Ribbon cartridge with improved ribbon tensioning and locking

Claim 1

In a ribbon cartridge for use in a typewriter, printer, and the like, comprising a housing having an exit and an entrance mounted therein, a ribbon supply spool and a takeup spool, a length of ribbon mounted on said supply spool and extending therefrom along a predetermined path out of the exit of said housing and back into the entrance of said housing to said takeup spool and a ribbon driving assembly, said driving assembly being drivable incrementally to transfer said ribbon from said supply spool to said takeup spool, the improvement comprising: a spring member having a fixed end and a free end which member positioned adjacent to the predetermined path of the ribbon between the supply spool and the exit from the housing and which spring member is movable from a rest position wherein said spring member bears against the ribbon along a length thereof to captivate the ribbon and prevent the ribbon from moving toward the exit, to a range of energized positions wherein the ribbon passes around said spring member's free end and said spring member serves to tension the ribbon, said spring member being such that a normal drive force applied to the ribbon will move said spring member from its rest position to its energized position but an overrun of ribbon from the supply spool will result in the return of said spring member to the locked position and wherein said spring member is preformed to conform in its rest position to a fixed roller and a fixed post such that the ribbon is sandwiched between said member and said post.