DE1090082B - Device to compensate for color distortions when copying and enlarging color negatives or color slides - Google Patents

Description

The invention relates to an apparatus for copying or enlarging with one sentence of correction filters in the subtractive primary colors.

It is known that continuous filtering can be achieved by introducing a medium density filter more or less far into the beam path of the copier and compensating for the uneven illumination that occurs with a diffuser.

This device has the disadvantage that it cannot use a very high color yield, otherwise, in spite of the diffuser, a locally uneven coloration of the copy will result. Also can in the case of very high enlargements, even when using a medium density filter, an uneven picture Illumination of the image field arise.

It is also known, a change in the effective filter transparency resulting from the adjustment of the filter to compensate by setting a diaphragm in the opposite direction. This arrangement is used however, gradient density filters which make them cumbersome.

It is also known per se, color copies by means of to produce three partial exposures and the duration of each individual partial exposure through slits to steer in a control band. This comes in handy only for making very large copies of a single template in question, since the control belt is specially slotted for each template appropriate length must be provided.

According to the invention in a device for copying or for enlarging with one sentence of correction filters in the subtractive primary colors that occur in the known devices This avoids tend disadvantages that a uniform, stepless color gradient of the highest filter Color density close to zero is achieved by using a uniform in the highest desired color density colored transparent material a comb-like cut in the direction of movement of the filter Has shape.

Conveniently, the set of three cylinder-shaped correction filters is concentric around the Beam deflecting mirror stored and on the front of the device by levers or control buttons manually adjustable.

It is advantageous here to have one filter segment running in the opposite direction to the correction filter for compensation the one-sided color density in front of or behind the same.

An exemplary embodiment of the subject matter of the invention is described below. It shows

Fig. 1 the color head of the device in section,

Device for compensation
of Farbyej forgeries beini
and enlarging color negatives
or color slides

Applicant:

Lotte Veit, née Gänshirt,
Munich 23, Bismarckstr. 2

Anton L. Veit, Munich,
has been named as the inventor

Fig. 2 shows the front view of the color head with adjustment knobs and setting dials,

3 shows a development of one of the three correction filter rings with the associated counter-rotating filter segment.

Corresponding parts are denoted by the same numbers in all figures.

The device is constructed as follows: The three filter rings 1, 2, 3 in the subtractive colors yellow 1, Purple 2 and blue-green 3 lie in the horizontal axis concentrically around the beam deflecting mirror 4, the deflects the light from the projection lamp 5 onto the diverging lens 6 via the condenser of the enlarger. Above the diverging lens 6 is an opal disc 7 attached, which covers this and distributes the filtered light evenly. Between the projection lamp 5 with its optical system and the beam deflecting mirror 4 is a heat filter 8, which protects the mirror and the three filter rings from the heat of the projection lamp. Inside or on the outside of each of the three correction filter rings 1, 2, 3 are the opposing ones Filter segments 9, 10, 11, which when the correction filter is reset by a driver are moved out of the beam path. There are three control buttons on the front of the color head 12, 13, 14 attached for setting the correction filters. Above or below are the scales 15, 16, 17 for the adjustment of the correction filter rings 1, 2, 3 attached.

009 609/133

For the construction of the filter rings 1, 2, 3 there are various possibilities. A very suitable version consists of one in the corresponding filter color and the desired filter density colored plastic disc (e.g. Plexiglas) with a completely uniform progression of the color density is achieved by the fact that the colored plastic disc, as shown in Fig. 3, like a comb in the longitudinal direction was very finely toothed, punched out and bent into a cylinder jacket. This cylinder jacket is held in its shape by metal rings on the end faces.

Another possible implementation is that a Color film is cut in the highest desired color density and placed between two glass cylinders or that the fine-toothed pattern is printed on a transparent film and placed between glass.

The cylindrical shape for the correction filter. Is therefore chosen because this saves a lot of space and there are structural advantages in operation the filter result. The correction filters could, however, also be in the form of a planar, rectangular one Filters can be selected, which one, similar to a slide, through the beam path of the light source pushes and thus achieves an infinitely variable filter setting.

It has proven to be useful to use the correction filter rings 1, 2, 3 and the opposing filter segments 9, 10, 11 to be made from a filter material, as it is commercially available under the name "Density 200".

The color head described here has the advantage that it can be placed on any existing enlarger can be, whereby only the normal dome of the device has to be removed.

Claims (4)

PATENT CLAIMS: 1. Device for copying or enlarging with a set of correction filters in the subtractive primary colors, characterized that a uniform, stepless color gradient 'the filter from the highest color density to approximately zero is achieved by a uniformly colored in the highest desired color density transparent material a comb-like cut in the direction of movement of the filter Has shape. 2. Device according to claim 1, characterized in that that the set of three correction filters in a cylindrical shape is mounted concentrically around the beam deflecting mirror and on the The front of the device is manually adjustable by levers or control buttons. 3. Apparatus according to claim 1, characterized in that one filter segment rotates in opposite directions arranged in front of or behind the correction filter to compensate for the one-sided color density is. 4. Device according to claims 1 to 3, characterized in that the light source, correction filter, Diffuser and possibly a counter-rotating filter segment in a color head are united, the on a copier of conventional design, containing imaging optics, negative stage and enlarging frame or paper holder, can be attached. . . - Considered publications:
German Patent No. 897 654;
French patent specification No. 1 162 909. 1 sheet of drawings © 009 609/133 9.60