Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a method and apparatus
for developing diazo film.
Dia20 sensitized papers have been used for a long
time for making duplicate copies of originals, normally by
contact printing, and the subsequent development of the
exposed diazo paper in an aqueous ammonia vapor atmosphere.
In such an application, resolution requirements and deve-
lopment times are not critical. More recently diazo sen-
sitized films have received increasing attention as an ideal
medium for making microfilm or microfiche masters and,
perhaps more importantly, duplicates thereof because o the
relatively low cost of such film, its high resolution
capability, etc. For such applications, however, increasingly
stringent demands are made on the film developing process,
particularly as to the speed with which it can be accom-
plished so as to enable an efficient, high volume production
of diazo film copies from a master, for example.
In this~regard, problems have been encountered in
the~past. Ir~ order to attain short development times for
diazo film, it was heretofore thought necessary that the
development t~ke place in a high pressure ammonia atmos-
phere. In general, the pressures that were considered
necessary~are substantially above, e.g. several times, the
atmospheric pressure and they ranged up to as high as 1,000
psi or more. For example, U.S. Patent 3,411,906 issued to
IBM November l9r 1968, speaks of ammonia pressures in the
;range of between S0 to 1,000 pSl. ~ittle attention was paid
to the actual design~of the developing chamber into which - -
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the ammonia is introduced other than to maintain the volume
relatively small for the obvious expedient o l1miting the
amount of ammonia that is expended in the developing process.
From a practical view, however, such high pressure
requirements represent severe drawbacks, particularly in
connection with a continuously operating diazo film deve-
loper since the exposed film must be transported from theexterior into the high pre~sure atmosphere. For one,
ammonia leakage is quite unacceptable because o its noxious
odor and the potential health hazard it represents if
present in appreciable concentrations. Further, it is
notoriously difficult to seal a pressurized chamber if
contLnuous access to its interior is required unless the
ammonia in the chamber is evacuated each time a film is
inserted therein or withdrawn therefrom. This, however, is
not compatlble with a hlgh speed, high volume operation.
Although the above-referenced U.S. patent does not
concern itself with the actual chamber construction and is
not concerned with the above summarized difficulties of
operating it, another U~S. Patent (No. 3,364,833, issued to
IB~ January 23, 1968) proposes the construction of a diazo
film deve]op1ng de~ice comprlsing a sealed chamber defined
by a hase having a cavity dimensioned to receive the Eilm
and a cover that is bolted and sealed against the base. The
space of the cavity is kept as small as possib:Le and once it
is sealed, the air therein is evacuated and replaced with
high pressure ammonia to develop the film. ~lthough this
device not doubt assures the ful1 and complete development
of the film and, if operated alon~ the lines suggested in
the earlier referenced U.S. patent yields short development
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~ times, the insertion and remo~al of the film from the cavity
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ment time for the film by a very large factor. Thus, the
device disclosed in U.S. patent 3,364,833 may be ideally
suited for developing an individual diazo film from time-to-
time; but it is unsuitable for continuous, large volume
operations.
Thus, inspite of the advantages afforded by diazo
film for high resolution, high volume applications such as
for the duplication of microfiche masters, there is pre- -
sently no technologically feasible device for economically
mass developing such film.
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The present invention provides a diazo film
developing method and apparatus which dramatically departs
from prior art concepts for the construction and operation
of diazo film developers to render them compact, efficient
and easy to operate at even very high film output volumes.
This is accomplished by dispensing with the high ammonia
pressures heretoore thought nacessary to achieve short
developing times~ Instead, in accordance with the present ~ .
- invention, the film is developed in aqueous ammonia vapor at
a pressure which does not substantially exceed atmospheric
: pressure. For purposes of the present invention, this means
: that the pressure is only slightly higher than atmospheric :
pressure, by an amount no more than that required to in~
troduce the vapor into the developing chamber. Thus, the
pressure is typically in the area of no more than a Eew, say
1 to 2 inches of water column above atmospheric pressure and
in any event, it is substantially less than the heretofore
suggested ammonia pressure and, therefore, will always be
less ~han one atmosphere ~about 14 psi) above atmospheric
20:~ preSsure~
Thus, in a first aspect the invention is a method
for developing diazo film having a substrate and an emul.si.on
carried on a side of the substrate, the method comprising
the steps of: placing the ilm i.n a chamber having physical
~chamber dimensions only slightly larger than the physical
~: dimensions of the filmi introducing aqueous ammonia vapor
into the chamber at a pressure not substantially greater::
than atmospheric pressure so that the ammonia vapor contacts
the film emulsion:~and remo~ing the .ilm from the chamber
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after a relatively shor-t time interval of no more than a few
seconds.
This low pressure ammonia vapor is combined with a
minimal developing chamber volume which is no greater than
that required to conveniently pass a film to be developed
through the chamber. The low pressure ammonia vapor and
small developing chamber volume is further coupled with
relatively low operating temperatures in a range of between
about 150F to 200F and, preferably, between about 175F to
10 190F so that the emulsion layer on the film is not softened
by heat. In this manner, moving contact between the film
and in particular its emulsion and components of the chamber
will not damage the emulsion. This facilitates the mini-
mization of the developing chamber volume since an actual
15 contact between the moving film emulsion and chamber walls
does not adversely affect the imayes on the film. In fact,
applicants presentLy believe that such a moving contact
between the emulsion and chamber walls, at least so long as
it takes place intermittently, enhances the development of
20 the~film by more intimately subjecting the emulsi.on to the
ammonia vapor and removing from the emulsion any expended
ammonia.
In a second aspect, tha invantion is apparatus Eor
developing diazo film comprising means defininy a developing
25 chamber~and including first and second, spaced apart, ~;
substantially parallel surfaces, a spacing between the
surfaces exceeding a thickness o the film by no more than
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~ an~amount requlred to readily move the Eilm through the
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chamber; means defining an intake opening for introducing
the film into the chamber and for removing it therefrom;
means for movlng the film through the opening and into and
out of the chamber so -that an emulsion side of the film
passes immediately adjacent one of the surfaces; and means
for applying relatively low pressure aqueous ammonia vapor
into a space between the film emulsion and the one surface;
whereby a rapid, low a~nonia pressure vapor developing of
the emulsion is effected.
In a practlcal embodiment such a spacing is
normally between about two to about eight times the film
thickness, which a spacing of about 0.020" being presently
preferred because of the ease with which the component
making up the chamber can be manufactured, the ease with
15 which the ~ilm can be transported between the surfaces in
actual use, and the relatively very low volume exhibited by
a chamber having such dimensions.
Eurther, the pre.sent invention contemplates that
the film~is advanced~in a downstream direction through the
~ 20~ :chamber at a speed~:so that the stay time for (any part of)
: the film does not subst.antially exceed a ew seconds, say
five seconds and, preerably, so that the stay time is no
more than about one or two seconds. Aqueous ammonia is
introduced into the chamber from the chamber surface which
~ 25 faces the emuls~ion slde oE the film. The ammonia vapor is ;;.
; : of substantially atmospheric pressure, that is it is only
slightly, e.g. a few inches o:E water column above atmos-
pheri~c pressure.
: The vaporization and (mlnimal) pressurization of
;~ 30 the ammonia is achleve~:by provid.ing a heating platen which :
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defines the surface that faces the emulsion side of the film
and forming an open conduit therein which extends through
the film facing surface of the platen. The platen is heated
to the above-stated developing temperature and aqueous
ammonia is flowed into the conduit where it is vaporized due
to the ele~ated temperature~ This results in the above-
discussed slight rise in the ammonia vapor pressure of a few
inches of water column so that the vapor discharges from the
conduit into the chamber. In a preferred embodiment of the
invention~ a metered amount of aqueous ammonia is pumped
into the conduit for each film to be developed. This can be
done by using an appropriately designed pump or by sensing
an approaching ~ilm and intermittently actuating a metered
aqueous ammonia pump in response thereto.
In a preferred embodiment the apparatus of the
present invention, generally speaking, comprises a housing
that defines an upstream film intake opening and a down-
stream film outlet opening~ E`irst and second platens are
disposed within the housing and opposing, parallel first and
second surfaces of the platens are positioned to receive
incoming film from the intake opening and to discharge
outgoing film to the outlet opening~ Means is further
provided Eor maintaining the spacing between the platens in
the above-outlirle~ range so as to permit the uninhibited
passage of the film between the surfaces while minimizing
the spacing between the surfaces and, therefore, the volume
of the developing chamber defined by the space
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1¦ between the platens. Pairs of c~operating rollers advance
2 the film (with its emulsion side facing the first surface)
3 in a downstream direction from the~intake opening through
4 the chamber to the outlet opening.
5¦ The present invention further provides means for
¦ sealing the developing chamber from the intake and the
71 outlet openings. ~he sealing means comprise sets of cooperating,
8l elongate, opposite rollers disposed adjacent and parallel to
9 the openings for receiving and discharging the film. The
rollers have resilient surfaces in mutual contact and low
11 ~riction, e.g. Teflon (a registered Trademark of the Dupont
12 de Nemours Company) strips are sealingly disposed in correspondin
13¦ grooves of the housing, are arranged parallel to the rollers,
14 ¦ and are resiliently biased thereagainst so as to form a seal
15l therewith and prevent the escape o ammonia vapors through
16 the openings to the exterior. Although such a seal would
17 not be sufficient to withstand the hiqh ammonia pressures
18 found in prior art diazo film developing systems, it is
19~ ~ suflicient to form a seal during the low pressure operation
of the apparatus Oe the present invention so that no noxious
21 ammonia odors escape. Consequently, a device constructed in
22 accordance with the invention can be operated in closed
23 rooms with little or no separate ventilation without representing
241 a health ha~ard or creatlng an objec*ionable stench or odor.
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1 Alternatively, the spring biased strips which
2 engage the resilient roller surfaces may be replaced with
3 relatively flexible Teflon sheets ~hich extend over the
4 length of each roller. One portion of the sheet is rigidly
3 secured, e.g. bolted against a platen while the other portion
6 of the sheet overlies the respective roller. A flexible
7 leaf-spring is similarly bolted against the platens, preferably
together with the Teflon sheet, and it is arranged so as to
3 bias the associated sheet against the roller surface to
thereby establish a seal between the developing chamber and
11 the exterior.
12 Further, the apparatus of the present invention
13¦ includes a heater for heating the first platen to a temperature
14 1 in the above-stated range and at least one conduit is formed
15¦ in the first platen, communicates with the ~irst surface and
161 is located pro~imate the upstream end thereof. Pump means
17¦ supplies to the conduit aqueous ammonia and means is provided
18¦ for evaporating the ammonia therein to effect a discharge of
1~¦ the ammonia vapor from the conduit at the above-discussed
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~¦ low pressure. Thus, as the diazo film advances through the
21 developing chamber, it is contacted by the ammonia vapor and
31 causes the formation of a turbulent ammonia vapor layer
4l between at least portions of the emulsion and the first
~ surface to effect the rapid developing of the emulsion at
6 low temperatures and pressures.
7 ¦ The first surface preferably includes a transverse
8 groove which fluidly communicates with the ammonia conduit
9¦ to effect the distribution of the vapor over the full film
10¦ width. Additional grooves downstream of the first mentioned
11 1 groove enhance the developing speed believed to be at least
12 ¦ in part caused by the increased turbulence in the ammonia
13 ¦ vapor which is caused by such grooves.
14 ¦ To further enhance the developing process the film
15 ¦ itself is preferably preheated before. it enters the developing
16 ¦ chamber. In a preferred e~bodiment of the invention, this
17 ¦ is accomplished by passing the film between two platens
18 ¦ heated to the same tempexature as the first platens, and
19 ¦ disposed upstream of the developing chamber.
20 ¦ From the foregoing summary, it is apparent that
21 ¦ the present invention achleves the high speed developins of
22 ¦ diazo-~ype fllm without having to xely on the high pressures
23 I required in prior art diazo developing systems. This,
24 coupled with the small chamber dimensions enables the very
25 ¦ rapid development of microfiche, ofte.n in less than one
26 ¦ second. It~conserves ammonia and, most importantly, it
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l enables a very simple construction of the chamber and the
film transport mechanism while assuring an effective seal to
3 prevent the escape of ammonia into ~the surrounding atmosphere.
4 Therefore, the present invention is ideally suited for
g incorporatlon in microfiche duplicators and its wide acceptance
6 ¦ hroughout the industry is fully enticipated.
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Aspects of -the invention are illustrated, merely
by way of example in the drawings.
In these drawings:-
Figure 1 is an overall side elevational view, in
section, oE a diazo film developer constructed in accordancewith the present invention for incorporation in a microfiche
copier or the like;
Figure 2 is a front elevational view, in section,
of the developer shown in Figure 1 and is taken on line 2-2
of Figure l;
Figure 3 is an enlarged~ schematic side eleva-
tional view of the developing chamber shown in Figure l;
Figure 4 is a schematic plan view of the platen
defining the side of the chamber shown in Figure 3 which
faces the emulsion side of the film;
Figure 5 is a fragmentary, side elevational view,
: similar to Figure l and shows another embodiment of the
present invention; and
~ Figure 6 is a fragmentary front elevational view
: ~ 20 illustratlng the manner in which the developing chamber
formed between the platens is sealed in a longitudinal
:: direction.
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3 Referring to the drawings, a diazo film developer
4 2 may comprise part of a mi~rofiche duplicator 4 (schematically
~ shown only) which includes suitable means for exposing such
6 film and for thereafter advancing it towards the developer. The
7 developer itself generally comprises a housin~ 6 which has upright
8 side walls 8 and spaced apart end walls 10 and which is
91 normally hori~ontally positioned. The end walls 10 dein~
~1 an upstream intake opening 12 through which a microfiche 14
11 ¦ may en~er the interior of the housing. The other, opposite
12 ¦ end wall of the housing defines an outlet opening 16 which
13 ¦ is aligned with the in~ake opening. A flat cover 18 is
14 ¦ placed over the housing an~ a gasket 20 seals the interior
~ ¦ space from the exterior. Suitable closure hinges 22 retain
16 ¦ the cover to the housing while they assure the formation of
17 ¦ a seal between the cover and the gasket.
18 ¦ In the presently preferred embodiment of ~he
19 I lnvention~the housing interior is divided into a pair of
20~ ¦ serlally arranged upstream and downstream cavities 24, 26 by
21 ~a first pair of cylindrical, parallel drive rollers 28
22l positioned at a~out the center of the housing interior. A
231 second and a third pair 30, 32 of like drive rollers is
24¦ disposed adjacent the intake and the oulet openings, respectively
251 The rollers are~in mutual contact along a line aligned with
~61 the center o~ the intake and the outlet openings, they are
~i¦ constructed of a resilient material and they are biased
28¦ against each other so that the rollers form an airtight seal
291 between them.
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1 A groove 34 in the housing is adjacent and parallel
Z to each roller of the second and third roller pairs. Each
3 such groove receives an elongated low friction, e.g. Teflon
4 strip 36 which is biased against the periphery of the adjacent
5 ¦ roller by a xesiliently compressible member 38 such as a
6 ¦ foam rubber pad. The sealing engagement of the rollers
7 themselves and their sealing engage~en~ of the low friction
8 strips 36, seals ~he housing interior from the intake and
q ¦ outlet openings 12, 16. The rollers are further journaled
10¦ in bearings (not shown) carried by the housing side walls 8
11 ¦ which form a seal against the end faces of the rollers. A
121 drive, such as a chain-or sprocket drive (not shown) rotates
13 ¦ the rollers of each pair in opposite direction.s so that a
14 ¦ micrvfiche 14 placed between the upstream, second roller
15 ¦ pair 30 is grasped and advanced in a downstream direetion
16 ¦ into the first, upstream housing cavity 24. Roller pair 28,
17 ¦ which may~be sealed against the housing and the cover in the
18 ¦ above descrlbed manner with suitably placed seal strips 40,
19 ¦ thereafter grasps the downstream moving fiche and advances
20 ¦ it towards the third roller pair which discharges such film
21 ¦ through outlet opening 16 into a receptacle 4~. It will be
22 ¦ noted that during this transport of the film the housing
23 ¦ i~terlox remains fully sealed irrespective o~ ~he speed
24 ¦ and~or frequency ~ith which fiche is fed through the developer.
25 ¦ In the prese~tly preferred embodiment of the
26 ¦ ~lnvantion the upstream cavity 24 is utilized for the preheating
27 ¦ or microfiche 14 before it is developed in the d~wnstream
28 cavity 26.~;~For this purpose, a pair of parallel, opposing
upper and lower heating platens 44, 46, respective}y are
placed in the ups~ream ~avity. The lower platen rests in a
31 ~ rectangular~grOove 48 on ~a raised frame 53 projectins from a
3~1 bottom plate 50 of the housing and spaces the platen therefrom
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1107il6
1 so that a plate heater 52 can be attached to the underside
2 I of the platen for heating it to the desired temperature as
3 ¦ is further discussed below. Edges 54 ~shown in Fig. 2 only)
4 of the platens overlap, are raised and provided with inter-
engaging grooves to maintain the platen in mutual alignment
6 and at the desired spacing so that oppos;ng platen surfaces
71 56, 58 are spaced apart a sufficient distance to permit the
8 ¦ passage of a microfiche therebetween. In a typical embodiment,
9 ¦ the spacin~ is approximately 0.02". Grooves 60 may be
I0 ¦ formed in the platen to pxevent the adherence of the film to
11 ¦ one or the other. Further, the edges are spaced apart so that
12 the effective width of the opposing platen surfaces 44, 46 is
13¦ just slightly larger than the width of the fiche 14.
14 ¦ A pair of generally Z-shaped leaf-springs is
15 ¦ mounted, e.g. welded or bolted to the underside of cover 18
16 ¦ and, when the cover is secured to the housing, exerts a
17 ¦ downward pressure against the upper platen 4~ so as to
18 ¦ maintain it in firm contact with the lower platen~
19 ¦ A second pair of developing platens G4, 66 is
~0 ¦ disposed in the downstream cavity 26. The construction of
21 ¦ the developing platens is generally similar to that of
~2 ¦ heating platens 44, 46. Thus, the lower platen rests in an
23 ¦ other rectangular groove 48 formed in a raised frame 53 so
24 I as to provide space for a heater 6~ attached to the underside
25 ¦ of the lower plate. The opposing surfaces 70, 7?. of the
26 I~developing plat~ens define between them a ~e~eloping chamber 85.
27 I Their spacing "T" is closely controlled and in the presently
28 preferred embodiment is 0.02" for accommodating microfiche
29 ~ 14 having a thickness "t" o between 0.003 to about 0.007
At the indicated dimensions microfiche is readily
transported in a downstream direction, to the left
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1 as viewed in Figs. 1 and ~, without undesirable interference .
2 from the opposinq platen surfaces.
3 The lower platen includes a first groove 74 adjacen~
4 the upstream end of the platen which extends over the full
effective width of the platen and which ls convexly curved
6 when viewed in a downstream direction, that is downwardly as
7 seen in Fig. 4. Additional, similarly shaped gxooves 76 are
8 disposed in the lower platen and arranged downstream of
~ groove 74. An open conduit 78 is formed in the lower platen
10¦ 66 and terminates at about the bottom center of groove 74.
11 ~ Thus, it is also located adjacent the upstream end of the
121 lower platen. The conduit is connected with an aqueous
13¦ aI~monia reservoir 80 via a metering pump 82 and a valve 84
~4¦ 50 that upon the actuation of the pump aqueous ammonia i5
15¦ flowed into the conduit. The earlier mentioned Z-shaped
16¦ leaf-sprinqs 62 are employed to bias the upper developing
17 ¦ plate 64 downwardly against the lower plate when cover 18 is
18 ¦ closed.
19 ¦ Turning now to the operation of the developer 2,
Z0 ¦ heater control 86 is initially actuated to energize heater
21 ¦ 52 of the lower preheating plate 46 and heater 68 o~ the
22 ¦ lower developing platen 66. In this connection, it should
~3 ¦ also be noted that a heater may also be applied to the upper
24 ¦ platen.s 44 and 64 although under normal operations of the
developer that i5 not necessary. T~e heater control maintains
26 the platen temperature w.ithin the desired ranqe, e.g. between
2~ 150F to 200F andj preferably in the vicinity of 175F to
8 ¦ 190~F.
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1 Metering pump 82 may be selected so that it pumps
2 a ~ery low volume of aqueous ~nonia which is selected to
3 provide just enought ammonia to deuelop the fiches at whatever
4 rate they pass through the developing chamber. Alternatively,
~I the met~ring pump may be an inte~mittently operating pump
61 which is selectively activated in response to an approachi~g
7 ¦ microfiche 14. For that purpose the microfiche duplicator
8 ¦ 4 includes a sensor 88 (such as an optical sensor, for
example~ which is operatively coupled with the pump and
101 activates the pump each time a microfiche approaches housing
11 ¦ intake 12, for example, to flow a metered amount of aqueous
1~¦ ammonia to conduit 78. In an alternative operational mode
13j the sensor 88 may be coupled ~lth the valve 84 downstre~m of
14 ¦ pump 82 to temporarily open ~he valve to flow the desired
15 ¦ amount of ammonia to the conduit.
16 ¦ The conduit has a configuration so that ammonia is
17 ¦ heated to about the temperature of the platen while in the
18 ¦ conduit~ This results in the evaporation of the ammonia
19 ¦ therein and the above-discussed slight pressure build up so
20 ¦ that ammonia vapor escapes from the end of conduit 78 which
~1 ¦ terminates in the upstreammost groove 74. When the platen
22 ¦ is operated at the stated temperature range and the conduit
23~ has a diameter of 1/16ths inch, a conduit length within the
2~ platen of 2-1/2 to 3 inches is sufficient to effect the
25¦ desired evaporation of the ammonia.
26¦ The drive ~not separately shown) for roller pairs
27¦ 28, 30 and 32 may be continuously or intermittently operated,
28¦ in the latter case it i5 suitably coupled with sensor 88.
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1 A microfiche 14 ~o be developed which approaches
2 intake opening 12 triggers sensor 88 and causes a meterPd
3 amount of aqueous ammonia to be flowed to conduit 78 where
4 it evaporates and escapes into the developing chamber for
5 the film. Since there is a necessary lag between the introductio
6 of aqueous ammonia to the conduit and i~s evapora~ion the
71 pump is operated a short time period before the fiche arrives
at the chamber.
9¦ Once the leading edge of the fiche is grasped by
~o¦ roller pair 30 the fiche is driven in a downstream direction
11 ¦ through the space between the heating platens with its
12l emulsion side 30 facing downwardly, that is oriented so that
13 ¦ it faces the lower, heated platen 46. $he fiche, and in
t4 ~ particular, the emulsion carried thereon is heated to about
15 ¦ the temperature prevailing in the de~eloping chamber. After
16 ¦ its leadlng edge issues from the downstream end of the
17 ¦ heating platen roller pair 28- advances it into and through
1B ¦ developing chamber 85.
19 ¦ Since the developing chamber has a height which is
20 ¦ only slightly greater than the thickness o the fiche the
21 ¦ downstream movemenk of the latter causes a great deal of
2Z ¦ turhulence in the alNmonia vapor escaping from conduit 78
23 ¦~ against the emulsion side of the film. Frequently, the
24 ¦ emulsion side will either contact portions oE the opposing
25 ¦ platen surface 72 ox pass closely adjacent to them to
26 ¦ furthex increase the turbulence of the ammonia vapor.
27 Additionally, as it moves over the sur~ace and the grooves
2B therein, the ammonia vapor therebetween retains its turbulence.
~9 It is believ d that this ac~ion provides repeated access for
fresh ammonia vapor to the film emulsion and significantly
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1l contributes to its the high speed development. The fully
2 developed film is then discharged from the developer into
3 receptacle 42.
4 For the above-outlined developing parameters, it
5 has been found that developing times of as little as one
6 second, or in some instances, even less than that, can be
71 achieved so that the film can be moved through the developer
8! at relatively high speeds~
gl This is achieved with a very low pressure ammonia
vapor which is readily sealed so that practically no am~onia
11 odors are noticeable even in close proximity to the developer.
12 To remove ammonia condensate from the housing
13 interior a drainage opening 94 is preferably provided beneath
14 developing plate 66 which is connected with a condensate
receptacle 96 via a hose 98 or the like. It should further
16 be observed that by placing the Z-shaped leaL-springs 62
17 over the gap between the respecti~e ends of the developing
1~ plates and the adjacent roller pairs 28, 30 any ammonia
condensation which may form on the underside of cover 18 is
201 guided along ~he spring onto the top developing plate, from
21 1 where its flow may be guided towards drain 94 via the sides
22¦ of the platens to pre~ent ammonia droplets from contacting
23 ¦ the film. F'urther, to evacuate all ammonia vapors from the
24 ¦ housiny interior preparatory to opening cover 18, an air
25 I blower lO0 is provided to force air into the interior and to
26 thereby correspondingly force the ammonla vapors through the
2-~¦ drainage opening 94 into condensate receptacle 96 where it
281 can be absorbed in a suitab1e liquid, e.g. water bath.
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1 ¦ Referring to Figs. 5 and 6, in an alternative
21 ~mhodiment of the inventionl a developer 102 again comprises
31 a pair of opposite upper and lower platens 104, 106 which
are spaced apart as above-described, e.g. 0.20" so as to
~¦ form a gap 108 through which the film passes as it is being
6 ¦ developed~ The lower platen includes one or more transv~rse
7 ¦ grooves 110 connected with an aqueous ammonia supply (not
~ ¦ shown in Figs. 5 and 6) in the ahove-described manner. A
9 ¦ pair of film advancing rollers 112 i~ positloned adjacent
: 10 ¦ the downstream end and the upstream end (not shown in Fig.
11 ¦ 5) o~ the platen. The rollers are rotated in the above-
12 ~ described manner to grasp the film and advance it in a
13 ¦ downstream direction.
14 ¦ ~he rollers are positioned as closely as possible
15 ¦ to the respective ends of the platens. Instead of the earlier
16 ¦ described seal strips, relatively thin and flexible sealiny
17 ¦ sheets 114 are provided. Each such sealing sheet has a
18 ¦ length equal to the length of the rollers and a width so
19 ¦ that a first portion 116 can be secured with bolts 122 to an
; 20 ¦ upper side 118 of the upper platen 104 or a lower side 120
21 ¦ of the lower platen 106~ A second portion 124 of the sealing
22 ¦ sheet extends over ~he xespective roller 112.
23 ¦ A generally Z-shaped leaf spring 126 has a horizontal
24 ¦ leg 128 secured to the platens with bolts 122, an upwardly
25 ¦ extending portion 130 and a generally horizontally disposed
2Ç ¦ spring arm 132 which overlies the sealing sheet portion 124
27 ¦ and which biases that portion into contact with and generally
28 ¦ conforms it to the perlphery of the respective roller so
29
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1 that there is a substantial contact area between thP ~ealing
2 sheet and the roller. A seal is thereby established between
3 the developing chamber, that is between gap 108 and the
4 space between the ends of the plants and the rollers, and
~ the exteriox. The leaf-spring 126 assures a continuous
6 contact between the sealing sheet 114 and the roller and
prevents the escape o~ aqueous ammonia vapors, particularly
8 in instances in which the developing chamber is operated at
1 9 the above discussed low pressures.
Further, a longitudinally extending gasket 134,
11 which may have a circular cross-section similar to the
12 cross-~ection of a standard O-ring, is placed between the
13 upper and lower platens 104 and 106 to positlvely prevent
1~ ¦ the escape of a~monia vapors from the developlng chamber. In
15¦ this manner, the developing chamber is completely sealed,
16¦ even from the surrounding housing 136 to minimize ammonia
17¦ consumption, to facilitate the ease with which spent ammonia
1~1 can be withd~awn from the developing chamber, and to prevent
191 the escape of ammonia vapors upon the opening of housing
1 201 cover 18 ~shown in Fig. 1) without requiring separate vapor
~ ¦ evacuation equipment such as ~an 100 shown in Fig. 2.
221
23
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26
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