DE1916989A1 - Negative frame for guiding the film tape - Google Patents

Description

The invention "relates to a negative frame for guiding the Film tape in playback devices, especially in enlargers, which has a central body with a Image window and a pressure part also provided with a window, the film tape between body and pressure part is inserted and its body is two on opposite sides in the direction of the longitudinal axis of the film tape extending cup-shaped holders, each having a leading edge at its end remote from the body have transverse to the longitudinal axis of the film tape.

Negative frame for guiding the film tape in playback devices, Especially in the case of enlargers, they are provided with holders that are cup-shaped in the guide direction are arranged on both sides of the negative frame extending in the sighting of the longitudinal axis of the film strip.

909845/0987

It is required of the bowl-shaped holders that the Surface of the film tape comes into contact with the surface of the holder as little as possible. Through this is said to be the greatest possible damage to the film tape due to mechanical influences during its advance can be avoided by the negative frame.

It has already been proposed to design the cup-shaped holder so that its profile in that to the longitudinal axis the vertical section of the film tape is stepped. With so constructed cup-shaped holders comes the film tape with the holder surface in contact only with its edge areas. If the negative frame for film tapes of different widths are to be used, several levels must be selected, both for the Manufacturing as well as operationally disadvantageous.

It is also known to design the cup-shaped holder in such a way that the line of intersection ^ every arbitrary, to the longitudinal axis of the film tape perpendicular plane with the inner surface of the cup-shaped holder a continuous, concave curve results. Most of the time, the inner surface of such holders is formed by part of a sphere. This design is advantageous in terms of the wear and tear of the film tape, but disadvantageous for manufacturing reasons, since the mounting of such a holder in the body of the negative frame is complex; and there, especially with one spherical profile, as well as the production of the holder or the relevant tool with difficulties connected is. .

The object of the invention is to create such Design of the cup-shaped holder, which retains the functional advantages of the last-mentioned holder, in which the film tape only has two edges

909845/0987

leads, but at the same time the application of a simple manufacturing technology "enabled in the manufacture of the holder and due to their simple design and assembly is advantageous.

This object is achieved on a negative frame of the type mentioned at the outset in that at least the profile of the surface of the cup-shaped holder bearing the film tape including the guide edge, seen in any plane perpendicular to the longitudinal axis of the film tape, is roughly channel-shaped, for example from an at least one broken or broken one. angled surface is formed, wherein the channel wings open in the direction of the film tape.

The essence of the invention is that the profile do's cup-shaped holder including outer Transverse edge, based on any plane perpendicular to the longitudinal axis of the film tape, of one at least once broken surface is formed, the parts carrying the film tape inclined relative to the plane of the film tape Zo B. are concave. The individual areas of the Middle the broken surface with the aforementioned plane perpendicular to the longitudinal axis of the film strip are advantageously straight.

The object of the invention fulfills the conditions set out in the preceding part of the description retains the functional advantages of the shell-shaped holder of the known type and enables the application a simpler manufacturing technology.

An embodiment of the invention is explained in more detail with reference to the drawing. Show it: ,

5/098 7

Fig. 1 is a longitudinal section through the shown schematically Negative frame with shell-shaped •; 'Holders;

FIG. 2 shows a view in the direction of arrow P according to FIG. 1;

3 shows a section A-A according to FIGS. 2 and

Fig. 4

to 7 differently profiled embodiments shell-shaped Holder,

As is apparent from FIGS. 1 and 2, the negative frames from a central body with ± image window 4 and the presser is J51. formed with window 41st. Both parts clamp the film tape 1. with the longitudinal axis Ijo and thus determine its position at the moment of playback. On both sides of the negative frame, the shell-shaped holders 2_ are connected to the solid body j [.

As can be seen from Fig. 3, the bowl dryer Holder 2_ a channel-shaped cross-sectional profile, approximately in Kind of a wide open V, with the straight line of impact of the two wings practically parallel to the longitudinal axis i £ of the FiImjl band 1. runs. Bas film tape 1. rests on the shell-shaped Holder 2, with part of its edges in points 11., 11 'from.

When the film tape lies loosely outside the shell-shaped holder, as shown in the left half of FIG. 1, it rests on the transverse edge 2p_, the surface of which is V-shaped in the plane perpendicular to the longitudinal axis 1_p_ of the film tape A. Just from the imagination it becomes clear that in this case too the film tape ± is supported on the shell-shaped holder Σ2 or its edge 2o_ only with its edges at two points.

909845/0987

The V - Profile of the cup-shaped holder 2_ is in the direction of the longitudinal axis I ₁ O of the film tape 1, the same, such that each perpendicular to the longitudinal axis of the film tape 1l £ I ₁ z plane. B. A - A, · its inner surface intersects in two straight lines, which are inclined towards the axis of the cup-shaped holder.

4- to 7 show some possible profiles of the cup-shaped Holder 2_ in the sectional view according to Fig. 3. The profile according to Fig. 4- is similar to the profile according to Fig. 3, only the middle part of the body of the cup-shaped holder 2. is omitted.

Figs. 5 to 7 show some further examples of the training of the profiles of the bowl-shaped holder 2 * Here, FIGS. 5 and 6 represent types of construction in which the Pro * Fil cross-section composed of several flat areas is, while according to FIG. 7, the profile of the cup-shaped holder 2_ consists of two slightly curved surfaces.

909845/0987

Claims (1)

Claims Negative frame for guiding the film tape in playback devices, especially in enlargers, which have a central body with an image window and a pressure part also provided with a window, with the film tape between bodies and pressure part is inserted and its body is two on opposite sides in the Has the direction of the longitudinal axis of the film tape extending cup-shaped holder, each on their distal end a leading edge transverse to the longitudinal axis of the film tape, characterized in that at least the profile of the one carrying the film tape Surface of the cup-shaped holder (2) including the leading edge (2o) in any Plane seen perpendicular to the longitudinal axis (1o) of the film strip (1), approximately channel-shaped, for example is formed by an at least once broken or angled surface, the Channel wings open in the direction of the film tape «, 2, negative frame according to claim 1, characterized in that that the profile of the entire holder (2) is channel-shaped. 3. Negative frame according to claims Λ and 2, characterized in that the profile of the holder (2) or its surface is composed of several straight pieces forming a channel. 909845/0987 4- · Negative frame according to one or more of the claims 1 to 3t, characterized in that the holder (2) has a recess in the edge of the channel. 3 * negative frame according to one or more of claims 1 to 4-, characterized in that the channel wings each consist of convex pieces. 31. Mars ^ 69 / Gr 36 909845/0987 -ο Blank page