Patent GB-530314-A (GB)
Title: Control mechanism for printing presses
IPC: B41F33/02
Filed: 1939-06-02
Abstract: 530,314. Photo-electric apparatus for control. ling multiple-roll printing presses. ION CORPORATION. June 2, 1939, No. 16317. Convention date, June 2, 1938. [Class 40 (iii)] [Also in Group XXXVII] A multiple-roll printing press is provided with cathode-ray tubes to indicate the phase relationship between the application of markings to a web being printed by each of the printing rolls and the passage of such markings past a predetermined point so as to enable the registration between the web and the roll to be adjusted, the said markings being applied in strict timed relationship with the rotation of the printing rolls. As shown in Fig. 1, the press comprises four printing rolls R1...R4 driven by a common shaft S from a motor M. The web P is fed from a roll p and over tensioning rolls T1 ... T4, each of which can be adjusted by manually operated devices t<SP>1</SP>...t<SP>4</SP> to adjust the web in relation to the corresponding printing roll. The printing rolls are intended to impress successive colours on the same spaces of the web. At the same time, each printing roll impresses a mark in margins at the sides of the spaces. These markings then pass under photo-electric devices F1...F4, Fig. 1, where they produce signals which are transmitted to cathode-ray tubes C1...C4. When the successive colours are applied in correct registration by the successive printing rolls, deflection in luminous lines produced by the cathode-ray tubes all appear at the vertical central line of the screen of the tube. Lack of registration of any one roll is indicated by a displacement of the luminous deflection of the corresponding cathode-ray tube to one side or the other of the central vertical line, and this enables the corresponding device ti, t<SP>2</SP>, t<SP>3</SP> or t<SP>4</SP> to be adjusted to restore correct registration. Photo-electric apparatus.-The photo-electric apparatus shown in Fig. 8 comprises a lamp 1 in a housing 2 sending light through an aperture 3 and a tube 6 containing lenses 4, 7 to a prism 8 which deflects the light through an aperture 9 to the web p. Light from the web passes back through aperture 9, part of this light goes directly to a photo-cell 11, and another part is reflected to this cell by a parabolic reflector 10 which has the aperture 9. On its way through the tube 6, the light is periodically interrupted by a perforated shutter 12 rotated at a high speed by a motor 13, this pulsation of the light enabling the corresponding pulsations of the output of the photo-cell to be dealt with by a thermionic valve apparatus. In this apparatus. shown in Fig. 13, the pulsating output of the photo-electric cell 11 is passed through pentode 20 and triode 21 to full-wave rectifier 25, the output of which is then inverted by triode 27 and fed to the vertical controlling electrodes 32 of a cathode-ray tube. Cathode-ray tube apparatus.-As shown in Fig. 12, this apparatus follows generally wellknown lines. It is fed from a source of alternating current connected to a transformer primary 50 through a lamp 51 and a switch 52. Two transformer secondaries 54, 55 are connected to valve rectifiers 56, 57 both yielding direct current at a voltage of 210 volts. The output of the rectifier 56 is connected across a resistance 40, the positive end of which is connected to earth. The output of the other rectifier 57 is connected across a resistance 59, the negative end of which is connected through a switch 58 to a contact arm 42 rotatable over the resistance 40. A centre tapping 60 of the resistance 59 is connected to one of the horizontal controlling electrodes 34 of a cathode-ray tube C and the other electrode 34 is connected to earth. As a result of these connections, the continuous rotation of the contact arm 42 over the resistance 40 causes the cathode-ray to traverse the screen from left to right once for every revolution of the contact arm 42. This arm is intended to be driven by gearing from the main motor M, Fig. 1, so that the cathode-ray is timed in relationship with the rotation of the printing rolls. The signals produced by the photo-electric cell 11 and associated amplifier-rectifier-inverter device indicated diagrammatically as A1 in Fig. 12 are fed to the vertical controlling electrodes 32 of the cathode-ray tube in timed relationship with the passage of the marks on the web, and therefore produce a vertical deflection of the cathode-ray at the vertical central line when the registration is correct; whereas if the web and printing roll are not in correct register the deflection lies to one side or the other of the central vertical line. The vertical electrodes 32 are fed from the transformer secondary 62, the photo-cell 11 and valve apparatus A1 being inserted in this circuit with a byepass preventing resistance 63. The horizontal electrodes 34 are fed from a transformer secondary 65 through the switch 58 when this cuts off the control from the contact arm 42 when the press is not working. The power supply circuit of the cathode-ray tube is supplied from .the transformer secondary 64 in the usual way. In a simpler form of apparatus, the electrodes 34 are fed by a battery in conjunction with a resistance 40 with its rotating contactarm. The Specification, as open to inspection under Sect. 91 describes also a potentiometer, Figs. 13 and 15 (Cancelled), comprising a resistance made up of short lengths 40a connected to insulated contacts 66 arranged in a circle. An arm 42 with an insulated plunger 67 is rotated over the circle of the contacts 66 by gearing 43, and is provided with an opposite plunger connected to the plunger 67 and riding against a fixed insulated contact ring 68 for external connection. This subject-matter does not appear in the Specification as accepted.