Apparatus for maintaining a predetermined quantity of an elongated medium at a predetermined zone

Claim 1

APPARATUS FOR MAINTAINING A PREDETERMINED QUANTITY OF AN ELONGATED MEDIUM AT A PREDETERMINED ZONE COMPRISING DRIVING MEANS FOR DRIVING SAID MEDIUM INTO OR OUT OF A PREDETERMINED ZONE, SUPPLY MEANS FOR FEEDING SAID MEDIUM TO OR WITHDRAWING SAID MEDIUM FROM SAID ZONE SELECTING MEANS FOR SELECTIVELY OPERATING SAID DRIVING MEANS TO MOVE SAID MEDIUM INTO OR OUT OF SAID ZONE AND TO CONDITION SAID SUPPLY MEANS TO WITHDRAW SAID MEDIUM FROM OR FEED SAID MEDIOUM TO SAID ZONE, SENSING MEANS RESPONSIVE TO THE QUANTITY OF SAID MEDIUM IN SAID ZONE, AND CONTROL MEANS FOR SAID SUPPLY MEANS RESPONSIVE TO SAID SELECTING MEANS AND SAID SENSING MEANS TO INTITIATE OPERATION OF SAID SUPPLY MEANS IN A SENSE TO REMOVE MEDIUM FROM SAID ZONE WHEN THE AMOUNT OF MEDIUM THEREIN EXCEEDS A PREDETERMINED QUANTITY AND WHEN SAID DRIVING MEANS IS OPERATIVE TO MOVE MEDIUM INTO SAID ZONE, AND TO INITIATE OPERATION OF SAID SUPPLY MEANS IN A SENSE TO FEED MEDIUM TO SAID ZONE WHEN THE AMOUNT OF MEDIUM THEREIN IS LESS THAN A PREDETERMINED QUANTITY AND WHEN SAID DRIVING MEANS IS OPERATIVE TO MOVE MEDIUM OUT OF SAID ZONE, AND MEANS, OPERATIVE ONLY AFTER OPERATION OF SAID SUPPLY MEANS IN A PARTICULAR SENSE HAS BEEN INITIATED IN RESPONSE TO BOTH SAID SELECTING MEANS AND SAID SENSING MEANS, FOR MAINTAINING SUCH OPERATION IN RESPONSE TO SAID SENSING MEANS BUT INDEPENDENTLY OF SAID SELECTING MEANS.