Patent ID: 7453390

Claim:
A detection device for detecting a body entering a predetermined range, comprising: a transmission means for periodically radiating a pulse-like transmission signal in a form of an electromagnetic wave to which a band restriction has been applied, the pulse-like transmission signal generated from determining a main frequency wave and creating additional waves of different frequencies based on the main frequency wave and combining the additional waves with the main frequency wave; a first reception means and a second reception means, each of which perform: receiving, as a reception signal, the electromagnetic wave reflected by the body, sampling of the reception signal after a predetermined delay time has elapsed from transmission, the first reception means sampling at the end of a first delay time and the second reception means sampling at the end of a second delay time, and judging, based on the sampling, whether the body is present; and a judgment means for: judging, based on judgment results of each of the first reception means and the second reception means, whether the body has entered into the predetermined range, and outputting a judgment result, wherein the second delay time is set to be an offset of the first delay time by a length of time equivalent to a half-period of the main frequency wave of the transmission signal.