GB333255A - Fire preventing means for motion picture projecting machines - Google Patents

Abstract

333,255. Withers, J. S., (Sentry Safety Control Corporation). May 8, 1929. Kinematograph apparatus. - Ignition of the film in a projector is prevented by including in the lamp circuit a switch which is biassed to open on the failure of the current in the motor-circuit. The arrangement shown in Fig. 1 comprises two projectors having motors 6, 7 and arc-lamps 13, 12, respectively. The motors are fed in parallel from mains 4, 5 provided with a fuse 8 and are independently controlled by switches 9, 10. The arcs 12, 13 are in series with a D.C. generator 11 and are independently controlled by switches 14 - - 17. The generator circuit is controlled by a switch 18 biassed to open by a spring and closed by the energization of a solenoid 20 when included in the mains circuit bv the switch 19. Failure of the mains service to the motors allows .the generator circuit to be broken and so extinguishes the arcs. In a modification the solenoid may be arranged in series with each of the motors and is arranged to control the generator for each arc. In a further modification, the motors may be arranged in series with each other and with the solenoid which controls a common generator supplying all the arcs, switches being provided to shunt the motors and arcs when required.