CIRCUIT FOR CONTROLLING DENSITY OF PRINTING IN ELECTROPHOTOGRAPHIC PRINTER

PROBLEM TO BE SOLVED: To provide a circuit for controlling density of printing in an electrophotographic printer which can omit trial printing under unappropriate density of printing by automatizing to control the appropriate density of printing and neglecting which has been conventionality done by an operator. SOLUTION: This circuit for controlling density of printing in an electrophotographic printer is provided with a page memory 1 for storing image data and a parallel-series convertor for converting the image data of the page memory 1 to serial data. In addition, a counter 3 which uses output of this papallel-series convertor 2 as an input and operates the mean value of lengths of continuous black picture elements, a counter 4 which uses output of this papallel-series convertor 2 as an input and operates the mean value of lengths of continuous white picture elements and a circuit 5 for generating development bias which determines an appropriate density of image from the means value of the lengths of the black picture elements and the means value of the lengths of the white picture elements and sets an output are provided.