Patent GB-1023541-A (GB)
Title: Improvements in or relating to electrophotographic copying machines
Inventor: ROBERTSON ALEXANDER LIDDELL
IPC: G03G15/28
Filed: 1961-01-04
Abstract: 1,023,541. Electrophotographic projection copying apparatus. OZALID CO., Ltd. Mar. 29, 1962 [Jan. 4, 1961], No. 305/61. Headings G2A and G2H. An electrophotographic copying machine comprises means for feeding an original to be copied and an electrostatically charged copy sheet of electrophotographic material towards one another in synchronism and at the same speed along aligned paths, an optical system for illuminating with actinic radiation successively transverse increments of the original starting from its leading end and projecting via reflecting means on to the copy sheet corresponding successive slit images of these increments at unit magnification, and means for conducting the exposed copy sheet through a developing zone. Preferably a detector is located in the path of the original and when passage of the leading end of the original is sensed means are operated by the detector to start the feeding means for a web of electrophotographic material, and similarly the feeding means is stopped on passage of the trailing end of the original while means for severing a sheet of the same size as the original is also operated. If more than one copy is to be made from the same original, the original is fed round a closed path and a second detector located in said path controls the feeding of the copy web and the severing of sheets from it. As shown, when the leading edge of an original inserted by hand over table 6 into the machine between a driven roller 7 and a backing roller 17 passes a photo-electric sensing unit 48, 68, a driving roller 5 is operated to feed a web of electrophotographic paper over rollers 43 beneath a corona charging unit 44 and a gate 3 closing the inlet 2 is released. The original passes through guides 11, 12, 13 and pairs of rollers, of which rollers 7, 9 are driven, to an illumination station Eg in guides 14 where a lamp 15 and ellipsoidal reflector having foci at 15 and 21 lights successively presented areas of the original, images of which are projected at unit magnification by lens 23 and mirror 22 on to the copy sheet at E 1  as it passes over the rollers 43. The original after illumination is deflected by a guide 26 around a roller 25 and thence passes between guides 30, 31, 33 andpairs of rollers of which the lower members are driven. If a single copy only is required, pivoted stripper fingers 35 are in a rest position against the roller 18 so that the original will be delivered into the tray 37. On passage of the trailing end of the original past the sensing unit 48, 68 the gate 3 is raised, the copy web driving roller 5 is stopped, and the web is arrested by a solenoid operated clamp 41 while a guillotine 42 is operated to cut off a sheet of the required length. To allow the portion undergoing exposure to continue its movement uniformly a loop-forming assembly including driving rollers 53, 59 mounted on a plate 55 pivoted at 56 is moved by a solenoid S F  to straighten the loop. If a number of copies are to be made from the same original a selector switch (not shown) is operated, making connections in a control circuit to an appropriate number of contacts on a stepping counter, and the finger 35 are moved to the position shown. When the trailing end of the original passes the sensing unit 48, 68 the roller 5, clamp 41 and guillotine 42 are operated as before but the gate 3 is not lbwered, an alternative hold-on circuit for the relay controlling the gate being provided. When the leading edge of the original reaches a second sensing unit 49, 69 previously having its output muted, the sequence of operation initiated by the unit 48, 68 is repeated and the counter switch is stepped on by a relay energized by a switch operated by the guillotine. This is repeated until a selected contact of the selector switch is reached by the stepping counter wiper when the stripper fingers are moved to their other position against the roller 18, the stepping counter is reset to its initial position, and on this final passage of the trailing end of the original past the sensing unit 49, 69 the gate 3 is raised. Fig. 2 (not shown) which shows an electrical control circuit for the machine shows a manual switch for independent feed of the paper web. The Provisional Specification refers to the use of suction to hold the copy sheet and original flat during the projection copying and to employing rollers for sensing the passage of the leading and trailing ends of the original.