Low power video security monitoring system

What is claimed is:

1. A video security monitoring system comprising:

a video camera for producing a video signal from an image of an area viewed by a lens of said video camera, said video camera including an iris control;

a digital video image compression subsystem for receiving the video signal from said video camera, for digitally processing the video signal to determine if any motion is occurring in the area viewed by the lens of said video camera, for converting the video signal into compressed digital video data that provides an image of the area viewed by the lens of said video camera, and for transmitting the compressed digital video data;

a digital signal transmission interface and control for controlling operation of said video camera and said digital video image compression subsystem, for receiving the compressed digital video data from said digital video image compression subsystem, and for transmitting the compressed digital video data from said video security monitoring system to a remote video monitoring facility via a communication channel if said digital video image compression subsystem determines that motion has occurred in the area viewed by the lens of said video camera, said digital signal transmission interface and control also managing power consumption by said video security monitoring system by causing said video camera and said digital signal image compression subsystem to operate at a slower clock speed when motion is not present in the area viewed by the lens of said video camera and to operate at a faster clock speed upon detecting motion in the area viewed by the lens of said video camera; and

a camera controller for effecting changes in settings of the iris control of said video camera to compensate for changes in video camera sensitivity resulting from operation of said video camera at different clock speeds in effecting power management of said video security monitoring system.

2. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control transmits the compressed digital video data from said video security monitoring system via an ISDN basic access communication channel.

3. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control transmits the compressed digital video data from said video security monitoring system via an ISDN primary access communication channel.

4. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control transmits the compressed digital video data from said video security monitoring system via an analog signal communication channel.

5. The video security monitoring system of claim 4 wherein said digital signal transmission interface and control further includes a modem for transmitting the compressed digital video data from said video security monitoring system via the analog signal communication channel.

6. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control receives electrical power for energizing operation of said video security monitoring system from the communication channel.

7. The video security monitoring system of claim 6 further comprising a power supply for adapting electrical energy received from the communication channel for energizing the operation of electronic circuits included in said video camera, said digital video image compression subsystem, said digital signal transmission interface and control, and said camera controller.

8. The video security monitoring system of claim 7 wherein said power supply also stores electrical energy for energizing operation of said video security monitoring system.

9. The video security monitoring system of claim 8 wherein said power supply stores electrical energy in a battery.

10. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control transmits the compressed digital video data from said video security monitoring system via an optical fibre communication channel.

11. The video security monitoring system of claim 1 wherein said digital signal transmission interface and control broadcasts the compressed digital video data from said video security monitoring system via a wireless communication channel.

12. The video security monitoring system of claim 1 wherein said video camera further includes a focus control, and said camera controller effects changes in settings of the focus control responsive to control signals received from said digital signal transmission interface and control.

13. The video security monitoring system of claim 1 wherein said video camera further includes a zoom lens, and said camera controller effects changes in settings of the zoom lens responsive to control signals received from said digital signal transmission interface and control.

14. The video security monitoring system of claim 1 wherein said camera controller tilts said video camera responsive to control signals received from said digital signal transmission interface and control.

15. The video security monitoring system of claim 1 wherein said camera controller pans said video camera responsive to control signals received from said digital signal transmission interface and control.

16. The video security monitoring system of claim 1 further comprising a serial control for exchanging digital signals between said digital signal transmission interface and control and a monitoring device external to said video security monitoring system.

17. The video security monitoring system of claim 16 wherein said monitoring device transmits signals to said video security monitoring system responsive to atmospheric conditions.

18. The video security monitoring system of claim 1 further comprising a compressed data memory for temporarily storing compressed digital video data transmitted from said digital video image compression subsystem.

19. The video security monitoring system of claim 18 wherein said compressed data memory retains compressed digital video data stored therein even after interruption of all electrical power that energizes operation of said video security monitoring system.

20. The video security monitoring system of claim 19 wherein said compressed data memory stores compressed digital data on a magnetic recording device.

21. The video security monitoring system of claim 19 wherein said compressed data memory stores compressed digital data in a FLASH semiconductor memory.

22. The video security monitoring system of claim 1 further comprising a strobe light for momentarily illuminating the area viewed by the lens of said video camera.

23. The video security monitoring system of claim 22 wherein said strobe light emits a pulse of light respensive to a signal received from said digital signal transmission interface and control.

24. The video security monitoring system of claim 22 wherein said strobe light emits a pulse of light responsive to a signal received from said digital video image compression subsystem.

25. The video security monitoring system of claim 1 further comprising a light emitting stylus that emits light directed toward the lens of said video camera for presenting an image indicating motion of said stylus to said video camera.

26. The video security monitoring system of claim 1 further comprising:

a microphone for producing an audio signal from sound occurring about said video security monitoring system; and

a digital audio compression subsystem for receiving the audio signal from said microphone, for digitally processing the audio signal to determine if any change in sound has occurred about said video security monitoring system, for converting the audio signal into compressed digital audio data of sound occurring about said video security monitoring system, and for transmitting the compressed digital audio data to said digital signal transmission interface and control.

27. The video security monitoring system of claim 1 further comprising:

a digital audio decompression subsystem for receiving compressed digital audio data from said digital signal transmission interface and control, for converting the compressed digital audio data into an audio signal, and for transmitting the audio signal; and

a speaker for receiving the audio signal from said digital audio decompression subsystem and producing an audible sound therefrom.

28. A method for operating a video security monitoring system, the video security monitoring system including a video camera and a digital video image compression subsystem that are fabricated using digital circuits which operate in response to a clock signal, said method comprising the steps of:

providing a slow clock signal to the digital circuits included in the video security monitoring system whereby the video security monitoring system requires a low amount of electrical power;

producing a video signal from an image of an area viewed by a lens of the video camera and transmitting the video signal to the digital video image compression subsystem;

digitally processing the video signal in the digital video image compression subsystem to determine if any motion is occurring in the area viewed by the lens of the video camera;

if motion is detected in the area viewed by the lens of the video camera, providing the digital circuits included in the video security monitoring system with a faster clock signal thereby changing video camera sensitivity and increasing the amount of electrical power required by the video security monitoring system, and altering an iris of the video camera to compensate for a change in video camera sensitivity and commencing conversion by the digital video image compression subsystem of successive images of the video signal received from the video camera into compressed digital video data to produce compressed digital video data for a sequence of images of the area viewed by the lens of the video camera; and

transmitting the compressed digital video data from the video security monitoring system to a remote video monitoring facility via a communication channel.

29. The method of claim 28 further comprising the steps of:

compressing the video signal to produce a lower quality image while the digital video image compression subsystem detects no motion within a central region of the image; and

compressing the video signal to produce a higher quality image if the digital video image compression subsystem detects motion in the central region of the image.

Description Submit all comments and votes

TECHNICAL FIELD

The present invention relates generally to the technical field of security devices that sense movement, and more particularly, to video systems for observing an area to detect motion.

BACKGROUND ART

Well known in the art are video security systems that present an observer located at a video monitoring facility with a succession of images of different areas, each area being viewed by a lens of a different video camera. However, these video systems are completely passive in the sense that detecting an intrusion into the area viewed by the camera's lens remains the responsibility of the observer. That is, the video camera provides the observer with no assistance in detecting an intrusion. Thus, if the observer at the video monitoring facility is distracted or fails to notice the occurrence of an intrusion, no alarm will be raised. It is also possible that the occurrence of an intrusion might be missed because images of other areas are being presented to the observer at the instant the intrusion occurs. Furthermore, because the video signal from each video camera must be transmitted to the video monitoring facility by a wide bandwidth, coaxial cable, or by some other type of wide bandwidth, dedicated communication channel such as a microwave link, it is commercially impractical to distribute this type of video security system at sites randomly located within an extended geographic area, such as throughout a large city.

In addition to well known, passive security systems of the type described above, active, motion sensing video systems have been developed for military battlefield applications. However, these experimental military systems were physically very large, e.g. were carried on a trailer and towed by a jeep, consumed hundreds of watts of power, and were very expensive.

Recently, throughout the world, telephone systems have begun providing digital communication capability in accordance with the Integrated Services Digital Network ("ISDN") standard established by the International Telegraph and Telephone Consultative Committee ("CCITT"). Under this CCITT standard, a basic ISDN access consists of two full-duplex 64 kilobits per second ("kbps") digital data channels, called channel B1 and channel B2, plus another full-duplex 16-kbps digital channel, called a D channel. Under the CCITT standard, using time division multiplexing, all three of these digital data channels may be transmitted over a single pair of twisted wires, or over two pairs of twisted wires. While ISDN basic access was originally intended to provide voice and slow speed data communication services, over the years developments in digital signal processing and compression techniques have advanced technology to the extent that compressed video data may now be transmitted using an ISDN basic access communication channel. These techniques have progressed to such an extent that there now exist several alternative video data compression techniques such as the CCITT H.261 picture phone standard, the Joint Photographic Experts Group ("JPEG") standard, and the Moving Picture Experts Group ("MPEG") standard that permit transmission of video images over an ISDN basic access communication channel. Furthermore, the CCITT has established a standard H.221 which permits intermixed transmission over an ISDN basic access communication channel of images compressed in accordance with both the H.261 picture phone standard, and images compressed in accordance with the JPEG standard.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a video security monitoring system that may be economically installed at randomly located sites within a large geographic area.

Another object of the present invention is to provide a video security monitoring system that assists an observer at a video monitoring facility in detecting the occurrence of motion in the area viewed by a lens of a video camera.

Another object of the present invention is to provide a video security monitoring system that detects movement in the area viewed by a lens of a video camera even thought an observer at a video monitoring facility is not presently observing an image of the area.

Another object of the present invention is to provide a video security monitoring system that may be installed more easily.

Another object of the present invention is to provide a video security monitoring system that retains an image of an intrusion for an unlimited period of time thereafter, even following an interruption of electrical power to the video security monitoring system.

Another object of the present invention is to provide a video security monitoring system that may surreptitiously illuminate an area while it is being observed.

Another object of the present invention is to provide a video security monitoring system adapted for verifying an individual's authorization to enter the area under observation.

Yet another objection of the present invention is to provide an economically practical motion sensing video security monitoring system.

Briefly, a video security monitoring system in accordance with the present invention includes a video camera for producing a video signal from an image of an area viewed by a lens of the video camera. The video security monitoring system also includes a digital video image compression subsystem that receives the video signal from the video camera. Upon receiving the video signal, the digital video image compression subsystem processes the video signal to determine if any motion is occurring in the area viewed by the camera's lens. If the digital video image compression subsystem detects motion, it notifies a digital signal transmission interface and control that motion has been detected.

The digital signal transmission interface and control, which supervises the overall operation of the video security monitoring system, upon being notified that the digital video image compression subsystem has detected motion activates the digital video image compression subsystem to begin converting the video signal into compressed digital video data. After converting the image of the area being viewed by the video camera's lens into compressed digital video data, the digital video image compression subsystem transmits the compressed data to the digital signal transmission interface and control. The digital signal transmission interface and control in turn transmits the compressed digital video data from the video security monitoring system to a remote video monitoring facility.

In the preferred embodiment of the video security monitoring system of the present invention, the digital signal transmission interface and control transmits the compressed digital video data to the video monitoring facility via an ISDN basic access communication channel. Because telephone systems in the industrialized nations generally provide ISDN basic access communications, the digital signal transmission interface and control need establish a connection for communicating with the video monitoring facility only if the digital video image compression subsystem detects motion in the area viewed by the video camera's lens.

Furthermore, because the ISDN basic access communication channel provides a specified amount of electrical power to a device connected thereto, operation of a video security monitoring system in accordance with the preferred embodiment of the present invention may be energized by electrical power drawn from the ISDN basic access communication channel. During intervals in which motion does not occur, the video security monitoring system operates on only a fraction of the electrical power, i.e., less than one-half watt, provided by the ISDN basic access communication channel. The video security monitoring system operates on such a small amount of power because it is fabricated from Complementary Metal Oxide Silicon ("CMOS") integrated circuits ("ICs") that operate at a reduced clock frequency when notion is not detected. Energizing the video security monitoring system with electrical power drawn from the communication channel significantly simplifies installation of a video security monitoring system since only a single electrical connection must be established.

A video security monitoring system in accordance with the present invention may also include a compressed data memory for temporarily storing compressed digital video data produced by the digital video image compression subsystem. A compressed data memory may be advantageously included in the video security monitoring system of the present invention to temporarily store compressed digital video data during an interval between detection of motion by the digital video image compression subsystem and establishment of an ISDN basic access communication link between the video security monitoring system and the video monitoring facility. If compressed digital video data has been stored in the compressed data memory, responsive to commands transmitted from an observer at the video monitoring facility to the video security monitoring system, the system may provide the observer with images of the area viewed by the camera's lens beginning at the instant at which the digital video image compression subsystem detects motion. Moreover, because the preferred embodiment of the compressed data memory retains compressed digital video data after an interruption of electrical power to the video security monitoring system, images stored in the compressed data memory may be retrieved and viewed long after their occurrence and storage.

The video security monitoring system of the present invention may also include a camera control for effecting changes in various settings of the video camera responsive to control signals received from the digital signal transmission interface and control. For example, the camera control may be adapted for changing the setting of the camera's iris, the focus of the camera's lens, and the lens' zoom if the camera has a zoom lens. Furthermore, the camera control may also be adapted for tilting and panning the video camera to change the area viewed by its lens. Analogously, the video security monitoring system may also include a serial control for exchanging signals between the digital signal transmission interface and control and a monitoring device external to the video security monitoring system. For example, the serial control might exchange signals between the digital signal transmission interface and control and a weather station that monitors atmospheric conditions.

A video security monitoring system in accordance with the present invention may also include a strobe light for illuminating the area viewed by the camera's lens. The area viewed by the lens is preferably illuminated by the strobe light only at the instant the video camera is acquiring an image to be processed by the digital video image compression subsystem. This mode of operating the strobe light reduces the electrical power required by the video security monitoring system. The strobe light is preferably a Light Emitting Diode ("LED") that emits infra red illumination. Because an intruder cannot normally perceive the presence of infra red illumination, if they do not possess an infra red detector they will be unaware that they are being illuminated by the video security monitoring system.

A video security monitoring system in accordance with the present invention may also include a stylus having a source of illumination that may be directed toward the camera's lens. If an individual appropriately positions this stylus while writing an identifying message, for example while writing their name, the video security monitoring system may verify their authorization to enter the area observed by the video security monitoring system. As with the strobe light, the source of illumination included in the stylus is preferable an infra red emitting LED.

A video security monitoring system in accordance with the present invention may also include a microphone for producing an audio signal from sound occurring about the video security monitoring system. If the video security monitoring system includes a microphone, it will also include a digital audio compression-decompression subsystem that receives the audio signal from the microphone. Upon receiving the audio signal, the digital audio compression-decompression subsystem processes the audio signal to determine if any change in sound has occurred about the video security monitoring system. If the digital