Patent ID: 8806691

Claim:
An electric toothbrush, comprising: a motor; a case which accommodates the motor; an eccentric shaft having a first end and a second end, the first end thereof fixed to a rotation shaft of the motor and the second end thereof held by the case, the eccentric shaft being able to rotate in a forward direction and a reverse direction by the motor; a brush component mounted on the case; and a gravity center horizontally shifting arrangement having a lower weight and an upper weight provided in the eccentric shaft and aligned along the rotation shaft so as to locate the lower weight closer to the motor than the upper weight, at least one of the upper weight and lower weight being configured to angularly rotate between a first engaged position and a second engaged position about the rotation shaft, whereby the gravity center in a radial direction of a center axis of the eccentric shaft is shifted to a first radial position spaced from and close to the center axis when the eccentric shaft is rotated in the forward direction to rotate the weight to the first engaged position, and the gravity center is shifted to a second radial position further away from the center axis than the first radial position when the eccentric shaft is rotated in the reverse direction to rotate the weight to the second engaged position.