US Patent 7261138 Child safe cord lock

A cord lock for window coverings has one or more cams adjacent a surface over which a one or more lift cords travel. The cams are spring biased to a locked position in which they press the lift cords against the surface. A cam lock with a release cord is provided which engages and moves the cams from a locked position to an unlocked position in which the lift cords are free to move through the cord lock. The cord lock is always in a locked position whenever neither the lift cords are being pulled to raise the blind nor the release cord is being pulled to lower the blind.