This invention relates generally to alarm systems. More specifically, this invention relates to alarm systems employing a single transmission line carrying signals from both sensing elements and monitoring devices.
Conventional alarm systems, such as passive infrared (PIR) intrusion detectors, see extensive use for detecting and deterring intrusions such as break-ins or trespasses. One such alarm system is shown in block diagram form in
While often effective in detecting and monitoring intrusions, conventional alarm systems 10 suffer from certain drawbacks. Often, the sensing element 20 and camera 50 are located at or near the area to be monitored, while the alarm indicator 30 and monitor 60 are placed at a remote area. Accordingly, alarm systems such as alarm system 10 require two transmission lines, i.e. wires 40 and coaxial cable 70, to be extended between these areas. The use of two such cables instead of one consumes extra space and adds cost. Also, as these two areas can be far apart, additional effort and expense are required to install two lines instead of one. In addition, where a sensing element 20 with the associated alarm indicator 30 is already installed, retrofitting such a site would be expensive.
In the prior art, it is also known to use a plurality of cameras connected via a single co-axial cable to a plurality of monitors. Thus the cameras share their signals on the single co-axial cable. However, none of the cameras share their signals with the output of a sensing element which does not output a video frequency signal.
Accordingly, it is desirable to provide an alarm system that employs a single transmission line capable of carrying signals from both sensing element 20 and monitoring devices such as camera 70. The use of a single transmission line eliminates the need for a second line, reducing overall system cost and effort in installation, and permits greater number of existing alarm sensors 20 to be retrofitted with cameras 70 to reduce false alarms.
The invention can be implemented in numerous ways, including as a method, system, and device. Various embodiments of the invention are discussed below.
In the present invention an intrusion detection system comprises a detection element configured to detect an intrusion in a location, and to transmit an intrusion signal upon detection of the intrusion. The system further comprises a monitoring device configured to capture images of the location upon the detection of the intrusion, and to transmit image signals representing the captured images. Finally the system comprises a transmission line in electrical communication with the detection element and the monitoring device, the transmission line configured to carry the intrusion signals and the image signals.
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention
For a better understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:
Like reference numerals refer to corresponding parts throughout the drawings.
In one sense, the invention relates to an improved alarm system that utilizes a single transmission line instead of the dual transmission lines often required in conventional alarm systems. Alarm systems often have sensing elements that detect intrusions, and monitoring devices such as cameras for confirming the alarm detection by capturing a visual record of the intrusion. Instead of employing separate transmission lines for each element or device, a combiner circuit transmits signals from the sensing elements and the monitoring devices on the same transmission line. At the other end of this transmission line, a separator circuit receives these signals and, upon detecting a signal from the sensing elements, transmits an alarm signal to the components of the alarm system that initiate an alarm. The separator circuit also routes the camera signals to those components of the alarm system that record/display images from the camera.
By combining signals from the sensing elements and camera, then separating the signals downstream and sending them to their appropriate destinations, the combiner and separator circuits allow for a conventional single transmission line, such as a single cable comprising of four wires (two to carry signal, and two to carry power), to be used. In contrast to the dual transmission lines required by many conventional systems, the use of a single transmission line allows for more inexpensive alarm systems that are also easier and quicker to install. Finally, the cost of retrofitting an existing alarm sensor with an additional camera is greatly reduced.
In order to carry signals from both a sensing element 110 and camera 120 on the same line, transmission line 150 includes a combiner circuit 160 for combining signals from both these elements onto the same line, as well a separator circuit 170 for directing different components of the combined signal to different destinations. In operation then, the combiner circuit 160 combines signals from the sensing element 110 and camera 120 onto the same transmission line 150. These combined signals travel downstream along the transmission line 150 to the separator circuit 170, which directs the video or image signals to the monitor 140, and transmits alarm signals to the alarm indicator 130. In this manner, different signals from different sources of an alarm system (i.e., sensing element 110 and camera 120) are combined onto a single transmission line 150, where they are later separated and routed to different destinations (i.e., the alarm indicator 130 and monitor 140). Such a configuration allows this single transmission line to take the place of the dual transmission lines 40, 70 of
In addition, one of skill will realize that the invention does not limit itself to the use of these specific components, but rather employs them as an example of the more general concept of combining separate signals from any sensing elements and any monitoring devices onto any single transmission line. Accordingly, the sensing element 110 and camera 120 can be any devices used in alarm systems to detect and monitor intrusions. For instance, the sensing element 110 can be a passive infrared (PIR) detector capable of detecting infrared radiation given off by potential intruders. However, the sensing element 110 can also be a microwave detector, a photo beam detector, a glass break sensor, a door contact sensor, or any other sensing element capable of being employed to detect an intrusion. Likewise, the camera 120 is commonly a video camera for capturing video images of intruders, but it can also be any device for monitoring the location of a potential intrusion, such as a still-frame camera or any other audio/video recording device. In addition, the combiner circuit of
The combined signals are transmitted along the transmission line 220 (i.e., the transmission line 150 of
While the intrusion detection signal acts to generate a signal that toggles the switch 350, the image signals are amplified by amplifier 360 (similar to the amplifier 200 of
As previously mentioned, the sensing element 110 and camera 120 are often co-located. As a result, some embodiments of the invention integrate both these components within a single housing. This single housing produces alarm systems that are particularly easy to install and use, as such alarm systems include both a single transmission line and a single housing.
As shown in
In embodiments employing a lens such as a fresnel lens, light paths to/from the sensing element 110 are modified so as to provide a field of view that facilitates the ability of the sensing element 110 to detect intrusion. More specifically, the lens 450 allows the sensing element 110 to better detect intrusion across a field of view.
One of skill will observe that the invention is not limited to embodiments employing housings, but rather merely discloses sensing elements and monitoring devices. Similarly, housings of the invention are not limited to single-housing configuration, nor to the configuration shown in
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. For example, alarm systems constructed according to the invention can employ any type and number of sensing element and any type of monitoring device. Similarly, the signals from these sensing elements and devices can be combined for transmission on any type of transmission line. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated