IMPROVEMENTS RELATING TO SURVEILLANCE SYSTEMS

Abstract: A surveillance system for use in a public building which comprises a carriage means adapted to travel along the track, the carriage means being provided with a suitable detection means for monitoring an environment adjacent the track and for generating corresponding detection signals which are transmitted to a remote receiving station via the track on which the carriage travels. In this way the carriage is able to follow a circuitous route and further the track is able to transmit a plurality of signals.

Description: Improvements Relating to Surveillance Systems The present invention relates to surveillance systems and more particularly to systems of the type comprising cameras carried along hidden tracks for use in public buildings. In existing security systems such as that disclosed in British Patent No 1517386, a camera mounted on a carriage is moved on an elongate track by means of a pulley system driven by an electric motor. This type of system has the disadvantage on that the camera must tow the pulley cable behind it along the track and so because of the problems associated with arranging cables and wires to pass around curves and bends, the system is limited to use with straight tracks which obviously restricts the use of the invention since in many instances it is desirable to have a single surveillance system running around an entire building rather than several individual straight tracks. Further, in present surveillance systems the signal from the camera is transmitted to an imaging means such as a video display unit along cable which means that if the cable is damaged and broken it is often difficult to locate the precise position of the fault in order to repair or replace a section of the cable. It can therefore be seen that there is a need to provide a surveillance means which is not attached to a propelling unit or video display by means of cabling or the like. It will be understood that if this can be achieved then it will be possible to provide a relatively free-standing surveillance system which is able to travel along a track in an unrestrained manner and in any chosen direction. Although it is known that it is possible to motorise a free- standing surveillance means such as a carriage and thus enable it to travel along a predetermined track it is difficult to transmit the signal from the camera or other detection means through free space back to a video receiver. This is because of the wave length required to transmit the video signal which results in problems of interference and also there are problems concerning adherence to strict radiation standards especially where a signal has to travel a considerable distance through free space since under these circumstances it is necessary to transmit a significantly powerful signal. As a result of this surveillance systems have been manufactured with a fixed cable means for relaying signals. However, the invention provides a means of transmitting a video signal which overcomes the aforementioned restrictions. According to the present invention there is therefore provided a surveillance system comprising a carriage means adapted to travel along a track, the carriage supporting a detection means for producing a signal transmittable to a remote receiving station wherein the track along which the carriage travels serves as a transmission line for the signal. It will therefore be understood that since the signal is transmitted along the track there is no longer a need for any cabling to be attached between the camera and the signal receiver. Furthermore, since the signal is transmitted along the track problems associated with radiation levels are overcome and an essentially unattenuated signal is received by the signal receiver. Preferably the track is adapted for optimum transmission of the video signal. Preferably the track is made of copper. Preferably the detection means is a camera. Preferably the signal is a video signal. Preferably a coupling network is provided to enable the signal to be transferred and transmitted along the track. Preferably the carriage is provided with coupling means in the form of carbon brushes or the like which conduct signals travelling along the track and so transfer the said signals from the track to a predetermined location. Preferably the carriage is powered by an electric motor and more preferably the energy to power the electric motor is transmitted along the track. Preferably the camera located on the carriage is controlled by a remote operating means. Preferably control signals from the remote operating means are transmitted to the camera via the track. Preferably the carriage is provided with at least one light sensor so as to detect when the carriage is travelling through a tunnel, passage or the like. Preferably the at least one light sensor is coupled to a means for rotating the camera so that when the carriage travels through the said tunnel the camera can be rotated so as to view a preselected area when the carriage emerges from the said tunnel. Preferably the carriage is provided with braking means which are adapted to decellerate the carriage as it approaches the end of a straight run of track. Preferably the braking means comprises a light sensing means located on the carriage and a light reflecting means located on or towards the end of a straight run of the track so that as the carriage approaches the light reflecting means, the light sensing means is activated and a braking means is in turn activated. According to a further aspect of the invention there is provided a surveillance system comprising a carriage means supporting a detection means, and a track along which the carriage travels wherein the track is adapted to transmit a plurality of signals so as to: control the movement of the carriage on the track, control the operational status of the detection means on the carriage and to transmit a signal from the detection means to a remote receiving station. According to a further aspect of the invention there is provided a surveillance system comprising a carriage means supporting a detection means, the carriage being adapted to travel along a predetermined track whereby the carriage is able to follow a circuitous route. It will be understood that once the carriage is unencumbered of cabling and the like it is free to travel in any desired or pre-programmed direction. Preferably the detection means comprises at least one camera. Preferably a plurality of carriages will be coupled so as to travel in numbers around the track. Preferably each of said coupled carriages will perform a different funtion. Preferably the carriage and track is concealed within a housing, the housing being provided with at least one face comprising preferably a one-way mirror. Preferably the carriage is further provided with heat sensing means so as to detect the presence of an individual in an environment or to detect the presence of fire. Preferably the carriage is further provided with a smoke sensing means. A single embodiment of the invention will now be described by way of example only with reference to the accompanying drawings wherein:- Figure 1 is a plan view of a surveillance system according to the invention; Figure 2 is a side view of a carriage carrying a camera; and Figure 3 is a front view of the carriage shown of Figure 2 and Figures 4 and 5 show diagrammatically the signal transmission scheme employed in the invention. Turning firstly to Figure 1, the surveillance system of the present invention comprises a duct 10 which may run for example around the whole perimeter of a supermarket, factory, warehouse, football stadium or the like. It is of note that the duct is not straight but has bends or curves 12. With reference to Figure 3 it can be seen that the duct is formed from a rigid material such as steel and has a window 14 on a first side A of the duct 10. Window 14 runs along the entire length of the duct and is inset into front wall 16. Window 14 is formed from one-way glass or a similar material so that an observer cannot see inside duct 10 but a viewing means located inside the duct can view the environment through window 14. Positioned within the duct 10 is a carriage 18 on which is mounted camera 20. Each carriage 18 may carry more than one camera 20 in order to obtain a better view of any situation. The cameras are orientated so that they survey the environment surrounding the duct 10 through window 14. Carriages 18 are further provided with an electric motor 22 for powering same. Electricity is supplied to the motors 22 by means of conducting rails or track 24. Rails 24 are evenly spaced along their length and run the entire length of duct 10. Turning now to Figure 2, a first carriage 18 is provided with depending carbon brushes 26 at its front end X. Brushes 26 form an electrical contact with track 24. This is also seen in Figure 3. Carriage 18 is further provided with a single wheel 28 which lies between brushes 26 at the front end of the carriage. The carriage 18 may also be provided with additional pairs of brushes 30 along its length to ensure that electrical contact with rails 24 is constantly maintained. Carriage 18 is also provided with additional stabilising wheels 52. Carriage 18 may further be coupled to a second carriage 19 by means of coupler 42. Carriage 19 is also provided with a camera 20 but may or may not be provided with a motor 22. This coupled arrangement has the advantage that two different views may be obtained of the same incident since cameras 20 are in slightly different positions. Alternatively, one of the cameras could be used to take a long distance shot while the other could be zoomed in order to record details. Cameras 20 are provided with zoom tilting and panning facilities in order to enhance the functioning of the surveillance systems. In operation therefore, an operator at a remote controll centre can select a location in which he wishes a camera to be positioned and can transmit to the carriage 18 an instruction to move to that location. Once in position camera 20 on carriage 18 can be operated to show a picture of the areas surrounding the camera. The operator can select the type of operation required and transmit the necessary instructions to each of the cameras 20. Information from the camera is transmitted to the remote control centre via the track which functions as a transmission line. The means by which signals are sent in the surveillance system will now be described by reference to Figures 4 and 5. Referring firstly to Figure 4 a remote control station 50 is provided with an operating means for controlling the operational status of a camera 20 located on a remote carriage 18. As illustrated in Figure 4 camera 20 may be controlled so as to enable panning, tilting, focusing or zoom to be controlled. Further, there is provided a driving means for controlling the motion of carriage 18 and also any other means which are considered to be suitable for operation of the surveillance system. An operating device such as a push button or joy stick is connected to an Interface and Channel Multiplexer so that operation of a pre-selected operating device is detected by the Multiplexer and a suitable pulse signal is generated. It will be understood that the nature of the signal generated will be determined by the nature of the operation to be performed. To enable the signal to be transmitted to the corresponding device, such as the camera, the signal generated by the multiplexer modulates a carrier signal of 42 MHz supplied by oscillator 4. The form of modulation used is either pulse width or frequency modulation or frequency shift keying or any other suitable means known to those skilled in the art. A filter 5 is used to eliminate unwanted signals before the pulse signal is transmitted to a coupling network 6. The coupling network 6 connects the signal onto the track 24 for transmission along the track and the impedance of the track 24 is matched by the coupling network so as to avoid losses or reflections which result in standing waves forming on the line. At a variable distance along track 24 there is provided mounted on carriage 18 a second coupling network 8 which picks up the transmitted signal via carbon brushes 26 depending from carriage 18. The signal is passed through a suitable demodulating circuit to recover the original information; the demodulating circuit comprising a local oscillator 11 and a demodulator 12 and filter 13 for elimination on unwanted radio frequencies. The demodulated signal then passes to a Channel Demultiplexer 14 where the signal is converted from a pulse signal to a voltage signal and so exists in exactly the same state as it was generated by the Mulitiplexer 2. The Channel Demultiplexer 14 feeds the signal for example to a circuit controlling operation of camera pan and so brings about panning of the camera. It will be understood that other controlling signals having a predetermined pulse signature are similarly transmitted along the track 24 in order to bring about a predetermined result in the operational status of the camera. Similarly, signals for driving the motor 22 attached to carriage 18 are also transmitted via track 24 following passage through coupling network 6. This signal activates the motor 22 and power for operation of the motor 22 is derived via a 24 volts supply provided in track 24. Referring now to Figure 5 camera 22 (not shown) provides a video input signal which may be either colour or black and white as indicated at 20. In order to transmit the video signal along track 24 the video signal is modulated on a carrier frequency of 192 MHz. This is brought about by means of circuitry indicated by references 22 and 24. Filter 42 is provided to eliminate unwanted signals. The modulated signal is fed to a coupling network 8 and transmitted along track 24 via carbon brushes 26 depending from carriage 18. At a variable distance from coupling network 8 coupling network 6 picks up the modulated video signal and transfers it to the demodulating circuit shown in Figure 4 which comprises filter 30 to eliminate unwanted frequencies, and local oscillator 32 and phase locked loop 34. Oscillator 32 and phase locked loop 34 are used in conventional manner to demodulate the signal in order to reconstitute the video signal. The demodulated signal appears at 35 before a final amplification and filtering step at 36. The video output signal 38 is equal to the video input signal 20. The video output signal is now fed to a monitor for viewing. If required, carriage 18 may also be provided with heat sensors and smoke sensors which may also be controlled so as to selective orientate with respect to the carriage so as to efficiently scan a predetermined area. The signals for controlling the sensors and relaying information are transmitted in the afore described fashion. Although not shown in the figures, it is intended, that the carriage will be provided with a light sensing means and the inside of a housing in which the surveillance system is located is provided with light reflecting means positioned at predetermined locations so that as the carriage approaches a passage or tunnel or the like the light sensing means will detect light from the light reflecting means and a signal can be sent to the detection means so that it may be orientated accordingly during the time that the carriage is in the tunnel and also for when the carriage emerges from the tunnel. Further, it is intended that a light sensing means is coupled to a braking means so that as the carriage approaches the end of a straight run of track light reflectors on the inside of the housing accommodating the surveillance system will signal the end of the run of track to the light sensing means which in turn will be coupled to a braking device so as to slow down the carriage. It will be understood that although the embodiment has been described using a single detection means in the form of a camera the invention lies in a surveillance system which may use other forms of detection means and the way in which information is transmitted throughout the surveillance system. It can therefore be seen by means of the information disclosed above that signals for controlling the operational status of the camera the functioning of the motor and the image shown on a video monitor are fed between a moveable carriage and remote control centre via a single track 24. The surveillance system therefore provides an efficient and flexible means of monitoring a public building.

Claims: CLAIMS 1. A surveillance system comprising a carriage means adapted to travel along a track, the carriage supporting a detection means for monitoring an environment and producing corresponding signals transmittable to a remote receiving station wherein the track along which the carriage travels serves as a transmission line for the signals. 2. A Surveillance system according to claim 1 wherein the detection means comprises a camera. 3. A surveillance system according to claim 1 wherein the detection means comprises a heat sensor. 4. A surveillance system according to claim 1 wherein the detection means comprises a smoke detector. 5. A surveillance system according to claim 1 wherein the track is adapted for optimum transmission of the signal. 6. A surveillance system according to claim 1 or 5 wherein the track is made of copper. 7. A surveillance system according to claim 2 wherein the signal is a video signal. 8. A surveillance system according to claim 1 wherein a coupling network is provided to enable the signal to be transferred and transmitted along the track. 9. A surveillance system according to claim 1 wherein the carriage is provided with coupling means in the form of carbon brushes or the like. 10. A surveillance system according to claim 1 wherein the carriage is powered by an electric motor. 11. A surveillance system according to claim 10 wherein the energy to power the electric motor is transmitted along the track. 12. A surveillance system according to claims 1, 2, 3 or 4 wherein the operational status of the detection means is controlled by a remote operating means. 13. A surveillance system according to claim 12 wherein signals from the remote operating means is transmitted to the detection means via the track. 14. A surveillance system according to claim 1 wherein the carriage is provided with a light sensor. 15. A surveillance system according to claim 14 wherein the light sensor is coupled to a rotating means so that the detection means can be selectely orientated when the carriage passes through a tunnel. 16. A surveillance system according to claim 14 wherein the light sensor is coupled to a braking means so as to decellerate the carriage as it approaches the end of the straight run of track. 17. A surveillance system according to claim 16 wherein a light sensing means located on the carriage co-operates with the light reflecting means located adjacent the surveillance system so that at the end of the straight run of track light reflected from the light reflecting means is detected by the light sensing means to bring about activation of a braking means. 18. A surveillance system according to any preceding claim wherein a plurality of carriages are coupled together. 19. A surveillance system according to claim 18 wherein at least some of the said carriages perform a different function. 20. A surveillance system according to any preceding claim wherein the system is located within a housing. 21. A surveillance system according to claim 20 wherein at least one side of the housing is provided with a face that can be viewed through. 22. A surveillance system according to claim 21 wherein the face comprises a one-way mirror. 23. A surveillance system comprising a carriage means supporting a detection means, and a track along which a carriage travels wherein the track is adapted to transmit a plurality of signals. 24. A surveillance system according to claim 23 wherein the track transmits a signal so as to control the movement of the carriage. 25. A surveillance system according to claim 23 wherein the track transmits a signal so as to control the operational status of the detection means. 26. A surveillance system according to claim 23 wherein the track transmits a signal from the detection means to a remote receiving station. 27 . A surveillance system comprising a carriage means supporting a detection means , the carriage means being adapted to travel along a predetermined track whereby the carriage is able to follow a circuitous route .

Inventors: WESTON DENNIS, WESTON, DENNIS
Applicants: TV SECURITY LIMITED
Application year: 1991
Main classification: G08B13
IPC codes: G08B13