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CROSS REFERENCE TO PATENTS AND COPENDING APPLICATIONS
Reference is hereby made to my patents entitled AUTOMATIC REPLENISHER
CONTROL SYSTEM, U.S. Pat. No. 4,293,211, issued Oct. 6, 1981; AUTOMATIC
ANTI-OXIDATION REPLENISHER CONTROL, U.S. Pat. No. 4,295,792, issued Oct.
20, 1981; and the following copending applications: AUTOMATIC
FIXED-QUANTITY/FIXED-TIME ANTI-OXIDATION REPLENISHER CONTROL SYSTEM, Ser.
No. 321,619 filed Nov. 16, 1981; AUTOMATIC VARIABLE-QUANTITY/FIXED-TIME
ANTI-OXIDATION REPLENISHER CONTROL SYSTEM, Ser. No. 321,392 filed Nov. 16,
1981; and AUTOMATIC FIXED-QUANTITY/VARIABLE-TIME ANTI-OXIDATION
REPLENISHER CONTROL SYSTEM, Ser. No. 323,073 filed Nov. 19, 1981. All of
these applications are assigned to the assignee of the present
application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic anti-oxidation 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 transport 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. Replenishment systems provide additional 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
replenishment system as he deemed necessary. The accuracy of the manual
replenishment 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. 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; 3,787,686 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. Re. 30,123 by
Crowell et al and 4,174,169 by Melander et al. In particular, these
patents show systems which are usable to control anti-oxidation
replenishment when a type of anti-oxidation replenishment known as
"blender chemistry" is used. Blender chemistry is based upon a "minimum
daily requirement" of anti-oxidation replenishment. This minimum daily
requirement is dependent upon the amount of aerial oxidation which occurs
in the developer tank, which in turn is dependent upon the open surface
area of the tank, the operating temperature of the developer solution, and
a number of other factors. With blender chemistry, some anti-oxidation
replenishment is provided each time that exhaustion replenishment occurs.
The more exhaustion replenishment provided, the less separate
anti-oxidation replenishment is required.
Crowell discloses a variable quantity, fixed time anti-oxidation
replenishment control in which a variable amount of anti-oxidation
replenishment needed due to aging is determined at fixed time intervals
based upon the replenishment provided by use or exhaustion replenishment
during the time interval. At fixed time intervals, a needed amount of
anti-oxidation replenishment is added, which varies from zero up to a
predetermined maximum amount. The more exhaustion replenishment provided
during the time interval, the less anti-oxidation replenishment is
required. The apparatus in Crowell does not consider, however, the
situation where more anti-oxidation replenishment than is needed is
provided by the exhaustion replenishment. Thus overage can lead to an
accumulated error in the Crowell system. Overreplenishment of
anti-oxidation fluid will produce incorrect processing results, just as
will underreplenishment. There is no recognition in Crowell that this
error accumulation can occur, or of any way to resolve it. In addition,
the system of Crowell et al is limited by its use of analog electronics
and electromechanical cams, which make the system difficult to calibrate
and limit the number of control options available to the user.
Melander et al discloses a fixed quantity, variable time anti-oxidation
system based on a counter which is set to a predetermined value and then
counted down over time to measure oxidation of processor fluid. When the
counter reaches zero, a fixed amount of anti-oxidation replenisher is
added. The counter is counted up to reflect anti-oxidation replenishment
provided as a result of exhaustion replenishment.
SUMMARY OF THE INVENTION
The automatic control system of the present invention is a variable
quantity, variable time anti-oxidation replenishment control system which
adds a variable amount of anti-oxidation replenishment fluid to the
developer tank at variable time intervals which vary as a function of
exhaustion replenishment provided. The time at which this variable amount
is added is determined by initiating a first fixed time interval, which is
measured by a clock means. The amount of anti-oxidation replenishment
provided as a result of the exhaustion replenishment during the time
interval is used to provide a first replenishment signal. A stored
anti-oxidation replenishment rate and the measured time are used to
provide a second replenishment signal indicative of how much
anti-oxidation replenishment is needed. The two signals are compared at
the end of the time interval. If the second signal is equal to or greater
than the first signal, an amount of anti-oxidation replenishment
represented by the difference is supplied to the developer tank. If the
first signal exceeds the second signal, the length of a subsequent time
interval is increased as a function of the difference between the first
and second signals. By considering and compensating for the excess
anti-oxidation replenishment provided by exhaustion replenishment, the
automatic control system of the present invention eliminates the
overreplenishment of anti-oxidation fluid which occurs in prior art
systems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a processor including a preferred
embodiment of the automatic anti-oxidation replenishment control system of
the present invention.
FIG. 2 is a graph illustrating the operation of the control system of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the system shown in the FIG. 1, a photographic processor includes
developer tank 10, fix tank 12, wash tank 14, and dryer 16. Film transport
drive 18 transports a 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 automatic replenishment system shown in FIG. 1 includes developer
replenisher 22 and anti-oxidation replenisher 24 for providing exhaustion
and anti-oxidation replenishment, respectively, to developer tank 10.
Microcomputer 20 controls operation of developer replenisher 22 and
receives a feedback signal indicating operation of developer replenisher
22. Although in a typical processor fix and wash replenishment also are
provided, these functions are not a part of the present invention, and
therefore are not shown or discussed herein.
Anti-oxidation replenisher 24 includes anti-oxidation (A-O) replenisher
reservoir 26, pump 28, pump relay 30, and flow meter or switch 32.
Anti-oxidation replenishment is supplied from A-O replenisher reservoir 26
to developer tank 10 by pump 28 by means of relay 30 which is controlled
by microcomputer 20. Flow meter or switch 32 monitors flow of A-O
replenishment to developer tank 10 and provides a feedback signal to
microcomputer 20.
Microcomputer 20 utilizes A-O counter 34 as a timer to control
anti-oxidation replenishment. When anti-oxidation replenishment is
required, microcomputer 20 loads a numerical value (AOXTIME) into A-O
counter 34, which then begins counting. Microcomputer 20 energizes relay
30, which activates pump 28. When developer counter 34 reaches a
predetermined value (such as zero), it provides an interrupt signal to
microcomputer 20, which deenergizes relay 30. The numerical value
(AOXTIME), therefore, determines the total amount of anti-oxidation
replenisher pumped into tank 10.
AOX timer 36 is a free running resettable timer which initiates and records
a variable time interval. As described later, this time interval is used
by microcomputer 20 in the control of anti-oxidation replenishment.
Microcomputer 20 receives signals from film width sensors 38 and density
scanner 40. Film width sensors 38 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
38 and the feedback signals from film transport 18 provide an indication
of the area of photosensitive material being processed.
Density scanner 40 senses density of the processed photosensitive material.
The signals from density scanner 40 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 or exhausted in
processing that material.
Microcomputer 20 also receives signals from control panel 42, which
includes function switches 44, keyboard 46, and display 48. Function
switches 44 select certain functions and operating modes of the processor.
Keyboard 46 permits the operator to enter numerical information, and other
control signals used by microcomputer 20 in controlling operation of the
processor, including the replenishment function. Display 48 displays
messages or numerical values in response to control signals from
microcomputer 20.
Microcomputer 20 preferably stores set values for each of a plurality of
photosensitive materials that may be processed in the processor. Each
group of set values includes a pump rate for pump 28 (AOXPMPRTE), and the
desired replenishment rate of anti-oxidation replenishment (AOXRT).
When operation is commenced, the operator selects (through control panel
42) one of the groups of set values which corresponds to the particular
photosensitive material being processed. As the leading edge of each strip
of photosensitive material is fed into the processor, film width sensors
38 sense the presence of the strip, and provide a signal indicative of the
width of the strip being fed into the processor. Width sensors 38 continue
to provide the signal indicative of the width of the strip until the
trailing edge of the strip passes sensors 38. The length of time between
the leading and trailing edges of the material passing sensors 38, and the
transport speed of the material (which is controlled by microcomputer 20
through film transport 18) provide an indication of the length of the
strip. The width and length information for each strip is stored until the
strip has been transported through the processor and reaches density
scanner 40. The area of the strip and the integrated density of the strip
(which is provided by the signals from density scanner 40), provide an
indication of the amount of developer which has been exhausted in
processing that particular strip.
As discussed previously, the present invention relates to the type of an
anti-oxidation replenishment known as "blender chemistry". Blender
chemistry is based upon a "minimum daily requirement" of anti-oxidation
replenishment. This minimum daily requirement is dependent upon the amount
of aerial oxidation which occurs in developer tank 10, which in turn is
dependent upon the open surface area of tank 10, the operating temperature
of the developer solution, and a number of other factors. With blender
chemistry, some anti-oxidation replenishment is provided each time that
exhaustion replenishment occurs. The more exhaustion replenishment
provided, the less separate anti-oxidation replenishment is required.
The anti-oxidation replenishment control system shown in FIG. 1 uses pump
28 to transfer the necessary amount of anti-oxidation replenisher from
anti-oxidation replenisher reservoir 26 to developer tank 10. A-O counter
34 is used to measure the amount of time that pump 28 will run, so that
the correct amount is transferred to developer tank 10. When microcomputer
20 activates relay 30 to start pump 28, A-O counter 34 begins timing. When
the proper amount of anti-oxidation replenishment has been transmitted,
pump 28 is stopped. Flow meter or switch 32 provides to microcomputer 20 a
feedback signal indicating that anti-oxidation replenisher has been
provided to developer tank 10.
The addition of anti-oxidation replenisher is generally as follows. When
operation is first commenced, AOX timer 36, under the control of
microcomputer 20, initiates a first standard minimum time interval. During
this time interval, exhaustion replenishment is provided, as needed, by
exhaustion replenisher 22 under the control of microcomputer 20. This is
done, as discussed above, as a function of the use of the developer fluid
in tank 10. The use is indicated by the signals from film width sensors
38, density scanner 40, and film transport 18. Microcomputer 20 then
determines and starts to accumulate a first signal representing the amount
of anti-oxidation replenishment supplied as a result of that exhaustion
replenishment during the time interval (AOXDEV).
At the end of the first time interval, microcomputer 20 uses a stored
anti-oxidation replenishment rate (AOXRT) and the time expired in the
interval (AOXTM), as measured by AOX timer 36, to determine a second
signal (AOXRT.times.AOXTM) which indicates the amount of anti-oxidation
replenishment required in the current time interval. Microcomputer 20 then
compares the first signal (AOXDEV) indicating the amount of anti-oxidation
replenishment supplied in the interval as a result of the exhaustion
replenishment with the second signal (AOXRT.times.AOXTM) indicating
anti-oxidation replenishment required at the current time in the interval.
If the first signal is greater than the second signal, no anti-oxidation
replenishment is required and the microcomputer 20 extends the next time
interval to a length which is greater than the standard minimum interval
as a function of the amount by which the first signal exceeds the second
signal. Microcomputer 20 then initiates the next time interval and goes on
with its normal operating steps.
If, on the other hand, the second signal is greater than the first signal,
the microcomputer 20 activates anti-oxidation replenisher 24 to provide
the needed amount of anti-oxidation replenisher to developer tank 10. This
needed amount is based upon the amount by which the second signal exceeds
the first signal. The next time interval is the initiated and is given a
length equal to the standard minimum interval.
The following table illustrates how microcomputer 20 determines and
controls anti-oxidation replenishment in accordance with the embodiment of
the present invention. AOXREPL is a variable quantity of anti-oxidation
replenishment fluid. AOXPER is a value in seconds which represents the
period until the next calculation of anti-oxidation replenishment. In
other words, AOXPER is the value of AOXTM at the end of the time interval.
AOXPER is initially set to the standard minimum interval, for example,
22.5 minutes. AOXRT is the amount of replenishment needed per second.
TABLE
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1 AOX timer 36 reaches AOXPER
2 AOXREPL = (AOXRT .times. AOXPER) - AOXDEV
3 if AOXREPL is less than zero
(a) AOXNEG = AOXREPL
(b) reset AOXDEV
(c) complement AOXNEG
(d) AOXPER = (AOXNEG / AOXRATE) +
(22.5 min. .times. 60)
(e) go to 1
(f) else reset AOXDEV
4 AOXTIME = AOXREPL / AOXPMPRTE +
AOXMINRUN
5 If AOXTIME less than 7.5 seconds then
(a) Calculate AOXMINRUN + AOXMINRUN =
AOXTIME
(b) Return to 1.1
6 Output AOXTIME to counter 34
7 Trigger pulse sent to counter 34 and
(a) Replenish flag (AOX) set
8 Counter 34 begins decrementing and
(a) Anti-ox replenishment pump 28 runs
(b) When counter 34 times out, go to 11
9 If flow switch 32 does not activate and/or
Anti-ox replenishment pump relay 30 does not
energize then ERROR
10 If pump enable is turned off while counter 34
is running then
(a) Wait 5 seconds
(b) If change then resume 8
Else
(1) Read value remaining in counter 34 to AOXREM
(2) Clear counter 34
(3) Replenish flag (AOX) reset
(4) Return to 1
11 Counter 34 times out and
(a) Interrupt request generated
12 If interrupt request not acknowledged then
wait;
Else
13 If flow switch 32 remains activated and/or pump
relay 30 remains energized then ERROR;
Else
14 Reset replenish (AOX) flag and AOX not complete
flag and clear AOXMINRUN
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FIG. 2 is a graphic representation of the process described in the Table.
The horizontal axis represents expired time, starting at initialization
point T.sub.0. Slanted curve 80 shows the need for anti-oxidation
replenishment, which increases at a steady rate as a function of the
stored anti-oxidation replenishment rate (AOXRT) and expired time in the
interval (AOXTM). Dashed curve 82 shows anti-oxidation replenishment
provided by exhaustion replenishment (AOXDEV). The vertical distance
between curves 80 and 82 (AOXNED) equals the difference between needed
anti-oxidation replenishment due to time (AOXRT.times.AOXTM) and AOXDEV.
A first time interval (with a length equal to the standard minimum
interval) is initiated at T.sub.0 and extends to time T.sub.1. During this
first interval, no exhaustion replenishment occurs. At the end of the
interval, the difference between curves 80 and 82 shows the amount of
needed anti-oxidation replenishment (AOXNED=(AOXRT.times.AOXTM)-AOXDEV).
This amount is added at time T.sub.1. At this point, a second time
interval of the same length is initiated, and extends from time T.sub.1 to
time T.sub.4. During this second interval, exhaustion replenishment occurs
at times T.sub.2 and T.sub.3, which is shown by the vertical portions of
the curve 82. At the end of the second fixed time interval, the difference
(AOXNED) which is provided is smaller than the replenishment at T.sub.1,
since exhaustion replenishment in the second interval provided some
anti-oxidation replenishment.
Once again at T.sub.4, a third time interval equal to the standard minimum
interval is initiated. This third time interval extends from time T.sub.4
to time T.sub.7. During this third time interval, exhaustion replenishment
occurs at times T.sub.5 and T.sub.6. The replenishment at time T.sub.6
moves curve 82 above curve 80. Therefore from time T.sub.6 to time T.sub.8
(in the fourth interval), the system is slightly overreplenished; i.e.,
AOXNED is less than zero. When the third interval ends at time T.sub.7,
curve 82 is above curve 80. Because the system is overreplenished, no
anti-oxidation replenishment is needed and none is provided. The counters
are not reset and calculations continue.
A fourth time interval is initiated at time T.sub.7. Because the system is
overreplenished, however, the fourth time interval is extended by
microcomputer 20. Normally the fourth time interval would extend from time
T.sub.7 to time T.sub.11. Because the system is overreplenished, the
interval is extended to time T.sub.12. The time indicated between T.sub.11
and T.sub.12 represents the time needed to use up the excess replenishment
indicated at T.sub.7. This extension of the time interval reduces the
frequency of computations by microcomputer 20. During the fourth interval,
exhaustion replenishment occurs at times T9 and T.sub.11. When the
interval ends at time T.sub.12, an amount of replenishment (AOXNED) is
needed and added. The microcomputer 20 then reinitializes its counters and
initiates a new interval equal in length to the standard minimum interval.
The variable quantity anti-oxidation replenishment system of the present
invention is particularly advantageous where precise accuracy is needed.
By varying the quantity, the system prevents significant underage or
overage in anti-oxidation replenisher fluid. The system of the present
invention also takes advantage of the precise computational and control
capabilities of a microcomputer 20. It provides control of anti-oxidation
replenishment which is far more accurate and flexible than the prior art
system shown in the Crowell patent, in that it utilizes digital
electronics rather than analog electro-mechanical devices, and it avoids
the accumulated overreplenishment error which can occur with the Crowell
system.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize that
changes may be made in form and detail without departing from the spirit
and scope of the invention.
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