A compacting tool includes an upper mass, a lower mass coupled to the upper mass, a driving axis extending centrally through the upper mass and the lower mass, a motive source supported by the upper mass, the motive source including an output shaft, a battery configured to provide power to the motive source, a handle coupled to the upper mass, a user interface supported by the handle and configured to receive an input to control the motive source, and a drive mechanism configured to convert rotational movement of the output shaft to reciprocating movement of the lower mass. The drive mechanism includes a multi-stage transmission operatively coupled between the output shaft of the motive source and the lower mass.

Embodiments of the invention provide a piezoelectric vibration module, including a vibration plate mounted with a piezoelectric element, which generates a vibration force in a vertical direction by being repeatedly expanded and contracted depending on external power applied thereto, and a lower case coupled with both ends of the vibration plate so as to be spaced apart from the vibration plate. The piezoelectric vibration module further includes a bar-shaped weight body increasing the vibration force of the piezoelectric element, and an elastic member interposed between the vibration plate and the weight body.

Embodiments of the invention provide a piezoelectric vibration module, including a vibration plate mounted with a piezoelectric element, which generates a vibration force in a vertical direction by being repeatedly expanded and contracted depending on external power applied thereto, and a lower case coupled with both ends of the vibration plate so as to be spaced apart from the vibration plate. The piezoelectric vibration module further includes a bar-shaped weight body increasing the vibration force of the piezoelectric element, and an elastic member interposed between the vibration plate and the weight body.

There is provided a vibration generating device including: a housing having an internal space; a vibration member having one end fixedly attached to the housing; a piezoelectric element installed on the vibration member; and a mass body fixedly attached to the vibration member, wherein the vibration member includes an installation part on which the piezoelectric element is installed, and an extension part extended from at least one side surface of the installation part, and a maximum displacement portion of the vibration member is changed depending on a vibration mode.

There is provided a vibration generating device including: a housing having an internal space; a vibration member having one end fixedly attached to the housing; a piezoelectric element installed on the vibration member; and a mass body fixedly attached to the vibration member, wherein the vibration member includes an installation part on which the piezoelectric element is installed, and an extension part extended from at least one side surface of the installation part, and a maximum displacement portion of the vibration member is changed depending on a vibration mode.

A clothes treatment apparatus includes a frame; a hanger body configured to move with respect to the frame and provided to hang clothes or clothes hangers; a vibration module that generates vibrations by comprising at least one eccentric portion that rotates around at least one predetermined rotational axis in such a way that the weight is off-center, and that is connected to the hanger body to transmit the vibrations; and at least one elastic member that exerts an elastic force on the vibration module when the vibration module vibrates. The angular speed of the eccentric portion is changeable.

A clothes treatment apparatus includes a frame; a hanger body configured to move with respect to the frame and provided to hang clothes or clothes hangers; a vibration module that generates vibrations by comprising at least one eccentric portion that rotates around at least one predetermined rotational axis in such a way that the weight is off-center, and that is connected to the hanger body to transmit the vibrations; and at least one elastic member that exerts an elastic force on the vibration module when the vibration module vibrates. The angular speed of the eccentric portion is changeable.

An undulatory structure and methods for the fabrication and use thereof. The undulatory structure includes a buckled sheet and one or more work input elements for deforming the buckled sheet in an undulating manner wherein each point in a series of points on a sinuously-shaped profile of the buckled sheet travels at least partially along a figure eight-shaped path. The undulatory structure can be adapted for use as a solid-state transducer wherein the buckled sheet provides mechanical advantage without appreciable opposition from elastic restoring forces, thereby achieving improved force, displacement and efficiency characteristics.

An undulatory structure and methods for the fabrication and use thereof. The undulatory structure includes a buckled sheet and one or more work input elements for deforming the buckled sheet in an undulating manner wherein each point in a series of points on a sinuously-shaped profile of the buckled sheet travels at least partially along a figure eight-shaped path. The undulatory structure can be adapted for use as a solid-state transducer wherein the buckled sheet provides mechanical advantage without appreciable opposition from elastic restoring forces, thereby achieving improved force, displacement and efficiency characteristics.

An electronic device includes a housing having a plurality of surfaces and a plurality of vibration portions provided in the housing so as to be in contact with at least one of the plurality of surfaces. The plurality of vibration portions include a first vibration portion, which vibrates at a frequency included in a first frequency band, and a second vibration portion, which vibrates at a frequency included in a second frequency band that is different from the first frequency band.