Automatic child-resistant sliding door lock

A magnetically actuated safety lock device provides automatic locking capability to doors such as sliding glass patio doors and prevents unsupervised opening of the door by young children, thereby barring their access to dangerous environments. When the sliding door is closed, it is automatically locked. The lock device is installed in a position high upon the sliding door to prevent actuation by young children and requires no permanent modification to the door on which it is installed. The lock device consists of a locking assembly and a magnetic key. The locking assembly includes a magnetized latch assembly and a mounting bracket. The latch is held in the locked position by gravity and is only rotated into the unlocked position through the application of hand pressure or the repulsive force of the magnetic key. The doors can be unlocked from both inside and outside the door. Upon removal of either the magnetic force or hand pressure, the latch rotates back into the locked position. The latch is designed with an angled surface on one side such that as the user closes the door behind him, the door can close normally. This angled surface in the latch allows the door to slide along its track in the closing direction and, as the door edge touches the latch at the angled surface, the latch is rotated by the door into the unlocked position. Once the frame of the door slides completely past the latch, the latch rotates back into the locked position.