1,259,513. Electro-photographic apparatus. RANK XEROX Ltd. Jan 31, 1969[Feb.1, 1968], No. 5388/69. Heading G2H. Toner particles retained on an electrostatographic imaging surface after transfer of a developed image are removed by at least one cleaning blade assembly comprising at least one flexible cleaning blade having an angular imaging surface engaging edge and being mounted to permit the cleaning blade to align itself parallel to the imaging surface when engaged with the imaging surface, a dry solid lubricant being supplied to the imaging surface. In the embodiment shown in Fig. 14, the blade 390 with a rigid backing plate 352 is mounted within the jaws of a blade holder 354 pivotly mounted on a shaft 360, the shaft being permanently secured to a hinged member 362. The hinged member has an extension 388 which carries a roller cam follower 384 which engages with a cam 382 fixed to the cylindrical imaging surface 364 so as to disengage blade 390 from the imaging surface once per revolution of the drum. The ridge of toner particles accumulated by the blade is thus transported on the moving surface and removed by cascading developer in the developing apparatus. Any toner particles which gravitate away from the blade are collected in a trough (not shown). In place of the cam, the drum may have transverse grooves (52), Fig.2 (not shown) into which the ridge of toner particles is lodged by the action of the blade, the trailing edge of the groove being of such angle that it sweeps the leading edge of the blade. The toner particles are again collected in the developing apparatus. Several blades may be provided extending across the drum surface either as separate units, Fig. 16 (not shown) or combined as one unit, Fig.17 (not shown), or alternatively, Fig. 18, the blades 450, 452, 454 extend part way across the surface in a staggered array, grooves 464, 466, 468 of less extent than the blades being provided in the drum surface. In a further embodiment, Fig. 9 (not shown) the blade has a flexible metal backing and is supported in the manner of a windscreen wiper blade. The electro-photographic apparatus may be of the line-by-line type with a drum, or of the whole frame type using an endless belt. The solid, dry, lubricant may be mixed with the toner, or applied to the developer from a separate hopper. In the case of apparatus using an endless band, a lubricant powder cloud generator is described. Alternatively, the lubricant is dispersed throughout the photoconductive layer or suspended in a photo-conductive overcoating layer. Suitable lubricants are metal salts of fatty acids, examples being zinc, barium, lead, iron, nickel, cobalt, copper, strontrium, calcium, cadmium and magnesium stearate; zinc, manganese, iron, cobalt, copper, lead and magnesium oleate; zinc, cobalt, copper, magnesium, aluminium and calcium palminate; lead caprylate; lead caproate; zinc, cobalt and calcium linoleate; zinc and cadmium ricolinoleate; higher aliphatic acids such as stearic and palmific acid; and colloidal pyrogenic silica particles. The lubricant may be chosen to have the same as or a contrasting colour of the receiving sheet.
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