FR2695218A1 - Automatic photographic negative film washing system - has microprocessor central control unit which determines the amount of de-ionised water to be added to the washing bath - Google Patents

Abstract

The film washing baths (3,4,5) are cascade mounted. The first bath (3) is permanently fed with a washing liquid consisting of water and a stabiliser. The last bath (5) is fitted with an overflow pipe (9), designed to permit evacuation of excess impurity loaded liquid. The liquid evacuated through the overflow pipe (9) is de-ionised through a resin ion exchanger (16) and the de-ionised water is stored in a bath (18). The water is recirculated and filtered through the bath (13) by injecting de ionised water from the bath) and by adding a determined proportion of stabiliser (24) stored in a concentrated form in the bath (3). The recirculation of water through the bath (3) is managed automatically by a central microprocessor unit (28) which determines the quantity of de-ionised water to inject into the bath (3), as well as the stabiliser proportion. ADVANTAGE - Automatically withdraws washing effluent and reinjects it into first washing bath.

Description

PROCESS AND DEVICE FOR TREATING WASH BATHS
OF AN AUTOMATED FILM DEVELOPMENT FACILITY
NEGATIVES AND PHOTOGRAPHIC TESTS ON PAPER.

 The invention relates to a new method for treating and supplying the washing baths of an automatic installation for the development of negative films and photographic prints on paper. It also relates to the device allowing the implementation of this process.

 In known manner, the facilities for developing negative films, or for printing photographic prints on paper include chemical treatment baths, intended respectively to reveal, whiten, fix, stabilize, etc., ie the negative film proper , or the prints made on paper from such films. The films and the prints on paper from the last chemical treatment bath are then automatically conveyed by means of a rack, in washing baths, intended in addition to removing the chemicals from the previous baths with which they are still partially impregnated, also to stabilize the developed film and the paper print respectively.

 Typically, these washing baths consist of a very high percentage of water, added with a stabilizer in small proportion, typically consisting of surfactants and alcohol or organic derivatives.

 In order to obtain washing and stabilizing baths of constant quality and relative purity, said washing baths are mounted in cascade, the upstream bath being fed continuously and pouring into the consecutive bath or baths up to the downstream bath, the latter being provided with an overflow device allowing the evacuation of the excess washing liquid, the latter being the most charged with impurities, since the bath from which it comes is located immediately following the chemical treatment baths, and in particular that of fixer, in the case of the development of a film only, or of bleaching-fixing in the case of the development of a paper print or that of a film and a paper print simultaneously. In fact, the negative films respectively the paper prints circulate in the direction of increasing purity at these washing baths. The washing baths are also subjected to permanent agitation.

 It is thus understood that in such installations, the quantity of rejection is relatively large. This washing phase alone represents between 40 and 50% of the total volume of rejection. In addition, it is overwhelmingly made up of water. One of the major concerns of the designers of such installations, particularly in the current context of environmental preservation, now lies in the reduction of these discharges or in their reprocessing. Given the large proportion of water from the washing wastes, it is desired to recover it, and possibly inject it in a closed circuit upstream of the washing baths. fi should therefore be treated with effluents from washing in order to recover this water, and reinject it, added with the stabilizer in a proportion determined upstream of the washing bath.

 The subject of the invention is such a method allowing the automatic reprocessing of the effluents from the washing, and the reinjection upstream of the said washing baths of the washing liquid further containing the stabilizer.

This process for the automatic continuous treatment of the washing baths of an installation for the printing and development of photographic films in which said baths are mounted in cascade, the upstream bath relative to the direction of the cascade being continuously supplied by the washing liquid consisting of water and stabilizer, the downstream bath being provided with an overflow device, allowing the evacuation of the washing liquid loaded in excess, is characterized in that it consists:
- Deionizing the liquid from the overflow of the downstream bath on an ion exchange resin, and storing the water thus obtained;
- And to correlatively induce the recirculation and filtration of the upstream bath by injecting the deionized water thus stored, and added in a determined proportion of stabilizer stored in concentrated form, in said upstream bath.

 In other words, the invention consists, on the one hand, in subjecting the washing effluents loaded with impurities to deionization on an ion exchange resin, which is certainly well known for the reprocessing of water, but which further consists in integrating this water reprocessing in an automatic circuit for recirculating the upstream bath, so as to maintain a constant quality of the washing baths, improving the quality of the films developed and of the photographic prints on paper.

 Advantageously, the recirculation is managed automatically by a central unit, fixing the quantities of deionized water to be injected into the upstream bath, as well as the proportion of stabilizer.

 The invention also relates to a device capable of implementing this method. This device comprises a weir directly connected to the overflow device with which the downstream bath is provided, the effluents contained in the weir being pumped periodically when it is full, and sent to an ion exchange resin, including deionized water. obtained is stored in a storage tank, said device further comprising a recirculation circuit ensuring the supply of the upstream bath, said recirculation circuit also receiving in a determined quantity of water from the storage tank and the stabilizer even stored in concentrated form, the injection of deionized water and stabilizer being predetermined.

 The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the example of embodiment which follows, given by way of nonlimiting indication in support of the single appended figure, embodying a schematic representation of the device according to the invention.

 In an installation for developing negative films and / or for printing photographic prints on paper, the treatment baths consist of two main series, namely respectively (1) integrating the chemical treatment baths, typically constituted by the developer. (8), the bleaching-fixing (7), and the fixer (6), within the framework of the treatment of a negative film, and that (2) comprising the washing baths (2), generally three in number or four (3, 4, 5). In the context of the processing of a paper print, there are two chemical treatment baths, namely the developer and the bleaching-fixing.

 These washing baths are permanently supplied with a washing liquid, typically consisting of water, in particular at least up to 95%, and a stabilizer consisting of a surfactant and an alcohol or organic derivatives. .

 In order to maintain a constant quality of these washing baths, they are mounted in cascade, only the upstream bath being in fact supplied with washing liquid. In fact, the excess liquid containing the upstream bath (3) pours into the next bath (4), itself pouring into the downstream bath (5), the latter being provided with an overflow member (9), at which the excess washing liquid can drain off and be temporarily stored in a weir (10). The downstream bath (5) is located immediately following the fixing bath (6) or the fixing bleaching bath in the case of processing a paper print.

 The films, respectively the photographic prints on paper, coming from the fixer (6) or from the whitening fixing, are automatically conveyed by means of a rack in the downstream bath (5), then the intermediate bath (4) and finally in the upstream bath (3), in order to move in the direction of an increasing progression of purity. In fact, the downstream bath (5) is particularly charged with impurities and other dusts discharged respectively by the negative film and / or the photographic print at the level of the downstream bath (5).

 In known manner, these baths are subjected to permanent stirring and filtration by means of a recirculation pump and by passage through a filter.

 According to the invention, the washing effluents from downstream bath (5) are conveyed in the weir (10) at the level of which they are temporarily stored. This overflow is provided with a level detector (11), comprising a low level (12) and a high level (13). In this way, as long as the level of the effluents contained in the weir (10) has not reached the level (13), the liquid contained in it does not undergo treatment. As soon as it reaches the high level (13), the level detector (11) induces pumping (15) of the liquid contained in the weir (10), liquid which advantageously passes through a filter (14) in order to filter the impurities larger.

The effluents are then sent to an ion exchange resin (16), well known for this application.

 After deionization, the quality of the treated water can be continuously monitored, using a conductivity meter calibrated for this purpose or a mineralization tester. In addition, when the resin is saturated, it changes color, indicating the need for its replacement. The water thus obtained is stored in a tank (18).

 According to the invention, the washing liquid contained in the upstream bath (3) undergoes recirculation, ensuring in particular its stirring. This recirculation circuit comprises a point (20) for tapping liquid and an injection point (23). It also includes a pump (22), ensuring the actual recirculation, the liquid withdrawn at the point of connection (20) being advantageously filtered by a filter (21).

 According to the invention, the recirculation circuit also has two inlets (26) and (27), at the level of which are respectively injected the deionized water stored in the tank (18), and pumped by a pump (19), and the stabilizer stored in concentrated form in the reservoir (24), and pumped by a pump (25). In this way, in addition to the recirculation, the circuit (20, 21, 23) also ensures the supply of the upstream washing bath (3), and taking into account the cascade mounting of the various washing baths (3,4,5) , also ensures the regeneration of the washing liquid of these baths.

 This principle of direct injection thus makes it possible to automatically treat the washing baths, ensuring a permanent and continuous injection of a washing liquid of quality and of determined proportion. Indeed, the two pumps (19) and (25) are managed by a central unit (28), typically constituted by a microcomputer.

 The method and the device of the invention thus make it possible to reduce the effluents by a proportion close to 40 to 45%, and in addition, makes it possible to considerably reduce the water consumption, taking into account that it operates almost in a closed circuit. In addition, the resin, typically in the form of a cartridge, can be regenerated.

 Such an installation is very easy to use even by unqualified personnel, the cartridge can be checked visually, in particular by changing the color of the resin when it is saturated.

 In addition, its size is reduced, and it requires little development of existing facilities.

 It therefore proves to be particularly applicable to installations for both development and printing of photographic prints or combined installations integrating these two functions.

Claims (6)

 1 / Process for the automatic continuous treatment of washing baths of an installation for the printing and development of photographic films in which said baths (3,4,5) are cascaded, the upstream bath (3) relative in the sense of the cascade being permanently supplied with the washing liquid consisting of water and stabilizer, the downstream bath (5) being provided with an overflow device (9), intended to allow the evacuation of the liquid of excess washing loaded with impurity, characterized in that it consists of:  - Deionizing the liquid from the overflow (9) of the downstream bath (5) on an ion exchange resin (16), and storing the water (18) thus obtained;  - And to correlatively induce the recirculation and filtration of the upstream bath (3) by injecting the deionized water thus stored (18), and added in a determined proportion of stabilizer 24) stored in concentrated form in said upstream bath (3).  2 / A method according to claim 1, characterized in that the recirculation carried out at the upstream bath (3) is managed automatically by a central unit (28), fixing the quantities of deionized water to be injected into the upstream bath, thus than the proportion of stabilizer.  3 / Method according to one of claims 1 and 2, characterized in that the injection of the stored deionized water (18) and of the stabilizer (24) takes place directly at the level of the recirculation circuit (20,21, 22.23).  4 / Device for the continuous automatic treatment of washing baths of an installation for the printing and development of photographic films in which said baths (3,4,5) are cascaded, the upstream bath (3) relative in the sense of the cascade being permanently supplied with the washing liquid consisting of water and stabilizer, the downstream bath (5) being provided with an overflow device (9), intended to allow the evacuation of the liquid of excess washing loaded with impurity, characterized in that it comprises:  - a weir (10), connected directly to the overflow device (9) with which the downstream bath (5) is provided, at the level of which the washing effluents from the downstream bath (5) are temporarily stored;  an ion exchange resin (16) at the level of which the effluents stored in the weir (10) are periodically pumped when the latter is full, the deionized water obtained being stored in a storage tank (18),  - a recirculation circuit (20,21,22,23) ensuring the supply and the agitation of the upstream bath (3), comprising a tapping point (20) in said upstream bath, a filter (21), a pump (22) and an injection point (23), said recirculation circuit additionally receiving in a determined quantity of water from the storage tank (18) and from the stabilizer itself stored in concentrated form (24).  5 / Device according to claim 4, characterized in that the injection of deionized water and the stabilizer is managed by a central control unit (28).  6 / Device according to one of claims 4 and 5, characterized in that the weir (10) is provided with a level detector (11), actuating a pump (15) to proceed to its periodic emptying, and to the sending the effluents that said weir (10) stores on the ion exchange resin.