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They provide first by lateral webs that the film is exactly centered in the machine direction. A first sprocket (Vorwickelrolle) pulling the film from the reel, in the upper drum fire protection lies. For coils and plate towers operating separate motors provide continuous film feeding. It follows the first, upper film loop as a transition from the continuous movement, to stop-and-transport through the Pulley .
Above this is the loop Filmriss switch , which is raised when a film is jammed in the crack between Vorwickelrolle film and movie channel. This then drive motor and exciter lamp is switched off, also there is a light damper closes before the picture window. As previously flammable nitrate film was used, was a fire switch is provided which is biased by a separate nitrate film loop. Started the fire by running a copy, this loop also burned and caused the fire switch. It occurred the same consequences as a crack in the film switches; additional cases were still flaps raised before the projection of the projection booth and show openings.
In the movie channel that can be opened for loading (film or slide door), the film is between film track with Sammetauflage and two Andruckkufen out. Through the picture window of the mask, a matching image portion is illuminated by the light from the lens mount and clamped lens projected.
For cooling, including the film in the movie channel is partly a cooling water supply available with inlet and outlet. Alternatively or in addition to the cooling water , some models have a picture window between the lamp and arranged heat-absorbing filter or an air cooling of the picture window.
After the film is run through the carriage, where he was projected image by image, followed by another film loop, then another sprocket (Nachwickelrolle) which is then placed in continuous motion. To insert a film, the projectionist to keep the "principle of the longest path."
After the lower loop is the optical sound arranged. The film first passes through a brake roller with rubber pressure and reaches the capstan , where the soundtrack of the clay lamp illuminated by means of optical gap and the photocell is scanned. The capstan is connected to a flywheel and is used by passing it puts film wrapping around in rotation. The film then passes through a spherical roller, which ensures tight film location in the sound device, and is passed over the toothed Nachwickelrolle, where the lower pressure roller prevented from jumping out of the perforations in the lower drum fire. The lower coil axis driven winds here the film onto a reel (fishing reel, open reel) and a Bobby (a small plunger, formerly made ??of wood, now made ??of plastic).
All gear wheels and the gripper system (Pulley) are synchronously coupled. Pulley, sleds and masks as a whole are vertically movable in order to be able to adjust the image as the film. Through this frame line adjustment , the demonstrators - if the film was loaded incorrectly - ensure that the entire film frame, but not between two images is shown lying framing. The runners of the sled pressure is adjustable to compensate for differences in the mechanical part of a film material (eg, waves, kinks, splices) and fix the other hand, the image during his arrest safely. The rotary shutter must be adjusted to the shift in their temporal position roll so that the beam only when they stopped the movie releases. Further increase their wings on the cut-off frequency to the extent that no flicker is perceived.
Before loading the film of the hand wheel is pressed until the sprocket wheel is straight in repose. Now the film is inserted so that exactly one frame in the image window. Since the projector needs to gather speed for a certain period, usually not a movie screen, but an image of the boot band is positioned in the picture window. To make sure that it comes between the loaded image and the first actual picture of the act no shift of the image position (it is in fact usually black band with no visible frame line immediately before the first actual picture), the projectionist should conduct an appropriate visual inspection. This can be done, for example, that you can run the film by hand on an old Vor-/Nachwickelrolle, on which are markings for framing.
There are 16 ways to insert a 35-mm film. This number of combinations resulting from multiplying
2 possibilities for the direction (beginning or end ? End ? beginning)
2 possibilities for the location of the sound track (or the lateral position of the image)
4 possibilities for the insertion of a single image in the image window (corresponding to the 4 perforations per frame).
Of these 16 possibilities only leads one to immediately correct a projection is at least three other a correction by the image line adjustment possible. In the remaining 12 cases, however, interrupted the show and the movie will be reinserted. The film is loaded correctly, if
beginning of the film in the direction of the projector is running ("heads down")
the sound track is located right in the sight screen
exactly one image is inserted into the picture window
To protect the film are all the roles (and other parts that may come in contact with him or, like the movies, but also the film cracks switches) designed so that only the perforation is in direct contact with these parts. Therefore, in the range of the actual image corresponding depressions are present (see, eg, mapping of the sprockets).
In the rest of the movie channel should always be open and all the pressure rollers. Note you do not, may in particular in the form of radios and flat rubber pressure points that cause interference.
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