Abstract:
A surveillance system includes a stationary camera module, a movable camera module, and a control unit. The stationary camera module fixedly surveils a total field of view of the surveillance system. The movable camera module movably surveils portions of the total field of view of the surveillance system. The control unit is connected with the stationary camera module and the movable camera module, controlling movement of the camera module.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to surveillance systems and, particularly, to a surveillance system with dual camera modules. 
         [0003]    2. Description of Related Art 
         [0004]    Many surveillance systems utilize cameras that are stationary, while others provide movement of the camera within a fixed field. Both systems present limitations. Stationary camera systems often are required to capture images with a wide angle, thus deteriorating video clarity. Movable camera systems, while widening the surveilled area, may miss some activities. 
         [0005]    Therefore, it is desirable to provide a surveillance system which can overcome the limitations described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a functional block diagram of a surveillance system, according to one embodiment. 
           [0007]      FIG. 2  is a cross-section of a movable camera module and a stationary camera module of the surveillance system of  FIG. 1 . 
           [0008]      FIG. 3  is an exploded, isometric view of the movable camera module of the surveillance system of  FIG.1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    Embodiments of the disclosure are now described in detail with reference to the drawings. 
         [0010]    Referring to the  FIGS. 1-2 , a surveillance system  100 , according to one exemplary embodiment, includes a stationary camera module  10 , a movable camera module  20 , a base plate  30 , a control unit  40 , a display unit  50 , and a receiving unit  60 . 
         [0011]    The stationary camera module  10  includes a fixed focus lens, and is configured for capturing information from a total field of view of the surveillance system  100  to form global images. In particular, the stationary camera module  10  includes a lens holder  11 , a first lens barrel  12 , and a first image sensor  13 . The first lens barrel  12  is partially received in the lens holder  11 . The first image sensor  13  is disposed under the first lens barrel  12 , received in the lens holder  11 , and configured for converting light passing through the first lens barrel  12  to electric image signals. To monitor a wider area, the stationary camera module  10  is a wide-angle camera module capable of capturing a field angle of about 110°. 
         [0012]    Referring to  FIG. 3 , the movable camera module  20  includes a zoom lens and is configured for capturing information from portions of the total field of view of the surveillance system  100  to form partial images. The movable camera module  20  moves during capture. The movable camera module  20  includes an outer frame  21 , four inductive coils  22 , an inner frame  23 , four magnetic elements  24 , four elastic elements  25 , a second image sensor  26 , and a second lens barrel  27 . To avoid distortion during video capture, the movable camera module  20  has a field angle less than about 60°. 
         [0013]    Also referring to  FIG. 3 , the outer frame  21  is a hollow cubic configuration, and includes a bottom plate  211  and four side plates  212 . The four side plates  212  perpendicularly connect to the edges of the bottom plate  211 , and form a first receiving room  213 . The bottom plate  211  defines a guide groove  211 a therein. The guide groove  211 a is a spherical cap. Each of the side plates  212  defines an elliptical receiving hole  214  therethrough. Each of the inductive coils  22  is an elliptical ring fittingly received in the receiving holes  214  respectively. 
         [0014]    The inner frame  23  includes a receiving frame  231  and a guide projection  232  depending from the bottom of the receiving frame  231 . The receiving frame  231  is hollow and cubical including four sidewalls  231   a  and an upper surface  231   b.  The receiving frame  231  defines a second receiving space  233  in the upper surface  231   b . The shape of the guide projection  232  is corresponded to that of the guide groove  211   a  and, cooperating with the guide projection  232 , forms a universal joint between the outer frame  21  and the inner frame  23 . 
         [0015]    Each of the magnetic elements  24  includes an upper magnet  241  and a lower magnet  242 . The magnetic elements  24  are disposed on the sidewall  231   a  of the receiving frame  231 . The upper magnet  241  is adjacent to the upper surface  231   b  and the lower magnet  242  is separated from the upper surface  231   b . In this embodiment, the S pole of the upper magnet  241  is adjacent to the sidewall  231   a  and the N pole of the upper magnet  241  faces away from the sidewall  231   a;  the N pole of the lower magnet  242  is adjacent to the sidewall  231   a  and the S pole of the lower magnet  242  faces away from the sidewall  231   a.    
         [0016]    The second image sensor  26  and the second lens barrel  27  are received in the second receiving room  233  in sequence. The second image sensor  26  is disposed under the second lens barrel  27 , and converts light passing through the second lens barrel  27  to electric image signals. 
         [0017]    In assembly, the inner frame  23  is received in the first receiving room  213  of the outer frame  21 . The guide projection  232  is correspondingly received in the guide groove  211   a . The magnetic elements  24  are opposite to the inductive coils  22  respectively. The elastic elements  25  are connected between the sidewalls  231   a  of the receiving frame  231  and the side plates  212  of the outer frame  21  respectively. The inductive coils  22 , when receiving different directions and amounts of current, generate different directions and amounts of magnetic fields correspondingly. The inner frame  23  is rotated on the guide groove  211   a.    
         [0018]    It is noteworthy to improve the quality of the surveillance system  100 , the number of pixels of the second image sensor  26  exceeds that of the first image sensor  13 . 
         [0019]    The base plate  30  is a print circuit board (PCB). The stationary camera module  10  and the movable camera module  20  are disposed on the base plate  30 , and electrically connected with the base plate  30 . 
         [0020]    The control unit  40  is connected with the stationary camera module  10  and the movable camera module  20  via the base plate  30 . The control unit  40  rotates the movable camera module  20 . 
         [0021]    The display unit  50  is connected with the control unit  40 , and configured for displaying the images captured by the stationary camera module  10  and the movable camera module  20  respectively. In this embodiment, the display unit  50  is a liquid crystal display (LCD). The display unit  50  is divided into a first display area and a second display area (not shown). The first display area and the second display area display the images captured by the stationary camera module  10  and the movable camera module  20 , respectively. 
         [0022]    The receiving unit  60  is connected with the control unit  40 , and configured for receiving operating commands. In this embodiment, the receiving unit  60  can be a touch-panel or a keypad. 
         [0023]    In operating, the stationary camera module  10  captures consecutive global images of the total field of view of the surveillance system  100 , and the global images are displayed on the first display area. The movable camera module  20  is driven by the control unit  40  to capture consecutive partial images in a patrol fashion, such as by panning clockwise at a preset speed. The partial images are displayed on the second display area. Since the movable camera module  20  has limited the field angle capability and increased number of pixels thereof, the partial images can capture details of the surveillance in the patrol fashion. When activity of note is shown in a portion of the total field of view of the stationary camera module  10 , the movable camera module  20  can be panned to the specific area via the control unit  40  for details. 
         [0024]    It is noteworthy that, for convenience of operation of the surveillance system  100 , the control unit  40  can be configured so that the movable camera module  20  can relocate to a position dictated by operating input. 
         [0025]    It will be understood that particular embodiments and methods are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.