WO1991017482A1

WO1991017482A1 - Photographic processing apparatus

Info

Publication number: WO1991017482A1
Application number: PCT/EP1991/000785
Authority: WO
Inventors: Anthony Earle; Edward Charles Timothy Samuel Glover; Peter Douglas Marsden
Original assignee: Kodak Limited; Eastman Kodak Company
Priority date: 1990-04-27
Filing date: 1991-04-23
Publication date: 1991-11-14
Also published as: GB9009472D0

Abstract

A low volume thin tank photographing apparatus includes a tank (1) having a narrow passage (2) through which imagewise photographic material (5) to be processed is passed. At the inlet (7) of the tank (1) a reservoir (7) for photographic processing solution (8) is provided. Solution is circulated in a circuit (14) between inlets (9, 10), and outlets (11, 12).

Description

PHOTOGRAPHIC PROCESSING APPARATUS

This invention relates to photographic processing apparatus of the kind in which an imagewise exposed photographic material is passed through a processing solution in a low volume tank by conveying the material along a path in the tank from an inlet to an outlet and in which the solution is constantly replenished.

There has recently been developed photographic processing apparatus which is known as low volume thin tank apparatus and is as described for example in our co-pending patent application No. 9003282.2, which is particularly useful for a redox amplification process. In such a process colour materials are developed to produce a silver image and then treated with a redox amplifying solution to form a dyeing solution. The redox amplifying solution contains both an oxidising agent and a colour developing agent, which is a reducing agent. The presence of these two agents means that the whole solution is basically unstable and therefore unless the solution is used within a short time after being freshly mixed it loses its effectiveness and has to be discarded and a fresh solution mixture used.

To overcome these problems the thin volume tank apparatus proved very successful, since if any solution has to be disposed of it is of essentially a low quantity and hence does not cause the disposal process to become expensive, either in the loss of solution or in dealing with the treatment of any polluting action which the solution may have. However, in order to be successful it is necessary that the solution in the low volume thin tank is constantly changed and it is necessary to ensure that -replenishment occurs on a regular basis and at a rate that one part of the solution does not move with one part of the material being treated as it progresses through the tank but that the material is presented with fresh and changing solution during its passage through the tank to ensure it is fully processed when it reaches the outlet. If the level of the solution falls or any air bubble or air lock occurs in the tank then clearly this would have a deleterious effect on the process and the material would not be properly processed on its exit from the tank.

In a low volume thin tank the image bearing layers in the material process begin to swell and take up solution. Due to the small amount of solution in the tank the material is liable to stick to the side of the tank if sufficient solution is not available. This can lead to jamming.

One proposal whcih has been made to replenish solution is disclosed in British Patent 1109144 where photographic material to be processed is guided into a solution in a tank between two spaced plates defining a narrow passage. The plates are connected at their entrance end each to a hollow tube which has a longitudinal slot through which solution under pressure can pass onto material passing between the cylinders. The solution then feeds between the plates into the tank.

In an alternative proposal, solution in a processing tank which has a number of sets of transporting rollers for material being processed is circulated from a separate reservoir by a pump is disclosed in U.S. Patent No. 4688917 and European Patent Publication No. 0218170.

In both of these prior proposals there is a risk that the same part of a solution may travel with the material being processed through the tank.

It is an object of the present invention to ensure that a low volume thin tank photographic processing apparatus is constantly filled with processing solution to avoid any of the above problems.

According to an aspect of the invention, photographic processing apparatus of the kind in which an i agewise exposed photographic material is passed through a processing solution in the low volume tank by conveying the material along the path in the tank from an inlet to an outlet and in which the solution is constantly circulated, includes reservoir means containing processing solution positioned at the said inlet so that the material is arranged to pass through the processing solution prior to entering the tank and so that the tank is always kept full of solution from the reservoir means.

The reservoir may be in the form of a funnel-shaped portion of the low volume tank at the said inlet.

Feed means are preferably provided for directing the material to be processed through the reservoir means and into the said inlet.

Solution inlet and outlet means are preferably provided and connected at intermediate positions along the tank and the solution may be fed by a circulating pump between the inlet and outlet means. Means may also be provided for feeding replenishing solution to the inlet means as required.

In order to assist with the understanding of the invention one example of photographic processing apparatus in accordance therewith will now be described with reference to the attached schematic section, as shown in the accompanying drawing. The drawing shows a thin volume tank 1 having a passage 2 which is defined by walls 3 and 4. As is indicated by the line 5 photographic material being processed passes along the whole length of the tank and is fed therethrough by input rollers 6.

The entrance to the thin tank 1 is constructed as being of a general funnel shape 7 to constitute a reservoir for photographic solution 8.

The tank has two inlets for feeding photographic solution into the body of the tank and these are shown as 9 and 10 respectively, the inlet 9 being positioned near the funnel 7 and the inlet 10 being positioned just past the central point of the tank. The tank also has two outlets 11 and 12 where solution is taken out of the tank. One of these outlets 11 is positioned just before the mid-point of the tank and the second outlet 12 is positioned near the exit point of the tank.

The inlets 9, 10 and the outlets 11, 12 are connected in a fluid circuit 14 which includes a pump 15. The pump 15 is used to circulate solution between the inlets and the outlets and thus ensure that no stagnant area of solution exists in the tank. The circuit 14 also has a branch inlet connected to a source 17 of solution which is fed in intermittently to replenish the solution in the tank.

The tank further is provided with a drain 18 which when processing has finished can be used to pump out via a pump 19 solution from the tank to waste.

In operation the material 5 to be processed is fed through the rollers 6 into the processing solution 8 in the funnel 7 of the tank and then into the body of the tank 1. The image-bearing surface of the material is on the side of the tank nearest the wall 4 and as the surface progresses through the tank it soaks up solution and expands. This can cause the level of solution in the tank to fall but if the amount in the funnel is correctly inserted all that happens is that the level of the solution in the funnel 7 lowers slightly. The whole of the tank will be filled with solution and because of this there will be a liquid surface between the walls 3, 4, of the tank 1 and the material 5 so that no sticking of the material 5 to the walls 3, 4, will occur. During processing, the pump 15 operates to circulate the solution 8 to the inlets 9, 10, and into the tank and through the circuit 14 back to the inlets again. This constant circulation and the movement of the material 5 within the tank ensures that there is no risk of one piece of the material 5 travelling with the same solution and thus not being properly processed.

The material 5 will, of course, take some of the solution with it out of the tank and this means that the tank has to be replenished occasionally. This is done through the inlet into circuit 14 from the replenshing stock of solution held at 17. The replenishment is such that the level in the funnel 7 is always kept up to a reasonable level. If, however, there is any sudden spillage or leakage of solution 8 from the tank, the solution in the reservoir 7 will automatically compensate for this until replenishment can be achieved.

The use of the invention ensures that the processing solution is constantly fed to replenish the tank and that, due to the reservoir effect of the funnel, no interruptions in the solution occur so that the material being processed is correctly and efficiently processed with the minimum wastage of solution.

Claims

1. Photographic processing apparatus of the kind in which an imagewise exposed photographic material is passed through a processing solution in a low volume tank by conveying the material along a path in the tank from an inlet to an outlet and in which the solution is constantly circulated, characterized by including reservoir means (7) containing processing solution (8) positioned at the said inlet so that the material (5) is arranged to pass through the processing solution (8) prior to entering the tank (1), and so that the tank (1) is always kept full of solution from the reservoir means(7) .

2. Photographic processing apparatus as claimed in claim 1 characterized in that in the reservoir means is constituted by a funnel-shaped portion (7) of the tank (1) at said inlet.

3. Photographic processing apparatus as claimed in either preceding claim and characterized by including feed means (6) for directing the material (5) through the reservoir means (7) and into the tank (1).

4. Photographic processing apparatus as claimed in any preceding claim and further characterized by including solution inlet (9,10) and outlet (11,12) means connected at intermediate positions along the tank (1).

5. Photographic processing apparatus as claimed in claim 4 characterized in that the solution (8) is arranged to be circulated by pump means (15) in a circuit (14) between the inlet (9,10) and outlet (11,12) means.

6. Photographic processing apparatus as claimed in claim 5 characterized by including inlet means for feeding replenishing solution to the inlet means (9,10) as required.