Electrostatic facsimile printer

Claim 1

An electrostatic facsimile printer comprising: a bed plate having a slot therein and a non-conducting surface for contacting a dielectric surface record sheet as it passes over said plate; drive roll means for transporting record sheets across said bed plate and said slot and including a conductive electrode opposed to and extending along the length of said slot on one side of said bed plate; a pair of spaced pulleys mounted for rotation on the other side of said bed plate with an endless belt thereon movable along the length of said slot as said pulleys rotate; at least one conductive stylus mounted on said belt and driven thereby in guided relation to said bed plate to traverse said slot with substantially rectilinear motion to define with said conductive electrode a moving elemental area electrostatic charge concentration electrode system; means for rotating said drive roll means and said spaced pulleys in timed relation and in synchronism with a remote transmitter respectively to advance across said slot a record sheet inserted in said drive roll means and to scan said stylus repeatedly along said slot thereby scanning line by line the area of said record sheet with approximately 100 line per inch resolution; means coupling facsimile signals received from said remote transmitter to apply corresponding charge producing voltage across said electrode system for forming line by line an invisible charge image on the dielectric surface of a record sheet between said stylus and said conductive electrode, said invisible charge image forming on successive scans a synthesized invisible charge image corresponding to the image on said original document with a line resolution of approximately 100 lines per inch; an electrostatic developing station positioned to receive said record sheet as it emerges from said bed plate; and means for directing said record sheet with said synthesized charge image intact to said electrostatic developing station for producing a permanent visible image on said dielectric surface; said stylus comprising a metal flaT leaf spring electrode member mounted on said belt to project with a trailing angle toward said dielectric surface of said record sheet, and a wearresistant, low-friction dielectric material covering the projecting end edge of said metal electrode member except for a central portion where the metal is exposed, said dielectric material being positioned to contact said dielectric surface when said electrode system is conditioned to produce charge images and spacing said exposed portion of said metal electrode member from said dielectric surface by the thickness of said dielectric material, whereby the end of said stylus in contact with said dielectric surface of said record sheet is resistant to wear, friction between said stylus end and said record sheet is low and the electrode member of said stylus is spaced from said record sheet.