Electrostatic copier development monitor - capacitatively coupled charge detector detects charge on surface and doses toner accordingly

摘要

A development monitor for an electrostatic copier, in which the charge on the image is scanned to generate a signal proportional to the charge which is compared with a predetermined standard signal to determine the amount of toner material to be applied to the surface; the scanning may be effected by a coated scanning electrode coupled capacitatively with the photoconductive surface to induce a voltage which serves as the control signal. The amplitude of an induced voltage is metered, whilst the R.C. time constant of the coil is between 0, 1 and 10 sec.