Abstract: A thermal printer (10) has a thermal transfer medium (28) fed past a thermal printhead (21) at a substantially constant velocity by a feed roll (82) engaging the thermal transfer medium just prior to the printhead to maintain a portion of the thermal transfer medium between the printhead and the feed roll relatively stiff. The feed roll is mounted on a cartridge (30) having the thermal transfer medium supplied therefrom. A drag brake (70) is disposed in the feed path of the thermal transfer medium prior to the feed roll to cause a substantially constant premetering tension to be applied to the thermal transfer medium irrespective of the coefficient of friction between the drag brake and the thermal transfer medium. A carrier (14), which supports the printhead and a feed roll driver (90), is driven separately from the feed roll driver so that various ratios between the velocities of the thermal transfer medium and the carrier are obtained to produce various print qualities.

Abstract: Disclosed is a spring operating beyond the elastic limit of the material of which it is constructed, the spring including a length of resilient material having terminal end portions and a central body portion, one of the terminal end portions being adapted for connection to a first member. A convoluted portion of the resilient material has a central axis substantially perpendicular to the body portion and is adapted for connection to a second member, at least the convoluted portion being dimensioned so that upon separation of the first and second members due to a predetermined load, the convoluted portion uncoils and is stressed beyond the yield point of the material so that a substantially constant load placed on the convoluted portion by member separation effects further uncoiling of the convoluted portion.

Abstract: In a ribbon cartridge for retaining and supporting a ribbon in a typewriter, the cartridge comprising spaced apart top and bottom walls and a sidewall joining the top and bottom walls adjacent the periphery thereof to form a chamber. The sidewall of the cartridge is discontinuous at predetermined locations to form at least entrance and exit apertures for the ribbon, and at least a ribbon take up spool is provided in the chamber in communication with the ribbon entrance aperture to take up used ribbon passing through the entrance aperture.

Abstract: Disclosed is a ribbon tape cartridge assembly, the cartridges being adapted for mating in superimposed overlapping relation, bottom to bottom to form the assembly. Slots in tabs which project from the plane of one of the bottom surfaces of one of the cartridges coact with fins on the other of the cartridges, the fins movable into the slot for an interference fit with at least a portion of the tab. Shoulders on each of the cartridges also coact for limiting relative movement of the cartridges in a first direction with respect to each other. One of the cartridges is provided with a camming surface and a cam follower is provided the other of the cartridges, the cam and cam follower being engageable to effect relative movement between the cartridges in the first direction until the shoulders abutt one another inhibiting further relative motion.