Abstract:
A camera device with unitary interface cabling has a built-in balun for converting unbalanced video signal to balanced video signal for transmission from an on-board twisted pair video output connector, a power connector, a PZT control signal connector, and all said connectors adapted for linking with a category 5 of better network cable.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit under 35 USC §119(e) of the following patent application, the disclosure of which is hereby incorporated by reference thereto in its entirety: U.S. Ser. No. 60/568,678 filed May 7, 2004. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     This invention is related to the field of video cameras, more specifically to a camera with unitary interface cabling.  
       BACKGROUND OF THE INVENTION  
       [0003]     Digital video camera systems have many uses, in particular for surveillance or monitoring purposes. For example, such a camera system can be placed near an automatic teller machine (ATM), a cash register or a point of sales device (POS), or in the proximity of doorways of facilities such as office buildings or factories. Other applications include monitoring the entire duration of a process or operation.  
         [0004]     Any unauthorized acts or irregularity may be identified and followed up using the digital images captured with such a camera system.  
         [0005]     Although a number of existing cameras have on-board memory for the captured images, for long term monitoring or surveillance (hours if not days), a typical digital camera system is connected to a digital video recorder (DVR) or a video cassette recorder (VCR for analog signals) for large capacity storage of captured images. This connection is via a co-axial cable with BNC or TNC plugs. RG58, RG59 or RG6 co-axial cables have the disadvantage of requiring amplification for longer distances (over a few hundred feet) due to loss of high frequency signal drop.  
         [0006]     Sophisticated versions of such camera systems possess pan-tilt-zoom capability under digital electronic control. The image capturing and processing elements of such a system including the lens are mounted such to have the centre of the field of view mechanically pointed at different pan-tilt angles. The images may be optically or digitally zoomed.  
         [0007]     Although PTZ control can be done manually, as for example using switches or toggles on the camera system, typically, the camera system receives digital PTZ instructions via a telecommunication connection from a server on a network under the control of a human user. (The server may also issue PTZ instructions to move the camera either continuously or periodically to cover a larger surveyed or monitored field.)  
         [0008]     Power to the camera system is provided from a power outlet.  
         [0009]     As a result, a typical camera system requires 3 separate cables for: (1) video output, (2) PTZ control; and (3) power. Such a system would be cumbersome and costly to install and manage. For example, for a system with 16 camera systems in a surveillance network, a technician would have to use 48 cables, perhaps over several thousand feet of distance.  
       SUMMARY OF THE INVENTION  
       [0010]     The invention has the object of providing a camera system with a minimal number of interface cables.  
         [0011]     This invention provides a camera device with unitary interface cabling having a built-in balun for converting unbalanced video signal to balanced video signal for transmission from an on-board twisted pair video output connector, a power connector, a PZT control signal connector, and all said connectors adapted for linking with a category 5 network cable.  
         [0012]     Additionally, the video signal can be converted to a digital signal in the camera prior to transmission.  
         [0013]     This invention provides a camera device with greatly reduced wire requirements with acceptable loss ratios for ranges up to 1000 feet using category 5 network cable without additional amplification. The camera connection is much simpler, and the signal is easily reconverted using another balun at the receiving end of the category 5 network cable. The modification of existing video cameras to transmit power, video and control signals over standard network cabling creates a useful standard for digital surveillance video management systems. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a perspective view of a preferred embodiment of the invention with an interface cable.  
         [0015]      FIG. 2  is a rear view of the camera system of a preferred embodiment showing connectors for the unitary interface cable and optional controls and co-axial signal connector.  
         [0016]      FIG. 3  is a schematic of the internal connection between the camera and the cabling interface for connection to category 5 network cables. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     A detailed description of the embodiments of the invention will now be provided with specific reference to the drawing illustrating a preferred embodiment of the invention. Like structures will be provided with like reference numbers.  
         [0018]      FIG. 1  is a perspective rear view of a preferred embodiment of the invention showing a single interface cable  20  connected to a camera system  10  of the subject invention. The interface cable  20  is preferably a category 5 cable with 4 twisted pairs of wiring. Higher grade network cabling can also be used in the spirit of the immediate invention, with modifications to the connection interface, or by using adapters to convert the available wire connection to one compatible with category 5.  
         [0019]      FIG. 2  is a rear view of a preferred camera system  10  showing a possible set of switches and terminals on a rear panel  30 . The top part of the panel contains a number of optional elements. A TELE element  40  provides manual control for increased magnification of an image in the field of view (zooming into the image). A WIDE element  50  provides manual control for lower magnification (zooming out). These two elements  40   50  are preferably button-type controls.  
         [0020]     Backlight compensation (BLC) for improved image quality where there is a bright light source in the image background may be manually turned on or off by using the BLC switch  60 . A menu switch  70  serves to permit selecting from a menu (not shown). A co-axial video output connector  80  (a BNC connector) is included for transmitting video output signals down a co-axial cable. However, a user may manually elect between transmitting video output in this fashion or down a twisted-pair cable using a output selector  90 .  
         [0021]     The basic configuration of the preferred embodiments includes a number of elements then shown in  FIG. 2 . A balun (shown in  FIG. 3 ) converts unbalanced video output signal generated for transmission down a co-axial cable to a balanced signal for a twisted pair cable (typically using 24 AWG wires). The converted signal is sent through the twisted pair video output connector  100  (shown as a pair of terminals in  FIG. 2  but not limited to such). PTZ control signal is received by the camera system  10  through a PTZ signal connector  110  (shown as a pair of terminals in  FIG. 2  but not limited to such), corresponding to the Rx pins  
         [0022]     Balun technology has resulted in audio-video performance for twisted pair wired transmission that is comparable to coaxial cable wired systems and in some instances surpass co axial cable in terms of distance. This is due primarily to twisted pair&#39;s noise cancellation effect when the video is transmitted as a balanced signal.  
         [0023]     Power for the camera system  10  is received by a power input connector  120  (shown in  FIG. 2  as a pair of terminals). This is preferably of 24V AC/DC compatible type.  
         [0024]     Embodiments of this invention include or are capable to use a single interface cable  20  including at least 4 conductor (wire) pairs for sending PTZ control signal and electrical power to, and receiving video signal from, the camera system  10 . This interface cable  20  is preferably a category 5 network cable, with 4 pairs of wires (at least 22, preferably 24, AWG). One wire pair is attached to each of the twisted pair video output connector  100  and the PTZ signal connector  110 ; One pair is connected to the positive and the other pair to the negative terminals of the power input connector  120 .  
         [0025]     In preferred embodiments, there may be a pair of plug and receptacle (jack) that provides the link between the interface cable  20  and the camera system  10 . Such a plug may be of any suitable type such as RJ45, DB9, DB25, and etc. In this fashion, removal and installation of a camera system  10  is made easier and faster.  
         [0026]      FIG. 3  shows a schematic of how the network cable  20  comprising 4 twisted pairs  21 ,  22 ,  23 , and  24  may be connected through an optional standard category 5 network jack. Internally, the jack  130  is connected to PTZ signal connector  110  at jack connection pair  131  such that twisted pair  21  makes a connection with the PTZ controller. Internally, the jack  130  is connected to the balanced video output connector  100 , at jack connection pair  132  such that twisted pair  22  makes a connection with the video output connector  100 , which is itself connected internally to the co-axial video output connector  80  via an appropriated balanced balun  130 . The jack  130  is connected to the input power lines  120  of the camera at jack connection pairs  133  and  134 , such that twisted pair  23  and twisted pair  24  can make a power signal connection with the power input connector  120 . Where it is known in advance that a particular camera will always be connected in this fashion, these connections may all be made internally, and connectors  80 ,  100 ,  110  and  120  covered by a plate (not shown) featuring only the network cable jack  130 . A plate, bearing a jack, the tuned balun and wiring can be provided as a kit to convert existing cameras to this standard. The jack  130  is typically of any suitable type such as RJ45, DB9, DB25, with a corresponding plug (not shown) on the cable  20 . The RJ45 standard has 8 pins or 4 pairs of pins. Without loss of generality, we refer to the connections on the male and female plugs as pins. Typically, a technician would have the male plug on the cable and the female plug on the device, but it would be within the scope of this invention to make the obvious reversal.  
         [0027]     The interface cable  20  is connected on the other end to a source of electrical power, a source of PZT control signals, and a receiver for the video signal. The receiver preferably includes a converter for changing the balanced signal from the camera system  10  to an unbalanced signal for feeding to a DVR system (which may also incorporate the PZT control signal generator). As at the camera system  10  end, a pair of plug and receptacle may provide a easily disengageable link between the interface cable  20  and the sources of electrical power and PZT control instructions, and the video signal receiver.  
         [0028]     It will be appreciated that the above description relates to the preferred embodiments by way of example only. Many variations on the system for delivering the invention will be clear to those knowledgeable in the field, and such variations are within the scope of the invention as described and claimed, whether or not expressly described. In particular, it will be noted that the preferred embodiments of the invention only require twisted pair network cable comprising at least 4 pairs. While category 5 cabling is specifically mentioned, category 5 enhanced, category 6, category 7 (planned) and other shielded or unshielded cabling may be used. The key import being that the balun must be balanced to the cable to allow full range benefits.