PURPOSE: To constitute the titled apparatus so that no alarm is generated when an operator is present in a detection area but an invasion alarm is generated after a predetermined time was elapsed from the point of time when said operator gets out of said area.
CONSTITUTION: When an operator closes a switch SWon to start a moving body detection circuit part 1, to which ultrasonic Doppler effect is applied, and digital output corresponding to the detection output from the terminal (a) of the circuit part 1 is generated on the basis of said detection output from the window comparator 31 of a delay circuit part 4. The H-output from the monomultivibrator 33 triggered through the delay circuit 32 is applied to a clock terminal CK and the L-output of the comparator 31 is applied to a D-terminal D to bring the Q-output of D-type FF to L and an AND gate 35 is closed. By this system, no alarm based on the detection output is generated as far as the operator is present in a detection area. When the operator gets out of the detection area, the output of FF34 is reversed to H after the elapse of time corresponding to time constant by the resistance Rt and capacity Ct of the circuit 4 and an invasion alarm is generated.
INOUE HIRONOBU
SAKURAI YOSHIHIRO
YONEZAWA YASUNORI
