Film Canister With Independent Sealing Surfaces

Reference is made to commonly assigned application Ser. No. 08/455006 (now U.S. Pat. No. 5,655,658) ›Attorney Docket No. 71730!, entitled: FILM CANISTER filed concurrently herewith in the names of Alex Saveliev, Victoria L. Decker and Michael W. Didas, and which is assigned to the assignee of this application.

1. Field of the Invention

The invention relates generally to the field of photography. More specifically, the invention relates to an improved moisture and light resistant container for a photographic film cartridge.

2. Background of the Invention

Film containers or canisters are known for storing film cassettes or cartridges having an exposed or unexposed film contained within the cassette. Previously, a typical container for a 35 mm film cassette comprised an open cylindrical receptacle, commonly referred to as a "can", for storing the film cassette, and a press-on cap or cover which covers the opening to the can to provide a moisture-proof light seal. An example of such a container is disclosed in U.S. Pat. No. 4,639,386, granted Jan. 27, 1987. The can and the cap are usually molded from a plastic material, e.g., black high density polyethylene (HDPE), which is moisture proof, opaque, and chemically inert.

A cover for a film canister serves two primary functions. First, the cover must seal to the can body to prevent moisture and light from being transmitted through the opening of the can in order to protect a stored film cartridge. Second, the cover must also be releasably attachable and be retained by the can.

There are two types of 135 film container covers generally found in the art: plug-type and snap-type covers. A snap-type cover seals to the body of the can by the mating of cover surfaces to internal surfaces of the can. Such a cover is then retained using features which are external to the can outside diameter. A plug-type cover, on the other hand, provides seal and retention features that are both located inside the can without requiring any overhanging features external to the can, with the possible exceptions of those features required only for ease of opening the cover, such as a thumb tab.

In plug-type covers, such as those described in U.S. Pat. No. 4,844,961, among others, the seal and retention features of the cover are combined, such as by tightly fitting a radial bead of the cover with a corresponding groove in the interior of the can. Though relatively effective retention of the cover to the can is provided, the above design leaves little room to separately optimize either the sealing and retention characteristics of the container without sacrificing the remaining characteristic.

The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, there is provided a cylindrical container for a photographic film cassette comprising a body having an interior sized to retain said film cassette and an open end;

a cover for engaging the open end of said body;

means for releasably securing the cover to said body; and

means for sealing the interior of said body from moisture and dust when said cover is secured by said securing means to said body, is characterized in that:

said cover includes a circumferential rib member for engaging an inner recessed portion of said body adjacent said open end to releasably secure said cover to said body, and a radial sealing surface for engaging an inner radial sealing surface of said body, wherein the radius of said inner radial surface is less than the radius of the cover sealing surface.

According to another aspect of the present invention, there is provided a cylindrical container for a photographic film comprising a body and a cover having an engageable portion for engaging an open end of said body, characterized in that:

said engageable portion includes a circumferential rib member for engaging a recess disposed along an inner radial wall of said body for retaining said cover to said body, and said body includes a inner wall portion having a first radial sealing surface for engaging a second outer radial surface of said engageable portion wherein the radius of said first sealing surface is greater than the radius of the second sealing surface relative to a center axis of said container to tightly seal said container from moisture, light, or dust.

An advantageous aspect of the present invention is that a container is provided which separately provide sealing and retention features, thereby maximizing the benefits available to each. The ability to optimize the sealing and retaining characteristics of the container provides an easily sealable container having a modest release force for a user, and in which the seal is efficient in insulating a stored film cassette from environmental effects such as dust, moisture or light.

These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following Detailed Description of the Invention and appended claims, and by reference to the accompanying drawings.

FIG. 1 is a perspective view of a film canister in accordance with a preferred embodiment of the present invention;

FIG. 2 is the perspective view of FIG. 1 showing the film canister with the cover removed;

FIG. 3 is the perspective view of the film canister of FIG. 2 rotated clockwise by 30 degrees;

FIG. 4 is an enlarged perspective view of the cover which is shown in the preceding FIGS. 1-3;

FIG. 5 is a cross sectional view of the film canister of FIGS. 1-4 showing the separate sealing and retention features of the container/cover interface;

FIG. 6 is an enlarged and exaggerated cross sectional view of the film canister taken at section 6--6 of FIG. 5 showing in particular the sealing features of the present invention; and

FIG. 7 is the enlarged sectional view of FIG. 6 of the film canister, showing in particular, the retention features of the present invention.

The invention is hereinafter described according to a preferred embodiment. It should be readily apparent, however, that the foregoing description should not be limited to the specific embodiment described.

Referring now to the FIGURES, and specifically to FIG. 1, there is shown an elevated perspective view of a reusable film canister 10 having an elliptical cross section for containing a similarly shaped film cartridge (not shown). The canister 10 includes a body 12 and a cover 14, each being made from a moisture resistant plastic material, e.g. high density polyethylene (HDPE), and formed in an injection molding process as is commonly known in the field. Most preferably, the cover 14 and the body 12 are made from the same material.

FIGS. 2 and 3 illustrate the same perspective view of FIG. 1, showing the canister 10 with the cover 14 removed, revealing that the cover 14 is a plug-type cover, and the body 12 includes an interior cavity 44 which is sized and configured for storing a film cartridge (not shown), the cavity being defined by a circumferential inner side wall 50. The canister 10 is defined by a top necked portion 41 having an open end 46 for interfacing with the cover 14, FIG. 7, as described in greater detail below. The body interior 44 is sized to retain a film cassette (not shown).

Referring now to FIGS. 2-4, and as noted the cover 14 is of the plug-type. The cover 14, having an elliptical cross section, is further defined by an upper lid portion 24 and a lower engaging portion 26. The upper lid portion 24 is defined by outermost dimensions which are slightly greater than that of the body 12, see FIG. 5, as well as a thumb tab 30, commonly known in the art to provide ease in repeatably removing the cover 14 from the body 12. The upper lid portion 24 also includes a generally flat top surface 32. The provision of a flat top surface 32 allows the labeling of the contents of the container either by a handwritten or preprinted label (not shown) which can be affixed thereto.

Referring to FIGS. 4-7, the lower engaging section 26 of the cover 14 fits within the top necked portion 41 of the body 12. The engaging portion 26 includes a substantially vertical (according to the embodiment shown) inner radial sealing surface 36 which is circumferentially disposed about axis 56 to correspond to the elliptical cross section of the cover 14. Below the sealing surface 36, a circumferential rib member 38 is provided, which extends radially outwardly beyond the radius defined by the cover sealing surface 36. A depending end 37 of the lower section 26 is tapered inwardly from the rib member 38.

According to the described embodiment, the rib retaining member 38 extends radially outward a distance of about 0.002 to 0.006 inches (0.51 to 1.52 mm) from the radius of the cover sealing surface 36.

Referring to FIGS. 5-7, the top necked portion 41 of the body 12 at the open end 46. FIG. 3, of the body 12 is defined by an oversized recessed portion 52 along the circumferential inner side wall 50 that extends radially outwardly about 0.006 to 0.010 inches (1.52 to 2.54 mm) from the radius of the inner side wall 50 to accommodate the rib retention member 38 of the engaging portion 26 of the cover 14. Above the recessed portion 52, a second sealing surface 45 is defined having a radius as measured from the center axis of the body 12 and which is less than the radius of the cover sealing surface 36, which is measured from the center axis of the cover 14. In this embodiment, as noted above, each of the body and cover geometries are defined by elliptical cross sections. However, other contours are easily imagined which provide a radial interference between sealing surfaces 36, 45. When assembled, the cover center axis is coincident with the center of the body, therefore, the radii of the sealing surfaces 36, 45 are measured from the same point, that is from a common vertical center axis 56. Preferably, a radial interference of about 0.010 to about 0.020 inches (2.54 to 5.08 mm) between the two sealing surfaces 36, 45 is sufficient to seal at a Moisture Vapor Transmission Rate (MVTR) of about 0.24 mg/wk Torr. The radial overlapping is clearly illustrated in FIG. 6, in order to show the sealing features of the container 10.

The described design allows the seal area defined by the cylindrical sealing surfaces 36, 45 between the cover 14 and the body 12 of the container 10, respectively, to provide radial interference and maximum surface area to surface area contact in order to provide adequate MVTR protection, while also independently and uncomprisingly allowing the cover 14 to be retained by the body 12 due to the interface between the rib member 38 and the oversized groove 52.

Most preferably, and now referring to FIG. 4, the rib retaining member 38 can be made discontinuous by locally removing a small circumferential vent portion. In the present embodiment in which the container 10 is provided with an elliptical cross section, it is preferred that the locally removed vent portion 42 be provided along the minor axis of the defined ellipse. The vent portion 42 provides a path for internal pressure to be vented from the interior of the container 10, causing the cover 14 to remain retained at higher altitudes (equivalent to 33,000 feet above sea level) without significant increases in opening force, even after applying an opening force at sea level after the container has been at higher altitudes. The inner wall is provided with a chamfer 54 preferably to allow ease in placement of the cover 14 onto the open end of the body 12.

10 film canister

12 body section

14 cover

24 upper lid portion

26 lower engaging section

30 thumb tab

32 flat top surface

36 seal surface

37 depending end portion

38 retaining rib member

41 top necked portion

42 vent

44 cavity

45 seal surface

46 open end

50 circumferential side wall

52 recess

54 chamfer

56 vertical axis

The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected without departing from the scope of the invention; for example, it should be readily apparant that the container described, having separate sealing and retaining features which can be optimized depending on the product being stored therein, should not be limited to an elliptical cross section; that is, a container having similar features which can be provided for a container having a circular or other cross section.