Ultrasound-signal radiating device
First Claim
1. An ultrasound-signal radiating device comprising:
- a piezoelectric substrate having two end surfaces;
a first input interdigital transducer;
a second input interdigital transducer;
an output interdigital transducer, all said first input-, said second input-, and said output interdigital transducers being formed on one end surface of said piezoelectric substrate;
a cap mounted on a surface part of the other end surface of said piezoelectric substrate, said surface part corresponding to a surface part, including said first input- and said output interdigital transducers, of said one end surface of said piezoelectric substrate;
an amplifier; and
a modulator with an input terminal, said first input interdigital transducer receiving an input electric signal, exciting a non-leaky elastic wave in said piezoelectric substrate, said output interdigital transducer detecting said non-leaky elastic wave as a delayed electric signal, said amplifier amplifying said delayed electric signal and feeding a signal part, as said input electric signal, of an amplified electric signal, back to said first input interdigital transducer, again, said modulator receiving not only an input message-signal through said input terminal but also a remaining signal part, as a carrier signal, of said amplified electric signal, modulating an amplitude of said carrier signal according to said input message-signal, and generating an AM signal, said second input interdigital transducer receiving said AM signal, exciting a leaky elastic wave in said piezoelectric substrate, and radiating said leaky elastic wave in the form of a longitudinal wave into a liquid through a remaining surface part of said other end surface of said piezoelectric substrate.
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Abstract
An ultrasound-signal radiating device comprises a piezoelectric substrate, a first input interdigital transducer, a second input interdigital transducer, an output interdigital transducer, a cap, an amplifier, and a modulator with an input terminal. All the interdigital transducers are formed on one end surface of the piezoelectric substrate. The cap is mounted on a surface part of the other end surface of the piezoelectric substrate. If an input electric signal is applied to the first input interdigital transducer, a non-leaky elastic wave is excited in the piezoelectric substrate owing to the existence of the cap. The non-leaky elastic wave is detected at the output interdigital transducer as a delayed electric signal, which is amplified via the amplifier. A signal part of an amplified electric signal is fed back to the first input interdigital transducer, again. A remaining signal part, as a carrier signal, of the amplified electric signal is transmitted to the modulator, where an amplitude of the carrier signal is modulated according to an input message-signal applied from the input terminal. Thus, an AM signal is generated, and then, applied to the second input interdigital transducer. In this time, a leaky elastic wave is excited in the piezoelectric substrate, and radiated effectively in the form of a longitudinal wave into a liquid kept in contact with a remaining surface part of the other end surface of the piezoelectric substrate.
10 Citations
9 Claims
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1. An ultrasound-signal radiating device comprising:
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a piezoelectric substrate having two end surfaces;
a first input interdigital transducer;
a second input interdigital transducer;
an output interdigital transducer, all said first input-, said second input-, and said output interdigital transducers being formed on one end surface of said piezoelectric substrate;
a cap mounted on a surface part of the other end surface of said piezoelectric substrate, said surface part corresponding to a surface part, including said first input- and said output interdigital transducers, of said one end surface of said piezoelectric substrate;
an amplifier; and
a modulator with an input terminal, said first input interdigital transducer receiving an input electric signal, exciting a non-leaky elastic wave in said piezoelectric substrate, said output interdigital transducer detecting said non-leaky elastic wave as a delayed electric signal, said amplifier amplifying said delayed electric signal and feeding a signal part, as said input electric signal, of an amplified electric signal, back to said first input interdigital transducer, again, said modulator receiving not only an input message-signal through said input terminal but also a remaining signal part, as a carrier signal, of said amplified electric signal, modulating an amplitude of said carrier signal according to said input message-signal, and generating an AM signal, said second input interdigital transducer receiving said AM signal, exciting a leaky elastic wave in said piezoelectric substrate, and radiating said leaky elastic wave in the form of a longitudinal wave into a liquid through a remaining surface part of said other end surface of said piezoelectric substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
another output interdigital transducer, formed on said one end surface of said piezoelectric substrate and detecting a reflected longitudinal wave at a material in said liquid as a delayed output signal through said remaining surface part of said other end surface of said piezoelectric substrate; and
a demodulator with an output terminal, said demodulator receiving said delayed output signal, demodulating an amplitude of said delayed output signal, and delivering an output message-signal through said output terminal.
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6. An ultrasound-signal radiating device as defined in claim 1 further comprising:
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another piezoelectric substrate having two end surfaces;
another output interdigital transducer, formed on one end surface of said another piezoelectric substrate and detecting a reflected longitudinal wave at a material in said liquid as a delayed output signal through the other end surface of said another piezoelectric substrate; and
a demodulator with an output terminal, said demodulator receiving said delayed output signal, demodulating an amplitude of said delayed output signal, and delivering an output message-signal through said output terminal.
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7. An ultrasound-signal radiating device as defined in claim 1, wherein said piezoelectric substrate is made of a piezoelectric ceramic thin plate, the polarization axis thereof being parallel to the thickness direction thereof.
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8. An ultrasound-signal radiating device as defined in claim 1, wherein said piezoelectric substrate is made of a piezoelectric polymer thin plate.
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9. An ultrasound-signal radiating device as defined in claim 1, wherein the electrode-finger direction of said first input interdigital transducer is orthogonal to that of said second input interdigital transducer.
Specification