Abstract:
A remote controlled television monitoring system for day and night monitoring includes a camera unit in the form of a housing having first and second cameras. The first camera principally monitors during daylight conditions; while the second camera monitors during low light or night conditions. The second camera preferably has a high low light sensitivity. Both of the cameras have automatic iris over ride for manual control of the camera iris. Each of the cameras optionally has an azimuth generator to indicate angular position of the camera. An adjustable zoom lens is coupled to each of the cameras. In one aspect, a light intensifier is coupled between the lens and the second camera for intensifying light received by the second camera. The light intensifier preferably has internal automatic brightness control.

Description:
BACKGROUND OF THE INVENTION 
     1. Field Of The Invention 
     The present invention relates, in general, to remote controlled, closed circuit television monitoring systems and, in particular, to television monitoring systems which are capable of both day and night operation. 
     2. Description of the Art 
     In closed circuit monitoring systems, one or more cameras are contained within a housing which is either stationarily mounted on a fixed bracket or attached to a pan/tilt apparatus for panning and elevational movements to cover a wide field of vision. A typical television monitoring system is shown by the Applicant&#39;s U.S. Pat. No. 4,293,876 and includes a dual channel camera unit, a transmitter or controller and a receiver. The camera unit includes a color daylight camera, a low light camera, a light intensifier coupled to the low light camera and a channel control circuit. The channel control circuit provides automatic switching between the daylight and the low light cameras in response to variations in the ambient light intensity. 
     While this monitoring system has proven to be an effective surveillance device, it would be desirable to provide an enhanced monitoring system which takes advantage of recent camera developments so as to improve visual resolution under low light conditions. 
     SUMMARY OF THE INVENTION 
     The present invention is a television monitoring system operative during both daylight and low light or night conditions. 
     The television monitoring system includes a camera apparatus formed of a first camera for monitoring principally during daylight conditions and a second high sensitivity low light camera for monitoring principally during low light or night conditions. At least one and preferably both of the first and second cameras have automatic iris override for selective control of the camera iris. A control circuit is provided for selectively energizing, utilizing and de-energizing the first and second cameras in response to a predetermined variation in ambient light intensity so that only one of the first and second cameras is energized in daylight or night at one time. 
     Optionally, at least one and, preferably, both of the first and second cameras have an azimuth generator which provides an output indicative of the position of the camera. 
     In one embodiment, the second camera is a CCD camera with a high low light sensitivity of substantially 0.08 lux. 
     Further, each of the first and second cameras is provided with an adjustable zoom lens. In one embodiment, a light intensifier is coupled between the zoom lens and the second camera for intensifying the light received by the second camera. The light intensifier has automatic brightness control for improved contrast. 
     The camera unit of the present television monitor apparatus provides enhancements over previously devised television monitoring systems. The camera unit takes advantage of improvements in camera design which enable automatic override of the camera iris for better brightness control or contrast as well as to change the focal length of the camera for specific viewing of a predetermined object or portion of a surveillance area. 
     Small sized cameras may be employed to reduce the overall size of the camera apparatus enclosure. An optional azimuth generator can be utilized on either or both of the cameras to provide an indication of the position of the cameras. This can be compared with the selected azimuth of the pan/tilt unit to determine the position of the camera apparatus. 
     While the camera apparatus of the present invention provides the aforementioned advantages, the camera apparatus still retains the standardized single video output and single control cable input to the camera apparatus as required in the monitoring industry. This enables the camera apparatus to be employed with any industry standard remote camera controller, control signal transmitter and receivers, and pan/tilt units. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features, advantages and other uses of the present invention will become more apparent by referring to the following detailed description and drawing in which: 
     FIG. 1 is a pictorial representation of a television monitoring apparatus according to the present invention; 
     FIG. 2 is a plan elevational view of one embodiment of the dual channel camera unit shown in FIG. 1; 
     FIG. 3 is a schematic diagram of the logic circuit employed in the camera unit shown in FIG. 2; 
     FIG. 4 is a plan elevational view of another embodiment of the camera unit of the present invention; 
     FIG. 5 is a side elevational view of another embodiment of the television monitoring apparatus of the present invention; and 
     FIG. 6 is a pictorial representation of the components of the television monitoring apparatus shown in FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, the present invention is a television monitoring apparatus  10  which includes a dual channel camera unit  12 , a pan/tilt unit  14 , a receiver  16 , a transmitter or controller unit  18  and a television monitor  20 . 
     The operation of the camera unit  12  and the pan/tilt unit  14  is controlled by the transmitter/controller  18 . Control signals are sent from the transmitter  18  through a cable  22  to the receiver. The signals are then processed and sent to the various video control circuits in the pan/tilt unit  14  and the camera unit  12 . Although a cable is preferable for connecting the transmitter  18  to the receiver  20 , other communication techniques, such as radio frequency signals, etc., may also be employed. 
     The video output signal from the camera unit  12  is transmitted by a cable  24  to the remotely located television monitor  20 . Any suitable television monitor  20  may be employed. Preferably, the TV monitor  20  is a video monitor which provides 300 lines of color and 450 lines black and white video. 
     The receiver  16  and the transmitter/controller  18  are conventionally available receiver and controller units, such as a receiver, model number KTD-125 and a transmitter/controller, model number KTD-304, both manufactured by Kalatel, Inc. 
     As is conventional, the controller  18  contains a number of push buttons which control the application of electrical power to the camera unit  12  as well as an auto/manual joystick which can be operated in conjunction with one of the push buttons to control the speed and direction of pan movement of the pan/tilt unit  14 , and the speed and direction of movement of the tilt mechanism pan/tilt unit  14  during manual operation. 
     In automatic mode, the pan/tilt unit  14  sweeps or pans the camera unit  12  right and left within the boundaries determined by adjustable limit switches or other limit stops contained in the pan/tilt unit  14 . During such pan movements, the tilt or elevation of the camera unit  12  remains constant after having been set by the user for a particular application. As is conventional, the pan/tilt unit  14  is capable of panning from 0° to 340° horizontally and tilting from 45° above and 45° below horizontal. 
     Other push buttons on the controller  18  provide zoom, focus and iris opening controls for both cameras in the camera unit  12 . 
     Referring now to FIG. 2, there is depicted one embodiment of the dual channel camera unit  12  which in the form of a closed housing  30 . The housing  30  has a generally rectangle configuration, by example only, which is formed of four sidewalls and opposed first and second ends  32 ,  34 , respectively. A face plate  36  is mounted in the first ends  32  of the housing  30  to provide a viewing port for the cameras mounted within the housing  30  as well to protect the cameras from moisture, dirt, wind, etc. Inside the face plate is a mask  52  which outline the lenses and reduces spurious light. 
     The dual camera unit  12  according to one aspect of the present invention is a dual channel design which includes one color camera  38  with digital signal processing. Preferably, the color camera  38  is a CCD camera. The color camera  38  is provided with an auto iris motorized zoom lens  40  with presets. By example only, the zoom lens  40  may have an apparent focal length of 30-180 mm. Further, the color camera  38  has a light sensitivity of approximately 2 lux with digital processing and backlight compensation. 
     The camera unit  12  also includes a black/white, high sensitivity camera  42  which is mounted in the housing  30  by a mounting bracket  43 . The black/white camera  42  is also provided with a motorized zoom lens  44  which has digital presets for night or low light operation. The zoom lens  44  may be any suitable zoom lens, such as a zoom lens having an apparent focal length of 30-180 mm. The camera  38  and  42  are mounted via brackets  39  and  43  to an elongated mounting bracket  45  which extends longitudinally along the length of the housing  30 . A small fan  46  is also mounted within the housing adjacent the second end  34 . A logic or control circuit  48  on a printed circuit board is also mounted adjacent the second end wall  34  of the housing  30 . The logic circuit  48 , as shown in FIG. 4, provides connection between the pair of control cables from the receiver  16  and the coax video output cable  24 . In accordance with industry standards, only one coax cable and one control cable is connected to the camera unit  12 . The logic board  48  functions to sense change in voltage from a photo cell to accomplish video output from either day or night camera and controls for the operation of the motorized zoom lenses via relays, and supply power for the intensifier  50 . 
     Individual conductors, not shown, extend from the logic circuit  48  to each of the cameras  38  and  40  as well as to the motorized zoom lenses  40  and  44 , the fan  46  and to an optional heater, not shown. The logic circuit  48  accepts inputs from the receiver  16  as well as provides outputs to the receiver  16  to enable control of each camera  38  and  42 , the automatic switching between the two cameras  38  and  42  in response to ambient light conditions as detected by a photocell  47  mounted on the receiver  16 . The logic circuit  48  also combines the individual video output of the day color camera  38  and the night black/white camera  42  into a single video output to the monitor  20 . 
     FIG. 4 depicts an alternate embodiment of the dual camera unit  12 ′ in which the same color camera  38  with digital signal processing as in the first embodiment described above is mounted. The auto iris motorized zoom lens  40  is also employed with the color camera  38 . 
     This embodiment also includes one black/white high sensitivity camera  42  and the auto iris motorized zoom lens  44 . However, in this embodiment of camera unit  12 ′, a third generation light intensifier with auto bright control  50  is coupled between the black/white camera  42  and the output end of the zoom lens  44  for intensifying light received by the camera  42 . 
     Otherwise, the camera unit  12 ′ shown in FIG. 4 is identical to the camera unit  12  shown in FIG. 2 in that a logic or control circuit  48  is mounted within the housing  30  to control the operation of the cameras  38  and  42 , the zoom lenses  40  and  44 , the fan  46  and the heater, not shown. 
     In this embodiment, the light intensifier  50  increases the light sensitivity of the black light, night camera  42  under night or low light conditions to 0.00001 lux. 
     Both of the cameras  38  and  42  in either embodiment may be any suitable CCD cameras, such as color and black/white cameras sold by Panasonic. 
     Either or both cameras, including the color  38  camera and the black/white camera  42  in either embodiment are also provided with certain features, such as an azimuth generator and an auto iris override. 
     The auto iris override feature of the cameras  38  and  42  provides automatic iris control via through the lens metering. Control signals from the controller  18  are provided to each camera  38  or  42  to control the iris diameter and thereby the field of view of the camera  38  or  42 . This enables a user to adjust the iris diameter for proper lighting and contrast as well as to enable the camera  38  and  42  to clearly focus up close on an object within the field of view of the camera  38  or  42 . 
     Manual control of auto iris is accomplished by adding a relay into the lens. The remote function requires three positions: 1) auto, 2) manual, and 3) normal. 
     Both cameras  38  and  42  and the logic circuit  48  are capable of receiving signals from the controller  18  to manually select either day or night cameras  38  or  42  for operation at any time. Although high intensity lighting must be avoided when using the black/white, intensified night camera  42 , the ability to manually select day or night camera operations could be useful at dusk, dawn or in other low light conditions, such as during a storm, or where the camera unit  12  is used inside a building and the user decides to improve monitoring capabilities by selecting either of the color camera  38  or the black and white camera  42  for immediate operation. 
     Finally, each camera  38  and  42  is provided with a video azimuth generator which provides a video character as a separate output signal from the receiver  16  to a display on the controller  18 . This enables a user to determine the exact position of the camera  38  or  42 . This position display can be compared with a display on the controller  18  set by the individual switches or push buttons on the controller  18  which establishes the tilt or angle of elevation of the camera unit  12 . 
     Referring now to FIGS. 5 and 6, there is depicted another camera apparatus  60  in which the color day camera  38  and the high sensitivity black/white, night camera  42  are mounted within a spherical dome enclosure  62 . 
     The dome  62  may be any suitable enclosure, such as a Superdome housing, model numbers SDP16 or SDW16, Detection Systems &amp; Engineering Company, Troy, Mich. The dome  62  includes an integral pan/tilt assembly  64  which is mounted within an opaque, upper hemispherical portion or housing  66 . A tubular sleeve  68  extends through the upper portion  66  and carries the cables to the camera unit mounted within the dome  62 . The sleeve  68  may also be formed part of or be attached to a separate mounting bracket on a stationary fixture, pole, etc. 
     A turntable  70  is rotatably mounted on the sleeve  68  and driven by the pan drive motor and a bracket  72  coupled to the turntable  70  and having a yoke extending downward therefrom. A pivot axis is formed on the yoke  72  on which a tilt drive motor  74  is mounted along with mounting brackets carrying the cameras  38  and  42 . 
     As shown in FIG. 6, a receiver circuit  76  is mounted to one side of the yoke or bracket  72 . The receiver circuit  76  may be a Kalatel receiver model number KTD128 for receiving signals from the transmitter/controller  18 . 
     The dome receiver  76  is inboard of the housing and provides the same control function for pan, tilt, and zoom as the outboard controller. For service simplicity, these are kept separate in the dome. 
     The logic circuit  78 , shown generally in FIG. 6 is mounted to one leg of the bracket  72 . 
     The receiver circuit  76  controls power to the pan and tilt drive motor of the pan/tilt as well as the zoom and auto focus signals to the cameras  38  and  42 . The logic circuit  78  also provides RS422 communication to the controller  18 . 
     A lower hemispherical portion  80  is also provided as part of the dome  62 . The lower hemispherical portion  80  is rotatable with respect to the upper hemispherical portion  66 . A bracket is connected between the turntable  70  and the lower hemispherical portion  80  to simultaneously rotate the lower hemispherical portion  80  with scanning movements of the cameras  383  and  42 . 
     The lower hemispherical portion  80  may be formed of a dark opaque plastic which prevents an observer from easily detecting the direction of focus of the cameras  38  and  42 . The lower hemispherical portion  80  is provided with an elongated slot, not shown, extending from the lowermost pole toward the upper edge of the lower hemispherical portion  80 . This slot, not shown, is aligned with the lenses  40  and  44  attached to the cameras  38  and  42  and provides a covered opening defining the field of view of the cameras  38  and  42 . 
     An azimuth circuit, not shown, resides in the receiver for both dome and conventional modules.