A mirror drive device comprising:
- a mirror section that includes a reflective surface configured to reflect light;
- a mirror supporting section that is connected to the mirror section, the mirror supporting section configured to support the mirror section so that the mirror section rotates around a rotating axis;
- a piezoelectric actuator section that is connected to the mirror supporting section, the piezoelectric actuator section configured to generate a driving force that causes the mirror section to rotate around the rotating axis;
- and
- a fixture section configured to support the piezoelectric actuator section,
- wherein the piezoelectric actuator section has a lamination structure in which a diaphragm, a lower electrode, a piezoelectric body, and an upper electrode are laminated in this order, and includes a first actuator section and a second actuator section that are piezoelectric unimorph actuators that are deformed by an inverse piezoelectric effect obtained by applying a drive voltage,
- the first actuator section is arranged on one side of sides that sandwich the mirror supporting section, and the second actuator section is arranged on another side thereof,
- a first base end section on an opposite side to the mirror supporting section in the first actuator section, and a second base end section on an opposite side to the mirror supporting section in the second actuator section are fixed to the fixture sections,
- tilting drive is performed on the mirror supporting section by bending the first actuator section and the second actuator section in opposite directions to each other,
- the upper electrode of the first actuator section includes a first upper electrode section and a second upper electrode section each of which is constituted by one or plurality of electrodes,
- the lower electrode of the first actuator section includes a first lower electrode section that faces the first upper electrode section and a second lower electrode section that faces the second upper electrode section, and each of the first lower electrode section and the second lower electrode section is constituted by one or plurality of electrodes,
- the first actuator section includes a first piezoelectric conversion section that is constituted by the first upper electrode section and the first lower electrode section as an electrode pair, and a second piezoelectric conversion section that is constituted by the second upper electrode section and the second lower electrode section as an electrode pair,
- the upper electrode of the second actuator section includes a third upper electrode section and a fourth upper electrode section, each of which is constituted by one or plurality of electrodes,
- the lower electrode of the second actuator section includes a third lower electrode section that faces the third upper electrode section and a fourth lower electrode section that faces the fourth upper electrode section, and each of the third lower electrode section and the fourth lower electrode section is constituted by one or plurality of electrodes,
- the second actuator section includes a third piezoelectric conversion section that is constituted by the third upper electrode section and the third lower electrode section as an electrode pair, and a fourth piezoelectric conversion section that is constituted by the fourth upper electrode section and the fourth lower electrode section as an electrode pair,
- an arrangement configuration of the first upper electrode section, the second upper electrode section, the third upper electrode section, and the fourth upper electrode section corresponds to stress distribution of a principal stress in an in-plane direction that is perpendicular to a film thickness direction of the piezoelectric body in a resonant mode vibration that is associated with tilting displacement of the mirror section due to the rotation around the rotating axis, and
- stresses in opposite directions to each other are generated between a piezoelectric body portion that corresponds to positions of the first upper electrode section and the third upper electrode section, and a piezoelectric body portion that corresponds to positions of the second upper electrode section and the fourth upper electrode section, in the resonant mode vibration.