GB2428925A

GB2428925A - CCTV system with sensor controlled cameras

Info

Publication number: GB2428925A
Application number: GB0515236A
Authority: GB
Inventors: Keith Gough
Original assignee: Get PLC
Current assignee: Get PLC
Priority date: 2005-07-25
Filing date: 2005-07-25
Publication date: 2007-02-07
Also published as: GB0515236D0

Abstract

A CCTV system 1 comprises a plurality of cameras 2 connected to one another and each having a power supply and a sensor associated with each camera 2 and connected to a logic control unit 3 so that the power supply of each camera 2 is switched on and off in response to signals from the sensors associated with them. Preferably the sensors are Passive Infra-Red, PIR, and are permanently activated independent of camera switching. This may be achieved by supplying the sensors with their own voltage cables, each camera 2 being supplied by at least one negative and one positive voltage cable, or by supplying the sensors with one of the camera voltage cables where said cable is not switchable by the logic control unit 3. Other arrangements of cabling are also disclosed. A CCTV camera adapted to follow or track a movement object is also independently claimed.

Description

An Improved CCTV system

BACKGROUND OF THE INVENTION

The present invention relates to an improved closed circuit TV(CCTV) system. Such CCTV systems are commonly used to improve security inside buildings, car parks, and other public exposed environments.

In particular, this invention relates to a multi camera CCTV system, which may include tens or hundreds of cameras.

Each camera sends analogous images to the monitors that are normally installed remote from the cameras and usually watched by special staff sitting in a control room or monitoring centre. The cameras do not usually transmit the images at the same time. Instead they are switched on and off depending on the location of each camera and the target to be monitored.

However, in order to control the switching off and on, the system normally utilises a video switcher circuit that requires a buffer and video processing. An example of a complex system is described in WO 02056594. Due to the complexity of the video switcher circuit, the cost of using a COTV system becomes relatively expensive.

Another problem identified by the inventor is that by using such a complex video switching circuit, the probability that something goes wrong increases and the system is less reliable.

Accordingly, the present invention aims to solve all the problems mentioned above by simplifying the switcher circuit and reducing all costs of using a CCTV system.

SUMMARY OF THE INVENTION

The objective of the present invention is achieved and the above problems solved by separating the video processing from the switching circuit. The separation from the video processing allows for the production of a simpler structure of the switching circuit both in size and complexity. The switching circuit is integrated into a logic control unit together with a buffer for automatically switching the power of each CCTV camera. Furthermore, the simplicity of the logic control unit according to the present invention, results in a more reliable switch circuit with increased power efficiency due to the lack of complex digital processing.

To attain the above object, according to the first embodiment of the present invention, there is provided a CCTV system wherein a plurality of CCTV cameras are connected to each other, each camera having a power supply; and further comprising a logic control unit adapted to independently switch on and off the power supply for each camera; a buffer storing controlled information in said logic control unit; characterised by a sensor associated with each camera and connected to said logic control unit, said logic control unit being arranged to automatically switch on and off the power supply of each camera in response to signals from the associated sensor.

According to the second embodiment of the invention, there is provided a CCTV camera adapted to follow or track a moving object, connected to audio and video means for digital processing of the images and sound and to a power supply and being triggered by a sensor, characterised in that said power supply and said sensor are connected to a logic control unit adapted to automatically switch the power supply on and off in response to sensor signals.

Preferably, in the first and the second embodiments, the sensor is a FIR trigger.

Preferably, the power to the or each camera is supplied by at least one positive voltage supply cable and at least one negative voltage supply cable, the logic control unit is arranged to switch on and off one of the voltage supply cables, and the FIR trigger is supplied by an extra voltage cable.

Preferably, one of the camera voltage supply cables which is not switchable by the logic control unit supplies the FIR trigger and is permanently activated independently of the cameras switching mode.

Preferably, one of the voltage supply cables connected between each camera and the logic control unit is a main power supply for the or each camera.

Preferably, the CCTV camera and system may be supplied by two positive voltage supply cables and one negative voltage supply cable.

Alternatively, it may be supplied by two negative voltage supply cables and one positive voltage supply cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of prior art circuitry for a CCTV system according to an embodiment of the present invention.

FIG. 2 is a block diagram of the CCTV system according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, preferred embodiments of the present invention are explained with reference to the accompanying drawings.

FIG 1 shows a block diagram of a CCTV system comprising three CCTV cameras, and a video/audio buffer switcher.

Each camera has five different cables connected to the video/audio buffer switcher. These cables supply a positive voltage V+, a negative voltage V, a video and an audio output signal and a PIR trigger.

FIG 2 shows a block diagram of the CCTV system 1, according to the first embodiment of the present invention. The system comprises two or more cameras 2 connected to each other, and a logic control unit 3. Each camera 2 has six output signals but only two are connected to the logic control unit. These output signals are the camera voltage supply cable 5, which supplies the camera with a positive or a negative voltage, and the Passive Infrared Signals (PIR) trigger 4 that triggers the automatically switching on and off of the cameras 2.

The rest of the output signals are a video and an audio signal 7, a negative voltage supply cable 8 and a PIR voltage supply cable 6. The video and audio output signals are further connected to other means such as audio & video processing means, whilst the PIR voltage supply cable 6 and the negative voltage supply cable 8 are connected to a power supply. The PIR voltage supply cable is permanently activated and is not dependent of other cameras' switching mode. In order to automatically switch the cameras on and off, the PIR signals require power supply at all times.

In the second embodiment of the present invention, each camera may be incorporated with an audio or infrared sensor so that images are transmitted only if movement or sound is detected. Cameras may be adapted to follow or track a moving object or sound spot and are connected to audio and video means for digital image and sound processing.

Each camera is supplied by three voltage supply cables and triggered by a PIR trigger cable. One of voltage supply cables is a PIR voltage supply cable which is permanently activated and is not dependent of other cameras' switching mode. The remaining voltage supply cables are either both negative voltage signals or one of them is a negative voltage signal. Further, one of these voltage supply cables is a main power supply and is connected to a logic control unit so the camera can be controlled by the power supply.

Of the remaining voltage supply cables, one is a negative voltage supply cable and the other is either negative or positive and one of said voltage supply cables and said PIR trigger cable are connected to a logic control unit, switching the power on and off automatically.

Further, although the first embodiment has only illustrated PIR signals, the trigger signals are not limited to infrared signals and other kind of signals such as audio signals can be employed.

Claims

1. A CCTV system wherein a plurality of CCTV cameras are connected to each other, each camera having a power supply, and further comprising a logic control unit adapted to independently switch on and off the power supply for each camera; a buffer storing controlled information in said logic control unit; characterised by a sensor associated with each camera and connected to said logic control unit, said logic control unit being arranged to automatically switch on and off the power supply of each camera in response to signals from the associated sensor.

2. A CCTV system according to claim 1, where each sensor is a PIR trigger.

3. A CCTV system according to claim 2, wherein the power to each camera is supplied by at least one positive voltage supply cable and at least one negative voltage supply cable, the logic control unit is arranged to switch on and off one of the voltage supply cables, and the PIR trigger is supplied by an extra voltage cable.

4. A CCTV system according to claim 3, wherein one of the camera voltage supply cables which is not switchable by the logic control unit supplies the PIR trigger and is permanently activated independently of the cameras switching mode.

5. A CCTV system according to claims 3 or 4, wherein the said extra voltage supply cable connected between each camera and the said logic control unit is a main power supply for each camera.

6. A CCTV system according to any one of claims 3 to 5, wherein each camera is supplied by one negative voltage supply cable, and two positive voltage supply cables, and one of the positive voltage cables is said extra voltage cable.

7. A CCTV system according to any one of claims 3 to 5, wherein each camera is supplied by one positive voltage supply cable and two negative voltage supply cables, and one of the negative voltage supply cables is said extra voltage cable.

8. A CCTV camera adapted to follow or track a movement object, connected to audio and video means for digital processing of the images and sound and to a power supply and triggered by a sensor, characterised in that said power supply and said sensor are connected to a logic control unit adapted to automatically switch the power supply on and off in response to sensor signals.

9. A CCTV camera according to claim 8, where the sensor is a PIR trigger.

10. A CCTV camera according to claim 9, wherein the power to the camera is supplied by at least one positive voltage supply cable and at least one negative voltage supply cable, the logic control unit is arranged to switch on and off one of the voltage supply cables, and the PIR trigger is supplied by an extra voltage cable.

11. A CCTV camera according to claim 10, wherein one of the camera voltage supply cables which is not switchable by the logic control unit supplies the FIR trigger, and is permanently activated independently of the camera switching mode.

12. A CCTV camera according to claims 10 or 11, wherein the said extra voltage supply cable connected between each camera and the said logic control unit is a main power supply for each camera.

13. A CCTV camera according to any one of claims 10 to 12, supplied by one negative voltage supply cable and two positive voltage supply cables, where one of the positive voltage supply cables is said extra voltage cable.

14. A OCTV camera according to any one of claims 10 to 12, supplied by one positive voltage supply cable and two negative voltages supply cables, where one of the negative voltage supply cables is said extra voltage cable.