Thermal recorder with means for improved alignment of thermal head bar and platen roller

Claim 1

A thermal recorder comprising: a housing, a cover mounted to said housing to be pivotable between an open position and a closed position; a platen roller mounted to one of said housing and said cover, and a thermal head bar having an array of heat generating elements and mounted to other of said housing and said cover, said thermal head bar adapted to be pressed together with said platen roller when said cover is in said closed position with said array of heat generating elements of said thermal head bar being laid on a cylindrical surface of said platen roller along a generatrix thereof and to be detached from said platen roller when said cover is in said open position, wherein said thermal head bar has a pair of forks at longitudinally opposite ends thereof, while said platen roller has a pair of circular radial cams arranged coaxially thereto at opposite ends thereof and adapted to be engaged in a corresponding groove of each of said forks so as to radially align said thermal head bar with said platen roller when said thermal head bar and said platen approach to one another, said platen roller further having an axial cam at lest at one end thereof adapted to engage with one of said forks so as to restrict a relative longitudinal position between said thermal head bar and said platen roller, said thermal head bar being mounted to said other of said housing and said cover at a substantially longitudinally central portion thereof with a small play for movement which includes a small shifting in a first direction of longitudinal extension of said thermal head bar; a small shifting in a second direction substantially perpendicular to both said first direction and a direction of extension of said grooves of said forks, and a small rotation around each of first and second rotation axes, said first rotation axis extending substantially in said second direction, said second rotation axis extending substantially in the direction of extension of said grooves of said forks.