US Patent 7221075 Piezoelectric/electrostrictive device

A piezoelectric/electrostrictive device includes: a ceramic substrate having a thick portion and a thin diaphragm portion; and a piezoelectric/electrostrictive element having a layered structure including a lower electrode, a piezoelectric/electrostrictive film, and an upper electrode, and the thin diaphragm portion of the ceramic substrate is constituted to vibrate in conjunction with the driving of the piezoelectric/electrostrictive element. Furthermore, shape and dimension relations defined in the following (A) to (C) are satisfied: (A) a shape of the thin diaphragm portion 12 is an outward protruding arch shape, and an outward protrusion height of the arch shape is in a range of 5 to 50 μm; (B) a mounting width of the thin diaphragm portion is in a range of 600 to 2000 μm; and (C) a ratio (height/width) of the height to the width of the thick portion is in a range of 0.25 to 3. According to the piezoelectric/electrostrictive device, vibration of a thin diaphragm portion is effectively prevented from being damped, and the device maintains displacement (amplitude) to be high and is superior in response and highprecision (highresolution, high-sensitivity) detection is possible.