Motion detecting apparatus and intruder alarm

Claim 2

A motion-detecting device comprising a source of ultrasonic radiation having a frequency above 20 kilocycles, a transducer adapted to generate an electrical signal responsive to the ultrasonic radiation from said source, an amplitude detector having an input electrically connected to the transducer and an output for conducting the audiofrequency component of the electrical signals generated by the transducer to the output of said detector and isolating the output from the ultrasonic frequency component of the electrical signals generated by the transducer, and means connected to the output of said detector for producing an electrical output responsive to audio signals having a repetition rate greater than a threshold value, said means preventing production of said electrical output responsive to audio signals having a frequency lower than the threshold value, said means including an electronic switch having an input circuit, said electronic switch being operable by a predetermined actuation potential across said input circuit, a filter including a capacitor connected across said input circuit, and means For converting said audio signals from said detector into direct current pulses supplied to said capacitor and said input circuit, a plurality of said pulses being effective to charge said capacitor to build up a potential across said input circuit exceeding said actuation potential so as to operate said electronic switch in response to pulses having a frequency greater than said threshold value, said input circuit of said electronic switch including a low impedance element across said capacitor to discharge said capacitor and thereby limit the potential across said input circuit to a value less than said actuation potential for pulses having a frequency less than said threshold value.

Claim 3

A motion-detecting device for use in an enclosure comprising the combination of claim 1 wherein said filter and said input circuit are constructed and arranged to establish said threshold frequency at substantially one-thousandth of the frequency of the ultrasonic source of radiation.

Claim 4

A motion-detecting device for use in an enclosure comprising the combination of claim 1 wherein the frequency of the ultrasonic source is of the order of 40 kilocycles per second, and the threshold frequency is of the order of 40 cycles per second.

Claim 5

A motion-detecting device for use in an enclosure comprising the combination of claim 1 wherein the electronic switch comprises a bistable flip-flop.

Claim 6

A motion detector comprising the combination of claim 1 in combination with a second capacitor connected to said first mentioned capacitor to supply the direct current pulses thereto, said second capacitor being larger than the first capacitor.

Claim 7

A motion-detecting device comprising the combination of claim 1 wherein the source of ultrasonic radiation comprises an oscillator having a transistor with a base, a collector and an emitter, a source of direct current potential connected between the collector and the emitter, and a transducer having a pair of piezoelectric elements adapted to oscillate at the same frequency in the ultrasonic range, said transducer including tow electrodes abutting each piezoelectric element, one of the electrodes abutting each element being electrically interconnected and connected to one terminal of the power source, one of the other electrodes being electrically connected to the collector of the transistor and the other of the other electrodes being electrically connected to the base of the transistor.

Claim 8

A motion detector comprising a source of ultrasonic radiation having a frequency above 20 kilocycles, a transducer adapted to generate an electrical signal responsive to the ultrasonic radiation from said source, an amplitude detector having an input electrically connected to the transducer and an output, first electrically operable switching means, and a filter electrically connected between the first switching means and the output of the amplitude detector for isolating low frequencies from the first switching means and preventing actuation thereof responsive to said low frequencies, in combination with an alarm circuit, an electrical delay means electrically connected between the first switching means and said alarm circuit, and means electrically coupled to the first switching means to prevent actuation thereof including a pair of single-pole double-throw true deactuation switches and a plurality of identical single-pole double-throw false deactuation switches mounted adjacent to each other, each of these switches having a pole contact normally butting one stationary contact and said one stationary contact of each switch being connected to one terminal of a power source, the other stationary contact of each switch being connected to the other terminal of the power source, a bistable flip-flop having a first stage with a first input and a second stage with a second input, the first and second stages having first and second output circuits, respectively, and one of said output circuits being at a higher potential than the other, the pole contact of one of the true deactuation switches being connected to the first input of the flip-flop, the potential of the power source on the second stationary contact being adapted to flip the flip-flop and the second stage being normally conducting, the pole contact of each of the false deactuation switches being electrically connected to the second input terminal of the flip-flop, a coincidence circuit having a resistor and three diodes connected in a common junction, the other terminal of the resistor being connected to the other terminal of the power source, the other terminal of one of the diodes being connected to the output circuit of the second stage of the flip-flop, the other terminal of another diode being electrically connected to the pole contact of the other true deactuation switch, and second electrically operable switching means having an actuation terminal and a pair of switch terminals electrically connected to the first electrically operable switching means to prevent closing of said second switching means, the other terminal of the third diode being electrically connected to the input terminal of the second switching means to actuate said second switching means responsive to the coincidence of back bias on the first and second diodes of said coincidence circuit.

Claim 9

A motion detector comprising a source of ultrasonic radiation having a frequency above 20 kilocycles, a transducer adapted to generate an electrical signal responsive to the ultrasonic radiation from said source, an amplitude detector having an input electrically connected to the transducer and an output, first electrically operable switching means, and a filter electrically connected between the first switching means and the output of the amplitude detector for isolating low frequencies from the first switching means and preventing actuation thereof responsive to said low frequencies, in combination with an alarm circuit, an electrical delay means electrically connected between the first switching means and said alarm circuit, and means electrically coupled to the first switching means to prevent actuation thereof including a pair of single-pole double-throw true deactuation switches and a plurality of identical single-pole double-throw false deactuation switches mounted adjacent to each other, each of these switches having a pole contact normally butting one stationary contact and said one stationary contact of each switch being connected to one terminal of a power source, the other stationary contact of each switch being connected to the other terminal of the power source, a bistable flip-flop having a first stage with a first input and a second stage with a second input, the first and second stages having first and second output circuits, respectively, and one of said output circuits being at a higher potential than the other, the pole contact of one of the true deactuation switches being connected to the first input of the flip-flop, the potential of the power source on the second stationary contact being adapted to flip the flip-flop and the second stage being normally conducting, the pole contact of each of the false deactuation switches being electrically connected to the second input terminal of the flip-flop, a coincidence circuit having a resistor and three diodes connected in a common junction, the other terminal of the resistor being connected to the other terminal of the power source, the other terminal of one of the diodes being connected to the output circuit of the second stage of the flip-flop, the other terminal of another diode being electrically connected to the pole contact of the other true deactuation switch, and second electrically operable switching means having an actuation terminal and a pair of switch terminals electrically connected to the first electrically operable switching means to prevent closing of said second switching means, the other terminal of the third diode being electrically connected to the input terminal of the second switching means to actuate said second switching means responsive to the coincidence of back bias on the first and second diodes of said coincidence circuit.

Claim 10

A motion detector comprising the combination of claim 7 in combination with third electrically operable switching means having an input terminal and an output terminal connected to said alarm circuit, the input terminal of the third switching means being electrically coupled to the pole contacts of all of the false deactuation switches.