Background Art [2] In general, a'foldable container'refers to a transport container or box having front and rear plates and left and right plates hinge-coupled to the peripheral edge of a base plate so that the container can be folded and unfolded. When the container is transported, handled, or stored while containing articles, it is unfolded and used in a normal container shape. When it contains no article, it is simply folded to reduce the volume. As such, the storage and transport spaces are reduced and the distribution and storage costs decrease.

[3] The foldable container as mentioned above is generally molded into a hexahedron shape by plastic injection so that it can be stacked without occupying unnecessary space during transport and storage.

[4] Typical examples of conventional foldable containers are disclosed in Korean Patent Publication No. 2002-0062714 (publication date: July 29,2002) in the name of Hwasan Junggong Company and Korean Registered Utility Model No. 20-0169031 (registration date: November 16,1999) in the name of National Plastic Company.

[5] Above-mentioned Korean Patent Publication No. 2002-0062714 proposes a con- ventional foldable container having lockers 60'of a special type as shown in FIGs. 1 and 2. The container includes a base plate 10' ; front and rear plates 30'hinge-coupled to the front and rear edges of the base plate 10'via hinge portions 12' ; left and right plates 20'hinge-coupled to the left and right edges of the base plate 10'via hinge portions 11' ; first coupling portions 40'formed on both lateral ends of the left and right plates 20'and having a number of coupling protrusions, fixing protrusions, and locking holes; second coupling portions 50'formed on the front and rear plates 30'and having a number of coupling grooves so that the first coupling portions 40'can be fitted and coupled thereto; and lockers 60'having a slide plate, a locking protrusion, an elastic support member, and a handle to maintain the left and right plates 20'and the front and rear plates 30'in an upright position.

[6] Above-mentioned Korean Registered Utility Model No. 20-0169031 proposes a conventional foldable container having lockers 60'of a special type as shown in FIG.

3. The container includes a base plate 10' ; front and rear plates 30'hinge-coupled to the lower protrusion ends 11'of the base plate 10'via hinge portions 11'a and 31' ; left and right plates 20'hinge-coupled to the higher protrusion ends 12'of the base plate 10'via hinge portions 12a'and 21' ; fastening plates 22'extending from both sides of the left and right plates 20'and having a fastening groove; corresponding fastening protrusions 32'formed on the front and rear plates 30' ; and a pair of card support pins 70' positioned on the left and right plates 20'.

Disclosure of Invention Technical Problem [7] Conventional foldable containers as mentioned above, however, have a problem as follows: their base plate, front and rear plates, and left and right plates are either completely sealed or made up of plate members having some holes perforated therein.

As a result, they are substantially heavier than the foldable container having a plastic film sheet window according to the present invention. In addition, they have an increased number of parts having special and complex shapes and need a large amount of plastic. This inevitably increases the cost for plastic resin raw material, cost for fabricating molds, and assembly cost.

Technical Solution [8] Therefore, the present invention has been made in view of the above-mentioned problems, and it is the first object of the present invention to provide a foldable lightweight container capable of improving the distribution workability.

[9] It is the second object of the present invention to provide a foldable lightweight container having enough support strength to be stacked, in spite of reduced weight.

[10] It is the third object of the present invention to provide a foldable lightweight container which needs a substantially reduced amount of plastic resin during manu- facturing and which does not adopt a complex locker configuration for reduced number of parts so that the container can be assembled with ease and convenience and can be manufactured with reduced raw material cost, mold cost, and assembly cost.

[11] It is the fourth object of the present invention to provide a foldable lightweight container making it possible to easily attach, remove, and replace a name plate which indicates information on articles contained therein, transport information, or storage in- formation or which displays a visual advertisement.

[12] It is the fifth object of the present invention to provide a foldable lightweight container making it possible to check the articles contained therein with ease and correctness from every direction, even when the container is stacked, for improved dis- tribution workability.

[13] According to a preferred aspect of the present invention, in order to accomplish the first, third, and fifth objects of the present invention, there is provided a foldable lightweight container having a plastic film sheet window formed on a surface of at least one of the base plate, the front and rear plates, and the left and right plates thereof.

[14] According to another preferred aspect of the present invention, in order to accomplish the second object of the present invention, there is provided a foldable lightweight container having a support bar fitted at least into both corners of the front and rear plates or the left and right plates thereof.

[15] According to another preferred aspect of the present invention, in order to accomplish the fourth object of the present invention, there is provided a foldable lightweight container having a card or name plate insertion portion so that a card or name plate which indicates information on the kind, amount, or destination of articles or which displays advertisement copy or image can be inserted, removed, and exchanged.

[16] According to another preferred aspect of the present invention, in order to accomplish the above-mentioned objects of the present invention, there is provided a foldable lightweight container having a film sheet window including a base plate having first and second protrusion frames, left and right plates hinge-coupled to the first protrusion frame and having a plastic film sheet window formed on most central region thereof; and front and rear plates hinge-coupled to the first protrusion frame and having a plastic film sheet window formed on most central region thereof, wherein, when the container is unfolded, the upper traverse frame of the left and right plates are fastened and fixed to the upper traverse frame of the front and rear plates and, when the container is folded, the front and rear plates are folded toward the interior of the base plate by pivot motion and then the left and right plates are folded on the upper surfaces of the folded front and rear plates by pivot motion.

Description of Drawings [17] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: [18] FIG. 1 is a perspective view showing the overall construction of a conventional foldable container; [19] FIG. 2 is an exploded perspective view showing the structure of left and right plates of the foldable container shown in FIG. la; [20] FIG. 3 is an exploded perspective view showing the overall construction of another conventional foldable container; [21] FIG. 4 is a perspective view showing a foldable lightweight container having a film sheet window according to a preferred embodiment of the present invention; [22] FIG. 5 is a perspective view showing the foldable lightweight container having a film sheet window shown in FIG. 3, which is partially folded; [23] FIG. 6 is a perspective view showing the foldable lightweight container having a film sheet window shown in FIG. 3, which is completely folded; [24] FIG. 7 is a perspective view magnifying a fastening portion of left and right plates; [25] FIG. 8 is a perspective view showing a fastener to be mounted on the fastening portion shown in FIG. 6; and [26] FIG. 9 is a perspective view illustrating the mounting of the fastener shown in FIG.

7 on a structure similar to the fastening portion shown in FIG. 6.

Best Mode [27] Reference will now be made in detail to the preferred embodiments of the present invention.

[28] FIG. 4 is a perspective view showing a foldable lightweight container 1 having a plastic film sheet window according to a preferred embodiment of the present invention, FIG. 5 is a perspective view showing the foldable lightweight container 1 which is partially folded, and FIG. 6 is a perspective view showing the foldable lightweight container which is completely folded.

[29] The foldable lightweight container 1 having a plastic film sheet window according to the present invention as shown in the drawings includes a base plate 10 having first and second protrusion frames 13 and 14; left and right plates 30 hinge-coupled to both ends of the first protrusion frame 13 and having a film sheet window 30 formed on most central region thereof; and front and rear plates 20 hinge-coupled to the second protrusion frame 14 and having a film sheet window 21 formed on most central region thereof.

[30] Support bars 80 may be selectively placed upright on the corner (given no reference numeral) of both ends of the left and right plates 30 as shown in the drawings, in order to provide enough support strength to stack a number of foldable lightweight containers 1 according to the present invention. Although not shown in the drawings, the support bars 80 may also be placed upright on the corner (given no reference numeral) of both ends of the front and rear plates 20 if necessary. In addition, the supports bars 80 may be placed on four corners of the base plate 10 if necessary and may be placed in any position along the horizontal direction to enhance the traverse strength of the front and rear plates 20 and/or the left and right plates 30.

[31] The support bars 80 may be made up of any material capable of providing enough support strength, including aluminum, steel, stainless steel, any alloy thereof, en- gineering plastic, and reinforced ceramic.

[32] The support bars 80 may be integrally formed when molding the left and right plates 30 by insert molding. Alternatively, bar insertion through-holes may be previously formed when molding the left and right plates 30 and the support bars 80 may be inserted into the left and right plates 30 which have been molded. In addition, caps (not shown) having an enlarged area may be mounted on both ends of the inserted support bars 80 by suitable means including screw fixing and press fit fixing.

[33] The base plate 10 in the embodiment as shown includes first and second protrusion frames 13 and 14, a grating structure 12 integrally formed between them to define a number of square or rectangular gratings for reduced weight, and a large bottom film sheet window 11 to seal between the gratings. The bottom film sheet window 11 may be positioned on the upper surface, lower surface, or middle of thickness of the grating structure 12. The bottom film sheet window 11 may also be attached to the upper surface of the grating structure 12, in order to avoid wear caused by friction with the bottom surface on which a box is placed, or integrally formed on the upper surface or the middle of thickness thereof by insert molding. The configuration of the grating structure 12 is not limited in the present invention and may be chosen by those skilled in the art. For example, the base plate 10 may be a square or rectangular plate having no bottom film sheet window 11 or grating structure 12.

[34] Although the left and right plates 30 in the embodiment as shown have a large film sheet window 31 formed on most central region of the interior thereof, the film sheet window may be formed on the exterior or middle portion as mentioned above. If necessary, a plurality of vertical supports 33 may be formed between the upper and lower traverse frames 36 and 36a of the left and right plates 30 or of the front and rear plates to enhance support strength.

[35] The magnified section of FIG. 4 shows a rivet portion 33b for fixing the film sheet window 31 to the interior of the vertical supports 33. The configuration of the rivet portion 33b is not limited in the present invention and can be chosen by those skilled in the art.

[36] The rivet portion 33b may be formed as follows: at least one through-hole 31a is previously formed in any suitable place on the film sheet window 31 which abuts the interior of the vertical supports 33. The vertical supports 33 are then formed in a mold by insert molding in such a manner that the molding resin passes through and fills the through-hole 31 and forms a penetrating portion 33d, which is integral with the rivet portion 33b. In this manner, the film sheet window 31 is more firmly fixed to the left and right plates 30.

[37] The same structure may be formed on the front and rear plates 20 and/or the base plate 10, in addition to the left and right plates 30.

[38] The upper traverse frame 36 may be of a solid or hollow structure having a planar surface and a sectional shape of a square, a rectangle, a circle, or an ellipse. In the embodiment as shown, a number of vertical supports 35 are formed between the horizontal supports 34 and 34b on the strip for reduced weight and enhanced strength.

[39] In the embodiment as shown in the drawings, a plurality of vertical supports 35a are positioned on both ends of the left and right plates 30 for enhanced support strength and a plurality of traverse supports 34a are formed between the vertical supports 35a.

Both ends of the left and right plates 30 are bent toward the front and left plates and extend slightly to form extensions 37, which have the same structure as that of the above-mentioned both ends. The extensions 37 have a concave engagement portion 38 formed on the upper inner portion of the extension surface thereof in a position extending inward from an opening 38b. The entrance of the concave engagement portion 38 is delimited by a single or a pair of stepped portion (s) 38a. The existence of the extension 37 is, however, not limited in the present invention and can be chosen by those skilled in the art. If the extension 37 is omitted, the opening, stepped portion, and concave engagement portion are formed on the upper inner portion of both ends of the left and right plates 30.

[40] If necessary, a grip portion 32 may be preferably formed on the upper central portion of the left and right plates 30 for improved user convenience.

[41] Although the front and rear plates 20 in the embodiment as shown have a large film sheet window 21 formed on most central region of the interior thereof, the film sheet window may be formed on the exterior or middle portion as mentioned above. If necessary, a plurality of vertical supports 23 may be formed between the upper and lower traverse frames 24 and 29 of the front and rear plates 20 for enhanced support strength.

[42] The shape and structure of the upper traverse frame 24 are substantially equal to those of the above-mentioned upper traverse frame 36 of the left and right plates 30 and a number of vertical supports 25 are formed between the horizontal supports 28 and 28a on the strip for reduced weight and enhanced strength. The vertical supports 25 may be vertically positioned or slanted.

[43] The front and rear plates 20 in the embodiment as shown have a plurality of lon- gitudinal frames 26 formed on both ends thereof for enhanced support strength. If necessary, additional horizontal supports (not shown) may be formed between the lon- gitudinal frames 26.

[44] A grip portion 22 may be preferably formed on the upper central portion of the left and right plates 20 for improved user convenience.

[45] In the embodiment as shown in the drawings, at least one card support table 24a may be integrally molded with the front and rear plates 30 during molding in such a manner that it traverses between at least two vertical supports 23 in the horizontal direction. Alternatively, a concave hole may be formed on the exterior of at least two vertical supports 23 and the card support table 24a may be press-fitted into the concave hole in such a manner that it can be fastened and removed. The card support table 24a has a width smaller than that of the vertical supports 23 so that a card or name plate which indicates information on the kind, amount, or destination of articles or which displays advertisement copy or image can be inserted, removed, and exchanged.

[46] Consequently, at least two vertical supports 23 and at least one card support table 24a constitute a card insertion portion (given no reference numeral) and such a feature may be positioned on one or both of the front and rear plates 20 or on least one of the left and right plates 30 within the scope of the present invention.

[47] A hinge portion 40 includes a pair of fixing connectors 42 and 43 formed on both inner ends of the first protrusion frame 13 and having a fastening hole (not shown) formed at the center thereof and connection protrusions 41 extending downward from both lower ends of the left and right plates 30 and having a protrusion pin (not shown) inserted into both fastening holes in such a manner that it can pivot.

[48] Such a configuration of the hinge portion 40 enables the left and right plates 30 positioned on the first protrusion frame 13 to be folded toward the interior of the base plate 10.

[49] A front and rear plate hinge portion 70 includes protrusion pin formation portions 27 formed on both lower ends of the longitudinal frames 26 of the front and rear plates 20 and a long groove 71 formed on the protruding extension surface of the outer fixing connector 42 of the base plate 10. The front and rear plates 20 are slightly slanted during assembly so that the protrusion pin (not shown) of the protrusion pin formation portion 27 is inserted into the long groove 71. Consequently, the front and rear plates 20 can be folded toward the interior of the base plate 10 by pivot motion.

[50] The front and rear plates 20 are fastened and fixed to the left and right plates 30 by moving circular protrusions 26a formed on both upper sides of the front and rear plates 20 into the concave engagement portions 38 via the openings 38b formed on the interior of both extensions 37 of the left and right plates 30 and fastening and fixing them by the stepped portions 38a.

[51] The procedure for folding the foldable lightweight container 1 having a film sheet window according to the present invention will now be described with reference to FIGs. 4 to 6. The front and rear plates 20 and the left and right plates 30 are initially fastened and fixed to each other wile being positioned upright as shown in FIG. 5. The upper ends of the front and rear plates 20 are then pushed toward the interior of the base plate 10 as shown in FIG. 5 so that the circular protrusions 26a formed on both upper ends of the front and rear plates 20 are released from the concave engage portions 38 formed on the upper ends of the extensions 27 of the left and right plates 30 and moved out of the stepped portions 38a via the openings 38b. Consequently, the front and rear plates 20 are folded on the inner surface of the base plate 10 by pivot motion caused by the front and rear plate hinge portion 70. The left and right plates 30 are then folded on the outer surface of the front and rear plates 20 by pivot motion caused by the lateral plate hinge portion 40 as shown in FIG. 6.

[52] The procedure for unfolding the container 1 into a box shape from the folded state shown in FIG. 6 is the opposite of the above-mentioned procedure and detailed de- scription thereof will be omitted.

[53] The bottom film sheet window 11, the film sheet windows 21 of the front and rear plates 20, and the film sheet windows 31 of the left and right plates 30 may be transparent, semi-transparent, or opaque and the choice can be based on the kind or characteristics of contained articles, the intention of the person in charge of storage or display, or the taste of consumers. The windows may be given a color when they are semi-transparent or opaque and the color may be chosen in the same manner as mentioned above.

[54] The material and thickness of the windows are not limited in the present invention.

The material can be generally chosen from various resin materials including polyethylene terephthalate, polyethylene, polypropylene, polystyrene, acetal, nylon, fluoride resin, acryl, and polycarbonate, in consideration of the characteristics of articles to contain or the place or purpose of using or storing the container. The thickness is generally in the range of 0. 3-1. 5mm, and preferably in the range of 0.3-0. 8mm.

[55] The sheet can be integrally molded and fabricated by an insert molding process.

Alternatively, at least one opening may be formed on a portion on which the sheet is to be formed and, after molding, the sheet may be inserted or glued to the groove which has been previously formed for easy fastening or exchange.

[56] FIG. 7 shows an alternative embodiment to the embodiment shown in FIGs. 4 to 6 and magnifies the fastening portion 60 of the front and left plates 30.

[57] Although the left and right plates 30 has no extension (as labeled 27 in FIG. 5) in the alternative embodiment as shown, the fastening portion 60 may be applied to the embodiment shown in FIGs. 4 to 6.

[58] The fastening portion 60 of the left and right plates 30 includes a fastening stopper 61 having a latching step 62 formed on the lower portion thereof, a stepped portion 63 formed below the fastening stopper 61, and a concave portion 65 formed above the fastening stopper 61. A protrusion end 64 is formed as low as the thickness of the extension (not shown) of the front and rear plates 20.

[59] FIG. 8 is a perspective view showing a fastener 50 to be mounted on the fastening portion 60 shown in FIG. 7. The fastener 50 is a plate having a general shape of a rectangle and includes an opening 53 fastened to the fastening stopper 61 shown in FIG. 7, a protruding head 51 acting as a knob protruding upward through a shoulder 52, and a protrusion 54 formed by two concave grooves 55 and equipped with an elastic member such as a spring 54.

[60] FIG. 9 is a perspective view illustrating the mounting of the fastener 50 shown in FIG. 8 on a structure similar to the fastening portion 60 shown in FIG. 7 (i. e. , a structure having an extension 27 as shown in FIGs. 4 to 6). The opening 53 of the fastener 50 is fastened to the latching step 62 of the fastening stopper 61. The protruding head 51 of the fastener 50 is maintained in an upright position by the elastic force from the spring 56 and protrudes through a fastening hole 20b formed on extensions 20a, which extend from both upper ends of the front and rear plates 20, to be fixed. As such, the front and rear plates 20 are fastened and fixed to the left and right plates 30 in an upright position.

[61] Release from the fastened and fixed state can be performed by pushing the protruding head 51 of the fastener 50 downward. The front and rear plates 20 are then separated from the left and right plates 30. After the release, the protruding head 51 returns to the original state by removing the pushing force.

[62] Reference numeral 57 in the drawing refers to a cover plate for hiding the fastener 50 and reference numeral 80 refers to a support bar.

Industrial Applicability [63] [64] As can be seen from the foregoing, the foldable lightweight container having a film sheet window according to the present invention has advantages as follows: it has reduced weight due to the opening formed in the region to which the sheet is fastened; it needs a substantially reduced amount of plastic resin during manufacturing because of the existence of the opening; it does not adopt a complex locker configuration for reduced number of parts and ease assembly so that it can be manufactured with reduced raw material cost, mold cost, and assembly cost; it uses a transparent film sheet so that contained articles can be checked with ease and correctness from every direction even when it is stacked; its window has various colors to give workers aesthetic and agreeable feeling for improved distribution workability; optionally, it can easily attach, remove, and replace a name plate which indicates information on articles contained therein, transport information, or storage information or which displays a visual advertisement; and it may have a steel bar having enough support strength for stacking in spite of reduced weight.

[65] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings, but, on the contrary, it is intended to cover various modifications and variations within the spirit and scope of the appended claims.