Patent Publication Number: US-2023151656-A1

Title: Foldable hinge and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority to Chinese Patent Application No. 202111342141.8 filed on Nov. 12, 2021, the entire contents of which are incorporated herein by reference for all purposes. 
     BACKGROUND 
     With the development of technology, foldable screens are widely used in the technical field of electronic equipment, and the technology for drop-shaped foldable screens is relatively mature at present. Foldable hinges of such foldable screens can help achieve the folding function while avoiding damage to the screen because the folding angle is too big. 
     In order to configure the foldable screens to be drop-shaped, the foldable hinges usually have many elements, resulting in a complex structure of the foldable hinges. 
     SUMMARY 
     The present disclosure relates to the field of electronic equipment and, more particularly, to a foldable hinge and an electronic device. 
     Embodiments of the present disclosure propose a foldable hinge that includes a base and two folding assemblies on both sides of the base and coupled to the base, and the two folding assemblies are foldable relative to each other. Each folding assembly includes a rotating arm and a support member; a first end of the rotating arm is rotatably coupled to the base; the support member is rotatably coupled to a second end of the rotating arm away from the base; a side of the support member close to the base is rotatably coupled to the base and the support member is slidable in a direction approaching or away from the base. A distance between portions of two support members coupled to the rotating arms is smaller than a distance between portions of the two support members coupled to the base in response to bringing the two folding assemblies together. 
     In another aspect, embodiments of the present disclosure propose an electronic device, including two housings, a flexible screen, and a foldable hinge. The foldable hinge includes a base and two folding assemblies on both sides of the base and coupled to the base, and the two folding assemblies are foldable relative to each other. Each folding assembly includes a rotating arm and a support member; a first end of the rotating arm is rotatably coupled to the base; the support member is rotatably coupled to a second end of the rotating arm away from the base; a side of the support member close to the base is rotatably coupled to the base and the support member is slidable in a direction approaching or away from the base. A distance between portions of two support members coupled to the rotating arms is smaller than a distance between portions of the two support members coupled to the base in response to bringing the two folding assemblies together. The two housings are coupled to rotating arms of the two folding assemblies correspondingly, and the flexible screen is coupled to the two housings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order to illustrate the technical solutions in embodiments of the present disclosure more clearly, the accompanying drawings used in the description of the embodiments will be described briefly. The accompanying drawings described below merely show some of the embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art based on these accompanying drawings, without involving any inventive work. 
         FIG.  1    is a schematic diagram showing an electronic device in accordance with an embodiment of the present disclosure; 
         FIG.  2    is a schematic diagram showing a foldable hinge in accordance with an embodiment of the present disclosure; 
         FIG.  3    is a schematic diagram showing a part of a base in accordance with an embodiment of the present disclosure; 
         FIG.  4    is a schematic diagram showing a rotating arm in accordance with an embodiment of the present disclosure; 
         FIG.  5    is a schematic diagram showing connection between a rotating arm and a base in accordance with an embodiment of the present disclosure; 
         FIG.  6    is a schematic diagram showing a part of a support member in accordance with an embodiment of the present disclosure; 
         FIG.  7    is a schematic diagram showing a part of a folded hinge in a folded state in accordance with an embodiment of the present disclosure; 
         FIG.  8    is a schematic diagram showing a part of a folded hinge in an unfolded state in accordance with an embodiment of the present disclosure; 
         FIG.  9    is a schematic diagram showing a second support plate in accordance with an embodiment of the present disclosure; 
         FIG.  10    is a schematic diagram showing a foldable hinge in accordance with an embodiment of the present disclosure; 
         FIG.  11    is a schematic diagram showing installation of a second support plate in accordance with an embodiment of the present disclosure; 
         FIG.  12    is a partially exploded view of a foldable hinge in accordance with an embodiment of the present disclosure; 
         FIG.  13    is a schematic diagram showing a synchronizing swing arm in accordance with an embodiment of the present disclosure; 
         FIG.  14    is a schematic diagram showing a mounting shaft in accordance with an embodiment of the present disclosure; 
         FIG.  15    is a schematic diagram showing a damping ring in accordance with an embodiment of the present disclosure; 
         FIG.  16    is a schematic diagram showing a self-locking plate in accordance with an embodiment of the present disclosure; 
         FIG.  17    is a schematic diagram showing an electronic device in accordance with an embodiment of the present disclosure; 
         FIG.  18    is an exploded view of an electronic device in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Unless otherwise defined, technical terms or scientific terms used herein shall be understood in the ordinary sense as appreciated by those of ordinary skill in the art to which the present application belongs. Terms such as “first,” “second” and “third” used in the specification and claims are not intended to indicate any sequence, quantity or significance of indicated technical features, and are merely used to distinguish different elements. Likewise, the words “a,” “an” and the like used in the specification and claims are not intended to limit the quantity but indicate the presence of at least one element or device referred to by the words. The term “a plurality of” or “several” means two or more than two. Terms “comprising” or “containing” mean that the elements or articles before these terms “comprising” or “containing” includes the elements or articles listed after the terms “comprising” or “containing” and do not exclude other elements or articles. Terms “connected” or “coupled” and the like are not limited to physical or mechanical connection, but may include electrical connection, regardless of direct connection or indirect connection. Terms “up,” “down,” “left,” “right” and the like are merely used to indicate relative positions, and when an object described changes its absolute position, the relative positions may also change correspondingly. 
     In order to make the purpose, technical solutions and advantages of the present disclosure clearer, embodiments of the present disclosure will be described in detail in conjunction with the accompanying drawings. 
       FIG.  1    is a schematic diagram showing an electronic device in accordance with an embodiment of the present disclosure. As shown in  FIG.  1   , the electronic device includes a foldable hinge  300 , two middle frames  400 , and a flexible screen  200 . The two middle frames  400  are each coupled to the foldable hinge  300 . The flexible screen  200  is coupled to the two middle frames  400 . During a folding process of the electronic device, the two middle frames  400  may open and close relative to each other under an action of the foldable hinge  300 , and the flexible screen  200  may be bent under an action of the middle frames  400 . 
       FIG.  2    is a schematic diagram showing a foldable hinge in accordance with an embodiment of the present disclosure. As shown in  FIG.  2   , the foldable hinge includes a base  10  and two folding assemblies  20 . 
     The two folding assemblies  20  are on both sides of the base  10  and coupled to the base  10 , and the two folding assemblies  20  may open and close relative to each other, realizing a folding function of the foldable hinge. 
     As shown in  FIG.  2   , each folding assembly  20  includes a rotating arm  22  and a support member  21 . A first end of the rotating arm  22  is rotatably coupled to the base  10 , and the support member  21  is rotatably coupled to a second end of the rotating arm  22  away from the base  10 . A side of the support member  21  close to the base  10  is rotatably coupled to the base  10 , and the support member  21  is slidable in a direction approaching or away from the base  10 . When the two folding assemblies  20  are brought together, a distance L1 between portions of two support members  21  coupled to the rotating arms  22  is smaller than a distance L2 between portions of the two support members  21  coupled to the base  10 . 
     Since the first end of the rotating arm is rotatably coupled to the base, the support member is rotatably coupled to the second end of the rotating arm away from the base, and the side of the support member close to the base is rotatably coupled to the base, when the two folding assemblies are brought together, the rotating arms and the support members rotate relative to the base, and the support members can slide in the direction away from the base. Moreover, when the two folding assemblies are brought together, the distance between the portions of the two support members coupled to the rotating arms is smaller than the distance between the portions of the two support members coupled to the base, such that the two support members and the base form a drop-shaped receiving space, and no squeezing force or stretching force is exerted on the flexible screen when the flexible screen is received in the drop-shaped receiving space, preventing the flexible screen from creasing or even being damaged. In a process of relative unfolding of the two folding assemblies, the rotating arms and the support members rotate relative to the base, and the support members can slide in the direction approaching the base, such that the two support members are restored to an unfolded state, and the flexible screen is spread out on the two support members and the base. Three elements—the base, the rotating arms, and the support members—can form the drop-shaped receiving space, reducing the number of elements and making the structure simpler and more compact. 
     In some examples, each folding assembly  20  may include one or more rotating arms  22 . In an embodiment of the present disclosure, each folding assembly  20  includes two rotating arms  22  on a common side of the support member  21 , and the rotating arms  22  are close to two ends of the support member  21 . 
     When the foldable hinge is folded, the two support members  21  rotate facing each other; the two rotating arms  22  rotate facing each other; the support members  21  rotate relative to the rotating arms  22  and relative to the base  10 , and slide in the direction approaching the base  10 . When the foldable hinge is folded until the two folding assemblies  20  come together, the distance between the portions of the two support members  21  coupled to the rotating arms  22  is smaller than the distance between the portions of the two support members  21  coupled to the base  10 , and the two support members  21  and the base  10  enclose the drop-shaped receiving space. 
     When the foldable hinge is unfolded, the two support members  21  rotate in a direction away from each other; the two rotating arms  22  rotate in a direction away from each other; the support members  21  rotate relative to the rotating arms  22  and relative to the base  10 , and slides in the direction away from the base  10 . In a process that the foldable hinge is gradually unfolded, as the two support members  21  rotate in the direction away from each other relative to the base  10  and the two support members  21  slide in the direction away from the base  10 , the two support members  21  gradually rotate to a common surface, which can provide good support for the flexible screen. 
       FIG.  3    is a schematic diagram showing a part of a base in accordance with an embodiment of the present disclosure. As shown in  FIG.  3   , a surface of the base  10  has a first circular arc groove  11 . In an embodiment of the present disclosure, the first circular arc groove  11  is on a top surface of the base  10 . The top surface of the base  10  is a surface of the base  10  close to the flexible screen in the unfolded state. 
       FIG.  4    is a schematic diagram showing a rotating arm in accordance with an embodiment of the present disclosure. As shown in  FIG.  4   , the rotating arm  22  of the folding assembly  20  includes a first body portion  221  and a first arc arm  222 , and an end of the first arc arm  222  is coupled to the first body portion  221 . 
     The first body portion  221  also has a connection hole  221   a . By installing a screw into the connection hole  221   a , the rotating arm  22  can be coupled to two housings of the electronic device, such that the rotating arm  22  and the two housings are formed into one piece, which is beneficial to the installation of the flexible screen. 
       FIG.  5    is a schematic diagram showing connection between a rotating arm and a base in accordance with an embodiment of the present disclosure. As shown in  FIG.  5   , the first arc arm  222  is in the first arc groove  11  and is slidable along the first arc groove  11 . 
     By assembling the first arc arm  222  in the first circular arc groove  11 , the rotating arm  22  can rotate around an axis of the first arc groove  11  relative to the base  10 , realizing transition of the folding assembly from a flattened state to a closed state. The first arc arm  222  and the first arc groove  11  cooperate with each other to form a virtual axis type connection, which can hide a connection structure of the rotating arm  22  and the base  10  inside the base  10  and make the foldable hinge more compact. 
     In some examples, the first circular arc groove  11  may be a quarter arc, one-third arc, or the like, and the first arc arm  222  may be a quarter arc, one-third arc, or the like. A person skilled in the art can adapt specific parameters of the first circular arc groove  11  and the first arc arm  222  to actual needs. 
     In an embodiment of the present disclosure, each of the first circular arc groove  11  and the first arc arm  222  is a one-third arc. 
     As shown in  FIG.  3   , the first arc groove  11  also has an avoidance notch  111  at an opening of the first arc groove  11 . Referring to  FIG.  5   , the avoidance notch  111  is on a side wall of the base  10  close to the rotating arm  22 . The avoidance notch  111  can avoid the rotating arm  22 , so that the rotating arm  22  has more room for rotation. 
     When the folding assembly  20  is in the unfolded state, the rotating arm  22  is in the avoidance notch  111 , and the first arc arm  222  is mounted in the first arc groove  11 . During the folding of the folding assembly  20 , the rotating arm  22  rotates to an outer side of the avoidance notch  111 , and the first arc arm  222  slides along the first arc groove  11  toward an outer side of the first arc groove  11 . When the folding assembly  20  is in the folded state, an end of the first arc arm  222  away from the first body portion  221  is in the first circular arc groove  11 . 
     As shown in  FIG.  5   , the first body portion  221  of the rotating arm  22  has a second circular arc groove  2211 , an axis m1 of the second circular arc groove  2211  being parallel to an axis m2 of the first arc arm  222 . The second circular arc groove  2211  is used for connection with the support member  21 . 
       FIG.  6    is a schematic diagram showing a part of a support member in accordance with an embodiment of the present disclosure. As shown in  FIG.  6   , the support member  21  includes a first support plate  211 , a second arc arm  212 , and a connection block  213 , and an end of the second arc arm  212  is coupled to the first support plate  211 . 
     The connection block  213  and the second arc arm  212  are on a common side of the first support plate  211 , and the connection block  213  is coupled to the first support plate  211 . A half-moon-shaped side wall of the connection block  213  has a first guiding sliding slot  2131 . 
       FIG.  7    is a schematic diagram showing a part of a folded hinge in a folded state in accordance with an embodiment of the present disclosure. As shown in  FIG.  7   , the second arc arm  212  is in the second circular arc groove  2211  and is slidable along the second circular arc groove  2211 . 
     The second arc arm  212  is assembled in the second circular arc groove  2211  to achieve a rotational connection between the rotating arm  22  and the support member  21 , so that the rotating arm  22  has a certain degree of freedom of rotation. Cooperation between the second arc arm  212  and the second circular arc groove  2211  constitutes a virtual axis type connection, which can hide the connection structure between the rotating arm  22  and the base  10  inside the base  10  and make the foldable hinge more compact. 
     Since the axis m1 of the second circular arc groove  2211  is parallel to the axis m2 of the first arc arm  222 , a rotation axis of the support member  21  relative to the rotating arm  22  and a rotation axis of the rotating arm  22  relative to the base  10  are parallel. In a process of folding or unfolding the folding assembly  20 , the support member  21  and the rotating arm  22  as well as the rotating arm  22  and the base  10  can rotate smoothly, and there will be no obvious gap, improving the stability of the foldable hinge. 
     In some examples, the second circular arc groove  2211  may be a quarter arc, one-third arc, or the like; and the second arc arm  212  can be a quarter arc, one-third arc, or the like. A person skilled in the art can adapt specific parameters of the second arc arm  212  and the second circular arc groove  2211  to actual needs. 
     In an embodiment of the present disclosure, each of the first circular arc groove  11  and the first arc arm  222  is a quarter arc. 
     Referring again to  FIG.  3   , the surface of the base  10  also has a first recess  12  on a side of the first circular arc groove  11 , and a side wall of the first recess  12  has a pin shaft  13 . As shown in  FIG.  7   , the connection block  213  of the support member  21  is in the first recess  12  and the pin shaft  13  is in the first guiding sliding slot  2131 . 
     By mounting the connection block  213  in the first recess  12  and mounting the pin shaft  13  in the first guiding sliding slot  2131 , a rotational connection between the support member  21  and the base  10  can be realized; the support member  21  can be rotated at any angle relative to the base  10  during folding; and a connection structure of the connection block  213  and the first recess  12  can be hidden inside the base  10 , making the foldable hinge more compact. In a process of opening and closing the folding assemblies  20  relative to the base  10 , the pin shaft  13  slides in the first guiding sliding slot  2131 , enabling a sliding connection between the support member  21  and the base  10 . 
     When the folding assembly  20  is in the unfolded state, the connection block  213  is in the first recess  12  and the pin shaft  13  is at a first end of the first guiding sliding slot  2131  close to the support member  21 . In the process of bringing the folding assemblies  20  together, the connection block  213  rotates with the pin shaft  13  as a center, and the pin shaft  13  slides along the first guiding sliding slot  2131  toward a second end of the first guiding sliding slot  2131  away from the support member  21 . When the folding assemblies  20  are in the folded state, the pin shaft  13  is at the second end of the first guiding sliding slot  2131  away from the support member  21 . 
     As shown in  FIG.  7   , the first guiding sliding slot  2131  exhibits a circular arc shape, and the pin shaft  13  makes a circular arc movement relative to the support member  21  during rotation of the rotating arm  22 . 
     In this example, a cross-sectional shape of the pin shaft  13  is circular. In other examples, the cross-sectional shape of the pin shaft  13  may also be polygonal. 
     In this example, each of two opposing side walls of the first recess  12  has a pin shaft  13 , and two pins  13  are arranged coaxially. Each of two side walls of the connection block  213  have a first guiding sliding slot  2131 , and the two pins  13  slide in the two first guiding sliding slots  2131  correspondingly, which can make the sliding between the support members  21  and the base  10  more stable. 
     Referring to  FIGS.  6  and  7   , a portion  213   a  of the connection block  213  protrudes relative to a side edge of the first support plate  211  close to the base  10 , and the portion  213   a  of the connection block  213  has a support surface  2132 . The foldable hinge also includes a second support plate  30  between the two folding assemblies  20 , and the second support plate  30  is movably coupled to the base  10  and can move relative to the base  10  in a direction approaching or away from the base  10 . A direction of movement of the second support plate  30  is schematically illustrated with arrows in  FIG.  7   . 
       FIG.  8    is a schematic diagram showing a part of a folded hinge in an unfolded state in accordance with an embodiment of the present disclosure. The second support plate  30  is omitted in  FIG.  8   . When the two folding assemblies  20  are unfolded, the portion  213   a  of the connection block  213  is on a side of the second support plate  30  close to the base  10 , and the support surface  2132  is in contact with a surface of the second support plate  30  close to the base  10 . That is, the portion  213   a  of the connection block  213  moves to below the second support plate  30  and the support surface  2132  contacts a lower surface of the second support plate  30 , to hold the second support plate  30 . Referring to  FIG.  7   , the support surface  2132  is separated from the second support plate  30  when the two folding assemblies  20  are brought together. 
     When the two folding assemblies  20  are unfolded, the connection block  213  is in the first recess  12  and right below the second support plate  30 . A surface of the connection block  213  close to the second support plate  30  is in contact with the second support plate  30 , in which case the connection block  213  can support the second support plate  30  and hold up the second support plate  30 . In the process of bringing the two folding assemblies  20  together, along with the rotation of the support member  21 , the connection block  213  gradually rotates to a lateral side of the second support plate  30 , in which case the connection block  213  is separated from the second support plate  30 , and the second support plate  30  loses support and moves in the direction close to the base  10 , enlarging the drop-shaped receiving space formed when the folding assemblies  20  is in the folded state. 
       FIG.  9    is a schematic diagram showing a second support plate in accordance with an embodiment of the present disclosure. As shown in  FIG.  9   , the foldable hinge also includes an elastic member  41  and a connection bracket  42 , and the second support plate  30  is mounted on the base  10  by the elastic member  41  and the connection bracket  42 . 
       FIG.  10    is a schematic diagram showing that the second support plate and the base are assembled in accordance with an embodiment of the present disclosure. As shown in  FIG.  10   , a surface of the base  10  close to the second support plate  30  has a first mounting slot  14 , and a side wall of the first mounting slot  14  has a limiting recess  141 . The connection bracket  42  includes a second body portion  421  and a limiting portion  422 . The second body portion  421  is in the first mounting slot  14 . The limiting portion  422  is in the limiting recess  141 . The elastic member  41  is in the limiting recess  141 , and the elastic member  41  is between the limiting portion  422  and a side wall of the limiting recess  141 . The second body portion  421  is coupled to the second support plate  30 . 
     The elastic member  41  and the connection bracket  42  are provided so that the second support plate  30  can move in the direction close to the base  10  relative to the base  10  under an elastic force of the elastic member  41 . During the unfolding of the two folding assemblies  20 , the second support plate  30  moves in the direction away from the base  10  under the support of the connection block  213 , until the second support plate  30  is flush with the two first support plates  211 , in which case the second support plate  30  and the two first support plates  211  can spread the flexible screen flat. When the two folding assemblies  20  are folded, the second support plate  30  moves in the direction close to the base  10  under the action of the elastic member  41  until the second support plate  30  is in contact with the base  10 , which is conducive to increasing the receiving space enclosed by the second support plate  30  and the two first support plates  211 , reducing or avoiding extrusion and collision caused by the foldable hinge to a folding part of the flexible screen, and effectively protecting the folding part of the flexible screen. 
     The elastic member  41  is between the limiting portion  422  of the connection bracket  42  and the side wall of the limiting recess  141  and is in a compressed state. When the two folding assemblies  20  are unfolded, the connection block  213  contacts the second support plate  30 . Since the connection block  213  has a supporting effect on the second support plate  30 , the elastic force of the elastic member  41  on the limiting recess  141  is not sufficient to drive the connection bracket  42  and the second support plate  30  to move in the direction close to the base  10 , in which case the second support plate  30  is flush with the two first support plates  211 . Referring to  FIG.  7   , the first support plate  211  rotates relative to the base  10  when the two folding assemblies  20  are brought together, in which case the connection block  213  is separated from the second support plate  30 , and the second support plate  30  is in the first mounting slot  14 . 
     In some examples, the elastic member  41  is a spring. 
       FIG.  11    is a schematic diagram showing that a second support plate and a connection bracket are assembled in accordance with an embodiment of the present disclosure. As shown in  FIG.  11   , a surface of the second body portion  421  has a first through-hole  4211 , the second support plate  30  has a second through-hole  31 , the second through-hole  31  is opposite the first through-hole  4211 , and an inner side wall of the second through-hole  31  has a first thread  311 . The foldable hinge also includes a guide member  43 . An end of the guide member  43  close to the connection bracket  12  has a second thread  431 , and the guide member  43  is mounted in the first through-hole  4211  and the second through-hole  31 . The guide member  43  is fixedly coupled to the second support plate  30  by cooperation of the first thread  311  and the second thread  431 . 
     Referring to  FIG.  8   , the first mounting slot  14  has a guide hole  142  in a bottom of the first mounting slot, and the guide member  43  has a first end coupled to the connection bracket  42  and the second support plate  30  and a second end inserted in the guide hole  142 . The guide hole  142  is arranged in the bottom of the first mounting slot  14 , and the guide member  43  is in the guide hole  142  and is movable relative to the guide hole  142 , enabling the second support plate  30  to move more stably. 
       FIG.  12    is a partially exploded view of a foldable hinge in accordance with an embodiment of the present disclosure. At least the rotating arm  22  and the support member  21  are omitted in the figure. As shown in  FIG.  12   , the foldable hinge also includes a synchronization assembly  50 . The synchronization assembly  50  is in the base  10 , and the synchronization assembly  50  is coupled to the two folding assemblies  20 . Due to the arrangement of the synchronization assembly  50 , it is possible to synchronize the movement of the two folding assemblies  20 . 
     As shown in  FIG.  12   , the synchronization assembly  50  includes two synchronizing swing arms  51  extending to both sides of the base  10  correspondingly, and the two synchronizing swing arms  51  are transmissively coupled. Each synchronizing swing arm  51  has a first end rotatably coupled to the base  10  and a second end slidingly coupled to the first body portion  221 . 
     Referring to  FIG.  4   , the first body portion  221  of the rotating arm  22  has a second recess  2212  on a side wall of the first body portion close to the base  10 , and a side wall of the second recess  2212  has a second guiding sliding slot  2213 . Referring to  FIG.  12   , the second end of the synchronizing swing arm  51  away from the base  10  has a connection shaft  511 , and the connection shaft  511  is in the second guiding sliding slot  2213 . 
     The connection shaft  511  is mounted in the second guiding sliding slot  2213  to enable a sliding connection between the synchronizing swing arm  51  and the rotating arm  22 . The rotation axis of the rotating arm  22  is not coaxial with the synchronizing swing arm  51 . During rotation of the rotating arm  22 , the connection shaft  511  slides relative to the second guiding sliding slot  2213 , so that the rotating arm  22  can drive the synchronizing swing arm  51  to rotate, and the synchronizing swing arm  51  can drive the rotating arm  22  to rotate. 
       FIG.  13    is a schematic diagram showing a synchronizing swing arm in accordance with an embodiment of the present disclosure. As shown in  FIG.  13   , the synchronizing swing arm  51  includes a gear portion  512  and a third body portion  513 , and the gear portion  512  and the connection shaft  511  are at two ends of the third body portion  513 , correspondingly. 
     In some examples, the gear portions  512  of the two synchronizing swing arms  51  engage, so that the gear portions  512  of the two synchronizing swing arms  51  cooperate with each other to enable the two synchronizing swing arms  51  to rotate synchronously. 
     In an embodiment of the present disclosure, referring to  FIG.  12   , the synchronization assembly  50  also includes a plurality of synchronizing gears  52  that engage with each other, and the gear portions  512  of the two synchronizing swing arms  51  are transmissively coupled by the plurality of synchronizing gears  52 . During rotation of one synchronizing swing arm  51 , the other synchronizing swing arm  51  is driven by the transmission of the plurality of synchronous gears  52 , achieving synchronous rotation of the two synchronizing swing arms  51 . 
     As shown in  FIG.  12   , the foldable hinge further includes a plurality of mounting shafts  15  in the base  10 . A part of the mounting shafts  15  are inserted in the gear portions  512  and circumferentially limited by the gear portions  512 , and another part of the mounting shafts  15  are inserted in the synchronizing gears  52  and circumferentially limited by the synchronizing gears  52 . The foldable hinge further includes a plurality of damping rings  60  fitted over the plurality of mounting shafts  15  correspondingly. The damping rings  60  are in interference fit with the mounting shafts  15 , and the plurality of damping rings  60  are fixedly coupled to the base  10 . 
       FIG.  14    is a schematic diagram showing a mounting shaft in accordance with an embodiment of the present disclosure. As shown in  FIG.  14   , the mounting shaft  15  includes a friction segment  151  and a mounting segment  152 , and the friction segment  151  is at a first end of the mounting segment  152 . The mounting segment  152  has a snap slot  153  at a second end of the mounting segment  152  away from the friction segment  151 . The mounting segment  152  is used to cooperate with the gear portion  512  or the synchronizing gear  52 , which is fitted over the mounting segment  152 . 
     In some examples, the mounting segment  152  has a polygonal cross-section, and the mounting segment  152  is inserted into the gear portion  512  or the synchronizing gear  52  and can form circumferential limitation with the gear portion  512  or the synchronizing gear  52 . The mounting shaft  15  is circumferentially stationary relative to the gear portion  512  or the synchronizing gear  52  fitted over the mounting segment  152 , but can perform axial relative displacement. 
     As shown in  FIG.  12   , the side wall of the base  10  has a damping ring mounting hole  16 , and the damping ring  60  is fixedly mounted in the damping ring mounting hole  16 . The friction segment  151  of the mounting shaft  15  is mounted in the damping ring  60 . 
     As an example,  FIG.  15    is a schematic diagram showing a damping ring in accordance with an embodiment of the present disclosure. As shown in  FIG.  15   , the damping ring  60  includes a C-shaped segment  61  and a turnup segment  62 , and the cross-section of the damping ring  60  has an open ring structure overall to facilitate the installation of the friction segment  151  into the damping ring  60 . The C-shaped segment  61  is a columnar structure with a C-shaped cross-section, and the turnup segment  62  is coupled to both ends of the C-shaped segment  61 . The cross-sectional shape of the damping ring  60  matches the shape of the damping ring mounting hole  16 , and the turnup segment  62  is used to cooperate with the damping ring mounting hole  16  to limit the damping ring  60  and avoid the rotation of the damping ring  60 . The C-shaped segment  61  is fitted over the friction segment  151 . An outer diameter D1 of the friction segment  151  is greater than an inner diameter D2 of the C-shaped segment  61 , enabling the C-shaped segment  61  to form an interference fit with the friction segment  151 . 
     In some examples, the damping ring  60  may be a metal member, which has strong plasticity and is easy to bend into a corresponding shape. 
     During the rotation of the two folding assemblies  20 , the synchronizing swing arms  51  also rotate. Since the mounting shaft  15  is circumferentially limited by the gear portion  512 , the synchronizing swing arm  51  may drive the mounting shaft  15  to rotate, driving the mounting shaft  15  to rotate relative to the damping ring  60 . The outer diameter D1 of the friction segment  151  is larger than the inner diameter D2 of the C-shaped segment  61 , so that the damping ring  60  forms the interference fit with the friction segment  151  and the damping ring  16  grips the friction segment  151 . There is friction between an inner wall of the damping ring  60  and outer outer wall of the friction segment  151 , and the friction becomes resistance, preventing the rotation of the mounting shaft  15 . The friction between the damping ring  60  and the friction segment  151  allows the two folding assemblies  20  to remain in their current state without a sufficiently large external force for folding. Thus, the electronic device can hover at any angle within a range of angles at which it can be opened and closed. 
     Referring to  FIG.  12   , the foldable hinge also includes two self-locking plates  71 , a locking spring  72 , a spring stop  73 , a snap plate  74 , and an insertion tail plate  75 . Both self-locking plates  71  are fitted over the mounting segment  152  of the mounting shaft  15 , with one of the self-locking plates  71  abutting an end of the friction segment  151 . The gear portion  512  of the synchronizing swing arm  51  is fitted over the mounting segment  152  and is between the two self-locking plates  71 . The locking spring  72  and the spring stop  73  are sequentially fitted over the mounting segment  152 . The locking spring  72  is on a side of the two self-locking plates  71  away from the mounting segment  152  and abuts against one of the two self-locking plates  71  which is farther away from the mounting segment  152 . The spring stop  73  is at an end of the locking spring  72  away from the self-locking plate  71  and abuts against the locking spring  72 . The snap plate  74  is snapped at the snap slot  153 . 
     The foldable hinge also includes the insertion tail plate  75  coupled to the base  10 . The insertion tail plate  75  is at an end of the mounting shaft  15  away from the friction segment  151 . The insertion tail plate  75  is used to axially limit the mounting shaft  15  to prevent the mounting shaft  15  from coming out of the damping ring  60  under a spring force of the locking spring  72 . 
       FIG.  16    is a schematic diagram showing a self-locking plate in accordance with an embodiment of the present disclosure. As shown in  FIG.  16   , the self-locking plate  71  has a plurality of mounting holes  711 , and the mounting shafts  15  are coaxially inserted in the mounting holes  711  of the self-locking plate  71 , and the mounting shafts  15  and the self-locking plate  71  have a clearance fit. A side wall of the self-locking plate  71  close to the gear portion  512  also has a plurality of recesses  712  distributed circumferentially around the mounting holes  711 . Referring to  FIG.  13   , two ends of the gear portion  512  of the synchronizing swing arm  51  have a plurality of bosses  514 , and the plurality of bosses  514  are distributed circumferentially around the two ends of the gear portion  512 . The plurality of bosses  514  can engage with the plurality of recesses  712  to achieve cooperation between the synchronizing swing arm  51  with the two self-locking plates  71 . 
     In some examples, the synchronizing gear  52  may also have a plurality of bosses  514  at two ends of the synchronizing gear  52 , and the bosses  514  at the ends of the synchronizing gear  52  are fit in the corresponding recesses  712  around the mounting hole  711  in the self-locking plate  71 . 
     When the foldable hinge is in the unfolded state, the plurality of bosses  514  are within the plurality of recesses  712 . In a process of folding the foldable hinge, a sufficiently large external force is applied to perform the folding, so that the bosses  514  slide out of the recesses  712 , the locking spring  72  is compressed, and the two self-locking plates  71  move away from each other. Since one of the self-locking plates  71  abuts against the end of the friction segment  151  of the mounting shaft  15 , this self-locking plate  71  may drive the mounting shaft  15  to move axially when this self-locking plate  71  moves away from the gear portion  512  of the synchronous swing arm  51 , causing the mounting shaft  15  to move into the damping ring  60 . Since the snap plate  74  is snapped in the snap slot  153  of the mounting shaft  15 , the snap plate  74  is fixed relative to the mounting shaft  15 . When the mounting shaft  15  moves, the snap plate  74  squeezes the locking spring  72  through the spring stop  73 . The spring force of the locking spring  72  is equivalent to resistance, which hinders the rotation of the synchronous swing arm  51 . That is, the electronic device cannot be folded when the external force is not sufficient to overcome the spring force of the locking spring  72 , such that the foldable hinge can lock the electronic device in the unfolded state. 
     Similarly, when the foldable hinge is in the folded state, the plurality of bosses  514  are within the plurality of recesses  712 , such that the foldable hinge can lock the electronic device in the folded state. 
       FIG.  17    is a schematic diagram showing an electronic device in accordance with an embodiment of the present disclosure. As shown in  FIG.  17   , the electronic device includes two housings  100 , a flexible screen  200 , and a foldable hinge  300 . The two housings  100  are coupled to rotating arms  22  of the two folding assemblies  20  correspondingly, and the flexible screen  200  is coupled to the two housings  100 . 
     As shown in  FIG.  17   , two ends of the flexible screen  200  are coupled to the two housings  100  correspondingly. Since the foldable hinge is slidable the support member  21  relative to the base in the direction approaching and away from the base  10  during folding and unfolding, and the support member  21  is rotatably arranged on the rotating arm  22 , the support member  21  can perform sliding and rotating actions relative to the base  10  during folding and unfolding of the two housings  100 . Thus, during the folding and unfolding process, an action trajectory of the two support members  21  follow a folding and unfolding trajectory of the flexible screen  200 . When the two housings  100  are brought together, a distance between portions of two support members  21  coupled to the rotating arms  22  is smaller than a distance between portions of the two support members  21  coupled to the base  10 , and the two support members  21  and the base  10  enclose a drop-shaped receiving space. No squeeze, compression or damage will be produced on the flexible screen  200  when the flexible screen  200  is received in the drop-shaped receiving space. The drop-shaped receiving space is also conducive to the use effect and stability of the mobile terminal. 
       FIG.  18    is an exploded view of an electronic device in accordance with an embodiment of the present disclosure. As shown in  FIG.  18   , the housing  100  has a fixing hole  101  on a side of the housing  100  close to the rotating arm  22 . The two rotating arms  22  are fixedly coupled to the two housings  100  by screws, correspondingly. For example, as shown in  FIG.  18   , screws are installed into the connection holes  221   a  of the rotating arms  22  and the fixing holes  101  of the housing  100  to couple the rotating arms  22  to the housing  100 . 
     Only some embodiments of the present disclosure are described above and they are not intended to limit the present disclosure. Any modification, equivalent alternative, improvement, or the like made within the principles of the present disclosure shall be included in the protection scope of the present disclosure.