US3529529A - Method and means for controlling the addition of replenisher to automatic photographic film processors - Google Patents

Description

United States Patent Inventor Ernst E. Schumacher,

3 !13 Postfach, 6 Frankfurt am Main, Germany Appl. No. 686,561 Filed Nov. 29, 1967 Patented Sept. 22, 1970 Priority Dec. 3, 1966 Germany No. [(60,857

METHOD AND MEANS FOR CONTROLLING THE ADDITION OF REPLENISHER TO AUTOMATIC PHOTOGRAPHIC FILM PROCESSORS 4 Claims, 1 Drawing Fig.

US. Cl 95/89, 23/230, 23/253 Int. Cl 003d 3/06, GOln 31/00 Field of Search I89,

95 96/(Inquired); 23/230, 230A, 253, 253A; 93/3, 93

[56] References Cited UNITED STATES PATENTS 2,770,531 11/1956 Haweset al 23/230 2,977,199 3/1961 Quittner 23/230 2,989,377 6/1961 Leisey 23/230 3,290,116 12/1966 Carroll 23/253(A)UX 3,308,041 3/1967 Strickler 23/23OX Primary Examiner-John M. Horan Assistant Examiner-Robert P. Greiner Attorney-Rummler and Snow sample and then ad usting the rate of supply of the replenishing material in direct relation with the variation of the quantity of the compound in the analyzed samples relative to a predetermined norm.

Patented Sept. 22, 1970 3,529,529

//VVEN7'0R. V m/vsr 5 SCHUMACHER METHOD AND MEANS FOR CONTROLLING THE ADDITION OF REPLENISHER T AUTOMATIC PHOTOGRAPHIC FILM PROCESSORS BACKGROUND OF THE INVENTION In particular the invention concerns the automatic addition of replenisher for the developer being used in automatic photographic film processors.

Film processors serve to develop the latent image in exposed photosensitive emulsions. In the course of this process silver halide is reduced to metallic silver, whereby a reducing agent contained in the developer is used up and a concentration of free halide in the developer takes place. For the continuous development of a series of films of varying sizes and densities it is necessary to add to the developer a quantity of replenisher which corresponds to the actual consumption of developer and to drain away the spent solution. Such replenishers are distinguished from the basic developer bath by having a higher percentage of reducing agent and a smaller percentage of bromides or the complete absence thereof.

The consumption or developer depends mainly upon three factors, i.e., (l) the dimensions of the emulsion coated surface; (2) the average integrated density of the developed image; and (3) the oxydizing components, such as oxygen existing in the air present in the developing section of the processing apparatus.

It is evident, that the influence stated under factor 3 may be reduced to a negligible minimum by the use of a non-oxygen sensitive developer or by using a hermetically sealed developer tank such as that disclosed in my copending application, Ser. No. 671,083, filed Sept. 27, 1967 now US. Pat. No. 3,495,520. The difference between factors 1 and 2, however, consists in that the film surface can be assessed prior to starting the developing procedure whereas the density of the silver image and the corresponding consumption of developer can only be determined upon completion of development.

While the majority of processors is fitted with devices for measuring only the film feeding length it is also possible to determine automatically the width of the film and hence the area of film introduced to the developing section. Suitable elements for this purpose may be constituted by micro-switches or photocells using infra-red and by such means a basic feed rate for the developer replenisher can be established.

The object of the present invention, however, is to add automatically to the developer in film processors a quantity of replenisher solution which is directly proportioned to the actual consumption of developer so that consistent results are obtained over a practically unlimited period of time, whether the machine is in continuous use or not.

SUMMARY OF THE INVENTION This problem is solved by a process whose main feature is the supplementing of the usual supply of replenisher, which is proportional to the film surface, by an automatic control means which adjusts the replenisher supply rate according to the actual consumption of developer, this control being based upon changes of the halide content of the developer bath which are periodically determined by automatic chemical analysis.

Consequently, the basic idea of the invention is to supplement the predosage of replenisher, which is based on the surface of the film fed into the machine, by a corrective value which depends'on the actual consumption of developer and which is periodically determined by chemical analysis of the halide content of the developer bath by titration. I

As mentioned before, the object of the chemical analysis is to determine the halide content of the developer bath, and an essential factor for choosing the appropriate method of assessing the halide content is the fact that the quantity of halide introduced into the developer in the course of development is strictly proportional to the quantity of silver formed by reduction in the photographic emulsion. Besides the advantages of strict proportionality another advantage resides in the fact that means exist for a very sensitive quantitative analysis of halides through potentiometric titration (determination of the end-point).

For an integration of these elements it is suggested that the time of run and/or the output of the replenisher pump be adjustable. For instance, it is possible to provide for a device permitting a fully automatic control of the time of run of the replenisher pump proportional to the film surface and an equally automatic increase or decrease of the rate of replenishment porportional to the lower or higher halide content of the developer bath as compared with a normal value.

It is relatively simple to realize by means of at least three regulators of the replenisher flux, preset at three different quantities. By means of several magnetic valves or a three-way valve, the flux of replenisher is directed via one of these regulators in such a way that for a normal halide content for a given film area the normal quantity of replenisher is added, and for an increase of halide content in the developer bath an increased quantity of replenisher is added and for a decreased halide content the supply of replenisher is reduced.

The same function can also be achieved by means of a remotely controlled regulator, the regulator of the pump speed or an additional control of the time the pump is in operation. It is furthermore possible to apply various systems for automatically determining the dimensions of the film surface.

DESCRIPTION OF THE DRAWING The drawing shows, diagrammatically, a view illustrating a typical film-processing the apparatus, the automatic titration means associated therewith, and the various operational steps of the process which is the subject of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawing a typical film processor 1 comprises an enclosure (shown without the top cover and film transport system) having a feed table 2 for the films to be processed, a control means 3, which may be working either on the photo-electrical or on the supersonic principle, for measuring the feeding rate of the film into the processor, i.e., the time it takes to feed the film into the machine. The film then passes through the various processing tanks which include a tank 4 containing a wetting bath, atank 5 containing the developer, a tank 6 containing the fixer and a tank 7 in which the film is rinsed. It is understood that these tanks are con rectly filled with the corresponding fluids before the processing operation starts.

The impulse registered by control means 3 is fed via electric lead 3a into a programming device 8 which starts the following series of operations. The stock solutions for replenishing, contained in special vessel 9 for the developer and in the vessel 10 for the fixer, are added, for instance, by means of magnetic valves 11 and 12, or appropriate pumps to the respective tanks 5 and 6. These valves 11 and 12 are connected with the programming device 8 by means of electrical lead 8a. The time it takes to add these fluids to the respective tanks is controlled by the programming device 8 to be proportional to the time it takes to feed the film into the processing machine or to the film surface area. The conduit of the developer replenisher which is situated beneath magnetic valve 11', is so designed that the replenisher passes through one of the three normally closed magnetic valves l3, 14 or 15. The three valves have different size orifice or passage cross-sections and, as will be explained, only one at a time of the three valves is used to add the replenisher to the developer tank 5. The orifice cross-section of valve 14, in the center, is sized to provide the normal or basic rate of flow of replenisher, the cross-section of valve 13 is smaller, thus reducing the rate of flow of replenisher and the cross-section of valve 15 is larger so that a greater quantity of replenisher may be added to the developer tank 5. When starting the operation the apparatus is set for the normal replenishing rate, the replenishing flow being by way of magnetic valve 14.

Simultaneously with the feeding of the first film into theautomatic processor the programming device 8 starts by way of electrical lead 8b, the operational cycle of the titration apparatus 19.

The operation of the titration apparatus 19 begins with the precision pump 20 which may, for instance, be constituted by a power-driven burette. This pump 20 draws a preselected quantity of the developer solution or composition from the developer tank by way of the conduit 21. Thereby the suction cylinder 22 is filled with the solution to be analyzed, and to effect this the normally closed magnetic valve 23 in the conduit 21 is opened simultaneously with the operation of the pump and the small normally closed magnetic valve 24 in the drain conduit 24a remains closed. The piston moving in the suction cylinder of the power-driven burette remains for a few seconds in its lowest position, then magnetic valve 23 is closed, the valve 24 is opened, and the piston returns to its uppermost position whereby the preselected quantity of developer composition is transferred into the test receptacle 2S. Simultaneously a smaller power-driven burette 26 draws the titration solution (silver nitrate) in an accurately predetermined concentration from the stock vessel 27, via conduit 28 and transfers it via conduit 29 to thetest receptacle 25. The flow of the titration solution from vessel 27 to the test receptacle 25, by way of pump 26, is controlled by magnetic valves 30 and 31 in the same manner as the flow of the developer composition by way of the pump 20.

A power-driven (motor 32) stirrer associated with the test l m; H. .7 v l. The method for automatically replenishing a chemical composition constituent which is consumed at a variable rate during a process in which said composition is used, the said composition being a developer bath for photographic film and .the said constituent being the reducing agent for the silver halide in the film emulsion, which comprises continuously supplying to the processing composition a replenishing quantity 20 of the said constituent substantially equal to the average rate receptacle 25 produces a homogeneous mixture of the two solutions. The measuring electrode 33 extending into the test receptacle 25 and linked to an amplifier 34 by means of line 35, furnishes the potentiometric value which is transferred by the amplifier 34 to the measuring instrument 36 which comprises a contacting element 37 and the contact ranges 38, 39 and 40. The contact range in which the measured value appears determines which one of the magnetic valves l3, 14 or 15 is opened while the two others are closed.

Upon completion of the measuring procedure the magnetic valve 41 below the test receptacle 25 is opened and the potentiometrically measured solution is drawn off to waste through,

drawing of developer composition from the tank 5 through the conduit 21 is interrupted by closure of the valve 23. A new analyzing cycle starts again when the next film is fed to the processor, whereby the control element 3 and the programming device 8 operate in the above described way. The selected magnetic valve 13, 14 or 15 operated after each analof consumption thereof as the composition is being used, periodically extracting a sample of the said composition dur- ,ing the said process and analyzing said sample to determine the free halide content thereof, and then adjusting the rate of supply of the said constituent in direct relation with the variation of the quantity of free halide in successive samples to maintain the desired concentration thereof in the processing *com osition.

2. lhe method as defined by claim 1 wherein the free halide content of the sample is determined by titration content of the sample is measured potentiometrically and the rate of supply of reducing agent to the developer bath is adjusted according to the potentiometric value of the said sample.

4. Means for maintaining a predetermined normal concentration of reducing agent in the developer bath of apparatus for processing photographic film comprising means for supplying a reducing agent replenisher to said bath at an average .4 rate commensurate with the surface area of film being conduit 42. As long as the analysis is in progress any further ysis by the contact'piece 37, remainsopen until-following aprocessed, means for periodically extracting measured amounts of the developer bath, titration means for testing each of said measured amounts potentiometrically to measure the free halide content thereof, and"'means actuated by the potentiometric impulse produced from said titration means for adjusting the rate of supply of the replenisher in direct relation with the rate that the said reducing agent is consumed in the processing apparatus.

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