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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a replenisher control system for use in
processors of photosensitive material.
2. Description of the Prior Art
Automatic photographic film and paper processors transport sheets or webs
of photographic film or paper through a sequence of processor tanks in
which the photosensitive material is developed, fixed, and washed, and
then transports the material through a dryer. It is well known that
photographic processors require replenishment of the processing fluids to
compensate for changes in the chemical activity of the fluids.
First, it has been recognized that replenishment is necessary to replace
constituents used as photosensitive film or paper is developed in the
processor. This replenishment is "use related" or "exhaustion" chemical
replenishment. Both developer and fix solutions require exhaustion
replenishment.
Second, chemical activity of the developer solution due to aerial oxidation
occurs with the passage of time regardless of whether film or paper is
being processed. Some replenishment of an "anti-oxidation" (A-O)
replenishment solution which counteracts this deterioration.
Replenishment systems were originally manually operated. The operator would
visually inspect the processed film or paper and manually operate a
replenisher system as he deemed necessary. The accuracy of the manual
replenisher systems was obviously dependent upon the skill and experience
of the operator.
Various automatic replenishment systems have been developed for providing
use-related replenishment. Examples of these automatic replenishment
systems include U.S. Pat. Nos. 3,472,143 by Hixon et al; 3,529,529 by
Schumacher; 3,554,109 by Street et al; 3,559,555 by Street; 3,561,344 by
Frutiger et al; 3,696,728 by Hope; 3,752,052 by Hope et al; 3,787,689 by
Fidelman; 3,927,417 by Kinoshita et al; 3,990,088 by Takita; 4,057,818 by
Gaskell et al; 4,104,670 by Charnley et al; 4,119,952 by Takahashi et al;
4,128,325 by Melander et al; and 4,134,663 by Laar et al. Examples of
prior art replenisher controls for providing both exhaustion and
anti-oxidation replenishment are shown in U.S. Pat. Nos. 3,822,723 by
Crowell et al and 4,174,169 by Melander et al.
In the past, test strips or control strips of photosensitive material have
been processed and then evaluated for determining whether the processor is
yielding processed material having the desired densities. Patents showing
automatic evaluation of test strips include U.S. Pat. Nos. 3,623,418 by
Ost; 3,636,851 by Furst; and 3,995,959 by Shaber.
The Ost Patent 3,623,418 describes a system in which a test strip of
photographic film is transported through a developer sample chamber, where
it is developed using a sample of developer fluid from the main developer
tank. The developed test strip then passes between a lamp and a
densitometer head, which senses the intensity of light transmitted through
the test strip. The resistance of the densitometer is connected in a
bridge circuit which is used to control replenishment.
The Furst U.S. Pat. No. 3,636,851 shows a film processor which includes a
sensitometer for recording test information on a test prior to the test
film entering the processor tanks, and a densitometer at the output end of
the processor for measuring density of the processed test film. The Furst
patent suggests the possibility of supplying the densiometric data in
digital form to a process controller to control the entire manufacturing
operation.
The Shaber U.S. Pat. No. 3,995,959 shows a processor in which a test strip
includes areas of unexposed (base fog) area, light (medium density) area,
and dark (high density) area. Densitometer readings are made of the
processed test film and signals are generated indicating whether the base
fog area is acceptable or too dark; whether the dark area is acceptable or
too light; and whether the medium area is acceptable, too light, or too
dark. Based upon these signals, light emitting diodes are lit to indicate
the status of the film processor. The light emitting diodes indicate the
following conditions: acceptable, developer underreplenished, developer
temperature too low, developer overreplenished, developer temperature too
high, and developer contaminated.
SUMMARY OF THE INVENTION
The automatic replenisher control system of the present invention makes
supplemental adjustments to developer and anti-oxidation replenishment in
a photographic processor as a function of measured density values from
control strips which are periodically processed by the photographic
processor. The control system includes means for storing density aim point
values which indicate desired sensitivity and screen range values of the
control strips.
If the measured sensitivity of a control strip is outside a desired
sensitivity range, the control system makes a small bulk addition of
exhaustion developer replenishment or inhibits developer exhaustion
replenishment for a predetermined time interval, depending on whether the
measured sensitivity is below or above the desired range. The control
system requests another control strip at the end of a predetermined
interval, and compares measured sensitivity to the desired sensitivity
range for the new control strip. If the measured sensitivity continues to
deviate from the desired sensitivity range, the control system adjusts the
developer exhaustion replenishment rate and requests another control strip
at the end of a predetermined interval. This process of bulk adjustments
and replenishment rate adjustments continues until the measured
sensitivity falls within the desired sensitivity range.
Similar bulk adjustments and adjustments of anti-oxidation replenishment
rate are performed based upon the measured screen range from the control
strips. The control system first attempts to bring the measured screen
range value into the desired range by bulk adjustment, and requests
another control strip after a predetermined interval. If the measured
contrast continues to deviate from the desired range, adjustment of the
anti-oxidation replenishment rate is made. The process continues until the
measured screen range of a control strip falls within the desired contrast
range.
The automatic replenisher control system of the present invention,
therefore, distinguishes between long term deviations in developer
chemistry and short term deviations in developer chemistry (which can
occur due to the processing of only one or just a few sheets of material
having a substantially different density image from normal). Bulk
adjustments provided by a bulk addition of replenisher or inhibiting
replenishment for a predetermined time interval often will correct a short
term deviation in developer chemistry, without the need for disturbing the
developer exhaustion replenishment rate or the anti-oxidation
replenishment rate. If, however, long term deviations occur, these
indicate that the exhaustion replenishment rates are no longer correct,
and the control system of the present invention makes adjustments to the
replenishment rates until the developer chemistry again yields the desired
sensitivity and screen range in the control strips.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a preferred embodiment of the
automatic replenishment control system of the present invention.
FIG. 2 is a block diagram illustrating another preferred embodiment of the
automatic replenishment control system of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As shown in FIG. 1, the automatic replenishment control system of the
present invention controls replenishment of processor fluids in a
photographic processor. In the system shown in FIG. 1, the processor
includes developer tank 10, fix tank 12, wash tank 14, and dryer 16. Film
transport drive 18 transports the strip or web of photosensitive material
(either film or paper) through tanks 10, 12, 14 and dryer 16.
Microcomputer 20 controls operation of film transport 18 and of the
automatic replenishment of fluids to tanks 10, 12 and 14.
The auto-replenishment system shown in FIG. 1 includes developer
replenisher 21a and anti-oxidation replenisher 21b for providing
exhaustion and anti-oxidation replenishment, respectively, to developer
tank 10. In addition, the system includes fix replenisher 21c for
providing fix replenishment to fix tank 12, and wash replenisher 21d for
providing wash replenishment to wash tank 14.
Developer replenisher 21a includes exhaustion replenishment reservoir 22,
pump 24, pump relay 26, and flow meter or switch 28. Exhaustion
replenishment for developer tank 10 is supplied from exhaustion
replenishment reservoir 22 by means of pump 24. Microcomputer 20 controls
operation of pump 24 through pump relay 26. Flow meter or switch 28
monitors the exhaustion replenishment fluid actually pumped by pump 24 to
developer tank 10, and provides a feedback signal to microcomputer 20.
Anti-oxidation replenisher 21b includes A-O replenisher reservoir 30, pump
32, pump relay 34, and flow meter or switch 36. Anti-oxidation
replenishment is supplied from A-O replenisher reservoir 30 to developer
tank 10 by pump 32. Microcomputer 20 controls operation of pump 32 by
means of relay 34. Flow meter or switch 36 monitors flow of A-O
replenishment to developer tank 10 and provides a feedback signal to
microcomputer 20.
Fix replenisher 21c includes fix replenisher reservoir 38, pump 40, pump
relay 42, and flow meter or switch 44. Fix replenishment is supplied to
fix tank 12 from fix replenisher reservoir 38 by pump 40, which is
controlled by microcomputer 20 through relay 42. Flow meter of switch 44
monitors flow of replenishment fluid to fix tank 12, and supplies a
feedback signal to microcomputer 20.
Wash replenisher 21d, which includes wash reservoir 46, pump 48, pump relay
50, and flow meter or switch 52, provides replenishment of wash fluid
(typically water) in wash tank 14. The wash fluid is supplied from wash
replenishment reservoir 46, and is pumped to wash tank 14 by pump 48.
Microcomputer 20 controls pump 48 through relay 50, and monitors the flow
of wash replenishment to tank 14 by means of flow meter or switch 52.
Microcomputer 20 utilizes developer counter 56, A-O counter 57, fix counter
58, and wash counter 59 as timers to control replenishment. When, for
example, exhaustion replenishment is required, microcomputer 20 loads a
numerical value (DEVTIME) into developer counter 56, which then begins
counting. Microcomputer 20 energizes relay 26, which actuates pump 24.
When developer counter 56 reaches a predetermined value (such as zero), it
provides an interrupt signal to microcomputer 20, which de-energizes relay
26. The numerical value (DEVTIME), therefore, determines the total amount
of exhaustion developer replenisher pumped into tank 10.
Counters 57, 58 and 59 are operated in a similar manner. The numerical
values loaded into counters 57, 58 and 59 are hereafter referred to as
AOXTIME, FIXTIME and WASHTIME, respectively.
AOX time 60 is a free running timer which provides an interrupt signal to
microcomputer 20 on a periodic basis to initiate A-O replenishment. In one
preferred embodiment, AOX timer 60 provides the interrupt signal every
22.5 minutes.
Microcomputer 20 also receives signals from film width sensors 62 and
density scanner 64. Film width sensors 62 are positioned at the input
throat of the processor, and provide signals indicating the width of the
strip of photosensitive material as it is fed into the processor. Since
microcomputer 20 also controls film transport 18, and receives feedback
signals from film transport 18, the width signals from film width sensors
62 and the feedback signals from film transport 18 provide an indication
of the area of photosensitive material being processed.
Density scanner 64 senses density of the processed photosenstive material.
The signals from density scanner 64 provide an indication of the
integrated density of the processed photosensitive material. The
integrated density, together with the area of material processed, provides
an indication of the amount of processor fluids used in processing that
material.
Microcomputer 20 also receives signals from control panel 66, which
includes function switches 68, keyboard 70, and display 72. Function
switches 68 select certain functions and operating modes of the processor.
Keyboard 70 permits the operator to enter numerical information, and other
control signals used by microcomputer 20 in controlling operation of the
processor, including replenishment. Display 72 displays messages or
numerical values in response to control signals from microcomputer 20.
In the preferred embodiments of the invention, the replenishment control
system is usable in a processor capable of processing both film and paper.
In one embodiment, in which density scanner 64 operated on a basis of
light transmission through the photosensitive material, density scanner 64
is unable to determine the densities of images on photographic paper.
Therefore, the approximate density of images on the paper are provided by
function switches 72. For example, function switches 72 permit the
operator to select an approximate density of twenty-five percent, fifty
percent, or seventy-five percent for the images on the paper. When one of
these switches is selected, microcomputer 20 controls replenishment on the
basis of these approximate density values, rather than signals from
density scanner 64.
Also shown in FIG. 1 is real time clock 74, which maintains the time of
day. Real time clock 74 preferably is provided with battery backup power
50 so that it continues to operate even when power to the processor is
turned off.
In a preferred embodiment of the present invention, microcomputer 20 stores
set values for each of a plurality of photosensitive materials that may be
processed in the processor. Each group of set values includes pump rates
for pump 24 (DEVPMRATE), pump 32 (AOXPMPRTE), pump 40 (FIXPMPRTE) and pump
48 (WASHPMPRTE); desired replenishment rates of exhaustion developer
(DEVRATE) A-O replenishment (AOXRATE), fix replenishment (FIXRTE), and
wash replenishment (WASHRATE); and density aim point values for control
strips which are processed in the processor. These density aim points
preferably include a low density value and a high density value. The low
density set point value indicates "sensitivity" and the difference between
the low density value and the high density value provides an indication of
"screen range".
In addition, microcomputer 20 preferably stores speed set point values for
both a process speed and a creep speed. These set point values are used in
controlling film transport 18
When operation is commenced, the operator selects one of the groups of set
values which corresponds to the pa | | |
