Electrographic-writing head having a preponderance of conductive portions engaging the recording medium

Claim 1

An electrostatic recorder for forming a charge image on the charge-retentive surface of a recording medium having a conductive backing, comprising the combination: a recording head having a bearing surface which engages the charge-retentive surface of the recording medium, a preponderance of the bearing surface formed by conductive material so as to minimize unwanted charge transfer between the recording head and the recording medium due to relative motion therebetween; a backup electrode positioned proximate to the recording head in electrical contact with the conductive backing of the recording medium for retaining the charge retentive surface of the recording medium in engagement with the bearing surface of the recording head; means for establishing relative movement of the recording medium between the recording head and the backup electrode; a plurality of writing electrodes mounted within the recording head the terminal surfaces of which are exposed along the bearing surface of the recording head; means for selectively activating the writing electrodes for establishing a writing discharge between the activated writing electrode and the backup electrode through the recording medium; and insulative means between the writing electrodes and the conductive material in the recording head, the insulative means having a thickness sufficient to avoid writing discharge between the conductive material and the writing electrodes.