PRINTING UNIT AND THERMAL PRINTER

摘要

A printing unit, comprising: a main body frame; a platen roller removably mounted on the main body frame; a lock mechanism supported on the main body frame so as to be pivotable between a locking position where the platen roller is held on the main body frame in a rotatable manner and an unlocking position where the platen roller is detachable from the main body frame; a thermal head held in press contact with an outer peripheral surface of the platen roller; a pivot shaft provided to one of the main body frame and the lock mechanism and inserted through shaft holes formed in another of the main body frame and the lock mechanism, the pivot shaft being configured to pivot the lock mechanism relative to the main body frame about the pivot shaft; and biasing members configured to bias the lock mechanism toward the locking position and bring the pivot shaft and opening edges of the shaft holes into abutment against each other.

主权项

1. A printing unit, comprising:
a main body frame; a thermal head mounted on the main body frame; a platen roller arranged to oppose to the thermal head, wherein the platen roller is configured to rotate about an axis extending along a first direction and covey a recording sheet nipped between the platen roller and the thermal head; roller insertion grooves formed in the main body frame to receive the platen roller therein, wherein the platen roller is removable from the roller insertion grooves along a second direction orthogonal to the first direction; a lock arm supported for rotation with a pivot shaft extending along the first direction, wherein the lock arm is movable to take a first position in which the platen roller is locked in the roller insertion grooves, a second position in which the platen roller is unlocked in the roller insertion grooves and a third position in which the platen roller is releasable from the roller insertion grooves; a moving mechanism configured to move the lock arm from the first position to the second position and from the second position to the third position; a biasing member operable to bias the lock arm to stay in the first position when the lock arm is in the first position and to move back to the first position when the lock arm is in the second position; and a gripping portion provided to the lock arm and having an engaging hook movable to (i) engage, when the lock arm is in the first position, with the platen roller so that the platen roller is locked in the roller insertion grooves and the lock arm is locked in the first position, (ii) disengage, when the lock arm is in the second position, from the platen roller so that the platen roller is unlocked in the roller insertion grooves and the lock arm is unlocked to become movable away from the platen roller and (iii) when the lock arm is in the third position, clear a way in which the platen roller is released from the roller insertion grooves.