Patent Publication Number: US-9883713-B2

Title: Footwear

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of priority and is a Continuation application of the prior International Patent Application No. PCT/JP2015/052598, with an international filing date of Jan. 29, 2015, which designated the United States, and is related to the Japanese Patent Application No. 2014-018112 filed Feb. 1, 2014, and Japanese Patent Application No. 2014-239401 filed Nov. 27, 2014, the entire disclosures of all applications are expressly incorporated by reference in their entirety herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a footwear formed by an outsole portion and an upper portion. In particular, the present invention relates to attachable/detachable structure of the upper portion. 
     2. Description of Related Art 
     In Patent Document 1 below, a mechanism of detachably attaching a strap portion ( 40 ) to form an upper portion of a sandal is disclosed. In this mechanism, a projected locking portion ( 20 ) formed on an outsole ( 10 ) is inserted into holes formed on both ends of the strap portion ( 40 ). The strap portion ( 40 ) is prevented from being detached by stopper claws ( 21  or  25 A) formed on the locking portion ( 20 ). 
     Patent document 1: Japanese utility model registration No. 3083693 
     BRIEF SUMMARY OF THE INVENTION 
     However, only the stopper claws ( 21  or  25 A) disclosed in Patent Document 1 are not strong enough for preventing the detachment. In addition, when inserting the strap portion ( 40 ), both ends of the strap portion ( 40 ) should be moved downward toward the locking portion ( 20 ) formed on the outsole ( 10 ). Because of this, a large space is needed on the outsole ( 10 ) in a vertical direction. Thus, the mechanism could not be applied to a footwear having a small thickness. 
     The present invention provides a footwear capable of sufficiently preventing the detachably attached upper portion from being detached although the thickness of the footwear can be kept smaller. 
     One embodiment of the present invention provides a footwear, comprising: 
     an outsole portion having a portion to be in contact with the ground; and 
     an upper portion having a portion crossing over instep of foot, the upper portion being attachable to and detachable from the outsole portion; wherein 
     a plurality of insertion pieces made of a material having elasticity is formed on a periphery of the upper portion, 
     a recess is formed on a center of an upper surface of the outsole portion, insertion holes are formed on the outsole portion, the insertion holes being directed from an outer periphery of the outsole portion to the recess located at the center, 
     a groove is formed between each of the insertion holes so that a joint portion connecting each of the insertion pieces is fitted into the groove when the upper portion is attached to the outsole portion, the groove being directed from the outer periphery to an inner side of the outsole portion, and 
     the upper portion is attachable to the outsole portion by inserting the insertion pieces into the insertion holes in a direction toward the recess located at the center. 
     In another embodiment of the present invention, 
     a locking hole is formed on each of the insertion pieces, and 
     locking protrusions are formed at a bottom of the recess formed on the center of the upper surface of the outsole portion, the locking protrusions being located at a position enabling to lock the locking hole in a state that each of the insertion pieces is penetrated through into the insertion holes. 
     In another embodiment of the present invention, 
     an insole portion attached to the upper surface of the outsole portion is further provided, wherein 
     a locking hole is formed on each of the insertion pieces, 
     a fitting hole is formed at a bottom of the recess formed on the center of the upper surface of the outsole portion, the fitting hole being located at a position to be overlapped with the locking hole in a state that each of the insertion pieces is penetrated through the insertion holes, and 
     a fitting protrusion is formed on the insole portion, the fitting portion being located at a position enabling to pass through the locking hole and to fit with the fitting hole in a state that the upper portion and the insole portion are attached to the outsole portion. 
     In another embodiment of the present invention, 
     a locking claw or a locking constriction is formed on a tip of each of the insertion pieces, and 
     a lock receiving portion is formed at a bottom of the recess formed on the center of the upper surface of the outsole portion, the lock receiving portion being located at a position enabling to lock the locking claw or the locking constriction in a state that each of the insertion pieces is penetrated through the insertion holes. 
     In another embodiment of the present invention, 
     an insole portion attached to the upper surface of the outsole portion is further provided, wherein 
     a locking claw or a locking constriction is formed on a tip of each of the insertion pieces, and 
     a lock receiving portion is formed on the insole portion, the lock receiving portion being located at a position enabling to lock the locking claw or the locking constriction in a state that the upper portion and the insole portion are attached to the outsole portion. 
     In another embodiment of the present invention, 
     a locking claw is formed on a tip of each of the insertion pieces, and 
     each of the insertion pieces has a shape to be contracted during when the insertion pieces are inserted into the insertion holes and to be expanded after penetrated through the insertion holes so that the insertion holes function as a lock receiving portion. 
     In another embodiment of the present invention, 
     a dimension of each of the insertion holes is specified so that the insertion pieces can be inserted into the insertion holes after when the insertion pieces becomes smaller in width by being in contacted with the insertion holes and pushed by the insertion holes from both lateral ends of the insertion pieces to shrink the locking hole. 
     In another embodiment of the present invention, 
     each of the insertion pieces is sharp-edged at a front end and tongue-shaped, and 
     the locking hole is formed in a long shape longitudinally along a direction of inserting the insertion pieces. 
     In another embodiment of the present invention, 
     each of the insertion pieces is sharp-edged at a front end and tongue-shaped, and 
     the locking hole is sharp-edged at a front end and/or a rear end in a direction of inserting the insertion pieces. 
     In another embodiment of the present invention, 
     each of the locking protrusions or the lock receiving portion is inclined upward in a slope shape toward a front side in a direction of inserting the insertion pieces. 
     In another embodiment of the present invention, 
     the fitting protrusion and the fitting hole are formed in a locking shape. 
     Another embodiment of the present invention provides a footwear, comprising: 
     an outsole portion having a portion to be in contact with the ground; and 
     an upper portion having a portion crossing over instep of foot, the upper portion being attachable to and detachable from the outsole portion; wherein 
     a plurality of insertion pieces made of a material having elasticity is formed on a periphery of the upper portion, 
     a recess is formed on a center of an lower surface of the outsole portion insertion holes are formed on the outsole portion, the insertion holes being directed from an outer periphery of the outsole portion to the recess located at the center, 
     a groove is formed between each of the insertion holes so that a joint portion connecting each of the insertion pieces is fitted into the groove when the upper portion is attached to the outsole portion, the groove being directed from the outer periphery to an inner side of the outsole portion, and 
     the upper portion is attachable to the outsole portion by inserting the insertion pieces into the insertion holes in a direction toward the recess located at the center. 
     In another embodiment of the present invention, 
     a locking hole is formed on each of the insertion pieces, and locking protrusions are formed at a bottom of the recess formed on the center of the lower surface of the outsole portion, the locking protrusions being located at a position enabling to lock the locking hole in a state that each of the insertion pieces is penetrated through the insertion holes. 
     In another embodiment of the present invention, 
     a back lid to be attached to the lower surface of the outsole portion is further provided, wherein 
     a locking hole is formed on each of the insertion pieces, 
     a fitting hole is formed at a bottom of the recess formed on the center of the lower surface of the outsole portion, the fitting hole being located at a position to be overlapped with the locking hole in a state that each of the insertion pieces is penetrated through the insertion holes, and 
     a fitting protrusion is formed on the back lid, the fitting portion being located at a position enabling to pass through the locking hole and to fit with the fitting hole in a state that the upper portion and the back lid are attached to the outsole portion. 
     In another embodiment of the present invention, a locking claw or a locking constriction is formed on a tip of each of the insertion pieces, and 
     a lock receiving portion is formed at a bottom of the recess formed on the center of the lower surface of the outsole portion, the lock receiving portion being located at a position enabling to lock the locking claw or the locking constriction in a state that each of the insertion pieces is penetrated through the insertion holes. 
     In another embodiment of the present invention, 
     a back lid to be attached to the lower surface of the outsole portion is further provided, wherein 
     a locking claw or a locking constriction is formed on a tip of each of the insertion pieces, and 
     a lock receiving portion is formed on the back lid, the lock receiving portion being located at a position enabling to lock the locking claw or the locking constriction in a state that the upper portion and the back lid are attached to the outsole portion. 
     In another embodiment of the present invention, 
     a locking claw is formed on a tip of each of the insertion pieces, and 
     each of the insertion pieces has a shape to be contracted during when the insertion pieces are inserted into the insertion holes and to be expanded after penetrated through the insertion holes so that the insertion holes function as a lock receiving portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A to 1E and 1B ′ are exploded views of a footwear of the first embodiment of the present invention.  FIG. 1A  is a perspective view of an insole portion where a foot is in contact with the footwear.  FIG. 1B  is a perspective view of an upper portion having a portion crossing over instep of foot.  FIG. 1B ′ is a perspective view showing a state just before attaching the upper portion shown in  FIG. 1B .  FIG. 1C  is a perspective view of an outsole portion to which the upper portion shown in  FIG. 1B ′ is attachable.  FIG. 1D  is a perspective view showing a state that the upper portion shown in  FIG. 1B ′ is attached to the outsole portion shown in  FIG. 1C .  FIG. 1E  is a perspective view showing a state that the insole portion shown in  FIG. 1A  is attached to  FIG. 1D . 
         FIG. 2A  is a plan view of  FIG. 1A .  FIG. 2B  is a plan view of  FIG. 1B .  FIG. 2C  is a plan view of  FIG. 1C .  FIG. 2D  is a plan view of  FIG. 1D .  FIG. 2D ′ is a plan view partly seen through  FIG. 2D .  FIG. 2E  is a plan view of  FIG. 1E . 
       FIGS.  3 F 1  to  3 F 4  and  3 D 1  to  3 D 4  are drawings for explaining a mechanism for attaching the upper portion to the outsole portion concerning the footwear of one embodiment of the present invention where a locking hole is formed on each of the insertion pieces. FIGS.  3 F 1  to  3 F 4  are plan views explaining a motion of attaching the insertion pieces of the upper portion shown in  FIG. 1B  to the insertion holes of the outsole portion shown in  FIG. 1C . FIGS.  3 D 1  to  3 D 4  are cross-sectional views explaining a motion of attaching the insertion pieces of the upper portion shown in  FIG. 1B  to the insertion holes of the outsole portion shown in  FIG. 1C . FIGS.  3 F 1  and  3 D 1  show a state before the insertion. FIGS.  3 F 2 ,  3 D 2 ,  3 F 3  and  3 F 4  show a state during the insertion. FIGS.  3 F 4  and  3 D 4  show a state after finishing the insertion. 
         FIGS. 4A to 4C ,  4 D 1   a  to  4 D 3   e  and  4 E are cross-sectional views of the footwear concerning the first to fourth embodiments of the present invention.  FIGS. 4A to 4A and 4E  are cross-sectional views of each portion in the first embodiment.  FIG. 4A  is a cross-sectional view of the insole portion,  FIG. 4B  is a cross-sectional view of the upper portion, and  FIG. 4C  is a cross-sectional view of the outsole portion before the insertion.  FIG. 4E  is a cross-sectional view after finishing the attachment. FIGS.  4 D 1   a  to  4 D 1   c  and  4 D 1   e  are cross-sectional views of each portion in the second embodiment. FIG.  4 D 1   a  is a cross-sectional view of the insole portion,  4 D 1   b  is a cross-sectional view of the upper portion and  4 D 1   c  is a cross-sectional view of the outsole portion before the insertion. FIG.  4 D 1   e  is a cross-sectional view after finishing the attachment. FIGS.  4 D 2   a  to  4 D 2   c  and  4 D 2   e  are cross-sectional views of each portion in the third embodiment. FIG.  4 D 2   a  is a cross-sectional view of the insole portion,  4 D 2   b  is a cross-sectional view of the upper portion and  4 D 2   c  is a cross-sectional view of the outsole portion before the insertion. FIG.  4 D 2   e  is a cross-sectional view after finishing the attachment. FIGS.  4 D 3   a  to  4 D 3   c  and  4 D 3   e  are cross-sectional view of each portion in the fourth embodiment. FIG.  4 D 3   a  is a cross-sectional view of a back lid, FIG.  4 D 3   b  is a cross-sectional view of the upper portion and FIG.  4 D 3   c  is a cross-sectional view of the outsole portion before the insertion. FIG.  4 D 3   e  is a cross-sectional view after finishing the attachment. 
         FIGS. 5A to 5E and 5A ′ to  5 E′ are exploded views of a footwear of the fifth embodiment of the present invention.  FIG. 5A  is a perspective view of an insole portion where a foot is in contact with the footwear.  FIG. 5B  is a perspective view of an upper portion having a portion crossing over instep of foot.  FIG. 5C  is a perspective view of an outsole portion to which the upper portion shown in  FIG. 5B  is attachable.  FIG. 5D  is a perspective view showing a state that the upper portion shown in  FIG. 5B  is attached to the outsole portion shown in  FIG. 5C .  FIG. 5E  is a perspective view showing a state that the insole portion shown in  FIG. 5A  is attached to  FIG. 5D .  FIG. 5A ′ is a cross-sectional view of  FIG. 5A .  FIG. 5B ′ is a cross-sectional view of  FIG. 5B .  FIG. 5C ′ is a cross-sectional view of  FIG. 5C .  FIG. 5E ′ is a cross-sectional view of  FIG. 5E .  FIG. 5D ′ is a plan view partly seen through  FIG. 5D . 
         FIGS. 6A to 6E, 6A ′ to  6 E′ and  6 E″ are exploded views of a footwear of the sixth embodiment of the present invention.  FIG. 6A  is a perspective view of an insole portion where a foot is in contact with the footwear.  FIG. 6B  is a perspective view of an upper portion having a portion crossing over instep of foot.  FIG. 6C  is a perspective view of an outsole portion to which the upper portion shown in  FIG. 6B  is attachable.  FIG. 6D  is a perspective view showing a state that the upper portion shown in  FIG. 6B  is attached to the outsole portion shown in  FIG. 6C .  FIG. 6E  is a perspective view showing a state that the insole portion shown in  FIG. 6A  is attached to  FIG. 6D .  FIG. 6A ′ is a cross-sectional view of  FIG. 6A .  FIG. 6B ′ is a cross-sectional view of  FIG. 6B .  FIG. 6C ′ is a cross-sectional view of  FIG. 6C .  FIG. 6E ′ is a cross-sectional view of  FIG. 6E .  FIG. 6E ″ is a cross-sectional view showing a portion between the insertion pieces shown in  FIG. 6E .  FIG. 6D ′ is a plan view partly seen through  FIG. 6D  except for the convex/concave locking shape. 
         FIGS. 7A to 7E, 7A ′ to  7 E′ and  7 E″ are exploded views of a footwear of the seventh embodiment of the present invention.  FIG. 7A  is a perspective view of an insole portion where a foot is in contact with the footwear.  FIG. 7B  is a perspective view of an upper portion having a portion crossing over instep of foot.  FIG. 7C  is a perspective view of an outsole portion to which the upper portion shown in  FIG. 7B  is attachable.  FIG. 7D  is a perspective view showing a state that the upper portion shown in  FIG. 7B  is attached to the outsole portion shown in  FIG. 7C .  FIG. 7E  is a perspective view showing a state that the insole portion shown in  FIG. 7A  is attached to  FIG. 7D .  FIG. 7A ′ is a cross-sectional view of  FIG. 7A .  FIG. 7B ′ is a cross-sectional view of  FIG. 7B .  FIG. 7C ′ is a cross-sectional view of  FIG. 7C .  FIG. 7E ′ is a cross-sectional view of  FIG. 7E .  FIG. 7E ″ is a cross-sectional view showing a portion between the insertion pieces shown in  FIG. 7E .  FIG. 7D ′ is a plan view partly seen through  FIG. 7D  except for the convex/concave locking shape. 
       FIGS.  8 F 1  to  8 F 4  and  8 D 1  to  8 D 4  are drawings for explaining a mechanism for attaching the upper portion to the outsole portion concerning the footwear of the eighth embodiment of the present invention. FIGS.  8 F 1  to  8 F 4  are plan views explaining a motion of inserting the insertion pieces of the upper portion into the insertion holes of the outsole portion and then inserting into the lock receiving portion. FIGS.  8 D 1  to  8 D 4  are cross-sectional views explaining a motion of inserting the insertion pieces of the upper portion into the insertion holes of the outsole portion and then inserting into the lock receiving portion. FIGS.  8 F 1  and  8 D 1  show a state before the insertion. FIGS.  8 F 2 ,  8 D 2 ,  8 F 3  and  8 F 4  show a state during the insertion. FIGS.  8 F 4  and  8 D 4  show a state after finishing the insertion. 
         FIGS. 9G, 9G ′ and  9 E are cross-sectional views of a footwear of the seventh embodiment of the present invention.  FIGS. 9H, 9H ′ and  9 E′ are cross-sectional views of a footwear of the ninth embodiment of the present invention.  FIGS. 9I, 9I ′ and  9 E″ are cross-sectional views of a footwear of the tenth embodiment of the present invention.  FIGS. 9G, 9H and 9I  are cross-sectional views cut at the rear side of a locking claw of each of the insertion pieces vertically to an insertion direction.  FIGS. 9G ′,  9 H′ and  9 I′ are cross-sectional views cut at the locking claw of each of the insertion pieces vertically to the insertion direction.  FIGS. 9E, 9E ′ and  9 E″ are cross-sectional views cut at the insertion pieces in the insertion direction. 
         FIGS. 10A to 10E  are exploded views of the footwear of the eleventh embodiment.  FIGS. 10D ′,  10 E′ and  10 F 1  to  10 F 3  are drawings explaining an attachment process of the upper portion.  FIG. 10A  is a perspective view of an insole portion where a foot is in contact with the footwear.  FIG. 10B  is a perspective view of an upper portion having a portion crossing over instep of foot.  FIG. 10C  is a perspective view of an outsole portion to which the upper portion shown in  FIG. 10B  is attachable.  FIG. 10D  is a perspective view showing a state that the upper portion shown in  FIG. 10B  is attached to the outsole portion shown in  FIG. 10C .  FIG. 10E  is a perspective view showing a state that the insole portion shown in  FIG. 10A  is attached to  FIG. 10D .  FIGS. F1  to F 3  are drawings explaining a process of inserting the insertion pieces into the insertion holes.  FIG. 10E ′ is a cross-sectional view of  FIG. 10E .  FIG. 10D ′ is a plan view partly seen through  FIG. 10D  except for the convex/concave locking shape. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The footwear of the first embodiment of the present invention is shown in  FIGS. 1A to 1E, 1D ′,  2 A to  2 E and  2 D′. An embodiment having the locking hole on each of the insertion pieces is partly explained in FIGS.  3 F 1  to  3 F 4  and  3 D 1  to  3 D 4 . The cross-sectional views of the footwear of the first to fourth embodiments are shown in  FIGS. 4A to 4C ,  4 D 1   a  to  4 D 3   e  and  4 E. 
     As shown in  FIGS. 1A to 1E, 1D ′,  2 A to  2 E and  2 D′, a footwear  1  of the first embodiment is a sandal. An upper portion  5  is detachably attached to an outsole portion  3  and then a detachable mechanism  7  is covered with an insole portion  9 . Thus, the upper portion  5  is replaceable. 
     As shown in  FIG. 1C , the outsole portion  3  forms a lower portion of the footwear  1 , and the outsole portion  3  has a portion  11  to be in contact with the ground. 
     As shown in  FIG. 1B  and  FIG. 2B , the upper portion  5  can be attached to and detached from the outsole portion  3 , and the upper portion  5  has a portion  13  crossing over instep of foot. For attaching and detaching the upper portion  5 , a plurality of insertion pieces  15  is formed on an entire periphery of the upper portion  5 . 
     The insertion pieces  15  are integrally formed with the upper portion  5  by the same material having strength and elasticity. For example, synthetic resin is used. A locking hole  19  is formed at an approximately center of a tip of each of the insertion pieces  15 . The insertion pieces  15  are formed on a periphery of the upper portion  5  and aligned along a frame portion  17 . The insertion pieces  15  are arranged approximately horizontally toward an inner side of the upper portion  5 . When inserting the insertion pieces  15 , each of the insertion pieces  15  is temporarily directed downward and outward by elasticity as shown in  FIG. 1B ′. 
     As shown in  FIG. 1C , a plurality of insertion holes  21  is formed on an upper edge of a side surface of the outsole portion  3  at an entire outer periphery of the outsole portion  3  so that the insertion pieces  15  are inserted into and penetrated through (completely inserted into) the insertion holes  21 . The insertion holes  21  are located at a position of each of the insertion pieces  15  in a state that the upper portion  5  is attached. An inlet  23  is open at a surface of the insertion holes  21 . 
     In order to ensure durability against the force applied from the insertion pieces  15  of the upper portion  5  to a peripheral part of the insertion holes of the outsole portion  3 , the insertion holes  21  are preferably as small as possible. Accordingly, as shown in FIGS.  3 AF 1  to  3 AF 4  and other figures, a lateral dimension (vertical direction in the figures) of each of the insertion holes  21  is specified so that the insertion pieces  15  can be inserted into the insertion holes  21  after when the insertion pieces  15  become smaller in width by being contacted with the insertion holes  21  and pushed by the insertion holes  21  from both lateral ends of the insertion pieces  15  to shrink (reduce a diameter of) the locking hole  19 . The upper portion is directly attached to the bottom of the recess located at the center of the outsole portion by locking the locking hole with the locking protrusions of the outsole portion. However, the insertion pieces of the upper portion are inserted into and penetrated through the insertion holes of the outsole portion. Thus, the upper portion is indirectly attached to a peripheral part of the outsole portion. Accordingly, the force applied to the upper portion is concentrated on the inlet of the insertion holes of the outsole portion. Because of this, the insertion holes are specified to be as small as possible, and a volume of the peripheral part to support the insertion holes is specified to be as large as possible to ensure durability against the force applied from the upper portion to the peripheral part of the inlet of the insertion holes of the outsole portion. 
     As shown in  FIG. 1C ,  FIG. 2C  and other figures, an outlet  29  of each of the insertion pieces  15  is open to an inner peripheral wall  27  of a recess  25  formed on the center of the upper surface of the outsole portion  3 . Locking protrusions  31  are formed at a bottom of the recess  25  of the outsole portion  3  at a portion near the outlet  29 . The locking protrusions  31  are arranged on a plurality of the bottom of the recess  25  at a position enabling to lock the locking hole  19  of each of the insertion pieces  15  in a state that the upper portion  5  is attached. Each of the locking protrusions  31  is formed in an approximately short cylindrical shape. Each of the locking protrusions  31  is inclined upward in a slope shape toward a front side in a direction of inserting the insertion pieces  15  so as not to prevent the insertion of the insertion pieces  15 . On the other hand, a tip of each of the locking protrusions  31  is projected toward the insertion direction so that the insertion pieces  15  are not easily detached (FIGS.  3 D 1  to  3 D 4 ). 
     From the above, the direction of inserting the insertion pieces  15  into the insertion holes  21  is directed from an outer periphery of the outsole portion  3  to an inner side, different from the conventional one which is directed in a vertical direction. Each of the insertion pieces  15  is sharp-edged at a front end and tongue-shaped so that each of the insertion pieces  15  can be easily inserted into the narrow insertion holes  21  ( FIGS. 1B, 1B ′,  FIG. 2B , FIGS.  3 F 1  to  3 F 4 ). Each of the locking holes  19  is formed in a long shape longitudinally along a direction of inserting the insertion pieces  15  and is sharp-edged at a rear end so that the insertion pieces can be easily inserted into the insertion holes and easily pulled out of the insertion holes ( FIGS. 1B, 1B ′,  FIG. 2B ). Each of the locking holes  19  is a so-called tear shape. 
     After the insertion pieces  15  are penetrated through the outlet  29  of the recess  25 , the locking hole  19 , which is temporarily deformed to be smaller in width in the insertion holes  21 , is expanded by elasticity or a finger of a user. Then, the insertion pieces  15  are further expanded in the insertion direction, and the locking hole  19 , which is enlarged in diameter, is fitted to the locking protrusions  31  from the tip of the locking protrusions  31 , the tip being projected toward the insertion direction. Thus, the locking hole  19  formed on each of the insertion pieces  15  is locked. When the force is applied in a direction of pulling the insertion pieces  15  out of the insertion holes  21 , the insertion pieces  15  are in contact with the insertion holes  21  again and pushed from both lateral ends. Thus, the force is applied in the direction of shrinking the locking hole  19 . Because of this, the locking hole  19  strongly holds the locking protrusions  31 , friction becomes larger, and the fitting becomes more tightly. Consequently, there is less possibility that the insertion pieces  15  are pulled out of the insertion holes  21 . The insertion pieces  15  are restricted from being moved freely by the insertion holes  21 . Even when one of the insertion pieces  15  is unlocked, the insertion pieces are not pulled out of the insertion holes unless neighboring insertion pieces are pulled out together. Namely, the attachment between the upper portion and the outsole portion is not released in the configuration of the present invention. Thus, the upper portion  5  is sufficiently prevented from pulling out of the outsole portion. Accordingly, safety of the footwear is considered enough, although an entire weight of a user is applied the footwear. 
     As the area to insert and lock the insertion pieces  15  becomes larger, the connecting area between the upper portion  5  and the outsole portion  3  can be larger and the upper portion  5  can be attached strongly to the outsole portion  3 . Since the insertion pieces  15  are directed toward an inner side, not downward, the space is largely kept in an approximately horizontal direction. Thus, an area in a lateral dimension of the outsole portion can be smaller, and the footwear can be thinner. 
     As show in  FIGS. 1B, 1B ′,  FIGS. 2B, 2D ′ and other figures, a portion connecting each of the insertion pieces  15  of the upper portion  5  is formed in a smooth curved line  33 , and fitted into a groove  34  formed between each of the insertion holes of the outsole portion  3 . Furthermore, each of the locking holes  19  is locked on the locking protrusions  31 , and therefore both ends of the curved line  33  are pulled by the insertion pieces  15 . Although the insertion pieces  15  are not formed on the curved line  33 , the force in the center direction of the outsole portion  3  is also applied to the curved line  33 . Thus, the upper portion  5  is more strongly attached to the outsole portion  3 . 
     The detachable mechanism  7  formed by the insertion pieces  15  and the locking protrusions  31  is formed on the recess  25 . As shown in  FIG. 1E ,  FIG. 2E  and  FIG. 4E , the recess  25  is covered with the insole portion  9 . A lower surface of the insole portion  9  has a shape to fill a gap of the locking protrusions  31 . Accordingly, when the insole portion  9  is attached, there is less possibility that the locking hole  19  is removed from the locking protrusions  31 . 
     By the above described configurations, the upper portion  5  can be replaced freely. If a wide variety of upper portions are prepared, the outsole portion  3  can be efficiently re-used and the footwear can be changed to have different functions. Consequently, a user can enjoy various fashions and can follow a trend while preventing the footwear from becoming old-fashioned. If the outsole portion  3 , the upper portion  5  and the insole portion  9  are formed from the same reusable material, each portion can be recycled and the resource can be economically re-used. 
       FIGS. 5A to 5E and 5A ′ to  5 E′ show a footwear of the fifth embodiment of the present invention. 
     The footwear  1  of the fifth embodiment is a sandal. An upper portion  5  is detachably attached to an outsole portion  3  and covered with an insole portion  9 . Thus, the upper portion  5  can be replaced. 
     As shown in  FIGS. 5C and 5C ′, the outsole portion  3  forms a lower part of the footwear  1 , and the outsole portion  3  has a portion  11  to be in contact with the ground. 
     As shown in  FIGS. 5B and 5B ′, the upper portion  5  can be attached to and detached from the outsole portion  3 , and the upper portion  5  has a portion  13  crossing over instep of foot. For attaching and detaching the upper portion  5 , a plurality of insertion pieces  15  is formed on an entire periphery of the upper portion  5 . 
     The insertion pieces  15  are integrally formed with the upper portion  5  by the same material having strength and elasticity. For example, synthetic resin is used. The insertion pieces  15  are formed on a periphery of the upper portion  5  and aligned along a frame portion  17 . The insertion pieces  15  are arranged approximately horizontally toward an inner side of the upper portion  5 . 
     A plurality of insertion holes  21  is formed on the outsole portion  3  at a position of each of the insertion pieces  15  in a state that the upper portion  5  is attached so that the insertion pieces  15  are inserted into and penetrated through (completely inserted into) the insertion holes  21 . The insertion holes  21  are formed on an upper edge of a side surface of the outsole portion  3  at an entire outer periphery of the outsole portion  3 . An inlet  23  is open at a surface of the insertion holes  21 . 
     A recess  25  having a shallow depth is formed on the center of the upper surface of the outsole portion  3 . The recess  25  has a shape and an area to be completely covered by the insole portion  9  when the insole portion  9  is fitted with the recess  25 . As shown in  FIGS. 5C, 5C ′ and other figures, an outlet  29  of each of the insertion holes  21  is open to an inner peripheral wall  27  of the recess  25 . Because of this, the direction of inserting the insertion pieces  15  into the insertion holes  21  is directed from an outer periphery of the upper portion  5  to an inner side. 
     A locking hole  19  is formed at an approximately center of a tip of each of the insertion pieces  15 . The locking hole  19  is formed in a long shape longitudinally along a direction of inserting the insertion pieces  15  and is sharp-edged at a rear end. The locking hole  19  is a so-called tear shape. A lateral dimension of each of the insertion holes  21  is specified so that the insertion pieces  15  can be inserted into the insertion holes  21  after when the insertion pieces  15  become smaller in width by being contacted with the insertion holes  21  and pushed by the insertion holes  21  from both lateral ends of the insertion pieces  15  to shrink the locking hole  19 . 
     The configurations described above are same as the first embodiment. In the fifth embodiment, other than the configurations above, a fitting hole  37  is formed at a bottom of the recess  25  at a position to be overlapped with the locking hole  19  in a state that the upper portion  5  is attached to the outsole portion  3 . Furthermore, fitting protrusions  39  are formed on the insole portion  9  at a position enabling to pass through the locking holes  19  and to fit with the fitting holes  37 . 
     Namely, after the insertion pieces  15  are inserted into the insertion holes  21 , the fitting protrusions  39  formed on the insole portion  9  are inserted into the locking holes  19  and fitted with the fitting holes  37 . Thus, the locking holes  19  are attached to the outsole portion  3  via the fitting protrusions  39 . Since a locking shape is formed on a tip of the fitting protrusions  39 , the fitting protrusions  39  are tightly attached to the outsole portion  3  and hardly removed from the locking hole  19 . In other words, the insertion pieces  15  is hardly pulled out from the insertion holes  21 , and the upper portion  5  is sufficiently prevented from being pulled out. 
     Functions and effects of the fifth embodiment are same as the first embodiment except for the method of attaching the insertion pieces. 
       FIGS. 6A to 6E, 6A ′ to  6 E′ and  6 E″ show a footwear of the sixth embodiment of the present invention. The explanations of the configurations in common with the first embodiment are omitted since the configurations are written in the paragraph [0040]. Refer to the paragraph [0040] for the names and the explanations of the common configurations. 
     In the sixth embodiment, different from other embodiments, after the insertion pieces  15  are inserted into the insertion holes  21  and reached to the recess  25  formed at the center, locking claws  41  are locked by lock receiving portions  45  arranged at the bottom of the recess  25 . A shape of the lock receiving portions  45  is inclined upward in a slope shape toward a front side in the insertion direction. Because of this, the lock receiving portions  45  do not interfere with the insertion of the insertion pieces  15 , and the insertion pieces  15  can be smoothly attached and detached. A fit-in port of the lock receiving portions  45  is narrower than a dimension of the corresponding part of the locking claws  41  and a tip of the lock receiving portions  45  is projected ( FIG. 6E ″) toward the insertion direction. Because of this, the locking claws  41  are prevented from being removed from the lock receiving portions  45 . 
     Accordingly, same as the first embodiment, the insertion pieces are hardly pulled out of the insertion holes by the above described locking mechanism. Thus, the upper portion can be sufficiently prevented from being pulled out and the footwear can be thinner. Namely, functions and effects of the sixth embodiment are same as the first embodiment except for the method of attaching the insertion pieces. 
       FIGS. 7A to 7E, 7A ′ to  7 E′ and  7 E″ show a footwear of the seventh embodiment. The explanations of the configurations in common with the first embodiment are omitted since the configurations are written in the paragraph [0040]. Refer to the paragraph 
     for the names and the explanations of the common configurations. 
     In the seventh embodiment, different from other embodiments, after the insertion pieces  15  are inserted into the insertion holes  21  and reached to the recess  25  located at the center, locking constrictions  43  are locked by being fitted with the lock receiving portions  45  formed at the bottom of the recess  25 . The lock receiving portions  45  and the tip of the insertion pieces  15  have protrusions and recesses corresponding to each other. A shape of the lock receiving portions  45  is inclined upward ( FIG. 7E ″) in a slope shape toward a front side in the insertion direction. Because of this, the lock receiving portions  45  do not interfere with the insertion of the insertion pieces  15 , and the insertion pieces  15  can be smoothly attached and detached. A fit-in port of the lock receiving portions  45  is narrower than a dimension of the corresponding part of the locking claws  41 . Because of this, the locking constrictions  43  are prevented from being removed from the lock receiving portions  45 . 
     Accordingly, same as the first embodiment, the insertion pieces  15  are hardly pulled out of the insertion holes  21  by the above described locking mechanism. Thus, the upper portion  5  can be sufficiently prevented from being pulled out and the footwear can be thinner. 
     Namely, functions and effects of the seventh embodiment are same as the first embodiment except for the method of attaching the insertion pieces. 
       FIGS. 9H, 9H ′ and  9 E′ show partial cross-sectional views of the insertion pieces of the footwear of the ninth embodiment. 
     Functions, effects and configurations of the footwear of the present embodiment are same as the first embodiment except for the method of locking the insertion pieces  15  on the outsole portion  3 . The explanations are omitted except for the different part. 
     In the present embodiment, the lock receiving portions  45  are formed on the insole portion  9 . The lock receiving portions  45  and the tip of the insertion pieces  15  have protrusions and recesses corresponding to each other. When the insole portion  9  is attached to the outsole portion  3 , the locking claws  41  formed on each of the insertion pieces  15  are locked on the lock receiving portions  45 . In this case, since the insertion pieces  15  are locked by attaching the insole portion  9 , the insole portion  9  should be strongly attached to the outsole portion  3 . A locking shape  47  having protrusions and recesses is formed on the outsole portion  3  and the insole portion  9  at a portion between each of the neighboring insertion pieces  15  so as to attach the insole portion  9  strongly. 
     From the above, same as the first embodiment, the insertion pieces are hardly pulled out of the insertion holes. Thus, the upper portion  5  can be sufficiently prevented from being pulled out and the footwear can be thinner. 
       FIGS. 9I, 9I ′ and  9 E″ show a partial cross-sectional view of the insertion pieces of the footwear of the tenth embodiment. 
     Functions, effects and configurations of the footwear of the present embodiment are same as the first embodiment except for the method of locking the insertion pieces  15  on the outsole portion  3 . The explanations are omitted except for the different part. 
     In the present embodiment, the lock receiving portions  45  are formed by attaching the insole portion  9  on the outsole portion  3 . The lock receiving portions  45  and the tip of the insertion pieces  15  have protrusions and recesses corresponding to each other. When the insole portion  9  is attached to the outsole portion  3 , the locking claws  41  formed on each of the insertion pieces  15  are locked on the lock receiving portions  45  formed by both the insole portion  9  and the outsole portion  3 . In this case, since the insertion pieces  15  are locked by attaching the insole portion  9 , the insole portion  9  should be strongly attached to the outsole portion  3 . A locking shape  47  having protrusions and recesses is formed on the outsole portion  3  and the insole portion  9  at a portion between each of the neighboring insertion pieces  15  so as to attach the insole portion  9  strongly. 
     From the above, same as the first embodiment, the insertion pieces are hardly pulled out of the insertion holes. Thus, the upper portion can be sufficiently prevented from being pulled out and the footwear can be thinner. 
       FIGS. 10A to 10E, 10D ′,  10 E′ and  10 F 1  to  10 F 3  show a footwear of the eleventh embodiment. The names and the explanations are same as the paragraph [0040] except that B′ and C′ are not provided on the figures. 
     In the eleventh embodiment, different from other embodiments, a mechanism of attaching the insertion pieces  15  to the outsole portion  3  is not formed. For example, the mechanism is the fitting protrusions  31  in the first embodiment. In the present embodiment, as shown the insertion process in FIGS.  10 F 1 ,  10 F 2  and  10 F 3 , the insertion holes  21  themselves function as the lock receiving portion. The locking claws  41  formed on each of the insertion pieces  15  are locked at the same time when the insertion pieces  15  are inserted into the recess  25 . Accordingly, same as the first second embodiment, the insertion pieces are hardly pulled out of the insertion holes by the above described locking mechanism. Thus, the upper portion can be sufficiently prevented from being pulled out and the footwear can be thinner. Namely, functions and effects are same as the first embodiment except for the method of attaching the insertion pieces. 
     Other Embodiments 
     (1) In the perspective view of the above described embodiments, the inlets  23  of the insertion holes  21  are open to a side surface of the periphery of the outsole portion  3  and the insertion holes  21  are approximately horizontal entirely from the inlet to the outlet. As shown in FIGS.  4 D 1   a ,  4 D 1   b ,  4 D 1   c  and  4 D 1   e  as the second embodiment, the inlets  23  can be open to an upper surface of the periphery of the outsole portion  3  and the insertion holes  21  can be formed in a combination of an approximately L-shape and an approximately horizontal shape. 
     (2) As shown in FIGS.  4 D 2   a ,  4 D 2   b ,  4 D 2   c  and  4 D 2   e  as the third embodiment, the inlet  23  can be open to a periphery of a corner portion crossing the side surface and the upper surface, and the insertion holes  21  can be formed in a combination of an approximately L-shape and an approximately horizontal shape. 
     (3) In the above described embodiments, the insole portion  9  should be removed when attaching and detaching the upper portion  5  to expose the detachable mechanism  7 . However, in another embodiment, the detachable mechanism  7  is always exposed from the bottom surface (reverse side of the upper surface) of the outsole portion  3  and the locking protrusions  31  are directed in the opposite direction (downward). The operations of the insertion or the locking can be done form the bottom surface (reverse side) of the outsole portion  3 . Accordingly, the upper portion  5  can be attached and detached without removing the insole portion  9 . 
     (4) In addition to change the direction of the locking protrusions  31  downward as described in (3), the detachable mechanism  7  exposed on the bottom surface (reverse side) of the outsole portion  3  can be covered with a back lid  35 . When attaching or detaching the upper portion  5 , the back lid  35  is removed to expose the detachable mechanism  7 . In order to prevent the back lid  35  from falling downward, the back lid  35  and the bottom surface (reverse side) of the outsole portion  3  are locked by the locking shape  47  having protrusions and recesses. 
     (5) In the above described case, as shown in FIGS.  4 D 3   a ,  4 D 3   b ,  4 D 3   c  and  4 D 3   e  as the fourth embodiment, the upper portion  5  can be formed integrally with the insole portion  9 . When the insole portion  9  is integrally formed and not detachable from the upper portion  5 , waterproofing performance is improved. Also in this case, in order to prevent the back lid  35  from falling downward, the back lid  35  and the bottom surface (reverse side) of the outsole portion  3  are locked by the locking shape  47  having protrusions and recesses. 
     (6) In the above described embodiments, the locking hole  19  is sharp-edged at a rear end. In another embodiment, the locking hole  19  can be sharp-edged at a front end. In addition, both the front end and the rear end can be sharp-edged. Because of this, the insertion pieces  15  can be more easily inserted. 
     (7) As shown in  FIG. 6D ′,  FIG. 7D ′,  FIGS. 9G, 9G ′,  9 G″ and  FIG. 10D ′, protrusions having a locking shape can be formed on gap parts to prevent the insole portion  9  from removing, in addition to the protrusions to prevent the back lid  35  from falling. Furthermore, the insole portion  9  can be locked by forming the locking shape  47  having protrusions and recesses corresponding to the recess  25  of the outsole portion on the insole portion  9  or whole the back lid  35 . 
     (8) In the above described embodiments, each of the lock receiving portions  45  is integrally formed connecting the edges of neighboring locking claws  41  or neighboring locking constrictions  43 . However, the lock receiving portions  45  can be formed by two protrusions. Also in such a case, if the protrusions are inclined upward in a slope shape toward a front side in the insertion direction, the protrusions do not interfere with the insertion of the insertion pieces  15  and the insertion pieces  15  can be smoothly attached and detached. If the fit-in port of the lock receiving portions  45  is narrower than a dimension of the corresponding part of the locking claws  41  or the locking constrictions  43 , or if the tip of the lock receiving portions  45  is projected toward the insertion direction, the locking claws  41  or the locking constrictions  43  are prevented from being removed from the lock receiving portions  45 . 
     (9) In the above described embodiments, the tip of the insertion pieces is shown as an arrow shape in case of the locking claws, and as a circular shape in case of the locking constrictions. However, the shape can be any shape as long as the lock receiving portions  45  have a shape capable of locking and the lock receiving portions  45  has a protrusion such as a claw or a constriction. For example, a particular shape such as a star-shape and a heart-shape or an asymmetry shape can be used for locking. 
     (10) In the locking claws  41  or the locking constrictions  43  of the above described embodiments, the claw or the constriction is formed in left and right directions of the insertion piece. However, the claw or the constriction can be formed only in one of the left and right directions, both upper and lower direction, one of the upper and lower direction, or all directions. 
     Also in such a case, if the protrusions are inclined upward in a slope shape toward a front side in the insertion direction, the protrusions do not interfere with the insertion of the insertion pieces and the insertion pieces can be smoothly attached and detached. If the fit-in port of the lock receiving portions  45  is narrower than a dimension of the corresponding part of the locking claws  41  or the locking constrictions  43 , or if the tip of the lock receiving portions  45  is projected toward the insertion direction, the locking claws  41  or the locking constrictions  43  are prevented from being removed from the lock receiving portions  45 . 
     (11) As for the locking claws  41  or the locking constrictions  43 , in addition to the above described mechanism of preventing them from being removed from the lock receiving portions  45 , a protrusions for hooking a finger can be formed on the insertion pieces  15  or a recess for inserting a finger can be formed on the neighboring part of the lock receiving portions  45  having a recessed shape as shown in  FIG. 7C  so that the locking claws  41  or the locking constrictions  43  can be removed easily. 
     (12) As for the lock receiving portions  45 , as shown in the plan views shown in FIGS.  8 F 1  to  8 F 4  and the cross-sectional views shown in FIGS.  8 D 1  to  8 D 4 , the insertion pieces  15  can be inserted into the lock receiving portions  45  formed in a loop shape after the insertion pieces  15  are penetrated through the recess  25  to lock the insertion pieces  15 , same as the locking claws  41  of the tenth embodiment. 
     (13) In the above described embodiments, as for the upper portion  5  and the outsole portion  3 , the insertion pieces  15  and the insertion holes  21  are formed on an entire periphery. However, when the footwear (e.g. sandal) has a shape crossing over foot only at a particular portion and the upper portion is replaced only at the particular portion, the insertion pieces  15  and the insertion holes  21  can be formed only at the particular portion. 
     (14) The footwear  1  of the above described embodiments is a sandal. As another embodiment, the present invention can be applied to other kinds of footwear  1 , such as shoes or boots, formed by the outsole portion  3  and the upper portion  5 . 
     (15) In the above described embodiments, the insertion pieces  15  are made of the same material with the upper portion  5  and integrally formed with the upper portion  5 . In another embodiment, the insertion pieces  15  can be made of a different material, of course. For example, the insertion pieces  15  can be made of synthetic resin, while the upper portion  5  is made of leather. In addition, the insertion pieces  15  and the upper portion  5  can be integrated by connecting with each other. 
     Note that, this invention is not limited to the above-mentioned embodiments. Although it is to those skilled in the art, the following are disclosed as the one embodiment of this invention.
         Mutually substitutable members, configurations, etc. disclosed in the embodiment can be used with their combination altered appropriately.   Although not disclosed in the embodiment, members, configurations, etc. that belong to the known technology and can be substituted with the members, the configurations, etc. disclosed in the embodiment can be appropriately substituted or are used by altering their combination.   Although not disclosed in the embodiment, members, configurations, etc. that those skilled in the art can consider as substitutions of the members, the configurations, etc. disclosed in the embodiment are substituted with the above mentioned appropriately or are used by altering its combination.       

     While the invention has been particularly shown and described with respect to preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the sprit and scope of the invention as defined in the appended claims.