Photographic process with improved replenishment monitoring system

A method and apparatus for processing a photosensitive material. The apparatus includes at least one processing section and a replenishment system for delivering replenishment solution contained within a container to the processing section. The replenishment system including a single device for withdrawing replenishment solution from the container and for monitoring the level of the replenishment solution contained in the container. The container is made of a material that is electrically non-conductive. A pair of spaced electrically conductive members are provided within the container. One of the members has a passageway for allowing withdrawal of the replenishment solution from the container and has a terminal end which extends below the other member within the container. An AC current is applied to the pair of spaced members and the AC current is monitored with a level sensing circuit. When the replenishment solution falls below the end of the shorter member, a low level indicating signal is produced by the level sensing circuit.

FIELD OF THE INVENTION 
The present invention relates to a photographic processor, and more 
particularly, to a method and apparatus for monitoring the liquid level 
and dispensing of photographic processing solution from a replenishment 
container. 
BACKGROUND OF THE INVENTION 
In photographic processors it is important to know whether there is a 
sufficient supply of replenishment solution in the replenishment container 
from which the replenishment solution is being drawn. If there is too 
small of an amount of replenishment solution remaining in the supply 
container, then there exist the danger of drawing air into the 
replenishment system. This is very undesirable for a number of reasons. If 
air is drawn into the replenisher pump this can result in damage to the 
pump, or an air lock to occur which will prevent replenishment solution 
from being supplied which will then affect the overall chemical balance of 
the processing solution. Additionally, the presence of air in certain 
processing solutions, such as developer, can result in undesirable 
oxidization which will break down the processing solution and 
significantly affect the effectiveness of the processing solutions. 
Therefore, it is important to properly monitor the liquid level of the 
replenishment solution in the replenishment container. It is known to 
monitor an AC current applied to probes placed in the container holding 
replenishment solution for mounting the level of the liquid. 
It is also necessary to provide an appropriate system for withdrawing the 
replenishment solution from the replenishment container. The system must 
be resistant to the corrosive effects of the processing solution. It is 
also desirable to minimize the cost of the system without sacrificing the 
reliability of the system. 
Applicants have invented an improved liquid level sensing and delivery 
system which can be used in corrosive environmental applications such as 
that found in photographic processors for providing accurate information 
upon which replenishment liquid level can be monitored and for the 
dispensing of the replenishment from the replenishment container. The 
system is Of simple design and construction, low cost to manufacture, and 
easy to assembly. 
SUMMARY OF THE INVENTION 
In one aspect of the invention there is provided an apparatus for 
processing a photosensitive material. The apparatus includes at least one 
processing section and a replenishment system for delivering replenishment 
solution contained within a container to the processing section. The 
replenishment system includes a single means for withdrawing replenishment 
solution from the container and for monitoring the level of the 
replenishment in the container. 
In another aspect of the present invention there is provided a method for 
withdrawing a replenishment solution contained within a container and for 
monitoring the level of the replenishment solution within the container. 
The container is made of a material that is electrically non-conductive. 
The method comprises the steps of: 
providing a first electrically conductive rod within the container and a 
spaced second electrically conductive tube within the container, the tube 
having a passageway for allowing withdrawal of the replenishment solution 
from the container, the tube extending below the rod within the container; 
applying an AC current to the rod and the tube; 
monitoring the AC current with a level sensing circuit; and 
producing a low level indicating signal based on the monitoring of the AC 
current.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, there is illustrated a processing apparatus 10 for 
processing photosensitive material made in accordance with the present 
invention. The processing apparatus 10 includes a processing section 12 
wherein photosensitive material is subjected to a photoprocessing solution 
and a recirculation system 14 (as best seen in FIG. 2) for recirculating 
processing solution through the processing section 12. 
In the particular embodiment illustrated in FIG. 1, the recirculation 
system 14 includes a pump 16 which is connected to the outlet 17 of 
processing section 12 by first conduit 18. The recirculation system 
further includes a manifold 20, a filter unit 22, and a heater 24. The 
pump 16 is fluidly connected to manifold 20 by a second conduit 26 and the 
manifold 20 is fluidly connected to filter unit 22 by a third conduit 28. 
A fourth conduit 30 fluidly connects the output of the filter unit 22 to 
the input of heater unit 24 and the output of the heater 24 is fluidly 
connected to the processing section 12 by a fifth conduit 32. Thus, 
processing solution can flow from the output 17 of the processing section 
through first, second, third, fourth and fifth conduits returning to the 
inlet 33 of the processing section. 
The manifold 20 serves as a means for introducing replenishment solution 
from a reservoir 34 into the recirculation system 14. The reservoir 34 is 
fluidly connected to the manifold by appropriate sixth conduit 36. 
Replenishment solution is introduced from the reservoir 34 to manifold 20 
by pump 38. As is typical with photographic processors, a CPU 40 (central 
processing unit/computer) is provided for controlling the operation of the 
apparatus. As is illustrated, the central processing unit 40 is connected 
to pumps 16,38 and to sensor 42 provided in the processing section 12. The 
sensor 42 is a liquid level sensor for sensing when additional processing 
solution is required. Recirculation system 14 includes a flow monitoring 
sensor 46 which is used to determine if processing solution is properly 
flowing through the processing recirculation system 14. 
Referring to FIG. 2, there is shown a perspective view of a portion of the 
processing apparatus 10 illustrating the processing section 12 and 
recirculation system 14. In the particular embodiment illustrated, the 
processing section 12 includes four separate developing sections 
47,48,49,50, each designed to contain a different processing solution. In 
particular, development section 47 is designed to hold a developer 
solution, developing section 48 is designed to hold a bleach fixed 
solution, and sections 49,50 are designed to hold rinse and wash 
solutions. Each of the processing sections include a recirculation system 
14 as described and illustrated in FIG. 1, but for the sake of clarity, 
only a single recirculation system is illustrated in FIG. 2, it being 
understood that each of these processing sections have a recirculation 
system 14 as described and illustrated. A drying section 52 is provided 
after the processing section wherein the photosensitive material is dried 
prior to exiting slot 54. In the particular embodiment, a pair of outlets 
17 are fluidly connected to conduit 18. Reservoir 34 is fluidly connected 
to replenishment pump 38 by conduit 39. Pump 38 draws replenishment 
solution from reservoir 34 and delivers it to manifold 20 through conduit 
36. 
Referring to FIG. 3, there is illustrated in greater detail the reservoir 
34 made in accordance with the present invention. In particular, the 
reservoir 34 comprises a container 60 for holding a replenishment solution 
62. As is typical, replenishment solution 62 is electrically conductive. 
The container is provided with a generally cylindrical neck portion 64 
having an access opening 68 for dispensing and/or filling of replenishment 
solution 62 in container 60. A lid 70 is provided for engaging the neck 
portion 64 covering access opening 68. The use of lid 70 avoids spilling 
and minimizing oxidation of the replenishment solution 62. The container 
60 and lid 70 are made of a non-conductive material, for example, plastic. 
In the embodiment illustrated, container 60 and lid 70 are made of 
polypropylene. 
The apparatus 10 includes means for monitoring the level of the 
replenishment solution 62 within the container 60 and for withdrawing of 
the replenishment solution 62. In particular, a first level sensing rod 
72, of a first predetermined length L1, is provided for placement in 
container 60 and has an upper end 74 which is secured to lid 70 by any 
conventional technique. Thus, the first level sensing rod 72 is mounted in 
a stationery position with respect to container 60. Rod 72 is made of a 
conductive and corrosive resistant material. In the embodiment 
illustrated, rod 72 is made of an electrically conductive stainless steel. 
Referring to FIG. 5, there is illustrated in greater detail how rod 72 is 
secured to lid 70. Rod 72 is provided with internal threads 76 for 
engaging the external threads 78 of electrically conductive mounting screw 
80. Mounting screw 80 passes through an opening 82 in lid 70. An 
electrical ring terminal 84 having an opening 83 is provided and 
positioned for placement between the head 88 of screw 80. An electrical 
wire 90 has end 92 connected to terminal 84. The other end of the wire 90 
is connected to an electronic control board (not shown) through connector 
93 (see FIG. 3) which is controlled by CPU 40. When screw 80 is threaded 
into rod 72 it will cause the rod 72 to be secured to the lid 70 while 
also clamping the terminal 84 to the lid 70 and providing electrical 
connection to rod 72. 
The means for monitoring the level of the processing solution within the 
container 60 and for withdrawing of the replenishment solution 62 further 
includes a second level sensing tube 96 (see FIG. 6) of a second 
predetermined length L2 and has an upper end 98 which is secured to lid 70 
by any conventional technique. Thus, the robe 96 is also mounted in a 
stationary position with respect to the container 60. Tube 96 has an 
internal passage 97 which extends through the length L2 and terminates in 
an inlet opening 101 for drawing replenishment solution 62 therein. The 
tube 96 is made of a conductive and corrosive resistant material, and in 
the particular embodiment illustrated, is made of an electrically 
conductive stainless steel. Referring to FIG. 6, there is illustrated in 
Greater detail how tube 96 is secured to lid 70. Tube 96 is provided with 
internal threads 100 for engaging the external threads 102 of electrically 
conductive mounting fitting 104. Mounting fitting 104 passes through an 
opening 106 in lid 70. An electrical ring terminal 108 having an opening 
110 is provided and positioned for placement between the head 112 of 
fitting 104. An electrical wire 114 has end 116 connected to terminal 108. 
The other end of the wire 114 is connected to an electronic control board 
(not shown) also through connector 93, which is controlled by CPU 40. When 
fitting 104 is threaded into tube 96, it will cause the tube 96 to be 
secured to the lid 70 while also clamping the terminal 108 to the lid 70 
and providing electrical connection to tube 96. The fitting has an 
internal passage 99 which is in fluid communication with the passage 97 of 
tube 96. Conduit 39 is fluidly connected to fitting 104. 
A level sensing circuit 120 is connected to other ends of wires 90,114 and 
provides an AC current through tube 96 and rod 72. The level sensing 
circuit 120 sends a monitoring signal to CPU 40 which is representative of 
the presence of the replenishment solution 62 in container 60. AC current 
is used so as to prevent plating of the rod 72 and tube 96. Any 
appropriate amount of current may be applied to rod 72 and tube 96. In the 
particular embodiment illustrated, AC current in the range of about 200 to 
300 microamps are applied. 
In order to more clearly understand the present invention, a description of 
its operation will now be discussed. First a container 60 which is filled 
with a replenishment solution 62 is provided. The lid 70 with secured rod 
72 and tube 96 is placed on neck 64. The length L2 of tube 96 is greater 
in length than the length L1 of rod 72. The length L2 is such that opening 
101 is closely adjacent the bottom 61 of container 60. The level sensing 
circuit 120 (see FIG. 1) is activated so as to provide an AC current 
through rod 72, tube 96 and replenishment solution 62. Since replenishment 
solution 62 is electrically conductive, a signal will be detected by the 
level sensing circuit 120 as long as the replenishment solution completes 
the electrical connection between the rod 72 and tube 96. In the 
embodiment illustrated, the level sensing circuit 120 is an LM1830 
integrated circuit which may be purchased from a typical electronic 
supplier, such as the National Semiconductor Corporation. When the level 
of the replenishment solution 62 falls below the bottom end 122 of rod 72, 
the AC current is interrupted causing the level sensing circuit 120 to 
detect a change in condition which is representative of the lack of 
presence of the replenishment solution, that is, the level of the 
replenishment solution 62 is below end 122. The level sensing circuit 120 
then sends an appropriate signal to CPU 40 which in turn turns off pump 
38. If desired, an alarm or signal may be provided for notifying an 
operator of the condition of the liquid level in the container 60. The 
length L1 and L2 are selected so that most of the replenishment solution 
will have been removed from container 60, yet having a difference in 
length D is such that the pump 38 will be turned off prior to taking air 
into tube 96. In the particular embodiment illustrated, the difference in 
length between L1 and L2 is approximately 1/4 inches (0.632 cm). However, 
the difference may be any desired amount so long as it provides the 
As can be seen, the present invention not only provides means for supplying 
replenishment solution, but also provides means for sensing the level of 
fluid. Additionally, the system is relatively simple in construction, low 
cost, and very reliable. 
Referring to FIG. 4, there is illustrated a modified form of the present 
invention. This system is similar to that of FIG. 2, like numerals 
indicating like parts and operation, previously described, and is 
incorporated herein. In this embodiment there is provided an automatic 
quick disconnect assembly 130 for allowing quick disconnect of the 
electrical wires 90,114. In this embodiment wires 90,114 are connected to 
electrical terminals 132,134, respectively, on an electrical mounting 
plate which is secured to apparatus 10. A pair of electrical conductive 
spring members 138,140 are secured to mounting plate 136. Each spring 
member 138,140 has a flexible lower spring end 142,144 which contact 
terminals 84,108, respectively, when the container is properly seated in 
apparatus 10. Members 138,140 each have an upper portion 146,148, 
respectively, which are designed to contact terminals 132,134 on plate 
136. Thus, there is provided electrical connection between rod 72, tube 
96, and wires 90,114, respectively. When the container 60 is removed from 
apparatus, the lower ends 142,144 deflect so as to allow removal of the 
container. Likewise, the members flex to allow insertion of a freshly 
filled container 60. In this manner no manual electrical disconnection of 
wires 90,114 is required. Electrical connection is automatically made 
simply by proper positioning of the container 60. Once conduit 39 is 
disconnected from fitting 104, the container is simply removed for 
refilling and/or replacement. 
The present invention provides an improved flow monitoring system which is 
low cost, accurate, and is not subject to corrosive effects of the 
processing solution. 
It is to be understood that various changes and modifications may be made 
without departing from the scope of the present invention, the present 
invention being defined by the claims that follow. 
Parts List: 
10 . . . processing apparatus 
12 . . . processing section 
14 . . . recirculation system 
16,38 . . . pump 
17 . . . outlets 
18 . . . first conduit 
20 . . . manifold 
22 . . . filter unit 
24 . . . heater 
26 . . . second conduit 
28 . . . third conduit 
30 . . . fourth conduit 
32 . . . fifth conduit 
33 . . . inlet 
34 . . . reservoir 
36 . . . sixth conduit 
39 . . . conduit 
40 . . . CPU 
42 . . . sensor 
46 . . . flow monitoring sensor 
47,48,49,50 . . . developing sections 
52 . . . drying section 
54 . . . exiting slot 
60 . . . container 
61 . . . bottom 
62 . . . replenishment solution 
64 . . . neck portion 
68 . . . access opening 
70 . . . lid 
72 . . . first level sensing rod 
74 . . . upper end 
76 . . . internal threads 
78 . . . external threads 
80 . . . mounting screw 
82,83 . . . opening 
84 . . . electrical ring terminal 
88 . . . head 
90,114 . . . electrical wire 
92 . . . end 
93 . . . connector 
96 . . .second level sensing tube 
97,99 . . . internal passage 
98 . . . upper end 
100 . . .internal threads 
101. . . opening 
102 . . . external threads 
104 . . . mounting fitting 
106 . . . opening 
108 . . . electrical ring terminal 
110 . . . opening 
112 . . . head 
116 . . . end 
120 . . . sensing circuit 
122 . . . bottom end 
130 . . . disconnect assembly 
132,134 . . . electrical terminals 
136 . . . mounting plate 
138,140 . . . spring members 
142,144 . . . flexible lower spring end 
146,148 . . . upper portion