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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 RELPLENISHER CONTROL SYSTEM Ser.
No. 321,619 filed Nov. 16, 1981; AUTOMATIC FIXED-QUANTITY/VARIABLE-TIME
ANTI-OXIDATION REPLENISHER CONTROL SYSTEM Ser. No. 323,073 filed Nov. 19,
1981; and AUTOMATIC VARIABLE-QUANTITY/VARIABLE-TIME ANTI-OXIDATION
REPLENISHER CONTROL SYSTEM Ser. No. 321,394 filed Nov. 16, 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. 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; 3,787,686 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.
SUMMARY OF THE INVENTION
The automatic control system of the present invention is an improved fixed
time, variable quantity automatic anti-oxidation replenishment control
system which eliminates the accumulated overreplenishment errors which
occurred in prior art fixed time, variable quantity systems. A time
interval is initiated and measured by a clock means. The amount of
anti-oxidation replenishment provided as a result of the exhaustion
replenishment 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 interval. If the second signal is greater than the first
signal, an amount of anti-oxidation replenishment is supplied to the
developer tank as a function of the difference between the two signals.
If, on the other hand, the first signal exceeds the second signal, no
anti-oxidation replenishment is provided and the excess is carried over to
the comparison made at the end of the subsequent interval so that
accumulated overreplenishment errors are avoided.
In one embodiment, the generation and comparison of signals in the
subsequent interval is inhibited if the difference by which the first
signal exceeds the second signal is greater than the maximum
anti-oxidation replenishment needed in the subsequent interval.
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 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 for preventing overreplenishment of
anti-oxidation fluid 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 A-O 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 fixed 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, includng 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.
An anti-oxidation replenishment control system of the present invention, as
shown in FIG. 1, uses pump 28 to transfer the needed amount of
anti-oxidation replenisher from anti-oxidation replenisher reservoir 26 to
developer tank 10. Anti-oxidation 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 is transmitted, pump 28 is stopped. Flow meter or switch 32
provides to microcomputer 20 a feedback signal for use in determining that
replenisher has been provided to developer tank 10.
The supplying of anti-oxidation replenisher to the processor using the
system of the present invention is generally as follows. AOX timer 36
initiates a fixed time interval. During this time interval, exhaustion
replenishment is provided by exhaustion replenisher 22. 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 stores the accumulated amount of anti-oxidation
replenishment supplied as a result of that exhaustion replenishment
(AOXDEV) during the current time interval. At the end of the interval, AOX
timer 36 provides a clock interrupt signal to microcomputer 20.
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 accumulated 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 goes on with its normal operating steps.
If the second signal is greater than the first, the microcomputer 20
activates anti-oxidation replenisher 24 to provide the needed amount of
anti-oxidation replenisher (AOXREPL) to developer tank 10.
The Table illustrates how microcomputer 20 determines and controls
anti-oxidation replenishment in accordance with the embodiment of the
present invention. AOXREPL is the needed quantity of anti-oxidation
replenishment fluid.
AOXNEG keeps track of excess anti-oxidation replenishment so that the
system will not be overreplenished in the subsequent time period.
Table
1. AOX timer 36 times out (e.g. 22.5 minutes)
1.a If ((AOXRATE/64)+AOXNEG) is less than zero,
(a) update AOXNEG=(AOXRATE/64)'AOXNEG
(b) reset AOX timer and exit
2 AOXREPL=(AOXRATE/64)-AOXDEV+AOXNEG
(a) if AOXREPL is less than zero,
(b) then AOXNEG=AOXREPL
(c) reset AOXDEV
(d) reset AOX timer and exit
(e) else reset AOXDEV
3 reset AOXNEG to zero
4 AOXTIME=(AOXREPL/AOXPMPRTE)+AOXMINRUN
5 If AOXTIME less than 7.5 seconds then
(a) calculate AOXMINRUN=AOXMINRUN+AOXTIME
(b) reset AOX timer and exit
6 Output AOXTIME to A-O 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) Reset AOX timer and exit
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
FIG. 2 contains a graphic representation of how anti-oxidation
replenishment is added according to the steps shown in the Table. The
horizontal axis indicates expired time. Curve 80 shows the need for
anti-oxidation replenishment due to oxidation over time. Curve 80 has a
constant slope. This is determined, in the process illustrated by the
Table, by dividing the rate of oxidation (AOXRATE) by the number of fixed
intervals in a day. Dashed curve 82 represents anti-oxidation
replenishment provided as a result of exhaustion replenishment (AOXDEV).
At any point along the time line, the vertical distance between the two
lines represents the anti-oxidation status of the system. If the curve 82
is below curve 80, the system is underreplenished. If curve 82 is above
curve 80, the system is overreplenished.
In the example shown in FIG. 2, a first fixed time interval is initialized
at time T.sub.0. The fixed time intervals end at times T.sub.1, T.sub.4,
T.sub.7, and T.sub.10. During the first time interval from T.sub.0 to
T.sub.1, no exhaustion replenishment occurs. The need for anti-oxidation
replenishment increases at a steady rate throughout the period. At time
T.sub.1, the need for anti-oxidation replenishment represented by curve 80
is compared with the AOXDEV, represented by curve 82. Brace 100 represents
this value. The amount of needed anti-oxidation replenishment (AOXREPL) is
then added at time T.sub.1.
During the second time interval from time T.sub.1 to time T.sub.4,
exhaustion replenishment occurs at times T.sub.2 and T.sub.3. Therefore,
at the end of the second interval at time T.sub.4, the difference between
the two curves is much smaller than at the end of the first interval. The
needed amount of anti-oxidation replenishment (AOXREPL) that is added at
time T.sub.4 is correspondingly smaller.
A third interval extends from time T.sub.4 to time T.sub.7. During this
interval, exhaustion replenishment occurs at times T.sub.5 and T.sub.6. At
time T.sub.5, the exhaustion replenishment curve 82 intersects the curve
80 and extends above it. For the period from time T.sub.5 to time T.sub.6,
the system is slightly overreplenished as to anti-oxidation. At time
T.sub.6, the curves intersect. When exhaustion replenishment occurs at
time T.sub.6, the system is again overreplenished. When the interval ends
at time T.sub.7, the system is still overreplenished. Therefore, no
anti-oxidation replenishment is provided and the parameters are not
reinitialized. Computation continues through the next period, which
extends from T.sub.7 to T.sub.10. At time T.sub.8, the curves again
intersect and the system is slightly underreplenished when exhaustion
replenishment occurs again at time T.sub.9. At time T.sub.10 at the end of
the fourth interval, the system is underreplenished. At this point,
anti-oxidation replenishment (AOXREPL) occurs. The parameters are
reinitialized and the intervals start anew.
A variable quantity system is best used in a system where precision in
replenishment is required. A variable quantity system provides exact
measurement. A control system constructed according to the present
invention eliminates the problem of accumulated anti-oxidation
overreplenishment errors to which the prior systems were subject. By
considering in a subsequent interval the excess anti-oxidation
replenishment provided by exhaustion replenishment in a previous interval,
the accumulated overreplenishment errors are prevented.
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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