Patent ID: 7760227

Claim:
A deflector, comprising: a vibrating mirror to reciprocally scan a beam from a light emitting source, the vibrating mirror including a vibrating plate part supported by a torsion beam, the torsion beam provided as a rotational axis, and a movable mirror having a first edge and a second edge, the movable mirror formed in a body with the vibrating mirror; and a rotational part configured to give a rotational torque to the vibrating mirror for making oscillation, the rotational torque being generated along a first side of the vibrating plate part, the first side having a width D and being parallel with and spaced apart from the rotational axis by length R in a direction perpendicular to the rotational axis, such that the first side of the vibrating plate part is nearer to the rotational axis than the first edge of the movable mirror, wherein the vibrating mirror has relationships of R<r,D>d ,and D≧d ·( r/R )^2 where a width of the second edge of the movable mirror in a direction perpendicular to the rotational axis is 2r, such that the width 2r of the second edge of the movable mirror is greater than a width 2R of a second side of the vibrating plate part, the second side of the vibrating plate part being perpendicular to the rotational axis; a width of the first edge of the movable mirror in a direction parallel with the rotational axis is d, such that the width D of the first side of the vibrating plate part is greater than the width d of the first edge of the movable mirror.