Patent ID: 6860129

Claim:
A security classroom function lock mechanism for mounting in a door comprising: an inner lock mechanism operable by an inner lock cylinder and corresponding inner key to change the inner lock mechanism between an unlocked state and a locked state; an outer lock mechanism operable by an outer lock cylinder and corresponding outer key to change the outer lock mechanism between an unlocked state and a locked state, the state of the inner and outer lock mechanisms being independent of each other; a latch mechanism including a latch bolt operable by inner and outer handles for movement between an extended position to latch the door and a retracted position to open the door; and a locking piece movable between a locked position and an unlocked position, the locking piece preventing the outer handle from moving the latch bolt to the retracted position when the locking piece is in the locked position, the locking piece being driven to the locked position from the unlocked position when either the inner lock mechanism or the outer lock mechanism is changed to the locked state and the locking piece being driven to the unlocked position when both the inner and outer lock mechanisms are changed to the unlocked state, the locking piece not being driven to the unlocked position from the locked position when the outer lock mechanism is changed to the unlocked state and the inner lock mechanism remains in the locked state.