Expandable column positioning mechanism

摘要

An expandable column 10 is accommodated in an accommodating hole 12a so as to freely advance therefrom and retract thereinto. The expandable column 10 has a plurality of holes 11 disposed thereon in the advancing and retracting direction thereof. An actuating piece 13 extends from an end of a fixed frame 12 in the advancing and retracting direction of the expandable column 10. The actuating piece 13 has elasticity and is formed to be swingable using the connecting portion thereof with the fixed frame 12 as a fulcrum and further has a pin 14 formed thereto and engaged with holes 11. The expandable column 10 is positioned by the engagement of one of the holes 11 with the pin 14 and the engaged state of both the hole 11 and the pin 14 is released by the swing motion of the actuating piece 13, so that the expandable column 10 can be expanded and retracted.