Method of processing photographic silver halide materials

Abstract: A method of imagewise exposing and thereafter processing a photographic silver halide colour material in a machine containing a number of non-replenished processing tanks or processing tanks which are supplied from a non-replenished source wherein the exposure time is automatically increased by a predetermined factor related to the area of photographic material already processed and the volume of the non-replenished processing solution.

Description: Field of the Invention The invention relates to a method of processing a photographic silver halide material which enables non-replenished processing baths to provide images of non-varying quality. Background of the Invention In the field of photographic processing it is well known to replenish processing solutions to compensate for loss of developer components by consumption by the process and aerial oxidation. Such a replenishment system requires replenisher pump(s), pipework and control means, all of which adds to the cost of the machine. Some processing machines can be supplied by premixed solutions which are usually run until they produce unacceptable results. At this point the solutions are discarded and are never replenished. This clearly avoids the replenishment system described above. Examples of prior art processing machines are disclosed in US-A-3 462 221, GB-A-1 040 601 and WO 93/11463 Problem to be Solved by the Invention The problem experienced with such non-replenished machines is that the quality of the images produced will deteriorate with continued use of the same solution. This means that the processing solutions must be discarded at a comparatively early stage if unvarying high quality processing is desired. Summary of the Invention According to the present invention there is provided a method of imagewise exposing and thereafter processing a photographic silver halide colour material in a machine containing a number of non-replenished processing tanks or processing tanks which are supplied from a non-replenished source comprising the step of automatically increasing the exposure time of the photographic material by a predetermined factor related to the area of photographic material already processed and the volume of the non-replenished processing solution. Advantageous Effect of the Invention The materials processed employing the present method have substantially unvarying sensitometric quality over a longer time period than when uniform exposure has been given to each image. Brief Description of the Drawings In the accompanying drawings Fig 1 is a schematic diagram of processing apparatus which may be used while Figs 2 and 3 represent the results of the Examples. Detailed Description of the Invention The present method applies to situations where the exposure time is under the control of the processer rather than the original photographer. For example, this would include the making of colour prints or duplicate slides or prints. In a preferred embodiment the non-replenished processing solution is a colour developer solution. A typical printer machine gives red, green and blue exposures automatically adjusted according to its determination of a number of parameters. The control of the exposure required by the present invention may be different for each colour exposure. The present invention is particularly applicable to processing machines which accept a solution supply unit in which there are separate compartments holding the various solutions needed. Preferably one or more of the processing solutions are circulated between the a solution supply unit and the processing tank continuously or intermittently. In one embodiment of the present invention the processing machine is controlled by a microprocessor which receives data from the processing machine as to the area of photographic material processed. In response to this data the exposure time in one or more colour exposures is increased by a predetermined factor. In order to find out what the predetermined factor should be, measurements are taken during a processing run of photographic material exposed to a colour step wedge which has been processed without any exposure adjustment. The speed of each image can then be determined in the usual way. This will then given an indication of the factor by which the exposure should be increased to compensate for apparent loss of "speed" due to solution deterioration. Typically the increase in exposure per print will depend on the size of the print and the volume of processing solution being used. The increase gets bigger with less solution and with larger sheets. In one embodiment the increase in exposure is by a factor in the range 1.0005 to 1.005, preferably in the range 1.002 to 1.004 per A4-sized print in 500ml processing solution. There may be variations in these rates for each colour exposure. The preferred processing solution whose volume is taken into account is the colour developer solution. It is, of course, the developer solution which is particularly critical in colour processing but it is not the only solution to which the present method can be applied. In Fig 1 of the accompanying drawings the processing machine comprises a rapidly rotating processor drum (1) which rotates in a tank of small volume (2) having input transport rollers (3) and output transport rollers (4) through which the sheet of photographic material is driven. The processing machine will also comprise other processing tanks (not shown) as is well understood. The processing solution (6) for tank (2) is held in reservoir (7) and is circulated by pump (8) through pipes (9) and (10). The preferred type of photographic material to be processed by the present method is negative colour paper. A particular application of this technology is in the processing of silver chloride colour paper, for example paper comprising at least 85 mole percent silver chloride. Typically the photographic elements can be single color elements or multicolor elements. Multicolor elements contain dye image-forming units sensitive to each of the three primary regions of the spectrum. Each unit can be comprised of a single emulsion layer or of multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In an alternative format, the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer. A typical multicolor photographic element comprises a support bearing a cyan dye image-forming unit comprised of at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, and a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler. The element can contain additional layers, such as filter layers, interlayers, overcoat layers, subbing layers, and the like. In the following discussion of suitable materials for use in this invention, reference will be made to Research Disclosure, December 1989, Item 308119, published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire P010 7DQ, ENGLAND, which will be identified hereafter by the term "Research Disclosure." The Sections hereafter referred to are Sections of the Research Disclosure. The silver halide emulsions employed in the elements of this invention can be either negative-working or positive-working. Suitable emulsions and their preparation as well as methods of chemical and spectral sensitization are described in Sections I through IV. Color materials and development modifiers are described in Sections V and XXI. Vehicles are described in Section IX, and various additives such as brighteners, antifoggants, stabilizers, light absorbing and scattering materials, hardeners, coating aids, plasticizers, lubricants and matting agents are described , for example, in Sections V, VI, VIII, X, XI, XII, and XVI. Manufacturing methods are described in Sections XIV and XV, other layers and supports in Sections XIII and XVII, processing methods and agents in Sections XIX and XX, and exposure alternatives in Section XVIII. Preferred color developing agents are p-phenylenediamines. Especially preferred are: 4-amino N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N-ethyl-N-(b-(methanesulfonamido) ethyl)aniline sesquisulfate hydrate, 4-amino-3-methyl-N-ethyl-N-(b-hydroxyethyl)aniline sulfate, 4-amino-3-b-(methanesulfonamido)ethyl-N,N-diethylaniline hydrochloride and 4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine di-p-toluene sulfonic acid. Photographic processing methods are described in Section XIX of Research Disclosure. The following Examples are included for a better understanding of the invention. EXAMPLE 1 All processing was carried out in a processing machine, in which the paper experiences high agitation by contacting a rotating drum, similar to one made of several units described in PCT publication no. WO 93/11463. Processing solutions were pumped continuously through the processor tanks by a peristaltic pump pumping 25mls/min. One tank's recirculation system is shown in Figure 1. Kodak 'Supra' colour paper, surface F, sheets of size A4 were used for testing the sensitometry every ten or so processed sheets. This was exposed to a neutral 0.15 log exposure wedge. The process was seasoned by processing a fully exposed A4 sheet of the same paper followed by three unexposed sheets, then another fully exposed sheet followed by three unexposed ones and so on. This approximated 25% maximum exposure which is considered to be about equivalent to average printed density of normal prints. The wedge exposed strips were counted as unexposed strips. The process sequence was: Process Time (seconds) Temp. Total tank + circulation volume Develop 30 40°C 500mls Bleach-fix 30 22°C 500mls Stabilise 15 22°C 500mls Stabilise 15 22°C 500mls Stabilise 15 22°C 500mls The starting developer was one with the following formula (this is similar to RA4 replenisher): Triethanolamine 11.0ml Diethylhydroxylamine 6.0ml CD3 7.3g Phorwite™ REU 3.0g Disodium EDTA 3.0g Catechol disulphonic acid 3.0g Potassium chloride 0.0g Potassium carbonate 25.0g Water to pH adjusted to 10.4 1 litre The starting formula of the bleach-fix was as follows (this is similar to RA4 bleach-fix NR) 1.56M Ammonium iron(III) EDTA 275ml Ammonium thiosulphate 225g Sodium sulphite 42g Water to pH adjusted to 5.5 1 litre The three wash tanks (not shown) in the processor were filled with fresh RA4 stabiliser. After the equivalent of 100 sheets of paper had been processed along with the exposed wedges, the sensitometry of the exposed wedges was determined and the speeds and contrasts calculated. Figures 2 and 3 show the change in speed and contrast of the paper with seasoning respectively. The contrast of all layers stayed more or less constant for the first 60 sheets of paper. This is probably the practical limit of this process/paper combination with no replenishment. The speed of paper decreased more or less linearly with seasoning. The fractional speed change per sheet was 0.0035 for the green and blue sensitive layers and 0.0022 for the red. EXAMPLE 2. Example 1 was repeated except that instead of processing a wedge every 10 or so sheets, a picture was processed. This picture was exposed on a digitally controlled enlarger. The exposure to give a good print was determined for an unseasoned process. During the test run, the exposure of the print was adjusted to allow for the seasoning. Using the data from Example 1, it was calculated that the exposure time had to be increased by a factor of 1.0035 for green and blue exposures, and 1.0022 for the red exposure. The processed pictures were collected together and viewed by eye. The resulting print were virtually indistinguishable from each other.

Claims: A method of imagewise exposing and thereafter processing a photographic silver halide colour material in a machine containing a number of non-replenished processing tanks (2) or processing tanks which are supplied from a non-replenished source (6,7), characterised by the step of automatically increasing the exposure time by a predetermined factor related to the area of photographic material already processed and the volume of the non-replenished processing solution. A method as claimed in claim 1 in which the said non-replenished processing solution is a colour developing solution. A method as claimed in claimed in claim 1 or 2 in which the said factor is in the range 1.0005 to 1.005 per A4-sized print in 500ml colour developer. A method as claimed in claimed in claim 3 in which the said factor is in the range 1.002 to 1.004 per A4-sized print in 500ml colour developer. A method as claimed in any of claims 1-3 in which the photographic material is a negative colour paper whose silver halide emulsions comprise at least 85% silver chloride. A method as claimed in any of claims 1-4 in which the processing solutions are fed from a replaceable solution supply unit in which there are separate compartments holding the various solutions needed. A method as claimed in claim 6 in which one or more of the processing solutions are circulated between the solution supply unit and the processing tank continuously or intermittently.

Inventors: FYSON JOHN RICHARD, FYSON, JOHN RICHARD, FYSON, JOHN RICHARD, C/O KODAK LIMITED
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1995
Main classification: G03D13
IPC codes: G03C5, G03D13, G03C7, G03D3