Piezoelectric accoustic sensor with multiple vibrating areas

A piezoelectric element comprising:

• a vibration unit that outputs a pressure detection signal according to a pressure;
• and
• a support member, wherein:
• the vibration unit is arranged on the support member;
• the vibration unit includes a piezoelectric film and an electrode film that is connected to the piezoelectric film and is configured to extract an electric charge generated by a deformation of the piezoelectric film;
• the vibration unit further includes a support region supported by the support member and a plurality of vibration regions connected to the support region and separated from the support member;
• the vibration unit is configured to output the pressure detection signal based on the electric charge;
• each of the plurality of vibration regions has one end portion, which is a boundary with the support region and is a fixed end, and an other end portion, which is a free end;
• a part of each of the plurality of vibration regions on a one end portion side is defined as a first region;
• another part of each of the plurality of vibration regions on an other end portion side is defined as a second region;
• the electrode film is disposed in the first region;
• and
• the piezoelectric element further comprising:
• an improvement unit for improving a detection accuracy of the pressure detection signal, wherein:
• the plurality of vibration regions include a deformation promoting structure that promotes a deformation of the first region as the improvement unit,
• the plurality of vibration regions are divided from each other by a separation slit in the piezoelectric film and the electrode film, the separation slit extends radially from the free end to an end on a support region side, each vibration region of the plurality of vibration regions includes at least a stress increasing slit in the piezoelectric film and the electrode film, the stress increasing slit connects to the end of the separation slit on the support region side, the stress increasing slit extends at an angle from the separation slit and ends at the one end portion on the support region side to divide each vibration region;
• the deformation promoting structure is a corner portion having sides defined by the separation slit and the stress increasing slit;
• and
• the corner portion is in the first region, and a vertex of the corner portion is disposed at an intersection of the separation slit and the stress increasing slit.