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 .