Patent ID: 8753279

Claim:
An ultrasonic probe comprising: a capacitive micro-machine, wherein the capacitive micro-machine comprises: a substrate having a first electrode; and a diaphragm having a second electrode, wherein the diaphragm has its peripheral parts secured to the substrate by means of supporting walls rising from the substrate, wherein a cavity is formed between the substrate and the diaphragm, and is of a cell shape where a distance from the center of the diaphragm to the peripheral parts at which the diaphragm is secured is not uniform, wherein a ratio between a length of the diaphragm in the direction of a first axis and a length in the direction of a second axis perpendicular to the first axis is taken to be a representative aspect ratio, and wherein the representative aspect ratio is set to a value at which a signal level of a locally occurring frequency at which amplitude drops or sensitivity drops within a bandwidth of at least one of transmission and reception by the ultrasonic probe can be suppressed below a predetermined value, and wherein the representative aspect ratio is set a value at which, among vibration modes of the diaphragm, there are six or more vibration modes for which a value obtained by dividing a frequency of a vibration mode having an odd number of anti-nodes by a fundamental mode frequency is 2 or less.