Method of and system for controlling edge of distributed processing fluid

A method of and system for supplying processing material to a photographic sheet so as to control material supplied thereto are disclosed. Included in the method are the steps of supplying processing material to the photographic sheet; and detecting a reference area on the sheet. The detecting step includes transmitting at least a beam of measured energy to the reference area and generating a signal responsive to a change in a measured characteristic of the reflected beam from the area which signal is representative of material being present or absent in the area. The output of processing material supplied is varied to the sheet responsive to the generated signal so as to restore the reference area to its condition before the signal.

BACKGROUND OF THE INVENTION 
The present invention relates generally to a method of and apparatus for 
controlling the supply of fluid. More particularly, this invention relates 
to a method of and apparatus for controlling the edge of processing fluid 
distributed between a pair of converging sheets, just prior to the sheets 
becoming superposed to each other. 
A variety of photographic processes of the self-developing type broadly 
involve the application of a viscous liquid reagent across exposed 
photographic sheet material. Typically, in these processes, a 
photosensitive sheet is first exposed and then later superposed with 
respect to a second sheet. The two superposed sheets are then moved 
between a pair of juxtaposed pressure applying members. The pressure 
applying members are constructed and arranged so as to spread the fluid 
from this mass, in an approximately uniform layer, over a desired exposed 
portion of one of the sheets. The spread processing fluid can initiate 
formation of visible images. 
Significant problems can arise in connection with distributing the fluid in 
such a manner. One is to maintain a sufficient amount of fluid over the 
exposed areas of a sheet. This is for the obvious reason that it is 
critical for complete image formation that the amount of processing fluid 
be accurately and uniformly spread out over such exposed area. Secondly, 
it is also important to contain the processing fluid within the desired 
confines of the side marginal edges of the sheets. Otherwise, of course, 
processing fluid falling beyond such edges would contaminate the pressure 
applying rollers and other equipment associated with the processing of the 
photosensitive sheets. Variations in the amount of processing fluid 
distributed at any given time can arise in situations wherein the 
viscosity of the fluid changes. Thus, when attempting to dispense 
controlled amounts of such fluid, these variations can increase or 
decrease the amount dispensed. Thus, significant problems can arise in 
trying to keep the lateral edge of the fluid from spilling off the lateral 
edges of the sheet while insuring that the fluid covers the exposed area 
for complete developing. Such considerations are particularly crucial when 
it is desired to process large quantities of film and there is a 
relatively narrow space between the lateral margins and exposed areas of 
the sheets. 
There have been a number of approaches for controlling the distribution of 
such processing fluid. One makes provision for having side rails on a film 
sheet which are capable of confining excess liquid within the side 
marginal edges. Another solution, disclosed in U.S. Pat. No. 3,120,794, 
describes one of the processing rollers having a pair of axially spaced 
apart sealing elements for purposes of confining the dispensed fluid 
within the side margins of the sheets. U.S. Pat. No. 3,307,467 discloses 
spring-biased pressure applying members which prevent escape of the liquid 
from between the lateral margins of the sheets as the sheets are advanced 
through a gap between the pressure applying members. U.S. Pat. No. 
4,162,834 discloses a pair of laterally spaced nozzle members which direct 
streams of air at opposite ends of a longitudinal processing fluid puddle. 
U.S. Pat. No. 2,563,343 discloses an approach for controlling the supply 
of processing fluid within the marginal edges. In this approach, a liquid 
gauging system is provided which, in one mode, includes a pair of spaced 
electrical contacts. Each one is positioned adjacent a lateral marginal 
edge of a liquid holding space. The contacts are pressed against the edges 
of one of the two sheets being superposed. Normally, the contacts do not 
touch the processing fluid. However, when an excess amount of liquid 
exists within the holding space, it tends to contact both switches. As 
this happens, an electrical connection is created between the two contacts 
for causing operation of a solenoid so as to open a switch. The switch is 
then responsible for operating a valve which restricts the fluid 
dispensed. U.S. Pat. No. 2,719,789 discloses a similar process by which 
liquid is prevented from going beyond the lateral marginal edges of the 
processing sheets. Disclosed is the fact that one of the film sheets is 
provided with a succession of conducting strips along each lateral 
marginal edge. The strips cooperate with spaced apart brushes so as to 
form part of an electrical control circuit. When fluid covers both 
conducting strips, the circuit is operative to control a solenoid which, 
in turn, controls a valve for restricting fluid flow. 
None of the foregoing approaches, however, disclose a system which can 
simply and conveniently control distribution of processing fluid to an 
area adjacent a marginal edge of a photographic sheet, let alone one which 
can reliably control the edges of fluid distributed within a preselected 
zone of the sheet wherein one edge of the zone is adjacent a marginal edge 
of the sheet and an opposite edge of the zone is adjacent a preselected 
portion of the sheet. 
SUMMARY OF THE INVENTION 
According to the present invention, there is provided an improved method of 
and apparatus for controlling the supply of processing fluid to a 
photographic sheet. Included in the method are the steps of supplying 
processing material to the photographic sheet and detecting a reference 
area on the sheet. In the detecting step at least a beam of measured 
energy is transmitted to the reference area and a signal is generated 
responsive to a change in a measured characteristic of the reflected beam 
from the area. This signal is representative of material being present or 
absent in the area. The method includes the step of varying the output of 
processing material supplied to the sheet responsive to the generated 
signal so as to restore the reference area to its condition before the 
signal. 
In an illustrated embodiment of another method of distributing processing 
fluid to a photographic sheet, such method controls the edge of fluid 
distributed within a preselected zone on the sheet. One edge of the zone 
is adjacent a marginal edge of the sheet and an opposite edge of the zone 
is adjacent a preselected portion of the sheet. The method includes the 
step of distributing processing fluid to the photographic sheet so that 
the edge of the fluid is flowable to the zone. A reference area within the 
zone is detected by transmitting at least a beam of measured energy to the 
reference area and generating alternate first and second signals 
responsive to the material interrupting and not interrupting; 
respectively, the beam in the area. Alternately, the output of processing 
fluid being distributed to the sheet is increased and decreased in 
response to alternate ones of said first and second signals so that the 
edge of the fluid remains in the preselected zone. 
The invention contemplates that the beam of energy is infrared energy and 
which is non-actinic relative to the photographic sheet. 
The invention includes a system for supplying processing material to a 
photographic sheet so as to control material supplied. Included in the 
system is means for supplying processing material to the photographic 
sheet material and means for detecting a reference area on the sheet. The 
detecting means includes means for transmitting at least a beam of 
measured energy to the reference area and for generating a signal 
responsive to a change in a preselected measured characteristic of the 
reflected energy from the area which change is representative of material 
being present or absent in the area. Responsive to the signal is means for 
varying the output of the processing fluid supplied to the sheet so as to 
restore the reference area to its condition before the change therein by 
the fluid which caused the change in the measured characteristic of the 
reflected energy. 
Among the objects of the invention are, therefore, the provision of an 
improved method and system for controlling the supply of processing 
material to a photographic sheet; the provision of an improved method of 
and apparatus for controlling processing fluid along a marginal edge of 
the sheet; the provision of an improved method of and apparatus for 
automatically controlling the edge of processing fluid wihtin a zone on 
the sheet wherein one edge of the zone is a lateral marginal edge of the 
sheet and another edge of the zone is adjacent a photographically exposed 
zone of the sheet; the provision of an improved method of and apparatus of 
the above type in which a change in the measured characteristics of a 
reflected beam of energy is indicative of the presence or absence of fluid 
in a reference area in said zone; the method and apparatus of the above 
type which uses energy which is non-actinic to the sheet; and, the method 
and apparatus of the above type in which a single beam of energy controls 
the edge of fluid adjacent both lateral margins of the sheet. 
Other objects and further scope of applicability of the present invention 
will become apparent from the detailed description to follow when taken in 
conjunction with the accompanying drawings wherein like parts are 
indicated by like reference numerals throughout the several views.

DETAILED DESCRIPTION 
Reference is now made to FIGS. 1-3 for showing a processing fluid control 
system 10 which selectively distributes processing fluid 12 in the form of 
a puddle 14 to and between a pair of converging photographic type 
image-receiving and image-forming sheets 16 and 18, respectively. The 
sheets 16, 18 are drawn along converging paths by a conventional type of 
processing assembly, indicated generally by reference numeral 20. Only the 
pair of pressure applying rollers 22 and 24 are shown. The processing 
assembly 20 does not form an aspect of the present invention, thus a 
detailed description thereof has been dispensed with. Only those portions 
of the processing assembly 20 necessary for an understanding of the 
present invention will be described. 
In this embodiment the photosensitive negative image-forming sheet 18 is of 
the type having a plurality of layers including a photosensitive layer, 
which has been photographically exposed previously in a camera, and which, 
of course, carries the latent images thereon. The positive or 
image-receiving sheet 16 is made of a flexible sheet material which is 
capable of supporting thereon a positive transfer print. To effect such a 
transfer from the negative to the positive the processing fluid 12 is 
spread between the sheets 16, 18 and the sheets are kept superposed for at 
least a preselected imbibition period. The processing fluid 12 is a 
relatively viscous and easily oxidizable material. Spreading of the 
processing fluid 12 into a uniform layer is achieved by the pair of 
pressure applying rollers 20, 22 which have a predetermined gap set forth 
therebetween. As noted, the pressure applying rollers 20 and 22 facilitate 
not only superimposing of sheets 16, 18 but spreading of such fluid. It 
should be pointed out that subsequent to imbibition, the sheets 16 and 18 
are stripped by means not shown and not forming part of the present 
invention. Although the present embodiment has disclosed that the visible 
images will be formed on the positive sheet 16, it is also contemplated by 
the present invention that the visible images may be formed in the 
negative sheet 18. In this regard, the sheet 16 would serve to spread the 
processing fluid thereon. 
The fluid control system 10 is arranged to insure that the processing fluid 
12, which is of a type used in the instant photographic field, does not 
extend beyond the lateral marginal edges of the sheets as well as covers 
the exposed areas 26 on the sheet 18, between the exposed margins 28, 
being transferred. 
Essentially, the fluid control system 10 comprises a fluid distribution 
unit 30, a fluid supply arrangement 32, and a fluid monitoring assembly 
34. 
Included in the fluid distribution unit 30 is a fluid applicator 36 which 
is arranged adjacent an area at which the sheets 16, 18 become superposed 
so as to dispense a metered amount of pumped processing fluid thereto in 
the form of a puddle 14. A variety of fluid applicators can be used for 
the purposes noted. 
Referring to the fluid monitoring assembly 34, it includes a photoelectric 
assembly or apparatus 38. The photoelectric apparatus 38 is mounted by a 
clamp assembly 40 so that the apparatus can transmit a continuous focused 
beam 38a of electromagnetic radiation at a reference area 41 in a zone 42 
which is between the lateral margins of the sheets and the margins 28 of 
the exposed area 26. The photoelectric apparatus 38 is of the type which 
includes an emitter and a detector, both of which are not shown. The 
emitter transmits measured electromagnetic energy to the reference area 41 
and the detector measures a characteristic of the transmitted beam 
reflected from the area. When the transmitted beam 38a is interrupted by 
the presence of fluid 12 in the area 41, the measured characteristic of 
the reflected beam changes, which effects a generated signal 
representative of such changed condition. This signal is representative of 
the fact that the processing fluid 12 is in the reference area 41 and 
thus, too much processing fluid is in the puddle 14. As a consequence, 
there is a probability that the fluid 12 will flow off the sheet 18 and 
onto the pressure applying rollers and the like. 
The generated signal is transmitted to a known type of pump speed control 
system 44. The pump speed control system 44 is responsive to such signal 
for decrementing the speed of the motor 46 of the pump/motor assembly 48 
by a predetermined amount. By selectively decrementing the motor speed, 
the amount of processing fluid pumped by the pump 50 is accordingly 
decremented. The pump 50, in this embodiment, is a constant displacement 
type. Thus variations in viscosity will change the output. The decrease in 
the pumped amount will restore the reference area 41 to the condition it 
was in prior to the fluid interrupting the beam. When this condition 
occurs, the beam is no longer interrupted. This condition creates a signal 
which is transmitted to the pump speed control system 44. This latter 
signal is responsible for having the system 44 increment the motor speed. 
By incrementing the motor speed, by a predetermined amount, the pump 50 
correspondingly increments the output of fluid pumped. This will cause the 
edge of the puddle 14 to again extend towards the sheet's lateral edges 
until the fluid again interrupts the beam 38a. Accordingly, the control 
system 10 cyclically alternates between increasing and decreasing the 
amount of fluid distributed so that the edges thereof stay within the 
noted zone 42. 
In this embodiment, the photoelectric apparatus 38 transmits a beam of 
infrared radiation at the reference area. Use of infrared energy is 
advantageous insofar as it is non-actinic to the photosensitive sheets. 
Other forms of preferably non-actinic radiation can be used such as 
ultraviolet frequencies. Also, the present invention contemplates use of 
acoustic energy instead of the electromagnetic energy for monitoring 
purposes. Although the present embodiment describes a system which is 
arranged to keep the fluid from the marginal edges, it also contemplates a 
system wherein it is desired to have the fluid extend to the marginal 
edge. In such a system, the characteristics of the reflected beam of the 
photoelectric apparatus 38 would be changed by the absence of fluid in the 
reference area 41. The present invention also contemplates that instead of 
relying upon the characteristics of reflected energy to be indicative of 
fluid being present or absent, other sources of electromagnetic radiation 
as X-rays and gamma rays could be used. In such an arrangement, a detector 
would monitor a source of such energy for changes. The detector would be 
positioned so as to not interfere with processing operation. 
From the foregoing detailed description, it is believed the operation of 
the apparatus and the performance of method of the present invention are 
evident. 
Since certain changes may be made in the above-described method and 
apparatus without departing from the scope of the invention herein 
involved, it is intended that all matter contained in the description or 
shown in the accompanying drawings shall be interpreted as illustrative 
and not in a limiting sense.