PURPOSE: To obtain the sensor which hardly cause detection due to carelessness and is inexpensive and easily fitted by breaking the contact of a switch when an arm is pushed by part of the body of an trespasser, and detecting the trespass from variation of a current.
CONSTITUTION: When the trespasser tries to enter through a window, the interval between the arm 7 and window frame is small enough to make part of the human body who passes through the window frame touch it without fail, so the arm 7 is pushed by the part of the body of the trespasser. Consequently, the arm 7 rotates around a shaft 5 as a fulcrum together with an arm holder 4 against the attracting force of a magnet 19 to a magnetic body 18, and the reed switch 15 leaves the magnet 19 by the rotation of the arm 7. Then when the magnetic flux of the magnet 19 does not reach the reed switch 15, the contact of the reed switch is broken, and consequently the current flowing to the reed switch 16 is cut off, so a current monitor circuit detects the trespass of the trepasser from the cutoff of the current.
TANAKA TERUAKI
ITO TOMOHISA
HORIUCHI YASUGO
SECOM CO LTD