Patent Publication Number: US-2019175380-A1

Title: Device for correcting nail deformity

Description:
TECHNICAL FIELD 
     The present invention relates to nail deformity correction devices and, in particular, a device for correcting nail deformity such as a so-called ingrown nail of a foot cutting into a flesh part between the nail and a fingertip as it grows so that one and/or the other side edge end of the nail rolls inside. 
     BACKGROUND ART 
     In a conventional technology as a background of the present invention, a device for nail straightening has been suggested. In a type having at least two hook-shaped force introduction members (1, 1 a,  1 b ) hooked on a lower side of nail edge parts (3 a,  3 b ) and at least one coupling member (2, 2 a,  2 b ), the coupling member (2, 2 a,  2 b ) is flexible and firmly attached to the force introduction members (1, 1 a,  1 b ). In this case, the coupling member (2, 2 a,  2 b ) is shortened to cause a tensile force adjustable in a stepless manner at the force introduction members (1, 1 a,  1 b ). The tensile force acts on the nail edge parts (3 a,  3 b ) to cause bending moment to a nail plate (for example, refer to Patent Literature 1). 
     In this conventional device for nail straightening, the entirety is formed of a wire material, and a region of the force introduction members (1, 1 a,  1 b ) is formed of a wire material made of spring steel and is elastically deformable. Also, a region of the coupling member (2, 2 a,  2 b ) is formed of a soft wire material capable of molten binding, and is formed so as to be plastically deformable. The force introduction members and the coupling member have different thickness of wire material. 
     In this conventional technology, an embodiment including a hook-shaped part (1, 1 a,  1 b,  13, 15) or an eye (7) at an end of the coupling member (2 a,  2 b ) is disclosed. Also in this conventional technology, in order to stabilize the position of the device for nail straightening, that is, to prevent the end of the hook-shaped part (1, 1 a,  1 b,  13, 15) from being twisted or rotated to come off from the lower side of nail edge part (3 a,  3 b ) when the device is attached to the nail or during treatment, an embodiment including any of a coated part 17, a bent-out part 18, and a molded portion 19 provided on a side part as a member for positional stabilization is disclosed. 
     In this conventional technology, securing of the device by an appropriate tool is depicted in FIG. 7. The coupling members (2, 2 a,  2 b ) are guided as being partially wound around a lower pin (12) of the tool, and the eye (7 a,  7 b ) is hooked on an upper pin (11) of the tool. By enlarging a space between the pins (11, 12) both in a stepless manner, that is, consecutively, the space between the hook-shaped members (1 a,  1 b ) both is consecutively shortened until a desired tensile force is achieved. In this manner, in order to establish (fix) the defined space between the hook-shaped members (1 a,  1 b ) both, that is, a defined length of the coupling members, the tool (10) spreads at least 180° in a clockwise direction, thereby making both of the coupling members (2, 2 a,  2 b ) perpetually coupled together. Then, after this device for nail straightening is attached to the nail, an excessive wire material portion of the coupling members (2, 2 a,  2 b ) is cut out by, for example, a cutter. 
     Also in this conventional technology, fastening the coupling members (2, 2 a,  2 b ) and fixing their lengths may be performed by twining the coupling members (2, 2 a,  2 b ) together. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Unexamined Patent Application No. 2007-289712 (for example, FIG. 1 to FIG. 12) 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in this conventional technology, to fastening the coupling members (2, 2 a,  2 b ), a work of twisting the coupling members by using the dedicated tool is required. Also when a dedicated tool is not used, a work of twining the coupling members (2, 2 a,  2 b ) together is required. Thus, in this conventional technology, burdensome efforts are required to attach the device to the nail, and the attachment time is also long. 
     Also in this conventional technology, the force introduction members (1, 1 a,  1 b ) and the coupling members (2, 2 a,  2 b ) are coupled as metal wire materials having different degrees of elasticity and different thickness. Thus, when the above-described operation of fastening the coupling members (2, 2 a,  2 b ) and fixing the length is performed, that is, when the work of twisting or twining the coupling members is performed, a boundary portion between a force introduction member (1, 1 a,  1 b ) and a coupling member (2, 2 a,  2 b ) may be broken by bending. Furthermore, when a user changes the shape of a hook in accordance with the thickness and shape of the nail by using special pliers, a boundary portion between a hook portion and any of the above-described members for position stabilization (for example, the coated part 17, the bent-out part 18, and the molded portion 19) may be broken by bending. 
     Also, in the above-describe conventional technology, when the excessive wire material portion of the coupling members (2, 2 a,  2 b ) is cut out, an edge of its cutout end surface is oriented above the nail. Thus, the hand may be damaged by the edge portion of the cutout end surface. Furthermore, when socks are worn after this device is attached, the edge of the cutout end surface may damage the socks. 
     Also, in this conventional technology, reversibility is kept before the excessive wire material portion of the coupling members (2, 2 a,  2 b ) is cut out, that is, the nail tensile force can be loosened. However, reversibility is lost after the excessive wire material portion is cut out, that is, it is extremely difficult to loosen the nail tensile force and adjust the tensile force again. 
     Hence, a main object of the present invention is to provide a nail deformity correction device easily attachable in an effort-saving manner without damage on the device at the time of attachment. 
     Also, another object of the present invention is to provide a nail deformity correction device in which a straightening force to be applied to the nail can be easily changed even after the device is attached. 
     Solution to Problem 
     The present invention according to claim  1  is directed to a nail deformity correction device including a first straightening member and a second straightening member which correct deformity of a finger nail of a foot in cooperation with each other, the first straightening member including a belt part having a serration part, and a first latching part disposed at one end of the belt part in a length direction to be latched at one end edge of the deformed nail in a width direction, and the second straightening member including a fastening locking part having an insertion hole into which the belt part is inserted to fasten and lock the belt part to the deformed nail, a lock nail part disposed inside the fastening locking part to be locked to the serration part of the belt part inserted into the insertion hole to inhibit the belt part from returning to a direction opposite to an inserting direction of the belt part, and a second latching part formed to extend from the fastening locking part to the inserting direction of the belt part to be latched at another end edge of the deformed nail in the width direction. 
     Since the present invention according to claim  1  has the above-described structure, the first latching part of the first straightening member is latched at one end edge of the deformed nail in the width direction, the second latching part of the second straightening member is latched at the other end edge of the nail in the width direction. Furthermore, the other end side (free end side) of the belt part in the length direction is inserted into the insertion hole of the lock nail part of the fastening locking part, and the free end side of the belt part is pulled, thereby allowing the belt part to be fastened to the nail surface. 
     In this case, the one end edge and the other end edge sides of the deformed nail in the width direction are pulled upward by the first latching part and the second latching part, respectively, to a direction opposite to the ingrowing direction of the deformed nail, for example, “ingrown nail”. This tensile force can be increased as the length of the belt part to be pulled out from the insertion hole of the fastening locking part is longer, that is, a length between one end part of the belt part in the length direction and a portion of the belt part locked by the lock nail part is shorter. By contrast, this tensile force can be decreased as the length of the belt part to be pulled out from the insertion hole of the fastening locking part is shorter, that is, the length between one end part of the belt part in the length direction and the portion of the belt part locked by the lock nail part is longer. Therefore, this tensile force can be adjusted as appropriate in accordance with the size and shape of the deformed nail, the degree of a curve (the degree of deformation) of the ingrown nail, and so forth. 
     And, the tensile force adjusted by this adjustment is retained by the lock function of the lock nail part inhibiting the belt part from returning to the direction opposite to the inserting direction of the belt part. Thus, the tensile force to the direction opposite to the ingrowing direction of the ingrown nail continuously acts at both end edges of the ingrown nail in the width direction, and a decrease in this tensile force is prevented. Therefore, according to the nail deformity correction device, deformity of the nail such as ingrown nail can be straightened. 
     Also as described above, when the belt part is fastened by the fastening locking part, the belt part makes contact with the surface of the nail and pressurizes the nail downward. Thus, in particular, with the belt part as a center, the first latching part, the fastening locking part, and the second latching part are each stably attached to the surface of the nail without being shifted or moved. 
     Since the present invention has the structure and operations described above, compared with the conventional technology described in Patent Literature 1, the work of twisting coupling members (2, 2 a,  2 b ) by using the dedicated tool or the work of twining the coupling members (2, 2 a,  2 b ) when not using the dedicated tool is not required. Thus, in the nail deformity correction device of the present invention, burdensome efforts to attach this device to the nail are not required, and the attachment time is also short. Also in the conventional technology, when the work of twisting or twining the coupling members is performed, a boundary portion between a force introduction member (1, 1 a,  and 1 b ) and a coupling member (2, 2 a,  2 b ) may be broken by bending. By contrast, in the present invention, these twisting work and twining work are not required, and thus inconveniences such as breakage of the device itself by bending are eliminated. 
     That is, according to the present invention, it is possible to provide a nail deformity correction device easily attachable in an effort-saving manner without damage on the device at the time of attachment, capable of causing an appropriate straightening force to act over a long period, and capable of causing a straightening force to act as intended. 
     The present invention according to claim  2  is an invention dependent from the invention according to claim  1 , and is directed to the nail deformity correction device in which the belt part further includes a belt part main body, a first support part disposed at one end of the belt part main body in a length direction to support the first latching part, and a lead part disposed at another end of the belt part main body in the length direction and having a free end at a tip, to guide the belt part to the second straightening member, and the serration part is disposed between the first support part and the lead part and at an intermediate part on both or either one of main surfaces including one main surface and another main surface of the belt part main body in the length direction, and the serration part is disposed so as to be opposed to the deformed nail surface when the first latching part is latched at one end edge of the deformed nail in the width direction. 
     Since the present invention according to claim  2  has the above-described structure, in addition to the operations and effects of the invention according to claim  1 , the first support part can stably support the first latching part to the nail surface and, furthermore, the lead part can easily guide the belt part to the second straightening part. Also, since the serration part is disposed so as to be opposed to the deformed nail surface, when the nail deformity correction device of the present invention is attached to the deformed nail, the serration part makes contact with the deformed nail surface. In this case, the serration part exerts a shift-preventing function of preventing a positional shift due to slipping of the belt part on the nail surface. 
     The present invention according to claim  3  is an invention dependent from the invention according to claim  1  or claim  2 , and is directed to the nail deformity correction device in which the serration part includes a sawtooth part having an upright surface extending at a substantially right angle with respect to the one main surface and the other main surface of the belt part and a tilted surface tilted toward the inserting direction of the belt part, and the lock nail part includes a nail piece having an upright engaging surface to be engaged with the upright surface of the sawtooth part and a tilted engaging surface to be engaged with the tilted surface of the sawtooth part. 
     Since the present invention according to claim  3  has the above-described structure, the upright surface of the sawtooth part and the upright engaging surface of the lock nail part can be engaged together, and the tilted surface of the sawtooth part and the tilted engaging surface of the lock nail part can be engaged together. Thus, when the belt part is inserted into the insertion hole of the fastening locking part, the tilted engaging surface of the lock nail part is pressurized by the tilted surface of the sawtooth part to cause the belt part to move to the inserting direction. Also, when the belt part is about to return to the direction opposite to the inserting direction of the belt part, the upright surface of the sawtooth part and the upright engaging surface of the lock nail part are engaged, and a surface contact is made with that engaging area. Thus, the lock function against the return force applied to the belt part is firmly exerted. 
     The present invention according to claim  4  is an invention dependent from the invention according to any one of claim  1  to claim  3 , and is directed to the nail deformity correction device in which the lock nail part is disposed inside the fastening locking part via a cantilever-like movable piece. 
     Since the present invention according to claim  4  has the above-described structure, one end side of the lock nail part serves as a fixed end supported to the inside of the fastening locking part, and the other end thereof serves as a free end to become in a movable state. If the present invention is the invention dependent from claim  3 , when the belt part is inserted into the insertion hole of the fastening locking part, the tilted engaging surface of the lock nail part is pressurized as sliding over the tilted surface of the sawtooth part to be warped to the inserting direction of the belt part. Thus, the belt part can move through the insertion hole to the inserting direction. On the other hand, when the belt part is tried to return to the direction opposite to the inserting direction of the belt part, the upright surface of the sawtooth part and the upright engaging surface of the lock nail part are engaged, and a resistance force acts against the return force of the belt part, thereby locking the return of the belt part. 
     The present invention according to claim  5  is an invention dependent from the invention according to any one of claim  1  to claim  4 , and is directed to the nail deformity correction device in which the movable piece includes a hinge part, and the lock nail part is supported so as to freely rock to a direction orthogonal to the inserting direction of the belt part. 
     Since the present invention according to claim  5  has the above-described structure, the lock nail part is disposed inside the fastening locking part via the hinge part as a cantilever-like movable piece. Thus, the present invention has operations and effects similar to those of the invention according to claim  4 . 
     The present invention according to claim  6  is an invention dependent from the invention according to any one of claim  3  to claim  5 , and is directed to the nail deformity correction device in which, when an angle at which the upright surface and the tilted surface of the sawtooth part cross is taken as θ B , the θ B  is set so that 45°&lt;θ B &lt;60°, when an angle at which the upright engaging surface and the tilted engaging surface of the lock nail part cross is taken as θ L , the θ L  is set so that 45°&lt;θ L &lt;60°, and, furthermore, it is set so that the θ B =the θ L . 
     Since the present invention according to claim  6  has the above-described structure, when the belt part is inserted into the insertion hole of the fastening locking part, a tilted angle between the tilted surface of the sawtooth part and the tilted engaging surface of the lock nail part is a tilted angle suitable for the belt part to move to the inserting direction. Thus, the belt part can easily move to the fastening direction via the insertion hole of the fastening locking part and, in turn, fastening of the belt part by the fastening locking part onto the nail surface is facilitated. 
     The present invention according to claim  7  is an invention dependent from the invention according to any one of claim  1  or claim  2 , and is directed to the nail deformity correction device in which the fastening locking part further includes an activation piece connected to the lock nail part and exposed to outside the fastening locking part, and the activation piece releases a locked state between the serration part and the lock nail part by making the activation piece movable in a direction orthogonal to the inserting direction of the belt part and releasing locking between the serration part and the lock nail part. 
     Since the present invention according to claim  7  has the above-described structure, by making the activation piece movable in the direction of releasing locking between the serration part and the lock nail part, a locked state between the serration part and the lock nail part can be released. That is, the belt part can be moved to a direction opposite to the inserting direction of the belt part. Thus, according to the present invention, even after the device of the present invention is attached to the nail surface, the belt part is moved as appropriate from the insertion hole of the fastening locking part to the direction opposite to the inserting direction to once loosen fastening of the belt part and adjust the strength of fastening, thereby allowing the straightening force applied to the nail surface to be freely and easily changed. Furthermore, according to the present invention, the belt part can be pulled out from the insertion hole of the fastening locking part for reuse of the first straightening member once used. 
     The present invention according to claim  8  is an invention dependent from the invention according to any one of claim  3  to claim  6 , and is directed to the nail deformity correction device in which the fastening locking part further includes an activation piece connected to the lock nail part and exposed to outside the fastening locking part, and the activation piece releases an engaged state between the upright surface of the sawtooth part and the upright engaging surface of the lock nail part and an engaged state between the tilted surface of the sawtooth part and the engaging tilted surface of the lock nail part by making the activation piece movable in a direction orthogonal to the inserting direction of the belt part and isolating an engagement between the sawtooth part and the lock nail part. 
     Since the present invention according to claim  8  has the above-described structure, by making the activation piece movable, the engaged state between the upright surface of the sawtooth part and the upright engaging surface of the lock nail part and the engaged state between the tilted surface of the sawtooth part and the engaging tilted surface of the lock nail part can be released. Thus, also in the present invention, operations and effects similar to those of the invention according to claim  7  can be exerted. 
     The present invention according to claim  9  is an invention dependent from the invention according to any one of claim  1  to claim  8 , and is directed to the nail deformity correction device in which side wall parts are disposed on both side surface of the belt part in a width direction along the length direction of the belt part where at least the serration part is disposed, and a constricted part constricted to the width direction of the belt part is formed partially on each of the side wall parts so as to be opposed to each other in the width direction of the belt part. 
     Since the present invention according to claim  9  has the above-described structure, in the present invention, even if a thin portion with a decreased strength is formed on the belt part due to disposition of the serration part, the side wall parts can solve the inconvenience of this decrease in strength. Also, the constricted parts have a function as nipping parts for nipping the belt part when the belt part is inserted into the insertion hole of the fastening locking part, thereby allowing the belt part to be easily inserted into the insertion hole of the fastening locking part. The present invention according to claim  10  is an invention dependent from the invention according to any one of claim  2  to claim  9 , and is directed to the nail deformity correction device in which the lead part of the belt part is formed so as to be in a tapered shape and have a thin cross section. 
     Since the present invention according to claim  10  has the above-described structure, when the lead part is inserted into the insertion hole of the fastening locking part, the lead part can easily guide the belt part to the insertion hole of the fastening locking part without being interfered by the lock nail part of the fastening locking part. 
     The present invention according to claim  11  is an invention dependent from the invention according to any one of claim  2  to claim  10 , and is directed to the nail deformity correction device in which the first latching part includes a first insert part supported by the first support part, the fastening locking part further includes a second support part provided to extend from an end edge part of the fastening locking part on an exit side of the insertion hole to the inserting direction of the belt part, and the second latching part includes a second insert part supported by the second support part. 
     Since the present invention according to claim  11  has the above-described structure, the first latching part is firmly supported by the first insert part to the first support part, and the second latching part is firmly supported by the second insert part to the second support part. Thus, the first latching part and the second latching part each have a stable latching function. 
     The present invention according to claim  12  is an invention dependent from the invention according to any one of claim  1  to claim  11 , and is directed to the nail deformity correction device in which the belt part and at least the lock nail part of the fastening locking part of the second straightening member are formed of a flexible plastic material, and the first latching part and the second latching part are each formed of an elastic metal material. Since the present invention according to claim  12  has the above-described structure, the operations and effects of the present invention according to claims  1  to  11  can be more effectively achieved. 
     Advantageous Effects of Invention 
     According to the nail deformity correction device of the present invention, a main effect can be achieved in which the device can be easily attached in an effort-saving manner without damage on the device at the time of attachment. In this case, the effect of the present invention is achieved in which an appropriate straightening force can be caused to act over a long period and a user-intended straightening force can be caused to act. Also, in addition to the main effect, another effect is also achieved in which the straightening force to be applied to the nail can be easily changed even after the device is attached. 
     The above-described objects and other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the present invention made with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view depicting one example of an embodiment of a first straightening member and a second straightening member of a nail deformity correction device according to the present invention. 
         FIG. 2  is a perspective view of the first straightening member and the second straightening member of the nail deformity correction device depicted in  FIG. 1  when viewed from a bottom side. 
         FIG. 3  is a plan view depicting one example of the first straightening member depicted in  FIG. 1  and  FIG. 2 . 
         FIG. 4  is a front view of the first straightening member depicted in  FIG. 3 . 
         FIG. 5  is a bottom view of the first straightening member depicted in  FIG. 3 . 
         FIG. 6(A)  is a left side view of the first straightening member depicted in  FIG. 3  and  FIG. 6(B)  is a right side view of the first straightening member depicted in  FIG. 3 . 
         FIG. 7  is a sectional view along a line A-A of  FIG. 5 . 
         FIG. 8  is a perspective view depicting one example of the second straightening member of the nail deformity correction device depicted in  FIG. 1  and  FIG. 2 . 
         FIG. 9  is a plan view of the second straightening member depicted in  FIG. 8 . 
         FIG. 10  is a bottom view of the second straightening member depicted in  FIG. 8 . 
         FIG. 11  is a front view of the second straightening member depicted in  FIG. 8 . 
         FIG. 12  is a right side view of the second straightening member depicted in  FIG. 8 . 
         FIG. 13  is a sectional view along a line B-B of  FIG. 9 . 
         FIG. 14  is a perspective view depicting one example of a second insert part of a second latching part depicted in  FIG. 8 . 
         FIG. 15  is a plan view depicting a state in which the first straightening member is inserted into the second straightening member. 
         FIG. 16  is a front view of the state depicted in  FIG. 15 . 
         FIG. 17  is a bottom view of the state depicted in  FIG. 15 . 
         FIG. 18  is a left side view of the state depicted in  FIG. 15 . 
         FIG. 19  is a sectional view along a line C-C of  FIG. 17 . 
         FIG. 20(A)  is an enlarged view of a D part of  FIG. 19  and  FIG. 20(B)  is an enlarged view of main parts of  FIG. 20(A) . 
         FIG. 21  is a perspective view depicting one example of a process of attaching the nail deformity correction device depicted in  FIG. 1  and  FIG. 2  to a deformed nail, in which, for example, the first latching part of the first straightening member is latched at one end edge of a nail in a width direction and the second latching part of the second straightening member is latched at the other end edge of the nail in the width direction. 
         FIG. 22  is a perspective view depicting a process of, after the process depicted in  FIG. 21 , inserting a belt part of the first straightening member is inserted into an insertion hole of a fastening locking part of the second straightening member and the belt part is locked by the fastening locking part at a position of being fastened to the deformed nail. 
         FIG. 23  is a perspective view depicting a process of, after the process depicted in  FIG. 22 , cutting out a superfluous portion of the belt part protruding from the insertion hole of the fastening locking part at an appropriate location by a cutting tool. 
         FIG. 24  is a perspective view depicting a process of, after the process depicted in  FIG. 23 , applying a coating material such as an ultraviolet curable resin material so as to cover a location where the superfluous portion of the belt part is cut out and a root side of the fastening locking part and the second latching part to form an application part. 
         FIG. 25  is a perspective view depicting a process of, after the process depicted in  FIG. 24 , irradiating the application part with ultraviolet rays by an ultraviolet LED or the like to cure the coating material. 
         FIG. 26  is a perspective view depicting a state after the process depicted in  FIG. 25 , in which the application part is formed as a coated part. 
         FIG. 27  is a perspective view depicting a modification example of the second latching part of the second straightening member that can be applied to the nail deformity correction device according to the present invention. 
         FIG. 28  is a plan view of the second straightening member depicted in  FIG. 27 . 
         FIG. 29  is a perspective view depicting a second insert part of a second latching part depicted in  FIG. 27  and  FIG. 28 . 
         FIG. 30  depicts another example of the embodiment of the nail deformity correction device according to the present invention, and is a perspective view depicting one example of a process of attaching a first straightening member and a second straightening member of the nail deformity correction device to a deformed nail. 
         FIG. 31  is perspective view depicting one example of the second straightening member to be applied to the nail deformity correction device depicted in  FIG. 30 . 
         FIG. 32(A)  is a sectional view depicting a state when the first straightening member is inserted into the second straightening member depicted in  FIG. 30  and  FIG. 32(B)  is an enlarged view of an E part of  FIG. 32(A) . 
         FIG. 33  is a sectional view of an operation state of releasing an engaged state between a sawtooth part of the first straightening member and a lock nail part of the second straightening member from the state depicted in  FIG. 32 . 
         FIG. 34  depicts a modification example of the second straightening member depicted in  FIG. 30  and  FIG. 31  and is an enlarged sectional view of main parts depicting a state in which the first straightening member is inserted into the second straightening member. 
         FIG. 35  depicts still another example of the embodiment of the nail deformity correction device according to the present invention and is a sectional view depicting a state in which the first straightening member of the nail deformity correction device is inserted into the second straightening member. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The main object of the present invention easily attachable in an effort-saving manner without damage on the device at the time of attachment has been achieved by providing a nail deformity correction device including a first straightening member and a second straightening member which correct deformity of a finger nail of a foot in cooperation with each other, the first straightening member including a belt part having a serration part, and a first latching part disposed at one end of the belt part in a length direction to be latched at one end edge of the deformed nail in a width direction, and the second straightening member including a fastening locking part having an insertion hole into which the belt part is inserted to fasten and lock the belt part to the deformed nail, a lock nail part disposed inside the fastening locking part to be locked to the serration part of the belt part inserted into the insertion hole to inhibit the belt part from returning to a direction opposite to an inserting direction of the belt part, and a second latching part formed to extend from the fastening locking part to the inserting direction of the belt part to be latched at another end edge of the deformed nail in the width direction. 
     Also, the other object in which the straightening force to be applied to the nail can be easily changed even after the device is attached has been achieved by providing a nail deformity correction device in which the fastening locking part further includes an activation piece connected to the lock nail part and exposed to outside the fastening locking part, and the activation piece releases a locked state between the serration part and the lock nail part by making the activation piece movable in a direction orthogonal to the inserting direction of the belt part and releasing locking between the serration part and the lock nail part. 
       FIG. 1  is a perspective view depicting one example of an embodiment of a first straightening member and a second straightening member of a nail deformity correction device according to the present invention, and  FIG. 2  is a perspective view when viewed from a bottom side. 
     A nail deformity correction device (may be hereinafter simply referred to as a “device” for convenience)  10  according to this embodiment includes, as depicted in  FIG. 1  and  FIG. 2 , a first straightening member  12  and a second straightening member  14  which correct deformity of a finger nail of a foot in cooperation with each other. The first straightening member  12  includes a belt part  18  having a serration part  16  on one main surface (back surface). At one end of the belt part  18  in a length direction, a first latching part  20  to be latched at one end edge of the deformed nail in a width direction is disposed. 
     The second straightening member  14  includes a fastening locking part  24  having an insertion hole  22  into which the belt part  18  is to be inserted to be fasten and lock the belt part  18  to the deformed nail. Inside the fastening locking part  24 , a lock nail part  26  is disposed which inhibits the belt part  18  from returning to a direction opposite to an inserting direction of the belt part  18 . The lock nail part  26  is disposed so as to be able to be locked to the serration part  16  of the belt part  18  inserted into the insertion hole  22 . Also, the second straightening member  14  includes a second latching part  28 , and the second latching part  28  is formed to extend from the fastening locking part  24  to the inserting direction of the belt part  18 , and is latched at another end edge of the deformed nail in the width direction. 
     Here, the first straightening member  12  and the second straightening member  14  are each described in detail. 
     First, the first straightening member  12  is described in detail with reference to, for example,  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 , and  FIG. 7 .  FIG. 3  is a plan view depicting one example of the first straightening member depicted in  FIG. 1  and  FIG. 2 ,  FIG. 4  is its front view,  FIG. 5  is its bottom view,  FIG. 6(A)  is its left side view,  FIG. 6(B)  is its right side view, and  FIG. 7  is a sectional view along a line A-A of  FIG. 5 . 
     The belt part  18  of the first straightening member  12  includes a band-shaped narrowly-elongated belt part main body  30 , as depicted in  FIG. 3 ,  FIG. 4 , and  FIG. 5 . The belt part main body  30  has a first support part  32  disposed at one end in its length direction. The first support part  32  is formed in a flat plate shape having, for example, a substantially triangular shape in a planar view, to support the first latching part  20  as depicted in  FIG. 3  and  FIG. 5 . 
     The first latching part  20  includes a stem part  34  as depicted in  FIG. 3  and  FIG. 5 . The stem part  34  has one end side in its axial direction supported by the first support part  32  and has a hook part  36  formed on the other end side in its axial direction as depicted in  FIG. 7 . 
     At the other end of the belt part main body  30  in a length direction, a lead part  38  is disposed with its tip as a free end  38 A. The lead part  38  is formed in a tapered shape of, for example, a isosceles triangle, in a planar view, as depicted in  FIG. 3  and  FIG. 5 . Furthermore, the lead part  38  is formed having a sectional shape with a material thickness thinner than the thickness of the lead part main body  30 , as depicted in  FIG. 4  and  FIG. 7 . 
     The serration part  16  is disposed between the first support part  32  and the lead part  38  at an intermediate part of one main surface (lower surface) of the belt part main body  30  in the length direction. The serration part  16  is disposed so as to be opposed to the deformed nail surface when the first latching part  20  is latched at one end edge of the deformed nail in the width direction. The serration part  16  may be formed on, in addition to the one main surface (lower surface) of the belt part main body  30 , the other main surface (upper surface), and is only required to be formed on a main surface opposed to the nail surface, that is, a main surface in contact with the nail surface. 
     This serration part  16  is formed of a sawtooth part  40  including, for example, a plurality of consecutive sawtooth pieces  40 A. The plurality of sawtooth pieces  40 A each have an upright surface  42  extending at a substantially right angle with respect to the one main surface (lower surface) and the other main surface (upper surface) of the belt part main body  30  and a tilted surface  44  tilted toward the inserting direction of the belt part main body  30 . When an angle at which the upright surface  42  and the tilted surface  44  of the sawtooth part  40  cross is taken as θ B , θ B  is set so as to be in a range of 45°&lt;θ B &lt;60°. 
     Also, in the belt part  18 , a right side wall part  46  and a left side wall part  48  are disposed on one and the other side surfaces, respectively, of the belt part main body  30  in the width direction. These right side wall part  46  and left side wall part  48  on both side surfaces of the belt part main body  30  in the width direction are disposed along the length direction of the belt part main body  30  where the sawtooth part  40  is disposed. These right side wall part  46  and left side wall part  48  are disposed along the length direction of the belt part main body  30  corresponding to at least a portion where the sawtooth part  40  is disposed. 
     Furthermore, the right side wall part  46  and the left side wall part  48  have, each partially in its length direction, a right-side constricted part  50  and a left-side constricted part  52 , respectively, constricted to the width direction of the belt part main body  30 . The right-side constricted part  50  and the left-side constricted part  52  are formed so as to be opposed to each other in the width direction of the belt part main body  30 . 
     The belt part main body  30 , the first support part  32 , the lead part  38 , and the sawtooth part  40  of the first straightening member  12  are integrally formed of a flexible material, for example, a plastic material. 
     Also, the stem part  34  and the hook part  36  of the first latching part  20  are integrally formed of an elastic material, for example, a metal material. Furthermore, the first latching part  20  includes a first insert part  37  as depicted in  FIG. 7 , and the first insert part  37  is insert-molded by, for example, injection molding, so as to be supported by the first support part  32 . In this case, on a root part side of the stem part  34  of the first latching part  20 , that is, on a circumferential surface of the first insert part  37  to be inserted into the first support part  32 , for example, knurls (not depicted) are formed as a rotation-stop and slip-stop structure. 
     Next, the second straightening member  14  is described in detail with reference to, for example,  FIG. 8 ,  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13 . 
     The fastening locking part  24  of the second straightening member  14  includes, for example, a housing  54  having a rectangular cylindrical cross section, as depicted in  FIG. 8  to  FIG. 13 . The housing  54  has an insertion hole  22  penetrating to the width direction of the housing  54  and having, for example, a rectangular cross section. In this case, the housing  54  includes a lower wall surface part  56  having a through hole  56   a  in, for example, a rectangular shape. At one end and the other end of the lower wall surface part  56  in the length direction, a right wall surface part  58  and a left wall surface part  60  each having, for example, a square shape, are respectively provided to stand upright. Furthermore, between an upper end of the right wall surface part  58  and an upper end of the left wall surface part  60 , an upper wall surface part  62  having, for example, a rectangular shape, is provided to spread. Also, the upper wall surface part  62  has, on one end side in its width direction, a notched part  62   a  having a C shape in a planar view, as depicted in  FIG. 8  and  FIG. 9 . The notched part  62   a  is provided so that the lock nail part  26 , which will be described further below, is partially exposed. 
     In this fastening locking part  24 , as depicted in  FIG. 8  and  FIG. 13 , the lock nail part  26  is disposed inside the fastening locking part  24 . The lock nail part  26  is provided to extend from one end edge part to a portion near the other end edge part of the through hole  56   a  of the lower wall surface part  56  in the width direction. On one main surface (upper surface) of the lock nail part  26 , for example, three nail pieces  64 ,  66 , and  68  are disposed. The three nail pieces  64 ,  66 , and  68  each include an upright engaging surface  70  to be engaged with the upright surface  42  of the sawtooth part  40  provided on the belt part  18  of the first straightening member  12  and a tilted engaging surface  72  to be engaged with the tilted surface  44  of the sawtooth part  40 . 
     When an angle at which the upright engaging surface  70  and the tilted engaging surface  72  of the lock nail part  26  cross is taken as θ L , θ L  is set so as to be in a range of 45°&lt;θ L &lt;60°. Also, the above-described angle θ B  at which the upright surface  42  and the tilted surface  44  of the sawtooth part  40  cross and the angle θ L  at which the upright engaging surface  70  and the tilted engaging surface  72  of the lock nail part  26  cross are set to be equal. 
     Also, three nail pieces  68 ,  70 , and  72  of this lock nail part  26  are disposed so as to be in a movable state via a cantilever-like movable piece  74  with one end edge part of the through hole  56   a  of the lower wall surface part  56  in the width direction being taken as a fixed end, as depicted in  FIG. 13 . The movable piece  74  includes, for example, a hinge part  76  disposed at one end edge part of the lower wall surface part  56  in the width direction. The movable piece  74  is supported by the hinge part  76  so as to be able to freely rock to a direction orthogonal to the inserting direction of the belt part  18  of the first straightening member  12 . 
     Note in this embodiment of the invention that while the lock nail part  26  is formed of, for example, three nail pieces  64 ,  66 , and  68 , the number is not necessarily required to be three, and may be, for example, one or two, or four or more. 
     To the fastening locking part  24  of this second straightening member  14 , as depicted in  FIG. 8 ,  FIG. 10 , and  FIG. 11 , a second support part  78  for supporting the second latching part  28  is disposed. This second support part  78  is formed in, for example, a flat plate shape and in a substantially triangular shape in a planar view, and is connected to the other end side of the lower wall surface part  56  in the width direction. The second support part  78  is provided to extend outward from the other end edge part of the through hole  56   a  of the lower wall surface part  56  in the width direction. The second support part  78  is disposed in parallel with the upper wall surface part  62 . 
     The second latching part  28  is formed in a manner similar to that of the first latching part  20 . That is, the second latching part  28  includes a stem part  80 , as depicted in  FIG. 8  to  FIG. 11  and  FIG. 13 . The stem part  80  has one end side in the axial direction supported by the second support part  78  and has a hook part  82  formed on the other end side in the axial direction. 
     The fastening locking part  24 , the lock nail part  26 , and the second support part  78  of the second straightening member  14  are integrally formed of a flexible material, for example, a plastic material. 
     Also, the stem part  80  and the hook part  82  of the second latching part  28  are integrally formed of an elastic material, for example, a metal material. Furthermore, the second latching part  28  includes a second insert part  84  as depicted in  FIG. 14 , and the second insert part  84  is insert-molded by, for example, injection molding, so as to be supported by the second support part  78 . In this case, a root part side of the stem part  80  of the second latching part  28 , that is, the second insert part  84  to be inserted into the second support part  78 , is formed in, for example, a semi-circular flat shape in a planar view as a rotation-stop and slip-stop structure, as depicted in  FIG. 13 . 
     Next, the structure of fastening the belt part  18  by the first straightening member  12  and the second straightening member  14  is described in detail below with reference to  FIG. 15 ,  FIG. 16 ,  FIG. 17 ,  FIG. 18 ,  FIG. 19 , and  FIG. 20 . 
     The structure of fastening the belt part  18  by the first straightening member  12  and the second straightening member  14  is such that the belt part  18  of the first straightening member  12  is inserted into the insertion hole  22  of the fastening locking part  24  of the second straightening member  14  and the length of the belt part  18  to be pulled out from the insertion hole  22  is adjusted. 
     That is, when the belt part  18  is inserted into an entrance  22   a  of the insertion hole  22  of the fastening locking part  24  and is pulled out from an exit  22   b  of the insertion hole  22 , in particular, for example, as depicted in  FIG. 19  and  FIG. 20 , the nail pieces  64 ,  66 , and  68  of the lock nail part  26  are each engaged, by using its elastic force, mutually with any sawtooth piece  40 A among the plurality of sawtooth pieces  40 A of the sawtooth part  40  of the belt part  18  to fix the belt part  18 . With any sawtooth piece  40 A among the plurality of sawtooth pieces  40 A engaged with each of the nail pieces  64 ,  66 , and  68  of the lock nail part  26 , the fixing position of the belt part  18  in the insertion hole  22  of the fastening locking part  24  can be adjusted to set a fastening length of the belt part  18 . 
     According to the device  10  in accordance with the embodiment described above, the first latching part  20  of the first straightening member  12  is latched at one end edge of a deformed nail surface N in the width direction, and the second latching part  28  of the second straightening member  14  is latched at the other end edge of the nail surface N in the width direction. Furthermore, the free end  38 A side of the belt part  18  is inserted into the insertion hole  22  of the lock nail part  26  of the fastening locking part  24 , and the free end  38 A side of the belt part  18  is pulled, thereby allowing the belt part  18  to be fastened to the nail surface N. 
     In this case, the one end edge and the other end edge sides of the nail surface N in the width direction are pulled by the first latching part  20  and the second latching part  28 , respectively, to a direction opposite to the ingrowing direction of the deformed nail surface N, for example, “ingrown nail”. This tensile force can be increased as the length of the belt part  18  to be pulled out from the insertion hole  22  of the fastening locking part  24  is longer, that is, a length between one end part of the belt part  18  in the length direction and a portion of the belt part  18  locked by the lock nail part  26  is shorter. By contrast, this tensile force can be decreased as the length of the belt part  18  to be pulled out from the insertion hole  22  of the fastening locking part  24  is shorter, that is, the length between one end part of the belt part  18  in the length direction and the portion of the belt part  18  locked by the lock nail part  26  is longer. Therefore, this tensile force can be adjusted as appropriate in accordance with the size and shape of the deformed nail surface N, the degree of a curve of the ingrown nail, and so forth. 
     And, the tensile force adjusted by this adjustment is retained by the lock function of the lock nail part  26  inhibiting the belt part  18  from returning to the direction opposite to the inserting direction of the belt part  18 . Thus, the tensile force to the direction opposite to the ingrowing direction of the ingrown nail continuously acts at both end edges of the ingrown nail in the width direction, and a decrease in this tensile force is prevented. Therefore, according to this device  10 , deformity of the nail such as ingrown nail can be straightened. 
     Also as described above, in this device  10 , when the belt part  18  is fastened by the fastening locking part  24 , the belt part  18  makes contact with the surface of the nail surface N and pressurizes the nail surface N downward. Thus, in particular, with the belt part  18  as a center, the first latching part  20 , the fastening locking part  24 , and the second latching part  28  are each stably attached to the surface of the nail surface N without being shifted or moved. 
     Since this device  10  has the structure and operations described above, compared with the conventional technology described in, for example, Patent Literature 1, the work of twisting the coupling members by using the dedicated tool or the work of twining the coupling members when not using the dedicated tool is not required. 
     Thus, in this device  10 , burdensome efforts to attach this device  10  to the nail surface N are not required, and the attachment time is also short. Also in the conventional technology, when the work of twisting or twining the coupling members is performed, a boundary portion between a force introduction member and a coupling member may be broken by bending. By contrast, in this device  10 , these twisting work and twining work are not required, and thus inconveniences such as breakage of the device itself by bending are eliminated. 
     That is, according to this device  10 , the device can be easily attached in an effort-saving manner without damage on the device at the time of attachment, and an appropriate straightening force can be caused to act over a long period. Also, the straightening force can be caused to act as intended by the user. 
     Also, in this device  10 , the first support part  32  can stably support the first latching part  20  to the nail surface N and, furthermore, the lead part  38  can easily guide the belt part  18  to the second straightening member  14 . Also, since the sawtooth part  40  is disposed so as to be opposed to the nail surface N, when this device  10  is attached to the nail surface N, the sawtooth part  40  makes contact with the deformed nail surface N. Thus, the sawtooth part  40  can prevent a positional shift due to slipping of the belt part  18  on the nail surface N. 
     Also, in this device  10 , the upright surface  42  of the sawtooth part  40  and the upright engaging surface  70  of the lock nail part  26  are engaged together, and the tilted surface  44  of the sawtooth part  40  and the tilted engaging surface  72  of the lock nail part  26  are engaged together. Thus, when the belt part  18  is inserted into the insertion hole  22  of the fastening locking part  24 , the tilted engaging surface  72  of the lock nail part  26  is pressurized by the tilted surface  44  of the sawtooth part  40  to cause the belt part  18  to move to the inserting direction. Also, when the belt part  18  is about to return to the direction opposite to the inserting direction of the belt part  18 , the upright surface  42  of the sawtooth part  40  and the upright engaging surface  70  of the lock nail  26  part are engaged, and a surface contact is made with that engaging area. Thus, the lock function against the return force applied to the belt part  18  is firmly exerted. 
     Also, in this device  10 , one end side of the lock nail part  26  serves as a fixed end supported to the inside of the fastening locking part  24 , and the other end of the lock nail part  26  serves as a free end to allow movement. When the belt part  18  is inserted into the insertion hole  22  of the fastening locking part  24 , the tilted engaging surface  72  of the lock nail part  26  is pressurized as sliding over the tilted surface  44  of the sawtooth part  40  to be warped to the inserting direction of the belt part  18 . Thus, the belt part  18  can move through the insertion hole  22  to the inserting direction. Also, when the belt part  18  is tried to return to the direction opposite to the inserting direction of the belt part  18 , the upright surface  42  of the sawtooth part  40  and the upright engaging surface  70  of the lock nail part  26  are engaged, and a resistance force acts against the return force of the belt part  18 , thereby locking the return of the belt part  18 . 
     Furthermore, in this device  10 , when an angle at which the upright surface  42  and the tilted surface  44  of the sawtooth part  40  cross is taken as θ B , θ B  is set so that 45°&lt;θ B &lt;60°; when an angle at which the upright engaging surface  70  and the tilted engaging surface  72  of the lock nail part  26  cross is taken as θ L , θ L  is set so that 45°&lt;θ L &lt;60°; and, furthermore, it is set so that θ B =θ L . Thus, when the belt part  18  is inserted into the insertion hole  22  of the fastening locking part  24 , a tilted angle between the tilted surface  44  of the sawtooth part  40  and the tilted engaging surface  72  of the lock nail part  26  is a tilted angle suitable for the belt part  18  to move to the inserting direction. Thus, the belt part  18  can easily move to the fastening direction via the insertion hole  22  of the fastening locking part  24  and, in turn, fastening of the belt part  18  by the fastening locking part  24  onto the nail surface N is facilitated. 
     Next, one example of a method of using the nail deformity correction device  10  according to the embodiment of this invention is described in detail below with reference to  FIG. 21  to  FIG. 26 . 
       FIG. 21  is a perspective view depicting one example of a process of attaching the nail deformity correction device depicted in  FIG. 1  and  FIG. 2  to a deformed nail, and is a perspective view depicting a process of, for example, latching the first latching part of the first straightening member at one end edge of a nail in a width direction and latching the second latching part of the second straightening member at the other end edge of the nail in the width direction. 
     First, the first straightening member  12  and the second straightening member  14  are prepared, and a substantial entirety of a deformed nail surface N attached to this device is sanitized in advance as appropriate. 
     Next, the first latching part  20  of the first straightening member  12  is nipped by, for example, a needle holder (not depicted) and, as depicted in  FIG. 21 , the hook part  36  of this first latching part  20  is latched at a location of substantially one third of a nail matrix (nail root side) of a nail groove on one end edge side of the nail surface N in the width direction. The reason for this is that if the latching position of the hook part  36  of the first latching part  20  is too close to the nail matrix (nail root side), there is a fear of affecting nail formation. 
     Also, on the other end edge side of the nail surface N in the width direction, the second latching part  28  of the second straightening member  14  is latched at a location of substantially one third of the nail matrix (nail root side) of the nail groove on the other end edge side of the nail surface N in the width direction, as depicted in  FIG. 21 . 
     Next, the belt part  18  of the first straightening member  12  on its free end  38 A side is inserted into the insertion hole  22  of the fastening locking part  24  of the second straightening member  14 . In this case, the right-side constricted part  50  and the left-side constricted part  52  of the belt part  18  are nipped by hand fingers or a needle holder (not depicted) and, as depicted in  FIG. 22 , the belt part  18  is led by the lead part  38  to be inserted from the entrance  22   a  of the insertion hole  22  of the fastening locking part  24  and be pulled out from the exit  22   b  of the insertion hole  22 . 
     In this case, the pulled length of the belt part  18  pulled out from the exit  22   b  of the insertion hole  22  is adjusted, and the sawtooth part  40  of the belt part  18  is locked by the lock nail part  26  of the fastening locking part  24  at a position where a tension applies between the first latching part  20  and the second latching part  28  to cause the belt part  18  to become stretched taut. That is, the fixing position where the belt part  18  is locked is adjusted, and the fastening length of the belt part  18  with respect to the nail surface N is determined. 
     Here, as for each of the first latching part  20  and the second latching part  28 , one end edge part and the other end edge part of the nail surface N in the width direction are pulled up by any tensile force desired by the user. That is, the one end edge part and the other end edge part of the nail surface N in the width direction are pulled up by the hook part  36  of the first latching part  20  and the hook part  82  of the second latching part  28  to the direction (upward direction) opposite to, for example, the ingrowing direction of the ingrown nail. 
     The above-described tensile force can be increased as the length of the belt part  18  pulled out from the exit  22   b  of the insertion hole  22  of the fastening locking part  24  is made longer, that is, as the length between one end of the belt part  18  in the length direction and the portion of the belt part  18  locked by the lock nail part  26  is shorter, for example, as depicted in  FIG. 19 ,  FIG. 20  and  FIG. 21 , and  FIG. 22 . By contrast, this tensile force can be decreased as the length of the belt part  18  pulled out from the exit  22   b  of the insertion hole  22  of the fastening locking part  24  is made shorter, that is, as the length between one end of the belt part  18  in the length direction and the portion of the belt part  18  locked by the lock nail part  26  is longer. Therefore, this tensile force can be adjusted in accordance with the size and shape of the nail surface N of the deformed ingrown nail, the degree of the curve of the ingrown nail, and so forth. 
     After the fastening length with respect to the nail surface N of the belt part  18  is determined in this manner, the remaining portion of the belt part  18  pulled out from the exit  22   b  of the insertion hole  22  of the fastening locking part  24  is next cut out by cutting-out means  86  such as a cutter at a portion near the exit  22   b  of the insertion hole  22 , as depicted in  FIG. 23 . 
     Furthermore, in this embodiment, as depicted in  FIG. 24 , a coating material  88  such as, for example, a paste-like ultraviolet-curable resin material is applied from a container  90  such as a tube or is applied with an applying tool such as a brush (not depicted) so as to cover, for example, the fastening locking part  24 , the second support part  78 , a boundary part between the second support part  78  and the second latching part  78 , and its surroundings of the second straightening member  14 , thereby forming an application part  92 . Also, similarly, an application part  94  can be formed as appropriate at a boundary part between the first latching part  20  and the first support part  32  of the first straightening member  12 . 
     Then, the entirety of each of the application parts  92  and  94  is irradiated with ultraviolet rays by, for example, an ultraviolet LED (ultraviolet light-emitting diode), for a predetermined time, for example, on the order of twenty seconds, as depicted in  FIG. 25 . This cures the application parts  92  and  94 , and coated parts  96  and  98  are formed, respectively, as depicted in  FIG. 26 . The coated part  96  protects the fastening locking part  24 , the second support part  78 , the boundary part between the second support part  78  and the second latching part  78 , and its surroundings. Also, the coated part  98  protects the boundary part between the first latching part  20  and the first support part  32  of the first straightening member  12  and its surrounding. Furthermore, the coated parts  96  and  98  have a function of stably maintaining the tensile force of pulling the one end edge part and the other end edge part of the nail surface N in the width direction upward. 
       FIG. 27  is a perspective view depicting a modification example of the second straightening member that can be applied to the nail deformity correction device according to the present invention.  FIG. 28  is a plan view of the second straightening member depicted in  FIG. 27 .  FIG. 29  is a perspective view depicting a second insert part of a second latching part depicted in  FIG. 27  and  FIG. 28 . 
     In this modification example, compared with the device  10  according to the embodiment described above, in particular, the shape of a second insert part  85  of the second latching part  28  is different. That is, while the second insert part  84  of the second latching part  28  is formed in, for example, a semi-circular flat shape in a planar view in the above-described embodiment, the second insert part  85  of the second latching part  88  in the second straightening member  14  according to the modification example depicted in  FIG. 27  and  FIG. 28  is formed in, for example, a rectangular shape in a planar view. 
       FIG. 30  depicts another example of the embodiment of the nail deformity correction device according to the present invention, and is a perspective view depicting one example of a process of attaching a first straightening member and a second straightening member of the nail deformity correction device to a deformed nail.  FIG. 31  is perspective view depicting one example of the second straightening member to be applied to the nail deformity correction device depicted in  FIG. 30 .  FIG. 32(A)  is a sectional view depicting a state when the first straightening member is inserted into the second straightening member depicted in  FIG. 30  and  FIG. 32(B)  is an enlarged view of an E part of  FIG. 32(A) . Furthermore,  FIG. 33  is a sectional view of an operation state of releasing an engaged state between a sawtooth part of the first straightening member and a lock nail part of the second straightening member from the state depicted in  FIG. 32 . 
     The device  100  according to this embodiment is different, in particular, in the structure of the fastening locking part  24  of the second straightening member  14 , compared with the device  10  described above. In the following, different points compared with the device  10  are mainly described. Also, among reference signs written in the drawings of  FIG. 30  to  FIG. 33 , members with same reference signs used in the description of the device  10  according to the embodiments described above have similar structure, operation, and effect, and therefore detailed description of these members are omitted. 
     That is, in the second straightening member  14  of the device  100  according to this embodiment, the fastening locking part  24  of the second straightening member  14  includes, as depicted in  FIG. 30  and  FIG. 31 , the housing  54  having, for example, a rectangular cylindrical cross section. The housing  54  has the insertion hole  22  penetrating to the width direction of the housing  54  and having, for example, a rectangular cross section. The housing  54  includes a lower wall surface part  102  having, for example, a rectangular shape. At one end and the other end of the lower wall surface part  102  in the longitudinal direction, a right wall surface part  104  and a left wall surface part  106  each having, for example, a rectangular shape, are respectively provided to stand upright. Furthermore, between an upper end of the right wall surface part  104  and an upper end of the left wall surface part  106 , an upper wall surface part  108  having, for example, a rectangular shape, is provided to spread. The upper wall surface part  108  has a notched part  108   a  having a U shape in a planar view as depicted in  FIG. 31 . The notched part  108   a  is provided from one end side to the other end side of the upper wall surface part  108  in the width direction and has a predetermined length at an intermediate part of the upper wall surface part  108  in the longitudinal direction. This notched part  108   a  is provided so that a lock nail part  110 , which will be described further below, is partially exposed. 
     In the fastening locking part  24 , as depicted in  FIG. 31  and  FIG. 32 , the lock nail part  110  is disposed inside the fastening locking part  24 . The lock nail part  110  includes a surrounding portion  112  surrounded by the notched part  108   a  of the upper wall surface part  108 . The surrounding portion  112  is connected to one end of the upper wall surface  108  in the width direction. The surrounding portion  112  has the one end in the width direction as a fixed end and the other end in the width direction as a free end. Thus, the free end side of the surrounding portion  112  is formed so as to freely rock in a vertical direction. In this case, the fixed end side of the surrounding portion  112  includes a hinge part  114 . By the hinge part  114 , the free end side can freely lock. 
     In the lock nail part  110 , on a lower surface of the surrounding portion  112  opposed to the lower wall surface part  102 , for example, one nail piece  116  is disposed. 
     The nail piece  116  each includes an upright engaging surface  118  to be engaged with the upright surface  42  of the sawtooth part  40  provided to the belt part  18  of the first straightening member  12  and a tilted engaging surface  120  to be engaged with the tilted surface  44  of the sawtooth part  40 . In the device  100  of this embodiment, compared with the device  10  of the embodiment described above, the sawtooth part  40  included in the belt part  18  of the first straightening member  12  is formed on the other main surface (upper surface) of the belt part main body  30 . 
     In this case, when an angle at which the upright engaging surface  118  and the tilted engaging surface  120  of the nail piece  116  cross is taken as θ L , as with the device  10  of the embodiment described above, θ L  is set so as to be in a range of 45°&lt;θ L &lt;60°. Also, the above-described angle θ B  at which the upright surface  42  and the tilted surface  44  of the sawtooth part  40  cross and the angle θ L  at which the upright engaging surface  118  and the tilted engaging surface  120  of the nail piece  116  cross are set to be equal. 
     The nail piece  116  of this lock nail part  110  has a structure of the above-described surrounding portion  112  as depicted in  FIG. 32(B)  and is thus formed in a cantilever manner such that, with the one end of the upper wall surface part  108  in the width direction as a fixed end, its free end side is in a movable state. That is, the lock nail part  10  is supported by the hinge part  114  so as to freely rock to a direction orthogonal to the inserting direction of the belt part  18  of the first straightening member  12  inserted into the insertion hole  22  of the fastening locking part  24 . 
     Furthermore, the fastening locking part  24  further includes an activation piece  122  connected to the lock nail part  110  and exposed to outside the fastening locking part  24 . The activation piece  122  includes a neck part  124 A having a rectangular cross section, as depicted in  FIG. 31  and  FIG. 32(B) . A lower end part of the neck part  124 A is connected to the nail piece  116  of the lock nail part  110 , and a side end surface of the neck part  124 A is connected to the end surface of the upright engaging surface of the nail piece  116  so as to be flush therewith. Also, at an upper end of the neck part  124 A, a knob part  124 B having, for example, a spherical crown shape, is connected. In this case, the lock nail part  110  and the activation piece  122  are integrally formed. 
     In this embodiment, as depicted in  FIG. 31  and  FIG. 32(A) , a second support part  126  is formed in a flat plate shape having, for example, a substantially narrowly-elongated rectangular shape in a planar view, and is connected to the other end side of the lower wall surface part  102  in the width direction. The second support part  126  is disposed in parallel with the upper wall surface part  108 . Also, a second latching part  128  does not have the stem part  80  compared with the second latching part  28  of the device  10  described above, and is formed of only a hook part  130 . Furthermore, the second latching part  128  includes a second insert part  136  having, for example, a stem shape, compared with the second insert part  84  of the device  10  described above, and the second insert part  136  is insert-molded by, for example, injection molding, so as to be supported by the second support part  126 . In this case, in a root part side of the hook part  130  of the second latching part  128 , that is, in the second insert part  136  to be inserted into the second support part  126 , for example, knurls (not depicted) are formed as a rotation-stop and slip-stop structure on the periphery of the insert part  136 , as depicted in  FIG. 32(A) . 
     Note that a first latching part  132  is formed of only the hook part  134  identical in shape and size to the hook part  130  of the second latching part  128 . Also, the first latching part  132  is not provided with a first support part dish, compared with the second latching part  28  of the device  10  described above, and the first latching part  132  is disposed at one end of the belt part  18  in the length direction. In this case, the first latching part  132  includes a first insert part  138  having a stem shape, and the first insert part  138  is insert-molded by, for example, injection molding, so as to be supported by one end of the belt part  18  in the length direction. 
     In this embodiment, the fastening locking part  24 , the lock nail part  110 , and the second support part  126  are integrally formed of a flexible material, for example, a plastic material. Also, the hook part  130  and the insert part  136  of the second latching part  128  are integrally formed of an elastic material, for example, a metal material. Similarly, the hook part  134  and the insert part  138  of the first latching part  132  are integrally formed of an elastic material, for example, a metal material. 
     According to the device  100  in accordance with the embodiment depicted in  FIG. 30  to  FIG. 33 , the activation piece  122  can pull up the lock nail part  110  to a direction orthogonal to the inserting direction of the belt part  18  and isolating the engagement between the sawtooth piece  40 A of the sawtooth part  40  and the nail piece  116  of the lock nail part  110 . In this case, a knob part  124 B of the activation piece  122  is nipped or the like by hand fingers or a needle holder (not depicted), thereby allowing the lock nail part  110  to be pulled upward, as depicted in  FIG. 33 . Thus, the engaged state between the upright surface  42  of the sawtooth piece  40 A of the sawtooth part  40  and the upright engaging surface  118  of the lock nail part  110  and the engaged state between the tilted surface  44  of the sawtooth piece  40 A of the sawtooth part  40  and the tilted engaging surface  120  of the lock nail part  110  can be released. 
     Therefore, in the device  100  in accordance with this embodiment, the belt part  18  can be moved to a direction opposite to the inserting direction of the belt part  18 . Thus, even after the device  100  is attached to the nail surface N, the belt part  18  is moved as appropriate from the insertion hole  22  of the fastening locking part  24  to the direction opposite to the inserting direction to once loosen fastening of the belt part  18  and adjust the strength of fastening, thereby allowing the straightening force applied to the nail surface N to be freely and easily changed. Furthermore, according to this device  100 , the belt part  18  can be pulled out from the insertion hole  22  of the fastening locking part  24  for reuse of the first straightening member  12  once used. 
       FIG. 34  depicts a modification example of the second straightening member depicted in  FIG. 30  and  FIG. 31  and is an enlarged sectional view of main parts depicting a state in which the first straightening member is inserted into the second straightening member. In this modification example, compared with the second straightening member  14  according to the device  100  of the above-described embodiment, in particular, the number of nail pieces of the lock nail part  110  is different. 
     That is, in the lock nail part  110  according to the device  100  depicted in  FIG. 30  to  FIG. 33 , for example, only one nail piece  116  is provided. In the second straightening member  14  of this modification example, the lock nail part  110  includes, for example, three nail pieces  140   a,    140   b,  and  140   c.  Also, the number of nail pieces of this lock nail part  110  may be, for example, two or four or more. 
       FIG. 35  depicts still another example of the embodiment of the nail deformity correction device according to the present invention and is a sectional view depicting a state in which the first straightening member of the nail deformity correction device is inserted into the second straightening member. 
     A device  150  according to this embodiment is different, in particular, in the structure of a fastening locking part of the second straightening member, compared with the device  10  and the device  100  according to the embodiments described above. In the following, different points compared with the device  10  and the device  100  are mainly described. Also, among reference signs written in the drawing of  FIG. 35 , members with same reference signs used in the description of the device  10  and the device  100  according to the embodiments described above have similar structure, operation, and effect, and therefore detailed description of these members are omitted. 
     That is, in the device  150  according to this embodiment, as depicted in  FIG. 35 , it is characterized in that, in particular, the fastening locking part  24  of the second straightening member  14  includes a lock nail part  152  formed of a single nail piece  154  and the first straightening member  12  includes concave/convex part  156  to be locked to the nail piece  154  of the lock nail part  152 . 
     The lock nail part  152  of the fastening locking part  24  according to this device  150  includes the nail piece  154  formed of, for example, a stem-shaped part. This nail piece  154  can be formed to have its sectional shape being a circular shape, rectangular shape, square shape, oval shape, or any other shape. 
     On the other hand, on the belt part  18  of the first straightening member  12 , a serration part  156  to be locked to the nail piece  154  of the lock nail part  152  is disposed. In this case, the serration part  156  is characterized to include, as depicted in  FIG. 35 , a plurality of concave parts  158   a  and convex parts  158   b  consecutively provided. 
     According to the device  150  in accordance with the embodiment depicted in  FIG. 35 , the activation piece  122  can pull up the lock nail part  152  to a direction orthogonal to the inserting direction of the belt part  18  and releasing a locked state between the concave part  156   a  and the convex part  156   b  of the serration part  156  and the nail pieces  154  of the lock nail part  152 . That is, the knob part  124 B of the activation piece  122  is nipped or the like by, for example, hand fingers or a needle holder (not depicted) to pull the lock nail part  152  upward. Thus, the nail piece  154  of the lock nail part  152  can be isolated from the concave parts  156   a  of the serration part  156 . 
     Therefore, in the device  150  according to this embodiment, the belt part  18  can be moved to a direction opposite to the inserting direction of the belt part  18 . Thus, even after the device  150  is attached to the nail surface N, the belt part  18  is moved as appropriate from the insertion hole  22  of the fastening locking part  24  to the direction opposite to the inserting direction to once loosen fastening of the belt part  18  and adjust the strength of fastening, thereby allowing the straightening force applied to the nail surface N to be freely and easily changed. Furthermore, according to this device  150 , the belt part  18  can be pulled out from the insertion hole  22  of the fastening locking part  24  for reuse of the first straightening member  12  once used. 
     REFERENCE SIGNS LIST 
       10  nail deformity correction device 
       12  first straightening member 
       14  second straightening member 
       16  serration part 
       18  belt part 
       20  first latching part 
       22  insertion hole 
       24  fastening locking part 
       26  lock nail part 
       28  second latching part 
       30  belt part main body 
       32  first support part 
       34  stem part 
       36  hook part 
       37  first insert part 
       38  lead part 
       38 A free end 
       40  sawtooth part 
       40 A sawtooth piece 
       42  upright surface 
       44  tilted surface 
       46  right side wall part 
       48  left side wall part 
       50  right-side constricted part 
       52  left-side constricted part 
       54  housing 
       56  lower wall surface part 
       58  right side wall surface part 
       60  left side wall surface part 
       62  upper wall surface part 
       62   a  notched part 
       64 ,  66 ,  68  nail piece 
       70  upright engaging surface 
       72  tilted engaging surface 
       74  movable piece 
       76  hinge part 
       78  second support part 
       80  stem part 
       82  hook part 
       84 ,  85  second insert part 
       86  cutting-out means 
       88  coating material 
       90  container 
       92 ,  94  application part 
       96 ,  98  coated part 
       100  nail deformity correction device 
       102  lower wall surface part 
       104  right side wall surface part 
       106  left side wall surface part 
       108  upper wall surface part 
       110  lock nail part 
       112  surrounding portion 
       114  hinge part 
       116  nail piece 
       118  upright engaging surface 
       120  tilted engaging surface 
       122  activation piece 
       124 A neck part 
       124 B knob part 
       126  second support part 
       128  second latching part 
       130 ,  134  hook part 
       132  first latching part 
       136  first insert part 
       138  second insert part 
       142 ,  144 ,  146  nail piece 
       150  nail deformity correction device 
       152  lock nail part 
       154  nail piece 
       156  concave/convex part 
       158   a  concave part 
       158   b  convex part 
     N nail surface of a deformed nail