Abstract: A charge-removing device intended to eliminate electrostatic charge from a thin dielectric strip, and in particular a rolled dielectric film. The device comprises at least two electrically conductive rolls (4,5) forming electrodes which are subjected to a potential difference by a low frequency high tension source. These rolls are parallel and come into transverse contact at the same time with respective faces of a thin strip dielectric (1) passing therebetween. The invention is applicable, in particular, to electrostatic type printers.

Abstract: An electrostatic print head for creating a latent image on a dielectric recording medium (1) in order to enable said image to be subsequently transferred to a final medium (generally ordinary paper) after development by inking. The print head comprises a conventional multitude of electrodes (E) and associated conterelectrodes (CE) disposed in parallel rows for progressively building up an electrostatic latent image on the moving dielectric medium (1), and includes an additional rotary coupling electrode (EC) which is raised to a direct potential whose average voltage is of the same polarity as the high voltage control pulses applied to the counterelectrodes, which pulses are themselves of opposite polarity to the pulses applied to said electrodes. The coupling electrodes (EC) is pressed against the recording dielectric medium level with the electrodes and the counterelectrodes, and against the opposite side of the medium relative to said electrodes and counterelectrodes.

Abstract: An electrostatic printer uses a dielectric film (10) as an intermediate recording medium for an electrostatic latent image which is to be printed on a final recording medium (1) such as sheets of paper. The latent image is first developed by inking, and the inked image is then fixed on the final medium by pressure using a transfer unit having pressure rolls (11A, 11B) between which the intermediate medium and the final medium are passed while pressed against each other. Two portions of the same dielectric film are pressed against opposite faces of the final medium as it passes between the pressure rolls of the transfer unit with each portion being suitable for receiving an electrostatic latent image from a corresponding write head (8) with images being inked by corresponding inking devices (9), and with each inking device being associated with a corresponding different one of the rolls of the transfer unit.

Abstract: The invention relates to electrostatic print heads enabling an electrostatic latent image to be progressively built up on a moving medium (18) which may be constituted by special paper or by some other material, by discharging ions using a set of aligned electrodes (20) and a counterelectrode (1) disposed opposite said electrodes on the other side of the moving medium (18). The counterelectrode (1) is constituted by a cylindrical or semi-cylindrical resistive layer (7) covering connection conductors (C.sub.1 to C.sub.n+1) which are constituted by parallel rings or ring sectors sharing a common axis with the resistive layer and having cylindrical or semi-cylindrical resistive portions extending therebetween. The rings or ring sectors are individually connected to outlets from an electronic selective switching circuit (CEC) which is at least partially housed within the concave portion of said counterelectrode (1).

Abstract: A print head for direct or indirect electrostatic printing comprises at least one row (21) of electrodes disposed at a regular pitch and organized in n groups (G.sub.1 . . . G.sub.n) per row, together with a counter-electrode (1) constituted of a resistive material extending opposite the electrodes in the row with n+1 conductive tracks defining n resistances in series (R.sub.1 to R.sub.n) and constituting access connections (C.sub.1, C.sub.n+1) thereto for selecting different groups of electrodes.

Abstract: A flexible printed circuit (1) has conductive tracks (2) each having one end constituting an electrode in a linear arrangement of electrodes. The back of the printed circuit in the vicinity of said arrangement of electrodes is pressed against a convex structure and an insulating film (3) covers printed circuit away from the electrodes in order to ensure a desired gap between the electrodes and the surface of a recording medium (11) pressed against the head. The head is particularly applicable to forming an electrostatic latent image which is subsequently transferred to some other recording medium.

Abstract: An indirect electrostatic printer is characterized in that the intermediate medium in the form of a dielectric tape (1) is mounted in an open loop defined by a supply reel (2), an auxiliary roller (4) over which its path doubles back and a take up reel (3), and in that said auxiliary roller (4) and an associated pressure roller (14) define a combined station (7) for simultaneously transferring and fixing the image on the final medium which is in the form of individual sheets (8), and said auxiliary roller and said pressure roller constituting, together with said tape (1), means for conveying the sheets to a copy delivery station (15).