# Patent

## Title
Folding container

## Abstract

A lock member L1 including an operation portion L1a and a lock bar L1b is disposed on each of first opposite side walls 2 to be brought down firstly toward a bottom portion 1, and a pivotal shaft 13 formed in the operation portion is pivotally supported in a bearing hole 2g2 formed in each of the first opposite side walls to be brought down firstly toward the bottom portion. To allow cancellation of a lock state between the lock member and each of second opposite side walls to be brought down secondly toward the bottom portion, the operation portion is pivotally moved downward. During an unlocking operation, even when an operator pivotally moves the operation portion included in the lock member, the operation portion is prevented from being tilted. Thus, the lock bar of the lock member can be used to reliably perform the unlocking operation.

## Background
FIELD OF THE INVENTION
The present invention relates to a folding container in which side walls disposed so as to surround a bottom portion can be folded so as to lie on top of the bottom portion.
BACKGROUND OF THE INVENTION
Folding containers are conventionally known which are composed of long side walls connected, via hinge members, to respective opposite long side portions of a bottom portion formed so as to have a rectangular planar shape and short side walls also connected, via hinge members, to respective opposite short side portions of the bottom portion. The long side walls and the short side walls are set up perpendicularly to the bottom portion to assemble the side walls and the bottom portion into a box form. Furthermore, when the folding container is folded, the long side walls and the short side walls are folded so as to lie on top of the bottom portion. With the folding container assembled into the box form, the long side walls and the short side walls are locked by lock members so as to prevent the long side walls or the short side walls from falling down toward the bottom portion.
By way of example, the Unexamined Japanese Patent Application Publication (Tokkai) No. 2003-40263 discloses a folding container in which a locking operation and an unlocking operation are performed as follows. An operation portion of a lock member disposed on each short side wall is moved in a vertical direction. Furthermore, the vertical movement of the operation portion is converted into horizontal movement via an appropriate mechanism such as a link mechanism to move a bar-like member to move in a horizontal direction. The tip of the bar-like member is thus inserted into or removed from an engaging portion formed in a corresponding long side wall. Consequently, the long side walls and the short side walls are locked or unlocked so as to prevent the short side walls from falling down toward a bottom portion.
According to the above-described conventional folding container, to fold the folding container assembled into the box form, an operator pushes the operation portion downward. However, depending on a position where the operator pushes the operation portion downward, the operation portion may be tilted during the downward movement instead of being moved downward in a horizontal state. Where the operation portion is tilted during the downward movement, the paired bar-like members positioned on the right and left of the operation portion vary in projection amount or retraction amount. This disadvantageously results in an unreliable unlocking operation.
Furthermore, the vertical movement of the operation portion is converted into the horizontal movement of the bar-like members via a complicated mechanism. Thus, a heavy transmission loss is involved in the conversion of the vertical movement of the operation portion into the horizontal movement of the bar-like members. Thus, a strong force is required to move the operation portion in the vertical direction, hindering a quick unlocking operation.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems with the above-described conventional folding container.
To accomplish the above-described object, the present invention provides a folding container having first opposite side walls which, when the folding container is in an assembled box form, are brought down firstly toward a bottom portion, and second opposite side walls which are brought down secondly toward the bottom portion after the first opposite side walls haven been brought down, wherein a lock member comprising an operation portion and a lock bar is disposed on each of the first opposite side walls to be brought down firstly toward the bottom portion, and a pivotal shaft formed in the operation portion is pivotally supported in a bearing hole formed in each of the first opposite side walls to be brought down firstly toward the bottom portion, and wherein to allow cancellation of a lock state between the lock member and each of the second opposite side walls to be brought down secondly toward the bottom portion, the operation portion is, when the lock member is in the locked state, pivotally moved upward or downward.
In the folding container having the first opposite side walls which, when the folding container is in the assembled box form, are brought down firstly toward the bottom portion and the second opposite side walls which are brought down secondly toward the bottom portion after the first opposite side walls haven been brought down, the lock member comprising the operation portion and the lock bar is disposed on each of the first opposite side walls to be brought down firstly toward the bottom portion, and the pivotal shaft formed in the operation portion is pivotally supported in the bearing hole formed in each of the first opposite side walls to be brought down firstly toward the bottom portion. Furthermore, to allow the lock member to be unlocked from each of the second opposite side walls to be brought down secondly toward the bottom portion, the operation portion is, when the lock member is in the locked state, pivotally moved upward or downward. Thus, during the unlocking operation, the operation portion is prevented from being tilted even when the operator pivotally moves the operation portion belonging to the lock member. Consequently, the unlocking operation can be reliably achieved using the lock bar belonging to the lock member.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a folding container according to the present invention assembled in a box form.
FIG. 2 is partial perspective view of a short side wall included in a folding container according to the present invention.
FIG. 3 is partial perspective view of a long side wall included in the folding container according to the present invention.
FIG. 4 is a partly enlarged perspective view of the long side wall included in the folding container according to the present invention.
FIG. 5 is an exploded perspective view of a lock member included in the folding container according to the present invention.
FIG. 6 is a perspective view of an operation portion of the lock member included in the folding container according to the present invention.
FIG. 7 is, like FIG. 6, a perspective view of the operation portion of the lock member included in the folding container according to the present invention.
FIG. 8 is a perspective view of a lock bar of the lock member included in the folding container according to the present invention.
FIG. 9 is, like FIG. 8, a perspective view of the lock bar of the lock member included in the folding container according to the present invention.
FIG. 10 is an exploded perspective view of the long side wall and the lock member included in the folding container according to the present invention.
FIG. 11 is an exploded perspective view of the long side wall and the lock member included in the folding container according to the present invention.
FIG. 12 is a partly enlarged perspective view including a partly sectional view and showing that the lock member is assembled to the long side wall of the folding container according to the present invention.
FIG. 13 is a partly enlarged perspective view showing that the lock member is assembled to the long side wall of the folding container according to the present invention.
FIG. 14 is a partly enlarged perspective view showing that the short side wall is locked to the lock member assembled to the long side wall of the folding container according to the present invention.
FIG. 15 is a partial perspective view showing that the lock member is assembled to the long side wall of the folding container according to the present invention.
FIG. 16 is a partly enlarged perspective view including a partly sectional view and showing that the lock member is assembled to the long side wall of the folding container according to the present invention.
FIG. 17 is a partly enlarged perspective view illustrating that the short side wall is unlocked from the lock member assembled to the long side wall of the folding container according to the present invention.
FIG. 18 is an exploded perspective view of a long side wall and a lock member included in a folding container according to another embodiment of the present invention.
FIG. 19 is a perspective view of an operation portion included in the lock member according to the embodiment shown in FIG. 18.
FIG. 20 is a partly enlarged sectional view perpendicular to a plate-like portion of the long side wall with the lock member assembled thereto in the embodiment shown in FIG. 18.
FIG. 21 is, like FIG. 20, a partly enlarged sectional view perpendicular to the plate-like portion of the long side wall with the lock member assembled thereto in the embodiment shown in FIG. 18.
FIG. 22 is a perspective view of an operation portion of a lock member included in a folding container according to yet another embodiment of the present invention.
FIG. 23 is a partly enlarged perspective view illustrating that a short side wall is locked to the lock member assembled to a long side wall according to the yet another embodiment shown in FIG. 22.
FIG. 24 is, like FIG. 23, a partly enlarged perspective view illustrating that the short side wall is unlocked from the lock member assembled to a long side wall according to the yet another embodiment shown in FIG. 22.
FIG. 25 is a partial perspective view of a long side wall included in a folding container according to still another embodiment of the present invention.
FIG. 26 is an exploded perspective view of a lock member assembled into the folding container shown in FIG. 25.
FIG. 27 is a partly enlarged perspective view of a lock bar included in the lock member assembled into the folding container shown in FIG. 25.
FIG. 28 is a partly enlarged perspective view of the lock member assembled into the folding container shown in FIG. 25.
FIG. 29 is a partly perspective view of a long side wall of the folding container shown in FIG. 25.
FIG. 30 is a partial perspective view of a long side wall to which a variation of the lock member shown in FIG. 25 is assembled.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will be described below. However, the present invention is not limited to the embodiment, and any other embodiment is possible without departing from the spirit of the present invention.
As shown in FIG. 1, a folding container according to the present invention is composed of a bottom portion 1, long side walls 2A hinged to respective long-side bank portions la of the bottom portion 1, and short side walls 3A hinged to respective short-side bank portions 1b of the bottom portion 1. In the present embodiment, each of the long-side bank portions 1a is formed to be lower than each of the short-side bank portions 1b. 
When the folding container is in an assembled box form as shown in FIG. 1, firstly, the long side walls 2A are brought down so as to lie on top of the bottom portion 1. Then, the short side walls 3A are brought down so as to lie on top of the long side walls 2A laid on top of the bottom portion 1. Thus, as is well known, the folding container can be folded into a low, compact form. Then, when the folding container is in a folded form, the short side walls 3A are set up vertically, and the long side walls 2A are set up vertically. Then, as shown in FIG. 1, the folding container can be assembled into the box form.
Now, the short side wall 3A will be described with reference to FIGS. 1 and 2.
The short side wall 3A has a plate-like portion 3a. An upper-end horizontal rib 3b is formed at the upper end of the short side wall 3A. Furthermore, a vertically long short side wall-side engaging member 3c is formed at each of opposite vertical ends of the short-side wall; the short side wall-side engaging member 3c is perpendicular to the plate-like portion 3a and to an inner surface (the surface which, when the folding container is assembled into the box form, is positioned inside the folding container assembled into the box form) 3a1 of the plate-like portion 3a. A vertically long prismatic block (hereinafter simply referred to as a corner block) 3d is formed in a corner portion formed by the inner surface 3a1 of the plate-like portion 3a and a vertically long band-like plate (hereinafter referred to as an end-side vertical plate) 3c1 included in the short wall-side engaging member 3c and which is perpendicular to the inner surface 3a1 of the plate-like portion 3a. Moreover, a pair of opposite, horizontal projecting pieces 3d2 and a vertical projecting piece 3d3 are formed at the upper end of a surface 3d1 of a corner portion vertically-long block 3d which lies parallel to the plate-like portion 3a; the vertical projecting piece 3d3 couples together the ends of the horizontal projecting piece 3d2 which lie opposite the end-side vertical plate 3c1. An engaging recess portion 3e is formed at the upper end of the corner block 3d which is surrounded by the horizontal protruding pieces 3d2, the vertical protruding piece 3d3, and the surface 3d1 of the corner block 3d. Additionally, on the end-side vertical plate 3c1, fitting holes 3f are formed in the vertical direction near the pair of horizontal protruding pieces 3d2.
Now, the long side wall 2A will be described with reference to FIGS. 1, 3, and 4.
The long side wall 2A has a plate-like portion 2a. An upper-end horizontal rib 2b is formed at the upper end of the long side wall 2A. A vertically long side wall-side engaging member 2c is formed at each of the opposite vertical ends of the long side wall 2A and extends in the direction of the plate-like portion 2a and outward. Fitting projecting portions 2c1 are formed at the upper end of the long side wall-side engaging portion 2c at a predetermined interval therebetween in the vertical direction and perpendicularly to the plate-like portion 2a; the fitting projecting portion 2c1 extends over the outer surface 2a1 of the plate-like portion 2a (the surface which, when the folding container is assembled into the box form, is positioned outside the folding container assembled into the box form). Moreover, an upper horizontal rib 2d is formed in the upper portion of the plate-like portion 2a at a predetermined distance from the upper-end horizontal rib 2b so as to extend to the long side wall-side engaging member 2c. 
Paired opposite central coupling vertical ribs 2e are formed at a predetermined distance from each other so as to couple a central area of the upper-end horizontal rib 2b and a central area of the upper horizontal rib 2d. The upper-end horizontal rib 2b, the upper horizontal rib 2d, the pair of opposite central coupling vertical ribs 2e, and the outer surface 2a1 of the plate-like portion 2a form a central space portion A1. 2f is a regulation portion disposed in a corner portion formed by the bottom surface of the upper-end horizontal rib 2b positioned in the central space portion A1 and a central space portion A1-side side surface of the coupling vertical rib 2e. The regulation portion 2f is formed by a horizontal regulating rib 2f1 and a vertical rib 2f2.
2g is a pair of opposite pivotal shaft supporting blocks projected, at a predetermined distance from each other, on the outer surface 2a1 of the plate-like portion 2a positioned between the regulation portion 2f and the upper horizontal rib 2d. Each of the pivotal shaft supporting blocks 2g has a prismatic block main body 2g1. A guiding inclined surface 2g2 is formed in a central portion of a corner portion formed by opposite vertical side surfaces 2g1′ of the block main body 2g1 and an outer surface 2g1′′ parallel to outer surface 2a1 of the plate-like portion 2a. A bearing hole 2g3 is formed in a central portion of the vertical side surface 2g1′ lying very close to the outer surface 2a1 of the plate-like portion 2a. 
A central guide block 2h is formed on a side surface of the central coupling vertical rib 2e positioned outside the central space portion A1, and is coupled to the outer surface 2a1 of the plate-like portion 2a and the upper surface of the upper horizontal rib 2d. A guiding through-hole H1 is drilled in the central guide block 2h and the central coupling vertical rib 2e. The guiding through-hole H1 is composed of a vertically long main guide insertion portion h1 formed in contact with the outer surface 2a1 of the plate-like portion 2a, and a driven pin insertion portion h2 formed in a central portion of a vertical surface of the main guide insertion portion h1 which lies opposite the outer surface 2a1 of the plate-like portion 2a. 
2i is an intermediate horizontal rib formed between the upper-end horizontal rib 2b and the upper horizontal rib 2d, and extending along a terminal vertical side of the plate-like portion 2a from the central guide block 2h to a vertically long, terminal vertical rib 2j formed perpendicularly to the plate-like portion 2a. Furthermore, a terminal guide block 2k is formed on an outer side surface of the terminal vertical rib 2i positioned between the paired fitting projecting portions 2c1 included in the long side wall-side engaging member 2c. A guiding through-hole H1 similar to that drilled in the central guide block 2h and the central coupling vertical rib 2e as described above is drilled in the terminal guide block 2k and the terminal vertical rib 2j. 
2m and 2n are intermediate guide blocks formed between the central guide block 2h and the terminal guide block 2k to couple the intermediate horizontal rib 2i and the upper horizontal rib 2d together. A guiding through-hole H1 similar to that drilled in the central guide block 2h and the central coupling vertical rib 2e as described above is drilled in the intermediate guide blocks 2m, 2n. The number of intermediate guide blocks formed may be one or three or more.
2p is a plate-like coupling plate coupling the tip of the intermediate horizontal rib 2i and the tip of the upper-end horizontal rib 2b which are positioned between the intermediate horizontal rib 2m and the central guide block 2h to the tip of the central coupling vertical rib 2e. Furthermore, 2q is a space portion formed in the upper portion and front surface of the central guide block 2h in order to reduce the weight of the container and to save materials.
Now, a lock member L1 composed of an operation portion L1a and a pair of lock bars L1b will be described with reference to FIGS. 5 to 9.
First, the operation portion L1a will be described mainly with reference to FIGS. 6 and 7.
The operation portion L1a is composed of a horizontally long operation main body 10 and cam portions 11 connected to opposite-end vertical side surfaces of the operation main body 10. The operation main body 10 has a bar-like upper-end horizontal beam 10a, a band-like lower-end horizontal beam 10b, and a vertical end walls 10c located at the opposite ends thereof. The upper-end horizontal beam 10a and the lower-end horizontal beam 10b are coupled together by a coupling inclined wall 10d. A rear surface (which, when the lock member L1 is attached to the long side wall 2, is positioned on the plate-like portion 2a side) 10d1 is formed as an inclined surface which, when the lock member L1 is attached to the long side wall 2, extends from the upper-end horizontal beam 10a toward the lower-end horizontal beam 10b and gradually toward the plate-like portion 2a of the long side wall 2.
The following are configured to be flush with one another: a vertical tip surface (which, when the lock member L1 is attached to the long side wall 2, is positioned farther from the plate-like portion 2a) 10a1 of the upper-end horizontal beam 10a, a vertical tip surface (which, when the lock member L1 is attached to the long side wall 2A, is positioned farther from the plate-like portion 2a) 10b1 of the lower-end horizontal beam 10b, and opposite vertical tip surfaces (which, when the lock member L1 is attached to the long side wall 2A, are positioned farther from the plate-like portion 2a) 10c1 of the vertical-end wall 10c. In this configuration, an operation space portion A2 is formed in the front surface (which, when the lock member L1 is attached to the long side wall 2A, is positioned farther from the plate-like portion 2a) of the operation main body 10 so that the operator's finger can be inserted into the operation space portion A2. An intermediate reinforcing wall 10e coupling the coupling inclined wall 10d and the lower-end horizontal beam 10b together may be formed midway between the opposite vertical end walls 10c as required to partition the operation space portion A2.
A cam portion 11 connected to the vertical end wall 10c of the operation main body 10 has a segment member 11a extending from the vertical tip surface 10c1 of the vertical end wall 10c to a vertical rear surface (which, when the lock member L1 is attached to the long side wall 2A, is positioned on the plate-like portion 2a side) 10c2 of the vertical end wall 10c, and shaped like a substantial quarter of a cylinder. The segment member 11a is bent upward from the vertical tip surface 10c1 toward the vertical rear surface 10c2 of the vertical end wall 10c. Furthermore, an inclined surface 11b inclined downward toward the vertical end wall 10c is formed on the vertical end wall 10c side of the segment member 11a. A partitioning wall 11c parallel to the vertical end wall 10c is formed in a substantial boundary area between the segment member 11a and the inclined surface 11b, and on an inner peripheral surface (which, when the lock member L1 is attached to the long side wall 2A, is positioned on the plate-like portion 2a side) 11a2 of the segment member 11a. 
A cam groove 12A is formed in the inner peripheral surface 11a2 so as to extend from a lower end 11a3 toward an upper end 11a4 of the segment member 11a and gradually toward the partitioning wall 11c. Furthermore, a pivotal shaft 13 is projected from an outer wall surface (a side surface positioned opposite the operation main body 10) 11c1 of the partitioning wall 11c. 
Additionally, a pair of downward-inclined flat-plate-like spring members S1 is provided on the bottom surface of the lower-end horizontal beam 10b so as to hang from the vicinities of the respective ends of the lower-end horizontal beam 10b toward the central portion of the lower-end horizontal beam 10b. 
Now, the lock bar L1b will be described mainly with reference to FIGS. 8 and 9.
The lock bar L1b has a horizontally long bar-like member 20. A driven pin 20c fitted into a cam groove 12A formed in an inner peripheral surface 11a2 of the segment member 11a of the above-described operation portion L1a is projected from a portion of a front plate (a horizontally long band-like plate which, when the lock member L1 is attached to the long side wall 2, is positioned farther from the plate-like portion 2a) 20a of the bar-like member 20. A diven pin 20c is positioned near one of opposite side walls 20b. 
The weight of the bar-like member 20 and the amount of material for the bar-like member 20 can be reduced by constructing the bar-like member 20 using the front plate 20a, an upper-end horizontal rib 20d extending in a horizontal direction from the upper end of the front plate 20a, and a lower-end horizontal rib 20e extending in the horizontal direction from the lower end of the front plate 20a. A space portion A3 is formed on a surface of the bar-like member 20 (which, when the block bar L1b is attached to the long side wall 2A, positioned on the plate-like portion 2a side) which is positioned on the plate-like portion 2a side. Furthermore, to reinforce the bar-like member 20, a vertical rib 20f or a horizontal rib 20g may be appropriately formed in the space portion A3.
Now, with reference to FIGS. 10 to 13, a description will be given of how the lock member L1 composed of the operation portion L1a and the pair of lock bars L1b is assembled to the long side wall 2A.
First, as shown in FIG. 10, the lock member L1 is placed such that the coupling inclined wall 10d formed in the operation portion L1a lies opposite the outer surface 2a1 of the plate-like portion 2a forming the central space portion A1 formed in the long side wall 2A. Furthermore, each of the paired lock bars L1b is placed on the side of the corresponding long side wall-side engaging member 2c of the long side wall 2A. At this time, the driven pin 20c formed in the lock bar L1b is positioned on the long side wall 2A side.
Then, each of the lock bars L1b is moved in the horizontal direction toward the corresponding long side wall-side engaging member 2c formed on the long side wall 2A so as to direct the driven 20c of the lock bar L1b to the long side wall-side engaging member 2c. The lock bar L1b is thus inserted through the guiding through-holes H1 drilled in the terminal guide block 2k and terminal vertical rib 2j formed on the long side wall 2A, and the guiding through-holes H1 drilled in the intermediate guide blocks 2m, 2n, and through the guiding through-hole H1 drilled in the central guide block 2h and the central coupling vertical rib 2e. Thus, as shown in FIG. 11, the driven pin 20c of the lock bar L1b is positioned in the central space portion A1 formed in the long side wall 2A and close to the pivotal shaft supporting block 2g. When the lock bar L1b is inserted through the guiding through-holes H1, the bar-like member 20 of the lock bar L1b is inserted through the main guide insertion portion h1. Furthermore, the driven pin 20c of the lock bar L1b is inserted through the driven pin insertion portion h2.
Then, the operation portion L1a is moved closer to the plate-like portion 2a forming the central space portion A1 formed in the long side wall 2A. Thus, the pivotal shaft 13 of the operation portion L1a is allowed to abut against the guiding inclined surface 2g2 formed on the pivotal shaft supporting block 2g formed on the plate-like portion 2a of the long side wall 2A. Moreover, the operation portion L1a is moved closer to the plate-like portion 2a of the long side wall 2A. Then, the pivotal shaft 13 of the operation portion L1a moves closer to the plate-like portion 2a of the long side wall 2A while being guided along the guiding inclined surface 2g2 of the shaft pivotal-supporting block 2g. Finally, the pivotal shaft 13 of the operation portion L1a is fitted into the bearing holes 2g3 in the respective pivotal shaft bearing blocks 2g. Furthermore, the driven pin 20c on the lock bar L1b is inserted into the lower end of the cam groove 12A formed in the inner peripheral surface 11a2 of the segment member 11a of the operation portion L1a. In this manner, as shown in FIG. 13, the lock member L1 is assembled to the long side wall 2A. When the lock member L1 is assembled to the long side wall 2A, the tip s1 of each of the spring members S1 formed on the operation portion L1a approaches or abuts against the top surface of the upper horizontal rib 2d positioned in the central space portion A1.
As described above, with the lock member L1 assembled to the long side wall 2A, a tip portion of the lock bar L1b projects beyond the terminal guide block 2k of the long side wall 2A as shown in FIG. 13, and the tip portion of the lock bar L1b is positioned between the paired fitting projecting portions 2c1 formed in the long side wall-side engaging member 2c. The end side wall 20b forming the tip of the lock bar L1b is configured so as not to project beyond the long side wall 2A. This state of the lock member L1 is hereinafter referred to as the lock state of the lock member L1.
Now, the operation of the lock member L1 assembled to the long side wall 2A will be described with reference to FIGS. 14 to 17.
When the folding container is in the assembled box form as shown in FIG. 1, the lock member L1 is in the lock state. In this state, the tip portion of the lock bar L1b is inserted in the engaging recess portion 3e formed in the short side wall-side engaging member 3c of the short side wall 3A as shown in FIG. 14. Furthermore, the fitting projecting portions 2c1 formed on the long side wall-side engaging member 2c of the long side wall 2A are fitted in the corresponding fitting holes 3f formed in the short side wall-side engaging member 3c of the short side wall 3A. Thus, the long side wall 2A is prevented from falling down toward the bottom portion 1 unless the lock state of the lock member L1 is cancelled as described below.
To fold the folding container assembled in the box form, the operator inserts the operator's finger in the operation space portion A2 of the operation portion L1a of the lock member L1 in the lock state as shown in FIGS. 12 and 13, and then pushes the lower-end horizontal beam 10b of the operation portion L1a downward. Then, the lower-end horizontal beam 10b of the operation portion L1a is pivotally moved closer to the upper horizontal rib 2d, using, as a pivotal point, the pivotal shaft 13 of the operation portion L1a fitted in the bearing holes 2g3 in the pivotal shaft supporting block 2g formed on the long side wall 2A (this pivotal moving direction is hereinafter simply referred to as the downward pivotal movement of the operation portion L1a). The downward pivotal movement of the operation portion L1a causes the spring members S1 formed on the operation portion L1a to be compressed against the elastic force thereof as shown in FIG. 16 (the following is hereinafter referred to as the compressed state of the spring member S1: the state in which the tip s1 of each of the spring members S1 is located close to the lower-end horizontal beam 10b of the operation portion L1a).
As described above, the downward pivotal movement of the operation portion L1a allows the driven pin 20c of each of the lock bars L1b inserted in the lower end of the corresponding cam groove 12A formed in the operation portion L1a to move to the upper end of the cam groove 12A. Thus, the paired lock bars L1b move closer to each other.
As described above, when the operation portion L1a is pivotally moved downward to move the paired lock bars L1b closer to each other, the tip portion of the lock bar L1b inserted in the engaging recess portion 3e formed in the short side wall-side engaging member 3c of the short side wall 3A is removed from the engaging recess portion 3e as shown in FIG. 17. Thus, with the folding container assembled in the box form, the lock state in which the lock member L1 of the long side wall 2A locks the short side wall 3A is cancelled to allow the long side wall 2A to be brought down toward the bottom portion 1. Then, the short side wall 3A is brought down toward the bottom portion 1 to allow the folding container to be folded.
As described above, when the lock state established between the long side wall 2A and the short side wall 3A via the lock member L1 is cancelled, the upper-end horizontal beam 10a of the operation portion L1a is pivotally moved closer to the upper-end horizontal rib 2b by the elastic restoring force of the spring members S1, the pivotal shaft 13 of the operation portion L1a fitted in the bearing holes 2g3 in the pivotal shaft supporting block 2g formed on the long side wall 2A (this pivotal moving direction is hereinafter simply referred to as the upward pivotal movement of the operation portion L1a).
As described above, the locking and unlocking between the long side wall 2A and the short side wall 3A via the lock member L1 is performed by pivotally moving the operation portion L1a downward (the unlocking between the long side wall 2A and the short side wall 3A) or upward (locking between the long side wall 2A and the short side wall 3A) using, as a pivotal point, the pivotal shaft 13 of the operation portion L1a fitted in the bearing holes 2g3 in the pivotal shaft supporting block 2g formed on the long side wall 2A. Thus, even if the operator pushes a part of the lower-end horizontal beam 10b of the operation portion L1a which the part is positioned on the vertical-end wall 10c side, the operation portion L1a is prevented from being tilted. Therefore, the pair of lock bars L1b moved backward (toward the central portion of the long side wall 2A) by the downward pivotal movement of the operation portion L1a is simultaneously and reliably moved in the horizontal direction. Thus, the long side wall-side engaging members 2c arranged at the respective ends of the long side wall 2A can be reliably unlocked from the short side wall-side engaging members 3c arranged at the respective ends of the short side wall 3A via the lock member L1. This enables the solution of the problem with the conventional folding container that one of the lock bars L1b fails to be removed from the engaging recess portion 3e of the corresponding short side wall-side engaging members 3c of the short side wall 3A, preventing the long side wall 2A from being brought down toward the bottom portion 1.
Furthermore, even when the elastic restoring force of the spring members S1 causes the operation portion L1a to move pivotally upward, the pair of lock bars L1b moved forward (toward the terminal vertical rib 2j of the long side wall 2A) by the upward pivotal movement of the operation portion L1a is simultaneously and reliably moved.
Now, another embodiment of the present invention will be described with reference to FIGS. 18 to 21.
The present embodiment uses coil-like spring members (hereinafter simply referred to as coil springs) instead of the flat plate-like spring members S1 hanging from the bottom surface of the lower-end horizontal beam 10b of the operation main body 10 included in the operation portion L1a in the above-described embodiment. Furthermore, in order to allow such coil springs S2 to be used, the operation portion L1a is modified as follows.
As shown in FIG. 19, in the present embodiment, as described above, the flat plate-like spring members S1 are omitted which hang from the lower-end horizontal beam 10b of the operation main body 10 included in the operation portion L1a in the above-described embodiment. In the present embodiment, a coil spring supporting plate 14 is formed in a corner portion formed by the partitioning wall 11c and the lower-end horizontal beam 10b of the operation main body 10. Furthermore, a coil spring supporting pin 14a is projected from a rear surface (which, when the lock member L1 is attached to the long side wall 2A, is positioned on the plate-like portion 2a side) of the coil supporting plate 14 so that one end of the coil spring S2 can be inserted around the coil spring supporting pin 14a. 
As shown in FIG. 18, one end of the coil spring S2 is inserted around the coil spring supporting pin 14a. Then, as in the above-described embodiment, the operation portion L1a included in the lock member L1 is placed opposite the outer surface 2a1 of the plate-like portion 2a of the long side wall 2A. Thereafter, the operation portion L1a is moved closer to the long side wall 2A and thus assembled to the long side wall 2A as in the case of the above-described embodiment.
As shown in FIG. 20, with the lock member L1 in the lock state, the coil springs S2 are expanded. Furthermore, when the operation portion L1a is pivotally moved downward for unlocking, the coil springs S2 are compressed as shown in FIG. 21. When the operator takes the operator's hand off the operation portion L1a, the operation portion L1a is pivotally moved upward by the restoration force of the coil springs S2.
Now, another embodiment of the present invention will be described with reference to FIGS. 22 to 24.
In the above-described embodiments, as shown in FIG. 7, the cam groove 12A formed in the inner peripheral surface 11a2 of the segment member 11a included in the lock member L1 extends from the lower end 11a3 to upper end 11a4 of the segment member 11a and gradually toward the partitioning wall 11c. However, in the present embodiment, a cam groove 12B is formed so as to extend from the lower end 11a3 to upper end 11a4 of the segment member 11a and gradually away from the partitioning wall 11c. 
Furthermore, when the operation portion L1a is pivotally moved upward, the driven pin 20c of the lock bar L1b included in the lock member L1 is inserted into the lower end of the cam grove 12B. In this state, when the operation portion L1a is pivotally moved downward, the driven pin 20c of the lock bar L1b is moved to the upper end of the cam groove 12B. Thus, the paired lock bars L1b move away from each other.
As shown in FIG. 23, this folding container is applicable to a folding container of a type in which an elastic piece E1 having a projecting portion e1 projected therefrom is formed on the plate-like portion 3a of the short side wall 3B. Since a folding container of this type is well known (for example, the Unexamined Japanese Patent Application Publication (Tokkai) No. 2004-51199), the configuration of the folding container itself is omitted.
As shown in FIG. 23, with the operation portion L1a pivotally moved upward (lock state), the paired lock bars L1b are prevented from abutting against the elastic piece E1. Furthermore, with the operation portion L1a pivotally moved downward, the paired lock bars L1b move away from each other to allow the end side wall 20b forming the tip of the lock bar L1b to abut against the projecting portion e1 of the elastic piece E1. Thus, as shown in FIG. 24, the elastic piece E1 is elastically deformed outward, thus in the folding container assembled in the box form, unlocking, from the elastic piece E1, a locking piece (not shown in the drawings) formed on the long side wall-side engaging member 2c of the long side wall 2A placed between the short side wall-side engaging member 3c of the short side wall 3B and the projecting portion e1 of the elastic piece E1. As a result, the long side wall 2A can fall down to the bottom portion 1.
Now, yet another embodiment will be described with reference to FIGS. 25 to 29.
The long side wall 2B has a plate-like portion 200a similar to the plate-like portion 2a in the above-described embodiment. An upper-end horizontal rib 200b similar to the upper-end horizontal rib 2b in the above-described embodiment is formed at the upper end of the long side wall 2B. Furthermore, a long side wall-side engaging member 200c is formed at each of the opposite vertical ends of the long side wall 2B so as to extend in the direction of the plate-like portion 200a and outward from a terminal vertical rib 200j similar to the terminal vertical rib 2j in the above-described embodiment. Fitting projecting portions 200c1 are formed at the upper end of the long side wall-side engaging member 200c at a predetermined distance from each other and substantially perpendicularly to the plate-like portion 200a so as to extend toward an outer surface (which, when the folding container is assembled into a box form, is positioned outside the assembled folding container) 200a1 of the plate-like portion 200a. Moreover, an upper horizontal rib 200d is formed on the upper portion of the plate-like portion 200a at a predetermined distance from the upper-end horizontal rib 200b so as to connect the terminal vertical ribs 200j together.
Paired opposite central coupling vertical ribs 200e are formed at a predetermined distance from each other so as to couple a central area of the upper-end horizontal rib 200b and a central area of the upper horizontal rib 200d together. A central space portion A10 is formed by the upper-end horizontal rib 200b, the upper horizontal rib 200d, the opposite paired central coupling vertical ribs 200e, and the outer surface 200a1 of the plate-like portion 200a. 
A lever slit 200e1 serving as a lever support point for a lock bar L100b included in a lock bar L100 described below is drilled in the central coupling vertical rib 200e. 
Furthermore, intermediate-end-side coupling vertical ribs 200m coupling the upper-end horizontal rib 200b and the upper horizontal rib 200d together is formed closer to the respective terminal vertical ribs 200j than the corresponding central coupling vertical ribs 200e. A slit 200m1 is drilled in each of the intermediate end-side coupling vertical ribs 200m so that the lock bar L100b included in the lock member L100 described below can be moved through the slit 200m1 in the vertical direction.
Moreover, a slit 200 j1 is also drilled at the upper end of the terminal vertical rib 200j so that the lock bar L100b included in the lock member L100 described below can be moved through the slit 200j1 in the vertical direction.
Now, the lock member L100 composed of the operation portion L100a and the lock bar L100b will be described with reference to FIGS. 26 and 27.
The operation portion L100a has a rectangular plate-like base portion 100a, and paired operation bars 100b provided on the bottom surface of the plate-like base portion 100a along a long-side end surface 10a1 of the plate-like base portion 100a and at a predetermined distance from each other so as to extend in the vertical direction. The operation bar 100b has a columnar portion 100b1 connected to the bottom surface of the plate-like base portion 100a, and a spherical operation end 100b2 formed at the tip of the columnar portion 100b1. The outer diameter of the operation end 100b2 is formed to be larger than the thickness of the columnar portion 100b1. Furthermore, a pivotal shaft 100a3 is projected from opposite short-side end surface 100a2 of the plate-like base portion 100a. 
The lock bar L100b is composed of a flat prismatic block base portion 100c, and a vertical, flat plate-like plate portion 100d coupled to one of opposite vertical surfaces 100c1 of the block base portion 100c. Furthermore, a plate-like spring member S10 inclined toward the plate portion 100d hangs from the bottom surface of each of the block base portions 100c. 
A cam groove 100e is formed in the upper portion of each of the block base portion 100c at a position located opposite the operation plate portion 100d, so as to extend from one of opposite long-side vertical surfaces 100c2 of the block base portion 100c toward the other long-side vertical surface 100c2 but not to reach the other long-side vertical surface 100c2. The cam groove 100e is formed parallel to the short-side vertical surface 100c1 of the block base portion 100c. 
As shown in FIG. 27, the cam groove 100e is composed an operation end fitting portion 100e2 formed in the lower portion of the cam groove 100e and in which the operation end 100b2 of the operation bar 100b can be fitted, and a columnar fitting portion 100e1 in which the columnar portion 100 b1 of the operation bar 100b is fitted and guided. The cam groove 100e is formed so as to appear a reversed T-shape as viewed from the long-side vertical surface 100c2.
Support pieces 200f are provided in a central region of the bottom surface of the upper-end horizontal rib 200b of the long side wall 2B at a predetermined distance from each other so as to hang therefrom orthogonally to the longitudinal direction of the upper-end horizontal rib 200b. A pivotal-supporting hole 200f1 is formed in each of the support pieces 200f so that the pivotal shaft 100a3 projected from the above-described operation portion L100a is fitted and pivotally supported in the pivotal-supporting hole 200f1.
To assemble the lock member L100 to the long side wall 2B, the plate portion 100d of the lock bar L100b is inserted, from the central coupling vertical rib 200e side, firstly through the lever slit 200e1 drilled in the central coupling vertical rib 200e. The plate portion 100d is thereafter inserted through the slit 200m1 drilled in the intermediate-end coupling vertical rib 200m. The plate portion 100d is further inserted through the slit 200j1 drilled in the terminal vertical rib 200j. Thus, the plate portion 100d is inserted through the lever slit 200e1 drilled in the central coupling vertical rib 200e, also through the slit 200m1 drilled in the intermediate-end coupling vertical rib 200m, and further through the slit 200j1 drilled in the terminal vertical rib 200j. Then, the block base portions 100c of the paired lock bar L100b are arranged in the central space portion A10 formed by the upper-end horizontal rib 200b, the upper horizontal rib 200d, the opposite paired central coupling vertical ribs 200e, and the outer surface 200a1 of the plate-like portion 200a. In this state, the tip of the each of the spring members S10 abuts against or is positioned close to the upper horizontal rib 200d. 
Then, the operation portion L100a is moved closer to the outer surface 200a1 of the plate-like portion 200 of the long side wall 2B. Thus, the operation end 100b2 of the operation bar 100b is inserted into the operation end fitting portion 100e2 of the cam groove 100e. Furthermore, the columnar portion 100b1 of the operation bar 100b is inserted into the columnar fitting portion 100e1 of the cam groove 100e. Thus, the lock member L100 is assembled to the long side wall 2B. As described above, when the lock member L100 is assembled to the long side wall 2B, the operation bar 100b of the operation portion L100a is positioned in an opening side of the cam groove 100e. Furthermore, the pivotal shaft 100a3 projected from the opposite short-side end surfaces 100a2 of the plate-like base portions 100a of the operation portion L100a is fitted into the pivotal-supporting holes 200f1 formed in the opposite surfaces of the support pieces 200f provided on the bottom surface of the upper-end horizontal rib 200b of the long side wall 2B at the predetermined intervals from each other so as to hang downward.
As described above, when the lock member L100 is assembled to the long side wall 2B, the operation end 100b2 of each of the lock bars L100b abuts against or is positioned close to the bottom surface 100e1′ of the operation end fitting portion 100e2 of the cam groove 100e. Furthermore, as shown in FIGS. 25 and 28, the plate portions 100d of the lock bar L100b are horizontally held. In this state, the tip of each of the spring members S10 abuts against or is positioned close to the upper horizontal rib 200d. 
The above-described state is the lock state in which each of the lock bars L100b of the lock member L100 is locked in the locking portion (not shown in the drawings) formed in the short wall-side engaging member 3c of the short side wall 3A.
To cancel the lock state between the long side wall 2B and the short side wall 3A by the lock member L100, the operation portion L100a of the lock member L100 which is positioned in upward state (lock state) is pivotally moved downward using, as a pivotal point, the pivotal-supporting holes 200f1 formed in the support pieces 200f and the pivotal shaft 100a3 of the operation portion L100a fitted into the pivotal-supporting holes 200f1.
As described above, when the operation portion L100a of the lock member L100 is moved downward, the operation bars 100b of the operation portion L100a move toward the plate-like portion 2a of the long side wall 2B. Then, as shown in FIG. 29, the tip portion of each of the lock bars L100b moves upward using, as a lever support point, the horizontal lower end forming the lever slit 200e1 drilled in the central coupling vertical rib 200e and serving as a lever support point.
As described above, moving the tip portion of each of the lock bars L100b upward allows cancellation of the lock state between the locking piece (not shown in the drawings) formed on the short side wall-side engaging member 3c of the short side wall 3A and the lock bar L100b attached to the long side wall 2B. Thus, the long side wall 2B falls down toward the bottom portion 1. This type of folding container is well known (see, for example, the Unexamined Japanese Patent Application Publication (Tokkai) No. 2003-40263).
The embodiment shown in FIG. 30 corresponds to the above-described embodiment in which the paired lock bars L100b are integrated into the appropriate components. In this configuration, pivotally moving the operation portion L100a downward allows the lock bars L100b to lower while remaining parallel to the upper horizontal rib 200d. Thus, a slit 200e2 is drilled in each of the central coupling vertical ribs 200e so that the corresponding lock bar L100b can move up and down through the slit 200e2; the slit 200e2 is similar to the slit 200m1 formed in the intermediate end-side coupling vertical rib 200m and the slit 200j1 formed in the terminal vertical rib 200j. 
In the configuration of the above-described embodiment, the long side wall 2A and the short side wall 3A are unlocked by pivotally moving the operation portions L1a, L100a downward. The long side wall 2A and the short side wall 3A are locked by pivotally moving the operation portions L1a, L100a upward. However, in an alternative configuration, the long side wall 2A and the short side wall 3A may be unlocked by pivotally moving the operation portions L1a, L100a upward, and the long side wall 2A and the short side wall 3A may be locked by pivotally moving the operation portions L1a, L100a downward.

## Claims

1. A folding container having first opposite side walls which, when the folding container is in an assembled box form, are brought down firstly toward a bottom portion and second opposite side walls which are brought down secondly toward the bottom portion after the first opposite side walls have been brought down, the folding container being characterized in that
a lock member comprising an operation portion and a lock bar is disposed on each of the first opposite side walls to be brought down firstly toward the bottom portion, and
said operation portion being pivotally mounted in each of the first opposite side walls to be brought down firstly toward the bottom portion around a fixed pivot axis when said first opposite side walls are in an upright fixed position, using pivot pins pivotally supported within bearing holes, and
to allow cancellation of a locked state between the lock member and each of the second opposite side walls to be brought down secondly toward the bottom portion, the operation portion is, when the lock member is in the locked state, pivotally moved around said fixed pivot axis upward or downward.

2. The folding container of claim 1, wherein said operation portion has pivot pins that are received within bearing holes formed in said first opposite side wall.

3. The folding container of claim 1, wherein pivotal movement of said operation portion around said fixed pivot axis is transmitted via a cam mechanism to horizontal movement of two opposing lock bars disposed on opposite sides of said operation portion.

4. The folding container of claim 2, wherein pivotal movement of said operation portion around said fixed pivot axis is transmitted via a cam mechanism to horizontal movement of two opposing lock bars disposed on opposite sides of said operation portion.

5. The folding container of claim 1, wherein pivotal movement of said operation portion around said fixed pivot axis is biased via a spring in a first direction to cause said lock bar to move to said locked state and wherein said operation portion is configured to be manually pivoted in a direction opposite to said first direction against a force of said spring to cause said lock bar to move to an unlocked state.

6. The folding container of claim 2, wherein pivotal movement of said operation portion around said fixed pivot axis is biased via a spring in a first direction to cause said lock bar to move to said locked state and wherein said operation portion is configured to be manually pivoted in a direction opposite to said first direction against a force of said spring to cause said lock bar to move to an unlocked state.

7. The folding container of claim 3, wherein pivotal movement of said operation portion around said fixed pivot axis is biased via a spring in a first direction to cause said lock bar to move to said locked state and wherein said operation portion is configured to be manually pivoted in a direction opposite to said first direction against a force of said spring to cause said lock bar to move to an unlocked state.

8. The folding container of claim 4, wherein pivotal movement of said operation portion around said fixed pivot axis is biased via a spring in a first direction to cause said lock bar to move to said locked state and wherein said operation portion is configured to be manually pivoted in a direction opposite to said first direction against a force of said spring to cause said lock bar to move to an unlocked state.