PURPOSE: To prevent a cable from being damaged or worn due to an external cause by using a mold member whose inner layer is made of a material with low water absorption performance and high specific resistivity and whose outer layer is made of a material with excellent impact and wear resistance and close adhesion with a cable and its inner layer so as to cover the entire inner layer and ends of the cable.
CONSTITUTION: The mold member 10 is of two layer structure comprising an inner layer 10a and an outer layer 10b and an ethylene propylene rubber is used for the inner layer 10a. Since the specific resistivity of the ethylene propylene group rubber is 1015ohm-cm or over and its water absorption rate is 0.1%/24hr or below, even when an ultrasonic wave transmitter-receiver is in use for applications in which the transmitter-receiver is left in sea water for a long period, the deteriorated insulating performance resulting from invasion of sea water passing through the inner layer 10a and reaching a piezoelectric ceramic 1 is not caused. The outer layer 10b uses a chloroplene rubber or urethane rubber or epoxy resin or the like, and the type of the material is excellent in impact and wear resistance and in adhesion with the surface of the inner layer 10a and the cable 8.
UCHINO HIROYUKI
OMURA MITSUO
