초록 ▼

An electrical or supersonic wave having a predetermined frequency is emitted as a monitor wave from an emitting device into a zone to be monitored. When a moving object having an inherent velocity range intrudes into the zone, a reflected wave of the monitor wave from the moving object is received b

An electrical or supersonic wave having a predetermined frequency is emitted as a monitor wave from an emitting device into a zone to be monitored. When a moving object having an inherent velocity range intrudes into the zone, a reflected wave of the monitor wave from the moving object is received by a receiver and an alarm signal is issued when the frequency deviation of the reflected wave relative to the frequency of the emitted monitor wave is within the frequency range corresponding to the velocity range. The alarm device has a circuit for producing a first alarm responsive to the alarm signal, a circuit for changing the frequency of the monitor wave when the first alarm is issued, and a circuit for producing a second alarm when a further alarm signal is obtained from the monitor wave with changed frequency within a predetermined time after change of the monitor wave frequency. The circuit for changing the frequency of the monitor wave comprises a variable capacitance diode and a voltage regulating circuit which progressively changes the reverse bias voltage for the variable capacitance diode. The circuit for producing the second alarm comprises a signal processing circuit that produces a trigger signal for producing the most important alarm when an alarm signal has been produced for the overall frequency relative to the monitor wave with progressively changing frequency. The alarm is designed for inclusion of different degrees of seriousness of warning by gradual reduction of the monitor zone with changes in the frequency of the monitor wave.

대표청구항 ▼

An alarm device comprising: a monitor wave emitting device for selectively emitting electrical or supersonic monitor waves of at least two predetermined frequencies, said monitor wave emitting device comprising an oscillating circuit having a resonator including variable capacitance diode means for

An alarm device comprising: a monitor wave emitting device for selectively emitting electrical or supersonic monitor waves of at least two predetermined frequencies, said monitor wave emitting device comprising an oscillating circuit having a resonator including variable capacitance diode means for changing the frequency of the monitor wave to be emitted from a first frequency to a second frequency, reverse bias voltage means coupled to said diode means, and means for emitting the output of said oscillating circuit as monitor waves into the monitored area; a receiver for receiving the reflected waves from a moving object intruding into the monitored area within a given moving velocity range, said receiver comprising receiving means for receiving said reflected waves, said receiving means being more matched to said first frequency monitor wave than to said second frequency monitor wave; a detecting circuit coupled to said receiver for detecting the frequency deviation of the received reflected waves for obtaining a Doppler signal; signal processing circuit means coupled to said detecting circuit for storing, for a predetermined time, signal components of the Doppler signal of the frequency range corresponding to the velocity range when said Doppler signal components have greater than a predetermined amplitude and for generating first and second pulse outputs when the amplitudes of the stored Doppler signal components exceed a predetermined value; first alarm means coupled to said signal processing circuit and activated by said pulse output thereof; a voltage regulating circuit coupled to said signal processing circuit and to said emitting device for receiving the first pulse output for changing the reverse bias voltage to the variable capacitance diode means for a predetermined time in order to change the emitted monitor wave frequency; an alarm signal issuing circuit coupled to said signal processing circuit for generating an output signal when the second pulse output resulting from the reflected monitor wave with the frequency subsequent to the frequency change is generated within a predetermined time following the first pulse output resulting from the reflected monitor wave with the frequency prior to the change; and second alarm means coupled to said alarm signal issuing circuit for generating an alarm responsive to the output signal of said alarm signal issuing circuit.