A refill unit that includes a case, a door, a locking member and an unlocking member. The locking member slides between a protruded position and a retracted position and is engageable with the case at an intermediate position between the protruded position and the retracted position to lock the door...http://www.google.de/patents/US7607769?utm_source=gb-gplus-sharePatent US7607769 - Refill unit
