Ink ribbon support mechanism, and printer

An ink ribbon support mechanism, comprising:

• one support member or a plurality of support members;
• and
• a ribbon shaft that supports an ink ribbon, wherein
• two support portions are provided in the one support member or each of the plurality of support members to face each other, or the one support portion is provided in each of the plurality of support members to face each other,
• the ribbon shaft includes, in both end portions thereof, supported portions that engage with the two support portions, respectively,
• one of the two support portions is rotatable,
• one of the rotatable support portion and the supported portion that engages with the rotatable support portion includes a convex portion projecting from an end surface, and another of the rotatable support portion and the supported portion that engages with the rotatable support portion includes a concave portion that is recessed from the end surface and engages with the convex portion,
• the convex portion includes a portion having any one of pentagonal to octagonal truncated pyramid liked shapes extending in an axis direction,
• the concave portion has a polygonal liked shape corresponding to the number of corners of the portion having the truncated pyramid liked shape, and
• at least one of the rotatable support portion and the ribbon shaft includes an elastic member that elastically displaces at least one part of the two support portions and the two supported portions in a withdrawing direction.