Patent GB-951251-A (GB)
Title: Image reproduction
IPC: G03G15/30
Filed: 1960-03-09
Abstract: 951,251. Electrophotographic copying; image reproduction. RANK-XEROX Ltd. (Haloid Co.). March 9,1960, No. 8292/60. Headings G2A and G2H. A method of producing a recording of a stationary original, comprises the steps of optically scanning the stationary original so as to project, by rectilinearly moving a lens means, successive strip-like areas thereof on to a steadily moving light-sensitive recording surface in such manner that a substantially distortionless image of the original is formed and recorded with the aid of said surface, the projection paths at said surface of all the striplike areas having a common crosssection fixed in space. As shown electrophotographic copying apparatus employing said method comprises a drum 11 having a photoconductive layer thereon and rotating successively past an exposure station 12, a developing station 13, a regeneration station 14, a paper feed station 15, a transfer station 16, a cleaning station 17 and an exposure station 18. The exposure device comprises a transparent plate 33 on which opaque copy material may be placed, a flexible cover 23 for holding the copy flat, a carriage 29 movable by means of wheels 31 along tracks 28 and having a transverse slit 30 extending there-across, lamps 9 which may be fixed to carriage 29 for uniformly illuminating the area of the slit 30, a lens 26 carried by a carriage 25 movable on ball bearings 27 along tracks 24, a light shield 21, and a transverse exposure slit 22. Rigidly connected with the shaft 35 of the drum 11 is a partial gear 34, the toothed portion 40 of which is engageable with a gear 37 which is rigidly connected with two pulley wheels 38, 39 which are in turn respectively connected to the two carriage 25, 29 by means of tapes 41, 42, the arrangement being such that during each revolution of the drum 11, the carriages 25,29 are moved in synchronism from one end of their respective tracks to the other for complete exposure of the copy material placed on plate 33 and are then returned to their original positions by the action of counterweights 45,47, in preparation for a further exposure cycle. The developing device is of the cascade type and comprises a hopper 51-for containing a two component developing powder-having in its lower wall a discharge orifice 54, a solenoid operated pivotally mounted gate 55 for controlling the flow of powder through the orifice 54, a shoot 61 for catching excess powder, a mixing chamber 62 which comprises an inclined cylindrical tumbler, having vanes 63, and rotatably mounted in bearings 65, and a bucket and chain elevator 70 for returning the powder to the hopper 51. An opening 62a is provided in the shoot 61 for recharging the developing device with powder. At the optional regeneration or reverse charging station 14 there is provided an electrode 72 comprising carona discharge wires 73, control electrodes 75 and an earthed plate 74. The paper feed device 15 comprises a tray 81 for supporting sheets 82, sheet feed means comprising levers 91,93 which are operated at the appropriate times by means of a cam 96 rigid with the drum 11 and a cam follower 95, feed rollers 83, 84 one of which is driven through gears 86-88 by means of partial gear 89 rigid with the drum 11, and pivoted pick-off fingers 101 which are operated by means of a cam follower 103 and a cam 104 rigid with drum 11. A transfer electrode 16, similar to electrode 72, may be provided to effect transfer of the developed image to the sheets. The sheets are then passed to a fixing station 105 which comprises a heated rotating drum 111 and a carona discharge electrode 112, the sheets adhering to the surface of the drum 111 during rotation therewith due to electrostatic attraction. Pick-off fingers 116 serve to direct the sheets into a discharge tray 117. The cleaning station 17 comprises a cylindrical brush 121-for example rabbit fur secured on a cylinder 127-which is rotated in a direction opposite to the drum 11, and a filter 128 is provided to remove dust and waste developer powder from the current of air generated by the rotation of the brush 121. An air blower may be provided to increase this current of air. A light source 131 may be provided to dissipate any residual electric charge from the surface of the drum 11. The charging electrode 18 is similar in construction to the electrode 72. In modifications, more than one cycle of operations may be accomplished during a single rotation of drum 11, and the drum 11 may be replaced by a photoconductive surface in the form of a plate or belt. U. S. A. Specifications 2,618,551 and 2,778,946 are referred to.