Abstract: A self-centering pressure roller for a high speed paper feed mechanism. The assembly includes two rollers each having an undercut central portion disposed for rotation on parallel axles. The roller axles are supported on a bracket movable in four degrees of freedom. The rollers are urged toward a platen to provide pressure on a paper sheet or web disposed between the rollers and the platen. The geometry of the roller assembly and the platen is chosen so that the reaction force caused by roller contact with the paper sheet or web causes the downstream pressure roller to exert more force on the sheet or web than the other roller thereby preventing bunching of paper between the rollers. The pressure roller assembly is self-aligning thereby preventing skew of paper fed through the assembly in either direction. The assembly can be easily manufactured without special alignment and is adaptable to accommodate many different paper widths.

Abstract: A combined mechanism for impacting a print member and advancing a printing ribbon of a high speed printer wherein an electromagnet, located near and on a yoke mechanism containing the print stem shaft of the print head, operate together with a linkage mechanism which is attached to the yoke mechanism, to impact the print head upon a platen and advance a printing ribbon one increment, the linking mechanism including several linking members and a stop which allows free movement to a first linking member and a cable which during energization is drawn taut but goes slack during de-energization and remains slack after the print head impacts and rebounds to a neutral position.

Abstract: A pair of electromagnets, each including pole faces separated by an air gap, cooperate with a permanent bar magnet, the ends of which extend into the electromagnet air gaps. Polarization of the electromagnets causes the bar magnet to shift into four possible positions thereby shifting a coupled print head to bring one of its four type bands into printing position.