Radiation imagery chemistry: process – composition – or product th – Regenerating image processing composition – Developer
Patent
1992-08-14
1995-02-07
Baxter, Janet C.
Radiation imagery chemistry: process, composition, or product th
Regenerating image processing composition
Developer
430403, 430373, 430414, 430943, 354320, 354321, 354324, 354338, C03C 530, C03C 531, G03F 302
Patent
active
053874994
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of photographic processing and to apparatus useful therefor.
Conventional colour photographic silver halide materials are processed by a process which includes a colour development step. In this step silver halide is reduced to metallic silver in the light-exposed areas and the oxidised colour developer formed in this reaction then couples with a colour coupler and forms image dye. The amount of dye produced is proportional to the amount of silver halide reduced to metallic silver.
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 to form a dye image. The redox amplifying solution contains a reducing agent, for example a colour developing agent, and an oxidising agent which is more powerful than silver halide and which will oxidise the colour developing agent in the presence of the silver image which acts as a catalyst. Oxidised colour developer reacts with a colour coupler (usually contained in the 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, cobalt (III) complexes including cobalt hexammine complexes, and periodates. Mixtures of such compounds can also be used.
Since the amplifying solution contains both an oxidising agent and a reducing agent it is inherently unstable. That is to say unlike a conventional colour developer solution, amplifier solutions will deteriorate in less than a few hours, especially less than one hour, if left in a sealed container. The best reproducibility for such a process has been obtained by using a "one shot" system, where the oxidant is added to the developer and the solution mixed and used immediately (or after a short built in delay) and then discarded. This leads to the maximum solution usage possible with maximum effluent and maximum chemical costs. As a result the whole system is unattractive especially for a minilab environment where minimum effluent is required. It is believed that it is these shortcomings that have inhibited commercial use of this process.
Japanese specification 64/44938 appears to describe such a system in which a silver chloride colour material is processed in a low volume of a single-bath amplifier solution. The processes described therein however fall short of what is required in the fully commercial environment for exactly the reasons given above.
The present invention provides a method and apparatus which can use the minimum processing solution while allowing fully acceptable results and comparatively easy implementation in the minilab environment.
According the the present invention there is provided a method of processing an imagewise exposed photographic material in a processing solution which is unstable to the extent that it deteriorates without external reaction in which said photographic material is passed through a tank containing said solution characterised in that the solution is circulated through the tank at a rate of from 0.1 to 10 tank volumes per minute.
The preferred circulation rate is from 0.5 to 8, especially 1 to 5 and particular from 2 to 4 tank volumes per minute.
In a preferred embodiment of the present method, the processing solution is replenished such that the processing performance of the solution remains within predetermined acceptable limits.
The predetermined acceptable limits are preferably those which are accepted in the trade as desirable as measured in terms of the sensitometric performance of a processed test image.
The time taken for a particular solution to deteriorate can be determined by storing it in a closed container for va
REFERENCES:
patent: 2186927 (1940-01-01), Hughey
patent: 4954425 (1990-09-01), Iwano
patent: 5043756 (1991-08-01), Takabayashi et al.
patent: 5179404 (1993-01-01), Bartell et al.
Patent Abstracts of Japan, vol. 13, No. 242, (P-880) (3590), 7 Jun. 1989, and JP, A, 144938 ()Fuji Photo Film(. Ltd.) 17 February 1989 cited in the application.
Baretll Roger
Dunlop James I.
Earle Anthony
Glover Edward C. T. S.
Marsden Peter D.
Baxter Janet C.
Eastman Kodak Company
Huff Mark F.
Pincelli Frank
LandOfFree
Method and apparatus for photographic processing 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 and apparatus for photographic processing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for photographic processing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1109690