A recording-paper-roll supporting device, comprising:
- a first member;
- and
- a second member,
- wherein,
- (a) the first member includes
- (i) an insertion portion inserted into a center hole of a recording paper roll at an end of the recording paper roll, the recording paper roll being obtained by winding a sheet of recording paper into a roll,
- (ii) a supporting portion provided at an end of the insertion portion, and
- (iii) a support shaft provided at an end of the supporting portion, the supporting portion (1) an outer peripheral surface which is coaxial with the insertion portion,(2) a plurality of insertion-portion-side cam surfaces provided at an end of the outer peripheral surface that is adjacent to the insertion portion, the insertion-portion-side cam surfaces facing the outer peripheral surface in an annular area outside the outer peripheral surface in a radial direction and being disposed at different phases in a circumferential direction and at different heights in an axial direction, (3) a collar portion provided at an end of the outer peripheral surface that is adjacent to the support shaft and having a diameter larger than a diameter of the outer peripheral surface at the end adjacent to the support shaft, (4) a plurality of support-shaft-side cam surfaces provided at an end of the collar portion that is adjacent to the support shaft and being disposed at different phases in the circumferential direction and at different heights in the axial direction, and (5) a cut section formed in an outer peripheral area of the collar portion,
- (b) the second member includes
- (i) a cylindrical portion having an inner peripheral surface along which the outer peripheral surface is inserted,
- (ii) a flange portion provided on the cylindrical portion, the flange portion being coaxial with the cylindrical portion and having a diameter larger than a diameter of the cylindrical portion,
- (iii) a cam follower provided at an end of the cylindrical portion in the axial direction, the cam follower being selectively engageable with the insertion-portion-side cam surfaces, and
- (iv) an engaging claw capable of being inserted through the cut section and being moved on the supporting portion, the engaging claw being selectively engageable with the support-shaft-side cam surfaces, and
- (c) in the state in which the outer peripheral surface is inserted along the inner peripheral surface so that the cylindrical portion is supported by the supporting portion, in which the cam follower is selectively engaged with the insertion-portion-side cam surfaces, and in which the engaging claw is selectively engaged with the support-shaft-side cam surfaces, the engaging claw is elastically deformed in the axial direction by the support-shaft-side cam surface that is engaged with the engaging claw and generates a reactive force which presses the cam follower against the insertion-portion-side cam surface that is engaged with the cam follower, so that the second member is positioned on the supporting portion in the axial direction.