Patent ID: 8373916

Claim:
An optical scanner, comprising: a frame member; a pair of elastic members; and a mirror substrate supported by the pair of elastic members and oscillatable back and forth around the pair of elastic members as a torsion rotational axis, wherein the pair of elastic members are connected with the frame member by a pair of connection members near a coupling end with the frame member, the pair of connection members include a piezoelectric element that generates a torque to drive the mirror substrate, the mirror substrate has a bending rigidity outward from the rotational axis for each area in accordance with a bending moment caused by oscillation and has a rectangular slit at both connection ends with the pair of elastic members, the rectangular slit extends close to both ends of the mirror substrate in a longitudinal direction thereof and maximizes a bending rigidity of an area including a position where a bending moment is maximum when the mirror substrate oscillates, and the mirror substrate includes a rib extending to an end of the mirror substrate in a longitudinal direction thereof on a backside opposite to a mirror surface thereof, wherein the rib width gradually widens in a direction from the rotational axis to the end of the mirror substrate in the longitudinal direction such that the rib width becomes maximum between the rotational axis and the end of the mirror substrate in the longitudinal direction, and the rib width gradually narrows in a direction from the position between the rotational axis and the end of the mirror substrate in the longitudinal direction where the rib width is maximum to the end of the mirror substrate in the longitudinal direction, and the rib width changes so that a ratio of a second moment of area of each area to a bending moment thereof is almost fixed.