GB1040158A - Improvements in or connected with sheet feeding apparatus - Google Patents

Abstract

1,040,158. Feeding sheets. PARNALL & SONS Ltd. July 1, 1963 [July 6, 1962], No. 25956/62. Heading B6B. A sheet feeding apparatus incorporates magnetostrictive means for detecting faulty feeding of two or more overlapping sheets and comprises a transducer transmitter 29 and a transducer receiver 30 of longitudinal air pressure vibrations located on opposite sides of the path of feed of a sequence of sheets 12 and gain control means 33 for varying the sensitivity of the receiver 30 so as to distinguish between the presence of one and two or more overlapping sheets between the transmitter and receiver. Sheet feeling.-In operation a stack of sheets 11 is inserted in a magazine 10 with the sheets stacked on edge and parallel to the feed gap, the front face of the foremost sheet 12 being urged into engagement with a pair of ported belts 13 by supporting the magazine 10 on a conveyer belt 14. As the ported areas of the belts 13 reach the upper marginal part of the foremost sheet the vacuum in shoes 15 behind the belts 13 sucks the sheet against the belts whereby the sheet is lifted from the stack and transported into the region of a fixed head 17, where vacuum is applied to ports in a face 16 to suck on to this face any second sheet that may be adhering to the foremost sheet. After the upper marginal part of the foremost sheet has been advanced past the fixed head 17 and after application of vacuum to the fixed head ports the vacuum is then applied to the ports of a reverse running drum (not shown) in the fixed head 17, so that the drum tends to return any second sheet back towards the stack 11. Beyond the fixed head 17 the belts coact with idle roller 26, serving to advance the sheets to reading and/or sorting mechanism (not shown). Detection of faulty sheet feeding; trip arrangements.-If despite the operation of the aforesaid head 17 occasionally two overlapping sheets escape past it then they are intercepted between transducer transmitter output head 28 and transducer receiver 30 located on both sides of the feed path, both transmitter and receiver being connected to an amplifier 32 incorporating a sensitivity or gain control 33 and the amplifier output controls a relay 34 having terminals 35. The transmitter and receiver consist of magnetostriction transducers generating and receiving longitudinal air pressure vibrations preferably in the ultra-sonic range between 20 and 100 kc./sec. In setting up the machine the sensitivity control 33 is adjusted to give an acceptance of the thickness of the sheets, with a reasonable margin, without operation of the relay 34, whereas the presence of one or more thicknesses of sheets between the transmitter head 28 and receiver 30 gives rise to loss of signal in the receiver to operate the relay 34, which opens the electrical circuit through terminals 35, which action may be used to vent the vacuum shoes 15 to atmosphere to arrest further feeding of sheets and to operate, e.g. via a solenoid a deflector to divert all sheets in transit to a " reject " receptacle. Alternately the terminals may actuate an alarm device.