Note: Descriptions are shown in the official language in which they were submitted.
5130
~395~ :
Backqround of tha Invention
1. Field of the Invention
This invention relates to photography and, more par-
ticularly, to improved apparatus for distributing a proces-
sing fluid in a layer between a pair of superposed sheet
elements.
2. Description of the Prior Art
In a process for producing a visible image from an
exposed self-developing film unit~ a fluid processing reagent
is spread in a uniformly thin layar between a pair of super-
posed photographic sheet elements forming part of the film ;
unit. The processing fluid is stored in a pressure ruptur-
able container forming an integral part of the film unit,
located adjacent a leading edge of the exposed area, and
adapted to release its contents between the sheet elements
when under the influence of an applied hydraulic pressure.
Such film units, as for example those described in consider-
able detail in U.S. Patents ~o. 2,543,181 and 3,415,644, nor-
mally contain all the photographic components necessary to
carry out this process.
The physical arrangement of hase components define ~ -
an especially designed film unit structure that cooperates
with a processing fluid apparatus to determine the distribu-
tion of the processing fluid thickness over the exposed area
of the film unit. A processing fluid apparatus is likewise
especially structured to complement the structure of the
film unit so that, when both are brought into contact with
each other, their interactions assure a proper processing -~
fluid distribution.
These interactions may be functionally categorized
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into two steps. The first step involves creating a pressure
within the fluid container sufficient to rupture it and re-
lease its fluid contents. The second step is that of spread-
ing the fluid over the exposed area of the film unit as the
film unit is advanced through the processing apparatus. Dur-
ing both of these stPps~ complex f~uid flow phenomena occur
that ultimately determine the quality of the final visible
image. Because the flow phenomena is so complex, experience
has shown that dependable practical results can be achieved
only through running carefully controlled experiments. Re-
sults of these experiments describe the fundamental flow fea-
- tures in terms of the interaction of the film unit and pro-
cessing apparatus variables with precision sufficient to per-
mit alternate choices of design solutions that eliminate pro-
blem areas associated with the process.
These problem areas might for example be: 1) poor
initial distribution of fluid within its container; 2) uneven
release of tha fluid from its container; 3) an undesirable
modification of the distribution of the fluid as it is spread
between the sheet elements; or 4) an excess ~nount of fluid
after the processing operation has been completed. The first
three problem areas could oauRe inadequate fluid coverage
over the exposed area of ~he film unit and the last one, if
nct properly solved, could allow the excess ~luid, which is
caustic~ to come into contact with the camera user or other
components of the camera system.
The prior art describes numsrous solu~ions to such
problems, as for example, a flow retarding apparatus described
in U. S. Patent ~o. 2,991,703 or a film unit having a fluid
' container with integrated flow director~ described in U~ S~
: ~
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~0395~
Patent No. 3~342J600~ or a film assemblage with tapered spacing strips describ~
ed in United States Patent No. 3,761,268. These disclosures of prior art re-
present a particular choice of design controllable parameters which influence
the fluid thickness distribution and aid in its confinement to the film unit.
It is fslt, however, that the present invention provides an alternate selec-
tion which recognizes the teaching of the prior art but, for reasons which
will be apparent, has inherent advantages over it.
Therefore, an object of this invention is to provide improved
photographic apparatus for spreading a processing fluid between a pair of -
sheet elements.
Another object of this invention is to provide fluid processing
- apparatus that will simplify the structure of the film unit and will itself
have a simplified structure.
Another object of this invention is to provide apparatus of the
type indicated wherein fluid distribution and flow control are facilitated ;
by specially configured pressure applying members.
Yet another object of this invention is to provide apparatus of
the type indicated wherein the initial distribution of the fluid within its
container is controlled by specially configured pressure applying members.
Other objects of the invention will in part be obvious and will
in part appear hereinafter.
According to the presen~ invention, there is provided photographic
apparatus including means for spreading a processing fluid in a layer between
a pair of sheet elements, said spreading means comprising: a first member
having a first sheet-contacting surface; and a second member mounted in juxta- -
posed relation to said first member and adapted to define a pressure generat-
ing gap therewith through which the sheet elements are adapted to be advanced
during spreading of the processing fluid, said second member including a gener- `
ally rigid support member having superimposed thereon a layer of resilient
`~ 30 material having a longitudinally extending continuously varying thickness
that cooperates with said support member to provide a second sheet-contacting
surface having longitudinally extending variable deformation capability.
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103~S48
In its preferred embodiment the invention is depicted as an
apparatus for spreading a processing flui.d in a layer between a pair of
photographic sheet elements at least one of which forms part of a film unit
of the self-developing type.
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The apparatus consists of a pair of juxtaposed rollers
rotatably mounted between a pair of spaced apart vertical sec-
~ tions of a "U"-shaped support bracket. The vertical sections
; include, respectively, elongated slots which facilitate the
relative translatory displacement of one of the rollers with
respect to the other. Resiliently urging the rollers toward
one another is a torsion spring mounted on ths base of the
support bracket and having end portions which cradle the jour-
nals of the roller permitted to displace wit~in the elongated
slots.
Spaced apart annular collars located opposite ad~acent
ends of one of the rollers extend to contact the surface of ;
the other roller thereby separating the rollers by a minimum
spacing determined by the size of the extended collars. This
spacing ~acilitates the introduction of the film unit between
the rollers prior to its being processed. One o the rollers
is rigid having a substantially cylindrical configuration.
The other roller consists of a structure which includes a
; rigid support member having a curved exterior configuration,
convex in shape~ over which lies a layer of resilient material --
of a suitable elastomer such as urethane. The resilient layer
has an interior shape similar in shape to the exterior shape -
of the support member and an exterior sheet-contacting surface
; whose shape is substantially cylindrical. Because of its
structure, the layer of material overlying ~he support member
provides the structured roller with a sheet-contacting surface
of variable deformation characteristics across it~ length
since the thickness of the resilient layer varies as a func-
tion of the exterior shape of the support member. By care-
fully selecting the deformation characteristlcs of this sheet-
.
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3954~
contacting surface and recognizing its sensitivity to hydrau-
lic pressures induced in the processing fluid during spread-
ing of the fluid between the sheet elements, it is possible
to provide simplified apparatus and film unit structure which
results in an economical solution to the problems of fluid
flow control and film unit size.
In addition this selectively deformable surface can
be used as a means for controlling the initial distribution
of the processing fluid within its storage container which~
incidentally, usually forms part of the film unit.
j- one of the rollers also includes a gear which when en-
gaged with suitable drive means permits the roller to be ro-
tated such that it provides a traction force which can advance
the film unit through the apparatus. The traction forco in
this respect would obviously depend on the friction cha~ac-
teristics between contacting surfaces of the sheet elements
and the apparatus. There~ore, the coefficient of friciio~
of the resilient layer can aid considerably if the apparatus
is utilized with a system embracing automatic film-advancing
means.
Brief Description of the Drawinqs
The novel features that are considered characteristic
of the invention are ~et forth with particularity in the ap-
pended claims. The invention~ however, both as to its organi-
zation and its method of operation, together with additional
ob~ects and advantages thereo~ will best be understood from
the following description when read in connection with the
; accompanying drawings wherein like numbers have been employed
in the different figures to denote the same parts and wherein:
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~3395~
Figure 1 is a diagrammatic perspective viewJ
with partially broken away parts, of a self-developing
film unit for use with the invention;
Fig. 2 is a top view of the film unit of
Figure 1, with parts broken away, illustrating problem
fluid flow patterns;
Fig. 3 is a schematic cross-sectional view of
film unit and a pair of juxtaposed rigid rollers
illustrating the r~lationship between the film unit and
rollers which causes the fluid flow patterns shown in
Fig. 2;
Fig. 4 is a view similar to that of Fig. 2
illustrating fluid flow patterns possible with the
invention;
Fig. 5 is a view similar to that of Fig. 3
illustrating the relation of the rollers of the invention
with a film unit which causes the improved fluid flow
patterns shown in Fig. 4;
Fig. 6 is a diagrammatic perspective view of
the fluid processing apparatus of the invention; and
; Fig. 7 is a diagrammatic perspective view of
an alternative embodiment of the inventionO
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Detailed Description of the Invention
In the photographic sciences, a latent image
is defined as being an invisible record of the position
and intensity of radiation incident on a photosensitive
emulsion. In order to transform a latent image to a
visible picture, it is necessary to subject the exposed
photosensitive emulsion to a photographic process con-
sisting of a series of chemical and mechanical operations.
Such process~s may be classified using various criteria
suitable for particular purposes. One classification
scheme differentiates processes on the basis of the time
the process requires to produce a useable picture. When
compared with conventional processing means as a standard,
a rapid process would be one requiring much less time to
render the latent image visible. One rapid process very
familiar in the art is known as diffusion transfer. The
present invention relates to this process and particularly
to the problems and na~ure of apparatus associa ed with
the mechanical processing aspects. Specifical;y,the
mechanical aspect of interest is that of spreading a
processi~g fluid in a layer betwPen a pair of superposed
photographic sheet elements a~ leas~ one of which forms
- part of a self-developing film unit that has been exposed
to actinic radiation~
~5 The processing fluid in this case chemically
facilitates the forma~ion of the visible image on an image-
receiving sheet by first developing the latent image and
then, as a function of development~ forms and transfers
image forming components from the developed emulsion to
the image-receiving sheet. The quality of the final image
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103954~3
critically depends on the uniformity of the processing
fluid thickness between the sheet elements over an
area corresponding to the exposure. The relationship
between the film unit and the apparatus for spreading
the fluid between the sheets detexmines the fluid
thickness uniformity. In order to assure that the
requirements for a high quality photograph are fully met,
it is obvious that these relationships be thoroughly
understood, or alternatively/ the outcome be rendered
deterministic by appropriate systematic means.
The complexity alluded to above is rooted in
the fact that the physical relationships between the film
unit and the apparatus for mechanically spreading the
processing fluid are difficult, if not impossible to
analyze using purely ma~hematical methods. Experimental
methods, by far, have proven to be the most succassful
way of dealing with the problems of designing processing
apparatus. Because the physical relationships involved
can be characterized as being essentially complex fluid
flow phenomena, the experimental method usually chosen
is dimensional analysis. This method has proven quite
successful in the organization, correlation, and inter-
pretation of experimental data.
Briefly, dimensional analysis is a pseudo
mathematical method employed in checking equations, changing
units, determining a convenient arrangement of Yariables
: of a physical relation, and planning systematic experiments.
Dimensional analysis, then, results in a sound, orderly
arrangement of the variable physical quantities involved
in a problem. Reference to experimental data must be
made in order to obtain the necessary numerical values of
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~0~954~3
the variables that define a solution. It should be
appreciated that a study of dimensions by itself does
not yield any information about the physical phenomena
or the functional relation between the variables involved.
- 5 It does, however, frequently aid in making an eaisier and
more convenient description of the phenomena.
The first step in treating a problem using
this method is to list all the variables involved. The
selection Lypically comes from experience or judgment.
The next step, the analysis, is made following an
orderly experimental plan. The final resolution of the
problem based on tha selected variable arrangement is no
more accurate or complete *han the original choice of
variables~ Consequently, any incomplete or inappropriate
choice o original variables will not result in a reso-
lu~tion of the problem but, as pointed out, generally
results in sufficient insight into the physical
functional relationships involved which does permit
resolution through proper itera~ive corrections. ~he
present invention was conc~ived using this technique.
It, in factr is based on the recognition of aertain
features of the fundamental flow patterns derived from
prior experi~ents using apparatus not incorporating its
novel features. In order to~fully appreciate what these
features are and how they solve t,he problems involved, it
will be necessary to be acquainted with the general design
criteria for such fluid spreading apparatus, prior
experimental apparatus structure illustrating its fluid
flow patterns, and the events tha~ occur during the
mechanical stages of the photographic processing of the
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~3954~
exposed emulsion.
In order of sequence, the last will be
discussed first by illustrating the structure of a typical
film unit and then describing how it is treated after
it is exposed.
Reference is now made to Fig. 1 wherein is
illustrated a self-developing film unit 10 of the type '
disclosed in considerable detail in U. S. Patent No.
3,415,644 by ~dwin H. Land issued December 10, 1968. It
is reerred to here to illustrate the xelevent mechanical , ;'
features of such film units and is not intended, in any
.
'' sense, to restrict the applicability of the present
invention. The film unit 10 has a generally rectangular
, photosensitive image-recording sheet element 12 wherein
a latent image can be recorded. Located in superposed
face to face relation with sheet element 12 is a second,
slightly longer, image-receiving sheet element 14. Sheet ~'
element 14 is transparent and adapted to transmit actinic
radiation to sheet element 12 during exposure. Its ,
increased length defines an extended portion 20 under
'~ which is located a pressure-rupturable fluid container 18
, adapted to release its fluid contents 19 (not shown in this
figure~ between the sheet elements.
A generally framelike element 16 serves multiple
functions. To begin with element 16 is a generally
rectangular opaque thin sheet having dimensions slightly
' greater than those of sheet element 14 and having portions
., :
defining a generally rectangular aperture'22 whose
dimensions are slightly smaller than those of sheet
element 12. ~lemcnt 16 is superimposed on the s,urface of
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~39~
sheet element 14 so that aperture 22 overlies sheet
element 12 to define the limits of the area of that
element which can be subjected to actinic radiation.
After it is superimposed on sheet element 14,those portions
of ele~ent 16 that extend beyond the laterial margins of
sheet element 14 are wrapped around the lateral edges
of the sheets and fluid container I8 and secured to the
surfaces of sheet element 12 and fluid container 18 by
suitable adhesive means to form a single lntegrated
structural unit possessing certain important physical
features.
The first impor~ant feature is related to
the integral nature o fi'm unit 10 thus constructed.
When the fluid contents 19 are released to be spread
between the sheet elements 12 and 14, it exists as an
elongated mass adjacent a leading edge 26 of the exposure
area and extending laterally to longitudinal edges 28 of
the sheet elements 12 and 14. Those portions of element
16 overlapping longitudinal edges 28 function to confine
fluid 19 within film unit 10 while the fluid is
progressively spread over the exposed area as film unit 10
is advanced longitudinally from its leading edge 30 to its
trailing edge 32 through suitable processing apparatus.
In like manner, any excess fluid remaining after the
advance~ent is complete will be confined to ~he film unit ;
10 in a region 34 located adjacent trailing edge 32 and
which underlies the inward extension of element 16 on the
surface of sheet element 14.
The other important features have to do with
the mechanical structure that exists where element 16
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:~39~
overlaps longitudinal edges 28. The structure here
defines spaced apart longitudinal edge portions 36
extending lengthwise rom leading edge 30 to trailing
edge 32 which provide a bearing surface upon which
suitable pressure applying members may ride retaining
longitudinal edges 28 of sheet elements 12 and 14 in
face to face contact while at the same time providing a
- means for separating such pressure members by a distance
prescribed by the thicknesses of the sheet elements plus
twice the thickness of element 16. It can be appreciated
that the spacing between such pressure members will allow~
sheet elements 12 and 14 to separate when fluid 19 is
introduced between them. This separation will occur
throughout the exposed area intermediate longitudinal
edge portion 36.
Another important feature relevant to the
operation of the invention relates to the mechanical
properties of sheet elements 12 and 14. Aside from their
photographic proper~ies, they are composed o~ material
which allows them to deform undsr pressure.~ This means
- that if sufficient hydraulic pre~sure exists in the fluid
as it is spread bet~een the sheets, they will tend to take
on a shape which conforms to whatever stxucture resists
their separating. The implication of this property will
become clear in a later discussion.
Subsequent to the exposure of film unit 10, it
is photographically processed by advancing it through a
suitable mechanical apparatus which first serves to rupture
fluid contrainer 18 releasing its fluid content 19 and
then to progressively spread the fluid between sheet
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3l039548
elements 12 and 14 as further advancement occurs. In
this respect advancement of film unit lO may be done
manually or by suitable automatic means such as a
motoriæed traction drive roller. Thus it is seen that
the fluid processing apparatus performs two distinct
functions.
The structure of such processing apparatus
- can take on any suitable configuration but generally
comprises several fundamental structural elements.
- lO Namely, these elements are generally a pair of elongated
juxtaposed pressure applying members, usually rigid
rollers, biased towards one another by resilient means.
The rollers are usually initially separated by pregap
means to facilitate introduction of the film unit between ~;
them and, in addition, becau~e of the biasing means, are
adapted to define a pressure generating gap through which
the film unit is adapted to be advanced. As an exposed
film unit, such as film unit lO, is ad~anced between such
rollers the force urging the rollers together induces -
sufficient pressure in the fluid container 18 to rupture ~;
it and release its fluid contents 19 in an eLongated mass
adjacent leading edge 26 of the exposure area. The mass
of fluid is then moved lengthwise across the exposure area
as the film unit is advanced through the pressure
generating gap formed by such rollers. Several interesting
flow patterns emerge from experiments conducted using an
apparatus like the one just described, i.e., one having
only the fundamen al structural elements. These flow
patterns, which are illustrated in Fig~ 2, considered with
other design requirements for self-developing film units,
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~039s~ `
will demonstrate the necessity for alternate design ~ -
solu-tions such as the one offered in the present invention.
To begin with the important variables in a
dimensional analysis of the fundamental apparatus includes
both those associated with the film unit and apparatus.
Briefly these would be: the force urging the rollers
toward one another, the rigidity of the rollers, the gap
separating the rollers caused by longitudinal edge
portions 36 of the film unit, the viscosity of the fluid,
the rate of advancement of the film unit through the
apparatus, and the flexibility of the film u~it sheet
elements. ~he performance requirement, it will be recalled,
- is a uniformly thick fluid layer between the sheet
elements over the exposure area. In addition, the film
unit size is to be kept at an absolute minimum and the
.
fluid confined inside it because of the caustic nature of -
the fluid.
Experimental data has shown that manipulation
of the sizes of the variables pointed out permits a -
certain degree of control of the flow pattern of the fluid.
However, without the addition of supplement~y flow control
devices in the film unit or the fundamental apparatus, the
flow pattern remains substantially the same~ Looking at
- Fig. 2 the flow pattern is seen at three di~fexent
locations along the exposure area. It is first shown
adjacent a broken front seal 38 of fluid container 18 as
a mass distributed in a curved pattern with a high con-
centration of fluid in the medial section o~ the exposure
area and tapering off laterally to lower mass concentration
towards the longitudinal edges ~8. At about half the length
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- of the exposure area the pattern becomes less favorably
distributed. Toward the end of the exposure area the
pattern is grossly changed from its original shape.
In terms of the design criteria,flow patterns
S like this are intolerable because they tend to require
excess fluid in the container to assure complete coverage
- of the exposure area and therefore also necessitate a
"trap" area in the film unit to retain the excess fluid.
This increases the probability of leaking fluid from the
film unit and requires a larger film unit. This means
increased cost and size of the film unit. `
There are a variety of explanations for the
existence of this characteristic flow pattern and a
variety of solutions in the prior art to cope with it~ ~
Some explanations, for example, are poor initlal dis- ~;
tribution of the fluid within its container and uneven
rupture of front seal 38 causing initially curved patterns.
By looking at Fig. 3, one can imagine other explanations
e.g., bending of rollers 40 and ~2 caused by high pressure -
generated in the fluid mass 19 or increased separation of
the rollers because the pressure generated during processing `
exceeds the forces urging them toward one another, thus
causing not only poor coverage but also nonuniform thick- -
ness of the fluid layer.
The solutions proposed in the prior art
compensate for the characteristic flow pattern in two ~:~
general ways. The first method takes notice o the
possibility of the poor initial distribution of fluid
within container 18 and the problem associated wi~h uneven
breakage of front seal 38. The approach essentially taken
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~)39541~
here is to provide partitions in container 18 which act
as chambers for containing certain predetermined amounts
of fluid in particular locations in the container thereby
permitting the mass of fluid from each chamber to be
distributed ~ore evenly when each chamber seal is
ruptured. In addition these chambers are ~eometrically
designed to act as flow directors further controlling
initial distribution of fluid immediately after it exits
the container 18. This obviously complicates the design
- 10 and manufacture of container 18 with the attendant incraased
cost in so doing.
Another approach is to provide a dual set of
rollers spaced apart lengthwise with the forward set having
low biasing forces insufficient to rupture container 18 ~-
and the rearward set performing the actual container seal~
breaking function. This permits the forward set to act
as a fluid retarder which delays the forward motion of the
fluid in the medial section of the exposure~area. It is
clear that this approach, while successful,also increases
size and cost because of the necessity of additional parts
to the apparatus.
Yet another approach is to modify film unit 10
by providing variable thick~ess longitudinal edge portions
36 that control the fluid thickness layer. This has the
drawback of complicating the manufacture and control of
the film unlt because of the requirement of iccurate placing
of the spacing means.
The present invention arose from'a recognition
: of one of the functional relationships characteristic of
the flow phenomena. Specifically, the pressures induced
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103'g5i~8
in the fluid during the spreading stage are indeed
substantial and vary as a function of advancement speed~ -
In fact the characteristic flow pattern very much appears
to be not unlike the traditional parabolic velocity
distribution for the laminar ~low of a viscoUs fluid in a
closed pipe. This being the case the pressure may be
used in cooperation with a selectively pressure deformable
surface on at least one of the pressure applying members
whose characteristics would compensate for the uneven
pressure distribution exemplified by the characteristic
- flow pattern.
As an additional benefit such a selectively `~
deformable surface may additionally controil the initial
distribution of the fluid within its container just prior
to the release of the fluid. This one change based on
recognizing a fundamental property of the dynamic inter-
action of the film unit and spreading apparatus thus permits
a simplification of both the ilm unit and apparatus
while at the same time satisfies all the design require-
ments while permittinq a reduction in cost.
Fig. 5 shows schematically two rollers 44and 46. It will be noticed that roller 44 comprises a rigid
- support member 45 covered with a resilient layer 48 of
material which deforms under pressure~ The altered flow
patterns possible with this system are illustrated in
Fig. 4 which should be compared with the fl~w patterns in
Fig. 2. It is evident that the initial distributions as
well as later modifications are much more co~patible with
the basic design requirements of complete uniform coverage
with minimal film unit size.
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The concept of this invention assumes that
resilient biasing means urging the pressure applying
members toward one another provide forces sufficient to
keep the members and the longitudinal edges 28 of the sheet
ele~ents 12 and 14 in contact while permitting the
surface of one of the pressure applying members to deform
in a predeterm1ned manner to control the fluid flow by
initially distributing the fluid mass properly and
retaining the initial distribution pattern throughout
; 10 spreading.
Preferred Embodiment
Fig. 6 illustrates a preferred embodiment of
a fluid processing apparatus 43 incorporating the
features of the invention. It consîsts of a rigid "U"-
shaped support bracket 50 in which are rotatably mounted
a pair of juxtaposed pressure applying members 52 and 54.
Both members are shown as rollers with member 52 being
adapted to be displaced with respect to member 54 as
film unit 10 is advanced between them. In this respect ~ -
bracket 50 has portions defining a pair of elongated
slo~s 56 located in ~ertical tab sections 57 of bracket
50 which facilitate the relati~e motion of member 52
with respeet to ~ember 54 by functioning as linear guides
to direct transatory displacement.
- 25 Member 52 is resiliently urged toward member
54 by a torsiOn like spring 58 which is mounted to base
section 60 of bracket 50 with end portions 62 that cradle
journals 61 of member 52,
Member 54 is a roller structure consisting of
a rigid support member 64 which has a substantially convex
-18~
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- shape. Located in overlying relation to support member
64 is a resilient layer 66 of a suitable elastomeric
material such as urethane. Layer 66 has an internal
shape similar to the external configuration of support
member 64 and an external sheet contacting surface 68
which is substantially cylindrical. The thickness of
layer 66 is therefore variable thus per-
mitting variable deformation capability acxoss the
length of member 54.
Member 54 also includes a pair of spaced
apart annular collars 70 located adjacent opposite its
ends. These collars extend from member 54 to contact
the surface of member 52 and thereby provid~ a pre-
determined spacing between these members which facilitates
lS the introduction of film unit lO therebetween.
Additionally member 54 has at least one
extended journal 72 upon which is mounted a~gear 74
adapted to engage a motorized system (not shown) to impart
; rotating motion to member 54. Inasmuch as the material
of layer 66 may-have high friction charac~eristics, it in
cooperation with the rotatory motion of member 54 pro~ide
a traction force for advancing film unit lO through the
apparatus 43. However the invention may be practiced without
this feature thus permitting its use with film units like,
for example, the one described in U. S. Patent No. 3,765,887
which would allow the film unit to be manually advanced.
Another embodiment of the invention is
illustrated in Fig. 7. The apparatus shown here is
functionally equivalent to the previously de~cribed
embodiment except that the pressure applying members 76
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~L~;395~t3
and 78 are elongated bar structures which are not
rotatably mounted. It is evident with this embodiment
that the resilient layer 80 of memher 76 would have to
be a low friction surface for proper functioning in
terms of ease of film advancement. In other respects
this embodiment is similar to that shown in Fig. 6,
namely consisting of a support bracket 82, biasing
spring 84, elongated guide slot 86, and rigid support
member 88 of member 76.
Those familiar with the photographic arts
will readily appreciate the subtlety of th_s inventive
concept and why it achieves the simplification of both
apparatus and film unit structure while minimizing
costs.
This invention may be practiced or embodied
in still other ways without departing from the spirit or
essential character thereof. The embodiments described
herein are therefore illustrative and not restrictive,
the scope of the invention being indicated by the
appended clalms and all variations which come within
the meaning of the claims are intended to be embraced
therein.
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