Patent GB-1032951-A (GB)
Title: Improvements in xerographic reproducing apparatus
IPC: B65H3/54
Filed: 1962-12-28
Abstract: 1,032,951. Xerographic copying apparatus: projection printing apparatus. RANK XEROX Ltd. Dec. 28,1962 [Dec. 28,1961], No. 48954/62. Headings G2A and G2H. A xerographic copying machine comprises a rotatable drum having a photoconductive surface upon which for production of an electrostatic image there is projected an optical image of an original to be copied, the surface of the drum when rotated to effect a copying cycle passing through a number of processing stations, an original carrier connected for rotation in synchronism with the drum, controllable grippers associated with the original carrier, and a control system which in a first position permits the grippers to hold an original on the carrier and in a second position permits actuation of the grippers to release the original, the system including a counter responsive to the number of copying cycles effected by the drum, which counter for the production of multiple copies of an original is set in accordance with the number of copies to be made and causes the control system to assume the first position until the drum has completed a number of copying cycles one less than the number of copies set on the counter and subsequently to assume the second position. As shown, the original carrier is a drum 30 on shaft SH2 rotatable at the same speed as the xerographic drum 20 on shaft SH1 by means of a common drive chain operated by an electric motor MOT-3. On feeding an original into the machine via guides 37, an arm 701 operates switch 6LS to start the machine, the original becoming held on the drum 30 by gripper fingers 142 by cooperation of document stops 107, document retainers 108, and pressure fingers 106 as the drum rotates, as illustrated by Figures 6 to 13, not shown. An image of the document at unit magnification is projected on to the xerographic drum 20 through a slotted light shield 33 by an optical system including mirrors 34, 36 and lens 35. The drum 20 is rotated through the usual corona charging, exposure, cascade development, and corona powder image transfer stations, and then a corona cleaning station 84, and past a cleaning web 403 fed counter to it as in Specification 1, 032, 957 and a residual charge-dissipating lamp 85. An image-receiving paper sheet is fed by rollers 61 from a stack in a tray 60 by a chain conveyer 62 as in Specifications 1, 032, 956 and 1, 032, 958 into contact with the drum 20, and after transfer of the powder image is fed through a fuser 70 as in Specification 1, 032, 955 to fix the image and deliver the finished copy to the exterior of the machine from between rollers 65, 66. Since the length of the conveyer chain is twice the circumference of the drums, it is necessary in order to clear the paper sheet out of the machine to make the operating cycle duration for a single print equal to three revolutions of the drum. The paper feed rollers are lifted off the stack by a lever system 277, 276, 249 controlled by a cam 281 (Fig. 14, not shown) on the shaft SH1 of the drum 20 and the document being copied is ejected from the drum 30 during the first revolution whereupon the "time out" cam 630 (Figs. 14,18,19,20, not shown) on shaft SH11 becomes clutched to the machine drive and ensures operation of the drum and conveyer drive for two more revolutions, shaft SH11 being driven from the main drive motor at 1/ 3  speed of shafts SH1, SH2. A return spring for the cam is tensioned as it rotates, this spring thus being tensioned in the stand-by condition of the apparatus. In the stand-by condition, switch SW1 being closed, safety panel interlock switches 1LS,2LS, 4LS and switches 3LS and 13LS operated by inserting the paper tray and developing mechanism are closed, blower motors MOT- 1 and MOT-4 are energized, and the switches, 8LS, 9LS, 12LS controlled by the "time out" cam 630 are operated. On inserting a document into the guide 37, switch 6LS is closed and energizes a solenoid SOL-1. This declutches the "time out" cam 630 from the shaft SH11 and the cam is returned by its spring to its home position where it allows actuators for the three switches 8LS, 9LS, 12LS to release the switches which assume the positions shown. Solenoid SOL-1 is thus de-energized but the clutch is prevented from connecting the "time out" cam to the shaft SH11 by a latch 673 (Figs. 18 to 20, not shown). Simultaneously the drive motor MOT-3 for the drums 20, 30, paper conveyer 62 and peper feed rollers 61 and motor MOT-2 for the cascade developer are energized, solenoid SOL-2 is energized to open the gate 541 to the fuser 70, the document illuminating lamps are energized, and the corona charging and transfer units are energized, together with the charge-dissipating lamp. As the drums rotate, cam 281 causes linkage comprising arms 277,276,249 to lower the paper feed rollers on to the stack. A counter indicating the total number of prints made by the machine is operated by a pivoted lever carrying a follower for a cam 685 (Fig. 14, not shown) on the shaft SH1, the lever being held clear of this cam during "time out" operation by a surface on the "time out" cam 630. For single print operation switch 7LS is open, and when cam 281 raises the paper feed rollers, latch 673 is freed from the latch end 279 (Fig. 18, not shown) of arm 277 to allow the clutch dog 641 (Fig.20, not shown) to re-engage the "time out" cam. This is then rotated and maintains machine operation until the print is delivered from the machine the cam then actuating switches 8LS, 9LS, 12LS to shut down the machine to the stand-by condition. If a further document is fed into the guides 37 on the tail of the first, switch 5LS controlled by a cam 164 (Fig. 4, not shown) on the shaft SH2 energizes via document-closed switch 6LS the clutch release solenoid SOL-1, so that the "time out" cam is released to allow another paper feed sequence. For multiple prints from the same document the document ejection rollers 42 are held clear of the drum 30 and the document gripper fingers 142 are not released. This is achieved by pushing inwards the knob 6 of a programmer unit and rotating it clockwise from the zero position, e.g. to the position shown, a pin on the programmer shaft engaging a fixed ratchet wheel 623. The inward movement moves a cam 602 axially out of engagement with switch 7LS which closes to form a holdon circuit for the "time out" cam clutch release solenoid SOL-1 so permitting successive paper feed operations, and rotation of the cam pivots a lever 161 to move the document feed out rollers clear of the drum and the interposer pin 151 out of the path of the cam 143 on rocker shaft lever 148, which normally causes momentary release of the document gripper fingers 142, and into engagement with a latch stop member 115 which, once a document has been supplied to the drum, holds the document stops and pressure fingers clear of the document. At each revolution of the drums a driving pawl 618 operated by a cam 609 on the shaft SH2 and engaging a toothed wheel 606 rotates anticlockwise the programmer unit shaft one step. When the last print of the series is being made, the programmer shaft brings the detent pin into engagement with a large recess on the fixed ratchet wheel 623 so that the shaft moves outwardly whereby cam 602 opens the switch 7LS. By this time the cam has rotated to place the interposer pin in the path of rocker shaft cam 143, so releasing the document grippers, and returned the document feed out rollers to their operative position, so that the document is ejected and the "time out" cam becomes operative to feed out the last print and return the machine to stand-by condition. During a machine copying cycle a signal lamp LMP-11 is illuminated, warning the operator not to adjust the programmer unit. A warning buzzer operated by solenoid SOL-3 is actuated by closure of switch 10LS when the paper supply becomes low and warning lamps are energized through contacts 11LS-A when switch 11LS is actuated by the growth of the take-up roll of the web cleaner unit, indicating need for replacement.