Auxiliary control device for managing printing in a thermal printer

Abstract

The present invention provides a dot history compensation system for varying the drive current to the points of a thermal print head in response to the printing history of the points. One or two previous print lines may be examined. In addition, the history of points adjacent to a selected point may be used to compute a head drive signal. The inventive system is implemented in an auxiliary control device within a thermal printer. In addition, an end point compensation system is provided to ensure that end points of a thermal print head receive equivalent amounts of energy to central points, even when a large number of points may be simultaneously fired. The inventive system is adapted for operation with both single color and multiple color thermal printers. The auxiliary control device also manages paper movement functions, thus freeing the main microprocessor for communications and other duties within the printer. Specifically, the auxiliary control device provides a dot history system, both row-to-row and adjacent dots, for use in either a single color or multiple color thermal printer.

Dependencies are inferred from the claim text.