Patent GB-218346-A (GB)
Title: Improvements in and relating to feeding devices for webs of paper and other material
IPC: B41F13/02
Filed: 1923-02-03
Abstract: 218,346. Humphreys, H. Feb. 3, 1923. Registering webs.-Relates to the method of correcting errors of register in feeding a previously marked or printed web to a cutting, printing, perforating, folding, or other device, in which perforations in the web co-operate with a detector to close an electric current to retard or accelerate the web relatively to the cutting &c. device if a perforation arrives at the detector early or late with respect to the disposition of an element moving in synchronism with the cutting &c. device or the web-feeding device, and consists in terminating the retarding or accelerating action after a predetermined time irrespective of the extent or duration of the error. Fig. 1 shows an arrangement for correcting errors which cause the perforations to creep in advance of their correct position. The web passes between a detector a and a roller A of conducting material with which contacts a brush a<1> connected to a brush b' contacting with a controller B, rotating in synchronism with the cutting &c. device and provided with an insulating strip b. Brushes b<1>, b<3>. also contacting with the controller B, are connected respectively to a positive main 1, and to a switch arm 5 forming the armature of an electromagnet 4 in the negative main 3 to which the detector a is connected. A circuit 7, 8 is connected to web-retarding means of any suitable. form such as a brake applied to the frictional drive of the feed rollers, or a device for varying the length of the path of the web. The feed rollers are initially set to feed a length of web., not less than the maximum distance between consecutive perforations, for each operation of the cutting &c. device, and the controller B is set so that the strip b engages the brush b<2> when the perforations pass beneath the detector a so that the circuits remain open. If the web is in advance of its correct position, the perforation arrives at the detector a before the strip b arrives at the brush b<2> and current flows from the main 1 through the brush b<1>, controller B, brushes b<2>, a<1>, roller A, detector a and circuit 7, 8 to retard the web. The magnet 4 closes the switch arm 5 to maintain the current through the circuit 7, 8 by means of the circuit 1, b<1>, 13, b<3>, after the circuit through the brush b<2> has been broken by the strip b. One of the brushes b<3>, b<1> is in the path of the strip b so that the circuit 7, 8 is broken by the strip b after a period which may be varied by adjusting the position of .that brush relatively. to the brush b<2>. In a modification, Fig. 2, a rotary detector a co-operates with a controller A<1> having an insulation strip b and two brushes b<2>, b' in the path of the strip. The apparatus is set so that the perforations normally pass just to the rear of the detector and the circuits remain open. It the web is in advance of its correct position, a circuit is established through the main 1, detector a, controller A<1>, brush b<2> and main 3, the switch 5 being actuated to maintain the current through the circuit 7, 8 of the retarding device until the strip b engages a brush b<3>. Arrangements similar to those shown in Figs. 1 and 2 may be employed to correct errors which cause the perforations to lag behind their correct position, the circuit 7, 8 being adapted to operate means for accelerating the speed of the web. The acceleration of the web may be effected by releasing a brake normally acting upon the feed rollers. Fig. 3 shows an arrangement for correcting errors resulting in either creep or lag of the perforations. In this arrangement the feed rollers may be driven by a reversible motor operating through a sun and planet gearing such as described in Specification 183,413, the motor being driven to retard the feed by current in a circuit 7<a>, 8<a>, and to accelerat the feed by current in a circuit 7, 8. Two detectors a, a* and two corresponding controllers B, l<p> are employed and the parts are initially set so that the perforations pass under the detectors a when the insulation strip b meets the base e, and under the detector a* when the strip b<1> is leaving the brush f so that no current passes through the circuit. If a perforation is in advance of its correct position it arrives at the detector a before the strip b meets the brush e and the circuit 7<a>, 8<a> is closed. If the perforation is behind its correct position it arrives at the detector a* after the strip b<1> has left the brush f and the circuit 7, 8 is closed. The circuits are maintained for a definite period in a similar manner to that described above with reference to Fig. 1. In a modification of the arrangement shown in Fig. 3, the two controllers B, B<1> are replaced by a single controller. Specifications 21222/07 and 218,608 also are referred to.