Abstract:
An inner cover supported to be rotatable in a panning direction is urged by an elastic member in a direction approaching a dome. When a shock is applied to a dome cover, the inner cover is pressed in a direction away from the dome and touches a supporting member of a fixing portion. As a result deformation of the dome can be suppressed, and a lens unit and a panning rotation unit can be protected. In addition, since the dome cover is suppressed, it is not required to provide a retraction mechanism in the lens unit. Moreover, since no rigidity of the dome cover is required, the dome cover can be reduced in wall thickness and increased in diameter, so that priority is given to optical performance of the lens unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an image pickup apparatus such as a monitoring camera with shock resistance. 
         [0003]    2. Description of the Related Art 
         [0004]    In some conventional monitoring cameras with shock resistance property, a dome cover for covering a lens unit is made of a material such as shock-resistant polycarbonate resin, and an exterior housing for covering a main body of the camera is made of metal to achieve the shock resistance property. However, as compared with the exterior housing made of metal, the dome cover made of resin may be momentarily deformed to a great extent by a shock, even if the dome cover is not damaged. For this reason, if a shock over a certain energy level is applied to the monitoring camera, the dome cover is deformed by the shock, and the deformed dome cover may contact an inner structure such as the lens unit, resulting in a damage of the inner structure. 
         [0005]    As an example of a conventional technique to solve such an issue, a monitoring camera is discussed in which a rotation base serving as a supporting member supporting a camera unit is fixed with shaft screws, which are each inserted into a vertically extending elongate hole provided in a support of a rotary bracket. In this example, the rotation base can be supported to be rotatable in the vertical direction and linearly movable in the vertical direction with a simple structure, thereby absorbing a shock when a cover is hit, so that damage to the camera unit can be prevented (see Japanese Patent Application Laid-Open No. 2003-174572). 
         [0006]    The conventional monitoring camera with shock resistance property has a structure in which the lens unit is retracted when the dorm cover is deformed by a shock applied to the dome cover, and thus preventing a damage. A deformation amount of the dome cover in receiving a shock depends on the wall thickness and the diameter of a hemispherical shape of the dome cover. The smaller the wall thickness, the greater the deformation amount. The larger the diameter of the hemispherical shape, the greater the deformation amount of the dome cover. 
         [0007]    Further, as the wall thickness is greater, or as the diameter of the hemispherical shape is smaller, an influence exerted by the dome cover on optical performance of the lens unit is greater because the dome cover acts as an optical component. When a lens unit with high-magnification and high-telephoto zoom capabilities is employed, the influence on the optical performance is even greater, which may cause degradation in resolution. Therefore, a monitoring camera equipped with the high-magnification and high-telephoto lens unit is desirably configured in such a manner that the wall of the dome cover is as thin as possible, and that the diameter of the hemispherical shape is large. 
         [0008]    However, in the conventional monitoring camera with shock resistance property, if the dome cover has a thinner wall and a larger diameter, the deformation amount of the dome cover due to a shock increases. This increases the amount of retraction necessary for the lens unit, which leads to an increase of the size of the monitoring camera. 
       SUMMARY OF THE INVENTION 
       [0009]    According to an aspect of the present invention, an image pickup apparatus includes a lens unit including an optical system and an image pickup device, a dome cover covering the lens unit, a rotation base unit configured to support the lens unit, a fixing portion configured to support the rotation base unit while allowing the rotation base unit to rotate in a pan direction, and an inner cover disposed between the lens unit and the dome cover. The inner cover is elastically supported by the rotation base unit, and in a case where the inner cover is pressed, the inner cover moves in a direction away from the dome cover and contacts the fixing portion. 
         [0010]    With such a configuration, when a shock is applied to the dome cover, the inner cover, not the lens unit, contacts the deformed dome cover first. In a state where no external force such as a shock is being applied to the inner cover, the inner cover is separated from the fixing portion by an elastic member. However, in a state where a shock is being applied, the inner cover is pressed by the deformed dome cover, so that the inner cover moves and then contacts the fixing portion. Because of the rigidity of the inner cover interposed between the fixing portion and the dome cover, deformation of the dome cover is suppressed, so that collision with the lens unit can be prevented. 
         [0011]    Further, in the image pickup apparatus according to the aspect of the present invention, the lens unit is supported by the rotation base unit so as to be rotatable in a tilt direction, the inner cover has a hemispherical shape similar to the dome cover, and an elongate hole shape portion provided to avoid shielding a light beam area within a range in which the lens unit rotates in the tilt direction. 
         [0012]    With such a configuration, in the image pickup apparatus in which the lens unit is rotatable in the tilt direction, the inner cover can be disposed between the dome cover and the lens unit without affecting an image pickup range. 
         [0013]    Furthermore, in the image pickup apparatus according to the aspect of the present invention, the inner cover includes resin, and has hollow shape portions facing each other on both sides across the center line of the elongate hole shape in a longitudinal direction, and further has a plurality of reinforcing ribs intersecting with the hollow shape portion in a direction perpendicular to the longitudinal direction. 
         [0014]    With such a configuration, the weight of the inner cover can be reduced without forming the inner cover by using rigid metal or increasing the thickness of resin. Therefore, a load when panning the image pickup apparatus can be reduced. 
         [0015]    As described above, according to the aspect of the present invention, when a shock is applied to the dome cover, the shock is partially received by the inner cover with its rigidity, so that the deformation of the dome cover can be suppressed. Therefore, the deformed dome cover can avoid colliding with the lens unit, thereby causing no damage. In addition, since the deformation of the dome cover is suppressed in the above-described configuration, it is not required to provide a retraction mechanism in the lens unit. Moreover, since the rigidity of the dome cover is not required in the above-described configuration, the dome cover can be reduced in wall thickness and increased in diameter, so that priority can be given to optical performance of the lens unit. 
         [0016]    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 
         [0017]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features and aspects of the present invention and, together with the description, serve to explain the principles of the present invention. 
           [0018]      FIG. 1  is a configuration diagram illustrating an entire image pickup apparatus according to an exemplary embodiment of the present invention. 
           [0019]      FIG. 2  is a configuration diagram illustrating the inside of the image pickup apparatus according to the exemplary embodiment of the present invention. 
           [0020]      FIG. 3  is a diagram illustrating a detailed shape of an inner cover according to the exemplary embodiment of the present invention. 
           [0021]      FIG. 4  is a cross-sectional view illustrating the image pickup apparatus before a shock is applied according to the exemplary embodiment of the present invention. 
           [0022]      FIG. 5  is a cross-sectional view illustrating the image pickup apparatus after a shock is applied according to the exemplary embodiment of the present invention. 
           [0023]      FIG. 6  is a detailed cross-sectional view illustrating the image pickup apparatus before the a shock is applied according to the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0024]    Exemplary embodiments, features and aspects of the present invention will now be described in detail below with reference to the attached drawings. 
         [0025]    An exemplary embodiment of the present invention will be described below, by using a monitoring camera as an example. 
         [0026]      FIG. 1  is a configuration diagram illustrating an entire image pickup apparatus according to the exemplary embodiment of the present invention. A dome component  11  is attached to a cover  12 , so that the dome component  11  and the cover  12  are integrated in to a single unit serving as a dome cover. The cover  12  is attached to a case  13 , and covers an image pickup apparatus  100 . Further, an inner case  14  is attached to the inside of the case  13 . 
         [0027]      FIG. 2  is a configuration diagram illustrating the inside of the image pickup apparatus  100  according to the exemplary embodiment of the present invention. The image pickup apparatus  100  broadly includes a camera unit  200 , a rotation base unit  300 , and a fixing portion unit  400 . 
         [0028]    The camera unit  200  is configured as follows. A lens unit  201  has an optical system such as a lens, and further has an image pickup device such as a charge coupled device (CCD) sensor and a complementary metal oxide semiconductor (CMOS) sensor. The lens unit  201  is supported by a lens frame unit  202  having a tilt rotation shaft. A camera cover  203  for covering the lens unit  201  is attached to the lens frame unit  202 . Further, a tilt pulley  204 , which is provided to drive the camera unit  200  so that the camera unit  200  rotates in a tilt direction, is fixed to the lens frame unit  202 . 
         [0029]    The rotation base unit  300  is configured as follows. A rotation base  301  supports the camera unit  200 , while allowing the camera unit  200  to rotate in the tilt direction. A tilt motor  302  drives the tilt pulley  204  by using a timing belt, so that the camera unit  200  can be rotated in the tilt direction. A control board  303  is fixed to the rotation base  301 . Further, a pan motor (not illustrated) is attached to the rotation base  301 . The pan motor rotationally drives the camera unit  200  in a pan direction. 
         [0030]    An inner cover  310  is elastically supported by the rotation base  301  so as to cover the camera unit  200 . The rotation base  301  includes spring receiving portions  301   a  and stepped screw fixing bosses  301   b . The spring receiving portions  301   a  is disposed facing each other across the camera unit  200  located at the midpoint therebetween. Each of the stepped screw fixing bosses  301   b  is disposed likewise. The inner cover  310  is urged by springs  311  in a direction approaching the dome component  11 . The inner cover  310  is supported to be movable in a direction away from the dome component  11  by inserting and fixing the stepped screws  312  into aperture portions  310   b  illustrated in  FIG. 3 . Further, the inner cover  310  has a substantially hemispherical shape similar to the shape of the dome component  11 . The inner cover  310  is elastically supported by the rotation base  301  so as to be disposed in a space between the camera unit  200  and the dome component  11 . 
         [0031]      FIG. 3  is a diagram illustrating a detailed shape of the inner cover  310  according to the present exemplary embodiment. In a range in which the camera unit  200  rotates in the tilt direction, the inner cover  310  has an elongate hole shape portion  310   a  provided to avoid shielding a light beam area where the lens unit  201  can capture an image. However, because of the elongate hole shape  310 , the inner cover  310  has lower strength than that of the dome component  11  if the inner cover  310  is made of the same material and has the same wall thickness as those of the dome component  11 . 
         [0032]    In a case where the inner cover  310  is made of a metallic material to increase the strength, the weight and the rotational inertia of the inner cover  310  increase, resulting in a large load in rotating the rotation base  301  in the pan direction. Therefore, the rotation base  301  cannot be driven to rotate with high speed and acceleration, or large driving power is necessary. In a case where the inner cover  310  is made of a resin material and the wall thickness of the inner cover  310  is increased to enhance the strength, a similar problem arises in this case as well. 
         [0033]    To improve the strength of the inner cover  310 , it is effective to provide a tall reinforcing rib in a direction perpendicular to a longitudinal direction of the elongate hole shape portion  310   a . However, the sidewall depth of the inner cover  301  is deep because of its substantially hemispherical shape, so that a thin rib would be formed considering a draft angle at the time of molding. Therefore, the inner cover  310  according to the present exemplary embodiment has hollow shape portions  310   c . The hollow shape portions  310   c  are faces each other on both sides across the center line of the elongate hole shape portion  310   a  in the longitudinal direction. Reinforcing ribs are provided, namely reinforcing ribs  310   d  provided on the convex side of the hemispherical shape, and reinforcing ribs  310   e  and  310   f  provided separately on the concave side of the hemispherical shape. Each of the reinforcing ribs has a shape connecting to or intersecting with the hollow shape portions  310   c.    
         [0034]    With such a configuration, the sidewall depth can decreases, and reinforcing ribs substantially maintaining the wall thickness can be provided. Therefore, even if the inner cover  310  is made of a resin material, the strength can be increased. Further, the inner cover  310  can be provided as a shock-resistant component superior to the dome component  11  in terms of strength, by employing high-rigidity resin containing fiberglass or carbon filler for the resin material. 
         [0035]    The fixing portion unit  400  is configured as follows. A panning bearing unit  401  supports the rotation base unit  300 , so that the rotation base unit  300  can rotate in the pan direction. Further, a panning pulley  304  is fixed to the panning bearing unit  401 . When the panning pulley  304  is driven by the pan motor using a timing belt, the rotation base unit  300  can rotate in the pan direction. A fixed metal plate  402  supports the panning bearing unit  401 , and is fixed to the case  13 . 
         [0036]      FIGS. 4 and 6  are cross-sectional views illustrating the image pickup apparatus before a shock is applied to the image pickup apparatus, and  FIG. 5  is a cross-sectional view illustrating the image pickup apparatus after the shock is applied to the image pickup apparatus.  FIG. 6  illustrates an expanded view of a part where the inner cover  310  is to contact the inner case  14 . Before a shock is applied to the image pickup apparatus, the inner cover  310  maintains a predetermined gap relative to the inner case  14  disposed in the fixing portion unit  400 , and the inner cover  310  is held in the space between the dome component  11  and the camera unit  200 . By maintaining the predetermined gap relative to the inner case  14 , the inner cover  310  does not generate a friction, which leads to a load in a movement in the pan direction. 
         [0037]    After the shock has been applied to the image pickup apparatus, the inner cover  310  is pressed by the deformed dome component  11 , moves in the direction away from the dome component  11 , and contacts the inner case  14 . The inner cover  310  interposed between the dome component  11  and the inner case  14  has sufficient strength against the shock, and thus is substantially free from deforming. As a result, the deformation of the dome component  11  can be also suppressed. In addition, after ending the influence of the shock, the inner cover  310  returns to the position before the application of the shock, with elasticity of the springs  311 . 
         [0038]    In addition, a configuration may be applicable in which the reinforcing rib  310   e , which forms a part of the inner cover  310 , can contact the inner case  14  when the inner case  14  receives the shock. 
         [0039]    It is also conceivable to provide such a configuration that the inner cover  310  is immovably fixed relative to the rotation base unit  300 , and the rotation base unit  300  receives a shock. In this case, the panning bearing unit  401  and the fixed metal plate  402  receive the shock. Therefore, there is such a concern that a bearing (not illustrated) in the panning bearing unit  401  may be damaged, and that the fixed metal plate  402  may be deformed. 
         [0040]    The case  13  is made of a material having sufficient strength, such as metal. The inner case  14  is firmly fixed to the case  13 , and thus is almost unlikely to be deformed by the shock applied to the inner cover  310 . Further, in the present exemplary embodiment, the inner cover  310  is configured to be able to contact the inner case  14 . However, the inner cover  310  may be configured to be able to contact the case  13 . 
         [0041]    The present invention has been described above in detail based on the exemplary embodiment. However, the present invention is not limited to such a specific exemplary embodiment, and includes various modifications in a scope not deviating from the gist of the present invention. Parts of the above-described exemplary embodiment may be combined as appropriate. 
         [0042]    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. 
         [0043]    This application claims the benefit of Japanese Patent Application No. 2014-219765, filed Oct. 28, 2014, which is hereby incorporated by reference herein in its entirety.