DE1016120B - Motion picture projector - Google Patents

Description

GERMAN

The invention relates to a motion picture projector, in particular a narrow film projector, in the course of the film Means to compensate for jerky film unwinding are switched on. Well-known moving image projectors of this type use toothed drums for pre-winding, but their use in narrow-film image projectors is increasing is costly. The inherent elasticity of the film tape has also been used for pre-winding by the film was given the shape of a loop between the supply reel and the picture stage. Here a stationary roller arranged above the picture window served as a deflection means. In doing so, however, showed Irregularities occurring in the film unwinding have strong repercussions on the gripper. One To avoid this disadvantage, further construction provided a movable roller on a Swing arm was attached, which, controlled by a spring, overcame major disruptions. With this arrangement, too, jams on the supply reel had a disruptive effect on the gripper made it impossible to use spools for long film lengths.

It has also been proposed to use braking means to compensate for jerky movements, z. B. an automatically released brake on one of the rollers that are used to transport the film., Or one To use rocker arm with film guide roller, whose rocking movement is braked in one direction expires. Because of the low drive power that is used with cine projectors such braked auxiliary elements consume a relatively large proportion of the total energy.

You also have one or more roles of this type in the area of the film loop mentioned above arranged movably so that they could partially follow changes in shape of this loop. These roles Either, driven by the film, they were constantly in operation, or they were driven by the drive mechanism of the device kept rotating at all times. This constant running of the rotating and the film tape temporarily rubbing masses is also in contradiction to the current requirement, to keep the energy requirement as low as possible. In addition, with these arrangements, the footage continuously stressed by friction between the rollers and the film surface.

The invention is based on a motion picture projector, in particular a narrow film projector a roller attached to a swing arm and arranged in the prewinding loop for maintenance purposes the pre-winding loop and eliminates the disadvantages listed by the fact that according to the invention with this Roll a drive member is rotatably connected, which only determines the loop minimum size

Applicant:

Steatit-Magnesia Aktiengesellschaft,
Lauf / Pegnitz

Heinz Berkenhoff, Cologne-Holweide,
has been named as the inventor

The end position of the roller is in drive connection with the device drive mechanism. Only granted in this end position while the drive member gives the film an additional forward pulse by means of said roller in the case of intermediate positions, the elasticity of the loop and the possibility of swinging out the swing arm for they are sufficient to absorb small deviations from the mean running speed of the film, without having to use the drive mechanism of the device for this purpose. In the drawing an embodiment of the subject invention is illustrated.

The film 1 is taken from the supply reel 2 in the form of a loop 3 around the rollers 4 and 5 between the picture stage 6 and counter stage 7 past the picture window 8 to the take-up reel, not shown in the figure guided. The film is moved step-by-step by a gripper 9 for compensation the propulsion shocks wraps the film loop 3 around the roller 4 so loosely that the inherent elasticity the film loop 3 is not affected by the roller 4. Therefore, the loop 3 oscillates, which is the aspiration has to cushion, in the rhythm of the frame rate and compensates for the switching shocks. The role 4 is applied to one end of a shaft 10 centrically and twist-proof, while the other End of a friction disc 11 carries secured against rotation. A lining 16 of the roller 4 causes a Increase in friction. A swing arm 12, whose axis of rotation 13 is fixed relative to the device, carries the Storage for the shaft 10. It is held in a vertical position by its weight. As part of It is also a matter of the invention to hold the swing arm 12 in its normal position by means of a spring can. A pulley 14 set in constant rotation by the gripper motor is in the oscillating track of the arm 12 arranged so that the arm 12

705 597/235

Claims (5)

sufficiently far pivoted friction disc 11 can be coupled to the pulley 14. The rubber drive rope 15 increases the friction. The mode of operation of the arrangement according to the figure is as follows. As a result of the tension of the film strip 1 caused by the gripper 9, the supply reel 2 starts rotating. As a result of the great weight (especially with long films) of the fully wound supply reel 2, this rotation is temporarily not uniform. There are shocks that pull the film loop 3 together and possibly move the swing arm 12 clockwise out of its vertical rest position via a roller 4. Slight shocks are compensated for by the effort of the swing arm 12 to return to the rest position. On the other hand, stronger impacts press the friction disc 11 against the rope disc 14 rotating in the direction of the arrow, whereby the friction disc 11 and the roller 4 are set to rotate in a clockwise direction. The roller 4 driven for a short period of time then pulls the film 1 from the supply reel 2 so that the loop 3 is enlarged. If it has - possibly after repeated repetition of this additional drive for the film - regained its size and position corresponding to the average running speed, the arm 12 falls back into its rest position due to its weight. The exemplary embodiment described reveals the following advantages in detail for the arrangement according to the invention: The film is spared since the loose loop normally does not touch the control element 4 or only touches it very slightly. At no point in the compensation mechanism are braking means used on purpose, only driving means are used. These funds are only used when really needed. This means that drive energy is used sparingly. The organ of the compensating mechanism (roller 4) that touches the film in the driving sense does not attack the film in a sudden or jolt-like manner, but rather pulls the film strip quickly and without any significant change in direction as a result of the interposition of elastic links. Since the tape material is best able to withstand pure tensile stress, the film is also spared in this sense 1. Motion picture projectors, especially narrow-film projectors, with arranged in the pre-winding loop, Roll attached to a swing arm for maintaining the pre-winding loop, characterized in that that with the roller (4) a drive member (11) is rotatably connected, which only in the the end position of the roller with the device drive mechanism in drive connection, which determines the minimum loop size stands. 2. motion picture projector according to claim 1, characterized in that the roller (4) together with a friction disc (11) on a shaft (10) is attached to the swing arm (12) is arranged, which is deflected in such a way in the event of large changes in shape, of the film loop (3) that a temporary coupling of the friction disc (11) with one of the Motor of the device driven device part (14) takes place. 3. motion picture projector according to claim 2, characterized in that the roller (4) with a coating is provided to increase the friction between the film and the roll. 4. motion picture projector according to claim 2 or 3, characterized in that the swing arm (12) held by spring action in the rest position that determines the maximum size of the film loop will. 5. motion picture projector according to claim 2 or 3, characterized in that the swing arm (12) is kept in the resting position by its weight. Considered publications:
German patents Nt. 496,682, 643,428;
U.S. Patent No. 1,958,152. 1 sheet of drawings 7Oi 697 /? 35 9.57