Unidirectional control mechanism for a sliding closure member

Claim 1

IN A SLIDING CLOSURE INCLUDING A SUPPORT PROVIDING AN OPENING AND A SASH SLIDABLY FITTED IN THE SUPPORT FOR MOVEMENT IN OPPOSITE DIRECTIONS ALONG A PREDETERMINED PATH BETWEEN OPEN AND CLOSED POSITIONS IN THE OPENING, A MECHANISM FOR LIMITING OPENING OF THE SASH COMPRISING A FIRST RATCHET MEMBER BORNE BY THE SUPPORT; A SECOND RATCHET MEMBER MOUNTED ON THE SASH AND MOVABLE BETWEEN A LOCKING POSITION ENGAGING THE FIRST RATCHET MEMBER TO PRECLUDE OPENING OF THE SASH BEYOND A PREDETERMINED OPEN POSITION, AND A POSITION RETRACTED THEREFROM PERMITTING UNRESTRICTED SLIDING OF THE SASH INTO FULLY OPEN POSITION, SAID SECOND RATCHET MEMBER BEING YIELDABLY URGED INTO LOCKING POSITION; CONTROL MEANS ENGAGEABLE WITH SAID SECOND RATCHET MEMBER AND OPERABLY ASSOCIATED WITH THE FIRST RATCHET MEMBER TO MOVE THE SECOND RATCHET MEMBER INTO RETRACTED POSITION ONLY WHEN THE SASH IS IN FULLY CLOSED POSITION; AND A LATCH RELEASABLY ENGAGEABLE WITH THE SECOND RATCHET MEMBER TO HOLD IT IN RETRACTED POSITION.