| 摘要 |
PURPOSE:To remove water drops deposited on a board-like member nearly uniformly over the whole face of the board-like member by fixing an oscillator having an annular electrostrictive element to a part of the swingably supported board-like member and oscillating the oscillator to repeatedly bend the board- like member. CONSTITUTION:A piezoelectric oscillator 20 in which electrodes 21, 22 are integrally provided on both end faces of an annular electrostrictive element 24 is fixed nearly to the center portion of the mirror 11 of each vehicle side mirror by means of an adhesive. The electrodes 21, 22 are connected to an oscillating circuit via lead wires 31, 32 and AC power is applied to the piezoelectric oscillator 20, expanding/contracting same in the thickness and radial directions to repeatedly bend the mirror 11. Thereby, water drops deposited on the surface of the mirror 11 are shaken off and removed. In this case, the frequency of the AC power is selected to be in the vicinity of the integral multiples of the minimum resonance frequency of the mirror 11 to resonate the mirror 11, thereby generating uniform standing waves with a large amplitude on the whole mirror 11 to improve the removing efficiency of water drops. |
