Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1998-02-28
2000-05-30
Tong, Nina
Communications: electrical
Condition responsive indicating system
Specific condition
340566, 340683, 73654, 3242072, G08B 2100
Patent
active
060695609
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a detector for detecting vibrations. More particularly the invention pertains to multi-dimensional or seismic vibration detectors.
2. Discussion of Related Art
There is a need in many contexts for a detector for detecting vibrations in, for example, a body to which the detector is fixed. Such a detector is suitable for employment in, for instance, the monitoring of bearings in rotary machines, for activating airbags, in burglar alarms etc. In many practical applications, it is also required that the direction of movement of the detected movement is identified.
For a detector which is used in a security system (burglar alarm), it is of great importance that the detector makes it possible at a very early stage to discover that a break-in is being attempted. It is highly desirable that the security system emits an alarm early, in other words before the break-in attempt has caused any major damage. This early warning system should be combined with an operative facility which ensures that an alarm is signalled only when a real attempted break-in is in progress.
It is previously known in the art to employ, in security systems, detectors which break or make a current circuit when, for example, a door is opened. The drawback in such detectors is that the alarm is made only when the thief has already gained access to the premises and, consequently, the thief has already caused material damage as a result of the break-in itself. The risk is imminent that the thief causes further damage to the interior of the premises when the alarm is sounded and/or when the thief takes goods away in connection with fleeing the scene of the crime.
Movement detectors in premises suffer from corresponding drawbacks since they only indicate a break-in once the thief is inside the premises.
Detectors based on sound analysis suffer from the drawback that the risk of a false alarm is great. In purely practical terms, it has proved that "break-in sound" cannot always be distinguished from "authorised" sound, for example in staircases in apartment buildings.
SUMMARY OF THE INVENTION
The above-outlined needs and wishes are satisfied by means of an apparatus according to the characterising clause of the appended independent claim.
Use of the detector according to the present invention in a security system makes it possible to detect attempts at break-in at a very early stage. The signals obtained from the detector have a very broad frequency spectrum, which makes it possible, for example by means of a signal analyser, to identify a commenced break-in attempt. When the signals from the detector include frequencies indicating vibrations within a predetermined frequency range/amplitudes (break-in indications), reliable detection of the break-in attempt takes place.
It will be obvious to a person skilled in the art that a seismic detector has a large field of application. The above-outlined application in break-in alarms constitutes but a single example of one field of application.
Further expedient embodiments of the present invention are disclosed in the appended subclaims.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described in greater detail hereinbelow, with particular reference to a number of drawings, in which:
FIG. 1 is a cross-section through one embodiment of a magnetic, seismic detector in which electric coils are included;
FIG. 1a is a detailed section of a part of a detector apparatus in the seismic detector according to FIG. 1;
FIG. 1b is a detailed section corresponding to that of FIG. 1a but with an alternative placement of the spring means of the detector apparatus; and
FIG. 1c shows one embodiment of the magnetic, seismic detector in which Hall elements are included;
FIG. 2 is a cross-section through an installed security system comprising an inner part and an outer part;
FIGS. 2a-c show detailed illustrations of the outer part in the region of a fish-eye included in the security system;
FIG. 3 is an electric bl
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Covial Device AB
Tong Nina
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