Abstract:
A camera apparatus comprising an image pickup device, a lens cover which has an end plate comprising a first plate with a through hole and a second plate positioned in the through hole, and a lens which is covered by the lens cover and converges light from an object to the image pickup device, the light passing through the end plate. A plurality of light sources are arranged to surround the lens in the lens cover and a light shielding member is arranged between the lens and the light sources, and bridges a gap between the first plate and the second plate.

Description:
CROSS-REFERENCE RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. application Ser. No. 13/552,995 filed Jul. 19, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a camera apparatus including a light shielding member provided at a lens cover. 
         [0004]    2. Background Art 
         [0005]    Some of surveillance cameras use infrared light having permeability or spectral characteristics superior to visible light. In the type of the surveillance camera, in order to prevent the infrared light of an infrared light source arranged around a lens from being incident on an optical system directly, a light shielding member is provided at a lens cover. JP-B-3988051 discloses an imaging apparatus, which is an example of a technique to provide a light shielding plate on a lens hood. 
         [0006]      FIGS. 9A and 9B  shows the surveillance camera of the related art which shields infrared light with a light shielding member. The surveillance camera includes an image pickup device  101 , a lens  102  which converges light from an object to the image pickup device  101 , and a circular coaxial lens cover  103  which has the lens  102  inside thereof. In the lens cover  103 , a plurality of infrared light sources  104  are annularly arranged to surround the lens  102 . A planar or cylindrical light shielding member  105  having a circular opening shape is provided between the lens  102  and the infrared light source  104 . Since the light shielding member  105  is provided, the infrared light can be suppressed to incident on the lens  102  without passing through the object from the infrared light source  104 . 
       SUMMARY 
       [0007]    However, when the light shielding member  105  is circular shape, a vignetting occurs in a diagonal direction of an angle of view. In a case of the light shielding member  105  having a circular shape, a horizontal angle of view is limited to about 80 degree to obtain an image without the vignetting. Accordingly, in a case where the light shielding member  105  is the circular shape, in order to obtain wider angle of view of the lens, it is necessary to increase the diameter of the light shielding member  105 . As a result, the whole of the light shielding member  105  becomes large in the diameter, and the cross section of a product becomes large. 
         [0008]    The present invention was made in view of the above-described circumstances, and an object thereof is to provide a camera apparatus capable of obtaining the wide angle image without increasing the size of the apparatus. 
         [0009]    An aspect of the invention provides a camera apparatus including: an image pickup device; a lens configured to converge light from an object to the image pickup device; a coaxial circular-shaped lens cover in which the lens is arranged; a plurality of infrared light sources arranged to surround the lens in the lens cover; and a light shielding member which is provided between the lens and the infrared light source and which has an opening, wherein the opening is outwardly extended at corner optical path portions which correspond to diagonal corners of an angle of view of the image pickup device. 
         [0010]    According to the camera apparatus of the aspect, the product can be decreased in size while obtaining the wide angle image without vignetting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a surveillance camera of an embodiment according to the invention; 
           [0012]      FIG. 2  is an exploded perspective view of the surveillance camera illustrated in  FIG. 1 ; 
           [0013]      FIG. 3A  is a cross-sectional view of a lens cover portion including an optical axis thereof illustrated in  FIG. 2 , and  FIG. 3B  is a front view thereof; 
           [0014]      FIG. 4A  is a perspective view of the lens cover with cutaway a portion thereof, and  FIG. 4B  is a front view of a cutaway surface thereof; 
           [0015]      FIG. 5A  is a front view of a light shielding member having an opening shape in a triangular bulging-shaped portion,  FIG. 5B  is a front view of a light shielding member having an opening shape similar to a light flux corresponding to an angle of view,  FIG. 5C  is a front view of a light shielding member having an opening shape of a rectangular shape, and  FIG. 5D  is a front view of a light shielding member having an opening shape in a half oval-shaped portion; 
           [0016]      FIG. 6A  is a perspective view in the vicinity of a lens representing an optical path corresponding to the angle of view,  FIG. 6B  is a perspective view in the vicinity of a lens including a light shielding member of an embodiment, and  FIG. 6C  is a perspective view in the vicinity of a lens including a light shielding member of a comparative example; 
           [0017]      FIG. 7A  is a front view of  FIG. 6C , and  FIG. 7B  is a front view of an image obtained by the light shielding member; 
           [0018]      FIG. 8A  is a front view of  FIG. 6B , and  FIG. 8B  is a front view of an image obtained by the light shielding member; and 
           [0019]      FIG. 9A  is a cross-sectional view of a lens cover portion of the related art including an optical axis thereof, and  FIG. 9B  is a front view thereof. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Hereinafter, embodiments of the invention are described with reference to drawings. 
         [0021]      FIG. 1  is a perspective view of a surveillance camera which serves as a camera apparatus of an embodiment according to the invention. 
         [0022]    A surveillance camera  11  of the embodiment is covered by a cover case  15  including a front cover  12 , a main body cover  13  and a rear cover  14 . The cover case  15  is further covered by a top plate  16  at an upper portion thereof. In the surveillance camera  11 , a mounting seat  17  is provided at the location of the main body cover  13 , and the mounting seat  17  is fixed at a support which meets a CD including a female LAN terminal (not shown). 
         [0023]      FIG. 2  is an exploded perspective view of the surveillance camera  11  illustrated in  FIG. 1 . 
         [0024]    In the main body cover  13 , a seal frame material  18 , a heat sink  19 , a rear surface pressing plate  20  and an operation portion cover  21  are accommodated. In the operation portion cover  21 , an image pickup device  22  is accommodated. In the image pickup device  22 , a cylindrical lens seat  23  is provided, and the lens seat  23  accommodates therein a lens  24 . The lens  24  converges light from the object to the image pickup device  22 . 
         [0025]    At an outer periphery of the lens seat  23 , an annular light source mounting board  25  is inserted from outside. At the light source mounting board  25 , an annular infrared light source  26  is mounted. In the embodiment, the infrared light source  26  includes an annular LED light emitting portion  28  in which a plurality of LEDs  27  are arranged in a circumferential direction. As the infrared light source  26 , a light source other than the LED may be used. 
         [0026]    The outside of the annular LED light emitting portion  28  is covered by a lens cover  29 . The lens cover  29  is accommodated in the front cover  12 . The lens cover  29  is formed in a coaxial circular shape and includes therein the annular LED light emitting portion  28  and the lens  24 . In other words, the infrared light source  26  surrounds the lens  24  at the inside of the lens cover  29  and is annularly arranged. A light shielding member  30  is provided between the lens  24  and the annular LED light emitting portion  28 . 
         [0027]      FIG. 3A  is a cross-sectional view of a lens cover portion illustrated in  FIG. 2  including an optical axis thereof,  FIG. 3B  is a front view thereof,  FIG. 4A  is a perspective view of the lens cover  29  with cutaway a portion thereof and  FIG. 4B  is a front view of a cutaway surface thereof. 
         [0028]    As shown in  FIG. 4A , the light shielding member  30  is coaxially mounted to a circular end plate  31  which closes one axial end of the lens cover  29 . The circular end plate  31  of the lens cover  29  is formed by a member which transmits at least the infrared light. As shown in  FIG. 4B , at the circular end plate  31 , a light shielding member mounting hole  32 , in which the light shielding member  30  penetrates and is assembled, is formed. The light shielding member  30  is inserted into the light shielding member mounting hole  32 . A rear end of the light shielding member  30 , which is mounted in the light shielding member mounting hole  32 , is fitted and fixed in a concave portion  33  of the light source mounting board  25 . In other words, a front end of the light shielding member  30  is fixed in the light shielding member mounting hole  32 , and the rear end thereof is fixed to the light source mounting board  25 . The lens  24  fixed at the lens seat  23  is arranged an inside of the light shielding member  30 . In addition, a front opening portion  34  of the light shielding member  30  is covered by a cover member  35  which transmits at least the infrared light. The cover member  35  is separated from the circular end plate  31 . 
         [0029]      FIG. 5A  is a front view of a light shielding member  30  having an opening shape in a triangular bulging-shaped portion  36 ,  FIG. 5B  is a front view of a light shielding member  42  having an opening shape similar to a light flux  37  (see  FIG. 6A ,  FIG. 6B  and  FIG. 6C ) corresponding to an angle of view,  FIG. 5C  is a front view of a light shielding member  44  having an opening shape of a rectangular shape and  FIG. 5D  is a front view of a light shielding member  45  having an opening shape in a half oval-shaped portion  38 . 
         [0030]    The light shielding member  30  has an opening shape which outwardly extends at a diagonal corner corresponding optical path portion  39  (hereinafter referred to as a corner optical path portion  39 ) corresponding to the diagonal corners of the angle of view in the image pickup device  22 . In the embodiment, as shown in  FIG. 5A , the light shielding member  30  is configured such that the opening shape thereof has the triangular bulging-shaped portion  36  which outwardly protrudes from a circular opening shape portion  40  at a position corresponding to the corner optical path portion  39 . Accordingly, in the embodiment, while the circular opening shape portion  40  of the light shielding member  30  is not changed from a shape of the related art, only the triangular bulging-shaped portion  36  protruding from the circular opening shape portion  40  is formed to avoid the corner optical path portion  39  which protrudes outwardly. With this configuration, it is not necessary to largely change the location of the infrared light source  26  from the related art. 
         [0031]    Next, the function of the surveillance camera  11  having the configuration described above is described while comparing with a comparative example. 
         [0032]      FIG. 6A  is a perspective view in the vicinity of a lens representing an optical path corresponding to the angle of view,  FIG. 6B  is a perspective view in the vicinity of a lens including a light shielding member  30  of an embodiment,  FIG. 6C  is a perspective view in the vicinity of a lens including a light shielding member  105  of a comparative example,  FIG. 7A  is a front view of  FIG. 6C ,  FIG. 7B  is a front view of an image obtained by the light shielding member,  FIG. 8A  is a front view of  FIG. 6B ,  FIG. 8B  is a front view of an image obtained by the light shielding member. 
         [0033]    As shown in  FIG. 6A , in a case where the light passing through the lens  24  produces an image of a rectangular shape, for example, on a CCD (or a CMOS) of the image pickup device  22 , the light flux  37  before entering into the lens  24  has a cross-sectional shape surrounded by light flux lines  41  such that the corner optical path portion  39  tends to protrude (the corner extends radially). Specifically, in a case of a lens  24  of a wide-angle lens system, the light hits obliquely on a peripheral portion of the CCD. When the light obliquely enters the CCD, electric charge cannot be generated sufficiently. The diagonal corner portion has a tendency to protrude in order to compensate for this of the light amount. 
         [0034]    Here, for example, as shown in  FIG. 6C , when using the light shielding member  105  of the circular shape according to the comparative example similar to the related art, as shown in  FIG. 7A , the corner optical path portion  39  protruding outward is positioned the outside of the light shielding member  105  and is vignetted. As a result, as shown in  FIG. 7B , the image becomes dark at the diagonal corner portion. 
         [0035]    In contrast, in the configuration using the light shielding member  30  according to the embodiment shown in  FIG. 6B , as shown in  FIG. 8A , the triangular bulging-shaped portion  36  outwardly protruding from the circular opening shape portion  40  is provided at a position corresponding to the corner optical path portion  39 . Accordingly, the optical path for the diagonal corner is secured, which is necessary at the time of wide angle of the lens. The lens optical path and an image pickup range generally tend to protrude in the diagonal corner portion. With this configuration, as shown in  FIG. 8B , the image with no vignetting can be obtained without increasing the diameter of the light shielding member  30  as a whole, by outwardly extending only the optical path portion  39  in the light shielding member  30 . 
         [0036]    Next, a modification of the light shielding member  30  is described. 
         [0037]    As shown in  FIG. 5B , the opening of the light shielding member  42  may have a shape similar to a cross sectional shape of the light flux  37  on a plane  43  (see  FIG. 6A ) orthogonal to a center axis of the light flux  37  which corresponds to the angle of view in the image pickup device  22  and which enters from the object into the lens  24 . 
         [0038]    According to the light shielding member  42  of the modification, the shape thereof is somewhat complicated. However, the light shielding member  42  can be formed in a minimum size without occurrence of the vignetting. 
         [0039]    As shown in  FIG. 5C , the opening of the light shielding member  44  may be a rectangular shape which is defined by straight lines which connect the protruding ends of the adjacent corner optical path portions  39 . 
         [0040]    According to the light shielding member  44  of the modification, the light shielding member  44  can be produced in the rectangular shape which is easily manufactured without the vignetting. Even in the case, the light shielding member  44  can be formed smaller than the case where the light shielding member  105  of the circular shape of the related art as a whole is increased in the diameter, since when the diameter of the light shielding member  105  is increased, the diameter of the opening becomes a diameter of a circumscribing circle of the rectangular shape of the light shielding member  44 . 
         [0041]    As shown in  FIG. 5D , the opening of the light shielding member  45  may have the half oval-shaped portion  38  which outwardly bulges from the circular opening shape portion  40  at the position corresponding to the optical path portion  39 . 
         [0042]    According to the light shielding member  45  of the modification, while the circular opening shape portion  40  of the light shielding member  30  is not changed from a shape of the related art, the half oval-shaped portion  38  protrudes radially from the circular opening shape portion  40 . Accordingly, it is not necessary to largely change the location of the infrared light source  26  from the related art. In addition, according to the configuration, the manufacture becomes easy. Furthermore, by changing the protrusion length of the half oval-shaped portion  38 , the light shielding member can easily deal with the optical path portion  39  where the degree of the protrusion increases and decreases according to the degree of the wide angle. 
         [0043]    According to the surveillance camera  11  of the embodiment, the product can be decreased in size while obtaining the wide angle image without vignetting. 
         [0044]    The embodiment may be applied to the camera apparatus corresponding to the wide angle image without enlarging the cross section of the product. 
         [0045]    This application claims the benefit of Japanese Patent Application No. 2011-170759 filed on Aug. 4, 2011, the contents of which are incorporated herein by reference.