WO2016006414A1

WO2016006414A1 - Folding chair

Info

Publication number: WO2016006414A1
Application number: PCT/JP2015/067745
Authority: WO
Inventors: 保濁川
Original assignee: 株式会社イケックス工業
Priority date: 2014-07-10
Filing date: 2015-06-19
Publication date: 2016-01-14
Also published as: JP2016027836A; CN106659301B; JP5763814B1; CN106659301A

Abstract

A folding chair (10) has two bendable board members (20) disposed one on top of the other with at least two parts of the two board members (20) in contact with each other, and by bending and stretching the board members (20) the folding chair (10) is configured to be able to open and close into: an open state, wherein the two board members (20) have moved in directions so as to move away from each other; and a closed state, wherein the two board members (20) have moved in directions so as to approach each other. The chair (10) is formed so that in the open state, one side forms a vessel shape having an open part (13) and a seat surface part (14) on the opposite side of the opening part (13) to receive weight from a user.

Description

Folding chair

Embodiment of this invention is related with a folding chair.

As the folding chair, for example, a folding chair that includes a frame formed by bending a metal pipe and a cloth that forms a seat portion is known. In such a folding chair, for example, two frames are configured to be rotatable about an axis. And the cloth which forms a seat surface part is provided over two frames. When the two frames are pivoted open, the fabric is pulled between the two frames and stretched between the frames. As a result, a seating surface portion is formed, and the folding chair functions as a chair.

However, in the folding chair having such a conventional configuration, the thickness of the frame itself remains even in the folded state. For this reason, such a chair is bulky when stored and carried even in a folded state, and there is room for improvement in terms of storage and portability.

Japanese Patent Laid-Open No. 2014-256

Therefore, we will provide folding chairs with improved storage and portability.

In the folding chair according to the embodiment, in a state where two foldable plate members are stacked and connected, at least two sides of the two plate members are connected to each other, and the plate member is bent and stretched to 2 The plate member is configured to be openable and closable in an open state in which the plate members are moved away from each other and a closed state in which the two plate members are moved toward each other. In the open state, the chair has a container shape having an opening on one side, and a seat surface portion that receives a load from the user is formed on the side opposite to the opening.

According to this, the chair in the closed state is in a state in which two plate members are stacked. That is, since the chair of the embodiment does not use parts such as a metal pipe, the thickness of the metal pipe or the like does not remain in a folded state. Therefore, the chair of the embodiment can be made as thin as possible in the closed state, and as a result, the storability and portability of the chair are improved.

The seat surface portion of the chair according to the embodiment has an elliptical shape that is long in a direction perpendicular to the opening and closing direction, and is curved so as to move away from the edge on the opening side toward the outside from the center portion of the elliptical longitudinal direction. Yes.
That is, when the seat surface portion is formed into a simple flat plate shape, when the user sits on the chair, the user's buttocks are unlikely to be in close contact with the seat surface portion. Therefore, for example, if the seat surface portion is made of a hard synthetic resin material or the like, the sitting comfort is deteriorated. On the other hand, as for the chair of embodiment, the seat surface part is curving. For this reason, when the user sits on the chair, the user's buttocks easily adhere to the seat surface. Therefore, for example, even if the seat surface portion is made of a hard synthetic resin material or the like, the sitting comfort is good. As a result, for example, the fatigue of the user when the chair is used for a long time can be reduced.

In the open state, the side surface portion of the chair of the embodiment has a greater distance from the other side surface portions facing each other as it goes from the seat surface portion side to the opening portion side.
That is, the side surface portion in the open state transmits a load applied to the seating surface portion to the ground surface or the floor surface, which is the installation surface, and is a portion that replaces the conventional frame. The side part of the chair of the embodiment is configured in a plate shape by a plate member. Therefore, the chair is strong against a load in a direction parallel to the surface of the side surface portion, but is relatively weak against a load in a direction perpendicular to the surface of the side surface portion. In this case, when the side surface portion is provided at a right angle to the seat surface portion, that is, perpendicular to the installation surface, the load resistance in the vertical direction increases, but the load resistance in the front-rear and left-right directions becomes relatively weak. However, it is also assumed that the user moves his / her body in the front / rear / left / right direction while sitting on a chair. Therefore, it is necessary to enhance the load resistance not only in the direction perpendicular to the installation surface but also in the front-rear and left-right directions. Therefore, by expanding the side surface portion of the chair as it goes to the opening side in the open state, it is possible to improve load resistance not only in the direction perpendicular to the installation surface but also in the left and right and front and rear directions.

The perspective view which shows the closed state of the folding chair by one Embodiment Front view showing closed state of folding chair Plan view showing the closed state of the folding chair Bottom view showing closed state of folding chair Right side view showing the closed state of the folding chair The perspective view which shows the open state of a folding chair Front view showing the open state of the folding chair The top view which shows the open state of a folding chair Bottom view showing the open state of the folding chair Right side view showing the open state of the folding chair Front view showing plate member Sectional view taken along line X12-X12 in FIG.

A folding chair according to an embodiment will be described with reference to the drawings.
In each figure, FIGS. 1 to 5 are views showing a closed state of the folding chair 10. FIG. 6 to 10 are views showing the folding chair 10 in the open state. In addition, since the left view which shows the closed state of the folding chair 10 is the same as FIG. 5, it is abbreviate | omitting. Similarly, since the left side view which shows the open state of the folding chair 10 is the same as FIG. 10, it is abbreviate | omitting. The folding chair 10 is configured in a plate shape as a whole in the closed state, and exhibits a function as a chair in the open state.

In the following description, it is simply referred to as a chair 10. In the following description, the front and rear, the left and right, and the top and bottom of the chair 10 are as indicated by arrows in each figure. The user uses the chair 10 by bringing the lower portion of the chair 10 in an open state into contact with the ground or floor as the installation surface. In the opened state, the chair 10 of the present embodiment has a vertical dimension or height of about 25 cm, a horizontal dimension or width of about 40 cm, and a front-back dimension or depth of about 20 cm. The specific dimensions of the chair 10 are not limited to those described above.

The chair 10 includes two

plate members

20 and 20. The two

plate members

20 and 20 are components having the same configuration. The plate member 20 is a molded product of a resin material such as polypropylene, for example, and is configured as a single plate as shown in FIG. The plate member 20 has a plurality of groove portions, in this case, a first groove portion 21, a second groove portion 22, a third groove portion 23, and a fourth groove portion 24. The plate member 20 is configured to be bendable along the groove portions 21 to 24.

In the following description, when the two surface portions located on both sides of the groove portion are bent in a direction away from each other, it is called mountain fold. Moreover, it is called valley folding that two surface parts located on both sides across the groove part bend in a direction approaching each other. In this case, the surface portion refers to a surface exposed to the outside among the surfaces of the plate member 20.

The plate member 20 integrally includes a seat surface forming portion 30 and a side surface forming portion 40. The side surface forming part 40 is provided below the seat surface forming part 30. As shown in FIG. 11, the seat surface forming portion 30 has a shape in which a part of an elliptical shape that is long in the left-right direction is cut out. Specifically, the seat surface forming unit 30 includes an elliptical periphery, a line 301 (hereinafter, referred to as a long side 301) from one vertex to the center of the elliptical longitudinal direction, and an elliptical lateral direction. A region formed by a line 302 (hereinafter referred to as a short side 302) from one apex to the center thereof, in this case, a shape obtained by cutting out about ¼ of an elliptical shape.

The seat surface forming part 30 has a first seat surface region 31, a second seat surface region 32, and a third seat surface region 33. The first seat surface region 31 is a region in contact with the long side 301 and the second groove portion 22 in the seat surface forming portion 30, and is about ¼ of an elliptical shape. The second seat surface region 32 is a region in contact with the short side 302 in the seat surface forming portion 30 and has a size of about ¼ of an elliptical shape. The third region is a region that does not contact any of the long side 301 and the short side 302 in the seating surface forming unit 30, and is about ¼ of an elliptical shape.

The first groove portion 21 is provided between the second seat surface region 32 and the third seat surface region 33 in the seat surface forming portion 30. The first groove portion 21 is a mountain-fold groove formed in a straight line. That is, the second seat surface region 32 and the third seat surface region 33 can be bent to the side where the surface portions are separated from each other by the first groove portion 21. That is, the second seat surface region 32 can be bent with respect to the third seat surface region 33 toward the back side of the sheet of FIG.

The second groove portion 22 is provided between the seat surface forming portion 30 and the side surface forming portion 40. The second groove portion 22 is a mountain fold groove formed in an elliptical arc shape along the periphery of the seat surface forming portion 30. The seat surface forming part 30 and the side surface forming part 40 are separated from each other on both ends of the second groove part 22. That is, the edge portions of the seat surface forming portion 30 on the first seat surface region 31 and the third seat surface region 33 side are respectively from the elliptical apex portion of the seat surface forming portion 30 to the apex portion side in the short direction. Toward, it is separated from the side surface forming part 40 over a distance of about 1/3. The side surface forming portion 40 and the seat surface forming portion 30 can be bent by the second groove portion 22 to the side where the surface portions are separated from each other. That is, the seat surface forming unit 30 can be bent with respect to the side surface forming unit 40 toward the back side in FIG.

The side surface forming portion 40 is connected to the first seat surface region 31 and the second seat surface region 32 of the seat surface forming portion 30. The side surface forming portion 40 has a substantially trapezoidal shape as a whole, including the first seat surface region 31 and the second seat surface region 32 of the seat surface forming portion 30. The side surface forming portion 40 is bilaterally symmetric with respect to the center portion in the left-right direction of the side surface forming portion 40. The side surface forming part 40 has a first side surface region 41, two second side surface regions 42, and two third side surface regions 43.

The first side surface region 41 is provided in the lateral center of the side surface forming portion 40. The first side surface region 41 is a region surrounded by the lower edge portion of the side surface forming portion 40, the second groove portion 22, and the two third groove portions 23. The two second side surface regions 42 are respectively provided on the left and right sides of the first side surface region 41. The second side surface region 42 is a region surrounded by the upper and lower edges of the side surface forming portion 40, the third groove portion 23, and the fourth groove portion 24. The two third side surface regions 43 are respectively provided at both side end portions of the side surface forming portion 40 in the left-right direction. The third side surface region 43 is formed in a rectangular shape that is long in the vertical direction.

The side surface forming part 40 has two third groove parts 23 and two fourth groove parts 24. The third groove portion 23 is a mountain-fold groove formed in an S-shape or a reverse S-shape curve. The third groove portion 23 is formed in a curved shape extending in the vertical direction from both end portions of the second groove portion 22 to the lower edge portion of the side surface forming portion 40. As for the 3rd groove part 23, the curvature has changed in the middle part of the up-down direction. That is, the third groove portion 23 is formed in an arc shape that slightly bulges outward in the left-right direction of the side surface forming portion 40 from the end portion of the second groove portion 22 to the middle portion of the side surface forming portion 40 in the vertical direction. Yes. Thereafter, the curvature of the third groove portion 23 is changed, and the third groove portion 23 is formed in an arc shape that slightly swells inward in the left-right direction of the side surface forming portion 40 from the middle portion in the vertical direction of the side surface forming portion 40 to the lower end portion. The distance between the two third groove portions 23 is the maximum on the seat surface forming portion 30 side, that is, the upper side, and the distance opposite to the seat surface forming portion 30, that is, the lower side is the minimum. That is, the distance between the two third groove portions 23 gradually decreases from the upper side to the lower side.

The third groove portion 23 is provided between the first side surface region 41 and the second side surface region 42. Therefore, the first side surface region 41 and the second side surface region 42 can be bent in a direction in which the surface portions are separated from each other with the third groove portion 23 as the center. In this case, the second side surface regions 42 provided on both the left and right sides with respect to the first side surface region 41 can be bent toward the back side of the sheet of FIG.

The fourth groove portion 24 is a groove that becomes a fold when the two

plate members

20 and 20 open and close in the front-rear direction, that is, in the thickness direction of the

plate members

20 and 20. In the case of this embodiment, the 4th groove part 24 is the groove | channel of the valley fold formed in the linear form extended to an up-down direction. The fourth groove portion 24 is provided between the second side surface region 42 and the third side surface region 43. Therefore, the second side surface region 42 and the third side surface region 43 can be bent in the direction in which the surface portions approach each other around the fourth groove portion 24. In this case, the second side surface region 42 can be bent toward the front side in FIG.

The seat surface forming portion 30 has three first hole portions 34 and three second hole portions 35. The first hole portion 34 and the second hole portion 35 are each formed through the seat surface forming portion 30 in a circular shape. The inner diameter of the first hole 34 and the second hole 35 are the same. The three first holes 34 are respectively located in the vicinity of the apex in the short direction of the ellipse and in the vicinity of the apex in the longitudinal direction of the ellipse at the periphery of the first bearing surface region 31. It is provided in the middle part of the

holes

34 and 34.

The three second hole portions 35 are arranged in the vicinity of the apex portion in the short side direction of the elliptical shape and in the vicinity of the apex portion in the longitudinal direction of the elliptical shape at the peripheral edge portion of the second bearing surface region 32, respectively. It is provided in the middle part of the

holes

35 and 35. In this case, the first hole portion 34 and the second hole portion 35 are arranged point-symmetrically with respect to the center portion of the seat surface forming portion 30.

The side surface forming part 40 has six third hole parts 44, a long hole part 45, and a stopper 11. The third hole 44 is formed through the side surface forming part 40 in a circular shape. In this case, the inner diameter of the third hole 44 is the same as the inner diameter of the first hole 34 and the second hole 35. Three third holes 44 are provided for each of the two third side surface regions 43. The third hole portion 44 is disposed along the longitudinal direction of the third side surface region 43. That is, the third hole portion 44 is provided in the trapezoidal four corners of the side surface forming portion 40 and the intermediate portion in the vertical direction at the left and right edge portions.

The long hole portion 45 is provided in the side surface forming portion 40 at a central portion in the left-right direction and a slightly lower portion in the vertical direction. In other words, the long hole portion 45 is provided in a portion slightly below the first side surface region 41 of the side surface forming portion 40. The long hole portion 45 is formed through the side surface forming portion 40 in a long hole shape that is long in the left-right direction. The user can use the long hole portion 45 as a handle when carrying the chair 10.

The stopper 11 is, for example, a metal or resin snap button or hook. The stopper 11 is provided in the side surface forming portion 40 at a central portion in the left-right direction and slightly below the vertical direction. In this case, the stopper 11 is provided at the central portion in the left-right direction of the long hole portion 45 and on the upper side of the long hole portion 45, that is, on the seat surface forming portion 30 side.

As shown in FIGS. 1 to 5, the two plate members 20 are superposed with their inner surfaces facing each other. Then, a fixture 12 such as a rivet is passed through each third hole 44 so as to penetrate the two plate members 20. Accordingly, the side surface forming portions 40 are connected to each other in the two plate members 20. That is, the two left and right sides of the two plate members 20 are connected to each other.

Further, the second seat surface region 32 of the seat surface forming portion 30 of the plate member 20 is folded into a mountain fold so as to cover the first seat surface region 31 of the seat surface forming portion 30 of the other plate member 20. At that time, the second hole 35 of one plate member 20 and the first hole 34 of the other plate member 20 are overlapped. And the fixing tool 12, such as a rivet, penetrates the second seat surface region 32 of one plate member 20 and the first seat surface region 31 of the other plate member 20, so that the second hole 35 and the first It is passed through the hole 34. As a result, the seat surface forming portions 30 are connected to each other in the two plate members 20. In a state where the two plate members 20 are connected to each other, three sides of the four sides of the trapezoidal plate member 20 as a whole are closed, and the bag is formed in a bag shape with one side opened.

1 and 6, the chair 10 configured as described above can be opened and closed in the front-rear direction, that is, in the thickness direction of the plate member 20 by the action of the first groove portion 21 to the fourth groove portion 24. That is, the chair 10 is configured to be openable and closable in an open state and a closed state by bending and extending both side portions of the groove portions 21 to 24 of the plate member 20. The open state means a state in which the two

plate members

20 and 20 are moved in a direction away from each other. Further, the closed state refers to a state in which the two

plate members

20 and 20 are moved in a direction approaching each other. The chair 10 has a substantially plate shape in the closed state as shown in FIGS. On the other hand, the chair 10 is in a container shape having an opening 13 on one side, that is, the lower side, as shown in FIGS. The chair 10 exhibits a function as a chair in the open state. That is, in the open state, the chair 10 includes the seat surface portion 14 and the side surface portion 15.

The seat surface portion 14 is formed by the second seat surface region 32 and the third seat surface region 33 of each seat surface forming portion 30 in the two plate members 20. The seat surface portion 14 is a portion that is provided on the side opposite to the opening 13, that is, on the upper side, and that receives a load from the user. In other words, the seat surface portion 14 is a portion that comes into contact with the user's buttocks when the user sits on the chair 10. As shown in FIG. 8, the seat surface portion 14 has an elliptical shape that is long in the left-right direction in plan view. Further, as shown in FIG. 7, the seat surface portion 14 is curved so as to be separated from the edge portion on the opening portion 13 side as it goes outward from the center portion of the elliptical longitudinal direction in the front view. That is, the seat surface portion 14 is curved upward as it goes outward from the center portion in the left-right direction in a front view.

In addition, the chair 10 in the open state is configured in a trapezoidal shape with a wide lower side as shown in FIGS. 7 and 10 in a plan view and a side view. That is, when the chair 10 is in the open state, the distance between the side surface portion 15 that forms the periphery of the opening portion 13 and the other side surface portion 15 that opposes increases from the seat surface portion 14 side toward the opening portion 13 side. ing.

According to the above embodiment, the chair 10 is configured by stacking two plate members 20 configured to be bendable. The two plate members 20 have at least two sides, in this case, the left and right edges of the side surface forming portion 40 connected to each other. The chair 10 is in an open state when the two plate members 20 are moved away from each other, and is in a closed state when moved in a direction approaching each other. And the chair 10 becomes a container shape which has the opening part 13 in one side, ie, the lower side, and the seat surface part 14 is formed in the opposite side to the opening part 13 in an open state.

According to this, the chair 10 becomes plate shape which has the thickness of the plate member 20 for 2 sheets in a closed state. Therefore, the chair 10 can be made as thin as possible in the closed state. As a result, the storability and portability of the chair 10 are improved. Furthermore, since the closed chair 10 is plate-shaped, for example, even when a plurality of chairs 10 are stacked, it is difficult to be bulky. Therefore, the storage property and portability in the case of stacking a plurality of chairs 10 are also improved.

The chair 10 is mainly composed of two plate members 20 that are resin molded products, and does not require parts such as metal pipes. Therefore, since metal parts can be reduced as much as possible, the weight can be reduced compared to a chair of the same size.

The seat surface portion 14 in the open state of the chair 10 has an elliptical shape that is long in the left-right direction, and is curved upward. That is, the seat surface portion 14 is formed in an arch shape that goes upward as it goes outward from the center portion in the left-right direction. For this reason, when the user sits on the chair 10, the user's buttocks easily adhere to the seat surface portion 14. Therefore, the chair 10 is easier to sit than the seat surface portion 14 is simply a flat plate. As a result, it is possible to reduce the fatigue of the user when the chair 10 is used for a long time.

In the open state, the distance between the side surface portion 15 forming the periphery of the opening portion 13 and the other side surface portion 15 that faces the side surface portion 15 increases from the seat surface portion 14 side toward the opening portion 13 side. Specifically, the chair 10 is formed so that the lower side, that is, the opening 13 side is wide in the open state. That is, the chair 10 is configured so that the lower side extends in the left-right direction and the front-rear direction in the open state. For this reason, the load resistance of the chair 10 in the left-right direction and the front-back direction is improved. As a result, the chair 10 is improved in stability when the user is sitting.

Moreover, according to the said embodiment, a load resistance can be raised about the folding chair 10 of the open state by the 3rd groove part formed in the S-shaped curve shape. That is, the side surface forming part 40 of the chair 10 has a first side surface region 41 and two second side surface regions 42. The first side surface region 41 is a region surrounded by the lower edge portion of the side surface forming portion 40, the second groove portion 22, and the two third groove portions 23, and is provided at the center in the left-right direction of the side surface forming portion 40. Area. The second side surface region 42 is a region surrounded by the upper and lower edges of the side surface forming portion 40, the third groove portion 23, and the fourth groove portion 24, and is a region provided on both the left and right sides of the first side surface region 41. is there.

Here, both the second groove portion 22 and the third groove portion 23 surrounding the first side surface region 41 are configured in a mountain fold. Therefore, when the chair 10 is opened, the first side surface region 41 is gently curved so as to bulge outward with respect to the central side in the horizontal direction of the chair 10 as shown in FIG. On the other hand, when viewing the third groove portion 23 and the fourth groove portion 24 surrounding the second side surface region 42, the third groove portion 23 is configured in a mountain fold, but the fourth groove portion 24 is configured in a valley fold. Therefore, when the chair 10 is opened, the second side surface region 42 is gently curved so as to be recessed toward the center side in the horizontal direction of the chair 10 as shown in FIG. As described above, when the chair 10 is in the open state, the first side surface region 41 and the second side surface region 42 constituting the side surface portion are directed in directions different from each other with respect to the horizontal center side of the chair 10. Curves gently.

Here, for example, when comparing the load resistance in the vertical direction for a cylinder and a prism, it is known that the cylinder has a higher load resistance than the prism. Therefore, the load resistance in the vertical direction can be improved, for example, by curving the side surface forming portion 40 in an arc shape. However, in this case, there are the following problems just by making the side surface forming portion 40 into a simple arc shape, for example. That is, when a force in the horizontal direction is applied from the outside to a point having a simple arc-shaped side surface forming portion, a load in the vertical direction is concentrated on an action point of the load in the horizontal direction. As a result, the side surface forming portion buckles relatively easily.

On the other hand, when the chair 10 of this embodiment is opened, the first side surface region 41 and the second side surface region 42 are folded by the action of the third groove portion 23 as shown in FIGS. The chair 10 is gently curved toward different directions with respect to the horizontal center side. According to this configuration, the load in the vertical direction with respect to the chair 10 is distributed to the first side surface region 41 and the second side surface region 42. Therefore, for example, even if a horizontal load acts on a certain point of the first side surface region 41, the vertical load received by the second side surface region 42 is equal to the horizontal load of the first side surface region 41. It becomes difficult to concentrate on the point of action. Similarly, for example, even when a horizontal load is applied to a point in the second side surface region 42, the vertical load received in the first side surface region 41 is the horizontal load in the second side surface region 42. It becomes difficult to concentrate on the point of action. Thereby, according to this embodiment, a load resistance can be made high compared with the case where the side surface formation part 40 is formed in simple arc shape.

Here, in order to demonstrate the load resistance of the chair 10 according to the above embodiment, the applicant follows the test implementation regulations of JIS S 1203: 1998 “Furniture-chairs and stools—strength and durability test method”. The test was conducted. In the test method, a predetermined force is applied to the center of the seating surface forming portion 30 through a small seating surface contact plate having a diameter of 200 mm. As a result, the result that the chair 10 of the said embodiment can endure the load of 1500N was obtained.

The present invention described above is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the scope of the invention.
The plate member 20 is not limited to a resin material such as polypropylene, and may be a lightweight metal such as aluminum, wood, or the like. In this case, instead of the grooves 21 to 24, for example, by providing a hinge or the like, the plate member can be configured to be bendable.
The second seating surface region 32 of the seating surface forming unit 30 may not be connected to the first seating surface region of the other seating surface forming unit 30. That is, in the open state of the chair 10, the second seat surface region 32 of one plate member 20 may be simply placed on the first seat surface region 31 of the other plate member 20.
The size of the chair 10 can be changed as appropriate according to the user, the usage environment, the purpose of use, and the like.

Moreover, the 4th groove part 24 can also be set as the following structures, for example. That is, although not shown in detail, the fourth groove portion 24 is a mountain-fold groove. The third side surface regions 43 of the two

plate members

20 and 20 are respectively bent to the inner side of the chair 10, that is, the side where the opposed third side surface regions 43 are close to each other. And the surface part of the 3rd side surface area | region 43 which opposes mutually is adhere | attached. According to this configuration, the second side surface region 42 and the third side surface region 43 can be bent in the direction in which the surface portions are separated from each other by folding the fourth groove portion 24. Thus, the two

plate members

20 and 20 can be opened and closed with the fourth groove portion 24 being folded. Therefore, the same effect as the above embodiment can be obtained.

Claims

In a state where two foldable plate members are stacked and connected, at least two sides of the two plate members are connected to each other, and the plate members are bent and stretched so that the two plate members are mutually connected. Are opened and closed in a direction in which the two plate members are moved toward each other, and can be opened and closed.
In the open state, it becomes a container shape having an opening on one side, and a seat surface portion that receives a load from a user is formed on the opposite side to the opening,
The plate member is
A seat surface forming portion that forms the seat surface portion;
A side surface forming portion formed integrally with the seat surface forming portion and forming a side surface portion around the opening;
A first groove which is a mountain-folded groove provided in the seating surface forming portion and extending in a direction perpendicular to the opening and closing direction of the two plate members;
A mountain-folded second groove formed between the seat surface forming portion and the side surface forming portion and formed in an elliptical arc shape along the seat surface forming portion;
In the seat surface forming portion, it swells in an arc shape from both end portions of the second groove portion to a middle portion in the vertical direction of the side surface forming portion, and then swells in an arc shape toward the outside in the left and right direction of the side surface forming portion. Two third groove portions that are mountain-folded grooves formed in a curved shape extending in the vertical direction so as to swell in an arc shape toward the inner side in the left-right direction of the side surface forming portion from a middle portion in the direction to the lower end portion; ,
Two fourth groove portions that are formed in the side surface forming portion and extend in the vertical direction at both lateral end portions of the side surface forming portion and serve as folds when the two plate members open and close;
The side surface forming part is
A region surrounded by the lower edge portion of the side surface forming portion, the second groove portion, and the two third groove portions, and a first side surface region provided at a central portion in the left-right direction of the side surface forming portion;
An area surrounded by upper and lower edges of the side surface forming portion, the third groove portion, and the fourth groove portion, and two second side surface regions provided on the left and right sides of the first side surface region, Have
The two plate portions are folding chairs that can be opened and closed in the thickness direction of the plate member by the action of the first groove portion, the second groove portion, the third groove portion, and the fourth groove portion.
The seat surface portion has an elliptical shape that is long in a direction perpendicular to the opening and closing direction, and is curved so as to move away from the edge portion on the opening portion side toward the outside from the central portion of the elliptical longitudinal direction. Item 2. A folding chair according to item 1.
The side surface forming the periphery of the opening in the open state increases in distance from the other side surface facing the side surface from the seat surface side to the opening side. Folding chair.