Optics: motion pictures – Camera and/or projector drive mechanisms – With film engaging claws reciprocally driven to engage film
Patent
1991-04-19
1993-07-06
Hayes, Monroe H.
Optics: motion pictures
Camera and/or projector drive mechanisms
With film engaging claws reciprocally driven to engage film
226 62, 226 67, 226 68, 226 70, 226 71, G03B 122
Patent
active
052258602
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a film transport mechanism for a motion picture camera.
DE-PS 36 43 594 teaches a film transport mechanism in a motion picture camera that moves the film, perforated along both edges, to be transported stepwise past a gate with the aid of transport claws in steps, said claws, together with the corresponding transport drive, being located on both sides of and symmetrically with respect to the central plane running vertically along the center of the film. The transport claws are moved by the respective transport drives in such manner that the tips of the claws traverse an elongated, closed curve which enters the film travel plane at one end and leaves it again at the other end.
For this purpose, each transport drive has two shafts, each coupled with a crank. The end of one crank forms a pivot at which the transport claw strap is articulated. In the middle portion of the transport claw strap there is likewise a pivot at which a connecting rod is articulated, said rod being connected with the end of the other crank. The two shafts connected with the cranks are connected by a rotating toothed pulley with a main drive shaft with the transport drives opposite one another being driven by the same common drive shaft which is mounted in one bearing on either side of the central plane.
In addition, a crank drive for a locking claw is provided, said drive being connected with the shaft driving the end of the transport claw strap. The angular displacement between the two cranks on the common shaft is selected so that the locking claw is outside the film plane when the transport claw tips are advancing the film.
One disadvantage of the known film transport mechanism consists in the fact that in order to change the advancing step and the angular relationships, in other words, the depth of penetration and path of the tips of transport claw, considerable design modifications are required and the length of the stroke is relatively large so that the film, as a result of engagement of the transport claw tips in the perforation holes, is moved along a curved path which results in a so-called "sawing action" produced by the sliding of the transport claw tips in the film perforations.
A claw transport is known from DE-PS 385 819, said transport consisting of two cranks, of which the first crank acts on one end of a rod with the claw pins, while the second crank is connected by an intermediate lever with the other end of the rod. Both cranks are coupled together by gears. In this known claw transport, considerable design modifications are required to change the depth of penetration and the path of movement of the claw tips in order to achieve a depth of penetration of the claw tips which is as small as possible yet sufficient depending on the local conditions.
The goal of the present invention is to improve a film transport according to the species in terms of its adaptability to local conditions.
The solution according to the invention provides a film transport mechanism which can be adapted simply to local conditions so that, with minor changes, different stepping and pulling angle relationships and a different stroke length are made possible and easy balancing of the transport is ensured, with limited space requirements in the vicinity of the film path being achieved as well.
The improved adaptability of the film transport mechanism to local conditions results in an extremely high resistance to wear and a low noise level of the film transport, making possible different step and angle relationships with minor conversion measures and avoiding balancing problems. In addition, a working curve for the claw is achieved which can be changed with minor technical means, the tips of said claw penetrating shallowly yet sufficiently into the film perforations and, at the end of the stroke, being pulled in the shortest possible time nearly perpendicularly out of the film perforations.
The film transport mechanism, limited mechanical means, permits different step and angle relationships, for example, advancing two,
REFERENCES:
patent: 1388886 (1921-08-01), Pittman
patent: 1891585 (1932-12-01), Vinten
patent: 1912535 (1933-06-01), Mitchell
patent: 4402581 (1983-09-01), Bauer
patent: 4896960 (1990-01-01), Williamson
Arnold & Richter Cine Technik GmbH & Co.
Hayes Monroe H.
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