US Patent 7093644 Window covering with lifting mechanism

A window covering, a lifting mechanism for a window covering and a locking device for a lifting mechanism are disclosed. The lifting mechanism includes main body, a pair of cord spools rotatably mounted to the main body, and a pair of coil springs that rotate a member separate from the cord spools, and the member rotates the spools to wind the cord onto the spools. The locking device includes a main body, a cord slot associated with the main body and a locking arm having a cord channel in sliding engagement with the main body and having a channel, and a biasing mechanism to move the cord channel out of alignment with the slot and releasably lock the cord in position