METHOD AND APPARATUS FOR THE CONTROL OF GREY LEVEL

摘要

A method of and apparatus for controlling gray scale in the charge sensitive media of a matrix printer by using constant amplitude write pulses. Their use is intended to overcome registration problems caused by constant movement of the charge sensitive recording media during the actual print cycle. This control method and apparatus are implemented by varying, as a function of the desired intensity of one or more pixels to be printed, the effective write time and the number of constant amplitude pulses applied to any one or more of a plurality of print electrodes over a complete write cycle. The normal printer write cycle is divided into a number of subdivisions, that number being a function of the maximum permissible allowable error that can be perceived by a human eye. Further, the write pulse waveforms used are derived so that there is not more than one write cycle subdivision difference at either termination point of any intensity pixel printed therewith.