WO2004086138A1

WO2004086138A1 - Processing method and apparatus

Info

Publication number: WO2004086138A1
Application number: PCT/GB2004/001040
Authority: WO
Inventors: John Richard Fyson; Peter Hewitson
Original assignee: Eastman Kodak Company
Priority date: 2003-03-27
Filing date: 2004-03-11
Publication date: 2004-10-07
Also published as: GB0307048D0

Abstract

A method of processing uses a common delivery means to supply a starter solution and a replenisher solution to the processing apparatus. The volume of the delivery means is equal the volume of starter solution required to convert a fixed volume of replenisher solution such that there is substantially no change in sensitometry of the material as is it processed.

Description

Processing Method and Apparatus Field of the Invention

This invention relates to the field of photographic processing, in particular to the metering of processing solutions.

Background of the Invention

To prevent the working characteristics of a bath of photographic developer from changing during the development of a quantity of exposed silver halide photographic material, and also to maintain the volume of the developer, it is common practice to add a replenisher. Such a replenisher is usually a more concentrated aqueous solution of the principal developer constituents that are consumed during development. The replenisher has a reduced concentration of components released during development so that these compounds are diluted. In this way the developer tank solution can be maintained at a constant composition. If the replenisher were to be used in the processor when the process was first started it would be too active, i.e. it would have a higher concentration of consumed products compared to the equilibrium position and low concentrations of released products. In order to get around this problem a specially formulated 'tank' solution can be used which has the same activity and approximately the same constitution as the equilibrium constitution of the developer tanks. This 'tank' solution can usually be made by diluting the replenisher and adding a starter. In this way the developer replenisher has the same activity and similar constitution as the final equilibrium 'tank' developer.

The starter is often a mixture of acid, usually acetic acid or a bicarbonate, and alkali metal halides. The volume of halides added is determined by experiment or calculation. US 3276874 suggests using hydrobromic acid as a starter solution as this has less components and does not introduce an alkali metal ion. If the process is started automatically with a fresh solution the tank solution has to be made and a starter has to be supplied to the processor. This could be done manually in a processor that is only started from fresh occasionally such as in a minilab. However some low volume and single use processors must be started from fresh frequently. This is done most conveniently and reliably by carrying out this action automatically. In this case, if the processing is done with replenisher, an additional tank of starter has to be supplied. This involves more equipment, required to meter, pump and detect empty tanks etc. Whichever method is used the amount of starter added to a given volume of replenisher is important since it is important to arrive at the right constitution of tank solution for the process to remain constant.

Single use processors need washing between each process to remove the chemistry of the last step of the process. Low volume processors, such as the one described in PCT GB2002/004141, are designed to process a length of material and then be washed out when no further processing is envisaged, for example after a certain delay in between orders. The washing of the processor ensures that no chemistry is left in the processor that might affect the next process cycle. It also removes any potential for the crystallisation of deposits on the processor parts. Usually water is used to carry out this washing or cleaning.

The wash, or cleaning, solution has to be supplied to the processor, either directly from a convenient water supply should it be available or from an additional tank in the processor . The latter takes up valuable space in the processor and requires some associated ancillary equipment such as pumps and level detectors to pump the solution into the machine. The volume of this extra tank can be minimised by using counter current machine washing, as described in EP 03003321.2, but still has to form part of the processing apparatus.

Problem to be solved by the Invention The invention aims to provide a method and apparatus having a reduced number of supply pipes, pumps, ancillary equipment, etc..

Summary of the Invention

According to the present invention there is provided a method of replenished continuous processing in which a starter solution is supplied to the processing apparatus through the same delivery means as a replenisher solution, the volume of the delivery means being equal to the volume of starter solution required to convert a fixed volume of replenisher solution such that there is substantially no change in the sensitometry of material as it is processed.

Preferably the starter solution is the same solution as used for the cleaning solution. The invention further provides a processing apparatus including a supply tank and a pump for each required solution, the apparatus having common delivery means from the tank supplying starter solution and the tank supplying replenisher to a processing tank, the volume of the common delivery means being equal to the volume of starter solution required to convert a fixed volume of the replenisher solution such that there is substantially no change in the sensitometry of material as it is processed.

Advantageous Effect of the Invention

The method of the invention ensures a fixed amount of starter solution is automatically added to the replenisher solution at the start of a fresh tank. This is particularly advantageous for low volume processors which may be used for small batches of processing and consequently are started and stopped more frequently than large processors.

The method reduces the number of supply tanks required for the processing apparatus. The cleaning solution leaves no solid residue in the apparatus.

In a preferred embodiment the same solution is used for both the cleaning solution and the starter solution. The starter solution is used to convert the replenisher solution into a tank solution so that the process can be run such that there is little or no change in the sensitometry of the processed material.

Brief Description of the Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic drawing showing the apparatus according to the invention;

Figure 2 is a graph showing density versus length for a control strip; Figure 3 is a graph showing density versus length for a strip processed in accordance with the invention;

Figure 4 is a second graph showing density versus length for a control strip; and Figure 5 is a second graph showing density versus length for a strip processed in accordance with the invention.

Detailed Description of the Invention

Figure 1 is a schematic drawing showing the apparatus according to an embodiment of the invention. In this figure the starter solution is also used as a cleaning solution. Hence only one storage tank is provided for this solution. It will be understood by those skilled in the art that if the starter solution and the cleaning solution are not the same solution a further storage tank will be required. A processing tank 80 is supplied from a first storage tank 10 and a second storage tank 70. Storage tank 10 contains starter/cleaning solution. Storage tank 70 contains replenisher solution. A pump 30 is provided for pumping starter/cleaning solution from the tank 10 to tank 80 via pipe 20 and delivery pipe 90. A pump 50 is provided for pumping replenisher from tank 70 to tank 80 via pipe 60 and delivery pipe 90. Delivery pipe 90 is thus common to the fluid path of both solutions. The volume of delivery pipe 90 is fixed and is determined by the amount of starter solution required to convert a predetermined amount of replenisher to result in the correct composition of developer in the tank 80. A valve 40 ensures that the solutions supplied by tanks 10 and 70 are directed towards the tank 80. During the cleaning stage of the process pump 30 pumps cleaning solution from the storage tank 10 into the processor tank 80. The solution passes through pipe 20, valve 40 and delivery pipe 90. After cleaning is complete the processor tank 80 is drained. A fixed amount of solution remains in the delivery pipe. This is equal to the volume required to convert the replenisher, as described above. When processing begins a known volume of replenisher is pumped by pump 50 from tank 70. The solution passes through pipe 60, valve 40 and delivery pipe 90. However the delivery pipe is still full of starter/cleaning solution which the replenisher must displace before it can enter the tank 80. Replenisher continues to be pumped until both the starter/cleaning solution and the required volume of replenisher solution has entered tank 80. This volume of replenisher is equal to the volume of replenisher pumped from tank 70 minus the volume of the common delivery pipe 90. This delivery system ensures the correct composition of developer, formed from starter solution and replenisher solution, is in the tank 80 to ensure constant sensitometric characteristics. Any replenisher left in the tank is washed out.

Example 1

The experiment was carried out in a low volume processor as described in PCT GB2002/004141. It was built with a 4 inch (10.2cm) tray width with two consecutive trays - one for developer and one for bleach fix. Washing after the bleach was by means of an inclined plane ramp, as described in GB 0220263.8. Each tray was fitted with a replenishment pump and a drain pump. Each tray could be charged by turning on the replenisher pump only. During the processing operation the level in the tank was kept constant by adjusting the drain pump to keep the amount of liquid in the tray constant. The delivery pipe to the processor, common to both developer replenisher and starter/processor cleaning solution, was cut to a length to give a volume of 8ml. This pipe did not drain onto the processor when the pumps were switched off. The following solutions were used;

Developer Replenisher To make one litre

875g water (demineralised)

33g potassium carbonate

5g DEHA 7.5g CD3 (used part b of a kit as had run out ) lOdrops Tween 80 lml Dequest 2010

2g Blankophor REU pH adjusted with 10% nitric acid to 10.5

Starter/Processor Cleaning solution

0.10 mole/litre hydrochloric acid to which was added 2g/l Tween 80

Bleach-fix To make 1 litre

200 ml 1.56M ferric ammonium EDTA solution

140g ammonium thiosulphate

20g sodium metabisulphite lOg glacial acetic acid pH adjusted to 6.0 with either ammonia solution or sulphuric acid

Paper Wash

Tap water to which was added 2g/l Silwet L-7607.

Long lengths of Ektacolor Edge 8™ glossy surface colour print paper were exposed in a constant exposure sensitometer to give an even constant density of about 0.8 in all layers. This was cut into lengths approximately 105cm long and processed using the baths of formulae outlined above and in the 4 inch (10.2cm) processor as referenced above with settings to give the following process.

Before processing the processor was cleaned with either four 20ml changes of water(the control comparison) in the counter-current mode discussed in EP 03003321.2 or four 20ml changes of starter/processor cleaning solution (in accordance with the invention), also delivered in the same counter-current mode.

The trays were drained of liquid and allowed to dry. No crystals were seen in the trays with either solution. To start the process either 8mls of water (the control comparison) or starter/processor cleaning solution (in accordance with the invention) was pumped into the developer tray, fed from the same storage bottle as the cleaning solution. This was followed by pumping in 22ml developer replenisher. 30ml bleach-fix developer and replenisher were pumped into the bleach-fix tank. The mixture was stirred for about 15s by starting the agitation rollers at a rate of 1Hz. The replenisher pumps were started and a length of paper inserted into the processor. This was carried out for both the control comparison and for the solution in accordance with the invention. The strips were allowed to dry at room temperature and then the densities read with a densitometer at 1 cm intervals. The results of the experiment are shown in Figures 2 and 3.

After processing the processor was washed in the same way as before processing. No crystals were seen with either the water or the starter/processor cleaning solution.

The results show that the change in density was much greater with the comparison process, water being used as the starter and wash solution compared to the invention with the hydrochloric acid wash. No residue was seen in the tank with the invention. This demonstrates that a starter solution containing only volatile materials can also be used to wash the processor and be delivered from the same storage bottle.

Example 2

Example 1 was repeated with an alternative starter/processor cleaning solution and a faster process:

Starter/Processor Cleaning solution

0.00075 mole/litre hydrobromic acid to which was added 2g/l Tween 80

Figure 4 shows the effect of seasoning with no starter/processor cleaning solution added to the replenisher in the tray at the beginning. Figure 5 shows the effect of seasoning with starter/processor cleaning solution added to the replenisher in the tray at the beginning. It will be understood by those skilled in the art that the invention is not limited to the use of cleaning solution as a starter solution. The cleaning solution could also be used as a stop solution for use after a developer and before a bleach/fix or fixer.

The invention has been described in detail with reference to preferred embodiments thereof. It will be understood by those skilled in the art that variations and modifications can be effected within the scope of the invention.

Claims

Clai s:

1. A method of replenished continuous processing in which a starter solution is supplied to the processing apparatus through the same delivery means as a replenisher solution, the volume of the delivery means being equal to the volume of starter solution required to convert a fixed volume of replenisher solution such that there is substantially no change in the sensitometry of material as it is processed.

2. A method as claimed in claim 1 wherein the starter solution is the same solution as used as the cleaning solution.

3. A method as claimed in claim 1 or 2 wherein the replenisher solution is to replenish the developer.

4. A method as claimed in claim 1, 2 or 3 wherein the starter solution is the same solution as the stop solution.

5. A processing apparatus including a supply tank and a pump for each required solution, the apparatus having common delivery means from the tank supplying starter solution and the tank supplying replenisher to a processing tank, the volume of the common delivery means being equal to the volume of starter solution required to convert a fixed volume of the replenisher solution such that there is substantially no change in the sensitometry of material as it is processed.