Ultrasonic sensor

Claim 2

In a sensing device for determining the passage of high velocity, relatively small articles, the combination comprising: ultrasonic transducer means having an ultrasonic transmitting portion and an ultrasonic receiving portion, said transmitting portion radiating ultrasonic energy having a predetermined wavelength which is determined by the velocity of propagation of the ultrasonic signal divided by the frequency between said transmitting portion and said receiving portion, support means for receiving and holding said transmitting portion and said receiving portion and maintaining a spacing therebetween, said spacing being an integral number of half wavelengths of said predetermined wavelength, amplifier means coupled to said receiving portion of said ultrasonic means to produce an output signal corresponding to the signal received from said transmitting portion and output means coupled to said amplifier means to produce a count signal in response to a change in amplitude of said output signal, whereby high velocity, relatively small articles passing between said transmitting and receiving portions will produce a change in amplitude of said output signal to correspond to said count signal.

Claim 3

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 1 wherein said support means is a guide chute adapted to receive seeds therethrough as they are being planted, saiD output means being coupled to a count readout device which provides a readout as to the number of seeds that have been planted.

Claim 4

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 2 wherein said transmitting and receiving portions are separate and discrete elements spaced apart from one another and which have their respective radiating and receiving surfaces facing one another.

Claim 5

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 3 wherein said discrete spaced apart elements are mass-loaded piezoelectric ceramic elements.

Claim 6

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 1 wherein said change in amplitude of said output signal is a decrease in amplitude.

Claim 7

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 1 wherein said amplifier means is formed by a pair of direct current coupled transistors.

Claim 8

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 6 wherein said direct current coupled transistors have their collector electrodes tied together and the emitter electrode of one transistor directly connected to the base electrode of the other transistor.

Claim 9

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 1 further including drive amplifier means coupled to said transmitting portion of said ultrasonic transducer means, said amplifier means having the output thereof coupled to the input of said drive amplifier to provide a closed loop oscillator circuit including said transmitting portion, said receiving portion, said amplifier means and said driver amplifier.

Claim 10

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 1 wherein said output means is a transistor having base, emitter and collector electrodes, said base electrode coupled to said amplifier means to receive said output signal and bias the base emitter junction of said transistor to render the transistor conductive, said change in amplitude of said output signal rendering said transistor nonconductive to produce said count signal.

Claim 11

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 9 wherein said transistor is coupled to said output means through a capacitor.

Claim 12

In a sensing device for determining the passage of high velocity, relatively small articles the combination comprising: a first ultrasonic transducer means for transmitting ultrasonic wave energy therefrom, a drive circuit coupled to said first ultrasonic transducer means for driving the same at a predetermined output frequency, second ultrasonic transducer means spaced from said first ultrasonic transducer means for receiving output signals therefrom over an air gap therebetween, a receiving circuit coupled to said second ultrasonic transducer means for receiving and amplifying the ultrasonic signals sensed thereby, a circuit point connected to the output of said receiving circuit, said circuit point having an amplified signal applied thereto from said receiving circuit, coupling circuit means between said output circuit point and the input of said driver circuit to provide a feedback path thereto, said output circuit point also being coupled to readout means, said first ultrasonic transducer element, said driver circuit, said second ultrasonic transducer element, said receiver circuit, said coupling circuit means and said gap forming a closed loop oscillator circuit operating at said predetermined frequency.

Claim 13

In a sensing device for determining the passage of high velocity, relatively small articles the combination comprising: a first ultrasonic transducer means for transmitting ultrasonic wave energy therefrom, a drive circuit coupled to said first ultrasonic transducer means for driving the same at a predetermined output frequency, second ultrasonic transducer means spaced from said first ultrasonic transducer means for receiving output signals therefrom over an air gap therebetween, a receiving circuit coupled to said second ultrasonic transducer means for receiving and amplifying the ultrasonic signals sensed thereby, a circuit point connected to the output of said receiving circuit, said circuit point having an amplified signal applied thereto from said receiving circuit, coupling circuit means between said output circuit point and the input of said driver circuit to provide a feedback path thereto, said output circuit point also being coupled to readout means, said first ultrasonic transducer element, said driver circuit, said second ultrasonic transducer element, said receiver circuit, said coupling circuit means and said gap forming a closed loop oscillator circuit operating at said predetermined frequency.

Claim 14

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 11 wherein said driver circuit is a push-pull amplifier circuit, and wherein said recEiver circuit is formed by a pair of direct current coupled transistors having their collector electrodes tied together and the emitter electrode of one transistor direct current coupled to the base electrode of the other transistor.

Claim 15

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 12 wherein said first and second ultrasonic transducer means are mass-loaded piezoelectric ceramic elements.

Claim 16

In the sensing device for determining the passage of high velocity, relatively small articles as set forth in claim 11 wherein the dimension of said gap between said first and second ultrasonic transducer elements is an integral number of half wavelengths of said predetermined frequency.