Security system
First Claim
1. A system for sensing activity affecting a secured area or a boundary which defines that secured area, said system comprising:
- a transducer including a ferroelectric film of polyvinylidene fluoride (PVDF) with first and second opposed major surfaces having, respectively, first and second electrodes deposited thereon;
said transducer being disposed with its first major surface in acoustic and thermal contact with a portion of said boundary to transduce individual types of thermal and mechanical activity affecting said boundary into electrical signals, each activity of interest being transduced into an electrical signal having a corresponding waveform;
means responsive to the presence of said electrical signals corresponding to said individual activities of interest for separately recognizing the waveforms which correspond to each of at least two different ones of said activities for detecting the occurrence of those at least two different individual activities and for producing an output signal identifying each of said individual activities whose occurrence is detected; and
means responsive to said identification signal for generating an alarm signal in response to the identification of specific activities.
1 Assignment
0 Petitions
Accused Products
Abstract
A security system is disclosed which senses a variety of activities which affect a secured area and/or the boundary which defines it and identifies particular activities rather than merely indicating that some activity is present. A transducer comprising an electroded ferroelectric film of polyvinylidene fluoride (PVDF) serves as a transducer which provides different output signals in response to different stimuli and responds simultaneously to thermal and mechanical activity. A signal processor separately recognizes the signals produced in response to different activities and identifies the activities detected. An alarm processor controls the system and generates alarm signals in response to the detection of specific activities.
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Citations
10 Claims
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1. A system for sensing activity affecting a secured area or a boundary which defines that secured area, said system comprising:
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a transducer including a ferroelectric film of polyvinylidene fluoride (PVDF) with first and second opposed major surfaces having, respectively, first and second electrodes deposited thereon; said transducer being disposed with its first major surface in acoustic and thermal contact with a portion of said boundary to transduce individual types of thermal and mechanical activity affecting said boundary into electrical signals, each activity of interest being transduced into an electrical signal having a corresponding waveform; means responsive to the presence of said electrical signals corresponding to said individual activities of interest for separately recognizing the waveforms which correspond to each of at least two different ones of said activities for detecting the occurrence of those at least two different individual activities and for producing an output signal identifying each of said individual activities whose occurrence is detected; and means responsive to said identification signal for generating an alarm signal in response to the identification of specific activities. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification