U.S. patent number 3,559,555 [Application Number 04/734,297] was granted by the patent office on 1971-02-02 for image monitoring and control system.
This patent grant is currently assigned to Logetronics Inc.. Invention is credited to John N. Street.
United States Patent |
3,559,555 |
Street |
February 2, 1971 |
IMAGE MONITORING AND CONTROL SYSTEM
Abstract
A system is provided for automatically controlling chemical
replenishment in a chemical-containing automatic film processor. As
sheets of varying density image bearing material are transported
through the processor, the varying density images in each of said
sheets are optically monitored throughout substantially the entire
width and length of each sheet. Information is stored relating to
the aggregate image density in the monitored sheets; and a
preselected quantity of replenishment chemical is supplied to the
processor when the aggregate image density reaches a predetermined
value.
Inventors: |
Street; John N. (Alexandria,
VA) |
Assignee: |
Logetronics Inc. (Springfield,
VA)
|
Family
ID: |
24951098 |
Appl.
No.: |
04/734,297 |
Filed: |
June 4, 1968 |
Current U.S.
Class: |
396/569; 396/570;
385/120 |
Current CPC
Class: |
G03D
3/065 (20130101) |
Current International
Class: |
G03D
3/06 (20060101); G03d 003/00 (); G03d 003/06 () |
Field of
Search: |
;95/89,94 ;350/96 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Horan; John M.
Assistant Examiner: Greiner; Robert P.
Claims
I claim:
1. A film processor replenishment system comprising a film
processor, means for transporting a plurality of sheets of varying
image density bearing material through said processor for
development therein, the developed sheets having different image
densities at different areal portions thereof, sensor means
adjacent said processor for monitoring the incremental density
throughout substantially the entire length and width of each of
said plurality of sheets of image bearing material, accumulator
means coupled to said sensor means for producing an information
signal related to the aggregate incremental image density of each
said sheet and to the aggregate image densities of a plurality of
such varying image density sheets, a source of replenishment
chemical for said film processor, and control means responsive to
said information signal for selectively controlling the feeding of
replenishment chemical from said source to said processor when said
aggregate image density reaches a preselected value.
2. The system of claim 1 wherein said sensor means includes means
for optically scanning substantially the entire area of each of
said developed sheets at a scanning rate related to the speed of
transport of said sheet through said processor.
3. The system of claim 1 wherein said control means includes a
valve between said source and said processor, and timer means for
selectively opening said valve for a predetermined time
interval.
4. The system of claim 3 including flow control means for metering
replenishment chemical from said source at a predetermined flow
rate when said valve is open.
5. The system of claim 1 wherein said accumulator means is
operative to produce a signal which changes in magnitude, and level
detector means responsive to the magnitude of said signal.
6. The system of claim 1 wherein said processor includes a
container having development chemical therein, said sensor being
located at a position downstream of said development chemical
container to monitor the image density in each of said sheets after
said sheet has been developed.
7. The system of claim 1 wherein said processor includes a
development tank, a fixer tank, a wash tank, and drier means, said
processor including transport means for transporting each of said
sheets through said tanks in succession and in the order named to
said drier means, said sensor means being located adjacent the
input end of said drier means.
8. A film processor replenishment system comprising a film
processor having means for automatically transporting a plurality
of sheets of image-bearing material through said processor for
development therein, sensor means adjacent said processor for
monitoring the image density throughout substantially the entire
area of each of said plurality of sheets of image-bearing material,
said sensor means including a fiber optics array extending
transverse to the path of travel of each such sheet through said
processor and further including means coupled to said array for
optically scanning each of said sheets at a rate related to the
speed of transport of said sheet through said processor,
accumulator means coupled to said sensor means for producing an
information signal related to the image density of each said sheet
and to the aggregate densities of a plurality of such sheets, a
source of replenishment chemical for said film processor, and
control means responsive to said information signal for selectively
controlling the feeding of replenishment chemical from said source
to said processor.
9. The system of claim 8 wherein individual fibers in said array
are distributed along a line extending transverse to the path of
travel of each sheet through said processor.
10. The system of claim 8 wherein said sensor means includes light
distributor means disposed adjacent the path of travel of said
sheets through said processor, said fiber optics array comprising
plural bundles of optical fibers connected respectively to spaced
portions of said light distributor means.
11. A film processor replenishment system comprising a film
processor, sensor means adjacent said processor for monitoring the
image density throughout substantially the entire area of each of a
plurality of sheets of image-bearing material, said sensor means
including means for scanning each of said sheets along a plurality
of linear scan paths, accumulator means coupled to said sensor
means for producing an information signal related to the image
density of each said sheet and to the aggregate densities of a
plurality of such sheets, said accumulator means including first
integrator means for storing a signal related to the aggregate
image density monitored during each of said linear scans and
further integrator means coupled to said first integrator means for
storing a signal related to the aggregate image density monitored
during a plurality of said linear scans, a source of replenishment
chemical for said film processor, and control means responsive to
said information signal for selectively controlling the feeding of
replenishment chemical from said source to said processor.
12. The system of claim 11 wherein said further integrator means
includes a storage capacitor.
13. The system of claim 11 wherein said further integrator means
includes an electromechanical stepping switch.
14. The method of controlling chemical replenishment in a chemical
containing automatic processor of image-bearing materials
comprising the steps of passing sheets of varying image density
bearing material through said processor for processing by chemicals
in said processor, optically monitoring the varying density images
in each of said sheets throughout substantially the entire width
and length of each sheet after each of said sheets has been
processed by said chemicals, storing information related to the
aggregate image density in said monitored sheets, and supplying a
preselected quantity of a replenishment chemical to said processor
when said aggregate image density reaches a predetermined value.
Description
BACKGROUND OF THE INVENTION
Various forms of automatic processors adapted to develop, fix, wash
and dry sheets of photosensitive material are already known to
those skilled in the art. In such processors, a sheet of
photosensitive material to be processed is fed in sequence from one
processor tank to the next; and the developed, fixed and washed
material is then automatically passed through a drier and
collected. In the normal operation of such processors, the
chemicals employed for processing the photosensitive material tend
to become depleted as sheets of such material are processed; and
unless some form of chemical replenishment is effected during
continued operation of the processor, there will be severe
degradation in the image quality of the films being developed. It
is, accordingly, customary to include some form of controllable
replenishment facility in automatic film processors, intended to
maintain chemical concentrations in the processor tanks at desired
levels, or within desired limits.
One form of replenishment system already known to those skilled in
the art constitutes a manually operable control adapted to open
solenoid controlled valves for a desired time interval. The
solenoid controlled valves are positioned between tanks of
replenishing chemicals and the processor developer and fixer tanks,
so that various amounts of replenishment chemicals can be added to
the processor tanks in accordance with visual estimates made by the
operator of the processor equipment. These visual estimates are, in
turn, normally made by the operator of the equipment on the basis
of the film size and degree of exposure of the particular sheet of
film to be processed; and the operator of the equipment normally
"dials in" or otherwise manually controls the amount of
replenishment chemical which he estimates to be needed for each
sheet of material processed.
The accuracy of manual replenishment controls of the types
described above is less than may be desirable since it depends in
large part upon a rough visual estimate made by the operator of the
equipment. Any errors in such an estimate may be cumulative over a
period of time; and, as a result, no one can be sure of the
chemical activity of the processor solutions after an extended
period of operation and manual replenishment. In order to confirm
the state of the processor solutions after a period of time, it is
accordingly also customary to pass so-called process control strips
having precisely exposed latent images thereon, through the
processor. After processing, these strips are analyzed
densitometrically and the readings obtained are used to maintain a
process control chart which will show trends and changes in
processor performance. Such charts normally include plots of two
types of information, i.e., the "developer speed" which is
indicative of the maximum density to which an image having a given
exposure will develop, and the "gradient" which is indicative of
the developed image contrast. The objective of the process control
chart is to monitor trends in these two factors, so that by
controlling replenishment, an attempt can be made to keep both
factors within acceptable limits.
When process control strips are employed, the accuracy of
replenishment is related to the frequency with which such strips
are run, the skill of the operator in preparing and interpreting
the process control chart, and his ability to control replenishment
to counteract observed trends. Obviously, if process control strips
are run only at relatively widely spaced time intervals, it is
difficult to know what the trends are. Therefore, assuming that the
operator is sufficiently skilled to compensate for observed trends,
an ideal situation would require that a process control strip be
run with practically every sheet of film being developed. This,
however, is so costly and time consuming as to be economically
impractical. A compromise is, therefore, often struck and process
control strips are run every hour or the like. On the basis of the
information gained by obtaining and plotting data from such process
control strips, the operator of the manual replenishment system
tries, within the limits of his expertize, either to increase or
decrease (or he eliminates) replenishment in an effort to
counteract observed trends.
Manual replenishment systems of the types described above are
capable of keeping the processor within desired control limits over
a period of time. The very nature of this type of replenishment
activity is, however, time consuming and expensive; and its
feasibility is largely dependent upon the skill of the operator in
guessing just what is happening to the chemical solutions in the
processor, and in determining just what action is needed to
counteract and control observed trends. In addition, such manual
replenishment techniques are impractical when it is necessary to
control a film processor equipped with an automatic sheet or roll
feeding device, e.g., a feeder of the type disclosed in U.S. Pat.
No. 3,232,606.
In an effort to overcome some of the difficulties of manually
controlled replenishment systems, suggestions have been made
heretofore for so-called automatic replenishment systems. In such
automatic systems, some form of sensor is employed to monitor a
preselected parameter or parameters; and on the basis of the output
of this sensor, an attempt is made to effect appropriate chemical
replenishment. In some cases, the sensor is designed to optically
read a continuous control strip passed through the solution, or to
monitor one or more preexposed test regions of a sheet of film
being processed. As a practical matter, systems of this type
involve substantially all of the disadvantages described
previously, i.e., complexity, etc. Moreover, notwithstanding these
disadvantages, prior such automatic systems effect relatively
inaccurate replenishment since the information obtained from the
sensing or monitoring operation does not truly indicate the
character of the image throughout an individual sheet of film being
processed, or the character of the image in every sheet being
processed, or the amount of chemical which may or will have been
used up in the course of processing any one or a plurality of film
sheets.
Other so-called automatic replenishment systems suggested
heretofore have sought to monitor the physical level of the
processor solutions, and to effect replenishment by the use of
float control valves or the like; but systems of this type do not
reflect what is actually happening to the chemistry of the
solutions at all, and merely maintain given volumes of solution
rather than desired chemical concentrations. Still other prior
systems have sensed the physical size of a sheet of film being
processed, and have sought to control replenishment on the basis of
the area of material being processed. Such systems, however, are
also highly inaccurate since the amount of chemical replenishment
required is not a function of film area per se, but is primarily a
function of "exposed" film area. Size-detecting systems therefore
fail to determine the amount of chemicals which has actually been
used, and fail to supply information needed to maintain chemical
concentrations within desired limits.
The present invention, recognizing these disadvantages of manual
replenishment systems and so-called automatic systems suggested
heretofore, provides a new and far more accurate automatic
replenishment system adapted to compensate for chemical depletion
as a function of the optical density developed in every sheet of
image bearing photosensitive material being processed, and as a
function of the optical density throughout the complete are of each
such sheet of material.
SUMMARY OF THE INVENTION
The present invention comprises an apparatus adapted to determine
the image density variations throughout the complete area of a film
sheet after it has been developed in an automatic processor, and
arranged to generate an electronic signal commensurate with the
monitored image density. In this respect, the term "sheet" used
herein and in the appended claims is intended to encompass both
continuous and cut lengths of material, and the term "film" is
intended to encompass any suitable type of material requiring
processing. The complete areal image density variations of the film
sheet, thus monitored, provides a more accurate measure of the
degradation of the developer and fixer solutions in the automatic
film processing equipment; and the signal generated as a result of
the monitoring operation may accordingly be employed to control
proper replenishment of the developer and fixer solutions on an
automatic basis.
In effecting the foregoing functions, the present invention employs
a scanning system comprising a plurality of bundles of optical
fibers which are serially illuminated or scanned by a light source,
operative to cause an elongated, narrow beam of light to traverse
the complete width of a sheet of film after the film sheet has been
developed. Light passing through the developed film is detected by
a linear array of optical fibers located on the opposite side of
the film; and the detected light is then summed in a photocell or
like means. The steady state photocell current is balanced to zero
(or to a predetermined steady state value) by means of a current of
suitable magnitude and polarity from an external circuit so that
the output of the photocell (or any other appropriate means, such
as a photomultiplier tube) remains at a known steady state value
until the sensor light is attenuated by the passage of
image-bearing material.
The photocell is coupled to a first information accumulator or
integrator adapted to produce a signal commensurate with the
developed areas sensed on the film during a single scan of the film
sheet by the sensor. The output of this first integrator is sampled
after each lateral scan of the film, and the sampled output is
transferred to a second accumulator or integrator arranged to store
and aggregate information corresponding to a plurality of lateral
scans of the film sheet. The output of the second integrator is in
turn applied to a level detector and, when the output of the second
integrator reaches a preselected level, the level detector
transfers the accumulated information to a mechanical integrator
for still further accumulation. The use of such a mechanical
integrator relieves the need to hold large amounts of information
for long periods of time in an electronic integrator, and avoids
the possible loss of information which may occur, due for example
to leakage in the storage capacitor of such an electronic
integrator, over a long period of time.
The incremental information transferred to the mechanical
integrator is summed over a period of time; and when a preselected
level of information has been accumulated in the mechanical
integrator, a timer and replenishment solenoid valves are energized
and cooperate to transfer replenishment chemicals from storage
tanks to the processor tanks for a fixed interval of time and at
preselected flow rates. The flow rates may differ for the developer
and fixer replenishment respectively. At the commencement of this
fixed interval of time, the mechanical integrator is reset to zero
preparatory to the accumulation of further information needed for a
later replenishment operation.
The system of the present invention operates to cause chemical
replenishment of the developer (and, if desired, fixer) during a
fixed interval of time at a predetermined flow rate. The system
actually operates to determine just when (in terms of integrated
incremental image density) the said fixed time interval should
commence. The system, moreover, "post-adjusts," i.e., replenishment
occurs after a film sheet, or after a number of sheets, have been
developed; and as a result, the replenishment actually takes into
consideration the amounts of chemical depletion or degradation
which have occurred as a result of development and related
activities over an extended period of time.
The film reader, including the scanner and integrators to be
described hereinafter, may take various forms. Moreover, while the
film reader finds particular utility as a portion of an automatic
replenishment system such as has been described, the reader itself
may be employed in other environments, e.g., for purposes of merely
examining sheets of film or other image-bearing materials by the
transmission of light therethrough, or by reflection of light from
a surface thereof, to determine the average density over the entire
sheet, and/or the maximum density existing in the sheet, and/or the
minimum density existing in the sheet, and/or the image
characteristics at a particular portion of the sheet. Information
of this type is valuable in various environments, e.g., when it may
become necessary to reproduce the image under investigation; and
therefore the reader of the present invention finds utility in
environments other than the automatic replenishment control to be
described.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an automatic film processor
incorporating the automatic replenishment control system of the
present invention;
FIG. 2 is a schematic and circuit diagram of the automatic
replenishment control system of FIG. 1;
FIG. 3A and 3B are detail views of a light scanning arrangement
which can be employed in the present invention; and
FIG. 4 is an illustrative diagram of an alternative light scanning
arrangement which may be employed in the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring initially to FIG. 1, an automatic film processor
incorporating the automatic replenishment control of the present
invention may comprise a plurality of processor tanks comprising at
least one developer tank 10, at least one fixer tank 11, and at
least one wash tank 12. Exposed sensitized material to be developed
is fed in sequence through the tanks 10, 11 and 12 along a path of
the type generally designated 13 by means of an appropriate
transport system diagrammatically illustrated by rollers 14.
Squeegee rollers 15 are located downstream of the wash tank 12; and
the developed film is caused to pass through said squeegee rollers
for partial drying, whereafter the film is fed through a drier 16
for final drying and collection. Apparatuses of this general type
are in themselves well known.
In accordance with the present invention, a sensor arrangement is
provided, adapted to completely inspect each sheet of film
throughout both its width and length, to determine the different
optical or image densities developed in different areal portions of
the film by the processor action, thereby to provide a measure of
the amount of chemical which may have been used up in the course of
the development process. The sensor arrangement may take various
forms; and in the preferred embodiment shown in FIG. 1 comprises a
light projecting element 17 coupled to a scannable light source 18,
and cooperating with a light collecting element 19. As shown in
FIG. 1 the light projecting element 17 is disposed above the path
of travel of a sheet of developed film, whereas the light
collecting element 19 is disposed below said path of travel, and
light is projected through the developed film for monitoring
purposes. The sensor elements 17 and 19 are, moreover, located
between the pairs of squeegee rollers 15 at a position between the
wash tank 12 and drier 16. This particular location of the sensor
17--19 is advantageous since the squeegee rollers act as a baffle
to prevent light fogging of undeveloped film located upstream of
the sensor. Moreover, the film at this sensor location is already
developed and relatively dry and, being transported under some
tension, is somewhat constrained, thereby facilitating the making
of relatively accurate measurements of the image densities in the
film.
The light scanning source 18 may take various forms; and two such
forms are shown in FIGS. 3 and 4 respectively. The rate of scanning
is directly related to the transport speed of the film by coupling
the light scanning source 18 to the film transport system. In FIG.
1, this synchronization between the light scanning rate and the
film transport rate has been depicted by the diagrammatic
connection 20 between the scanning source 18 and squeegee rollers
15, which are in turn driven synchronously with the remainder of
the transport system.
As the developed film is fed past the sensor elements 17, 19 said
elements cooperate with source 18 to perform a 100 percent
inspection of the film in both width and length. More particularly,
the elements 17 and 18 cooperate with one another, and with the
synchronous drive from the transport system, to effect a plurality
of optical scans across the width of the film for each linear inch
of film travel. In one actual embodiment of the present invention,
the rate of scanning is 10 scans for each linear inch of film
travel; but other rates of scanning could, of course, be employed.
The amount of light which is intercepted by element 19 during each
individual scan, and during the several light scans, represents a
measure of the aggregated incremental densities developed in the
sheet of film; and this light is collected by element 19 and fed to
a control circuit 21 (to be described hereinafter in reference to
FIG. 2).
Circuit 21 continually monitors the image density of each sheet of
film developed, and the aggregate density of a plurality of such
sheets; and selectively operates a solenoid controlled valve 22
adapted to permit the feeding of replenishment chemical from a
reservoir or tank 23 via a manual valve 24, flow meter 25, and line
26 to the developer tank. A similar arrangement may be provided to
effect controlled replenishment of the fixer solution in tank 11,
but this has not been shown in FIG. 1 to simplify the drawings. In
actual practice, as will be described in greater detail
subsequently, control circuit 21 includes a timer element adapted
to open one or more valves such as valve 22 for a fixed interval of
time once the circuit determines that replenishment is needed.
Manual valve 24 is used during initial set up of the equipment, in
cooperation with flow meter 25, to fix precisely the rate of flow
out of tank 23 when valve 22 has been opened; and the several
elements thus cooperate with one another to produce a highly
accurate rate of flow for a precise period of time to developer
tank 10 when the sensor assembly and cooperating control circuit
determine that replenishment should be effected. It will be
appreciated that when replenishment of the fixer tank is effected,
it may be accomplished at a different flow rate from that of the
developer replenishment, but in a manner otherwise similar to that
already described.
The scanner assembly employed comprises, in accordance with a
preferred embodiment of the invention, a fiber optic line scanner
arranged to integrate photoelectrically the different optical
densities developed in different areal portions of each sheet of
image bearing photosensitive material, so as to provide a signal
useful in compensating for the resulting chemical depletion by
means of an automatic replenishment system. The principle employed
is to scan the full film width with a rectangle of light having
dimensions roughly 2.5 by 0.1 inches, said scanning being effected
at a pitch of 10 lines per inch of linear travel through the
sensor. The image modulated light is then transmitted to a
receiving photocell via a further fiber optics bundle 45 to provide
signals which are used in the manner to be described for control
purposes.
As shown in FIGS. 2 and 3, scanner element 17 may comprise a
supporting block into which are plugged one end of a plurality
(e.g., 10) of fiber optic bundles 30 formed of suitable glass or
plastic material. The other end of each bundle 30 is plugged into a
stationary light-tight lamp housing 31 provided, on its interior,
with a concentric drumlike shutter member 32 provided with three
apertures 33a, 33b, and 33c spaced 120.degree. from one another. A
lamp 34 is disposed within drum 32, said lamp 34 being energized by
a stable DC or high frequency AC source 35 to avoid light level
fluctuations. Drum 32 is driven by means of a shaft 36 mounted in
appropriate bearings 37 carried by housing 31; and shaft 36 is in
turn coupled to an appropriate driving element 38, driven in
synchronism with the processor transport system via an appropriate
chain drive or timing belt 39.
The several light bundles 30 are plugged into housing 31 (see FIG.
2) over a 120.degree. arc. Light emitted by lamp 34 and passing
through one of the apertures such as 33a, impinges on each of the
light bundles 30 in succession at the housing 31 end thereof as
drum 32 rotates, whereby a beam of light scans across the ends of
each fiber bundle. The 120.degree. disposition of the several
apertures 33a, 33b, and 33c further assures that as soon as the
light beam provided by one aperture leaves the last one of the
group of bundles 30, a beam of light from the next aperture
immediately commences a further scanning operation across said
bundle ends. This accordingly assures that the several light
bundles 30 are scanned repetitively and in sequence, with zero
flyback time.
Shaft 36 of the scanning source further carries a disc 40 having
three permanent magnets 41a, 41b, and 41c mounted thereon in
120.degree. spaced relation to one another. A pair of magnetic
proximity reed switches SW1 and SW2 are mounted adjacent disc 40
for selective actuation by magnets 41a etc., during each line
scanning operation. Each of the reed switches SW1 and SW2 is of the
single-pole double-throw type, and each is biased to normally make
with one contact, and to switch to the other contact momentarily
when a permanent magnet mounted on disc 40 passes adjacent to said
switch Thus, during the scanning operation effected by rotation of
drum 32, each of the switches SW1 and SW2 is periodically operated.
The function of these switches will become more readily apparent
from the description of FIG. 2 to be given later.
The fibers in each individual bundle 30 are, within the body of
sensor structure 17, fanned out to form a line. These individuals
linearly arrayed groups of fibers are designated in FIG. 2 as 30a,
30b, 30c, etc. In the particular arrangement shown in FIG. 2, it
has been assumed that the incremental optical densities in a sheet
of film 43 having a width of 24 inches are to be sensed; and ten
fiber bundles 30 are accordingly provided, each of which contains a
plurality of fibers which are individually fanned out into a linear
fiber array 30a etc., having dimensions roughly 2.5 inches by 0.1
inches so as to cover the complete width of the assumed sheet of
film. It will be appreciated, however, that different numbers of
fiber bundles 30, and different numbers of fibers within each
bundle 30a etc., may be employed to accomplish scanning of film
sheets having different widths, without limitation as to the width
of the sheet of film to be monitored, and the light scanning
arrangement is nevertheless such that each increment in width of
the film is scanned by light of the same intensity. This represents
a significant improvement over other types of scanning arrangements
which might be employed wherein light is, for example, projected as
a moving beam across the film or other material to be scanned. Such
projected light beams tend to exhibit intensity variations due to
the differences in distance between the light source and the point
of light impingement as the beam is scanned, particularly in the
case of scanning over very wide film areas.
Due to the fanning out of the fibers in each bundle, as each bundle
30 is illuminated by light from lamp 34 this illumination is
translated into a narrow rectangle of light directly above the
sheet of film 43. As the several bundles 30 are scanned in sequence
this rectangle of light progresses across the width of the film
and, after illuminating the last film segment, immediately reverts
to the first bundle for a further scanning operation. The light
transmitted through the sheet of film 43 is collected by a further
fiber optics arrangement comprising a supporting sensor structure
19 associated with a light collecting fiber optics bundle 45 having
the individual equal-length fibers thereof laid out along a line
underlying the several segments 30a, 30b etc., in the light
transmitting portion of the sensor. Thus the amount of light which
is transmitted to collecting bundle 45 during each scanning
operation varies with the image density encountered by the scanning
light source during each individual scan.
The light gathered by fiber optics bundle 45 from the underside of
film sheet 43 is passed through said bundle 45 and projected onto a
photocell 46, or onto any other appropriate light sensing element.
Photocell 46 is coupled to a resistive network 47 associated with a
potentiometer 48 adapted to balance out the steady state photocell
current to zero whereby the signal at point 49 remains at zero
until sensor light is attenuated by the passage of image bearing
material past the sensor assembly 17, 19. In the alternative,
potentiometer 48 may be so set as to continuously supply a small
signal, under otherwise quiescent conditions, to compensate for the
effects of developer oxidation taking place even in the absence of
any film developing activity.
If we now assume that a sheet of film 43 having a developed image
therein is passing through the sensor 17, 19, the sensor light will
be attenuated, during each scan, by the developed image. The amount
of attenuation will be dependent upon the various incremental
optical image densities encountered during a given scan; and the
aggregate attenuation will produce a signal of related magnitude at
point 49. The signal at point 49 is supplied to a commercially
available operational amplifier OA1 which includes a storage
capacitor selected from the bank of capacitors C.sub.1 by a switch
50. Each of the capacitors in the bank C.sub.1 is of different
value; and switch 50 is coupled to the incremental speed control
switch of the automatic processor transport system so that when the
transport speed of the processor is changed, the value of the
integrating capacitance selected for amplifier OA1 is also changed
proportionately. Amplifier OA1 thus acts as a fast integrator, and
the signal level at its output 51, corresponding to the net charge
on the integrating capacitor (C.sub.1) at the end of a single scan
line, is a function of the total image density seen by the sensor
during that particular scan.
Just before the end of each scan, the rotating magnet and
associated reed switch arrangement already described operates to
switch the blade of SW2 momentarily into contact with terminal 52
so as to transfer the output of fast integrator OA1 to a sampling
capacitor 53. Immediately following this, at the end of each scan,
the blade of switch SW1 is momentarily switched into contact with
terminal 52a so as to discharge the integrating capacitor in the
bank C.sub.1 thereby readying amplifier OA1 for the next subsequent
integration operation. Thus, the amplifier OA1 and the various
switches associated therewith cause each line of information to be
sensed and then transferred as a separate entity to sampling
capacitor 53.
The charge in capacitor 53 acts as an input to a second or slow
integrator or accumulator comprising a commercially available
operational amplifier OA2. Amplifier OA2 is connected as a
bootstrap integrator, or staircase generator, having a storage
capacitor C.sub.2; and the successive inputs to sampling capacitor
53 cause a negative-going staircase output voltage at output 54 of
slow integrator OA2. The magnitude of each step depends upon the
signal transferred to capacitor 53. The negative-going output
staircase of slow integrator OA2 continues to increase negatively
with each successive increment of information from fast integrator
OA1 until the negative potential at output 54 reaches the
triggering voltage of a voltage level detector employing a
commercially available operational amplifier OA3. In one embodiment
of the invention, slow integrator OA2 may be required to describe
something in the order of 40 -negative-going steps before this
triggering voltage is reached so that, in effect, slow integrator
OA2 acts to accumulate information corresponding to perhaps 40 or
more lines of information detected by the scanner.
When the triggering voltage of level detector OA3 is reached, a
relay coil 55 is energized so as to close contact sets 55a and 55b
associated therewith. The closure of contact set 55a operates to
discharge capacitor C.sub.2 associated with slow integrator OA2 so
as to restore the signal at output 54 to its datum level
preparatory to the accumulation of further multiline information by
OA2. The closure of contact set 55 b completes a circuit from a
capacitor 56 through a drive magnet 57 associated with a stepping
switch or mechanical integrator 58 of the ratchet and pawl type.
Capacitor 56 has a charge thereon as the result of its connection
to a DC source 56a, whereby completion of the circuit mentioned
causes drive magnet 57 to be pulsed, thereby stepping the movable
switch arm 58a of mechanical integrator 58 from one to the next of
a plurality of mechanical contacts 58b, 58c etc. against the
restraint of a return spring 59. The DC source and capacitor
arrangement 56, 56a is utilized to assure that drive magnet 57 is
merely pulsed upon closure of contact set 55b, thereby preventing
any damage to drive magnet 57 due to any sustained energization
thereof.
It will be appreciated that the operation of contact set 55a, in
removing the charge from capacitor C.sub.2 of slow integrator OA2,
simultaneously reduces the input to level detector OA3 below its
triggering voltage. As a result, the mechanical integrator 58 is
caused to move through one mechanical step when the output of slow
integrator OA2 reaches a level corresponding to a plurality of
lines of information; and the system is then caused to assume a
condition proper to the summing of a further plurality of lines of
information.
Mechanical integrator 58 acts as an inexpensive, longterm memory;
and each stepping of that mechanical integrator corresponds to the
accumulation of information from a plurality of scan lines. While
it is possible to accumulate large amounts of information in a
capacitor such as C.sub.2, there is always the possibility that
such a capacitor may leak over a long period of time whereby
attempts to accumulate and store information in a capacitor for an
extended period of time may result in some loss of information. By
using the mechanical integrator 58, it is possible for the
equipment to be turned off and later turned on without significant
loss of information, and the possibility of error due to capacitor
leakage is minimized.
A selected fixed contact 60 in mechanical integrator 58 is coupled
to a further delay coil 61 so that when mechanical integrator 58
has been stepped through a desired number of increments, a circuit
is completed through switch arm 58a of said mechanical integrator
and contact 60 to relay coil 61 to cause said coil to be energized
by a source 62. Energization of relay 61 closes contact sets 61a,
61b, and 61c thereof.
Closure of contact set 61a establishes a holding circuit for relay
coil 61 via a normally closed switch 62 to assure that relay coil
61 remains energized so long as switch 62 is closed.
Simultaneously, closure of contact set 61b completes a circuit from
capacitor 63, which was previously charged from a source 64 (for
reasons similar to those given with respect to elements 56 and 56a)
to cause a reset coil 65 associated with mechanical integrator 58
to be pulsed. Reset coil 65 releases the pawl in the ratchet and
pawl mechanical integrator 58 so that spring 59 may operate to
return the mechanical integrator to its zero or starting position
preparatory to the accumulation of further increments of
information. The closure of contact set 61c completes a circuit
from AC source 70 to a timer T and a solenoid 71 wired in parallel
with one another.
Solenoid 71 operates to open the valve 22 (see FIG. 1) so as to
cause replenishment fluid to flow at a previously set rate to the
developer tank. This flow continues so long as timer T remains
energized. Timer T is a commercially available unit and comprises a
synchronous motor having a mechanical detent 72 which operates to
open switch 62 after a precise time interval. Other forms of timer,
including solid-state timers, may be employed. When the time
interval established by timer T elapses, the normally closed timer
switch 62 is opened, thereby deenergizing relay coil 61 by
simultaneously breaking the holding circuit for said coil 61, and
deenergizing timer T and solenoid 71. The entire system thus
operates to transfer replenishment chemical to the developer (and,
if desired, fixer) tank of the processor for an interval of time,
and then operates to reset itself to an initial or datum condition
preparatory to reception of the next replenishment control signal
from mechanical integrator 58.
It will be noted that, by the arrangement described, replenishment
always occurs during a fixed time interval and at a fixed flow
rate. The system actually operates to determine just when, in terms
of integrated image density, the said fixed time interval should
commence. If a particular film sheet, or a relatively small number
of successive sheets, being fed through the processor exhibits
relatively high integrated image density, replenishment may
commence a relatively short time after the processing operation
starts. On the other hand, if the sheets being fed through the
processor exhibit relatively low integrated image density,
commencement of the replenishment operation will be deferred
correspondingly. In all cases, however, replenishment takes place
when the accumulated or integrated image density of one or more
sheets indicates that such replenishment is needed. It will be
noted moreover that the system operates to "post-adjust," i.e.,
replenishment occurs after a film sheet, or a number of sheets have
been developed; and the replenishment is governed by the nature of
the images in the sheets previously developed. This avoids
difficulties which have been present in prior systems where
attempts have been made to estimate the amount of replenishment
which will be needed due to the processing of a sheet or sheets of
material, prior to the time the sheet is actually developed by the
processor.
The various operational amplifiers, the mechanical integrator, the
timer arrangement, etc., of the apparatus shown in FIG. 2 are in
themselves all conventional and commercially available; and various
modifications can be made in the mechanical and electrical details
of the circuit without departing from the concepts of the present
invention. Moreover, while the fiber optics arrangement of the
sensor 17, 19 represent a preferred embodiment of the present
invention, other types of scannable sensors can be employed if
desired. One such alternative scanner is shown diagrammatically in
FIG. 4.
In the arrangement of FIG. 4, the several linear arrays of light
fibers 30a, 30b, etc., of the FIG. 2 arrangement are replaced by
individual shaped lucite light distributors 75, 76 etc., each of
which may be supplied with light from an appropriate scanning
source via fiber bundles 77, 78, etc., or analogous such light
transmitting means. The several light distributors 75, 76, are each
shaped to define a lower, elongated, relatively narrow light
transmitting area corresponding in dimension to the fanned-out
linear array of fibers already described in reference to FIG. 2;
and the side of said light distributors are coated with reflective
material as at 75a, 76a, etc. Such light distributors or light
concentrators are in themselves known; and reference is made, for
example, to Miller U.S. Pat. No. 3,256,385 for a discussion of such
structures.
The pickup portion 19 of the sensor (FIG. 2) may be replaced by a
lucite light collector 79 having plural segments 79a, 79b, etc.,
associated respectively with the light distributors 75, 76, etc.
While the light distributors 75, 76, etc., should be separated from
one another to permit appropriate scanning of the light as light is
transferred from one to the next of said distributors, the several
segments 79a, 79b, etc., can be interconnected to one another as
shown in FIG. 4 since the essential purpose of the light collector
79 is to merely accumulate information from all of the light
distributors and transfer such information to an appropriate
detecting and integrating arrangement of the type described.
It should further be noted that while the several scanner
arrangements described have been depicted as scanning at the input
side, and merely collecting light at the downstream side of the
scanner, it is entirely possible to provide a continuous line of
light at the input side (e.g., from an appropriate elongated line
source of light extending completely across the sheet of film) and
to effect scanning at the output side of the scanner. Moreover the
scanning, whether accomplished on the input or output side, can be
effected by any of various scanning arrangements already known to
those skilled in the art; and the scanner need not therefore take
the particular form shown and described in reference to FIGS. 3A
and 3B.
While I have thus described preferred embodiments of the present
invention, many variations will be apparent to those skilled in the
art, and certain of these variations have already been described.
It must therefore be understood that the foregoing description is
intended to be illustrative only and not limitative of my
invention; and all such variations and modifications as are in
accord with the principles described are meant to fall within the
scope of the appended claims.
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