Patent ID: 7917982

Claim:
An electric toothbrush handpiece, comprising: a housing defining an opening and a longitudinal handpiece axis, the housing comprising a first locking element and a brush head drive unit contained within the housing; and a cover comprising a second locking element, wherein the cover is configured to seal the opening when the first and second locking elements are engaged, wherein the housing comprises a first draft engagement surface disposed proximate an edge of the housing surrounding the opening and the cover comprises a second draft engagement surface disposed on a seating surface of the cover that sits on the edge of the housing when the locking elements are engaged, the draft engagement surfaces ascending relative to the longitudinal handpiece axis, at which engagement surface the housing and cover contact each other with the cover sealing the opening, the draft engagement surfaces arranged such that the cover is axially unseatable from the housing by twisting the cover relative to the housing about the longitudinal axis to release the locking elements.