Patent ID: 7692346

Claim:
A vibrator comprising: a tubular casing that defines an enclosed space; a coil disposed in the casing in coaxial relation to the casing; a magnetic circuit unit disposed in the casing in coaxial relation to the casing, the magnetic circuit unit having an extent in a radial direction to define a first space and a second space at both sides of the magnetic circuit unit in an axial direction of the tubular casing, and the magnetic circuit unit having an outer peripheral surface positioned adjacent to an inner peripheral surface of the casing with an annular gap interposed between the outer peripheral surface of the magnetic circuit unit and the inner peripheral surface of the casing; a suspension that resiliently supports the magnetic circuit unit such that the magnetic circuit unit is vibratable in the axial direction in response to supply of a signal current to the coil; and a vent passage that provides communication in the casing between the first space and the second space, the vent passage comprising at least one recess that is formed in the inner peripheral surface of the casing and extends between the first space and the second space.