Patent Publication Number: US-11647268-B2

Title: Image pickup apparatus equipped with heat dissipation mechanism

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image pickup apparatus equipped with a heat dissipation mechanism that radiates heat generated inside the apparatus to an outside. 
     Description of the Related Art 
     Substrates that implement heat generating elements, such as a main process substrate that implements a semiconductor device for an image process and a sensor substrate that implements an image sensor, are mounted inside an image pickup apparatus. Heat generated by a heat generating element may deteriorate performance of another electric elements on the substrate that implements the heat generating element. Moreover, the heat generated by the heat generating element raises temperature of an exterior of the image pickup apparatus, which may give displeasure to a user who holds the image pickup apparatus. Accordingly, it is necessary to discharge the heat generated by the heat generating element to the outside efficiently. 
     As a method of discharging heat generated inside an image pickup apparatus to the outside, there is a forced air cooling method that takes in air from the outside of the image pickup apparatus using a fan into the apparatus, cools the inside of the apparatus with the taken air, and discharges the warmed air to the outside of the apparatus (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 2014-45345 (JP 2014-45345A)). 
     In recent years, a size and pixel number of an image sensor increase accompanying to a demand of enhancement of image quality, and a video capturing function in a high frame rate is demanded. These situations tend to increase the heat generation amount of heat generating elements, such as an image sensor and a semiconductor device for an image process. Accordingly, a method of efficiently solving various problems like image abnormality caused by the heat generated inside the image pickup apparatus is required. 
     SUMMARY OF THE INVENTION 
     The present invention provides an image pickup apparatus that can efficiently solve problems caused by heat generated by a heat generating element. 
     Accordingly, a first aspect of the present invention provides an image pickup apparatus including a sensor substrate configured to implement an image sensor, and a main circuit board configured to implement a heat generating element. A length of the main circuit board is longer than a length of the sensor substrate in a width direction of the image pickup apparatus. The main circuit board is aslant arranged to an optical axis of the image pickup apparatus so that a first space part will be provided between the sensor substrate and the main circuit board. A cross section of the first space part in a plane that is parallel to both the optical axis and the width direction is approximately triangle. 
     According to the present invention, the image pickup apparatus can efficiently solve problems caused by heat generated by a heat generating element. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a first external perspective view showing an image pickup apparatus according to one embodiment. 
         FIG.  1 B  is a second external perspective view showing the image pickup apparatus. 
         FIG.  1 C  is a third external perspective view showing the image pickup apparatus. 
         FIG.  1 D  is an exploded perspective view showing the image pickup apparatus by dividing into rough units. 
         FIG.  2 A  is a first exploded perspective view showing a main unit of the image pickup apparatus. 
         FIG.  2 B  is a second exploded perspective view showing the main unit. 
         FIG.  3 A  and  FIG.  3 B  are perspective views showing the main unit viewed from different directions, respectively. 
         FIG.  4 A  is a back view showing the main unit. 
         FIG.  4 B  is a sectional view showing the main unit taken along the line A-A in  FIG.  4 A  and is a first view describing an airflow in a main duct in the image pickup apparatus. 
         FIG.  5    is a second view describing the airflow in the main duct. 
         FIG.  6 A  is a first exploded perspective view showing the main duct and a sensor duct in the image pickup apparatus. 
         FIG.  6 B  is a second exploded perspective view showing the main duct and the sensor duct. 
         FIG.  7 A  and  FIG.  7 B  are views respectively describing the airflow in the main duct and the airflow in the sensor duct. 
         FIG.  8 A  and  FIG.  8 B  are views describing a thermal connection between the main duct and a main circuit board. 
         FIG.  9 A  and  FIG.  9 B  are views describing a thermal connection between the sensor duct and a sensor unit. 
         FIG.  10 A  is a front view showing the image pickup apparatus. 
         FIG.  10 B  is a first sectional view showing the image pickup apparatus taken along the line D-D in  FIG.  10 A . 
         FIG.  10 C  is a second sectional view showing the image pickup apparatus taken along the line D-D in  FIG.  10 A . 
         FIG.  11 A  is a perspective view showing a positional relationship between a rear cover and the main circuit board in the image pickup apparatus. 
         FIG.  11 B  is a top view showing the positional relationship between the rear cover and the main circuit board in the image pickup apparatus. 
         FIG.  12 A  is a front view showing a positional relationship between a battery chamber provided in the rear cover and the main circuit board in the image pickup apparatus. 
         FIG.  12 B  is a view describing an effect obtained by arranging the main circuit board aslant to an optical axis. 
         FIG.  13 A  is a back view showing the image pickup apparatus. 
         FIG.  13 B  is a sectional view showing the image pickup apparatus taken along a line E-E in  FIG.  13 A . 
         FIG.  14 A  is an exploded perspective view describing an attachment of an L cover in the image pickup apparatus. 
         FIG.  14 B  is a left side view showing the image pickup apparatus. 
         FIG.  15 A ,  FIG.  15 B , and  FIG.  15 C  are sectional views showing the image pickup apparatus taken along a line F-F in  FIG.  14 B . 
         FIG.  16    is an exploded perspective view showing an ND unit in the image pickup apparatus. 
         FIG.  17 A ,  FIG.  17 B , and  FIG.  17 C  are the views describing an insertion state and a retraction state of an optical filter of the ND unit. 
         FIG.  18    is a front view showing a positional relationship between an engagement part of a filter holder in the ND unit, a drive train, and a detection switch. 
         FIG.  19 A  and  FIG.  19 B  are views showing a simplified configuration of a filter support unit in the ND unit. 
         FIG.  20 A  and  FIG.  20 B  are front views showing the configuration of the ND unit.  FIG.  20 C  is an enlarged view in an area S 30  in  FIG.  20 A . 
         FIG.  21    is a partial enlargement view showing a filter drive unit in the ND unit. 
         FIG.  22    is an external perspective view showing the image pickup apparatus in a state where a mount adapter is attached. 
         FIG.  23    is a perspective view showing a state where a lens and the mount adapter are detached from a camera body of the image pickup apparatus in  FIG.  22   . 
         FIG.  24    is a front view showing the camera body of the image pickup apparatus. 
         FIG.  25 A  and  FIG.  25 B  are sectional views showing the camera body taken along a line G-G in  FIG.  24   . 
         FIG.  26 A  and  FIG.  26 B  are perspective views showing the image pickup apparatus viewed from a grip unit side. 
         FIG.  27    is a top view showing the image pickup apparatus. 
         FIG.  28    is a side view showing a handle unit that constitutes the image pickup apparatus. 
         FIG.  29    is an exploded perspective view showing the handle unit. 
         FIG.  30    is a sectional view showing the handle unit taken along a line H-H in  FIG.  28   . 
         FIG.  31    is a perspective view showing one state of a display panel attached to the handle unit. 
         FIG.  32 A  and  FIG.  32 B  are side views showing examples of attachment states of the display panel to the handle unit. 
         FIG.  33 A  and  FIG.  33 B  are views describing an annular handle assembled by two handle parts. 
         FIG.  34 A  and  FIG.  34 B  are plan views showing the annular handle viewed in a direction of an arrow shown in  FIG.  33 A . 
         FIG.  35    is a view showing one state where the display panel is attached to the annular handle. 
         FIG.  36 A  and  FIG.  36 B  are sectional views showing the annular handle taken along a line K-K in  FIG.  35    and a line J-J in  FIG.  33 A , respectively. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereafter, embodiments according to the present invention will be described in detail by referring to the drawings. 
       FIG.  1 A ,  FIG.  1 B , and  FIG.  1 C  are external perspective views showing an image pickup apparatus  1  according to one embodiment of the present disclosure viewed from different directions, respectively. 
     An orthogonal coordinate system that consists of an X-axis, a Y-axis, and a Z-axis that mutually intersect at the right angle is defined in  FIG.  1 A ,  FIG.  1 B , and  FIG.  1 C  for convenience of description. The Z-axis is parallel to a photographing optical axis of the image pickup apparatus  1 . A direction directed from the image pickup apparatus  1  toward an object (not shown) is a forward direction (+Z). Moreover, the X-axis is parallel to a width direction of the image pickup apparatus  1  in a plane that intersects perpendicularly with the Z-axis. A direction directed from the left side toward the right side when the image pickup apparatus  1  is viewed from the object side is a forward direction (+X). The Y-axis that intersects perpendicularly with the X-axis and the Z-axis is parallel to a height direction. A direction directed from a bottom side toward an upper side is a forward direction (+Y). 
     The image pickup apparatus  1  has an image pickup apparatus body  2  (hereinafter referred to as a “camera body  2 ”), a lens  3 , a grip belt  4 , and a handle unit  4000 . The camera body  2  contains main functions of the image pickup apparatus  1 , such as a main control substrate that totally controls the image pickup apparatus  1 , an image sensor that converts incident light through the lens  3  into an electrical signal, a power source, and a recording unit that records image data. 
     Various kinds of operating members and terminals are arranged in predetermined positions of the external appearance of the camera body  2 . For example, the camera body  2  of the image pickup apparatus  1  is provided with operation members, such as a power switch  5  that switches ON/OFF of the power source of the image pickup apparatus  1 , a release button that instructs a photographing start, a menu button for various settings, a move button, and a selection button. Moreover, the camera body  2  is provided with a medium lid  6  that protects a contained recording medium, such as a card type recording medium, and a microphone unit  700  that records external voice. Furthermore, the camera body  2  is provided with an external terminal lid  7  that protects connection terminals, such as a USB terminal and a HDMI (registered trademark) terminal, that are used for connection with external devices. 
     A DC jack lid  8  that protects a DC jack terminal and a battery chamber  201   a  that stores a battery are provided in a back side (−Z side) of the camera body  2 . Internal tripod threads  11   a ,  11   b , and  11   c  for supporting the camera body  2  with a tripod or a rig are provided in a bottom cover  10  arranged at the bottom side (−Y side) of the camera body  2 . 
     The lens  3  is attached to the front side (+Z side) of the camera body  2 . Various lenses that are different in focal length, an open F value, and a zoom function, etc. are prepared. A user can exchange the lens  3  attached to the camera body  2  in accordance with a photographing condition. 
     The camera body  2  mounts a forced air cooling function using a fan as a cooling mechanism for cooling heat generating elements (various kinds of electronic parts that generate heat by operating) implemented on substrates contained. The camera body  2  has a main body inlet port  12  that opens toward the +X-direction of the camera body  2  as an inlet port ( FIG.  1 B ). Moreover, the camera body  2  has a first body exhaust port  13  that opens toward the −X-direction as an exhaust port ( FIG.  1 A ). Then, a second body exhaust port  14  that opens toward the −Y-direction is provided in the bottom cover  10  and a third body exhaust port  15  is provided in the battery chamber  201   a  ( FIG.  1 C ). 
     The image pickup apparatus  1  is configured so as to attach the grip belt  4 , which assists grip of the grip unit  300  by a user (photographing person), to the lower part of the first body exhaust port  13 . Accordingly, when the user holds the camera body  2  using the grip belt  4 , an exhaust wind does not hit a gripping hand. Moreover, the second body exhaust port  14  opens to the back side (−Z side) of the camera body  2  and does not open to the front side (+Z side). Accordingly, since the second body exhaust port  14  cannot be seen when the image pickup apparatus  1  is seen from the front side, a fine view is maintained. Moreover, since the second body exhaust port  14  is not closed by a floor when the camera body  2  is put on the floor, exhaust air can escape to the back side without being disturbed by the floor, which does not impair cooling performance of the camera body  2 . 
     When a battery is stored in the battery chamber  201   a , a certain distance is held between the third body exhaust port  15  and the battery, which secures an exhaust air flow passage. In the meantime, since the battery hides the third body exhaust port  15 , the third body exhaust port  15  cannot be seen by the user, which maintains the fine view. It should be noted that details of the forced air cooling, such as an arrangement of a cooling fan, will be mentioned later. 
       FIG.  1 D  is an exploded perspective view showing the image pickup apparatus  1  by dividing into rough units. The camera body  2  is provided with an F unit  2000 , an ND unit  1000 , a sensor unit  108 , a main unit  100 , and a rear unit  200  that are arranged toward the −Z side from the +Z side. moreover, the camera body  2  is provided with an R unit  400  in the +X side, a grip unit  300  at the −X side, a bottom unit  600  in the −Y side, and a top unit  3000  and handle unit  4000  at the +Y side. 
     The main unit  100  has forced cooling components, such as a duct and a cooling fan. The rear unit  200  has a liquid crystal panel and the battery chamber  201   a . The grip unit  300  contains recording media. The R unit  400  has an external connection terminal and the main body inlet port  12 . The sensor unit  108  has a sensor substrate in which an image sensor is implemented. The ND unit  1000  is provided with a plurality of optical filters that adjust a light amount entering into the image sensor. The F unit  2000  has a mount part for detaching and attaching the lens  3 . The bottom unit  600  has a tripod part. The top unit  3000  has the power switch  5 . The handle unit  4000  can be detachably attached to the top unit  3000 . It should be noted that the lens  3  is detachably attached to the mount part of the F unit  2000 . 
     Assembly procedures of the image pickup apparatus  1  are as follows. First, the main unit  100  is attached to the rear unit  200 , the grip unit  300  is attached to this, and then the R unit  400  is attached. The F unit  2000  to which the sensor unit  108  and ND unit  1000  are attached is attached to the units assembled so far. When the top unit  3000  and the bottom unit  600  are further attached, the camera body  2  is completed. When the desired lens  3  is attached to the F unit  2000  and the handle unit  4000  is attached to the top unit  3000 , the image pickup apparatus  1  is completed. It should be noted that details of the ND unit  1000 , F unit  2000 , top unit  3000 , and handle unit  4000  will be mentioned later. 
     Next, the heat dissipation system of the image pickup apparatus  1  will be described.  FIG.  2 A  and  FIG.  2 B  are the exploded perspective views showing the main unit  100  that has a heat dissipation mechanism viewed from different directions, respectively.  FIG.  3 A  and  FIG.  3 B  are perspective views showing the main unit  100  viewed from different directions, respectively. 
     As shown in  FIG.  2 A  and  FIG.  2 B , the heat dissipation system of the image pickup apparatus  1  is constituted by a main circuit board  101 , a cooling fan  102 , a cooling fan cushion  103 , a main duct  104 , a heat dissipation rubber  105 , a sensor duct  106 , a sensor heat dissipation member  107 , and the sensor unit  108 . The main circuit board  101  implements heat generating elements, such as an image processing semiconductor device, that generate heat during operations. Accordingly, the main circuit board  101  is one of heating components. Moreover, since the sensor unit  108  also includes the image sensor that generates heat during an operation, the sensor unit  108  is one of the heating components. 
     In the image pickup apparatus  1 , air taken in by the cooling fan  102  into the inside from the outside of the camera body  2  flows into the main duct  104  and sensor duct  106  that are made from metal material, such as aluminum, that has high thermal conductivity. Since the heat is exchanged between the air flowing into these ducts and the heat dissipation rubber  105  and sensor heat dissipation member  107  that have high thermal conductivity, the main circuit board  101  and sensor unit  108 , which are the heating components, are cooled, and the heated air is discharged to the outside. 
     It should be noted that an inlet port  104   a  of the main duct  104  shown in  FIG.  3 A  is connected to the main body inlet port  12  shown in  FIG.  1 B . A first exhaust port  104   b  shown in  FIG.  3 B  is connected to the first body exhaust port  13  shown in  FIG.  1 A . A second exhaust port  104   c  is connected to the second body exhaust port  14  shown in  FIG.  1 C . And a third exhaust port  104   d  is connected to the third body exhaust port  15  shown in  FIG.  1 C . Details of the heat dissipation system will be mentioned later. 
     Next, the airflow in the main duct  104  will be described.  FIG.  4 A  is a back view (viewed from the −Z side) of the main unit  100 .  FIG.  4 B  is a sectional view taken along a line A-A shown in  FIG.  4 A  and is a view describe an airflow in the main duct  104 . It should be noted that the sensor duct  106  and the sensor heat dissipation member  107  are not displayed in  FIG.  4 A  and  FIG.  4 B .  FIG.  5    is a view showing the airflow flowing through the main duct  104  in a state where the main unit  100  is partially omitted. It should be noted that  FIG.  5    shows the main duct  104  in a simplified form. As shown by arrows FL 1 , FL 2 , and FL 3 , the air inhaled from the inlet port  104   a  by the cooling fan  102  passes along the cooling fan  102  and is exhausted from three places, the first exhaust port  104   b , the second exhaust port  104   c , and the third exhaust port  104   d.    
     Next, the airflow in the sensor duct  106  will be described.  FIG.  6 A  and  FIG.  6 B  are exploded perspective views showing the main duct  104  and sensor duct  106  viewed from different directions, respectively. 
     In order to send the air flowing in the main duct  104  into the sensor duct  106 , a first sensor-duct opening  104   e  and second sensor-duct opening  104   f  are provided in the main duct  104 . Moreover, the sensor duct  106  is provided with a first main duct opening  106   a  and a second main duct opening  106   b  in positions that face these openings of the main duct  104  in the Z direction. The first sensor-duct opening  104   e  is connected to the first main duct opening  106   a , and the second sensor-duct opening  104   f  is connected to the second main duct opening  106   b.    
       FIG.  7 A  is a view describing the airflow toward the first sensor-duct opening  104   e  in the main duct  104 .  FIG.  7 B  is a view describing the airflow toward the second main duct opening  106   b  in the sensor duct  106 . It should be noted that  FIG.  7 A  and  FIG.  7 B  do no show a main duct cover  104   g , a sensor duct plate  106   c , and the cooling fan  102 . As shown by an arrow FL 4 , the air flowing through the main duct  104  is guided to the first sensor-duct opening  104   e . The air guided to the first sensor-duct opening  104   e  is introduced into the sensor duct  106  through the first main duct opening  106   a . As shown in an arrow FL 5  in  FIG.  7 B , the air introduced into the sensor duct  106  through the first main duct opening  106   a  passes through the inside of the sensor duct  106  and flows to the second main duct opening  106   b . The air that flows into the second main duct opening  106   b  returns to the main duct  104  through the second sensor-duct opening  104   f  connected to the second main duct opening  106   b , and then, the air is exhausted from the first exhaust port  104   b.    
     In this way, the air inhaled from the inlet port  104   a  passes through the main duct  104  and sensor duct  106 , and is exhausted from the first exhaust port  104   b , the second exhaust port  104   c , and the third exhaust port  104   d  in the image pickup apparatus  1 . Meanwhile, since the heat is exchanged with the air in the main duct  104  and sensor duct  10 , the heating components arranged inside the image pickup apparatus  1  are cooled. 
       FIG.  8 A  and  FIG.  8 B  are views describing a thermal connection between the main duct  104  and the main circuit board  101 . Specifically.  FIG.  8 A  is a back view showing the positional relationship between the main duct  104  and the main circuit board  101 .  FIG.  8 B  is a sectional view taken along a line B-B shown in  FIG.  8 A . 
     A first heat generating element  101   a , a second heat generating element  101   b , and a third heat generating element  101   c  are implemented in the main circuit board  101 . These heat generating elements are thermally connected to the main duct  104  through the heat dissipation rubber  105 . Thereby, since the heat is exchanged between the main duct  104  and the air, the first heat generating element  101   a , the second heat generating element  101   b , and the third heat generating element  101   c  can be cooled. It should be noted that the number of the heat generating elements implemented in the main circuit board  101  may not be restricted to three, may be less or more. 
       FIG.  9 A  and  FIG.  9 B  are views describing a thermal connection between the sensor duct  106  and the sensor unit  108 . Specifically,  FIG.  9 A  is a back view showing the positional relationship between the sensor duct  106  and the sensor unit  108 .  FIG.  9 B  is a sectional view taken along a line C-C shown in  FIG.  9 A . The heat generated in the sensor unit  108  is conducted to the sensor duct  106  through the sensor heat dissipation member  107  that has high thermal conductivity. Thereby, the sensor unit  108  can be cooled by exchanging the heat between the sensor duct  106  and the air. 
     As mentioned above, the main duct  104  and the sensor duct  106  perform the cooling function as heat sinks. When focusing on the positional relationship with the cooling fan  102 , the sensor duct  106  as an image sensor heat sink (first heat sink) that cools the sensor unit  108  is provided in the exhaust side of the cooling fan  102  as shown by the airflow shown in  FIG.  7 B  in this embodiment. Moreover, as shown in  FIG.  4 B , the main duct  104  as a main-circuit-board heat sink (second heat sink) that cools the main circuit board  101  is provided in the inlet side and exhaust side of the cooling fan  102 . 
     However, the embodiment is not limited to the structure where the image sensor heat sink is arranged at the exhaust side of the cooling fan  102  and the main-circuit-board heat sink is arranged in the inlet side and exhaust side. The main-circuit-board heat sink may be arranged in the inlet side only or the exhaust side only. Moreover, the image sensor heat sink and the main-circuit-board heat sink may be arranged in the inlet side of the cooling fan  102 . 
     Next, an inner layout of the image pickup apparatus  1  will be described.  FIG.  10 A  is a front view showing the image pickup apparatus  1 .  FIG.  10 B  and  FIG.  10 C  are sectional views taken along a line D-D shown in  FIG.  10 A .  FIG.  10 B  is a view describing a relation between the layout of the main circuit board  101  and sensor substrate  109  and the sensor duct  106 .  FIG.  10 C  is a view describing the influence of the heat that is generated by the main circuit board  101  on vicinities of the main circuit board  101 . 
     It is necessary to arrange the sensor substrate  109  so that the image pickup surface of the implemented image sensor  2006  will perpendicularly intersect with an optical axis Oa. There is no such restriction in the main circuit board  101 . The length of the main circuit board  101  is longer than the length of the sensor substrate  109  in the width direction of the image pickup apparatus  1 , Accordingly, in the camera body  2 , the main circuit board  101  is aslant arranged to the optical axis Oa (not to intersect perpendicularly) so that a first space part S 1  will be provided between the sensor substrate  109  and the main circuit board  101 . A cross section of the first space part S 1  in an XZ plane that is parallel to both the optical axis Oa and the width direction (X-direction) is approximately triangle. An efficient arrangement of the sensor duct  106  and efficient waste heat become available by arranging the sensor duct  106  to the first space part S 1  formed in this way. 
     Moreover, an operation substrate  310  that implements a grip operating member  301  is arranged inside the grip unit  300  so as to be approximately parallel to the sensor substrate  109  at the back side of the image pickup apparatus  1 . Accordingly, since the main circuit board  101  is aslant arranged to the optical axis Oa, a second space part S 2  is formed between the operation substrate  310  and the main circuit board  101 . A cross section of the second space part S 2  in the XZ plane is approximately triangle. A part of the main duct  104  that cools the main circuit board  101  is arranged in the second space part S 2 . Since the second space part S 2  reduces heat transmission from the main circuit board  101  to the operation substrate  310 , the temperature rise of the grip unit  300  whole including the grip operating member  301  can be reduced. 
     If the main circuit board  101  is provided in parallel to the sensor substrate  109 , the distance between both substrates is constant in the distance L 1  in  FIG.  10 C , for example. Against this, in the image pickup apparatus  1 , since the main circuit board  101  is aslant arranged, the distance L 11  becomes longer than the distance L 1  at a certain position, which reduces the heat conducted from the sensor substrate  109  from the main circuit board  101  as compared with the case where both the substrates are arranged in parallel. Accordingly, occurrence of an image abnormality due to the heat conducted from the main circuit board  101  to the sensor substrate  109  can be reduced, which addresses one of the thermal issues related to the specification of the image pickup apparatus  1 . 
     Moreover, the distance between the operation substrate  310  of the grip unit  300  and the main circuit board  101  is L 2  shown in  FIG.  10 C  in a case where the main circuit board  101  is arranged in approximately parallel to the sensor substrate  109 . Against this, in the image pickup apparatus  1 , since the main circuit board  101  is aslant arranged, the distance L 12  becomes longer than the distance L 2  at a certain position, which reduces the heat conducted to the grip operating member  301  from the main circuit board  101  because the both become distant. That is, since the temperature rise of the grip operating member  301  is reduced, unpleasant feeling of a user who operates the grip operating member  301  can be reduced or abolished. 
       FIG.  11 A  is a perspective view showing the positional relationship between the rear cover  201  and the main circuit board  101 .  FIG.  11 B  is a top plan (view seen from the +Y side) showing the positional relationship between the rear cover  201  and the main circuit board  101 .  FIG.  12 A  is a front view showing the positional relationship between the battery chamber  201   a  of the rear cover  201  and the main circuit board  101 .  FIG.  12 B  is a view describing an effect obtained by arranging the main circuit board  101  aslant to the optical axis Oa. 
     As shown in  FIG.  12 A , a part of the main circuit board  101  overlaps with the battery chamber  201   a  on a plane of projection in the optical axis direction. Accordingly, if the main circuit board  101  is not arranged aslant against the present embodiment, it becomes necessary to cut the main circuit board  101  in an interaction region S 10  shown in  FIG.  12 B  so that the main circuit board  101  may not interfere with the battery chamber  201   a.    
     Against this, in the image pickup apparatus  1 , the main circuit board  101  is aslant arranged to the optical axis Oa as shown in  FIG.  10 B  and  FIG.  10 C . Accordingly, since it is unnecessary to cut the main circuit board  101  in the interaction region S 10  that avoids the battery chamber  201   a  of the rear cover  201 , the substrate area can be increased, which enables expansion of the functions of the image pickup apparatus  1 . 
     As shown in  FIG.  10 B , in the image pickup apparatus  1 , the main duct  104  is aslant arranged to the optical axis Oa. Then, the cooling fan  102  is arranged in a space part of which the cross section is approximately triangle formed by the product contour and the main duct  104 . Since the cooling fan  102  is arranged in the space part of which the cross section is approximately triangle, the cooling fan  102  can be arranged without enlarging the product contour in the width direction. 
     Moreover, since the cooling fan  102  is arranged in that position, the distance from the sensor substrate  109  and microphone unit  700 , which is located in the front face of the camera body  2 , to the cooling fan  102  across the main duct  104  can be long. Since this reduces influence of noise of the cooling fan  102  on the sensor substrate  109  and the microphone unit  700 , high imaging quality and high voice quality can be obtained. 
     As shown in  FIG.  10 B  and  FIG.  10 C , the grip unit  300  provides recording medium slots  302  (media accommodation unit) that accommodate recording media that store photographed image data, captured video data, audio data, etc. in the image pickup apparatus  1 . The recording medium slots  302  are aslant arranged to the optical axis Oa. This enables to arrange the recording medium slots  302  into the grip unit  300  without enlarging the contour of the grip unit  300 . 
     Next, a heat insulation effect by the main duct  104  will be described.  FIG.  13 A  is a back view showing the image pickup apparatus  1 .  FIG.  13 B  is a sectional view taken along a line E-E in  FIG.  13 A .  FIG.  13 B  shows the positional relationship among the main circuit board  101 , the main duct  104 , the grip operating member  301  of the grip unit  300 , and a grip exterior member  303 . The heat generating element  110  is implemented in the main circuit board  101 . 
     If the heat generated by the heat generating element  110  implemented in the main circuit board  101  is conducted to the grip operating member  301  or the grip exterior member  303 , a user will feel uncomfortable when touching the grip operating member  301  or the grip exterior member  303 . In order to avoid this, in the image pickup apparatus  1 , the main duct  104  is arranged between the heat generating element  110  and the grip operating member  301  and grip exterior member  303 . That is, the conduction of the heat generated by the heat generating element  110  to the grip operating member  301  and the grip exterior member  303  is interrupted by the main duct  104 . In this way, since the temperature rise of the grip operating member  301  and the grip exterior member  303  can be reduced, a user does not feel uncomfortable. 
       FIG.  14 A  is an exploded perspective view describing attachment of an L cover  304  in the image pickup apparatus  1 .  FIG.  14 B  is a left side view of the image pickup apparatus  1 .  FIG.  15 A .  FIG.  15 B , and  FIG.  15 C  are sectional views showing the image pickup apparatus  1  taken along a line F-F in  FIG.  14 B .  FIG.  15 A  is an entire sectional view,  FIG.  15 B  is an enlarged view of an area S 20  in  FIG.  15 A , and  FIG.  15 C  is an enlarged view of an area S 21  in  FIG.  15 A . 
     The grip unit  300  is provided with the L cover  304 . As shown in  FIG.  14 B ,  FIG.  15 B , and  FIG.  15 C , a first grip-belt through hole (belt fixing part)  305  and a second grip-belt through hole (belt fixing part)  306  are provided in the grip unit  300 . 
     These grip-belt through holes are formed by not only the L cover  304  but also a first main duct grip ring  104   h  and a second main duct grip ring  104   i  that are formed as parts of the main duct  104 . 
     Since the main duct  104  is made from metal in consideration of thermal conductivity as mentioned above, its mechanical strength is large. Accordingly, since the strength of the first main duct grip ring  104   h  and second main duct grip ring  104   i  is also large, it is unnecessary to form the grip rings using other high-strength components. Accordingly, the number of components can be reduced, and the configuration equipped with the high-strength grip rings can be achieved without enlarging the image pickup apparatus  1 . 
     Next, the configuration of the ND unit  1000  will be described. The ND unit  1000  contains four optical filters (optical components)  1001   a ,  1001   b ,  1001   c , and  1001   d  of which optical densities differ in this embodiment. Each of the optical filters  1001   a  through  1001   d  is movable between an insertion position where a filter is inserted into a beam passing area  1002  and a retraction position where a filter is retracted from the beam passing area  1002  according to a user&#39;s operation. The user can adjust an amount of light entering into the image sensor  2006  by moving the desired optical filter(s) to the insertion position. 
       FIG.  16    is an exploded perspective view showing the ND unit  1000 . The ND unit  1000  is provided with a filter support unit  1003  that supports the optical filters  1001   a  through  1001   d , two filter drive units  1004   a  and  1004   c  having drive mechanisms that move the optical filters  1001   a  through  1001   d . In order to slim down the ND unit  1000 , the four optical filters are divided into two sets each of which has two optical filters. The two sets are arranged at positions shifted in the Z direction. Two optical filters of each set are arranged in the same plane parallel to the XY plane. When one of the optical filters  1001   c  and  1001   d  is inserted into the beam passing area  1002 , the other optical filter is retracted from the beam passing area  1002 . Similarly, when one of the optical filters  1001   a  and  1001   b  is inserted into the beam passing area  1002 , the other optical filter is retracted from the beam passing area  1002 . As mentioned below, all the optical filters  1001   a  through  1001   d  can be held in the state where they are retracted from the beam passing area  1002 . 
     The filter drive units  1004   a  and  1004   c  are arranged so as to face each other in the Z direction across the filter support unit  1003 . The filter drive unit  1004   a  drives the optical filters  1001   a  and  1001   b . The filter drive unit  1004   c  drives the optical filters  1001   c  and  1001   d.    
       FIG.  17 A ,  FIG.  17 B , and  FIG.  17 C  are the views describing the insertion states and the retraction states of the optical filters  1001   a  and  1001   b . The optical filters  1001   a  and  1001   b  are respectively held by filter holders  1005   a  and  1005   b  as holding members. The filter holder  1005   a  engages with metal-made guide shafts (guide members)  1001   a  and  1006   b  extended in the Y direction. The filter holder  1005   b  engages with guide shafts (guide members)  006   a  and  1006   b.    
     The filter holder  1005   a  provides a rack meshed with a drive train  1007   a , which is constituted by a plurality of gears, in an engagement part to the guide shaft  1006   a . When a motor  1008   a  is driven, driving force is transmitted to the filter holder  1005   a  through the drive train  1007   a , and the filter holder  1005   a  moves in the Y direction while being guided by the guide shafts  1006   a  and  1006   b . In this way, the insertion state (insertion position) and the retraction state (retraction position) of the optical filter  1001   a  with respect to the beam passing area  1002  can be switched. 
     Similarly, the filter holder  1005   b  provides a rack meshed with a drive train  1007   b , which is constituted by a plurality of gears, in an engagement part to the guide shaft  1006   b . When a motor  1008   b  is driven, driving force is transmitted to the filter holder  1005   b  through the drive train  1007   b , and the filter holder  1005   b  moves in the Y direction while being guided by the guide shafts  1006   a  and  1006   b . In this way, the insertion state and the retraction state of the optical filter  1001   b  with respect to the beam passing area  1002  can be switched. 
     In the state in  FIG.  17 A , the optical filter  1001   a  is in the insertion state and the optical filter  1001   b  is in the retraction state. In the state in  FIG.  17 B , both the optical filters  1001   a  and  1001   b  are in the retraction state. In the state in  FIG.  17 C , the optical filter  1001   b  is in the insertion state and the optical filter  1001   a  is in the retraction state. 
     The ND unit  1000  is provided with a detector that detects whether each of the optical filters  1001   a  through  1001   d  is in the insertion state or the retraction state with respect to the beam passing area  1002 . The detector employs a mechanical detector that detects movement of a detection lever rather than an optical detector like a photo coupler in consideration of optical influence on the incident beam through the lens  3 . 
     For example, as shown in  FIG.  17 A , an insertion detection switch  1009   a  that detects the insertion state of the optical filter  1001   a  into the beam passing area  1002  and a retraction detection switch  10111   a  that detects the retraction state are arranged in the filter drive unit  1004   a . These switches are the mechanical detectors. The insertion detection switch  1009   a  and the retraction detection switch  1011   a  are arranged in the positions that face each other in the moving direction of the optical filter  1001   a  across the beam passing area  1002 . When the optical filter  1001   a  is in the insertion state, the filter holder  1005   a  presses an insertion detection lever  1010   a  ( FIG.  17 C ) of the insertion detection switch  1009   a . When the optical filter  1001   a  is in the retraction state, the filter holder  1005   a  presses a retraction detection lever  1012   a  of the retraction detection switch  1011   a.    
     Similarly, an insertion detection switch  1009   b  that detects the insertion state of the optical filter  1001   b  into the beam passing area  1002  and a retraction detection switch  1011   b  that detects the retraction state are arranged in the filter drive unit  1004   a . The insertion detection switch  1009   b  and the retraction detection switch  1011   b  are arranged in the positions that face each other in the moving direction of the optical filter  1001   b  across the beam passing area  1002 . When the optical filter  1001   b  is in the insertion state, the filter holder  1005   b  presses an insertion detection lever  1010   b  ( FIG.  17 A ) of the insertion detection switch  1009   b . When the optical filter  1001   b  is in the retraction state, the filter holder  1005   b  presses a retraction detection lever  1012   b  ( FIG.  17 C ) of the retraction detection switch  1011   b.    
       FIG.  18    is a front view describing arrangements of an engagement part  1013   b  of the filter holder  1005   b , the drive train  1007   b , the insertion detection switch  1009   b , and the retraction detection switch  1011   b . The insertion detection lever  1010   b  and the retraction detection lever  1012   b  are arranged so as to align on a straight line parallel to the moving direction of the optical filter  1001   b . Moreover, the engagement part  1013   b  where the filter holder  1005   b  receives the driving force from the drive train  1007   b  and the position where the filter holder  1005   b  receives reaction force from the insertion detection lever  1010   b  when the filter holder  1005   b  presses the insertion detection lever  1010   b  are almost aligned on a straight line. That is, the engagement part  1013   b , and the insertion detection switch  1009   b  and the retraction detection switch  1011   b  as the detectors that detect the position of the filter holder  1005   b  are arranged in the positions that overlap when viewed in the moving direction of the optical filter  1001   b . This prevents inclination of the filter holder  1005   b  even when the filter holder  1005   b  presses the insertion detection lever  1010   b  or the retraction detection lever  1012   b . As a result, increase in dynamic resistance and occurrence of operation failure due to a wrench of the filter holder  1005   b  to the guide shafts  1006   a  and  1006   b  that may occur because the filter holder  1005   b  inclines can be reduced. 
     Since the drive mechanisms of the filter holders  1005   a ,  1005   c , and  1005   d  other than the filter holder  1005   b  conform to the drive mechanism of the filter holder  1005   b , their descriptions are omitted. Moreover, the optical filters  1001   c  and  1001   d  can be switched between the insertion state and the retraction state as with the optical filters  1001   a  and  1001   b . Moreover, the detection method of the insertion state and retraction state of the optical filters  1001   c  and  1001   d  is the same as the detection method of the insertion state and the retraction state of the optical filters  1001   a  and  1001   b . Accordingly, descriptions about operations and state detections of the optical filters  1001   c  and  1001   d  are omitted. 
     When the insertion states and retraction states with respect to the beam passing area  1002  are switched by moving the filter holders  1005   a ,  1005   b ,  1005   c , and  1005   d  respectively holding the optical filters  1001   a ,  1001   b ,  1001   c , and  1001   d , there is a fear that static electricity occurred during the moving operations charges the optical filters  1001   a  through  1001   d  and dust in air easily adheres. Here, the ND unit  1000  is provided with an electrically discharging structure for preventing electrification of the optical filters  1001   a  through  1001   d . The electrically discharging structure will be described as follows. 
       FIG.  19 A  and  FIG.  19 B  are exploded perspective views simplifying and showing the configuration of the ND unit  1000 . For example, the optical filter  1001   a  is put and held between a metal filter cover (conductive member)  1014   a  and the filter holder  1005   a  that is made from conductive resin. The optical filters  1001   b ,  1001   c , and  1001   d  are also held between the metal filter covers  1014   b .  1014   c , and  1014   d  and the filter holders  1005   b ,  1005   c , and  1005   d.    
       FIG.  20 A  and  FIG.  20 B  are front views showing the ND unit  1000 .  FIG.  20 A  shows the retraction state of the optical filters  1001   a  and  1001   b .  FIG.  20 B  shows the insertion state of the optical filter  1001   a .  FIG.  20 C  is an enlarged view of the area S 30  in  FIG.  20 A . 
     The filter cover  1014   a  has elastic parts  1015   a  and  1016   a , and the filter cover  1014   b  has elastic parts  1015   b  and  1016   b . For example, when the optical filters  1001   a  and  1001   b  are in the retraction state as shown in  FIG.  20 A , the elastic parts  1016   a  and  1016   b  abut to an ND frame (frame body)  1017  that is made from conductive resin. The ND frame  1017  is a frame body of the filter support unit  1003  and is connected (grounded) to the camera body  2 . Moreover, when the optical filter  1001   a  is in the insertion state as shown in  FIG.  20 B , the elastic part  1016   b  of the filter cover  1014   b  abuts to the ND frame  1017 , and the filter cover  1014   a  abuts to the filter cover  1014   b . That is, even when the optical filter  1001   a  is in the insertion state, the filter cover  1014   a  is grounded to the ND frame  1017  through the filter cover  1014   b.    
     In this way, the filter holder  1005   a  is electrically connected to the ND frame  1017  in both the insertion state and retraction state with respect to the beam passing area  1002  and is grounded to the camera body  2  so that the electricity will be removed. Accordingly, electrification of the optical filter  1001   a  held by the filter holder  1005   a  can be prevented, and adhesion of dust to the optical filter  1001   a  can be reduced. Since such a configuration is common to the optical filters  1001   b  through  1001   d , their descriptions are omitted. 
     If the guide shafts  1006   a  and  1006   b  have shakiness in an axial direction, the guide shafts  1006   a  and  1006   b  may move with movements of the filter holders  1005   a  and  1005   b  in the axial direction. If the guide shafts  1006   a  and  1006   b  moves in the axial direction, those shaft ends will collide with the ND frame  1017  that supports the guide shafts  1006   a  and  1006   b , and collision sound (ambient noise) will occur. 
     In order to avoid occurrence of this, the filter support unit  1003  is configured to provide an elastic part  1018  in a part that supports the shaft ends of the guide shafts  1006   a  through  1006   d  in the ND frame  1017  as shown in  FIG.  20 C . It should be noted that  FIG.  20 C  shows the guide shafts  1006   a  and  1006   b  but omits showing the guide shafts  1006   c  and  1006   d . When the guide shafts  1006   a  through  1006   d  are attached to the ND frame  1017 , the elastic part  1018  deforms elastically and gives the guide shafts  1006   a  through  1006   d  the elastic force (energization force) in the axial direction, which can prevent the shakiness and can reduce occurrence of the ambient noise. 
     In the ND unit  1000 , the filter support unit  1003  and the filter drive unit  1004   a  and  1004   c  are assembled so that the filter holders  1005   a  through  1005   d  will be respectively engaged with the drive trains  1007   a ,  1007   b ,  1007   c , and  1007   d . In that time, respective engagement points ( 1013   a  in  FIGS.  21  and  1013     b  in  FIG.  18   , for example) of the filter holders  1005   a  through  1005   d  come inside drive-train supporting plates  1019   a  and  1019   c  ( FIG.  16   ) that support the drive trains  1007   a  through  1007   d.    
     Accordingly, since the engagement points of the filter holders  1005   a  through  1005   d  with the drive trains  1007   a  through  1007   d  are covered with the drive-train supporting plates  1019   a  and  1019   c , the engagement points cannot be seen when no countermeasure is taken. Accordingly, in the filter drive unit  1004   a , for example, a check hole  1020   a  is provided in the drive-train supporting plate  1019   a  at a position that overlaps with the engagement part  1013   a  when viewed in the optical axis direction as enlarged and shown in  FIG.  21    in this embodiment. As a result of this, a worker can visually check whether the drive engagement at the engagement point  1013   a  is normal through the check hole  1020   a , an action defect due to the engagement defect at the engagement point  1013   a , and deformation or breakage of components due to improper assembly are prevented. Check holes corresponding to the drive trains  1007   b  through  1007   d  are provided in the drive-train supporting plates  1019   a  and  1019   c  similarly. 
     Next, the configuration of the mount adapter  2001  will be described.  FIG.  22    is an external perspective view showing the image pickup apparatus  1  in a state where a lens  2003  is attached through the mount adapter  2001 . A camera mount of the lens  2003  is not directly connectable with a lens interchangeable mount  2002  (hereinafter referred to as a “mount  2002 ”) provided in the F unit  2000 . In this case, the mount adapter  2001   l  equipped with a lens interchangeable mount that suits the camera mount of the lens  2003  is attached to the mount  2002  of the camera body  2 , and the lens  2003  is attached to the mount adapter  2001 . Thereby, the user of the camera body  2  can use the lens  2003 . 
       FIG.  23    is a perspective view showing a state where the mount adapter  2001  and the lens  2003  are detached from the camera body  2 . Fixing flanges  2005  are provided in the mount adapter  2001 , and screw stop parts (adapter fixing parts), which correspond to the fixing flanges  2005 , are provided around the mount  2002  of the camera body  2  at four places that are symmetrical in vertical and horizontal directions to the optical axis of the camera body  2 . The mount adapter  2001  is fixed to the mount  2002  by screwing fixing screws  2004  to the mount fixing parts through the fixing flanges  2005 . For example, the mount  2002  of the camera body  2  is configured to fix a lens with a bayonet system. In this case, since the mount adapter  2001  is configured to fix to the mount  2002  with the fixing screws  2004  but is not configured to be detachably attached with the bayonet system, the mount adapter  2001  is firmly fixed to the mount  2002  without causing shakiness. 
       FIG.  24    is a front view showing the camera body  2 . Also when the mount adapter  2001  is not attached, as shown in  FIG.  24   , the fixing screws  2004  are screwed to the screw stop parts. Thereby, loss of the fixing screws  2004  can be prevented. 
     The image sensor  2006  is arranged nearly at the center of the mount  2002  when viewed from the front of the camera body  2 . A lens release button  2007  for detaching the lens  2003  from the camera body  2  is provided around the mount  2002  at a position that does not interfere with the screw stop parts to which the fixing screws  2004  are screwed and is opposite to the grip unit  300  across the mount  2002 . 
       FIG.  25 A  and  FIG.  25 B  are sectional views taken along a line G-G shown in  FIG.  24   .  FIG.  25 A  shows a state where neither the mount adapter  2001  nor the lens  2003  is attached to the mount  2002 .  FIG.  25 B  shows a state where the mount adapter  2001  is attached. A line  2043  shown in  FIG.  25 A  and  FIG.  25 B  shows a position of a mount assembly surface  2041 . The image sensor  2006  is arranged inside the camera body  2 , and the image sensor  2006  is implemented in the sensor substrate  109 . The sensor substrate  109  is fixed to a front base (holding base)  2045 . The mount  2002  is fixed to the front base  2045 . Moreover, the screw stop parts are provided in the front base  2045  and the fixing screws  2004  are screwed to the screw stop parts and are held. 
     In the state of  FIG.  25 A  where the mount adapter  2001  is not attached to the mount  2002 , a head  2042  of a fixing screw  2004  is located at the side (−Z side) of the image sensor  2006  than the mount assembly surface  2041 . That is, the fixing screw  2004  is not projected from the mount assembly surface  2041  to the +Z side. In the meantime, in the state of  FIG.  25 B  where the mount adapter  2001  is attached to the mount  2002 , the head  2042  of the fixing screw  2004  is located at the side (+Z side) of the mount adapter  2001  than the mount assembly surface  2041 . 
     Thereby, when the mount adapter  2001  is not attached to the mount  2002 , the fixing screw  2004  can be stored in the position that does not disturb attachment and detachment of the lens  2003 . 
     Next, the recording medium will be described.  FIG.  26 A  and  FIG.  26 B  are perspective views showing the image pickup apparatus  1  when viewed from the side of the grip unit  300 .  FIG.  26 A  shows a state where the medium lid  6  closed.  FIG.  26 B  shows a state where the medium lid  6  opened. The media lid  6  is provided in the object side (+Z side) of the grip unit  300 . When the medium lid  6  is opened, the two recording medium slots  302  (see  FIG.  10 B ) provided inside appear. In a state where the media lid  6  is opened, the user can insert or extract a first recording medium  3110   a  and second recording medium  3110   b , which store data captured by the image pickup apparatus  1 , with respect to the recording medium slots  302 .  FIG.  26 B  shows a state where the first recording medium  3110   a  and the second recording medium  3110   b  are accommodated in the recording medium slots  302 . 
     Although the image pickup apparatus  1  can accommodate two recording media including the first recording medium  3110   a  and the second recording medium  3110   b , it is enough to accommodate one or more recording media. 
     Since the two recording media  3110   a  and  3110   b  are attachable, data can be simultaneously recorded to both the recording media so as to use one recording medium as backup in a case where data in the other recording medium is damaged. In addition, this makes relay recording available for enabling long-time photographing. A translucent or transparent media window  3120  is provided in the medium lid  6 . Even when the medium lid  6  is closed, a user can check visually whether the recording media  3110   a  and  3110   b  are accommodated in the camera body  2  by viewing through the medium window  3120 . 
     Next, keys in the top unit  3000  will be described.  FIG.  27    is a top view showing the image pickup apparatus  1 . Various operating members are arranged in the side of the grip unit  300  of the top unit  3000 , i.e., the upper surface (top surface) of the camera body  2  so that a user can operate them in a state holding the grip unit  300 . A REC button  3210  for instructing to start and stop recording captured image data, an iris dial  3220  for changing an aperture value of the lens  3 , etc. are arranged in the front area (+Z side) at the side of the grip unit  300  of the top unit  3000 . The power switch  5 , a media button  3230 , a slot selection button  3240  (selection unit), and access LEDs (medium display unit)  3250   a  and  3250   b  are arranged in the rear area (−Z side) at the side of the grip unit  300  of the top unit  3000 . 
     By operating the media button  3230 , the user achieves transition to the state of checking the picked-up image data. By operating the slot selection button  3240 , the user can select one of the first recording medium  3110   a  and second recording medium  3110   b  to which the picked-up image is recorded. In that time, the user can confirm which of the two recording media  3110   a  and  3110   b  is used to record the image data by checking the access LEDs  3250   a  and  3250   b.    
     Since the image pickup apparatus  1  can accommodate the two recording media  3110   a  and  3110   b , the two access LEDs  3250   a  and  3250   b  are arranged side by side from the optical axis side. The first access LED  3250   a  near to the optical axis indicates the state of the first recording medium  3110   a  accommodated near the optical axis. The second access LED  3250   b  far from the optical axis indicates the state of the second recording medium  3110   b  far from the optical axis. That is, the arrangement relation of the recording media  3110   a  and  3110   b  matches that of the access LEDs  3250   a  and  3250   b . Thereby, even when the recording media and access LEDs are separately arranged, the user can distinguish intuitively which recording medium is indicated by an access LED. 
     It can be considered that the first recording medium  3110   a  and the second recording medium  3110   b  are arranged in this order from the front side of the camera body  2  (from the object side). Accordingly, although illustration is omitted, the first access LED  3250   a  may be arranged in the front side of the camera body  2  and the second access LED  3250   b  may be arranged in the rear side of the camera body  2 . Also, in this case, the user can distinguish intuitively which recording medium is indicated by an access LED. Also, in this case, the user can distinguish intuitively which recording medium is indicated by an access LED. 
     For example, the following state confirmation method of a recording medium using an access LED can be considered. Lighting in red of an access LED indicates that the corresponding recording medium is under recording, and lighting in green of the access LED indicates that the corresponding recording medium is in a recordable state (standby state). Thereby, the user can immediately check which recording medium is recording by seeing the color of the access LED. It should be noted that the access LED may distinguish a state by lighting and blinking instead of a lighting color. 
     Generally, since the slot selection button and access LED are related to the recording media, they are arranged near the medium lid in many cases. Against this, since the medium lid  6  of the image pickup apparatus  1  is arranged at the object side of the grip unit  300  as a grip part for holding the image pickup apparatus  1 , the medium lid  6  is covered by a user&#39;s hand when the user holds the camera body  2 . Accordingly, the slot selection button  3240  and access LEDs  3250   a  and  3250   b  are arranged on the top unit  3000  at the side of the grip unit  300  and at the −Z side. Thereby, the user can check the states of the recording media  3110   a  and  3110   b  and can select a slot in the state where the user holds the camera body  2 . 
     The media button  3230  and the slot selection button  3240  are arranged at the +X side of the first body exhaust port  13 . If the user tries to operate the media button  3230  or the slot selection button  3240  by an index finger while holding the camera body  2 , the index finger will cover the first body exhaust port  13 . Then, the exhaust wind warmed within the camera body  2  hits the user&#39;s index finger, which may give the user displeasure. 
     In order to avoid this, the image pickup apparatus  1  provides the first grip-belt through hole  305  just under the first body exhaust port  13  (the bottom side of the camera body  2  (−Y side)). Thereby, the movable range of the index finger is regulated with the grip belt  4  so that the media button  3230  and the slot selection button  3240  at the +X side of the first body exhaust port  13  cannot be operated by the index finger. Accordingly, since the user is naturally urged to use the thumb for operating the media button  3230  and the slot selection button  3240 , the user can operate them comfortably without exposing a finger to the exhaust wind. 
     The REC button  3210  and the iris dial  3220  are also arranged in the top unit  3000  as mentioned above. Since these operating members are used frequently at photographing, they are arranged at the front side (+Z side) than the first body exhaust port  13  and the first grip-belt through hole  305  in the image pickup apparatus  1  so that they can be operated by the index finger of the hand that holds the camera body  2 . Accordingly, when the user operates the REC button  3210  or the iris dial  3220  by the index finger of the hand that holds the camera body  2 , the motion of the index finger is not regulated by the grip belt  4  and the exhaust wind does not hit the index finger. 
       FIG.  28    is a side view showing the handle unit  4000 .  FIG.  29    is an exploded perspective view showing the handle unit  4000 . The handle unit  4000  is one of accessories that can be detachably attached to the camera body  2  and is fixed to the camera body  2  so that a long side will be parallel to the Z direction and will be extended to the +Z side as a basic configuration. The handle unit  4000  roughly consists of a handle part  4001  and a holder component  4002 . The handle part  4001  is approximately formed in an L-shape that includes a short side part and long side part extended in two directions. When the handle unit  4000  is attached to the image pickup apparatus  1 , a user grips a grip part  4001   a  of the long side part (part being approximately parallel to the Z-axis) of the handle part  4001 . 
     A long-side fastening part  4010  is formed at one end (tip end) of the handle part  4001  and a short-side fastening part  4020  is formed in the other end (base end). A through hole  4001   b  is provided in the long-side fastening part  4010 , and a through hole  4001   c  is provided in the short-side fastening part  4020 . Around the through holes  4001   b  and  4001   c , rosettes (chrysanthemum-shaped fixtures) are provided in both sides (±X sides) in the X-direction that is a fastening direction. Specifically, the rosette  4001   b - l  is provided around the through hole  4001   b  at the +X side, and the rosette  4001   b - 2  is provided around the through hole  4001   b  at the −X side. Similarly, the rosette  4001   c - 1  is provided around the through hole  4001   c  at the +X side, and the rosette  4001   c - 2  is provided around the through hole  4001   c  at the −X side. It should be noted that a rosette is provided with depressions and projections (hereinafter referred to as a “radial gear”) formed in uniform phase in normal line directions of the center axis of the through hole. When a pair of rosettes are faced and their radial gears are abutted and engaged, the phases and centers of the rosettes are matched. The rosettes can be combined by changing the interphase for every gear phase pitch. 
     The holder component  4002  is fixed to the camera body  2  by abutting an attachment surface  4002   a  to the camera body  2  and by screwing a handle bolt  4003  to a thread part (first fixing part) provided in the camera body  2  through a fixing hole (second fixing part)  4002   b  provided at the +Z side of the holder component  4002 . In the holder component  4002 , a through hole  4002   c  is provided in the end (−Z side) other than the fixing hole  4002   b  to the camera body  2 . Moreover, the fastening part (second fastening part) of the holder component  4002  is formed by providing a rosette  4002   c - 1  at the +X side around the through hole  4002   c  and by providing a rosette  4002   c - 2  at the −X side around the through hole  4002   c.    
     The rosette  4001   c - 1  that is provided in the short-side fastening part  4020  of the handle part  4001  is abutted to the rosette  4002   c - 2  that is provided in the holder component  4002  so that the through hole  4001   c  of the short-side fastening part  4020  will communicate with the through hole  4002   c  of the holder component  4002 . Furthermore, a fastening bolt  4004  is inserted through both the through hole  4001   c  of the short-side fastening part  4020  and the through hole  4002   c  of the holder component  4002  and is engaged to a fastening nut  4005 . Thereby, the handle part  4001  is firmly fixed to the holder component  4002  without rotating easily because the rosettes are engaged. 
       FIG.  30    is a sectional view showing the handle part  4001  taken along a line H-H in  FIG.  28   . The whole surface of the handle part  4001  becomes an appearance member in a product, and a fine view is required. In this embodiment, the handle part  4001  is manufactured by injection molding of resin material as one component. Accordingly, the thickness of the handle part  4001  should be uniform as possible in order to form the outside surface of the handle part  4001  smoothly. Accordingly, the handle part  4001  is configured to have an S-shaped section having depressions  4001   d  in both sides (+X side and −X side) in the X-direction. Thereby, the handle part  4001  secures high strength enough not to be broken when gripping the grip part  4001   a  while maintaining a fine view with uniform wall thickness. Moreover, since the depressions  4001   d  are formed alternately from the both sides in the X-direction, each the depressions becomes small (narrow), which prevents insertion of a finger into the depressions  4001   d  and improves the grip. It should be noted that such a cross section configuration of the handle part  4001  can be used for not only the L-shaped handle but also a handle of another shape made from resin material. 
       FIG.  31    is a perspective view showing one state where an accessory is attached to the handle unit  4000 . As mentioned above, the handle unit  4000  is basically attached to the camera body  2  at one position so that the long side part (the extended part of the grip part  4001   a ) will be parallel to the Z-direction (optical axis direction) and the tip end will be directed to the +Z side. In this case, an accessory can be attached to the tip of the gripping member  4001   a . In this example, a display panel  4006  for checking a photographed image and inputting an operation is attached as an accessory. 
     A holder component  4002 A that holds the display panel  4006  has the same configuration as the holder component  4002  and is giving versatility to the holder component  4002  as components in this way. The display panel  4006  is fixed by screwing to a fixing hole of the holder component  4002 A (equivalent to the fixing hole  4002   b  of the holder component  4002 , see  FIG.  29   ). Then, the display panel  4006  is fixed to the handle part  4001  by abutting a rosette of the holder component  4002 A (equivalent to the rosette  4001   c - 1  of the holder component  4002 ) to the rosette  4002   b - 1  of the long-side fastening part  4010  of the handle part  4001 , and by fastening with a bolt. In this state, since the display panel  4006  is in front of the camera body  2 , a user can easily photograph while watching the display panel  4006  when carrying the image pickup apparatus  1  on the shoulder. 
       FIG.  32 A  and  FIG.  32 B  are side views showing examples of attachment states of the display panel  4006  to the handle unit  4000 .  FIG.  32 A  shows the attachment state that is changed from the state of  FIG.  31    only in an attachment angle of the display panel  4006  to the holder component  4002 A. In the attachment state of  FIG.  32 A , since a screen of the display panel  4006  is directed in a slant upper direction, the user can easily check the display when photographing in low angle. 
       FIG.  32 B  shows the attachment state that is changed from the state of  FIG.  31    in the attachment angle of the handle unit  4000  to the camera body  2  and the attachment angle of the display panel  4006  to the handle unit  4000 . In the attachment state of  FIG.  32 B , since the display panel  4006  is arranged in a position projected to the back side (−Z side), the screen of the display panel  4006  can be seen from the back of the image pickup apparatus  1 , and accordingly persons other than the user can easily check an image. Moreover, this attachment state is useful when the image pickup apparatus  1  is attached to a tripod and the user checks the display from a back side that is distant from the image pickup apparatus  1 . 
       FIG.  33 A  is a side view showing an annular handle  4100  assembled using two handle parts  4001 E and  4001 F.  FIG.  33 B  is an exploded perspective view of the annular handle  4100 . The annular handle  4100  is constituted by rotating one of the handle parts  4001 E and  4001 F around the X-axis by 180 degrees and by combining and fastening to each other. It should be noted that the handle part  4001 E and  4001 F are identical to the handle part  4001  shown in  FIG.  28   . 
     A rosette  4001   c - 1  of the handle part  4001 E is engaged to a rosette  4001   b - 2  of the handle part  4001 F, and a rosette  4001   b - 2  of the handle part  4001 E is engaged to a rosette  4001   c - 1  of the handle part  4001 F. Then, the fastening bolts  4004  inserted into the through holes of the respective engagement parts are screwed to the fastening nuts  4005  in the X-direction. Thereby, the annular handle  4100  is obtained. A fixing hole  4001   g  that is a fixing part to the camera body  2  is provided in the center position of the long side part of each of the handle parts  4001 E and  4001 F. Accordingly, the annular handle  4100  is fixed to the camera body  2  by screwing the handle bolt  4003  to the camera bod  2  through the fixing hole  4001   g.    
     The annular handle  4100  improves the strength in the holding-up direction as compared with the case where the handle part  4001  is used independently. Accordingly, when the image pickup apparatus  1  is compact and lightweight, the handle unit  4000  is used independently. When the image pickup apparatus  1  of which the weight becomes heavy because of combination with a large lens is used, the annular handle  4100  is used. Such a separation gives high convenience. 
       FIG.  34 A  is a plan view showing the handle part  4001 E that forms the annular handle viewed in a direction of an arrow V 1  shown in  FIG.  33 A  from a position shown by the arrow V 1 .  FIG.  34 B  is a plan view showing the annular handle  4100  viewed in a direction of an arrow V 2  shown in  FIG.  33 A  from a position shown by the arrow V 2 . 
     As shown in  FIG.  34 A , a center (a position that divides the width into two equally) of the thickness of the grip part  4001   a  of the handle part  4001 E indicated by an arrow T in the X-direction is defined as a center position  4007  shown by an alternate long and short dash line. The fixing holes  4001   g  are provided on the center position  4007 . Then, the rosette  4001   c - 1  facing to the +X side around the through hole  4001   b  (the short-side fastening part  4020 ) of the handle part  4001 E is located on the center position  4007 . Moreover, the rosette  4001   b - 1  facing to the −X side around the through hole  4001   b  (the long-side fastening part  4010 ) of the handle part  4001 E is located on the center position  4007 . 
     Such a configuration of the handle part  4001 E is identical to that of the handle part  4001 F. The center positions  4007  of the handle parts  4001 E and  4001 F are coincident when the annular handle  4100  is formed by combining the handle parts  4001 E and  4001 F of which the rosettes at both the ends are located on the center position  4007  and face to the opposite sides in the width direction. Thereby, the fixing hole  4001   g  of the handle part  4001 E of the lower side (the side of the camera body  2 ) is coincident with the thickness center of the grip part  4001   a  of the handle part  4001 F in the X-direction. Since the grip part  4001   a  of the handle part  4001 F does not shift from the attachment part to the camera body  2  when the annular handle  4100  is attached to the camera body  2 , the handle part  4001 F can be held with sufficient balance. 
       FIG.  35    is a view showing one state where the display panel  4006  is attached to the annular handle  4100 .  FIG.  36 A  is a sectional view showing the annular handle  4100  taken along a line K-K shown in  FIG.  35   . The display panel  4006  is fixed to the long-side fastening part  4010  of the handle part  4001 F, which is one of the connection parts of the handle parts  4001 E and  4001 F of the annular handle  4100 , through the holder component  4002 . The rosette  4002   c - 2  of the holder component  4002  to which the display panel  4006  is fixed is engaged to the rosette  4001   b - 1  at the +X side of the handle part  4001 F, and they are fastened by the fastening bolt  4004  and the fastening nut  4005  in the X-direction. Thereby, the short-side fastening part  4020  of the handle part  4001 E, the long-side fastening part  4010  of the handle part  4001 F, and the holder component  4002  are fastened in the X-direction in this order from the −X side and are fixed firmly. 
     In this state, since the display panel  4006  is in front of the camera body  2  as with the state shown in  FIG.  31   , the user can easily photograph while watching the display panel  4006  when carrying the image pickup apparatus  1  on the shoulder. It should be noted that the display panel  4006  can be fixed to the rosette  4001   c - 2  at the −X side of the short-side fastening part  4020  of the handle part  4001 E of the annular handle  4100  through the holder component  4002 . 
       FIG.  36 B  is a sectional view showing the handle part  4001  taken along a line J-J in  FIG.  33 A . The fastening state by the fastening bolt  4004  and the fastening nut  4005  will be described hereinafter by comparing  FIG.  36 A  and  FIG.  36 B . The fastening bolt  4004  is constituted by a grip part  4004   a  and an external screw part  4004   b . The grip part  4004   a  is a grip for tightening and loosening the fastening bolt  4004  that is screwed to the fastening nut  4005 . The external screw part  4004   b  is cylindrical and is integrally assembled with the grip part  4004   a . The fastening nut  4005  is constituted by a grip part  4005   a  and an internal screw part  4005   b . The grip part  4005   a  is a grip for tightening and loosening the fastening nut  4005  that is screwed to the fastening bolt  4004  and has a hollow part. The internal screw part  4005   b  has an internal screw in a center hole and is integrally assembled with the grip part  4005   a.    
     In  FIG.  36 A , the three members including the handle part  4001 E, the handle part  4001 F, and the holder component  4002  are put between the fastening bolt  4004  and the fastening nut  4005 . The external screw part  4004   b  of the fastening bolt  4004  is screwed with the fastening nut  4005  in a range of a length W 1  in this state. In the meantime, in  FIG.  36 B , the two members including the handle part  4001 E and the handle part  4001 F are put between the fastening bolt  4004  and the fastening nut  4005 . The external screw part  4004   b  of the fastening bolt  4004  is screwed with the fastening nut  4005  in a range of a length W 1 +W 2  in this state. It should be noted that the two members including the handle part  4001  and the holder component  4002  may be put between the fastening bolt  4004  and the fastening nut  4005  as shown in  FIG.  31   . 
     In this way, the fastening bolt  4004  may fix three members or two members when an accessory like the display panel  4006  is attached. Accordingly, the external screw part  4004   b  of the fastening bolt  4004  needs a predetermined length so as to screw to the internal screw part  4005   b  of the fastening nut  4005  even when the three members are put therebetween. In the meantime, the length of the external screw part  4004   b  of the fastening bolt  4004  is determined so that a tip of the external screw part  4004   b  that is screwed with the internal screw part  4005   b  and enters into the hollow part is not projected from the grip part  4005   a . This is because the external screw part  4004   b  of the fastening bolt  4004  is made from metal and the projection of the tip of the external screw part  4004   b  from the fastening nut  4005  is not preferable. 
     Accordingly, the length of the external screw part  4004   b  of the fastening bolt  4004  is determined so as to be sufficient when three members are inserted so as not to be projected from the grip part  4005   a  of the fastening nut  4005  when two members are inserted. Specifically, the length of the fastening nut in the axial direction is ‘W 4 ’ and the length of the portion of the holder component  4002  put between the fastening bolt  4004  and the fastening nut  4005  is ‘W 2 ’. Moreover, when the fastening bolt  4004  is screwed to the fastening nut  4005  by a length W 1  as shown in  FIG.  36 A , firm fastening is obtained. 
     In this case, when the two members including the handle parts  4001 E and  4001 F excluding the holder component  4002  are fastened as shown in  FIG.  36 B , the external screw part  4004   b  of the fastening bolt  4004  proceeds to the side of the fastening nut  4005  by the length W 2 . Accordingly, when the relation of ‘W 1 +W 2 &lt;W 4 ’ is satisfied, a user does not touch the external screw part  4004   b  of the fastening bolt  4004  even when the two members are inserted, which enables safe use. 
     Other Embodiments 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention 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. 2020-094420, filed May 29, 2020, which is hereby incorporated by reference herein in its entirety.