Buckle

A buckle with an enhanced efficiency in removing a foreign substance is provided. The buckle includes: a plug; and a socket provided with an insertion opening into which the plug is to be inserted. The socket includes: a pair of front pieces disposed side by side in a width direction intersecting with an insertion direction of the plug; a back piece disposed to face each of the front pieces; and a bottom piece that connects each of the front pieces and the back piece. A slit defined between the pair of front pieces extends in the insertion direction from the insertion opening across the bottom piece and the front pieces of the socket. Due to the presence of the slit, a cross section of the socket intersecting with the insertion direction is in a C-shape.

This application is a national stage application of PCT/JP2012/063534, which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a buckle that fastens belts to each other or a belt to a different article. In particular, the present invention relates to a side release buckle including a pair of lock arms.

BACKGROUND ART

Typically, a buckle including a plug and a socket that are detachably connectable to each other is used in various use applications to fasten string members of belts or the like to each other or to fasten a belt or the like to a different article such as a bag body.

Such a buckle should be capable of being easily attached/detached and being reliably kept in a connected state (i.e., the basic functions of the buckle) and, further, is desired to be improved in a guiding function required during a connecting operation and be reduced in overall weight.

A buckle disclosed in Patent Literature 1 is a side release buckle that basically includes a plug and socket, each of which includes a belt attachment. The plug also includes a pair of lock arms provided with engagement portions, which are engaged with the socket at an inside of the socket, so that the plug is connected to the socket.

The socket also includes a body in the form of a hollow cylinder. The body has a plug-opposed end provided with an insertion opening and lateral sides each provided with an operation opening. The lock arms of the plug are inserted into the socket through the insertion opening and the engagement portions are engaged. The lock arms are partially exposed from the operation opening in a connected state so that a user can clasp the exposed parts of the lock arms and move them to disengage the engagement portions.

In particular, the buckle disclosed in Patent Literature 1 includes a guide bar disposed between the pair of lock arms of the plug to stabilize a posture of the plug (i.e., improve the guiding function) during the insertion of the plug into the socket.

The guide bar is to be received in the socket. Alternatively, a socket body of the socket may be provided with a V-shaped or Y-shaped cut formed in conformity with the guide bar so that the guide bar of the plug is fitted in the cut of the socket when the plug is connected to the socket. Such a cut of the socket contributes to preventing an increase in a thickness of the buckle and reducing a weight of the buckle.

A bucket disclosed in Patent Literature 2 includes a guiding arrangement provided to an internal surface of a socket to ensure the guiding function. Further, the buckle has two small-sized guide bars and enlarged cuts in the socket body, thereby further reducing the weight of the buckle.

CITATION LIST

SUMMARY OF THE INVENTION

Problem(s) to be Solved by the Invention

As described above, the socket of the typical buckle is provided with the cut to reduce the weight of the buckle.

The cut of the socket has been found helpful in removing a foreign substance entering the socket.

However, while increasing an area where an inner space of the cavity is in communication with the outside of the buckle, the cut, the operation opening and the insertion opening fail to sufficiently improve the typical buckle in terms of efficiency in removing a foreign substance.

Specifically, the socket of the typical buckle is in a cylindrical shape basically continuous in a plug-insertion direction and has a cross section partially annularly continuous. Incidentally, since the typical buckle is to be attached to a belt or the like and is accordingly shaped flat, the socket is in a flat cylindrical shape.

Specifically, the socket body includes: a plate-shaped front piece; a plate-shaped back piece opposed to the front piece; and lateral pieces that connect the front and back pieces into a flat cylindrical shape. The cylindrical socket body has a first end provided with an opening serving as the insertion opening and a second end that is opposite to the first end and provided with a bottom plate as needed. The bottom plate is provided with a drain port as needed. The operation opening is provided in a middle of each of the lateral surfaces and is widened by cutting the front and back pieces as needed.

The above cut for weight reduction is provided to each or one of the front and back pieces to be continuous from the insertion opening or the bottom plate. It should be noted that it is necessary for defining the cylindrical shape that the front piece and the back piece be connected to each other by the opposite pair of lateral pieces so that the socket body partially has an annular cross section.

However, due to the necessity of such a basic arrangement of the socket, efficiency in removing a foreign substance entering the socket cannot be enhanced even when the cut is widened to the front or back piece.

An object of the invention is to provide a buckle provided with an enhanced efficiency in removing a foreign substance.

Means for Solving the Problem(s)

According to an aspect of the invention, a buckle includes: a plug; and a socket provided with an insertion opening into which the plug is to be inserted, the socket including: a pair of front pieces disposed side by side in a width direction intersecting with an insertion direction of the plug; a back piece disposed to face each of the front pieces; and a bottom piece disposed opposite to the insertion opening to connect the front pieces and the back piece, in which a slit is defined between the pair of front pieces, and the slit extends in the insertion direction from the insertion opening across the bottom piece and the front pieces of the socket.

In the above aspect, the socket is provided with the slit on a side where the front pieces are provided and the slit extends in the insertion direction longitudinally across the socket. The slit thus serves to enhance efficiency in removing a foreign substance.

For instance, when a foreign substance enters the socket through the insertion opening while the plug and the socket are disconnected, the foreign substance may be swept out of the socket along the slit over the entire length in the insertion direction with a finger or a stick inserted in the slit.

A typical cylindrical socket is not provided with such a slit extending along the entire length in the insertion direction, so that a foreign substance should be swept out in a restricted manner. In contrast, the socket according to the above aspect is provided with the slit extending along the entire length in the insertion direction, so that a foreign substance can be easily and reliably swept out of the entire socket.

Further, in the above aspect, due to the presence of the slit extending along the entire length in the insertion direction, the socket may be shortened in the insertion direction and the plug may accordingly be shortened, thereby further reducing the weight and the size of the buckle.

In the above aspect, it is preferable that the plug include: a base; and a pair of lock arms that extend in the insertion direction from the base and each include an engagement portion, the socket define a cavity provided between the front pieces and the back piece and configured to receive the lock arms therein, and the socket further include engaged portions provided to the front pieces and the back piece, the engaged portions each being engageable with the engagement portion.

In the above aspect, the pair of lock arms can thus be received in the cavity between the front pieces and the back piece. Therefore, the invention is suitably applicable to a side release buckle including a pair of lock arms.

In the above aspect, it is preferable that the socket further include at least a pair of lateral pieces provided to opposite sides of the socket defined in the width direction to connect the front pieces and the back piece, the lateral pieces being continuous in the insertion direction.

In the above aspect, the lateral pieces on opposite lateral sides thus serve to reliably connect the front pieces to the back piece. Further, the socket, which includes the front pieces, the back piece and the lateral pieces, has a C-shaped cross section at any position defined in the insertion direction, the C-shaped cross section intersecting with the insertion direction of the socket. Therefore, the plug can be inserted without any interference and a foreign substance can be reliably swept through the slit.

In the above aspect, it is preferable that the bottom piece be provided with a cut that is continuous with the slit, and the cut divide the bottom piece in the width direction into two parts, the two parts being connected to each other by a portion erected from the back piece.

In the above aspect, the bottom piece of the socket has a side near the back piece and including a portion erected from the back piece. The erected portion is in the form of a rib continuous in the width direction of the socket along the back piece.

For instance, when the bottom piece is provided along the entire length in the width direction of the socket and a side of the bottom piece near the front pieces is provided with a cut continuous with the slit to halve the bottom piece, a portion not removed to form the cut is in the form of the rib erected from the bottom piece. The front pieces provided side by side to the socket and the halved bottom piece are connected to one another by the portion in the form of the rib and the bottom piece, which are disposed in mutually intersecting direction to enhance the rigidity of a connecting arrangement (i.e., the rigidity of the bottom piece of the socket).

In the above aspect, it is preferable that the plug further include a guide bar that extends in the insertion direction, and the front pieces each have a peripheral portion that faces the slit to function as a guide abutting against the guide bar.

In the above aspect, the peripheral portion of each of the front pieces thus also functions as a guiding arrangement during insertion of the plug without necessitating any other guiding arrangement or the like, which results in further simplification of the structure of the socket and reduction in the weight of the socket.

In the above aspect, it is preferable that the peripheral portion of each of the front pieces be flared toward the insertion opening.

In the above aspect, the plug can thus be easily inserted through the insertion opening due to a favorable guiding function.

In the above aspect, it is preferable that when the guide bar is received in the slit, a surface of the guide bar define a continuous surface in combination with a surface of each of the front pieces.

In the above aspect, while providing the guiding function as described above, the guide bar closes the slit when the plug and the socket are connected to improve the appearance of the buckle.

In the above aspect, it is preferable a step to be engaged with the peripheral portion of each of the front pieces be provided to a peripheral portion of the surface of the guide bar.

In the above aspect, while the guide bar provides the guiding function to connect the plug and the socket as described above, the step of the guide bar is fitted on the peripheral portion of each of the front pieces defined along the slit when the plug and the socket are connected. Therefore, for instance, when an external force such as a bending force acts between the plug and the socket, the mutually fitted step and peripheral portion exhibit resistivity to such an external force to enhance a bending rigidity, thereby effectively preventing the buckle from being accidentally unlocked.

According to another aspect of the invention, a buckle includes: a plug; and a socket provided with an insertion opening into which the plug is to be inserted and a slit that extends in an insertion direction of the plug longitudinally across the socket, in which a cross section of the socket intersecting with the insertion direction is in a C-shape.

In the above aspect, the socket (i.e., a socket body excluding a belt attachment and the like) is provided with the slit extending longitudinally thereacross, so that a cross section of the socket is not in a cylindrical shape but is in a C-shape. As a result, the above advantageous effects of the invention attributed to the C-shaped cross section can be achieved.

DESCRIPTION OF EMBODIMENT(S)

As shown inFIG. 1, a side release buckle1according to the exemplary embodiment includes a plug10and a socket20into which the plug10is to be inserted to be engaged.

The side release buckle1according to the exemplary embodiment is configured to fasten/unfasten a pair of belt ends (e.g., ends of different belts or both ends of a single belt) and the plug10and the socket20respectively include belt attachments19,29.

In the exemplary embodiment, the plug10and the socket20are each integrally formed from a synthetic resin by injection molding. Incidentally, the plug10and the socket20may be formed not from a synthetic resin but from any other material such as metal, and the injection molding may be replaced by any other molding method.

The plug10will be described below with reference toFIGS. 1 and 2.

The plug10includes a base11having a first end provided with the belt attachment19and a second end provided with a pair of lock arms12and a guide bar13, and the lock arms12are each provided with an engagement portion18in the form of a protrusion.

In the exemplary embodiment, the lock arms12and the guide bar13are configured to be inserted into the socket20and a direction in which the lock arms12and the guide bar13extend is defined as an insertion direction of the plug10. Similarly, a direction in which the lock arms12are arranged side by side is defined as a width direction of the plug10, and a direction intersecting with the insertion direction and the width direction is defined as a thickness direction of the plug10.

The belt attachment19provided to the first end of the base11has a belt-insertion hole and an attachment bar. A belt is inserted into the belt-insertion hole and wound around the attachment bar to be secured by a predetermined position thereof.

The engagement portions18protrude from distal ends of the lock arms12in the thickness direction of the plug10, so that the distal ends of the lock arms12are in a T-shape when seen from a lateral side (seeFIG. 2(B)).

When the lock arms12are inserted into the socket20, the engagement portions18are engaged with engaged portions28provided inside the socket20(seeFIGS. 3 to 6, described later in detail) to maintain the connection of the plug10and the socket20.

The lock arms12extend side by side from the base11in the insertion direction and each have an elastically deformable portion defined from a middle portion to the distal end. The respective elastically deformable portions of the lock arms12are thus movable in the width direction(s) toward/away from each other.

Further, the lock arms12are widened from the middle portions toward the distal ends while being slightly curved to be closer to each other toward the distal ends. Therefore, for instance, when a user clasps the middle portions or the engagement portions18at the distal ends are guided in the socket20, thereby applying a force to move the lock arms12closer to each other, a narrow portion of each of the lock arms12near the base11is mainly bent even though the force causing elastic deformation is received by each of the lock arms12as a whole.

The guide bar13extends between the pair of lock arms12from the base11in the insertion direction.

The guide bar13is in a Y-shape as a whole. A portion of the guide bar13toward the base11is branched into a pair of branch portions131respectively connected to lateral portions of the base11.

An opening132that penetrates the plug10from a front surface (seeFIG. 2(A)) to a back surface (seeFIG. 2(C)) of the plug10is defined by the pair of branch portions131and the base11.

As shown inFIGS. 2(A) and 2(C), the guide bar13has a pair of lateral surfaces each being in an arc along the entire length. Specifically, while extending along the insertion direction of the plug10in the vicinity of a distal end of the guide bar13(i.e., at a position remote from the base11), the pair of lateral surfaces extend outward in the width direction to be spaced from each other toward the base11. A contour of the guide bar13is thus in a flared shape as a whole.

Each of the outer lateral surfaces of the guide bar13in an arc is provided with a protrusion133formed along a continuing direction of the lateral surface.

As shown inFIG. 2(B), the protrusion133has a back surface with a peripheral portion aligned with a back surface of the guide bar13. In contrast, the protrusion133has a front surface disposed with a predetermined space from a peripheral portion of a front surface of the guide bar13. In other words, the front surface of the protrusion133is present at a level lower than that of the front surface of the guide bar13. A step134is thus defined continuous along the peripheral portion of the front surface of the guide bar13.

The front surface of the guide bar13is mostly continuous at the same level as that of the base11. The front surface of the guide bar13has a distal end provided with a slant137(seeFIGS. 2(A) and 2(B)).

In contrast, a portion of the back surface of the guide bar13toward the base11is continuous with a back surface of the base11and a portion toward the distal end of the guide bar13(i.e., a portion remote from the base11) recedes in the thickness direction from the back surface of the base11to define a step135between the back surface of the guide bar13and the back surface of the base11(seeFIG. 2(B)).

The step135of the back surface of the guide bar13is defined along a peripheral portion of the opening132. Further, the portion of the back surface of the guide bar13toward the distal end of the guide bar13is provided with a concave136(see2(C)).

The socket20will be described below with reference toFIGS. 1 and 3 to 6.

The socket20includes a body21into which the lock arms12and the guide bar13of the plug10are to be inserted. The body21has a first end provided with an insertion opening201into which the lock arms12and the guide bar13are to be inserted and a second end provided with the belt attachment29.

In regard to the socket20and the body21according to the exemplary embodiment, a direction in which the lock arms12and the guide bar13are inserted is defined as an insertion direction, a direction in which the lock arms12are arranged side by side is defined as a width direction, and a direction intersecting with the insertion direction and the width direction is defined as a thickness direction.

The body21includes a pair of front pieces22defining a front surface of the body21and a back piece23defining a back surface of the body21, the front pieces22and the back piece23facing each other with a predetermined space.

The front pieces22are each in the shape of a belt that extends in the insertion direction along both lateral sides of the body21and define a front exterior surface of the body21.

The back piece23is in the shape of a plate that extends in the insertion direction and the width direction and defines a back exterior surface of the body21.

A cavity202is defined between the front pieces22and the back piece23to be in communication with the insertion opening201, so that the lock arms12can be received in the cavity202when inserted through the insertion opening201to connect the plug10and the socket20to each other (seeFIGS. 8 to 10orFIG. 12).

The front pieces22are each connected to a lateral edge of the back piece23by two lateral pieces24,25(i.e., a pair of lateral pieces24are disposed toward the insertion opening201and a pair of lateral pieces25are disposed toward the belt attachment29). A peripheral portion of each of the front pieces22toward the belt attachment29is connected to the back piece23via a bottom piece26.

A slant227is provided between each of the front pieces22and the bottom piece26(seeFIG. 3(A)andFIG. 1). The slant227is the same in length and inclination as the slant137of the distal end of the guide bar13of the plug10.

The lateral pieces24,25are each continuous along the insertion direction and the bottom piece26is continuous along the width direction. Each of the lateral pieces24,25and the bottom piece26are thus disposed in mutually intersecting directions.

The front pieces22and the back piece23are thus connected by the lateral pieces24,25and the bottom piece26disposed in the mutually intersecting directions, thereby ensuring the rigidity of the body21including the front pieces22, the back piece23, the lateral pieces24,25and the bottom piece26.

Operation openings203are provided between the lateral pieces24,25.

The operation openings203, which are in communication with the cavity202, allow the middle portions of the lock arms12inserted in the cavity202to be exposed when the plug10and the socket20are connected (FIGS. 8 to 10orFIG. 12). The operation openings203allow the lock arm12to be externally accessible to be disengaged.

It should be noted that the operation openings203, which are opened between the lateral pieces24,25(i.e., on lateral surfaces of the body21), are formed such that the front pieces22and the back piece23recede in a curve to allow a user to easily disengage the lock arms12.

A slit204is provided between the pair of front pieces22(seeFIG. 3(A)andFIG. 1).

The body21includes the pair of front pieces22and the back piece23that are continuous via the laterals pieces24,25, the front pieces22being separated from each other by the slit204. Therefore, the body21has a C-shaped cross section at any position along the entire length of the body21in the insertion direction, the C-shaped cross section intersecting with the insertion direction (seeFIGS. 5 and 6).

The slit204extends in the insertion direction from the insertion opening201to the bottom piece26.

The bottom piece26is provided with a cut261receding from the front surface toward the back surface of the bottom piece. The cut261is continuous with the slit204, so that an inner space of the body21is in communication with the outside of the body21through a large continuous opening that extends from the insertion opening201via the slit204to the cut261.

It should be noted that the cut261does not reach the back surface of the bottom piece26and thus the bottom piece26is partially left as a rib262, which is erected from the back piece23(FIG. 3(A)andFIGS. 4 to 6).

Due to the presence of the rib262, two parts of the bottom piece26, which are separated from each other by the cut261, are connected by the rib262so that the bottom piece26is in the form of a plate continuous along the entire length of the body21in the width direction. The bottom piece26and the back piece23thus intersect with each other along the entire length of the body11in the width direction, which results in ensuring the rigidity of the back piece23and thus the rigidity of the body21.

The engaged portions28corresponding to the engagement portions18of the plug10are arranged in two pairs (i.e., four in total) inside the body21.

Specifically, as shown inFIG. 3(C)andFIGS. 4 to 6, a first pair of engaged portions28are arranged at two opposite positions on interior surfaces of the front pieces22and a second pair of the engaged portions28are arranged at two opposite positions on an interior surface of the back piece23. The engaged portions28, each of which include a stepped surface opposed to the bottom piece26, are engaged with the pair of engagement portions18provided to the distal ends of the lock arms12to restrict the lock arms12from displacing (i.e., coming off) toward the insertion opening201.

Incidentally, the back piece23is provided with through holes281penetrating therethrough and the engaged portions28of the back piece23are defined by interior surfaces of the through holes281toward the insertion opening201.

As shown inFIG. 3(B)andFIGS. 4 to 6, guide members223,233are respectively provided to the interior surfaces of the front pieces22and the back piece23, the guide members223,233being disposed toward the insertion opening201relative to the engaged portions28.

When the lock arms12are inserted through the insertion opening201to connect the plug10and the socket20, the guide members223,233serve to guide the engagement portions18at the distal ends of the lock arms12so that the pair of lock arms12are squeezed to approach each other and thus the engagement portions18are engaged with the engaged portion28.

As shown inFIG. 3(A), the front pieces22each have a peripheral portion221facing the slit204. The peripheral portion221extends in the insertion direction near the bottom piece26, and is curved in the width direction to approach the lateral pieces24toward the insertion opening201. The peripheral portion221is thus in the shape of an arc protruding toward the slit204as a whole.

As shown inFIGS. 4 to 6, the interior surface of the back piece23is provided with guiding steps231continuously extending to the lateral pieces24in the form of peripheral portions in conformity with the contour of the insertion opening201. The guiding steps231are each in the same arc shape as that of the peripheral portion221of each of the front pieces22.

When the guide bar13is inserted through the insertion opening201to connect the plug10and the socket20, the guide bar13is guided by the peripheral portions221and the guiding steps231to be received in an area between the peripheral portions221and the guiding steps231.

An interrelation of the plug10and the socket20will be described with reference toFIGS. 7 to 10.

In the exemplary embodiment, the plug10and the socket20are brought opposite to each other as shown inFIG. 7and then the plug10is inserted into the socket20to be connected as shown inFIGS. 8 to 10.

As shown inFIG. 7, a dimension of the base11of the plug10in the thickness direction is the same as a dimension of the body21of the socket20in the thickness direction (a dimension from an exterior surface of each of the front pieces22to an exterior surface of the back piece23).

In the front surface of the guide bar13of the plug10, a portion provided with the step134continuous from the distal end of the guide bar13to the branch portion131is the most thickened and an upper edge of this portion is evenly flush with a front surface of the base11.

In contrast, due to the presence of the step135between the back surface of the guide bar13and the back surface of the base11, the back surface of the guide bar13recedes from the back surface of the base11.

As shown inFIGS. 7 and 8, when the guide bar13is inserted into the socket20through the insertion opening201, the front surface of the guide bar13is guided by the pair of peripheral portions221and the back surface of guide bar13is guided by the guiding step231so that the guide bar13is received in the slit204.

As shown inFIGS. 9 and 6, the front surface of the guide bar13is received in the slit204to close the slit204.

Specifically, the front surface of the guide bar13and the exterior surface of each of the front pieces22are disposed at the same level to in combination define a continuous surface. Simultaneously, the peripheral portion221of each of the front pieces22is received on the step134of the front surface of the guide bar13and the protrusion133is received in the cavity202below the front pieces22(see a dotted line inFIG. 9). Specifically, an edge of the peripheral portion221abuts against a lateral surface of the guide bar13(i.e., a portion defined as the step134and absent of the protrusion133), an interior surface (back surface) of the peripheral portion221abuts against a narrow front surface of the protrusion133(see a chain line inFIG. 6).

The guide bar13and each of the front pieces22are thus engaged with each other both in the insertion direction and in the thickness direction to be mutually restricted from displacement.

Further, when the guide bar13is received in the slit204, the slant137of the distal end of the guide bar13and the slant227of the body21in combination define a continuous surface.

As shown inFIG. 10, the back surface of the guide bar13is introduced toward the front surface of the back piece23of the socket20. It should be noted that the back surface of the base11, which is adjacent to the back surface of the guide bar13across the step135, defines a continuous surface in combination with the exterior surface of the back piece23.

Therefore, when the plug10and the socket20are connected, the exterior surfaces of the above pieces of the socket20define the continuous surfaces so that the buckle1has a smooth appearance.

In the exemplary embodiment, the plug10and the socket20may be connected to each other after flipped over.

As shown inFIGS. 11 and 12, when the guide bar13is flipped over and inserted into the socket20through the insertion opening201, the front surface of the guide bar13is guided by the pair of peripheral portions221and the back surface of guide bar13is guided by the guiding step231so that the guide bar13is received in the slit204in the same manner as described above.

As shown inFIG. 13, for instance, the concave136of the back surface of the guide bar13is exposed in the slit204.

As shown inFIGS. 12 and 14, the step135of the back surface of the guide bar13protrudes from the exterior surface of each of the front pieces22.

While the appearance is different due to such a protrusion, the socket20and the plug10can be connected to each other even after flipped over.

When the socket20and the plug10are flipped over and connected, the step135of the back surface of the guide bar13protrudes from the exterior surface of each of the front pieces22and, for instance, the concave136of the back surface of the guide bar13is exposed in the slit204. Due to such differences in appearance, it is possible to find that the plug10and the socket20are flipped over.

As described above, in the exemplary embodiment, the socket20is provided with the slit204on a side where the front pieces22are provided. The slit204extends in the insertion direction longitudinally across the socket20to enhance efficiency in removing a foreign substance.

For instance, when a foreign substance enters the socket20through the insertion opening201while the plug10and the socket20are disconnected, the foreign substance may be swept out of the socket20along the slit204over the entire length in the insertion direction by moving a finger or a stick inserted in the slit204or applying compressed gas jetted from a nozzle (i.e., air blow).

A typical cylindrical socket is not provided with a slit extending along the entire length in an insertion direction as in the exemplary embodiment, so that a foreign substance has to be swept out in a restricted manner. In contrast, the socket20according to the exemplary embodiment is provided with the slit204extending along the entire length in the insertion direction of the body21, so that a foreign substance can be easily and reliably removed from the entire socket20.

In the exemplary embodiment, the lateral pieces24,25(i.e., the lateral sides) serve to reliably connect the front pieces22to the back piece23. Due to the arrangement of the front pieces22, the back piece23and the lateral pieces24,25, the body21has a C-shaped cross section intersecting with the insertion direction of the socket20. The body21has such a C-shaped cross section at any position defined in the insertion direction, so that the plug10can be inserted without any interference and a foreign substance can be reliably removed through the slit204.

In the exemplary embodiment, the bottom piece26provided opposite to the insertion opening201serves to reliably connect the front pieces22to the back piece23in combination with the lateral pieces24,25. Specifically, the bottom piece26and the lateral pieces24,25are arranged to define two orthogonal planes and can reliably have a rigidity required of an arrangement for connecting the front pieces22to the back piece23.

In the exemplary embodiment, the bottom piece26is provided with the cut261and the slit204extends across the body21from the insertion opening201to the cut261. With the slit204that extends longitudinally across the socket20, a function for removing a foreign substance can be ensured.

In the exemplary embodiment, the peripheral portion221of each of the front pieces22, which faces the slit204, functions to guide the guide bar13abutting against the peripheral portion221, so that the plug10can be smoothly inserted. Further, any other guiding arrangement is not necessitated, so that the socket20can be simplified in structure and reduced in weight.

In the exemplary embodiment, the peripheral portion221of each of the front pieces22, which has a guiding function, defines a contour flared toward the insertion opening201and protruding toward the slit204in an arc. Therefore, the plug10can thus be easily inserted through the insertion opening201due to a favorable guiding function

In the exemplary embodiment, when the plug10in a normal posture (i.e., in a state shown inFIGS. 7 and 8) is received in the slit204, the front surface of the guide bar13defines a continuous surface in combination with the front surfaces of the front pieces22. Therefore, while providing the guiding function as described above, the guide bar13closes the slit204when the plug10is connected, which results in an improved appearance of the buckle1.

In the exemplary embodiment, the peripheral portion of the front surface of the guide bar13is provided with the recessed step134, which is brought into abutment against the peripheral portion221of each of the front pieces22having the guiding function, so that the guide bar13exhibits the guiding function to connect the plug10to the socket20. Further, when the plug10and the socket20are connected, the step134of the guide bar13is engaged with the peripheral portion221of each of the front pieces22to effectively prevent the disconnection of the buckle1. Specifically, for instance, when an external force such as a bending force acts between the plug10and the socket20, the mutually fitted step134and peripheral portion221exhibit resistivity to such an external force to enhance a bending rigidity, thereby effectively preventing the buckle1from being accidentally unlocked.

The other advantageous effects described in the above explanation of the exemplary embodiment can also be considered as advantageous effects of the exemplary embodiment.

Incidentally, it should be understood that the scope of the invention is not limited to the above-described exemplary embodiment(s) but includes modifications and improvements as long as the modifications and improvements are compatible with the invention.

For instance, the slant137of the plug10and the slant227of the socket20are optional according to the invention and thus may be omitted as needed.

As shown inFIG. 7(B), the socket20includes the bottom piece26that is erected from the back piece23to be connected to each of the front pieces22via the slant227. However, a portion defined as the bottom piece26and the slant227may be modified to be in an arc or curve in side view and sectional view so as to connect the back piece23to each of the front pieces22. In this case, the bottom piece26and the slant227are considered as a part of the front pieces22and thus the slant137of the guide bar13of the plug10may accordingly be modified to be in an arc or curve in conformity with the shape of the socket20. The bottom piece26is only required to be a portion for connecting the back piece23and the front pieces22.

The step134of the guide bar13and the peripheral portion221of each of the front pieces22optionally abut against each other according to the invention and thus, alternatively, the guide bar13may be entirely received beneath the peripheral portion221of each of the front pieces22.

In the exemplary embodiment, the peripheral portion221of each of the front pieces22is in an arc as well as the peripheral portion of the guide bar13opposed to the peripheral portion221. Specifically, the peripheral portion221of each of the front pieces22is in an arc having a small-curvature portion toward the bottom piece26and a larger-curvature portion toward the insertion opening202and the peripheral portion of the front surface of the guide bar13is in a similar shape having a curvature increased toward the base11from the distal end of the guide bar13.

However, without departing from the scope of the invention, the above shape may be replaced by, for instance, an arc having a constant curvature, a shape that is continuously linear but partly curved, or a shape that linearly extends along the insertion direction.

FIGS. 15 and 16show another exemplary embodiment of the invention.

As shown in the figures, a buckle1A of this exemplary embodiment is different from the buckle1of the above exemplary embodiment shown inFIGS. 1 to 14in that: the slants137,227and the rib262are omitted; and the peripheral portion221of each of the front pieces22and the peripheral portion of the guide bar13opposed to the peripheral portion221have different shapes from the ones described above. It should be noted that the other arrangements according to this exemplary embodiment are the same as those of the above exemplary embodiment shown inFIGS. 1 to 14.

In this exemplary embodiment, while linearly extending from the bottom piece26toward the insertion opening202along the slit204, the peripheral portion221of each of the front pieces22is sharply curved outward in the width direction of the socket20toward the insertion opening201and further linearly extends slightly to the lateral piece24. Incidentally, a long linear portion of the peripheral portion221toward the bottom piece26is tilted relative to the insertion direction at a tilt angle that is sufficiently gentle as compared with that of a short linear portion toward the insertion opening201.

A front surface of the guide bar13of this exemplary embodiment has a peripheral portion shaped in conformity with the peripheral portion221of each of the front pieces22in the same manner as in the above exemplary embodiment. The peripheral portion of the guide bar13is provided with the protrusion133and the step134. The step134is brought into abutment against the peripheral portion221of each of the front pieces22.

FIGS. 17 and 18show still another exemplary embodiment of the invention.

As shown in the figures, a buckle1B of this exemplary embodiment is different from the buckle1of the above exemplary embodiment shown inFIGS. 1 to 14in that: the slants137,227, the rib262, the protrusion133and the step134are omitted; the guide bar13has a different shape from the one described above; and the peripheral portion221of each of the front pieces22also has a different shape from the one described above. It should be noted that the other arrangements according to this exemplary embodiment are the same as those of the foregoing exemplary embodiment shown inFIGS. 1 to 14.

In the socket20of this exemplary embodiment, the insertion opening20is in the form of an opening surface defined along the width direction, the slit204between the front pieces22extends along the insertion direction from an edge of the insertion opening202toward the bottom piece26, and the peripheral portion221of each of the front pieces22is thus linear along the insertion direction.

The guide bar13of this exemplary embodiment is in the form of a single stick projecting from the base11and is received in the slit204in the connected state. When received in the slit204, a peripheral portion of a front surface of the guide bar13is opposed to the peripheral portion221of each of the front pieces22along the peripheral portion221, so that the front surface of the guide bar13and the front pieces22in combination define a continuous surface. In other words, the step134of the guide bar13engaged with the peripheral portion221in the exemplary embodiment ofFIG. 1and the exemplary embodiment ofFIG. 15is not provided in this exemplary embodiment.

Similarly, in this exemplary embodiment shown inFIG. 17as well as the above exemplary embodiment shown inFIG. 15, the socket20is provided with the slit204on the side where the front pieces22are provided. The slit204extends longitudinally across the socket20in the insertion direction to enhance efficiency in removing a foreign substance.

It is not necessary that the front surface of the guide bar13is configured to define a flush continuous surface in combination with the front pieces22. Further, it is not necessary that the peripheral portion221of each of the front pieces22is configured to guide the guide bar13.

The bottom piece26may be omitted. In this case, it is desired that a support rigidity provided by the lateral pieces24,25be enhanced so that the back piece23and the lateral pieces24,25can define the C-shaped cross section.

In the above exemplary embodiment, the side release buckle1including the pair of lock arms12is explained. However, the invention is applicable to a center lock buckle or front release buckle that includes a wide-width lock arm disposed along the back piece23. In this case, for instance, a release button may be disposed in the slit204of the socket20with both sides of the wide-width lock arm being held by the pair of front pieces22.

In the above exemplary embodiment(s), the lateral pieces24,25and the bottom piece26are used to connect the pair of front pieces22to the back piece23. However, as long as the rigidity of the lateral pieces24,25is increased, it is not necessary to use the bottom piece26to support the front pieces22and the back piece23in the intersecting directions and thus the bottom piece26may be omitted as needed.

A single lateral piece or three or more lateral pieces may be provided in place of the two lateral pieces24,25. A single lateral piece may ensure a sufficient rigidity as long as the lateral piece has a length covering the entire length of the socket20defined in the insertion direction. When a single lateral piece with a small dimension is used, it is desired that the bottom piece26be used in combination.

In the above exemplary embodiment(s), for instance, the peripheral portion221of each of the front pieces22, the guiding step231of the back piece23, the guide members223,233adjacent to the engaged portions28, and the step135of the guide bar13are configured to provide the guiding function for connecting the plug10and the socket20. However, these components may be modified or omitted as needed. The step135and the concave136provided to the back surface of the plug10may be omitted as needed.

The belt attachments19,29may have shapes different from the ones described above in the exemplary embodiment(s). Accordingly, either one of the belt attachments19,29may be configured not to be attached with a belt but to be fixed to a different article.

Additionally, the respective dimensions, shapes and materials of the components may be appropriately selected in the implementation of the invention.