Ultrasonic transducer array

Abstract

A plurality of rectangular piezo-electric ultrasonic sector transducers are aligned to form an array, and each transducer has first and second electrodes on its radiating surface. The first electrode is located on a center line of the sector transducer's length, and has a first length in the longitudinal direction and a first width along the center line. Two of the second electrodes are arranged outside the first electrode, symmetrical to the center line. The two second electrodes have a second length in the longitudinal direction longer than the first length, and have a second width which is almost the same as the first width, along a line near the center line. Thus, diamond-shaped electrodes excellent for providing a beam narrow in the longitudinal direction can be employed as the first electrode, and the combination of the first and second electrodes can be connected to each other. The first electrode is designed to provide an ultrasonic beam narrow at a distance shorter than a focal length of an acoustic lens provided on the transducers, and the combination of the first and second electrodes is used to provide an ultrasonic beam narrow in another distance substantially longer than the focal length, so that a sharp beam can be delivered for both the short distance and the long distance.