Form overlay type printing apparatus

Abstract

A form overlay type document printing apparatus includes a format memory for storing form data, a repetition data memory for storing common data to be printed on successive documents, and a variable data buffer for storing data which is unique to such document. A printing pattern generator converts the repetition data and unique data to corresponding printing signals and a form pattern generator generates printing signals for reproducing a selected form. The printing signals corresponding to the form data and the repetition data are combined and repetitively supplied to an output buffer as long as there is no change in the form or the repetition data. The printing signals corresponding to the unique data are also supplied to the output buffer. The contents of the output buffer are supplied to a head driver which controls a printing head to generate the desired printed output. In this manner, only the unique data and data arising from a change in the form or the repetition data need be transmitted from a host computer to the printing apparatus.