Container for light-sensitive material

A container for light-sensitive material is folded from a blank of thin opaque material. The blank has four rectangular panels hingedly connected so as to be foldable to form a generally rectangular tube with four sides and two open ends. A cap associated with each end of the tube closes the container in a light-tight manner. Interlocking structure is associated with the hinge connections for forming a tortuous light path to inhibit any light leakage through the material at the hinge connection from reaching the contents of the container. Besides the light-locking effect of the interlocking structure, it enhances cartridge strength in that all edges, when folded up, are double thickness of material. The end caps of the container may be blanked with the side panels with a hinge connection between each end cap and one of the side panels. To prevent light leaks, ridges are formed on the side panel and the end cap to form a tortuous path for any light which leaks through the blushed area.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to dispensing containers for rolls of 
light-sensitive material. 
2. Description of the Prior Art 
Containers for dispensing unexposed photographic film or paper from a roll 
are well known in the art and generally are fabricated of heavy paper, 
paper board, fiberboard or corrugated paperboard, such as shown in U.S. 
Pat. No. 3,481,457, which issued Dec. 2, 1969 to D. D. Overton III et al. 
Some such containers are more economically made of thin, opaque plastic 
which may be thermoformed into shaped blanks of various desired 
configurations. After shaping, the blank is folded into a tubular 
configuration, such as shown in our commonly-assigned U.S. Pat. No. 
4,239,164, which issued Dec. 16, 1980. 
While thin plastic containers have many manufacturing economies and user 
advantages, the opaque material of which they are formed has an 
undesirable characteristic of thinning out when a corner is folded with a 
small curvature radius. This thinning out, commonly referred to as 
"blushing," may result in loss of opaqueness and light integrity at the 
corners. To prevent blushing, the container shown in the above U.S. patent 
utilizes curved corners of large radii and separate end caps supplied 
after the main container body has been formed. While this offers a good 
light-tight container for many uses, there are certain advantages to 
having a container with sharper edges and integral end caps. To this end, 
the present invention provides light protection for the contents of such 
containers even though blushing can occur. Besides the light protection 
feature, the invention also provides double material thicknesses at the 
corners for structural strength. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an improved container is provided 
for light-sensitive material. The container is folded from a blank of 
thin, opaque material. The blank has four rectangular panels hingedly 
connected so as to be foldable to form a generally rectangular tube with 
four sides and two open ends. A cap associated with each end of the tube 
closes the container in a light-tight manner. 
Because the blank material may blush when folded, interlocking structure is 
associated with the hinge connections for forming a tortuous light path to 
inhibit any light which may leak through the material at the hinge 
connection from reaching the contents of the container. The interlocking 
structure includes a ridge on the inner surface of one panel adjacent each 
hinge, the ridge surface being spaced from the associated hinge by a 
predetermined distance. A second ridge on the inner surface of the other 
panel adjacent each hinge is close to the hinge so that when the hinge is 
folded, whereby the panels are normal to each other, the ridges form a 
tortuous light path from the hinge to the interior of the container. 
Besides the light-locking effect of the ridges, they provide a very strong 
cartridge in that all edges, when folded up, are double thickness of 
material. 
The ridges extend inwardly of the panels and occupy volume within the 
container. This does not present a problem at the edges of the panels 
because the rolls within the containers do not extend into the corners of 
the containers. By tapering the ridges off toward the center of the 
panels, the diameter roll receivable in the container can be maximized. 
The end caps of the container may be formed integral with the side panels, 
with a hinge connection between each end cap and one of the side panels. 
Such a hinge connection would be subject to the same blushing problem as 
the hinge connection between the side panels. To prevent light damage to 
the container contents, ridges are formed on the side panel and the end 
cap to form a tortuous path for any light which leaks through the blushed 
area. 
Suspension plugs may be formed on the inner surfaces of the end caps, 
fitting within the inner core of a roll of light-sensitive material to 
keep the roll centered in the container. When such plugs are formed such 
as by thermoforming, the outer surfaces of the end caps have recesses 
therein such as shown in aforementioned U.S. Pat. No. 4,239,164. To some, 
the recess might be considered to be unattractive. We have provided flaps 
on the blank for folding over the outside of the end caps, to cover the 
recesses and provide a flush appearance to the container. 
The invention, and its objects and advantages will become more apparent in 
the detailed description of the preferred embodiments presented below.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a container according to the present invention 
includes a shell formed from a foldable blank 10. The blank includes hinge 
lines 12, 14, and 16 which define four rectangular panels 18, 20, 22, and 
24 connected together in series along mutually parallel edges of the 
panels. Blank 10 is foldable upon the hinge lines to form a rectangular 
tube. 
A pair of end caps 26 and 28 are hingedly connected to panel 20. End caps 
26 and 28 have formed-in roll suspension plugs 30 and 32. A pair of end 
cap covers 34 and 36 are hingedly connected to panel 24. 
Blank 10 may be made from a variety of suitable opaque material such as 
fiberboard and corrugated paperboard which possess desirable puncture, 
compression, and bursting strengths. However, in the preferred embodiment, 
the blank is made from thermoplastic material such as polystyrene to which 
a suitable pigment, carbon black for example, has been added for opacity. 
The blank preferably is formed by well-known thermoforming techniques from 
a sheet of such material. 
In accordance with the invention, means are provided in association with 
panels 18, 20, 22, and 24 for increasing the strength of the container and 
for forming a tortuous path to inhibit any light which may leak around the 
edges of the panels from reaching the interior of the container. In a 
preferred embodiment, such means includes a plurality of ramp-shaped 
ridges 38-44 formed in the panels. 
Ridges 40, 41, and 42 have, respectively, surfaces 54, 56, and 58 which are 
substantially normal to the panel and spaced along the inner surface of 
the panels by a predetermined distance from the associated hinge 
connection. In contrast, surfaces 60, 62, 64, and 66 on ridges 38, 39, 42, 
and 43, respectively, are closely adjacent to their associated hinge 
connection. Surfaces 60, 62, 64, and 66 extend normal to the panel by a 
height substantially equal to the distance that surfaces 54, 56, and 58 
are spaced from the hinge connections. 
FIG. 2 shows the manner of cooperation between the panel and ridge surfaces 
on either side of a hinge connection both to stiffen the corners and to 
inhibit any light which may leak through the thinned-out, or "blushed," 
hinge. As panel 18 is folded at hinge 12, surface 62 of ridge 39 folds 
into the space between surface 54 and the hinge. Should the material 
"blush" at the hinge connection, any light which leaked through the 
material in that region must travel along the space between panel 20 and 
surface 62, turn 90.degree., and travel between ridge 39 and surface 54 
before reaching the interior of the container. This tortuous path for the 
light assures ample protection and a lightlock for the contents of the 
container. Light protection is enhanced when surface 62 of the ridge is 
brought into intimate contact with the adjacent surface of panel 20. Also, 
the double thickness of material at the corners provides added stiffness 
to the package. 
FIG. 3 shows the completed container, all panels, end caps and end cap 
covers having been folded. The illustration includes a roll of 
light-sensitive material as it would be packaged in the container. While 
FIG. 2, described above, illustrates the structure at hinge line 12, it is 
to be understood that the same light protection and stiffening effects are 
provided at three corners of the rectangular tube formed by panels 18, 20, 
22, and 24; i.e., at hinge lines 12, 14, and 16. 
The fourth corner (shown sectioned in FIG. 4) forms an exit slot for 
light-sensitive material 70. A lip 72 is folded over from panel 18 and 
tucked into the container interior inside of panel 24. Lip 72 is urged 
toward panel 24 by its resiliency to inhibit light from entering the 
container. Plush material may be added to one or both sides of the exit 
slot to enhance the light protection. The exit slot may take various 
forms; a suitable example is shown in aforementioned U.S. Pat. No. 
4,239,164. Of course, it will be understood that the illustrated container 
is but one embodiment of the present invention, and that containers 
according to other embodiments may not have exit slots. 
After the panels have been folded to form a tube with four sides and two 
open ends as shown in FIG. 5, and a roll of strip material loaded into the 
tube, end caps 26 and 28 are folded inwardly to close the container. The 
hinge connection between the end caps and panel 20 are subject to blushing 
(and consequently to light-leaks) just as are hinge connections 12, 14, 
and 16. There is also the risk of light leak around the other three edges 
of each end cap 26 and 28. Structure associated with the end caps for 
inhibiting such light leaks will now be described. 
The end caps are formed with outwardly projecting flanges (76-79 on end cap 
28 and 80-83 on end cap 26, as shown in FIGS. 1, 5 and 6). When the end 
caps are folded in as shown in FIGS. 6 and 7, the flanges touch or lie 
closely adjacent to respective surfaces of panels 18, 20, 22 and 24. Any 
light which might travel inwardly between the end cap flanges and the side 
panels impinges upon the ends of ridges 38-44, and is prevented from 
reaching the interior of the container. 
Side panels 18 and 22 have small lips 90 formed on each end (FIG. 1). When 
blank 10 is folded up to form a carton, these lips extend over the 
associated flange 77, 79, 81, and 82 of end caps 26 and 28. Sealing the 
lips to the flanges completes the enclosure, and this may be done 
ultrasonically as shown in FIG. 8 using an ultrasonic horn and anvil 92 
and 94, respectively. 
Side panel 24 may also have a set of lips similar to lips 90, but for the 
preferred embodiment, we have provided end cap covers 34 and 36. Before 
sealing, the covers are folded over the exterior of the end caps to 
product a flush appearance to the container. 
The invention has been described in detail with particular reference to a 
preferred embodiment thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.