Apparatus for charging photo-electrostatic semiconductor layers

Claim 1

An electrophotographic recording device comprising: (a) means for feeding along a predetermined path paper having a photoconductive semiconductor layer; (b) means for projecting a light image on said photoconductive semiconductor layer to form a latent image at a first station along said path; and (c) corona discharge means for subjecting said photoconductive semiconductor layer including said latent image to a corona discharge field at a second station downstream of said first station along said path to form a latent charge image; (d) said corona discharge means comprising a corona electrode, a voltage transformer for supplying current to said corona electrode, a casing enclosing said electrode, said casing comprising a first cylindrical tube having a slit opening in one side thereof for transmitting corona discharge from said electrode to said photoconductive semiconductor layer including said latent image and a second tube telescopically nested over said first tube and including a further slit opening therein, a housing enclosing said casing and electrode, said housing having an opening adjacent said paper for directing said corona discharge from said electrode to said photoconductive semiconductor layer including said latent image, and electrical means and mechanical means for varying the intensity of the corona discharge at the surface of said photoconductive semiconductor layer including said latent image, said mechanical means comprising means to rotate said first and second tubes relative to each other to vary the width of an opening formed by said slits through which said corona discharge is emitted; (e) whereby the amount of charge applied to the exposed portion of said photoconductive semiconductor layer may be controlled.