Self-Processing Film Unit With Liquid Applicator

The present invention relates to the field of photography and, more specifically, to self-processing or self-developing film units.

For over thirty years now, commercially available self-developing film units have included a rupturable pod or container holding a supply of a relatively high viscosity (compared to water) liquid processing composition. The pod is attached to a leading end portion of a sheet-like film component which includes one or more photosensitive layers and an image receiving layer. Following exposure in a self-developing camera, the film unit is advanced, pod first, between a pair of camera mounted compressive pressure applying rollers. Initial compression of the pod generates hydrostatic pressure in the liquid which is effective to rupture a rear pod seal and discharge the liquid in a pool between a predetermined pair of layers at the leading end of the sheet-like film component. As the film unit is further advanced between the rollers, the compressive force thereon causes the liquid to be spread in a thin, substantially uniform, layer between the predetermined film layers to imbibe the photosensitive layer (or layers) and initiate a well-known development and diffusion transfer process that results in the production of a positive image in the image receiving layer.

Those skilled in the art of processing self-developing film units in this manner will appreciate that the quality of the positive image is critically dependent upon successfully spreading the viscous liquid, which has a jelly-like consistency, to provide a thin layer of processing composition having a substantially uniform thickness over the entire image forming area of the film component.

The seemingly simple task of spreading a thin, uniform layer of viscous liquid between two opposed layers of the film component is, in fact, quite difficult because of the numerous variables in the process. These variables include the specific viscosity and flow characteristics of the liquid, the resistance to flow characteristics of the opposed layers of the film component which depend upon the surface tension parameters of the layers and the spacing therebetween, the amount and lateral distribution of pressure applied by the rollers, and the rate of film advancement therebetween.

Contemporary self-developing photographic systems, such as the SX-70, One-Step and Sun Camera Systems manufactured and marketed by Polaroid Corporation, Cambridge, Mass. employ so-called integral or non-peel-apart film units and compact cameras having motorized roller drive systems. In these photographic systems the spread control function is divided between structures in the film unit, the cassette holding a stack of such film units, the pressure applying rollers, and a film deflector on the exit side of the rollers.

Components of the film unit which influence spreading characteristics include the structural configuration of the pod and its rear seal rupture characteristics, along with internal masks or side rails within the film component that the rollers ride along to control thickness of the liquid layer. The cassette is formed with a precision tapered wall section near the film exit slot which bears on an upper surface of the film unit as it is advanced into the rollers to control the shape of the pool of liquid discharged from the pod. The rollers are manufactured to extremely high tolerances and at least one of them may include an assymetrical shape, e.g. non-cylindrical tapered sections and red bar grooves of different configurations at opposite ends of the roller. The rollers are mounted in a precision spring biased bearing block assembly which controls the roller gap and the amount of compressive force applied by the rollers. The film deflector on the exit side of the rollers is precisely located with respect to the roller bite line or gap to induce a controlled large radius curve in the exiting portion of the film unit which further influences the liquid spreading in a beneficial manner.

While the above noted film, cassette, and camera structures and components provide excellent control over the liquid spreading function, they do add significant cost to the system because of the extremely tight tolerances to which these components must be manufactured and assembled.

Recognition of the undesirable high cost of precisely spreading a relatively high viscosity liquid processing composition has led to many proposed alternative systems that are well-known in the prior art.

Some of these alternative systems contemplate treating or wetting one outer surface of the exposed film component with a low viscosity (similar to water) liquid processing composition and employ a wide variety of structures and mechanisms to deliver the liquid to the surface that is to be wetted. The low viscosity liquid tends to be self-spreading and is much easier to disperse in a uniform manner than is the high viscosity liquid thereby dispensing with the need for elaborate and costly spread control components.

Other alternative self-developing film systems approach the problem by providing a pre-distributed layer of highly viscous or micro-encapsulated liquid processing composition on a separate processing sheet or web incorporated into the film component along with the photosensitive layers.

For representative examples of the latter approach, see commonly assigned U.S. Pat. No. 2,558,857 which discloses an elongated liquid and air impervious processing web coated with a jelly-like processing composition, and commonly assigned U.S. Pat. Nos. 2,543,181 and 3,306,747 wherein the processing liquid is pre-distributed within the film unit in a layer of micro-capsules or other frangible micro-containers, or is provided in a liquid impermeated layer of porous absorbent materials such as blotter paper.

Representative examples of self-developing film systems wherein the outer surface of an exposed photosensitive sheet is intended to be wetted with a low viscosity processing liquid may be found in U.S. Pat. No. 3,179,517 and commonly assigned U.S. Pat. Nos. 3,314,792; 3,345,165 and 3,907,563 wherein a processing web roll that is pre-soaked with a low viscosity liquid or is wetted just prior to processing is brought into face to face contact with an exposed photosensitive sheet to wet its outer surface and initiate the development process. Also, see commonly assigned U.S. Pat. Nos. 3,069,266 and 3,498,203 for examples of structures wherein a low viscosity processing liquid is delivered to the exposed film surface by means of various capillary action applicators.

U.S. Pat. No. 4,310,620 discloses a method of processing a photographic material by establishing contact between an outer surface of the material and a variety of flat, porous, capillary action spreading element impregnated with a low viscosity processing liquid. The spreading elements are porous structures in the form of individual sheets which may be woven or knitted fabrics, or non-woven webs of paper, or porous plastic or metal layers, or sponge or foam-like material, or hydrophillic material if an aqueous processing liquid is used. The spreading sheets may be presoaked with sufficient liquid to process a single film unit or may be provided in combination with a container of liquid that serves as a reservoir for providing additional liquid when the required volume of liquid for complete processing exceeds the liquid holding capacity of the spreading sheet. In one embodiment, the liquid impregnated sheet is initially provided in a water impervious container formed by laminating a water impervious foil on both sides of the impregnated spreader sheet. Before use the foil is stripped from one side to expose the impregnated spreading sheet which is then brought into contact with the surface of the exposed photographic material. In another embodiment, a rupturable container holding the processing solution is placed along one end of the spreading sheet. With this type of structure, the spreading sheet is placed on the photographic material surface and the two elements are advanced between pressure applying rollers which rupture the container and discharge the liquid so it is absorbed by the spreading sheet and transferred by capillary force to the outer surface of the photographic material. After processing, the spreading sheet may be stripped away or may be left in place.

As noted earlier, the cost of self-developing film units and cameras for exposing and processing these film units may be reduced substantially by switching from a high viscosity, jelly-like, liquid processing composition, to an easier spreading low viscosity processing liquid having a viscosity similar to water to eliminate the costs associated with providing precision film and camera components for accurately controlling the spread of high viscosity processing compositions.

The prior art self-developing film systems that employ a low viscosity processing liquid, noted above, have several drawbacks that severely limit their potential for commercial viability. For example, those systems that utilize a web roll of film component and a processing web roll that is to be wetted with the liquid and brought into face-to-face contact with the exposed film component require relatively large and awkwardly shaped camera housings to accommodate the web holding spools. Also, a cutting device is required for severing the individual frames after processing. Perhaps a more serious limitation is the need to provide complex liquid holding tanks or containers and seals for the exit slots thereof to prevent evaporation of the liquid and/or environmental contamination or degradation. Also, if the liquid is to be delivered intermittently to process successive film frames there is a tendency for porous or capillary applicators to clog as a result of dried fluid that crusts over the applicator tip.

While the porous capillary action spreading elements and liquid reservoir containers associated therewith described in the previously noted U.S. Pat. No. 4,310,620 apparently are designed for use with individual sheet components, as well as web roll film, the enumerated embodiments do not seem to be particularly practical for easy and reliable use and manipulation. For example, to use the embodiment wherein a pre-soaked pad or spreading element is enclosed in a water impervious container formed by foil sheets laminated on opposite sides of the spreading element, first one of the outer sheets must be stripped away to expose the surface of the spreading element which then must be registered over and placed in contact with the film surface to be wetted. Also, this means some provision must be made for conveniently disposing of the foil layer that is stripped away. In another embodiment, wherein the liquid is held in a rupturable pod at one end of the spreader element the applicator assembly must be moved into registration with the film element before the two are advanced between the pressure rollers. If the spreading element is predisposed over the surface to be wet during manufacture, that film surface is eliminated as an exposure surface thereby imposing a limitation on variety of film structures that may use this type of applicator.

Therefore, it is a primary object of the present invention to provide a low-cost, self-developing film unit that utilizes a low viscosity liquid processing composition and is easy and convenient to use. It is yet another object of the invention to provide such a film unit comprising a sheet like film component including an outer surface having a given predetermined area thereof that is to be wetted with such a low viscosity processing liquid to initiate processing, and a liquid applicator attached to the film component holding a supply of liquid sufficient to wet the given area.

It is yet another object of the invention to provide such a film unit wherein the applicator is preregistered with respect to the given area of the film component during manufacture.

Another object of the invention is to provide such a film unit wherein a component of the applicator initially serves to form a liquid and air impervious enclosure about the supply of processing liquid and is configured to be easily manipulated, following exposure, to present the liquid in face-to-face contact with a given area to effect wetting thereof.

Yet another object of the invention is to provide such a film unit that is configured to be compatible with a processing mechanisms for liberating the liquid from its applicator enclosure and delivering it to said given area.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

The present invention provides a low-cost, self-developing (or self-processing) film unit comprising a sheet-like film component and a liquid applicator secured thereto. The sheet-like film component includes one or more photosensitive layers and has an outer surface with a given area thereof that is configured to be wetted with a low viscosity processing liquid to initiate processing of the one or more photosensitive layers.

The liquid applicator is secured to the film component, outside of the given area, and includes a liquid and air impervious sheet dimensioned for extension over the outer film component surface in covering relation to the given area, and means on one surface of the impervious sheet yieldably holding a substantially uniformly distributed supply of low viscosity processing liquid sufficient to wet the given area. The applicator is initially provided on the film component in a folded and releasably sealed configuration wherein the impervious sheet forms a liquid and air impervious enclosure about the liquid holding means. Following exposure, the applicator is configured for movement to an unsealed extended configuration overlying the outer surface with the liquid holding means in liquid yielding contact with the given area to effect wetting thereof.

In one embodiment, the impervious sheet carries on one surface thereof a porous liquid holding structure, such as an absorbent pad or the like, presoaked with the low viscosity liquid processing composition. Initially, during manufacture, the impervious sheet is folded over on itself so that the liquid holding pad is disposed on an interior surface of the impervious sheet. Then the three open sides of the impervious sheet are releasably sealed to form a hermetically sealed enclosure surrounding the liquid holding pad. The sealed applicator, in its folded initial configuration, is secured to an end portion of the sheet-like film component so as to be accurately aligned and registered with respect to the given area.

Following exposure of the film component, a portion of the enclosure formed by the folded impervious sheet is engaged by a processing mechanism and is moved toward the opposite end of the film component so as to peel back the marginal seals and deploy the impervious sheet in an extended configuration over the outer surface to locate the liquid holding pad in facing relation to the given area. In the illustrated embodiment, the deployed impervious sheet and the film component are advanced between a pair of pressure applying rollers which urge the wetted pad into good contact with the given area to effect wetting thereof. Because the rollers only serve to establish contact between the liquid soaked pad and the outer surface of the film component, they may be manufactured to much less rigid standards than rollers that are employed to control the spread of high viscosity liquids, thereby significantly reducing the overall cost of the film processing mechanism.

For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description with accompanying drawings wherein:

FIG. 1 is a perspective view of a self-processing film unit embodying the present invention showing a liquid holding applicator in its initial folded and sealed position secured to one end of a sheet-like film component;

FIG. 2 shows the film unit of FIG. 1 with the applicator in an unsealed partially opened position;

FIG. 3 shows the film unit of FIG. 1 with the applicator deployed in a tent-like configuration over a forward position of the film component;

FIG. 4 shows the film unit of FIG. 1 with the applicator in its fully extended processing position overlying the film component;

FIG. 5 is a longitudinal cross-sectional view of the film unit of FIG. 1 taken along 5--5;

FIG. 6 is an enlarged diagrammatic cross-sectional representation showing the layers of color diffusion transfer type film component;

FIG. 7 is an enlarged diagrammatic cross-sectional representation of an impervious sheet employed in the applicator;

FIG. 8 is a perspective view of the applicator shown in its initial folded position;

FIG. 9 is a perspective view of an alternative embodiment of the film unit incorporating the present invention;

FIGS. 10-14 are sequential side elevational views, partially cut away in some instances, of a processing apparatus for use with the film unit embodying the present invention showing the operational steps of the apparatus;

FIG. 15 is a forward looking elevational view of an applicator erecting arm assembly forming part of the processing apparatus; and

FIG. 16 is a rearward looking elevational view of the erecting arm assembly .

The present invention provides a low-cost, self-developing film unit 10, shown in FIGS. 1, 2, 3 and 4, comprising a sheet-like photosensitive film component 12 and processing liquid applicator 14 secured to one end position of component 12 and holding therein a supply of low viscosity liquid processing composition.

Broadly speaking, the film component 12 includes a base or support sheet having one or more layers coated thereon including one or more photosensitive layers that are adapted to be exposed to actinic radiation to form a latent image therein. Following exposure, the liquid processing composition in applicator 14 is brought into contact with a designated outer surface of film component 12, such as the top surface 16 shown in FIG. 1, to wet a predetermined given area thereof, such as the rectangular area 16a bounded by dotted lines 18, that generally coincide with a delineated image forming area to initiate processing of film component 12 which may include the step of developing the latent image in the exposed photosensitive layer or layers.

In the illustrated embodiment, applicator 14 includes a liquid and air-impervious sheet 20 (see FIG. 5) secured to a leading end portion of film component 12 outside of the bounds of the given area 16a. Sheet 20 is dimensioned for extension over the outer film component surface 16 in, at least, covering relation to area 16a. The applicator 14 also includes, on one surface of sheet 20, means for yieldably holding a substantially uniformly distributed supply of a low viscosity processing liquid sufficient to wet the given area 16a, for example, a rectangular or square absorbent or porous pad 24, or the like, soaked with a processing liquid 26 and disposed on a central area of an interior surface 27 of sheet 20.

The applicator 14 is initially provided on component 12, during manufacture, in the folded substantially flat configuration shown in FIGS. 1 and 5 wherein sheet 20 is folded back over on itself and is releasably sealed along two longitudinally extending marginal portions 28 and 30 and a transverse and laterally extending marginal portion 32 to form a liquid and air-impervious enclosure about the liquid holding means or pad 24 which also assumes a folded configuration on the interior surface 27 of sheet 20. When so folded, sheet 20 defines opposed enclosure wall sections 31 and 33.

After exposure of the photosensitive layer or layers of film component 12 which may be accomplished by directing image forming light or radiation onto top surface 16, or alternately, depending on the type of film construction, onto the bottom outer surface 34 opposite surface 16, the applicator 14 is moved from the folded sealed position to the unsealed extended processing position by urging or peeling wall sections 31 and 33 apart to unseal the marginal portions 28, 30 and 32 and extending sheet 20 rearwardly, as shown in the sequence of FIGS. 2, 3 and 4, so that it overlies outer surface 16 with the liquid holding means or pad 24 in liquid yielding contact with the given area 16a to effect wetting thereof. Depending on the type of film construction (a variety of which will be discussed later) the extended applicator 14 may be stripped away from surface 16 following a suitable imbibition period, or it may be left in place to form a permanently attached component, such as a protective cover sheet, of the processed film unit 10.

Film unit 10 offers many advantages over prior art self-developing film units that employ a jelly-like high viscosity liquid and other prior art self-processing film systems, described earlier, that utilize a low viscosity processing liquid.

Because the low viscosity processing liquid is substantially uniformly distributed by the soaked pad 24, the need to provide precision film and camera components and mechanisms to uniformly distribute the liquid with respect to the surface to be wetted is eliminated, thereby providing substantial cost savings. Also, by using a low viscosity liquid that has flow characteristics similar to water, transfer of the processing composition from the liquid holding means on the extended applicator 14 to the surface area 16a is readily accomplished by capillary action. The only requirement for such transfer to take place is to establish good contact between the facing surface of pad 24 and the surface area 16a which may be accomplished by advancing the film unit 10, with applicator 14 extended, between a pair of pressure applying rollers to press these two elements together as will be described later in detail. Advantageously, the rollers may be of relatively inexpensive construction because, in light of the predistribution of the liquid, they do not have to perform a liquid spreading function which would require expensive rollers manufactured to high tolerances to achieve the desired uniformity.

Another advantage of film unit 10 is that it does not require any trap structure at the trailing end to receive and store excess liquid as do film units that employ a high viscosity liquid which is discharged from a pod and progressively distributed between a pair of film layers from the leading to trailing end of the film unit.

Perhaps a more important advantage lies in the fact that film unit 10 combines in one simply constructed structure all of the necessary elements for processing the exposed film component 12 with a low viscosity liquid. That is, film unit 10 includes a self-contained supply of a low viscosity processing liquid which is protected from evaporation and environmental contamination by the liquid and air impervious enclosure formed by the folded and sealed sheet 20. Advantageously, the sheet 20 performs multiple functions. Because it is secured during manufacture to film component 12, in a predetermined position with respect to surface area 16a, sheet 20 serves as means for precisely aligning and registering the liquid holding means or pad 24 with respect to the surface area 16a thereby eliminating the need for processing mechanism structure to perform the registration function. When sheet 20 is extended, it serves to support and guide the attached soaked pad 24 to its operative processing position overlaying film component 12. Also, in addition to its earlier noted function of providing a liquid and air impervious enclosure for pad 24 when it is folded and releasably sealed, sheet 20 may serve as a protective cover sheet on one side of film component 12 if the extended applicator is to be left in place after completion of processing.

Another advantage of film unit 10 is that the applicator 14 is mounted on film component 12 outside of the boundaries of the predetermined image forming area 16a so as not to interfere with or block the film exposure process. By mounting applicator 14 on one end of film component 12, either of the outer surfaces 16 or 34 are available as exposure surfaces. The choice of whether to expose through the top or the bottom of the film component of course would depend on the design of the particular type of film utilized.

The types of film components 12 that may be combined with the applicator 14 to form a film unit 10 envisioned by this invention include, but are not restricted to, conventional black and white negative materials; and self-developing or instant diffusion transfer film including integral or peel apart type black and white and color reflection print and transparency films which include, in addition to the photosensitive layer or layers, an image receiving layer on which silver complexes or image dyes are deposited by diffusion, as a function of developing the exposed photosensitive layers.

The term "processing" in the context of this disclosure simply means wetting the surface area 16a with a low viscosity processing liquid to ultimately produce a desired photographic processing result. The particular processing that actually takes place is determined by the chemical properties of the liquid and the layer or layers of film component 12. The process resulting from wetting surface area 16a may be complex, for example, a development and diffusion transfer process associated with color self-developing films, or the process may be quite simple and limited to a single step such as developing. The processing liquid 26 may simply be water which is used to activate processing chemicals that are predisposed in selected layers of film component 12. Again, the present invention is intended to provide a film unit which includes a photosensitive film component and a self-contained supply of low viscosity processing liquid which is attached to the film component 12 in the form of an applicator 14 which is initially provided in a folded configuration to protectively enclose the liquid and is movable to an extended processing position to bring the liquid into wetting contact with a predetermined area of the film component 12 to initiate "processing," as broadly defined above, of the film component 12.

For a representative example of one type of photosensitive film component or laminate 12 that may be used in combination with the disclosed liquid applicator 14 to form a film unit 10 embodying the present invention, reference is made to FIG. 6 showing, in diagrammatic form, a color diffusion transfer process film unit component 12.

The illustrated photosensitive film component or laminate 12 is adapted to be exposed in a camera to image forming actinic radiation incident upon one side of component 12 as indicated by the arrow in FIG. 6 designated "expose." Subsequent to development and diffusion transfer of image dyes, a positive image is formed, in a dyeable image receiving layer viewable through the opposite side of component 12 as indicated by the arrow designated "view."

Starting on the exposure side, the layers comprising component 12 include, in sequence, a blue sensitive silver halide emulsion layer 40; a yellow dye developer layer 41; interlayer 42; a green sensitive silver halide emulsion layer 44; a magenta dye developer layer 43; interlayer 46; a red sensitive silver halide emulsion layer 48; a cyan dye developer layer 49; an opaque layer 50; a light-reflecting layer 51; a transparent, dyeable image-receiving layer 52; a transparent spacer or timing layer 54; a transparent neutralizing or acid layer 56; and a transparent support 58 on which the above-noted layers are coated in the reverse sequence of their identification herein, and through which the positive image is viewed.

Following exposure of the three photosensitive emulsion layers 40, 44 and 48 by directing image-forming actinic radiation onto the outer surface area 16a of layer 40, the liquid applicator 14 is moved from its folded position to its extended position to bring the pad 24 soaked with the low viscosity liquid processing composition 26 into engagement with surface area 16a to effect wetting thereof with liquid 26.

The low viscosity processing liquid 26 includes as a primary ingredient thereof an aqueous solution of an alkaline material, for example, potassium hydroxide, or the like, in a concentration to provide the appropriate pH for the process.

The permeation of liquid 26 initiates development of the exposed photosensitive emulsions. The associated dye developers are immobilized or precipitated in developed areas as a consequence of such development. In unexposed and partially exposed areas of the photosensitive emulsions, the unreacted dye developers provide imagewise distributions of diffusible dye developer. At least part of these imagewise distributions of diffusible dye developer is transferred, by diffusion, through the opaque layer 50 and the light-reflecting layer 51 to the image receiving layer 52, to provide a positive color image of the developed image. After a predetermined time, liquid 26 permeates through the spacer or timing layer 54, and it reacts with the neutralizing acid layer 56 which is effective to cause reduction in the pH of the liquid to a predetermined pH. This reduction in pH level serves to stabilize the image.

The light-reflecting layer 51 is preferably white, e.g., titanium dioxide, to provide a suitable background against which the transferred dyes in the transparent image receiving layer 52 are viewed. The light-reflecting layer 51 in combination with opaque layer 50, e.g., of carbon black, prevent exposure or fogging of the photosensitive emulsions by light incident upon the viewing side of film component 12. If the extended applicator 14 also includes at least one opague layer, it serves to block unwanted exposure from the opposite side once it is in place thereby allowing completion of the film processing cycle to take place in an actinic environment, such as outside of the camera. That is, if the applicator 14 is opaque and is extended over outer surface 16 before the film unit exits the camera, the extended applicator 14 in combination with the light blocking properties of light-reflecting layer 50 and opaque layer 51 prevent further exposure of the emulsions 40, 44 and 48 thus allowing the film unit 10 to be removed from the camera before the processing cycle has been completed.

While the illustrated diffusion transfer film component 12 of film unit 10 shown in FIG. 6 is configured for exposure through one side and viewing through the opposite side, it should be understood that the present invention is not restricted to the use of such a film component 12. That is, other types of diffusion transfer film components 12 having different arrangements of layers may be combined with applicator 14 to provide a film unit 10 embodying the present invention. For example, the film component 12 may be configured so that it is both exposed and viewed through one side and processed by wetting that same one side or the opposite side. Alternatively, the film component may be configured to be peeled apart after processing at a designate layer interface to reveal the diffusion transfer image. Film components 12 may be provided wherein opaque layer 51 is omitted. In this case the processing must take place in a light excluding environment to prevent fogging. Also, the film component 12 may be configured so that the processing liquid is applied to an outer surface through which the diffusion image is viewed subsequent to processing, if the used sheet 20 is removed to uncover the image.

As noted earlier, it is within the scope of the present invention to utilize any suitable type of photosensitive film component 12 in combination with applicator 14 to form a self-processing film unit 10. Diffusion transfer film components 12 may be integral or peel-apart types; black and white or color; reflection print or transparencies. Also, the film component 12 may be a conventional negative sheet.

The construction of photosensitive materials like film component 12 is well known and described in the literature. Since the particular photographic process embodied in such film components forms no part of the present invention, such processes and film components need not be described in detail herein. Nevertheless, U.S. Pat. Nos. 3,594,164 and 3,888,669 and British Pat. No. 1,330,524 may be noted as illustrative descriptions of photosensitive materials of the general type illustrated in FIG. 6 and employing a variety of image dye-forming materials, dye developers being preferred in the noted U.S. patents.

As noted above, this invention may be utilized with a variety of photographic imaging systems to give black and white or color images. Thus, a black and white negative image may be obtained, without the formation of a positive transfer image, by using a photosensitive element and a processing composition such as that described in U.S. Pat. No. 3,721,562. Black and white silver transfer images may be obtained, for example, by the use of a layer arrangement such as shown in U.S. Pat. No. 3,705,804.

The image dye-providing materials which may be employed in such processes generally may be characterized as either (1) initially soluble or diffusible in the processing composition but which are selectively rendered non-diffusible in an imagewise pattern as a function of development; or (2) initially insoluble or non-diffusible in the processing composition but which are selectively rendered diffusible or provide a diffusible product in an imagewise pattern as a function of development. These materials may be complete dyes or dye intermediates, e.g., color couplers. The requisite differential in mobility or solubility may, for example, be obtained by a chemical action such as a redox reaction or a coupling reaction.

As examples of initially soluble or diffusible materials and their application in color diffusion transfer, mention may be made of those disclosed, for example, in U.S. Pat. Nos. 2,968,554; 2,983,606; 3,087,817; 3,345,163; and 3,443,943. As examples of initially non-diffusible materials and their use in color transfer systems, mention may be made of the materials and systems disclosed in U.S. Pat. Nos. 3,185,567; 3,230,082; 3,443,939; 3,443,940; 3,227,550; 3,227,552; 3,719,489; and 4,076,529.

It is also to be understood that the silver halide emulsions may be negative-working or positive-working (e.g., internal latent image emulsions), depending upon the particular image dye-providing substances employed and whether a positive or negative color transfer image is desired.

As noted earlier, sheet 20 of applicator 14 in its folded and releasably sealed configuration of FIGS. 1 and 5 forms a liquid and air impervious enclosure about pad 24 to prevent evaporation of the liquid 26 therein and to protect the liquid from contamination by elements in the environmental atmosphere from the time sheet 20 is sealed at manufacture until it is unsealed at the time of use.

Typical material suitable for use as applicator sheet 20 preferably are alkali resistant composite materials such as the type shown in FIG. 7 comprising a multi-layer laminate formed by a outer sheet or layer 60; a middle sheet or layer 62, and an inner sheet or layer 64 having the surface 27 on which the liquid holding means or pad 24 is carried.

The outer sheet or layer 60 is a thin, flexible, relatively inexpensive, tough material which may be a plastic but which is preferably an opaque paper such as kraft paper. The middle layer or sheet 62 is a thin, impervious sheet material such as metal foil, for example, a lead or very soft temper aluminum foil, approximately 0.001 inch in thickness and attached to outer sheet 60 by any simple means known to the art such as adhesive bonding or the like. The inner layer 64 is preferably a thermoplastic resin, inert to the liquid processing composition 26 and its vapors, such as polyvinyl chloride which may be adhered to the metal foil layer 62 by coating and/or laminating procedures well known in the art.

For a more detailed description of laminate materials suitable for use as sheet 20 along with examples of alternative materials that may be used in the individual layers thereof, reference may be had to commonly assigned U.S. Pat. Nos. 3,056,491; 3,056,492; 3,833,381; and 4,303,750 all of which are incorporated by reference herein.

The liquid holding pad 24 disposed on surface 27 of layer 64 of sheet 20 an absorbent and/or porous material which resists deterioration when in prolonged contact with the liquid 26. Such absorbent and/or porous materials include woven and non-woven sheet materials, natural and synthetic sponge materials, fibrous or cellulosic containing materials such as absorbent papers (e.g. blotters), natural or synthetic fiber textiles, porous plastic sheets and foils, plastic or other synthetic foams, and the like.

The liquid holding means on pad 24 may be formed as a separate sheet which is adhered, in its dry state before introduction of liquid 26 therein, to the thermoplastic layer 64 by adhesive or thermocompression bonding or the like. Alternatively, pad 24 may be provided initially in a form that allows it to be adherently coated, sprayed, or otherwise deposited on layer 64 so that the liquid holding means is formed in situ on sheet 20.

One representative example of a material that has been successfully employed as a liquid holding pad 24 is a non-woven sheet of polypropylene fiber, 0.004 inch thick, anufactured by the Kendall Corporation under the trade designation Webril non-woven sheet.

The liquid applicator 14 is formed separately from the film component 12 during manufacture. As best shown in FIG. 8, the sheet 20 with pad 24 on interior layer 64 is folded back over on itself so that its upper trailing end edge 70 of wall section 31 is forward of its lower trailing end edge 72 of wall section 33 to provide an outwardly projecting and laterally extending tab 74 which is used as a point of attachment to permanently secure applicator 14 to the leading end 22 of film component 12 as will be described later.

Just forwardly of the upper trailing end edge 70, the underlying portion of wall 33 has two notches 76 cut therein at the lateral margins. These notches 76 provide access for a later to be described mechanism for engaging the overlying registered portions 78 on wall 31 and applying a force to the applicator to urge walls 31 and 33 apart and thereby peel open the marginal seals 28, 30 and 32.

The lateral marginal seals 28 and 30 and the longer transverse rear seal 32 may be formed by applying heat and/or pressure to the corrresponding superposed portions of the folded sheet 20 to effect adherence of the facing surfaces of the thermoplastic inner layer 64 outboard of the central area thereof on which pad 24 is disposed.

The liquid 26 may be applied to pad 24 before any of the seals are made with sheet 20 and pad 24 thereon either in a planar extended position or in the folded over configuration. Alternatively, sheet 20 may be folded and partially sealed before application of the liquid 26 to pad 24. In this instance, any one or two of the seals are made before the liquid is injected onto pad 24 through one or more of the remaining open sides which are then sealed following introduction of the liquid 26. The preferred sequence for wetting pad 24 and making the releasable seals 28, 30 and 32 will, of course, depend on the choice of design of high volume production machinery for manufacturing the applicator 14 in an efficient and cost-effective manner.

In the illustrated embodiment, cover sheet 20 is light opaque and the extended applicator 14 is intended to serve as a light blocking cover sheet for the exposure side of film component 12 so that the film unit 10 may be advanced directly into an actinic radiation environment following deployment of the applicator 14 to its extended processing position. Because the film component 12 provides a viewable image on the opposite side from the surface to be wetted, the extended applicator 14 may be adhered to film component 12 and left in place permanently following completion of processing. In this instance, the extended applicator 14 also serves a a long-term protective cover sheet or barrier layer that protects the exposure side of film component 12 from atmospheric contamination or degradation, for example, by inhibiting oxidation.

Even if applicator 14 is used with a film component 12 requiring the extended applicator 14 to be stripped away from outer surface 16 after the completion of processing, either simply to remove pad 24 from engagement with surface area 16a or to unblock a viewing surface in those film components that are structured so that the desired image is viewed through the surface to be wetted, it may be preferable to at least temporarily secure the periphery of the extended sheet 20 outboard of the pad 24 to the corresponding facing portions of the surface 16 to inhibit light and/or liquid leakage at this interface during processing.

In such an application the peripheral area of layer 64 of sheet 20, along the three sides thereof that are not attached to the leading end of component 12 at 22, may be coated with a reusable adhesive material that releasably bonds to itself when sheet 20 is folded to form the strippably releasable marginal seals 28, 30, and 32 and retains its adhesive properties so that it can be used again as adhesive to adhere these peripheral portions of layer 64 to the facing portions of surface 16 when applicator 14 is extended and pressed into contact therewith.

Alternatively, the peripheral portions of layer 64, along the three free sides thereof, may be initially coated with a dry contact type of adhesive which does not adhere to itself but will adhere to a complementary dry contact adhesive that is precoated on the facing peripheral portions of surface 16. In this instance, after sheet 20 is folded, the marginal seals 28, 30 and 32 may be formed, by the application of heat and/or pressure, as thin linear seal lines disposed on the outboard edges of pad 24 but inboard of the dry adhesive coating so that the seals are made between facing linear portions of the thermoplastic resin layer 64. Thus, in such an embodiment, the initial seals are made by thermocompression bonding and, after sheet 20 is extended and pressed into place, the peripheral or secondary seals are made by adhesive bonding.

In another alternative embodiment, the outer periphery along the three free sides of layer 64 may be provided without any additional adhesive coating thereon and may be heat and/or pressure sealed as noted above; and the corresponding facing peripheral area of the film component outer surface 16 may be precoated with a dry adhesive that is activated when contacted by the processing fluid 26 from pad 24. In this case, pad 24 would be made a little wider and longer to come in contact with at least the edge portions of the dry adhesive thereby activating the adhesive to form the bond when the applicator 14 is extended and brought into contact with surface 16.

As best shown in FIG. 5, the liquid applicator 14 is attached to the leading end 22 of film component 12 by folding the projecting trailing end tab 74 back under the bottom of the folded applicator 14 and securing its thermoplastic resin layer 64 to the facing, transversely extending, leading end portion of the film component outer surface 16 by any suitable means such as an adhesive bond suggested at 80. In FIG. 5 the marginal seals also are made by adhesive bonding employing a reusable adhesive suggested at 82 and 84.

As noted earlier, attaching applicator 14 to film component 12 at manufacture provides in a single film unit 10 all of the materials necessary for processing the film unit following its exposure. Also, by mounting applicator 14 on component 12 during the manufacturing process it is accurately aligned in position thereon so that the liquid holding means or presoaked pad 24 will be correctly registered with respect to the given surface area 16a on outer surface 16a when applicator 14 is moved to its extended position.

The applicator 14 may be secured to film component 12 in ways other than as shown in FIG. 5. For example, the tab 74 may be left in its outwardly projecting state, shown in FIG. 7, and be bonded to the underside of film component 12 on the outer surface of the bottom transparent layer 58.

The bond between the applicator 14 and component 12 must be strong enough to resist detachment of applicator 14 during its movement from its preregistered position due to the strain imposed on the bond when the applicator is unsealed and moved to its extended position. If the extended applicator 14 is to permanently remain on surface 16 after processing is complete, the bond at 22 may be permanent. However, if applicator 14 is to be removed after the completion of processing, the bond is preferably of the releasable type that can be stripped apart manually upon application of a peel-apart force that is greater than the forces applied to sheet 20 during extension of applicator 14. Alternatively, if the bond at 22 is not releasable, sheet 20 may be perforated adjacent the bond and simply be torn off after processing leaving a small bonded portion thereof on the leading end 22 of film component 12.

The applicator 14 may be initially provided on the film component 12 in the configuration shown in FIG. 1 or 5, wherein it extends forwardly out beyond the leading end 22, or it may be folded back over component 12 to provide a more compact configuration for packing and storage, wherein it overlies the forward half of outer surface 16 is substantially parallel relation thereto as shown in FIG. 9.

If surface 16 is the exposure surface, the applicator 14 will have to be pivoted upwardly away from surface 16 at least to a position sufficiently upright with respect thereto so the applicator 14 does not intrude into the cone of image forming light directed at the image area 16a.

FIGS. 10 through 16 show one type of processing apparatus 90 especially configured to manipulate an effect processing of a film unit 10 configured as shown in FIG. 9. Broadly speaking, the illustrated apparatus 90 includes; means for supporting the film unit 10; means for moving the applicator 14 from its overlying position of FIG. 9 to an upright position, shown in FIG. 12, in preparation for exposure and the subsequent unsealing of the marginal seals 28, 30 and 32; and means for moving the unsealed applicator to its extended position for locating the liquid soaked pad 24 in liquid yielding contact with the surface area 16a of film component 12.

Major components of processing apparatus 90 include a base 91 having a platen-like member 92 which includes: an upper horizontal film surface 94; a pivoting applicator erecting arm assembly 96 for engaging the applicator 14 and pivoting it upwardly from its flat initial position to its substantially upright erected position (as shown in the sequence of FIGS. 10 through 12) in preparation for film exposure in subsequent operations for unsealing the marginal seals 28, 30 and 32; a pick assembly 98 mounted for reciprocating motion for first unsealing the marginal seals and then advancing the film unit 10; and a pair of juxtaposed pressure applying rollers 100 and 102 between which the film unit is advanced to press the liquid soaked pad 24 into good contact with surface area 16a as shown in the sequence of FIGS. 13 and 14.

Means for supporting the film unit 10 include support surface 94 and laterally extending upstanding leading and trailing end stops or ribs while 104 and 106 thereon would selectively limit longitudinal movement of the film unit 10, as will become apparent later. The support means also includes a pair of upstanding side rails for limiting lateral movement of the film unit. In an alternative preferred embodiment, apparatus 90 may be built into a self-developing camera, and a plurality of stack units 10 may be provided in a cassette which is supported in a receiving chamber in platen 92. In this case, the forward-most film unit 10 would be supported within the cassette at the same position to find for the illustrated single film unit 10 by surface 94, and the stops or ribs 104 and 106 would be integrally formed on the opposing leading and trailing end walls of the cassette.

FIG. 12 diagrammatically shows the objective lens 108 of such a camera and the outer boundry lines 110 of a cone of image forming light projected by lens 108 onto the outer surface 16 of the film component 12 supported at a defined exposure position on support surface 94.

The initial function of apparatus 90 is to pivot the applicator 14 upwardly from its folded down position of FIG. 10 to its substantially upright exposure position of FIG. 12 outside of the cone of image forming light bounded by lines 110 so as not to block or intrude into the light path between lens 108 and the film component 12 supported on surface 94.

FIG. 14 shows the applicator erecting arm 96 from its rear side facing the film support surface 94 and FIG. 16 shows it fom the opposite forward facing side. Assembly 96 is mounted between a pair of laterally spaced upright supports 111a and 111b on base 91. It includes a pivoting thin, flat, sheet metal erecting arm 112 that extends laterally between supports 111a and 111b and includes a pair of depending legs 113 and 114 at opposite ends thereof. Leg 113 is fixed to the inside face of a gear 115, by a screw 115a, that is fixed to a rotatably mounted short shaft 116 on support 111a. Leg 114 pivots on an inwardly extending fixed short shaft 117 mounted on support 111b.

As best shown in FIGS. 15 and 16, the plate-like major portion of arm 112 has a thin sheet metal plate 118 pivotly mounted on the side thereof for movement between the retracted position shown in solid lines in FIG. 15 and the extended position shown in dotted lines. Plate 118 includes an intregally formed outwardly extending hook member 120 that is adapted to engage the fold line or leading end 122 of the applicator 14. Plate 118 is pivotly coupled at its right end (as viewed in FIG. 15) to arm 112 at pin 124. A curved guide slot 126 is provided at the opposite end of plate 118 for receiving an outwardly projecting pin 128 on arm 112 that has a peened over head 130 for retaining the left end of plate 118 in close sliding contact with the facing surface of arm 112. Below slot 126 is a depending foot 132 that passes through an offset opening 134 in arm 112 and has a lower cam follower end 136 in engagement with the peripheral cam surface of an eccentric cam 138 that is rotatably mounted on shaft 117 and fixedly secured to the inside face of a gear 139 adjacent thereto that is also free to rotate about shaft 117. The drive structure for rotating gear 115 to pivot arm 112 between its operative positions and to rotate gear 139 for effecting rotation of cam 138 will be discussed later.

Plate 118 is biased downwardly toward its retracted position by a torsion spring 140 mounted on the backside of arm 112. Spring 140 has its center coiled about a tab 142 on arm 112, the end of one arm 144 fixed to another tab 146 on arm 112 and the end of the other arm 148 secured to pin 150 on plate 118 that projects outwardly through a curved slot 152 in arm 112. In this manner, spring 140 provides a biasing force on plate 118 to maintain the cam follower 136 in engagement with cam 138.

The pick assembly 98 comprises a pair of elongated slide members 154 that ride in a pair of corresponding longitudinally extending channels 156 provided in platen 92, on opposite sides thereof, outboard of the lateral margins of a film unit 10 supported on surface 94. Integrally formed at the leading end of each slide member 154 is an upstanding and inwardly extending pick 158 which includes a rearwardly extending finger 160 for effecting unsealing of the marginal seals by extending through a corresponding notch 76 in applicator sheet 20 in response to rearward movement of the slide member 154 and pushing against the aligned portion 78 to separate the folded wall sections 31 and 33 of sheet 20, and a forwardly projecting finger 162 which, in response to forward movement of slide member 154, slides between the partially deployed applicator and component 12 and pushes on the applicator to film component connection to advance the film unit 10 into the bite of the pressure applying rollers 102 and 104.

Each of the slide members 154 has an elongated gear tooth rack 164 depending from the underside thereof which is in engagement with a corresponding one of a pair of pinion gears 166 that are fixed on opposite ends of a transversely extending shaft 168 rotatably mounted on base 91. In this manner, the slide members 154 are mounted on base 91 for linear reciprocating motion with respect to the film unit located at its operative position on support 94.

The pivotal motion of erecting arm 112 is limited to a predetermined arc segment by a curved guide member 170 that has a circular segment slot 172 which receives an upper guide pin 174 on arm 112. The lower end of guide member 170 is slideably pinned through an elongated slot 176 in slide member 154 by means of a peened over rivet 178. A fix stop 180 is provided on base 191 outboard of the slide member 154 and limits forward motion of the lower end of guide member 170 in slot 176 by the abutment of rivet 178 against stop 180.

In the illustrated embodiment, the means for driving the applicator erecting arm 112 and cam 138 includes a gear train and slip clutch arrangement. This mechanism includes a pair of laterally spaced idler gears 182 and 184 freely rotatable on a common shaft 186 having its opposite ends supported in bearings on the corresponding supports 111a and 111b, as best shown in FIG. 15. Gear 182 is directly below and in mesh with the erecting arm gear 115. Gear 184 is directly below and in mesh with the cam drive gear 139.

As best shown in FIG. 16, a rotatable shaft 188 having an integrally formed crank handle 190 on its left-hand end extends through a bearing block 192 on base 91 and into an aligned bearing on support 111b. A gear 194 is fixedly secured to shaft 188 and is in mesh with the corresponding idler gear 184 so that cam 138 is turned in response to rotation of shaft 188 through a cam drive train comprising gears 194, 184 and 139.

A gear and slip clutch arrangement 196 is provided on shaft 188 between crank handle 190 and bearing block 192. This arrangement comprises a hollow cylindrical body or tube 198 carried on shaft 188 and secured thereto, a clutch plate 200 integrally formed on body 198, a gear 202 rotatably carried on body 198 and in mesh with idler gear 182, a helical clutch spring 204 for urging gear 202 against clutch plate 200, and an adjustment nut 206 threaded on the outboard end of body 198 for adjusting the compression force of spring 204 acting to urge gear 202 against plate 200. The spring force is adjusted so that clutch plate 200 and the end of spring 204 frictionally drive gear 202 as body 198 rotates with shaft 188 without slippage provided that the load on gear 202 is below a predetermined maximum value. When this load value is exceeded, the clutch plate 200 and the end of spring 204 slip with respect to the side faces of gear 202 so that it no longer rotates when shaft 188 turns. This configuration allows limited independent operation of the applicator erecting arm 112 and the hook carrying plate 118 thereon with respect to the cam drive as will become apparent later. The pick mechanism 98 is driven back and forth along its linear reciprocal path by selectively rotating shaft 168 to drive the pinion gears 166 thereon. The rollers 102 and 104 are rotatably mounted on base 91, for example on a pair of stanchions 208 (only one of which is shown). At least one of the pair of rollers is power driven to advance the film unit 10 therebetween.

The pick mechanism 98 may be manually driven by providing a crank handle on shaft 168. A similar manual drive system may be provided for the pressure applying rollers. However, it is preferred to selectively drive the applicator erecting arm, pick mechanism and rollers with a motorized drive system comprising one or more small reversible electric motors, appropriate drive train components and a sequence control subsystem which may be provided by applying motorized drive system principles known in the art.

In operation, apparatus 90 functions as follows. The components of apparatus 90 are initially set as shown in FIG. 10 with the erecting arm 112 raised in its upright position, and cam 138 oriented so that the hook plate 118 is retracted. The pick slide members 154 are in a forward position to locate the picks 158 forwardly of the raised arm 112. The film unit 10 is located at its operative exposure position on plate 94 with the applicator 14 folded down over the forward half of outer surface 16 (exposure surface) of film component 12. When apparatus 90 is built into a camera, the raised erecting arm 112 may be accommodated within the confines of a bellows structure extending between the objective lens and the film support surface.

In response to rotating shaft 188 in a counterclockwise manner gears 194 and 202 thereon simultaneously drive gears 182 and 184 on shaft 186 in the clockwise direction. This motion of gear 182 drives gear 115 in a counterclockwise direction about shaft 116 thereby pivoting the erecting arm 112 downwardly to a position overlying the folded applicator 14, as best shown in FIG. 11. Gear 184 on the opposite end of shaft 186 drives the cam gear 139 in a counterclockwise direction at the same time. However, because the arm 112 is also pivoting downwardly at the same rate, through its connection with gear 115, there is no relative motion between the cam follower end 136 and the cam 138. Therefore, the hook plate member 118 remains in its retracted position until arm 112 engages the folded applicator 14. The abutment of erecting arm 112 against applicataor 14 prevents further downward rotation of erecting arm 112 and loads the gear train so that clutch 196 slips thereby effectively disengaging gear 202 from further driving the erecting arm. With gear 202 disengaged, shaft 188 is further rotated in a counter-clockwise direction to rotate cam 138 through gears 194, 184 and 139. As cam follower end 136 follows the peripheral surface of rotating cam 138 it is pushed outwardly to pivot plate 118 and thereby move hook member 120 outwardly to its extended position shown in dotted lines in FIG. 15 wherein it clears the forward end 122 of applicator 14. Further rotation of cam 138 causes the follower end 136 to retract under the influence of spring 140 thereby moving plate 118 back to its retracted position moving hook member 120 into capturing engagement with applicator end 122.

With the applicator 14 now engaged by hook member 120, the drive to shaft 188 is reversed thereby raising the erecting arm 112 and the engaged applicator to the substantially upright or erected position shown in FIG. 12. The erected position is established by the pin 174 on arm 112 abutting against the end of the curved guide member slot 172. When arm 112 is so arrested, the clutch mechanism will disengage the driving action of gear 202. Again, when arm 112 is pivoted upwardly, the cam gear 139 pivots but there is no relative motion between cam 138 and cam follower 136 so that hook member 120 remains in its retracted position gripping the top end 122 of the applicator 14.

With the applicator erecting arm assembly in its upright raised position of FIG. 12, the applicator 14 is located outside of the cone of light transmitted by lens 108 thereby permitting exposure of film component 12 supported on surface 94.

Following exposure, the applicator erecting mechanism maintains the applicator 14 in its upright position and the pick mechanism 98 is actuated effecting unsealing of the marginal seals 28, 30 and 32. Pick drive shaft 68 is rotated in a counterclockwise direction to drive the pick slide members 154 rearwardly. In response to this motion, the rearwardly facing pick fingers 160 travel through the corresponding notches 76 in the rear wall section 33 of the raised applicator and engage and exert a rearwardly push on the overlying portions 78 on the opposite wall section 31 of cover sheet 20. The film component 12 is prevented from sliding rearwardly in responsive to the force exerted by fingers 160 by its abutment with the trailing end rib 106. The applicator 14 is retained in its upright position by the engagement of hook member 120. Thus, the rearwardly pushing or urging force applied by the pick fingers 28 pushes the rearwardly facing wall section 31 of cover sheet 20 away from the opposite wall section 36 closest to erecting arm 112 creating a shear force within the bond between the two wall sections which is effective to strip or peel the marginal seals 28, 30 and 32.

In addition to unsealing the marginal seals, the rearwardly advancing pick fingers 160 begin to deploy the unsealed cover sheet and move it toward its extended position. As best shown in FIG. 13 when the pick slide members 154 are in their rearwardmost position the wall sections 31 and 33 of sheet 20 form a tent-like structure over surface 16. During such rearward movement, the fold line end 122 remains in engagement with hook member 120. During the course of rearward movement of the slide members 154, the lower end of the curved guide 170 is pick up and moved rearwardly by slide member 154 so as to pivot the erecting arm 112 downwardly toward support surface 94 thereby also pushing down on the wall section 30 of cover sheet 20. In this manner the urging of erecting arm 112 also helps to move cover sheet 20 toward its extended position.

With the cover sheet 20 in its partially deployed position of FIG. 13, the drive to the pick mechanism is reversed to drive the slide members 154 forwardly, as best shown in FIG. 14, and fingers 162 slide into the junction between the leading end of the applicator sheet 20 and the leading end of film component 12, and push on the joint therebetween to advance the film unit 10 up over the short rib 104 and into the bite of the pressure applying rollers 100 and 102. The rollers are driven in a manner to effect advancement of the two film unit elements therebetween, thereby pressing the presoaked pad 24 on the interior surface of the extended sheet 20 into good contact with the surface area 16a of film component 12 to effecting wetting of the image area.

Those skilled in the art will appreciate that the rollers 100 and 102 do not have to be manufactured to highly precise tolerances in that their function is merely to press the two film unit elements together to establish good contact therebetween rather than also have to spread the processing fluid in a precise thickness.

Because the impervious sheet 20 is opaque and forms a back cover sheet for the exposed film unit, film unit 10 may be advanced from the pressure rollers directly into an actinic radiation atmosphere without causing further exposure of film unit 10. Passage through the pressure applying rollers also presses the peripheral areas of the cover sheet 20 into good contact with the facing peripheral areas of the film component surface 16 to establish a marginal seal therebetween as described earlier. Depending on the type of film construction, the sheet 20 may be stripped from film component 12 following processing or, it may be left in place permanently to serve as a cover sheet if the image is viewed through the opposite side of the film unit.

The liquid holding means in application may take forms other than a liquid soaked absorbent pad 24. For example, pad 24 may be replaced with a layer of microcapsules, each enclosing a drop of liquid processing composition, adhered to surface 27. In response to advancing the film unit through the pressure applying rollers, the microcapsules rupture thereby releasing the liquid to effect wetting of surface area 16a.

Since certain changes made be made in the above-described film unit and processing apparatus without departing from the spirit and scope of the invention involved herein, 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.