Patent GB-190502691-A (GB)
Title: Improvements in Electric Signalling Systems, and Apparatus therefor.
Filed: 1905-02-09
Granted: 1906-01-25
Abstract: 2691. British Thomson-Houston Co., [General Electric Co.]. Feb. 9. Range - finders.-Relates to electric signalling- systems and particularly to range-finders for use in connexion with torpedoes &c. in the defence of harbours. Two transmitters, located at suitable points near the harbour, are provided with observing - telescopes and with rotatable members revolving in synchronism with the receivers, arranged in connection with a suitable chart of the harbour. Once in each revolution of the rotating member of the transmitter, a current impulse is sent to the receiver and causes an indication to be given on the chart, corresponding to the position of the observing-telescope. The indication is preferably given by flashing a line of light across the chart, and, as two pairs of instruments are operated together, the intersection of the lines of light gives the position of the observed object. The instruments are rotated rapidly so that the flashes occur at brief intervals and appear continuous. A special method of starting the synchronous motors of the transmitter and receiver in: phase is described. In the transmitter, Fig. 2, the telescope 10 is carried by a plate 9 mounted on a shaft 8 loose in the sleeve 7,-so that the telescope can be turned in any position. The plate 9 carries a brush 12 which engages a metallic segment 17, Figs. 2 and 7, on the disk 14 rotated rapidly by the motor 19. Current. is supplied to the segment 17 by a ring 15 and a brush 15. The instant at which contact is made between the brush 12 and segment 17 thus depends on the angular position of the telescope. Fig. 4 is a sectional elevation of the receiving-instrument. The upper part of the instrument is continuously revolved by the synchronous motor 24 and gearing 23, 22. The mechanism for flashing the beam of light across the chart is mounted on the rods 25, 25<1>, and comprises a casing 26 containing an incandescent lamp 28, and a magnet 32, which, when energized by the current from the transmitter, moves the shutter 31, Fig. 5, across the slot 30 in the casing 26. During the momentary coincidence of the slots in the shutter and casing, the image of the lamp filament is focused on the chart by the lens 36. The filament is attachment at its upper end to a spring 28<1> to hold it taut. The filament may be focused while the casing 26 &c. is rotating by turning a hand-wheel, which varies the distance between the lens 36 and casing 26. Another form of lamp is described, in which the filament is horizontal and the armature of the magnet 32 carries a mirror which flashes the image of the filament on the chart when the magnet is energized. Fig. 7 shows the method of starting the synchronous motors 19, 24 in phase.' The positive and negative direct-current leads 50, 51 supply current to the field coils 60, 63 of the motors 19, 24, and to the variable-speed, shunt-wound motor 52 and the regulating-rheostat 53. The shaft of the motor 52 also carries an inverted rectifier consisting of two rings 54, 55, supplied with current by brushes connected to the leads 50, 51, and a commutator 56 having a plurality of segments each connected to the adjacent segments through suitable resistances. The two rings 54, 55 are connected to the commutator at diametricallyopposite points. This gives a two-phase current on the four wires 57<1> leading to the motors 19, 24. If the motor 52 be started slowly, and gradually quickened by the rheostat 53, the frequency of the two-phase current is gradually increased, and the two motors 19, 24 will rotate in synchronism and in the same phase. When the brush 12 engages the segment 17, current flows from the lead 51, brush 16, ring 15, segment 17, and the brush 12 to the magnet 32 and the lead 50.