DE1237890B - Film camera with leadership role - Google Patents

Description

Film camera with guide roller The invention relates to film cameras with Guide rollers or rollers between the supply reel and the picture window or in the drawn one Filmtrum.

In a roll film camera, the film is usually in the picture window pressed against the picture window by the pressure plate on the back and thus flat held. Adding a glass plate in the picture window is a further improvement the film plan flag possible; However, if the pressure of the rear pressure plate is set too high, Newton rings can form. Because of this, will generally a film channel between the film support rails of the picture window or the glass plate and the rear pressure plate are preferred, the film channel is adapted as closely as possible to the thickness of the film and the protective paper to the Not to complicate film transport unnecessarily and to keep the risk of scratches low.

Especially with longer breaks between the individual recordings and the film does not retain the vibrations that occur when the camera is transported always the position it assumed immediately after the film was transported.

The arrangement according to the invention ensures that the roll film not only transported under tension, but also continuously under Tensile stress is held in the image window. It also increases the magnitude of this tension kept within narrow limits.

According to the invention, a helical spring is arranged in the hollow guide roller, which rests with its outer circumference in the guide roller under spreading tension in a friction-locked manner, its winding direction coinciding with the direction of rotation of the roller during film transport, and the free end or ends of the spring are on the bearing axis of the guide roller held. The helical spring preferably wraps around the stationary bearing axis during the film transport in the sense of a locking mechanism. The guide roller is appropriately provided with a film-slip-reducing coating. The drawing shows an embodiment of the subject matter of the invention, C ZD, namely FIG. 1 shows a vertical section through the rear part of the camera, FIG. 2 shows a cross section through the new guide role, F i g. 3 shows a longitudinal section through the guide roller and FIG. 4 shows a longitudinal section through a second embodiment of the roller.

The film 8 is wound in the usual manner in the supply reel 1 via a deflecting tube 2 into the image window 3 of the camera and from there via a further guide roller 4 onto the take-up reel 5. In the picture window 3 , the film 8 is pressed by a pressure plate 6 which is attached to the rear wall 7 of the camera. The picture window 3 can receive a support glass plate. Between the picture window 3 or the glass plate and the pressure plate 6 , a film channel is formed from e, the thickness of which corresponds as closely as possible to the total thickness of 9 C of the film and protective paper. The guide roller 2 is mounted on its lateral guide bushes 10 and 11 on a fixed axis 9 in the camera. The roller 2 is equipped with a film-slip-reducing covering 12 made of foam rubber or rubber. Inside the roller 2 there is a coil spring 13 with large and small turns. With the large turns, the helical spring 13 lies against the inner wall of the roller 2 with a certain amount of friction; the other end 14 is wound around the axis 9. The winding direction is chosen so that when the roller 2 is rotated, the spring with the windings 14 is tightened on the axis 9 and the spring is tensioned. When a certain frictional torque is exceeded, the roller 2 slides on the spring windings 13, while the windings 14 are stuck on the axle 9 , the spring remaining under tension. When the film pull ceases, the spring expands again and keeps the roller 2 or the film 8 under tension.

In Fig. 4 shows a second embodiment in which the spring is provided with large turns 13 ' in the middle and both spring ends 14 and 15 " are looped around the shaft 9' . In this way, a symmetrical structure is achieved with the same mode of operation.

It is obvious that the new role is not just about keeping things taut of the film in the image window can be used, but wherever possible constant belt tension is intended during the belt movement and also at standstill of the tape should be preserved.

Claims (2)

1. A film camera with guide roller between the supply reel and the image window, d a d u rch g e -k c NNZ c ichnet that a helical spring bears frictionally with its outer circumference in the guide roller under spreading tension, wherein its Wickelrichtuno, with the direction of rotation of the roller in which Film transport coincides, and that one or both free ends of the spring are supported on the bearing axis. 2. Film camera according to claim 1, characterized in that the helical spring wraps around the fixed bearing axis in the sense of a locking mechanism effective during film transport. 3. Film camera according to claim 1 and 2, characterized in that a preferably between the supply reel and the picture window and entrained by the film train roller or roller contains a helical spring, the circumference of which is frictionally applied inside the hollow roller, while the one or more ends of the spring Wrap around the stationary roller axis, the winding direction being selected so that the spring, which acts as a brake when the roller is driven by the film, is tensioned by friction and clamped on the axis. 4. Film camera according to one of claims 1 to 3, characterized in that the guide roller or roller is provided with a coating which reduces the film slip.