GB732670A - Improvements in or relating to means for detecting loss of register, failure or transfer, or inaccurate movement, of paper in printing or like machines - Google Patents

Abstract

732,670. Feeding sheets; printing-machines. WARNER-JONES & CO., Ltd., K. Aug. 3, 1951 [May 8, 1950; June 8, 1950], Nos. 11365/50 and 14312/50. Classes 100 (1) and 100 (2). Faulty feed control devices.-Detecting-apparatus for a printing or like machine comprises a pneumatic actuator connected by a duct with a source of vacuum and operatively associated with control mechanism on the machine, and at least one detector duct leading from the actuator to a detection location and having at least one aperture at the location disposed in a situation such that only when a sheet is correctly positioned on the machine will the aperture be covered by the sheet, and such that exposure of an aperture due to a sheet being out of its correct position, will cause operation of the. actuator and appropriate functioning of the control mechanism. As shown, the apertures 25 are located above a surface 2, lays being provided so that only when the sheet is correctly positioned will the aperture be closed. The actuator 4 is connected to a source of vacuum by a duct 23 and to the aperture 25 by a duct 3, and comprises a fixed plate 5, movable plate 6 and bellows 7. In the presence of a sheet correctly positioned the bellows collapse so as to operate a rod 8 which moves a lever 10, pivoted at 11, out of the path of a lever 16 pivoted at 13 and oscillated by means of a cam 18, and cam follower on a second lever arm 14. The lever arm 16 is thus free to move anticlockwise under the action of a spring 21, thereby moving a rod 19 which puts the machine in an operative condition. Should the sheet be faultily positioned the bellows 7 expand, moving the lever 10 to the position shown in full lines so that after the next rotation of the part 22 of the cam 18 the lever 16 will be prevented from moving by abutment therewith. The rod 19 being thereby constrained from movement will maintain the machine inoperative. The lever 16 is such that the lever 10 is not released until the next revolution of cam 18, should a sheet then be correctly positioned. To prevent over-running of the sheet a second detector unit may be provided co-operating with a further lever arm pivoted at 13 and rotating with the lever 16, the arrangement being such that the machine is rendered inoperative if a sheet is detected by the second unit at the same time as by the first (Fig. 3, not shown). The pneumatic actuator may operate an electrical circuit which controls movement of the rod 8 and may consist of a movable piston linked to a pivoted mercury switch (Fig. 4, not shown), a diaphragm arrangement, one contact being mounted on the diaphragm and the other fixed (Fig. 5, not shown), or a U-tube having two fixed contacts therein and containing mercury, the level of which is varied by the vacuum created in one end thereof (Fig. 6, not shown). The apertures 25, instead of being constituted by slots at the end of one or more ducts 3 may be formed on a roller rotating in timed relation with the cam 18, the apertures co-operating with a central bore in the roller connected through a valve to the duct 3. The apertures 25 may be located above or below the sheet and the apparatus used to detect faulty side as well as front registration. Tripping arrangements.-The apparatus may be used for stopping printing-machines if sheets are not corrctly positioned, or for controlling the impression in printing-machines.