Kathodenstrahlrohr

摘要

1,249,346. Cathode-ray tubes. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 9 Oct., 1968 [11 Oct., 1967; 12 Oct., 1967; 13 Oct., 1967; 14 Oct., 1967; 16 Oct., 1967], No. 47941/68. Heading H1D. [Also in Division G3] In a cathode-ray tube having a linear target in the faceplate, e.g. a row of electrostatic printing pins or wires, a row or rows of optical fibres, or an elongated Lenard window 1, a pair of insulated electrodes 6, 61 are provided close to the target to pick up signals which are fed back to the deflecting plates 8, 81, or to a magnetic deflection system, whereby the beam is kept centred on the target. The signals may be picked up directly by the electrodes 6, 61, or inductively, in which case the electrodes are parallel plates at a slightly wider spacing than the width of the target. In the arrangement shown a rough positioning of the beam is effected by magnetic coils 16. An oscillator 18 provides a signal "wobbling" the beam perpendicular to the target and the signals picked up by the electrodes 6, 61 are amplified at 9, 91 and rectified at 10, 101 or (Fig. 5) combined and phase discriminated. Alternatively the signals may be compared in a potentiometer circuit.