Patent ID: 8172323

Claim:
A locking device for a movable member in a chair, comprising: a support member comprising a support base on an upper end of a column of the chair to support a seat and a backrest of the chair; a shaft, the movable member comprising a pivoting member for turning around the shaft together with the backrest pivotally mounted to the support base with the shaft; the movable member is mounted to the support member to move in one direction, a plurality of engagement holes being formed in the support member; a lock pin provided on the movable member to selectively engage in one or more of the plurality of engagement holes in a locked position and to disengage from the one or more of the plurality of engagement holes in an unlocking position to lock the backrest at a tilting angle; an operating member; an actuating member moved by the operating member between a pre-locking position and a pre-unlocking position; an urging unit comprising a first compression spring for urging the lock pin toward the locked position when the actuating member is in the pre-locking position, and a second compression spring for urging the lock pin toward the unlocking position when the actuating member is in the pre-unlocking position; a torsion spring for urging the backrest to return to an upright position, the pivoting member comprising a spring-receiving member receiving the torsion spring; a Bowden cable which comprises an outer tube including a wire, the actuating member comprising a wire end of the wire, the operating member is operable for actuating the wire end and the operating member comprises an operating lever pivotally mounted to the support base, another end of the wire being coupled to the operating lever; and the lock pin slides through a slider, the first compression spring and the second compression spring being in an elongate groove formed in the spring-receiving member, the slider having a hole in which the wire end engages, the wire end operated by the operating lever moving the lock pin via the slider to engage in the one or more of the plurality of engagement holes in the locked position.