Automatically regulating magnetic drum for better printing - using magnetic pick=up to sense magnetic image strength on drum and compensate for variations

摘要

A magnetic printing mechanism uses a magnetic printing head (MK) to create a magnetic image on a rotating drum which transfers the image to the paper (P). Printing quality can deteriorate because of variations in drum magnetisation caused by changes in temp. or in the print-head gap (S). A magnetic read head (L) can sense the strength of the pattern on the drum. A feedback circuit (R) can compare this to a target value (SW) and adjust the printing-head current accordingly. ADVANTAGE - Consistent high quality prints.