GB1419510A - Sheet feeding devices - Google Patents

Abstract

1419510 Feeding sheets RANK XEROX Ltd 1 Dec 1972 55700/72 Heading B8R Sheet feeding apparatus comprises three compartments 31, Fig. 1, supporting piles of sheets in removable trays 151. Each compartment has rollers 61 for advancing the top sheet of a pile along a path defined by converging plates 91, 92, Fig. 3 to a pair of separating rollers 94, 102 associated with a particular site which prevent double feed. Guide plates 125 direct a single sheet from separating rollers 94, 102 to feed rollers 131, 138 which advance the sheet into a machine 21 such as a xerographic printer. Separating from the top of the pile (Figs. 8 to 9).-Each compartment 31 has a feed roller assembly comprising a pair of feed rollers 61 on a shaft (62). The shaft (62) is supported at one end of an arm (63) pivoted at its other end on shaft (64) adjacent the roof of the compartment 31. A torque tube (65) surrounds shaft (64) and is fixed to the arm (63). A lever (66) fixed to the torque tube (65) has notches (67, 68) which co-operated with a crank (77) manually operated by a handle 75 at the front of the compartment 31. The horizontal position of the handle (Fig. 8A) corresponds to the retention of the feed rollers 61 adjacent the roof of the compartment. The vertical position of the handle 75 allows the feed rollers 61 to rest under gravity on the top of the pile. The upper shaft (64) is driven by a sprocket (71) via an electron magnetic clutch (73). Shaft (64) drives shaft (62) via a belt and pulley system (not illustrated) within the hollow arm 63. Feed rollers 61 are provided with overrunning clutches (74) to allow them to rotate clockwise on shaft 62 should a sheet be withdrawn at a faster pace than the feed rollers 61. Preventing double feed (Figs. 3, 4, 6 and 7).- The roller assembly which prevents double feed comprises two pairs of knurled polyurethane surfaced rollers 94, 102 with the shaft (95) of the upper pair 94 journalled in fixed bearings and driven by a sprocket (97) via an eleetromagnetic clutch (99). Overrunning clutches 101 allow the rollers 94 to rotate clockwise on shaft 95. The shaft 103 of the lower pair of rollers 102 is journalled in bearings 106 movable in slots 107 to allow for movement towards and away from the upper shaft 95. A lever 112 is biased by a spring 116 against a ball race (111) centrally positioned on the lower shaft 103. The lower shaft 103 is anchored to the side plate 88 of the apparatus through a slip clutch (121) which has an anchor plate 122 provided with a roller 123 riding in a slot 124. The rollers 94 and 102 are urged together such that when no sheet or only one sheet is present between them, lower rollers 102 are rotated with sufficient torque to overcome the slip clutch (121) by the friction between the rollers 94 and 102 and the sheet if present. However, when two or more sheets are present, the friction between the sheets is insufficient to overcome the slip clutch so that the rollers 102 remain stationary and only the top sheet is advanced. A sensing device (not illustrated) such as a microswitch sounds an alarm and shuts down the machine should an excessively large number of sheets attempt to pass between the rollers 94 and 102, which could result in successive pressure and no slipping between adjacent sheets. Pile trays or cassettes (Figs. 12 and 13).- Each tray 151 comprises a base plate (152) with a fixed front margin guide (153). A rear margin guide (154) is movable relative to the base plate and is mounted on two pins (155) passing through a slot (150) and attached to a block (156) below the base plate. A right hand margin guide (164) is similarly mounted. The front and rear edge margin guides are provided with snubbers 161 which obstruct the passage of the top sheet as it is fed causing the sheet to buckle in order to pass thus facilitating separation. Two rows of rollers (175) on the underside of the tray allows it to be rolled into and out of the compartment 31 at right angles to the direction of feed. Rails 176 co-operate with one row of rollers to prevent skewing. Centering the pile (Figs. 13 and 14).-On the underside of each tray a link arm (181) is pivoted to the block 156 at one end and at the other end to the tray. Midway along the arm is a lug (184) which will move one half the distance of the rear margin guide (154). At the central rear portion of each compartment 31 is a device (179) comprising a lever (185, Fig. 4) mounted for limited rotation about a pin (187). A recess (186) in the lever locates the lug (184) to centre the pile. A spring loaded plunger (191) operates a micro-switch when the lug (184) is latched in position by spring latch (193). The block (156) is provided with a spring located lug (201) which engages registration notches (203) in a rotatable bar (202). The notches correspond to standard paper sheet widths. Feelers and detectors controlling separators (Fig. 3).-Microswitches 142 and 143 sense the passage of sheets through nip rollers 131, 138 and the top set of rollers 94, 102. Microswitch 142 on actuation causes the machine "logic" to deenergize the electromagnetic clutches (73) and (99) of the separator rollers 61 and feed rollers 94 respectively. Microswitch 143 is only in that path intended for short sheets whose trailing edge will have left separator feed rollers 61 before the leading edge reaches the actuating arm 144 of microswitch 142. Actuation of microswitch 143 causes deenergization of electromagnetic clutch 73 for rollers 61 in the upper compartment only, and also causes the energization of a lift clutch (78, Fig. 11) and a solenoid (86) so that rollers 61 are lifted from the top of the pile in the upper compartment. This prevents overloading of the feed rollers 94 by the drag of the overrunning rollers 61.