Process for electrostatic printing and apparatus therefor

The electrostatic printing process of claim 17, including repeating said steps of forming, developing and transferring.

In an electrostatic printing process which includes the repeated steps of developing an electrostatic latent image on a smooth-surfaced electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, to thereby form a visible image, and transferring the developed visible image onto a support therefor, the improvement comprising enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of said developer to adhere thereto and create undesired fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.

In an electrostatic printing process which includes the repeated steps of developing an electrostatic latent image on a smooth-surfaced electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, to thereby form a visible image, transferring the developed visible image onto a support therefor, and then cleaning the electrostatic printing master after said transfer, the improvement comprising enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of said developer to adhere thereto and create undesired fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.

In an electrostatic printing process which includes the repeated steps of transferring a developed visible image formed on a smooth-surfaced electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, onto a support therefor, the improvement comprising enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of said developer to adhere thereto and create undeisred fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.

In an electrostatic printing process which includes the steps of forming an electrostatic latent image on a smooth-surfaced electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, transferring said electrostatic latent image onto a support therefor, and then developing the transferred electrostatic latent image on said support to form a visible image, the improvement comprising enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of said developer to adhere thereto and create undesired fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.

In an electrostatic printing process which includes the steps of forming an electrostatic latent image on a smooth-surfaed electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, transferring the electrostatic latent image onto a support therefor, developing the transferred electrostatic latent image on said support to form a visible image, and then transferring the developed visible image onto another support, the improvement comprising enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of said developer to adhere thereto and create undesired fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.

An apparatus for electrostatic printing which comprises means for forming an electrostatic latent image on a smooth-surfaced electrostatic printing master, stable towards exposure to light or maintenance in the dark, having a layer which comprises an insulating medium having an electric resistance sufficient to retain an electrostatic charge and a conductive silver image in said insulating medium, means for developing said latent image to form a visible image, means for transferring the developed visible image onto a support therefor, and means for heating and enhancing the electrical conductivity of said silver image by heating said master at least once during said printing process sufficient to reduce the tendency of the developer to adhere thereto and create undesired fog, whereby said enhanced conductivity is imparted to said silver image portion through at least about 10 cycles of printing.