Patent ID: 7358633

Claim:
A linear vibration motor using resonance frequency, comprising: a movable unit having a magnet, a yoke for housing the magnet and a weight having a predetermined mass for surrounding the flank of the yoke; a base assembly placed under the movable unit, and having a coil assembly; a housing for covering the base assembly and the movable unit placed over the base assembly; an elastic member being shaped as a leaf spring, the elastic member including an outer planar section fixed to a ceiling of the housing or a top of the base assembly, an inner planar section opposed to the outer planar section and connected to a top or bottom of the movable unit and at least two connecting sections for connecting the inner planar section with the outer planar section along curved lines, the inner planar section having a diameter matching about 15 to 70% of the outside diameter of the movable unit, and the elastic member being deformable to the extent that the inner and outer planar sections are shifted to a coplanar position from a parallel position where they are spaced for a predetermined distance from each other; and magnetic fluid formed on the top or bottom of the movable unit; whereby the movable unit vibrates vertically under the interaction between a magnetic force generated from the magnet and an electromagnetic force of a predetermined frequency generated from the coil assembly; and wherein the magnetic fluid reduces contact noises generated from the vertical vibration of the movable unit.