DE2450684A1 - Cutter for photographic films and mounting foils - has knive blade and support sheet edges mounted at different angles to the film plane - Google Patents

Abstract

The cutting device for photographic films or mounting foils for reprographic purposes has a knife batten, a support sheet and a knife with the knife set at an oblique angle (ALPHA) to the film, which is equal to or less than the angle of incidence of a point light source. The support sheet edge (4) is cut away at an angle which is less than the cutting angle (ALPHA) of the knife blade. Typical angles to the horizontal are 50 deg. for the support sheet, 40 deg. for the sheet edge, and 10 deg. to the vertical for the sides of the blade support.

Description

Ing.Hermann Kümmerl Laborgerätebau, 8500 Nuremberg

Cutter for photographic film material and mounting foils for reproduction purposes

The invention relates to a novel cutting device for photographic film material and for mounting foils, such as they are particularly needed for offset printing.

Cutting a film or foil to the exact size is not a problem in itself. There are numerous for this Facilities *, the problem with which the invention busy, arose from a special requirement. For transferring the cut film to a Light-sensitive carriers can practically only be used with point light, as scattered light, also in connection with Punctual light, especially when exposing smooth grid surfaces, If you look at a film that is provided with straight edges in the usual way, you get restless surface parts the light-sensitive substrate under illumination by point light, it is easy to see that

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a shadow zone must form behind the cutting _{edge, which disturbs the reproduction o} The object of the invention is thus to create a cutting _{device that produces cutting edges without disturbing shadow zones o} Each B'ilin cutting device contains a knife strip with the knife edge, a hold-down plate and a cutting knife. The object of the invention is achieved in that the cutting knife is at an angle to the film surface which is equal to or smaller than the angle of incidence of the light and that the edge of the hold-down plate opposite the cutting edge of the knife strip is beveled at an angle which is smaller than that The cutting angle of the knife is _o

For example, if the angle of incidence of the point light is 40, the cutting angle is also 40 or even less, while the edge of the hold-down plate opposite the cutting edge of the knife bar is beveled at an angle of about 15. As a result of the inclination of the knife and the bevel of the Hold-down bar and the possible choice of the Cutting angle, no shadow zone can form on the film edge »

The cutting device according to the invention can still

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continue to improve. In the case of cutting devices and machines, an either upwardly and downwardly movable or a pivotable cutting knife that extends over the cutting width. Such a knife could also be used in connection with the cutting device according to the invention. A much better embodiment can, however, be achieved in a further development of the invention in that a relatively small knife is attached to a knife carriage which can be moved on a running rail transversely to the film to be cut. If you also equip the knife slide with two knives acting in opposite directions, an edge can be cut both when moving from left to right and from right to left without the slide having to be returned to its starting position _{or the like}

A further improvement is that the cutting edge of the knife or knives is not perpendicular, but below at an angle to the edge of the film. A vertical knife hits the entire width of the film edge, one at an angle directed knife theoretically only at one point. The edge of the film bulges when the knife is attached there is no need to fear an inclined position.

Of the two possible inclinations of the knife cutting edge,

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Inclination in the cutting direction and inclination against the cutting direction, the second option is to be preferred »When you place the knife on the edge of the film, you get one upward component that it is at the end of the cutting edge prevents the film from escaping.

The invention will be explained with reference to the exemplary embodiment shown in the drawings Figs. 1 and 2 show the basic principle of the invention, Fig.

an enlarged fragmentary section of FIG _o is 1, Fig. 3 is a cutting knife assembly, Fig. 4 is a cut edge of a film, Fig. 5 a perspective view of the cutting device.

It should be noted that the dimensions shown in FIGS. 1 to 3 are not binding, but that these are dimensions that have proven to be particularly useful in the practical implementation _o It is, to repeat, that is to cut an edge 2 on a film 1 at an angle that is equal to or smaller than the angle of incidence of light. This is achieved by a hold-down plate 4, which is at a small angle to the male connector 3,

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in order to be able to introduce the film 1 _o

The essential thing about the invention is first of all that the cutting plane 5 of the cutting knife is at an angle oc is inclined that is equal to or less than the angle of incidence of light is. So if the film is placed over a layer to be exposed, the incident can take place Light no shadow zone can be formed behind the film edge. That is the main idea behind the invention.

It is now being supplemented by another measure. A precise cut can only be achieved if the cutting edge 2 lies exactly above the edge 6 of the knife strip 3. However, this means that the front edge of the hold-down plate 4 comes to rest over the edge 6 of the measuring strip 3. This is achieved according to the invention in that the front edge 7 of the hold-down device 3 is beveled at an angle which is smaller than the cutting angle oc . In the example, an angle of 15 ° is assumed. In this design, the front edge 7 of the hold-down device 3 can lie exactly above the edge 6 of the knife strip 3 without the cutting process being hindered. Fig. 4 shows a greatly enlarged cross-section through the cut edge 2 of the film 1 ο It can be seen that the wedge effect of the cutting knife creates a slightly curved edge, which because of this

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Through the incidence of light refraction, it also ensures that there are no marks on the cutting edge during exposure can arise.

It was already said that it would be useful to use the knife edge to incline against the cutting direction. An example of this is shown in FIG. 3, with two oppositely inclined Cutting knives 8 and 9. It can be seen from this that the cutting edge 11 forms an angle [i against the cutting direction 10 is inclined, so that when the knife is applied to the edge of the film and during cutting, an outwardly directed Force component gives what, as tests have shown, particularly favorable for achieving a flawless cut edge.

Fig. 5 shows an embodiment of the cutting device which has proven to be particularly useful. The blades 8 and 9 are fixed with the desired angles by bolts 12 to a carriage 13, guided by rollers 14 along a rail 15 is slidably carried by a frame 16 _o to set the exact angular position of the cutting blades 8 and 9 opposite the film edge are the adjusting screws 17 and 18. The slide 6 is covered with a control button for operation with a cap (not shown). The cap is screwed to the screw bolt 19.

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Claims (6)

Claims ( \ y Cutting device for photographic films or mounting foils for reproduction purposes with a knife bar, a
Hold-down plate and a knife, characterized in that the knife (8, 9) is set obliquely to the film surface at an angle (oc) which is equal to or smaller than the angle of incidence of a point light, and that the
Hold-down edge (4) is beveled at an angle,
which is smaller than the cutting angle (oC) of the knife (8.9). 2. Cutting device according to claim 1, characterized in that the edges of the hold-down plate (4) so far as compared to the cutting edge (6) of the knife bar (3) back- ¹
is set that it is immediately behind the cutting edge of the knife (6,8) _o 3 _O cutting device according to claim 2 or 3, characterized in that the cutting knife (8, 9) is attached at the cutting angle (oc) to a knife carriage (13) which can be moved along the cutting edge. 4. Cutting device according to claim 3, characterized in that 609818 / Ü5b4
BATH ORIGINAL that the cutting edge (21) of the knife (8,9) is inclined at an angle (ß>) against the cutting direction _o 5. Cutting device according to claim 3 and 4, characterized in that the knife carriage (13) has two knives (8, 9) the same but opposite angular inclination are attached. 6 ο cutting device according to one of claims 3 to 5, characterized characterized in that the knives (8, 9) have approximately the shape and size of the knives of conventional pencil sharpeners. 609818/0554 Blank page