Patent Publication Number: US-2023164945-A1

Title: Image capturing apparatus

Description:
BACKGROUND 
     Field 
     The present disclosure relates to an image capturing apparatus that includes a heat dissipation structure for heat generated from a heat generating source. 
     Description of the Related Art 
     Recently, miniaturization and high density of components mounted inside electronic devices have become remarkable along with a demand for miniaturization of the devices. 
     Meanwhile, a demand for higher functionality of image capturing apparatuses, particularly higher performance of moving image functions, is increasing, and amounts of heat generated by those apparatuses tend to increase. 
     In a case where a moving image is captured in a high temperature environment, there is a high possibility that a rise in temperature inside an image capturing apparatus will cause mounted components to malfunction or deteriorate in performance, and eventually cause the image capturing apparatus to break down. 
     Thus, in a case where a heat dissipation amount by natural heat dissipation is not sufficient with respect to a heat generation amount of an image capturing apparatus, a heat dissipation structure that uses forced air cooling by a fan and a thermal conduction member is used. 
     Japanese Patent Application Laid-Open No. 2020-030393 discusses an apparatus that cools a movable image capturing element by connecting it to a thermal conduction member. 
     Recently, an image capturing apparatus that performs shake correction by moving an image capturing element in a direction orthogonal to an optical axis direction has become widely used in order to improve image quality. 
     The image capturing apparatus that performs the above-described shake correction is also required to have sufficient heat dissipation performance since the heat generated by the image capturing element may affect the image quality at the time of driving a shake correction mechanism and the time of continuous imaging and the time of moving image capturing. 
     However, in the apparatus discussed in the above-described Japanese Patent Application Laid-Open No. 2020-030393, the thermal conduction member is physically connected to the movable image capturing element and thus hinders an operation of the image capturing element. 
     SUMMARY 
     An exemplary embodiment of the present disclosure is directed to the provision of an image capturing apparatus that satisfies heat dissipation performance without hindering a movable image capturing element. 
     According to an aspect of the present disclosure, an image capturing apparatus includes an image capturing element configured to move within a movable range in a direction different from an optical axis direction, a first circuit board configured to mount the image capturing element on the first circuit board, a second circuit board configured to face the first circuit board, a first flexible board configured to electrically connect the first circuit board and the second circuit board, and a fan, wherein the first flexible board is bent in an area that overlaps with the movable range of the image capturing element in the optical axis direction, and wherein, in a case of being viewed from a direction orthogonal to an optical axis, an orientation of an exhaust opening of the fan is arranged toward an inner surface of a bending portion of the first flexible board closest to the first circuit board at a center position of the movable range of the image capturing element. 
     Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a digital camera according to the present disclosure. 
         FIGS.  2 A and  2 B , respectively, are a front exploded perspective view and a rear exploded perspective view of an image capturing element unit according to the present disclosure. 
         FIGS.  3 A and  3 B , respectively, are a rear view and a schematic rear view of the image capturing element unit and a heat dissipation fan according to the present disclosure. 
         FIG.  4    is a rear perspective view of an image capturing element unit and a heat dissipation fan according to a first exemplary embodiment of the present disclosure. 
         FIGS.  5 A,  5 B, and  5 C , respectively, are an A-A cross-sectional view, a B-B cross-sectional view, and a rear view of the image capturing element unit and the heat dissipation fan according to the first exemplary embodiment of the present disclosure. 
         FIGS.  6 A and  6 B  are respective development views of an image capturing power supply flexible board and an image capturing signal flexible board according to the first exemplary embodiment of the present disclosure. 
         FIG.  7 A  is a side view of the image capturing element unit according to the first exemplary embodiment of the present disclosure.  FIG.  7 B  is a schematic view of a path for an airflow generated by the heat dissipation fan according to the first exemplary embodiment of the present disclosure. 
         FIGS.  8 A and  8 B  are rear perspective views of an image capturing element unit and a heat dissipation fan according to a second exemplary embodiment of the present disclosure. 
         FIGS.  9 A,  9 B, and  9 C , respectively, are an A-A cross-sectional view, a B-B cross-sectional view, and a rear view of the image capturing element unit and the heat dissipation fan according to the second exemplary embodiment of the present disclosure. 
         FIG.  10    is a block diagram according to the present disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of a technique according to the present disclosure will be described in detail below with reference to the attached drawings. 
     However, components described below can be appropriately modified in their dimensions, materials, shapes, and relative layout considering configurations and various conditions of an apparatus to which the present disclosure is applied. 
     Thus, the exemplary embodiments described below are not intended to limit the scope of the present disclosure thereto. 
     Well-known techniques or publicly known technologies in the relevant technical field can be applied to a configuration and a process that are not particularly illustrated or described. In addition, redundant descriptions may be omitted. 
     In the drawings, the same or functionally similar elements are denoted by the same reference numerals. In  FIG.  5   , an optical axis direction, a longitudinal direction, and a transverse direction, respectively, are defined as a Z direction, an X direction, and a Y direction. 
     (Rear Exploded Perspective View of Digital Camera  100 ) 
       FIG.  1    is a rear exploded perspective view of a digital camera  100  as an image capturing apparatus according to the present disclosure. 
     As illustrated in  FIG.  1   , the digital camera  100  includes a mount unit  102   a , a rear cover  101 , a front base  102 , a top cover  103 , a bottom cover  104 , and the side cover  105 . 
     An image capturing element unit  106  that includes an image shake correction mechanism, a main board (also referred to as a second circuit board)  107 , a shutter  108 , a finder  109 , and a chassis  110  are arranged inside the digital camera  100 . 
     The image capturing element unit  106  is configured with a movable unit that includes an image capturing element  115  and a fixed unit and is arranged perpendicular to an optical axis. 
     The front base  102  is formed of, for example, a magnesium die cast or a resin and includes the mount unit  102   a  for mounting an interchangeable lens. 
     The main board  107  is configured with a multi-layer substrate, and electronic components are mounted on both sides thereof. The main board  107  is fixed to the front base  102  and the metal chassis  110  with screws. 
     On the main board  107 , a control integrated circuit (IC)  107   a  for controlling an image capturing signal, a connector  107   b  for a storage medium for storing an external storage medium, and an external communication terminal  107   c  for connecting a connection cable to an external apparatus are mounted. 
     The external communication terminal  107   c  is covered with a terminal cover  105   a.    
     The image capturing element unit  106  is a member which consumes particularly large power and generates a large amount of heat and of which temperature rise is sharp in the digital camera  100 . 
     A possible image capturing time length of the digital camera  100  is limited by an operation guarantee temperature of each member. In order to ensure the possible image capturing time length as long as possible, it is necessary to take a measure to release the heat of the image capturing element unit  106 , which is a heat generating source, so that the temperature does not exceed the operation guarantee temperature. 
     The image capturing element unit  106  is fixed to the front base  102  with the screws, and the heat of the image capturing element unit  106  is released to the front base  102 . 
     A heat dissipation fan  130  is arranged near the image capturing element unit  106  with its blowing direction perpendicular to the optical axis. A wind passes through a rear surface of the image capturing element unit  106 , which is the heat generating source, and prevents the image capturing element unit  106  from becoming locally hot (details will be described below). 
     According to the present exemplary embodiment, a centrifugal fan is used as the heat dissipation fan  130  as a blowing unit. However, the fan is not limited to this one and, for example, an axial flow fan or the like can be used as long as the purpose can be achieved. 
     Further, according to the present exemplary embodiment, the blowing direction of the heat dissipation fan  130  is arranged perpendicular to the optical axis. However, the arrangement is not limited to this one as long as the airflow from the heat dissipation fan  130  directly hits the image capturing element unit  106 , and the heat dissipation fan  130  may be arranged so that the blowing direction is not perpendicular to the optical axis. 
     The main board  107  is also one of the heat generating sources, and a heat dissipation effect can be provided to a plurality of the heat generating sources by arranging an exhaust opening  131  of the heat dissipation fan  130  so that the air is blown between the image capturing element unit  106  and the main board  107 . 
     However, the image capturing element unit  106  including a movable unit  114  has few heat dissipation routes, so that it is advantageous for heat dissipation to arrange the exhaust opening  131  of the heat dissipation fan  130  at a position closer to the image capturing element unit  106  than to the main board  107 . 
     (Description of Image Capturing Element Unit  106 ) 
     The image capturing element unit  106  is described in detail with reference to  FIGS.  2 A and  2 B .  FIG.  2 A and  2 B , respectively, are a front exploded perspective view and a rear exploded perspective view of the image capturing element unit  106 . 
     The movable unit  114  includes a coil unit  116  in which a coil and a Hall element for moving the image capturing element  115  are arranged and is held by a sensor holder  117 . 
     Three magnets  118  are held on a drive mechanism  113  side, and the movable unit  114  is attracted and held by the magnets  118 . 
     A ball (not illustrated) is included in a ball holding unit  117   a  provided to the sensor holder  117  between the movable unit  114  and the drive mechanism  113 . 
     The movable unit  114  can be moved by changing an amount of energization to the coil unit  116 . 
     Hand shake correction can be applied by moving the movable unit  114  in a direction of cancelling a shake of a main body of the digital camera  100 . 
     In the image capturing element  115 , a sensor chip (not illustrated) is bonded to an image capturing board (also referred to as a first circuit board)  115   a  on which an image capturing circuit is mounted and is electrically connected to the image capturing board  115   a  by wire bonding. 
     The image capturing element  115  and the sensor holder  117  are bonded and fixed to each other with an adhesive. 
     Elements  115   b  such as a capacitor, a resistor, and a regulator of the image capturing circuit are mounted on a rear surface of a sensor chip attachment surface of the image capturing board  115 a. 
     The image capturing element unit  106  and the main board  107  are electrically connected to each other using a flexible wiring board. 
     An image capturing signal flexible board (also referred to as a second flexible board)  111  is provided with wiring for an image capturing signal output from the image capturing element  115  and for a control signal necessary for driving the image capturing element  115 , and the signals are transmitted to the control IC  107   a  on the main board  107 . 
     An image capturing power supply flexible board (also referred to as a first flexible board)  112  is a flexible board that supplies power for driving the image capturing element  115 . An inter-board connector is used for connecting the image capturing board  115   a  and each flexible board. 
     (Rear View and Schematic Diagram of Heat Dissipation Fan  130  and Image Capturing Element Unit  106 ) 
       FIGS.  3 A and  3 B , respectively, are a rear view and a schematic diagram of the heat dissipation fan  130  and the image capturing element unit  106 . 
     Movement of the movable unit  114  of the image capturing element unit  106  and a positional relationship with respect to the heat dissipation fan  130  are described. 
     The movable unit  114  can move perpendicular to the optical axis in a movement range  114   a  illustrated in  FIG.  3 B . Further, in a case where the movable unit  114  moves, the movable unit  114  always exists in a range  114   b.    
     The range  114   b  is a range in which the movable unit  114  exists even if the movable unit  114  moves to any position in the movement range  114   a.    
     Next, arrangement of the heat dissipation fan  130  will be described. As described above, the heat dissipation fan  130  blows air so that the air passes through the rear surface of the image capturing element unit  106 . 
     The exhaust opening  131  of the heat dissipation fan  130  is oriented so that the air is blown to the range  114   b  in which the movable unit  114  always exists if the movable unit  114  moves. 
     An outline of a blowing direction  131   a  is indicated in  FIG.  3 B . Since the blowing direction  131   a  is within the range  114   a , the heat dissipation effect can be achieved regardless of a position of the movable unit  114 , which is the heat generating source of the image capturing element unit  106 . 
     Further, the heat dissipation fan  130  is not physically connected to the movable unit  114 , so that the heat dissipation effect can be produced without impairing a hand shake correction function by the movement. A center position of the movable unit  114  matches the optical axis. 
     The airflow is exhausted from the exhaust opening  131  of the heat dissipation fan  130  in the transverse direction of the image capturing element  115 . 
     (Positional Relationship among Image Capturing Signal Flexible Board  111 , Image Capturing Power Supply Flexible Board  112 , and Heat Dissipation Fan  130 ) 
     A positional relationship among the image capturing signal flexible board  111 , the image capturing power supply flexible board  112 , and the heat dissipation fan  130  is described in detail with reference to  FIGS.  4  and  5 A to  5 C . 
       FIG.  4    illustrates the image capturing element unit  106  and the heat dissipation fan  130  viewed obliquely from the rear side of the digital camera  100 . 
     As illustrated in  FIG.  4   , the image capturing power supply flexible board  112  and the image capturing signal flexible board  111  are provided so as to fixed to the movable unit  114  and the drive mechanism  113  in the image capturing element unit  106 . 
       FIG.  5 C  is a rear view of the image capturing element unit  106 , and  FIGS.  5 A and  5 B , respectively, are an A-A cross-sectional view and a B-B cross-sectional view of  FIG.  5 C . 
     As illustrated in  FIG.  5 A , the image capturing power supply flexible board  112  is connected to a connector mounted on a surface on which the element  115   b  of the image capturing board  115   a  is mounted and has a first end portion  112   a  that is arranged in a direction substantially parallel to the image capturing board  115 a. 
     The image capturing power supply flexible board  112  further has a bending portion  112   b  that can be bent 180° from the first end portion  112   a  with a predetermined bending diameter and a surplus portion  112   c  that forms a portion from the bending portion  112   b  to a fixing portion  112   d  for fixing the image capturing power supply flexible board  112  to the drive mechanism  113 . 
     A second end portion  112   e  ahead of the fixing portion  112   d  is connected to the main board  107 . 
     With this configuration, it is assumed that the movable unit  114  of the image capturing element unit  106  is driven for hand shake correction. 
     Even so, the bending portion  112   b  and the surplus portion  112   c  absorb deformation of the image capturing power supply flexible board  112  and reduce an effect of tension of the image capturing power supply flexible board  112  on control of the movable unit  114 . 
     In addition, the bending portion  112   b  of the image capturing power supply flexible board  112  is formed at a portion extending from the first end portion  112   a  in a direction opposite to the heat dissipation fan  130 . 
     Thus, as illustrated in the A-A cross-sectional view in  FIG.  5 A , a space sandwiched between the image capturing board  115   a  and the surplus portion  112   c  of the image capturing power supply flexible board  112  is formed in an area of the image capturing board  115   a  near the heat dissipation fan  130  up to the bending portion  112   b.    
     Further, the image capturing power supply flexible board  112  is arranged to be at least partly included in an area in the blowing direction  131   a  of the heat dissipation fan  130  even if the movable unit  114  moves as illustrated in  FIG.  5 C . 
     With this configuration, even if the movable unit  114  moves, a gap can be formed between the image capturing power supply flexible board  112  and the image capturing board  115   a  in the area near the exhaust opening  131  on the image capturing board  115   a , and ventilation resistance of the airflow from the heat dissipation fan  130  can be reduced. 
     Accordingly, it is possible to prevent the image capturing power supply flexible board  112  from hindering the airflow and making it difficult for the air on the image capturing board  115   a  to move. 
     As illustrated in  FIG.  5 C , a horizontal direction and a vertical direction viewed from the rear side of the digital camera  100 , respectively, are defined as the X direction and the Y direction. 
     At that time, the three magnets  118  provided in the drive mechanism  113  are divided into a rectangular X direction magnet  118   a  and rectangular Y direction magnets  118   b  and  118   c  based on the respective directions in which the driving force is generated. 
     The Y direction magnet  118   b  is arranged closer to the X direction magnet  118   a  than the Y direction magnet  118   c.    
     In a case where the image capturing element unit  106  is viewed from the rear side of the digital camera  100  in the optical axis direction, an area that is sandwiched between a center  115   c  of the image capturing element  115  and the X direction magnet  118   a  and between the center  115   c  of the image capturing element  115  and the Y direction magnet  118   b  is defined as an area  140 . 
     The bending portion  112   b  of the image capturing power supply flexible board  112  is formed to be arranged in the area  140 . 
     With this configuration, an inner peripheral surface of the bending portion  112   b  receives a force from the airflow of the heat dissipation fan  130  near a place where the magnetic force for driving the movable unit  114  is generated, and thus it is possible to reduce an effect of disturbance that the movable unit  114  receives from the airflow. 
     In other words, it is possible to reduce a current to be applied to the coil unit  116  in order to cancel rotation moment to the movable unit  114  generated by the force received by the image capturing power supply flexible board  112  from the airflow. 
     In addition, it is possible to maintain controllability of the movable unit  114  compared with a case where the heat dissipation fan  130  is not driven. 
     The image capturing signal flexible board  111  and the image capturing power supply flexible board  112  are arranged in the longitudinal direction of the image capturing element  115 . 
     A feature of the bending portion  112   b  is described with reference to  FIGS.  7 A and  7 B .  FIG.  7 A  illustrates the image capturing element unit  106  viewed from the horizontal direction of the digital camera  100 . 
       FIG.  7 B  is a C-C cross-sectional view taken along a line C-C in  FIG.  7 A . 
     The bending portion  112   b  is formed so that a line segment  141  connecting the center of the exhaust opening  131  of the heat dissipation fan  130  and the center of the bending portion  112   b  does not match a normal line  142  of an inner surface (an inner peripheral surface) of the bending portion  112   b.    
     At that time, the normal line  142  of the inner surface (the inner peripheral surface) of the bending portion  112   b  is inclined toward the center  115   c  of the image capturing element  115  with respect to the line segment  141 . 
     More specifically, the bending portion  112   b  is formed to guide the airflow from the heat dissipation fan  130  in a direction toward the center  115   c  of the image capturing element  115  and to prevent the airflow from escaping in a direction toward the X direction magnet  118   a.    
     If the airflow escapes in the direction toward the X direction magnet  118   a , the airflow does not sufficiently spread over a wider range on the image capturing board  115 a, and the heat dissipation effect is impaired. However, the configuration of the present exemplary embodiment works towards preventing such an issue. 
     (Development View of Image Capturing Power Supply Flexible Board  112 ) 
       FIG.  6 A  illustrates a developed image capturing power supply flexible board  112 , and the first end portion  112   a  and the surplus portion  112   c  are formed at a certain angle so as not to be on a straight line across the bending portion  112   b.    
     With this configuration, in a case where the bending portion  112   b  is formed so that the line segment  141  and the normal line  142  do not match with each other, the image capturing power supply flexible board  112  can be accommodated within a small projection area viewed from the optical axis direction of the digital camera  100  as illustrated in  FIG.  5 C , and space efficiency is good. 
     The image capturing signal flexible board  111  has a bending configuration similar to that of the image capturing power supply flexible board  112  so that its tension does not affect the control of the movable unit  114  as possible. 
     However, as illustrated in  FIG.  4   , the image capturing signal flexible board  111  is oriented 180° opposite to the image capturing power supply flexible board  112 . 
     Further, a gap between a surplus portion  111   c  of the image capturing signal flexible board  111  and the image capturing board  115   a  is set wider than the gap between the surplus portion  112   c  of the image capturing power supply flexible board  112  and the image capturing board  115   a  and is configured to reduce the ventilation resistance. 
     A bending portion  111   b  of the image capturing signal flexible board  111  is formed in a direction facing the bending portion  112   b  of the image capturing power supply flexible board  112 . 
       FIG.  6 B  illustrates a developed image capturing signal flexible board  111 , and a first end portion  111   a  and the surplus portion  111   c  are formed at a certain angle across the bending portion  111   b.    
     (Movement of Airflow Generated by Heat Dissipation Fan  130 ) 
     Movement of the airflow generated by the heat dissipation fan  130  is described step by step with reference to  FIGS.  7 A and  7 B . 
     As indicated by arrows in  FIG.  7 B , the airflow from the heat dissipation fan  130  is exhausted from the exhaust opening  131 . 
     Then, the airflow passes through a space sandwiched between the image capturing board  115   a  and the surplus portion  112   c  and a space sandwiched between the first end portion  112   a  and the surplus portion  112   c  and reaches the inner periphery side of the bending portion  112   b.    
     At that time, the air on the image capturing board  115   a , to which heat is transferred from the image capturing board  115   a , is moved along the arrows in  FIG.  7 B  by the airflow from the heat dissipation fan  130 . 
     A direction of the airflow reaching the bending portion  112   b  is bent toward the center  115   c  of the image capturing element  115 , and the airflow is guided to the space sandwiched between the surplus portion  111   c  of the image capturing signal flexible board  111  and the image capturing board  115   a.    
     A part of the airflow reaches the bending portion  111   b  of the image capturing signal flexible board  111 , applies a force thereto, and partially cancels out the rotation moment applied to the movable unit  114  by the airflow at the bending portion  112 b. 
     The other part of the airflow passes through in the horizontal direction in  FIG.  7 B  viewed from the optical axis direction, moves and diffuses the heated air on the image capturing board  115   a  into the digital camera  100 . 
     The bending portion  112   b  of the image capturing power supply flexible board  112  and the bending portion  111   b  of the image capturing signal flexible board  111  are configured as described above. 
     Accordingly, the airflow from the heat dissipation fan  130  can be guided over the wide range on the image capturing board  115   a  and efficiently suppress a temperature rise of the image capturing element  115 . 
     In addition, the heat dissipation fan  130  itself is not physically connected to the movable unit  114  and thus can produce the heat dissipation effect without impairing the hand shake correction function by the movement. 
     According to the first exemplary embodiment, for example, the heat dissipation fan  130  is in a state of operating at a wind speed of 4.5 L/min. 
     A “liter per minute” (L/min) is a unit of a volumetric flow rate. The heat dissipation fan  130  is incorporated, and thus the maximum achievable temperature of the image capturing element unit  106  can be lowered by 10° C. 
     Accordingly, the temperature rise of the heat generating source is suppressed, and the digital camera  100  is less likely to reach a limit temperature at which it stops functioning due to heat generation. 
     The features of the present exemplary embodiment will be described below. 
     The image capturing apparatus includes the image capturing element  115  that can move within the movable range in a direction different from the optical axis direction, the first circuit board  115   a  on which the image capturing element  115  is mounted, and the second circuit board  107  facing the first circuit board  115   a.    
     The image capturing apparatus further includes the first flexible board  112  that electrically connects the first circuit board  115   a  and the second circuit board  107  and the heat dissipation fan  130 . 
     The first flexible board  112  is bent in an area overlapping the movable range of the image capturing element  115  in the optical axis direction. 
     If viewed from a direction orthogonal to the optical axis, an orientation of the exhaust opening  131  of the heat dissipation fan  130  is arranged toward an inner surface of the bending portion  112   b  of the first flexible board  112  closest to the first circuit board  115   a  at a center position of the movable range of the image capturing element  115 . 
     The next feature is that there is always an airflow path even at a mechanical end. 
     If viewed from the direction orthogonal to the optical axis, the inner surface of the bending portion  112   b  of the first flexible board  112  closest to the first circuit board  115   a  is always at least partly arranged in an area extending in the blowing direction  131   a  of the exhaust opening  131  of the heat dissipation fan  130  in a case where the image capturing element  115  moves in the movable range. 
     The next feature is that the bending portion does not form an orthogonal angle. 
     If viewed from the optical axis direction, in a case where a line segment connecting the center of the exhaust opening  131  and the center of the inner surface of the closest bending portion is defined, the line segment does not match the normal line of the inner surface of the bending portion. 
     The next feature is that the airflow does not blow on the magnets  118 . 
     If viewed from the optical axis direction, the normal line of the inner surface of the bending portion  112   b  of the first flexible board  112  closest to the first circuit board  115   a  is inclined toward the center  115   c  of the image capturing element  115  from the line segment. 
     The next feature is that a bending angle is not orthogonal if the flexible board is developed. 
     If viewed from the optical axis direction, in a case where the first flexible board  112  is developed, the first flexible board  112  is formed with an angle with which the first flexible board is not on a straight line at the bending portion closest to the first circuit board  115   a.    
     The next feature is that the image capturing apparatus is less affected by the rotation moment (it receives the airflow at a location where the effect of the rotation moment is reduced). 
     The image capturing apparatus includes a first magnet for driving the image capturing element  115  in a first direction among directions different from the optical axis direction and a second magnet for driving the image capturing element  115  in a second direction different from the first direction among the directions different from the optical axis direction. 
     Further, if viewed from the optical axis direction, the bending portion  112   b  of the first flexible board  112  is arranged in an area that is sandwiched between the center  115   c  of the image capturing element  115  and the first magnet and is sandwiched between the center  115   c  of the image capturing element  115  and the second magnet. 
     The next feature is that the image capturing apparatus cancels out the effect of the rotation moment, and the inner surfaces of the bending portions face each other. 
     The image capturing apparatus includes the second flexible board  111  that electrically connects the first circuit board  115   a  and the second circuit board  107 . 
     The second flexible board  111  is bent in the area overlapping the movable range of the image capturing element  115  in the optical axis direction. 
     Further, the inner surface of the bending portion  111   b  of the second flexible board  111  closest to the first circuit board  115   a  is formed to face the inner surface of the bending portion  112   b  of the first flexible board  112  closest to the first circuit board  115   a.    
     The next feature is that the blowing direction is the longitudinal direction of the image capturing element  115 , and a bending direction is the transverse direction of the image capturing element  115 . 
     The next feature is that the first flexible board  112  is made of a flexible board or a graphite sheet. 
     A second exemplary embodiment of the present disclosure is described with reference to  FIGS.  8 A,  8 B, and  9 A to  9 C . For the sake of simplicity, descriptions of parts overlapping with the first exemplary embodiment are omitted, and only different parts are described. 
       FIG.  8 A  illustrates the image capturing element unit  106  and the heat dissipation fan  130  viewed obliquely from the rear side of the digital camera  100 .  FIG.  8 B  is a diagram in which the image capturing signal flexible board  111  and the image capturing power supply flexible board  112  are hidden from  FIG.  8 A  for ease of viewing the drawing. 
     As illustrated in  FIGS.  8 A and  8 B , the image capturing element unit  106  is provided with graphite sheets  121  and  122  to be fixed to the movable unit  114  and the drive mechanism  113  so as to overlap with the image capturing power supply flexible board  112  and the image capturing signal flexible board  111 . 
     The graphite sheets  121  and  122  function as a heat dissipation member that transmits heat generated in the movable unit  114  to the drive mechanism  113  and that has flexibility which does not easily affect the controllability of the movable unit  114 . 
       FIG.  9 C  is a rear view of the image capturing element unit  106 , and  FIGS.  9 A and  9 B , respectively, are an A-A cross-sectional view and a B-B cross-sectional view of  FIG.  9 C . 
     As illustrated in  FIG.  9 A , the graphite sheet  122  has a first end portion  122   a  that is mounted to be in contact with the element  115   b  on the image capturing board  115   a  and is arranged in a substantially parallel direction to the image capturing board  115   a  therefrom. 
     The graphite sheet  122  further has a bending portion  122   b  that is bent 180° from the first end portion  122   a  with a predetermined bending diameter and a surplus portion  122   c  that forms a portion from the bending portion  122   b  to a fixing portion  122   d  for fixing the graphite sheet  122  to the drive mechanism  113 . 
     With this configuration, it is assumed that the movable unit  114  of the image capturing element unit  106  is driven for the hand shake correction. 
     Even so, the bending portion  122   b  and the surplus portion  122   c  absorb deformation of the graphite sheet  122  and reduce an effect of tension of the graphite sheet  122  on the control of the movable unit  114 . 
     In addition, the bending portion  122   b  of the graphite sheet  122  is formed at a portion extending from the first end portion  122   a  in the direction opposite to the heat dissipation fan  130 . 
     Thus, as illustrated in the A-A cross-sectional view in  FIG.  9 A , a space sandwiched between the image capturing board  115   a  and the surplus portion  122   c  of the graphite sheet  122  is formed in an area of the image capturing board  115   a  near the heat dissipation fan  130  up to the bending portion  122   b.    
     As illustrated in  FIG.  9 A , the image capturing power supply flexible board  112  is arranged so that the inner surface of the bending portion  112   b  of the image capturing power supply flexible board  112  faces an outer surface of the bending portion  122   b  of the graphite sheet  122 . 
     The graphite sheet  121  has a bending configuration similar to that of the graphite sheet  122  so that its tension does not affect the control of the movable unit  114  as possible. 
     However, as illustrated in  FIG.  8 B , the graphite sheet  121  is oriented 180° opposite to the graphite sheet  122 . 
     As illustrated in  FIG.  9 B , the image capturing signal flexible board  111  is arranged so that the inner surface of the bending portion  111   b  of the image capturing signal flexible board  111  faces an outer surface of a bending portion  121   b  of the graphite sheet  121 . 
     With this arrangement, fixing portions  121   d  and  122   d  of the graphite sheets  121  and  122  do not sandwich the image capturing signal flexible board  111  or the image capturing power supply flexible board  112 . 
     The fixing portions  121   d  and  122   d  of the graphite sheets  121  and  122  can be directly brought into contact with and fixed to the drive mechanism  113  and thus are desirable to the heat dissipation performance from the movable unit  114  to the drive mechanism  113 . 
     In addition, the configurations of the bending portions  121   b  and  122   b  of the graphite sheets  121  and  122  can be replaced with the bending portions  111   b  and  112   b  of the image capturing signal flexible board  111  and the image capturing power supply flexible board  112  according to the first exemplary embodiment. 
     Accordingly, it is clear that the second exemplary embodiment can obtain an effect similar to that of the first exemplary embodiment. 
     (Block Diagram Illustrating Configuration Example of Digital Camera  400 ) 
       FIG.  10    is a block diagram illustrating a configuration example of a digital camera  400  according to the present disclosure. 
     A shutter  410  is a focal-plane shutter that can freely control an exposure time of an image capturing unit  411  described below. 
     The control of the shutter  410  is performed by a system control unit  420  described below. 
     The image capturing unit  411  is an image capturing device that has an imaging plane on which an object image (an optical image) passing through a lens  501  is formed and outputs an electrical signal (an analog signal) corresponding to the optical image on the imaging plane by photoelectric conversion. 
     As the image capturing unit  411 , a charge couple device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor is used. 
     An analog-to-digital (A/D) converter  412  is a signal conversion unit that is used to convert an analog signal output from the image capturing unit  411  into a digital signal. 
     An image processing unit  413  is an image calculation unit that generates image data by performing predetermined pixel interpolation, resizing processing such as reduction, and color conversion processing on the digital signal from the A/D converter  412  or the digital signal from a memory control unit  422  described below. 
     The system control unit  420  controls a diaphragm position and a lens position based on a calculation result obtained from the image processing unit  413 . 
     The image processing unit  413  further performs calculation processing using the above-described image data and performs through the lens (TTL) type automatic white balance (AWB) processing based on the obtained calculation result. 
     The system control unit  420  is a control unit that includes at least one processor or circuit and controls the entire digital camera  400 . 
     The system control unit  420  executes a program stored in a nonvolatile memory  423 , which is described below, and thus realizes each process according to the present disclosure. 
     A memory  421  is a storage unit that temporarily stores the digital signal obtained by the image capturing unit  411  and converted by the A/D converter  412  and the image data generated by the above-descried image processing unit  413 . 
     The memory  421  has a storage capacity sufficient to store a predetermined number of still images, moving images of a predetermined time length, and sound. 
     The memory control unit  422  is a memory control unit that controls transmission and reception of data controlled by the system control unit  420  to and from the A/D converter  412 , the image processing unit  413 , and the memory  421 . 
     The digital signal output from the A/D converter  412  is directly written to the memory  421  via the image processing unit  413  and the memory control unit  422  or only via the memory control unit  422 . 
     The nonvolatile memory  423  is an electrically erasable/recordable read-only storage unit and stores a constant, a program, and the like for an operation of the system control unit  420 . 
     A system memory  424  is a readable and writable storage unit that stores a constant and a variable for the operation of the system control unit  420 , a program read from the nonvolatile memory  423 , and the like. 
     A system timer  425  is a time measurement unit that measures a time until auto power off for turning off various display members, which are described below, is executed and an exposure time. 
     The auto power off has a function of turning off the various display members, which are described below, in order to prevent battery consumption in a case where it is determined that a photographer does not operate the digital camera  400 . 
     A power supply unit  430  includes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a nickel-cadmium (NiCd) battery, a nickel-metal hydride (NiMH) battery, or a lithium ion (Li) battery, and an alternate current (AC) adapter. 
     A power supply control unit  431  includes a circuit for detecting the power supply unit  430 , which is the power supply for driving the digital camera  400 , a direct current to direct current (DC-DC) converter, and a switch circuit for switching a power supply destination. 
     The power supply unit  430  detects whether the battery is installed, a type of the battery, and a battery remaining amount. 
     Further, the power supply control unit  431  controls the DC-DC converter based on the detection result and an instruction from the system control unit  420  and supplies a required voltage to the supply destination at a required timing. 
     A communication terminal  440  is provided in the digital camera  400  and is electrically connected to a lens communication terminal  506  described below. 
     The communication terminal  440  is electrically connected, and thus the system control unit  420  that controls the entire digital camera  400  can communicate with a lens unit  500  described below. 
     A storage medium interface (I/F)  441  is an interface with a storage medium  600  described below. 
     An orientation detection unit  442  detects an orientation of the digital camera  400  with respect to the direction of gravity. 
     The orientation detection unit  442  can output orientation information as to whether an image captured by the image capturing unit  411  is an image captured with the digital camera  400  horizontally held or an image captured with the digital camera  400  vertically held based on the detected orientation. 
     The system control unit  420  can add the orientation information output from the orientation detection unit  442  to the image data. 
     As the orientation detection unit  442 , an acceleration sensor, a gyro sensor, or the like can be used. 
     In a case where the acceleration sensor and the gyro sensor are used as the orientation detection unit  442 , the orientation detection unit  442  can also detect movement of the digital camera  400  (pan, tilt, lift, whether it is stationary, and the like). 
     An eyepiece unit  443  is a portion where an eye (object)  700  of a photographer approaches (contacts) the digital camera  400 . 
     An eye contact detection unit  444  is an approach or eye contact detection sensor that detects approach (eye contact) and separation (eye separation) of the eye  700  to and from the eyepiece unit  443 . 
     The eye contact detection unit  444  detects the contact of the eye  700  with the eyepiece unit  443  depending on whether a light-receiving portion (not illustrated) of an infrared proximity sensor receives light. 
     After the eye contact is detected, the system control unit  420  determines that the eyepiece unit  443  is in an eye contact state until the eye separation is detected. 
     After the eye separation is detected, the system control unit  420  determines that the eyepiece unit  443  is in a non-eye contact state until the eye contact is detected. 
     The infrared proximity sensor is an example, and another sensor can be adopted to the eye contact detection unit  444  as long as the sensor can detect approach of an eye or an object that can be regarded as an eye contact. 
     The above-described memory  421  also serves as a memory (a video memory) for image display. 
     The digital signal and the image data written to the memory  421  are displayed by a rear surface display unit  450  and an electronic viewfinder (EVF)  451  via the memory control unit  422 . 
     The rear surface display unit  450  performs display corresponding to the signal from the memory control unit  422 . 
     In a case where the eye contact detection unit  444  detects the eye contact, the EVF  451  performs display corresponding to the signal from the memory control unit  422 . 
     The digital signal that is obtained by performing A/D conversion on the analog signal generated in the image capturing unit  411  by the A/D converter  412  and stored in the memory  421  is sequentially transmitted to the rear surface display unit  450  or the EVF  451  and displayed thereon. 
     Accordingly, live-view imaging display, which is real-time display, can be performed. 
     The system control unit  420  switches display (a display state)/non-display (a non-display state) of the rear surface display unit  450  and the EVF  451  in response to the state detected by the above-described eye contact detection unit  444 . 
     During the non-eye contact state, the rear surface display unit  450  performs display, and the EVF  451  is brought into the non-display state. 
     Further, during the eye contact state, the EVF  451  performs display, and the rear surface display unit  450  is brought into the non-display state. 
     An operation unit  460  includes various operation members as input units for receiving an operation from a user. 
     The operation unit  460  includes the various operation members (a mode changeover switch  461 , a shutter button  462 , a first shutter switch  463 , a second shutter switch  464 , a touch panel  465 , and a power supply switch  466 ), which are described below. 
     Further, the operation unit  460  is an operation unit for inputting various operation instructions to the system control unit  420 . 
     The mode changeover switch  461  switches an operation mode of the system control unit  420  to any of a still image capturing mode, a moving image capturing mode, and the like. 
     Image capturing modes included in the still image capturing mode are an auto image capturing mode, an auto scene determination mode, and a manual image capturing mode. 
     The still image capturing mode further includes an aperture priority (Av) mode (Av mode), a shutter speed priority mode (Time-value (Tv) mode or Tv mode), and a program automatic exposure (AE) mode (P mode) as the image capturing modes. 
     Similarly, the moving image capturing mode may include a plurality of image capturing modes. 
     The shutter button  462  is a button for a photographer to issue an image capturing preparation instruction and an image capturing instruction. 
     The first shutter switch  463  is turned ON in the middle of an operation, namely half-pressing (the image capturing preparation instruction) of the shutter button  462  provided to the digital camera  400  and generates a first shutter switch signal SW 1 . 
     An image capturing preparation operation such as autofocus (AF) processing, AE processing, and AWB processing is started by the first shutter switch signal SW 1 . 
     The second shutter switch  464  is turned ON by completion of the operation, namely full pressing (the image capturing instruction) of the shutter button  462  and generates a second shutter switch signal SW 2 . 
     The system control unit  420  executes reading of the analog signal from the image capturing unit  411  and signal conversion processing by the A/D converter  412  and the image processing unit  413  by the second shutter switch signal SW 2 . 
     Further, the system control unit  420  starts an image capturing processing operation up to writing the image data temporarily stored in the memory  421  to the storage medium  600  described below. 
     The touch panel  465  is a device for detecting a touch or drag operation by a photographer. 
     The touch panel  465  is integrated with the rear surface display unit  450 , and an operation can be performed by touching the display unit of the rear surface display unit  450  with a finger. 
     The power supply switch  466  is a switch for switching ON/OFF of the power supply. The power supply control unit  431  controls the power supply from the power supply unit  430  by a switching operation on the power supply switch  466 . 
     A heat dissipation fan  470  is controlled by the system control unit  420  and cools the heat generating source inside the digital camera  400 . 
     The lens unit  500  is an interchangeable lens that can be attached to and detached from the digital camera  400 . 
     The lens  501  is a lens group for generating an optical image (an object image) from object light reflected by an object and includes a plurality of lenses, but one lens is illustrated in  FIG.  10    for the sake of simplicity. 
     The lens communication terminal  506  is a communication terminal for the lens unit  500  to communicate with the digital camera  400 . 
     The lens communication terminal  506  is electrically connected to the communication terminal  440  as described above, and thus the lens unit  500  can communicate with the system control unit  420  that controls the entire digital camera  400 . 
     Accordingly, the system control unit  420  can communicate with a lens system control circuit  505  and a diaphragm drive circuit  504  and control a position of a diaphragm  503  and a focus state of a real image obtained by shifting the lens  501 . 
     The storage medium  600  is a storage medium such as a memory card that can be attached to and detached from the digital camera  400  and store a captured image. 
     The storage medium  600  includes, for example, a secure digital (SD) card, a memory that retains data in the absence of a power supply such as a FLASH® memory, and a hard disk. 
     INDUSTRIAL APPLICABILITY 
     The technique according to the present disclosure is applied to an electronic device and an image capturing system. 
     According to an aspect of the present invention, it is possible to prevent an airflow from an airflow generation unit from being hindered by a flexible board and heat dissipation performance of an image capturing element from being reduced. 
     While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2021-191535, filed Nov. 25, 2021, which is hereby incorporated by reference herein in its entirety.