Glass breakage detector
First Claim
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1. A method of detecting breaking glass comprising:
- detecting by said transducer means structurally-transmitted vibrations of impact on glass for generating a first signal;
gating a circuit in said transducer means responsive to said first signal to enable detection by said transducer means of airborne-transmitted sounds;
detecting by said transducer means airborne-transmitted sounds emitted by breaking glass for generating a second signal; and
combining said first and second signals in accordance with a time-dependent function to generate an alarm signal indicative of breaking glass.
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Abstract
A glass breakage detector utilizes a single microphone or piezoelectric element as a transducer to detect both the structurally-transmitted vibrations and airborne sounds indicative of breaking glass. The structurally transmitted component and airborne component are combined in accordance with a time-dependent function to provide an indication of breaking glass which has a low false alarm rate.
31 Citations
23 Claims
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1. A method of detecting breaking glass comprising:
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detecting by said transducer means structurally-transmitted vibrations of impact on glass for generating a first signal; gating a circuit in said transducer means responsive to said first signal to enable detection by said transducer means of airborne-transmitted sounds; detecting by said transducer means airborne-transmitted sounds emitted by breaking glass for generating a second signal; and combining said first and second signals in accordance with a time-dependent function to generate an alarm signal indicative of breaking glass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for detecting breaking glass comprising:
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transducer means for detecting structurally=transmitted vibrations of impact on glass and airborne-transmitted sounds emitted by breaking glass and having an output signal; circuit means coupled to said transducer means for generating a first signal in response to said structurally-transmitted vibrations, said first signal gating a filter circuit for receiving said airborne-transmitted sounds and for combining in accordance with a time-dependent function information in said output signal indicative of said structurally-transmitted vibrations with information in said output signal indicative of said airborne-transmitted sounds for generating an alarm signal indicative of breaking glass. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification