Patent GB-219690-A (GB)
Title: Improvements in devices insuring in a continuous and automatic manner the synchronism between a gramophone and a cinematographic projection machine
IPC: G03B31/00
Filed: 1924-07-23
Abstract: 219,690. Robimarga, L. July 26, 1923, [Convention date]. Combined working of gramophones with kinematographs.-In apparatus for synchronizing a kinematograph with a gramophone, one of the machines, preferably the kinematograph, is driven through change-speed gear which is electrically controlled by currents periodically transmitted from the other machine. Fig. 1 shows the driving-mechanism of the kinematograph, in which the main shaft 7 is driven through a pinion 13 by a wheel 11 fast on a spindle 10. Two wheels 19, 20, loose on the same spindle, gear respectively with pinions 21, 22 on a shaft 4, driven by a pulley and belt 5, 6. The gear ratios are such that the speed of the wheel 19 is slightly higher than that of the wheel 20. The wheel 11 is normally driven by the wheel 19 through an intermediate disc 27, which on the one side carries a pawl-lever 25, Fig. 3, engaging with a ratchet 23 fixed to the wheel 19, and on the other side has a projection 29 adapted to engage a projection 30 on the wheel 11. The latter also has a ratchettoothed crown-wheel 31 fixed to it, on which bear spring-pressed pawls 32 projecting from the wheel 20. When the wheel 11 is being driven by engagement of the lugs 29, 30, the teeth of the wheel 31 slip under the pawls 32. A projection 36 mounted on the armature of an electromagnet 38, normally projects into the path of the end of the pawl-lever 25. The magnet is energized at predetermined intervals (corresponding to the passage of a given number of pictures through the projector, and, normally, to each turn of the wheel 19), bv the closure of contacts at the gramophone. Fig. 4 shows the circuit arrangements when two turntables working alternately are employed, fixed contacts 48<1>, 48" coacting respectively with con. tacts 43<1>, 43<11> moving with the turntable spindles. Assuming that the turntable associated with the contact 43<11> is in operation, the other being at rest, the action is as follows. When the contact 43<11> meets the contact 48", the magnet 38 is energized, and the stop 36 is thereby withdrawn. Shortly after this occurs, if the two machines are in synchronism, the lever 25 moves round beyond the stop 36, and the drive of the kinematograph proceeds with the speed unchanged; the contacts 43<11>, 48<11> are opened after a short interval, and the stop 36 returns to the normal position. If, however, the kinematograph is running too fast, the lever 25 strikes the stop 36 before the circuit closure occurs, and is lifted, declutching the driving disc 27. The driving of the wheel 11 is then taken up for a time by the more slowly moving wheel 20. The film therefore gradually loses its lead, during one or more turns, until the normal condition is restored. A pointer 17, geared to the shaft 7, and moving over a dial, indicates the number of pictures projected. A corresponding indicator is connected to the gramophone, and by this means the machines may be. restarted in synchronism should the film break.