Double-door safety access port for automated tape library

A method for controlling access to a cartridge retainer mechanism positioned within an access opening in an automated cartridge library housing for allowing insertion and removal of cartridges from the library, the library including an inner door mounted adjacent the access opening on the inside of library housing, and an outer door mounted adjacent the access opening on the outside of the library housing, said method comprising:

• selectively operating a motorized drive to move the inner door to either an open position which allows a robotic mechanism within the library housing access to the cartridge retainer mechanism, or a closed position which provides a barrier between the access opening and the inside of the library housing;
• preventing movement of the inner door by locking the motorized drive in response to an external force applied thereto;
• latching the outer door in a closed position when the inner door is not in a closed position to prevent the outer door from being moved into an open position;
• and
• unlatching the outer door only when the inner door is in the closed position.