Improvements in or relating to electrostatographic copying and duplicating

摘要

An electrostatographic duplicator in which an original document is duplicated by redeveloping a previously developed and fixed latent image has a rotatory drum 4 for supporting a sheet of electrostatographic recording material releasably clamped thereon. A supply spool 1 carries electrophotographic recording material in web form, and rollers 2 advance the recording material towards the drum 4, after which guillotine 3 cuts an individual sheet of predetermined length from the advancing web. The individual sheet is directed by rollers 2 onto the support member and clamped thereon. A corona charging unit 12 electrically charges the recording material on the support member, an imaging station 11, 25 projects a light image of the original document onto the recording material, a development station 7 applies an insulating toner to an electrostatic latent image on the recording material and a master fixing unit 14 fixes the developed toner image onto the sheet of recording material supported on the drum 4. In duplicating cycles means 16, 17 feeds copy sheets serially towards the support member, a transfer station is located so that copy sheets pass between an electrically charged transfer member 9 and the recording material on the drum 4 so that an unfixed toner image transfers onto a copy sheet. The copy sheets pass to a copy sheet fixing device 5 and the recording material travels past a cleaning unit 20 before it is re-charged at corona unit 12 and flood exposed at a station 20 in the next duplicating cycle, control means responsive to a start button and a counter records the number of duplicated copies required and controls the operation of all the aforesaid devices so that (I) in a master preparation cycle a sheet of recording material is cut from the material on the supply spool 1 and clamped onto the drum 4 after which a fixed toner image is formed on the master by driving the drum 4 at a first speed, electrically charging the recording material, forming a latent image of the original document thereon, developing 7 the latent image with toner and radiant heat fusing the developed toner image onto the recording material, (11) in subsequent duplicating cycles the drum 4 is driven at a second speed higher than the first speed and cyclically the drum is cleaned (20), electrically charged (12), uniformly illuminated (15) and redeveloped with toner (7) and the resulting toner image is transferred onto copy sheets and fixed thereon, and (III) on completion of duplication the used sheet of recording material is ejected from the support member.