ApplicationNo. 05/767941 filed on 02/11/1977
US Classes:340/566, Vibration310/319, Electrical output circuit310/323.21, Detector (e.g., sensor)310/366More than two
ExaminersPrimary: Swann, III, Glen R.
Attorney, Agent or Firm
Foreign Application Priority Data1976-09-09 CH
AbstractDamage to a frangible article, particularly a glass window is detected by sensors responsive to oscillations in different frequency bands. Only when all the sensors are simultaneously responsive is an alarm signal, denotive of damage to the article, developed. Piezo-ceramic transducers respond to frequencies within the range of 30 kHz to 1 MHz. The sensors are connected in parallel with inductors to provide resonant amplification of the voltage developed. The resultant signals are amplified and applied to an AND gate yielding the required output signal.