodiments of the disclosure have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles of the disclosure, the scope of which is defined in the claims and their equivalents.