Radiation imagery chemistry: process – composition – or product th – Color imaging process – Intensifying
Patent
1993-11-26
1995-08-15
Le, Hoa Van
Radiation imagery chemistry: process, composition, or product th
Color imaging process
Intensifying
430394, 430414, 430417, G03C 1100
Patent
active
054418534
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of making stable photographic colour prints and particularly to making such prints with photographic materials that contain low levels of silver halide.
There have been many proposals to reduce the amount of silver halide employed in photographic colour materials and colour print materials in particular. One preferred method is to use the so-called redox amplification processes.
Redox amplification processes have been described, for example in British Specification Nos. 1,268,126, 1,399,481, 1,403,418 and 1,560,572. In such processes colour materials are developed to produce a silver image (which may contain only small amounts of silver) and then treated with a redox amplifying solution (or a combined developer-amplifier) to form a dye image. The developer-amplifier solution contains a reducing agent, for example a colour developing agent, and an oxidising agent which will oxidise the colour developing agent in the presence of the silver image which acts as a catalyst. The photographic material used in such a process may be a conventional coupler-containing silver halide material or an image transfer material containing redox dye releasers. Oxidised colour developer reacts with a colour coupler (usually contained in the photographic material photographic material) to form image dye. The amount of dye formed depends on the time of treatment or the availability of colour coupler rather than the amount of silver in the image as is the case in conventional colour development processes. Examples of suitable oxidising agents include peroxy compounds including hydrogen peroxide and compounds which provide hydrogen peroxide, eg addition compounds of hydrogen peroxide; cobalt (III) complexes including cobalt hexammine complexes; and periodates. Mixtures of such compounds can also be used. A particular application of this technology is in the processing of silver chloride colour paper, especially such paper with low silver levels.
Photographic paper for redox amplification processes can be made with increasingly low levels of silver halide. When the level is small enough the density of the developed silver is barely noticeable in the finished print. However over a period of time the undeveloped silver halide remaining in the paper tends to print out (ie the silver halide is reduced to visible silver image) non-uniformly due to the non-uniform nature of exposure by adventitious light. This non-uniform printout does tend to be noticeable when viewing the print.
According to the present invention there is provided a method of making a photographic colour print using a photographic colour material containing low levels of silver halide characterised in that, halide is caused to print out uniformly.
The exposure can be at any stage after which further imagewise image formation can occur. This will be, for example, when any developer has been removed by washing or inactived by a stop bath.
The uniform silver image, in contrast to the non-uniform image normally produced by print-out over a period of time, is not noticeable when viewing the print. The non-uniform exposure to light occurs because of the varied light conditions, degree of shading falling on different parts of the picture at different times in its history, etc. Under normal processing lab arrangements the prints are placed in packaging for return to the customer very soon after coming off the "production line" under ordinary room light conditions.
In a preferred embodiment the uniform exposure occurs before the print is delivered to the customer. It is convenient if the uniform exposure means is built into the processing machine used to make the print.
The uniform exposure is preferably accomplished in the processing apparatus using appropriately mounted exposure means such as tungsten bulbs or fluorescent tubes. Clearly no exposure of the photographic material should occur before the development and/or amplification has fully taken place. Such apparatus is known from the processing of reversal films including reversal colour
REFERENCES:
patent: 5210007 (1993-05-01), Texter et al.
Fyson John R.
Willis Roland G.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
LandOfFree
Method of making stable color photographic prints does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of making stable color photographic prints, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of making stable color photographic prints will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2180992