Printing in register on sheets

Abstract

This invention is concerned with the high speed printing of a line of text on a sheet in very accurate registration with an edge of the sheet or another feature (for example an existing print line) on the sheet. The sheet is fed without preregistration on to a track (10, FIG. 1) which passes the printing station (20). A detector (16) adjacent the track senses the arrival of the edge or some other feature of the sheet and a printing control means (14) responsive to the detector signal initiates the firing of the printing hammer (22) when the print line reaches the printing station, a registered operation being thereby effected without stopping the sheet. The detector signal may start the operation of a counter (70, FIG. 4) and a firing signal is sent to the hammer control circuit (100, 102, 104) when the count reaches a value dependent on the distance between the detector and the point at which the printing operation takes place and (unless the new print is to be in alignment with a detected print line) also dependent on the distance on the sheet between the edge or feature detected and the position at which the new print is to appear.