Patent Publication Number: US-2022225736-A1

Title: Shoe

Description:
TECHNICAL FIELD 
     The present invention relates to a shoe. 
     BACKGROUND ART 
     Shoes with uppers that can be easily tightened are known. For example, Patent Literature 1 describes a shoe that includes a shoelace for tightening the upper, and a fastener provided midway along the shoelace. The shoelace passes, in a zigzag pattern, through eyelets formed on the both side parts of the upper between which an opening is provided, and an end of the shoelace is fixed to the upper. The fastener is fixed around the wearing opening on the top of the upper. 
     PRIOR ART REFERENCE 
     Patent Literature 
     Patent Literature 1: Specification of U.S. Pat. No. 9,730,492 
     Patent Literature 2: Specification of U.S. Pat. No. 5,353,483 
     Patent Literature 3: Japanese Unexamined Patent Application Publication No. 10-179210 
     Patent Literature 4: Japanese Translation of PCT International Application Publication No. 2018-532554 
     Patent Literature 5: Japanese Patent No. 6236142 
     Patent Literature 6: Japanese Patent No. 6117380 
     SUMMARY OF INVENTION 
     Technical Problem 
     With regard to the upper tightening mechanism and the fit of the shoe, the inventors have found the following recognition. 
     To reduce the time for putting on and off a shoe, it is desirable that the upper can be easily tightened. However, with the shoe described in Patent Literature 1, since the fastener is fixed around the wearing opening on the top of the upper, the tightening force is concentrated around the wearing opening. Accordingly, the tightening force decreases from the wearing opening toward the toe, and the space between the upper and the instep becomes larger, which impairs the fit. 
     To improve the fit on the toe side, strongly tightening the entire shoelace may be considered. However, in this case, the tightening force around the wearing opening will become excessively large, which is disadvantageous in terms of the comfort. Therefore, the inventors have found that there is room for improvement in the shoe described in Patent Literature 1, in terms of enabling both the easy tightening of the upper and the maintaining of the fit. 
     The present invention has been made in view of such an issue, and a purpose thereof is to provide a shoe of which the upper can be easily tightened and of which the fit can be maintained. 
     Solution to Problem 
     In response to the above issue, a shoe according to an embodiment of the present invention includes a sole, an upper provided above the sole to accommodate a foot, a tightening part that applies tightening force to the upper, and a force transmitter that transmits tightening force from the tightening part to a lower part of a midfoot portion of the upper. 
     Optional combinations of the above, and implementation of the present invention, including the constituting elements and expressions, in the form of methods, apparatuses, programs, transitory or non-transitory storage medium storing programs, or systems may also be practiced as additional modes of the present invention. 
     Advantageous Effects of Invention 
     The present invention provides a shoe of which the upper can be easily tightened and of which the fit can be maintained. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view that schematically illustrates a shoe according to an embodiment of the present invention; 
         FIG. 2  is a front view of the shoe shown in  FIG. 1 ; 
         FIG. 3  is a side view of the shoe shown in  FIG. 1 ; 
         FIG. 4  is a plan view that illustrates the vicinity of a tightening part of the shoe shown in  FIG. 1 ; 
         FIG. 5  is a plan view that illustrates positional relationships among a shoelace of the shoe shown in  FIG. 1 , and the thenar eminence and the hypothenar eminence of a wearer; 
         FIG. 6  is a plan view that schematically illustrates a shoe according to a first modification; 
         FIG. 7  is a side view of the shoe shown in  FIG. 6 ; and 
         FIG. 8  is a side view that schematically illustrates a shoe according to a second modification. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following, the present invention will be described based on a preferred embodiment with reference to each drawing. In the embodiment and modifications, like reference characters denote like or corresponding constituting elements and members, and the same description will be omitted as appropriate. Also, the dimensions of a member may be appropriately enlarged or reduced in each drawing in order to facilitate understanding. Further, in each drawing, part of a member less important in describing the embodiment may be omitted. 
     Also, terms including ordinal numbers, such as “first” and “second”, are used to describe various constituting elements; however, such terms are used in order to distinguish one constituting element from another and do not limit the constituting elements. 
     [Embodiment] 
     In the following, a configuration of a shoe  100  according to an embodiment of the present invention will be described with reference to the drawings.  FIG. 1  is a plan view that schematically illustrates the shoe  100  according to the embodiment. Each drawing mentioned below, including  FIG. 1 , illustrates a shoe for a right foot, unless otherwise specified. However, the description in the present specification is also applicable to a shoe for a left foot.  FIG. 2  is a front view of the shoe  100 .  FIG. 3  is a side view of the shoe  100 .  FIG. 3  shows the shoe  100  viewed from the lateral side of the foot. 
     The shoe  100  of the present embodiment can be used for walking shoes, running shoes, safety shoes, and sports shoes for tennis or basketball, for example, and the use of the shoe  100  is not limited. The shoe  100  includes a sole  10  and an upper  20 . As illustrated in  FIG. 1 , a portion on the medial side (the left side in  FIG. 1 ) with respect to a center line La in a width direction of the upper  20  will be referred to as a medial portion  22 , and a portion on the lateral side (the right side in  FIG. 1 ) with respect to the center line La in a width direction of the upper  20  will be referred to as a lateral portion  24 . Also, the direction from the lateral side toward the medial side of the foot will be referred to as the inner side, and the opposite direction will be referred to as the outer side. Further, a direction along the center line La will be referred to as a “longitudinal direction”. 
     Also, the direction toward the toe side along the center line La will be referred to as the “front side” or “front”, and the opposite direction will be referred to as the “rear side” or “rear”. Accordingly, a width direction is perpendicular to the center line La. Also, in the upper  20 , a portion corresponding to the metatarsal bones (see also  FIG. 5 ) in a longitudinal direction will be referred to as a midfoot portion  20   m.  When the longitudinal length of the shoe  100  is regarded as 100%, the midfoot portion  20   m  corresponds to a region from 25% to 85% or, more exactly, from 30% to 80%, from the tip, in a range parallel with a straight line perpendicular to the center line La. Also, in the upper  20 , a portion in front of the midfoot portion  20   m  in a longitudinal direction will be referred to as a forefoot portion  20   f,  and a portion in the rear of the midfoot portion  20   m  in a longitudinal direction will be referred to as a rearfoot portion  20   g.  The forefoot portion  20   f  is a portion that almost corresponds to the phalanges, and the rearfoot portion  20   g  is a portion that almost corresponds to the tarsals. 
     In the state where the shoe  100  is placed on a horizontal plane (hereinafter, referred to as a “horizontal state”), the upper side will be referred to as the “upper side” or “above”, and the opposite side will be referred to as the “lower side” or “below”. Also, in a horizontal state, a direction extending vertically will be referred to as a “vertical direction”. 
     (Sole) 
     The sole  10  is a portion to be in contact with the ground. The sole  10  includes an outsole  12  and an insole  14 . Above the sole  10 , the upper  20  is fixed by means of bonding or the like. The sole  10  may include a midsole between the outsole  12  and the insole  14 . The sole  10  may have a unisole structure and need not necessarily include the insole  14 . 
     (Upper) 
     The upper  20  is provided above the sole  10  to accommodate a foot. The upper  20  surrounds an internal space  20   a  for accommodating a foot. On the upper  20 , a central opening  20   c  is formed from a wearing opening  20   b  toward the front. The central opening  20   c  is not an essential configuration, and the upper  20  may have a so-called monosock structure. The upper  20  includes the medial portion  22 , the lateral portion  24 , an eyelet formation part  26 , and eyelet parts  28 . Also, on the upper  20 , a tightening part  30  for applying tightening force to the upper  20  is provided, and a force transmitter  18  for transmitting the tightening force from the tightening part  30  to a lower part of the midfoot portion  20   m  of the upper  20  is also provided. In the present embodiment, the force transmitter  18  includes a clasp  36  for detachably fixing the tightening part  30  to the upper  20 , and a receiving part  38 . Also, on the upper  20 , a position adjustment mechanism  42  and a shoe tongue  70  are provided.  FIG. 1  shows a state where the clasp  36  is not fixed to the upper  20 , and each of  FIGS. 2 and 3  shows a state where the clasp  36  is fixed to the upper  20 . 
     (Tightening Part) 
     The tightening part  30  tightens the upper  20 . The tightening part  30  in this example is disposed to across the central opening  20   c  in a width direction. The tightening part  30  applies, to the upper  20 , tightening force for closing the central opening  20   c  in the width directions. The tightening part  30  may include a belt-shaped member, a string-shaped member, or the both. The tightening part  30  in the present embodiment is a shoelace  30   s,  which includes a first portion  32  and a second portion  34  formed continuously. The first portion  32  corresponds to a portion from a boundary  30   b  between the first portion  32  and the second portion  34  to an end  32   e  of the shoelace  30   s.  The second portion  34  corresponds to a portion from the boundary  30   b  between the first portion  32  and the second portion  34  to an end  34   e  of the shoelace  30   s.  The boundary  30   b  and the ends  32   e  and  34   e  will be described later. 
     Through each eyelet part  28 , the first portion  32  or the second portion  34  passes, so as to transmit the tightening force from the tightening part  30  to the upper  20 . The eyelet parts  28  in this example are grommets that each have a hole vertically piercing. The eyelet parts  28  are formed in the eyelet formation part  26  provided along a circumferential edge of the central opening  20   c  of the upper  20 . The eyelet formation part  26  includes a first formation part  26   a  provided in the medial portion  22 , and a second formation part  26   b  provided in the lateral portion  24 . To obtain higher rigidity than the surrounding portions, the eyelet formation part  26  may be formed of a material having lower elasticity or flexibility than the surrounding portions, a material thicker than the surrounding portions, a material denser than the surrounding portions, or a material harder than the surrounding portions. Also, the eyelet formation part  26  may be formed of the same material as the surrounding portions. 
     The eyelet parts  28  in the present embodiment include outer eyelet parts  28   e  provided on the lateral side, and inner eyelet parts  28   j  provided on the medial side. Multiple inner eyelet parts  28   j  are provided in the first formation part  26   a,  and multiple outer eyelet parts  28   e  are provided in the second formation part  26   b.  To even the tightening force distribution in a longitudinal direction, the number of inner eyelet parts  28   j  (five, for example) is larger than the number of outer eyelet parts  28   e  (four, for example). Also, the number of inner eyelet parts  28   j  is odd, and the number of outer eyelet parts  28   e  is even, so that the sum of them becomes an odd number. Accordingly, the outer eyelet parts  28   e  and the inner eyelet parts  28   j  are arranged to be asymmetric in a width direction. 
     (Clasp) 
     The clasp  36  is a member for detachably fixing the tightening part  30  to the lower part of the midfoot portion  20   m  of the upper  20  and corresponds to the force transmitter. The clasp  36  is connected to the receiving part  38  provided on the upper  20  so as to be fixed to the upper  20 . Accordingly, the clasp  36  is placed in a fixed state of being connected to the receiving part  38 , and an unfixed state of being separated from the receiving part  38 . When the clasp  36  is fixed, it is preferable that the clasp  36  is fixed around a boundary part  20   h  between the upper  20  and the sole  10 , on the lateral side of the midfoot portion  20   m.  However, the receiving part  38  has only to be fixed onto a line that constitutes the contour of the upper  20  in top view or to a position below the line. Alternatively, the receiving part  38  may be fixed to a side surface of the sole  10 . The contour of the upper  20  is a line obtained by connecting outermost projecting parts in the upper  20 . The clasp  36  has only to be capable of fixing the tightening part  30  and may be a hook-and-loop fastener, a hook, a magnet, or the like. In this example, the clasp  36  is a male part of a resin buckle, and the receiving part  38  is a female part of the buckle. The clasp  36  and the receiving part  38  may also be a front release buckle or a side release buckle. 
     (Position Adjustment Mechanism) 
     Since the shape of a foot is different for each wearer, the fixed position of the clasp  36  may desirably be adjustable. Accordingly, the position adjustment mechanism  42  is provided in the present embodiment with which the fixed position of the clasp  36  on the upper  20  can be shifted in the longitudinal directions. For example, the position adjustment mechanism  42  may be a slider mechanism. The position adjustment mechanism  42  in the present embodiment includes a rail member  42   b  provided on the lateral portion  24  of the upper  20  such as to extend in a longitudinal direction, and a slider  42   s  provided to be longitudinally movable along the rail member  42   b.  To the slider  42   s,  the receiving part  38  is fixed. The position adjustment mechanism is not essential, and the position of the receiving part  38  may also be fixed. 
     The shoe tongue  70  covers the central opening  20   c  from the internal space  20   a  side of the upper  20 . As the shoe tongue  70 , a so-called split tongue may be adopted in which the ends in a width direction thereof are fixed respectively at the left and right ends of the central opening  20   c,  and a middle portion of the shoe tongue  70  is split into left and right parts. 
       FIG. 4  is also referred to.  FIG. 4  is a plan view that illustrates the vicinity of the tightening part  30 .  FIG. 4  illustrates the clasp  36  partially cut out. The multiple inner eyelet parts  28   j  will be respectively referred to as eyelet parts  28   j   1 ,  28   j   2 ,  28   j   3 ,  28   j   4 , and  28   j   5  serially from the front toward the rear. Also, the multiple outer eyelet parts  28   e  will be respectively referred to as eyelet parts  28   e   1 ,  28   e   2 ,  28   e   3 , and  28   e   4  serially from the front toward the rear. The eyelet parts  28   j   1 ,  28   j   2 ,  28   j   3 ,  28   j   4 , and  28   j   5  may be evenly spaced or may be partially spaced unevenly. Also, the eyelet parts  28   e   1 ,  28   e   2 ,  28   e   3 , and  28   e   4  may be evenly spaced or may be partially spaced unevenly. 
     The eyelet part  28   j   3 , which is disposed in the middle in a longitudinal direction among the inner eyelet parts  28   j,  will be particularly referred to as a middle eyelet part  28   j   3 . In the tightening part  30 , a part laid through the middle eyelet part  28   j   3  is defined as the boundary  30   b  between the first portion  32  and the second portion  34 . Also, in the tightening part  30 , a portion extending from the middle eyelet part  28   j   3  toward the rear side is defined as the first portion  32 . Also, in the tightening part  30 , a portion extending from the middle eyelet part  28   j   3  toward the front side is defined as the second portion  34 . Accordingly, the first portion  32  and the second portion  34  have a relationship such that, when one of them becomes longer, the other becomes shorter. Therefore, the position of the boundary  30   b  in the entire length of the tightening part  30  changes accordingly. 
     The end  32   e  of the first portion  32  and the end  34   e  of the second portion  34  are fixed to the lateral side of the upper  20 . In this example, the end  32   e  of the first portion  32  is fixed at the eyelet part  28   e   2 , which is the second outer eyelet part  28   e  from the front. Also, the end  34   e  of the second portion  34  is fixed at the eyelet part  28   e   4 , which is the fourth outer eyelet part  28   e  from the front (or the rearmost outer eyelet part  28   e ). An end being fixed as used herein means that, even when the clasp  36  is pulled, the end is retained without coming out of the corresponding eyelet part. The fixing structure for the ends  32   e  and  34   e  is not particularly limited. In this example, at each of the ends  32   e  and  34   e,  a knot (node) that is large enough not to pass through the corresponding eyelet part  28   e  is formed. Each of the ends  32   e  and  34   e  may also be configured with a lace stopper member. 
     Portions of the shoelace  30   s  extending from the knots at the ends  32   e  and  34   e  toward the side opposite to the eyelet parts  28   e  will be respectively referred to as extension lace parts  32   j  and  34   j,  as illustrated in  FIG. 1 . The tips of the extension lace parts  32   j  and  34   j  may be free ends. Also, each of the tips of the extension lace parts  32   j  and  34   j  may be cut off at an appropriate length for each wearer. 
     Since the shape of a foot is different for each wearer, an appropriate length of each of the first portion  32  and the second portion  34  is also different. Accordingly, the lengths of the first portion  32  and the second portion  34  may desirably be changeable. Therefore, in the present embodiment, the lengths of the first portion  32  and the second portion  34  are made adjustable at the end  32   e  of the first portion  32  and the end  34   e  of the second portion  34 . 
     By changing the position of the knot at the end  32   e,    4   j  when the extension lace part  32   j  is made longer, the first portion  32  becomes shorter, and, when the extension lace part  32   j  is made shorter, the first portion  32  becomes longer. Also, by changing the position of the knot at the end  34   e,  when the extension lace part  34   j  is made longer, the second portion  34  becomes shorter, and, when the extension lace part  34   j  is made shorter, the second portion  34  becomes longer. As described previously, the tip side with respect to a knot may be cut to an appropriate length. Also, instead of forming a knot, a dial-type length adjustment mechanism may be provided, for example. In these cases, the lengths can be easily adjusted. 
     A route from the end  32   e  of the first portion  32  will be described. As illustrated in  FIG. 4 , the first portion  32  extends from the eyelet part  28   e   4  to the eyelet part  28   j   5 , from the eyelet part  28   j   5  to the eyelet part  28   j   1 , from the eyelet part  28   j   1  to the eyelet part  28   e   1 , and from the eyelet part  28   e   1  to the middle eyelet part  28   j   3 . In the first portion  32 , the portion from the eyelet part  28   j   5  to the eyelet part  28   j   1  is pulled out to the inner side to constitute a lead part  32   p.  In the lead part  32   p,  the clasp  36  is provided. Each portion extending between an inner eyelet part  28   j  and an outer eyelet part  28   e  in the first portion  32  will be referred to as an inward-outward extending part  32   k.    
     A route from the end  34   e  of the second portion  34  will be described. As illustrated in  FIG. 4 , the second portion  34  extends from the eyelet part  28   e   2  to the eyelet part  28   j   2 , from the eyelet part  28   j   2  to the eyelet part  28   j   4 , from the eyelet part  28   j   4  to the eyelet part  28   e   3 , and from the eyelet part  28   e   3  to the middle eyelet part  28   j   3 . In the second portion  34 , the portion from the eyelet part  28   j   2  to the eyelet part  28   j   4  is pulled out to the inner side to constitute a lead part  34   p.  In the lead part  34   p,  the clasp  36  is provided. Each portion extending between an inner eyelet part  28   j  and an outer eyelet part  28   e  in the second portion  34  will be referred to as an inward-outward extending part  34   k.    
     The lead parts  32   p  and  34   p  in this example pass through a passage within the clasp  36 . Accordingly, pulling the clasp  36  applies tension to the first portion  32  and the second portion  34 , thereby applying tightening force to the upper  20 . 
     The clasp  36  is disposed on both the first portion  32  and the second portion  34 . The clasp  36  is attached such as to be relatively movable with respect to the first portion  32  and the second portion  34 . Accordingly, by changing the positional relationship between the boundary  30   b  of the first portion  32  and the second portion  34  and the clasp  36 , one of the first portion  32  and the second portion  34  can be made shorter to strengthen the tightening force therein, and the other can be made longer to weaken the tightening force therein. 
     The first portion  32  and the second portion  34  are sectioned into front portions  32   f  and  34   f  located forward of the clasp  36 , and rear portions  32   b  and  34   b  located rearward of the clasp  36 , respectively. In other words, the clasp  36  is disposed between the front portions  32   f,    34   f  and the rear portions  32   b,    34   b.  By changing the positional relationship between the clasp  36  and the shoelace  30   s,  the tightening force in either the front portions  32   f,    34   f  or the rear portions  32   b,    34   b  can be weakened, and the tightening force in the other can be strengthened. This can adjust the tightening force distribution in a longitudinal direction. 
       FIG. 5  is also referred to.  FIG. 5  is a plan view that illustrates positional relationships among the shoelace  30   s,  and the thenar eminence and the hypothenar eminence of a wearer. In  FIG. 5 , a straight line connecting the hypothenar eminence and the thenar eminence of the wearer is denoted by a reference character Lb. The straight line Lb is inclined by 15 degrees in the clockwise direction with respect to a width direction in plan view. 
     In the present embodiment, the rearmost part of the first portion  32  constitutes a top line  30   h  of the tightening part  30 , and the forefront part of the first portion  32  constitutes a bottom line  30   j  of the tightening part  30 . In each of the top line  30   h  and the bottom line  30   j  in the example of 
       FIG. 4 , the lateral side is positioned rearward of the medial side. In plan view, each of the top line  30   h  and the bottom line  30   j  is inclined by a predetermined angle On with respect to a width direction. The predetermined angle On may be an angle approximate to the positional relationship between the thenar eminence and the hypothenar eminence of a wearer in plan view, such as 15 degrees. 
     Also, in plan view, the positional relationship between the eyelet part  28   j   5  and the eyelet part  28   e   4 , through which the top line  30   h  passes, is approximate to the positional relationship between the thenar eminence and the hypothenar eminence of a wearer. In other words, a straight line connecting the eyelet part  28   j   5  and the eyelet part  28   e   4  extends substantially in parallel with the straight line connecting the thenar eminence and the hypothenar eminence. Also, in plan view, the positional relationship between the eyelet part  28   j   1  and the eyelet part  28   e   1 , through which the bottom line  30   j  passes, is approximate to the positional relationship between the thenar eminence and the hypothenar eminence of a wearer. In other words, a straight line connecting the eyelet part  28   j   1  and the eyelet part  28   e   1  extends substantially in parallel with the straight line connecting the thenar eminence and the hypothenar eminence. 
     To absorb impact and reduce fatigue during walking, for example, it is desirable to maintain a transverse arch from the thenar eminence to the hypothenar eminence. Accordingly, the tightening part  30  in the present embodiment is configured such that the tightening force acts in directions in which the thenar eminence and the hypothenar eminence come closer to each other. Specifically, the tightening part  30  is configured such as to tighten the upper  20  in directions substantially parallel with the straight line connecting the hypothenar eminence and the thenar eminence. 
     More specifically, an average of the extending directions of the inward-outward extending parts  32   k  and  34   k  located between the inner eyelet parts  28   j  and the outer eyelet parts  28   e  is set to be substantially parallel with the straight line connecting the hypothenar eminence and the thenar eminence. The straight line connecting the thenar eminence and the hypothenar eminence is inclined by about 15 degrees with respect to a width direction such that the lateral side is positioned rearward of the medial side. 
     In the first portion  32 , the inward-outward extending part  32   k  extending from the eyelet part  28   e   1  to the middle eyelet part  28   j   3  is inclined such that the medial side is positioned rearward of the lateral side. Also, in the second portion  34 , the inward-outward extending part  34   k  extending from the eyelet part  28   e   3  to the middle eyelet part  28   j   3  is greatly inclined such that the lateral side is positioned rearward of the medial side. Including these, an average of the extending directions (i.e., directions of tension) of the inward-outward extending parts  32   k  and  34   k  is inclined by about 15 degrees with respect to a width direction. 
     There will now be described top lines of the wearing opening  20   b.  The top lines on the lateral side and the medial side of the wearing opening  20   b  may be provided symmetrically. However, in the present embodiment, the top lines on the lateral side and the medial side are provided asymmetrically as illustrated in  FIG. 1 , in terms of ease of wearing. When putting on a shoe, the wearer often inverts the foot (with the hallux side positioned higher) to insert the foot into the wearing opening  20   b.  Accordingly, the wearer can put on the shoe more easily when the hallux side of the wearing opening  20   b  is open. Therefore, a top line  20   e  on the medial side (hallux side) of the wearing opening  20   b  in the upper  20  is positioned forward of a top line  20   j  on the lateral side of the wearing opening  20   b.  The top line  20   j  is positioned near the eyelet part  28   e   4  at which the end  32   e  on the rear side of the shoelace  30   s  is fixed. As illustrated in  FIG. 2 , the top line  20   j  is positioned higher than the top line  20   e.    
     There will now be described the features of the shoe  100  of the present embodiment configured as described above. The shoe  100  includes the sole  10 , the upper  20  provided above the sole  10  to accommodate a foot, the tightening part  30  that applies tightening force to the upper  20 , and the force transmitter  18  that transmits tightening force from the tightening part  30  to a lower part of the midfoot portion  20   m  of the upper  20 . With this configuration, the tightening part  30  can be fixed to the lower part of the midfoot portion  20   m  of the upper  20 , contributing to evening of the tightening force distribution in a longitudinal direction. 
     The force transmitter  18  includes the clasp  36  that detachably fixes the tightening part  30  to the upper  20 . In this case, with a simple configuration, the tightening force can be transmitted to the upper  20 . 
     The clasp  36  is fixed to the upper  20 , around the boundary part  20   h  between the upper  20  and the sole  10 . In this case, the tightening force can be certainly applied to a foot, contributing to the evening of the tightening force distribution. 
     The tightening part  30  includes the first portion  32  and the second portion  34  formed continuously with each other. The clasp  36  is provided on both the first portion  32  and the second portion  34 . By changing the positional relationship between the boundary  30   b  of the first portion  32  and the second portion  34  and the clasp  36 , the tightening force in one of the first portion  32  and the second portion  34  can be strengthened, and the tightening force in the other of the first portion  32  and the second portion  34  can be weakened. In this case, the amount of tightening can be adjusted near the wearing opening  20   b  and on the toe side. 
     The tightening part  30  is a shoelace. The upper  20  includes the eyelet parts  28  through which the first portion  32  or the second portion  34  passes. The end  32   e  of the first portion  32  and the end  34   e  of the second portion  34  are fixed to the lateral side of the upper  20 . The clasp  36  is fixed to the lateral side. In this case, the shoelace can be easily tightened from the medial side toward the lateral side. This can contribute to the evening of the tightening force distribution. 
     The eyelet parts  28  include the outer eyelet parts  28   e  provided on the lateral side and the inner eyelet parts  28   j  provided on the medial side. The number of inner eyelet parts  28   j  is larger than the number of outer eyelet parts  28   e.  In this case, tightening can be performed dispersedly at multiple positions equal in number to the inner eyelet parts  28   j,  contributing to the evening of the tightening force distribution. 
     The lengths of the first portion  32  and the second portion  34  are adjustable at at least one of the clasp  36 , the end  32   e  of the first portion  32 , and the end  34   e  of the second portion  34 . In this case, the length of the shoelace  30   s  can be adjusted based on the foot size. 
     The rearmost part of the first portion  32  constitutes the top line  30   h  of the tightening part  30 , and the forefront part of the first portion  32  constitutes the bottom line  30   j  of the tightening part  30 . In each of the top line  30   h  and the bottom line  30   j,  the lateral side is positioned rearward of the medial side. In this case, a line corresponding to the bases of toes and the MP joints can be appropriately tightened. 
     The shoe includes the position adjustment mechanism  42  with which the fixed position of the clasp  36  can be shifted in a longitudinal direction. In this case, the clasp  36  can be fixed at an appropriate position in a longitudinal direction. 
     The top line  20   e  on the medial side of the wearing opening  20   b  in the upper  20  is positioned forward of the top line  20   j  on the lateral side of the wearing opening  20   b.  In this case, when a wearer puts on the shoe  100 , the medial side of the wearing opening  20   b  is opened, so that the wearing and removing of the shoe becomes easier. 
     The tightening part  30  tightens the upper  20  in a direction substantially parallel with a straight line connecting a hypothenar eminence and a thenar eminence. In this case, when a foot receives a load, force acts such that the hypothenar eminence and the thenar eminence are broadened and the transverse arch is deformed; however, tightening the foot such that the hypothenar eminence and the thenar eminence come closer to each other can contribute to the maintaining of the transverse arch. 
     An exemplary embodiment of the present invention has been described in detail. The abovementioned embodiment merely describes a specific example for carrying out the present invention. The embodiment is not intended to limit the technical scope of the present invention, and various design modifications, including changes, addition, and deletion of constituting elements, may be made to the embodiment without departing from the scope of ideas of the invention defined in the claims. In the aforementioned embodiment, matters to which design modifications may be made are described with the expression of “of the embodiment”, “in the embodiment”, or the like. However, it is not unallowable to make a design modification to a matter without such expression. Also, the hatching provided on the cross sections in the drawings is not provided to limit the materials of the objects with the hatching. 
     (Modifications) 
     In the following, modifications will be described. In the drawings and description of the modifications, like reference characters denote like or corresponding constituting elements and members in the embodiment. Repetitive description already provided in the embodiment will be omitted as appropriate, and configurations different from those in the embodiment will be intensively described. 
     (First Modification) 
     Although the embodiment describes an example in which the tightening part  30  is constituted only by the shoelace  30   s,  the present invention is not limited thereto. The tightening part  30  may include a belt-shaped member.  FIG. 6  is a plan view that schematically illustrates a shoe  200  according to the first modification and corresponds to  FIG. 1 .  FIG. 7  is a side view of the shoe  200  and corresponds to  FIG. 3 . The present modification differs from the embodiment in that the tightening part  30  includes a belt part  30   m  in addition to the shoelace  30   s  and that first and second hook-and-loop fasteners  36   m  and  38   m  are employed as the clasp  36 , instead of a buckle. 
     As illustrated in  FIG. 6 , a base end  30   n  of the belt part  30   m  is fixed to the medial portion  22  of the upper  20 . The belt part  30   m  has a thin rectangular shape extending from the base end  30   n  in a width direction, and, on a leading end  30   p  thereof, the first hook-and-loop fastener  36   m  is provided. Near the leading end  30   p  of the belt part  30   m,  a lead support  30   q  is formed such that the lead parts  32   p  and  34   p  of the shoelace  30   s  pass therethrough. The lead support  30   q  is a passage through which the lead parts  32   p  and  34   p  pass in a longitudinal direction. 
     The second hook-and-loop fastener  38   m  is provided on the upper  20 , around the boundary part  20   h  between the upper  20  and the sole  10 . One of the first hook-and-loop fastener  36   m  and the second hook-and-loop fastener  38   m  has a hook face, and the other thereof has a loop face. Accordingly, the first hook-and-loop fastener  36   m  can be detachably fixed onto the second hook-and-loop fastener  38   m.  Fixing the first hook-and-loop fastener  36   m  onto the second hook-and-loop fastener  38   m  can tighten the upper  20 . Also, detaching the first hook-and-loop fastener  36   m  from the second hook-and-loop fastener  38   m  can release the tightening of the upper  20 . 
     The first modification describes an example in which the tightening part  30  is constituted by a single belt-shaped member. However, the present invention is not limited thereto, and the tightening part  30  may include multiple belt-shaped members. For example, the tightening part  30  may include two or more thin rectangular portions extending in a width direction. In this case, the base ends of the two or more thin rectangular portions may be connected with each other or may be separated from each other. Also, the leading ends of the two or more thin rectangular portions may be connected with each other or may be separated from each other. 
     (Second Modification) 
     With reference to  FIG. 8 , a shoe  300  according to the second modification will be described.  FIG. 8  is a side view that schematically illustrates the shoe  300  according to the second modification and corresponds to  FIG. 3 . The force transmitter  18  in the present modification includes the clasp  36  for detachably fixing the shoelace  30   s  to the upper  20 , and a member for drawing a middle part of the shoelace  30   s  toward the lower part of the midfoot portion  20   m  of the upper  20 . The present modification differs from the embodiment particularly in the fixing structure for the lead parts  32   p  and  34   p  in the tightening part  30 , and the other configurations are similar to those in the embodiment. Accordingly, the fixing structure for the lead parts  32   p  and  34   p  will be mainly described. The fixing structure for the lead parts  32   p  and  34   p  in the present modification includes an extension part  44  and a middle support  46 . The middle support  46  exemplifies the member for drawing the middle part of the shoelace  30   s  and corresponds to the force transmitter. 
     (Extension Part) 
     The embodiment describes an example in which the lead parts  32   p  and  34   p  of the shoelace  30   s  are connected directly to the clasp  36 . In the present modification, the lead parts  32   p  and  34   p  are connected to the clasp  36  via the extension part  44 . The extension part  44  is a belt-shaped member formed of a flexible material, such as cloth. On the base end side of the extension part  44 , a loop part  44   b  is provided such that the lead parts  32   p  and  34   p  pass therethrough. The loop part  44   b  may be formed by folding back, for example. In the loop part  44   b,  the loop need not necessarily be closed, and part of the loop may be open. On the base end side of the extension part  44 , a hook may be provided instead of the loop part  44   b.  On the leading end side of the extension part  44 , the clasp  36  is fixed. The clasp  36  is a male part of a resin buckle. 
     The fixed position of the receiving part  38  is not particularly limited. In the present modification, the receiving part  38  is fixed to the lateral side of the rearfoot portion  20   g  in the upper  20 . Specifically, the receiving part  38  is fixed onto or above a line that constitutes the contour of the upper  20  in top view. The receiving part  38  may be fixed below the line. Also, although the receiving part  38  may be fixed directly to the upper  20 , the receiving part  38  in this example is fixed to the upper  20  via a belt  38   b.  The receiving part  38  may be fixed directly to the upper  20 . The receiving part  38  is a female part of a resin buckle. 
     The middle support  46  supports bundled middle regions of the lead parts  32   p  and  34   p  of the shoelace  30   s  so as to concentrate the directions of tension (tightening force) of the lead parts  32   p  and  34   p  at the lower part of the midfoot portion  20   m  of the upper  20 . In other words, the middle support  46  draws middle parts  32   q  and  34   q  of the lead parts  32   p  and  34   p  toward the lower part of the midfoot portion  20   m  to support the middle parts  32   q  and  34   q.    
     The configuration of the middle support  46  is not particularly limited, as long as it can apply, to the lead parts  32   p  and  34   p,  tension toward a predetermined position. In the example of  FIG. 8 , the middle support  46  is a member including a loop part  46   b  through which the middle parts  32   q  and  34   q  of the lead parts  32   p  and  34   p  are made to pass, and the middle support  46  applies frontward and downward tension to the middle parts  32   q  and  34   q.  The middle support  46  is a belt-shaped member formed of an elastic or flexible material, such as cloth, and the loop part  46   b  is formed by folding back the belt-shaped member. In the loop part  46   b,  the loop need not necessarily be closed, and part of the loop may be open. Also, the middle support  46  may include, instead of the loop part  46   b,  a hook through which the middle parts  32   q  and  34   q  are made to pass, or a projection around which the middle parts  32   q  and  34   q  are hooked. The position of an upper edge of the loop part  46   b  may desirably be below the contour of the upper. 
     A base end  46   a  of the middle support  46  is fixed to the upper  20 , around the boundary part  20   h  between the upper  20  and the sole  10 . The loop part  46   b  is positioned on the upper rear side with respect to the base end  46   a.  When the clasp  36  and the receiving part  38  are arranged on the rear side, the abovementioned positional relationship between the base end  46   a  and the loop part  46   b  of the middle support  46  can apply, to the upper, the tension (tightening force) of the lead parts  30   s  and  34   p  among the lead parts more effectively. When the clasp  36  and the like are provided on the front side, it is preferable to dispose the loop part  46   b  on the upper front side with respect to the base end  46   a.    
     The use of the fixing structure for the lead parts  32   p  and  34   p  will be described. When the extension part  44 , connected with the lead parts  32   p  and  34   p,  and the clasp  36 , connected with the leading end side of the extension part  44 , have been made to pass through the loop part  46   b  of the middle support  46 , by connecting the clasp  36  to the receiving part  38 , the tightening part  30  can tighten the upper  20 . In this state, tension toward the lower part of the midfoot portion  20   m  acts on the lead parts  32   p  and  34   p,  thereby reducing deviation in the tightening force distribution in a longitudinal direction of the upper  20 . Also, by detaching the clasp  36  from the receiving part  38 , the tightening part  30  is placed in a non-tightening state, so that the tightening of the upper  20  is released. 
     The middle support  46  may be configured with a position adjustment mechanism such as to be movable in the longitudinal directions. 
     The clasp  36  and the receiving part  38  may be configured as hook-and-loop fasteners, hooks, magnets, or the like, instead of a resin buckle. 
     (Other Modifications) 
     Although the embodiment describes an example in which the number of inner eyelet parts  28   j  is larger than the number of outer eyelet parts  28   e,  the present invention is not limited thereto. The numbers may be equal, or the number of inner eyelet parts  28   j  may be smaller than the number of outer eyelet parts  28   e.    
     Although the embodiment describes an example in which a single clasp  36  is provided, the present invention is not limited thereto and multiple clasps may be provided. Also, the clasp may be configured to be fixable to multiple positions in the upper. Also, the receiving part may be configured to be attachable and detachable, and the attachment parts therefor may be provided at multiple positions. Further, separate clasps may be provided respectively in the first portion  32  and the second portion  34 . 
     Although the embodiment describes an example in which the clasp  36  is fixed to the upper  20 , the present invention is not limited thereto. For example, the clasp  36  may be fixed to a portion extending from the sole  10 . 
     Although the embodiment describes an example in which the eyelet parts  28  are grommets, the present invention is not limited thereto. Each eyelet part  28  has only to have a structure through which the shoelace  30   s  can be made to pass. Alternatively, the eyelet parts  28  may be lace hook parts, such as hooks, instead of holes. The hole edge of each eyelet part  28  may be reinforced by a reinforcement member or may be made thicker than the vicinity thereof by means of buttonhole stitches, for example. 
     Although the embodiment describes an example in which the tightening part  30  includes a single shoelace  30   s,  the present invention is not limited thereto. The tightening part may include multiple shoelaces. Also, when comfort in wearing is considered important, such as in the case of shoes for children or elderly persons, the shoelace  30   s  may be formed of a material with high elasticity or flexibility. Meanwhile, when the stability is considered important, such as in the case of sports shoes, the shoelace  30   s  may be formed of a material with low elasticity or flexibility. 
     Although the embodiment describes an example in which the receiving part  38  is disposed on the lateral side, the receiving part  38  may be disposed on the medial side. Also, over the clasp  36  and the receiving part  38 , a protection cover may be provided to prevent entering of foreign matter, such as a small stone. Also, the clasp  36  may include a mechanism part for adjusting the lengths of the first portion  32  and the second portion  34 . 
     Each of the abovementioned modifications provides functions and effects similar to those of the aforementioned embodiment. 
     Optional combinations of the aforementioned embodiment and modifications may also be practiced as additional embodiments of the present invention. Such an additional embodiment made by combination has the effect of each of the combined embodiment and modifications. 
     INDUSTRIAL APPLICABILITY 
     The present invention relates to a tightening part of a shoe and is applicable to a shoe. 
     REFERENCE SIGNS LIST 
       10  sole 
       20  upper 
       20   b  wearing opening 
       20   e,    20   j  top line 
       20   h  boundary part 
       20   m  midfoot portion 
       28  eyelet part 
       28   e  outer eyelet part 
       28   j  inner eyelet part 
       30  tightening part 
       30   b  boundary 
       30   h  top line 
       30   j  bottom line 
       30   s  shoelace 
       32  first portion 
       34  second portion 
       32   e,    34   e  end 
       36  clasp 
       42  position adjustment mechanism 
       100 ,  200 ,  300  shoe