A portable thermal printer (S) comprising:
- a containment shell (2) having therein:
- a compartment (21) configured to accommodate a roll of paper,
- an access opening (22) designed to allow said compartment (21) to be accessed, and
- a paper output opening or slot (S1);
- a cover (3) configured to close said access opening (22), directly or indirectly hinged to said containment shell (2) and to rotate around a rotation axis (31) from a closed position to an open position;
- a printing mechanism (4) housed in said containment shell (2) and comprising a paper pressing roller (5) positioned adjacently to said paper output opening or slot (S1) and held in that position through a reversible constraint member (41);
- a release mechanism (1) configured to release said paper pressing roller (5);
- wherein said reversible constraint member (41) is configured to engage a rotation pin (51) of the paper pressing roller,
- wherein an insertion/extraction of said rotation pin (51) in/from said constraint member (41) is performed by translating said paper pressing roller (5) according to an exit direction (10) lying on an exit plane,
- wherein said release mechanism (1) is configured to exert a force on said paper pressing roller (5) according to a direction which is parallel to said exit direction (10),
- wherein said release mechanism (1) comprises an arm (11), one end (12) of said arm (11) being constrained to said paper pressing roller (5), a release button (15), accessible from outside of the containment shell (2) and positioned adjacently to said rotation axis (31) of said cover (3), is connected to an opposite end (14) of said arm (11), leaving an external area of said cover (3) free,
- wherein said arm (11) is constrained so that said arm slides with respect to said cover (3), when said cover (3) is closed and when a user acts on said release button (15), between a first backward locking position and a second forward release position, along said exit direction (10), and
- wherein sliding movement of said arm (11) pushes said paper pressing roller (5) in said exit direction (10), extracting said paper pressing roller from said constraint member (41).