AUTOMATIC CONTRAST CONTROLLING DEVICE FOR PRINTER

摘要

PURPOSE: To automatically control contrast by comparing an estimated density signal with the function of an indication valve of a current and adjusting the operation parameter of a printer and determining the error signal related to the point applied by a printing head. CONSTITUTION: The activation signal synchronizing with the rotation of a drum 20 is received from a printing head controller 16 in a drive charge generator 12 and a charge carrier 22 is projected on the drum 20 to accumulate the latent charge image determined in relation to a point on the drum 20. The digital electrode control signal from the controller 16 is subjected to addition processing by an adder 40 and the quantity E[Q(t)] showing the charge accumulated on the drum 20 is formed. After the drum 20 is rotated by 1/4. toner is supplied toward the drum 20 from the toner roll 24 of a toner stocker 26. The signal E[Q(t)] from the adder 40 is delayed by 1/4 rotation to be inputted to a comparator 50 and compared with actual drum charge Q(t) to form an error signal e(t) and a printing head control parameter is corrected.