A piezoelectric-driven optical reflection element capable of securing a predetermined deflection angle of a mirror part thereof even when a high-frequency driving section thereof operates at higher frequencies for increasing resolution of a projected image has been desired.
As a way to meet the demand, an optical reflection element including a meandrous vibrating part is known.
FIG. 6 is a perspective view of conventional optical reflection element 501 described in Patent Literature 1. High-frequency driving section 502 of optical reflection element 501 includes mirror part 30, a pair of meandrous vibrating parts 31 that face each other across mirror part 30, and frame 32 that surrounds mirror part 30 and the pair of meandrous vibrating parts 31. One end of each of the pair of meandrous vibrating parts 31 is connected with mirror part 30. The other end of each of the pair of meandrous vibrating parts 31 is connected with frame 32. Driving sections are disposed on each of meandrous vibrating parts 31. Each of the driving sections includes a lower electrode, a piezoelectric body disposed on the lower electrode, and an upper electrode disposed on the piezoelectric body. An alternating-current (AC) voltage applied to the piezoelectric body via the lower electrode and the upper electrode resonance drives mirror part 30 connected with the one end of respective meandrous vibrating parts 3, thereby causing mirror part 30 to rotate back and forth.
The meandrous shape of vibrating parts 31 of high-frequency driving section 502 allows the displacement of vibrating parts 31 to accumulate. In addition, the resonant driving increases a deflection angle of mirror part 30 with a lower voltage, thereby providing a predetermined deflection angle.
In conventional optical reflection element 501, in order to cause mirror part 30 to rotate back and forth largely, curved portions of meandrous vibrating parts 31 may break, thus hardly increasing the deflection angle of mirror part 30.