PROBLEM TO BE SOLVED: To provide a piezoelectric sensor and an ultrasonic diagnostic apparatus with an improved S/N ratio in an electric signal in which the strength generated according to the stress of a piezoelectric material is weak.SOLUTION: A piezoelectric plate 201 vibrates when a drive signal is applied to primary electrodes 204 and 205, and a transducer 2a outputs transmission ultrasonic waves toward a subject. The transducer 2a outputs a reception signal from a secondary electrode 206 when a stress is applied to the piezoelectric plate 201 with reflected ultrasonic waves from the subject. A noise output part 19 is connected to the primary electrodes 204 and 205, applies a weak voltage VN including noise to the primary electrodes 204 and 205 when the stress is applied to the piezoelectric plate 201 with the reflected ultrasonic waves, and amplifies the reception signal by a stochastic resonance phenomenon.COPYRIGHT: (C)2013,JPO&INPIT【課題】圧電材料の応力に応じて生じる強度が微弱な電気信号におけるS/Nが改善された圧電センサー及び超音波画像診断装置を提供する。【解決手段】振動子2aは、駆動信号が一次側電極204,205に与えられると圧電板201が振動して被検体に向けて送信超音波を出力するとともに、被検体からの反射超音波によって圧電板201に応力が加えられたときに、該加えられた応力に応じた受信信号を二次側電極206から出力する。ノイズ出力部19は、一次側電極204,205に接続され、圧電板201に反射超音波によって応力が加えられるときに、ノイズを含む微小電圧VNを一次側電極204,205に印加して受信信号を確率共鳴現象により増幅させる。【選択図】図4
