Patent ID: 6744457
Filing Date: 2004-06-01
Classification: B41J

Abstract:
A thermal printer comprising: a printing head for printing on paper; a platen having a shaft opposed to the printing head by a small gap for urging the paper against the printing head; a bearing for rotatably holding the platen shaft and having an engagement portion for holding the platen in place, the engagement portion having a symmetrical, non-circular shape with respect to a central axis of the platen shaft; a movable platen frame for selectively moving the bearing between a first position at which the platen is closely spaced from the printing head to perform printing and a second position at which the platen is spaced further apart from the printing head than in the first position; a frame having an engagement groove engageable with the engagement portion of the bearing when the platen is moved into the first position to perform printing, the engagement groove having a shape corresponding to the engagement portion of the bearing; and a lock arm for retaining a part of the bearing and fixing the bearing in engagement with the engagement groove, the lock arm having a platen release mechanism for allowing the platen to be locked and unlocked from the first position.