Appeal No. 1998-2443
Application No. 08/704,956
a thick wall would be, larger displacements are generated at the metal-liquid interface,
resulting in larger signal amplitudes.
Claim 21 is reproduced as follows:
21. A method of ultrasonically inspecting liquid contents in a container to
determine a liquid level H therein, the container having a thin metal wall in
contact with the liquid contents and forming at least one wall of the container,
comprising the steps of:
providing an electromagnetic acoustic transducer (EMAT) assembly
proximate to the thin metal wall to produce and cause a magnetic field to
exist therein;
energizing an eddy current coil of the EMAT assembly with an RF
toneburst signal of known amplitude and frequency to generate a Lorentz
force in the thin metal wall and cause it to vibrate and launch ultrasonic
compressional waves into the liquid contents in contact with the thin metal
wall;
allowing the compressional waves to travel through the liquid contents
and reflect off an interface, the reflected ultrasonic compressional waves
returning through the liquid contents to the thin metal wall in contact therewith
and causing the thin metal wall to vibrate in the presence of the magnetic
field produced by the EMAT transducer assembly, the vibrations of the thin
metal wall inducing a voltage in the eddy current coil of the EMAT transducer
assembly; and
measuring a time of flight of the ultrasonic compressional waves
through the liquid contents, and using a preestablished value for a velocity of
the ultrasonic compressional waves within the liquid contents, calculating the
level H of the liquid contents using the measured time of flight and the
preestablished velocity value.
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