GB784744A - Improvements relating to record controlled recording apparatus - Google Patents

Abstract

784,744. Photo-electric control systems. FORMBY & CO., Ltd., J. May 18, 1955 [Feb. 18, 1954], No. 4829/54. Class 40 (3). [Also in Groups XVI, XIX and XXXVIII] A record-controlled printing machine, in which the record comprises a magnetic film 31a having symbols represented thereon, comprises a sensing device to control a discriminating device 2 having a cyclic magnetic track 31 which records a spot at a position distinctive of the symbol number and value, and reproducing means 6 energized at a time dependent on the position of the spot on the track 3<SP>1</SP> to control the printing. The symbols recorded on the primary magnetic track 31a are in the form of a number of pulses, the number of pulses representing the value of each symbol. Each symbol gives rise to a series of pulses which are passed to the discriminating device 2 comprising a pair of high-speed primed trigger valves 38 and a pair of ten cathode gas glow valves 39 thus causing the cathode glow to step to the appropriate cathode and prime an associated trigger tube 40. A timing signal is applied simultaneously for example via photo-electric cell 61 and amplifier 62 to the grids of the triggers 40 (point x) and the particular trigger which is primed, strikes, so applying current to the operating coil 41 of a recording head 4, Fig. 4, and a spot is recorded on the cyclic magnetic track 3<SP>1</SP>. The next signal is routed via the second gas glow valve 39, to give more time for the cathode glow of the first valve to return to zero. The change-over is effected by two trigger tubes 48 energized by a light source 52 which transmits a light pulse to a cell 56 at the end of each consecutive symbol determined by thirty-two holes spaced equally round a control disc 1 on a shaft 5 rotating together with the track 3<SP>1</SP>. The symbol sensed by the recording heads 4 are recorded on the magnetic track 3<SP>1</SP> on the periphery of a record disc 3. This track, in the embodiment shown, is divided into 384 equally spaced spot positions and a train of 16 symbols to be recorded on the track 31, each of the value 0-9, may be recorded on one half of a revolution of the disc 3. The recording heads 4 are placed at intervals of 17 spaces and primary signals from the tape 31a are presented via the discriminating unit 2 at regular intervals so the disc 3 and the control disc 1 rotate through an angle equivalent to 12 spot positions. A first symbol signal for the digit 3 would operate the recording head in the 3 X 17 spot position while a second digit, e.g. 5, would operate a recording head in the 5 X 17 original spot position although the disc itself would have moved 12 spot positions-that is, the spot is recorded in the (5 x 17) + 12 spot position. The spots on the magnetic track 3<SP>1</SP> are sensed by reproducing head 6 spaced twelve intervals apart. Other combinations of intervals between spots and the positions of the recording head may be used provided that the spots arising from different symbols of a train do not clash with each other. Also, provision may be made for more than ten symbol values. Each reproduction head is associated with a distinctive printing wheel p, Fig. 3, which is directly coupled to the shaft 5 so that an impression is made in the required position by a toggle 28 or hammer mechanism whilst the wheel is rotating. A gap between the first and last recording head enables the paper to be fed,