Tape tensioning apparatus particularly useful in printing apparatus

Abstract

A tape tensioning apparatus particularly useful in regulating the tension in a tape such as an elongated strip of printer ribbon stock used in printing apparatus such as mechanical impact printers. A stock guide is supported for rotation on a base, the stock guide having an arm from which extends a roller. An inclined surface on the stock guide rests on a complementary inclined surface on the base so that the stock guide moves toward the base as the stock guide is rotated in a predetermined direction from a predetermined angular position, with a spring yieldably biasing the stock guide to its predetermined angular position. A spool of print or ribbon stock is mounted on a reel, itself supported for rotation with respect to the base, with the stock passing around the roller on the stock guide after exiting from the spool thereof and with the reel resting on and rotatable with a reel support disc which is constrained from moving more than a predetermined distance above the base. A compressible, resilient O-ring is located between the reel support disc and the stock guide and is fully compressed therebetween when the stock guide is in its predetermined angular position so as to inhibit rotation of the reel support disc and the reel wit respect to the stock guide. As a force is exerted by the printing apparatus on the stock to draw the stock from the spool thereof, the stock guide rotates away from its predetermined angular position and moves toward the base to progressively decompress the O-ring to eventually permit the reel support disc and the reel to rotate with respect to the stock guide. The stock guide and base are also provided with complementary surfaces adjoining the inclined surfaces thereof which define maximum and minimum elevations of the stock guide above the base which may be used to detect abnormally low tension and abnormally high tension conditions in the print or ribbon stock.