GB313882A - Improvements in or relating to cathode ray tubes - Google Patents

Abstract

313,882. Associated Telephone & Telegraph Co., (Assignees of Richardson, R. G.). June 18, 1928, [Convention date]. Vacuum tubes.- The target of a cathode-ray tube for use as a telephone repeater consists of two segments, connected to the opposite ends of a centre tapped winding of a transformer in the output circuit, the cathode ray beam being deflected by the incoming speech currents so as to impinge intermittently on the segments. As shown in Fig. 1, a telephone repeater has a cathode 6, a perforated shield 7, a tubular anode 8, and a target consisting of insulated plates 9, 10 which are connected with the primary 15 of a transformer the mid-point of which is connected through a battery B<1> with the anode battery B. The beam is deflected by an electromagnet 11 having windings 17 carrying speech currents. The point of impact of the beam may be adjusted by varying a resistance 13 in series with a third winding 12 on the magnet. In the frequency-changer shown in Fig. 2, the target consists of a number of insulated segments 51 connected alternately in pairs, one set of segments being connected with one end of the primary of a transformer T, and the other set through a switch S with the other end. The beam is deflected by pairs of plates 41, 42 and 43, 44, of which the plates 41, 42 are connected across a resistance 48 and the plates 43, 44 across a resistance 47. The resistances 47, 48 are connected across a generator G, and inductance 46 being in series with the resistance 48 and a condenser 45 in series with the resistance 47, so that the voltages applied to the plates are out of phase. A filter may be connected in parallel with the primary of the transformer. The frequency of the output current is a multiple of the frequency of the deflecting potential, and is dependent upon the number of segments; two frequencies may be obtained by using a target having two concentric systems with more segments in one system than in the other.