US3368472A

US3368472A - Device for maintaining a photographic processing solution at a predetermined composition

Info

Publication number: US3368472A
Authority: US
Inventors: Leo Paul Van Bouwel; Tack Willy Pieter
Original assignee: Gevaert Photo Producten NV
Current assignee: Gevaert Photo Producten NV
Priority date: 1963-12-20
Filing date: 1964-12-21
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13
Also published as: GB1045450A; BE657290A; NL302435A

Description

Feb. 13, 1968 L. P. VAN BOUWEL ET AL 3,368,472

DEVICE FOR MAINTAINING A PHOTOTOGRAPHIC PROCESSING SOLUTION AT A PREDETERMINED COMPOSITION Filed Dec. 21, 1964 I r I 1 I I I I awdz, mwww ATTORNEYS INVENTORS' 3,368,472 DEVICE FOR MAINTAINING A PHOTOGRAPH- IC PROCESSING SOLUTION AT A PREDETER MINED COMPOSETION Leo Paul Van Bouwel, Mortsel-Antwerp, and Willy Pieter Tack, Berchem-Antwerp, Belgium, assignors to Gevaert Photo-Producten N.V., Mortsel, Belgium, a Belgian company Filed Dec. 21, 1964, Ser. No. 419,727 Claims priority, application Netherlands, Dec. 20, 1963,

302,435 Claims. (Cl. 95-89) ABSTRACT 0F Til-IE DISCLOSURE When a sufficient amount of photographic material has been processed to require replenishment of the processing solution, a measuring device actuates a flow of fresh solution to a measuring tank. When the desired level of solution is reached in the tank, a float stops the flow of solution therein and a self-starting siphon discharges the contents of the tank until the siphon is broken by the lower level of solution. The effective volume of the tank and the intake end of the siphon can be adjusted.

The invention relates to a device for maintaining a photographic processing solution at a predetermined composrtion.

ln the processing of light-sensitive and photographic material it is desirable for the developing solution to be of substantially constant composition otherwise the time and temperature for obtaining a standard degree of development will vary. Thus in developing large quantities of light-sensitive material on a continuous process basis, it is necessary to replenish the developer solution at substantially the same rate as is being consumed.

The volume of a replenishing liquid can be determined either by calculation or by experiment to restore a photographic processing solution to its former composition after processing a known amount of light-sensitive material under known conditions.

It is known to practice devices for maintaining a photographic processing solution at a predetermined composition wherein at a certain moment a constant amount of replenishing liquid or solution is added to a photographic processing bath. Such devices usually comprise a small measuring container which is provided with a feed valve and a discharge valve and which is. arranged to contain a constant amount of solution.

Each time the discharge valve is opened, a constant amount of processing solution is flowed from the container to the photographic processing bath situated therebeneath. After the container has been emptied, the discharge valve is closed, the feed valve is opened and by gravity or by means of a pump the container is refilled with replenishing solution from the storage tank.

Practice has proved that an accurate volumetric dosing cannot be obtained by means of a device of the kind mentioned above.

Due to crystallization of the replenishing solution at the valves of the container these valves can no longer fully be closed. In case the valves are formed by flexible tubes which are pinched, the rapid ageing of the flexible material of the tubes causes troubles.

The object of the present invention is to provide a device for maintaining a photographic processing solution at a predetermined composition, which does not show the mentioned disadvantages and which permits to add a constant amount of replenishing solution to a photographic processing bath.

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a device for maintaining a photographic solution at a predetermined composition, wherein the amount of re- Another object of the present invention is to provide I plenishing solution which has to be added is adjustable in a very accurate way.

A further object of the invention is to provide a device which is very simple of construction and which requires but little periodical maintenance.

The device for maintaining a photographic solution at a predetermined composition according to the present invention, comprises a measuring container for holding a given quantity of replenishing solution, means for feeding replenishing solution from a storage tank to said container, a siphon in said container with the shorter leg extending in the lower portion of the container, thereby determining the lower level of the replenishing solution in the container, the longer leg of the siphon extending under the bottom of said container and conducting to the lower located photographic processing solution, and the intermediate elevation between both legs being located at the high level the replenishing solution attains in said container, the attainment of the said high level of the replenishing solution in the container being measured by a float which controls the means for feeding the replenishing solution from the storage tank to the container so as to arrest the feed of the replenishing solution once the level of the solution has attained the said intermediate elevation of the siphon, and means for measuring the amount of photographic material which has been treated in the photographic processing solution and for controlling the starting of the means for feeding the replenishing solution to the container after a given amount of photographic material has been processed.

The term amount of photographic material as used hereinbefore denotes theoretically a determined area of such material but, since in practice. the length of the processed photographic material is often measured instead of the area thereof, we wish to extend the scope of the said term in the present invention also to the latter significance.

The feeding of the replenishing solution from the storage tank to the measuring container may occur either by gravity or by a pump. Alternatively, an over-pressure may be maintained in the storage tank, e.g. by means of a nitrogen atmosphere.

According to a particular embodiment of the present invention the siphon is in the form of a U bent tube with legs of uneven length. Said siphon is positioned vertically in the container so that the opening of the short leg is situated near the bottom of the container and the long leg passes through the bottom to extend outwardly.

With reference to the accompanying drawing the invention is illustrated by the following embodiment.

FIG. 1 represents a diagrammatic view of the measuring containers and the storage tanks of a device according to the present invention.

FIG. 2 represents the electric circuit controlling the device of FIG. 1.

FIGURE 3 is a fragmentary view of the short end of siphon of the arrangement in FIGURE 1, showing an adjustable collar to permit adjustment in the lower level of solution in the measuring container.

FIGS. 1 and 2 show a device for maintaining a photographic processing solution at a predetermined composition.

This device comprises the housing 11 which is divided into two measuring containers 13 and -14 by the partition 12. The container 13 is filled with the replenishing solution for the developing bath and the container 14 is filled with the replenishing solution for the fixing bath of a photographic processing apparatus.

Each of the containers is provided with a float 15 Which is vertically movable in a guider 16, a plunger 17 consisting of a cube with inward screw thread, this cube being fitted to a rotatably journalled screw bolt 18, and a siphon 19 having a short leg 20 and a longer leg 21. A hose is connected to the leg 21, conducting to the lower located developing bath resp. fixing bath of the processing apparatus.

The high level of the solution in the containers is indicated by the broken line 22, the low level is indicated by the broken line 23.

In its highest position the float in the container 13 artuates the microswitch S the float in the container 14 actuates the microswitch S The housing 11 and the partition 12, together with the floats 15, the guiders 16, the plunger 17 and the siphons 19, are made out of hard polyvinyl chloride. One of the side walls of the housing 11 is made out of synthetic glass so that the level of the solution in the containers can be easily watched.

The pump 24 pumps the replenishing solution for the developing bath from a storage tank 25 to the container 13 by means of the feed line 26. Similarly replenishing solution for the fixing bath is pumped by the pump 27 from the storage tank 28 to the container 14.

The operation of the replenishing system for one container (13) is now described in a summarizing way. Thereafter a detailed description of the complete device and of the electric control system is given.

At the moment of replenishing the pump 24 driven by the electric motor M is actuated. Solution is pumped from the tank 25 to the container '13 until the solution in the container has reached the level indicated by the broken line 22. At that moment the float actuates the microswitch S so that the motor M is switched ofi and the filling of the container ceases. At the same moment the level of the solution has also reached the intermediate elevation of the siphon, so that the solution starts to flow through the siphon until reaching the low level indicated by the broken line 23. At this moment the contact between the level of the solution and the opening of the short leg of the siphon is interrupted so that the solution ceases flowing away.

It is clear that the level of the solution rises and lowers at each replenishing cycle over a constant distance, i.e. the difference in height between the levels indicated by the

broken lines

22 and 23. Thereby the volume of replenishing solution, which is added during each cycle to the photographic bath, is accurately constant.

The volume of replenishing solution can be reduced by providing an element such as the plunger 17 in the container. Moreover by making this plunger adjustable in the height, the volume of solution added to the bath at each cycle can be accurately controlled. In the present embodiment the plunger 17 can be adjusted by means of the screw bolt 18. The plunger 17 which has a square diameter will slide with one of its flat sides along the side wall of the container 13 upon turning the screw bolt 18. Consequently the plunger will not turn together with the screw bolt and a turning movement of the latter makes the plunger rise or lower.

The operation of the complete device and of the electric control system is as follows.

The contact s of a microswitch, which is provided at the entrance, of the processing apparatus and which is closed by a film sheet moving along, closes the circuit of the motor M This motor is provided with a reduction gear and drives the cam disk 30. When the film sheet has passed the microswitch in the proceessing apparatus, the contact s is re-opened and the motor M is stopped. This opeeration is repeated for each film sheet. It is clear that the cam disk acts here as an integrator since its angular displacement is proportional to the total length of the processed film sheets.

When the cam disk 30 has performed one complete revolution its cam closes the contacts .9 and s The contact s closes the circuits of the relays L and L through the diodes D and D The closed contact s provides for the continuance of the rotation of the cam disk until the cam has passed beyond the contacts s and s Thereby both contacts are opened and the motor M stops.

By means of the contact s it is prevented that the cam disk 30 remains in the position in which the contact .9 has been closed. In such a case the relays L and L would no longer be capable to drop and, even without a film sheet causing the contact s to close, the replenishing would repeat continuously.

The relays L and L remain energized over their respective hold-contacts 1 and 1 Their contacts 1 and 1 close the circuits of the pump motors M and M and the

containers

13 and 14 become filled with replenishing solution. At the moment that the surface of the solution has reached the high level indicated by the broken line 22, the contacts s and s of the respective microswitches S and S are opened by the floats 15.

It has to be noticed that although the filling of both containers is started at the same moment, the filling operation of one container can be ceased prior to ceasing the filling of the other container. Thereby it becomes possible to make both containers feed solution volumes which are different from each other. Moreover, then the dosing device is completely independent from differences in the output of both pumps, from occasional foam-forming in the pipe lines from the pumps to the containers, etc.

When opening the contacts s s the relays L L are dropped. In case that one of the contacts opens before the other, the diodes D and D provide for the dropping of both relays independently from each other.

The electric diagram of the device according to the present invention also shows a contact s This contact, Which belongs to a second microswitch situated near the first mentioned microswitch but laterally spaced therefrom at the entrance of the photographic processing apparatus, has the following function.

As already mentioned hereinbefore the quantity of solution to be replenished is theoretically direct proportional to the surface of the processed film sheets. The microswitch With the contact s only measures the length of the processed film sheets and thus the integration which is made by the cam disk 30 is only correct for one defined film size. Since in practice film sheets of different sizes are processed arbitrarily among each other, an exact dosing of the replenishing solution is impossible. By taking an average value for the difierent sizes of film sheets, the theoretical dosing can be approximately very well in practice.

This close approximation is still enhanced by dividing the different sizes of film sheets into two groups, viz. a group comprising smaller sizes and a group comprising greater sizes of film sheets.

All the film sheets of both groups will close the contact s Only the film sheets belonging to the group of the greater sizes will close also the contact s The resistor R is short-circuited by s so that the motor M will rotate at a higher speed and correspondingly the replenishing action will take place sooner.

By providing some more laterally spaced microswitches at the entrance of the photographic processing apparatus having each their influence on the speed of the motor M the accuracy of the dosing device is still further increased.

The resistors R and R can also be arranged in an adjustable way. Thereby corresponding resistance values may be set for a determined bath composition, bath temperature, processing speed, etc. said values assuring optimal results of the replenishing.

It is clear that the electric system controlling the replenishing system must always meet the requirement that its period will be greater than the time for filling and emptying of the containers.

Indeed, if the cam disk 30 would be capable of performing one revolution during a time which is smaller than the time for filling and emptying a container, then the filling of the container during a following cycle could be started before the level of the solution in the container would be lowered again until reaching the level 23. An accurate dosing would then be excluded.

In the given example of embodiment the adjustment of the volume of the replenishing solution is done by means of the plungers 17. It is clear that also other means can be applied for determining said solution volume. For example as shown in FIGURE 3, the short leg 20' of the siphon can be provided with a collar 20a arranged in a telescoping relationship with its lower end and having a sliding friction fit therewith. Thus, the position of the eifective in take opening of the short siphon leg can be adjusted with respect to the container bottom. For example; by sliding the collar more downwardly the lower solution level indicated by the broken line 23 will decrease so that the replenishing volume increases.

It is not necessary to arrange the siphon in the container but it may also be positioned near the container, the extremity of the short leg communicating with the container.

The device according to the present invention can also be used in the photographic industry for replenishing stop baths, bleaching (fixing) baths, tanning bath, etc.

We claim:

1. Device for maintaining a photographic processing solution at a predetermined composition, comprising a measuring container for holding a given quantity of replenishing solution, means operable to feed replenishing solution from a supply tank to said container, means for measuring the quantity of material being processed, means responsive to said measuring means when a predetermined quantity of material has been processed for operating said solution feeding means, means for halting said feeding means, when the solution level in said container attain a predetermined maximum, anda siphon having a short leg extending within said container with its lower end opening spaced from the container bottom to thereby determine a minimum level of solution in said container, a long leg for discharging the solution outside and below the container into the processing solution, and a bight connecting the upper ends of said legs, said bight being disposed at said maximum level, whereby said solution discharges through said siphon after reaching said maximum level and continues to discharge until said lower level is reached.

2. Device according to claim 1, wherein means is provided for varying the effective volumes of said container below the high level.

3. Device according to claim 2, wherein said means comprises a displaceable plunger.

4. Device according to claim 3, wherein the said plunger is arranged for vertical displacement by means of a vertical rota-tably journalled threaded rod.

5. Device according to claim 1, wherein the extremity of the shorter leg of the siphon is provided with a vertically adjustable collar.

References Cited UNITED STATES PATENTS 440,325 11/ 1890 Richards 9589 2,229,122 1/ 1941 Pershing 137-132 2,778,734 1/ 1957 Fairbank. 2,837,988 6/1958 Pavelle 9589 3,062,123 11/1962 Limberger 95-89 NORTON ANSHER, Primary Examiner.

FRED BRAUN, Assistant Examiner.