Piezoelectric element, piezoelectric device, and manufacturing method of piezoelectric element

A piezoelectric device for detecting pressure, comprising:

• a piezoelectric element including a support member and a vibrating portion;
• and
• a control section configured to perform a predetermined processing, wherein
• the vibrating portion is disposed on the support member and has a piezoelectric film and an electrode film electrically connected to the piezoelectric film, a support region supported by the support member, and a plurality of vibration regions, one end portion side of which is supported by the support region, and the other end portion side of which is opposite to the one end portion is floating from the support member,
• a plurality of the piezoelectric elements includes
• a piezoelectric element having a vibration region in which a mass on the one end portion side is larger than the mass on the other end portion side and serves as a pressure detection section that outputs a first detection signal based on the charge of the piezoelectric film, and
• a piezoelectric element having a vibration region in which a mass on the other end portion side is larger than the mass on the one end portion side and serves as an acceleration detection section that outputs a second detection signal based on the charge of the piezoelectric film, and
• the control section
• calculates a frequency of the applied pressure based on the first detection signal and the second detection signal,
• compares the calculated frequency with a predetermined threshold value,
• detects the pressure based on the second detection signal when it is determined that the calculated frequency is less than the predetermined threshold value, and
• detects the pressure based on the first detection signal when it is determined that the calculated frequency is equal to or greater than the predetermined threshold value.

A manufacturing method of a piezoelectric element, the piezoelectric element including

• a support member,
• a vibrating portion configured to be disposed on the support member and having a piezoelectric film and an electrode film electrically connected to the piezoelectric film, and a support region supported by the support member, and a plurality of vibration regions, one end portion side of which is supported by the support region, and the other end portion side of which is opposite to the one end portion is floating from the support member, and
• the plurality of vibration regions including
• a first vibration region in which a mass on the one end portion side is heavier than the mass on the other end portion side, and which serves as a pressure detection section configured to output a first detection signal based on the charge of the piezoelectric film, and
• a second vibration region in which the mass on the other end portion side is heavier than a mass on one end portion side, and which serves as an acceleration detection section configured to output a second detection signal based on the charge of the piezoelectric film,
• wherein the first vibration region and the second vibration region are arranged adjacent to each other and have a same thickness in a thickness direction,
• the method comprising:
• preparing the support member;
• forming the piezoelectric film and the electrode film on the support member;
• forming a vibration region constituent part by forming a slit that penetrates the piezoelectric film and reaches the support member;
• and
• forming a recess portion from a side of the support member opposite to the piezoelectric film side to float the vibration region constituent part so as to configure the vibration portion having the vibration region, wherein
• when configuring the vibrating region by forming the slit, the slit is formed so that the vibration region, in which the mass on the one end portion side is made heavier than the mass on the other end portion side and serving as the pressure detection section, is configured and the vibration region, in which the mass on the other end portion side is made heavier than the mass on the one end portion side and serving as the acceleration detection section, is configured.