Constant force windup spring web threading system

In an automatic tape threading apparatus for moving a leading end portion of a tape coiled on a removable supply reel positioned on a tape transport through a circuitous tape path from a first position adjacent the supply reel to a second position at a take-up reel disposed at an opposite end of said circuitous tape path from said supply reel for subsequent co-rotation with said supply reel for transporting said tape therebetween along said circuitous tape path;

• including, in combination:
• channel guide means on said tape transport extending between said supply and take-up reels adjacent said circuitous tape path and having a geometric configuration similar to the configuration of the tape path such that any motions along said channel guide means are similar to motions along said circuitous tape path;
• a negator flexible self-coilable band-shaped spring movably disposed in said channel guide means for reciprocating motions between said supply and take-up reels and having one end affixed to said take-up reel and exhibiting a coilable force sufficient to move said tape from said first to said second position along said circuitous tape path;
• a negator spool affixed to a second end of said negator spring and movably disposed in said channel guide means for motions therealong between said supply and take-up reels and adapted to coilingly receive said negator spring and having a tape end engaging pin coaxially extending therefrom toward said circuitous tape path such that as said negator spring coils on the negator spool the tape moves from the first to the second position along said circuitous tape path under the urging of said negator spring;
• latch means movably mounted on said tape transport immediately adjacent said first position for movements between a negator spool latching position and a negator spool unlatching position whereby unlatching the latch means threads tape from said supply reel along said circuitous tape path from the supply spool that is attached to said tape-end engaging pin;
• means for rotating said supply reel for winding said tape thereon such that the tape is completely removed from said take-up reel;
• leader means affixed to the free end of said tape and movable along said circuitous tape path with said tape between said first and second positions and having tape-end engaging pin receiving means for removably receiving said tape-end engaging pin as said supply reel is placed on said tape transport at said first position;
• means interposed between said first position and said latch means for moving said latch means from said latching position to said unlatching position as said supply reel is placed in said first position and from said unlatching position to said latching position as said supply reel is removed from said first position such that said negator spool is latched at said first position whenever no supply spool is at said first position and unlatched for said reciprocating motions when a said supply spool is at said first position;
• and
• said leader means being arranged for carrying said tape engaging pin from said second to said first position as said tape is being wound on said supply reel as said leader means moves from said take-up reel to said supply reel whereby rewinding the tape from the take-up reel onto said supply reel uncoils said negator spring from said negator spool and moves the negator spool to said latch means for enabling threading a tape through said circuitous tape path.