Patent GB-1122627-A (GB)
Title: Sheet feed mechanism
IPC: B65H1/18
Filed: 1965-09-02
Abstract: 1,122,627. Feeding sheets. RANK XEROX Ltd. 2 Sept., 1965 [30 Sept., 1964], No. 37593/65. Heading B6B. Sheet feeding apparatus, particularly for a xerographic printer, comprises a table 41 for a stack of sheets 305, Figs. 1 and 4, an electric motor for raising and lowering the table, a sensor means which is periodically actuated to engage the top sheet of the stack and to cause the motor to raise the table if the top sheet is below a predetermined level, and a switch which is operated when the stack is sufficiently depleted to cause the motor to lower the table so that a fresh stack can be inserted. The sheets are separated by oscillating suckers 365 which place them over idler rolls 42 arranged beneath feed belts 44, and the latter convey them into the printer. Pile tables.-The table 41 for the stack of sheets 305 is guided vertically by rollers 308 in guide channels 309, and is supported by cables 310, having their upper ends secured in slots 315 in pulleys 313 fixed on a shaft 320. The shaft 320 is connected by gearing 321, 322, to a motor MOT-1 which is controlled by four switches. One switch 4LS is automatically operated when the stack is depleted, to cause the table 41 to be lowered; one switch (15LS) is opened when the table has been lowered sufficiently, and stops the motor; and one switch is manually-operated to cause the table to be raised from the lowered position. One switch (14 LS) causes the motor to raise the table 41 as the stack is depleted, and is actuated by a lever 323, secured on a pivot pin, and a stack sensing bar is also secured at one end to the pin, and is pivotally mounted at the other end. The lever 323, and hence the bar, is oscillated by a cam in synchronism with the sheet feeding movements as described below, and the switch 14LS is operated when the height of the stack is depleted by a predetermined extent. The stack is aligned on the table 41 and centred relative to the printing section of the machine by engaging the leading corner edges of the stack by a pair of adjustable guides 332, each having an upper lip 333 extending over the top corner of the stack. The guides are slidably mounted on a cross-shaft 320 and urged apart by a compression spring 340, and can be urged towards each other to suit the size of the paper sheets in the stack 305 by a system of levers 341, 345, &o. controlled by a manually-operable knob, having a pointer co-operating with a scale. The pointer is on a vertical lever having pawls thereon co-operating with pre-set stops. The rear margin of the stack 305 is aligned by deflectors biased by coil-springs. The entire deflector assembly can be rotated about stubshafts to facilitate loading of paper on to the tray. Sheet separators.-The sheets are separated sequentially from the stack 305 and advanced between idler rolls 42 and belts 44 by a number of suction feet 365 each comprising a hollow tube secured to a suction manifold tube, journalled in pivot arms secured to a rock-shaft 371. The tube is rocked by a cam 376, and the shaft 371 rooked by a second cam so that the lower ends of the suction feet 365 will be raised and then moved forward to feed a sheet. The operation of the suction feet 365 and the raising of the sensing bar is effected and synchronized by a rigid connection between two cams mounted on a shaft having a motor-driven gear rotatably mounted thereon and secured to one plate of a coil spring clutch. The clutch is a one-revolution clutch and is controlled by a solenoidoperated pawl, and the shaft can be driven by the motor to operate the sheet separator and the sensing bar. To ensure that the suction feet 365 start from the same position on each cycle, a third cam on the shaft co-operates with a spring- urged follower arm, the follower on the arm dropping into an indentation in the cam to stop rotation of the shaft after each cycle. The pump connected to the suction manifold has its pressure side connected to a manifold tube 395, having apertures therein from which compressed air is blown towards the leading edges of the topmost sheets of the stack 305.