Abstract:
A first heat radiation unit is formed on one surface of the imaging unit in a vertical direction. A second heat radiation unit is formed on the other surface of the imaging unit in the vertical direction. A third heat radiation unit is formed on a surface opposite to an imaging direction of the imaging unit. A first heat transfer unit transfers heat of a first heat source of the imaging unit to the first heat radiation unit and the third heat radiation unit. A second heat transfer unit transfers heat of a second heat source of the imaging unit, which has a higher maximum allowable temperature than the first heating unit, to the second heat radiation unit. A heat insulation unit suppresses heat transfer between the first and the second heat radiation units and between the third and the second heat radiation units.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims the benefit of Japanese Patent Application No. 2012-287284, filed on Dec. 28, 2012, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an imaging device, and more particularly, an imaging device including a heat radiation unit that radiates internal heat 
         [0004]    2. Description of the Related Art 
         [0005]    Imaging devices are known to include a heat radiation unit in order to prevent an increase in temperature due to heat generation of a circuit or a component within the imaging device (for example, refer to Patent Document 1). 
         [0006]    A video camera disclosed in Patent Document 1 transfers heat from a substrate  5  and a substrate  6 , which are heating units of the video camera, to right and left side panels of a case, and performs heat radiation from the right and left side panels. 
         [0007]    Here, examples of a primary heating unit of the video camera may include an image processing unit such as an application specific integrated circuit (ASIC) or a digital signal processor (DSP) that processes a signal, and an imaging element such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. In general, the image processing unit generates a large amount of heat, The imaging element does not generate a large amount of heat, but a maximum allowable temperature which can function as the element is low, Therefore, the performance or lifespan of the imaging element may deteriorate due to an excessive increase in temperature. 
         [0008]    However, the video camera disclosed in Patent Document 1 uses the right and left side panels that are symmetrical to each other, and does not change the size or arrangement of the side panels in accordance with the features of the heating units. That is, the video camera does not consider such features of the heating unit with regard to cooling. Therefore, there is a problem in that it is difficult to appropriately perform heat radiation according to the features of the heating units. 
         [0009]    (Patent Document 1) Japanese Laid-Open Patent Publication No. 2012-169875 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention provides a technique capable of appropriately performing heat radiation according to features of heating units of an imaging device. 
         [0011]    In order to solve the above-mentioned problem, the present invention provides the following device. 
         [0012]    An imaging device including an imaging unit  10  that includes a first heat source  104  and a second heat source  102  having a higher maximum allowable temperature than the first heat source and performs imaging, a transparent cover  70  that covers the imaging unit, a tilting driving unit  40  that drives the imaging unit in a tilting direction, a panning driving unit  50  that drives the imaging unit in a panning direction, a first heat radiation unit  302  that is formed on one surface of the imaging unit in a direction, which is perpendicular to an imaging direction and a rotation axis of the tilting driving unit, and whose an exposed portion has a contour of a substantially spherical surface shape about an intersection point between the rotation axis of the tilting driving unit and a rotation axis of the panning driving unit, a second heat radiation unit  301  that is formed on the other surface of the imaging unit in a direction, which is perpendicular to the imaging direction and the rotation axis of the tilting driving unit, and whose an exposed portion has a contour of a substantially spherical surface shape about the intersection point between the rotation axis of the tilting driving unit and the rotation axis of the panning driving unit, a third heat radiation unit  303  that is formed on a rear surface of the imaging unit when the imaging direction is set to a front, and whose an exposed portion has a contour of a substantially spherical surface shape about the intersection point between the rotation axis of the tilting driving unit and the rotation axis of the panning driving unit, a first heat transfer unit  110  that transfers heat of the first heat source to the first heat radiation unit and the third heat radiation unit, a second heat transfer unit  108  that transfers heat of the second heat source to the second heat radiation unit, and a heat insulation unit  112  that suppresses heat transfer between the first and the second heat radiation units and between the third and the second heat radiation units. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0014]      FIG. 1  is a diagram illustrating an appearance of a domed camera which is an embodiment of an imaging device of the present invention; 
           [0015]      FIG. 2  is a configuration diagram of a camera module that is used in the domed camera; 
           [0016]      FIG. 3  is a perspective view illustrating configurations of the camera module, a front plate, and a rear plate; 
           [0017]      FIGS. 4A and 4B  are perspective views illustrating configurations of the camera module, a front bracket, and a rear bracket; 
           [0018]      FIG. 5  is a perspective view illustrating configurations of the camera module and an upper heat sink; 
           [0019]      FIG. 6  is a perspective view illustrating configurations of the camera module, a lower heat sink, and a rear heat sink; 
           [0020]      FIG. 7  is a side view illustrating a flow of heat radiation of the camera module; 
           [0021]      FIG. 8  is a cross-sectional view illustrating a configuration of the domed camera; 
           [0022]      FIGS. 9A and 9B  are perspective views illustrating configurations of a duct cover and a fan bracket of the domed camera; and 
           [0023]      FIG. 10  is a cross-sectional view illustrating a flow of air within the domed era. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Hereinafter, a domed camera, which is an embodiment of an imaging device of the present invention, will be described in detail with reference to the accompanying drawings. However, components, types, combinations, shapes, relative arrangement of the components, and the like are not meant to limit a scope of the invention thereto but are simple examples of explanation unless specifically described otherwise. In addition, the same portions and matters are denoted by the same reference numerals and signs, and repeated descriptions thereof will be omitted. 
         [0025]    &lt;Configuration&gt; 
         [0026]    As illustrated in  FIG. 1 , a domed camera  1  of the present embodiment includes a case portion  60 , a domed cover  70  that is transparent or translucent, and a camera module  10  that is provided within the domed cover  70 . When the domed camera  1  is actually attached to a ceiling, the domed camera in a state illustrated in  FIG. 1  is turned upside down and is then attached to the ceiling. However, for convenience of description, the domed camera in a direction illustrated in  FIGS. 1  will be described. As illustrated in  FIG. 2 , the camera module  10  includes a lens  101  that acquires an optical image, a CMOS image sensor  104  that generates an image signal by performing photoelectric conversion of the optical image that is acquired by the lens  101 , a DSP  102  that performs image processing on the image signal that is generated by the CMOS image sensor  104 , a DSP substrate  103  on which the DSP  102  is mounted, a heat transfer member  105  that transfers heat of the DSP  102 , a CMOS substrate  106  on which the CMOS image sensor  104  is mounted, a heat transfer member  107  that transfers heat of the CMOS substrate  106 , and a cover  108  that protects the camera module  10 . Since one surface of the heat transfer member  105  comes into contact with the DSP  102  and the other surface thereof conies into contact with the cover  108 , the heat of the DSP  102  is transferred to the cover  108  through the heat transfer member  105 . 
         [0027]    Since one surface of the heat transfer member  107  comes into contact with the CMOS substrate  106  and the other surface thereof comes into contact with a rear plate  110  to be described below, the heat of the CMOS image sensor  104  is transferred to the rear plate  110  through the CMOS substrate  106  and the heat transfer member  107 . 
         [0028]    When an imaging direction, that is a direction including the lens  101 , is set as a front direction of the camera module  10 , a front plate  109  is attached to the front of the cover  108  as illustrated in  FIG. 3 . In addition, the rear plate  110  is attached to two right and left positions of the rear of the cover  108 , with an insulation sheet  112  interposed therebetween, wherein the insulation sheet is formed of a resin material such as polyethylene terephthalate (PET) and has low heat conductivity. Heat transfer between the rear plate  110  and the cover  108  is suppressed by the insulation sheet  112 , The rear plate  110  includes two protrusion portions  110   a,  which protrude in the downward direction of the camera module in  FIG. 3 , at right and left positions thereof. Two screw holes  110   b  are formed on a rear surface of the rear plate  110 . In addition, a concave portion  110   c  having a circular shape about the optical axis  111  is formed in the rear plate  110 . 
         [0029]      FIG. 4A  is a perspective view of he camera module  10  that is obliquely seen from the rear of the camera module  10 .  FIG. 48  is a perspective view of the camera module  10  that is obliquely seen from the front of the camera module  10 . Both  FIGS. 4A and 4B  show a state where the front plate  109 , the rear plate  110 , a front bracket  201 , and a rear bracket  203  are attached to the camera module  10 . 
         [0030]    Concave portions  109   a,    109   b,  and  109   c  having a circular shape are formed on the circumference of the same circle about the optical axis  111  on a front surface of the front plate  109 . The L-shaped front bracket  201  is attached to the camera module so as to cover a front surface and a right side surface of the camera module  10 . Arc-like elongate holes  201   a,    201   b,  and  201   c  are formed in the front bracket  201  about the optical axis  111  so as to correspond to the concave portions  109   a,    109   b,  and  109   c.  The elongate holes  201   a,    201   b,  and  201   c  are coupled to the concave portions  109   a,    109   b,  and  109   c.  Thus, the front bracket  201  is configured to be rotatable about the optical axis  111 . A tilting rotation axis  202  is also formed in the front bracket  201 . The tilting rotation axis  202  is an axis for rotating the camera module  10  in a tilting direction. In addition, the front bracket  201  and the front plate  109  are coupled to each other by using a screw  205  having step flange so as not to be disengaged from each other. 
         [0031]    In addition, as illustrated in  FIG. 4A , the L-shaped rear bracket  203  is attached to the camera module so as to cover a rear surface and a left side surface of the camera module  10 . A circular hole  203   a  coupled to the concave portion  110   c  of the rear plate  110  is formed in the rear bracket  203 . In addition, although not shown in the drawing, two arc-like elongate holes are formed in the rear bracket  203  about the optical axis  111  so as to correspond to the screw hole  110   b  that is formed in the rear plate  110 . Then, screws  204   a  and  204   b  are coupled to the screw hole  110   b  through the two elongate holes, thereby fixing the rear bracket  203 . Since the concave portion  110   c  and the circular hole  203   a  are coupled to each other, the rear bracket  203  is configured to be rotatable about the optical axis  111  when the screws  204   a  and  204   b  are loosened. In addition, a tilting driving motor  401  to be described below is attached to a portion which is on the reverse side of the rear bracket  203  in  FIGS. 4A and 4B . Both the front bracket  201  and the rear bracket  203  are an L-shaped bracket as described above, and together constitute a quadrangular shape in which the front bracket and the rear bracket cover the camera module  10  by fixed to each other via screws at two positions. 
         [0032]    When an upper direction in  FIG. 5  is set as an upper direction of the camera module, an upper heat sink  301  is fixed to a top portion of the cover  108  by using a screw (not shown) as illustrated in  FIG. 5 . As illustrated in  FIG. 6 , a lower heat sink  302  is fixed to the two protrusion portions  110   a  of the rear plate  110 , which protrude from a lower surface of the camera module  10 , by using screws. An insulation sheet, which is not shown in the drawing, is interposed between the lower heat sink  302  and the camera module  10 , and the lower heat sink  302  is fixed to the camera module  10  by using a screw. A rear heat sink  303  is fixed to the rear bracket  203  provided on a rear surface of the camera module  10  by using a screw. Gaps are formed between the rear heat sink  303 , the upper heat sink  301 , and the lower heat sink  302  so as not to allow heat transfer therebetween. 
         [0033]    An appearance of each of the upper heat sink  301 , the lower heat sink  302 , and the rear heat sink  303  is configured to have an approximately spherical shape about a rotation center of panning and tilting of the camera module  10  which will be described below. 
         [0034]    As described above, the heat of the DSP  102  of the camera module  10  is transferred to the top surface of the cover  108  through the heat transfer member  105 , and the heat of the CMOS image sensor  104  is transferred to the rear bracket  203 , which is fixed to the rear plate  110 , through the CMOS substrate  106 , the heat transfer member  107 , and the rear plate  110 . 
         [0035]    Therefore, as illustrated in a side view of  FIG. 7 , the heat of the DSP  102  is transferred to the upper heat sink  301  through the cover  108  above the camera module  10  as indicated by an arrow A, and is then radiated to the outside. The heat of the CMOS image sensor  104  is transferred to the rear heat sink  303  from the rear bracket  203  behind the camera module  10  as indicated by an arrow B, and is then radiated to the outside and is also transferred to the lower heat sink  302  from the protrusion portion  110   a  of the rear plate  110  below the camera module  10  as indicated by an arrow C, and is then radiated to the outside from the lower heat sink  302 . 
         [0036]    Since heat transfer between the cover  108  and the rear plate  110  is suppressed by the insulation sheet  112 , heat transfer between the upper heat sink  301  and the lower heat sink  302  and between the upper heat sink  301  and the rear heat sinks  303  is suppressed. 
         [0037]    As illustrated in a configuration diagram of the domed camera  1  of  FIG. 8 , the case portion  60  includes a case outer circumferential portion  60   a  having a cylindrical shape, and a case upper surface portion  60   b.  In addition, a case base  606  is attached to a bottom of the case portion  60 . When the domed camera  1  is attached to a ceiling, the case base  606  is attached to the ceiling and is then coupled to the case portion  60 , thereby allowing the domed camera  1  to be detachably attached to the ceiling. A panning driving motor  50  is attached to the case upper surface portion  60   b.  A panning/tilting driving unit  40  is attached to a to surface of the panning driving motor  50 , and is rotatably driver) in a panning direction by the panning driving motor  50 . The panning/tilting driving unit  40  includes a tilting driving motor  401 . The tilting driving motor  401  holds the rear bracket  203 , and the panning/tilting driving unit  40  holds the tilting rotation axis  202 , and thus the camera module  10  is held by the panning/tilting driving unit  40 . Since the tilting driving motor  401  is located at a position which is on the reverse side of the camera module  10  in  FIG. 8 , the tilting driving motor is shown as a dashed line in  FIG. 8 . 
         [0038]    The panning driving motor  50  rotates the panning/tilting driving unit  40 , and thus the camera module  10  rotates in a panning direction, thereby allowing an imaging direction to be changed to the panning direction. In addition, the tilting driving motor  401  rotates the camera module  10 , and thus the imaging direction may be changed to the tilting direction. 
         [0039]    Meanwhile, a fan bracket  602  and a duct cover  601  are attached to the case base  606  at the bottom of the case portion  60 .  FIG. 9A  illustrates a state where the fan bracket  602  is attached to the case base  606 . A fan  605  for circulating air within the domed camera  1  is attached to the fan bracket  602 . 
         [0040]      FIG. 9B  illustrates a state where the duct cover  601  is additionally attached to the top of the case base  606  to which the fan bracket  602 , illustrated in  FIG. 9A , is attached. As illustrated in  FIG. 9B , the duct cover  601  is provided with an air-blowing duct  603  for discharging air, which is sent by the fan  605 , to the inside of the domed cover  70  by passing through the case upper portion  60   b,  and an upper inhalation duct  604   a  ( 604   a   1 ,  604   a   2 ,  604   a   3 , and  604   a   4 ) that inhales the air from the inside of the domed cover  70 . 
         [0041]    The air-blowing duct  603  and the upper inhalation duct  604   a  are formed along an inner circumference of the domed cover  70 . In addition, at least one of the air-blowing duct  603  and the upper inhalation duct  604   a  is constituted by a plurality of ducts along the inner circumference of the domed cover  70 . In the present embodiment, the upper inhalation duct  604   a  is constituted by a plurality of (four) ducts along the inner circumference of the domed cover  70 . 
         [0042]    When the duct cover  601  is superposed on the fan bracket  602 , the air-blowing duct  603  is formed immediately on the fan  605 . In addition, in the fan bracket  602 , an inhalation groove  604   b  is formed to correspond to the upper inhalation duct  604   a,  and the inhalation duct  604  is formed by the upper inhalation duct  604   a  and the inhalation groove  604   b.  In this manner, the case base  606  to which the duct cover  601  and the fan bracket  602  are attached is attached to the bottom of the case portion  60 . 
         [0043]    In addition, although not shown in the drawing, the case portion  60  is provided with a slip ring for exchanging a signal with the camera module  10 , a circuit board for controlling the camera module  10  or supplying power, and so on. 
         [0044]    &lt;Heat Radiation of Domed Camera  10 &gt; 
         [0045]    Arrows illustrated in  FIG. 10  indicate a flow of air. As illustrated in  FIG. 10 , air that is discharged to the inside of the domed cover  70  from the air-blowing duct  603  is transferred upwards in  FIG. 10  along an inner wall of the domed cover  70 , and reaches a head portion of the domed cover  70 . Then the air is transferred downwards in  FIG. 10  along the inner wall of the domed cover  70  and is inhaled into the inhalation duct  604  As illustrated in  FIGS. 9A and 9B , since the plurality of upper inhalation ducts  604   a  are formed along the inner circumference of the domed cover  70 , the air discharged into the domed cover  70  from the air-blowing duct  603  further spreads in a circumferential direction along the inner circumference of the domed cover  70  and is then inhaled into the inhalation duct  604 . Thus, the air is widely circulated within the domed cover  70 . 
         [0046]    The air inhaled into the inhalation duct  604  passes between the duct cover  601  and the fan bracket  602  and is then transferred to the fan  605  again. 
         [0047]    Therefore, the air is circulated between the inside of the domed cover  70  and a space surrounded by the duct cover  601  and the fan bracket  602  by the fan  605 , and thus the air is never mixed with external air. For this reason, since external dust is not introduced into domed camera  1 , imaging is not obstructed. In addition, when the domed camera  1  is attached to the ceiling or the like, the head portion (a spherical tip) of the domed cover  70  is located at the lowest position, and thus the temperature of the domed camera decreases. However, since air in the head portion may be circulated, heat radiation may be effectively performed. 
         [0048]    Since the air circulating within the domed cover  70  flows along an inner surface of the domed cover  70 , the air comes into contact with the upper heat sink  301 , the lower heat, sink  302 , and the rear heat sink  303  which have an approximately spherical shape. Thus, the heat sinks are cooled. The heat of the DSP  102  is radiated from the upper heat sink  301 . The heat of the CMOS image sensor  104  is radiated from both the rear heat sink  303  and the lower heat sink  302 . In this manner, since the heat of the CMOS image sensor  104  is radiated from two heat sinks, the heat of the CMOS image sensor  104  is radiated from the heat sink having a wider surface area than the DSP  102 , therefore heat radiation of the CMOS image sensor  104  may be sufficiently performed. In addition, the heat sink used for the heat radiation of the CMOS image sensor  104  and the heat sink used for the heat radiation of the DSP  102  are configured as different members, and mutual heat transfer is suppressed. Thus, even if the temperature of the upper heat sink  301  increases due to heat radiation of the DSP  102 , the heat radiation of the CMOS image sensor  104  is not obstructed. 
         [0049]    When the heat sink is located in the vicinity of the case upper portion  60   b,  there is a concern that the flow rate of the air coming into contact with the heat sink may be decreased. However, in the present embodiment, the heat radiation of the CMOS image sensor  104  is performed at two positions, that is, the rear side and the lower side of the camera module  10 . For this reason, when rotation is performed in a tilting direction, even though one heat sink is located in the vicinity of the case upper portion  60   b  where air does not flow smoothly, the other heat sink is located at a position where air flows smoothly. In this manner, the heat radiation of the CMOS image sensor  104  may be sufficiently performed without regard to an angle of tilting. With such a configuration, the temperature of the CMOS image sensor  104  may be decreased further than the DSP  102 . 
         [0050]    In addition, each heat sink is configured to have an approximately spherical shape about a rotation center of panning and tilting of the camera module  10 . For this reason, even though the imaging direction of the camera module  10  is changed by performing panning and tilting, a state of heat radiation does not change significantly, thereby allowing heat radiation to be stably performed. 
         [0051]    &lt;Rotation Adjustment&gt; 
         [0052]    As described above, the front bracket  201  and the rear bracket  203  are attached to the rear plate  110  from the rear of the camera module  10  by using two screws  204 . For this reason, the camera module  10  may be rotated with respect to the front bracket  201  and the rear bracket  203  about the optical axis  111  of the camera module  10  by loosening the two screws  204 . 
         [0053]    The camera module  10  may be inclined in a direction in which the camera module  10  rotates about the optical axis in accordance with component accuracy and assembling accuracy. As a result, a captured image may be inclined. The domed camera  1  of the present embodiment rotates the camera module  10  by loosening the screws  204  for fixing the rear bracket  203 , thereby allowing a gradient of the captured image to be corrected. In addition, since the screws may be operated from the rear of the camera module  10 , which is at the side opposite to the lens  101 , and the adjustment may be performed while not obstructing the imaging and viewing the captured image. 
         [0054]    In addition, in the present embodiment, although an example has been described in which a plurality of heating units having different maximum allowable temperatures are cooled, heating units having different features may be used. For example, the present invention may be applied to a case of including a plurality of heating units having significantly different amounts of heat generation or a case where an amount of heat generation of one of plurality of heating units significantly varies. 
         [0055]    According to an imaging device of the present invention, heat radiation can be appropriately performed according to features of a heating unit of the imaging device. 
         [0056]    While this invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.