Hair trimmer with pivotal head, and locking mechanism therefor

A hair trimmer, comprising:

• a handle housing having a pivotal head pivotally mounted thereto and being pivotal about a pivot axis defined by axles of a head housing being received in journals of the handle housing;
• the head housing further supporting a fixed blade and a moving blade, reciprocal relative to the fixed blade in a direction parallel to the pivot axis;
• the head housing further including a plurality of detent grooves radially arranged around the pivot axis and extending axially along an outer surface portion of the head housing;
• a locking button mounted to the handle housing and slidable along the handle housing in a length direction of the handle housing between a first position wherein pivoting of the pivotal head relative to the handle housing is locked, and a second position wherein the pivotal head is manually pivotal relative to the handle housing;
• the locking button being biased towards the first position, the locking button further comprising a depending wall and a cam surface;
• a detent extending between an engagement end and a cam end and having therebetween a detent slot, the engagement end being receivable in any one detent groove define a predetermined pivotal position of the pivotal head relative to the handle housing;
• and
• a biasing element including an inner biasing portion that acts against the depending wall of the locking button to bias the locking button to the first position, and an outer biasing portion received in the detent slot to bias the engagement end of the detent in a direction into the respective detent groove;
• wherein, when the locking button is in the first position, the cam surface of the locking button abuts the cam end of the detent to retain the engagement end of the detent in any one detent groove of the head housing to lock pivotal movement of the pivotal head;
• and
• when the locking button is in the second position, the cam surface of the locking button is retracted relative to the cam end of the detent to permit the detent to move away from the head housing to release the engagement end of the detent from the any one detent groove, thereby permitting the pivotal head to be pivoted relative to the handle housing.