corona discharge r is caused in the aperture portion 5 as shown in fig6 by the potential difference between the driving electrode 3 and the control electrode 4 selectively supplied with a pulsed voltage and ions i generated by this creeping corona discharge r are accelerated or absorbed by an electric field selectively formed between the control electrode 4 and the screen electrode 8 so that an ion current s is controlled and derived from the aperture portion 10 of the screen electrode 8 thereby forming in correspondence to a picture signal controlling pulse source 18 an electrostatic latent image on the dielectric drum 11 at that time the insulating member 14 is provided on the ion derivation side of the screen electrode 8 and the insulating member 14 has the aperture portions 15 for controlling ions formed in the positions corresponding to the aperture portions 10 of the screen electrode 8 therefore as shown in fig6 the derivation direction of the ion current s selectively derived from the aperture portion 10 of the screen electrode 8 is restricted by the inner wall of the aperture portion 15 of the insulating member 14 so that the ion current s is derived without expanding therefore the ion current s reaches the surface of the dielectric drum 11 in the form of a thin beam corresponding to the diameter of the aperture portion 10 of the screen electrode 8 without expanding so that a high resolution recording dot d accurately corresponding to the aperture portion 10 of the screen electrode 8 is formed efficiently on the surface of the dielectric drum 11 as shown in fig7 thus the ion current s derived from the aperture portion 10 of the screen electrode 8 is controlled by the aperture portion 15 provided.