| 摘要 |
A dust-screening member is shaped like a plate as a whole. A vibrating member is adjacent to one side of the dust-screening member and arranged on the surface along the one side. A drive unit is configured to drive the vibrating member to produce a vibration having a vibrational amplitude perpendicular to the surface, on the surface, such that peak ridges of the vibration form a closed loop and an area including a center of the closed loop surrounded by a node area having almost no vibrational amplitude. When a length of a side in a dust-screening member virtual rectangle corresponding to a short side of a vibrating member virtual rectangle is assumed to be LFw, and a length of short side of the vibrating member virtual rectangle is assumed to be WE, WF/LFw has a dimension of 0.095 or greater and 0.105 or less.
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