Appeal No. 2005-2035 Page 4
Application No. 10/281,417
With this as background, we analyze the prior art applied by the examiner in the
rejection of the claims on appeal.
Dias shows in Figure 1 the basic construction of a previously known ultrasound
diagnostic probe 20. The probe 20 consists of a catheter 22, a piezoelectric transducer
24 at the distal end 38 of the catheter, electric wires 26 that connect piezoelectric
transducer 24 to external circuitry at the proximal end, an acoustic reflector 28 at the
distal end, a rotating drive shaft 34 coupled to a small motor/shaft encoder at the
proximal end, and a plastic radome 30 (i.e., an acoustic window that has the same
acoustic impedance as a fluid) filled with a liquid 32 that fits over piezoelectric
transducer 24 and acoustic reflector 28. Piezoelectric transducer 24 is stationary and
when excited by an external source, it produces an acoustic signal 36 that travels
through the liquid in radome 30 and strikes acoustic reflector 28. The surface of
acoustic reflector 28 resides at an angle of 45° from acoustic signal 36 and it reflects
acoustic signal 36 at an angle of 90° from its original path. The reflected acoustic signal
36 travels through liquid 32 in radome 30 and propagates through the blood until it
encounters the arterial wall. Depending on the penetration into the arterial wall, several
echoes return to piezoelectric transducer 24 by retracing essentially the same path.
Piezoelectric transducer 24 converts these echoes into corresponding electrical pulses
and wires 26 carry these electrical pulses to electrical circuitry located at the proximal
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