Patent GB-1295866-A (GB)
IPC: G03G15/26
Filed: 1969-11-24
Abstract: 1295866 Electro-photographic apparatus CANON K K 24 Nov 1969 [25 Nov 1968(5) 19 Feb 1969 28 Feb 1969 19 March 1969] 57397/69 Heading G2H An electro-photographic copying apparatus includes a holder 6, Fig. 1, for supporting a plurality of originals to be copied, the holder being movable to bring the sections individually to an exposure position, such that the original at the exposure position is stationary during copying. Copy sheets P are fed individually from a supply 1 into an exposure station 3 for exposure to an image of an original B placed on a holder 6 provided with means for holding two originals. The holder 6 has a base 10, Fig. 3, glass plate 11, pressure plate 12, the base being movable along guide rods 16 driven through a rack 17 meshing a gear G1 driven by a motor M controlled by micro-switches MS 2  and (MS 1 ) Fig. 2 (not shown). In a modification, Fig. 6 (not shown) the pressure plate 12 is divided into portions (12a) (12b). In another modification, Figs. 7 and 8 (not shown) the plate 11 is replaced by inclined portions (11<SP>1</SP>a, 11<SP>1</SP>b) oscillated by cam mechanism, Figs.9  and 10 (not shown). The holder 6 may be circular and rotated by motors 30 or 30<SP>1</SP>, Figs. 11 or 13 (not shown). A photo-electric cell PT 1 , Fig.15, detects the double feed of copy sheets P to close a passage 47 upon energization of an electromagnet 52 which actuates a lever 49, thereby discharging the double fed sheet P<SP>1</SP> along a guide 55. Correctly fed copy sheets P are guided by nylon strings (66) Fig.17 (not shown) through a corona charging apparatus 2, Fig.1. Switches (MS5, MS6), Fig.17 (not shown) are closed when strings (66) are cut or loosened to detect faulty feed; closure of these switches lights a lamp, stops the feed, and sounds a buzzer (not shown). The contrast of originals to be copied is detected by a light source (L3) and a phototransistor (PT 3  Fig. 23 (not shown) positioned beneath the plate 11, Fig. 1, to produce a signal corresponding to the brightest area of the original when scanning an original. This signal is fed to a circuit, Fig. 21 (not shown) which controls the exposure. A light source L4 and photo-conductor CdS4, Fig. 25, detect the concentration of toner on developed copy sheets fed through rollers 81, 82<SP>1</SP>, Fig.1, adjacent developing apparatus 4. A balance circuit, Figs. 26 or 27 (not shown) controls a relay which in turn controls the supply of developer concentrate. A modified circuit, Fig. 28 (not shown) controls the supply of developed concentrate dependent upon a predetermined counted number of copy sheets. A chamber 88, Fig.30, collects air in the vicinity of firing station 5, Fig.1, by a fan so that purified air is discharged into the surrounding atmosphere. The chamber 88 contains replaceable cassettes of carbon 101 to effect filtration. In a modification, Fig.34 (not shown) heated air is blown against the rear surface of copy sheet P, while a cooling tube (114) circulates cool air, water, or gas so that air circulated by fans (99, 100) is discharged in the vicinity of light source 7, Fig.1, the cooled vapour being condensed and stored in a reservoir 119.