Abstract: Disclosed herein is a method for determining a frequency of a power brush in a vacuum cleaner. According to the method of the present invention, a mechanical oscillation frequency of a driving unit, which includes a brush body reciprocated within a range of prescribed angles, and a torsion bar for providing a prescribed elastic force to angular rotation of the brush body, is set equally to a driving frequency of a power supply unit, which drives the driving unit, or is set a prescribed percentage higher or lower than the driving frequency of the power supply unit, so that the driving unit can resonate. A large amount of movement is obtained using a small amount of power by means of the resonance.

Abstract: A swing motor having an opening formed asymmetrically inside a stator. The swing motor is formed with an asymmetrical opening, in particular in a semicircular shape inside the stator. The opening is provided with a plurality of salient poles wound with coils. Electric current alternately flows through the coils so that a rotor, installed in the stator in a state of being spaced apart from the stator, can reciprocally move. Since the height of the stator is reduced by forming the opening asymmetrically in comparison with the case of forming the opening symmetrically, it is advantageous for minimizing the size of the product in which the swing motor is installed.