| 摘要 |
A thermal printer has a printing head, a platen 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, a movable platen frame for moving the bearing between a first position to perform printing and a second position at which the bearing is spaced further apart from the printing head than in the first position, and 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 painting, the engagement groove having a shape corresponding to the engagement portion of the bearing. The engagement portion of the bearing has a symmetrical, non-circular shape with respect to a central axis of the platen shaft, so that idle rotation of the platen bearing is prevented.
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