The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 05, 1978
Filed:
Jul. 07, 1976
Abstract
A piezoelectric transducer is secured to the surface of a glass sheet to translate mechanical vibrations generated in the glass sheet into an electrical signal when a crack is produced. A detection circuit is connected to the transducer to determine whether the frequency of the signal is above or below a predetermined value. If the frequency is higher than the predetermined value, a warning signal is derived to indicate a crack and therefore probably a burglary. Alternatively, the piezoelectric transducer in the transmit mode is excited electrically by an impulse to introduce an elastic wave into the glass sheet. A gate circuit is connected to the transducer to pass signals resulting from reflection of the elastic wave from discontinuities in the glass sheet which result from a crack. The reflected crack indicating signals are passed through the gate to the transducer when it is in the receive mode.