Abstract: An impact printer has a print band moving longitudinally around pulleys with one side of the band moving in contact along a rigid platen and the other side having engraved characters presented along a print line of a print medium (e.g. paper and ink ribbon). The leading edge of platen is squared off (e.g. sharp) to scrape contamination off the band. A row of hammers impact the print medium against the band between the hammers and an impact surface of the platen. The impact surface of the platen contains multiple longitudinal grooves which start slightly back from the leading edge of the platen and which prevent increased friction force between the band and platen from occurring as the band wears the platen impact surface smooth.

Abstract: A platen for a line printer has a polymer wear resistant strip on a base support. To reduce frictional drag on the band which is in sliding engagement with the wear strip, the leading edge of the strip is slanted against the direction of motion of the band and is provided with grooves that run perpendicular with the leading edge.

Abstract: A document feed mechanism for a copier machine incorporating an automatic document feed (ADF) with a semi-automatic document feed (SADF) and enabling the SADF to interrupt the ADF. The ADF tray upon which a stack of documents to be copied is placed is situated directly above the viewing station. A wave generator (shingler) paper feed means fans out the topmost sheets on the stack and up a ramp until the topmost sheet enters closed nip rollers. The nip rollers, together with aligner rollers and a drive belt, move the sheet around a substantially 180.degree. bend and onto the viewing station. Second sheet feeds are prevented by a restraint pad positioned between the nip rollers and the exit of the ramp, the top of the restraint pad being above the nip of the nip rollers so that the topmost sheet presses a second sheet downwardly into the restraint pad. The SADF feeds sheets onto the viewing station using the aligner rolls and the drive belt.

Abstract: Method and apparatus for automatically producing a duplexed copy in a document copier machine wherein the leading edge of the rectangular copy sheet is maintained during both passes through the machine and wherein both simplexed and duplexed copies may be collated. This method and apparatus is especially useful when the leading edge is the narrow dimension of the rectangular copy paper.