Abstract: A door lock for use particularly with sliding patio doors. The lock assembly includes a rotary actuator (door knob) connected to a shaft which drives a crank connected, in turn, to one or more spring-biased bolt rods and operable through the crank to shift the bolt rod to its spring-biased, door-locking position. Stops are positioned to stop the movement of the crank in the locking and unlocking positions of the bolt rod, respectively. Rotary interengaging means such as a pair of meshing gears releasably connect the crank to the shaft assembly. A latch maintains the spring-biased bolt rod releasably in its door-locking position when the gears are meshed. A trip disengages the gear when the bolt rod is in its spring-biased, door-locking position, thereby actuating automatic unlocking of the door.