Patent GB-514177-A (GB)
Title: Improvements in or relating to driving mechanism for the production of rotational movements limited to predetermined angles of revolution or continuous rotational movements, in particular for cinematograph apparatus
IPC: G03B19/18
Filed: 1938-04-28
Abstract: 514,177. Control of motors ; kinematograph cameras. SIEMENS & HALSKE AKT.-GES. April 28, 1938, No. 12747. Convention date, April 28, 1937. [Class 38 (iii)] [Also in Group XX] Travelling to predetermined limits. - Rotary movement produced by an electric motor is controlled so as to be limited to one rotation or a definite part thereof, or to be continuous, by the co-operation with a locking member of a main pawl, and of an auxiliary pawl which may be left in an operative condition or may be held in an inoperative position, the current supply to the motor and the operation of the pawls being controlled by an electro-magnet; the pawls &c. may be applied to an electromagnetic motor which may be used in conjunction with a kinematograph camera for making single exposures or a kinematographic series. As shown, the running period of a motor comprising electro-magnets 1, 2, and an armature 13 is controlled by a main pawl 17 and an auxiliary pawl 21, the pawl 17 being carried by the pivoted armature 15 of an electro-magnet 14. When the magnet 14 is energized, the armature 15 closes contacts 19 for the magnets 1, 2, and raises a locking projection 17a on the end of the pawl 17, from a notch in a disc 18 forming part of a locking member on the shaft 5 of the armature 13, thereby permitting rotation of the armature. The pawl 21 is biassed about its pivot 20 by a spring 23, and has an arm 21b engaging a lateral extension 17b of the pawl; if the pawl 21 is not held, the arm 21b follows the movements of the extension 17b and a locking projection 21a enters the path of a projection 22a on the rim of a disc 22 also forming part of the locking member secured to the shaft 5, thus stopping the shaft when the projections 21a, 22a engage. Such movement of the projection 21a is at first delayed by the engagement between an extension 21c, flexibly connected thereto, and a hub 24a on the shaft 5, and the hub 24a is partly cut away to permit completion of the movement of the projection 21a in time for engagement with the projection 22a. Movement of the armature 15 from the magnet 14, if the energization is of short duration, is delayed, by by engagement between the rim of the disc 18 and the projection 17a, until the projetcion enters the notch. For continuous rotation, the pawl 2L is held inoperative by the previous manual adjustment of a pin 27, on a rotatable disc 26, into a position such that it engages an arm 21e formed on the pawl. Rotation of the armature then continues so long as magnet 14 is energized, and is stopped by the engagement of the projection 17a with the notch in the disc 18 after de-energization of the magnet 14. Further notches and projections may be provided on the locking member, if the rotation is to be terminable after part of a revolution, and the locking member may be carried by a shaft driven through gearing at a speed different from that of the motor shaft. The shaft 5 may carry a bevel wheel and a toothed wheel respectively driving the driving shaft of the film feed mechanism and the shutter shaft, in such manner that all the shafts have the same angular velocity.