Patent ID: 8701492

Claim:
An ultrasonic measurement apparatus comprising: a two-dimensional array sensor having a plurality of ultrasonic transducer elements arranged two-dimensionally; a transmitting/receiving section that transmits an ultrasonic wave from the two-dimensional array sensor and receives a wave reflected from an inner portion of an object that is to be measured; and a controller that controls the transmitting/receiving section to cause the transmitting/receiving section to transmit the ultrasonic wave and receive the ultrasonic wave; wherein, the two-dimensional array sensor has an inner circumferential portion and an outer circumferential portion, the arrangement of the ultrasonic transducer elements included in the inner circumferential portion being different from the arrangement of the ultrasonic transducer elements included in the outer circumferential portion, a first distance between the gravity centers of each adjacent pair of some of the ultrasonic transducer elements included in the outer circumferential portion is equal to or less than a second distance at which noise such as a grating lobe is caused; a third distance between the gravity centers of each adjacent pair of the other ultrasonic transducer elements included in the outer circumferential portion is larger than the second distance at which noise such as a grating lobe is caused; the controller has an element selecting circuit that selects an element that is to be used from among the plurality of ultrasonic transducer elements that constitute the two-dimensional array sensor; the element selecting circuit selects the ultrasonic transducer elements included in the inner circumferential portion and ultrasonic transducer elements included in the outer circumferential portion so that a fourth distance between the gravity centers of each adjacent pair of the selected transducer elements included in the outer circumferential portion, is equal to or less than a fifth distance at which noise is not caused; said first, second, third, fourth, and fifth distances are measured in a direction obtained by projecting, onto a surface of the array sensor, a transmitting direction when transmitting ultrasonic wave and a receiving direction when receiving ultrasonic waves.