Patent GB-548031-A (GB)
Title: Improvements in or relating to machines through which paper and like sheets are passed
Filed: 1941-08-15
Abstract: 548,031. Photo-electric control of sheet feeding machines. BROIDO, D. Aug. 15, 1941, No. 10384. [Class 40 (iii)] In a machine for dealing with sheets, for example a machine as in Specification 532,416 for dealing with sheets having code marks such as 98, Fig. 5, the sheet 13, Fig. 5, is provided with a control mark 200 comprising a substantially transparent area enclosed in a substantially opaque area, and the machine has an aperture 207, Fig. 2, of predetermined size adapted to register with the transparent area of the mark 200 when the sheet is correctly positioned in the machine. In these circumstances, a predetermined amount of light will pass from a lamp 201 to a photo-electric cell 208, and the machine will perform its intended operations. If the mark 200 is incorrectly aligned with the aperture 207, less light passes to the cell 208, and this causes the sheet to be discarded into a separate receptacle 229, Fig. 1, by a flap 225. The defective alignment may be due to a defect in the position of the sheet in the machine or a defect in the position of the marks on the sheet, moreover, if two sheets are accidentally fed to the machine at the same time, the double thickness causes a reduced light transmission, so that the superimposed sheets are discarded like defective sheets. The machine may also be arranged to discard sheets from which the part marked with the mark 200 has been torn off ; this being brought about by an increase of transmitted light above the predetermined amount. If a sheet is unmarked or if the misalignment of a sheet marked as in Fig. 5 exceeds the size of the black mark, the photo-electric device will act as if the sheet was in order. To avoid this, the mark may be so made, however, that its transparent part is not as transparent as the plain sheet, for example the white centre of the mark may have a centre black spot, Fig. 9, or a transverse black line, Fig. 8. If such a mark is wholly displaced from the light beam, an amount of light in excess of the predetermined amount will reach the cell through the unmarked part of the sheet and will cause the rejection of the sheet. In the apparatus shown in Fig. 4, a notch 231 in a cam 230 rotating with the scanning drum 21 releases a lever 233 at the time when the mark 200 is due to come opposite the aperture 27. The lever 233 is swung counterclockwise by a spring 235 and unlocks an armature 218. If the mark on the sheet is in correct register, an electromagnet 213 retains the armature 218 in the position shown, and the machine performs its usual operations. If the mark on the sheet is not in correct register, the electromagnet 213, which is controlled by the photo-electric cell, allows the armature 218 to be swung clockwise against a stop 217 by a spring 220. A pin 221 on a bell-crank 222 is released by the armature and is rocked clockwise by a spring 224. A flap 225, Fig. 1, on the shaft 223 of the bell-crank is therefore also rocked and the sheet is thereby deflected into the receptacle 229, whereas when the registration of the control mark 200 is correct, the sheets pass over the flap 225 and are sorted into the receptacles 70, 71 in the usual way in accordance with the correspondence of the code marks 98 of the sheet with the setting of the apertures 91 of the scanning drum 21. Before the next sheet comes to be dealt with, a lever 124, Fig. 4, is deflected by a cam projection 52 rotating with the scanning drum, and a rod 121 is thereby moved to the right. A tappet 245 bears on the bell-crank 222 and restores this bell-crank and the flap 225 to the position shown ; and a tappet 242 then restores the armature to the locking position shown, a spring pawl 236 on the lever 233 allowing the armature to pass back to the locking position. In the modification, Fig. 6, a lever 260 without a spring pawl is released by a cam notch 263 and a second cam notch 264 is added to release the lever again during the return of the mechanism to normal, this being required in the absence of the spring pawl 236 of Fig. 4. A three-armed lever 253 has a pin 258 on one arm for locking engagement with the forked end 259 of lever 260, a pin 255 on another arm for locking engagement with a stud 256 on a bellcrank 257, and a joint 252 on the third arm connected to two cores 251, 256 of two solenoids 250, 265. The solenoid 250 is controlled by the photo-electric device, and the solenoid 265 is energized by a battery 268. The swing of the three-armed lever 253 is limited by adjustable stops 274. In this modification, a correct amount of light passed by the control mark causes the electromagnet 250 to balance the electromagnet 265, the parts then retain the locked position shown. If the amount of light is less or more than the predetermined amount, one or the other of the electromagnets causes the three-armed lever to be rocked in one direction or the other ; in either case, the bell-crank is released and the sheet (or sheets) discarded. In addition, when the sheet is thus discarded, a switch 271 is closed by the rocking bell-crank and energizes the electromagnet 110 independently of the photoelectric control of this electromagnet, so that the flap 69 and other devices that may be controlled by the electromagnet 110 are not affected by the discarding operation of the rocker 253. This is desirable, for example, when the flap 69 is associated with a counting mechanism.