Micromirror device

A micromirror device, comprising:

• a mirror part that has a reflecting surface configured to reflect incident light;
• an actuator that has an annular shape and surrounds the mirror part;
• a first connecting part that connects the mirror part and the actuator, such that the mirror part is rotatable around a first axis;
• a fixing part that is provided at an outer periphery of the actuator;
• and
• a second connecting part that connects the actuator and the fixing part, such that the actuator is rotatable around a second axis intersecting the first axis, wherein:
• the actuator applies a rotational torque around the first axis to the mirror part and applies a rotational torque around the second axis to the mirror part so as to rotationally drive the mirror part around the first axis and the second axis,
• the actuator is a piezoelectric actuator including a piezoelectric element comprising a lower electrode, a piezoelectric film, and an upper electrode laminated on an oscillation plate, and
• the upper electrode consists of a plurality of individual electrode parts, each of which is separated by a first stress inversion region and a second stress inversion region, and the piezoelectric element includes a plurality of piezoelectric parts respectively defined by the plurality of individual electrode parts, the first stress inversion region being a region in which positive and negative, of a principal stress component having a maximum absolute value among a principal stress generated in an in-plane direction of the piezoelectric film, are inverted in a maximum displacement state, in a case of driving in a first resonance mode in which the mirror part is tilted and oscillated around the first axis, and the second stress inversion region being a region in which positive and negative, of a principal stress component having a maximum absolute value among a principal stress generated in the in-plane direction of the piezoelectric film, are inverted, in a case of driving in a second resonance mode in which the mirror part is tilted and oscillated around the second axis.