Patent ID: 8339510

Claim:
A vibrating device comprising: a vibrator including: a dust-screening member which is shaped like a plate as a whole and has at least one side that is symmetric with resect to a symmetry axis; and a vibrating member secured to the dust-screening member and configured to produce, at the dust-screening member, vibration having a vibrational amplitude perpendicular to a surface of the dust-screening member; and a hold and support member configured to hold and support the vibrator to a fixed member, wherein the hold and support position by the hold and support member is arranged at position along a circle or ellipse concentric to the centroid of the vibrator such that peak ridges of the vibration having a vibrational amplitude perpendicular to the surface of the dust-screening member form closed loops, a drive unit configured to drive the vibrating member to produce vibration Z(x, y) at the dust-screening member, the vibration being expressed as follows: Z ( x,y )= W mn ( x,y )·cos(γ)+ W nm ( x,y )·sin(γ) where Z(x, y) is vibration at a given point P(x, y) on the dust-screening member; m and n are positive integers including 0, indicating the order of natural vibration corresponding to a vibrational mode; W mn ⁡ ( x , y ) = sin ⁡ ( n ⁢ ⁢ π · x + π 2 ) · sin ⁡ ( m ⁢ ⁢ π · y + π 2 ) ; W nm ⁡ ( x , y ) = sin ⁡ ( m ⁢ ⁢ π · x + π 2 ) · sin ⁡ ( n ⁢ ⁢ π · y + π 2 ) ; and γ is +π/4 or ranges from −π/8 to −π/4, wherein the device has such a size that LP/LF is 0.5 or more, but less than 1, where LF is the length of the sides to which the vibrating member is arranged in a virtual rectangle having the same area as the surface of the dust-screening member and sides including the one side, and LP is the longitudinal length of the vibrating member of the sides parallel to the one side.