Accessory coupling structure

1. An accessory coupling structure comprising:

a rod-shaped inserting portion attached to a first end of an accessory; and

a receiving portion attached to a second end of the accessory and including an insertion hole that receives the inserting portion, wherein

the receiving portion includes:

a cylindrical slider into which at least a tip end portion of the inserting portion is inserted and which is slidable and rotatable in the insertion hole;

a guide unit configured to restrict a movement of the slider in the insertion hole such that the slider is rotated relative to the insertion hole in response to insertion of the inserting portion, and a position of the slider is therefore switched to a first position or a second position; and

a coupling unit configured to,

when the slider is located at the first position, inhibit a movement of the inserting portion in the receiving portion in a pull-out direction, and

when the slider is located at the second position, allow the inserting portion to move in an insertion direction and the pull-out direction in the receiving portion.

2. The accessory coupling structure according to claim 1 , wherein the inserting portion includes an engagement portion that engages with the coupling unit of the receiving portion when the slider is located at the first position.

3. The accessory coupling structure according to claim 2 , wherein:

the receiving portion includes a stretching member that presses the slider in a direction opposite to the insertion direction of the inserting portion; and

the guide unit switches the position of the slider in the insertion hole to the first position or the second position in accordance with the movement of the slider in the insertion direction by insertion of the inserting portion and the movement of the slider in a pressing direction by pressing of the stretching member.

4. The accessory coupling structure according to claim 3 , wherein:

the guide unit is a guide groove which is formed on an inner peripheral surface of the receiving portion in a circumferential direction of the receiving portion and has a periodical concave-convex shape, the inner peripheral surface forming the insertion hole;

the slider includes a plurality of locking pins which move along the guide groove and respectively engage with concave portions of the guide groove when the slider is located at the first position or the second position; and

each of the concave portions with which the locking pins respectively engage when the slider is located at the first position and each of the concave portions with which the locking pins respectively engage when the slider is located at the second position are respectively formed at positions different from each other in the insertion direction of the inserting portion.

5. The accessory coupling structure according to claim 3 , wherein:

the guide unit is a concave-convex portion formed in a circumferential direction of the slider and having a periodical concave-convex shape;

the receiving portion includes a locking pin formed in the insertion hole of the receiving portion so as to project toward the slider;

the slider rotates while the concave-convex portion and the locking pin contact each other, and when the slider is located at the first position or the second position, the locking pin engages with one of concave portions of the concave-convex portion; and

the concave portion with which the locking pin engages when the slider is located at the first position and the concave portion with which the locking pin engages when the slider is located at the second position are respectively formed at positions different from each other in the insertion direction of the inserting portion.

6. The accessory coupling structure according to claim 3 , wherein:

the guide unit is a concave-convex portion formed in a circumferential direction of the slider and having a periodical concave-convex shape;

the receiving portion includes a locking pin formed in the insertion hole of the receiving portion so as to project toward the slider;

the slider rotates while the concave-convex portion and the locking pin contact each other, and when the slider is located at the first position or the second position, the locking pin engages with one of concave portions of the concave-convex portion; and

the concave portion with which the locking pin engages when the slider is located at the first position and the concave portion with which the locking pin engages when the slider is located at the second position are respectively formed at positions different from each other in a circumferential direction of the receiving portion.

7. The accessory coupling structure according to claim 4 , wherein:

the locking pins are movable in a direction perpendicular to the insertion direction of the inserting portion and toward an inside of the slider into which the inserting portion is inserted;

the inner peripheral surface of the receiving portion on which the concave portions, with which the locking pins respectively engage when the slider is located at the first position, of the guide groove are formed tapers in a pull-out direction of the inserting portion; and

the plurality of locking pins that engage with the guide groove as the coupling unit contact the inner peripheral surface of the receiving portion and move toward the inside of the slider to inhibit the movement of the inserting portion in the pull-out direction.

8. The accessory coupling structure according to claim 5 , wherein the slider includes as the coupling unit a plate spring which contacts at least a part of an inner peripheral surface of the slider when the slider is located at the first position, to deform to inhibit the movement of the inserting portion in the slider in the pull-out direction.

9. The accessory coupling structure according to claim 6 , wherein the receiving portion includes as the coupling unit a plate spring which contacts at least a part of an inner peripheral surface of the slider when the slider is located at the first position, to deform to inhibit the movement of the inserting portion in the insertion hole in the pull-out direction.