US Patent 7188812 Self-locking support arm

A self-locking support arm is provided, comprising a hang arm and a linked device between a support seat and a connecting seat, which forms a set of four parallel connected rods. Therefore, when the support arm moving up and down, the connecting seat will maintain a fixed angle. A spring device is disposed between the hang arm and the linked device to provide tension of auto homing to the support arm. And, in a rotating joint formed by the linked device and the support seat, a ramp block and a ramp slider block is engaged, to provide an effect of self-locking, and better loading capacity.