Abstract: A paper transport mechanism for data printers having powered platens includes a marginal perforation paper transport tractor upstream of the platen and a means for supplying unmargined perforated paper independent of the tractor to the platen, the platen having opposed pinch rollers, and means for adjusting the pinch force of the pinch rollers to accommodate either unperforated platen driven paper or perforated tractor driven paper.

Abstract: The paper transport shaft of a paper feed mechanism is movably mounted on an arm of a frame-supported spring wire lever. Another arm of the spring wire lever is pivotably mounted and may be set to flex the body of the spring wire lever through a pivot lever. Depending on the pivoting of the pivot lever the contact pressure between a paper pressure roller mounted on the paper transport shaft and a platen is varied. Selectively, the paper transport shaft can be pivoted away from the platen to allow adjustment of the paper inserted in the paper feed mechanism.

Abstract: A typewriter ribbon cassette contains a feed spool and a take-up spool which are both displaceably arranged in guide slots in the cassette housing. The guide slot for the feed spool leads to a control corner edge opening into an enlarged recess. The feed spool is biased with a spring force towards the control edge of the slot during unwinding of the ribbon roll, so that, when the feed spool has overrun the control edge, the spool is pivoted into a switching position which can be detected by a monitoring device for signalling an end of tape state of the ribbon roll. The hub of the feed spool is provided with a guide pilot for sliding along the guide slot which has a cornered plan profile for holding the hub in a straight line path along the slot until after the control edge is overrun.