Folding chair

Abstract

To provide a folding chair 60 that can be self-supported by maintaining grounding of a lower end part 22 of a front leg frame 20 and a lower end part 32 of a rear leg frame 30 when being folded.SOLUTION: A folding legless chair 60 is composed of a front leg frame 20, a rear leg frame 30, and a roughly horizontal seat frame 1. The freely expandable upper end part 35 of the rear leg frame 30 is freely rotatably connected to the front leg frame 20 on a first horizontal axis 27, while the seat frame 1 is freely rotatably connected to the front leg frame 20 on a second horizontal axis 7. A tip of a first metal piece 44 of the rear leg stay 40 fastened to the rear leg frame 30 and a tip of a second metal piece 14 of the seat stay 10 fastened to a lower surface 4a of the seat frame 1 are freely rotatably connected to each other. At the point of use, the lower end part 22 of the front leg frame 20 and the lower end part 32 of the rear leg frame 30 are grounded, and the front end 2 of the seat frame 1 is caused to rise and rotate. Thereby grounding of both lower end parts 22, 32 can be maintained even if the front leg frame 20 and the rear leg frame 30 are narrowed down and folded.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a folding chair having a seat frame connected to a front leg frame and a rear leg frame. [Background technology]

[0002] The present invention is a folding chair that includes a pair of front leg frames whose lower ends are grounded and whose upper ends are connected to each other, a pair of rear legs whose lower ends are grounded and whose upper ends are connected to the middle of the front leg frames, and a seat frame connected to the front leg frames and the rear leg frames, and that can be used as a chair by opening the front leg frames and the rear leg frames (in use state) and can be stored by closing them (folded state). In particular, we aim to realize a structure in which both the lower ends of the front leg frames and the lower ends of the rear leg frames are grounded in the folded state, allowing the chair to be stably leaned against something when folded. In a conventional chair, for example, according to Patent Document 1, the lower region of the connecting column 18 is slidably fitted into the column body 17 made of a pipe material of the rear column legs 13L, 13R, and the upper end of the connecting column 18 is connected to the front column legs 13L, 13R by the shaft 12. In this structure, the seat body 20 is connected to the rear column legs 11L, 11R by the first pivot 24. Therefore, in Patent Document 1, the distance between the pin 12 and the first pivot 24 can be greatly changed between when in use and when folded, so that stability when in use and compact folding can be achieved. The present application is also based on this structure. Also, in Patent Document 2, a front caster 9 is attached to the front leg 3, and a rear caster 10 is attached to the rear leg 4, and a long guide hole 13 is provided in the rear leg 4 in the axial direction, and a slide pin 15 for the seat 1 is attached to the long guide hole 13. The slide pin 15 moves within the long guide hole 13, so that the seat 1 is erected and the rear leg 4 and the front leg 3 are brought closer together, allowing nesting with the casters 9, 10 in contact with the ground. Patent Document 3 describes a folding chair with four seats 6 lined up horizontally, with the horizontal rear legs 2 and front legs 1 being an integrated structure, with the seats 6 resting on shafts 4 of the front legs 1. The document also describes a structure in which there are no shafts directly connecting the legs 2 and the seats 6, and they are connected only by connecting plates 5. The purpose of this folding chair is to maintain a stable folded state with the four seats 6 upright, without returning to their usable state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-80773 A [Patent Document 2] JP 2022-186319 A [Patent Document 3] Jpn. Jpn. Published No. 37-24032 Summary of the Invention [Problem to be solved by the invention]

[0004] Although Patent Document 1 provides the above-mentioned effects, it has the problem that, when folded, it is not possible to adjust the dimensions so that both the lower ends of the front leg columns 13L, 13R and the lower ends of the rear leg columns 11L, 11R are in contact with the ground. Furthermore, in Patent Document 2, it is essential to provide the long guide holes 13 in the pipes of the rear legs 4, which inevitably reduces the strength of these parts. Also, in order to maintain a stable folded state without returning to the usage state when the rear legs 2 and seat 6 are used in an upright position using only the connecting plate 5 of Patent Document 3, it is assumed that only the front legs 1 touch the ground when folded, and the rear legs 2, seat 6, and connecting plate 5 are arranged in a straight line in a floating state. Therefore, even if it were possible to adjust the length so that both the front legs 1 and the rear legs 2 touch the ground, there would be a problem of stability being lost when folded. [Means for solving the problem]

[0005] This invention solves the above problem by providing a shape maintaining mechanism on the underside of the seat frame that absorbs deformation caused by extension of the rear leg frame in the folded state and changes in the relative positions of the two frames caused by rotation of the seat frame.

[0006] That is, the basic invention is a folding chair that can be transformed into a usable state where a user sits and a folded state, This folding chair is characterized in that it comprises a pair of front leg frames, a pair of rear leg frames, and a substantially horizontal seat frame, the lower ends of the front leg frames being grounded and the upper ends being connected by an upper connecting member, the lower ends of the rear leg frames being grounded and the upper ends being connected to the upper part of the front leg frames, the middle part of the seat frame being sandwiched in the width direction by the middle part of the front leg frames and being rotatably connected to the front leg frames at said part by a second horizontal axis, and is configured to satisfy all of the following requirements. (1) Each of the rear leg frames is formed from a rear leg base portion whose lower end is grounded, and a rear leg upper end portion which is axially movable and extendable relative to the rear leg base portion. (2) Each of the front leg frames was rotatably connected to the upper end of the rear leg upper end of each of the rear leg frames at a position above the seat frame by a first horizontal axis. (3) The intermediate portions of the front leg frames and the seat frame are connected to each other below the first horizontal axis so as to be freely rotatable about a second horizontal axis formed on the seat frame. (4) A shape maintenance mechanism is provided which absorbs deformation due to extension of the rear leg frame and changes in the relative positions of each frame due to the seat frame rotating around the second horizontal axis in the folded state, and the seat frame and the rear leg frame are connected via the shape maintenance mechanism. (5) The shape retention mechanism is configured by rotatably connecting, directly or via other members, a first metal fitting provided on the front leg side of the rear leg frame and on the underside of the seat frame to a second metal fitting protruding from the underside of the seat frame. (6) The shape retention mechanism is structured so that, in the use state and the folded state, the lower end of the front leg frame and the lower end of the rear leg base of the rear leg frame both maintain contact with the ground, so that the seat frame is in a substantially horizontal position in the use state and is in an upright position in the folded state. (7) The lower ends of the front landing gear frames and the rear landing gear frames are not provided with means for rotating with respect to the ground surface, and are designed so that they do not easily move relative to the ground surface when in use.

[0007] In the above, the invention corresponding to the first embodiment is a folding chair characterized by being configured to satisfy all of the following requirements: (1) A rear leg stay is installed between the rear leg frames, on the front leg frame side of the rear leg frames and on the underside of the seat frame, and a first metal fitting is fixed to the rear leg stay. (2) The rear leg stay is composed of a leg fixing member fixed to the rear leg frame and a leg installation member connecting both the leg fixing members, and the first metal fitting is fixed to the leg installation member. (3) A seat stay is installed between the second horizontal axis and the rear leg frame on the underside of both sides of the seat frame, and a second metal fitting is fixed to the seat stay. (4) The seat stay is composed of a seat fixing member fixed to both sides of the seat frame and a seat installation member connecting the two seat fixing members, and the second metal fitting is fixed to the seat installation member. The present invention also provides a folding chair characterized in that it is configured to satisfy all of the following requirements. (1) The first and second metal fittings are small plate-shaped first metal fitting pieces and second metal fitting pieces, and the first metal fitting piece is fixed to the leg mounting member with its tip inclined toward the second metal fitting piece, and the second metal fitting piece is fixed to the seat fixing member with its tip inclined toward the first metal fitting piece. (2) The tip end of the first metal piece and the tip end of the second metal piece are rotatably connected to each other. Furthermore, the present invention provides a folding chair characterized in that it is configured to satisfy all of the following requirements: (1) A stopper is provided on the underside of the seat frame, between the seat stay and the rear leg frame when viewed from the side, protruding downward. (2) The stopper is not in contact with the rear leg stay or the seat stay in the use state, and is in contact with the leg support member of the rear leg stay in the folded state.

[0008] Moreover, the invention corresponding to the second embodiment is a folding chair characterized by being configured so as to satisfy all of the following requirements. (1) The first and second metal fittings are small plate-shaped first and second metal fitting pieces, and the first metal fitting piece is fixed to the rear leg frame at a position on the front leg frame side facing the front leg frame, and the first metal fitting piece is positioned on the underside of the seat frame. (2) A second metal fitting piece was fixed downward to the underside of the seat frame. (3) The tip end of the first metal piece is positioned adjacent to the second metal piece, and the tip end of the first metal piece and the tip end of the second metal piece are rotatably connected to each other by a connecting piece. The present invention also provides a folding chair that is configured to satisfy all of the following requirements: (1) A front leg stay is installed between the front leg frames at a position forward of the second horizontal axis, and when in use, the front leg stay is positioned on the underside of the seat frame. (2) A stopper is protrudingly provided on the underside of the seat frame at a position between the second horizontal axis and the second metal piece. (3) In the folded state, the front leg stays are brought into contact with the stoppers so as to restrict further rotation of the seat frame.

[0009] In the above, "the lower end of the front leg frame and the lower end of the rear leg frame touching the ground" includes cases where the lower ends of the frames touch the ground, and also includes a configuration in which the lower ends of the front leg frame and the lower ends of the rear leg frame are bent laterally to form horizontally bent parts, and the whole or part of the horizontally bent parts touch the ground. Effect of the Invention

[0010] In the present invention, the upper end of the axially extendable rear leg frame is connected to the front leg frame by a first horizontal shaft, the seat frame and the front leg frame are connected by a second horizontal shaft, and the seat frame and the rear leg frame are connected via a shape maintaining mechanism. Therefore, it is possible to absorb the change in the relative position of each frame when the seat frame is in the horizontal position when in use or when the seat frame is in the vertical position when folded, and the deformation caused by the extension of the rear leg frame, and it is possible to achieve a structure in which the lower end of the front leg frame and the lower end of the rear leg frame are in contact with the ground surface in both the use state and the folded state. Since the lower end of the front leg frame and the lower end of the rear leg frame can be in contact with the ground surface even in the folded state, the folding chair can stand on its own when folded. In addition, the shape retention mechanism is constructed by connecting a first metal fitting on the rear leg frame and a second metal fitting on the seat frame directly or via another member, so that there is no cross-sectional loss in each frame, and the strength of the folding chair is maintained while a simple structure can be used to achieve a state in which the lower ends of the front leg frames and the lower ends of the rear leg frames are in contact with the ground surface. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a first embodiment of the present invention, in which (a) is a plan view of the upper side and (b) is a bottom view of the lower side, (c) is a side view. [Diagram 2] In the first embodiment of the present invention, (a) is an enlarged view of part A in FIG. 1(c) in use, (b) is an enlarged view of part A in a folded state, and (c) is a plan view of the enlarged view of part A. [Diagram 3] FIG. 1 is a side view of a first embodiment of the present invention, in which (a) is in use, (b) is in the middle of folding, (c) is in the folded state, and (d) is in the folded state of the folding chairs nested together. [Figure 4]In another embodiment of the first embodiment of the present invention, (a) is an enlarged view of part A in FIG. 1(c) in a used state, (b) is an enlarged view of part A in the middle of folding, (c) is an enlarged view of part A in a folded state, (d) is a partial plan view of (a), and (e) is a partial plan view of (c). [Diagram 5] FIG. 1 shows a second embodiment of the present invention, in which (a) is a bottom view, (b) is a side view, and (c) is a front view. [Figure 6] In the second embodiment of the present invention, (a) is an enlarged view of part B in FIG. 5(b), (b) is a partial plan view of (a), (c) is a cross-sectional view of the area around the locking pin in (a), and (d) is a partial front view of (a). [Figure 7] 1A and 1B are side views of a second embodiment of the present invention, in which (a) shows the device in a use state and (b) shows the device in a folded state; [Figure 8] In this embodiment of the second embodiment of the present invention, (a) is an enlarged view of part C in FIG. 5(a) (in use state), (b) is an enlarged view of part B in FIG. 5(b) (in use state), and (c) is an enlarged view of part D in FIG. 7(b) (folded state). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1. First embodiment (first invention)

[0013] (1) Basic structure of folding chair 50

[0014] (1-1) The folding chair 50 is configured such that the front leg frames 20, 20 are arranged diagonally with respect to the seat frame 1 so as to sandwich the seat frame 1 from both sides (outside) in a plan view on the seat frame 1 arranged substantially horizontally, and are rotatably attached to the seat frame 1 by a second horizontal shaft 7. The rear leg frames 30, 30 are arranged so as to sandwich the front leg frames 20, 20 from the outside of the front leg frames 20, 20 in a plan view, and the rear leg frames 30, 30 are arranged diagonally with respect to the seat frame 1 and the front leg frame 20 in a side view, and the rear leg frames 30, 30 are rotatably attached to the front leg frames 30, 30 by a first horizontal shaft 27 (FIGS. 1(a)(c)).

[0015] (1-2) The seat frame 1 supports the periphery of the seat 6 on which the user sits, is made of pipes or the like, and is a generally rectangular ring-shaped member in plan view, with the front side 2 facing the user's feet, the rear side 2a facing the back, the sides perpendicular to the front side 2 and the rear side 2a being the sides 3, 3, and the direction from side 3 to side 3 being the width direction. Here, the seat frames 1, 1 are shaped so that the center is lowered and both side parts 3, 3 are bent upward.

[0016] (1-3) The front leg frames 20, 20 are a pair of left and right front leg frames made of pipe material or the like, with their lower ends 22 grounded on the ground surface 53 and their upper ends connected by a front leg upper connecting member 23 formed by bending the front leg upper connecting member 23 approximately horizontally at 21, 21. A back plate 24 is attached to the front leg upper horizontal connecting member 23. Usually, the front leg frames 20, 20 and the front leg upper horizontal connecting member 23 are formed by bending a single pipe material into a gate shape, but the manufacturing method is arbitrary. The front landing gear frames 20, 20 are connected by a front landing gear intermediate connecting member 25 which is generally horizontal and at a height slightly above the ground contact surface 53. The front leg frames 20, 20 are arranged diagonally with respect to the seat frame 1 so that their lower ends 22 face forward, and are arranged to sandwich the seat frame 1. Both ends of a second horizontal shaft 7, which is provided in the width direction at approximately the center of the seat frame 1 in the fore-and-aft direction, are attached to the front leg frames 20, 20 so as to be freely rotatable, thereby connecting the front leg frames 20, 20 to the seat frame 1.

[0017] (1-4) The rear leg frames 30, 30 are a pair of left and right rear leg frames made of pipe material or the like, and are configured by inserting a straight rear leg base 31 and a rear leg upper end portion 33, which is axially movable relative to the rear leg base 31, into the upper end side of the rear leg base 31. The lower end portion 32 of the rear leg base 31 becomes the lower end portion of the rear leg frame 30, and the lower end portion 32 of the rear leg base 31 contacts the ground surface 53. The lower end of the rear leg upper end portion 33 is restricted by a locking pin 46 provided on the rear leg base 31 so as not to drop below the locking pin 46 (normally, it is in use in this state). The rear leg frame 30 is disposed at an angle with its upper end (upper end connecting portion 35 of the rear leg upper end portion 33) in contact with the front leg frame 20 and its lower end (lower end portion 32 of the rear leg base portion 31) separated from the lower end portion 22 of the front leg frame 20. At this time, the middle portion of the rear leg frames 30, 30 is located near the rear side 2a of the seat frame 1 in the fore-and-aft direction of the seat frame 1 (this is the position in which the chair is normally used; see FIG. 1). The rear leg upper end 33 of the rear leg frame 30 is formed from a straight upper end base 34 that is inserted into the rear leg base 31, and an upper end connecting part 35 that is bent from the upper end base 34 towards the front leg frame 20. The tip of the upper end connecting part 33 is rotatably connected to the middle part of each front leg frame 20, 20 by a first horizontal shaft (rivet) 27.

[0018] (2) Characteristic embodiment of the first embodiment

[0019] (2-1) A rear leg stay 40 is attached between both rear leg frames 30, 30, on the surface of the rear leg frame 30 facing the front leg frame 20, below the underside 4a of the seat frame 1. The rear leg stay 40 is constructed by fixing a leg installation member 42 to leg fixing members 41, 41 which are fixed to the rear leg bases 31, 31 of both rear leg frames 30, 30. Each leg fixing member 41 is disposed approximately perpendicular to the axial direction of the rear leg base 31 (rear leg frame 30), and the leg installation member 42 is disposed linearly and approximately horizontally. Plate-shaped first metal fitting pieces 44, 44 are fixed to protrude toward the front leg frame 20 side (the underside 4a side of the seat frame 1) of the leg installation member 42. The first metal fitting piece 44 is disposed at a slight incline toward the front leg frame 20 side and the underside 4a side of the floor frame 1 with respect to the axial direction of the leg fixing member 42 (FIGS. 1(c), 2(a) and 2(b)).

[0020] (2-2) The seat stay 10 is attached to the underside 4a of the seat frame 1, between the front leg frame 20 and the rear leg frame 30. The seat stay 10 is constructed by installing and fixing a seat installation member 12 to a seat fixing member 11 fixed to both side parts 3, 3 of the seat frame 1. The seat fixing member 11 is disposed substantially vertically (substantially perpendicular to the underside 4a of the seat frame 1), and the seat installation member 12 is disposed linearly and substantially horizontally. A plate-shaped second metal fitting piece 14 is protrudingly fixed to the underside of the seat installation member 12. The second metal fitting piece 14 is disposed in a position along the first metal fitting piece 44 in a plan view, and is slightly inclined toward the rear leg frame 30 side (rear leg stay 40 side) with respect to the axial direction (substantially vertical direction) of the seat fixing member 11 (Fig. 1(c), Fig. 2(a)(b)). In addition, the tip end of the first metal piece 44 and the tip end of the second metal piece 14 are rotatably connected by a horizontal rivet (pin) (FIG. 2).

[0021] (2-3) Although the first metal fitting piece 44 and the second metal fitting piece 14 are provided in two symmetrical positions on the rear leg stay 40 (on the leg mounting member 42), it is possible to install at least one piece. (2-4) In the manner described above, the folding chair 50 of the present invention is constructed (FIGS. 1, 3(a), 2(a) and 2(c)).

[0022] (3) Use of folding chair 50

[0023] (3-1) When the folding chair 50 is in use, i.e., when the user sits on the seat 6, the seat frame 1 is positioned almost horizontally, and the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 are in contact with the ground surface (the ground, the floor of a building, etc.) 53. In this state, the lower end of the straight base 34 of the rear leg connecting part 33 of the rear leg frame 30 abuts against the locking pin 36, restricting the rear leg connecting part 33 from moving downward relative to the rear leg base 31. This allows the opening angle between the front leg frame 1 and the rear leg frame 30 to be maintained, allowing the user to sit stably (Figs. 1, 2(a)(c), 3(a)). Furthermore, by adjusting the angle between the first metal fitting piece 44 and the second metal fitting piece 14, the opening angle between the front leg frame 20 and the high leg frame 30, i.e., the height of the seat portion 6 (seat frame 1), can be slightly adjusted.

[0024] (3-2) When the folding chair 50 is not in use, if the front side 2 of the seat frame 1 is raised, the seat frame 1 rotates around the second horizontal axis 7 so that the rear side 2a is lowered. Accordingly, the rear leg frame 30 rotates around the first horizontal axis 27, and the straight base portion 34 of the rear leg connecting portion 33 is pulled out from the upper end of the rear leg base portion 31. In this case, too, the change in the distance between the rear leg frame 30 and the seat frame 1 (the distance between the leg installation member 42 of the rear leg stay 40 and the seat installation member 12 of the seat stay 10) can be absorbed by changing the angle of the first metal fitting piece 44 and the second metal fitting piece 14, so that the lower end portion 22 of the front leg frame 20 and the lower end portion 32 of the rear leg base portion 31 of the rear leg frame 30 can be maintained in contact with the ground surface 53 (FIG. 3(b)).

[0025] (3-3) If the front end 2 of the seat frame 1 is subsequently pulled up, the chair is folded (FIG. 3(c)). In this state, the rear leg support member 42 of the rear leg stay 40 comes into contact with the underside of the seat 6 (the underside 4a of the seat frame 1), restricting further lifting of the front end 2 of the seat frame 1 (FIG. 2(b)). Even in this folded state, the change in the distance between the rear leg frame 30 and the seat frame 1 (the distance between the leg support member 42 of the rear leg stay 40 and the seat support member 12 of the seat stay 10) is absorbed by changing the angle of the first metal fitting piece 44 and the second metal fitting piece 14, so that the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 can be kept in contact with the ground surface 53 (FIG. 3(c)). Thus, the folding chair 50 in the folded state can stand on its own.

[0026] (3-4) In addition, when multiple folding chairs 50 are folded, and the underside 4a of the seat frame 1B of the rear folding chair 50B is brought close to the upper surface 4 of the seat frame 1A of the front folding chair 50A, the front leg frame 20B of the rear folding chair 50B is positioned outside the side surface 3 of the seat frame 1A of the front folding chair 50A, and the rear leg frame 30B of the front leg frame 20B of the rear folding chair 50B is positioned outside the front leg frame 20A of the front folding chair 50A, allowing them to be nested (FIG. 2(d)). At this time, the lower end portion 22 of the front leg frame 20 and the lower end portion 32 of the rear leg base portion 31 of the rear leg frame 30 of each folding chair 50, 50 are in contact with the ground surface 53, so that the chairs stand independently without the need for support by the worker, making nesting work easy. Similarly, each folding chair 50 can be easily pulled out from the nested state.

[0027] (3-5) In addition, in the folded state, the seat stay 10, second metal piece 14, rear leg stay 40 and first metal piece 44 of each folding chair 50 are all positioned below the second horizontal axis 7 of the seat frame 1, so that when nesting, the front and rear folding chairs 50, 50 protect the first metal piece 44 and second metal piece 14 and do not interfere with the other folding chairs 50.

[0028] (4) Other embodiments of the folding chair 50

[0029] (4-1) A stopper 16 can also be attached to the folding chair 50 (FIG. 4). The stopper 16 is a small block-like member, and is fixed to the underside 4a of the seat stay 1 of the folding chair 50, near the rear leg support member 42 of the rear leg stay 40 (slightly closer to the front end 2) in plan view, and between the seat stay 10 and the rear leg frame 30 in side view. When the folding chair 50 is in use, the stopper 16 does not come into contact with the seat stay 10, second metal fitting piece 14, rear leg stay 40, first metal fitting piece 44, etc., so the user can use the folding chair 50 stably in the same manner as described above (FIGS. 4(a)(d)). Furthermore, when the folding chair 50 is not in use, if the front side 2 of the seat frame 1 is raised in the same manner as described above, the seat frame 1 will rotate about the second horizontal axis 7 and the rear leg frame 30 will rotate about the first horizontal axis 27 while the straight base portion 34 of the rear leg connecting portion 33 is pulled out from the upper end of the rear leg base 31. Even in this state, the stopper 16 does not come into contact with the seat stay 10, the second metal fitting piece 14, the rear leg stay 40, the first metal fitting piece 44, etc. (Fig. 4(b)), so that the lower end portion 22 of the front leg frame 20 and the lower end portion 32 of the rear leg base 31 of the rear leg frame 30 can maintain their contact with the ground surface 53 in the same manner as described above (see Fig. 3(b)). In the folded state where the front end 2 of the seat frame 1 is subsequently raised, the stopper 16 comes into contact with the rear leg support member 42 of the rear leg stay 40, restricting further elevation of the front end 2 of the seat frame 1 (FIGS. 4(c)(e)). Also, in this folded state, the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 can maintain a state of contacting the ground surface 53, as described above (see FIG. 3(c)). Therefore, the folding chair 50 in the folded state can stand on its own, and nesting and unnesting operations can be easily performed, as described above (see FIG. 3(d)). By using this stopper 16, the inclination of the seat frame 1 in the folded state and the opening angle between the front leg frame 20 and the rear leg frame 30 can be easily changed without changing the mounting positions and sizes of the seat stay 10, rear leg stay 40, first metal fitting piece 44, second metal fitting piece 14, etc.

[0030] (4-2) The seat frames 1, 1 are shaped so that the center is lowered and both side portions 3, 3 are bent upward, and by making the seat frame 1 bent, it becomes easier to set each member in a position where the second metal fitting piece 14, the first metal fitting piece 44, and the rear leg stay 40 do not interfere with each other in the folded state, particularly in a position where they do not interfere with the underside 4a of the seat frame 1. However, the seat frame 1 can also be shaped like any ordinary seat frame 1, such as a flat shape (not shown).

[0031] 2. Second embodiment (second invention)

[0032] (1) Basic structure of folding chair 70 The basic structure of the folding chair 70 is the same as that of the first embodiment of the invention, but there are the following differences. In the second aspect of the invention, the seat frame 1 has a flat structure. In the second invention, the front leg frame 20 is not linear below the second horizontal axis 7, but is linear below the front leg bent section 28 that is bent from the second horizontal axis 7 toward the front end 2 of the seat frame 1, and reaches the lower end 22 (Fig. 5(b)). The front leg bent section 28 makes it possible to increase the front-to-rear distance between the lower end 22 of the front leg frame and the lower end 32 of the rear leg frame 30 (rear leg base 31) even when the front leg frame 1 and the rear leg frame 30 have a small opening angle around the first horizontal axis 27, thereby improving stability when in use.

[0033] (2) Characteristic embodiment of the second embodiment

[0034] (2-1) A seat reinforcing member 8 is installed and fixed between the inner surfaces of the side surfaces 3, 3 of the seat frame 1. This seat reinforcing member 8 protrudes slightly from the lower surface 4a of the seat frame (FIGS. 5(a) and 5(b)).

[0035] (2-2) A front leg stay 60 is installed and fixed to the front leg bent portion 29 below the second horizontal shaft 7 of the front leg frames 1, 1. The front leg stay 60 has both ends bent and includes a front leg fixing member 61 fixed to the front leg frames 1, 1, and a straight front leg installation member 62. In addition, when in use, the front leg support member 62 of the front leg stay 60 abuts against the seat reinforcement member 8, preventing the front side 2 of the seat frame 1 from dropping relative to the seat frame 1, i.e., preventing the front leg frame 1 and the rear leg frame 30 from opening apart.

[0036] (2-3) A second metal fitting piece 14 is fixed to protrude downward from the lower surface 4a of the seat frame 1. The second metal fitting piece 14 is disposed in the vicinity of the rear leg frame 40, between the second horizontal shaft 7 (front leg frame 20) and the rear leg frame 40 in a side view (FIGS. 6(a) and 8(a)). A first metal fitting piece 44 is fixed to protrude from the rear leg base 31 of the rear leg frame 30, on the front leg frame 20 side, at a substantially right angle to the axis of the rear leg frame 30. The first metal fitting piece 44 is located on the underside 4a of the seat frame 1, near the second metal fitting piece 14. One end 64a of a connecting piece 64 is rotatably connected to the tip of the first metal fitting piece 44. The other end 64b of the connecting piece 64 is rotatably connected to the tip of the second metal fitting piece 14 (FIG. 6). The first metal fitting piece 44 is fixed to both rear leg frames 30, 30 (rear leg bases 31, 31), and correspondingly, the second metal fitting pieces 14 are fixed to both sides of the seat frame (FIGS. 5(a) and 5(c)).

[0037] (2-4) In addition, a stopper 17 is fixed to the underside 4a of the seat frame 1, at a position between the second rotating shaft 7 (front leg frame 20) and the second metal piece 14 in a side view. The stopper 17 does not contact any components when in use, and abuts against the front leg stay 60 in the folded state, thereby acting to regulate the structure in the folded state.

[0038] (2-5) In the manner described above, the folding chair 70 of the second aspect of the invention is constructed (FIGS. 5 and 6).

[0039] (3) Use of folding chairs 70

[0040] (3-1) As in the case of Invention 1 above, when the folding chair 70 is in use, i.e., when the user is seated on the seat 6, the seat frame 1 is positioned approximately horizontally, and the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 are in contact with the ground surface 53 (the ground, a building floor, etc.). As in the case of Invention 1, the lower end of the straight base 34 of the rear leg connecting part 33 of the rear leg frame 30 abuts against the locking pin 36, restricting the rear leg connecting part 33 from moving downward relative to the rear leg base 31. This maintains the opening angle between the front leg frame 1 and the rear leg frame 30, allowing the user to sit stably (Figs. 5, 6(a)(c), 7(a), 8(b)). In this state, the lower end of the straight base portion 34 of the rear leg connecting portion 33 of the rear leg frame 30 abuts against the locking pin 36, and the seat reinforcement member 8 of the seat frame 1 abuts against and presses against the front leg mounting member 62 of the front leg stay 60, thereby suppressing pressure on the first metal fitting piece 44, the second metal fitting piece 14 and the connecting metal fitting piece 64 (Figure 6). In this state, the first metal fitting piece 44 and the second metal fitting piece 14 are in a generally furthest positional relationship, and are connected to the connecting metal fitting piece 64 in this state.

[0041] (3-2) When the folding chair 70 is not in use, if the front side 2 of the seat frame 1 is raised, the seat frame 1 rotates around the second horizontal axis 7 so that the rear side 2a is lowered. Accordingly, the rear leg frame 30 rotates around the first horizontal axis 27, while the straight base portion 34 of the rear leg connecting portion 33 is pulled out from the upper end of the rear leg base 31. In this case, too, the change in the distance between the rear leg frame 30 and the seat frame 1 (the distance between the leg installation member 42 of the rear leg stay 40 and the seat installation member 12 of the seat stay 10) can be absorbed by changing the relative position of the first metal fitting piece 44 and the second metal fitting piece 14 and by changing the angle of the connecting piece 64, so that the lower end portion 22 of the front leg frame 20 and the lower end portion 32 of the rear leg base 31 of the rear leg frame 30 can be maintained in contact with the ground surface 53.

[0042] (3-3) If the front end 2 of the seat frame 1 is subsequently pulled up, the chair is folded (FIG. 7(b)). In this state, the front leg fixing member 61 of the front leg stay 64 comes into contact with the stopper 17 of the seat frame 1, restricting further lifting of the front end 2 of the seat frame 1 (FIG. 7(b), FIG. 8(c)). Even in this folded state, the change in the relative position of the first metal fitting piece 44 and the second metal fitting piece 14 and the connecting piece 64 can be absorbed by changing the angle, so that the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 can be kept in contact with the ground surface 53 (FIG. 7(b)). Thus, the folding chair 70 in the folded state can stand on its own. In addition, in the folded state, the first metal fitting piece 44, the second metal fitting piece 14 and the connecting piece 64 are located between the front leg frame 20 and the rear leg frame 30 (rear leg base 31) in a side view. In addition, in the folded state, the first metal fitting piece 44, the second metal fitting piece 14 and the connecting piece 64 are located on the rear leg frame 30 (rear leg base 31) side of the front leg mounting member 62 of the front leg stay 60 (FIG. 8(c)). Therefore, when the folding chairs 70 in the folded state are nested, the front leg mounting member 62 of the rear folding chair 70 comes into contact with the upper surface 4 of the seat frame 1 of the front folding chair 70, thereby protecting the first metal piece 44, the second metal piece 14 and the connecting piece 64 of the rear folding chair 70 (Figure 8(c)).

[0043] (3-4) When returning the folding chair 70 from the folded state to the usable state, the folding chair 70 can be easily returned to the usable state by lowering the front side 2 of the seat frame 1.

[0044] (3-5) Furthermore, similarly to the case of Invention 1, the nesting and unnesting of folding chairs 70 in the folded state maintains the lower end 22 of the front leg frame 20 and the lower end 32 of the rear leg base 31 of the rear leg frame 30 in contact with the ground surface 53, thereby making it possible to efficiently nest and unnest multiple folding chairs 70 in the folded state (see Figure 3(b)).

[0045] (4) Other embodiments of the folding chair 70

[0046] (4-1) In the folding chair 70, when the relative position between the front leg stays 60 and the seat frame 1 is changed in the folded state, the height and position of the stopper 17 can also be changed (not shown).

[0047] (4-2) Although the front leg frame 20 of the folding chair 70 is provided with the bent portion 28, the front leg frame 20 may have a commonly used configuration such as a straight shape without the bent portion 28 (not shown). [Explanation of symbols]

[0048] 1 Seat Frame 2. Front end of seat frame 2a Rear end of seat frame 3, 3a Side of seat frame 4 Top of seat frame 4a Underside of seat frame 6 Seat frame seat 7 Second horizontal axis (seat frame, front leg frame) 8 Seat reinforcement member for seat frame 10 Seat stay (shape maintenance mechanism) 11 Seat fixing member for seat stay 12 Seat support member 14 Second metal piece (Second metal piece. Shape maintenance mechanism) 16 Stopper 17 Stopper 20 Front landing gear frame 21 Upper end of nose landing gear frame 22 Upper end of nose landing gear frame 23. Upper connecting member for nose landing gear 24 Backboard 25. Front landing gear intermediate connecting member 27 First horizontal axis (front leg frame, seat frame) 30 Rear leg frame 31 Rear leg base of rear leg frame 32 Lower end of hind leg base 33 Rear leg connection part of rear leg frame 34 Straight base of rear leg joint 35 Upper end of rear leg connection (upper end of rear leg frame) 36 Rear leg frame locking pin 40 Rear leg stay (shape maintenance mechanism) 41 Leg fixing member for rear leg stay 42 Rear leg stay leg installation member 44 First metal piece (shape maintenance mechanism) 50 Folding Chair 53 Ground plane 60 Front leg stay 61 Front leg fixing member for front leg stay 62 Front landing gear stay, front landing gear installation member 64 Connecting piece (shape maintenance mechanism) 70 Folding Chair

Claims

1. It is a folding chair that can be transformed into a sitting position and a folded position. A pair of front leg frames, a pair of rear leg frames, and a substantially horizontal seat frame are provided, The front landing gear frame has a lower end connected to the ground and an upper end connected to an upper connecting member. The rear landing gear frame has a lower end connected to the ground and an upper end connected to an upper portion of the front landing gear frame, A folding chair characterized in that the middle part of the seat frame is sandwiched in the width direction by the middle part of the front leg frame and is rotatably connected to the front leg frame at said part by a second horizontal axis, and is configured to satisfy all of the following requirements. (1) Each of the rear leg frames is formed from a rear leg base portion whose lower end is grounded, and a rear leg upper end portion which is axially movable and extendable relative to the rear leg base portion. (2) Each of the front leg frames was rotatably connected to the upper end of the rear leg upper end of each of the rear leg frames at a position above the seat frame by a first horizontal axis. (3) The intermediate portions of the front leg frames and the seat frame are connected to each other below the first horizontal axis so as to be freely rotatable about a second horizontal axis formed on the seat frame. (4) A shape maintenance mechanism is provided which absorbs deformation due to extension of the rear leg frame and changes in the relative positions of each frame due to the seat frame rotating around the second horizontal axis in the folded state, and the seat frame and the rear leg frame are connected via the shape maintenance mechanism. (5) The shape retention mechanism is configured by rotatably connecting, directly or via other members, a first metal fitting provided on the front leg side of the rear leg frame and on the underside of the seat frame to a second metal fitting protruding from the underside of the seat frame. (6) The shape retention mechanism is structured so that, in the use state and the folded state, the lower end of the front leg frame and the lower end of the rear leg base of the rear leg frame both maintain contact with the ground, so that the seat frame is in a substantially horizontal position in the use state and is in an upright position in the folded state. (7) The lower ends of the front landing gear frames and the rear landing gear frames are not provided with means for rotating with respect to the ground surface, and are designed so that they do not easily move relative to the ground surface when in use.

2. 2. A folding chair according to claim 1, characterized in that it is configured to satisfy all of the following requirements: (1) A rear leg stay is installed between the rear leg frames, on the front leg frame side of the rear leg frames and on the underside of the seat frame, and a first metal fitting is fixed to the rear leg stay. (2) The rear leg stay is composed of a leg fixing member fixed to the rear leg frame and a leg installation member connecting both the leg fixing members, and the first metal fitting is fixed to the leg installation member. (3) A seat stay is installed between the second horizontal axis and the rear leg frame on the underside of both sides of the seat frame, and a second metal fitting is fixed to the seat stay. (4) The seat stay is composed of a seat fixing member fixed to both sides of the seat frame and a seat installation member connecting the two seat fixing members, and the second metal fitting is fixed to the seat installation member.

3. 3. The folding chair according to claim 2, characterized in that it is configured to satisfy all of the following requirements: (1) The first and second metal fittings are small plate-shaped first metal fitting pieces and second metal fitting pieces, and the first metal fitting piece is fixed to the leg mounting member with its tip inclined toward the second metal fitting piece, and the second metal fitting piece is fixed to the seat fixing member with its tip inclined toward the first metal fitting piece. (2) The tip end of the first metal piece and the tip end of the second metal piece are rotatably connected to each other.

4. 4. The folding chair according to claim 3, characterized in that it is configured to satisfy all of the following requirements: (1) A stopper is provided on the underside of the seat frame, between the seat stay and the rear leg frame when viewed from the side, protruding downward. (2) The stopper is not in contact with the rear leg stay or the seat stay in the use state, and is in contact with the leg support member of the rear leg stay in the folded state.

5. 2. A folding chair according to claim 1, characterized in that it is configured to satisfy all of the following requirements: (1) The first and second metal fittings are small plate-shaped first and second metal fitting pieces, and the first metal fitting piece is fixed to the rear leg frame at a position on the front leg frame side facing the front leg frame, and the first metal fitting piece is positioned on the underside of the seat frame. (2) A second metal fitting piece was fixed downward to the underside of the seat frame. (3) The tip end of the first metal piece is positioned adjacent to the second metal piece, and the tip end of the first metal piece and the tip end of the second metal piece are rotatably connected to each other by a connecting piece.

6. A folding chair according to claim 5, characterized in that it is configured to satisfy all of the following requirements: (1) A front leg stay is installed between the front leg frames at a position forward of the second horizontal axis, and when in use, the front leg stay is positioned on the underside of the seat frame. (2) A stopper is protrudingly provided on the underside of the seat frame at a position between the second horizontal axis and the second metal piece. (3) In the folded state, the front leg stays are brought into contact with the stoppers so as to restrict further rotation of the seat frame.

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