Pre-Extracting Boundary Samples for SVM Based on Perpendicular Bisector Distance Method

A ribbon drive device comprising a rotatably supported drive roller, a rotatably supported idler roller and a device for biasing the idler roller against the drive roller to form a nip therebetween through which a ribbon is fed. The device for biasing the idler roller is positioned to apply a bias force to the idler roller at the longitudinal center thereof. The device for biasing comprises a straight piece of round or rectangular spring wire positioned in a groove formed in the periphery of the idler roller.