According to an aspect there is provided a drivetrain assembly (1) for a personal care device (10). The drivetrain assembly (1) comprising: a shaft (2); a frame (4) comprising an opening in a surface (4a) of the frame (4) through which the shaft (2) extends; and an abutment (3) provided in cooperation with the shaft (2). An engagement surface (3a) of the abutment (3) is configured to engage with the surface (4a) of the frame (4) such that relative movement between the frame (4) and the shaft (2) in a given direction (d) is inhibited past a threshold distance.

An electromagnetic transducer, including a plurality of static flux paths, and a plurality of dynamic flux paths, wherein at least two of the plurality of static flux paths lie in respective first planes parallel and offset from one another, at least two of the plurality of dynamic flux paths lie in respective second planes parallel and offset from one another, and the first planes and the second planes are arrayed so as to establish at least a general tic-tac-toe lattice.

An electromagnetic transducer, including a plurality of static flux paths, and a plurality of dynamic flux paths, wherein at least two of the plurality of static flux paths lie in respective first planes parallel and offset from one another, at least two of the plurality of dynamic flux paths lie in respective second planes parallel and offset from one another, and the first planes and the second planes are arrayed so as to establish at least a general tic-tac-toe lattice.

An actuator may include a movable body; a support body; a connecting body; and a magnetic driving circuit. The magnetic driving circuit may include an air-core coil provided in a first member, and a first permanent magnet provided in a second member so as to face the coil on a first side in a first direction. The magnetic driving circuit may cause the movable body to vibrate with respect to the support body in a second direction which intersects with the first direction. The first member may include a coil holder comprising a plate part in which a coil placement hole is formed, a first plate that overlaps the coil placement hole and the plate part, and an adhesive layer. The coil may face the first permanent magnet via the first plate.

An actuator may include a movable body; a support body; a connecting body disposed in contact with both the movable body and the support body in a position in which the movable body and the support body face each other; and a magnetic driving circuit including a coil in the support body and a permanent magnet in the movable body. The magnetic driving circuit may cause the movable body to vibrate. The support body may include a coil holder that holds the coil, a case that covers a circumference of the movable body and the coil holder, and a power supply board held by the coil holder in a position exposed from the case and to which a coil wire forming the coil is connected.

An actuator may include a movable body; a support body; a connecting body disposed in contact with both the movable body and the support body; and a magnetic driving circuit including a coil provided in a first member, and a permanent magnet provided in a second member. The magnetic driving circuit may vibrate the movable body. The first member may include a coil holder and a power supply board. Both end portions of the power supply board may fit, from a second side in the first direction, inside of a pair of slits extending to a first side in the first direction. The power supply board may fit in the pair of slits to a depth in which the power supply board is in contact with a contact portion of the coil holder. The coil wire may be slackened in a section between the coil and a connecting position.

An actuator may include a movable body; a support body; a connecting body disposed in contact with both the movable body and the support body; and a magnetic driving circuit including a coil provided in a first member, and a permanent magnet provided in a second member. The magnetic driving circuit may vibrate the movable body. The first member may include a coil holder and a power supply board. Both end portions of the power supply board may fit, from a second side in the first direction, inside of a pair of slits extending to a first side in the first direction. The power supply board may fit in the pair of slits to a depth in which the power supply board is in contact with a contact portion of the coil holder. The coil wire may be slackened in a section between the coil and a connecting position.

A linear vibration motor having elastic pieces provided with vibration arms comprises housing, a mass block, and elastic pieces. The elastic pieces connect the mass block and the housing to provide an elastic force in Z axis direction such that the mass block performs a movement up and down. The elastic pieces are provided with two vibration arms, and the two vibration arms are symmetrical about the X axis when rotating 180 degrees around the X axis. The elastic pieces are S-shaped or inverted Z-shaped, or formed by the combination of two V-shaped vibration arms. The elastic pieces have two or four elastic pieces, and disposed on symmetrical two sides of the mass block.

A linear vibration motor having elastic pieces provided with vibration arms comprises housing, a mass block, and elastic pieces. The elastic pieces connect the mass block and the housing to provide an elastic force in Z axis direction such that the mass block performs a movement up and down. The elastic pieces are provided with two vibration arms, and the two vibration arms are symmetrical about the X axis when rotating 180 degrees around the X axis. The elastic pieces are S-shaped or inverted Z-shaped, or formed by the combination of two V-shaped vibration arms. The elastic pieces have two or four elastic pieces, and disposed on symmetrical two sides of the mass block.

Provided is a linear vibration motor, including: a housing; a vibration unit received in the housing, including a mass with a through hole and a permanent magnet mounted in the through hole; an elastic module; and a driving unit including an iron core fixedly mounted in the housing and passing through the through hole and a coil. The iron core includes an iron core body portion passing through the through hole and two iron core propping portions extending from two ends of the iron core body portion facing away from a central axis of the iron core body portion. The coil is wound on the iron core body portion. A side of the permanent magnet close to the coil and a side of the permanent magnet close to the mass have opposite magnetic polarities, and after the coil is energized, the two iron core propping portions have opposite magnetic polarities.