Ultrasonic probe

An ultrasonic probe including:

• a group of piezoelectric elements comprising of a plurality of piezoelectric elements of a narrow strip shape arrayed in a long-axis direction thereof;
• and a rotation mechanism that oscillates said group of piezoelectric elements to the left and right in a short-axis direction thereof about a center of said long-axis direction;
• wherein said rotation mechanism is provided with a first bevel gear of a circular-arc shape in plan view, a second bevel gear meshing with said first bevel gear and rotating in a horizontal direction, a drive motor that rotates said second bevel gear via a rotation shaft, and a reference position detecting sensor that detects a reference position of a short axis direction of said piezoelectric element group;
• wherein the rotation shaft of said second bevel gear and the rotation shaft of said drive motor are linked by a pulley linkage using a timing belt;
• and also said first bevel gear is formed from a synthetic resin, and said second bevel gear is made of metal, and an optical rotating plate of said reference position detecting sensor that has a boundary region between a light shielding portion and a light transmission portion, is coupled to said rotation shaft, and said light shielding portion and said light transmission portion are formed in sequence with said boundary region as a reference, at a predetermined angle in opposite directions to each other from the center of said optical rotating plate, and also said optical rotating plate, with said boundary region as a reference, is rotated by less than said predetermined angle, and said boundary region is detected by transmission or shielding of light by said light shielding portion and said light transmission portion, and thereby, based on the detected boundary region, a reference position with respect to an object to be detected of said piezoelectric element group is set.