Container defect detection apparatus

摘要

An apparatus for detecting defects in empty containers, such as dents in cans, is disclosed. The containers are magnetically struck, causing them to ring at their natural frequencies. A microphone senses this resonance; a bandpass filter filters out the known frequencies generated by an acceptable container. The energy associated with other frequencies is examined to detect defects in the containers. A circuit for reducing the effects of background acoustic noise and a circuit for sensing the amount of energy imparted to the container when it is struck are also disclosed.