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| United States Patent |
3,552,292 |
|
Gold
|
January 5, 1971
|
PHOTOGRAPHIC PROCESSING APPARATUS
Abstract
Apparatus for applying an accurately predetermined quantity of a liquid
processing agent uniformly to successive exposed areas of photosensitive
sheet material. The apparatus includes an applicator roll with a grooved
surface rotated in a liquid-containing well and the sheet material is
moved upwardly at an angle in contact with the oppositely moving surface
of the roll to form a meniscus of the liquid between the roll surface and
the sheet material. One side of the well is higher than the other and
includes a cylindrical surface cooperating with the roll surface to form a
throat for controlling the quantity of liquid carried upwardly by the roll
through the throat into contact with the sheet.
| Inventors: |
Gold; Nicholas (Arlington, MA) |
| Assignee: |
Polaroid Corporation
(Cambridge,
MA)
|
| Appl. No.:
|
04/723,040 |
| Filed:
|
April 22, 1968 |
| Current U.S. Class: |
118/246 ; 118/258; 396/606 |
| Current International Class: |
G03D 5/06 (20060101); G03D 5/00 (20060101); G03d 005/06 () |
| Field of Search: |
95/89,94 118/258,246
|
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. Apparatus for applying an accurately predetermined quantity of a liquid reagent uniformly to a succession of areas of sheet material comprising, in combination:
body means defining a well for containing liquid;
a cylindrical roll mounted for rotation about its axis within said well;
means for introducing a liquid reagent into said well beneath said roll;
said well including a wall on one side extending from beneath said roll upwardly to approximately a plane through said axis of said roll;
said wall having a cylindrical surface substantially parallel with and spaced from the peripheral surface of said roll, said surface of said wall and said roll cooperating to define a throat within which liquid within said well is carried
upwardly to form a meniscus between said wall and said roll when said surface of the latter is rotated upwardly with respect to said wall; and
a cover mounted on said body means for cooperating therewith to define a container enclosing said roll and liquid within said well, said cover including guide portions and being mounted for movement relative to said body means between a closed
position in which said guide portions engage said support surface to close said container and an open position at which said guide portions are spaced from said support surfaces to provide passages adjacent said sides of said well for guiding sheet
material between said body means and said cover across said well in contact with said roll.
2. Apparatus as defined in claim 1 including guide means mounted on said body means and located between said roll and said cover for guiding sheet material entering through one of said passages around a portion of said periphery of said roll
through said passage on the opposite side of said well.
Description
The present invention is concerned with a liquid applicator especially designed to apply an accurately predetermined quantity of a
processing liquid to sheet material and is particularly adapted for incorporation in photographic apparatus such as document copiers wherein an aqueous processing liquid is applied to successive exposed areas of photosensitive sheet material to form
visible images therein. In document copying apparatus of this type successive areas of sheet material including, for example, a layer containing a photosensitive image-recording medium such as silver-halide, are exposed and then advanced as individual
sheets through the applicator which is required to apply a predetermined quantity of a processing liquid uniformly to the entire exposed area or sheet while the latter is moved at a comparatively rapid linear rate relative to the applicator. In typical
apparatus of this type, the exposed area or sheet is rectangular and measures 8 1/2 .times. 11 inches and the applicator is required to apply the liquid commencing with leading edge of the sheet so as to coat the entire sheet completely and uniformly
with a very precisely metered quantity of the liquid.
In a typical photographic process adapted to be performed by the applicator apparatus of the invention, a composite photosensitive sheet including a support such as paper and at least a layer containing a photosensitive material such as
silver-halide, a white opacifying agent and an agent providing a silver precipitating environment, is exposed to produce a latent image in the sheet and is thereafter treated with an aqueous alkaline liquid processing solution to produce a visible image
by a diffusion transfer reversal process. The processing solution may include, among other constituents, a silver-halide developer and a silver-halide complexing agent which may be present initially in the solution applied to the sheet or may be
included in a dry form in the sheet itself in which case the processing liquid will be so constituted to activate the agents in the sheet and will include water and an alkali. The processing liquid is applied to one side of the sheet and is immediately
absorbed thereby initiating processing in which exposed silver-halide is developed and an imagewise distribution of diffusible image-forming substances such as a soluble silver complex, is formed from unexposed silver-halide and is transferred by
diffusion to a layer or a strata providing a receptive environment for the image-forming substances, for example, a silver precipitating environment in which silver is precipitated from the complex to form a positive image. For details of process of
this type and materials employed therein reference may be had to the copending U.S. Pat. application of Edwin H. Land et al. Ser. No. 519,884, filed Jan. 11, 1966, now U.S. Pat. No. 3,507,650 .
Image-forming processes of the type described occur very rapidly, e.g. in a few seconds, so that it will be apparent that in a process of the foregoing type, a number of different but closely related reactions occur at the same or nearly the same
time; and that the quantity of liquid applied to the sheet material and available for processing is critical, insufficient liquid may upset the rate relationships between the various processes and/or prevent the image-forming process from continuing to
completion; while excess processing liquid may also have a disturbing effect upon the process relationships and provides a reservoir in the sheet of excess processing liquid which may contribute to undesirable diffusion of the image-forming substances or
cause the transfer image to be "washed" away and which must be removed from the sheet material constituting the finished print or copy. Not only is the quantity of the liquid applied critical to proper image-formation, but it is relatively small and it
must be applied uniformly to only one side of the sheet while the sheet is in motion. For example, in a typical process such as described in the aforementioned Land et al. application, approximately 0.7 to 0.8 cc of the processing liquid is all that is
required to be applied to an area of the sheet material measuring 81/2 .times. 11 inches, or enough to form a layer on this area .0006 inch deep while the sheet is moved relative to the processor at linear speeds ranging from 3 to 10 inches per second.
Objects of the invention are: to provide photographic processing apparatus of the type described adapted to apply rapidly and uniformly, accurately predetermined and relatively small quantities of a nonviscous photographic processing liquid to
one side of each of successive areas of photosensitive sheet material; to provide liquid applicator apparatus of the type described including a roll rotated in a liquid-containing well having a wall cooperating with the roll to control the quantity of
liquid applied to the sheet material; and to provide liquid applicator apparatus as described which is dependable and reliable in its operation while having a simple and inexpensive instruction.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the apparatus possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be
indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:
FIG. 1 is a perspective view, partially in section with parts broken away, showing a liquid applicator embodying the invention;
FIG. 2 is a sectional view through the applicator of FIG. 1;
FIG. 3 is an enlarged, fragmentary, perspective view of the roller of the applicator; and
FIG. 4 is an enlarged, fragmentary, sectional view illustrating the operation of the applicator.
The liquid applicator of the invention is specially designed for incorporation in document copying apparatus adapted to be employed with an
integral image-recording and image-receiving sheet material and to perform a process of the type described in the aforementioned Land et al. patent application. The sheet material comprises a paper support carrying on one side at least a layer including
a stratum containing a light-sensitive silver-halide emulsion and an outer stratum comprising a translucent material such as finely divided titanium dioxide dispersed in a suitable permeable colloidal carrier on matrix such as gelatin which is permeable
to an aqueous processing liquid. The translucent pigment may be incorporated in the stratum containing the light-sensitive material and/or may comprise a separate outer stratum which also contains silver precipitating nuclei providing a silver-receptive
stratum. The outer stratum is sufficiently light transmitting to permit exposure of the light-sensitive material there beneath while at the same time being sufficiently opaque to provide a requisite background for a positive silver image transferred
thereto by diffusion and to mask a negative image formed thereunder. Processing of this exposed integral image-recording and image-receiving sheet is accomplished with an aqueous alkaline liquid including a silver-halide developer such as
phynelhydroquinone and a silver-halide complexing agent such as sodium thiosulfate, which is applied to the coated side of the sheet opposite the support so as to impregnate the light-sensitive stratum with sufficient processing liquid to produce a
positive silver transfer image on the surface of the translucent layer. In a preferred process the silver-halide developer is incorporated, in a dry or crystalline form, in the strata containing the silver-halide emulsion, and the processing liquid
constitutes an activator solution, the principal ingredients of which are water, alkali, and the silver-halide complexing agent. This latter composition is preferred to including the developer in the processing liquid because it reduces the problems
attendant to storing the liquid so as to prevent oxidation of the developer. However, the liquid is extremely alkaline having a pH of the order of 13 to 14 so that the problems of storing, handling, and applying a highly caustic and corrosive liquid
remain.
Reference is now made to FIGS. 1 through 3 of the drawings wherein there is illustrated a liquid applicator designated 10 including a body 12, a roll 14 and a cover 16. Body 10 is formed with an elongated well 18 extending substantially from end
to end of the body and having a length at least equal to the width of the sheet material to be coated. Roll 14 is cylindrical, has a length at least equal to the width of the area of the sheet material to be coated and is mounted for rotation about its
axis within the well. Body 12 includes end walls 20 and roll 14 is mounted for rotation on shafts 22 journaled in end walls 20, the latter preferably being provided with liquidtight seals around shafts 22 to prevent liquid within the well from leaking
around the shafts. The applicator is designed to be employed while oriented so that the axis of roll 14 lies in a substantially horizontal plane and will be described as being so oriented.
Body 12 includes a longitudinal section 24 extending upwardly above roll 14 and having an inner cylindrical surface 26 defining one sidewall of well 18 extending from beneath roll 14 upwardly parallel with the peripheral surface of the roll to a
position at least above a horizontal plane through the axis of the roll and preferably to a position as shown above the roll axis. Inner surface 26 is bounded by a lower edge located beneath the roll approximately in line with the roll axis and is
spaced from the roll surface so as to cooperate therewith to define a narrow throat 28 commencing at the lowest part of the roll surface and adapted to perform a function which will be described in greater detail hereinafter. Body 12 includes another
side section 28 defining the opposite side of well 18 which is also provided with a sump 30 for collecting any residue of materials which may wash off the sheet material during application of liquid thereto.
The upper surface of side sections 24 and 28 are adapted to provide means for supporting and guiding sheet material to be coated upwardly and at an angle (from right to left viewing FIGS. 2 and 4) across and in contact with a descending portion
of the roll surface. These support surfaces designated 32 and 34 are located in the same plane disposed at approximately a 45.degree. angle with respect to the horizontal when the applicator is operatively positioned, i.e., with the axis of roll 14
lying in a horizontal plane, and the peripheral surface of roll 14 projects from well 18 beyond the plane of surfaces 32 and 34 so as to contact a sheet guided along and supported on the support surface.
Cover 16 is pivotally mounted at its ends on shafts 36 engaged in openings 38 in extensions 40 of sidewalls 20 of body 12 and is positioned in covering relation to the roll mounted in well 18. Cover 16 includes a longitudinal recess 42
approximately equal in length to the length of the well and upper and lower edge sections 44 and 46 having surfaces adapted to engage support surfaces 32 and 34, respectively, in the closed position of the cover. Cover 16 is pivotable about shafts 36
between the closed position shown in FIGS. 1 and 2 in which the lower surfaces of edge sections 44 and 46 are engaged with support surfaces 32 and 34, and an open position shown in broken lines in FIG. 2 in which the edge sections of the cover are spaced
from the support surfaces to provide entrance and exit passages for sheet material. At least one of shafts 36 is keyed to the cover to provide means for pivoting the cover between the open and closed positions thereof. Support surface 34 is curved and
cooperates with the lower or facing surfaces of section 46, when the cover is in the open position, to define a convergent passage for guiding the leading edge of a sheet upwardly into and through the applicator toward the passage defined by support
surface 32 and the facing surface of edge section 94.
The applicator is designed to process a succession of sheets, each advanced leading edge foremost into the applicator through the passage defined by support surface 34 and edge section 46. A guide plate 48 is provided mounted within the
applicator between roll 14 and cover 16 for guiding the leading end of the sheet into the passage between support surface 32 and edge section 44 and supporting the sheet against the roll along a line extending full width of the sheet during movement of
the sheet through the applicator.
In the operation of the applicator apparatus the processing liquid is introduced into well 18 to maintain the liquid at a static level slightly above the lowest part of the peripheral surface of the roll. A conduit 50 leading from the exterior
of the applicator through body 12 into the sump 30 is provided as means for introducing liquid into the well. Roll 14 is rotated in a clockwise direction (viewing FIGS. 2 and 4) so as to entrain and carry the liquid upwardly within the well between the
roll and inner cylindrical surface 26. During rotation of the roll, a sheet designated 52 is moved through the applicator from left to right upwardly substantially tangent to a descending portion of the roll surface so that liquid entrained by the roll
forms a meniscus, designated 54, between the surface of the sheet and the surface of the roll. As the roll surface and sheet continue to move in opposite directions, this meniscus 54 is sheared with the sheet carrying away on its surface a predetermined
quantity of the processing liquid. The presence of the meniscus which extends from edge to edge of the sheet insures that liquid will be applied to all portions of the sheet and that there will be no gaps in the liquid coating.
In order to insure formation of meniscus 54 and, of equal importance, application of a predetermined quantity of the liquid to the sheet commencing at the leading edge of the sheet, the surface of roll 14 is textured so as to increase the
quantity of liquid entrained by the roll during rotation thereof. As shown in FIG. 3, this texturing takes the form of circumferential grooves 56 having a generally U-shaped cross section and dimensioned to function in the nature of capillaries for
entraining additional liquid. In a typical applicator structure comprising a one inch diameter roll, satisfactory liquid application is achieved with grooves formed as a multiple lead, 10-pitch thread with a depth of the order of .008 to .010 inch, a
width of .005 to .006 inch, and a land width approximately three times the groove width. The roll is immersed to a depth of approximately three-sixteenths inch in the liquid within the well and is rotated at a speed such that the surface velocity of the
roll is 2 inches per second. Operating with this particular structure and under the foregoing conditions, a layer of liquid approximately .0006 inch deep can be applied to the surface of a sheet moved through the applicator at the rate of 3 inches per
second.
As previously noted, cylindrical surface 26 is spaced from and located in parallel relation with the outer peripheral surface of roll 14 and cooperates therewith to provide a throat 27 leading from beneath the roll upwardly adjacent the ascending
side of the roll. During rotation of roll 14, the liquid within the well tends to rise within the throat which functions to limit the level of the liquid and the quantity thereof which is carried on the roll surface beyond the throat and into contact
with the sheet. It has been found that the quantity of liquid available at meniscus 54 for coating the sheet can be accurately controlled by varying the depth of throat 28, and in the example given, a depth in the range of .040 inch to .060 inch has
proved satisfactory in that it insures start up of application immediately at the leading edge of a sheet contacts the roll, maintenance of a meniscus 54 of the proper size and application of the liquid in a precisely predetermined quantity. Reduction
of the depth of the throat will reduce the quantity of liquid available for application to the sheet while an increase in the depth of the throat will result in an increased quantity of liquid up to a point at which the throat no longer has an effect on
the quantity of liquid carried into contact with the sheet by the roll. Throat 28 serves an additional function and this is to distribute the liquid on the roll surface more uniformly throughout the length of the roll and together with meniscus 54
insures against gaps in the layer of liquid applied to the sheet. The provision of a throat 27 extending to the lowest part of the roll is important because it renders the applicator less level sensitive, that is, it minimizes the effects of the axis of
the roll not being disposed in a horizontal plane.
In the operation of the apparatus of the invention to apply a processing liquid to a photosensitive sheet, cover 16 is pivoted to an open position as the leading edge of the sheet approaches the passage between cover 16 and side section 26 and
rotation of roll 14 is commenced so that the leading edge of the sheet will meet a wet portion of the roll surface as the sheet enters the applicator and first contacts the roll. Meniscus 54 forms immediately so at that a continuous layer of liquid of
the required depth is applied to the sheet throughout the entire length of the sheet commencing at its leading edge and rotation of the roll is continued until the trailing edge of the sheet has advanced from contact with the roll whereupon roll rotation
is discontinued and the cover is pivoted to its closed position.
It should be noted that the applicator is relatively simple in both its construction and operation, being composed of a minimum of components only two of which move and only one of which comes into contact with the liquid. The applicator may be
formed of a variety of materials that are compatible with the processing liquid and preferably wettable thereby, including metals such as stainless steel and many of the organic plastic materials, for example, polypropylene.
Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
* * * * *
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