Web tension control

Claim 2

In a web transfer apparatus including means for rotatably supporting a supply spool and means for pulling a continuous web from the supply spool; the improved web tension control comprising: a stationary frictional drag means extending radially across and positioned in frictional engagement with all the edges of at least one side of the web material positioned on the supply spool, said frictional drag means being of a shape having at least a substantial portion thereof which decreases in width between its defining boundaries as measured in a circumferential direction of the supply spool as the drag means progresses outwardly from the center of the supply spool to effect a substantially uniform tension in said web material during its transfer, the boundaries of said decreasing portion being defined by two curves converging toward each other with the angle between the two curves varying inversely proportional to the square of the value of the radius from the center of the supply spool.

Claim 3

Apparatus according to claim 1 wherein said frictional drag means is formed of a fiberous material.

Claim 4

Apparatus according to claim 1 wherein said frictional drag means is formed of a felted material.

Claim 5

Apparatus according to claim 1 wherein said frictional drag means is formed of a polyester foam material.

Claim 6

In a serial printer having a platen, a laterally movable carrier for traversing a printing line, printhead means supported on said carrier for impacting with said platen to print characters, and ink ribbon transfer means supported on said carrier for delivering ink ribbon past said printhead means, wherein said transfer means includes means for rotatably supporting a supply spool, means for guiding and moving said ribbon between said printhead means and said platen; the improved ribbon tension control comprising: a stationary frictional drag means extending radially across and positioned in frictional engagement with all the edges of at least one side of the ink ribbon positioned on the supply spool, said frictional drag means being of a shape having at least a substantial portion thereof which decreases in width between its defining boundaries as measured in a circumferential direction of the supply spool as the drag means progresses outwardly from the center of the supply spool to effect a substantially uniform tension in said ink ribbon during its transfer, the boundaries of said decreasing portion being defined by two curves converging toward each other with the angle between the two curves varying inversely proportional to the square of the value of the radius from the center of the supply spool.

Claim 7

In a serial printer having a platen, a laterally movable carrier for traversing a printing line, printhead means supported on said carrier for impacting with said platen to print characters, and ink ribbon transfer means supported on said carrier for delivering ink ribbon past said printhead means, wherein said transfer means includes means for rotatably supporting a supply spool, means for guiding and moving said ribbon between said printhead means and said platen; the improved ribbon tension control comprising: a stationary frictional drag means extending radially across and positioned in frictional engagement with all the edges of at least one side of the ink ribbon positioned on the supply spool, said frictional drag means being of a shape having at least a substantial portion thereof which decreases in width between its defining boundaries as measured in a circumferential direction of the supply spool as the drag means progresses outwardly from the center of the supply spool to effect a substantially uniform tension in said ink ribbon during its transfer, the boundaries of said decreasing portion being defined by two curves converging toward each other with the angle between the two curves varying inversely proportional to the square of the value of the radius from the center of the supply spool.

Claim 8

Apparatus according to claim 5 wherein said frictional drag means is formed of a fiberous material.

Claim 9

Apparatus according to claim 5 wherein said frictional drag means is formed of a felted material.

Claim 10

Apparatus according to claim 5 wherein said frictional drag means is formed of a polyester foam material.