PURPOSE: To obtain a better propagation property of ultrasonic waves by forming a metal sound matching layer directly on a surface electrode of a piezo- electric vibrator by electrodiposition so as to eliminate reflection and absorption of the waves due to an adhesive layer.
CONSTITUTION: Piezo-electric vibrators 9 are arranged at an equal interval on an ultrasonic wave absorbing member 10 and fixed on a metalic outer case 11 through an adhesive layer 12. A lead wire 13 is drawn out with connection to a back electrode 14a while a common ground terminals 16 is drawn out with a surface electrode 14b bonded on the perimeter of an inner port of the metalic outer case by an electroconductive adhesive 15. Gaps between the piezo-electric vibrators with a comb-shaped jig 17 and a metal sound matching layer 18 is formed directly on the surface electrode 14b by electroforming. When the thickness of the metal sound matching layer reaches a specified value with the control of the current density and the electrodiposition time, the electroforming is finished and the jig 17 is taken out. A molding agent is injected and enbedded into clearances 19 between piezo-electric vibrators and metal sound matching layers and then, hardened. Thereafter, the surface of the layer is grounded flat to be adjusted to a specified thickness.
IZUMI MAMORU
HONDA HIROKI
