Spring lock mechanism

Abstract

Provided is a spring lock mechanism including: a lock drum () provided on either one of a first member () and a second member (); a coil spring () secured to the other member, abutting on the lock drum (), and locking turning of the second member () in one direction relative to the first member () due to a frictional force; and a switching mechanism causing the second member () to turn relative to the first member () to switch a state in which the locking has been established and a state in which the locking has been released and held, in which the coil spring () abuts on an inner circumferential surface of the lock drum (), the diameter of the coil spring () increases through compression of a spring wire material of the coil spring () in a longitudinal direction caused by the turning of the second member (), the coil spring thus further presses the inner circumferential surface of the lock drum () and locks the turning due to the frictional force, and the switching mechanism accompanies an operation of extending or shortening a length of the coil spring () in the state in which the locking has been released relative to the length of the coil spring () in the state in which the locking has been established.