Electronic missing file locator system

Claim 1

Apparatus for attachment within a file folder having a large mass of sound absorbing material and having a space along an edge portion thereof, without appreciably increasing the thickness of said file folder, said apparatus being responsive to an outside stimulus from a remotely located interrogator so as to aid in locating the file folder if misplaced, said apparatus comprising: a thin sheet of material conforming substantially to the inside dimensions of one flap of a file folder; a loop antenna secured to said thin sheet proximate the outer circumference thereof, said antenna having opposite ends; a battery in wafer form secured to said thin sheet having power output terminals for providing a D.C. operating voltage; receiver circuitry secured to said thin sheet of material having two signal input terminals connected to said opposite ends of said antenna, two power input terminals connected to said power output terminals of said battery, and signal output terminals; a sound producing device secured to said sheet and coupled to said output terminals; said receiver circuitry having signal storage means for storing an address for said file folder and means for activating said sound producing device in response to a signal at its input terminals that represents said address; the thickness of any one of said receiver circuitry, battery and sound producing device not exceeding 0.15 of an inch; and said apparatus being attached to said file folder for positioning said sound producing device adjacent said space, and said space providing a low acoustic impedance pathway from said sound producing device to areas outside said file folder.