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:
Aug. 18, 1998
Filed:
Mar. 07, 1997
Hirotugu Ishino, Toyohashi, JP;
Akira Kurahashi, Nukata-gun, JP;
Denso Corporation, Kariya, JP;
Abstract
To improve accuracy in detection of glass breakage, a microphone converts a glass breaking sound into an electrical signal, and high-pass filters and extract high frequency components of 2 kHz or higher and 150 Hz or higher, respectively, from the signal. A half-wave rectifier circuit half-wave rectifies these signals and an amplifier amplifies them. The output of the amplifier is smoothed by smoothing circuits. When the output of the smoothing circuit reaches a predetermined value, a trigger circuit outputs a start pulse to a start terminal of a CPU. Started by the start pulse, the CPU inputs the outputs of the smoothing circuits, converts them into digital values using an A/D converter, determines integrals over 30 ms, and stores the integrals into a RAM. Then, the CPU calculates a ratio of the integral of the output of the smoothing circuit to the integral of the output of the smoothing circuit based on a program stored in a ROM. If the ratio is within a predetermined range, the CPU determines that the detected acoustic waves are the first waves of a glass breaking sound and outputs a glass breakage detection signal.