Technique for precise color-to-color registration in thermal printers

Abstract

There is disclosed a method for providing precise color-to-color registration of color dots in a multicolor proof with a thermal printer comprising a CPU and Printer Controller, a Motion Controller, a writing drum, and a writing head coupled to a translation means. Using the disclosed method, a proof and a dye donor member with a predetermined dye color thereon are mounted on the writing drum. The writing head is then moved to a predetermined start position defined by a sensor at a predetermined position along the translation means which has its optical path blocked by the writing head. The writing head is then moved forward to a predetermined home position which is defined by a next subsequent pulse from a multi-pulse radial position-indicating encoder coupled to the translation means occurring after the writing head leaves the start position. In sequence, the writing drum and then the translation means are accelerated with a separate predetermined substantially constant acceleration until a separate predetermined velocity is obtained. After the predetermined velocity of the translation means is obtained, the printing of color dots on the proof is started upon the receipt of a next subsequent pulse from a multi-pulse radial position-indicating encoder coupled to the writing drum.