Patent Publication Number: US-2023163436-A1

Title: Electronic device

Description:
FIELD 
     The present disclosure relates to an electronic device including a battery pack. 
     BACKGROUND 
     Conventionally, an electronic device such as a smartphone incorporates a secondary battery represented by a lithium ion battery. For example, Patent Literature  1  discloses a battery cell in which a battery element is housed in an exterior material made of a laminate film, a resin layer is inserted into one or more surfaces of the battery element, and the battery element and the exterior material are separated from each other. For example, Patent Literature 2 discloses a battery pack including a battery cell including a battery element, at least one holder provided to face an end of the battery element, and an impact-absorbing structure formed in the holder. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2000-173641 A 
     Patent Literature 2: JP 2019-186016 A 
     SUMMARY 
     Technical Problem 
     In the above-described conventional technique, in an electronic device incorporating a battery pack, there is a possibility that the battery element itself is damaged by movement of the battery element inside the battery cell due to an impact such as dropping. 
     Therefore, the present disclosure proposes an electronic device capable of suppressing damage when a battery pack in which a battery element is movable is dropped. 
     Solution to Problem 
     To solve the problems described above, an electronic device according to an embodiment of the present disclosure includes: a battery pack that includes a battery cell housed inside an exterior member so that a battery element is movable in a movable direction; a housing that houses the battery pack; and adhesive members that bond the battery pack inside the housing, wherein the adhesive members bond the battery pack and the housing on a second line where an angle formed with a first line parallel to the movable direction is an acute angle and that passes through a center of the battery pack. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective diagram illustrating an appearance of a battery pack according to an embodiment. 
         FIG.  2    is an exploded perspective diagram of a battery pack according to an embodiment. 
         FIG.  3    is a diagram for illustrating a configuration example of a battery element configuring a battery cell according to an embodiment. 
         FIG.  4    is a schematic diagram illustrating an internal structure of an electronic device according to an embodiment. 
         FIG.  5    is a diagram illustrating a relationship between a battery pack and an adhesive member in an electronic device according to an embodiment. 
         FIG.  6    is a diagram for illustrating a principle of suppressing a drop impact energy in an electronic device according to an embodiment. 
         FIG.  7 A  is a diagram illustrating a fixing structure of a battery pack according to a comparative example. 
         FIG.  7 B  is a diagram illustrating a fixing structure of a battery pack according to a comparative example. 
         FIG.  7 C  is a diagram illustrating a fixing structure of a battery pack according to a comparative example. 
         FIG.  7 D  is a diagram illustrating a fixing structure of a battery pack according to a comparative example. 
         FIG.  8    is a diagram for illustrating a drop experiment method using a battery pack. 
         FIG.  9    is a diagram illustrating an experimental result when a battery pack fixed with a fixing structure of a comparative example is dropped. 
         FIG.  10    is a diagram illustrating an experimental result when a battery pack fixed with a fixing structure according to an embodiment is dropped. 
         FIG.  11    is a diagram illustrating a relationship between a battery pack and an adhesive member in an electronic device according to modification (1) of an embodiment. 
         FIG.  12    is a diagram illustrating a relationship between a battery pack and an adhesive member in an electronic device according to modification (2) of an embodiment. 
         FIG.  13    is an exploded perspective diagram illustrating another example of a battery pack according to an embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In each of the following embodiments, the same parts are denoted by the same reference numerals, and redundant description will be omitted. 
     A battery pack included in an electronic device according to the present embodiment includes, for example, a built-in battery pack that is not removable by a user. In the present embodiment, a structure including a battery element before the battery element is covered with a laminated sheet is referred to as a battery cell, and a structure in which a circuit board is coupled to the battery cell and a laminate sheet, a top holder, and a bottom holder are attached is referred to as a battery pack. In the battery pack and the battery cell, a lead-out side of a positive electrode terminal and a negative electrode terminal is referred to as a top portion, a side facing the top portion is referred to as a bottom portion, and the other sides are referred to as side portions. Furthermore, a length in a direction of both side portions may be referred to as a width, and a length in a direction of the top portion and the bottom portion may be referred to as a height. 
     Embodiment 
     Basic Configuration Example of Battery Pack According to Embodiment 
     An example of a basic configuration of a battery pack according to an embodiment will be described.  FIG.  1    is a perspective diagram illustrating an appearance of the battery pack according to the embodiment.  FIG.  2    is an exploded perspective diagram of the battery pack according to the embodiment. Hereinafter, in the drawings, an X axis indicates a width direction of the battery pack, a Y axis indicates a longitudinal direction of the battery pack, and a Z axis indicates a thickness direction of the battery pack, respectively. 
     A battery pack  10  illustrated in  FIGS.  1  and  2    is, for example, a battery pack of an angular or flat type lithium ion secondary battery. The battery pack  10  is mounted on a portable electronic device. In the present embodiment, the electronic device is configured so that the user cannot attach or detach the battery pack  10 . 
     Examples of the electronic device include, but are not limited to, a smartphone, a tablet computer, a notebook personal computer, a personal digital assistant (PDA), a portable game device, a display device, an electronic book, a music player, a navigation system, a machine tool, and the like. 
     As illustrated in  FIG.  2   , the battery pack  10  includes a battery cell  11 , a top holder  12 , a bottom holder  13 , a circuit board  14 , and a laminate sheet  15 . 
     The battery cell  11  includes, for example, a battery element electrically coupled to a circuit board covered with a laminate film of soft aluminum or the like. The laminate sheet  15  is attached to an outer periphery of the battery cell  11 . The battery cell  11  includes a battery element having a positive electrode terminal  24  and a negative electrode terminal  25 . The positive electrode terminal  24  and the negative electrode terminal  25  are covered with an insulating sheet (not illustrated) except for a coupling portion with the circuit board  14 . 
       FIG.  3    is a diagram for illustrating a configuration example of the battery element configuring the battery cell  11  according to the embodiment. As illustrated in  FIG.  3   , the battery cell  11  includes a battery element  20  and an exterior member  30 . 
     The battery element  20  is a secondary battery of a laminate film type. The battery element  20  includes, for example, a wound electrode body. The battery element  20  is housed in a film-like exterior member  30 . Note that  FIG.  3    illustrates a state of the battery element  20  before the battery element  20  is completely wound and a state of the exterior member  30  before the battery element  20  is housed inside, in order to make the configurations of the battery element  20  and the exterior member  30  easily viewable. 
     In the battery element  20 , for example, a positive electrode  21  and a negative electrode  22  are laminated with a separator  23  interposed therebetween, and the positive electrode  21  and the negative electrode  22  laminated with the separator  23  interposed therebetween are wound. The battery element  20  is impregnated with an electrolytic solution which is a liquid electrolyte. That is, the battery element  20  includes an electrolytic solution together with the positive electrode  21 , the negative electrode  22 , and the separator  23 . The positive electrode terminal  24  is attached to the positive electrode  21 . The negative electrode terminal  25  is attached to the negative electrode  22 . The outer peripheral portion of the battery element  20  is protected by, for example, a protective tape. The positive electrode terminal  24  and the negative electrode terminal  25  are led out from an inside to an outside of the exterior member  30 , for example. The positive electrode terminal  24  and the negative electrode terminal  25  are formed in a thin plate shape or a mesh shape by a conductive material. 
     The exterior member  30  is, for example, one sheet of film that can be folded in a direction of an arrow E indicated in  FIG.  3   . For example, a recess  31  for accommodating the battery element  20  is provided in a part of the exterior member  30 . The exterior member  30  is, for example, a laminate film or the like. The laminate film has, for example, a configuration such as a fusion layer, a metal layer, and a surface protective layer. 
     For example, in the exterior member  30 , the fusion layers are folded so as to face each other with the battery element  20  interposed therebetween, and then portions around the recess  31  in which the battery element  20  is accommodated are fused to each other, whereby the exterior member  30  is sealed in a state where the battery element  20  is housed in the recess  31 . The fusion layers of the exterior member  30  may be bonded to each other with an adhesive or the like interposed therebetween. 
     The exterior member  30  accommodates the battery element  20  in the recess  31  so that the battery element  20  is movable in a movable direction M (Y-axis direction) along an extending direction of the positive electrode terminal  24  and the negative electrode terminal  25  inside the recess  31 . That is, the recess  31  is formed in a size that enables movement of the housed battery element  20  in the movable direction M and does not allow movement of the battery pack  10  in the width direction (X-axis direction). The movable direction M is a direction in which the positive electrode terminal  24  and the negative electrode terminal  25  of the battery pack  10  are led out from the battery cell  11 . Between the exterior member  30  and the positive electrode terminal  24  and the negative electrode terminal  25 , for example, an adhesive film  26  for preventing outside air from entering the inside of the exterior member  30  is provided. 
     Returning to  FIG.  2   , the circuit board  14  is disposed on the top portion of the plate-shaped battery cell  11 , and is electrically coupled to the positive electrode terminal  24  and the negative electrode terminal  25  of the battery element  20 . The circuit board  14  is coupled to a flexible circuit board  16  coupled to a device body of the electronic device. As the circuit board  14 , for example, a coupling member such as a coupling terminal may be used instead of the flexible circuit board  16 . 
     The top holder  12  is attached to an end of the top portion of the battery cell  11 . For example, the top holder  12  is wrapped and fixed by the laminate sheet  15  together with the battery cell  11  in a state of being disposed at the end of the top portion of the battery cell  11 . The top holder  12  holds the circuit board  14  therein. The top holder  12  has an opening  21   a  at a position corresponding to the flexible circuit board  16  coupled to the circuit board  14 . The flexible circuit board  16  is led out to the outside of the battery pack  10  via an opening  12   a.    
     The bottom holder  13  is attached to an end of a bottom portion of the battery cell  11 . For example, the bottom holder  13  is wrapped and fixed by the laminate sheet  15  together with the battery cell  11  in a state of being disposed at the end of the bottom portion of the battery cell  11 . The bottom holder  13  is fixed to the battery cell  11  by an adhesive  17 . 
     Note that  FIG.  2    illustrates a simplified configuration of the top holder  12  and the bottom holder  13 , and the present disclosure is not limited to this configuration. 
     The laminate sheet  15  has a substantially rectangular shape, and is attached to the battery cell  11  so as to wrap the battery cell  11 . The laminate sheet  15  is attached to a periphery of the battery cell  11  via an adhesive. The laminate sheet  15  is a protective sheet for protecting the battery cell  11 , and may have higher strength than a resin laminate sheet. Thus, the battery pack  10  can protect the battery cell  11  from an external impact. The laminate sheet  15  may be, for example, a laminate in which an electrically insulating resin layer is laminated on both surfaces of a hard aluminum layer. 
     The configuration example of the battery pack  10  according to the embodiment has been described above. Note that the above-described configuration described with reference to  FIGS.  1  to  3    is merely an example, and the configuration of the battery pack  10  according to the present embodiment is not limited to such an example. The functional configuration of the battery pack  10  according to the present embodiment can be flexibly modified according to specifications and operations. The battery pack may have a configuration in which the battery element is housed inside the exterior member so as to be movable in the movable direction M. The battery pack may include, for example, a configuration in which the battery element is attached to the exterior member with a tape or a label. In addition, the movable direction M may include, for example, an assumed drop direction in the electronic device, a direction set in advance based on a disposition relationship between the battery pack and a board coupled to the battery pack, and the like. 
     Problems of Battery Pack 
     The battery pack  10  is fixed inside the electronic device by, for example, a double-sided tape, an adhesive, or the like. However, in the battery pack  10 , the battery element  20  is not fixed to the recess  31  of the exterior member  30  inside the battery cell  11 . Therefore, in a case where the electronic device is dropped, or the like, in the battery pack  10 , the battery element  20  may move in the movable direction M due to the impact. For example, in the battery pack  10 , when the battery element  20  moves, the positive electrode terminal  24  and the negative electrode terminal  25  may be broken, or the battery element  20  itself may be damaged. The present embodiment provides an electronic device in which the battery element  20  is movable thereby suppressing damage when the battery pack  10  is dropped. 
     Configuration Example of Electronic Device According to Embodiment 
       FIG.  4    is a schematic diagram illustrating an internal structure of the electronic device according to the embodiment.  FIG.  4    illustrates a state in which a back surface cover of the electronic device is seen through.  FIG.  4    illustrates only a configuration according to the present disclosure, and omits other configurations.  FIG.  5    is a diagram illustrating a relationship between the battery pack and the adhesive member in the electronic device according to the embodiment.  FIG.  6    is a diagram for illustrating a principle of suppressing the drop impact energy in the electronic device according to the embodiment. 
     In the example illustrated in  FIG.  4   , an electronic device  1  is a smartphone. The electronic device  1  includes the battery pack  10 , a housing  40 , and adhesive members  50 . 
     The electronic device  1  is housed inside the housing  40  so that a direction from a top portion  10 T to a bottom portion  10 B of the battery pack  10  is along the longitudinal direction (Y-axis direction) of electronic device  1 . The housing  40  is formed in a hollow thin plate shape by combining a front cover and a back surface cover, for example. The electronic device  1  houses the flexible circuit board  16 , which is a coupling portion of the battery pack  10 , in a state of being electrically coupled to a board  41  inside the housing  40 . The board  41  is housed inside the housing  40  and includes, for example, a board or the like that controls the electronic device  1 . 
     In the electronic device  1 , the battery pack  10  that is positioned at a predetermined position is fixed inside the housing  40  by the adhesive members  50 . In the electronic device  1 , the battery pack  10  is disposed inside the housing  40  so as to have an interval within a predetermined tolerance range with respect to components around the battery pack  10 . 
     As illustrated in  FIGS.  4  and  5   , the adhesive members  50  bond the battery pack  10  to the inside of the housing  40 . The adhesive members  50  include, for example, a double-sided tape, an adhesive, and the like. The adhesive members  50  fix the battery pack  10  to the housing  40  by bonding a component fixed to an inner surface of the housing  40  or an inside of the housing  40  and the laminate sheet  15  of the battery pack  10 . 
     The adhesive members  50  bond the battery pack  10  and the housing  40  at fixing positions P on a second line L 2  at which an angle θ formed with a first line L 1  parallel to the movable direction M of the battery element  20  is an acute angle and that passes through a center  10 S of the battery pack  10 . The fixing positions P are set, for example, to be in vicinities of corner portions  10 C that are the diagonals of the battery pack  10 . The corner portions  10 C according to the present disclosure are centered on a portion where two sides of the battery pack  10  are connected, and include partial regions of surfaces facing the housing  40 . The angle θ formed by the first line L 1  and the second line L 2  is an angle smaller than a right angle, and may be any angle. The center  10 S of the battery pack  10  includes, for example, a center of a contact surface of the laminate sheet  15  with the housing  40 , a range away from the center by a predetermined distance, or the like. Accordingly, when a slight impact is applied to the electronic device  1 , the adhesive members  50  prevent the position of the battery pack  10  from being displaced inside the electronic device  1 . That is, the adhesive members  50  have a strength capable of suppressing displacement between the battery pack  10  and the housing  40 . 
     In the examples illustrated in  FIGS.  4  and  5   , the second line L 2  is the diagonal line connecting the two corner portions  10 C of the battery pack  10 . The adhesive members  50  bond the battery pack  10  and the housing  40  at the fixing positions P of the two corner portions  10 C on the second line L 2 . The fixing positions P of the corner portions  10 C may be, for example, positions in the vicinities of the corner portions  10 C or positions away from the corner portions  10 C. Two corner portions  10 D of the battery pack  10  facing the corner portions  10 C with the first line L 1  interposed therebetween are not provided with the adhesive members  50 . That is, in the electronic device  1 , the portions of the corner portions  10 D of the battery pack  10  are not fixed to the housing  40 . In other words, in the battery pack  10 , the corner portions (second corner portions)  10 D facing the corner portions  10 C of the housing  40  to which the adhesive members  50  are bonded with the first line L 1  interposed therebetween are not bonded to the housing  40 . 
     The adhesive members  50  are formed in a band shape extending from the corner portions  10 C of the battery pack  10  to the vicinity of the first line L 1 . The adhesive members  50  fix the battery pack  10  and the housing  40  in a range from the fixing positions P of the corner portions  10 C of the battery pack  10  to the vicinity of the first line L 1 . Note that the adhesive members  50  may be realized by one band-shaped adhesive member or may be realized by a plurality of circular adhesive members. 
     For example, the adhesive members  50  are provided at fixing positions of the battery pack  10 , and the battery pack  10  is assembled to the housing  40  to fix the battery pack  10  and the housing  40 . The adhesive members  50  may be provided on any one of the battery pack  10  and the housing  40 , or may be provided on the housing  40  side. 
     The configuration example of the electronic device  1  according to the embodiment has been described above. Note that the above-described configuration described with reference to  FIG.  4    is merely an example, and the configuration of the electronic device  1  according to the present embodiment is not limited to such an example. The functional configuration of the electronic device  1  according to the present embodiment can be flexibly modified according to specifications and operations. 
     In the present embodiment, a case where the adhesive members  50  bond the battery pack  10  and the housing  40  at the fixing positions P of the two corner portions  10 C in the electronic device  1  will be described, but the present invention is not limited thereto. For example, the electronic device  1  may be configured to provide the adhesive members  50  at one or three or more fixing positions on the second line L 2 . For example, the electronic device  1  may have a configuration in which a circular adhesive member  50  is provided at one fixing position in the vicinity of the center  10 S of the battery pack  10  on the second line L 2 . 
     In the present embodiment, in the electronic device  1 , a case where the first line L 1  and the second line L 2  pass through the center  10 S of the battery pack  10  has been described, but the present invention is not limited thereto. For example, in the electronic device  1 , the first line L 1  may not pass through the center of the battery pack  10  as long as the first line L 1  is parallel to the movable direction M of the battery element  20 . 
     Operating Principle of Electronic Device According to Embodiment 
       FIG.  6    is a diagram for illustrating the principle of the battery pack  10  when an impact energy at the time of dropping is applied to the electronic device  1  according to the embodiment. In  FIG.  6   , only the battery pack  10  of the electronic device  1  is illustrated, and other configurations are omitted. 
     In the example illustrated in  FIG.  6   , the electronic device  1  is dropped onto a ground from the bottom portion  10 B side of the battery pack  10  in a drop direction F. In this case, when the impact due to the dropping is applied to the battery pack  10  via the electronic device  1 , a moment in the rotation direction R is generated, and the impact energy in the drop direction F can be released in the rotation direction R. That is, in the electronic device  1 , since the battery pack  10  and the housing  40  are fixed at the two corner portions  10 C on the second line L 2  and the battery pack  10  and the housing  40  are not fixed at the two corner portions  10 D, it is possible to generate the moment in the rotation direction R around the second line L 2 . As a result, the electronic device  1  can reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable. In addition, even when the battery pack  10  and the housing  40  are fixed at the two corner portions  10 C on the second line L 2  and the battery pack  10  and the housing  40  are fixed at one of the two corner portions  10 D, the electronic device  1  can generate the moment in the rotation direction R around the second line L 2 . 
     Comparison between Fixing Structure of Battery Pack According to Embodiment and Fixing Structure of Comparative Example 
     The fixing structure of a comparative example of the battery pack  10  has various fixing structures for the double-sided tape. Each of  FIGS.  7 A to  7 D  is a diagram illustrating a fixing structure of the battery pack  10  according to the comparative example. In the fixing structure illustrated in  FIG.  7 A , the battery pack  10  and the housing  40  are fixed by providing two band-shaped double-sided tapes  61  along respective vicinities of the top portion  10 T and the bottom portion  10 B of the battery pack  10 . In the fixing structure illustrated in  FIG.  7 B , the battery pack  10  and the housing  40  are fixed by providing two band-shaped double-sided tapes  62  from the top portion  10 T to the bottom portion  10 B of the battery pack  10  and along the vicinity of each edge of the battery pack  10 . The fixing structure illustrated in  FIG.  7 C  fixes the battery pack  10  and the housing  40  by providing a double-sided tape  63  on an entire surface of the laminate sheet  15  of the battery pack  10  facing the housing  40 . In the fixing structure illustrated in  FIG.  7 D , the battery pack  10  and the housing  40  are fixed by providing a double-sided tape  64  having a substantially ring shape on an entire surface of the laminate sheet  15  of the battery pack  10  facing the housing  40 . 
       FIG.  8    is a diagram for illustrating a drop experiment method using the battery pack  10 . The experimental method illustrated in  FIG.  8    illustrates an experimental method in which the battery pack  10  is fixed to an object  70  with a fixing structure of the comparative example or the fixing structure according to the embodiment, an acceleration sensor  80  is attached in the vicinity of the center of the battery pack  10 , and the object  70  is dropped in the drop direction F. This experimental method makes it possible to observe the impact energy generated in the battery pack  10  based on a detection result of the acceleration sensor  80 . In  FIG.  8   , the width direction of the battery pack  10  is the X-axis direction, the direction from the top portion  10 T to the bottom portion  10 B of the battery pack  10  is the Y-axis direction, and the thickness direction of the battery pack  10  is the Z-axis direction. 
       FIG.  9    is a diagram illustrating an experimental result when the battery pack  10  fixed by the fixing structure of the comparative example is dropped. In  FIG.  9   , a vertical axis indicates an acceleration in the X-axis direction and the Y-axis direction, and a horizontal axis indicates time. The graph illustrated in  FIG.  9    illustrates the experimental result when the battery pack  10  is fixed to the object  70  with the fixing structure illustrated in  FIG.  7 A  and dropped. The graph illustrated in  FIG.  9    indicates that the impact due to the dropping is occurred in the battery pack  10  at timet 1 . In  FIG.  9   , a graph G 11  in the X-axis direction changes around time t 1 , and a graph G 12  in the Y-axis direction changes more greatly than the graph G 11 . That is, the graph G 12  indicates that the impact energy due to the dropping is greatly received with respect to the Y-axis direction of the battery pack  10  fixed by the fixing structure of the comparative example. Note that the experimental results using the fixing methods illustrated in  FIGS.  7 B,  7 C, and  7 D  are similar to the experimental result illustrated in  FIG.  9   , and thus are omitted. 
       FIG.  10    is a diagram illustrating an experimental result when the battery pack  10  fixed with the fixing structure according to the embodiment is dropped. In  FIG.  10   , as in  FIG.  9   , a vertical axis indicates an acceleration in the X-axis direction and the Y-axis direction, and a horizontal axis indicates time. The graph illustrated in  FIG.  10    indicates the experimental result when the battery pack  10  is fixed to the object  70  with the fixing structure illustrated in  FIGS.  4  and  5    and the object  70  is dropped. The graph illustrated in  FIG.  10    indicates that the impact due to the dropping is occurred in the battery pack  10  at time t 2 . In  FIG.  10   , a graph G 21  in the X-axis direction changes near time t 2 , but intervals of amplitudes are wider than those of the graph G 11  illustrated in  FIG.  9   , indicating that the impact in the X-axis direction is dispersed. In  FIG.  10   , the graph G 22  in the Y-axis direction changes near time t 2 , but fluctuation is smaller than that of the graph G 12  illustrated in  FIG.  9   , indicating that the impact energy in the Y-axis direction is suppressed. 
     As described above, in the electronic device  1  according to the embodiment, the adhesive members  50  bond the battery pack  10  and the housing  40  on the second line L 2  at which the angle θ formed with the first line L 1  parallel to the movable direction M of the battery pack  10  is an acute angle and that passes through the center  10 S of the battery pack  10 . As a result, when the electronic device  1  is dropped in the drop direction F along the movable direction M, the impact energy can be suppressed in the battery pack  10  more than that in the fixing structure of the comparative example. On the other hand, when the fixing structure of the comparative example is used, in the battery pack  10 , since the four corner portions  10 C and  10 D are fixed with the same adhesive strength, the impact energy due to the dropping cannot be released. As a result, the electronic device  1  having the fixing structure according to the embodiment can reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable. 
     Modification (1) of Embodiment 
     In the electronic device  1  according to the above embodiment, the fixing positions P fixed by the adhesive members  50  can be changed. 
       FIG.  11    is a diagram illustrating a relationship between the battery pack  10  and the adhesive members  50  in electronic device  1  according to modification (1) of the embodiment. As illustrated in  FIG.  11   , the adhesive members  50  bond the battery pack  10  and the housing  40  at fixing positions P′ on the second line L 2  at which an angle formed with a first line parallel to the movable direction M of the battery element  20  is an acute angle and that passes through the center  10 S of the battery pack  10 . The fixing positions P′ are set, for example, so that the flexible circuit board  16  is led out to the outside and is in the vicinities of the corner portions  10 D that are the diagonals of the battery pack  10 . The angle θ formed by the first line L 1  and the second line L 2  is smaller than a right angle. 
     In the example illustrated in  FIG.  11   , the second line L 2  is the diagonal line connecting two corner portions  10 D of the battery pack  10 . The adhesive members  50  bond the battery pack  10  and the housing  40  at the fixing positions P′ of the two corner portions  10 D on the second line L 2 . The fixing positions P′ of the corner portions  10 D may be, for example, positions in the vicinities of the corner portions  10 D or positions away from the corner portions  10 D. Two corner portions  10 C of the battery pack  10  facing the corner portions  10 D with the first line L 1  interposed therebetween are not provided with the adhesive members  50 . That is, in the electronic device  1 , the portions of the corner portions  10 C of the battery pack  10  are not fixed to the housing  40 . In the example illustrated in  FIG.  11   , the corner portions  10 C correspond to the second corner portions. 
     The adhesive members  50  are provided in a band shape extending from the corner portions  10 D of the battery pack  10  to the vicinity of the first line L 1 . The adhesive members  50  fix the battery pack  10  and the housing  40  in a range from the fixing positions P′ of the corner portions  10 D of the battery pack  10  to the vicinity of the first line L 1 . Note that the adhesive members  50  may be realized by one band-shaped adhesive member or may be realized by interspersing a plurality of circular adhesive members. 
     In the electronic device  1  according to the modification (1) of the embodiment, in a case where the electronic device  1  is dropped onto the ground from the bottom portion  10 B side of the battery pack  10  in the drop direction F, when the impact due to the dropping is applied to the battery pack  10 , a moment in a rotation direction R′ is generated, and the impact energy in the drop direction F can be released in the rotation direction R′. That is, in the electronic device  1 , since the battery pack  10  and the housing  40  are fixed at the two corner portions  10 D on the second line L 2  and the battery pack  10  and the housing  40  are not fixed at the two corner portions  10 C, the moment in the rotation direction R′ is generated around the second line L 2 . As a result, the electronic device  1  can reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable, similarly to the embodiment. 
     Modification (2) of Embodiment 
     In the electronic device  1  according to the embodiment, fixing positions to be fixed by the adhesive members  50  can be added. 
       FIG.  12    is a diagram illustrating a relationship between the battery pack  10  and the adhesive members  50  in electronic device  1  according to modification (2) of the embodiment. As illustrated in  FIG.  12   , the adhesive members  50  bond the battery pack  10  and the housing  40  at the fixing positions P on the second line L 2  at which an angle θ formed with the first line L 1  parallel to the movable direction M of the battery element  20  is an acute angle and that passes through the center  10 S of the battery pack  10 . The fixing positions P are set, for example, to be in the vicinities of the corner portions  10 C that are the diagonals of the battery pack  10 . The angle θ formed by the first line L 1  and the second line L 2  is smaller than a right angle. 
     The electronic device  1  further includes second adhesive members  51  that bond the battery pack  10  and the housing  40  with a lower adhesive strength than that of the adhesive members  50  at the corner portions  10 D of the battery pack  10  facing the corner portions  10 C of the battery pack  10  with the first line L 1  interposed therebetween. That is, the electronic device  1  according to the modification (2) of the embodiment includes the battery pack  10 , the housing  40 , the adhesive members  50 , and the second adhesive members  51 . 
     In the example illustrated in  FIG.  12   , the second adhesive members  51  bond the battery pack  10  and the housing  40  at two fixing positions Ps on a third line L 3  at which an angle θ 1  formed with the first line L 1  is an acute angle and that passes through the center  10 S of the battery pack  10 . For example, the fixing positions Ps are set so as to be in the vicinities of the corner portions  10 D which are the diagonals of the battery pack  10 . The angle θ 1  formed by the first line L 1  and the third line L 3  is smaller than a right angle. By making the shape of the second adhesive members  51  smaller than that of the adhesive members  50 , the adhesive strength between the battery pack  10  and the housing  40  is made smaller than that of the adhesive members  50 . As the second adhesive members  51 , an adhesive member having lower adhesive strength than the adhesive members  50  may be used. 
     In the electronic device  1  according to the modification (2) of the embodiment, in a case where the electronic device  1  is dropped onto the ground from the bottom portion  10 B side of the battery pack  10  in the drop direction F, when an impact due to the dropping is applied to the battery pack  10 , a moment in a rotation direction R is generated, and an impact energy in the drop direction F can be released in the rotation direction R. That is, in the electronic device  1 , the battery pack  10  and the housing  40  are fixed at the two corner portions  10 C on the second line L 2 , and the battery pack  10  and the housing  40  are fixed at the two corner portions  10 D on the third line L 3 , but the adhesive strength of the two corner portions  10 D on the third line L 3  is lower than that of the corner portions  10 C. Therefore, in the electronic device  1 , the moment in the rotation direction R is generated around the second line L 2  in accordance with the impact of the dropping. As a result, the electronic device  1  can reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable, similarly to the embodiment. Furthermore, since the electronic device  1  further includes the second adhesive members  51 , the adhesive strength between the battery pack  10  and the housing  40  can be improved. 
     Note that the modification (1) and modification (2) of the exemplary embodiment may be applied to the electronic device  1  of another modification or combined with each other. 
     Although the preferred embodiment of the present disclosure have been described in detail with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field of the present disclosure can conceive various changes or modifications within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present disclosure. 
     Furthermore, the effects described in the present specification are merely illustrative or exemplary, and are not restrictive. That is, the technique according to the present disclosure can exhibit other effects obvious to those skilled in the art from the description of the present specification together with or instead of the above effects. 
     In the above embodiment, in the electronic device  1 , a case where the second line L 2  serving as a reference of the adhesive members  50  is the diagonal line of the battery pack  10  has been described, but the present invention is not limited thereto. For example, in the electronic device  1 , the second line L 2  may be set to pass through the edge near the corner portions  10 C shifted from the corner of the battery pack  10  in a range where the angle formed by the first line L 1  and the second line L 2  is an acute angle. 
     In the above embodiment, a case where the battery pack  10  having a rectangular outer shape is used has been described as the electronic device  1 , but the present invention is not limited thereto. For example, the electronic device  1  may use a battery pack having a polygonal outer shape, a circular outer shape, or the like. In this case, the electronic device  1  may set the fixing positions P of the adhesive members  50  based on the movable direction M of the battery pack  10 . 
     In the above embodiment, a case where the electronic device  1  uses the battery pack  10  has been described, but the configuration of the battery pack is not limited thereto. The electronic device  1  can use battery packs having various different configurations.  FIG.  13    is an exploded perspective diagram illustrating another example of the battery pack according to the embodiment. As illustrated in  FIG.  13   , a battery pack  100  includes a battery cell  11 , a top holder  12 , a circuit board  14 , and a label  101 . 
     The label  101  is formed of a protective member that protects the battery cell  11 , the top holder  12 , the circuit board  14 , and an insulating sheet  19 . The label  101  includes a plate-shaped base portion  102  and a frame  103  formed at an edge of the base portion  102 . The label  101  fixes the battery cell  11 , the top holder  12 , the circuit board  14 , and the insulating sheet  19  by being attached to the base portion  102 . In the present embodiment, the label  101  protects the battery cell  11  in a state where a part of the battery cell  11  is exposed, but the label  101  may be configured to cover the entire battery cell  11 . 
     The battery pack  100  is fixed inside the electronic device  1  similarly to the battery pack  10  described above. However, since the battery element  20  is not fixed to the exterior member  30  inside the battery cell  11 , there is a possibility that the battery element  20  moves in the movable direction M due to the impact such as dropping of the electronic device  1 , similarly to the battery pack  10 . 
     In the electronic device  1 , the battery pack  10  and the housing  40  are bonded by the adhesive members  50  on the second line L 2  which is parallel to the movable direction M of the battery pack  100  and at which an angle  0  formed with the first line L 1  of the battery pack  10  intersects at an acute angle. As a result, when the electronic device  1  is dropped in the drop direction F along the movable direction M, the impact energy in the battery pack  100  can be suppressed. As a result, the electronic device  1  having the fixing structure according to the embodiment can reduce a movement amount of the battery element  20  inside the battery pack  100  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  100  in which the battery element  20  is movable. 
     In the battery pack  100 , for example, various methods can be used as a method of attaching the label  101 . In the battery pack  100 , for example, a component surrounding the periphery of the battery cell  11  may also serve as a board holder. For example, the battery pack  100  may have a configuration in which an adhesive member such as a tape and a sheet is provided and fixed to four sides or the entire surface of the battery cell  11 . 
     The electronic device  1  may use a built-in battery pack including the battery cell  11  and the circuit board  14  but not including the top holder  12 . That is, the electronic device  1  according to the present embodiment can be configured to include built-in battery packs having various configurations that cannot be removed and replaced by the user and may cause the battery element  20  to move due to dropping of the electronic device  1  or the like. 
     Effects 
     The electronic device  1  includes the battery pack  10  having the battery cell  11  housed inside the exterior member  30  so that the battery element  20  is movable in the movable direction M, the housing  40  that houses the battery pack  10 , and the adhesive members  50  for bonding the battery pack  10  inside the housing  40 . The adhesive members  50  bond the battery pack  10  and the housing  40  on the second line L 2  at which the angle θ formed with the first line L 1  parallel to the movable direction M is an acute angle and that passes through the center  10 S of the battery pack  10 . 
     As a result, when the electronic device  1  is dropped in the movable direction M, a moment in the rotation direction R is generated when the impact due to the dropping is applied to the battery pack  10  via the housing  40 , and the impact energy in the drop direction F can be released in the rotation direction R. As a result, the electronic device  1  can reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable. 
     In the electronic device  1 , in the battery pack  10 , portions (regions) facing the fixing positions P where the adhesive members  50  are bonded to the housing  40  with the first line L 1  passing through the center  10 S of the battery pack  10  interposed therebetween are not bonded to the housing  40 . 
     As a result, in the electronic device  1 , since the battery pack  10  and the housing  40  are not fixed at the portions of the housing  40  facing the fixing positions P with the first line L 1  interposed therebetween, it is possible to efficiently generate the moment in the rotation direction R around the second line L 2 . As a result, the electronic device  1  can further reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable. 
     In the electronic device  1 , the adhesive members  50  bond the battery pack  10  and the housing  40  at least two points on the second line L 2 . 
     Accordingly, in the electronic device  1 , the battery pack  10  and the housing  40  can be bonded to each other at least two points on the second line L 2 . As a result, the electronic device  1  can suppress damage when the battery pack  10 , in which the battery element  20  is movable, is dropped while maintaining the adhesive strength between the battery pack  10  and the housing  40 . 
     In the electronic device  1 , the second line L 2  is a diagonal line of the battery pack  10  having a polygonal shape, and the adhesive members  50  bond the battery pack  10  and the housing  40  at the corner portions  10 C of the battery pack  10  on the second line L 2 . 
     As a result, the electronic device  1  can generate the moment in the rotation direction R about the diagonal line of the housing  40  as a moment in accordance with the dropping. As a result, the electronic device  1  can further reduce a movement amount of the battery element  20  inside the battery pack  10  in accordance with the dropping, so that it is possible to suppress damage at the time of the dropping of the battery pack  10  in which the battery element  20  is movable. 
     In the electronic device  1 , the adhesive members  50  are provided in a band shape extending from the corner portions  10 C of the battery pack  10  to the vicinity of the first line L 1 . 
     Accordingly, in the electronic device  1 , by providing the adhesive members  50  in a band shape, the adhesive strength between the battery pack  10  and the housing  40  can be improved. As a result, the electronic device  1  can prevent an installation position of the battery pack  10  from being displaced inside the housing  40  when the slight impact of the housing  40  is applied. 
     In the electronic device  1 , the movable direction M of the battery element  20  in the battery pack  10  is a direction in which the positive electrode terminal  24  and the negative electrode terminal  25  of the battery pack  10  are led out. 
     As a result, even when the electronic device  1  is dropped in the direction in which the positive electrode terminal  24  and the negative electrode terminal  25  of the battery pack  10  are led out, the moment in the rotation direction R is generated, so that the impact energy transmitted to the positive electrode terminal  24  and the negative electrode terminal  25  of the battery pack  10  can be suppressed. As a result, the electronic device  1  can suppress failure of the battery pack  10 , a connection failure with the board, and the like due to dropping. 
     The electronic device  1  further includes the second adhesive members  51  that bond the battery pack  10  and the housing  40  with a lower adhesive strength than that of the adhesive members  50  at the corner portions (second corner portions)  10 D of the battery pack  10  facing the corner portions  10 C of the battery pack  10  with the first line L 1  interposed therebetween. 
     As a result, in the electronic device  1 , the battery pack  10  and the housing  40  are fixed at the two corner portions  10 C on the second line L 2 , and the battery pack  10  and the housing  40  are fixed at the corner portions (second corner portions)  10 D facing the corner portions  10 C, but the adhesive strength of the corner portions  10 D can be made lower than that of the corner portions  10 C. As a result, in the electronic device  1 , since the moment in the rotation direction R is generated around the second line L 2  in accordance with the impact of dropping, it is possible to suppress damage at the time of dropping the battery pack  10  in which the battery element  20  is movable and to improve the adhesive strength between the battery pack  10  and the housing  40 . 
     Note that the following configurations also belong to the technical scope of the present disclosure. 
     (1) 
     An electronic device comprising: 
     a battery pack that includes a battery cell housed inside an exterior member so that a battery element is movable in a movable direction; 
     a housing that houses the battery pack; and 
     adhesive members that bond the battery pack inside the housing, 
     wherein the adhesive members bond the battery pack and the housing on a second line where an angle formed with a first line parallel to the movable direction is an acute angle and that passes through a center of the battery pack. 
     (2) 
     The electronic device according to (1), 
     wherein in the battery pack, portions facing fixing positions where the adhesive members are bonded to the housing with the first line that passes through the center of the battery pack interposed therebetween are not bonded to the housing. 
     (3) 
     The electronic device according to (1) or (2), 
     wherein the adhesive members bond the battery pack and the housing at least two points on the second line. 
     (4) 
     The electronic device according to any one of (1) to (3), 
     wherein the second line is a diagonal line of the battery pack having a polygonal shape, and 
     the adhesive members bond the battery pack and the housing at corner portions of the battery pack on the second line. 
     (5) 
     The electronic device according to (4), 
     wherein the adhesive members are provided in a band shape extending from the corner portions of the battery pack to vicinities of the first line. 
     (6) 
     The electronic device according to any one of (1) to (5), 
     wherein the movable direction is a direction in which a terminal of the battery pack is led out. 
     (7) 
     The electronic device according to (1), further comprising: 
     second adhesive members that bond the battery pack and the housing with a lower adhesive strength than that of the adhesive members, at second corner portions of the battery pack facing the corner portions of the battery pack with the first line interposed therebetween. 
     REFERENCE SIGNS LIST 
       1  electronic device 
       10  battery pack 
       10 C,  10 D corner portion 
       10 S center of battery pack 
       11  battery cell 
       12  top holder 
       13  bottom holder 
       14  circuit board 
       15  laminate sheet 
       20  battery element 
       30  exterior member 
       40  housing 
       50  adhesive member 
       51  second adhesive member 
     F drop direction 
     M movable direction 
     L 1  first line 
     L 2  second line 
     P fixing position