Reversed Helix Matrix Printer
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Both the bar helix and the dot drum helix printers suffer from ghost printing due to the hammer blade pushing the ribbon and the paper into contact with an adjacent helix. This article describes a solution to this problem. The bar helix and the dot drum helix are back printers. The element which forms the dot is behind the paper, and the hammer blade drives both the paper and ribbon onto the print element which is mounted on a rotating drum, as shown relative to a dot drum helix printer in Fig. 1. Both the bar helix and the dot drum helix suffer from ghost printing, i.e., light print dots appear where not wanted. A major cause of the ghost printing is due to the twisting of the hammer blade. When the hammer blade strikes the dots or the bar at one end of the blade, the other end of the blade is twisted towards the paper.