Patent GB-218608-A (GB)
Abstract: 218,608. 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 cause the operation of means for retarding or accelerating the speed of the web relatively to the cutting &c. device if a perforation arrives early or late at the detecting position, and consists in initially adjusting the speed of the web relatively to the. cutting &c. device so that any errors occurring will result in causing the perforations only to creep in advance of their correct position or only to lag behind. 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' connected to a brush b<2> contacting with a controller F, rotating in synchronism with the cutting &c. device, and provided with an insulation 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 reaches the brush b<2> and current flows from the main 1 through 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>, B, b<3>, after the circuit through the brush b<2> has been broken through 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-orerates with a controller A' having an insulation strip b and two brushes b<2>, b<3> 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. If 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 the brush b<3>. Similar arrangements 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, which are initiallv set to feed an amount not more than the minimum distance between consecutive perforations for each operation of the cutting &c. device. Specifications 21222/07 and 218,346 are referred to.