Patent ID: 11793619

Abstract:
A personal hygiene device has a drive unit having a support, a stator fixedly mounted at the support, and an armature spring-mounted at the support for driven linear oscillating motion along a first longitudinal direction parallel to or coinciding with an x-axis of an x-y-z coordinate system. The armature has a center of gravity located in rest at a coordinate [xa, ya, za], and a drive shaft fixedly coupled with the armature and having a center of gravity located in rest at a coordinate [xd, yd, zd]. A first treatment head assembly, detachably connected to the drive shaft, has a center of gravity located in rest at a coordinate [xt1, yt1, zt1]. A secondary mass element, spring-mounted at the support for essentially linear oscillating motion along the first longitudinal direction, has a center of gravity located in rest at a coordinate [xm, ym, zm]. At least the coordinate [xa, ya, za] of the center of gravity of the armature has an offset in at least one of the y-direction and z-direction with respect to the coordinate [xd, yd, zd] of the center of gravity of the drive-shaft or with respect to the coordinate [xt1, yt1, zt1] of the center of gravity of the first treatment head assembly, i.e., ya≠yd and/or ya≠yt1 and/or za≠zd and/or za≠zt1; and the secondary mass element is configured such that the coordinate [xm, ym, zm] of the center of gravity of the secondary mass element is aligned with the coordinate [xj, yj, zj] of the joint center of gravity of the drive shaft, the first treatment head assembly and the armature in the at least one offset direction, i.e., ym=yj and zm=zj, so that a line connecting the coordinate [xm, ym, zm] of the center of gravity of the secondary mass element and the coordinate [xj, yjzj] of the joint center of gravity is parallel to or coincides with the x-axis.