Abstract:
The disclosed invention provides a container made of paper and comprising an end wall opposite an opening, right and left side walls extending between the end wall and the opening, and upper and lower side walls extending between the end wall and the opening. Each of the side walls has at least a double layer construction consisting of a bend part and a foldback part bonded together. Cut edges of paper are disposed inwardly of the container away from the opening.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a container for receiving a video tape, floppy disks, or varied other articles, and more particularly to a paper container folded up to define an opening for putting such articles in and out. 
     A conventional foldup paper container of this type is illustrated in FIG. 8 of the accompanying drawings. As seen, a sheet of paper 01 includes bend parts 01a to 01i which constitute various parts of the container when folded up. The bend parts that will define an opening when folded up will have their edges exposed to outside. 
     This type of known paper container has the advantage of low cost over a container formed of plastics. However, since the edges of the bend parts defining the opening are always exposed to outside, these edges tend to be contacted by hands and articles resulting in generation of paper powder or particles as the edges wear. Because of this the illustrated paper container is not suitable for video tapes which are vulnerable to paper particles. Thus such a paper container has a limited range of use. 
     In order to solve or alleviate the problem, these edges may be coated with a resin such as polypropylene. However, it would necessitate an apparatus for applying the resin coating to be installed in the container production line, which would increase the equipment cost and container manufacturing cost. 
     SUMMARY OF THE INVENTION 
     This invention has been made in order to restrain the generation of paper powder or particles and provide a strong container by means of rational modification effected on part of a paper sheet. 
     The object of the invention, therefore, is to provide a paper container formed by folding up a sheet of paper comprising foldback parts continuous with at least those bend parts which will define an opening when the sheet is folded up to form the container. The foldback parts are adapted to be folded back inwardly of the container. 
     According to this invention, the foldback parts continuous with at least those bend parts which will define the opening are folded back inwardly of the container during the container forming process. Therefore the foldback parts do not have their respective edges exposed to the outside, whereby the edges are protected from contacts by hands and articles. Since the invention involves only partial modifications to the paper cutting process, the paper container is manufactured with a smaller number of manufacturing steps and a smaller number of machines than the case of coating the edges with a resin such as polypropylene. 
     Thus, the container according to this invention departs from the prior art container by the simple and inexpensive modification consisting in the foldback parts provided to be continuous with the bend parts of the paper sheet which will define the opening of the resulting container. Although the modification is simple and inexpensive, the container of this invention has the paper edges protected against wear due to sliding contacts by hands and articles thereby to minimize generation of paper powder or paper particles. Therefore, the paper container according to this invention is well suited for containing video tapes or floppy disks which are vulnerable to paper powder or particles. Moreover, the foldback parts advantageously act as reinforcements for the bend parts. This ensures a sufficient strength required of the container without substantially increasing the wall thickness of the container. Of course, the articles that can be placed in the container are not limited to video tapes and floppy disks, and the shape and size of the container may be chosen to suit the articles to be placed therein. 
     Other objects and advantages of this invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a developed perspective view of a foldup paper container according to a first embodiment of this invention, 
     FIGS. 2 and 3 are perspective views showing a foldup process, respectively, 
     FIG. 4 is a perspective view of the container as folded up, 
     FIG. 5 is a sectional view taken on line V--V of FIG. 4, 
     FIG. 6 is a developed perspective view of a second embodiment, 
     FIG. 7 is a developed plan view of a third embodiment, 
     FIG. 8 is a developed perspective view of a foldup paper container according to the prior art, 
     FIG. 9 is a developed plan view of the first embodiment, 
     FIG. 10 is a developed plan view of a fourth embodiment, 
     FIG. 11 is a developed plan view of a fifth embodiment, and 
     FIG. 12 is a developed plan view of a sixth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Several embodiments of this invention will be described hereinafter with reference to the accompanying drawings. 
     Referring to FIGS. 1 through 5 and FIG. 9, a sheet of paper 1 is shown which is folded up to form a box or container for a video tape which is one example of articles to be placed in the container. The container defines an opening S for putting the video tape in and out. The sheet of paper 1 comprises a rectangular bend part 1a which constitutes a back end wall of the container, and a pair of rectangular outer bend parts 1b and 1c continuous with opposite long sides of the bend part 1a and constituting righthand and lefthand side walls of the container. As used throughout this disclosure, the term &#34;bend part&#34; refers to a substantially planar panel which is attached to at least one other substantially planar panel along a bend or fold. A &#34;foldback part&#34; is a bend part which is dimensioned substantially to overlie another bend part resulting in a double layer construction. 
     The first and second outer bend parts 1b and 1c constituting the side walls have first and second upper bend parts 1d and 1f, as well as third and fourth lower bend parts 1e and 1g continuous with short sides of the outer bend parts. 
     These four upper and lower bend parts 1d to 1g constitute layers of upper and lower walls of the container. The bend part 1a constituting the back end wall has triangular foldback parts 1h and 1i continuous with short sides thereof. The triangular foldback parts 1h and 1i are adapted to overlap the two upper bend parts 1d and 1f and the two lower bend parts 1e and 1g, respectively. 
     The sheet 1 further comprises first and second inner foldback parts 2a and 2b extending from those sides of the outer bend parts which define the opening S of the container. The inner foldback parts 2a and 2b are folded into the container so that cut edges thereof are located in contact with or adjacent inside faces of the bend part 1a constituting the end wall and of the upper and lower bend parts 1d to 1g constituting the upper and lower walls. A cutout 3 which is a combination of a triangular cutout and a semicircular cutout is defined at a vertically intermediate position between each of the outer bend parts 1b and 1c and each of the inner foldback parts 2a and 2b. These cutouts 3 facilitate putting the video tape in and out. The outer bend parts 1b and 1c include foldback tabs 2c and 2d continuous therewith at edges of the triangular cutouts, respectively. These foldback tabs 2c and 2d are folded to contact or lie adjacent to edges of the semicircular cutouts defined in the inner foldback parts 2a and 2b. 
     As shown in FIG. 9, the first inner foldback part 2a has a width W substantially equal to a width V of the first outer bend part 1b, and the second inner foldback part 2b has a width X substantially equal to a width Y of the second outer bend part 1c. 
     The width W is equal to the width Y. 
     The upper bend parts 1d and 1f constituting the upper wall have first and second upper foldback parts 2e and 2g continuous with long sides thereof, respectively. The lower bend parts 1e and 1g have third and fourth lower foldback parts 2f and 2h continuous with long sides thereof respectively. The upper and lower foldback parts 2e to 2h are folded so that edges thereof are placed in contact with or adjacent the outer bend parts 1b and 1c constituting the side walls of the container. The upper and lower bend parts 1d to 1g constituting the upper and lower walls of the container further include triangular foldback parts 2i to 2n and triangular cutouts 2o and 2p at short sides thereof. These foldback parts 2i to 2n and cutouts 2o and 2p have edges overlapping the triangular foldback parts 1h and 1i or placed in contact with or adjacent to edges of the triangular foldback parts 1h and 1i. 
     When the sheet 1 is folded up to form the container, the foldback parts 2a to 2n continuous with the sides of the bend parts 1a to 1g are folded inwardly on the container as shown in FIG. 2. Therefore, the cut edges of the foldback parts are protected from sliding contacts by hands and articles. Compared for example with the case of cut edges of the sheet being exposed to outside, the construction of this invention restrains generation of paper powder or particles due to frictions caused by such sliding contacts. The described embodiment further diminishes the generation of paper powder or articles from those edges of the foldback parts 2a to 2n by placing the edges in contact with or adjacent to the other components when the sheet 1 is folded up. 
     Where the sheet of paper 1 has inner bend walls coated with a thermoplastic resin such as polyethylene or polypropylene in a thickness of 25-30 microns, the bend parts and foldback parts may be thermally fused together by using an existing polyethylene or polypropylene container manufacturing plant without any modification to the plant and without using an adhesive. The constituent parts may of course be bonded together by means of an adhesive. 
     It will be noted that reference a in the drawings denotes fold lines along which the bend parts and foldback parts may be folded in an accurate and reliable manner. 
     The other embodiments will be described hereinafter. 
     Referring to FIG. 6 showing a second embodiment, the sheet of paper 1 further comprises a reinforcing inner foldback part 2q continuous with one of the inner foldback parts 2a and 2b. This reinforcing foldback part 2q, when the sheet 1 is folded up to form a container, overlaps an inside face of the bend part 1a constituting the end wall of the container. 
     Referring to FIG. 7 showing a third embodiment, the sheet of paper 1 includes foldback parts 2a and 2b each in a shape of half ellipse smaller in area than the bend part 1b or 1c constituting an outer side wall of the container. The upper and lower bend parts 1d to 1g constituting the upper and lower walls of the container have semicircular tabs or foldback parts 2i to 2p continuous with short sides thereof. The upper and lower foldback parts 2e to 2h define corresponding semicircular cutouts 2q to 2x at short sides thereof for mating with the semicircular foldback parts 2i to 2p. 
     Furthermore, in the third embodiment the cutouts 3 for facilitating putting in and out of the video tape each include a convex trapezoidal cutout having three semicircular tabs or foldback parts 2c or 2d which are placed in contact with or adjacent to edges of three semicircular concavities defined in the foldback part 2a or 2b. 
     Referring to FIG. 10 showing a fourth embodiment, the sheet includes no parts corresponding to the foldback parts 2e and 2f and the triangular foldback parts 2k and 2m in the first embodiment shown in FIG. 9. Triangular foldback parts 2i&#39; and 2j&#39; in this embodiment are longer than the corresponding parts 2i and 2j of FIG. 9 and substantially equal an entire width of the main foldback part 2a. Thus, the upper and lower bend parts 1d to 1g are reinforced with added rigidity by the upper and lower foldback parts 2i&#39; and 2j&#39; when the sheet is folded up to form a container. However, no cutouts are defined in the sheet. 
     Referring to FIG. 11, a fifth embodiment shown therein differs from the embodiment of FIG. 10 in that a hexagonal cutout 3&#39; is defined between the first outer bend part 1b and the first inner foldback part 2a and a similar cutout 3&#39; is defined between the second outer bend part 1c and the second inner foldback part 2b. Thus, the fifth embodiment has an advantage over the fourth embodiment in that an article such as a video tape may be put in and out with ease. 
     FIG. 12 shows a sixth embodiment which comprises a paper container suited for floppy disks. This embodiment is different from the embodiment of FIG. 9 in the following respects: 
     (i) Foldback parts 2i&#34; and 2j&#34; are larger than the foldback parts 2i and 2j. 
     (ii) The foldback parts 2e and 2f are not provided. 
     (iii) Bend parts 1h&#34; and 1i&#34; are larger than the bend parts 1h and 1i. 
     (iv) The foldback parts 2g&#39; and 2h&#39; are triangular. 
     (v) The parts 1h&#34; and 2k are not continuous. 
     (vi) The cutouts 3 are not provided. 
     (vii) The bend parts 1d&#39; and 1e&#39; include no cutouts. 
     The sixth embodiment, however, is the same in principle as the first embodiment shown in FIG. 9.