Abstract: Control over the electrostatographic process is provided by adjusting the toner charge-to-mass ratio in response to changes in toner contrast. An electrostatographic reproduction machine produces a signal having a value characteristic of the toned density of the developed image. Using the signal, the charge-to-mass ratio of the toner is adjusted. In a preferred embodiment, the signal is produced by comparing the toned density of the developed image to a reference value, and charge-to-mass is adjusted by directing an ion cloud over the toner particles.

Abstract: Apparatus is disclosed for controlling the charge-to-mass ratio of developed electrostatic images. An electrostatographic reproduction machine for developing an electrostatic latent image with charge toner particles produces a control signal characteristic of the ratio of toner partical electrostatic charge to the toner particle mass, and the charge-to-mass ratio is adjusted in response to the control signal. The control signal is produced by comparing the ratio of toner particle electrostatic charge to the toner particle mass of a toned test patch. The ratio is adjusted by means of ions directed to the toner particles. The ion source may be capable of producing positive and negative ions, and may be a corona charger.