US3613537A

US3613537A - Photographic film pack

Info

Publication number: US3613537A
Application number: US841864A
Authority: US
Inventors: David A Frost
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1969-07-15
Filing date: 1969-07-15
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19
Also published as: CH517955A; AU1753470A; BE753416A; FR2055081A5; DE2035124A1

Abstract

A film pack containing a plurality of film units in which a diffusion transfer process is utilized to form photographic images and each film unit comprises a photosensitive sheet which is connected to an image-receiving sheet by means for moving the photosensitive sheet, after exposure, into superposition with the image-receiving sheet and thereafter withdrawing the two sheets in superposed relation through an opening in the end of the pack to spread a processing liquid between the two sheets is provided with an improved restraint mechanism for restraining movement of the image-receiving sheet until the photosensitive sheet is moved into superposed relation therewith. This restraint mechanism comprises a deformable projection extending from at least one edge of the image-receiving sheet which engages the end of a wall forming a part of the pack and holds the image-receiving sheet against movement until the projection is deformed by the pulling force required to withdraw the two sheets from the pack in superposed relation.

Description

United States Patent Inventor David A. Frost Rochester, N.Y. App]. No. 841,864 Filed July 15, 1969 Patented Oct. 19, 1971 Assignee Eastman Kodak Company Rochester, N.Y.

PHOTOGRAPHIC FILM PACK 12 Claims, 10 Drawing Figs.

U.S. Cl 95/13, 95/ 19, 96/76 Int. Cl G03b 17/50 Field of Search 95/13, 19;

References Cited UNITED STATES PATENTS 3,002,437 10/1961 Eloranta 95/13 3,294,538 12/1966 Downey 96/76 3,357,330 12/1967 Murphy 95/13 3,479,184 11/1969 Land et al Attorneys-Walter O. Hodsdon and Karl T. Naramore ABSTRACT: A film pack containing a plurality of film units in which a diffusion transfer process is utilized to form photographic images and each film unit comprises a photosensitive sheet which is connected to an image-receiving sheet by means for moving the photosensitive sheet, after exposure, into superposition with the image-receiving sheet and thereafter withdrawing the two sheets in superposed relation through an opening in the end of the pack to spread a processing liquid between the two sheets is provided with an improved restraint mechanism for restraining movement of the image-receiving sheet until the photosensitive sheet is moved into superposed relation therewith. This restraint mechanism comprises a deformable projection extending from at least one edge of the image-receiving sheet which engages the end of a wall forming a part of the pack and holds the image-receiving sheet against movement until the projection is deformed by the pulling force required to withdraw the two sheets from the pack in superposed relation.

' 3,613,537 SHEET 10F 3 minimum 191911 DAVID A. FROST INVENTOR.

fi/I/Z ATTORNEYS SHEET 2 CF PATENTEDUEI 1 9 1971 IN VENTOR.

A TTOR/VE'YS 04 W0 A. FROST PATENTEUUU 19 3,613.53 7

SHEET 3 OF 3 DAV/0 A. FROST INVENTOR.

A TTORNE Y8 PI-IOTOGRAPHIC FILM PACK This invention relates to photographic assemblies in which a diffusion transfer process is utilized to form photographic images, and particularly to such assemblies in which a number of multilayered photographic film units are individually stored in a film pack in flatwise relation rather than in roll form.

Film packs of the type mentioned may take the form of a generally flat, elongated container having an exposure aperture in the form of a rectangular opening in one longitudinal wall through which light from the scene being photographed can be focused, and an exit opening in one transverse end wall through which a film unitcan be withdrawn fromthe container subsequent to the exposure for processing by the camera. Each film unit includes a photosensitive sheet and an image-receiving sheet and the format of each film unit within the pack is such that the sheets are in superposed relation with the active surfaces of each facing in the direction of the exposure aperture. A pressure plate is located between the sheets to separate them and to urge the photosensitive sheet into a plane that coincides with the focal plane of the camera into which the film pack is inserted. Web means interconnect the two sheets and are cooperable with the pressure plate so that the photosensitive sheet can be moved longitudinally relative to the container after exposure until its exposed surface is positioned in registration with and adjacent the active surface of the image-receiving sheet. In this condition the two sheets are in what is referred to as contacting registration and the introduction of a processing fluid between the sheets effects a transfer of the exposed latent image on the photosensitive sheet to a positive image on the image-receiving sheet. Such an introduction of a processing fluid takes place when both sheets are longitudinally moved as a unit through the exit opening of the container and between a pair of pressure-applying members in the camera. The construction of the film unit is such that initial movement of the two sheets as a unit through the pressure rolls fractures a pod holding the processing fluid and attached to the film unit. Upon continued movement of the sheets as a unit through the pressure rolls the processing fluid is spread in a controlled uniform thickness between the sheets and the diffusion transfer process takes place outside of the camera. To facilitate removal of the unit from the film pack the exit opening of the container is made large enough to allow free longitudinal movement of the two sheets in contacting relation into and through the exit openmg.

One of the problems encountered with film packs of the type described is that frequently one obtains a so-called misregistered positive containing only a portion of the image on the photosensitive sheet or negative. In other words, part of the positive is blank. Additionally, one sometimes obtains a posi tive image on the receiving sheet which is blurred in whole or in part.

These two above-mentioned problems arise because the negative image on the photosensitive sheet is not in contacting registration with the image-receiving sheet before the processing fluid is introduced between the superposed sheets. This misregistration can occur by reason of the fact that movement of the photosensitive sheet toward a position in contacting registration with the image-receiving sheet tends to longitudinally displace the image-receiving sheet into the exit opening. The positive image obtained in such a case is out of registration by the amount the image-receiving sheet moved during movement of the photosensitive sheet to the position where it should be in contacting registration with the imagereceiving sheet. Sometimes, the two sheets, while initially out of register when the processing fluid is introduced between them, move into registration while the film unit is being withdrawn from the container. This results in a blurred print since the processing fluid is already between the sheets when relative movement between them occurs.

It follows then that in the operation of an integral processing film unit of the type described it is necessary that the receiver sheet not enter the camera rollers until the negative has been registered with it. The prior art has used several different approaches in an attempt to solve this problem. For example, in a commercially available film pack the restraint to premature advance of the receiver sheet or positive is achieved by means of a foam rubber pad fastened to the cover of the film pack near the exit opening. This pad is forced into frictional contact with the back of the outermost receiver sheet by a cam on the camera back and friction tends to hold the receiver in place. This construction is shown in French Pat. No. 1,407,412. Means comprising restraining fingers attached to the container cover and engaging the leading edge of the outermost receiver are described in U.S. Pat. No. 3,002,437.

The primary object of the present invention is to provide an improved means to restrain the image-receiving sheet of a film unit in a film pack of the type described against premature movement as its associated exposed photosensitive sheet is moved into contacting registration therewith.

Another object is to provide a restraint means of the type described which is part of the film pack itself and does not depend upon insertion of the film pack into a camera to become operative.

A further object is to provide a restraint means which requires no additional parts in either the pack container or the film units used therein, and one which is adaptable to economical high-speed automatic fabrication and assembly of both the film units and the packs containing a plurality of such film units.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its methods of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings in which:

FIG. 1 is a fragmentary perspective view of a photographic film unit embodying the present invention;

. FIG. 2 is a fragmentary perspective view, on an enlarged scale, showing how a photographic film unit embodying the present invention cooperates with the pressure plate of a film pack to restrain the image-receiving sheet of the film unit against premature movement;

FIG. 3 is a plan view, on an enlarged scale, of an embossed film trap constructed in accordance with a preferred embodiment of the present invention;

FIGS. 4, 5 and 6 are longitudinal sectional views of a film pack and camera combination, with the pack holding a single film unit, and illustrating the relative positions of the components of the film unit as it is withdrawn from the pack and the camera for processing an exposed film;

FIGS. 7 and 8 are partial plan views of film traps having restraining means of different configuration in accordance with the present invention; and

FIGS. 9 and 10 are partial longitudinal sectional views of a film pack, on an enlarged scale, constructed in accordance with other embodiments of the present invention.

Briefly, according to the present invention, premature advance of the receiver sheet or positive from the film pack during longitudinal movement of the exposed photosensitive sheet or negative into contact registration therewith is prevented by providing deformable projections on the positive which are arranged to engage the ends of the sidewalls of the pressure plate in the film pack and thereby restrain premature longitudinal movement of the positive during the time the negative is being pulled into contacting registration therewith. The resistance to deformation of these projections is such that, after the negative has been moved into registration with the positive and a direct pull is applied to the leader connected to both the positive and negative, these projections will become deformed to an extent such that they will disengage from the ends of the sidewalls of the pressure plate and the positive and negative will move together through the pressure rolls of the camera. These deformable projections may comprise plastic strips fixed to the positive and arranged to extend slightly beyond the longitudinal edges thereof, or they may comprise scalloped or serpentine edges formed in the end(s) of the plastic trap means disclosed in copending US. application Ser. No. 84l,865 filed July 15, 1969 of which I am a coinventor.

Referring now to FIG. 1, a film unit of the type to be used in this film pack is shown partially folded to the condition it will assume when placed in the pack. Only so much of the film unit is shown herein as is necessary to a complete understanding of the present invention, since reference can be had to the above-noted copending application for a more complete description of the film unit and the components making up the same. Basically, the film unit designated comprises a generally rectangular photosensitive sheet 11, hereinafter referred to as the negative, and a second or print-receiving sheet 12, hereinafter referred to as the positive. Both of these sheets comprise a support which is opaque to light actinic to the photosensitive material of the negative.

Attached to the leading edge of the negative is a leader sheet 14 having a first section 15 approximately equal in width to the negative and having a tapered end section 16. The transverse edge of the first section 15 is coupled to the leading edge of the negative, as indicated at 17, and a rupturable fluidcontaining pod 18 is mounted on first section 15 ahead of the leading end of the negative. The second sheet, or positive, 12 is mounted on a carrier sheet 19 having an intermediate section 20 approximately equal in width to the positive end having a generally rectangular opening 21 therein defining the area of the positive in which the positive image formation occurs. Those portions of the intermediate section 20 bordering on opening 21 provides a mask for defining the area of the image transferfrom the negative to the positive. Carrier sheet 19 includes a leading end section 23 having a tapered end section 24 similar to tapered'end section16 and secured thereto behind the leading end of the tapered end section 16 as indicated at X." Tapered end section 16 and tapered end portion 24 cooperate to define the leading end section of the film unit which is advanced between the pressure-applying members in the camera. Detachably adhering to the tapered end section 16 of the leader sheet 14 behind the leading edge thereof is a relatively narrow pull tab 60.

The length of the leader sheet 14 between the leading edge of the negative 11 and the point of attachment of the leader sheet to carrier sheet 19 is substantially equal to the length of the carrier sheet 19 between its point of attachment to the leader sheet and the leading edge of the positive 12. It is by virtue of this arrangement that the negative and positive are capable of being brought into superposed contacting registered relation before and during the processing of the film unit.

The trailing end of the negative or the trailing end of the positive may carry any one of a number of suitable means for trapping the excess processing fluid, but since a trap of the type disclosed in the above-noted copencling application can be modified to provide a restraining means for premature movement of the positive in accordance with a preferred embodiment of the present invention, that is the type of trap illustrated in the drawings. This trap, generally designated at 25, comprises a trailer sheet 26 of embossed plastic sheeting secured to the face of the trailing end of the carrier sheet 19 along a line indicated at 27. When thenegative 11 is moved into superposed relation with the positive 12 for processing, the embossed trailer sheet 26 is superposed with the trailing end of the negative to provide a volume or space for collecting and retaining excess processing fluid.

A plurality of film units 10 are adapted to be packed in a container or pack, generally indicated at 38, see FIG. 4, so as to be individually withdrawn therefrom in succession for processing. This container comprises a generally parallelpiped-shaped box 39 open at the top and having a forward wall 40, upstanding sidewalls 41, a trailing end wall 42, and a leading end wall 43. Forward wall 40 is provided with a generally rectangular exposure aperture 44 through which the photosensitive sheets 11 of the film units carried within the container are exposed. Leading end wall 43 extends only part way of the depth of the box so as to provide a passage 45 at the leading end of the container through which the film units can bewithdrawn one at a time. The top of the container is closed by a metal cover 46 having flanges 47 turned down along the sides and rear end to slidably engage the sidewalls 41 and the trailing end wall 42 of the box when the cover is slid endwise onto the top of the container after a plurality of film units are loaded into the box. lnsertable into the top of the container is a generally flat, rectangular pressure plate 50 having a rolled end section 52 and upstanding lateral flanges 53 disposed-adjacent the sidewalls of the container. The cover 46 of the container is provided with springtfingers'Sfi biased inwardly for engaging the top of the flanges 53 and urging the pressure plate 50 toward forward wall 40 to retain the photosensitive sheet or negative 11 in a plane for exposure.

To load a plurality'of film units 10 into the containerv the cover 46 is first removed and the pressure plate 50 is removed. A plurality (usually 8 or 12) film units are then wrapped around the pressure plate 50 in the manner in which one is shown in FIG. 4 for simplicity, and then the pressure plate 50, with the film units arranged thereon, is dropped into the top of the container and the cover 46 is slipped onto the top of the container to close the same. As shown, the film unit 10 is arranged with its negative 11 and positive 12 in overlying relation on opposite sides of the pressure plate 50 with the photosensitive surface of the negative facing outwardly toward the exposure aperture 44 and with the image-receiving surface of the positive 12 facing in the same direction. As clearly shown in FIG. 4, the leader sheet 14 is bent back upon itself around the rolled end 52 of the pressure plate 50 and the carrier sheet 19 is folded in a Z" shape with the two parallel legs of the Z representing the regions sealed to the leader l4 and the leading end of the positive, respectively. While, as disclosed in the above-noted copending application, the pull tab 60 of the film units may be folded back upon themselves to lie within the container, .or extend therefrom into the camera when the container is mounted therein, when a particular film unit is ready for exposure and/or processing its pull tab 60 will extend from the container and to the outside of the camera where it can be grasped to withdraw the film unit for processing.

To understand the need for, and the results obtained by the restraint means for preventing premature advance of the positive according to the present invention, a film pack containing one film unit is shown in FIGS. 4-6in combination with a camera of the type which is to be used with'and the components of the film unit have been shown in successive positions they will assume when the exposed film unit is processed. Only one film unit 10 has been shown in the container 38 in order to facilitate an understanding of the manipulation of the film unit during processing, and only so much of the camera has been shown as is necessary to understand the cooperation between the camera and the film pack.

The rear of the camera, not shown, has a compartment 120 into which a film pack is to be inserted with the negative 11 of the outermost film unit located in the focal plane of the camera lens, not shown. The compartment 120 is closed by a hinged cover, not shown, after the film pack is inserted thereinto, and the end wall of the camera includes a pair of openings 74 and 78. Carried by the hinged cover are a pair of

pressure rollers

75 and 76 which are separable but which are spring loaded toward one another. To provide a gap between the

rollers

75 and 76 through which the leading end 16 of the leader 14 can pass, as described below, the ends of the rollers may be provided with shoulders which come into rolling engagement and provide such a gap. When the cover is closed the nip between these pressure rollers is in alignment with the opening 74 in the end wall of the camera, and a tangent to the top of guide 80 in the camera body will pass into the nip between the rollers.

When a film pack is loaded into the camera and the first film unit in the pack is ready'for exposure the components of the film unit will assume the position shown in FIG. 4.'It will be seen that the pull tab 60 extends around the outside of the pressure roller 76 and through opening 78 to the outside of the camera where it can be grasped by the operator. The remainder of the components of the film unit are within the container 38 with the photosensitive surface of the negative I] pressed into the focal plane of the camera by the pressure plate 50 and in register with the exposure aperture 44 in the front wall of the container; the positive is on the other side of the pressure plate 50 in register with the negative but with its image-receiving surface facing the pressure plate; the leader sheet 14 extends around the rolled end 52 of the pressure plate and tapered end portion 16, along with the folded carrier sheet 19 lie between the positive 12 and the pressure plate 50.

After the negative is exposed, the pull tab 60 is grasped by the operator and is sharply pulled in the direction of the arrow. This pulls the leader [4 toward the exit opening 45 in the container and the negative 11 to which it is sealed moves around the rolled end 52 of the pressure plate 50 toward contacting registration with the positive 12. As the negative moves, that portion of carrier strip 19 connected to the leader unrolls so that the diagonal of the Z fold therein is shortened and one of the parallel legs is accordingly lengthened as shown in FIG. 5. When the pull tab 60 has been pulled sufficiently far, the carrier strip 19 becomes very nearly straightened out; or the diagonal of the 2" fold has practically vanished, as shown in FIG. 5. At this time, the tapered end section 16 of the leader 14 has been moved between the

pressure rollers

75 and 76 to partially extend from the camera and the pull tab 60 has, or is just about to, become detached from the leader 14 by reason of a peeling action on the seal between the two caused by the divergent path of the pull tab in moving around the outside of roller 76. The tapered end 16 of the leader 14 is now grasped by the operator and this results in a direct pull on the negative causing it to be moved relative to the positive and into contacting registration therewith. When the Z fold in the carrier strip 19 straightens out so that a pull on the leader [4 acts directly on the positive as well as the negative, the positive and negative are in contacting registration and the pod 18 has been moved between the

pressure rollers

75 and 76 and has been ruptured, see FIG. 6. A continued pull on the leader 14 will move the negative and positive together between the pressure rolls in contacting registration and will spread the processing fluid from pod 18 uniformly between and along the length of the positive and negative for processing the same.

The fact that the exit 45 of the pack must allow free longitudinal movement of the positive and negative as a unit gives rise to the problem of constraining premature advances of the positive to insure accurate contact registration between the positive and negative before the two are moved as a unit between the pressure rollers. If the positive is not constrained against longitudinal movement during the first step described above, namely the displacement of the leading edge of leader l4 externally of the camera, which is accompanied by longitudinal displacement of the negative until the latent image thereon is in contacting registration with the positive, it has been determined that movement of the negative toward its position in contacting registration with the positive tends to urge the positive in the same direction as the direction in which the leader 14 moves. When this occurs and the pull tab 60 becomes detached from the leader 14, the leading end 16 of the leader may extend the normal amount through the

rollers

75 and 76 indicating that the negative 11 has been moved to the position where it should be registered with the positive, but since the positive has been advanced well into the exit opening 45 by frictional drag between it and the carrier sheet I9 during its unrolling, under this condition the negative will not be brought into proper registration with the positive. Now when the leader 14 is grasped and pulled the positive and negative will either be pulled through the pressure rollers out of registration, as the result of which a part of the picture will be lost, or, if the carrier sheet has not completely unfolded due to the premature advance of the positive, a relative movement between the negative and positive can occur as they are pulled through the rollers so that the transferred positive image will be blurred.

It is to prevent this premature advance of the positive that the present invention is concerned. According to the present invention, means for restraining premature movement of the positive comprises fixing deformable projections to the positive, or a part fixed thereto, which extends beyond the edges of the positive and engage the ends 49 of the upstanding flanges 53 on the pressure plate 50 to prevent longitudinal movement of the positive toward the exit 45 in the pack until registration between the negative and positive has been accomplished. Immediately after registration of these two parts is obtained, and a pull is applied to the leader 14 of the film unit, the projections are deformed substantially to become disengaged from the ends of the flanges of the pressure plate so that the positive then moves through the exit 45 with the negative.

In accordance with a preferred embodiment of the present invention, this restraining means is provided by cutting the ends of the embossed plastic trap 26 in a serpentine or scalloped pattern as shown in FIG. 3. The overall width of the trap 26 is greater than the distance between the flanges 53 of the pressure plate so that the scalloped pattern forms deformable projections extending beyond each edge of the positive. The general shape of the trap and its relationship to the sidewalls of the pressure plate when the film units are loaded into the pack is shown in FIG. 2.

Since both the positive 12 and the trap 26 are sealed face to face to the carrier sheet 19, as fully disclosed in the abovenoted copending application Ser. No. 84l,865 filed .luly I5, 1969, the trap and positive act as a single sheet. When the pull tab 60, leader l4, and negative 1] advance, the positive may move forward a small fractionrof an inch before the leading ones of the projections at the ends of the trap engage with the ends of the flanges of the pressure plate. The force required to deform the projections 150 on the end of the trap is greater than that transmitted to the positive 12 by moving negative 11 or leader sheet 14 when the pull tab 60 is pulled. Thus, the positive will move no further toward the exit 45 until the negative 11 is brought into contacting register with the positive. The next step of pulling directly on the leader sheet 14 transmits a moving force directly to the positive as described above. This force is sufi'icient to defonn the projections 150 on the ends of the trap so that they will be released from the ends of flanges 53 of the pressure plate 50 and as a result, immediately after registration, the negative and positive will move through the exit 45 and between the

pressure rollers

75 and 76 together. The force required to accomplish this deformation of the projections 150 is less than that required to rupture the carrier sheet 19 or the seals between the carrier sheet and either the leader 14 or the trap 26.

The proper functioning of this invention must be related to the material used for the trap 26. Obviously, a tissue paper would not have enough rigidity to provide the necessary restraint. Projections from a steel sheet 0.010 inch thick would not deform easily enough to permit motion of the trap after the carrier sheet 19 is straightened out. Polystyrene sheeting 0.005 inch thick, cut as shown in FIG. 3, has been found to be perfectly satisfactory, and since this material has also been found to be satisfactory as an embossed trap, see copending application Ser. No. 841,865 filed July 15, 1969, it is possible to make the present restraining means and the embossed trap from a single part. It can be reasonably expected that any other thin plastic sheeting, such as 0.005 inch thick cellulose acetate, 0.0055 inch thick cellulose acetate butyrate, found suitable for making an embossed trap as set forth in the noted copending application, would also be satisfactory for use as a restrainer means for the positive. Some variations in the shape of the pattern cut in the ends of the trap 26 would also be expected to work and FIGS. 7 and 8 show at 150' and 150, two variations that should be satisfactory.

- If the traps 26 used are cut from a continuous web, a more economical procedure than blanking them out individually with a single die, the projections 150 at one end of the trap will correspond to indentations at the other end and vice versa, see FIG. 3. As a result, the leading projection on opposite ends of the trap which first engage the ends of the sidewalls 54 of the pressure plate 50 are offset. Accordingly, it has been found desirable to cut the flanges 53 of the pressure plate 50 to length with the same ofi'set so that engagement of the leading projection 150 on each end of the trap with its corresponding flange 53 will occur simultaneously. Although a plurality of projections 150 have been shown on each end of the trap, it is pointed out that a single projection at each end of the trap would probably serve the purpose since it is the leading one of the group which actually provides the restraining action when it engages the pressure plate. The use of two or more projections 150 on each end of the trap 26 is desirable to provide for those instances where during assembly of the film units on the pressure plate 50, and then the insertion of the pressure plate into the container, there occurs a shifting of the film units relative to the pressure plate which might cause the leading projections 150 to accidentally engage the face of the flanges 53 of the pressure plate rather than lying ahead of the end of said flanges to properly engage the same when the positive tends to be inadvertently advanced.

It has been found that sometimes when the pull tab 60 is pulled to advance the negative, and afn'ctional drag tends to advance the positive, that the trap 26 tends to rise up and ride over the ends of the pressure plate. The tendency for this to occur is most prevalent in the outermost ones of a full film pack (one containing as many as eight film units) because, as indicated in dotted lines in FIG. 9, the trap of the outermost of the film units will engage the ends of the flanges of the pressure plate quite close to the top thereof. Also, since the trap portions of the film units are adjacent the rolled end 52 of the pressure plate, and will overlie the bent back portions of the leaders 14 which carry the pods 18, they will be located at the thickest part of the pack, the thickness at this point being exaggerated by reason of the fact that the bent back portions of the leaders tend to expand rather than adhering to the rolled end of the pressure plate. As shown in FIG. 9 one or more spring fingers 160 formed in the cover 46 and projecting down into engagement with the traps 26 will help to insure that the traps will not ride up and over the ends of the flanges 53 of the pressure plate 50. This problem can further be attacked by slanting the ends of the flanges 53 as shown at 49' in FIG. 9. A foam rubber pad, not shown, on the inside of the cover located so as to push down on any trap which tends to rise up and over the ends of the pressure plate has been found to be equally effective. In FIG. 10 another arrangement to prevent this overriding is shown. Here the ends of the flanges 53 of the pressure plate 50 are notched as shown at 161 to leave a longitudinally projecting finger 162 which will overhang the traps of the film unit and prevent them from riding up and over the ends of the pressure plate due to inherent expansion of the bent back portion of the leaders 14 and/or a frictional drag tending to move the positive forward. Also, should it be found that striking 1 spring fingers 160 out of the cover 46 as shown in FIG. 9,

presents a light-leak problem, the equivalent of such fingers can be provided by merely embossing the cover as shown at 160' in FIG. 10.

While from the standpoint of ease in assembly and low-cost fabrication it is desirable to make the restraining means for the positive a part of the trap of the film unit as above described, the invention is not limited to such a construction. For instance, the restraining projections for the positive could be strips of suitable material attached to the carrier strip 19, or the positive 12 itself, to extend beyond the edge or edges thereof at a point ahead of the trap, for example, at the middle of the positive. Then the flanges 53 of the pressure plate 50 could be cut away at a point where these projections will be located when the film units are assembled onto the pressure plate so as-to provide end walls which the projections would engage to restrain premature advance of the positive in the same way as thedeformable projections do in the described preferred embodiment. One advantage which might be obtained from making the restrainer strip separate from the trap would be that a greater choice of material might be made available for each of these parts. For example, a certain material might be suitable for forming an embossed trap but it would not be satisfactory for use as a restraining means.

Should the positive 12 comprise a coated support made of plastic sheeting, e.g. cellulose acetate, cellulose acetate butyrate, polyester, having a thickness of 0.005 in. 0.007 in., as it could be, then the deformable projections could be made integral with the positive and a separate plastic strip adhered to the positive or its carrier sheet 19 for the purpose of providing these deformable projections would not be required.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A film pack comprising, in combination, a container having an opening at one end, at least one film unit within said container adapted to be withdrawn from said container through said opening, said film unit including a first sheet element, a second sheet element positioned apart from said first sheet element with its leading edge adjacent said opening; a separating member within said container slidably engaging said second sheet element and located between and separating said two sheet elements; means connecting said first and second sheet elements for moving said first element to said second element into superposition therewith and for thereafter withdrawing said sheet elements in superposed relation from the container through said opening, said opening being at least equal in width to said elements and having a depth sufficient to allow the passage of said film unit; and means fixed to the second sheet element positively engageable with said separating member to restrain said second sheet element against movement during movement of said first sheet element relative to said second sheet element only until said two sheet elements become superposed.

2. A film pack as defined in claim I, wherein said separating member includes an edge guide adapted to slidably engage one edge of said second sheet element, and wherein said lastmentioned means includes a deformable part carried by the trailing end of said second sheet element and projecting beyond the edge of said sheet element to engage the end of said guide.

3. A film pack as defined in claim 1, wherein said separating member includes at least one edge guide slidably confining an edge of said second sheet element, and wherein said last-mentioned means includes a thin sheet of plastic material carried by the trailing end of said second sheet, and including at least one deformable projection extending beyond the edge of said sheet element to positively engage the end of said edge guide and restrain movement of said second sheet until it is deformed by a pulling force applied to the film unit after said two sheet elements have been moved into superposed relation.

4. A film pack as defined in claim 1, wherein said separating member includes a pair of edge guides spaced apart to slidably confine the opposite longitudinal edges of said second sheet element; and wherein said last-mentioned means includes a strip of thin plastic material fixed to and extending transversely of the trailing end of said second sheet element and including at least one deformable projection on each end extending beyond the edges of said sheet element to positively engage the ends of said edge guides and restrain movement of said second sheet until they are deformed by a pulling force applied to the film unit after said two sheet elements have been moved into superposed relation.

5. A film pack as defined in claim 4, wherein the leading deformable projection on opposite ends of said strip of plastic material are offset from one another longitudinally of said sheet element, and wherein the ends of said edge guides are correspondingly offset so that engagement between the two leading projections and the ends of their respective edge guides will occur substantially simultaneously.

6. A film pack as defined in claim 4, wherein there is a plurality of film units within said container resulting in there being a plurality of second sheet elements in stacked relation slidably confined by the pair of edge guides on said separating member, and including means within said container for preventing the trailing endsof said second sheets from rising above the top of said edge guides where the deformable projections will not engage the ends of said edge guides to restrain longitudinal movement of said second sheet elements.

7. A film pack as defined in claim 6, wherein said last-mentioned means comprises sloping the ends of said edge guides in a direction away from open end of said container so that they overhang the deformable projections on the stack of second sheet elements.

8. A film pack as defined in claim 6, wherein said last-mentioned means comprises notching the ends of said edge guides to provide a finger on each one thereof which overhangs the defonnable projections on said second sheet elements.

9. A film pack as defined in claim 6, wherein said last-mentioned means comprises a resilient member on the rear wall of the container pressing down against the trailing end of the stack of second sheet elements.

10. In a film pack the combination with a generally flat elongated container having an exposure aperture in one flat wall and an exit opening in one end wall; a pair of sheets, a first of which has a light-sensitive coating on one surface and the second of which has an image-receiving coating on one surface; the sheets being longitudinally arranged in stacked relation in the container with the coating on the first sheet being in registration with the exposure aperture so that its coating can be photographically exposed; an elongated pressure plate within said container separating said two sheets and including a curved sheet-guiding surface on the end opposite said exit opening and edge-guiding members extending substantially at right angles from the sides of said plate to slidably confine the opposite longitudinal edges of said second sheet; web means coupling the leading ends of said two sheets including a manually operable pull tab by which said first sheet can be moved longitudinally around the curved sheet-guiding surface of said pressure plate toward a position in which its coated surface is in contacting registration with the coated surface of the second sheet, the exit opening being of such size and so located relative to the leading end of the second sheet that there is no impediment to longitudinal movement of the second sheet through the exit opening during longitudinal movement of the first sheet toward contacting registration with the second sheet, of means fixed to the trailing end of said second sheet engageable with the edge-guiding members of said pressure plate to restrain movement of said second sheet through said exit opening during longitudinal movement of the first sheet into contacting registration with the second sheet.

11. In a film unit adapted for manipulation within a housing divided into two compartments by a separating member and for withdrawal from said housing through an opening in the end thereof, said film unit comprising a first sheet element and a second sheet element adapted to be located within said housing on opposite sides of said separating member, and means for interconnecting said sheet elements so that said first sheet element can be moved within said housing into superposition with said second sheet element prior to moving with said second sheet element through said opening during withdrawal of the film unit from said housing, the improvement comprising:

deformable means on said second sheet element and projecting from at least one edge thereof for positively engaging said separating member to restrain movement of said second sheet element dunng movement of said first sheet element into superposition therewith and thereafter deforming to release said second sheet element for withdrawal from said housing in superposed relation with said first sheet element.

12. A film pack comprising in combination, a container having an opening at one end, at least one film unit within said container adapted to be withdrawn from said container through said opening, said film unit including a first sheet ele ment, a second sheet element spaced from and parallel to said first sheet element with its leading edge adjacent said opening; guide means within said container slidably engaging at least one edge of said second sheet element and confining it to longitudinal movement toward said opening; means connecting said first and second sheet elements for moving said first sheet element relative to said second sheet element into superposition therewith and for thereafter withdrawing both of said sheet elements in superposed relation from the container through said opening; a defonnable part fixed to said second sheet element and projecting beyond at least one longitudinal edge thereof and positively engaging said guide means to restrain said second sheet element against movement during movement of said first sheet element relative to said second sheet element until said two sheet elements become superposed after which it becomes deformed sufficiently to slide past said guide means to allow the second sheet element to move to and through said opening with said first sheet element.

Claims

2. A film pack as defined in claim 1, wherein said separating member includes an edge guide adapted to slidably engage one edge of said second sheet element, and wherein said last-mentioned means includes a deformable part carried by the trailing end of said second sheet element and projecting beyond the edge of said sheet element to engage the end of said guide.

6. A film pack as defined in claim 4, wherein there is a plurality of film units within said container resulting in there being a plurality of second sheet elements in stacked relation slidably confined by the pair of edge guides on said separating member, and including means within said container for preventing the trailing ends of said second sheets from rising above the top of said edge guides where the deformable projections will not engage the ends of said edge guides to restrain longitudinal movement of said second sheet elements.

8. A film pack as defined in claim 6, wherein said last-mentioned means comprises notching the ends of said edge guides to provide a finger on each one thereof which overhangs the deformable projections on said second sheet elements.

11. In a film unit adapted for manipulation within a housing divided into two compartments by a separating member and for withdrawal from said housing through an opening in the end thereof, said film unit comprising a first sheet element and a second sheet element adapted to be located within said housing on opposite sides of said separating member, and means for interconnecting said sheet Elements so that said first sheet element can be moved within said housing into superposition with said second sheet element prior to moving with said second sheet element through said opening during withdrawal of the film unit from said housing, the improvement comprising: deformable means on said second sheet element and projecting from at least one edge thereof for positively engaging said separating member to restrain movement of said second sheet element during movement of said first sheet element into superposition therewith and thereafter deforming to release said second sheet element for withdrawal from said housing in superposed relation with said first sheet element.

12. A film pack comprising in combination, a container having an opening at one end, at least one film unit within said container adapted to be withdrawn from said container through said opening, said film unit including a first sheet element, a second sheet element spaced from and parallel to said first sheet element with its leading edge adjacent said opening; guide means within said container slidably engaging at least one edge of said second sheet element and confining it to longitudinal movement toward said opening; means connecting said first and second sheet elements for moving said first sheet element relative to said second sheet element into superposition therewith and for thereafter withdrawing both of said sheet elements in superposed relation from the container through said opening; a deformable part fixed to said second sheet element and projecting beyond at least one longitudinal edge thereof and positively engaging said guide means to restrain said second sheet element against movement during movement of said first sheet element relative to said second sheet element until said two sheet elements become superposed after which it becomes deformed sufficiently to slide past said guide means to allow the second sheet element to move to and through said opening with said first sheet element.