Abstract:
A surveillance camera system capable of accepting any appropriate surveillance camera and video transmission option and is programmed to operate with a multitude of competitive communication protocols with minimal servicing required. The system can quickly convert and/or update the camera system to be able to transmit video data over coaxial cable, unshielded twisted-pair (UTP), fiber optics or IP. A conversion from UTP to IP can convert the camera assembly into a network server for TCP/IP communication enabling the camera to be controlled locally or from any location over the internet using any installed network video protocol. The camera assembly with the ability to quickly configure the communication video interface via switch selectable on-board communication protocols.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a surveillance camera system and, more particularly, to surveillance cameras for use with closed-circuit television systems, such as for indoor or outdoor store security, building security, and any other security or monitoring applications.  
       BACKGROUND OF THE INVENTION  
       [0002]     Surveillance camera systems are commonly used to monitor various areas, such as cashier windows, store parking lots or gambling tables at a casino. Typically, an operator of such a surveillance system is located at a central location from which he controls one or more camera units that are remotely positioned throughout the area to be monitored. The remote units are often mounted in hemispherical domes that are suspended from the ceiling of the monitored area. By using a keyboard console, the operator selects images from the remote cameras to be displayed on one or more video monitors. Some systems include a joy stick on the control console to permit the operator to reposition a camera in order to obtain a better view of a particular zone of observation. Prior art surveillance cameras also have operated in operator selectable automatic pan modes in order to provide full, continuous coverage of areas of surveillance. Generally, such cameras have been of the continuous scan type which pan or oscillate through an arc continuously at a fixed speed until stopped by an operator.  
         [0003]     A disadvantage of the known surveillance camera systems relates to the difficulty of installing, updating and servicing the systems. More specifically, the prior art surveillance camera systems have been complex electromechanical structures and when servicing was required, it would usually require removal and reconfiguration of the entire structure which was not always an easy, time-effective procedure. Furthermore, a building in or about which the remote camera units are deployed may have varying data transmission systems in place for transmitting video data. For example, the buildings may be pre-wired for video for transmitting video data. For example, the buildings may be pre-wired for video transmission over fiber-optics, coaxial cable, twisted-pair or TCP/IP (several of which also have the ability to work with various competitive protocols). Prior surveillance camera systems leave something to be desired in accommodating such variations in data transmission and protocols associated with each transmission system. Further still, in many cases, whereas known surveillance camera systems provide for competitors protocols integral in their respective domes, this capability has been provided through the use of module upgrades. Because such protocols are usually contained in the main control board above the camera, upgrading video protocols commonly requires disconnecting the camera and drive motors from the system and replacing the main control board.  
         [0004]     It would be desirable to provide such a camera in a aesthetically pleasing, compact dome type housing, with the camera and its associated electronics being readily accessible and easily removable as a unit from its housing for upgrading connections and associated communication protocols.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention overcomes the disadvantages of the prior art by providing a surveillance camera system which is easy to install, upgrade and maintain, will accept any appropriate surveillance camera and video transmission option and is programmed to operate with a multitude of competitive communication protocols with minimal servicing required.  
         [0006]     The system is particularly advantageous in its ability to quickly convert and/or update the camera system to be able to transmit video data over coaxial cable, unshielded twisted-pair (UTP), fiber optics or IP. A conversion from UTP to IP can convert the camera assembly into a network server for TCP/IP communication enabling the camera to be controlled locally or from any location over the internet using any installed network video protocol.  
         [0007]     Another significant aspect and feature of the present invention is a camera assembly with the ability to quickly configure the communication/video interface via switch selectable on-board communication protocols.  
         [0008]     According to another aspect and feature, a single video communication board included in the surveillance camera system can be configured to support a plurality of communications/video interfaces. Alternatively, a video communication board configured for operation with a single video interface can be easily removed and replaced for a communication board with a different communications/video option. The video interface board is pivotally mounted to allow easy access and quick configuration of multiple communication/video interfaces. In a locked position the interface board rests securely against the top wall of the camera housing, while in an unlocked position the interface board can be pivoted to a vertical position where it is exposed to the user for connection with an appropriate video interface.  
         [0009]     These and further aspects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is an exploded perspective view of the major components of an indoor television camera system enclosed in a dome shaped case of the present invention;  
         [0011]      FIG. 2  is a top perspective view of a ceiling mount for use with the system in  FIG. 1 ;  
         [0012]      FIG. 3A  shows in detail a partial cross sectional view of the housing of an indoor camera system of  FIG. 1 ;  
         [0013]      FIG. 3B  shows in detail a front elevation view of the housing of an indoor camera system of  FIG. 1 ;  
         [0014]      FIG. 4A  shows in detail a bottom plan view of the housing of an indoor camera system of  FIG. 1 ;  
         [0015]      FIG. 4B  shows in detail a top plan view of the housing of an indoor camera system of  FIG. 1 ;  
         [0016]      FIG. 5A  is a top plan view of a segment of the camera system that includes the camera drive apparatus;  
         [0017]      FIG. 5B  is a front elevation view of a segment of the camera system that includes the camera and camera drive apparatus;  
         [0018]      FIG. 5C  is a left side elevation view of a segment of the camera system that includes the camera and camera drive apparatus;  
         [0019]      FIGS. 6A-6B  are top front perspective and front elevation views, respectively, of a video interface board according to a first embodiment of the invention;  
         [0020]      FIGS. 7A-7B  are top front perspective and front elevation views, respectively, of a video interface board according to a second embodiment of the invention;  
         [0021]      FIGS. 8A-8B  are top front perspective and front elevation views, respectively, of the video interface board of  FIG. 7A  incorporating a fiber optics module;  
         [0022]      FIGS. 9A-9B  are top front perspective and front elevation views, respectively, of a video interface board according to a third embodiment of the invention;  
         [0023]      FIGS. 10A-10B  are top front perspective and front elevation views, respectively, of a video interface board according to a forth embodiment of the invention;  
         [0024]      FIG. 11  is a front perspective view showing the details of a camera positioning mechanism according to a preferred embodiment of the invention;  
         [0025]      FIGS. 12A-12B  are top left perspective and rear right perspective views, respectively, of an optional heater module incorporated in a camera system of the present invention;  
         [0026]      FIG. 12C  is a cross sectional view of an optional heater module incorporated in a camera system of the present invention;  
         [0027]      FIG. 13  is a cross sectional view of the heater module of  FIG. 12C  taken essentially along the line  13 - 13 ;  
         [0028]      FIGS. 14A-14C  are top plan, front elevation, and bottom plan views, respectively, of a pan or tilt motor according to the preferred embodiment;  
         [0029]      FIG. 15  is an exploded elevation view of the major components of an indoor television camera system enclosed in a dome shaped case of the present invention;  
         [0030]      FIG. 16  is an exploded elevation view of the major components of an outdoor television camera system enclosed in an outdoor cover;  
         [0031]      FIG. 17  is a top right perspective view showing camera orientation within the camera system;  
         [0032]      FIG. 18  is a top front perspective view of an outdoor cover of  FIG. 16 .  
         [0033]      FIG. 19  is a partial cross sectional view of the outdoor cover of  FIG. 18 ;  
         [0034]      FIG. 19A  is an enlarged cross sectional view showing the circled portion of  FIG. 19 ;  
         [0035]      FIGS. 20-21  illustrate in diagrammatic views the manner in which a privacy mask is established on an on screen display for a surveillance camera system according the present invention; and  
         [0036]      FIG. 22  illustrates in diagrammatic view a menu interface for controlling the operation and configuration of the privacy masks shown in  FIGS. 20-21 .  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0037]     Referring to  FIG. 1 , a surveillance camera system  104  according to the present invention comprises housing  100 , camera drive  105 , video camera  110 , shroud  115  and dome  120 . Housing  100  encloses the components of the surveillance camera system  104  above the ceiling. Preferably, surveillance camera system  104  is installed into an orifice  101  of an existing ceiling  102  in the area to be monitored and rests on the inner ceiling surface occupying the space between ceiling  102  and the upper building frame (not shown). During installation, housing  100  is lifted up through orifice  101  and a pair of locking flippers  125  are secured against ceiling  102  thereby securing housing  100  to ceiling  102 . If necessary, additional support for housing  100 , other than the ceiling  102  material, can be provided through the use of optional support rails  205 , as shown in  FIG. 2 . Support rails  205  can be formed at one end to be attached to housing  100  and at the other end to be attached onto an inner surface of ceiling  102 , essentially acting to distribute some of the weight of camera system  104  along the length of rails  205  and the contacted ceiling portion. An additional mounting ring  122  may be provided between rails  205  and housing  100  for further support and distribution of the weight assembly  104  or to assist in connecting rails  205  to housing  100 . Dome  120  is a hemispherical, translucent dome preferably formed of an acrylic material and extends below ceiling  102  enclosing camera  110  and shroud  115 .  
         [0038]     By way of overview, camera  110  of surveillance camera system  104  captures real-time images of a selected area and transmits the images to a remote operating consol, or possibly to multiple monitoring stations, for viewing by an operator. A number of surveillance camera systems  104  may be located at strategic locations throughout the monitored area to provide multiple views of the area to the remote operating consol. Synchronization of sync signals from several remotely spaced cameras providing a remote operator the ability to split a screen display between the output of several cameras is discussed in U.S. Pat. No. 4,860,101, entitled Central Station Synchronization System.  
         [0039]     Referring to  FIG. 1 , surveillance camera system  104  includes a customer interface board  130  (shown best in  FIGS. 15 and 16 ) pivotally mounted in the top of housing  100 , that can be pivoted and removed if desired for easy access to video connectors. As described in further detail below, wiring is provided to the customer interface board  130  through orifice  101  for propagating power, video, control and other signals to camera  110 . Optional wiring can be installed for use in relay output and alarm inputs. Additional wiring connecting camera  110  to an appropriate video interface can be accomplished through connection with customer interface board  130 . Cables  131  for all wirings to customer interface board  130  are routed from above ceiling  102  through conduit  180  of housing  100 .  
         [0040]     Referring to  FIG. 5A-5C , directly below customer interface board  130  rests camera drive  105 .  FIG. 11  shows camera drive  105  separate from shroud  115  with portions of its outer casing removed for clarity. Camera drive  105  is operable to orientate the camera in 360° azimuth (pan angle) and 180° elevation (tilt angle) and comprises a removably mounted camera  110 , pan-and-tilt drives  370 ,  136  and CPU  206 . The panning motor  370  rotates camera  110  about the horizontal axis causing a well-known panning movement of the camera  110 , while the tilting motor  136  rotates camera  110  about the vertical axis causing a well-known tilting movement. Camera drive  105  can be removably secured in housing  100  through the use of any available connection means known by those of skill in the art, such as by screws, guide rails, clips, cords, etc. According to a preferred embodiment camera drive  105  is configured for snap-in installation into housing  100 .  
         [0041]     As illustrated in  FIG. 1 , dome  120  is releasably fastened to housing  100  by a set of four interlocking tabs  121  that may be positioned onto mating supports about the lower rim  122  of housing  100 . Interiorly of dome  120  is a further dome-like member or shroud  115  which rotates with camera  110 . Shroud  115  is opaque and provides camouflage for camera drive  105  and camera  110 , except for a defined viewing region which is aligned with viewing direction  116 . The viewing region is in the form of a slot  117   a  in the shroud which runs from the apex  117   b  of the shroud vertically circumferentially through an angle of approximately ninety degrees, as is seen in  FIG. 17 . This permits the viewing direction  116  to be pivoted or tilted from a horizontal position to a vertical position (directed downwardly) for each pan position of surveillance camera  110 . Shroud  115  is releasably fastened to camera drive  105 , preferably configured for snap-in connection, and as discussed can be textured such as to conceal the position of camera  110 .  
         [0042]     According to a salient aspect of the present invention, a safety chain or cord  145  including a clip  147  may be provided to keep camera drive  105  loosely attached to housing  100  for servicing, installation or adjustment of the unit. Safety cord  145  can support the weight of camera drive  105  and is useful in preventing mishaps which can occur while installing the camera system, such as accidentally dropping camera drive  105 . For similar reasons, another safety cord  146  and clip  148  connect dome  120  to housing  100 .  
         [0043]     As briefly discussed above, and discussed below in further detail, the surveillance camera system  104  includes a video camera  110  such as model No. VK-S454R camera sold by Hitachi. The video camera is a compact chassis type camera which is designed for surveillance under a wide range of light conditions. Camera  110  includes a lens assembly  131  having controllable lens zoom, focus and iris functions. Camera  110  includes a video sensor (not shown) mounted to the rear of the lens assembly  131  at its focal plane and a camera electronics package for converting sensed images to video signals. Referring to  FIG. 17 , the lens assembly  131  has an optical axis  116  and camera  110  is removably mounted upon camera drive  105  with its optical axis  116  intersecting the pan axis and transversing tilt axis. In this way, the camera optical axis  116  remains normal to the surface of the dome  120  in all possible pan and tilt orientations of the camera. Further, the center of gravity of the camera  110  and lens assembly  131  is preferably close to the intersection of the vertical pan and horizontal tilt axis such that the camera and lens assembly is kinematically balanced for rapid pan and tilt movement rates. With the camera&#39;s center of gravity located closely adjacent the intersection of the pan and tilt axes, high speed camera movements can be made and the camera brought to rather abrupt halts quite smoothly with unperceivable wobbling actions developed by camera  110  and camera drive  105  momentum. These axes are also located so as to intersect at or close to the center of the spherical housing when the camera and camera drive are secured therein. Accordingly, the housing diameter required to accommodate the full range of movement of the camera and drive is minimized such that the smallest possible dome  120  can be used. Further, with this configuration, the camera&#39;s optical axis  116  is always oriented substantially normal to the surface of the dome  120  regardless of the camera&#39;s orientation with respect to the pan and tilt axes. This serves to minimize some generated image refractions which tend to impede optical quality of the image transmitted to the camera.  
         [0044]     A preferred mechanism for rotating camera  110  in 360° pan and 180° tilt, sensing the exact direction in which the camera is pointed and enabling rapid recalibration of the camera unit is provided in U.S. patent application Ser. No. 10/312,457, filed Jun. 22, 2001 entitled Dome Housed Video Camera Assembly with 180 Degree Tilt Motion, the entirety of which is hereby incorporated by reference and therefore, not described in full detail. Additionally, video camera  110  is conventionally provided with power terminals for connecting the camera with electrical power and with video input and output terminals for receiving and outputting video and control signals from and to a local CPU and a remote computer.  
         [0045]     Referring to  FIG. 6A-6B , customer interface board  130  comprises inputs for power T 1 , alarms T 2 , relay/control signals T 8  and video signals via coaxial cable input T 4 , UTP input T 3  or fiber optic input T 6 . Alarm input signals  215  and relay output signals  220  are carried on individually-shielded twisted pair cable sets. Relay output signals drive external devices, e.g., a light can be turned on and off when the relay output is connected to the light circuit. Alarms are electronic CMOS level type inputs that are driven by a contact type switch with two states, open and closed. For example, a switch connected a door of a building can trigger an alarm when connected to the alarm input T 2  and the door is opened.  
         [0046]     According to a preferred embodiment of the present invention, surveillance camera system  104  can be configured to accommodate alternative video configuration interfaces, i.e., coaxial cable, fiber optic, twisted-pair, IP. As shown, this can be accomplished by a single customer interface board  130  comprising multiple video interface options to accommodate the available video transmission medium present at the installation site or by multiple interchangeable customer interface boards  130  each configured for a different video configuration (see  FIGS. 7-10 ).  FIGS. 4A-4B , illustrates an inner and outer view of the top wall of housing  100 . Housing  100  includes hinge apparatus  400  and board retention means  403  for supporting customer interface board  130 . As shown, customer interface board  130  is pivotally attached inside housing  100  by hinge  400 . Hinge  400  includes pivotal connection points  401 A,  401 B enabling rotation of customer interface board  130  about the hinge-axis H. Board retention means  403  is preferably a tab configured to releasably secure customer interface board  130  proximate the top inner wall of housing  100 . In the event that replacement of customer interface board  130  is required during installation or updating of surveillance camera system  104  (e.g., changing the video interface option), the camera drive  105  can be detached from housing  100  and left to rest on safety cord  145  while the customer interface board  130  is unlatched from tab  403  and rotated 90° downward to the vertical position. From the vertical position customer interface board  130  can be disconnected from hinge  400 , removed from housing  100  and an alternative customer interface board  130  with the appropriately desired video interface option can be installed after which camera drive  105  can be reinserted in housing  100 . Alternatively, according to the embodiment of  FIGS. 6A-6B , a single customer interface board  130  can be configured to include a plurality of video interface options via connectors T 3 , T 4 , T 6  and T 5  ( FIGS. 9A-9B ). In this manner, changes in video transmission can be accomplished through accessing a single board by rotating the board to the vertical position and making all necessary connections to the terminal block used for implementing the desired transmission medium.  
         [0047]     Once connected to power, alarms, relay and video terminal, the surveillance camera system&#39;s  104  video protocols can be configured according to the appropriate video interface employed by setting on-board switch selectable video protocols on camera control board  206  ( FIGS. 5A-5B ) of camera drive  105 . Referring to  FIGS. 5A-5B , switches  202  enable configuration of camera control board  206  for a particular communications protocol locally and various alternative communication protocols can be realized by setting the switches accordingly. According to one aspect of the present invention, switches  202  are a plurality of DIP switches having two possible positions: on or off. It should also be realized that according to other aspects of the invention, control board  206  can be configured remotely via a user interface for updating software versions and setting the units address by entering software commands at the remote operating consol as opposed to setting onboard switches.  
         [0048]     After all terminal connections with customer interface board  130  have been made and switches  202  on camera control board  206  has been set to configure the on-board video protocols, camera drive  105  can be mounted in housing  100 . Camera drive  105  is aligned with housing  100  and guided upward into housing  100  until it snaps into place with connector  298  on camera control board  206  fitting securely with a mating connector on the control interface board (not shown). All communication between camera drive  105  and customer interface board  130  is achieved through control board  206 , connection with which is made available by connector  298 . Any alignment means conventionally known in the art may be provided for aligning and retaining camera drive  105  with housing  100 . For example, camera drive  105  may contain guide grooves on its outer perimeter that mate with ribs on housing  100 , or vis-versa. Lastly, dome  120  is attached to housing  100  to complete the installation of surveillance camera system  104 . Tabs  121  of dome  120  are lined up with corresponding recesses (not shown) on lower rim  122  of housing  100  and dome  120  is locked into place with the upper edge of the dome  120  flush with ceiling  102 .  
         [0049]      FIGS. 7-10  show four variations of customer interface board  130  configurations provided to support a different combination of video connections (i.e., coaxial cable, fiber optics, twisted pair, and IP/TCP) in accordance with the present invention. As such, one customer interface board  130 A can service more than one video transmission option and need not be replaced every time a system change is required. Referring to  FIGS. 6A-6B , coaxial cables carry the composite video signal and control signals out of surveillance camera system  104  through connector T 4 . According to an alternative arrangement, as opposed to utilizing coaxial cable, customer interface board  130 A can also be connected to transmit video over twisted-pair wires connected to terminal T 3 . Alternatively, if transmission of video data using fiber optic cable is desired, a fiber optic interface module  610  with a standard fiber-optic connector T 6  can be connected for communication with customer interface board  130 A through connector  609 . In this instance, video data is carried through connector  609  on customer interface board  130 A to fiber optic interface board  610  and output via a standard fiber optic connect T 6 . Further still, if network access is desired, a LAN interface module  510  ( FIGS. 9A-9B ) can be connected for communication with customer interface board  130 A through connector  508 . Accordingly, video data is carried through connector  508  to LAN interface module  510  and output via terminal T 5  of the LAN module. LAN interface board  510  enables customer interface board  130 A to transmit video data over TCP/IP and can be controlled locally or remotely, from any location over the internet using a pre-installed network video protocol.  
         [0050]      FIGS. 7-10  illustrate an arrangement for four customer interface board configurations embodied by the customer interface boards  130 B,  130 C and  130 D according to a preferred embodiment of the present invention. Referring to  FIGS. 7A, 7B ,  8 A and  8 B customer interface board  130 B is configured to transmit video data over coaxial cable connected to terminal T 4  or fiber optic by the addition of fiber optic interface board  610 . If fiber optic transmission is desired, fiber optic interface module  610  can be connected to the customer interface board via connector  609  and terminal T 6  on the interface board will support a fiber optic connection. Inputs for power T 1 , alarms T 2 , relay/control signals T 8  will remain connected to their respective terminals during the change from coax to fiber optic.  
         [0051]     Referring to  FIGS. 9A-9B , customer interface board  130 C is configured to support a network interface via a LAN interface module  510 . Video data is carried from customer interface board  130 C to LAN interface module  510  through connector  508  and output via terminal T 5  of the LAN module. LAN interface board  510  enables customer interface board  130 C to transmit video data over TCP/IP and can be controlled locally or remotely, from any location over the internet using a pre-installed network video protocol.  
         [0052]     Referring to  FIGS. 10A-10B , customer interface board  130 C is configured to transmit video data over coaxial cable connected to terminal T 4  or twisted-pair connected to terminal T 3 . If transmission over twisted-pair is desired, customer interface board  130 D, like  130   a - c,  can be pivoted on hinge  400  to the vertical position, twisted pair wires can be properly connected to terminal T 3  and board  130  can be locked back into place against the top wall of housing  100 . Prior to refitting camera drive  105  in housing  100 , the user may be required to set the appropriate switches  202  on the main CPU  206  to configure the video protocol for the UTP transmission. As discussed above with respect to the fiber optic board, all inputs for power T 1 , alarms T 2 , relay/control signals T 8  will remain connected to their respective terminals during the change from coax to UTP.  
         [0053]     In the preferred embodiment of the invention, video data streams are communicated to a computer from several remotely located surveillance camera systems. Ideally, video data streams are transmitted over coaxial cable using customer interface board  130   a  or  130   b.  Although a coaxial cable is preferred, the presently existing communications network in the building where the surveillance system is to be installed may support only a fiber optics network or perhaps both fiber optics and coax transmission mediums. Consequently, the surveillance camera system  104  can transmit video data streams over twisted pair wires, coaxial cable or a fiber optics network by accessing the customer interface board, connecting the desired transmission line to the appropriate communications terminal and setting the video protocol on the control board by accessing switches  202 . The specific communications protocol employed over the twisted pair, whether POTS, ISDN or ADSL, is not essential because all protocols can be preinstalled on the main board and programmably selected. The details of these protocols are generally known to those skilled in the art and no further discussion is therefore needed or provided herein.  
         [0054]     Because the baud rates of remotely located surveillance camera units may not necessarily be known at the time of installation, and indeed can be expected to vary from unit to unit, it has traditionally been necessary to have the installer of a unit perform on-site adjustment of control switch settings. Moreover, where a remotely accessible camera unit contains multiple serial ports, the overall hardware complexity and possibility for error in baud rate and line polarity adjustment for each serial port is substantially increased.  
         [0055]     Automatic baud rate detection allows a central monitoring station or remote computer to accept data from a variety of surveillance camera units operating at different speeds without establishing data rates in advance. This allows a surveillance camera to detect a new baud rate from the host computer without having to cycle AC power and is useful when the camera is set up remotely at one baud rate and the host computer configured at a different baud rate. The baud detector determines the speed and logic level of the incoming data stream by examining a character or multi-character string, which is usually a predefined 8-bit command character comprising the camera address and header identifier.  
         [0056]     The command may be transmitted with a leading start bit and a trailing, optional parity bit and one or two stop bits. The sequence of bit transmission begins with the start bit, which is followed by the command from the least significant bit (lsb) to the most significant bit (msb), the optional parity bit and then the one or two stop bits. Preferably, all commands are 8 bit characters with a leading start bit, a trailing stop bit and no parity bits. Since most communications lines are tied to a logic high level when data is not being transmitted over the line, the start bit is typically a logic “0”.  
         [0057]     Automatic baud rate detection is performed by a software routine executed by a host processor that is associated with the central monitoring station. If the software routine has not previously detected the baud rate, the software routine waits for the user to enter a command for a particular surveillance camera and then transmits it onto the output line. The software routine waits for the echoed command to return on the serial input line and then counts how long it takes for the bits of the command, including the start bit and the stop bits, to arrive on the input line. The software routine then calculates the baud rate that is required for transmitting the data to the remote device, stores the baud rate and initializes various transmit function registers in the serial communications controller to transmit at the required baud rate. Additionally, when a valid command is received by a surveillance camera with a valid address the baud rate and polarity is saved in non-volatile memory.  
         [0058]     In one example, the software routine counts how long it takes for the command characters to arrive by reading the input data stream and waiting for it to transition to a logic low level, which is assumed to be the start bit. A timer is started when the data stream transitions to a logic high level again with the lsb of the command. The software routine waits for the remaining bit transitions in the command and stops the timer at the beginning of the first stop bit. The timer value indicates how many clock cycles passed while the software routine waited for the eight data bits plus any optional parity bit.  
         [0059]     The advantage of using the camera address and header identifier information for baud rate detection is that if the remote computer is sending commands at various baud rates to several surveillance camera units, each individual camera will only look for commands to its own address and will not lock onto the wrong baud rate. Alternatively, a single byte, i.e., the character “A”, may be used to determine the baud rate as opposed to the 8-bit address and identifier information mentioned above. According to such an alternative arrangement, a surveillance camera can send out an the auto-baud character “A” upon power up or when prompted with a command from the remote computer.  
         [0060]     The baud rate on the remote computer is setup via manual programming, e.g., a user at a remote monitoring station programs the baud rate into a keypad by using a sequence of function keys and navigating through a menu system displayed on a local LCD display. An advantage of implementing the above described auto-baud detection feature is that if upon installation of a surveillance camera in a remote location a dip switch setting used to configure the video transmission protocol was mistakenly set to the wrong baud rate this error can be detected and the dip switch setting corrected accordingly. Additionally, polarity control is provided whereby a message will be displayed at the host computer indicating the transmit polarity, e.g., + or −, along with a request to send a command. Thereafter, the transmit polarity can be reversed by issuing an appropriate command from the host commuter. If a framing error is detected, the transmit polarity will revert back to the previous setting.  
         [0061]     Referring to  FIGS. 15 and 16 , surveillance camera systems  860  and  865  comprise camera  110 , mounting pipe  406  and housings  800 ,  820  and look like well-known pendant-mounted domed television cameras. Housings  800 ,  820  comprise a shell having a shape of a bell or of an acorn cup and a open base  805  to which the doom  120  is attached. Dome  120  is releasably fastened to base  805  of housings  800  and  820  by means of a set of four interlocking tabs  121  that may be rotary positioned onto mating supports about the rim of base  805 . Surveillance camera system  860  is preferably configured for use indoors and housing  800  is preferably composed of injection molded plastic. Surveillance camera system  865  is preferably configured for use outdoors in which case housing  820  is composed of diecast aluminum so as to provide added strength and protection to the enclosed camera drive.  
         [0062]     Housing  800 ,  820  comprises threaded upper opening  810  at the center of its top end for connection with mounting pipe  406 . Different shapes of pipe  406  are known. For example, pipe  406  can be straight for pendant mounting the surveillance camera system under horizontal structures or it can be formed or bent into L-shape or U-shape for mounting the surveillance camera system on vertical structures such as walls. Upper opening  810  is threaded into mounting pipe  406  using a well-known plumber&#39;s sealant tape or pipe lubricant/sealant to ensure that water will not leak into the surveillance camera system  860 ,  865 . It becomes clear that the surveillance camera systems  860 ,  865  having a shape of an acorn and comprising the camera  110  mounted onto the base  805  of housing  800  can be mounted outdoors exposed to rain or snow and that water will not leak into the camera, the pipe or the upper opening assembly.  
         [0063]      FIG. 16  shows an outdoor surveillance camera system  865  particularly equipped for extreme temperature and weather conditions. While similar to the arrangement of  FIG. 15 , surveillance camera system  865  further comprises an outdoor cover  900 . Outdoor cover  900  is attached to housing  820  and is effective to deflect heat energy, dissipate heat energy not reflected, and enable a high level of heat dissipation even when the camera is operated in sunlight at high ambient temperature. Outdoor cover  900  surrounds housing  820  completely, provides protection from radiant heat energy for the housing  820  and the surface itself is specified so that the emissivity is such that it reflects or deflects most of the radiant heat energy from the sun or any other hot body.  
         [0064]     Cover  900  performs multiple functions including providing additional protection for camera housing  820  and enclosed camera drive  105  by reflecting and removing radiant heat energy. Cover  900  also provides the means of preventing water from adhering to the dome  120  by providing a drip edge  908 . Cover  900  has vents  922  in a top portion that allow hot air to escape. Water that penetrates vents  922  is directed along its inner surface and exits the cover  900  at the open drip edge  908 . Additionally, cover  900  may further include water channels on its inner surface (not shown) for directing water from vent slots  922  outward from cover  900 .  
         [0065]     Outdoor cover  900  preferably functions as a sunshield for minimizing radiation heating of surveillance camera system  865 . Unlike conventional pendant mounted dome television camera&#39;s the present invention provides vent slots through the ceiling of outdoor cover  900  and a passageway exiting through the bottom of the cover to minimize heat build up in the air gap between the housing  820  and the cover  900 . As illustrated in  FIG. 18 , this sets up natural convention air paths and has the added benefit of providing additional cooling to housing  800  and its internal components. Dissipation of thermal energy through cover  900  is achieved by air moving through the air passage formed between the housing  820  and the cover  900  and upward through vents  922 . Under ordinary circumstances, convection will result in an upwardly moving air flow pattern which assists in dissipating thermal energy through the vents.  
         [0066]     Referring to  FIGS. 5A-5C  and  16 , camera drive  105  has the ability to accept a fan heater  648  for low temperature applications, without the use of additional hardware for installation. Heater  648  enables safe and efficient use of a video surveillance camera in an outdoor location over a wide range of ambient temperature and weather conditions. Preferably, heater  648  is configured for a snap-in fit with camera drive  105 . Shown independently in  FIGS. 12A-12C  and  13 , heater  648  has a compact form, and is configured to occupy not more than one-half, and preferably not more than one-sixth of the circumference of the housing  820 . Resistor heater elements  655  are disposed in fan heater  648  and mechanically fastened to mounting bracket  663 . The placement of the heating elements  655  in the assembly  648  assures that the air flow  65  will flow over both sides of heating element  655 , assuring maximum efficiency in heating the air, when heating is required. Fan heater  648  includes an inline thermal fuse  687  for providing over-temperature protection for resistive heating elements  655 . Fuse  687  responds to temperature by interrupting the electrical circuit when the operating temperature of heating elements  655  exceed the thermal rating of the fuse.  
         [0067]     According to a preferred embodiment, heater  648  is configured for snap-fit attachment with camera drive  105  via side flanges  659  such that it can be conveniently connected and disconnected as necessary. Side flanges  659  can be supplemented by retaining clips  657  ( FIGS. 5A-5C ) on camera drive  105  which can be bent against the side walls of heater  648  and secured into position between flanges  659 . Alternatively, heater  648  can be secured to camera drive  105  with the use of screws or other appropriate fastening means allowing its removable attachment to the camera drive. When this assembly is connected to camera drive  105  as shown in  FIG. 16 , operation of fan  662  provides air flow between camera drive  105 , housing  820  and dome  120 . The air flow pattern provides substantially even distribution of heat within the sealed chamber formed between housing  820  camera drive  105  and shroud  115 . Thermal energy in the circulating air flow engages the walls of housing  820  and dome  120 , enabling thermal energy to be conducted therethrough and dissipated from the surveillance camera system  865  through the wall of housing  820 . According to a salient aspect of the present invention, dissipation of heat generated by heater  648  is achieved through the air moving between the housing  800  and the cover  900  and upward through vents  922 .  
         [0068]     In cold ambient conditions, operation of the heater  648  can prevent formation of ice and frost on the dome  120 , which would interfere with operation of the video camera  110 . Fan heater  648  is preferably automatically controlled by a thermostat, preferably a solid state control, which can be connected to control board  206  and mounted in camera drive  105  or housing  820  and which can enable the video camera to operate properly over a temperature range of approximately −40° C. to approximately +55° C. The control circuit can be responsive to temperature inside the enclosure and can also be responsive to temperature outside the enclosure, for example responsive to solid state temperature sensors. Such solid state controls and sensors are known in the art, and are omitted for purposes of clarity.  
         [0069]     Referring to  FIG. 5A-5C , fan  372  is operable to circulate the heated air output by heater  648  when the heater is turned on or to circulate cool air about camera drive  105  when the camera drive is under warmer conditions. The speed of the fan is set as a function of the temperature of control board  206  temperature using a sensor or sensors (not shown) connected to board  206 . The maximum temperature read from a sensor is written to flash memory only when the camera&#39;s pan, tilt and zoom functions are inactive so that interrupts do not have to be disabled when writing to flash.  
         [0070]     Camera drive  105  comprises a pan and tilt assembly, generally designated as  55  ( FIG. 11 ) and a dome controller which is embodied in control board  206  of  FIGS. 5A-5C . Referring to  FIG. 11 , the pan and tilt assembly  55  includes a pan motor  370 , which is preferably a step motor, isolated from a pan motor platform  377  via rubber ring bumpers or spacers  375 . Spacers  375  are disposed between the pan motor  370  and the pan motor platform  377  to provide vibration isolation between the motor and platform. Spacers  25  also provide vibration isolation between motor  370  and housing  100 . Pan and tilt assembly  55  is fixedly attached within camera drive  105  by securing platforms  377  and  477  of the respective pan and tilt motors,  370  and  136 , to the camera drive apparatus. As shown in  FIGS. 14A-14C , platform  377  is includes tabs  385  operable to secure the pan motor assembly with camera drive  105 .  
         [0071]     Pan motor  370  includes a shaft  303  that passes through the pan motor platform  377  and extends to the underside of the platform. A gear  379  is affixed to the pan-motor shaft. A timing belt  56 , shown in phantom, mechanically couples gear  379  to drive a second gear  40  which is rotatably mounted to a portion the camera drive housing  105 . Camera  110  is mounted to the apex of gear  40  such that rotation of the gear  40  will cause the camera to rotate about the pan axis. Because gear  379  of pan motor  370  drives gear  40 , camera  100  is essentially driven by the pan motor  370 . Gear  40  has an annular bearing (not shown) mounted in the center thereof to permit relatively unrestricted rotation of the gear when being driven by the pan motor  370 . Furthermore, a solid shaft is used for mounting gear  379  to the pan motor platform  27 .  
         [0072]     Spacers  375  are preferably formulated to be indifferent to temperatures in the range of −40° C. to 60° C. Additionally, spacers  375  help compensate for differential thermal expansions or contractions that may occur in timing belts  56  and  57 . Timing belts  56 ,  57  with negative thermal coefficients of expansion can have adverse effects on a motor drive system having a positive thermal coefficient. Specifically, the belt tension will vary with temperature and may cause the pan and tilt motor to stall under the increased belt tension. Spacers  375  can minimize these effects. In addition to dampening motor noise, they will act as springs minimizing the variation in belt tension with temperature variation and ultimately resulting in less maintenance of the camera drive system due to complications resulting from the thermally induced loads and relaxation of the timing belts. Belt tension adjustment provided by pivoting about hole  387  ( FIGS. 14A-14C ) in platform  377 .  
         [0073]     Turning now to the software aspects of the system, the surveillance camera system in accordance with the principles of the present invention also includes an image masking system. The image masking system acts to modify a displayed image corresponding to the video signal so as to partially or totally obscure or blank the image areas or portions corresponding to one or more preselected privacy zones or masks. In accordance with the invention, a remote host computer or central control unit of the system and software programming of therein are adapted to control image masking. This control is effected based on pan, tilt and zoom coordinates associated with the privacy mask location.  
         [0074]     Each surveillance camera views an area of a location which is in the Field Of View (FOV) and along the viewing axis of the assembly. Each image is converted by the respective camera and lens assembly into an electrical video signal which is supplied to a monitor of the remote operator console over the video communications channel.  
         [0075]     The remote operator console includes a microprocessor unit, a random access memory (RAM), a FLASH memory, an encoder, a communication interface circuit and power supply. The communications interface provides bi-directional, serial communications between the operator console and a surveillance camera unit. Commands are sent to the surveillance camera unit based on operator input at the console. This input can be by a joystick, keyboard or other user control option.  
         [0076]     The remote operator console also supports a text overlay unit through which the electrical image signal passes before being displayed on the monitor. The text overlay unit, under control of the microprocessor and the software programming, generates an electrical signal containing text image information and adds the text electrical signal to the image electrical signal. This results in desired text images being overlayed on the video image so as to be visible to the operator on the monitor. These text images may include menu information and real-time status information concerning the assembly.  
         [0077]     In accordance with the principles of the present invention, the remote operator consol is further adapted to define and establish areas of the viewed video image corresponding to desired privacy zones which are to be concealed (masked) from view. In these areas, the video image is partially or totally blanked so that it is sufficiently obscured so as not to be visible or discernable to the operator viewing the video image on the monitor of the console. More particularly, these areas are established via the microprocessor and its software programming, in conjunction with an image mask, which in the present embodiment is formed by the text overlay unit.  
         [0078]     According to a preferred embodiment, a text overlay unit connected to the remote operation consol is used to develop the privacy mask. In particular, the text overlay unit is controlled by the host computer and software programming to generate a text overlay signal corresponding to blocks of semi or non-transparent characters defining an image corresponding to the privacy mask. When this overlay signal is added to the displayed image on the on screen display, the non-transparent image areas are overlayed on and totally or partially blank the associated viewed image areas. These areas (privacy zones) thus become obscured and are no longer discernible or viewable. In accordance with the invention, these image areas are established based upon defining triangular masking areas of the image.  
         [0079]     In further accord with the invention, the operator at the central location can communicate with the surveillance camera to establish the mask image areas (masks). These masks are established based on the pan, tilt and zoom information of the surveillance apparatus and are stored as non-transparent text block characters in RAM memory at either the camera&#39;s or the host computers microprocessor. They are called from RAM memory by the microprocessor and programming software and fed to the text overlay unit which combines the masks with the video image information during viewing of the scene on the on screen display.  
         [0080]     As can be appreciated, the text overlay unit, due to its ability to overlay text images on the video image, can act to mask the video images in areas where the text appears. By using blocks of semi or non-translucent or transparent characters generated by the unit, semi or non-translucent or transparent shapes can be established which tint or mask out areas of the video image. By placing these masks over the video image corresponding to the privacy zones, the video image will be partially or totally obscured in these areas, thereby concealing from sight any video images in the privacy zones.  
         [0081]     Using this capability, the microprocessor and its software programming can control the text overlay to establish and maintain the desired privacy masks. This is accomplished based on the pan, tilt and the zoom conditions of the surveillance camera and the information as to the areas of the viewed image defining the privacy masks.  
         [0082]      FIGS. 20-21  show the establishment of one such privacy mask  51  for a viewed video image on the on screen display. This is done by the operator first selecting the Program Privacy Masks item from a provided menu interface (e.g., “Program Pmask,”  FIG. 24 ). The operator marks three vertices to define the outer bounds of the privacy mask desired. Specifically, the programming software displays a cross-hair or other indicia in the center of the screen. The operator pans and tilts the surveillance camera until the cross hair is placed over the position defining a first vertex of the privacy mask. The operator then instructs the software programming to save that vertex (V 1 ). The operator then repeats this operation for the other two vertices (V 2 , V 3 ). A triangular shape is used, as this shape provides the least number of definition points to encompass an area.  
         [0083]     When all three vertices are defined, and unless an error condition is triggered and displayed indicating the privacy mask is too small or too large or the focus to far, the operator removes the cross-hair from the screen. Based on this vertex information, the programming software constructs a privacy mask and stores it in the flash memory. In particular, the software constructs a parallelogram shape, for the privacy mask by mirroring the vertex with the widest angle against the triangle&#39;s longest side, as shown in  FIGS. 20-21 . The coordinates of the area of the viewed image defined by the parallelogram are stored in a table in the flash memory as the privacy mask information. The data in this table is then used by the text overlay unit when the on screen display displays the video image to determine the text character block and whether is should be semi or non-transparent to mask the video image corresponding to the privacy zone.  
         [0084]     More particularly, during the operation of the surveillance camera system, as the surveillance device is being panned and tilted by the operator, the programming software determines first whether any privacy masks have been enabled and defined for the surveillance device. If the operator has enabled privacy masks and there are privacy masks defined, the software programming then checks the current viewing coordinates to determine whether a privacy mask is to be used to blank an area of the video image. To this end, the software programming compares the coordinates of the mask stored in the flash memory against the current displayed image field of view (FOV). If one or more masks fall within the current FOV, the programming software marks those masks as visible.  
         [0085]     If any privacy mask is marked as visible, the locations of text character blocks of the text overlay unit are checked against the coordinates of the relevant masks. A determination is then made as to whether the coordinates of a defined masks encompass one or more text character blocks. For each text character block or portion of text block that falls within the coordinates of the defined mask, text overlay unit changes the block&#39;s attribute from transparent to partially or totally non-transparent. For the mask established in  FIG. 20 , this results in blocking of the video image defined by the mask. This is shown in  FIG. 21 .  
         [0086]     As the surveillance device continues to pan, tilt and/or zoom, the programming causes changes in the pan, tilt or zoom coordinates to be monitored. In particular, the programming causes the current pan and tilt angles to be obtained for the surveillance camera. The zoom magnification is also obtained. The software programming then converts this data from the X-Y coordinate space of the surveillance camera to the coordinates of the camera&#39;s FOV. The software programming then compares the current data with the previously saved data and if there is any change, the new data is stored and a differential FOV is calculated.  
         [0087]     The changes in FOV are then applied by the software programming to redefine the text character blocks defining the one or more privacy masks. In particular, a text character block is moved right or left for changes in pan angle and up or down for changes in tilt angle. The size of the block is also changed for changes in zoom magnification. This keeps the text character block in the proper image area of the privacy mask and prevents the operator from viewing this image area. This process is repeated as the surveillance device continues to be operated so as to maintain the privacy masks concealed at all times.  
         [0088]     As can be appreciated, the text overlay unit, which can be formed from a text display microchip, must support a character background transparency or opaqueness attribute. This requires the turning on and off of this attribute on a per character basis. The unit must also support character color or border attributes so that the characters remain visible regardless of their background transparency settings. Moreover, it is preferable that the on-screen display of the unit be able to completely and uniformly mask the entire area of the video image. The character size must also provide suitable granularity to allow selectively masking parts of a video frame. Depending on the used video format the size of a single character of the unit should likely be less than 16 by 16 pixels. Using the on screen display of the remote operator consol to create and manipulate the privacy masks provides for the availability of the masks essentially independent of the specific camera model included in a surveillance camera dome. Additionally, the resolution of the privacy masks can be as high as the resolution of the on screen display. For example, an on screen display with a character set of 24 (across)×12 (down) would provide for a privacy mask with this resolution.