Patent GB-191114503-A (GB)
Title: Improvements in and relating to the Transmission of Pictures of Moving Objects.
Inventor: SINDING-LARSEN ALF
IPC: H04N5/073
Filed: 1911-06-19
Granted: 1912-03-21
Abstract: 14,503. Larsen, A. Sinding-. June 20, 1910, [Convention date]. Optical apparatus.-In apparatus for transmitting pictures of moving objects to a distance, synchronism between the devices for splitting up the picture at the transmitter and recomposing it at the receiver is ensured by arranging them to vibrate with the same natural free period. Fig. 3 shows the transmitter in which the elements of an image formed by a lens 1 are caused to fall on a lens 4 in succession along a zigzag line in the usual way by allowing the light to be reflected from two mirrors 2, 3 vibrating about perpendicular axes, one mirror 2 vibrating much more rapidly than the other. The transmitter may be evacuated. At the receiving-station, light from a point the illumination of which is proportional to that of the orifice 4 is reflected at two mirrors similar, and vibrating similarly, to those at the transmitter, and is then observed directly or caused to fall on a screen, or is photographically recorded. The mirrors vibrate in their natural free period, and the vibrations are electro-magnetically maintained; the more rapidly vibrating mirror 2 is unpolarized so as to be actuated by interrupted current, and the other is polarized so as to be actuated by alternating current. The mirror 2 comprises a silver-plated iron sheet playing between the poles of an electro-magnet 9 and suspended on a piano-wire 8, its.free period being adjusted by varying the tension of the wire. The mirror 3 is pivoted on pins 10 and is spring-controlled, and on its back is secured a permanent magnet 11, the poles of which are situated between the poles of two electro-magnets 12. The magnets of the rapidly vibrating mirrors at the two stations are connected in series and are supplied with an intermittent current of the same period as the natural vibration period of these mirrors, produced either by means of the vibrating bodies themselves or by a separate vibrator. The magnets of the slower mirrors are supplied with an alternating current of the same period as their own, either from an alternating-current generator or from a battery and rotating commutator. Preferably all the magnets are connected in series, and the interruptions for operating the rapid mirrors are superimposed on the alternations for operating the others. The light is transmitted directly along an internally polished tube 5 preferably of silver or other metal with a lower refraction coefficient than air, which may be filled with hydrogen or other inert gas or evacuated. The rays are rendered as nearly parallel as possible by means of the lens 4 or the conical device shown in Fig. 6. The tube may be used as a conductor for the synchronizing-current, an earth return being employed. The light from two or more points of the image may be transmitted simultaneously to increase the brightness of the picture. The receiver may be adjusted from the sending station by means of slow-acting ratchet mechanism controlled by prolonged impulses superimposed on the synchronizing-currents. Fig. 10 shows an arrangement of prisms for simultaneous transmission in both directions along the tube. The Specification as open to inspection under Section 91 (3) (a) describes also the use of (1) a string of some suitable material, such as quartz, instead of a tube; (2) cylindrical mirrors, and a single mirror vibrating simultaneously about two perpendicular axes, the mirror being made concave to replace the object lens, and (3) mirrors formed of separately oscillating strips. Another method is also described in which, instead of the image moving over the orifice, the orifice is moved over the image by forming it at the end of a tube which is mounted so as to vibrate about two rectangular axes, its vibrations being controlled by bodies having a marked natural vibration period. This subject-matter does not appear in the Specification as accepted.