US 6,640,631 B1Granted

System and measuring sound velocity in material

OwnerKohji Todainventor

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Abstract

A system for measuring sound velocity in material comprises a piezoelectric substrate, first- and second comb-shaped electrodes, and a counter electrode in contact with a surface-part of a material. When input electric signals Ei having carrier frequencies fi, respectively, are applied between the first comb-shaped electrode and the counter electrode in turn, longitudinal waves are radiated into the material. The longitudinal waves are reflected at the opposite surface-part of the material, and then, detected between the second comb-shaped electrode and the counter electrode as delayed electric signals Di, respectively. The input electric signals Ei and the delayed electric signals Di interfere respectively, so that respective interference signals Ri occur. A sound velocity V in the material is estimated from the interference signals Ri.

Claims21

Dependent claims

A system for measuring sound velocity in material comprising:

a piezoelectric substrate;
a first comb-shaped electrode formed on an upper end surface of said piezoelectric substrate;
a second comb-shaped electrode formed on said upper end surface of said piezoelectric substrate;
a counter electrode formed on a lower end surface of said piezoelectric substrate and in contact with a surface-part of a material;
a frequency-sweep oscillator generating input electric signals Ei (i=1, 2, . . . , n) with carrier frequencies fi (i=1, 2, . . . , n), respectively;
and
a frequency analyzer,
said first- and second comb-shaped electrodes forming an interdigital arrangement,
said first comb-shaped electrode and said counter electrode receiving said input electric signals Ei in turn, radiating longitudinal waves into said material along the direction vertical to said lower end surface of said piezoelectric substrate, and making the opposite surface-part of said material reflect said longitudinal waves back,
said second comb-shaped electrode and said counter electrode detecting electrical coupled-signals Ci (i=1, 2, . . . , n) from said input electric signals Ei, respectively, as well as reflected longitudinal waves as delayed electric signals Di (i=1, 2, . . . , n), respectively,
said frequency analyzer causing said electrical coupled-signals Ci and said delayed electric signals Di to interfere respectively, making respective interference signals Ri (i=1, 2, . . . , n), detecting respective amplitudes of said interference signals Ri, clarifying a frequency periodicity Δf from a dependence of said amplitudes on said carrier frequencies fi, and calculating a sound velocity V in said material from the product of said frequency periodicity Δf and twice a distance Z between said piezoelectric substrate and said opposite surface-part of said material.

8 more elements

A system for measuring sound velocity in material comprising:

a first piezoelectric substrate;
a first interdigital arrangement of two comb-shaped electrodes formed on a lower end surface of said first piezoelectric substrate, a lower end surface of said first interdigital arrangement being in contact with a surface-part of a material;
a second piezoelectric substrate;
a second interdigital arrangement of two comb-shaped electrodes formed on an upper end surface of said second piezoelectric substrate;
a counter electrode cemented between said first- and second piezoelectric substrates;
a frequency-sweep oscillator generating input electric signals Ei (i=1, 2, . . . , n) with carrier frequencies fi (i=1, 2, . . . , n), respectively;
and a frequency analyzer,
one of said two comb-shaped electrodes in said first interdigital arrangement and said counter electrode receiving said input electric signals Ei in turn, radiating longitudinal waves into said material along the direction vertical to said lower end surface of said first piezoelectric substrate, and making the opposite surface-part of said material reflect said longitudinal waves back,
one of said two comb-shaped electrodes in said second interdigital arrangement and said counter electrode detecting electrical coupled-signals Ci (i=1, 2, . . . , n) from said input electric signals Ei, respectively, as well as reflected longitudinal waves as delayed electric signals Di (i=1, 2, . . . , n), respectively,
said frequency analyzer causing said electrical coupled-signals Ci and said delayed electric signals Di to interfere respectively, making respective interference signals Ri (i=1, 2, . . . , n), detecting respective amplitudes of said interference signals Ri, clarifying a frequency periodicity Δf from a dependence of said amplitudes on said carrier frequencies fi, and estimating a sound velocity V in said material from said frequency periodicity Δf.

7 more elements

A system for measuring sound velocity in material comprising:

a first piezoelectric substrate;
a first comb-shaped electrode formed on a lower end surface of said first piezoelectric substrate, a lower end surface of said first comb-shaped electrode being in contact with a surface-part of a material;
a second piezoelectric substrate;
a second comb-shaped electrode formed on an upper end surface of said second piezoelectric substrate;
a counter electrode cemented between said first- and second piezoelectric substrates;
a frequency-sweep oscillator generating input electric signals Ei (i=1, 2, . . . , n) with carrier frequencies fi (i=1, 2, . . . , n), respectively;
and
a frequency analyzer,
said first comb-shaped electrode and said counter electrode receiving said input electric signals Ei in turn, radiating longitudinal waves into said material along the direction vertical to said lower end surface of said first piezoelectric substrate, and making the opposite surface-part of said material reflect said longitudinal waves back,
said second comb-shaped electrode and said counter electrode detecting electrical coupled-signals Ci (i=1, 2, . . . , n) from said input electric signals Ei, respectively, as well as reflected longitudinal waves as delayed electric signals Di (i=1, 2, . . . , n), respectively,
said frequency analyzer causing said electrical coupled-signals Ci and said delayed electric signals Di to interfere respectively, making respective interference signals Ri (i=1, 2, . . . , n), detecting respective amplitudes of said interference signals Ri, clarifying a frequency periodicity Δf from a dependence of said amplitudes on said carrier frequencies fi, and estimating a sound velocity V in said material from said frequency periodicity Δf.

8 more elements

Dependencies are inferred from the claim text.