Photocopying – Projection printing and copying cameras – Multicolor picture
Patent
1995-03-02
1997-06-17
Grimley, Arthur T.
Photocopying
Projection printing and copying cameras
Multicolor picture
355 34, 355 71, G03B 2732, G03B 2746, G03B 2758
Patent
active
056402260
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a device for colour photograph printing.
One of the most widespread processes for printing colour photographic images envisages that a negative or slide bearing the image to be printed be passed through by a light beam which has itself already passed through colour filters so that the beam contains predetermined primary colours which are subsequently localized by a lens onto photosensitive paper of known type. The particular colour percentage sensitivity of the paper depends on the kind of paper used: some are sensitive to red, green and blue (used in additive synthesis), others to yellow, magenta and cyan (used in subtractive synthesis). The actual percentage of sensitivity can vary within a range of similar paper: for example, it might be 30% red, 25% green and 45% blue.
The light beam is first prepared vis a vis the colours desired and the appropriate filters selected, and after it has crossed the film or slide, reaches the paper. Chromatic relationships must be extremely precise in order to obtain a faithful and exact colour reproduction on the paper.
BACKGROUND ART
In known-type processes the light beam colour percentages reaching the paper are greatly influenced by the type of negative support used and the exposure quality of the image contained on it: the light beam is in fact strongly chromatically and densitometrically affected by the type of support, so that results can vary greatly.
This problem is at present resolved by providing a considerable number of colour filters to filter the light coming from the source before it reaches the negative support. The drawback with this process is that for each type of negative support suitable filters are required and have to be painstakingly selected.
In modern enlargers the selection of the correct filters from the set mounted on the enlargers is made by analyzing the beam after said filters have been selected, which is usually done automatically, and making a final choice after some test runs of this nature. Amateur photographers, however, usually possess non-automatic devices and thus have to try out several different filter combinations before obtaining a satisfactory result.
A principal aim of the present invention is to obviate the above drawbacks by providing a device which permits of obtaining a light beam having a chromatic composition that is not influenced by the quality and type of negative support bearing the image to be developed.
An advantage of the device is that it obtains the desired result while remaining very simple and economical.
DISCLOSURE OF INVENTION
The aims and advantages are achieved by the device of the invention, as it is characterized in the claims that follow, which comprises a light source generating a beam which crosses a negative support bearing a photographic image to be printed, and which localizes the image on to photosensitive paper of a known chromatic sensitivity, wherein at the point of image inversion a circular filter exhibiting coloured segments of equal area is disposed perpendicularly to the lens optical axis, said filter having a dealigned axis in relation to the optical axis, with an interaxis between the two axes being adjustable.
Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of a preferred but non-exclusive embodiment here illustrated in the form of a non-limiting example in the accompanying drawings, in which:
FIG. 1 shows a diagram of the device of the invention;
FIG. 2 shows an enlarged schematic view of the filter of the device.
The device comprises a light source 1 constituted, for example, by a normal light bulb such as those present in all devices of this type. The light source 1 generates a beam which crosses a support 2, for example a negative, bearing the image to be printed.
The device further comprises a known-type lens, schematically denoted by 3, by means of which the light, having crossed the support 2, is focused on photosensitive paper 4.
A filter 5 is arranged a
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patent: 3759155 (1973-09-01), Bestenreiner
patent: 4087174 (1978-05-01), Nishikawa
patent: 4264193 (1981-04-01), Oonishi et al.
patent: 4522491 (1985-06-01), Ingalls et al.
patent: 4623245 (1986-11-01), Yu
patent: 4894760 (1990-01-01), Callahan
patent: 5471344 (1995-11-01), Sugawara
Grimley Arthur T.
Ingenia S.r.L.
Kerner Herbert V.
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