Photographic processing apparatus

Abstract: A photographic processing apparatus including a processing tank unit formed with a small volume for holding a processing solution for processing a continuous web of photographic material is accompanied by a first circulation system having a circulation pump for circulating the processing solution through the tank unit and a second circulation system for mixing a replenisher, supplied through a replenisher supply system, with the processing solution and circulating the mixture through the first circulation system and tank unit.

Description: BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a photographic processing apparatus, and, more particularly, to a continuous web of photographic material processing apparatus which has a simplified structure to enable efficient supply of a replenishing solution to a processing tank. 2. Description of Related Art Typically, photographic material wet processing, including development, bleach, fixation and stabilization, is accompanied by replenishment of a fresh processing solution mixed with auxiliary agents of developer. In order to provide a uniform quality of pictures, photographic materials are immersed in a plentiful processing solution. While using a large quantity of processing solution is advantageous to provide a uniform quality of pictures, nevertheless, various constraints are imposed on keeping desired chemical characteristics of the processing solution. For instance, if only a small quantity of photographic materials are processed in a plentiful processing solution, the processing solution is apt to be oxidized with air, to deteriorate chemical characteristics of its components due to absorption of carbonic acid gas and/or to lower its pH value, which are accompanied by the result of poor quality of pictures. In view of controlling the chemical characteristics of processing solution, a reduction of resources and serving for the maintenance of the environment, it is desired to use a processing solution and replenishing solutions as small in quantity as possible. It has been proved effective on these demands to utilize a processing apparatus of a type having a processing tank and a processing rack, these processing tank and rack being configured so as to form a small volume therebetween for holding a processing solution. For the purpose of providing a brief background of this type of photographic processing apparatus that will enhance an understanding of the operation of a photographic processing apparatus according to the present invention, reference is made to Figure 4 showing a prior art photographic paper processing or developing apparatus. As Figure 4 shows, the photographic paper processing apparatus 100 is equipped with a processing solution circulation system 200 for a circulation of a processing solution through a processing tank 101 while processing photographic paper. The processing solution circulation system 200 includes a pump 205 to force the processing solution out from and into the processing tank 101 through a circulation conduit 204 extending between an inlet nozzle 102 and an outlet nozzle 103 of the processing tank 101. Because the development of great area of photographic paper yields gradual consumption of the processing solution and deterioration in chemical performance of the processing solution, supply of the fresh processing solution including auxiliary agents of developer, which are collectively referred to as a replenisher solution, or otherwise simply as a replenisher, is supplementarily compelled. While the supply of a fresh replenisher through the circulation conduit 204 has the effect of maintaining the processing solution to be fresh and uniform in quality, nevertheless, there are various structural constraints imposed on the circulation system 200. Specifically stating, in the prior art photographic paper processing apparatus 100, the processing tank 101 must be connected with both ends of the inlet and circulation conduit 204, having a small drift space or cross-sectional area, at the spout nozzle 102 and discharge or outlet nozzle 103. This structure causes, on one hand, a sharp decrease in resistance against the processing solution discharged into the circulation conduit 204 through the discharge nozzle 103 and, on the other hand, a sharp decrease in resistance against the processing solution entering the spout nozzle 103 from the circulation conduit 204, resulting in pressure fluctuations of the developing solution in the circulation conduit 204 which is directly reflected on the liquid level of the replenisher in the replenisher tank 300. Resultingly, the circulation system 200 is not in any way allowed to be left open to air in order to make up for lost replenisher. In place of providing an access opening in the circulation conduit 204, the pump 205 is corporated in the circulation system 200 so as to force replenisher supply to the circulation conduit 204 through a filtering case. For the purpose of replenisher supply, because what is called a bellows pump which is simple in structure and relatively inexpensive is unsuitable for the circulation system 200 to supply the replenisher at a high level of pressure, there is a strong demand for high performance pumps, such as of a plunger type and of a diaphragm type which have high pressure discharging performance and are always relatively expensive as compared to the bellows pumps. Further, in order for the circulation system 200 to reduce a pressure difference of the developing solution with respect to the atmospheric pressure caused due to resistance at the spout nozzle 102 and discharge nozzle 203, an orifice is corporate in the circulation conduit 204 with the effect of allowing the circulation conduit 204 to open to air either on the upstream side from or on the downstream side from the orifice and, thereby, supplying a replenisher to the circulation conduit 204 through the opening. This configuration, however, causes an indispensable problem that a restricted flowing rate at the nozzle of the developing solution yields significant aggravation of the efficiency of development. Another prior art photographic processing apparatus intended to use only small quantities of these processing solution and replenisher is disclosed in, for instance, US patent 5,270,762. The approach in reducing the quantity of processing solution used in the US patent 5,270,762 is to dimension a processing tank and a processing rack so as to form a small volume for holding a processing solution and photographic material, which allows to use a reduced quantity of processing solution with the result of suppressing evaporation and deterioration or oxidization of processing solution. The photographic processing apparatuses of this type has the further advantage of miniaturization and simplification of the processing assembly. In many instances where a processing tank and a processing rack are configured and assembled so as to form a small volume therebetween for holding a processing solution, it is still necessary to make up a loss of the processing solution through a replenishing system. Because of a small volume of processing solution servicing in the processing tank, the processing solution is concentrated in the processing tank in close proximity of the inlet due to supply of a fresh replenisher and becomes less in concentration in the processing tank in close proximity of the outlet as the result of deterioration of the processing solution. Further, while the processing solution has strong activity around the inlet, it is less agitated, resulting in an inferior mixture of the servicing processing solution and fresh processing solution overall within the processing tank. In other words, this type of processing tank assembly is apt to be accompanied by the disadvantage of inhomogeneous distribution of the concentration of processing solution in the processing tank, which always leads to developing stain, developing marks and ununiform picture quality. Other prior art photographic processing apparatuses are disclosed in US-A-5 184 164 and FR-A-1 121 741. SUMMARY OF THE INVENTION It is an object of the present invention to provide a photographic processing apparatus which, while utilizing a processing solution as small in quantity as possible, enables supply of a fresh replenisher with a high precision to the processing solution in a circulation system so as to maintain desired quality of the processing solution. It is another object of the present invention to provide a photographic processing apparatus which enables to install a low pressure, fixed displacement pumping means, such as a bellows pump, to a replenishing system. The aforesaid object of the present invention is achieved by providing a photographic processing apparatus as defined in claim 1, for processing a continuous web of photographic materials, such as photographic paper, which has a processing tank unit formed with a small volume for holding a processing solution. The processing tank unit comprises a processing tank and a processing rack which are integrally assembled to form a small volume for holding a processing solution therebetween. Further, the processing rack is formed with small volumes of vertical paths at opposite sides thereof for holding a processing solution and a continuous web of photographic material moving therethrough. Each path is in communication at its bottom with the small volume of the processing tank. The small volumes of these processing tank and paths of the processing rack are connected for circulation of the processing solution through the processing tank assembly by means of a circulation system. The circulation system includes first and second circulation means for circulating the processing solution through the processing tank assembly. The first circulation means includes a first circulation conduit connected between the outlet and the first inlet, and a circulation pumping means installed to the first circulation conduit so as to force the processing solution to flow through the first circulation conduit. The second circulation means includes a second circulation conduit connected between the first circulation conduit upstream from the circulation pumping means and the second outlet for circulating the processing solution through the processing tank assembly and a replenisher vessel in the second circulation conduit for holding a mixture of these processing solution and replenisher. The replenisher vessel is open to the atmosphere and is supplied with a fixed quantity of the replenisher by means of a replenisher supply means every fixed length of the continuous web of photographic material. The replenisher supply means comprising a replenisher tank for containing the replenisher, a replenisher conduit detachably coupled at another end to the replenisher vessel, and pumping means installed to the replenisher conduit for delivering a fixed quantity of said replenisher to the replenisher vessel. The pumping means may preferably employ a fixed displacement pump, such as a bellows type of fixed displacement pump which is always significantly inexpensive as compared with a high outlet pressure plunger type of fixed displacement pumps and a high outlet pressure diaphragm type of fixed displacement pumps. The replenisher vessel is formed with a connecting conduit through which the replenisher vessel opens to the atmosphere and to which the replenisher conduit is detachably coupled. Specifically, the connecting conduit has an inner diameter larger than an outer diameter of said replenisher conduit so as to form a small volume of air space between these connecting conduit and replenisher conduit when coupled. The outlet end of the replenisher conduit is separated from a water head of the processing solution in the replenisher vessel when coupled to the connecting conduit. The separation prevents a flow of solution from the replenisher vessel into the replenisher conduit, providing supply of a precisely controlled quantity of replenisher solution. The second circulation means further includes a restrictor, such as an orifice and a valve, installed to the second circulation conduit downstream from the replenisher vessel for restricting a flow rate of the processing solution in the second circulation conduit. According to the photographic processing apparatus of the present invention, the first circulation means causes a negative pressure in the circulation conduit upstream from the circulation pumping means by means of which induces circulation of a mixture of the processing solution and fresh replenisher in the replenisher vessel through the processing tank assembly. The utilization of the replenisher vessel open to the atmosphere to the second circulation means enables both processing solutions in the processing tank assembly and replenisher vessel to be at an approximately same pressure level, the restrictor can develop pressure relatively lower downstream therefrom than upstream therefrom. This pressure difference enables the utilization of a relatively low outlet pressure type of fixed displacement pumping means, such as a bellows type of pump which has a necessary accuracy of operation and is furnished at low costs. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the present invention will be clearly understood from the following description with respect to a preferred embodiment thereof when considered in conjunction with the accompanying drawings, in which: Figure 1 is a schematic overall view, partly in cross-section, of a photographic processing apparatus according to a preferred embodiment of the present invention; Figure 2 is a vertical-sectional view of a processing tank unit of the photographic processing apparatus shown in Figure 1; Figure 3 is an enlarged perspective view of a replenisher vessel of the processing apparatus of Figure 3; and Figure 4 is a schematic overall view, partly in cross-section, of a prior art photographic processing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Parts which are not of direct importance to the invention and parts which are purely of conventional construction will not be described in detail. For example, details of the processing unit and its associated elements which are necessary for the photographic processing apparatus will not been set out in detail since their construction and operation can easily be arrived at by a person skilled in the art. Referring to the drawings in detail, in particular to Figure 1 showing a photographic processing or processing apparatus according to a preferred embodiment of the present invention, the photographic processing apparatus 1, such as a photographic paper processing or developing apparatus for processing a continuous web of exposed photographic paper, comprises a paper processing unit 1A, which is a main part of the processing apparatus 1, a first or primary processing solution circulation system 1B, a second or secondary processing solution circulation system 1C and a replenisher supply system 1D. As shown in detail in Figure 2, the processing unit 1A includes a processing tank 11 and a processing rack 21, which are configured such that the processing rack 21 is removably inserted into the processing tank 11. The processing tank 11, which is open at the top and closed at the bottom, has an inlet 12 near the open top end 11c in each side wall 11a and a side outlet 13a below the inlet 12 in each side wall 11a. Further, the processing tank 11 has a bottom outlet 13b formed in a bottom wall 11 b. The processing rack 21 has paper paths 22, each extending from the top to the bottom at each side of the processing rack 21 and being in communication with a space of the processing tank 11 at the bottom. A continuous web of exposed photographic paper is introduced into one of the paper paths 22 by means of feed rollers 26, passes between a transport roller 27 and idle rollers 28, is moved upward in another paper path 22 and is finally taken out of the processing tank 11 by means of take-out rollers 29. Further, the processing rack 21 has a solution spout means 23 in each of outer walls 21a through which a processing solution is injected into the paper path 22. A processing solution, which is introduced into each paper path 22 through the solution spout means 23, flows down in the paper path 22 and is discharged out of the paper path 22 and the processing tank 11 through the bottom outlet 13b. These processing tank 11 and processing rack 21 are designed and configured such that, when the processing rack 12 is inserted in position, the solution spout means 23 are in alignment with the inlets 12, respectively, and a small volume of space 15 is provided between the processing tank 11 and processing rack 21. While the solution spout means 23 may be of a type of elongated slit nozzle 23a, it is not limited to a slit type nozzle and may take any known type of aperture having an effective area relatively smaller than a cross-sectional area of a circulation conduit 31 forming a part of the primary processing solution circulation system 1B (which will be described in detail later). In Figure 1, the primary processing solution circulation system 1 B includes a primary circulation conduit 31 comprising an upstream circulation conduit 31a coupled at its one end to the bottom outlet 13b of the processing tank 11 and at another end to a circulation pump 32 and a downstream circulation conduit 31b coupled at its one end to the circulation pump 32 and at another end to each inlet 12 of the processing tank 11. The secondary processing solution circulation system 1C includes a secondary circulation conduit 33 comprising a downstream circulation conduit 33a branching off from the upstream circulation conduit 31 a provided with a restrictor or metering valve, such as an orifice 34, and coupled to a replenisher vessel 35 open to the atmosphere, such as a manifold, and an upstream circulation conduit 33b extending from the replenisher vessel 35 and coupled to each of the side outlets 13a. The circulation pump 32, such as a positive displacement type of magnet pump, can deliver outlet pressure between 2.94 x 10 4 and 5.88 x 10 4 Pa (which is equivalently between 0.3 and 0.6 kgf/cm 2 ). Referring to Figures 1 and 3, the replenisher vessel 35 has a volume to contain replenisher of approximately 10 to 50 ml and is formed with at least one, practically four in this embodiment, connecting conduits 35a - 35d. While the replenisher vessel 35 is open to the atmosphere through these connecting conduits 35a - 35d, various solutions, for instance a developing agent, preservative, a contamination inhibitor and a hardening agent, are supplied independently through these connecting conduits 35a - 35d, respectively, by means of the replenisher supply system 1 D. Specifically, the replenisher supply system 1 D includes first to fourth (#1 to #4) replenisher tanks 41a- 41d, each replenisher tank 41a- 41d being coupled to one of the connecting conduits 35a - 35d of the replenisher vessel 35 by means of a replenisher conduit 42a - 42d. Each replenisher conduit 42a - 42d is provided with a pump 43a - 43d, desirably a fixed displacement pump, for delivering a fixed quantity of solution into the replenisher vessel 35. As clearly shown in Figure 3, the replenisher conduit 42a - 42d and the connecting conduit 35a - 35d are designed and configured such that, they are easily detachably coupled to each other and, when they are coupled, there is formed a cylindrical air space therebetween sufficiently thick to enable the replenisher vessel 35 to be kept open to the atmosphere. In other words, the connecting conduit 35a - 35d has an outer diameter sufficiently greater than an inner diameter of the replenisher conduit 42a - 42d. It is to be noted that the outlet end of each replenisher conduit 42a - 42d is separated from the level of processing solution in the replenisher vessel 35 so that the processing solution in the replenisher vessel 35 does not flow into the replenisher conduit 42a - 42d. The fixed displacement pump 43a - 43d is activated when a predetermined area of exposed photographic paper is processed to supply a fixed quantity of an auxiliary agent forming part of the replenisher to the replenisher vessel 35. The processed area of photographic paper may be represented by a forwarded length of the photographic paper which is measured by a measuring device (not shown) well known in the art. Quantities of these solutions to be periodically supplied are not always equal and determined according to processing conditions including types and sizes of photographic papers. The replenisher is mixed with the processing solution in the replenisher vessel 35. Because the replenisher vessel 35 is open to the atmosphere, the internal pressure of the replenisher vessel 35 is approximately equal to the atmospheric pressure, the processing solution in the processing tank 111 and the replenisher in the replenisher vessel 35 are at the approximately same level. The processing solution mixed with the replenisher is discharged into the upstream circulation conduit 31 a of the primary circulation system 1 B through the downstream circulation conduit 33a of the secondary circulation system 1 C via the orifice 34. As is well known, the orifice 34 works as a restrictor to cause a pressure drop in a flow of discharged solution in the primary circulation conduit 31. Another type of restrictor, such as a metering valve, may be installed in place of the orifice 34. Such a metering valve is installed with the effect of always optimizing supply of the replenisher through regulating opening of the valve according to processing circumstances including, for instance, the outlet pressure of circulation pump 35, types of replenisher solutions and the atmospheric pressure. Each of the fixed displacement pumps 43a - 43d has a relatively low outlet pressure of, for instance, 4.9 x 10 3 to 9.8 x 10 3 Pa (which is equivalent to 0.05 to 0.1 kgf/cm 2 ). The fixed displacement pumps 43a - 43d may be of a bellows type or a diaphragm type which satisfies a demand for required accuracy and is, however, always inexpensive. In supplying the replenisher solution into the photographic processing apparatus shown in Figures 1 to 3, when the circulation pump 32 is actuated, a processing solution in the processing tank 11 is circulated flowing through the upstream circulation conduit 31a via the bottom outlet 13b of the processing tank 11 and the downstream circulation conduit 31b, and forced into the processing tank 11 through the solution spout means 23. While the processing solution is circulated by means of the primary circulation system 1B, a negative pressure is created in the primary circulation conduit 31 in the upstream proximity of the circulation pump 32, i.e. in the upstream circulation conduit 31a, which causes circulation of the processing solution through the secondary circulation system 1C. During this circulation, the processing solution mixed with the replenisher in the replenisher vessel 35 is forced to flow into the upstream circulation conduit 31 a in the aid of the negative pressure and to mix with the processing solution which has been degraded to a certain extent. While the processing solution is circulated by means of the primary and secondary circulating systems 1B and 1C, the exposed photographic paper is continuously moved through the paper paths 22 filled with the processing solution which is agitated due to the circulation. Progress of processing the exposed photographic paper causes gradual consumption of the processing solution in the processing tank 11. When there is a demand for making up the loss, in other words, when the measuring device detects the predetermined length of exposed photographic paper, the fixed displacement pumps 43a - 43d are actuated automatically to supply the replenisher into the replenisher vessel 35 from the replenisher tanks 41a- 41d through the replenisher conduits 42a - 42d, respectively. In order for the processing solution in the processing tank unit 1A to be more uniform in concentration distribution, an auxiliary circulation conduit 31c may be installed between the processing tank 11 and the first circulation conduit 31 upstream from the circulation pump 32. Further, the first and second circulation may be furnished independently for each of different auxiliary agents of developer, with a significant effect in many instances where counter flow tanks are installed. It is to be understood that although the present invention has been described with regard to preferred embodiments thereof, various other embodiments and variants may occur to those skilled in the art, which are within the scope of the invention, and such other embodiments and variants are intended to be covered by the following claims.

Claims: A photographic processing apparatus (1) for processing a continuous web of photographic material, said photographic processing apparatus including a processing tank unit (1A) filled with a processing solution in which said continuous web of photographic material is processed and circulation means for circulating said processing solution through said processing tank unit, said circulation means comprising; a first circulation system (1B) for circulating said processing solution through said processing tank unit comprising a first circulation conduit (31) connected between a bottom solution outlet (13b) and a first solution inlet (12) of said processing tank unit and circulation pumping means (32) installed to said first circulation conduit so as to force said processing solution to flow through said first circulation conduit; characterised by a second circulation system (1c) for circulating said processing solution through said processing tank unit, comprising a second circulation conduit (33) connected to said first circulation conduit upstream from said circulation pumping means and to a second outlet (13a) of said processing tank unit located between the first inlet and the bottom outlet, on a side wall of said processing tank unit and a replenisher vessel (35) installed in said second circulation conduit for holding a mixture of said processing solution and a replenisher solution, said replenisher vessel being open to the atmosphere; and replenisher supply means (41a-41d, 42a-42d, 43a-43d) for supplying a fixed quantity of said replenisher solution to said replenisher vessel. A photographic processing apparatus as defined in claim 1, further comprising means for monitoring a processed area of said continuous web of photographic material and actuating said replenisher supply means to supply said replenisher solution to said replenisher vessel when detecting a specified total processed area of said continuous web of photographic material. A photographic processing apparatus as defined in any one of said preceding claims 1 and 2, wherein said replenisher supply means comprising a replenisher tank (41a-41d) for containing said replenisher, a replenisher conduit (42a-42d) connected at one end to said replenisher tank and detachably coupled at another end to said replenisher vessel, and pumping means (43a-43d) installed to said replenisher conduit for delivering a fixed quantity of said replenisher solution to said replenisher vessel. A photographic processing apparatus as defined in claim 3, wherein said pumping means comprises a fixed displacement pump. A photographic processing apparatus as defined in claim 3, wherein said pumping means comprises a bellows type of fixed displacement pump. A photographic processing apparatus as defined in any one of said preceding claims 1 to 5, wherein said replenisher vessel is formed with a connecting conduit through which said replenisher vessel opens to the atmosphere and to which said replenisher conduit is detachably coupled. A photographic processing apparatus as defined in claim 6, wherein said connecting conduit (35a-35d) has an inner diameter larger than an outer diameter of said replenisher conduit so as to form an air space between said connecting conduit and said replenisher conduit when coupled. A photographic processing apparatus as defined in claim 6, wherein the outlet end of said replenisher conduit is separated from a water head of said processing solution in said replenisher vessel when coupled to said connecting conduit. A photographic processing apparatus as defined in any one of said preceding claims 1 to 8, wherein said second circulation means further includes a restrictor (34) installed to said second circulation conduit downstream from said replenisher vessel for restricting a flow rate of said processing solution in said second circulation conduit. A photographic processing apparatus as defined in claim 9, wherein said restrictor comprises an orifice. A photographic processing apparatus as defined in claim 9, wherein said restrictor comprises a valve. A photographic processing apparatus as defined in any one of said preceding claims 1 to 11, wherein said processing tank unit comprises a processing tank (11) and a processing rack (21), said processing rack being formed with vertical paths (22) extending from the top to the bottom at opposite sides thereof, said paths holding said continuous web of photographic material moving therethrough and being in communication at their bottom with said processing tank so as to enable said processing solution to circulate. A photographic processing apparatus as defined in claim 12, further comprising solution spout means (23) installed to said processing rack in communication with said first circulation conduit via said first inlet and said paths. A photographic processing apparatus as defined in claim 13, wherein said solution spout means comprises a slit type of nozzle. A photographic processing apparatus as defined in claim 13, wherein said processing rack and said processing tank are configured so as to form a narrow space (15) therebetween for holding said processing solution. A photographic processing apparatus as defined in claim 15, wherein said second outlet is in communication with said processing tank. A photographic processing apparatus as defined in claim 1, wherein said replenisher supply means supplies independently a plurality of auxiliary agents and a fresh processing solution as said replenisher. A photographic processing apparatus as defined in claim 17, wherein said replenisher comprises a developing agent, preservative, a contamination inhibitor and a hardening agent.

Inventors: KINOSHITA TOGO, KINOSHITA, TOGO
Applicants: NORITSU KOKI CO LTD, NORITSU KOKI CO., LTD.
Application year: 1996
Main classification: G03D3
IPC codes: G03D3